Polyamide-imide resins and process of producing them.

摘要

Melt moldable polyamide-imide resins are disclosed which have a glass transition temperature ranging from 120 to 300 DEG C and have molecule ends blocked with an unsubstituted aromatic group or an aromatic group having a substituent not reactive with amines, isocyanates, carboxylic acids and dicarboxylic acid anhydrides, said end-blocking group for instance being derived from phthalic anhydride and benzoic acid. Such resins are obtainable by reacting together an aromatic tricarboxylic acid, anhydride, an aliphatic or araliphatic diisocyanate, an aromatic diisocyanate, and at least one end-blocking agent as aforesaid, the reactants being reacted at a temperature of 180 DEG C or higher in the presence of an alkali metal compound as a catalyst in a dipolar aprotic solvent.