JP7397876B2 - Insulating sheet, stator and stator manufacturing method - Google Patents

Description

The present disclosure relates to an insulating sheet, a stator including the insulating sheet, and a method for manufacturing the stator.

Conventionally, a stator of an electric motor includes a stator core formed by laminating a plurality of steel plates, and a coil formed by winding an electric wire around the stator core on which insulating paper or insulating film is arranged. In such stators, it is common practice to impregnate the coils with liquid varnish and then heat and harden the varnish to secure the coils and ensure electrical insulation between the stator core and the coils. It is being said.

However, using liquid varnish requires a multi-step and long manufacturing process such as preheating the varnish, impregnating the coil with the varnish, and heating and curing the varnish, as well as requiring large-scale manufacturing equipment. be.

Therefore, as a technique for solving such problems, a technique has been developed in which a sheet-like varnish is provided between the stator core and the coils, as disclosed in Patent Document 1. By placing a sheet of varnish between the stator core and the coil and heating it, the sheet of varnish melts and allows the electric wires to be fixed to the varnish, which is useful when electrically insulating between the stator core and the coil. Effects such as improved performance and reduced stator manufacturing time can be achieved. Further, Patent Document 1 discloses a technique in which heat generated from a coil is easily transmitted to a stator core by laminating a thermosetting resin having high thermal conductivity on an insulating paper or an insulating film.

Japanese Patent Application Publication No. 2003-284277

However, in the technique disclosed in Patent Document 1, the insulating paper and the insulating film impede heat conduction, so there is still room for improvement in heat dissipation from the coil to the stator core.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain an insulating sheet that can improve heat dissipation from a coil to a stator core than before.

In order to solve the above problems and achieve the objects, an insulating sheet according to the present disclosure is provided between a stator core and a coil of a stator including a stator core and a coil formed by winding electric wires in multiple layers around the stator core. an insulating sheet laminated on the surface of the stator core and containing a thermosetting resin and a particulate thermally conductive filler with an average particle size of 40 μm or less; a voltage-withstanding layer containing a thermosetting resin and a plate-shaped filler, which is laminated on a surface facing oppositely to the stator core; A thermally conductive filler that contains only a thermosetting resin or has an average particle size of 1 μm or less and smaller than the width of the gap between the wires, and a thermally conductive filler that has a particle size of 40 μm or more and larger than the width of the gap between the wires. and a fixing layer containing at least one of them and a thermosetting resin. The fluidity of the thermosetting resin of the heat conductive layer and the thermosetting resin of the fixing layer during the heat treatment of the insulating sheet is higher than the fluidity of the thermosetting resin of the voltage-withstanding layer during the heat treatment of the insulating sheet. The thermosetting resin of the heat conductive layer and the thermosetting resin of the fixed layer during the heat treatment of the insulating sheet are liquid resins or resins with a melt viscosity of 1 Pa·s or less. The thermosetting resin of the voltage-withstanding layer during the heat treatment of the insulating sheet is a solid resin.

According to the present disclosure, there is an effect that heat dissipation from the coil to the stator core can be improved more than before.

A cross-sectional view of the electric motor according to Embodiment 1 taken along the central axis. FIG. 2 is a cross-sectional view of the electric motor according to Embodiment 1 taken in a direction perpendicular to the central axis, and is a partially enlarged cross-sectional view showing the stator. A cross-sectional view schematically showing an insulating sheet, a stator core, and a coil according to Embodiment 1. A cross-sectional view schematically showing an insulating sheet, a stator core, and a coil according to a second embodiment. Cross-sectional view schematically showing an insulating sheet, a stator core, and a coil according to Modification 1 of Embodiment 2 A cross-sectional view schematically showing an insulating sheet, a stator core, and a coil according to a second modification of the second embodiment.

Below, an insulating sheet, a stator, and a method for manufacturing the stator according to an embodiment will be described in detail based on the drawings.

Embodiment 1.
FIG. 1 is a cross-sectional view of the electric motor 5 according to the first embodiment taken along the central axis C. The electric motor 5 includes a stator 6, a rotor 7, a shaft 8, a frame 9, and two brackets 10. The stator 6 is formed into a cylindrical shape having a central axis C. Hereinafter, when explaining the directions of each component of the electric motor 5, the direction parallel to the central axis C will be referred to as the axial direction, the direction orthogonal to the central axis C will be referred to as the radial direction, and the direction of rotation around the central axis C will be referred to as the circumferential direction. do.

The rotor 7 is arranged inside the stator 6. A gap is provided between the stator 6 and the rotor 7 over the entire circumference in the circumferential direction. A shaft 8 is connected to the center of the rotor 7. The shaft 8 and the central axis C of the stator 6 are coaxially provided. The rotor 7 is rotatable about a central axis C as a rotation axis. Frame 9 constitutes the outer shell of electric motor 5 and accommodates stator 6 and rotor 7. The frame 9 is formed into a cylindrical shape with openings at both ends along the axial direction. One bracket 10 is arranged so as to close an opening at one end of the frame 9 along the axial direction. The other bracket 10 is arranged so as to close the opening at the other end of the frame 9 in the axial direction. One end of the shaft 8 along the axial direction projects to the outside of the frame 9 through a hole 10a formed in one bracket 10.

The stator 6 includes a stator core 11 formed by laminating a plurality of electromagnetic steel plates, and a coil 15 formed by winding an electric wire 16 around the stator core 11. FIG. 2 is a cross-sectional view of the electric motor 5 according to the first embodiment taken in a direction perpendicular to the central axis C, and is a partially enlarged cross-sectional view showing the stator 6. As shown in FIG. The stator core 11 includes a cylindrical core back 12 made of a magnetic material and a plurality of teeth 13 that protrude radially inward from the inner peripheral surface of the core back 12. A slot 14 is formed between adjacent teeth 13. An insulating sheet 1 is provided within the slot 14. The insulating sheet 1 covers the surface of the core back 12 facing the slot 14 and the surface of the teeth 13 facing the slot 14. An electric wire 16 is wound around each of the plurality of teeth 13 via an insulating sheet 1 to form a coil 15. Although not shown in the drawings, irregularities are formed on the surface of the stator core 11 due to burrs of the electromagnetic steel sheets, misalignment of lamination, and the like. Further, due to the circular shape of the electric wires 16 and the misalignment of the electric wires 16, a gap G is formed between adjacent electric wires 16. Note that the stator 6 is not limited to the illustrated example, and may be appropriately selected from known stators.

FIG. 3 is a cross-sectional view schematically showing the insulating sheet 1, stator core 11, and coil 15 according to the first embodiment. Insulating sheet 1 is an insulating member provided between stator core 11 and coil 15. The insulating sheet 1 includes a thermally conductive layer 2, a voltage withstanding layer 3, and a fixing layer 4. The insulating sheet 1 has a three-layer structure.

Thermal conductive layer 2 is laminated on the surface of stator core 11 and contains particulate thermally conductive filler 22 having an average particle size of 40 μm or less. Since the thermally conductive layer 2 contains particulate thermally conductive filler 22 with an average particle size of 40 μm or less, it fills in the unevenness of the stator core 11 and increases the thermal conductivity from the coil 15 to the stator core 11. It has the effect of increasing the adhesion of the material. The thermally conductive layer 2 is a thermosetting resin composition containing a thermosetting resin 21 and a thermally conductive filler 22.

