CA2141195A1

CA2141195A1 - Composites and polymer compositions for making the same

Info

Publication number: CA2141195A1
Application number: CA 2141195
Authority: CA
Inventors: Deenadayalu Chundury; Anthony S. Scheibelhoffer; Berdine L. Leonard; Ronald E. Thompson; Randall S. Mcallister; Surachai Wimolkiatisak; Anthony F. Dean, Jr.
Original assignee: Individual
Current assignee: Vibrantz Corp
Priority date: 1992-09-21
Filing date: 1993-09-21
Publication date: 1994-03-31
Also published as: AU5135493A; US5385781A; WO1994006627A1; US5264280A; US5374680A

Abstract

This invention relates to a multilayer thermoformable structure comprising (A) at least one cap layer and (B) at least one core layer, and polymer compositions for making the same. The multilayer structures and polymer compositions of the invention are useful in preparing thermoformed articles and are particularly useful in preparing liners for refrigerators and freezers. The multilayer structures and the polymer composition have good thermoformability and chemical resistance. The multilayer struc-tures and the polymer composition have good surface properties including a glossy finish. Further these materials are compatible with new blowing agents, such as the hydrochlorofluorocarbons and hydrofluorocarbon blowing agents, which are more environ-mentally friendly. The layers of the multilayer structure do not require a glue layer.

Description

W O 94/06627 ~ 1 9 ~ PC~r/US93/0897S

Title: Composites and Polymer Compositions Por Making the Same Technical Field of the Invention This invention relates to multilayer structures, such as l~min~nt~, and polymer composition for making the same.
Background of the Invention The multilayer structures and the blended polymer compositions of this invention may be used in a variety of applications incl~lding refrigeration parts, such as inner liners, inner door panels, inner trim, trays and shelves, etc. The multilayered structures and the blended polymers are useful in ~ltpaling parts for: the automotive industry; communic~tinns such as telephones, radio, TV, c~ccpttes~ etc.; power tools; appliances; business m~hinPs; toys;
fu~ ulc;; etc. The multilayered structure and polymers must provide a good quality surface which has a glossy finish and is resistant to chemic~ and scuffing.
When ~l~ing multilayer structures, the layers of the structures must adhere to each other. If the layers of the structure do not adhere to each other a glue, or tie layer is used to stick the layers of the structure together. Layers which adhere to each other without a glue layer are useful.
The concerns about the environm~nt~l affects of chlorofluorocarbons (CFCs) on the earth's ozone layer have led to the development of blowing or foaming agents for foams, such as polyurethane foams used as in~ul~tion. The new blowing agents contain little or no chlorine. One problem associated with the new blowing agents is their chemical attack on the linings of refrigel~tols and rlt;ezel~. A stable and ~h~rnic~lly resistant lining m~t~ri~l for refrigerators and rlee~ is nPe~e~l Summary of the Invention This invention relates to a multilayer thermoformable structure comprising (A) at least one cap layer of a polymer composition comprising (i) at least about 55% by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer s~lect~i from the group con~i~ting of a mono-or dicarboxylic reagent and other vinyl monomers, (ii) from about 0% to about 45% by W 0 94/06627 ~9~ PC~r/US93/08975 weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a un~ul~t~d c~lo~ylic reagent, wherein the block polymer contains up to about 50% by weight bound styrene, and (iii) from about 0%
5 to about 45% by weight of at least one block poiymer of a vinyl aromatic monomer and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a une~hlr~t~ carboxylic reagent, wherein the block polymer contains greater than about 60% by weight bound vinyl aromatic monomer, with the proviso that the cap layer incllldes at least one of (Aii) or (Aiii); and (13) at least one core layer SPl~oct~d from the group con~i~ting of (1) at least one polymer composition comprising (i) from about 50% to about 80 % by weight of at least one polyolefin, (ii) from about 10 % to about 30 % by weight of a polymer of a vinyl aromatic colll~ulld and an ln~hlr~t~1 dicarboxylic acid anhydride or imide, or llli~lulc~s thereof; and (iii) from about 5% to about 20% by weight of a block 15 polymer of a vinyl aromatic colll~ound and a conjugated diene, a partially hydrogen~ted derivative thereof, or a selectively hyd~ogenated deliv~live thereof to which has been grafted a unsaturated carboxylic reagent;

(2) at least one polymer composition comprising (i) from about 50% to about 80% by weight of a polyolefin, (ii) from about 10% to about 30% by weight of a 20 homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer sele~ted from the group con~i~ting of acrylic acid or ester, m~th~ rylic acid or ester, acrylonitrile and maleic anhydride; (iii) from about 5% to about 20% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof 25 to which has been grafted a unsaturated carboxylic reagent;

(3) at least one polymer composition comprising (i) from about 70% by weight of at least one polyolefin, (ii) from about 5% to about 30% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted 30 a lln.~tllrated carboxylic reagent, wherein the block polymer is derived from at least about WO 94/06627 ~ 9 5 PCI/US93/08975 60% by weight bound vinyl aromatic monomer; and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogen~ted derivative thereof, or a selectively hydlogellated derivative thereof to which has been grafted a lln~l",,~ed carboxylic reagent, wherein the polymer is derived from up 5 to about 50% by weight bound vinyl aromatic monomer.
The invention also relates to a polymer composition useful in making multilayered structures. The polymer composition inçlu~es a polymer composition comprising (i) at least about 55 % by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer s~l~ted from the group con~i~ting of a 10 mono or dicarboxylic reagent, (ii) from about 1% to about 45% by weight of at least one block polymer of a vinyl aromatic monomer and an ~liph~tic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer cont~in~ up to about 50% by weight bound styrene, and (iii) from a~out 0.3% to about 45% by weight of 15 at least one block polymer of a vinyl aromatic monomer and a conjugated diene, a partially hydrogenated deAvative thereof, or a selectively hydroge~ ed deAvative thereof to which has been grafted a unsa~u~ d carboxylic reagent, wherein the block polymer contains greater than about 60% by weight bound vinyl aromatic monomer; and a polymer composition compAsing (i) from about 70% by weight of at least one polyolefin, (ii) from 20 about 5 % to about 30% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative thereof, wherein the block polymer is deAved from at least about 60% by weight bound vinyl aromatic monomer; and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic col,lpound and a conjugated diene, or a partially hydrogenated deAvative thereof, wherein the polymer is 25 derived from up to about 50% by weight bound vinyl aromatic monomer.
The multilayer structures and polymer compositions of the invention are useful in ~r~;llg thermoformed articles and are particularly useful in preparing liners for refrigt;l~lols and freeærs. The multilayer structures and the polymer composition have good thermoformability and ch~-mic~l re~i~t~nce. The multilayer structures and the polymer 30 composition have good surface properties including a glossy finish. Further these m~t~ri~l~

