Varnish resin composition for winding impregnation and method for manufacturing the same

Abstract

To obtain a varnish resin composition that achieves both excellent heat radiation properties and insulating properties.SOLUTION: A varnish resin composition for winding impregnation is provided which contains (a) unsaturated polyester, (b) a cross-linking agent and / or a reaction diluent, and (c) inorganic filler. The difference in Hansen solubility parameter between the (a) and the (c), ΔSP1, is ΔSP1<6.3. The difference in Hansen solubility parameter between the (b) and the (c), ΔSP2, is ΔSP2<6.3. A varnish resin-filled coil filled with the same, a rotary machine, and a selection method and a manufacturing method for a varnish resin composition for winding impregnation, are provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a varnish resin composition for impregnating windings and a method for producing the same. In particular, the present invention relates to a varnish resin composition for impregnating windings, which is excellent in heat dissipation and insulation properties, and a method for producing the same.

Background Art

[0002] Conventionally, coils incorporated in motors, generators, etc. are subjected to insulation treatment with varnish to protect the windings. The main purpose of this insulation treatment is insulation between the windings and the iron core (core) or the slot wall and between the windings. In addition to this, various functions such as physical support of the windings, transfer of heat generated from the windings to the slot wall, and covering of pinholes and processing scratches of the winding wires can be imparted to the coil by the insulation treatment.

[0003] There is known a heat-conductive heat-resistant insulating material-filled coil including an iron core, a winding wound around the iron core, and a heat-conductive heat-resistant insulating material filled between the iron core and the winding and / or between the windings, wherein the heat-conductive heat-resistant insulating material is a cured product of a thermosetting resin composition containing a phenolic hydroxyl group-containing polyamide resin (A), an epoxy resin (B), and an inorganic filler (C) having a thermal conductivity of 20 W / m·K or more (see, for example, Patent Document 1).

[0004] There is known an unsaturated polyester resin composition for coil encapsulation, which contains 15 to 25% by mass of an unsaturated polyester resin and a crosslinking agent, 65 to 80% by mass of magnesium oxide having a purity of 95% by mass and an average particle diameter of 5 to 40 μm, 2 to 5% by mass of glass fiber, and 2 to 5% by mass of an additive (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, hybrid cars, electric vehicles, etc. have attracted attention for environmental protection measures. With the increasing output and miniaturization of coils incorporated in motors, generators, etc. mounted on these vehicles, heat dissipation measures from the winding have become more important than ever. How to dissipate heat from the coil in a short time is crucial for heat dissipation measures from the winding.

[0007] Since the composition disclosed in Patent Document 1 uses a high molecular weight resin, it has a high viscosity, and the filling property between windings decreases in resin casting / impregnation under atmospheric pressure, resulting in the mixing of voids between windings and a high porosity. This leads to a decrease in insulation performance, and the problem is that it is impossible to achieve both high heat dissipation and insulation. In addition, the composition disclosed in Patent Document 2 is difficult to control dispersion, and there is a risk of insulation degradation.

[0008] In view of these prior arts, there is a need for a varnish resin composition that can achieve both excellent heat dissipation and insulation.

Means for Solving the Problems

[0009] As a result of intensive studies, the present inventors have found that a varnish resin composition containing components satisfying specific Hansen solubility parameter conditions can achieve both heat dissipation and insulation, and thus have completed the present invention.

[0010] According to one embodiment, the present invention relates to a varnish resin composition for winding impregnation, comprising: (a) an unsaturated polyester, (b) a reactive or non-reactive diluent, and (c) an inorganic filler, wherein the difference ΔSP1 in Hansen solubility parameter between (a) and (c) satisfies ΔSP1 < 6.3, and the difference ΔSP2 in Hansen solubility parameter between (b) and (c) satisfies ΔSP2 < 6.3.

[0011] In the varnish resin composition for impregnating the winding, it is preferable that the component (c) is at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, magnesium oxide, silicon carbide, and silicon nitride.

[0012] In the varnish resin composition for impregnating the winding, it is preferable that the component (c) is a coated inorganic filler coated with a surface modifier.

