JP2020050828A - Epoxy resin composition for cast, and ignition coil - Google Patents

Abstract

To provide an epoxy resin composition for cast good in impregnation property into a coil, having excellent insulation property sufficiently applicable to an ignition coil application, excellent in dispersibility of an inorganic filler and a coloring agent, and capable of sufficiently preventing decoloration property under standing at high temperature, and an ignition coil having high credibility.SOLUTION: There is provided an epoxy resin composition for cast containing (A) an epoxy resin, (B) acid anhydride, (C) metal hydroxide, (D) an inorganic filler (excluding the (C) metal hydroxide), (E) a curing promoter, and (F) a coloring agent, in which added moisture amount of the (C) metal hydroxide is 0.1 to 0.5 mass%, and the (F) coloring agent is at least one functional group selected from a group consisting of an amino group, an alkyl amino group, an imino group, an azo group, a nitro group, a cyano group, an amide group, an alkoxy group, a thiol group, and a hydroxy group.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition for casting and an ignition coil.

  2. Description of the Related Art Conventionally, epoxy resin compositions having high impregnation and good electrical insulation have been frequently used for coil insulation treatment. For example, an acid anhydride-curable epoxy resin composition is excellent in mechanical properties at high temperatures, electrical insulation properties, and withstand voltage properties (for example, see Patent Document 1).

  In recent years, in a coil used for an automobile device and the like, particularly in an ignition coil, a high voltage is applied, so that a demand for dielectric breakdown is increased, and a long-term reliable epoxy resin composition and a cured product thereof are required. .

  As a method of improving the dielectric breakdown strength, a large amount of silica is added to the epoxy resin composition to bypass the dielectric breakdown (electric tree) path that goes straight in the resin on the silica surface, thereby increasing the extension distance. There is a method of increasing or preventing the extension path by using a plate-like filler. However, when a large amount of the inorganic filler is added to the epoxy resin composition, the inorganic filler is settled at the time of curing, so that the uniformity of the epoxy resin composition is deteriorated and the reliability may be reduced. As a method of suppressing the sedimentation of the inorganic filler, there is a method of adding a sedimentation preventing agent. Examples of the antisettling agent include polyetherester antisettling agents described in Patent Document 2, fumed silica, acrylic rubber, and the like.

  In addition, carbon black, which has a proven track record of black coloring, was used for the coil insulation process. However, since high voltages are applied to ignition coils for automobiles, conductive carbon black is colored black. It is not possible. Therefore, use of a dye has been studied (for example, see Patent Document 3). In an ignition coil used at a high output, it is necessary to use a dye which does not fade even if it is left for a long time under a high-temperature condition because the operating environment temperature rises. Dyes that do not have fading even after being left for a long time at a high temperature are dyes having a functional group such as a hydroxy group or an amino group.

JP-A-10-60084 JP 2018-12745 A JP-A-2002-121359

  None of the epoxy resin compositions containing the above-described anti-settling agent or the like satisfied the impregnation and insulation properties. In addition, the dyes having a functional group such as the above-mentioned hydroxy group and amino group have insufficient dispersibility.

  The present invention has been made in view of such circumstances, has good impregnation into coils, and has excellent insulating properties sufficiently applicable to ignition coil applications, inorganic fillers and coloring. It is an object of the present invention to provide an epoxy resin composition for casting, which has excellent dispersibility of an agent and can sufficiently prevent fading under standing at high temperatures, and an ignition coil having high reliability.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, set the amount of water adhering to the metal hydroxide to 0.1 to 0.5% by mass, and set the metal hydroxide and a specific functional By combining with a coloring agent having a group, even if a large amount of inorganic filler is blended, it does not settle, ensuring high impregnation into the coil, high dielectric breakdown strength, good dispersibility, and The present inventors have found that an epoxy resin composition for casting which can sufficiently prevent the discoloration of the present invention can be obtained, and have completed the present invention.
The present invention has been completed based on such findings.