Wo94/06627 PCI/US93/08975 ~
9~
-are compatible with new blowing agents, such as the hydrochlorofluorocarbon and hydrofluorocarbon blowing agents, which are more environmPnt~lly friendly. The layers of the multilayer structure do not require a glue layer and are generally recyclable.
I)esc~ ion of the P- ;;~lred Embo~iiment~
Unless the context in(1i-~t~s otherwise, throughout the specification and claims, the amount of the polymers present is determined exclusive of filler or other nonpolymer additive in the polymer composition~. Therefore the amount of each polymer is determined by dividing the weight of the polymer by the combined weight of all polymers present in the co~ osilion.
Ca~p Layer (A) The multilayer structure has a cap layer (A). This cap layer compri~es a polymercomposition comprising a polymer composition comprising (i) at least about 55 % by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer s~le~t~d from the group con~i~ting of a mono- or dicarboxylic reagent and other vinyl monomers, (ii) from about 0% to about 45% by weight of at least one block polymer of a vinyl aromatic monomer and an ~liph~tic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer contains up to about 50% by weight bound styrene, and (iii) from about 0% to about 45%
by weight of at leas~ one block polymer of a vinyl aromatic monomer and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer contains greater than about 60 % by weight bound vinyl aromatic monomer, with the proviso that the cap layer incllldes at least one of (Aii) or (Aiii).
In one embo~limPnt, the cap layer is prepared from polymer compositions which are free of polyamides, e.g. nylon polymers. In another embodiment, the cap layer polymer compositions are free of polyurethane. In another embodiment, the cap layer polymer compositions are free of polyphenylene ether resins. In another embodiment, the cap layer is contains less than 30%, or about 20%, or about 10% by weight polyolefin, such as WO 94/06627 2 1 4 1 1 9 ~i PCr/US93/08975 polymers of ethylene and polyplu~ylene. In another emb~imtont the cap layer is free of polyolefin.
Polymers of Vinyl Aromatic Monomers (Ai) The multilayer structures may include a homopolymer of a vinyl aromatic monomer,5 or a polymer of a vinyl aromatic monomer and at least one monomer sel~cted from the group con.cicting of acrylic acid or ester, m~th~rylic acid or ester, acrylonitrile and maleic anhydride. (Ai) is generally present in an amount from about 50 % , or about 55 %, or about 60% up to about 85%, or to about 80%, or to about 75%, or to about 72% by weight.
The vinyl a~ull.aLic monomer incl~ldes styrene and the various substituted styrenes.
10 In one emb~lim~nt the vinyl aromatic monomer is l~ senLed by the following formula R tC=CH2 ~_ (Z)p 15 wherein R is hydrogen, an alkyl group co~ ing from 1 to about 6 carbon atoms, or halogen; Z is a member s~ te~ from the group concictin~ of vinyl, halogen and alkyl groups con~ g from 1 to about 6 carbon atoms; and p is a whole number from 0 up to the number of replaceable hydrogen atoms on the phenyl nllcle~ls. Specific examples of vinyl aromatic co.l.pounds such as ,~r~;sented by the above formula include, for example, in 20 addition to styrene, alpha-methylstyrene, beta-methylstyrene, vinyl toluene, 3-methylstyrene, 4-methylstyrene, 4-isc LJropylstyrene, 2,4-dimethylstyrene, o-chlolu~yle-le, p-chlorostyrene, o-bromostyrene, 2-chloro-4-methylstyrene, etc. Styreneis the~lc;r~,~d vinylaromatic co---~uul-d.
Specific examples of polymers of vinyl aromatic compounds include poly~Ly,~ne poly(alpha-methylstyrene), poly(p-methylstyrene) and high impact poly~Ly~ne (HIPS).
25 Polystyrene is a ~refelled vinyl aromatic homopolymer. A commercially available polystyrene, which is useful in this invention is Dart 108 polystyrene from Dart Polymer Inc.
In another embo-limPnt, (Ai) is a polymer of a vinyl aromatic monomer and a monomer selected from the group concicting of an unsaturated mono- or dicarboxylic reagent and other vinyl monomers. The carboxylic reagents include carboxylic acids per se and their WO 94/06627 PCr/US93/08975 ~
~4~95 -functional derivatives such as anhydrides, imides, metal salts, esters, etc., which are capable of being forming polymers with the vinyl aromatic morlomer.
The unsaluldted monocarboxylic acid reagents are carboxylic acids and esters corres-ponding to the formula RCH = C(Rl)COOR2 wherein R is hydl~Jgen or a ~~ d aliphatic or alicyclic, aryl, alkaryl or heterocyclic group; R, is hydrogen or an alkyl group; and R2 is hydrogen or an alkyl, aryl, or 10 heterocyclic group. Preferably, R is hydrogen or an alkyl group cont~ining from 1 to about 10 carbon atoms. Preferably, Rl is hydrogen or an alkyl group co~ inin~ from 1 to about 10 carbon atoms. Preferably, R2 is hydl~gell or an alkyl group having from 1 to about 10 carbon atoms. The total number of carbon atoms in R and Rl should not exceed 18 carbon atoms. Specific examples of useful monobasic carboxylic reagents include acrylic acid, 15 mPth~erylic acid, crotonic acid, acrylic anhydride, etc. Specific examples of esters include methyl, ethyl, propyl, and butyl acrylate and methacrylate.
In another embo~im~nt the l~n~AhlrAt~ carboxylic reagent is a dicarboxylic reagent.
An eY~mple of dicarboxylic reagents are maleic reagents. The maleic reagents maygenerally be ~lcsented by the formula R~
1, R-C--C
\~

wherein each R group is hydrogen or an aliphatic or aromatic hydrocarbyl group or the two R groups are joined together to form a fused Ang derivative, X is -O- or >NR2 where R2 is a hydrocarbyl group which may be an aliphatic or an aromatic hydrocarbyl group such as 30 phenyl, methyl, ethyl, propyl, butyl, etc. Preferably both R groups are hydrogen.

