Patent ID: 6087459
Filing Date: 2000-07-11
Classification: C08F

Abstract:
A method of forming a polymer comprising:subjecting propylene monomers to polymerization in the presence of a Ziegler-Natta catalyst and a blend of at least two electron donors, said blend of electron donors comprising about 2.5 mol. % to less than 50 mol. % of a first electron donor based on total mol. % of electron donors wherein the first electron donor consists essentially of dicyclopentyldimethoxysilane (DCPMS) and greater than 50 mol. % of a second electron donor based on total mol. % of electron donors wherein the second electron donor consists essentially of propyltriethoxysilane (PTES) and wherein a relationship between the first electron donor and a second electron donor is defined by an equation;1.2.ltoreq.log [MFR(b)/MFR(a)].ltoreq.1.4wherein MFR(a) is a first melt flow rate of a homopolymer formed by polymerizing propylene monomers in the presence of the Ziegler-Natta catalyst and the first electron donor, and wherein MFR(b) is a second melt flow rate of a homopolymer formed by polymerizing propylene monomers in the presence of the Ziegler-Natta catalyst and the second electron donor, and wherein the MFR(a) is lower than the MFR(b).