JPWO2013161606A1 - Epoxy resin composition, resin sheet, cured product, and phenoxy resin - Google Patents

Abstract

The epoxy resin composition comprises (a) an epoxy resin, (b) a curing agent, and (c) the following general formula (1); Means a biphenylene skeleton represented by the following formula (3), Y represents a biphenylene skeleton represented by the following formula (2), Z represents a hydrogen atom or a glycidyl group, n means a number representing a repeating unit. [In the formula (2), R1 to R8 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.] A non-crystalline phenoxy resin having a weight average molecular weight of 10,000 to 200,000. The component (a) contains a crystalline epoxy resin having a mesogenic group within a range of 5 to 100% by weight with respect to the total amount of the component (a).

Description

  The present invention relates to an epoxy resin composition used in the field of electronic materials, a resin sheet and a cured product using the epoxy resin composition, and a phenoxy resin used in the epoxy resin composition.

  Epoxy resins are widely used in electronic parts, electrical equipment, automobile parts, FRP, sports equipment and the like because they are excellent in adhesiveness, heat resistance, and moldability. In particular, in recent years, it is one of materials that have attracted much attention in the field of electronic materials (for example, Non-Patent Document 1).

  In the field of electronic materials, there is a problem that the chip generates heat due to the high integration of electronic circuits and the increase in power to be handled, and that heat causes signal errors and failures. It has become a challenge. In order to solve this problem, a ceramic substrate has been conventionally used. However, this has the disadvantage that the workability and productivity are very poor and the cost is high. For this reason, metal base substrates, etc., in which an insulating layer made of a resin or the like is disposed on a metal base, and wiring and mounting are further provided thereon, have been proposed and sold. Although this metal base substrate has ensured a certain market, the resin used is required to have higher thermal conductivity when handling severer conditions, specifically, high voltage or large current.

  In order to improve the thermal conductivity of the epoxy resin, in order to improve the thermal conductivity of the resin itself, a method has been proposed in which an orientation is formed in the resin in the process of curing the epoxy resin to increase the thermal conductivity (for example, Non-patent document 2). However, highly oriented epoxy resins have strong crystallinity, and the monomer is likely to precipitate as crystals in the state of varnish dissolved in a solvent, so that a uniform resin composition cannot be obtained and there is a concern of causing poor curing. is there. In addition, an epoxy resin composition containing an epoxy resin monomer having a biphenyl group or a biphenyl derivative, a dihydric or higher phenol having a hydroxyl group disposed at least in the ortho position, and a curing accelerator has also been proposed (for example, Patent Document 1). The cured product using this epoxy resin composition has improved thermal conductivity, but no specific solution has been shown for the problem of crystal precipitation in the varnish state.

Japan Institute of Electronics Packaging Printed Circuit Technology Handbook 3rd Edition (2006) Grinding, No. 55 (2012), p32-37

JP 2003-137971 A

  As described above, in order to ensure the orientation in the cured product, the resin having high thermal conductivity has a highly symmetrical molecular design, and the monomer has strong crystallinity. For this reason, even if the resin is dissolved in the solvent, the crystal component remains undissolved and there is a concern that a curing failure may occur during curing. Accordingly, an object of the present invention is to provide a resin composition having no thermal precipitation in the state of varnish dissolved in a solvent and having excellent thermal conductivity in the state of a cured product.

  In order to solve the above problems, the present inventors have intensively studied to increase the solubility of the epoxy resin in a varnish state, and as a result, by adding an amorphous phenoxy resin having a specific structure to the epoxy resin. The inventors have found that the precipitation of epoxy resin crystals in the varnish can be prevented. In addition, although the above amorphous phenoxy resin has a highly symmetrical structure, it becomes a uniform resin solution without precipitating crystals in the varnish. It has also been found that phenoxy resin exhibits higher thermal conductivity than general-purpose phenoxy resin.

That is, the epoxy resin composition of the present invention comprises the following components (a) to (c):
(A) epoxy resin,
(B) a curing agent, and (c) an amorphous phenoxy resin having a weight average molecular weight represented by the following general formula (1) in the range of 10,000 to 200,000,
Is an epoxy resin composition containing In this epoxy resin composition, the component (a) contains a crystalline epoxy resin having a mesogenic group within a range of 5 to 100% by weight based on the total amount of the component (a). ) Component is contained within a range of 5 to 90 parts by weight with respect to 100 parts by weight of the total solid content in the components (a) and (c).

［式（１）中、Ｘは、下記式（２）で表されるビフェニレン骨格又は下記式（３）で表されるナフタレン骨格を意味し、Ｙは、下記式（２）で表されるビフェニレン骨格を意味し、Ｚは、水素原子又はグリシジル基を意味し、ｎは繰り返し単位を表す数を意味する。］

[In formula (1), X means a biphenylene skeleton represented by the following formula (2) or a naphthalene skeleton represented by the following formula (3), Y represents a biphenylene represented by the following formula (2) Z means a hydrogen atom or a glycidyl group, and n means a number representing a repeating unit. ]

［式（２）中、Ｒ_１〜Ｒ_８は、それぞれ独立して水素原子又は炭素数１〜４の直鎖もしくは分岐鎖のアルキル基を意味する。］

[In Formula (2), R < ₁ > -R < ₈ > means a hydrogen atom or a C1-C4 linear or branched alkyl group each independently. ]

  In the epoxy resin composition of the present invention, the mesogenic group may be a biphenylene group.

  In the epoxy resin composition of the present invention, the mesogenic group may be a naphthalene group.

  In the epoxy resin composition of the present invention, the component (c) may be an amorphous phenoxy resin in which X and Y in the formula (1) have a biphenylene skeleton represented by the formula (2). .

In the epoxy resin composition of the present invention, in the formula (1), at least four of R _{1 to} R ₈ in the formula (2) may be an alkyl group having 4 or less carbon atoms, and the rest May be a biphenylene skeleton in which is a hydrogen atom.

In the epoxy resin composition of the present invention, in the formula (1), Y may be an unsubstituted biphenylene skeleton in which all of R _{1 to} R ₈ in the formula (2) are hydrogen atoms.

  In the epoxy resin composition of the present invention, in the formula (1), X may be a tetraalkylbiphenylene group in which an alkyl group having 4 or less carbon atoms is substituted at the 3,3′-position and the 5,5′-position. , Y may be an unsubstituted biphenylene group.

  In the epoxy resin composition of the present invention, the component (c) may be an amorphous phenoxy resin in which X in the formula (1) has a naphthalene skeleton represented by the formula (3).