As the thermosetting resin 21 of the heat conductive layer 2, for example, a thermosetting resin that forms a three-dimensional network when heated is used. Examples of the thermosetting resin 21 include epoxy resin, phenol resin, melamine resin, urea resin, furan resin, silicone resin, allyl resin, alkyd resin, unsaturated polyester resin, thermosetting resin polyurethane, polyimide resin, and rubber. Can be mentioned. From the viewpoint of facilitating the manufacture of the insulating sheet 1, it is preferable to use an epoxy resin or an unsaturated polyester resin as the thermosetting resin 21. Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, alicyclic aliphatic epoxy resin, glycidyl-aminophenol epoxy resin, epoxy resin containing a naphthalene skeleton, anthracene skeleton, and isocyanuric acid skeleton, and semiconductors. Phenol novolac type epoxy resin for sealing, novolac type epoxy resin such as cresol novolac type epoxy resin, triphenolalkane type epoxy resin such as triphenolmethane type epoxy resin, triphenolpropane type epoxy resin, biphenyl type epoxy resin, phenol Examples include highly heat-resistant resins such as aralkyl epoxy resins, biphenylaralkyl epoxy resins, and heterocyclic epoxy resins. These epoxy resins may be used alone or in combination of two or more.

The thermosetting resin 21 of the heat conductive layer 2 may be a liquid resin with high fluidity, a resin with a low melt viscosity, or , a resin mixed with a low-viscosity reactive diluent is preferable. "Low melt viscosity" means, for example, that the melt viscosity is 1 Pa·s or less. Examples of resins with low melt viscosity include bisphenol A epoxy resins with an epoxy equivalent of 300 or less, bisphenol F epoxy resins with an epoxy equivalent of 200 or less, trifunctional glycidylamine epoxy resins, and unsaturated polyester resins. These resins having low melt viscosity may be used alone, or two or more types may be used in combination.

The thermosetting resin 21 may be a mixture of a highly heat resistant, high viscosity resin mixed with a low viscosity reactive diluent. Examples of the reactive diluent include diallylphthalate, styrene derivatives, and (meth)acrylate derivatives. Examples of the diallyl phthalate type include ortho diallyl phthalate, meta diallyl phthalate, and para diallyl phthalate, which have different allyl attachment positions on the benzene ring. Examples of styrene derivatives include styrene, 1-methyl-2-vinylbenzene, 1-ethyl-2-vinylbenzene, 1-propyl-2-vinylbenzene, 1-methyl-3-vinylbenzene, 1-ethyl-3 -Vinylbenzene, 1-propyl-3-vinylbenzene, 1-ethyl-4-vinylbenzene, 1-propyl-4-vinylbenzene, 1,2-methyl-4-vinylbenzene, 1,3-methyl-4- Vinylbenzene, 1,4-methyl-4-vinylbenzene, 1,2-ethyl-4-vinylbenzene, 1,3-ethyl-4-vinylbenzene, 1,4-ethyl-4-vinylbenzene, 1,2 -Methyl-5-vinylbenzene, 1,3-methyl-5-vinylbenzene, 1,4-methyl-5-vinylbenzene, 1,2-ethyl-5-vinylbenzene, 1,3-ethyl-5-vinyl Benzene, 1,4-ethyl-5-vinylbenzene, 1,2-methyl-6-vinylbenzene, 1,3-methyl-6-vinylbenzene, 1,4-methyl-6-vinylbenzene, 1,2- Ethyl-6-vinylbenzene, 1,3-ethyl-6-vinylbenzene, 1,4-ethyl-6-vinylbenzene, ortho-t-butylstyrene, m-t-butylstyrene, pt-butylstyrene Can be mentioned. Examples of (meth)acrylate derivatives include 2-hydroxyethyl (meth)acrylate, carbitol (meth)acrylate, isobornyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-(meth)acryloyloxyethyl- 2-Hydroxypropyl phthalate, ethylene glycol (meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate meth)acrylate, bisphenoxyethanolfluorene diacrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tri((meth)acryloyloxyethyl)phosphate, pentaerythritol tetra(meth)acrylate, dipenta Examples include erythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate. These polymerizable unsaturated monomers as reactive diluents may be used alone, or two or more types may be used in combination. Among these polymerizable unsaturated monomers, it is preferable to use diallyl phthalate, and it is particularly preferable to use meta-diallyl phthalate. Since the diallylphthalate-based polymerizable unsaturated monomer exhibits relatively high heat resistance even when used alone, it is possible to obtain a thermosetting resin composition with higher heat resistance than when it contains other reactive diluents. . Moreover, it is preferable that the polymerizable unsaturated monomer has a viscosity of 50 mPa·s or less at room temperature. "Room temperature" means 25°C. If a polymerizable unsaturated monomer with a viscosity of more than 50 mPa・s at room temperature is used, the temperature of the thermosetting resin 21 that has a viscosity that can be impregnated will become high, and as a result, the time it takes for the thermosetting resin 21 to start curing will become shorter. As the pot life becomes shorter, there is a risk that workability will decrease.

As the polymerization initiator for the polymerizable unsaturated monomer, one having a 10-hour half-life temperature of 100° C. or higher is preferable. Examples of polymerization initiators for polymerizable unsaturated monomers include dicumyl peroxide, 2,5-dimethyl-2,5(dibenzoylperoxy)hexane, di-t-butyl peroxide, and 2,5-dimethyl- 2,5-di(t-butylperoxy)hexyne-3, di-t-amylperoxide, 2,2-di(t-butylperoxy)butane, n-butyl-4,4-di(t- butylperoxy) parerate, ethyl 3,3-di(t-butylperoxy)butyrate, 1,1,3,3-tetramethylbutyl hydroperoxide, t-butyl hydroperoxide, t-amyl hydroperoxide. Can be mentioned. The upper limit of the 10-hour half-life temperature of the polymerization initiator of the polymerizable unsaturated monomer is not particularly limited, but is usually 170° C. or lower.

A curing agent is added to the thermosetting resin composition in order to harden the thermosetting resin 21. The type of curing agent is not particularly limited as long as it can chemically react with the thermosetting resin 21 and harden the thermosetting resin 21, and may be appropriately selected from known curing agents. When an epoxy resin is used as the thermosetting resin 21, examples of the curing agent for the epoxy resin include amine curing agents such as ethylene diamine and polyamide amine, phthalic anhydride, hexahydrophthalic anhydride, and 4-methylhexahydro. Acid anhydride curing agents such as phthalic anhydride, tetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, tetrabromo phthalic anhydride, methyl nadic anhydride, dodecenyl succinic anhydride, pyrolimetic anhydride, novolak type phenolic resin, cresol Examples include phenolic curing agents such as novolac type phenolic resins. The amount of the curing agent may be adjusted appropriately depending on the type of thermosetting resin 21 and the type of curing agent used, and is 0.1 parts by mass or more and 200 parts by mass or less based on 100 parts by mass of thermosetting resin 21. It is common to do so.

Further, a curing accelerator is added to the thermosetting resin composition in order to accelerate curing of the thermosetting resin 21. The type of curing accelerator is not particularly limited as long as it can promote curing of the thermosetting resin 21, and may be appropriately selected from known curing accelerators. When an epoxy resin is used as the thermosetting resin 21, examples of the curing accelerator include tertiary amines such as benzyldimethylamine, imidazoles such as 2-ethyl-4-methylimidazole, and zinc octylate. Examples include organic metals.

Inorganic particles may be used in the thermally conductive filler 22 of the thermally conductive layer 2 from the viewpoint of improving thermal conductivity and electrical insulation, or achieving a balance between thermal conductivity and electrical insulation. preferable. Examples of inorganic particles include fused silica (SiO ₂ ), crystalline silica (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum hydroxide (Al(OH) ₃ ), magnesium oxide (MgO), and magnesium hydroxide. (Mg(OH) ₂ ), boron nitride (BN), aluminum nitride (AlN), and silicon carbide (SiC). These inorganic particles may be used alone, or two or more types may be used in combination. Further, secondary agglomerated particles of these inorganic particles may be used as the thermally conductive filler 22. The blending amounts of inorganic particles and secondary agglomerated particles are not particularly limited as long as they do not impede the effects of the present disclosure, and may be adjusted as appropriate. The average particle size of the thermally conductive filler 22 is 40 μm or less, preferably 0.5 μm or more and 30 μm or less. When the average particle size of the thermally conductive filler 22 is 0.5 μm or more and 30 μm or less, the thermal conductivity of the thermally conductive layer 2 can be improved while ensuring the electrical insulation of the thermally conductive layer 2.

