High-Temperature Ethylene/#alpha#-Olefin Copolymeriation with a Zirconocene Catalyst: Effects of te Zirconocene Ligand and Polymerization Conditions on Coplymerizaiton Behavior

摘要

Copolymerizations of ethylene and #alpha#-olefin with various zirconocene compounds at a high temperature were carried out to study the relationship between the ligand structuer of zirconocene compounds and the copolymerization behavior. All of the indenyl-base dzirconocene compounds in combination with dimethylanilinium tetrakis(pentafluorophenyl)borate/triisobutylaluminum produced only low moleuclar weight copolymers at a high temperature, regardless of the substitutents and bridged structures of the zirconocene compounds. However, zirconocene compounds with a fluorenyl ligand agve rise to a signiicant increase in the activity and moleuclar weight of the copolymers by the selectioin of a diphenylmethylene bridge structure even at a high temperature. Ethylene/1-hexene copolymers obtaied with the fluorenyl-based cartalysts contained inner double bonds accompanied by the generation of hydrogen, presumably because of a C-H bond activation mechanism. The contents of theinner double bonds were significantly influenced by the polymerizaton conditoins, including the 1-hexene feed content, polymerization temperature, and ethylene pressure.