JP7409980B2 - mold electrical equipment - Google Patents

Description

The present invention relates to molded electrical equipment.

Molded electrical equipment such as stationary devices, circuit breakers, and rotating machines are becoming smaller and lighter. Along with this, equipment wiring and components are becoming denser and insulation layers are becoming thinner. Therefore, mold varnishes are required to have lower viscosity in order to increase the ability to fill narrow spaces with insulating materials. Furthermore, cured mold varnishes used to coat metal and ceramic parts are required to have high toughness and low thermal expansion in order to suppress the occurrence of cracks. Furthermore, mold varnishes are required to have excellent storage stability for the purpose of reducing loss costs.

Cured epoxy resins have excellent heat resistance, adhesiveness, chemical resistance, mechanical strength, etc., and are preferably used as mold varnishes for electrical equipment such as stationary devices, circuit breakers, and rotating machines. However, the epoxy resin itself has a relatively high viscosity, and its cured product is hard and brittle. In order to improve this problem, mold varnishes containing various additives added to epoxy resins have been developed.

Patent Document 1 describes an epoxy resin and an acid anhydride as its curing agent, a vinyl monomer that contributes to low viscosity, crushed crystalline silica and fused silica that contribute to high thermal conductivity and low thermal expansion, and high toughness. A mold varnish containing composite core-shell rubber particles, which contributes to suppressing cracks caused by oxidation, has been disclosed.

JP 2017-110135 Publication

The mold varnish described in Patent Document 1 has excellent storage stability, low viscosity, and excellent castability, and the cured product has good fracture toughness, low thermal expansion, and heat resistance due to the synergistic effect of multiple organic and inorganic fillers. It had excellent properties and was suitable as an insulator for various molded electrical equipment. However, in order to make the insulating layer of molded electrical equipment thinner and to further reduce the size and weight of the equipment, it was necessary to further increase the dielectric breakdown voltage of the insulating layer.

An object of the present invention is to provide a molded electrical device in which the breakdown voltage of an insulating layer is improved without impairing the storage stability, low viscosity, fracture toughness, low thermal expansion, and heat resistance of the mold varnish.

A preferred example of the present invention includes a molded resin layer and an insulating layer,
The insulating layer has a phenoxy resin or an epoxy resin having a plurality of alcoholic hydroxyl groups in the side chain, at least one functional group selected from the group consisting of a vinyl group, an acrylate group, and a methacrylate group and one isocyanate group. Examples include molded electrical equipment which is a highly insulating resin having a mixture and/or reaction product of a polyfunctional monomer and a maleimide compound having a plurality of maleimide groups in its structure.

According to the present invention, a molded electrical device with improved breakdown voltage of an insulating layer can be realized without impairing the storage stability, low viscosity, fracture toughness, low thermal expansion, and heat resistance of the mold varnish.

FIG. 1 is a schematic cross-sectional view showing an example of a composite insulation structure of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of another composite insulation structure of the present invention. FIG. 2 is a schematic cross-sectional view showing an example in which the insulating layer of the present invention is installed on the surface of a molded resin layer. FIG. 3 is a diagram showing the relationship between the film thickness of a highly insulating resin layer and dielectric breakdown voltage. FIG. 3 is a diagram showing the relationship between the thickness of an insulating layer and dielectric breakdown voltage. FIG. 3 is a diagram showing the relationship between the film thickness and dielectric breakdown voltage of a polyimide film. FIG. 3 is a diagram showing the relationship between the thickness of an insulating layer and dielectric breakdown voltage. A diagram showing the relationship between the thickness and dielectric breakdown voltage of a molded single layer sample. FIG. 3 is a diagram showing a simulated molded transformer including an insulating layer. FIG. 3 is a diagram showing a simulated solid-state insulated switch including an insulating layer. FIG. 2 is a schematic cross-sectional diagram of a winding wire having a highly insulating resin layer. It is a figure which shows Table 1 which shows the component of the mold varnish used for an Example and a comparative example, and its viscosity.

In order to achieve the above-mentioned object of the present invention, the present inventor attempted to study how to increase the withstand voltage of a molded resin layer, mainly from the viewpoint of compositing an insulating layer. As a result, a long chain bifunctional epoxy resin or phenoxy resin having multiple hydroxyl groups in the side chain (hereinafter, both are abbreviated as phenoxy resin), a maleimide compound having multiple maleimide groups in the molecule, and the phenoxy resin A polyfunctional monomer having in its molecule one isocyanate group capable of chemically bonding with the hydroxyl group possessed by the compound, and at least one functional group selected from the group consisting of a vinyl group, an acrylate group, and a methacrylate group capable of chemically bonding with the maleimide compound. A cured film of a mixture of a certain polyfunctional isocyanate compound and/or a reaction product of the above-mentioned at least three components (hereinafter referred to as a highly insulating resin) has a dielectric breakdown voltage higher than that of a general mold resin or polyimide resin. I found out that it shows.

Furthermore, by coating or impregnating an insulating base material such as a polyimide film or aramid nonwoven fabric with a highly insulating resin, the dielectric breakdown voltage per unit thickness of the insulating layer 1 as a composite material having a multilayer structure or an impregnated structure can be increased. It was discovered that this material has a higher voltage resistance than polyimide film or aramid nonwoven fabric before composite formation. Furthermore, in a composite insulation structure in which the insulation layer 1 is provided inside and on the surface of the molded resin layer, it has been found that the dielectric breakdown voltage is dramatically increased compared to an insulation structure using only molded resin, leading to the present invention.

