CA2364050A1 - Co-injection methods using endothermic-blowing agents and products made therefrom - Google Patents
Co-injection methods using endothermic-blowing agents and products made therefrom Download PDFInfo
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- CA2364050A1 CA2364050A1 CA002364050A CA2364050A CA2364050A1 CA 2364050 A1 CA2364050 A1 CA 2364050A1 CA 002364050 A CA002364050 A CA 002364050A CA 2364050 A CA2364050 A CA 2364050A CA 2364050 A1 CA2364050 A1 CA 2364050A1
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- Prior art keywords
- core mixture
- flow
- mold cavity
- outer material
- blowing agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47C—CHAIRS; SOFAS; BEDS
- A47C5/00—Chairs of special materials
- A47C5/12—Chairs of special materials of plastics, with or without reinforcement
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
- B29B7/7404—Mixing devices specially adapted for foamable substances
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
- B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
- B29C44/0461—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities by having different chemical compositions in different places, e.g. having different concentrations of foaming agent, feeding one composition after the other
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
- B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
- B29C44/0492—Devices for feeding the different materials
Abstract
The invention provides a method of co-injection molding. The method includes mixing a plastic inner material and an endothermic-blowing agent to form a core mixture.
A plastic outer material is injected from a first injection unit into a co-injection manifold to create a flow of outer material therethrough. The core mixture is injected from a second injection unit into the co-injection manifold to create a flow of core mixture therethrough.
The flow of the outer material and the flow of the core mixture are then controlled through the co injection manifold and into a mold cavity. The core mixture expands as heat is provided for the endothermic-blowing agent to absorb.
A plastic outer material is injected from a first injection unit into a co-injection manifold to create a flow of outer material therethrough. The core mixture is injected from a second injection unit into the co-injection manifold to create a flow of core mixture therethrough.
The flow of the outer material and the flow of the core mixture are then controlled through the co injection manifold and into a mold cavity. The core mixture expands as heat is provided for the endothermic-blowing agent to absorb.
Description
CO-INJhC:'1~ON MFTHODS USll~IG ENDO'T~IZMrC B~OWINC
At~H'.'N'TS AND PRODUCTS MADE TII>rltEFROM
C1ZOSS-R F Rh rNCIr TO RELATED A PPLT('~ a T I ( 1 N
This application claim3 pziority ux<der 35 U.S.C. 5 1 ) y tn l l.S, provisional application serial ao. 60/250,222 filed on November 30. 2000, which is hc«sby fully incorporated by reference.
FIELD OF TIC 1NVI;NT10N
t l) The invention rclatas to co-iajcction-moldimg methods, and more paitrcutarly to co-injection-iuuhling nicthods using cndotlnermic-blowing agents. 'l~hP methods compz~ise injocting two difyorent cnaterialc, typicahy an outer-akin material, and an innez~-c:orc material incorporating as endothermic-hlnwing agent, into a biuglc-cavity or multi-cavity mold. The invention also relates to them~oplastic au~ticlcs aus resins nnade froxt~ those matexi.alc and methods.
DACKCROUND OF TF~ INV~?N'T't~
Iu co-inEjoctioa mothods, a co injection manifold receives material, usually thez~mo-plastic, from two different injection units and rnmhines the two materials into a si.uxlc stream tk~at flows into a mold or die. The manifold allows one malciial to be co-molded inside another during a single cycle, Tha eo-il~jection mauiCold is thus located. between the ir~eetion units anti the mold. A typical cu-iyection manifold is axed to the injection units.
Exothermic-blowing a~gauts liave been incorporated into thermo-plastics in mono i»,jection ntulvLu~g metliods and in other injection moldi,zrg methods. A
blowang agent is a ~uLstaucc incorporated into a mixture for the purpose ofproducing a foam. But the use of c~othernnic blowing agents in mono-injecfi~nn-molding methods has been l.imilr~l to the production of end products, for which aesthe'dc Concerns do nor, apply_ Li other words, using exothesmi~ hlnwing agents in eor~junctiun with co-W jcctxon methods yielde aesthetic and other problems for the fulluwilig reasons.
First, using Cxull~wmic-blowing agents in the pore material produces ~meven bluwiuR, vrliich may cause voids in certain inner areas ofthr rams being produced.
Decausc the blowing agent is exothermic, heat e~rolves unevenly during the fuam~iug reaction, which accounts for the uneven blowing and the formaliuu of voids in tbc core material.
At~H'.'N'TS AND PRODUCTS MADE TII>rltEFROM
C1ZOSS-R F Rh rNCIr TO RELATED A PPLT('~ a T I ( 1 N
This application claim3 pziority ux<der 35 U.S.C. 5 1 ) y tn l l.S, provisional application serial ao. 60/250,222 filed on November 30. 2000, which is hc«sby fully incorporated by reference.
FIELD OF TIC 1NVI;NT10N
t l) The invention rclatas to co-iajcction-moldimg methods, and more paitrcutarly to co-injection-iuuhling nicthods using cndotlnermic-blowing agents. 'l~hP methods compz~ise injocting two difyorent cnaterialc, typicahy an outer-akin material, and an innez~-c:orc material incorporating as endothermic-hlnwing agent, into a biuglc-cavity or multi-cavity mold. The invention also relates to them~oplastic au~ticlcs aus resins nnade froxt~ those matexi.alc and methods.
DACKCROUND OF TF~ INV~?N'T't~
Iu co-inEjoctioa mothods, a co injection manifold receives material, usually thez~mo-plastic, from two different injection units and rnmhines the two materials into a si.uxlc stream tk~at flows into a mold or die. The manifold allows one malciial to be co-molded inside another during a single cycle, Tha eo-il~jection mauiCold is thus located. between the ir~eetion units anti the mold. A typical cu-iyection manifold is axed to the injection units.
Exothermic-blowing a~gauts liave been incorporated into thermo-plastics in mono i»,jection ntulvLu~g metliods and in other injection moldi,zrg methods. A
blowang agent is a ~uLstaucc incorporated into a mixture for the purpose ofproducing a foam. But the use of c~othernnic blowing agents in mono-injecfi~nn-molding methods has been l.imilr~l to the production of end products, for which aesthe'dc Concerns do nor, apply_ Li other words, using exothesmi~ hlnwing agents in eor~junctiun with co-W jcctxon methods yielde aesthetic and other problems for the fulluwilig reasons.
First, using Cxull~wmic-blowing agents in the pore material produces ~meven bluwiuR, vrliich may cause voids in certain inner areas ofthr rams being produced.
Decausc the blowing agent is exothermic, heat e~rolves unevenly during the fuam~iug reaction, which accounts for the uneven blowing and the formaliuu of voids in tbc core material.
Second, and somewhat related, ir. is difficult to keep lha axotltermic-blowing agent homogenized within the: roes material dozing production. A~ a ~osult, whey the exothermic-blowing agent is mixed wily flit inner-core material, a heterogeneous mixhire tends io form, making il ditGcult to pmducc a high quality end product. For example, one pant cycle may produce a part exhibiting high pockets of potency why le a subsequent part cycle array produce a part exhibiting weaker pockets of potency. Keeping the blowing agent homogenized is critical to providing nnnsistent "pall feel" arid structural. ilitagiity to the end product. "Part feel" descrihes the physical charaetertstics of ILG
product, including how a part ~rrls when touched by the hands of a cu«stuner. Overall, it i9 difficult to 1 t~ rc~ylate the amount of and hu~~lo~cniae the liquid-exothermic blowing agent being introduced info llxrs core nr~aterial bctwaon part cycles while producing pmdnrt5.
Tlsird, using cxothornnic-blowing agents results in izrpylar and inconsistent pressure being exerted on the outside walls of the part after removal from the die.
ConFSequently, part size and shape are affected and many parts generdled Lhotoh'om need to be scrapped. Gontro).liztg the rressure that the blowing agcml wcrals un flit outside walls of the part after it is remtoved from the uwkl pa'uduccs a part having a muador, fiie~ndlier ''part feel." A related problEUn a,»uciated with adding exothermic-blowing agents to core rridlGii8ls is that these blowing agents toed to migrate toward the surfaee or saran of the part, thereby aifoeting the aesthetic appearance ofthe mrtare. 'This has limited the use of exotho~znic blowing agents for application in rartc that are not aesthetically demvandiux.
Finally, when exnthermic~blowing agents are used, slight lr~upomturo changes and variations msn It yn anmplieations in part sizes and pan cycle. hi otlicr words, the exothermic-blowing agents arc nut very versatile, and require uniform, constant Lemperatures W pru~lucG a cousisteat, quality end product. Minor temperature changes au.~l modifications arc often required during coring processes to overcome aesthetie, size, or cycle issues. As a recall, the use o~ exothoxtr~ic-blowing agPnrc in these ix~jection mulvli~y methods is limited.
SIJNIMA~'Y OF 'THE 17NYL''NTION' The pr.ese~nt iuventioa addresses the3o zee~da by providing eo-i~jeetioa metbncis that CLlll.lloy endothermic-blowing agents which absorb heat during the co-in~eetinn process.
Aocordingly, the invention providP~ a method of co-injection molding lhtu, iududes Mixing $ plastic inner material az~d an endothermic blowing agout iu fom a core mixture.
A plastic outer material is injected 8om a farsl lIl~GI:LIVAI 111111 into a co-injection manifold to create a flow of outer material thereihrough. Tlie core mixture is injected from a second injection omit into fihe co-insjectiton manifulet to croate a flow of oore mixture therethmngh.
The flow ~f the outer material and tho flow of tho core mixture are then ~.nntrolled through the co-in~jeeTlon mauiCuld and into a mold cavity. The core mixtmre is thereby co-illjecliuu muldCd inside the outer material. The core mixW re expands as heat is provided for the endothermic-blowing agent to absorb.
In another aspect, the present invention also provides co-ir~.jectcd plastic articles manufactured by co-injectynn processes. The co-izijcution processes iaelude melting an inner matPria.l and an endothermic-blowing agont to foam a ovre mixture, injecting a 1(1 riastic outer material Crorll a ;F~rst injection unit through a oo-iajeGti~n manifold and into a mold 4avity, and injecting the oore mixture froxxl a secox<r1 injection unlit through ~lhc w-injcctivn manifold and into the mold cavity, thereby Co-it~ectlon muldiug at least a portion of the core mixture iaside the oufPr material in the mold cavity. The core mixture expands when heat is providesri for the endothermio-bluwiug agent thorcia to ab3orb.
Oace the 15 outer mat~a.l and core miXtures ate allowed to cool in the mold cavity, a co-iajected plastic article fs formed. About 20 to 45 percent by volume of the article is inner material and about 0.1 co 4.0 percent by,rolume oFthe inner material is en.ci~rhermic-blowing maul.
In another aspect, the invention providrs~ a method for manut~ctuflnK ~
engineering-grade resin. The method includes adding a~n rntlullier'iuic-blowing agent to an 20 inner material, eXpOSltlg 1'hP hlowing agent and inner malrrial to a tcnnperaturc botween about 3t)Il-filltl° F and a pressure betwectr about 5,000-25,000 PSI to fozm a cure mixture.
An outer thermoplastic material is it~jrx.~tal from a first injection unit through a co-injection rrtanifold and tutu a mold cavity, and the core mixture is inj ected from a second irij ection unit (Ltuugli flit co-injection manifold and into the mold cavity to create the resin. 'TIiG
2S outer material insulates the core mixilu-e in the resin, and xhe resin is capablC ur fvrmizag a plastic article upon being cooled.
The present invPnti~n also provides for a method of co-injection molding including mixing an inner material and an endulhc~uuc-blowing agent to fortrx a pore mixture. The method also includes conQOllir~ tLe flow of the outer material and the core mixh~rr 30 through a cu-iujtction manifold and into a. mold cavity in order to rn-mold the core ruixlure inside the outer material. The core rna~cture expands when heat is provided Cur ll~e cndotherrnvic blowing agent to absorh.
In another aspect, tb.P rresent invention else pxovidcs for the maaufaature of co-injected plasti,r. articles produced by prvc:c~scs iucludung mixing an inner material and an eadothermic-blov~ring agent to form a wie mixture. The processes aleo include controlling the flow of the outer maierlal and lhc curt xuixture through a co injevtaon manifold and into a mold cavity iu urdw to co-mold the cure mixt~e inside the outer material. The core mixture exptuvls when heat is provided for the ez~dothernrAic-blowing agent to absorb.
Other foatures and advaatages of the inve:nti~n will become apparent lu those sldllod in tJne art upon review of the thl lowing detailed deserlptlon and claims.
Before embodimentF of the invention are explain~l u~ detail, it is to be understood that the invention is not limited in its applicaliuii lu the details of the composition and roncentLation of compuma~ts set forth in the following description. The invention i s capable of other embodiments sad of being practiced or being carried out in varAOUS ways.
Also, it is understood that the phraseology and terminology used herein is for the purpusC
of description and should not br regarded as limiting.
