CA1256257A

CA1256257A - Methods and apparatus for injection molding and injection blow molding multi-layer articles and the articles made thereby

Info

Publication number: CA1256257A
Application number: CA000451813A
Authority: CA
Inventors: William A. Tennant; Henry Pfutzenreuter, Iii; Frederick G. Kudert; Thomas T. Tung; Maurice G. Latreille; Robert J. Mchenry; George F. Nahill; John Vella, Jr.
Original assignee: American National Can Co
Current assignee: Rexam Beverage Can Co
Priority date: 1983-04-13
Filing date: 1984-04-12
Publication date: 1989-06-27
Also published as: CA1303806C; US4712990A; ZA842782B

Abstract

ABSTRACT OF THE DISCLOSURE
In a method of forming multi-layer plastics articles employing a multi-cavity injection molding machine, a combined material stream is injected from each of a plurality of coin-jection nozzle means of the machine into an associated injec-tion cavity to form each article. The method further involves providing streams of polymeric materials to form the corre-sponding layers of the articles, and moving each material stream separately to each of the nozzle means, forming the combined stream in the plural nozzle means from the separate material streams, and injecting the combined streams to form the multi-layer plastics articles.

Description

FIELD OF T~E INVENTION

The present invention is concerned with improved multi-layer injection molded ancl injection blow molded articles, apparatus to manufacture such articles and methods to produce them.

BACRG~OUND OF T~E _NVENTION

Containers for packaging food require a combination of physical properties which i5 not economically available with rigid and semi-rigid containers made rom any single polymeric material. Among the properties required are low oxygen and moisture permeability, compatibility with the temperatures and pressures encountered in conventional food proce~ing and steriliza~ion, and the impact resis~ance and rigidity required to withstand shipping, warehousing, and abuse. Multi-layer constructions comprised of more than one plastic material can offer such a combination of properties.

Multi-layer containers have been made commercially by thermoforming and extrusion blow molding processes. These processes, however, suffer from major disadvantages~ The chief disadvantage is that only a portion of the multi-layer material formed goes into the actual containerO The remainder of the matesial can sometimes be recovered and used either in other applications or in one of the layers of future containers made by the same process. This "recycle"
use, however, recovers only a part of the vaLue of the , ' ~ 256~7 original material because the scrap is a mixture o~ the mate-rials~ Other disadvantages of these processes include limited op-tions in terminal end geometry or ~finish~, in shape, and in material distribution.
Injection molding and injection blow molding are of-ten preferred for making single layer containers because they are scrapless and overcome many of the other limitations of thermoforming and extrusion blow molding. These processes have not been commercially adapted to multi-layer construc-tions because of difficulties in achieving the required con-trol of the location and uniformity of the various layers, particularly on a multi-cavity basis. In fact, even on a single cavity basis, multi-layer injection molding has been limited to relatively thick parts in which a thin surface layer of plastic covers a relatively thick core layer of either foamed plastic or of some other aesthetically unattrac-tive material such as scrap plastic.
To be successfully commercially adapted to food con-tainers, multi-layer injection molding would require two major improvements over the processes which are now commercially practiced. Economical multi-layer food containers require very thin core layers comprised of relatively expensive bar-rier resin such as a copolymer comprised of vinyl alcohol and ethylene monomer units. The location and continuity of these thin core layers are important and must be precisely con-trolled. U.S. Patent No. 4,525,134, issued June 25, 1985 and U.S. Patent No. 4,526,821, issued July 2, 1985, each assigned to the assignee o:E this application disclose multi-layer, in;ection molded and injec-tion blow molded articles, parisons and containers having a thin continuous core layer substan-tially encapsulated within inner and outer structural layers, and methods and apparatus to make them. The disclosures in 5~;2~7 the aforementioned U.S. patents apply to both single and multi-cavity injection moldlng machines.

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5 6 zr37 ~ he second improvement over current commercial multi-layer injection molding processes is that the proress must be capable of forming con~ainers on a multi-cavity basis. Although the relatively large parts made by current commercial multi-layer processes can be economically practiced on a single cavity basis, food containers, which are relatively small, require a multi-cavity process to be economical. The e~ten~ion ~rom single cavity processes to an acceptable multi-cavity process presents many serious technical difficulties.

One way to extend from a ~ingle cavity to a multi-cavity process would be to replicate for each cavity the polymeric material melting and displacement and other flow distributing means used in a single cavity process~
Such replication wQuld realize ~ome advantages over a unit cavity process. ~or exampl~, a common clamp means could be used~, lIowever, it would not provide the maximum advantage because individual polymeric material melti~g and ~isplacement means would still be necessary. Such a ~ultiplicity of melting and pressurization means would not only be costly but would create severe geometrical an~ de~ign proble~ of positionir~g a large number of separate flow st~eams in a balanced configurationJ thereby increasing the required spacin~ between cavities, and llmiting the number of ca~ities which would it within the area of the clamped platens .

An alternate means of molding multi-layer articles on a multi-cavity basis would be to have a single multi~layer nozzle wit]h its associated melting~ displacement and distributing means communicate with a single channel or runner ~eeding multiple materials to muLtiple cavities. Such a runner system might be either of the cold runner type in which the plastio in the runner is cooled and removeâ with the inject:Lon molded article in each cycle, or of tha ho~
runner type in which the plastic remaining in the runner after each shot is kept hot and is injected into the cavities ~ 5 ~ 7 during subsequent shots. The chief limitation of this single runner approach is that the single runner channel itself would contain multiple materials which would make it very difficult to control the flow of the individual materials into each cavity, particularly for a process having elements of bo-th sequential and simultaneous flow such as that described in U.S. Patent NoO
4,526,821. Controlling the flow of multiple materials in a single runner would be even more difficult in a case in which the runner is long, as in a multi-cavity system.

In the preferred embodiments of the apparatus and methods of this invention, a single displacement source is used for each material which is to form a layer of the article, but the materials are kept separate while each material is split into several streams each feeding a separate nozzle for each cavity.
The individual materials are thereby combined into a multi-layer stream only at the individual nozzles, in their central channels, which feed directly into each cavity. Although this approach avoids many of the disadvantages of the previously described methods, it presents many problems which must be satisfactorily overcome for successful in;ection of articles in which thin core layers are properly distributed and located.

Several of these problems result from the length of the runner and the distribution system for a multi-coinjection nozzle machine. For economical reasons, it is desirable to have as many cavities as possible within the machine in order to provide as many articles as possible upon each injection cycle. It is possible to minimize the average runner length for a given number of cavities by having the channels run directly to the remotest nozzle, redirecting a part of the stream as it passes near each other nozzle. It has been found that such a channel geometry, while suitable for most single layer in~ection molding, has a ma;or disadvantage for precise multi-layer in;ection in that a , :
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given impetus introduced at the displacement or pressurization source will have its effect more ïmmediately in the more proximate nozzles than in the more remote oneqO
The time delay between the initiation of an impetus and its effect at a distance results from the compressibility of the plastic. ~ecause of this c:ompressibility, material must flow in the channel before a desired pressure change can be achieved at a remote location. It has been found that in order to achieve the same flow initlation and termination times and the same relative flow rates of various layers in each nozzle as well as to obtain articles from all cavities having substantially the same characteristics~
the material entering each nozzle must have undergone essenti lly the same flow experience in its path to the nozzle.
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It has further been found that in a system in which a given flow stream is spli~ into ~e~eral individual s~reams to ~aed each nozzle, the channel and devica geometries which ac~omplish each of these flow splittings must be symmetrically designed so a~ to provide the same flow experience to the material in each of the re~ultin~ split streams. Such s~mmetry is dif~icult to achieve with ~iscoelastic ~aterials such a-~ polymer melts because the ~aterials have a ~memory~ of their previous history. When a flow channel contains a sharp turn, or example, material which has passed near the inner radius of curvatur2 of that turn will have a diferent flow experience from the mate~ial which has passe~ near the outer radius of curvature.

Even with a runner system which, by its de~ign, minimizes the differences in flow hi~tory in the path to each nozzle, there will rem~in some differences as a resul~ of remaining memory effects, temperature non-uniformities in the melt stream before it is split, temperature non-uniformities in the runner system, and machining tolerances. For this reason, it would be desirable to have indepe~dent control - 12 - ~

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of the time of initiation a;nd termination of each flow, a critical requirement for prlecise control of thin core multi-layer injection molding. Such independent control should be effected as near as possible to the point at which the individual flow streams are combined into a multi-layer flow stream. ~:Lthough these control means should be located in each individual noz~le, they should be controlled in such a manner that they are 2ctuated simultaneously in desired nozzles of a multi-coinjection nozzle machine.

It is not sufficient that the 10w of each material be substantially identical in each nozzle. It is also necessary that the flow of the individual materials be uniformly distributed within each injection cavity and, hence, within the nozzle chanael ~eedin~ the cavity. For axi~ymmetrical articles, such as most ~ood containers, this is most readily achieved by shaping the various flow straams into concentric annular flows or by shaping one stream into a cylindrical flow and shaping the other flows into a~nula~
10ws concentric with that cylinder beore comblning the flow streams.

~ n order to achieve the required uniformity in these concentric annular flows, it is necessary to redistribute a given flow stream rom its shape as it le~ves the runner ~ystem into a balanced annular flow. Achieving such a balanced annular flow is difficult in itself but is much more difficult to achieve with an intermittent flow process than it i5r say, in conventional blown film dies where the flow is constant. Among the complexities of such an intermittent flow process are the difficulty of achieving flow balance when the rate of flow is deliberately varied during each cycle, and the additional problem of different time response behavior at various locations around the annulus.

An additional requirement for an acceptable multi-cavity, multi-layer runner system is that it accurately align and maintain an effective pressure contact seal between each nozzle with its respective cavity. This alignment is particularly critical for the injection o~ the internal layer of the multi-layer articles in that any misalignment will adversely affect the uniformity and location of the internal layer. The di~iculty in arhieving such alignment is that the metal for such a hot runner system is at a higher temperature than is the metal plate in which the cavities are mounted. Because of the thermal expansion o~ materials of construction normally used for such mold parts, the nozzle to nozzle distance will tend to grow with temperature more than will the cavity to cavity distance. In single layer, multi-cavity iniection molding, there are two conventional ways of compensating for this di~ference in thermal expansion. The first i4 to prevant the relative expansion or contraction by physical restraint; that is, by physically intarlocking the runner with the cavity plate. For a large runner system, such a physical constraint system will ~enerate large often problematical oppoging forces in the two parts. The second way is to siz8 the runner system so that it will align wi~h the cavity plate when it is at an elevated temperature within a narrow range, even though it will be misalig~ed beyond the range, e.g., at room temperature. ~n accordance with this invention, the runner syste~ is not attached to the cavity plate, but rather is left free to grow radially. The nozzles and cavity faces are flat to provide a liding interface. Given this feature, and that the cavity cprue orifices are provided with a l~rger diameter than that of the nozzle sprue orifices, the runner has a much greater opportunit:y to grow radially without the cavity and nozzle sprue orii.ices becoming misalignedO This provides a much broader temperature range within which to operate, and a wider range of possible polymer melt materials which can be used. ~owever, in order for the noz~les mounted in the runner to tran~fer plastic at high pressure to the cavities without leakage, it is necessary to impose an opposing force ~5~

ts counteract the separation force generated by this high pressure. This is conventionally achieved by transmitting all or part of the force of the injection clamp through the runner system to the fixed platen. An alternative methoa is, to use the axlal the-mal expansion of the runner system to generate a compressive force on the runner between the fixed platen and the cavity plate. One difficulty with any o the above methods o compensating for this differential expansion i~ that they re~uire close physical contact between the hot runner and the colder metal of the cavity plate and o~ the fixed platen. This close contact causes thermal variations in the runner. Whil~ such thermal gradients would be acceptable in a single layer runner system, the resulting differences in flow experience to each no~zle could for e~ample result in a significant variation in the uniformity and location of a thin inner layer in multi-layer injection molding. This invention overcomes these problems by mounting the runner system with minimum contact between it and surrounding structure.

Other problems encountered in multi-cavity injection molding of articles relates to the formation of high~barrier multi-layer plastic containers. Such containers require that th~ leading edge of the internal barrier layer material be extanded subgtantially uni~ormly into and about the marginal end portion of the,side wall of the parison or cOntain~!.
This condition is di~ficult to obtain, because of the compressibility of polymeric melt materials and the long runners of multi-cavity machine which result in a delay in ~low response which is accentuated the more remote the materials are from the sources of material displacement. In addition, there are the previously mentioned di~ficulties of achieving balanced annular flow and uniform time response due for example to variations in polymer and machine temperatures and in machining tolerances, and due to the intermittency of the flow process. These Iactors render it difficult to introduce ,a polymesic meit material uniformly and ~6;~

simultaneously over all points of it- orifice in one co-injection nozzle, and likewi5e with respect to introducing the corresponding material through coxresponding ori~ices in the plurality of co-iniection nozzles. It has been found that such an introduction is important to extending the leading edge uniformly into the marginal end portion of a container side wall because the portion of the annulus of material first introduced into the central channel will ~irst reach the marginal end portion of the parison or container side wall in the cavity, while the last introduced portion will trail and may not reach the marginal end portion. This condition, referred to as "time bias, n has been found to be one cause of bias in the leading edge of the internal layer, which is unacceptable for, for example, quality, high oxygen barrier containers for highly oxygen sensitive food products~

Another problem is that even i~ the internal layer material is introduced without time bias into the central channel~ there may still be bias in the leading edge of the inte~nal layer material in the side walL of the injected article, if all portions of the annulus of the leading edga of the internal layer material are not introduced into or onto a flow stream in the central channel ha~ing a-substantially uni~orm velocity about its circum~erence. This is difficult to achieve for one rea~on because the flow stream having a substantially uniform velocity about its circumference is not~necessarily radially uniform. I~ thi~
type o~ introduction occurs, there will be what is referred to as "velocity bias" in that the portions of the annulus in the central channel introduced onto a flow stream which has a high velocity will reach the marginal end portion o~ ~he side wall of the article in the cavity be~ore those portions o~
the annu;Lus introduced onto a ~low stream having a lower velocity Thus, in such case, other things being e~ual, even though there was no time bias in the introduction of the annulu c~f the internal layer material, a velocity bias in ~ ;~ 5 ~ 7 the central channel and cavity nevertheless resulted in a biased leading edge in the marginal end portion of the side wall of the injected article.
These and other problems associated with multi-layer unit and multi-coinjection nozzle injection molding and injec-tion blow molding machines, processes and articles are over-come by the apparatus, methods and articles of this invention.
According to the present invention there is provided a multi-coinjection nozzle injection molding apparatus for an injection molding machine for injection molding a multi-layer, multi-material plastic article, which compri.ses, a plurality of injection cavities mounted on a member, a plurality of jux-taposed coinjection nozzles each having a central channel, and polymer flow stream passageways in communication with the cen-tral channel, said central channel having an open 7 end, a gate at the open end, and a polymer material combining area in com-munication with the passageways and the gate, means for abut-ting the juxtaposed nozzles and injection cavities, a source of polymeric material located upstream of the nozzles for each material which is to form a layer of the article, means located upstream of the nozzles for displacing each polymer material which is to form a layer of the article from its source to a coin;ection nozzle passageway, and for pressuriz-ing each said material in its passageway, a separate flow channel for each polymer material which is to form a layer of the article, each channel being in communication with one of the displacement and pressurizing means, flow channel splitter means in communication with each said flow channel downstream of its associated displacement and pressurizing means, for splitting each said flow channel into a plurality of separate branched flow channels, there being a separate branched flow channel for each material which is to form a layer of the .~
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article, means in communication with a branched flow channel for each material which is to form a layer of the article and in communication with a coinjection nozzle, for separately feeding each separate polymer material to its associated coin-jection nozzle, a plurality of valve means cooperatively asso-ciated with the coinjection nozzles, said plurali-ty including separate valve means for each coinjection nozzle and operative in the combining area of the nozzle's central channel with respect to each polymeric material fed to the nozzle and which is to form a layer of the article, drive means for driving each of said separate valve means substantially simultaneously and substantially identically within the central channel of each of said coinjection nozzles to provide in each coinjec-tion nozzle substantially simultaneous and identical control over the initiation, regulation, and termination of the flows of the polymer materials through each of the coinjection noz-zles, and control means connected to the simultaneous drive means for moving the valve means in a desired mode which pro-vides said substantially identical simultaneous movements of said separate valve means in said respective coinjection noz-zles.

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SUMMARY OF T~E INVENTION

The present invention is concerned with injection molded and injection blow molded article~, including containers, whose walls are multiple plies of different polymers. In a preferred embodiment, the article is a container for oxygen-sensitive products including food products, the walls of the container are thin and contain an internal, extremely thin, substantially continuous oxygen-barrier layer, preferably of et~ylene vinyl alcohol, which is sub~tantially completely encapsulated within outer layers. The invention includes apparatus and methods for high-speed manufacture of such articles, parisons and containers, and the articles, parisons and containers themselv~s. The apparatus includes co-injection nozzle structure and valve means associated with the nozzle for precisely controlling the flow of ~t least three polymer st~eams through the nozzle which facilitates cont~nuous, high-speed manufacture in a multi-nozzle apparatus of ~ulti-layer, thin wall arti~les, parisons and containers, particularly those having therein a~ extremely thin, substantially conti~uous and substantially completely encapsulated int~rnal oxygen-barrier layer. The invention further comprises improved methods of producing such articles, pari ons and containers.

The apparatus comprises a nozzle havins a central channel ope~ at one end and having a flow pas~ageway in the nozzle ~or each polymer stream to be coinjected to form the multi-layer plastic articles from the polymer streams. Each o~ at least two o~ the nozzle passageways terminates at an exit orifi~e, preferably fixed and preferably annular, communicat:ing with the nozzle central channel at locations close to its open end. At least two of the nozzle passageways each comprises a feed channel portion, a primary melt pool portion, a secondary melt pool portion, and a final melt pool portion a part of which forms a tapered, symmetrical reservoir of polymer. The nozzle orifices - ~r-preferably are axially close to each other and close to the gate of the nozzle. Valve means, which may include sleeve means or pin and sleeve meansj are carried in the nozzle central channel and are move,able to selected positions to block and unblock one or mor~e of the orifices to prevent or permit flow of the polymer streams from the nozzle flow passageways into the nozzle central channel.

The valve means has at least one internal axial polymer flow passageway which ~ommunicates with the noz21e central channel and is adapted to communicate with one of the flow passageways in the nozzle. ~ovement of the valve means to selected positions brings the internal axial passageway into and out of communication with the nozzle passageway to permit or prevent flow of a polymer stream through that nozzle passageway and into the internal axial passageway of the valve means and then into the no2zle central channel.

When the valve me~ns comprlses sleeve means, or pin and sleeve mean~, it is preferred that communication from the i~ternal axial pas~ageway of the sleeve means to the passageway in the nozzle is through an aperture in ~he wall of the sleeqe means. It is al~o preferred that the leeve means fits closely within the nozzIe central channel so there is no substantial cavity for ~olymer accumulation between the outside of the sleeve means and the central channel.
Further, when the valve means is a sleeve means, it is preerred that the sleeve means have axial movement in the central channel of the nozzle (although it may also have rotational movement therein), so that when the sleeve is moved axially it blocks and unblocks one or more of the orifices. When lt ls rotatable and rotated, the aperture in the wall of the sleeve means is brought into and out of alignment with a nozzle passageway. Alternatively, the noz~le structure including that passageway may be rotated instead of rotatins the sleeve means.
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When the valve means comprises pi~ and sleeve me~ns, d ~7 the pin means preferaSly is moveable in the axial passageway of the sleave means to block and unblock an aperture in the wall of tbe sleeve means so as to interrupt and restore communication between the internal axial passageway in the sleeve and a nozzle passageway for polymer flow. The valve means of this invention can include a fixed pin over which the sleeve reciprocates axially and whose forward end cooperates with the sleeve aperture. One sleeve embodiment of this invention has axially-stepped outer wall surface portion~ of dif~erent diameter for use in a noz21e central channel having cooperative axially-stepped cylindrical portions of different diameters.

The valve means are adapted to assist in knitting the polymer melt material for forming the internal layer with itsel~ in the cen~ral channel, and/or to assi~t in encapsulating the internal layer with other polymeric mat2rial, and/or to substantially clear the central channel of polymer melt material when the valve ~eans is moved ax~ally forward through the central channel. In assisting in encapsulating the internal layer, the tip of the pin i5 partially withdrawn in the sle~ve and accumulates the encapsulating material in front of it ~ithln the sleeve, and as the valve means is moved forward, the pin can be msved relatively faster forward to eject the accumulated material ~rom the sleeve into the central channel~

The apparatu~ o the present invention further comprises, with the co-injection nozzle means, or the nozzle means and valve means of the present invention, the combination of polymer flow directing means in at least one of the nozzle passageways for balancing the ~low o~ at least one polymer stream around the passageway in the nozzle and the exit ori~ice through which it flows. The polymer flow directing means comprises cut-out sections in the nozzles which cooperate with eccentric and concentric chokes to direct the polymer stream exiting from a feed channel on one side of the nozzle into an annular stream whose flow is ~1 i62~

substantially evenly balanced around the circ~mference of the nozzle and associated exit o~ifice. In a preferred embodiment, the combination just described further includes means for pressurizing that polymer stream to produce a pressurized reservoir of polymer in the nozzle passageway between the $10w directing means and the orifice, whereby, when the valve mean~ is moved to unblock the orifice, the start of flow of the polymer through the orifice is prompt and substantially uniform around the circum~erence of the orifice. Prompt and uniform start of ~low of the polymer stream around the circumference of the orifice is important, particularly when the polymer stream whose flow is being thu~
controlled is the one which is to ~orm an internal, thin, substantially continuous layer of the injection molded and injection blow molded article. Such prompt, uniform start of 10w of the polymer to fQrm an internal layer greatly facilitates the pEoduction of mult~layer Injected articles in which an internal layer of the article extends substantially uni~ormly throughout th~ wall of the article particularly about the marginal end or edge portion of the article at the conclusion o~ polymer ~ovement i~ the injection cavity. ThiA is particularly important in the production of articles whi~h are to be containers for oxygen-sensitive food products where the internal, thin, oxygenobarrier layer must be substantially continuou3 throughout the ~all of the container.

The apparatus o this invention al~o includes a polymer flow stream redirecting and feeding device, preferably in the form of the feedblock of this invention, for receiving from a runner block a plurality of polymer flow ~treams separately directed at the device preferably at its peripheryr and, while maintaining them separate, redirecting them to flow axially out of the ~orward end of the device into the multi-polymer co-injection nozzle of this invention. In a preferred embodiment, flow Atreams enter radially into inlets in the periphery, travel about a portion of the circum~erence of the device, then inward through a channel toward the axis of the device and then axially forward and communicate wit:h exit holes in the forward end portion of the device. The! forward end portion has a stepped channel for receiving the shells of the nozzle assembly of this invention.

This invention further includes drive means which include common moving means for substantially simultaneously and identically driving each o the plurality of separate valva means through each co-injection nozzle and feedblock mounted in the multi-noz21e, multi-polymer injection molding machine, and provide in eacb nozzle, simultaneou~ identical control over the initiation, regulation and termination of flow of polymer materials through the noz~les. The drive means includes shuttles for the valve means and the common movin~ means includes cam bars for moving the respective shuttles, and hydraulic cylinders for moving the cam bars.
~9n~rol means are provided for moving the common moving m~ans ln a desired mode which provides the substantially simultaneous and identical movements and flow con~rolsO

The apparatus of this invention further includes polymer stream flow channel splitter devices adapted ~or use in conjunction with runner structures of ~ulti-coinjection nozzle injec ion molding machines. The splitter devices include the runner extensions, T-splitters and Y-splitters o~
this inve~tion and embodiments thereof, which split each flow channel for a polymer melt material into first and second branched exit flow channels of substantlally equal length which exit the devices through first and second sets of axially-a:Ligned spaced, exit ports, each set being located in a different surface portion of the device for communication with corresponding polymer stream flow channel entrances in a runner block of the machine. Preferred embodiments of he T
and Y-splitters are cylindrical in shape, wherqin the flow channels enter the devices radially and transaxially and their first and second branched exit flow channels ex~end in opposite directions and exit the device throu~h exit ports at . ~ _ ~;25~

an angle greater than 90 .relative to the ~low channel from which they are split. In the preferred runner extension the flow channels enter axially into the rearward end of the device in a spread quincuncial pattern, and proceed to the forward end portion of the device where the flow channels are split at axially-spacsd branched points into first and second branched exit flow channels of equal length, which proceed in opposite directions and exit the device through a set o~
axially-spaced first exit ports in one surface portion of the device, and a set of axially-spaced exit ports in another surface portion, about 180 removed from the fir~t exit ports~ The splitter devices include isolation means preferably in the form of expandable piston rings for isolating the polymer flow streams from one another as they enter and exit the device.

Thi~ invention also includes free-floating, force co~pen~ating apparatus and methods for a multi-coinjection no~le injection molding machine. Runner means are mounted preferably on its axial center line, on support means by mounting means in a manner which enable-q the runn~r means/
including the runner block and the runner extension, to ~loat or thermally grow axially and radially on the support mea~s while the machine is in operation. Means, preferably hydraulic are included for providing a forward force to the runner means su~ficient to offset any rearward force from : axial floatation due to injection back pressure, and sufficient to provide and maintain an ef~ective pressure contact seal between the co-injection nozzle sprue faces and the cavity sprue faces during operation of the machine. A
gap is provided betwean the runner block and runner extension and adjacent structure to allow for their floatation and to prevent loss of heat to the adjacent structure.

The apparatus of the present invention further comprises a multi-nozzle machine for making multi-layer injected articles in.which each nozzle co-injects at least three polymer streams and in which the polymeric material for _ ~; _ 62~

each corresponding stream is furnished to each of the nozzles in a separate, substantially equal and symmetrical flow path. The purpose and function of this flow path system is to ensure that each particle of a particular material for a particular layer of the article to be formed that reaches the central channel of any one of the nozzles has experienced substantially the same length of flow path, substantially the same change in direction of flow path: substantially the same r~te of flow and cbange in rate of flow, and substantially the same pressure and cnange of pres ure as is experienced by each corresponding particle o the same material which reaches any one of the remainin~ nozzles. This simplifies and facilitates precise control over the flow of each of a plurality of materials to a plurality of injection nozzles in a multi-cavity injection apparatus.

The appa~atus of this invention further includes the use of.valve mean~ with fewer polymer melt material displaceMent means than there are layers in the article to be formed, whereby one displacement means; displaces material ~or t~o layers, and the valve means partially blocks one of the nozzle orifices for one of the two layer materials and thereby controls the relative flows of the two layers.

The present invention provides improved methods of injection molding a multi-layer article having at least three lay~rs ancl praferably having a side wall. In a preferred method, the valve means i5 moved in the nozzle means of the present invention to a first positlon to prevent flow of all polymer streams through the central channel of the nozzlel The valve means is then moved to a second position to permit the ~low of a first polymer stream through the nozzle centEal channel. In a preEerred embodiment, this first polymer stream will form one of the surace layers of the injection molded article, preferably the inside surface layer. The valve means is moved to a third posi~ion to permit continued flow of the first polymer stream and to permit flow of a second polymer stream into the nozzle central channel. In a preferred embodiment, this second polymer stream will form the other surface layer of the injection molded article, preferably the outside surface layer. The valve means may be moved, as just described, to permit the first polymer stream to begin to flow before the second polymer stream.
Alternatively, flow of the first and second polymer streams may be commenced substantially simultaneously, meaning that the flows begin either at the same time or that a small time interval may 2Xi5t after commencement of flow of the first polymer stream and before commencement of flow of the second polymer stream, or ~ice versa. Each of the alternatives is intended to be encompassed by movement of the valve means to the second and third positions. The valve means is then moved to a fourth position to permit continued flow of the first and second polymer streams, and to permit flow o a third polymer st~eam into the nozzle central channel between the first and second streams. ln a pre~erred embodim~nt, the third polymer stream will form an inte~nal layer in the injection molded articLet betwe2n the inside ~urface layer and the outqide surfa~e layer. Precise and repeatable control of the flow of at least those three polymer stream~
through the cenlral channel of each nozzle employed fa~ilitates continuous, hish-speed manufacture in a multi-nozzle machine of multi-layer, thin wall containers, particularly those in which there is an extremely thin, sub3tantially continuou~ internal layer ~uch a~ an oxygen-barrier layer.

This invention includes methods of forming a plurality of substanti~lly identical multi-layer injection molded plastic articles by injection of a substantially identical stream of polymeric material~ from each of a plurality of co-injection nozzles, by feeding separately to each nozzl~e through the previously-mentioned substantially equal flow path feature, the melt material for each layer of the article to be formed, and substantially simultaneously positively ef~ecting the blocking and unblocking of the nozzle ori:Eices for the melt streams which form corresponding 6~ii7 layers in the articles. Wh:ile tbese corresponding streams are positively blocked and just prior to their being unblocked, they are pressur:ized with a common pressure source. The positive blocking and unblocking is effected with substantially identical valve means driven substantially simultaneously and identically in each co-injection nozzle.

~ his invention includes methods of forming a multi-polymer, multi-layer combined stream o materials in an injection noz~le such that the leading edges of the layers are substantially unbiased, by using the valve means in the central channel for independently and selectively controlling the flow from the orifices in various combinations, including to prevent flow ~rom all of the ori~ices, prevent flow from the orifice for the inte~nal layer or layers while allowing the flow of material for the inner layer fro~ the third ori~ice, for the outer layer from the first orifice or from both of these orifices, and, while continuing ~o allow sald flows, allowing material~s) for ~he internal layer or layers to flow. In addition, the flow through the third orifice may be reduced or prevented, and the flow through the ~econd orifice may be terminated. The above methods can be success~ully employed to form a container who~e internal layer is encapsulated at the bottom of the container with a material for the outer layer which is the same as, interchangeable or compatible with the material for the inner layer.

The methods of this invention include utilizing polymer material melt stream flow directing or balancing means in nozzle flow stream passageways to control the thickness, uniformity and radial position of the layers in the combined stream in the nozzle.

The methods of this invention include ~orming a substantially concentric combined stream of at least three polymeric materials for injec~ion as a shot continuously injected as it is formed into an injection cavity, to form a ~5~;~5~

multi-layer article wherein the combined stream and shot have an outer melt stream layer of polymeric ~aterial for forming the outside layer of the arl:icle, a core melt stream of polymeric material for forming the inside layer o~ the article, and at least one intermediate melt stre~m layer of polymeric material for formi.ng an internal layer of the article, by utilizing the valve means in the co-injection nozzle basically in the manners of the methods described above.

An alternative method of forming such a substantially concentric combined stream for injection as a shot continually injected as it is formed, involves utilizing the valve means in the nozzle means for preventing flow of pol~mer material from all of the orifices, preventing flow of polymer material through the second orifice while allowing flow of structural material through the first, the third or both the first and third orifices, then, allowing flow of polymer material through the 3econd orifice while allowing material to flo~ through the third orifice r re5tricting the flow of polymer material through the ~hird orifice while allowing the flow of material through the second orific~, and restric~ing the flow of poly~er material through the second orifice while allowing flow of polymer material through the irst or third orifices or both the first and third orifices to knit the intermediate layer material with itself through the core ~aterial and substantially encapsulate the intermediate layer in the combined stream and in the shot.

Another method of utilizing the valve means for for~ing an at-least-three layer combined stream in a nozzle involves pr.eventing flow of polymez material through the intermedial:e or internal orifice while ~llowing flow of polymer stluctural material through the first orifice, the third orifi.ce or both the first and third orifices, then allowing flow of polymer material through the second orifice while allowing material to flow through the third orifice, reducing the flow of polymer material through the third ~, ~ ~ ~

~5Ç~

orifice while allowing polymer material to flow through the ~econd orifice, terminating the flow of polymer material through the second orifice, and allowing flow of polymer material only through the first orifice while preventing flow of polymer material from tihe second and third orifices to substantially encap ulate the intermediate polymer material in the combined stream.

Another method included within the scope o~ this invention is injection molding, by use of a multi-coinjection nozzle, multi-cavity injection molding apparatus, an at-least three layer multi-material plastic containex having a sidewall thickness below its marginal end portion of from about .010 inch to about .035 inch, preferably from about .012 inch to about .030 inch.

In the preferred embodiments of this invention wherein an even number of at least four co-injection nozzles are provided in the runner mean~ of this invention, one at each corner o~ a substantially square or rectangul~r pattern, the methods inc;Lude the steps of bringing the separate polymer material streams close to each other in a pattern in ~ubstantially the same horizontal and axial plane wherein they are transaxially offset from each other and axialLy offset just to the rear of and between the four nozzles and directing each flow stream to each of the four respective nozzles.

In the methods of this invention ~herei~ the a~paratus includes eight nozzles, and they are aliyned in a pattern of two rows each having ~our nozzles therein, each of the respective rows being positioned along one of the elongated sides of a rectangular pattern, the steps preferably include bringiAg the separate flow jtream of polymer material into substantially horizontal alignment along a p:Lane centered in the rectangle axially offset and just to the rear of and between the parallel rows of four nozzles, l:hen into horizontally and axially recpectively ~5~25~

displaced alignment, then outward towards the narrow ends of the rectangle to the center of each of the upper and lower patterns of four nozzles, T--splitting at each side center each of the polymer streams into two opposite horizontal streams each of which extends to a point between the point at which the streams were T-split and the respective adjacent two nozzles on either side of the pattern, and, at ~uch latter point Y-~plitting the respective streams into a Y-pattern of diagonal streams, and directing each stream to each of respect1ve co-injection nozzles of the eight co-injection noz~les injection molding apparatus.

Another method of this invention for forming a five ].ayer plastic container having a side wall of the aforementioned thickness comprises, providing a source of supply for each polymer material which is to form a layer of th~ container, providing a means for moving each polymer ma~erial to each of the nozzles, moving each material that is to form a layer of the article from the moving means to the respectiYe nozzles, combining the separately moved materials in each of the respective nozzles, and injecting the combined flow tream through each injection nozzle into a juxtaposed cavity to form the multi-layer, multi-material container.
Still another method of forming such a container having such a side wall thickness comprises, providing a source of supply and a source o~ polymer flow movement for each polymer melt material, channelling each polymer material ~low stream from ltS source of flow movement separately to each nozzle, and providing valve means operative in each of the respective co~injection nozzles and utili2ing the vslve means in each of ~aid co-iniection nozzles in the combining of the separately channelled flow streams.

In preferred practices of the present methods, the production of such containers and other desired containers is greatly enhanced by imparting pressure to at least the third polymer stream prior to, or concurrently with, moving the valve ~esns to the fourth position. In a further preferred practice of the method of the present invention, pressure is al50 imparted to at least one of the first and second polymer streams, and, prior to or concurrent with moving the valve maans to the fourth position, the pressure of one or more of the first, second and third polymer streams is ~djusted so that the pressure of the th:Lrd stream i~ greater than the pressure of at least one of the irst and second streams. In a particularly preferred practic@ of the method of the present invention, pressure is imparted to the first, second and third poly~er streams, and, prior to or concurrent with moving the valve means to the fourth position, the pressure of th~ third polymer stream is increased and the pressure of at least one of the first and second streams is reduced, whereby the pressure of the thir~ polymer stream is greater than the pressure of at least one of the first and second ~treams when the valve means is moved to the fourth p~sition. ~he method of the present invention induces a sufficient initial rate of ~low oP the polymer streams, and p~rticularly of the annular polymer stream (or streams~ which forms an internal layer (or layers) in the injection molded article, substantially uniformly around the circumference of ~he orifice through which the poly~er flows into the central channel of the nozzle.

Thi~ invention includes methods of initiating the flow of a melt stream of polymeric material substantially simultaneously ~rom all portions of an annular passageway orifice into the central channel of a multi-material co-injection nozzle, compri~ing, providing a polymeric melt material i.n the passageway while preventing the material from flowing through the orifice into the central channel ~preferably with physical means such as the valve means of this invention), flowing a melt stream of another polymeric material through the central channel past the orifice, subjectiny the melt material in the passageway to pressure which at all points about the orifice is greater than the ambient pressure of the flowing stream at circumferential positions which correspond to the points about the orifice, 3~
3~

~5~ 7 the pressure being suffici~nt to obtain a si~ultaneous onset flow of the pressurized me]t material fro~ all portions of the annular orifice, and, allowing the pressurized material ~o flow through the orifice! to obtain said simultaneous onset flow. Preferably, the mate!rial pressurized is that which will form the internal layer of a multi layer article injected from the nozzle, the subjected pressure is uniform at all points about the orifice, and the orifice has a center line which is substantially perpendicular to the axis of the central channel. During the allowing step there is preferably included the step of continuing to subject the material in the passageway to a pressure sufficient to establish and maintain a substantially uniform and continuous steady flow rate of material simultaneously over all points of the orifice into the central channel. The subjected pressure is sufficient to provide the snset flo~ of the internal layer material with a leading edge sufficiently thick at every point about its ~nnulus that tbe internal layer in the maryinal end portion of the side w~ll of the artlcle formed i5 at least 1% of th~ total thickness of the side wall at the marginal end portion. These methods can be employed for pre~surizi~g the runner system of a multi-material co-injection nozzle, multi-polymer injection molding machine having a runner system for polymer melt materials which ~xtends from sources of polymeric material di placement to the orifices of a multi-material co-injection nozzle. In pressurizing the runner system, the pressure subjecting step is preferably effected in two stages, first by providing a residual pressure lower than the de ired pressure at which the material is to low through the blocked orifice, and then before or upon effecting tha allowing s~ep, raising the level of pressure to the desired pressure at which the internal Layer material is to flow through the orifice. The pressure raising step may be executed gradually but preferably rapidlyr just prior to or upon effecting the allowing step.

This invention includes methods of prepressurizing 3~
~ ~4 -the runner system of a unit-cavity or multi-cavity multi-polymer injection molding machine fsr forming injection molded articles, ha~ing a runner system for polymer melt materials which extends from sources o~ polymer melt material displacement to the orifice~s of a co-injection noz21e having polymer melt material passageways in communication with the orifices which, in turn, communicate with a central channel in the nozzle, which in some embodiments basically comprises, blocking an orifice with physical means to prevent material in the passageway o~ the orifice from ~lowing into the central channel~ and, while so blocking the orifice, retracting the polymer melt material displacement means, filling the resulting volume in the runner system with polymer melt material from a source upstream relative to the polymer melt material displacement means and external to the - runner system, the amount of retraction and t~e pressure of the polymer melt with which the volume is filled being c~lculated ts be just sufficient to provide that layer's portion of ~he next injec~ion molded article and the pressur~
of the volume-filling melt being designed to generate in the runner system a residual pressure sufficient to increa e the ~ime response of the polymer melt material in the runner system to sub~equent movem~nts of the source of polymer melt material displacement means, and prior to unblocking the ori4ice, displacing the polymer melt material displacement means towards the orifice to compress the material further and raise the pr~ssure in the runner system to a level greater than the residual pressure and suf~icient to cause when the ori~ice is unblocked, the simultaneous onset flow.
These methods can also be effected while the ori~ice is blo~ked, by moving melt material into the portion of the runner system extending to the blocked orifice, discerning the level of residual pressure of the polymer melt material moved into said portion of the runner system, and displacing the melt material in the runner system towards the orifice to compress t]he material and raise the pressure in the runner system to a level greater than the residual pressure and sufficient to cause the simultaneous and preferably uniformly thick onset flow.

~ nother prepressurization method of this invention is for forming a multi-layer plastic article having a marginal edge or end portion, first and econd surface layers, and at least one internal layer therebetween, in an injection cavity of an injection molding machine such ~hat the leading edge of the internal layer extends substantially uniformly into and about the marginal edge or end portion, by applying the aforementioned method of prepressurizing the internal layer material, ~lowing the first surface layer material through the central channel while blocking the internal layer material orifice, flowing the second surface layer material as an annular stream about the first surface layer material, unblocking the orifice, and flowing the prepressurized internal layer material into the central channel into or onto the interface o~ the flowing first and s~cond surface materials ~uch that the internal layer material has a rapid initial and simultaneous onset ~}ow over all points of its orifice and forms an annulus about the flowing first surface layer material between it and ~he second surface layer material, and such that the leadin~ edge o~ the annulus of the internal layer material lies in a plane substantially perpendicular to the axis oE the central channel, and, injecting the combined flow stream of tha inner, ~econd and internal layer materials into the injection cavity in a ma~ner that places the leading edge of th~
internal layer material ~ubstantially uniformly into and about the marginal edge portion of the article. The method can include increasing the rate of displacement of the internal layer polymer melt material as its ori~ice is unblocked to approach and maintain a s~lbstantially steady flow rate of it through the orifice. This method can place the leading edge within the marginal edge or end portion o articles, parisons and containers.

Another method utilizes pressurization for controlling the final lateral location of the internal layer 62~;~

material within the multi-layer wall of an injected parison, by positively controlling the flow and non-flow of the streams which form the outer and internal layers through their orifices by moving the streams past flow balancing means in the nozzle passageways for there selectively and respectively providing desired design flows for each of said streams of polymeric materials, and displacing the respective ou~er and internal layer materials and the inner layer materials through their respective passageways to thereby achieve their respective desired deqign flows, to place the annulu~es of the respective materials uniformly radially in the combining area, and to thereby control the radial location of the internal layer material in the combined injacted material flow stream in the combining area of each nozzle and in each injection cavity. This method can include physically blocking the orifices of the outer and internal layer materials, prepressurizing the outer and internal layer materials in their passageways while their orifices are block2d such that when the orifices are unblocked, the ~ransient times required to reach the desired design flows ~re reduced and the volu~etric flows of ~he outer and internal structural materials into the combining area are controlled~ With respect to this method, a uniform start of the flow of the outer structural material and the internal layer material past all points of its passageway orifice in~o the no2zle central channel can be effected. By practicing these methods, there can be maintained a continuous flow in terms of velocity and volumetric rate of all of the materials during most of the injection cycle. The pressuriæing step can be effected during the displacing ~tep by utili~ing a source of material displacement for subjecting the polymer melt material for the outer layer while it is in its blocked passageway to a first pressure which would be sufficient to cause the ~aterial to flow into the central channel if its orifice was unblocked, and prior to allowing flow of the outer layer material through its orifice, moving the source o polymer displacement and thereby subjecting said outer layer material to a second pressure greater than the first ~C~ 57 pressure and ~ufficient to create, when its orifice is unblocked, a surge of said material and a uniform onset of annular $10w of polymer material over all points of its ori~ice into the central channel when the flow stream i8 considered relative to a plane perpendicu}ar to the axis of the central channel, said second pressure being less than that which would cause leakage of polymer material past the means which ls blocking flow of material into the chan~el, and, during and after the unblocking of the orifice or the material which is to form the outer layer, changing the rate of movement o~ the source of polymer displacement to approach and maintain a desired design substantially steady flow rate of said material through the first orifice into the central channel. This method can also include leaving the ori~ice for the outer structural material unblocked for a time Rufficien~ for effecting and maintaining a continuous, uniform rate and volume of flow of the outer material during 30~ o~ the injection cycle.

This invention includes methods of pressurization which are effected without the use of phyqical means for blocking an orifice, to obtain a substantially uniform onset ~low over the ori~ice. One m~thod comprises subjecting the internal layer material to a pressure equal to or jus~ below the ambient pressure of the matexials flowing in the central channel, and efecting a rapid change in pressure between the pres~ure of that material relative to the ambient pressure, to cause the internal layer material to establish the desired substantially uniform onsst flow.

A method of pressurizing included in this invention involves preventing a condensed phase polymeric material from flowing through an orifice, and prior to allowing the material to flow through the orifice, subjecting the material to a high initial pressure at least about 20% greater than necessary to cause it to flow into the central channel and sufficient to densify the material adjacent the orifice to a density o~ about 2% to about 5% or more greater than ~S~ii7 a~mospheric density. The level of p~epressurization imparted can be greater than, preferably about ~0~ or more higher than the ambient pressure of the materials flowing in the central channel.

This invention includes methods of utilizing pressurization in com~inat:ion with flow directing and balancing means to control the radial location,of an internal layer in the article. A prepressurized material is allowed to ~low at a controlled rate past flow directing means such that the material achieves its desired design flow and places the leading annulus of the material uniformly radially in the combining area of the central channel and in the side wall o~
the injected article.

This invention includes methods of pr~ssurization wherein during and after the unblocking of an orifice of a prepressurized material, the rate of movement of the ram for the ~lowing material is increased to approach a~d maintain a desired design steady flow rate of the material through the orifice into the central channel~

This inven~ion includes methods of providing and .aintaining uniform thickness about and along the annuluses of the materials flowing in the nozzle central channel by subiecting the material in its passageway to a first pressure sufficient to cause the material to flow into the central channel if its orifice was not blocked, subjecting the mat~rial to a second pressure ~reate~ than the first and gufficient to provide substantially uniform onset flow over the orifice, unblocking the orifice to provide an onset flow whose leading edge is in a vertical plane relative to the axis of the central channel, and maintaining the second pressure for preferably from about 10 to about 40 centiseconds to maintain a steady flow of the material into the centr,al channel.
.

'rhis invention includes methods of co-injecting a _ ~1 '7 multi layer flow stream comprised of at least three layers into an injection cavity in which the speed of flow of the layered stream is highest on the fast flow streamline positioned intermediate the boundaries of the layered stream. The methods include establishing the flow of material oX a first layer and the flow of a ~econd layer of the flow ~tream adjacent to the first to form an interface betw~en the flowing materials, positioning the interface at a first location not coincident with the fast flow streamline, interposing the flow of material of a third layer of the flow stream between the first and second layers at a location not coincident with the fast flow streamline, and moving the location of the third layer to a second location which is either relatively more proximate to, or substantially coincident with the fast flow streamline, or which is across from and not substantially coincident with the fast flow ~treamline. The moving of the third iayer to the second location can be effected at or shortly after the interposition o~ the third layer between the ~irst and second laye~s, prefer~bly at substantially all places across the ~raadth of the layer~d stream. The rates of flow of the first and second layer materialq may be selected to position their interface to be non-coincident with the fast flow streamline, and after interposing the flow stream of the ~hird layer in the interface, the relative rates of flow of the first and second layer materials may be adjusted to move the third layer to a loc~tion more proximate to, or substantially coincident with the fast flow streamline, or across the fast flow streamline to a location not coincident with the fast flow streamline. The third layer material may be moved from a fast flow streamline in the central channel that does not correspond to the fast flow streamline, to, relatively more proximate to, or across the fast flow streamline that does correspond to the fast flow streamline in the injection cavity. In the preferred method of this aspect of the invention, the interface is annular ana the interposition of the third layer material is at substantially all places around the circumference of the annular interface.

~562~

This invention includes various methods of preventing, reducing and overcoming bias o portions of the terminal end of the internal layer during the ~ormation of a multi-layer injection blow molded container, which, in certain embodiments involve ~olding over the biased portion of the terminaL end to provide a substantially unbiased overall leading edge of said internal layer, such that the folded over portion and the unfolded portion of the marginal end portion is finally positioned in the side wall of the article in a substantially unbiased plane relative to the axis of the container.

~ he methods of preventing, reducing and overcoming bias include m~thods or preventing, reducing and overcoming time bias and velocity flow bias~

This invention includes injection molded multi-la~er rigid plastic articles, parisons and containers and injection blow molded multi-layer rigid plastic articles and CQntainers, made by the foldover methods of this invention A terminal end portion of the internal layer is folded over within the article, usually w$thin its side wall, and pr~ferably its flange. The foldover can be towards the inslde or outside of the article, parison or container. The container h~ving the folded over internal layer may be open-ended or haYe an end closure or ~le~ible lid ~ecured thereto. Preferably, the leading edge of the internal layer is in a plane which is substantially unbiased relative to the axis of the container. In the containers of this invention, the terminal end o~ the internal layer is more removed ~rom the terminal end of the container than is another adjacent directionally related marginal end portion of the in~ern~l layer. The containers of this invention include those wherein the terminal end of the folded over portion of the internal layer is more removed than the fold line is from the terminal en~d of the container, wherein there is less variation in the distance from the fold line to the terminal end of the container t~an from the terminal end oE the _ ~ _ z:~

internal layer to the terminal end of the container, and wherein the terminal end o:E the internal layar is more removed than the fold line is from the terminal end of the container.

This invention also includes injection molded multi-layer substantially rigid plastic articles including parisons and containers, and injection blow molded multi-layer substantially rigid plastic articles, including containers having slde and bottom walls, and having at least five layers comprised of an outside surface layer, an inside surface layer, an internal layer, and first and second intermediate layers one on either side of the internal layer, wherein the terminal end of the internal layer encapsulated by intermediate layer material, whether it be solely or primarily by first or by both first and second intermedia~e layer material.

Thi~ invention further includes multi-layer injection molded or injection blow m~lded plastic containers whose side wall is compriRed of at least three layers, wherein - the ratio of the internal layer thickness in th~
bottom wall relative to the total bottom walL thickness is on the average greater than the ratio of the internal layer thickness in the side wall relative to the total side wall thickness, - the bottom wall total thickness is less than the side wall total thickness and the thickness of the internal layer in the bottom wall is at least equal to the average thickness of the internal layer in the side wall, - the bottom ~all total thickness is lesR than the total thickness of the side wall, and, in a central portion of the bottom wall, the ~ntern~l layer thickne~s is greater than the average thickne~s of the internal layer in the side wall, or - the average bottom wall total thickness is less than the average side wall total thickness, and at least a portion of the internal layer is thicker in the bottom wall than the average thickness of the internal layer in the side wall.

. . .

~2 ~
Thus, the invention provides methods and apparatus for commercially injec-tion molding multi-layer, substantially rigid plastic parisons and containers, and for commercially injection blow molding multi-layer, substantially rigid plas-tic articles and containers by means of multi-cavity, coinjec-tion nozzle machines.
The invention provides the above methods and appara-tus for so molding said items by means of multi-cavity, multi-coinjection nozzle machines.
The invention provides the above methods and appara-tus for manufacturing the aforementioned articles, parisons and containers on a multi-cavity multi-coinjection nozzle basis, such that each item injected into and formed in each cavity has substantially identical characteristics.
The invention provides injection molding and blow molding methods and apparatus which overcome problems of long runners, variations in temperature within structural compo-nents, variations in temperatures and characteristics of indi-vidual and corresponding polymer melts, and variations in machining tolerances which may occur with respect to multi-layer multi cavity machines.
The invention provides methods and apparatus for providing a substantially equal flow path and experience for each corresponding polymer material flow stream displaced to each corresponding passageway of each coinjection nozzle for forming a corresponding layer of an aforementioned item to be injected.
The invention provides methods and apparatus for preventing bias in the leading edge of the internal layer in the marginal edge portions of the previously mentioned arti-cles, and in the rnarginal end portion of the side walls of the above-mentioned articles, parisons and containers.

,, -- ~1 --~2 ~ ~ 5 ~

The invention provides methods and apparatus for forming such articles, parisons and contalners wherein the leading edges of their internal layers are substantially uni-formly extended into and about their marginal edye portions - and the marginal end portions of their side walls.
The invention provides methods for positioning, con-trolling and for utilizing foldover of a portion of the marginal end portion of said internal layer or layers to reduce or eliminate bias and obtain said substantially uni-formly extended leading edge of the internal layer or layers.
The invention provides methods of avoiding and over-coming time bias and velocity bias as causes of biased leading edges in articles formed by injection molding machines and processes.
The invention provides methods of pressurizing poly-mer melt materials in their passageways to improve their time responses, provide greater control over their flows, obtain substantially simultaneous and uniform onset flows of their melt streams substantially uniformly over all points of their respective nozzle orifices, and obtain substantially simulta-neous and identical time responses and flows of corresponding melt streams of the materials in and through each of the mul-tiplicity coin;ection nozzles of multi-cavity in~ection mold-ing and blow molding machines.
The invention provides separate valve means opera-tive in the central channel of a coinjection nozzle to there block and unblock the nozzle orifices in various desired com-binations and sequences, to control the flow and non-flow of the polymer melt materials through their orifices.
The invention provides aforementioned valve means wherein they are commonly driven to be substantially simulta-neously and substantially identically affected in each coin-. . ' - ~ :

~s~

jection nozzle of a multi-coinjection nozzle injection molding machine.
The invention provides means to control the relative locations and thicknesses of the layers, particularly the internal layer(s) of the previously mentioned multi-layer injection molded or injection blow molded items.
The invention provides methods and apparatus for obtaining effective control of the polymer flow streams which are to form the respec-tive layers of the injected items, in the passageways, orifices and combining areas of coinjection nozzles and in the injection cavi-ties of multi-cavity injec-tion molding and blow molding machines.
The invention provides coinjection nozzle means adapted to provide in coinjection nozzles, a controlled multi-layer melt material flow stream of thin, annular layers sub- ::
stantially uniformly radially distributed about a substan- .
tially radially uniform core flow stream.
The inventlon provides runner means for a multi-cavity multi-coinjection nozzle injection molding machine, which splits each flow stream which is to form a layer of each- 20 injected item, into a plurality of branched flow streams, and directs each branched flow stream along substantially equal paths to each coin;ection nozzle.
The invention provides the aforementioned runner means which includes a polymer flow stream redirecting and feeding device associated with each coinjection nozzle for redirecting the path of each branched flow stream for forming ; a layer of the it:em to be injected, and feeding them in a staggered pattern of streams to each coinjection nozzle.
The invention provides an apparatus for multi-layer multi-coinjection nozzle injection molding machines, including floating runner means and a force compensation system, for , ~5~5~
compensating for injection back pressure and maintaining an on-line effective pressure contact seal between all coinjec-tion nozzles and all cavities of the machines.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a front elevational view of an open ended plastic parison of this invention;
Figure lA is a vertical section taken along line lA-lA of Figure 1;
Figure 2 is a front elevational view of an open ended plastic container of this invention;
Figure 2A is a front elevational view partially in vertical section and with portions broken away, showing the container of Figure 2 having an end closure double seamed thereto;
Figure 3 is an enlarged horizontal section taken along line 3-3 of Figure 2A;
Figure 4 is an enlarged view of a vertical section taken through a portion of the bottom wall and side wall of the container of Figure 2A;
Figure 5 is a schematic enlarged vertical section as might be taken through a marginal end portion of the container of Figure 2;
Figure 6 is a schematic enlarged vertical section as might be taken through another marginal end portion of the container of Figure 2 wherein the marginal end portion of the internal layer or layers folded over toward the outside of the container;
Figure 7, a schematic enlarged vertical section sim-ilar to F'igure 6, shows another embodiment wherein the marginal end port:ion of the internal layer or layers is folded --' _ 4~ _ .: . . - . . . : ~

~5~2~i~

over toward the inside of the container;

~ . ',' : 20 ,~
~: - 45 -- ' ' Figure 8 is a schematic view of an enlarged vertical section as might be taken through a container of this invention with layers not shown and with letter designations representing the container'~i overall dimensions.

Figure 8A is an en:Larged schematic vertical section with layers not shown and w:ith portions broken away, of the bo~tom of a container of this invention.

~ igure 9 is an enlarged vertical section through a mar~inal end portion of a container of this invention having an end closure double seamed thereto.

Figures 9A through 9D are enlarged vertical sections ~hrough various embodiments of multi-layer plastic containers Oe this invention whose marginal end portions have an end closure double seamed thereto.

Figure 9A shows the marginal end portion of the internal layer or layers folded over in the flange toward the outside of the container~

Figure 9B shows the marginal end portion of the internal layer or layers folded over in the flange toward the inside of the container.

Figure 9C shows the marginal end portion of the internal layer or layers in the arcuate portion o~ the top end o the container side wall, folded over toward the outside of the container.

EPigure 9D shows the marsinal end portion of the internal layer or layers in the marginal end portion of the container side wall near the bottom of the double seam, folded ove~r toward the outside of the container.

Figures 10 and lOA show enlarged vertical sections through embodiments of the multi-layer plastic containers of .

~ ~ 56 ~37 this invention having a flexible lid sealed to the container flange.

Figure 10 shows the marginal end portion of tbe internal layer or layers in the flange folded over toward the inside of the container.

Figure lOA shows the marginal end portion of the internal layer or layers in the flange folded over toward the outside of the container~

Figure 11 is a top plan view of an inj ction blow molding line which includes apparatus of this invention.

~ igure 12 is a side elevational view of the injection blow molding line of ~Pigure 11.

EPigure 13 is an elevational view of a portion o~ the apparatus with portlons omitted, a~ woult be seen aloag line 13-13 of ~igure 11 or of Figure 9S.

Figure 14 is a top schematic view, with portions broken away and portions in horizontal cross-section at different levels, showing the right por~tion of the apparatus o~ Figure 11.

~ Pigure 15 is an elevational view basically as would be seen along line 15-15 of Figure 14.

~ igure 16 is a vertical section taken along line 16~16 of Figure 15.

Figure 17 is a vertical section taken along line 17-17 of E`igure 14.

~ 'igure 18 i~ a side elevational view taken along line 18-18 of Figure 17.

Figure 18A i5 a side elevational view taken along line 18A-18A of Figure 18.

Figure 19 is an elevational view with portions in section, taken along line 19-19 of Figure 17.

Figure l9A is an elevational view with portions in section, taken along line l9A-19A of Figure 17.

Figure 20 is a perspecti~e view, with portions broken away, of the runner extension shown in Figure 14.

Figure 21 is an enlarged top plan view of the runner extension shown in Figure 14.

Figure 21A is an end view of the fo~ward end of the runner extension of Figure 21.

Figure 22 is a vertical section t~ken along l~ne 22-22 of Figure 21.

Figure 23 is a vertical section taken substantially along line 23-23 of Figure 21.

Pigure 24 is a vertical section taken substantially along line 24-24 of ~igure 21.

Figure 25 is a vertical section taken substantially along line 25-25 of Figure 21.

Figure 26 is a vertical section taken substantially along line 26-26 of Figure 21.

Figure 27 is a vertical section taken substantially along line 27-27 of Figure 21.

Figure 28 is a vertical section taken substantially along li:ne 28-28 of Figure 21, but additionally sbown witbin ,~
. ~ _ a vertical section (with ;portions broken away) of the runner block of this invention.

, Figure 28A is an enlarged perspective view of another embodiment of the runner extension of this invention.

Figure 28B is a vertical section taken along line 28~-28B of Figure 28A.

Figure 28C is a vertical section taken along line 28C-28C of Figure 28.

Figure 28D is a vertical section taken along line 28D-28D of Figure 28.

Figure 28E is a vertical sec~ion takan along line 28E-28E of ~igure 28.

Figure 28F is a vertical cection taken along line 28F-28F of ~igure 28.

Figure 28G is a horizontal diametrical section with portions broken away, taken substantially along a line represented by 28G-2BG of Figure 280 Figure 28~ is a vertical section with portions broken away taken along line 28~28~ of Figure 2~.

Figure 28I is a perspective view o another embodiment of the runner ex~ension of this invention, shown par-~ially in phantom within a portion of a runner block, also shown in phantom.

Figure ~8J is a vertical section with portions brok~n away showing the runner extension embodiment of Figure 28I within a portion of a runner block of this invention.

Figure 28K is a perspective view of the runner ~Y

5~

extension embodiment of Figure 28I and 28J.

Figure 29 is a front view partially in elevation, partially in vertical section (with section lines not shown for clarity), and with portions broken away, taken substantially along line 29-29 of Figure 98.

Figure 29A is a front elevational view of the runner block of this invention having eight co-injection nozzles mounted therein, as would be seen in Figure 98 with the injection cavity bolster plate 950 and its attached structure removed.

Figure 29A' is a vertical section taken along line 2gA'-29A' of Figure 29A.

Figure 29B is a side elevational view of the runner ~lock of Figure 29~.

Figure 2gC is a front view with portions in elevation, portions in vertical section (with some section lines omitted for clarity) and portions broken away taken through the runner block along line 29C-29C o~ Figure 93.

Figure 30 is a vertical section taken substantially along line 30-30 of Figure 29, showing the forward portion of the apparatus o~ this invention.

]?igure 31 is a top horizontal sectional view taken substantially along line 31-31 of Figure 29, through the second from the bottom nozzle in the left column of nozzles in Figure 2~.

~ Pigure 32 is an exploded perspective view showing the positional relationship in a runner block (not shown) of the runner extension, the T-splitter, Y-splitter, and feed bloc~, as shown in the lower left portion of Figure 29C.

_ ~

Figure 33 is a top plan view of the T-splitter shown in Figures 29, 30 and 32.

Figure 33A is a ~iew of the forward face of the T-splitter of Figure 33.

Figure 34 is a side elevational view of the - T-splitter shown in Figures 30, 32 and 33.

Figure 34A is an elevational view of pins and ~et screw which it within bores in the left side o~ the T-splitter o Figures 33 and 34.

Figure 35 is a vertical section t2ken along line 35-35 o~ Figure 34.

~ Figure 36 is a vertical section tak~n along line -~ 3S-36 o~ Figure 34.
:
Figure 37 is a side elevational view o~ the - Y-splitter shown in Figure 32.

Figure 38 is a top plan view of a ~-splitter having its entrance holes aligned at the six o'clock position.

Figure 39 is a vertical section taken along line 39-39 of F$gure 38.
.

Figure 40 is a vertical section taken along line 40-40 of Figure 38.

Figure 41 is a side elevational view of the feed block shown in Figure 32 rotated to have its inlets aligned at the twelve o'clock position.

Figure 42 is an end view of the forward end of the feed block of Figure 41.

_ 5;7 Figure 43 is a vertical section taken along line 4~-43 of Figure 42.

Figure 44 is an enlarged view with portions broken away as would be seen along line 44-44 of Figure 41.

Figure 45 is a vertical section taken along line 45-45 of ~igure 41.

Figure 45A is an enlarged side elevational view of a plug 154 for bore 152 in the runner block and hole lS8 in the feed block.

Figure 45B is an enlarged side elevational view of another plug 154' similar to plug 154 in Figure 45A but having a larger nose.

Figure 46 is a vertical section ~aken along line 46-46 o~ Figure 41.

Figure 47 is a vertical section taken along line 47-47 of Figure 41. .

Figure 48 is a vertical section taken along line 48-48 of Figure 41.

Figure 49 is a side eleva~ional exploded telescoped view with portions broken away, showing the nozzle shells and nozzle cap components which comprise the preferred nozzie assembly of this invention.

Figure 49A is a perspective view showing the nozzle assembly mounted within the feed block of Figure 41 (shown in - ~ ,..... .
: - . , ~ . . '. :

5~ 57 phantom).

Figure 49AA is an end view o the Dozzle assembly as would be seen along line 4gAA-49AA of Figure 49A.

Figure 50 is a vertical sectional Yiew of the nozzle assembly taken along the various sets of lines 50-50 of Figure 49AA.

Figure 51 is a side elevational view o~ the inner shell of the nozzle assembly.

Figure 52 is a front end view of the inner shell of Figure SO.

Figure 53 is a rear end view of the inner shell shown in Figure 50.

Figure 53A is a vertical section taken along line 53A-53A of Figure 53.

Figure 53B is an enlarged view of the lower right portion of Figure 53A.

Figure 53C is an enlarged view with portions in section, and portions broken away, of the sealing rings shown in Figure 53.

Figure 54 is a vertical section taken along line 54-54 o Figure 51.

~ igure 54A is an enlarged top plan view with portions broken away as would be seen along line 54A-54A of Figure 51 showing the port in the wall of the inner shell.

~ igure 55 is a side elevational view of the third shell of ~he nozzle assembly.

~3 Figure 55A is a vie~ of the ~ront end of the third shell as would be seen along line 55A 55A of Figure 55.

Figure 56 is a vertical section taken along line 56-56 of Figure 55.

- Figure 57 is an end view of the rear face of the third shell as would be seen along line 57-57 of Figure 55.
.
~: Figure 57A is a vertical section taken along line . 57A-57A of Figure 57.
.
Figure 58 is a side elevational view of the second shell of the nozzle assembly.

~ igure S9 is a front end view of the second shell taken along line 59-59 of ~igure 58.

Figure 60 is a vertical section taken ~long line .~ 60-60 o~ Figure 58.

