JP5547621B2 - Coil parts - Google Patents

Description

  The present invention relates to an epoxy resin composition for injection molding and a coil component, and in particular, an epoxy resin composition for injection molding excellent in thermal conductivity and crack resistance optimal for coil sealing, and using the same The present invention relates to a coil component obtained by sealing a coil.

  In recent years, there is an increasing demand for mechanical strength, heat resistance, chemical resistance, and the like for component materials constituting electric / electronic equipment, automobile equipment, chemical equipment, and the like for the purpose of downsizing and weight reduction of equipment. Furthermore, electronic component manufacturing apparatuses and processing apparatuses are becoming smaller and faster, and servo motors that drive them are also becoming smaller.

  As with the above, other motors have been rapidly reduced in size and increased in output, and as a result, the resin that seals coil components has characteristics such as the ability to quickly dissipate the heat generated in the coil section, and operation. Toughness corresponding to the heat cycle accompanying ON / OFF is required. In addition, a resin molded motor is known in which a coil component is hermetically sealed with a synthetic resin to form a housing, and a rotor is built therein via a bearing.

  By the way, epoxy resin has excellent mechanical properties in addition to its good heat resistance and chemical resistance. Furthermore, the combination of epoxy resin curing agent and various additives makes it possible to design blends according to the purpose. Therefore, it is widely used for sealing / molding electric parts such as resin mold motors, and injection-moldable epoxy resins are also widely used.

  For example, an epoxy resin is blended with an inorganic filler made of magnesium oxide or zinc oxide with high thermal conductivity, and further blended with butadiene rubber and glass fiber, has high toughness and thermal conductivity, and good injection An epoxy resin composition having moldability is disclosed (see Patent Document 1).

  In addition, by combining an ortho-cresol novolac type epoxy resin, a novolac phenol resin, a dimethylurea curing accelerator, fused silica, and glass fiber, an epoxy resin composition excellent in fluidity and mechanical properties and capable of injection molding is obtained. It is disclosed (see Patent Documents 2 and 3). Furthermore, a resin composition of a molded product having high mechanical strength by a combination of a polyfunctional epoxy resin, a phenol resin, and a urea curing accelerator is disclosed (see Patent Document 4).

JP-A-8-157663 JP 2001-106791 A JP 2001-278948 A JP 2002-302531 A

  However, when blending magnesium oxide or zinc oxide, the strength of the cured product is inevitably reduced, and it is necessary to blend synthetic rubber and glass fiber. Since the blending amount of the inorganic filler is reduced, there is a possibility that sufficient heat conduction performance may not be obtained, and there is a problem that it is difficult to achieve both high heat conductivity and crack resistance. Further, the orthocresol novolac type epoxy resin or the combination of the polyfunctional type epoxy resin and the novolak phenol resin also has the problem that the fluidity is lowered and it is difficult to achieve both high thermal conductivity and crack resistance.

  The present invention has been made to solve the above-mentioned problems, and has excellent fluidity at the time of molding and has excellent injection moldability. Further, after curing, it is excellent in thermal conductivity and crack resistance. An object of the present invention is to provide an epoxy resin composition and a highly reliable coil component obtained by sealing and forming a coil using the epoxy resin composition.

This onset Ming, a solid epoxy resin containing as a main component (A) a bisphenol A type solid epoxy resin in a range of the average epoxy equivalent is 400 to 490, with respect to the curing agent (B) the total amount of phenol and benzaldehyde And / or a solid phenol resin curing agent containing a polyfunctional phenol resin having a polycondensation unit with hydroxybenzaldehyde in a proportion of 70% by mass or more, and (C) the maximum particle size is 150 μm or less, and the average particle size is 15 to 30 μm of silica, (D) a dimethylurea-based curing accelerator, and (E) an epoxy-based silane coupling agent are essential components, and 75 (C) silica is added to the total amount of the resin composition. coil portion obtained by injection molding epoxy resin composition comprising a proportion of 90% by mass to seal the coils by injection molding To provide.

