Polymer composition for pipes
OwnerLars Erik Ahlstrandinventor
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Abstract
HDPE compositions comprising a bimodal polymer and a nucleating agent, for production of pipes having increased pressure resistance, and the use of such compositions in the production of pipes.
Claims23
A polymer composition comprising an ethylene homopolymer or an ethylene alpha-olefin copolymer for producing pipes with increased pressure resistance, wherein the polymer is a bimodal polymer produced in a multistage process comprising
- i) a low molecular weight ethylene polymer and
- ii) a high molecular weight ethylene polymer or copolymer
- and a nucleating agent.
A polymer composition according to any preceding claim, characterized in that the density is between 930 and 965 kg/m3.
A polymer composition according to any preceding claim, characterized in that the melt index MFR5 measured at 190° C. under 5 kg load is between 0.1 and 1.2 g/10 min.
A polymer composition according to any preceding claim, characterized in that the polymer composition comprises 30-70% of said low molecular weight ethylene polymer and 70-30% of said high molecular weight ethylene polymer or copolymer.
A polymer composition according to any preceding claim, characterized in that the number average molecular weight Mn is between 8000 and 150000 g/mol.
A polymer composition according to any preceding claim, characterized in that the weight average molecular weight Mw is between 180000 and 330000 g/mol.
A polymer composition according to any preceding claim, characterized in that the polydispersity index Mw/Mn is between 20 and 40.
A polymer composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a weight average molecular weight of between 5000 and 50000 g/mol.
A polymer composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a melt index MFR2 measured under 2.16 kg load of between 50 and 2000 g/10 min.
A polymer composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a density between 960 and 980 kg/m3.
A polymer composition according to any preceding claim, characterized in that the high molecular weight ethylene polymer or copolymer has a weight average molecular weight of between 300000 and 1000000 g/mol.
A polymer composition according to any preceding claim, characterized in that the high molecular weight ethylene copolymer has a comonomer content of 0.7 to 7.0 mol %.
A polymer composition according to any preceding claim, characterized in that the nucleating agent is a pigment.
A polymer composition according to any preceding claim, characterized in that the nucleating agent is a phthalocyanine blue or green pigment.
A polymer composition according to any preceding claim, characterized in that the nucleating agent is present in an amount of between 1 and 1500 ppm.
A polymer composition comprising an ethylene homopolymer and an ethylene alpha-olefin copolymer for producing pipes with increased pressure resistance, wherein the polymer is a bimodal polymer comprising
- i) a low molecular weight ethylene polymer and
- ii) a high molecular weight ethylene polymer or copolymer
- and a nucleating agent, whereby the pressure resistance MRS according to ISO/TR 9080 is at least 10% higher than for the same polymer composition not comprising a nucleating agent.
Use of a polymer composition comprising an ethylene homopolymer and an ethylene alpha-olefin copolymer, whereby the polymer is a bimodal polymer and comprises
- i) a low molecular weight ethylene polymer and
- ii) a high molecular weight ethylene polymer or copolymer
- and a nucleating agent for producing pipes with increased pressure resistance.
Dependencies are inferred from the claim text.