Patent ID: 6355731
Filing Date: 2002-03-12
Classification: C08F,C08L

Abstract:
A process for the preparation of a heterophasic polyolefin composition comprising:i) polymerizing, in any given order, a) monomers selected from the group consisting of: (1) propylene, whereby a crystalline propylene polymer that is at least 80% by weight insoluble in xylene at ambient temperature is formed, (2) propylene and ethylene, (3) propylene and a C4-C10 &agr;-olefin, (4) propylene, ethylene and a C4-C10 &agr;-olefin, whereby a crystalline propylene copolymer containing more than 85% by weight of propylene is formed, (5) ethylene, whereby an ethylene homopolymer is formed, and (6) ethylene and a C3-C12 &agr;-olefin, whereby an ethylene copolymer containing up to 20% by mole of the C3-C12 &agr;-olefin is formed, and b) copolymerizing ethylene and a C3-C10 &agr;-olefin, and, optionally, a diene, to form an elastomeric copolymer partially soluble in xylene at ambient temperature, containing up to 70% by weight of ethylene in the fraction soluble in xylene at ambient temperature, â€ƒwherein the polymerizations are carried out in the presence of a Ziegler-Natta catalyst (1) obtained by contacting the following components: (a) a catalytic component containing a titanium compound and an electron-donor compound, both supported on Mg chloride; (b) an organometallic compound, and, optionally, (c) an electron-donor compound; ii) contacting the polymer obtained in (i), in any given sequence, with: a) a compound capable of deactivating the catalyst present in (i); and b) a catalyst (2) obtained by contacting: (I) a compound containing a transition metal M, and at least one ligand coordinated with metal M by a &pgr; bond, and (II) at least one cocatalyst; and iii) copolymerizing ethylene and a C3-C10 &agr;-olefin in the presence of the polymer treated as in (ii), and the catalyst (2).