JP6795555B2 - Manufacturing method of insulated wire, resin composition for forming insulating layer and insulated wire - Google Patents

Description

The present invention relates to an insulated electric wire and a resin composition for forming an insulating layer.

For example, when manufacturing a coil for a motor using an insulated wire, after winding the wire around the core, varnish is impregnated in the gap between the wires and the gap between the wires and the core to fix the wires and the wires to the core. (See Japanese Patent Application Laid-Open No. 2010-238662).

JP-A-2010-238662

However, the resin material used for the impregnated varnish generally has low thermal conductivity and therefore has poor heat dissipation, and as a result, does not contribute to suppressing heat generation of the motor, so that heat tends to be trapped in the motor. In a motor or the like used at a high voltage, the heat generated by the coil is large, so that the insulated wire deteriorates quickly, and the life of the insulated wire and thus the electric device is shortened. For this reason, it is important to efficiently dissipate heat generated by the coil for an insulated wire used in an electric device having a high applicable voltage such as a motor. Therefore, it is important to efficiently dissipate the heat generated by the core and coil.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide an insulated wire having excellent heat dissipation.

The insulated wire according to one aspect of the present invention made to solve the above problems is an insulated wire provided with a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor, and is the above-mentioned insulation. The layer has a matrix containing a synthetic resin as a main component, a heat-dissipating filler dispersed in the matrix, and cellulose nanofibers dispersed in the matrix.

Another resin composition for forming an insulating layer according to another aspect of the present invention is a resin composition for forming an insulating layer used for forming at least one of one or a plurality of insulating layers constituting an insulated electric wire, and is the above-mentioned insulating. It contains a synthetic resin composition that forms a matrix of layers, a heat-dissipating filler dispersed in the synthetic resin composition, and cellulose nanofibers dispersed in the synthetic resin composition.

The insulated wire and the resin composition for forming an insulating layer of the present invention are excellent in heat dissipation.

It is a schematic cross-sectional view which shows the insulated wire which concerns on 1st Embodiment of this invention. It is a schematic cross-sectional view which shows the insulated wire which concerns on 2nd Embodiment of this invention.

[Explanation of Embodiments of the Present Invention]
The insulated wire according to one aspect of the present invention is an insulated wire having a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor, and the insulating layer contains a synthetic resin as a main component. It is an insulated wire having a matrix to be used, a heat-dissipating filler dispersed in the matrix, and cellulose nanofibers dispersed in the matrix.

In the insulated wire, the insulating layer has a matrix containing a synthetic resin as a main component, a heat-dissipating filler dispersed in the matrix, and cellulose nanofibers dispersed in the matrix, so that the heat generated by the heat-dissipating filler is generated. In addition to conduction, cellulose nanofibers increase the thermal conductivity path to the surface side of the insulated wire, resulting in improved thermal conductivity of the insulating layer. Therefore, the insulated wire has excellent heat dissipation. Here, the "cellulose nanofiber" refers to a fine cellulose fiber obtained by defibrating a cellulose-based fiber as a raw material, and generally refers to a cellulose fine fiber having a fiber width of nano size (1 nm or more and 1000 nm or less). Refers to the cellulose fiber contained. The "main component" is a component having the highest content, for example, a component contained in an amount of 50% by mass or more.

The content of the cellulose nanofibers with respect to the synthetic resin is preferably 0.5% by volume or more and 10.0% by volume or less. By setting the content of the cellulose nanofibers within the above range, the heat dissipation of the insulated wire can be further improved by setting the content of the cellulose nanofibers within the above range.

The content of the heat-dissipating filler with respect to the synthetic resin is preferably 5% by volume or more and 60% by volume or less. By setting the content of the heat-dissipating filler with respect to the synthetic resin within the above range, the heat-dissipating property of the insulated wire can be further improved.

The resin composition for forming an insulating layer according to one aspect of the present invention is a resin composition for forming an insulating layer used for forming at least one of one or a plurality of insulating layers constituting an insulated electric wire, and is a resin composition for forming an insulating layer. It contains a synthetic resin composition that forms a matrix, a heat-dissipating filler dispersed in the synthetic resin composition, and cellulose nanofibers dispersed in the synthetic resin composition.

The resin composition for forming an insulating layer contains a heat-dissipating filler and cellulose nanofibers dispersed in the synthetic resin composition forming a matrix of the insulating layer, so that the cellulose nanofibers are added to the thermal conductivity by the heat-dissipating filler. As a result, the thermal conductivity to the surface side of the insulated wire is increased, and as a result, the thermal conductivity of the insulating layer can be increased. Therefore, an insulating layer having excellent heat dissipation can be formed.

[Details of Embodiments of the present invention]
Hereinafter, embodiments of the insulated wire according to the present invention will be described in detail with reference to the drawings.

<First Embodiment>
<Insulated wire>
FIG. 1 is a schematic cross-sectional view showing an insulated wire according to the first embodiment of the present invention. As shown in FIG. 1, the insulated wire 10 includes a linear metal conductor 1 and a one-layer insulating layer 3 laminated on the outer peripheral surface of the metal conductor 1. The insulating layer 3 is formed by using the resin composition for forming the insulating layer.

[Metal conductor]
The metal conductor 1 is, for example, a round wire having a circular cross section, but may be a square wire having a square cross section, a flat wire having a rectangular cross section, or a stranded wire obtained by twisting a plurality of strands.

As the material of the metal conductor 1, a metal having high conductivity and high mechanical strength is preferable. Examples of such metals include copper, copper alloys, aluminum, aluminum alloys, nickel, silver, mild iron, steel, stainless steel and the like. The metal conductor 1 is a material in which these metals are linearly formed, or a material having a multilayer structure in which such a linear material is coated with another metal, for example, nickel-coated copper wire, silver-coated copper wire, or copper-coated material. Aluminum wire, copper-coated steel wire and the like can be used.

