WO2018186259A1

WO2018186259A1 - Insulated electric wire

Info

Publication number: WO2018186259A1
Application number: PCT/JP2018/012828
Authority: WO
Inventors: 齋藤　秀明; 雅晃山内; 槙弥太田; 修平前田; 吉田　健吾; 田村　康
Original assignee: 住友電気工業株式会社; 住友電工ウインテック株式会社
Priority date: 2017-04-03
Filing date: 2018-03-28
Publication date: 2018-10-11
Also published as: CN110462755A; JPWO2018186259A1

Abstract

Provided is an insulated electric wire comprising a linear conductor and an insulation layer that covers an outer peripheral surface of the conductor. The insulation layer includes a polyimide layer and a polyamide-imide layer having a plurality of holes inside thereof. The porosity of the polyamide-imide layer is 20-80 vol.%.

Description

Insulated wire

The present invention relates to an insulated wire.
This application claims priority based on Japanese Patent Application No. 2017-073755 filed on Apr. 3, 2017, and incorporates all the description content described in the above Japanese application.

Coils with insulated wires wound around are used as components that make up general household electrical equipment and automotive electrical equipment. The insulated electric wire which comprises such a coil is equipped with the metal conductor part which has electroconductivity, and the resin insulation layer which coat | covers this.

In an electric device used at a high voltage, when a high voltage is applied to an insulated wire constituting the electric device, partial discharge (corona discharge) is likely to occur on the surface of the insulating layer. When corona discharge occurs, dielectric breakdown tends to occur. Therefore, in addition to having excellent insulation properties and high mechanical characteristics, insulated wires for electrical equipment used at high voltages are required to suppress the occurrence of corona discharge. In order to suppress the occurrence of corona discharge, it is effective to use an insulated wire provided with an insulating layer having a low dielectric constant. As an insulated wire provided with an insulating layer having a low dielectric constant, an insulated wire including an insulating layer in which holes are formed has been proposed (see, for example, Patent Document 1).

JP 2012-224714 A

The insulated wire of the present disclosure includes a linear conductor portion and an insulating layer that covers the outer peripheral surface of the conductor portion. The insulating layer includes a polyamideimide layer having a plurality of pores therein and a polyimide layer. The porosity of the polyamideimide layer is 20% by volume or more and 80% by volume or less.

FIG. 3 is a schematic cross-sectional view showing the structure of the insulated wire in the first embodiment. FIG. 10 is a schematic cross-sectional view showing a first modification of the first embodiment. 6 is a schematic cross-sectional view showing the structure of an insulated wire in Embodiment 2. FIG. 6 is a schematic cross-sectional view showing a first modification of the second embodiment. FIG. 10 is a schematic cross-sectional view showing a second modification of the second embodiment. FIG. FIG. 10 is a schematic cross-sectional view showing a third modification of the second embodiment. 6 is a schematic cross-sectional view showing the structure of an insulated wire in Embodiment 3. FIG. FIG. 10 is a schematic cross-sectional view showing a first modification of the third embodiment. FIG. 9 is a schematic cross-sectional view showing the structure of an insulated wire in a fourth embodiment. FIG. 10 is a schematic cross-sectional view showing a first modification of the fourth embodiment. FIG. 10 is a schematic cross-sectional view showing the structure of an insulated wire in a fifth embodiment. FIG. 10 is a schematic cross-sectional view showing a first modification of the fifth embodiment.

[Problems to be solved by the present disclosure]
Polyimide may be used as a material constituting the insulating layer in a conventional insulated wire. This is because polyimide is excellent in heat resistance and workability. However, since polyimide is expensive, if polyimide is used as a material constituting the insulating layer, the manufacturing cost increases.

Therefore, an object of the present invention is to provide an insulated wire having an insulating layer having excellent heat resistance and work resistance, low cost, and low dielectric constant.

[Effects of the present disclosure]
According to the insulated wire of the present disclosure, it is possible to provide an insulated wire including an insulating layer having excellent heat resistance and workability, low cost, and low dielectric constant.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. The insulated wire of this indication is provided with a linear conductor part and an insulating layer which coat | covers the outer peripheral surface of a conductor part. The insulating layer includes a polyamideimide layer having a plurality of pores therein and a polyimide layer. The porosity of the polyamideimide layer is 20% by volume or more and 80% by volume or less.

