COATING COMPOSITION FOR INSULATION LAYER AND METHOD FOR FORMING INSULATION LAYER ON NON-ORIENTED SILICON STEEL SHEETS USING THE SAME

摘要

PURPOSE: A coating composition for insulation layer, and a method for forming an insulation layer with superior thermal resistance by stress relief annealing on non-oriented silicon steel sheets using the same is also provided. CONSTITUTION: The coating composition for insulation layer comprises (a) a phosphate solution; (b) 13.9 to 70.2 g of emulsion acryl-based resin (based on the solid weight); (c) 1.1 to 6.8 g of colloidal alumina; (d) 0.25 to 1.95 g of silane coupling agent; (e) 5.1 to 23.8 g of zinc nitrate, based on 100 g of phosphoric acid contained in the phosphate solution, wherein the phosphate solution is monobasic magnesium phosphate or monobasic aluminum phosphate prepared by blending phosphoric acid with magnesium hydroxide or aluminum hydroxide. The method for forming an insulation layer on non-oriented silicon steel sheets includes the steps of applying the coating composition per one side of a non-oriented silicon steel sheet in a thickness of 0.8 to 4.2 micrometers; and annealing the non-oriented silicon steel sheet at 550 to 750 deg.C for 14 to 45 seconds.