Patent Number: 6,252,036

Title: Process for producing polycarbonate resin

Abstract: The purpose of this invention is to produce a stabilized terminal-blocked polycarbonate resin with a limited number of the terminal hydroxy groups having excellent thermal stability, color stability and hydrolysis resistance by an industrially advantageous method using a terminal blocking agent. In the production of a polycarbonate by the melt-polycondensation of an aromatic dihydroxy compound with an aromatic carbonic acid diester in the presence of a polycondensation catalyst, a terminal blocking agent expressed by the following formula (1) ##STR1## [in the formula, R.sup.1 is chlorine atom, methoxycarbonyl group or ethoxycarbonyl group; R.sup.2 is an alkyl group having a carbon number of 1 to 30, an alkoxy group having a carbon number of 1 to 30, an aryl group having a carbon number of 6 to 30 or an aryloxy group having a carbon number of 6-30] is added after the melt-polycondensation to the system in an amount of 0.3 to 4 mol-equivalent based on the hydroxy terminal group amount of the polycarbonate at 200 to 350.degree. C. under a pressure of 1,013 hPa (760 mmHg) or below for 0.1 second or longer and, thereafter, a stabilizer is added and kneaded into the system at 200 to 350.degree. C. under a pressure of 1.333.times.10.sup.5 hPa (10.sup.5 mmHg) or below for 0.1 second or longer.

Inventors: Hatono; Kazuki (Yamaguchi, JP), Kaneko; Hiroaki (Yamaguchi, JP), Sawaki; Toru (Yamaguchi, JP), Sasaki; Katsushi (Yamaguchi, JP)

Assignee: Teijin Limited

International Classification: C08G 64/14 (20060101); C08G 64/30 (20060101); C08G 64/00 (20060101); C08G 063/78 ()

Expiration Date: 06/26/2018