JP2016015295A - Heat-resistant insulation wire, and electrodeposition liquid used for formation of insulating layer of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant insulation wire having remarkably excellent heat resistance in a surface layer part of an insulating layer; and an electrodeposition liquid for forming the insulating layer.SOLUTION: An insulation wire has a heat-resistant insulating layer. Heat-resistant particles are contained in the insulating layer. The heat-resistant particles are densely arranged in a surface layer part of the insulating layer: For example, the amount of the heat-resistant particles contained in the part up to 0.5 μm from the surface of the insulating layer is two times or more of the amount of the heat-resistant particles contained in the central part of the insulating layer. An electrodeposition liquid for formation of the insulating layer is obtained by dispersing heat-resistant particles in a suspension having resin particles dispersed therein, and has a viscosity of 100 cP or less and a turbidity of 1 mg/L or more.

Description

The present invention relates to an insulated wire having a heat-resistant insulating layer and an electrodeposition liquid for forming the insulating layer.

Insulated wires are widely used for magnet coils and the like. An immersion method and an electrodeposition method are known as methods for forming an insulating layer of an insulated wire. The dipping method is a method of forming an insulating coating on the surface of a wire by dipping a conductive wire used as a core material of an insulated wire in a paint such as a resin varnish, lifting it, and drying it. In the electrodeposition method, the wire is placed in an electrodeposition liquid containing a paint component such as a resin varnish, the electrode is energized with the wire as an anode or a cathode, and the paint component is electrodeposited on the surface of the wire, followed by baking treatment to form an insulating layer. (Refer to Patent Document 1 and Patent Document 2).
The dipping method has a drawback in that the paint hardly adheres to the corners of the flat electric wire, and the layer thickness of the corners becomes thinner than the layer thickness of the flat part. On the other hand, the electrodeposition method has an advantage that an insulating layer equal to or more than the flat portion can be formed at the corner portion because the coating is sufficiently electrodeposited at the corner portion of the flat electric wire.

In recent years, there has been a demand for insulated wires having excellent withstand voltage strength and heat resistance in order to support a wide range of applications, and as a means to increase the heat resistance of the insulating layer, metal oxide fine particles and silica fine particles are contained in the resin of the insulating layer. A coating material for enameled wire containing bismuth is known (Patent Document 3).

However, the paint described in Patent Document 3 is for the dipping method, and cannot be used for the electrodeposition method with the liquid composition or liquid state of the disclosed paint. In the dipping method, it is necessary to repeat dipping and drying many times in order to reach a desired layer thickness. For example, dipping is repeated seven times in order to form a coating having a layer thickness of 35 μm that is practically used. For this reason, productivity is low. Further, the dipping method cannot solve the disadvantage that the layer thickness of the corner portion becomes thinner than that of the flat portion in the flat wire. In addition, since an organic solvent is used as a solvent / dispersion medium for resin and oxide fine particles, the environmental load is large.

Further, in the immersion method, when silica fine particles are contained in the insulating layer, since the immersion is repeated in the paint containing the silica fine particles, the silica fine particles are included in each layer, and the silica fine particles are dispersed throughout the insulating layer. . However, since the surface of the insulating layer is most exposed to heat at a high temperature, the surface of the insulating layer is likely to be damaged if there are few silica particles near the surface of the insulating layer.

JP 62-037396 A Japanese Patent Laid-Open No. 03-241609 JP 2001-307557 A

The present invention solves the above-mentioned problems in the conventional insulated wire by the dipping method and the method for producing the same, and has a heat-resistant insulated wire with excellent heat resistance in the vicinity of the surface of the insulating layer and electrodeposition for forming the insulating layer. Provide liquid.