In the insulated wire of the present disclosure, the insulating layer includes a polyimide layer. By doing in this way, the heat resistance and workability of an insulating layer can be improved. The insulating layer includes a polyamideimide layer. By doing in this way, the manufacturing cost of an insulated wire can be made low compared with the case where an insulating layer is comprised only from a polyimide layer. When the polyamideimide layer has a plurality of pores therein and the porosity of the polyamideimide layer is 20% by volume or more, the dielectric constant of the polyamideimide layer can be lowered. By including the polyamideimide layer having a low dielectric constant in this way, the dielectric constant of the entire insulating layer can be lowered. On the other hand, by setting the porosity of the polyamideimide layer to 80% by volume or less, the dielectric constant can be lowered while suppressing a decrease in insulation. As a result, according to the insulated wire of the present disclosure, it is possible to provide an insulated wire including an insulating layer having excellent heat resistance and workability, low cost, and low dielectric constant. Here, the porosity of the polyamideimide layer means the ratio of the total volume of the pores to the total volume including the pores of the polyamideimide layer.

In the above insulated wire, the polyimide layer may be a solid layer. By doing in this way, the heat resistance and workability of an insulating layer can be improved more reliably.

In the insulated wire, the polyimide layer may be disposed so as to include the outer peripheral surface of the insulating layer. By doing in this way, when an insulated wire is used in oil, it can control that oil penetrates into an insulating layer and durability falls.

In the insulated wire, the average diameter of the pores formed in the polyamideimide layer is preferably 1 μm or more and 10 μm or less. By setting the average diameter of the pores formed in the polyamideimide layer to 1 μm or more, the dielectric constant of the polyamideimide layer can be lowered, and the dielectric constant of the entire insulating layer can be lowered more reliably. On the other hand, if the average diameter of the pores formed in the polyamideimide layer exceeds 10 μm, the dielectric constant is lowered, but the insulating property is lowered.

In the insulated wire, the ratio of the thickness of the polyamideimide layer to the thickness of the insulating layer is preferably 20% or more and 90% or less. By making the ratio of the thickness of the polyamideimide layer to the thickness of the insulating layer 20% or more, the manufacturing cost of the insulated wire can be reduced more reliably. On the other hand, when the ratio of the thickness of the polyamideimide layer to the thickness of the insulating layer exceeds 90%, the heat resistance and workability of the insulating layer are lowered.

In the insulated wire, a primer layer may be provided between the conductor portion and the insulating layer. By doing so, it is possible to improve the adhesion between the conductor and the insulating layer, and as a result, the properties of the insulated wire such as flexibility, wear resistance, scratch resistance, and workability can be improved. Can be effectively increased.

In the above insulated wire, the plurality of holes may be provided with an outer shell at the peripheral edge thereof. By doing so, it is difficult for the holes to communicate with each other, and therefore, the size of the holes in the insulating layer is unlikely to vary. As a result, it is possible to suppress a decrease in strength, insulation and solvent resistance of the insulating layer while reducing the dielectric constant of the insulated wire.

[Details of the embodiment of the present invention]
Next, an embodiment of the insulated wire of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
The insulated wire 1 in Embodiment 1 is shown in FIG. FIG. 1 is a schematic cross-sectional view showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. With reference to FIG. 1, the insulated wire 1 has a circular cross-sectional shape. The insulated wire 1 includes a linear conductor portion 10 having a circular cross-sectional shape and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10.

(Conductor part)
In the present embodiment, the conductor portion 10 has a circular shape in a cross section perpendicular to the longitudinal direction. As the conductor portion 10, a rectangular wire having a rectangular shape, a square wire having a rectangular shape, or the like can be used in addition to a circular wire having a circular cross section perpendicular to the longitudinal direction as in the present embodiment. . Moreover, the strand wire which twisted together the some strand may be sufficient.

The material of the conductor 10 is preferably a metal having high electrical conductivity and high mechanical strength. In the present embodiment, the conductor portion 10 is made of copper. For the conductor portion 10, copper alloy, aluminum, aluminum alloy, nickel, silver, iron, steel, stainless steel, or the like can be used in addition to the copper of the present embodiment. The conductor portion 10 may be formed of the above metal in a linear shape or a multilayer structure in which another metal is coated on the above metal formed in a linear shape. Examples of the multi-layered conductor 10 include a nickel-coated copper wire, a silver-coated copper wire, a copper-coated aluminum wire, and a copper-coated steel wire.