  According to the present invention, the epoxy resin composition for injection molding having excellent fluidity at the time of molding and excellent in injection moldability and further excellent in thermal conductivity and crack resistance after curing, and a coil using the same. A highly reliable coil component formed by sealing molding can be provided.

  Embodiments of the present invention will be described below. In addition, this invention is limited to the following description and is not interpreted.

<Epoxy resin composition for injection molding>
The epoxy resin composition for injection molding of the present invention contains the following components (A) to (D) as essential components.
(A) Solid epoxy resin (based on bisphenol A type solid epoxy resin having an average epoxy equivalent in the range of 400 to 490)
(B) Solid phenol resin curing agent (contains a polyfunctional phenol resin having a polycondensation unit of phenols and benzaldehydes and / or hydroxybenzaldehydes in a proportion of 70% by mass or more based on the total amount of the curing agent.)
(C) Silica (The content ratio of (C) silica with respect to the total amount of the resin composition is 75 to 90% by mass.)
(D) Dimethylurea curing accelerator In this specification, “solid” such as solid epoxy resin, bisphenol A type solid epoxy resin, solid phenol resin curing agent, etc. means solid at 25 ° C. .

Hereinafter, each component used for the epoxy resin composition for injection molding of this invention is demonstrated.
(A) Solid epoxy resin The bisphenol A type solid epoxy resin which the solid epoxy resin used for this invention contains as a main component has an average epoxy equivalent in the range of 400-490. When the average epoxy equivalent in the bisphenol A type solid epoxy resin is less than 400, the resulting molded article has poor crack resistance. On the other hand, when the average epoxy equivalent of the bisphenol A type solid epoxy resin exceeds 490, the filling property of the obtained molded product is inferior.
The average epoxy equivalent of the bisphenol A type solid epoxy resin is preferably 420 to 480.

Moreover, since the compounding quantity of the silica of (C) component in the epoxy resin composition for injection molding can be enlarged by making the range of the average epoxy equivalent of a bisphenol A type solid epoxy resin into the said range, thermal conductivity Excellent epoxy resin composition for injection molding can be obtained.
The bisphenol A type solid epoxy resin may be composed of one kind or a combination of two or more kinds as long as the average epoxy equivalent as a whole is in the above range and is solid at 25 ° C. Good.

When the bisphenol A type solid epoxy resin is composed of one kind, one having a solid form alone and having an average epoxy equivalent in the range of 400 to 490 is used. When the bisphenol A type solid epoxy resin is composed of two or more combinations, the individual bisphenol A type epoxy resins used for the combination do not necessarily satisfy the above conditions. What is necessary is just to satisfy the said conditions.
As the bisphenol A type epoxy resin used in such a combination, a bisphenol A type solid epoxy resin or a semi-solid bisphenol A type epoxy resin having an epoxy equivalent of 200 to 1000 and a softening point of 60 to 100 ° C. is preferable.

  As the bisphenol A type epoxy resin (solid or semi-solid), for example, the following commercially available products can be used. As commercial products, YD-011 (epoxy equivalent: 475), YD-012 (epoxy equivalent: 650), YD-013 (epoxy equivalent: 850), YD-014 (epoxy equivalent: 950) (above, Tohto Kasei Co., Ltd.) Manufactured, product name), Epicron series 860 (epoxy equivalent: 245), 1050 (epoxy equivalent: 450), 1055 (epoxy equivalent: 450), 2050 (epoxy equivalent: 630), 2055 (epoxy equivalent: 630), 3050 (epoxy equivalent: 780), 3055 (epoxy equivalent: 780), 4050 (epoxy equivalent: 950) (above, manufactured by DIC, product name) and the like.

