METHOD OF PRODUCING POLYCARBONATE Russian patent published in 1994 - IPC

FIELD: chemical industry. SUBSTANCE: novel method of producing polycarbonate included the following steps. First, researchers prepared admixture of organic solvents, that is, methylenechloride and chlorobenzene taken in mass ratio of (20 to 80) : (20 to 80) and then added with diphenylolpropane, phenol and 46-percent aqueous solution of NaOH with stirring. Thus prepared suspension was continuously admitted in reactor. Distilled water and gaseous phosgene were fed in the same reactor where temperature was maintained between 46 and 54 C. Mass ratio of diphenylolpropane, water, solvent, and sodium hydroxide was (12 to 34.3) : (5 to 14.4) : (38.6 to 78.5) : (4.5 to 12.7) respectively. Before polycondensation was started, organic solvent having temperature of +25 to -45 C was introduced. Polycondensation was conducted in the presence of catalyst. Polycarbonate solution was washed off in cascade of separator- extractors, evaporated in thin-film evaporator and granulated using vacuum extruder by method already known in the art. EFFECT: refined method of producing polycarbonate. 3 tbl