PURPOSE: To prepare a water-soluble electrical insulating paint having excellent appearance, at a low cost, by adding a specific amount of an acrylonitrile-acrylic acid copolymer to a solution obtained by neutralizing a reaction product of a specific polyester or a imide and a carboxylic acid having a valency of ≥3.
CONSTITUTION: A polyester or a polyester imide having reactive redidual hydroxyl group is made to react with a carboxylic acid having a basicity of ≥3 (pref. tetracarboxylic acid dianhydride) by adding the carboxylic acid in an amount of pref. 5W30 equivalent % of the whole acid component, and the product is neutralized with a base (e.g. aqueous ammonia) to obtain an aqueous solution of a polyester resin or a polyester imide resin. The objective insulating paint is obtained by adding an acrylonitrileacrylic acid copolymer to the solution. The amount of the copolymer is 0.5W15(wt)%, pref. 5W10% of the total resin content.
WAKE MISAO
FUKUSHIMA MASATADA
HIRANO TATSUMI