Examples of maleic derivatives which are cyclic or bicyclic compounds include those obtained by a Diels-Alder reaction of but~-liene with maleic anhydride or a m~leimi(le.
Those obtained by a Diels-Alder reaction of cyclopent~liçne with maleic anhydride or m~leimi~le, and those obtained by a Diels-Alder reaction of isoprene with maleic anhydride 5 or an N-substituted m~l~imi~e. These cyclic or bicyclic derivatives have high glass transition ~em~l~tures. Examples of dicarboxylic reagents include maleic acid, maleic anhydride, fumaric acid, mesaconic acid, itaconic acid, citraconic acid, itaconic anhydride, citraconic anhydride, monomethyl m~ te, monosodium m~lP~t~, etc.
The copolymers of the vinyl aromatic monomers with maleic anhydride, N-substituted 10 m~leimi~es or metal salts of maleic acid are obtained, in one embo(limt~nt, by polym~ri7ing equimolar amounts of styrene and the co-re~ct~nt, with or without one or more interpolymer-izable comonomers. In another emb~lim~-nt, subst~nti~lly homogeneous copolymers of styrene with maleic anhydride or m~leimi~e or metal salts of maleic acid can be obtained by (1) heating a vinyl aromatic monomer to a temperature at which the vinyl alol"atic monomer 15 will polymerize, (2) stirring the polym~ri7.ing vinyl aromatic monomer while (3) adding maleic anhydride, m~leimide, or the metal salt of maleic acid, or llli~lult;s thereof at a continuous and uniform rate. (~ent-r~lly, the addition of the maleic anhydride, m~leimide, or metal salts or esters of maleic acid is made at a rate in moles per unit time that is slower than the rate, in moles per unit time at which the vinyl aromatic monomer is polym~ri7ing.
20 Procedures for ~repa~ g such copolymers are known in the art and have been described in, for example, U.S. Patent 2,971,939.
In one emb~lim~nt, (Ai) is a styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymers (SMA) are available commercially from, for e~mrle, ARCO under the general trade ~lesign~tion Dylark. Fx~mples include: Dylark DBK-290 reported to 25 comprise about 18% by weight of maleic anhydride and about 82% by weight of styrene;
Dylark 332 reported to comprise about 14% by weight of maleic anhydride and 86% by weight of styrene; and Dylark 134 reported to comprise about 17% by weight of maleic anhydride, the b~l~n~ e being styrene.
Other Dylark m~teri~l~ available include tr~n~p~rent grades: Dylark 132 (Vicat 109-C), Dylark 232 (Vicat 123-C), and Dylark 332 (Vicat 130-C). Impact grades include 2~4~ PCr/US93/08975 ~

Dylarks 150, 250, 350 and 700 which are believed to be blends and/or grafts of SMA with SBR.
Other examples of impact modified styrenic and alpha-methyl styrene copolymers with maleic anhydride and acrylonitrile include Arvyl 300 ~ and 300 CR.
Low molecular weight styrene-maleic anhydri~e copolymers (Mw as low as 1500) also are useful and these are available commercially such as from Monsanto under the de~ign~tion "Scripset" and from Atochem under the design~tion "SMA Resins". Sulfonated sty-rene-maleic anhydride copolymers (and their metal salts) also are available and useful in this invention. Two such products are available from ~toch~-m: SSMA-1000 which is a sulfonated copolymer of about 50% styrene and 50% maleic anhydride; and SSMA 3000, a sulfonated SMA comprising about 75% styrene and 25% maleic anhydride.
Specific eY~mrl~s of copolymers of vinyl aromatic compounds include: styrene-acrylonitrile (SAN); styrene-acrylic acid; and styrene m.oth~rylic acid.
Block Polymers (Aii) The multilayered structure also inçl~l-les a block polymer of a vinyl aromatic monomer and a conjugated diene, a partially hydlogenated derivative thereof, or a selectively hydrogen~t~ derivative thereof to which has been grafted a lln~ ~ carboxylic reagent.
The block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene (Aii) is typically present in an amount from about 10%, or about 15% up to about 30%, or to about 25 % by weight of the polymer colllpo~iLion. The block polymer (Aii) contains up to about 50% bound vinyl aromatic monomer. In one emb~lim~nt, (Aii) contains up to about 48%, or to about 45 % bound vinyl aromatic monomer.
The block polymers, usually block copolymers, may be diblock, triblock, multiblock, starblock, polyblock or graftblock polymers. Throughout this specifi~tion and claims, the terms diblock, triblock, multiblock, polyblock, and graft or grafted-block with respect to the structural features of block polymers are to be given their normal mt-~ning as defined in the literature such as in the Encyclopedia of Polymer Science and Pngin~ring, Vol. 2, (1985) John Wiley & Sons, Inc., New York, pp. 325-326, and by J.E. McGrath in Block Copolymers, Science Technology, Dale J. Meier, Ed., Harwood ~c~ mic Publishers, 1979, at pages 1-5.

WO 94/06627 ~ PCI/US93/08975 Such block polymers may contain various ratios of conjugated dienes to vinyl aromatic monomer. Accordingly, multi-block polymers may be utilized which are linear or radial symmetric or asymmptric and which have structures ~epresenlcd by the form~ A-B, A-B-A, A-B-A-B, B-A-B, (AB)0l2...BA, etc., wherein A is a polymer block of a vinyl 5 aromatic monomer or a conjugated diene/vinyl aromatic monomer tapered polymer block, and B is a polymer block of a conjugated diene.
The block polymers may be prep~cd by any of the well-known block polymPri7~tion or copolym-Qri7~tion procedures incl~1-1ing sequential addition of monomer, increm~nt~l addition of monomer, or coupling techniques as illustrated in, for example, U.S. Patent Nos.
3,251,905; 3,390,207; 3,598,887; and 4,219,627. As well known, tapered polymer blocks can be incol~ cd in the multi-block copolymers by copolym~ri7.ing a lni~lulc of conjugated diene and vinyl aromatic monomer monomers utili7ing the dirrc~ci ce in their copolymeriza-tion reactivity rates. Various patents describe the ~lc~ t;on of multi-block copolymers co~ p tapered copolymer blocks including U.S. Patent Nos. 3,251,905; 3,639,521; and 4,208,356, the disclosures of which are hereby incol~oldtcd by reference.
Conjugated dienes which may be utilized to pl~c the polymers and copolymers are those co~ illg from 4 to about 10 carbon atoms and more generally, from 4 to 6 carbon atoms. Examples include from 1,3-but~ nt~, 2-methyl-1,3-but~ ne (isoprene), 2,3-dimethyl-1,3-but~1iene, chlor~plcne~ 1,3-pent~ ne, 1~3-hPx~iiPne~ etc. Mixtures of these conjugated dienes also may be used. The plcrcllcd conjugated dienes are isoprene and 1 ,3-but~ çne.
The vinyl aromatic monomers which may be utilized to ~r~a~c the copolymers are described above. The plcrelled vinyl aromatic monomer is styrene.
Many of the above-described polymers of conjugated dienes and vinyl aromatic compounds are commercially available. The number average molecular weight of the block polymers, prior to hydrogenation, is from about 20,000 to about 500,000, preferably from about 40,000 to about 300,000.
- The average molecular weights of the individual blocks within the polymers may vary within certain limits. In most in~t~nces, the vinyl aromatic block will have a number average molecular weight in the order of about 2000 to about 125,000, and preferably between about W094/06627 2~ 9~j PCr/US93/08975 ~

