Abstract: Aromatic diamines having a carboxylic acid group and various other diamines are reacted with aromatic tetracarboxylic dianhdyrides in organic polar solvents to provide polyimides. Polyimide compositions for electrodeposition which comprise the neutralized salts of the polyimides, water and poor solvents for the polyimides have good keeping quality and when electrodeposited on electrically conductive materials, can form polyimide coats that have high levels of appearance, smoothness and denseness while exhibiting good physical and chemical characteristics in such aspects as heat resistance, electrical insulation and chemical resistance.

Abstract: Polyimide soluble in an organic polar solvent was prepared by heating the solution in the presence of a binary catalyst having low boiling point. Block copolyimides consisting of more than three components were prepared by the sequential addition process in the presence of the binary catalyst. Polyimide resins were prepared without the separation of polyimides and catalysts because of evaporating consequently catalysts and solvent. The binary catalyst comprise one compound selected from .gamma.-valerolactone and crotonic acid, and one compound selected from pyridine and N-methylpyrrolidone.