US2799435A - Molded nylon container - Google Patents

Description

July 16, 1957 R.H. ABPLANALP MOLDED NYLON CONTAINER Filed June 9, 1954 s sheets-sheet 2 INVENTOR. Poes/QT# 45m num/2 R. H. ABPLANALP MOLDED NYLON CONTAINER July 16, 1957 :s sheets-sheen s Filed June- 9,- 1954 I \\\\S\ QJ m .muhlly Y lNvENToR Poseer H. Hamm/HLP BY- f A'rroRNEY Uited States Patent MoLDED NYLON CONTAINER Robert Henry Abplanalp, Bronxville, N. Y., assigner, by direct and mesne assignments, of'one-lialf to John J. Baessler, Yonkers, N. Y.

Application .lune 9, 1954, Serial No. 4135,4i8Y

Claims. (Cl. 222-394) This application is a continuation-in-part of my application for patent, Serial No. 417,554, tiled March 22, 1954.

This invention relates to nylon containers.- andmore particularly to containers primarily adapted for use in connection with the dispensing of aerosol products.

Many such aerosol products are of suchV character that they will detrimentally act upon the ordinaryrmetal containers and therefore it has beenv generally considered necessary to package them in glass which, because of its readily breakable character constitutesa threat to the user particularly if such glass container is struck against extraneous objects or dropped. There has long .beena real need for an appropriate container for such materials, as well as aerosol materials generally,y which wouldv be'rela'- tively strong, not readily broken, neutraly to attack by aerosols generally and relatively economical to manufacture. Nylon is a material wellladapted to fulfill these requirements, but because of price factors, its use in this connection has heretofore been considered uneconomical in a molded container.

As a result of protracted experimentation and research, I have conceived a method of making a nylon container which will effect sufficient saving in material to permit it to be competitive with the glass and metal containers presently employed. This result is accomplished by molding the container with such thin walls that the amount of nylon required to make a container of a predetermined size is' minimized and brought within the' price range necessary to permit of its commercial'use.

Nylon is noted for its extremetoughness and strength, so that a container With relatively thin Walls is.well able to withstand the pressures usually employed in aerosol packaging. However, nylon has` the property of setting or solidifying so rapidly that anyV atternpt` to pressure mold it in conventional dies requires a relatively large spacing` of the core from the Wallr of the mold cavity in order to permit of a suiciently rapid filling ofthe cavity to insure a completely formed' homogeneous cast. If an attempt is made tocast a thin walled receptacle according to conventional molding practice, the nylon admitted to the cavity in liquid form tends to set up before the cavity is completely filled and consequently end products are produced which are either incomplete or imperfect.

The present invention overcomes, this difliculty and permits of the molding of very thin walled nylon containers, absolutely homogeneous in character.. without aws in their structure and through the use of comparatively small quantities of nylon.

Heretofore it has been the practice in molding generally to admit the casting material into the mold cavity at one end thereof with the spacing between the cavity and its core suiciently great to permit the molding materiall to lill the cavity before it can' set or solidify. In contradistinction to this practice, the present invention. comprehends' the gating of the cavity at dierent points in its circumference, and having those gates intro'duce' the ICC material into the cavity into supplemental runners formed either in the core or in the cavity wall. These runners are arranged in spaced apart relation about the circumference of the cavity, so that the casting material, as it enters the cavity, flows immediately and in an unimpeded manner throughout the length of the supplemental runners and is fed from these runners circumferentially of the cavity with such rapidity that the feeds from adjacent supplemental runners intermingle intermediatesaid runs ners to form a homogeneous wall of castingmateral before the material has a chance to lose its liquid condition and set. By this arrangement I have found thatv it is possible to make those circumferential portions of. the cast, intermediate the supplemental runners, veryr thin and at the same time obtain an absolutely homogeneous cast.

The supplemental runners preferablyl extend from the gate for substantially the full lengthof the cast so that the casting material may be thus fed in a rapid and efcient manner to all parts of the cavity.

The container is preferably cast'with an open bottom, the closure for which may be separately cast and heat sealed to the container in the novel and eiicient manner hereinafter more fully explained.