As the lower limit of the average cross-sectional area of the metal conductor 1, 0.01 mm ² is preferable, and 0.1 mm ² is more preferable. On the other hand, as the upper limit of the average cross-sectional area of the metal conductor 1, 10 mm ² is preferable, and 5 mm ² is more preferable. If the average cross-sectional area of the metal conductor 1 is less than the above lower limit, the volume of the insulating layer 3 with respect to the metal conductor 1 may increase, and the volumetric efficiency of the coil or the like formed by using the insulated wire may decrease. On the contrary, when the average cross-sectional area of the metal conductor 1 exceeds the above upper limit, the insulating layer 3 must be formed thick in order to sufficiently reduce the dielectric constant, and the diameter of the insulated wire may be unnecessarily increased. There is.

[Insulation layer]
As shown in FIG. 1, the insulating layer 3 has a matrix 2 containing a synthetic resin as a main component, a heat-dissipating filler 4 dispersed in the matrix 2, and cellulose nanofibers 5 dispersed in the matrix 2.

As the lower limit of the average thickness of the insulating layer 3, 5 μm is preferable, and 10 μm is more preferable. On the other hand, the upper limit of the average thickness of the insulating layer 3 is preferably 500 μm, more preferably 450 μm. If the average thickness of the insulating layer 3 is less than the above lower limit, the insulating property may decrease. The presence of the cellulose nanofibers 5 may easily form an uneven shape on the surface of the insulating layer 3. On the contrary, when the average thickness of the insulating layer 3 exceeds the above upper limit, the volumetric efficiency of the coil or the like formed by using the insulated wire may decrease.

The lower limit of the thermal conductivity of the insulating layer 3 in the thickness direction at 25 ° C. is preferably 0.25 W / m · K, more preferably 0.30 W / m · K. If the thermal conductivity of the insulating layer 3 in the thickness direction at 25 ° C. is less than the above lower limit, the effect of preventing deterioration of the insulated wire may not be sufficiently obtained.

(matrix)
The synthetic resin that is the main component of the matrix 2 of the insulating layer 3 is not particularly limited as long as it is a synthetic resin having insulating properties, but for example, polyimide, polyvinylformal, thermosetting polyurethane, thermosetting acrylic, epoxy, or thermosetting. Thermosetting resins such as polyester, thermosetting polyesterimide, thermosetting polyesteramideimide, aromatic polyamide, thermosetting polyamideimide, thermosetting polyimide, for example, phenoxy resin, polyether sulfone, polyphenylene sulfide, polyetherimide, polyether Those containing a thermoplastic resin such as ether ketone as a main component can be used. The insulating layer 3 may be a composite or laminated body of two or more kinds of resins, or may be a composite or laminated body of a thermosetting resin and a thermoplastic resin.

(Heat dissipation filler)
The heat-dissipating filler 4 is dispersed in the matrix 2. The material of the heat-dissipating filler 4 includes metal nitrides such as boron nitride, silicon nitride and aluminum nitride, metal carbides such as silicon carbide, titanium carbide, boron carbide and tungsten carbide, beryllium oxide, aluminum oxide, magnesium oxide and oxidation. Examples thereof include metal oxides such as zinc and silicon oxide, spinels, and carbon nanotubes (CNTs). Among these, boron nitride, silicon nitride, aluminum nitride, silicon carbide, aluminum oxide, magnesium oxide, zinc oxide and carbon nanotubes (CNT) having high insulating properties and heat dissipation are preferable, and boron nitride is more preferable because of its low dielectric constant. ..

As the lower limit of the thermal conductivity of the heat-dissipating filler 4 at 25 ° C., 10 W / m · K is preferable, and 20 W / m · K is more preferable. By setting the lower limit of the thermal conductivity of the heat-dissipating filler 4 at 25 ° C. within the above range, the heat-dissipating property of the insulated wire can be further improved.

The shape of the heat-dissipating filler 4 is not particularly limited, and examples thereof include a spherical shape, a scaly shape, and a needle shape. Of these, scaly and needle-shaped are preferable. The scaly and needle-shaped heat-dissipating filler 4 has a relatively high aspect ratio. Therefore, the effect of improving the heat dissipation of the insulating layer 3 can be further enhanced by increasing the heat-dissipating filler 4 whose major axis direction is the thickness direction of the insulating layer 3.

The lower limit of the average particle size of the heat-dissipating filler 4 is preferably 0.1 μm, more preferably 0.2 μm. The upper limit of the average particle size of the heat-dissipating filler 4 is preferably 80.0 μm, more preferably 70.0 μm. If the average particle size of the heat-dissipating filler 4 is less than the above lower limit, the utilization efficiency of the high thermal conductivity of the heat-dissipating filler 4 may decrease, and the heat-dissipating property may not be sufficiently improved. On the contrary, when the average particle size of the heat-dissipating filler 4 exceeds the above upper limit, it may be difficult to apply the resin composition for forming an insulating layer for forming an insulating layer. Here, the average particle size of the heat-dissipating filler 4 is the particle size (D50) corresponding to a cumulative mass percentage of 50% in the particle size distribution measured by the laser diffraction / scattering method.

