Rare earth and magnesium based catalyst systems, new neodymium alcoholates and their use in the polymerization of unsaturated compounds

摘要

The invention concerns a catalytic system based on rare earth and magnesium and its use for polymerising unsaturated compounds. The inventive catalytic system is characterised in that it comprises a compound consisting of the reaction product between: a rare earth alcoholate; an organo-magnesium. The alcoholate can be prepared in particular by reacting a rare earth halide with an alkaline or alkaline-earth alcoholate. The invention also concerns a neodymium alcoholate characterised in that the alcoholate is a tert-butylate or a tert-amylate and it does not contain chlorine in its structure. The inventive system can be used more particularly for polymerising methyl ethylene or methacrylate and for copolymerising them.