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US 6,855,795 B2Granted
Catalyst removal process
AssigneeHuntsman Petrochemical Corporation
InventorsJohn H. Clements, Howard P. Klein, Kenneth M. Hillman
Life of this patent
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Abstract
The present invention provides a process for producing polycarbonates in the presence of one or more alkali metal or alkaline-earth metal catalysts, and subsequently removing the catalyst residues by chelation, to yield a clear polycarbonate product that is free from catalyst residues, and is thus suitable for use as a binding material in the ceramics industry where residual amounts of catalysts in the binder are burdensome.
Claims8
A process for producing a polycarbonate having the structure:
- in which n is any number between about 5 and 50, R is any C1 to C20 alkyl group, whether straight-chain, cyclic, or branched, comprising the steps of:
- a) reacting a reaction mixture comprising an aliphatic diol according to the formula:
- HO—R—OH in which R is any C1 to C20 alkyl group, whether straight-chain, cyclic, or branched and a linear organic carbonate having the formula:
- in which R1 and R2 may independently be alkyl groups ranging from C1 to C4, linear or branched, at a temperature of 60° C. to 180° C. in the presence of a catalyst selected from the group consisting of:
- one or more alkali or alkaline earth metal alkoxide, hydroxide, carbonate, or carboxylate salts, or mixtures of any of the foregoing;
- b) supplying heat to said reaction mixture to cause distillation of alcohol by-product(s) produced from step a) above until said reaction mixture reaches a termination temperature of at least 150° C. to provide a semi-stripped crude product;
- c) contacting said semi-stripped crude product from step b) with a chelating agent;
- to form a slurry;
- and
- d) filtering said slurry from step c) to provide a clear liquid.
7 more elements
Dependencies are inferred from the claim text.