From the viewpoint of improving the adhesive force at the interface between the thermosetting resin 21 and the thermally conductive filler 22, the thermally conductive layer 2 may contain a coupling agent. Examples of coupling agents include γ-glycidoxypropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Methoxysilane is mentioned. These coupling agents may be used alone or in combination of two or more. The amount of the coupling agent may be adjusted as appropriate depending on the type of the thermosetting resin 21 and coupling agent used, and is 0.01% by mass or more and 1% by mass or less based on 100 parts by mass of the thermosetting resin 21. It is common to do so.

The voltage withstanding layer 3 shown in FIG. 3 is laminated on the surface of the heat conductive layer 2 facing away from the stator core 11, and contains a plate-shaped filler 32. Since the voltage-withstanding layer 3 contains the plate-shaped filler 32, it exhibits the effect of improving the electrical insulation properties of the insulating sheet 1. The voltage-withstanding layer 3 is a thermosetting resin composition containing a thermosetting resin 31 and a plate-shaped filler 32.

The thermosetting resin 31 of the voltage-withstanding layer 3 can be a solid resin with low fluidity, a resin with high melt viscosity, or a combination of a resin with high melt viscosity and a liquid resin during the heat treatment of the insulating sheet 1 to be described later. Preferably, it is a mixture of. "High melt viscosity" means, for example, that the melt viscosity is 10 Pa·s or more. Examples of the thermosetting resin 31 of the withstand voltage layer 3 include bisphenol A epoxy resin with an epoxy equivalent of 450 or more, bisphenol F epoxy resin with an epoxy equivalent of 800 or more, phenol novolac epoxy resin, cresol novolak epoxy resin, glycidyl. - Aminophenol epoxy resin, epoxy resin containing naphthalene skeleton, anthracene skeleton, isocyanuric acid skeleton, triphenolalkane epoxy resin, biphenyl epoxy resin, phenol aralkyl epoxy resin, biphenylaralkyl epoxy resin, heterocyclic epoxy Examples include resin.

An example of mixing a resin with a high melt viscosity and a liquid resin is when a phenoxy resin with a molecular weight of 50,000 is blended with a liquid bisphenol A type epoxy resin with an epoxy equivalent of 180. This reduces the fluidity of the liquid bisphenol A epoxy resin. Examples of resins with high melt viscosity include phenoxy resins with a molecular weight of 30,000 or more, polyethylene, polypropylene, poly-4-methylpentene-1, ionomers, polystyrene, AS resins (acrylonitrile-styrene copolymer synthetic resins), ABS resins ( Acrylonitrile-butadiene-styrene copolymer synthetic resin), polyvinyl chloride, polyvinylidene chloride, methacrylic resin, polyvinyl alcohol, EVA resin (ethylene-vinyl acetate copolymer synthetic resin), polycarbonate, various nylons, various aromatic or aliphatic Polyester, thermoplastic polyurethane, cellulose plastic, thermoplastic elastomer, polyarylate resin, polyethylene terephthalate, polybutylene terephthalate, polyimide, polyamideimide, polyetherimide, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenyl ether, polybenzimidazole , aramid, and polyparaphenylenebenzobisoxazole. These resins with high melt viscosity may be used alone, or two or more types may be used in combination.

Examples of the plate-like filler 32 of the voltage withstanding layer 3 include mica, alumina, boron nitride, magnesium carbonate, talc, and layered silicate. These plate-shaped fillers 32 may be used alone, or two or more types may be used in combination. The blending amount of the plate-shaped filler 32 is not particularly limited as long as it does not impede the effects of the present disclosure, and may be adjusted as appropriate. It is preferable that the average particle size of the plate-shaped filler 32 is 10 μm or more. When the average particle size of the plate-shaped filler 32 is 10 μm or more, the plate-shaped filler 32 is easily oriented in the horizontal direction, and electrical insulation in the thickness direction of the insulating sheet 1 can be ensured. That is, since the plate-shaped filler 32 is easily oriented so that the long axis direction of the plate-shaped filler 32 is perpendicular to the thickness direction of the insulating sheet 1, electrical insulation in the thickness direction of the insulating sheet 1 can be ensured. On the other hand, if the average particle size of the plate-shaped filler 32 is less than 10 μm, the plate-shaped filler 32 is likely to be oriented in various directions, and the electrical insulation properties of the insulating sheet 1 in the thickness direction may be reduced.

Further, the voltage withstanding layer 3 may contain nanoparticles having an average particle size of 300 nm or less. Preferably, electrically insulating inorganic particles are used as the nanoparticles. Examples of the electrically insulating inorganic particles include silica, boron nitride, alumina, magnesia, aluminum nitride, magnesium hydroxide, magnesium oxide, calcium carbonate, magnesium carbonate, and titanium oxide. If the average particle size of the nanoparticles is larger than 300 nm, the horizontal orientation of the plate-shaped filler 32 may be hindered, and the electrical insulation properties of the insulating sheet 1 in the thickness direction may deteriorate.

From the viewpoint of improving the adhesive force at the interface between the thermosetting resin 31 and the plate-shaped filler 32, the voltage-withstanding layer 3 may contain a coupling agent. Examples of coupling agents include γ-glycidoxypropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Methoxysilane is mentioned. These coupling agents may be used alone or in combination of two or more. The amount of the coupling agent may be adjusted as appropriate depending on the type of the thermosetting resin 31 and coupling agent used, and is 0.01% by mass or more and 1% by mass or less based on 100 parts by mass of the thermosetting resin 31. It is common to do so.

The fixing layer 4 shown in FIG. 3 is a layer that is laminated on the surface of the voltage withstanding layer 3 facing away from the stator core 11, and to which the electric wire 16 is fixed. The fixing layer 4 has the effect of filling the gap G between adjacent electric wires 16, increasing the thermal conductivity from the coil 15 to the stator core 11, and increasing the adhesion to the coil 15. In this embodiment, the fixed layer 4 does not contain a thermally conductive filler. Fixed layer 4 contains only thermosetting resin 41 in this embodiment.

The thermosetting resin 41 of the fixing layer 4 is a liquid resin with high fluidity and low melt viscosity, from the viewpoint of making it easier to penetrate into the gap G between adjacent electric wires 16 during the heat treatment of the insulating sheet 1, which will be described later. It is preferable to use a resin or a resin mixed with a low-viscosity reactive diluent. Examples of resins with low melt viscosity include bisphenol A epoxy resins with an epoxy equivalent of 300 or less, bisphenol F epoxy resins with an epoxy equivalent of 200 or less, trifunctional glycidylamine epoxy resins, and unsaturated polyester resins. These resins having low melt viscosity may be used alone, or two or more types may be used in combination. The thermosetting resin 41 may be a mixture of a highly heat resistant, high viscosity resin mixed with a low viscosity reactive diluent. As the reactive diluent and the polymerization initiator for the polymerizable unsaturated monomer, the same reactive diluent and polymerization initiator for the polymerizable unsaturated monomer as those used in the thermally conductive layer 2 described above are used. The fluidity of the thermosetting resin 21 of the heat conductive layer 2 and the thermosetting resin 41 of the fixed layer 4 during the heat treatment of the insulating sheet 1 is the same as that of the thermosetting resin of the voltage-withstanding layer 3 during the heat treatment of the insulating sheet 1. The liquidity is higher than that of 31.