The present invention relates to a heat-resistant insulated wire having the following configuration and an electrodeposition solution thereof.
[1] An insulated wire having a heat-resistant insulating layer, wherein the insulating layer contains heat-resistant particles, and the heat-resistant particles are densely packed in the surface layer thickness portion of the insulating layer. Heat resistant insulated wire.
[2] The heat-resistant insulated wire according to [1], wherein heat-resistant particles are concentrated in a layer thickness portion of 0.5 μm from the surface of the insulating layer.
[3] The above [1], wherein the amount of heat-resistant particles contained in a layer thickness portion of 0.5 μm from the surface of the insulating layer is at least twice the amount of heat-resistant particles contained in the central portion of the insulating layer. Or the heat resistant insulated wire as described in said [2].
[4] An electrodeposition liquid used for forming the insulating layer according to claim 1, wherein heat-resistant particles are dispersed in a suspension in which resin particles are dispersed, and has a viscosity of 100 cP or less and a turbidity of 1 mg. An electrodeposition liquid for forming an insulating layer, characterized by being not less than / L.
[5] The insulation according to [4], wherein the content of the resin particles is 1 to 30% by mass, and the heat-resistant particles are contained in an amount of 1 to 100 parts by mass with respect to 100 parts by mass of the resin particles. Electrodeposition liquid for layer formation.
[6] The insulating layer forming electrodeposition liquid as described in [4] or [5] above, wherein the resin particles have an average particle diameter of 1 μm or less and the heat-resistant particles have an average particle diameter of 500 nm or less.
[7] The electrodeposition liquid for forming an insulating layer according to any one of [4] to [6] above, wherein an insulating layer having a softening temperature increase rate of 1.2 or more is formed.
[8] The electrodeposition liquid for forming an insulating layer according to any one of [5] to [7] above, wherein the resin particles are an acrylic resin, a polyesterimide resin, a polyimide resin, or a polyamideimide resin.
[9] The electrodeposition liquid for forming an insulating layer according to any one of [5] to [8] above, wherein the heat-resistant particles are at least one of metal oxide fine particles and silica fine particles.

[Specific description]
The heat-resistant insulated wire of the present invention is an insulated wire having a heat-resistant insulating layer, containing heat-resistant particles in the insulating layer, and the heat-resistant particles are densely packed in the surface layer thickness portion of the insulating layer. It is an insulated wire characterized by this.

In the heat-resistant insulated wire of the present invention, the surface layer thickness portion of the insulating layer is a distance from the surface of the insulating layer on a perpendicular line connecting the surface of the conductive wire of the insulated wire and the surface of the insulating layer. The layer thickness is up to 5 μm. In general, the thickness of the entire insulating layer is approximately 2 to 50 μm, and usually 3 to 30 μm.

In the heat-resistant insulated wire of the present invention, preferably, the amount of the heat-resistant particles contained in the layer thickness portion of 0.5 μm from the surface of the insulating layer is the amount of the heat-resistant particles contained in the central portion of the insulating layer. 2 times or more. The central portion of the insulating layer is a vertical line connecting the surface of the conductive wire and the surface of the insulating layer, from the position of 1/3 · L from the surface of the insulating layer with respect to the layer thickness L of the entire insulating layer. It is a range up to a position of 2/3 · L.

An example of the heat-resistant insulated wire of the present invention is shown in FIG. FIG. 1 is a partial sectional view of a heat-resistant insulated wire according to the present invention. The conductive wire 10, in the illustrated example, includes a heat-resistant particle in an insulating layer 20 made of a heat-resistant resin that covers the copper wire 10. In the figure, the white spots inside the insulating layer 20 are the heat-resistant particles 30. The heat-resistant particles 30 in the illustrated example are silica fine particles. As shown in the figure, white spots are concentrated in the 0.5 μm thick portion from the surface of the insulating layer 20, and it can be seen that the heat-resistant particles 30 are unevenly distributed in this portion.

FIG. 2 and FIG. 3 show the results of elemental analysis by energy dispersive X-ray spectroscopic analysis (hereinafter referred to as EDS analysis) for the elements contained in the cross-sectional portion shown in FIG. FIG. 2 is a chart of an EDS analysis result at a position where the distance from the surface of the insulating layer is 0.25 μm on the vertical line connecting the surface of the copper wire 10 and the surface of the insulating layer 20. FIG. 3 is a chart of the EDS analysis result when the distance from the surface of the insulating layer is a half of the thickness of the entire insulating layer on the vertical line connecting the surface of the copper wire 10 and the surface of the insulating layer 20. .