4000 and 60,000. The conjugated diene blocks either before or after hydrogenation will have number average molecular weights in the order of about 10,000 to about 450,000 and more preferably from about 35,000 to 150,000.
Also, prior to hydl~genation, the vinyl content of the block polymer is from about 10 to about 80%, and the vinyl content is preferably from about 25 to about 65%,particularly 35 to 55 % when it is desired that the modified block polymer exhibit rubbery elasticity. The vinyl content of the block polymer can be measured by means of nuclear m~gnP.tic lrsO~
Specific examples of diblock polymers include styrene-but~ ne~ styrene-isoprene,and the hyd~genaled derivatives thereof. Examples of triblock polymers include styrene-butadiene-styrene, styrene-isoprene-styrene, alpha-methylstyrene-but~rliene-alpha-methylstyrene, alpha-methylstyrene- isoprene-alpha-methylstyrene, and their partially hydrogenated dt;liv~lives. The diblock and triblock polymers are commercially available from a variety of sources under various tr~en~m~ An example of a commercially available diblock resin in~ des Solprene 314D (l?hillips). A number of styrene-but~ one-styrene triblock polymers are sold by the Shell Ch~mic~l Co~ ,y under the tr~lem~rke "Kraton 2103", "Kraton 2104", and "Kraton 2113". Such thermoplastic rubbery block polymers are made by anionic polymeri7~tion~ and the above three identifi~d Shell Kratons differ in molecular weight and viscosity, and also in the ratio of butadiene to styrene. For example, "Kraton 2103" and "Kraton 2113" have a styrene to but~tiiene ratio of 28:72 while "Kraton 2104" as a styrene to but~1iene ratio of 30:70. Blends of diblock and triblock polymers are also available. Kraton 1118 (Shell) is a blend of SB diblock and SBS triblock polymers. A particularly useful styrene-but~liene block copolymer is Kraton G1701X.
Multiblock polymers of styrene and either isoprene or but~ ne also are commercially available. Commercially available and pl~fellc~d styrene-but~-liene multiblock polymers include Stereon 841A (43% styrene:57% but~iene) and Stereon 845A which are available from The Firestone Tire & Rubber Company.

WO 94/06627 2 1 4 1 1 9 ~ PCr/US93/08975 Radial or starblock copolymers are available from Fina under the general design~tic-n - "Finaprene SBS Polymer". A particularly useful radial or starblock polymer is available commercially under the design~tion "rina~ene 414".
The selective hydrogenation of the block polymers may be carried out by a variety 5 of well known pr~cesses inchl-ling hydrogenation in the presence of such catalysts as Raney nickel, noble metals such as pl~timlm, p~ flillm, etc., and soluble t~n~ition metal catalysts.
Suitable hydrogenation processes which can be used are those wherein the diene-con~
polymer or polymer is dissolved in an inert hydrocarbon diluent such as cyclohexane and hydrogenated by reaction with hydlugen in the presence of a soluble hydrugenation catalyst.
10Such procedures are described in U.S. Patents 3,113,986 and 4,226,952, the disclosures of which are incol~ led herein by reference. Such hydlùgellalion of the block polymers which are carried out in a manner and to extent as to produce selectively hydrogenated polymers having a residual un~l~ tion content in the polydiene block from about 0.5 to about 20% of their original lm~tllr~tion content prior to hydrogen~tion.
15In one embollimPnt the conjugated diene portion of the block polymer is at least 90%
~tllr~ted and more often at least 95% .~~ ed while the vinyl aromatic portion is not significantly hydrogenated. Particularly useful hydl~ge-~ted block polymers are the hydrogenated block polymers of styrene-isoprene-styrene such as an (ethylene/propylene)-s-tyrene block polymer. When a poly~ylene-polybllt~ one-poly~lylene block polymer is 20 hydrogenated, it is desirable that the 1~2-polybut~lienlo- to 1,4-polybllt~ n~ ratio in the polymer is from about 30:70 to about 70:30. When such a block polymer is hydlugenaled, the res--lting product resembles a regular polymer block of ethylene and l-butene (EB). As noted above, when the conjugated diene employed as isoprene, the resulting hydrogenated product resembles a regular polymer block of ethylene and propylene (EP). One example 25 of a commercially available selectively hydrogenated is Kraton G-1652 which is a hydrogenated SBS triblock comprising 30% styrene end blocks and a midblock equivalent is a polymer of ethylene and l-butene (EB). This hydrogenated block polymer is often referred to as SEBS.
In another emb~im~nt, the selectively hydrogenated block polymer is of the formula Wo 94/06627 PCr/US93/08975 ~~,~,4~'~9~

Bn(AB)oAp wherein n = O or l; . "
o is 1 to 100;
5pisOor l;
each B prior to hydrogenation is predo~ tly a polymPri7Pcl conjugated diene hydrocarbon block having a number average molecular weight of about 20,000 to about 450,000;
each A is predo",ii-~n~ly a polymPri7P~ vinyl aromatic monomer block having a number average mol~ r weight of from about 2000 to about 115,000; the blocks of A
con~tituting about 5% to about 95% by weight of the polymer; and the unsaturation of the block B is less than about 10% of the original Im~tl-r~tit)n. In other emb~limPnt~, the lln~tllr~tion of block B is reduced upon hy~ ugenation to less than 5% of its c-rigin~l value, and the average l~n~t--rAtion of the hydrogPn~tPA block polymer is reduced to less than 20%
15 of its original value.
The block polymers of the vinyl aromatic monomer and the conjugated diene may also be grafted with one or more of the above described ~ tP~ monocarboxylic or dicarboxylic reagents. The carboxylic reagents include c~l.o~ylic acids per se and their functional derivatives such as anhydrides, imides, metal salts, esters, etc., which are capable 20 of being grafted onto the selectively hydn~gen~lrd block polymer. The grafted polymer will usually contain from about 0.2 to about 20%, and preferably from about 0.1 to about 10%
by weight based on the total weight of the block polymer and the carboxylic reagent of the grafted carboxylic acid.
In order to promote the grafting of the carboxylic acid reagent to the hydrogenated 25 block polymer, free radical initi~tors are ~ltili7P~, and these initi~tors usually are either peroxides or various organic a_o compounds. The amount of initiator utilized generally is from about 0.01% to about 5% by weight based on the combined weight of the combined polymer and the carboxylic reagent. The amount of carboxylic acid reagent grafted onto the block polymers can be measured by del~. "~ining the total acid number of the product. The ~ W O 94/06627 2 1 ~ 1 1 9 5 PC~r/US93/08975 grafting reaction can be carried out by melt or solution mixing of the block polymer and the carboxylic acid reagent in the presence of the free radical initi~tor.
The preparation of various selectively hydrogenated block polymers of conjugateddienes and vinyl aromatic monomers which have been grafted with a carboxylic acid reagent is described in a number of patents including U.S. Patent Nos. 4,578,429; 4,657,970; and 4,795,782, and the disclosures of these patents relating to grafted selectively hydrogPn~t~d block polymers of conjugated dienes and vinyl aromatic co,l,pou"ds, and the pl~ ;on of such compounds are hereby incorporated by reference. U.S. Patent 4,795,782 describes and gives exarnples of the ~-~dtion of the grafted block polymers by the solution process and the melt process. U.S. Patent 4,578,429 contains an example of grafting of Kraton G1652 (SEBS) polymer with maleic anhydride with 2,5-dimethyl-2,5-di(t-butylperoxy) hexane by a melt reaction in a twin screw extruder. (See Col. 8, lines 40-61.) FY~mrle~ of commercially available maleated selectively hydrogena~ed polymers ofstyrene and bllt~ ne include Kraton FG1901X from Shell, often referred to as a m~lP~tecl selectively hydrogçn~ted S_BS polymer.
Block Polymers (Aiii) The multilayered structure also includes a block polymer of a vinyl aromatic monomer and a conjugated diene, or a partially hydrogenated derivative thereof, or a selectively hyd,ogena~ed derivative thereof to which has been grafted a un~ul~d carboxylic reagent.
(Aiii) is generally present in an amount from about 5%, or about 8% up to about 20%, or to about 15% by weight. (Aiii) contains greater than 60% by weight bound vinyl aromatic monomer. In another embo~im~nt, (Aiii) has greater than about 65%, or greater than about 70%, or greater than about 72% by weight bound vinyl aromatic monomer. The vinylaromatic monomer and the conjugated diene are described above. (See Block Polymer (Aii)).
Examples of useful block polymers having greater than 60% by weight bound vinyl aromatic monomer include Phillips K Resins 03, 04 and 05, available from Phillips Petroleum Company. Generally, the K-Resins have a high poly~yl~ne content such as about 75 %, and these resins are transparent and rigid. One particularly prefel~ed block polymer is K-Resin KR03 from Phillips. A similar m~t~ l (75 % styrene:25 % butadiene) is available from Pina under the ~e~i~n~tion "Finaclear 520".

