PRODUCTION OF POLYAMIDE-IMIDE BASED ENAMEL-PROCESSING VARNISH AND ENAMEL-PROCESSING VARNISH PRODUCED THEREBY

摘要

PURPOSE: To obtain a varnish showing high storage stability and low viscosity and providing an insulating enamel holding good physical and chemical characteristics by condensing an aromatic diisocyanate and an aromatic polycarboxylic acid in N-methylpyrrolidone and separating the condensate in a powder form to dissolve the same in other solvent. ;CONSTITUTION: An aromatic diisocyanate or a diamine corresponding thereto and an aromatic polycarboxylic acid having at least three carboxyl functional groups or an anhydride, ester or halide of an acid corresponding thereto are condensed in a state dissolved in N-methylpyrrolidone. Next, N- methylpyrrolidone is removed to separate a polyamide-imide from the reactive soln. in a powder state. Subsequently, this polyamide-imide powder is dissolved in a solvent comprising an aprotic polar solvent at least a part of which is other than N-methylpyrrolidone to obtain the objective varnish.;COPYRIGHT: (C)1993,JPO