PROCESS FOR PRODUCING POLYOLEFIN

摘要

A polyolefin is producing by polymerizing ethylene or copolymerizing ethylene and the other alpha -olefin at 50 to 100 DEG C in a hydrocarbon solvent in the presence of a catalyst system of an organoaluminium compound and a transition metal compound component which is a solid catalytic component containing a magnesium compound and a titanium compound under the condition (a) two step polymerizations of a first polymerization step and a second polymerization step in the presence of a reaction mixture obtained by said first polymerization step; (b) a polymerization in the presence of hydrogen at a molar ratio of H2 to C2H4 (vapor phase) of 0.01-0.8 to produce a polymer A having a viscosity average molecular weight of 2 x 10<5>-7x10<5> at a ratio of 30 to 70 wt.% based on the total polymer in one of said first or second polymerization step and a polymerization in the presence of hydrogen at a molar ratio of H2 to C2H4 (vapor phase) of 1.5-15 to produce a polymer B having a viscosity average molecular weight of 1 x 10<4>-4 x 10<4> at a ratio of 70 to 30 wt.% based on the total polymer in the other polymerization step to give a ratio of a viscosity average molecular weight of polymer A to a viscosity average molecular weight of polymer B of 15 to 55; (c) said production of said polymer A as a copolymer of ethylene and other alpha -olefin and said production of said polymer B as a homopolymer of ethylene or a copolymer of ethylene and the other alpha -olefin; and (d) said production of the total polymer as a polymer having a melt index of less than 0.5 g/10 min.