Insulated wire
The insulated wire has a conductor having a long shape, and an insulation film including multiple pores and covering the conductor, wherein an opening area ratio SR measured by a method below is 1% or less. The method of measuring the opening area ratio SR includes peeling the insulation film from the conductor; obtaining a SEM image showing an interface on a conductor side in the insulation film peeled; calculating an area S 1 of an observation region that is at least a part of the SEM image; and an area S 2 of portions where the multiple pores are open in the observation region; and calculating the opening area ratio SR by the following Formula: SR=(S 2 /S 1 )×100.
1 . An insulated wire comprising:
a conductor having a long shape; and
an insulation film including multiple pores and covering the conductor,
wherein an opening area ratio SR measured by a method below is 1% or less:
the method of measuring the opening area ratio SR:
peeling the insulation film from the conductor;
obtaining a SEM image showing an interface on a conductor side in the insulation film peeled;
calculating an area S 1 of an observation region that is at least a part of the SEM image, and an area S 2 of portions where the multiple pores are open in the observation region; and
calculating the opening area ratio SR by Formula (1) below,
SR =( S 2/ S 1)×100 Formula (1).
2 . The insulated wire according to claim 1 ,
wherein the opening area ratio SR is 0.01% or more.
3 . The insulated wire according to claim 1 ,
wherein the insulation film has a porosity of 4% by volume or more.
4 . The insulated wire according to claim 1 ,
wherein the multiple pores are derived from a thermally decomposable polymer in a form of liquid, or a high boiling point solvent.
5 . The insulated wire according to claim 4 ,
wherein the thermally decomposable polymer in the form of liquid is diol-type polypropylene glycol.
6 . The insulated wire according to claim 4 ,
wherein the high boiling point solvent is oleyl alcohol, 1-tetradecanol, or 1-dodecanol.