GB1015894A - Novel catalyst system and olefin polymerization therewith - Google Patents

Abstract

A catalyst composition for the polymerization of alpha-olefins is made by mixing in an inert reaction medium (1) an alkyl aluminium dihalide or an alkyl aluminium sesquihalide; (2) an alkoxy silane of the formula R1R2R3R4Si, in which R1 is an alkoxy radical, and R2, R3 and R4 are selected from alkoxy and hydrocarbon radicals; and (3) a TiCl3 selected from (a) TiCl3 cocrystallized with AlCl3 and prepared by the reduction of TiCl4 with Al, and ball or rod milled, until as determined by X-ray diffraction it possesses less than 30% of its original crystalline structure; (b) the precipitate obtained by reacting TiCl4 with an alkyl aluminium chloride; and (c), type (b) which has been ball or rod milled. The polymerization is preferably effected in an inert hydrocarbon solvent. The alpha-olefin may be propylene, butene-1, or 4-methyl pentene. Component (2) of the catalyst may be trimethylethoxysilane, diethyldiethoxysilane, tetramethoxysilane, ethyl orthosilicate, or triphenylethoxysilane. The catalyst used contains the components in the following proportions, mol. ratio of alkyl aluminium compound to TiCl3 from 0.2: 1 to 10: 1, and atomic ratio of aluminium to active silane oxygen from 2: 3 to 5: 1. The polymerization may be effected in the presence of hydrogen, and the polymers recovered by conventional techniques, e.g. addition of methanol. The polymer were fractionated into pentane or hexane insoluble portions.