.alpha.-olefin polymerization catalyst component

Abstract

This invention relates to a catalytic component for the polymerization of .alpha.-olefins and provides a catalytic component of magnesium support type capable of exhibiting a high stereoregularity while maintaining an improved strength as well as a high catalytic activity. The features thereof consist in a catalyst component for the polymerization of .alpha.-olefins obtained by contacting (A) a solid component comprising, as essential components, magnesium, titanium, a halogen and an electron-donating compound with (D) an olefin in the presence of (B) a trialkylaluminum and (C) a dimethoxy group-containing compound represented by the general formula R.sup.1 R.sup.2 Si(OCH.sub.3).sub.2 where R.sup.1 and R.sup.2 are, same or different, aliphatic hydrocarbon groups with 1 to 10 carbon atoms and having a volume, calculated by the quantum chemistry calculation, of 230 to 500 .ANG..sup.3 and an electron density of oxygen atoms in the methoxy group, calculated similarly, ranging from 0.685 to 0.800 A. U. (atomic unit) and a catalyst component for the polymerization of .alpha.-olefins obtained by contacting (A) a solid component comprising, as essential components, a metal oxide, magnesium, titanium, a halogen and an electron-donating compound with (D) an olefin in the presence of (B) a trialkylaluminum and (C) a dimethoxy group-containing compound represented by the general formula R.sup.1 R.sup.2 Si(OCH.sub.3).sub.2 where R.sup.1 and R.sup.2 are, same or different, aliphatic hydrocarbon groups with 1 to 10 carbon atoms and having a volume calculated by the quantum chemistry calculation, of 170 to 500 .ANG..sup.3 and an electron density of oxygen atoms in the methoxy group, calculated similarly, ranging from 0.690 to 0.800 A. U. (atomic unit) or the volume in the range of 200 to 500 .ANG..sup.3 and the electron density in the range of 0.685 to 0.800 A. U.

Dependencies are inferred from the claim text.