WO2024154213A1 - Thermosetting resin composition, stator coil, and rotary electric machinery - Google Patents

Abstract

A thermosetting resin composition (3) according to the present application comprises a thermosetting resin (1), a curing agent that cures the thermosetting resin (1), and an organic insulating-gas-generating agent (2) that generates an insulating gas by pyrolysis. Insulating gas other than oxygen gas is generated by the organic insulating-gas-generating agent (2) at a temperature higher than the curing temperature of the thermosetting resin (1) but 300°C or lower. Long-term suppression of partial discharge in the insulating layer is realized and electric insulation of the iron core and coil conductor is guaranteed.

Description

Thermosetting resin composition, stator coil and rotating electric machine

This application relates to a thermosetting resin composition, a stator coil, and a rotating electric machine.

In order to miniaturize and increase the power output of high-voltage rotating electrical machines such as industrial induction motors, water turbine generators, and turbine generators, efforts are being made to increase the voltage and power density of rotating electrical machines. As a result, the structure of coils for high-voltage equipment is becoming more dense, and the main insulating layer, which is made up of insulating tape and insulating varnish, is required to have the properties to withstand high voltages for long periods of time.

　The stator coil of a conventional high-voltage rotating electric machine consists of a coil conductor and a main insulating layer made of mica tape, corona prevention tape (corona prevention layer), and insulating varnish. The coil conductor is wrapped with mica tape and corona prevention tape in that order, and the stator coil is assembled into the stator core. The insulating varnish is then vacuum-pressurized and impregnated with a thermosetting resin composition, and then heat-cured to form the main insulating layer.

However, if air bubbles, peeling, or other voids form in the main insulation layer during the manufacturing process, these voids will be exposed to a high electric field due to the increased voltage and power density, and will become the starting point for partial discharges. Partial discharges generated in these voids will cause electrical trees, an electrical breakdown phenomenon, to branch and progress in the main insulation layer between the coil conductors, and between the coil conductors and the iron core. Ultimately, they will penetrate the main insulation layer, causing insulation breakdown.

As a method for suppressing partial discharge in the gap, a main insulating layer made of an insulating varnish and mica tape containing an inorganic insulating gas generating agent and a resin composition, a stator coil made of the main insulating layer, and a rotating electric machine equipped with the stator coil have been disclosed (see, for example, Patent Document 1).

When a partial discharge occurs in the gaps of the insulation system material, the inorganic insulating gas generating agent is decomposed by the partial discharge energy, generating an insulating gas containing carbon dioxide, oxygen, and nitrogen. The insulating gas has the function of capturing negative ions generated by partial discharge, and carbon dioxide also generates oxygen molecules with higher electron attachment properties through secondary decomposition, which promotes the capture of the negative ions and suppresses partial discharge. Furthermore, the insulating gas generated by the insulating gas generating agent has the function of increasing the pressure in and near the gaps in the main insulation layer, which also has the effect of improving the partial discharge inception voltage.

JP 2016-201930 A (paragraph 0031, FIG. 3)

However, in the resin compositions used in the conventional high-voltage equipment described above, oxygen is generated from the inorganic insulating gas generating agent. When partial discharge occurs in the gap, this oxygen is used as a raw material to generate ozone and atomic oxygen, accelerating the oxidative deterioration of the insulating layer. In addition, the foaming start temperature of inorganic insulating gas generating agents is high, at around 300°C to 1000°C, so there is a problem that the main insulating layer is thermally deteriorated before the foaming start temperature is reached.

This application discloses technology to solve the problems described above, and aims to provide a thermosetting resin composition, a stator coil, and a rotating electric machine that can suppress partial discharge in the main insulation layer over a long period of time and ensure electrical insulation between the iron core and the coil conductor.

The thermosetting resin composition disclosed in this application is a thermosetting resin composition containing a thermosetting resin, a curing agent that cures the thermosetting resin, and an organic insulating gas generating agent that generates an insulating gas by thermal decomposition, and is characterized in that the organic insulating gas generating agent generates the insulating gas other than oxygen gas at a temperature higher than the curing temperature of the thermosetting resin and not higher than 300°C.

The stator coil disclosed in this application is characterized in that the outer layer of the coil conductor is composed of a main insulating layer using the above-mentioned thermosetting resin composition.

The rotating electric machine disclosed in this application is characterized by having the above-mentioned stator coil.

This application makes it possible to suppress partial discharges in the insulation layer over the long term and ensure electrical insulation between the iron core and the coil conductor.

2 is a schematic cross-sectional view showing the structure of a main insulating layer using a thermosetting resin composition according to the first embodiment. FIG. 11 is a schematic cross-sectional view showing the structure of a main insulating layer using a thermosetting resin composition according to embodiment 2. FIG. 11 is a schematic cross-sectional view showing the structure of a stator coil having a main insulating layer using a thermosetting resin composition according to embodiment 3. FIG. 13 is a schematic cross-sectional view showing the structure of a rotating electric machine including a stator coil having a main insulating layer using a thermosetting resin composition according to embodiment 4. FIG.

