Thermosetting resin composition and stator

Abstract

Provided is a thermosetting resin composition which is used for the purpose of forming a sealing member (resin sealing part (65)) in a stator (4) which has a stator core (41) that has a plurality of teeth (7) and a plurality of slots (8) alternately formed in the circumferential direction, a coil (9) that is wound in the slot (8) and housed in the slot (8), and the sealing member (resin sealing part (65)) that is provided inside the slot (8) so as to seal the coil (9). The thermosetting resin composition contains an epoxy resin, a curing agent, and an inorganic filler, D90 in the particle size distribution of the inorganic filler is 40 μm to 70 μm inclusive, and D10 in the particle size distribution of the inorganic filler is 0.1 μm to 1.0 μm inclusive.

Description

Thermosetting resin composition and stator

[0001] The present invention relates to a thermosetting resin composition and a stator.

[0002] A technology using a resin material for a stator core is described in Patent Document 1 (JP 2003-284277 A). This document describes a rotating electric machine having a stator in which multiple coils are wound at predetermined intervals around a stator core made of laminated electromagnetic steel sheets, a rotor rotatably held relative to the stator, and a cooling frame to which the stator is fixed, in which slots that form the winding portions of the stator are filled with a highly thermally conductive composite material made of a thermosetting resin whose resin component has an anisotropic structure. It is said that this configuration provides a rotating electric machine with good heat dissipation properties, as it easily transfers heat generated in the coils.

[0003] Japanese Patent Application Laid-Open No. 2003-284277

[0004] Incidentally, a resin composition, which is an insulating material, is sometimes filled between the stator and the coils housed in the slots of the stator, and there has been a demand for both insulation and the ability to fill the gap between the coils.

[0005] The present invention has been made in consideration of these circumstances, and aims to provide a technology that achieves both insulation and filling between the coils when a coil is placed in a slot and a resin composition is filled between the stator and the coil.

[0006] The present invention provides the following technologies. <1> A thermosetting resin composition used to form a sealing member in a stator having a stator core having a plurality of teeth and a plurality of slots arranged alternately in the circumferential direction, a coil wound around and housed in the slots, and a sealing member provided in the slot to seal the coil, the thermosetting resin composition comprising: an epoxy resin; a curing agent; and an inorganic filler, wherein the inorganic filler has a particle size distribution in which D90 is 40 μm or more and 70 μm or less and D10 is 0.1 μm or more and 1.0 μm or less. <2> The thermosetting resin composition according to <1>, wherein the ratio of D90 to D10 in the particle size distribution, D90 / D10, is 100 or more and 300 or less. <3> The thermosetting resin composition according to <1> or <2>, wherein the ratio of D90 to D50 in the particle size distribution, D90 / D50, is 4 or more and 8 or less. <4> The thermosetting resin composition according to any one of <1> to <3>, wherein the content of the inorganic filler is 90% by mass or more and 93% by mass or less, based on the total mass of the thermosetting resin composition. <5> The thermosetting resin composition according to any one of <1> to <4>, wherein the inorganic filler includes at least one selected from the group consisting of alumina, fused silica, and crystalline silica. <6> The thermosetting resin composition according to <4>, wherein the inorganic filler includes 60% by mass or more of alumina, based on the total mass of the thermosetting resin composition. <7> The thermosetting resin composition according to any one of <1> to <6>, wherein the gel time is 40 seconds or more and 100 seconds or less. <8> The thermosetting resin composition according to any one of <1> to <7>, wherein the thermal conductivity of a cured product of the thermosetting resin composition is 3.2 W / mK or more. <9> The thermosetting resin composition according to any one of <1> to <8>, wherein the epoxy resin comprises at least one selected from the group consisting of biphenyl-type epoxy resins, bisphenol-type epoxy resins, stilbene-type epoxy resins, novolac-type epoxy resins, multifunctional epoxy resins, phenol aralkyl-type epoxy resins, and naphthol-type epoxy resins. <10> The thermosetting resin composition according to any one of <1> to <9>, wherein the glass transition temperature is 175°C or higher.<11> A stator having a stator core having a plurality of teeth and a plurality of slots formed alternately in the circumferential direction, a coil wound around the slot and housed in the slot, and a sealing member provided in the slot to seal the coil, wherein the sealing member is made of a cured product of the thermosetting resin composition according to any one of <1> to <10>.

[0007] According to the present invention, when a coil is placed in a slot and a resin composition is filled between the stator and the coil, a technique can be provided that satisfies both the insulation property and the ability to fill the gap between the coils.

[0008] 1A and 1B are cross-sectional views of a motor in a direction perpendicular to the rotation axis direction, a longitudinal cross-sectional view of a motor in the rotation axis direction, an enlarged view of the periphery of a slot, and a cross-sectional view showing the inside of a slot.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and their description will be omitted where appropriate. In this specification, the numerical range "a to b" means "a or more and b or less" unless otherwise specified.

