Mitsubishi Chemical Corporation

Mitsubishi Petrochemical Company Limited

Junji Takano

Masuzo Yokoyama

Masami Hasegawa

Yukiko Tatsukawa

Kazuhide Takakura

Fumio Keitoku

A process for producing an aromatic polycarbonate is described, which comprises melt-polycondensing an aromatic diol compound with a diaryl carbonate compound in the presence of an interesterification catalyst, said interesterification catalyst comprising a quaternary phosphonium salt compound represented by formula (II): ##STR1## wherein R.sup.3, R.sup.4, R.sup.5, and R.sup.6 each independently represent an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and X.sup.l- is an anion selected from the group consisting of a carbonate ion, a phosphate ion, and a tetrahydroxyboron ion, with the letter l indicating the valency of X.

Process for producing aromatic polycarbonate

A process for producing an aromatic polycarbonate having a weight average molecular weight of from 7,000 to 60,000 is disclosed, comprising melt polycondensing an aromatic diol compound (e.g., bisphenol A) and a diaryl carbonate compound (e.g., diphenyl carbonate) in the presence of a combination of (a) an alkali metal compound and (b) a phosphonium hydroxide compound (e.g., tetraethylphosphonium hydroxide) as an interesterification catalyst. The aromatic polycarbonate has improved heat resistance and hue.

A process for producing an aromatic polycarbonate with improved heat resistance comprising melt polycondensing an aromatic diol compound and a carbonic acid diester compound in the presence of an interesterification catalyst and in the co-presence of an organosilicon compound.

An aromatic polycarbonate of improved color value and high molecular weight is obtained by the addition of phosphorous acid and/or a phosphorous ester to the melt polycondensation reaction medium containing aromatic diol, carbonate diester and a metal-containing compound as ester interchange catalyst during the polycondensation reaction

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Mie, Japan

Junji Takano