Patent ID: 6617403
Filing Date: 2003-09-09
Classification: C08F

Abstract:
A polymerization process comprising contacting in a reaction zone, at a temperature within a range of about 180Â° F. to about 215Â° F., in the absence of hydrogen:a) ethylene monomer; b) at least one mono-1-olefin comonomer having from about 2 to about 8 carbon atoms per molecule; c) a catalyst system comprising chromium supported on a silica-titania support, wherein said support comprises from about 2 to about 10 weight percent titanium, based on the weight of the support, and wherein said catalyst system has been activated in oxygen at a temperature within a range of about 900Â° F. to about 1050Â° F. and has not been subjected to a reduction treatment; and d) a trialkyl boron compound; and recovering an ethylene/mono-1-olefin copolymer, wherein the ethylene/mono-1-olefin copolymer has a critical shear rate for the onset of melt fracture greater than about 1900 secâˆ’1.