Embodiment 1.
FIG. 1 is a schematic cross-sectional view showing the structure of a main insulating layer using a thermosetting resin composition according to the first embodiment of the present invention. As shown in FIG. 1, the main insulating layer 7 of the first embodiment is composed of a mica tape 6 and a thermosetting resin composition 3 as an insulating varnish. The thermosetting resin composition 3 contains a thermosetting resin 1 and an organic insulating gas generating agent 2, and the organic insulating gas generating agent 2 is dispersed in the matrix of the thermosetting resin 1. The thermosetting resin composition 3 may be mixed as necessary as a constituent material of the mica tape 6. The thermosetting resin composition 3 used in the main insulating layer 7 will be described below.

<Thermosetting resin>
As the thermosetting resin 1, from the viewpoint of improving heat resistance, adhesiveness, electrical insulation, and mechanical strength, epoxy resin, phenol resin, unsaturated polyester resin, imide resin, silicone resin, etc. are preferable, and among them, epoxy resin is more preferable. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A type novolac type epoxy resin, bisphenol F type novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, salicylaldehyde novolac type epoxy resin, diglycidyl ether of bifunctional phenols, halogenated bifunctional phenols, hydrogenated bifunctional phenols, diglycidyl ether of bifunctional alcohols, halogenated bifunctional alcohols, and hydrogenated bifunctional alcohols. These epoxy resins may be used alone or in combination of two or more kinds. On the other hand, from the viewpoint of improving the balance of material cost, viscosity, and heat resistance, it is preferable to use a reaction product of epichlorohydrin and a bisphenol A compound as the thermosetting resin 1.

<Curing Agent>
A curing agent is added to the thermosetting resin composition 3 in order to cure the thermosetting resin 1. Any curing agent that can cure by chemically reacting with the thermosetting resin 1 can be used as appropriate, and the type is not limited. Examples of such curing agents include amine-based curing agents, acid anhydride-based curing agents, imidazole-based curing agents, polymercaptan-based curing agents, phenol-based curing agents, Lewis acid-based curing agents, and isocyanate-based curing agents. In addition, a catalyst that cures the thermosetting resin 1 may be added as an alternative to the curing agent.

Specific examples of the amine-based curing agent include, for example, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, dipropylenediamine, polyetherdiamine, 2,5-dimethylhexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis(hexamethyl)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylethanolamine, tri(methylamino)hexane, dimethylaminopropylamine, diethylamine, These include nopropylamine, methyliminobispropylamine, menthene diamine, isophorone diamine, bis(4-amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, 3,9-bis(3-aminopropyl)2,4,8,10-tetraoxaspiro(5,5)undecane, m-xylylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, dicyandiamide, and organic acid dihydrazides.

Specific examples of acid anhydride-based hardeners include dodecenyl succinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanedioic) anhydride, poly(phenylhexadecanedioic) anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene dicarboxylic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid, ethylene glycol bistrimellitate, glycerol tristrimellitate, HET anhydride, tetrabromophthalic anhydride, nadic anhydride, methylnadic anhydride, and polyazelaic anhydride. These acid anhydrides may be used alone or in combination of two or more. The amount of the acid anhydride is not particularly limited, and may be appropriately adjusted depending on the type of acid anhydride used, the type of thermosetting resin 1, and the like. For example, when a bisphenol-type epoxy resin is used as the thermosetting resin 1, the amount of the acid anhydride is preferably 10 to 150 parts by mass, more preferably 30 to 120 parts by mass, and even more preferably 50 to 100 parts by mass, relative to 100 parts by mass of the bisphenol-type epoxy resin. Such an amount of the acid anhydride allows the thermosetting resin composition 3 to be appropriately cured. When a bisphenol-type epoxy resin and a bisphenol-type curing agent are used, the equivalent ratio of the acid anhydride group of the acid anhydride to the epoxy group of the epoxy resin is not particularly limited, but is preferably 0.7 to 1.3, more preferably 0.8 to 1.2, and even more preferably 0.9 to 1.1. If the equivalent ratio is less than 0.7, the workability when forming the main insulating layer 7 tends to decrease. On the other hand, if the equivalent ratio exceeds 1.3, the heat resistance of the main insulating layer 7 tends to decrease.

Specific examples of imidazole-based hardeners include imidazole-based compounds such as 2-methylimidazole, 2-undecylimidazole, 1,2-dimethylimidazole, 2-A-methylimidazole, 2-butadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Specific examples of polymercaptan-based hardeners include polysulfides and thioesters.

