Patent ID: 7151145

Claim:
In a two-step process wherein ethylene homopolymer is produced in a first polymerization reactor and ethylene-α-olefin copolymer is produced in a second polymerization reactor, said polymerizations conducted in an inert hydrocarbon medium using a solid high activity transition metal-containing catalyst and organoaluminum co-cocatalyst, and said homopolymer and copolymer are combined to obtain a final polyethylene resin product, to narrow the short-chain branching distribution of the ethylene-α-olefin copolymer, the improvement comprising conducting the copolymerization in the second polymerization reactor in the presence of from 1 to 100 ppm, based on the inert hydrocarbon medium, monoalkyltrialkoxysilane of the formula R 2 Si(OR 3 ) 3 where R 2 is a C 1-10 alkyl group and R 3 is a C 1-5 alkyl group while maintaining reactor conditions and feed rates to produce copolymer having a density of 0.940 g/cm 3 or less and containing 90 percent or more low short-chain branched copolymer having fewer than 10 branches per 1000 carbon atoms.