  As described above, among these, a bisphenol A type solid epoxy resin having an average epoxy equivalent of 400 to 490 can be blended alone in the epoxy resin composition for injection molding of the present invention as the bisphenol A type solid epoxy resin. On the other hand, among these, bisphenol A type epoxy resins (solid or semi-solid) whose average epoxy equivalent is not in the range of 400 to 490 are other bisphenol A so that the average epoxy equivalent is in the range of 400 to 490. Used in combination with type epoxy resin (solid or semi-solid). In addition, in the bisphenol A type solid epoxy resin having an average epoxy equivalent of 400 to 490, it is possible to use two or more of these in combination, and the bisphenol A type having an average epoxy equivalent not in the range of 400 to 490. It is also possible to use in combination with an epoxy resin (solid or semi-solid).

  In addition, in the epoxy resin composition for injection molding of this invention, it is preferable that content of (A) solid epoxy resin is 10-15 mass% with respect to the resin composition whole quantity, and is 10-12 mass%. More preferably. If this content is less than 10% by mass, the fluidity may decrease and unfilling of the molded product may occur. If the content exceeds 15% by mass, the injection pressure will be insufficient due to high fluidization and internal voids will occur. Tend to.

(B) Solid phenol resin curing agent (B) The solid phenol resin curing agent used in the present invention is a polyfunctional phenol having a polycondensation unit of phenol and benzaldehyde and / or hydroxybenzaldehyde with respect to the total amount of the curing agent. Resin (hereinafter referred to as “polyfunctional phenol resin (b)”) is contained in a proportion of 70% by mass or more. (B) The solid phenol resin hardening | curing agent contains the said polyfunctional phenol resin (b) with the said compounding quantity, and the hardened | cured material effective in crack resistance is made.
In the present invention, the content ratio of the polyfunctional phenol resin (b) with respect to the total amount of the curing agent is 70% by mass or more as described above, and more preferably 100% by mass. The polyfunctional phenol resin (b) is not necessarily solid, but is solid when the (B) solid phenol resin curing agent is composed only of the polyfunctional phenol resin (b).

Here, in this specification, the term phenols is used as a general term for a group of phenol-related compounds composed of phenol and phenol substituted with hydrogen bonded to a benzene ring. The same applies to benzaldehydes and hydroxybenzaldehydes.
The polyfunctional phenol resin (b) is not particularly limited as long as it is a polyfunctional phenol resin having a polycondensation unit of such phenols and benzaldehydes and / or hydroxybenzaldehydes.

  Specifically, the polyfunctional phenol resin (b) may have only a polycondensation unit of phenols and benzaldehydes or a polycondensation unit of phenols and hydroxybenzaldehydes, or both. You may have.

  Here, about the hydroxyl equivalent of the said polyfunctional phenol resin (b) used for this invention, it is preferable to exist in the range of 90-105. In this invention, such a polyfunctional phenol resin (b) may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among the polyfunctional phenol resins (b), as the polyfunctional phenol resin having a polycondensation unit of phenols and hydroxybenzaldehydes, specifically, a polyfunctional phenol represented by the following structural formula (1) Resin.

（ただし、式（１）中、Ｒはそれぞれ独立して水素原子または炭素数１〜１０の置換または非置換の１価の炭化水素基を示し、ｎは１〜１０の整数を示す。）

(However, in formula (1), each R independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 1 to 10.)

  Specifically, as the polyfunctional phenol resin represented by the above formula (1), a phenol-hydroxybenzaldehyde resin having a hydroxyl equivalent of 100 and a softening point of 83 ° C. (trade name: MEH, manufactured by Meiwa Kasei Co., Ltd.), wherein R is a hydrogen atom. -7500).

