CA1134974A - Vinyl halide polymer blends with improved impact properties - Google Patents

Abstract

Case 4027/4028/4082 VINYL HALIDE POLYMER BLENDS
OF IMPROVED IMPACT PROPERTIES
ABSTRACT
Mixtures of (1) impact resistant vinyl halide polymers and copolymers modified with MBS or ABS polymeric additives or (2) impact resistant vinyl halide-graft-polyolefin polymer compositions with minor proportions of a mono alkenyl arene-hydrocarbon alkadiene thermoplastic elastomer provide moldable thermoplastic polymer compositions exhibiting improved impact resistance properties.

Description

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BACKGROUND OF THE INVENTION
Polyvinyl halide (inclusive o-f vinyl halide homopolymers as well as copolyrners of vinyl halide ~lith up to about fifty percent of olefinic comonomer copolymerizable with the vinyl halide) is a widely used moldable thermoplastic having a number of favorable technological properties. However polyvinyl halide, e.g. vinyl chloride homopolymer, breaks on impact very eas;ly at ambient temperature and at still lower or suh-ambient temperatures. Thus at ambient temperature, i.e. at about 20 C., correspond~ng to about 69 F., the notched Izod impact resistance of the aforementioned vinyl halide homo- and copolymers is only of the order o~ about 0.4 to less than about 1 ft-lb./in. At sub-ambien~ temperatures, e.g. down to -20 F. or lower, the notched Izod impact resistance of these polymers becomes vanishingly small or ne~ligible. Gen-erally the ambient temperature impact resistance of conventionalvinyl halide polymers is enhanced by rnechanically blending the vinyl halide with a minor proportion, i.e. less than 50%, of an impact enhancing polymeric additive, conventionaliy termed a poly-vinyl halide impact modifier. The aforementioned impact modifiers moderately enhance the ambient temperature impact resistance of vinyl halide polymers, i.e. generally raise the ambient temperature notched Izod impact resistance of the polymer to about 2 to 10 ft-lbs/in. ;
The polymeric additives employed as such modifiers include ~5 polymeric compositions consisting essentially of methyl methacry~
late, 1,3-butadiene and styrene monomer units (which are known generally as "MBS" polymers) as well as polymeric compositions con-sisting essentially of acrylonitrile, 1,3-butadiene and styrene monomer units (which are known generlcally as "ABS" polymers). Un-fortunately the fore~oing polymeric additives, when prepared for use as polyvinyl halide impact modifiers are rela~ively costly.
This is especially so if a blend of the polyvinyl halide and the ; :
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` ~134974 impact modifier which is transparent or transluscent is desired.
In such instances, the M5S or ABS impact modifier must be prepared or synthesized under careful control so as to have about the same refractive index as the vinyl halide resin (which is generally about 1.52-1.55) and thereby maintain the transparency or trans-luscency of the vinyl halide resin.
Accordingly, it would be technologically desirable to replace a portion of the MBS or ABS polymer in an MBS- or ABS-modified polyvinyl halide composition by a polymer which meets the require-ments for impact modification and which, desirably, is also readily available at a refractive index about the same as that of polyvinyl halide.
A readily available class of polymersl namely the block thermo-plastic elastomers of a hydrocarbon alkadiene of 4 to 10 carbon atoms and a mono-alkenyl-substituted aromatic compound of the ben-zene or naphthalene series containing up to 20 carbons ~as typified by the block polymers of l,3-butadiene or isoprene and styrene) is known to have a refractive index about that of the polyvinyl halides (as indicated by "Modern Plastics Encyclopedia 1974-1975", Vol. 51, No. lOA, October 1974, page 563, entry 35 at the fourth and seventh vertical columns). However, as shown in the Examples set forth below, these block polymers are found in general to be incompatible with polyvinyl h'alide. Such incompatibility of polymeric components in a vinyl halide polymer blend can impair the impact resistance of the blend, as well as the transparency or transluscency of the blend and often results in formation, on molding of the blend, of a solid exudate on the surface of the molded blend which imparts an undesirable rough or lumpy handle to the composition.
While the aforementioned MBS or A~S polymeric impact modifier additives moderately enhance the impact resistance of vinyl halide homo- and copolymers, these impact modifiers are relatively in-effective in imparting a satisfactory sub-ambient temperature , ~ ~ ;

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impact resistance to the polymer, i.e. the -20 F. notched, Izod impact r~sistance of -the pol~nler containing the impact modifier is well belo~l 1 ft-lb./in. and usually is about 0.4 to 0.5 ft-lb/in.
It has been discovered that polymerization of vinyl halide (or a monomer mixture oF vinyl halide and copolymerizable ethy-lenically unsaturated comonomers) in t:he presence of a hydrocarbon polyolefin elastomer results in a polymer product (a vinyl halide-graft-polyolefin polymer) which contains vinyl halide polymer chains bound, i.e. grafted, at random points along the chain of the trunk olefin polymer as well as ungrafted vinyl halide polymer.
The graft polymer product, especially the graft polymer product prepared by a liquid phase bulk polymerization reaction, has a sub-stantially enhanced impact resistance at both ambient temperature and sub-ambient temperatures compared to the aforementioned con-ventional, i.e. ungrafted, vinyl halide polymers even when thelatter are blended with a conventional polyvinyl halide impact modifying polymer additive. The bulk polymerization-prepared graft polymer product is even distin~uished from the corresponding graft polymer prepared by a non-bulk polymerization technique, e.g.
suspension polymerization, by an enhanced impact resistance at both low and ambient temperature and by breakage by the desirable ductile breakage mode rather than by an undesirable brittle breakage mode.
Although the ~forementioned graFt polymer possesses a sub-ambient low temperature impact resistance substantially greater than that of conventional impact modifier-containing vinyl halide polymer compositions, the low temperature impact resistance of the graft polymer is found to decrease on ageing. Thus, for examples a molded article of the graft polymer, on ageing at ambient temper-ature for about one month or longer (or at an elevated temperature for proportionally shorter periods), tends to lose a significant amount, e.g. up to 35%, of its original high low temperature impact resistance. This loss of low temperature impact resistance on ~3~7~

ageing is a particularly serious disadvan-tage when the graft polymer is employed in outdoor applications in a temperate climate wherein sub-ambient temperatures of the order 0 F. to -20 F. or even lower are often encountered during winter months (subsequent to summer months wherein the graft polymer is subjected to relatively high temperatures, e.g. of the order of 80~ - 100 F. or even higher, which serve to accelerate the ageing loss of low temper-ature impact resistance).
SUMM~RY OF THE INVENTION
The invention, in accordance with one embodiment th~reof, is directed to an irnproved -thermoplastic composition which is capable of being molded to an impact resistant article and which comprises a blend of a vinyl halide polymer wherein a major proportion of the monomer units are vinyl halide monomer residues; a polymeric impact modifier for polyvinyl halide selected from the group consisting of (1) a polymer wherein the major proportion o~ the monomer units are methyl methacrylate, 1,3-butadiene and styrene residues and (2) an ABS polymer which has about the same refractive index as said vinyl halide polymer. According to the improvement of the invention the blend also comprises a block thermoplastic elastomer wherein the major proportion of the monomer units are residues of a mono-alkenyl-substitute~ arene of the benzene or naphthalene series of 8 to 20 carbon atoms and a conjugated alkadiene hydrocarbon of 4 to 10 carbon atoms. The block polymer is normally incompatible with said vinyl halide polymer. The vinyl halide polymer is present in a major proportion in the blend, and the polymeric impact modi-fier and the block polymer taken together is present in a minor proportion in the blend. Desirably the weight ratio of said block polymer to said MBS polymer is about 1:5 to about 5:1.
The present impact modifier-block polymer-vinyl halide polymer compositions, when molded under conventional conditions of temper-eture and pressure, are capable of providing molded produc-s having , , :`