Next, with reference to FIG. 3, a method for manufacturing the stator 6 according to this embodiment will be described. The method for manufacturing the stator 6 includes a forming step, a laminating step, an arrangement step, and a fixing step.

The formation process is a process of forming the voltage withstanding layer 3, the heat conductive layer 2, and the fixed layer 4. The forming process includes a thermally conductive layer forming process, a withstand voltage layer forming process, and a fixed layer forming process.

In the thermally conductive layer forming step, an amount of thermosetting resin 21 necessary for forming the thermally conductive layer 2 and an amount of curing agent necessary for curing the thermosetting resin 21 are mixed. Subsequently, a solvent is added to this mixture and mixed, and then a particulate thermally conductive filler 22 is further added and premixed. By kneading this premix using a roll, kneader, high-speed stirring device, etc., a thermosetting resin composition for a heat conductive layer is obtained. The solvent is not particularly limited, and may be appropriately selected from known solvents. Examples of the solvent include toluene and methyl ethyl ketone. The blending amount of the solvent is not particularly limited as long as it can be premixed, and is generally 30% by mass or more and 85% by mass or less in the thermosetting resin composition. Note that if the viscosity of the thermosetting resin composition is low, it is not necessary to add a solvent. Moreover, when a coupling agent is blended, the coupling agent may be added to the premix before the kneading step.

Next, a thermosetting resin composition for a heat conductive layer is applied to the base film that has been subjected to a mold release treatment. Examples of the method for applying the thermosetting resin composition for the heat conductive layer include a doctor blade method. Subsequently, the sheet-like heat conductive layer 2 is obtained by drying this coated material and volatilizing the solvent in the coated material. In addition, when drying the coated article, the coated article may be heated to 60° C. or higher and 150° C. or lower to promote volatilization of the solvent in the coated article, if necessary. Furthermore, in order to remove voids contained in the sheet-like heat conductive layer 2, the heat conductive layer 2 may be subjected to a press treatment after drying the coated material.

In the voltage-withstanding layer forming step, an amount of thermosetting resin 31 necessary for forming the voltage-withstanding layer 3 and an amount of curing agent necessary for curing the thermosetting resin 31 are mixed. Subsequently, a solvent is added to this mixture and mixed, and then a plate-shaped filler 32 is further added and premixed. By kneading this premix using a roll, kneader, high-speed stirring device, etc., a thermosetting resin composition for a voltage-withstanding layer is obtained. The type and amount of the solvent are the same as those for the heat conductive layer 2 described above. In addition, as with the thermally conductive layer 2 described above, if the viscosity of the thermosetting resin composition is low, it is not necessary to add a solvent, and if a coupling agent is added, it may be necessary to add a coupling agent before the kneading process. A coupling agent may be added to the premix.

Next, a thermosetting resin composition for a voltage-resistant layer is applied to the base film that has been subjected to a mold release treatment. Examples of the method for applying the thermosetting resin composition for the voltage-withstanding layer include a doctor blade method. Subsequently, this coated product is dried and the solvent in the coated product is evaporated to obtain a sheet-like voltage-resistant layer 3. In addition, when drying the coated article, the coated article may be heated to 60° C. or higher and 150° C. or lower to promote volatilization of the solvent in the coated article, if necessary. Further, in order to orient the plate-shaped filler 32 in the horizontal direction, the voltage-withstanding layer 3 may be subjected to a press treatment after the coated material is dried.

In the fixed layer forming step, an amount of thermosetting resin 41 necessary for forming the fixed layer 4 and a curing agent required for curing the thermosetting resin 41 are mixed. Subsequently, a solvent is added to this mixture and premixed. By kneading this premix using a roll, kneader, high-speed stirring device, etc., a thermosetting resin composition for the fixed layer is obtained. The type and amount of the solvent are the same as those for the heat conductive layer 2 described above. In addition, as with the thermally conductive layer 2 described above, if the viscosity of the thermosetting resin composition is low, it is not necessary to add a solvent, and if a coupling agent is added, it may be necessary to add a coupling agent before the kneading process. A coupling agent may be added to the premix.

Next, a thermosetting resin composition for the fixing layer is applied to the base film that has been subjected to a mold release treatment. An example of a method for applying the thermosetting resin composition for the fixed layer is a doctor blade method. Subsequently, this coated material is dried and the solvent in the coated material is evaporated, thereby obtaining a sheet-like fixed layer 4. In addition, when drying the coated article, the coated article may be heated to 60° C. or higher and 150° C. or lower to promote volatilization of the solvent in the coated article, if necessary. Further, in order to remove voids contained in the sheet-like adhesive layer 4, the adhesive layer 4 may be subjected to a press treatment after drying of the coated material.

In the fixed layer forming step, a reinforcing base material may be added to the fixed layer 4 in order to reinforce the insulating sheet 1. Examples of the reinforcing base material include fiber base materials such as glass cloth and nonwoven fabric, polyester film, and nylon. When glass cloth is used as the reinforcing base material, the strength of the insulating sheet 1 can be changed by changing the thickness of the threads of the glass cloth or increasing or decreasing the number of warp threads of the glass cloth. Examples of the nonwoven fabric include glass fiber nonwoven fabric and polyester fiber nonwoven fabric. The thickness of the reinforcing base material may be appropriately set according to the thickness of the insulating sheet 1 to be manufactured, and is preferably from 0.01 mm to 0.2 mm, for example.

The lamination process is a process in which the thermally conductive layer 2, the voltage withstanding layer 3, and the fixed layer 4 formed in the formation process are stacked on top of each other. In the lamination step, the thermally conductive layer 2, the voltage-resistant layer 3, and the fixing layer 4, which have been peeled off from the base film, are laminated. In the lamination process, the thermally conductive layer 2, the voltage withstanding layer 3, and the fixed layer 4 are laminated in this order. In the lamination process, the thermally conductive layer 2, the voltage-resistant layer 3, and the fixed layer 4 are heated and pressurized using a vacuum laminating device, a press device, or the like. The insulating sheet 1 may be formed by integrating the two. Alternatively, the insulating sheet 1 may be formed by directly applying the thermally conductive layer 2 and the fixing layer 4 on the upper and lower sides of the voltage-resistant layer 3. Through the lamination process, a three-layer insulating sheet 1 is obtained.

The arrangement step is a step of arranging the insulating sheet 1 and the coil 15 in the slot 14 provided in the stator core 11 shown in FIG. In the arrangement step, the insulating sheet 1 is arranged on the surface of the core back 12 facing the slot 14 and the surface of the teeth 13 facing the slot 14. Subsequently, the electric wire 16 is wound around each of the plurality of teeth 13 via the insulating sheet 1, thereby forming the coil 15. Thereby, the insulating sheet 1 is arranged between the stator core 11 and the coil 15.

The fixing process is a process of heating the insulating sheet 1 shown in FIG. 3 to fix the insulating sheet 1 to the stator core 11 and the coil 15 after the arrangement process. By heating and curing the insulating sheet 1, the insulating sheet 1 is fixed to the stator core 11 and the coil 15. Thereby, the stator 6 provided with the insulating sheet 1 is obtained. Note that the heating temperature of the insulating sheet 1 is, for example, 150°C.

Next, the effects of the insulating sheet 1 and the stator 6 according to this embodiment will be explained.

In this embodiment, as shown in FIG. 3, the insulating sheet 1 is laminated on the surface of the stator core 11 and contains a thermosetting resin 21 and a particulate thermally conductive filler 22 with an average particle size of 40 μm or less. A thermally conductive layer 2 is provided. Thereby, the thermal conductivity from the coil 15 to the stator core 11 can be increased, and the adhesion between the insulating sheet 1 and the stator core 11 can be improved. In particular, in this embodiment, the fluidity of the thermosetting resin 21 of the heat conductive layer 2 during the heat treatment of the insulating sheet 1 is the same as that of the thermosetting resin 31 of the voltage-withstanding layer 3 during the heat treatment of the insulating sheet 1. Since the fluidity is higher than that of the heat conductive layer 2, the heat conductive layer 2 easily penetrates into the irregularities formed on the surface of the stator core 11. Therefore, the unevenness formed on the surface of the stator core 11 can be filled with the heat conductive layer 2, and the heat conductivity from the coil 15 to the stator core 11 and the adhesion between the insulating sheet 1 and the stator core 11 can be further improved. .

