CATALYSTS FOR OLEFIN POLYMERIZATION
A method for making single-site catalysts useful for olefin polymerization is disclosed. A nitrogen-functional heterocycle is first deprotonated with an alkyllithium compound, followed by reaction of this anionic ligand precursor with about 0.5 equivalents of a Group 4 transition metal tetrahalide i...
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Format: | Patent |
Sprache: | eng ; fre ; ger |
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Zusammenfassung: | A method for making single-site catalysts useful for olefin polymerization is disclosed. A nitrogen-functional heterocycle is first deprotonated with an alkyllithium compound, followed by reaction of this anionic ligand precursor with about 0.5 equivalents of a Group 4 transition metal tetrahalide in a hydrocarbon solvent at a temperature greater than about 10° C. to give an organometallic complex-containing mixture. When combined with exceptionally low levels of an activator (e.g., methyl alumoxane), the mixture actively polymerizes olefins to give polymers with a favorable balance of physical properties, including low density and narrow molecular weight distribution. |
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