Ethylene copolymers process for the preparation of ethylene-based polymers and catalyst system used therein

摘要

A process for the preparation of ethylene polymers is disclosed, comprising the polymerization reaction of ethylene in the presence of a catalyst consisting of the reaction product of: (A) a mixture of the racemic and meso isomers of a stereorigid metallocene compound of a transition metal, belonging to Groups III, IV or V or the lanthanides in the Periodic Table of the Elements, with two cyclopentadienyl ligands connected to each other by a chemical bridge, and (B) at least one co-catalyst capable of activating both the racemic form and the meso form of the metallocene compound, selected from the alumoxanes and the compounds capable of forming an alkylmetallocene cation. In particular the process is suitable to prepare ethylene copolymers with uniform distribution of the comonomer along the polymer chain and broad molecular weight distribution.