SILOXANE-CONTAINING POLYAMIDE-IMIDE, METHOD FOR PRODUCING THE SAME, AND VARNISH CONTAINING THE SAME

PROBLEM TO BE SOLVED: To obtain a siloxane-containing polyamide-imide which is soluble in a solvent, does not need to be filtered and purified, has a high molecular weight, and has excellent film forming properties. SOLUTION: The siloxane-containing polyamide-imide is obtained by reacting a mixture of (A) a diamine having at least three aromatic rings with (B) a siloxanediamine (A/B=99.9/0.1 to 0.1/99.9 mol ratio) with trimellitic anhydride in a molar ratio [the ratio of the number of moles of (A+B)/the number of moles of trimellitic acid]=1/2.05 to 1/2.20 at 50 to 90°C in an aprotic polar solvent, adding an aromatic hydrocarbon azeotropically distillable with water in a weight ratio of 0.1 to 0.5 to the aprotic polar solvent, reacting the mixture at 120 to 180°C to form a mixture containing an aromatic diimidedicarboxylic acid and a siloxane diimidedicarboxylic acid, and reacting the mixture with an isocyanate. COPYRIGHT: (C)2004,JPO