[0013] In the varnish resin composition for impregnating the winding, it is preferable that the component (b) includes a vinyl group-containing compound, a methacrylate group-containing compound, an acrylate group-containing compound, or an aromatic hydrocarbon compound substituted with a methyl group.

[0014] According to another embodiment of the present invention, there is provided a coil including: an iron core provided with slots; a winding wound around the iron core and accommodated in the slots; and the above-described varnish resin composition for impregnating the winding impregnated in the slots.

[0015] According to still another embodiment of the present invention, there is provided a rotating machine, a generator, a linear motor, a transformer, or a reactor including the above-described coil.

[0016] According to yet another embodiment of the present invention, there is provided a method for designing a varnish resin composition for impregnating a winding, including: a step of obtaining Hansen solubility parameters of (a) an unsaturated polyester, (b) a reactive or non-reactive diluent, and (c) an inorganic filler; and a step of selecting (a), (b), and (c) such that a difference ΔSP1 in Hansen solubility parameters between the component (a) and the component (c) satisfies ΔSP1 < 6.3, and a difference ΔSP2 in Hansen solubility parameters between the component (b) and the component (c) satisfies ΔSP2 < 6.3.

[0017] According to still another embodiment of the present invention, there is provided a method for manufacturing a varnish resin composition for impregnating windings, the method including a step of designing a varnish resin composition for impregnating windings by the aforementioned design method, and a step of preparing a resin composition using the selected (a), (b), and (c).

Advantages of the Invention

[0018] According to the present invention, it is possible to obtain a varnish resin composition for impregnating windings that achieves both excellent heat dissipation and insulation properties.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0020] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[0021] 1. Varnish Resin Composition for Impregnating Windings According to a first embodiment of the present invention, there is provided a varnish resin composition for impregnating windings. The varnish resin composition for impregnating windings contains the following (a), (b), and (c) as essential components, and the Hansen solubility parameters thereof satisfy a predetermined relationship. (a) Unsaturated polyester (b) Reactive or non-reactive diluent (c) Inorganic filler In the following description of the present embodiment, the varnish resin composition for impregnating windings may be abbreviated and described as a varnish resin composition.

[0022] (a) Unsaturated polyester Unsaturated polyester is a precursor of unsaturated polyester resin and may generally be a polycondensate of a divalent unsaturated acid and glycol. The unsaturated acid component used here is not particularly limited. For example, unsaturated acids such as maleic acid, maleic anhydride, fumaric acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, and saturated acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic acid, hexahydrophthalic anhydride, adipic acid, etc. may be mentioned, and these can be used alone or in plurality. The glycol component is not particularly limited. For example, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, 1,3 - butanediol, neopentyl glycol, glycerin, pentaerythritol, polyether polyalcohol, tris(2 - hydroxyethyl) isocyanurate, etc. may be mentioned, and these can be used alone or in plurality. Further, the unsaturated polyester of the present invention is also intended to include a modified unsaturated polyester obtained by adding a modifying component other than the thermosetting polyester resin and modifying it as necessary. Examples of the modifying component of the thermosetting polyester include linseed oil, soybean oil, tall oil, petroleum resin, xylene resin, dicyclopentadiene, etc., and these can be used alone or in a mixture of two or more. The type and molecular weight of the unsaturated polyester are not particularly limited, and any unsaturated polyester can be used as long as the Hansen solubility parameters of the unsaturated polyester and the inorganic filler satisfy a predetermined relationship.

[0023] (b) Reactive or non - reactive diluent The reactive diluent is a compound that functions as a copolymerizable monomer capable of bonding to the unsaturated bond of the unsaturated polyester. The reactive diluent may be a compound containing a vinyl group, a compound containing a methacrylate group, or a compound containing an acrylate group. For example, styrene, diallyl phthalate, triallyl cyanurate, methyl methacrylate, vinyl acetate, etc. may be mentioned, but are not limited thereto. The reactive diluent reacts with the unsaturated polyester in (a) to crosslink the molecules of a plurality of unsaturated polyesters to form a cured product.

