PURPOSE: To obtain a heat-resistant resin which provides phase separation-free varnishes which, when baked, from films having uniform gloss, by reacting, by heating, a specified polyamide-imide resin with an alcohol component and an acid component.
CONSTITUTION: A heat-resistant resin is produced by reacting (a) an isocyanate ring-containing polyisocyanate (e.g., one prepared by trimerizing tolylene diisocyanate) with (b) a diisocyanate (e.g., 4,4'-diphenylmethane diisocyanate), (c) a monoimidodicarboxylic acid of the formula (wherein n is 1W10), and (d) a tricarboxylic anhydride (e.g., trimellitic anhydride) [component (a) is used in an amount of 0W30 equivalent %, based on the total number of equivalents, and component (c) is used in an amount of 10W39 equivalent %, based on the total acid component] to obtain a polyamide-imide resin, and then, after adding an alcohol component (e.g., ethylene glycol) and an acid component (e.g., terephthalic acid), reacting the resulting reaction mixture by heating.
OKADA TAISUKE
SHINPO YASUSHI
