| 摘要 |
A process for producing polypropylene, the process comprising homopolymerising propylene or copolymerising propylene with one or more comonomers selected from ethylene and C4 to C10 1-olefins in the presence of a metallocene catalyst system comprising (a) a metallocene catalyst of general formula R''(XRm)(Cp'R'n)M2, wherein X is a cyclopentadienyl moiety (Cp) or a heteroatom, Cp' is a substituted or unsubstituted fluorenyl ring; each R is independently hydrogen or hydrocarbyl having 1 to 20 carbon atoms in which O<=m<=4; each R' is independently hydrocarbyl having 1 to 20 carbon atoms in which 0<=n<=8; R'' is a bridge which comprises a C1-C20 alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphine or amine radical, which bridge is substituted or unsubstituted, M is a Group IVB transition metal, vanadium or a lanthanide metal and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen, and (b) a cocatalyst which activates the catalyst component, the homo- or co-polymerisation being performed in a slurry process in a hydrocarbon diluent for the polypropylene or being performed in a solution process in a hydrocarbon solvent for the polypropylene, the concentration of propylene monomer in the diluent or solvent being lower than 70% by weight, based on the weight of the diluent or solvent, to produce a polypropylene homopolymer or copolymer having long chain branches on the polypropylene molecules.
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