  The (B) solid phenolic resin curing agent used in the present invention is solid when used in combination with the polyfunctional phenolic resin (b) as a phenolic resin curing agent that can be contained in addition to the polyfunctional phenolic resin (b). If it takes the form, it will not specifically limit. Specific examples of such phenol resin curing agents include novolak-type phenol resins obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde, such as phenol novolac resins, cresol novolac resins, and the like. Examples include modified resins such as epoxidized or butylated novolak type phenol resins, dicyclopentadiene modified phenol resins, paraxylene modified phenol resins, and the like. Furthermore, condensates of phenols or naphthols with para-xylene dimethyl ether, for example, phenol aralkyl resins, naphthol aralkyl resins, or the like, or polyfunctional phenol resins other than the above polyfunctional phenol resin (b) may be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Moreover, the compounding quantity of these (B) solid phenol resin hardening | curing agents in the epoxy resin composition for injection molding of this invention is the number of epoxy groups (x) and (B) solid phenol resin hardening which said (A) solid epoxy resin has. The blending amount is preferably such that the ratio (x) / (y) to the number of phenolic hydroxyl groups (y) of the agent is in the range of 0.8 to 1.2. If (x) / (y) is less than 0.8, the moisture resistance reliability of the cured product may be reduced. Conversely, if it exceeds 1.2, the strength of the cured product may be reduced.

(C) Silica In the epoxy resin composition for injection molding of the present invention, (C) silica is blended in a proportion of 75 to 90% by mass with respect to the total amount of the resin composition. When this compounding quantity is less than the lower limit, the thermal conductivity is lowered, the heat dissipating property is insufficient, and the electrical characteristics are deteriorated. When the upper limit is exceeded, the fluidity is lowered and the appearance of the injection molded product becomes poor. In addition, the compounding quantity of (C) silica with respect to the resin composition whole quantity becomes like this. Preferably it is 80-90 mass%.

  Examples of the silica (C) used in the present invention include crystalline silica, fused crushed silica, fused spherical silica, secondary agglomerated silica, and the like. Silica mainly composed of crystalline silica is preferred. (C) As a compounding quantity of the crystalline silica in a silica, it is preferable that it is 75 mass% or more with respect to the whole quantity of (C) silica, and it is more preferable that it is 85 mass% or more. (C) If the blending amount of crystalline silica relative to the total amount of silica is less than 75% by mass, good thermal conductivity may not be obtained.

Furthermore, the shape of the silica (C) is not particularly limited as long as it is a shape that is homogeneously dispersed in the epoxy resin composition to be blended, and specific examples include powder, beads, etc. In the invention, the powder form is preferred.
Regarding the size of the silica powder, for example, in the crystalline silica powder, the maximum particle size is preferably 150 μm or less and the average particle size is preferably 15 to 30 μm. If the maximum particle size exceeds the upper limit value, unfilled defects or defective appearance of the coil parts may occur, and if the average particle diameter is out of the above range, the fluidity may decrease and the appearance of the coil parts may deteriorate. This is not preferable. In addition, the silica powder other than the crystalline silica powder is preferably a powder having the same size as the crystalline silica powder.

  In the epoxy resin composition for injection molding of the present invention, the (C) silica is more preferably a crystalline silica powder having a maximum particle size of 150 μm or less and an average particle size of 15 to 30 μm. Silica blended in a proportion of 75% by mass or more with respect to the total amount of is used.

(D) Dimethylurea-based curing accelerator (D) The dimethylurea-based curing accelerator used in the present invention is not particularly limited as long as it is a dimethylurea-based compound that is usually blended as a curing accelerator in an epoxy resin composition. Used. The dimethylurea curing accelerator usually has an action of promoting the reaction between the epoxy resin and the curing agent at 150 ° C. or higher. Therefore, the epoxy resin curing reaction does not proceed under the cylinder temperature during injection molding, where the normal set temperature is about 90-100 ° C, and the reaction promoting effect is exhibited during curing by heating at 150 ° C or higher after filling the mold. It becomes possible to do. Thereby, the continuous formability of coil components can be improved.

  The blending amount of the (D) dimethylurea curing accelerator in the epoxy resin composition for injection molding of the present invention is the sum of the (A) solid epoxy resin and (B) solid phenol resin curing agent contained in the resin composition. A blending amount of 0.1 to 3.0 parts by weight is preferable with respect to 100 parts by weight, and a blending amount of 0.1 to 2.5 parts by weight is more preferable. If the amount is less than 0.1 parts by mass, the effect of promoting curing is not sufficiently observed. If the amount exceeds 3.0 parts by mass, the reactivity becomes so high that the resin thickens before being completely filled, which is not preferable.

