Process

Abstract

The invention provides a process for the preparation of a multimodal high density polyethylene (HDPE) having a density of greater than 950 kg/m, a Mz of at least 1000 kDa and a melt flow rate (MFR5) of 0.01 to 4.0 g/10 min, said process comprising: (i) polymerising ethylene in a first polymerisation stage in the presence of a Ziegler-Natta catalyst to prepare a first ethylene homopolymer; (ii) polymerising ethylene in a second polymerisation stage in the presence of said catalyst and said first ethylene homopolymer to prepare an ethylene homopolymer mixture comprising said first ethylene homopolymer and a second ethylene homopolymer; and (iii) polymerising ethylene and at least one alpha-olefin comonomer in a third polymerisation stage in the presence of said catalyst and said ethylene homopolymer mixture to prepare said multimodal HDPE; wherein the split for the third polymerisation stage is at least 50%.

Dependencies are inferred from the claim text.