Unless explieytly stated otherwise, the order in wlricli flit steps or acts in the methods described hereiil are parfuuued, and nriore particularly, the ordor in which the steps or acts in t?ae mrlhwla claimed herein arc perform~d zrxay vary. Unless explicitly stalxd uiliC~ mist, just bxausc one step or act is listed or described befom another doe9 not u~sccssarily mean that stag or eat must be performed before the other.
H It I h:'F T~ ~C_ttlPTI9N OF Tl~ DRAIyV' GS
Fignrp 1 iR a cross-section view of a co-injcc;tiuu maufold that may be used in the methods ofthe present mVCLLIIUIA-Figure 2 ib a pot9pectivc view of a handle embodying the invention.
Figure 3 is a cross-sectional view taken along line 3-3 in Figure ~.
P'igurc 4 is a pcxapective view of a haadle for a wheelchair embodying the itlv~tioa.
Figure S is a perspective view of a toilet Seat embodyiirg, the invention.
fi gore 6 is a perspective view of tt picx:o of lawn furniture cmbvdyiag tho invention.
Figwo 7 is a cross-sectional viow tulc~ aloag lin~ 7-7 in Fig_ 6.
Figuro 8 is a perspective view of a steering wheel embodying the invention.
Figure 9 ie a cross-sectional view taken a.lcmg line 9-9 in Fig. 8.
Figure 10 is a rersrective view of a hood for a vehicle au~Lo~lyiug tlto iavcntion.
~~TATT Ep p8SC:1Z1~.''~(7N OF Tt~ f,Q
As used horein, the term "co-irlj action molding" is meamt to refer to a procPSa by which two like or dissimilar elastics (e.k,. an outer/skin nnaterial and an inner/eore material) originating from differrttt sources (c.g. injection units) are injected into a si~lglc mold during a single cycle, thereby co-molding the inner/cctre material in5iae the outer/~kin material. 'flm ro-injection of the plastics may he either simultaneous or sequential a5 fiutlicr described below.
A., used herein, the terms "outer-skin material," "skimnaterial" and "outer material" are synonymous. The outer-slap »te~riats suitable fvr use in the m~sthods of the invention and the plastic artiCleS au~l resins produced therefrom include, but are In >l1u way limited to, a variety of Synthetic thcrnzoplastio resins aad therrnor~astic polyesters. For ecatnple, rnlycarbot~.tcs (PC), polycarbonate polyterepbthalates (PCPT), pulyethylcnc terephthalates (PET), polycarbonate polyethylene te~rrrhthalates (PCPET), polybutylene terepht'tlalatcs (P13T), polycarbonate polybrttylene terephthalales (PCPDT), polypropylene, glass-filled polypropylene, nylons, "N e~RYL"t~ manufeceured by Greneral 8lectric and "XENO'Y"~ manutactttred by General Eloctlic axe all auituble for use as outer=Skin materials in the methods and atticlo~ described herein.
As used herein, tree terms "inner-core material," "core material" and "fnntr material" are syju7nymous. The inner-core miaterialc suitable fvr use iui tha methods of the invention au~l flit plastic articlee produced thereiirm include, but are iu no way limited to, a wide variety of thermoplastics. The inner-core material cuay comprise the a$sne matcriala found in tha outer akin-material. The inttor u~atcrial nzay also cozzxprise recycled, or ground-up, skin material or stein iuuterial that is di3colored or othezwi.sP aesthetically tanappealang. Tn other words, plastic articles mnde from the eo-injecrirm methods ~ioscribed herein, whivl~ do not meet product specifications, can be ground-up, and used as inner-core matcriisl. But the inner-core material must have a viscosity llxat is higher thcw that of the outer-skin material. In other words, tEte inner material crust be stiffer than the outer material to prevent the. imter material from "bluwiug out" the outer material.
Specific examples of care material includa pulypropylcncs and polystyrenes.
Tb.e; ynnez core material may also lincludG mcycled cndothermie-blowiung agemta.
As used hor~siu, a "single cycle" refers to one cycle of a co-i~jecLion app~untus, and comprises fwe steps: 1) eloping the mold; 2) co-injecting the plastics; 3) packing and holdi~~g, 4) cooling and 5) openiag the mold. A fllrcher daa~w iptiozt of those &ve steps directly fohows.
First, oloeiag the mold preparrc the mold for lttc plastic injection and builds el3mp toanage.
Second, eo-injeetlng the pl~tics can be either simultaneous or sequential.
'l~ypically, plastics axe injoclc~l tlwough a co-iajoction manifold and into the meld at tcmpcrm~c~s around 300-600° F and pressures of 5,000 to 7.~,1)11171;SI.
The co-injec;liuu maufold is typically looated between injection unity and a mold. .f~ typical cu-injection mfmi.fold iE fixed to the injection emits. IT.S. Patens No. 4,376,625 issued to Lckardt; U.S.
Patent No. 5,650,178 issued tn Bemis; and U.S. paten.l Nu. 5,891,381 issued to Bemis, each of wk~ich iS hereby incorporated by rc.Cr'a~eucc, disclose sui~tablo co injection manifolds lU and eo-injeetlon apparatuses which can be used to carry out the methods descrihed herein, U.S. Patent No. 4,376,625 discloses one e.cample of a co-in~eetion manifold mounted on an injection unit suitable for use mth the invention. Another injculiuu unit communioates with the co-injection manifold via a tube. The manifukl Las a fotwardly opening outlet, an anaual part axi ally behind or up5ttcs~uu of the outlet, and a cantral port axially behiad or nrstream of the annular port. ~nc iuijection unit communioates with the central port, and the other ~jec;liuu unit comununicatcs with the wnaular port. A valve member is movable bGlwescn a fully forward position blocking both of the ports, an u~tanucdiatc position blocking only the central port, and a rearward position clear of bout ports. In the fully forward position, nra material flows through the outlet and solo flit mold.
In the intenx~ediate position, only material from the annular port flows d,~~ougli the outlet and into the: mild. In the rearward posi#on, bvtL tuatmial from the annular port and nnaterial from Lhe central port flow LLruugh flit outlet and into the mold.
U.S. Patc~nl Nu. S,G50,178 illustrates another examplo of a co-injection a~Aratus, which is illusthatcd in hig. 1. The apparatus 10 comprises (see l~~ig. 1) a cn-injection manifold 30 mounted relative to the platen 14 The co-injection manifold 30 cutuptlscs a nozzle hvuaiag 18 haviag tbrward and rP,arward ends. The nv~.c,lG lluusing 34 is generally V-shaped and includes angttlarly spaced i~rst and secuu~l ui ~iglit and 1aft arms 22 and 26.
Each arm has a rearward end 30 and incluaCs au outwardly extending nrtounting portion i4. 'fhe nozzle housing 18 has au outlet 36 in its forward end, a fu~et inlet 38 in the rearward awl uC the fit~st arm 22, and a seear~d inlet ~2 in the rearward end ~t'the second arur 2G. The outlet 34 is located on a horizontal axis extending timm the forward to rcatwvard. Tha outlet 36 eommwnieates with a norrle ~6 That communicates with flit mold cavity islet 50, and ultimately thr: mntd 52 and mold cavity (tint shown). The inlets 3S and 42 eoxnmunicate with injec#on nozzles 54 and 58 uCmspcctivc injection uaits (not shown). Tn The illuslr~ttr~d constnzotion, the in~jectinn nozzle 54 iujccts the inner core matezial and llre~ nozzle 58 injects the outer skin material. TLv apparatus may also include a nozzle pW G2.
U.S. Patent No. 5,891, ~R I discloses auutlicr injcetion molding apparatus that can be used in conjunction with the meltiuds described herein. ?he apraratus ineludGa a first mold cavity having an inlet, a scwnd mold cavity having an inlest, a source of a fast material to be injected, n source of a aacond material tn he ixtjected, and a co-injcetion manifold. The mtu~ifold includes a nozzle hous,ng including a ri«t outlet adapted to commuuicatc with the fast mold cam.ty inlet atld a scwud outlet adopted to communicate with the second mold cavity inlet First and sCC:oiid spaced apart inlets are re:xpectively adapted to communicate with the first and second sources of material to he injected. A
fir3t passageway eoznmunicateb botwccn tho first inlet and the ttrat and Second outlets, and a second passageway corruuunicatos between the second inlet and the ~l and second outlets.
l S A.u additional manifold may alcn he located m thG cxlold itscl.~ lending into the mold cavity. Thus, the apparatiLSea used to parfuun the mothoda and make the rroduets described herein may use: a plurality of matilfolds. A wide vsiriety of co-injection apparatuses and e~-inject7ion mauifulds can be used in conjunction with the invenlivu, and should x~nt he limited by tilosc net forth above.
Agaill,1hG plastic co-imjeotaon can be either ximultaneous or sexaue~utial.
For simuhamcoua plastic oo inj action, a slon or outer material is it~j cctcd from n fast inj eetion unit (usually through a manifold sac h as those deseribcd above) and into a mold cavity.
The flow of the outer material into the mol~1 array then be slowed as an innex err core matenicil from a second ~urce of barrel i' iujc:cted into tho mold, (usually thmugh a w-injection manifold), along wil,h luc outer matorial. Iu other words, the outer aDd cure mixri~re may flow concurrcsntly or simultaneously into the mild cavity. Tl>is allows the core material lu be injected inside the outer material_ Subsequently, flit outer and core mtslo~ial flow oan be texmuiaated substantially simultaneously, or alternatively, the flow of Lhe core material may be stopp~i while the outer iuaterial continues to flow to finish off the pnxt. Alternatively, simultaneous plastic injection may comprise i~jeeting the outer material from a tizxt source info the mold cavity, than injecting a core material into the mold cavity such that core material aad outer nc~aterial sim« Itaneously enter Qtd mold cavity, tern>inating tl~e flow of the outer material while allowing 4tic curt material to continue to flow, terminating the flow of the core material, and resuu~ing and subsenuently irrrninating the flow ctf the oulcx material in order tn complete ll~o produotiorr of a part.
When nSing sequatrtial plastic co-in~ecrion, outer uaatcrial from a Srat source is rust injectRrl into the >uau.ifold to create a thw of out~,-r material into the mild arid the mold cavity. Tht now of outer material into the mold cavity is then stopped. Tlte outer material may fill approxii7uately 30-50 percent of I,he mold cavity. Subsequently, lire outer material fi'out a second source is used to 811 llic remainder of the mold cavity and fiai3lt the part, ctr alternatively, the outer material is iqjectcd into the mild cavity and toward the very e~ct of the plastic infection" the Duw of the outer material may be ~toppcd and the injection of the outer material resumed to provide a better eosizle4ic appearance to the end product.
After tlae co-injection of thp plastics, iho co-injected plastics are exposed to the third step in floc single cycle, x.e. the "pack sad hold." During the pack amt hold, the plessute is reduced to anywhere between around 400-x200 PSI and the ieua,pcrature is oleo ~,tadually reduced A c the plastic cools, it begins tv cont:ract. As a result, the reduced pressure is still mainT,aitled a~ud some additional plastic (either skim or outer material] may be introduced into iho mold. Fourth, after the "pack anal lxold," the pressure is iiirther reriuced and the Hart is cooled to around L00° F while the part remains in the mold cavity.
Finally, the mold is op~ned and the finished part is rcrnoved to complete the sin~;lo cycle.
Overall, "oo ~ir~jeetion molding" is meant tv encompass eo-injection itictltods wlicreby a core material enters 'the ruuld cavity wrapped in a hlanket of skin azaxvriah Tn otbcr words, two materials I~mn different sources are vubstaniially simultaaeouEly or oequentially ir~jeeted inlu a single mold during a ~eingle cycle. Co-injection rnoldiag, nn the other hand, is not meant to refer to thrtning a purl, cooling it, and then layering a material ovd~~ the cooled-part. Go-mjeetion mola.iug is also different tmm filling utxc l5 Cavity of a two-oavity mold with one malc~ial from one barrel aaci then filling the other cavity with a different material $'orn a second barrel. It is also nit meant to refer to processes that use gay as a core material and then let the gaq dissipate lu atmosphere-gas assist. Finally, en-ittjectiun moldiag does sot inr.,lude pmvidiztz; a previously-made part.
and then molding a surface partly or coraplntely thereovGr. In other words, co-injection mnldirlg i5 different from insert m.nlding or ovcrxuoldiag. None of theses processes provide the insulation blaaket the skin material provides in co-injection.
Tho methods provided by the uwcntion add a variety of endoth~tuic-blowing agents (deetcribed below] LO 111e CU!'C matGllSl as part ofthe ect-injection methods described above. '1''he term "foaming agent" or "blowing agPrtt" is used to Qescribc any substaacP
_9-which, a.lctne or iI1 combination with other substances, is capable of pmducir~g a cellular Structure 1n a pl~sli,v or rubber maEe. Thus, "foaming agents" aiui "Llovving agents"
include solublC solids that leave pores when. Irressure is rcloascd, soluble ~olide that leave pure when leached out, liguids which develop cells wheat they change to gases, sort chemical agents that de~c~mpose or react u~ulcr the influenco of heat to term a gas. An "endothermic-foaming agent" or "ctidothcsmic-blowing agent" is a ti~araing agent or blowing agent that absorbs licat. The endothermi~blowinE agent is added lu flit tort material before the cute material is injected in order t~ form a "core mixture". Tho core mixture Shuuld have a higher viscosity and stiffness as compa«d to the outer ekin mai,crirrls. This prcvente the core mixnme tom pruuuding thmugh the outer matenal, i.e., "blowing out." A number of endothermio-bluwiug agcats suitable for use in the methods described herein are described bcluw, rn no way should the description of these blowW g agents be rnn,~trued as limiting flit scopo of the invention. Any hlowing agent Laving emdothetmiC propt~rlies is suitablo.