In the molded electrical device of the present invention, a single insulating layer is provided at at least one location selected from between the built-in component and the molded resin layer covering the component, inside the molded resin layer, or on the surface of the molded resin layer, or Provide multiple layers. That is, a molded resin layer having functions as an insulator and a structure, and an insulating layer 1 having a function of increasing the dielectric breakdown voltage of the molded resin layer are provided as independent layers in an insulating structure. By doing so, the insulating layer 1 can be coated without impairing the storage stability, low viscosity, and curability of the mold varnish, as well as the fracture toughness, low thermal expansion, and heat resistance of the mold resin layer that is the cured product. The overall dielectric breakdown voltage can be improved. Molded electrical equipment refers to electrical equipment whose electrical components are molded with an insulating resin such as epoxy resin or polyester resin. Electrical components include molded transformers, molded circuit breakers, insulated switches, electric motors, and insulated busbars.

Hereinafter, the composite insulation structure of the present invention will be explained in more detail based on the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the composite insulation structure of the present invention. This is an example of a composite insulation structure having an insulating layer 1 made of an insulating base material 3 and a highly insulating resin layer 4 on a built-in component 2, and a molded resin layer 5 on the insulating layer 1. Although there are no particular limitations on the method of forming the insulating layer 1, for example, the insulating layer 1 is formed by wrapping an insulating base material over the built-in component. Alternatively, the insulating layer 1 is formed by painting. Next, there is a method in which a paint that becomes a highly insulating resin layer is formed by painting or the like, and then dried and cured. Alternatively, a method may be used in which a film-like insulating layer 1 made of a composite of an insulating base material 3 and a highly insulating resin layer 4 is wound around a built-in component. The forming method can be arbitrarily selected depending on the shape of the built-in component.

As shown in FIG. 1, the thickness of the insulating layer 1 is thinner than the mold resin layer 5. As will be described later, the insulation layer 1 having the same thickness as the mold resin layer 5 has a higher dielectric breakdown voltage than the mold resin layer 5. Even if the insulating layer 1 is formed thinner than the molded resin layer 5, the insulation will be better than if only the molded resin layer 5, which has the same thickness as the insulating layer 1 and the molded resin layer 5, is formed on the surface of the built-in component. Molded electrical equipment with high breakdown voltage can be obtained.

FIG. 2 is a schematic cross-sectional view showing another example of the composite insulation structure of the present invention. The insulating layer 1 of this example has a highly insulating resin layer 4 on both sides of an insulating base material 3, and has a structure in which the insulating layer 1 is embedded in a molded resin layer. An example of a manufacturing method thereof is a method in which an insulating tube that covers the built-in component 2 is formed using an insulating layer 1, and then the built-in component 2 and the insulating layer 1 are integrally molded with a mold resin layer 5.

FIG. 3 is a schematic cross-sectional view showing an example in which an insulating layer 1 made by impregnating an insulating woven or non-woven fabric with a highly insulating resin is installed on the surface of a molded resin layer 5. An example of a manufacturing method thereof is a method in which an insulating layer 1 that has been previously molded and hardened by hot pressing is placed around the outer periphery of a built-in component, and a molded resin layer is formed within the insulating layer 1. The installation location of the insulating layer 1, the thickness of the insulating layer 1, single layer or multilayer structure, installation of a plurality of insulating layers 1, and other insulating configurations explained in each figure can be arbitrarily selected. Generally, as the total thickness of the insulating layer 1 increases, the dielectric breakdown voltage of the composite insulating structure increases.

Next, the insulating material used in the present invention will be explained.
The highly insulating resin is preferably used to have a material composition that can chemically bond with the epoxy resin and acid anhydride that are the binders of the mold resin layer 5, as well as with the radically polymerizable resin component. Among the materials, it is particularly preferable to use a material having a higher dielectric breakdown voltage per unit thickness than that of the molded resin layer. Such examples include (A) 100 parts by weight of a phenoxy resin having multiple alcoholic hydroxyl groups in the side chain, and (B) 5 parts by weight or more and 30 parts by weight or less of a maleimide compound having multiple maleimide groups in the molecule. , (C) has one isocyanate group capable of chemical bonding with the alcoholic hydroxyl group in the molecule, and a vinyl group, acrylate group, or methacrylate group capable of chemical bonding with a maleimide compound having a plurality of maleimide groups in the molecule. Examples include mixtures containing polyfunctional isocyanate compounds in a range of 2 parts by weight or more and 60 parts by weight or less, and reaction products thereof.

Phenoxy resin has a relatively high molecular weight and provides film-forming properties to highly insulating resins, improves adhesion to ceramics and various metals, and improves chemical bonding with epoxy resins and acid anhydrides contained in mold resins. It contributes to the formation of a bond, that is, to high adhesion with the mold resin layer.

The polyfunctional maleimide compound contributes to improving adhesion with polyimide resins, polyamideimide resins, and aramid resins, and also has the function of imparting curability to highly insulating resins. Since the polyfunctional isocyanate compound can chemically bond to both the phenoxy resin and the polyfunctional maleimide compound, it is a component that promotes curing of the highly insulating resin and contributes to improving heat resistance.

Highly insulating resins with such a structure can be dissolved in solvents such as methyl ethyl ketone, cyclohexanone, and tetrahydrofuran to form varnishes, so they have the advantage of being easy to apply and impregnate internal parts and film-like insulating substrates. .

The highly insulating resin varnish dissolved in an organic solvent as described above can be formed into a film on built-in components or an insulating base material by existing coating methods such as dipping, spraying, bar coater, curtain coater, etc. The drying conditions after application must be selected taking into account the boiling point of the varnishing solvent, but in the case of using tetrahydrofuran, it was at 50°C for about 30 minutes, and in the case of using methyl ethyl ketone, it was at 80°C for about 30 minutes. In the example using cyclohexanone, it is preferable to perform drying at 160° C. for about 30 minutes.

