Patent ID: 7332556
Filing Date: 2008-02-19
Classification: C08F

Abstract:
1. Crystalline homopolymers of propylene or copolymers of propylene with from 0.5 to 6%, by weight with respect to the copolymer, of ethylene, a C 4-8 alpha-olefin or both, prepared by continuous sequential polymerization in at least two stages in the presence of a catalyst consisting essentially of a magnesium halide supported solid catalyst component, an Al-alkyl compound, and an external electron donor compound consisting of a silane compound having bonded to the silicon atom at least one cyclopentyl group and one or more -OR group wherein R is C and having a MIL>2g/10 minutes, an intrinsic viscosity [η] in tetrahydronaphthalene at 135° C.≦2.8 dl/g, a Mw/Mn>20, a content of fraction insoluble in xylene at 25° C.≧94, flexural modulus from 1600 to 2700 MPa, notched Izod at 23° C. from 15 to 100 J/m, and stress at yield from 35 to 45 MPa, from 10 to 60% by weight of a fraction (A) having [η]≧2.6 dl/g, and from 40 to 90% of a fraction (B) having MIL≧50 g/10 minutes and [η]≦1.2 dl/g, further comprising from 0.05 to 2% by weight of a nucleating agent with respect to the weight of said polymers and copolymers.