Solid-ruetothcrmic-blowing agents are lyrically employed in Nellct form. The actuitl Llowing agent may dust a carrier Pellet, such as a luw-deas;jty polyethylene bead.
Liquid-blowing agents are generally employed in a pruNrictary carrier, such as a fatty aeict oster, a mineral oil or a polyol.
K,oown liquid foanning a&cnts include certain aliphatic az~d halogenated ~0 hydmcarbons, low boiling alcohols, ethers, ketones, and aromatic hydrocarbotrs, Chemical Fu~uniu~ agents raag~ from simple salts such as ammonium or sodium, bicarbu~le to complex nitrogen releasing agents, of which atubisformamidc is an important example.
Foaming agents are generally elassifictl as physical or ehomieal. ~.'hemical foaming ascents (generally soli~lb) undergo a chemical transforxaatinn when producing kas, while Physical foatnirig agents undergo a generally rwersible Physical clzauge of state, e.g., vaponizaliu~~.
Physical foaming agents include liquid agents. Lidui~l pliysical foaming agents iuiclude volatile liquids which prodnco gas thz'ough vapmiZation. Common liquid physical foaznins agents general ly include shortcha;u4 aliphatic hydrocarbons (CS to (_'.7) and their chlorinated and thioringted arialog5. Liquid physical foaming agents may he used oven' a wide temperature range in low pressure and atxaospheric processes, and are wiatly used to produce low dcnsi~y thcrmoplasticc, Eueh as foamed Polystyrene, due thcrmosct polymers, such as polyesters, epoxy, and polyurethane foam systems.
-I
Clicmical foaming agents comsuunly rcferxed to as blowing agents are generally solids that liberate ga~c(es) by mGSUis of a ahemnical ruction or druonzpositioa whea heated.
'fhcy are necessari ly selected for specific applications or yrocesscs based oa their decompositmn temperatures. In this regard, it is atnporlant to match the decrnmpositiuu tempenmre wills tho pmceaaing te~oreratw~e of Q~e polymer to be fozmed. ~f the polymer pmcesses at lamperaturae belo~uv that of the cheuiical foaming agent, little or uu foaming will occur. If the process tcimperaLUre is significozitly above the foaminx agent's da:ornpositioa temperature, poor (uYCrblown, ruptured) cell structure and surface skin quality wih likely result.
Chemical foaming or blownag agents may be either inorganic or organic. The most comzn~n inorganic foaming agent is sodium bicarbonate. Sodium biearh~nate is inexpensiv~, nuuflamtnable and begins to da;omposc of a low temreratu,re;
however, xt is used only to a vary limited extent in thertiroplastias, Dif~eerential thermal eualysis has sliown that sodium bicarbonate dec:uluposcs over a broad teroperaturc ~'ange sad this range is cndothetxnic, contributes to au open cell structure m the finished product, sad the released gas (carbon dioxide) diffuses through the polymCr at a much groater rata than nitrogen gas.
Emlutlicx~aaic chemical foaming or blowing agents are mostly mixtures of sudiutn bicarbonate and sodium hydrogen citrate. Tlie citrate is incorporated togethex with the sodium bicarbonate in order to i'~cililate a complete acid assisted decomposition reaction to pmduce carbon ~tioxide gds. The mixture is also avai table in various polymers as concentrates. ?he mixlw.'e is also available as a hydtophobi~ci acid and carbonate which i~c a free non-dusting powder.
Organic foamiag or blowing agents caa be utilized in moat polymer applic;ationa and pioccsscs. These compounds release Kas (usually nitrogen and/or ammonia) over a n:mow~ tcmporatiu'e raag~. 'fhe rate of gas evolution for a given chemical foaming or blowing agent is rietermixied by a tcmpcruture and times relationship, Applications for chemical teaming agents are gcnernlly divided into three arCras: low, medium and hrgh temperature processing polymers, There are numerous u~ganic foaming agents available that decotnpusc at various temperariires.
hi tliose co-injection methods, the enduthc~rrnic-blowing agents, in liquid ut solid fu.~~u, arc added to the inner-core material to form a core miWre preferably before the core mixture is iajeeted into the muhl., and morn preferably the core auixture is iajeeted into the manithld. Typically, those blowiag agents are added in atmount equal to about 0.1 to about 4 peteent by vulwuc of the pore material. lh-eferably, the vlowing agent is 0.5-3.0 percent by vuluwo of the corn material, and mare preferably, 1 _0-2_0 percent by volunne of the curC material. Typically, the cores material is about 20 to about HIS
percent by volume of the final part, with the remainder beinld skin material and any other imrurities.
When using liquid-endulhennio-blowing agents, a peristatlic-type pump nay be employed to introduce the blowing agent directly into the injection unit contttiuing the corn material. Peristatlic pwilps were originally employpri in the medical itAdustry in order to accurately admiuiater liquids to patients. Liquid hlovsritlg ageltts ac~G
prefcircd bocause a perialaltic voluznotric pump can be need to introduce llro blowing agont~ into the core material uniformly and consistently, In uQmr words, this metering provides hetter reliability and reTeatability than usiaig solid pellets or bonds. Pellets and beads may lc~~d to bunch, thes~hy inhibitiu~ uniform distribution into the core material.
Onc;o flit penixtatlic-type pump ~lGlivcrs the blowing agent into flap injection unit, lha liquid agont iE
integrated thcxaiu once the core material is melted (agaiIt at tempo~aturcs around 300-600°
F). A pmistatlic-type pump is only one example of an apparatus used to doliver a liquid Gndothczmic blowing agent tutu the injection unit.
Altonciatively, when solid-endolhcuxuc-blowing agonte ate used (usually in, pellet form as fiirthPr described above), a "weight sad locE feeder" may be used iv meter, weigh and feed the solid pellGh into the iz~joction unit containing the core material. Tu other wards, the feeder weighs the coro material and is programmed to provide x perccatago by volume of blowing agent to the core material C:onair manufactut~ss weight amd lose feedcis, while Millicron cells such feeders. Those of ordinruy s1Q11 is the tut will be familiar with "weight sad lflRR feeders" and olhe~ ways to dclivor the solid blowing agents into tho core material.
ixa nrdcr to trigger Ihc foamixg or blowing reaction, whprehy the core nnixtuxe comprising the endothrrr,u,ic-blowing agent and the inner-care material begins to expand, heat must bG piovidcd because the blowing agrnt is endothermic. Host can be provided in a va,~ioty ofmaiuicr3. First, the eadothermio-blowing axcut can absorb heat fronn the skin material after the skis material and core mixture hnva been ir~jccted into the mold. In other words, the innet material incorporatc-s the endothermic blowing agent., and enters the mold cavity wrappP~i in the skin alal,ciial. The skin material acts as an electric blanket of soft and an insulator, th~.~by pzoviding wr~ifornn heat exposure to the core mixluu~e. The skin material remains al a uniform temperature because: of its inhez~l iuisulatiag abilities.
Acwtdiugly, the surface of the rnolde~l Product exhibits a constant tcmperuturo for -1a-iuteractivts with the core trilXture, wliich providos the heat-activated-blowiag agent within the core material with a cuutl~olled exposure to teznperaiure. Oue of the benefits of unifornn temperature expusurc includes umtorm hlowing throughout the part. A
Iso, a redaction In ibe ratio of blowing agent to core material can be achieved because there is iio need to uYCrload the agent in a~n effort to cuiupcnaatc for cold poeacPt areas. Tha Lencfits of unifoma insulation are not available in mono-injection molding methods bccauac no skin material is users, which Cauads the internal temperphire of the product to vary.
Altonnatively, iiictional heal iuay be provided to indur:e the xbamitrg rcactioa. More particularly, frictional heat xnay be provided ac the core mixhu-c moves through manifold and is ultimately injocacd into the mold ZIl CUlltLaSt, by usiag mono-injection meltluds, plastics eontainiaE
exothermic blowing agents arc oxposed to a variety of temperatures during thp molding pruccss. I'or c~acamplc, in a hopper, tbF plastic drops into a fcod erection is which tempemtut~cs arc significantly higher than alrtbicut. In the metering secaion of the bars el, the pla~"tics are exposed to high temperaluAes in order to melt the rlastic. Finally, as the plastics enter the cavity of the mold, the temperature drops sygnificantly. That temperature howevrr, is ~mevenly appliCd i~a the mold because it is cooled by a series of water ehazin.olF which, even i~~ the brat molds, cool tbp plastic unevorxly. Agaia, this is much different from co-itijection molding is which the slGin lnatcrial acts as ail insulating blanket lu the core material.
Using an endoltrramic-blowing agent in cn-injection mrlL~ods provides several.
advantaEes over and addrcascs mercy of the prnhlems caused Ly using exothermic-blowing agents. Firsl, l)xe cost-per past is redured dues to reductions in eyole time cad the overall weight of lira material. Cycle times are reduced, in part, bccau,se the endotberrnic end-pivducts do not require as much "cool-down" as cxotharmie end-prvriucts aftez' being injected. Similarly, the 'rackiz~ and bolding" step of a ciagle cycle may nv longer bo neeessary_ Again, the endolheumic ngcata absorb heat, rather than f~ivG
offhcat.
Second, althuup~h endothermic-blowing agents are draiguod to activate at a sprcific te~rnpera'ture. The outor-skier material ias,alates the core tuixture comprising the 3U endpthGrilllc material at a uniform Specific maximuun temperature. Again, mono-injrc;tiun mctliods do not provide skin material, znakiug activation di~eult to control because of the lack of uniform heat. The Conirullcd post-meld blowing irlentlfied with using cndothermdc materials provides producih laving a more rouaded r"ntour. and cuusequcntly a better "part feel: ' Third, cmdotheTmic-Ulowing agents require heat to least, which means they withdraw nearly idcutical amounts of heat from all areas of the mold, thereby producing urnthrm blowink or Foaming throughout the part. In contrast, blowing nr foatninl;
tbtoughuul a part or product vanes dramatically whcn an exothermic blowing akent is used in iujcction methods. As a result. parts produced fronn endotbernnic-blowing agcu'rV
pusscss cvo~aly distributed plastic fur without the voids sn commonly associated with cxothezmic parts.
Another advanlagc to using endother~cnic-blowil~ agents is that psxts that do not meet pxoducliun staadarde can be grrnmd-up and rCuscd as core material. In contrast, it is di$ieult lu reuse exothermic parrF because not all of the exothermic agent aclivatcs in the ihiiuicr areas of these parts. Thus, o~ncG ground-up for reuse or recycling, 4tierc is no way lu coabne or segregate ground paaticles containing the non-activated-axothcncaic blowing agcat. Accordingly, reusing m rccycliag this materia) cart be very unpredictable. Often, reusing ground-up materials including exothermic results in flit product blowing up once the product leaVC~ flit mold at standard cycle tinge. Ixt uuntraxt, endothermic-blowing agents taud to fully activate during the processes dcscribcd herein, and therefore are entirely "spent." A,e a result, this material c:au be reground and reliahiy teusetl. ass tort material.
Endothermic-hlowiug agents also tend to remain homogeni~od when added to the inner-core material. Usink Gndothcrmic-blowing agents reduces cysts flints five to ten percemt and produces parts having stable sy~os cad profiles. Using eadothermic-blowing agents yield faster cycles by reduciag the need for Cx.letnal cooling because the emluthcrmio-blowing ageats ahsorb heal.
Other advantages associated with using cndothezmic foPming oz' bluwing agents over their exothermic cotmtc~~.ts iacluda shorter degassing cycles, 5u~aller cell; and smoother surfaces. Thests advantages yield products and purls having uniform physical properties and substantially less voids add areas of dense a~ad weak forming.
Using an endothermic-blowing agent results m products having i~mprovod structure amci insulation.
The methods deseribP~i herein can be used to produce a wide variety of $nal plastic apparatuses and cad rmducts, whicL will become apparent to one of ordinary skill in the art. For exatmple, thick and thin-walled handles for electric appliances can be produced using these methods. Mure specifically, handles the refr~geraturs, ovcas, etc.
(Fig. 2) can be made using the ruotliods described herein. Plastic h~audles for wheelchairs (Fig. 4) call also be raadc from thcso methods. AJ~~, plastic bonds (Fig. 10) for vehicles sneh as tractors asul lawn. mowers can also be aiadc, as well as toilet Seats (Fig.