One object'of the present invention is to make a nylon container of the maximum strength with a minimum amount of nylon material, through novel proportioningv of the cross sectional area of the beads with respect to the cross sectional wall area which lies. between the beads.

Another object of the invention is to provide a nylon container' structure wherein the wall thickness at one side of the container is less than the wall thickness at the other side, so that, if the'outlet nozzle of the container is positioned at the side which embodies the thin walls, the rupture of suchcontainer, due to the building up of excess aerosol pressures therein, will be ina direction away from theuser, who invariably holds anaerosol container with the nozzlepointed away from him.

Features of the invention7 other than those advertedv to, will be apparent from the hereinafter detailed description and appended claims, when read'in conjunction' with the accompanying drawings.`

The accompanying drawings illustratev the invention in its preferred practicalforms, but the `constructionsshown therein arek to be understood as illustrative, only, and not as dening the limits off the invention.

Fig; l is a central section throughra pressure castingdiev for,y carrying out the` method and producing theY articlel of the p'resent'invention'. This section is taken inV the plane of the line 1 1. oflFig. 3. In this figure the cast is shown inthe die.

Fig. 2 is afragrnental section on the line 2,-2' o fl Fig; l with the castomitted'.

Fig.l 3v is a fragmental bottom view of thel upper die section shownrinvEig. 1, withv the cores ofthe lower sec,-V tion in .sectionV and theA castin place.V

Fig; 4" shows the`v cast body. of' one, container. madefin.

1:.`ig..6y is a plan rviewof, the heat conductive ring shown inFig. 4. Y

Fig; 7 showsr` the containerv incentraly section with an aerosol dispensing val've unit ,andv dip tube incorporated.

therein.

Fig, 8 is an/elevation 'of the structure shown in Fig, 71 with a push button mounted.' on the valve stem of the. dispensing valve unit.A

Fig. 9 is a central section of` a molded` body of one form of container embodying the present invention, said section being taken in the plane of the line 9 9 of Fig. l0.

. Fig.y is a transverse section on the line 10--10 of Figs. 9 and 12.

Fig. 1l is a section similarto Fig. l0, but showing six internal beads instead of the four shown in Fig. l0.

Figs.' l2 and 13 are views similar to Fig. 9, but illustrating different dispositions of the beads.

Fig. 14 is a section on the line 14-14 of Fig. 13.

Fig.; is a transverse section on the line 15-15 of Fig. 16 and is a view similar to Figs. 9 and l0, but showing a modified form of construction.

, Fig. 16 is a transverse section on the line 16-16 of Fig. 15.

In the accompanying drawings, 1 and 2 designate the cooperating sections of a pressure molding die. In thc drawings I have not included all the details of this die construction,` but have simply shown the features appropriate to the present invention.

- The section 1 of the die has a sprue passage 3 which leads to transverse runners 4. In practice, it is convenient and economical to cast four articles at a time and there are thus four of such runners arranged at 90 to one another, although a different number of articles and runners may be employed if so desired.

Contrary to usual practice, the runners 4 do not feed the cavities directly, but rather these runners terminate in runner manifolds 5 of circular form and each of these runner manifolds have radial extensions 6 which lead to the cavities 7 of the die section 1. The die section 2 is provided with cores 8 adapted, whenthe die sections are in assembled relation, to project into the cavities 7, as shown in Fig. l. These cores have an overall shape complementary to the mold cavities and throughout the major portion of their extent are spaced equi-distant from the wall of the cavity. However, each core is provided with a plurality of longitudinally extending supplemental runners 9 which are respectively juxtaposed to the several extensions 6 and they extend for substantially the full depth of that portion of the cavity which is to form the body of the container. The container to be cast in the die of Figs. 1-3 is provided at its lower edge with an external flange 12, as shown in Figs. 4, 5 and 7, and the extensions 6 are gated to the tiange portion of the cavity at gates 10 of reduced section, so that, after the cast has been made, the container may be readily broken away from the extraneous solidified scrap.

