Olefin polymerization using homogeneous catalysts under high pressures

摘要

Olefin polymerization using homogeneous catalysts under super-high pressure such as 100-1,500 MPa was studied. The catalytic activity increased under high pressure and it gave maximum at 250-500 MPa in most metallocene catalysts, while the activity of palladium and nickel catalysts monotonously increased as pressure elevated. The molecular weight of the polymers obtained at high pressure was higher than those at normal pressure, and permethylated ansa-hafnocenes produced super-high molecular weight polyhexene whose Mw was ten million. It was revealed that bimolecular chain-transfer reaction was accelerated due to high pressure in zirconium and nickel catalysts, although hafnium and palladium catalysts showed little pressure-effects in the chain-transfers.