Furthermore, in this embodiment, the insulating sheet 1 includes a voltage-withstanding layer 3 laminated on the surface of the heat conductive layer 2 facing away from the stator core 11 and containing a thermosetting resin 31 and a plate-shaped filler 32. . Thereby, the electrical insulation properties of the insulating sheet 1 can be improved. In particular, in this embodiment, when the electric wires 16 are wound around the stator core 11, the plate-shaped filler 32 prevents the electric wires 16 from digging into the insulating sheet 1, thereby suppressing the reduction in the thickness of the insulating sheet 1, The electrical insulation of the sheet 1 can be ensured.

Furthermore, in this embodiment, the insulating sheet 1 is laminated on the surface of the voltage-withstanding layer 3 facing away from the stator core 11 to which the electric wire 16 can be fixed, and is a fixing layer containing only the thermosetting resin 41. 4. Thereby, the thermal conductivity from the coil 15 to the stator core 11 can be improved, and the adhesion between the insulating sheet 1 and the coil 15 can be improved. In particular, in this embodiment, the fluidity of the thermosetting resin 41 of the fixed layer 4 during the heat treatment of the insulating sheet 1 is the same as the fluidity of the thermosetting resin 31 of the voltage-withstanding layer 3 during the heat treatment of the insulating sheet 1. Since the bonding layer 4 is higher than the bond strength, the fixed layer 4 easily penetrates into the gap G between adjacent electric wires 16 in the coil 15. Therefore, the gap G between adjacent electric wires 16 can be filled with the adhesion layer 4, and the thermal conductivity from the coil 15 to the stator core 11 and the adhesion between the insulating sheet 1 and the coil 15 can be further improved.

Therefore, in this embodiment, the electrical insulation between stator core 11 and coil 15 can be increased, and the thermal conductivity from coil 15 to stator core 11 can be increased to transfer heat generated from coil 15 to stator core 11. It can efficiently transmit and dissipate heat. Moreover, the adhesion between the insulating sheet 1 and the stator core 11 and the adhesion between the insulating sheet 1 and the coil 15 can be improved.

In this embodiment, by disposing the insulating sheet 1 between the stator core 11 and the coil 15 and heating it, the insulating sheet 1 is melted and the electric wires 16 can be fixed to the insulating sheet 1. Therefore, it is possible to achieve effects such as improved workability when electrically insulating between the stator core 11 and the coil 15 and shorten the manufacturing time of the stator 6, and also eliminate the need for large-scale manufacturing equipment. Therefore, the productivity of the stator 6 can be increased compared to the case where liquid varnish is used.

In this embodiment, the insulating sheet 1 of the present disclosure is used for the stator 6 of the electric motor 5, but the insulating sheet 1 of the present disclosure may be used for the stator of a generator, a compressor, or the like. Furthermore, the fixed layer 4 only needs to contain at least the thermosetting resin 41.

Embodiment 2.
FIG. 4 is a cross-sectional view schematically showing an insulating sheet 1A, a stator core 11, and a coil 15 according to the second embodiment. The second embodiment differs from the first embodiment described above in that the fixed layer 4A contains a thermally conductive filler 42. In the second embodiment, the same parts as those in the first embodiment described above are given the same reference numerals and the description thereof will be omitted.

The fixed layer 4A contains a thermosetting resin 41 and a particulate thermally conductive filler 42. The thermally conductive filler 42 of the fixed layer 4A has a particle size distribution different from that of the thermally conductive filler 22 of the thermally conductive layer 2, considering the permeability of the thermosetting resin 41 into the gap G between adjacent electric wires 16. is preferable, but it may have the same particle size distribution as the thermally conductive filler 22 of the thermally conductive layer 2. In the thermally conductive filler 42 of the fixed layer 4A, inorganic particles are preferably used from the viewpoint of improving thermal conductivity and electrical insulation, and achieving a balance between thermal conductivity and electrical insulation. . Examples of the inorganic particles include fused silica, crystalline silica, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, boron nitride, aluminum nitride, and silicon carbide. These inorganic particles may be used alone, or two or more types may be used in combination. Further, secondary agglomerated particles of these inorganic particles may be contained in the fixed layer 4A. The blending amounts of inorganic particles and secondary agglomerated particles are not particularly limited as long as they do not impede the effects of the present disclosure, and may be adjusted as appropriate.

The average particle size of the thermally conductive filler 42 of the fixed layer 4A is 1 μm or less. The average particle size of the thermally conductive filler 42 is smaller than the width W of the gap G. According to this embodiment, since the average particle size of the thermally conductive filler 42 is 1 μm or less, the thermally conductive filler 42 is applied to the gap G between adjacent electric wires 16 together with the thermosetting resin 41 during the arrangement process. It becomes easier to penetrate. By permeating the thermally conductive filler 42 into the gap G between adjacent electric wires 16, the insulating sheet 1A and the coil 15 can be reliably fixed. Note that in order to obtain the fixed layer 4A containing the thermally conductive filler 42, in the fixed layer forming step, after adding a solvent to the mixture of the thermosetting resin 41 and the curing agent, the particulate thermally conductive filler is added. 42 is further added and premixed. By kneading this premix using a roll, kneader, high-speed stirring device, etc., a thermosetting resin composition for the fixed layer containing the thermally conductive filler 42 is obtained. Then, this thermosetting resin composition for the fixing layer is applied to a base film that has been subjected to mold release treatment, and the coating is dried to evaporate the solvent in the coating to form a sheet-like fixation layer. Layer 4A is obtained.

Next, with reference to FIG. 5, an insulating sheet 1B according to a first modification of the second embodiment will be described. FIG. 5 is a cross-sectional view schematically showing an insulating sheet 1B, a stator core 11, and a coil 15 according to a first modification of the second embodiment. The insulating sheet 1B according to the first modification is different from the insulating sheet 1A of the second embodiment described above in the particle size distribution of the thermally conductive filler 43 of the fixed layer 4B. In Modification 1, parts that overlap with the insulating sheet 1A of Embodiment 2 described above are given the same reference numerals and explanations are omitted.

The particle size of the thermally conductive filler 43 of the fixed layer 4B is 40 μm or more. The particle size of the thermally conductive filler 43 is larger than the width W of the gap G between adjacent electric wires 16 . According to this embodiment, since the particle size of the thermally conductive filler 43 is 40 μm or more, it becomes difficult for the thermally conductive filler 43 to penetrate into the gap G between the adjacent electric wires 16 during the placement process, and the fixed layer 4B Of these, only the thermosetting resin 41 remains in the portion located between the stator core 11 and the coil 15 and permeates into the gap G between the adjacent electric wires 16 . By remaining the thermally conductive filler 43 in the portion of the fixed layer 4B located between the stator core 11 and the coil 15, heat dissipation from the stator core 11 to the coil 15 can be improved.

Next, with reference to FIG. 6, an insulating sheet 1C according to a second modification of the second embodiment will be described. FIG. 6 is a cross-sectional view schematically showing an insulating sheet 1C, a stator core 11, and a coil 15 according to a second modification of the second embodiment. The insulating sheet 1C according to the second modification is different from the insulating sheet 1A of the second embodiment described above in the particle size distribution of the thermally conductive filler 42 of the fixed layer 4C. In Modification 2, the same reference numerals are given to the parts that overlap with those of the insulating sheet 1A of Embodiment 2 described above, and the description thereof will be omitted.

