公开(公告)号：US4460742A

公开(公告)日：1984-07-17

申请号：US324269

申请日：1981-11-23

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

IPC分类号： C08L101/00 ,  C08L1/00 ,  C08L7/00 ,  C08L21/00 ,  C08L23/00 ,  C08L23/06 ,  C08L25/14 ,  C08L27/00 ,  C08L27/06 ,  C08L33/00 ,  C08L33/02 ,  C08L33/06 ,  C08L33/08 ,  C08L33/10 ,  C08L51/00 ,  C08L51/02 ,  C08L55/02 ,  C08L67/00 ,  C08L77/00 ,  C08L33/04 ,  C08L51/06

CPC分类号： C08L33/08 ,  C08L23/06 ,  C08L27/06 ,  C08L33/10 ,  C08L55/02 ,  C08L25/14 ,  C08L33/06 ,  C08L51/003

摘要： A delustered thermoplastic resin composition which comprises 100 parts by weight of a thermoplastic resin (B); and 0.1 to 40 parts by weight of a resin (A) which essentially consists of:80 to 20 parts by weight of a polymer or a copolymer component (I) obtained by polymerizing;(a) 30 to 100% by weight of at least one monomer selected from the group consisting of an alkyl methacrylate in which the alkyl group has 1 to 4 carbon atoms and an aromatic vinyl compound;(b) 0 to 70% by weight of an alkyl acrylate in which the alkyl group has 1 to 13 carbon atoms;(c) 0 to 50% by weight of a monoethylenically unsaturated monomer other than those of (a) and (b); and(d) 0 to 5 parts by weight of a crosslinking monomer per 100 parts by weight of the total amount of the above components (a), (b), and (c); and 20 to 80 parts by weight of a copolymer component (II) obtained by polymerizing;(e) 30 to 90% by weight of an aromatic vinyl compound;(f) 10 to 60% by weight of at least one alkyl acrylate monomer in which the alkyl group has 1 to 13 carbon atoms;(g) 0 to 20% by weight of a monoethylenically unsaturated monomer other than those of (e) and (f); and(h) 0.05 to 10 parts by weight of a crosslinking monomer per 100 parts by weight of the total amount of the above components (e), (f) and (g).

摘要翻译： 一种消光热塑性树脂组合物，其包含100重量份的热塑性树脂（B）; 和0.1〜40重量份的树脂（A），其基本上由以下组成：通过聚合得到的聚合物或共聚物成分（I）为80〜20重量份; （a）30〜100重量％的至少一种选自甲基丙烯酸烷基酯中具有1〜4个碳原子的烷基和芳香族乙烯基化合物的单体; （b）0〜70重量％的烷基具有1〜13个碳原子的丙烯酸烷基酯; （c）0至50重量％的除（a）和（b）之外的单烯属不饱和单体; 和（d）每100重量份上述组分（a），（b）和（c）的总量为0-5重量份的交联单体; 和20〜80重量份通过聚合得到的共聚物组分（II）; （e）30〜90重量％的芳族乙烯基化合物; （f）10至60重量％的至少一种烷基丙烯酸酯单体，其中烷基具有1至13个碳原子; （g）除（e）和（f）以外的单烯属不饱和单体0〜20重量％ （e），（f）和（g）的总量相对于100重量份的交联单体为0.05〜10重量份。

公开(公告)号：US4508875A

公开(公告)日：1985-04-02

申请号：US526546

申请日：1983-08-26

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

IPC分类号： C08F265/04 ,  C08F285/00 ,  C08F265/06

CPC分类号： C08F265/04 ,  C08F285/00 ,  C08L33/10 ,  C08L67/00 ,  C08L69/00 ,  C08L77/00 ,  C08F220/14 ,  C08L51/06 ,  Y10S525/902

摘要： A multi-layer structure polymer composition having a gel content of at least 50% which is constituted of an innermost layer polymer (A) consisting mainly of alkyl acrylate and having a degree of swelling of 10 or lower, and having a glass transition temperature lower than 10.degree. C., a crosslinked elastomer polymer (B) consisting mainly of alkyl acrylate and having a degree of swelling slightly higher than that of said polymer (A) and having a glass transition temperature not higher than 0.degree. C., said innermost layer polymer (A) and said crosslinked elastomer polymer (B) constituting a double layer elastomer structure polymer, as well as an outermost layer polymer (C) consisting mainly of alkyl methacrylate and having a glass transition temperature not lower than 60.degree. C., and at least one intermediate layer (D) existing between said polymer (B) layer and said polymer (C) layer, the amount of alkyl acrylate in said intermediate layer (D) linearly decreasing from said polymer (B) layer to said polymer (C) layer. Said polymer composition does not readily show the phenomenon of whitening even if dipped in hot water or boiling water and is excellent in weather resistance, solvent resistance, stress-whitening resistance, water-whitening resistance and transparency.

