WO2017209210A1

WO2017209210A1 - Epoxy resin composition, b-stage sheet, cured epoxy resin composition, resin sheet, metal foil with resin, and metallic substrate

Info

Publication number: WO2017209210A1
Application number: PCT/JP2017/020343
Authority: WO
Inventors: 一也木口; 慎吾田中; 智雄西山; 竹澤　由高
Original assignee: 日立化成株式会社
Priority date: 2016-06-02
Filing date: 2017-05-31
Publication date: 2017-12-07
Also published as: TW201815865A

Abstract

An epoxy resin composition which comprises two or more epoxy compounds each having a mesogen skeleton, a hardener, and an inorganic filler and in which the two or more epoxy compounds each having a mesogen skeleton are compatible with each other and can form a smectic structure upon reaction with the hardener.

Description

Epoxy resin composition, B stage sheet, cured epoxy resin composition, resin sheet, metal foil with resin, and metal substrate

The present invention relates to an epoxy resin composition, a B stage sheet, a cured epoxy resin composition, a resin sheet, a metal foil with resin, and a metal substrate.

In recent years, the amount of heat generation tends to increase with the miniaturization of electronic and electrical equipment, so how to dissipate that heat in an insulating material has become an important issue. As insulating materials used in these devices, thermosetting resin cured products are widely used from the viewpoints of insulation, heat resistance, and the like. However, since the heat conductivity of a thermosetting resin cured product is generally low and is a major factor that hinders heat dissipation, a thermosetting resin cured product having high thermal conductivity is desired.

As a thermosetting resin cured product having high thermal conductivity, a cured product of an epoxy resin composition having a mesogen skeleton in a molecular structure has been proposed (for example, see Patent Document 1). In addition, as a thermosetting resin having high thermal conductivity and a low softening point (melting point), biphenol is reacted with a mixed epoxy resin composed of glycidylated 4,4'-dihydroxybiphenylmethane and glycidylated biphenol. The modified epoxy resin obtained by this is proposed (for example, refer patent document 2).

Epoxy compounds with a mesogenic skeleton have a narrow temperature range for liquid crystals, and when they are cured and mixed at a temperature lower than the curing temperature, only those cured at a certain limited temperature range exhibit liquid crystallinity. It is known that it is difficult to easily obtain an epoxy resin cured product exhibiting the following. As a resin composition having a wide range of curing temperature when producing a cured resin and capable of easily producing a cured resin having high thermal conductivity, a plurality of epoxy compounds having a specific mesogen skeleton in the molecular structure are included. Resin compositions have been reported (see, for example, Patent Documents 3 and 4).
Furthermore, an insulating composition in which a liquid crystalline polymer and a thermosetting resin exist in a phase-separated state has been proposed (see, for example, Patent Document 5). In insulating compositions, it has been reported that liquid crystalline polymers are involved in high thermal conductivity, and thermosetting resins are involved in adhesion to metals such as copper.

Japanese Patent No. 4118691 JP 2007-332196 A JP 2008-239679 A JP 2008-266594 A JP 2010-18679 A

However, an epoxy resin having a mesogen skeleton in the molecular structure generally has a higher melting point as it has higher thermal conductivity, and there are cases where workability such as molding conditions becomes severe. In particular, when the epoxy resin has a high melting point, a high temperature is required for melting the epoxy resin, and thus the thermosetting temperature becomes high. When the temperature is increased for melting, the reaction rate between the epoxy resin and the curing agent increases. Therefore, the reaction with the curing agent is likely to be started before the high melting point epoxy resin is sufficiently melted. Therefore, the resin compositions of Patent Literature 3 and Patent Literature 4 have a high thermosetting temperature, and are cured before the orientation of the mesogen skeleton is aligned, so that the thermal conductivity inherent in the epoxy resin may not be sufficiently exhibited.
Further, the thermosetting resin of Patent Document 2 is not easy to synthesize, and development of a new epoxy resin that achieves both low melting point and improved thermal conductivity is desired.

According to the present invention, an epoxy resin composition capable of both lowering the melting point and improving the thermal conductivity after curing, and a B stage sheet, a cured epoxy resin composition, a resin sheet, and a resin using the epoxy resin composition Provided is a metal foil and a metal substrate.

The specific means for providing the above-mentioned problems include the following embodiments.

<1> Contains two or more epoxy compounds having a mesogenic skeleton, a curing agent, and an inorganic filler,
2 or more types of epoxy compounds which have the said mesogen skeleton are mutually compatible, The epoxy resin composition which can form a smectic structure by reacting with the said hardening | curing agent.

<2> The epoxy resin composition according to <1>, wherein the two or more epoxy compounds having the mesogenic skeleton include at least one compound represented by the following general formula (I).

In general formula (I), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

<3> The epoxy resin composition according to <1> or <2>, wherein the curing agent includes a phenol novolac resin.

<4> The curing agent includes a novolak resin having a structural unit represented by at least one selected from the group consisting of the following general formula (II-1) and the following general formula (II-2) <1> The epoxy resin composition according to any one of to <3>.

In general formula (II-1) and general formula (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group or an aralkyl group. R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represents an integer of 0-2. n21 and n22 each independently represents an integer of 1 to 7.

<5> The curing agent includes a novolak resin having a partial structure represented by at least one selected from the group consisting of the following general formula (III-1) to general formula (III-4) <1> The epoxy resin composition according to any one of to <3>.

In the general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ³¹ to Ar ³⁴ each independently represents any of the groups represented by the following general formula (III-a) or the following general formula (III-b).

In general formula (III-a) and general formula (III-b), R ³¹ and R ³⁴ each independently represents a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<6> The curing agent contains a monomer which is a phenol compound constituting the novolak resin, and the content of the monomer is 5% by mass to 80% by mass in the curing agent <1> to <5> The epoxy resin composition according to any one of the above.

<7> The epoxy resin according to any one of <1> to <6>, wherein the inorganic filler includes at least one selected from the group consisting of boron nitride, alumina, magnesium oxide, silica, and aluminum nitride. Composition.

<8> The epoxy resin composition according to any one of <1> to <7>, wherein the content of the inorganic filler exceeds 50% by volume in the solid content.

<9> A B stage sheet which is a sheet-like semi-cured product of the epoxy resin composition according to any one of <1> to <8>.