The fixed layer 4C contains a thermally conductive filler 42 with an average particle size of 1 μm or less and a thermally conductive filler 43 with a particle size of 40 μm or more. According to this embodiment, since the average particle size of the thermally conductive filler 42 is 1 μm or less, the thermally conductive filler 42 easily penetrates into the gap G between the adjacent electric wires 16 together with the thermosetting resin 41. By permeating the thermally conductive filler 42 into the gap G between adjacent electric wires 16, the insulating sheet 1C and the coil 15 can be reliably fixed. Further, according to the present embodiment, since the particle size of the thermally conductive filler 43 is 40 μm or more, the thermally conductive filler 43 is difficult to penetrate into the gap G between adjacent electric wires 16, and the stator core of the fixed layer 4C is 11 and the coil 15, the thermosetting resin 41 and the thermally conductive filler 42 penetrate into the gap G between the adjacent electric wires 16. By remaining the thermally conductive filler 43 in the portion of the fixed layer 4C located between the stator core 11 and the coil 15, heat dissipation from the stator core 11 to the coil 15 can be improved. That is, in this embodiment, by mixing the thermally conductive filler 42 with an average particle size of 1 μm or less and the thermally conductive filler 43 with a particle size of 40 μm or more in the fixed layer 4C, the insulating sheet 1C and the coil 15 can be bonded. The adhesion of the stator core 11 to the coil 15 can be improved, and the heat dissipation from the stator core 11 to the coil 15 can be improved.

Next, the effects of the present disclosure will be further explained using Examples and Comparative Examples.

(Example 1)
100 parts by mass of bisphenol A epoxy resin ("jER828US" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and alumina particles ("DAM-07" manufactured by Denka Corporation) with an average particle size of 8 μm as a thermally conductive filler were thermoset. The curing resin, thermally conductive filler, and curing catalyst were mixed in an amount of 60% by volume based on the total volume. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. To this mixture, 150 parts by mass of methyl ethyl ketone was added as a solvent and mixed uniformly by stirring. The thermosetting resin composition thus obtained was applied onto a PET (Polyethylene Terephthalate) substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 80°C for 8 minutes. The solvent in the coating was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 80° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like heat conductive layer having a thickness of 100 μm.

Next, 230 parts by mass of methyl ethyl ketone was added as a solvent to 100 parts by mass of bisphenol A epoxy resin (JER1007 manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and the mixture was stirred to uniformly distribute the thermosetting resin in the solvent. It was dissolved in To the resulting mixture, plate-shaped mica particles (manufactured by Okabe Mica Co., Ltd.) with an average particle size of 400 μm were added as a plate-shaped filler at 50% by volume based on the total volume of the thermosetting resin, plate-shaped filler, and curing catalyst. It was blended so that Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 100° C. for 5 minutes. The solvent in the mixture was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 120° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like voltage-resistant layer having a thickness of 150 μm. When this voltage-resistant layer was confirmed using an electron microscope, it was confirmed that the plate-shaped mica particles in the voltage-resistant layer were oriented in the horizontal direction.

Next, 50 parts by mass of methyl ethyl ketone was added as a solvent to 100 parts by mass of bisphenol A epoxy resin (JER1007 manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and the mixture was stirred to uniformly distribute the thermosetting resin in the solvent. It was dissolved in In the resulting mixture, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) as a curing catalyst for the thermosetting resin was blended with 100 parts by mass of bisphenol A epoxy resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 100° C. for 5 minutes. The solvent in the mixture was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 120° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like fixed layer having a thickness of 200 μm. The fixed layer does not contain filler and contains only thermosetting resin.

Next, the thermally conductive layer, the voltage-resistant layer, and the fixing layer that have been peeled off from the PET base material are laminated, and heated at 100°C for 2 minutes using a vacuum laminating device. An insulating sheet in which a voltage layer and a fixed layer were integrated was obtained. The insulating sheet according to Example 1 was obtained by heating and curing the obtained insulating sheet at 160° C. for 2 hours.

(Example 2)
100 parts by mass of an unsaturated polyester resin (Neopol 8026, manufactured by U-Pica Japan) as a thermosetting resin, and alumina particles with an average particle size of 8 μm (DAM-07, manufactured by Denka Corporation) as a thermally conductive filler were thermoset. The total volume of the thermally conductive resin, thermally conductive filler, and reaction initiator was 60% by volume. Furthermore, 3 parts by mass of dicumyl peroxide ("Percyl D" manufactured by NOF Corporation) was blended with 100 parts by mass of the unsaturated polyester resin as a reaction initiator for the thermosetting resin. This mixture was mixed uniformly by stirring. The thermosetting resin composition thus obtained was applied to a sheet-like member in which a voltage-resistant layer and an adhesive layer similar to those in Example 1 were laminated together using a vacuum laminating device so that the thickness was 100 μm. It was applied using the doctor blade method. Then, by heating the thermally conductive layer, voltage-resistant layer, and adhesive layer at 100°C for 2 minutes using a vacuum laminating device, an insulating layer in which the thermally conductive layer, voltage-resistant layer, and adhesive layer are integrated is formed. Got a sheet. The insulating sheet according to Example 2 was obtained by heating and curing the obtained insulating sheet at 160° C. for 2 hours.

(Example 3)
100 parts by mass of bisphenol A type epoxy resin ("jER828US" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and boron nitride aggregate particles with an average particle size of 15 μm ("HP40-J2" manufactured by Mizushima Alloy Co., Ltd.) as a thermally conductive filler. ) was blended in an amount of 50% by volume based on the total volume of the thermosetting resin, thermally conductive filler, and curing catalyst. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. To this mixture, 200 parts by mass of methyl ethyl ketone was added as a solvent and mixed uniformly by stirring. The thermosetting resin composition thus obtained was subjected to the same drying treatment and pressure treatment as in Example 1 to obtain a sheet-like heat conductive layer having a thickness of 100 μm.

Next, 230 parts by mass of methyl ethyl ketone was added as a solvent to 100 parts by mass of bisphenol A epoxy resin (JER1007 manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and the mixture was stirred to uniformly distribute the thermosetting resin in the solvent. It was dissolved in To the resulting mixture, scale-like boron nitride particles (PT110, manufactured by Momentive) with an average particle size of 45 μm were added as a plate-shaped filler to the total volume of the thermosetting resin, plate-shaped filler, and curing catalyst. The content was 50% by volume. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 100° C. for 5 minutes. The solvent in the mixture was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 120° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like voltage-resistant layer having a thickness of 150 μm. When this voltage-resistant layer was confirmed using an electron microscope, it was confirmed that the scale-like boron nitride particles in the voltage-resistant layer were oriented in the horizontal direction.

Next, 50 parts by mass of methyl ethyl ketone was added as a solvent to 100 parts by mass of bisphenol A epoxy resin (JER828US manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin, and the mixture was stirred to uniformly distribute the thermosetting resin in the solvent. It was dissolved in Alumina particles ("A-43-M" manufactured by Showa Denko) with an average particle size of 1 μm as a thermally conductive filler were added to the resulting mixture as a thermally conductive filler. The content was 20% by volume. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied to a sheet-like member in which the thermally conductive layer and the voltage-resistant layer of Example 3 were laminated together using a vacuum laminating device, and was doctored to a thickness of 100 μm. It was applied using the blade method. Then, by heating the thermally conductive layer, voltage-resistant layer, and adhesive layer at 100°C for 2 minutes using a vacuum laminating device, an insulating layer in which the thermally conductive layer, voltage-resistant layer, and adhesive layer are integrated is formed. Got a sheet. The insulating sheet according to Example 3 was obtained by heating and curing the obtained insulating sheet at 160° C. for 2 hours.