In the epoxy resin composition of the present invention, in the formula (1), X may be a naphthalene skeleton having a single bond at each of the 1-position and the 6-position, and Y is R ₁ to R ₁ in the formula (2). An unsubstituted biphenylene skeleton in which all of R ₈ are hydrogen atoms may be used.

The epoxy resin composition of the present invention further comprises the following components (d),
(D) inorganic filler,
May be contained.

The epoxy resin composition of the present invention further comprises the following components (e),
(E) solvent,
May be contained.

  The resin sheet of the present invention is formed by forming any of the above epoxy resin compositions into a film.

  The cured product of the present invention is obtained by curing any of the above epoxy resin compositions.

  The phenoxy resin of the present invention has a tetramethylbiphenylene group substituted with a methyl group at the 3,3 ′ and 5,5 ′ positions, and an unsubstituted biphenylene group, and has a weight average molecular weight of 10,000 to 200,000. Is within the range.

  In the phenoxy resin of the present invention, the molar ratio of the tetramethylbiphenylene group substituted with a methyl group at the 3,3′-position and the 5,5′-position to the unsubstituted biphenylene group may be about 1: 1.

  The epoxy resin composition of the present invention comprises a combination of a crystalline epoxy resin having a mesogenic group and an amorphous phenoxy resin represented by the formula (1), so that the epoxy resin is solubilized in a solvent and varnished. It is possible to impart excellent thermal conductivity to the cured product while preventing precipitation of crystals therein. That is, by blending the amorphous phenoxy resin represented by the formula (1), the crystalline epoxy resin having a mesogenic group is solubilized, and a uniform resin composition can be obtained in a varnish state. Further, by applying and drying, molding into a resin sheet or the like can be easily performed. Moreover, the hardened | cured material which hardened this epoxy resin composition has the outstanding heat conductivity. Therefore, the epoxy resin composition of the present invention can provide molded products and cured products such as a curable resin sheet, a curable high heat dissipation resin sheet, an insulating sheet, a prepreg, and an adhesive film excellent in thermal conductivity.

  The epoxy resin composition of the present embodiment contains the components (a) to (c). Hereinafter, each component will be described.

<(I) Component: Epoxy resin>
Examples of the component (a) epoxy resin include biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and o-cresol novolac. Exemplified epoxy resins with two or more epoxy groups in the molecule such as epoxy resin, biphenyl novolac epoxy resin, triphenylmethane epoxy resin, dicyclopentadiene epoxy resin, alicyclic epoxy resin, brominated epoxy resin can do. These epoxy resins can be used alone or in combination of two or more.

  The component (a) preferably contains a crystalline epoxy resin having a mesogenic group within a range of 5 to 100% by weight based on the total amount of the component (a). (I) If the content of the crystalline epoxy resin having a mesogenic group in the component is less than 5% by weight, the thermal conductivity of the cured product may be lowered. Here, the crystalline epoxy resin having a mesogenic group is a solid epoxy resin having a softening point of 40 ° C. or higher. By using a crystalline epoxy resin having a mesogenic group, excellent thermal conductivity can be imparted to the cured product. As the mesogenic group, for example, a biphenylene group or a naphthalene group is preferable. Therefore, the biphenyl type epoxy resin and the naphthalene type epoxy resin are preferable as the crystalline epoxy resin having a mesogenic group. The crystallinity means that an endothermic peak temperature based on the melting point can be confirmed in DSC (differential scanning calorimetry). Specific examples of the crystalline epoxy resin having a mesogenic group include Nippon Steel & Sumikin Chemical Co., Ltd. GK-3007 (biphenol aralkyl type epoxy resin), Mitsubishi Chemical Corporation YX-4000 (tetramethylbiphenol type epoxy resin), Mitsubishi Chemical YL-6121H manufactured by Nippon Kayaku Co., Ltd., NC-3000 (biphenylene aralkylphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., EPPN-501H (triphenylmethane type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. and the like can be mentioned.

  The content of the epoxy resin as the component (a) is preferably in the range of 10 to 95 parts by weight with respect to 100 parts by weight of the total solids in the components (a) and (c), for example, 30 to 90 parts. More preferably within the range of parts by weight. When the content of the epoxy resin as the component (a) is more than 95 parts by weight with respect to 100 parts by weight of the solid content, the workability of the epoxy resin composition in the B-stage state is deteriorated or the cured product becomes brittle. In some cases, the adhesive strength, heat resistance, temperature cycle resistance, etc. may decrease. When the component (a) is a crystalline epoxy resin and the above upper limit is exceeded, the solvent solubility is lowered, and it becomes difficult to form a film of the epoxy resin composition. On the other hand, when the content of the epoxy resin of component (a) is less than 10 parts by weight with respect to 100 parts by weight of the solid content, the epoxy resin composition is insufficiently cured, resulting in a decrease in adhesive strength and a decrease in heat resistance. May occur. When the component (b) is a crystalline epoxy resin, if the component is below the lower limit, the resin sheet in the B-stage state becomes hard and easily broken.

  The solid content in the components (A) and (C) is, for example, when the epoxy resin composition is a varnish containing a predetermined solvent, and uses this varnish to form a cured product such as an insulating adhesive layer. In the process, the solid content in the components (a) and (c) that remains after the solvent is removed by drying or curing is meant. Here, the varnish is a solvent containing a solvent for the purpose of reducing the viscosity of the epoxy resin composition and improving the workability. By doing so, a B-stage resin sheet can be obtained. Moreover, after impregnating the obtained varnish in a glass cloth etc., it can obtain a prepreg by drying. The solvent is removed by these drying steps. After a cured product such as an insulating adhesive layer is finally formed, the solvent is removed by drying and heat treatment. Therefore, the content rate of the component in the epoxy resin composition of this Embodiment was prescribed | regulated using the component content rate with respect to the sum total of the solid content in (A) and (C) component. In addition, when mix | blending arbitrary components with the epoxy resin composition of this Embodiment, you may calculate on the basis of the solid content of the whole epoxy resin composition also including an arbitrary component. It should be noted that the degree of solvent removal can also control the remaining solvent in the design within the manufacturing process.

<(B) component: curing agent>
The component (b) curing agent is blended for the purpose of curing the epoxy resin. When an insulating layer, an adhesive layer or a resin film is produced from the epoxy resin composition, sufficient insulation and adhesion are obtained. , Impart heat resistance, mechanical strength, etc. As the (b) component curing agent used in the present embodiment, an imidazole curing agent or a non-imidazole curing agent can be used.