That is, the present invention provides the following [1] to [7].
[1] (A) Epoxy resin, (B) acid anhydride, (C) metal hydroxide, (D) inorganic filler (however, excluding (C) metal hydroxide), (E) curing acceleration An agent, and (F) a colorant,
(C) the amount of water adhering to the metal hydroxide is 0.1 to 0.5% by mass, and the (F) colorant is an amino group, an alkylamino group, an imino group, an azo group, a nitro group, or a cyano group. An epoxy resin composition for casting having at least one functional group selected from the group consisting of amide groups, amide groups, alkoxy groups, thiol groups, and hydroxy groups.
[2] The epoxy resin composition for casting according to the above [1], wherein the metal hydroxide (C) is aluminum hydroxide.
[3] The epoxy resin composition for casting according to the above [1] or [2], wherein the (C) metal hydroxide has an average particle size of 0.1 to 5 μm.
[4] The note according to any one of [1] to [3], wherein the (F) colorant is at least one selected from anthraquinone dyes, methine dyes, and azomethine dyes. Epoxy resin composition for molding.
[5] The epoxy resin composition for casting according to any one of [1] to [4], wherein the viscosity at 25 ° C is 20 to 100 dPa · s.
[6] The epoxy resin composition for casting according to any one of the above [1] to [5], which is a casting resin for an in-vehicle ignition coil.
[7] An ignition coil insulated with a cured product of the epoxy resin composition for casting according to any one of [1] to [6].

  According to the present invention, the impregnation property of the coil is good, and it has an excellent insulating property sufficiently applicable to an ignition coil application, and has excellent dispersibility of an inorganic filler and a coloring agent, and is left under high temperature storage. An epoxy resin composition for casting capable of sufficiently preventing fading, and an ignition coil having high reliability can be provided.

Hereinafter, an embodiment for carrying out the present disclosure will be described.
[Epoxy resin composition for casting]
The epoxy resin composition for casting of the present disclosure (hereinafter, also simply referred to as an epoxy resin composition) includes (A) an epoxy resin, (B) an acid anhydride, (C) a metal hydroxide, and (D) an inorganic filler. (Provided that (C) excluding the metal hydroxide), (E) a curing accelerator, and (F) a colorant,
(C) the amount of water adhering to the metal hydroxide is 0.1 to 0.5% by mass, and the (F) colorant is an amino group, an alkylamino group, an imino group, an azo group, a nitro group, or a cyano group. Amide group, alkoxy group, thiol group, and hydroxy group.

  The epoxy resin of the component (A) used in the present disclosure is not particularly limited in molecular structure, molecular weight, etc., as long as it has two or more epoxy groups in one molecule, and is generally used. Can be used. Examples thereof include aromatic epoxy resins such as bisphenol type, novolak type and biphenyl type, glycidyl ether type of polycarboxylic acid, and alicyclic epoxy resin obtained by epoxidation of cyclohexane derivative. These can be used alone or in combination of two or more.

The epoxy equivalent of the epoxy resin (A) is preferably in the range of 150 to 230, more preferably 160 to 200, from the viewpoint of curability.
The epoxy resin (A) is preferably liquid at room temperature (25 ° C.).

  Further, in addition to these, a liquid monoepoxy resin or the like can be used as a combined component, if necessary, for adjusting the viscosity of the epoxy resin composition. When flame retardancy is to be imparted, an epoxy resin modified with a halogen compound, a phosphorus compound, or the like can be used.

  The content of the component (A) in the epoxy resin composition is preferably from 10 to 40% by mass, more preferably from 15 to 35% by mass, and still more preferably from the viewpoint that good curability and cured product properties can be obtained. 20 to 30% by mass. By setting the content to 10% by mass or more, an increase in viscosity can be suppressed, and a decrease in workability can be prevented. By setting the content to 40% by mass or less, a decrease in mechanical strength of the cured product can be prevented.

  The acid anhydride of the component (B) used in the present disclosure can be used without any particular limitation as long as it has an acid anhydride group in a molecule used as a curing agent for an epoxy resin. Alicyclic acid anhydrides such as hydrophthalic anhydride (Me-HHPA), methyltetrahydrophthalic anhydride (Me-THPA) and tetrahydrophthalic anhydride (THPA), aromatic acid anhydrides such as phthalic anhydride, and aliphatics Aliphatic acid anhydrides such as dibasic acid anhydride (PAPA); Above all, an alicyclic acid anhydride can be preferably used.

  The content of the acid anhydride of the component (B) in the epoxy resin composition is preferably 6 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 15 to 30% by mass. By setting the content to 6% by mass or more, the curing of the resin proceeds sufficiently, and by setting the content to 40% by mass or less, a decrease in heat resistance can be suppressed.

  The content of the acid anhydride of the component (B) is determined by the number of epoxy groups (a) in the epoxy resin of the component (A) and the number of acid anhydride groups (b) in the acid anhydride of the component (B). The ratio is adjusted so that the ratio [(a) / (b)] is preferably 0.5 to 1.5, and more preferably 0.8 to 1.2. When the ratio [(a) / (b)] is 0.5 or more, the moisture resistance reliability of the cured product is improved, and when the ratio is 1.5 or less, a decrease in strength of the cured product can be prevented.

