JP6923493B2 - Insulated wire - Google Patents

Description

The present invention relates to an insulated electric wire.

For example, when manufacturing a coil for a motor using an insulated wire, after winding the wire around the core, the gap between the wires and the gap between the wires and the core are impregnated with varnish to fix the wires and the wires to the core. Is common (see JP-A-2010-238662).

Japanese Unexamined Patent Publication No. 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 includes a linear metal conductor, an insulating layer laminated on the outer peripheral surface side of the metal conductor, and the outer peripheral surface side of the insulating layer. An insulated wire having a heat-sealing layer laminated on the outermost side and expanding by heating, wherein the heat-sealing layer is a matrix containing a synthetic resin as a main component and a plate-like or scale dispersed in the matrix. It has a heat-dissipating filler in the form and a foaming agent dispersed in the matrix, and the content of the heat-dissipating filler with respect to the synthetic resin is 10% by volume or more and 60% by volume or less.

The insulated wire according to one aspect of the present invention has excellent heat dissipation.

It is a schematic cross-sectional view which shows the insulated wire of one Embodiment of this invention.

[Explanation of Embodiments of the Present Invention]
The insulated wire according to one aspect of the present invention includes a linear metal conductor, an insulating layer laminated on the outer peripheral surface side of the metal conductor, and an insulating layer laminated on the outer peripheral surface side and the outermost side of the insulating layer, and expands by heating. An insulated wire including a heat-sealing layer, wherein the heat-sealing layer contains a matrix containing a synthetic resin as a main component, a plate-shaped or scaly heat-dissipating filler dispersed in the matrix, and the matrix. It has a foaming agent dispersed therein, and the content of the heat-dissipating filler with respect to the synthetic resin is 10% by volume or more and 60% by volume or less.

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. Then, since the heat-dissipating filler in which the heat-sealing layer is dispersed in the matrix is plate-shaped or scaly, the heat-dissipating filler is folded over the heat-sealing layer along the thickness direction of the heat-sealing layer. Orientate. Further, the heat-sealing layer has a heat-dissipating filler and a foaming agent dispersed in the matrix, and the content of the heat-dissipating filler with respect to the synthetic resin is 10% by volume or more and 60% by volume or less. Due to the foaming of the heat-dissipating filler, the orientation of the plate-like or scaly heat-dissipating filler is disturbed in the radial direction of the insulated wire. Therefore, as a result of increasing the heat conduction path to the surface side of the insulated wire, the heat conductivity of the heat-sealed layer is improved. Therefore, the insulated wire has excellent heat dissipation. Further, the insulated wire can fill the gap between the winding and the motor more densely by foaming the foaming agent dispersed in the matrix of the heat fusion layer, so that the heat dissipation can be further improved. Here, 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 foaming agent with respect to 100 parts by mass of the synthetic resin is preferably 3 parts by mass or more and 30 parts by mass or less. By setting the content of the foaming agent within the above range in this way, the heat dissipation of the insulated wire can be further improved.

The thermal conductivity of the heat-dissipating filler at 25 ° C. is preferably 20 W / m · K or more. By setting the thermal conductivity of the heat-dissipating filler at 25 ° C. within the above range, the heat-dissipating property of the insulated wire can be further improved.

The porosity of the heat-sealed layer after heating is preferably 10% or more and 80% or less. By setting the porosity of the heat-sealed layer after heating within the above range in this way, the continuity of the matrix of the heat-sealed layer at the time of expansion is ensured, and the heat-sealed layers are fused to each other. The reliability can be further improved.

Therefore, the winding using the insulated wire can be applied to an electric device having a high applicable voltage such as a motor used at a high voltage.

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

<Insulated wire>
FIG. 1 is a schematic cross-sectional view showing an insulated wire according to an embodiment of the present invention. As shown in FIG. 1, the insulated wire 10 is laminated on a linear metal conductor 1, an insulating layer 2 laminated on the outer peripheral surface side of the metal conductor 1, and an outer peripheral surface side of the insulating layer 2, and is heated by heating. It includes an expanding heat-sealing layer 3.

[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, 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, a nickel-coated copper wire, a silver-coated copper wire, or a copper-coated material. Aluminum wire, copper-coated steel wire, etc. 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, 100 mm ² is preferable, and 50 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 heat-sealing 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 coil can be formed relatively easily and inexpensively even by the method of impregnating the conventional insulated wire with varnish, which is advantageous over the conventional insulated wire. It may not be obtained.

