JP2015101714A - Nonlinear resistance resin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonlinear resistance resin material capable of uniformly dispersing a filler in a matrix resin and obtaining excellent nonlinear resistance characteristics.SOLUTION: A nonlinear resistance resin material 20 comprises: a matrix resin 22 consisting of a liquid epoxy resin; ZnO containing particles 21 dispersed and included in matrix resin 22 and consisting of a sintered body having zinc oxide as a principal component; semiconductive whiskers 10 dispersed and included in the matrix resin 22 and consisting of zinc oxide; and a self-polymerization catalyst added to the matrix resin 22 and promoting the self-polymerization of the epoxy resin.

Description

  Embodiments described herein relate generally to a non-linear resistance resin material.

  Generally, in a high voltage device used for a power system or the like, an electric field relaxation technique for suppressing local electric field concentration is used. As one conventional electric field relaxation method for a high electric field portion, a non-linear resistance resin material is applied to the inner wall surface of a high voltage device.

  This non-linear resistance resin material is constituted by dispersing a varistor powder mainly composed of zinc oxide (ZnO) having current-voltage non-linear resistance characteristics in a polymer matrix which is an insulating material.

  In order to improve the non-linear resistance characteristic in the non-linear resistance resin material, it has been studied to further mix a semiconductive substance such as ZnO whisker. Moreover, in order to disperse | distribute ZnO whisker uniformly, performing the silane coupling process on the surface of ZnO whisker is examined. In this technique, a semiconductive material is blended to secure a conductive path of the varistor powder and prevent sedimentation of the varistor powder.

JP 2012-142377 A

  However, in conventional non-linear resistance resin materials, ZnO whiskers that have been subjected to silane coupling treatment as an additive may aggregate due to the addition of a diluting solvent. As a result, sedimentation of the varistor powder cannot be sufficiently prevented, and the original non-linear resistance characteristic may not be exhibited. Further, by adding a curing agent for curing the matrix resin of the non-linear resistance resin material, uniform dispersion of ZnO whiskers may not be obtained.

  The problem to be solved by the present invention is to provide a non-linear resistance resin material in which excellent non-linear resistance characteristics can be obtained by uniformly dispersing a filler in a matrix resin.

  The non-linear resistance resin material of the embodiment includes a matrix resin made of a liquid epoxy resin, dispersed particles in the matrix resin, particles made of a sintered body mainly composed of zinc oxide, and dispersed in the matrix resin. And a semiconductive whisker made of zinc oxide and a self-polymerization catalyst which is added to the matrix resin and promotes self-polymerization of the epoxy resin.

It is the perspective view which showed typically the semiconductive whisker which consists of ZnO which the nonlinear resistance resin material of embodiment contains. It is the figure which showed typically the structure of the nonlinear resistance resin material of embodiment, in order to demonstrate the conductive path which a ZnO containing particle | grain and a whisker form. It is the figure which showed the electric equipment with which the non-linear resistance film was formed using the non-linear resistance resin material of embodiment in the partial cross section. It is a figure which shows the cross section of the test member which evaluates a nonlinear resistance characteristic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The non-linear resistance resin material of the embodiment includes a matrix resin made of an epoxy resin, particles made of a sintered body mainly composed of zinc oxide (ZnO), and semiconductive whiskers made of zinc oxide (ZnO). Is dispersed and contained. A self-polymerization catalyst that promotes self-polymerization of the epoxy resin is added to the matrix resin. Note that the epoxy resin before being cured is in a liquid state.

  The epoxy resin constituting the matrix resin is composed of an epoxy compound having two or more epoxy groups per molecule. As such an epoxy compound, any compound that has two or more three-membered rings of two carbon atoms and one oxygen atom in one molecule and is curable can be used as appropriate. It is not particularly limited.

  The epoxy resin used here is one that self-polymerizes and cures when heated without adding a curing agent, and one that self-polymerizes and cures when irradiated with visible light or ultraviolet light. . These epoxy resins are in a liquid state around room temperature (for example, 25 ° C.).