The curing conditions for the highly insulating resin are preferably 180° C. for about 1 hour, and the fully cured highly insulating resin exhibits high adhesiveness to polyimide resin, polyamide-imide resin, aramid resin, and various metals. In addition, when a polymerization catalyst such as a radical polymerization initiator is blended with the highly insulating resin, the curing temperature and curing time can be arbitrarily adjusted according to the polymerization initiation temperature of the catalyst.

Furthermore, the materials used in the present invention will be described in detail. As the phenoxy resin, a high molecular weight type resin that is solid at room temperature and has film-forming properties is preferably used. Its basic structure can be exemplified by bisphenol A type, bisphenol F type, bisphenol S type, or a copolymer type of the above basic structure.

More specifically, YP-50 (bisphenol A type phenoxy resin, styrene equivalent weight average molecular weight 73,000), YP-70 (bisphenol A type/bisphenol F type copolymerized phenoxy resin, styrene) manufactured by Nippon Steel Chemical & Materials Co., Ltd. YPS-007A30 (bisphenol A type/bisphenol S type copolymerized phenoxy resin, average molecular weight in terms of styrene 49,000), and the like. A liquid epoxy resin may be blended with these phenoxy resins to impart tackiness to the uncured highly insulating resin. The insulating layer 1 made of a highly insulating resin with adhesive properties can be installed on built-in components, etc. at a relatively low temperature, so that it is possible to increase the productivity of a molded electrical device containing the insulating layer 1.

Examples of maleimide compounds include 4,4'-diphenylmethane bismaleimide (Cas. No. 13676-54-5), phenylmethane maleimide (Cas. No. 67784-74-1), and bisphenol A diphenyl ether bismaleimide (Cas. No. 67784-74-1). 9922-55-7), 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide (Cas.No.105391-33-1), 1,6'-bismaleimide (2, Examples include 2,4-trimethyl)hexane (Cas. No. 39979-46-9). The aforementioned maleimide compound has excellent solubility and is suitable for making a highly insulating resin into a varnish.

Examples of polyfunctional isocyanate compounds include 2-isocyanatoethyl methacrylate (Cas. No. 30674-80-7) and 2-isocyanatoethyl acrylate (Cas. No. 13641-), which have a highly reactive vinyl group among vinyl isocyanates. 96-8), 1,1-(bisacryloyloxymethyl)ethyl isocyanate (Cas. No. 886577-76-0), 2-(2-methacrylooxyethyloxy)ethyl isocyanate (Cas. No. 107023-60) -9) etc. By selecting a compound having one isocyanate group in the molecule among the polyfunctional isocyanate compounds, gelation of the highly insulating resin varnish can be prevented.

It is preferable to further add to the highly insulating resin a urethanization catalyst that promotes the reaction between isocyanate groups and alcoholic hydroxyl groups. The urethanization catalyst is used in a range of 0.0002 or more and 0.1 parts by weight or less based on 100 parts by weight of the phenoxy resin, and is used in the reaction between the phenoxy resin and the polyfunctional isocyanate compound when forming a highly insulating resin into a varnish. It has the function of promoting the solubility of phenoxy resin. This contributes to increasing the concentration of the highly insulating resin varnish, improving the dissolution rate, and lowering the melting temperature, thereby improving the efficiency of manufacturing the highly insulating resin layer 4.

Specific examples of the urethanization catalyst include metal salts such as dibutyltin dilaurate, and tertiary amines such as triethylamine and N,N-dimethylcyclohexylamine.

Next, the insulating base material will be explained. As described above, the highly insulating resin layer 4 has the effect of increasing the insulation voltage of the insulating base material itself by being composited with the insulating base material. Furthermore, rather than using the highly insulating resin layer 4 alone, using it by impregnating and coating it on an insulating base material has the advantage of improving handling properties in the manufacturing process of molded electrical equipment.

Typical examples of insulating substrates include various films, porous materials, woven fabrics, and non-woven fabrics, but modified examples include enamel coatings on winding wires, specifically polyimide coatings, polyamide-imide coatings, polyester Also included are imide coatings and the like. There are no particular limitations on the material of these insulating base materials, provided that the wettability adjustment by surface treatment of the base material is taken into consideration. From the viewpoint of heat resistance, materials such as polyimide resins, polyamideimide resins, polyesterimide resins, aramid resins, liquid crystal polymers, cellulose, and glass that have a high melting temperature or do not have meltability are preferably used.

There are no particular restrictions on the molding resin material that can be applied to the molded electrical equipment having the composite insulation structure of the present invention, but it is important that the insulating material has reliability such as fracture toughness, low thermal expansion, and heat resistance, as well as dielectric breakdown voltage. For this purpose, it is preferable to apply a cured product of a low-viscosity mold varnish containing an organic/inorganic filler to the mold resin layer.

Particularly preferred examples include the following mold varnishes and cured products thereof.
In the present invention, the base material A contains an epoxy resin whose equivalent weight is 200 g/eq or less and a radical polymerization initiator, an acid anhydride that is liquid at room temperature, and an epoxy resin and an acid anhydride. curing agent B containing an epoxy resin curing catalyst that promotes the curing reaction of , styrene containing a radical polymerization inhibitor, an acid anhydride that is liquid at room temperature, and a reaction inducer C containing N-phenylmaleimide. A mold varnish consisting of a liquid can be preferably used. Furthermore, the mold varnish may contain core-shell rubber particles, crushed crystalline silica, fused silica, a dispersant, a coupling agent, and the like. The constituent materials of the mold varnish will be explained below.

(1) Epoxy resin The epoxy resin used in the present invention is preferably a bisphenol A type or bisphenol F type epoxy resin. As a more preferable epoxy resin, one having an epoxy equivalent of 200 g/eq or less is preferable from the viewpoint of reducing varnish viscosity.