The metal hydroxide of the component (C) used in the present disclosure is used as an antisettling agent. The amount of water adhering to the metal hydroxide as the component (C) is 0.1 to 0.5% by mass. When the amount of adhering water is less than 0.1% by mass, the adhering water of the metal hydroxide of the component (C), the epoxy resin of the component (A), the inorganic filler of the component (D) described later, and the component (F) The components may not easily interact with the colorant, and the dispersibility in the epoxy resin composition may be reduced. Further, the viscosity of the epoxy resin composition may be reduced, and the inorganic filler as the component (D) may be liable to settle. On the other hand, when the amount of attached water exceeds 0.5% by mass, the metal hydroxide itself of the component (C) may aggregate and the dispersibility may be reduced. From such a viewpoint, the amount of water adhering to the metal hydroxide as the component (C) is preferably from 0.15 to 0.35% by mass, and more preferably from 0.2 to 0.4% by mass.
The amount of water adhering to the metal hydroxide of the component (C) can be measured according to JIS K 0067 (1992), and specifically, can be measured by the method described in Examples.
The amount of water adhering to the metal hydroxide of the component (C) can be adjusted to the above range by heating or drying or absorbing the metal hydroxide of the component (C).

  The metal hydroxide of the component (C) is not particularly limited as long as the amount of attached water is within the above range, and examples thereof include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, manganese hydroxide, and zinc hydroxide. Can be used. Among them, aluminum hydroxide is preferred from the viewpoint of versatility and manufacturability.

Further, from the viewpoint of dispersibility in the epoxy resin composition, the average particle diameter of the metal hydroxide as the component (C) is preferably from 0.1 to 5 μm, more preferably from 0.5 to 2.5 μm. When the average particle diameter is 0.1 μm or more, a suitable thixotropic property can be provided, and when the average particle diameter is 5 μm or less, an effect of reducing the sedimentation velocity due to the particle diameter of the metal hydroxide (C) itself can be obtained.
The average particle diameter in the present disclosure is a particle diameter (volume average particle diameter d50) represented by a value of 50% by mass on a volume addition curve obtained by a laser method particle measuring device in accordance with JIS Z8825 (2013). It is.

  The content of the metal hydroxide as the component (C) in the epoxy resin composition is preferably 2 to 20% by mass, more preferably 4 to 16% by mass, and still more preferably 6 to 10% by mass. By setting the content to 2% by mass or more, the sedimentation of the inorganic filler of the component (D) described below can be suppressed, and by setting the content to 20% by mass or less, the low viscosity is maintained and the impregnation property is improved. Can be secured.

The inorganic filler of the component (D) used in the present disclosure (excluding the metal hydroxide of the component (C)) is not particularly limited as long as it is an inorganic filler generally used in an ignition coil for an automobile. be able to. For example, silica, alumina, magnesia, boron nitride, aluminum nitride, silicon nitride, talc, calcium carbonate, titanium white, aluminum hydroxide, and the like can be used. Among them, silica is preferable, and as the silica, crushed fused silica, spherical fused silica, crystalline silica, and the like can be used.
These can be used alone or in combination of two or more.

  Commercially available products can be used as the silica. As crushed fused silica, Hughes Rex RD-8 (trade name, average particle size: 18 μm, manufactured by Tatsumori), Hughes Rex WX (trade name, average particle size: 1 μm), etc. Is mentioned. Examples of the spherical fused silica include FB-5D (manufactured by Denka Corporation, trade name, average particle diameter: 6 μm), FB-959 (manufactured by Denka Corporation, trade name, average particle diameter: 18 μm), and MSR15 (manufactured by Denka Corporation) ) Tatsumori, trade name, average particle size: 15 μm), MSR25 (Tatsumori Corporation, trade name, average particle size: 25 μm) and the like. As crystalline silica, Crystallite 5X (trade name, average particle size: 1.5 μm, manufactured by Tatsumori), Crystallite A-A (trade name, average particle size: 6 μm, manufactured by Tatsumori) And Crystallite C (trade name, average particle size: 20 μm, manufactured by Tatsumori Co., Ltd.), and Crystallite CMC-12 (trade name, average particle size: 6.1 μm, manufactured by Tatsumori Co., Ltd.). .

