FORMATION OF INSULATING FILM ON ELECTRICAL STEEL SHEET

摘要

PURPOSE:To obtain a uniform film having improved adhesive strength by adding a prescribed percentage of a surfactant to a treating liq. for forming a film on a magnetic plate so as to form a stable resin emulsion. CONSTITUTION:A surfactant is added to a treating liq. contg. chromic anhydride and/or dichromate and a synthetic resin emulsion by 2 30wt% of the amount of solid matter in the synthetic resin. The surfactant added is a block copolymer of propylene oxide with ethylene oxide or polyoxyethylene alkyl phenyl ether as a nonionic surfactant. A magnetic plate such as an electrical steel sheet is treated with the treating liq. contg. the surfactant to form an insulating film.