| 摘要 |
PURPOSE:To form electrically insulating film excellent in punchability, weldability and heat resistance, by painting a treating soln. composed of aqueous amide-imide resin, chromate or dichromate on the surface of an electrical sheet, then by bakng said painted electrical sheet. CONSTITUTION:On the surface of an electrical sheet for small revolving machines etc. is formed heat resistant elecrically insulating film. A treating soln. for forming said film is made by mixing 100pts.wt. nonvolatile matter of aqueous amide-imide resin with 50-200pts.wt. at least one member among chromates, dichromates. Chromates, dichromates composed of oxide MO of one or more member among divalent metals such as Mg, Ca, Zn etc., and CrO3 in 0.4-1.0 molar ratio MO/ CrO3 is used. The fluid is painted on the electrical sheet with grooved rubber roll etc. so as to form film of 2-8g/m<2> after baking. Said electrical sheet is baked at 200-400 deg.C sheet temp. for 30sec-5min. Hereby electrically insulating sheet having film excellent in punchability, weldability,and heat resistance is manufactured. |