Specifically, EPICLON840 manufactured by DIC Corporation (epoxy equivalent 180 to 190 g/eq, viscosity 9000 to 11000 mP·s/25°C), EPICLON850 (epoxy equivalent 183 to 193 g/eq, viscosity 11000 to 15000 mP·s/25°C) ), EPICLON830 (epoxy equivalent 165-177g/eq, viscosity 3000-4000mP・s/25℃), jER827 manufactured by Mitsubishi Chemical Corporation (epoxy equivalent 180-190g/eq, viscosity 9000-11000mP・s/25℃), jER828 (epoxy equivalent 184-194g/eq, viscosity 12000-15000mP・s/25℃), jER806 (epoxy equivalent 160-170g/eq, viscosity 1500-2500mP・s/25℃), jER807 (epoxy equivalent 160-175g/eq , viscosity 3,000 to 4,500 mP·s/25°C), etc.

From the viewpoint of heat resistance, it is preferable to use a bisphenol A type epoxy resin, and from the viewpoint of lowering the viscosity, it is preferable to use a bisphenol F type epoxy resin. Furthermore, in order to balance both properties, these epoxy resins can be used in a blend.

(2) Acid anhydride As the acid anhydride, it is preferable to use an acid anhydride that is liquid at room temperature. Examples include HN-2000 (acid anhydride equivalent: 166 g/eq, viscosity: 30-50 mPa・s/25°C), HN-5500 (acid anhydride equivalent: 168 g/eq, viscosity: 50-50 mPa・s/25°C), manufactured by Hitachi Chemical Co., Ltd. 80 mPa・s/25℃), MHAC-P (acid anhydride equivalent 178 g/eq, viscosity 150-300 mPa・s/25℃), EPICLON B-570H manufactured by DIC Corporation (acid anhydride equivalent 166 g/eq, viscosity 40 mPa·s/25°C).

(3) Reaction inducer C
As the reaction inducer C, a mixture of styrene containing 10 to 100 ppm of a polymerization inhibitor, N-phenylmaleimide, and the acid anhydride described in (2) is preferable. In particular, the styrene is 14 to 18 wt%, the N-phenylmaleimide is 24 to 30 wt%, and the acid anhydride is 53 to 61 wt%, and the molar ratio of the styrene and N-phenylmaleimide is equimolar or has an error of 5 moles. It is preferable to mix within the range of %. By mixing within this range, N-phenylmaleimide is dissolved in the mixed solution of the styrene and the acid anhydride, and precipitation of N-phenylmaleimide can be prevented even during storage in the winter when the room temperature is low, as well as during storage in the summer when the room temperature is high. Since self-polymerization during storage can also be suppressed, reaction inducer C with excellent storage stability can be produced.

The blending ratio of main agent A, curing agent B, and reaction inducing agent C will be explained. When the number of equivalents of the epoxy resin contained in the collected base material A is set to 1, the curing agent B and the reaction inducer C are collected so that the number of equivalents of the acid anhydride is in the range of 0.95 to 1, Blend. This can prevent insufficient curing reaction between the epoxy resin and the acid anhydride. In addition, the amount of the reaction inducer C is determined by combining the epoxy resin contained in the base agent A, the acid anhydride contained in the curing agent B, the styrene contained in the reaction inducer C, the acid anhydride, and the N- From the viewpoint of increasing toughness, it is preferable that the amount is in the range of 5 to 15% by mass based on the total amount of phenylmaleimide.

(4) Epoxy resin curing catalyst Examples of epoxy resin curing catalysts that promote the curing reaction between the epoxy resin of the present invention and acid anhydride include tertiary amines such as trimethylamine, triethylamine, tetramethylbutanediamine, and triethylenediamine; Amines such as dimethylaminoethanol, dimethylaminopentanol, tris(dimethylaminomethyl)phenol, N-methylmorpholine, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltrimethylammonium iodide, dodecyltrimethylammonium bromide, Dodecyltrimethylammonium chloride, dodecyltrimethylammonium iodide, benzyldimethyltetradecylammonium chloride, benzyldimethyltetradecylammonium bromide, allyldodecyltrimethylammonium bromide, benzyldimethylstearylammonium bromide, stearyltrimethylammonium chloride, benzyldimethyltetradecylammonium acetylate, etc. Quaternary ammonium salt of Imidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-azine-2-methylimidazole, 1- Imidazoles such as azine-2-undecyl, metal salts of amines and zinc octoate, cobalt, etc., 1,8-diaza-bicyclo(5,4,0)-undecene-7, N-methyl-piperazine, tetramethyl Amine tetraphenylborate such as butylguanidine, triethylammonium tetraphenylborate, 2-ethyl-4-methyltetraphenylborate, 1,8-diaza-bicyclo(5,4,0)-undecene-7-tetraphenylborate, Examples include phenylphosphine, triphenylphosphonium tetraphenylborate, aluminum trialkylacetoacetate, aluminum trisacetylacetoacetate, aluminum alcoholate, aluminum acylate, and sodium alcoholate.

The amount of the epoxy curing catalyst added is preferably in the range of 0.2 parts by mass or more and 2.0 parts by mass or less based on 100 parts by mass of the epoxy resin, which enables high-speed curing.

