CA1093728A - Thermosetting compositions for injection molding - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A vulcanizable composition suitable for thermoset injection molding consisting essentially of about 35 to about 75 parts by weight of (A) an ethylene-vinyl acetate copolymer containing about 7 to about 55 weight percent of vinyl acetate based on the total weight of said copolymer about 65 to about 25 parts by weight of (B) a clay filler selected from the class consisting of an organosilane treated clay and an organo-polyester treated clay; he sum of (A) + (B) being about 100 parts by weight in the composition; about 1 to about 5 parts by weight based on the sum of (A) + (B) of (C) an organic peroxide crosslinking agent having a half-life at its stock temperature of greater than one hour; and 0 to about 5 parts by weight based on the sum of (A) + (B) of (D) of an organic crosslinking booster; wherein said components (A), (B), (C) and (D) are such that a crosslinked product obtained upon crosslinking an admixture containing only said components (A), (B), (C) and (D) in the same proportions as (A), (B), (C) and (D) are present in said vulcanizable composition, has a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the same temperature employed to crosslink said admixture. The in-vention is believed to represent the first thermosetting, injection moldable composition based on ethylene-vinyl acetate copolymers. It differs from prior art compositions primarily in that a specific copolymer containing specific amounts of comonomers polymerized therein are required, and that clay treated with silane or organopolyester is required.
Also, the peroxide must halve specific properties described above.

Description

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BACKGROUND OF THE INVENTION

This invention relates to vulcaniæable ethylene-vinyl aeetate compositions suitable for injection molding, a process for preparing cross-linked thermoset injection molded articles which employs said compositions> and to crosslinked thermoset articles of ma~ufacture prepared there-from.
The successful manufacture of thermoset 10 injec~ion molded articles requires the use of vulcaniz-able (crosslinkable) compositlons that will not only satisfy the perfonmance requirements of the final ar~iele product, but which will als~ meet the stringent requirements of thenmoset inj ection molding .
For instance, thermo~et injec~ion molding imposes specifie processing conditions on the wlcanizable composition such as stability in the machine barrel for long periods of time (i.e., the avoidance of premature crosslinking), rapid cure times in the heated mold, sufficient flow to fill complex par~s, low.~hrinka~e to avoid deform~tion when thick and thin sections are present and, very importantly, the thermoset molded product must ha~e a sufficient tensi~e streng~h a~ the mold tempera~ure to survive the:de-molding operation without tearing or dis~orting. Fox : these r~aæons, ormulations employed il~ the extrusion coating of a wire or able ~nd ormulations for th~rmoset injection molding may be widely different and are '7~ ~

usually not interchangeable for the two processes.
Heretofore, the thermoset injection molded articles have been mad~ for the most part from elastomeric materials such as ethylene propylene diene monomers. However, such thermoset EPDM
rubbers generally require long cure cycle times at high temperatures and normally require a surface treatment in order to be painted.
It has now been discovered that ~hermoset injection molded articles can be prepared from the vulcanizable (cros.slinkable) ethylene-vinyl acetate compositions of this invention which compositions not only require relatively low temperature short cure cycle times but in addition have good molding lati~udes, i.e. are stable in the machine barrel for long periods of time, and also result in thermoset products that have good low temperature impact resistance, - a good seoant modulus range, good paint adhesion, low shrinkage, high tem~erature ~tability and a tensile strength at the mold temperature of at least about 250 pounds per square inch allowing for an easy remo~al of the thermos ~ injection molded article from ~he hot mold during the demolding operation wi~hou~ ~earing or distorting said arti~le.
Thus, it is an okject of this invention to provide a wlcanizable e~hylene-vinyl acetate com~osition whlch is parti~ularly useful in the manufacture of thermoset injection molded articles. ~nother objec~

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of this invention is to provide a process for preparing thermoset injec~ion molded articles which comprises employing as the wl.canizable composition, the above mentioned novel composition of this invention. A further object of ~his invention is to provide an article of manufacture comprising the crosslinked thermoset product obtained upon injection molding and crosslinking said vulcanizable ethylene-vinyl acetate composition of ~his invention.
Other objects and advantages of this invention will become readily apparent from the following description and appended claims.
More specifically, one aspect of the instant invention may be described as a vulcanizable composition suitable for thermoset injection molding consisting essen ially of a~out 35 to about 75 parts by weight o (A) an ethylene-vinyl acetate copolymer containing about 7 to about 55 wei~ht percent of v~ l acetate based on the total weight of said copolymer; about 65 to 25 parts by weight of (B) a clay filler selected from the class consisting of an organosilane ~reated clay and an organopolyester trPated clay; the sum of ~A) + (B~
being about 100 parts by weight in the co~position;
about 1 to about 5 parts by weight based on the sum of (A~ + (B) of (C) an organic peroxide crosslinking agent having a half-life at its stock temperature of grea~Pr t~an one hour; and O to abou~ 5 par~s by weight based on the s~m of ~A) + (B) of (D) of an organic crosslinking boos~er; wherein said componen~s ~ .

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~A), ~B), (C) and (D) are such that a cro~slinked product obtained upon crosslinking an admixture containing only said components (A), (B), (C) and (D) in the s~me pro portion~ ~s (A), ~B)~ (C) and (D~ are present in ~aid vulcanizable composition, has a hot tensile strength o at least 250 pounds per square inch whe~ measured accord-ing to ASTM D412-64T at the same temperature employ~d to cro slink said admixture.

DESCRIPTION OF THE PREFERRED
10 l~MBO~IMENTS

The ethylene-vinyl acetate copolymersg and/or methods for thelr preparation 9 which can be employed in the vulcanizable c~mposltions of this invention are well known in the ar~. Said ethylene-vinyl acetate copolym0rs can contain from about 7 to abou~ 55~ prefer ably about 10 to about 35, weight percent of vinyl acetate based on the total weight of the copolymer. Moreover~
said ethyleIle-vinyl aeetate copolymers may possess any melt index so long as it does not adversely affect the hot tensile strength limitation defined herein above.
For instance9 crosslinked c~mpositions having a hot . te~sile ~trength 5f at least 250 pounds per square inch when measured acrording to ASTM D412-64T at the temperature at which they were crosslinked have been obtained with ethylene vinyl acetate copolymers having melt indexes ranging rom abou~ 0.4 to about 375~ The most preferred copolymer em~loyed in this invention is an ethylene~vinyl acetate eopolymer containing about 3 ~ ~

28 weight percent vinyl acetate. Of course, i~ is understood that if desired mixtures of different ethylene-vinyl acetate copolymers, i.e~ having different vinyl acetate contents and/or different melt index values can be employed in the vulcanizable compositions of this in~ention.
The term "clay" as used in this invention repxesents an lnert, water-insoluble, naturally occurr-ing sediment or sedimentary rock composed of one or 1~ more minerals and accessory sompounds. Usually the clay is rich in hydrated silicates of aluminum, iron, or magnesium or hydrated alumina or iron oxide. These silicates and related minerals exist predominantly in particles of colloidol or near colloidal size and they commonly develop plasticity when sufficiently pulverized and wetted. Examples of su~h clays include, but are not res~ricted to, glacial clays, kaolins, ball clays, fire clays, loess, adobe slip clay, ben~onite, fullers earth, bleaching clays, and high al~mina clays such as nodular 20 clays, bosley flint, bosley and diaspore clays, and bauxite elays. The clays can be crystalline as are those of the kaolin group, for example; kaolmite, dickite and anauxite;
of the montmorillonite group, for example, bentonite clays such as beidellite, nontromite, hectonite, saponite and sauconite; of the iIlite group; and 3f the attapulgite group; or noncrystalline or amorphous for example, allophane and evansite. Of course, it is understood ~hat such clays can be calcined ~v remo~re the water of hydration if desired. The particle size ~3~7~

