Patent ID: 8895466

Claim:
A metallocene catalyst system comprising: (a) a hafnium-based metallocene catalyst component described by formula I R″(CpR 4 )(FluR′ 8 )Hf Q 2 (I) wherein Cp is a cyclopentadienyl ring; Flu is a fluorenyl ring; each R is the same or different and is hydrogen or a hydrocarbyl radical containing from 1 to 20 carbon atoms; each R′ is the same or different and is hydrogen or a hydrocarbyl radical containing from 1 to 20 carbon atoms; R″ is a structural bridge between two Cp rings; Q is a hydrocarbyl radical having from 1 to 20 carbon atoms, a hydrocarboxy radical having from 1 to 20 carbon atoms or a halogen and can be the same or different from each other; and (b) an activating agent having a low or no co-ordinating capability comprising an aluminoxane and a Lewis base, wherein the activating agent comprises a ratio of Lewis base to total aluminum of from 0.5:1 to 0.9:1.