Polyethylene composition
AssigneeUnivation Technologies, LLC
InventorsSwapnil B. Chandak, Nitin Borse, Ayush A. Bafna, Yi Zhang, Timothy R. Lynn, Roger L. Kuhlman, John F. Szul
Life of this patent
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Abstract
A bimodal linear polyethylene composition, products made therefrom, methods of making and using same, and articles containing same.
Claims12
A bimodal linear medium density polyethylene composition comprising a lower molecular weight (LMW) polyethylene component and a higher molecular weight (HMW) polyethylene component, wherein each of the LMW and HMW polyethylene components comprises ethylene-derived monomeric units and (C3-C20)alpha-olefin-derived comonomeric units;
- and wherein the bimodal linear medium density polyethylene composition is characterized by each of limitations (a) to (d):
- (a) a resolved bimodality showing in a chromatogram of gel permeation chromatography (GPC) of the bimodal linear medium density polyethylene composition, wherein the chromatogram shows a peak representing the HMW polyethylene component, a peak representing the LMW polyethylene component, and a resolved bimodal molecular weight distribution characterized by a local minimum in a range of Log(molecular weight) (“Log(MW)”) 1.5 to 5.0 between the peak representing the HMW polyethylene component and the peak representing the LMW polyethylene component, measured according to Bimodality Test Method;
- (b) a molecular mass dispersity (Mw/Mn), ÐM, from 5 to 30.1, measured according to Gel Permeation Chromatography (GPC) Test Method;
- (c) no measurable amount of long chain branching per 1,000 carbon atoms (“LCB Index”), measured according to LCB Test Method;
- and (d) a density from 0.930 to 0.950 gram per cubic centimeter (g/cm3), measured according to ASTM D792-13 Method B.
A bimodal linear medium density polyethylene composition made by copolymerizing ethylene (monomer) and at least one (C3-C20)alpha-olefin (comonomer) with a mixture of a bimodal catalyst system and a trim solution in the presence of molecular hydrogen gas (H2) and an inert condensing agent (ICA) in a polymerization reactor under (co)polymerizing conditions;
- wherein prior to being mixed together the trim solution consists essentially of a (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complex and an inert liquid solvent and the bimodal catalyst system consists essentially of an activator species, a bis(2-pentamethylphenylamido)ethyl)amine zirconium complex and a (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complex, all disposed on a solid support;
- and wherein the (co)polymerizing conditions comprise a reaction temperature from 80° C. to 110° C., a molar ratio of the molecular hydrogen gas to the ethylene (H2/C2 molar ratio) from 0.001 to 0.050;
- and a molar ratio of the comonomer to the ethylene (Comonomer/C2 molar ratio) from 0.005 to 0.10.
A method of making a bimodal linear medium density polyethylene composition, the method comprising contacting ethylene and at least one (C3-C20)alpha-olefin with a mixture of a bimodal catalyst system and a trim solution in the presence of H2 gas and an inert condensing agent in a polymerization reactor under (co)polymerizing conditions, thereby making the bimodal linear medium density polyethylene composition;
- wherein prior to being mixed together the trim solution consists essentially of a (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complex and an inert liquid solvent and the bimodal catalyst system consists essentially of an activator species, a non-metallocene ligand-Group 4 metal complex and a metallocene ligand-Group 4 metal complex, all disposed on a solid support;
- and wherein the (co)polymerizing conditions comprise a reaction temperature from 80° C. to 110° C. a molar ratio of molecular hydrogen gas to the ethylene from 0.001 to 0.050;
- and a molar ratio of comonomer to the ethylene from 0.005 to 0.10.
Dependencies are inferred from the claim text.