D-~1051 of the clay used is no~ critical although clays having particle sizes ranging fr~m OL1 to 100~ and particularly 0.1 o L0~ are preferred.
It is critical that the clay filler be treated (i.e, substantially coated) with an organosilane or organopolyester compoundO Vulcanizable c3mpositions containing corresponding ~ntreated clay fillers have not been fou~d to provide a crosslinked thermoset product having a hot tensile ~trength of at least 250 pounds per 10 square inch as defined herein.
The organosilane compounds of the organosilane ~reated clay fillers employable in this inven~ion may be any conventional organounctional silane containing hydrolyzable ~roups such as those of the formula R~ a R~ S i~ 3 -a wherein R represents an unsaturated or~anic radical or a f~tctionally subs~itu~ed organic radical 9 R' represents a monovalen~ hydrocar~on radical, e.gO
20 phenyl and lo~er alkyl, preferably methyl" a has a value of 0 or 1, prefera~ly 0, and X r presents a hydrolyzable group. Illustrative of the more preferred unsaturated orga~ic radicals are olefiItic radicalsS eOg.
vinyl a allyl9 g~mma~methacryloxpropyl~ and the like.
Illustra~ive of ~he more preerred function~lly sub-stitu~ed or~sanlc radicals are amino su~sti~u~ed radicals ~
such as aminoalkyL radicals, e . g . beta~aminoeth~rl 9 gamma-amillQpropyl 5, N-beta (aminoe~hyl 3 ~g~a-aminoE~ropyl y ~nd the like, epoxy substituted radical~ sueh as beta~ ~3 ,4-epoxycyclohexyl ) ~ethyl, ga~na glycidoxypropyl, and the ~ike; and mercapto substituted xadicalsa 7~

D~-11051 e.g. mercaptoalkyl radicals such as beta-mercaptoethyl, gamma-mercapto-propyl and the like. Illustrative of ~he hydrolyzable groups represented by X are halide atoms, preferably chlorine; alkoxy radicals such as methoxy, ethoxy, 2-methoxyethoxy, and the likP; and acyloxy radicals such as acetoxy, and the lik~. Among the more pref~rred silane coupling agents that may be mentionPd are vinyltrichloro~ilane, vinyltriethoxysilane, vinyl-trimethoxysilane, vinyltris(2-metho~yethoxy) silane, gamma-methacryloxypî-opyltri~etho~ysilane, beta-~3,4-epoxycyclohexyl) ethyltrimethoxysilane, gamma-glycidoxypropyltrime~hoxysilane, vinyltriacetoxysilane, beta-mercaptoethyltriethoxysilane ga~ma-mercaptopropyl-trimethoxysilane, beta-aminoethyltriethoxysilane, gamma-aminopropyltriethoxysilane, ~-beta-(aminoethyl) gamma-aminopropyltrimetho~ysilane, and the like. The most preferred organo~ila~es are the vinyltrialkoxy silanes, esp~cially vinyltris(2-~ethoxyethoxy) silane.
The organopolyester compounds of the organo-polyester treated clay fillers employa~le in this invention may be any conventio~al organopolyester. Such con-ventional polyesters are the reaction products of polyfu~ctional organic carboxylic acids and/or their anhydrides with polyhydric alcohol~. Typical poly~
functional organic carboxylic acids are dicarboxylic aliphatic acids such as succinic J adipic, gebaclc, azelaic, glutaric, pimelic~ ~uberic, and the likc, and aromatic dicarboxylic acid~ such as phthalic acid, D3t7~

terephthalic acid, isophthalic acid, and the like.
Alternati~:~ely the anhydrides of such acids can be employed in producing ~he polyester. Typical poly-hydric alcohols ("polyols"~ are alkylene glycols such as glycerol, 1,2, 6~hexanetriol, ethylene glycol, trimethylol propane, trimethyolethane, pentaerythritol, .
propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, diethylene glycol, dipropylene glycol and the like.
The preferred organopolyes~ers are the un saturated polyesters such as the condensation products of an unsaturated dibasic acid, a saturated dibasic acid, and a glycol. The unsaturated in~ermediates axe commonly maleic anhydride, fumaric acid, and the like; the saturated acids are commonly phthalic anhydride, isophthalic acid, adipic acid, and the like;
while the glycols are commonly propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol and the like. Of course, i.t is understood that such commercial org~nopolyesters may con~ain if desired a crosslinking monomer such as styrene, vinyl toluene, methyl methacrylate, oC-methyl styrene, diallyl phthalate, and the like;
as well as inhibitors to retard crosslinking until the polyester is to be used such as hydroquinone, quinone, t-butyl catechol, and the like. The preferred commerical organopolyesters of the organopolyester treated clay fillers employed in this invention are Paraplex P43 (Rhom & Haas Co.~ and Selection * Trademark or Tradename ~ 7~ ~ D-11051 5003L (Pi~tsburgh Plate Glass Co.~ both which are believed to be polyester condensa~ion products o phthalic anhydride, maleic anhydride and 1,2-propane-diol (propylene glyco1) dispersed in a styrene monomer.
The particular treabment and manufacture of the organosilane treated clay fillers and organopolyester treated clay fillers employable ;n this invention i.s not critical and is well k~o~n in the art as ~een e.g. by U.S. Patent 3,080,256~ 3,290,165; 3~390.120;
3,425,9809 3~567~69~; and the like. Indeed any such trea~ed clay filler may be employed in this invention so long as it does not adversely affect the hot tensile strength limi~ation of the present inventlon as defined herein above. Illustrative examples of such eommercial treated elay fillers are Icecap KE';and I ecap';
OE ~Burgess Pigment Co.) both of which are vinyl-tris ~2-methoxyethoxy) silane treated calcined clays (aluminum-silicate) and Kaogan 7'`(Georgia Kaolin Co.) an unsaturated organopolyester treated kaolinite (alumin~-silicate) where it is believed that the organopolyester is the polyester condensation product of maleic anhydride, phthalic anhydride and 1,2 propandeiol dispersed in styrene. The preferred treated clay fillers employable in this invention are organosilane treated clay fillers.
Thus, any organosilane treated clay or organopolyester treated clay or mixtures thereof if desired can-be employed in this invention so long as the desired crosslinked product has a hot melt index of a~ lPast 250 pounds per square inch as defin~d herein.
l. Mar. 5 ~ 1965 ~ Bundy

2, Dec.g 1966 9 Iannicelli 30 June 25, 1968 Iannicelli 4c Feb. 4, 1969, Baum 5a Marc 2, 1971, Kovacs et al * Trademark or Tradename -r~ lo, .1 , ~-11051 The organic peroxide crosslinking agents employed in this invention include any peroxide cross-linking agent which has a half-life a~ the stock temperature of the vulcani~able composition employed of at least one hour. Of course, it is ~nderstood that the texm "stock temperature" as employed herein is that minimum temperature necessary to melt the vulcanizable composition employed, i.e. cause it to flow, so that it may be injected into the heated mold used in the injection molding process. Thus, the vulcanizable co~positions of this invention are stable for at least one hour against precrosslinking at their stock temperature. Illustrative exa~ples of such crossli~king agents are 1, 1-bis~t~butylperoxy)-3,