  First, an epoxy resin that self-polymerizes and cures when heated will be described.

  The epoxy resin is not particularly limited, and any monomer, oligomer, or polymer can be used as long as it has one or more epoxy groups in the molecule. Examples of the epoxy resin include conventionally known aliphatic epoxy resins, alicyclic epoxy resins, and aromatic epoxy resins. Typical examples of these epoxy resins include bisphenol A type epoxy resins, polyglycidyl ethers of polyhydric alcohols, polyglycidyl esters, epoxidized phenol novolac resins, epoxidized polyolefins, and alicyclic epoxy compounds. Can be mentioned. Specific examples include alkylene oxides such as ethylene oxide, propylene oxide, 1,2-epoxybutane, butadiene monooxide, epoxy hexane, epoxy octane, epoxy decane, epoxy hexadecane, and epoxy octadecane. Specific examples include compounds having an epoxy group such as epoxy hexene and epoxy octene and a double bond unsaturated group. Specifically, one epoxy group is included in a molecule such as a compound having a glycidyl group such as glycidyl methyl ether, glycidyl isopropyl ether, glycidyl butyl ether, glycidyl acrylate, glycidyl methacrylate, monoglycidyl ether of higher aliphatic alcohol. Including compounds. Specific examples thereof include compounds having two or more epoxy groups in the molecule, such as diglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof.

  In addition, the epoxy resin hardened | cured by the above-mentioned heating can be used even if it is single 1 type or in combination of 2 or more types.

  Next, an epoxy resin that self-polymerizes and cures when irradiated with visible light or ultraviolet light will be described.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, and alicyclic epoxy resin. Examples of the bisphenol A type epoxy resin include Adekaoptomer KRM-2524 and Adekaoptomer KRM-2400 (Asahi Denka). Examples of the bisphenol F-type epoxy resin include Adekaoptomer KRM-2490 (manufactured by Asahi Denka). Examples of the phenol novolac type epoxy resin include Adeka optomer KRM-2604 (manufactured by Asahi Denka). Examples of the alicyclic epoxy resin include Celoxide 2021A and Celoxide 2021P (manufactured by Daicel UCB) which are 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

  In addition, the epoxy resin hardened | cured by irradiation of the above-mentioned visible light or an ultraviolet-ray can be used even if it is single 1 type or in combination of 2 or more types.

  Next, a self-polymerization catalyst that promotes self-polymerization will be described.

  The self-polymerization catalyst that promotes self-polymerization by heating is composed of, for example, a boron trifluoride-amine complex, an aliphatic sulfonium salt, an imidazole compound, or the like.

  Examples of the boron trifluoride-amine complex include boron trifluoride-monoethylamine complex, boron trifluoride-benzylamine complex, boron trifluoride-aniline complex, boron trifluoride-chloroaniline complex, and the like. . Examples of the boron trifluoride-amine complex include 2285B, 2287, 2287B (manufactured by Three Bond). Examples of the boron trifluoride-aniline complex include anchor 1171 (manufactured by Anchor Chemical Co., Ltd.). Examples of the boron trifluoride-chloroaniline complex include anchor 1170 (manufactured by Anchor Chemical Co., Ltd.).

  Examples of the aliphatic sulfonium salts include trialkylsulfonium salts, tribenzylsulfonium salts, dimethylbenzylsulfonium salts, and the like. As the aliphatic sulfonium salt, specifically, for example, Adekaoptomer CP-66, Adekaoptomer CP-77 (manufactured by ADEKA) and the like can be used.

  Examples of the imidazole compound include 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. Specifically as an imidazole compound, for example, Curesol 2E4MZ (manufactured by Shikoku Kasei Co., Ltd.) (2-ethyl-4-methylimidazole) and the like can be used.