The major portion of the space between the core and each cavity is relatively small as shown at the extreme right in Fig. 1. These thin portions extend from the somewhat thickened portion of the cavity which is to form the bottom flange, to the top of the cavity and are located between the several supplemental runners 9.

The runners 4, manifolds 5 and the extensions 6 are formed collectively within the sections 1 and 2 and at the plane of separation of said sections. These runners, manifolds and extensions are of ample size to feed the casting material rapidly from the sprue passage 3 to the supplemental runners, and these supplemental runners are of su'cient cross section to rapidly feed the casting material circumferentially of the core until the liquid material from adjacent supplemental runners meets and commingles to form the thin wall section.

The casting material is fed in heated condition to the sprue passage 3 by conventional pressure molding apparatus, instantaneously fills the several cavities, and thereafter quickly sets, so that the sections may be separated from kone another to withdraw the cast. Appropriate Y conventional Aejector means may be associated with one or both of the mold sections to facilitate the removal of the cast, but a showing of this mechanism is considered unnecessary as it is common in the art of pressure molding.

The .cavitiesV may be vented in any suitable manner, as through vent passages 11 indicated in Fig. 1.

The four container bodies, together with the material accumulated in the sprue passage, runners, manifolds and extensions come from the die in one piece, but because of the constricted gating 10, the cast containers are readily broken away from the remaining scrap which may be reheated and use for subsequent casting operations.

Each cast container body, as it comes from the mold section 1, is shown in section, with the scrap removed, in Figs. 4 and 9. It will be here apparent that the major portion of the wall of the container is relatively thin except for the bottom flange 12. The upper portion of neck of the container may be made of the same thickness as the side walls, but, if desired, it may be slightly thicker. However, in forming the cast, a relatively small internal circumferential ridge 13 is preferably formed circumferentially of the neck, as shown in this figure, and the neck is provided with a closed end having a central perforation 14.

Because of the presence of the supplementary runners 9 of the core, the interior of the cast will have correspondingly shaped beads 15 formed integral with the cast. In the drawings, these beads are shown somewhat larger than they need be in the interest of clearness, but their size will of course depend upon the section of the supplemental runners necessary to properly feed the casting material as hereinbefore described. In the preferred form of this invention, the beads 15 are formed on the inside of the container and they result from the formation of the supplemental runners in the core. However, these beads may be formed on the exterior of the container by forming the supplemental runners in the face of the cavity Wall. In any event, they strengthen and reinforce the container without materially adding to its weight or to the quantity of nylon employed in its formation. If exteriorly positioned, they impart ornamentation to the exterior of the article and are for this reason not objectionable.

The ridge 13 in the neck is to facilitate the association of an aerosol valve dispensing unit with the container. I may conveniently employ in this connection a unit of the character disclosed in my Patent No. 2,631,814, granted March 17, 1953. This unit is indicated in Fig. 7 of the drawings by the reference character 16. It is provided with a circumferential channel to receive the ridge 13. This channel may be brought into cooperation with the ridge 13 by introducing the valve unit through the bottom of the container into the neck thereof and, by thereupon imparting pressure to the bottom of the unit, said unit may be sprung into engagement with the ridge, for the nylon cast has suicient elasticity and elastic re covery to permit of this operation and assure a tight fitting relation between the ridge and the channel of the valve unit. The usual dip tube 17 is attached to the valve unit either before or after the mounting of the unit within the container.

The open lower end of the container may be closed by a bottom closure 18, shown in section in Fig. 4. This may be cast from nylon according to conventional pressure casting practice or through the use of a manifold as previously described. However, it is preferably made somewhat thicker than the thin walls of the body of the container for the same reason that the flange 12 is made of greater thickness, namely, to permit these parts to be fused together without dissipating the structure. This fusing is accomplished by a process of heat sealing. It is facilitated by the employment of a metal ring 19, perforated as shown in Fig. 6. This ring is interposed between the flange 12 and the bottom closure 13 and, while the parts are thus held assembled under pressure, the ring 19 is electrically inductively heated. This causes the surface strata of the parts which contact the ring to be fused whereby some of such material will ow through the perforations in the ring 19 and commingle to form a homogeneous bond, while those portions of the ange andclosure which Contact with the unperforated portion of the ring will form a rm bond with the latter.y In

thisway', the closure is heat sealed to the containerl in a pressure tight impervious joint. There is thereafter attached to theA valve stem of the unit 16, the usual push button 21.