[0010] <Summary> In this embodiment, a technology is provided that achieves both insulation and inter-coil filling properties by specifying the particle size distribution (D90, D10, etc.) of an inorganic filler contained in a thermosetting resin composition used to form a sealing member that seals coils in slots in the stator of a rotating electrical machine such as a motor.

[0011] <Motor> Fig. 1 is a schematic cross-sectional view of motor 100 taken perpendicular to the rotational axis direction. Fig. 2 is a schematic cross-sectional view of motor 100 taken in the rotational axis direction. Fig. 3 is an enlarged view of the periphery of the slot (area X in Fig. 1), and is a schematic cross-sectional view of the portion where coil 9 protrudes from the end of slot 8. Fig. 4 is a cross-sectional view taken along line A-A in Fig. 3, showing the inside of slot 8.

[0012] The motor 100 includes a case 1 , and a rotor 2 , a stator 4 , and a coil 9 housed inside the case 1 .

[0013] <Case> The case 1 includes a cylindrical portion 1 a and side plate portions 1 b, 1 c that close both axial ends of the cylindrical portion 1 a. The case 1 can be made of, for example, an aluminum alloy (cast metal product), a resin material, or a combination thereof.

[0014] <Rotor> As shown in Figures 1 and 2, the rotor 2 is housed inside the case 1. As shown in Figure 2, a rotary shaft 3 is attached to the center of the rotor 2 as an output shaft. Both ends of the rotary shaft 3 are supported by the side plate portions 1b and 1c via bearings 3a. This allows the rotor 2 to rotate freely around the rotary shaft 3.

[0015] Permanent magnets 5 are installed inside the rotor 2. Specifically, as shown in Fig. 1, a plurality of (eight in this example) permanent magnets 5 are arranged at equal intervals on the same circumference, with the magnetic poles of adjacent permanent magnets 5 being set to be different from each other.

[0016] <Stator> The stator 4 includes a stator core 41 and coils 9 sealed in slots 8. The stator core 41 is formed by stacking and closely fixing multiple electromagnetic steel plates in the axial direction. As shown in FIG. 1 , when viewed from the axial end, the stator core 41 includes an annular yoke portion 6 and multiple teeth portions 7 extending from the yoke portion 6 toward the rotor 2 (inner periphery). The multiple teeth portions 7 are arranged at equal intervals in the circumferential direction. Here, as an example, as shown in FIG. 1 , 24 teeth portions 7 are provided. Slots 8 are provided between each tooth portion 7. The teeth portions 7 are also provided with a thin resin layer 50 formed by wrapping a resin composition around the teeth portions 7. The axial length of the stator 4 (stator core 41) is, for example, 100 mm to 200 mm. A motor 100 having a stator 4 of this size is suitable for use as a drive motor for an automobile.

[0017] <Coil> The coil 9 is a U-shaped rectangular wire wound so as to straddle the tooth portion 7 and be housed in two spaced-apart slots 8. Here, the coil 9 is housed in a liner member 20 arranged in the slot 8 in a distributed winding manner. The coil 9 has a coil body made of a good conductor such as copper and having a rectangular cross section, and a resin coating layer that coats the surface of the coil body. The resin coating layer can be made of the same material as that described below as the resin material for the resin sealing portion 65 and resin layer 50.

[0018] <Teeth portion> The teeth portion 7 is provided to correspond to the permanent magnets 5 of the rotor 2 described above, and by sequentially exciting each coil 9, the rotor 2 rotates due to attraction and repulsion with the corresponding permanent magnets 5.

[0019] The teeth 7 are tapered, with a larger circumferential width on the outer periphery and a smaller width on the inner periphery. Teeth tips 71 are formed at the inner periphery end of the teeth 7, facing each other along the circumferential direction so as to reduce the width of the slots 8.

[0020] <Slots> The slots 8 are spaces between adjacent teeth 7, and as shown in Figures 3 and 4, are provided so that the inner wall surfaces 72 of the teeth 7 that face each other in the radial direction are parallel to each other. The space between the tooth tips 71 forms the inner peripheral opening of the slot 8. The slot 8 has multiple coils 9 arranged on the outer peripheral side (the yoke portion 6 side) and a resin sealing portion 65 that fills the space in the slot 8 excluding the coils 9 and the resin layer 50.

[0021] <Resin Layer> As shown in Figures 3 and 4, resin layer 50 is formed by integrally wrapping a resin composition around the periphery of tooth portion 7 to cover it, and includes tooth inner surface resin layer 51 that covers inner wall surface 72 of tooth portion 7, tooth outer surface resin layer 52 that covers upper surface 75a and lower surface 75b of tooth portion 7, and yoke inner surface resin layer 53 that covers inner wall surface 62 of yoke portion 6.

[0022] Resin layer 50 is formed by insert molding to wrap around tooth portion 7 in a thin manner, thereby tightly fixing the stator 4, more specifically the multiple laminated electromagnetic steel sheets in tooth portion 7. Note that resin layer 50 does not necessarily have to wrap around tooth portion 7 in a thin manner, and tooth outer surface resin layer 52 may be omitted. By providing tooth inner surface resin layer 51 and yoke inner surface resin layer 53, insulation between coil 9 and the inner wall surface of slot 8 (inner wall surface 72 of tooth portion 7 and inner wall surface 62 of yoke portion 6), particularly in the process of accommodating coil 9 in slot 8 and forming resin sealing portion 65, is ensured.