The ratio (Si / C) of the intensity peak of silicon (Si in the figure) to the intensity peak of carbon (C in the figure) is an average of 5 analyzes, and in FIG. 2, Si / C = 20/80, In FIG. 3, Si / C = 5/95, and the amount of silica fine particles contained in the surface layer thickness portion of the insulating layer shown in FIG. 2 is about the amount of silica fine particles contained in the central portion of the insulating layer shown in FIG. 4 times.

In the heat-resistant insulated wire of the present invention, the heat-resistant particles contained in the insulating layer are densely packed in the surface layer thickness portion of the insulating layer. For example, in the illustrated example, the silica contained in the surface layer thickness portion of the insulating layer Since the amount of fine particles is about four times the amount of silica fine particles contained in the central portion of the insulating layer, the heat resistance of the surface layer thickness portion that is most exposed to heat at high temperatures is high. For this reason, even if there is little quantity of the heat resistant particle contained in the whole insulating layer, the outstanding heat resistance can be obtained.

In the heat resistant insulated wire of the present invention, the insulating layer is formed of an acrylic resin, a polyesterimide resin, or a polyimide resin, and the heat resistant particles contained in the insulating layer are metal oxide fine particles or silica fine particles. is there. Examples of the metal oxide include alumina and zirconia.

The said insulating layer of the heat resistant insulated wire which concerns on this invention can be formed with the electrodeposition liquid of this invention. The electrodeposition liquid of the present invention is a suspension in which resin particles and heat-resistant particles are dispersed. The electrodeposition liquid of the present invention can be obtained by mixing a suspension in which heat-resistant particles are dispersed in a suspension in which resin particles are dispersed. The dispersion medium of the resin particle suspension may be a liquid used in the electrodeposition method, and is a water-aprotic polar solvent such as water, water-N, N dimethylformamide, water-N methylpyrrolidone, water-dimethyl sulfoxide. A mixed solution or the like is used. A dispersion medium having a good compatibility with the resin particle suspension is used for the dispersion of the heat-resistant particle suspension.

The electrodeposition liquid of the present invention is a suspension having a turbidity of 1 mg / L or more, preferably 10 to 600 mg / L, in which resin particles and heat-resistant particles are dispersed. If the turbidity of the electrodeposition liquid is less than 1 mg / L, the dispersion state of the resin particles and heat-resistant particles in the liquid is insufficient, and the amount of resin particles and heat-resistant particles is insufficient. It is difficult to form an insulating layer. Since the electrodeposition liquid of the present invention has a turbidity of 1 mg / L or more, the dispersion state of the resin particles and heat-resistant particles in the liquid is good, and since it contains a sufficient amount of resin particles and heat-resistant particles, it has good heat resistance. An insulating layer can be formed.

In the electrodeposition method, the conductive wire immersed in the electrodeposition liquid is energized, and the resin particles and heat-resistant particles in the liquid are electrically moved to the surface of the wire to form an insulating layer. The electrodeposition solution is required to have a low viscosity so that the solution does not solidify. If the viscosity of the electrodeposition liquid is too high, the liquid is solidified and cannot be used for film formation. The viscosity of the electrodeposition liquid of the present invention is 100 cP or less, and a viscosity of 0.5 to 90 cP is preferable. Since the electrodeposition liquid of the present invention has a viscosity of 100 cP or less, a good insulating layer can be formed without the liquid solidifying.

On the other hand, in the dipping method, a paint for forming an insulating layer is used. When this paint is applied to the surface of the conductive wire of the insulated wire, a highly viscous liquid is used so that the paint does not flow down. In general, the viscosity of the coating forming paint used in the dipping method is 1000 cP or more. In addition, since the resin component of the coating composition for dipping is dissolved in the paint and is not a suspension in which resin particles are dispersed in the liquid, the turbidity of the paint is generally less than 0.01 mg / L. It is a light transmissive liquid.

Specifically, in the dipping method, paints using polyurethane resin, polyester resin, formal resin, polyesterimide resin, polyamideimide resin, polyimide resin are used, and the viscosity of these paints is 1000 cP or more and turbidity is 0. It is less than 0.01 mg / L, and the viscosity and turbidity of the liquid are completely different from the electrodeposition liquid for forming an insulating layer of the present invention. The electrodeposition liquid of the present invention has a markedly lower viscosity than the coating material for insulating layer used in the dipping method.

