PROCESS FOR PREPARING AN INSULATING MATERIAL FOR ELECTRIC MACHINES

The invention relates to a process for preparing an insulating material for electric machines. According to the invention, the process consists in submerging a 0.20 mm-thick duplex foil material of polyethylene terephthalate consisting, on one face, of non-woven fibres and, on the opposite face, of a heat-setting adhesive impregnated with a resin of high thermal resistance into an air oven, for 24 h, in a mixture consisting of alkydo-epoxy-melamine electro-insulating impregnation lacquer, 0.5% sterically hindered phenol antioxidant and 5% SiOnanoparticles, at heating times of 72, 168 and 240 h, after which the impregnated material is subjected to γ radiation in a dose of 1 kGy/h, for 100 h, to result in an insulating material of thermo-oxidative stability expressed by chemiluminescence emission intensity corresponding to a temperature of 180°C.