3,5-trimethyl eyclohexane, t-bu~ylperoxy isopropyl carbona~e~ t-butyl perQxy benzoate, dicumyl peroxide, ~,6d~'-bis ~t butylperoxy)diisopropyl benzene, 2,5-dimethyl-2, S~diCt-butylperoxy) he~a~e, 2,5-dimethyl-2, 5-di(t-butylperoxy) hexy~e-3, di-t butyl peroxide, and the like. ILlustrative examples of peroxide crosslinking agents which wer~ found not to satisfy the above defined stoek tempera~ure limi~a~ion are 2 J 4 dichlorobenzoyl peroxide and benzoyl peroxide. The most preferred crosslinking agent employed herein is 1, l-bis(~-butylperoxy~-3, 3~ 5-trimethyl cycLohexane since this specific crossli~ker has bcen fo~nd to provide the fastest cure cycle (i.e. less than abou~ ~hree minutes~
at the lowe~t mold ~cure) temperature (i.e. about 149C3 at which a cross~inked product of ~n admix~ure 3'7~

con~aining only above defined components (A), ~B), (D~ and said speciic crosslinker, in the same proportions as (A), (B), (Dj and said specific cross-linker ~re present in the vulcanizable composition having a ho~ tensile strength of at least 250 pounds per squa~e inch when measured according to ASTM ~412~64T
at said mold temperature can be obtained. Of course, mix~ures o two or more diferent organic peroxides can be employed if desired.
The orgEmic crosslinking ~ooster compo~nds and/or methods for ~heir prepara~ion which may if desired be employed in this invention are well known in the art.
Such booster compounds, are in general not an essent~al ingredient of the instant invention ln terms o providing for a crosslinked admixture having a hot tensile strength of at least 250 pounds per square lnch wen measured accord~ng to ASTM D412~4T at the mold temperature employed to crosslink the admixture as defined above9 but may, i desired be employed to increase the efficiLerlcy of the or-20 ganic perioxide crossl~king agent by helpi~g to provide a faster more comple~e cure wit:h ïess by-produc~s. Moreover.
~ while such is not generally ~ecessary ~o satlsfy ~he minimum hot tensile strength value o th thermoset crosslinked products of this invention, irl certain instarlces the use of a booster may be employed when it is desired to achieve thermoset cxosslinked products 1~ .

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having an even higher hot tensile strength. Illustrative examples of such organic crosslinking boostPr ccmpounds include various methacrylate monomers such as trimethylol-propane trimethacrylate, 1,3-butylene glycol dimethyl-acrylate, ethylene glycol dimethacrylate, tertaethylene glycol dimethacrylate and the like, as well as other poly~unctional monomers, such as triallyl cyanurate, and the like. The preferred organic crosslinking booster is trimethylolpropane trimethacrylate. Of course, 10 mixtures two or more diferent organic ~rosslinking boosters can be employed 9 if desired.
As pointed out above, the amount ratio of (A) ethylene-vinyl aceta~e to (B) silane and/or polyester treatPd clay filler in the vulcanizable compositions of this invention can range from about 35 to about 75, preferably about 40 to about 65, parts by weight of (A3 to about 65 to about 25, preferably about 60 to about 35 parts by weight of (B), the sum amount of ethylene-vinyl acetate plus silane and/or polyester treated clay filler, ((A) ~ (B)3 ln said compositions being 100 parts by weight, while th~ amount of organic peroxide crosslinker ~C) present in said compositions can range from about l to about 5 parts by weight or higher if desired per 100 parts by weight of the sum of (A) + (B) as defined above, and the amount o organic orosslinking booster compound ~ present ln said compositions can range from 0 to about 5 parts by weight or higher if desir d per 100 parts by weight of the su~ o~ (A) ~ (B) as d~ined above. The most preferred vulcanizable compositions of this invention contain about 60 parts by weight of ethylene-vinyl acetate, about 40 parts by weîght of a silane or polyester treated clay filler~
about 1.5 parts ~y weigh~ of an organic peroxide cross-linker, and which are either free from ~he presence of an organic crosslinking booster or contain about 2.S
parts by wei~ht of an organic crosslinking booster, sald c~mponents having been defined more fully above.
Of course, it is to be understood ~hat while the presence of additonal additives is not required in the compositions of this inventio~, if desired9 said c~mpositions m~y contain conventional additives in the conventional used quantities c~mmonly employed in vulcanizable c~mposi~ions suitable for thermoset in~ect;on mol~ing. Examples of such additives include, e.g~ age resistcrs, processing alds, stabilizers~
antioxidants 7 crosslinkin~ re~arders~ pigments, lubrican~s~
ultraviolet st~biliæers, antiblock agents and the like.
The total &mount of such ~ddi~ives when used normally ~motmting to no more than about 3 percent by weight ~ased on the ~otal weight of ~he w lcanlzable c~mposition.
~ The vulca~izable c~mpositions of this inve~tion can be prepared in any conventi3nal m~nner. For instance the components may be merely added in ~ny desired order ~nd milled until they are thoroughly and intimately mixed. Of cour~e when the organic peroxide 14.

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is present the milling should not be carried out at a temperature ~hich will cause pr~ma~ure crosslinking.
The vulcanizable c~mpositions of this in-vention are indeed uni`que. They have a stability at their stock temperature of a~ least about one hour.
Moreover ~hey have been found ~o provide ~hermose~
crossllnked products having a hot ten~ile ~trength of at least ~50 pounds3 and more preferab~y at least 400 pounds, per square inch when measured according to ASTM D412-64T at the t~mperature ~mployed to crosslink the composition. They have been found to be particularly suitable for preparing inJection molded products. For îns~ance said hot tensile strength l~mita~ion ofers an easy screening method for determin~ng which vulcan~z~
able c~mpositio~s will corre~pondingly provide for crosslinked thermoset injection molded products having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in formi~g said thermoset produc~s. In general ~he cro~slinked ~hermose~ in-jection molded products of this invention will normally have a higher ho~ tensile strength value as defined herein than that o~ the ~orresponding eompression molded crossllrlked admlxture derived from the same wleanizable composition~, The minim~ml hot tensile strer~gth vallle of at least ~50 pounds per square inch i~ considered herein ~o be tha~ minim~n vaïue required ~o provide for a crosslinked th2rmOSe1~ ectiL~ molded product ~ha~

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can be easily removed from the mold without tearing or distorting said molded product. In addition, said wlcanizable c~mpositions have been found to require short cure cycle t~es~ e.g. less than five minu~es~
to result in thenmoset lnjection molded products.
The vulcanizable compositions of this invention also have good flowability and good mold~ng latitudes as discussed aboveP Of course9 it is to be understood that not every possible c~mbination of c~mponents may resul~ in a crosslinked product having the same degree of beneflcial properties. However, the determinatlon of the more deslrable vulcanizable compositions of ~his invention is well within the knowledge of one ski11ed in the ar~ and can readily be determined by routine experL~entation as taught herein.
The general procedure and equipment employed in injection molding and cros~l~nking the vulcaniza~le eomposi~ions of this invention can correspond in general to any of the conventional procedures and equipment heretofore employed ln injection molding and crosslinking other thermoset vulcanizable c~mpositi~ns, such as EPDM
c~mpositio~s~ phenolic resin e~mposltions, and thP likeO
In addition 3 due to the ~nique stability against pre~
mature crossl~nking po~sessed by the wlcanizable c~m-posi~ions of ~his invention, said composi~io~s ~an5 if desiredg be also used in reeently developed wanm r~nner in~ection molding equipme~t such as that sho~n3 e.g.

