Semiconductive member, stator coil, and rotating electrical machine

Abstract

A semiconductive member according to one embodiment of the present disclosure comprises: semiconductive resin layers that are disposed on a fibrous insulating substrate, and that contains silica particles, conductive particles, and silsesquioxane in thermosetting resin. The silica particles are unevenly distributed on the surface of the semiconductive resin layers.

Description

Semiconducting member, stator coil, and rotating electrical machine

[0001] The present disclosure relates to a semiconducting member, a stator coil, and a rotating electrical machine. This application claims priority based on Japanese Patent Application No. 2024-197300 filed in Japan on November 12, 2024, and incorporates its content herein by reference.

[0002] In a stator coil used in a stator of a high-output rotating electrical machine, in order to suppress corona discharge generated in the minute space between the iron core and the main insulation layer, a semiconducting layer in which a semiconducting tape is wound around the outer layer of the main insulation layer covering the conductor portion formed by bundling strand conductors is arranged. This semiconducting tape plays a role of reducing the voltage shared in the minute space on the surface of the iron core by relaxing the potential gradient between the iron core and the main insulation layer. The above semiconducting tape is manufactured by disposing a semiconducting resin layer in which conductive particles such as carbon black are added to a resin on a fibrous insulating base material such as glass cloth or non-woven fabric.

[0003] In recent years, with the further miniaturization and higher output of rotating electrical machines, electrical, thermal, and mechanical stresses during operation tend to increase, so the semiconducting layer deteriorates over time. Also, since it is difficult to manufacture the interface between the main insulation layer and the semiconducting layer completely void-free, partial discharges that are correspondingly high occur starting from the voids, accelerating the deterioration of the semiconducting layer, and making it difficult to suppress corona discharge generated in the space between the iron core and the main insulation layer in the long term.

[0004] Therefore, a semiconducting tape in which a semiconducting resin layer containing at least one inorganic particle selected from layered viscosity mineral-based particles, oxide-based particles, and nitride-based particles in addition to conductive particles is applied to a fibrous insulating base material is disclosed (see, for example, Patent Document 1). Also, a semiconductor tape in which a mixture containing non-conductive nanoparticles added to a polymer is disposed on a fibrous insulating base material is disclosed (see, for example, Patent Document 2).

[0005] Japanese Patent Application Laid-Open No. 2006-246599 International Publication No. 2018 / 002974

[0006] The degradation caused by partial discharge can be broadly classified into three components: the impact effect of charged particles, the thermal decomposition effect due to localized temperature rise, and the chemical reaction caused by the activated gas generated by the discharge. These components work synergistically to accelerate the degradation. In this case, the inventor focused on the ozone (O) generated by the discharge, among these components. ３ We have newly discovered that the oxidative effect of activated gases such as ozone and atomic oxygen (O) is extremely significant and is the dominant factor in the degradation of the semiconducting layer. Therefore, in this respect, although the semiconducting tapes disclosed in the above-mentioned patent documents can be expected to show improved initial corona resistance, the organic resins and polymers degrade rapidly due to the oxidative effect of ozone and atomic oxygen generated by the partial discharge described above. As a result, the semiconducting tapes disclosed in the above-mentioned patent documents have the problem that it is difficult to maintain initial corona resistance over the long term because they decompose into low-molecular-weight volatile products.

[0007] This disclosure has been made in view of the above-mentioned problems and aims to provide a semiconducting member, a stator coil, and a rotating electric machine that can exhibit stable corona resistance over a long period of time.

[0008] One embodiment of the semiconducting member of the present disclosure comprises a semiconducting resin layer disposed on a fibrous insulating substrate, the semiconducting resin layer containing silica particles, conductive particles, and silsesquioxane within a thermosetting resin, wherein the silica particles are unevenly distributed on the surface of the semiconducting resin layer.

[0009] One embodiment of the stator coil of the present disclosure comprises a winding comprising a conductor portion formed by bundling strands of conductors, an insulating layer wound around the outer circumference of the conductor portion, and a semiconducting layer in which the above-mentioned semiconducting member is wound around the outer circumference of the insulating layer, and the thermosetting resin impregnated into the winding.

[0010] One embodiment of the rotating electric machine of this disclosure comprises the stator coil described above.

[0011] According to this disclosure, it is possible to provide semiconducting members, stator coils, and rotating electric machines that exhibit stable corona resistance over a long period of time.

