IMPACT-RESISTANT CHEMICALLY BLENDED PROPYLENE POLYMER COMPOSITION AND PROCESS FOR PREPARATION THEREOF

摘要

An improved process for preparing an impact-resistant chemically blended propylene polymeror copolymer, which comprises the following three steps: 1) a first step of polymerizing propylene containing 0 to 1 mole% of another another 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 organoaluminum compound to form specific crystalline polypropylene; (2) a second step of copolymerizing propylene and ethylene in the presence or 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 copolymers and (3) a third step of polymerizing ethlene, or both ethyleneand 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 phase of the polymerization zone at 0 to 15 mole% thereby to form specific polyethylene or ethylene/propylene copolymer.