W 0 94/06627 ~ ~ PC~r/US93/08975 Core Layer (B) The mutilayer structure also çontains a core layer. This core layer may be yl~edfrom one of three polymer compositions or polyolefins described herein, inçl~l-lin~
polyL,lu~ylene. The core layers are ~tt~h~d to the cap layer by means know to those in the S art. In one embodiment the layer are ~tt~ril~l without a glue, or tie, layer between the cap layer and the core layer.
Polymer CoJ~ osilion (Bl) The first polymer composition (Bl) useful in ~l~a,ing the core layer is a polymer composition comprising (i) from about 50% to about 80~o by weight of at least one 10 polyolefin, (ii) from about 10% to about 30% by weight of a polymer of a vinyl aromatic compound and an l~n~~ r~ dicarboxylic acid anhydride or imide, or ~ ures thereof; and (iii) from about 5% to about 20% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogçn~tPd derivative thereof, or a selectively hydrogPn~ted derivative thereof to which has been grafted a lln~t~ t~d carboxylic 15 reagent.
Polyolefins (Bli) The polyolefins employed in the blends of the present invention generally are semi-crystalline or cryst~lli7~hle olefin polymers int~ tlin,~ homopolymers, copolymers, terpolymers, or Illi~lult;s thereof, etc., con~il-h-g one or more monomeric units. The polyolefins (Bli) is generally present in an amount from about 50%, or about 55%, or about 60% up to about 80 %, or to about 75 %, or to about 72 % by weight.
Polymers of alpha-olefins or l-olefins are lJrer~lled in the present invention, and these alpha-olefins may contain from 2 to about 20 carbon atoms. Alpha-olefins coi.l;~ ing 2 to about 6 carbon atoms are prefe~led. Thus, the olefin polymers may be derived from olefins 25 such as ethylene, propylene, l-butene, l-pentene, 4-methyl-1-pçnten~ octene, l-decene, 4-ethyl-1-hPY~nP, etc. ~xamples of polyolefins include polypropylene, polyethylene, and ethylene propylene copolymers.
In one embollim~nt, the polyolefins include polypropylene and ethylene-propylene polymers. (Bli) is generally present in an amount from about 50%, or about 55%, or about 60% up to about 80 %, or to about 75 %, or to about 72 ~o by weight.