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an impact resistance generally greater than those of the corres-ponding composition o-F pol~/inyl halide modified with ~lBS or ABS
polymer alone and of the corresponding composition (i.e. generally an incompatlble mixture) of the polyvinyl halide modified with the block polymer alone. In other words, the combined presence of the MBS or ABS polymer and the block polymer component with the poly-vinyl halide according to the inYention, in general, synergisti-cally enhances the impact resistance of the polyvinyl halide. The components of the polyblend of the invention are inter-compatible eYen on the molding and do not separate as individual solid phases.
Accordingly, the formation of solid exudates (o-f deleterious un-attractive rough handle) on the surface of the present composit10ns does not occur on molding. In general, the combination of MBS or ABS polymer and the block polymer as an impact modifier for poly-vinyl halide according to the invention meets or surpasses all ofthe requirements generally desired in a polyvinyl halide-impact modifier.
In another embodiment, the invention is directed to an improve-ment in a vinyl halide-graft-hydrocarbon polyolefin polymer compo-sition capable of being molded to an impact~resistant article wherein, as the improvement, the composition comprises the afore-mentioned block thermoplastic elastomerg the proportion of block elastomer being about 1% to 20% based on the colnbined weight of the graft polymer and the block elastomer.
The addition of the block elastomer to the gra~t polymer accord-1ng to the invention results in a composition which gains in low temperature impact resistance-l e,g. impact resistance ~t sub-ambient temperature down to temperatures as low as -20 F. or lower, upon ageing of the composition (e.g. at ambient temperature for 1 or more months or under a corresponding accelerated ageing period of 48 hours at 65 C.).

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' - -' '' ' ~iL3~374 Although the non-aged molded blend of the gra-ft polymer and the block elastomer of the invention has a low or sub-ambient tem-perature impact resistance substantially lower than that of the corresponding composition containing only the graFt polymer, age-ing of the graFt polymer-block elastomer mixture enhances the low temperature impact resistance to a value greater than that achieved on ageing the graft polymer in absence of the block polymer addi-tive. In preferred graft polymer-block polymer compositions of the invention as described below, the low temperature impact resistance is enhanced to a value substantially corresponding to the irnpact re-sistance of the corresponding non-aged composition containing the unmodified graft polymer, i.e. the impact resistance at low temper-ature, e.g. -20F., oF such preferred compositions of the invention, after ageing, is no more than about 3-12% less than that oF the non-aged, unmodified graft polymer composition. In other words the ad-dition of the block elastomer to the graft polymer according to a preferred embodiment oF the invention provides, in effect, stabil-ization of low temperature impact resistance of the graft polymer.
It is noteworthy that the enhancement of low temperature im-pact resistance on ageing which is accomplished by the addition of the block polymer to the graFt polymer does not occur with block thermoplastic elastomer additives which are the hydrogenated deri-vatives of the present block thermoplastic elastomers, i.e. deriva-tives of the present block elastomers, wherein the diene-derived monomer residues of the elastomer are hydrogenated to saturate the ethylenic unsaturation in the diene residues. Such hydrogenated block thermoplastic elastomers (manufactured under the general de-signation Kraton* G) when incorporated in the present vinyl halide graft polymers product a loss of low temperature impact resistance on ageing (as is illustrated by the results o-F Example 35 below).

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The incorporation of the presen-t block polymer into the vinyl halide graft pol~mer to provide age-enhancement of low temperatllre impact resistance according to the inven-tion does not deleteriously affect, to any substantial extent, the other desirable properties of the graft polymer such as the heat distortion temperature and the thermal stability of the molten polymer (as measured in a Brabender Plastograph). If desired, the present block polymer-vinyl halide graft polymer compositions may contain impact resistance enhanc~ng additives such as the aforementioned ABS or MBS polymeric addit~ves.
DETAILED DESCRIPTION OF THE INVENTION AND THE
_ _ PREFERRED EMBODIMENTS THEREOF
In the present compositions comprising block polymer, an MBS or ABS impact modif;er and polyvinyl halide, the desired proportion of block polymer and ABS or MBS additive and the ratio of the block polymer to the ABS or MBS additive to provide optimum impact-resis-tance will vary somewhat depending upon the particular ABS or MBS
additive and block polymer employed. The combination of the ABS or MBS constituent and the block polymer constituent is generally present in a minor proportion in the blend of the invention, i.e. is

2~ in the range oF about one to less than about fifty weight percent, preferably is in the range of about 5 to about 20 weight percent, and especially is in the range of about 8 to about lS weight percent.
Similarly the vinyl halide polymer is present in a major proportion, i.e. constitutes more than about 50 weight percent to about 99 weight percent of the blend, and preferably is present at about 80 to about 95 weight percent concentration, especially at about 85 to about 92 weight percent concentration.
T achieve synergistic enhancement of impact resistance accord-ing to the invention, the weight ratio of the block polymer to the MBS polymeric additive is about 1:5 to about 5:1 and preferably is about 1:4 to about 4:1.
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The weight ratio o-F block polymer to the AB5 polymer, i.e.
additive can vary over a wide range, but is desirably about 1:5 to about 5:1 and preferably is about 1:4 to about 4:1.
In the compositions of the invention which comprise a vinyl halide-graft-polymer composition modified with the block thermo-plastic elastomer the proportion of the block thermoplastic elas-torner which is employed to provide enhancement of low temperature impact resistance upon ageing in accordance with the invention i5 generally of the order of about 1% to about 20%. Preferably about 1% to about 15%, and especially about 2% to about 10% of the block polymer based on the combined weight of the vinyl halide graft poly-mer component and the block polymer component is employed.
THE POLYVINYL HALIDE COMPONENT
The vinyl halide polymer employed as a component in the present composition can be made by any of the known polymerization processes used for preparation of these polymer, e.g. vapor phase, emulsion, suspension, solution or bulk liquid phase polymerization. Conven-iently vinyl halide polymers prepared by the bulk liquid phase polymerization mode are employed.
An especially desirable bulk-liquid phase-polymerized polyvinyl halide for use in the invention is obtained by free radical addition polymerization in two reaction stages, i.e. a first stage employing high speed, high shear agitation until conversion of monomer or mono-mers to polymer is about 3 to 15% and a second stage employing low speed, low shear agitation until polymerization is complete. This technique is disclosed in US Patent 3, 522, 227 and British Patent 1,047,489.
The polyvinyl halide resin contemplated for use in the inven-tion is a rigid resin, i.e. a resin containing less than about 10 percent plasticizer or none at all. Typically, the resin i5 a .. , , , . - , . .: ., , . , .:. .. . , . . : ,:

~'~3~74 readily available commercial resin which is processes at a tempe-rature on the order oF about 350F. or even hi~her. While vinyl chloride is the preferred vinyl halide monomer reactant used in prepar;ng the v;nyl halide polymers o~ the invention, other suitable vinyl halide monomers useful in the invention are the alpha-halo-substituted ethylenically unsaturated comPounds which, like vinyl chloride, are capable of entering into an addition polymerization reaction, for example, vinyl fluoride~ vinyl bromide, vinyl iodide, vinylidene fluoride, vinylidene chloricle, vinylidene bromide~ vinyl-idene iodide and the like. Vinyl halide polymers derived Prom polymer;zat;on of two, three or more different v;nyl hal;cle mono-mers can also be used. It ;s to be understood that the polyvinyl halide resin, as contemplated for use in this invention, can be a modified resin, e.g., a copolymer resin of vinyl halide with a minor amount i.e. less than 50 weight percent of the total ~onomer mixture, of a comonomer, e.g. of vinyl acetate, or preferably a copolymer resin prepared by copolymerizing vinyl halide monomer with from about 1 to about 30 weight percent of a comonomer co-polymerizable with the vinyl hal;de. Thus, while the polyvinyl halide component of the invention is preferably comprises totally o~ vinyl chloride homopolYmer, or other vinvl halide homooolvmer, the present invention is also intended to include copolymers thereof as DreviouslY described. Suitable ethylenically unsaturated comonomer materials which can be used to form the base vinyl halide copolymers ~i.e. vinyl halide bipolymers, terpolymers, tetrapoly-mers and higher copolymers, interpolymers, and the like), by the - reaction with vinyl halide include the followîng monoolefinic compounds: ethylene, propylene, butene-1,4,4-dimethylbutene~
decene-l, styrene and its nuclear alpha-alkyl or aryl substituted 3Q derivatives, e.g., o-, m- or p-methyl, ethyl, or butyl styrene;
and halogenated styrenes such as alpha-chlorostyrene~ monoole finically unsaturated esters including vinyl esters, e.g. vinyl acetate, vinyl stearate~ vinyl benzoate, vinyl-p-chlorobenzoates, ~3~L~7~