(5) Radical polymerization initiator Examples of radical polymerization catalysts include benzoin, benzoin compounds such as benzoinmethyl, acetophenone, acetophenone compounds such as 2,2-dimethoxy-2-phenylacetophenone, thioxanthone, 2,4 - Thioxanthone compounds such as diethylthioxanthone, bisazide compounds such as 4,4'-diazidochalcone, 2,6-bis(4'-azidobenzal)cyclohexanone, 4,4'-diazidobenzophenone, azobisisobutyl azo compounds such as lonitrile, 2,2-azobispropane, m,m'-azoxystyrene, hydrazone, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2, 5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, dicumyl peroxide, t-butylperoxymaleic acid, n-butyl-4,4-bis(t-butylperoxy)valerate , 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne, and organic peroxides such as dicumyl peroxide. Among them, from the viewpoint of storage stability, a radical polymerization initiator having a 10-hour half-life temperature of 100° C. or higher is preferably used.

The amount of the radical polymerization catalyst added should be in the range of 0.3 parts by mass or more and 1.0 parts by mass or less, based on the total amount of styrene and N-phenylmaleimide being 100 parts by mass, depending on the gelation time during the curing reaction. preferred from the viewpoint of adjustment.

(6) Silica It is preferable that the main ingredient A and curing agent B of the present invention contain crushed crystalline silica and fused silica from the viewpoint of crack resistance, high thermal conductivity, and low thermal expansion of the cured resin product.

Crushed crystalline silica is preferable as composite fine particles because it has low thermal expansion, high thermal conductivity, and is inexpensive. The preferred average particle size is 5 μm or more and 25 μm or less. Examples of such silica include SQ-H22 and SQ-H18 manufactured by Hayashi Kasei Co., Ltd., CRYSTALITE series manufactured by Ryumori Co., Ltd., and the like.

Fused silica has a lower thermal conductivity, a lower coefficient of thermal expansion, and a smaller thickening effect on mold varnish than crushed crystalline silica. Therefore, it is preferable to use it in combination with crushed crystalline silica, taking into account the properties required of the mold varnish. The preferred average particle size of fused silica is 5 μm or more and 25 μm or less. Examples of such silica include FD-5D, FB-12D, and FB-20D manufactured by Denki Kagaku Kogyo Co., Ltd.

(7) Core-shell rubber particles Core-shell rubber particles suppress the development of cracks to a minimum. Another criterion for selecting core-shell rubber particles is that they have excellent dispersibility in epoxy resins.

Examples of core-shell rubber particles include Paraloid EXL2655 (product name) manufactured by Rohm & Haas (average particle size 200 nm), Staphyloid AC3355 (product name) manufactured by Ganz Kasei Co., Ltd. (average particle size 0.1 to 0.5 μm), and Zefiac F351. (average particle size 0.3 μm), etc. As described above, it is preferable that the average particle size of the core-shell rubber particles is 0.1 μm or more and 1 μm or less.

The amount of the organic/inorganic filler composed of crushed crystalline silica, fused silica, and core-shell rubber particles is preferably in the range of 73 to 89% by mass based on the base material A and curing agent B, respectively. If the content is less than 73% by mass, the effects of organic/inorganic fillers such as thermal conductivity, toughness, thermal shock resistance, low thermal expansion, and heat resistance will deteriorate. On the other hand, if the blending amount exceeds 89% by mass, the viscosity of the varnish will significantly increase.

The preferred composition of the organic/inorganic filler is 33% to 97% by mass of crushed crystalline silica, 0 to 65% by mass of fused silica, and 1 to 3% by mass of core shell rubber particles. The composition range of these fillers is preferably adjusted according to the desired physical properties. Furthermore, mica may be added as long as it is 5% by mass or less based on the total amount of the mold varnish. Within this range, the heat resistance of the mold layer can be improved while suppressing thickening of the varnish.

(8) Coupling agent Various silane-based and titanate-based coupling agents can be used as the coupling agent. Examples of such coupling agents include epoxysilanes and vinylsilanes such as KBM-402, KBM-403, KBM-502, and KBM-504 manufactured by Shin-Etsu Chemical Co., Ltd., as silane-based coupling agents. It is mentioned as. Examples of the titanate coupling agent include S-151, S-152, and S-181 manufactured by Nippon Soda Co., Ltd.

(9) Dispersant As the dispersant, various nonionic surfactants are preferable, examples of which include BYK-W903, BYK-W980, BYK-W996, BYK-W9010 manufactured by BYK Chemie Japan Co., Ltd. I can do things.

These coupling agents and dispersants contribute to reducing the viscosity of the varnish by chemically bonding or adsorbing to the surface of the organic/inorganic filler and modifying the surface. Therefore, even if it is blended in excess, it cannot be chemically bonded or adsorbed to the surface of the organic/inorganic filler, and no further viscosity reduction effect can be expected. Moreover, excessive blending is not preferable because it lowers the glass transition temperature and thermal decomposition initiation temperature of the cured resin product. From the above, it is preferable that the amount of the coupling agent and dispersant used is in the range of 0.2 to 1 part by mass, based on 100 parts by mass of the total amount of organic/inorganic filler.

(Example)
The present invention will be specifically explained below by showing Examples and Comparative Examples. The following examples are for specific explanation of the present invention, and the scope of the present invention is not limited thereto, and may be freely modified within the scope of the inventive idea of the claims. It is possible. Note that the material composition ratios in Table 1 of FIG. 12 are weight ratios.

Reagents and evaluation methods are shown below.
(1) Test sample jER828: Bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent amount approximately 190 g/eq.

jER807: Bisphenol F type epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: approximately 170 g/eq.

HN-5500: 3- or 4-methyl-hexahydrophthalic anhydride manufactured by Hitachi Chemical Co., Ltd., acid anhydride equivalent 168 g/eq.

2E4MZ-CN: 1-cyanoethyl-2-ethyl-4-methylimidazole manufactured by Shikoku Kasei Kogyo Co., Ltd., epoxy curing catalyst.

25B: 1,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3 manufactured by NOF Corporation, radical polymerization initiator, 10-hour half-life temperature 128.4°C.