Furthermore, a curing accelerator may be added in combination with the curing agent to accelerate or control the curing reaction of the thermosetting resin 1. In particular, when an acid anhydride curing agent is added, the curing reaction is slower than with other curing agents such as amine curing agents, so a curing accelerator is often used. Preferable curing accelerators for acid anhydride curing agents include tertiary amines or their salts, quaternary ammonium compounds, imidazoles, and alkali metal alkoxides.

A reactive diluent may be added to the curing agent. The reactive diluent may be a styrene monomer, a monomer with a hydrocarbon functional group added to the phenyl group, a methacrylic monomer, or an acrylic monomer. The methacrylic monomer is not particularly limited as long as it does not impair the curing of the epoxy resin, and examples of the methacrylic monomer include linear methacrylate, branched methacrylate, and cyclic methacrylate. From the viewpoint of heat resistance, it is preferable to use linear methacrylate as the methacrylic monomer. Examples of linear methacrylate include lauryl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate. These linear methacrylates may be used alone or in combination of two or more. The acrylic monomer is not particularly limited as long as it does not impair the curing of the epoxy resin, and examples of the acrylic monomer include linear acrylate, branched acrylate, and cyclic acrylate. From the viewpoint of heat resistance, it is preferable to use a linear acrylate as the acrylic monomer. Examples of linear acrylates include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, isobornyl acrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, and 2-(2,4,6-tribromophenoxy)ethyl acrylate. These linear acrylates may be used alone or in combination of two or more. The amount of reactive diluent is not particularly limited and may be adjusted as appropriate.

<Organic insulating gas generating agent>
As the organic insulating gas generating agent 2, any organic insulating gas generating agent 2 that decomposes due to a temperature rise caused by discharge energy to generate an insulating gas such as nitrogen gas, carbon dioxide gas, carbon monoxide, or ammonia gas can be used appropriately, and the type is not particularly limited. Examples of the organic insulating gas generating agent 2 having such properties include azo-based blowing agents such as azodicarbonamide (ADCA) and azobisisobutyronitrile, and dinitrosopentamethylenetetramine (DPT) and N,N'-dinitroso Nitroso-based blowing agents such as N,N'-dimethylterephthalamide, hydrazide-based blowing agents such as p-toluenesulfonylhydrazide, p,p'-oxybisbenzenesulfonylhydrazide (OBSH), benzenesulfonylhydrazide, hydrazodicarbonamide (HDCA), trihydrazinotriazine, etc. can be used. The organic insulating gas generating agent 2 described above can be used alone or as a mixture of two or more kinds.

The lower limit of the decomposition temperature of the organic insulating gas generating agent 2 is preferably the curing temperature of the thermosetting resin 1. On the other hand, the upper limit of the decomposition temperature of the organic insulating gas generating agent 2 is preferably 300°C, more preferably 250°C. If the decomposition temperature of the organic insulating gas generating agent 2 does not reach the above lower limit, the organic insulating gas generating agent 2 foams when the thermosetting resin composition 3 is heated and cured, and air bubbles are mixed into the cured product of the thermosetting resin composition 3. On the other hand, the above-mentioned organic insulating gas generating agent 2 decomposes at a temperature range of 300°C or less, and there is no organic insulating gas generating agent 2 that decomposes above the upper limit of 300°C. Here, the decomposition temperature is expressed as a temperature that is 10 parts by mass less than 100 parts by mass at room temperature.

The lower limit of the content of the organic insulating gas generating agent 2 relative to 100 parts by mass of the thermosetting resin 1 is preferably 0.25 parts by mass, and more preferably 1 part by mass. If the content of the organic insulating gas generating agent 2 relative to 100 parts by mass of the thermosetting resin 1 is less than 0.25 parts by mass, the amount of insulating gas generated is small, and partial discharge resistance characteristics cannot be fully exhibited. On the other hand, the upper limit of the content of the organic insulating gas generating agent 2 relative to 100 parts by mass of the thermosetting resin 1 is preferably 50 parts by mass, and more preferably 40 parts by mass. If the content of the organic insulating gas generating agent 2 relative to 100 parts by mass of the thermosetting resin 1 exceeds 50 parts by mass, the strength and fusion properties of the thermosetting resin 1 become insufficient due to the relatively small amount of matrix. In addition, since the interparticle distance between the organic insulating gas generating agents 2 is small, when partial discharge begins, decomposition of the organic insulating gas generating agent 2 occurs continuously, and partial discharge resistance characteristics cannot be fully exhibited.