(Example 4)
The same thermal conductive layer as in Example 3 was used as the thermal conductive layer. The same voltage-resistant layer as in Example 3 was used as the voltage-resistant layer. The following adhesive layer was used.

By adding 50 parts by mass of methyl ethyl ketone as a solvent to 100 parts by mass of bisphenol A type epoxy resin ("jER1001" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin and stirring, the thermosetting resin was uniformly dissolved in the solvent. Ta. Into the resulting mixture, alumina particles ("A-12C" manufactured by Showa Denko) with an average particle size of 85 μm are added as a thermally conductive filler to the total volume of the thermosetting resin, thermally conductive filler, and curing catalyst. It was blended so that the amount was 15% by volume. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 100° C. for 5 minutes. The solvent in the mixture was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 120° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like fixed layer having a thickness of 200 μm. Then, the same lamination treatment and heat treatment as in Example 1 were performed to obtain an insulating sheet according to Example 4.

(Example 5)
The same thermal conductive layer as in Example 3 was used as the thermal conductive layer. The same voltage-resistant layer as in Example 3 was used as the voltage-resistant layer. The following adhesive layer was used.

By adding 100 parts by mass of methyl ethyl ketone as a solvent to 100 parts by mass of bisphenol A type epoxy resin ("jER828US" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin and stirring, the thermosetting resin was uniformly dissolved in the solvent. Ta. Into the resulting mixture, alumina particles ("A-12C" manufactured by Showa Denko) with an average particle size of 85 μm are added as a thermally conductive filler to the total volume of the thermosetting resin, thermally conductive filler, and curing catalyst. Alumina particles (“A-43-M” manufactured by Showa Denko) with an average particle size of 1 μm were added to the total volume of the thermosetting resin, thermally conductive filler, and curing catalyst so that the amount was 10% by volume. It was blended so that it was 20% by volume. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied to a sheet-like member in which the thermally conductive layer and the voltage-resistant layer of Example 3 were laminated together using a vacuum laminating device, and was doctored to a thickness of 100 μm. It was applied using the blade method. Then, by heating the thermally conductive layer, voltage-resistant layer, and adhesive layer at 100°C for 2 minutes using a vacuum laminating device, an insulating layer in which the thermally conductive layer, voltage-resistant layer, and adhesive layer are integrated is formed. Got a sheet. The insulating sheet according to Example 5 was obtained by heating and curing the obtained insulating sheet at 160° C. for 2 hours.

(Example 6)
The same thermal conductive layer as in Example 3 was used as the thermal conductive layer. The same fixed layer as in Example 5 was used as the fixed layer. The following voltage-resistant layers were used.

By adding 180 parts by mass of methyl ethyl ketone as a solvent to 100 parts by mass of bisphenol A type epoxy resin ("jER828US" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin and stirring, the thermosetting resin was uniformly dissolved in the solvent. Ta. To the resulting mixture, scale-like boron nitride particles (PT110, manufactured by Momentive) with an average particle size of 45 μm were added as a plate-shaped filler to the total volume of the thermosetting resin, plate-shaped filler, and curing catalyst. Nanosilica particles having an average particle size of 0.3 μm were blended in an amount of 50% by volume and 5% by volume based on the total volume of the thermosetting resin, plate filler, and curing catalyst. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating it at 80° C. for 5 minutes. The solvent in the coating was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 100° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like voltage-resistant layer having a thickness of 150 μm. When this voltage-resistant layer was confirmed using an electron microscope, it was confirmed that the scale-like boron nitride particles in the voltage-resistant layer were oriented in the horizontal direction. Then, the same lamination treatment and heat treatment as in Example 1 were performed to obtain an insulating sheet according to Example 6.

(Example 7)
The same thermal conductive layer as in Example 3 was used as the thermal conductive layer. The same fixed layer as in Example 5 was used as the fixed layer. The following voltage-resistant layers were used.

By adding 150 parts by mass of methyl ethyl ketone as a solvent to 100 parts by mass of bisphenol A type epoxy resin ("jER828US" manufactured by Mitsubishi Chemical Corporation) as a thermosetting resin and stirring, the thermosetting resin was uniformly dissolved in the solvent. Ta. 20 parts by mass of bisphenol A type phenoxy resin ("1256B40" manufactured by Mitsubishi Chemical Corporation) was added to the resulting mixture. In addition, as a plate-shaped filler, scaly boron nitride particles (PT110 manufactured by Momentive) with an average particle diameter of 45 μm were used in an amount of 50% by volume based on the total volume of the thermosetting resin, plate-shaped filler, and curing catalyst. It was blended into. Furthermore, 5 parts by mass of an imidazole catalyst ("2E4MZ" manufactured by Shikoku Kasei Co., Ltd.) was blended with 100 parts by mass of bisphenol A epoxy resin as a curing catalyst for the thermosetting resin. This mixture was mixed uniformly. The thermosetting resin composition thus obtained was applied onto a PET substrate with a thickness of 50 μm using a doctor blade method, and the applied material was dried by heating at 80° C. for 5 minutes. The solvent in the mixture was removed. Thereafter, the coated and dried product was subjected to pressure treatment under reduced pressure at 100° C. for 2 minutes at a pressure of 1 MPa using a vacuum laminating apparatus, thereby obtaining a sheet-like voltage-resistant layer having a thickness of 150 μm. When this voltage-resistant layer was confirmed using an electron microscope, it was confirmed that the scale-like boron nitride particles in the voltage-resistant layer were oriented in the horizontal direction. Then, the same lamination treatment and heat treatment as in Example 1 were performed to obtain an insulating sheet according to Example 7.

(Comparative example 1)
By impregnating liquid varnish into insulating paper ("NTN-272(S)" manufactured by Nitto Shinko Co., Ltd.), which is a lamination of 50 μm thick aramid paper, 88 μm thick PET, and 50 μm thick aramid paper. An insulating sheet according to Comparative Example 1 was obtained.

(Comparative example 2)
An insulating sheet according to Comparative Example 2 was obtained by applying the thermally conductive layer and adhesive layer of Example 1 to a PET film having a thickness of 188 μm. The thickness of the thermally conductive layer was 100 μm, and the thickness of the fixed layer was 200 μm.

(Comparative example 3)
By setting the thickness of the heat conductive layer of Example 1 to 150 μm and stacking three heat conductive layers, an insulating sheet having a thickness of 450 μm according to Comparative Example 3 was obtained.

(Test method)
Thermal conductivity and dielectric breakdown electric field (BDE) of the insulating sheets of Examples 1 to 7 and Comparative Examples 1 to 3 were measured using the test methods shown below. In addition, the insulating sheets obtained in Examples 1, 4, and 7 and Comparative Examples 1 to 3 were attached to the surface of the stator core, and the thermal resistance value and dielectric breakdown electric field of the stator in a state where the electric wire was wound around the stator core via the insulating sheet. was measured.

[Thermal conductivity of insulation sheet]
The thermal conductivity in the thickness direction of the insulating sheet was measured using a steady method. The thermal conductivity measurement results are based on the thermal conductivity obtained with the insulating sheet of Comparative Example 1, and the relative value of the thermal conductivity obtained with the insulating sheet of each Example or each Comparative Example ([Each Example Thermal conductivity obtained in the insulating sheet of Example or each Comparative Example]/[Thermal conductivity obtained in the insulating sheet of Comparative Example 1] is shown in Table 1.