The lower limit of the content of the heat-dissipating filler 4 with respect to the synthetic resin is preferably 5% by volume, more preferably 10.0% by volume. When the content of the heat-dissipating filler 4 with respect to the synthetic resin is less than the above lower limit, the thermal conductivity of the insulating layer 3 is small, and the heat-dissipating property of the insulated wire may be insufficient. On the other hand, the upper limit of the content of the heat-dissipating filler 4 with respect to the synthetic resin is 60% by volume, more preferably 50% by volume. When the content of the heat-dissipating filler 4 with respect to the synthetic resin exceeds the upper limit, the matrix 2 is relatively small, so that the strength and the fusion property of the insulating layer 3 may be insufficient.

(Cellulose nanofiber)
The cellulose nanofiber 5 is obtained by defibrating and refining a cellulosic fiber as a raw material. Examples of the cellulosic fiber used as a raw material for the cellulosic nanofiber 5 include pulp fibers such as bamboo, straw, and hemp, natural cellulose fibers such as woody pulp fibers such as coniferous and broadleaf trees, rayon, cupra, polynosic, acetate, and the like. Examples thereof include regenerated cellulose fibers, bacterially produced cellulose, and animal-derived cellulose such as squirrel. Further, these celluloses may have a surface chemically modified, if necessary.

The lower limit of the average fiber length of the cellulose nanofibers 5 is preferably 0.10 μm, more preferably 0.15 μm. If the average fiber length of the cellulose nanofibers 5 is less than the above lower limit, the thermal conductivity of the insulating layer 3 may not be sufficiently improved. On the other hand, the upper limit of the fiber length of the cellulose nanofiber 5 is preferably 100.00 μm, more preferably 50.00 μm. If the average fiber length of the cellulose nanofibers 5 exceeds the above upper limit, it may be difficult to uniformly disperse the cellulose nanofibers 5.

The lower limit of the content of the cellulose nanofiber 5 with respect to the synthetic resin is preferably 0.5% by volume, more preferably 1.0% by volume. If the content of the cellulose nanofibers 5 with respect to the synthetic resin does not reach the above lower limit, the thermal conductivity of the insulating layer 3 may not be sufficiently improved. On the other hand, the upper limit of the content of the synthetic resin is preferably 10.0% by volume, more preferably 5.0% by volume, based on the synthetic resin composition. If the content of the cellulose nanofibers 5 exceeds the above upper limit, it may be difficult to uniformly disperse the cellulose nanofibers 5.

<Resin composition for forming an insulating layer>
The resin composition for forming an insulating layer is used for forming an insulating layer of the insulated electric wire. The resin composition for forming an insulating layer is a resin composition for forming an insulating layer used for forming at least one of one or a plurality of insulating layers constituting the insulated wire, and is a synthesis for forming a matrix of the insulating layers. It contains a resin composition, a heat-dissipating filler dispersed in the synthetic resin composition, and cellulose nanofibers dispersed in the synthetic resin composition.

The synthetic resin composition contains the synthetic resin exemplified in the above matrix as a main component. The synthetic resin composition may contain components other than the synthetic resin as long as the effects of the present invention are not impaired. Examples of the other components include various additives such as adhesion improvers, lubricants, antioxidants, light stabilizers, and modifiers, if necessary.

[Manufacturing method of insulated wire of the first embodiment]
The insulated wire of the first embodiment of the present invention includes, for example, a step of preparing a resin composition for forming an insulating layer, a step of applying a resin composition for forming an insulating layer on the outer peripheral surface side of the metal conductor 1, and coating insulation. It can be produced by a production method mainly including a step of drying or curing the layer-forming resin composition.

(Resin composition preparation process for forming an insulating layer)
In the step of preparing the composition for forming an insulating layer, a heat-dissipating filler and cellulose nanofibers are mixed with the synthetic resin composition constituting the matrix of the insulating layer to prepare a resin composition for forming an insulating layer. The synthetic resin composition may be diluted with a solvent before use.

As the solvent for dilution, a known organic solvent used as an insulating varnish can be used. Specifically, for example, polar organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, tetramethylurea, hexaethylphosphate triamide, and γ-butyrolactone are used. First, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as methyl acetate, ethyl acetate, butyl acetate and diethyl oxalate, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl cellosolve). ), Ethers such as diethylene glycol dimethyl ether and tetrahydrofuran, hydrocarbons such as hexane, heptane, benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane and chlorobenzene, phenols such as cresol and chlorophenol, and pyridine and the like. Examples thereof include tertiary amines, and these organic solvents are used alone or in admixture of two or more.

Diluting with such a solvent facilitates application of the resin composition to the conductor. In addition, this solvent volatilizes by heating in the insulating layer forming step.

The lower limit of the resin solid content concentration of the resin composition for forming an insulating layer prepared by diluting with the above organic solvent is preferably 20% by mass, more preferably 22% by mass. Further, the upper limit of the resin solid content concentration of the resin composition for forming an insulating layer is preferably 50% by mass, more preferably 30% by mass. When the resin solid content concentration of the insulating layer forming resin composition is less than the above lower limit, the amount of one coating when applying the insulating layer forming resin composition is small, so that the insulating layer having a desired thickness is applied. There is a risk that the number of repetitions of the process of applying the resin composition for forming an insulating layer for forming the above will increase. On the other hand, when the resin solid content concentration of the insulating layer forming resin composition exceeds the above upper limit, it is difficult to uniformly mix the heat-dissipating filler and the cellulose nanofibers, and the time required for dilution may become long. Here, the resin solid content concentration refers to the concentration of components other than the solvent of the resin composition for forming an insulating layer.

(Resin composition coating process for forming an insulating layer)
In the process of applying the resin composition for forming an insulating layer, the resin composition for forming an insulating layer is applied to the outer peripheral surface side of the metal conductor. As a method of applying the resin composition for forming an insulating layer to the outer peripheral surface side of the metal conductor, for example, a method using a coating device including a liquid composition tank for storing the resin composition for forming an insulating layer and a coating die. Can be mentioned. According to this coating device, the liquid composition adheres to the outer peripheral surface side of the metal conductor by inserting the metal conductor into the liquid composition tank, and then passes through the coating die to make the liquid composition substantially uniform. Apply to thickness.