The kind of the resin particle contained in the electrodeposition liquid of the present invention is an acrylic resin, a polyesterimide resin, a polyimide resin, or the like. The average particle size of the resin particles is preferably 1 μm or less, and more preferably 10 to 100 nm. If resin particles having an average particle diameter of 1 μm or less are used, the dispersion stability of the resin particles is improved. As for content of the resin particle contained in the electrodeposition liquid of this invention, 1-30 mass% is preferable. Since the electrodeposition liquid of the present invention contains the resin particles having the above content, an insulating layer having a sufficient thickness can be formed.

In the electrodeposition liquid of the present invention, heat-resistant particles are dispersed together with the resin particles. The heat-resistant particles are metal oxide fine particles or silica fine particles. Examples of the metal oxide include alumina and zirconia. In order to uniformly disperse the heat-resistant particles in the suspension of the resin particles, the heat-resistant particles are dispersed in advance in a dispersion medium having good compatibility with the suspension, and the dispersion is used as a suspension of the resin particles. To be mixed.

The heat resistant particles are preferably colloidal particles of 500 nm or less, more preferably 0.5 to 400 nm. Since the colloidal particles having the above particle diameter are dispersed without being settled in the liquid, a heat resistant coating in which the heat resistant particles are uniformly contained can be formed.

The content of the heat-resistant particles is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the resin particles. When the content is less than 1 part by mass, the heat resistance of the insulating layer becomes insufficient, and when it exceeds 100 parts by mass, the flexibility of the insulating layer is lowered. Since the electrodeposition liquid of the present invention contains the above-mentioned heat-resistant particles, an insulating layer having sufficient heat resistance and flexibility can be formed.

The energization conditions for forming the insulating layer by energizing the conductive wire immersed in the electrodeposition liquid using the electrodeposition liquid of the present invention are the same as in the case of using a general electrodeposition liquid. For example, electrodeposition can be performed at a DC voltage of 5 to 100 V, an electrodeposition time of 0.1 to 30 seconds, and an electrodeposition liquid temperature of 5 to 40 ° C.

Quenching after electrodeposition. The quenching conditions are the same as when using a general electrodeposition solution. For example, it may be put into a baking furnace, heated at 200 to 600 ° C. for 2 to 120 seconds, and then subjected to baking treatment.

By using the electrodeposition liquid of the present invention, an insulating layer in which heat-resistant particles are densely formed on the surface layer thickness portion can be formed.

In the heat-resistant insulated wire of the present invention, since the heat-resistant particles are concentrated on the surface portion of the insulating layer, the heat resistance of the surface portion of the insulating layer that is most exposed to heat at high temperature is high. For this reason, even if there is little quantity of the heat resistant particle contained in the whole insulating layer, the outstanding heat resistance can be obtained.

The electrodeposition liquid of the present invention can form an insulating layer having heat-resistant particles densely on the surface portion. Therefore, it is possible to obtain an insulation coated electric wire having a high softening temperature. Specifically, for example, the rate of increase in the softening temperature represented by the formula of the softening temperature of the insulating layer / the softening temperature of the insulating layer resin is 1.2 or more, preferably 1.3 to 1.5. Insulating coatings can be formed.

In addition, since the electrodeposition liquid of the present invention is used in an electrodeposition method, a desired layer thickness can be obtained by a single electrodeposition process. An insulating coating can be uniformly formed on the corner of the flat electric wire. Furthermore, since water can be used as a dispersion medium for the electrodeposition liquid, the load on the environment is small.

The partial cross section photograph of the insulated wire formed in Example 1. FIG. 2 is an EDS analysis chart at a position where a distance from the surface of the insulating layer is 0.25 μm on a perpendicular line connecting the surface of the copper wire 10 and the surface of the insulating layer 20 in FIG. 1. 2 is an EDS analysis chart in which the distance from the surface of the insulating layer is a half of the thickness of the entire insulating layer on a perpendicular line connecting the surface of the copper wire 10 and the surface of the insulating layer 20 in FIG.