[Dielectric breakdown electric field of insulation sheet]
The dielectric breakdown electric field of the insulating sheet was calculated by dividing the dielectric breakdown voltage (BDV) measured by applying a voltage to the insulating sheet at a constant step-up of 1 kV/sec in oil by the thickness of the insulating sheet. . The results of this dielectric breakdown electric field are based on the dielectric breakdown electric field obtained with the insulation sheet of Comparative Example 1, and the relative value of the dielectric breakdown electric field obtained with the insulation sheet of each Example or each Comparative Example ([Each Example Or the value of [Dielectric breakdown electric field obtained with the insulation sheet of each comparative example]/[Dielectric breakdown electric field obtained with the insulation sheet of Comparative example 1]) is shown in Table 1.

[Stator thermal resistance value]
The thermal resistance value of the stator was calculated by dividing the thickness of the insulating sheet by the thermal conductivity of the insulating sheet. The results of the thermal resistance value of the stator are based on the thermal resistance value obtained with the stator equipped with the insulating sheet of Comparative Example 1, and the thermal resistance value obtained with the stator equipped with the insulating sheet of Examples 1, 4, 7 or each comparative example. Relative value of thermal resistance value ([thermal resistance value obtained with the stator equipped with the insulating sheet of Examples 1, 4, 7 or each comparative example]/[thermal resistance value obtained with the stator equipped with the insulating sheet of Comparative Example 1] The resistance value] is shown in Table 1.

[Stator breakdown electric field]
The dielectric breakdown field of the stator was calculated by dividing the dielectric breakdown voltage measured by applying a voltage to the stator at a constant pressure increase of 1 kV/sec in oil by the thickness of the insulating sheet. The results of the dielectric breakdown electric field are based on the dielectric breakdown electric field obtained with the stator equipped with the insulation sheet of Comparative Example 1, and the insulation breakdown electric field obtained with the stator equipped with the insulation sheet of Examples 1, 4, 7 or each comparative example. Relative value of breakdown electric field ([Dielectric breakdown electric field obtained in the stator equipped with the insulation sheet of Examples 1, 4, 7 or each comparative example]/[Dielectric breakdown electric field obtained in the stator equipped with the insulation sheet of Comparative example 1] ] values) are shown in Table 1.

As is clear from Table 1, the insulating sheets of Examples 1 to 7 that are provided with a thermally conductive layer containing a thermally conductive filler are different from the insulating sheet of Comparative Example 1 that is not provided with a thermally conductive layer that contains a thermally conductive filler. In comparison, it showed a high value in the evaluation item of thermal conductivity. Specifically, the thermal conductivity of the insulating sheets of Examples 1 and 2 is four times higher than that of the insulating sheet of Comparative Example 1. In addition, the thermal conductivity of the insulating sheets of Examples 3 to 7, which are provided with a voltage-resistant layer containing boron nitride particles with high thermal conductivity as a plate-shaped filler, is the same as that of the comparative example without a voltage-resistant layer containing boron nitride particles. Compared to 1, this is a dramatic improvement of 15 to 16 times. This shows that the thermally conductive filler and boron nitride particles with high thermal conductivity are effective in improving the heat dissipation properties of the insulating sheet.

As is clear from Table 1, the insulating sheets of Examples 1 to 7, which are provided with a voltage withstanding layer containing a plate-like filler, are different from the insulating sheets of Comparative Examples 2 and 3, which are not provided with a voltage-withstanding layer that contains a plate-like filler. In comparison, it showed a high value in the evaluation item of dielectric breakdown electric field. This shows that the plate-like filler is effective in improving the electrical insulation properties of the insulating sheet. In addition, the insulating sheets of Examples 1 to 7 showed values equal to or higher than those of the insulating sheet of Comparative Example 1 in the evaluation item of dielectric breakdown electric field.

As is clear from Table 1, the stators provided with the insulating sheets of Examples 1, 4, and 7 were all able to significantly lower the thermal resistance value compared to the stator provided with the insulated sheets of Comparative Example 1. Ta. These results are believed to be due to the fact that the insulation sheets of Examples 1, 4, and 7 were provided with a thermally conductive layer containing a thermally conductive filler, which significantly improved the thermal conductivity of the insulation sheets. It is inferred.

As is clear from Table 1, the stators using the insulating sheets of Examples 1, 4, and 7 have twice the dielectric breakdown electric field value compared to the stator using the insulating sheet of Comparative Example 1. I was able to improve it in the near future. On the other hand, the stators using the insulating sheets of Comparative Examples 2 and 3 had lower dielectric breakdown electric field values than the stators using the insulating sheets of Examples 1, 4, and 7. This result is because if the insulating sheet does not have a withstand voltage layer containing a plate-like filler, the wire will dig into the insulating sheet when the wire is wrapped around it, reducing the thickness of the insulating sheet, and the electrical insulation properties of the insulating sheet will decrease. However, if the insulating sheet has a voltage-resistant layer containing a plate-like filler, it can prevent the electric wires from digging into the insulating sheet and reduce the thickness of the insulating sheet, thereby ensuring the electrical insulation properties of the insulating sheet. It is presumed that this is the case.

The configurations shown in the embodiments above are merely examples, and can be combined with other known techniques, or can be combined with other embodiments, within the scope of the gist. It is also possible to omit or change part of the configuration.

1, 1A, 1B, 1C insulating sheet, 2 thermally conductive layer, 3 withstand voltage layer, 4, 4A, 4B, 4C fixed layer, 5 electric motor, 6 stator, 7 rotor, 8 shaft, 9 frame, 10 bracket, 10a hole , 11 stator core, 12 core back, 13 teeth, 14 slots, 15 coils, 16 electric wires, 21, 31, 41 thermosetting resin, 22, 42, 43 thermally conductive filler, 32 plate filler.

Claims (5)

An insulating sheet provided between the stator core and the coil of a stator comprising a stator core and a coil formed by winding electric wires in multiple layers around the stator core,
A thermally conductive layer laminated on the surface of the stator core and containing a thermosetting resin and a particulate thermally conductive filler having an average particle size of 40 μm or less;
A withstand voltage layer laminated on a surface of the thermally conductive layer facing away from the stator core and containing a thermosetting resin and a plate-shaped filler;
The withstand voltage layer is laminated on the side facing away from the stator core, to which the electric wires can be fixed, and contains only a thermosetting resin, or has an average particle size of 1 μm or less and has a gap between the electric wires. A fixing layer containing at least one of a thermally conductive filler smaller than the width and a thermally conductive filler having a particle size of 40 μm or more and larger than the width of the gap between the electric wires and a thermosetting resin;
Equipped with
The fluidity of the thermosetting resin of the thermally conductive layer and the thermosetting resin of the fixed layer during the heat treatment of the insulating sheet is the fluidity of the thermosetting resin of the voltage-withstanding layer during the heat treatment of the insulating sheet. higher than sex,
The thermosetting resin of the thermally conductive layer and the thermosetting resin of the fixed layer during the heat treatment of the insulating sheet are liquid resins or resins with a melt viscosity of 1 Pa·s or less,
An insulating sheet, wherein the thermosetting resin of the voltage-withstanding layer during heat treatment of the insulating sheet is a solid resin . The insulating sheet according to claim 1 , wherein the voltage-withstanding layer is a thermosetting resin composition containing a thermosetting resin and a plate-shaped filler having an average particle size of 10 μm or more. The voltage-withstanding layer is characterized in that it is a thermosetting resin composition containing a thermosetting resin, a plate-like filler with an average particle size of 20 μm or more, and nanoparticles with an average particle size of 300 nm or less. The insulating sheet according to claim 1 . A stator core formed of a magnetic material,
a coil formed by winding electric wire in multiple layers around the stator core;
The insulating sheet according to any one of claims 1 to 3 , which is disposed between the stator core and the coil;
A stator characterized by comprising: A method for manufacturing a stator according to claim 4 , comprising:
arranging the insulating sheet and the coil in slots provided in the stator core;
After the arranging step, a fixing step of heating the insulating sheet to fix the insulating sheet to the stator core and the coil;
A method for manufacturing a stator, comprising:

Images