The lower limit of the average diameter of the organic insulating gas generating agent 2 is preferably 1 μm, and more preferably 5 μm. On the other hand, the upper limit of the average diameter of the organic insulating gas generating agent 2 is preferably 50 μm, and more preferably 40 μm. If the average diameter of the organic insulating gas generating agent 2 is less than 1 μm, the probability of contact between the electrical tree and the organic insulating gas generating agent 2 decreases, and the partial discharge suppression effect cannot be fully exerted. Conversely, if the average diameter of the organic insulating gas generating agent 2 exceeds 50 μm, the diameter of the bubbles formed by the decomposition of the organic insulating gas generating agent 2 becomes large, and the partial discharge resistance characteristics decrease. Here, the average particle diameter is represented by the median diameter D50 of the volumetric particle size distribution in the dispersion liquid.

Furthermore, according to the first embodiment of the present application, the thermal decomposition residue of the organic insulating gas generating agent 3 has low reactivity with water, and it is possible to suppress thermal deterioration of the main insulating layer due to heat generation accompanying the chemical reaction.

Thermosetting resin composition 3 may be blended with a foaming assistant together with the organic insulating gas generating agent 2. The foaming assistant is not particularly limited as long as it promotes the thermal decomposition of the organic insulating gas generating agent 2, and examples thereof include urea compounds.

The lower limit of the amount of foaming aid to be mixed with respect to 100 parts by mass of organic insulating gas generating agent 2 is preferably 5 parts by mass, and more preferably 50 parts by mass. On the other hand, the upper limit of the amount of foaming aid to be mixed with is preferably 200 parts by mass, and more preferably 150 parts by mass. If the amount of foaming aid mixed with is less than 5 parts by mass, the effect of decomposing the chemical foaming agent may be insufficient. Conversely, if the amount of foaming aid mixed with exceeds 200 parts by mass, there is a risk that the organic insulating gas generating agent 2 may unintentionally decompose during heating and curing of the thermosetting resin composition 3, during cured storage, etc.

In addition to the above-mentioned components, additives may be added as necessary to the constituent materials of the thermosetting resin composition 3 according to this embodiment, so long as they do not impair the effects of the present application. Other additives that may be added to the materials of the thermosetting resin composition 3 include reactive diluents, viscosity regulators such as toluene and xylene, curing accelerators, anti-sagging agents, anti-settling agents, defoamers, leveling agents, slip agents, dispersants, and substrate wetting agents.

In this way, in the first embodiment of the present application, the thermosetting resin composition 3 contains the thermosetting resin 1 and the organic insulating gas generating agent 2. By using the thermosetting resin composition 3 containing the organic insulating gas generating agent 2 for the main insulating layer 7, an insulating gas that does not contain oxygen gas, such as nitrogen and carbon dioxide, is generated by thermal decomposition, and the internal pressure in the gap and its vicinity is increased, thereby making it possible to suppress the occurrence of partial discharge. In addition, compared to the case where the thermosetting resin composition 3 containing an inorganic insulating gas generating agent is used for the main insulating layer 7, the partial discharge inception voltage of the main insulating layer 7 is improved, and the discharge suppression effect can be fully exerted even when the temperature rise due to the discharge energy is small. As a result, partial discharges occurring inside the bubbles during operation of the rotating electric machine can be suppressed, and the life of the main insulating layer can be extended.

As described above, the thermosetting resin composition 3 according to the first embodiment is a thermosetting resin composition 3 consisting of a thermosetting resin 1, a curing agent for curing the thermosetting resin 1, and an organic insulating gas generating agent 2 for generating an insulating gas by thermal decomposition. The organic insulating gas generating agent 2 generates an insulating gas other than oxygen gas at a temperature higher than the curing temperature of the thermosetting resin 1 and below 300°C. Since the insulating gas does not contain oxygen, not only can the oxidation deterioration of the main insulating layer caused by ozone and atomic oxygen be suppressed, but also, since the insulating gas is generated at a low temperature range higher than the curing temperature and below 300°C, the time exposed to partial discharge energy can be shortened and thermal deterioration of the main insulating layer can be suppressed. In addition, by generating insulating gases such as nitrogen and carbon dioxide that do not contain oxygen gas by thermal decomposition and increasing the internal pressure in the void and its vicinity, the occurrence of partial discharge can be suppressed. Furthermore, compared to when a thermosetting resin composition 3 containing an inorganic insulating gas generating agent is used for the main insulating layer 7, the partial discharge inception voltage of the main insulating layer 7 is improved, and the discharge suppression effect can be fully exerted even when the temperature rise due to the discharge energy is small.

Embodiment 2.
In the second embodiment, a case where a thermosetting resin composition further containing an inorganic nanofiller is used will be described.

FIG. 2 shows a schematic cross-sectional view showing the structure of a main insulating layer using a thermosetting resin composition according to embodiment 2 of the present application. As shown in FIG. 2, the main insulating layer 7 of embodiment 2 is composed of a mica tape 6 and a thermosetting resin composition 30 as an insulating varnish. The thermosetting resin composition 30 is the thermosetting resin composition 3 of embodiment 1, with inorganic nano-filler 8 further dispersed in the matrix of the thermosetting resin 1.