摘要翻译： 一种凝胶含量为至少50％的多层结构聚合物组合物，其由主要由丙烯酸烷基酯组成并具有10或更低的膨胀度并且玻璃化转变温度较低的最内层聚合物（A） 所述最内层的玻璃化转变温度不高于10℃的交联弹性体聚合物（B），其主要由丙烯酸烷基酯组成，其膨胀度略高于所述聚合物（A） 层叠聚合物（A）和构成双层弹性体结构聚合物的所述交联弹性体聚合物（B）以及主要由甲基丙烯酸烷基酯组成并且玻璃化转变温度不低于60℃的最外层聚合物（C） 和存在于所述聚合物（B）层和所述聚合物（C）层之间的至少一个中间层（D），所述中间层（D）中的丙烯酸烷基酯的量从所述聚合物（B）层线性减小 到所述聚合物（C）层。 所述聚合物组合物即使浸渍在热水或沸水中也不容易显示白化现象，并且耐候性，耐溶剂性，耐应力白化性，耐水白色性和透明性优异。

公开(公告)号：US4464513A

公开(公告)日：1984-08-07

申请号：US400619

申请日：1982-07-22

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

IPC分类号： C08L25/00 ,  C08L1/00 ,  C08L7/00 ,  C08L21/00 ,  C08L23/00 ,  C08L23/06 ,  C08L25/04 ,  C08L25/14 ,  C08L27/00 ,  C08L27/06 ,  C08L33/00 ,  C08L33/02 ,  C08L33/06 ,  C08L51/00 ,  C08L51/02 ,  C08L51/04 ,  C08L55/02 ,  C08L67/00 ,  C08L75/04 ,  C08L77/00 ,  C08L101/00

CPC分类号： C08L55/02 ,  C08L101/00 ,  C08L23/06 ,  C08L25/04 ,  C08L27/06 ,  C08L33/06 ,  C08L51/04 ,  C08L75/04 ,  C08L2205/02 ,  C08L2205/22

摘要： A delustered thermoplastic resin composition obtained by incorporating in 100 parts by weight of a thermoplastic resin up to 40 parts by weight of a cross-linked polymer having an average particle diameter of 35-500.mu. which polymer is obtained by suspension-polymerizing a non-crosslinking monomer composition comprising 50-70 wt. % of a vinyl aromatic monomer, 10-40 wt. % of at least one monomer selected from the group consisting of alkyl acrylates having 1-13 carbon atoms in the alkyl group, 10-40 wt. % of a monomer selected from alkyl methacrylates having 1-4 carbon atoms in the alkyl group and 0-40 wt. % of another monoethylenically unsaturated monomer with 0.5-5 parts by weight, per 100 parts by weight of the non-cross-linking monomer composition, of a cross-linking monomer having at least two double bonds in the molecule.

摘要翻译： 一种消光热塑性树脂组合物，其通过在100重量份的热塑性树脂中加入最多40重量份的平均粒径为35-500μm的交联聚合物，该聚合物通过将非聚合物悬浮聚合而获得， 交联单体组合物，其包含50-70wt。 ％的乙烯基芳族单体，10-40wt。 ％的至少一种选自烷基中具有1-13个碳原子的丙烯酸烷基酯的单体，10-40wt。 选自烷基中具有1-4个碳原子的甲基丙烯酸烷基酯的单体的％和0-40重量％ ％的另一种单烯属不饱和单体，相对于每100重量份的非交联单体组合物，分子中具有至少两个双键的交联单体为0.5-5重量份。

