Patent ID: 6630559
Filing Date: 2003-10-07
Classification: C08F

Abstract:
A process for preparing a propylene polymer having a crystallinity of not less than 60%, which comprises polymerizing propylene in the presence of a catalyst for olefin polymerization comprising:(I) a prepolymerized catalyst obtained by prepolymerizing at least one reactive monomer represented by the following formula (i) or (ii) using (a) a solid titanium catalyst component containing magnesium, titanium, halogen and an electron donor as essential components, (b) an organometallic catalyst component and an organosilicon compound represented by the following formula (c-i) RnSi(ORâ€²)4âˆ’nâ€ƒâ€ƒ(c-i) â€ƒwherein each of R and Râ€² is a hydrocarbon group, and n is a number satisfying the condition of 0>n>4, said reactive monomer being prepolymerized in an amount of 0.1 to 1,000 g per 1 g of the solid titanium catalyst component (a); H2C&boxH;CHâ€”Xâ€ƒâ€ƒ(i) H2C&boxH;CHâ€”CH2â€”Xâ€ƒâ€ƒ(ii) â€ƒwherein X is a cycloalkyl group, an aryl group or â€ƒM is carbon or silicon, R1 and R2 are each a hydrocarbon group, and R3 is hydrogen or a hydrocarbon group; (II) the organometallic catalyst component (b); and (III) a silicon compound represented by the following formula (iii) or a compound having at least two ether linkages existing via plurality of atoms: Ranâ€”Siâ€”(ORb)4âˆ’nâ€ƒâ€ƒ(iii) â€ƒwherein, n is 1, 2 or 3; when n is 1, Ra is a cyclopentyl group which may have a substituent group or a tertiary hydrocarbon group; when n is 2 or 3, at least one of Ra is the cyclopentyl group which may have a substituent group or a tertiary hydrocarbon group, Ra may be the same or different, and Rb is a hydrocarbon group of 1 to 4 carbon atoms; and when 4âˆ’n is 2 or 3, Rb may be the same or different; in said process, propylene being polymerized in an amount of 3,000 to 1,000,000 g per 1 g of the solid titanium catalyst component (a) contained in the prepolymerized catalyst.