~ WO 94/06627 2 1 ~ 1 1 9 ~i PCI`/US93/08975 Propylene polymers may be semi-crystalline or crystalline in structure. The number average molecular weight of the propylene polymers is preferably above about 10,000 and more preferably above about 50,000. In addition, it is ~refell~d in one embodiment that the apparent crystalline meltin,~ point be above about 75C and preferably between about 75C
S and about 250C. The propylene polymers useful in pr~ali"g the polymer blends of the present invention are well-known to those skilled in the art and many are available commercially. Poly~ylene are ~lerelled propylene polymers, and poly~ ylenes suchas Aristech F007S, Aristech F007F (homopolymers), and Shell's 7C06 or Exxon's PD7132 or Aristech's 4007F and 4040F (polyl r~pylene-ethylene copolymers) are particularly ~lcr~llcd.
The propylene polymers include at least one copolymer of propylene and ethylene.The propylene ethylene copolymer will generally contain from about 1 %, or about 4% to about 10%, or about 7% by weight of ethylene. In one embo limPnt the ethylene content is about 6% by weight. In one embo-limPnt the propylene ethylene copolymer is a random copolymer.
Processes useful in p~ g the propylene ethylene copolymers useful in ~lep~ing the present invention are well-known to those skilled in the art and many such copolymers are available commercially. Such random copolymers may be pl~a,cd by any of a number of methods known in the art incl~l~ling those set forth in the Encyclopedia of Polymer Science & Engineering, Vol. 13, 2nd edition, Wiley & Sons, pp. 500-et seq. (and footnotes cited therein), which is fully incol~ldled by reference herein. Propylene ethylene copolymers useful in the present invention are available commercially. Examples of these copolymers include Fina Y-8573 and Z-7650 available from Fina Oil and ~hemic~l Company, Dallas, Texas, U.S.A and Soltex 4208 available from Soltex Polymer Corporation, Houston, Texas, U.S.A.
Vinyl Aromatic Monomer/Carboxylic Reagent Copolymers (Blii) The polymer composition (Bl) also includes a polymer of a vinyl aromatic monomerand an un~l~ carboxylic reagent (Blii). (Blii) is typically present in an amount from about 10%, or about 15% up to about 30%, or to about 2S% by weight of the polymer 30 composition. The vinyl aromatic monomers and unsaturated carboxylic reagents are Pcr/US93/08975 Wo 94/06627 ~4~95 described above. (See Polymers (Ai) and (Aii)). Preferably, the unc~tl-r~t~d carboxylic reagent is a maleic reagent, such as maleic acid, imide, or anhydride.
Block Polymers (Bliii) The polymer col~-posi~ion (Bl) inclu~ies a block polymer of a vinyl aromatic 5 monomer and a conjugated diene, or a partially~llydr~en~t~ delivalive thereof, or a selectively hydrogenated derivative thereof to which has been grafted a lm~~ d carboxylic reagent. (Bliii) is generally present in an amount from about 5%, or about 8% up to about 20%, or to about 15% by weight. The vinyl aromatic monomers and the conjugated dienes are described above. (See Polymers (Ai) and (Aii)). In one embodiment, the block polymer 10 is a multiblock polymer. A particularly useful multiblock polymer is Stereon 841, available commercially from The I~i~c;slone Tire & Rubber Co~..r~-y.
Polymer Co.nl~osi~ion (B2) The core layer may also be formed from a polymer cc,~ o~ilion comrri~ing (i) from about 50% to about 80% by weight of a polyolefin, (ii) from about 10% to about 30% by 15 weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer ~ P~t~A from the group cnn.~ ting of acrylic acid or ester, m~oth~r,rylic acid or ester, acrylonitrile and maleic anhydride; (iii) from about 5% to about 20% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a partially hydl~genated derivative thereof, or a selectively 20 hydrogenated derivative thereof to which has been grafted a un~hlr~t~d carboxylic reagent The polyolefin (B2i), polymer of a vinyl aromatic monomer (B2ii) and the block polymer (B2iii) are described above. (B2i) is generally present in an amount from about 50%, or about 55%, or about 60% up to about 80%, or to about 75%, or to about 72% by weight.
~3lii) is typically present in an amount from about 10%, or about 15% up to about 30%, or 25 to about 25~ by weight of the polymer co~ osiLion. (Bliii) is generally present in an amount from about 5%, or about 8% up to about 20%, or to about 15% by weight.
Polymer Composition (B3) The core layer of the multilayer structure may also be ~ ~ed from a polymer composition comprising (i) from about 70% by weight of at least one polyolefin, (ii) from 30 about 5% to about 30% by weight of a block polymer of a vinyl aromatic compound and a ~ WO 94/06627 2 1 ~ 1 1 9 ~ PCI/US93/08975 conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated d~liv~live thereof to which has been grafted a unsaLul~led carboxylic reagent, wherein the block polymer is derived from at least about 60% by weight bound vinyl aromatic mono,lltl, and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic 5 compound and a conjugated diene, a partially hydr~ge.~ d d~livdLive thereof, or a selectively hydlogellaled derivative thereof to which has been grafted a lln~tllr~t~d carboxylic reagent, wherein the polymer contains up to about 50% by weight bound vinyl ar~"atic monomer.
The il,venlol~ have discovered that the combination of the block polymers with 10 different levels of aromatic content provides improved pr~L~Lies in combination, espe~i~lly with the polyolefins. The polyolefins (B3i) and the block polymer (B3iii) are described above. (See Polyolefin (13li) and Block Polymer (Aii), re~l)ecLively). The low ar~"~aLic content block polymers are described above (see (Aii)). The high ar~".aLic content block polymers are described above (see (Aiii)). Generally, (133i) is present in an amount from 15about 70%, or about 75%, or about 80% up to about 95%, or to about 90%, or to about 88% by weight. (B3ii) is typically present in an amount from about 5%, or aobut 10% up to about 30%, or to about 25%, or to about 20% by weight. (B3iii) is typically present in an amount from about 0.3%, or about 0.5% up to about 15%, or about 10% by weight. In one embodiment, (Bliii) is present in an amount from about 0.3 %, or about 0.5 % up to 2 %, 20or to about 1.5%, or to about 1% by weight.
The high aromatic content block polymer include high styrene content block polymers, such as Stereon 900 available from The Firestone Tire & Rubber Company. The polymer is believed to be derived from about 70% to about 80% by weight sty~ene.
Fillers and Fibers (C) 25The above polymer layers may contain one or more fillers of the type used in the polymer art. FY~mples of fillers employed in a typical compounded polymer blend according to the present invention include talc, calcium carbonate, mica, wollastonite, dolomite, glass - fibers, boron fibers, carbon fibers, carbon blacks, pigment~ such as tit~nium dioxide, or u~es thereof. Preferred fillers are a commercially available talc such as R.T.
30Vanderbilt's Select-A-Sorb, Jet Fil and glass fibers. The amount of filler and fibers included WO 94/06627 PCI/US93/08975 ~
?.~4~9~

in the blended polymers may vary from about 1% to about 70% of the combined weight of polymer and filler. Generally amounts of 5% to about 45%, preferably about 30% to about 40%, are inçl~lde~.
The fillers and fibers may be treated with~coupling agents to improve the bond S between the fillers and fibers to the resin. For eY~mrle~ the fillers can be treated with m~t~ri~l~ such as fatty acids (e.g., stearic acid), silanes, m~ ted polypr~ylene, etc. The amount of coupling agent used is an amount effective to illlprovc the bond between the fillers and fibers with the resin.
Preparation of Polymer Blends The blended polymer compositions of the present invention can be prepared by tech-niques well known to those skilled in the art. For example, a particularly useful procedure is to intim~t~ly mix the polymers using conventional melt mixing equipment such as a mill, a Banbury, a Brabender, a single or twin screw extruder, continuous mixers, kn~Prs, etc.
For eY~mple, the polymers may be in~ Ply mixed in the form of gr~nlllPs and/or powder in a high shear mixer. One ~crellcd process for p~p~ing the blended polymers utilizes the Farrell Compact Pr~ ce~er, CP-23 and CP-57. Short rç~i~en~ times and high shear are readily obtained in a CP-23 and a CP-57. "Tntim~te" mixing means that the mixture is prepared with sl-ffici~nt m.o~h~nical shear and thermal energy to produce a ~lispersed phase which is finely divided and homogeneously dispersed in the continuous or princir~l phase.
The layers such as the cap and core layers be applied by co-extrusion, l~min~ting, etc., or the second layer can be applied from a solution or a dispersion of the cap in water or an organic liquid such as acetone. On drying, a film or cap layer is left on the layer comprising the colll~osiLion of the invention. In another embodiment, multilayered structures can be plc;pared by co-extrusion.
Thermoformed articles having desired shapes can be produced from each of the blended polymer compositions of the present invention by (A) feeding a sheet of the blended polymer composition of the invention to a heating station;
(B) heating the sheet to its sorlening point; and ~ WO 94/06627 ~ 1 ~ 1 1 9 5 PCr/US93/08975 (C) feeding the softened sheet to a forming station where it is thermoformed into articles of the desired shape.
The present invention also includes polymer co"~posilions. More spe~ific~lly, the invention incl~ldes a polymer composition comprising (i) at least about 55% by weight of a 5 homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl ~ulllatic monomer and at least one monomer s~lected from the group con~i~ting of a mono- or dicarboxylic reagent and other vinyl monomers, (ii) from about 1% to about 45% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which 10 has been grafted a un~h-r~ted carboxylic reagent, wherein the block polymer contains up to about 50% by weight bound styrene, and (iii) from about 0.3% to about 45~o by weight of at least one block polymer of a vinyl a,~...alic monomer and a conjugated diene, a partially hydr~genaled derivative thereof, or a selectively hydrugellated derivative thereof to which has been grafted a lln~t~ ~ carboxylic reagent, wherein the block polymer contains 15 greater than about 60 % by weight bound vinyl aromatic monomer. The polymer composition is used in making the cap layer and is described above. The invention also incl~ldes polymer composition comprising (i) from about 70% by weight of at least one polyolefin, (ii) from about 5% to about 30% by weight of a block polymer of a vinyl a~u---atic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated 20 derivative thereof to which has been grafted a lln~tllr~t~ carboxylic reagent, wherein the block polymer is derived from at least about 60 % by weight bound vinyl aromatic monomer;
and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a llne~tllr~ted carboxylic 25 reagent, wherein the polymer is derived from up to about 50% by weight bound vinyl aromatic monomer. The polymer composition is described above as (B3) and is used in making the core layer.
- Various features and aspects of the present invention are illll~tr~ted further in the examples that follow. While these examples are presented to show one skilled in the art how 30 to operate within the scope of this invention, they are not to serve as a limit~tion on the W O 94/06627 PC~r/US93/08975 ~

