THERMOPLASTIC COPOLYMER COMPOSITION AND ITS PRODUCTION METHOD

PROBLEM TO BE SOLVED: To provide a thermoplastic copolymer composition having superior heat resistance, colorless transparency and moldability and having superior dimensional stability in long-term use under severe conditions; and its production method. SOLUTION: This production method of thermoplastic copolymer composition is characterized in conducting: a step (a first step) for producing copolymer A including an unsaturated carboxylic acid alkyl ester unit (ii) and an unsaturated carboxylic acid unit (iii); a step (a second step) for including a salt consisting of an acid Y with acid dissociation constant of not less than 3 and not more than 7, heat-processing the copolymer A, and performing intramolecular cyclization by dehydration and/or dealcoholization reaction to produce the thermoplastic copolymer B including a glutaric anhydride unit (i) and the unsaturated carboxylic acid alkyl ester unit (ii) represented as general formula (1); and a step (a third step) for adding an acid X with the acid dissociation constant smaller than that of the acid Y by 1.0 or more after the second step. COPYRIGHT: (C)2009,JPO&INPIT