Patent ID: 6646044
Filing Date: 2003-11-11
Classification: C08F,Y10S

Abstract:
A process for continuously producing a propylene-based block copolymer, comprising:polymerizing an &agr;-olefin comprising liquid propylene as a main component in the presence of hydrogen and a stereoregular polymerization catalyst in one or more polymerization reactors to obtain a polymer slurry; feeding said polymer slurry to a copolymerization reactor; and copolymerizing propylene and an &agr;-olefin other than propylene substantially in a gaseous phase in the presence of said stereoregular polymerization catalyst, said polymer slurry and a deactivating compound in said copolymerization reactor to obtain a propylene-block copolymer powder; wherein said polymer slurry, discharged from one of said one or more polymerization reactors, is classified using a classification system to obtain a) a classified polymer slurry containing a large amount of particles having a large particle diameter and b) a classified polymer slurry containing a large amount of particles having a small particle diameter and a main part of said classified polymer slurry containing a large amount of particles having a small particle diameter is recycled to a final polymerization reactor of said one or more polymerization reactors; wherein a part of said classified polymer slurry containing a large amount of particles having a small particle diameter is transferred to a low pressure gas post treatment system; and wherein said classified polymer slurry containing a large amount of particles having a large particle diameter is transferred to said copolymerization reactor.