(Epoxy resin composition for injection molding)
The epoxy resin composition for injection molding of the present invention includes the above-described (A) solid epoxy resin (based on a bisphenol A type solid epoxy resin having an average epoxy equivalent in the range of 400 to 490), (B) solid. Phenol resin curing agent (containing a polyfunctional phenol resin having a polycondensation unit of phenols and benzaldehydes and / or hydroxybenzaldehydes in a proportion of 70% by mass or more based on the total amount of the curing agent), (C) Silica (the content ratio of (C) silica relative to the total amount of the resin composition is 75 to 90% by mass) and (D) a dimethylurea-based curing accelerator are essential components, but are not contrary to the object of the present invention. In addition, if necessary, various fillers, mold release agents such as natural waxes and synthetic waxes, antimony trioxide, brominated epoxy Flame retardants such as resins, colorants such as carbon black, low stress imparting agents such as rubber and silicone polymers, coupling agents such as amine-modified and epoxy-modified silicone oils, alumina, titanium white, aluminum hydroxide, talc, etc. These inorganic fillers can be added and blended as appropriate.

  As a method for preparing the injection-molded epoxy resin composition of the present invention as a molding material, a general method can be used. Specifically, a predetermined amount of each of the essential components described above and an appropriate amount of other components that are appropriately selected are blended, and these are mixed sufficiently uniformly with a mixer or the like, and then further melt mixed with a hot roll, or kneader. The mixture can be heated and mixed (heating temperature is generally 70 to 100 ° C.), then cooled and solidified, and pulverized to an appropriate size to obtain a molding material. The molding material thus obtained can be imparted with excellent characteristics and reliability when applied to sealing, coating, insulation, etc. of electronic parts or electrical parts.

<Coil parts>
The coil component of the present invention is a coil component obtained by sealing a coil by injection-molding the epoxy resin composition for injection molding of the present invention obtained above.
As a method for producing a coil component of the present invention, the coil is usually sealed by injection molding using the epoxy resin composition, except that the epoxy resin composition to be used is the epoxy resin composition for injection molding of the present invention. The method can be applied without particular limitation.

  Specifically, the stator core (coil) containing the winding is first inserted into the core of the molding die, and then the upper die is closed. Next, using an injection molding machine, the epoxy resin composition for injection molding is injected from the gate, and the resin composition is further cured, and then the coil is sealed with a cured product of the resin composition. The coil parts can be manufactured by removing them from the molding die.

  The conditions for performing injection molding using the epoxy resin composition for injection molding of the present invention are not particularly limited, but as specific conditions, cylinder temperature: normal temperature to 90 ° C, nozzle temperature: 90 to 110 ° C, The injection pressure is about 120 to 200 MPa. Moreover, it is preferable that the heating temperature in the case of hardening shall be 170-200 degreeC. The time required for curing depends on the composition of the resin composition to be used and the curing temperature, but the curing can be completed in about 60 to 180 seconds. The coil component of the present invention thus obtained is excellent in crack resistance and thermal conductivity and has high reliability.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

The material compounds (trade names) used in the production of the following examples and comparative examples will be described below.
[Epoxy resin]
(A) Solid epoxy resin (bisphenol A type epoxy resin (solid or semi-solid))
Epicron 1055: manufactured by DIC, trade name, epoxy equivalent 450, softening point 64-74 ° C
Epicron 860: DIC Corporation, trade name, epoxy equivalent 245, semi-solid Epicron 2055: DIC Corporation trade name, epoxy equivalent 630, softening point 80-90 ° C
Epicron 3055: DIC Corporation, trade name, epoxy equivalent 780, softening point 91-100 ° C
(Other epoxy resins)
EPPN-502H: polyfunctional epoxy resin, manufactured by Nippon Kayaku Co., Ltd., trade name, epoxy equivalent 170, softening point 60-76 ° C
CNE-200EL: Ortho-cresol novolak type epoxy resin (hereinafter referred to as “OCN epoxy resin” if necessary), manufactured by Changchun Epoxy Co., Ltd., trade name, epoxy equivalent 200, softening point 70-78 ° C.

