AROMATIC POLYMER BLENDS

Abstract: Polymer blends of improved impact strength comprise a solid aromatic polymer such as polystyrene, an elastomeric polymer such as an ethylene/propylene copolymer, and a diblock copolymer of high molecular weight containing a polystyrene block and a hydrogenated conjugated diolefin polymer block as compatibilizer.

Description: AROMATIC POLYMER BLENDS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to blends of aromatic polymer having improved impact strength, and more particularly t blends of aromatic polymer, elastomer and diblock copolymer. 2. Description of the Prior Art Many widely used aromatic polymers, e.g. polystyrene, have an impact strength which is inadequate for som potential uses. It has therefore been proposed to improv the impact strength of such polymers by incorporatin elastomeric polymers in them. However, aromatic polymers ar frequently incompatible with elastomeric polymers, an incorporation of the latter into the former, even if i improves impact strength, can have a seriously adverse effec on other properties such as tensile strength. Representative art in this area of technology is a follows. EP-A-0021488 (Shell) discloses a graft copolyme composition of improved impact toughness. The graf copolymer comprises a monovinylaro atic polymer such a polystyrene, to which is grafted from 2 to 25 % by weight o a rubber which is a mixture of a polybutadiene elastomer and a styrene-butadiene two-block copolymer. The graft copolymer, also termed an interpolymer, may be prepared by mixing the polybutadiene elastomer and styrene-butadiene block copolymer with the vinyl aromatic monomer in the desired proportions and initiating the polymerization. This teaching is directed to high impact polystyrene, but employs the specified graft or interpolymers which have to be produced by the described polymerisation method, rather than the simple compatibilised blends of the instant invention. EP-A-0148002 (Mobil) discloses blends of high impact poly (p-methyl styrene) (HIPPMS) and another polymer having higher environmental stress crack resistance (ESCR) . The HIPPMS component may be a backbone polymer such as ethylene- propylene-diene elastomer grafted with polymeric units derived from PMS. The other polymer in the blend is one having high ESCR, such as polyethylene, polypropylene or polyst rene-polybutadiene diblock. Once again, this teaching is concerned with blends where the elastomer component is grafted to the continuous phase polymer, and where the high ESCR component may be a diblock copolymer; there is no teaching of the three component (at least) simple blends which are the subject of the instant invention. US 3860551 (Dow) teaches a method of making stabl emulsions of mixtures of two immiscible solutions of polymer by using an ABA or AB block copolymer wherein A or B i identical with one of the polymers. The emulsion may be in polymerisable monomer; thus polystyrene and ethylene/ propylene elastomer may be dissolved in styrene monomer wit styrene-butadiene block copolymer as compatibilizer. Although not exemplified, the emulsion may apparently b heated to initiate polymerisation of the styrene solvent, thereby producing a normally solid thermoplastic product. Such a product, by virtue of its method of preparation, woul comprize a graft copolymer. There is no teaching of th simple non-chemically bound blends which are the subject o the instant invention. Moreover this teaching makes n mention of the hydrogenated block copolymer required by th instant invention. US 3907930 (Monsanto) teaches the dispersion of bloc copolymers such as styrene butadiene, as small particles in polymer blend. Such blend may comprise an aromatic polyme such as polystyrene, and a diene rubber. However the dien rubber, eg polybutadiene, is grafted to the aromatic polyme and also contains said polymer as occlusions : again, not simple blend of polymeric components. Moreover, there is n suggestion to use the block copolymer in its hydrogenate form. US 3972963 (Mobil) teaches the preparation of organic reinforcing fillers for rubber by anionic initiated slurry polymerization of styrene and divinylbenzene in the presence of a block copolymer dispersant that controls the particles of the resulting crosslinked polymer to a fine size. The divinyl benzene functions as crosslinking agent, and polymerization conditions are adjusted such that the product contains groups which are reactable with rubber in a normal rubber cure operation. This teaching exemplifies compounding the organic filler with rubber such as SBR under curing conditions to yield a reinforced