2~4~9S

scope of the invention where such scope is only defined in the claims. Mol~ovel, in the following eY~mrles, l.lt;p~ ion of blends, compounds, injection molded spe~imPn~, mono layer or l~"~ ted sheets are illllstr~tP~. These eY~mrles serve merely as ill~-~trAtive embo-limPnt~ of the present invention and are not to be considered limiting.
S Unless otherwise in~1ir~tPd in the following examples and elsewhere in the specification and claims, all parts and ~cell~ges are by weight, L~ ~l At~ s are in degrees centigrade and pressures are at or near atmospheric.

Exarnples 1-12 R1P.r~1ed polymer colllposiLions in accordallce with the present invention are prepared on a Farrell Compact Processer, CP-57 at a mixer rotor speed of 500 rpm and extruded at about 220C into strands which are passed through a water bath and air wipe prior to pelletizing. Examples 1- 6 relate to polymer compositions useful in prepa,illg the cap layer of the multilayer structure. Examples 7-12 relate to polymer compositions useful as core layers.

~ W O 94/06627 2 1 ~ 1 1 9 5 PC~r/US93/0897~

Dart 108 (PS) 60 60 60 65 65 70 Stereon 841 10 (43% styrene) Kraton 10 21.9 17.5 18.7 FG19OlX
P~t~d SEBS) Kraton 10 S
G1701x Phillips KR 20 20 13.1 11.3 03 (75%
Styrene) Stereon 900 15 lS
lS (73.5%
Styrene) Stereon 881 lS 17.5 (78 %
Styrene) The following table contains polymer compositions which are useful in ~re~a ing the core layer of the multilayer structure.

W O 94/06627 PC~r/US93/08975 ~
9~

~ristech Tl-4007 (PP~ 67.7 38.86 67.7 38.86 Aristech F007S tPP) 84.2 55.7 Dart 108 tPS) 21.5 12.36 ~rco Dylark 250 ~SMA) 21.5 12.36 Stereon 841 tSB Block) 10.8 6.18 0.7 0.5 Stereon 900 ~SB Block) 15.1 10 Kraton FG1901X
~Haleated SEBS) 0 Phillips KR 03 ~SB Block) Finaprene 414 ~SB Block) 10.8 6.18 ECC Supercoat ~CaC03~ 40 40 Polar 9110 ~Talc) 31 Tio2 2.5 2.5 Lubricant 0.7 Stabilizer 0.1 0.1 0.1 Example 13 A multilayer structure is made by coextruding polymer compositions Examples 6 and 12 above. The polymer composition of Example 12 is placed in an extruder and heated to a melt lelll2eLalule 220C. The extruder is operating at 100 RPM and has a head pres~uie of 2000 psi. The composition of Example 12 is p~ ar~d in a co-extruder. The co-extruder is ope~ g at 125 RPM and has a head ~l~s~ure of 1750 psi. The polymer compositions are co-extruded through a sheet die at 205C. The polymers form a multilayer sheet.
Example 14 The multilayer structure from Example 13 is placed in a standard vacuum forming equipment. The sheet is heated to 177C until the sheet sags about 6 to 13 mm. The mold is closed to form a thermoformable article.

WO 94/06627 ~ 1 4 1 1 9 ~ PCI/US93/08975 . .

Example 15 An eYtruded sheet ~ared as in Example 13 with the composition of Example 5 is heat l~ in~d with an extruded sheet of the product of eY~mple 7 p,e~d by the procedure of example 8 and subsequently thermoformed into cups in a single operation.
Example 16 A two-layer l~min~te is prepaled in the following manner. A 40 mil sheet of the composition of Example 2 is ~lt;p~,d by extrusion. To this sheet is heat l~min~t~d a 12 mil cap layer of example 6.
While the invention has been eYpl~ined in relation to its ~refellcd embodim~nt~) it is to be understood that various mo(lific~tinns thereof will become a~alellt to those sldlled in the art upon reading the specific~tion. Therefore, it is to be understood that the invention disclosed herein is inten~ecl to cover such mo lifir~tit ns as fall within the scope of the appended claims.

