Heat Resistant Magnet Wire Insulation Based on Acrylic Enamels

New heat resistant magnet wires having F - H thermal life can be made by overcoating suitable conventional enamels on acrylonitrile copolymer based enamel. Heat resistant glutaroimide and gluaroimidine ringtruc structures were found to be formed during baking and thermal aging for dual coated acrylic enamels, even in an oxidative environment. The ratio of glutaroimide ring formation to oxidation reaction rates by oxygen permeated through the overcoated layer, increased with temperature. Details of the mechanism of the formation of the heat resistant structures was studied. The thermal and mechanical properties were found to improve by formation of thermostable heterocyclic rings during baking and thermal aging.