Patent ID: 8445619

Claim:
Process for making a film or a pipe, comprising: compounding an uncompounded polyolefin powder having a particle size distribution such that D95 is less than 355 μm and (D90−D10)/D50 is less than 1.2, where D95, D90, D50 and D10 are defined such that 95 wt %, 90 wt %, 50 wt % or 10 wt % of polymer particles have a diameter of less than D95, D90, D50 and D10 respectively, to form pellets; and then forming the pellets into a film or a pipe, wherein the compounding to form pellets utilises a specific energy of no more than 0.40 kWh/kg, and additionally or alternatively the residence time in a pelletisation extruder is no more than 45 seconds, and wherein the uncompounded polyolefin powder is a multimodal ethylene polymer having a density greater than 940 kg/m 3 and a melt flow index MI 5 of 0.05 to 50 g/10 min, said multimodal ethylene polymer comprising from 30 to 70 wt %, based on the total weight of the multimodal ethylene polymer, of a first polyethylene fraction having a density of at least 950 kg/m 3 and a melt flow index MI 2 of at least 10 g/10 min, and from 70 to 30 wt %, based on the total weight of the multimodal ethylene polymer, of a second polyethylene fraction comprising units of ethylene and optionally up to 5 mol % of at least one other alpha-olefin containing from 3 to 12 carbon atoms, and having a melt flow index MI 2 of less than 10 g/10 min.