| 摘要 |
PROBLEM TO BE SOLVED: To provide an insulation film agent which enables the production of a nonoriented silicon steel sheet having an excellent appearance, weldability, corrosion resistance, blanking properties, adhesion or the like in a thinly coated film. SOLUTION: The insulation film agent consists of 10 to 90 pts.mass colloidal silica having a specific surface area of >=350 m<2> /g as SiO2 , and 5 to 50 pts.mass CrO3 to 100 pts.mass of primary phosphate consisting of Mg, Ca and Al containing one or two kinds of primary phosphate of Al and Ca as solid contents. If required, a 0.1 to 3.0 pts.mass carboxylic surfactant or 2 to 10 pts.mass boric acid is added and blended therein, and its surface contact angle is <=40 degrees.
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