Patent ID: 6355725
Filing Date: 2002-03-12
Classification: C08L

Abstract:
A process of producing a propylene-ethylene block copolymer composition comprising the sequential steps of:a) continuously supplying an olefin polymerization catalyst and a propylene monomer to the top area of a tubular continuous polymerization apparatus to produce a polypropylene segment (A); b) continuously supplying an ethylene monomer to the intermediate area of the tubular type continuous polymerization apparatus in which the ethylene monomer and the propylene monomer unreacted in the step (a) are copolymerized to produce an ethylene-propylene random copolymer segment (B) and sequentially the segment (B) is chemically bonded to the terminal of the polypropylene segment (A) by a covalent bond to produce an A-B type propylene-ethylene block copolymer (C); c) transferring the A-B type propylene-ethylene block copolymer (C) containing the olefin polymerization catalyst produced in the step (b) to a single- or multi-stage polymerization reactor equipped with an agitator; d) supplying a propylene monomer or a mixed monomer of a propylene monomer and a copolymerizable monomer therewith to the polymerization reactor, followed by copolymerizing in the presence of the olefin polymerization catalyst and the A-B type propylene-ethylene block copolymer (C) to produce a propylene polymer (D1); and e) supplying a mixed monomer of ethylene and propylene to the polymerization reactor, followed by copolymerizing in the presence of the olefin polymerization catalyst, the A-B type propylene-ethylene block copolymer (C) and the propylene polymer (D1) to produce an ethylene-propylene random copolymer (D2), wherein each polymerization time in the steps a) and b) is controlled within the range of from 0.01 to 10 seconds.