  Here, the self-polymerization catalyst that promotes self-polymerization by heating is preferably added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin (matrix resin). The range of the addition amount is preferable because a cured product having excellent electrical characteristics, mechanical characteristics, and heat resistance can be obtained. The self-polymerization catalyst is more preferably added in an amount of 3 to 15 parts by mass with respect to 100 parts by mass of the epoxy resin (matrix resin).

  The epoxy resin that self-polymerizes when heated as described above is cured, for example, by heating at a temperature of 60 to 180 ° C, preferably 80 to 150 ° C, with the self-polymerization catalyst promoting self-polymerization.

  The self-polymerization catalyst that promotes self-polymerization by irradiation with visible light or ultraviolet light is composed of, for example, an aromatic sulfonium salt, an aromatic diazonium salt, or the like.

  Examples of aromatic sulfonium salts include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, and bis [4- (diphenyl). Sulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthale Nylsulfonium hexafluorophosphate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthalenylsulfonium hexafluoroatimonate, and the like. Specific examples of the aromatic sulfonium salt include OPTOMER SP-150, SP-170 (Asahi Denka), UVI series (UCC), UVE series (GE), FC series and FX series ( 3M) and the like can be used.

  Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis (pentafluorophenyl) borate. Specific examples of the aromatic diazonium salt include ULTRASET (manufactured by ADEKA), AMERICURE (manufactured by American), and the like.

  Here, the self-polymerization catalyst for promoting self-polymerization by irradiation with visible light or ultraviolet light is preferably added in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin. By blending 0.5 parts by mass or more of the self-polymerization catalyst with respect to 100 parts by mass of the epoxy resin, sufficient mechanical strength and adhesive strength are given to the epoxy resin. On the other hand, when the amount of the self-polymerization catalyst is increased, the ionic substance in the cured product is increased, so that the hygroscopic property of the cured product is increased and the mechanical strength and the adhesive strength are decreased. Therefore, a self-polymerization catalyst shall be 10 mass parts or less with respect to 100 mass parts of epoxy resins. Moreover, it is more preferable that 1-5 mass parts of self-polymerization catalysts are added with respect to 100 mass parts of epoxy resins.

  The above-mentioned epoxy resin that self-polymerizes when irradiated with visible light or ultraviolet light, for example, is cured by being accelerated by self-polymerization catalyst by irradiation with visible light or ultraviolet light. Here, the ultraviolet light preferably has a wavelength of 250 nm to 380 nm.

  The above self-polymerization catalyst is appropriately selected and used depending on the epoxy resin used and the application.

  Next, the particle | grains which consist of a sintered compact which has ZnO as a main component are demonstrated.

Particles made of a sintered body containing ZnO as a main component (hereinafter referred to as ZnO-containing particles) have non-linear resistance characteristics. The sintered body is sintered by including at least one kind of metal oxide such as Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , NiO as a subsidiary component, and is formed into a spherical shape or a substantially spherical shape. Has been. The sintered body is an aggregate formed by sintering a structure showing a structure in which conductive ZnO particles are surrounded by an insulating grain boundary layer. Since the non-linear resistance characteristic is generated at the grain boundary of the conductive ZnO particles surrounded by the insulating grain boundary layer, the individual particles themselves of the sintered body have non-linear resistance characteristics.

Here, it is preferable that the mixture before sintering which comprises a sintered compact contains 94 mol% or more of zinc oxides, for example. Further, the mixture, as a secondary component, for example, bismuth, antimony, manganese, cobalt, respectively nickel _{Bi 2 O 3, Sb 2 O} 3, MnO, in terms of _Co 2 O 3, NiO, and _Bi 2 _{O 3} 0.3~0.8mol%, _Sb 2 _{O 3} to 0.95~1.75mol%, 0.6~1.2mol% of MnO, 0.5~1.6mol% of _Co 2 _{O 3,} the NiO It is preferable to contain 0.95-1.75 mol%.

