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US 5,212,281 AGranted
Process for the preparation of high molecular weight halogenated polycarbonate
AssigneeThe Dow Chemical Company
InventorsSarat Munjal, Clark J. Cummings, Che-I Kao
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Abstract
A process for preparing halogenated polycarbonate wherein the total amount of base, the end pH of the aqueous phase, and the amount of coupling catalyst employed in the reaction are controlled to selected levels.
Claims14
A process for the preparation of halogenated polycarbonate comprising
- (a) contacting a halogenated dihydroxy compound, a base, water and non-reactive organic solvent with a carbonate precursor in a reaction mixture to form a halogenated carbonate oligomer product;
- (b) condensing said halogenated carbonate oligomer product to from polycarbonate product by contacting halogenated carbonate oligomers in a tank reactor with
- (i) further organic solvent;
- (ii) 50 weight parts per million or less of coupling catalyst, based on the weight of all organic solvent present in steps (a) and (b), including any in which the coupling catalyst is dissolved;
- and
- (iii) a further amount of base which, together with the amount of base present in step (a), brings the total moles of base present in steps (a) and (b) per mole of dihydroxy compound to the number 2+4(Y-1)+Q, where Y is the number of moles of carbonate precursor per mole of dihydroxy compound, and Q is about 0.001 to about 0.2;
- and
- (c) recovering a halogenated polycarbonate product.
5 more elements
Dependencies are inferred from the claim text.