Aqueous polyester insulating lacquers - with good electrical and mechanical properties, for coil wires

摘要

The lacquers are made by substantially complete reaction of (1) a-equivs. di- or tri-carboxylic acids, or derivs. with a gp. attached to -CO- which is easily substd. by alkoxy, 95 equiv. % being an aromatic dicarboxylic acid or deriv. (2) b-equivs. primary diol, and (3) c-equivs. aliphatic alcohol with =3-OH gps. in proportions such that a/(b+c) (1+c/b+c) =1 and a/(b+c) =0.4. The prod. is reacted with (4)d-equivs. tetracarboxylic acid or deriv. in amt. such that the ratio of d to (b+c-a) is 0.5-2. The polyester is dispersed in water contg. ammonia or an organic amine. Pref. (1) contains =95 equiv. % dimethyl terephthalate and =5 equiv. % trimethyl cyanurate or dicarboxylic acid or deriv. contg. an imide, hydantoin or imidazopyrrolone ring. The lacquers give off no harmful fumes on baking and gives films with good electrical and mech. props.