Process for producing polyolefins and polyolefin catalysts
AssigneePhillips Petroleum Company
InventorPhil M. Stricklen
Life of this patent
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Abstract
A process for producing a polyolefin having a multimodal molecular weight distribution wherein the polymerization is conducted in the presence of hydrogen and a catalyst system containing aluminoxane and at least two different metallocenes each having different olefin polymerization termination rate constants in the presence of hydrogen, and the process of producing the catalyst system.
Claims27
A process for producing polyolefins having bimodal molecular weight distribution comprising:
- polymerizing under polymerization conditions in a polymerization zone at least one olefin in the presence of an amount of hydrogen and a heterogeneous catalyst system comprising:
- (a) an amount of at least two different metallocenes selected from mono, di, and tri-cyclopentadienyls and substituted cyclopentadienyls of a transition metal selected from the group consisting of Group IVB, VB, and VIB transition metals, each having different termination rate constants of olefin polymerization in the presence of hydrogen, and
- (b) an amount of an aluminoxane,
- wherein the initial amount of hydrogen, metallocenes, and aluminoxane in said polymerization zone is sufficient to produce a polyolefin having a bimodal molecular weight distribution.
A process of altering the bimodal molecular weight distribution of a polyolefin comprising:
- varying the initial amount of hydrogen present during the polymerization of an olefin in the presence of a heterogeneous catalyst system under polymerization conditions comprising
- (a) at least two different metallocenes selected from mono, di, and tri-cyclopentadienyls and substituted cyclopentadienyls of a transition metal selected from the group consisting of Group IVB, VB, and VIB transition metals, each having different termination rate constants of olefin polymerization in the presence of hydrogen, and
- (b) an aluminoxane
- thereby producing a polyolefin having a varied bimodal molecular weight distribution.
A process for producing polyolefins having bimodal molecular weight distribution comprising:
- polymerizing under polymerization conditions at least one olefin in the presence of a heterogeneous catalyst system comprising
- (a) at least two different metallocenes selected from mono, di, and tri-cyclopentadienyls and substituted cyclopentadienyls of a transition metal selected from the group consisting of Group IVB, VB, and VIB transition metals, each having different termination rate constants of olefin polymerizations in the presence of hydrogen and
- (b) an aluminoxane,
- wherein the improvement comprises the addition of hydrogen during the polymerization to alter the bimodalmolecular weight distribution of the resulting polymer.
Dependencies are inferred from the claim text.