Polypropylene based resin composition containing an ethylene-octene copolymer rubber

摘要

A polypropylene based resin composition (I) comprises (A) 55-75 wt.% of a crystalline polypropylene based resin comprising (A1) a crystalline propylene-ethylene block copolymer consisting of a propylene homopolymer segment and a random propylene-ethylene copolymer segment or (A2) a mixture of (A1) and a crystalline propylene homopolymer, (B) 10-15 wt.% of an ethylene-octene copolymer rubber having a melt index (JIS K 6758) of 0.5-10 g/10 min at 190 deg C; an octene content of 20-25 wt.% and a density of 0.860-0.875 g/cm<3> and (C) 15-30 wt.% talc having an average particle size diameter of not more than 3 mu . (I) satisfies formulae 0.25 <= (A)<1>/(A)<1>+(B<1>) <= 0.40 (1), Y /- -0.002X + 85 (2), X /- 20,000 (3) and Y /- 15 (4), where (A)<1> = the weight of the random propylene-ethylene copolymer segment in (A1); (B<1>) = the weight of (B); X = the flexural modulus (JIS-K 7203) in kg/cm<2> at 23 deg C; Y = the Izod toughness (JIS K 7100) in kg.cm/cm at 23 deg C; and whereby the extension (ASTM D638) is not less than 150% at 23 deg C and the melt index (JIS K 6758) is 15-25 g/10 min at 230 deg C and the density is 1.00-1.14 g/cm<3>. Also claimed is an injected moulded object prepared using (I).