High thermal resistant insulating varnish based on natural resin shellac and alkyd/polyamide resins

摘要

Insulating varnish compositions have been developed based on blends of solutions of natural resin shellac and synthetic resins viz., alkyd/polyamide resins, producing films having high dielectric strength, thermal resistance (～230°C) and also resistance towards humidity/ water besides other desirable properties. The film properties of such blends have so far been not reported. The method of preparation has been made simple. The varnish compositions satisfy the basic requirements of insulating varnishes as per BIS specifications.