<Inorganic nanofiller>
The inorganic nano-filler 8 is not easily scraped off even if a partial discharge occurs in the main insulating layer 7, and therefore serves as a physical barrier to the electrical tree propagating in the main insulating layer 7, causing the electrical tree to branch out in a dendritic form. Therefore, the propagation speed of the electrical tree is slowed down, and the probability of contact with the organic insulating gas generating agent 2 is improved, thereby improving the partial discharge resistance characteristics.

As the inorganic nanofiller 8, metal oxides such as titanium oxide, silica, aluminum oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, potassium titanate, magnesium oxide, and calcium oxide are preferred, and among these, titanium oxide, silica, and magnesium hydroxide are more preferred. These inorganic nanofillers 8 may be used alone or in combination of two or more types.

The shape of the inorganic nanofiller 8 is not particularly limited, and is preferably granular, spherical, or scaly. Among these, a spherical shape is more preferable from the viewpoint of dielectric breakdown resistance and strength. Here, a spherical shape means a sphere in which the ratio of the minimum diameter to the maximum diameter in a cross section passing through the center of gravity is 90% or more.

The lower limit of the average particle diameter of the inorganic nanofiller 8 is preferably 0.5 nm, and more preferably 1 nm. The upper limit of the average particle diameter of the inorganic nanofiller 8 is preferably 1 μm, and more preferably 0.5 μm. If the average particle diameter of the inorganic nanofiller 8 is less than 0.5 nm, the particle diameter is smaller than the electrical tree diameter and does not act as a physical barrier, so the effect of inhibiting the progression of the electrical tree cannot be fully exerted. On the other hand, if the average particle diameter of the inorganic nanofiller 8 exceeds 1 μm, the probability of contact with the electrical tree is low and the effect of inhibiting the progression of the tree cannot be fully exerted. Here, the average particle diameter is represented by the median diameter D50 of the volumetric particle size distribution in the dispersion liquid.

The lower limit of the content of the inorganic nanofiller 8 is preferably 1 vol.%, more preferably 3 vol.%. The upper limit of the content of the inorganic nanofiller 8 is preferably 20 vol.%, more preferably 10 vol.%. Here, the volume content of the inorganic nanofiller 8 is a percentage value obtained by dividing the volume of the inorganic nanofiller 8 by the volume of the thermosetting resin composition 3. If the content of the inorganic nanofiller 8 is less than 1 vol.%, the probability of contact with the electrical tree is low, and the effect of suppressing the progression of the electrical tree cannot be fully exerted. On the other hand, if the content of the inorganic filler 8 exceeds 20 vol.%, the viscosity of the thermosetting resin composition 3 increases, and the workability when forming the main insulating layer 7 tends to decrease.

The inorganic nanofiller 8 may be used after its surface has been modified with a coupling agent or coated with a surface treatment agent for the purpose of improving adhesion to the thermosetting resin 1 or improving dispersibility in the thermosetting resin 1. Examples of such coupling agents include silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane, titanate-based coupling agents, and aluminum-based coupling agents. Examples of surface treatment agents include aluminum laurate, aluminum stearate, alumina iron stearate, silica, zirconia, and silicone. These coupling agents or surface treatment agents may be used alone or as a mixture of two or more types.

The rest of the configuration of the thermosetting resin composition 30 according to the second embodiment is the same as that of the thermosetting resin composition 3 according to the first embodiment, and the corresponding parts are given the same reference numerals and the description thereof is omitted.

In this way, in the second embodiment of the present application, the thermosetting resin composition 30 contains the thermosetting resin 1, the organic insulating gas generating agent 2, and the inorganic nano-filler 8. By using the thermosetting resin composition 30 containing the organic insulating gas generating agent 2 for the main insulating layer 7, the partial discharge inception voltage of the main insulating layer is improved and the discharge suppression effect can be fully exerted even when the temperature rise due to the discharge energy is small, compared to when the thermosetting resin composition containing the inorganic insulating gas generating agent is used for the main insulating layer. In addition, by containing the inorganic nano-filler in the thermosetting resin composition 3, the inorganic nano-filler becomes a physical barrier for the electrical tree and branches the electrical tree in a dendritic shape. Therefore, the propagation speed of the electrical tree is delayed, the probability of contact with the organic insulating gas generating agent is improved, and the partial discharge resistance characteristics can be improved. As a result, partial discharges occurring inside the bubbles during operation of the rotating electric machine can be suppressed, and the main insulating layer 7 can be made to have a long life.

As described above, the thermosetting resin composition 30 according to the second embodiment further contains inorganic nano-filler 8 made of metal oxide, which allows the electrical tree to branch into a dendritic shape, slowing down the rate of electrical tree growth and increasing the probability of contact with the organic insulating gas generating agent, thereby improving partial discharge resistance.