[0023] The thickness of the resin layer 50 is, for example, 50 μm or more and 500 μm or less. The lower limit of the thickness is preferably 100 μm or more, more preferably 150 μm or more. The upper limit of the thickness is preferably 400 μm or less, more preferably 300 μm or less. The tooth inner surface resin layer 51, the tooth outer surface resin layer 52, and the yoke inner surface resin layer 53 may have the same or different thicknesses. The lower limit of the thickness is preferably within the above range from the viewpoint of ensuring the fluidity of the resin composition in the extremely narrow portion between the mold (mold core) and the wall surface of the slot 8 relative to the axial length of the stator (i.e., the thickness of the stator 4) during insert molding. The upper limit of the thickness is preferably within the above range from the viewpoint of improving the space utilization efficiency within the slot 8 in a structure in which the coil 9 is wound around the tooth portion 7 and placed in the slot 8, and ensuring the flexibility of the size of the usable coil 9 and performance such as magnetic flux density.

[0024] <Resin Layer Material> The resin material used for the resin layer 50 can be the same as that described below as the resin material for the resin sealing portion 65 .

[0025] <Resin Sealing Portion> The resin sealing portion 65 is provided on the inner periphery side of the slot 8 and seals the coil 9. The resin sealing portion 65 is provided by insert molding.

[0026] <Material of Resin Sealing Portion> The resin composition of the resin sealing portion 65 preferably contains a thermosetting resin (A), a filler (B), a curing agent (C), and the like.

[0027] [Thermosetting resin (A)] Examples of the thermosetting resin (A) include epoxy resins, cyanate resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, silicone resins, bismaleimide resins, phenoxy resins, and acrylic resins. As the thermosetting resin (A), one of these may be used alone, or two or more may be used in combination. Among these, from the viewpoint of having high insulating properties, epoxy resins, phenolic resins, and phenoxy resins are preferred as the thermosetting resin (A). From the viewpoint of ensuring flow in extremely narrow parts during molding, epoxy resins are particularly preferred.

[0028] Examples of epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin (4,4'-(1,3-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene)bisphenol type epoxy resin), and bisphenol Z type epoxy resin (4,4'-cyclohexidienebisphenol type epoxy resin); phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol group methane type novolac type epoxy resin, tetraphenol group ethoxylated epoxy resin, and the like. Examples of the epoxy resin include novolac-type epoxy resins such as benzophenone-type novolac-type epoxy resins and novolac-type epoxy resins having a condensed ring aromatic hydrocarbon structure; biphenyl-type epoxy resins; aryl alkylene-type epoxy resins such as xylylene-type epoxy resins and biphenyl aralkyl-type epoxy resins; naphthalene-type epoxy resins such as naphthylene ether-type epoxy resins, naphthol-type epoxy resins, naphthalene diol-type epoxy resins, bifunctional to tetrafunctional epoxy naphthalene resins, binaphthyl-type epoxy resins, and naphthalene aralkyl-type epoxy resins; anthracene-type epoxy resins; phenoxy-type epoxy resins; dicyclopentadiene-type epoxy resins; norbornene-type epoxy resins; adamantane-type epoxy resins; and fluorene-type epoxy resins. These may be used singly or in combination of two or more.

[0029] Among the epoxy resins, from the viewpoint of further improving heat resistance and insulation reliability, it is preferable to use one or more types selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, biphenyl-type epoxy resins, aryl alkylene-type epoxy resins, naphthalene-type epoxy resins, anthracene-type epoxy resins, and dicyclopentadiene-type epoxy resins.

[0030] Examples of phenolic resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, and resol-type phenolic resins. One of these may be used alone, or two or more may be used in combination. Among phenolic resins, phenol novolac resins are preferred.

[0031] The content of the thermosetting resin (A) is preferably 1% by mass or more, and more preferably 3% by mass or more, relative to the total amount of the resin composition of the resin sealing portion 65. The content is preferably 10% by mass or less, and more preferably 5% by mass or less, relative to the total amount of the resin composition of the resin sealing portion 65.

[0032] When the content of the thermosetting resin (A) is equal to or greater than the lower limit, the handleability of the entire resin composition of the resin sealing portion 65 is improved, making it easier to form the resin sealing portion 65 and improving the strength of the resin sealing portion 65.

[0033] When the content of the thermosetting resin (A) is equal to or less than the upper limit, the linear expansion coefficient and elastic modulus of the resin sealing portion 65 are further improved, and the thermal conductivity is further improved.

[0034] [Filler (B)] The filler (B) in this embodiment is used from the viewpoint of improving the thermal conductivity of the resin sealing portion 65 and obtaining strength.

