Patent ID: 7781553

Claim:
Polypropylene formed by a process comprising: providing a Ziegler-Natta catalyst component represented by the general formula MR 1 x wherein M is a transition metal; each R 1 is independently selected from halogens, alkoxys and hydrocarboxyl groups and x is the valence of the transition metal; contacting the Ziegler-Natta catalyst component with a co-catalyst component comprising an organoaluminum compound and an external donor system to form a catalyst systems wherein the external donor system comprises: a first external donor, wherein the first external donor comprises cyclohexylmethyldimethoxysilane (CMDS); and a second external donor, wherein the second external donor comprises butylmethyldimethoxysilane (BMDS); and contacting propylene with the catalyst system within a reaction zone to form the polypropylene.