(Insulating layer)
With reference to FIG. 1, insulating layer 20 constituting insulated wire 1 includes a polyimide layer 30 and a polyamideimide layer 40. The insulating layer 20 constituting the insulated wire 1 includes only the polyimide layer 30 and the polyamideimide layer 40 as in the present embodiment, and has a structure in which a plurality of insulating layers are laminated. And at least the polyamideimide layer 40 may be included. Further, the polyamideimide layer 40 and the polyimide layer 30 may be repeatedly included. The polyamideimide layer 40 is disposed so as to cover the outer peripheral surface of the conductor portion 10. The polyamideimide layer 40 has a plurality of holes 15 inside. The thickness of the insulating layer 20 is, for example, 5 μm or more and 200 μm or less. By setting it as such a range, the conductor part 10 can fully be insulated.

The polyamideimide layer 40 is a layer mainly composed of polyamideimide. Here, the main component refers to a component occupying at least 50% by mass or more of the components constituting the polyamideimide layer 40. In the present embodiment, the polyamideimide layer 40 includes polyamideimide, and the remainder is made of inevitable impurities. Synthetic resins constituting the polyamideimide layer 40 are polyamideimide, polyesterimide, polyetherimide, polyamide, polyurethane, polyester, polybenzimidazole, melamine resin, polyvinyl formal, epoxy resin, phenol resin, urea resin, acrylic resin. Or other thermosetting resin. Also, polyamide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polybutylene naphthalate, polyethylene naphthalate, polysulfone, polyethersulfone, polyphenylsulfone, polyetherimide, polyphenylene sulfide, polyetherketone, polyaryletherketone, Thermoplastic resins such as tetrafluoroethylene / ethylene copolymer, polyether ether ketone, and polytetrafluoroethylene may also be included.

In the present embodiment, the lower limit of the ratio of the thickness of the polyamideimide layer 40 to the thickness of the insulating layer 20 is 20%. The upper limit of the ratio of the thickness of the polyamideimide layer 40 to the thickness of the insulating layer 20 is 90%. By making the ratio of the thickness of the polyamideimide layer 40 with respect to the thickness of the insulating layer 20 20% or more, the manufacturing cost of the insulated wire 1 can be reduced more reliably. On the other hand, when the ratio of the thickness of the polyamideimide layer 40 to the thickness of the insulating layer 20 exceeds 90%, the heat resistance and workability of the insulating layer 20 are lowered. When a plurality of polyamideimide layers 40 are included, the ratio of the total thickness of the polyamideimide layers 40 in the insulating layer 20 is 20% or more and 90% or less.

In the present embodiment, the polyamideimide layer 40 has a plurality of pores 15 dispersed therein. The relative dielectric constant is different between the polyamideimide constituting the polyamideimide layer 40 and air. For this reason, the dielectric constant as the whole polyamideimide layer 40 changes by forming the several void | hole 15 in the polyamideimide layer 40. FIG. As a result, the dielectric constant of the entire insulating layer 20 including the polyamideimide layer 40 changes. For example, the relative permittivity of polyamideimide is higher than that of air (relative permittivity: about 1.0). For this reason, when the polyamideimide layer 40 is made of polyamideimide, the pores 15 are formed in the polyamideimide layer 40, so that the dielectric constant can be made lower than that of the polyamideimide layer 40 in which the holes 15 are not formed. .

