Patent ID: 7439312
Filing Date: 2008-10-21
Classification: C08F,Y10S

Abstract:
1. A process for preparing a unimodal polymer composition comprising: (a) combining a first metallocene catalyst compound comprising a zirconium or hafnium with propylene monomers in a polymerization medium; (b) conducting polymerization of the propylene monomers in the polymerization medium with the first metallocene catalyst compound to form vinyl, vinylene or vinylidene terminated polypropylene macromer with a weight average molecular weight of less than 100,000 Daltons; (c) combining a second metallocene catalyst compound comprising a zirconium or hafnium with the polymerization medium; (d) conducting polymerization of the propylene monomers in the polymerization medium with the second metallocene catalyst compound to form a crystalline polypropylene with a weight average molecular weight of 100,000 Daltons or more; (e) incorporating at least some of the vinyl, vinylene or vinylidene terminated polypropylene macromers into the crystalline polypropylene to form a branched crystalline polypropylene polymer; and (f) recovering the branched crystalline polypropylene polymer from the polymerization medium, wherein the first metallocene catalyst compound is a bridged metallocene compound with at least two indenyl or tetrahydroindenyl rings substituted at one or both of the 4 and 7 positions and the second metallocene catalyst compound is a bridged metallocene compound that has at least two indenyl or tetrahydroindenyl rings substituted at the 2 and 4 positions; and wherein the molar amount of the second metallocene catalyst compound is greater than the molar amount of the first metallocene catalyst compound.