Polypropylene resin composition

Abstract

A polypropylene resin composition comprising: (A) 45 to 70% by weight of an ethylene-propylene block copolymer synthesized under the process comprising the steps of; (a) polymerizing propylene with a Ziegler-Natta catalyst to obtain a highly crystalline polypropylene that contain not less than 97% by weight of a fraction insoluble in boiling n-heptane, and (b) copolymerizing ethylene with the polypropylene (a), and which (a) contains 0.5 to 10% by weight of ethylene, (b) contains 5 to 20% by weight of a fraction being soluble in p-xylene at room temperature and having an intrinsic viscosity value of not less than 2 (measured in decalin at 135.degree. C.), (c) has a melt-flow index value of 30 to 100 g/10 min., and, (d) has a value of flexural modulus of not less than 18,000 kg/cm.sup.2, (B) 10 to 20% by weight of an amorphous ethylene-propylene copolymer having (a) an ethylene content of 70 to 90% by weight, (b) a Mooney viscosity value (ML.sub.1+4 at 100.degree. C.) of 5 to 70, (C) 5 to 15% by weight of an ethylene-.alpha.-olefin copolymer having (a) an .alpha.-olefin content of 5 to 15% by mole, (b) a value of gravity of not more than 0.91, and (c) a melt-flow index value of 2.2 to 50 g/10 min. at 230.degree. C., (D) 1 to 10% by weight of an amorphous ethylene-butene copolymer having (a) a butene content of 10 to 25% by weight, and (b) a Mooney viscosity value (ML.sub.1+4, at 100.degree. C.) of 5 to 20, (E) not more than 15% by weight of a talc that (a) has an average diameter D50 of from 1.0 to 3.0 .mu.m, and (b) does not contain a particle having a diameter of 10 .mu.m or more, wherein the component (B) is rubber reinforced by lamellae of components (C) and (D).

Dependencies are inferred from the claim text.