Electrical machine windings insulating compsn. - comprising mixt. of epoxy! resins and mixt. of polyester and phenolic hardeners

摘要

The parent patent described a binder for insulating electrical machine windings and comprising a mixt. of 3 of th3 following 4 components:- (a) Bisphenol A epoxy resin of epoxy equiv. 174-195, (b) novolak epoxy resin with an organic acid catalyst, with a theoretical chain of 5-8 links, decanted and washed at the methylolphenol stage and (d) resorcinol-formaldehyde condensate catalyst obtd. by reacting 2 moles resorcinol and 1 mole HCHO, with an organic acid catalyst. The were used in amts. of 60-120 pref 90% of the stoichiometric amt. and the organic acid catalyst of the PF condensate was also the catalyst for the polymsn. reaction between epoxy resins and hardeners and was present in the binder in amts. of 0.1-6 wt.% of the hardeners. In the addition the resins and hardeners of the parent patent are copolymerised with a complex long chain epoxy resin formed by the polyether deriv of an organic polyhydroxy cpd. contg. epoxy gps, and with an acid polyester hardener of low mol. wt. formed by reacting polyalcohol and a dicarboxylic acid and contg. free COOH gps. The binder has improved low temp. resilience, allowing the windings to resist high low temp. stress while preserving the high temp. properties or improving them, esp. ageing resistance above 155 deg.C.