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1. (WO2018002617) POLYETHYLENE FOR PIPES

Pub. No.:    WO/2018/002617    International Application No.:    PCT/GB2017/051892
Publication Date: Fri Jan 05 00:59:59 CET 2018 International Filing Date: Fri Jun 30 01:59:59 CEST 2017
IPC: C08F 210/16
C08F 2/00
C08F 4/6592
Applicants: NORNER VERDANDI AS
GORDON, Kirsteen
Inventors: DRENG, Tore
LUNDQUIST, Morten
LINDROOS, Jarmo
O'HARE, Dermot
BUFFET, Jean-Charles
TURNER, Zoe
FRASER, Duncan
Title: POLYETHYLENE FOR PIPES
Abstract:
The present invention provides a process for the preparation of a multimodal polyethylene, said multimodal polyethylene preferably having a bimodal or trimodal molecular weight distribution, comprising: (i) polymerising ethylene and optionally an α-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an α-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein said first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst, which is a complex of a group 4 to 10 metal having at least two ligands, wherein at least one of the ligands is persubstituted and comprises a delocalised pi system of electrons, each polymerisation stage produces at least 5 %wt of said multimodal polyethylene, and said multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm3.