[0012] A schematic cross-sectional diagram showing the configuration of a semiconducting tape according to Embodiment 1 of this disclosure. A schematic cross-sectional diagram showing the configuration of a stator coil and a rotating electric machine according to Embodiment 2 of this disclosure. A schematic cross-sectional diagram showing the configuration of a semiconducting tape according to Embodiment 3 of this disclosure. A schematic cross-sectional diagram showing the distribution of silica particles inside the semiconducting tape according to Embodiment 1. A flowchart showing the manufacturing process of the semiconducting tape according to the embodiment.

[0013] The semiconductive member, stator coil, and rotating electric machine according to embodiments of this disclosure will be described below with reference to the drawings. The scope of this disclosure is not limited to the embodiments described below, and can be arbitrarily modified within the scope of the technical concept of this disclosure. Furthermore, in the following drawings, the scale and number of components in each structure may differ from those in the actual structure in order to make the components easier to understand.

[0014] (Embodiment 1) Figure 1 is a schematic cross-sectional view showing the configuration of the semiconductive tape 1 according to Embodiment 1. As shown in Figure 1, the semiconductive tape 1, as a semiconductive member, comprises a fibrous insulating base material 6 and semiconductive resin layers 11a and 11b. The semiconductive resin layers 11a and 11b are held on both sides of the fibrous insulating base material 6, respectively.

[0015] The semiconductive resin layer 11a has silica particles 2, conductive particles 3, and silsesquioxane 4 dispersed and mixed within the thermosetting resin 5a. The semiconductive resin layer 11b has silica particles 2, conductive particles 3, and silsesquioxane 4 dispersed and mixed within the thermosetting resin 5b.

[0016] In the following explanation, thermosetting resin 5a and thermosetting resin 5b may be collectively referred to as thermosetting resin 5. Also, semiconductive resin layer 11a and semiconductive resin layer 11b may be collectively referred to as semiconductive resin layer 11.

[0017] The silica particles 2 are locally unevenly distributed in the semiconductive resin layer 11a on the surface 12b opposite to the retaining surface 12a that is held by the fibrous insulating substrate 6. Similarly, the silica particles 2 are locally unevenly distributed in the semiconductive resin layer 11b on the surface 13b opposite to the retaining surface 13a that is held by the fibrous insulating substrate 6.

[0018] In the semiconductive tape 1 of Embodiment 1, the silica particles 2 are locally unevenly distributed on the surfaces 12b and 13b of the semiconductive resin layers 11a and 11b, respectively. Therefore, when activating gases such as ozone (O3) and atomic oxygen (O) are generated due to partial discharge, the silica particles 2 locally unevenly distributed on the surfaces 12b and 13b (surface layer) function as a protective layer. As a result, if voids occur in the thermosetting resins 5a and 5b, the oxidative decomposition of the thermosetting resins 5a and 5b near the voids is suppressed, and the initial corona resistance can be maintained over the long term.

[0019] (Embodiment 2) The following will mainly describe the differences from the embodiment described above, with reference to the drawings. Figure 2 is a schematic cross-sectional view showing the configuration of the stator coil and rotating electric machine according to Embodiment 2.

[0020] In the following descriptions of other embodiments, components similar to those in Embodiment 1 described above may be omitted from the description by appropriately assigning the same reference numerals.

[0021] As shown in Figure 2, the stator coil 7 is composed of a winding 20 having a conductor portion 8, a main insulating layer (insulating layer) 9, and a semiconducting layer 10. The conductor portion 8 is formed by bundling individual conductor wires 8a. The main insulating layer 9 is formed by winding mica tape around the outer circumference of the conductor portion 8. The semiconducting layer 10 is formed by winding semiconducting tape 1.

[0022] The stator coil 7 is manufactured by pressure impregnating the winding 20 with an electrical insulating varnish and then subjecting it to a heat-curing treatment. The stator coil 7 constitutes a rotating electric machine 30 such as a motor. Furthermore, the application examples of the semiconductive tape 1 of this disclosure are not limited to the semiconductive layer of the stator coil in the stator of the rotating electric machine 30 described above, but can be used in various applications such as generator coils, circuit breaker rods, and cable covering materials.

[0023] According to the stator coil and rotating electric machine in Embodiment 1, if voids occur in the thermosetting resins 5a and 5b, the oxidative decomposition of the thermosetting resins 5a and 5b near the voids can be suppressed, thereby maintaining the initial corona resistance over a long period of time.