<10> A cured epoxy resin composition, which is a cured product of the epoxy resin composition according to any one of <1> to <8>.

<11> A resin sheet which is a sheet-like formed body of the epoxy resin composition according to any one of <1> to <8>.

<12> A resin foil comprising a metal foil and a semi-cured epoxy resin composition layer derived from the epoxy resin composition according to any one of <1> to <8> disposed on the metal foil. Metal foil.

<13> A metal support, a cured epoxy resin composition layer derived from the epoxy resin composition according to any one of <1> to <8> disposed on the metal support, and the cured epoxy A metal substrate comprising, in this order, a metal foil disposed on the resin composition layer.

According to the present invention, an epoxy resin composition capable of both lowering the melting point and improving the thermal conductivity after curing, and a B stage sheet, a cured epoxy resin composition, a resin sheet, and a resin using the epoxy resin composition An attached metal foil and a metal substrate can be provided.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.
In the present disclosure, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. .
In the present disclosure, numerical ranges indicated using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical description. . Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
In the present disclosure, each component may contain a plurality of corresponding substances. When multiple types of substances corresponding to each component are present in the composition, the content or content of each component is the total content or content of the multiple types of substances present in the composition unless otherwise specified. Means quantity.
In the present disclosure, a plurality of particles corresponding to each component may be included. When a plurality of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of particles present in the composition unless otherwise specified.
In the present disclosure, the term “layer” includes a case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. It is.
In the present disclosure, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.

The number of structural units indicates an integer value for a single molecule but a rational number that is an average value as an aggregate of a plurality of types of molecules.

A resin sheet obtained by further heating and pressing a resin sheet obtained by drying an epoxy resin composition layer formed from an epoxy resin composition may be referred to as a B stage sheet.
For the B stage, refer to the specifications in JIS K6900: 1994.

<Epoxy resin composition>
The epoxy resin composition of this embodiment contains two or more epoxy compounds having a mesogenic skeleton, a curing agent, and an inorganic filler, and the two or more epoxy compounds having the mesogenic skeleton are compatible with each other. It is possible to form a smectic structure by reacting with the curing agent.
With this configuration, the epoxy resin composition of the present embodiment can achieve both a low melting point and an improvement in thermal conductivity after curing. The reason is not clear, but is presumed as follows. The epoxy resin composition contains two or more kinds of epoxy compounds having a mesogen skeleton, and these are compatible with each other to form a smectic structure, thereby lowering the melting point of the epoxy resin composition before curing, and high heat after curing. It is thought that conductivity can be exhibited. The epoxy resin composition may further contain other components in addition to the above components.
Hereinafter, each component of the epoxy resin composition will be described in detail.

[Epoxy compound]
The epoxy resin composition contains two or more types of epoxy compounds having a mesogenic skeleton, and the epoxy compounds having a mesogenic skeleton are compatible with each other. The melting point of a mixture of epoxy compounds having two or more mesogenic skeletons compatible with each other (hereinafter also referred to as “epoxy mixture”) has the highest melting point among the epoxy compounds having a mesogenic skeleton constituting the epoxy mixture. There is a phenomenon in which the melting point is lower than the melting point of the epoxy compound having a mesogenic skeleton. Therefore, it becomes possible to exhibit the low melting point of the epoxy resin composition.
In addition, the thermal conductivity when the epoxy resin composition is made into a semi-cured product or a cured product is based on the thermal conductivity when the simple substance of an epoxy compound having a mesogen skeleton constituting the epoxy mixture is made into a semi-cured product or a cured product. Can also be increased.
When the epoxy mixture contains an epoxy compound having three or more kinds of mesogen skeletons, it is sufficient that the epoxy mixture composed of the epoxy compounds having all mesogen skeletons constituting the epoxy mixture is compatible as a whole. Any two kinds of epoxy compounds having a mesogenic skeleton selected from epoxy compounds having a skeleton may not be compatible with each other.
In the present disclosure, “two or more types of epoxy compounds” mean two or more types of epoxy compounds having different molecular structures. However, two or more types of epoxy compounds having a stereoisomer (optical isomer, geometric isomer, etc.) relationship do not fall under “two or more types of epoxy compounds” and are regarded as the same type of epoxy compound.
The epoxy compound according to the present embodiment may be an epoxy monomer or an epoxy resin, and is preferably an epoxy monomer from the viewpoint of higher-order structure formation (high thermal conductivity). The epoxy mixture may be a combination of an epoxy monomer and an epoxy monomer, a combination of an epoxy monomer and an epoxy resin, or a combination of an epoxy resin and an epoxy resin. From the viewpoint of formability of a higher order structure (high thermal conductivity). A combination of an epoxy monomer and an epoxy monomer is preferable.

In the present disclosure, the “mesogen skeleton” refers to a molecular structure that may exhibit liquid crystallinity. Specific examples include a biphenyl skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, a stilbene skeleton, and derivatives thereof. An epoxy resin composition containing an epoxy compound having a mesogenic skeleton tends to form a higher order structure upon curing, and tends to achieve higher thermal conductivity when a cured product is produced.

Here, the higher order structure is a state in which the constituent elements are arranged microscopically, and corresponds to, for example, a crystal phase and a liquid crystal phase. Whether or not such a higher-order structure exists can be easily determined by observation with a polarizing microscope. That is, when an interference pattern due to depolarization is observed in the observation in the crossed Nicol state, it can be determined that a higher order structure exists.
The higher order structure usually exists in an island shape in the resin, and forms a domain structure. Each island forming the domain structure is called a higher-order structure. The structural units constituting the higher order structure are generally bonded by a covalent bond.

High-order structures with high regularity derived from the mesogenic skeleton include nematic structures and smectic structures. The nematic structure is a liquid crystal structure in which the molecular long axis is oriented in a uniform direction and has only alignment order. On the other hand, the smectic structure is a liquid crystal structure having a one-dimensional positional order in addition to the orientation order and having a layer structure with a constant period. In addition, the direction of the period of the layer structure is uniform inside the structure having the same period of the smectic structure. That is, the order of molecules is higher in the smectic structure than in the nematic structure. When a highly ordered higher-order structure is formed in a semi-cured product or a cured product, it is possible to suppress scattering of phonons that are heat conductive media. For this reason, the smectic structure has a higher thermal conductivity than the nematic structure.
That is, the order of the molecule is higher in the smectic structure than in the nematic structure, and the thermal conductivity of the cured product is higher in the case of showing the smectic structure. Since the epoxy resin composition can form a smectic structure by reacting with a curing agent, it is considered that a high thermal conductivity can be exhibited.