Examples of the present invention are shown below together with comparative examples.
[Examples 1 to 13]
In an aqueous suspension having a resin particle concentration of 20% by mass in which acrylic resin particles having an average particle size of 50 nm are dispersed in water, a silica particle concentration of 30% by mass in which silica particles having an average particle size of 10 nm or an average particle size of 360 nm are dispersed in water and A water-dispersed electrodeposition solution was prepared by mixing 70% by mass of silica sol. Table 1 shows the parts by mass of the silica particles with respect to 100 parts by mass of the resin particles in the electrodeposition liquid. Table 1 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles.
The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 1. The average particle diameters of the acrylic resin particles and the silica particles were measured by a dynamic light scattering particle size distribution analyzer (LB550) manufactured by HORIBA. Moreover, the turbidity of the electrodeposition liquid was measured with an integrating sphere turbidimeter (ANA-148) manufactured by Tokyo Kogyo. The viscosity of the electrodeposition liquid was measured with a capillary viscometer according to JIS (Z8803: 2011-6).
This electrodeposition solution is put into an electrodeposition bath at 25 ° C., a φ0.1 mm copper wire is passed through the electrodeposition bath at a wire speed of 15 m / min, the copper wire is used as an anode, and the electrodeposition bath is used as a cathode. Acrylic resin and silica particles were electrodeposited on the wire surface. After electrodeposition, a mist treatment with DMF was performed, and this was passed through a baking furnace, and a baking treatment was performed at a heating temperature of 300 ° C. for a heating time of 10 seconds to form an insulating layer having a thickness of 10 μm. Table 1 shows the flexibility, softening temperature, softening temperature increase rate, and ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer.
In addition, after the self-winding in accordance with JIS (C3005: 2000-4.20.1), the flexibility is checked with an optical microscope for the presence or absence of peeling of the insulating layer. It was. The softening temperature was measured according to JIS (C3216-6: 2011-4). The rate of increase in softening temperature was determined by the formula of softening temperature / softening temperature of insulating layer resin. The ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer was measured in the same manner as the Si / C ratio measurement method described in paragraph [0013].

[Examples 14 to 23]
Zirconia sol having a zirconia particle concentration of 30% by mass and water of 70% by mass in which zirconia particles having an average particle size of 100 nm are dispersed in water, or an alumina particle concentration of 30% by mass and 70% by mass in which alumina particles having an average particle size of 50 nm are dispersed in water. A water-dispersed electrodeposition solution was prepared in the same manner as in Examples 1 to 13, except that% alumina sol was used. Table 2 shows the parts by mass of the zirconia particles or the alumina particles with respect to 100 parts by mass of the resin particles in the electrodeposition liquid. Table 2 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 2. The average particle diameter of the acrylic resin particles and silica particles, the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13.
Using this electrodeposition solution, an insulating layer having a thickness of 10 μm was formed in the same manner as in Examples 1 to 13. Table 2 shows the flexibility, softening temperature, softening temperature increase rate, and ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer. The flexibility, softening temperature, and softening temperature increase rate were measured in the same manner as in Examples 1 to 13. The ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer is the Si / C ratio measurement method described in paragraph [0013]. Substituting Zr, Examples 19 to 23 were similarly measured by replacing Si with Al.

[Examples 24 to 30]
Polyesterimide resin particles having an average particle diameter of 200 nm are dispersed in water in an aqueous suspension having a resin particle concentration of 20% by mass, silica particles having an average particle diameter of 10 nm in silica dispersed in water are 30% by mass and water is 70% by mass. A water-dispersed electrodeposition solution was prepared by mixing the silica sol. Table 3 shows parts by mass of the silica particles with respect to 100 parts by mass of the resin particles in the electrodeposition liquid. Table 3 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 3. The average particle diameter of the polyesterimide resin particles and silica particles, and the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13.
Using this electrodeposition solution, an insulating layer having a thickness of 10 μm was formed in the same manner as in Examples 1 to 13. Table 3 shows the flexibility, the softening temperature, the softening temperature increase rate, and the ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer. The ratio of the heat resistant particle amount of the insulating layer surface layer thickness portion to the flexibility, softening temperature, softening temperature rise rate, and heat resistant particle amount of the central portion of the insulating layer is the same as in Examples 1 to 13. It was measured.