(Drying or curing process of resin composition for forming an insulating layer)
Resin composition for forming an insulating layer In the drying or curing step, when the resin composition for forming an insulating layer is a thermosetting resin composition, the resin composition for forming an insulating layer is cured by heating to form an insulating layer. To do. When the resin composition for forming an insulating layer is a thermoplastic resin composition, the resin composition for forming an insulating layer is dried by heating to form an insulating layer. The device used for this heating is not particularly limited, but for example, a tubular baking furnace long in the traveling direction of the metal conductor can be used. The heating method is not particularly limited, but in the case of a thermosetting resin composition that can be performed by a conventionally known method such as hot air heating, infrared heating, high frequency heating, etc., the heating temperature is, for example, 300 ° C. or higher and 600 ° C. or lower. Will be done. Further, in the case of the thermoplastic resin composition, the heating temperature is, for example, 100 ° C. or higher and 400 ° C. or lower.

The step of applying the resin composition for forming an insulating layer and the step of drying or curing the resin composition for forming an insulating layer may be repeated a plurality of times. By doing so, the thickness of the insulating layer can be gradually increased. At this time, the hole diameter of the coating die and the number of repetitions are appropriately adjusted according to the diameter of the metal conductor and the target coating film thickness of the insulating layer.

[advantage]
The insulated wire is excellent in heat dissipation because the insulating layer contains a heat dissipation filler and cellulose nanofibers. The resin composition for forming an insulating layer can form an insulating layer having excellent heat dissipation.

<Second Embodiment>
<Insulated wire>
In the insulated wire according to the second embodiment, the insulating layer laminated on the outer peripheral surface of the metal conductor contains a heat-dissipating filler and cellulose nanofibers, and a heat-sealing layer that expands by heating is laminated on the outer peripheral surface of the insulating layer. It is a thing. The insulated wire according to the second embodiment is provided with a heat-sealing layer that expands by heating, and has self-bonding properties in which the heat-sealing layers of the insulated wire are fused to each other, thereby simplifying the motor manufacturing process. Can be planned.

FIG. 2 is a schematic cross-sectional view showing the insulated wire 20 according to the second embodiment. The insulated wire 20 includes a linear metal conductor 1, an insulating layer 3 laminated on the outer peripheral surface of the metal conductor 1, and a heat fusion layer 6 laminated on the outer peripheral surface of the insulating layer 3 to form an outermost layer. And. Since the configurations of the metal conductor 1 and the insulating layer 3 are the same as those of the first embodiment, the same numbers are assigned and the description thereof will be omitted.

(Heat fusion layer)
The heat-sealing layer 6 has a matrix 7 and a foaming agent 8 dispersed in the matrix 7. The heat-sealing layer 6 expands by heating. In the insulated wire 20 according to the second embodiment of the present invention, the gap between the winding and the motor can be filled more densely by foaming the foaming agent 8 dispersed in the matrix 7 of the heat fusion layer 6. The heat dissipation can be further improved.

The lower limit of the average thickness of the heat-sealing layer 6 before heating is preferably 10 μm, more preferably 20 μm. On the other hand, the upper limit of the average thickness of the heat-sealing layer 6 before heating is preferably 300 μm, more preferably 200 μm. If the average thickness of the heat-sealing layer 6 before heating is less than the above lower limit, the insulated wires may not be sufficiently adhered to each other. On the contrary, when the average thickness of the heat-sealing layer 6 before heating exceeds the above upper limit, the volumetric efficiency of the windings and the like formed by using the insulated wire may decrease.

The lower limit of the average diameter of the pores formed in the heat-sealing layer 6 by foaming the foaming agent 8 by heating is preferably 1 μm, more preferably 5 μm. On the other hand, the upper limit of the average diameter of the pores formed in the heat-sealing layer 6 is preferably 200 μm, more preferably 100 μm. If the average diameter of the pores formed in the heat-sealing layer 6 is less than the lower limit, a sufficient expansion coefficient may not be obtained. On the contrary, when the average diameter of the pores formed in the heat-sealing layer 6 exceeds the upper limit, the heat-sealing layer 6 may become unnecessarily thick and the expansion of the heat-sealing layer 6 becomes uneven. There is a risk of becoming. Here, the "average diameter of pores" 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" of Porous Materials).

The lower limit of the porosity of the heat-sealed layer 6 after heating is preferably 10.0% by volume, more preferably 50% by volume. On the other hand, the upper limit of the porosity of the heat-sealed layer 6 after heating is preferably 80%, more preferably 70%. If the porosity of the heat-sealing layer 6 after heating is less than the above lower limit, the contact pressure between the adjacent heat-sealing layers 6 may be insufficient and the fusion may be insufficient. On the contrary, when the porosity of the heat-sealing layer 6 after heating exceeds the above upper limit, the strength of the heat-sealing layer 6 after expansion may be insufficient. Here, the "porosity" of the heat-sealed layer is a percentage of the volume of gas in the heat-sealed layer with respect to the volume of the heat-sealed layer, and is a solid content such as a matrix of the heat-sealed layer and a foaming agent. When the actual volume calculated from the mass and the density is V0 and the apparent volume including the voids of the heat-sealing layer is V1, the amount is calculated by (V1-V0) / V1 × 100.