Whether or not a smectic structure can be formed using the epoxy resin composition can be determined by the following method.
X-ray diffraction measurement is performed using an X-ray analyzer (for example, manufactured by Rigaku Corporation) using a CuK _α 1 line and a tube voltage of 40 kV, a tube current of 20 mA, and 2θ in the range of 0.5 ° to 30 °. When a diffraction peak exists in the range of 2θ of 1 ° to 10 °, it is determined that the periodic structure includes a smectic structure. Note that in the case of a highly ordered high-order structure derived from a mesogenic structure, a diffraction peak appears in the range of 2θ of 1 ° to 30 °.

In the present disclosure, “compatible” means that a phase separation state derived from an epoxy compound having a mesogen skeleton is not observed after the epoxy mixture is melted and naturally cooled, or each mesogen skeleton is included in the epoxy mixture. This means that even when the epoxy compound is phase-separated, the phase separation state is not observed when the epoxy resin composition is semi-cured or cured.

Whether or not epoxy compounds having a mesogenic skeleton are compatible with each other can be determined as follows. For example, the epoxy mixture is melted by heating above the temperature at which the epoxy mixture transitions to an isotropic phase, and then the molten epoxy mixture is allowed to cool naturally, and an optical microscope image (magnification: 100 times) is observed. It can be judged by observing whether or not the epoxy compound having each mesogenic skeleton contained is phase-separated. Moreover, it is set as an epoxy resin composition using this epoxy mixture, The temperature when forming a semi-hardened | cured material or hardened | cured material, ie, the optical microscope image (magnification of the semi-hardened material or hardened | cured material of an epoxy resin composition in hardening temperature. : 100 times), and it can be determined by observing whether or not the epoxy compound having each mesogen skeleton contained in the epoxy resin composition is phase-separated.

The curing temperature can be appropriately selected according to the epoxy resin composition. The curing temperature is preferably 100 ° C. or higher, more preferably 100 ° C. to 250 ° C., and still more preferably 120 ° C. to 210 ° C.

In addition to the above method, whether or not the epoxy compounds having a mesogenic skeleton are compatible with each other is to observe a semi-cured product or a cured product derived from the epoxy mixture using a scanning electron microscope (SEM). Can be examined. A cross section of a semi-cured product or a cured product derived from an epoxy mixture is cut with, for example, a diamond cutter, and then polished with abrasive paper and slurry, and the state of the cross section is, for example, 2000 times magnification using an SEM. Observe at. In the case of a semi-cured product or a cured product derived from an epoxy mixture comprising a combination of epoxy compounds that undergo phase separation, the state of phase separation can be clearly observed.

In addition, the melting point of an epoxy mixture comprising an epoxy compound having a compatible mesogenic skeleton is higher than the melting point of an epoxy compound having a mesogenic skeleton having the highest melting point among the epoxy compounds having a mesogenic skeleton constituting the epoxy mixture. The phenomenon that becomes lower is also seen. The melting point here refers to a temperature at which an epoxy compound undergoes a phase transition from a liquid crystal phase to an isotropic phase in an epoxy compound having a liquid crystal phase. In the case of an epoxy compound that does not have a liquid crystal phase, it indicates the temperature at which the substance changes its state from a solid (crystalline phase) to a liquid (isotropic phase).
The liquid crystal phase is one of the phases located between the crystalline state (crystalline phase) and the liquid state (isotropic phase). Although the molecular orientation direction maintains some order, it is in a three-dimensional position. It refers to the state that lost order.

The presence or absence of a liquid crystal phase can be determined by a method of observing a change in the state of a substance in the process of raising the temperature from room temperature (for example, 25 ° C.) using a polarizing microscope. In the observation in the crossed Nicols state, interference fringes due to depolarization are seen in the crystal phase and the liquid crystal phase, and the isotropic phase appears in the dark field. The transition from the crystal phase to the liquid crystal phase can be confirmed by the presence or absence of fluidity. In other words, the expression of the liquid crystal phase means that the liquid crystal phase has a fluidity and has a temperature region where interference fringes due to depolarization are observed.
That is, if it is confirmed that the epoxy compound or the epoxy mixture having a mesogenic skeleton has fluidity and has a temperature range in which interference fringes due to depolarization are observed in observation in a crossed Nicol state, It is judged that the epoxy compound or epoxy mixture having a skeleton has a liquid crystal phase.

The width of the temperature region in which the epoxy mixture exhibits a liquid crystal phase is preferably 10 ° C or higher, more preferably 20 ° C or higher, and further preferably 40 ° C or higher. When the temperature region is 10 ° C. or higher, high thermal conductivity of the cured product tends to be achieved. Furthermore, the wider the temperature region, the easier it is to obtain a cured product having a higher thermal conductivity, which is preferable.

The melting point of the epoxy compound or epoxy mixture having a mesogenic skeleton is differentially measured using a differential scanning calorimeter (DSC) in the temperature range of 25 ° C. to 350 ° C. under the condition of a temperature increase rate of 10 ° C./min. Scanning calorimetry is performed and measured as the temperature at which an energy change (endothermic reaction) occurs with the phase transition. From the viewpoint of workability and reactivity, the melting point of the epoxy compound or epoxy mixture having a mesogenic skeleton is preferably 120 ° C. or lower.

When the epoxy compounds having a mesogenic skeleton are compatible with each other, that is, in a semi-cured product or a cured product derived from an epoxy mixture, the epoxy compounds having a mesogenic skeleton are not in phase separation from each other. Even in the case where an epoxy resin composition is formed by adding a curing agent, an inorganic filler, etc. to an epoxy compound having epoxide, the epoxy compounds having a mesogen skeleton are phase-separated from each other in the semi-cured or cured product of the epoxy resin composition. There is a tendency to be in a state without.

Two or more types of epoxy compounds having a mesogen skeleton contained in the epoxy resin composition are compatible with each other and are not particularly limited as long as they can form a smectic structure by reacting with a curing agent described later. It can be suitably selected from epoxy compounds having a mesogenic skeleton.
Examples of such an epoxy compound having a mesogenic skeleton include an epoxy compound having a mesogenic skeleton and two glycidyl groups in one molecule.