Figure 61 is a vertical section taken along line 61-61 of Figure 53.

Figure 62 is an end view of the rear face of the second shell of Figure 58.

Figure 63 is a vertical section taken along line 63-63 of Figure 62.

Figure 64 is a top plan view with portions broken away showing the port in the upper wall of the second shell of Figure 58, taken along line 64-64 of Figure 63.

Figure 65 is a side elevational view of the outer shell of the nozzle assembly of Figure 50.

Figure 66 is a front view of the outer shell as ~y _ ~ _ would be seen along line 66-66 of Figure 65.

Figure 67 is a vertical section taken along line 67-67 of Figure 65.

Figure 68 is a vertical section taken along line 68-68 of Figure 55.

Figure 69 is an end view of the rear face o~ the outer shell as would be seen along line 69-69 of Figure 65.

Figure 70 is a vertical section taken along line 70-70 of Figure 69.

Figure 70A is a top plan view with portions broken away showing a port in the uppe~ wall of the outer shell of Figure 70, as would be seen along line 70A-70A of Figure 70 Fi~ure 71 is a side elevational view of the nozzle cap of the nozzle assembly og Figure 50.

Figure 72 is a front elevational view of the nozzle cap of Figure 71~

Figure 73 is a vertical ~ec~ion taken along line 73-73 of Figure 74.

Figure 74 is a rear elevational view of the nozzle cap o~ Figure 71.

Figure 75 is a side elevational view of shell 432, Figure 76 is a vertical section taken along line 76-76 of Figure 75, and Figure 77 is a rear elevational view taken along line 77-77 of Figure 75, each of Figures 75, 7S and 77 showing ]etter designation~ ~or the dimensions of common structural features for each of the shells and cap of the noz~le assembly, for use with Table I.

~25~ 57 Figure 77A is an enlarged veltical section with portions broken away, taken through a forward portion of a co-injection no%zle embodiment of this invention, showing orifice center lines perpendicular to the axis of the nozzle central channel.

Figure 77B is a schematic drawing representing a portion of shells of a co-injection nozzle showing dimensions thereof which are used in calculations to provide data shown in the Tables for Figure 77B.

~ igure 78 is a side elevational view o~ a preferred embodiment of the hollow sleeve of the preferred valve means of i~his inventiQn.
:
Figure 79 is a ront elevational view of the sleeve o~ Figure 78.

Figu~e 80 is in:part a vertical section taken along line 80-80 of ~i~ure 79, and ln part a Yertical section taken ; along line 80-80 o~ ~igure 78.

~: Figure 81 is a side elevational view of the : prefer~ed isolid shut-off pin of the pre~erred valve means o~
: this invention which cooperates with the sleeve of Figure 81 and the nozzle assembIy o~ ~igure 50.

Figure 82 is a side elevational view of the solid pin shuttle of this invention.

Figure 83 iis a rear elevational view of the solid pin shuttle of Figure 82.

~ igure 84 is a fron~ elevational view of the solid pin shuttle o~ Figure 82.

Figure 85 is a side elevational view of the solid pin cam bar which cooperates with the solid pin shuttle of .~6 i?..,~

Figures 83-85.

Figure 85A is a top plan view as would be seen along line 85~-85A of Figure 85.

Figure 86 is an exploded perspective view of the solid pin, and solid pin shuttle and solid pin c:am bars of Figures 83-85A.

Figure 87 is a perspective view of the solid pin in the solid pin shuttle in turn mounted within the pair of solid pin cam bars shown in Figure 86.

Figure 88 is a top plan view of the sleeve shuttle of this inv@ntion.

Figure 89 is a side elevatisnal view of ~he solid pin shuttle of Figure 88.

Figure 90 is a ve~tical section taken along line 90-90 of Figure 88.

Figure 91 is a vertical section taken along line 91-91 of Figure 88.

Figure 92 is a front elevational view of the solid pin shuttle of Figure 88.

Figure 93 is a side elevational view with portions broken away oE the sleeve cam bar upon which is mounted the sleeve shuttle of Figures 8~-92.

Figure 93A is a plan view of the bottom o the sleeve cam bar as would be seen along line 93A-S3A of Figure 93 .

Figure 94 is a front elevational view of a portion of the sleeve cam bar as would be seen along line 94-94 o~

~7 ~i6?~

Figur e 9 3 .

Figure ~5 is an exploded perspective view with portions broken away or the two halves of the sleeve shuttle positioned one on either s:ide of the sleeve cam bar o~ Figure 93.

Figure 96 is a perspective view with portions broken away and portions exploded showing the sleeve shuttle mounted onto the sleeve cam bar, with the sleeve ready for mounting onto the huttle.

Figure 97 is a vertical section with portions broken away as would be taken through the nozzle shut-off acsembly, and through the sleeve and shuttle components, showing the mounting and relationships of the sleeve, its shuttle, and the pin and its shuttle.

Figure 98 is an enlarged schematic top plan view with portions broken away showin~ the front portion of a pre~erred embodim~nt of the multi-layer multi-cavity injection machine o~ this invention.

Flgure 93 is a view with portions in vertical s~ction, in front elevation and with portions broken away, as would be seen along line 99-93 of Figure 98.

Figure 100 is a view with portions in vertical section, in side elevation and with portions such as transducers not shown, as would be seen substantially along line 100~100 of Figura 38.

Figure 101 is an enlarged vertical section with portions broken away and portions shown in side elevation, of a portion of Figure 30, showing the sleeve and pin mounted on their shuttles and on their respective cam bars in the nozzle shut-off assembly.

i, Figure 102 is a horizontal section with portions shown in top plan view as would be seen substantially along llne 102-102 of Figure 101.

Figure 103 is a front elevational view with portions in vertical section and portions broken away, as would be seen substantially along line 103-103 of Figure 98 Figure 104 is a front elevational view wlth portions shown in vertical section and portions broken away, as would be seen substantially along line 104-104 of Fi~ure 101.
., Figure 105 is an enlarged front elevational view as would be seen of a portion of Figure 104 with the pin shuttle and pin cam bars removed.

Figure 106 is an enlarged perspective view with portions broken away, portions in cro~s-section and portions in phantom, showing alternative valve means mounted in a nozzle shell, and alternative drive means of this inventlon. - , .~ .
Figure 107 is an enlarged perspective view with portions broken away and portions in cross-section showing 25 alternative valve means mounted in the c~ntral channel of a nozzle shell, and alternative drive means of this invention.

Figure 108 is an enlarged perspective view with portions broken away and portions in cross-section showing alternative valve means of this invention~

Figure 109 is an enlarged perspective view with portions broke away and portions in cross-section showing an alternative embodiment of valve means mounted within the central channel of a nozzle shell.
-.
~ _ 59 _ :, , , .

:. . , -'' ~ ' ' ': , Figure 110 which appears on the same sheet as Flgure 106, is a perspective view with portions broken away and portions in cross-section showing another embodiment of valve means mounted within the central channel of a nozzle shell, and of alternative drive means of this invention.

Figures 111 through 11l6 are enlarged vertical sections with portions broken away and portions shown in side elevation take~ through the forward portion of a preferred embodiment of co-injection nozzle means of this invention wherein the valve means includes a fixed pin. Fi~lre 111 shows the first position - or mode of the sleev~, Figure 112 shows the second, Figure 113 the third, Figure 114 the fourth, Pigure 115 the fifth and Figure - 116 the sixth position or mode of the sleeve in an in~ection - 15 Cycle.
Figure 117 while appear on the same sheet as Figure 108, is an enlarged exploded perspective view with portions shown in section, portions broken away and portions shown in phantom, showing still another embodiment of the valve means and drive means of tAis invention.

Figure 118 is an enlarged perspective view with portions in vertical section and portions broken away, showing the forward portion of another embodiment of co-in~ection nozzle means of this invention.

Figure 118A is an enlarged schematic vlew with portlons in vertical section, portions in side elevation and portions broken away showing a portion of an alternative nozzle assembly of this invention.

Figure 118B is an enlarged perspective view with portions shown in vertical section, in side elevation and portions broken away, showing alternative valve means in the form of a stepped sleeve and modified pin nose.

.
., :.
..
', ' . . ' - ', .

.

t~t7 Flgure 118C is an enlarged schematic view with portions in vertlcal section, portions ln side elevatlon and portions broken away showing an embodlment of the co-in~ection nozzle assPmbly havlng modified passageways and orifices for internal layer materials.

- 60a -~2S~5~

Figure 118C is an enlarged schematic view with portions in vertical section, portions in side elevation and portions broken away showing an embodiment of the co-in~ection nozzle assembly having modified passageways and orifices for internal layer materials.

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~ . ,; '. ',' . , ' :

: -. ' ' ' . - ' ~.~S~2~ ~1 Figure 118D is a schematic plot o pressure in the combining area of a co-injection nozzle without valve means, as a function oP time.

Figure 118E is a schematic plot of pressure in the combining area of a co-injection nozzle with valve means, as a function of timeO

Figure 118F is a schematic plot showing pressure as a function of injection cycle time without the benefit of the valve means of this invention~

Figure 118G is a schematic plot of pressure versus injection cycle time with the benefit of the valve means of this invention.

Figure 119 is a schematic view with portions shown in horizontal section and portions broken away, showing the le~t-hand portion of the apparatus of this invention which provides the e~ective pressure contact seal between the injection cavity sprue and nozzle ori~ices of this invention.

Figure 120 is an enlarged ~ide elev~tional view with portions shown in section and portions broken away, of the apparatus of Figure 119.

Figures 121 through 126 are enlarged schematic Vi@WS
with portions in vertical section and in side elevation, and with portions broken away, showing the preferred selected positions or modes of the preferred valve means of this invention. Figure 121 shows the first mode, Figure 122 the secon~, Figure 173 the third, Figure 124 the fourth, Figure 125 the fifth and Figure 126 the si~th modeO

Figure 127 i5 a plot of melt pressure versus ~ime showing a relatively slow rate of buildup of pressure of the C layer material.

ii7 Figure 128 i5 a plot of melt pressure versus time with a relatively increased rate of pressure buildup of the C
layer material.

Figure 129 is a plot of the melt pressure of five polymer flow streams of this invention as a function of time for the eight cavity injection machine of this invention.

Figures 130 through 137 are enlarged schematic vertical sectional views of the forward portion of a co-injection nozzle assembly in communication with an injection cavity sprue, showing the foldover injection method of this invention. Figure 131 shows time bias in the initial flow of C layer material, Figure 132 the C layer material moved across the fast flow streamline, and Figure 133 the marginal end portion of the C layer material folded over within a flow stream moving into the injection cavity sprue.

Figure 134 shows the polymer melt material moving up into the cavity.

~ igure 135 shows the leading edge of the folded over internal layer in the flange of the injected parison and with substantially no axial bias.

Figures 136 ànd 137 show another application of the foldover method of this invention.

Figure 138 is a plot of the position of the tip of the pin and sleeve as a function of time, relative to a reference point designated 0 in Figure 124.

~ igure 139 is a ~raph schematically plottlng a melt flow rate of polymer material into an injection cavity, as a function of time.

Figures 139A through 139E are schematic diagrams, not drawn to scale and with portions exaggerated for - ~0 - ' ~ `3~

illustrative purposes, illustrating the effects of pressure with time upon a polymeric melt material in a passaqeway at its orifice prior to, upon, and after opening of the orifices.

Figure 133F is a plot of compressibility versus pressure for high density polyethylene at about 400E., illustrating the effect of pressure upon response time of the material.

Figure 140 is a flow chart showing the sequence of operations of the tasks performed in accordance with this invention, relative to an injection cycle.

Figure 141 is a general block diagram of the control system used in accordance with the sequence of Figure 1400 Figure 142 is a graph of command voltages versus time for each servo.

Figure 143 is a pressure diagram resulting ~rom the servo commands of Figure 142.

Figure 144 is a block diagram o~ the principal control circuit boards used in ~igure 141 for injection/recharge control.

Figure 145 is a signal input circuit used in conjunction with this invention.

Figure 146 is a detail of the servo loop circuitry.

Figure 147 i9 a flow chart in two vertical columns of the program employed in conjunction with the injection/recharge processor unit.

Figure 148 is a memory map showing the location of items in the memory of the distributed proressors employed in conjunction with this invention.

~3 56~:5i7 DETAILhD DESCRIPTION OF ~E INVENTION

The Article The multi layer injection molded article or structure produced by the pr~asent invention may be in the form of a container, shown as a parison 10 in Fig. 1 and in the cross-section shown in Fig. lA. The parison has a wall 11 with a mar~inal end portion 1~, terminating in a outwardly-extending flange 13. In a preferred embodimen~, the parison is of a size to form a 202 x 307 blow-molded container which when double seamed would have a nominal diameter of 2-2~16 inches and a nominal height of 3-7/16 inches. Parisons of other sizes and shapes to for~
containers having the same or other dimensions are included within the scope of this invention. In the preferred embodiment, shown in ~igs. 1 and lA, the parison w~ll 11 is comprised of five co-injected layers 14 18 of polymeric ma~erials. For purposes of the description herein, the inside layer 14~ referred to as layer A, is formed of polymer A and may also be referred to as the inside structural or surface lay~r, inside layer or inner layer. The outside layer 15, referred to as layer B, is formed of polymer B, and may also be referred to as the outside structural or surface layer, outside layer or outer layerO Polymer ~A~ may be the same material as polymer "B~. Internal layer 16, referred to as layer C, is formed of polymer C, and may also be referred to as the internal layer or the buried layer. There may be one or more layers between layer A and layer C, and between layer B and layer c. Such layers may perform one or more of the functions of being adhesives or being carriers for other materials such as drying agents or oxygen-scavenging compounds. In the preferred embodiment, layer 17, located between layers A and C aRd sometimes referred to as layer D, is formed of polymer D, and may also be re~erred to as an intermediate or as an adhesive layer. Similarly, layer 18, located between layers B and C and sometimes referred to as layer E, is formed of polymer E, and may also be referrea to ~5~57 as an intermediate or as an adhesive layer. Polymer "D" may be the same material as polymer ~En. The multi-layer parison wall 11 may be comprised of three layers A, B and C. In a five layer embodiment, the layers 16, 17 and 18 may be referred to in combination as the internal layers or buried layers.

The articles, parisons and containers which can be formed in accordance with this invention are thin, and are preferably very thin.

The thicknesses in in~hes of layers A, B, C, D and E
in parison 10 at the base 13' of flange 13, at approximately mid-length 19, at a location 20 closer to the bottom of the parison a`nd at location 38 still closer to the bot~om are as follows. Flange 13: A 0.0095; B 0.0113; C 0.0010; D 0.0005;
E 0.0022. Mid-length 19: A 0.0350; B 0.0375; C 0.0028; D
0.0027; E 0.0030. Location 20 close to bottom: A 0.0396;
B 0;9508; C 0.0040; D 0.0020; E 0.0026. Location 38 elose to bottom: A 0~0363; B 0.0346; C 0.0073; D 0.0009, E 0.0009.
The overall length of parison 10 is about 3 inches including the length of qprue 40.

The multi-layer, injection molded or blow-molded articles produced by the present invention may be in tbe form of the containers as broadly meant and represented by the parison embodiments shown in ~ig~. 1 and lA, and in the form of the containers represented by the embodiments shown in Figs. 2 through lOA. Each o~ the containers 22 and 23, 50 and 56-62, and 68 has a multi-layer wall 25 having ide wall 26 and bottom wall 27 portions. Side wall 26 has a marginal end portion 28 terminating in a ~lange 29. The lower portion of side wall 26 has an outwardly-extending contour 32. This contour tends to protect side wall labels (not shown) and enables tlle container to roll in processing equipment.

t:omparing parison 10 with tAe finished containers, flanges 1:3 and 29 and the upper parts of the marginal end - ~3 -.5~

portions 12 and 28 are not substantially changed when the pari on is 1nflated and are essentially formed in the injection process. The remaînder of the multi-layer parison wall is stretched and thinne~l in the blow-molding process.
In a preferred container such as designated 23 in Fig. 2A, inflated from a parison having approximately the thicknesses stated above, the thicknesses in inches of layers A, B, C, D
and E at approximately mid-length 30 o~ side portion 26 ~roughly corresponding to parison location 19), at lower portlon 31 of side portion 26 (roughly corresponding to parison location 20) and at bottom portion 27 (roughly corresponding to parison location 38) are as follows.
~id-length 30 A 0.0165; B 0.01777 C 0.0013; D 0.0013;
E 0.0014. Lower portion 31: A 0.0120 B 0.0154; C 0.0012.;
D 0.0006; E 0.0008. Bottom portion 27lo A 0.~085; ~ 0.0081;
C 0.00177 D 0.0002; E 0.0002.

When the containers of the present invention are used for hot-filled food products, it is preferred that the thickness of the ~ide wall be substantially uniform from the flange to the bottom radius 36, and that the bottom wall 27 be thinner than the sid2 wall. ~aving the bottom wall thinner will cause it, rather than the side wall, to bow inwardly upon cool-down of the sealed, hot-filled container~
Dimension for the bottom of a retortable container of the same size would be different.

Broadly, the present invention has utility with respect to materials which exhibit laminar flow which is important in maintaining the separateness of the layers of the materials in the injection nozzle central channel and in the injection cavity, as will be more fully described below.
Materials and process conditions which lead to turbulent flow or to other. forms of flow instability, for example melt fracture, are undesirable~ The materials described below are, for the most part, polymers which form melt material flow streams at the con~itions of eleva~ed temperature and pressure which are preferred in the practice of the present ~ s~
invention. Those skilled in the art having read the present specification will appreciate that other equivalent materials may be used. The materials preferably are a].so condensed phase materials, that is, they do not foam when the material is not under pressure.

In a preferred embodiment, the polymers of structural layers A and B are polyolefins or blends of polyolefins, the polymer of internal layer C is an oxygen-barrier material, preferably a copolymer of ethylene cmd vinyl alcohol, and the polymers of internal layers D and E are adhesives whose function is to assist in adhering polyolefin layers A and B to the ethylene vlnyl alcohol, oxygen-barrier layer C.

When the injection molded and in~ection blow molded article is to be used as a container for oxygen-sensitive food, the preferred polymeric material for each of the structural layers A and B is a polyolefin blend of 50 ~ by weight of polypropylene homopolymer ~Exxon Inc. PP. 5052 ; melt flow rate f 1.2) and 50% by weight of high density polyethylene ~DuPont Alathon 7~20; 0.960 density and a melt indiex 0.45); the preferred polymeric material for layer C is a copolymer of ethylene and vinyl alcohol ("EVOH") (Kuraray EVAL-EPF ; melt index of ~.3), which functions as an oxygen-barrier layer; and the preferred polymeric material for layers D and E is an adhesive comprising a modifled polypropylene ln which maleic anhydride is grafted onto the polypropylene backbone (Mitsui Petrochemical Ind., Ltd., Admer-QB 530 ; melt flow rate of 1.4).
Containers have been made from these materials and in which, per container, there is 0.616 gram EVOH, 0.796 gram of adhesive and 11.02 grams of polyolefin blend. The weight of blend ln the inside A structural layer is about 5.40 grams; in the outside B
structural layer, about 5.62 grams. The weight of adhesive in layer E is about 0.46 gram; in layer D, about 0.34 gram.

The principal requirements for the material of ~ ~-'~ - , . . ' .
.
.

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structural layers A and B are impact resistance, low moisture vapor transmission and a des.ired high degree of rigidity.
Depending upon the desired end use of the container, alternative materials for the structural layers include high density polyethylene, polypropylenes, other blends of polypropylenes and polyethylenes, low density polyethylenes where a flexible container is desired, and polystyrenes, polyvinylchloride and thermoplastic polyesters such as polyethylene terephthalate or its copolymers. Suitable copolymers of polyethylene terephthalate are those in which a minor proportion, for example up to about 10% by weight, of the ethylene terephthalate units are replaced by compatible monomer units in which the glycol moiety of the monomer is replaced by aliphatic or alicyclic glycols. These suitable copolyesters based on polyethylene terephlhatate are g~nerally prepared from terephthalic acid or its acid forming derivatives and ethylene glycol or its ester forming derivatives. They can be prepared from the condensation polymerization of a single diacid and two diols, or sf two diacids and a single diol. Examples are glycol modified polyethylene terephthalate, referred to as PETC, ma~e from dimethyl terephthalate, ethylene glycol and cyclohexane dimethanol, and one referred to as PTCA, made ~rom dimethyl terephthalate and dimethyl isophthalate and cyclohexane dimethanol. Those skilled in the art will select appropriate and suitable materials depending on the end use of the product. Por instance, although homopolymers af polypropylene by themselves may be too brittle when the article is to be used at low temperatures, suitable copolymers and impact modified grades of polypropylene may be ~mployed. The structural layers may contain fi]lers, such as calcium carbonate or talc, or pigments, such as titanium dioxide.

Internal layer C forms the desired barrier, whether for oxygen or another gas or moisture or other barrier properties such as a barrier to radio frequencies. When oxygen barrier property is desired and the packaged product bg - ~6 -~2 ~
has high oxygen sensi-tivity, EVOH is the preferred material for lay~r C. High oxygen barrier property may be attained with a very thin layer of ~OH, on the order of about 0.001 inch thickness, which, in view of the relatively high cost of EVOH, is quite important ~rom the economic standpoint of cost-effectiveness. The present invention provides for continuous, high-speed manufacture of multl-layer container~ having such a thin layer of ~VOH which is substantially continuous throughout the wall of the container. Where oxygen sensitivity o~ the packaged product exis-ts, but is relatively low, other oxygen-barrier materials such as nylon, plasticized polyvinyl alcohol and polyvinylchloride may be used. Although most acrylonitrile and polyvinylidene chloride copolymers as currently produced probably would not be suitable, with appropriate modifications it is contemplated these might be employedO For certain packaged products a foam may be employed as an internal layer.

Adhesive layers D and E are preferably formed o~ the above-described maleic anhydride graft polymer when the barrier layer C material is EVOH and the material of the adjacent structural layer is polypropylene or is a blend of polypropylene and high density polyethylene. When high density polyethylene forms a structural layer ad;acent an EVOH barrier layer, an adhesive between them may be employed in accordance with the teachings of the aforementioned U.S. Patent Nos. 4,525,134 and 4,526,821. Those Patents disclose that a suitable adhesive for use with structural layers of polypropylene-polyethylene block copolymers, is a blend of ethylene vinyl acetate copolymer and a graft copolymer. They also disclose that a suitable adherent is the aforementioned blend wherein the graft copolymer is of high density polyethylene and a fused ring carboxylic acid anhydride.

As mentioned, EVOH is a relatively expensive material and, therefore, when it is employed as the polymer for oxygen-barrier layer C, it is highly desirable to keep ~ S ~2 ~ ~

the thickness of the layer to the minimum needed to impart oxygen-barrier propcrty to the container~s wall. The present invention facilitates reliable, high-speed manufacture of con-tainers having an oxygen-barrier layer C as thin as 0.001 inch or less and which is substantially continuous throughout the wall and is substantially completely encapsulated by the inside and outside layers ~ and B.
When layer C is an EVOH oxygen-barrier polymer, its barrier properties may be protected against moisture-induced degradation by the incorporation of a drying agent into one or more of the layers, as is more fully described in Farrell et al, United States patent No . 4,407,897, issued October 4, 1983. Further, one or more of the layers may incorporate oxygen-scavenging material, as is more fully described in Farrel et al, United States patent No . 4,536,409, issued August 20, 1985 and U.S. patent No . 4,536,410, issued January 10, 1984.
In the preferred injection molded articles and injection blow-molded articles, the internal layer 16 and all internal layers are substantially conti.nuous and substantially completely encapsulated within the outer layers 1~,15. Most preferably, there are no discontinuous or holes in the inter-nal layer or in the encapsulating layers, and the terminal end 33 (Fig. 5) of the internal layer (sometimes referred to here-inafter as the leading edge of the internal layer or buried layer) extends sufficiently into the marginal end portion 12, 28 of the side wall 11, 26 of the parison and container, respectively, such that when the article is covered or sealed, the terminal end of the internal layer material is included within the cover or seal area, whereby there is a relatively long path through the wa~l of the article for permeation of unwanted material, e.g., gas. In a flanged container which is to be double ~5~2~

- 70a -~5~i2~;~

seamed, the most pre~erred embodiment is one wherain the terminal end of the internal layer extends into the flange and the location of the terminal end is uniform about the circumference of the flange. For the pres0nt purposes, the term uniform encompasses a variation of about plus or minus .030 inch. ~lso, in the most preferred embodiment, the terminal end of the internal layer extends to at least half of the length o the flange. An acceptable container is also obtained when the terminal end of the internal layer extends to the base o~ the flange, such that when the double seam is formed, as shown in Fig. 9C, a portion of the double seam sufficiently overlaps the end portion 28 o~ the container side wall which contains internal layer that there remains a relatively long travel path for permeation of an unwanted material through the side wall structure. The less need there i~ for a completely continuous and completely encap~ulated internal barrier layer, the more tolerable will be a lower reaching terminal end, non-uniformity of location of the terminal end, and~ for e~ample pinhole-sized discontinuitie~ in the internal layer or in the outer sur~ace lay~r. Thus, in many packa~ing applications; there are less Ytringent requirements with respect to barrier layer continuity, outer structural layer ~ncapsulation of the bar~ier layer, and uniformity and extension of the barrier layer into the flange~ In such applications, a container wherein the leading edge or fold line (e.g. 1121 in Fig. 9D) extends approximately to or just within the pinched wall thickness area ~ormed during the double seaming operations, will suffice. Suitable containers could contain minor imp*rfections such as pin holes and relatively insignificant discontinuities in the barrier material or in the encapsulating material, and non-uniform leading edge 33 of the internal layer. The terms substantially continuous, substantially encapsulated and substantially uniform are intended to encompass such accep~able containers.

It is to be understood that with respec~ to all inventions disclosed and claimed herein, tbe terms "marginal .

1l end portion of a side wall~ applies equally to the marginal edge or end portion of an article having no side wall, for example a phonograph record, a disc, or a blank.

Fig~ 3, an enlargect portion broken away from side wall 26 on the left of container 23 of Fig. 2A, clearly shows the relative positions and t:hicknesses of the respective five layers o~ the pre~erred multi-layer injection molded or injection blow molded container of this inven~ion.

Fig. 4, a vertical sectional view of an enlarged broken away portion of bottom wall ~7 and of side wall 25 of th~ container of Fig. 2A, shows that in a preferred injection molded or injection blow molded container for oxygen sensitive food products which must be heat sterilized in the container, the bottom wall total thickness is on the average less than the side wall total thickness. Also, generally speaking, the thickness of the internal or barrier layer is on the average greater in the bottom wall than in the side ~all. More particularlyi the ratio o~ the thickness o~ the internal layer or barrier layer 16 in the ~ottom wall relative to the total thickness of the bottom wall, is greater than the ratio of the thickness o~ the internal layer in the side wall relative to the total thi~kness of the side wall. Pre~erably~ the thickne~s o~ the internal layer in the bottom wall is at least the thickness of that layer in the side wall. Pig. 4 al50 shows that the total thickne s of a central portion of the container, gen~erally designated 40, which includes the sprue axea, is thicker than the total thickness of other areas of the rest of the bottom wall, and that at least in central portion 40, the thickness of the internal ].ayer is greater than the average thickness of the internal layer in the side wall. Central portion 40 includes downwardly depending trails or tails 42 of internal layer 16 and adhesive material 17, 18 encapsulated within outer structural layer ~, 15.

~ 'igs. 5 through 7 are enlarged cross-sections as might be taken through various locations of the marginal end portion of a preferred injec:tion molded or blow-molded five layer open ended piastic container such as the one shown in FigO 2. ~ore particluarly, Fig. 5 shows that the marginal end portion of the internal layer 16 extends into the container flange 29, and the terminal edge or terminal end 33 of the internal layer is encapsulated by intermediate layer material, which can be comprised o~ either or both of adhesive layers 17 and 18, also respectively designated ~he se~ond and first intermediate layers. As will be explained, preferably, terminal end 33 of internal layer 16 is encapsulated primarily or entirely by first intermediate layer material, adhesive layer E, 18.

Fig. 6 also shows another embodiment wherein ~he terminal end 33 of internal layer 16 is encapsulated within intermediate or adhesive layer material in a portion of the marginal and portion of a container side wall. Fig~ 6 shows a portion o the mar~inal end portion of the internal layer 16 or internal layers 16, 17, 18 fold@d over toward the outside of the container within the marginal end portion of the container side wall 26. The internal layer or layers are folded over along a fold line generally designated 44 near th~ terminal end 48 of the container flange 29. The folded over portion, designated 46 of the internal layer or layers, extends downwardly in outside layer ~, 15 of the side wall.
The terminal end portion of the internal layer is that portion of the marginal end portion which is near or adjacent the terminal end, usually, the terminal end portion is within the length o~ the folded over portion of the internal layer.

Fig. 7 shows another embodiment wherein the terminal end 33 o~ internal layer 16 is encapsulated within intermediate adhesive material. In Fig. 7, a portion o~ the marginal end portion of the internal layer 16 or layers 16, 17, 18 is folded over along a fold line 44 toward the inside of the container and ~he folded over portion and marginal end portion 46 is within flange 29~

~.~5~i%~

In the articles of this invention having a portion of the internal layer or layers folded over, the leading edge of the internal laye~ in the marginal end portion, usually the flange, o~ article, parison or container, can be the fold line 44 or the terminal end .33 and as meant herein, its meaning encompasses the furthest extent of the internal layer from the bottom wall whether it be the fold line, the terminal end or some other portion of the internal layer.
Preferably the leading edge or the plane along the leading edge of the internal layer is substantially unbiased relative to the axis of the containers on the terminal end 4~ of the container side wall. In the articles of this invention, the ; terminal end of the internal layer or layers is more removed from the terminal end of the container, for example, terminal end 48 of flange 29, than is another adjacent directionally-related marginal end portion of the internal layer or Layers. The terminal end of the folded over portion of the internal layer or layers is more removed than the fold line is from the terminal end of the container. Also, there is less variation in the distance from the ~old line to the terminal end of the container than from the terminal end of the internal layer to the terminal end of the container. The folded over portion may but need not lie near another portion of the internal layer as shown. It could extend in a direction away from another portion of the internal layer, for example such that the terminal end o~ the fol~ed over portion is further removed than any other folded over portion is from the folded over portion or the non-folded over portion of the internal layer. As contemplated herein, the _folded ovar portion need not extend in a relatively straight line as shown, but it may have, curled, compressed or other con~igurations. It is to be noted that in a single container, the marginal end portion of the internal layer or layers may have di~ferent configurations at different circumferential locations about the container flange. For example, in one radial segment of an arc about ~h circumference of the flange, the marginal end portion of the internal lalyer or layers may not be folded over, as in Fig.

?~

~25~ i7 5, in another segment it may be folded over slightly, in another segment, it may be more folded over to the outside of the container, as in Fig. 6, and, still in another segment, it may be folded over to the inside of the container slightly, greatly, or moderately as shown in ~ig. 7. Another possible configuration is one wherein the terminal end of the unfolded portion of the internal layer and the fold line are located in the terminal end portion of the container side w~ll. In Fig~ 7, the terminal end of the folded over portion may extend downwardly within inside layer 14~ Methods of forming articles having one or more folded over internal layers are disclosed later herein.

~ ig. 8, a schematic vertical section through a multi-layer plastic container or this invention whose internal layers are not shown, represents an estimate of the overall dimensions of a typical 202 by 307 inch container, based upon the di~ensions of the blow-mold ca~ity in which the container would b~ blown, considering some shrinkage of t~e container due to cooling upon removal from the blow~mold ca~ity. The dimensions represented by the letter designations are shown in the Table belowO

T~BLE

.
Letter Dimensio _ ~ h g) Designation Typical Range(+) a 2~28 .OlC
b 2.08 .010 c 3.40 ~010 d 2.95 .010 e 2.19 .010 f 1.90 .010 ~ .55 .010 h 3.08 .010 i .027 .003 .~

~l~S6~;'7 TABLE

DI~ENSIONS FOR FIGURE 8 (Continued) LetterDimension (inches) DesignationTypical Range(+) j .031 o010 k .020 .010 1 .37 .010 .:
Fig. 8A schematically shows the profile of ~he bottom of a plastic container of this invention whose internal layers are not shown. More partiGularly, Fig. 8A is a tracing of the bottom surface of an actual container, and i5 an approximation of the inside sur~ace based upon thickne~s measurements taken at various points along the bottom. Fig. 8A shows that the thickness of the central ~ortion of tpe bottom i~ greater than that of the rest of the bottom.
: `
Figs. 9 through 10A are enlarged vertical sections through various embodiments of clo ed multi layer pla~tic containers of this invention having internal layers folded - over in different configurations and at different locations within the marginal end portion of the container side wall.
~ ~ .
In Fig. 9 there is shown a container 50 wherein the ~ar~inal end portion o the internal layer 16 (hereinafter, for Figs. 9 th~ough 10A, referring to the layer individually or collectively with layers 17 and 18) is not folded over, and the marginal end of the container side wall 26 has a container end closure 52 double seamed thereto. The double seam includes a suitable adherent material 54 between the contain~r flange and the inside surface of the end closure portion which runs from its arcuate por~ion at the ~op of the containe!r side wall, through the portion which forms the double seam, to the terminal edge of the end closure.
-:

Fig. 9A shows another embodiment represented by another marginal end portion of either the container shown in Fig. 9 or another container having an end closure 52 double seamed thereto wherein a portion of the marginal end portion of internal layers 16 is fo]Lded over towards the outside of the container in container flange 29. The olded over configuration shown in Fig. 9A is preferred for a double seamed container ~or packaging oxygen sensiti~e foods.

Fig. 9B represents another embodiment of a container of this invention identical to those shown in Fig. 9 and 9A, except that the folded over portion of the marginal end portion of the internal layer 16 in ~ig. 9B is folded over ~oward the inside of the container.

In Fig. 9C, the folded over portion does not ex~nd a~ far into container side wall fl~nge 29 as it does in ~igs.
~A a~d 9B. Rather, it only e~tends to the arcuate portion of the top end of the container sida wall beyond the point wh~re adhesive 54 is positioned between the inside arcuat e curface o~ the end closure and th~ convex upper portion of the container side wall. The loc~tion of the folded over portion of the internal layer in Fig~ 9C does provide an acceptable barrier to unwanted substances. Por example, when the internal layer 16 is an oxygen barrier material, the location of the folded over portion provides an adequate barrier ~ince the travel path for oxygen i~ an extended one which requires the oxygen to travel up through the outer layer 15 over the folded over portion and back down through the inner layer 14 to reach t:he inside of the containes.

In Fig. 9D, the fold over portion located in the marginal ~!nd portion o~ the container side wall is folded over toward the outside of the container, and fold line 44 which in t:his case is the leading edge of the internal layer extends to about the bottom of the double seam. While perhaps not providing an adequate barrier for the long helf life for Zl highly oxygen sensitive food product this ' ~ 7 configuration and location of the folded over internal layer or layers would provide adequate barrier proper~ies for less sensitive food products and products which are not oxygen sensi-tive. Preferably at least part of the folded over portion of the internal layer is in the flange.

Figs. 10 and lOA show embc)diments of the multi-layer plastic containers of this invention having a flexible lid sealed to the container flange. In Fig. 10, the folded over portion extends upward into and toward the inside of the contai~er side wall. In Fign lOA, the folded over portion extend downward and into the outside portion of the container side wall. Whereas Figs. 9 through lOA shown substantially rigid and closures doubled seamed, and ~lexible lids otherwise sealed to embodiments of the containers of this invention, other suitable end closures, lids and securements are contemplated to be within the scope of this invention. The end closures 52 which have successfully been double seamed to the marginal end portions of the containers of this invention were metal end closures made of aluminum, organi- ;~
cally coated TFS steel and ETP steel and were double seamed to the container flanges by use of a conventional double seaming machine such as a Canco 400 , 006 , or 6R double seamer, modified with special seaming rolls. More particularly, the second operation rolls had different grooves, shorter axially and shallower diametrically then those commonly used for metal can bodies. Such rolls are currently used for double seaming metal end closures on plastic ham cans and on composite fiber cans.
Any suitable metaL end closure can be employed and the methods and means or securing or double seaming the ends to the cont~iners are within the knowledge of those skilled in the art.
Examples of suitable adherents 54 are sealing compounds sold under the trande designation SS A44 by Dewey & Almy, a Division of W. R. Grace & Company for packaging fruit and vegetable products, and made and sold under the trade designation M 261* by Whittaker Corp. for *Trademark .
: . ' ' packaging meat products. Flexible lids such as ~hown in Fig. 10 and lOA can comprise single or multl-layer plastic materials and can include one or more foil layers. The flexible lids 64 may be secured in any suitable manner to the container side wall, for example by heat sealing or by use of an adhesive. Suitable adhes~ves for flexible lids for paclcaging ho-t-filled food products include a ho$ melt materia:L chosen to provide a peel strength sufficiently low in magnitude to permit easy removal by peeling lid 64 from the container 26 and to maintain a hermetic seal to protect product integrity. Flexible lids having a suitable adherent thereon can be obtained under the trade desig-nation of SUN SEAL EFA~-123040 PET/ALU./PE/SEALA~T AH , and of SUN SEAL EFXW-123020 PET/ALU./PE/SEALANT/KW from SANEH Chemical of Japan.

It is to be understood that although the aforementioned discussion refers to five layer containers, the articles contemplated to be within the scope of the inventions need not have a side wall, and -they may be comprised of three layers, such as generally represented by Fig. 9D, or they may be comprised of more than three layers, for example seven or more layers.

An injection blow molding line which includes the apparatus of this invention, suitable for forming the articles, parisons and containers of this invention according to the methods of this invention, will now be described. Having reference to Figs. 11, 12, 13 and 14, the inje~tion line, generally designated 200, includes three hoppers, 202, 204 and 206 which receive granulated polymeric material therein and pass it to three respective underlying heated in~ection cylinders 208, 210 and 212. Each cylinder contains a reciprocating in~ection screw rotatably driven by respective motors 214, 216, 218 to melt the granulated polymeric material. Each in~ection cylinder is located to the rear of rear injection manifold 219, a rectangular solid block formed of steel. Manifold 219 has polymer flow *Trademark -: : .
: ' .- ~ - ' .

5~

channels drilled in it and each injection cylinder has a nozzle which injects polyme~ric material into the opening o~
an associated flow channel in the manifold's rear face. The channels in the manifold divida in two, the ~low straams from two cylinders, 208 and 212, so that ~ive polymer ~low streams are created and exit from the forwasd portion of manifold 219.

The rear injection manifold 219 is bolted by bolts 259 to ram block 228, a rectangular solid block of steel having polymer flow channels drilled therein. The five flow streams of polymeric materials pass out of manifold 219 and into the channels within the ram block 228. The channels within the ram block lead to the respective sources of polymeric material displacement which preferably are five rams, 232, 234, 252; 260 and 262, which are bolted to the top of the ram block (see Fig. 14)o In accoroance with a displacement-time schedule, described later, each ram is moved to ~orce the material of each of five polymer flow ~treams through downs ream channels drilled in the ram block 228, through channel~ drilled in a forward r~m manifold 244 which i~ a rectangular steel block bolted by bolts 263 to the front of the ram block, through channels drilled in ~ani~old extension 266 which is a cylindrical steel block bolted to the front face of the ram manifold, and through channels drilled in a runner extension 276 which is a cylindrical steel block whose front face 952 is bolted by bolt 174 to the runner block 2a8 (qee Fig. 31). The runner extension pas-es through a hore 280 in a first fixed support means or fixed platen 2~2 and extends into a bore 286 drilled in runner block 288 in which the front end of the runner extension is supported. ~he polymer flow out of the channels of the runner ~xtension and into channels drilled in the runner block. The channels in the runner block lead to two ~-splitters 290 (see Fig. 28) inserted in the runner block, t~en through channels ln the runner block to ~our Y-splitters 292 (see FigO 28) inserted in the runner block, and then through channels in the runner block to eight feed blocks 294 ~5~

(see Eigs. 32 and 41) inserted in the runner block, and, finally from the feed blocks to eight injection nozzle assemblies (also called nozz:Les or injection nozzles), generally designated 296, each noz~le assembly being mounted in the forward end of a feed block.

Eight nozzles are mounted in runner block 288 in a rectangular pattern of two columns of four nozzles each tsee Figs. ~9A, 29B). Each nozzle 295 injects a multi-layer shot of polymeric materials into a juxtaposed injection cavity 102 mounted on in~ection cavity carrier bloGk 104 in turn mounted on a fixed injection cavity bolster plate g50 ~Fig. 98), to form a multi-layer parison.

A side-to-side moveable core carrier plate 112 mounted on an axially moveable platen 114 carried by tie barQ
116 carries sixteen cores 118 in two eigbt-core sets and is moveable to align one set of eight cores and seat t~em ~i~hin eight injection cavities 102. A cylinder (not shown) drives the carrier plate transaxially from side to side to position the cores respectively with the injection cavities 102 and blow-mold cavities 108. Suitable driving mear.s know~ to the art, such as generally designated 119 and including drive cylinder 120, a housing, oil reservoir, hydraulic pump, filtering system and related electrical cabine~s, moves the moveable platen along the tie bars to seat the set of eight cores in the injection cavities. This system designated 119 also drivec~ all of the extruders 210, 212 and 214, and it drives core carrier plate 112. Concurrently with the iniection forming of the eight parisons, eight parisons previously injected onto the other set of eight cores are positioned in associated blow-mold cavities 110, mounted in blow-mold c:arrier blocks 108, in turn mounted in blow-mold bolster plalte 106 (see Fig. 13), for inflation into the desired container shape. When the injection cycle is completed (eight parisons are ~ormed), the platen is moved rearwardly and the core carrier plate is reciprocated to the opposite side of the machine where, when the platen is moved ~ 25~

forwardly, the eight cores ~arrying parisons are seated within an associated set of blow-mold cavities 110 in which the parisons are inflated.

Purther details of the apparatus will now be described having particular reference to the portions thereof through which pass the melt streams of material for each o~
the layers comprising the injected articles. In the preferred embodiment, there are three sources of supply of polymer material, namely, hopper 202 of extruder unit "IH for supplying the polymer material which will form the inside and outside structural layers A and B, hopper 204 on extruder un~t "II", for supplying the polymer material C which will form the internal layer C, and hopper 206 of extruder unit ~III" for supplying adhesive polymer for forming adhesive layers D and E. It will be understood that in the illustr~ted embodiment the same polymeric material is used to form layers A and B and the same polymeric material is used t~ form layers D and E. Wh~n layers A and B are formed o~
di~ferent materials, separate extruder units Ia and Ib (not shown) are used. When layers D and E are formed of different materials, separate extruder units IIIa and IIIb (not shown) are used.

Considering extruder unit I, the polymer melt rlow stream is forced out of cylinder 208 by its reciprocating extruder screw which moves the polymer material through nozzle 215, sprue bushing ~21 and into channel 217 drilled in rear injection manifold 219. The flow of the structural polymer melt material is divided in manifold 219 into two e~ual-distance channels 220, 222 drilled in the manifold and whose paths proceed in opposite horizontal direc~ions.
Channel 220, which is split to the right (upwards in Fig. 14), carries the polymer melt stream material which will form the A inside structural layer of the article to be formed. Channel 222, which carries the polymer melt stream which will form the a structural outside layer of the article, is split to the left and turns roughly 90 and 8~
~Q .

~L~5~ i;7 passes axially and horizontally out of a hole in the forward face 224 of the ~ear mani~old 219 and into an aligned channel drilled in the ram block 228. In ram block 228, each respective channel 220 and 222 communicates with a check valve 230 and then with the inlet to a sour~e of polymer material displacement and pressurization, which~ in the preferred embodiment, are rams 232, 234, each ram having connected thereto a servo controlled drive means or mechanism, here shown as including a servo manifold 236 and a servo valve 238. One of the servo controlled drive means, generally designated 180~ for ram 252, and representative of the servo drive means for each of the rams employed in this invention, is shown in Figs. 18, 18A and 18B. The servo system controls the di~placement versus time movement of the rams.

With specific reference to Fig. 14, the operations of the five rams/ 23~, 232, 252, 260 and 262, are controlled by the selective application of drive signals to the five respective servo valves 2~8, 254 and 264 couplPd to each o~
these rams. Figs. 18, and 18A and 18B, show the conventional ram construction~ employed and show, for ram 252, a hydraulically driven ram piston 253 and servo control means compri3ed of controllable servo valve 254 which provides hydraulic oil into double ended hydraulic cylinder 181 for driving the ram piston 253 into and out of position. Each of the rams is driven in accordance with a desired time sequenca for providing appropriately dimensioned pressures for i~suring the manufacture of the article with the proper configurations. As will be set orth in urther de~ail below, major functions of the injection control are accomplished by virtue of a system processor which controls the overall movement of the various major segments of ~he apparatus for performlng the injection sequence. Thus, a predetermined operational sequence iq programmed into the system processor for moving the moveable core carrier pla~e along the tie bars for positioning the sixteen cores in their respective eight core sets. The processor drive acts to ~3 5i7 drive the moveable platen by energization of the hydraulic cylinder, generally represented as 119, as by opening a valve and permitting hydraulic oil to flow therein, so that the parisons previously described may be placed in the appropriate positions both for injection onto one set of eight cores and for blow-molding for inflation into the desired container shape from the other set of eight cores.
The operations, including clamping, movement of the moveable platen, and other major injection cycling sequences are thareby controlled by the system processor in accordance with movements governed by means of various limit switches strategically placed at locations defining the limits of movements of these various'apparatus segments within the general machine configuration. A second processor, suitably programmed, takes over the specific operation of carrying out th~ injection cycle when the moveable platen is properly positioned for an injec~ion cycle on the injection cavities.
Tbis second proceqsor directly controls the various rams by controlling the hydr,aulic fluid flow into the ram cylinders for purposes of applying pressure along the respec~ive feed channel operatively connected to the ram. Since ram position is critical in determining ram pressure, appropriate feedback ~echanisms are provided from each ram servo mechanism for ~e~dback to the second processor and utilization in the program for purposes of accurately determining ram position.
As shown in Fig. 18B, two transducers are employed, the first transducer 184 determining the position of the cylinder, and thereby the appropriate pressure, and the second transducer 185 determining the velocity of movement o~ the cylinder within the servo. Si~nals along appropriate lines 184A and 185A, are electrically conducted ~rom the position transducers to the second processor for control purposes, Each of the servos shown in Fig. 14 is provided with corresponding transducers for accurately determining their respective positions. The relationship of ram position to pressure is shown in greater detail and described further below.

. ~ _ ~i6~:~7 ~ rom the rams, each channel 220, 222 proceeds axially and horizonta~ly through bores drilled in ~am block 228 and, by means of respective holes in forward face 240 of the ram block and matched aligned holes in rear face 242 of forward ram manifold 244, channels 220 and 222 pa~ out of ram block 228 and into channels drilled in forward ram manifold 244. In forward ram manifold 244, each channel 220 and 222, for flow of the respective inclde structural material A and outside structural material B, turn approximately 90 and run ~enerally perpendicular to the axis of the machine to a point where the channels again turn 90 and again travel in the axial direction to holes in forward ram manifold forward face 246.

In similar fa~hion, the polym~r material which is to form the internal layer C is forced out of injection ~ylinder 210 of extruder unit II by an e~truder screw which moves the ~aterial for~ard from th~ extruder through a no~zle 248, prue bushing 249, and into central flow channel 250, which enters the rear face of rear injection manifold 219,. turn~
90 and travels left (downward in Fig. 14~ in a ho~izon~al path above channel 220 until it rea~hes tha axial center line of the rear injection manifold where channel 250 turns 90 and travels axially out of a hole in forward face 224 of the rear manifold 219 into a matched, aligned hole in the rear face 226 of ram block 228. In ram block 228, channel 250 communicates with a check valve 230 and then with the inlet to a source o~ polymer material displacement and pressurization, which, in the preferred embodiment, is ram 252 having servo 254 and manifold 256 connected theretoO
~rom ram 252, channel 250 proceeds axially and horizontally to a hole in the forward face 240 of ram block 228. Channel 250 enters.a hole in the rear face 242 of forward ram manifold 244 and passes through manifold 244 in an axial path to a hole in the forward face 246.

Extruder III forces the polymer material which is to form the internal D and E layers of the article through injection cylinder 212, through nozzle 213, sprue bushing 223 and into channel 261, which enters the rear face of rear injection manifold 219~ In the rear manifold, channel 261 turns approximately 90 and travel~ on a plane below channel 217 in a horizontal path to~ward, and until the channel meets, the a~ial center line of th~e rear manifold 219. Channel 261 then ~urns approximately 90 and proceeds a short distance in the axial directionO It th~en splits into two oppositely directed horizontal channels 257, to the left, and 258, to the right (up in Fig. 14), which travel perpendicularly to th~ axis toward the opposing sides of the rear manifold, where they each again turn about 90 and travel axially~ out of holes in the forward face 224 of the réar manifold. Flow channels 257 and 258 for the polymer of layers E and D are located in the rear injection manifold 219 below the flo~
channels for the polymer of layers B and A. Those holes communicate with matched aligned holes in the rear fa~e 226 of ram block 228 which form continuations of channels 257,

2~8 in the ram block. Each of those channels co~municates with ~ check valve 230 and then with the inlet to sources of polymer ~aterial di~placement and pressurization, which, in the preferred embodiment, ~re rams 260, 262 each of ~hich has a servo valve 264 and servo manifold 265 connected thereto.
From rams 260, 262, the channel~ proceed forward in an axial, horizontal direction and communicate with matched, aligned holes in the ram block forward face 240 and in ~he forward manifold rear face 242. Channels 257, 258 continue axially, horizontally forward a short distance into forward manifold 244 where each again turns 90 and returns toward the axis until they reach respective points near but spac~d from the axis where each turns 90 and travels again in the axial direction to where they communicate with holes in forward face 246 of the forward ram manifold 244. The rear and forward ram manifolds 21~ and 244 are each attached to opposite :~aces of the ram block by respec~ive bolts 259, and 263.

To prevent clogging of the melt flow channels, ~2~

particularly those where tbe dimensional clearances are small, e.g. in the nozzle assemblies 296, ~ppropriate filters may be placed in the flow channel of each melt material, preferably between the extruders and the rams. It is desirable that each flow stream prior to reaching the no~zles pass through a restricted area at least as restricted as the most restricted polymer flow stream path in the nozzles, to there remove any undesired matter from the polymer stream.

Channels 220, 222, 250, 257 and 258 then travel through bores drilled in manifold extension 266 connected to the forward face 246 of the forward ram manifold 244. ~n the forward face 268 of the manifold extension 266 are a plurality of nozzles 270, one for each channel which passes through the manifold extension. ~ach nozzle is seated in a pocket 272 at the rear face 274 of runn*r extension 276. The runner extension 276 is mounted at its rearward end portion 278 tbrouyh a bore 280 in fixed platen 282, and at its orward end portion 284 through a-bore 286 in runner blo~k 288. As chan~els 220, 222, 250, 257 and 258 pass through manifold extension 266, they are rearranged (when viewed in vertical cross-section~ from a qpread out pentagonal or star pattern at its rearward portion to a more tightened pattern at its forward ~nd portion, such as the quincu~cial pattern ~hown. As the channels pass through runner extension 276, they are rearranged/ when viewed in vertical cross section, from the pattern of the quincunx, at the rear end portion 278 of the runner extension, to a substantially flattened horizontal pattern near the forward end portion 284 of the runner extension~ At the forward end portion 284, each channel i~ split into sub-channels, as will be more ~ully explained in conjunction with Fig. 29~ and directed through channels in a runner or runner block 288 to two T-splittess 290, and then through channels in runner block 288 to ~our Y-splitters 292 and ~hen through channels in runner block 288 to eight feed blocks 294 (two shown), each one of which is mated with a nozzle assembly, generally designated 296c Each feed block contains five passageways or feed channels, each ~1 of which carries a stream of polymer melt mate~ial which is to form a layer of the inject:ed article.

Referring to Fig. 15, entrances designated 219 I, II
and III to channels 217, 250 and 261 are cut into and through rear manifold 219 at different respective elevations and travel along horizontal paths. More particularly, entrance 219 II receives the polymer melt material that is to form internal layer C of the multi-layer plastic article to be formed. It communicates at the upper right corner of manifold 219 with central flow channel 250 which travels axially in the maniold, and then the channel turns approximately 90 and is directed toward the axis (from right to left in Fig. 15). Likewise, entrance 219 I near the center of the rear face of manifold 219 receives the polymer mate~ial which forms the respective inside and outside 5tructural layers ~ and 3 of the multi-layer article to be formed. Entrance 219 I communicates with channel 217 which tra~els a short di tance ~xially forward into the manifold and is th~n split into two channels 220, 222 (dashed line in Fig. lS) which travel in right and left opposite horizontal directions each ~or a short equal distance to points wherein each channel turns substantially 90 and travals axially horizontally for short equal distances to holes where they exit the rear manifold's forward face 224. At the lower left corner o rear manifold 219, the polymer melt material which is to form internal layers D and E of the multi-layer article passes through entrance 219 III which communicates with channel 261 which passes a short axial distance horizontally into manifold 219, then makes a substantially 90 right turn and travels along a substantially horizontal path below and parallel to channels 220 and 250. At the axial center line of manifolcl 219, channel 261 turns at a substantially 90 angle and travels a short distance orward and into the manifold, where it then splits into two opposi~ely directed channels 257, 258 of equal length which run left and right perpendicularly outwardly away from the axial cen~er line to where the respective channels again turn subqtan ially 90 ,~

and travel axially forward into and through the short length of the ram mani~old and exit through holes in the forward face 224 of rear manifold 219. The rear manifold has three metal plugs 225 each seated and located ln a respective bore in the manifold by a locat~r pin 231 and each being pressure locked therein by a threaded set screw 229. The manifold has holes 302 therein for receiving bolts 259 (not shown) for bolting the rear ram manifold to the ram block and it has a threaded drill hole plug 303 for sealing channel 261. The rear manifold also contains oil flow channels 309 which run from side end to side end horizontally through the manifold for circulation of heated oil which maintain the manifold and the polymer melt streams running therethrough at the desired temperature.

Rear injection manifold 219 contains a metal plug 225, retained by set screw 229, having two portions of channel 227 drilled therein at right angles and with a ball end mill at the int2rsecting end o~ each portion. (See Eigs.
lS and 16). The ball end mills establish a 5pherlcal surface at the intersection of the channels which provides a smooth transition right angle turn to the polymer flow channel 222.
Such a smooth transition turn prevents unde irable stagnation o~ polymer melt flow which otherwise tends to occur at sharp turns of a polymer melt stream flow channel. All turns of flow channels in the rear injection manifold 219, ram block 228, forward ram mani~old 244, manifold extension 266, runner block 288, ~-splitters 290 and Y-splitters 292, where drilled channels intersect to form the turn, are smooth transition turn to prevent polymer stagnation. The turns are formed by ball end mills or other suitable means either in the channels drilled in the injection manifold, ram block, etc., or, when the geometry requires it, in channels drilled in plugs 225 or plugs ~imilar thereto.

Referring to Fig. 17, hopper 204 is supported on injectioll cylinder 210 of extruder unit II which plasticize~
the polymer melt material which is to form lnternal layer C~

~25~

Injection nozzle 248 at the forward end of the injection unit II is seated in and communicates with ~prue bushing 249 having a nozzle seat 251 which in turn communicates with channel 250, for carrying polymer C, bored or cut horizontally through rear manifold 2190 A ball check valve 230 communicating with channel 250 allows material to pass through the check valve in the foward direction but prevents the material fro~ flowing back into rear manifold 219 from pressure exerted by in~ection ram 252 having a hollow chamber, and a vertically reciprocable piston 253 and an accumulator seated therein. Channal 250 in ram block 228 communicates with ram bore 255. Shown in phantom attached to the top of ram 252 is a conventional servo control mechanism g2nerally designated 180 (more particularly described in relation to Figs. 18 and 18A). Channel 250 for the C
material is cut s$raight hori~ontally and axially through ram block 228 and communicate~ with a matched hcle in forward face 240 of the ram block and in rear face 242 of the forward ram manifold (see Fig. 14), which in turn ~ommunicates ~ith the continuation of channel 250 th~ough ~orward ram manifold 244. Channels 250, 220, a~d 257 ate directed horizont~lly forward through ram block 228 in separate, parallel paths at di ferent elevations. As will be explained, the entire ram block, generally designated 245~ which includes rear injection manifold 219, ram block 2~8, orward ram manifola 244, and manifold extension 266, is heated by suitable means~
here shown as a plurality oE bored and communicating oil ~low channels running horlzontally through the widths of its components for circulating a heated oil or another suitable heated ~luid. The oil flow channels are designated 309 for the rear ram manifold, 310 for the ram block ~nd 311 for the forward ram manifold. Forward ram manifold 244 has vent holes 313 therein for venting polymer material which has leaked from an interface of the manifold extension with an adjacent structure, and to prevent the material from blowing the plugs 225 out of the structure. ManiEold extension 266 is bolted ~o the forward face 246 o~ forward r~m manifold 2~4 by bolts 267. As will be explained, the manifold ex~ension ~0 tightens the pattern of respective channels 250, 220 and 257 as well as those of the other channels not here shown, such that the channels are in a tight quin~uncial pattern when viewed in vertical cross-sect:ion, for communication with runner extension 276. The respective flow channels continue from the manifold extension t:o runner extension 276 by means of nozzles 270 which are seat:ed in pockets 272 in runner extension rear ~ace 274.

Pressure transducer port 297 is located in the upper portion of manifold ext~nsion 266. It is at this location, approximately thirty-nine inches away from the tips of nozzle~ 296, that the pressure measurements of Table I~ were madeO

The support a~d dri~e mechan~sm for tbe entire ram block 245 will now be described. (See lower portion of Fig.
17.~ Cross fr~mes 328 and longitudinal frames 330 tone shown) support a pair of wear strips 332 and a pair of mounting ~leds 333, which in turn support a long ram block stand-of~ 334, and a sled drive bracket 336 which in turn supports short ra~ block stand-off 338. A
horiz~ntally-mounted ram block sled drive cylinder 341 is connected to mounting slsds 333 and drive bracket 336, and which latter structures are bolted together, thereby drives entire ram block 245 rearward and forward to thereby ~ring the nozzle~ 270 on the mani~old extension into and out of seated engagement with the pockets 272 in the rear face 274 of the runner extension 276. Main extruder carriage cylinder 34Q i~ bolt.ed at its forward end to fixed platen 282 and, through its cylinder rod 343 and rod extension 345, it is connected t:o and drives main extruder carriage 347 to which is attached main extruder unit I. As will be explained in conjunctiom with ~igs. 98, 105 and 106, once nozzles 270 are seated, the ram block sled drive cylinder 341 maintains sufficient force, in conjunction with clamp cylinders 986 and drive cylinder 340, to maintain a ~eated leak proof engagement between the nozzles and the runner extension.

~

:~259~

Referring to Figs. 18 and 18A, one of the conventional servo control mechanisms 180 employed in this invention and which drives and controls ram 252 is comprised of a servo manifold 256, a servo valve 254, a double~ended hydraulic cylinder 181 having an upper rod 18~ and a threaded lower rod e~tension 133 to wbich is connected ram piston 253, and velocity and positlon transducers, generally designated 184, 185, which as will be explained, co~nunicate with and provide signals to microprocessor 2020 (Fig. 141). A
separate servo control mechanism similar to the one generally designated 180 is connected to and drives each ram 250, 234, 252, 232 and 262.

Referring to Fig. 19, a view of the rear of rear manifold ~xtension 219 shows that the paths o~ channels 220, 2~2, 250~ 257 and 258 which enter the rear of the manifold extension at ho}es 318, 316, 314, 320, 322 are arranged in a spread or enlarged, five-pointed star pattern. In manifold axtension 26S, the paths of channels 2~0, 222, 250, 257 and 258 are changed from their horizontal paths in for~ard ram manifold 24~ to inwardly an~lsd paths which tighten the quincuncial pattern such that the channels exit through holes 318', 316', 314', 320', and 322' which are arranged in a tighter four-pointed quincuncial pattern, relative to the central exit hole 314', ~or caxrying the internal layer C
material (see Fig. l9A, a view of the front facs of the manifold extension). ~ozzles 270 are seated in bores 323 in the frsnt face 268 of manifold extension 266. The nozzles are connected to and communicate with respective manifold extension exit holes 314'-, 316', 318', 320' and 322'.
Nozzles 270 protrude into and are seated in matching pockets 272 cut into the rear face of runner extension 276 where the sprue or mouth of each noz21e co~municates with a matched, aligned entrance hole in the runner exSension psckets, which holes i~ turn co~municate with aligned continuations of the five polymer flow channels 220, 222~ 250, 257 and 258 bored into the runner extension.

_ ~ O

~2~6;~

As is more fully descri~ed below, an importan~
feature of the present inveltion is that it facilitates production of substantially uniform, multi-layer injected articles from each of a plurality of injection nozzles. This is achieved, in past, by having the flow and flow path and flow experience of each melt material from the material moving means, material displacement means, or source of material displacement, -- the ram --, to the central channel of any one o~ the plurality of injection nozzles 296 (Fig.
14), be substantially the same as that of each of the corresponding melt materials in the othPr corresponding flow channels, as the material travels from that ram to the central channel of any of the other no~zles. The arrangement of the flow channels~ branch points and exit ports in the polymer stream flow channel splitter devices of this invention, includin~ runner extension 276, T-splitters 290 and Y-splitters 292, and other parts of the apparatus (see, e.~., Figs. 28 and 29C), is designed to assist in providing such a flow ystem., The flow pattern of the five flow channels 220, 222 250, 257 and 258 is rearranged in the runner means of this invention which is a polymer flow stream splitting and distribution 5y5tem, here including runner extension 276 ~rom a tight-knit star pattern at the rearward end portion 278 of the runn~r extension to an axially-spaced, radially or horizontally offset pattern along the horizontal diameter in the forward end portion 284 of the runner extension (see Fig 203. Thus, channel 250 for the polymer C material travels directly thrnugh the center line o~ the runner extension along its axis. Channels 220 and 222 ~or the respective structural layers A and ~ are drilled within the runner extension at an angle downward and outward relative to its axis (se~ Figs. 20, 21 and 30). Channels 257 and 25~ for the material i-or layers ~ and D, respectively, are drilled at an angle upwardly and slightly inwardly relatiYe to the axis of the runner exten ion ~see Figs. 20 and 21).

`- ~

The flow channel for each melt material is split or divided at a branch point, generally designated 342, in the forward end portion 284 of the runner extension. The locations of the branch points 342 are such that the flow and flow path of the melt material passing through any given branch point is, from there to any one of the injection nozzle assemblies, the same as from there to every other nozzle assembly. In tne preferred embodiment, the branch points 342A, 342B, 342C, 342D and 342~ for the respective ~aterials forming layers A, B, C, D and E of the multi-layer injected articla, preferably located in a common plane (a horizontal plane in this embodiment) but in different vertical planes, are spaced from each other horizontally and along the axis of the runner extension and are radially offset with respect to the axis of the runner extension, in the sense that other than branch point 342C, each is on a radius of a different length measured from the axis.

In the preferred embodiment o~ the injection nozzle assembly 296, described ~elow, the melt stream for each of the layers of the injected article enters the central channel 546 of the nozz}e at locations spaced from each other along the axis of channel 546 (see Pig. SO). The melt stream from which is formed the outside structural layer ~ of the injected article enters the nozzle central channel 546 at an axial location closest to the gate at the front face 596 of the nozzle. The ~elt stream from which is for~ed the inside structura~ layer A o~ the injected article enters the nozzle cantral cbannel 546 at an axial location farther from the gate of the nozzle than any of the melt streams which form the other layers of the injected article. The melt stream (or streams) which form the internal layer (or layers) of the injected article enter the nozzle central channel at an axial location (or set of axial locations) between the melt streams ~or layers B and A. In the preferred ~ive-layer injected article, the locations at which the five melt streams for those layers enter the nozzle central channel 546 are in the order B, E, C, D, A. Preferably all orifices other than for ~L~5~
!

the inside structural layer, here A, are axially as clo~e as possible to the gate of the injec~ion nozzle. The axial order of sequence, from front to rear, of the five branch points 342 in the runner extension is~ 342B, ~42E, 342C, 342D
and 342A, respectively, for the materials from which are formed layers B, E, C, D and A of the injected article. At each branch point, the axial end portion of the primary flow channel is split into two branches, referred to as first and second branched flow channels which are bores equal in length and respectively directed at an angle u~ward and downward toward, and communicate with and terminate at, a plurality of first exit ports 344 and a plurality of second exit ports 346 (see Figs. 20-28). Each plurality of exit ports is axially aligned and spaced in the same order along the respective top and bottom peripheral surface portions of forward end portion 284 o~ runner extension 276 for presentation to and communication with flow channels in runner block 288.