It will of course be understood that the container may b e filled with the material to be dispensed therefrom in any appropriate manner either before or after applying the bottom closure. The invention is not limited in this respect.

One of the ever present dangers in the use of aerosol containers is the danger of bursting under pressures contained therein. This is particularly true when glass containers are employed for, in the event of such bursting, the glass shatters and splinters and fragments thereof are impelled with sufficiently great force to do harm to the` user or one who may be close at hand. Nylon also has the property of shattering and splintering under like conditions and, while this material is so light that no great' harm can be done thereby, I have found it possible to overcome the tendency of the nylon container to shatter in the event of breakage, by providing one or more lines of 'weakness 22 longitudinally of the body of the container. These lines are, in practice, relatively fine score lines. They do not seriously weaken the container for nor-mal use, but in the event that the pressures within the cointainer become too great, as by overheating, the container will simply split along one or more of these lines of weakness with a clean cleavage and without shattering or the throwing of fragments of splinters. The formation of these score lines may be accomplished by placing minute .ribs along either the cavity or the core of the die and in this manner they may be formed on the cast either externally or interiorly of the container wall.

Containers of widely different sizes may be made according to the present invention and the minimum wall thickness will ordinarily depend upon the size of the container, but in every case a relatively thin wall is permissible and adequate with consequent great saving of nylon without sacrificing the necessary strength.

The present invention, as hereinbefore stated, is primarily directed to the making of nylon containers. I wish it understood, however, that the methodand structure which I- have described may be utilized in the manufacture of containers from other plastics and the invention is to be understood as not necessarily limited to its 'primary nylon aspect.

The foregoing detailed description dealing with Figs. 1 8 inclusive Vsets forth the general principles of this invention with respect to the method of pressure molding a container according to the invention.

The container body shown in Figs. 9 and l0 would appear to the casual observer to be the same container body vas shown in Figs. 4 and 5. There are, however, certain inherent features of `outstanding importance in Athe structure of Figs. 9 and l0. For example, in the structure of Figs. 9 and 10, there is a definite relationship 4between the cross sectional areas of the beads 28 and the cross sectional areas of those portions of the kcontainer wall between adjacent beads.

As a result of protracted experimentation, research and tests, I have discovered that there is an optimum .relation or vratio between these areas which will permit a nylon container to be made with walls of minimum thickness but of maximum strength with a minimum quantity or weight of nylon to produce a container body of a desired size. I have further found that the ratio between these areas remains substantially constant irrespective of the size of the container, i. e., irrespective as to whether ithejcontainer is, e. g., l ounce or 1 quart capacity. My tests have shown that the area of the cross sectional wall thickness will range Vbetween 11/2 and 31/2 times the cross sectional 'area of the beads which are requisite to the making of perfectly homogeneous casts from nylon material.l 'More specically, by reference'to Fig. '10, 'where the wall thickness as between the several beads 28 i's constant or uniform throughout the circumference of the container, the combined areas of the four sections indicated at w should be ll/z to 31/2 times the aggregate cross sectional areas b of the four beads. A good average is from 2 to 3 times. In order that these areas may be graphically defined in Fig. l0, the cross sectional area b of each of the beads is shown in solid black, while the cross sectional area w of each of the arcuate wall sections is shown as cross hatched.

No attempt has been made to show in the drawings accurate proportions between the wall or bead dimensions or areas, the written description being depended upon to supply this information.