Examples of the epoxy compound having a mesogenic skeleton and having two glycidyl groups in one molecule include a biphenyl type epoxy compound and a tricyclic type epoxy compound.

Biphenyl type epoxy compounds include 4,4′-bis (2,3-epoxypropoxy) biphenyl or 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethyl. Examples include epoxy compounds mainly composed of biphenyl, and epoxy compounds obtained by reacting epichlorohydrin with 4,4′-biphenol or 4,4 ′-(3,3 ′, 5,5′-tetramethyl) biphenol. It is done.

Examples of the tricyclic epoxy compounds include epoxy compounds having a terphenyl skeleton, 1- (3-methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1- (3-Methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -benzene, 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2, 3-epoxypropoxy) benzoate and the like.

From the viewpoint of achieving higher thermal conductivity, an epoxy compound having a mesogenic skeleton and having two glycidyl groups in one molecule is high when cured as an epoxy compound alone. It is preferable that the following structure can be formed, and it is more preferable that a smectic structure can be formed. Examples of such an epoxy compound include a compound represented by the following general formula (I) (hereinafter also referred to as “specific epoxy compound”). When an epoxy resin composition contains a specific epoxy compound, it becomes possible to achieve a higher thermal conductivity.

In general formula (I), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹ to R ⁴ are each independently preferably a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. In addition, 2 to ⁴ of R ¹ to R ⁴ are preferably hydrogen atoms, more preferably 3 or 4 are hydrogen atoms, and all 4 are further hydrogen atoms. preferable. When any of R ¹ to R ⁴ is an alkyl group having 1 to 3 carbon atoms, at least one of R ¹ and R ⁴ is preferably an alkyl group having 1 to 3 carbon atoms.

A preferable example of the specific epoxy compound is described in, for example, JP-A-2011-74366. Specifically, specific epoxy compounds include 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate and 4- {4- (2,3-epoxy Propoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) -3-methylbenzoate is preferred at least one compound selected from the group consisting of.

From the viewpoint of high thermal conductivity, the two or more epoxy compounds having a mesogenic skeleton preferably include at least one specific epoxy compound, more preferably include two or more specific epoxy compounds, and constitute an epoxy mixture. It is particularly preferable that all epoxy compounds having a mesogenic skeleton are specific epoxy compounds.

From the viewpoint of lowering the melting point and thermal conductivity, the epoxy resin composition is different from the specific epoxy compound in addition to the specific epoxy compound and has an mesogenic skeleton that is compatible with the specific epoxy compound (hereinafter, “ It may also be referred to as “another epoxy compound having a mesogenic skeleton”.
As another epoxy compound having a mesogenic skeleton, it is preferable that a nematic structure can be formed when cured by using one epoxy compound alone. Examples of such an epoxy compound include a biphenyl type epoxy compound. From the viewpoint of material availability, cost, and thermal conductivity, a biphenyl type epoxy compound is preferable.

Examples of the biphenyl type epoxy compound include 4,4′-bis (2,3-epoxypropoxy) biphenyl.
As the biphenyl type epoxy compound, product names such as “YX4000”, “YL6121H” (Mitsubishi Chemical Corporation), “NC-3000”, “NC-3100” (Nippon Kayaku Co., Ltd.) And those commercially available.
Among those commercially available, “YL6121H” (manufactured by Mitsubishi Chemical Corporation) is more preferable from the viewpoint of lowering the melting point and improving the thermal conductivity. Other epoxy compounds having a mesogenic skeleton may be used alone or in combination of two or more.

When the epoxy mixture contains a specific epoxy compound and another epoxy compound having a mesogen skeleton, the mixing ratio of the specific epoxy compound and another epoxy compound having a mesogen skeleton is low melting point and heat conduction From the standpoint of improving efficiency, the epoxy equivalent number ratio is preferably in the range of 5: 5 to 9.5: 0.5 (specific epoxy compound: other epoxy compound having a mesogenic skeleton), A range of 6: 4 to 9: 1 is more preferable, and a range of 7: 3 to 9: 1 is still more preferable.

As long as the epoxy resin composition can form a smectic structure by the reaction of the epoxy mixture and the curing agent described later, the epoxy resin composition is further referred to as another epoxy compound having no mesogenic skeleton (hereinafter referred to as “non-mesogenic epoxy compound”). .) May be included. Examples of non-mesogenic epoxy compounds include bisphenol type epoxy compounds and triphenylmethane type epoxy compounds. From the viewpoint of availability and cost, a bisphenol-type epoxy compound is preferable.

Examples of the bisphenol type epoxy compound include a bisphenol A type epoxy compound and a bisphenol F type epoxy compound.
The bisphenol type epoxy compound is commercially available under the product names such as “ZX1059”, “VSLV-80XY” (manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.), “828EL” (manufactured by Mitsubishi Chemical Corporation), etc. Is mentioned.
The triphenylmethane type epoxy compound is not particularly limited as long as it is an epoxy compound made from a compound having a triphenylmethane skeleton, and “1032H60” (Mitsubishi Chemical Corporation), “EPPN-502H” (Nipponization) And those marketed under product names such as Yakuhin Co., Ltd.).

The content of the non-mesogenic epoxy compound in the epoxy mixture is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and 1% by mass or less. It is particularly preferred.

The content of the specific epoxy compound in the epoxy mixture is not particularly limited as long as it can form a smectic structure by the reaction of the epoxy mixture and the curing agent described later, and can be appropriately selected. From the viewpoint of lowering the melting point, the content of the epoxy compound having a mesogen skeleton is preferably 5% by mass or more, more preferably 10% by mass to 100% by mass with respect to the total mass of the epoxy mixture, More preferably, it is 100 mass%.

The total content of the epoxy compound having a mesogen skeleton in the epoxy resin composition is not particularly limited. From the viewpoint of thermosetting and thermal conductivity, the total content of the epoxy compound having a mesogenic skeleton is preferably 3% by mass to 10% by mass with respect to the total mass of the epoxy resin composition, and 5% by mass to More preferably, it is 10 mass%.

