Process for producing propylene block copolymers.

摘要

A process for producing block copolymers which comprises the steps of (a) polymerizing propylene in the presence of a catalyst to give a crystalline propylene polymer, and (b) copolymerizing ethylene and at least one kind of alpha-olefin in the presence of said catalyst and said polymer, said catalyst comprising (A) a catalyst component obtained by contacting with one another 1) a magnesium alkoxide, 2) a silicon compound having the hydrogen-silicon bond, 3) an electron donor compound, and 4) a titanium compound (B) an organic compound of a metal in Group I to III of the Periodic Table, and (C) an organosilicon compound represented by the formula RpSiXm(OR min )n, wherein R and R min are the same or different C1-20 hydrocarbon groups, X is a halogen atom, 0 </= p < 4, 0 </= m < 4, 0 < n </= 4, and p + m + n = 4.