alkyl methacrylate, e.g., methyl~ e-thyl, propyl and stearyl metha-acrylate, alkyl crotonates, e.g. octyl crotonate; alkyl acrylates, e.g., methyl, 2-ethyl hexyl, stearyl acrylates; hydroxy-ether and tertiary butyla~ino acrylates, e.g. 2-ethoxy ethyl acrylate, iso-propenyl esters, e.g., isopropenyl acetate, isoproPenyl halides,e.g., isopropenyl chloridei vinyl esters of halogenated acids, e.g., vinyl alpha-chloroacetate, and vinyl alpha-bromoprop;onate;
allyl and methallyl esters, e.g., allyl chloride, allyl cyanide;
allyl chlorocarbonate, allyl nitrate, allyl formate and allyl acetate and the corresponding methallyl compounds~ esters of alkenyl alcohols, e.g., beta-ethyl allyl alcohol; halo-alkyl acrylates, e.g., methyl and ethyl alpha-chloroacrylates; alkyl alpha-cyanoacrylates, e.g., methyl alpha-cyanoacrylate; itaconates, e.g., monomethyl itaconate, diethyl itaconate, alcohol (C-3 to C-8) itaconates; maleates, e.g., monomethyl maleate~ diethyl maleate, alcohol (C-3 to C-8) maleates; and fumarates, e.g., monomethyl fumarate, diethyl fumarate, alcohol (C-3 to C-8) fumarates, and diethyl glutaconate; monolefinically unsaturated organic nitriles including, for example, furmaronitrile, acrylonitrile, metha-acrylonitrile, l,l-dicyanopropene-l, and oleonitrile; monoole-finically unsaturated carboxylic acids including, for example, acrylic acid, methacrylic acid, cinnamic acid, maleic, and itaconic acids, maleic anhydride and the like. Amides of these acidsl such as acrylamide, are also useful. Vinyl alkyl ethers and vinyl ethers~
e.g., vinyl methyl ether, vinyl ethyl ether, vinyl 2-chloroethyl ether, vinyl cetyl ether, and the like, and vinyl sulfides, e.g.
vinyl beta-chloroethyl sulfide, vinyl beta-ethoxyethyl sulfide and the like can also be included as can diolefinicaliy unsaturated hydrocarbons containing two olefinic groups in conJugated relation and the halogen derivatives thereof, e.g., butadiene-1,3-, 2-~ethyl-butadiene-1,3; 2,3-dichlorobutadiene-1,3; and 2-bromo-butadiene-1~3 and the like.

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3~74 lHE VINYL HALIDE-GRAFT-POLYOLEFIN
POLYMER COMPONENT _ When the vinyl halide polymer component of the invention is a copolymer, said copolymer can also be a graft copolymer of a vinyl halide (or of vinyl halide and comonomer copolymerizable therewith) and a polyolefin rubber i.e. elastomer, which is characterized by being soluble, partially soluble, or dispersible at ambient or room temperature and pressure in vinyl halide monomer.
The latter known vinyl halide graft copolymers ar~ obtained by polymerizing a mixture of vinyl halide monomer with one or more ethylenically unsaturated comonomers of the type described above (or desirably, a vinyl halide monomer alone) in the presence of the olefin trunk polymer reactant. The polyolefin elastomer or rubber is a homopolymerg bipolymer, terpolymer, tetrapolymer or higher copolymer (especially a homo- or bipolymer of aliphatic olefinic monomers. The olefin polymers can also contain the residue o~ a aliphatic hydrocarbon polyene, e.g. a non-conjugated, linear or cyclic diene, of 14 to 18 carbon atoms as a monomer unit, The aforementioned olefin homopolymers can be obtained by poly-20 merization of a suitable monomer such as ethene, propene, i.e. pro- -pylene, butene-l, isobutene, octene, or 5-methylhexene-1.
i~ Suitable comonomers for use in preparing the polyolefins are those utilized to prepare the olefin homopolymers as listed above, such as propene or butene-l with ethene and the like. Suitable , termonomers are those utilized to prepare homopolymers and co-polymers as disclosed above such as propene, ethene and the like as well as a polyene. Especially suitable polyene-derived ter-i and higher co-polymers can be prepared from olef~n monomer mixtures~
containing up to 15 percent, preferably up to about 6 percent by weight, of the polyene Cpreferably non-conjugated), e.g. 1,4-hexa-diene, dicyclopentadiene, ethylidene norbornene, cyclooctadiene and other dienes with linear or cyclic chains. The polyolefin used may also be a halogenated polyolefin, e.g. a chlorinated, brominated or fluorinated polyolefin but a hydrocarbon polyole~in trunk polymer, ~ i .

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i.e. a polyolefin wherein the carbon atoms are substituted solely with hydrogen, is preferred.
The polyolefins used are characterized by being soluble, par-tially soluble or dispersible at ambien-t temperature and pressure 5 in vinyl chloride monomer, and in having, typically, monomeric units of 2 to 8 carbon atoms. The weight average molecular weight of the olefin polymers, copolymers, terpolymers, and tetrapolymers can vary from about 50,000 to about 1,0()0,000 and higher, but pre-ferably is about 50,000 to about 300,000. Preferred as polyolefin rubbers for use in preparing vinyl halide graft polymers for use in the invention are ethene-propene polyolefin elastomers and ethene-propene-diene polyolefin elastomers.
The vinyl halide-graft copolymers of the polyolefin elastomers are prepared by polymerizing the vinyl halide in the presence of about 0.05 to about 20% preferably about 1 to about 20~, based on the weight of vinyl halide monomer of the above-described polyole-fin rubber. Preparation of such vinyl halide-polyolefin graft co-polymer according to emulsion and suspension polymerization tech-niques is described in G. Natta et al., US Patent 3,812,204.
Preparation of such vinyl halide-polyoleFin graft copolymer by vapor phase and solution polymerization techniques are described, respectively, in J. Dumoulin et al., US Patent 3,7~9,083 and F.M.
Rugg et al., US Patent 2,947,719. Conveniently, the preparation of the vinyl halide-polyolefin graft copolymers useful as the poly-vinyl halide component of the compositions of the invention is ef-fected by a bulk liquid phase polymerization technique as described by A. Takahashi, US Patent 4,071,582; Canadian application Serial No. 290,991, filed November 16, 1977, now Canadian Patent 1,109,181;
and by L. E. Walker, US Patents 4,007,235 and 4,067,928.
It is to be understood that the above-described vinyl halide-polyolefin graft copolymers possess an impact resistance substantially ~3~7~

greater than the impact resistance oF conventional (i e. ungrafted) vinyl halide homopolymers and copolymers. Nevertheless, the impact resistance properties of such graft copolymers is generally further improved by blending with the present MBS or ABS polymer, i.e. addi-tive and block polymer in accordance with the invention.
A vinyl halide-graft-polyolefin polymer composition wherein the polyolefin is a hydrocarbon polyolefin is the substrate em-ployed when it is desired to provide the vinyl halide graft polymer compositions of the invention which are resistant to loss of low temperature impact resistance on ageing.
THE METHYL METHACRYLATE-1,3-8UTADIENE-STYRENE
POLYMER (MBS POLYMER) COMPONENT
The methyl methacrylate-1,3-butadiene-styrene polymers employed as components of the compositions of the invention constitute a read-ily available class of polymers (generally proprietary polymers) which are manu-factured to have a re-fractive index about that of poly-vinyl halide and which are widely employed as impact modifiers for polyvinyl halide resins. The MBS polymers as manufactured for use as polyvinyl halide impact modification agents are generally graft polymers prepared by polymerizing methyl me~hacrylate (and option-ally, in minor proportion to the methacrylate monomer, ethylenically unsaturated comonomers copolymerizable therewith such as acryloni-trile or styrene) in the presence of a polybutadiene or a polybu-tadiene-styrene trunk polymer rubber, as described in L. I. Nass Ed. "Encyclopedia of PVC'', M. Dekker, Inc., Vol. 2, 1977, page 613, Section 2(a). It is well understood that a wide variety of grafting -conditions and choice of comonomers can be employed in the prepara-tion of the MBS-impact modifiers. Typical graft polymerization se-quences and/or comonomers for use with the methacrylate monomer in preparation of the MBS polymer modifiers are disclosed in the follow-ing patents: ~