  The imidazole curing agent is preferably composed only of an imidazole compound. The imidazole curing agent can relatively easily handle the epoxy resin composition after blending, for example, the viscosity increase of the epoxy resin composition can be suppressed. Examples of the imidazole compound include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, and 2-phenyl. Examples include -4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

  Among the imidazole compounds, 2-phenyl-4,5-dihydroxymethylimidazole is most preferably used. 2-Phenyl-4,5-dihydroxymethylimidazole is a high-potential curing agent, and does not proceed with a curing reaction in the drying process when preparing a B-stage resin sheet, and is stable during long-term storage. Has excellent characteristics.

  An imidazole compound is usually often blended as a curing accelerator in a resin composition containing an epoxy resin as a main component. However, in the epoxy resin composition of the present embodiment, when an imidazole-based curing agent is used, since no curing agent component other than the imidazole compound is used, the epoxy resin composition is subjected to anionic polymerization that proceeds from the imidazole compound. Can be cured. From such reaction characteristics, in the epoxy resin composition of the present embodiment, the imidazole compound can function as a curing agent, and compared with a reaction system in which an addition type curing agent component is blended, the blending as a curing agent. The amount can be kept low. As described above, since the imidazole compound is a catalyst type curing agent, for example, if an addition type curing agent component such as dicyandiamide or a novolac type phenol resin is present, the addition type curing agent component and the epoxy resin react preferentially. However, the condensation reaction with the epoxy resin alone is unlikely to occur.

  (B) The content when using an imidazole-based curing agent composed of an imidazole compound as the component is, for example, 0.01 to 10 parts by weight with respect to 100 parts by weight of the total solids in the components (A) to (C). Is preferably in the range of 0.01 to 5 parts by weight. When the content of the imidazole curing agent is more than 10 parts by weight, there is a risk of inducing a halogen element derived from the epoxy resin as a halogen ion. On the other hand, if the content of the imidazole-based curing agent is less than 0.01 parts by weight, the curing reaction does not proceed sufficiently, the adhesive strength is reduced, or the curing time is prolonged and the usability is reduced. There is.

  On the other hand, examples of the non-imidazole-based curing agent include those known as epoxy resin curing agents such as novolak-type phenolic resin, dicyandiamide, diaminodiphenylmethane, and diaminodiphenylsulfone. The non-imidazole curing agent is preferably blended so that the equivalent ratio ((b) / (b)) is 0.5 to 1.5 with respect to the epoxy resin of component (b). Generally, when using a phenol resin-type hardening | curing agent, the range of 0.8-1.2 is good, and when using an amine-type hardening | curing agent, it is good to set it as the range of 0.5-1.0.

  When a non-imidazole curing agent is used, it is preferable to contain a curing accelerator in addition to the components (A) to (C). As a hardening accelerator, organic phosphorus compounds, such as triphenylphosphine, imidazoles, such as 2-phenylimidazole and 2-ethyl-4-methylimidazole, etc. can be used, for example. The blending ratio is appropriately selected according to the required curing time, but is generally 0.01 to 3.0 with respect to 100 parts by weight of the total solids in the components (A) to (C). Within the range of parts by weight is preferred.

<(C) Amorphous phenoxy resin>
The amorphous phenoxy resin as the component (c) has a biphenylene skeleton or a naphthalene skeleton. Amorphous phenoxy resin prevents precipitation of crystals when the epoxy resin composition is in a varnish state and maintains a dissolved state in an organic solvent, and from the epoxy resin composition to an insulating layer, an adhesive layer, and a resin film. It is a component which improves the flexibility at the time of producing.

  The amorphous phenoxy resin having a biphenylene skeleton or a naphthalene skeleton is represented, for example, by the following general formula (1). In formula (1), X means a biphenylene skeleton represented by the following formula (2) or a naphthalene skeleton represented by the following formula (3), and Y represents a biphenylene skeleton represented by the following formula (2). Z represents a hydrogen atom or a glycidyl group, and n represents a number representing a repeating unit.

In formula (2), R _{1 to} R ₈ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. In the amorphous phenoxy resin of component (c), the ratio of X and Y is about 1: 1, but there may be a slight difference in the contents of X and Y. The molecular weight of the component (c) amorphous phenoxy resin is designed by the molar ratio of the starting compounds, and the desired product is generally obtained while controlling the reaction temperature and reaction time. It can be designed so that the end of the main chain is an epoxy group or a phenolic hydroxyl group depending on the molar ratio of the raw materials used. The non-crystalline phenoxy resin represented by the general formula (1) is substantially the same compound as the epoxy resin, but is called because it has different properties due to a difference in molecular weight. That is, the epoxy resin refers to those having a small molecular weight, and the phenoxy resin refers to those having a large molecular weight. Although there is no clear boundary, generally those having a weight average molecular weight of 10,000 or more are called phenoxy resins. The phenoxy resin is distinguished from the epoxy resin because the characteristic as a thermoplastic resin appears more strongly than the characteristic as a thermosetting resin because there are few epoxy groups as reaction points with respect to the molecular size. Epoxy resins and phenoxy resins are produced in various molecular weights depending on the purpose. In addition, since the average molecular weight of the epoxy resin of patent document 1 is about 300-400, according to the said classification, it corresponds to an epoxy resin.

  The weight average molecular weight of the (C) component amorphous phenoxy resin is, for example, in the range of 10,000 to 200,000, and more preferably in the range of 20,000 to 100,000. When the weight average molecular weight of the amorphous phenoxy resin is less than 10,000, the self-film forming property is poor, and the sheet or film becomes fragile and is difficult to handle. Moreover, when a weight average molecular weight exceeds 200,000, the problem that an amorphous phenoxy resin becomes difficult to melt | dissolve with respect to a solvent, and the problem that the viscosity of a resin solution becomes high generate | occur | produce. In addition, the weight average molecular weight here is a value in terms of polystyrene by GPC (gel permeation chromatography) measurement.