The lower limit of the average thickness expansion coefficient of the heat-sealed layer 6 after heating is preferably 1.2 times, more preferably 1.5 times. On the other hand, the upper limit of the average thickness expansion coefficient of the heat-sealed layer 6 after heating is preferably 4 times, more preferably 3 times. When the average thickness expansion coefficient of the heat-sealing layer 6 after heating is less than the above lower limit, the heat-sealing layers 6 adjacent to each other are not fused when the self-bonding insulated wire is wound. May be sufficient. On the contrary, when the average thickness expansion coefficient of the heat-sealing layer 6 after heating exceeds the above upper limit, the density of the heat-sealing layer 6 becomes insufficient, and the strength of the self-bonding insulated wire is rather insufficient. May be sufficient. The expansion coefficient of the heat-sealing layer 6 can be controlled by selecting the type and amount of the foaming agent 8 and the elastic modulus of the matrix 7 at the foaming start temperature of the foaming agent 8.

(matrix)
As the synthetic resin that is the main component of the resin composition constituting the matrix 7, a thermoplastic resin such as a phenoxy resin, a polyamide, or a butyral resin can be used, and among them, the phenoxy resin is preferably used. Further, the resin composition constituting the matrix 7 may contain additives such as an adhesion improver.

Phenoxy resin is a thermoplastic resin synthesized from bisphenols and epichlorohydrin and having epoxy groups at both ends. Examples of the phenoxy resin include bisphenol A-type phenoxy resin, bisphenol F-type phenoxy resin, bisphenol S-type phenoxy resin, and bisphenol B-type phenoxy resin. Further, as the phenoxy resin, a copolymerized phenoxy resin such as a phenoxy resin obtained by copolymerizing bisphenol A type and bisphenol S type can also be used. Furthermore, by using a cross-linking agent such as an amino resin or isocyanate in combination with the phenoxy resin, it can also be used as a thermosetting resin. By using a phenoxy resin and a cross-linking agent in combination to form a thermosetting resin, sufficient strength of the heat-sealing layer 6 is ensured when the heat-expandable microcapsules are also contained in the heat-sealing layer 6. be able to.

As the above-mentioned polyamide, for example, various polycondensation polyamides, various co-condensation polymerized polyamides and the like can be used.

Examples of the butyral resin include polyvinyl butyral and the like.

Examples of other thermoplastic resins that can be used as the synthetic resin that is the main component of the resin composition constituting the matrix 7 include copolymerized polyester, polybutylene terephthalate, polyethylene terephthalate, thermoplastic polyurethane, polycarbonate, polyphenylene oxide, and polyphenylene sulfide. , Polyetherimide, polyetheretherketone, polyetherketone, polyethersulfone, polyphenylsulphon, semi-aromatic polyamide, thermoplastic polyamideimide, thermoplastic polyimide and the like.

(Foaming agent)
As the foaming agent 8, a chemical foaming agent or a physical foaming agent can be used.

As the lower limit of the content of the foaming agent 8 with respect to 100 parts by mass of the synthetic resin, 2 parts by mass is preferable, and 3 parts by mass is more preferable. If the content of the foaming agent 8 with respect to 100 parts by mass of the synthetic resin is less than the above lower limit, the expansion coefficient of the heat-sealing layer 6 is small, and the insulating wires may not be sufficiently fixed to each other. On the other hand, the upper limit of the content of the foaming agent 8 with respect to 100 parts by mass of the synthetic resin is preferably 40 parts by mass, more preferably 30 parts by mass. When the content of the foaming agent 8 with respect to 100 parts by mass of the synthetic resin exceeds the above upper limit, the strength and the cohesiveness of the heat-sealing layer 6 may be insufficient due to the relatively small amount of the matrix 7. ..

<Chemical foaming agent>
The chemical foaming agent used as the foaming agent 8 decomposes by a chemical reaction to generate, for example, nitrogen gas, carbon dioxide gas, carbon monoxide, ammonia gas and the like. Examples of the chemical foaming agent include an organic foaming agent and an inorganic foaming agent. Generally, an inorganic foaming agent has a slower gas generation rate than an organic foaming agent, and it is difficult to adjust gas generation. Therefore, an organic foaming agent is preferable as a chemical foaming agent.

Examples of the organic foaming agent include azo foaming agents such as azodicarboxylic amide and azobisisobutyronitrile, and nitroso foaming agents such as dinitrosopentamethylenetetramine, N, N'dinitroso-N, N'-dimethylterephthalamide. Examples thereof include hydrazide-based foaming agents such as p-toluenesulfonyl hydrazide, p, p'-oxybisbenzenesulfonylhydrazide, benzenesulfonylhydrazide, and trihydradinotriazine, which may be used alone or in two types. The above can be used together.

Examples of the inorganic foaming agent include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium borohydride, silicon oxyhydride and the like.

The lower limit of the decomposition temperature of the chemical foaming agent is preferably 60 ° C., more preferably 70 ° C. On the other hand, the upper limit of the decomposition temperature of the chemical foaming agent is preferably 250 ° C., more preferably 200 ° C. If the decomposition temperature of the chemical foaming agent is less than the above lower limit, the chemical foaming agent may unintentionally foam during manufacturing, transportation, or storage of the insulated wire. On the other hand, if the decomposition temperature of the chemical foaming agent exceeds the above upper limit, the energy cost required for foaming the foaming agent may become excessive.

A foaming aid may be blended with the chemical foaming agent in the heat-sealing layer 6. The foaming aid is not particularly limited as long as it promotes the thermal decomposition of the chemical foaming agent, and examples thereof include urea compounds.