[0024] A non-reactive diluent is a compound that does not react with an unsaturated polyester and functions as a solvent. Volatile organic solvents such as aromatic hydrocarbon compounds substituted with methyl groups can be used, for example, toluene, xylene, etc., but are not limited thereto. The non-reactive diluent volatilizes and decreases during the curing reaction. However, usually, a part remains inside the cured product.

[0025] The varnish resin composition may contain either a reactive diluent or a non-reactive diluent, or both. Also, each of the reactive diluent and the non-reactive diluent may be composed of one type of compound or may be a mixture of two or more types of compounds. Even when the varnish resin composition does not contain a reactive diluent, if the Hansen solubility parameters of the non-reactive diluent and the inorganic filler satisfy a predetermined relationship, an unsaturated polyester resin having a desired function can be obtained.

[0026] (c) Inorganic filler An inorganic filler is a compound that imparts heat dissipation properties to the varnish resin composition. The inorganic filler may generally be a metal oxide, a metal nitride, a metal carbide, etc., and may be at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, magnesium oxide, silicon carbide, and silicon nitride. Therefore, it is also possible to use a combination of two or more different compounds. The shape of the inorganic filler is not particularly limited, but may be spherical, needle-shaped, plate-shaped, etc. Also, the inorganic filler may have an average particle diameter of 0.1 to 500 μm, preferably 5 to 300 μm. The average particle diameter can refer to the volume-based median diameter determined by the laser diffraction / scattering method, which is the diameter at which the cumulative volume frequency is 50%.

[0027] The inorganic filler may be an untreated inorganic filler composed of the above metal oxides, metal nitrides, and / or metal carbides without surface modification. Alternatively, it may be an inorganic filler with a surface modifier coated on its surface. The surface modifier may be any compound capable of improving the adhesion between the inorganic filler and the unsaturated polyester resin. Examples of such surface modifiers include, but are not limited to, silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, fatty acids, etc. Further, in the inorganic filler with a surface modifier coated thereon, the surface of the metal oxide, metal nitride, and / or metal carbide may be completely covered with the surface modifier, or a part of the metal oxide, metal nitride, and / or metal carbide may be exposed. Examples of a silane coupling agent, which is an example of a preferred surface modifier, include vinyltrialkoxysilane, glycidoxypropyltrialkoxysilane, methacryloyloxypropyltrialkoxysilane, aminopropyltrialkoxysilane, and mercaptopropyltrialkoxysilane. In these silane coupling agents, the alkoxysilane may be methoxysilane, ethoxysilane, or propoxysilane, or may be a silane compound containing methoxy groups, ethoxy groups, or propoxy groups in any combination, but is not limited thereto.

[0028] In addition to the above essential components (a), (b), and (c), the varnish resin composition may optionally contain additives that can usually be contained in the varnish resin composition. Examples of the additives include, but are not limited to, flame retardants, antioxidants, pigments for coloring the resin, plasticizers, and silicone elastomers for improving crack resistance. These optional components and their addition amounts can be appropriately determined by those skilled in the art according to the specifications required for the resin.

[0029] The Hansen solubility parameter (HSP) is a value specific to a substance and is represented by the following formula (1). δ=(δ D 2 +δP 2 +δ H 2 ) 1 / 2 (1) Assume that the cohesive energy term of the Hildebrand solubility parameter is given by the sum of the energies related to London dispersion forces, dipole-dipole forces, and hydrogen bonding forces, and it is a solubility parameter divided into three components. In the formula, δ D is the energy related to the London dispersion force term component, δ P is the energy related to the dipole-dipole force term component, δ H represents the energy related to the hydrogen bonding force term component. In the present invention, (a) each component term of the HSP of the unsaturated polyester is δ Da , δ Pa , δ Ha , (b) each component term of the reactive or non-reactive diluent is δ Db , δ Pb , δ Hb , (c) the HSP of the inorganic filler is δ Dc , δ Pc , δ Hc . Then, the difference ΔSP1 in HSP between (a) and (c) and the difference ΔSP2 in HSP between (b) and (c) can be expressed as follows.

