Patent ID: 6878784
Filing Date: 2005-04-12
Classification: C08L,Y10S,Y10T

Abstract:
1. A multimodal polethylene composition for pipes, which multimodal polyethylene has a density of 0.930-0.965 g/cm 3 and an MFR 5 of 0.2-1.2 g/10 min, chacterised in that the multimodal polyethylene has an M n of 8000-15000, an M w of 180-330×10 3 , and an M w /M n of 20-35, said multimodal polyethylene comprising a low molecular weight (LMW) ethylene homopolymer fraction polymerized in the presence of a Ziegler Natta catalyst and with the addition of 350-450 moles of H 2 /kmoles of ethylene and a high molecular weight (HMW) ethylene copolymer fraction polymerized in the presence of a Ziegler Natta catalyst said HMW fraction having a lower molecular weight limit of 3500, and a weight ratio of the LMW fraction to the HMW faction of (35-55):(65-45).