[0035] As the filler (B), an inorganic filler is preferred, and a thermally conductive filler is particularly preferred. More specifically, as the filler (B), from the viewpoint of achieving a balance between thermal conductivity and electrical insulation, for example, silica, alumina, boron nitride, aluminum nitride, silicon carbide, etc. may be mentioned. These may be used alone or in combination of two or more. Among them, it is preferable that the filler (B) contains at least one selected from the group consisting of alumina and silica (fused silica, crystalline silica).

[0036] The content of filler (B), i.e., the content of the inorganic filler, is 90% by mass or more and 93% by mass or less with respect to the total amount of the resin composition (the entire thermosetting resin composition). By setting the content of the inorganic filler within the above range, the fluidity and filling property of the resin composition during molding can be more effectively improved. More specifically, from the viewpoint of achieving the thermal conductivity described below, the lower limit is preferably 90% by mass or more. On the other hand, from the viewpoint of fluidity and filling property, it is preferably 93% by mass or less.

[0037] The inorganic filler preferably contains 60 mass % or more of alumina relative to the entire thermosetting resin composition, more preferably 65 mass % or more, and even more preferably 70 mass % or more, which can increase the thermal conductivity of the resin sealing portion 65 (i.e., the cured product of the thermosetting resin composition).

[0038] [Curing Agent (C)] When an epoxy resin or a phenolic resin is used as the thermosetting resin (A), the resin composition preferably further contains a curing agent (C). As the curing agent (C), one or more selected from a curing catalyst (C-1) and a phenolic curing agent (C-2) can be used.

[0039] Examples of the curing catalyst (C-1) include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, bisacetylacetonate cobalt(II), and trisacetylacetonate cobalt(III); tertiary amines such as triethylamine, tributylamine, and 1,4-diazabicyclo[2.2.2]octane; 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, and 2-phenyl-4-methyl-5-hydroxyimidazole; imidazoles such as 2-phenyl-4,5-dihydroxymethylimidazole; organic phosphorus compounds such as triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine triphenylborane, 1,2-bis-(diphenylphosphino)ethane; phenolic compounds such as phenol, bisphenol A, nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid, p-toluenesulfonic acid; etc., or mixtures thereof. As the curing catalyst (C-1), one of these, including derivatives thereof, can be used alone, or two or more of these, including derivatives thereof, can be used in combination.

[0040] The content of the curing catalyst (C-1) is not particularly limited, but is preferably 0.001% by mass or more and 1% by mass or less based on the total amount of the resin composition.

[0041] Examples of the phenolic curing agent (C-2) include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, trisphenolmethane-type novolac resin, naphthol novolac resin, and aminotriazine novolac resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F; and resol-type phenolic resins, and these may be used alone or in combination of two or more.

[0042] Among these, from the viewpoint of improving the glass transition temperature and reducing the linear expansion coefficient, the phenolic curing agent (C-2) is preferably a novolac phenolic resin or a resol phenolic resin. The content of the phenolic curing agent (C-2) is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, relative to the total amount of the resin composition. Furthermore, the content is preferably 10% by mass or less, more preferably 5% by mass or less, relative to the total amount of the resin composition.

[0043] [Coupling Agent (D)] The resin composition may contain a coupling agent (D). The coupling agent (D) can improve the wettability at the interface between the thermosetting resin (A) and the filler (B).

[0044] The coupling agent (D) is not particularly limited, but it is preferable to use, for example, one or more coupling agents selected from epoxy silane coupling agents, cationic silane coupling agents, amino silane coupling agents, titanate-based coupling agents, and silicone oil-type coupling agents.

[0045] The content of the coupling agent (D) is not particularly limited, but is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to 100% by mass of the filler (B), and is preferably 3% by mass or less, more preferably 2% by mass or less, relative to 100% by mass of the filler (B).

[0046] [Phenoxy Resin (E)] The resin composition may further contain a phenoxy resin (E). The inclusion of the phenoxy resin (E) can improve the bending resistance of the resin-sealed portion 65 and reduce the elastic modulus, thereby improving the stress relaxation force of the resin-sealed portion 65.

[0047] Furthermore, when the phenoxy resin (E) is contained, the viscosity increases, which reduces the fluidity and prevents the occurrence of voids, etc. Furthermore, when the resin sealing portion 65 is used in close contact with a metal member, the adhesion between the metal and the cured product of the resin composition can be improved.

[0048] Examples of the phenoxy resin (E) include phenoxy resins having a bisphenol skeleton, phenoxy resins having a naphthalene skeleton, phenoxy resins having an anthracene skeleton, and phenoxy resins having a biphenyl skeleton. Phenoxy resins having a structure containing multiple types of these skeletons can also be used. The content of the phenoxy resin (E) is preferably, for example, 2% by mass or more and 5% by mass or less based on the total amount of the resin composition.

[0049] [Wax (mold release agent)] The resin composition contains a wax. This can improve the releasability from the mold core 80 after molding. Examples of waxes include natural waxes such as carnauba wax, synthetic waxes such as Montan acid ester wax and oxidized polyethylene wax, higher fatty acids such as zinc stearate and their metal salts, and paraffin. These may be used alone or in combination of two or more. In particular, it is preferable to contain Montan acid ester wax.

