Patent ID: 8653201

Claim:
Composition comprising polymer of ethylene and from 0.5 to 5 wt % of a C 4 -C 8 alpha-olefin which has a natural density of 935-956 kg/m 3 , a melt index MI 5 of 0.15-0.5 g/10 min, a dynamic complex viscosity at 100 rad/s and 190° C. (η 100 ) of no more than 2500 Pa·s, a relationship between η 100 and dynamic complex viscosity measured in Pa·s at 0.01 rad/s and 190° C. (η 0.01 ), defined by the equation η 0.01 >115000+30. η 100 , and an environmental stress crack resistance as measured by a notched pipe test performed according to ISO13479:1997 on 110 mm SDR 11 pipes at 80° C. and a pressure of 9.2 bar, of greater than 1000 hours, which composition is formed from a multimodal polyethylene resin comprising from 30 to 70 wt % of an ethylene homopolymer (A) having a melt index MI 2 of 100-800 g/10 min and a density of at least 965 kg/m 3 , and from 30 to 70 wt % of a copolymer (B) of ethylene and a C 4 -C 8 alpha-olefin having a density of 910 to 930 kg/m 3 , wherein the ratio of homopolymer (A) to copolymer (B) is 48:52 to 55:45.