Dephenolizing process for production of high-quality polycarbonate grade bisphenol A
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United States of America Patent
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May 13, 1997
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N/A
app pub date -
Sep 29, 1995
filing date -
Feb 16, 1993
priority date (Note) -
Expired
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Abstract
A process for producing high-quality polycarbonate grade bisphenol A directly by removing phenol from the adduct crystal of bisphenol A with phenol via a gas-solid reaction at low temperature comprises directly feeding the adduct crystal into a vacuum or pneumatic dephenolizing device under vacuum a inert gas stream, controlling the temperature of the adduct crystal below its melting point, decomposing the adduct crystal into gas phase and solid phase, removing the gas phase phenol and condensing phenol for recovery, well leaving the rest being the desirable bisphenol A. The process possesses easy operation, short procedure, low energy consumption, and high purity and good color of bisphenol A obtained. Bisphenol A produced according to the process of the invention may be used as the raw material for producing polycarbonates for optical use.
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