5), lawn fi~umiW re (Fix. 7) and plastic steering wheels (Fig. 8). In the figures, outer n~atcrial is depicted as reference numeral 7I1, inner nna.tcrial as 74 and endothermic-blowing agent as 7lS. The real key to the pm~tuction of H.uy of these end pmducts is tha production of an engirteerinK-grade resin. The GuRiaccring Bade zPCin comprises the thazmoplastie-outer matraial, a thermoplastic-ilmcr material and an endotheruuc-blowing agent, and can be usod to pmduce <u~ unlimited amount ofmolde~l-plastic products, such as thobc described above.
Accordingly, these applications should. no way be constn~cci as limiting the scope of the iuventior~.
Using "XENOY"~ nnaterial (raanufacturcd by General >~lectric) as a. sha nnaterial, and eittira "XENOY'"~ regnnd, "XENOY"~ off specification material, ur a combination lhra~cof, as a sore material combined with an endothermic blowing agent, a lawn tractor hood can be co-xnjEx:ted at a siguificaxatly reduced price. The resultant hoods are every bit as a strong and outdoor-oxposurc resistant as a mono-injcc;lad part using exotb,rrniic-blowing agents. The significant advantage ofusing 1116 endothermic-blowing agent is that the siruetural iutcgnty of the part is not compruuused because of nearly perfect uniform blvwink u.Cthe core material. Nn area of flit hood is structurally compmmi'ed as would typically be found when acing an inbrawntly unevenly-blown exothermic-activated-foamed uorc.
fiver though the matciials (both skin and core) have virtually idcntivt~.l.
vtscosiheS
is this example, by rGd.ucing tho core melt temperature app~oximatoly SO
degree Fahrenheit, the p~stt is artificially stiffer, thereby maintaining the appropriate gtiffor uu~c requireracut of cv-injection molriing intact.
aamvlo 2 A plastic handle for a kitchen appliance was manufactured using a co-injection method. An endothetmicr-blowing agent was added to a core material (polypmpylenr/polyethylene) in an injection unit to form a core mixture.
Another injection unit was supplied with a glass-$lled w-polymer polypropylene skin malxtial.
ThG skin material. was injP.caed through a. co-injection manifold and into a mold from the injection unit. SubseqnPntly, the tale mixture was injected into tale ruold.
The skin material was iim'her iujectea to i'raish off the plastic handle. 'fha and plastic handle comrrised 7Z.6 prc~ont by volunne o~the skin materidh 27.3 perocat by voluane oi: the core material a,ud the rcmr~in.dor endothrrmi~-blowing ~x~nt.
product, including how a part ~rrls when touched by the hands of a cu«stuner. Overall, it i9 difficult to 1 t~ rc~ylate the amount of and hu~~lo~cniae the liquid-exothermic blowing agent being introduced info llxrs core nr~aterial bctwaon part cycles while producing pmdnrt5.
Tlsird, using cxothornnic-blowing agents results in izrpylar and inconsistent pressure being exerted on the outside walls of the part after removal from the die.
ConFSequently, part size and shape are affected and many parts generdled Lhotoh'om need to be scrapped. Gontro).liztg the rressure that the blowing agcml wcrals un flit outside walls of the part after it is remtoved from the uwkl pa'uduccs a part having a muador, fiie~ndlier ''part feel." A related problEUn a,»uciated with adding exothermic-blowing agents to core rridlGii8ls is that these blowing agents toed to migrate toward the surfaee or saran of the part, thereby aifoeting the aesthetic appearance ofthe mrtare. 'This has limited the use of exotho~znic blowing agents for application in rartc that are not aesthetically demvandiux.
Finally, when exnthermic~blowing agents are used, slight lr~upomturo changes and variations msn It yn anmplieations in part sizes and pan cycle. hi otlicr words, the exothermic-blowing agents arc nut very versatile, and require uniform, constant Lemperatures W pru~lucG a cousisteat, quality end product. Minor temperature changes au.~l modifications arc often required during coring processes to overcome aesthetie, size, or cycle issues. As a recall, the use o~ exothoxtr~ic-blowing agPnrc in these ix~jection mulvli~y methods is limited.
SIJNIMA~'Y OF 'THE 17NYL''NTION' The pr.ese~nt iuventioa addresses the3o zee~da by providing eo-i~jeetioa metbncis that CLlll.lloy endothermic-blowing agents which absorb heat during the co-in~eetinn process.
Aocordingly, the invention providP~ a method of co-injection molding lhtu, iududes Mixing $ plastic inner material az~d an endothermic blowing agout iu fom a core mixture.
A plastic outer material is injected 8om a farsl lIl~GI:LIVAI 111111 into a co-injection manifold to create a flow of outer material thereihrough. Tlie core mixture is injected from a second injection omit into fihe co-insjectiton manifulet to croate a flow of oore mixture therethmngh.
The flow ~f the outer material and tho flow of tho core mixture are then ~.nntrolled through the co-in~jeeTlon mauiCuld and into a mold cavity. The core mixtmre is thereby co-illjecliuu muldCd inside the outer material. The core mixW re expands as heat is provided for the endothermic-blowing agent to absorb.
In another aspect, the present invention also provides co-ir~.jectcd plastic articles manufactured by co-injectynn processes. The co-izijcution processes iaelude melting an inner matPria.l and an endothermic-blowing agont to foam a ovre mixture, injecting a 1(1 riastic outer material Crorll a ;F~rst injection unit through a oo-iajeGti~n manifold and into a mold 4avity, and injecting the oore mixture froxxl a secox<r1 injection unlit through ~lhc w-injcctivn manifold and into the mold cavity, thereby Co-it~ectlon muldiug at least a portion of the core mixture iaside the oufPr material in the mold cavity. The core mixture expands when heat is providesri for the endothermio-bluwiug agent thorcia to ab3orb.
Oace the 15 outer mat~a.l and core miXtures ate allowed to cool in the mold cavity, a co-iajected plastic article fs formed. About 20 to 45 percent by volume of the article is inner material and about 0.1 co 4.0 percent by,rolume oFthe inner material is en.ci~rhermic-blowing maul.
In another aspect, the invention providrs~ a method for manut~ctuflnK ~
engineering-grade resin. The method includes adding a~n rntlullier'iuic-blowing agent to an 20 inner material, eXpOSltlg 1'hP hlowing agent and inner malrrial to a tcnnperaturc botween about 3t)Il-filltl° F and a pressure betwectr about 5,000-25,000 PSI to fozm a cure mixture.
An outer thermoplastic material is it~jrx.~tal from a first injection unit through a co-injection rrtanifold and tutu a mold cavity, and the core mixture is inj ected from a second irij ection unit (Ltuugli flit co-injection manifold and into the mold cavity to create the resin. 'TIiG
2S outer material insulates the core mixilu-e in the resin, and xhe resin is capablC ur fvrmizag a plastic article upon being cooled.
The present invPnti~n also provides for a method of co-injection molding including mixing an inner material and an endulhc~uuc-blowing agent to fortrx a pore mixture. The method also includes conQOllir~ tLe flow of the outer material and the core mixh~rr 30 through a cu-iujtction manifold and into a. mold cavity in order to rn-mold the core ruixlure inside the outer material. The core rna~cture expands when heat is provided Cur ll~e cndotherrnvic blowing agent to absorh.
In another aspect, tb.P rresent invention else pxovidcs for the maaufaature of co-injected plasti,r. articles produced by prvc:c~scs iucludung mixing an inner material and an eadothermic-blov~ring agent to form a wie mixture. The processes aleo include controlling the flow of the outer maierlal and lhc curt xuixture through a co injevtaon manifold and into a mold cavity iu urdw to co-mold the cure mixt~e inside the outer material. The core mixture exptuvls when heat is provided for the ez~dothernrAic-blowing agent to absorb.
Other foatures and advaatages of the inve:nti~n will become apparent lu those sldllod in tJne art upon review of the thl lowing detailed deserlptlon and claims.
Before embodimentF of the invention are explain~l u~ detail, it is to be understood that the invention is not limited in its applicaliuii lu the details of the composition and roncentLation of compuma~ts set forth in the following description. The invention i s capable of other embodiments sad of being practiced or being carried out in varAOUS ways.
Also, it is understood that the phraseology and terminology used herein is for the purpusC
of description and should not br regarded as limiting.
Unless explieytly stated otherwise, the order in wlricli flit steps or acts in the methods described hereiil are parfuuued, and nriore particularly, the ordor in which the steps or acts in t?ae mrlhwla claimed herein arc perform~d zrxay vary. Unless explicitly stalxd uiliC~ mist, just bxausc one step or act is listed or described befom another doe9 not u~sccssarily mean that stag or eat must be performed before the other.
H It I h:'F T~ ~C_ttlPTI9N OF Tl~ DRAIyV' GS
Fignrp 1 iR a cross-section view of a co-injcc;tiuu maufold that may be used in the methods ofthe present mVCLLIIUIA-Figure 2 ib a pot9pectivc view of a handle embodying the invention.
Figure 3 is a cross-sectional view taken along line 3-3 in Figure ~.
P'igurc 4 is a pcxapective view of a haadle for a wheelchair embodying the itlv~tioa.
Figure S is a perspective view of a toilet Seat embodyiirg, the invention.
fi gore 6 is a perspective view of tt picx:o of lawn furniture cmbvdyiag tho invention.
Figwo 7 is a cross-sectional viow tulc~ aloag lin~ 7-7 in Fig_ 6.
Figuro 8 is a perspective view of a steering wheel embodying the invention.
Figure 9 ie a cross-sectional view taken a.lcmg line 9-9 in Fig. 8.
Figure 10 is a rersrective view of a hood for a vehicle au~Lo~lyiug tlto iavcntion.
~~TATT Ep p8SC:1Z1~.''~(7N OF Tt~ f,Q
As used horein, the term "co-irlj action molding" is meamt to refer to a procPSa by which two like or dissimilar elastics (e.k,. an outer/skin nnaterial and an inner/eore material) originating from differrttt sources (c.g. injection units) are injected into a si~lglc mold during a single cycle, thereby co-molding the inner/cctre material in5iae the outer/~kin material. 'flm ro-injection of the plastics may he either simultaneous or sequential a5 fiutlicr described below.
A., used herein, the terms "outer-skin material," "skimnaterial" and "outer material" are synonymous. The outer-slap »te~riats suitable fvr use in the m~sthods of the invention and the plastic artiCleS au~l resins produced therefrom include, but are In >l1u way limited to, a variety of Synthetic thcrnzoplastio resins aad therrnor~astic polyesters. For ecatnple, rnlycarbot~.tcs (PC), polycarbonate polyterepbthalates (PCPT), pulyethylcnc terephthalates (PET), polycarbonate polyethylene te~rrrhthalates (PCPET), polybutylene terepht'tlalatcs (P13T), polycarbonate polybrttylene terephthalales (PCPDT), polypropylene, glass-filled polypropylene, nylons, "N e~RYL"t~ manufeceured by Greneral 8lectric and "XENO'Y"~ manutactttred by General Eloctlic axe all auituble for use as outer=Skin materials in the methods and atticlo~ described herein.
As used herein, tree terms "inner-core material," "core material" and "fnntr material" are syju7nymous. The inner-core miaterialc suitable fvr use iui tha methods of the invention au~l flit plastic articlee produced thereiirm include, but are iu no way limited to, a wide variety of thermoplastics. The inner-core material cuay comprise the a$sne matcriala found in tha outer akin-material. The inttor u~atcrial nzay also cozzxprise recycled, or ground-up, skin material or stein iuuterial that is di3colored or othezwi.sP aesthetically tanappealang. Tn other words, plastic articles mnde from the eo-injecrirm methods ~ioscribed herein, whivl~ do not meet product specifications, can be ground-up, and used as inner-core matcriisl. But the inner-core material must have a viscosity llxat is higher thcw that of the outer-skin material. In other words, tEte inner material crust be stiffer than the outer material to prevent the. imter material from "bluwiug out" the outer material.
Specific examples of care material includa pulypropylcncs and polystyrenes.
Tb.e; ynnez core material may also lincludG mcycled cndothermie-blowiung agemta.
As used hor~siu, a "single cycle" refers to one cycle of a co-i~jecLion app~untus, and comprises fwe steps: 1) eloping the mold; 2) co-injecting the plastics; 3) packing and holdi~~g, 4) cooling and 5) openiag the mold. A fllrcher daa~w iptiozt of those &ve steps directly fohows.
First, oloeiag the mold preparrc the mold for lttc plastic injection and builds el3mp toanage.
Second, eo-injeetlng the pl~tics can be either simultaneous or sequential.
'l~ypically, plastics axe injoclc~l tlwough a co-iajoction manifold and into the meld at tcmpcrm~c~s around 300-600° F and pressures of 5,000 to 7.~,1)11171;SI.
The co-injec;liuu maufold is typically looated between injection unity and a mold. .f~ typical cu-injection mfmi.fold iE fixed to the injection emits. IT.S. Patens No. 4,376,625 issued to Lckardt; U.S.