The average particle diameter of the inorganic filler as the component (D) is preferably from 0.5 to 40 μm, more preferably from 1 to 30 μm, from the viewpoint of fluidity and workability.
In addition, the said average particle diameter is a particle diameter (volume average particle diameter d50) shown by 50 mass% value on a volume addition curve calculated | required by the laser method particle measuring device by the method based on JISZ8825 (2013). .

  The content of the inorganic filler as the component (D) in the epoxy resin composition is preferably 30 to 70% by mass, more preferably 35 to 60% by mass, and still more preferably 40 to 50% by mass. When the content of the inorganic filler as the component (D) is 30% by mass or more, the insulation reliability of the epoxy resin composition becomes good. When the content becomes 70% by mass or less, the impregnation property of the epoxy resin composition becomes good. .

As the curing accelerator of the component (E) used in the present disclosure, a curing accelerator generally used for curing an epoxy resin can be used. As the curing accelerator of the component (E), for example, N, N-dimethylbenzylamine, 2,4,6-tris (dimethylaminomethyl) phenol, 2-ethyl-4-methylimidazole (2E4MZ), quaternary Ammonium salts and the like. Among them, it is preferable to use N, N-dimethylbenzylamine and 2-ethyl-4-methylimidazole (2E4MZ) from the viewpoint of curability.
As N, N-dimethylbenzylamine, commercially available products can be used. 20 (manufactured by Kao Corporation, trade name), Curesol 2E4MZ (manufactured by Shikoku Chemical Industry Co., Ltd., trade name), and the like. These can be used alone or in combination of two or more.

  The content of the curing accelerator of the component (E) is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, based on 100 parts by mass of the acid anhydride of the component (B). . By setting the content of the curing accelerator of the component (E) to 0.3 parts by mass or more, the curability of the epoxy resin composition becomes better, and by setting the content to 5 parts by mass or less, Pot life can be extended.

The colorant of the component (F) used in the present disclosure is selected from the group consisting of an amino group, an alkylamino group, an imino group, an azo group, a nitro group, a cyano group, an amide group, an alkoxy group, a thiol group, and a hydroxy group. It has at least one functional group.
Examples of the alkylamino group include those having 1 to 4 carbon atoms such as a methylamino group, an ethylamino group, an n-propylamino group, an isopropylamino group, an n-butylamino group, a sec-butylamino group, and a tert-butylamino group. A linear or branched alkyl having 1 to 4 carbon atoms such as an amino group, a dimethylamino group, a methylethylamino group, a diethylamino group, a dibutylamino group, etc., in which a linear or branched alkyl group is mono-substituted Examples include an amino group in which the group is disubstituted.
Examples of the alkoxy group include a straight or branched chain having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group and a tert-butoxy group. Alkoxy group.
When the colorant of the component (F) has the above-described functional group, the functional group forms a hydrogen bond with the attached moisture of the metal hydroxide of the above-described component (C), thereby improving dispersibility. . Further, the viscosity of the epoxy resin composition further increases, and the viscosity can be set to a range in which the sedimentation of the inorganic filler as the component (D) can be suppressed. From such a viewpoint, the functional group of the colorant of the component (F) is preferably an amino group, an alkylamino group, a nitro group, an amide group, a thiol group, or a hydroxy group, and is preferably an amino group, an alkylamino group, or a hydroxy group. Is more preferred.

  Further, by using the colorant as the component (F), it is possible to suppress the fading property of the epoxy resin composition when left at high temperature.

The colorant of the component (F) is not particularly limited as long as it has the above functional group, and examples thereof include anthraquinone dyes, methine dyes, azo dyes, azomethine dyes, phthalocyanine dyes, quinone imine dyes, and quinoline dyes. Organic dyes such as dyes and nitro dyes; organic pigments such as azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, phthalocyanine pigments, and quinacridone pigments. Among them, from the viewpoint of dispersibility and fading, at least one selected from anthraquinone dyes, methine dyes and azomethine dyes is preferred.
As the colorant of the component (F), commercially available products can be used, for example, Chromofine Black A1103 (trade name, manufactured by Dainichi Seika Kogyo Co., Ltd.), or Kayaset Black as a commercial product already mixed G (manufactured by Nippon Kayaku Co., Ltd., trade name), Sumiplast Black HB (manufactured by Sumika Chemtex Co., Ltd., trade name) and the like.
These can be used alone or in combination of two or more.
The color of the colorant of the component (F) is not particularly limited, but is preferably black.