The amount of radial offset of branch point 34.2B
~rom the axis of the runner extension is the same as for branch point 342A, and the radial o~fset-for branch point 342E is the same as for branch point 342D. It is desired that the radial offsets for the branch points of the layer A
and B materials, be similar to facilitate achievement of equal response time in each layer in each pair. The same applies to the respective flow channels in the entire ram block 245. It also applies to the layer D and E materials where it is desired to start flow of both substantially simultaneously into the nozzle central channel. It should be noted that, because o nozzle geometry, in which the orifice for the layer E material is located closer to the open end of the nozzle central channel than the ori.fice for the layer D
material, as described later it i~ desirable to have a small time lag i:n the introduction of layer E material into the nozzle central channel to compensate for the axial difference in nozzle ]position of the ori~ices for the materials of layers E and Do ~5~ 5~
I

!

The construction of the preferred runner extension 276 and pattern of travel in it of each of the material flow channels can be more clearly understood by reference to Figs.
20-28. Channels 220, 222, 257 and 258 are bores of circular cross-section drilled from the rearward end or rear face 274 generally axially, at a compound angle in and through a portion of the length of the cylindrical block of steel out of which the ~unner extension is made. ChanneI 250, also referred to as the central flow channel, is a circular bore drilled along the central axis of the runner extension. As the plurality of channels pass axially forward through the runner extension, they are gradually oriented or rearranged from a radial, tight star or quincuncial pattern, (Fig. 22) at ~he rear Eace 274 and rearward end 278, of the runner extension, where each channel passes through a common vertical plane, into a more flattened, substantially horizontaL, axially spaced or offset pattern (Fig. 23) at the middle porton 279 of the runner extension. In the forward end portion 284 of the runner extension, the axial end portions 715, 716, 717, 718 and 720 of the flow channels are split or divided at spaced, horizontally coplanar branch points 342A, 342B, 342C, 342D and 342E, each in a different plane vertical to the axis of the runner extension, into two branches, referred to as first and second branched flow channels.

The branch point 342C for material C is formed at the intersection of axial end portion 717 of central flow channel 250, and is the bore portion drilled on the axis of the runner extension, at the intersection with a bore through the runner extension along a diameter thereof (see Fig. 26) and which forms first branched flow channel 704 and second branched flow channel 705. The other branch points are each formed at t:he intersection of two equal angular bores which form the branches or first and second branched flow channels, e.g. 700 and 701 for the first and second branched flow channels of channel 222 for material B (see Fig. 24), drilled into the runner extension from opposite diametral locations, 9~o g~

;'7 to intersect with the generally-axial compound-angle bore for channel 222. Smooth transition turns are formed at each branch point by using a ba:Ll end mill to finish the bores.

In the embodiment just described, the axial end portions 715, 716, 717, 718 and 720 of flow channels 220, 222, 257 and 258 (for respe~ctive layers A, B, E and D) adjacent to and ypstream of respective branch points 342A, 342B, 342E and 342D intersect the branch points at compound angles. As a result, the angle of intersection between the upstream portion of the channel, for example axial end portion 715 of channel 222 (Fig. 20), and one of the adjacent branches of the channel downstream of the branch point, for example the bore which forms branch 700 of channel 222 (~ig.
24), is substantially the same as but not identical to the angle of inter~ection between the upstream connecting channel portion and the other adjacent downstream branch, for example the bore which forms branch 701 of channel 222. This may c use a slight bias of flow at the branch point, generally ~avorin~ iow into the downstream brancA having the larger angle of intersection with the up tream connective channel portion. In the above described embodiment, however, the angles of intersection are substantially the same, the maximum difference being three degrees off the perpendicular and satis~actory, multi-layer injected articles from a plurality of injection nozzles have been made, and the above-stated object of having substantially eyual ~low and flow path to each injection nozzle is achieved.

Where the manuacture of injected articles requires it, the previously-described ~light flow bias may be substantially eliminated by having the angle of intersection be the same, as in the alternative embodiment of the runner extension described below.

In the first alternative embodiment o~ the runner extension (see Figs. 28A-28~), the angle of intersection between the axial end portions of flow channels 220, 222, and '~ I

258 and the adjacent downstream two branches of the flow cbannel is the same. In this particular alternative embodiment, the axis of the axial end portion o~ each flow channel is either on or genlerally on the central axis o~ the runner extension. Thus, thle axial end portion 717 o~ central flow channel 250 for the C layer material is on the central axis of the runner extension. Channel 222 for the B layer material has a connecting channel portion 710, adjacent to and upstream of branch point 342B', which is perpendicular to the central axi~ o~ the runner extension; channel 257 for the E layer material has a connecting channel portion 711, adjacent to and upstream of branch point 342E', which is perpendicular to the central axis; channel 258 for the D
layer material has a connecting channel portion 712, adjacent t~ and upstream of branch point 342D', which is perpendicular to the central axis; and channel 220 ~or the A layer m~terial has a connecting channel portion 714, adjacent to an ~lpStream of branch point 342A', which is generally axlal to the central axis. (See ~igs. 28G and 2~) Each of the upstream connecting channel portion~ 710, 711, 712, and 714 is long ~nough for the melt material flowing therethrough and entering the branch point to have largely forgotten the direction in which it was moving in the compound-angle channels prior to flowing into the connecting channel portion. Each of ~he branches or branched ~low channels 700' and 701', 702' and 703', and 704' and 705' of flow channel 222, 257, and 250 which is adjacent to and downstream of respective branch points 342B', 342E', ana 342C', is perpendicular to the respective upstream connecting channel portions 710, 711, and to axial end portion 717, and thus, for each of these ~low channels, th angle of intersection between the adjacent upstream portion and each adjacent downstream branch is the same. Each of the adjacent branches or branch~ed flow channels 706', 707' of flow channel 258 which is downstream of branch point 342D' intersects the upstream connecting channel portion 712 of channel 258 at the same angle; and, similarly, the intersection angles are the same betwlen upstream connecting channel portion 714 in plug q8 725 ~see Fig. 2BG) of channel 220 and the branches or branched flow channels 708', 709' of cha~nel 220 which are adjacent and downstream of branch point 342A'.

~ his alternative embodiment of the runner extension shown in Figs. 28A-28~ is made by first drilling the bore for the axial channel 250 and the bores for generally-axial channels 220, 222, 257 and 258. Four parallel diametrical bores 722, 7~3, 724 (fully threaded), and 725 (see Fig. 28G) ~or forming connectin~ channels 710, 711 and 712, are drilled to inter~ect the bores for channels 222, 257, 258 and 220. A
cylindrical metal insert or plug, generally designated 72fi, retained by a set screw 727, is inserted into diametrical b~res 722, 723 and 725. Only a set screw 727 is employed in bore 724. Perpendicular boras are drilled on a diameter through the runner extension and the internal ends of the plugs to form the perpendicular branches or branched flow channels 700', 701' and 702', 703' of channels 222 and 257 which are adjacent to and downstream of branch points 342E' and 342~'. The plugs 727 may be temporarily removed, extract any -~evered ends o the plugs an~ any feathered edges. Equal angular bores are drilled through the runner extension and respectively into the plugs in bores 724 and 725, to form the branches or branched flow channels 706', 707' and 708', 709' of.respective channels 258 and 220 which are adjacent to and downstream of branch points 342D' and 342A'. A ball end mill is used to form the branches 708' and 709' from connecting channel 714 in plug 727'. Though not shown in Fig. 28F, Fi~s. 28G and 28~ show that generally axial flow channel 220 has an axial end portion 720 which communicates with straight, connecting channel portion 714 in plug 725 which, in contrast with the other connecting channel portions of this embodiment, runs axial to the runner extension.

A second alternative embodiment of the polymer flow stream channel splitter device of this invention is runner extension 276" (see FigsO 28~ and 28I). In this embodiment, there is a plurality of spaced substantially vertically ~L~5~ i7 arranged polymer stream flow channels 2~2, 257, 250, 258 and 220r bored substantially axially through the runner extension 276n. The flow channels each have an axial porSion which terminates in an axial end portion 715, 716, 717, 718 and 720, each of which in turn communicates at rounded connecting points with connecting channel portions 710n, 711n, 7137, 712~ and 714 n . The connecting channel portions extend from the connecting points vertically within the runner extension 276 n in an axially-spaced pattern and are connected at their downstream ends to, and then communicate with respective branch points 342B~, 342E", 342C~, 342D" and 342A~. Each of the branch points is located in the forward end portion 284 of the runner extension in an axially spaced, hor~zontally substantially coplanar pattern wherein each branch point is in a different vertical plane. At each branch point, the channel is split into branches, here designated first ~nd second branched flow channels, 700n and 701a, 702" and 703", 704" and 705n, 706~ and 707n, and 708~ and 709n, each o~
which is e~ual in length and communicates with and terminates at respective first and second exit ports 344, 346, in different qur~ace portions of the periphery of he forward end portion of the runner extension. The first and second exit ports for a flow channel are in the same vertical and horizontal plane, each of the first and second exit ports for each flow channel are in different vertical planes relative to the exit ports of each other flow channels, and the plurality of ~irst exit ports 344 of the first branched flow channels and the plurality o~ second exit ports 346 ~or t-be ~econd branched flow channels is each arranged in its own respectiYe axially-aligned spaced pattern of exi~ ports along a common line in different periphe-al surface portions of the runner extension, for presentation to and communication with corresponding flow channel entrance holes or channels in runner bLock 288 of the multi-coinjection ~ozzle, multi-polymer injection molding machine of this invention.
The vertical bores which form the respeçtive connecting channel portions 714" and 710n, are commenced through the top periphery of the runner extension, said holes being sealed by ~L~S~257 cylindrical metal plugs 726 which are retained by set screws 727.

The respective polymer flow streams which form the respective layers of the article to be formed in accordance with this invention, in this embodiment, and which exit the peariphery o the runner extlension 276" through respective first and second exit ports 344 and 346, follow respective paths similar to each other in and through runners 350B' and 351B' in runner block 288' to two respective T-splitters 290', then through runners 352', 354' and 355' to four more respective T-splitters 290' and then through respective runners 356', 357', 35B', 359', 360', 361', 362' and 363' to a respective feed block 294 each of which is associated with a respective one of the eight nozzles assemblies 296.

It i~ preferred that the materials flowing out of ~ach exit po~t 344 be isolated from the other exit ports 344 and likewise with respect to exit ports 346. In the pxeferred embodiment and the first alternatiY~ embodiment of the run~er exten~ions, the isolation means for isolating the polym~ flow streams preferably include stepped cut expandable piston rings 348 (two of the six employed are shown) which seat in respectiYe annular grooves 349 ~ormed in forward end por ion 284 of the runner extension 276 (see Fig.
21). The isolation means are sufficiently compressible to pe~mit insertion and withdrawal of runner extension 276 into and f~om bore 286 in runner block 288 (see Fig 14 and 30), while sti:Ll maintaining sealing engagement with the bore and the runner extension when the runner extension is in operating position within the runner block. Isolation means such as expandable mating cast iron strips are to b~ employed with runner extension 276~. The middle portion 279 of the runner exl:ension 275 contains a plurality of annular fins 2~1 which cooperate with the internal surface of a main bore 975 in oil rel:ainer sleeve 972 (see Fig. 30) and with the intersticeas between the ins to provide channels 277, 277A
for the f}ow of heating oil about the runner ext2nsion.

~\

~iL2~

Preferably, ealin~ means are employed downstream of the foremost of the exit ports 344, 346, i.e., those most proximate to runner extension front face 952, and upstream of the rearmost exit ports, i.e., those most remote from front face 952, to substantially prevent polymer material which exits the ports, from flowing axially downstream of the foremost sealing means and upstream o~ the rearmost sealing means in the runner block bore 286 in which the runner extension sits. Preferably, the sealing means includes stepped cut piston rings 348 seated in annular grooves 349.
All of the piston rings bear against and cooperate with the inner surace of bore 286 to provide the effective isolating and sealing functions~

The paths of respective polymer flow strea~s A-E
which form the respective layers of the article to be formed in accordance with this i~vention and the channels or ~unners through which they flow from the periphery of the run~sr extension 27S throuyh respective top, first, and bottom second exit ports 344~ 346 through the runner block 288, through runners 350, 351 to two T-splitter 290 then through runners 352~355 ts four Y-splitters 292 and then through runners 356-363 to the respective feed block 2g4 for each of the eig~t no~zle assemblies 296, will now be described in ,re~erence to Figs. 28, 28I, 29, and 29C through 31. Fig. 28, a vertical cross- ection taken along line 28-28 of Fig. 21, shows the path o~ the A polymer material from the runner e~tension through the runner block, and ~ig. 28I shows the same for the 8 material from the second runner extension embodiment 276~. Figs. 29 and 29C through 31 show various views of the runner block and its components 276, 290~ 292, 294 and 296 in that portion o~ the injection molding machine of this inve~tion which is located forward or downstream of manifold extension 266. Fig. 29 sho~s the front of the injection portion of the machine, absent injection cavities 102 and injection cavity carrier blocks 104 (see Figs. 13 and 98), and through injection cavity bolster plate 950. ~he view ~hows ~he overall polymer stream flow path and channel ~256~

pattern (dashed lines) for the B material through runner block 288 (dashed lines). Fiy. 29 also shows the pattern of eight nozzle assemblies 296 arranged in two vertical columns of four assemblies in each column, and ~ive stepped bores, generally designated 152, which enter the sides of runner block 28~ at an angle and form the respec~ive runners, four of which are plugged at their entrances by plugs, generally designated 154 (see Fig~ 45A), each having a threaded head 155 and a nose 156. The tip of the nose 156 of each plug extends into the runner block to a point near the periphery of a feed block 294 (located behind a nozzle assembly 296)o The nose of the fifth plug 154', one for each feed block, is elonyated, fits closely into anti-rotational hole 158 in the feed block (see Figs. 29C, 41, 45, 45A and 45B) and not only plugs the fifth bore but prevents the feed block from rotating in the runner block.

Fig. 29C, a vertical section taken along line 29C 29C of Fig. 98, shows the polymer stream flow paths in runner block 288 for the B polymer material. The vertical section is taken through C-stando~f 122, through the runner block and through feed blocks 294. Fig. 29C also shows those plugs 154 in stepped bores 152 which have an elongated nose lS6 whose tip is engaged in anti-rotational holes 158 in the feed blocks and thereby prevent the feed blocks from rotating in the runner bores in which they sit.

As shown in Figs. 28, 28I, 29, and 29C throu~h 31, and considering the preferred embodiment of the runner extension 276, and the runner block 288, each of the first exit ports 344 along the top periphery and each of the second exit ports 346 along the bottom periphery of the preferred runner extension 276, raspectively communicates with runners 350, 351 which are holes or channels drilled or bored vertically through the runner block 288. Each of the polymer flow streams exit through the respective upper and lower exit ports 344, i46 directly into and throuyh respective runners 350, 351 and then the flow streams (350B, 350E, 350C, 350D

\~

25;~

and 350A, and 351B, 315E, 351C, 351D, and 351A) (see Fig. 32) travel into an associated T-splitter 290 which plits each respective flow stream into two opposite but equal streams (352B-352A, 353B-353A, upper left and right (in Fig. 28) 354B-354A, 355B-355A, lower left and right), each of which flows through runners 352, 353, 354 and 355 which in turn lead into a Y-splitter 292. Each Y-splitter 292 takes each incoming flow stream and in turn splits it into two diagonally divergent, but equal~ flow streams 356B-356A and 357B-357A (upper left in Fig. 28), 358B-358A and 359~-35gA
(upper right), 360B-360A and 361B-361A (lower left), 362B-362A and 363B-363A (lower ri~ht), each of which flows ~hrough runners 356, 357, 358, 359, 360, 361, 362, 363 in runner blo~k 288 to a ~eed block 294 for a noz~le assembly 296. The feed block functions to receive each of the flow streams B, E, C, D, A and separately direct the appropriate one into the appropriate shell of the nozzle assembly, generally designated 296, and whose rear portion is seated within the forward end of the feed block.

The flow path for each of the polymeric materials B, E, C, D and A, ~hich comprise the injected articles and injection blow molded articles of, and produced by, the present invention has been quickly traced from the source of its flow to an injection nozzle. It is an important feature .
of the present invention that the flow and flow path for each material, for a particular layer is substantially identical, for that material and layer, deæirably from the source of flow of the material, extruder Units I, II and III, and preferably from the place where a flow channel is spli~, e.gO, at a branch point in the runner extension, to and through the runner extension and to each of the nozzle assemblies. Thus, for example, the flow of material C splits at branch point 342C in runner exten~ion 276 into two equal, symmetrically-directed and s~mmetrically-volumed flow paths 350C and 351C. The rate of flow of material C is the same in path 350C as in 351C. The flow of material C in path 351C i then again equally and sy~metrically divide~ in T-splitter ~5~ 7 290 into equal flow paths 354C and 355C, and patb 35gC i5 yet again equally and symmetrically divided in Y-splitter 292 into equal flo~ paths 360C and 361C, each of vhich enters a different feed block 294 and associated nozzle assembly 296.
It is to be further noted that the materials A-E are maintained separate and iso:Lated from each other, throughout the apparatus, from the first location where the A, B, D and E materials are split in ram manifold 219, up ~o the location where the material enters th central channel of the injection nozzle assembly 296. The purpose and function of this separate, equal and symmetrical flow path system is to ensure that each particular material ~e.g., polymer C for layer C) that reaches the central channel of any one of the eight nozzles has experienced substantially the same length of flow path, substantially the same changes in direction of flow path, substantially the same rate of flow and change in r~te of ~low, and substantially the same pressure and change of pressure, as is experienced by each corresponding material for the same layer ~e.g, polymer C for layer C) which reaches any one o~ the remaining seven nozzles. This simplifies and facilitates precise control over the flow of each of a plurality of materials to a plurality of co-injection nozzles in a multi-cavity or multi-coinjection nozzle injection molding apparatus, and provides substantially the same characteristics in the corresponding materials and layers in and of each layer of each of the eight multi-layer articles of and formed in accordance with this invention.

Fig. 30 is a vertical section taken along line 30-30 o~ Fig. 29. At the upper part o~ Fig. 30, the vertical section through the runner extension 276 shows channels 220 and 258 ~i.n dashed lines) for the A and D material flow streams and (in solid lines) channel 250 for material C.
Fig. 30 shows channel 250 passing through the axial center of the runner extension to branch point 242C where it communicates with straight up and down branched first and second flow channels 250. Fig. 30 also shows runner channels 351 in rurner block 288 for flow streams 351B-351A, each of 1~S
- 1~3 -which channel at second exit port 346 respecti~ely communicates directly with entrance ports 364 in ~-splitter 290.

The vertical section shown in Fig. 30 does not show Y-splitter 292 but merely shows runners 361 broken away within the runner block and communicating with entrance ports 392 and 396 in the peripheral wall of the feed block 294.
The polymer flow streams flow through the feed block into the noz31e assembly 296, at the bottom left in Figs. 29, 29C and 32. It is to be noted that all inlets, and radial and axial feed channel portions are shown schematically, out of position.

The injection cavity structure is shown schematically in Figs. 30 and 31. The profile is not accurate nd details of the cavity, such as fins, etc., are no~ -qhown.

Eig. 31, a top view of a horizontal section taken along line 31-31 of Fig. 29, is a horizontal section taken diametrically through runner extension 276~ ~ig. 31 shows channel 250 (in solid lines) or internal layer C material and channels 258 and 257 (in dashed lines) respectively for ca~rying the polymer flow streams of the material which will form the D and E layers of the article to be formed in ac~ordance with this invsntion. At the forward end portion 283 o~ runner extension 276, the axially-aligned spaced dashed lines indicate the bottom holes 346 for each of the polymer flow streams B, E, C, D and A, at the bottom of ~he runner extension. FigO 31 shows runner portions 360 broken away but communicating with entrance holes in the periphery of the feed block 294 (located at the second from the bottom left in Figs. 29 and 29C) which has mounted within the re~eiving chamber in its orward end portion section, a nozzle assembly 296.

~ ig. 31 also shows a ~et of grease channels, generally designated 168, sealed at their entrance and exit ports by plugs, and extending through pin cam base 892 and pin cam base cover 894, for providing grease for lubrication of the drive means of this invention, more particularly, pin sleeve cam bars 850, for their reciprocation through pin cam bar slots 890. Likewise, grease channels 170, sealed at their entrance and exit ports by plugs and extending through sleeve cam base 900, provide ~or grease lubrication of sleeYe cam bar 856 in sleeve cam bar slot 898, and sleeve 860 in bore 902 of the pin cam base. Fig. 31 does not show stepped bores 152 or plugs 154 therein.

Fig. 32 shows the three preferred elongated cylindrical polymer stream channel sp}itter devices of the invention, runner extension 276, 276' and 276", T-splitter 290 and Y-splitter 292, for the multi-coinjection nozzle, multi-polymer injection molding machine sf this invention~
The devices are shown in axially parallel positions as they are mounted in the center and lower le~t portion of runner block 288 ~not shown~. Each device has a polymer stream entrance surface portion having a plurality of spaced, aligned flow channel entrance ports bored therein and communicating with a plurality of respective polymer flow channels bsred into the device wherein each flow channel is split into branches or first and second branched flow channals which in a device are substantially equal in length and which communicate with and terminate at respective first and second exit ports, each positioned in a different polymer stream exit surface portions of the. device, for presentation to and communication with corresponding flow channel entrances or holes in runner block 288.

The T-Splitter The structure of T-splitter 290 will now be described (FigsO 33-36). Fig. 33, a top plan view of the T-splitter shown in Fig. 32, and Figs. 34-36 show that each T-splitter is a cylindrical steel block into whose top ~5;$~5~

surface are dsilled five axially-aligned entrance bores or ports 364 which communicate with and form entrance flow channels 367 each of which enters the device radially and transaxially to a branch point where the entrance channel intersects with and splits into two symmetrical bores forming first and second exit or b~anched flow channels 368, 368'.
The axis or the entrance channel 367 intersects the axis of the branched flow channels 368 at a location above the central axis of the T-splitter. Each first branched flow channel communicates with and terminates at a first exit port 366, and each second branched flow channel communicates with and terminates at second exit port 366', the plurality of each of which set of exit ports is axially-aligned along a line and is respectively located about 90 around the circumference of the T-splitter from entrance port 364. In the T-splitter shown, the communicating entrance port, entering flow channel, branch point, first and sacond branched flow channels and first and second exit ports for a polymer material, are pre~erably all in a common vertical plane. The entrance channels at each end of the T-splitter are of the same diameter and are larger in diameter than the mid~le ~hree entrance cha~nels, which themselves are of the same size. The diameter of each branched flow channel 368, 368' is the same a-~ the entrance channel which it intersects. Preferably, the axis of each branched flow channel, say 368, is drilled transaxially at an angle of about 15 to the horizontal canter line, to meet the entrance channel and the opposing exit flow channel 368', at a point below the axial center line. Six annular grooves 370 are cut into the cylindrical surface of the T-splitter to serve as seats for stepped cut piston rings 369.

Rotation of the T-splitter within the bore in which it is ~eat:ed in the runner block is prevented by locking pin means located at one end of the T-splitter. The locking pin means comprises two cylindrical cone-pointed locking pins 144 carried within diametrical bore 146 in the shoulder at the end of the T-splitter. The outer end of each locking pin has .' ~0~
_ ~ _ 6~7 a spherical or rounded surface and the inner end of each locking pin has a 45 conical surface. ~otation of cone point set screw 140 carried in axial tapped hole 143 at the end of the T-splitter causes the set screw to act as a wedge to drive the locking pins radially outwardly to press the spherically-surfaced end of each pin against the bore in the runner into which the T-~plitter is inserted. The T-splitter is held in it~ axial position in the runner bore in which it is seated by threaded lock nuts 291 each of which is screwed into a threaded end portion of the bore, the T-splitter being wedged axially therebetween tsee Fig. 30).

The Y-Splitter The structure of the Y-splitter 292 will now be d~scribed (Figs. 37-40). Fig. 37, is a side elevational view of the Y-splitter shown in Fig. 32, as would be seen along line 37-37 o~ Fig. 38, shows that each Y-splitter is a cylindrical steel block into whose peripheral sur~ace are d~illed five axially-aligned entrance b~res or ports 371 ~hich communicate with and form entrance flow channels 373 each of which enters the device radially and transaxially to a branched point where the entrance channel intersects with and forms two symmetrical bores forming first and second exlt or branched flow channels 374, 374'. The axis of the entrance channel 373 intersects the axis of the first and second branched flow channels 374, 374' at the center line of the Y-splitter. Fig. 38, a side elevational view of the Y-splitter of Figo 37 rotated 4S clockwise, shows that each first branched flow channel co~municates with and terminates at a first branched exit port 372 and each second branched flow channel with a second branched exit port 372', the plurality oE each set o~ exit ports af which is respectively axially-aligned along a line respectively located about 130 around the circumference of the Y-splitter from entrance port 371. The entrance channels at each end of the Y-splitter are of the sa:me diameter (about one-hal~ inch) and are larger in diameter than the three middle entrance channels, which ~ 2~;6~

themselves are of the same size (about three-eighths inch).
The branched flow channels are all of the same diameter (about one-quarter inch) and are smaller than the entrance channels. Preferably, the axis of each of the first and second branched flow channels 374, 374' is at an angle of about 39a from the horizontal line and its junction is at the axial center line of the device. Six annular grooves 376 are cut into the cylindrical surface of the Y-splitter to serve as seats for stepped cut piston rings 375.

The materials flowing into and out of the T-splitters and Y-splitters are kept separate and isolated from each other by isolating means which, in the preferred embodiment, are expansion type stepped piston rings 369 (two of the six are shown) which seat in annular grooves 370 foEmed in the periphery of T-splitters 290, and step cut pi~ton rings 375 (two of the six are shown) which seat in annular grooves 376 formed in the periphery of Y-splitter~
292~ The isolation means are suf~iciently compressible to permit insertion and withdrawal of the T-splitters and Y-splitters into and from the bores in runner block 288 in which they are located, yet they are capable of S~
maintaining sealing engagement with the bores and the splitters when the splitters are in operating position within the runner block.

~ referably, sealing means, preferably also in the form expandable stepped piston rings 369 and annular grooves 370 in which the rings sit, with respect to the ~-splitters, and, piston rings 375 and annular grooves 376 with respect to the Y-splitters, are respectively employed downstream of the foremo~t and upstream of the rearmost entrance ports 364, and of the foremos~ and rearmost first and second branched exit flow channels 368, 368' for the T-splitters, and downstream of the foremost and upstream of the rearmost o~ the entrançe ports 371, and o~ the foremost and rearmost first and second branched e;xit flow channels 374, 374' for the Y-splitters, to substantially prevent polymer material which enters and exits i7 the respective ports, from flowing axially downstream of the foremost sealing means and upstream of the rearmost sealing means in the runner extension bores in which the respective splitters sit.

As shown in Fig. 38, Y-splitter 292 i~ held in rotational position in the runner bore in which it is seated in the same manner as T-splitter 290 is held in its runner bore, a cone-pointed set screw 140 in axial hole 148 wedging or forcing a pair of cone-pointed pins 144 apart in diametric~l bore 150 against the surface of the runner bore for the Y-splitter.

The Feed Block The structure of the feed block 294 will now be de~cribed (Figs. 41-48). Tbe feed block is a cylindrical block of steel having at one end a threaded extension 37 having a bore 379 therein, extending axially from the rear face of the feed block~ Sealing ring retaining cap 821 threads onto ex~ension 378 and retains sealing rings 8lg in bore 379. Cut into the opposite, forward or front face of the feed block i~ an axially extending co-iniection noxzle or noz~le assembly receiving stepped chamber 380 having a~
axially innermost first shelf 3~2 and first annular wall 383, a second shelf 384 and second annular wall 385, and an axialiy outermost third shelf 386 and a third annular wall 387 which communicates with front face 388 of the feed block. The shelves are the transaxial portions and the annular walls ~re the axial portions of the steps. The feed block has a central channel 390 which communicates with bore 379 and, when the stepped rear portion of nozzle assembly 296 is inserted into chamber 380, is aligned with the central channel of the nozzle. In a preferred embodiment, the valve means for controlling the flow of materials A-E in the nozzle comprises ~in and sleeve means which fit within and pass through re1:aining cap 821, bore 379, sealing rings 819 and central channel 390 of feed block 294, and extend forward and fit within the central channel of the noz21e assembly 296.

Each of the eight feed blocks 294 separately receives each separate polymer flow stream of the five passed to it through the appropriate five runners designated either 356, 357, 358, 359, 360, 362 or 363 ex~ending from the Y-splitters. Thus, each feled block receives the five separate polymer flow streams (i.e., streams 361~, 361E, 361C, 361D and 361A, as shown in Fig. 32). While maintaining them separate, the feed block changes their overall direction of 410w by about 90~, preferably in the manner described below, from radial entry to axial exit, and passes each of them separately and axially into an associated plurality of nozzle shells which together with a nozzle cap comprise the co-injection nozzle or co-injection nozzle assembly of this invention, generally designated 296.

Basically, each polymer flow stream is radially received in an inlet which co~municates with a peripheral feed throat through which the stream flows along or about a portion of the periphery of the feed block. ~ost of the feed throats have a terminal end portion where the strea~ passes into a feed channel having a radial portion which runs radially into the feed block towa~d its central axis and turns and extends axially to an exit hole in ~he stepped receiving chamber through which the stream is passed axially to the appropriate nozzle channel.

Polymer flow stream inlets 392, 393, 394, 395 and 396 are rounded grooves cut radially inwardly into the outer periphery of the cylindrical feed block 294. Each of inlets 392-395 has a defining wall formed by a .156 inch radius extending from the inlet's center point. The center points for each of the inlets fall on a common cen~er line which runs axially along the top of the feed block (see Fig. 32).
~he defining wall of each inlet is the origination of grooves or feed throats 398, 399, 400, 401 and 402 cut into and along the outer surface of the feed block.

`~

The structure of feed block 294 through which passes the polymer A flow stream will now be described. Inlet 392 is the origination of a feed thro~t 398 (dashed lines in ~ig.
41) cut approximately .196 inches deep by a 5/16 inch spherical ball end mill into a portion of the periphery of the feed block. Throat 398, when viewed in verticle section has a bottom wall and flat opposed side walls with rounded surfaces therebetween. Throat 398 runs a 60 circumferential arc counter-clockwise about the periphery of the feed block.
(Fig. 45) At the end of the 60 arc, ~eed throat 398 communicates with a feed channel 404 cut radially and angularly in the forward direction (left in Fig. 41) into the feed block towards central channel 390. Prior to reaching the central channel, feed channel 404 turns axially into an axially-cut forwardly extended key slot 406 which communicates directly with the cent~al channel along a portion of the length of its wall 391 lFig. 43) and which terminates in a matching key slot exit hole 407 in the first shelf 382 in nozzle assembly receiving chamber 380 at the forward end portion of the feed block.

~ The structuze of feed block 294 through which pa~ses the polymer D flow stream will now be described. Inlet 393 or~ginates feed throat 399 cut into a portion of the outer periphery of the feed block in the same manner as that of feed throat 398. Throat 399 runs a clockwise circumferential arc of 120 about the periphery of the feed block (Fig. 46).
At the end of the 120 arc, feed throat 399 communicates ~ith a feed channel 408 cut radially directly into and straight to~ard the central axis of the feed block to a controlled depth which in this preferred embodiment is .298 inch from the centr21 axis~ There the feed channel communicates in a 90 turn with obloround feed channel 410 which is approximately .093 inch by .251 inch. Channel 410 passes axially through the feed block and terminates in a matching obloround exit hole 411 in the first shelf 382 in nozzle assembly receiving chamber 380 at the forward end portion of the feed block.

_ ~ _ 'i~f'~ 57 The structure of feed block 294 th~ough which passes the polymer C flow ~tream will now be described. Inlet 394 is the origination of feed throat 400 cut into a portion of the periphery of the feed block in the same manner as that of feed throat 398. Throat 400 runs a counter-clockwise circumferential arc of 120 about the periphery of the feed block (Fig. 47). At the end of the 120 arc, feed throat 400 communicates with a feed channel 412 cut radially directly ~owards the central axis of the feed block to a controlled depth which in this preferred embodiment is .516 inch from the central axis of the feed block. There the feed channel communicates in a 909 turn with obloround feed channel 414 which is approximately .125 inch by .251 inch. Channel 414 passes axially at that depth through the feed block and ~erminates in a matching obloround exit hole 415 in the second shelf 384 in nozzle assembly receiving chamber 380~

The structure of feed block 294 through which passes ~he polymer E flow stream will now be described. Inlet 395 is the origination of feed throat 401 cut into a portion o the periphery of the feed block in the same manner as that of throat 398. Throat 401 runs a clockwise circumferential arc of 180 about the periphery of the ~eed block (Fig. 48). At the end of the 180 arc, feed throat 401 communicates with a feed channel 403 cut radially toward the central axis of the feed block to a controlled depth which in this preferred embodiment is G.734 inch from the central axi~ o~ the feed block. There the feed channel communicates in a 90 turn with obloround feed cbannel 41S (dashed lines in Fig. 41) in which is approximately .125 inch by .251 inch. The center line of channel 416 is .734 inch from the central axis of the feed block. Channel 416 passes axially through the feed block and terminates in a matching obloround exit hole 417 in the third shelf 386 in nozzle assembly receiving chamber at the forward end portion of the feed block (Fig. 41).

The polymer B flow stream enters the feed block through inlet 396 which is the origination of feed throat 402 ~.25;~57 cut radially and into a porti.on of the outer periphery of the feed block. ~hroat 402 runs forwardly axially along the outer periphery of the feed block and cooperates with the surface of bore 822 in runner block 288 (Fig. 50), into which feed block 294 is seated, to form a passageway or channel 460 for the low of polymer B to the forward end of the feed block, where the polymer exits at port 418 formed by channel 460 and bore 822. Throat 402 is .093 inch deep and .250 inch wide.

Fig. 42, an end view cf the feed block of Fig. 41, shows the shelves, the exit holes previously described and their radially spaced arrangement. Fig. 42 also shows locator pin holes 420, bored into front face 388 of the feed block, and holes 421, 422 and 423 respectively bored in the third, second and first shelves of nozzle assembly receivi~g chamber 380. The holes receive locator pins tnot shown) which extend into associated locator holes in the shell~
comprising the nozæle assembly, to maintain the positions of and facilitate proper alignment of feed block ~xit holes 407, 411, 415, 417 and 418 with associated inlets in the nozzle assembly.

With reference to the claims to the feed block, inlets 392-395 are referred to as the first inlets, inlet 396 is re~erred to as the second inlet, the feed throats 398-401 are referred to as the first feed throats and 402 as the second feed throat, and the exit holes 407, 415, 417, 421 are referred to as the first exit holes, and 418 as the second exit hole.

The 8, E, C, D and A materials flowing into feed block 294 are kept ~eparate and isolated from each other by isolating means, which preferably include sealing means, here, expandable stepped piston rings 424 (two are shown in Fig. 41) and annular grooves 425 in which the piston rings se2t. Simi.lar piston rings are employed in the annular seats cut into the periphery of the T-splitter, Y-splitter and \1~
- ~3 - .

~5~

runner extension. The clearance between the internal diameter of the bore in runner block 28B, into which the feed block is inserted, and the feed block outer diameter is approximately .001 to .002~ inch. The expandable piston rings compensate for this gap and expand out to prevent intermixing of the materials flowing into the feed block.
The isolating means are particularly important in the preferred practice of the method of the present invention wherein the materials are under high pressure. Without this or equivalent isolating means, there could occur inter-material mixing and contamination in the ~eed block, which might result in an intermixed ~low of materials in the nozzle assembly, and lead to deleterious discontinuities of the layers of the multi-layer injected article. Preferably, sealing means such as just described, are also respectively employed upstream of the rearmost inlet 392 to substantially prevent polymer material directed at the feed block from ~lowing axially upstream of the sealing means in the runner block bore in whic~ the feed block sits.

Referring to Fig. 42, and using as a re~erence a radial line from the central axis of the feed block through the enter of exit port 418 and feed throat 402 for material B, the axis o key slot exit hole 407 and key slot 406 for material A is located 60 counter-clockwise from the reference, the center of exit hole 415 and channel 414 for material C is located 120~ from the reference, the center of exit hole 41~ and channel 416 for material E is located 180 from the reference and the center of exit hole 411 and channel 410 for material D is located 240 counter-clockwise ~rom the reference. The exit holes for the polymer flow stream are! provided in a radially-spread relatively balanced pattern to attempt to balance the heat distribution in the structure and prevent hot streaks therein, to provide relatively balanced overall pressure at the end of each nozzle assembly 2g6 (Figs. 49A, 49Aa, 50~ and prevent the assembLy from skewing as would be the case if say all the exit ports were in the top half of the end view. Any ;i6;~5~

relatively balanced pattern which meets the above objectives ls acceptable.

The Nozzle Assembl~

Referring to Figs. 49-77A and with particular reference to Fig. 50, the preferred embodiment of the nozzle assembly or co-injection nozzle or nozzle 296 of this invention comprises four interfitting nozzle shells 430, 432, 434 and 436, and nozzle cap 438 in which the nozzle shells fit. In actual assembly, the interfitted no~zle shells are arranged so that their feed channels 440, 442, 444, 446, 448 and feed channel entrance ports 450, 452, 454, 456, 458 are angularly offset as shown in Figs. 49A and 49AA. Using as a reference a radial line from the central axis of the interfitted shells through the center of entrance port 458 a~d feed channel 44B for material B in nozzle shsll 436, the axis of entrance port 456 and feed channel 446 in nozzle shell 434 is located 180 from the reference, the axis of entranGe port 454 and feed channel 444 in nozzle shell 432 is located 120 ~xom the reference, the axis of entrance port 452 and feed channel 442 in nozzle shell 430 is lscated 24Q
from the reference, and the axis of entrance port 450 and ~eed channel 440 in shell 430 is 60 from the reference. So arranged, the nozzle feed channel entrance ports are aligned with associated exit holes 407, 411, 415, 417, 418 in ~eed block 294. ~owever, in order more clearly to show the structure of the shells and their inter-relationship to each other, Figs. 49 and 50 depict the shells arranged with the centers of their feed channels located in a common plane.

As mentioned, the preferred nozzle is comprised of an assembly 296 of four interfitting nozzle shells enclosed within a nozzle cap. The outermost or first nozzle shell 436 contains a feed channel 448 for polymer B which communiGates with an annular polymer flow passageway 460 formed between a portion of the inner surface of the nozzle cap and a portion of the outer surface of the nozzle insert shell. ~he - l~5l-~2~6~7 passageway terminates at an annular exit orifice 462. The shell 436 is formed with first and second eccentric chokes 464, 466 extending into the ,passageway 460 and which rastrict and direct the flow of polym~er (Fig~. 50, 65, 67, 68 and 70). The flow restriction a:round the circumference of the first eccentric choke is greatest in the area 467 where the feed channel communicates with the polymer flow passageway~
The eccentric chokes function to assist in evenly balancing and distributing the flow of polymer around the circumference of the polymer flow passageway and its exit orificeO The eccentric chokes for all nozzle shells are designed to achieve steady state flow. A primary melt pool 468 (Fig. 50~
ij formed in flow passageway 460 between the rear wall 469 o the first eccentric choke and a forwardly tapered or pitched wall 470. Wall 470 defines the rear o~ the primary m lt pool 468 and is shaped approximately to conform to the streamlines that the polymer would follow in dividing from a solid stream, from the forward end of feed channel 4~8, to the cylinder that exits ~rom o~ifice 462. The pattern or shape of ~all 470 is intended to approximate the boundary between flow of polymer and no-flow of polymer which would otherwise become a pool of stagnant polymer. A secondary melt pool 47~
is ~ormed in flow passageway 460 between the forward wall 473 of the first eccentric choke and the rear wall 474 of second eccentric choke 466 (Fig. 50). A final melt pool 476 is formed in flow passageway 460 between the ~orward wall 477 of the second eccentric choke and the orifice 462 of flow pa-~sageway 460. The final melt pool 476 comprises a conical portion 478 which forms a tapered, symmetrical reservoir of polymer. The purpose o the tapered conical section is to increase the circumferential uniformity of the flow of polymer exiting from orifice 462. ~his is discussed below in re~erence to Fig. 77B, which shows a similar tapered conical f low chann~el.

I:nserted within the firs~ nozzle shell 436 is a second nozzle insert shell 434 having a feed channel 446 for polymer E (Figs. 50, 58-64~ which is angularly offset from -~Ig Sf~57 the feed channel 448 of polymer B by 180. The feed channel 446 for polymer E communicates with an annular polymer flow passageway 480 formed between a portion of the inner surface of the outer nozzle insert shell 436 and a portion of the outer surface of the second nozzle insert shell 434 (Fig.
50). The passageway terminates at an annular exit orifice 482. The second nozzle insert shell 434 is formed with first and second eccentric chokes 484, 486 (Fig. 63) extending into the passageway 480 and which restrict and direct the flow of polymer E for the purpose previously described. The flow restriction around the circumference of the first eccentric choke is greatest in the area 487 where the feed channel 446 communicates with the polymer flow pas ageway 480 (Fig. 50).
A primary melt pool 488 (Fig. S0) is formed in flow passageway 480 between the rear wall 489 of the first eccentric choke 484 and a forwardly pitched wall 490 (~igs.
58 and 63) which has the shape and function previously des~ribed with respect to wall 470. A secondary melt pool 492 is formed in flow passageway 480 between the forward wall 493 of the first eccentric choke 484 and the rear wall 494 of second eccentric choke 486 (Fig. S0). A final melt pool 496 is ~ormed in flaw passageway 480 between the forward wall 4~7 of the second eccentric choke 486 and the orifice 482 of flow passageway 480. The final ~elt pool comprises a conical portion 498 which forms a tapered, symmetrical reservoir of polymer for the purpose and func~ion previously described.

Within the ~econd nozzle insert shell 434 is a third nozzle insert shell 432 (Figs. 50, 55-57A) having a feed channel 444 for polymer C which is angularly offset by 120 (counter-clockwise when viewed from the shell's formed end or tip) from the feed channel 448 for polymer B. The feed channel 444 for polymer C communicates with an annular polymer flow passageway 500 formed between a portion of the inner surface of the second nozzle insert shell 434 and a portion of the outer surface of the third nozzle insert shell 432 (Fig. 501. The passageway terminates at an annular exit orifice 502. The third nozzle insert shell 432 (Figs. 55 and ~\c~
~ ~7 ~

~ ~5~

57A) is ~ormed with one eccentric ch~ke 504 and one concentric choke 506 which r.estrict and direct the flow of polymer C for the purpose pr.eviously described~ The flow restriction around the circumference of the eccentric choke is greatest in the area 507 where the ~eed channel 444 communicates with the polyme!r flow passageway 500. A primary melt pool 508 is formed in f.low passageway 500 between the rear wall 509 of the eccentric choke 504 and a forwardly pitched wall 510 which has the shape and functio~ previously described. A secondary melt pool 512.is formed in flow passa~eway 500 between the forward wall 513 of the eccentric choke 504 and the rear wall 514 of concentric choke 506. A
final melt pool 516 is formed in flow passageway 500 between the forward wall 517 of the concentric choke 506 and the orifice 502 of flow passageway 500. The final melt pool comprises a conical portion 518 which forms a tapered, symmetrical reservoir of polymer or the purpose and function p~eviously described.

Fitted within the third nozzle insert shell 432 is the inner nozzle insert shell 430 (Figs. 51 54A) ha~ing a feed channel 442 for pol~mer D which is angularly offset by 243 (counter-clockwise when viewed from the shell's forward end or tip3 from the feed channel 448 for polymer B in the outar nozzle insert shell. A portion of the inner surface of the third nozzle insert shell 432 and a portion of the outer surface of the inner nozzle insert shell 430 form an annular polymer flow passageway 520 for polymer D (Fig. 50). The passageway 520 communicates with the feed channel 442 and terminates at an annular exit orifice 522. The inner nozzle insert shell 430 is formed with one eccentric choke 524 ~Figs. 50, 51 and 53A) and one concentric choke 526 which restrict and ~irect the flow of polymer D for the purpose previou ly described. The flow restriction around the circumference of the eccentric choke is greatest in the area 527 where the feed channel 442 communicates with the polymer ~low passageway 520. A primary melt pool 528 is formed in flow passageway 520 between the rear wall 529 of the - ~r.~8 ;

~Z56?.,57 eccentric choke 524 and a forwardly pitched wall 530 which has the shape and function previously described (Fig. 51). A
secondary melt pool 532 i~ formed in ~low passageway 520 between the forward wall 533 of the eccentric choke 524 and the rear wall 534 of second concentric choke S26. A final melt pool 536 is formed in flow passageway 520 between the forward wall 537 of the concentric choke 526 and the orifice 522 of flow passageway 520. The final melt pool 536 comprises a conical portion 538 which forms a tapered, symmetrical reservoir of polymer or the purpose previously described.

Inner shell 430 contains a central channel 540 (Fig.
SQ) which is preferably cylindrical and through which passes, and in which is carried, the preferred nozzle valve control means which comprises hollow sleeve 800 and solid pin 834.
Con~rolled, reciprocal movement of sleeve 800 selectively bloc~ and unblocks one or more exit orifices 462, 482, 502 and 522, selectively preventing and permitting the ~low of on~ or more oE polymer5 B, E, C and D from those respective orifices. Inner feed channel 440 elsewhere sometimes referred to as a third orifice, for polymer A in inner shell 430 is angularly off.et by 60 (counter-clockwise when viewed from the sbell's forward end or tip) ~rom the feed channel 448 for polymer B in the outer shell 436. Feed channel 440 communicates with central channel 540, but flow of polymer A
into channel 540 is prevented when the pin blocks ~he ape~ture 804 in the wall of the sleeve (Fig. 50) and as the sleeve 800 blocks feed channel 440. Flow of polymer A into channel 540 is permitted when the pin is withdrawn ~ufficiently to unblock aperture 804 in the wall of the sleeve or when the sleeve is withdrawn sufficiently to unblock the ~orward end 542 (Fig. 53A) of feed channel 440.

Thus, each polymer flow passageway 460, 480, 500 and 520 terminates at an exit orifice and the orifices are located close to each other and to the tip of the nozzle cap 438. The central channel 54U of the inner nozzle insert ~.
- ~9 _ ~5~t7 .

shell 430, together with the orifice~forming ends of the tapered, conical portions 544 at the forward end of each of the shells, form the central channel 546 of the nozzle, and each of the annular exit orifices 462, 482, 502 and 522 of the polymer flow passageways communicates with the central channel 546 of the noz71e in a central channel combining araa at a location close to the open end thereof.

It is highly desirable to have unifo~mity o~ polymer temperature around the annular flow passageway for each polymer. Lack of annular temperature uniformity causes lack of viscosity uniformity which, in turn, leads to non-uniform flow of the polymer, producing a deleterious bias of the leading edge of tha internal layers. Angularly offsetting the nozzle shell feed channels from each other, as shown in Fig. 49AA, and as described above, angularly distributes around the nozzle the heat from the entering polymer flow streams, promoting annular temperature uniformity and correlative uniformity of polymer flow. A ~econdary benefit o angularly offsetting the nozzle shell feed channels ia a substantial radial pressure balance of polymer flow streams on each nozzle assem~ly.

Particular aspects of the nozzle shells will now be described. Referring now particularly to Figs. 49A, 49AA and 50-54A, inner ~eed channel 440 in inner shell 430 is pre~erably a keyhole pasqageway (Fig. 54) which runs axially through the inner shell and communicates along its axial length with central channel 540 of the inner shell. The keyhole passageway running axially in communication with the central channel terminates at its forward end 542 in a forward terminal runout wall which is rounded so that the polymer material washes out of the keyhole and does not accumulate in any sharply cut corner. Reyhole exit port 407 in the first shelf 382 of feed block 294 communicates directly with a matched key slot entrance port 450 to inner feed channel 440. Key slot port 450 has a 5 mil chamfer to ensure proper alignment with exit port 407 in the feed ~5~5~ 1 block. The obloround exit port 411 in the first shalf of the feed block (Fi~s. 41, 42 and 42A) communicates directly with a matched obloround entrance port 452 cut into the rear face of the inner shell, and which communicates directly with an obloround feed channel 442 (.093 wide by .251" long) which runs axially through the approximately rear longitudinal half of the inner shell a uniform distance from the shoulder 548 (Figs. 51 and 53A) and through the pilot 549 at least approximately ~298 inch from the axial center of the inner shell. The obloround feed channel 442 terminates at its forward end in an obloround forward exit port, whose upper portion communicates directly with a cut-away area 550 in the outer surface of the inner shell, and whose lower portion terminates in a forward terminal runout wall portion 551 ~Fig. 53A) having a rounded sloping surface to avoid material ac~mulation there. Cut-away area 550 is of the same open cro~s-sectional area as the forward end of the feed channel.
Wall portion 551 is preferably at a 45 angle or less, as me~sured rom the central axis of the shell. The inner shell has a forwardly pitched cut circumferential forward edge or wall 530 having a low point adjacent obloround forward exit port of channel 442 and a ~igh point disposed 180 from ~he exit port. The obloround feed channel exit port and the obloround feed channel runout which exit adjacen~ the low point of wall 530 communicate directly with a primary melt pool cut-away section 552 formed and defined at its rear boundary ~y wall 530, at its forward boundary by the rounded rear wall 529 of eccentric choke ring 524 and on it~ lower boundary by the cylindrical inner axial base wall 553 cut into the periphery of the inner shell (Fig. 53A). Eccentric choke ring 524 is disposed perpendicular to the axis of the inner shell. The width o~ choke 524 is narrower adjacent the obloround exit port and runout than it is at the 180 oppo~ite si,de of the shell adjacent the high point of wall 530. When viewed in cross-section, eccentric choke 524 is circular. ~owever, the center point of the circle it ~orms is eccentrically located relative to the axis oF the shell such that the height of the radial protuberance (as shown in \~

~:256~;7 Fig. 51) is greater in the area adjacent the obloround exit port and runout than it is adjacent the high point of the elliptical wall 530. The inner shell 430 also has a restricter in the form of a concentric choke 526 concentrically disposed perpendicular to the axi~ of the inner shell. The width of the concentric choke 526 is the same about its circumference and the radial distance from the axis of the shell to its outer surface i5 the same around the circumferenGe of the shell (Figs. 52 and 54). The walls 533, 534 of the rsspective eccentric and concentric chokes, together with the cylindrical inner axial base wall 553 form a secondary melt pool cut away section 554, 360 about the inner shell (Fig. 51). Forward of the concentric choke 52 is a final melt pool cut away section 555 formed by the forward wall 537 of the concentric choke, the cylindrical inner base wall 553 of the inner shell, and the frustoconical base wall 556 at the forward portion of the shell. The in~ersection of frustoconical wall 5;6 with central channel 540 in shell 430 has been ground to a flat a~nulus 601 (shown in exaggerated form in Fig. ;3A~, lying in a plane perpendicular to the longitudinal axis o~ the shell, to avoid breakage and wear which may occur when the acute angle intersection is a sharp edge. In the pref erred embodimen~
the radial thickn~ss of the flat is 5 mils. The radial distance of the base wall 553 from the central axis of the shell is the same for the primary and secondary melt pools as well as for the rear portion o final melt pool section 555.

A~ shown in Figs. 49, 49A, 49AA and 50, inner shell 430 is telescopingly seated in a close tolerance fit within the bore, generally designated 558 (Fig. 57A), of third shell 432 such that the rear face 559 o~ the third shell abuts against the forward face 560 (Figs. 51 and 53A~ of the inner shell's shoulder 54~. The cylindrical wall portion of the ~ore 558 in the third shell 432 cooperates with the walls o the melt pool cut away sections and forms the radially outer boundary wall of the primary melt pool 528, and of the secondary melt pool 532, of polymer D. The cylindrical wall ~2~

portion of bore 558 and the~ inner surface of the tapered, frustoconical portion 544 of shell 432 form the outer wall of a cylindrical portion of, and of the tapered conical portion of, the final melt pool 536 of polymer D (Figs. 50 and 57A).

The third shell 432 of the nozzle assembly of this invention is shown in Figs. 50 and 55 57A. Obloround entrance port 454 communicates directly with a matched obloround exit port 415 in the second shelf 384 of the feed block 294 nozzle~receiving chamber 380. Port 454 communicates directly with a like obloround feed channel 444 ~.~50 inch wide by about .109 inch high) which runs axially through the approximate rear longitudinal half of the third shell, the axis of channel 444 being located approximately .460 inch measured from the axial center line of the third shell. The third shell has a ~orwardly pitched cut circumferential orward edge or wall 510 (Fig. 55) having a low point adja ent the forward exit port of channel 444 and a hi~h point disposed 180 from the exit port. Feed channel 444 terminates at its forward end in an obloround forward exit port which communicates directly with a primary melt pool cut-away section 561 and defined at its rear boundary by the wall 510, at its forward boundary by the rear wall 509 of the eccentric choke 504 and on its lower boundary hy the cylindrical inner axial base wall 562 cut into the periphery of the third shell. The eccentric choke 504 has its circumferential center line in a plane perpendicular to the axis of the third shell. The wid~h of the choke is uniform around its circumference. When viewed in cross-section ~see Fig. 57A), eccentric choke 504 is circular, but the center of the circle it ~orms is eccentrically located relative to the axis o~ the third shell, such that the height of the radial protuberance ~as also shown in FigO 55) relative to the base wall 562 is greater in the area adjacent th@ obloround exit port than it is adjacent the high point of the elliptical wall 510. The third shell 432 also has, adjacent to but axially forward o~ eccen~ric choke ring 504, a restricter in the form of a concentric choke ring 506, concentrically - ~3 -2~7 disposed relative to, and having a plane through its circumferential center line perpendicular to, the axis of the third shell. The width of the concentric choke 506 is the same around its circumference and the radial distance from the axis of the shell to the outer surface of the choke is uniform. The walls ;13, 514 of the respective eccentric and concentric chokes, together with the base wall 562 form a secondary melt pool cut away section 563, 360 about the shell. The radial distance of the base wall 562 from the central axis of the shell is the same for each of the primary and secondary melt pools. Forward of the eccentric choke 504 is a final melt pool cut away section 564j formed by the forward wall 517 of the concentric choke 506, the cylindrical inner base wall 565 portion of the shell and by the frustoconical base wall 566 at the forward portion of the third shell. To add strength to the forward portion of the shell, the radial distance of the base wall 565 ~rom the central axis of the shell is greater than the distance of base wall 562.

Referring again to ~igs. 49, 49A and 50, the third shell 432 is telescopingly seated in a close tolerance fit within the bore, generally designated 567, of second shell 43~ such that the rear face 568 of the second shell abuts against the ~orward face 569 of the third shell'~ shoulder 570. The cylindrical wall portion 602 of the bore 567 in the second shell 434 forms the radially outer boundary wall of the primary melt pool 508, and of the secondary melt pool 512, of polymer C. The cylindrical wall portion 602 of bore 567 and the inner surface 603 of the tapered, ~rustoconical por~ion 544 of shell 434 form the outer wall of a cylindrical portion of, and of the tapered conical portion of, the final melt pool 516 of polymer C.

The second shell 434 of the nozzle assembly of this invention is shown in Figs. 58 through 62B. Obloround entrance port 456 communicates directly with a matched obloround exit port 417 in the third shelf 386 of the feed block 294 nozzle receivin~ chamber 380. Port 456 communicates directly with a like obloround feed channel 446 (.093 inch high by .250 inch wide) which runs axially through the approximately rear longitudinal half of the shell from the rear face 568 of the shell, through the shoulder 571 and through the pilot 572 at a downward angle directed toward the axis of the shell to the forward end of the ~eed channel.
The upper end portion of tha exit port of feed channel 446 communicates directly with a cut-away area 573 in the outer surface of the shell. The lower portion of the feed channel obloround forward exit port terminates in a forward terminal run-out wall portion 605 having a rounded, sloping surface to avoid material accumulation therein. As in the case o the inner and third shells, the second shell likewise has an eccentrically cut circumferential forward edge or wall 490.
Wall 4gO has a low point adjacent the obloround forward exit port of channel 446 and a high point disposed 180 from the exit port. The exit psrt and run-out communicate directly with a primary melt pool cut-away section 574 formed and defined at its rear boundary by wall 490, at its forward boundary by the rounded side wall 489 o~ the eccentric choke ring 484, and on its lower boundary by the cylindrical inner axial base wall 575 cut into the periphery of the shell.
Eccentric choke 484 is disposed p~rpendicular to the axis of the shell. The width of choke 484 is narrower adjarent exit port and run-out than it is at the 180 opposite side of the shell adjacent the high point of wall 490. When viewed in cross-section, eccentric choke 484 is circular. ~owever, the center point of the circle it forms is eccentrically located reiative to the axis of the shell such that the height of the protruding choke wall (as shown in Fig. 58) is greater in the area adjacent the obloround exit port and run-out than it is ad~acent the high point of the elliptical wall 490. The second shell 434 also has, adjacent to but axially orward of e~centric choke 484, a second flow restricter in the form of another eccentric choke 486 disposed perpendicular to the axis of the shell. The width of eccentric choke 486 is non-uniform and like eccentric choke 484 is narrower in the _ 5 _ portion of the circumference of the shell which is aligned with the exit port.

When viewed in cross-section, eccentric choke 486 is circular. ~owever, the center point of the circle it forms is eccentrically located relative to the axis of the shell such that the height of the protruding choke wall relative to the base wall 575 ~as shown in Fig. 58) is greater on the side of the shell where th~ feed channel 446 is located than it i5 on the side where the forward portion of the wall 490 is located. The walls 493, 494 of respective eccentric chokes 484, 486, together with the base wall 575, form a secondary melt pool cut away section 576, 360 about the shell. Forward of choke 486 is a final melt pool cut away section 577, formed by forward wall 497 of choke 486, the -cylindrical base wall 575 portion of the shell and by the frustoconical base wall 57B. The radial distance of base wall 575 from the central axis of the shell i~ the same for the primary and secondary melt pools and for the rear portion of the final melt pool.

Referring ~gain to Figs. 49, 49A and ;0, the second shell 434 is telescopingly seated in a close tolerance fit within the bore, generally designated 579, of first chell 436 such that the rear face 580 of the first shell abuts against the forward face 581 of the second shell'c shoulder 571. The cylindrical wall portion 606 of the bore 579 in the first shell 436 forms the radially outer boundary wall of the primary melt pool 4~8, and of the secondary melt pool 492, of polymer E. The cylindrical wall portion 606 of bore 579 and the inner surface 607 of the tapered, frustoconical portion 544 of shlell 436 form the outer wall of a cylindrical portion of, and o:f the tapered conical portion of, the final melt pool 496 of polymer E.

The first shell 436 of the nozzle assembly of this invention is sho~n in Figs. 65 through 70A. Obloround entrance port 458 communicates directly with a matched exit la,g - ~ 6 -port 418 in the front Eace 388 of the feed block 294. Exit port 418 is the exit of feed throat 402 which is cut out of the periphery of feed block 294. The radially outer wall of eed throat 402 is the inside surface of the bore in the runner block into which is inserted the feed block 294. Port 458 communicates directly with a like obloround feed channel 448 (.093 inch high by .250 inch wide) which runs axially through the approximately rear longitudinal third of the shell from the rear face 580 of the shell, through the shoulder 582 and through the pilot 583 at a downward angle directed toward the axis of the shell to the forward end of the feed channel. The upper end portion of the exit port of feed channel 448 co~municates directly with a cut-away area 584 in the outer surface of the shell. The lower portion of the feed channel obloround forward exit port terminates in a for~ard terminal run-out wall portion 609 having a rounded, sloping surface to avoid material accumulation therein. As in the case of the previously mentioned shells, the ~irst shell has an eccentrically cut circumferential forward edge or wall 470~ Wall 47C has a lo~ point adjacent the obloround forward exit port of channel 448 and a high point disposed 180 from the exit port. The exit port and run-out communicate directly with a primary melt pool cut-away section 585 formed and defined at its rear boundary by wall 470, at its forward boundary by the rounded side wall ~69 of the eccentric choke ring 464, and on its lower boundary by the cylindrical inner axial base wall 586 cut into the periphery of the shell. Eccentric choke 464 is disposed perpendicular to the axis of the shell. The width of choke 464 is narrower adjacent exit port and run-out than it is at the 180 opposite side of the shell adjacent the high point o~ wall 470. When viewed in cross~section, eccentric choke 464 is circular. ~owever, the center point of the circle it forms is eccentrically located relative to the axis of the shell such that the height of the protruding choke wall (as shown in Fig. 65) is greater in the area adjacent the obloround exit port and run-out than it is adjacent the high point of the elliptical wall 470. The first shell 436 also ~9 has, adjacent to but axially forward o eccentric choke 464, a second flow restricter in the form of another eccentric choke 466 disposed perpendicular to the axis of the shell.
The width of eccentric choke 466 is non-uniform and like eccentric choke 464 is narrower in the portion of the circumference of the shell wllich is aligned with the exit port. When viewed in cross-section, eccentric choke 466 is circular. However, the center point of the circle it forms is eccentrically located relative to the axis of the shell such that the height of the protruding choke wall relative to the base wall 586 (as shown in Fig. 65) is greater on the side of the shell where the feed channel 448 is located than it is on the side where the forward portion of the wall 470 is located. Eccentric choke 464, in the preferred embodiment, is 10 mils radially larger than eccentric choke 466. The walls 473, 474 of respective eccentric chokes 464, 466, together with the base wall 586, form a secondary melt pool cut away section 587, 360 about the shell. Forward of choke 466 is a final melt pool cut away section 588, formed by fo~ward wall 477 of choke 466, the cylindrical base wall 586 portion of the shell and by th2 frustoconical base wall 589. The radial distance of base wall 586 from the central axis of the shell is the sama ~or the primary and secondary meLt pools and for the rear portion of the final melt pool.
Two holes 590 partially drilled into the shoulder 582 of shell 436 each receive the end portion of an anti-rotation pin 5gl (see Pigs. 31 and 49~ which extends through a channel bored in the runner and which serves to locate, and prevent rotation of, the shell.

The cone tip 601 of each of the four nozzle shells 430, 432, 434 and 436 is rounded to a radius of approximately 5 mils. This makes the tip less susceptible to fracture from melt stream pressure and from damages during handling of the shells and their assembly.

The first shell 436 is telescopingly seated within nozzle cap 438. The rear wall of shoulder 592 of the nozzle ~3O
~8 ~ ~ ~ 6 ~J~ ~

cap abuts against the forward wall of the firsS shell shoulder 582. The inner cyLindrical surface 610 o~ the nozzle cap forms the outer boundary of the primary melt pool 468 and the secondary melt pool 472 and the rear portion of the final melt pool 476. Tle inner conical wall 593 of the nozzle cap forms the outer boundary of the conical portion 478 of the final melt pool 476. The length of the conical wall 593 of the nozzle cap is longer than any of the frustoconical walls of the shells, and the conical portion of the nozzle cap terminates at its forward end in a nozzle tip 594 having a centrally located channel S9S which communicates directly with the mouth or gate 596 at the forward most tip of the nozzle cap. The diameter of channel 595 is smaller than that of the sprue of the mold cavity. Pin 834, which is included in the nozzle valve means of the present invention~
may be received within channel 595, i~ a close tolerance slip ~it, at the end o~ each injection cycle for the purposes of assisting in preventing the flow of polymer B at ~he end of ea~h injection cycle and clearing or purging substantially all polymeri~ material from the nozzle central channel 546 and channel 595 into the injection cavity at the end of each injection cycle.