公开(公告)号：US4452941A

公开(公告)日：1984-06-05

申请号：US500571

申请日：1983-06-02

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Masahiro Sugimori

IPC分类号： C08F265/06 ,  C08F285/00 ,  C08L51/00 ,  C08L51/06

CPC分类号： C08F285/00 ,  C08F265/06 ,  C08L51/003

摘要： A novel acrylic thermoplastic resin composition, transparent and excellent in flexibility, consisting of at least two different multi-layer structure polymers. Polymer [I] contains an inner layer of crosslinked acrylic elastomer and an outer layer of acrylic resin, wherein the amount of elastomeric inner layer is minor in comparison with the amount of the resin outer layer; polymer [II] has the same fundamental polymer structure as multi-layer structure polymer [I] except that the amount of crosslinked elastomer inner layer is a major amount as compared to the amount of resin outer layer. It is preferred that an intermediate layer having an intermediate property exist between the inner and outer layers of the multi-layer structure polymers.

摘要翻译： 一种由至少两种不同的多层结构聚合物组成的透明且柔软性优异的丙烯酸类热塑性树脂组合物。 聚合物[I]含有交联的丙烯酸弹性体的内层和丙烯酸树脂的外层，其中弹性体内层的量与树脂外层的量相比较小; 聚合物[II]与多层结构聚合物[I]具有相同的基本聚合物结构，除了与树脂外层的量相比，交联的弹性体内层的量是主要量。 优选在多层结构聚合物的内层和外层之间存在具有中等特性的中间层。

公开(公告)号：US4518472A

公开(公告)日：1985-05-21

申请号：US525895

申请日：1983-08-24

申请人： Kazuo Kishida ,  Isao Sasaki ,  Kenji Kushi ,  Masahiro Sugimori

发明人： Kazuo Kishida ,  Isao Sasaki ,  Kenji Kushi ,  Masahiro Sugimori

IPC分类号： C08F2/48 ,  C08F285/00 ,  C08J7/04 ,  C09D4/06 ,  C08F220/00 ,  C09D3/00

CPC分类号： C08J7/047 ,  C08F285/00 ,  C09D4/06 ,  C08J2333/06 ,  C08J2433/00

摘要： A coating composition curable by an activation energy ray, which comprises (a) 100 parts by weight of a monomer mixture (A) comprising at least 30% by weight of a compound having at least 3 acryloyloxy and/or methacryloyloxy groups in the molecule and up to 70% by weight of a compound having 1 to 2 .alpha.,.beta.-ethylenically unsaturated bonds in the molecule, (b) 0.01 to 6.0 parts by weight of at least one photosensitizer and (c) 0.5 to 30 parts by weight of an emulsion type crosslinked polymer or copolymer of a reactive monomer having one .alpha.,.beta.-ethylenically unsaturated bond in the molecule and a reactive monomer having at least two .alpha.,.beta.-ethylenically unsaturated bonds in the molecule.

摘要翻译： 一种由活化能射线固化的涂料组合物，其包含（a）100重量份的包含至少30重量％的分子中具有至少3个丙烯酰氧基和/或甲基丙烯酰氧基的化合物的单体混合物（A），和 至多70重量％的分子中具有1至2个α，β-烯属不饱和键的化合物，（b）0.01至6.0重量份的至少一种光敏剂和（c）0.5至30重量份的 分子中具有一个α，β-烯属不饱和键的反应性单体的乳液型交联聚合物或共聚物，以及在分子中具有至少两个α，β-烯属不饱和键的反应性单体。

公开(公告)号：US4528330A

公开(公告)日：1985-07-09

申请号：US438264

申请日：1982-11-01

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi ,  Hiroshi Kawasaki ,  Hiroshi Mizukoshi

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi ,  Hiroshi Kawasaki ,  Hiroshi Mizukoshi

IPC分类号： C08F285/00 ,  C08L7/00 ,  C08L21/00 ,  C08L33/00 ,  C08L33/02 ,  C08L33/04 ,  C08L33/06 ,  C08L51/00 ,  C08L51/02 ,  C08L51/06

