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US 6,723,823 B2Granted
Method of polycarbonate preparation
AssigneeGeneral Electric Company
InventorsPatrick Joseph McCloskey, Warren William Reilly, Brian James Grimmond
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AssigneeGeneral Electric Company
InventorsPatrick Joseph McCloskey, Warren William Reilly, Brian James Grimmond
Estimating the term…
Mixed alkali metal salts of phosphoric acid in combination with a co-catalyst such as tetramethylammonium hydroxide (TMAH) are excellent transesterification catalysts for use in the preparation of polycarbonate from bisphenol A and diphenyl carbonate. The mixed alkali metal phosphate salts were shown by kinetic measurements made on a model system composed of p-tert-octylphenol and bis(p-cumylphenyl) carbonate to be inherently more potent catalysts than salts of phosphoric acid comprising a single alkali metal ion. In addition to providing higher rates of polymerization, the new catalysts were shown to provide polycarbonates containing reduced levels of Fries rearrangement product relative to polymerization reactions catalyzed by conventional catalyst systems such as sodium hydroxide together with TMAH co-catalyst.
A method of preparing polycarbonate, said method comprising reacting under melt polymerization conditions in the presence of a transesterification catalyst at least one dihydroxy aromatic compound and at least one diaryl carbonate, said transesterification catalyst comprising at least one mixed alkali metal salt of phosphoric acid and at least one co-catalyst, said co-catalyst comprising a quaternary ammonium salt, a quaternary phosphonium salt or a mixture thereof.
A method for the preparation of polycarbonate, said method comprising contacting at least one dihydroxy aromatic compound with at least one diaryl carbonate under melt polymerization conditions in the presence of a transesterification catalyst, said transesterification catalyst comprising at least one mixed alkali metal salt of phosphoric acid and at least one co-catalyst, said co-catalyst comprising a quaternary ammonium salt, a quaternary phosphonium salt or a mixture thereof, said contacting being carried out in at least two stages.
A method of making polycarbonate said method comprising contacting diphenyl carbonate with bisphenol A in the presence of a transesterification catalyst at a temperature in a range between about 180° C. and about 310° C. and a pressure in a range between about 760 and about 1 torr to afford a product bisphenol A polycarbonate, said transesterification catalyst comprising at least one mixed alkali metal salt of phosphoric acid and at least one co-catalyst, said co-catalyst comprising a quaternary ammonium salt, a quaternary phosphonium salt, or a mixture thereof.
Dependencies are inferred from the claim text.