[Curing agent]
The epoxy resin composition contains a curing agent. The curing agent is not particularly limited as long as it is a compound capable of undergoing a curing reaction with an epoxy compound having a mesogenic skeleton, and a commonly used curing agent can be appropriately selected and used. Specific examples of the curing agent include acid anhydride curing agents, amine curing agents, phenol curing agents, polyaddition curing agents such as mercaptan curing agents, and catalytic curing agents such as imidazole. These curing agents may be used alone or in combination of two or more.
Among these, from the viewpoint of heat resistance, it is preferable to use at least one selected from the group consisting of amine-based curing agents and phenol-based curing agents, and from the viewpoint of storage stability, phenol-based curing agents. More preferably, at least one of the above is used.

As the amine curing agent, those usually used as a curing agent for epoxy compounds can be used without particular limitation, and commercially available ones may be used. Among these, from the viewpoint of curability, the amine curing agent is preferably a polyfunctional curing agent having two or more functional groups, and from the viewpoint of thermal conductivity, is a polyfunctional curing agent having a rigid skeleton. It is more preferable.

Specific examples of the bifunctional amine curing agent include 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 4,4′-diamino-3,3. Examples include '-dimethoxybiphenyl, 4,4'-diaminophenyl benzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,4-diaminonaphthalene, 1,8-diaminonaphthalene and the like.
Among these, from the viewpoint of thermal conductivity, at least one selected from the group consisting of 4,4′-diaminodiphenylmethane and 1,5-diaminonaphthalene is preferable, and 1,5-diaminonaphthalene is more preferable. preferable.

As a phenol type hardening | curing agent, what is normally used as a hardening | curing agent of an epoxy compound can be especially used without a restriction | limiting, You may use what is marketed. For example, phenol and a novolac phenol resin can be used.
Examples of phenolic curing agents include monofunctional compounds such as phenol, o-cresol, m-cresol, and p-cresol; bifunctional compounds such as catechol, resorcinol, and hydroquinone; 1,2,3-trihydroxybenzene, 1 , 2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene and the like trifunctional compounds. As the curing agent, a phenol novolac resin obtained by connecting these phenolic curing agents with a methylene chain or the like to form a novolak can be used.

Specific examples of the phenol novolak resin include resins obtained by novolacizing one phenol compound such as cresol novolak resin, catechol novolak resin, resorcinol novolak resin, hydroquinone novolak resin; catechol resorcinol novolak resin, resorcinol hydroquinone novolak resin, etc. Examples thereof include resins obtained by novolacizing two or more phenol compounds.

When a phenol novolac resin is used as the phenolic curing agent, the phenol novolak resin has a structural unit represented by at least one selected from the group consisting of the following general formulas (II-1) and (II-2) It is preferable to include a novolac resin.

The alkyl group may be linear, branched or cyclic.
The aryl group may have a structure containing a hetero atom in the aromatic ring. In this case, a heteroaryl group in which the total number of heteroatoms and carbon is 6 to 12 is preferable.
The alkylene group in the aralkyl group may be any of a chain, a branched chain, and a cyclic group. The aryl group in the aralkyl group may have a structure containing a hetero atom in the aromatic ring. In this case, a heteroaryl group in which the total number of heteroatoms and carbon is 6 to 12 is preferable.

In general formula (II-1) and general formula (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. These alkyl group, aryl group, and aralkyl group may further have a substituent. Examples of the substituent include an alkyl group (except when R ²¹ and R ²⁴ are alkyl groups), an aromatic group, a halogen atom, and a hydroxyl group.
m21 and m22 each independently represents an integer of 0 to 2, and when m21 or m22 is 2, two R ²¹ or R ²⁴ may be the same or different. m21 and m22 are each independently preferably 0 or 1, and more preferably 0.
n21 and n22 are the number of structural units represented by the general formulas (II-1) and (II-2) contained in the phenol novolac resin, and each independently represents an integer of 1 to 7.

In general formula (II-1) and general formula (II-2), R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group and aralkyl group represented by R ²² , R ²³ , R ²⁵ and R ²⁶ may further have a substituent. Examples of the substituent include an alkyl group (provided that R ²² , R ²³ , R ²⁵ and R ²⁶ are alkyl groups), an aryl group, a halogen atom, a hydroxyl group and the like.

In formulas (II-1) and (II-2), R ²² , R ²³ , R ²⁵ and R ²⁶ are each independently a hydrogen atom, an alkyl group, from the viewpoint of storage stability and thermal conductivity, Alternatively, it is preferably an aryl group, more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and further preferably a hydrogen atom.
Furthermore, from the viewpoint of heat resistance, at least one of R ²² and R ²³ is preferably an aryl group, more preferably an aryl group having 6 to 12 carbon atoms. Similarly, at least one of R ²⁵ and R ²⁶ is preferably an aryl group, and more preferably an aryl group having 6 to 12 carbon atoms.
The aryl group may have a structure containing a hetero atom in the aromatic ring. In this case, a heteroaryl group in which the total number of heteroatoms and carbon is 6 to 12 is preferable.

The phenolic curing agent may contain one type of compound having the structural unit represented by the general formula (II-1) or the general formula (II-2), or may contain two or more types. Preferably, it contains at least one compound having a structural unit derived from resorcinol represented by the general formula (II-1).

The compound having the structural unit represented by the general formula (II-1) may further include at least one partial structure derived from a phenol compound other than resorcinol. In the general formula (II-1), examples of the partial structure derived from a phenol compound other than resorcinol include phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxy. Examples thereof include partial structures derived from benzene and 1,3,5-trihydroxybenzene. The partial structures derived from these may be contained singly or in combination of two or more.
Further, the compound having the structural unit represented by the general formula (II-2) may contain at least one partial structure derived from a phenol compound other than catechol. In the general formula (II-2), examples of the partial structure derived from a phenol compound other than catechol include, for example, phenol, cresol, resorcinol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxy Examples thereof include partial structures derived from benzene and 1,3,5-trihydroxybenzene. The partial structures derived from these may be contained singly or in combination of two or more.

Here, the partial structure derived from the phenol compound means a monovalent or divalent group constituted by removing one or two hydrogen atoms from the benzene ring portion of the phenol compound. The position where the hydrogen atom is removed is not particularly limited.