[0050] When wax (mold release agent) is used, its content in the entire resin molding material is preferably 0.01 to 0.3 mass %, more preferably 0.02 to 0.1 mass %, which can reliably improve the mold releasability, thereby improving the molding precision of the resin sealing portion 65.

[0051] [Other Components] The resin composition may also contain other components such as an adhesion promoter, a stress reducing agent, a colorant, etc., within the scope of not impairing the effects of the present invention.

[0052] <Particle size distribution of inorganic filler> In the particle size distribution of the inorganic filler, D90 is 40 μm or more and 70 μm or less, and D10 is 0.1 μm or more and 1.0 μm or less. D90 and D10 are particle sizes of the inorganic filler at which the cumulative frequency measured using, for example, a laser diffraction particle size distribution analyzer is 90% and 10%, respectively, and are measured on a volume basis in this embodiment. The particle size distribution of the inorganic filler can be determined by the ash content of the resin composition.

[0053] D10 can be said to be an index indicating the proportion of fine powder; the smaller the D10, the higher the proportion of fine powder, and the better the filling ability in narrow spaces such as gaps between coils. The lower limit of D10 is preferably 0.05 μm or more, more preferably 0.1 μm or more. The upper limit of D10 is preferably 0.9 μm or less, more preferably 0.8 μm or less. If D10 is too small, i.e., if there is too much fine filler, this is preferable from the perspective of narrow space filling ability, but on the other hand, thixotropy increases, the melt viscosity increases, and fluidity tends to deteriorate. If D10 is too large, i.e., if there is too little fine filler, the melt viscosity of the resin decreases, but the filling ability in narrow spaces tends to deteriorate. Therefore, by setting D10 within the above range, it is possible to achieve a balance between narrow space filling ability, fluidity, and melt viscosity.

[0054] D90 can be said to be an index showing the proportion of coarse powder; the larger the D90, the smaller the proportion of coarse powder and the better the narrow-section filling ability. The lower limit of D90 is preferably 45 μm or more, more preferably 50 μm or more. The upper limit of D90 is preferably 65 μm or less, more preferably 60 μm or less. If D90 is too small, i.e., if the amount of coarse powder is too small, it is preferable from the viewpoint of narrow-section filling ability, but on the other hand, thixotropy increases, the melt viscosity increases, and fluidity tends to deteriorate. If D90 is too large, i.e., if the amount of coarse powder is too large, the melt viscosity of the resin decreases, but the narrow-section filling ability tends to deteriorate. Therefore, by setting D90 within the above range, it is possible to achieve a balance between narrow-section filling ability, fluidity, and melt viscosity.

[0055] In this way, by understanding the particle size distribution of the inorganic filler using two indices, D10 and D90, it is possible to understand the ratio of fine powder to coarse powder in the inorganic filler, thereby achieving both flowability and narrow-area filling ability.

[0056] The ratio D90 / D10 of D90 to D10 in the particle size distribution is 100 or more and 300 or less. The lower limit of the ratio D90 / D10 is preferably 125 or more, more preferably 150 or more. The upper limit is preferably 275 or less, more preferably 250 or less. By setting the ratio D90 / D10 within this range, good fluidity and narrow-section filling ability can be achieved. More specifically, if D90 / 10 is too large, i.e., if the amount of coarse powder is too small, the narrow-section filling ability will be good, but on the other hand, thixotropy will increase, the melt viscosity will increase, and the fluidity will tend to deteriorate. If D90 / 10 is too small, i.e., if the amount of coarse powder is too large, the melt viscosity of the resin will decrease, but the narrow-section filling ability will tend to deteriorate. Therefore, by setting D90 / 10 within the above range, it is possible to achieve a balance between narrow-section filling ability, fluidity, and melt viscosity.

[0057] The ratio D90 / D50 of the particle size distribution D90 to D50 is 4 or more and 8 or less. The larger the ratio D90 / D50, the smaller the proportion of coarse powder and the better the filling ability. In particular, increasing the occupancy rate of the coil 9 narrows the space in which the resin sealing portion 65 is provided (i.e., the space between the coil 9 and the wall surface of the slot 8), but even under such conditions, high filling ability can be achieved. The lower limit of the ratio D90 / D50 is preferably 4.5 or more, more preferably 5 or more. The upper limit is preferably 7.5 or less, more preferably 7 or less. If D90 / 50 is too large, i.e., if the amount of coarse powder is too small, this is preferable from the perspective of narrow portion filling ability, but on the other hand, thixotropy increases, the melt viscosity increases, and fluidity tends to deteriorate. On the other hand, if D90 / 50 is too small, i.e., if the amount of coarse powder is too large, the melt viscosity of the resin decreases, but the filling ability of narrow portions tends to deteriorate. Therefore, by setting D90 / 50 within the above range, it is possible to achieve a good balance between the narrow-section filling ability, flowability, and melt viscosity.

