Multimodal polyolefin pipe
AssigneeNOVA Chemicals (International) S.A.
InventorsAlexei Kazakov, Stephen John Brown, Christopher John Brooke Dobbin, Stanley Allan Grabow
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Abstract
A solution polymerization process in a series or parallel of two or more reactors at different temperatures is used to prepare a multimodal polyolefin resin of narrow molecular weight distribution. This resin is used to manufacture melt extruded pipe that has an improved performance at elevated temperatures and an improved hydrostatic design.
Claims19
A multimodal polyolefin resin comprising not less than 80 weight % of ethylene and up to 20 weight % of one or more C3-10 alpha olefins, said composite resin having a density greater than 0.940 g/cm3;
- a melt index determined according to ASTM D 1238 under a load of 2.16 kg and a temperature of 190° C. greater than 0.01 g/10 minutes, a polydispersity greater than 3.5, and a CDBI of greater than 50 comprising at least:
- a) from 5 to 50 weight % of a high molecular weight component having a density greater than 0.940 g/cm3;
- a weight average molecular weight greater than 250,000;
- a polydispersity from 1.5 to 3.5;
- and a short chain branch content from 0.0 to 4.4 short chains per 1000 carbon atoms in the polymer backbone;
- and
- b) from 50 to 95 weight % of a lower molecular weight component having a density from 0.930 to 0.960 g/cm3;
- a weight average molecular weight greater than 25,000;
- a polydispersity from 2.0 to 3.5;
- and a short chain branch content from 0.5 to 6.1 short chains per 1000 carbon atoms in the polymer backbone.
Dependencies are inferred from the claim text.