Preferable examples of the amorphous phenoxy resin of component (c) include those in which X and Y in formula (1) are both a biphenylene skeleton represented by formula (2). In this case, at least for X, in Formula (2), at least four of R _{1 to} R ₈ are preferably alkyl groups having 4 or less carbon atoms, and the rest are hydrogen atoms, and Y is the same as X Or an unsubstituted biphenyl skeleton in which R _{1 to} R ₈ in formula (2) are all hydrogen atoms. That is, as the non-crystalline phenoxy resin of the component (c), for example, X in the formula (1) is in the 3,3 ′ position and the 5,5 ′ position, or the 2,2 ′ position and the 6,6 ′ position. And a biphenylene skeleton in which an alkyl group having 4 or less carbon atoms is substituted at each position, and Y is the same as X, for example, in the 3,3 ′ position and the 5,5 ′ position, or the 2,2 ′ position and 6, It is preferably a biphenylene skeleton in which an alkyl group having 4 or less carbon atoms is substituted at the 6 ′ position or an unsubstituted biphenylene skeleton, and the alkyl group having 4 or less carbon atoms is a methyl group, Further, a phenoxy resin having a weight average molecular weight in the range of 10,000 to 200,000 is more preferable. Furthermore, while the non-crystalline phenoxy resin of component (c) is prevented from solidifying or crystallizing in the solvent by introducing a biphenylene skeleton having a substituent, the non-substituted (all hydrogen From the viewpoint of introducing a larger number of (substituted) biphenylene skeletons, X in the formula (1) is 3,3 ′, 5,5′-tetramethylbiphenylene group, and Y is an unsubstituted biphenylene group. Particularly preferred.

As another preferred example of the amorphous phenoxy resin of component (c), X in the formula (1) is a naphthalene skeleton represented by the formula (3), and Y is represented by the formula (2). And those having a biphenylene skeleton. In this case, X is preferably an asymmetrical position of the single bond of the naphthalene skeleton in Formula (3), and Y is an unsubstituted group in which R _{1 to} R ₈ in Formula (2) are all hydrogen atoms. The biphenyl skeleton is preferable. Here, as a specific example of the one in which the position of the single bond of the naphthalene skeleton is asymmetric, in the formula (3), one having a single bond at the 1-position and 6-position, or the 1-position and the 7-position of the naphthalene skeleton is preferable. Thus, when the position of the single bond of the naphthalene skeleton is asymmetric, the molecular chain is difficult to be oriented due to structural hindrance, so that a liquid phenoxy resin soluble in a solvent can be obtained. On the other hand, for example, when a highly symmetrical product such as a single bond at each of the 2-position and the 7-position in the formula (3) is used, the phenoxy resin is solidified or crystallized in the solvent, and the liquid phenoxy It becomes difficult to obtain a resin. Accordingly, the non-crystalline phenoxy resin of component (c) is preferably one in which X in formula (1) is a naphthalene skeleton having a bond at an asymmetric position, and Y is an unsubstituted biphenylene skeleton. More preferred is a phenoxy resin having a weight average molecular weight in the range of 10,000 to 200,000.

  The content of the (a) component amorphous phenoxy resin is preferably in the range of 5 to 90 parts by weight, for example, with respect to 100 parts by weight of the total solids in (a) and (c), A range of 10 to 70 parts by weight is more preferable. When the content of the amorphous phenoxy resin is more than 90 parts by weight with respect to the total of 100 parts by weight of the solid content, the viscosity of the varnish increases, and the workability and adhesion as an insulating layer and an adhesive layer are increased. May deteriorate, the surface condition may deteriorate, and the heat resistance may be reduced. Moreover, when it is set as a resin sheet, it becomes hard and it becomes easy to break, and handling property falls. On the other hand, if the content of the amorphous phenoxy resin is less than 5 parts by weight with respect to the total solid content of 100 parts by weight, crystals of the epoxy resin of the component (a) precipitate in the varnish state, resulting in poor curing. Cause it to happen.

  In the epoxy resin composition of the present embodiment, the (a) component epoxy resin containing the crystalline epoxy resin having a mesogenic group is blended with the (c) component amorphous phenoxy resin, thereby combining the varnish. While effectively preventing crystal formation in this state, excellent thermal conductivity can be imparted to the cured product. For this purpose, the compounding ratio of the component (c) to the crystalline epoxy resin having a mesogenic group of the component (a) in the epoxy resin composition of the present embodiment [crystals having a mesogenic group at (ha) / (a) For example, the range of 0.35 to 10 is preferable. When the blending ratio [the crystalline epoxy resin having a mesogenic group at (C) / (I)] is less than 0.35, the effect of suppressing the precipitation of crystals in the varnish state is lowered. On the other hand, when the said mixture ratio exceeds 10, it becomes a cause of the fall of the solubility to the organic solvent of an epoxy resin composition.

  The amorphous phenoxy resin represented by the general formula (1) is represented by, for example, an epoxy compound having two epoxy groups in one molecule represented by the following general formula (4) and the following general formula (5). Or a method of reacting a compound having two aromatic hydroxyl groups in one molecule in the presence of a polymerization catalyst, or two aromatic hydroxyl groups in one molecule represented by the following general formula (5) It can be produced by a publicly known and commonly used method of reacting a compound having an epihalohydrin with an alkali metal hydroxide. In addition, although it does not restrict | limit especially as epihalohydrin used for the synthesis | combination of an amorphous phenoxy resin, For example, epichlorohydrin is preferable. Moreover, there is no restriction | limiting in particular as an alkali metal hydroxide, For example, sodium hydroxide is preferable.

  X and Y in the above formulas (4) and (5) have the same meaning as described above. Here, as an epoxy compound which has two epoxy groups in 1 molecule represented by General formula (4), Mitsubishi Chemical Corporation YX-4000 (tetramethylbiphenol type epoxy resin), Mitsubishi Chemical Corporation make, for example. YL-6121H etc. are mentioned.

<Optional component>
In addition to the above essential components, for example, a solvent, a rubber component, a fluorine-based or silicone-based antifoaming agent, a leveling agent, and the like can be added to the epoxy resin composition of the present embodiment as necessary. Moreover, from the viewpoint of improving the adhesion to members such as a metal substrate and copper wiring, for example, an adhesion imparting agent such as a silane coupling agent or a thermoplastic oligomer can be added. Furthermore, you may add an inorganic filler and an organic filler to the epoxy resin composition of this Embodiment. Examples of the inorganic filler include alumina, silica, boron nitride, aluminum nitride, silicon nitride, calcium carbonate, magnesium carbonate and the like. Examples of the organic filler include silicon powder, nylon powder, acrylonitrile-butadiene-based crosslinked rubber, and the like. About these fillers, 1 type (s) or 2 or more types can be used. In addition, the epoxy resin composition of the present embodiment can be blended with a colorant such as phthalocyanine / green, phthalocyanine / blue, or carbon black, if necessary.

