New Activators and Novel Activation Chemistry of Group IV Metallocenes for Olefin Polymerization: Double Activation, Dications, and Soluble Salts

摘要

Within the framework of a metallocene olefin polymerization catalyst, variation of catalyst ligand structure is generally regarded as a means of effecting catalyst efficiency and polymer architecture. Over the past decade Dow has focused its R&D effort on improving catalyst activity by this approach. Another crucial factor in developing cationic group (IV) metallocenes relates to the manner by which they are activated in the polymerization process. Activation of a dialkyl group (IV) procatalyst by varying the nature of the Lewis acid or the structure of the resulting contact ion pair can have a profound effect on catalyst efficiency and molecular weight of the resulting polyolefin, especially in a high temperature, solution based process. We will highlight some of our recent discoveries in metallocene activation chemistry wherein catalyst efficiency can be enhanced by 10-30X over standard activation protocols.