In the compound having the structural unit represented by the general formula (II-1), the content of the partial structure derived from resorcinol is not particularly limited. From the viewpoint of the elastic modulus, the content of the partial structure derived from resorcinol is preferably 55% by mass or more based on the total mass of the compound having the structural unit represented by the general formula (II-1), and the glass transition temperature ( From the viewpoint of Tg) and the linear expansion coefficient, it is more preferably 80% by mass or more, and further preferably 90% by mass or more from the viewpoint of thermal conductivity.

Furthermore, the phenol novolac resin preferably includes a novolak resin having a partial structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4).

In the general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer and represent the number of each structural unit contained. Ar ³¹ to Ar ³⁴ each independently represents any of the groups represented by the following general formula (III-a) or the following general formula (III-b).

In general formula (III-a) and general formula (III-b), R ³¹ and R ³⁴ each independently represents a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

A curing agent having a partial structure represented by at least one of general formula (III-1) to general formula (III-4) is produced as a by-product by a production method described later in which a divalent phenol compound is novolaked. It can be generated.

The partial structures represented by the general formulas (III-1) to (III-4) may be included as the main chain skeleton of the compound or may be included as a part of the side chain. Furthermore, each structural unit constituting the partial structure represented by any one of the general formulas (III-1) to (III-4) may be included randomly or regularly. It may be included or may be included in a block shape. Further, in the general formulas (III-1) to (III-4), the substitution position of the hydroxyl group is not particularly limited as long as it is on the aromatic ring.

For each of the general formulas (III-1) to (III-4), a plurality of Ar ³¹ to Ar ³⁴ may all be the same atomic group or contain two or more atomic groups. Also good. Ar ³¹ to Ar ³⁴ each independently represent a group represented by any one of general formula (III-a) and general formula (III-b).

R ³¹ and R ³⁴ in formulas (III-a) and (III-b) are each independently a hydrogen atom or a hydroxyl group, but are preferably a hydroxyl group from the viewpoint of thermal conductivity. Further, the substitution positions of R ³¹ and R ³⁴ are not particularly limited.

R ³² and R ³³ in general formula (III-a) and general formula (III-b) each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms in R ³² and R ³³ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, hexyl. Groups, heptyl groups, and octyl groups. In addition, the substitution positions of R ³² and R ³³ in general formula (III-a) and general formula (III-b) are not particularly limited.

Ar ³¹ to Ar ³⁴ in the general formula (III-a) and the general formula (III-b) are groups derived from dihydroxybenzene (in the general formula (III-a), from the viewpoint of achieving higher thermal conductivity. A group in which R ³¹ is a hydroxyl group and R ³² and R ³³ are hydrogen atoms) and a group derived from dihydroxynaphthalene (a group in which R ³⁴ is a hydroxyl group in formula (III-b)). One type is preferable.

Here, the “group derived from dihydroxybenzene” means a divalent group formed by removing two hydrogen atoms from the aromatic ring portion of dihydroxybenzene, and the position at which the hydrogen atom is removed is not particularly limited. Further, the “group derived from dihydroxynaphthalene” has the same meaning.

Further, from the viewpoint of productivity and fluidity of the epoxy resin composition, Ar ³¹ to Ar ³⁴ are more preferably each independently a group derived from dihydroxybenzene, and 1,2-dihydroxybenzene (catechol) More preferably, it is at least one selected from the group consisting of a group derived from the above and a group derived from 1,3-dihydroxybenzene (resorcinol). In particular, Ar ³¹ to Ar ³⁴ preferably include at least a group derived from resorcinol from the viewpoint of particularly improving thermal conductivity. Further, from the viewpoint of particularly improving thermal conductivity, the structural unit represented by n31 to n34 preferably contains a group derived from resorcinol.

When the compound having a partial structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) includes a structural unit derived from resorcinol, it is derived from resorcinol The content of the structural unit containing a group is 55% by mass in the whole compound having a structure represented by at least one of general formulas (III-1) to (III-4) from the viewpoint of elastic modulus. % From the viewpoint of Tg and linear expansion coefficient, more preferably 80% by mass or more, and further preferably 90% by mass or more from the viewpoint of thermal conductivity.

In the general formulas (III-1) to (III-4), the ratio of mx and nx (x is the same value of any one of 31, 32, 33, or 34) is mx / nx from the viewpoint of fluidity. = 20/1 to 1/5 is preferable, 20/1 to 5/1 is more preferable, and 20/1 to 10/1 is still more preferable. Further, the total value of mx and nx is preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less from the viewpoint of fluidity. In addition, the lower limit of the total value of m and n is not particularly limited.

Mx and nx represent the number of structural units and indicate how much the corresponding structural unit is added in the molecule. Therefore, an integer value is shown for a single molecule. Note that mx and nx in (mx / nx) and (mx + nx) indicate rational numbers that are average values in the case of an assembly of a plurality of types of molecules.

Phenol novolac resins having a partial structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) are particularly those in which Ar ³¹ to Ar ³⁴ are substituted or unsubstituted. In the case of at least one of dihydroxybenzene and substituted or unsubstituted dihydroxynaphthalene, the synthesis is easy and a curing agent having a low melting point can be obtained as compared with a novolak phenol resin or the like. There is a tendency. Therefore, by including such a phenol resin as a curing agent, there are advantages such as easy manufacture and handling of the epoxy resin composition.
Whether or not the phenol novolac resin has a partial structure represented by any of the general formulas (III-1) to (III-4) is determined by field desorption ionization mass spectrometry (FD-MS). The fragment component can be determined by whether or not a component corresponding to the partial structure represented by any one of the general formulas (III-1) to (III-4) is included.

The molecular weight of the phenol novolac resin having a partial structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is not particularly limited. From the viewpoint of fluidity, the number average molecular weight (Mn) is preferably 2000 or less, more preferably 1500 or less, and even more preferably 350 to 1500. Further, the weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and further preferably 400 to 1500. Mn and Mw are measured by a usual method using GPC (gel permeation chromatography).

The hydroxyl equivalent of the phenol novolac resin having a partial structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is not particularly limited. From the viewpoint of the crosslinking density involved in the heat resistance, the hydroxyl group equivalent is preferably 50 g / eq to 150 g / eq on average, more preferably 50 g / eq to 120 g / eq, and 55 g / eq to 120 g / eq. More preferably, it is eq. In the present disclosure, the hydroxyl equivalent refers to a value measured in accordance with JIS K0070: 1992.