rubber of improved physical properties. In each case the originally present block copolymer dispersant has been used up in the filler preparation process and does not exist as a free (compatibilizing) component in the final blend. Moreover, there is no suggestion to use the block copolymer in its hydrogenated form. US 4219466 (Asahi-Dow) discloses blends of monovinyl aromatic polymer such as polystyrene, polystyrene-butadiene block copolymer and amorphous alpha-olefin polymer or copolymer, in combination with a halide flame retardant and an antimony compound. The block copolymer and amorphous polymer are necessarily present to obviate the effects of the flame retardant and antimony compound (reduced toughness, poor mould release properties) . This teaching contains no suggestion of the superior blend properties brought about by using a hydrogenated block copolymer in combination with an elastomer component. Nor does it suggest that the modifier system would be valuable for modifying the impact properties of polymers such as polyphenylene oxide derived from other than monovinyl aromatic monomers. US 4277575 (General Electric) teaches blends of polystyrene and polyphenylene oxide which are impact modified by a synergistic combination of a polystyrene/saturated rubber diblock copolymer and a polystyrene/ethylene-butene rubber/polystyrene triblock copolymer. The blends necessarily contain the triblock component, which is not an elastomeric component as required by the instant application, by virtue of its polystyrene blocks. Such blocks are detrimental to the blends, since their presence means that weight for weight, the modifier is less effective and in any case such triblock copolymers are extremely expensive compared with commercially available random (co)polymer elastomers as contained in the blends of the instant invention. US 4491648 (Shell) discloses thermoplastic molding compositions comprising (a) a selectively hydrogenated ABA triblock copolymer where A is a monoalkenyl arene polymer, such as polystyrene-polybutadiene-polystyrene (SBS) ; (b) a vinyl aromatic copolymer comprising a vinyl aromatic compound and an alpha, beta unsaturated cyclic anhydride, such as styrene-maleic anhydride copolymer; (c) polycarbonate; and (d) a hydrogenated diblock copolymer such as polystyrene- polybutadiene. Insofar as component (a) may be considered to be a form of elastomer, it is not a simple elastomer free of thermoplastic polyer units as is required by the instant invention. US 4584338 (General Electric) discloses polycarbonate molding compositions comprising polycarbonate, hydrogenated AB diblock copolymer such as hydrogenated polystyrene-isoprene or butadiene, and optionally a multiphase composite interpolymer comprising an alkyl acrylate based elastomeric phase and a methacrylate based rigid thermoplastic phase. This interpolymer contains thermoplastic blocks and hence is not a simple elastomer free of thermoplastic polymer units, as is required for blends of the instant invention. US 4612348 (Dow) discloses a method for producing a rubber concentrate which comprises polymerising a monomer system such as styrene or acrylonitrile/styrene in the presence of a low molecular weight rubber and a high molecular weight rubber, to form a blend in which the rubbers are grafted to the polymerised monomers. Such blends ca then be introduced into eg polystyrene or acrylonitrile- butadiene-styrene copolymer to modify the propertie thereof. In such blends, the rubber components have bee grafted to the other polymer components during polymerisatio and are unseparable therefrom, unlike the simple blends o the instant invention. SUMMARY OF THE INVENTION The present invention provides novel polymer blends base on aromatic polymers which have an impact strengt significantly greater than that of the aromatic polymer and tensile strength which is not significantly diminishe compared with the aromatic polymer by itself. This result i achieved by incorporating into the aromatic polymer a elastomeric polymer and a compatibilising agent in the for of a diblock copolymer of specific structure and molecula weight. This diblock copolymer promotes the ho ogenisatio of the aromatic polymer and elastomeric polymer which, in it absence, are incompatible and thus makes possible a improvement in the impact strength unaccompanied by an significant adverse effect on the tensile strength. The polymer blends in accordance with the present invention comprise: (1) as continuous phase, from 40 to 95% by weight of the blend of a solid aromatic polymer; (2) as discontinuous phase, from 2 to 50% by weight of