Equation

[0030] (a) Unsaturated polyester, (b) reactive or non-reactive diluent, and (c) inorganic filler's HSP can be determined by experimental methods and computational methods. For (a) and (b), when the chemical structure is known, it can be determined by computational methods, which can be based on the atomic group contribution method and the molecular group contribution method (Density and Viscosity of Binary Mixtures of Diethyl Carbonate with Alcohols at (293.15 to 363.15) K and Predictive Results by UNIFAC-VISCO Group Contribution Method, J. Chem. Eng. Data 2006, 51, 4, 1345-1351), and can be carried out using the Hansen solubility parameter software HSPiP (Hansen Solubility Parameter in Practice). When the chemical structure is unknown, it can be determined by experimental methods, for example, it can be carried out based on the Hansen solubility sphere method (Using Hansen solubility parameters to correlate solubility of C60 fullerene in organic solvents and in polymers, Carbon 42(8):1591-1597). For (c), it can be determined by experimental methods and can be carried out based on the penetration rate method (Functional composite material design using Hansen solubility parameters, Results in Materials 4 (2019) 100046). It has been confirmed that the HSP determined by experimental methods and the HSP determined by computational methods are both of the same level. Therefore, either can be used to obtain ΔSP1 and ΔSP2.

[0031] Also, for example, (a) when the unsaturated polyester is composed of a mixture of two or more unsaturated polyesters having different HSPs, when determining the HSP by a calculation method, for each component of δ Da of each unsaturated polyester, δ Pa of each unsaturated polyester, and δ Ha of each unsaturated polyester, the sum of the values obtained by multiplying by the volume fraction can be used as the δ Da of the mixture, δ Pa of the mixture, and δ Ha of the mixture. When determining the HSP by an experimental method, it is only necessary to conduct an experiment on the mixture, which is no different from the case of a single unsaturated polyester. The same applies to the HSP of (b) a reactive or non-reactive diluent and (c) an inorganic filler.

[0032] In the varnish resin composition, the content of component (b) can be appropriately adjusted within a range that does not reduce the moldability and heat resistance of the winding impregnated portion. For example, the content of component (b) is preferably 20 parts by mass to 300 parts by mass, more preferably 50 parts by mass to 250 parts by mass, based on 100 parts by mass of component (a). Also, component (c) can be added so as to be 1 to 400 parts by mass, preferably 10 to 150 parts by mass, and more preferably 50 to 100 parts by mass, based on 100 parts by mass of the total mass of components (a) and (b).

[0033] The preparation of the varnish resin composition can be carried out by mixing the above components (a) and (b) and dispersing component (c) in the mixture. The dispersion of component (c) can be carried out by ordinary methods. In the obtained varnish resin composition, the primary particles of component (c) are uniformly dispersed in the mixture of components (a) and (b). The uniform dispersion of the primary particles can be confirmed by a particle size distribution meter based on the laser diffraction / scattering method or the dynamic light scattering method.

[0034] The varnish resin composition according to the present embodiment can be used for impregnating a winding wound around an iron core, ensuring insulation between the iron core and the winding and between a plurality of windings, and ensuring high heat dissipation. Conventionally, the cured product of the varnish used for insulation and the like in a coil had a thermal conductivity of about 0.2 W / mK or less, which was insufficient for heat dissipation. The varnish resin composition according to the present embodiment can control the balance of intermolecular forces between the resin and the inorganic filler by satisfying a specific value of ΔSP1, and can control the balance of intermolecular forces between the reactive or non-reactive diluent and the inorganic filler by satisfying a specific value of ΔSP2. As a result, uniform dispersion of the inorganic filler in the varnish resin composition becomes possible, and high thermal conductivity of the varnish resin composition can be achieved while ensuring insulation. Therefore, it is useful for manufacturing a stator coil and can be used in a rotating machine or a generator.