XJ-7: Crystalline crushed silica manufactured by Ryumori Co., Ltd., particle size of approximately 6.3 μm, crushed crystalline silica.

FB-20D: Fused silica manufactured by Denki Kagaku Kogyo Co., Ltd., particle size of approximately 22 μm, fused silica.

KBM-503: 3-methacryloxypropyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd., coupling agent.

KBM-403: 3-glycidoxypropyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd., coupling agent.

KS603: Manufactured by Shin-Etsu Chemical Co., Ltd., silicone antifoaming agent.

BTA731: Core shell rubber particles manufactured by Dow Chemical Company: Average particle size 0.1 to 0.5 μm.

BYK-W-9010: Dispersant manufactured by BYK Chemie Japan Co., Ltd.

Styrene: Styrene manufactured by Tokyo Kasei Kogyo Co., Ltd. Contains 30 ppm of 4-tert-butylcatechol as a radical polymerization inhibitor.

N-phenylmaleimide: N-phenylmaleimide manufactured by Tokyo Chemical Industry Co., Ltd.

YP-50: Phenoxy resin manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. Used as a film forming component of highly insulating resin.

Methyl ethyl ketone: Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., used as a solvent for highly insulating resins.

2-Isocyanatoethyl methacrylate: Karenz (registered trademark) MOI manufactured by Showa Denko K.K. Used as a modifier to introduce a methacrylate group into the side chain of YP-50 in a highly insulating resin.

N,N-dimethylcyclohexylamine: Urethane catalyst (Polycat 8) manufactured by San-Apro Co., Ltd. Used as a modified catalyst for YP-50.

BMI-1000: 4,4'-diphenylmethane bismaleimide manufactured by Daiwa Kasei Kogyo Co., Ltd., used as a crosslinking component of highly insulating resin.

4-tert-butylpyrocatechol: Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., used as a radical polymerization inhibitor.

Polyimide film: Manufactured by DuPont-Toray Co., Ltd., Kapton (registered trademark),
Aramid nonwoven fabric: DuPont Teijin Advanced Paper Co., Ltd., Nomex (registered trademark) 410.

(2) Preparation of highly insulating resin varnish In a 500 mL plastic bottle, 50 g of YP-50 (phenoxy resin), 8.8 g of BMI-1000 (maleimide compound), 2-isocyanatoethyl methacrylate (polyfunctional isocyanate compound) 6.8 g of N,N-dimethylcyclohexylamine (urethanization catalyst), 0.001 g of 4-tert-butylpyrocatechol (radical polymerization inhibitor), and 200 g of methyl ethyl ketone (solvent) were collected and sealed. Thereafter, the contents were stirred at room temperature for about 15 hours using a rotary mixer to dissolve the contents, thereby producing a highly insulating resin varnish having a concentration of about 25 wt%.

(3) Preparation of sample for evaluating dielectric breakdown voltage of highly insulating resin The above-mentioned highly insulating resin varnish was applied onto a copper plate having a thickness of 1 mm and a side of 100 mm. The highly insulating resin varnish on the copper plate was then dried in a constant temperature bath at 80° C. for 30 minutes. The dried sample was then heated in a constant temperature bath at 180° C. for 1 hour to cure the highly insulating resin layer and obtain a sample for dielectric breakdown voltage evaluation. According to this procedure, the coating thickness of the highly insulating resin varnish was varied to produce samples having highly insulating resin layers of various thicknesses.

(4) Preparation of Insulating Layer 1A A polyimide film with a thickness of 5 μm and a side of 150 mm was attached to a glass plate with a thickness of 3 mm and a side of 200 mm using a polyimide tape. A highly insulating resin varnish is applied onto the polyimide film, dried at 80°C for 30 minutes, and then heated at 180°C for 1 hour to harden the highly insulating resin layer to obtain an insulating layer 1A having a two-layer structure. Ta. According to this procedure, the coating thickness of the highly insulating resin varnish was changed to produce samples of the insulating layer 1A having various thicknesses of the highly insulating resin layer.

(5) Preparation of Insulating Layer 1B An aramid nonwoven fabric having a thickness of 250 μm, a width of 100 mm, and a length of 100 mm was impregnated with a highly insulating resin varnish by a dipping method. After drying at 80°C for 30 minutes, the part coated with the highly insulating resin varnish was cut out to a size of 100 mm on each side, sandwiched between two end plates that had been subjected to mold release treatment, and pressed under a pressure of approximately 10 torr using a vacuum press machine. It was molded under conditions of 1.5 MPa and a temperature of 180° C., and was cured to produce an insulating layer 1B having an impregnated structure. According to this procedure, samples of the insulating layer 1B having highly insulating resin layers with various thicknesses were prepared by changing the amount of the highly insulating resin varnish impregnated.

(6) Preparation of mold varnish Each component was blended at a predetermined blending ratio and stirred for 3 minutes using an AR-100 type rotation/revolution mixer manufactured by Shinky Co., Ltd. to prepare a varnish. Table 1 in FIG. 12 is a table showing the components and viscosity of the mold varnishes used in Examples and Comparative Examples.

(7) Preparation of mold single layer sample The mold varnish prepared previously was preheated to 60°C. A mold having a casting space with a thickness of 1 mm, a width of 140 mm, and a length of 120 mm was preheated to 80° C., and the mold varnish was poured into the mold and degassed under vacuum. The defoaming conditions were 80° C. and 1 mmHg for 10 minutes. Similarly, the mold varnish was poured into a mold having a casting space of 2 mm thick, 140 mm wide, and 120 mm long, and defoamed under vacuum.

