Daniel J. Gillis - West Haven CT
Richard Karpeles - Cheshire CT
Uniroyal Chemical Company, Inc. - Middlebury CT
A liquid phase polymerization process is provided for producing a polyolefin elastomer, e. g. , one derived from ethylene, another. alpha. -olefin such as propylene and, optionally, a diene, employing a metallocene catalyst. The process comprises contacting monomer under liquid phase polymerization conditions with a catalyst composition obtained by combining (a) a metallocene procatalyst, preferably one containing a bridging group possessing at least two bulky groups, and (b) a cocatalyst such as aluminoxane, preferably a cation-generating cocatalyst, in partial on total replacement of aluminoxane.