  Here, examples of the alumina as the inorganic filler include crystalline alumina, fused alumina, and the like. Among these, crystalline spherical alumina powder is particularly preferable. Crystalline alumina is excellent in the effect of increasing the thermal conductivity as compared with fused alumina. In addition, the use of spherical alumina also has an effect of lowering the viscosity when used as a varnish or the melt viscosity when used as a resin film as compared with crushed alumina. From the viewpoint of achieving high thermal conductivity by close packing, it is preferable that the sphericity of the spherical alumina powder is 95% or more.

  The maximum particle size of the spherical alumina powder has a great influence on the thermal conductivity and insulation. A conductive path when a voltage is applied is formed on the surface of the spherical alumina powder. Therefore, if the maximum particle diameter is set so that a plurality of spherical alumina particles can be arranged in the thickness direction of the cured product, the conductive path becomes longer and the number of insulation points between the particles increases, so that the withstand voltage increases, but heat dissipation Sex is reduced. Therefore, the maximum particle diameter of the spherical alumina powder is preferably determined in consideration of the balance between voltage resistance and heat dissipation.

  In the epoxy resin composition of the present embodiment, when spherical alumina powder is used as the inorganic filler, the content is preferably 50 to 95% by weight with respect to the solid content of the epoxy resin composition, and is 75 to 94. More preferably, it is% by weight. The higher the content of the spherical alumina powder in the epoxy resin composition, the higher the thermal conductivity and the lower the thermal expansion. If the content of the spherical alumina powder with respect to the solid content of the epoxy resin composition is less than 50% by weight, the effect of improving the thermal conductivity becomes insufficient, and sufficient heat dissipation may not be exhibited. On the other hand, when the content of the spherical alumina powder with respect to the solid content of the epoxy resin composition is more than 95% by weight, the viscosity when used as a varnish increases or the melt viscosity when used as an adhesive film increases. The workability, withstand voltage characteristics, and adhesiveness of the adhesive layer may be deteriorated or the surface state may be deteriorated.

[varnish]
The epoxy resin composition of the present embodiment can be prepared by mixing the above essential components and optional components. In this case, it is preferable to use a varnish containing a solvent. That is, the epoxy resin composition of the present embodiment may be dissolved or dispersed in a predetermined solvent to form a varnish.

  Examples of solvents that can be used for the varnish include amide solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), and 1-methoxy-2-propano- Exemplified solvents such as ether solvents such as methyl, ketones such as methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclohexanone and cyclopentanone, and aromatic solvents such as toluene and xylene it can. (B) The curing agent of the component, and among the optional components added as necessary, the inorganic filler, the organic filler, the colorant, etc., are not necessarily dissolved in the solvent if they are uniformly dispersed in the solvent. It does not have to be.

  A varnish can be prepared according to the procedure shown below, for example. First, the amorphous phenoxy resin of component (c) is dissolved in a suitable solvent while stirring in a container with a stirrer. Next, the varnish can be prepared by mixing the epoxy resin of the component (A), the curing agent of the component (B), and an optional component with this solution, stirring, and dissolving or uniformly dispersing. Depending on the type of component (a) epoxy resin, an epoxy resin may be separately prepared in a solvent and mixed. As described above, the epoxy resin composition of the present embodiment is a combination of a crystalline epoxy resin having a mesogenic group and a non-crystalline phenoxy resin, whereby a varnish of a crystalline epoxy resin having a mesogenic group is used. The precipitation of crystals can be suppressed. Therefore, it becomes possible to obtain a uniform epoxy resin composition in the state of varnish, and further, it is easy to mold the resin sheet or the like by coating and drying.

  The varnish preferably has a viscosity in the range of 1000 to 20000 Pa · s, and more preferably in the range of 2000 to 10000 Pa · s. When the viscosity of the varnish is less than 1000 Pa · s, the spherical filler is liable to settle, and unevenness and repelling during coating are likely to occur. On the other hand, when the viscosity of the varnish is larger than 20000 Pa · s, the coating property is lowered due to the decrease in fluidity, and it becomes difficult to produce a uniform coating film.

[Resin sheet / copper foil with resin sheet]
In this Embodiment, the resin sheet of a B-stage state can be formed by apply | coating the said varnish on the base film as a support material, and making it dry. Moreover, the copper foil with a resin sheet can also be formed by apply | coating the said varnish on copper foil, and making it dry. When the B-stage resin sheet (copper foil with a resin sheet) is bent, its value as a product is lost when cracks occur on the surface. Such surface cracks in the B-stage state are likely to occur when a large amount of a crystalline epoxy resin having a mesogenic group that is solid at room temperature is blended. As described above, the epoxy resin composition of the present embodiment is obtained by combining the crystalline epoxy resin having a mesogenic group and the amorphous phenoxy resin, thereby improving the flexibility of the resin sheet, and further varnishing. As a result of suppressing the precipitation of crystals therein, the generation of cracks can also be suppressed. Moreover, in this Embodiment, when only an imidazole compound is used as a hardening | curing agent, the ratio of the solid resin component which occupies for an epoxy resin composition can be restrained low. In addition, the amount of the imidazole compound as a curing agent can be reduced as compared with, for example, a case where a phenol novolac-based curing agent component is blended. Therefore, it becomes possible to mix | blend more liquid or semi-solid components at normal temperature, the softness | flexibility in a B stage state, a flexibility, and a surface crack can be prevented.

  Moreover, about the film supportability of the resin sheet or the copper foil with a resin sheet (before curing), the higher the solvent residual rate, the better the film supportability. However, if the solvent residual ratio is too high, the resin sheet or the copper foil with resin sheet (before curing) may be tacked or foamed during curing. Therefore, the solvent residual ratio is preferably 5% by weight or less. In addition, a solvent residual rate is the value calculated | required by the measurement of the net weight reduction rate of the resin sheet part at the time of drying for 60 minutes in 180 degreeC atmosphere.

  Examples of the support material used when forming the resin sheet or the copper foil with a resin sheet include polyethylene terephthalate (PET), polyethylene, copper foil, aluminum foil, release paper, and the like. The thickness of the support material can be set to, for example, 10 to 100 μm. When using metal foil, such as copper foil and aluminum foil, as the support material, the metal foil may be manufactured by, for example, an electrolytic method, a rolling method, or the like. In these metal foils, the surface on the side in contact with the insulating layer is preferably roughened from the viewpoint of enhancing the adhesion to the insulating layer.

