Abstract: A heat resistant composition comprising a mixture of (a) a polyurethane or a modified polyurethane and (b) a bismaleimide oligomer, in which the bismaleimide oligomer is in an amount of about 1 to 35 percent by weight based on overall solid contents. The polyurethane is formed by reacting a diisocyanate-containing compound with a dihydroxy diol-compound. Then the polyurethane is reacted with a trimellitic anhydride, a diacid or a mixture thereof to form the modified polyurethane. The bismaleimide oligomer is formed by reacting a bismaleimide resin with a barbituric acid or a derivative thereof.

Abstract: A method for preparing a polyamide-imide-modified polyurethane varnish composition for coating a conductive wire to form a varnished wire. The method comprises the steps of: (a) preparing a first intermediate reaction product, which is an isocyanate compound, (b) preparing a second intermediate reaction product, which is a hydroxy compound, and (c) mixing the first and second intermediate reaction products with a diluent to form the polyamide-imide-modified polyurethane varnish composition. The first intermediate reaction comprises the steps of: (I) preparing a first reaction mixture containing a phenol or a derivative of phenol, a diisocyanate, and a dihydroxy compound in a first organic solvent, and reacting the first reaction mixture at room temperature; (ii) adding a diacid compound or trimellitic anhydride or mixture thereof to the first reaction mixture, and reacting at 100.degree..about.140.degree. C.

Abstract: Disclosed is a novel linear urethane-amide-imide copolymer composition obtained from first reacting X mols of diol compound, which had been dissolved in an inert organic solvent, with Y mols of diisocyanate compound at room temperature to produce an intermediate reaction product, followed by reacting the intermediate reaction product with Z mols of trimellitic anhydride at elevated temperatures, wherein Y is greater than X (i.e., the amount of diisocyante groups is in excess) and approximately equals the sum of X plus Z. The polyurethane copolymer composition obtained from this process contains urethane, amide and imide groups on the polymer backbone, exhibits excellent mechanical and electric properties and heat resistance, and does not suffer from the phase separation problems observed from polyurethane-polyamideimide blends.