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iO ~ ~ 7~ ~ D-11051 in U.S. Patents 3,591,897 and 3j959,433. Such warm r~nner injection molding equipment contains a ~unner that carries the vulcanizable composition to the ho~ mold cavity, said runner being insulated from the hot mold and maintained at a temperature below that of the hot mold and insufficient to cause crosslinking of the vulcanizable composition during that period of ~ime that said vul-canizable composition is in the runner during a normal molding operation. In older more conventional systems the runner is not insulated from the hot mold cavi~y but main-tained at the same temperature of the hot mold thus causing crosslinking of the wlcanizable composition in the runner.
In contrast in the warm runner molding operation the w lcanizable composition stays softened and flowable in the runner of the injection molding apparatus, but does not cure in the runner under normal operations. Rather it it injected into the hot mold cavity by the next charge of wlcanizable composition. Accordingly, the amount of crosslinked thex~oset scrap generated by ~ the warm ru~ner molding system is far less than that generated by the older conventional system since the vulcanizable composition in the warm runner is not lost (i.e. crosslinked~.
In general the injection molded method of preparing the crosslinked ~hermoset articles of manufacture of this invention involves hea~ing ~he vulcanizable c~mposi~ion of this invention in an injection barrel to a stock temperature of about 100C. to about 120C.
preferably abou~ 105C~, ~o melt ~i.e. sof~en it to a state of flow ) the vulcanizable composition. The flowable 1. July 13, 19719 Perras 2. May 25, 1976, ~auers 17.
1~ ~

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softened wlcanizable composition i5 then forced (lnjected) into the preheated mold of the injection molding apparatus by a ram or screw mea~s, said mold having been preheated to a ~emperature sufficien~ to crosslink the vulcanizable composition within about five minutes, more pre~erably in abou~ three minutes, and said compositlon mainta~ed therein until crossllnked. The desired thermoset cross-1 inked molded product may then be demolde~ in any con-ventional ma~ner such as e.g. by being mechanically p~mched out9 air-ej~c-ted or more sLmply~ merely pulled out by hand. The preheated mold t~mperature will of course depend upon the particular w lcanizable c~mposition employed and in general may range rom about 138C.j more pre~erably frcm about 149C up to about 204C or higher if desired. When warm runner in~ection molding equipment is ~mployed it is preferred to maintain the t~mperature of the runner at approx~mately the stock ~mpera~ure of ~he ~ulcanizable composition, eOg. about 100C to about 120C.) preferably about 105C.
Thus, another aspect of this invent~on relates to a process for preparing a crosslinked thermoset injection molded pro~uct having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412~64T at the mold temperature ~mployed in said process~ which process comprises in~ecting a w lcanizable ethylene vinyl acetate com-positio~ vf this inven~ion into a preheated mold~
said mold having been prehea~ed ~o a k~mpera~ure sufficient to crossllnk said vulcaniza~l~ composition within five minu~es~ cros~linking ~aid composition 18.

~3t7~3 in said ~old, and recovering the thermoset injected molded produet by removing it.from said mold. The vulcanizable composi~ions and process conditions ~s well as their preferred embodiments have already been ~iven above. The term "crosslinked" as used herein means tha~ the product is permanently and irreversably fused into the shape or form which was taken during the molding steps. This is in contrast to a thermoplastic article which can be refo~med by simply heating ~he article to a temperature above the crystalline melting point or glass-transition temperature of the resin..
Accordingly, yet another aspect of thi~
invention may ~e described as an article of manufac~ure comprising a crossli~ked thermoset product obtained upon injection molding a~d erosslinking a vulcanizable composition of this invention, said crosslinked product having a hot tensile strength of at least 250 pound~
per square inch, more preferably at least about 400 pounds per square inch, when measured at the mold ~emperature aecording ~o ASTM D41~4T employed to effect said erosslinking.
The gPneral procedures or preparing said articles of manufacture of this invention are the same as dis-closed herein above. Of course, ~t is unde~stood that said articles o manufacture can take any shape or form desired such being merel~ dependent upon ~he type o mold us d ~nd product desired.

~ 9.

The crossiinked thermoset product article.s of manufacture of this invention are indeed unique în that they have good low temperature impact resistance, a good secant modulus range, good paint adhesion, low shrinkage, good tensile strength and elongation properties, high ~emperature stability, good 1e~ life, good chemioal and stress crack resistance~ and the like. Moreover, due to their excellent hot tensîle strength crosslînked - j thermoset products of this in~ention have been found to be generally easily removable from the hot mold without tearing or distorting the product.
The crosslinked thermoset articles of manufacture of this invention have a wide range of utîlity and may be used in the same manner as any number of flexible structural and cosmetic applications heretofore ~ainly restricted to the use of conventional elastomer (e.g.
EPDM) type injection molded arti.cles. For in tanee, they have many uses in the automotive and applicance industries as well as in the areas of sporting goods and recreation. For example, they ean b~ employed as automotive sight shields, gaskets, rub stripes, flex fenders, engine shrouds, bumper guards, moldings, wheel coverings~ hoses, swim fins, scuba e.quipment, 20.

handle bar covers, as well as for any oth r number of uses that require structural integrity of the article at temperatures above its normal melting point.
The following ex~mples are illustrative of the present inven~ion and are not ~o be ~egarded as limitative. I~ is to be understood that all par~s, percentages and proportions referred to herein and in the appended claims are by weigh~ unl~ss otherwise indicated. Mor~over in the following examples the hot ~ensile s~reng~h values at the various cure temp-eratures employed in crosslinking the vulcaniæable c~mpositions were all measured according ~o ASTM
D-412-64T published in the 1975 Boo~ of the American Society for Test;ng and Materials, ~3~

-Four vulcanizable ethylene vinyl acetate compositions were prepared having the following formulations:

_ABLE I
(Pa.rts by Wei~ht) Components Example 1 Example 2 Example 3 E~
`EVA 60 60 60 60 **Filler 40 4Q 40 40 +

Organic Peroxide 1.5 1.5 1.5 1.5 Crosslinking Booster - 1.0 2.0 5.
*

Ethylene (72V,~D)/Vinyl Acetate (28%) Copolymer, Melt Index 20 *~,.
Vinyltris(2-methoxyetho~y)silane treated calcined clay (Icecap KE;* Burgess Pigme.nt Co.) 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane ~Lupersol 231;* Penwalt Corp.) Trimethylol propane trimethacrylate ~Chemlink 30;* Ware Chem. Corp.~
Each composi.tion was formed and compression molded in the same manner at about 260F. into a square plaque (about 0.125 inches thick). Each plaque was then cured Scrosslinked) in the same mann~r in the mold by raising the temperature to about 280-300F and maintaining *Trademark or Tradename 22.

3~

thP plaque at said temperature under pressure (about 3000 psi ram force~ for about 15 minutes.
Various physical prop2rty tests were th~n conducted on the crosslinked molded plaques made from each composition and the results of said tests are given in TABLE II below.