  In addition, the resin sheet or the copper foil with a resin sheet is laminated on a base film as a support material, and then the other surface that is not in contact with the copper foil is covered with a film as a protective material and wound into a roll. Can also be saved. Examples of the protective material used at this time include polyethylene terephthalate, polyethylene, release paper, and the like. In this case, the thickness of the protective material can be in the range of 10 to 100 μm, for example.

[Cured product]
The cured product of the present embodiment is prepared by, for example, preparing the B-stage resin sheet (or copper foil with a resin sheet) from the epoxy resin composition, and then heating it to a temperature in the range of 150 ° C. to 250 ° C., for example. Can be produced by curing. The cured product thus obtained does not have crystallinity but has excellent thermal conductivity. In applications where high thermal conductivity is required, the thermal conductivity of the cured product is preferably, for example, 10 W / mK or more, and more preferably 13 W / mK or more. When the cured product has a thermal conductivity of 10 W / mK or more, it has excellent heat dissipation characteristics and can be applied to a circuit board or the like used in a high temperature environment.

[Metal-based circuit board manufacturing method]
Next, an example of a method for producing a metal base circuit board using the epoxy resin composition of the present embodiment will be described. Here, an aluminum base circuit board using an aluminum substrate is illustrated. First, after obtaining said copper foil with a resin sheet from an epoxy resin composition, this copper foil with a resin sheet is temperature-150-250 degreeC, for example, pressure 1 using a batch type vacuum press on an aluminum substrate. It adheres on the conditions of 0-30 Mpa. At this time, the resin sheet surface is brought into contact with the aluminum substrate surface, and the epoxy resin is cured by applying heat and pressure in a state where the copper foil as a support material is the upper surface, thereby being attached to the aluminum substrate. In this way, a laminate in which the resin sheet is used as an insulating adhesive layer and interposed between the copper foil layer and the aluminum substrate can be obtained. Next, by removing the copper foil at a predetermined location by etching, circuit wiring can be formed, and finally an aluminum base circuit board can be obtained. In addition, although there is no restriction | limiting in particular about the thickness of an aluminum substrate, Generally, it can be 0.5-3.0 mm, for example.

  In order to obtain an aluminum base circuit board composed of a conductor layer made of copper, an insulating adhesive layer, and an aluminum layer using the epoxy resin composition of the present embodiment, in addition to the above-described method, a releasability is imparted. After applying and drying on the PET film, the release PET is peeled off, sandwiched between an aluminum substrate and a copper foil, and cured by heating and pressing, an adhesive layer is formed on the aluminum substrate surface, and this adhesive layer A method of placing a copper foil on the substrate and curing it while heating and pressing, or a method of forming an insulating adhesive layer on the aluminum substrate surface and curing it, and then forming a copper conductor layer by copper plating, etc. May be adopted. In addition, regarding the formation of the adhesive layer at this time, any of a method of volatilizing the solvent by heating after applying the varnish, a method of applying a solventless paste, or a method of bonding the resin sheet may be used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Weight average molecular weight of phenoxy resin]
The weight average molecular weight of the phenoxy resin was analyzed using gel permeation chromatography. Specifically, the Tosoh Corporation HLC-8320 main body was used with a Tosoh Corporation column, TSK-gel GMHXL, TSK-gel GMHXL, and TSK-gel G2000H in series. Tetrahydrofuran was used as the eluent, and the flow rate was 1 ml / min. The temperature of the column chamber was 40 degrees. Detection was performed using an RI detector. The weight average molecular weight was determined using a standard polystyrene calibration curve.

[Non-volatile content of phenoxy resin solution]
The nonvolatile content of the phenoxy resin solution was obtained by weighing about 1 g of a sample in an aluminum cup, drying in a hot air circulation oven at 200 ° C. for 1 hour, and calculating the nonvolatile content based on the remaining weight without volatilization. .

[Evaluation of crystallinity of crystalline epoxy resin having mesogenic group]
The crystallinity of the crystalline epoxy resin having a mesogenic group is evaluated by adding 100 parts by weight of acetone to 100 parts by weight of the crystalline epoxy resin having a mesogenic group and then dissolving the insoluble matter and the precipitate. And dried to obtain a solid. The obtained solid was subjected to differential scanning calorimetry, and the crystallinity was evaluated based on whether or not the endothermic peak temperature based on the melting point could be confirmed.

[Thermal conductivity]
Using a predetermined amount of B-stage resin sheet, heated at 180 ° C. for 10 minutes in a compression press molding machine, taken out from the press, and further heated at 180 ° C. for 50 minutes in a dryer to give a diameter of 50 mm. A disk-shaped test piece having a thickness of 5 mm was obtained. This test piece was measured for thermal conductivity [W / m · K] at 25 ° C. by a steady method using a thermal conductivity measuring device HC-110 manufactured by EKO.

Synthesis Example 1-1
In a separable flask equipped with a stirrer, a nitrogen inlet, a reflux port equipped with a decompression device, a cooler, and an oil / water separation tank, and a separable flask equipped with an alkali metal hydroxide aqueous solution dropping port, 300 parts by weight of 1,6-dihydroxynaphthalene and 1387 of epichlorohydrin .5 parts by weight, 208.1 parts by weight of high-solve MDM were charged, heated to 60 ° C. after nitrogen purge, dissolved, and 31.1 parts by weight of 48.8% by weight sodium hydroxide aqueous solution, paying attention to heat generation Charged and reacted for 1 hour. Thereafter, the introduction of nitrogen was stopped, and 290.0 parts by weight of an aqueous solution of 48.8% by weight of sodium hydroxide was added dropwise over 8 hours under the conditions of 160 Torr and 63 ° C. When the dropping was completed, the temperature was raised to 150 ° C., and the pressure was reduced to 10 Torr to distill off epichlorohydrin and high-solve MDM. Toluene was added to the obtained resin, followed by filtration using diatomaceous earth. After washing with a 0.1 wt% sodium hydroxide aqueous solution, oil-water separation was performed to remove the aqueous phase. Further, water was added for washing, followed by oil / water separation to remove the aqueous phase. Water and toluene were removed from the obtained resin solution to obtain a 1,6-dihydroxynaphthalene diglycidyl ether type epoxy resin. The obtained epoxy resin was a brown liquid, and its epoxy equivalent was 143.8 g / eq.