  In addition, content of a subcomponent is not restricted to this, It can adjust suitably. Further, here, an example in which bismuth, antimony, manganese, cobalt, and nickel are included as subcomponents is shown, but as described above, at least one of these metal oxides may be included as subcomponents. .

  The average particle diameter of the ZnO-containing particles is preferably 10 μm to 100 μm in order to ensure workability such as painting while exhibiting non-linear resistance characteristics with the ZnO-containing particles alone. Among these ranges, those having an average particle diameter of 30 μm to 80 μm that further improve the non-linear resistance characteristic are more preferable.

  Here, the average particle diameter is calculated by, for example, observing a cross section of a predetermined resin containing dispersed ZnO-containing particles with an SEM (scanning electron microscope), measuring the particle diameter of each ZnO-containing particle, Obtained by averaging.

  The content of the ZnO-containing particles is 40 to 90 parts by mass with respect to 100 parts by mass of the epoxy resin (matrix resin) in order to ensure workability such as formation of a conductive path and coating in the non-linear resistance resin material. Is preferred. Moreover, as for content of ZnO containing particle | grains, it is more preferable that it is 50-70 mass parts with respect to 100 mass parts of epoxy resins.

  Next, a semiconductive whisker made of ZnO will be described. FIG. 1 is a perspective view schematically showing a semiconductive whisker 10 made of ZnO contained in the nonlinear resistance resin material of the embodiment. The whisker 10 is not subjected to silane coupling treatment or titanate coupling treatment.

  As shown in FIG. 1, the whisker 10 has a tetrapot shape including a core portion 11 and needle crystal portions 12 extending from the core portion 11 in the four-axis direction. The specific resistance of the whisker 10 that is semiconductive is 1 to 5000 Ω · cm.

  In the matrix resin, the length L of the needle-like crystal part 12 of the whisker 10 is 2 μm to 50 μm and the needle-like crystal part 12 has a length L so that the whisker 10 connects the ZnO-containing particles to form a good conductive path. The average diameter D (arithmetic average diameter) of the portion having the maximum diameter is preferably 0.2 μm to 3.0 μm. As a semiconductive whisker made of ZnO, for example, Panatetra (manufactured by Amtec Corporation) can be used.

  In the matrix resin, the whisker 10 connects ZnO-containing particles to form a good conductive path, and in order to ensure workability such as painting, the whisker 10 is used with respect to 100 parts by mass of the epoxy resin (matrix resin). It is preferable to contain 5-30 mass parts.

  Here, FIG. 2 is a diagram schematically showing the configuration of the non-linear resistance resin material 20 of the embodiment in order to explain the conductive path 23 formed by the ZnO-containing particles 21 and the whiskers 10.

  As shown in FIG. 2, the whisker 10 enters between the ZnO-containing particles 21 and uniformly disperses the ZnO-containing particles 21 in the matrix resin 22. Thereby, the non-linear resistance characteristic expressed by the ZnO-containing particles 21 can be improved. In addition, the whisker 10 contacts the ZnO-containing particles 21 and electrically connects the ZnO-containing particles 21 to form a three-dimensional conductive path 23.

  Here, in order to electrically connect the ZnO-containing particles 21 to form a conductive path, for example, a particle made of a low resistance material such as carbon may be added instead of the whisker 10. It is inappropriate because it leads to On the other hand, dielectric breakdown or the like can be prevented by using the semiconductive whisker 10 described above.

  Next, the manufacturing method of the nonlinear resistance resin material 20 of embodiment is demonstrated.

  First, a predetermined amount of a self-polymerization catalyst is added to and mixed with the epoxy resin to be blended. A part of the epoxy resin to which the self-polymerization catalyst is added (for example, about 10 to 50% by mass of the total amount of the epoxy resin) and a predetermined amount of whisker 10 are agitated by a rotating / revolving mixer or the like to prepare a master batch. .

