JP2009203431A - Epoxy resin composition for casting and highly heat conductive coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for casting, improving workability without causing negatively affect on mechanical properties of devices such as a casted ignition coil, suppressing sedimentation of fillers, and excellent in electrical properties. <P>SOLUTION: The epoxy resin composition for casting comprises, as essential ingredients, a principal ingredient comprising (A) an epoxy resin, (B1) crushed fused silica of 10-20 μm number-average particle diameter and (B2) spherical fused silica of 10-30 μm number-average particle diameter, and a curing agent ingredient comprising (C) an alicyclic acid anhydride curing agent, (D1) crushed fused silica of 10-20 μm number-average particle diameter, (D2) spherical fused silica of 10-30 μm number-average particle diameter and (E) a sedimentation preventive comprising organic bentonite. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an epoxy resin composition that is cast-impregnated with electrical and electronic parts such as coils, and more particularly to an epoxy resin composition for casting suitable for use as an insulating material for automobile ignition coils and industrial modules. The present invention relates to a high thermal conductive coil obtained using

  Conventionally, a coil or the like incorporated in an electric / electronic device has been cast impregnated with an epoxy resin composition in order to protect it from an external atmosphere or mechanical shock. This casting epoxy resin composition is based on an epoxy resin, and it contains a curing agent, a curing accelerator, and an inorganic filler such as silica powder. It is used for the insulation process of the module for a process (for example, refer patent document 1).

  Among transformers for electronic equipment for automobiles, ignition coils are manufactured by an insulation treatment with an epoxy resin composition. However, the resin composition for this application has been required to have particularly strict characteristics. What is excellent in crack property, electrical property, mechanical property and heat resistance is required.

Furthermore, in recent years, workability has become more severe in addition to these characteristics, and similarly, demands for heat resistance and a low expansion coefficient are increasing for industrial modules.
Japanese Patent Laid-Open No. 4-63828

  Conventionally, in an epoxy resin composition for casting in such an application, when improving the low expansion coefficient, silica of a crushed type, a spherical type or the like is generally used as the fused silica. It was necessary to add so that the filling rate into a resin composition might become high.

  However, the use of such a large amount of silica leads to a decrease in workability of the resin composition, and the filler sedimentation has been remarkably deteriorated. At this time, an acrylic rubber may be added for the purpose of preventing sedimentation, but in this case, the defoaming property is newly reduced.

  Therefore, the object of the present invention was made to eliminate the above-mentioned drawbacks, and without adversely affecting the mechanical properties of the cast ignition coil and other devices, it is excellent in workability and defoaming property, and further, filler Is to provide an epoxy resin composition for casting that is excellent in electrical properties.

  As a result of diligent research to achieve the above object, the present inventors have found that the above object can be achieved by using an epoxy resin composition having a specific composition, and the present invention has been completed.

  That is, the casting epoxy resin composition of the present invention comprises (A) an epoxy resin, (B1) crushed fused silica having a number average particle size of 10 to 20 μm, and (B2) spherical melting having a number average particle size of 10 to 30 μm. A main component containing silica, (C) an alicyclic acid anhydride curing agent, (D1) crushed fused silica having a number average particle size of 10 to 20 μm, and (D2) having a number average particle size of 10 to 30 μm. A curing agent component containing spherical fused silica and (E) an anti-settling agent composed of organic bentonite is an essential component.

  Moreover, the high thermal conductive coil of the present invention is formed by casting the casting epoxy resin composition of the present invention.

  According to the epoxy resin composition of the present invention, while maintaining the mechanical properties, heat resistance, low expansion coefficient, and other properties required as a casting resin for electric and electronic parts, the settling of the filler is prevented and workability is improved. Can be improved. Moreover, according to the high thermal conductive coil of the present invention, since the filler is insulated by the resin in a sufficiently dispersed state, it has a stable performance excellent in electrical characteristics and mechanical characteristics.

  Hereinafter, the present invention will be described in detail.

  The casting epoxy resin composition of the present invention essentially comprises two components: a main component composed of components (A) to (B) and a curing agent component composed of components (C) to (E) described below. It is a two-pack type epoxy resin composition.

  The (A) epoxy resin used in the present invention may be a compound having two or more epoxy groups in one molecule, and can be used without particular limitation, such as a liquid epoxy resin and a solid epoxy resin. For example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, diglycidyl ether of polycarboxylic acid, an epoxy resin obtained by epoxidation of a siloxane derivative, and the like may be used alone or in combination of two or more. it can. In addition to these, a liquid monoepoxy resin or the like can be used as necessary.