[0024] (Embodiment 3) Figure 3 is a schematic cross-sectional view showing the semiconducting tape 1 according to Embodiment 3. Figure 3 is an enlarged view of region A in Figure 2.

[0025] As shown in Figure 3, the semiconductive tape 1 may have silica particles 2 locally distributed in the thermosetting resin 5b on the surface 13b side of the semiconductive resin layer 11b, which is positioned at least on the main insulating layer 9 side. The semiconductive layer 10 made of this semiconductive tape 1 deteriorates due to partial discharges that originate from voids present at the interface between the main insulating layer 9 and the semiconductive layer 10. Therefore, in the semiconductive resin layer 11b of the semiconductive tape 1 wound in contact with the main insulating layer 9, silica particles 2 are unevenly distributed on the surface 13b side, which is the interface with the main insulating layer 9.

[0026] In the third embodiment, the semiconducting tape 1 allows the silica particles 2 to function as a protective layer when a discharge occurs inside a void at the interface between the main insulating layer 9 and the semiconducting layer 10, thereby improving the corona resistance of the thermosetting resin 5b.

[0027] Figure 4 is a schematic cross-sectional view showing the distribution of silica particles inside the semiconductive tape 1 according to Embodiment 1. As shown in Figure 1, the semiconductive tape 1 described above is held by a fibrous insulating substrate 6 with the silica particles 2 locally unevenly distributed on the surfaces 12b and 13b (surface layer) within the thermosetting resin 5.

[0028] The semiconductive resin layers 11a and 11b have a first region R1 located on the surface 12b and 13b side of the center in the thickness direction, and a second region R2 located on the opposite side of the center in the thickness direction from the surface 12b and 13b side. If V1 is the volume fraction of silica particles 2 in the first region R1 and V2 is the volume fraction of silica particles 2 in the second region R2, then the relationship V1 / V2 ≥ 2 is satisfied. The uneven distribution of silica particles 2 is defined as satisfying the relationship V1 / V2 ≥ 2. For example, if 1 ≤ (V1 / V2) < 2, the interparticle distance of silica particles 2 increases when partial discharge occurs at the interface between the main insulating layer 9 and the semiconductive layer 10. As a result, it becomes difficult for the silica particles 2 to function as a protective layer, and the desired corona resistance cannot be achieved. Therefore, by satisfying the relationship V1 / V2 ≥ 2, the silica particles 2 can function as a protective layer, and the corona resistance of the thermosetting resin 5b can be improved.

[0029] In any of the above embodiments of the semiconductive tape 1, the surface resistance is preferably in the range of 100 Ω or more and 100 kΩ or less. If the surface resistance is less than 100 Ω, eddy currents will be generated on the surface of the semiconductive layer 10 during actual operation, which is undesirable. In any of the above embodiments of the semiconductive tape 1, the thickness of the tape is preferably in the range of 50 μm or more and 200 μm or less.

[0030] The following describes in detail each component constituting the semiconductive tape 1 according to the above embodiment.

[0031] <Silica Particles> Any silica particles that can be dispersed in the thermosetting resin 5 can be used as silica particles 2, and their type is not particularly limited. Examples of such silica particles include fumed silica and colloidal silica.

[0032] The average particle size (particle diameter) of the silica particles 2 is preferably 1 nm or more and 20 μm or less in median diameter (50% diameter, D50), and more preferably 10 nm or more and 10 μm or less. When the above range is defined, a method for measuring the average particle size can be, for example, a laser diffraction scattering particle size distribution device (Microtrac® MT3300). Note that if the average particle size of the silica particles 2 is smaller than 1 nm, the particles tend to aggregate due to the increased specific surface area, making it difficult to uniformly disperse them as single particles within the thermosetting resin 5. On the other hand, if the average particle size of the silica particles 2 is larger than 20 μm, the inter-particle distance increases proportionally, making it difficult for neighboring particles to function as a protective layer, and thus the desired corona resistance cannot be achieved. By setting the average particle size of the silica particles 2 to 1 nm or more and 20 μm or less, it becomes easy to uniformly disperse them as single particles, and the desired corona resistance can be achieved.

