Process for production of a high molecular weight ethylene a-olefin elastomer with a metallocene alumoxane catalyst

Abstract

Abstract Disclosed is a process for preparing high molecular weight ethylene-α-olefin elastomers, preferably an ethylene-propylene elastomer, by liquid phase polymerization of the requisite monomers in the presence of a metallocene/alumoxane catalyst system. Preferably, the process is carried out as a slurry polymerization utilizing the metallocene/alumoxane catalyst in supported form on a silica gel support with the α-olefin monomer maintained in liquid state and used in excess to serve as a polymerization diluent. The metallocene component of the catalyst by which the process is practiced is of the formula: ##STR1## wherein M is zirconium, titanium or hafnium; each R 1 independently is a C 1 -C 20 linear, branched or cyclic alkyl group or a C 2 -C 4 cyclic alkylene group which forms a fused ring system group; R 2 is a C 1 -C 6 linear, branched or cyclic alkylene, a Si 1 -Si 2 alkyl substituted silanylene group or an alkyl substituted silaalkylene group; each X independently is an alkyl, aryl, halide, hydride or oxygen bridge of a zirconocene dimer; "y" is a number 2, 3 or 4, and "b" is a number 0 or 1. M is preferably zirconium. Most preferably, the supported zirconocene/alumoxane catalyst is prepolymerized with ethylene or another olefin to provide spherical, free-flowing catalyst particles which give free-flowing particulate elastomer product from the slurry polymerization.

Inventors

• 👤 Elvin L. Hoel

Bibliographic Details