  Next, as (B) fused silica used in the present invention, (B1) crushed fused silica having a number average particle size of 10 to 20 μm and (B2) spherical fused silica having a number average particle size of 10 to 30 μm are used. These fused silicas are used in combination and mixed. The fused silica used here can be used without particular limitation as long as it can be used as a filler for the casting epoxy resin composition. And by using together specific fused silica in this way, achievement of low expansion coefficient of epoxy resin composition, improvement of workability, prevention of sedimentation, high impregnation of coils and modules, and improvement of mechanical strength are achieved. be able to.

  These fused silicas (B1) and (B2) can be used without particular limitation other than their shape and number average particle diameter, and (B1) is a specific example that can be used as crushed fused silica. As brands, RD-8 (manufactured by Tatsumori Co., Ltd., trade name; number average particle size 18 μm) and the like (B2) as specific brands that can be used as spherical fused silica, FB-959 (Asahi Denka Co., Ltd.) Made by company, product name; number average particle size 18 μm), MSR15 (manufactured by Tatsumori, product name; number average particle size 15 μm), MSR25 (manufactured by Tatsumori, product name; number average particle size 25 μm) Can be mentioned. The blending amount of the (B) fused silica can be used in any desired amount.

  Next, the (C) alicyclic acid anhydride curing agent used in the present invention is not particularly limited as long as it is an alicyclic curing agent having an acid anhydride group in the molecule. Any material that can be used as a curing agent for an epoxy resin for shaping may be used, for example, hexahydrophthalic anhydride (HHPA), tetrahydrophthalic anhydride (THPA), methylhexahydrophthalic anhydride (ME-HHPA), methyltetrahydro Although phthalic anhydride (ME-THPA) etc. are mentioned, methylhexahydrophthalic anhydride (ME-HHPA) or methyltetrahydrophthalic anhydride (ME-THPA) is preferably used since heat resistance becomes preferable. These acid anhydride curing agents can be used alone or in combination of two or more.

  It is preferable that the compounding quantity of this (C) alicyclic acid anhydride hardening | curing agent is the range used as 5.0-15.0 mass% in the epoxy resin composition for casting.

  Next, (D) fused silica used in the present invention includes two types of (D1) crushed fused silica having a number average particle size of 10 to 20 μm and (D2) spherical fused silica having a number average particle size of 10 to 30 μm. These fused silicas are used in combination and mixed. Both the fused silica used here can be used in the same range as the components (B1) and (B2) of the (B) fused silica described above, and by using a specific fused silica in this way, The low expansion coefficient of the epoxy resin composition, the improvement of workability, the prevention of sedimentation, the high impregnation of coils and modules, and the improvement of mechanical strength can be achieved.

  These fused silicas (D1) and (D2) can be used without particular limitation other than their shape and number average particle diameter, and (D1) is a specific example that can be used as crushed fused silica. As a brand, RD-8 (manufactured by Tatsumori Co., Ltd., trade name; number average particle size 18 μm), etc. (D2) As a specific brand that can be used as spherical fused silica, FB-959 (Asahi Denka Co., Ltd.) Made by company, product name; number average particle size 18 μm), MSR15 (manufactured by Tatsumori, product name; number average particle size 15 μm), MSR25 (manufactured by Tatsumori, product name; number average particle size 25 μm) Can be mentioned.

  The blending amounts of the fused silica of (B) and (D) are (B1) crushed fused silica having a number average particle size of 10 to 20 μm, (B2) spherical fused silica having a number average particle size of 10 to 30 μm, (D1 The total blending amount of crushed fused silica having a number average particle size of 10 to 20 μm and (D2) spherical fused silica having a number average particle size of 10 to 30 μm is 70 to 80 mass% in the epoxy resin composition for casting. It is preferable.

  At this time, the total amount of (B1) crushed fused silica having a number average particle size of 10 to 20 μm and (B2) spherical fused silica having a number average particle size of 10 to 30 μm in the main component, and (D1 The total amount of crushed fused silica having a number average particle size of 10 to 20 μm and (D2) spherical fused silica having a number average particle size of 10 to 30 μm is also preferably 70 to 80% by mass, respectively. That is, it is particularly preferable that the blending amount of the fused silica is not changed before and after mixing.

  Further, the ratio of each of the types (B) and (D) of the fused silica, that is, the blending amount of the crushed fused silica having a number average particle diameter of 10 to 20 μm combining (B1) and (D1), and (B2) And the blended amount of spherical fused silica having a number average particle diameter of 10 to 30 μm, which is a combination of (D2) and (D2), is preferably in the range of (B1 + D1) / (B2 + D2) = 10/90 to 90/10.

  Also in this ratio, (B1) / (B2) in the main agent component and (D1) / (D2) in the curing agent component are 10/90 to 90/10, respectively, in the same manner as the total of the above blending amounts. It is preferable that the ratio for each type of fused silica does not change both before and after mixing.