As the lower limit of the blending amount of these foaming aids with respect to 100 parts by mass of the chemical foaming agent, 5 parts by mass is preferable, and 50 parts by mass is more preferable. On the other hand, the upper limit of the blending amount of the foaming aid is preferably 200 parts by mass, more preferably 150 parts by mass. If the blending amount of the foaming aid is less than the above lower limit, the effect of decomposing the chemical foaming agent may be insufficient. On the contrary, when the blending amount of the foaming aid exceeds the upper limit, the heat-sealing layer 6 may unintentionally expand during the production or storage of the insulated wire.

<Physical foaming agent>
The physical foaming agent used as the foaming agent 8 is foamed by utilizing the gas generated by the vaporization of the foaming agent. Examples of the physical foaming agent include heat-expandable microcapsules. The heat-expandable microcapsules have a core material (inclusion) 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. The thermal expansion microcapsules can promote relatively uniform expansion of the heat-sealing layer 6 by forming bubbles independently of the individual microcapsules.

The internal foaming agent of the heat-expandable microcapsules may be any one that expands or generates a gas by heating, and the principle thereof is not limited. As the internal foaming agent of the heat-expandable microcapsules, for example, a low boiling point liquid can be used.

As the low boiling point liquid, for example, alkanes such as butane, i-butane, n-pentane, i-pentane, and neopentane, and chlorofluorocarbons such as trichlorofluoromethane are preferably used.

The lower limit of the expansion temperature of the heat-expandable microcapsules is preferably 60 ° C, more preferably 70 ° C. On the other hand, the upper limit of the expansion temperature of the heat-expandable microcapsules is preferably 250 ° C., more preferably 200 ° C. If the expansion temperature of the heat-expandable microcapsules is less than the above lower limit, the heat-expandable microcapsules may unintentionally expand during manufacturing, transportation, or storage of the insulated wire. On the contrary, when the expansion temperature of the heat-expandable microcapsules exceeds the above upper limit, the energy cost required for expanding the heat-expandable microcapsules may become excessive.

On the other hand, the outer shell of the heat-expandable microcapsules is formed of a stretchable material capable of forming a microballoon containing the generated gas by expanding without breaking when the internal foaming agent is expanded. As a material for forming the outer shell of the heat-expandable microcapsules, a resin composition containing a polymer such as a thermoplastic resin as a main component is usually used.

The thermoplastic resin which is the main component of the outer shell of the heat-expandable microcapsule is formed of a monomer such as vinyl chloride, vinylidene chloride, acrylonitrile, acrylic acid, methacrylic acid, acrylate, methacrylate, and styrene. A polymer or a copolymer formed from two or more kinds of monomers is preferably used. An example of a preferable thermoplastic resin is an acrylonitrile-based copolymer, and the decomposition temperature of the internal foaming agent in this case is 70 ° C. or higher and 250 ° C. or lower.

The lower limit of the average diameter of the heat-expandable microcapsules before heating is preferably 1 μm, more preferably 5 μm. On the other hand, the upper limit of the average diameter of the heat-expandable microcapsules before heating is preferably 50 μm, more preferably 40 μm. If the average diameter of the thermally expandable microcapsules before heating is less than the above lower limit, a sufficient expansion coefficient may not be obtained. On the contrary, when the average diameter of the heat-expandable microcapsules before heating exceeds the above upper limit, the heat-sealing layer 6 may become unnecessarily thick, or the expansion of the heat-sealing layer 6 may become non-uniform. .. The "average diameter" of the heat-expandable microcapsules is the average value of the maximum diameter in a plan view when 10 or more samples of the heat-expandable microcapsules are observed under a microscope and the diameter in a direction orthogonal to the maximum diameter. It shall be said.

The lower limit of the ratio of the average diameter of the heat-expandable microcapsules to the average thickness of the heat-sealed layer 6 is preferably 1/16, more preferably 1/8. On the other hand, as the upper limit of the ratio of the average diameter of the heat-expandable microcapsules to the average thickness of the heat-sealed layer 6, 9/10 is preferable, and 8/10 is more preferable. If the average diameter of the heat-expandable microcapsules is less than the above lower limit, the thickness of the outer shell may be insufficient and the microcapsules may be torn during expansion, or the internal volume may be small and the foaming agent may be insufficient to sufficiently expand. On the contrary, when the average diameter of the heat-expandable microcapsules exceeds the above upper limit, the heat-expandable microcapsules may protrude from the matrix 7 and the heat-sealing layer 6 may not be sufficiently expanded, or the heat-sealing layer 6 may not be sufficiently expanded. May partially expand and may not expand uniformly.

The lower limit of the expansion coefficient of the heat-expandable microcapsules is preferably 3 times, more preferably 5 times. On the other hand, the upper limit of the expansion coefficient of the heat-expandable microcapsules is preferably 20 times, more preferably 10 times. If the expansion coefficient of the heat-expandable microcapsules is less than the above lower limit, the expansion coefficient of the heat-sealing layer 6 may be insufficient. On the contrary, when the expansion coefficient of the heat-expandable microcapsules exceeds the above upper limit, the matrix 7 of the heat-sealing layer 6 cannot follow the heat-expandable microcapsules, and the heat-sealing layer 6 is expanded as a whole. It may not be possible to do so. The "expansion rate" of the heat-expandable microcapsules refers to the ratio of the maximum value of the average diameter after heating to the average diameter of the heat-expandable microcapsules before heating.

[Manufacturing method of insulated wire of the second embodiment]
Examples of the method for producing an insulated electric wire according to the second embodiment of the present invention include a step of preparing a resin composition for forming an insulating layer, a step of applying a resin composition for forming an insulating layer, and a step of drying a resin composition for forming an insulating layer. Alternatively, after performing the curing step, a step of applying the heat-sealing layer-forming resin composition to the outer peripheral surface side of the dried or cured insulating layer-forming resin composition and a heat-sealing layer-forming resin composition are applied. Examples include a drying process and a method of preparing.

