Insulated wire, method of producing insulated wire, coil, rotating electrical machine, and electrical or electronic equipment

1. An insulated wire having at least one layer of coating of the wire, comprising a thermosetting resin layer, at the outer periphery of a conductor,

wherein the thermosetting resin layer is comprised of thermosetting resin layers having a laminated structure formed by coating and baking a thermosetting resin varnish; and wherein, in said laminated structure, an innermost layer having contact with the conductor comprises a thermosetting resin having an imide bond and is a layer having an average thickness of more than 5 μm and 9 μm or less;

wherein the thermosetting resin having an imide bond comprises a polyimide, a polyetherimide, or combinations thereof; and

wherein the conductor is a rectangular conductor whose cross-sectional shape perpendicular to the longitudinal direction thereof is rectangular; and wherein, in the thickness of the innermost layer having contact with the conductor and locating on 4 sides that constitute a rectangle as the cross-sectional shape of said conductor, a thickness on both ends of at least one side excluding corners of the conductor is 1.2 to 2.0 times a thickness on a central part of said side.

2. The insulated wire according to claim 1 , wherein a ratio of an average thickness of the innermost layer having contact with the conductor to a total thickness of the thermosetting resin layers is from 5 to 10%.

3. The insulated wire according to claim 1 , wherein the conductor is a rectangular conductor whose cross-sectional shape perpendicular to the longitudinal direction thereof is rectangular; and wherein a thickness of the innermost layer having contact with the conductor and locating on at least one corner portion of 4 corners that constitute a rectangle as the cross-sectional shape of said conductor is thinner than an average thickness on a side portion of the conductor.

4. The insulated wire according to claim 1 , wherein the laminated structure of the thermosetting resin layers has laminated layers composed of at least 2 layers each having a thickness of 5 μm or less at the outer periphery of the innermost layer having contact with the conductor.

5. The insulated wire according to claim 1 , wherein a total thickness of the thermosetting resin layers is from 30 to 130 μm.

6. The insulated wire according to claim 1 , further comprising at least one thermoplastic resin layer having a thickness of 30 to 130 μm on the thermosetting resin layers.

7. A coil, comprising one or more of the insulated wire according to claim 1 .

8. A rotating electrical machine, comprising the coil according to claim 7 .

9. An electrical or electronic equipment, having the coil according to claim 7 .

10. A method of producing an insulated wire having at least one layer of coating of the wire, comprising a thermosetting resin layer at the outer periphery of a conductor,

comprising a coating and baking step of repeating 2 times or more a step of coating and baking the same or different kind of a thermosetting resin varnish at the outer periphery of the conductor,

wherein at a first step of coating and baking the thermosetting resin varnish, a varnish of a thermosetting resin having an imide bond is used to form a layer having an average thickness of more than 5 μm and 9 μm or less, and then a step of coating and baking a varnish of a thermosetting resin that is the same or different from said thermosetting resin having an imide bond is carried out, to thereby form a thermosetting resin layer having a laminated structure of 2 or more layers;

wherein the thermosetting resin having an imide bond comprises a polyimide, a polyetherimide, or combinations thereof; and

wherein the conductor is a rectangular conductor whose cross-sectional shape perpendicular to the longitudinal direction thereof is rectangular; and wherein, in the thickness of the innermost layer having contact with the conductor and locating on 4 sides that constitute a rectangle as the cross-sectional shape of said conductor, a thickness on both ends of at least one side excluding corners of the conductor is 1.2 to 2.0 times a thickness on a central part of said side.

11. The method of producing the insulated wire according to claim 10 , further forming a thermoplastic resin layer by extrusion-forming of a composition comprising a thermoplastic resin on the thermosetting resin layer having the laminated structure.

12. A coil, comprising one or more of the insulated wire produced by the method according to claim 10 .

13. A rotating electrical machine, comprising the coil according to claim 12 .

14. An electrical or electronic equipment, having the coil according to claim 12 .