Patent ID: 6545099
Filing Date: 2003-04-08
Classification: C08F

Abstract:
A process for preparing a propylene block copolymer, which comprises a first polymerization stage for homopolymerizing propylene or copolymerizing propylene with ethylene and/or &agr;-olefin of 4 to 10 carbon atoms to prepare a crystalline polymer and a second polymerization stage for copolymerizing two or more monomers selected from &agr;-olefin of 2 to 20 carbon atoms to prepare a low-crystalline or non-crystalline copolymer, 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) wherein each of R and R is a hydrocarbon group, and n is a number satisfying the condition of 0H2C&boxH;CHâ€”Xâ€ƒâ€ƒ(i) H2C&boxH;CHâ€”CH2â€”Xâ€ƒâ€ƒ(ii) wherein X is a cycloalkyl group, an aryl group or M 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) wherein, n is 1, 2 or 3; when n is 1, Ra is a secondary or a tertiary hydrocarbon group; when n is 2 or 3, at least one of Ra is a secondary 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.