[Examples 31 to 35]
An aqueous suspension having a resin particle concentration of 20% by mass in which polyimide resin particles having an average particle size of 400 nm are dispersed in water, a silica particle having a concentration of 30% by mass in which silica particles having an average particle size of 10 nm are dispersed in water, and 70% by mass of water. Silica sol was mixed to prepare an aqueous dispersion type electrodeposition solution. Table 3 shows parts by mass of the silica particles with respect to 100 parts by mass of the resin particles in the electrodeposition liquid. Table 3 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 3. The average particle diameter of the polyimide resin particles and silica particles, the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13.
Using this electrodeposition solution, an insulating layer having a thickness of 10 μm was formed in the same manner as in Examples 1 to 13. Table 3 shows the flexibility, the softening temperature, the softening temperature increase rate, and the ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer.
In addition, the ratio of the heat resistant particle amount of the insulating layer surface layer thickness portion to the flexibility, the softening temperature, the softening temperature increase rate, and the heat resistant particle amount of the central portion of the insulating layer is the same as in Examples 1 to 13. And measured.

[Examples 36 to 40]
An aqueous suspension having a resin particle concentration of 20% by mass in which polyamideimide resin particles having an average particle size of 300 nm are dispersed in water, a silica particle concentration of 30% by mass and 70% by mass of water having silica particles having an average particle size of 10 nm dispersed in water. A water-dispersed electrodeposition solution was prepared by mixing the silica sol. Table 4 shows parts by mass of the silica particles with respect to 100 parts by mass of the resin particles in the electrodeposition liquid. Table 4 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 4. The average particle diameter of the polyimide resin particles and silica particles, the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13.
Using this electrodeposition solution, an insulating layer having a thickness of 10 μm was formed in the same manner as in Examples 1 to 13. Table 4 shows the flexibility, softening temperature, softening temperature increase rate, and ratio of the heat-resistant particle amount in the insulating layer surface layer thickness portion to the heat-resistant particle amount in the central portion of the insulating layer.
In addition, the ratio of the heat resistant particle amount of the insulating layer surface layer thickness portion to the flexibility, the softening temperature, the softening temperature increase rate, and the heat resistant particle amount of the central portion of the insulating layer is the same as in Examples 1 to 13. And measured.

In any of the electrodeposition liquids of Examples 1 to 40, the turbidity of the electrodeposition liquid is 30 mg / L or more, the viscosity is 100 cP or less, and the softening temperature of the formed insulating layer is 400 ° C. or more. The softening temperature rise rate is 1.2 or more and has high heat resistance. In any resin type, the softening temperature and the softening temperature increase rate are increased according to the content of the heat-resistant particles. In Example 8, since the content of the silica particles was large, peeling of the insulating layer occurred in the flexibility test. From this result, the amount of the heat-resistant particles is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the resin particles.

[Comparative Examples 1 to 4]
Resin particle concentration 20 in which acrylic resin particles having an average particle size of 50 nm, polyesterimide resin particles having an average particle size of 200 nm, polyimide resin particles having an average particle size of 400 nm, or polyamideimide resin particles having an average particle size of 300 nm are dispersed in water. A mass% aqueous suspension was used as the electrodeposition solution. Table 5 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 5. The average particle diameter of the resin particles, the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13.
Using this electrodeposition solution, an insulating layer having a thickness of 10 μm was formed in the same manner as in Examples 1 to 13. Table 5 shows the flexibility, softening temperature resistance, and softening temperature increase rate of this insulated wire. The flexibility, softening temperature, and softening temperature increase rate were measured in the same manner as in Examples 1 to 13.
In Comparative Examples 1 to 4, the insulating layer was formed by the electrodeposition method, but since it does not contain heat-resistant particles, the softening temperature does not increase and the softening temperature increase rate is 1.

