| 摘要 |
PURPOSE:To obtain excellent insulation resistance, excellent heat resistance and high interlayer insulation resistance by a method wherein a treatment solution is composed by mixing emulsion type resin and organic reducing agent into a specific chromate solution and this treatment solution is applied on the surface of a metal plate and baked. CONSTITUTION:A treatment solution is composed by mixing emulsion type resin and organic reducing agent into a chromate solution and this treatment solution is applied on the surface of a metal plate and baked to form an electrical insulating film. In the chromate solution, at least one of aluminum compounds and at least one of oxide, hydroxide and carbonate of diadic metal, which are produced by neutralizing reaction with isolated chromic acid and dissolved, exist as Al<3+> and Me<2+> (where Me<2+> means single or mixed ion of diadic metal) and mol ratio of Al<3+>/Me<2+>/CrO3 is within 0.4-0.7. The aluminum compound, whose chromate produced by neutralizing reaction is water-soluble, does not contain inorganic anion other than carbonic acid anion and alkaline metal cation as its components. |