The phenol novolac resin may contain a monomer that is a phenol compound constituting the phenol novolac resin. The content of the monomer that is a phenol compound constituting the phenol novolac resin (hereinafter also referred to as “monomer content”) is not particularly limited. From the viewpoint of thermal conductivity and moldability, the monomer content in the cured product is preferably 5% by mass to 80% by mass, more preferably 15% by mass to 60% by mass, and more preferably 20% by mass to More preferably, it is 50 mass%.

When the monomer content is 80% by mass or less, the amount of monomers that do not contribute to crosslinking decreases during the curing reaction, and the high molecular weight material that contributes to crosslinking occupies a large amount. It is formed and the thermal conductivity tends to be improved. In addition, since the monomer content is 5% by mass or more, since it is easy to flow during molding, the adhesion with the inorganic filler is further improved, and more excellent thermal conductivity and heat resistance tend to be achieved. It is in.

The content of the curing agent in the epoxy resin composition is not particularly limited. For example, when the curing agent is an amine curing agent, the ratio of the number of active hydrogen equivalents of the amine curing agent (equivalent number of amine groups) to the number of epoxy group equivalents of the epoxy compound (equivalent number of amine groups / The number of equivalents of epoxy groups is preferably 0.5 to 2.0, and more preferably 0.8 to 1.2. When the curing agent is a phenolic curing agent, the ratio of the number of equivalents of the phenolic hydroxyl group of the phenolic curing agent (the number of equivalents of the phenolic hydroxyl group) to the number of equivalents of the epoxy group of the epoxy compound (of the phenolic hydroxyl group) (Equivalent number / Equivalent number of epoxy group) is preferably 0.5 to 2.0, and more preferably 0.8 to 1.2.

(Curing accelerator)
When using a phenol type hardening | curing agent in an epoxy resin composition, you may use a hardening accelerator together as needed. By using a curing accelerator in combination, it can be further sufficiently cured. The kind and content of the curing accelerator are not particularly limited, and an appropriate one can be selected from the viewpoint of reaction rate, reaction temperature, and storage property.

Specific examples include imidazole compounds, tertiary amine compounds, organic phosphine compounds, complexes of organic phosphine compounds and organic boron compounds, and the like. Among these, from the viewpoint of heat resistance, it is preferably at least one selected from the group consisting of an organic phosphine compound and a complex of an organic phosphine compound and an organic boron compound.

Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl (p-tolyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, and tris (dialkylphenyl). ) Phosphine, tris (trialkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkylphosphine, dialkylarylphosphine And alkyldiarylphosphine.

Specific examples of the complex of an organic phosphine compound and an organic boron compound include tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / tetra-p-tolylborate, tetrabutylphosphonium / tetraphenylborate, and tetraphenylphosphonium. -N-butyltriphenylborate, butyltriphenylphosphonium / tetraphenylborate, methyltributylphosphonium / tetraphenylborate and the like.
One of these curing accelerators may be used alone, or two or more thereof may be used in combination.

When using two or more types of curing accelerators in combination, the mixing ratio should be determined without any particular restrictions depending on the characteristics (for example, how much flexibility is required) required for the semi-cured epoxy resin composition. Can do.

When the epoxy resin composition contains a curing accelerator, the content of the curing accelerator in the epoxy resin composition is not particularly limited. From the viewpoint of moldability, the content of the curing accelerator is preferably 0.5% by mass to 1.5% by mass of the total mass of the epoxy compound and the curing agent, and 0.5% by mass to 1% by mass. More preferably, the content is 0.6% by mass to 1% by mass.

(Inorganic filler)
The epoxy resin composition contains at least one inorganic filler. By including the inorganic filler, the epoxy resin composition can achieve high thermal conductivity.
The inorganic filler may be non-conductive or conductive. By using a non-conductive inorganic filler, the risk of lowering the insulation tends to be reduced. Moreover, it exists in the tendency for thermal conductivity to improve more by using a conductive inorganic filler.

Specific examples of the non-conductive inorganic filler include aluminum oxide (alumina), magnesium oxide, aluminum nitride, boron nitride, silicon nitride, silica (silicon oxide), aluminum hydroxide, and barium sulfate. Examples of the conductive inorganic filler include gold, silver, nickel, and copper. Among these, from the viewpoint of thermal conductivity, the inorganic filler is preferably at least one selected from the group consisting of aluminum oxide (alumina), boron nitride, magnesium oxide, aluminum nitride, and silica (silicon oxide). More preferably, it is at least one selected from the group consisting of boron nitride and aluminum oxide (alumina).
These inorganic fillers may be used alone or in combination of two or more.

It is preferable to use a mixture of two or more inorganic fillers having different volume average particle diameters. As a result, the inorganic filler having a small particle diameter is packed in the voids of the inorganic filler having a large particle diameter, thereby filling the inorganic filler more densely than using only the inorganic filler having a single particle diameter. It becomes possible to exhibit higher thermal conductivity.
Specifically, when aluminum oxide is used as the inorganic filler, aluminum oxide having a volume average particle diameter of 16 μm to 20 μm is oxidized in the inorganic filler by 60 volume% to 75 volume% and volume average particle diameter of 2 μm to 4 μm. By mixing aluminum oxide having a volume average particle size of 0.3 μm to 0.5 μm in a ratio of 10 vol% to 20 vol%, it is possible to achieve closer packing. Become.
Further, when boron nitride and aluminum oxide are used in combination as the inorganic filler, boron nitride having a volume average particle diameter of 20 μm to 100 μm in the inorganic filler is oxidized by 60 volume% to 90 volume% and volume average particle diameter of 2 μm to 4 μm. Higher thermal conductivity can be achieved by mixing aluminum oxide having a volume average particle size of 0.3 μm to 0.5 μm in a range of 5% by volume to 20% by volume with 5% to 20% by volume of aluminum. . The volume average particle diameter of the inorganic filler is measured under normal conditions using a laser diffraction particle size distribution measuring apparatus.

The volume average particle diameter (D50) of the inorganic filler can be measured using a laser diffraction method. For example, the inorganic filler in the epoxy resin composition is extracted and measured using a laser diffraction / scattering particle size distribution analyzer (for example, trade name: LS230, manufactured by Beckman Coulter, Inc.). Specifically, using an organic solvent, nitric acid, aqua regia, etc., the inorganic filler component is extracted from the epoxy resin composition and sufficiently dispersed with an ultrasonic disperser, etc., and the weight cumulative particle size distribution curve of this dispersion liquid Measure.
The volume average particle diameter (D50) refers to the particle diameter at which accumulation is 50% from the small diameter side in the volume cumulative distribution curve obtained from the above measurement.