Embodiment 3.
In the third embodiment, a case will be described in which a stator coil is formed using a main insulating layer using the thermosetting resin composition according to the first and second embodiments of the present application.

Figure 3 shows a schematic cross-sectional view of a stator coil 23 according to embodiment 3. As shown in Figure 3, the stator coil 23 of embodiment 3 is composed of a coil conductor 9 formed by bundling strand conductors, a main insulating layer 7 formed by winding mica tape 6 around the outer layer of the coil conductor 9, and a corona prevention layer 11 formed by winding corona prevention tape around the outer layer of the main insulating layer 7. The thermosetting resin composition 3 of embodiment 1 or the thermosetting resin composition 30 of embodiment 2 is used for the main insulating layer 7. The thermosetting resin composition 3 and the thermosetting resin composition 30 contain an organic insulating gas generating agent 2.

Next, a method for manufacturing the stator coil 23 according to the third embodiment will be described. The method for manufacturing the stator coil 23 uses the coil fixing member 10 to apply a pressure impregnation process and a heat curing process to the core slots 17 using a thermosetting resin composition 3 as an insulating varnish, and includes a shear dispersion process, a mixing process, and a coating process.

The shear dispersion process is a process in which the organic insulating gas generating agent 2 is added to the thermosetting resin 1, sheared, and dispersed in the thermosetting resin 1. The organic insulating gas generating agent 2 is usually aggregated as secondary or tertiary particles before being added to the thermosetting resin 1, so the shear dispersion process must be performed to crush the secondary or tertiary particles of the organic insulating gas generating agent 2 and disperse them in the thermosetting resin 1. By appropriately setting the shear dispersion conditions, the aggregated and dispersed states of the organic insulating gas generating agent 2 can be adjusted. In the shear dispersion process, the thermosetting resin 1 and the organic insulating gas generating agent 2 are mixed by shear force. The device used in the shear dispersion process is not particularly limited as long as it is a mixing device that can apply a shear force to the organic insulating gas generating agent 2, and may be appropriately selected from known devices. An example of a device used in the shear dispersion process is a wet high-pressure shear dispersion device.

The mixing process is a process in which a curing agent is added to and mixed with the thermosetting resin 1 in which the organic insulating gas generating agent 2 is dispersed. The curing agent is dispersed in the thermosetting resin 1 by the mixing process. The method for mixing the curing agent with the thermosetting resin 1 is not particularly limited and may be appropriately selected from among known methods. For example, after the curing agent is added to the thermosetting resin 1, the curing agent and the thermosetting resin 1 may be mixed using a machine such as a stirrer. The above shear dispersion process and mixing process result in a thermosetting resin composition 3.

The coating process is a process of coating the thermosetting resin composition 3 on the stator coil 23. The method of coating the thermosetting resin composition 3 is not particularly limited and may be appropriately selected from among known methods. The method of coating the thermosetting resin composition 3 includes, for example, immersing the stator coil 23 in a container containing the thermosetting resin composition 3. The impregnation process includes, for example, vacuum impregnation, vacuum pressure impregnation, and normal pressure impregnation. The conditions of the impregnation process are not particularly limited and may be appropriately set depending on the types of the thermosetting resin composition 3 and the enameled wire that constitutes the coil conductor 9. In addition, the method of coating the thermosetting resin composition 3 includes a method of dripping the thermosetting resin composition 3 onto the stator coil 23. After the coating process, the thermosetting resin composition 3 is heated and cured to obtain the stator coil 23 with the main insulating layer 7. The thickness of the main insulating layer 7 is not particularly limited and may be appropriately set depending on the size of the stator coil 23 to be manufactured.

In this way, in the second embodiment of the present application, the stator coil 23 is provided with a thermosetting resin composition 3 containing an organic insulating gas generating agent 2, and a main insulating layer 7 using a thermosetting resin composition 30, which has the effect of improving the partial discharge inception voltage, suppressing partial discharges, and ensuring electrical insulation between the iron core and the coil conductor. It is thus possible to provide a stator coil that has excellent electrical insulation and reliability even after many years of use.

As described above, according to the stator coil 23 of the present embodiment 3, the outer layer of the coil conductor is made of the main insulating layer 7 using the thermosetting resin composition 3, 30 of the embodiment 1 or embodiment 2, which has the effect of improving the partial discharge inception voltage, suppressing partial discharges, and ensuring electrical insulation between the iron core and the coil conductor. It is thus possible to provide a stator coil that has excellent electrical insulation and reliability even after many years of use.

Embodiment 4.
In the fourth embodiment, a case will be described in which a rotating electric machine is configured using the stator coil according to the third embodiment of the present invention.

FIG. 4 shows a schematic cross-sectional view of a rotating electric machine 20 according to embodiment 4. As shown in FIG. 4, the rotating electric machine 20 according to embodiment 4 includes a gas cooler 22, a stator coil 23 as an armature, and a rotor 27 as a field magnet, within a frame 21.