The beads must have suflicient cross sectional area, so that during the feed of the nylon into the die, the material fed circumferentially from the runnerwhich forms each bead, will commingle with the material fed from the runners which form the next adjacent beads, before such material can set or solidify to such degree as to preclude a continuous homogeneous wall structure. The area of the beads will vary according to the circumferential distance between them, so that, in the structure ofy Fig. l0 which shows four beads, the cross sectional area of the beads will be greater than in such a structure as, for example, Fig. 1l, where six beads with closer spacing are provided. In Fig. 1l, the material has to flow from the ydie runners a less distance than in the case of Fig. 10 and consequently the runners may be made smaller for less material must be fed through each of them. Nevertheless the optimum ratio to which I have referred will prevail in the structure of Fig. ll as it does in Fig. 10. I wish it understood in this connection that Imay use any number of beads desired without departing from this invention, although ordinarily container bodies of larger capacity will generally require a greater number of beads so that the size of the individual beads, as well as the quantity of nylon used, may be kept at a minimum.

In Fig. 9, the beads are shown as extending for substantially the full height of the body. In the manufacture of such a container body, the beads may be formed by gating the die cavity at either one or both ends as may be desired. However, it is not necessary to have the beads extend for the full height of the body. They may be arranged in groups at different elevations, as shown for example in Figs. 12-14 inclusive.

In Fig. l2 there is an upper set of beads 28a and a lower set of beads '28b which will ordinarily be die cast by gating `each set independently of the other. In other Words, the set 28h may be gated as described in my copending application, while the upper set of beads 28a may be gated at any ydesired portion of their length preferably at `their upper ends.

In Fig. 12, the beads .of the upper and lower sets 28a and 28b are. in vertical alinement with one another, although, if desired, they may be staggered as shown in Figs. 13 and 14. In view of these facts, I wish it understood that either one or more sets of beads may be used and, as described in .my copending application, they may be positioned either on the interior or exterior wall of the vcontainer body. y'In other words, the runners which form these beads'may be either in the core or in the wall ot' the die cavity. If the container is substantially cylindrical or otherwise of substantially the same size 'throughout its height, the beads vmay be of uniform cross ysection throughout 'their length, although they may be tapered if desired and it is preferable that in containers of some shapes the beads at the smaller cross sectional area of the body be made smaller than those at the larger cross section of the body. This may also be true in cases where it is desirable to make the wall of the body of different thicknesses throughout its depth, as, for,` example, where abody is made with a larger lower portion and a considerably smaller upper portion.

In the yinventiona's shown in Figs. 9-14, inclusive, the wall thickness between the'beads is substantially uniform throughout the circumference of the container, so that if the container bursts due to a building up of excess pressure therein, the break may occur at any place in the circumference or length of the container. In Fig. 8, provision is made for weakening one part of the container by forming at a selected location a score line or the like. Similar provision may be made in the container of Figs. 9-14. However, my experience and tests have resulted in the conception of a much better way of guarding the user against damage from burstingif such should occur. Figs.15 and 16 are illustrative of this improvement.

The production of a container body according to Figs. l and 16 may be conveniently accomplished by so positiOning the core in the mold cavity of the die that it is eccentric thereto, i. e., olf center, so that in the resulting molded article, the inner surface i of the wall of the container will be eccentric to the outer surface o of said wall, as clearly shown in Fig. 16. l This arrangement will provide a thinner wall at one side of the container than at the opposite side thereof. Said thinner wall section will constitute an area of weakness t as compared to the remaining portion of the body wall, so that, if the pressure becomes too great within the container, it will be released through its zone of weakness which constitutes, in effect, a safety'valve.

The best results are obtainable in an aerosol container laccording to Figs. and 16, if the valve unit 29 for this container is mounted so that the spout or nozzel 30 of the push button 31 will point in the direction of this zone of weakness, so that if `the material in the container breaks loose through the wall thereof, it will do so in the direction in which the nozzle points.