  The (E) antisettling agent used in the present invention is an organic bentonite, and the organic bentonite is composed of a complex obtained by modifying the crystal surface of montmorillonite, which is a clay mineral, with a quaternary ammonium salt. It is. This organic bentonite suspends and swells in an organic solvent system, thickens, and when a shearing force is applied to the dispersion, the flaky crystals are aligned parallel to the flow, so the viscosity decreases, and the dispersion is When in a stationary state, the flaky crystals are associated with each other by hydrogen bonding of the hydroxyl groups present on the end faces, and the flaky crystals form a network so that the viscosity increases. Specific examples include Esven C (trade name, manufactured by Nippon Organic Clay Co., Ltd.), which is finely powdered and has a thickness of 0.5 μm or less when dispersed.

  The amount of the (E) antisettling agent is preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the (C) alicyclic acid anhydride curing agent. At this time, in the epoxy resin composition Is preferably in the range of 0.015 to 0.3% by mass.

  In this curing agent component, it is preferable to use a cationic curing accelerator having an action of promoting the reaction between the epoxy resin and the curing agent. For example, cationic curing accelerators such as quaternary ammonium salts and tertiary amines are used. Examples of the specific compound include a quaternary ammonium salt M2-100 (manufactured by NOF Corporation, trade name).

  Furthermore, an inorganic filler other than the fused silica, a coupling agent, an antifoaming agent, and other components can be appropriately added and blended with the main component or the curing agent component within a range not departing from the object of the present invention. Examples of the inorganic filler that can be used here include crystalline silica, talc, calcium carbonate, and the like. When these inorganic fillers are added, fused silica and other inorganic fillers are added to the epoxy resin composition. It is preferable that the total blended amount does not exceed 85% by mass.

  The casting epoxy resin composition of the present invention is sufficient by adding the components (A) to (E) described above by conventional methods, that is, epoxy resin, fused silica, curing agent, anti-settling agent and other components. Can be mixed and stirred. The epoxy resin composition for casting thus obtained can be used for casting or impregnation of electric / electronic parts, and is particularly suitable for high heat conductive coils such as automobile ignition coils.

  In order to obtain this electric / electronic component, the epoxy resin composition of the present invention may be cast on an electric / electronic component such as a coil according to a conventional method in a two-component epoxy resin and cured. .

  The epoxy resin composition for casting thus obtained contains fused silica as an essential component as an inorganic filler, but crushed fused silica having a number average particle size of 10 to 20 μm and spherical melt having a number average particle size of 10 to 30 μm. By mixing with silica, it achieves low expansion rate, improved workability, prevention of settling, high impregnation into coils and modules, and improved mechanical strength, and alicyclic acid anhydride curing agent, By using a cationic curing accelerator as a curing accelerator, the conventional epoxy resin composition for casting can dramatically improve the heat distortion temperature from around 130 ° C. to around 140 ° C., High heat resistance can be achieved, and it is particularly suitable for casting and impregnation of a high thermal conductive coil. Furthermore, by setting it as such a composition, the heat_generation | fever temperature of hardening can also be suppressed.

  Next, the present invention will be described by way of examples. The present invention is not limited by these examples.

Example 1
Bisphenol A diglycidyl ether # 383 (trade name, manufactured by Dow Chemical Japan Co., Ltd.) 100 parts by mass, antifoaming agent TSA720 (product name, manufactured by Toshiba Silicone Co., Ltd.) 0.1 part by mass, silane coupling agent A-187 (Japan) Unica Co., Ltd., trade name) Spherical fused silica MSR-15 (trade name, manufactured by Tatsumori Co., Ltd.) 0.5 parts by mass, number average particle size 15 μm -8 (manufactured by Tatsumori Co., Ltd., trade name) 50 parts by mass, aluminum hydroxide H-42M (manufactured by Showa Denko KK, trade name; number average particle size 1 μm) 15 parts by mass, cationic curing accelerator M2-100 (Nippon Yushi Co., Ltd., brand name) 0.85 mass part was mixed and it was set as the main ingredient component.

  Next, 100 parts by mass of methylhexahydrophthalic anhydride (ME-HHPA) HN5500 (trade name, manufactured by Hitachi Chemical Co., Ltd.) as an alicyclic acid anhydride curing agent as a curing agent, antifoaming agent TSA720 (Toshiba Silicone Co., Ltd.) Product, product name) 0.1 parts by mass, silane coupling agent A-187 (manufactured by Nippon Unica Co., Ltd., product name) 0.5 parts by mass, cationic curing accelerator M2-100 (manufactured by NOF Corporation, product) Name) Spherical fused silica MSR-15 (trade name), 0.2 mass parts, number average particle size 15 μm 260 μm, crystalline fused silica RD-8 (Ryu Co., Ltd., product name) (Made by Mori, trade name) 120 parts by weight, 1 part by weight of organic bentonite Sven C (manufactured by Nippon Organic Clay Co., Ltd., trade name) as an anti-settling agent was used as a hardener component.

