Process for producing propylene-ethylene block copolymer.

摘要

A propylene-ethylene block copolymer in the presence of a catalyst comprises as main components, a solid titanium-containing catalytic component and an organoaluminum compound having the formula AIR1_mCl3-m (R<1> represents a C1-20 hydrocarbon moiety; and m is 3 >/= m > 1.5) by producing a homopolymer of propylene or a propylene-ethylene copolymer by polymerizing propylene or both propylene and ethylene at a vapor phase propylene concentration of 90 mol % or higher based on the sum of propylene and ethylene in a first step and producing a propylene-ethylene block copolymer by copolymerizing propylene and ethylene at a vapor phase propylene concentration of less than 90 mol % based on the sum of propylene and ethylene in the presence of the polymer resulted in the first step, and the catalyst in a second step which is characterized by newly adding an aluminum compound having the formula AIR2_nX3-n (R<2> represents a C1-20 hydrocarbon moiety; X represents a halogen atom and n is 1.5 >/= n >/= 0) to the components for the copolymerization in the second step.