Alternating isoprene-ethylene copolymers and a process for the preparation thereof

Abstract

The invention refers to Isoprene-ethylene copolymers having alternating monomer units in which the proportion of recurring -isoprene-ethylene- sequences is more than 80 mol %, in which the proportion of built-in isoprene in the 1,4-configuration is more than 80 mol % which consists of more than 70 mol % of a trans-arrangement, and in which less than 5 mol % of the built-in isoprene is present in the 3,4-configuration, the copolymers having a glass temperature of between -70.degree. C. and -90.degree. C., a Mooney-viscosity of between 30 and 150 [ML 1+4 (100.degree. C.)] and a viscosity number [.eta.], measured at 25.degree. C. in toluene, of between 0.5 and 6, and a process for their preparation characterized in that polymerization is carried out in solution at a temperature of between -80.degree. C. and +100.degree. C. in the presence of a catalyst system which consists of (a) a vanadium compound of the formula VO(OR).sub.2 X and (b) an organoaluminium compound of formula Al R'.sub.3, HAlR'.sub.2 or R'.sub.2 ALY wherein R represents an alkyl group containing from 1-20 carbon atoms, X represents a halogen atom, R'represents an alkyl group containing from 1 to 8 carbon atoms Y represents a halogen atom; whereby the molar ratio of b:a is between 100:1 and 1:10.

Dependencies are inferred from the claim text.