The upper limit of the ratio (porosity) of the total volume of the pores 15 to the total volume (including the pores 15) of the polyamideimide layer 40 in the present embodiment is 80% by volume. The lower limit of the porosity of the polyamideimide layer 40 is 20% by volume. By setting the porosity of the polyamideimide layer 40 to 20% by volume or more, the dielectric constant of the polyamideimide layer 40 can be lowered and the dielectric constant of the entire insulating layer 20 can be lowered more reliably. On the other hand, if the porosity of the polyamideimide layer 40 exceeds 80% by volume, the dielectric constant is lowered, but the insulating properties are lowered. A preferable range of the upper limit of the porosity of the polyamideimide layer 40 is 60% by volume or less from the viewpoint of ensuring insulation. A preferable lower limit of the porosity of the polyamideimide layer 40 is 25% by volume or more from the viewpoint of more reliably lowering the dielectric constant of the entire insulating layer 20. In the case where the insulating layer includes a plurality of polyamideimide layers 40, the ratio of the total volume of pores to the total volume of the polyamideimide layers in the insulating layer 20 may be within the above range. The porosity of the polyamideimide layer 40 is such that the polyamideimide layer 40 is peeled off from the conductor 10 and the polyamideimide layer 40 has an apparent volume V1 calculated from the actual mass W2 of the peeled polyamideimide layer and its outer shape. From the mass W1 when there is no hole obtained by multiplying by the density of (W1-W2) × 100 / W1, it can be obtained by the equation.

The lower limit of the average diameter of the pores 15 formed in the polyamideimide layer 40 in the present embodiment is 1 μm. The upper limit of the average diameter of the pores 15 formed in the polyamideimide layer 40 is 10 μm. By setting the average diameter of the holes 15 formed in the polyamideimide layer 40 to 1 μm or more, the dielectric constant of the polyamideimide layer 40 can be lowered, and the dielectric constant of the entire insulating layer 20 can be lowered more reliably. On the other hand, when the average diameter of the pores 15 formed in the polyamideimide layer 40 exceeds 10 μm, the dielectric constant is lowered, but the insulating property is lowered. The average diameter of the pores 15 is a value obtained by measuring a cross section with a pore diameter distribution measuring device (for example, “Porous Material Automatic Pore Diameter Distribution Measuring System” manufactured by Porous Materials).

The polyimide layer 30 is a layer mainly composed of polyimide. Here, the main component refers to a component that occupies at least 50 mass% or more of the components constituting the polyimide layer 30. In the present embodiment, the polyimide layer 30 includes polyimide, and the remainder is made of inevitable impurities. Synthetic resins constituting the polyimide layer 30 include, in addition to polyimide, polyesterimide, polyetherimide, polyamide, polyurethane, polyester, polybenzimidazole, melamine resin, polyvinyl formal, epoxy resin, phenol resin, urea resin, acrylic resin, and the like. A thermosetting resin may be included. Also, polyamide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polybutylene naphthalate, polyethylene naphthalate, polysulfone, polyethersulfone, polyphenylsulfone, polyetherimide, polyphenylene sulfide, polyetherketone, polyaryletherketone, Thermoplastic resins such as tetrafluoroethylene / ethylene copolymer, polyether ether ketone, and polytetrafluoroethylene may also be included.

The polyimide constituting the polyimide layer 30 is formed, for example, by synthesizing a polyimide precursor obtained by condensation polymerization of aromatic diamine and aromatic tetracarboxylic dianhydride and imidizing by heating or the like. As the aromatic tetracarboxylic dianhydride, pyromellitic dianhydride (PMDA) or the like can be used. As the aromatic diamine, 4,4′-diaminodiphenyl ether (ODA) or the like can be used.

Referring to FIG. 1, polyimide layer 30 in the present embodiment is a solid layer. Here, the solid layer refers to a layer in which the holes 15 are not intentionally formed, that is, a layer in which the holes 15 are not substantially present. Specifically, the porosity of the polyimide layer 30 is, for example, 1% by volume or less. By doing in this way, the heat resistance and workability of the insulating layer 20 can be improved more reliably. The polyimide layer 30 is disposed so as to include the outer peripheral surface of the insulating layer 20. By doing in this way, when the insulated wire 1 is used in oil, it can suppress that oil osmose | permeates the insulating layer 20 and durability falls.

The polyimide layer 30 may have a plurality of holes 15 in addition to the solid layer in which the holes 15 are not formed as in the present embodiment. The 1st modification of the insulated wire 1 in Embodiment 1 is shown in FIG. FIG. 2 is a schematic cross-sectional view showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. Referring to FIG. 2, polyimide layer 30 is disposed so as to include the outer peripheral surface of insulating layer 20, and has a plurality of holes 15 dispersed therein. By doing in this way, the dielectric constant of the whole insulating layer 20 can be made lower.