  The content of the colorant (F) in the epoxy resin composition is preferably 0.05 to 1% by mass, and more preferably 0.1 to 0.5% by mass. When the content is in the range of 0.05 to 1% by mass, color development sufficient for blindfolding can be obtained.

  Furthermore, the epoxy resin composition of the present disclosure preferably contains a coupling agent. By containing the coupling agent, the surface modification of the inorganic filler (D) is performed, and the insulation reliability of the epoxy resin composition is further improved.

  Examples of the coupling agent include a silane coupling agent, a titanium-based coupling agent, and an aluminum-based coupling agent. From the viewpoint of improving moisture resistance and strength, a silane coupling agent is preferable, and an epoxy silane coupling agent is particularly preferable.

  Examples of the epoxy silane coupling agent include γ-glycidoxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE-402), and γ-glycidoxypropyltrimethoxysilane (NUC Corporation) (Trade name: A-187), β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (trade name: A-186, manufactured by NUC). These can be used alone or in combination of two or more.

  When a coupling agent is used, the content thereof is preferably 0.01 to 3% by mass, more preferably 0.05 to 1% by mass in the epoxy resin composition. When the content of the coupling agent is 0.01 to 3% by mass, the surface modification of the inorganic filler as the component (D) is more effectively performed.

  In the epoxy resin composition of the present disclosure, in addition to the above components, if necessary and to the extent not inconsistent with the spirit of the present invention, it may contain components generally contained in this type of epoxy resin composition. it can. Examples of such components include an antifoaming agent, an antioxidant, and a coloring agent other than the component (F).

  The total content of the components (A) to (F) contained in the epoxy resin composition of the present disclosure is preferably from 80 to 100% by mass, more preferably from 85 to 100% by mass, and still more preferably from 90 to 100% by mass. % By mass.

  The epoxy resin composition of the present disclosure includes (A) an epoxy resin, (B) an acid anhydride, (C) a metal hydroxide, and (D) an inorganic filler (however, excluding the (C) metal hydroxide). , (E) a curing accelerator, and (F) a colorant, and optionally contained optional components.

  Here, the epoxy resin composition of the present disclosure can be a two-part epoxy resin composition including a main agent and a curing agent. When a two-part epoxy resin composition is used, the base agent and the curing agent are mixed at the time of use.

  Examples of the two-part epoxy resin composition include (A) an epoxy resin, (C) a metal hydroxide, (D) an inorganic filler (however, excluding the (C) metal hydroxide), and ( And F) a main agent containing a coloring agent, and (B) a curing agent containing an acid anhydride and (E) a curing accelerator.

The viscosity at 25 ° C. of the epoxy resin composition of the present disclosure is preferably 20 to 100 dPa · s, and more preferably 30 to 95 dPa · s. The viscosity of the main agent at 70 ° C. is preferably from 200 to 1,000 dPa · s, and more preferably from 300 to 900 dPa · s.
In addition, the viscosity of the epoxy resin composition and the viscosity of the main agent are values measured using a B-type viscometer at a rotation speed of 1.5 rpm.

  The epoxy resin composition of the present disclosure has good impregnation into coils, and has excellent insulating properties and dispersibility sufficiently applicable to ignition coil applications, and sufficiently prevents discoloration under high temperature storage. Therefore, it can be suitably used as a cast resin for an in-vehicle ignition coil.

  The epoxy resin composition of the present disclosure is suitably used, for example, for impregnating and curing a coil around which a coated copper wire is wound, to produce a molded coil. As the impregnation method, a method by casting is preferred. As a curing method, a method by heating is preferable.

  Examples of the molded coil include, but are not particularly limited to, transformers such as a high-voltage transformer. Specifically, there is an ignition coil which is an ignition coil for an automobile. The ignition coil is obtained by impregnating and curing an epoxy resin composition in a coil body in which a primary coil and a secondary coil are provided on a magnetic core.

[ignition coil]
The ignition coil of the present disclosure is insulated by a cured product of the above-described epoxy resin composition for casting.
By using the epoxy resin composition of the present disclosure for manufacturing an ignition coil, the characteristics of the epoxy resin composition are exhibited, and an ignition coil having high insulation reliability can be easily obtained. Usually, the volume occupied by the epoxy resin composition in the ignition coil is preferably 30% by volume or less.

  Examples of the ignition coil include a pen-type ignition coil in which a coil body impregnated and cured with an epoxy resin composition is accommodated in a cylindrical plastic case. The coil body used in such a pen-type ignition coil includes, for example, a magnetic core, an outer core, a primary bobbin, a primary coil, a secondary bobbin, a secondary coil, a case, and terminals. One in which a coated conductive wire of 50 μm or less is wound. The plastic case is, for example, one having a diameter of 2.0 cm or less.