[0035] 2. Coil and rotating machine, generator, linear motor, transformer, reactor using the same According to the second embodiment of the present invention, it relates to a coil and a rotating machine, a generator, a linear motor, a transformer, or a reactor using the same. The coil is preferably a stator coil and includes the following. (A) An iron core provided with slots (B) A winding wound around the iron core and accommodated in the slot (C) The winding impregnating varnish resin composition according to the first embodiment impregnated in the slot

[0036] FIG. 1 is a partial cross-sectional view of the coil according to the present embodiment. Referring to FIG. 1, the core 2 is provided with slots 3. A plurality of windings 4 wound around the core 2 are accommodated in the slots 3. The core 2 may generally be a silicon steel sheet, or a silicon steel sheet with an insulating material coated on its surface. The winding 4 may generally be a copper wire, and those commonly used in the manufacture of coils can be used. Inside the slot 3, the varnish resin composition 1 for impregnating the winding according to the first embodiment is impregnated and cured. The varnish resin composition 1 for impregnating the winding is cured in a state of being filled between the core 2 and the winding 4 and between the plurality of windings, insulating between these conductive members.

[0037] The manufacturing method of the coil according to the present embodiment will be described. By fitting a bundle of windings 4 into the slot 3 in a state of being wrapped with insulating paper (not shown), it is accommodated in the slot 3. Next, the varnish resin composition 1 for impregnating the winding according to the first embodiment is impregnated so that the composition contacts the winding 4. As a result, the insulating paper is disposed on the inner surface of the slot 3, and the varnish resin composition 1 for impregnating the winding is filled between the plurality of windings 4 inside the insulating paper. By curing this at a temperature of 100 to 160°C for about 2 to 30 hours in a state of normal pressure, the coil according to the present embodiment can be manufactured.

[0038] The coil according to the present embodiment can be used as a stator or rotor of a rotating machine or a generator, a stator or mover of a linear motor, a transformer, or a reactor. In particular, by using the varnish resin composition 1 for impregnating the winding, which is excellent in thermal conductivity and insulation according to the first embodiment, it can be used even in rotating machines and generators with excellent reliability, small size, and large heat generation. The rotating machine can be incorporated and used, for example, in a drive system of a ship or a vehicle for electric propulsion.

[0039] 3. Design method of varnish resin composition for impregnating winding According to the third embodiment, the present invention relates to a method for designing a varnish resin composition for impregnating windings. The design method relates to a design method capable of selecting a combination of constituent components of a varnish resin composition for impregnating windings, which is excellent in heat dissipation and insulation properties and is particularly useful for small rotating machines. The design method includes the following steps. (i)(a) Obtaining the Hansen solubility parameters of an unsaturated polyester, (b) a reactive or non-reactive diluent, and (c) an inorganic filler (ii) Selecting (a), (b), and (c) such that the difference ΔSP1 in Hansen solubility parameters between (a) and (c) is ΔSP1 < 6.3, and the difference ΔSP2 in Hansen solubility parameters between (b) and (c) is ΔSP2 < 6.3

[0040] In step (i), the Hansen solubility parameters (HSP) of candidate (a) unsaturated polyester, (b) reactive or non-reactive diluent, and (c) inorganic filler are obtained. The preferred candidate (a), (b), and (c) components are as described in the first embodiment. Also, as for the method of obtaining HSP, the method described in the first embodiment can be used. Either obtaining HSP by calculation or obtaining HSP by experiment may be performed, or both may be performed.

[0041] In step (ii), a combination of (a), (b), and (c) components is selected such that the HSP of the (a), (b), and (c) components obtained in step (i) satisfies ΔSP1 < 6.3 and ΔSP2 < 6.3. As described in the first embodiment, for a combination of (a), (b), and (c) components where both ΔSP1 and ΔSP2 are less than 6.3, ΔSP1 and ΔSP2 may be values close to 0 or values close to 6.3, and the relationship between ΔSP1 and ΔSP2 is not limited either.

[0042] According to this embodiment, components of a varnish resin composition that can be used in the manufacture of a stator coil and exhibit high insulation and heat dissipation properties can be selected. By using HSP as an index, it is possible to perform evaluation by calculation, and it is advantageous in that the combination of components can be selected from a large number of compounds in a simple manner.