  Subsequently, the remainder of the epoxy resin to which the self-polymerization catalyst is added and a predetermined amount of the ZnO-containing particles 21 are added to the master batch, and the mixture is stirred by a rotation and revolution mixer or the like.

  The non-linear resistance resin material 20 is manufactured through such steps.

  Thus, the whisker 10 can be uniformly disperse | distributed in the non-linear resistance resin material 20 by producing the masterbatch containing the whisker 10 and mixing the remaining component in this masterbatch. By uniformly dispersing the whisker 10, the sedimentation of the ZnO-containing particles 21 can be suppressed, and a good conductive path 23 can be formed.

  For example, when producing a cast cured product from the liquid non-linear resistance resin material 20 produced as described above, first, the non-linear resistance resin material 20 is, for example, injected into a mold and molded. And when using the epoxy resin which self-polymerizes by heating, self-polymerization is accelerated | stimulated and hardened | cured by a self-polymerization catalyst by heating at predetermined temperature for predetermined time. On the other hand, when using an epoxy resin that self-polymerizes when irradiated with visible light or ultraviolet light, the self-polymerization catalyst accelerates self-polymerization and cures by irradiating visible light or ultraviolet light for a predetermined time.

  Here, by irradiating visible light or ultraviolet rays, the epoxy resin is cured to obtain almost practical characteristics, but may be further heated after being irradiated with visible light or ultraviolet rays. By applying this heat treatment, durability such as adhesion and water resistance is remarkably improved. The heat treatment is performed at a temperature of 80 to 150 ° C., for example.

  When a non-linear resistance film is formed from the liquid non-linear resistance resin material 20, for example, the non-linear resistance resin material 20 is first applied to the structure by, for example, applying with a brush or airless spray. And it hardens | cures by heating or irradiation with visible light or an ultraviolet-ray similarly to the case where the above-mentioned cast hardened | cured material is manufactured.

  When forming a non-linear resistance film, the non-linear resistance film should be thicker from the viewpoint of manifesting non-linear resistance characteristics, and can be applied to a thickness of about 500 μm from the viewpoint of coating workability. is there.

  FIG. 3 is a partial cross-sectional view of an electric device in which the non-linear resistance film 34 is formed using the non-linear resistance resin material 20 of the embodiment. Note that FIG. 3 shows a hermetic insulating device 30 as an example of an electric device.

  As shown in FIG. 3, the hermetic insulation device 30 is provided between a metal container 31 and a cylindrical metal container 31 that can be divided into a plurality of parts in the axial direction, a high-voltage conductor 32 that is arranged in the center in the axial direction. The spacer 33 is provided.

The spacer 33 is disposed so as to divide the inside of the metal container 31 in a direction perpendicular to the central axis of the cylinder. Further, the inner peripheral surface of the metal container 31 is provided with a non-linear resistance film 34 formed using the non-linear resistance resin material 20 of the present embodiment. An insulating gas 35 such as SF ₆ gas is sealed in the metal container 31.

  As described above, the non-linear resistance film 34 made of the non-linear resistance resin material 20 capable of obtaining good non-linear resistance characteristics is provided on the inner peripheral surface of the metal container 31, so that it exists on the surface layer of the non-linear resistance film 34. The movement of foreign matter can be suppressed. Therefore, the design electric field of the metal container can be increased as compared with the conventional hermetic insulation device, and the metal container 31 can be made compact.

  Here, the sealed insulation device is shown and described as an example of the electric device. However, the non-linear resistance resin material of the embodiment may be various electric devices, electronic devices, industrial devices, heavy electric devices, for example. Etc. And even when applied to these, the same effect as mentioned above can be obtained.

