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US 2013/0158216 A1Published application
Use of Hydrogen and an Organozinc Compound for Polymerization and Polymer Property Control
AssigneeChevron Phillips Chemical Company LP
InventorsErrun Ding, Qing Yang, Albert P. Masino, Youlu Yu, Lloyd W. Guatney, Jim B. Askew
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Abstract
Methods of controlling polymerization reactions using a synergistic amount of hydrogen and an organozinc compound are disclosed. The resulting polymers have lower molecular weights and higher melt flow indices.
Claims21
A method of controlling a polymerization reaction in a polymerization reactor system, the method comprising:
- (i) introducing a transition metal-based catalyst composition, an olefin monomer, and optionally an olefin comonomer into a polymerization reactor within the polymerization reactor system, wherein the transition metal-based catalyst composition comprises (a) a transition metal compound;
- (b) an activator-support comprising a solid oxide treated with an electron-withdrawing anion;
- and (c) optionally, a co-catalyst;
- (ii) contacting the transition metal-based catalyst composition with the olefin monomer and the optional olefin comonomer under polymerization conditions to produce an olefin polymer;
- and
- (iii) introducing a synergistic amount of hydrogen and an organozinc compound into the polymerization reactor system to reduce a weight-average molecular weight (Mw) and/or to increase a melt index (MI) of the olefin polymer.
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An olefin polymerization process, the process comprising:
- contacting a transition metal-based catalyst composition with an olefin monomer and optionally an olefin comonomer under polymerization conditions, and in the presence of a synergistic amount of hydrogen and an organozinc compound, to produce an olefin polymer;
- wherein the transition metal-based catalyst composition comprises (a) a transition metal compound;
- (b) an activator-support comprising a solid oxide treated with an electron-withdrawing anion;
- and (c) optionally, a co-catalyst;
- and wherein:
- a Mw of the olefin polymer is less than about 200,000 g/mol;
- a MI of the olefin polymer is greater than about 1 g/10 min;
- or
- both.
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A method of controlling a polymerization reaction in a polymerization reactor system, the method comprising:
- (i) introducing a transition metal-based catalyst composition, an olefin monomer, and optionally an olefin comonomer into a polymerization reactor within the polymerization reactor system, wherein the transition metal-based catalyst composition comprises (a) a transition metal compound;
- (b) an activator-support comprising a solid oxide treated with an electron-withdrawing anion;
- and (c) optionally, a co-catalyst;
- (ii) contacting the transition metal-based catalyst composition with the olefin monomer and the optional olefin comonomer under polymerization conditions to produce an olefin polymer;
- and
- (iii) introducing a synergistic amount of hydrogen and an organozinc compound into the polymerization reactor system to reduce a weight-average molecular weight (Mw) and/or to increase a melt index (MI) of the olefin polymer;
- wherein:
- the synergistic amount of hydrogen and the organozinc compound comprises a hydrogen:organozinc compound molar ratio in a range from about 100:1 to about 25,000:1;
- and
- a Mn of the olefin polymer is substantially unchanged and/or a ratio of Mw/Mn of the olefin polymer is reduced by at least 75%.
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Dependencies are inferred from the claim text.