| 摘要 |
PURPOSE:To obtain an insulating film-coated magnetic steel sheet excellent in coating stability, weldability and punchability by forming an insulating film contg. thermosetting resin, chromate, reducing agent and a specified amt. of surfactant on magnetic steel sheet. CONSTITUTION:An emulsion contg. a resin such as phenolic resin capable of forming a cross-linked structure, an aq. soln. of chromate or bichromate and a reducing agent such as ethylene glycol are mixed, and 2-15 pts.wt. of surfactant, based on 100 pts.wt. of solid resin, is further added to form an insulating film on the magnetic steel sheet. The solid resin component in the emulsion should have a peak temp. of >=400 deg.C showing the maximum weight change by derivative thermogravimetry when heated at a specified rate. Further, the particle is preferably coated with a chromic acid-resistant resin, e.g. acrylic acid and methyl (meth)acrylate. |
