Process for the polymerisation of olefins in the gas phase

摘要

A process for polymerising ethylene or copolymerising ethylene and an alpha -olefin(s) in the gas phase comprises: (1) in a first stage prepolymerising ethylene and optional alpha -olefin(s) in the gas phase at 20-70[deg]C in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator; and (2) in a second stage polymerising ethylene and optional alpha -olefin(s) in the gas phase at 65-100[deg]C in the presence of the prepolymer obtained from stage (1).