Patent ID: 6855782

Claim:
In a method for the stereotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer, the steps comprising: a) providing a supported metallocene catalyst comprising a stereospecific metallocene catalyst component and an aluminum containing a co-catalyst component comprising at least one of an alkyl alumoxane and an alkylaluminum compound, said stereospecific metallocene incorporating a metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated with a central transition metal atom; at least one of said cyclopentadienyl ring structures being a substituted cyclopentadienyl group which provides an orientation with respect to said transition metal atom which is sterically different from the orientation of the other cyclopentadienyl group with respect to said transition metal atom, and both of said cyclopentadienyl groups being in a relationship with each other providing a stereorigid relationship relative to said coordinating transition metal atom to prevent rotation of said ring structures, said metallocene catalyst component and said co-catalyst component being supported on a particulate silica support comprising spheroidal silica particles having an average diameter within the range of 5-40 microns and an average effective pore size within the range of 50-350 angstroms and containing at least 50 wt. % of the supported catalyst component within the pore volume of said particulate silica support; and b) contacting said catalyst in a polymerization reaction zone with an ethylenically unsaturated monomer which contains 3 or more carbon atoms or which is a substituted vinyl compound and maintaining said reaction zone under polymerization conditions to produce stereospecific polymerization of said monomer with an attendant rupturing of said silica support to produce secondary silica support particles having an average particle size of no more than 12 microns.