Patent No. 5,650,178 issued tn Bemis; and U.S. paten.l Nu. 5,891,381 issued to Bemis, each of wk~ich iS hereby incorporated by rc.Cr'a~eucc, disclose sui~tablo co injection manifolds lU and eo-injeetlon apparatuses which can be used to carry out the methods descrihed herein, U.S. Patent No. 4,376,625 discloses one e.cample of a co-in~eetion manifold mounted on an injection unit suitable for use mth the invention. Another injculiuu unit communioates with the co-injection manifold via a tube. The manifukl Las a fotwardly opening outlet, an anaual part axi ally behind or up5ttcs~uu of the outlet, and a cantral port axially behiad or nrstream of the annular port. ~nc iuijection unit communioates with the central port, and the other ~jec;liuu unit comununicatcs with the wnaular port. A valve member is movable bGlwescn a fully forward position blocking both of the ports, an u~tanucdiatc position blocking only the central port, and a rearward position clear of bout ports. In the fully forward position, nra material flows through the outlet and solo flit mold.
In the intenx~ediate position, only material from the annular port flows d,~~ougli the outlet and into the: mild. In the rearward posi#on, bvtL tuatmial from the annular port and nnaterial from Lhe central port flow LLruugh flit outlet and into the mold.
U.S. Patc~nl Nu. S,G50,178 illustrates another examplo of a co-injection a~Aratus, which is illusthatcd in hig. 1. The apparatus 10 comprises (see l~~ig. 1) a cn-injection manifold 30 mounted relative to the platen 14 The co-injection manifold 30 cutuptlscs a nozzle hvuaiag 18 haviag tbrward and rP,arward ends. The nv~.c,lG lluusing 34 is generally V-shaped and includes angttlarly spaced i~rst and secuu~l ui ~iglit and 1aft arms 22 and 26.
Each arm has a rearward end 30 and incluaCs au outwardly extending nrtounting portion i4. 'fhe nozzle housing 18 has au outlet 36 in its forward end, a fu~et inlet 38 in the rearward awl uC the fit~st arm 22, and a seear~d inlet ~2 in the rearward end ~t'the second arur 2G. The outlet 34 is located on a horizontal axis extending timm the forward to rcatwvard. Tha outlet 36 eommwnieates with a norrle ~6 That communicates with flit mold cavity islet 50, and ultimately thr: mntd 52 and mold cavity (tint shown). The inlets 3S and 42 eoxnmunicate with injec#on nozzles 54 and 58 uCmspcctivc injection uaits (not shown). Tn The illuslr~ttr~d constnzotion, the in~jectinn nozzle 54 iujccts the inner core matezial and llre~ nozzle 58 injects the outer skin material. TLv apparatus may also include a nozzle pW G2.
U.S. Patent No. 5,891, ~R I discloses auutlicr injcetion molding apparatus that can be used in conjunction with the meltiuds described herein. ?he apraratus ineludGa a first mold cavity having an inlet, a scwnd mold cavity having an inlest, a source of a fast material to be injected, n source of a aacond material tn he ixtjected, and a co-injcetion manifold. The mtu~ifold includes a nozzle hous,ng including a ri«t outlet adapted to commuuicatc with the fast mold cam.ty inlet atld a scwud outlet adopted to communicate with the second mold cavity inlet First and sCC:oiid spaced apart inlets are re:xpectively adapted to communicate with the first and second sources of material to he injected. A
fir3t passageway eoznmunicateb botwccn tho first inlet and the ttrat and Second outlets, and a second passageway corruuunicatos between the second inlet and the ~l and second outlets.
l S A.u additional manifold may alcn he located m thG cxlold itscl.~ lending into the mold cavity. Thus, the apparatiLSea used to parfuun the mothoda and make the rroduets described herein may use: a plurality of matilfolds. A wide vsiriety of co-injection apparatuses and e~-inject7ion mauifulds can be used in conjunction with the invenlivu, and should x~nt he limited by tilosc net forth above.
Agaill,1hG plastic co-imjeotaon can be either ximultaneous or sexaue~utial.
For simuhamcoua plastic oo inj action, a slon or outer material is it~j cctcd from n fast inj eetion unit (usually through a manifold sac h as those deseribcd above) and into a mold cavity.
The flow of the outer material into the mol~1 array then be slowed as an innex err core matenicil from a second ~urce of barrel i' iujc:cted into tho mold, (usually thmugh a w-injection manifold), along wil,h luc outer matorial. Iu other words, the outer aDd cure mixri~re may flow concurrcsntly or simultaneously into the mild cavity. Tl>is allows the core material lu be injected inside the outer material_ Subsequently, flit outer and core mtslo~ial flow oan be texmuiaated substantially simultaneously, or alternatively, the flow of Lhe core material may be stopp~i while the outer iuaterial continues to flow to finish off the pnxt. Alternatively, simultaneous plastic injection may comprise i~jeeting the outer material from a tizxt source info the mold cavity, than injecting a core material into the mold cavity such that core material aad outer nc~aterial sim« Itaneously enter Qtd mold cavity, tern>inating tl~e flow of the outer material while allowing 4tic curt material to continue to flow, terminating the flow of the core material, and resuu~ing and subsenuently irrrninating the flow ctf the oulcx material in order tn complete ll~o produotiorr of a part.
When nSing sequatrtial plastic co-in~ecrion, outer uaatcrial from a Srat source is rust injectRrl into the >uau.ifold to create a thw of out~,-r material into the mild arid the mold cavity. Tht now of outer material into the mold cavity is then stopped. Tlte outer material may fill approxii7uately 30-50 percent of I,he mold cavity. Subsequently, lire outer material fi'out a second source is used to 811 llic remainder of the mold cavity and fiai3lt the part, ctr alternatively, the outer material is iqjectcd into the mild cavity and toward the very e~ct of the plastic infection" the Duw of the outer material may be ~toppcd and the injection of the outer material resumed to provide a better eosizle4ic appearance to the end product.
After tlae co-injection of thp plastics, iho co-injected plastics are exposed to the third step in floc single cycle, x.e. the "pack sad hold." During the pack amt hold, the plessute is reduced to anywhere between around 400-x200 PSI and the ieua,pcrature is oleo ~,tadually reduced A c the plastic cools, it begins tv cont:ract. As a result, the reduced pressure is still mainT,aitled a~ud some additional plastic (either skim or outer material] may be introduced into iho mold. Fourth, after the "pack anal lxold," the pressure is iiirther reriuced and the Hart is cooled to around L00° F while the part remains in the mold cavity.
Finally, the mold is op~ned and the finished part is rcrnoved to complete the sin~;lo cycle.
Overall, "oo ~ir~jeetion molding" is meant tv encompass eo-injection itictltods wlicreby a core material enters 'the ruuld cavity wrapped in a hlanket of skin azaxvriah Tn otbcr words, two materials I~mn different sources are vubstaniially simultaaeouEly or oequentially ir~jeeted inlu a single mold during a ~eingle cycle. Co-injection rnoldiag, nn the other hand, is not meant to refer to thrtning a purl, cooling it, and then layering a material ovd~~ the cooled-part. Go-mjeetion mola.iug is also different tmm filling utxc l5 Cavity of a two-oavity mold with one malc~ial from one barrel aaci then filling the other cavity with a different material $'orn a second barrel. It is also nit meant to refer to processes that use gay as a core material and then let the gaq dissipate lu atmosphere-gas assist. Finally, en-ittjectiun moldiag does sot inr.,lude pmvidiztz; a previously-made part.
and then molding a surface partly or coraplntely thereovGr. In other words, co-injection mnldirlg i5 different from insert m.nlding or ovcrxuoldiag. None of theses processes provide the insulation blaaket the skin material provides in co-injection.
Tho methods provided by the uwcntion add a variety of endoth~tuic-blowing agents (deetcribed below] LO 111e CU!'C matGllSl as part ofthe ect-injection methods described above. '1''he term "foaming agent" or "blowing agPrtt" is used to Qescribc any substaacP
_9-which, a.lctne or iI1 combination with other substances, is capable of pmducir~g a cellular Structure 1n a pl~sli,v or rubber maEe. Thus, "foaming agents" aiui "Llovving agents"
include solublC solids that leave pores when. Irressure is rcloascd, soluble ~olide that leave pure when leached out, liguids which develop cells wheat they change to gases, sort chemical agents that de~c~mpose or react u~ulcr the influenco of heat to term a gas. An "endothermic-foaming agent" or "ctidothcsmic-blowing agent" is a ti~araing agent or blowing agent that absorbs licat. The endothermi~blowinE agent is added lu flit tort material before the cute material is injected in order t~ form a "core mixture". Tho core mixture Shuuld have a higher viscosity and stiffness as compa«d to the outer ekin mai,crirrls. This prcvente the core mixnme tom pruuuding thmugh the outer matenal, i.e., "blowing out." A number of endothermio-bluwiug agcats suitable for use in the methods described herein are described bcluw, rn no way should the description of these blowW g agents be rnn,~trued as limiting flit scopo of the invention. Any hlowing agent Laving emdothetmiC propt~rlies is suitablo.
Solid-ruetothcrmic-blowing agents are lyrically employed in Nellct form. The actuitl Llowing agent may dust a carrier Pellet, such as a luw-deas;jty polyethylene bead.
Liquid-blowing agents are generally employed in a pruNrictary carrier, such as a fatty aeict oster, a mineral oil or a polyol.
K,oown liquid foanning a&cnts include certain aliphatic az~d halogenated ~0 hydmcarbons, low boiling alcohols, ethers, ketones, and aromatic hydrocarbotrs, Chemical Fu~uniu~ agents raag~ from simple salts such as ammonium or sodium, bicarbu~le to complex nitrogen releasing agents, of which atubisformamidc is an important example.
Foaming agents are generally elassifictl as physical or ehomieal. ~.'hemical foaming ascents (generally soli~lb) undergo a chemical transforxaatinn when producing kas, while Physical foatnirig agents undergo a generally rwersible Physical clzauge of state, e.g., vaponizaliu~~.
Physical foaming agents include liquid agents. Lidui~l pliysical foaming agents iuiclude volatile liquids which prodnco gas thz'ough vapmiZation. Common liquid physical foaznins agents general ly include shortcha;u4 aliphatic hydrocarbons (CS to (_'.7) and their chlorinated and thioringted arialog5. Liquid physical foaming agents may he used oven' a wide temperature range in low pressure and atxaospheric processes, and are wiatly used to produce low dcnsi~y thcrmoplasticc, Eueh as foamed Polystyrene, due thcrmosct polymers, such as polyesters, epoxy, and polyurethane foam systems.
-I
Clicmical foaming agents comsuunly rcferxed to as blowing agents are generally solids that liberate ga~c(es) by mGSUis of a ahemnical ruction or druonzpositioa whea heated.
'fhcy are necessari ly selected for specific applications or yrocesscs based oa their decompositmn temperatures. In this regard, it is atnporlant to match the decrnmpositiuu tempenmre wills tho pmceaaing te~oreratw~e of Q~e polymer to be fozmed. ~f the polymer pmcesses at lamperaturae belo~uv that of the cheuiical foaming agent, little or uu foaming will occur. If the process tcimperaLUre is significozitly above the foaminx agent's da:ornpositioa temperature, poor (uYCrblown, ruptured) cell structure and surface skin quality wih likely result.
Chemical foaming or blownag agents may be either inorganic or organic. The most comzn~n inorganic foaming agent is sodium bicarbonate. Sodium biearh~nate is inexpensiv~, nuuflamtnable and begins to da;omposc of a low temreratu,re;
however, xt is used only to a vary limited extent in thertiroplastias, Dif~eerential thermal eualysis has sliown that sodium bicarbonate dec:uluposcs over a broad teroperaturc ~'ange sad this range is cndothetxnic, contributes to au open cell structure m the finished product, sad the released gas (carbon dioxide) diffuses through the polymCr at a much groater rata than nitrogen gas.
Emlutlicx~aaic chemical foaming or blowing agents are mostly mixtures of sudiutn bicarbonate and sodium hydrogen citrate. Tlie citrate is incorporated togethex with the sodium bicarbonate in order to i'~cililate a complete acid assisted decomposition reaction to pmduce carbon ~tioxide gds. The mixture is also avai table in various polymers as concentrates. ?he mixlw.'e is also available as a hydtophobi~ci acid and carbonate which i~c a free non-dusting powder.
Organic foamiag or blowing agents caa be utilized in moat polymer applic;ationa and pioccsscs. These compounds release Kas (usually nitrogen and/or ammonia) over a n:mow~ tcmporatiu'e raag~. 'fhe rate of gas evolution for a given chemical foaming or blowing agent is rietermixied by a tcmpcruture and times relationship, Applications for chemical teaming agents are gcnernlly divided into three arCras: low, medium and hrgh temperature processing polymers, There are numerous u~ganic foaming agents available that decotnpusc at various temperariires.
hi tliose co-injection methods, the enduthc~rrnic-blowing agents, in liquid ut solid fu.~~u, arc added to the inner-core material to form a core miWre preferably before the core mixture is iajeeted into the muhl., and morn preferably the core auixture is iajeeted into the manithld. Typically, those blowiag agents are added in atmount equal to about 0.1 to about 4 peteent by vulwuc of the pore material. lh-eferably, the vlowing agent is 0.5-3.0 percent by vuluwo of the corn material, and mare preferably, 1 _0-2_0 percent by volunne of the curC material. Typically, the cores material is about 20 to about HIS
percent by volume of the final part, with the remainder beinld skin material and any other imrurities.
