Abstract: An acetal resin composition comprising (A) an acetal resin and (B) 1 to 200 parts by weight, per 100 parts by weight of the acetal resin (A), of at least one modified alpha-olefin polymer, said modified alpha-olefin polymer (B) being a graft-copolymerization product of 100 parts by weight of an alpha-olefin polymer and 0.01 to 10 parts by weight of an unsaturated carboxylic acid or its derivative.

Abstract: An improved process for preparing an impact-resistant chemically blended propylene polymer or copolymer, which comprises the following three steps:(1) a first step of polymerizing propylene containing 0 to 1 mole% of another olefin in the presence of a catalyst composed of (a) a carrier-supported titanium catalyst component containing at least magnesium, halogen and titanium on the surface of the carrier and (b) an organo aluminum compound to form specific crystalline polypropylene;(2) a second step of copolymerizing propylene and ethylene in the presence of the reaction product of the first step and the same catalyst while maintaining the content of propylene in the gaseous phase of the polymerization zone at 65 to 90 mole% thereby to form specific low-crystalline propylene/ethylene copolymer; and(3) a third step of polymerizing ethlene, or both ethylene and propylene in the presence of the reaction product of the second step and the same catalyst while maintaining the content of propylene in the gaseous pha