Patent ID: 8759472

Claim:
A polyamide-imide resin insulating paint, including a low permittivity polyamide-imide resin containing no halogen element in its molecular chain which is dissolved in a polar solvent, wherein: the low permittivity polyamide-imide resin is made by mixing an aromatic imide prepolymer, which contains an aromatic diamine component (E) consisting of an aromatic diamine having three or more benzene rings in a monomer and an acid component consisting of an aromatic tricarboxylic anhydride (C) and an aromatic tetracarboxylic dianhydride (D), with an aromatic diisocyanate component (B) consisting of an aromatic isocyanante having two or less benzene rings in a monomer, having a compounding ratio between C and D of C/D=95/5 to 60/40, a compounding ratio among E, C and D of E/(C+D)=51/100 to 70/100, and a ratio M/N between a molecular weight (M) of the polyamide-imide resin per repeat unit and an average number (N) of amide groups and imide groups is equal to or more than 200.