When using liquid-endulhennio-blowing agents, a peristatlic-type pump nay be employed to introduce the blowing agent directly into the injection unit contttiuing the corn material. Peristatlic pwilps were originally employpri in the medical itAdustry in order to accurately admiuiater liquids to patients. Liquid hlovsritlg ageltts ac~G
prefcircd bocause a perialaltic voluznotric pump can be need to introduce llro blowing agont~ into the core material uniformly and consistently, In uQmr words, this metering provides hetter reliability and reTeatability than usiaig solid pellets or bonds. Pellets and beads may lc~~d to bunch, thes~hy inhibitiu~ uniform distribution into the core material.
Onc;o flit penixtatlic-type pump ~lGlivcrs the blowing agent into flap injection unit, lha liquid agont iE
integrated thcxaiu once the core material is melted (agaiIt at tempo~aturcs around 300-600°
F). A pmistatlic-type pump is only one example of an apparatus used to doliver a liquid Gndothczmic blowing agent tutu the injection unit.
Altonciatively, when solid-endolhcuxuc-blowing agonte ate used (usually in, pellet form as fiirthPr described above), a "weight sad locE feeder" may be used iv meter, weigh and feed the solid pellGh into the iz~joction unit containing the core material. Tu other wards, the feeder weighs the coro material and is programmed to provide x perccatago by volume of blowing agent to the core material C:onair manufactut~ss weight amd lose feedcis, while Millicron cells such feeders. Those of ordinruy s1Q11 is the tut will be familiar with "weight sad lflRR feeders" and olhe~ ways to dclivor the solid blowing agents into tho core material.
ixa nrdcr to trigger Ihc foamixg or blowing reaction, whprehy the core nnixtuxe comprising the endothrrr,u,ic-blowing agent and the inner-care material begins to expand, heat must bG piovidcd because the blowing agrnt is endothermic. Host can be provided in a va,~ioty ofmaiuicr3. First, the eadothermio-blowing axcut can absorb heat fronn the skin material after the skis material and core mixture hnva been ir~jccted into the mold. In other words, the innet material incorporatc-s the endothermic blowing agent., and enters the mold cavity wrappP~i in the skin alal,ciial. The skin material acts as an electric blanket of soft and an insulator, th~.~by pzoviding wr~ifornn heat exposure to the core mixluu~e. The skin material remains al a uniform temperature because: of its inhez~l iuisulatiag abilities.
Acwtdiugly, the surface of the rnolde~l Product exhibits a constant tcmperuturo for -1a-iuteractivts with the core trilXture, wliich providos the heat-activated-blowiag agent within the core material with a cuutl~olled exposure to teznperaiure. Oue of the benefits of unifornn temperature expusurc includes umtorm hlowing throughout the part. A
Iso, a redaction In ibe ratio of blowing agent to core material can be achieved because there is iio need to uYCrload the agent in a~n effort to cuiupcnaatc for cold poeacPt areas. Tha Lencfits of unifoma insulation are not available in mono-injection molding methods bccauac no skin material is users, which Cauads the internal temperphire of the product to vary.
Altonnatively, iiictional heal iuay be provided to indur:e the xbamitrg rcactioa. More particularly, frictional heat xnay be provided ac the core mixhu-c moves through manifold and is ultimately injocacd into the mold ZIl CUlltLaSt, by usiag mono-injection meltluds, plastics eontainiaE
exothermic blowing agents arc oxposed to a variety of temperatures during thp molding pruccss. I'or c~acamplc, in a hopper, tbF plastic drops into a fcod erection is which tempemtut~cs arc significantly higher than alrtbicut. In the metering secaion of the bars el, the pla~"tics are exposed to high temperaluAes in order to melt the rlastic. Finally, as the plastics enter the cavity of the mold, the temperature drops sygnificantly. That temperature howevrr, is ~mevenly appliCd i~a the mold because it is cooled by a series of water ehazin.olF which, even i~~ the brat molds, cool tbp plastic unevorxly. Agaia, this is much different from co-itijection molding is which the slGin lnatcrial acts as ail insulating blanket lu the core material.
Using an endoltrramic-blowing agent in cn-injection mrlL~ods provides several.
advantaEes over and addrcascs mercy of the prnhlems caused Ly using exothermic-blowing agents. Firsl, l)xe cost-per past is redured dues to reductions in eyole time cad the overall weight of lira material. Cycle times are reduced, in part, bccau,se the endotberrnic end-pivducts do not require as much "cool-down" as cxotharmie end-prvriucts aftez' being injected. Similarly, the 'rackiz~ and bolding" step of a ciagle cycle may nv longer bo neeessary_ Again, the endolheumic ngcata absorb heat, rather than f~ivG
offhcat.
Second, althuup~h endothermic-blowing agents are draiguod to activate at a sprcific te~rnpera'ture. The outor-skier material ias,alates the core tuixture comprising the 3U endpthGrilllc material at a uniform Specific maximuun temperature. Again, mono-injrc;tiun mctliods do not provide skin material, znakiug activation di~eult to control because of the lack of uniform heat. The Conirullcd post-meld blowing irlentlfied with using cndothermdc materials provides producih laving a more rouaded r"ntour. and cuusequcntly a better "part feel: ' Third, cmdotheTmic-Ulowing agents require heat to least, which means they withdraw nearly idcutical amounts of heat from all areas of the mold, thereby producing urnthrm blowink or Foaming throughout the part. In contrast, blowing nr foatninl;
tbtoughuul a part or product vanes dramatically whcn an exothermic blowing akent is used in iujcction methods. As a result. parts produced fronn endotbernnic-blowing agcu'rV
pusscss cvo~aly distributed plastic fur without the voids sn commonly associated with cxothezmic parts.
Another advanlagc to using endother~cnic-blowil~ agents is that psxts that do not meet pxoducliun staadarde can be grrnmd-up and rCuscd as core material. In contrast, it is di$ieult lu reuse exothermic parrF because not all of the exothermic agent aclivatcs in the ihiiuicr areas of these parts. Thus, o~ncG ground-up for reuse or recycling, 4tierc is no way lu coabne or segregate ground paaticles containing the non-activated-axothcncaic blowing agcat. Accordingly, reusing m rccycliag this materia) cart be very unpredictable. Often, reusing ground-up materials including exothermic results in flit product blowing up once the product leaVC~ flit mold at standard cycle tinge. Ixt uuntraxt, endothermic-blowing agents taud to fully activate during the processes dcscribcd herein, and therefore are entirely "spent." A,e a result, this material c:au be reground and reliahiy teusetl. ass tort material.
Endothermic-hlowiug agents also tend to remain homogeni~od when added to the inner-core material. Usink Gndothcrmic-blowing agents reduces cysts flints five to ten percemt and produces parts having stable sy~os cad profiles. Using eadothermic-blowing agents yield faster cycles by reduciag the need for Cx.letnal cooling because the emluthcrmio-blowing ageats ahsorb heal.
Other advantages associated with using cndothezmic foPming oz' bluwing agents over their exothermic cotmtc~~.ts iacluda shorter degassing cycles, 5u~aller cell; and smoother surfaces. Thests advantages yield products and purls having uniform physical properties and substantially less voids add areas of dense a~ad weak forming.
Using an endothermic-blowing agent results m products having i~mprovod structure amci insulation.
The methods deseribP~i herein can be used to produce a wide variety of $nal plastic apparatuses and cad rmducts, whicL will become apparent to one of ordinary skill in the art. For exatmple, thick and thin-walled handles for electric appliances can be produced using these methods. Mure specifically, handles the refr~geraturs, ovcas, etc.
(Fig. 2) can be made using the ruotliods described herein. Plastic h~audles for wheelchairs (Fig. 4) call also be raadc from thcso methods. AJ~~, plastic bonds (Fig. 10) for vehicles sneh as tractors asul lawn. mowers can also be aiadc, as well as toilet Seats (Fig.
5), lawn fi~umiW re (Fix. 7) and plastic steering wheels (Fig. 8). In the figures, outer n~atcrial is depicted as reference numeral 7I1, inner nna.tcrial as 74 and endothermic-blowing agent as 7lS. The real key to the pm~tuction of H.uy of these end pmducts is tha production of an engirteerinK-grade resin. The GuRiaccring Bade zPCin comprises the thazmoplastie-outer matraial, a thermoplastic-ilmcr material and an endotheruuc-blowing agent, and can be usod to pmduce <u~ unlimited amount ofmolde~l-plastic products, such as thobc described above.
Accordingly, these applications should. no way be constn~cci as limiting the scope of the iuventior~.
Using "XENOY"~ nnaterial (raanufacturcd by General >~lectric) as a. sha nnaterial, and eittira "XENOY'"~ regnnd, "XENOY"~ off specification material, ur a combination lhra~cof, as a sore material combined with an endothermic blowing agent, a lawn tractor hood can be co-xnjEx:ted at a siguificaxatly reduced price. The resultant hoods are every bit as a strong and outdoor-oxposurc resistant as a mono-injcc;lad part using exotb,rrniic-blowing agents. The significant advantage ofusing 1116 endothermic-blowing agent is that the siruetural iutcgnty of the part is not compruuused because of nearly perfect uniform blvwink u.Cthe core material. Nn area of flit hood is structurally compmmi'ed as would typically be found when acing an inbrawntly unevenly-blown exothermic-activated-foamed uorc.
fiver though the matciials (both skin and core) have virtually idcntivt~.l.
vtscosiheS
is this example, by rGd.ucing tho core melt temperature app~oximatoly SO
degree Fahrenheit, the p~stt is artificially stiffer, thereby maintaining the appropriate gtiffor uu~c requireracut of cv-injection molriing intact.
aamvlo 2 A plastic handle for a kitchen appliance was manufactured using a co-injection method. An endothetmicr-blowing agent was added to a core material (polypmpylenr/polyethylene) in an injection unit to form a core mixture.
Another injection unit was supplied with a glass-$lled w-polymer polypropylene skin malxtial.
ThG skin material. was injP.caed through a. co-injection manifold and into a mold from the injection unit. SubseqnPntly, the tale mixture was injected into tale ruold.
The skin material was iim'her iujectea to i'raish off the plastic handle. 'fha and plastic handle comrrised 7Z.6 prc~ont by volunne o~the skin materidh 27.3 perocat by voluane oi: the core material a,ud the rcmr~in.dor endothrrmi~-blowing ~x~nt.
Claims (27)
1. A method of co-injection molding, the method comprising:
mixing a plastic inner material and an endothermic-blowing agent to form a core mixture;
injecting a plastic outer material from a first injection unit into a co-injection manifold to create a flow of outer material therethrough;
injecting the core mixture from a second injection unit into the co-injection manifold to create a flow of core mixture therethrough;
controlling the flow of the outer material and the flow of the core mixture through the co-injection manifold and into a mold cavity thereby co-injection moulding the core mixture inside the outer material; and expanding the core mixture by providing heat for the endothermic-blowing agent to absorb.
mixing a plastic inner material and an endothermic-blowing agent to form a core mixture;
injecting a plastic outer material from a first injection unit into a co-injection manifold to create a flow of outer material therethrough;
injecting the core mixture from a second injection unit into the co-injection manifold to create a flow of core mixture therethrough;
controlling the flow of the outer material and the flow of the core mixture through the co-injection manifold and into a mold cavity thereby co-injection moulding the core mixture inside the outer material; and expanding the core mixture by providing heat for the endothermic-blowing agent to absorb.
2. The method of claim 1, whereby providing heat for the endothermic-blowing agent to absorb occurs before the outer material and the core mixture are injected into the manifold.
3. The method of claim 1, whereby providing heat for the endothermic-blowing agent to absorb occurs after the outer material and the core mixture have been injected into the manifold.
4. The method of claim 1, whereby providing heat for the endothermic-blowing agent to absorb occurs while the outer material and the core mixture are being controlled through the manifold.
5. The method of claim 1, wherein the endothermic-blowing agent comprises a mixture of sodium bicarbonate and sodium hydrogen citrate.
6. The method of claim 1, wherein the endothermic-blowing agent includes at least one of aliphatic and halogenated hydrocarbons, low boiling alcohols, ethers, ketones, aromatic hydrocarbons and simple salts.
7. The method of claim 5, wherein the simple salts are selected from the group consisting of ammonium bicarbonate, sodium bicarbonate and azobisformamide.
8. The method of claim 1, whereby controlling the flow of the outer material and the flow of the core mixture comprises allowing the core mixture to enter the mold cavity only after the outer material enters the mold cavity, and then allowing the core mixture and the outer material to flow into the mold cavity concurrently.
9. The method of claim 8, whereby controlling the flow of the outer material and the flow of the core mixture further comprises stopping the flow of the core mixture into the mold cavity and the flow of the outer material into the mold cavity substantially simultaneously.
10. The method of claim 8, whereby controlling the flow of the outer material and the flow of the core mixture further comprises stopping the flow of the core mixture into the mold cavity before stopping the flow of the outer material into the mold cavity.