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K. Saito et al., US Patent 3,~70,052; K. Saito et al., US Patent 3,651,177; K. Saito et al., US Patent 3,287,443; S.S. Feuer, US
Patent 2,943,074; L.E. Daly, US Patent 2,018,26~; L.A. Beer, US
Patent 3,444,269; A.C. Condon, US Patent 3,445,416; T. Tanaka et al., US Patent 3,652,483; S. Yonezu et al., US Patent 3,~52,727;
T. Tanaka et al., US Patent 3,657,39t); S. Koyanagi et al., US
Patent 3,717,68~; Y. Amagi et al., U'i Paten-t 3,775,514; T.J.G.
Lonning, US Patent 3,780,134; T. Tanaka et al., US Patent 3,842,1 4LI;
H. Kumabe et al., US Patent 3,907,928; F.E. Love, US Patent 3,922,320; N. Murayama et al., US Pat:ent 4,021,509; F. Ide et al., US Patent 4,041,106 and S. Koyanagi et al., German Offenlegung-shrift 2,0647297 issued July 1, 1971.
Proprietary MBS polymers manuFactured as impact modification additives for vinyl halide polymers incl~de Acryloid-~ KM229, KM
607-N and KM611 of Rohm and Haas Co. (described in R.P. Petrich, Polymer Eng. and Sci., July 1973, Vol. 13, No. 4, pages 248~258 and in J.T. Lut~, Jr., Adv. in Chem. Ser. No. 134, 1974, pages 61-72, as well as Kane Ace~ B-12 and B-22 manufactured by Kanegafuchi Chemical Industry Co. The latter proprietary MBS
polymer, i.e. Kane Ace~'; B-22, which provides an especially good result when employed as the MBS polymer component of the inven-tion, is prepared in accordance with the technology of the above-mentioned US Patents 3,387,443; 3,651,177 and 3,670,052 of K.
Saito et al.
THE ACRYLONITRILE-1,3-BUTADIENE-STYRENE
POLYMER (ABS POLYMER) C MPONENT _ The acrylonitrile-1,3-butadiene-styrene polymers employed as components oF the composition oF the invention constitute a readily available class of polymers (generally proprietary polymers) which .
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~34~74 are widely employed as impact modifiers for polyvinyl halide resins.
If desired, they are available at about the same refractive index as vinyl halide resins. As recognized by the art the ABS polymers comprise either (1) a mixture of a copolymer of styrene and acrylo-nitrile (typically, at a monomer ratio of 60 to 80:40 to 20 styrene;
acrylonitrile) with a minor amount (e.g. 10~ to 40% by weight) of a copolymer oF acrylonitrile and butadiene (typically at a monomer ratio of 5 to 40:95:5) or (2) a mixture of a copolymer of styrene and acrylonitrile (typically at a monomer ra-tio of 60 to 80:40 to 20) with a minor amount (typically 10% to 40%) of a graft of the latter styrene-acrylonitrile copolymer onto polybutadiene.
The ABS polymers are more particularly described in R.E.
Gallagher, US Patent 3,988,393 and W.C. Calvert, Australian Patent 220,155 (issued April 11, 19~7).
THE BLOCK POLYMER COMPONENT
The block elastomer component of the compositions of the inven-tion is a thermoplastic block polymer wherein the major proportion of the monomer units are derived from (1) a mono-alkenyl-substituted arene (i.e. aromatic compound) of the benzene or naphthalene series containing 8 to 20 carbons and (2) a conjugated hydr-ocarbon alka-diene of 4 to 10 carbon atoms. Minor amounts of other monomers may be present in the block polymer as described herein below.
The monoalkenyl arene of the benzene or naphthalene series employed as a monomer in preparing the block polymer constituent of the present composition can be, for example, styrene; o-, m- or p-methyl styrene; o-, m-, or p-n-butyl-styrene; m-isopropyl-st.yrene;
p-t-butyl-styrene; p-octyl-styrene; 2,3-dimethyl styrene; 3-ethyl styrene; alpha methyl-styrene; p-n-dodecyl-styrene; p-methoxy-styrene; m-n-octylstyrene; l-vinyl-2-n-octyl naphthalene; l-vinyl-2-isopropyl-naphthalene; 1-vinyl-2-methoxy-naphthalene or mixtures thereof. The carbon-to-carbon double bond in the side chain of the :
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alkenyl arene is in alpha, beta position with respect to the aromatic nucleus. Preferably the monoalkenyl-substituted arene is a hydro-carbon and -the alkenyl group is the vinyl group, CH2=CII-. PreFerably also the monoalkenyl-substituted arene is a compound o~ the benzene series, especially an alkenyl-substituted compound of the ben~ene series containing up to 12 carbon atoms. Block polymers prepared usiny styrene as the mono-alkenyl-substituted aromatic monomer are especially preferred.
The conjugated hydrocarbon alkadiene monomer used to prepare ~ the block polymer constituent of the present composition can be, for example, 1,3-butadiene; isoprene; 2,3 dimethyl-butadiene; 2-n-butyl~l,3-butadiene; 1,3-cyclohexadiene; 2-n-hexyl-1,3-butadiene;
1,3-pentadiene; 1,3-hexadiene; 1,3-decadiene; 2-isopropyl-1,3-buta-diene, 2-t-butyl-1,3-butadiene; 1,3-cyclodecadiene; Z~4-octadiene;
or mixtures of the foregoing cyclic or open chain alkadiene hydro-carbons. Preferably the alkadiene monomer employed in the block polymer constituent of the present composition is an open chain alkadiene and especially is l,3-butadiene or isoprene.
While it is preferred that all of the monomer units of the present block polymer constituent consist of residues of the fore-going alkadiene and mono-alkenyl-substitutPd arenes, it is under-stood that, i~ desired, minor proportions of the residues of other ethylenically unsaturated compounds copolymerizable with the alka-diene and the alkenyl-substituted aromatic monomer can be present also as comonomer units, for example residues of vinyl pyridine, acrylonitrile, lower alkyl esters of acrylic acid ~wherein the term lower alkyl indicates a straight or branched alkyl group of 1 to 6 carbon atoms, e.g. methyl), methacrylonitrile, and vinyl carboxy-lates, e.g. vinyl acetate.
The weight ratio o~ the mono-alkenyl-substituted aromatic compound residue to the alkadiene residue can vary over a wide rarge.
However, because of their ready availability, the block polymers i .