CPC分类号： C08L33/06 ,  C08F285/00 ,  C08L51/003 ,  C08L51/00 ,  Y10S525/902

摘要： Disclosed is a resin composition which is usable for an exterior article without being coated on its surface when molded into the article and is excellent in the color tone and has good impact resistance and weatherability, said composition comprising (I) 10 to 70% by weight of a high-rubber-content graft polymer obtained by polymerizing 50 to 10% by weight of a monomer mixture (C) comprising 10 to 90% by weight of at least one aromatic vinyl monomer and 90 to 10% by weight of at least one ethylenically unsaturated monomer represented by the following general formula:CH.sub.2 .dbd.CRXwherein R stands for a hydrogen atom or methyl group, and X stands for a group --CN or --COOR.sub.1 in which R.sub.1 stands for an alkyl group having 1 to 8 carbon atoms,in the presence of a latex of a multi-layer crosslinked acrylic rubber particles containing 5 to 30% by weight of a rigid crosslinked resin (A) having a core particle size of 0.15 to 0.45.mu. in the interior of the rubber particles and 45 to 85% by weight of a crosslinked acrylic acid ester polymer (B) comprising an acrylic acid ester as the main component in the outer layer of the rubber particles, so that the total amount of the components (A), (B) and (C) is 100% by weight, (II) 90 to 30% by weight of a thermoplastic resin obtained by polymerizing at least one alkyl acrylate or methacrylate represented by the following general formula:CH.sub.2 .dbd.CRCOOR.sub.1wherein R stands for a hydrogen atom or methyl group, and R.sub.1 stands for an alkyl group having 1 to 8 carbon atoms,in an amount of at least 90% by weight, and (III) 0 to 50% by weight of a diene type rubber-containing thermoplastic resin, the sum of the amounts of the components (I), (II) and (III) being 100% by weight.

公开(公告)号：US4052482A

公开(公告)日：1977-10-04

申请号：US634284

申请日：1975-11-21

申请人： Fumio Ide ,  Kazuo Kishida ,  Akira Hasegawa

发明人： Fumio Ide ,  Kazuo Kishida ,  Akira Hasegawa

IPC分类号： C08L27/06 ,  C08L51/00 ,  C08L31/02

CPC分类号： C08L27/06 ,  C08L51/003

摘要： A thermoplastic vinyl chloride polymer composition superior in processing properties is provided. The composition comprises (I) a predominant amount of polyvinyl chloride or a copolymer predominantly comprised of vinyl chloride and (II) a minor amount of two stage sequentially produced methyl methacrylate composite polymer consisting essentially of1 to 49 wt. % of component A polymerized from a monomer or monomer mixture of 90 to 100 wt. % of methyl methacrylate and 0 to 10 wt. % of at least one copolymerizable unsaturated monomer, said component A having a glass transition temperature of at least 75.degree. C and a reduced viscosity of 1.8 to approximately 10; and51 to 99 wt. % of component B polymerized onto or in the presence of said component A from a monomer mixture of 55 to 90 wt. % of a methyl methacrylate, 10 to 45 wt. % of an acrylic acid ester and 0 to 20 wt. % of at least one unsaturated monomer copolymerizable with methyl methacrylate and the acrylic acid ester, said component B exhibiting, if polymerized in the absence of said component A, a glass transition temperature of 25.degree. to 80.degree. C and a reduced viscosity of 1.8 to 10.

公开(公告)号：US4526929A

公开(公告)日：1985-07-02

申请号：US284668

申请日：1981-07-20

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi ,  Hiroshi Kawasaki ,  Hiroshi Mizukoshi

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi ,  Hiroshi Kawasaki ,  Hiroshi Mizukoshi

IPC分类号： C08F285/00 ,  C08L7/00 ,  C08L21/00 ,  C08L33/00 ,  C08L33/02 ,  C08L33/04 ,  C08L33/06 ,  C08L51/00 ,  C08L51/02 ,  C08L51/06 ,  C08L31/02 ,  C08L33/08 ,  C08L33/10 ,  C08L51/08