[Curing agent]
(B) Solid phenol resin curing agent (polyfunctional phenol (b))
MEH-7500: Phenol-hydroxybenzaldehyde resin in which R is a hydrogen atom in the above formula (1), manufactured by Meiwa Kasei Co., Ltd., trade name, hydroxyl group equivalent 100, softening point 107-113 ° C
(Other solid phenolic resin curing agents)
BRG-556: Novolac type phenol resin, Showa Polymers, trade name, hydroxyl equivalent 105, softening point 77-82 ° C

[Curing accelerator]
((D) Dimethylurea curing accelerator)
U-CAT3512T: dimethylurea compound, manufactured by San Apro, trade name (other curing accelerator)
CllZ: Imidazole-based curing accelerator, manufactured by Shikoku Kasei Co., Ltd., trade name [Others]
(C) Silica Silica T: Crystalline silica, manufactured by Fukushima Ceramics Co., Ltd., trade name, average particle size: 25-30 μm, maximum particle size: less than 150 μm S-210: fused spherical silica, manufactured by Micron, trade name, average particle size 25-30 μm, maximum particle size: 75 μm

[Example 1]
11 parts by mass of epiclone 1055 as a bisphenol A type solid epoxy resin, 3 parts by mass of MEH-7500 as a polyfunctional phenol (b), 85 parts by mass of silica T as crystalline silica, and U-CAT3512T as a dimethylurea curing accelerator 0.3 part by mass, 0.3 part by mass of S-510 (manufactured by Chisso Corp., trade name) as a silane coupling agent, and 0.2 of Luvax-0321 (manufactured by Nippon Seiki Co., Ltd., trade name) as a release agent A mass part was prepared and melt-kneaded to prepare an epoxy resin composition for injection molding. The kneading was performed at a temperature of 100 ° C. and 40 rpm for 10 minutes.

[Example 2]
Example 1 except that 11 parts by mass of Epicron 1055 and 9.9 parts by mass of Epicron 1055 (average epoxy equivalent: 420) were used instead of 11 parts by mass of Epicron 1055 as the bisphenol A type solid epoxy resin. In the same manner as above, the materials were melted and kneaded to prepare an epoxy resin composition for injection molding.

[Example 3]
As bisphenol A type solid epoxy resin, instead of using 11 parts by mass of Epicron 1055, 10 parts by mass of Epicron 1055 and 1 part by mass of Epicron 2055 (average epoxy equivalent: 480) were used, as in Example 1. An epoxy resin composition for injection molding was prepared by melt kneading.

[Example 4]
Instead of using 85 parts by mass of silica T as crystalline silica, 75 parts by mass of silica T as crystalline silica and 11 parts by mass of S-210 as fused spherical silica (ratio of crystalline silica in silica: 87.2% by mass) are used. Except for the above, melt-kneading was conducted in the same manner as in Example 1 to prepare an epoxy resin composition for injection molding.

[Example 5]
Instead of using 3 parts by mass of polyfunctional phenol (b) MEH-7500 as a solid phenolic resin curing agent, 2.1 parts by mass of MEH-7500 and 0.9 parts by mass of novolac-type phenolic resin BRG-556 (curing agent The mixture was melt-kneaded in the same manner as in Example 1 except that the ratio of MEH-7500 in (70% by mass) was used to prepare an epoxy resin composition for injection molding.

[Example 6]
An epoxy resin composition for injection molding was prepared by melting and kneading in the same manner as in Example 1 except that 82 parts by mass of S-210 was used as fused spherical silica instead of crystalline silica.

[Comparative Example 1]
Instead of using 3 parts by mass of polyfunctional phenol (b) MEH-7500 as a solid phenolic resin curing agent, 1.8 parts by mass of MEH-7500 as polyfunctional phenol (b) and BRG-556 as a novolac type phenolic resin Was melt kneaded in the same manner as in Example 1 except that 1.2 parts by mass (ratio of MEH-7500 in the curing agent: 60% by mass) was used to prepare an epoxy resin composition for injection molding.

