Patent ID: 7666959

Claim:
A metallocene catalyst system for producing a polyolefin having a molecular weight distribution of from 7 to 20 comprising: (a) a first constituent comprising a bridged hafnocene-based catalyst component having at least one cyclopentadienyl group effective for producing a high molecular weight fraction, based on a weight average molecular weight of the polyolefin, and wherein the hafnocene-based catalyst component has a structure according to formula II: R″(CpR n ) g HfXQ 3-g (II) wherein: each Cp is a substituted or unsubstituted cyclopentadienyl ring; each R is the same or different and is hydrogen or a hydrocarbyl radical containing from 1-20 carbon atoms or 2 carbon atoms are joined together to form a C 4 -C 6 ring; R″ is a structural bridge between two Cp rings; Q is a hydrocarbyl radical having from 1-20 carbon atoms or a halogen and can be the same or different from each other; n is 4; g is 2; and X is a hetero atom ligand wherein the hetero atom is nitrogen, phosphorus, oxygen or sulfur; (b) a second constituent comprising at least one metallocene or post-metallocene component different from component (a) and effective for producing a low molecular weight fraction, based on a weight average molecular weight, of the polyolefin and wherein the metallocene catalyst component is an unbridged zirconocene substituted with at least one bulky substituent and the post-metallocene catalyst component is an iron complex of a 2,6-bis(imino)pyridyl ligand; and (e) an activating agent having a low or no coordinating capability and selected from the group consisting of a borate, a borane or an aluminate.