The nozzle shells are assembled and placed in the injection mach~ne in the following manner. First~ the feed block is seated within bore 822 of runner block 288. This is done by first seating piston rings 424 in groovas 425 of the feed bloclc and compressing the rings as the feed block is inserted into bore 822. Next, the feed block is properly oriented within the bore by placing sha~t 156l of locator pin 154 within hole 158 in the side of the feed block (see Figs.
29C, and 45-45~). Once the feed block is properly oriented and seated within bore B22, then, "O" ring~ 597, preferably made of soft copper, are inserted in seats 598 which are cut in the shoulder of each nozzle shell and the nozzle cap. The ~O" ring is preferably formed from 22 gauge annealed copper wire having a cross-section 30 mils in diameter. Then, a position-alignment locator pin 611 is inserted in~o the .

~L2~ 5~

locator pin hole in the rear face of the inner shell 430, the third shell 432 and the second shell 434, and the shells are individually serially inserted into and are seated within a portion of nozzle receiving chamber 380 at the forward end of feed block 294, more particularly, within the portion defined by first shelf 382 and first step 383 (Figs. 41 and 43). Next, pin 611 in third shell 432 i respectively seated within hole 422 in feed block second shelf 384, and then the third shell is seated within the feed block receiving chamber portion formed by second shelf 384 and step 385. Next, pin 611 in second shell 434 is seated within hole 421 in feed block third shelf 386 and the second shell is seated within the chamber portion formed by third shelf 386 and step 387.
Pin 611 in first shell 436 is then seated within hole 420 in front face 38~ of feed block 294 and the rear face of the first shell is abutted against the front face of the feed block. Next, a sealing ring 597 is seated in a seat in the rear face of nozzle cap 438. The nozzle cap ~38 is then slipped over the first shell and moved rearward until its rear face abuts th~ flange 582' o~ first shell 436. Next, keeper plate 176 (Figs. 29A, ~9A', an~ 29B) is slipped over the nozzle cap, and, by means of bolts 177 the plate is secured to runner block 288. 301ts 177 are drawn tight to compress seal ring 597 on the first shell and the nozzle cap. This lock up drives the rear face o~ the nozzle cap against flange 582' of the first shell 436, drives the rear ~ace of that shell against front face 388 of feed block 294, permanently seats the first shell and nozzle cap respectively against fixed shoulder 822' in the runner block, and, as stated seats the first shell against the front face 388 of the feed block. Finally, lock ring 824 is tightened to compress the ~0" rings to assure a metal to metal seat abutment between each of the shells, nozzle caps and feed block. Tightening the lock ring also prevents axial movement o the fead block within runner block bore 822.

The nozzle cap and each of the nozzle shells should be formed from a material having dimensional stability at the ~32~
~ ~ ~

2~t~
elevated temperatures to which they are sub~ected in the operation of the machine, on the order of 400 - 430F. The nozzle cap, the first nozzle shell 436 and the inner shell 430 should be formed from a material which also has high wear resis-tance. The second and third nozzle shells 434 and 432 should be made from a material which also has good ductili~y and elongation. Nozzle shells 430, 436 and nozzle cap 438 have been made from steel conforming to Unified Numbering System for Metals and Alloys No. T 30102. Suitable nozzle shells 432 and 434 have been made from Viscount 44 prehardened hot work steel H-13 ~Latrobe Steel Co.) having a typica] analysls: C 0.4; Si 1.0; Mn 0.8; Cr 5.0; Mo 1.2; V 1Ø Most preferably, all the nozzle shells 430, 432, 434 and 436, and nozzle cap 438 t are made from VascoMax C-300 steel having a nominal analysis: Ni 18.5%; Co 15 9.0%; Mo 4.8%; Ti 0.6~; Al 0.1%; Si 0.1%; max.; Mn 0.1% max.; C
0.03%; S 0.01% max.; P 0.01% max.; Zr 0.01% B 0.003%. The pin 834 and sleeve 800 should be formed from a material having high wear resistance and dimensional stability. Sleeves have ~een made from D3 steel conforming to Unified Numbering System No. T
20 30403 . The sleeve is made from D-3 steel, most preferably VascoMax C-~50 steel having a nominal analysis: Ni 18.5%; Co 7.5%; Mo 4.8~; Ti 0.4%; Al ~ ; Si 0.1% max.; Mn 0.1%.; C 0.03 max.; S 0. al% max.; P 0.01% max.; Zr 0.01~; B 0.003%. Suitable pins are manufactured by D-M-E Co. (2911 Stephenson Hwy., Madison 25 Heights, Michigan 98071~ as e;ector pins, Cat. No. Ex-ll-M18.

Figs. 75, 76 and 77 respectively are a side elevation, a cross-section and an end view of an exemplary nozzle shell showing letter designations corresponding to those of Table 1 for the dimensions of the stated parts of the preferred embodiment of outer shell 436, second shell 434, third shell 432, lnner shell 430 and nozzle cap 438 of nozzle assembly 296. In Table 1, all ;
dimensions are in inches except S and T which are degrees.

*Trademark.

~ 133 -- . : . .
, ' .~

TABLE I

NOZZLE SHELL DIMENSIONS

OUter SeCOnd Third Inner NOZZ1e She11 She11 Sh811 She11 CaP

A 3 ~1370 3 - 3774 3 - 6979 3 - 9928 2 7991 B 2 ~ 2815 2 ~ 413 2 - 787 3 ~ 300 2 ~ 177 C 1-9640 2~344~ 2O7691 3.125 1~7~17 D 2.101 2~163 2-625 2~862 ~~~
E 1~945 2~042 2-574 2~702 ~~~
F 1~745 1~843 2-275 2~452 ~~~
G 1~545 1~718 2~078 2~311 ~~~
0~795 1-218 1-578 1~811 ~~~
I 0-6251 0~3751 0-3751 0~3751 0~593 J 0~3255 0-0255 0-0255 0~0255 ~~~
R 1~327 1.500 1.860 2-093 ~~~
L 1 ~ 6251 1 - 1876 0 - 7501 0 - 2504 2 - 0007 M 2~39a9 1-~179 1-2809 0~8439 ~-436 N 2-3255 1-654 1D216 0-7795 ~~~
O 2-000 1.6~47 1-1~72 0-7497 2-309 P 1.9000 1 - 5~0 1 - 0535 0 ~ 6897 ~~~
Q 1. 800 1. 365 0 ~ 9R7 0 . 5897 0 ~ S00 R 1.800 1~365 0.907 0~5897 ~~~
S 33 25 15.50 ~~~ 45 T 42 30 22 13 ,. 50 60 U 0.250~ 0.2504 0.2504 0.2504 0.1563 V 0 . 0295 0 . ~3~3 0 - 0332 0 ~ 0173 ---W 1.8~0 1.500 1.0537 0-6647 ~~~
X 0 ~ 250 0 - 250 0 . 25~ 0 . 250 ---Y 0~093 0.125 0.1095 0.093 ---Z 0 . 952!; 0 . 7345 0 . 5145 0 ~ 2965 ---AA 0-462 0-375 0~281 0.344 ---BB 0 . 799 0 . 650 0 ~ 487 --- ---CC 0.090 0.09~ 0.090 0.~90 ---DD 0 . 003 ' 0 ~ 003 0 ~ 003 0 . 003 ~~~
EE 0.012 0.012 0.012 0.012 ---_ ~_ ~2~

TABLE I

NOZZLE S~ELL DIMENSIONS (Continued) Outer Second Third Inner Nozzle Shell She'l Shell Shell CaP

FF 0.063 0.063 0.063 0.063 ---GG 0.0075 0.0075 0.0075 0.0075Q.0075 0.120 ~ 0.030 0.030

3 1 0 0 - -where:
A = Overall length Length from rear face of shell to beginning of frustoconical outer surface C = Length from rear face to beginning of frustoconical inner bore surface D - ~ength from rear face to forward wall of second choke E - Length from rear face to rear wall of second choke F - ~ength from rear face to forward wall of first choke G - Length from rear face to rear wall of first choke - Length from. rear fa~e to start of primary mel~ pool and termination~of top edge of flow channel I = Length from rear face to forward face of shoulder J = Depth of groove for seal ring - Length from rear face to location of termination point of elliptical edge of primary melt pool L 3 Diameter of inner cylindrical bore M = Outside diameter of shoulder N - Inside diameter of seal ring groove O s Outside diameter of pilot P = Outside diameter of secon~ choke Q - Diameter of final melt pool cylindrical base wall at intersection with frustoconical surface R = Diameter o primary and secondary melt pool cylindrical ba~e wall S - Inside frustoconical surface angle ~degrees) ~56~'7 T ~ Outside frustoconical surface angle (degrees) U - Diameter of inside suri.ace at tip of forward end of the shell V - Offset dimension for center of eccentric choke W = Outside diameter of fir.st choke X ~ Width of feed channel Y = ~eight of feed channel Z ~ Location of axis of entrance port of feed channel AA & BB - Coordinate locations of locator pin CC - Corner radii at each location o~ choke and melt pool DD Radii break in sharp corners to eliminate stress areas EE = Corner radii to eliminate sharp edge FF = Diameter of hole to accept locator pin GG - Chamfer of inside bore to eliminate corner interference with shoulder Length oE sealing land Angular deviat~on from axial for feed channel center line, sloping downward from origin at rear of shoulder ~ igure 77A shows that in the preferred embodiment of the nozzle assembly or co-injection nozzle of this invention, an ima~inary line drawn from the leading lip to the trailing lip about ~he circumference of each pair of lips which form each of the respective first, fourth, second, and fifth n~rrow, fixed, annular exit orifices 462, 482, 502 and 522 (the third orifice for A layer material is not shown) of passageways 460, 480, 500 and 520, forms an imaginary cylinder whose imaginary wall completely surrounds the central channel substantially parallel to the axis of the co-injection nozzle central channel, generally designated 546. Projections of the respective mid-points about the circumfer.ence of the imaginary cylindrical surface of each orifice are re~erred to and shown as center lines 190, 192, 194 and 196 and which, in the preferred embodiments, are perpendic:ular the axis of the co-injection nozzle. The orifices sbown have an axial width which is uniform about the central c:hannel and they have a cross sectional area no grea~er t:han, and preferably less than that of the central ~l2 r~6~

channel. The central channel has a portion which coincides with the central channel 540 of inner shell 430, and extends forward through the channel portion of the nozzle assembly defined by the nozzle shell tips and by orifices 522, 502, 482 and 462. The nozzle central channel extends forward to the portion of the leading wall of passageway 460 which is designated 460' and which is shown extending diagonally downward from the leading lip 461 of orifice 462 toward the gate and the axis of the central channel, and the central channel coincides with channel 595 which runs forward through nozzle cap 438 to gate 596. The central channel pre~erably is cylindrical and has a uniform cross-sectional area throughout its length, or at least from the leading lip 461 cf the ~irst orifice to the trailing lip of the second orifice 502 or o~ the orifice most remote fro~ the gate (other than thiP third orifice or feed channel for the A layer m~terial). In Fig. 77A, the most remote orifice is the fifth orifice, 522. The nozzle central channel includes what is referred to as the combining area which i5 that portion o~
t~e central channel, preferably cylindrical, extending from the laading lip 461 of the first annular exit orifice 462 to the trailing lip of the annular orifice most remote. from the gate, here, trailing lip 523 of fifth annular exit orifice S~2. For a co-injection nozzle of a compa~able design for co-injecting three layers, the orifice most remote from the gate would be the second orifice 502~ In the combining ~area, the polymer streams combine into a combined flow stream for injection from the nozzle. For forming the thin walled container~ and articles of this invention, it is preferred that the combining area be as short as possible, that is, that the orifices be located as close to each other as possible and as close as possible to the gate, given the certain nozzle tip thicknesses and strengths ~e~uired for nozzle operating temperatures and pressures and given sufficient tip land lengths for sealing purposes, such as to prevent crO59 channel flow. Wherever it is located, the combining area for a five layer nozzle ~ill usually have an axial length of from about 150 to ahout 1500 mils, more often _ ~ ~7 from about 150 to about S00 mils. With respect to the preferred nozzle assembly schematically shown in Fig. 77~, the ~combining area~ preferably has a uniform cross-sectional area and has an axial length of from about lS0 to about lS00 mils measured to trailing lip 523, more preferably, from about 150 to about 500 mils. When the combining area extends to the trailing lip of the second orifice, preferably its axial length is from about 100 to about 900 mils, more preferably from about 100 to about 300 mils. It is believed that the closer the orifices are to each other, the more precise the control will be over the relative annular locations o the respective materials in the combined stream, and the easier it is to knit and encapsulate the C layer material. Although the combining area can be located anywhere in the central channel, for example, more removed from the gate than shown in the drawings, it is preferred that the first, and additionally the fourth, second and fith oriices be located as close as practically possible to the gate. It is believed that the closer the orifices are to each other and to the gate, the shorter will be the flow travel distance for the combined low stream to the gate and the greater will be the likelihood that the precise control exerted over the material streams or layers at the orifices and in the combining area will be maintained into the injection cavities and re~lected in the relative location~
and thicknesses of the respective layers and their leading edges in the formed articles. For forming the thin walled articles of this invention, preferably, the leading lip of the first orifice is within from about 100 to about 900 mils of the gate, more preferably within from about 100 to about 300 mils of the gate. A suitable orifice arrangement is one wherein the first orifice has its center line within from about 100 to about 350 mils, preferably about 300 mils from the gate, the second orifice has its center line within from about 100 to about 250 mils of the center line of the first orifice, l~nd the leading lip of the first orifice and the trailing Lip of ~he second oriice are no greater than about 300 mils apart. Another suitable arrangement is that wherein the trailing lip of the second ori~ice, or of the least proximate orifice relative to the gate, is ~rom about 100 to a~out 650 mils from the gate. Preferably the center line of the second orifice is within from about 100 to about 600 mils of the g2te. The axial length from the leading lip of the fourth orifice to the trailiing lip of the fifth orifice is preferably from about 100 to about 90U mils, more preferably from about 100 to about 300 mils. It is most desira~le to have the fourth, ~econd and fifth orifices as close together as possible. Pre~erably, the combining area has a volume no greater than about 5% of the volume of the injection cavity into which the combined polymer flow stream i~3 injected from the nozzle. A greater volume renders it difficult to blow a thin bottom container and wastes polymerlc material.

It is preferred that one or more of the nozzle passageways of this invention especially those having annular orifices be tapered, especially those whose materials are to be pressurized, to have rapid and uniform onset flow, and to thereafter flow at substantially steady conditions. A
tapered passageway adjacent the orifice is also advantageous because it facilitates rearward movement of polymer material in the passageway and therefore it facilitates decompressing and reducing or stopping flow through an orifice when a ram is withdrawn. It is particularly desired to utilize the tapered passageways and narrow annular orifices in cooperation with the valve means of this invention, especially with respect to intermittent flow processes such as those included in this invention, particularly with respect to starting and stopping the flow of a~ internal barrier layer and intermediate adherent layer materials. It is usually desired that the passageway for internal layer material sometimes referred to as the second passageway, be tapered particularly when the material is a barrier material and the location o~ its leading edge and its lateral location in the injected article is important. For such applications, it is also desired that the passageway for the outer layer material, sometimes referred to as the first passageway, be ~73 ~

~256~

tapered since the flow of that material affects the flow, thickness and location of th~e internal layer material. A
tapered passageway here means that the walls which define the confines of the portion of the passageway adjacent the orifice, here the leading or outer and trailing or inner walls which define the final melt pool, converge from a wide gap at an upstream location of the passageway, here at the beginning of the final melt pool, to a narrow gap at the exit orifice. Although it is preferred that the convergence be continuous to the orifice, the taper, as defined above, can be independent of the passageway wall geometry therebetween~
Thus, the orifice of a tapered passageway has a smaller cross-sectional gap than an adjacent upstream portion of the passageway. Although the taper may be provided by changing the slope angle of either the passageway outer or inner walls or both, it ie to be noted that the taper of the passageway is distinct from the shape of the frus~oconical portion o~
the shell. Employing a tapered passageway and utilizing pressurization oi the material in the tapered passageway adjacent the ori~ice creates a pressurized final melt pool of polymeric melt material such that when the orifice is unblocked~ there is a rapid initial flow uniformly over all points of the crifice and there is a sufficient supply of compressed material in the melt pool to substantially attain longer steady flow conditions. The rapidity and degree of uniformity of initial flow would be substantially less and there would be a significant drop-off in the flow volume into the central channel with a constant gap equal to the gap of the orifice determined by a line projected from the trailing lip perpendicularly through~the flow passageway. ~he ability to rapidly stop the flow through a non-tapered, non-constant gap passagleway would be significantly less than with a tapered passageway because the latter would have a substantially narrower gap.

As will be explained in connection with Fig. 77B and the Table below, a tapered, decreasing-diameter, frustoconical passageway enhances the polymeric material melt _ ~ _ ;2~i7 flow circumferentially around the narrowing conical shell portion and thereby assists in flow balancing the material about the conical tip prior to exiting the orifice.

Fig. 77B, a vertical cross sectional view through a hypothetical nozzle shows a tapered passageway formed by the leading or outer wall OW and the trailing or inner wall IW, tha latter being the outer surface of the frustoconical portion of a nozzle shell, say 436 in ~ig. 77A. Fig. 77B
shows the passageway axially divided into four sections designated I, II, IIl and IV and shows the dimensions from the axial center line of the nozzle to points on the inner wall at the divisions of the sections and the dimensions from the axial center line radially to a point on the same radius and on the outer wall. The dimensions shown in FigO 77B and a standard parallel plates channel flow equation for an incompressible isothermal purely viscous (non-viscoelastic~, non-Newtonian power law fluid known to those in the art, were used to calculate the values shown in the Table belowl where:

G - the geometrical factor for the design of the flow pa~sageway. This is an equivalent form of flow resistance.

~ P ~ the pressure.drop between two points measured either at the midpoin~s between the sections in the axial direction, or 180 apart in the azimuthal direction within the same section.

It is known that there is an increase in the resistance to flow of a polymeric melt material as it flows axiaLly forward through either a tapered gap or a constant gap passageway toward an orifice. This applies even though in eiach case the inner wall of the passageway is the outer surfiace of a frustoconical portion of a nozzle shell of this inventionq Thi~ is due to the decreasing diameter of the frustoconical portion which reduces the circumference of the flow passage. Fig. 77B and the Table below show that given .

. , .

the small oriflce gapt a tapered passageway in cooperation with the inner frustoconical surface enhances the flow of polymer melt material in th~ circumferential direction about the frustoconical shell por1:ion and provides greater flow balancing of the material than would a constant gap in cooperation with the same inner frustoconical surface and having the dimensions of the orifice. This can be seen by comparing the value of G azimuthal for a tapered passageway with G azimuthal for a passageway having a constant gap of the dimensions of the orifice gapO

TABL~

Tapered Constant Gap Passageway Passageway Section .~xialAzimuthal hxial Azimuthal Direction DirectionDirection Directlon G ~P G ~ G ~ G ~P

In the preferred practice of the invention wherein all polymer streams flow in balance, each of the polymer streams is maintained at a temperature at which the pvlymer is fluid and can flow rapidly through the apparatus.
Although any suitable heating system can be employed to bring and maintain the polymer streams to the desired temperature, preferably the polymers in their flow channels are maintained at the desired tamperature by conduction from the metal forming and surrounding the channels~ The metal in turn is maintained at its temperature by a hot fluid, such as oil, passing through flow channels suitably located near the polymer flow channels. In the previously-described apparatus, oil which has been heated to an appropriate temperature, preferably in the range of from about 400F ~o 420F, usually about 410F simultaneously enters the left i2~7 flow circumferentially around the narrowing conical shell portion and thereby assist~s in flow balancing the material about the conical tip prior to exiting the orifice.

Fig. 77B, a vertical cross-sectionaL view through a hypothetical nozzle shows a tapered passageway formed ~y the leading or outer wall OW and the trailing or inner wall IW, the latter being the outer surface of the frustoconical portion of a no2zle shell, say 436 in Fig. 77A. ~ig. 77B
shows the passageway axially divided into four sections designated I, II, ~II and IV and shows the dimensions from the axial center line of the nozzle to points on the inner wall at the divisions of the sections and the dimensions from the axial center line radially to a point on the same radius and on the outer wall. The dimensions shown in Fig. 77B and a standard parallel plates channel flow e~uation for an incompressible isothermal purely viscous (non-viscoela tic), no~-Newtonian power law ~luid known to those in the art, were used to calculate the values shown in the Ta~le below, where:

G ~ the geometrical factor for the design oF the flow passageway. This is an equivalent form of flo~
resistance.

~ p a the pressure drop between two points measured either at the midpoints between the sections in the axial direction, or 180 apart in the azimuthal direction ~ithin the same section.

It is known that there is an increase in the resistance to flow of a polymeric melt material as it flows axially forward through either a tapered gap or a constant gap pass~geway toward an orifice. This applies even though in each case the inner wall of the passageway is the outer surface of a frustoconical portion of a nozzle shell of this invention. This is due to the decreasing diameter of the frustoconical portion which reduces the circumference of the flow passage. Fig. 77~ and the Table below show that given ('(( ~ t-~

the small orifice gap, a tapered passageway in cooperation with the inner frustoconical surface enhances the flow of polymer melt material in thle circumferential direction about the frustoconical shell portion and provides greater flow balancing of the material than would a constant gap in cooperation with the same inner frustoconical surface and having the dimensions of the orifice. This can be seen by comparing the value of G azimuthal for a tapered passageway with G azimuthal for a passageway having a constant gap of the dimensions, of the orifice gap.

TABLh ~apered Constant Gap Passageway Passageway Section Axial AximuthalAxial Azimuthal Direction DirectionDirection Direct~on G ~P G ~ G ~P

In the preferred practice of the invention wharein ali polymer streams ~low in balance, each of the polymer streams is maintained at a temperature at which the polymer is fluid and can flow rapidly through the apparatus.
Although any suitable heating system can be employed to bring and maintain the polymer streams to the desired temperature, preferably the polymers in their flow channels are maintained at the desired temperature by conduction from the metal forming and surrounding the channels. The metal in ~urn is maintainecl at its temperature by a hot fluid, such as oil, passing through flow channels suitably located near the polymer f].ow channels. In the previously-described apparatus, oil which has been heated to an appropriate temperature, preferably in the range of from about 400F to 420F, usually about 410F simultaneously enters the left ~:5~5t~

side of the rear injection manifold and the le~t side of the forward manifold, passes once horizontally through their respective widths in channels 309 and 311 and exits their right side into a manifold plate (not shown) which directs it to ram block 228. The oil enters the ram block's lower right side, makes three passes through channels 310, and exits through its upper left side. Each pass through the ram block is at a different level and through a different combination of the channels. The exit oil enters a heated reservoir (not shown) for recycling.

; The runner system, including the runner extension, has a three-20ne oil heating sy.tem (see Figs. 29, 30, 31).
The first is a one-pass system for the runner extension wherein, at.the twelve o'clock position of its central section 279, heated oil transferred from a reservoir through m nifold 157 (Fig. 29) and through a pipe 159 connected thereto and to oil retainer sleeve 972, enters the rearmost of annular channels 277, is split and flows clockwise and counter-clockwise downward around the runner extension, and exits at the six o'clock position in the forwarZ direction through a notch 277A into a forward adjoining annular channel 277 where the oil is again split and flows upward to the top and forward through another notch 277A. The oil follows a similar forward path through all channels and exi~s the bottom of the frontmost one through a pipe 277B (shown broken away) which directs it to an entrance (not shown) in bottom oil manifold 277C bolted to runner 288. From manifold 277C
the oil passes upward through the runner out through two holes 277D (Fig. 31) similarly positioned forward of the runner extension.front face 952, to a top manifold cover 277E
(shown broken away) on top of thç runner (see Figs. 29, 29C), which passes the oil to a heater for reheating the recycling through the first zone. The second zone or system is comprised of peripheral oil channels 277F which run along the rear and front faces of the runner block (see Fig. 31). The oil enters bottom oil manifold 277C through a port 160 for a channel 162 which through cross channels (not shown) directs ~2~

the oil to oil channels 277F which in turn direct the oil upwardly through channels 277F to top oil manif`old 277E, which directs it to a reservoir for reheating and from which it is transferred through a pipe (broken away) connected to port 160 for recycling through the second zonaO The oil for the third zone or system enters bottom oil manifold 277C
through a port 164 for a channel 166 which, through cross channels (not shown) directs the oil to oil channels 277F
which in turn (Fig. 30), direct the oil upwardly through the oil channels 277G, to a common discharge (not shown) at the top of runner 288, which directs the oil to a reservoir (not shown) for rehaating and from which it is transferred through a pipe (broken away) connected to port 164 for recycling through the third zone.

It will be understood by those skilled in the art that any suita~le oil flow path and direction can be employed~

A conventional oil heating system (not shown) is employed in injection cavity bolster plate 950 for heating injection cavities 102.

The Valve Means, Drive Means and Mounting Means he Sleeve The structure comprising the noz~le valve me~ns or valve means included within the co-injection nozzle means of this invention, and associated drive means for the valve means wil.l now be described in greater detail, having reference to Figs. 78-105. $he valve means includes hollow ~leeve 800 which is comprised of an elongated tubular memb~r 802 (shown foreshortened), having an internal axial polymer flow passageway or bore 820, having a wall 808 and at least Gne port 804 in the wall at its forward end portion 806 and communicating with passageway 820, and having a back end portion shown in the form of a frustoconical mounting flange portion 810 which con~ains pressure relief vent hole 811.

1~

Sleeve 800 has a mouth 812 defined by an annular tapered lip 814 at its forward end, and an opening 8L6 in its rear face 818. The sleeve and mouth are adapted to provide a polymer stream orifice in communication with the central channel at least adjacent the trailing lip of the second or fourth orifices. In the preferred embodiment, the thickness of the wall 80a of the ~leeve is 47 mils, the outer diameter of the sleeve is 250 mils, the tapered lip 814 is at a 45 angle, and the axial distance from the mouth 812 of the sleeve to the intersection of the taper with the outer surface of ~he sleeve is 47 mils. Mouth 812 and opening 816 communicate with axial bore 820 which runs the length of the sleeve.
Sleeve 800 is mounted in the apparatus of this invention for reciprocal movement through the respective central channels 390 of feed block 294 and 546 of nozzle assembly 296. There is a close tolerance slip fitting between the internal diameter of the feed block central channel wall 391 and the outer surface of sleeve wall 808 of from about .0005 to abo'ut .0013 inch, and between the internal diameter of the nozzle assembly inner shell central channel 540 and the outer surface of sleev~ wall 808 of from about .0002 to abou~ .001 inch. Slip fitted about the circumference of sleeve 800 and mounted within bore 379 of the axially extending feed block threaded extension 378 are two annular sealing rings 819 (see Fi~. 42A) for preventing polymeric material from being dragged rearward on the sleeve and thereby being pulled rearward out of feed block 294 when the sleave is reciprocated in the r~arward direction. ~olding sealing rings 819 in place within threaded extension bore 379 is a sealing riny retaining cap 821 threaded onto extension 378.
Feed bloclc 294 is retained in axial position in bore 822 of runner block 288 by a lock ring 824 threaded within tbreaded bore 826 (see Figs. 30, 31). As shown in Fig. 80, the frustoconlcal mounting flange portion 810 has two holes 828 bored axially therethrough for receiving shoulder screws 830 (~ig. 96) which pass through shims 831 and spatially mount the sleeve~ rear face 818 onto the forward face of suitable mounting and driving means, herein shown in the preferred l~

~ 25~ 7 form of a sleeve shuttle, generally designated 860 (see Figs.
88-92, 95-97, 99 and 100-103).

rrhe Pin -Sleeve ~ore 820 is adapted to carry additional nozzle valve means or valve means, preferably ln the form of an elongated solid shut-off pin 834 ~shown foreshortened) (Fig. 81), preferably having a pointed tip 836 at the forward end of its shaft 837, and a protruding annular head 838 at the rear end of shaft back end portion 840~ In the preferred embodiment, the diameter of shaft 837 of pin 34 is 156 mils, the tip 836 is conical at a 45 angle, and the axial distance from the point of the tip to the intersection of the conical surface of the tip with the cylindrical surface of shaft 837 is 78 mils.

Pin 834 is mounted in the apparatus of this invantion for reciprocal ~ovement within and through the bore of sleeve 800 by suitable mounting means which comprise a pcrtion of the driving means of tAis invention. The sleeve is mounted in the nozzle central channel, and the pin is mounted within the sleeve bore in a close tolerance slip fit sufficient to prev2nt a significant accumulation or passage of polymeric material between the slip fit sur~aces. The amount of material in the plane of an orifice or in ~he port of the sleeve is not considered significant within this context~ Pin 834 is adapted to have head 338 seated in a tight slip fit within a sea 842 cut into a suitable mounting and driving means preferably comprising a pin shuttle 844 (shown in Figs. 82-87, and 97). Pin shuttle 844 is a solid rectangular-like member having attached to each of its sides suitable means, such as one of a pair of mounting ears 846 cocked at an angle, for cooperatively providing the ~huttle with sliding reciprocal movement within cooperative, angled cam guide slots 848 o~ pin cam bars 850 (Figs. 85, 85A) which are included within the drive means of this invention.

Each pin cam bar 8!;0 of each pair of pin cam bars has cut through its thickness at its top end portion a hole 851 for connecting the bar to other portions of the drive means for effecting reciprocal movement of the pin cam bar.
~ach bar has cut through it and along its length, a sat of four equally spaced, equally angled, identical cam guide slots 848. Pin shuttle 844 is mounted between and on the pair of spaced, juxtaposed, parallel pin cam bars 850 by ears 846 which are slideably seated within the juxtaposed cooperative slots 848 in each juxtaposed cam bar (Figs. 86, 87). Two pairs of pin cam bars are employed in the apparatus of this invention, one pair positioned rearward of each perpandicular row of four nozzled assemblies. Each pair of juxtaposed slots 848 of the juxtaposed pin cam bars 850 receives the ears of a pin shuttle, which in turn holds a solid shut-off pin 834 which reciprocates within, and acts as valv~ means fos, one of the four nozzle assemblies ali~ned along one of the perpendicular row o~ nozzle assemblies in the eight-up nozzle assembly apparatus of this invention.
Each set o~ our solid pin shuttles 844 which straddle each p~ir of p$n cam bars 853 are mounted behind one of sleeve cam bars 856 lFigs. 93A, 94-98 and 100-102), such that each pin 834 passes through a sleeve shuttle 860, through a sleeve cam bar 856 on which the sleeve shuttle is mounted, and through a sleeve 800 which in turn, with the pin in it, passes through a feed block 294 and finally through a nozzle central channel 546. Movement of pin cam bars 850 and sleeve cam bars 856 substantially simultaneously and coordinatedly, vertically up and down in accordance with the preferred embodiment, drives or moves each group of associated sleeve and pin shuttles, and their sleeves and pins, substantially simultaneously as cooperative nozzle valve means and achieves substantially simultaneous valving action for each of the no~zle assemblies with respect to which they operate. T~is system provides substantially simultaneous, coordinated and controlled, substantially identical valving action with respect to each nozzle assembly in the eight-up nozzle assembly apparatus of this invention.

~7 ~5Çi~

The mounting and drive means of the injection molding apparatus also includes eight sleeve shuttles. Each sleeve shuttle 860 (Figs. 83-92) is comprised of a cylindrical member having an axial bore 862 extending through it for receiving and allowing reciprocal movement of solid pin 834. Each shuttle 860 includes a vertical slot 864 extending therethrough, defined by a pair of juxtaposed inner walls 866, and a knuckle 868 having the bore 862 running theretbrough. Sleeve shuttle forward face 872 has an annular chamber 873 cut axially therein and which communicates with bore 862 which in turn communicates with slQt 8~4. Face 872 also has two holes 867 therein for receiving the shoulder screws 830 (see Figs. 95, 96~ which mount the sleeve 800 onto the face of the sleeve shuttle. The sleeve shuttle outer surface has radially and axially extending lubrication reservoirs, generally designated 859 for accumulation grease fed to them and the interior surface of bore 902 in sleeve c~m base 900 by grease channels 170 ~Fig. 31).

The drive means ~or the eight-nozzle injection ~olding apparatus incluàes two pairs of sleeve cam bars 35S.
~ach sleeve cam bar 856 (Figs. 93, 93A, 94) has four identical angular slo~s 874 cut through its thickness. Each slot is adapted to receive a sleeve knuckle 868 in it for mounting a sleeve shuttle 86~. The sleave cam bar also has a hole 876 bored through the thickness of its bottom end portion for connecting the bar to other portiGns of the drive means for effecting reciprocating movement of the sleeve cam bar. Each sleeve cam bar 856 also has four identical, narrow, spaced, longitudinal edge slots 878 cut through the width of the bar from its forward edge 880 to its rear edge 882. Each edge slot 878 is positioned to communicate with an angular slot 874. Referring to Figs. 95 and 96, each sleeve shuttle 860, including its internal knuckle 868, is comprised of two mirror image pieces 858 each mountable onto either side of sleeve cam bar 856 when the knuckle portions of each piece are abuttingly joined to each other within angular slot 874 by suitable means, here by the close tolerance slip fit 1~

~L25~ i7 of the oute peripherial surface of the abuttingly joined pieces 858 and the interior surface restriction of axial bore 9Q2 in sleeve cam base 900. (See Fiys. 97, and 99-103).
Alternatively, the pieces may be bolted together. Each knuckle portion is preferably machined to be one piece or integral with its shuttle piece. Each whole knuckle is about .010 inch wider than the width of the sleeve cam bar on which it is mounted to provide a gap between the side walls of the cam bar and the sleeve's inner walls 866. Each sleeve shuttle 860 is slideably mounted onto sleeve cam bar 856 with its knuckle 868 slideably seated within and operatively engaged with a slot 874. The drive means includes suitable axial travel variation compensation means, here including a spring to compensate for any axial play in the drive means or valve means or between them, and for any deviation in dimensions of the involved structures. Therefore, sleeve 800 is mounted onto sleeve shuttle 860 by positioning a helical co~pression spring 8~8 rearwardly into a slip fit within sleeve shuttle annular chamber 873. Spring 888 has an ou~ide diameter of a free length of one inch and a scale rate of 193 pounds per tenth of an inch. ~he free length of the spring is longer than the axial length of chamber 873 and the width of the gap between sleeve shuttled forward face 872 and sleeve rearface 818. The scale rate is the predictable pounds per unit length of one-tenth inch compression~ The spring is pre-loaded with one-hund~ed pounds sprin~
compression when shoulder screws 830 are fully seated in their holes 367. The reason for pre-loading is to compènsate for, i.e., eliminate or alleviate any possible axial play between the sleeve shuttle 860 and sleeve 800. For example, it prevents axial play between the sleeve shuttle and sleeve due to plastic pressure exerted on lip R14 of sleeve 8ao.
The ~huttle moves forward to seat sleeve tapered lip 814 against the matching angular edge 460' of the inside of nozzle caE~ 438 (See Fig. 77A), and, once seated, the shuttle continues to move another thirty-second of an inch further forward while the sleeve remains stationary, to assure seating of the angular interface and a pressure seal to block - ,~7 ~5~5'~

and prevent B material from entering the nozzle gate 596.
The additional thirty-second of an inch movement compresses and is absorbed by the spring 888. The spring had been precompressed to 75 mils and maintaiaed in that condition by the assembly of the shoulder screws in their holes 867.
Thus, when the sleeve is retracted, the shuttle moves one thirty-second of an inch rearward to release tha compression before the sleeve itself moves. This provides leeway should there be any slight deviation in the relative lengthq of the respective sleeves 800 and/or in the dimensions of the components or shells of the nozzle assemblies. Sleeve rear face 818 is moved backward against the bias of the spring and is bolted to sleeve shuttle forward face 872 by shoulder screws a30 in a manner that leaves ~ gap between the sleeve rear face and the shuttle forward face (see Fig. 97)0 This gap allows for the thirty second of an inch additional movement of the sleeve. Shims 831 are employed between shoulder screws 830 and frustoco~ical mounting flange portion 810. The thicknesses of the shims is selected to compensate for dimensional non-uniformities in the valve means and in shuttles and cam bars of the d~ive means. Solid shut-off pi~
834 is mounted to extend through sleeve cam bar edge slot 878, through sleeve shuttle slot 864, knuckle bore 862~
annular chamber 873, spring 888, and finally through bore 820 of sleeve 8000 The height of edge slot 878 permits sleeve cam bar as6 to reciprocate vertically and thereby drive sleeve shuttle 860 to reciprocate axially on the cam bar through bore 902 of sleeve cam base 900 while pin 834 is extending horizontally through each of them.

The manner in which sleeve shuttle 860, pin shuttle 844 and t~eir respective cam bars 856, 350 are assembled within the apparatus will now be described (Figs. 30, 31, 97-105). Each pin cam bar 850 is inserted for vertical ref~iprocation within a pin cam bar slot 890 cut vertically through pin cam base 892 and its ~orward face 893 and through pin cam cover 894 and its rear face 895. In an eight-up multi-polymer nozzle assembly injection molding machine, there are preferably four pin cam bars in two spaced parallel pairs (Figs. 31, 98). Solid pin shuttle 844 is seated for horizontal, reciprocal movement within a horizontal bore 896 cut through both pin cam base 892 and pin cam base cover 894. Each sleeve cam bar 856 is inserted for vertical reciprocation within parallel sleeve cam bar slots 898 cut vertically through the sleeve cam base plate 900. When sleev~ cam bar 856 reciprocates vertically, sleeve shuttle 860, having its knuckle 868 seated within sleeve cam bar slot 874, reciprocates horizontally in a close tolerance fit ~ithin and through sleeve shuttle bore 902 cut horizontally through the entire depth of sleeve cam base plate gO0 and sleeve cam base cover 901. The sleeve cam bar edge slot 878 permits pin 834 to pass through sleeve cam bar 856 as the bar reciprocates vertically. Because sleeve shuttle bore 902 is larger than pin shuttle bore 896, and because sleeve shuttle b~re 902, which extends through the sleeve cam base 90O and ~hrough sleeve cam base cover 901, is longer than sleeve shuttle 860 itself, there is suf~icient clearance to permit horizontal reciprocation of sleeve shuttle 860 through both the sleeve cam base 9OO and the hase cover 901 such that rearward over-travel of the sleeve shuttle is prevented by the portion of the front face of pin cam base cover 894 which surrounds the pin shuttle bore 896. Forward over-travel of the sleeve shuttle is limited by the axial lengths of the cam bar lots.

Any suitable drive means can be employed for independently and simultaneously driving the valve means o~
thi~ invention, here shown as including solid pin 834, and sleeve 800, in accordance with the method of this in~ention.
The drive means for pins 834 include pin mounting means preferably in the form of pin shuttle 844, and the drive means preferably including pin cam bars 850. As shown in Figs. 29, 29C, 30, 31, 99, 100 and 104, the preferred driving means for simultaneously driving pins 834 and pin shuttles 844 also includes servo-controlled pin drive cylinder 906 attached to mounting bracket 908 and having manifold 907 and lS/

5i'7 servo valve 909 (Fig. 100), and the drive cylinder's connecting members includinlg, and by which it is connected through, cylinder piston rod 910, drive frame 912 whose lower horizontal bracket 913 has a pair of spaced, depending ears 914, through bolts 916 passing through the ears, to the two pairs of spaced pin cam bars 850. Each cam bar 850 of each pair is spaced from the other and extends vertically downward through 510ts 890 in pin cam base 892 and its.cover 894.
Prsgrammed, servo-controlled vertical movement of piston rod 910 simultaneously drives each pair of cam bars 850 up and down, and, by means of angled cam guide slots 848, simultaneously drives all shuttles 844, and drives all pins 834 seated therein forward and backward within bores 896 and through tbe apparatus, particularly through all nozzle assemblies 296 in accordance with the methods of this invention.

. Looking now at the bottom of Figs. 29, 29C, 99 and 100, the preferred driving means for simultaneously driving slesves 800 and sleeve cam bars 856, and thei~ mounting means, preferably in the form of sleeve shuttles 860, further - includes servo-controlled sleeve drive cylinder 918 attached to mounting brackets and having a mani~old 919 and servo valve 9~1 (Fig. 100), and the drive cylinder's connecting members including, and by which it is connected through, cylinder piston ro~ extension 920, bracket 922 and through bolts 924, to each sle~ve cam bar 856. .Programmed servo-controlled vertical movement of piston rod 9~0 simultaneously drives each cam bar 856 up and down through cam bar guides, and, by means of angular slots 874 in each cam bar, simultaneously drives all sleeve shuttles 860 forward and backward through their respective bores 902 and simultaneously drives all sleeves connected thereto through the apparatus, particularly through all nozzle assemblies 296 in accordance with the methods of this invention.

In the method of this invention, the operation of the drive means is controlled by the control means, sometimes ~2~ 5~

referred to herein as a control system~ By the control means, the drive cylinders 906 and 918, are programmed to operate in a desired independent yet simultaneous mode which includes simultaneous and non-simultaneous operation of all sleeves relative to all pins. The drive means, along with other features of the inventiQn, independently yet simultaneously provide the same valve means action in each of the eight co-injection nozzles or nozzle assemblies. The terms ~same" or "identical" as used with respect to the inventions contemplated herein, means as much the same as possible given minor insignificant dimensional variations of structures due for example, to machining of parts. ~hus, the terms ~same" or "identical" as used in the description and in the claims includes the meaning i'substantially the same~ or asubstantially identical. n Likewise, the term ~simultaneous 1l as used in the description and claims includes "substantially simultaneously. $his permits the same initiations, ~lows, ~erminations and sequences of polymer flow in each nozzle assembly, consequent simultaneous injection of the same multi-polymer streams having the same, balanced ~haracteristics from all eight nozzle orifices and the forma~ion o~ parisons of the same materials and having the same characteristics in all eight jux~aposed blow mold cavities. In~luded within the control means, are the servo control drive means and programs and the one or more mi~roprocessors with respect to which the drive means are cooperatively associated. The servo control drive means for driving the drive cylinders 906 and 918 are suitably programmed and operated by a microprocessor to operate the eight sleeves and eight pins independently but simultaneously as discussed, and in the desired mode.

The programmed servo controlled vertical movement of the piston rod 9lO for simultaneously driving each pair of pin cam bars 850, as well as the programmed servo controlled vertical movement o piston rod 920 for driving each sleeve cam bar 856 is effected by means of a programmed microprocessor, described in conjunction with the processor 2~;~

control system set forth below. In brief detail, the drive cylinders 906 and 918 are driven by supplying hydraulic fluid to the drive cylinders by means of a servo controlled valve, operating in accordance with pre-programmed instructions iD a microprocessor, described hereinabove as the second processor unit, and described in further detail in conjunction with figures set forth hereinafter. More specifically, and as shown in Fig. 29, drive cylinders 906 and 918 are energized by means of hydraulic fluid flow operated and controlled by means of a servo system which opens and closes the valves permitting fluid flow to enter therein. The position of each of the piston rods of drive cylinders 906 and 918 and their associated cam bars 850 and 856, respectively, are monitored by means of position sensing mechanisms, consisting of a position transducer and a velocity tran~ducer, schematically respectively shown as 918A and 918B in PigO 99, and 906A and 906B in Fig. 104. The precise nature of the movements of the cam bars 850 and 856 requires an accurate means of determining the actual position thereof. As was described hereinabove in conjunction with the ram servo ~echanisms, the system is controlled in accorda w e with the first pre-prosrammed system processor for controlling major machine functions and a second processor pre-programmed to coordinate the movements of the ram servos with the movements of the cam bars. The movement of the cam bars controls the specific sleeve and pin positions for the purpose of allowing polymer melt to enter from the feed channels into the nozzle central channels at the appropriate times for producing the article in accordance with the desired sequence of the present invention. These relative movements, which will be described in further detail below, are pre-established in the second processor or moving the cam bars by driving the hydraulic drive cyl:inders 906 and 918 in accordance with the predetermined pattern. It is specifically important that the pin and s:Leeve movements be correlated and coincide with approprial:e ram pressures, determined by ram servo energization, so that the desired result in accordance with the invent:ion may be achieved. Specifically, the second 5;7 processing unit is programmed to simultaneously coordinate all five rams and the cam bar movements, one with the other, in order to achieve the desired flow characteristics through the nozzle channel as has been described hereinabove. The resultant overall effect of the control system is to provide separate control of each ram pressure and of the pin and sleeve in accordance with the preoetermined temporal profile for controlling the flows of plastic melt materials at the nozzle output in determined amounts and at determined times from the different supplies.

It will be understood that while the no7zle valve means of the present invention have been described in terms of a preferred pin and sleeve embodiment, other, equivalent structures for the valve means and drive means will be appreciated by those skilled in the art after having read the present description. For example, the valve means may comprise a sleeve 620 (illustrated in Fig. 106) axially moveable back and forth in the nozzle central channel and also rotatable therein, as by suitable rack and pinion drive 62~ in which rotation of the pinion or gear wheel 624, attached to or formed as a part of sleeve 620, causes rotation of the sleeve. Rotation of sleeve 620 may also be ef$ected by suitable key-link drive bar structure 626 (Fis.
107). Asial movement of the sleeve selectively blocks and unblocks one or more of the nozzle orifices to selectively prevent or permit 1OW of polymer streams, for example of polymers B, E, C and D, into the nozzle central channel.
Selective rotation movement of the sleeve brings the aperture 804 in the wall of the sleeve out of and into alignment with a nozzle flow passageway, which may be keyhole passageway 443, for a polymer stream, for example of polymer A, to selectively prevent or permit flow of the polymer stream into the nozzle central channel.

Xn another alternative embodiment (not specifically shown), employing khe hollow sleeve of the present invention, the aperture 804 in the wall of tbe sleeve may be selectively ~SS

blocked and unblocked by rotation movement, for example by suitable modification of the rack-pinion or key-link means described above, of the adjacent nozzle shell 430 to prevent or permit flow of polymer into the internal axial flow passageway 803 within the sleeve. Alternatively, a check valve 628 (Fig. 108) may be included within the flo~
passageway 634 for the polymer which flows within the sleeve. The check valve may, or example, comprise a ball 629 urged by one end o a spring 630 against a seat 631 in passageway 8030 The opposite end of spring 630 abuts the end of a hollow inner sleeve 632 which is inserted into friction fit angagement within the sleeve 633. In a further alternative embodiment (Fig. 109), employing the sleeve of the present invention and a modified form 636 of the preferred inner shell 430 tFig. 51), the flow of polymer from channel 637 in shell 636 into the axial passageway 803 within the sleeve is blocked and unbloçked by reciprocal movement of a tapered, spring~loaded sliding valve member 638 housed in a channel 640 formed in shell 636 and which member is biased to the ~losed position by spring 639 and is urgad to its open position by a predetermined increase in prescure of the incoming polymeric material.

Yet another alternative embodiment (Fig. 110~
employs the sleeve of the present invention and a modified form 642 of ~he preferred pin 834 (~ig. 81). Modi~ied pin 642 has its forward end portion 643 formed into a flatted shaft having a semi-circular cross-section. Flow of polymeric material through the aperture 804 in tbe wall of the sleeve 800 into internal flow passageway 803 of the sleeve may be selectively prevented or permitted by selectively blocking or unblocking the aperture 804, by selective rotation of pin 642 within the axial channel 803 of the sleeve, to bring the flatted portion 644 out of, or into, alignment with aperture 804.

In a preferred embodiment, illustrated in Figs.
111-116, the flow of the five polymer streams is selectively _ .~ _ ~2~

controlled by the combination of the sleeve o~ the present invention with means for blocking the sleeve port here shown as a fixed member, such as solid pin 648. It will be understood that the aperture! 650 in the wall of the sleeve is suitably enlarged to permit the hereinafter described flow of polymer streams. It will also be understood that the tip 594 of nozzle cap 438 is modified to enlarge the diameter of a portion 652 of channel 595 to accommodate the thickness of the wall of the sleeve (Fig. 112). Further, in this embodiment fixed pin 648 partially blocks a portion of feed channel 440. In this embodiment, an injection cycle comprises selective movement of the sleeve into six positions or modes to prevent or permit the flow of a selected one or more of polymer streams A through E. In the first position or mode (Fig. 111), ~he sleeve is in its forwardmost position, blocking orifices 462, 482, 502 and 522 to prevent flow of polymers B, E, C and D, respectively, and blocking the exit of inner feed channel 440 in inner shell 430 to prevent the flow of polymer A. In the second mode (Fig.
112), the sleeve is withdrawn sufficiently to bring aperture 650 into communication with feed channel 440 to permit flow of polymer A into the sleeve's internal axial polymer flow passageway 803 which itself is in the nozzle central channel 546~ The orifices remain blocked. In the third mode (Fig.
113), the sleeve is farther withdrawn sufficiently to unblock orifice 462, permitting flow of polymer B into nozzle central channel 546. Polymer ~ continues to flow into passageway 803. The sleeve continues to block orifices 482, 502 and 522, preventing flow of polymers E, C and D. In the fourth mode ~Fig. 114), the sleeve is farther withdrawn to unblock orifices 482, 502 and 522, permitting the flow of polymers E, C and D into nozzle central channel 546. The flow of polymer A continues. In the fifth mode (Fig. llS), the sleeve i9 withdrawn farther, such that pîn 648 blocks the exit of feea channel ~40, preventing flow of polymer Ao Orifices 462, 482, 502 and 522 remain unblocked, permitting continued flow of polymers B, E, C and D. Positioning the sleeve in this mode permits knitting or joining together of polymer C, - Is'7 forming a continuous layer of that polymer in tAe injected article. In the sixth mode (Fig. 116), the sleeve is moved forward to the same position as in the third mode, described above, permitting sufficient flow of polymer B to enable it to knit or join together and ~orm with polymer A a layer which completely encapsulates, among other layers, layer C.
In this mode, polymer A flows from feed channel 440 into passageway 803. The injection cycle is completed by moving the sleeve to its forwardmost position, in the first mode, illustrated in Fig. 111 and desrribed previously. It is to be noted that the size of feed channel 440 and the axial position of the aperture or port in the sleeve wall and of the fixed pin in sleeve 800 can be varied by design to provide a variety of desired opening and closing ~ossibilities and sequences.

I~ another embodiment, employing a solid pin, reciprocal movement of the pin in the nozzle central channel selectively blocks and unblocks inner feed cha~nel 440 in inner shell 430 to prevent or permit flow of a polymer stre3m, for example polymer A. Flow of polymer streams D, C, and B is selectively prevented or permitted by selectively blocking and unbloclcing communication between feed channel exit ports 411, 415, 417 and 418 in feed block 294 (Figs.
41-43), and respectively associated feed channels 442 in inner shell 430 (Figs. 51 and 53A), 444 in third shell 43~
~Figs. 37 and 57A), 446 in second shell 434 (Fig. 63) and 448 in first shell 436 (Fig. 70). Referring to Fig. 117, ~he selective blocking and unblocking of the feed channels, for example illustrative feed channels 654 and 655, may be accomplished by selective rotation of a suitably shaped rotary gate valve member 656 by means, for example, of suitable rack and pinion drive 657. It will be understood that the rear face of valve member 656 is formed to comprise one or more annular shoulders to fit within chamber 380 of the feed block (Figs. 41 and 43) and that the front ace of the valve member 656 contains one or more annular grooves to receive the shoulders of the nozzle shells. It will also be .
/~g - 1~6 -~S6~

understood that valve member 656 contains other, suitablyenlarged slots or channels to permit uninterrupted flow o~
the polymers, whose flow i5 not being controlled by rotation of valve member 656. Alternatively, the selective blocking and unblocking of the feed channels may be accomplished by selective rotation of a nozzle shell such as second shell 434 by means of a suitable rack and pinion drive (shown in phantom in Fig. 117). In this alternative embodiment, it will be understood that the flow channel for polymer A within the inner shell extends sufficiently far in the circumferential direction around the shell so that rotation of the inner shell to block flow of polymer D still maintains the feed channel exit port for polymer A in the feed block in communication with the entry feed channel for polymer A in the inner shell. In both of these embodiments, the means for preventing or permitting flow of the polymer streams through the nozzle central channel are at a distance from that channel and from the no2zle gate, and the degree of control over the start and stop of flow of the polymer streams may not be as precise as that obtained with the preferred embodiment of pin 834 and sleeve 800, described above.

In a further embodiment, illustrated in Fig. 118, the nozzle valve control means comprises sleeve structure having therein two axial polymer flow passageways. The sleeve structure comprises a cylindrical outer sleeve 660 having two apertures in the wall thereof, one aperture 661 being for flow therethrough of polymer D and the other 662 for flow of polymer ~. An inner sleeve 664 has an aperture 665 in the wall thereof for flow of polymer A therethrough.
The outer diameter of the forward portion of the inner sleeve is less than the inner diameter of the outer sleeve to ~orm a polymer flow passageway 666. The outer sleeve is adapted for reciprocal axial movement within the nozzle central channel and the inner sleeve is adapted for reciprocal axial movement within the outer sleeve. The internal flow passageway 666 in the outer sleeve has a sealing land 667 of reduced diameter which cooperates with a ~i6~

portion of the outer surface of the forward portion of the inner sleeve to prevent or permit flow of polymer D into the nozzle central channel. Axial reciprocal movement of the inner sleeve brings the aperture 665 in the wall thereof into and out of communication wil:h the aperture 662 in the wall of the outer sleeve to permit or prevent flow of polymer A
thrcugh the apertures and into the axial channel 668 within the inner sleeve. The flow se~uence is as follows~ The inner sleeve 664 is withdrawn to bring aperture 665 into communication with the aperture 662 in the wall of the outer sleeve 660 to permit flow of polymer A. Next, both sleeves are withdrawn together as a unit to unblock orifice 462 to permit flow of polymer B. These movements of the sleeve may occur sequentially, as just described, to start the flow of polymer A before polymer B, or, if desired, substantially simultaneously, to start the flows of polymers A and B at substantially the same time. Alternatively, the flow sequence may begin by both sleeves being withdrawn together as a unit to permit flow of polymer B, followed by withdrawal o~ the inner sleeve sufficiently to permit flow of polymer A. Both sleeves are then further withdrawn to unblock orifices 482 and 502 to permit flow of polymers E and C, and at the same time the inner sleeve is further withdrawn to bring it out of engagement with sealing land 667 to permit flow of polymer D. Flow of polymer A is stoppad by rotation of the inner sleeve relative to the outer sleeve to bring aperture 66S out of communication with aperture 662. Forward movement of the inner sleeve brings it into engagement with land 667 to prevent flow of polymer D and forward movement of both sleeves in unison bloc~s orifices 502 and 482 and stops flow of polymers C and E. Further forward movement of both sleeves in unison blocks orifice 462 and stops flow of polymer B. This embodiment provides semi-independent control of polymer streams A and D.

~ 'ig. 118A schematically shows a sleeve 8000 adapted to provide an orifice cooperative with the central channel orifices for a flow stream passing axially through the sleeve - ~5'8 -central passageway 8~00 from a source (not shown) exterior o~
the co-injection nozzle. More particularly, Fig. 118A shows co-injection nozzle means ~similar to that shown in Fig. 121, except that the co-injection nozzle embodiment itsel~ herein designated 750 does not have a third passageway or orifice therein and that port 8040 in the wall sleeve is adapted to communicate with a passageway or channel of a feed block or other structure (not snown) exterior o the nozzle, for providing in the preferred method the polymeric material melt flow stream which is to flow through the sleeve central passageway 8200 when pin 834 is sufficiently withdrawn, and to form the inside structural layer A of the article.

Another embodiment of the nozzle means of thi~
invention is that schematically shown in Fig. 118BI which shows a co-injection no2zle embodiment 752 having a central channel generally designated 1546 comprised of a plurality of communicating stepped cylindrical portions, herein designa~ed 760, 762, 764 and 766, having different diameters and formed and defined in part by the respective tips of the frustoconical portions of nozzle shells 1430, 1~32, 1434, and 1436. Sleeve 8000' is mounted in a close tolerance slip fit within the central channel combining area. The sleevels outer wall has stepped cylindrical portions 761, 763, 765 and 767 respectively joined by interstitial tapered annular walls which abut the passageway outer walls OW of shells 1432, 1434 and 1436 and which cooperate with the stepped cylindrical walls to block the orifices of passageways 480, 500 and 520.
The tapered lip 1814 of sleeve 1834 does not abut the outer wall of t:he first passageway 460. That passageway is shown blocked by the wall of sleeve 8000' Pin 1834 is mounted in a close t:olerance slip fit and is axially moveable within sleeve central passageway 1820. The nose of pin 1834 has an annular t:apered wall 1837 which communicates with the radially outermost wall of the pin and which is adapted to abut port:ion 601' of nozzle cap outer wall O~ which fo;ms first passageway 460. Tapered wall 1837 communicates with a cylindrical protruding nose 1835 whose wall is adapted to 1~/
- ~L~9--slip-tolerance fit within channel 595 in nozzle cap 1438.
The embodiment shown in Fig. 118B is meant tv represent and to include within the scope of this invention, those valve means structures adapted to block to stop and unblock to start the flow of the E, C and D layer materials substantially simultaneously relative to one another.

Fig. 118C schematically shows an enlarged portion of a co-injection nozzle embodiment 754 having internal passageways 1480, 1500 and 1520 and their respective orifices 1482, 1502 and 1522 radially further removed from the central channel and in communication with a main or second passageway 1501 having its main orifice 1503 in communication with the nozzle central channel 546. Orifice 1503 in this embodiment is sometimes referred to, and can be considered as the internal or second orifice. The polymer material melt flow streams which flow from orifices 1482, 1502 and 1522 can com~ine in main passageway 1501 and flow from o~i~ice 1503 as a combined stream into the central channel. This orifice arrangement can therefore provide the three internal layer ma~erials, that is, internal layer C flanked by intermediate layer materials E and D, as one internal layer or stream or forming a three material internal layer for the articles of this invention In other embodiments (not shown), the tips of nozzle shells 434' and 432' can be of different radial distances from the axis of the nozzle central channel, and only one of them can be radially removed from the central channel. Preferably, the axial distance from the leading lip of the main orifice to the trailing lip of that orifice is from about 100 to about 900 mils, more preferably from about 100 to about 300 mils.

A particular advantage provided by the valve means of this invention relates to the physical arrangement of the orifices. Their very close proximity to each other coupled with the capability of the valve means of very rapidly blocking and unblocking all of the orifices, is highly advantagevus because it provides to the process the ability - ~0 -~:5~

to effect very rapid changes in pressure at the orifices.
This, coupled with pressurization, provides to the process the capability of effecting highly desirable rapid onset flows of a material into the central channel. Rapid unblocking and blocking is particularly important with respect to the internal orifices of a five or more layer process with respect to which it would be highly desirable that the initiation of flow of the E, C and D layer materials be effected at the same time, and that the termination oi their flows also be effected at the same time. Given the staggered physical arrangement of their orifices in embodiments wherein they individually communicate with the nozzle central channel, the high rapidity of movement of the valve means in positively unblocking and blocking these orifices with pressurization minimizes the e~fects the arrangement has on opening one orifi e before another. The valve means of this invention utilized in a co-injection nozzle having at least first and second orifices, can unblock all of the orifices within a period of about 75 centisecond~, desirably within about 20 centiseconds, and preferably within about 15 centiseconds. With respect to such a co-injection nozzle wherein the first oriice has its center line within about 350 mils of the gate, the second orifice has its center line within about ~50 mils of the center line of the first orifice, and the leading lip of the first orifice and the trailing lip of the second orifice is no greater than about 300 mils apart, the valve means of this invention are adapted to move to a position which blocks all orifices and to a position which unblocks all orifices within about 75 centiseconds. With respect to a nozzle embodiment which has at least three fixed orifices, two of them being close to the gate, the first be~ng proximate the gate, the second being adjacent the first orifice, and the third orifice being remote from the gate, wherein each of the first and second orifices are narrow and annular, combining area of the central channel has an axial length of from about 100 to about 900 mils, and the leading lip of the first orifice is within about 100 to about 900 mils of the gate, the valve -~ ~ 5Ib2 5 7 means of this invention can unblock all orifices within flO~
about 15 to about 300 centic,econds, preferably within from about 15 to about 75 centiseconds. Such rapid unblocking of all orifices can also be effected with respect to a nozzle having at least three orifices wherein the combining area has an axial length of from about 100 to about 900 mils, the leading lip of the first orifice is within about 100 to about 900 mils of the gate, and the center lines of each of the first and second orifices lie substantially perpendicular to the axis of the central channel. With respect to such a co-injection nozzle, the valve means can be utilized such that the elapsed time between the allowing of all materials to flow through the orifices and the subsequent preventing of the flow of all materials from their orifices is from about 60 to about 700 centiseconds, preferably from about 60 to about 250 centiseconds. Further in relation to such co~injection nozzles, and with respect to preventing the flow of polymer material through the second orifice while allowing flow of structural material through the first, the third or both the first and the third orifices, and then for allowing flow of polymer material through the second orifice while allowing material to flow through the third orifice, the valve means of this invention are adapted to effect both of said steps within a~out 250 centiseconds, preferably in about 100 centisecondsr The valve means of this invention are physical means for positively physically blocking, partially blocking or unblocking and thereby controlling the flow of polymer melt stream material from co-injection nozzle orifices into the nozzle's central channel. This capability provided by the valve means obtains many advantages, some of which will now be describled. The positive control provided by the physical valve means avoids problems that occur without valve means, such as having to synchronize the pressure of all streams or layers at all points in the injection cycle in order to avoid problems of cross-channel flow or back flow from the central channel into one or more of the orifices, or from one orifice L~ Y

, ~L2~ 7 into another. It also avoids the problem of premature flow through an orifice of any or all of the respective layers.
For example, as can be more easily understood in connection with Figs. 118D and 118E, when the A and B layer materials are flowing in the central channel of a co-injection nozzle, they create a pressure in the central channel, referred herein to as the ambient pressure. The pressure, for example, of internal layer C material at the orifice, absent physical valve means, has to be very carefully controlled to be just equal to or slightly below the pressure of the flowing A and B materials. If the pressure of the C layer material is greater than that of the A and B layer materials, the C layer material will prematurely flow into the channel.
~f the pressure is too low relative to the pressure of ~he A
and B materials, either or both of the A and B layer materials will back flow into the C orifice. It may be possible to compensate for the back flow of A and/or B
material ints the C passageway by altering the timing of when the C passageway pressure level is high enough to start flow, that is, by increasing the pressure exerted on the C material earlier than it would be exerted if there were no back flow, to force the A and/or B materials back out of the C orifice, and such that C will enter the central channel at the same time as it would have without the back flow.

Another advantage of the positive control provided by the physical valve means of this invention, is that the valve means physically block the orifices and thereby allow for substantially high prepressurization levels to be obtained prior to injection of one or more of the materials into the central channel, substantially higher levels than would be possible without the valve means. Despite the high prepressurization, physical blocking of the orifices prevents premature flow and back flow. Without valve means, reliance must be placed on the very sensitive and critical control and synchronization of the pressure balancing of the respective materials. The ability ~o prepressurize one or more of the respective flows with valve means in turn provides additional / ~, 5 ~ lf~3 -~6~

advantages. For example, as will be explained, prepressurization is essential for obtaining simultaneous and/or uniform, rapid onset or initial flow over all points of an orifice into the central channel and for obtaining a uniform leading edge about the annular flow stream of a materialO As will be explained, this is particularly important wi~h respect to the internal layer C material.
Another of the many advantages of prepressurization is that given the no zle design of this invention which provides a primary melt pool of polymer melt material aajacent each orifice, prepressurization overcomes non-uniformities in design or in machine tolerance variations oi the nozzles, the runner system, and the flow directing or balancing means, e.g., the chokes. It also helps overcome temperature non-uniformities of the runner system including the nozzle passageways. Without physical valve means for blocking the orifices, the pro~ess is limited to the aforementioned synchronized, sensitive, lower levels of prep~essurization and there would be diferences in the pressure levels obtained at the corresponding respective orifice in each of the plurality of co-injection nozzles of a multi-coinjection nozzle injection blow molding machine. Even with the nozzle ~esign of this invention which provides a primary melt pool adjacent to the orifices, if the polymer melt material in each primary melt pool is not pressurized, it would not provide a rapid onset flow once the orifice is unblocked.
Additionally, prepressurization assures that the primary melt pool at each corresponding orifice in each of the respective nozzles will have the same level of pressure prior to initiation of flow; therefore, the injected articles, for example the parisons ~ould, with prepressurization and valve means, tend to be more uniform at each injection cavity than without valve means and/or without higher prepressurization levels.