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preferably employed in the invention have a ~leight ratio of mono-alkenyl-substituted arene residue -to alkadiene residue in the range of about 1:1 to about 1:10, pre~erably o-F about 1:1.5 to about I:6 and especially of about 1:1.5 to 1:2.3.
The block polymers of the invention are generally prepared by a sequential polymerization of the monomer reactants employing an anionic addition polymerization technique. The reaction is generally carried out in the presence of a catalyst for anionic polymerizat~on, typically an organo lithium catalyst such as n-butyl lithium; (Under the latter reaction conditions a block copolymer is ~ormed substan-tially to the exclusion of formation of a conventional copolymer, i.e. a random, network, or graft copolymer, of the aforementioned monomers). The polymerization reaction is e~fected in an inert atmosphere under substantially anhydrous conditions. The polymer-ization can be carried out in the absence or presence of an inert reaction mixture diluent or solvent such as an ether devoid o~
functional groups containing active hydrogen, e.g. tetrahydrofuran, or an aromatic hydrocarbon such as benzene~ toluene, xylene and the like. Use of an ether solvent is especially advantageous.
The preparation of the aforementioned block polymers is more particularly described in L. M. Potter, U.S. Patent 3,140,182;
R. N. Cooper, U.S. Patent 3,030,846; R. P. Selinski, U.S. Patent 3,287,333; K. J. Silberberg, U.S. Patent 3,380,863, at Col. 3, lines 5-28 and Col. 5, lines 10-40; R. A. Hinton, U.S. Patent 3,452,119; J. K. Craver and R. W. Tess Ed. "Applied Poly~er Science", Organic Coating and Plastics Chemistry Div. o~ American Chem. Soc., 1975, pages 394-429, M. Morton Ed. "Rubber Technology", Van Nostrand-Rheinhold Co., Second Edition, 1973, pages 188, 515-~ 533 and D. C. Allport et al. Ed. "Block Copolymers", Wiley -~ 30 (Halstead Press), 1973, pages 81-87, G. Holden et al., 3,265,765;
; - R. L. Huxtable et al., U.S. Patent 3,1987774; R. E. Dollinger, U.S. Patent 3,297~793; R. E. Dollinger et al., U.S. Patent .
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3,35~,7~3, Encyclopedia of Polymer Science and Technology, Vol. 15, J. Wiley and Sons, 1971 (Supplement) "Styrene-Diene Block Polymers", pages 50~-530; and Encyclopedia of Polymer Science and Technology, Supplement, Vol. 2, J. Wiley and Sons, 1977, pages 129-132.
The aForementioned block polymers can be linear block polymers composed of two homopolymeric segments or blocks (termed a diblock polymer) or three (termed a triblock polymer) or more homopolymeric segments. In the triblock polymers, generally the residues of the mono-alkenyl arene constitute the end block while the residues of -the alkadiene constitute the interior block. The block polymers of the invention can be graded or tapered block polymers wherein, for example, one polymer segment or block o-F the polymer begins with a particular monomer unit and gradually incorporates another monomer unit until at the end, said block is totally composed of the second monomer units. In general, in such tapered or graded block polymers (as in the aforementioned triblock polymers) mono-alkenyl arene residues constitute the end blocks while the alka-diene residues constitute the interior block or blocks.
Block polymers oF a mono-alkenyl-substituted aromatic hydro-carbon monomer (e.g. styrene) and a hydrocarbon alkadiene (e.g.
1,3-butadiene or isoprene) containing tapered blocks are more particularly described at page 395 of the aforementioned Craver and Tess textbook reference; at pages 83-84 of the aforementioned Allport et al. textbook reference and the aforementioned US Patent of Holden et al., 3,265,765.
The block thermoplastic elastomers of the invention can also be of star-like or radial polymeric structure wherein 2, 3, 4 or more homopolymeric blocks (advantageously alkadiene blocks) radi-ate from another, central homopolymeric block (advantageously the mono-alkenyl arene block). The latter radial block polymers can be prepared by charging a small amount of a coupling agent , ,.

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(e.g. a polyfunctional alkenyl arene compound such as 1,4-divinyl benzene or a poly-functional inorganic compound such as silicon te-trachloride) to the partially reacted reaction mass of the afore-mentioned anionic polymerization (whic:h has already sufficiently reacted to form a diblock polymer).
The preparation of b'lock polymers having a star or radial configuration is described by the Craver and Tess textbook refer-ence at pages 395 (Table 11), 421, ancl 422 (Table Vl); by pages 131-132 of the aforementioned article of The Encyclopedia of Polymer Science and Technology, Supplement, Vol. 2; by N. Platzer, .
Chemtech, October 1977, pages 634-641, especially page 637, Column 1, lines 33-35 and Figure 2; by the anonymous article entitled "New Rubber is Backed by Stars", Chemical Week, June 11, 1975, page 35; and especially by R.P. Zelinski et al., US Patcnts 3,078,254 and 3,281,383.
It is emphasized that the aforementioned Figure 2 of the Platzer reference graphically indicates the substantial distinc-tions between the present block copolymers and corresponding con-ventional copolymers (including random, network and graft copolymers). ;
The distinctive physical, mechanical and especially processing pro-perties which distinguish the present thermoplastic block elastomers from conventional elastomers prepared from the same monomers as are employed in block polymers are more particularly discussed in the ;
aforementioned Morton textbook reference.
Block copolymers of styrene and 1,3-butadiene or of styrene and isoprene are readily available as proprietary polymers manu- '' ; factured under the designation "Kraton"~'; by Shell Chemical Co. and under the designation "Solprene"* by Phi'llips Petroleum Co. As in-dicated by the fourth and sixth horizontal lines of the aforemen-30 tioned Table Vl of page 422 of the Craver and~Tess textbook reference, the Kraton* copolymers are linear b10ck polymers (non-hydrogenated) of styrene and l,3-butadiene or isoprene whereas the .,, ,:~
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Solprene copolymers are radial block polymers or are block polymers containing a tapered block wherein the monomer units are derived from styrene and l,3-butadiene.
OPTIONAL ADDITIVES
The compositions of the invention may a1so contain various functional additives, which additives are conventional in the pre-paration of vinyl halide molding compositions. Typically these additives include thermal and/or light stabilizers, as well as external and internal lubricants, and processing aids for the polyvinyl halide or vinyl halide graft polymer.
Stabilizers suitable for use in making the vinyl halide poly-mer compositions of the invention include all of the materials known to stabilize polyv7nyl halide against the degradation action oF heat and/or light. They include all classes of known stabili-zers, both organic and inorganic such as metal salts of mineral acids, salts of organic carboxylic acids, e.g. carboxylic acids of 6 to 18 carbon atoms, organo-tin compounds, epoxides, amine compounds and organic phosphites. Conveniently an organo-tin compound such as a methyl tin mercaptide is employed as stabilizer.
I 20 A more detailed description of suitable stabilizers, lubri-cants and processing aids for incorporation into the compositions of the invention is presented in Belgian Patent 855,764 issued December 16, 1977.
Additional classes of additives known for use in polyvinyl halide resins which can be added optionally to the composition of the invention in addition to the aforementioned stabilizers, lubricants and processing aids include pigments, dyes and fillers as described in L.R. Brecker, Plastics Engineering, March 1976, "Additives 76", pages 3-4.
In general the amount of each type of the aforementioned op-tional additive employed in the present composition is about 0.01 , :

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to about 5 weight percent, preferably about 0.1 to about 3 weight percent based on the total resin composition.
The compositions of the invention are essentially of the rigid vinyl halide resin type which contain no more than about 10 weight percent oF a plasticizer for vinyl halide graft polyrner and preferably are free of said plasticiziny additive. Typical suitable plasticizer additives (which are generally organic com-pounds) conventionally employed in polyvinyl halide compositions include, for example, the esters of aliphatic alcohols of medium chain length, e.g. of 7 to 11 carbon atoms, with phenyl dicarbox-ylic acids, e.g. di-n-octyl phthalate and di-isononyl phthalate as well as organic phosphate esters such as cresyl-diphenyl-phos-phate and octyl di-phenyl-phosphate. The chemical structure and technology of plasticizers conventionally employed in polyvinyl halide compositions is more particularly discussed in L.R. Brecker, op. cit. page 5.
The compositions of the invention can be prepared by milling and mixing techniques conventional for preparing conventional impact-modified vinyl halide polymer polyblends. e.g. conventional MBS or ABS polymer-modi-Fied polyvinyl halide. Generally the com-ponent polymers (and, if desired, the above-described optianal additives) are added as a particulate solid mixture to a roll mill or a Banbury type mixer and milled at an elevated temperature conventional for processing rigid vinyl halide polymer compositions.
The resultant polymer blend obtained as product from the milling and mixing operation is molded by either an injection or compres-sion molding technique to articles of particular desired shapes at elevated temperature and pressure conditions which are conventional in molding rigid polyvinyl halide compositions. Desirably when an MBS- or ABS-modified vinyl halide polymer is employed as the blend substrate, a compression molding technique is employed to prepare the aforementioned articles which can be in various shapes including bars, plates, rings, rods, as well as sheets and films.