the blend of an elastomeric polymer which does not comprise thermoplastic polymer units; and (3) as compatibiliser for (1) and (2) , from 2 to 30% by weight of a diblock copolymer of formula A-B where A constitutes 5 to 95% by weight of the copolymer and is a polystyrene block and B constitutes 95 to 5% by weight of the copolymer and is a hydrogenated block of a conjugated diolefin polymer, the said block copolymer having a number average molecular weight of at least 80,000. DETAILED DESCRIPTION OF THE INVENTION The solid (at room temperature) aromatic polymer constitutes 40 to 95%, preferably 50 to 95%, more preferably 70 to 90%, by weight of the blend. The aromatic polymer constitutes the continuous phase in the blends of the invention, with the elastomeric polymer constituting the finely dispersed discontinuous phase and the diblock copolymer acting as a compatibilising agent between the two. It is believed that the A block component of compatibiliser (3) becomes incorporated in the aromatic polymer phase (1) and thus effectively contributes to the amount of this continuous phase in the blend. Accordingly it is possible for the aromatic polymer to be the continuous phase of the blend even when it constitutes less than 50% o the blend. The B block of the compatibiliser becomes incorporated in the discontinuous phase (2) . The precis proportions of components (1), (2) and (3) are selected bearing this in mind, and the AB diblock copolymer is chosen so that the blocks have an affinity for the respective continuous and discontinuous phases (although the blocks do not have to be identical with the respective phases to which they have an affinity) . The blends of the invention are therefore properly termed simple blends which may be prepared by simple mixing techniques. They do not require special reactive preparations, and indeed do not constitute grafted blends which are stabilized by virtue of grafts or crosslinks * between the individual polymer components. A wide variety of aromatic polymers can be used i the present invention. Polymers based on monovinyl aromatic monomers, such a styrene. homopolymers or (random or graft) copolymers having, for example, a number average molecular weight from 20,000 to 200,000 are especially preferred. Preferred εtyrene-based copolymers are those in which the comonomer is, for example, acrylonitrile, maleic anhydride, butadiene, or a vinyl ester or unsaturated acid such as (meth)acrylic acid or a (meth)acrylate ester, or a mixture o two or more thereof. The styrene units themselves may be substituted, e.g. with methyl or chlorine in the aromatic nucleus and/or with methyl on the alpha carbon atom. So called high impact polystyrene (styrene graft copolymers) can also be used in the present invention. Such polymers are widely available from numerous different suppliers. Methods of making toughened or high impact styrene polymers are described in US-A-1613673; 2616864; 2623863; 2862906; 2886553; and 2694692, all incorporated herein by reference. Other types of aromatic polymer which can be used in the present invention include polyphenylene ether resins, for example the polymers obtained by oxidative coupling polymerisation of one or more phenol compounds such as phenol itself or substituted derivatives thereof such as the creεols, dimethyl-phenols, phenyl-phenols, e.g. 2-methyl 6-phenyl phenol, and copolymers including residues of more than one type of phenol including those already mentioned and polyhydric phenols such as bisphenol-A, resorcinol, hydroquinone, and substituted derivatives thereof. Such polyphenylene ether resins can be made for example by the processes described in US-A- 3306874, 3306875 and 3257357 all incorporated herein by reference. The polyphenylene ether resins preferably have an intrinsic viscosity of less than 0.4 dl/g as measured in chloroform at 30°C. The compositions of the invention may also comprise, as the aromatic polymer, amorphous aromatic polyamides obtained by polycondensation of a dicarboxylic acid such as alpha,omega-alkane dicarboxylic acid of 4 to 10 carbon atoms, iεophthalic acid, or terephthalic acid, with a diamine suc as an alpha,omega-alkylene diamine of 2 to 6 carbon atom which may be substituted on the nitrogens and/or on th alkylene group by methyl, or meta or paraphenylene diamine. Such aromatic polyamides contain at least 50% of unit derived from an aromatic dicarboxylic acid and/or an aromati diamine. Polyphenylene sulphide analogues of the aforesai polyphenylene ether polymers can also be used, as can b polyphenylene ether ketone resinε. Aromatic resins suitable for use in the presen