[0033] The silica particles 2 are dispersed in the thermosetting resin 5 of the semiconducting resin layer 11, and the amount of silica particles 2 blended with the thermosetting resin 5 is preferably in the range of 1 vol% or more and 50 vol% or less. If the amount of silica particles 2 blended with the thermosetting resin 5 is less than 1 vol%, the desired corona resistance cannot be achieved. On the other hand, if the amount of silica particles 2 blended with the thermosetting resin 5 exceeds 50 vol%, the initial resistance value of the semiconducting tape 1 decreases, and the thermosetting resin 5 becomes brittle, making it difficult to use the semiconducting tape 1. By blending the silica particles 2 with the thermosetting resin 5 at a rate of 1 vol% or more and 50 vol% or less, the desired corona resistance can be achieved while suppressing the brittleness of the thermosetting resin 5.

[0034] Furthermore, in order for partial discharge to occur starting from voids present at the interface between the main insulating layer 9 and the semiconductive layer 10, it is preferable that the silica particles 2 are locally concentrated near at least one side surface of the semiconductive tape 1, and that the average interparticle distance between the silica particles 2 is less than 1 μm. If the average interparticle distance between the silica particles 2 exceeds 1 μm, it becomes difficult for nearby silica particles 2 to function as a protective layer, and the desired corona resistance described above cannot be achieved. By making the average interparticle distance between the silica particles 2 concentrated on surfaces 12b and 13b less than 1 μm, the silica particles 2 can function as a protective layer, and the desired corona resistance described above can be achieved.

[0035] Furthermore, the silica particles 2 may be modified or coated with a coupling agent or surface treatment agent to improve adhesion to the thermosetting resin 5 or to improve dispersibility within the thermosetting resin 5. Examples of such coupling agents include silane coupling agents such as γ-glycidooxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacrylateoxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane, as well as titanate coupling agents and aluminum coupling agents. Examples of surface treatment agents include aluminum laurate, aluminum stearate, iron-alumina stearate, silica, zirconia, and silicone. These coupling agents or surface treatment agents can be used individually or as a mixture of two or more.

[0036] The silica particles 2 may be used with a conductive coating on their surface for the purpose of imparting conductivity. Such conductive coatings may include, for example, conductive carbon materials such as carbon black, graphite, conductive diamond, carbon fiber, and carbon nanotubes, or conductive metal oxides and metals such as indium oxide, cadmium oxide, triiron tetroxide, zinc oxide, tin oxide, and titanium oxide.

[0037] Here, if, for example, inorganic particles with corona resistance as shown in Patent Document 1 are used instead of silica particles to fill the thermosetting resin 5, an improvement in initial corona resistance can be expected due to the physical barrier effect. However, unless the leading edge of the degradation progression is concentrated and completely covered by the inorganic particles, the resin and polymer present between the inorganic particles will be oxidatively decomposed by the oxidation of ozone. Therefore, when using inorganic particles with corona resistance, it is difficult to maintain initial corona resistance over the long term. In addition, because electrically insulating inorganic particles are added to the semiconducting resin layer, the initial resistance value of the semiconducting tape decreases.

[0038] However, as shown in the embodiment, by using silica particles 2 that are locally unevenly distributed on the surfaces 12b and 13b (surface layer) of the semiconducting tape 1, the corona resistance of the thermosetting resin 5 can be improved. Furthermore, since silsesquioxane 4, which has corona resistance, is present in the thermosetting resins 5a and 5b that exist between the silica particles 2, the oxidative decomposition of the thermosetting resins 5a and 5b is suppressed. As a result, stable corona resistance can be achieved over a long period of time, and the initial resistance value of the semiconducting tape 1 can be maintained.

[0039] <Conductive Particles> Conductive particles 3 can be used alone or as a mixture of two or more types including other conductive particles. Any conductive particles can be used as appropriate, and the type is not particularly limited, but for example, conductive carbon materials such as carbon black, graphite, conductive diamond, carbon fiber, carbon nanotubes, and expanded graphite, or conductive metal oxides and metals such as indium oxide, cadmium oxide, triiron tetroxide, zinc oxide, tin oxide, and titanium oxide can be used.

