Activator supports impregnated with group VIII transition metals for polymer property control
AssigneeChevron Phillips Chemical Company LP
InventorsMax P. McDaniel, Qing Yang, Tony R. Crain, Kathy S. Collins
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Abstract
Methods for controlling properties of an olefin polymer using a Group VIII transition metal-modified activator-support are disclosed. The melt index of the polymer can be decreased and the molecular weight of the polymer can be increased via the addition of the transition metal-modified activator-support to the polymerization reactor system.
Claims27
A method for reducing a melt flow property of an olefin polymer, the method comprising:
- (a) contacting a catalyst composition with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce the olefin polymer,
- wherein the catalyst composition comprises a metallocene compound, an activator-support, and an optional co-catalyst;
- and
- (b) introducing an amount of a transition metal-modified activator-support into the polymerization reactor system to reduce the melt flow property of the olefin polymer,
- wherein the transition metal-modified activator-support comprises a solid oxide treated with an electron-withdrawing anion and impregnated with a Group VIII transition metal, and wherein the electron-withdrawing anion comprises sulfate and/or fluoride.
A method for increasing a molecular weight parameter of an olefin polymer, the method comprising:
- (a) contacting a catalyst composition with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce the olefin polymer,
- wherein the catalyst composition comprises a metallocene compound, an activator-support, and an optional co-catalyst;
- and
- (b) introducing an amount of a transition metal-modified activator-support into the polymerization reactor system to increase the molecular weight parameter of the olefin polymer,
- wherein the transition metal-modified activator-support comprises a solid oxide treated with an electron-withdrawing anion and impregnated with a Group VIII transition metal, and wherein the electron-withdrawing anion comprises sulfate and/or fluoride.
An olefin polymerization process, the process comprising contacting a catalyst composition with an olefin monomer and an optional olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer, wherein the catalyst composition comprises a metallocene compound, a transition metal-modified activator-support, and an optional co-catalyst,
- wherein the transition metal-modified activator-support comprises a solid oxide treated with an electron-withdrawing anion and impregnated with a Group VIII transition metal, and wherein the electron-withdrawing anion comprises sulfate and/or fluoride;
- and
- wherein a melt index (MI) of the olefin polymer produced by the process is at least 10% less than a MI of an olefin polymer obtained under the same polymerization conditions using an activator-support without the Group VIII transition metal.
Dependencies are inferred from the claim text.