[0043] 4. Method for manufacturing a varnish resin composition for impregnating a winding According to the fourth embodiment of the present invention, it relates to a method for designing a varnish resin composition for impregnating a winding. The manufacturing method includes the following steps. (I) Step of designing a varnish resin composition for impregnating a winding by the design method described in the third embodiment (II) Step of preparing a resin composition using the selected (a), (b), and (c)

[0044] Step (I) can be carried out as described in the third embodiment. Also, step (II) can be carried out by the method described as the method for preparing a resin composition in the first embodiment.

Examples

[0045] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the present invention.

[0046] Components (a), (b), and (c) whose HSP values satisfy predetermined conditions were selected, and varnish resin compositions of examples and comparative examples were prepared. As component (a), unsaturated polyester WP-2952F-2G(Y) (manufactured by Showa Denko Materials) was used in all examples and comparative examples. The HSP of component (a) is δ Da is 20, δ Pa is 10.6, δ HaIt was 3.1, and as a result of measurement by the Hansen solubility sphere method, it was 22.8. For component (b), styrene or toluene shown in Table 1 below was used. For component (c), the compounds shown in Table 1 below and, when applicable, a surface modifier were used. For the inorganic filler coated with the surface modifier, HSP was measured in the same manner as component (a) above in the coated state. In the table, for alumina, AO-509 manufactured by Admatechs Co., Ltd. was used except that DAK-2 manufactured by Bestry Co., Ltd. was used in Comparative Example 2. Both DAK-2 and AO-509 had an average particle size of 200 μm. As the surface modifier, methyltriethoxysilane was manufactured by Momentive, and the others were manufactured by Shin-Etsu Chemical Co., Ltd. The mass ratio of components (a), (b), and (c) of the varnish resin composition was 100:10:30. For the inorganic filler coated with the surface modifier, the mass ratio of the inorganic filler to the surface modifier was 100:5.

[0047] The varnish resin composition was prepared by mixing components (a), (b), and (c) in the above mass ratio and stirring for 10 minutes using a planetary stirring mill. The prepared varnish resin composition was reacted at 130 °C for 3 hours to obtain a cured varnish resin. The sample for measuring the partial discharge inception electric field and the dielectric breakdown electric field was in a cylindrical shape with a diameter of 3 cm and a height of 4 cm with a hemispherical electrode embedded. For the sample for measuring the thermal conductivity, a 10 mm square sample piece was cut out, and carbon spray was applied to both sides for blackening treatment.

[0048] The evaluation method for the dispersibility of the inorganic filler after curing was to cut out a cross-section of the cured product, prepare a sample subjected to polishing treatment, and obtain a distribution image of the inorganic filler in the cured product with a scanning electron microscope (SEM). This was subjected to image processing to calculate the dispersion degree D, which was used as a value indicating the dispersibility. The dispersion degree D was defined as D = σ / d, where the centers of gravity of adjacent inorganic fillers on the SEM image were connected, the average of the respective distances was d, and the standard deviation was σ. The closer the dispersion degree is to zero, the more uniformly the inorganic filler is dispersed in the observation region.

[0049] The method for evaluating the partial discharge inception electric field and the breakdown electric field of the varnish resin cured product is as follows: a hemispherical electrode is used as the electrode, a voltage is applied to the varnish resin cured product at a voltage rising rate of 200 V / s, and the voltage at which a discharge of 1 pC or more occurs is obtained and taken as the partial discharge inception voltage. The obtained partial discharge inception voltage is divided by the electrode distance to obtain the partial discharge inception electric field.

[0050] The method for evaluating the thermal conductivity of the varnish resin cured product was measured by the flash method. The thermal conductivity of the cured product was calculated from the density measured by the water substitution method, the specific heat measured by the DSC method, and the thermal diffusivity measured by the flash method.

[0051] Table 1 shows the types and HSPs of components (b) and (c) of the varnish resin compositions used in the examples and comparative examples, and Table 2 shows ΔSP1, ΔSP2, and the evaluation results of the varnish resin cured products. In the tables, "-" means that the corresponding component is absent or the corresponding numerical value or result does not exist. The HSP values of the inorganic fillers indicate the HSP values of the inorganic fillers after treatment with the surface modifier in the examples and comparative examples using the surface modifier, and the HSP values of the inorganic fillers themselves in the examples and comparative examples without using the surface modifier.