[0040] Conductive particles 3 can be used alone or as a mixture of two or more types including other inorganic particles. Examples of inorganic particles are as follows: Layered clay mineral particles include at least one selected from mineral groups such as the smectite group, mica group, vermiculite group, and mica group. Examples of layered clay mineral particles belonging to the smectite group include montmorillonite, hectorite, saponite, souconite, beiderite, stevensite, and nontronite. Examples of layered clay mineral particles belonging to the mica group include chlorite, phlogopite, lepidolite, muscovite, biotite, paragonite, margalite, teniolite, and tetrasilicic mica. Examples of layered clay mineral particles belonging to the vermiculite group include trioctahedral vermiculite and dioctahedral vermiculite. Examples of layered clay mineral particles belonging to the mica group include muscovite, biotite, paragonite, levitrite, margalite, clintonite, and anandite. Among these, it is preferable to use layered clay mineral particles belonging to the smectite group from the viewpoint of dispersibility in thermosetting resin 5. These layered clay mineral particles can be used individually or as a mixture of two or more types. Examples of oxide particles include titanium oxide, silica, alumina, bismuth trioxide, cerium dioxide, cobalt monoxide, copper oxide, iron trioxide, holmium oxide, indium oxide, manganese oxide, magnesium oxide, tin oxide, yttrium oxide, and zinc oxide. Examples of nitride particles include titanium nitride, tantalum nitride, niobium nitride, molybdenum nitride, cobalt nitride, iron nitride, chromium nitride, vanadium nitride, aluminum nitride, boron nitride, and silicon nitride. These can be used individually or as a mixture of two or more types.

[0041] Furthermore, the conductive particles 3 may be modified or coated with a coupling agent or surface treatment agent to improve adhesion to the thermosetting resin 5 or to improve dispersibility within the thermosetting resin 5. Examples of such coupling agents include silane coupling agents such as γ-glycidooxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacrylateoxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane, as well as titanate coupling agents and aluminum coupling agents. Examples of surface treatment agents include aluminum laurate, aluminum stearate, iron-alumina stearate, silica, zirconia, and silicone. These coupling agents or surface treatment agents can be used individually or as a mixture of two or more.

[0042] <Silsesquioxane> Any silsesquioxane 4 synthesized by hydrolysis-polycondensation of an RSiO3 / 2 type compound (where R is a hydrogen atom, alkyl group, alkenyl group, aryl group, araalkyl group, etc., and X is a halogen, alkoxy group, etc.) can be used as appropriate, and the type is not particularly limited. Examples of silsesquioxane 4 having such properties include amorphous structures, ladder structures, cage-like (fully condensed cage) structures, or partially cleaved structures thereof (structures in which one silicon atom is missing from the cage-like structure, or structures in which part of the silicon-oxygen bond of the cage-like structure is broken). Two or more of these compounds may be used in combination depending on the application and the mechanical properties required for the resin composition.

[0043] Further, for the purpose of improving the adhesion to the thermosetting resin 5 or improving the dispersibility in the thermosetting resin 5, etc., a part of the main chain structure of the hydrocarbon group of the substituent R or a part of the hydrogen atoms may be substituted with a heteroatom other than carbon and hydrogen atoms represented by a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom, etc., or an organic functional group containing these heteroatoms. Examples of such organic functional groups include functional groups containing an oxygen atom and / or a sulfur atom, such as an ether group, an epoxy group, an ester group, a hydroxyl group, a carboxyl group, a carbonyl group, a sulfonyl group, a thiol group, a thioether group, a carboxylic acid anhydride group, etc.; functional groups containing a halogen atom; functional groups containing a nitrogen atom, such as an amino group, an ammonium base, an amide group, an imino group, an imide group, a nitrile group, a urea group, a urethane group, a pyridyl group, etc. Among these, an oxetanyl group, an acryloyl group, a methacryloyl group, an epoxy group or a thiol group is preferable from the viewpoint of dispersibility in the thermosetting resin 5, etc.

[0044] Further, for the purpose of promoting the reactivity, at least one photopolymerization initiator selected from the group consisting of a photo radical polymerization initiator, a photo cationic polymerization initiator, and a photo anionic polymerization initiator, or at least one thermal polymerization initiator selected from the group consisting of a thermal radical polymerization initiator, a thermal cationic polymerization initiator, and a thermal anionic polymerization initiator may be used for the silsesquioxane 4.

[0045] The photoradical polymerization initiator is not particularly limited, but includes acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; thioxanthone compounds such as thioxanthone, diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and 2-isopropylthioxanthone; benzoin ketals such as 2'2-dimethoxy-1,2-diphenylethane-1-one and benzyldimethyl ketal; 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, and 1-[4- Examples include α-hydroxyketones such as (2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one; α-aminoketones such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one and 1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one; oxime esters such as 1-4-(phenylthio)phenyl]-1,2-octadione-2-(benzoyl)oxime; and phosphine oxides such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. The photoradical polymerization initiator may use one of these compounds alone or in combination of two or more.