TABLE II

Physical Propert es ~ Exa~ e~
*SMOE (psi) 8100 8730 9350 11000 Tensile Strength at R.T. (psi) ?240 2360 2710 2690 Hot Tensil~
Strength at 300F. ~psi) 371 394 457 40g Elongation at R.T. (%) 293 277 240 170 Elongation at 300F.
(~/O) 203 1~3 1~7 83 *

Secant Modulus of Elasticity -The above data demonstrates the high hot tensile ~trength of th~ crosslinked products obtained rom the vulcanizable compositions o this invention ~nd the effect obtained in varying the amount o crosslinking boo~ter.

~XAMPL~S 5 TO l9 A ~eries o~ vulcanizable ethylene-vinyl acetate compositions were prepared wherein the 2~

3'~

weight percent of vinyl acetate in the ethylene-vinyl acetate copolymer employed was varied as was the melt index of said copolymers. The ~sic formulation of each composition was as follows.

FORMULATION

mponent Parts by Wei~t *EVA 60 ~*Filler 40 Organic Peroxide 1.5 Crosslin~ing Booster 2.5 *Ethylene-vinyl acetate copolymer (varied as shown in TABLE III below) ~*Icecap KE (Same as defined in TABLE I) Lupersol 231 (Same as defined in TABLE I) Chemlink 3C (Same as defined in TABLE I) Each composition was formed an~ comprcssion molded in the sa~ manner at about 105C into a square plaque (about 0.125 inches thick). E~ch plaque was then cured (crosslinked) in the same manner in the mold by raising the temperature to about 300F. and maintaining the plaque at said temperature under pressure (about ~000 psi ram force) for about 15 minutes~.
Various physical property tests wer~ then conducted on the crosslinked molded plaques made from each composition and the results of said tests are given în TABLE III below.
* Trademark or Tradename 24.

, ' ~ ' `.

7Z~3 o $ o ~r~ I~ I_ I~
o ;o c _ o -.., ~
bOO
O ~ ~ O C~ O O s~ 1-- 0 1~
O ~ ~ O ~ C~ 0 ~3 ~ ~ O ~n o o a~ ~
rd_ .,~ .,, ~,~ tQ
~ ~ b~ P
~D O 0~ r~ ~ 1_ ~o u~
o J~ ~ W r~ ~D O ~ C~ O ~ 0 00 ,~, -E~
~o _ d P ~ o o ~ ~ ~ ~ o ~ ~ o ~ ~ ~ r~ ~ ~ 0 o ~ ~n ,~ o~ oo u a ' .,, ~ ,1 o o c~ o o 9 o c) o o o ~ o o d 1~ o c~ . "3 o ~ ~ ~ 1`

~ ~: o o u~ o o ~ u~ o O a.~ ~ O
~ ~ ~~ C~l ~ ~ ~ u~ Ul ~1 ~ In ~1 ~ O ~O
C~
~ ~
u~ . ~ ~ cr~ ~ ~ a~ ~ c~ o J ~ C`l C~- C~ ~ ~ P~ C`J ~ C~l TSOII~

~3'7~

The above data demons~rates the high hot tensile strength of the crosslinked products obtained from the vulcanizable compositions of this invention and the effect obtained in varying the amo~mt of vinyl acetate in the copolymer and the melt index of the copolymer. The low test results at 300F for Example 13 are believed to be due ~o an error in testing.

Five vulcanizc~ble ethylene-vinyl acetate comp-ositions were prepared having the :Eollowing formulations.
TABLE IV
(Parts by Weight) E~le E~ple Examp'le E~le E~le Components 20 21 _ 22 23 _ 24 ' *EVA 60 60 60 60 60 *'~"Filler A 40 40 - - -'~*`~Filler B - - 40 ****Filler C - - - 40 40 Organic Peroxide 1.0 1.0 1.0 1.0 1.0 Cross-linking Booster - 2.5 2.5 - 2.5 ~Ethylene (72%)/Vinyl Acetate ~28%~ Copolymer Melt Index 20 **An ~mtreated alkaline talc filler (magnesium silicate) (Mistron Vapor;*Cyprus Mines, United Sierra Div.) **~;An untreated calcined clay (Icecap K;*Burgess Pigment Co.) which is the same as Icecap KE,*bu~ without being organo-silane treated.
***~Vinyltris(2-methoxye~hoxy)silane treated calcined clay (Icecap OE-* Burgess Pigment Co.) which is -th~ same as Icecap KE,* except for being smaller in par~icle size.
+

Lupersol 231-~ (Same as defined in TABLE I) ~ .~
Chemlink 30 (Same as defined in TABLE I) *Trademark or Tradename 26.

Each composition was formed and compression molded in the same manner at about 210 F . into a square plaque . Eaoh plaque was then cured (erosslinked) in the same manner in the mold by raising the temperature to about 300F. and mairl~aln ing the plague at said temperaturc urlder pressure (about 3000 psi ram force) for about fiteen minutes.

TQ~BL, V

Physical Exam- Exam- Exam- Exam- Exam-~s ~;MOE (psi) 13, 200 15, 8û0 - 7, 970 9, 750 Tensil e Strength at R.T. (psi~ 1,190 1,260 - 260 361 Elong-ation at R. T . (%) 217 230 293 190 Hot Tensile Failed Failed at 300F. in Con- 18 in Con 260 361 (psi) dition~ dition~
2~ ing ing Elong- Failed ation at in Con- 140 - 320 113 300F~ (%) di~ion ing The vulcaniæable composition of Examples 20 and 22 ailed to crosslink at 300F and melted into a flowable state. Attempts to crosslink the compositlon o E~ample 22 at temperatures up to 360QF al~o failed.
~ le above data demonstrates that w lcanizable compositions (E~amples 20-22) outside the scope of this invention having untreated clay fillers falled to provide thermoset crosslinked p~oducts having high hot tensile strengths as provided for by the vuloanizable compositions of this invention (Ex~mples 23 nd 24).

27.

? J ~

EX~MPLES 25 TO 27 Three vulcanizable composition were prepared wherein the organic perioxide crosslinker was varied.
The basic formulation of each composition was as follows.

FORMULATION

Component Parts by Wei~t *EVA 60 ~';Filler 40 Organic Peroxide Varied Crosslinking Booster 2.5 *Ethylene (72%)/Vinyl Acetate (28%) Copolymer, Melt Index 20 **Icecap KE* (Same as defined in TABLE I) Varied as shown in TABLE VI below.
*
Chemlink 30 (same as defined in TABLE I) The organic peroxide employed in each comp-osition was used in different amounts to achieve a con-centration of 0.005 moles of p~roxide per 100 parts of resin (i.e. EVA copolymer and filler), so that the same molar concentration of peroxide crosslinker was employed for each composition.
Each composition was formed and compression molded in the same manner into a square plaque. Each plaque was then cured (crosslinked) in the mold by raising the temperature to that ~emperature where the ~alf-life of the particular organic pProxide employed in benzene is *Trademark or Tradename 28.

about one and one-half minutes and maintaining the plaque at said temperature for about 15 minutes.
The particular curing temperature employed for each composition is given in TABLE VI below, as are various physical properties obtained for each crosslinked molded plaque made from each c~mposition.