invention are available commercially. Blends of such resin can be uεed. Preferably blendε of polyεtyrene an polyphenylene ether resins are used as component (1) , in weight ratio of 99:1 to 1:99, more preferably 80:20 to 20:8 and especially 60:40 to 40:60. The blends of the present invention contain 2 t 50%, preferably 5 to 25% by weight of the blend, of a elastomeric polymer comprising the discontinuous phase. Suc polymer component (2) preferably has an E modulus (a determined by ASTM D638) less than 400 MPa, and usually i the range of 1 to 150 MPa. Such elastomeric polymers may b natural, e.g. natural rubber or gutta percha, or synthetic. Synthetic polymers may, more particularly, be elastomeric homo- or co-polymers of alpha olefins of 2 to 20, usually 2 to 10 and especially 2 to 6, carbon atoms; conjugated diolefins of 4 to 6 carbon atoms, e.g. 1,3-butadiene or isoprene; non-conjugated aliphatic dienes of 4 to 16, usually 4 to 8, carbon atoms; and those elastomeric copolymers containing low levels of vinyl substituted monomers such as styrene, alpha methyl styrene, alkyl (meth)acrylates and substituted alkyl (meth)acrylates (the " comonomer levels must be sufficiently low that chains of such monomer units are not formed in the copolymer, which would give it undesirable thermoplastic block propertieε) . The elaεtomeric polymer may contain halogen substituents. Examples of especially suitable elastomeric polymers for use in the present invention include ethylene/propylene elastomers and similar copolymers based on ethyiene and olefins of 3 to 20 carbon atoms, and other synthetic rubbers such as those based on butadiene or chlorinated butadiene polymers, ethylene/propylene/diene terpolymers (EPDM) , butyl and halobutyl rubbers, and elastomeric olefinic polymers of high impact strength, e.g. low density polyethylene. Elastomeric polymers of these various kinds are generally available commercially, and may be considered to be simple or pure elastomers which do not contain substantial amounts of thermoplastic polymer units or blocks in their polymer chains. The presence of such thermoplastic units o blocks generally reεults in blendε having higher mel viscosities, which are therefore more difficult to mix, henc more energy intensive and hence more expensive. Furthermor those elastomers which do contain subεtantial amountε o thermoplastic units are unsuitable since on a weight fo weight basis, more of the polymer has to be incorporated t obtain the desired amount of impact modification, compare with simple or pure elastomers. Preferably, therefore, th elastomeric polymer component is thought of as a rando (co)polymer, without substantial thermoplaεtic blockε in it εtructure. The polymer blendε of the preεent invention includ 1 to 30% by weight, preferably 2 to 15% by weight and mor preferably 5 to 10% by weight, of the blend of the dibloc copolymer. From 5 to 95% by weight of the copolymer, usually 5 to 50%, and especially 20 to 35% by weight of th copolymer, consists of a polystyrene block which may includ alkyl (e.g. methyl) subεtituentε on the aromatic ringε and/o on the alpha-carbon atomε and halogen substituents on th aromatic ringε. The εecond block of the copolymer iε derive from a conjugated aliphatic diolefin of preferably 4 to carbon atoms, e.g. 1,3-butadiene or isoprene, and iε partl or preferably completely hydrogenated. The molecular weigh of the block copolymer must be greater than 80,000 and is preferably in the range 120,000 to 300,000 as determined by gel permeation chromatography using standard polystyrene calibration. Such block copolymers are generally commercially available and it is especially preferred to use the block copolymer sold under the trademark Kraton-G1702X by Shell. It is a feature of blends according to the invention that they have (compared with the continuous phase aromatic polymer alone) an improvement in Izod impact strength with a minimal decrease in tensile strength at break. Preferred blends of the invention, which find use as e.g. automotive parts and household appliance housings, are those wherein the Izod strength improvement is at least 100%, more preferably at least 200%, and the tensile strength at break decrease is no more than 40%, more preferably no more than 25%. The particular polymer types and proportions of components (1) , (2) and (3) of the blends are readily selected to achieve the desired blend physical properties. Blends in accordance with the invention may be made by incorporating the three ingredients together in suitable mixing apparatus, e.g. a two-roll mill, internal mixer or extrusion mixer (single or twin