  Examples of the ignition coil include a rectangular ignition coil in which a coil body impregnated and cured with an epoxy resin composition is housed in a box-shaped plastic case. As a coil body used for such a rectangular ignition coil, for example, a coil body in which a coated conductor having a diameter of 30 μm or less or 50 μm or less is wound around a magnetic core can be mentioned. In addition, as the plastic case, for example, a plastic case having a size of about 4.0 cm square can be used.

  Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Preparation Example 1: (C) Preparation of amount of water adhering to metal hydroxide)
As the metal hydroxide of the component (C), 300 g of aluminum hydroxide (trade name: H42M, manufactured by Showa Denko, average particle size: 1.5 μm) was collected, and the water content was 0.2% by mass at 120 ° C. The resultant was dried by heating until it became as it was to obtain aluminum hydroxide (c-1) [adhered water content: 0.2% by mass]. Aluminum hydroxide (c-3) [adhered water content: 0.05% by mass] was obtained in the same manner as above except that the heating and drying time was changed.
In addition, 300 g of aluminum hydroxide (manufactured by Showa Denko, trade name: H42M, average particle size: 1.5 μm) was sampled and allowed to absorb moisture at a temperature of 40 ° C. and 90% atmosphere until the water content became 0.2% by mass. Aluminum hydroxide (c-2) [moisture content: 0.4% by mass] was obtained. Aluminum hydroxide (c-4) [adhered water content: 0.6% by mass] was obtained in the same manner as above except that the moisture absorption time was changed.
The water content of the obtained aluminum hydroxides (c-1) to (c-4) was measured and confirmed at a temperature of 150 ° C. in accordance with JIS K 0067 (1992).

(Example 1)
As described below, a two-part epoxy resin composition comprising a main agent and a curing agent was produced, and the main agent and the curing agent were mixed at the time of use.

  The main component is 25.5 parts by mass of a bisphenol A type epoxy resin (trade name: jER (registered trademark) 828, epoxy equivalent: 184 to 194, manufactured by Mitsubishi Chemical Corporation) as the epoxy resin of the component (A), (C 8) parts by mass of the aluminum hydroxide (c-1) prepared in Preparation Example 1 (adhered water amount: 0.2% by mass, average particle size: 1.5 μm) as the metal hydroxide of the component (D) 45 parts by mass of silica (trade name: Crystallite CMC-12, average particle size: 6.1 μm) as an inorganic filler of 45 parts by mass, and a coloring agent (f-1) as a coloring agent of the component (F) ) [Mixture of anthraquinone dye and methine dye] [manufactured by Nippon Kayaku Co., Ltd., trade name: Kayaset Black G] 0.1 parts by mass, silane coupling agent [manufactured by NUC, trade name: A -187] 0.15 parts by mass, defoaming [Momentive Performance Materials Co., Ltd., trade name: TSA720] 0.05 part by weight, were charged into a universal mixer heated to 120 ° C., was prepared 2 hours, then mixed under vacuum.

  The curing agent is 21 parts by mass of tetrahydrophthalic anhydride (trade name: HN2200, manufactured by Hitachi Chemical Co., Ltd.) as an acid anhydride of component (B), and N, N-dimethylbenzylamine as a curing accelerator of component (E) [Kao Co., Ltd., trade name: Kao Riser No. 20] 0.2 parts by mass were charged into a universal mixer heated to 60 ° C., and mixed at normal pressure for 0.5 hour to produce.

  27 parts by mass of the curing agent were mixed with 100 parts by mass of the main agent using a universal mixer to produce an epoxy resin composition for evaluation.

(Examples 2 to 7, and Comparative Examples 1 to 5)
An epoxy resin composition for evaluation was obtained in the same manner as in Example 1 by blending each part by mass of the components shown in Tables 1 and 2.