29.

n O X

~3 1 ~ n ~d O
t ,5~~ ~ ~-C:Y~ ~ ~q r ~ r~ o P~
(D I C~' O . ~ 'n ~ X. E.
o ~ ~ X
- r~ ~ ~D

O . . .
, ~ r~
_~ . ~
. o IJ
r~ IJ- X~
~-l-- o ;:~ ~
~-tt O ~q o r~
_, .
r~
N 1--1~1 ' oco ~ ~ ~
rd .
. .

p~
~n _J ~ ~ r~ r~
t o o o ~ lJ-~30q ~ e~
. ~D ~
~ c ~ p~
~ ~i ~ r~
o ~ lJ- o ~D ~ ~: ~ O
co ~ ~ ~ ~ ~t r~
n tt ~
ft a~ ~ ~ ~3 P~
O O ~ ~D rt 1~
~ p, (D r1 30 o =~

3~

The above data demonstrates that thermoset cross-linked products having high tensile strengths are also obtained when other organic peroxides are used.

A series of w lcanizable ethylene-vinyl acetate compositions were prepared using different silane treated clay fillers in different amo~mts. The formulations of said compositions are given in TABLE VII below.
TABLE VII
(Parts by W _ ~ht) E~le E~le E~le E~le Exa~ple Ex ~ le Co~p~nents 28 29 30 31 32 33 __ _ _ ~'~VA 90 75 60 90 75 60 ~i.ller A 10 25 40 - - -Filler B - - - 10 25 40 Organic Peroxide 2.5 2.5 2.5 2.5 2.5 2.5 *Ethylene (72V/O)/Vinyl Acetate (28V/o) Copolymer, Melt Index 20 ~ ~-beta~aminoethyl)-gamma-aminopropyl-trimethoxysilane treated hydrated alum~num silic~te ~ulok 321*; J.M. Huber Co.) ~Icecap KE* (aame.as defined in IABLE I) Lupersol* 231 (same as def~ned in IABLE I) Each composition was formed and compression molded in the same manner at about 105C. into a squaxe plaque (about 0.125 inches thick). Each plaque was then cured (crossli~ked) in the same manner in the mold by raising the temperature to about 300F and maintaining ~Trademark or Tradename 1 ~ ~ 3 7~ 8 D-11051 the plaque at said temperature under pressure (abou~ 3000 psi ram force) for about 15 minutes.
Various physical property tests were then con-ducted on the crosslinked molded plaques made from each composition and the results of said tests are given in TABLE VIII below.
TABLE VIII
+

Physical Exam- Exam- Exam- Exam- Exam- Exam-~E~ ies ple 28 ple 29 ple 30 ple 31 ple 32 ple 33 SMOE (psi) 3530 4600 7220 3620 5500 8250 Tensile Strength at R.T.
(psi) 1740 19~0 1840 18~0 1730 2400 Elongation at R.T. ~/O)~ 477 477 363 443 353 220 Hot Tensile Strength at 300F.(psi) 147 209 281 147 180 390 Elongation at 300F~/o) 160 140 100 123 157 113 The given values of SMOE all represent an average value of five runs for each Example. The given Tensile Strength and Elongation values both at R.T. (room temperature) and at 300F all represent an average value of three runs for each Example.

The above data demonstrates the effect in employing different amount ratios of ethylene-vinyl acetate copolymer to ~reated clay filler in obtaining thermoset crosslinked products.
EXAMPLE~ 34 TO 37 Four vulcanizable ethylene-vinyl acetate composi-tions were prepared having the fol1owing formulations given in TABLE IX below.

~3~

TABLE IX
(Parts by Wei~ht) Example Example Example Examp].e _mponents _4 _ 35 _ _36 37 ~EVA 60 40 40 40 **Filler A 40 60 60 ***Filler B - - - 60 Organic Peroxide 1.5 1.5 1.5 1.5 Cross-linking Booster 2.5 2.5 2.5 2.5 *Ethylene (60%~/vinyl acetate (40%) copolymer; Melt Index 51.5 **Icecap KE'~ (same as defined in TABLE Ij **~b~An unsaturated polyester treated Kaolinite filler (Kaogan 7, Georgia Kaolin Co.3. The polyester is believed to be the condensation product of maleic anhydride, phthalic anhydride and 1,2 propanediol dispersed in styrene.

Lupersol 231* (same as deflned in TABLE I) *
Chemlink 30 (same as defined in TABLE I) Each composition was formed and compression molded in the same manner at about 105C into a square plaque (about 0.125 inches thick). Each plaque was then cured ~crosslinked) 1n the same manner in the mold by raising the temperature to about 300F. and maintaining the plaque at said temperature under pressure (about 3000 psi ram force) or about 15 minutes.

XTrademark or Tradename ~3~

Various physical property tests were then conducted on the crosslinked molded plaques made from ea~h compvsition and the results of said tests are given in TABLE X below.

TABLE X

Physical Example Example Example Example Proper~ies 34 35 36 37 SMOE (psi) 1480 4~0 Tensile Strength at ~.T.(psi) 1640 2363 2130 1160 Elongatio~
at R.T~%~ 323 140 142 188 Hot TPnsile Strength at 300~F. (psi) 800 1510+ 549 516 Elongation at 300F.(%) 133 80 38 50 .

~These values appear to be hlgh. Example 36 w~ich is a duplicate of Example 35 is believed to give the more correct hot tensile strength value.

The above d~te demonstrates that high tensile strength thermoset rrosslinked products were obtained - with both a silane and a polyest~r treat~d elay filler~

s ~ O 41 Four ~7ulcanizal~1e composi~ions were prepared wherein the org~aic peroxide crosslinkcr was varied. The basic formulations of each cvmpositior~s are given in ~ABL~: XI below.

3~ 0 D~11051 TABL~ XI

Example Example Example Example Components 38 39 40 41 _ *-,~
Fi.ller 40 40 40 40 Organic Peroxide A 1.0 1.0 - -~ .
Organic Peroxide B ~ - 1.2 1.2 l l l Cross-linking Booster - 2.5 - 2.5 *Ethylene (72%)/Vinyl Acetate (23~/o) Copolymer; Melt Index 20 **Icecap KEX (Same as defined in TABLE I) 2~ +
t-butyl perbenzoate ~ .
t-butyl isopropylmonoperoxycarbamate (75% in mineral spirits) Chemlink 30* (Same as defined in TABLE I) The organic peroxide employed in each comp-osition was used ln diferent amounts to achieve a concen-tration of 0.005 moles of peroxide per 100 parts of resin (i.e. EVA copolymer and filler), so that the same molar concentration o p~roxide crosslinker was employed for each composition.
Each composition was formed and compression molded in the same manner into a square plaque. Each plaque was then cured (crosslinked) in the mold by raising the temperature to that temperature where the half-life of the particular organic peroxide employed in *Trademark or Tradename '7~
D-llOSl benzene is about one-half minute ~nd maintaining the plaque at said temperature for about 15 minutes. The particular curing temperature employed for each composition is given in TABLE XII below, as are the ~arious physical proper~y results obtained for each crosslinked molded plaque made from each composition.

36.

L~

h C~
~d bO
~r~
~1 ~ ~ O ~ c:~
_. cr~ oo ~ ,~

~r~
bO~rl a~
U~
Q~
~q E~ ~
U~ ~ oo O ~ ~ U~ C~ 1~7 ~ ~ ~d u ~
~3 .,~_~
b~
O i~
~I O ~D
~ C~

o4 JJ ~
V~--r~
~ ~ ~ C~ O C:
O ~ U~ Ln ~

~d 5~ ~
o o o O O
~E~

~.1 X O o~ o~ O --1 Z; ~ ~ `* ~
_ 3i~

I SOTI -C[

The above data demonstrates that various organic peroxides can be used to obtain thermoset crosslinked products having high hot tensile strengths. The or~anic peroxide of Example 41 is apparently not compatible with the crosslinking booster employed.