Here, in the insulated wire 1 of the present embodiment, the insulating layer 20 includes a polyimide layer 30. Thereby, the heat resistance and workability of the insulating layer 20 are improved. The insulating layer 20 includes a polyamideimide layer 40. Thereby, compared with the case where the insulating layer 20 is comprised only from the polyimide layer 30, the manufacturing cost of the insulated wire 1 becomes low. The dielectric constant of the polyamide-imide layer 40 becomes low by having a plurality of pores 15 inside the polyamide-imide layer 40 and setting the porosity of the polyamide-imide layer 40 to 20% by volume or more. By including the polyamideimide layer 40 having a low dielectric constant in this way, the dielectric constant of the insulating layer 20 as a whole is low. On the other hand, by setting the porosity of the polyamideimide layer 40 to 80% by volume or less, the dielectric constant can be lowered while suppressing a decrease in insulation. As a result, the insulated wire 1 is an insulated wire 1 including an insulating layer 20 having excellent heat resistance and workability, low cost, and low dielectric constant.

(Insulated wire manufacturing method)
Next, the outline | summary of the manufacturing method of the insulated wire 1 is demonstrated. The method of manufacturing the insulated wire 1 includes a step of preparing the conductor portion 10, a step of preparing a polyamideimide resin varnish to be the polyamideimide layer 40, a step of preparing a polyimide resin varnish to be the polyimide layer 30, and a conductor. Applying a polyamideimide resin varnish on the outer peripheral surface of the portion 10 and heating it to form a polyamideimide layer 40; and applying a polyimide resin varnish to the outer peripheral surface of the conductor portion 10 on which the polyamideimide layer 40 is formed And forming the polyimide layer 30 by heating.

In the step of preparing the conductor portion 10, the conductor portion 10 which is a wire made of a conductor such as copper is prepared. Next, in the step of preparing a polyamideimide resin varnish, a varnish containing a polyamideimide that is a thermosetting resin and a thermally decomposable resin is prepared. By applying and heating the varnish, the thermally decomposable resin is decomposed and vaporized. Then, the polyamideimide is cured. As a result, a polyamideimide layer 40 having a plurality of pores 15 inside is obtained.

As the thermally decomposable resin, for example, resin particles that thermally decompose at a temperature lower than the curing temperature of the polyamideimide that forms the polyamideimide layer 40 can be used. As the thermally decomposable resin, for example, a crosslinked product of a (meth) acrylic polymer can be used.

In addition, instead of using the single heat decomposable resin, a core shell structure having a core mainly composed of a heat decomposable resin and a shell mainly composed of a resin having a higher heat decomposition temperature than the heat decomposable resin. The hollow forming particles may be used. Since the thermally decomposable resin of the core of the hollow forming particles is gasified by thermal decomposition during baking and scatters through the shell, the hollow forming particles leave an outer shell whose inside is hollow after baking. That is, the hollow-forming particles become hollow particles composed only of the outer shell whose inside is hollow after baking, and the pores 15 are formed in the insulating layer 20. Thus, since the peripheral part of each hole 15 formed in the insulating layer 20 is surrounded by the outer shell, the hollow parts in each hollow particle are difficult to communicate with each other, and the insulating layer 20 is larger than the hollow particle. Since the holes 15 are not easily generated, the sizes of the holes 15 are unlikely to vary. Further, the insulating layer 20 having the voids 15 formed by the hollow particles can have a higher dielectric breakdown voltage than the insulating layer having the voids formed by a single thermally decomposable resin, so that the insulating property is excellent. The insulating layer 20 can be formed. Therefore, it is possible to suppress a decrease in strength, insulation, and solvent resistance of the insulating layer 20 while reducing the dielectric constant of the insulated wire 1. Here, the core-shell structure refers to a structure in which the material forming the core of the particle is different from the material of the shell surrounding the core.

In the pores 15 derived from the core-shell structure hollow-forming particles, the pyrolytic resin of the core of the hollow-forming particles contained in the varnish is gasified by pyrolysis at the time of baking, and the gasified pyrolytic resin passes through the shell. Therefore, at least a part of the outer shell of the hole 15 has a defect such as a crack, a crack or a hole. Thus, formation of the void | hole 15 is ensured because an outer shell has a defect | deletion. Further, since the defect is a crack, a crack or a hole, the effect of preventing the communication of the hole 15 by the outer shell can be enhanced.