11. The method of claim 8, whereby controlling the flow of the outer material and the flow of the core mixture further comprises stopping the flow of the outer material after the outer material concurrently flows with the core mixture, thereby allowing the core mixture to remain flowing.
12. The method of claim 11, whereby controlling the flow of the outer material and the flow of the core mixture further comprises stopping the flow of the core mixture into the mold cavity, and resuming the flow of the outer material into the mold cavity.
13. The method of claim 1, whereby controlling the flow of the outer material and the flow of the core mixture comprises allowing the outer material to enter the mold cavity before tho core mixture, stopping the flow of the outer material, allowing the core mixture to enter the mold cavity thereafter, stopping the flow of the core mixture into the mold cavity, and resuming the flow of the core mixture into the mold cavity.
14. A co-injected plastic article manufactured by a co-injection process comprising:
melting an inner material and an endothermic-blowing agent to form a core mixture;
injecting a plastic outer material from a first injection unit through a co-injection manifold and into a mold cavity;
injecting the core mixture from a second injection unit through the co-injection manifold and into the mold cavity;
co-injection molding at least a portion of the core mixture inside the outer material in the mold cavity;
expanding the core mixture by providing heat for the endothermic-blowing agent therein to absorb; and allowing the outer material and core mixture to cool in the mold cavity, thereby forming a co-injected plastic article, wherein about 20.0 to 45.0 percent by volume of the article is inner materiel and about 0.1 to 4.0 percent by volume of the inner material is endothermic-blowing agent.
melting an inner material and an endothermic-blowing agent to form a core mixture;
injecting a plastic outer material from a first injection unit through a co-injection manifold and into a mold cavity;
injecting the core mixture from a second injection unit through the co-injection manifold and into the mold cavity;
co-injection molding at least a portion of the core mixture inside the outer material in the mold cavity;
expanding the core mixture by providing heat for the endothermic-blowing agent therein to absorb; and allowing the outer material and core mixture to cool in the mold cavity, thereby forming a co-injected plastic article, wherein about 20.0 to 45.0 percent by volume of the article is inner materiel and about 0.1 to 4.0 percent by volume of the inner material is endothermic-blowing agent.
15. The article of claim 14, wherein the co-injected plastic article is a steering wheel.
16. The article of claim 14, wherein, the co-injected plastic article is a hood for a vehicle.
17. The article of claim 14, wherein the co-injected plastic article is a toilet seat.
18. The article of claim 14, wherein the co-injected plastic article is lawn furniture.
19. The article of claim 14, whereby the method by which the article is made further comprises allowing the core mixture to enter the mold cavity only after the outer material enters the mold cavity, and thereafter allowing the core mixture and the outer material to flow concurrently into the mold cavity.
20. The article of claim 14, whereby the method by which the article is made further comprises allowing the core mixture to enter the mold cavity before allowing the core mixture to enter the mold cavity, stopping the outer material from entering the mold cavity, allowing the core mixture to enter the mold cavity thereafter, stopping the flow of the core mixture thereafter, and resuming the flow of the core mixture into the mold cavity.
21. A method for manufacturing an engineering-grade resin, the method comprising:
adding an endothermic-blowing agent to an inner material;
exposing the blowing agent and inner material to a temperature between about 600° F and a pressure between about 5,000-25,000 PSI to form a core mixture;
injecting an outer thermoplastic material from a first injection unit through a co-injection manifold and into a mold cavity;
injecting the core mixture from a second injection unit through the co-injection manifold and into the mold cavity to create the resin, the outer material insulating the core mixture in the resin, and the resin being capable of forming a plastic article upon being cooled.
adding an endothermic-blowing agent to an inner material;
exposing the blowing agent and inner material to a temperature between about 600° F and a pressure between about 5,000-25,000 PSI to form a core mixture;
injecting an outer thermoplastic material from a first injection unit through a co-injection manifold and into a mold cavity;
injecting the core mixture from a second injection unit through the co-injection manifold and into the mold cavity to create the resin, the outer material insulating the core mixture in the resin, and the resin being capable of forming a plastic article upon being cooled.
22. The method of claim 21, wherein 20-45 percent by volume of the resin is inner material and about 0.1-4.0 percent by volume of the inner material is endothermic-blowing agent.
23. The method of claim 22, wherein the blowing agent ie about 0.5 to 3.0 percent by volume of the inner material.
24. The method of claim 23, wherein the blowing agent is about 1.0-2.0 percent by volume of the inner material.
25. The method of claim 21, wherein the plastic article is at least one of a handle, a wheel chair handle, a toilet seat, a vehicle hood and lawn furniture.
26. The method of claim 21, wherein the endothermic-blowing agent is a mixture of sodium bicarbonate and sodium hydrogen citrate.
27. The method of claim 21, wherein the endothermic-blowing agent is selected from the group consisting of aliphatic and halogenated hydrocarbons, low-boiling alcohols, ethers, ketones, aromatic hydrocarbons and simple salts.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US25022200P | 2000-11-30 | 2000-11-30 | |
| US60/250,222 | 2000-11-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2364050A1 true CA2364050A1 (en) | 2002-05-30 |
Family
ID=22946835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002364050A Abandoned CA2364050A1 (en) | 2000-11-30 | 2001-11-30 | Co-injection methods using endothermic-blowing agents and products made therefrom |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US6964748B2 (en) |
| CA (1) | CA2364050A1 (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050183897A1 (en) * | 2004-02-24 | 2005-08-25 | Lear Corporation | Two-shot co-injected automotive interior trim assembly and method |
| US7871119B2 (en) | 2004-04-30 | 2011-01-18 | International Automotive Components Group North America, Inc. | Door trim panel with dual density bolster armrest and integrated components |
| US20060061127A1 (en) * | 2004-09-20 | 2006-03-23 | Emerling David M | Molded automotive visor |
| US20060068193A1 (en) * | 2004-09-29 | 2006-03-30 | Lear Corporation | Method and apparatus for making a trim panel with a self-skinning blown elastomer component |
| US20060066088A1 (en) * | 2004-09-30 | 2006-03-30 | Hier Michael J | Inflatable airbag cushion formed with a blown elastomer core and methods of using and manufacturing same |
| US7458631B2 (en) * | 2004-10-19 | 2008-12-02 | International Automotive Components Group North America, Inc. | Automotive armrest with soft feel and method of making the same |
| US7156437B2 (en) * | 2004-10-19 | 2007-01-02 | Lear Corporation | Automotive trim part with applique and method of making same |
| US20060082179A1 (en) * | 2004-10-19 | 2006-04-20 | Depue Todd L | Automotive trim assembly having impact countermeasures and method of making the same |
| US20060082109A1 (en) * | 2004-10-20 | 2006-04-20 | Hier Michael J | Method of making an automotive trim assembly having an integrated airbag door |
| US7458604B2 (en) * | 2004-10-20 | 2008-12-02 | International Automotive Components Group North America, Inc. | Automotive trim assembly having an integrated airbag door |
| US20060099395A1 (en) * | 2004-11-09 | 2006-05-11 | Cowelchuk Glenn A | Automotive interior trim assembly and method |
| US20060097544A1 (en) * | 2004-11-09 | 2006-05-11 | Cowelchuk Glenn A | Automotive interior trim assembly and method |
| US7108312B2 (en) * | 2004-11-09 | 2006-09-19 | Lear Corporation | Vehicle door trim bolster with multi-feel cover and method of making the same |
| US7192074B2 (en) * | 2004-11-10 | 2007-03-20 | Lear Corporation | Automotive compartment having an integrated spring mechanism and method of making the same |
| US20060216479A1 (en) * | 2005-03-22 | 2006-09-28 | Lear Corporation | Two-shot, co-injected trim panel |
| US7390184B2 (en) * | 2005-11-09 | 2008-06-24 | Centoco Plastics Limited | Dual injection manifold |
| US20100283308A1 (en) * | 2009-05-11 | 2010-11-11 | Knoll, Inc. | Co-injection molded chair |
| US8663514B2 (en) * | 2010-05-11 | 2014-03-04 | Knoll, Inc. | Gas-assisted co-injection molded chair |
| JP2014509240A (en) * | 2010-10-19 | 2014-04-17 | アイ２アイシー コーポレイション | Manufacturing apparatus and manufacturing method of object having change in particle concentration |
| DE102012022970A1 (en) * | 2012-01-13 | 2013-07-18 | Engel Austria Gmbh | Preparing a foamed plastic component, comprises injecting a to-be-processed plastic provided with a physical blowing agent including carbon dioxide and nitrogen into a mold cavity of an injection molding machine |
| KR20170029860A (en) * | 2015-09-08 | 2017-03-16 | 삼성전자주식회사 | Case for mobile phone and injection mold for the same |
Family Cites Families (105)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3530539A (en) * | 1968-02-02 | 1970-09-29 | Gellert Jobst U | Gate valve for injection molding machines |
| US4014966A (en) * | 1972-09-06 | 1977-03-29 | Robert Hanning | Method for injection molding a composite foamed body having a foamed core and a continuous surface layer |
| CH566207A5 (en) * | 1972-12-07 | 1975-09-15 | Siemag Siegener Masch Bau | |
| US3966372A (en) * | 1973-05-28 | 1976-06-29 | Asahi-Dow Limited | Injection molding apparatus for forming a composite, foam-skin, article |
| DE2346135C2 (en) * | 1973-09-13 | 1982-11-04 | Battenfeld Maschinenfabriken Gmbh, 5882 Meinerzhagen | Method and device for the injection molding of plastic moldings which consist of a filling layer made of a thermoplastic material and a covering layer made of another thermoplastic material which encloses it |
| US3981661A (en) * | 1973-11-01 | 1976-09-21 | Don Allen Taylor | Injection cylinder unit, mold and mold handling apparatus |
| US4129635A (en) * | 1973-12-28 | 1978-12-12 | Asahi-Dow Limited | Method for producing foamed moldings from synthetic resin materials |
| US4126291A (en) * | 1974-10-18 | 1978-11-21 | California Injection Molding Co., Inc. | Injection mold for elongated, hollow articles |
| US4083903A (en) * | 1974-10-18 | 1978-04-11 | California Injection Molding Co., Inc. | Method for molding elongated thin wall articles |
| US4067673A (en) * | 1975-09-02 | 1978-01-10 | Ex-Cell-O Corporation | Apparatus for injection foam molding |
| JPS53102960A (en) * | 1977-02-21 | 1978-09-07 | Asahi Chem Ind Co Ltd | Injection mold |
| US4124308A (en) * | 1977-06-21 | 1978-11-07 | Beloit Corporation | Sequential co-injection unit adapted for structural foam molding |
| US4268240A (en) * | 1978-01-06 | 1981-05-19 | Husky Injection Molding Systems | Actuating mechanism for gate valve of injection nozzle |
| US4213751A (en) * | 1978-06-06 | 1980-07-22 | The Continental Group, Inc. | Valve gate mechanism for injection molding |
| US4279582A (en) * | 1979-04-02 | 1981-07-21 | Incoe Corporation | Method and apparatus for individual control of injection mold shut-off bushings |
| US4219323A (en) * | 1979-05-09 | 1980-08-26 | The Broadway Companies, Inc. | Self-compensating hot manifold link |
| US4315724A (en) * | 1979-12-19 | 1982-02-16 | Kamaya Kagaku Kogyo Co., Ltd. | Process and machine for multi-color injection molding |
| US4333629A (en) * | 1980-03-11 | 1982-06-08 | Pepsico, Inc. | Floating manifold for multi-cavity injection mold |
| DE3020122C2 (en) * | 1980-05-27 | 1984-04-26 | Battenfeld Maschinenfabriken Gmbh, 5882 Meinerzhagen | Circuit arrangement for metering gaseous or liquid substances, in particular physical blowing agents, into a flowable melt made of thermoplastic material |