The mold was moved to a constant temperature bath and cured in the atmosphere by two-step heating at 100° C. for 5 hours and 170° C. for 10 hours. The mold was dismantled to produce molded single layer samples with a width of 140 mm, a length of approximately 120 mm, and thicknesses of 1 mm and 2 mm.

(8) Preparation of composite insulating mold samples Samples of film-like insulating layers 1A having various thicknesses were cut into pieces of 100 mm on each side. The cut insulating layer 1A was attached with polyimide tape to the inner wall of a mold having a casting space with a thickness of 1 mm, a width of 140 mm, and a length of 120 mm. Thereafter, the mold was preheated to 80°C, and the mold varnish preheated to 60°C was poured into the mold and degassed under vacuum. The defoaming conditions were 80° C. and 1 mmHg for 10 minutes. The mold was moved to a constant temperature bath and cured in the atmosphere by two-step heating at 100° C. for 5 hours and 170° C. for 10 hours. The mold was dismantled to produce a composite insulating mold sample having a width of 140 mm, a length of about 120 mm, a thickness of 1 mm, and an insulating layer 1A on one side. Composite insulation samples having 1A of insulation layers with different thicknesses of highly insulating resin layers were produced in the same manner.

(4) Measurement of mold varnish viscosity The viscosity of the varnish was measured at 60° C. using an E-type viscometer.

(5) Method for evaluating dielectric breakdown voltage The dielectric breakdown voltage was observed using the previously produced resin plate in accordance with the JIS standard (C2110). A brass spherical electrode with a diameter of 20 mm was used as the electrode to which high voltage was applied, and a SUS flat plate electrode was used as the ground side electrode. A sample film or molded sample was sandwiched between both electrodes, and the test was carried out using a dielectric strength tester (100 kV/10 kA, commercial frequency 50 Hz) manufactured by Tokyo Transformer Co., Ltd. in electrical insulating oil (Florinat, FC-3283). The dielectric breakdown voltage was observed under the conditions of a boost rate of 2 kV/sec and a cut-off current of 8 mA.

FIG. 4 shows the relationship between the film thickness of the highly insulating resin layer 4 formed on the copper plate and the dielectric breakdown voltage. As a result of determining the dielectric breakdown voltage at a thickness of 25 μm by linear approximation, the value was approximately 7.7 kV, which confirmed that the material had high insulation properties as a thin film material. This material system has excellent insulation properties and was suitable as a highly insulating resin.

FIG. 5 shows the relationship between the film thickness and dielectric breakdown voltage of an insulating layer 1A in which a highly insulating resin layer is formed on a polyimide film with a thickness of 5 μm. The dielectric breakdown voltage at a thickness of 25 μm was determined by linear approximation, and the value was approximately 8.2 kV, confirming that the material had high insulation properties for a thin film material. The results showed that the insulating layer 1A, which is a composite insulation of the highly insulating resin layer 4 and the polyimide insulating base material, has a higher dielectric breakdown voltage than the highly insulating resin layer alone. The insulating layer 1A had excellent insulation properties and was suitable as a highly insulating material.

(Comparative example 1)
FIG. 6 shows the relationship between the thickness of the polyimide film and the dielectric breakdown voltage. As a result of calculating the dielectric breakdown voltage at a thickness of 25 μm by linear approximation, the value was approximately 5.9 kV, which indicates that the dielectric breakdown voltage is considered to be lower than that of the high insulating resin and insulating layer 1A used in the present invention. Obtained.

FIG. 7 shows the relationship between the film thickness and dielectric breakdown voltage of the insulating layer 1B, which is an aramid nonwoven fabric impregnated with a highly insulating resin. In addition, the dielectric breakdown voltage of the aramid nonwoven fabric itself is also shown in FIG. Comparing the dielectric breakdown voltages for a thickness of 300 μm determined by linear approximation, the insulating layer 1B was about 14.7 kV, whereas the aramid nonwoven fabric showed about 10.5 kV. The insulating layer 1B, which is a composite of a highly insulating resin and an aramid nonwoven fabric, exhibited a higher dielectric breakdown voltage than the aramid nonwoven fabric, and obtained results that seemed to be suitable as a highly insulating material.

(Comparative example 2)
FIG. 8 shows the relationship between the thickness and dielectric breakdown voltage of the molded single layer sample. The number of observation points was 5, and the average value was recorded. The dielectric breakdown voltage at a thickness of 1 mm was 32 kV, and the dielectric breakdown voltage at a thickness of 2 mm was 45 kV. This value was a dielectric breakdown voltage comparable to that of general mold resin.

Figure 8 also shows the results of observing the dielectric breakdown voltage of a 1 mm thick composite insulation mold sample containing an insulating layer 1A in which the highly insulating resin layer has a thickness of 20 μm and the polyimide film base material has a thickness of 5 μm. . The number of observation points was 5, and the average value was as high as 48 kV/mm, which revealed that the dielectric breakdown voltage was higher than that of the 2 mm thick molded single layer sample.

Compared to a 1 mm thick molded single layer sample, the molded sample with composite insulation structure had a 50% increase in breakdown voltage. The above results suggest that by adopting a composite insulation structure in molded electrical equipment, the insulation layer can have a higher withstand voltage, and based on this, it is possible to make the insulation layer thinner and make the equipment smaller and lighter. It was done.

Figure 8 also shows the results of observing the dielectric breakdown voltage of a 1 mm thick composite insulating mold sample containing an insulating layer 1A in which the highly insulating resin layer has a thickness of 50 μm and the polyimide film base material has a thickness of 5 μm. . The number of observation points was 5, and the average value showed 50 kV. A comparison with Example 4 confirmed that thickening the insulating layer 1A contributed to further increasing the withstand voltage of the mold sample having the composite insulating structure. The adoption of a molded electrical device with a composite insulation structure having a thick insulation layer 1A contributes to the thinning of the insulation layer based on the higher voltage resistance of the insulation layer, and to the miniaturization and weight reduction of the device.

