Patent ID: 7396892
Filing Date: 2008-07-08
Classification: B01J,C08F,C08L,Y10S

Abstract:
1. An interstitially mixed, multimodal polyethylene copolymer containing a low molecular weight portion comprising a copolymer of ethylene and at least one other copolymerizable olefin monomer, and a higher molecular weight portion comprising a polyethylene homo- or copolymer, prepared by the process of a) polymerizing at least two olefin monomers in the presence of hydrogen in a prior slurry reactor employing light solvent as a slurry medium to form a first polyolefin polymer of a first molecular weight; and b) removing said first polyolefin polymer from said prior slurry reactor as a hydrogen-containing polymer slurry in light solvent and introducing said hydrogen-containing polymer slurry into a subsequent slurry reactor containing ethylene and optionally one or more olefin monomers other than ethylene, and employing a low concentration of hydrogen, polymerizing to form an ethylene homo- or copolymer, and recovering a polyolefin polymer therefrom, wherein the hydrogen concentration in the hydrogen-containing polymer slurry is lower than the hydrogen concentration in said prior slurry reactor, the hydrogen mass flow from the hydrogen-containing polymer slurry fed to the subsequent reactor is less than a fresh hydrogen mass flow feed to the subsequent reactor by a factor of at least 10, and wherein a rapidly hydrogen-consuming catalyst is not employed in said subsequent slurry reactor.