Patent ID: 8022124

Claim:
A process for preparation of ethylene homopolymers or copolymers, comprising the steps of a) polymerizing in a single reactor ethylene or ethylene with one or more other 1-olefins in the presence of a chromium catalyst at a temperature within the range of 20 to 200° C. and at a pressure within the range of 0.1 to 20 MPa, where the chromium catalyst can be prepared via application of one or more chromium compounds to a silicate support and subsequent thermal activation under oxidative conditions at a temperature within the range of 620 to 900° C., and b) mixing the polyethylene in the melt with from 1000 to 2000 ppm of an antioxidant comprising at least one sterically hindered phenol and at least one phosphite in a mixing ratio of from 1:5 to 5:1, with specific energy input of at least 0.17 kWh/kg, wherein the polymerization takes place in the presence of from 1 to 12 ppm of an antistatic agent.