| DE3025597C2 (en) * | 1980-07-05 | 1984-06-14 | Battenfeld Maschinenfabriken Gmbh, 5882 Meinerzhagen | Injection head for injection molding of multi-layer molded parts made of two different plastics that can be introduced from two separate injection cylinders |
| DE3031333C2 (en) * | 1980-08-20 | 1983-07-14 | Battenfeld Maschinenfabriken Gmbh, 5882 Meinerzhagen | Method and device for adjusting the wall thickness of a hose extruded from thermoplastic material |
| JPS5910899B2 (en) * | 1981-12-02 | 1984-03-12 | 世紀技研株式会社 | Cap to prevent accumulation in runnerless molds |
| DE3238090A1 (en) * | 1982-10-14 | 1984-04-19 | Battenfeld Maschinenfabriken Gmbh, 5882 Meinerzhagen | PLASTIC MOLDED BODY |
| US5523045A (en) * | 1983-04-13 | 1996-06-04 | American National Can Company | Methods for injection molding and blow-molding multi-layer plastic articles |
| US4497621A (en) * | 1983-04-13 | 1985-02-05 | American Can Company | Apparatus for simultaneously driving valve means through co-injection nozzles of a multi-cavity injection molding machine |
| US4934915A (en) * | 1983-04-13 | 1990-06-19 | American National Can Company | Apparatus for injection molding multi-layer articles |
| US4925100A (en) * | 1983-04-13 | 1990-05-15 | American National Can Company | Methods and apparatus for injection molding and injection blow molding multi-layer articles, and articles made thereby |
| US4712990A (en) * | 1983-04-13 | 1987-12-15 | American Can Company | Apparatus for injection molding and injection blow molding multi-layer articles |
| US4946365A (en) * | 1983-04-13 | 1990-08-07 | American National Can Company | Apparatus for injection molding and injection blow molding multi-layer articles |
| US5037285A (en) * | 1983-04-13 | 1991-08-06 | American National Can Company | Apparatus for injection molding and injection blow molding multi-layer articles |
| JPS6059127B2 (en) | 1983-04-30 | 1985-12-24 | 株式会社名機製作所 | Injection molding machine for multilayer molded bodies |
| EP0135798B1 (en) * | 1983-09-03 | 1989-03-15 | MASCHINENFABRIK HENNECKE GmbH | Multiple nozzle bringing together at least two free-flowing reactants for the preparation of a free-flowing reaction mixture which reacts into plastic, in particular into foamed plastic |
| US4657496A (en) * | 1984-06-04 | 1987-04-14 | Gifu Husky Co., Ltd. | Hot-runner mold for injection molding |
| US4588367A (en) * | 1984-07-16 | 1986-05-13 | Husky Injection Molding Systems Ltd. | Hot runner manifold for injection molding machine |
| US4682945A (en) * | 1984-07-16 | 1987-07-28 | Husky Injection Molding Systems Ltd. | Thermal insulating and expansion assembly for injection molding machine |
| JPS6211621A (en) * | 1985-07-10 | 1987-01-20 | Canon Inc | Injection molding machine |
| DE3532996A1 (en) * | 1985-09-16 | 1987-03-26 | Battenfeld Fischer Blasform | EXTRUSION HEAD |
| US4775308A (en) * | 1986-05-12 | 1988-10-04 | Husky Injection Molding Systems, Ltd. | Nozzle for coinjection of hollow articles and preforms |
| US4717324A (en) * | 1986-05-12 | 1988-01-05 | Husky Injection Molding Systems, Inc. | Coinjection of hollow articles and preforms |
| US4808101A (en) * | 1986-05-12 | 1989-02-28 | Husky Injection Molding Systems Ltd. | Tri-injection of hollow articles |
| US4931234A (en) * | 1986-05-12 | 1990-06-05 | Husky Injection Molding Systems Ltd. | Coinjection of hollow articles and preforms |
| GB8616460D0 (en) * | 1986-07-05 | 1986-08-13 | Metal Box Plc | Manufacture of articles |
| US4806294A (en) | 1986-09-18 | 1989-02-21 | Enron Chemical Company | Method of making a foam injection molded article |
| DE3632185A1 (en) * | 1986-09-23 | 1988-03-31 | Battenfeld Maschfab | DEVICE FOR PRODUCING PLASTIC MOLDED BODIES |
| EP0297158A1 (en) * | 1987-07-01 | 1989-01-04 | Battenfeld GmbH | Process for producing multilayer moulded articles from thermoplastic synthetic material |
| US5169648A (en) * | 1987-10-09 | 1992-12-08 | Battenfeld Gmbh | Apparatus for injection molding articles of thermoplastic materials |
| DE3735099A1 (en) * | 1987-10-16 | 1989-04-27 | Battenfeld Gmbh | METHOD AND DEVICE FOR PRODUCING MULTILAYER MOLDED PARTS |
| US4957682A (en) * | 1988-01-19 | 1990-09-18 | Kamaya Kagaku Kogyo Co., Ltd. | Method of injection molding a three-layered container |
| JPH01252003A (en) * | 1988-03-31 | 1989-10-06 | Kyowa Denki Kagaku Kk | Reflector for parabolic antenna for satellite broadcasting reception and its manufacture |
| US4950143A (en) * | 1989-01-03 | 1990-08-21 | Continental Pet Technologies, Inc. | Injection mold manifold arrangement |
| JP2674185B2 (en) * | 1989-02-28 | 1997-11-12 | 三菱樹脂株式会社 | Multi-layer ring base |
| USRE35368E (en) | 1989-05-16 | 1996-10-29 | J. M. Huber Corporation | Endothermic blowing agents for surface migration of components in foamed products, compositions and applications |
| USRE35447E (en) | 1989-05-16 | 1997-02-11 | J. M. Huber Corporation | Endothermic blowing agents for strengthening weld lines in molded thermoplastic resins and products |
| US5009810A (en) | 1989-05-16 | 1991-04-23 | J. M. Huber Corporation | Endothermic blowing agents compositions and applications |
| US5009809A (en) | 1989-05-16 | 1991-04-23 | J. M. Huber Corporation | High temperature endothermic blowing agents compositions and applications |
| DE3936289C2 (en) * | 1989-11-01 | 1996-01-25 | Battenfeld Gmbh | Device for injection molding plastic objects containing cavities |
| JPH03272821A (en) * | 1990-02-05 | 1991-12-04 | Japan Steel Works Ltd:The | Injection head |
| US5040963A (en) * | 1990-04-24 | 1991-08-20 | Devtech Labs, Inc. | Apparatus for coinjection molding of preforms for multi-layer containers |
| US5221507A (en) * | 1990-04-24 | 1993-06-22 | Devtech Labs, Inc. | Process for coinjection molding of preforms for multi-layer containers |
| HU211099B (en) * | 1990-06-01 | 1995-10-30 | Mauser Werke Gmbh | Storing head for die-casting machine producing hollow plastic form pieces periodically |
| US5078589A (en) * | 1990-06-15 | 1992-01-07 | Osuna Diaz J M | Multicavity injection molding apparatus having precision adjustment and shut off of injection flow to individual mold cavities |
| DE4020819A1 (en) * | 1990-06-29 | 1990-11-08 | Bock Stefan Dipl Ing Fh | STORAGE HEAD FOR THE PRODUCTION OF SINGLE OR MULTILAYER HOSE-OVER-HOSE STRUCTURED PREFORMS FROM THERMOPLASTICS |
| US5078942A (en) * | 1990-08-16 | 1992-01-07 | Griffco Plastics, Inc. | Coextrusion method and apparatus |
| US5069612A (en) * | 1990-09-20 | 1991-12-03 | General Electric Corporation | Modular tubular extrusion head |
| US5223275A (en) * | 1990-10-12 | 1993-06-29 | Gellert Jobst U | Multi-cavity injection moulding system |
| CA2032294A1 (en) * | 1990-12-17 | 1992-06-18 | Jobst Ulrich Gellert | Thermal valve gated injection molding apparatus with melt distribution plate |
| US5143733A (en) * | 1991-04-19 | 1992-09-01 | Husky Injection Molding Systems Ltd. | Injection molding apparatus |
| JP3208803B2 (en) * | 1991-05-20 | 2001-09-17 | ソニー株式会社 | Article injection molding method, injection molding apparatus, mold used therefor, and cassette half for magnetic tape |
| US5200207A (en) * | 1991-06-10 | 1993-04-06 | Husky Injection Molding Systems Ltd. | Hot runner system for coinjection |
| US5149547A (en) * | 1991-06-12 | 1992-09-22 | Automotive Plastic Technologies, Inc. | Apparatus for multi-cavity injection molding |
| US5170011A (en) | 1991-09-25 | 1992-12-08 | Teleflex Incorporated | Hose assembly |
| US5328650A (en) | 1991-10-08 | 1994-07-12 | Owens Illinois Closure Inc. | Method of distributing pigments in compression molded products |
| US5316583A (en) * | 1991-11-06 | 1994-05-31 | Milliman James A | Cross-head die with improved flow distribution |
| DE4206318C2 (en) * | 1992-02-29 | 1994-06-16 | Otto Maenner | Multiple needle valve nozzle for injection molds |
| US5474723A (en) * | 1992-04-17 | 1995-12-12 | Horikoshi; Maki | Method of forming a shaped article of resin using cavity enlargement to induce foaming |
| CA2068543C (en) * | 1992-05-11 | 1999-11-09 | Jobst Ulrich Gellert | Coinjection molding apparatus having rotary axial actuating mechanism |
| EP0576925B1 (en) * | 1992-06-23 | 1997-08-20 | Battenfeld Kunststoffmaschinen Ges.m.b.H. | Injection unit for injection moulding machines |
| US5460771A (en) * | 1992-10-16 | 1995-10-24 | Itt Corporation | Process for producing corrugated multi-layer tubing having layers of differing plastic characteristics |
| US5383257A (en) * | 1993-04-05 | 1995-01-24 | American Cord & Webbing Co., Inc. | Co-injection molded buckle |
| JP3418639B2 (en) * | 1993-04-09 | 2003-06-23 | 株式会社新興セルビック | Injection molding equipment |
| DE4326326A1 (en) | 1993-08-05 | 1995-02-09 | Happich Gmbh Gebr | Plastic molding and method of manufacturing the same |
| NO178771C (en) | 1993-09-15 | 1996-05-29 | Polynor Partners As | Process for producing light cell plastic product with closed cells |
| IL110514A0 (en) | 1993-10-04 | 1994-10-21 | Eastman Chem Co | Concentrates for improving polyester compositions and a method for preparing such compositions |
| US5443378A (en) * | 1994-07-11 | 1995-08-22 | Ferromatik Milacron Maschinenbau Gmbh | Apparatus for the sandwich method of injection molding |
| US5650178A (en) * | 1994-11-23 | 1997-07-22 | Bemis Manufacturing Company | Co-injection manifold for injection molding |
| US5552105A (en) * | 1995-02-15 | 1996-09-03 | Owens-Brockway Plastic Products Inc. | Injection blow molding machine with stacked molds |
| US5556582A (en) * | 1995-02-17 | 1996-09-17 | Stanford University | Injection molding gate flow control |
| US5795166A (en) | 1995-02-23 | 1998-08-18 | Meixler; Lewis D. | Self contained child resistant electrical plug safety lock |
| US5531581A (en) * | 1995-03-27 | 1996-07-02 | Donnell, Jr.; Emerson B. | Ajustable injection molding apparatus |
| US5601773A (en) * | 1995-05-12 | 1997-02-11 | Cincinnati Milacron Inc. | Co-injection machine |
| US5599568A (en) * | 1995-08-10 | 1997-02-04 | Donnell, Jr.; Emerson B. | Adjustable injection molding apparatus for creating of products within a mold from fluid plastic material |
| US5696176A (en) | 1995-09-22 | 1997-12-09 | Eastman Chemical Company | Foamable polyester compositions having a low level of unreacted branching agent |
| DE19538160A1 (en) * | 1995-10-13 | 1997-04-17 | Hoechst Ag | Shaped structures made of a thermoplastic foam, process for its production and its use |
| US5595799A (en) * | 1995-12-14 | 1997-01-21 | Dtl Technology Limited Partnership | Coinjection molding of decorative preforms and containers produced from such preforms |
| US5661193A (en) | 1996-05-10 | 1997-08-26 | Eastman Chemical Company | Biodegradable foamable co-polyester compositions |
| US5783234A (en) | 1996-07-25 | 1998-07-21 | Husky Injection Molding Systems Ltd. | Hot runner valve gate for eliminating unidirectional molecular orientation and weld lines from solidified resin used for forming molded articles |
| US5989473A (en) | 1996-07-29 | 1999-11-23 | David G. Haverty | Manufacturing composite parts with integral porous components |
| US5916605A (en) * | 1996-09-27 | 1999-06-29 | Dynisco Hotrunners, Inc. | Valve actuated injection molding apparatus |
| DE19649621B4 (en) * | 1996-11-29 | 2007-08-02 | EWIKON Heißkanalsysteme GmbH & Co KG | Connection arrangement for melt channel sections in hot runners |
| US5862571A (en) | 1997-01-10 | 1999-01-26 | Hp Intellectual Corp. | Comfort grip handle and process |
| US6062840A (en) * | 1997-09-02 | 2000-05-16 | Dynisco Hotrunners, Inc. | Hot runner system for coinjection molding |
| US5972258A (en) * | 1997-10-20 | 1999-10-26 | Husky Injection Molding Systems Ltd. | Method of using a multiple gating nozzle |
| CA2219260C (en) | 1997-10-23 | 2006-12-05 | Mold-Masters Limited | Injection molding apparatus having inter-manifold melt transfer bushings |
| US5985188A (en) | 1998-06-09 | 1999-11-16 | Aero Components, Inc. | Method for manufacturing a chair having separate moldable parts |
| US6089468A (en) * | 1999-11-08 | 2000-07-18 | Husky Injection Molding Systems Ltd. | Nozzle tip with weld line eliminator |
-
2001
- 2001-11-30 US US09/997,766 patent/US6964748B2/en not_active Expired - Lifetime
- 2001-11-30 CA CA002364050A patent/CA2364050A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US20020079603A1 (en) | 2002-06-27 |
| US6964748B2 (en) | 2005-11-15 |
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