[Insulation layer]
The insulating layer 2 is formed of a resin composition having an insulating property. The resin composition forming the insulating layer 2 is not particularly limited, and is, for example, polyimide, polyvinylformal, thermosetting polyurethane, thermosetting acrylic, epoxy, thermosetting polyester, thermosetting polyesterimide, thermosetting polyesteramideimide, and aromatic. Thermosetting resins such as polyamide, thermosetting polyamideimide, and thermosetting polyimide, and those containing mainly thermoplastic resins such as phenoxy resin, polyether sulfone, polyphenylene sulfide, polyetherimide, and polyether ether ketone are used. can. The insulating layer 2 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.

As the lower limit of the average thickness of the insulating layer 2, 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 2 is preferably 200 μm, more preferably 150 μm. If the average thickness of the insulating layer 2 is less than the above lower limit, the insulating layer 2 may be torn and the insulation of the metal conductor 1 may be insufficient. On the contrary, when the average thickness of the insulating layer 2 exceeds the above upper limit, the volumetric efficiency of the coil or the like formed by using the insulated wire may be lowered.

[Heat fusion layer]
The heat-sealing layer 3 has a matrix 4 containing a synthetic resin as a main component, a foaming agent 5 dispersed in the matrix 4, and a plate-shaped or scaly heat-dissipating filler 6. FIG. 1 shows an insulated wire in a state before the foaming agent is fired.

The heat-sealing layer 3 expands as the foaming agent 5 expands when heated, and expands as a whole. 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. In the insulated wire, the gap between the winding and the motor can be filled more densely by foaming the foaming agent dispersed in the matrix of the heat fusion layer, so that the heat dissipation can be further improved.

The lower limit of the average thickness of the heat-sealing layer 3 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 3 before heating is preferably 300 μm, more preferably 200 μm. If the average thickness of the heat-sealing layer 3 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-sealed layer 3 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 thermal conductivity of the heat-sealed layer after foaming at 25 ° C. in the thickness direction is preferably 0.25 W / m · K, more preferably 0.30 W / m · K, and 0.35 W / m · K. K is more preferred. If the thermal conductivity of the insulating layer 2 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.

The lower limit of the average diameter of the pores formed in the heat-sealing layer 3 by the foaming of the foaming agent 5 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 3 is preferably 200 μm, more preferably 100 μm. If the average diameter of the pores formed in the heat-sealing layer 3 is less than the above lower limit, a sufficient expansion rate may not be obtained. On the contrary, when the average diameter of the pores formed in the heat-sealing layer 3 exceeds the upper limit, the heat-sealing layer 3 may become unnecessarily thick and the expansion of the heat-sealing layer 3 becomes uneven. There is a risk of becoming. Here, the "average diameter of the pores" is a value obtained by measuring the 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 3 after heating is preferably 10% by volume, more preferably 50% by volume. On the other hand, the upper limit of the porosity of the heat-sealed layer 3 after heating is preferably 80%, more preferably 70%. If the porosity of the heat-sealing layer 3 after heating is less than the above lower limit, the contact pressure between the adjacent heat-sealing layers 3 may be insufficient and the fusion may be insufficient. On the contrary, when the porosity of the heat-sealed layer 3 after heating exceeds the above upper limit, the strength of the heat-sealed layer 3 after expansion may be insufficient. Here, the "porosity" of the heat-sealed layer is a percentage of the volume of the gas in the heat-sealed layer with respect to the volume of the heat-sealed layer, and is a matrix of the heat-sealed layer, a heat-dissipating filler, a foaming agent, or the like. When the actual volume calculated from the mass and density of the solid content 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 3 after heating is preferably 1.3 times, more preferably 1.5 times. On the other hand, the upper limit of the average thickness expansion coefficient of the heat-sealed layer 3 after heating is preferably 4 times, more preferably 3 times. When the average thickness expansion rate of the heat-sealing layer 3 after heating is less than the above lower limit, the heat-sealing layers 3 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 rate of the heat-sealing layer 3 after heating exceeds the above upper limit, the density of the heat-sealing layer 3 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 3 can be controlled by selecting the type and amount of the foaming agent 5 and the elastic modulus of the matrix 4 at the foaming start temperature of the foaming agent.

(matrix)
As the synthetic resin that is the main component of the resin composition constituting the matrix 4, 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.

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, the strength of the expansion layer can be sufficiently ensured even when the heat-expandable microcapsules that form relatively large pores are used.

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.

