| 摘要 |
PURPOSE:To eliminate voids and to improve the performance of an electrical insulator by a method wherein a mica leaf is impregnated with a solventless low-viscosity resin and then with another solventless resin having higher viscosity than said low-viscosity resin and dried by heating, and a preimpregnated mica tape thus prepared is wound on a conductor and formed under heat and pressure. CONSTITUTION:A composite mica sheet 1 having a density of 160g/m<2> and a glass cloth 2 with a thickness of 45mum are drawn out in superposition. Then, low-viscosity resin 4 of a first resin tank 3 is applied on the surface of the glass cloth through the intermediary of a first coating roller 5 and sucked up from said surface, and thus the sheet is impregnated with the resin. Thereafter it is impregnated in the same way with high-viscosity resin 7 kept at the temperature of about 60 deg.C in a second resin tank 6, through the intermediary of a second coating roller 8. Next, the sheet is passed through a heating furnace 9 so as to be dried by heating to such a degree that it is not sticky while the resin is not set completely, and then it is wound on a winding roller 10. A mica tape manufactured in this way is wound on a conductor and formed under heat and pressure into an electrically-insulated coil. |
