Patent ID: 6465586
Filing Date: 2002-10-15
Classification: C08F

Abstract:
A process for producing a copolymer of ethylene and 1-hexene wherein said copolymer has a high load melt index (HLMI) within the range of about 5 to about 25 g/10 minutes, a density in the range of about 0.95 to about 0.96 g/cc, a shear response (HLMI/MI) within the range of about 140 to about 230, an Mw/Mn of about 15 to about 30, a weight swell of less than about 380%, and a die swell of less than about 42%, an ESCR (Condition A) of greater than about 400 hours, an onset of melt fracture of at least about 2000 sec- 1, and a 1-minute output test value of at least about 1200 grams per minute, xylene solubles of less than 0.7%, and less than 2.0 weight % material of molecular weight less than 1000, comprising contacting under slurry polymerization conditions in an isobutane diluent at a temperature of from about 200Â° F. to 230Â° F.a) ethylene monomer; b) 1-hexene, c) a catalyst comprising chromium supported on a silica-titania support, wherein said catalyst is prepared by coprecipitating the chromium with the silica and titania to produce a product which is aged twice, wherein the first aging is at a substantially neutral pH and wherein the second aging is at an alkaline pH, and wherein the catalyst contains about 0.8 to 1.5 weight percent chromium, said support comprises about 2.5 weight percent titanium, based on the weight on the support, wherein said catalyst has a surface area in the range of about 300 m2/gm to about 500 m2/gm, a pore volume in the range of about 0.8 to about 1.1 ml/gm, and said catalyst has been activated at a temperature within a range of about 538Â° C. to about 650Â° C.; d) about 0.1 to about 2.0 mg/kg, based on the reactor diluent, of a trialkylboron compound; and e) recovering the copolymer.