| 摘要 |
The present invention deals with coated pipes having a layer of multimodal polyethylene. The multimodal ethylene copolymer is a copolymer of ethylene with one or more alpha-olefin comonomers having from 4 to 10 carbon atoms and has a weight average molecular weight of from 70000 g/mol to 250000 g/mol, the ratio of the weight average molecular weight to the number average molecular weight, Mw/Mn, of from 15 to 50, a melt index MFR2 of from 0.05 g/10 min to 5 g/10 min, a melt index MFR5 of from 0.5 to 10 g/10 min and a density of from 930 kg/m to 955 kg/m3. Further, the multimodal ethylene copolymer comprises the multimodal ethylene copolymer comprises from 49 to 59% based on the weight of the multimodal ethylene copolymer a low molecular weight ethylene homopolymer component, said low molecular weight ethylene homopolymer having a weight average molecular weight of from 5000 g/mol to 70000 g/mol; and from 51 to 41% based on the weight of the multimodal ethylene copolymer a high molecular weight ethylene copolymer component, said high molecular weight ethylene copolymer having a weight average molecular weight of from 100000 g/mol to 700000 g/mol. The pipes can be coated with high throughput and good production economy. The coatings have good mechanical properties.
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