[Comparative Example 2]
Example 1 except that 5.5 parts by mass of epiclone 1055 and 5.5 parts by mass of epiclone 2055 (average epoxy equivalent: 540) were used as the bisphenol A type solid epoxy resin instead of using 11 parts by mass of epiclone 1055. In the same manner as above, melt-kneading was performed to prepare an epoxy resin composition for injection molding.

[Comparative Example 3]
As a bisphenol A type solid epoxy resin, an epoxy resin composition for injection molding was prepared by melt-kneading in the same manner as in Example 1 except that 11 parts by mass of Epicron 2055 was used instead of 11 parts by mass of Epicron 1055. .

[Comparative Example 4]
Example 1 except that instead of using 11 parts by mass of Epicron 1055 as the bisphenol A type solid epoxy resin, 3.1 parts by mass of Epicron 860 and 7.9 parts by mass of Epicron 1055 (average epoxy equivalent: 355) were used. In the same manner as above, melt-kneading was performed to prepare an epoxy resin composition for injection molding.

[Comparative Example 5]
Instead of bisphenol A type solid epoxy resin, 7 parts by mass of polyfunctional epoxy resin EPPN-502H and 3 parts by mass of orthocresol novolac type epoxy resin CNE-200EL were used, and MEH-7500 used as polyfunctional phenol (b) An epoxy resin composition for injection molding was prepared by melt-kneading in the same manner as in Example 1 except that the blending amount was changed from 3 parts by mass to 4 parts by mass.

[Comparative Example 6]
Instead of bisphenol A type solid epoxy resin, 2 parts by mass of polyfunctional epoxy resin EPPN-502H and 4 parts by mass of orthocresol novolac type epoxy resin CNE-200EL are used as polyphenol (b) as a solid phenol resin curing agent. Instead of using 3 parts by mass of MEH-7500, 3 parts by mass of novolac-type phenol resin BRG-556 was used, and melt-kneaded in the same manner as in Example 1 to prepare an epoxy resin composition for injection molding. .

[Comparative Example 7]
As a solid phenol resin curing agent, melt kneading was carried out in the same manner as in Example 1 except that 3 parts by mass of novolak type phenol resin BRG-556 was used instead of 3 parts by mass of MEH-7500 of polyfunctional phenol (b). Thus, an epoxy resin composition for injection molding was prepared.

[Comparative Example 8]
An epoxy resin composition for injection molding was prepared by melt-kneading in the same manner as in Example 1 except that 0.1 part by mass of the imidazole-based curing accelerator CllZ was used instead of the dimethylurea-based curing accelerator.

[Comparative Example 9]
As a bisphenol A type solid epoxy resin, an epoxy resin composition for injection molding was prepared by melt-kneading in the same manner as in Example 1 except that 11 parts by mass of Epicron 1055 was used instead of 11 parts by mass of Epicron 1055. did.

[Comparative Example 10]
As a bisphenol A type solid epoxy resin, an epoxy resin composition for injection molding was prepared by melt-kneading in the same manner as in Example 1 except that 11 parts by mass of Epicron 860 was used instead of 11 parts by mass of Epicron 1055. did.

(Evaluation method)
Next, for the epoxy resin composition for injection molding obtained in each of the above Examples and Comparative Examples, spiral flow, elevated flow viscosity, glass transition temperature, thermal expansion coefficient, bending strength and bending elastic modulus were measured. The characteristics were evaluated. Furthermore, coil parts are manufactured by injection molding using the epoxy resin composition for injection molding obtained in each of the above examples and comparative examples, and the unfilling rate and crack rate are determined by appearance inspection, and the moldability is evaluated. did.

