LOW MOLECULAR WEIGHT ETHYLENE COPOLYMERS
Publication Date: 2003-Oct-10
The IP.com Prior Art Database
Low molecular weight olefin polymers are prepared by a polymerization process employing titanium complexes comprising a 3-aryl- substituted cyclopentadienyl ring or substituted derivatives thereof as polymerization catalysts.
Certain catalyst compositions have been found to be highly effective in the preparation of ethylene/ a-olefin copolymers having weight average molecular weights less than 100,000, preferably less than 50,000, with high comonomer incorporation of greater than 5 weight percent, more preferably greater than 10 weight percent (based on total polymer weight), and high catalyst efficiencies. Catalyst efficiencies under solution polymerization temperatures from 95 to 160 °C, preferably from 100 to 155 °C, of greater than 400,000 g polymer/ g Ti, preferably greater than 1x106 g polymer/g Ti are obtained. The polymers are readily prepared using extremely low levels of hydrogen or other separately added chain transfer agent. In particular, the molar ratio of hydrogen to monomer is desirably less than 0.01.
The resulting copolymers consisting essentially of ethylene and one or more C4-10 a-olefins are low molecular weight polymers, waxes or oils having a melt index (ASTM D-1238, 190 °C, 2.16 kg) greater than 10, preferably greater than 100. The resulting copolymers of ethylene, propylene, and optionally one or more of norbornadiene, ethylidene-norbornene, or a C4-40 diene as well as the copolymers of ethylene, a C4-10 a-olefin, and one or more of norbornadiene, ethylidene-norbornene, or a C4-40 diene are low molecular elastomers or low molecular weight tackifiers or extenders for use in adhesive formulations, desirably having a Mooney Viscosi...