[0058] <Physical Properties of Resin Sealing Portion> The physical properties of the cured resin material that forms the resin sealing portion 65 are, for example, as follows: The physical properties of the cured resin material that forms the resin layer 50 can be similarly set.

[0059] <Thermal Conductivity> The thermal conductivity of the cured resin material of the resin sealing portion 65 is 3.2 W / mK or more. The lower limit of the thermal conductivity is preferably 4.0 W / mK or more, and more preferably 5.0 W / mK or more. The upper limit of the thermal conductivity is not particularly limited, but a realistic value is 15 W / mK. The desired thermal conductivity can be obtained by adjusting the content of the inorganic filler. By keeping the thermal conductivity within the above range, the heat of the coil 9 can be effectively transferred to the stator core 41.

[0060] <Glass Transition Temperature Tg> The glass transition temperature Tg of the cured product of the resin sealing portion 65 is 175°C or higher, preferably 190°C or higher, and more preferably 200°C or higher. The glass transition temperature Tg of the cured product is measured using a thermomechanical analyzer (TMA) under conditions of, for example, a measurement temperature range of 0°C to 320°C and a temperature increase rate of 5°C / min. By setting the glass transition temperature Tg within the above range, the motor 100 can be used at high temperatures and is resistant to heat generation in the coil 9, allowing it to be used at high output. In particular, the operating temperature tends to increase as the output of the stator 4 increases. As described above, increasing the thermal conductivity of the resin sealing portion 65 allows heat generated in the coil 9 to be efficiently conducted to and dissipated by the stator core 41. Furthermore, setting the glass transition temperature Tg within the above range increases the heat resistance of the resin, thereby increasing design flexibility and margin.

[0061] <Gel time> The gel time is 40 seconds or more and 100 seconds or less. From the viewpoint of improving the moldability of the resin composition and shortening the molding cycle, the gel time of the resin composition is preferably 45 seconds or more, more preferably 50 seconds or more. From the viewpoint of realizing a cured product with excellent curing properties, the gel time of the resin composition is preferably 100 seconds or less, more preferably 75 seconds or less. The gel time can be measured by melting the resin composition on a hot plate heated to 175°C, and then measuring the time (gel time) until the composition becomes tack-free while kneading with a spatula.

[0062] <Minimum Melt Viscosity> The minimum melt viscosity is 1.0 Pa·s or more and 100.0 Pa·s or less. The minimum melt viscosity can be controlled by adjusting the type of thermosetting resin used and the amount of thermoplastic resin blended. The lower limit of the minimum melt viscosity of the cured product of the resin composition of the resin sealing portion 65 is, for example, 1.0 Pa·s or more. If the above value is exceeded, the filling ability may decrease, and voids or unfilled portions may occur.

[0063] The minimum melt viscosity of the cured resin composition of the resin sealing portion 65 refers to the minimum viscosity exhibited by the phenolic resin composition when the cured resin is melted by heating. More specifically, when the resin sealing portion 65 is heated at a constant temperature increase rate to melt the resin, the melt viscosity decreases with increasing temperature in the initial stage, and then increases with increasing temperature once the temperature exceeds a certain level. The minimum melt viscosity refers to the melt viscosity at such a minimum point. The minimum melt viscosity of the resin composition layer can be measured by a dynamic viscoelasticity method.

[0064] The minimum melt viscosity varies depending on the size of the stator 4 (stator core 41). In the case of a small stator 4, the volume of the resin sealing portion 65 is small, and generally, a low viscosity is preferable in consideration of the ability to fill narrow areas. In the case of a large stator 4, the volume of the resin sealing portion 65 is large, and if the viscosity is low, there is a tendency for entrapment voids to increase, and the voids may not be completely crushed by the holding pressure, so the viscosity is adjusted to a certain degree.

[0065] <Method for producing resin composition> Next, a method for producing a resin composition will be described. For example, first, the above-mentioned raw material components are mixed by known means to obtain a mixture. Then, the mixture is melt-kneaded to obtain a kneaded product. As a kneading method, for example, an extrusion kneader such as a single-screw kneading extruder or a twin-screw kneading extruder, or a roll kneader such as a mixing roll can be used, but it is preferable to use a twin-screw kneading extruder. After cooling, the kneaded product can be formed into a desired shape such as powder, granules, tablets, or sheets.

[0066] A method for obtaining a powdery resin composition includes, for example, pulverizing the kneaded material using a pulverizer. The kneaded material may be formed into a sheet and then pulverized. Examples of the pulverizer that can be used include a hammer mill, a stone mill, and a roll crusher.

[0067] As a method for obtaining a granular or powdery resin composition, for example, a granulation method typified by a hot-cut method can be used, in which a die having a small diameter is provided at the outlet of a kneading device and the molten kneaded product discharged from the die is cut to a predetermined length with a cutter, etc. In this case, after obtaining a granular or powdery resin composition by a granulation method such as the hot-cut method, it is preferable to degas the resin composition before the temperature of the resin composition drops significantly.

