Process for polymerizing olefins and polymerization catalyst therefor

Claim 1

An olefin polymerization catalyst formed from (A) a solid titanium component which contains magnesium, titanium, halogen and an electron donor as the essential components prepared by contacting of a magnesium compound with a titanium compound and an electron donor, said magnesium compound having been for a time in a liquid condition during preparation of said solid titanium component; (B) an organoaluminum compound; and (C) an organosilicon compound represented by the following formula SiR.sup.21 R.sup.22.sub.m (OR.sup.23).sub.3-m wherein R 21 represents a cyclopentyl group, a cyclopentyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, an alkyl group having 2 to 4 carbon atoms substituted by a cyclopentyl group or a cyclopentyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, a cyclopentenyl group, a cyclopentenyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, a cyclopentadienyl group, a cyclopentadienyl group substituted by 1 to 4 alkyl groups having 1 to 4 atoms, an indenyl group, an indenyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, an indanyl group, an indanyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, a tetrahydroindenyl group, a tetrahydroindenyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms, a fluorenyl group or a fluorenyl group substituted by 1 to 4 alkyl groups having 1 to 4 carbon atoms; R 22 and R 23 are identical or different and each represents a hydrocarbon group; and 0≦m<3.