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US 5,288,837 AGranted
Preparation of polycarbonate with subsequent addition of chain terminator and base
AssigneeThe Dow Chemical Company
InventorsSarat Munjal, Thomas M. Wardlow, Andrew F. Hall
Life of this patent
Estimating the term…
Abstract
A process for preparing polycarbonate wherein a chain terminator is added to the reaction mixture after substantial reaction of a carbonate precursor, a coupling catalyst is added to the reaction mixture after substantial reaction of the chain terminator, and base is added to the reaction mixture after reaction mixture after substantial reaction of the chain terminator in an amount sufficient to give a negative chloroformate test.
Claims6
A process for preparing polycarbonate comprising
- (a) forming a carbonate oligomer by contacting a carbonate precursor with a solution containing a dihydroxy compound, water, a solvent capable of dissolving a carbonate precursor, and a base,
- (b) admixing a chain terminator with said solution after said carbonate precursor has been substantially completely reacted with said solution,
- (c) forming a polycarbonate by admixing with said solution, after said chain terminator has been substantially completely reacted therewith, sufficient base to impart to said solution a negative chloroformate test,
- (d) recovering a polycarbonate product from said solution.
1 more element
Dependencies are inferred from the claim text.