EXAMPLES ~.2 TO 56 A series of crosslinked thermoset injection molded ethylene-vinyl acetate products were prepared by inJection molding and crosslinking a ~llcanizable ethylene-vinyl ac~tate composition consisting of the following formulation at various cure temperatures using various cure times.

FORMULATION
-Gomponent Parts by We~
*EVA 50 **Filler 40 +

Organic Peroxide 1.5 Crosslinking Booster 2.5 ~Ethylene (72%)/vinyl acetate (28%); Melt Index 20 *~Icecap K~ (same as defined in TABLE I) Lupersol 231 (same as defined in TABLE I) * .
Ch~mlink 30 (same as defined in ~ABLE X) Each wlcanizable composition was injection molded and cur~d in the same manner using a Model 175, New Bri~ain thermoset injection molding machine having an ASTM Family Mold consisting of five mold cavities (a~ an 8 inch long, 0.125 inch thick tensile bar (dog bone~, (b) a 0.250 inch Trad2mark or Tradename 38.
.~

thick flex bar, (c) a 0.5 inch thick Izod impac~ bar, (d) a 0.125 inch ~hick, four inch disk, and (e) a 0.125 inch thick, two inch disk.
The conditions used for the injection molding procedure were as follows.

T~BLE XIII

Barrel T~æ ratures ~one 1 125F (indicated) Zone 2 150F (indicated) Nozzel Temperature 185-190F ~indicated) Stock Temperature 205F (measured) Screw Speed 52 RPM
Screw Travel 4-3/4 inches Plasticizing Pressure 25 psig. ~390 p5i~
Injection Pressure 800 psig. (12,350 psi.~
Holding Pressure 800 psig . ~12, 350 psi . ) Plasticizing Time 60 seconds Inj ection Time 12 seconds To~al Cure Cycle Time Varied (up ~o 3 minutes3 Mold Temper~ture Varied (300F ts:~ 360F~

Various cure temperatures and cure times were e.mployed to determi~e their influence on the physical properties of the crosslinked produ ts and to determine th~ shortest cure times required to achieve various optimum properties o the erosslinked products. The various cure ~emperatur~s and cure times are giveII in T~BLE XIV bel~w as are various physi~al properties for the crossllnked thermos~
injection molded produc~s obtainedO

39.

~L0~Z~ D-11051 i~ ~ ~ c~ o r~ o~ i~ ~ ~ ~
I ..... o ~ ~ ~
o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ W C~l N E~ JJ
t-l H Cd $ ~
~d ~ u~ o ~ u~ I~ r~ ~ o ~ u~ c~ O 1~ O
X" ~

.
,~

Q~
x ~ ~

a~
U

Oq ~ ~00 ~ ~ O 0 00 S~ O ~ O
o ~ . ~ ~ ~ _~ c~ Q ~ t~ r` o h ~ 4 h ~ ~ ~ 14 h h t4 s~ ~ ~ ~ ~ ~ ~ o ~ o e, oC ~ Co OC~ ~, 0~ 0 :~ ~ ~ O o ~ e~l c~l c~
: _ ~

V E~ :~ u~
. ~ ~

: :

~3 !

The thermoset crosslinked product samples of Examples 43,44,47,48 and 51 to 56 all exhibited very good tear strength and were easily removed from the mold wi~hout any tearing of the samples. The eJector pins indented the Izod bar of Example 52 and damaged the Izod bar of Example 53. In Examples 52 to 56 the mold cavities of the apparatus were sprayed with Teflon (E.I. DuPont de Nemours and Co.) prîor to injection of the vulcanizable composition. The thermoset crosslinked product samples of Examples 42,45,46, 43 10 and ~0 all exhibited poor mold release.
The above data demons~rates that ~he best tensile properties for the 0.125 inch thick tensile bar at the mold temperature result when the samples are cured at about 45 seconds to about one minute at about 300F to 320F. Higher cure temperatures result in poorer tensile stre.ngth measured at that cure temperature. The Izod împact values at -20F
show that thicker samples (0.5 inches thick) need to be cured for approximately three minutes at about 320F to reach optimum impact strength.

~ .
The vulcanizable compositions of Exam~les 38, 39 and 41, hereinafter referred to as Resins A, B and C respectively were employed to prepared crosslinked thermoset injection molded prod~cts by the same procedure and apparatus as des-cribed in and for Examples 42 to 56 above. The cure ~ime and cure te~perature employed as well as the physical properties of the crosslinked sample products are given in TABLE XV below.

* Trademar~ or Tradename fOL` poly(tetra-fluoroethylene) 41.

'72~

C~
I I C`J. O
N ~ ~ C~

~ O ~ O
F~ g P I ~ ~1:) ~ ~ I
0~ ~

~L

~D ~ t-u~
~ a~

E~ ~ . ~ r~
E~ I
~ ~ ~1 bO ~

~

a~ ~ '~ c:~ v ~ o ~D ~ U~
~ h ~ ~ ~ co r~l I
~1 ~1 j ~ h ii l ~4 14 E~ oo oo ~ ~ ~ ~

~3 ~

~J ~
;~
a~
r~ o .~ e~
Z; ~ ~ ~ ~ ~ ~
.

42 .
!

~ D-11051 The thenmoset crosslinked product samples ~f Examples 59 and 61 both exhibited very good tear strength and were easily removed from the mold without tearing.
The thermoset product samples of Examples 57~ 58 and 60 exhibited poor mold release due to inadequate cur;ng of ~he vulcanizable compositions. The thermoset products of Example 62 exhibited good mold release (the mold having been presprayed with Teflonl)e~en ~hough a deliberately insufficient cure time was employed.
The above data demonstra~es that the best results were obtained when the wlcanizable compositlons were cured for about three minutes at about 338F.

EX~MPLE 63 The crosslinked thermoset injection molded products (i.e. the 0.12$ inch thick, four inch disks) of Examples 42 to 56 and 58 to 61 above were tested for paint adhesion according to the ~ollowing procedure.
Prior to painting the crosslinked injection molded samples of said Examples 42, 44 to 46, 49 to 51, 55 and 56 and suraces of said samples were first cleaned wi.th dichloro-me~hane to remove any surface grime deposited during handling~
The crosslinked injection mol~ed samples of said Examples 43, 47, 48, 52 to 54 and 58 to 61 were used as is and were tested without cleaning their surfaces~
Each sample was then top coated in the same manner wi~h~~uratha~e 100 (Pittsburgh Plate ~lass Co~), and elastomeric automotive paint. After drying for several minutes at room temperature, each coated sample was placed in an 1. Trademark or Tradename for poly(tetra~luoroethylene) 2. Trademar~ or Tradename for an elastomeric enamel palnt con~aining thermosetting po~yurethane, alcohol and ketone~

, ..,~
.:.,-~

~3~

aven and the paint cured at 107C. (250F.) for 30 minutes.
The painted sarnples were then s~ored a~ room ternperature for thrPe days and then tested using the automotive "scotch" test. This test ~ olve.s scorlng the sample into ten grids ~crosshatch patte~n) and placing a strip of Scotch 600 t~pe over the ~cored area. The tape is rubbed to give m~ximum contact between the tape and the sæmple.
The tape is then quickly pulled from the sample and t:he grids r~moved with the tape are counted and expressed as percen~ paint loss.
The paînted s~mples of Examples 42 and 43 exhibited a 1C~-lo and 50% paint loss, respectively, while all the other painted samples of the remaining ExampLes exhiblted a zero percent paint los s O
Thi~ example demonstrates ~he excellent paint adhe~ion of ~he crosslinlced the~moset lnjection molded products of this invention.

