Patent ID: 6384122
Filing Date: 2002-05-07
Classification: C08K,C08L

Abstract:
A thermoplastic resin composition which comprises:(1) 57 to 71% by weight of (A) a crystalline polypropylene selected from the following (i) or (ii): (i) a crystalline ethylene-propylene copolymer in which the propylene homopolymer portion which is the first segment has a Q value of 3 to 5 which is the weight average molecular weight (Mw)/number average molecular weight (Mn) ratio according to a gel permeation chromatography (GPC) method, an isotactic pentad fraction of not less than 0.98 as calculated by 13C-NMR and an intrinsic viscosity of 0.9 to 1.1 dl/g as measured at 135Â° C. in tetralin and the ethylene-propylene random copolymer portion which is the second segment has an intrinsic viscosity of 4.5 to 5.5 dl/g as measured at 135Â° C. in tetralin, an ethylene/propylene ratio of 25/75 to 35/65 (weight % ratio) and which crystalline ethylene-propylene copolymer has a melt flow index (MI) of not less than 30 g/10 minutes, (ii) a mixture of the crystalline ethylene-propylene copolymer (i) with a crystalline propylene homopolymer having a Q value of 3 to 5 according to the GPC method, an isotactic pentad fraction of not less than 0.98 as calculated by 13C-NMR and an intrinsic viscosity of 0.9 to 1.1 dl/g as measured at 135Â° C. in tetralin; (2) 14 to 18% by weight of at least one rubber component selected from the group consisting of the following (B), (C) and (D): (B) 0 to 5% by weight of the following ethylene-butene-1 copolymer rubber: an ethylene-butene-1 copolymer rubber having a Q value of not more than 2.7 according to the GPC method, a butene-1 content of 15 to 20% by weight, an intrinsic viscosity of 1.1 to 2.1 dl/g as measured at 70Â° C. in xylene and a Mooney viscosity at 100Â° C. (ML1+4 100Â° C.) of 7 to 90, (C) 0 to 5% by weight of the following ethylene propylene copolymer rubber: an ethylene-propylene copolymer rubber having a Q value of not more than 2.7 according to the GPC method, a propylene content of 20 to 30% by weight, an intrinsic viscosity of 1.8 to 2.2 dl/g as measured at 70Â° C. in xylene and a Mooney viscosity at 100Â° C. (ML1+4 100Â° C.) of 35 to 100, and (D) 10 to 18% by weight of the following vinyl aromatic compound-containing rubber: a vinyl aromatic compound-containing rubber in which a vinyl aromatic compound is bonded to an olefinic copolymer rubber or a conjugated diene rubber, and which has a vinyl aromatic compound content of 1 to 50% by weight and a melt viscosity at 230Â° C. at a shear rate of 10 secâˆ’1 of not more than 104 as measured by a capillary flow tester, and which is characterized in that in a blend prepared by adding 10% by weight of the vinyl aromatic compound-containing rubber to a crystalline propylene homopolymer having an isotactic pentad fraction of 0.98 as calculated by 13C-NMR and an intrinsic viscosity of 1.55 dl/g as measured at 135Â° C. in tetralin, the difference (&Dgr;Tg, Tg shift) between glass transition points (Tg) attributed to the crystalline propylene homopolymer portion before and after the blending is less than 3Â° C.; (3) 15 to 25% by weight of (E) talc having an average particle size of not more than 4 &mgr;m; and (4) 0 to 10% by weight of (F) fibrous magnesium oxysulfate having a fiber diameter of 0.3 to 2 &mgr;m and an average fiber length of 5 to 50 &mgr;m, and which thermoplastic resin composition satisfies the following equations 1) to 4):(A)+(B)+(C)+(D)+(E)+(F)=100â€ƒâ€ƒ1) 0.20&lE;{[(A)Ã—(A)â€²+(B)+(C)+(D)]/100}&lE;0.25â€ƒâ€ƒ2) 0.1&lE;{(A)Ã—(A)â€²/[(A)Ã—(A)â€²+(B)+(C)+(D)]}â€ƒâ€ƒ3) 15&lE;[(E)+(F)]&lE;25â€ƒâ€ƒ4) wherein (A), (B), (C), (D), (E) and (F) represent weight % of the respective components and (A)â€² represents the weight fraction of the second segment in the crystalline polypropylene (A), and has a melt flow index (JIS-K-6758, 230Â° C.) of 25 to 35 g/10 minutes and a flexural modulus at 23Â° C. of not less than 20,000 kg/cm2.