It has been found that when excess pressures occur in such an aerosol container, they build up gradually rather than instantaneously. As the pressure increases, the natural elasticity of the nylon wall causes it to bulge in the zone of weakness. This bulging is at rst almost imperceptible, but, as the pressure increases, such bulging can be readily felt by a person whose hand is grasping the container. As the bulging increases, experience has shown that a blister is propagated in the weaker zone and this blister becomes larger and swells until it finally bursts to release the internal pressure. Consequently ifa person is holding the container in his hand at the time that these phenomena take place, he can immediately feel that something is wrong and will instinctively drop the container. However, if he does not do so before the material is released, the forming and subsequent bursting of the blister will push his lingers aside and out of the direct ow of such material and thus safeguard his hand against injury. An important feature of this mode of operation is that the wall stretches to breaking point before bursting and tearsv at the apex of the blister so that practically no particles of thev container are thrown or scattered.

This safety measure is much superior to the score lines 22 shown in Fig. 8.

The container shown in Figs. 15 and 16 is shown as provided with appropriate beads as in the previous figures and it may be molded in the same manner but with the core off center of the cavity, as stated, to give the ec centneity between the inner and outer surfaces of the body shown in Fig. 16. Even in this construction it is found that the general proportion between the aggregate cross sectional area of the several beads and the aggregate cross sectional area of the intermediate wall sections i it understood that the beads may be omitted without departing from this aspect of the invention.

The containers of Figs. 9-16 are provided at their bottoms with peripheral llanges 24 and their necks have inturned anges 26 to provide openings for the vvalve stems of the valve units 29 with associated nger pieces 31 with notches 30. In these figures, the ridge 13'of Fig. 4 is omitted for the valve unit maybe introduced through the bottom of the container and press tted into the neck to permanently mount the unit in position.

The foregoing detailed description sets forth its preferred practical form. It embodies numerous features, certain of which may be employed without necessarily employing all. The invention is therefore to be understood as not limited to the specic showings of the accompanying drawings but is to be understood as fully commensurate with the appended claims.

Having thus fully described' the invention, what I claim as new and desire to secure by Letters Patent is:

l. A nylon container body having a peripheral wall, and a plurality of beads extending in the direction and for the greater portion of the depth of said body and integral with said wall and spaced apart about the latter, the cross sectional area of those portions of the wall between the beads being of the order `of IVe-3% times the cross sectional area of the beads.

2. A nylon container body according to claim 1, wherein those portions of the wall between the beads are of substantially uniform thickness.

3. A nylon container body according to claim 1, where in the beads are spaced apart at uniform distances about the body.

4. A nylon container body according to claim l, wherein different portions of the depth of the container body are of different cross sectional areas with the beads and interposed wall sections correspondingly proportioned.

5. A nylon container body according to claim 1, wherein the container body is tapered in the direction of its depth and the beads are correspondingly tapered in the same direction. p

6. A nylon container body according to claim 1, wherein all of the beads are of substantially the same cross sectional area at each cross axial plane in the height of the upright body and are uniformly spaced apart around the Wall of the body.

7. A nylon container body according to claim 1, wherein the Wall thickness at one side of the container body is less than the wall thickness at the opposite side thereof.

8. A nylon container body according to claim l, wherein the inner and outer surfaces of the peripheral Wall of the container body are cross axially eccentric to one another.

9. A nylon container body having a peripheral wall which is thinner at one side of the body than at the opposite side thereof and tapering in thickness from the thinner to the thicker side to form a safety valve at the thinner side. i

10. A nylon container body according to claim 9, in combination with an outlet nozzle supported on they container body and pointing in the direction of the inner side thereof.

l1. A nylon container body having a peripheral wall the inner surface of which is eccentric to theouter surfface of said wall, whereby the Wall thickness at one side of the body is of less thickness than at the opposite side thereof.

l2. A nylon container body according to claim 11, in combination with an outlet nozzle supported on the container body and pointing in the direction of the thinner side thereof. v

13. A nylon container body having a peripheral wall with integral beads extending in the direction of the depth of said body and spaced apart peripherally of the body, with one section of the peripheral wall between two ad,-l

tional area of al1 of the beads.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 2,799,435 July 16 1957 Robert Henry Abplanalp It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 61, for "inner side" read --thinner side.

Signed and sealed this 18th day of February 1958.

(SEAL) Attest: KARL H. AXLINE R BER Attest-.ing Officer 0 T C WATSON Ccmmissioner of Patents

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