Other thermoplastic resins that can be used as the synthetic resin that is the main component of the resin composition constituting the matrix 4 include, for example, copolymerized polyester, polybutylene terephthalate, polyethylene terephthalate, thermoplastic polyurethane, polycarbonate, polyphenylene oxide, and polyphenylene sulfide. , Polyetherketone, polyetherimide, polyetheretherketone, polyetherketone, polyethersulphon, polyphenylsulphon, semi-aromatic polyamide, thermoplastic polyamideimide, thermoplastic polyimide and the like.

The resin composition constituting the matrix 4 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, and light stabilizers, and general various additives such as modifiers, if necessary.

(Heat-dissipating filler)
The heat-dissipating filler has a plate-like or scaly shape. Since the heat-dissipating filler has a plate-like or scaly shape, the heat-dissipating filler is oriented so as to fold in the thickness direction of the heat-sealing layer, so that the contact area between the heat-dissipating fillers becomes large and the heat-dissipating property becomes more excellent. improves.

Examples of the heat-dissipating filler include boron nitride and scaly alumina. Among these, boron nitride having insulating properties and high thermal conductivity is preferable.

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

The lower limit of the content of the heat-dissipating filler 6 with respect to the synthetic resin is 10% by volume, preferably 20% by volume. If the content of the heat-dissipating filler 6 with respect to the synthetic resin is less than the above lower limit, the thermal conductivity of the heat-sealing 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 with respect to the synthetic resin is 60% by volume, more preferably 50% by volume. When the content of the heat-dissipating filler 6 with respect to the synthetic resin exceeds the above upper limit, the strength and the cohesiveness of the heat-sealing layer 3 may be insufficient due to the relatively small amount of the matrix 4.

The lower limit of the average particle size of the heat-dissipating filler is preferably 10 μm, more preferably 15 μm. On the other hand, the upper limit of the average particle size of the heat-dissipating filler is preferably 30 μm, more preferably 25 μm. If the average particle size of the heat-dissipating filler is less than the above lower limit, the utilization efficiency of the high thermal conductivity of the heat-dissipating filler 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 exceeds the upper limit, it becomes difficult to apply the heat-sealing composition forming the heat-sealing layer, and the heat-sealing layer 3 on the outer peripheral surface side of the conductor becomes difficult to apply. Covering may be difficult. Here, the average particle size of the plate-shaped or scaly heat-dissipating filler 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. Is.

The lower limit of the average thickness of the heat-dissipating filler is preferably 0.1 μm, more preferably 0.2 μm. On the other hand, the upper limit of the average thickness of the heat-dissipating filler is preferably 5 μm, more preferably 2 μm. If the average thickness of the heat-dissipating filler is less than the above lower limit, the heat-dissipating filler may be damaged when mixed with the binder. On the contrary, if the average thickness of the heat-dissipating filler exceeds the upper limit, it is difficult to finely disperse the heat-dissipating filler in the entire synthetic resin, and a sufficient heat-dissipating effect may not be exhibited. The average thickness means the average length in the thickness direction (Z direction) with respect to the major axis and the minor axis in the main surface (X direction, Y direction) of the plate-shaped or scaly heat-dissipating filler. Further, the fine dispersion means a state in which the heat-dissipating filler is dispersed in the synthetic resin without substantially agglutinating.

The lower limit of the aspect ratio (average particle size / average thickness), which is the value obtained by dividing the average particle size of the heat-dissipating filler by the average thickness, is preferably 10 and more preferably 20. On the other hand, as the upper limit of the aspect ratio, 200 is preferable, and 100 is more preferable. If the aspect ratio is less than the above lower limit, it becomes difficult for the heat-dissipating filler to be oriented in the same direction in the heat-sealing layer 3, and the heat-dissipating property may not be sufficiently improved. On the contrary, when the aspect ratio exceeds the upper limit, the strength of the heat-dissipating filler is lowered, and the heat-dissipating filler may be damaged when mixed with the binder.

(Foaming agent)
As the foaming agent 5, a chemical foaming agent or a physical foaming agent can be used.

As the lower limit of the content of the foaming agent 5 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 5 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 3 is small, and the insulating wires may not be sufficiently adhered to each other. On the other hand, as the upper limit of the content of the foaming agent 5 with respect to 100 parts by mass of the synthetic resin, 40 parts by mass is preferable, and 30 parts by mass is more preferable. When the content of the foaming agent 5 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 3 may be insufficient due to the relatively small amount of the matrix 4. ..