CPC分类号： C08L33/06 ,  C08F285/00 ,  C08L51/003 ,  C08L51/00 ,  Y10S525/902

摘要： Disclosed is a resin composition which is usable for an exterior article without being coated on its surface when molded into the article and is excellent in the color tone and has good impact resistance and weatherability, said composition comprising (I) 10 to 70% by weight of a high-rubber-content graft polymer obtained by polymerizing 50 to 10% by weight of a monomer mixture (C) comprising 10 to 90% by weight of at least one aromatic vinyl monomer and 90 to 10% by weight of at least one ethylenically unsaturated monomer represented by the following general formula:CH.sub.2 .dbd.CRXwherein R stands for a hydrogen atom or methyl group, and X stands for a group --CN or --COOR.sub.1 in which R.sub.1 stands for an alkyl group having 1 to 8 carbon atoms, in the presence of a latex of a multi-layer crosslinked acrylic rubber particles containing 5 to 30% by weight of a rigid crosslinked resin (A) having a core particle size of 0.15 to 0.40.mu. in the interior of the rubber particles and 45 to 85% by weight of a crosslinked acrylic acid ester polymer (B) comprising an acrylic acid ester as the main component in the outer layer of the rubber particles, so that the total amount of the components (A), (B) and (C) is 100% by weight, (II) 90 to 30% by weight of a thermoplastic resin obtained by polymerizing at least one alkyl acrylate or methacrylate represented by the following general formula:CH.sub.2 .dbd.CRCOOR.sub.1wherein R stands for a hydrogen atom or methyl group, and R.sub.1 stands for an alkyl group having 1 to 8 carbon atoms, in an amount of at least 90% by weight, and (III) 0 to 50% by weight of a diene type rubber-containing thermoplastic resin, the sum of the amounts of the components (I), (II) and (III) being 100% by weight.

摘要翻译： 公开了一种树脂组合物，其可以用于外部制品而不被模制在制品中的表面上，并且色调优异并且具有良好的耐冲击性和耐候性，所述组合物包含（I）10至70重量％ 通过聚合50至10重量％的包含10至90重量％的至少一种芳族乙烯基单体和90至10重量％的至少一种的单体混合物（C）而获得的高橡胶含量的接枝聚合物 由以下通式表示的烯键式不饱和单体：CH 2 = CRX其中R代表氢原子或甲基，X代表基团-CN或-COOR1，其中R1代表具有1至8个碳原子的烷基， 在含有5〜30重量％的在橡胶粒子内部具有0.15〜0.40μm核心粒径的刚性交联树脂（A）的多层交联丙烯酸橡胶粒子的乳胶的存在下，在45〜 85重量％ （A），（B）和（C）成分的总量为100质量％的由丙烯酸酯作为主要成分的交联丙烯酸酯系聚合物（B） 重量，（II）90〜30重量％的通过聚合至少一种由以下通式表示的丙烯酸烷基酯或甲基丙烯酸烷基酯得到的热塑性树脂：CH2 = CRCOOR1其中R代表氢原子或甲基，R1代表 碳原子数为1〜8的烷基，至少90重量％，（III）0〜50重量％的含二烯系橡胶的热塑性树脂，成分的总量（ I），（II）和（III）为100重量％。

公开(公告)号：US4351921A

公开(公告)日：1982-09-28

申请号：US221359

申请日：1980-12-29

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Yasunori Kawachi

IPC分类号： C08L51/00 ,  C08F285/00 ,  C08L7/00 ,  C08L21/00 ,  C08L25/00 ,  C08L33/00 ,  C08L33/02 ,  C08L51/02 ,  C08L51/04 ,  C08L51/06 ,  C08L55/00 ,  C08L55/02 ,  C08L33/08 ,  C08L33/12

CPC分类号： C08F285/00 ,  C08L51/04

摘要： A resin composition for use in uncoated exterior materials markedly excellent in appearance and having high impact resistance and weather resistance wherein 10-70% by weight of a graft copolymer (I) having a high rubber content, 90-30% by weight of a rigid thermoplastic resin (II) comprising 10-90% by weight of at least one aromatic vinyl monomer and 90-10% by weight of at least one ethylenic unsaturated monomer having the following general formula:CH.sub.2 =CRXwherein R represents hydrogen or CH.sub.3 group and X represents CN or COOR.sub.1 group (R.sub.1 represents alkyl group having 1-8 carbon atoms), and 0-50% by weight of a diene rubber-containing thermoplastic resin (III) are blended together so that the total amount of components (I) through (III) is 100% by weight, said graft copolymer (I) having a high rubber content being obtained by polymerizing 50-10% by weight of a monomer mixture (c) comprising 10-90% by weight of at least one aromatic vinyl monomer and 90-10% by weight of at least one ethylenic monomer having the following general formula:CH.sub.2 =CRXwherein R represents hydrogen or CH.sub.3 group and X represents CN or COOR.sub.1 group (R.sub.1 represents alkyl group having 1-8 carbon atoms) in the presence of a latex of a crosslinked acrylic rubber having a multi-layer structure which contains, in its particle, 5-30% by weight of a rigid crosslinked resin (a) having a core particle diameter of 0.25-0.40.mu. and of which outer layer part is constructed of 45-85% by weight of a crosslinked acrylic ester type polymer (b) constituted mainly of an acrylic ester, so that the total amount of components (a) through (c) is 100% by weight.

