Electromagnetic steel plate insulation coating and a method of forming a magnetic steel sheet insulation coating composition for forming

摘要

PURPOSE:To form the film excellent in coating and insulating properties by using the mixed composition of an aq. emulsion of a polymer contg. a carboxylic acid component, the fine powder of an methacrylic acid polymer and an inorg. film forming material. CONSTITUTION:A carboxylic acid polymer contg. 56-97wt.% alkyl methacrylate, 3-7% ethylenic unsaturated carboxylic acid and 0-37% vinyl compd. other than the above-mentioned components and having =0.5mum average particle diameter is dispersed in an aq. medium to prepare an emulsion A having 40-70 deg.C lowest film forming temp. and =10ml ability. The emulsion A and the fine powder B of a metachrylic ester-based polymer having =80 deg.C lowest film forming temp. are mixed so that B is controlled to 10-90% based on the nonvolatile component of A plus B. The mixed resin soln. and an aq. soln. consisting essentially of a chromate are mixed so that 100 parts of the chromate expressed in terms of CrO3 is mixed with 15-120 parts of the nonvolatile matter in the mixed resin soln. The composition is applied on a magnetic steel sheet and heated to about 300-500 deg.C to form an insulating film at about 0.4-6.0g/m2.