E:XAMP1E 64 A vulcanizable ethylene-vinyl acetate composition having the ormulation ~ L~
* EVA ~
** F:Lller 40 Org~nio Peroxide 1.5 ~ Crosslinking Booster 2.5 * Ethyl ne 572%)/Vinyl Acet te (28%)~ Melt Index 23 ** Icecap KE` (Same as defined in Table I) Lllper~ol 23~ (Same as defined in Table I) Chemllnk 30 (Same as defined in Table I) *Trademar~ or Tr~dename 44, ~' ,.

~-11051.

was injection molded and crosslinked in a four ashtray ca~ity warm rul~er injection molding apparatus. The cure temperature was about 300F., ~he cure cycle time about 3 minutes and the temper~ture of the runner was maintained at about 195C. to about 205C. the same as the stock temperature of the plasticized ~omposltion in ~he barrel.
The crosslinked thermoset injection molded products pro-duced were easily remo~ed from the ash~ray molds without ~earing. ~he ~peration was run continuously for eigh~
hours w~thout any undesirable crosslinking of the w Lcan-izable composition in the runner of the apparatus.

___ A vulcanizable ethylene-vinyl acetate composi~ion having the formulation ~ t P ~ Y~ kE

* EVA 60 ** Filler 40 Organic Peroxide 1.5 * Ethylene ~7Z%)/Vinyl Ac~tate (28%); Melt I~dex 20 ~ Icecap KE (Same as defined in Table I) + Lupers~l 23~ (Same as defined in Table I) was ~njection molded and crossli~ked in~o thermoset ~njection moLde~ products using ~he same proeedure and apparatus as descr;bed in and for Examples 42 ~o 56 abovç.
The mold cure ternperatur~ employed was about 300 F . while * Trademark or Tradename .

'7`~

th~ cure cycle t~e wa~ about 3 min~te~. The cross1inked ~ample products were all easily remored from the mold without earing and the phy~ical properties o:f ~he produc~s obtained are gi~en in ~BLE XYI belc~wO

'r~BLE XVI
~b~L~
Tensîle Streng~h a~ R. T. (p~i) 2660 Elongation at R. T. (%) ) 147 Hot Tens ile S treng~
a~ 300 F . ~p~l~ 3~0 Elongation at 300 F . (%) SMOE ~psi) 8950 me abo~7~ da~a d~mons~rates ~kat high hot enæile strength for ~he ~hermc~set cros&l~nkad ~ct:~on molded produc~ ma~ be o~tained in ~he a~e~ce of a cro~linlciMg lboos . er.
Various modi:fications and lvariati~ns of this inventi~ will be obvi~us to a wDrke* skilled in the art and it is to ~e underst~d that such mDdifications and variations are t~ be inclllded within ~he purview ~f ~his applicati~n and the spirit and SCDpe o the appended cla~ms.

~6 .

Claims (34)

WHAT IS CLAIMED IS:

1. A vulcanizable composition suitable for thermoset injection molding consisting essentially of about 35 to about 75 parts by weight of (A) an ethylene vinyl acetate copolymer containing about 7 to about 55 weight percent of vinyl acetate based on the total weight of said copolymer; about 65 to about 25 parts by weight of (B) a clay filler selected from the class consisting of an organosilane treated clay and an organopolyester treated clay; the sum of (A) + (B) being about 100 parts by weight in the composition; about 1 to about 5 parts by weight based on the sum of (A) + (B) of (C) an organic peroxide crosslinking agent having a half-life at its stock temperature of greater than one hour; and 0 to about 5 parts by weight based on the sum of (A) + (B) of (D) of an organic crosslinking booster;
wherein said components (A), (B), (C) and (D) are such that a crosslinked product obtained upon crosslinking an admixture containing only said components (A), (B), (C) and (D) in the same proportions as (A), (B), (C) and (D) are present in said vulcanizable composition, has a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM
D412-64T at the same temperature employed to crosslink said admixture.

47.

2. A composition as defined in claim 1, wherein the ethylene-vinyl acetate copolymer contains from about 10 to about 35 weight percent of vinyl acetate based on the weight of the copolymer, wherein the clay filler is an organosilane treated clay, and wherein the amount ratio of (A) to (B) ranges from about 40 to about 65 parts by weight of (A) to about 60 to about 35 parts by weight of (B).

3. A composition as defined in claim 2, wherein the organic peroxide crosslinking agent is 1,1-bis(t-butyl-peroxy)-3,3,5-trimethyl cyclohexane.

4. A composition as defined in claim 2, wherein the organosilane treated filler is vinyltris (2-methoxy-ethoxy) silane treated calcined clay.

5. A composition as defined in claim 2, wherein the crosslinking booster is trimethylol propane trimethacrylate.

6. A composition as defined in claim 2, wherein the ethylene-vinyl acetate copolymer contains about 28 weight percent vinyl acetate and has a melt index of about 20, and wherein the amount ratio of (A) to (B) is about 60 parts by weight of (A) to about 40 parts by weight of (B).
48.

7. A composition as defined in claim 6, wherein the organic peroxide crosslinking agent is present in an amount of about 1.5 parts by weight based on the sum of (A) + (B) and wherein said organic peroxide is 1,1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane.

8. A composition as defined in claim 7, wherein the organosilane treated filler is vinyltris (2-methoxy-ethoxy) silane treated calcined clay.

9. A composition as defined in claim 8, wherein the organic crosslinking booster is trimethylol propane trimethacrylate.

10. A composition as defined b 9, wherein the organic crosslinking booster is present in an amount of about 2.5 parts by weight based on the sum of (A) + (B).

11. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed m said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 1 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

49.

12. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 2 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold and recovering the thermoset injected molded product by removing it from said mold.

13 . A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 3 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

50.

14. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 4 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

15. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 5 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

51.

16. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 6 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

17. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 7 into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

52.

18. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process, comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 8, into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

19. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 9, into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold and recovering the thermoset injected molded product by removing it from said mold.

53.

20. A process for preparing a thermoset injection molded product having a hot tensile strength of at least 250 pounds per square inch when measured according to ASTM D412-64T at the mold temperature employed in said process, which process comprises injecting a vulcanizable ethylene-vinyl acetate composition as defined in claim 10, into a preheated mold, said mold having been preheated to a temperature sufficient to crosslink said vulcanizable composition within five minutes, crosslinking said composition in said mold, and recovering the thermoset injected molded product by removing it from said mold.

21. A process as defined in claim 11, wherein said mold had been preheated to a temperature sufficient to crosslink the composition in about three minutes.

22. A process as defined in claim 11, wherein warm runner injection molding was employed, the runner being maintained at about the same temperature as the stock temperature of the vulcanizable composition.

23. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 11.

54.

24. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 12.

25. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 13.

26. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 14.

27. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 15.

28. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 16.

29. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 17.

30. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 18.

55.

31. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 19.

32. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 20.

33. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 21.

34. An article of manufacture comprising a crosslinked thermoset injection molded product produced according to the process defined in claim 22.

56.