Synthesis Example 1-2
To a separable flask provided with a reflux port equipped with a stirrer, a nitrogen inlet, a thermocouple, and a cooler, 61.2% of the 1,6-dihydroxynaphthalene diglycidyl ether type epoxy resin obtained in Synthesis Example 1-1 was obtained. Part by weight, 38.8 parts by weight of 4,4′-biphenol and 25 parts by weight of cyclohexanone were charged, heated to 145 ° C., dissolved, and stirred for 1 hour. Thereafter, 0.1 part by weight of tris- (2,6-dimethoxyphenyl) phosphine was charged as a reaction catalyst, and the temperature was raised to 165 ° C. The viscosity increased with the progress of the reaction, but cyclohexanone was appropriately added and stirring was continued to obtain a constant torque. The reaction was followed by gel permeation chromatography, and when the weight average molecular weight was reached, cyclohexanone was added and cooled to stop the reaction. The resulting solution was uniform and had a solid content of 30.5% by weight. The obtained phenoxy resin was a light brown liquid and had an epoxy equivalent of 5750 g / eq, a number average molecular weight of 7,800 and a weight average molecular weight of 47,600.

Synthesis Example 2-1
The synthesis was performed in the same procedure as in Synthesis Example 1-1 except that 2,7-dihydroxynaphthalene was used to obtain a diglycidyl ether type epoxy resin of 2,7-dihydroxynaphthalene. The obtained resin was a brown liquid, but had crystallinity and became a white solid. Moreover, the epoxy equivalent was 145.0 g / eq.

Synthesis Example 2-2
Synthesis example except that 56.7 parts by weight of 2,7-dihydroxynaphthalene diglycidyl ether type epoxy resin obtained in Synthesis Example 2-1 and 43.3 parts by weight of bisphenol A were prepared as an epoxy resin having a naphthalene skeleton. The reaction was terminated when the weight average molecular weight reached around 40,000 in the same procedure as in 1-2, and a solution having a solid content of 30.5% by weight was obtained. The obtained phenoxy resin was a light brown liquid, and the weight average molecular weight was 44,600.

Synthesis Example 2-3
The synthesis was performed in the same procedure as in Synthesis Example 1-1 except that 1,5-dihydroxynaphthalene was used to obtain a 1,5-dihydroxynaphthalene diglycidyl ether type epoxy resin. During the synthesis, the temperature was kept so as not to precipitate crystals. The obtained resin had crystallinity and became a white solid. Moreover, the epoxy equivalent was 149.3 g / eq.

Synthesis Example 3-1
In a 2000 ml four-necked flask, 186.0 g (1.0 mol) of 4,4′-dihydroxybiphenyl and 600 g of diethylene glycol dimethyl ether were charged, and the temperature was raised to 150 ° C. with stirring under a nitrogen stream. A solution in which 52.5 g (0.3 mol) of 4-bischloromethylbenzene was dissolved was dropped, and then the temperature was raised to 170 ° C. and reacted for 2 hours. After the reaction, it was dropped into a large amount of pure water and recovered by reprecipitation to obtain 202 g of a pale yellow crystalline resin.

Synthesis Example 3-2
115 g of the resin obtained in Synthesis Example 3-1 was dissolved in 549 g of epichlorohydrin and 82.4 g of diethylene glycol dimethyl ether, and 82.4 g of 48% sodium hydroxide aqueous solution was added dropwise at 62 ° C. under reduced pressure (about 130 Torr) over 4 hours. During this time, the generated water was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was continued for another hour. Thereafter, epichlorohydrin was distilled off, 966 g of methyl isobutyl ketone was added, and then the salt was removed by washing with water. Thereafter, 19.2 g of a 24% aqueous sodium hydroxide solution was added and reacted at 85 ° C. for 2 hours. After the reaction, filtration and washing with water were performed, and then methyl isobutyl ketone as a solvent was distilled off under reduced pressure to obtain 145 g of an epoxy resin. Epoxy equivalent was 173.0 g / eq, and hydrolyzable chlorine was 490 ppm. The obtained resin was a biphenol aralkyl type epoxy resin represented by the following formula (6). In formula (6), n means a number representing a repeating unit.

[Example 1]
To a separable flask equipped with a reflux port equipped with a stirrer, nitrogen inlet, thermocouple, and cooler, a diglycidyl ether type epoxy resin of 3,3 ′, 5,5′-tetramethylbiphenol (manufactured by Mitsubishi Chemical Corporation) YX-4000, epoxy equivalent 186, solid) 61.2 parts by weight, 4,4′-biphenol 33.9 parts by weight, cyclohexanone 25 parts by weight, heated to 145 ° C. and dissolved. Stir for 1 hour. Thereafter, 0.1 part by weight of tris- (2,6-dimethoxyphenyl) phosphine was charged as a reaction catalyst, and the temperature was raised to 165 ° C. The viscosity increased with the progress of the reaction, but cyclohexanone was appropriately added and stirring was continued to obtain a constant torque. The reaction was followed by gel permeation chromatography, and when the weight average molecular weight was reached, cyclohexanone was added and cooled to stop the reaction. The resulting solution was uniform and had a solid content of 29.7% by weight. The obtained phenoxy resin was a pale yellow liquid and had an epoxy equivalent of 11,400 g / eq, a number average molecular weight of 15,300, and a weight average molecular weight of 40,600.

(Comparative Example 1)
In place of 61.2 parts by weight of 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether type epoxy resin and 33.9 parts by weight of 4,4′-biphenol in Example 1, bisphenol A Example, except that 65.8 parts by weight of type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: YD-8125, epoxy equivalent 175, liquid) and 34.2 parts by weight of 4,4′-biphenol were used When the reaction was carried out in the same manner as in No. 1, a solid precipitated in the solution, and a phenoxy resin solution could not be obtained.

(Comparative Example 2)
Synthesis example in place of 61.2 parts by weight of diglycidyl ether type epoxy resin of 3,3 ′, 5,5′-tetramethylbiphenol and 33.9 parts by weight of 4,4′-biphenol in Example 1 Except that 62.0 parts by weight of the 2,7-dihydroxynaphthalene diglycidyl ether type epoxy resin obtained in 2-2 and 38.1 parts by weight of 4,4′-biphenol were used, the same procedure as in Example 1 was performed. As a result, a solid was precipitated in the solution, and a phenoxy resin solution could not be obtained.

[Examples 2 to 12 and Comparative Examples 3 to 6]
The raw materials and their abbreviations used for producing the epoxy resin composition and the resin film are as follows.