(Resin composition coating process for forming a heat-sealing layer)
In the process of applying the resin composition for forming a heat-sealing layer, the foaming agent 8 is dispersed in a solution obtained by diluting the resin composition constituting the matrix 7 with a solvent to prepare a resin composition for forming a heat-sealing layer. As a method of dispersing the foaming agent 8 in the resin composition, for example, it can be carried out by mixing using a stirring pot, a three-roll mill or the like. Then, the resin composition for forming the heat-sealing layer is applied to the outer peripheral surface side of the insulating layer 3. The method for applying the resin composition for forming a heat-sealing layer can be the same as the above-mentioned step for applying the resin composition for forming an insulating layer.

(Drying step of resin composition for forming heat-sealing layer)
In the process of drying the resin composition for forming a heat-sealing layer, the resin composition for forming a heat-sealing layer is dried by evaporating the solvent at a temperature lower than the expansion start temperature of the foaming agent 8, and the heat-sealing layer is formed. 6 is formed. As the drying method, conventionally known methods such as hot air heating, infrared heating, and high frequency heating can be used.

As a heating method for expanding the heat-sealing layer 6, in addition to conventionally known methods such as hot air heating, infrared heating, and high frequency heating, a method using heat generated by energizing the metal conductor 1 can be applied.

Further, the method for manufacturing the insulated wire is not limited to the above method. For example, when the main component of the insulating layer is a thermoplastic resin, a method of diluting with a solvent and drying as in the method of laminating the heat-sealing layer, or a method of applying the molten resin composition with a coating die is applied. A method of cooling and curing can be applied.

[advantage]
Since the insulated wire has a heat-sealing layer that expands by heating and has self-bonding properties that fuse with each other on the outer periphery of the metal conductor, the motor manufacturing process can be simplified. Further, since the insulating layer contains a heat-dissipating filler and cellulose nanofibers, the heat-dissipating property is excellent.

[Other Embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not limited to the configuration of the above embodiment, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. To.

In the above embodiment, one insulating layer containing a heat-dissipating filler and cellulose nanofibers is thermally fused to an insulating electric wire in which one layer is laminated on the outer peripheral surface of a metal conductor and an outer peripheral surface of an insulating layer containing the heat-dissipating filler and cellulose nanofibers. Although the insulated wire on which the layers are laminated has been described, a plurality of insulating layers may be laminated between the metal conductor and the insulating layer containing the heat-dissipating filler and the cellulose nanofibers. In other words, in an insulated wire in which a plurality of insulating layers are laminated, it is sufficient that at least one insulating layer contains cellulose nanofibers. Further, cellulose nanofibers may be contained in two or more insulating layers.

Further, for example, in the insulated wire, a further layer such as a primer-treated layer may be provided between the metal conductor and the insulating layer. The primer-treated layer is a layer provided for enhancing the adhesion between layers, and can be formed by, for example, a known resin composition.

When a primer-treated layer is provided between the metal conductor and the insulating layer, the resin composition forming the primer-treated layer is, for example, one or more resins among polyimide, polyamide-imide, polyesterimide, polyester and phenoxy resins. May be included. Further, the resin composition forming the primer-treated layer may contain an additive such as an adhesion improver. By forming a primer-treated layer between the metal conductor and the insulating layer with such a resin composition, it is possible to improve the adhesion between the metal conductor and the insulating layer, and as a result, the insulation. It is possible to effectively enhance the flexibility of the electric wire and the characteristics such as abrasion resistance, scratch resistance, and work resistance.

Further, the resin composition forming the primer-treated layer may contain other resins such as epoxy resin and melamine resin together with the above resin. Further, a commercially available liquid composition (insulating varnish) may be used as each resin contained in the resin composition forming the primer-treated layer.

The lower limit of the average thickness of the primer-treated layer is preferably 1 μm, more preferably 2 μm. On the other hand, the upper limit of the average thickness of the primer-treated layer is preferably 20 μm, more preferably 10 μm. If the average thickness of the primer-treated layer is less than the above lower limit, sufficient adhesion to the metal conductor may not be exhibited. On the contrary, if the average thickness of the primer-treated layer exceeds the above upper limit, the diameter of the insulated wire may be unnecessarily increased.

Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limitedly interpreted based on the description of this Example.

<Insulated wire No. 1-No. 16>
By laminating an insulating layer having an average thickness of 40 μm on a copper wire having a diameter of 1 mm, the insulated wire No. 1-No. 16 was prototyped. For the insulating layer, the resin composition for forming an insulating layer having the compositions shown in Tables 1 and 2 is applied with a coating die, and the furnace temperature is 200 ° C. and the linear speed is 4.8 m / min using a horizontal furnace having a furnace length of 3 m. It was dried (baked) under the conditions.

[Resin composition for forming an insulating layer]
(Resin component)
As the resin component of the matrix of the composition for forming the insulating layer, a phenoxy resin having a glass transition temperature of 130 ° C. (“YP-50” of Nippon Steel & Sumikin Chemical Co., Ltd.) was used.

(Cellulose nanofiber)
As the cellulose nanofibers, "Binphis" manufactured by Sugino Machine Limited, which is made of natural cellulose and has an average fiber length of 1 μm to 5 μm, was used.

(Heat dissipation filler)
The heat-dissipating filler of the resin composition for forming an insulating layer includes boron nitride (“MBN-010T” by Mitsui Chemicals, Inc.) and spherical alumina (“AO-502” by Admatex, Inc.) having a thermal conductivity of 60 W / m · K. ") Was used.