The details of the components other than those used in the production of the epoxy resin compositions for evaluation in Examples 2 to 7 and Comparative Examples 1 to 5 are shown below.
(Main agent)
<Epoxy resin composition>
[(A) component]
JER (registered trademark) 807: bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name, epoxy equivalent: 160 to 175

<Metal hydroxide>
[(C) component]
-Aluminum hydroxide (c-2): aluminum hydroxide prepared in Preparation Example 1, amount of attached water: 0.4% by mass, average particle diameter: 1.5 µm

[Metal hydroxide not satisfying the attached water content of 0.1 to 0.5% by mass]
-Aluminum hydroxide (c-3): aluminum hydroxide prepared in Preparation Example 1, amount of attached water: 0.05% by mass, average particle diameter: 1.5 µm
-Aluminum hydroxide (c-4): aluminum hydroxide prepared in Preparation Example 1, water content: 0.6% by mass, average particle size: 1.5 µm

<Anti-settling agent other than component (C)>
Aerosil (registered trademark) # 200: manufactured by Nippon Aerosil Co., Ltd., trade name, average particle diameter: 12 nm

<Colorant>
[(F) component]
Colorant (f-2) [azomethine dye]: manufactured by Dainichi Seika Kogyo Co., Ltd., trade name: Chromofine Black A1103

<Coloring agent other than component (F)>
-Pigment Red 224 (3,4,9,10-perylenetetracarboxylic dianhydride): trade name, manufactured by Tokyo Chemical Industry Co., Ltd.- MA600 (carbon black): trade name, manufactured by Mitsubishi Chemical Corporation.

  Next, the following evaluation was performed about the epoxy resin composition for evaluation of an Example and a comparative example. The results are shown in Tables 1 and 2.

<Evaluation items>
(Evaluation of epoxy resin composition)
(1) Viscosity The viscosity of the main agent was measured using a B-type viscometer at a temperature of 70 ° C. and a rotation speed of 1.5 rpm. The viscosity of the epoxy resin composition obtained by mixing the main agent and the curing agent was measured using a B-type viscometer at a temperature of 25 ° C. and a rotation speed of 1.5 rpm.

(2) Dispersibility of Main Agent Component The main agent was placed on a glass plate in an amount of 0.2 g, the upper portion was sandwiched between preparations, and observed with a microscope (100 times magnification). This was observed at the initial stage and at regular intervals, and the change in dispersion up to 1000 hours was observed and evaluated according to the following criteria.
[Evaluation criteria for dispersibility]
：: no aggregation after 1000 hours or more ×: aggregation after less than 1000 hours

(3) Sedimentation property of the main component 1 kg of the main component was poured into a 1 L round can (110 mm in diameter) and left at 100 ° C for 24 hours. After the standing, the layer thickness of the inorganic filler settled on the bottom of the round can was measured as the height from the bottom using a stainless steel ruler, and evaluated according to the following criteria.
[Evaluation criteria for sedimentation]
：: No deposit ○: Deposit thickness less than 1 mm ×: Deposit thickness 1 mm or more

(4) Gel time A test tube into which 10 g of the epoxy resin composition was injected was placed in an oil bath at 140 ° C., and the time required for the epoxy resin composition to cure was measured.

(Evaluation of cured product)
(1) Glass transition point A cured product obtained by heating and curing the epoxy resin composition at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours was subjected to a TMA method at a temperature increasing rate of 15 ° C./min and room temperature (25 ° C.). ) To 185 ° C. for measurement.

(2) Flexural strength and flexural modulus A cured product obtained by heating and curing the epoxy resin composition at 100 ° C for 3 hours and then at 140 ° C for 3 hours at a temperature of 25 ° C according to JIS C2105 (2006). It was measured.

(3) Dielectric breakdown strength The cured product obtained by heating and curing the epoxy resin composition at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours is cured using a dielectric breakdown tester manufactured by Tokyo Seiden Co., Ltd. The dielectric breakdown voltage of the product was measured at a temperature of 25 ° C. according to JIS C2110-1 (2010).

(4) Volume resistivity A cured product obtained by heating and curing the epoxy resin composition at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours is applied with DC 500 V according to JIS C2110-1 (2010). At a temperature of 25 ° C. and 100 ° C. For the measurement, a 4329A high resistance meter (product name) manufactured by Yokogawa Hewlett-Packard Co., Ltd. was used.

(5) Relative dielectric constant, dielectric loss tangent The cured product obtained by heating and curing the epoxy resin composition at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours was tested for the dielectric constant of the electric insulation material manufactured by Soken Electric Co., Ltd. Using a dielectric loss tangent measuring device, the measurement was performed at a temperature of 25 ° C. and 100 ° C. under a 50 Hz condition according to JIS C2138 (2007).

