Catalytic polymerization of ethylene with supported chromium [II] catalyst in the presence of a phenolic antioxidant

Claim 1

In a process for polymerizing a monomer charge comprising at least a major amount of ethylene by contacting said charge with a catalyst comprising chromium [11] compound supported on activated inorganic oxide, the improvement which comprises employing said catalyst in the presence of a phenolic antioxidant of the formula: ##STR10## wherein each R is independently C 4 to C 12 branched hydrocarbon radicals with steric factors, Es, less than -1.5; R 1 , R 2 and R 3 are independently hydrogen, saturated or unsaturated aliphatic hydrocarbon radicals or aryl radicals which are unsubstituted with polar groups or substituted with polar groups, wherein the aryl radicals containing the polar groups contain R groups in adjacent position thereto, and said chromium [II] compound is of the formula: Ar--Cr[II]-Ar' wherein Ar and Ar' are the same or different and are radicals of the structure: (a) cyclopentadienyl radicals of the structure ##STR11## where each (R 1 ) is independently C 1 to C 20 hydrocarbon radicals, and each m 1 is an integer of 0 to 5; (b) indenyl radicals of the structure: ##STR12## wherein the (R)s are the same or different C 1 to C 10 , hydrocarbon radicals, and n is an integer of 0 to 4 and x is an integer of 0 to 3, and (c) fluorenyl radicals of the structure: ##STR13## wherein the (R)'s may be the same or different C 1 to C 10 hydrocarbon radicals, m and m' may be the same or different integers of 0 to 4 inclusive, and (Z) is H or (R 3 ) and z is 0 or 1.