Insulating varnish and insulated wire formed by using the same
View Patent ↗An insulating varnish usable for an insulating coat of an insulated wire on a conductor with a quadrangular cross section contains polyamide-imide resin varnish and organosilica sol mixed with the polyamide-imide resin varnish. The polyamide-imide resin varnish contains solvent and polyamide-imide resin. The organosilica sol contains dispersion medium and silica particles dispersed in the dispersion medium. Cyclic ketones having boiling point in a range of 130 to 180° C. make up 70 to 100 wt % or more of the dispersion medium.
1. An insulating varnish usable for an insulating coat of an insulated wire on a conductor with a quadrangular cross section, comprising:
a polyamide-imide resin varnish and an organosilica sol mixed with the polyamide-imide resin varnish, the polyamide-imide resin varnish comprising a solvent and a polyamide-imide resin;
wherein the organosilica sol contains a dispersion medium and silica particles dispersed in the dispersion medium, and
at least one cyclic ketone having a boiling point in a range of 130 to 180° C. makes up 70 to 100 wt % of the dispersion medium.
2. The insulating varnish according to claim 1 , wherein the solvent of the polyamide-imide resin varnish contains at least one cyclic ketone having a boiling point in a range of 130 to 180° C.
3. The insulating varnish according to claim 2 , wherein the at least one cyclic ketone of the dispersion medium and the at least one cyclic ketone of the solvent make up 15 to 100 wt % of a total amount of the solvent and the dispersion medium.
4. The insulating varnish according to claim 2 , wherein at least one of cycloheptanone, cyclohexanone, and cyclopentanone is used as the at least one cyclic ketone of the solvent.
5. The insulating varnish according to claim 1 , wherein at least one of cycloheptanone, cyclohexanone, and cyclopentanone is used as the at least one cyclic ketone of the dispersion medium.
6. An insulated wire, comprising:
a conductor with a quadrangular cross section; and
an insulating coat on a surface of the conductor, the insulating coat being formed by using the insulating varnish according to claim 1 .
7. The insulated wire according to claim 6 , wherein a lubricity insulating coat is formed on a surface of the insulating coat.