[Evaluation of coil]
(1) Impregnability After heating the main agent at 100 ° C. for 1 hour and the curing agent at 40 ° C. for 1 hour, mix the main agent and the curing agent and stir at 60 ° C. for 10 minutes to test the epoxy resin composition obtained. A coil (winding diameter: 40 μm, number of turns: 22000) was impregnated by vacuum injection, and the epoxy resin composition was cured by heating at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours. Thereafter, the test coil impregnated and cured with the epoxy resin composition for evaluation is cut, the cross section is observed, and the area of the impregnated portion impregnated with the epoxy resin composition is impregnated with the epoxy resin composition. The area of the unimpregnated portion that was not impregnated was determined. And the impregnation rate was calculated | required by the following formula, and it evaluated by the following reference | standard.
Impregnation rate (%) = (area of impregnated part / (area of impregnated part + area of unimpregnated part)) × 100
[Evaluation criteria for impregnation]
：: Impregnation rate is 99% or more ：: Impregnation rate is 95% or more and less than 99% ×: Impregnation rate is less than 95%

(2) Crack resistance (reliability)
As a test coil, a bobbin (manufactured by SABIC, trade name: IGN5531, diameter: 11 mm, material: PPE) provided with a coil (diameter: 40 μm, number of turns: 22000, material: enameled wire) is a pen type case ( DIC Corporation, trade name: FZ2140, length 40 mm, width 30 mm, depth 30 mm, thickness 1 mm, material: PPS) were prepared. The test coil was impregnated with the epoxy resin composition for evaluation by vacuum injection, and the epoxy resin composition was cured by heating at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours. Thereafter, after holding at -30 ° C for 1 hour, holding at 140 ° C for 1 hour, a cooling / heating cycle was performed with one cycle as a cycle, and the number of cycles until cracks occurred in the portion made of the epoxy resin composition for evaluation Was measured and evaluated according to the following criteria.
[Evaluation criteria for crack resistance (reliability)]
◎: The number of cycles until cracks occurred was 150 or more ：: The number of cycles until cracks occurred was 100 or more and less than 150 ×: The number of cycles until cracks occurred was less than 100

(3) Fading property The cured product obtained by heating and curing the epoxy resin composition at 100 ° C. for 3 hours and then at 140 ° C. for 3 hours was measured using a colorimeter (CR-300, manufactured by Konica Minolta, Inc.). According to JIS Z8781-4 (2013), L ₀ *, a ₀ *, and b ₀ * were measured (measurement frequency N = 3), and the respective average values were calculated. Further, the cured product was left under 0.99 ° C., _L after 1000 hours n _{*, a} n *, and _{b n} * measured (number of measurements N = 3), respectively to calculate the average value. Using the respective average _{values, L 0 *, a 0 *} , a _{b 0 *, L n *,} a n *, b n * difference, respectively between ΔL *, Δa *, and the [Delta] b *, the following formula The color difference (ΔE) was determined.
ΔE = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2
[Evaluation criteria for fading]
：: ΔE is less than 5 at 1000 hours ×: ΔE is 5 or more at 1000 hours

  The epoxy resin compositions of the examples containing the components (A) to (F) have good impregnation into the coil, have excellent insulation and dispersibility, and sufficiently prevent discoloration under high temperature storage. Thus, an ignition coil having excellent reliability can be obtained.

Claims (7)

(A) an epoxy resin, (B) an acid anhydride, (C) a metal hydroxide, (D) an inorganic filler (however, excluding the (C) metal hydroxide), (E) a curing accelerator, and (F) a coloring agent,
(C) the amount of water adhering to the metal hydroxide is 0.1 to 0.5% by mass, and the (F) colorant is an amino group, an alkylamino group, an imino group, an azo group, a nitro group, or a cyano group. An epoxy resin composition for casting having at least one functional group selected from the group consisting of amide groups, amide groups, alkoxy groups, thiol groups, and hydroxy groups.   The epoxy resin composition for casting according to claim 1, wherein the metal hydroxide (C) is aluminum hydroxide.   3. The casting epoxy resin composition according to claim 1, wherein the metal hydroxide has an average particle diameter of 0.1 to 5 [mu] m.   The epoxy resin for casting according to any one of claims 1 to 3, wherein the colorant (F) is at least one selected from an anthraquinone dye, a methine dye, and an azomethine dye. Composition.   The epoxy resin composition for casting according to any one of claims 1 to 4, wherein the viscosity at 25 ° C is 20 to 100 dPa · s.   The epoxy resin composition for casting according to any one of claims 1 to 5, which is a casting resin for an in-vehicle ignition coil.   An ignition coil insulated by a cured product of the epoxy resin composition for casting according to any one of claims 1 to 6.