Still another advantage provided by the physical valve means of this invention is that in providing the capability of physically blocking and unblocking the G
- 1t~4 -~L~S~i2~7 respective orifices, there is provided an improved capability of starting and stopping the respective flows in the sequence required to permit the formation of articles of very high quality wherein the internal layer is continuous and substantially completely encapsulated. More particularly, the physical valve means are adapted to block physically and to stop cleanly the flow of the layer A polymer flow stream material while the C layer material is flowing. This permits the layer C material to come togetber and knit in the central channel of the nozzle and be continuous at the sprue of the injected article.

Other advantages provided by the valve means of this invention, especially by the preferred sleeve and axially reciprocable pin embodiment, are that they can be employed to assist in knitting the internal layer (or layers) with itself in the central channel, and/or in encapsulating said layer (or layers) with either or both of the outer B and/or inner A
structural 07 surface layer materials. Preferably, the valve m~ans are used to, in the same operation, assist in both knitting and encapsulating the internal C layer material(s).
With respect to knitting, for simplicity, reference will be made to only the internal layer material. To knit it, preferably, the moveable pin blocks the orifice of the A
layer material and then the pin moves the A material aheaâ of it into the central channel while the B and C layer materlals are flowing. When the pin stops short of the sleeve lip, the C layer material knits. Then the valve means blocks the flow of the C layer material while the ~ layer material is flowing. To encapsulate, the knit by one method, the sleeve and pin, while flush, are moved forward advancing the knit toward the gate while the B layer material covers it.
Finally, the B layer material encapsulates the knit as the knit is pushed through the gate. The preferred method of knitting and encapsulating is to move the sleeve and pin forward with the pin inset upstream within the sleeve, as will be explained with reference to Fig. 77A. That Figure shows the conical nose or tip 836 of pin 834 axiall~ inset ~ 2S6~

upstream within sleeve 800 in the central channel of a co-injection nozzle to provide an area within the sleeve forward end for accumulation of polymer material therein.
Prior to or while moving the valve means axially forward through the nozzle combining area towards the gate, polymeric material for example for forming the inside surface layer A
from third annular orifice 440, can be accumulated or maintained in the forward inset area in fron~ of the pin tip and within the sleeve, which material can be used to assist in encapsulating the internal layer C material in the combining area of the central channel. Preferably, the pin is moved forward relative to the sleeve to eject mo t of the material in front of it and thereby enhance the encapsulation of the internal layer. The pin can be inset as desired although if it is inset too little, the knit will be acceptable but there may be an insufficient amount of retained material to completely encapsulate the layer~ This ~ay of course be acceptable for certain container applications. Insetting the pin too far may result in a thin knit of the C layer material. The assistance of the valve means and the inset method is most e~fective when A layer material is accumulated and used for encapsulating, particularly when the A and B layer materials are the s~me, or when they ~are interchangeable or compatible.

The valve means can also be used advantageously in combination to flush, clear or purge polymer material from the combining area or from whatever portion or extent of the central channel desired. When the sleeve has moved fully forward through the central channel of the preferred nozzle assembly of this invention, its tapered lip 814 abuts against a matchiny surface portion 460' of the leading wall of the first passageway 460 (See Fig. 121), and if desired, the pin may be moved further forward into channel 595 of nozzle cap 438 to cLear that remaining area of the central channel of polymeric Daterial, say, before or at the termination of an injection cycle.

l~8 .~

ii7 An important benefit provided by th~ physical valve means of this invention is for repetitively precisely timing the starting, flowing and stopping of the respective flow streams for each cycle. This in turn provides for uniformly consistent characteristics in the articles formed in each cavity, each cycle. The valve means of this invention are also adapted to block the flow of the respective materials in a sequence which is not the reverse of the unblocking sequence.

It will be understood that the valve means o~ this invention, especially the preferred dual valve means comprised of the sleeve and moveable shut-off pin, are adapted to and can be modified and utilized to block and unblock some or all of a plurality of co-injection nozzle orifices in a variety of combinations and sequences as desired.

Still another advantage provided by the physical valve means of this invention is that rapid cycle times are obtained, even for lony runner systems. A "long runner systema here means one channel or runner, or a plurality of communicating channels or runner-~ through which a polymeric melt material flows to a nozzle and which extend(s3 upstream about 15 inches or more from the axis of the nozzle central channel ~See Figs. 118~ and 118G~. As mentioned, the valve means allow for rapid and high levels o~ prepressurization This shortens the time recIuired to build up the necessary pres ure for initiation of the flow of C, it provides a rapid onset flow and it shortens the actual injection cycle time, as compared to cycle times without valve means and prepressuri2ation. The physical, positive blockage of the respective orifices provides for rapid anà precise termination of flow at the end of each injection cycle, prevents leakage or drooling into the channel, and avoids long cycle time delays due to lengthy pressure decays for the termination of flow.

In a long runner multi-cavity injection molding machine without valve mean~;, the long response time and delay of pressure in the eye of t:he nozzle would make it difficult to knit or encapsulate the C material in the combining area of the central channel without cross flow of one material into the orifice of another material.

Particular reference will now be made to Figs. 118D
and 118E which show, for a multi-cavity injection molding machine having a long runner system, a comparison of pressure versus time, in the combining area of co-injection nozzles, with and without valve means operative in the combining area. More particularly, Fig. 118D shows that without valve means there is zero pressure in the nozzle prior to the start of the flow of any of the polymeric materials, and that upon initiation of injection of the A and B layer materials into the central channel due to ram displacement, the ambient pressure due to flow of the A and B materials into the ~entral channel is represented by the curve having short lines of equal length. The pressure and ~low of the internal layer material C with or without other internal layers is represented by the curve having long and short dashed lines.
It represents a build-up of pressure of C which must be synchronized to the ambient pressure development of the A and B materials but which is at a slightly lesser pressure such that C does not flow into the central channel. At a certain desired point of time represented by the X on the time abscissa, the pressure of the C material is increased such that at a pressure level indicated as Pl, all pressu~es are equal, and just after that point in time, the C material flows into the central channel while the A and B materials are there flowing. This is represented by the solid line curve in the upper portion of the Figure.

With valve means, prior to opening any orifices, therè is a residual pressure in each of the passageways. In Fig. 118E, this pressuse is arbitrarily selected to be represented as PL for the A and B layer materials. At time 2~i'7 zero, there is no melt in t:he central channel (the valve means is there blocking the orifices) and thus the ambient pressure is zero. As soon as the valve means opens an orifice (A and/or B), ambient pressure rapidly develops to the level of PL. Due to flow restrictions as the in~ection cavity is filled, the ambie!nt pressure must gradually increase by appropriate ram displacements in order to maintain the flow of A and B.
In the meantime, the internal orifice (here for simplicity, the orifice for the C layer material) is physically blocked with the valve means, the pressure of the C material in the passageway at that orifice (shown as long and short d shed lines) is maintained at (or increased to) the level indicated by P2 in the drawing. At the time represented by point X on the abscissa, the valve means allows C material to start to flow into the central channel combining area. Thereafter, all~of the materials A, B and C ~low into the central cha~nel and th~ ambient pressure rises accordingly as indicated by the solid line. A comparison o~ Fiys. 118D and 118E shows that the valv~ means operative in the nozzle central channel permits the materials in the passageways to be prepressurized, the level oI prepressurization can be significantly high, pressurization is easily controlled, (back flow of polymer material, either from the central channel or another orifice into the orifice of a different material is prevented) and the allowance of pressure build up with the valve means, regardless of runner length, eliminates having to closely synchronize the relative pressures of the internal layers with the ambient pressure of the A and B
materials flowing in the central channel. A comparison of the Figures also shows that due to the prepressurization of the A, B and C materials, the flow rate of the three materials in Fig. 118E is greater than the flow rate of those materials in Fig. 118D.

Figs. 118F and 118G are comparisons of cycle times of multi-cavity injection molding machines having long runner ~ystems, ~with and without valve means. In Fig. 118F

/~1 _ ~9 _ 2~7 (co-injection nozzles without valve means), after the ena of injection there is very gradual decay of pressure of say about 40 to 50 seconds for a long runner system. This gradual decay delays the start of the next cycleO Without a positive means for blocking the respective orifices, such a long delay is necessary to avoid undesired flow of material from the orifices into the central channel prior to the next injection cycle. This is to be compared with Fig. 118G
wherein the same multi-cavity injection molding machine dith the same long runner system and co-injection nozzles having operative therein valve means wherein at the end of injection, the respective orifices are immediately and very rapidly blocked to prevent flow of material into the central channel. The positive blockage of the respective orifices permits rapid replenishment of material into the passageways and rapid initia~ion of repressuri2ation of the system ~o re~dy it for the next cycle. Thus, with valve means the time delay between cycles is greatly reduced. Also the overall length of the injection cycle is greatly reduced.

The valve means of this invention are, however, not without limitations. First, there is a limit on the amount of pressure that can be imparted to the blocked material in the nozzle passageway. While this is not a problem at the pressure levels utilized in accordance with this invention, beyond the limit, polymer melt flow material wo~ld tend to leak from the orifice into the central channel and might back flow into another orifice. A second limitation is that given the nozzle design wherein the pascageways are provided in a certain axial order, the valve means, when combined with high levels of prepressurization, limit the process to a sequence dictated mostly by the design, for example, to opening say the internal orifices for the E, C, and D layer materials in that order, that is, E before C and C before D, and to blocking the orifices in the reverse order. Given the physical locations of and distances between the respective orifices, upon opening of the orifices, the E material will enter the central channel before G, and C before D.

r~4 ~ O ~

~25~

Therefore the leading edge of the annular stream of E layer material might tend to slightly axially precede the leading edge of that of the C layer material and likewise the leading edge of the C layer material might tend to slightly axially precede that of the ~ layer material. With this sequential pattern of initiation of flow into the central channel, in certain circumstances, there may tend to be delamination in the resulting injection molded article between the C layer and the inner structural material layer or less than desired side wall rigidity, should there be no or an inadequate amount of D adhesive adjacent to and interior of the leadin~
edge of the C layer material. This might arise due to the axially offset upstream location of the D layer material leading edge relative to the C layer material leading edge.
~owever, it has been found that in accordance with the methods of this invention, this tendency can be overcome by initiating positive displacement of and prepressurizing the E
l~yer material in its passageway while its orifice is blocked with the valve means. The prepressurization is to a level which creates an abundance of E material at its blocked osifice, which abundance, upon removal of the blockage, initially flows into the central channel in a manner that the leading edge of the C layer stream flows into and through the abundance of E layer material, and such that the E layer material flows radially inward toward the axis of the cen~ral channel about the leading edge of and to the interior of the C layer material, and joins with the leading edye of the D
adhesive ~aterial. This fully encapsulates the leading edge of the C layeE material flow stream with intermediate adherent layer material and thereby prevents delamination between the C and A layer materials. It should be noted that without valve means, there is no such sequential limitation dictated by nozzle design. The D layer material flow can be initiated prior to initiation of the C layer ma'erial flow and prior to E layer material ~low, or all flows can be initiated simultaneously since the means for moving the polymer ~aterial, e.g., the rams can be utilized to independently initiate flow of the respective flow streams.
1~?~

Thus without valve means there is no limitation on the sequence of opening and closing of the internal orifices.
~owever, it is felt that thle advantages of using valve means by far outweigh the aforementioned limitation and therefore preferred embodiments of this invention employ the valve means of this invention.

The Pressure Contact Seal In injection molding machines, it is imperative that during their operation at on-line temperatures, there be an effective pressure contact seal bekween each sprue orifice and each juxtaposed nozzle orifice, particularly between each injection cavity spxue orifice and juxtaposed injection nozzle orifice. 7Effective" herein means that during operation, all of the respective juxtaposed orifices are aligned axial center line to axial center line, and there is a constant, uniform, ~ull~ non-leaking pressure contact seal betwe~n and about the faces of the juxtaposed sprues and nozzles. "Effectiven herein also means operative and that each, any, or all of the aforementioned requirements of alignment, constancy, fullness, non-leakage and uniformity need not be ab.~olutely present but can be substantially present. Misalignment or an improper pressure seal contact sauses leakage, loss of pressure, and often improperly formed plastic articles.

In the case of conventional single or unit cavity injection molding machines, obtaining and maintaining an effective pressure contact seal between one injection nozzle orifice with one sprue cavity orifice is not a significant problemO In such machines, the fixed platen is located between the moveable platen and the injection nozzle. The tool set and the injection cavity are comprised of two matching portions, each attached to a juxtaposed face of the moveable and fixed platens. The injection nozzle is moved leftward in~o the cavity sprue in the right side of the fixed platen and it is sealed thereagainst by hydraulic pressure.

~7~

~2~q6~

Alignment of the cavity sprue orifice and nozzle orifice is not a problem because each is mounted on the axial center line of the machine and because the cavity sprue is a female pocket and the nozzle is a matching male configuration, such as a ball nozzle. Alignment and a pressure contact seal is obtained because the injection nozzle is mounted onto the front face of the extruder which does not deflect and which is hydraulically driven to maintain the pressure contact seal.

~ owever, with respect to multi-cavity, multi-nozzle injection molding machines, obtainin~ and maintaining proper alignment and a constant, uniform pressure contact seal between all nozzles and sprues has heretofore been attempted to be obtained by thermal expansion of its structure. This has been a significant problem. In one such machine, thermal expansion of the runner was relied on to obtain and maintain an effective pressure contact seal between the multiple injection nozzles and cavity sprues. This meant the machine had to be at high operating temperatures and tended excessively to force and compress the injestion nozzles against the cavity sprues with the result that at lower temperatures, there was a gap between the juxtaposed nozzles and sprues caused either by insufficient thermal expansion or by excess metal compression. The resulting gap phenomenon causes polymer leakage and greatly limits to a narrow range the temperatures at which the machines can effectively operate without nozzle leakage or breakage. For one such machine, the operating temperature range was about 450F. to about 455F. These factors thereby limit the polymer materiale; utilizable to those which can be employed within the narrow temperature range. Also, in some conventional multi-no~:zle injection machines, the runner is attached to the fixecl platen by bolts which often break due to a temperature differential between the runner and the bolts, such as when the former is at a higher temperature and thermally expands faster than ~he bolts. Further, in multi-cavity, multi-nozzle, single-polymer injection I ~ ~
-- ,1~3 --~i6~i7 machines, the forward injection pressure of polymers from the multitude of injection nozz:Les during injection and purging cycles, creates a great amount of back pressure which forces the runner and injection nozzles backward and thereby creates a gap or separation and lealcage at the injection nozzle cavity sprue interfaces.

This invention does not rely on thermal expansion to obtain and maintain an effective pressure contact seal. This invention overcomes the previously mentioned problems, and provides and maintains through a virtually open range of on-line operating temperatures of at least from about 200F.
to 600F. and higher, an effective pressure contact seal between all nozzles and sprues, particularly all eight juxtaposed injection nozzle sprues or orifices and injection mold cavity sprue orifices.

Alignment of No~zles and Cavity Sprues Alignment of parts is obtained and maintained by the followin~, interrelated operating conditions and portions of the structure of the machine. These structural elements and conditions cooperate to achieve and maintain alignment of the iniection nozzle and cavity sprue orifices. Initially, there will be described the structures and conditions which relate to the runner block and its components. First, the runner block and all of the components mounted therein are maintained at substantially the same operating temperature.
Therefore, all of these structures and components expand and contract t:ogether. This permits the apparatus to obtain and maintain on-stream alignment of the center lines of, and the matched seating of, the injection nozzle and cavity sprue orifices, the manifold extension nozzle and runner extension sprue orifices, and the polymer flow channels. Second, because runner block 288 is supported at its center at one end by its pilot pin 951, supported by and through the injection cavity bolster plate, C-standoff, adjusting screws and tie bar, and at the other end by the oil retainer sleeve ~S~7 flange which is supported by and through the ~ixed platen, and because it has a rectangular shape (Figs. 29, 29A), when the runner block is heated~ its center line moves upward to a precisely predictable desired point. Third, as shown in Fig.
29A, the runner block and :its components can be moved upwardly to a precise desir.ed hold dimension set position for operation by means of front and rear pairs adjusting screws 117, each screw of each pair being horizsntally aligned with and parallel to the other of the pair, one screw of each pair being on each side of the runner block. The adjusting screws are threaded through C-standoff horizontal members 128 and bear upon non-moving tie bars 116 which pass through moveable platen 114 and are fixed at their forward ends to a rigid housing which houses the drive means 119, and at their rearward ends to fixed platen 282 (Figs. 11, 12). The pair of adjusting screws at the forward end of the machine is located close to blow mold bolster plate 106 and the rearward pair is positioned just forward of the fixed platen. Since the blow mold bolster plate is bolted by socket head cap bolts 130 to ~ixed platen 282 through the vertical members 124 and horizontal members 128 of C-standoffs 122, turning the adjusting screws in one direction raises the C-standoffs, and, through the tying together of the respective structures, raises the blow mold bolster plate, injection cavity bolster plate 950, the runner block and the nozzle assemblies mounted therein. Once the adjusting screws are in the hold dimension cet position for operation, all twenty-two bolts 130 which are tied to the fixed platen are tightened to a locked position. This locks the entire runner block and the runner extension in a fixed centered position~ Upon heating to the desired operational temperature, the rectangular shaped runner block and the runner extension can float radially out from its center during thermal expans.ion to a predicted, desired hold dimension set position relative to the center point of the moveable platen whereat the injection noz~le and cavity sprue orifices and all flow channels in the various structures are operationally aligned along their axial center lines.

There will now be described a second group of structures which cooperate to provide alignment of the injection nozzle and cavity sprue orifices. ~erein are two nozzle assembly-related design features. The first is that the tlps of nozzle caps 43~ have flat faces 439 which match flat faces on each injection cavity sprue. This provides a flat sliding interface between the respective structures to allow for thermal expansion of the runner and movement of the nozzles and nozzle caps mounted therein without fracturing one or more of the nozzles, sprues or other structures.
Conventional round-nosed nozzles and matched concave sprue pockets do not permit such sliaing interfacial actions without often breaking or damaging a sprue or nozzle tip or some other structure. The second is that the diameter of the central channel 595 at the orifice of the gate 596 of the injection nozzle is smaller than that of the sprue orifice, whereby the perimeter of the orifice of each channel 595 at the gate will still be encompassed within the diameter of each sprue opening even when there might be a slight misalignment of the axes of channels 595 and juxtaposed sprues, due, for example, to variations of nozzle-sprue dimensional specifications, variations in the operating temperatures of the nozzles or of the runner block at differ2nt process conditions, and changes in temperatures required by the injection of different sets of polymers. In the preferred apparatus, the diameter of the orifice of channel 595 in the tip of the nozzle is 0.156 inch and the diameter of the sprue is 0.187 inch. One added advantage which arises from the different diameters is that it promotes breakage of the polymer melt in or at the area of the interface of the nozzle cap and cavity sprue.

~ Floatation of the Runner Means There will now be described a third group of structures and opera'ing conditions which cooperate to obtain and maintain center line alignment o sprue and nozzle ori~ices. According to thi~ aspect of the invention, the - ~6 -t~

runner means which includes a runner or runner block 288, and runner extension 276 are mounted on, and are ~ree to float axially on the absolute center line of the apparatus. They are mounted by mounting means in a minimum contact, gap-surrounding, free-floating manner which allows them thermally to expand and contract axially and radially from the center line, while maintaining the center line mounting and alignment. In particular, as shown in Figs. 14, 17, 30, 31, 119 and 120, the runner means, including runner block 288 and 211 of its attached components, including runner extension 276, whose front face i5 bolted to the runner block by bolts (not shown) which thread into bolt holes 953 in the front face 952 of the runner extension, are freely supported at the forward end of the apparatus by means of pilot pin 951 which is ~ounted on the axial center line of the runner extension, is totally encapsulated in cut out 970 in the runner extension's forwara face, and runs through the front portion of and has its axial center line on and along the axial center line of runner block 288. Pilot pin 951 is anchored and, therefore, not free to move axially relative to the runner assembly. It protrudes forward through a plain bore 945 in the runner block and through a matched diameter axial supporting bore 956 in injection cavity bolster plate 950. Pilot pin 951 rests on or is mounted on and the weight it carries is borne by the lower a~cu~te wall portion of the injection cavity bolster plate bore 956. The weight of the runner block and its attached components not borne by the pilot pin and the wall of bore 95~ is ultimately borne by fixed platen 282. Ribbed middle portion 279 of the runner extension ~see Figs. 30, 31) is tolerance-fit mounted within a cylindrical oil retainer sleeve 972 which is boltea by bolts 980 to the runner extension through the sleeve's radially inwardly directed flange 974. The sleeve has a main bore defined by a cylindrical wall whose internal surface g75, in cooperation with runner extension annular fins 281, form the outer boundaries of annular oil flow channels 277, and a sec:ondary bore formed by annular surface 978, whose internal diameter is controlled to contact the outer ~urface ~2~i6257 of the runner extension rear end portion 278. The flange's outer surface 980 is piloted to fit within and contact the wall which Qefines an axial supporting bore or first bore 982 in fixed platen 282. The rear portion 278 of the runner extension extends through fixed platen second bore 984. As seen in Fig. 31, since the only contact between the oil retainer sleeve and any other structure is that between its outer flange and the fixed platen first bore, the weight o~
the runner means, including the runner block and its components, including the rear portion of the runner extension, which is not borne by pllot pin 951, is borne at that place of contact by the fixed platen. Thus, the entire weight of runner block 288 and all components mounted therein, such as T-splitters 290, Y-splitters 292, feed blocks 294, nozzle assemblies 296, and runner extension 276, is supported b~ pilot pin 951 ~nd oil retainer sleeve flange 974 and is respectively borne by injection cavity bolster plate 950 and fixed platen 282. The runner means or entire runner block 288 and runner extension 276 are free to float axially as a unit due to thermal expansion or contraction, because of the sliding tolerances between the inside diameter of bore 956 in the injection cavity bolster plate and the outside diameter of the pilot pin, and between oil retainer sleeve flange 974 and the wall of fixed platen first bora 982, and because of the clearance or gap, generally designated G, which surrounds t~e runner block and its components, including the runner extension. ~he gaps occur between runner extension rear portion 278 and fixed platen second bore 984, between the forward face of the fixed platen and the rear face of oil retainer sleeve flange 974, between the oil retainer sleeve outer diameter and the common bore 986 running through nozzle shut-off assembly 899 which is comprised of sleeve cam base cover 9Gl, sleeve cam base 900, pin cam base cover 894, and pin cam base 892, between the rear faces of the runner block and of components attached ~o the runner block~ such as annular retainer nut 824, and sleeve cam base cover 901, between the outer sides of runner block 288 and the surrounding structure such as pos~s 904 and -- ~d --~:5~i~5~

962, and between runner block forward face 289 and the rear face of injection cavity bolster plate 950. This minimum contact, gap-surrounding arrangement provides a virtually free-floating sy~tem which allows the runner block and its components, including the runner extenslon, to maintain their axial center line mounting while they expand and contract radially and axially, and float virtually freely axially due to changes in operating temperatures. By minimizing contact between the runner block and its components with adjacent or surrounding structure, which are at lower temperatures, the arrangement minimizes heat 105s to those structures and helps to obtain and maintain substantial temperature uniformity throughout the runner means, particularly in the runner block and with respect to the plurality of nozzles mounted therein.

Additional structure according to the present invention cooperates with the previously-described structure to assis~ in providing a total system which establishes and maintains the unique, constant! uniform, ~ull and non-leaking aspects o~ the effective pressure contact seal between each of the manifold extension nozzles and runner extension female pockets, and particularly at and about the interface between each of the eight injection nozzles and their }uxtaposed cavity sprues.

The total system includes structures which in combination absorb or compensate for the total rearward pressure exerted by the clamping force of moveable platen 114, the injection no~zle-cavity sprue separation pressure (also referred to as injection back pressure) caused by the forward injection of polymers under pressure through the eight injection nozzles, and any force due to axial thermal expansion of the runner block and its components, including the runner extension.

The Ri~dized Structure A main feature of the total system is the support /~'1 ~z~

means or ~rigidized structuren of the apparatus of the invention. It includes a frame-like structure comprised of second support means including a member or injection cavity bolster plate 950, three standoff systems, a nozzle shut-off assembly, and the first fixed support means, or fixed platen. The co~ponents of the rigidized structure are load-bearing members which ]protect the structure of the apparatus located between moveable platen 114 and fixed platen ~82, by themselves bearing, instead of the runner block and its components bearing, the great compressive clamping force, usually between 45 to 500 tons pressure, exerted in the rearward direction by hydraulic cylinder 120 on the moveable platen when the latter is in its closed position. (See Fig. 11). The rigidized structure uniformly supports and distributes the compressive forces about the injection cavity bolster plate 950, prevents it from breaking, minimizes its deflection and prevents damage to and excessive compression forces from being exerted on the injection nozzles. In doing the above, the rigidized structure ~aintains the injection cavity bolster plate in a substantially vertical plane and thereby maintains the ~aces o~ the injection cavity sprues in a substantially vertical piane. This permits the faces or sprue faces of the nozzle caps, held in a substantially vertical plane by ~he rigid mass of the runner block, to contact and seat fully, completely, an~ uniformly against the juxtaposed injection cavity sprue faces.

As shown in Figs. 29, 29A, 30, 31, and 98, ~here are three standoff systems in the apparatus of this invention.
The first system includes a set of ten large standoffs, each designatecl 962, and a set of eight small standoffs, each designatecl 963. Each large standoff is positioned on a bolt 960 and each small standoff is positioned on a bolt 961.
Standoffs 962, 963 and bolts 960, 961 run through the runner block, the! for~er extending between the rear face of injection cavity bolster plate 950 and the forward face of sleeve ca~l base cover 901, and the latter extending through ~, ~ .~

~L25~ 5~

the injection cavity bolster plate 950 and being threadedly fasten~d to cover 901. The main purpose of these standoffs is to maintain the cavity sprues in a vertical plane and to minimi2e variation in cavity deflection due to the clamping force. Due to their proximity to the injection nozzles, they also assist in preventing the nozzles from being damaged or crushed by the clamping force.

The second standoff system includes a set o~ eight posts, each designated 904t which are outside of the runner block and run from the rear face of injection cavity bolster plate 950 to the forward face of sleeve cam base 900 where bolts 905, which run through the posts, screw into threaded holes in sleeve cam base 900.

The third standoff system is comprised of two C-shaped standoffs, each generally designated 122, one positioned on each side of runner block 288. Each one abuts the rear face of blow mold bolster pLate 10~ and extends to and abuts agai~st the forward face of fixed platen 282~ Each C-standoff ha~ three components, a vertical member 124, and upper and lower horizontal members respectively designated 126, 12~. Bolts 130 for securing the C-standoffs between blow mold bolster plate 106 and fixed platen 28~, pass through the blow mold bolster plate from its forward face, extend through the C-standoffs and are threadedly secured to the fixed platen. The three standoff systems in concert ahsorb the clamping force and uniformly support and prevent or minimize non-uniform deflection of the injection cavity bolster plate.

It is to be noted that in a unit or single cavity system, there is no need for such an elaborate standoff system because the injection cavity mounted onto the fixed platen, and the nozzle mounted onto the ram block, are sach mounted on the center line of the machine. Also, the faces of the platen and ram block are rigid and do not deflect ~rom their vertical planes. In the multi-injection nozzle machine ,~1 -of this invention, such as the one shown in the drawings, wherein there are eight inclividual injection nozzles mounted in a pattern spread out from the absolute center line of ~he runner block and machine, wherein each nozzle has a very short combining area in its central channel, and wherein a thin injection cavity bolster plate 9S0 is needed between the runner block and the inject:ion cavities 102 and injection cavity carrier blocks 104 to carry the cavities and carrier blocks and to prevent or reduce heat loss From t~e former to the latter, there is a great need that both the injection cavity bolster plate and the entire runner face be protected from the clamping force o~ the moveable platen relative to or against the fixed platen. Also, in a multi-nozzle machine such as the one shown, wherein there is an operating temperature differential between the injection cavities and ~he runner block which often varies hecause they are separate entities and perform different functional process requirements, there is a need for the previously mentioned flat sliding faces on the cavities and nozzle caps, and .or the rigidized structure utilized herein which not only bear~
clamping loads but permits expanding metal of the runner block and its components to freely float within it.

The portion of the rigidi~ed struc~ure through which the mass of expanding metal freely floats is the support means or nozzle shut-off assembly generally designated 899, which is comprised of the sleev~ cam base cover 901, sleeve cam base 90G, pin cam base cover 894, and pin cam base 892.
All are fixed and locked solidly to and between the in~ection cavity bolster plate 950 and fixed platen 282. As for the ma.nner in which the nozzle shut-off assemhly is tied together as a unit, injection cavity bolster plate 950 is rigiaized through bolts 960 which extend through the plate and through stand-offs 962 and is threadedly secured to sleeve cam base cover 301. Looking at the upper portion of Fig. 31, sleeve cam base cover 901 is tied by bolts 910 to sleeve cam base 900, whiclh is tied by bolts 970 to pin cam base 894, which in turn, by bolts 971, is tied through cam plate ba~e 892, and - 1~ -'~5~

threadedly secured to fixed platen 282. In this manner, the injection cavity bolster plate 350 is rigidized and the nozzle shut-off assembly is tied together as a unit. qhe gap between the front face of s:Leeve cam base cover 901 and the runner block, and between the main bore 973 carved through the components of the nozzle shut-off assembly and the oil retainer sleeve, permits the runner extension to float through the assembly.

The Force Compensat1o~

Another main feature of the total system which provides for the constant, uniform and full aspects of the effective operational pressure contact seal at the injection noz~le-injection cavity sprue interfaces is the force compensating system or apparatus and method of the invention which compensate ~or or absorb and offset the rearward separation force, which can be about four tons, created by th~ forward iniection of polymers through and back into the multiple injection nozzles during the injection cycle, and any rearward displacement caused by th~ thermal expansion of th~ floating runner block and runner extension which may be from about .OlS inch to about .025 inch. The separation force, which alone could cause a separation and leakage at the interface between th~ injection nozzles and cavity sprues, and any thermal expansion displacement, is transferred axially through the runner block, runner extension, and manifold extension 266 to the entire ram block 245. The separation force of about four tons is calculated by multiplying the area of a single nozzle gate times the number of nozzles in the injection machine, here eight, times the maximum injection pressure ~about 11 tons). Thermal expansion is allowed to occur and is not relied on to obtain and maintain an effective pressure contact seal between the injection nozzles and cavity sprues. By compensating for and absorbing these rearward forces exerted on the ram block with an appropriate, constant, sufficien~ or greater forward force, the force compensating structure and method obtain and ~S
_ 3 _ ~ IE;2~

maintain an on-line constant, effective pressure contact seal of all injection nozzle sprue faces fully against and about the injection cavity sprue faces. The force applied in the forward direction to the a]pparatus must be and is applied constantly and uniformly so that it does not cbange with thermal expansion as it does in conventional systems, and so that during operation of the machine, whether or not during an injection cycle, each o~E the five manifold extension nozzles of the set and each of the eight injection nozzles of the set is respectively on a substantially vertical plane and receives the same, or substantially the same, respective, constant forward force, such that there is a uniform, ~ull and balanced force applied to, and an effective pressure - contact seal for, each nozzle of each set. Although the constant, uniform, greater forward force can be applied by any one or more suitable means at one or more locations on an injection molding apparatus, preferably, the means is hydraulic and is compri~ed of at least one, preferably a plurality, of hydraulic cylinders. For the apparatus shown ln the drawings, a plùrality of hydraulic cylinders are employed at various strategic locations to apply a sonstant forward force to or through and along the absolute center line of the overall apparatus, wbich is the axial center line of each of entire ram block 245, runner extension 276, and runner block 288. In this manner, they provide the uniform force which ef~ects the full and complete pressure contact seal for each nozzle of each set. The hydraulic cylinders employed in the force compensation apparatus and method of this invention include drive cylinder 340, ram block sled drive cylinder 341, and clamp cylinders 936.

Referring to Figs. 11, 12, 14, 18, 98, 119 and 120, during operation of the apparatus, each of the cylinders 208, 210 for respective Extruder Units I, II, and cylinder 212 for Unit III, each driven forward by its own respective hydraulic drive cylinders 341 (~or Units I and II) and 340 (for Unit III), maintains a pressure contact seal between their r~spective nozzles 213, ~15 and 248 and rear rAm manifold ~G

sprues 223, 221 and 249. Drive cylinder 340 exerts its forward force through cyli~der 20~ and nozzle 215 directly on and along center line of entire ram block 245. Ram block sled drive cylinder 341, fixedly connected to sled bracket 336, in turn tied to ram bLock 228, pulls the entire ram block 245 forward on its center line. Each clamp cylinder 986 is mounted by suitable means onto the forward face of fixed platen 282 an equal radial distance from and on a plane, here the horizontal one, which runs through the absolute center line o~ the apparatus. ~ach clamp cylinder is one of a matched palr and has a cylinder rod and cylinder rod extension generally designated 988 which passes through a bore 990 in the fixed platen and through bore 991 in a side end portion of forward ram manifold 244. A holding pin 992 dropped into a receiving hole in each cylinder rod extension forms a stop against the back edge of the forward ram manifold. The clamp cylinders clamp or pull the entire ram block toward fixed platen 282. They exert their force through the center line of the entire ram block. Thu , the drive and clamp cylinders individually and in combination ~ull the enti~e ram block forward on its center line and force manifold extension 266 against runner extension 276.
The force applied by the cylinders through the center line o~
the entire ram block ie transferred to, through, and along the center line of the runner exten~ion. This effects and maintains a uniform, full, constant, effective pressure contact seal ~etween manifold extension nozzles 270 and runner extension nozzle pockets 272 and maintains alignment of the center lines o~ the respective communicating flow channels 220, 222, 250, 257 and 258. The force from these cylinders, applied through the cen~er line of the manifold extension, is transferred through and along the absolute center line, which is common to the center lines of runner extension 276 and runner block 2B8, to the entire flat face of each injection nozzle tip mounted within the runner block. Since all injection nozzles are of a controlled, matched length and are mounted to substantially the same depth up to a vertical plane within the runner block, all ~7 ! j,_`~

~2~ 5~7 portions of the flat face of the noz21e tip of each injection nozzle which bear against t:he juxtaposed injection cavity sprue do so with the same uniform~ full and balanced pressure. Applying the forward forces other than along the center line at points not substantially equidistant from the center line in an insufficiently rigid runner, would tend to create an unbalanced cantilever effect which would prevent obtaining and maintaining a constant uniform, full, effective contact pressure seal for all mani}old extension nozzles and all eight injection nozzles. The structures employed to apply these ~orces should not create any significant heat loss from the runner block. The center line transferral of force through tbese structures may, despite the larger size of the runner block, assist in maintaining injection nozzle-cavity sprue center line alignment.

With respect to the actual functioning o~ the cylinders as compensators during the operation of the apparatus, the rearward injection separation pressures exerted against the injection noz~les and through th~
floatin5 runner block and runner exten~ion and thr~ugh manifold extension, plus a~y thermal expansion pressure exerted ~hrough the runner extension, force the entire ram block and the iled drive bracket 336 to which it is attached, in the rearward direction. While it is not known which of cylinders 340, 341, and 986 absorb what portion of the total rearward pressure, it is believed that the t~o drive cylinders, while sufficient to handle thermal expansion pressures, are not, because of their size, sufficient to handle the combined rearward pressures and that at least some, perhaps most, of the injection separation pressure is compensated for, absorbed and o~fset by clamp cylinders 986.
As the injection machine operates through repeated injection cycles, the clamp cylinders, acting as shock absorbers, exert a forward pressure which is at least sufficient to compensate for or absorb the rearward pressure changes. For example, if the runner extension is moved rearward and the entire ram block move~s rearward, the clamp cylinders react and ~heir /~
- ~6 ~256~ii7 cylinder rods retract and pull the entire ram block forward against the runner extension. The cylinder~ absorb the rearward force and offset it with a greater forward force, keep the manifold extension nozzles and runner extention pockets in seated contact, and impart a forward force against the back end of the runner extension which in turn forces the runner block forward to maintain a constant effective pressure contact seal between all of the injection nozsle tip fa~es and all of the injection cavity sprue faces.

While displacement clamp cylinders 986 absorb perhaps most of the injection separation pressure, it is to be noted that all of the drive and clamp cylinders cooperate with one another to provide the necessary total force compensating system.

A substantially uniform and full forward force on each of the manifold extension nozzles and at and about each o~ ~he eight injection nozzles is obtained due to the strategic, uniform application of force on or through the absolute center line of the apparatus. For the apparatus sho~n in the drawings, it would be difficult to employ only one or two larger, stronger drive cylinders and eliminate the clamp cylinders, because it would be difficult to position such large drive cylinders to enable them to exert their ~orward force at or ~through and along the absolute center line. If the force were exerted through a point lower than the center line, a cantilever effect would be created wh~rein the pressure exerted through nozzles near the bottom of the star pattern of the manifold extension would be greater than through those near the top of the pattern. This could cause leakage through the upper nozzles and inoperability of the injection apparatus. Each clamp cylinder 986 is pressure set so that its pressure, combined with that of the drive cylinders, exert a constant force greater than the separation pressure. The pressure set can be obtained by any suitable means, for example, by a connection onto another pressure line having sufficient pressure or as obtained herein by a ,~7 -~L~7 -r3~' conventional hydraulic pressure controlling valve (neither shown). The clamp cylinders are controlled by a conventional flow control valve (not shown) to retract at a slow rate until the set balanced pressure is obtained in each clamp cylinder. If the set balanced pressure were not obtained in each clamp cylinder, there would be a dif~erence in pressure between them which would also provide an undesirable cantilever effect.

Descri~tion of Process The process begins with the plasticizing of the materials for each of the layers o~ the injected article. In the preferred embodiment, three separate plastic materials structural material for the inside and outside surface layers A and B, barrier material for the internal C layer, and adhesive material for internal layers D and E -- are plasticized in three reciprocating screw extruders~
Pla tici~ed m~lt from each of these extruderg is rapidly, but intermittently, delivered to fiv~ individual ram accu~ulators. The structural material extruder feeds two rams; the adhe~ive material extruder feeds two rams; and the barrier material ext~uder feeds one ram. Each of the five rams then feeds the polymer melt material exiting ~rom it to re~pective flow channels for each melt stream, as previously described, wh~ch lead to each of eight nozzles for eight injection cavities to form eight parisons each of whose walls is formed from ~ive con~urrently flowing polymer melt material streams. The process provides precise independent control over five concentric concurrently flowing melt streams of polymeric materials being co-injected into the eight cavitias. As is more ~ully described below, this is accomplis~hed by controlling the relative quantity of, the timing of release of, and the pressure on, each melted polymeric material.

Each of the five separate polymer melt material streams for layers A, B, C, D and E flows through a separate ~0 - ~8 -passageway for each stream in each of the eight nozzles.
Within each nozzle, each passageway for each of streams A, B, C, D-and E terminates at an exit orifice within the nozzle, and the orifices in streams B, C, D and E communicate with the nozzle central channel at locations close to the open end of the channel. The orifice for stream A communicates with the nozzle central channel at a location farther from the channel's open end than thle orifices for the other streams.
Each nozzle has an ~ssociated valve means having at lea~t one internal axial polymer material flow passage~ay which communicates with the nozzle central channel and which is also adapted to communicate with one of the flow passageways in the nozzle, which in the preferred embodiment contains material for layer A. The valve means is carried in the nozzle central channel and is moveable to selected positions to block and unblock one or more of the exit orifices for the materials of layers A, B, C, D and E. The valve means further comprises means moveable in said axial passageway to selected ~ositions ~o interrupt and restore communication for polymer flow ~Detween the axial passageway and a nozzle passageway. In the preferred embodiment, the valve means comprises a sleeve, which is moveable in the noz21e central channel to block and unbloc,; the ori ices for each of the streams B, C, D and E, and a pi~ which is moveable in thè
passageway in the sleeve to interrupt and re tore co~munication for flow of the polymar melt mate~ial flow stream throug~ the orifice or stream A between the sleeve passageway and a nozzle passageway.

The drive means previously described ac~uates the p~eferred sleeYe and pin valve means to selected positions or mode~ for selectively blocking and un~locking the orifices, includincl the aperture in the sleeve which is regarded as the orifice f.or the stream of layer A material. In the preferred embodiment, there are six modes. In the first mode, illustrat:ed schematically in Fig. 121, the sleeve 800 blocks all of the exit orifices 462, 482, 502 and 522, and the pin 834 blocks aperture 804 in the sleeve, interrupting /~/

communication between the internal axial passageway 803 of the sleeve and the nozzle passageway 440 associated with it.
NQ polymer flows. In the second mode, illustrated scbe~matically in ~ig. 122, the sleeve blocks all of the exit orifices and the pin is retracted to establish communication between the axial passageway 803 in the sleeve and the nozzle passageway 440, whereby the mate~rial for layer A is permitted to flow from the nozzle passageway`through the aperture 8~4 in the sleeve into the internal axial passageway 803 in the sleeve which is located in the nozzle central channel 546.
In the third mode, illustrated schematically in Fig. 123, the sleeve unblocks the orifice 462 most proximate to the open end of the nozzle central channel, allowing the material for layer a to flow into the channel, and the pin does not block the aperture in ~he wall of the sleeve, permitting continued flow of layer A material. In the fourth mode, illus~rated schematically in Fig. 124, the sleeve 800 unblocks three additional orifice~ 482, 502 and 522, permitting the flow o~
mat~r$als for layers C, D and E into the nozzle central channel 546, and the pin 834 ~emains in the position which unblocks the aperture 804 in the wall of the ~leeve, permit~ing continued flow of layer A material. In this mode all ~ive of the material streams are allowed to flow into the nozzle central channel. In the fifth mode, illustrated schematically .in FigO 125, the sleeve 800 continues to unblock the orifices for the materials of layers B, C, D and E and the pin 834 blocks the aperture 804 in the wall of the sleeve 800 to interrupt communication between the axial passageway in the sleeve and the nozzle passageway g40, whereby the flow of layer A material into nozzle centra~
channel 546 is blocked. Positioning the pin and sleeve in this mode permits knitting or joining together of the material ~or layer C, forming a con~inuous layer of that material ;in the injected article, In the sixtb mode, illustrate~d schematically in Fig. 126, the pin 834 continues to block t:he aperture 804 in the wall of the sleeve 800 and th~ sleeve~ unblocks the orifice 462 most proximate to the open end of the noz~le cen~ral channel 546, whereby only the - ~0 -~625;~7 material for layer B flows into the channel. Positioning the pin and slaeve in this mode permits a sufficient flow of the material for layer B to enable it to knit or join together and form a layer which com]pletely encapsulates, among other layers~ a continuous C layer.

In the preferred embodiment, a complete injection cycle takes place when the drive m~ans for the valve means, the pin and sleeve, operate to move the valve means sequentially from the first mode to each of the second through sixth modes and then to the first mode. It is also preferred that the tip of the pin be proximate to the open end of the nozzle central channel when the sleeve and pin are in the first mode. ~aving the pin at this position substantially clear the nozzle central channel of all polymar material at the end of each injection cycle and causes a s~all amount Gf the material of layer A to overlie layer B at the sprue.

Figs. 123 and 124 schematically show the relative lo~ation and dim~nsional relationship among the pin 834, slaeve 800, nozzle cap 438, and the orifices 462, 482, 502 ~nd 522 for polymer flow formed by cap, outer shell 436, second shell 434, third shell 432, and inner shell 430O In the~e figures, the "reference" point ~O~ is the front face 596 of the no~zle cap, rlp~ is the distance of the tip of the pin from the reference, and "5~ is the distance of the tip of the sleeve from the reference. The dimensions shown in Figs.
123 and 124 are in mils. The ront face 596 of the nozzle cap lies in a plane at the front end of channel 595 in the nozzle C2p. The portion of the plane along front face 596 which int:ersects channel 595 is the gate of the nozzle.

Table II gives the positions of the tip of the pin and the t:ip of the sleeve from the reference as a function of time in centiseconds during a typical injection cycle for the eight-ca~ity machine previously described. The distances from the reference are in mils.

/q~

~2~i~25 ~

TABLE II
POSITION OF PIN AND SLEEVE
AS A FUNCTION OF TIME

TIME PIN SLEEVE
(Centiseconds) p _ _ _ s 24.4 1987 175 49 198~ 580 121 1987 58~

140.9 521 175 145 487 . 175 ~70 112 175 Fig. 138 and Table III show the timing se~uence o~
polymer melt stream flow into the noz~le central channel, as determined by timed movement of the sleeve and pin to the selected positions or modes previously described, for an injection cycle o~ the eight-cavity machine previously de~cribed. For polymer A, the opening and closing times refer.to opening and closing of aperture 804. For polymers 9, C, D, and E, the times refer to opening and closing of res~ective orifices 462, 502, 522, an~ 482.

TABLE III
POLYMER FLOW_TIMING SEQUENCE

OPE~ING (Time CLOSING (Time in centiseconds) in centiseconds) POLYMER STARTS AT COMPLETE AT STARTS AT COMPLETE AT
A 13.2 15.8 121.0 122.5 B 24.4 27.8 137.8 140.9 ,~ _ TABLE I I I
POLYMER FLOW TIMING SEQUENCE (Continued) OPENING ('rime CLOSING (Time in centiseconds) in centisecondsl POLY~SER STAR~S AT COMPLETE AT STARTS AT CO~PLETE AT
_ _ _ _ ._ _ C 46.7 46.9 131.9 L32.1 D 47.3 48.0 130.9 131.5 E 46.0 46.3 132.4 132.6 At the beginning of the i~jection cycle, the pin and sleeve are in the fi st mode ~Fig. 121). No polymer material flows. The pin is withdrawn from the reference position where its tip was 112 mils from the front face of the nozzle cap, opening to the gate of the nozzle a short unpressurizea cylindrical ehannelO The pin continues to be retracted and at 13~2 centiseconds the pin begins to unblock the aperture 804 in the sleeve through which the stream of polymer A
material flows, and the opening of that aperture i~ co~pleted at 15.8 centisecon~s. The pin a~d the sleeve are now i~ the second mode. The polymer A material is under pressure and i~mediately ~ills the unpressurized cylindrical chan~el ~within the sleeve and central channel of the no~xle), flows th~ough the gate and begins to enter the injection cavity.
At 20 centiqeconds movement of the pin ceases and its tip is Located 1.987 inch from the reference, as further shown in Pig. 122 a~d ~able II. At 24.4 centiseconds withdrawal of the sleeve begins and the sleeve begins to unblock the circumferential orifice 462 for polymer B, and the opening of the polymer B orifice is completed at 27.8 centiseconds. The pin and sleeve are now in the third mode. ~eing pressurized, the layer B material displaces the outer portion of the cylinder of material A and becomes an advancing annular ring overlying the central strand of A material. The strand of A
surrounded by the ring of 3 fills the gate and begins to enter the injection cavity. At 30 centiseconds, retraction of the s:Leeve stops and its tip is 270 mils from the reference. ~he next step is the rapid sequential release to /~S

the nozzle central channel of the materials for layers E
(adhesive), C (barrier) and D (adhesive) as concentric annular rings surrounding the core of A material but within the outer annular ring of :Layer ~ material. Thus, at 4 centiseconds the ~leeve begins to be further retracted, opening of the orifice 4B2 for polymer E star s at 46.0 centiseconds and is complel:ed at 46.3 centiseconds, opening of the orifice 502 for polymer C starts at 46.7 centiseconds and is completed at 46.9 centiseconds~ and opening of the orifice 522 ~or polymer D starts at 47.3 centiseconds and is complete at 48 centisecondsO The pin and sleeve are now i~
the fourth mode. All of polymers A, B, C, D and E are flowing at five concentric streams through the gate of the nozzle and into the injection cavityO The material for layer A (to form the inside structural layer of the injected article~ flo~ as the in~ermost stream. Surrounding it, in order, are annular streams of the materials for layers D, C, E, and B. Although the rate of flow and thickness of the three streams D, C, and E are each independently controllable, th~y move in the preferred embodiment generally as though they were a single layer. This multiple-layer stream is position~d between stream A and ~ so that when the ~ive flowing streams have entered into the injec~-ion cavity, the multiple-layer D C-E stream is located substantially in the center of the o~erall flowing melt stream, on the fa~t streamline where the linear flow rate is greatest, and the multiple layer stream displaces part of and travels faster then the two layels, A and B, of container wall structural material~, reaching the flange portion of the injected article by the end of the injection cycle when the flow of all materials in the injection cavity has stopped.
Retraction of th~ sleeve stops at 49 centiseconds at which time its tip is 580 mils from the reference ~Fig. 124).

The closing sequence of the injection cycle is as follows. At 121 centiseconds, the pin is moved toward ~he reference and lt begins to close the aperture in the sleeve and at 122.5 centiseconds has completely closed the aperture qh ~i6~i7 to stop the flow of polymer A into the nozzle central channel. The pin and sleeve are now in the fifth mode (Fig.
125). Polymer B, C, D, and E are flowing. The pin continues to move toward the open end of the nozzle central channel, and at 130 centiseconds, when its tip is 612 mils from the reference, its rate of forward movement is decreased.
Movement of tbe sleeve toward the opan end o~ the no~le central channel commences at 13C centiseconds. At 130.9 centiseconds, the sleeve begins to close the orifice for polymer D and the ori~ice is completely closed at 131.5 centiseconds. At 131.9 centiseconds, the sleeve begins to close the orifice for polymer C and the orifice is completely closed at 132.1 centiseconds. At 132.4 centiseconds, the sleeve begins to close the orifice for polymer E and the orifice is cvmpletely closed at 132.6 centiseconds. The pin and the sleeve are now in the sixth mode ~Fig. 126). Only poLymer B is flowing into the nozzle central channel. The pin is still moving ~oward the open end of the noz21e central ~hannel. At 133 centiseconds, when the sleeve is 320 mil~
from the reference, there is a decrease in the rate of forward movement of the sleeve. At 137.8 centiseconds, the sleeve begins to close the orifice for polymer B and the orifice is completely clo ed a 140.9 centiseconds. ~orward movement of the sleeve stops at that time, when its tip is 175 mils from the re~erence. No polymer flows into the nozzle central channel. At 145 centiseconds the rate of forward mo~ement of the pin is increased. Forward movement of the pin stops at 165 centiseconds when its tip is 112 mils fro~ the reference. The pin and sleeve have returned to the first mode.

In the preferred practice of the method of this invention, the 10w of polymeric material out of the open end of the no2zle central channel into the injec~ion cavi~y at the beginnlng of the injection cycle is such that the materials i-or layers A and B enter the injection cavity at about the same time in the form of a central strand of the material for layer A surrounded by an annular strand of the I q~
~ ~5 --~2S~

material for layer B. . In the embodlment aescribed above, the ma~erial for layer A enters the sprue of tbe injection cavity in advance of the combined central strand of A surrounded by the annular strand of B. Where, as in the preferred embodiment which forms a very thin wall article, tAe flow cross-section in the injec:tion cavity is very narrow, the material of layer A which first flows into the cavity will come into contact with the outer wall of the cavity aq well as with the core pin within the cavity, causing the formation of a very thin, almost optically invisible, layer of the material on the outside surface of the injection blow molded article. If polymer A ànd polymer B are the same polymer or are compatible polymeric materials, either one of polymers A
or B may sequential~y enter the in~ection cavity, and in that circumstance the small amount of polymer A which may be on the outside surface of the injected article, or the small amount of polymer B wh~ich may be on the inside surface of the injected article, will not interfere with the formation of the article or ~ts ~unctioning~ ~owever, the present invention provides precise independent control o~ar the flow o~ those polymer streams so that i it is desired not to have polymer A material be exposed to the external environment or not to have polymar B material exposed to the environment inside of the injected article or the injection blow molded article, such structure may be achieved by the present invention. Therefore, it will be understood that the modes o~ polymer flow and positions of the valve means, described above, are those for the p~eferred embodiment, but the invention in its broadest aspect is not limited thereto~

By controlling the location of the in~ernal layer or layers within the thickness of the flowing five-layer pla~tic melt, the proces3 is able to distribute the internal layers uniformly and consistently throughout each of a plurality of injection cavities and out into the flange of each of a plurality of injection molded parisons while keeping the internal layers generally centered within the outer, structural plastic melt layers.

'7 It is important that internal layer C ~and, if present, internal layers D and E) should extend into the marginal end portion of th~_ side wall of the injected molded article, preferably substantially equally, or uniformly at substantially all locations around the circumference of the end portion, especially when layer C comprises an oxygen-barrier material and the article is intended to be a container for an oxygen-sensitive proouct such as certain foods. This is achieved in part by controlling the initiation of flow of the polymeric melt material flow stream which forms the internal layer. It is desirable to have the flow of the polymer material of that layer commence uniformly around the circumference of the orifice for that polymer. It is also highly desirable to have the mass rate of flow of the respective polymer material flow streams forming the inside (polymer A) and outside (polymer ~3 structural layers of the article be uniform circumferentially as they are flowing in the noæzle central channel at the time when flow o~ the polymer stream for internal layer C is commenced. Tha previously-described nozzle with valve means permits establishment both of the proper flow of the polymer streams forming the inside and outside structural layers, at the time of commencement of flow of the polymer stream forming the internal layer, and of the proper flow of the stream o~
internal layer polymer itsel~

There are two immediate or direct sources of non-uniformity or bias in the extension of the internal layer into the marginal end portion of the side wall of the article. The first source which we shall refer to as ~time bias~ m~y be defined as the condition in which the time of commencement of ~low of internal polymer melt material C is not uniform circumferentially around the polymer C orifice.
Time bias in the flow of the polymer C stream, unless corrected elsewhere in the system or unless accommodated by foldover, as de-~cribed below, will usually result in a failure of the internal oxygen-barrier layer C to uniformly extend into the marginal end portion of the side wall at /q~
- ~7 -~5~

substantially all circumferential locations thereof.

Two causes of time bias are non-uniform pressure of polymer C in its conical flow passageway near the C orifice and non-uniform ambient pressure in the nozzle central channel near the C orifice.

Non-uniform pressures of polymer C in its passageway can result primarily from differences among various portions of the ~low passageway in time response of the polymer to a ram displacement. In particular, the pressure generated by the ram displacement movement will, in general, be experienced sooner at the circumferential portion of the Grifice corresponding to the point of entry of the feed channel than it will on the opposite side of the orifice.
Since polymer C will flow into the central channel as soon a~
i~ pressure in the orifice exceeds the ambient pressure in the combini~g 3rea or eye of the nozzle, a difference in time response will result in a circumferential non-uniformity in the ti~e at which polymer C enters the cen~ral channel. Thi~
difference in initial time response can be mitigated by the design of melt pools and chokes As discussed elsewhere, melt pools and chokes can also be designed to circumferentially balance the mass 10w rate later during the cycle when tbe flow i3 fully established. ~owever, it is extremely difficult to design melt pools and chokes which result in complete uniformity of time response and in complete balance of ~low later in the cycle. Dimensional tolerances and non-uniform temperatures within the C layer material flow passageway can also affect the uni~ormity of time response.

If the ambient pressure within the nozzle central channel, proximate to the C orifice, is not uniform around the circumference of the flow stream, this will also result in time bias. If the pressure of C is gradually rising as a result of a ram displacement, C will begin ~o flow into the central channel sooner in that circumferential area in which ~0 .

~s~

the ambient pressure is lower. Non-uniformities in the ambient pressure can have several causes~ In particular, non-uniformities in the flc>ws or in the temperatures o~ the other layers, particularly B, will result in non-uniform ambient pressure in the eye~ of the nozzle.

The se~ond source of a bias in the extension of the internal layer into the marginal end portion of the side wall of the article shall be re~erred to as ~velocity bias. n Velocity bias may be defined as the condition in which the rate of progre~sion of the buried layer toward the leading edge varies around the circumferenceO resultlng in a further advance in some sections than in others.

In understanding this pbenomenon it is useful to introduce the concept o~ streamlines. In laminar flow, one can define a streamline as a line of low whioh represents the path which each polymer ~olecule follows from the time it enters the nozzle central channel until it reaches its final location in the injection molded article. Streamlines will ~low at ~arious velocities depending on their radial location, the temperatures of the mold cavity surfaces, the temperature of the various pol~mer streams, the time of i~troduction Lnto the eye of the nozzle, and the physical dimensions of the msld cavity. For example, a streamline which is located very close to the mold cavity walls once it pas es into the mold cavity will flow slower than an adjacent streamline which is more remote from the mold cavity walls.
If the C polymer material enters the nozzle central channel on a faster streamline at one circumferential location than it does at another location, the C polymer material will be more advanced towards the marginal end at the first location. Since the C polymer material is introduced at or near the inter~ace between the A and a layers, the radi?l location of the C flow streams will be determined by the relative mass flow rates of the A and 3 layers at each poi~t cf the circumference of the flowing stream. velocity bias will therefore result i~ the flow of these layers, in ~(' ,~g g ~2~S25;~7 particular the B layer, is not circumferentially uniform.

Circumferential non-uniformit~es in the temperature of the polym2r streams or of the mold cavity ~urfaces can also result in velocity bias. Temperatures affect the velocities of the various streamlines because of the effect of cooling on the polymer viscosity near the mold surfaces.
It should be noted that circumferential non-uniformities in the temperaturas of the A or B layers, in particular, will affect the position of polymer C near the m~rginal end.

It should be noted that the various types and causes of bias are algebraically additive; that is, if both time bias and velocity bias are present,-the net effect could be either greater than or less than the effect of either type o~
bias by itself. In particular, if the time bias and velocity bi~s both tend to result in a retarded flow o~ C polymer at the same circunferenti~l location, the net bias will be gr~ater. If time bias tends to retard the flow of polymer C
at a ciroumferential loc~tion in whi~h velocity bia~ tends to advance its flow, the net bias will be reduced.

Similarly, one cause o velo~ity bias could either ~ompensate for the effect of another cause of bias or add to that e~fect. It will be obvious to o~e skilled in the art how the effects described above could be arranged so as to have the effects tend to partially compensate for each other. Since such compansation of biases will tend to be very spec$fic to each article shape and choice of polymer t however, the preferred embodiment of this invention i9 to minimize each oause of bias through features of the apparatus and of the process.

As has been described above, circumferential non-uniformity in the flow of ~ polymer can cause non-uniformi ies in the final axial location of layer C
through both time bias and velocity bias. The time bias results fro~ the non-uniform ambient pressure in the nozzle .

~1r~L

~2~

central channel and the velocity bias results from the non-uniformity in the radial location of layer C as it is determined by the mass flow rate of layer B.

Circumferential non-uniormities in the flow of B
polymer material may be minimized by selection of a choke structure of the nozzle ~hell 436 for layer B material to make the flow of the layer B material more uniform around the circumferenc2 of the orifice. The nozzle shell structure is also made such that a longer and wider primary pool of layer B material is formed, as at 468 at the melt inlet, to obtain a larger flow section in order to reduce the resistance to flow of the polymer material from the entry side of the feed channel to the opposite side. Incorporation of an eccentric choke will assist in balancing the resistance to flow within the nozzle passageway. Interposition of 2 uniform, large flow restriction close to the orifice will aid by tending to mask any upstream non-uniformities of flow. Further, non-unifor~ ambient pressure in the nozzle central chann~l at tbe moment of co~mencement of flow of layer C mate~ial may be minimized by reducing ~he pressure on the layer B material, or stopping its flow momentarily, just prior to commencemen~
of the flow of the C material. This may be accomplished by reducins or halting ram movement on the B layer material, and will tend to dampen out pressure non-uniformities in the nozzle central channel caused by non-uniformity of ma ~ flow of layer B and will tend to minimize the variation of pressure of layer B material or layer A material, or both, circumferentially around the nozzle central flow channel at the location where layer C material enters the flow chann*l.

Non-uni~ormity of the time of ~he qtart of flow of the stream of polymer C material around the circumference of the orificle may be minimized by having the leading edge of the polymer C flow stream penetrate as rapidly as possible into the already-flowing stream of layers B and A and by having the mass rate of flow of layer C material through its orifice be uniform around the circumference of the orifice~
.

This may be achieved by valve means in the no2zle central channel which blocks the layer C material orifice until the moment when initiation of flow is desired. Pressurization of the layer C material prio~e to the time when the valve means unblocks the orifice greatly assists in achieving the desired rapid, uniform initiation of flow of layer C material.

Certain other features o~ the previously described structure of th~ present invention assist in minimizing time bias of the flow of the stream of layer C material. ~he conical, tapered passageway 518 (Fig. 50) for layer C
material in the nozzle provides a symmetrical reservoir of pressuri~ed polymer melt material downstream of the concentric choke 506 (Figs~ 50 and 55) and adjacent to the orifice. The taper serves continuously to provide a reservoir closer to the orifice. Eccentric choke 504 and concentric choke 506 in combination with primary melt pool 598, secondary melt pool 512 and final melt pool 516 assist in providing uni~orm flow of the ~tream of polymer C material around the circumference of its orifice (Pig. 50).

It is desirable that the volume of polymer in the central channel of the nozzle be kept small in order to facilitate ease of control of the start and stop of the flow streams. Accordingly~ the diameter of the noæzle central channel should be relatively smallO Likewise, the axial distance from the nozzle gate to the Earthermost removed polymer entry flow channel into the nozzle central channel should be kapt small.

At any given position around the circumference of the orifice for the polymer of the internal layer C, the polymer material will begin to flow when its pressure, Pc~
is great:er than the ambient pressure, Pamb, in the channel, which is the combined pressure from that of the stream of polymer of the inside structural layer, PA, and the pr~ssure! from the stream of polymer of the ou~side structural layer, E~B. The onset of flow of the stream o~ polymer C

~0~

~5~7 for the internal layer will be uniform, i.e~, will start at the same time, at all positions around the circumference of the orifice for layer C, if the pressure of the polymer of that layer, Pc~ is uni~orm around the orifice and if the ambient pressure, Pam~, in the nozzle central channel of the flowing streams A and B, of the inner and outer structural layars respectively, is constant at all angular positions around the flowing annulus. If Pamb i~ not constant, the onset of flow of layer C will be uniform if the pressure distribution at the leading edge of layer C, as a function of radiu and angular location in the nozzle central channel, matches the ambient radial and angular pressure distribution of the already flowing A And B streams at the axial location in the nozzle central channel at which the C
layer is introduced.

These conditions are ~ifficult to achieve. ~hen PC is not uniform around the orifice, or when the ambient pressure in the nozzle central channel is not constant, time bias of the leading edge of the entering polymer C flow st~eam will tend to occur, ~ut it may be minimized by cau~ing a rapid rate of build-up of pressure, dPC/dt, in layer C as i enters the no~zle central channel.

While a rapid ram movement will cause a rapid build-up of pressure near the ram~ it has been found that the resulting d~C~dt in the no~zle central channel at the time of introduction of layer C decreases as the runner distance frsm pressure source to nozzle central channel increases~ A
high baseline or residual pressure in the runner system has been found to increase dPC~dt in the nozzle cen~ral channel. ~herefore, to obtain the desired, rapid rate of build-up of pressure in layer C in the nozzle central channel, in response to a rapid pressure build-up at thè end of the runner adjacent the pressure source, the length of the runner should be shortened and the residual pressure of C
increased. ~owever, relatively long runners are utilized in multi-cavity machines, and there is an upper limit to the .. ~_ pres~ure of C above which an undesirably large mass of polymer C is obtained at its leading edge. Further, when long runners are employed, as in a multi-cavity machine, the flow rate of polymer into the nozzle central channel is the result both o~ flow due to physical displacement o~ a sorew or ra~ at the far end of the runner and flow due to decompreRsion of polymer in the runner and nozzle, if the polymer has been prepressurized. These factor~, coupled with the effects of damping in the polymer in the runner t cause a rapid rate of increase of pressure in the polymer at the and of the runner adjacent the pressure source to deteriorate into an undesirable gradual rate of pressure increase at the other end of the runner and at the site of entry of the polymer into the nozzle central channel. (See the discussion regarding Fig. 139.) As a result of these constraints, it is difficult, particularly in a multiocavity machine, to achieve the desired dP~/dt and even more difficult to achieva substantial uniformity of dPC/dt around the circumference of the ori~ice of ~olymer C.