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The following examples further illustrate the various aspects oF the invention but are not intended to limit it. Various modi-fications can be made in the invention without departing from the spirit and scope thereof. Where not otherwise specified in this specification and claims, temperatures are given in degrees centi-grade, and all parts, ratios and percentages are by weight.
EXA~PLE 1 A particulate solid mixture of 100 parts of a vinyl chloride homopolymer which is prepared by bulk liquid phase polymerization and has a Notched Izod impact resistance (ASTM Test D-256) in the range of about 0.4 to less than 1 ft.-lbs./in., 6.5 parts of a pro-prietary methyl methacrylate-1,3-butacliene-styrene polymer conven-tionally employed for impact resistance-enhancement of vinyl halide polymers (manufactured by Kanegafuchi Chem. Ltd. under the designa-15 tion Kane Ace* B-22), 6.5 parts of a proprietary styrene-1,3-buta-diene radial block polymer containing about 40~ styrene and about 60~ 1,3-butadiene (manufactured by Phillips Petroleum Co. under the designation Solprenet: 414-P), 2.85 parts of an acrylic polymer processing aid conventionaily employed in processing vinyl halide resins (manufactured by Rohm and Haas Corp. under the designation Acryloid~'~ K-12C-ND), 1.14 parts of a proprietary short chain paraf-fin wax conventionally employed as an internal lubricant in molding vinyl halide polymers (manufactured by Cincinnati-Milacron Co.
under the designation Advawax~ 140), 0.23 parts of a proprietary was which is a derivative long chain (28-32 carbon atoms) montan wax acid which contains a diester of a dihydric alcohol and which .
is conventionally employed as an external lubricant (having some internal lubricant function) in molding vinyl halide polymers (man-ufactured by American Hoechst Corp. under~the designation Wax E~';) and 1.8 parts of a proprietary methyl-tin mercaptide conventionally employed as a heat stabilizer in vinyl halide polymers `
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(manufactured by Cincinnati-Milacron Co. under the designation TM-181) is added to the rolls of an Amil Mill opera-tiny under the following conditions:
Front Roll Temperature 355 - 360~F
Back Roll Temperature 330 - 335F
Roll Speed 48 ft./min.
The ~usion time of the mixture,in the mill is about 10-15 seconds.
The mixture remains on the mill rolls for about 5 minutes with the appearance of the bands of the mixture on the rolls being satis-factory. The mixture is delivered ~rom the mill as a sheet which is allowed to cool to about ambient temperature (about 20).
The resultant polyblend is compression malded as bars 6 inches in length, 6 inches in width and 1/8 inch in thickness employing a large Carver Press which operates under the following sequence of temperature and pressure cond;tions: 3 minutes at 350F., 1000 psi; 2 minutes at 350F., 30,000 to 32,000 psi; and 2 minutes at ambient temperature 30,000 to 32,000 psi.
The resultant molded bar samples are cut to provide bar samples of 1/2 inch width which are notched and tested for Notched Izod Impact resistance at ambient temperature and 20F. substantially in accord with ASTM Test D-256. The results of this test and appearance of the molded bar articles are presented in Table I
below.

Z5 In a series of Examples 2-9, the procedure of Example 1 is repeated substantially as described except that the amounts charged of the methacrylate polymer component, i.e. the MBS additive, and the block polymer component are varied or, in some instances, either the MBS poiymer or the block polymer is omitted. The results of these examples are summarized in Table I below.

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Comparison of the ambient temperature impact resistance results of Examples 1-3 (~Ihich illustra-te the compGsitions o-f the invention and which contain block polymer to ME3S polymer in a ratio of about 1:1 to 4:1 with the ratio of styrene to butadiene in the block polymer being about 2:3) with the corresponding impac-t resistance results of Control Examples 5-6 (which omit the block polymer com-ponent), on the one hand, and of Control Examples 7-9 (wh;ch omit the MBS polymer), on the other hand, indicate that the impact re-sistance of the composition OT the invention is synerg;stically enhanced by the combined presence, according to the lnvent1On, of - both the block polymer and the MBS polymer in a vinyl halide resin blend.
Control Examples 8-9 further illustrate that the block polymer additive by itself in a vinyl halide resin is incompatible with the .15 vinyl halide polymer as especially indicated by the formation of a transparency-impairing surface exudate on the products of these Ex-amples. Control Example 4 illustrates a vinyl halicle containing both an MBS polymer and block polymer wherein, however, the ratio of the latter two additives is outside the ratio of the invention. In the latter Examp1e the ambient temperature impact resistance of the : product is not synergistically enhanced by the Joint presence in vinyl halide polymer of both the MBS polymer and the block polymer.
Moreover, the polymer components of the Example 4 product are in-: compatible with each other as indicated by the sur~ace solid exudate ~5 in the Example 4 product.

A series of illustrative and Control Examples 10-16 similar to these described above in Examples 1-9 is performed employing the procedure of Example 1, substantially as described, except that the :
block polymer employed is a proprietary radial styrene-1,3-butadiene block polymer containing about 30% styrene and about 70~O (manufac-tured by Phillips Petroleum Co. under the designation Solprene ; 411-P). The results of these Examples are presented in lable II:
below.
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Compositions of the invention in Tahle II, i.e. the product of Examples 10, 11 and 12 (~hich have about 1:1 to about 4:1 ratio of block po'lymer to MBS polymer wi-th the ratio of styrene to butadiene in the block polymer being about 1:2.3) are seen to have an enhanced ambient temperature impact resistance compared to that obtainable ~at corresponding concentrations~ in polyvinyl halide-methacrylate polymer compositions devoid of block polymer (of the typé illust-rated in Control Examples 5 and 6 above), polyvinyl halide block polymer compositions devoid of MBS polymer (the products of Control Examples '14-16) or polyvinyl halide compositions containing both MBS polymer and block polymer but at a ratio of the latter two polymeric addit;ves outside that of the invention (the product of Control ~xample 13j. The polyvinyl halide compositions of Table II which contain block polymer but no MBS polymer (the products of Control Examples 14-163 and the polyvinyl halide composition of Table II which contains MBS polymer and b'lock polymer at a ratio other than that of the invention (the product of Control Example 13) are seen to have inferior optical properties compared to the products of the invention illustrated in Examples 10, 11 and 12.
Moreover the polymer component of the products of Control Examples 13-16 are incompat;ble with each other as indicated by the presence of substantial solid exudate on the surface of the products.
EXAMPLES 17-2?
In Examples 179 19 and 21 the results of which are set forth in Table III below the procedure of Example 1 is repeated substan-ially as described above'employing several different proprietary block polymers of a mono-alkenyl substituted arene and an alkadiene ; according to the invention (t'ne particu'lar block polymer employed ' ' ' being identified in the footnotes of the Table). Examples 18, 20 and 22 (the results of which are also presented in Table III) are Control Examples corresponding, respectively, to aforementioned Examples 17, 19 and 21 wherein the MBS polymer component is omitted.
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The products illustrative of the invention in Table III, i.e.
the products of Examples 17, 19 and 21, wherein the ratio of block polymer to MBS polymer is about 1:1, have enhanced optical proper-ties (i.e. transparency or translucency) compared to the products of the corresponding Control Examples 18, 20 and 22 wherein the MBS polymer is omitted. The latter Control Example products also have a solid exudate in their surface which is substantially ab-sent in the products of Examples 17, 19 and 21. These results further substantiate the incompatibility of the block polymer of the invention with vinyl halide polymer when the MBS polymer is omitted.
Comparison of the ambient temperature impact resistance re-sults of the products of Examples 17, 19 and 21 with those oF the i corresponding vinyl halide polymer compositions containing the MBS
i 15 polymer but no block polymer (i.e. the products of above-discussed Control Examples 5 and 6) and with those oF the corresponding vinyl halide compositions containing the block polymer but no MBS polymer (i.e. the product of the appropriate Control Example in Examples 18, 20 and 22) indicates that the ambient temperature impact resistance of the products of Examples 17, 19 and 21 is enhanced synergistically.

