Polyester imide resin based varnish for low-permittivity coating film

Abstract

Provided are a varnish mainly containing a polyester imide and capable of forming a low-permittivity insulating layer, as well as an insulated electronic wire achieving low permittivity by using the varnish. The varnish mainly contains a polyester imide resin obtained by reacting a carboxylic acid including a dicarboxylic acid, or an anhydride or alkyl ester thereof (carboxylic acid or derivative thereof), an alcohol, and a diamine compound with one another. In the varnish, adjustment is made such that a molar ratio (OH/COOH) of hydroxyl groups of the alcohol to carboxyl groups of the carboxylic acid or derivative thereof becomes 1.9 or less or such that a content of highly polarized imide groups per unit amount of polyester imide chain is reduced by increasing molecular weights of the raw material monomers.

Dependencies are inferred from the claim text.