A total of 21 kg of an insulating layer 1 having a 25 μm thick highly insulating resin layer on both sides of a 50 μm thick polyimide film serving as an insulating base material and a mold varnish shown in Table 1 (FIG. 12) were prepared. An insulating layer 1 was wound around a primary coil 6, a shield coil 7, and a secondary coil 8, which are built-in parts of a molded transformer.

Next, built-in parts such as a coil and electrodes were assembled into a predetermined mold, and the mold was preheated to 80°C. Approximately 21 kg of mold varnish preheated to 60° C. was defoamed at 1 mmHg for 15 minutes, then poured into the mold, and vacuum defoamed at 3 mmHg for 15 minutes. This mold was cured in the atmosphere by two-stage heating at 80° C. for 20 hours and 140° C. for 10 hours, and was naturally cooled in an oven overnight. No cracks occurred in the simulated molded transformer from which the mold was removed, and it was confirmed that the insulating layer 1 could be installed inside the molded resin layer.

As described above, a simulated molded transformer including the insulating layer 1 that contributes to increasing the voltage resistance of the molded resin layer shown in FIG. 9 can be manufactured.

A total of 31.5 kg of insulating layer 1 having a 25 μm thick highly insulating resin layer on both sides of a 50 μm thick polyimide film serving as an insulating base material and mold varnish shown in Table 1 (FIG. 12) was prepared. . The insulating layer 1 was wound around an electric field relaxation shield 9, which is one of the built-in components of the switch and is subjected to a high electric field.

Various parts were assembled into a mold for forming a simulated solid insulation switch, and the mold was preheated to 80°C. After preheating 31.5 kg of mold varnish to 60°C and defoaming at 1 mmHg for 15 minutes, the mold varnish was vacuum cast into the mold at 3 mmHg and 80°C. Thereafter, it was cured in two stages: 80°C/20 hours in the atmosphere and 140°C/10 hours, and naturally cooled in an oven overnight. No cracks occurred in the simulated solid insulated switchgear from which the mold was removed, and it was confirmed that the insulating layer 1 could be installed inside the molded resin layer.

As described above, it is possible to produce a simulated solid insulated switch including the insulating layer 1 shown in FIG. 10, which contributes to increasing the withstand voltage of the molded resin layer.

Example 8 is an example in which the highly insulating resin layer of the above-mentioned example was formed on a winding wire having a polyimide enamel layer with a thickness of 50 μm on the surface of the core wire 15, which is a conductor. In this example, a highly insulating resin varnish was applied to the surface of a polyimide enamel layer with a thickness of 50 μm using a die, dried at 80°C for 30 minutes, and heated at 180°C for 1 hour to achieve high insulation. The resin layer was cured.

The thickness of the highly insulating resin layer after drying and curing was 20 μm. A schematic cross-sectional view of a winding wire having a highly insulating resin layer is shown in FIG. From a comparison between Example 2 and Comparative Example 1, the breakdown voltage of the winding having the present composite insulation structure is higher than that of the winding having the polyimide enamel layer. By applying the winding of this example to the coil of a molded transformer, or the stator or rotor of a motor in which the winding is fixed with a fixing varnish, it is expected that the withstand voltage of the molded electrical equipment will be even higher.

As explained above, according to this example, a molded electrical device with improved breakdown voltage of the insulating layer can be produced without impairing the castability, fracture toughness, low thermal expansion, and heat resistance of conventional mold varnish. It has been shown that it can be provided.

DESCRIPTION OF SYMBOLS 1... Insulating layer, 2... Built-in component, 3... Insulating base material, 4... Highly insulating resin layer, 5... Molding resin layer, 6... Primary coil, 7... Shield coil, 8... Secondary coil, 9... Electric field Relaxation shield, 10... Fixed electrode, 11... Vacuum valve, 12... Bellows, 13... Operating electrode, 14... Metal electrode (bushing), 15... Core wire, 16: Enamel layer

Claims (9)

a mold resin layer;
an insulating layer;
The insulating layer is
A phenoxy resin or epoxy resin having multiple alcoholic hydroxyl groups in the side chain,
A polyfunctional monomer having at least one functional group selected from the group consisting of a vinyl group, an acrylate group, and a methacrylate group and one isocyanate group;
A highly insulating resin having a mixture and/or reaction product with a maleimide compound having multiple maleimide groups in its structure ,
A molded electrical device in which the insulation layer has a higher dielectric breakdown voltage than the molded resin layer at the same thickness . The molded electrical device according to claim 1,
The thickness of the insulating layer is
A molded electrical device that is thinner than the molded resin layer . The molded electrical device according to claim 1,
The insulating layer is
The highly insulating resin;
A molded electrical device that is a composite material having a multilayer structure or an impregnated structure with a film, porous, woven, or nonwoven insulating substrate . The molded electrical device according to claim 3 ,
The insulating base material is
A molded electrical device containing any one of polyimide resin, polyamideimide resin, polyesterimide resin, aramid resin, liquid crystal polymer, and cellulose . The molded electrical device according to claim 1 ,
The mold resin layer is
A molded electrical device that is a cured product of an epoxy resin composition containing crushed silica and fused silica . The molded electrical device according to claim 1,
Molded electrical equipment with built-in components . The molded electrical device according to claim 6 ,
The built-in parts are
Molded electrical equipment with primary coil, shield coil, and secondary coil . The molded electrical device according to claim 6 ,
The built-in parts are
Molded electrical equipment that is an electric field mitigation shield . The molded electrical device according to claim 1 ,
A molded electrical device in which a coil is formed of a winding having the insulating layer .

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