Multistage copolymerization process

Claim 1

A continuous process for the preparation of propylene-ethylene impact copolymers comprising: (a) homopolymerizing propylene in a plug flow pipeline reactor in the presence of a liquid medium or high density supercritical phase comprising propylene monomer as a major constituent and in the presence of magnesium chloride and titanium-containing catalyst particles, resulting in a homopolymer slurry; (b) transferring said homopolymer slurry to a gas-phase fluidized bed homopolymer reactor and homopolymerizing additional propylene; (c) removing a stream of propylene homopolymer particles from said gas-phase fluidized bed homopolymer reactor and transferring the stream to a gas-phase fluidized bed copolymer reactor; (d) copolymerizing ethylene and propylene in said copolymer reactor, resulting in a propylene-ethylene impact copolymer; and (e) removing said propylene-ethylene impact copolymer as a product stream from said copolymer reactor.