[0068] The resin composition obtained in this embodiment contains an epoxy resin, a curing agent, and an inorganic filler, and the content of the inorganic filler, the glass transition temperature of the cured product, and the hot elastic modulus of the cured product are all within the specific ranges described above. Therefore, the resin composition is suitably used as a resin sealing portion 65 to be used when sealing the coil 9 in the slot 8, and a resin sealing portion 65 can be obtained that has excellent workability when filling the resin composition, excellent resin filling properties, and excellent thermal history resistance of the cured product.

[0069] Summary of the Embodiment The features of the present embodiment can be summarized as follows. <1> A thermosetting resin composition used to form a sealing member (resin sealing portion 65) in a stator 4 including a stator core 41 having a plurality of teeth 7 and a plurality of slots 8 arranged alternately in the circumferential direction, a coil 9 wound around and housed in the slots 8, and a sealing member (resin sealing portion 65) provided in the slots 8 to seal the coil 9, the thermosetting resin composition comprising: an epoxy resin; a curing agent; and an inorganic filler, the inorganic filler having a particle size distribution in which D90 is 40 μm or more and 70 μm or less and D10 is 0.1 μm or more and 1.0 μm or less. <2> The thermosetting resin composition according to <1>, wherein the ratio D90 / D10 of the D90 to the D10 in the particle size distribution is 100 or more and 300 or less. <3> The thermosetting resin composition according to <1> or <2>, wherein the ratio D90 to D50 in the particle size distribution, D90 / D50, is 4 or more and 8 or less. <4> The thermosetting resin composition according to any one of <1> to <3>, wherein the content of the inorganic filler is 90% by mass or more and 93% by mass or less, based on the total mass of the thermosetting resin composition. <5> The thermosetting resin composition according to any one of <1> to <4>, wherein the inorganic filler includes at least one selected from the group consisting of alumina, fused silica, and crystalline silica. <6> The thermosetting resin composition according to <5>, wherein the inorganic filler includes 60% by mass or more of alumina, based on the total mass of the thermosetting resin composition. <7> The thermosetting resin composition according to any one of <1> to <6>, wherein the gel time is 40 seconds or more and 100 seconds or less. <8> The thermosetting resin composition according to any one of <1> to <7>, wherein the cured product of the thermosetting resin composition has a thermal conductivity of 3.2 W / mK or more. <9> The thermosetting resin composition according to any one of <1> to <8>, wherein the epoxy resin comprises at least one selected from the group consisting of biphenyl-type epoxy resins, bisphenol-type epoxy resins, stilbene-type epoxy resins, novolac-type epoxy resins, multifunctional epoxy resins, phenol aralkyl-type epoxy resins, and naphthol-type epoxy resins.<10> The thermosetting resin composition according to any one of <1> to <9>, having a glass transition point of 175° C. or higher. <11> A stator (4) having: a stator core (41) having a plurality of teeth (7) and a plurality of slots (8) formed alternately in the circumferential direction; a coil (9) wound around and housed in the slots (8); and a sealing member (resin sealing portion (65)) provided within the slots (8) to seal the coil (9), wherein the sealing member (resin sealing portion (65)) is made of a cured product of the thermosetting resin composition according to any one of <1> to <10>.

[0070] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0071] The present invention will be described in detail below using examples, but the present invention is not limited to the descriptions of these examples.

[0072] The raw material components used in each example and comparative example are as follows: (Epoxy resin) Epoxy resin 1: Biphenyl type epoxy resin (YL-6677, manufactured by Mitsubishi Chemical Corporation) Epoxy resin 2: Biphenyl type epoxy resin (YX-4000HK, manufactured by Mitsubishi Chemical Corporation)

[0073] (Hardening agent) ・Hardening agent 1: Novolac type phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-55617) ・Hardening agent 2: Triphenolmethane type phenolic resin (manufactured by Meiwa Kasei Co., Ltd., MEH-7500)

[0074] (Inorganic fillers) Inorganic filler 1: Alumina 1 (fused spherical alumina (D50: 20 μm, circularity 0.92 or more)) Inorganic filler 2: Alumina 2 (fused spherical alumina (D50: 16.7 μm, circularity 0.92 or more)) Inorganic filler 3: Alumina 3 (fine powder alumina (D50: 0.7 μm)) Inorganic filler 4: Silica 1 (fused spherical alumina (D50: 10.8 μm, circularity 0.92 or more)) Inorganic filler 4: Silica 2 (fused spherical alumina (D50: 0.5 μm, circularity 0.92 or more))

[0075] (Curing accelerators) Curing accelerator 1: tetraphenylphosphonium 2,3-dihydroxynaphthalate Curing accelerator 2: tetraphenylphosphonium 4,4'-sulfonyldiphenolate

[0076] (Other additives) Mold release agent: carnauba wax (TOWAX-132, manufactured by Toa Kasei Co., Ltd.) Coupling agent: N-phenyl-3-aminopropyltrimethoxysilane (CF-4083, manufactured by Toray Dow Corning Co., Ltd.) Stress reducing agent: low stress material (FZ-3730, manufactured by Toray Dow Corning Co., Ltd.) Colorant 1: carbon black (Carbon #5, manufactured by Mitsubishi Chemical Corporation)

[0077] (Preparation of Resin Composition) First, the raw materials formulated according to Table 1 were mixed at room temperature using a mixer, and then roll-kneaded at 70° C. or higher and 110° C. or lower. Next, the resulting kneaded mixture was cooled and then pulverized to obtain a resin composition.

