INSULATING FILM-FORMING COMPOSITION FOR ELECTROMAGNETIC STEEL PLATE AND FORMATION OF INSULATING FILM ON SAID STEEL PLATE

摘要

PURPOSE:The titled composition, obtained by mixing a specific mixed resin solution with an aqueous solution of an inorganic film-forming material in a specific proportion and capable of giving insulating films having improved insulating properties, etc., with little foaming and good operability by applying to an electromagnetic steel plate. CONSTITUTION:A composition obtained by mixing (A) a mixed resin solution prepared by incorporating (i) an aqueous emulsion obtained by emulsifying and dispersing an organic film-forming resin consisting of an acrylic resin and/or acrylic-styrene based resin and having 2-8pH with (ii) an aqueous dispersion prepared by dispersing an acrylonitrile based resin, containing substantially no emulsifying and dispersing agent and having 6-8pH at a ratio to give 10-90wt% nonvolatile material in the component (ii) based on the nonvolatile materials in the components (i) and (ii) with (B) an aqueous solution of an inorganic film-forming material consisting essentially of a chromate at a ratio to give 15-120pts.wt., based on 100pts.wt. chromate in the component (B) expressed in terms of CrO3, nonvolatile material of the component (A). The above-mentioned composition is applied to an electromagnetic steel plate at 0.4-2.0g/m2 coating ratio and heated at 300-500 deg.C to afford insulating films having improved film characteristics.