The shape of the hole 15 is preferably a flat sphere. Further, if the short axis of the hole 15 is oriented in the direction perpendicular to the conductor surface, the holes 15 formed in the vertical direction where external force is likely to act are difficult to come into contact with each other. Suppressed and formed independent holes 15 (independent holes) are easily maintained. As a result, the insulation and solvent resistance of the insulating layer 20 are less likely to be lowered. Here, the “flattened sphere” means that the maximum diagonal length passing through the center of gravity is the major axis, and the minimum diagonal length passing through the center of gravity is the minor axis (the length of the minor axis). It means a sphere, for example, a sphere having a ratio of the minor axis to the major axis in a cross section including the minor axis and the major axis of 0.95 or less. “Oriented in the direction perpendicular to the conductor surface” means that the angle difference between the minor axis of the hole and the direction perpendicular to the conductor surface is 20 degrees or less.

In the hollow-forming particles having a core-shell structure, the thermally decomposable resin used as the main component of the core is not particularly limited as long as it is a resin particle that thermally decomposes at a temperature lower than the curing temperature of polyamideimide. ) A cross-linked product of an acrylic polymer can be used. The main component of the outer shell is preferably silicone. Since the main component of the outer shell is silicone as described above, elasticity is imparted to the outer shell and insulation and heat resistance are easily improved. As a result, the independent voids surrounded by the outer shell are more easily maintained. . Here, the “main component” is a component having the largest content, for example, a component contained in an amount of 50% by mass or more.

Further, as in the above embodiment, the holes 15 may be formed by foaming using a foaming agent in addition to forming the holes 15 using a thermally decomposable resin. As the foaming agent, for example, a chemical foaming agent or a thermally expandable microcapsule can be used. As a chemical foaming agent, it decomposes | disassembles by heating, for example, generate | occur | produces nitrogen gas, a carbon dioxide gas, carbon monoxide, ammonia gas etc., An organic foaming agent or an inorganic foaming agent etc. can be used. As the thermally expandable microcapsule, for example, a core material made of an internal foaming agent and an outer shell that encloses the core material, and the outer shell expands due to the expansion of the core material can be adopted. Moreover, the varnish containing a high boiling point solvent may be prepared and the hole 15 may be formed. As the high boiling point solvent, a solvent having a boiling point of, for example, 180 ° C. to 300 ° C. can be used. As the high boiling point solvent, for example, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol monomethyl ether, or the like can be used.

Next, in the step of preparing a polyimide resin varnish, a varnish containing polyimide which is a thermosetting resin is prepared. The said varnish is apply | coated to the outer peripheral surface side of the conductor part 10 in which the polyamideimide layer 40 was formed, and the polyimide layer 30 is formed by heating.

Examples of a method for applying the varnish to the outer peripheral surface side of the conductor portion 10 include a method using a coating apparatus including a liquid composition tank storing a liquid varnish and a coating die. According to this coating apparatus, the varnish adheres to the conductor outer peripheral surface side as the conductor portion 10 passes through the liquid composition tank, and then passes through the coating die to apply the varnish to a uniform thickness.

In the step of curing the varnish, the insulating layer 20 is formed by curing the varnish by heating. As an apparatus used for this heating, a cylindrical baking furnace extending along the traveling direction of the conductor portion 10 coated with varnish can be used. As a heating method, hot air heating, infrared heating, high frequency heating, or the like can be employed. Moreover, heating temperature is 300 degreeC or more and 600 degrees C or less, for example.