(Spiral flow [cm])
The mold temperature was 175 ° C., the resin charge was 25 g, the plunger pressure was 75 kgf / cm ² , and the curing time was 120 seconds.
(Elevated flow viscosity [Pa · s])
The nozzle length was 1.0 mm, the nozzle radius was 0.25 mm, the temperature was 175 ° C., and the plunger pressure was 10 kgf / cm ² .
(Glass transition temperature [° C])
In the TMA method, the temperature was raised from room temperature to 200 ° C. with a hardness of 5 ° C./min, and the glass transition temperature was measured.

(Coefficient of thermal expansion [× 10 ⁻⁵ / ° C.])
In the TMA method, the temperature was increased from room temperature to 200 ° C. at a rate of 5 ° C./min, and the coefficient of thermal expansion was measured.
(Thermal conductivity [W / m · K])
It measured by the hot wire method (thin wire heating method) using thermal conductivity measuring machine QTM-500 (made by Kyoto Electronics Industry Co., Ltd.).
(Bending strength [MPa])
The bending strength at 25 ° C. was measured according to JIS K 6911.
(Bending elastic modulus [GPa])
The flexural modulus at 25 ° C. was measured according to JIS K 6911.

(Formability)
A body formed by winding a copper wire having a diameter of 0.5 mm on a bobbin having a main body diameter of 60 mm and a length of 100 mm, has a length of 64 mm, a length of 104 mm, and a thickness of 2 mm. A stator core (coil) obtained by being housed in a metal frame made of SUS was inserted into a core of a molding die, and then the upper die was closed. Then, using an injection molding machine set at a cylinder temperature of 90 ° C., a nozzle temperature of 100 ° C., and an injection pressure of 150 MPa, the injection molding epoxy resin compositions prepared in the above examples and comparative examples were injected into the molding die. , 180 ° C,
Curing was performed under a condition of 120 seconds to form a coil component in which the stator core was sealed with an epoxy resin. The appearance of 100 obtained molded products was visually inspected to examine the unfilled and crack occurrence rates.

  The compositions and evaluation results of the epoxy resin compositions for injection molding produced in the above Examples and Comparative Examples are shown in Table 1 for the Examples and Table 2 for the Comparative Examples.

As is apparent from Tables 1 and 2, the comparative epoxy resin composition using a polyfunctional epoxy resin having an average epoxy equivalent weight of less than 400 or an orthocresol novolak type epoxy resin has no problem in mechanical strength but has crack resistance. Similarly, in the epoxy resin composition of the comparative example using the bisphenol A type solid epoxy resin as well, it is found that if the average epoxy equivalent is less than 400, the crack resistance is inferior.
Moreover, in the epoxy resin composition of the comparative example whose content of polyfunctional phenol resin (b) in a hardening | curing agent is less than 70 mass%, it turns out that it is inferior to crack resistance with the fall of mechanical strength. Furthermore, it can be seen that good thermal conductivity is obtained when 75 to 90% by mass of silica is contained in the total resin composition and 75% by mass or more of crystalline silica is contained in the total silica.

  Compared to such a comparative example, the epoxy resin composition of the example that satisfies the requirements of the epoxy resin composition for injection molding of the present invention is excellent in injection moldability by having sufficient fluidity, and further its curing It can be seen that the product is excellent in thermal conductivity and crack resistance.

Claims (2)

(A) a solid epoxy resin containing as a main component a bisphenol A type solid epoxy resin having an average epoxy equivalent weight in the range of 400 to 490;
(B) a solid phenol resin curing agent containing a polyfunctional phenol resin having a polycondensation unit of phenols and benzaldehydes and / or hydroxybenzaldehydes in a proportion of 70% by mass or more based on the total amount of the curing agent;
(C) silica having a maximum particle size of 150 μm or less and an average particle size of 15 to 30 μm ;
(D) a dimethylurea curing accelerator;
(E) an epoxy silane coupling agent;
The as essential components, the sealing of the resin composition the total amount of the coil by the (C) silica for molding epoxy resin composition exiting morphism ing contained in a proportion of 75 to 90 wt% injection molding Coil parts obtained as a result . The coil component according to claim 1, wherein the (C) silica contains 75% by mass or more of crystalline silica based on the total amount of silica.