[0078] The resin compositions obtained in the examples were subjected to the following measurements. The measurement results are shown in Table 1.

[0079] (Gel time) The gel time of the encapsulating resin composition obtained in each example was measured by melting the encapsulating resin composition on a hot plate heated to 175°C, and then measuring the time (gel time: seconds) until the composition hardened while kneading with a spatula.

[0080] (Glass Transition Temperature Tg) For each example, the glass transition temperature Tg of the cured product of the obtained resin composition was measured as follows. First, the encapsulating resin composition was injection molded using a transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a 15 mm x 4 mm x 4 mm test piece. Next, the obtained test piece was post-cured at 175°C for 4 hours, and then measured using a thermomechanical analyzer (Seiko Instruments Inc., TMA100) under conditions of a measurement temperature range of 40°C to 300°C and a heating rate of 5°C / min. The glass transition temperature was calculated from the measurement results.

[0081] (Thermal Conductivity) The resin composition obtained in each example was injection molded into an encapsulating resin composition using a transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a cured product of 10 mm x 10 mm x 1 mm. The thermal conductivity of the obtained cured product was calculated using the following formula from the thermal diffusion coefficient (α) measured by the laser flash method (half-time method), the specific heat (Cp) measured by the DSC method, and the density (ρ) measured in accordance with JIS K 6911. The unit of thermal conductivity is W / m K. Thermal conductivity [W / m K] = α [mm ２ / s]×Cp[J / kg・K]×ρ[g / cm ３ ]

[0082] (Particle size distribution) The particle size distribution (D10, D50, D90) of each inorganic filler was measured using a laser particle size analyzer (SALD-7000, manufactured by Shimadzu Corporation). Based on the measurement results, the ratios D90 / 10 and D90 / D50 were calculated.

[0083]

[0084] This application claims priority based on Japanese Patent Application No. 2023-213558, filed December 19, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0085] REFERENCE SIGNS LIST 1 Case 2 Rotor 4 Stator 5 Permanent magnet 6 Yoke portion 7 Teeth portion 8 Slot 9 Coil 21 Coil accommodating portion 41 Stator core 50 Resin layer 62, 72 Inner wall surface 65 Resin sealing portion 100 Motor

Claims

1. A thermosetting resin composition used to form a sealing member in a stator having a stator core having a plurality of teeth and a plurality of slots formed alternately in the circumferential direction, a coil wound around and housed in the slot, and a sealing member provided within the slot to seal the coil, the thermosetting resin composition comprising an epoxy resin, a curing agent, and an inorganic filler, the inorganic filler having a particle size distribution in which D90 is 40 μm or more and 70 μm or less, and D10 is 0.1 μm or more and 1.0 μm or less.

2. The thermosetting resin composition according to claim 1, wherein the ratio D90 / D10 of the D90 to the D10 in the particle size distribution is 100 or more and 300 or less.

3. The thermosetting resin composition according to claim 1 or 2, wherein the ratio D90 / D50 of the D90 to D50 in the particle size distribution is 4 or more and 8 or less.

4. The thermosetting resin composition according to claim 1 or 2, wherein the content of the inorganic filler is 90% by mass or more and 93% by mass or less based on the entire thermosetting resin composition.

5. The thermosetting resin composition according to claim 1 or 2, wherein the inorganic filler comprises at least one selected from the group consisting of alumina, fused silica, and crystalline silica.

6. The thermosetting resin composition according to claim 5, wherein the inorganic filler contains 60 mass% or more of alumina based on the entire thermosetting resin composition.

7. The thermosetting resin composition according to claim 1 or 2, having a gel time of 40 seconds or more and 100 seconds or less.

8. The thermosetting resin composition according to claim 1 or 2, wherein the cured product of the thermosetting resin composition has a thermal conductivity of 3.2 W / mK or more.

9. The thermosetting resin composition according to claim 1 or 2, wherein the epoxy resin comprises at least one selected from the group consisting of biphenyl-type epoxy resins, bisphenol-type epoxy resins, stilbene-type epoxy resins, novolac-type epoxy resins, multifunctional epoxy resins, phenol aralkyl-type epoxy resins, and naphthol-type epoxy resins.

10. The thermosetting resin composition according to claim 1 or 2, having a glass transition point of 175°C or higher.

11. A stator having a stator core having a plurality of teeth and a plurality of slots formed alternately in the circumferential direction, a coil wound around and housed in said slot, and a sealing member provided within said slot to seal said coil, wherein said sealing member is made of a cured product of the thermosetting resin composition according to claim 1 or 2.

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