(Other embodiments)
Next, another embodiment of the insulated wire 1 of the present disclosure will be described. FIG. 3 is a diagram illustrating the insulated wire 1 according to the second embodiment of the present disclosure. FIG. 4 is a diagram illustrating a first modification of the insulated wire 1 according to the second embodiment. FIG. 5 is a diagram illustrating a second modification of the insulated wire 1 according to the second embodiment. FIG. 6 is a diagram illustrating a third modification of the insulated wire 1 according to the second embodiment. 3 to 6 are schematic cross-sectional views showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. FIG. 7 is a diagram illustrating the insulated wire 1 according to the third embodiment of the present disclosure. FIG. 8 is a diagram showing a first modification of the insulated wire 1 in the third embodiment. 7 and 8 are schematic cross-sectional views showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. FIG. 9 is a diagram illustrating the insulated wire 1 according to the fourth embodiment of the present disclosure. FIG. 10 is a diagram illustrating a first modification of the insulated wire 1 according to the fourth embodiment. 9 and 10 are schematic cross-sectional views showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. FIG. 11 is a diagram illustrating the insulated wire 1 according to the fifth embodiment of the present disclosure. FIG. 12 is a diagram illustrating a first modification of the insulated wire 1 according to the fifth embodiment. 11 and 12 are schematic cross-sectional views showing a cross section perpendicular to the longitudinal direction of the insulated wire 1. The insulated wire 1 in the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment basically has the same configuration as that in the first embodiment. However, in the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment, the structure of the insulating layer 20 is different from that in the first embodiment. Hereinafter, differences from the case of the first embodiment will be described.

Referring to FIG. 3, the insulated wire 1 in the second embodiment includes a linear conductor portion 10 having a circular cross-sectional shape and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10. The insulating layer 20 includes a first polyimide layer 301, a polyamideimide layer 40, and a second polyimide layer 302. The first polyimide layer 301 is disposed so as to cover the outer peripheral surface of the conductor portion 10. The polyamideimide layer 40 is laminated on the first polyimide layer 301 disposed so as to cover the outer peripheral surface of the conductor portion 10. The second polyimide layer 302 is laminated on the polyamideimide layer 40 and disposed so as to include the outer peripheral surface of the insulating layer 20. The first polyimide layer 301 and the second polyimide layer 302 are solid layers. By doing in this way, the heat resistance and workability of the insulating layer 20 can be improved more reliably. Referring to FIG. 4, first polyimide layer 301 may have a plurality of holes 15 dispersed therein, and second polyimide layer 302 may be a solid layer. Referring to FIG. 5, the first polyimide layer 301 may be a solid layer, and the second polyimide layer 302 may have a plurality of holes 15 dispersed therein. In addition, referring to FIG. 6, first polyimide layer 301 and second polyimide layer 302 may have a plurality of holes 15 dispersed therein. By doing in this way, the dielectric constant of the whole insulating layer 20 can be made lower. The insulating layer 20 may include a plurality of first polyimide layers 301, polyamideimide layers 40, and second polyimide layers 302.

Referring to FIG. 7, the insulated wire 1 in the third embodiment includes a linear conductor portion 10 having a circular cross-sectional shape and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10. The insulating layer 20 includes a polyimide layer 30 and a polyamideimide layer 40. The polyimide layer 30 is disposed so as to cover the outer peripheral surface of the conductor portion 10. The polyamideimide layer 40 is laminated on the polyimide layer 30 disposed so as to cover the outer peripheral surface of the conductor portion 10, and is disposed so as to include the outer peripheral surface of the insulating layer 20. The polyimide layer 30 is a solid layer. Referring to FIG. 8, polyimide layer 30 may have a plurality of holes 15 dispersed therein. The insulating layer 20 may include a plurality of polyimide layers 30 and polyamideimide layers 40 repeatedly.

Referring to FIG. 9, the insulated wire 1 in the fourth embodiment includes a linear conductor portion 10 having a circular cross-sectional shape and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10. The insulating layer 20 includes a first polyimide layer 301, a second polyimide layer 302, and a polyamideimide layer 40. The first polyimide layer 301 is disposed so as to cover the outer peripheral surface of the conductor portion 10. The second polyimide layer 302 is laminated on the first polyimide layer 301. The polyamideimide layer 40 is laminated on the second polyimide layer 302 and disposed so as to include the outer peripheral surface of the insulating layer 20. The first polyimide layer 301 is a solid layer, and the second polyimide layer 302 has a plurality of holes 15 dispersed therein. Referring to FIG. 10, the first polyimide layer 301 may have a plurality of holes 15 dispersed therein, and the second polyimide layer 302 may be a solid layer. Note that the insulating layer 20 may include a plurality of first polyimide layers 301, second polyimide layers 302, and polyamideimide layers 40.

