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US 6,225,436 B1Granted
Polycarbonate preparation process
AssigneeThe Dow Chemical Company
InventorsJuergen Eiffler, Guenter A. Jueptner
Life of this patent
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Abstract
Disclosed is a polycarbonate composition and process from making same, wherein introduction of a chain terminator and an acyl halide other than phosgene is after at least 25 percent of the hydroxyl groups in the dihydric phenol have been converted to chloroformate groups.
Claims17
A process for producing a polycarbonate composition comprising the steps of:
- a) reacting phosgene and a dihydric phenol until at least 25 percent of the hydroxyl groups in the dihydric phenol have been converted to chloroformate groups,
- b) adding an acyl halide other than phosgene to the reaction mixture after said at least 25 percent of the hydroxyl groups have been converted,
- c) adding a chain terminator to the reaction mixture after said at least 25 percent of the hydroxyl groups have been converted and
- d) completing the polymerization reaction.
1 more element
Dependencies are inferred from the claim text.