1:
1~ A particulate solid mixture of 100 parts of a vinyl chloride 1~ homopolymer which is prepared by bulk liquid phase polymerization and has a Notched Izod impact resistance (ASTM Test D-256) in the range as described in Example 1, 6.5 parts oF a proprietary ABS
(acrylonitrile-1,3-butadiene-styrene) polymer conventionally em-ployed for impact resistance-enhancement of vinyl halide polymers (manufactured by Marbon Division, Borg Warner Corporation under ~; ~ the designation Marbon Blendex~L 401), 6.5 parts of the proprietary styrene-1,3-butadiene radial block polymer of Example 1, 2.85 parts of the acrylic polymer processing aid containing abou-t 13~, ethyl acrylate and 87% methyl methacrylate monomer residues employed in ~ ~ *trademark :: :: ~ :

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! Example 1, 1.14 parts of the proprietary short chain paraffin wax, 0.23 parts o~ the proprietary ~lax derivative is conventionally employed as an external lubricant in molding vinyl halide polymers which is described in Example 1 and 1.8 parts of the proprietary methyl-tin mercaptide heat stabilizer of Example 1 is added to the rolls of a Farrell Mill operating under the following conditions:
Front Roll Temperature 360F.
Back Roll Temperature 240F.
Roll Speed ~8 ft./min.
10 After fusion, the mixture remains on the mill rolls ~or about 5 minutes with the appearance of the bands of the mixture on the rolls being satisfactory. The mixture is delivered from the mill as a sheet which is allowed to cool to about ambient temperature (about 20).
The resultant polyblend is compression molded into sample bars 6 inches in length, 6 inches in width and 1/8 inch in thickness employing a large Carver Press and tested for Notched Izod Impact resistance at ambient temperature and -20F. substantially as described in Example 1. The results of this test and appearance 20 of the molded bar articles are presented in Table IV below.
;~ EXAMPLES 24-30 In a series of Examples 24-25 the procedure of Example 23 is ~j~ repeated substantially as described employing different block polymers as follows:
:
:~ 25 Example 24 - the radial block polymer containing 70% -~
1,3-butadiene and 30% styrene of Example 10 ~ Example 25 - the triblock polymer containing 86% isoprene; ~ and 14% styrene of Example 17.
In series of Control Examples 26-30 the procedure o-f Example 30 23 is repeated substantial1y as described with either the ABS
polymer or the block polymer being omitted. I-n Example 26, the proportion of the ABS polymer is varied while in Examples 28-30, `:~
:
,, ~ ` ` ', ' ~ 1 134~4 . - 32 the block polymer is varied. The block polymer employed in Control ~ Examples 28, 29 and 30 correspond to the block polymers used in ;~ Examples 23, 24 and 25, respectively. The results of all of these Examples are compared uith those oF Example 23 in Table IY bel~vl.
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A comparison of the ambient temperature impact resistance results of Example 23 (which illustrates the composition of the invention) with those of the Control Examples 26-28 indicates that the impact resistance of the composition of the invention is syn-ergistically enhanced by the combined presence, according to theinvention, of both the block polymer and the ABS polymer.
Control Examples 28-30 further illustrate that the block polymer additive by itself in a vinyl halide resin is incompatible with the vinyl halide resin as especially indicated by the Forma-tion of a solid exudate on the sur-Face of the products of these Examples.

To a small heated Prodex Henschel mixer operating at about 3800 rpm and 130F., there is added 1500 g. of a vinyl chloride-graft-polyolefin polymer (9~ graft polymer content) wherein the polyolefin is an ethylene-propylene-ethylidene norbornene terpoly-mer which has been prepared by bulk free radical liquid phase polymerization substantially as described in aforementioned Canadian application Serial No. 290,991, filed November 16, 1977.
After the mixing operation has proceeded for 5 minutes, the tem-perature of the mass is 150F. and there is added 45 g. of a pro-; prietary monohydrous tribasic lead sulfate stabilizer conventional-- ly employed for vinyl halide polymers (manufactured by National ;~ Lead Co. under the designation Tribase AG*) and 15 g. oF a propri-etary dibasic lead stearate stabilizer conventionally employed for vinyl halide polymers (manufactured by National Lead Co. under the designation DS-207). After the mixing has proceeded for an addi-tional two minutes, the temperature of the mixture is about 160F.
:
and there is added to the mix~ure 30 g. of the proprietary proces-sing aid copolymer of ethylacrylate (13%) and methy methacrylate (87~) employed in Example 1. After the mixing operation has pro-ceeded for an additional 5 minutes, the temperature of the mixture is 190F. and there is added to the mixture 15 g. of a proprietary organic :
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lubricant conventionally employed for external lubrication of vinyl halide po1ymers (manufactured by American Hoechst Corp. under the designation XL-165). After the mixing operation has been carried out for an additional 3 minutes, i.e. for a total mixing time of 15 minutes, the temperature of the mixture is 210F. and the mixture is discharged from the mixing apparatus and allowed to cool to ambient temperature.
The resultant mixture is divided into three equal portions which are reserved for milling according to the follow;ng pro-cedure.
To a Farrell Mill operating at the following conditions:Front Roll Temperature 355 ~ 360F.
Back Roll Temperature 330 - 335F.
Speed 48 r.p.m.
there is added 25 g. of the proprietary radical block thermoplastic elastomer of 1,3-butadiene and styrene, employed in Example 10.
The elastomer is milled for 5 minutes and then one of the a-fore-mentioned portions of the above-described mixture is added to the mill. The resultant mixture is milled ~or about 5 minutes and then is sheeted from the mill. The foregoing milling procedure is repeated with the two remaining portions of the mixture from the Prodex-Henschel mixer so that a total of 75 9. of the block elastomer is blended with the vinyl chloride graft polymer.
The sheets obtained from the milling operation are combined and pulverized in a Rapid Granulator. The heat distortion tempe-rature at 264 psi of the resultant mixture is measured in accord-ance with ASTM Test D-648. Also the equilibrium torque and the hea~ stability of the molten mixture in a Brabender Plastograph operating at 204 and 63 r.p.m. is determined.
The pulverulent mixture is charged to an Arburg 200 Injection Molding machine operating at the following cylinder temperature settings, Zone 3 - 320F., ~one 2 - 350F., and Zone 1 - 370F., a mold temperature of 100F. and an injection pressure of 15,000 .
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psi to obtain impact test bar samples 5 inches in length, 1/2 inch in width and 1/8 inch thickness. Some of -these samples are immediately tested for impact resistance (according'to the Notched Izod Impact Resistance Test of ASTM D-256) at bo-th ambient tempe-rature i.e. about 20C. and sub-ambient temperature. i.e. -~0F.
The remaining portion of bar samples are subjected to accel~rated ageing by being heated in a forced clraft oven at 65 for about 48 hours. The aged bars are then tested for impact resistance at -20F. according to the aforementioned procedure of this Example.
The results of the foregoing Example are reported in Table V below.
~XAMPLE 32 .. ... .
The procedure oF Example 31 is repeated substantial'ly as described except that the b'lock thermoplastic elastomer employed is the proprietary radial block copolymer of 1,3-butadiene and styrene of Example 1. The results of this Example are compared with those of Example 31 in Table V below.

