Single catalyst low, medium and high density polyethylenes
AssigneeUnivation Technologies, LLC
InventorsRainer Kolb, John Szul
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Abstract
A method of polymerizing olefins comprising combining in one embodiment ethylene and optionally one or more α-olefins with a catalyst composition in a continuous polymerization reactor at a pressure of less than 10,000 kPa; wherein the catalyst composition comprises a hafnocene; and isolating a polyethylene having a density in the range of from 0.930 to 0.975 g/cm3. Also provided is a method of transitioning a continuous polymerization reactor from production of a low density polyethylene to a medium or high density polyethylene. Also provided is a medium to high density polyethylene suitable for injection or rotomolding applications. Also provided is a single catalyst composition suitable for such needs.
Claims19
A method of polymerizing olefins comprising combining ethylene at a partial pressure of at least 1300 kPa and optionally one or more α-olefins selected from the group consisting of hexene, butene, and mixtures thereof, with a catalyst composition in a continuous polymerization reactor at a pressure of less than 10,000 kPa;
- wherein the catalyst composition comprises bis(n-propylcyclopentadienyl)hafnium dichloride and an activator;
- and isolating a polyethylene having a density in the range of from 0.930 to 0.975 g/cm3;
- and further characterized in that as the molar ratio of α-olefin to ethylene present in the reactor ranges from 0 to 0.20, the catalyst productivity does not vary by more than 30%.
Dependencies are inferred from the claim text.