<Chemical foaming agent>
The chemical foaming agent used as the foaming agent 5 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. In general, 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, and N'-dimethylterephthalamide. Examples thereof include hydrazide-based foaming agents such as p-toluenesulfonyl hydrazide, p, p'-oxybisbenzenesulfonyl hydrazide, benzenesulfonylhydrazide, and trihydrazinotriazine, 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, when 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 3. The foaming aid is not particularly limited as long as it promotes 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, as the upper limit of the blending amount of the foaming aid, 200 parts by mass is preferable, and 150 parts by mass is more preferable. 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 3 may unintentionally expand during the production or storage of the insulated wire.

<Physical foaming agent>
The physical foaming agent used as the foaming agent 5 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 used as the main component of the outer shell of the heat-expandable microcapsule is formed of, for example, 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 heat-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 3 may become unnecessarily thick, or the expansion of the heat-sealing layer 3 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 3 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 3, 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 5 and the heat-sealing layer 3 may not be sufficiently expanded, or the heat-sealing layer 3 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 3 may be insufficient. On the contrary, when the expansion coefficient of the heat-expandable microcapsules exceeds the above upper limit, the matrix 5 of the heat-sealing layer 3 cannot follow the heat-expandable microcapsules, and the heat-sealing layer 3 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]
The insulated wire has a step of applying a resin composition for forming an insulating layer on the outer peripheral surface side of the metal conductor 1, a step of drying or curing the applied resin composition for forming an insulating layer, and a step of forming a dried or cured insulating layer. A step of applying a resin composition for forming a heat-sealing layer in which a heat-dissipating filler 6 and a foaming agent 5 are dispersed in a matrix 4 diluted with a solvent on the outer peripheral surface side of the resin composition for use, and a step of volatilizing the solvent to generate heat. It can be produced by a method including a step of drying the resin composition for forming a fused 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 1. As a method of applying the resin composition for forming an insulating layer to the outer peripheral surface side of the metal conductor 1, for example, a coating device including a liquid composition tank for storing the resin composition for forming an insulating layer and a coating die was used. The method 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 1 into the liquid composition tank, and then passes through the coating die to make the liquid composition substantially uniform. It is applied to a thick thickness. Prior to the application of the resin composition for forming an insulating layer, a primer-treated layer may be formed on the outer peripheral surface of the metal conductor 1 by a known method.

(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 the insulating layer 2. Form. 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 the insulating layer 2. 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 1 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.

(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 heat-dissipating filler 6 and the foaming agent 5 are dispersed in a solution obtained by diluting the resin composition constituting the matrix 4 with a solvent to obtain a resin composition for forming a heat-sealing layer. Prepare. As a method of dispersing the heat-dissipating filler 6 and the foaming agent 5 in the resin composition, for example, it can be mixed by 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 2. 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 5, and the heat-sealing layer is formed. Form 3. 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 3, for example, 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-mentioned 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. Further, the insulating layer and the heat-sealing layer may be laminated by yet another method such as spray coating.

The winding using the insulated wire can be applied to an electric device having a high applicable voltage such as a motor used at a high voltage.

[advantage]
In the insulated wire, the thermal conductivity is improved because the foaming agent 5 and the plate-shaped or scaly heat-dissipating filler 6 are dispersed in the matrix 4 in which the heat-sealing layer 3 is mainly composed of synthetic resin. Excellent heat dissipation.

[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. NS.

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 or between the insulating layer and the heat-sealing layer.

(Primer treatment 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. Properties such as flexibility, abrasion resistance, scratch resistance, and work resistance of electric wires can be effectively enhanced.

Further, the resin composition forming the primer-treated layer may contain other resins such as epoxy resin and melamine resin in addition to 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.

As the lower limit of the average thickness of the primer-treated layer, 1 μm is preferable, and 2 μm is more preferable. 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, when the average thickness of the primer-treated layer exceeds the above upper limit, the diameter of the insulated wire may be unnecessarily increased.

Further, when a primer-treated layer is provided between the insulating layer and the heat-sealed layer, a resin composition having high adhesiveness to the insulating layer and the heat-sealed layer is selected based on a known technique.

In addition to forming the coil, the insulated wire can also be used for other purposes such as arranging a plurality of insulated wires in parallel.

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. 9>
By laminating an insulating layer having an average thickness of 40 μm and a heat-sealing layer having an average thickness of 20 μm on a copper wire having a diameter of 1 mm in this order, the insulated wire No. 1-No. 9 was prototyped. The insulating layer and the heat-sealing layer are each coated with the resin composition having the composition shown in Table 1 by 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) in.