A refrigerant for cooling the heat generated by power generation circulates within the frame 21, and the circulating refrigerant is cooled by a gas cooler 22. The stator coil 23 has a cylindrical stator core 24 and a stator winding 25. The stator core 24 is fixed within the frame 21, and the stator winding 25 is fixed to the inner circumference of the stator core 24. Both ends of the stator winding 25 in the axial direction of the stator core 24 protrude from the stator core 24 and form coil ends 26. A main lead is connected to one of the coil ends 26, and the power generated by the rotating electric machine 20 is taken out of the frame 21.

The rotor 27 has a rotating shaft 28, a rotor core 29, a first retaining ring 30, and a second retaining ring 31. The rotating shaft 28 protrudes axially outward from both axial ends of the rotor core 29, and the rotating shaft 28 and the rotor core 29 are arranged coaxially with the stator core 24. As the rotor 27 rotates, a magnetic field generated from the rotor core 29 crosses the stator winding 25, generating an electromotive force in the stator winding 25 and generating a current. The first retaining ring 30 and the second retaining ring 31 are attached to both axial ends of the rotor core 29 and fix the field winding wound around the rotor core 29.

In this way, in the fourth embodiment of the present application, the rotating electric machine 20 is configured with a stator coil having a main insulating layer 7 using a thermosetting resin composition 30 and a thermosetting resin composition 30, which contains an organic insulating gas generating agent 2, and this has the effect of improving the partial discharge inception voltage, suppressing partial discharges, and ensuring electrical insulation between the iron core and the coil conductor. As a result, it is possible to provide a rotating electric machine that has excellent electrical insulation and reliability even after many years of use.

As described above, the rotating electric machine 20 according to the fourth embodiment is provided with the stator coil 23 according to the third embodiment, which has the effect of improving the partial discharge inception voltage, suppressing partial discharges, and ensuring electrical insulation between the iron core and the coil conductor. As a result, it is possible to provide a rotating electric machine that has excellent electrical insulation and reliability even after many years of use.

In addition, in embodiment 4 of the present application, the thermosetting resin composition 3 of the present disclosure is used for the main insulating layer 7 of the stator coil 23 of the rotating electric machine 20, but the thermosetting resin composition of the present disclosure may also be used for the insulating layer of the stator coil of a rotating machine other than a rotating electric machine, such as an electric motor, a generator, a compressor, or a servo motor.

The present application will be described in detail below with reference to examples, but the present application should not be interpreted in a restrictive manner based on the description of these examples.

[Example 1]
100 parts by mass of epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation) was mixed with 5 parts by mass of an organic insulating gas generating agent (ADCA, manufactured by Sankyo Kasei Co., Ltd.) having a decomposition temperature of 160°C as an organic insulating gas generating agent while applying a shear force. A curing agent (an acid anhydride curing agent, manufactured by Showa Denko Materials Co., Ltd.) was added and mixed. The mixture was then heated and dried at 150°C to produce a sheet cured product.

[Example 2]
100 parts by mass of epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation) was mixed with 5 parts by mass of an organic insulating gas generating agent (ADCA, manufactured by Sankyo Kasei Co., Ltd.) having a decomposition temperature of 300°C while applying a shear force. A curing agent (an acid anhydride curing agent, manufactured by Showa Denko Materials Co., Ltd.) was added and mixed. The mixture was then dried by heating at 150°C to produce a sheet cured product.

[Comparative Example 1]
100 parts by mass of epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation) was mixed with 5 parts by mass of an organic insulating gas generating agent (ADCA, manufactured by Sankyo Kasei Co., Ltd.) having a decomposition temperature of 140°C while applying a shear force. A curing agent (acid anhydride curing agent, manufactured by Showa Denko Materials Co., Ltd.) was added and mixed. The mixture was then dried by heating at 150°C to produce a sheet cured product.

[Comparative Example 2]
100 parts by mass of epoxy resin (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation) was mixed with 5 parts by mass of an inorganic insulating gas generating agent (calcium carbonate, manufactured by Nitto Funka Kogyo Co., Ltd.) having a decomposition temperature of 600°C as an organic insulating gas generating agent while applying a shear force. A curing agent (an acid anhydride curing agent, manufactured by Showa Denko Materials Co., Ltd.) was added and mixed. The mixture was then heated and dried at 150°C to produce a sheet cured product.

Here, the compounds used in the thermosetting resin compositions of Examples 1-2 and Comparative Examples 1-2 are shown in Table 1.