Referring to FIG. 11, the insulated wire 1 in the fifth embodiment includes a linear conductor portion 10 having a circular cross-sectional shape and an insulating layer 20 that covers the outer peripheral surface of the conductor portion 10. The insulating layer 20 includes a polyamideimide layer 40, a first polyimide layer 301, and a second polyimide layer 302. The polyamideimide layer 40 is disposed so as to cover the outer peripheral surface of the conductor portion 10. The first polyimide layer 301 is laminated on the polyamideimide layer 40. The second polyimide layer 302 is laminated on the first polyimide layer 301 and is disposed so as to include the outer peripheral surface of the insulating layer 20. The first polyimide layer 301 is a solid layer, and the second polyimide layer 302 has a plurality of holes 15 dispersed therein. Referring to FIG. 12, the first polyimide layer 301 may have a plurality of holes 15 dispersed therein, and the second polyimide layer 302 may be a solid layer. Insulating layer 20 may include a plurality of polyamideimide layers 40, first polyimide layers 301, and second polyimide layers 302.

The insulated wire 1 having the structure of the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment also has excellent heat resistance and work resistance as in the first embodiment, and is low. The insulated wire 1 provided with the insulating layer 20 having a low dielectric constant at low cost can be provided.

It should be understood that the embodiment disclosed herein is illustrative in all respects and is not restrictive in any way. The scope of the present invention is defined not by the above-described meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

For example, in the insulated wire 1 of the above embodiment, a further layer such as a primer layer may be provided between the conductor portion 10 and the insulating layer 20. A primer layer is a layer provided in order to improve the adhesiveness between layers, for example, can be formed with a well-known resin composition.

When providing a primer layer between the conductor part 10 and the insulating layer 20, the resin composition which forms this primer layer is, for example, one or more kinds of resins among polyimide, polyamideimide, polyesterimide, polyester and phenoxy resin. It is good to include. Moreover, the resin composition forming the primer layer may contain an additive such as an adhesion improver. By forming a primer layer between the conductor portion 10 and the insulating layer 20 with such a resin composition, it is possible to improve the adhesion between the conductor and the insulating layer. 1 characteristics such as flexibility, wear resistance, scratch resistance, and workability can be effectively enhanced.

Further, the resin composition forming the primer layer may contain other resins, for example, an epoxy resin, a phenoxy resin, a melamine resin, etc. together with the above resin. Moreover, you may use a commercially available liquid composition (insulation varnish) as each resin contained in the resin composition which forms a primer layer.

The lower limit of the average primer layer thickness is preferably 1 μm, more preferably 2 μm. On the other hand, the upper limit of the average thickness of the primer layer is preferably 30 μm, more preferably 20 μm. There exists a possibility that sufficient adhesiveness with the conductor part 10 cannot be exhibited as the average thickness of a primer layer is less than the said minimum. Conversely, if the average thickness of the primer layer exceeds the above upper limit, the insulated wire 1 may unnecessarily increase in diameter.

DESCRIPTION OF SYMBOLS 1 Insulated wire, 10 Conductor part, 15 Hole, 20 Insulating layer 30 Polyimide layer, 301 1st polyimide layer, 302 2nd polyimide layer 40 Polyamideimide layer

Claims

A linear conductor,
An insulating layer covering the outer peripheral surface of the conductor portion;
With
The insulating layer is
A polyamideimide layer having a plurality of pores therein;
A polyimide layer,
The porosity of the said polyamideimide layer is an insulated wire which is 20 volume% or more and 80 volume% or less.
The insulated wire according to claim 1, wherein the polyimide layer is a solid layer.
The insulated wire according to claim 2, wherein the polyimide layer is disposed so as to include an outer peripheral surface of the insulating layer.
The insulated wire according to any one of claims 1 to 3, wherein an average diameter of the pores formed in the polyamide-imide layer is not less than 1 µm and not more than 10 µm.
The insulated wire according to any one of claims 1 to 4, wherein a ratio of the thickness of the polyamideimide layer to the thickness of the insulating layer is 20% or more and 90% or less.
The insulated wire according to any one of claims 1 to 5, further comprising a primer layer between the conductor portion and the insulating layer.
The insulated wire according to any one of claims 1 to 6, wherein each of the plurality of holes includes an outer shell at a peripheral portion thereof.