(A) Epoxy resin composition (a) Epoxy resin Epoxy resin (1): Bisphenol type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name; YD-825GS, epoxy equivalent 180, liquid)
Epoxy resin (2): biphenylene aralkylphenol type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: NC-3000, epoxy equivalent 275, softening point 56 ° C.)
Epoxy resin (3): Triphenylmethane type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: EPPN-501H, epoxy equivalent 170, semi-solid, softening point 60 ° C.)
Epoxy resin (4): 1,5-dihydroxynaphthalene type epoxy resin obtained in Synthesis Example 2-3 (softening point 172 ° C.)
Epoxy resin (5): biphenol aralkyl type epoxy resin obtained in Synthesis Example 3-2 (softening point 135 ° C.)
(B) Curing agent curing agent (1): 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name: Curesol 2PHz-PW)
(C) Phenoxy resin Phenoxy resin (1): Biphenol aralkyl type phenoxy resin phenoxy resin obtained in Example 1 (2): 1,6-dihydroxynaphthalene type phenoxy resin phenoxy resin obtained in Synthesis Example 1-2 ( 3): Bisphenol A type phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: YP-50)
Phenoxy resin (4): Bisphenol AF type phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: ZX-1356-2)
(D) Silane coupling agent Silane coupling agent (1): manufactured by Chisso Corporation, trade name: Siler Ace S-510

(B) Spherical filler alumina powder (1): manufactured by Admatechs, Inc., trade name: AO-802, spherical, crystallinity, maximum particle size: 10 μm, average particle size D ₅₀ ; 0.7 μm, Na ⁺ ; 1.3 ppm
Alumina powder (2): manufactured by Micron Corporation, trade name: AL10-75R, spherical, crystallinity, maximum particle diameter: 75 μm, average particle diameter D ₅₀ ; 10 μm, Na ⁺ ; 3.9 ppm
Alumina powder (3): Micron Corporation, trade name: AL35-75R, spherical, crystallinity, maximum particle size: 75 μm, average particle size D ₅₀ ; 35 μm, Na ⁺ ; 1.8 ppm

(Preparation of varnish of epoxy resin composition)
Said raw material was mix | blended in the ratio shown to Tables 1-3. First, only the phenoxy resin was stirred and dissolved in cyclohexanone in a container with a stirrer. Next, an epoxy resin and a silane coupling agent were blended in the cyclohexanone solution and heated to 80 ° C. This was cooled to room temperature and allowed to stand for 24 hours to confirm the presence or absence of crystal precipitation. In the case of no crystal precipitation, the curing agent and alumina powder were continuously blended, stirred and dispersed to prepare an epoxy resin composition varnish.

(Production of resin sheet and cured product)
The varnish obtained above was applied to a release-treated PET film (MRX-50, manufactured by Mitsubishi Chemical Corporation) having a thickness of 50 μm so that the thickness of the resin layer after drying was 200 μm, and then at 130 ° C. for 15 minutes. By drying, a B-stage resin sheet was produced. The B-stage resin sheet was cured at 180 ° C. to obtain a cured product.

  The results are shown in Tables 1-3. In the table, the blending amounts of epoxy resin, curing agent, phenoxy resin, alumina powder, silane coupling agent, and solvent (cyclohexanone) are shown in parts by weight.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment.

Claims (15)

The following (i) to (c) ingredients,
(A) epoxy resin,
(B) a curing agent, and (c) an amorphous phenoxy resin having a weight average molecular weight represented by the following general formula (1) in the range of 10,000 to 200,000,
An epoxy resin composition containing
The component (a) contains a crystalline epoxy resin having a mesogenic group within a range of 5 to 100% by weight based on the total amount of the component (a).
An epoxy resin composition containing the component (c) within a range of 5 to 90 parts by weight with respect to a total of 100 parts by weight of the solid content in the components (a) and (c).

[In formula (1), X means a biphenylene skeleton represented by the following formula (2) or a naphthalene skeleton represented by the following formula (3), Y represents a biphenylene represented by the following formula (2) Z means a hydrogen atom or a glycidyl group, and n means a number representing a repeating unit. ]

[In Formula (2), R < ₁ > -R < ₈ > means a hydrogen atom or a C1-C4 linear or branched alkyl group each independently. ]   The epoxy resin composition according to claim 1, wherein the mesogenic group is a biphenylene group.   The epoxy resin composition according to claim 1, wherein the mesogenic group is a naphthalene group.   The epoxy resin composition according to claim 2, wherein the component (c) is an amorphous phenoxy resin in which X and Y in the formula (1) have a biphenylene skeleton represented by the formula (2). 5. In the formula (1), X is a biphenylene skeleton in which at least four of R _{1 to} R ₈ in the formula (2) are alkyl groups having 4 or less carbon atoms, and the rest are hydrogen atoms. The epoxy resin composition described in 1. The epoxy resin composition according to claim 5, wherein, in the formula (1), Y is an unsubstituted biphenylene skeleton in which all of R _{1 to} R ₈ in the formula (2) are hydrogen atoms.   In the formula (1), X is a tetraalkylbiphenylene group in which an alkyl group having 4 or less carbon atoms is substituted at the 3,3′-position and the 5,5′-position, and Y is an unsubstituted biphenylene group. Item 3. The epoxy resin composition according to Item 2.   The epoxy resin composition according to claim 3, wherein the component (c) is an amorphous phenoxy resin having a naphthalene skeleton represented by the formula (3) in the formula (1). In the formula (1), X is a naphthalene skeleton having a single bond at each of the 1-position and the 6-position, and Y is an unsubstituted group in which all of R _{1 to} R ₈ in the formula (2) are hydrogen atoms The epoxy resin composition according to claim 8, which is a biphenylene skeleton. In addition, the following ingredients (d),
(D) inorganic filler,
The epoxy resin composition according to any one of claims 1 to 9, comprising: In addition, the following ingredients (e),
(E) solvent,
The epoxy resin composition according to any one of claims 1 to 10, comprising:   The resin sheet formed by forming the epoxy resin composition of any one of Claims 1-11 in a film form.   The hardened | cured material formed by hardening | curing the epoxy resin composition of any one of Claims 1-11.   Phenoxy resin having a tetramethylbiphenylene group substituted with a methyl group at the 3,3′-position and the 5,5′-position and an unsubstituted biphenylene group and having a weight average molecular weight in the range of 10,000 to 200,000 .   The phenoxy resin according to claim 14, wherein the molar ratio of the tetramethylbiphenylene group substituted with a methyl group at the 3,3′-position and the 5,5′-position to the unsubstituted biphenylene group is about 1: 1.