ETHYLENE--g(a)-OLEFIN/DIOLEFIN POLYMER SOLUTION POLYMERIZATION PROCESS

This invention is a solution process for the preparation of ethylene- alpha -olefin/diolefin copolymers comprising contacting ethylene, one or more alpha -olefin monomer, and optionally one or more diene monomer, with a catalyst system containing a catalyst activator and a Group 4 metallocene compound, comprising a) conducting the polymerization reaction at a temperature of about 60 DEG to 150 DEG C.; b) selecting as the Group 4 metallocene compound one or more members of the group consisting of cyclic monocyclopentadienyl Group 4 metal and covalently bridged (bis)indenyl hafnium metallocene compounds; and c) maintaining the alpha -olefin concentration at a molar ratio to that of ethylene of between about 0.3 to 7.0 and a diolefin to ethylene molar ratio of between about 0.01 and 0.4. In a preferred embodiment the process comprises: 1) mixing with a reaction solvent the one or more alpha -olefin monomer, the optional one or more diene monomer, and the catalyst activator, either together or separately, therafter 2) mixing with the reaction solvent an effective scavenging compound prior to or with introduction of the unactivated Group 4 metallocene compound under conditions such that the scavenging compound is in contact with the activator compound for a period of time not exceeding about 1 minute, and 3) contacting the activator compound with the unactivated Group 4 metallocene compound in the presence of said monomers. The process can be advantageously practiced a reaction temperature of at least 60 DEG C., preferably above 80 DEG C., most preferably above 110 DEG C., to achieve high number average molecular weight polymer having high alpha -olefin monomer and diene monomer contents with high diene conversion rates. The process is particularly suitable for the preparation of elastomeric ethylene-propylene or ethylene-propylene-diene monomer elastomers.