screw) , at elevated temperature at which the polymers are in the molten state, e.g. 150 to 300°C. Blending is continued until the blend is homogeneous as determined by microscopic examination, i.e. with a uniformly dispersed elastomer phase. However, it ha been found to be particularly advantageous first to blen components (2) and (3) in a ratio appropriate to yield the desired final blend proportions, and subsequently to let dow this masterbatch into the appropriate aromatic polymer (1) . This two step route generally yields a blend having eve greater Izod impact strength improvement than a blend of th same polymers in the same proportions, prepared in a single mixing stage. Thus the scope of this invention extends to the use of a blend of components (2) and (3) as impact modifier for the continuous phase aromatic polymer component (1) . Preferably in such masterbatch, and hence in the final blend, the polymers (2) and (3) are in a weight ratio of from 10:90 to 90:10, more preferably from 20:80 to 80:20, most preferably from 30:70 to 70:30, and especially about 50:50. The blends of the present invention may include the usual additional ingredients which may be present in suc polymers, e.g. fillers, antioxidants, processing aids and flame retardants. The proportions of such additional ingredients must, of course, not be so great as to interfere with the desired mechanical properties of the blends. The following examples illustrate the invention. EXAMPLES Blends were prepared by mixing the ingredients listed in the following Tables in a two-roll mill operated at 40 rpm at 190°C for 7 minutes. Also shown in the Tables are some physical properties of the blends, namely Izod impact strength (J/m) measured at room temperature in accordance with ISO R 180, and tensile strength at break (MPa) measured in accordance with ASTM D638. C εrr.oo ε .1 en Polvstvrene ' 100 60 80 100 100 100 0 Ξthy1er.e/?rcpy1er.e rubber' 20 Ethylene/prcpylene rubber " 20 Kra cn G1701* 1 Kratcn G1702X 5 Tensile Streng h at break (.' • .?=) ' 35.0 23.2 26.6 - Izcά I-.DBCt Strer.cth 3δ 4S 54 51 66 39 5 (J/:r.) " 1: Polystyrene 156 K of BASF, cf number average molecular weight approximately 100,000, KFR 190 c C/10kg cf 6.7 άg/min. 2: VISTALON 80S cf Exxon Chemical, containing 77% by weig of ethylene and having a Mooney viscosity ML (1+8) at 127°C of 40. 3: VISTALON 606 of Exxon' Chemical , containing 48% by weig of ethylene and having a Mooney viscosity KL (l+8ϊ at 127°C of 63. 4: A polystyrene/hydrogenated polyisoprene block copolyme from Shell, number average molecular weight 95,000, containing 40% by weight of polystyrene. 5: A polystyrene/hydrogenated polyiεoprene block copolyme from Shell, number average molecular weight 134,000 containing 30% by weight of polystyrene. This Table shows that the impact strength of polystyrene is only marginally improved by incorpora ing either an ethylene/prcpylene elastomer by itself cr a diblock ccr.olv~.e bv itself. -. f. Pcvstv er.e ; i C . EO ED εo EO ;hy1er-e/?rcpy1ene :--.-.er 2D 20 20 20 20 Kratcn 0170 Kratcn G1702X 5 • 10 -.er.si.-e Strer.ctn at break (.' • '.?£) 2 .B 22.0 30.0 29.4 26.0 24.1 20.5 27.5 23 It.:- Impact Strength 59 139 130 164 234 150 117 250 27 ' Z '~ ' y _,- - * • ς. ς__ ___, - p. *^ ', c__ The results reported in Table II show that ccmpcsi icns 10, 11, 12, 14, 15 and 16 in accordance with a preferred embodiment of the present invention have substantially improved Izcd impact strength as compared with unmodified polystyrene (see Table I). The lew molecular weight diblock copolymer Kfaton G1701 improves the impact strength when used at 10%, but the degree of improvement obtained at this level, although useful, is substantially less than that obtained with the high molecular weight diblock copolymer Kraton G1702X. Compare composition 12 with ccmDCsiticn 9 and ccmccsiticn 16 with ccm ositicn 13. Ccmoosition i / .6 1 Q 20 21 ..-- Polystyrene 90 80 80 80 80 Kratcn G1701 10 Kratcn G1702X 20 Kraton G1650 6 20 Kratcn G1651 7 20 Kratcn G1&52" 20 C _a::.:.:.ex .:--l.i-,! 20 Te sile stre gt at break (. v .?a) 29.0 17.0 16.4 18.2 16.4 25 zee ioact strεr.ci 53 25 92 169 120 26 3/Λ y ) 1 , 4 , 5 : See Table I . 6, 7 & 8: poly( styrene/hydrogenate butadiene/styrene ) , triblock copolymers from Shell, each containing 30% by weight polystyrene, and having number average molecular weigh of 72,000(6), 172,000(7) and 58,000(8). 