As mentioned above, the desired uni~ormity is facilitated by the combination o~ 2 symmetrical pre~erably tapered, pressurized reservoir of polymer C material wi~hin the nozzle passageway for the materlal adjacen~ to tha ori~ice, with valve means which selectively blocks and unblocks the orifice. The pressure PC may be increa~ed to a level which overpowers any radial or angular non-uniformities of pressure distribution in the flowing streams A and B at the location of the layer C ori~ice in the no2zle central channel. It ha~ been found that the layer C
material should be pressurized to a level greater than the materials of layers A or B. The upper limit o pressurization of C ma~erial i9 the level at which therP is obtained an undesired mass o~ C material at the leading edge of its 10w stream.

'rhese pre~sure variations are illustrated in Figs.
127 and 128 in which the ordinate is pressure, the abscissa ~0 Ç~

i'7 is time, and in which the ambien~t pressure, Pamb, of the flowing streams A and ~ in the nozzle central channel is assumed to be radially and angularly constant at an axial location in the channel about the orifice for layer C.

Fig. 127 illustrates the effects of a relatively slow rate o~ build-up of pressure in the layer C material as it enters the nozzle central channel and reaches the ambient pressure at different times, tl and t2, at two di~ferent angular locations. In Fig. 127, Pcl, is a plot of the relatively slow preYsure build-up of layer C at a first given angular locztion at the C orifice as a function or time, while Pc2 is a plot of the relatively slow pressure build-up of layer C at a second given angular location at the C orifice as a ~unction of time. Small non-uniformities of Pc~ as a function of angular location, result in a relatively large difference in time, t2 ~inus ~1~ b~tween the on-~et of flow of layer C at the two respective angular locations, causing a significant time bias of ~he leading edge of layer C from one angular location to another. ~ig.
128 illustrates how the time bias i5 reduced by increasing the rate of build-up o~ pres~ure in layer C. In Fig. 128, Pcl is a plot of the relatively faster pressure bui}d-up at the first given angular location as a function of time, while Pc2 is a plot of the relatively faster pressure build-up at the second giv~n angular locatiQn as a function of time. As d~C/dt increases, the difference b0tween t2 and t decreases.

The relationship among the pressures of ~he layer A
material, the layer B material and the layer C material at the beginning of the injection cycle and during the injectlon cycle will now be described. ~n the following description, the ter~ ~orifice for layer A material" refers, with regard to the pr~eviously-described preferred embodiment employing nozzle assembly 296, and hollow sleeve 800 and shut-off pin 834, to the aperture, slot or port 804 in sleeve 800 ~Fig.
50). Likewise, with regard to the preferred embodiment, the ~o7 -- ~o.s --term ~oeiice or layer B material~ refers to annular exit orifice 462, and the term "orifice for layer C material"
refers to annular exit ori~ice 502. It will be appreciated that equivalent pressure relationships will exist at equivalent orifices in othe-r embodiments of nozzles and no~zle valve means within t:he present invention such as, for example, those associated with sleeYe 620 lFig. 107), or with check valve 628 in flow pa~sageway 634 (~ig~ 108), or sliding valve member 638 and axial passageway 803 (Fig. 109).

At the beginning of the injection cycle, when the layer A material is flowing in the nozzle central channel 546 past the orifice for layer a material, the pressure of material B in the tapered melt pool 478 ~Fig. 50) in the nozzle just prior to unblocking the ori~ice for layer B
material, P(B)o, may be greater or equal or less than the pres~ure of the flowing stream of layer A material at the or~fice for the layer A material, P(A~). In practice, it i~
believed that P(B)o is greater than P(AA)o At the beginning of the i~jection cycle, when the layer A ~aterial i~ flowing in tbe nozzle ce~tral channel pa~t the orifice for l~yer ~ material, P(~)O should be equal to or greater than the average ratial pressure, P(A~), of the flowing s~ream of layer A material in the nozzle Gentral channel at the axial location in the nozzle central channel o~ the orifice for layer B material in order to prevent cros~ channel or back flow ~hen the orifice for layer B material i~ unblocked.

At the next step of the injection cycle, when both the layer A material and the layer B material are flowing in the nozzle central channel, the pressure of material C in tapered ~elt pool 518 just prior to unblocking the orifice for lay~er C material, P(C)O, should be at least equal to, and pre~erably is greater than, the average radial pressure, P~AC), of the ~lowing stream of layer A material in the nozzle central channel at the axial location in the nozzle central channel of the orifice ~or the layer C material.
PtC)o should be at least equal to P(AC) to prevent back ~0~

flow when the orifice for layer C material is unblocked. The ~elationship o~ P~C)O being preferably greater than P(AC) is important in the achievement o uniformity o location of the leading edge of the annular flowing stream of internal layer C ~aterial and, in turn, uniformity of location of the ter~inal end of layer C in the marginal end portion of ~he side wall of the injected article at substantially all locations around the circum~erence of the end portion at the conclusion of polymer ~lo~ in the injection cavity. P(C)O
should be greater than the pressura o~ the flowlng stream of layer B ~aterial as it enters the nozzle central channel at the orifice for layer B material, P(~B). P(C)O may be greater or egual or less than P(AA). It is believed that P(C)O is greater than P(AA). It i~ believed that in practLce~ P(C)O i-~ greater than P~B)~.

A~ a later 3tage o~ the injection cycle, when the injectlon cavity is partially filled with the melt ~aterials~
th2 pressure o th~ ~lowing strea~ of layer C material as it leav~ the orifice for layer C ~aterial, P(CC), is greater than P~AC), is less than P~AA), and is greater than the pres~ure o~ the flowing ~tream of layer C mat~rial in the nozzle central channel at the axial position in the noz21e cent~al channel of the orifice for layer ~ ~aterial, P(S~.
At this ~tage of the injection cycle, P(BB) is greater than P~AB), is le~s than P~AA) and is greater than P(CB). at the ~rue of the injection cavity, at this stage 'of the injection cycle, the pres~ures o~ the flowing strea~s of layer A
material, layer B material and layer C material are almost equal.

At a still later point in the injection cycle, when the flcws of the materials for layers A and C fro~ their respective orifices are being terminated, the pressure selation~hips are as follows. When the flow of material ~or layer A is terminated, and the materials for layers C and B
are still flowing, P(CC) is greater than ~he residual pressure of layer A Material remaining at the orifice for ~o~
- ~7 -.5~i'7 layer C material. This and the continuing flow of layer C
material into the nozzle central channel permit kni~ting of the layer C material to provide a continuous layer o material C at the sprue of the injected article. Next, when the flow of material for layer C is also terminated, and only the material for layer B is still flowing into the nozzle central channel, P(B~) is greater than the residual pressure of layer C material remaining adjacent the orifice for layer B material. This and tha continuing ~low o~ layer B material into the nozzle central channel permits knitting of the layer B material to provide encapsulation of layer C by layer B
material at the ~prue of the injected article.

The above-stated description of the pressure relationships among the flowing melt streams does not take into ac~ount small variations of pre~sure in the radial direction which may be present but ~hich are ~mall in comparison with variations of pressure in the axial direc~ion in the nozzle central channel. It does take into account the larger difference in radial pressure very close to the orifices of C and B required ~or these streams to enter the central chann~l, part`icularly when the knitting o~ the layer C and layer B materials is considered.

Fig. 129 i~ a plot of ~he melt pressure of each o~
the polymer flow streams A, B~ C, D and E in pounds per square inch as a function of time during a portion o~ an injection cycle o~ the eight-cavity machine previously described. The pressure was measured at pressure transducer port 2g7 in manifold extension 266, approximately thirty-nine inches away ~rom the tip of the nozzle (see Fig. 17). It should be noted that the pressures shown in Fig. 129 and Table IY are the pressures as measured approxlmately thirty-nine inches away from the nozzles and thus are not the pre~sures of the melt materials in the nozzles. ~owever, the pre~sures and pressure relationshlps of Fig. 129 and Table IV
do ~unc~ion to create the desired pressures and pressure relationship in the nozzle which are described above.

~(~

~ 7 Table IV gives the! pre3sure, in pounds per square inch, of each of the polymeric materials for layers A, B, C, D and E as a ~unction of ti,me in centiseconds of the injection cycle for the eight-cavity machine previously de~cribed~ Table IV was prepared from the information in Fig. 129.

TABLE IV
VARIATION OF PRESSURE
WITH TIME FOR T~E DIFF~RENT LAYERS

TIME PRESSURE IN PSI O~
(CENTISECONDS) A _ B C D & E

2400 2000 2800 16~0 3300 ~000 2800 1600 28 8000 ~8~0 1~0 : 40 G800 2800 4000 ~5 8000 680~ 6002 6000 . 8000 6300 8100 6~00 ~S ~200 6500 7800 6100 ' a300 6200 7650 ~000 115 870~ 7000 30~0 5800 1~5 9500 6800 1000 58~0 135 800~ 6400 8500 5700 ; 145 ~200 5000 6200 5000 165 3500 2700 270~ 2700 175 ~700 25~0 2000 ~2~i;62~57 TABLE IV
VARIATION OF PRE~SURE
WITH TIME FOR _~E DIFFERENT LAYERS ~Continued~

TIME PRESSU~E IN PSI O~
(CENTISECONDS) . ~ A B ~ C D & E
la5 2300 3Q00 3~0 1900 420 360~ 3600 1600 460 ~ 2R001600 ~65 ~0~0 2~00 280016~0 S~0 2~00 20~0 2~0016~

The temperature range wi~hin whiCh the ~elt ~trea~s of polymeric ~aterials are to be maintained in ac~orda~ce with thi~ in~ention ~111 vary depending upon ~arious actors such a~ the polymeric material-~ used, the cont iner3 to be formed and as will ~e explained th~ products they will contain. Utilizing the preferred ~aterials disclosed herein for forming the preferred five-layer containers for packaging most products including many food products, the polymeric materlals are preferably maintained at a temperature in the range o from about 400~. to about 490F.

Table V shows e~timations of the temperatures of each of t:he melt streams at different locations in the injectiorl molding apparatus of this invention during a typlcal run for forming multi-layer plastic containers for packaginy hot filled food products, and non-food products, based on the temperature settings of ambient structures through which the melt streams passed, from the extruders ~o the injection cavity sprues.
~12' ~5~2~i~

TABLE V

Layer Melt Material Temperature (FL~__ Apparatus Outer(B~ and Location Inner(A) _ Internal(C) Intermediate(D,E

Extruder Exit 490 + 10 430 + 10 450 ~ 10 Runner Block 435 ~ 5 435 + 5 435 + 5 Orifice Entrances to Combining Area of Co-injection Nozzles 450 1 15 430 + 15 440 + 15 Co-injection Nozzl~
- Injection Cavity Interface 460 ~ 15 440 ~ 15 450 ~ 15 ., . . _ ~_ .. . . ... _ . . .. . __ _ ~__ It ha~ been found that when certain polymeric materials such as certain polyethylen~s are ~rocessed at ~he higher temperatureR withiA the range, to form containers ~OE
packaging certain foods whlch require s~erilization processing at elevated temp2ratures, the materials may impart an off-~lavor taste to those food. ~or such applications it has been found that these ma~erials should be processed a lower temperatures, within the range rom about 400F. to about 450F.

It will be understood by those skilled in the art that processing conditions and the temperatures of structure~
of the ap3paratus may be adjusted to permit the use of such lower temperatures. An example of such an ad~ustment would be in rai~sing the temperature o~ the injection cavity tool set.
r ~ ?ig. 139 is a graph schematically plotting on the ordinate the melt flow rate of polymer material into an injection cavity as a function o~ time. The ascending dashed curve (4) lndicates polymer melt flow due to a linear ram displacement through a non-pressurized runner system which al3 ~5i6~5~

includes a nozzle passageway. The gradual increase of flow rate from zero is an indication of time response delay caused by the compressibility of polymer melt. The ascending solid curve (2) indicates polymer melt flow only due to ram displacement through a pressurized runner and nozzle passageway upon removal of blockage of the oriiice. ~n a~vantage of the pressurized flow system is that the tranqient response of the ~low curve due to ram displacement is aster ior a pressurized runner and nozzle passayeway than a non-pressurized runner and nozzle. An additional advantage is that an instantaneous flow oi polymer melt upon unblockage of the orifice will result (even the absence o~ further ram movement) from the decompressing of pol~mer melt in the runner and nozzle passageway, as indicated by the downwardly descending solid curve (1). The horizontal solid line (3) is the sum of polymer melt flow from decompression of polymer mel~ and ram diqplacement of a pressuri~ed runner and nozzle passageway. Thu~, Fig. 139 sho~s that in injection molding machines utilizing one or Dlore co-injection nozzles and having long runner systems ~ to achieve control over the polymer melt materials in terms of b~ing able to provide an in~tantaneous and relatively constant melt flow rate of any or all materials injected, physical means preferably operative in the nozzle central channel or preventing or blocking uncontrolled onset of flow from the no~zle orifice to the central channel should be employed with means removed ~rom the orifice for displacing the melt material, and ~or p~es3urizing the melt material.

In order to assure the achievement of an instantaneous, simultaneous, uniform high melt flow rate over all poinl:s of an or~flce in an injection nozzle with long polymer ilow stream passageways, either in the nozzle or in the runner or both, it is highly preferred that the ori~ice be blocked as by the valve means of this invention, and while the orifice is blocked, the polymer flow stream p~ssageway be pressuri2ed. Uniform initial ~low simultaneously over all ~oints oi the ori~ice is then achieved by merely unblocking y ~2~6~5~

the orifice. Preferably ho~ever, the means ~or displacing the polymer material in the passageway is used to additionally pressurize the material in the passageway just before or upon unblocking oi. the orifice. This achieves a high pressure level as the material initially flows through the orifice. If it i3 then desired to further control the flow of the material to achieve and maintain a relatively constant melt flow rate during the inj~ction cycle, the pol~mer material in the passageway should continue to be displaced by the displacement means during the injection cycle.

The relationships which determine the specific requirements for residual pressure and for ram movements will now be described in greater detail. As has been described previously, it i~ necessary that the level o prepressurization at the orifice for the C layer material be at least slightly higher than the a~bient pressure at all circumferential locations a~out the ~lowing material to acbieve inYtantaneous flsw through ~he orifice. This prepressurization, even in the absence of further ram movement, would supply polymer for flow through the decompression o~ the polymer m~lt in the tapered conical section, in the rest of its nozzle passageway, and 1n the rest of the runner system~ The compressed polymer nearest the orifice will have a more immediate e$ect on the polymer flow than will the more remote polymer. It should be appreciated, however, that even a very small amount of flow will considerably decompress this polymer melt and reduce its pressure.

Fig. 139A shows the precsure history at the ori~ice or a simplified case in which there is no ram movement and no flow of other materials in the nozzle central channel. ~9 soon as the orifice opens, there is flow from the orifice and the pressure starts falling. When the pressure reaches the ambient pressure (here, zero~, melt flow cease~. When the orifice is closed and screw recharge is actuated (screw moved ~s~

forward), the melt pressu3:e rises in the runner system and at the orifice, and, assuming suf~icient time is allowed, eventually reaches a level equal to that in front o~ the screw. This residual pressure remains until it is released in the next injection cyc]Le.

Fig. 139B shows the ambient pressure within the central channel, at the closed C orifice, due to a steady flow of the A and B polymer melt materials. The pressure rises from zero, initially quite rapidly ae the melt flow is established, and gradually increases as the injection cavity is filled and the total resistance to flow increases. This Figure also shows that at some point in time the ambient flow is stopped and the valve means clears the melt from the central ch~nnel, at which point the pressure is again zero.

Fig. 139C shows the pressure in the C orifice for a simplified case in whiGh there is prepressurization and in which there is ambient pressure ln the combining area of t~e nozzle from flow of all polymers, but in which there is no movement of the ram which moves the polymer C layer material. A~ain, as in Fig. 139A, there will be an initial and spontaneous flow of polymer C layer material as soon as the orifice is unblocked, but the flow will rapidly diminish and cease as the C layer material is partially decompressed by its own flow. This initial flow of C layer material will be very light and tAe resulting C layer will be extremely thin in the injected article if the prepressurization level is only slightly higher than the ambient pressure at the time of unblocking.

Fig. 139D shows a case in which there is prepressuri2ation, ambient flow, and ram movement, but in which the ram movement is initiated somewhat after the orifice is opened. There will be an initial spontaneous flow of polymer C and thPre will be substantial later flow of polymer C, but there will be an intermediate time, shown in the Figure as the two pressure curve~ approach each other, in alb 3L~56~;'7 ~hich there will be DO or an insubstantial flow of polymer C-Fig. 139E shows the same case as in Fig. 139D~
except that ram movement is started somewhat before the orifice is opened~ In Case (a), ram movement is relatively gradual such that by the time the ~ajor pressure response to the ram movement reaches the orifice, the C orifice has just opened and the initial drop in pressure seen in Fig. 139D is prevented. In Case ~b~, ram movement i~ initially very rapid so that by the time the orifice is opened, the melt pressure in the orifice is considerably higher than khe residual pressure. As can be seen in Case (b~, the pressurization of the C layer material, that is, the pressure difference between the pressure in the C orifice and the ambient pressure in the central channel is nearly constant, thereby resulting in a more uniform flow and a greater more constant thickness of C throughout the injection cycle. Case (c) is like Case (a) but it illustrates that a slight preS-Qure above the ambient pressure is sufficiant to cause flow. With r~spect to Case (c), the pressure difference at the time o~
opening o~ the orifice i~ relatively ~mall, this could have been miti~ated by a higher initial pressure level or by an earlier commencement of the gradual ram movemen~.

It should be appreciated that Figs. 139A through 139E are schematic and that certain portions have been exaggerated to show more clearly slight, but important differances in pressuresn The previous paragraphs describe one of the advantages of a high level of prepressurization; that is, to provide spontaneous flow upon unblocking the orificeO It was further described how the initial level of p~epressurization, the residual pressure, was preferably combined with a movement of the flow displacement means, the ram~ to generate an additional pressure near the orifice prior to or simultaneously with the unblocking of the orifice. There will no~ more fully be described an additional advantage of .

~ 2~

pressurization; that i9~ shortening the time response of the polymer near the orifice to a movement of the ramO

A rapid response time is of great importance to the achievement of the pre~erred articles of this invention; that is, of multi-layer articles in which a relatively thin buried layer e~tends uniformly into the marginal end portion or flange and in which the bur:Led layer does not become excessively thin at any location. As was described previously and illustrated in Fig. 139E, a rapid pressure rise aq a result of a ram movement i~ de~ired near the orifice of C in order to compensate for the rapid pressure drop which results from unblocking the orifice. If the time response is too slow, even a very rapid move~ent of the ram ~ill result only in a very gradual rise in the pre sure at th~ opposite end of the runner. For that reason, it has been found difficult to dsvelop the desired rate of pressure rise because of the length of the runner systems present in multi-coinjectisn nozzle injection molding ~achine-, and becau~e of the high compressibility of the material in the ~unner system. It shall ~irst bs described how the geo~etry of the runner ystem affects the response ti~e and then the effect of fluid co~pressibility will be describe~.

- The runner ~ystem of a balanced multi-cavity system is necessarily vsry long to reach from a re~ote poly~er displacement means to each of several nozzles. The ~act that the multi-cavity nozzles of this invention are designed to provide a balanced flow of extremely thin layers aggravates the time response problem in that the nozzles are relatively rastricti~e to the ready flow of material. In particular, the presence of chokes, of the converging conical section~, and o~ the geometLi~al restrictions imposed by the flow channels of the other layers tend to result in restricted flow. These res~rictions tend to isolate the key portion o~
the flow passageway, i.e., the ori~ice, from the greater volu~e of the rest of the runner system. This makes ~he nozzle orifice section relatively unresponsive to the - ~6 -pres~ur~ in the mass of the runner system, whether that pressure is in the form of a relatively static pressure through prepressuri~ation or of a dynamic pressure being g nerated by ram movement.

It should also be noted that the co-iniection nozzles of this invention may not be completely balanced with respect to time response. That is, the ~ateriaL entering ~rom the rear oS the nozzle shell enters a ~elt pool at one location which will have a quicker time response than will the location in the melt pool 1~0 ~rom the entry point. As a result of this i~balance, the preRsure rise may be faster at one circumferential location of ths orifice than it will at another. The effect of such an imbalance would be minimi2ed if the overall respo~se of the ~ystem would be fa~ter.

The effect of compres~ibility on the time response of the cunner system will now be described. ~he response ti~ of a compres3ible vi3cou~ ~luid within a closed chan~el or pas~ageway can be defined a~ the time required to reach a given pressure as the re-~ult of a change in pressur~ at the oppo ite end o~ the fluid flow ~hannel. ~or a given ~luid within a specific channel, the time response is direc~ly related to the compressibility of the fluid. Compressibility is de~ined as the fractional decrease in unit volu~e as a ~unction of a one p9i increase ln hydro~ta~ic pressure.
~igure 139F shows the compressibility of high density polyethylene at a temperature o~ about 400F. as a function of p~essure over the range of zero to 14000 psig. ~igh density polyethylene is a material which may be utilized in formlllg some layers of the articles of this invention.
O~her poly~er melts utilized herein will have similar cur~es. It is particularly significant that the compressibili~y is much higher at low pressures than it is at higher pressures. The compressibility at a~mospheric pre~sure is 13.2xlO 6(psi)-1 while at 8000 psi it is only 6.5xlO 6l,psi) 1. This means that a polymer melt of a ~ 7 -~2~

material such as polyethylene will raspond con~iderably faster to a given ram displacement if the melt within the runner sy~tem is already partially compressed. Stated differently, if one is compr~ssing a polymer melt in a runner from atmospheric pressurè to a very high pressure level, the initial por~ion of the pressurization will be considerably slower than the final portion.

By ~he pre~erred method of this invention the initial, slow pressurization is effected as early as possible in order for the entire runner system to be at the partially elevated pressure before that portion o~ the cycle in which rapid response is most critical. In particular, the initial pressurization occurs as soon as the valve means have closed following the previous injection. The level to which the system is pressurized at this early time may be limited, as has been di~cussed previously, by mechanical considerations such as leakage and breakage as well as by the possibility ~f obtaining exces~ive flow of the bu~ied layer as soon as the orifics is unblocked.

The ~ollowing will explain a method of this invention utilized for prepressurizing the runner system, ~hich is h~rein meant to include the feed block and passageways in the nozzle assembly. At the end of an inje~tion cycle when the ram is at its lowest volume, while the orifices in the co-injection noz~le are blocked by the valve means, a forward movement of the reciprocating screw in the extruder i~ initiated to provide material to and to pressurize the ram and runner system. Shortly before or shortly thereafter, the ram is retracted upward to increase the volume o the runner systemO As the rams move upward, the pres~ure in the system tends to drop while the extruders are filling the expanded volume with polymeric melt mat rial. When the rate of volume expansion in the ram equals thle rate of melt replacement, tAe pressure in the ram runner system tends to remain substantially uniform.
~owever, usually, the ram volume increases a~ a rate faster 5;7 than the melt replacement rate and the pressure therefore tends to decrease. Given this dynamic system, there tends to be a pressure distribution or variation throughout the runner system with the lowest pressure usually being adjacent the ram plunger ~ace and the highest pressure near the extruaer nozzle. When the ram retract~ to its furthest point and stops, the extruder continues to move melt material forward into the runner system. As it does the pressure increase~.
Once the extruder stops pushing material into the system, and the check valve prevents back flow of material toward the e~truder, the pressure in the runner system, at this point, will have a distribution or profile which, given sufficient time, will equilibrata or become substantially uniform throughout. This amount of pressure in the systemt whether it be non-uniform or substantially uniform, is herein referred to a~ the rech~rge pressure, baseline pressure or residual pr~ssure. Thus, the residual pressure measurements will vary depending on where the measurement is taken in the system and when the measurement is taken. In accordance with the methods of this invention, the residual pressure employed i~ the runner system o~ the preferred apparatus of this invention is pre~erably from about 1000 psi to about 5000 psi, more preferably from about 2000 to 4000 psi. Wi~h this apparatus ~ Yome slow leakage may tend to begin to occur at some pressure above 4000 p~io In accordance with the above, pre~erred methods for prepressurization practiced in accordance with this invention involve imparting to the polymer melt material in the runner system while the orifice is blocked by the valve means, a pres-~ure greater than the ambient pressure in the system.
Although the pressure imparted can be the residual pressure, preferably the level of pressure is greater than the residual pressure. The pressure is imparted by the means for displacing or movin~ the polymer material through the runner system. This can be a screw, or a reciprocating device such as a screw or ram. In this invention, the preferred means are the rams. The ram is moved forward to compress the melt -- 2~9 -'7 and increase the pressure of the melt in the runner system including the nozzle passageway and itq orifice. Subjecting a polymer melt material in the runner system, particularly in the passageway and at the blocked orifice, to any pressure greater than the residual pressure in the system can be referred to as further prepressuriziny of the material.
Further prepressurization can be effected prior to reaching equalization of the residual pressure in the system. It should be noted that the measured or discerned level of residual pre~sure can be either less than equilibrium or greater than equilibrium depending on where and when the measurement is e~fected. It is preferred to obtain as high as possible an average r~sidual pressure without causing leakage of the material past the valve means into the central channel and without damaging the nozzle shell cones, particularly their tips, or damaging the plurality of seals throughout the system. The amount of further prepressuri2ation will vary but it ~hould be at a level ~ufficient to provide a rapid, or substa~tially simultaneou uniform initial onset flow over all points of the ori~ice, that is, one which will substantially reduce the tim~ bias o~
the leading edge of the internal layer or layers in the marginal end portion of the container. It is particularly preferred that the prepressurization be at a level which is greater than that required to cause the polymer melt material in a passageway to flow spontaneously into the central channel once its orifice is unblocked, and that it be at a pressure which will create, whe~ the orifice is unblocked, a sufficient surge of material over all points of the ori4ice into the central channel when the flow s~ream is con~idered relative to a plane perpendicular to the axis of the central channel. Pre~erably, the level of inltial prepressurization is at least about 20~ or more greater than the ambient pressure, or, than the level of presqurization necessary to cause the polymer melt material to flow into the central channel once the orifice is unblocked. The p~epressurization level desirably is sufficient to densify the material in the passageway adjacent the orifice to a density of from about 2 ~a ~5~

to about 5% or more greater than atmo~pheric den~ity. As previously stated, the amount of pressure sufficient to cause the material to flow into the central channel is greater than the ambient pressure of the already flowing materials in the central channel ~See Fig. 139E).

It is also preferred that the level of prepre~surization i sufficient to overcome any non-uni~ormities in low due to imper~ections in the uniformity and the symmetry of the design~ of the structure of ~he passage~ay orifice. The advantages of prepressurizatio~ are increasingly significant in multi-coinjection nozzle injection molding machines in that the advantages in overcoming temperature variations and other variation~, for example, within tolerances due to machining are increased and a~e more significant relative to obtaining inj~cted article~ from one co~injection noz~le having the same or substantially the same characteristics as the injected articles from each of the other co-injection noz21es. With the preferred methods of prepressurizing a polymer stream, particularly that o~ the internal layer material~s), a~ the prepressurized blocked orifice is being unblocked by movement of the ~alve means, th*re is included the step of changing the rate of ~ove~ent o~ the di~placement mea~s, for example, by increasin~ the rate of displacement o~
~he ram, to attempt ~o achieve or approach and maintain a substantially ~teady 10w rate of the material through the orifice into the central chanrel. Preferably, the steady flow rate is the desired design flow rate, and pre~erably the subsequent pressure is maintained for from about 10 to about 80 preferably to about 40 centiseconds at a pressure level sufficient to provide and maintain a uniform thickneqs about and along the annulus of the material flowing rom the orifi~e.

This invention includes methods of initiating ~he flow of a melt stream of pol~meric material substantially simultaneously from all portions of an annular passageway _ ~. _ orifice into the central channel of a multi-material co injection nozzle, compri:sing, providing a polymeric melt material in the passageway while preventing the material rom flowing throu~h the orifice into the central channal ~preferably with physical means such as the valve means of this invention), flowing a melt stream of one or more polymeric material(s) through the central channel past the orifice, subjecting the melt matarial in the passageway to pressure which at all points about the orifice is greater than the ambient pressure of the flowing stream at circumferential positons which correspond to the points about the orifice, the pressure being sufficient to obtain a simultaneouq onset flow of the pressurized melt material from all portions of the annular orifice, and, allowing the pre~surized material to flow through the orifice to obtain said simultaneous onset flow.

This invention also includes methods of initiating a substantially simultaneous flo~ of a polym~ric melt material which ~ill form an internal layer of a multi-layer injection molded article, from an annular pas-qageway orifice 5uch that the internal layer mat~rial surrounds another polymeric melt material stream al~eady flowing in the central channel, wherein the co-injection nozzle is part of ~
multi-coi~jection nozzle, multi-polymer injection mold~ng machine having a runner system for polymeric melt ~ateri~ls which extends from ~ources of pol~meric material displacement to the orifice~ of the co-injection nozzle, comprising, blocking an annular orifice with physical means, and while so blocking the ori'ice, moving polymeric melt material into the runner system, and while flowing polymeric melt material through the central channel past the blocked orifice, subiectinsl the polymeric melt material in the runner system to the pressure which at all points about ~he blocked orifice i5 greater. than the ambient pressure of the flowing melt material stream at circum~erential points which correspond to said point:s about the orifice, wherein the pressure is sufficient: to obtain the substantially simultaneous onset - 2~ -~L~5Çi;?i~7 flow, and unblocking the orifice to obtain saidl flow into the central channel. With respect to the aforementioned methods of initiating substantially simultaneous flows, preferably, the material pressurized is that which will form the internal layer of a multi-layer article injectea from the nozzle, the subjected pressure is uni~Eorm at all points about the orifice, and the orifice has a center line which is substantially perpendicular to the axis of .the central channelO ~uring the allowing step there i5 preferably included the step of cont:inuing to sub~ect the material in the passageway to a pressure sufficient to establish and maintain a substantially uniform and continuous teady flow rate of material simultaneously over all points of the orifice into the central channel. The subjected pressure ls suffieien~ to provide the onset 10w of the internal layer material with a leading edge sufficiently thick at every point about its annulus that the inte~nal layer in the marginal end portion of the side wall of the article formed is at l~as~ 1~ of the total thickness of the ~ide wall at the m~rginal end portion. In pressurizing the runner system, the pre3sure ~ubjecting step i~ preferably effected in two stages, first by providing a residual pressure lower than the desired pressure at which the material is to flow through the blocked orifice to increase the time response of the polymer ~elt material in the runner ~ys~em to subseguent movements of the source of polymeric melt material displacement means, and then befoYe or upon effecting the allowing step, raising the le~el of pressure to the desired pressure at which the internal layer material is to flow through the orifice. The pressure raising ~tep may be executed gradually but preferably rapidly, just prior to or upon effecting the allowing ~tep. A polymer supply source exterior of the runner system such as a reciprocating screw upstream of a check valve can be employed to pressurize the polymeric material in the runner system. In the two stage pressurizing method, the providing of the residual pressure can be effectedl by reciprocatlng the source of polymer melt material displacement.

This invention includes methods of prepressurizing the runner sy~tem of a unit-cavity or multi-cavity multi-polymer injection molding machine for ~orming injection molded articles, having a runner ~ystem for polymQr melt materials which e~tends from sources of polymer melt material displacement to the orifice~ of a co-injection nozzle having polymer melt material passageways in communication with the orifices which, ~n turn, communicate with a central channel in the nozzle, which in so~le ~mbodiments baqically comprise~, blocking an orifice with phy ical mean~ to prevent material in the passageway of the orifice from flowing into the central channel, and, while so blocking the orifice, retrac~ing the polymer melt material displacement means, filling the resulting volume in the runner system with polym~r melt material from a source upstream relative to the polymer melt material displacement means and external to the runner system, the amou~t of retraction and the pressure of the polymer melt with which the ~olume is ~illed being calculated to be just sufficient to pro~ide that layer'~
po~tion o~ the next injection ~olded article and th~ pre~ur~
of the ~olume-filling melt being de~igned to generate in the runner system a residual pras~ure suficient to inereas~ the time response of th~ polymer melt material in the runner ~yskem to sub e~uent movement~ of the source of polymer melt material di3placement meanq, and prior to unblo~king th~
orifice, displacing the polymer melt material displacement means towards the orifice to co~press the material furth~r and raise the pressuxe in the runner system to a level greater than the residual pressure and sufficient to cause when the orifice i3 unblocked, the simultaneous onset flow.
These methods can al30 be effected while the orifice is blocked, ~y moving melt material into the portion of the runner system extending to the blocked orifice, discerning the level of re~idual pres ure of the polymer melt material moved into said portion of the runner sy~tem~ and di placing the melt material in the runner system towards the orifice to compres~ the material and raise the pressure in the runner sy~tem to a level greater than the residual pressure and ~2~G
~4 ~56?.b.~ ;

sufficient to cause the simultaneous and preferably uniformly thick onset flow.

This in~antion also includes other methods o~
effecting prepressurization. The invention includes a method of prepressurizing the runner system for a polymer melt material of a multi cavity multi polymer injection molding machine, which extends from a source of pol~mer melt material displacement to the orifice of a co-injection nozzle having a polymer ~elt material passageway in communication with the orifice which in turn communicate with a central channel in the nozzle, which comprises, blocking the orifice with physical means to prevent polymer melt material in the passageway of the orifice from flowing into the central channel, and, while so blocking the orifices, moving ~olymer melt material into the runner sy tem, di-~cerning the level of r~Qidual pressure of the polymer melt material moved into the runn~r system, and displacing at the polymer melt material in the runner system toward its blocked orifice to ¢ompress the material and raise the pressure in the runner system to a level greater than the residual pres~ure and which is 3u~ficient to cause, when the ori~ice is unblocked, a ~imult~neous and uniformly thick onset flow of the prepre~surize~ polymer melt material over all points of ~he orifice into the central channel. This method can be employed for any or all of the melt materials supplied to a co-injection nozzle, or to a plurality of co-injection nozzles of a multi-cavity multi-polymer injection molding machine.

Other prepressurization methods are those o~ ~orming a multi-layer plastic article with a marginal end portion, an outer surface layer, and an inner surface layer and at least one internal layer therebetween, such that the leading edge of the internal layer extends substantially uniformly into and about the marginal end portioll of the article or container, wherein the method comprises the same steps as the prepressurization methods of this invention relating to ~7 ~L25~iZ~7 extending the leading edge of the internal layer uniformly into ~he ~arginal end portion of an article or pariso~ or container having a side wal.l.

Another method of prepressurization of this invention is that o forming an open-ended, five layer plastic article having a side wall with a marginal end ~ortion, an outer surface layer, an inner surface layer, an in~ernal layer, and an inter~ediate layer between the internal layer and each urface layer in an injection cavity of a multi-cavity multi-polymer injection molding machine such that the lead~ng edge of the internal layer extends substantially uniformly into and about the marginal end portion, wherein the multi-cavity injection molding machine has a runner system which extends from ~ources o~ polymer melt material displacement to a co-injection nozzle having a polymer melt matesial flow passageway for each material which is to form a layer of the article, a central channel, and an orifice for each pa~sageway in communication ~ith it5 pa~sageway and the central channel, mean~ for di~placing the poly~er ~elt mater~als to the orifices and into t~e central channel of the co-injection no~zle, there being a displacing means for each material which ls to orm a layer of the article, ~2ans for providin~ polymeric melt materials into the runner system, and physic~l mean~ for blocking and unblocking the orifices, which comprises, blocking at least the orifice~ for the materials which are to form the internal and inter~ediate layers, with physical means to prevent said materials from flowing through their blocked ori ice~ into the central channel, moving polymer melt material into the runner ~ystem, discerning the level of re idual pressure of the polymer melt material-~ that have been moved into the runner system, displacing the polymer melt materials for .
forming the internal layer and the intermediate layers in their pas~ageways towards their blocked orifices to compre~s the materials and raise the pressure in the system for those materials to a level greater than the residual pressure and suicient to cause uniform and simultaneous onset ~low of.

- ~6 -'7 each said prepre3surized layer materials over all points of their orifices into the central channe} when their orifices are unblocked, flowing the inner surface layer material into and through the central channel while preventing the flow of the internal and intermediate layer materials into the central channel, flowing the outer surface layer material through the cen~ral channel in the form o~ an annular flow stream about the flo~ing stream of inner surface layer material, unblocking the orifices of the prepressurized internal and intermediate layer material~, flowing the prepressurized ~nternal and intermediate layer ma~erials into the central channel into or onto the inter~ace o~ the flowing inner and outer surface material such that the internal layer material and the intermediate layer materials respectively have a rapid initial and simultaneous onset flow over all points o~ their respective orifices into the central channel and each orms an annulus about the flowing inner surface layer material between it and the outer surface layer material, and such that the leading edges of the respective annulusas o the internal layer ~aterial and the intermediate layer mate~ials each lie in a plane substantially perpendicular to the axis of the central channel, and, injecting the combined flow stream of the inner, outer, internal layer ~aterials into the injection cavity, in a manner ~hat renders said leading edges substantially uniformly into and about the ~arginal end portions of the container.

Another method included within the scope of this invention for initiating a substantially uniform onset flow of one or more melt material stream of polymeric materials into tAe central channel of a nozzle of an injection molding machine for forming one or more internal layer~ of a multi-layer plastic article injected from the nozzle and having an outer surface layer, an inner surface layer and one or more internal layers therebetween, comprises utilizing one or more condensed phase polymeric materials as the one or more inte!enal layer melt stream or ~treams of polymeric t~

material(s), flowing the inner layer melt stream into the central channel as a core stream E~ast said at least one orifice, flowing the outer layer~melt stream into the central channel to surround the already flowing core stream, providing the combine.d flowing streams for the outer and inner layers with a select:ed ambient pre~sure in the central channel, supplying said one or more internal layer melt streams of condensed polymeric material into their passageways, imparting a s~elected first pressure to each of ~aid one or more internal layer melt streams at said at least one orifice, said first pressure being below that pressure which, relative to the ambient pressure, would cause the material(s) or the internal layer(s) to flow into the central chann~l, adjusting the first pressure to a second level equal to or just below the ambient pressure of the materials flowing in the central channel to compress the one or more internal layer melt 3treams to provide a flow response into the central channel which would be more rapid than ~ithout ~aid adJusted first pre~sure, and to prevent back flow o~ alre~dy flowing material into the at least one internal orifice, and causing the internal layer melt stream or ~treams to flow rapidly through the at lea~t one orific2 into the central channel, by creating a rapid change in the relative pressures between the one or more internal layer materials at sa~d at least one orifice and the ambient pressure in the central channel, such that the pre sure of the one or more internal layer ~aterial~s) is rapidly changed to a level suficiently high relative to the am;bient pressure that there i8 established a substantially unifor~ onset flow o~ said one or more internal laver material(s) as one or more annular Rtreams substantially imultaneously over all points of said at least one orifice into the central channel. Xn the a~orementioned method, the rapid change in relative pressures can be effected by rapidly increasing the pressure of the one or more internal layer materials, or by decreasin~
the ambient pressure of the already flowing streams in the central channel, or by a combination of both. This method is applicable to forming five layer articles wherein three z~3 ~

~2~ '7 internal layers are injected, for example an internal barrier layer having to either of its sides an intermediate adherent layer.

A ~condensed phase~ material here means a material in which there is no signiicant gaseous or vapor phase when the material is subjected to atmospheric pressure or higher.
A material containing an incidental quan ity of dissolved water i~ herein considered lo be a condensed phase mat~rial, even though dis~olved water in su~ficient amounts may foam somewhat at elevated temperatures and pressures. Foaming would be undesirable~ It is to be noted that in the processes of thi~ invention, no foaming has been observed.
Condensed phase material~ are relatively incompressible compared to mixtures or solutions used to make foams, and they have a ~ea urable and substantive change o~ density with the high pressure levels used in injection proce~es.

Another method of initiating a ~ubstantially uniform flow of a melt stream material over all points of an annular ~nternal passageway orifice into a central channel of a multi-material co-injection nozzle to form an internal laye~
of a multi-layer injected article involves preventing the internal layer from flowing through its orifice, pressu~ixing the material in the passageway while ~ontinuing to prevent its flow, said pressurization being sufficient to pro~ide a pressure in the internal layer material which is greater than the ambient pressure in the nozzle central channel and greate~ than the pressure being imparted to the flowing other material, and said pressurization further being sufficient to densify the internal layer material in the passageway adjacent ~he orifice and to create a high initial rate of flow of internal layer material simultaneously and uniformly through all points around the passageway ori~ice when the material is permitted to flow therethrough, and permitting said pressurized internal layer material to flow through qaid orifice in said simultaneous and uniform initial manner.
This method can be utilized with respect to forming a three ;

2~!

~,5~2~7 o: five layer material wherein the Lnternal layer material surround~ a ~tream of another melt material already flowing in the central channel and the level of pressure is sufficient to cause the internal layer material to insert itself annularly about the already flowing material from the third nozzle orifice, usualLy the A layer mat~rial, to provide a combined stream which includes a substantially concentric and radially uni;Eorm core of material from the third orifice, a next surrounding uniform, ubstantially concentric layer of materia:L from the second orifice, usually the C layer material, and ~urrounding that material, an encomp~ssing uniform, substantially concentric layer of material flowing from the first orifice. Preferably this method is effected with tapered pa sageways for increasing the volume of compressed material adjacent the orifice which w~ll initially flow into the central channel when the orifice i~ unblocked. P~efera~ly the pressure on the internal layer ~aterial is from about 20~ or more higher than the ambient pre3sure of the already flowing materials in the centgal channal. An additional pressure can be imparted upon the internal layer ~aterial once ~t is allowed to flow to maintain an effective total~pres~ure sufficient to approach and maintain a sub~tantially steady flow rate of the ~terial through the second orifice into the channel. It is advantageous that the internal layer passageway be tapered toward its orifice to increase the volume of ~ompressed ~aterial adjacent tha orifice which will initially flow when the orifice i~ unblocked, relative to an untapered passage~ay having an oriSice of the same dimensions.

Still another method of effecting a substantially uniform on~et flow ~imultanaously over all portions of an annular passageway lncludes imparting a first pressure which is in~ufficient to caus~ leakage of the condensed pha e materials through the blocked orifices into the central channel or from one orifice into another orifice, yet which would be sufficient to cause the materials to flow into the central channel if their flows were not prevented or their ~ ~ ~

~5~57 ori~ices were unblocked, and, prior to allowing them to flow through the passageway orifices, separately and independently sub~ecting the materials in the passageways to a second preRsure greater than the .Eirst pre ~ure and su~icient to create, when their orifices are unblockedr a surge of said polymeric materials and un:iform onset annular flows thereo~
into the central channel when the leading edg~s of the respective flow streams ar~a considered relative to planes perpendicular to the axis of the,central channel, said second pressure b~ing of a sufficiLent level and being imparted for a duration ~ufficient to establish and maintai~ the substantially uniform initial flows simultaneously over all points of the orifices into the central channel.

Another method of this invention is that of ~orming in a co-injection ~ozzle a multi-layer ~ubstantially concentric combined stream of at lea~t three polymeric materials, which includes utilizing valve maans in the cen ral channel operativa adjacent the orifices to block and unbloc~ the second orifice and to ~revent and to allow the flo~ of internal poly~er material through the second orifîce and for independently controlling ~hç ~low or non-flow of the core material thraugh the third orl~ice, preventing flow of polymer material from all of the orifices, continuing to prevent flow of polymer material tbrough the second orifice while allowing flow of s~ructural ma erial through one or both of the irst and third ori~ices, then, subjecting the polymer material in the second passageway to a fir~ pressure which would be sufficient to cau~e the material to ~low into the cent~al channel if its orifice was unblocked, prior to allowing flow through the second passageway, subjecting said material ln the ~econd passageway to a second pressure greater than the flrst pressure yet less than that which would cau~e leakage o~ polymer material through the orifice past the blocking valve means into the channel, said second pressure being sufficient to creata when said orifice is unblocked, a surge of polymer material and a uniform onset annular f,low of polymer material into the central channel ~33 ~;i6~'7 when the flow ~tream i9 considered relative to a plane perpendicular to the axis of the central channel, increasing the rate of movement of said polymer mat~rial to approach and maintain a substantially steady flow rate of ~aid material through the second orifice into said rhannel, preventing the flow of polymer material t;hrough the third orifice while allowing the second pressurized flow o material through the second orifice, to knit the intermediate layer material with itself through the core material, preventing the flow of polymer material through the second orifice while allowing flow of polymer material through the fir~ orifice and, either moving the valve mean~ forward to push the knit intermediate layer fo-ward and to substantially encapsulate the knit internal layer with material from the first orifice, or, accumulating material that has flowed from the third orifice at the forward end of the valve means, and moving the ~al~e ~eans forward to substantially encapsulate the knit intermediate layer material with the accumulated material from the third orifice.

The above method can include the steps of subjecting ~aid material in the first passageway to a second pre~sure greater than the first pressur2 and sufficient to cre~te when its orifice is unblocked, a sur~e of poly~er material and a uniform onset annular flo~ of polymer material into the central channel when the flow stream is considered relative to a plane perpendicular to the axis o~ the central channel, said second pressure being less than that which would c~use leakage of polymer material past the blocking valve means into the channel, allowing the flow of material through the first orifice, and increasing the rate of ~aid forward movement of qaid polymer movement mean to attempt to achieve and maintain 2 substantially steady flow rate of said material through the first orifice into ~aid channel.

The above method can further include the steps of, prior to allowing the flow of core structural material through the third orifice for forming the inner layer of the ~3 - 2~ -article, subjecting ~aid materlal in the third passageway to a second pressure greater than the first pressure and sufficient to prevent any detrimental pressure drop when its orifice is unblocked, and upon unblocking of the orifice, to create an i~mediate ~low response of polymer material into the central channel, said second pressure being less than that which would cause leakage of polymer material past the blocking valve means into t:he chann21, allowing the flow o~
material through the third orifice~ and modigying the rate of aid forward movement of said polymer movement means to maintain a modified substantially steady flow rate of said material through the third ori~ice into sald channel.

Another method of this invention is that of fvrming in a co-injection nozzle a multi-layer sub~tantially concentric combined stream of at least three polymeric materials for inje¢tion as a combined tream into a cavity to form a multi-layer article, the combined stream having an outer layer of structural material ~or forming the outer layer of the article, a core of structural material for forming the inner layer o the article, and one or ~ore intermediate layer (3) of material for forming an internal layer~s) o~ the article, which comprises, providing the co-injection nozz]Le means of tAis invention having at least threa polymer low 3tream pa~sageways and orifices, valve ~eans operative in the nozzle central channel a~d a source of palymer moveme~t for each polymer ~aterial which is to form a 1 yer of the structure to move each said material to i~s passageway and its orifice in the co-iniection nozzle, preventing flow of polymer material from all of the orifices, continuing to prevent flow of polymer material through the second or:iice while allowing flow of structural material through one or both of the first and third orifices, then, prior to allowing flow through the second passageway, ~ubjectin5~ said material in the second passageway to a pressure :Less than that which would cause leakage of polymer material pa~t the blocking valve means into the channel, and yct sufficient to create when its orifice is unblocked, a 3f ~urge o~ polymiar material and a uni:Eorm 0~8et annular flow of poly~er material into the ceantral channel when the flow strec~m is considered relative to a plane perpendicular to the axis o~ ths central channel, allowing said surge and uniform onset flow of intermadiate :layer material t~rough the second orifice~ maintalning a pressure on ~aid polymer material sufficient to approach and maintain a substantially steady flow rate o~ aid material through the second orifice into said channel, preventing the flow of polymer ma erial through the third orifice while allowing the secand pressurized flow of material through the second orifice, to knit the intermediate layer material with it~elf through the core material, preventiny the ~low of polymer material through the second orifice while allowing ~lo~ o~ polymer material through the ~irst orifice and, either moving the valve means ~orward to push the knit intermediate layer forward and to substantially encapsuLate the knit internal laysr with ~aterial from the first ori~ice, or, accumulating material that ha~ flowe~ from the third orifice at the forward end of the ~al~e m~an~, and moving the valve mean~ forward tG
~ub~tantially encapsulate the knit intermediate layer material with ~he accu~ulated material from the third orifice~ -~ nother method of forming in a co-injection nozzle a multi-layer ~ubstantially concentric combined stream of at least three polym~ric materials in the aforementio~ed co-injection nozzle means involves controlling the thickness, uniformity and radial po-~ition of the internal layer in the combined stream by pro~iding and utilizing means in all annular polymer flow stream passageways at least in the fir5t and ~econd passageways ~or balancing the flow of the respective polymer ~low strea~s passing through the first and second passageways such that, as the respective ~treams enter the central channel, each Elow ~tream is substantially uniform in terms of pressure and temperature about its circumference ~uch that in the combining area of the nozzle, each of the respective layers which form the combined stream are ~ub~tantially concentric relative to each other.
~b ~s~

Preferably the core structural ~aterial i-~ concentri~
rolati~e to the axis o~ the central chann~l when the material for for~ing the outer layer o the article is int~o~uced lnto the centraL chann~l, and prefeEably both the core material and the out~r layer material are substantially conce~tric and have their midpoi~ts substantia}ly on the axis o~ the central channel ~hen the internal Layer is introduced between them in the combining area of the ~entral channel.

~ t another method o forming in a co-injection nozzle a multi~layer sub~tantially co~c~ntric combined stream o the at least three polymeric mate~ials for injection in o a cavity to form a multi-layer article, wherein the article ha one or mo~e intermediate layers o~ mat~rial for forming an interna~ layer of the article, compri~es, providing the co-injection nozzle ~ean~ o~ ~his inventioA having at lea~t three ~olymer ~elt flo~ stream pa sageways and orifices and, utilizing valve mean~ operative in the nozzle c~nt~al channel fo~ blocking the ~i~ t an~ second ori~ices, subjecti~g the poly~e~ ~a~erials in ~he pa~sageways bloc~ed by said valve mean~ to a ~ir~t pressur~ suf~icient to cau~e the blocked material~ to flow into the central rhannel if the valYe ~eans ~e~e not blocking the first and ~econd orifices, subjecting the ~at~al~ in the pa~sageway3 to a second pce~sure greater than the first pres~ure, ~aid second pre~sure being ~uf~icient to create a uniform onse~ annular flow into the eentral channel having along the on~et edge a pla~e qub~tantially perpendlcular to the axi~ of the central channel, ~aid second pres~ure being provide~ while the valve means continue~ to prevent the respective material~ from ~lo~ing through the first and second oriices, ju~t before ving the valve means to un~lock said first ~nd second orifices, after cubjecting the mate~ial in the passageways to .~aid second pre$~ure, unblocking the ~irst and second orifices by moving the valve me~ns to provide a uniform onset an~ular ~low of ea~h of said material~ into the central channel, ~aid o~set flow in the channel being in a vertical plane rel~tive to the axi o the cen~ral channel, and ~3~

.

maintaining a pressure on said materials at least for from about 10 to about 80 centiseconds suficiant to maintain a ~teady 10w of said polymer materials through said first and second orifices into the central channel, and to provide and maintain uniform thickness about and along the annulus of the material flowiny rom the first orifice and the material ~lowing through the second orifice.

Other ~ethods of pre~ressurization and methods of utilizing prepressuri~ation to advantage are disclosed . elsewhere herein.

- The nozzle valve means alone, or~ preferably, in combination with the pressurization and polymer flow movement provided by the polymer displacement ~eans, which in the preferr@d embodiment are the five ra~s, one for each material which iq to for~ a layer, provides precise independent control over the flow of each of the polymer flow stream~ ~d concomitant ~ontrol over thickness and lo~ation of each o~
th~ layer~ of the multi-layer wall o~ the injected article.
Independent control over the ~low stream oi the inside ~urface layer A ~ate~ial and over the flow stream of the out~ide ~urface layer B material provides control o~ the layers relative to each oth~r, provides control over the relative thicknes~ of each layer, provides control ove~ the location of the interface between the flowing materials of tho~e layers and thus provide~ control over the location of the internal layer C or layers C, D, E si uated between the surface layers. Likewise, independent control over the ~low of the material of layers D and E can provide control over the locat$on o layer C~ I~dependent control over the .~low of the internal layer or layers provides ~ontrol over the thickness of the layer or layers. Thu~, one or more of the internal layers C, D, E can be controlled to be very thing and its location controlled, which is of substantial economic and technical bene~it where, for example, ~he adhesive layer material is relatively expensive and more so the internal layer C is a relatively expensive polymer functioning as a ~1 ~5~ '7 gas barrier. If the barrier material i~ adversely sensitive to one or both of the environments inside or outside the injected article, control over the location of the barrier layer within the ~all of the article is important in order to maximize the effectiveness of the protection of the barrier layer which is provided by the layer or layers on either qide of the ~arrier layer.

For example, when it is desired to form a container for packaging an oxygen sen~itive food product which requires thermal processing in the container at a temperature which qterlli~es the packaged food, the injection molded or blow molded container utilized, while preferably having a bottom wall whose average thickness is less than the average thickness of the container side wall, preferably also has a barrier layer which is thicker in the bottom s~all relative ko the bottom wall total thickness than it is in the side wall relative to the side wall total thickness. Although the total thicknes~ of the bottom wall may be changPd relative to the total side wall thicknes3 by changi ng the geometry of the blow mold toollng used for making the parison ~rom ~hich the container is blown~ or the temperature o tAe tooling or o~
the melt ~aterial~, with the same tooling and without such modifications, the barrier layer may be made thick in the botéom wall relatiYe to it~ thickness in the side s,lall by selectively reducing the rate~ or volumes of flow of the one or both of the ~tructu~al materials during that portion o~
the injec~ion profile which ~orms the bottom portion of the parison, and which when blow molded, forms the bottom wall of the container~ This permits thinning one or both of the structural layers A and ~ in the bottom wall and thickens the C layer in the bottom wall regardless of whether the rat~ or volume ol flow of the barrier layer C is held constant or is increased. Alternatively, during a said injection profile por~ion which, as disclosed in Fig. 142, can be from about l . O to about l .1 3econd, the flow rate of each s~ructural layer A, B and of each adhesive material D, E may be held constant while the flow rate of the barrier layer C is ~2~

rapldly increased~ Preferably, the flow rates of both materials A and B are decreased while the flow rate of barrier layer C is increased or held constant. Thsse techniques also thicken the barrier layer C in the bottom wall, relatlve to that layer's thickness in the side wall.

- To move the location of, for example, a moisture sensitive barrier layer in the bottom wall away ~rom the inside surface o~ th* ~ontainer to provide greater protection to the barrier from moisture in ~he co~tainer, the flow rate of the outer material ~ i de~rease~, th~ flow rate of the inner material A is either increased or held constant, and the ~low rate of the barrier layer C is held constant.

~ aving the ability to provide a thicker internal or barrier layer relative to the total thickness of all layers~
in the bottom wall of container~ of this invention, provides economic advantages over other containers, ~or example multi-~ayer ther~oformed plastiG contalners wherein the inter~al layer is o a uniform thickness relative to the to~al thickness throughout the bottom and side wall, each of which are stretched uniformly fro~ a blank during formation o~ the container. Therefore, providing a thirk internal layer in the bottom wall of a thermoformed container requires that the layer be thick in the blank and nece sarily means that the layer in the thermoformed container made rom the blank will be as thick relative to the total thickness, in the side wall a~ in the bottom wall.

Another advantage provided by the use of an individual source of polymer displacement and pressurization ~uch as a ram for each layer i3 that the capability of the valve means to rapidly traverse eac~ and all orifices, particularly when they are narrow and close to each other, minimizes the effect of slight errors in machine tolerances or design of, qay, a choke in one or more shells or in one or more but less than all of the eight co-injection nozzles, and minimizes the effect of any such error~ in the initiation and - 2~ -~2~5~

terminatlon of flow substantially ~lmultaneou ly and substantially ldentically ;Ln all co-injection no2zle~.

Although the previou~ly di3cussed preferred embodiment of the process of thi~ invention which provides the aforemen~ioned precise independent control employs a ram for each material which is to form a layer of the article, it is to be appreciated that al les~ preferred process of thi~
invention u3es a single ra~l for a material which will comprise more than one layer. Though le58 preferred, this common ram 5y tem with the valve means provides sufficient independent control over the layers. More particularly, if the outer layer and the inner layer are of the same material, a single materi~l movement mean~, displacement means or pressurization source can be employed for both streams. The features of this invention which per~it the use of a co~mon ~ource of preq~urization for a material which forms two l~yer~ o~ an article, are the valve means of this invention which permits the lndependent stopping and starting the ~low of these layers of common material~ even when both a~e pres-~urized, and the design of the runner system which provide an equal flow path for each melt stream of material that forms a corresponding layer of the item to be iAjected.
Somewhere between the ram and the no~zle orifices, the flow cha~nel for t~e common material is split into two flow channels to take the material for the two layers to each co-injection nozzle.
.
Moreover, in a preferred embodiment of such a common ram system, even the relative flows of the two stream~ of common material, for example, ~or the two structural layers can be controlled by moving the pin within the ~leeve to partially block and reduce the ~low of one of the melt streams, for example, of the A layer material through the sleeve port. To achieve the maximum range of control, it is preferred that, for example, the ~low re~istance of the melt channel or the inner A layer be less than that forming the outer B layer when the ~leeve aperture is fully open. The ~/

2~

melt channel in this context is measured ~rom either the pres~ure source or from the point o~ splitting or branching into the two flow streams, to the central channel. In this way it will be possible tc\ ~ary the flow of the inner A layer to be either greater or less~than that of the outer B layer by utili2ing the valve means for controlling the degree of hlockage. This will apply whather the article to be ormed i~ to have three, five or any plural number o~ layerg. In the preferred embodiment of a co-injection no~zle of ~uch a common ram sy~tem, whereim the passageway for the A layer material into the ~entral channal i~ by design larger than the ize o~ the other orifices, with a ram co~mon to a material for the A and B layers, equal flow~of the common material can be provided with the val~e means by using the pin to partially block the entrance, while the orifice Por the ~ layer i5 unblocked. A~ for controlling the radial distribution of layer3 in a combining area or injection cavity by use a~ the common ram system, it is effected more by pin manipulation than by ram displacement pro~ile. ~or e~ampl~, to decrea~e the outside structural layer thickness in order to ~hift the internal barrieÆ layer, o~ the adhesive and barrier layers, to~ard the out~ide of a parison or container, the solid pin i~ withdra~n to increa~e the size of the unblocked portion o~ the entrance of the passage~ay for the A layer material. This increases the flow of the polymer ma erial for the inside layer, ~, and decreases the amoun~ of material available for forming the outside layer, B, and thereby attains the d~sired radial layer distribu~ion. W~en using the common ram system with valve means, in knitting the internal layer with itself by moving the pin forward to block the flow o~ the common material for the A layer through the sleeve port, more of the common material ~low is diverted to the passageway for the B layer. This may be unde~irable for certain high barrier container applications because it may result in an interruption in the continuity of the internal layer material in the bottom o~ the container, and in an internal barrier layer being too close to the inside of the container by reason of the ~ncreased flow and thickness of ~Y~
O

rj~7 !

the B layer materlal. ~owever, thacie r~9iult3 may be minimi2ed or prevented by reducing the di~placement of the co~mon ram upon blocking of the entrance for the A layer.

~ imilarly, in the c:aqe oP a five, saven or comparable layer article, a common pressure source can be employed for two or more int:ermediate layer material streams when they are comprised of t:he same material.. In the case of a five layer article of this invention, the flo~ of the intermediate layer stream, ~lere, D, next to the inner layer stream, here, A~ can be modulated by partially blocking its orifice with the sleeve. A~ain, as previously e~plained in relation to the A and B layer materials, to achieve the maximum range o control, the resistance to flow in the intermediate layer 9 stream next to the inner layer stream should be le9i8 than that o the intermediate layer stream, here, E, next to the outer layer stream, ~, when both orifices are completely unblocked~

~ til~zin~ the aforementioned common ram syste~, the previously discu-~ed delamination con~ideratlon between the C
layer and the inner l~yer A i~ five layer injection molded articles can be avoided by using the common ram to prepressuri~a the common adherent material for the intesmediat~ ~ and D layer~ to the same level while their respective fourth and fifth orifices are blocked by the valve means, and withdrawing the sleeve to fully unblock ~he ori~ices for ~he ~ and C layers but only to partially block the orifice for the D layer. This will cause the desired flow of an abundance of E material into the cent al channel which i3 sufficient to flow about the leading edge of the C
layer material, join the leading edge of the D layer and fully encalpsulate the C layer leading edge with intermediate adherent materialr Thus, while the common ram system does not provicle the ~iame flexibility and precise degree of control as~ i5 available with the preferred individual ram-to-inclividual layer system, it does provide a suitable alternative.

Another and significant feature of the independent layer control pro~ided by ~aither the Yin~le ram-~or-each layer system or the common ram-for-two layer3 ~ystem i5 that they can be used according to the present in~ention to effect foldover of the terminal end of one o~ ~ore of the internal layer~. The preferred flo~ of polymer material in the noz31e central injection channel and in the injection cavity is laminar, wherein linear polymer flow velocity is maximum at a fast flow streamline, which, in the injection cavity, usually i~ at or ~ear the center liLne of polymer flow and dimini~hes on either side thereof. The location of the fast flow ~treamline will, however, be other than the center line i the two wall temperatures are different or if the viscosity of the inside polymer stream i~ different from the out~ide stream. The flow of polymeric material in the no~zle inje tion channel has a flow streamline which corresponds to the fa~t flow ~tre~mline in the inje~tion cavity~ ~y ~electively changing the ~low of one or ~ore polymer stream3 on one ~ide of an internal layer, relative ta the flow of one or more polymer stream~ on the other side of that internal layer, during a part of the injection cycle ~s de~cribed below, the locatio~ of the internal layer relative to the fa~t stre~line may be ~el~ctively ~a~ied o~ mov~d so a~ to cause ~he terminal end of the in ernal layer to fold 07erO

If it is present, time bias of initial flow of the internal layer material into the nozzle central channel around its circumference~ or velocity bia~, ~an~ as stated praviou~ly, re~ult in the terminal end of the internal layer having dif erent axial positions at various sections around the clrcum~erence of the injected article. Should this flow condition continue, the terminal end of the internal layer would not extend a~l the way into the end portion of the in3ected article at all sections around its circumference.
Such re3ult of time bias or velocity bia~ can be ~ub~tantially reduced by ~olding over the biased terminal end to provide a substan~ially unbiased overall leading edge o~
the internal layer. It may be reduced by folding over a ~Y ~

least a portion, preferahly the leading portion of the marginal end portion of the internal layer by selective independent control of the location and flow o the polymer streams, as stated above, so as initially to introduce the internal layer at a flow streamline which ls not coincident with the fast flow streamline and then moving the layer to a second location which is either relatively more proximate to or substantially coincident with the fast flow streamlina or i9 across the flow stream, i.e., past the fast flow ~treamline ~here the flow velocity 1~ maximum, to a second location on the other side of the fast flow streamline and not too far ~rom it. As a result, at the conclusion of polymer movement in the injection cavity, as illustrated in Fig. 135 the biased terminal ends, here designated 1117 and 1119, of the folded over portion of the internal layer have been foldad over along fold line 1125 80 that the internal layer e~tends into the marginal end portion of the injec~ed article. Thus, at the conclusion of polymer movement in the ~njection cavity, the internal layer extends into the end portion of the inje~ted article at substantially all sections around its circumference.