[Comparative Example 5]
A silica sol in which silica particles having an average particle size of 10 nm are dispersed in a mixed solution of xylene and butanol is mixed with the above paint while stirring the paint, and the paint content is 100 parts by mass. The silica particles were dispersed so as to be 20 parts by mass.
Table 5 shows the turbidity, viscosity, liquid state, and resin concentration of the electrodeposition liquid. The xylene and butanol amounts of the electrodeposition solution were adjusted so that the resin particle concentration was the value shown in Table 5. The turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13. Using this electrodeposition solution, an insulating layer was formed in the same manner as in Examples 1 to 13. However, the turbidity of the electrodeposition solution was less than 0.01 mg / L and the viscosity exceeded 1000 cP. No layer was formed.

[Comparative Example 6]
Polyesterimide resin particles having an average particle size of 200 nm are dispersed in water in an aqueous suspension having a resin particle concentration of 40% by mass. Silica particles having an average particle size of 10 nm in silica dispersed in water are 30% by mass and 70% by mass of water. An electrodeposition solution obtained by mixing 1 part by mass of silica particles with 100 parts by mass of the polyesterimide resin was used. Table 5 shows the turbidity, viscosity, liquid state, resin particle concentration, and average particle diameter of the resin particles. The amount of water in the electrodeposition solution was adjusted so that the resin particle concentration was the value shown in Table 5. The average particle diameter of the resin particles, the turbidity and viscosity of the electrodeposition solution were measured in the same manner as in Examples 1 to 13. Using this electrodeposition solution, an attempt was made to form an insulating layer in the same manner as in Examples 1 to 13, but since the resin particle concentration was high and the viscosity of the electrodeposition solution was too high, the solution solidified and could not be electrodeposited. It was.

[Comparative Example 7]
Using a paint in which tris-hydroxyethyl isocyanurate-modified polyesterimide is dissolved, and stirring the paint, a silica sol in which silica particles having an average particle diameter of 10 nm are dispersed in a mixed solution of xylene and butanol is mixed with the paint. The silica particles were dispersed to 20 parts by mass with respect to 100 parts by mass of the resin content. Using this paint, an attempt was made to form an insulating layer by the electrodeposition method in the same manner as in Examples 1 to 13. However, since the resin component was dissolved, the insulating layer could be formed by the electrodeposition method. There wasn't.

10 copper wire 20 insulating layer 30 heat resistant particles

Claims (9)

An insulated wire having a heat-resistant insulating layer, comprising heat-resistant particles in the insulating layer, wherein the heat-resistant particles are concentrated in a surface layer thickness portion of the insulating layer. Electrical wire. The heat-resistant insulated wire according to claim 1, wherein heat-resistant particles are concentrated in a layer thickness portion of 0.5 µm from the surface of the insulating layer. The amount of heat-resistant particles contained in a layer thickness portion of 0.5 μm from the surface of the insulating layer is at least twice the amount of heat-resistant particles contained in the central portion of the insulating layer. Heat-resistant insulated wires described in 1. An electrodeposition solution used for forming the insulating layer according to claim 1, wherein heat-resistant particles are dispersed in a suspension in which resin particles are dispersed, and has a viscosity of 100 cP or less and a turbidity of 1 mg / L or more. An electrodeposition solution for forming an insulating layer, characterized in that 5. The resin for forming an insulating layer according to claim 4, wherein the content of the resin particles is 1 to 30% by mass, and the heat-resistant particles are contained in an amount of 1 to 100 parts by mass with respect to 100 parts by mass of the resin particles. Liquid landing. The electrodeposition liquid for forming an insulating layer according to claim 4 or 5, wherein the resin particles have an average particle diameter of 1 µm or less and the heat-resistant particles have an average particle diameter of 500 nm or less. The electrodeposition liquid for forming an insulating layer according to any one of claims 4 to 6, wherein an insulating layer having a softening temperature increase rate of 1.2 or more is formed. The electrodeposition liquid for forming an insulating layer according to any one of claims 5 to 7, wherein the resin particles are an acrylic resin, a polyesterimide resin, a polyimide resin, or a polyamideimide resin. The electrodeposition liquid for forming an insulating layer according to any one of claims 5 to 8, wherein the heat-resistant particles are at least one of metal oxide fine particles and silica fine particles.