  As described above, according to the non-linear resistance resin material 20 of the embodiment, the matrix resin 22 is an epoxy resin that is cured by heating, or an epoxy resin that is cured by irradiation with visible light or ultraviolet light. By adding a self-polymerization catalyst that promotes self-polymerization to the resin 22, it becomes unnecessary to use a curing agent that deteriorates the dispersibility of the ZnO-containing particles 21 and the whisker 10. As a result, by uniformly dispersing the ZnO-containing particles 21 and the whisker 10 in the matrix resin 22, a good conductive path 23 can be secured. Thereby, excellent non-linear resistance characteristics can be obtained.

(Evaluation of non-linear resistance characteristics)
Next, the fact that the non-linear resistance resin material of the embodiment has excellent non-linear resistance characteristics will be described.

  In order to evaluate the non-linear resistance characteristics, a non-linear resistance resin material 20 was produced as follows.

  First, a self-polymerization catalyst was mixed with the epoxy resin to be blended to prepare an epoxy resin in which five different self-polymerization catalysts were mixed. Here, as an epoxy resin, a bisphenol A type epoxy resin (DGEBA) (trade name JER828: epoxy equivalent 190) having both a property of being cured by heating and a property of being cured by irradiation with visible light or ultraviolet light is used. used.

  As the self-polymerization catalyst for promoting curing by heating, as shown in Table 1, 2285B (manufactured by Three Bond) as a boron trifluoride-amine complex, and Adekaoptomer CP-66 (Asahi Denka) as an aliphatic sulfonium salt are used. Cureazole 2E4MZ (manufactured by Shikoku Kasei Co., Ltd.) was used as the imidazole compound. As shown in Table 1, as a self-polymerization catalyst that promotes curing by visible light or ultraviolet light, OPTOMER SP-150 (Asahi Denka Co., Ltd.) is used as an aromatic sulfonium salt, and ULTRASET (Adeka Co., Ltd.) is used as an aromatic diazonium salt. It was used. The content of the above self-polymerization catalyst was 3 parts by mass with respect to 100 parts by mass of the epoxy resin.

  Subsequently, whisker 10 is added to a part of each epoxy resin mixed with the self-polymerization catalyst (for example, 50% by mass of the total blended amount of the epoxy resin mixed with the self-polymerization catalyst) and stirred by a rotation and revolution mixer or the like. A master batch was prepared. Here, when the total blending amount of epoxy resin (total blending amount of epoxy resin in a state where no self-polymerization catalyst is mixed) is added, whisker 10 becomes 10 parts by mass with respect to 100 parts by mass of epoxy resin. Whisker 10 was added. As the semiconductive whisker 10 made of ZnO, one having a length L of the needle-like crystal part 12 of 2 μm to 50 μm and an average diameter D of the part having the maximum diameter of the needle-like crystal part 12 of 3 μm was used.

Subsequently, the remainder of each epoxy resin and a predetermined amount of ZnO-containing particles 21 were added to the master batch, and the mixture was stirred by a rotation and revolution mixer or the like. Here, the ZnO-containing particles 21 are composed of a sintered body containing ZnO as a main component and Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , and NiO metal oxides as subcomponents. Particles were used. Here, constituting the sintered body, the mixture before sintering, the _{Bi 2 O 3 0.5mol%, Co} 2 O 3 and 0.9 mol%, 0.8 mol% of MnO, the _Sb 2 _{O 3} 1 .2 mol%, NiO 1.1 mol% was used, and the balance was ZnO.

  The average particle diameter of the ZnO-containing particles 21 was 30 μm. Moreover, content of the ZnO containing particle | grains 21 was 50 mass parts with respect to 100 mass parts of epoxy resins (total compounding quantity of the epoxy resin in the state in which the self-polymerization catalyst is not mixed).

  In this manner, five types of non-linear resistance resin materials 20 of Sample 1 to Sample 5 shown in Table 1 were produced.

For comparison, in addition to the five types of non-linear resistance resin materials 20 described above, Samples 6 and 7 containing different curing accelerators and containing a curing agent were prepared. In Sample 6 and Sample 7, as shown in Table 1, a quaternary ammonium salt (Nissan cation M ₂ -100; manufactured by NOF Corporation) as a curing catalyst was used. The content of the curing accelerating catalyst was 3 parts by mass with respect to 100 parts by mass of the epoxy resin, as in Samples 1 to 5.