  The main resin component and the curing agent component were sufficiently mixed to produce an epoxy resin composition for casting.

(Examples 2 to 4)
A casting epoxy resin composition having the composition shown in Table 1 was produced in the same manner as in Example 1.

(Comparative Examples 1-4)
In the same manner as in Example 1, casting epoxy resin compositions were produced according to the compositions shown in Table 2.

  Other components used in Examples and Comparative Examples include spherical fused silica MSR-25 (trade name, manufactured by Tatsumori Co., Ltd.) having a number average particle diameter of 25 μm, methyltetrahydrophthalic anhydride (ME-THPA) HN2000 (Trade name, manufactured by Hitachi Chemical Co., Ltd.), core shell rubber (manufactured by Takeda Pharmaceutical Co., Ltd., trade name: Staphyloid AC-3355; acrylic core shell rubber).

(Test example)
The epoxy resin composition for casting produced in Examples 1-2 and Comparative Examples 1-3 was heat-cured. At this time, the viscosity and sedimentation property of the resin composition in each resin composition, the thermal expansion coefficient, the bending strength, and the heat distortion temperature in the cured product were tested, and the results are shown in Table 3 and Table 4. .

The measurement of each test in the test example was performed under the following conditions.
Sedimentability: After standing at 100 ° C. for 5 hours, the presence or absence of filler deposition was examined visually.
Viscosity: Measured using a B-type viscometer at 60 ° C.
Coil impregnation property: A model coil (500 turns of 0.5 mm copper wire) was prepared, dipped in a mixed solution, cured, and the resin filling amount of the cross section of the cured product was visually measured.
Defoaming property: The time until no bubbles were generated when the mixed solution was deaerated at room temperature at 10 torr was measured.
Linear expansion coefficient: Measured by raising the temperature from 25 ° C. to 250 ° C. at 10 ° C./min by the TMA method. A sample obtained by curing the mixed solution at 150 ° C. for 2 hours was used.
Thermal deformation temperature: Measured according to JIS K 7207. A sample obtained by curing the mixed solution at 150 ° C. for 2 hours was used.
Bending strength: measured according to JIS C 2105 (25 ° C.). A sample obtained by curing the mixed solution at 150 ° C. for 2 hours was used.
Withstand voltage: Measured according to JIS K 6911. A sample obtained by curing the mixed solution at 150 ° C. for 2 hours was used.

  From the results of Tables 3 and 4, the present invention is excellent in the sedimentation degree of the filler, and other characteristics can be maintained, and the present invention is particularly excellent in workability of the epoxy resin for casting. It was confirmed to be a composition.

Claims (6)

A main component containing (A) an epoxy resin, (B1) crushed fused silica having a number average particle size of 10 to 20 μm, and (B2) spherical fused silica having a number average particle size of 10 to 30 μm;
(C) an alicyclic acid anhydride curing agent, (D1) crushed fused silica having a number average particle size of 10 to 20 μm, (D1) spherical fused silica having a number average particle size of 10 to 30 μm, and (E) an organic bentonite An anti-settling agent comprising: a curing agent component comprising:
An epoxy resin composition for casting, characterized by comprising as an essential component.   The epoxy resin composition for casting according to claim 1, wherein the (C) alicyclic acid anhydride curing agent is methylhexahydrophthalic anhydride and / or methyltetrahydrophthalic anhydride.   The said (E) organic bentonite is 0.3-2 mass parts with respect to 100 mass parts of alicyclic acid anhydride hardening | curing agents in a hardening | curing agent component, The note of Claim 1 or 2 characterized by the above-mentioned. Epoxy resin composition for form.   (B1) crushed fused silica having a number average particle size of 10 to 20 μm, (B2) spherical fused silica having a number average particle size of 10 to 30 μm, (D1) crushed fused silica having a number average particle size of 10 to 20 μm, and ( D2) The total amount of spherical fused silica having a number average particle size of 10 to 30 μm is 70 to 80% by mass in the casting epoxy resin composition. The epoxy resin composition for casting according to the item.   The blended amount of crushed fused silica having a number average particle size of 10 to 20 μm combining (B1) and (D1), and the spherical fused silica having a number average particle size of 10 to 30 μm combining (B2) and (D2) The compounding amount is in the range of (B1 + D1) / (B2 + D2) = 10/90 to 90/10, the epoxy resin composition for casting according to any one of claims 1 to 4.   A high thermal conductive coil formed by casting the casting epoxy resin composition according to any one of claims 1 to 5.