-The procedure of Example 31 is repeated substantially as described except that the block thermoplastic elastomer employed is the proprietary triblock copolymer of isoprene and styrene contlaining 86X isoprene and 14% styrene of Example 17. The resu'lts of this Example are compared with those of Examples 31 and 32 in the Table V below.
EXAMPLE 34 (Control) . . .
The procedure of Example 31 is repeated substantially as described except that,the thermop,lastic b,lock elastomer ls omitted.
The results of this Example are compared with those of the pre-ceeding Examples in Table V below.
.
EXAMPLE 35 (Comparative) In a Comparative Example the procedure of Example 31 is re-peated substantially as described except that in place of the block ' .

thermoplastic elastomer of Example 31 there is ernployed a proprie-tary triblock thermoplastic elastomer of l,3-butadiene and styrene which has been selectively hydrogenated to remove ethylenic unsatu-ration in the butadiene residue block (so that the elastomer is, in effect, a triblock polymer having polystyrene end blocks and a mid-block of l-butylene-ethylene copolymer as a result of the hydrogen-ation). The latter hydrogenated thermoplastic block elastomer (the general structure of which is illustrated in Figure 7, page 131 of "The Encyclopedia of Polymer Science and Technology" Supplement, Vol. 2, op cit) is manufactured by Shell Chemical Co. under the designation Kraton GX-6521. The results oF this Example are also set forth in Table V below.
Examples 36-38 (Comparative) The procedure of Example 31 is repeated substantially as de-scribed in Comparative Examples 36-38 wherein the thermoplastic block elastomer of Example 31 is replaced by different thermoplas-tic elastomers not having a block configuration as follows:
Example 36 - a proprietary cross-linked acrylonitrile-1,3-butadiene copolymer containing 41% acrylonitrile conventionally employed as a vinyl halide poly-mer additive (manufactured by B.F. Goodrich ~-~
Chemical Co. under -the designation Hycar* 1411) Example 37 - a proprietary acrylonitrile-1,3-butadiene copoly-mer containing about 33% acrylonitrile (manufac- ~-tured by B.F. Goodrich Chemical Co. under the designation Hycar* 1452P-50) -~
Example 38 - a proprietary acrylonitrile-styrene copolymer ~`
(manufactured by Dow Chemical Co. under the de~
signation Tyril~
The resul~s oF these Comparative Examples are compared with those of Examples 31-35 in Table V below.

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A comparison of the results of the illustrative examples of the invention, i.e. Examples 31-33 with Control Example 3~ (con-taining unmodified vinyl halide graft: polymer) ind;cates that while the addition of the present thermoplastic block elastomers according to the invention to the vinyl halide graft polymer results in an initial lowering of the low temperature impact resistance compared to that of the graft polymer, the low temperature impact resistance of the compositions of the invention increases on accelerated ageing (substantially equ;valent to ageing at ambient temperature for about l month or 10nger~. Compar;son of the results of the aforementioned illustrative Examples with those of the comparative Examples, i.e.
Examples 35-38, indicates that other thermoplastic elastomer addi-tives (including non-block polymers and a block polymer hav;ng structural features distinctive from the additives of the invention as in the block elastomer additive of Example 35) do not impart age-enhancement of low temperature impact res;stance to the graft polymer composition as does the block thermoplastic addit;ve of the invention.
Comparison of the data of vertical columns 33, 34 and 35 of the Illustrative Examples and the corresponding data of Control Example 34 indicates that the fusion time and heat stabiliky (Brabender Plastograph data~ and the heat distortion temperature of the graft polymer are not dim;nished substantially by the admixture of the graft polymer w;th the block thermoplastic elastomer oF the inventian.
Compar;son of the amb;ent temperature ;mpact res;stance of the products of the Illustrative Examples with that of the product of the Control Example ind;cates that the add;tive of the ~inven~ion does not sub-stantially d;minish the ambient temperature impact resistance of the graft polymer on admixture with the graft polymer according to the invention.
The invention has been described in the above specification and illustrated by reference to specific embodiments in the illustrative -examples. However~ it is to be understood that these embodiments are not intended to limit the invention since changes and modifications in the specific details disclosed hereinabove can be made without de-parting from the scope or spirit of the invention.

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Claims

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

In a vinyl halide polymer composition which is capable of being molded to an impact resistant article and which comprises a blend of a vinyl halide polymer wherein the major proportion of the mono-mer units are vinyl halide monomer residues and a polymeric impact modifier for polyvinyl halide selected from the group consisting of (1) a polymer wherein the major proportion of the monomer units are methyl methacrylate, 1,3-butadiene and styrene residues and which has about the same refractive index as said vinyl halide polymer and (2) an ABS polymer, the improvement wherein the blend also comprises a block thermoplastic elastomer wherein the major proportion of the monomer units are residues of a mono-alkenyl-substituted arene compound of the benzene or naphthalene series of 8 to 20 carbon atoms and a conjugated alkadiene hydrocarbon of 4 to 10 carbon atoms, said block elastomer being normally incompa-tible with said vinyl halide polymer, said vinyl halide polymer being present in a major proportion in said blend, and said poly-meric impact modifier and said block elastomer together being present in a minor proportion in said blend, with the proviso that when the polymeric impact modifier is said methyl methacrylate-1,3-butadiene-styrene polymer, the weight ratio of the block elastomer to said modifier is about 5:1 to about 1:5.

The composition of Claim 1 wherein the ratio of the alkenyl arene to the conjugated alkadiene in the block elastomer is about

1:1 to about 1:10.

The composition of Claim 2 wherein the alkenyl arene is a hydrocarbon of the benzene series, the weight ratio of the block elastomer to methacrylate modifier is about 4:1 to about 1:4, the weight ratio of the block elastomer to ABS modifier is about 5:1 to about 1:5 and the ABS modifier has about the same refractive index as said vinyl halide polymer.

The composition of Claim 3 wherein the units of the block elastomer are styrene and 1,3-butadiene or isoprene, the proportion of polymeric impact modifier and the block elastomer in the compo-sition is in the range of about 5 to 20 weight percent based on the weight of the blend, and the weight ratio of the block elastomer to the ABS modifier is about 4:1 to about 1:4.

The composition of Claim 4 wherein the vinyl halide polymer is a homopolymer of vinyl chloride and the proportion of the meth-acrylate modifier and styrene block elastomer in the composition is about 8 to about 15 weight percent based on the weight of the blend.

The composition of Claim 5 wherein the vinyl chloride polymer is a bulk-polymerized polymer of vinyl chloride.

The composition of Claim 6 wherein the block elastomer is a styrene-1,3-butadiene block elastomer.

The composition of Claim 7 wherein the weight ratio of the styrene to the 1,3-butadiene in the block elastomer is in the range of from about 1:1.5 to about 1:3.

The composition of Claim 8 wherein the polymeric impact modifier is the methacrylate modifier.

The composition of Claim 9 wherein the block elastomer is a diblock polymer containing styrene and 1,3-butadiene monomer re-sidues in the weight ratio of about 1:3 and the weight ratio of the block polymer to the methacrylate modifier in about 1:1.

The composition of Claim 9 wherein the block elastomer is a triblock polymer containing styrene and 1,3-butadiene monomer re-sidues in a weight ratio of about 1:3 and the weight ratio of the block polymer to the methacrylate modifier is about 1:1.

The composition of Claim 9 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene monomer residues in the weigth ratio of about 1:2.3 and the weight ratio of the block elastomer to the methacrylate modifier is in the range of about 1:1 to about 4:1.

The composition of Claim 9 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene monomer residues in a ratio of about 2:3 and the weight ratio of block polymer to methacrylate modifier is about 1:1 to about 4:1.

The composition of Claim 8 wherein the polymeric impact modifier is the ABS modifier.

The composition of Claim 14 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene monomer residues in the weight ratio of about 1:2.3 and the weight ratio of the block elastomer to the ABS modifier is about 1:1.

The composition of Claim 14 wherein the block elastomer is a radial block elastomer containing styrene and 1,3-butadiene mono-mer residues in a ratio of about 1:1.5 and the weight ratio of block polymer to ABS modifier is about 1:1.

The composition of Claim 6 wherein the block elastomer is a styrene-isoprene block elastomer.

The composition of Claim 17 wherein the block elastomer is a triblock elastomer containing styrene and isoprene monomer resi-dues in a weight ratio of about 1:6 and the weight ratio of the block elastomer to the polymeric impact modifier is about 1:1.

The impact resistant molded article formed from the composition of Claim 1.

An impact resistant, substantially transparent or transluscent molded article formed from the composition of Claim 3.