摘要翻译： 一种用于未涂覆的外观材料的树脂组合物，其外观显着优异且具有高抗冲击性和耐候性，其中10-70重量％的具有高橡胶含量的接枝共聚物（I），90-30重量％的刚性 包含10-90重量％的至少一种芳族乙烯基单体和90-10重量％的具有以下通式的至少一种烯属不饱和单体的热塑性树脂（II）：CH 2 = CRX其中R表示氢或CH 3基团， X表示CN或COOR1基团（R1表示具有1-8个碳原子的烷基）和0-50重量％的含二烯橡胶的热塑性树脂（III），使得组分（I）的总量 通过（III）为100重量％，所述接枝共聚物（I）具有高橡胶含量，其通过聚合50-10重量％的单体混合物（c）获得，所述单体混合物（c）包含10-90重量％的至少一种芳族 乙烯基单体和90-10重量％的至少一种乙烯 具有以下通式的酸性单体：其中R表示氢或CH3组，X表示CN或COOR1基团（R1表示具有1-8个碳原子的烷基）在具有交联丙烯酸橡胶的胶乳的存在下， 多层结构，其颗粒中含有5-30重量％的核心粒径为0.25-0.40μm的刚性交联树脂（a），其外层部分由45-85重量％构成 的主要由丙烯酸酯构成的交联丙烯酸酯类聚合物（b），使得成分（a）〜（c）的总量为100重量％。

公开(公告)号：US4173600A

公开(公告)日：1979-11-06

申请号：US963733

申请日：1978-11-27

申请人： Kazuo Kishida ,  Akira Hasegawa ,  Hiroshi Mohri

发明人： Kazuo Kishida ,  Akira Hasegawa ,  Hiroshi Mohri

IPC分类号： C08F257/02 ,  C08F285/00 ,  C08F279/02

CPC分类号： C08F257/02 ,  C08F285/00 ,  Y10T428/31924

摘要： A multi-stage sequentially produced polymer structure composition, comprising: an innermost layer (A), and successively seed polymerized thereupon an elastic polymer layer (B), an outermost layer (C) and at least one intermediate layer (D), said layer (A) which has a glass transition temperature (Tg) of at least 10.degree. C. and which constitutes 5-35% by weight of the total polymer composition being the polymerized product of a monomer mixture comprising 51-100 parts by weight of styrene or a styrene derivative, 0-49 parts by weight of a monomer having a copolymerizable double bond, 0-10 parts by weight of a polyfunctional monomer, and 0-5 parts by weight of a graft crosslinking agent; said layer (B) which has a glass transition temperature of 0.degree. C. or less and which constitutes 5-55% by weight of the total polymer composition being the product, polymerized in the presence of a product containing the previously polymerized stages, of a monomer mixture comprising 60-100 parts by weight of a diene monomer, 0-40 parts by weight of a monomer having a copolymerizable double bond, 0-10 parts by weight of a polyfunctional monomer and 0-5 parts by weight of a graft crosslinking agent; said layer (C) which has a glass transition temperature of at least 50.degree. C. and which constitutes 10-70% by weight of the total polymer composition being the product, polymerized in the presence of a product containing the previously polymerized stages, of a monomer mixture comprising 51-100 parts by weight of styrene or a styrene derivative and 0-49 parts by weight of a monomer having a copolymerizable double bond; and said intermediate layer (D) which constitutes 5-45% by weight of the total polymer composition being the product, polymerized in the presence of a product containing the previously polymerized stages, of a monomer mixture comprising 20 to (Y-10) parts by weight of styrene or a styrene derivative, (Y-10) to 20 parts by weight of a diene monomer, 0-10 parts by weight of a polyfunctional monomer and 0-5 parts by weight of a graft crosslinking agent, wherein Y is the amount of diene monomer used in the formation of said layer (B).