9: poly( styrene/butadiene/styrene ) triblock copolymer fro Shell, containing 43% by weight of polystyrene, and a number average molecular weight of 92,700. The results reported in Table III show that incorporation of a block copolymer by itself, whether it a diblock copolymer or a triblock copolymer either leads little or no improvement in the Izod impact strength (compositions 17, 18 and 22), or, if Izod impact strength improved, tensile strength is greatly reduced, compositio 19, 20 and 21. In cne case (composition 18) the impact strength was not improved a d the tensile strength was ba affecte . Ccmoosition 23 24 -. 26 27 28 29 Poivstvrene ' 80 80 60 80 80 60 SO Ethylene/Prcpylene rubber 20 20 20 20 20 20 20 Kraton G1701 5 - - Kratcn G1702X 5 Kratcn G1650 6 Kratcn G1551' Kraton G1652 Cariflex C1513 " ./ensile strength at break (MPa) 23.2 27.8 29.4 10.8 12.9 16.1 15 Izod Imoact εtrenαth 49 89 154 61 46 92 44 (J/m) 1, 2, 4, 5: See Table I 6, 7, 8, 9: See Table III The results reported in Table IV compare compositions 24 and 25 in accordance with the present invention which show improved Izod impact strength with limited adverse effects on tensile strength, with similar compositions in which the Izod impact strength is improved (but in general not substantially) but in which the tensile strength is substantially adversely affected. TABLE V Composition 30 31 32 33 34 Polystyrene 1 80 80 80 80 80 Butyl rubber 20 20 20 Ethylene/propylene rubber 20 Ethylene/propylene rubber J 20 Kraton G1702X 5 10 10 10 Tensile strength at break (MPa) 27.4 30.8 27-4 28 23. Izod ImDact Strenαth 35 84 308 284 274 (J/m) 1, 2, 3, 5: See Table I 10: Butyl 268 of Exxon Chemical, having 1.5 mol% unsaturation, viscosity average molecular weight (Flory 450,000 and Mooney viscosity ML (1+8) at 127°C of 55. The results reported in Table V show that butyl rubber can be substituted for the ethylene/propylene rubbe used in the previous compositions and substantially the sa results obtained. Compositions 31 to 34 in accordance wit the present invention all show improved Izod impact streng as compared with composition 30 which contains no diblock copolymer without substantial adverse effect on tensile strength.

Claims: CLAIMS 1. A polymer blend comprising: (1) as continuous phase, 40 to 95% by weight of the blend of a solid aromatic polymer; (2) as discontinuous phase, 2 to 50% by weight of the blend of an elastomeric polymer which does not comprise thermoplastic polymer units; and (3) as compatibiliser for (1) and (2), 1 to 30% by weight of a diblock copolymer of formula A-B where A constitutes 5 to 95% weight of the said copolymer and is a block of a styrene polymer and B constitues 95 to 5% by weight of the said copolymer and is a block of a hydrogenated conjugated diolefin polymer, the said block copolymer having a number average molecular weight of at least 80,000. 2. A polymer blend according to claim 1 comprising 70 to 90% by weight of the solid aromatic polymer, 5 to 25% by weight of the elastomeric polymer, and 5 to 10% by weight of the diblock copolymer. 3. A polymer blend according to claim 1 [claim 1 or 2] wherein the solid aromatic polymer is a polystyrene or a polyphenylene ether or a mixture thereof. 4. A polymer blend according to claim 1 [any one of claims 1 to 3] wherein the elastomeric polymer has an E modulus in the range 1-150 MPa. 5. A polymer blend according to claim 4 wherein th elastomeric polymer is an ethylene/propylene copolymer, a ethylene/propylene/diene terpolymer, a polymer of conjugated aliphatic diene of 4 to 6 carbon atoms, buty rubber, or halobutyl rubber. 6. A polymer blend according to claim 1 [any one o the preceding claims] wherein the diblock copolymer contain 5 to 50% by weight of a styrene polymer block and 50 to 95 by weight of the hydrogenated conjugated diolefin polyme block. 7. A polymer blend according to claim 6 wherein th diblock copolymer contains 20 to 35% by weight of polystyrene block and 65 to 80% by weight of a hydrogenate block of polybutadiene or polyisoprene. 8. A method of producing a polymer blend accordin to claim 1 [any one of the preceding claims] which comprise forming a preblend of components (2) and (3) , and blendin the preblend and component (1) to form the desired polyme blend. 9. A method according to claim 8 wherein th preblend comprises components (2) and (3) in a weight rati of from 20:80 to 80:20, more preferably from 30:70 to 70:30. 10. The use of a preblend as defined in claim 9 i the production of polymer blends according to claim 1 [an one of claims 1 to 7].

Inventors: HORRION JACQUES PAUL EUGENE JO, OUHADI TRAZOLLAH, HORRION, JACQUES, PAUL, EUGENE, JOSEPH, OUHADI, TRAZOLLAH
Applicants: EXXON CHEMICAL LTD, EXXON CHEMICAL LIMITED
Application year: 1990
Main classification: C08L71
IPC codes: C08L7, C08L9, C08L15, C08L21, C08L23, C08L25, C08L53, C08L71