Among the resin compositions for forming an insulating layer used for forming the insulating layer of each insulated wire, Table 1 shows the composition of the resin composition for forming an insulating layer containing scaly boron nitride as a heat-dissipating filler, and the heat-dissipating property is shown in Table 1. Table 2 shows the composition of the resin composition for forming an insulating layer containing spherical alumina as a filler. In addition, "-" in Table 1 and Table 2 indicates that the corresponding component was not used.

[Evaluation of thermal conductivity of insulating layer]
The thermal conductivity of the insulating layer of each insulated wire was evaluated. Specifically, the insulated wire No. 1-No. The thermal conductivity at 25 ° C. was measured by measuring the thermal diffusivity, specific heat and density of the 16 insulating layers. The measurement results are shown in Tables 1 and 2.

As shown in Table 1 above, the insulated wire No. 1 containing boron nitride and cellulose nanofibers, which are heat-dissipating fillers. 8 to No. The insulating layer of No. 10 contains an insulating wire No. 10 containing neither a heat-dissipating filler nor cellulose nanofibers. Insulated wire No. 1 containing only one of the insulating layer of 1 and boron nitride and cellulose nanofibers. 2-No. The thermal conductivity was excellent as compared with the insulating layer of No. 7.

Further, as shown in Table 2 above, the insulated wire No. 1 containing spherical alumina and cellulose nanofibers which are heat-dissipating fillers. 14-No. The insulating layer of No. 16 contains an insulated wire No. 16 containing neither spherical alumina nor cellulose nanofibers. Insulated wire No. 1 containing only one of the insulating layer of 1 and spherical alumina and cellulose nanofibers. 2-No. 4 and No. 11-No. The thermal conductivity was excellent as compared with the insulating layer of 13.

As described above, in the insulated wire, the thermal conductivity of the insulating layer is improved by having the heat-dissipating filler and the cellulose nanofibers in the matrix in which the insulating layer is mainly composed of synthetic resin, and the heat-dissipating property is excellent. Shown.

The insulated wire according to the present invention can be suitably used for forming windings, motors, and the like.

1 Metal conductor 2 Insulation layer matrix 3 Insulation layer 4 Heat dissipation filler 5 Cellulose nanofibers 6 Heat fusion layer 7 Heat fusion layer matrix 8 Foaming agent 10, 20 Insulation wire

Claims (4)

An insulated wire having a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor.
The above insulating layer
A matrix whose main component is synthetic resin,
With the heat-dissipating filler dispersed in the above matrix,
It has cellulose nanofibers dispersed in the above matrix.
The content of the heat-dissipating filler with respect to 100 parts by volume of the synthetic resin is 40 parts by volume or more and 60 parts by volume or less.
The thermal conductivity of the heat-dissipating filler at 25 ° C. is 60 W / m · K or more.
The average particle size of the heat-dissipating filler is 0.1 μm or more and 80 μm or less.
The content of the cellulose nanofibers with respect to 100 parts by volume of the synthetic resin is 2.0 parts by volume or more and 10.0 parts by volume or less.
The average fiber length of the cellulose nanofibers Ri der 1 [mu] m or more 5 [mu] m or less,
The above synthetic resin is a phenoxy resin,
Insulated wire the heat dissipation filler Ru der boron nitride. The insulated wire according to claim 1, wherein the heat-dissipating filler is scaly or needle-shaped. A resin composition for forming an insulating layer used for forming at least one of one or a plurality of insulating layers constituting an insulated wire.
The synthetic resin composition forming the matrix of the insulating layer and
With the heat-dissipating filler dispersed in the synthetic resin composition,
Contains cellulose nanofibers dispersed in the synthetic resin composition,
The content of the heat-dissipating filler with respect to 100 parts by volume of the synthetic resin is 40 parts by volume or more and 60 parts by volume or less.
The thermal conductivity of the heat-dissipating filler at 25 ° C. is 60 W / m · K or more.
The average particle size of the heat-dissipating filler is 0.1 μm or more and 80 μm or less.
The content of the cellulose nanofibers with respect to 100 parts by volume of the synthetic resin is 2.0 parts by volume or more and 10.0 parts by volume or less.
The average fiber length of the cellulose nanofibers Ri der 1 [mu] m or more 5 [mu] m or less,
The above synthetic resin is a phenoxy resin,
The heat dissipation filler is Ru der boron nitride insulating layer-forming resin composition. A method for manufacturing an insulated electric wire including a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor.
A step of diluting the synthetic resin composition constituting the matrix of the insulating layer with a solvent and mixing a heat-dissipating filler and cellulose nanofibers to prepare a resin composition for forming an insulating layer.
The step of applying the resin composition for forming an insulating layer to the outer peripheral surface side of the metal conductor, and
A step of heating the resin composition for forming an insulating layer is provided.
The resin solid content concentration of the insulating layer forming resin composition prepared by diluting with the solvent in the adjustment step is 20 parts by mass or more and 50 parts by mass or less.
The content of the heat-dissipating filler with respect to 100 parts by volume of the synthetic resin is 40 parts by volume or more and 60 parts by volume or less.
The thermal conductivity of the heat-dissipating filler at 25 ° C. is 60 W / m · K or more.
The average particle size of the heat-dissipating filler is 0.1 μm or more and 80 μm or less.
The content of the cellulose nanofibers with respect to 100 parts by volume of the synthetic resin is 2.0 parts by volume or more and 10.0 parts by volume or less.
The average fiber length of the cellulose nanofibers Ri der 1 [mu] m or more 5 [mu] m or less,
The above synthetic resin is a phenoxy resin,
Method of manufacturing an insulated wire the heat dissipation filler is Ru boron nitride der.

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