[Resin composition for forming an insulating layer]
As the resin composition for forming the insulating layer, a varnish containing polyimide as a main component was used.

[Resin composition for forming a heat-sealed layer]
(Resin component)
As the resin component of the matrix of the resin composition for forming the heat-sealing layer, a phenoxy resin having a glass transition temperature of 130 ° C. (“YP-50” of Nippon Steel & Sumitomo Metal Corporation) was used.

(Foaming agent)
As a foaming agent for the resin composition for forming a heat-sealing layer, a chemical foaming agent azodicarbonamide (“Vinihole AC # 3” manufactured by Eiwa Kasei Co., Ltd.) having a foaming start temperature of 190 ° C. was used.

(Heat-dissipating filler)
Boron nitride (“MBN-010T” by Mitsui Chemicals, Inc.) having a thermal conductivity of 60 (W / m · K) was used as the heat-dissipating filler of the resin composition for forming a heat-sealing layer.

The composition of the resin composition for forming a heat-sealing layer is shown in Table 1.

[Foaming conditions]
The heat-sealing layer was foamed by heating in a constant temperature bath at 210 ° C. for 20 minutes.

[Evaluation of thermal conductivity of heat-sealed layer]
The thermal conductivity of the heat-sealed layer after foaming of each insulated wire was evaluated. Specifically, the thermal conductivity at 25 ° C. was measured by measuring the thermal diffusivity, specific heat and density of the heat-sealed layer after foaming. The measurement results are shown in Table 1.

From the results in Table 1 above, the heat-sealed layer contains a scale-like heat-dissipating filler and a foaming agent, and the content of the heat-dissipating filler with respect to the phenoxy resin is 10% by volume or more and 60% by volume or less. .. 1-No. In No. 6, the thermal conductivity of the heat-sealed layer was excellent.
On the other hand, the insulated wire No. 1 in which the heat-sealing layer contains only one of the heat-dissipating filler and the foaming agent. 7 to No. No. 8 and the insulated wire No. 8 in which the content of the heat-dissipating filler in the heat-sealing layer with respect to the phenoxy resin is less than 10% by volume. For No. 9, the thermal conductivity of the heat-sealed layer after foaming was inferior.
As described above, the insulated wire has a plate-shaped or scaly heat-dissipating filler and a foaming agent in a matrix in which the heat-sealing layer contains a synthetic resin as a main component, and the heat-dissipating filler is used for the synthetic resin. It was shown that when the content was 10% by volume or more and 60% by volume or less, the thermal conductivity was improved and the heat dissipation was excellent.

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 3 Heat fusion layer 4 Matrix 5 Foaming agent 6 Heat dissipation filler 10 Insulated wire

Claims (5)

An insulated wire having a linear metal conductor, an insulating layer laminated on the outer peripheral surface side of the metal conductor, and a heat-sealing layer laminated on the outer peripheral surface side and the outermost side of the insulating layer and expanded by heating. There,
The heat-sealing layer
A matrix whose main component is synthetic resin,
Plate-shaped or scaly heat-dissipating filler dispersed in the above matrix,
Has a foaming agent dispersed in the above matrix
The content of the heat-dissipating filler with respect to the synthetic resin is 10% by volume or more and 60% by volume or less.
The heat dissipation filler has an average particle diameter is not less 10μm or 30μm or less, and the average thickness of Ri der least 5μm below 0.1 [mu] m,
The above foaming agent is an organic foaming agent,
The content of the foaming agent with respect to 100 parts by mass of the synthetic resin is 3 parts by mass or more and 30 parts by mass or less.
The expansion coefficient of the heat-sealed layer that expands due to the above heating is 1.3 times or more and 3 times or less.
The heat sealable layer insulated wire porosity Ru der 10% to 80% of the post-heating. The insulated wire according to claim 1, wherein the aspect ratio obtained by dividing the average particle size of the heat-dissipating filler by the average thickness is 10 or more and 200 or less. The insulated wire according to claim 1 or 2, further comprising a primary treatment layer between the metal conductor and the insulating layer, and between the insulating layer and the heat-sealing layer. The insulated wire according to claim 1, claim 2 or claim 3 , wherein the heat-dissipating filler has a thermal conductivity of 20 W / m · K or more at 25 ° C. The insulated wire according to any one of claims 1 to 4 , which is used as a winding.

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