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US 6,184,334 B2Granted
Alkali metal salts of oxoacids of sulfur as polymerization catalysts
AssigneeGeneral Electric Company
InventorsPatrick Joseph McCloskey, Timothy Brydon Burnell, Paul Michael Smigelski, Jr.
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Abstract
The present invention relates to a method for the preparation of polycarbonate comprising preparing a polycarbonate by a melt process by reacting a diphenol and a diaryl carbonate in the presence of a catalytically effective amount of one or more alkali metal salts of oxoacids of sulfur.
Claims22
A method for the preparation of polycarbonate by the melt process comprising
- a) heating, in one or more stages, a mixture comprising a diphenol and a diarylcarbonate;
- and
- b) introducing into the mixture of a), in the same stage or different stages a catalytically effective amount of one or more alkali metal salts of oxoacids of sulfur.
A method for the preparation of polycarbonate comprising
- a) heating, in one or more stages, a mixture comprising a diphenol and a diarylcarbonate;
- and
- b) introducing into the mixture of a), in the same stage or different stages 1) a catalytically effective amount of one or more alkali metal salts of oxoacids of sulfur and 2) a catalytically effective amount of a base selected from the group consisting of TMAH, TBPH and a mixture thereof.
A method of reducing the Fries content of a polycarbonate comprising
- a) heating, in one or more stages, a mixture comprising a diphenol and a diarylcarbonate;
- and
- b) introducing into the mixture of a), in the same stage or different stages a catalytically effective amount of one or more alkali metal salts of oxoacids of sulfur.
A method for the preparation of polycarbonate comprising
- a) heating, in one or more stages, a mixture comprising BPA and diphenylcarbonate;
- and
- b) introducing into the mixture of a), in the same stage or different stages a catalytically effective amount of sodium metabisulfite.
Dependencies are inferred from the claim text.