Patent ID: 6855783

Claim:
A supported metallocene catalyst composition useful in the polymerization of olefins comprising: a. a particulate silica support having an average particle size within the range of 10-50 microns and a surface area within the range of 200-800 m 2 /g; b. an alkylalumoxane cocatalyst component incorporated onto said silica support to provide a weight ratio of alkylalumoxane to silica of at least 0.8:1; c. a metallocene catalyst component supported on said particulate silica support in an amount of at least 1 weight percent of said silica and said alkylalumoxane and characterized by the formula: B(CpRaRb)(FlR′ 2 )MQ 2 wherein: Cp is a substituted cyclopentadienyl group, Fl is a substituted fluorenyl group, and B is a structural bridge between Cp and Fl imparting stereorigidity to said catalyst, Ra is a substituent on the cyclopentadienyl group which is in a distal position to the bridge and comprises a bulky group of the formula XR* 3 in which X is carbon or silicon and R* is the same or different and is chosen from hydrogen or a hydrocarbyl group having from 1-20 carbon atoms, provided that at least one R* is not hydrogen, Rb is a substituent on the cyclopentadienyl ring which is proximal to the bridge and positioned non-vicinal to the distal substituent and is of the formula YR# 3 in which Y is silicon or carbon and each R# is the same or different and chosen from hydrogen or a hydrocarbyl group containing from 1 to 7 carbon atoms and is less bulky than the substituent Ra, each R′ is the same or different and is a hydrocarbyl group having from 1-20 carbon atoms with one R′ being substituted at a non-proximal position on the fluorenyl group and the other R′ being substituted at an opposed non-proximal position on the fluorenyl group, M is a Group IVB transition metal or vanadium; Q is a halogen or a C 1 -C 4 alkyl group; and d. said alkylalumoxane component and said metallocene component being present in relative amounts to provide an Al/M mole ratio of at least 150.