[0046] The photo cationic polymerization initiator is not particularly limited as long as it generates an acid upon irradiation with light. Examples of the photo cationic polymerization initiator include B(C6F5)4 salts, PF6 salts, AsF6 salts, SbF6 salts, CF3SO3 salts of onium compounds such as sulfonium, phosphonium, diazonium, iodonium, ammonium, and pyridinium; sulfides that generate sulfonic acid; halides that generate hydrogen halide; iron arene complexes; diphenyl[4-(phenylthio)phenyl]sulfonium hexafluoroantimonate, and the like. The photo cationic polymerization initiator may be used alone or in combination of two or more of these compounds.

[0047] The photo anionic polymerization initiator is not particularly limited, and examples thereof include acetophenone O-benzoyloxime, niflumic acid, 2-(9-oxoxanthen-2-yl)propionic acid 1,5,7-triazabicyclo[4,4,0]dec-5-ene, 2-nitrophenylmethyl 4-methacryloyloxypiperidine-1-carboxylate, 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidinium 2-(3-benzoylphenyl)propionate, 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium n-butyltriphenylborate, and the like.

[0048] The thermal radical polymerization initiator is not particularly limited as long as it generates radicals upon heating and initiates a chain polymerization reaction. Examples of the thermal radical polymerization initiator include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, and the like, and benzopinacol is preferably used. The thermal radical polymerization initiator may be used alone or in combination of two or more of these compounds.

[0049] The thermal cationic polymerization initiator is not particularly limited as long as it generates cationic species such as Brønsted acids and Lewis acids. Examples of thermal cationic polymerization initiators include sulfonium salts, phosphonium salts, quaternary ammonium salts, aryldiazonium salts, aryliodonium salts and other onium salts, organosilanes, heteropoly acids, allene-ion complexes, and boron trifluoride amine complexes. Using such thermal cationic polymerization initiators tends to improve dimensional accuracy and degree of curing. These compounds may be used individually or in combination of two or more as thermal cationic polymerization initiators.

[0050] The thermal anionic polymerization initiator is not particularly limited as long as it is a compound that generates a base capable of anionic polymerization of anionic polymerizable compounds upon heating. More specifically, as a thermal anionic polymerization initiator, aliphatic amine compounds, aromatic amine compounds, secondary or tertiary amine compounds, imidazole compounds, polymercaptan compounds, boron trifluoride-amine complexes, dicyandiamides, organic acid hydrazides, etc., can be used, and encapsulated imidazole compounds that exhibit good latent properties with respect to temperature may also be used.

[0051] The polymerization reaction initiation temperature of silsesquioxane 4 is preferably in a temperature range lower than the curing temperature of the thermosetting resin 5 to be impregnated, but higher than 100°C. If the polymerization reaction initiation temperature of silsesquioxane 4 is 100°C or lower, the polymerization reaction will start before the impregnation treatment, making the semiconductive layer 10 brittle and difficult to use as tape. On the other hand, if the polymerization reaction initiation temperature of silsesquioxane 4 is higher than the curing temperature of the thermosetting resin to be impregnated, unreacted portions of silsesquioxane 4 will remain after the curing treatment of the thermosetting resin, and the desired corona resistance cannot be achieved. By setting the polymerization reaction initiation temperature of silsesquioxane 4 to a temperature range lower than the curing temperature of the thermosetting resin 5 to be impregnated, but higher than 100°C, the brittleness of the semiconductive layer 10 is suppressed, allowing for stable use as tape and enabling the achievement of the desired corona resistance.

[0052] As described above, when silsesquioxane 4 within the polymerization initiation temperature range is dispersed in the thermosetting resin 5, it is flexible before the impregnation treatment, making it possible to wind it without gaps at the interface with the main insulating layer 9. Furthermore, since the polymerization of silsesquioxane 4 is completed at the curing temperature of the thermosetting resin 5 being impregnated, a cross-linked structure of silsesquioxane 4 with corona resistance is formed within the thermosetting resin, and a cross-linked structure can also be formed with silica particles. Due to this feature, when activated gases such as ozone (O3) and atomic oxygen (O) are generated due to partial discharge, the deterioration of the surrounding thermosetting resin 5 can be suppressed, and corona resistance can be exhibited.

