| 摘要 |
The present invention relates to a polyethylene composition for pipe applications comprising a base resin having a density of more than 946.0 kg/m 3 and equal to or less than 955.0 kg/m 3 , wherein the composition has a MFR 21 of 1.7 to 7.0 g/10 min and a FRR 21/5 of more than 10 to equal to or less than 40, and a polyethylene composition obtainable by a multistage process, the multistage process comprising polymerizing ethylene in the presence of a silica supported Ziegler Natta catalyst in a first loop reactor, transferring a first intermediate material to a second loop reactor, further polymerizing said first intermediate material for obtaining a second intermediate material and transferring said second intermediate material to a gas phase reactor, feeding ethylene and comonomer to the gas phase reactor for obtaining a base resin, and finally extruding the base resin together with stabilizers and carbon black into the polyethylene composition. The invention further concerns a multistage process for the production of the polyethylene composition and articles, preferably pipes, made from the inventive polyethylene composition. |
