Abstract: A catalyst system for use in olefinic polymerization and copolymerization is comprised of components (A), (B) and (C). The catalyst component (A) consisting essentially of titanium, magnesium, halogen, polycarboxylic acid esters and organic phosphorus compounds is a solid product, being prepared by mixing titanium tetrahalide and auxiilary precipitant with a homogeneous solution of magnesium halide in a solvent system consisting essentially of an organic epoxy compound and an organic phosphorus compound to form a solid product which is then treated with a polycarboxylic acid ester and titanium tetrahalide. Component (B) is an organic aluminum compound, and component (C) is an organic silicon compound. The catalyst system has very high activity, and the resultant polymers have very high stereospecificity and good granular appearance.

Abstract: A catalyst system for use in olefinic polymerization and copolymerization is comprised of components (A), (B) and (C). The catalyst component (A) consisting essentially of titanium, magnesium, halogen, polycarboxylic acid esters and organic phosphorus compounds is a solid product, being prepared by mixing titanium tetrahalide and auxiliary precipitant with a homogeneous solution of magnesium halide in a solvent system consisting essentially of an organic epoxy compound and an organic phosphorus compound to form a solid product which is then treated with a polycarboxylic acid ester and titanium tetrahalide. Component (B) is an organic aluminum compound, and component (C) is an organic silicon compound. The catalyst system has a very high activity, and the resultant polymers have very high stereospecificity and good granular appearance.