[0053] <Thermosetting Resin> Any thermosetting resin 5 that retains flexibility after being applied to the fibrous insulating substrate 6 can be used as appropriate, and its type is not particularly limited. Examples of thermosetting resins 5 having such properties include polyimide resins, bismaleimide resins, unsaturated polyester resins, polyesterimide resins, epoxy resins, silicone resins, phenolic resins, and alkyd resins. Two or more of these resins may be used in combination depending on the application and the mechanical properties required of the resin composition.

[0054] <Fibrous insulating substrate> Any fibrous insulating substrate 6 that has insulating properties and can be coated with a thermosetting resin can be used as appropriate, and its type is not particularly limited. Examples of fibrous insulating substrates 6 having such properties include glass cloth, polyester cloth, Tetron cloth, and mica sheet. In any of the above fibrous insulating substrates, the substrate thickness is preferably in the range of 1 μm or more and 100 μm or less.

[0055] In addition to the components described above, additives may be added as necessary to the constituent materials of the semiconductive tape 1 according to the embodiment, as long as they do not hinder the effects of the present disclosure. Other additives that may be added as materials for the semiconductive tape 1 include reactive diluents, viscosity modifiers such as toluene and xylene, curing accelerators, anti-sagging agents, anti-settling agents, defoaming agents, leveling agents, slip agents, dispersants, and substrate wetting agents.

[0056] Next, the method for manufacturing the semiconducting tape 1 according to this embodiment 1 will be explained with reference to Figure 5. Figure 5 is a flowchart showing the manufacturing process in the method for manufacturing the semiconducting tape 1 according to this embodiment 1.

[0057] First, the thermosetting resin 5 and silsesquioxane 4 are kneaded together (step S501). It is preferable to apply shear mixing, which involves applying shear force, to the kneading process of silsesquioxane 4 into the thermosetting resin 5. Applying shear force makes it possible to uniformly disperse the silsesquioxane 4 within the thermosetting resin 5.

[0058] Any mixing device capable of mixing while applying shear force can be used for shear mixing, and the type is not particularly limited. Specific examples include bead mill mixers, three-roll mill mixers, homogenizer mixers, and laboplast mill mixers.

[0059] Next, silica particles 2 and conductive particles 3 are kneaded into a mixture of thermosetting resin 5 and silsesquioxane 4 (step S502). It is preferable to apply shear mixing, which involves applying shear force, to the kneading process of silica particles 2 and conductive particles 3 into the thermosetting resin 5. By applying shear force, it is possible to uniformly disperse the silica particles 2 and conductive particles 3 in the thermosetting resin 5.

[0060] Furthermore, a curing agent is added to the mixture of thermosetting resin 5, silica particles 2, and conductive particles 3 and mixed (step S503). After mixing, the mixture is applied to a fibrous insulating substrate 6 (step S504) and heated and cured (step S505) to obtain the desired semiconducting tape 1. The heating process after application is carried out with the applied surface facing the direction of gravity, and since the silica particles have a higher density than the thermosetting resin, it is possible to segregate them on the surface layer of the thermosetting resin.

[0061] In the manufacturing process of the semiconductive tape 1 described above, the coupling agent or surface treatment agent described above is added and mixed as needed. By modifying the surfaces of the silica particles 2 and conductive particles 3 with the coupling agent or surface treatment agent, the interface between the thermosetting resin 5, the silica particles 2, and the conductive particles 3 can be firmly bonded.

[0062] As described above, according to the embodiment of the semiconductive tape 1, semiconductive resin layers 11a and 11b in which silica particles 2 are dispersed and mixed are arranged on the fibrous insulating substrate 6, and the silica particles 2 are unevenly distributed near at least one side surface of the semiconductive tape 1. As a result, the silica particles 2 near the surface of the semiconductive tape 1 form a crosslinked structure with silsesquioxane 4, thereby exhibiting the effect of stopping partial discharge that occurs inside the void, suppressing the deterioration of the thermosetting resin 5 over time, and enabling stable corona resistance over a long period of time.

[0063] According to the embodiment of the semiconductive tape 1, since silsesquioxane 4 has a polymerization reaction initiation temperature lower than the curing temperature of the thermosetting resin that is impregnated, the semiconductive layer 10 is not made brittle, allowing the semiconductive tape 1 to be used stably and exhibiting the desired corona resistance.

