PROCESS FOR PREPARING POLYCARBONATE PREPOLYMER AND PROCESS FOR PREPARING HIGH-MOLECULAR POLYCARBONATE Russian patent published in 1995 - IPC

FIELD: building industry. SUBSTANCE: the polycarbonate prepolymer is prepared by interphase condensation of bisphenol A and phosphen in the presence of an aqueous solution of sodium hydroxide, methylene chloride and tert-butylphenol. The starting components are passed through fixed mixers connected with a system of tubes a mixture of products is kept in the system of tubes till a mixture of products is obtained in the form of a coarse dispersion and an additional amount of an aqueous solution of sodium hydroxide is introduced and the procedure of mixing and keeping the mixture is repeated till a polycarbonate prepolymer having a mean molecular weight of 4380-11200 is formed. The process comprises cooling the reaction mixture to 25-50 C after adding thereto an additional amount of an aqueous solution of sodium hydroxide. The resulting polycarbonate prepolymer is polycondensed in the presence of triethylamine and a highly molecular polycarbonate is isolated. EFFECT: more efficient process. 3 cl, 2 tbl