Broadly, foldover is achieved by a method, according to the present invention, of injecting a multi-layer flo~
strea~ comprising three layers into an injection cavity in which the speed of flow of the layered stream is highest on a ~ast flow streamline positioned ~ntermediate the boundaries of the layered straam. Tha method comprises the steps of establishing the flow of material of a first Layer of the flow stream and the flow of material of a second layer of the flow stream adjacent to t~e first layer to form an interface between the flowing materials of the first and second layers. In the preferred embodiment, the first,and second layers of the multi-layer flow stream form the in~ide and outside surface layess of the injected article. The interface between the flowing materials of the first and second layers i po~itioned at a first location which is not coincident with the fast flow streamline. This is .
~5 - ~3 -accomplished by selective control over the flow of the first layer material and o~ the slecond layer material. The ~low of material of a third layer o:F the ~low stream is then interposed between the first and second layers with the location o~ the third being at a position which is not coincident with the fast flow streamline. As noted above, the third layer material orms an internal layer of the injected article and may be a moisture-sensitive oxygen barri~r material. ~he location of the third lay@r of the multi-layer flow stream is then moved to a ~econd location which is sub~tantially coincident with the fast flow strea~Line. PreferaSly, the third layer is moved to the second location when or shortly after its ~low has been interposed between the first and second layers, and, most preferably, when or shortly after the flow o~ the third layer ~aterial has been interposed between the first and second layer3 at ub~tantially all plaGes across the breadth of ~he layered ~t~eam~

The pre~ent foldover invention also broadly encompas~es the movement of the location o~ the third layer of ~he multi-layer flow stream from a ~ir~t location on one side of the faRt flo~ ~traamline to a ~econd location whicb i~ intermediate to the fir-~ location and the fa~t low R$reamline or more proximate to the fa~t flow ~treamline, and wh~h is theEefore a faster flow ~treamline than i~ the first streamline.

The present foldover invention also broadly encompa~ses the movement of the location of the third layer o~ the multi-layer flow stream from a first location on one side of ~le fast flow strea~line, acro~3 the fast flow -~trea~line, to a ~econd location which is not coincident with the fast flow ~treamline. Such movement of the location of the third layer to its second location is preferably carried out when or ~hortly after the flow of the third layer material has been interposed between the first and ~econd layers, and, mo~t preferably, when or shortly after the flow of the third layer material ha3 been interpo ed between the fir~t and second layers at substantially all~places across the breadth of the layered stream.

More 3pecificially, in carrying out the present method of injecting a multi-layer flow stream to effect foldover, there i3 establis,hed in the in~ection channel of an injection nozzle the flow of material of a ~irst layer of the flow stream and the flow of ~aterial of a second layer of the flow stream adjacent to the first layer to form an interface between the flowing materials of the fir8t and se~ond layers. The multi-layer flow stream in the injection channel of the no7zle has a flo~ streamline which correspond~ to the fast flow streamline in the injection cavity. The rate of flow of the first layer matarial and the rate of flow of the ~econd layer material are ~elected to position the i~terface between them at a first location which i8 not coincident with the fast flow streamline in the injection cavity, o~ which is not coincident with the flow streamline i~ the nozzle injection channel ~hich corrasponds to thq fa~t flow streamline in the injection cavity. The flo~ of material o~
a third layer of the flow stream is interposed between the first and second layers with the position of the third layer being at a first location which is not coi~ident with the fast flow streamline in the inje~tion cavity, or which is not coincident with the flow streamline in the nozzle injection channel which corresponds to the ast flow ~treamline in the injection cavity. The relative rates of flow of the first and second layer materials a~e then adjusted to move the location of the third layer to a second location. The 3econd location is 3ubstantially coinciden~ with the fast flo~
streamline in the injection cavity, or with the 10w straamline in the nozzle injection channel which corresponds .
to the fast flow streamline in the injection cavity.
Alternatiqely, the relative rates of flow of the fir~t and second layer materials are adjusted to move the location of the third layer ~rom the-ir3t location on one side of the fa3t flow streamline, across the fa t flow ~treamline, to a ~1 _ ~ _ second location which i5 not coincident with the fast flow ~treamline. In terms of the flow streamlines in the no~zle injection channel, the relative rates of ~low of the ~irst and second layer materials are adjusted to move the position of the third layer in the nozzle injection channel from a fir3t location on one side of the fl~ow ~t~eamline in the channel that corresponds to the fast flow streamline in the injection cavity, across the flow streamline in the channel that corresponds to the fast flow streamline in the injection cavlty, to a second location in the channel which i~ not coincident with the flow streamline in the channel that corresponds to the fast flow streamline in the injection cavity.

~ ost specif,cally, in carrying out ~he present method of injecting a ~ulti-layer flow Rtrea~ to cau~e ~oldover of the leading edge of a flowing annular stream of internal layer material, there i~ provided a method of ~njecting, by means o~ a nozzle having an injection channel, a multi-laye~ ~low ~ ream comprising th~ee layers. The multi-layer ~low stream is injected into an in~ection cavity in which ~he ~peed of flow of he stream is high@~t o~ a fast ~low streamline positioned intermediate the boundaries of the layered ~trea~. The method comprises establlshing in the nozzle ~njection channel the flow of material of a first layer of the flow stream and the flow of material of a second layer of the flow strea~ adjacent to and around the first layer to form an annular interface between the flowing materials of the first and second layers. The flow stream in the nozzle injectioA channel has a flow streamline which corresponds to the fast flow streamline in the injection cavity. The rate of flow of the first layer ~aterial and the rate of f:low of the second layer material are selected to position the annular interface between the 10wing first and second layer ~aterials at a first location in the nozzle injection channel which is not co~incident with the flow streamline in the channel that corresponds to the fast 10w streamline in the injection cavity. The flow of material of g a third layer of the flow stream i5 interposed around the first layer and between t.he first and second layers with the location ~f the third layer being at a position which is not coincident with the flow streamline in the nozzle injection channel that corresponds to the fast flow streamline in the injection cavity. When o;r shortly after the flow o~ the third layer material has been interposQd between the first ~nd second layers at substantially all places around the circumference of the annulus between the first and second layer , the relative rates of flow o~ the first and ~econd layer materials are adju~ted to move the locatlon of the third layer in the nozzle injection channel to a ~econd location in the channel. That second location may either be ~ubstantially coinciden~ ~ith the flow streamline in the channel that corresponds to the fast flow streamline in the inje~tion cavity, or that -~econd location may be across the flow streamline in the channel that corresponds to the ~low ~t~e~mline in the inje~tion cavity. In the latter case, the location o~ the third layer in the injection channel 1~ moved ~cro~s th~ flow s'cre~line in the channel that correspond~ to the fast flow strea~line in the injection cavity to a s~cond location in the in~ection channel which is not coincident with ~he flow stxe~mline in the cha~nal that corresponds to the fa~t flo.w streamline in tha injection cavity.

The preferred method of injecting a multi-layer ~low stseam to cause foldover of the leading edge o~ a ~lowing annular stream of internal layer material will now be described with particular reference to ~ig3- 130-137 which schematically depict a portion of a simplified form of nozzle as~ambly 296 adapted, for illustrative purposes~ for the 10w o~ a thl:ee-layer ~low stream. ~he material o~ layer A of the flow stream, and which forms the inside layer o~ the injected article" flows axially through the nozzle central channel 546 which will herein be referred to as the nozzle in~ection channel or the injection channel. The material of layer ~ of the 10w stream, and which forms the outside layer o~ the injectecl article, flows between nozzle cap 438 and outer ~q ~ ~ -- .

3hell 436 and then through annular orifice 462 into the injection channel. The material of layer C o~ the ~low stream flows, in this illustrative embodime~t, between outer shell 436 and inner shell 430 and then through annular orifice 502 into the ~n~ec~ion channel 546. In the injection channel, the material flow stream ha~ a flow streamline 1101 (generally designated by a dash line) which corresponds to a fast flow streamline 1103 (generally designated by a dash line) of the mater~al flow stream in the injection cavity 1105, which is bounded, on one side, by t~e surface 1107 o~
core pin 1109 and~ on the other side~ by the surface 1111 of injection mold 1113. The speed of flow o~ the material flow stream in the i~jection cavity is highest on fast flow streamline 1103.

Re~erring to ~ig. 130, the ~irst step of the method is e~tablishing in injection channel 546 the ~low of material of a f~rst layer of the flow stream, layer A, and the ~low of material of a second layer of the ~lo~ stream, layer B, adjacent ~o and around the fir~t layer to form an annular interface 1115 bet~een the ~low~ng mate~ials o~ the first and second m~terial~, for layers A and B respectively~ In the next ~tep, the rate of flow o~ the layer A material and the rate of flow of the layer ~ matPrial are selected to position th~ interface 1115 at a first location in the injection channel 546 ~hich is not coincident with ~he flow streamline 1101 in ~he channel that correspond~ to the ~ast flow streamline 1103 in the injection ca~ity 1105. The first location of interface 1115 is close to, but i5 o~fset from, flow strea~line 1101. The relative rates of flow of the mater~al o~ layer h with respect to the material of layer R
are initially selected or later adjusted so that, just prior to introducing the layer C materlal into the nozzle central channel, the interface 1115 between the ~lowing A layer material and the flowing B layer material is positioned at the locat:ion where it is desired to locate the layer C
material when it is first introduced into said channel. The fir3t ancl second steps may take place substantially _ ~ _ ~, ~?d ~i Çi ~2 ~ ~7 oonour~ently. In the illustrated embodim@nti the interface 1115 is radially outboard of flow streamline 1101, i.e., radially farther away from the central axiY of the flowing material streamsO As will he described, this will result in the folded over portion of the third layer matsrial being positioned between fast flow streamline 1103 and the outer surface of the out~ide layer B~ When it is desired to position the folded over portion of the third layer,between the fast f low ~treamline l]L03 and the in~ide sur~ace o~ the in~ide layer A, the interface lllS will be positioned at a first location which is radially inboard of flow streamline 1101, i.eO, radially closer to the central axls of the flowing material streams.

Referring to Fig. 131, the third step is interposing the 10w of material of a third layer o~ the flow stream, layer C, around the first (A) layer and between the first (A) and ~econd SB) layers~ In the preferred e~bodiment~ the thlrd layer ~also re~erred to h~rein as an inte~n~l layer) is the bar~ier layer which, for exa~ple, may be EV0~. The location of the third layer i at a position which ls not coincident with the flow streamline 1101 in the chann~l 546 tha~ correspond to the fast flow ~treamline 1103 in the Lnjection oavity 1105. At the stage of the proce~s depicted in Fig. 131, the ~low of the third ~C) layer material ha been interposed between the ~irst and Recond layer~ to the extent that the third layer material is interposed at substantially all places around the circumference of the annulu~ between the first and second layers. For the purpose of allu~trating the benefit of the foldover a-~pect of the pres~nt invention, ~igO 131 4hows time bias of Lnitial flow of the internal layer (C) material, into the injecticn channel 546, around tbe circumerence of the channel. Thus the terminal end o~ ~he internal layer has an axial leading portion 1117 and an axial trailing portion 1119 at different places around the cir~umference of the annular terminal end~

When, or shortly after, the flow of the third (C) . ~5l layer material has been interposed between the fir3t and ~econd layers at substantia.lly all places around the circumference of the annulus between the first and second layers, the relative rates of flow of the first (~) and ~econd (B) layer materials into the injection channel S46 are adjucted to move the location of the third layer to a second location in the channel 546 ~see Fig. 132). The second location of the third layer i relatively ~ore proximate to 7 or ~ubstantially coincident with the 10w streamline 1101 in the injection channel which corre3ponds to the fast flow ~treamline 1103 in the injection cavity (see Figs. 136, 137), or the ~econd location is across the flow ~treamline 1101 (see Figs~ 130-135). Because it is sometime~ difficult in practice to place-the second location of th~ third layer precisely on flow streamlina 1101, it is preferred to move the location of the third layer ac~oss streamline 1101 in ord~r to ensure that at least some part 1121 of the material of the third layer is coincident with streamline 1101 at substantially the same axial loca~ion in the multi-layer flow stream at ~u~stantially all locations 360 around the annulus of the third-laye~ material flow strea~ A~ will be explained, it i~ this part 1121 of the thlrd layer material which, by reason of its being located on the f}ow streamlina 1101 ~wbich co~respond~ to the ~a~t flow streamline 1103 in the injection cavity), will have the highest speed of flow in ths injection ~avi~y 1105. Part 1121 will form a fold or ~fold li~e~ about which the third layer is folded over. The old line will beco~e the ~leadlng edge~ of the third layer.
Becau~e part 1121 of the third layer cros~ed over the flow streamline 1101 (and thu~ at that cross-over place became coinciden1: with the streamline 1101) at -~ubstantially the sam~ flow stream axial location around substantially all 360 of the cir.cumference of the annulus of third layer material, there will be substan~ially no axial bias of the fold line and hence substantially no axial bias of the leading edge o~
the internal (C) layer. As a re~ult, the folded over, leading ecige of the internal layer will extend into the marginal end portion 12 of the wall 11 of the injected - ~iO -article at substantially a:Ll locations around the circumference of the end portion at the conclusion of polymer material movement in the injection caYity. Thus, the detrimental effect of any l:ime bia of initial flow of the internal layer (C) material will have been overcome.

` In the case where there is time bias of initial flow of the third or internal (C) layer, the time when the ~low of that material has been interposed between the first and 3econd lay~rs at ~ub~tantially all place~ around the circumerence of the annular interface between the first and second layers is determined as follow~O An injected article or a free injected hot of the multi-layer ~low stream i5 examined and the axial separation between leading portion 1117 and trailing portion 1119 i3 measured. From the measured axial eparation and the known geometry of the nozzle central channel 546 and o the re~t o the nozzl~
a3~em~1y, th* time interval between entry of leading portion 1117 into the channel 546 and entry of trailin~ portion 1119 i~to the channel may be calculated. In the preferr~d e~bodi~ent, the ti~ when leading portion 1117 begin~ to ~lo~
$nto the nozzle ¢antral channel is the time ~hen the ~leeve sao be~ins to unblock orifice 502. The sum of this time plu~
the above-calculated time interval is a close approximation of the time when the in~ernal layer ha~ been fully, circumferentially interposed between the ~irst and ~econd layers.

If, ju~t prior to the introduction of the layer C
~aterial into the nozzle central channel, the location of the interface between the ~lowing A layer material and the ~lowing B layer material i5 radially farther from the central axi~ of t.he flowing melt ~treams than the location of flow streamline 1101, the previously-de~cribed change in A~B flow ratas i9 selected to move the interface location toward the central axis to a second location closer to the central axis of the flowing melt stream~. The second location i5 either coincident with the flow streamline 1101 or the ~econd . ~53 - ~1 ~2~5~

location i3 across the ~treamline 1101 and d oser to the central axis of the flowing melt stream~. Thi~ will causa foldover of the terminal e~d of the internal layer C material to occur and the folded portion of the layer C material will be located between the remaining, unfolded portion of the layer C material and the outside ~urface o~ the injected article at the conclusion of all melt material ~tream move~ent in the i~jection cavity at the end of the injection cycle. Conversely, if, just prior to th* introduction o~ the layer C material into the nozzle central channel, the location of the interface between the flowing A layer material and the 10wing B layer material is radially closer to the central axis o~ the flowing melt streams than the location of flow streamline 1101, the relative flow rates of the layer A materi?l and the layer B material will be sub~equently changed to move the interface location acros~
tbe flow streamline 1101 to a second location which is either coincident wit~ flow streamline 1101 or is across ~low st~2amlin~ 1101 and which i9 f r her fro~ the central axis of the flowing melt stream~. This will Gause foldover of the te~minal end of the internal layer C material to occur, an~
the ~olded portion of the layer C material will be located betw~en t~e re~aining, unfolded portion of the layex C
material and the in~ide surface of the inject d article at the conclu3ion of all melt stream move~ent in the injection cavity at the end o~ the injection cycle.

Referring to ~ig. 132, the relative rates of ~low of the fir~t lA) and ~econd IB) layer materials, are adjusted (B
increased, A decreased) to move the location o the internal layer to a second location 1123 which is across, i.e., on the other sicle of, the flow streamline 1101 in the injection channel t:hat corrQspond3 to the fast flow streamline 1103 in the injec:tion cavity.

~ he injection of the multi-layer 10w stream is continuedl, and the part 1121 of the third layer material ~hich wasl located on flo~ streamline 1101 in the injection ~2~

i6~

location is acros~ the ~raamlirie 1101 and closer to the central axls o~ th~ flowing melt streams~ Thi~ will cause i~oldover of the termlnal end o She internal layer C ~aterial to accur and the folded portion of the layer C material will be located between the remaining, unfolded portion of the layer C material and the out~ide surace of the injected article at the conclusion o~ all melt mat~rial stream movement in the injection cavity at the end o~ the injection cycl~0 Co~Yersely~ i~, ju~t prior to the introducti.on of the layer C: material into the nozzle cent~al channel, 'che location o~ the int rface between the ~lowi ng A layer mater~al and the flowing 8 layer mat~rial i~ radially closer to th~ c~rltral axis of the flowing ~elt stream than th~
locatiorl o~ ~1GW strea~line 1101, the relati~e flow rat~s of the layer A material and the layer B material will be subsequently chang~d to Dloqe the inter~ace locatiorl acro~s the 10~ ~treantline 1101 to a ~econd location whic:h is either coincident with flow ~treaD~ e llQl or i~ a~ro~s ~low 81:rea~1ine 1101 and which i~ farth~r from the central axi~ of the ~lowlng m~lt 5tream3~ hig ~ cau~e ~oldover of 1:he termi~al e~d of the inte~al laye~ C mat~rial to occ:ur, a~
the olded portion of: tl~e layer C ~at~rial will be located b~tween the remainln~, unfolded portion o~ the layer, C
material and the insid~ 3ur~EaGe o the injected arti.cle ~t the concIu~lon o~ all melt ~tream moveEnent in the injection caYity at tho end of the injeCtiOA cycle.

Re~erring to Fig. 13Z, the ~elative rate~ of f}ow of the.irst (Al and second (B) layer materials are adjusted (~
increa~d, A d~c~eased) to move the location of the internal layer to a second lo~ation 1123 which i~ across, i.e.~ on the other slde o~, the flow streamline 1101 in the injection channel that correspond3 to the fast flow streamline 1103 in the injectio~ cavity.

The injection of the multi layer flow stream is continued, and the part 1121 of the third layer material w~ich ~a~ located on flow streamline 1101 in the injection ~5~

channel is located on ~a~t flow streamline 1103 in the injection cavity. Part 112.1 has a speed o~ flow in the injection cavity whic~ is faster than that o~ either ~he axial leading portion 1117 or axial trailing portion 1119 of the terminal end of the internal (C) layer material. As the injection continues~ part 1.121 forms a fold or ~fold line~
1125 Isee Fig. 133) which f:Lows faster than portions 1117 and 1119 and overtakes them~ ans~ thus becomes the leading edge o the internal layer. In Fiq. 133 r folded part 11~1 has overtaken axial trailing portion.lll9; in Fig. 134, the injection has further continued and folded part 1121 has now overtaken axial leading portion 1117. The leading edge o~
~he i~ternal layer is the fold line 1125 of the folded over internal layer at olded part 11~1. The leading edge of the i~ternal layer has ~ubstantially no axial bias and, as shown in ~ig. 135, extends into the flan~e portion 13 of the injection molded article, here a parison, at substantially all location3 around the.~ircu~ferenc2 thereof at the conclu.$on of polymer material movement i~ the injection cavity.

A~ mantloned previously, when or shortly after the flow of the third layer material has been interposed be~ween the fir~t and second layerY at sub~tantially all places around the circum~er~nce o~ the annular inter~ace b~tween the first and second layer materials, the relative rates of 10w of the first and qecond layer materials into the injection Ghannel are adjusted to move the location of the third layer to a second location in the channel. FigsO 136, 137, illustrate the second location being substantially coincident with the f.low --treamline 1101 in the injection channel which corresponcls to the fa~t flow streamline 1103 in the injection cavity.

Referring to Pig. 13G, the relative rates of flow of the ~irst (A) and second (B) layer materials are adiusted (B
lnc~eased, A decreased) to move the location of the internal layer to a second location 1127 which is substantially ~4 - .

$~

coincldent with the ~low streamline 1101 in the injection channel that corre~ponds to the fast flow straamline 1103 in the injection cavity 1105. Portion 1129 of the third layer material is the part of~the third layer material which ~irst became substantially coincident with flow streamline 1101.
As the injection of the multi-layer ~low stream continues, portion 1129 forms a fold or fold line about wbich the third layer is folded over. (See Fig~ 137) A5 before, the fold line becomes the leading edge o~ the third layeru Becau~e part 1123 of the third layer material beca~e substantially coin~ident with the flow streamline 1101 at substantially the same flow ~tream a~ial location around substantially all 3~0 of the circumference of the annulus of third layer material, th~re i3 substantially no axial bias of the fold line and hence substantially no axial bias of the leading edge of the in~ernal ~C) layer.

The pres~nt foldover invention has particular ut~ y in apparatus and process which, in a multi~nozzle mach~ne, ~imultaneously injectio~ mold~ a plurality of multi-layer articles. For ~xample, in an eight-cavity ~ach~ne ther~ ~ay be a small ti~e bias o~ initial flow of internal layer ma~erial into the injection channel o~ one o~
the eight nozzle assemblieq, leading to the production o~
less than optimum a~t$cles from that nozzla and as~ociated injection cavity. 3y utllizing the aspect of the present i~ention which provides a substantially eq~al flow and flow path to each nozzle for each separate stream of polymer ~ate~ial, substant~ally the same relative rates of ~low of the first and .~econd layer materials can be obtained in each of the eight nozzle assem~lies. Then, by an appropriately-timed change of rate of movement of ram 232 (~or layer B material) and ram 234 (~Eor layer A material~, there is caused to occur a substantially simultaneous adjustment in each of the eight nozzle3 of the relative rates of flow olE the ~irst (A) and second (B) layer materials~
This cause mo~ement, substantially simultaneously in each of the eight nozzles; of the location o~ the third layer in ~he ~7 ~6~S~

injection channel from the first lo¢ation, previously described, to the second ].ocatio~, al~o previously described. The movement of the third layer location ~rom the first to the second locati.on is timed to occur when or shortly after the flow of the third layer material has been interpo~ed between the first and second layers a~
substantially all places around the circumference of the an~ulus or interface between the filst and second layers in all of the nozzlesO Thus, the third layer will be concurrently ~olded over ln the articles made in all o~ the injection cavities and the e~fect of time bias of initial flow of the internal layer in any one or more of the injection nozzles will be corrected.
.

It should be appreciated that in the embodiment of the injectiQn mold 1113 shown in Figs~ 130-137, surface 1111 of the injection mold ex~endin~ from and ~orming the trans$tion ~om th~ sprue orifice to the portion of the ca~ity 1105 which forms the pari~on wall, has a smooth radiu~
o curvature wh~ch provides a greater volume for material than a conventional narrower orifice with a ~harper, angular transitional surface juncture. The greater volume permits more inner structural A layer ~aterial to ~orm between the surface of the tip o~ the core pin 1109 and the internaL C
layer ~aterial. This can be ad~antageous when the C layer material ~s a ~oisture ~ensitive barrier material and it i-~desired to for~ a thick layer o~ inner structural material to protect the internal barrier layer of the finished container ~rom liquid contents.

It should also be appreciated by those skilled i~
the art reading the preRent specification that the foldover invention is applicable to a multi-layer flow stream having ~ore than three layers such as, for example~ the five-layer flow ~tream previously described and which consists of layers A, 3, C, D and E. With reference to that five-layer flow stream, the terms ~internal layer~ or "material of a third layer~ or ~third layer~ ars to b~ understood as meaning ~he ~6;~

three adjacent internal layers ~C, D and ~) which are caused to flow and to move substantially as a unit from the first location to the ~econd location in the injection channel.

The task sequence, or process flow, for a single cycle is shown in Fig. 140. The time axis of Fig. 140 corresponds to the time axis shown in ~ig~. 142 and 143. ~or purposes of explanation, a cycle will be defined as a point tA in time beginning ju~t prior to the clamping operation, effected by mean~ of the hydr~ulic cylindar 120 (Fig. 11), moving the moveable platen toward and away fro~ the fixed platen, along the tie bars, and ending at a corresponding point in the next cycle. Thus, the beginning of an initial cycle takes place just prior to a clamping operation at time tA. As the cycle progresses, the cylinder 120 b~gins to move and at time tB the clamping pres-~ure starts to build up. An accurate clamping action occurs IDY virtue of the process contrcller opening and d osing valves to regulate the oil flow to the hydraulic cylinder. Purthar, a~ time tB, the timing cycle ~or blow moldlng begins. Thi~ consist~ o~ a blow air delay follo~ed by a blow air duration of ~pecific time length. The blow air delay allows su~ficient time for clamping pressure to reach the desired limit prior to the blow molding operation so a~ to prevant.misshapen articles.
At time tC, when the clamp is at full pressure two other timing cycles begin, the first being the injection/recharge cycle, described in Figs. 142 and 143, the second is th*
ejection cycle. At the end of the blow ~old delay, the ejection of the molded article from the blow ~old occurs by opening tha !Dlow mold and pushing out the ba~e punch. During this same time period starting at tC, in the injection molding operation, after an initial injection delay, the injection profile, which will be described in conjunctlon with Figs. 142 and 143, takes place. At time tD, the injection operation is~completed and a period of time for parison conditioning occurs. Parison conditioning allows the parison to cool to a temperature sufficient for blowing the parison in the blow mold.
~57 - ~7 -6~

At the end o~ the parison conditioning, at time tF, a signal is provided for cut off of the air blowing cycle in the blow molder i~ it has not already been turned off by the blow air duration timer. At the same time, the opening of the elamp iQ initiated. Af.ter an initial delay period during which the clamping pressure! drops, a further time period allows ~or the opening of t:he clamp. When the clamp is opened the core and parisoc~ com~ out of the ~avity and withdraw to a position determined by appropriate limit switches. At this moment the shuttle starts to move so that the parison 15 then transferred to the blowing station and a further set of cores are provided in ~ront o~ the injection molding station. At this poin~, the cycle has been completed and the ~lamp closing ~ollowing shuttle movement initiates the next succe~sive cycle. Goi~g back to the time tD, at the ~ame ti~e that parison condition begins, the ending of the injection profile also starts a recovery check delay time inter~al. During the recovery check delay, the po~ition of the ~crews 3~e monitored to ascertain that the Acrews have reco~ered to their correct po3itions prior to initiating a new screw injection cycle~ Tniq is done by ~onitoring the liDit swi~ches w~ich are establi3hed on t~e screws at approprlate positions. If the qcrews have recovered properly, two actions are initiated. First, Qcrew iniection is initiated, and then ra~ ~echarge is initiated. During scre~ i~jection, the melt in the sc~ew is pressurized and, if the melt pre~sure in the BCrew exceed^q the melt pre~sure in the raQ/runner system, a check valve opens allowing melt ~o be trans~erred from the screw to the ram/runner system. Ram recharge is preceedad by a check on which rams need rechar~ing by virtue of their po~ition at thi~ time (t~). If the rams are not at the initial po~ition of the injection profile, they need rechar~ing. The rams needing recharging are then retracted to their initial position. Since this ram movement expands the volume of the ram/runner system, the melt pressure drop , opening the check valve allowing the screws (undergoing screw tnjection) to transfer melt to the ram~, thereby recharging the rams. With the rams now at their initial profile posit:ion, a time period i5 provided to allow the pressure in the ~unner and ram block to reach equilibrium. At the end of this delay (tG), the hydraulic pres~ure to the qcrew i9 re!leased causing the melt pre~sure in th~ ~crew to drop and thereby closing the check valve trapping the melt in the ram/runner s~stem. Subsequently, screw recovery begins. At this pointt time t~, the entire operation has ~ycled to the a~ulvalent po~itions ~ith regard to all ~equences as occurre~ at time t~. The cycle then repeats.

The various runctions described hereinabove are achieved by means of a suitable ~ystem control means, described now in further detail.

In a preferred e~bodiment, referring to Fig. 141, a general system block di~gra~ for ef~ecting th~ foreqoing operaticn 1~ illu~trated~ With referen~e to Fig. 1~1, the system p~ocesso~ 2010 is coupled to control and monitor the various machine functions of the operation. Thus, the ~ystem proce~or 2010 controls th~ cycling of the clamping mechanis~
2012, tAe shuttle controls 2014, and the blow molding control 2016, and responds to inputs received from various oondition monitors and limit switches 2018 which monitor the extent o~
the movement and operation o~ the clamp m2chanism~, the shuttle control and th~ blow molding control. It will be under~tood that th~ block re~erred to as clamping control 2012 provides timed sequences resulting in the movements of the platen~3 into and out of relative positioning, an operation involving activating the hydraulic cylinder 1~0 after a specific time period, measuring its progress by limit s~itche~ appropriately positioned, and deactiva~ing the cylinder 'at th~ appropriate moment and position. Alar~
limits cam ~e 3~t if the appropriate position is not reached within a ~specific ti~e pe~iod. These operations are similarly effected in the shuttle control 2014 and blow molding control 2016 for controlling the sequences as ~et forth in the task operational Requence of Fig. 142.

_ ~ _ In conv~ntlonal i~ ction molding operatlon~, in~ection profile~ ar~ frequently set or controll2d by mean~
of a pin progralluaer or like device for pro~iding a patterne~
in; ection cycle ,, The present inveAtion makes use of di~tributed processing for more accurately monitoring ~nd cont~olling the ~ore co~plex functions involved in the novel an~ unique injection processing necessa~y to c~eate the ~ulti-l~yer article of the present inventiorl,. Thus, a control microproce ~or 2020 i provided with appropriate interfaces for recei~ing and di$playing inior~ation from a terrninal and keyboard unit 20~2. The microp~oce~sor 2020 irlterfaces further with the in~ection ~crew control 2024 which, in turn, i~ u~ed 'co upply ~tart and top ~i~nals ~or d~iving ~he thre~ injectio~ cr~w ~otors 2026, corresponding to mol~or~ 21~, 216 and 21~, ~how~ i n Fig . 11. Positiorl~ o~
the ~crew~ them~elve~, s~e l!'lg. 11, ar~ pcsltioII ~or~itored by li~it cont~ols 2028 coupl~d to the screws at appropr iate loaatior~ ot ~hown~ arld whic:h pro-7ide input signals to a po~itio~ ~ensing control 2030. Th~ sensing control 2030 convert~ the ~ignal~ to appropriate lagie level~, and feed3 th~ back to the mic~oproce~or 20~0 or appropriate erroE or abort co~trol~. The microproces~or 2020 al80 i~terface~ with the ram control ~032 which, :~n turn, l?rovide~ d~ive on s:oromand patential~ to the tlale ra~n se~vo~ ~h~w repr~ntationally :a~ 2034, and ~ore preci~ely as servo~
234 (A), 232 ~B), 252 (C), 260 (D) and 262 tE), e.g., irl ~ig. 14.
The ~ensors 2036, 3howrl in Fig. 18~, monitor the ~a~l positions and provide input ~ignals to ~ensing mean~ 2030, indicating i~proper po3itioning, thereby initiating error or abort condition~. Th~ mic~oproce~sor 2020 also interfaces with the pin ~ervo and sleeqe ~ervo controls 2040 which in turn provide dri~re or command potential~ to the two sensors 2042, e~h of which respectively control3 the relative positions of the cam bars 850 and 856 ~ shown in Fig. 30, for t~e purpos6!s of controlling the pin 834 and the leeve B00.
Po ition o~ the cam bars are monitored by ~ensor mechanism3 2044 arld pro~ide input signals to indicate improper po~itioning, thereby initiating trial or abort comditions..

~2~ 5~

All of the data received t:hrough the sensor 2030 is applied to the microprocescor 202CI or integration in the overall control sequenc~. In addi.ti4n, the microprocessor 2020 i5 provided with read only me!mory 2041 containing the programs controlling the sequences, an arithmatic unit 2043 for calculations, and a random access memory 2045 ~or performing active storage and data manipulation.

Referring to Figs. 142 and 143, a typical injection profile labelled, A~ B, C, D and E ~corresponding to rams 234(A), 232(~), 252(C), 260(D) and 262(E) respectively as seen in ~ig. 14 represent the co~mand signals in milli~olts, applied to the servo bo~rd for driving the rams which apply pressure to the polymer melt in channels A-E. The curves F
and G repr@sent the sleeve and pin displacements respectively. On the characte~istic curves A-E, positions indicated ~ith a dot along those curves and with circles on the pin and sleeve curves, represent the position~ at which th~ relative sleeve and pin displacements result in an opening of the respective feed channel and the resultant relsase o~ polymer melt into the nozzle central channel.
~ndications o~ closings on these curves are omitted for clari y since mo8t would b~ loca$ed in the area o the superimposition of ~he curvas~ The sla~h lines aLong pin and ~leeve curves represent the points at which those channels are closed as a result of subse~uent movements of the sleeve and pin. The ~pe~ific opening and closing time~ of FigO 142 are correlated to table II. The results of these movementq can be see in Fig. 143, which represents measured pressure of the melt at a fixed reference position, as set forth in ~he above de~cription, as a function of time. The variations in pressure are a direct result of the variation in ram servo command voltages, pin servo command voltages and sleeve ~ervo command voltage.

The microproressor 2020 is shown in greates detail in Fig. 144. As 3hown ther~in the concept of distribu~ed processing is employed for the various functions described.

a~-~

~, ~d ~ 5 7 The microprocessor 2020 is desi~ned as a series of circuit boards contained within a card cage having appropraite edge connectors for inter-board connections. A master processor circuit board 2046 interfaces with a Tektronix type ~006 graphics terminal, described as unit 2022 in Fiy. 141, and a printer. The microprocessor board 2046 is an Intel type 80/20-4 and consists of 8000 bytes of local programmable read only memory (PROM) addressable in hex format from 0000 to IFFF, and containing the programs needed for operation. The Intel MULTIBUS
(TM) system is employed for common databus and addressing, as well as to interface to the master processor board. The slave processor circuit board 2048, which employs the same commercially available Intel microprocessor, is coupled to the MULTIBUS and thus to the system processor 2010. Coupled to the MULTIBUS are a high speed math circuit board 2050 for the master unit 2046, and a high speed math circuit board 2052 for the slave unit 2048.
Both math boards are conventional Intel SPC 310 units. Also coupled to the MULTIBUS iS an additional 32.000 bytes of PROM/ROM
memory on a commercially available circuit board 2054 available from National Semiconductor Co. Model BLC8432, and including hex data addresses 2000 to 8FFF. An additional memory board contains 32.000 bytes of random access memory 2056, and is addressed from 8000 to FFFF. ~he overlap in memory on this board is pre-empted by the P~OM board. The board 2056 is coupled to the ~ULTIBUS for operation with the slave processor board 2048. An I~O board 2057 is provided, Intel type SBC519 , of conventional design, and provides drive signals from the microprocessor to the various solenoids used for valve activation to drive the hydraulic motors and cylinders. Opto isolation for buffering these signals from the various solenoids is provided. opto isolation, for the purpose of electrically buffering signals is provided to isolate the microprocessor board from high voltage transient or other miscellaneous noise signals which may otherwise be present in the various system sensors or limit switch positions. Further opto isolation is provided for the specific circuit boards 2058 and .
, :' . ' : ' .

~2~

2060 for processing input *Trademark ` 10 ~: .

- ~
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.
; 25 :

:

3 5 . -- 264a -, : .. . . ... , , :
, ': ' : ' - ' ' ' ~' . ' '' ." ' .

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signal~ will be described in further detall below. An additional board slot 206;' i5 provided for any additional circuit boards necessary.

~ igital ~ignals applied along the data lines through the M~LTIB~S in a~cordance! with command~ received ~rom the slave processor circuit board 2048 are provided through the digital to analog conversion circuit board 2064, which is a conventlonal Burr ~rown type ~P8304. The signals from this circuit are u3ed to drive rams A, B, Ct and D by application to a multi-channel qervo loop circuit board 206Ç which in turn prov$des conditioned analog ~ervo ~$gnal~ ~or the purpo~e of driving the servo-mechanism~ used to position the rams and pin 834 and sleeve 800. An additional digital to analog circuit board, similar to the circuit board 2064, is used to provide co~ditioned analog ~ervo signals from digital commands to the servo loop circuit board 2066 for the purpose o~ dr~ving the ~ifth ram ~ and the two pins P and G. Analog feedback signals received from the servo mechanisms are converted back into digital slgnals for use by the ~icroproces30r through an analog to digital ei~cuit board 2~70, model No. RTI1202 9 manu~actured by Analog Devices.

With referen~e to Fig. 1~5~ a circuit representa~i~e of circuit boards 2058 and 2060 is 3hown. Limit switch signal~ are fed ln along a~propriate input terminals indicated gen~rally as 2072, and fed through logic circult 2076. Circuit elements 2077 are opto i301ation circuit~
which act to shield the processor logic from machine noise, transients and the like which are present in limit switch ~lo~ing and other kinds of machine related interference.
Theae qignals are then fed to encoding units Z078, which are multiple;xing circuit~, which in turn provide appropriate output signals to unit 2080, whi~h is a conventional keyboard controll~er4 The keyboard controller encodes the input position ~or the purpose of providing a specific digital code along it,s output line through bu~fer circuitry 2082 directly on to th,e data lines described as D0-D7~ In operation, when ~ ~ 5 ~ 2~.3~

this circuit i3 addressed along the MULTIBUS, any appropriate data signal indicating a limit switch will be provided along the MULTIB~S. The part numberq employed in this diagram are co~mercially availAble conventional logic circuitry, and th~
operation of the circuit will thus be apparent to those skilled in the art.

Referring to Fig. 146, a more specific circuit detail of the servo loop board 2066, 5ho~n in Fiy. 144, and ~howing a ~ingle channel servo loop, ~ illustrated. A~ will be evident, the D-A conversion boa~ds ~064 and 2068 show~ in Fig. 144 provide the analog signals to the ~ervo loop board where they pa~3 through the servo amplifie.r units shown generally as 2090. The output of each of th~se servo amplifiers provide~ signals through a terminal connector to drive the servo valves. Posi ion ~e~dback signal~ are provided ~rom the eelocity transduce~s ~YT (such as 184, ~ig~
18B~ and the po~i~ion (linear motio~) tran ducers LVDT tsuch as la5 t ~ig . 18B) and appli~d to the input~ of th~ servo ampli~ier~ 2090~

The position transducer~, ~hown mechanically in ~igO
18A, are potentiometers with their respe~tive arm~
meehanically coupled to move linearly in accordance with their respective ~ervo3 positions. O~ cou~s~, other orm~ o~
tran~ducers may be employed. The transducess thus provide both positio~ ~ignals and velocity signal The velocity 3ignal is employed a~ a gain adjustment factor to the operational amplifier A791, while the position feedback ~ignal control~ the actual servo po~ition in the instrume,ntation amplifier ~D521. The output o~ amplifier A791 drive~ the servo valveO The velocity feedback may not be needed i the amplifier.range and sen~itivity are sufficie,nt. Although only a ~ingle loop is ~hown, it will be understood that a servo loop exists for each servo valve.

~ ig. 147 is a flow diagram showing the operation o~
the proces or 2020 of Fig. 144. The beginning point 0 in ~o6 ~2~

Pig. 147 represents the time ~equence at which the proces~or program begins its cycle, and the point 81 represent the end reference point o~ the processor cycle. Points 81 and 0 sub3tantially coincide since the new cycls beginq right after point 81. According to the conveAtion adopted in Pig. 147, the diamonds repre~ent information to be supplied or questions asked regarding various logic conditions and the information and an~wer determine the path to be taken to the next step. Thu~, the word ~yes~ os ~no~ i~ written adjacent to the arrow extending from each diamond to lndi~ate the logic condition or how the quest,ion contained within the diamond has been answered and the re~ulting path to be followed. The rectangles in Fig. 147 contain instructions to the various logic o~ memory element involved and the instruction is presumed to be carried out at tAat position in the flo~ diagram. The arrow~ on the connecting lines indicate the direction o~ flow of the ~teps through the diagra~.

With re~erence now to Flg. 147, the flow chart illustrating the programmed se~uence of the injectio~l and recharge cycle ~ontroller unit 2020 of FigO 144 will be describ~d. The microproceYsor unit 2020 is capable of two operation~, the first being the actual control of the i~jestion and recharge cycle~, and the second being a proces~
diagnosti6 check for analyzing the quality o~ the melt sy3tem referred to a~ a recharge injection sequence~ ~he diagno~tic cbeck is employed to $nsure the microproce~sorl~ sequences are working properly and provide a test routine whereby the 0ntire processor unit may cycle through but in which ~he clamp doe~ not operate. An actual operating cycle ~us~
include 1~e recharge injection ~equence with clamp operation. The recharge injection -~equence therefore per~its ~iagnostics to be provided in the proce~sor control prior to actual molding cycle~ to insure proper operation of the e~uipment:. With reference to Fig. 147, starting at reference poi~t 0, a decision i9 made at block 2110 to see whether the keyboard operator ha~ indicated a recharge injection sequence .

- 2~ -f~L2~

or complete mode. If a complete mode is indicated, then at block 2112 a second check is made to determine whether the clamp is to be closed at tbis point in tlme, and if so, at block 2114 a safety gate check is made to ascertain whether the -~witch has been closed indicating that the safety ga~es surrounding the injection molding machine are secure and in position. Ater a 50 mill~.second delay, the status line indicating an ainjection re!adyH signal is placed into ~ logic po~ition indicating that the injection ready signal is on.
When the injection ready signal is on, the clamp is then allowed to closa subject to the appropriate clamp closing conditions, the~e being that the ~old open timer ~a-~ ~imed out and that the shuttle li~it switch is tripped, indicating that the mold operation previously accomplished has been completed and the shuttle is now in its correct position.
Baginning ~t r*ference point 6, in block 211B, ~he various ram positions are read, command values are set, and ram ~election is ~ade. Thes~ value~, as will be explai~ed in further detail below, are calculated ~rom the prof ile which t~ previ~u31y set into the processor by means of the input ter~inal 2022, Fig. 141. Calculation o~ the command values based upon the profile dPtermines the proc~ss parameters by wh~ch the ultimate article is made, in accordance with these p~ofiled para~ters.

At block 2120, the processo~ actuates the solenoid valve which d~verts hydraulic oil ~o either the screw motor or to a ~ylinder driving the screw. At this time point9 the solenoid ~hifts into a condition whi~h tuEns off the screw motor but does no~ apply pressure to the screw. ~hen, at blo~k 2122, i~ the SGrew recovery check indicates that the ~crews have not recovered, as indicated by a lack of signal from a 9crew recovery limit switch, then at block 2124 the sc~ws are again ~urned on. At block 2126, a delay is provided to allow the screws further time to recover, and at block 2128 the screw positions are checked again. If screw recovery time is longer than the additional 3 seccnd-~provided, in block 2126, the program is automatically abor~ed - ~6 -62..:37 with an appropriate me sage transmitted to the operator terminal. It will be recal:Led that the plastic pellets are fed from the hopper to the scr2w. As the screw rotates, pellets are tran~ferred along the screw by virtue o~ the rotating screw helix. As the pellet~ txavel along the barrel, they are heated by e~xternal means such as electricity, hot oil or the like, and a3 they so~ten are compressed by the dimini3hing volume within the scre~
flight3. Further heating orcurs by compres ion and shearing so that the plastic melt~. This melt is then forced in Sront of the screw and, if the melt is unable to exit the barrel by virtue of closed valves, creates a pre sure against the front of the screw, forcing it backO Eventually the limit switch trips, activating a valve, and turning off the screw drive.
The melt pressure will decay as the scre~ is ~orGed back further. As the pressure is applied to the b~ck of the screw the melt pressure in front o the ~crew rise3 proportionally and will be forced out the barrel, unless the valve blo~ks the flow. Thus, at block 2120 the screw motor i~ turned o~
and screw pre~sure is set to neutral po~ltion where the sc~e~
i8 ready to fill or recharge the rams~

At block 2130, the screw motors are again turned off and at block 2132 pres~ure is applied to the back of the scsew in preparation for ejecting the melt from tha extruder. At block 2136, a recharge check i5 made to de~ermine which ram~ are to be r.echarged, an operation taking le~s than 10 milliseconds, and 1 any ram is grossly overcharge!d the system ~ill abort. An abort will pro~ide a message ~o the operator through the terminal. If any ram is to go through a recharge operation; thi-~ operation i~
initiated at block 2138~ The rams are recharged at a prescribedl rate, and i~ the ram5 are unable to move at that rate twithin prescribed error limits) the system will abort.
At thi3 point the program continues along the same ~low line to delay 2158 which provides time or the melt in the ~ams, the runner and the screw~ to come to an equilibrium pressure.

~, (D ~J¦
- ~7 -~l 2~ `5'7 Continuing to block 2160, the screw pressure is now switched to neutral, thereby stopping the screw injection mode. No longer is pressure now being applied to the back of the extruder and thus, the melt pressure in the extruder will begin to drop. As a result~ the pressure activated check valve closes, capturing the pressurized melt in the rams. A
50 millisecond delay is pro~rided before turning the screw motor back on at block 2162 starting screw recovery.

- ` At block 2166, ram positions are checked. At block2170, the processor again checks to see if the syst@m mode is to run complete or to run a recharge injection sequence. A
~no~ decision indicates the recharga injection sequence has been selected, causing the system flow along flow line 2172 to a point subsequent to the injection ready signal. ~f the complete mode is indicated, then at 2174 the injection ready logic signal is put on and as a result, the clamp close operation if not previously ac ivated, is now activated, through the system processor operator, and the injection complete signal is turned off. At this point, the microprocessor 2020 waits for the system processor, element - 2010 in Fig. 143~ to indicate that the clamp, shuttle and -blow mold controls have all been appropriately positioned.
When positioned, ~ithout error, and after an injection delay, the system processor 2010 sendY a machine start signal which hands off control of the machine operation from the system processor 2010 to the injection/recharge microprocessor 2020. In block 2176, at time reference point 53, the microprocessor receives its indication from the ~ystem processor 2010. At block 2178/ the injection ready signal is turned off, indicating that the system is ready to continue.
A complete mode check signal is again made in block 2180 in order to allow bypassing of the safety gates if a complete mode is not indicated. If a complete mode is indicated, then the safety gate check is made to insure all appropriate safety conditions are being met prior to actuating an injection sequence. At block 2184, the injection profile now begins. Injection profile consists of a sequence of steps ~,~0 pre-program~ed into the microprocessor 2020 ~or driving the ~ive rams P., ~, C:, D,, and E and the tb~O pins, ~ and G, through the desired profile which produce the actual article in accordance with the pre-qet com~and values, as previou~ly set foreh. At the completion of his operation, in block 2186 the lnjeGtion complete signal is turned on. This hands control of the ~achine functions back to the sy~tem processor 2010 at which l?oint the mold ciose l:imer i3 started, which, when timed out, allows the clamp to Op211. In the meantime, at block 2188, the mic~oproGessor checks to ~ee i~ a new profile has been entsred. I~ 80, in block ~190, t~e sy~tem calculates all o~ the new command value~ and place all value~ emory ~o be ~et durin-3 the referenee point B, in block 2118, ln the next cycle time. The ~ystem is then returned to its initial ~osition, block 2192, and tbe operatio~ the~ repeats . It will be evident tha~ the Dlicroproces3~r flow chart thus described accompli~he~ the ~arlous fu~ctions a~cribed tc the miaroproce~sor in the task seguence de3cribed in conjunction with ~ig. 1~0. Variations within the task sequence cas~ produce like vari2~tion~ ln ~he ~icrOprOGæs~or flow cha~t and variat~ons within the flow char'c .

The ~icroprocessor board layout indlcate~ the two ~eparate proces~or3 e~ployed include both master and slave p~o¢~ssor board~. ~he master procescor is in c~arge o~
handling operator ~nput and the per~i3ion of the ~achine or ~afety, ~on~urrency with the printer, concurrency with the o~erator and communication with the slave processor. The safety functions ~onilor temperature, pressure, safety gates, emergency stop switch, a~d the condition of t~e shared MULTI~S. The alave p~o~essor controls the rest of the in~ection and recharg~ cycle~ of the equipment along ~ith the three extruders and does thiq o~ a multi-ta~k system basis ~ith a 10 milli~econd ~lock ~or ptoduc ion of error me sages. The sla~e proc~ssor produces pointers to error messag~ which are transmitted along the M~L~IBUS to the ma~ter processor ~or relation to the use~.' The ~lave processor also performs the in~ec-tion cycle using the in;ection profile given to it from the master processor. The total amoun-t of memory availahle for controlling the opera-tion of both -the master and slave processors is defined by hexadecimal codes 0000 to FFFF. Referring to Fig. 148, a map showing the location of specific data areas for the memory iLs shown. Along the uppermost axis of Fig. 148, a complete map is shown showing the relation-ship between both master and slave processor memory areas and the area including the shared memory. Along the intermediate axis, a breakdown is shown between addresses FOOO to FFFF showing the relationship between the two sets of memorles for both the master and slave processor in the shared memory area, which contains all the common variables including the profiles, tables and flags used by both processors. A further breakdown from memory location FFOO to FFFF are provided showing that in the area at the upper end of the shared memory the portlon of the memory containing the pre-stored slave math and D to A and A to D
conversion routines are stored. The operating system employed by the master processor includes commercially available RMX-80 , and operating system available from Intel Corporation, a standard ` FORTRAN library and a standard PLM library. The specific tasks are also provided in the master processor as well as data for FORTRAN and PLM programs.

; The system processor 10 in Fig. 141 is a commercially available model 5TI process controller available from Texas Instrwnents. The ladder diagram is a conventional form of illustration of operation of the process controller and indicates ~ 30 in terms of sequences of operation the interrelationship between the system processor and the in;ection controlling microprocessor including the handoff interrelationship between the two units as was described in greater detail above.

*Trademark ,

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An apparatus for a multi-layer injection molding machine, which comprises a co-injection nozzle having a gate at one end, a central channel in communication with the gate, at least three polymeric melt material flow stream passageways in communication with the central channel, each passageway having an associated orifice whereat the passageway communicates with the central channel, wherein the first of said orifices is more prox-imate the gate than said other orifices, the third of said ori-fices is operative at a position more remote from the gate than said first orifice, and the second of said orifices is located between the first and third orifices, and valve means moveable in the co-injection nozzle central channel, operative with respect to said orifices and adapted to block and unblock and prevent and allow the flow of polymeric melt material through the orifices into said central channel, said valve means being adapted to in one position block said second orifice while it does not block the first or third orifice or both the first and third orifices.

2. The apparatus of claim 1, wherein the valve means is also adapted to, in another position, block the first orifice and not block the third orifice.

3. The apparatus of claim 1, wherein the valve means is also adapted to, in another position block neither the second orifice nor the first orifice.

4. The apparatus of claim 1, wherein the valve means is also adapted to, in one position block the second orifice while all other orifices are not blocked, and in another position block all orifices except the second orifice.

5. The apparatus of claim 1, wherein there is also included means removed from the co-injection nozzle for moving polymeric melt material to each of the nozzle passageways, and for reducing the flow of polymeric material through -the third orifice while the valve means is in said position wherein neither the second nor the third orifice is blocked.

6. An apparatus for a multi-layer injection molding machine, which comprises a co-injection nozzle having a gate at one end, a central channel in communication with the gate, at least three polymeric melt material flow stream passageways in communication with the central channel, each passageway having an associated orifice whereat the passageway communicates with the central channel, wherein the first of said orifices is more prox-imate with the gate than said other orifices, the third of said orifices is operative at a position more remote from the gate than said first orifice, and the second of said orifices is located between the first and third orifices, and valve means axially moveable in the co-injection nozzle central channel, operative with respect to said orifices and adapted to block and unblock and prevent and allow the flow of polymeric melt material through the orifices into said central channel, said valve means being adapted to in one position block said second orifice and not block the third or both the first and third orifices, and in a second position block the first orifice while it blocks neither the second nor the third orifice.

7. The apparatus of claim 6, wherein the valve means is also adapted to, in one position block the second orifice while all other orifices are not blocked, and in another position block all orifices except the second orifice.

8. The apparatus of claim 6, wherein the apparatus also includes means removed from the co-injection nozzle for mov-ing polymeric melt material to each of the nozzle passageways and for reducing the flow of polymeric material through the third orifice while the valve means is in said second position.

9. Co-injection nozzle means for a multi-coinjection nozzle multi-polymer injection molding machine comprising a co-injection nozzle having a gate and a central channel in communi-cation with the gate, at least first and second narrow annular passageway orifices, the first being more proximate the gate than any other passageway orifice, each of the first and second ori-fices being in communication with the central channel, and a third orifice in communication with the central channel and remote from the gate, and valve means in cooperative association with the nozzle central channel and orifices, said valve means including an elongated sleeve having an open end, a cylindrical side wall with a port therein and an elongated cylindrical axial central passageway in communication with the port and the open end, said sleeve being mounted within the nozzle central channel in a close tolerance slip fit in the area of the orifice most proximate the gate, and sufficient to prevent a significant accu-mulation or passage or polymeric material therebetween, with the exception of in said orifices, and an elongated pin mounted within the sleeve central passageway and having a side wall outer surface in a close tolerance slip fit within the central passage-way of the sleeve and sufficient to prevent a significant accumu-lation or passage of melt material between the pin side wall outer surface and the sleeve central passageway wall, said sleeve being adapted to reciprocate axially within the nozzle central channel and operative to block and unblock said first and second orifices and to bring its port into and out of alignment with said third orifice, and said pin being adapted to reciprocate axially within said sleeve to block and unblock said port when it is aligned with said third orifice.

10. The nozzle means of claim 9, wherein the third ori-fice is adapted to flow the polymeric material which is to form the core of a substantially co-axial substantially concentric combined stream of polymer materials through the nozzle central channel, and the sleeve and pin are adapted to be positioned and to cooperate to permit polymeric material to flow through said third orifice while said valve means prevent polymeric material from flowing through said second orifice.

11. The nozzle means of claim 9, wherein said sleeve and pin are also adapted to be positioned and to cooperate to allow polymer material to flow through said second orifice while they prevent material from flowing through said third orifice.

12. The nozzle means of claim 10, wherein said sleeve and pin are also adapted to be positioned and to co-operate to allow polymer material to flow through said second orifice while they prevent material from flowing through said third orifice.

13. Co-injection nozzle means, comprising (a) a co-injection nozzle having a central channel with an open end and a gate at the open end, at least first, second and third pass-ageways each having an orifice defined by leading and trailing lips and communicating with said channel, said lips communicating with the channel in a completely enclosing 360° manner and each orifice having its respective center line substantially perpendi-cular to the axis of the central channel, and second orifice being axially-aligned intermediate the first and third orifices, and (b) valve means axially and reciprocably mounted within said central channel and cooperatively associated therewith, said valving means being adapted and positionable to block all of said orifices, then while said second orifice is blocked, allow poly-mer material to flow from the third orifice into the central channel as a solid stream when viewed in cross-section, then unblock the first orifice to provide a flow of material which completely surrounds the first solid flow stream of two materials when viewed in cross-section, unblock the second orifice to allow polymeric material to flow therethrough and between said earlier flowing two materials and thereby provide a combined stream of three concentric layers, and said valve means also being adapted and positionable to block the flow of the respective materials through the orifices in a sequence which is not the reverse of the introductory sequence.

14. The co-injection nozzle of claim 13, wherein the valve means is adapted to clear the combined stream of three materials from the central channel at the end of the injection cycle at least up to the passage way orifice most proximate the gate.

15. The co-injection nozzle of claim 13, wherein the first and second passageway orifices are sufficiently narrow rel-ative to, and each have an axial width which is uniform about the central channel and less than the cross-sectional width of the central channel, and said passageways and orifices being as close as possible to each other and to the gate to provide minimum flow travel distance and time loss in transferring the combined stream of three materials from the central channel to the gate.

16. The co-injection nozzle of claim 15, wherein the second orifice has leading and trailing lips and the distance of the trailing lip of the second orifice to the gate is from about 100 to about 600 mils.

17. The co-injection nozzle of claim 13, wherein the valve means includes an elongated sleeve having an open end, a cylindrical side wall with a port therein and an elongated cylin-drical axial central passageway in communication with the port and the open end, said sleeve being mounted within the nozzle central channel in a close tolerance slip fit in the area of the orifice most proximate the gate, and sufficient to prevent a sig-nificant accumulation or passage of polymeric material therebe-tween, with the exception of in said orifices, and an elongated pin mounted within the sleeve central passageway and having a side wall outer surface in a close tolerance slip fit within the central passageway of the sleeve and sufficient to prevent a sig-nificant accumulation or passage of melt material between the pin side wall outer surface and the sleeve central passageway wall, said sleeve being adapted to reciprocate axially within the nozzle central channel and operative to block and unblock said first and second orifices and to bring its port into and out of alignment with said third orifice, and said pin being adapted to reciprocate axially within said sleeve to block and unblock said port when it is aligned with said third orifice.

18. Co-injection nozzle means for a multi-coinjection nozzle injection molding machine, comprising, a co-injection nozzle having a central channel having a open end, a gate at the open end, a plurality of polymer stream passageways each having an orifice which communicates with the channel at least the first and second of the orifices doing so in a completely surrounding 360° manner and having a leading lip, wherein the leading lip of each orifice and the center line of each orifice each lie sub-stantially perpendicular to the axis of the central channel, the first passageway orifice being the orifice most proximate the gate, the third passageway orifice being least proximate to the gate, and the second passageway orifice being intermediate the first and third orifices, the area of the central channel encom-passed by the first and second orifices being a combined area for combining polymer streams, each of said passageway orifices hav-ing a cross-sectional area no greater than the cross-sectional area of the channel, and each of said first and intermediate ori-fices being as close as possible to each other and to the gate to permit minimum flow travel distance of combined material flow from said passageway orifices to the gate, and valve means com-prised of an elongated sleeve seated in a close slip tolerance fit within and axially reciprocable within said channel, said sleeve having an open end which, when the sleeve it in its for-wardmost position, is aligned with and communicates with the gate and having a side wall with a port therein said port being adapted to communicate with the third passageway orifice, and an elongated pin mounted in a close tolerance slip fit within said sleeve and adapted for reciprocable movement therewithin, said pin having a side wall and a closed forward end and being move-able to a position which closes said port and being cooperative with said sleeve when they are in a forward position, to substan-tially completely purge the combining area of said channel, said channel, sleeve and pin having no reservoir between their side walls other than said port wherein material in transit from any passageway to the gate can accumulate, said valve means being moveable to respective positions whereat all orifices are blocked, all orifices are opened, only the first orifice is unblocked, only the third orifice is unblocked, and only the first and second are unblocked.

19. The co-injection nozzle means of claim 18, wherein the nozzle means includes drive means for driving said valve means to said positions.

20. The co-injection nozzle means of claim 18, wherein said valve means are adapted to unblock all orifices within a period of about 75 centiseconds.

21. The co-injection nozzle means of claim 20, wherein said valve means are adapted to unblock all orifices within a period of about 75 centiseconds.

22. The co-injection nozzle means of claim 20, wherein said valve means are adapted to unblock all orifices within a period of about 20 centiseconds.

23. The co-injection nozzle means of claim 20, wherein said valve means are adapted to unblock all orifices within a period of about 15 centiseconds.

24. The co-injection nozzle means of claim 18, wherein the central central channel has a uniform cross-sectional area at least from the first passageway orifice to the second passageway orifice.

25. The co-injection nozzle means of claim 18, wherein the passageway having the first orifice has a leading wall which extends diagonally towards the gate and towards the axis of the central channel and communicates with the leading lip of the first orifice, such that the leading lip of the first orifice is closer to the axis of the central channel than the trailing lip of said orifice and wherein the sleeve wall has a tapered mouth which defines the sleeve open end and is adapted to abut against said leading wall to prevent further forward movement of the sleeve in the central channel toward the gate and to block said first orifice.

26. Co-injection nozzle means comprised of, a co-injec-tion nozzle having a central channel, having an open end, a gate at the open end, at least three passageways each having an ori-fice which communicates with the central channel in a completely enclosing 360° manner and having the leading edge of each orifice and the center line for each orifice perpendicular to the axis of the central channel, the first passageway orifice being most proximate the gate, the third passageway orifice being least proximate the gate, and the second passageway orifice being intermediate the first and third orifices, and valve means com-prised of an elongated sleeve seated in a close tolerance slip fit within and being axially reciprocable within the central channel, having a central passageway, a forward open end which is adapted to communicate with a portion of the central channel located between the first and second orifices, and having a wall with a port therein adapted to communicate with the third pas-sageway orifice and to block and unblock the third passageway orifice, and said sleeve being capable of axial movement to a position at which it at the same time blocks the first and second passageway orifices while said port is aligned with the third passageway orifice and is not blocked, means for blocking the port when the third passageway orifice and port are in communica-tion, said means being such that at the same time the first and second orifices are not blocked by the sleeve, the port is blocked by the port blocking means, and such that when the port is not blocked by the blocking means and is aligned with the third orifice.

27. The co-injection nozzle means of claim 26, wherein said sleeve is also adapted to be in a position wherein the first and second orifices are unblocked, while the third orifice is closed by the third orifice blocking means, and to a position wherein all orifices are at the same time blocked~

28. The co-injection nozzle means of claim 26, wherein the sleeve has a rear end portion and the means for blocking the port is a stationary member extending within a rear end portion of the sleeve central passageway to partially block the third orifice, said member having an outer wall surface which is in a close tolerance slip fit within the sleeve central passageway and being cooperative with the sleeve such that when the sleeve is withdrawn from a forward position, the sleeve port is aligned with the third orifice but is juxtaposed relative to and par-tially blocked by the member.

29. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being car-ried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said ori-fices and to bring said internal axial passageway into and out of communication with said nozzle passageway, and, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth, and sixth positions, wherein in said first position the sleeve mean blocks all of the exit orifices and said internal axial passageway is out of commu-nication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial pas-sageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passage-way is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two ori-fices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proxi-mate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pas-sageway.

30. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means, and means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway.

31. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means, and wherein the sleeve means is adapted for one or both of axial movement in the central channel of the nozzle or rotational movement in said channel whereby said sleeve, when moved therein to selected positions, block and unblocks one or more of said orifices and brings said aperture into and out of alignment with said nozzle passageway, and means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the, open end of said nozzle central channel, and said axial passage-way is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two ori-fices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proxi-mate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway.

32. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal material flow passage-way communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, and being moveable to a selected position to block and unblock at least two of said orifices, and means to actuate the sleeve means to a position selected from the group consisting of first, sec-ond, third, forth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to -the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of com-munication with said nozzle passageway, and in said sixth posi-tion the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway.

33. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, and means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of commu-nication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial pas-sageway is in communication with said nozzle passagewag, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passage-way is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pass-ageway.

34. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means, and means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pass-ageway.

35. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means, and wherein the sleeve means is adapted for one or both of axial movement in the central channel of the nozzle or rotational move-ment in said channel whereby said sleeve, when moved therein to selected positions, blocks and unblocks one or more of said ori-fices and brings said aperture into and out of alignment with said nozzle passageway, and means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said axial passageway is in communi-cation with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial pas-sageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passage-way is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two ori-fices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proxi-mate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pas-sageway.

36. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel, being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, and being moveable to a selected position to block and unblock at least two of said orifices, and means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not: block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway.

37. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block a-t least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of com-munication with said nozzle passageway, and in said sixth posi-tion the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, the actuating means being operative to move the sleeve means sequentially from said first position to each of said second through sixth positions and then to said first position.

38. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, wherein said five material streams are controlled.

39. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle had a central open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway com-municating with the nozzle central channel and adapted to commu-nicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communi-cation with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, wherein said five material streams are controlled.

40. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to -the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein the communication from the internal axial passageway of the sleeve means to said one passageway in the nozzle is through an aperture in the wall of the sleeve means, wherein the sleeve means is adapted for one or both of axial movement in the central channel of the nozzle or rotational move-ment in said channel whereby said sleeve, when moved therein to selected positions, blocks and unblocks one or more of said ori-fices and brings said aperture into and out of alignment with said nozzle passageway, means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle pas-sageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle pas-sageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, wherein said five material streams are controlled.

41. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal passageway into and out of communication with said nozzle pas-sageway, wherein said sleeve means is moveable to a selected position to block and unblock at least two of said orifices, and means to actuate the sleeve means to a selected one of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said internal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is out of communication with said nozzle passageway, in said third posi-tion the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least -two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proxi-mate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pas-sageway, wherein said five streams are controlled.

42. An apparatus for selectively con-trolling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of com-munication with said nozzle passageway, and in said sixth posi-tion the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, wherein five said material streams are controlled and actuating means is operable to move the sleeve means sequentially from said first position to each of said second through sixth positions and then to said first position.

43. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding mutli-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position, the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of com-munication with said nozzle passageway, and in said sixth posi-tion the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway, wherein five material streams are controlled, wherein the nozzle includes four exit orifices communicating with the nozzle central channel and wherein the sleeve means includes one internal mate-rial flow passageway and has one aperture in the wall thereof.

44. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, wherein five material streams are controlled, wherein the nozzle includes three exit orifices communicating with the nozzle central channel and wherein the sleeve means includes two material flow passageways and has two apertures in the wall thereof each communicating with said nozzle passageways.

45. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the melt materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axial passageway is out of communication with said nozzle passageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communica-tion with said nozzle passageway, in said third position the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with said nozzle passageway, in said fourth position the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in com-munication with said nozzle passageway, in said fifth position the sleeve means does no-t block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means does not block the orifice most proxi-mate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle pas-sageway, wherein five material streams are controlled, wherein the nozzle includes three exit orifices communicating with the nozzle central channel and wherein the sleeve means includes two internal material flow passageways and has two apertures in the wall thereof each communicating with said nozzle passageways.

46. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, and pin means moveable in the axial pas-sageway of the sleeve means to selected positions to interrupt and restore communication between said internal axial passageway and said nozzle passageway.

47. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding multi-layer plastic articles from the materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminat-ing at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial material flow passageway communicating with the nozzle central channel and adapted to communicate with a flow passageway exterior of the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, and pin means moveable in the axial passageway of the sleeve means to selected positions to interrupt and restore communication between said internal axial passageway and said exterior passageway.

48. The apparatus of claim 46, wherein the communica-tion from the internal passageway of the sleeve means to the pas-sageway in the nozzle is through an aperture in the wall of the sleeve means.

49. The apparatus of claim 45, wherein the communica-tion from the internal axial passageway of the sleeve means to the exterior passageway is through an aperture in the wall of the sleeve means.

50. The apparatus of claim 46 further comprising means to actuate the sleeve means and the pin means to a mode selected from the group consisting of first, second, third, fourth, fifth and sixth modes, wherein in said first mode the sleeve means blocks all of the exit orifices and the pin means blocks communi-cation between said internal axial passageway and said nozzle passageway, in said second mode the sleeve means blocks all of the exit orifices and the pin means establishes communication between said axial passageway and said nozzle passageway, in said third mode the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and the pin means establishes communication between said axial passageway and said nozzle passageway, in said fourth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means establishes communication between said axial passageway and said nozzle passageway, in said fifth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means blocks communication between said axial passageway and said nozzle passageway, and in said sixth mode the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and the pin means blocks communication between said axial passageway and said nozzle passageway.

51. The apparatus of claim 46 further comprising means to actuate the sleeve means and the pin means to a selected one of first, second, third, fourth, fifth and sixth modes, wherein in said first mode the sleeve means blocks all of the exit ori-fices and the pin means blocks communication between said inter-nal axial passageway and said nozzle passageway, in said second mode the sleeve means blocks all of the exit orifices and the pin means establishes communication between said axial passageway and said nozzle passageway, in said third mode the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and the pin means establishes communication between said axial passageway and said nozzle passageway, in said fourth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means establishes communica-tion between said axial passageway and said nozzle passageway, in said fifth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means blocks communication between said axial passageway and said nozzle passageway, and in said sixth mode the sleeve means unblocks the orifice most proxi-mate to the open end of the nozzle central channel and the pin means blocks communication between said axial passageway and said nozzle passageway.

52. The apparatus of claim 50, in which the actuating means is operative to move the sleeve means and the pin means sequentially from said first mode to each of said second through sixth modes and then to said first mode.

53. The apparatus of claim 46, wherein five material streams are controlled.

54. The apparatus of claim 48, wherein five material streams are controlled.

55. The apparatus of claim 50, wherein five material streams are controlled.

56. The apparatus of claim 52, wherein five material streams are controlled.

57. The apparatus of claim 53, wherein the nozzle includes four exit orifices communicating with the nozzle central channel and wherein the sleeve means has one internal flow pas-sageway and one aperture in the wall thereof.

58. The apparatus of claim 50, wherein one end of the pin means is proximate to the open end of the nozzle central channel when the sleeve means and the pin means are in said first mode.

59. The apparatus of claim 51, wherein one end of the pin means is proximate to the open end of the nozzle central channel when the sleeve means and the pin means are in said first mode.

60. The apparatus of claim 52, wherein one end of the pin means is proximate to the open end of the nozzle central channel when the sleeve means and the pin means are in said first mode.

61. The apparatus of claim 46, wherein five material streams are controlled, wherein the nozzle includes four exit orifices communicating with the nozzle central channel and wherein the sleeve means includes one internal flow passageway and has one aperture in the wall thereof.

62. The apparatus of claim 50, wherein five material streams are controlled, wherein the nozzle includes four exit orifices communicating with the nozzle central channel and wherein the sleeve means includes one internal flow passageway and has one aperture in the wall thereof.

63. The apparatus of claim 46, wherein five material streams are controlled, wherein the nozzle includes three exit orifices communicating with the nozzle central channel and wherein the sleeve means includes two internal flow passageways and has two apertures in the wall thereof each communicating with said nozzle passageways.

64. The apparatus of claim 50, wherein five material streams are controlled, wherein the nozzle includes three exit orifices communicating with the nozzle central channel and wherein the sleeve means includes two internal flow passageways and has two apertures in the wall thereof each communicating with said nozzle passageways.

65. The apparatus of claim 46 further comprising mate-rial flow directing means associated with the nozzle for balanc-ing the flow of at least one material stream around the nozzle passageway and exit orifice through which the stream flows.

66. The apparatus of claim 46, wherein at least two of the exit orifices are located close to each other and to the open end of the nozzle central channel.

67. The apparatus of claim 46 further comprising means for pressurizing at least one material stream.

68. The apparatus of claim 46 further comprising mate-rial flow directing means in at least one of said nozzle passage-ways for balancing the flow of at least one material stream around said passageway and the exit orifice through which it flows, and means for pressurizing said stream to produce a pres-surized reservoir of material in said nozzle passageway between said flow directing means and said orifice, whereby, when the sleeve means unblocks said orifice, the start of flow of said material through said orifice is substantially uniform around the orifice.

69. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding very thin wall multi-layer plastic articles from the materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle pas-sageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve means being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring said internal axial passageway into and out of communication with said nozzle passageway, and means to actuate the sleeve means to a position selected from the group consisting of first, second, third, fourth, fifth and sixth positions, wherein in said first position the sleeve means blocks all of the exit orifices and said inter-nal axis passageway is out of communication with said nozzle pas-sageway, in said second position the sleeve means blocks all of the exit orifices and said axial passageway is in communication with said nozzle passageway, in said third position the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communica-tion with said nozzle passageway, in said fourth position the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with said nozzle passageway, in said fifth position the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with said nozzle passageway, and in said sixth position the sleeve means unblocks the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with said nozzle passageway.

70. The apparatus of claim 69, wherein there are four passageways with orifices communicating with the central channel at locations close to the open end.

71. The apparatus of claim 69, wherein the article is a container having a side wall whose total thickness is from about 0.010 to about 0.035 inch.

72. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for injection molding very thin wall multi-layer plastic articles from the materials, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle pas-sageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, pin means moveable in the axial pas-sageway of the sleeve means to selected positions to block and establishes communication between said internal axial passageway and said nozzle passageway, and means to actuate the sleeve means and the pin means to a mode selected from the group consisting of first, second, third, fourth, fifth and sixth modes, wherein in said first mode the sleeve means blocks communication between said internal axial passageway and said nozzle passageway, in said second mode the sleeve means blocks all of the exit orifices and the pin means establishes communication between said axial passageway and said nozzle passageway, in said third mode the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and the pin means establishes com-munication between said axial passageway and said nozzle passage-way, in said fourth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means establishes communication between said axial passageway and said nozzle pas-sageway, in said fifth mode the sleeve means unblocks at least two orifices, one of which is the orifice most proximate to the open end of the nozzle central channel, and the pin means blocks communication between said axial passageway and said nozzle pas-sageway, and in said sixth mode the sleeve means unblocks the orifices most proximate to the open end of the nozzle central channel, and the pin means blocks communication between said axial passageway and said nozzle passageway, and in said sixth mode the sleeve means unblocks the orifice most proximate to the open end of the nozzle central channel and the pin means blocks communication between said axial passageway and said nozzle pas-sageway.

73. The apparatus of claim 72, wherein there are four passageways with orifices communicating with the central channel at locations close to the open end.

74. The apparatus of claim 72, wherein the article is a container having a side wall whose total thickness is from about 0.010 to about 0.035 inch.

75. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for co-injecting the materials into a cavity to form thin wall multi-layer plastic articles having at least one thin inter-nal layer, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve being car-ried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said ori-fices, pin means moveable in the axial passageway of the sleeve means to selected positions to block and establish communication between said internal axial passageway and said nozzle passage-way, and material flow direction means associated with the nozzle for balancing the flow of the material stream which forms said internal layer around the nozzle passageway and exit orifice through which said stream flows, whereby the location of the ter-minal end of said internal layer is substantially uniform in the injected article at the conclusion of polymer movement in said injection cavity.

76. The apparatus of claim 75 further comprising means for pressurizing at least the internal layer material stream.

77. The apparatus of claim 75, wherein the material flow directing means is located in the nozzle passageway for the flow stream of the material which forms said internal layer, and further comprising means for pressurizing said stream to produce a pressurized reservoir of material in said nozzle passageway between said flow directing means and said orifice, whereby, when the sleeve means unblocks said orifice, the start of flow of said material through said orifice is substantially uniform around the orifice.

78. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for co-injecting the materials into a cavity to form thin wall multi-layer plastic articles having an outer layer, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminating at an exit orifice, each of said orifices communicating with the nozzle central chan-nel at locations close to the open end, sleeve means having at least one outer axial flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, pin means moveable in the axial passageway of the sleeve means to selected positions to block and establish communication between said outer axial passageway and said nozzle passageway, and material flow directing means associated with the nozzle for balancing the flow of the material stream which forms said outer layer around the nozzle passageway and exit orifice through which said stream flows, whereby the location of the terminal end of said outer layer is substantially uniform in the injected article at the conclusion of polymer movement in said injection cavity.

79. The apparatus of claim 78 further comprising means for pressurizing a-t least the outer layer material stream.

80. The apparatus of claim 75, wherein the material flow directing means is located in the nozzle passageway for the flow stream of the material which forms said outer layer, and further comprising means for pressurizing said stream to produce a pressurized reservoir of material in said nozzle passageway between said flow directing means and said orifice, whereby, when the sleeve means unblocks said orifice, the start of flow of said material through said orifice is substantially uniform around the orifice.

81. An apparatus for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for co-injecting the materials into a cavity to form thin wall multi-layer plastic articles having an outer layer and at least one thin internal layer, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle pas-sageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial flow passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, pin means moveable in the axial pas-sageway of the sleeve means to selected positions to block and establish communication between said internal axial passageway and said nozzle passageway, and material flow directing means associated with the nozzle for balancing the flows of the material streams which form said outer layer and the internal layer around the respective nozzle passageway and exit orifices through which said streams flow, whereby the locations of the terminal ends of said outer layer and said internal layer are substantially uniform in the injected article at the conclusion of polymer movements in said injection cavity.

82. The apparatus of claim 81, wherein said nozzle pas-sageways for the flow streams which form the outer layer and internal layer are tapered such that they each have a wide gap remote from their associated orifices and have a narrow gap at the orifices.

83. The apparatus of claim 81 further comprising means for pressurizing the outer layer and internal layer polymer streams.

84. The apparatus of claim 81, wherein the material flow directing means is located in the respective nozzle passage-ways for the flow streams of the materials which form said outer and internal layers, and further comprising means for pressuriz-ing said streams to produce a pressurized reservoir of material in each of said nozzle passageways between said flow directing means and said orifices, whereby, when the sleeve means unblocks said orifices, the starts of flow of said materials through said orifices are substantially uniform around the orifices.

85. Co-injection nozzle means for a multi-polymer injection molding machine for co-injecting at least three streams of melt materials to form a multi-layer article therefrom, which comprises a co-injection nozzle having an axially central chan-nel, a gate in communication with the central channel, at least three polymer stream passageways each having an annular orifice, the first of said orifices being proximate the gate, the second of said orifices being adjacent the first orifice, and the third of said orifices being more remote from the gate than said other orifices, wherein at least the first or second passageway has a tapered portion adjacent its respective orifice such that each orifice has a smaller cross-sectional gap than an upstream adja-cent portion of its respective passageway, and valve means opera-tive in the central channel for blocking and unblocking the ori-fices and adapted to in one position block the second orifice while the third orifice is not blocked by said valve means.

86. Co-injection nozzle means for a multi-polymer injection molding machine for co-injecting at least three streams of melt materials to form a multi-layer article therefrom, which comprises a co-injection nozzle having an axially extending cen-tral channel, a gate in communication with the central channel, at least three polymer stream passageways each having an annular orifice, the first of said orifices being proximate the gate, the second of said orifices being adjacent the first orifice, and the third of said orifices being more remote from the gate than said other orifices, wherein each of the first and second passageways has a tapered portion adjacent its respective orifice such that each orifice has a smaller cross-sectional gap than an upstream adjacent portion of its respective passageway, and valve means operative in the central channel for blocking and unblocking the orifices and adapted to in one position block the second orifice while the third orifice is not blocked by the valve means.

87. The co-injection nozzle means of claim 86, wherein the valve means is also adapted to in another position block the third orifice while the first orifice is not blocked by the valve means.

88. The co-injection nozzle means of claim 86 or 87, wherein the valve means includes a sleeve having a central axial passageway, an open end in communication with the axial passage-way and a port in the sleeve wall, and an elongated pin axially moveable within the sleeve and adapted to block and unblock said port.

89. Co-injection nozzle means for a multi-polymer injection molding machine for co-injecting at least three streams of melt materials to form a multi-layer article therefrom, which comprises a co-injection nozzle having an axially extending cen-tral channel, a gate in communication with the central channel, and five polymer stream passageways each having an annular ori-fice, the first of said orifices begin proximate the gate, the second of said orifices being adjacent the first orifice, and the third of said orifices being more remote from the gate than said other orifices, the fourth orifice being intermediate the first and second orifices, and the fifth orifice being intermediate the second and third orifices, wherein at least the first or second passageway has a tapered portion adjacent its respective orifice such that each orifice has a smaller cross-sectional gap than an upstream adjacent portion of its respective passageway, and valve means operative in the central channel for blocking and unblock-ing the orifices and adapted to block the second orifice while the third orifice is not blocked by the valve means.

90. An apparatus for use in a multi-coinjection nozzle injection molding machine for injection molding a multi-layer plastic article, which comprises co-injection nozzle means for co-injecting at least three streams of melt materials to form the multi-layer article therefrom, said co-injection nozzle means having an axially extending central channel, a gate in communica-tion with the central channel, at least three polymer stream pas-sageways each having an annular orifice, the first of said ori-fices being proximate the gate, the second of said orifices being adjacent the first orifice, and the third of said orifices being more remote from the gate than said other orifices, wherein at least the first or second passageway has a tapered portion adja-cent its respective orifice such that each orifice has a smaller cross-sectional gap than an upstream adjacent portion of its respective passageway, valve means operative in the central chan-nel for blocking and unblocking the orifices, and, means for dis-placing polymer melt material through each passageway and pas-sageway orifice, and for pressurizing a melt material in a tapered passageway while its orifice is blocked by the valve means, wherein for each material stream there is a means for dis-placing and pressurizing melt material, and each means is adapted to pressurize the melt material in its passageway while its pas-sageway orifice is blocked by said valve means, and wherein the valve means is adapted to in one position block the second ori-fice while the third orifice is not blocked by the valve means.

91. An apparatus for use in a multi-coinjection nozzle injection molding machine for injection molding a multi-layer plastic article, which comprises co-injection nozzle means for co-injecting at least three streams of melt materials to form the multi-layer articles -therefrom, said co-injection nozzle means having an axially extending central channel, a gate in communica-tion with the central channel, fine polymer stream passageways each having an annular orifice, the first of said orifices being proximate the gate, the second of said orifices being adjacent the first orifice, and the third of said orifices being more remote from the gate than said other orifices, wherein each of the first, second, fourth and fifth passageways has a tapered portion adjacent its respective orifice such that each orifice has a smaller cross-sectional gap than an upstream adjacent por-tion of its respective passageway, valve means operative in the central channel for blocking and unblocking the orifices and adapted to block the fourth, second and fifth orifices while the third orifice is not blocked by the valve means, and means for displacing polymer melt material through each passageway and pas-sageway orifice, and for pressurizing the melt material in each tapered passageway while its orifice is blocked by the valve means.

92. The co-injection nozzle means of claim 91, wherein there is included means in cooperative association with each tapered passageway for balancing the flow of melt material through each of said tapered passageways.

93. Co-injection nozzle means for co-injecting a five layer plastic article, which comprises a co-injection nozzle hav-ing an open end, a gate at -the open end, a cylindrical central channel in communication with the gate, and five polymer flow stream passageways, each having an orifice in communication with the central channel and each adapted for passing a melt flow stream of polymeric material through -the orifice into the central channel for forming a layer of the article, there being a first passageway more proximate to the gate than any other orifice, for passing a melt stream of structural material into the central channel for forming the outside surface layer of the article, a second internal passageway for passing a melt stream of material into the central channel for forming an internal layer of the article, a third passageway more remote from the gate than any other orifice for passing a melt stream of structural material into the central channel for forming the inside surface layer of the article, a fourth passageway between the first and second passageways for passing a melt stream of polymeric material into the central channel for forming an intermediate layer between the outside surface layer and the internal layer of the article, and a fifth passageway between the second passageway and the third passageway for passing a melt stream of material into the central channel for forming an intermediate layer between the internal layer and the inside surface layer of the article, and, valve means in cooperative association with the nozzle and operative adjacent at least the second orifice and the third orifice and adapted to, at the same time, block the second orifice and not block the third orifice.

94. The co-injection nozzle means of claim 93, wherein the valve means includes an elongated sleeve having an open end, a cylindrical side wall with a port therein, and an elongated axial central passageway in communication with the port and the open end, said sleeve being mounted within the nozzle central channel in close tolerance slip fit sufficient to prevent, with the exception of in said orifices, a significant accumulation or passage of polymeric material therebetween, and an elongated pin mounted within the sleeve central passageway and having a side wall outer surface in a close tolerance slip fit within the cen-tral passageway of the sleeve and sufficient to prevent a signif-icant accumulation or passage of melt material between the pin side wall outer surface and the sleeve central passageway wall, said sleeve being adapted to reciprocate axially within the nozzle central channel and operative to block and unblock said first and second orifices and to bring its port into and out of alignment with said remote orifice, and said pin being adapted to reciprocate axially within said sleeve to block and unblock said port when it is aligned with said remote orifice.

95. The co-injection nozzle means of claim 93, wherein the valve means is operative with respect to at least three of the five orifices, and said valve means is also adapted to block said second orifice while said valve means does not block the first and third orifices.

96. The co-injection nozzle of claim 93, wherein the valve means is operative with respect to all five of the orifices and is adapted to block the second, fourth and fifth orifices while said valve means does not block the third orifice.

97. The co-injection nozzle of claim 96, wherein the valve means is adapted to at the same time block the second ori-fice while said valve means does not block the first orifice, the third orifice, or both the first and third orifices.

98. The method of claim 96, wherein the axial distance between the leading lip of the fourth orifice and the trailing lip of the fifth orifice is from about 100 to about 900 mils.

99. The method of claim 96, wherein the axial distance between the leading lip of the fourth orifice and the trailing lip of the fifth orifice is from about 100 to about 300 mils.

100. The co-injection nozzle means of claim 96, wherein the first, second, fourth and fifth nozzle passageways are tapered towards their respective orifices such that each tapered passageway has a greater gap at an adjacent location remote from the orifice and a shorter gap at the orifice.

101. Co-injection nozzle means for co-injecting a five layer plastic article, which comprises a co-injection nozzle hav-ing an open end, a gate at the open end, a cylindrical central channel in communication with the gate, and five polymer flow stream passageways, each having an orifice in communication with the central channel and each adapted for passing a melt flow stream of polymeric material through the orifice into the central channel for forming a layer of the article, there being a first passageway more proximate to the gate than any other orifice for passing a melt stream of structural material into the central channel for forming the outside surface layer of the article, a second internal passageway for passing a melt stream of material into the central channel for forming an internal layer of the article, a third passageway more remote from the gate than the other orifices for passing a melt stream of structural material into the central channel for forming the inside surface layer of the article, a fourth passageway between the first and second passageways for passing a melt stream of polymeric material into the central channel for forming an intermediate layer between the outer surface layer and the internal layer of the article, and a fifth passageway between the internal passageway and the third passageway for passing a melt stream of material into the central channel for forming an intermediate layer between the internal layer and the inside surface layer of the article, wherein the first, second, fourth, and fifth nozzle passageways are tapered towards their respective orifices such that each tapered passage-way has a greater gap at an adjacent location remote from the orifice and a shorter gap at the orifice, and, valve means in cooperative association with the nozzle and operative adjacent and with respect to at least the second orifice and the third orifice and adapted to at the same time block the second orifice and not block the third orifice.

102. Co-injection nozzle means for a multi-polymer injection blow molding machine for co-injecting at least three streams of melt materials to form a multi-layer article there-from, which comprises a co-injection nozzle having a cylindrical central channel open at one end, a gate at the open end and in communication with the central channel, at least two passageways each having an annular orifice close to the gate and in communi-cation with the central channel, and a third passageway having an orifice remote from the gate and in communication with the cen-tral channel, the first of said at least two orifices being prox-imate the gate and the second of said at least two orifices being adjacent to and proximate the first orifice, each of said ori-fices having its center line in a plane substantially perpendicu-lar to the axis of the central channel and said orifices being defined by a leading lip close to the open end and a trailing lip remote from the open end, said central channel having two cylin-drical portions, the first portion extending from the gate to the leading lip of the first orifice, and the second portion extend-ing from the trailing lip of the first orifice in a direction axially upstream to at least the trailing lip of the second ori-fice, said first portion being of a shorter diameter than said second portion, and valve means in cooperative association with the nozzle central channel and orifice, said valve means includ-ing an elongated sleeve having an open end, a cylindrical side wall with a port therein and an elongated central passageway in communication with the port and the open end, said sleeve being mounted within the nozzle central channel in a close tolerance slip fit within the second portion of said central channel and sufficient to prevent a significant accumulation or passage of polymer material therebetween, and adapted to be capable of blocking each of said first and second orifices, an elongated pin mounted within the central passageway of the sleeve and having a side wall outer surface in close tolerance slip fit within the central passageway of the sleeve and sufficient to prevent a sig-nificant accumulation or passage of melt material between the pin outer surface and the sleeve central passageway wall, the outer diameter of said sleeve side wall outer surface being of a diame-ter which provides a close tolerance slip fit within the first portion of the nozzle central channel, said sleeve being adapted to reciprocate axially within the nozzle central channel to block and unblock said first and second orifices and to bring said port into and out of alignment with said third orifice, and to block and unblock said port when the port is aligned with the third orifice and, said valve means being adapted to and capable of i clearing said central channel first portion of polymer melt mate-rial at the end of an injection cycle and to prevent back-up of polymer material into said orifices.

103. The co-injection nozzle means of claim 102 wherein the passageway having the first orifice has a leading wall which extends diagonally towards the gate and towards the axis of the central channel and communicates with the leading lip of the first orifice, such that the leading lip of the first orifice is closer to the axis of the central channel than the trailing lip of said orifice, and wherein the sleeve wall has a tapered mouth which defines the sleeve open end and is adapted to abut against said leading wall to prevent further forward movement of the sleeve in the central channel toward the gate and to block said first orifice.

104. The co-injection nozzle means of claim 103, wherein the pin is adapted to move forwardly into the first cen-tral channel portion.

105. The co-injection nozzle means of claim 102, wherein said valve means are adapted to move forward toward the gate sufficiently to clear the combining area of polymer mate-rial, and said pin and sleeve are adapted such that said pin is capable of being in a position such that its forward end is axi-ally offset upstream from the forward end of the sleeve, and that they together are axially moveable forward through the central channel, said offset position of said pin forward end providing an accumulation area in the forward end of the sleeve for accumu-lation of polymer melt material and for pushing of said material forward through the channel when said channel is cleared by the clearing action of said pin and sleeve.

106. The co-injection nozzle means of claim 103, wherein said valve means are adapted to move forward toward the gate sufficiently to clear the combining area of polymer mate-rial, and said pin and sleeve are adapted such that said pin is capable of being in a position such that its forward end is axi-ally offset upstream from the forward end of the sleeve, and that they together are axially movable forward through the central channel, said offset position of said pin forward end providing an accumulation area in the forward end of the sleeve for accumu-lation of polymer melt material and for pushing of said material forward through the channel when said channel is cleared by the clearing action of said pin and sleeve.

107. The co-injection nozzle means of claim 104, wherein said valve means are adapted to move forward toward the gate sufficiently to clear the combining area of polymer mate-rial, and said pin and sleeve are adapted such that said pin is capable of being in a position such that its forward end is axi-ally offset upstream from the forward end of the sleeve, and that they together are axially moveable forward through the central channel, said offset position of said pin forward end providing an accumulation area in the forward end of the sleeve for accumu-lation of polymer melt material and for pushing of said material forward through the channel when said channel is cleared by the clearing action of said pin and sleeve.

108. Co-injection nozzle means comprised of, a co-injection nozzle having a central channel having an open end, a gate at the open end, at least three passageways each having an orifice which communicates with the central channel in a com-pletely enclosing 360° manner and having the leading edge of each orifice and the center line for each orifice perpendicular to the axis of the central channel, the first passageway orifice being most proximate the gate, the third passageway orifice being least proximate the gate, and the second passageway orifice being intermediate the first and third orifices, wherein the central channel has stepped, cylindrical sections having different diame-ters therein, and valve means comprised of an elongated sleeve seated within and being axially reciprocable within the central channel, having a central passageway, a forward open end which is adapted to communicate with a portion of the central channel located between the first and second orifices, and having an outer surface wall with a port therein adapted to communicate with a passageway orifice remote from the open end of the central channel and to block and unblock said passageway remote from the open end, said wall having radially stepped cylindrical surface portions, each of which is adapted to block one or more of said nozzle passageways when said sleeve is fully seated forward in said central channel, and, an elongated pin mounted within the sleeve central passageway and having a side wall outer surface in a close tolerance slip fit within the central passageway of the sleeve and sufficient to prevent a significant accumulation or passage of melt material between the pin side wall outer surface and the sleeve central passageway wall, and said pin being adapted to reciprocate axially within said sleeve to block and unblock said port when it is aligned with said remote orifice.

109. The co-injection nozzle means of claim 108, wherein the sleeve and the pin are adapted to be positioned and to cooperate such that at the same time the third orifice is not blocked by the valve means while the second orifice is blocked by he valve means.

110. The co-injection nozzle means of claim 108, wherein the co-injection nozzle means includes five nozzle pas-sageways, there being a fourth passageway intermediate the second passageway and the first passageway, and a fifth passageway intermediate the second passageway and the third passageway.

111. The co-injection nozzle means of claim 108, wherein the fourth and fifth passageways communicate with the central channel through the second orifice.

112. The co-injection nozzle means of claim 109, wherein the fourth and fifth passageways communicate with the central channel through the second orifice.

113. The co-injection nozzle means of claim 108, wherein central channel has a combining area extending from the forward lip of the first orifice to the trailing lip of the sec-ond orifice and said combining area has an axial length of from about 100 to about 900 mils.

114. The co-injection nozzle means of claim 111, wherein the central channel has a combining area extending from the forward lip of the first orifice to the trailing lip of the second orifice and said combining area has an axial length of from about 100 to about 900 mils.

115. The co-injection nozzle means of claim 113, wherein the axial length of the combining area is from about 100 to about 300 mils.

116. The co-injection nozzle means of claim 114, wherein the axial length is from about 100 to about 300 mils.

117. The co-injection nozzle means of claim 111, wherein the axial length from the leading lip of the fourth ori-fice to the trailing lip of the fifth orifice is from about 100 to about 900 mils.

118. The co-injection nozzle means of claim 117, wherein the axial length of the combining area is from about 100 to about 300 mils.

119. An apparatus for an injection molding machine, which comprises a co-injection nozzle having a central channel with an open end, a gate at the open end, two polymeric material melt flow stream passageways, each passageway having an orifice in communication with the central channel, a channel for each melt flow stream, one in communication with one passageway, and the other in communication with the other passageway, a common moving means in communication with each passageway for moving both of the polymeric material melt flow streams through their channels, passageways and orifices, and valve means mounted in the central channel and operative to block, partially block and unblock the orifices, said co-injection nozzle having an addi-tional polymeric material melt flow stream passageway with an orifice in communication with the central channel, said addi-tional passageway and orifice being located between the two pas-sageways and orifices, and the valve means is adapted to block said additional orifice while adapted to block said additional orifice while said two orifices are not blocked by the valve means.

120. The apparatus of claim 1 or 90, wherein the valve means is also adapted to in another position block the third ori-fice while it does not block the second orifice.

121. The co-injection nozzle means of claim 85 or 86, wherein the valve means is also adapted to in another position block the third orifice while it does not block the second ori-fice.

122. The co-injection nozzle means of claim 89, 93 or 101, wherein the valve means is also adapted to block the third orifice while it does not block the second orifice.

123. The apparatus of claim 119, wherein the valve means is also adapted to block one or both of the two orifices while it does not block the additional passageway.

124. A nozzle apparatus for injection molding a multi-layer article, characterized by having a gate at one end, and a central channel in communication with the gate, at least three polymeric melt material flow stream passageways in communication with the central channel each through an associated orifice, a first of said orifices being more proximate the gate than the other orifices, and a third of said orifices being disposed more remotely from the gate than the other orifices, and the nozzle apparatus further including valve means moveable in the nozzle central channel and operative to block and unblock the orifices and thereby selectively prevent and allow flow of polymeric melt materials through the orifices into the central channel for injection.

125. The nozzle apparatus according to claim 124, characterized by the valve means being adapted to in one position block said second orifice while it does not block the first or third orifice, or both the first and third orifices.

126. The nozzle apparatus according to claim 125, characterized by the valve means being also adapted in another position to block the first orifice and not block the third orifice.

127. The nozzle apparatus according to claim 125, characterized by the valve means being also adapted in another position to block neither the second orifice nor the first orifice.

128. The nozzle apparatus according to any of claims 125 to 127, characterized by the valve means being also adapted in one position to block the second orifice while all other orifices are not blocked, and in another position to block all orifices except the second orifice.

129. The nozzle apparatus according to claim 124, characterized by the valve means being adapted in one position to block said second orifice and not block the third or both the first and third orifices, and in a second position to block the first orifice and not block either the second or the third orifice.

130. The nozzle apparatus according to claim 129, characterized by the valve means being further adapted in one position to block the second orifice while all other orifices are not blocked, and in another position block all orifices except the second orifice.

131. The nozzle apparatus according to any of claims 124 to 126, further characterized by means removed from the co-injection nozzle for moving polymeric melt, material to each of the nozzle passageways, and for reducing the flow of polymeric material through the third orifice while the valve means is in a position wherein neither the second nor the third orifice is blocked.

132. The nozzle apparatus according to claim 124, further characterized by the valve means comprising an elongated sleeve having an open end and a port in its wall opening to an elongated central passageway in the sleeve, the sleeve being mounted within the nozzle central channel in a close tolerance slip fit at least adjacent the first orifice and sufficient to prevent significant accumulation or passage of polymeric material therebetween, and an elongated pin mounted within the sleeve in a close tolerance slip fit within the central passageway of the sleeve sufficient to prevent significant accumulation or passage of melt material between the pin and the sleeve central passageway; the said sleeve being adapted to reciprocate axially within the nozzle central channel and operative to block and unblock said first and second orifices and to bring its port into and out of alignment with said third orifice and the pin being adapted to reciprocate axially within the sleeve to block and unblock the said port when the port is aligned with the third orifice.

133. The nozzle apparatus according to claim 132, characterized in that the third orifice is for passage of melt material (A) which is to form the core of a substantially concentric combined stream of melt materials (B,C,A) through the nozzle central channel, and the sleeve and pin are positionable to permit melt material (a) to flow through the third orifice while flow of melt material (C) through said second orifice is prevented.

134. The nozzle apparatus according to claim 133, further characterized in that the sleeve and pin are positionable to allow melt material (C) to flow through said second orifice while flow of melt material (A) through said third orifice is prevented.

135. The nozzle apparatus according to claim 125, characterized by first, second and third passageways each having an orifice defined by leading and trailing lips and communicating with said channel, said lips completely encircling the channel and each orifice having its center line substantially perpendicular to the axis of the central channel, the second orifice being axially intermediate the first and third orifices, and the nozzle , being further characterized by the valve means being axially and reciprocably mounted within said central channel and positionable (a) to block all of said orifices, (b) while said second orifice is blocked, to unblock the third orifice for flow of melt material (A) into the central channel as a solid stream, (c) to unblock the first orifice (482) to provide a flow of melt material (B) which completely surrounds the solid stream to provide a combined concentric flow stream of two materials to unblock the second orifice to allow melt material (C) to flow therethrough to enter between the said two materials and thereby provide a combined stream of three concentric layers (A, B, C), and (e) in turn to block the flow of the respective materials through the orifices in a sequence which is not the reverse of the flow-producing sequence (b) to (d).

136. The nozzle apparatus according to claim 135, characterized in that the valve means is adapted to clear the combined stream of three materials (A, B, C) , from the central channel at the end of the injection cycle at least up to the passageway orifice most proximate the gate.

137. The nozzle apparatus according to claim 135, characterized in that the first and second passageway orifices each have an axial width which is uniform about the central channel and is less than the cross-sectional width of the central channel, and the orifices are as proximate as possible to each other and to the gate so as to minimize the time taken by the combined stream of materials to reach the gate.

138. The nozzle apparatus according to claim 137, characterized by the distance from the trailing lip of the second orifice to the gate is from 100 to 600 mils (2.54 to 15.2 mm).

139. A nozzle apparatus according to claim 124, further characterized by at least the first and second of the orifices completely encircling and opening to a melt-combining area of the central channel, a leading lip of each orifice and the center line of each orifice lying substantially perpendicular to the axis of the central channel, the first passageway orifice being the orifice most proximate the gate and the third passageway orifice being most remote from the gate, each of the orifices having a cross-sectional area no greater than the cross-sectional area of the channel, and both the first and second orifices being as close as possible to each other and to the gate to minimize the time taken for the combined melt materials to flow to the gate, the nozzle apparatus being further characterized in that the valve means comprises (a) an elongated sleeve fitted in a close slip tolerance within said channel to reciprocate therein, the sleeve having an open end which, when the sleeve is in a forwardmost position, is aligned with and communicates with the gate, the sleeve having in its side wall a port adapted to communicate with the third passageway orifice, and (b) an elongated pin fitted in a close slip tolerance in said sleeve for reciprocable movement therein, the pin being moveable to a position which closes said port and being cooperative with said sleeve when they are in a forward position, to purge the combining area of said channel substantially completely, the tolerances between the channel, sleeve and pin being such that melt cannot accumulate between their confronting surfaces, and the valve means being moveable to respective positions whereat all orifices are blocked, all orifices are opened, only the first orifice is unblocked, only the third orifice is unblocked, and only the first and second are unblocked.

140. The nozzle apparatus according to claim 139, which includes drive means for driving said valve means between said positions.

141. The nozzle apparatus according to claim 139, characterized in that the valve means are adapted to unblock all the orifices within a period of 75 centiseconds, preferably within 20 centiseconds and more preferably within 15 centiseconds.

142. The nozzle apparatus according to claim 139, characterized in that the central channel has a uniform cross-sectional area at least from the first passageway orifice to the second passageway orifice.

143. The nozzle apparatus according to claim 139, characterized in that the first passageway has a leading wall which inclines towards the gate and towards the axis of the central channel and extends to the leading lip of the first orifice, the leading lip of the first orifice being closer to the axis of the central channel than the trailing lip of said orifice, and wherein the sleeve has a tapered mouth defining the sleeve open end which is adapted to abut against the said leading wall to limit movement of the sleeve toward the gate and block said first orifice.

144. A nozzle apparatus according to claim 139 characterized in that the valve means comprises an elongated sleeve fitted in a close slip tolerance within the central channel for reciprocation therein, the sleeve having a central passageway, a forward open end adapted to communicate with a portion of the central channel located between the first and second orifices, and there being a port in its wall so that the sleeve can block and unblock the third passageway orifice depending upon registry or misregistry of the port therewith, the sleeve being capable of moving to a position at which it blocks the first and second passageway orifices while port is in registry with the third passageway orifices while port is in registry with the third passageway orifice which is not blocked, and the valve means further includes means for blocking the port when in registry with the third passageway orifice, the port blocking means being adapted to be moved to a port-blocking position at the same time as the first and second orifice are not blocked, and to a port-unblocking position at the same time as the first and third orifices are not blocked and the port is in registry with the third orifice.

145. The nozzle apparatus according to claim 144 characterized in that said sleeve is also positionable such that the first and second orifices are unblocked, while the third orifice is blocked by the port being out of registry therewith and further positionable wherein all three orifices are at the same time blocked.

146. The nozzle apparatus according to claim 144 or 145, characterized in that the sleeve has a rear end portion and the means for blocking the port is a stationary member extending within a rear end portion of the sleeve central passageway partially to block the third orifice, said member being in a close tolerance slip fit within the sleeve central passageway and cooperative with the sleeve such that when the sleeve is withdrawn from a forward position, the sleeve port is aligned with the third orifice but is juxtaposed relative to and partially blocked .

147. An injection molding machine for injection molding a plurality of plastics articles which comprises, sources of polymer materials for the layers of the article, runner means extending downstream of the sources of polymer materials to each of a plurality of co-injection nozzle apparatuses each according to any of claims 124 to 126 and each mounted in the front of the runner means, said runner means including a plurality of polymer flow stream channels therein each for separately channelling a polymer melt material which is to form a layer of the article, from the source to each of the injection nozzles, and means for moving each stream of polymer material through the flow channels and into the respective nozzles, the valve means within the respective nozzles being operative to control the flow of the respective polymer melt materials from said passageways into the central channel of the injection nozzles for the injection of combined streams of said materials as simultaneous shots from the nozzles into juxtaposed injection cavities.

148. Apparatus for an injection molding machine, which is characterized by a co-injection nozzle means having a central channel with an open end, a gate at the open end, and two polymeric material melt flow stream passageways each having an orifice in communication with the central channel, the apparatus having a channel for each melt flow stream, each channel communicating with a respective passageway, common means in communication with each passageway for moving both polymeric material melt flow streams through their channels, passageways and orifices, and valve means mounted in the central channel and operative to block, partially block and unblock the orifices.

149. The apparatus according to claim 148 characterized in that the nozzle has an additional polymeric material melt flow stream passageway with an orifice in communication with the central channel, the additional passageway and orifice being located between the other passageways and orifices, and the valve means is operative to block the additional orifice while the other two orifices are not blocked thereby.

150. Apparatus according to claim 147 for injection molding a plurality of plastics articles each having at least five layers (A to E) laminated together, characterized by:

(i) a plurality of the co-injection nozzle means, and sources of polymeric material located upstream of the nozzle means, for each polymeric material which is to form one or more layers of the article, each of the co-injection nozzle means including at least five polymer material melt flow stream passageways, each communicating by a respective orifice with the central channel to pass a melt flow stream of polymeric material into the central channel, there being a first passageway with its orifice more proximate the gate than the other passageway orifices for passing a melt stream of material into the central channel for forming the outside surface layer of the article, a second passageway for passing a melt stream of material into the central channel for forming an internal layer of the article, a third passageway more remote from the gate than any of the other orifices for introducing into the central channel a melt stream of material (A) for forming the inside surface layer (A) of the article, a fourth passageway between the first and second passageways for passing a melt stream of material (E) into the central channel for forming an intermediate layer (E) between the outer surface layer (B) and the internal layer (C) of the article, and a fifth passageway between the internal passageway and the third passageway for passing a melt stream of material (D) into the central channel for forming an intermediate layer (D) batween the internal layer (C) and the inside surface layer (A) of the article, (ii) there are valve means operative in each nozzle means adjacent the orifices for controlling the flow of the respective polymeric materials through the orifices and into the central channel, each valve means being adapted in one positional mode to block the associated second orifice while the third orifice is not blocked, in another positional mode not to block the associated first orifice while partially blocking the third orifice, and in another positional mode not to block the first, second and fourth orifices while partially blocking the fifth orifice, the common moving means being associated with both the materials (B, A) to form the outside and inside surfaces for moving them into and through their respective first and third passageways and orifices, and, (iv) another moving means common to both materials (B, A) to form the intermediate layers for moving each of them into and through the respective fourth and fifth passageways and orifices.

151. The apparatus according to claim 150, characterized in that each of the valve means includes an axially- reciprocal, elongated sleeve seated in a close tolerance slip fit within the central channel of the associated nozzle means, the sleeve having a central passageway, a forward open end to communicate with the central channel and a port in its wall to communicate with the third passageway orifice, the sleeve being adapted to block and unblock the first, second, fourth and fifth orifices, and is operative in cooperation with another element of the valve means to block the third orifice, the said element cooperatively associated with the sleeve serving to block, partially block or unblock the sleeve port.

152. The apparatus according to claim 151, characterized in that the said element is a stationary member confined to a rear end portion of the sleeve's central passageway, the stationary member making a close tolerance slip fit within the sleeve central passageway.

153. The apparatus according to claim 150, characterized in that the valve means operative in each nozzle means includes an elongated axially reciprocable sleeve seated in a close tolerance slip fit within the central channel, the sleeve having a central passageway, a forward open end to communicate with the central channel and a port in its wall to communicate with the third passageway orifice, the sleeve being adapted to block and unblock the first, second, fourth and fifth orifices, and an elongated pin mounted axially reciprocably within the sleeve central passageway in a close tolerance slip fit, said sleeve and pin being cooperatively associated and adapted to be moved to different respective positions, so that in one position, said third passageway orifice is blocked while the first orifice is not blocked, in another position, the third orifice is partially blocked but the first orifice is not blocked, and in yet another position the fourth orifice is blocked but not the first, second and third orifices.

154. Apparatus according to any of claims 148 to 150, characterized by a plurality of substantially identical co-injection nozzle means having passageways for plural melt streams (B, A) which are to form corresponding respective layers of a plurality of injection molded articles, the apparatus having means common to and in communication with the passageways for each of at least two melt streams operative to move said at least two melt streams to each of the plural nozzle means, and each nozzle means having valve means to block, unblock, partially block flow through the passageways for said at least two melt streams, said valve means preferably being substantially identical and preferably operable substantially simultaneously.

155. A co-injection nozzle means for co-injecting a five layer plastic article, characterized by having an open end, a gate at the open end, a cylindrical central channel in communication with the gate, and five polymer flow stream passageways, each having an orifice in communication with the central channel and each adapted for passing a melt flow stream of polymeric material through the orifice into the central channel for forming a layer of the article, there being a first passageway having its orifice more proximate to the gate than any other orifice, for passing a melt stream of structural material into the central channel for forming the outside surface layer of the article, a second passageway for passing a melt stream of material (C) into the central channel for forming an internal layer of the article, a third passageway having its orifice more remote from the gate than any other orifice for passing a melt stream of structural material (A) into the central channel for forming the inside surface layer of the article, a fourth passageway between the first and second passageways for passing a melt stream of polymeric material (E) into the central channel for forming an intermediate layer between the outside surface layer and the internal layer of the article, and a fifth passageway between the second passageway and the third passageway for passing a melt stream of material (D) into the central channel for forming an intermediate layer between the internal layer and the inside surface layer of the article, and further characterized by valve means for the nozzle means and operative adjacent at least the second orifice and the third orifice and adapted at the same time to block the second orifice and not block the third orifice.

156. The co-injection nozzle means according to claim 155, characterized in that the valve means includes an elongated sleeve having an open end, a cylindrical side wall with a port therein, and an elongated axial central passageway in communication with the port and the open end, said sleeve being mounted within the nozzle central channel in a close tolerance slip fit sufficient to prevent significant accumulation or passage of polymeric material therebetween, and an elongated pin mounted within the sleeve central passageway in a close tolerance slip fit therewith sufficient to prevent significant accumulation or passage of melt material between the pin side wall outer surface and the sleeve central passageway wall, said sleeve being adapted to reciprocate axially within the nozzle central channel and operative to block and unblock the first and second passageway orifices and to bring its port into and out of alignment with the third passageway orifice, and said pin being adapted to reciprocate axially within said sleeve to block and unblock said port when the port is aligned with the third passageway.

157. The co-injection nozzle means according to claim 155, characterized in that the valve means is operative with respect to at least three of the five orifices, and is also adapted to block the second passageway orifice while it does not block the first and the third passageway orifices.

158. The co-injection nozzle means according to claim 155 characterized in that valve means is operative with respect to all five of the orifices and is adapted to block the second, fourth and fifth passageway orifices while said valve means does not block the third passageway orifice.

159. The co-injection nozzle means according to claim 158, characterized in that the valve means is further adapted at the same time to block the second orifice while said valve means does not block the first orifice, the third orifice, or both the first and third orifices.

160. The co-injection nozzle means according to any of claims 155 to 157, further characterized in that the first, second, fourth and fifth nozzle passageways are tapered towards their respective orifices such that each tapered passageway has a greater gap at an adjacent location remote from the orifice and a smaller gap at the orifice.

161. A method of injection molding characterized by forming a multi-layer combined stream of a plurality of polymer materials in injection nozzle means such that leading edges of the respective layers in the combined stream lie in planes in the nozzle which are substantially unbiased when viewed in vertical cross-section, the method involving the use of a co-injection nozzle having a central channel with a gate at one end, and at least first, second and third passageways, each having an orifice communicating with the central channel, there being one passageway for each layer to be formed in the combined stream, the first passageway orifice being more proximate the gate than the other passageway orifices for flow of the polymer material to form the outside layer of the combined stream, the third passageway orifice being remote from the gate for flow of the polymer material which will form the inside layer, and one or more second passageway orifices intermediate the first and third passageway orifices for flow of one or more polymer materials to form the internal layer or layers of the stream, the nozzle means further including valve means operative in the central channel for blocking the flow of polymer material from the orifices into the central channel, and for independently and selectively controlling the flow of polymer materials from the orifices, and the method involves the steps of operating the valve means for:
preventing flow from all of the orifices, preventing the flow of polymer material from the second passageway orifice or orifices, while allowing flow of material from the third orifice, the first orifice, or both the third and first orifices, and allowing flow of material through the second orifice or orifices while allowing material to flow through the third orifice or both the third and first orifices.

162. The method according to claim 161, further characterized by the step of utilizing the valve means for reducing the flow of the polymer material through the third orifice while allowing the flow of polymer material through the second orifice or orifices.

163. The method according to claim 161, further characterized by the step of preventing the flow of polymer material through the third orifice while allowing the flow of polymer material through the second orifice or orifices.

164. The method according to claim 163 further characterized by the step of terminating the flow of polymer Z material from the second orifice or orifices.

165. A method of making a multi-layer article by forming a substantially concentric combined stream of at least three polymeric materials and injecting said stream into a cavity to form the article, which has outside, at least one internal and inside layers formed from respective streams of the combined stream, namely an outer melt stream, at least one internal melt stream, and a core melt stream, the method being characterized by the use of a co-injection nozzle means having a gate at one end, a cylindrical central channel in communication with the gate, and at least three polymer passageways each communicating with the central channel by way of respective orifices, namely a first orifice located more proximate the gate than the other orifices, for routing the outer stream into the channel, a third orifice further removed from the gate than the other orifices for routing the core stream into the channel, and at least one second orifice positioned between the first and third orifices, for routing at least one internal stream into the channel, the nozzle further including valve means operative adjacent the orifices and adapted to prevent and to allow the flow of the internal stream(s) through the second orifice(s), and for independently controlling the flow or non-flow of the core stream through the third orifice, the method being further characterized by operating the valve means in the nozzle means (a) preventing flow of the internal stream(s) through the second orifice(s) while allowing flow through the first, the third, or both the first and third orifices, and then, (b) allowing flow through the second orifice(s) while allowing flow through the third orifice.

166. The method according to claim 165, further characterized by the step of utilizing the valve means for reducing flow through the third orifice while allowing flow through the second orifice.

167. The method according to claim 166, characterized in that after the reducing step there is included a step of utilizing the valve means for terminating the flow through the second orifice.

168. The method according to claim 167 characterized in that after terminating the flow from the second orifice, continued flow is allowed through the first orifice, the third orifice or both the first and third orifices.

169. The method according to any of claims 165 to 167 characterized in that before the flow preventing step (a), there is included the step of utilizing the valve means for preventing flow of polymeric material from all of the orifices.

170. The method according to claim 168 wherein the nozzle central channel includes a combining area in which the combined stream is formed and wherein after the step of preventing flow of polymeric material from all orifices, the method is further characterized by a step of utilizing the valve means for substantially completely clearing the combining area of polymer material prior to forming the next combined stream of material in the central channel.

171. The method according to claim 170 further characterized by use of the valve means to prevent back-up of polymer material from one orifice into another orifice.

172. The method according to claim 165, further characterized by a step of substantially knitting in the nozzle means the internal melt stream material with itself through the core material, and by moving the valve means forward through the central channel toward the gate to assist in knitting the internal layer material.

173. The method according to claim 172, characterized by the step of moving the valve means forward to assist in effecting in the nozzle means the encapsulation in core material of the knitted internal material.

174. The method according to claim 172 or 173, characterized by the moving of the valve means forward to move the combined stream through the gate into an injection cavity without disruption of the knitted internal material.

175. The method according to any of claims 165 to 167, characterized in that after flow-allowing step (b) there is included the steps of utilizing the valve means for allowing the flow of materials from all the orifices and then for preventing the flow from all the orifices, and the time elapsed between these allowing and preventing steps is from 60 to 700 centiseconds, preferably from 60 to 250 centiseconds.

176. The method according to claim 165, characterized by operating the valve means in the nozzle means for the steps of (i) preventing flow of polymer material from all of the orifices, (ii) preventing flow of polymer material through the second orifice while allowing of structural material through the first, the third or both the first and third orifices, then, (iii) allowing flow of polymer material through the second orifice while allowing material to flow through the third orifice, (iv) restricting the flow of polymer material through the third orifice while allowing the flow of material through the second orifice, (v) restricting the flow of polymer material through the second orifice while allowing flow of polymer material through the first or third orifices or both the first and third orifices to knit the intermediate layer material with itself through the core material and substantially encapsulate the intermediate layer in the combined stream and in the shot.

177. The method according to claim 176, characterized by including after step (v), the step of utilizing the valve means for clearing all or most of the polymer material from the central channel.

178. The method according to claim 177, further characterized by including the step of utilizing the valve means during said clearing step for preventing back flow of polymer material from the central channel into an orifice, or from one of the orifices into another orifice.

179. The method according to claim 176, further characterized by including the step of moving the valve means through the central channel towards the gate during step (v) to assist in knitting the internal layer material.

180. The method according to claim 179, characterized by moving the valve means to move the combined stream through the gate into an injection cavity without disruption of the knit.

181. The method according to any of claims 176 to 178, characterized in that during step (iii) material is allowed to flow through the first orifice, and steps (ii) and (iii) are performed within 250 centiseconds, preferably within 100 centiseconds.

182. The method according to claim 165, characterized by operating the valve means in the nozzle for forming the combined stream by the steps of:
(i) preventing flow of polymer material through the second orifice(s) while allowing flow of polymer material through the first orifice, the third orifice or both the first and third orifices, (ii) then allowing flow of polymer material through the second orifice(s) while allowing polymer material to flow through the third orifice, (iii) reducing the flow of polymer material through the third orifice while allowing polymer material to flow through the second orifice(s), (iv) terminating the flow of polymer material through the second orifice(s), and (v) allowing flow of polymer material only through the first orifice while preventing flow of polymer material from the second and third orifices to substantially encapsulate the intermediate polymer material(s) in the combined stream.

183. The method according to 182, characterized in that after step (v) there is included a step of substantially completely purging the polymer materials from the nozzle central channel prior to the next injection cycle.

184. A method according to any of claims 165 to 167, further characterized by a step of forming the combined stream wherein the leading edge of the one or more internal layer(s) is substantially unbiased relative to a vertical plane drawn perpendicularly and transaxially through the shot.

185. The method according to any of claims 161 to 163, further characterized by practicing the method to form a plurality of combined streams in a plurality of the co-injection nozzle means and injecting the said streams with a plurality of associated injection cavities, the nozzle means preferably including valve means which are substantially identical and are preferably operable substantially simultaneously.

186. A method of injection molding to produce an article, such as a parison, having a wall composed of at least three layers, wherein melt material streams to form said layers are injected into a mold cavity through a co-injection nozzle having a central channel, at least three melt stream passageways each with an orifice which communicates with the central channel, the method being characterized by the use of a nozzle containing valve means in the central channel, and further characterized by the steps of moving the valve means to a first position to prevent flow of the melt material streams into the nozzle central channel, moving the valve means to a second position to permit the flow of a first material stream into the nozzle central channel, moving the valve means to a third position to permit continued flow of said first material stream and to permit flow of a second material stream into the nozzle central channel, and moving the valve means to a fourth position to permit continued flow of said first and second streams, and to permit flow of a third material stream into the nozzle central channel between the first and second streams.

187. A method according to claim 186, characterized in that the second material stream is admitted as an annular flow around the first stream and the third material stream is admitted as an annular flow between the first and second material streams.

188. The method according to claim 186 or claim 187, further characterized by imparting pressure to at least the third material stream prior to or concurrently with moving the valve means to the fourth position.

189. The method according to claim 186 or claim 187 further characterized by imparting pressure to the third stream in a passageway and to at least one of the first and second streams in the central channel, and, prior to or concurrent with moving the valve means to the fourth position, adjusting the pressure of one or more of the said streams so that the pressure of the third stream is then greater than the pressure of either one of the first and second streams in the central channel.

190. The method according to claim 186, further characterized by imparting pressure to the third stream and to at least one of the first and second streams, and, prior to or concurrent with moving the valve means to the fourth position, adjusting the pressure of one or more of the said streams so that the pressure of the third stream is greater than the pressure of the first and second streams.

191. The method according to claim 190 further characterized by imparting pressure to the said first, second and third streams, and, prior to or concurrently with moving the valve means to the fourth position, increasing the pressure of the third stream and reducing the pressure of at least one of the first and second streams.

192. Apparatus for selectively controlling the flow of at least three melt material streams for injection molding multi-layer plastics articles from the melt materials, characterized by a nozzle having a central channel open at one end, a flow passageway in the nozzle for each of a plurality of material streams, at least two of the nozzle passageways terminating at a respective exit orifice, each of which communicates with the nozzle central channel preferably adjacent the open end, and by sleeve valve means having an axial material flow passageway communicating with the nozzle central channel and adapted to communicate with a flow passageway for conveying a material stream to the nozzle central channel, the sleeve means being carried in the central channel and being moveable to selected positions to block and unblock one or more of said orifices and to bring the said axial passageway into and out of communication with the said flow passageway.

193. The apparatus according to claim 192, characterized by the nozzle having a flow passageway for each of at least two of said material streams, and the sleeve means being adapted to communicate with a flow passage- way external of the nozzle, and moveable to bring said internal axial passageway into and out of communication with one or more of said nozzle passageways.

194. The apparatus according to claim 192 characterized by the sleeve having said axial passageway formed in or by the interior thereof.

195. The apparatus according to claim 192, characterized in that communication from the internal axial passageway of the sleeve means to the said flow passageway is through a port or aperture in the wall of the sleeve means.

196. The apparatus according to claim 195, characterized in that the sleeve means is moveable axially, rotationally or both in the central channel of the nozzle to selected positions, thereby to block and unblock one or more of the orifices and to bring said port or aperture into and out of alignment with the said flow passageway.

197. The apparatus according to any of claims 192 to 194, characterized by the sleeve means being moveable to selected positions to block and unblock at least two of the said orifices.

198. The apparatus according to any of claims 192 to 194, characterized by the exit orifices completely surrounding the nozzle central channel.

199. The apparatus according to any of claims 192 to 194, characterized in that the sleeve means fits closely within the nozzle central channel whereby there is no substantial cavity for polymer accumulation between the sleeve means and the central channel.

200. The apparatus according to any of claims 192 to 194, characterized by the plane of at least one of the said orifices being perpendicular to the axis of the central channel.

201. The apparatus according to any of claims 192 to 194, characterized by a plurality of further flow passageways for a plurality of further material streams, and by the sleeve means having a plurality of axial flow passageways therefor.

202. The apparatus according to claim 192, further characterized by means to actuate and move the sleeve means between first, second, third, fourth, fifth and sixth modes, wherein in said first mode the sleeve means blocks all of the said orifices and said axial passageway is out of communication with the said flow passageway, in said second mode the sleeve means blocks all of the orifices and said axial passageway is in communication with the said flow passageway, in said third mode the sleeve means does not block the orifice most proximate to the open end of the nozzle central channel and said axial passageway is in communication with the said flow passageway, in said fourth mode the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is in communication with the said flow passageway, in said fifth mode the sleeve means does not block at least two orifices, one of which is the orifice most proximate to the open end of said nozzle central channel, and said axial passageway is out of communication with the said flow passageway, and in said sixth mode the sleeve means does not block the orifice most proximate to the open end of said nozzle central channel and said axial passageway is out of communication with the said flow passageway.

203. The apparatus according to claim 202, characterized in that the actuating means is operative to move the sleeve means sequentially from said first position to each of said second to sixth positions and then to said first position.

204. The apparatus according claim 192, adapted to control five material streams.

205. The apparatus according to claim 204, characterized in that the nozzle includes four exit orifices communicating with the nozzle central channel and the sleeve means has one internal flow passageway and one aperture in the wall thereof.

206. The apparatus according to claim 204, characterized in that the nozzle includes three exit orifices communicating with the nozzle central channel and the sleeve means includes two internal material flow passageways and has two apertures in the wall thereof each communicating with said nozzle passageway.

207. Apparatus according to claim 203, characterized by pin means movable, by actuating means therefor, in the axial passageway of the sleeve means to selected positions to block or permit communication between said internal axial passageway and the or a flow passageway to be communicable therewith.

208. The apparatus according to claim 207, characterized by the actuating means for both the sleeve means and the pin means are operative to move them sequentially from said first mode to each of said second to sixth modes and then to said first mode.

209. The apparatus according to claim 207 or claim 208, characterized by one end of the pin means being proximate to the open end of the nozzle central channel when the sleeve means and the pin means are in said first mode.

210. The apparatus according to any of claims 192 to 194, further characterized by material flow directing means associated with the nozzle for balancing the flow of at least one material stream around the nozzle passageway and exit orifice through which the stream flows.

211. The apparatus according to any of claims 192 to 194, further characterized by means for pressurizing at least one material stream.

212. The apparatus according to claim 192, further characterized by material flow directing means in at least one of said nozzle passageways for balancing the flow of the associated material stream around said passageway and the exit orifice through which it flows, and means for pressurizing said stream to produce a pressurized reservoir of material in said nozzle passageway between said flow directing means and said orifice, whereby, when the sleeve means unblocks said orifice, the start of flow of said material through said orifice is substantially uniform around the orifice.

213. The apparatus according to claim 212, characterized by the said at least one nozzle passageway being tapered toward its associated orifice from a wide gap remote from the orifice to a narrow gap at the orifice.

214. The apparatus according to any of claims 192 to 194, characterized in that the nozzle has four, five or more passageways with orifices communicating with the central channel at locations close to the open end.

215. Apparatus according to claim 192 for co-injecting at least three melt material streams through the nozzle into a cavity to form a thin wall multi-layer plastic article having at least one thin internal layer having a terminal end, characterized in that the nozzle has material flow directing means for balancing the flow of the material stream (C) which forms the said internal layer around the nozzle passageway and exit orifice through which that stream flows, the flow directing means being operative to locate the terminal end of the internal layer substantially uniformly in the injected article at the conclusion of polymer movement in said injection cavity.

216. The apparatus according to claim 215, further characterized by means for pressurizing at least the internal layer material stream.

217. The apparatus according to claim 216, characterized in that the said material flow directing means is located in the nozzle passageway for the material to form said internal layer, the said passageway providing for a pressurized reservoir of the material therein located between said flow directing means and the exit orifice of the said passageway to said central channel, whereby, when the said orifice is unblocked, the start of flow of the pressurized internal layer material into said central channel is substantially uniform around the channel.

218. The apparatus according to claim 217, characterized in that the said nozzle passageway for the material to form the internal layer is tapered and has a wider gap remote from its exit orifice and has a narrower gap at the orifice.

219. Apparatus according to claim 192, for co-injecting at least three melt material streams through the nozzle into a cavity to form thin wall multi-layer plastic article having an outer layer having a terminal end, characterized in that the nozzle has material flow directing means for balancing the flow of the material stream (B) which forms said outer layer around the nozzle passageway and exit orifice through which that stream flows, the flow directing means being operative to locate the terminal end of said outer layer substantially uniformly in the injected article at the conclusion of polymer movement in said injection cavity.

220. The apparatus according to claim 219, further characterized by means for pressurizing the outer layer material stream.

221. The apparatus according to claim 220, characterized in that the said material flow directing means is located in the nozzle passageway for the material to form said outer layer, the said passageway providing for a pressurized reservoir of the material therein located between said flow directing means and the exit orifice of the said passageway to said central channel, whereby, when the said orifice is unblocked, the start of flow of the pressurized outer layer material into said central channel is substantially uniform around the channel.

222. The apparatus according to claim 221, characterized in that the said nozzle passageway for the material to form the outer layer is tapered and has a wider gap remote from its associated orifice and has a narrower gap at the orifice.

223. Apparatus according to any of claims 215 to 217, characterized in that the material streams to form both the internal and the outer layers of the article are subjected to flow directing means operative to balance the flows of the material streams (B, C) which form said outer and internal layers and to locate around the nozzle passageways and exit orifices through which said streams flow, to locate the terminal ends of each of these layers substantially uniformly in the injected article at the conclusion of polymer movement in said injection cavity.

224. Apparatus according to any of claims 192 to 194, characterized by means for selectively controlling the flow of at least three melt material streams through the nozzle of a machine for co-injecting the materials into a cavity to form thin wall multi-layer plastic articles having an outer layer and at least one thin internal layer, wherein the nozzle has a central channel open at one end, comprising a flow passageway in the nozzle for each material stream, at least two of the nozzle passageways terminating at an exit orifice, each of said orifices communicating with the nozzle central channel at locations close to the open end, sleeve means having at least one internal axial passageway communicating with the nozzle central channel and adapted to communicate with one of the flow passageways in the nozzle, said sleeve being carried in said nozzle central channel and being moveable to selected positions to block and unblock one or more of said orifices, pin means moveable in the axial passageway of the sleeve means to selected positions to block and establish communication between said internal axial passageway and said nozzle passageway, and material flow directing means associated with the nozzle for balancing the flows of the material streams (B, C) which form said outer layer and the internal layer around the respective nozzle passageways and exit orifices through which said streams flow, whereby the locations of the terminal ends of said outer layer and said internal layer are substantially uniform in the injected article at the conclusion of polymer movements in said injection cavity.