[0064] According to the stator coil 7 of the embodiment, the winding 20 is formed from a conductor portion 8 made of bundled strands of conductor, a main insulating layer 9 made by winding mica tape around the outer circumference of the conductor portion 8, and a semiconducting layer 10 made by winding the semiconducting tape 1 around the outer circumference of the main insulating layer 9, and a thermosetting resin 5 is impregnated into the winding 20. Therefore, if voids occur in the thermosetting resins 5a and 5b, the oxidative decomposition of the thermosetting resins 5a and 5b near the voids is suppressed, and the initial corona resistance can be maintained over a long period of time.

[0065] According to the embodiment of the rotating electric machine 30, since the stator coil 7 is provided, it is possible to suppress the consumption of the thermosetting resin 5 and the loss of semiconductivity due to the effects of heat generation and discharge during the operation of the rotating electric machine 30. In other words, the silica particles 2 near the surface of the semiconducting tape 1 form a cross-linked structure with the silsesquioxane 4, which has the effect of stopping partial discharge that occurs inside the void, thereby suppressing the deterioration of the thermosetting resin 5 over time, and thus providing stable corona resistance over a long period of time. As a result, corona discharge that occurs in the minute space between the iron core and the main insulating material can be effectively and over a long period of time, and a semiconducting tape 1, stator coil 7, and rotating electric machine 30 with high reliability over a long period of time can be provided.

[0066] Preferred embodiments of this disclosure have been described above with reference to the attached drawings, but it goes without saying that this disclosure is not limited to these examples. The shapes and combinations of the components shown in the above examples are just examples and can be modified in various ways based on design requirements, etc., without departing from the spirit of this disclosure.

[0067] Furthermore, while various exemplary embodiments and examples are described in the above embodiments, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the technology disclosed in the embodiments. For example, this includes modifying, adding, or omitting at least one component, or even extracting at least one component and combining it with other components.

[0068] 1. Semiconductive tape (semiconductive material), 2. Silica particles, 3. Conductive particles, 4. Silsesquioxane, 5, 5a, 5b. Thermosetting resin, 6. Fibrous insulating substrate, 7. Stator coil, 8. Conductor part, 9. Main insulating layer (insulating layer), 10. Semiconductive layer, 11, 11a, 11b. Semiconductive resin layer, 12b, 13b. Surface, 20. Winding, 30. Rotating electric machine

Claims

1. A semiconductive member comprising a semiconductive resin layer disposed on a fibrous insulating substrate, the semiconductive resin layer containing silica particles, conductive particles, and silsesquioxane within a thermosetting resin, wherein the silica particles are unevenly distributed on the surface of the semiconductive resin layer.

2. The semiconducting member according to claim 1, wherein the polymerization initiation temperature of the silsesquioxane is higher than 100°C and lower than the curing temperature of the thermosetting resin subjected to impregnation treatment.

3. The semiconducting member according to claim 1 or 2, wherein the thermosetting resin is at least one of polyimide resin, bismaleimide resin, unsaturated polyester resin, polyesterimide resin, epoxy resin, and silicone resin.

4. The semiconductive member according to any one of claims 1 to 3, wherein the particle size of the silica particles is 1 nm or more and 20 μm or less.

5. The amount of silica particles blended into the thermosetting resin of the semiconducting resin layer is in the range of 1 vol% or more and 50 vol% or less, according to any one of claims 1 to 4.

6. The semiconductive member according to any one of claims 1 to 5, wherein the conductive particles are a conductive carbon material, and the conductive carbon material is at least one of carbon black, graphite, conductive diamond, carbon fiber, carbon nanotubes, and expanded graphite.

7. The semiconductive member according to any one of claims 1 to 6, wherein the semiconductive resin layer is filled with inorganic particles consisting of at least one selected from layered clay mineral particles, oxide particles, and nitride particles.

8. The semiconductive resin layer has a first region located on the surface side of the center in the thickness direction and a second region located on the opposite side of the surface side of the center, and if V1 is the volume fraction of the silica particles in the first region and V2 is the volume fraction of the silica particles in the second region, then the relationship V1 / V2 ≥ 2 is satisfied, the semiconductive member according to any one of claims 1 to 7.

9. The semiconducting member according to any one of claims 1 to 8, wherein the average interparticle distance of the silica particles unevenly distributed on the surface is less than 1 μm.

10. A stator coil having a winding comprising: a conductor portion formed by bundling strands of conductors; an insulating layer wound around the outer circumference of the conductor portion; and a semiconducting layer in which a semiconducting member according to any one of claims 1 to 9 is wound around the outer circumference of the insulating layer.

11. A rotating electric machine comprising a stator coil as described in claim 10.

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