Claims

Claims 1. A multilayer thermoformable structure comprising (A) at least one cap layer of a polymer composition comprising (i) at least about 55% by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer selected from the group consisting of a mono- or dicarboxylic reagent and other vinyl monomers, (ii) from about 0% to about 45%
by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer contains up to about 50% by weight bound styrene, and (iii) from about 0%
to about 45% by weight of at least one block polymer of a vinyl aromatic monomer and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer contains greater than about 60% by weight bound vinyl aromatic monomer, with the proviso that the cap layer includes at least one of (Aii) or (Aiii); and (B) at least one core layer selected from the group consisting of (1) at least one polymer composition comprising (i) from about 50%
to about 80% by weight of at least one polyolefin, (ii) from about 10% to about 30% by weight of a polymer of a vinyl aromatic compound and an unsaturated dicarboxylic acid anhydride or imide, or mixtures thereof; and (iii) from about 5% to about 20% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent;
(2) at least one polymer composition comprising (i) from about 50%
to about 80% by weight of a polyolefin, (ii) from about 10% to about 30% by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer selected from the group consisting of acrylic acid or ester, methacrylic acid or ester, acrylonitrile and maleic anhydride; (iii) from about 5% to about 20% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent;
(3) at least one polymer composition comprising (i) from about 70%
by weight of at least one polyolefin, (ii) from about 5% to about 30% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the block polymer is derived from at least about 60% by weight bound vinyl aromatic monomer; and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsaturated carboxylic reagent, wherein the polymer is derived from up to about 50% by weight bound vinyl aromatic monomer.
2. The structure of claim 1 wherein (Ai) is polystyrene.
3. The structure of claim 1 wherein the vinyl aromatic monomer of (A) and (B) is styrene and the conjugated diene of (A) and (B) is independently selected from the group consisting of butadiene and isoprene.
4. The structure of claim 1 wherein the unsaturated carboxylic reagent of (A) and (B) is an unsaturated dicarboxylic reagent.
5. The structure of claim 1 wherein the unsaturated carboxylic reagent of (A) and (B) is maleic acid or anhydride.
6. A multilayer thermoformable structure comprising (A) at least one cap layer of a polymer composition comprising (i) at least about 55% by weight of a homopolymer of a vinyl aromatic monomer, (ii) from about 10%
to about 30% by weight of at least one selectively hydrogenated block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene to which has been grafted a unsaturated carboxylic reagent, and (iii) from about 5% to about 15% by weight of at least one block polymer of a vinyl aromatic monomer and a conjugated diene or a partially hydrogenated derivative thereof; and (B) at least one core layer selected from the group consisting of (1) at least one polymer composition comprising (i) from about 50%
to about 80% by weight of polypropylene or an ethylene-propylene polymer, (ii) from about 10% to about 30% by weight of a polymer of a vinyl aromatic compound and an unsaturated dicarboxylic acid anhydride or imide, or mixtures thereof; and (iii) from about 5% to about 20% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative there;
(2) at least one polymer composition comprising (i) from about 50%
to about 80% by weight of polypropylene or an ethylene-propylene copolymer, (ii) from about 10% to about 30% by weight of a homopolymer of a vinyl aromatic monomer; (iii) from about 5% to about 20% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, or a partially hydrogenated derivative thereof;
(3) at least one polymer composition comprising (i) from about 70%
by weight of polypropylene or an ethylene-propylene copolymer; (ii) from about 5% to about 30% by weight of a high vinyl aromatic content block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative thereof, wherein the block polymer is derived from at least about 60% by weight bound vinyl aromatic monomer; and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative thereof, wherein the polymer is derived from up to about 50% by weight bound vinyl aromatic monomer.
7. The structure of claim 6 wherein the vinyl aromatic monomer of (A) and (B) is styrene and the conjugated diene of (A) and (B) is independently selected from the group consisting of butadiene and isoprene.
8. The structure of claim 6 wherein the cap layer (A) comprises a polymer composition comprising (i) from about 55% by weight of polystyrene, (ii) from about 10%
to about 30% by weight of a selectively hydrogenated block polymer of styrene and isoprene or butadiene to which has been grafted maleic acid or anhydride, and (iii) from about 5% to about 15% by weight of a block polymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof.
9. The structure of claim 6 wherein the core layer (B) comprises the polymer composition (1), wherein (i) is polypropylene, (ii) is a polymer of styrene and maleic acid or anhydride, and (iii) is a block polymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof.
10. The structure of claim 6 wherein the core layer comprises the polymer composition (B2), wherein (i) is polypropylene, (ii) is polystyrene, and (iii) is a block polymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof.
11. The structure of claim 6 wherein the core layer comprises the polymer composition (B3), wherein (i) is polypropylene, and (ii) and (iii) are independently a block copolymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof.
12. The structure of claim 6 wherein the core layer (B) further comprises (D) at least one filler, fiber, or mixture thereof.
13. The structure of claim 12 wherein the filler is talc or calcium carbonate and the fiber is glass fiber.
14. A polymer composition comprising (i) at least about 55% by weight of a homopolymer of a vinyl aromatic monomer, or a polymer of a vinyl aromatic monomer and at least one monomer selected from the group consisting of a mono or dicarboxylic reagent, (ii) from about 1% to about 45% by weight of at least one block polymer of a vinyl aromatic monomer and an aliphatic conjugated diene, a selectively hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsat-urated carboxylic reagent, wherein the block polymer contains up to about 50% by weight bound styrene, and (iii) from about 0.3% to about 45% by weight of at least one block poly-mer of a vinyl aromatic monomer and a conjugated diene, a partially hydrogenated derivative thereof, or a selectively hydrogenated derivative thereof to which has been grafted a unsat-urated carboxylic reagent, wherein the block polymer contains greater than about 60% by weight bound vinyl aromatic monomer.
15. The composition of claim 14 wherein (i) is polystyrene.
16. The composition of claim 14 wherein the vinyl aromatic monomer of (i), (ii), and (iii) is styrene and the conjugated diene of (i), (ii), and (iii) is independently selected from the group consisting of butadiene and isoprene.

17. The composition of claim 14 wherein unsaturated carboxylic reagent of (i),(ii), and (iii) is independently a unsaturated dicarboxylic reagent.
18. The composition of claim 14 wherein the unsaturated carboxylic reagent of (i), (ii), and (iii) is independently maleic acid or anhydride.
19. A polymer composition comprising (i) from about 70% by weight of at least one polyolefin, (ii) from about 5% to about 30% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative thereof, wherein the block polymer is derived from at least about 60% by weight bound vinyl aromatic monomer; and (iii) from about 0.3% to about 15% by weight of a block polymer of a vinyl aromatic compound and a conjugated diene, or a partially hydrogenated derivative thereof, wherein the polymer is derived from up to about 50% by weight bound vinyl aromatic monomer.
20. The composition of claim 19 wherein (i) is polypropylene.
21. The composition of claim 19 wherein the vinyl aromatic monomer is styrene and the conjugated diene is independently selected from the group consisting of butadiene and isoprene.
22. The composition of claim 19 wherein (ii) is derived from about 75%
by weight vinyl aromatic monomer.
23. The composition of claim 19 wherein (ii) is a multiblock polymer.
24. The composition of claim 19 wherein (iii) is a multiblock polymer.
25. The composition of claim 19 wherein (i) is present in an amount from about 75%, (ii) is present in an amount from about 10% to about 20%, and (iii) is present in an amount from about 0.5% to about 1%, wherein the percentages are by weight. 26. A polymer composition comprising (i) from about 70% by weight of polypropylene;
(ii) from about 5% to about 25% by weight of a block polymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof, having about 70% by weight bound styrene;

(iii) from about 0.3% to about 15% by weight of a block polymer of styrene and isoprene or butadiene, or a partially hydrogenated derivative thereof, having up to 60% by weight of bound styrene.
27. The structure of claim 26 further comprising (iv) at least one filler, fiber, or mixture thereof.