PRODUCTION OF POLYCARBONATE

摘要

PURPOSE:To recover and reuse an unreacted phenolic compd. effectively with a high purity and thereby improve productivity by subjecting a waste water generated in the reaction to a specific treatment and using the product of the treatment in the reaction in producing a polycarbonate by reacting an aq. alkali soln. of a phenolic compd. with phosgene in the presence of an org. solvent. CONSTITUTION:In producing a polycarbonate by reacting an aq. alkali soln. of a phenolic compd. (e.g. bisphenol A) with phosgene in the presence of an org. solvent (e.g. methylene chloride), the pH of a water waste contg. an unreacted phenolic compd. and generated in the reaction is made lower than 10; the waste water is brought into contact with at least 5vol.% org. solvent (e.g. methylene chloride) to extract the unreacted phenolic compd.; then the org. solvent soln. is brought into contact with an aq. caustic alkali soln. to transfer the phenolic compd. to the alkali soln.; and the alkali soln. is used in the reaction.