[0052]

Table 1

[0053]

Table 2

[0054] Next, the relationship between ΔHSP between two different materials, at least one of which is an inorganic filler, and the degree of dispersion of the inorganic filler was investigated. ΔHSP was calculated by molecular dynamics simulation from the chemical structures of the filler and the other material (resin, solvent), and the distribution (dispersion state) of the two materials obtained by simulation from the chemical structures was represented by the previously defined degree of dispersion D and plotted. Also, for the purpose of confirming the validity of the calculation, for two points, samples were actually prototyped and the degree of dispersion was measured on SEM images. The results are shown in Figure 2. In the graph, the plots indicated by A and B show the measured data. For the sample of A, it was visually confirmed on the SEM image that the filler was uniformly dispersed in the field of view and had good dispersibility (SEM image not shown). On the other hand, for the sample of B, it was visually confirmed on the SEM image that there were clearly separated areas where the filler was aggregated and areas where the filler was absent in the field of view, indicating poor dispersibility (SEM image not shown). From Figure 2, it was confirmed that the threshold value of ΔHSP between two materials that can improve the degree of dispersion of the inorganic filler is 6.3. Also, it was confirmed by simulation and experiment that the curve shape and threshold value of this graph are the same regardless of the type of compound or surface modifier constituting the inorganic filler and the type of resin or solvent that is the other material. Therefore, it was confirmed that by setting both ΔSP1 and ΔSP2 to less than 6.3, a varnish resin composition with good dispersibility that achieves both excellent heat dissipation and insulation can be obtained.

Industrial Applicability

[0055] The varnish resin composition for impregnating windings according to the present invention can be used in the manufacture of varnish resin-impregnated coils and is useful as a member such as a rotating machine or a generator.

Explanation of Symbols

[0056] 1 Varnish resin composition for impregnating windings, 2 Iron core, 3 Slot, 4 Winding

Claims

1. (a) an unsaturated polyester, (b) a reactive or non-reactive diluent, and (c) an inorganic filler are included, the difference ΔSP1 in Hansen solubility parameters between the (a) and the (c) is such that ΔSP1 < 6.3, and the difference ΔSP2 in Hansen solubility parameters between the (b) and the (c) is such that ΔSP2 < 6.3, a varnish resin composition for impregnating coils.

2. The varnish resin composition for impregnating coils according to claim 1, wherein the (c) is at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, magnesium oxide, silicon carbide, and silicon nitride.

3. The varnish resin composition for impregnating coils according to claim 1, wherein the (c) is a coated inorganic filler coated with a surface modifier.

4. The varnish resin composition for impregnating coils according to claim 1, wherein the (b) includes a vinyl group-containing compound, a methacrylate group-containing compound, an acrylate group-containing compound, and / or an aromatic hydrocarbon compound substituted with a methyl group.

5. a core provided with slots, a coil wound around the core and accommodated in the slots, and the varnish resin composition for impregnating coils according to claim 1 impregnated in the slots are provided, a coil.

6. A rotary machine, a generator, a linear motor, a transformer or a reactor including the coil according to claim 5.

7. A method for designing a varnish resin composition for impregnating coils, comprising: a step of obtaining Hansen solubility parameters of (a) an unsaturated polyester, (b) a reactive or non-reactive diluent, and (c) an inorganic filler; and a step of selecting (a), (b), and (c) such that the difference ΔSP1 in Hansen solubility parameters between the (a) and the (c) is ΔSP1 < 6.3, and the difference ΔSP2 in Hansen solubility parameters between the (b) and the (c) is ΔSP2 < 6.3 are included, a method.

8. A method for manufacturing a varnish resin composition for impregnating coils, comprising: a step of designing a varnish resin composition for impregnating coils by the design method according to claim 7; and a step of preparing a resin composition using the selected (a), (b), and (c) are included, a method.

Images