  The epoxy resin, whisker 10, and ZnO-containing particles 21 used for Sample 6 and Sample 7 were also the same as Sample 1 to Sample 5. The contents of the whisker 10 and the ZnO-containing particles 21 were also the same as those of the samples 1 to 5.

  On the other hand, in sample 6, acid anhydride (Me-HHPA; methylhexahydrophthalic anhydride) is used as a curing agent with respect to epoxy resin (total amount of epoxy resin in a state where no curing accelerating catalyst is mixed). It contained 86 parts by mass. In Sample 7, 80 parts by mass of acid anhydride (Me-THPA; methyltetrahydrophthalic anhydride) as a curing agent with respect to the epoxy resin (total amount of epoxy resin in a state where no curing accelerating catalyst is mixed) Contained.

  The manufacturing method of Sample 6 and Sample 7 was the same as Sample 1 to Sample 5, and the curing agent was added when adding the remainder of each epoxy resin and a predetermined amount of ZnO-containing particles 21 to the masterbatch.

  Next, the test member 100 which evaluates a non-linear resistance characteristic was produced as follows using the above-mentioned sample 1 to sample 7. FIG. 4 is a diagram showing a cross section of the test member 100 for evaluating the non-linear resistance characteristic.

  First, on one surface 41a of an aluminum plate 41 having a thickness of 3 mm, a length of 70 mm, and a width of 70 mm, a Teflon (registered trademark) having a hole with a diameter of 60 mm in the center and a thickness of 130 μm is installed. Masking was performed. Subsequently, samples (Sample 1 to Sample 7) were applied to the center hole of Teflon.

  Here, in the samples 1 to 3 which are cured by heating, the nonlinear resistance layer 42 is formed by heating at a temperature of 100 ° C. for 15 hours. Samples 4 to 5 that were cured by irradiation with visible light or ultraviolet light were primarily cured by irradiation with ultraviolet light for 10 minutes using a high-pressure mercury lamp. The wavelength range of ultraviolet rays from this high pressure mercury lamp was 250 nm to 380 nm. Then, in order to further increase the mechanical strength and adhesive strength of the sample, the sample was further heated at a temperature of 100 ° C. for 15 hours to form the nonlinear resistance layer 42. In Sample 6 and Sample 7 to which the curing agent was added, the non-linear resistance layer 42 was formed by heating at a temperature of 100 ° C. for 15 hours. The non-linear resistance layer 42 was formed with a diameter of 60 mm and a thickness of 100 μm.

  Subsequently, a conductive paste is applied to the surface of the non-linear resistance layer 42 to form a circular electrode 43 having a diameter of 38 mm, and an electrode 44 having an outer diameter of 50 mm with a gap of 1 mm around the electrode 43. Was made. The other surface 41b of the aluminum plate 41 functioned as an electrode. Here, the electrode 44 and the other surface 41b of the aluminum plate 41 are ground electrodes. After the electrode formation, Teflon was removed.

  Seven types of test members were produced through the above-described steps. A non-linear resistance characteristic was evaluated by applying an electric current to the electrodes of these test members in the range of 0.06 to 0.6 mA using an AC power source. Table 1 shows the result of the evaluation test of the non-linear resistance characteristic in each sample.

  Here, the non-linear index α was used as a criterion for evaluating the non-linear resistance characteristic. The larger the non-linear index α, the better the non-linear resistance characteristic. The criterion that the nonlinear resistance characteristic is expressed is that the nonlinear index α is 5 or more.

The non-linear index α was evaluated at two electric field values at a measurement current of 0.10 mA and 0.60 mA. When the relationship between the current value (I 1), the electric field value (E 1), and the non-linear index α is expressed using the constant (K 1), the following expression (1) is obtained.