A long-term voltage application test (V-t test) was conducted on the thermosetting resin compositions of Examples 1-2 and Comparative Examples 1-2 to evaluate their voltage resistance characteristics. An earth electrode of the evaluation device was placed on one side of the thermosetting resin composition, and a rod electrode was fixed to one side of the thermosetting resin composition with insulating resin. A voltage of 12.0 kV was applied to the rod electrode, and the insulation life until dielectric breakdown was measured. Using this procedure, a voltage application test was conducted on the thermosetting resin compositions of Examples 1-2 and Comparative Examples 1-2, and the insulation life until dielectric breakdown was measured.

The insulation life of the thermosetting resin compositions of Examples 1 and 2 and Comparative Examples 1 and 2 is shown in Table 2.

As shown by the insulation life in Table 2, the thermosetting resin compositions of Examples 1 and 2 have an improved insulation life until dielectric breakdown, compared to the thermosetting resin compositions of Comparative Examples 1 and 2. If the content of the organic insulating gas generating agent per 100 parts by mass of the thermosetting resin composition is less than 0.25 parts by mass or exceeds 50 parts by mass, the withstand voltage characteristics are reduced and the insulation life is shorter than that of Example 1.

Compare Example 1 and Comparative Example 1. In the thermosetting resin composition of Example 1, 5% by mass of ADCA, which has a melting point of 160°C, is filled in the epoxy resin as an organic insulating gas generating agent. On the other hand, in Comparative Example 1, 5% by mass of ADCA, which has a melting point of 140°C, is filled in the epoxy resin as an organic insulating gas generating agent. As shown by the insulation life in Table 2, in Example 1, the organic insulating gas generating agent dispersed in the epoxy resin decomposes due to a local temperature rise caused by partial discharge, improving the partial discharge inception voltage and suppressing partial discharge, so that the insulation life is extended. However, in Comparative Example 1, the decomposition temperature of the organic insulating gas generating agent is lower than the curing temperature of the thermosetting resin, and the organic insulating gas generating agent decomposes and forms bubbles during the heat curing process, so that partial discharge is likely to occur and the insulation life is shortened.

Compare Example 1 and Comparative Example 2. In the thermosetting resin composition of Example 1, 5% by mass of ADCA, which has a melting point of 210°C, is filled in the epoxy resin as an organic insulating gas generating agent. On the other hand, in Comparative Example 2, 5% by mass of calcium carbonate, which has a melting point of 600°C, is filled in the epoxy resin as an inorganic insulating gas generating agent. As shown by the insulation life in Table 2, in Example 1, the organic insulating gas generating agent dispersed in the epoxy resin decomposes due to a local temperature rise caused by partial discharge, improving the partial discharge inception voltage and suppressing partial discharge, resulting in a longer insulation life. However, in Comparative Example 2, the decomposition temperature of the organic insulating gas generating agent is high and the time of exposure to the temperature rise caused by the discharge energy is long, resulting in a shorter insulation life.

Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more of the embodiments are not limited to application in a particular embodiment, but may be applied to the embodiments alone or in various combinations. Thus, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases in which at least one component is modified, added, or omitted, and even cases in which at least one component is extracted and combined with components of another embodiment.

1. Thermosetting resin, 2. Organic insulating gas generating agent, 3. Thermosetting resin composition, 23. Stator coil, 20. Rotating electric machine.

Claims (10)

A thermosetting resin composition comprising a thermosetting resin, a curing agent for curing the thermosetting resin, and an organic insulating gas generating agent for generating an insulating gas by thermal decomposition,
A thermosetting resin composition, characterized in that the organic insulating gas generating agent generates the insulating gas other than oxygen gas at a temperature higher than the curing temperature of the thermosetting resin and not higher than 300°C. The thermosetting resin composition according to claim 1, characterized in that the organic insulating gas generating agent is at least one of azodicarbonamide, dinitrosopentamethylenetetramine, and oxybisbenzenesulfonylhydrazide. The thermosetting resin composition according to claim 1, characterized in that the average particle diameter of the organic insulating gas generating agent is 1 μm or more and 50 μm or less. The thermosetting resin composition according to claim 1, characterized in that the insulating gas generated from the organic insulating gas generating agent is at least one of nitrogen gas, carbon dioxide gas, carbon monoxide gas, and ammonia gas. The thermosetting resin composition according to claim 1, characterized in that the content of the organic insulating gas generating agent is 0.25 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the thermosetting resin. The thermosetting resin composition according to claim 1, characterized in that it contains an inorganic nanofiller made of a metal oxide. The thermosetting resin composition according to claim 6, characterized in that the average particle size of the inorganic nanofiller is 0.5 nm or more and 1 μm or less. The thermosetting resin composition according to claim 6, characterized in that the surface of the inorganic nanofiller is modified with a coupling agent or coated with a surface treatment agent. A stator coil in which the outer layer of the coil conductor is composed of a main insulating layer using the thermosetting resin composition according to any one of claims 1 to 8. A rotating electric machine comprising the stator coil according to claim 9.

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