Patent ID: 7166677
Filing Date: 2007-01-23
Classification: C08F,C08L

Abstract:
1. A polypropylene resin composition comprising: (A) (a-1) a crystalline propylene/ethylene block copolymer or (a-3) a polymer mixture comprising (a-1) the crystalline propylene/ethylene block copolymer and (a-2) a crystalline propylene homopolymer, in an amount of 5 to 56% by weight, (B) a hydroxyl group-containing polypropylene in an amount of 10 to 45% by weight, (C) a copolymer rubber of ethylene and an α-olefin, in an amount of 18 to 25% by weight, (D) a hydrogenation product of a block copolymer containing a polymer block of a monovinyl-substituted aromatic hydrocarbon compound and a polymer block of a conjugated diene compound, in an amount of 1 to 10% by weight, and (E) an inorganic filler in an amount of 15 to 25% by weight, the total amount of said components (A), (B), (C), (D) and (E) being 100% by weight, wherein: the crystalline propylene/ethylene block copolymer (a-1) comprises a propylene homopolymer portion and a propylene/ethylene random copolymer portion and has a melt flow rate (ASTM D-1238, 230° C., load of 2160 g) of 70 to 130 g/10 min, said propylene homopolymer portion having an isotactic pentad fraction (mmmm fraction), as measured by the crystalline propylene homopolymer (a-2) has an isotactic pentad fraction (mmmm fraction) of not less than 97% by weight and a melt flow rate (ASTM D-1238, 230° C., load of 2160 g) of 100 to 300 g/10 min, the polymer mixture (a-3) comprises 50 to 99% by weight of the crystalline propylene/ethylene block copolymer (a-1) and 1 to 50% by weight of the crystalline propylene homopolymer (a-2), the total amount of said components (a-1) and (a-2) being 100% by weight, the hydroxyl group-containing polypropylene (B) has an intrinsic viscosity [η], as measured in decalin at 135° C., of 0.8 to 2.0 dl/g and a melting point, as detected by a differential scanning calorimeter, of 150 to 168° C., the copolymer rubber (C) has a melt flow rate (ASTM D-1238, 230° C., load of 2160 g) of 0.5 to 15 g/10 min, and hydroxyl group-containing monomer units derived from the hydroxyl group-containing polypropylene (B) are contained in amounts of 1.3 to 4.0% by weight in 100% by weight of the polypropylene resin composition.