Equation (1) can be transformed as equation (2). Formula (3) is obtained by transforming logarithm on both sides of Formula (2).

In Formula (2) and Formula (3), when the measured current value is 0.10 mA, the current density is I ₁ (A / m ² ), the electric field is E ₁ (V / m), and the measured current value is 0.00. The current density at 60 mA was I ₂ (A / m ² ) and the electric field was E ₂ (V / m). The non-linear index α was calculated using the above equation (3).

  Moreover, the presence or absence of aggregation of the whisker 10 after hardening the non-linear resistance resin material 20 was investigated. Whether or not the whisker 10 is aggregated was determined by observing a cross section (cross section in the thickness direction) of the non-linear resistance layer 42 of the test member described above. The cross section was observed at a magnification of 500 times using a scanning electron microscope (SEM).

  Here, the presence / absence of aggregation was judged to be present when there was even one aggregate of whisker 10 having a diameter of 50 μm or more in multiple cross-sectional observations. In other cases, it was judged that there was no aggregation. Table 1 also shows the result of whether or not the whisker 10 is aggregated.

  As shown in Table 1, Sample 1 to Sample 5 had a nonlinear index α of 5 or more, and there was no aggregation of whiskers 10. On the other hand, Sample 6 to Sample 7 had a non-linear index α smaller than 5, and the whisker 10 was aggregated.

  From these results, it can be seen that in the samples 1 to 5, the whisker 10 is uniformly dispersed in the matrix resin 22 and is excellent in non-linear resistance characteristics. On the other hand, it can be seen that in Samples 6 to 7, the whisker 10 aggregates in the matrix resin 22 and is inferior in non-linear resistance characteristics.

  According to the embodiment described above, it is possible to uniformly disperse the filler in the matrix resin and obtain excellent non-linear resistance characteristics.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Whisker, 11 ... Core part, 12 ... Acicular crystal | crystallization part, 20 ... Nonlinear resistance resin material, 21 ... ZnO containing particle | grains, 22 ... Matrix resin, 23 ... Conductive path, 30 ... Sealing type insulation apparatus, 31 ... Metal Container, 32 ... High voltage conductor, 33 ... Spacer, 34 ... Non-linear resistance film, 35 ... Insulating gas, 41 ... Aluminum plate, 41a, 41b ... Surface, 42 ... Non-linear resistance layer, 43,44 ... Electrode, 100 ... Test member.

Claims (8)

A matrix resin made of a liquid epoxy resin;
Particles dispersed in the matrix resin and made of a sintered body containing zinc oxide as a main component;
A semiconductive whisker made of zinc oxide and dispersed in the matrix resin;
A non-linear resistance resin material comprising a self-polymerization catalyst which is added to the matrix resin and promotes self-polymerization of the epoxy resin.   The non-linear resistance resin material according to claim 1, wherein the epoxy resin is self-polymerized and cured by being heated.   The non-linear resistance resin material according to claim 1, wherein the epoxy resin is cured by self-polymerization when irradiated with visible light or ultraviolet light.   The non-linear resistance resin material according to claim 2, wherein the self-polymerization catalyst that promotes self-polymerization by heating is a boron trifluoride-amine complex.   The non-linear resistance resin material according to claim 2, wherein the self-polymerization catalyst that promotes self-polymerization by heating is an aliphatic sulfonium salt.   The non-linear resistance resin material according to claim 2, wherein the self-polymerization catalyst that promotes self-polymerization by heating is an imidazole compound.   The non-linear resistance resin material according to claim 3, wherein the self-polymerization catalyst that promotes self-polymerization by irradiation with visible light or ultraviolet light is an aromatic sulfonium salt.   4. The nonlinear resistance resin material according to claim 3, wherein the self-polymerization catalyst that promotes self-polymerization by irradiation with visible light or ultraviolet light is an aromatic diazonium salt.

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