Idemitsu Kosan Company, Limited

Idemitsu Petrochemical Co., Ltd.

Masayuki Takahashi

Noriyuki Kunishi

Yukiko Nagao

Kenji Sasaki

Hiroaki Motegi

Kota Mabuchi

Kazuhiro Sekiguchi

Tomoyuki Yoshida

A method of producing a polycarbonate, including: introducing a tertiary amine into a reaction process; and performing interfacial polycondensation between an alkali aqueous solution of a dihydric phenol and phosgene in the presence of an organic solvent, in which: (i) a portion into which the tertiary amine is introduced comprises at least a tertiary amine storage tank, a tertiary amine supply pipe, and a diluent solvent supply pipe; (ii) the portion further includes a pressure control valve in the tertiary amine supply pipe on an upstream side of a merging portion with the diluent solvent supply pipe; and (iii) when a pressure Pof an inside of the tertiary amine storage tank pressurized by a pressurization gas and a pressure Pin a portion ranging from an outlet of the storage tank to an upstream side of the pressure control valve, a relationship of P&#x2264;Pis satisfied.

Process for producing polycarbonate

Provided is a method of producing a branched polycarbonate, including: a step (a) of subjecting an alkali aqueous solution of a dihydric phenol, phosgene, and a branching agent to a phosgenation reaction in the presence of an organic solvent to provide a reaction liquid; a step (b) of adding the alkali aqueous solution of the dihydric phenol and a polymerization catalyst to the reaction liquid obtained from the step (a) to provide a reaction liquid containing a polycarbonate oligomer; a step (c) of separating the reaction liquid containing the polycarbonate oligomer obtained in the step (b) into an organic solvent phase containing the polycarbonate oligomer and an aqueous phase; and a step (d) of causing the organic solvent phase containing the polycarbonate oligomer separated in the step (c) and the alkali aqueous solution of the dihydric phenol to react with each other to provide a reaction liquid containing the branched polycarbonate, in which a ratio (x/y) of an addition amount of the polymerization catalyst to be added in the step (b), which is represented by x mol/hr, to a chloroformate group amount of the polycarbonate oligomer in the reaction liquid obtained from the step (b), which is represented by y mol/hr, is 0.0035 or more.

Branched polycarbonate production method

Provided is a method of producing a polycarbonate that enables efficient drying of a polycarbonate powder and has no risk of deteriorating the quality of a polycarbonate molded article to be obtained. The method of producing a polycarbonate includes: a step of causing an alkali aqueous solution of a dihydric phenol and phosgene to react with each other in the presence of an organic solvent to produce an organic solvent solution containing a polycarbonate; a powdering step of powdering the organic solvent solution containing the polycarbonate to provide a polycarbonate powder; and a pre-drying step of drying the polycarbonate powder to remove the remaining organic solvent, in which a drying temperature in the pre-drying step is set to a temperature lower than the glass transition temperature of the polycarbonate containing 1.5 mass % of the organic solvent by from 5&#xb0; C. to 15&#xb0; C.

Method for producing polycarbonate

Provided is a method for washing an impurities-containing polycarbonate/organic solvent solution with an aqueous washing solution, which comprises monitoring the viscosity of the mixture dispersion of the polycarbonate/organic solvent solution and the aqueous washing solution, and controlling the blend ratio of the aqueous washing solution in the system on the basis of the relation between the phase condition and the viscosity of the mixture dispersion. In the method of washing a polycarbonate/organic solvent solution with an aqueous washing solution, the amount of the washing solution to be used is reduced, and the mixture dispersion of the two solutions is stabilized at a high level of washing efficiency. The washing method is economical in practical use.

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Taipei, Taiwan

Masayuki Takahashi