PROCESS FOR PRODUCING PROPYLENE-ETHYLENE BLOCK COPOLYMER

摘要

A propylene-ethylene block copolymer is produced in the presence of a catalytic system essentially comprising an organoaluminum compound and a solid titanium trichloride catalytic complex having an atomic ratio of Al to Ti of less than 0.15 and having a complexing agent in two stages of polymerization; (a) a first stage for polymerizing propylene in the presence of a liquid propylene and hydrogen to produce a propylene homopolymer having a melt flow index of 1 to 150 at a ratio of 70 to 95% by weight based on a total of polymers; and (b) a second stage for copolymerizing propylene and ethylene in the presence of hydrogen and a liquid propylene at a concentration of propylene in vapor phase based on a total of propylene and ethylene in vapor phase of 50 to 85 mol. % and at a concentration of hydrogen in vapor phase based on a total of propylene and ethylene in vapor phase of 0.5 to 30 mol %, to produce ethylene-propylene copolymer having a melt flow index of 10-7 to 0.1 at a ratio of 5 to 30% by weight based on a total of polymers.