The content of the inorganic filler in the epoxy resin composition is not particularly limited. Among them, from the viewpoint of thermal conductivity, the content of the inorganic filler is preferably more than 50% by volume, more than 70% by volume, more than 70% by volume, with respect to 100% by volume of the total solid content of the epoxy resin composition. More preferably, it is not more than volume%.
When the content of the inorganic filler exceeds 50% by volume, higher thermal conductivity can be achieved. On the other hand, when the content of the inorganic filler is 90% by volume or less, the flexibility of the epoxy resin composition and the insulating property tend to be suppressed.

(Silane coupling agent)
The epoxy resin composition may contain at least one silane coupling agent. The silane coupling agent has a role of forming a covalent bond between the surface of the inorganic filler and the surrounding resin (equivalent to a binder agent), an improvement in thermal conductivity, and prevents moisture penetration. It is considered possible to improve the performance.

The type of silane coupling agent is not particularly limited, and a commercially available product may be used. In consideration of reducing the compatibility between the epoxy compound having a mesogenic skeleton and the curing agent, and reducing heat conduction defects at the interface between the resin layer and the inorganic filler, in this embodiment, the terminal is an epoxy group, an amino group. It is preferable to use a silane coupling agent having a mercapto group, a ureido group and a hydroxyl group.

Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane. 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxy Examples thereof include silane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-ureidopropyltriethoxysilane. Also included are silane coupling agent oligomers (manufactured by Hitachi Chemical Techno Service Co., Ltd.) represented by trade name: SC-6000KS2. These silane coupling agents may be used alone or in combination of two or more.

(Other ingredients)
The epoxy resin composition may contain other components in addition to the above components, if necessary. Examples of other components include a solvent, an elastomer, a dispersant, and an anti-settling agent.
The solvent is not particularly limited as long as it does not inhibit the curing reaction of the epoxy resin composition, and a commonly used organic solvent can be appropriately selected and used.

[Resin sheet]
The resin sheet of this embodiment is a sheet-like formed body of an epoxy resin composition. The resin sheet is provided on a support with a varnish-like epoxy resin composition (hereinafter also referred to as “resin varnish”) prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition. After the resin layer (epoxy resin composition layer) is formed, it can be produced by removing at least part of the organic solvent from the resin layer by drying. Examples of the support include a release film such as a PET (polyethylene terephthalate) film.

The application of the resin varnish can be performed by a known method. Specifically, it can be performed by a method such as comma coating, die coating, lip coating, or gravure coating. Examples of a method for forming an epoxy resin composition layer having a predetermined thickness include a comma coating method in which an object to be coated is passed between gaps, and a die coating method in which a resin varnish whose flow rate is adjusted from a nozzle is applied. For example, when the thickness of the resin layer (epoxy resin composition layer) before drying is 50 μm to 500 μm, it is preferable to use a comma coating method.

The drying method is not particularly limited as long as at least a part of the organic solvent contained in the resin varnish can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the resin varnish. In general, a heat treatment method at about 80 ° C. to 150 ° C. can be mentioned.

The density of the resin sheet is not particularly limited, for ^example, be a 3g / cm 2 ~ 3.4g / cm 2. In consideration of the compatibility between the flexibility and the thermal conductivity of the resin sheet, 3 g / cm ² to 3.3 g / cm ² is preferable, and 3.1 g / cm ² to 3.3 g / cm ² is more preferable.
The density of the resin sheet can be adjusted by, for example, the inorganic filler content.

The thickness of the resin sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness of the resin sheet can be 50 μm to 350 μm, and is preferably 60 μm to 300 μm from the viewpoints of thermal conductivity, electrical insulation, and sheet flexibility.

Resin sheet (epoxy resin composition layer) hardly undergoes curing reaction. For this reason, although it has flexibility, its flexibility as a sheet is poor. Therefore, in a state where a support such as a PET film is removed, the sheet self-supporting property is poor and handling may be difficult. Therefore, the resin sheet is preferably one obtained by semi-curing an epoxy resin composition constituting the resin sheet. The resin sheet is preferably a B stage sheet that is further heat-treated until the epoxy resin composition layer is in a semi-cured state (B stage state).

[B stage sheet]
The B stage sheet of this embodiment is a sheet-like semi-cured product of an epoxy resin composition.
The B stage sheet can be manufactured, for example, by a manufacturing method including a step of heat-treating the resin sheet to the B stage state. By forming the resin sheet by heat treatment, it is excellent in thermal conductivity and electrical insulation, and excellent in flexibility and pot life as a B stage sheet.
The B stage sheet of this embodiment is an epoxy having a viscosity of 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 ° C.) and 10 ² Pa · s to 10 ³ Pa · s at 100 ° C. It means a resin sheet formed from a resin composition. Further, the cured epoxy resin composition layer is not melted by heating. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min).

The conditions for heat-treating the resin sheet are not particularly limited as long as the epoxy resin composition layer can be semi-cured to the B stage state, and can be appropriately selected according to the configuration of the epoxy resin composition. The heat treatment is preferably performed by a method selected from hot vacuum press, hot roll laminating and the like for the purpose of reducing voids in the resin layer generated when the resin varnish is applied. Thereby, the B stage sheet | seat with a flat surface can be manufactured efficiently.
Specifically, for example, the epoxy resin composition is heated and pressurized under reduced pressure (for example, 1 kPa) at a temperature of 80 ° C. to 130 ° C. for 1 second to 30 seconds and a press pressure of 1 MPa to 30 MPa. It can be semi-cured to the B stage state.

The thickness of the B stage sheet can be appropriately selected according to the purpose. For example, the thickness may be 50 μm to 350 μm, and is preferably 60 μm to 300 μm from the viewpoints of thermal conductivity, electrical insulation, and flexibility. Moreover, the resin sheet which has an epoxy resin composition layer can also be produced by heat-pressing, laminating | stacking two or more resin sheets.

<Semi-cured epoxy resin composition>
The semi-cured epoxy resin composition of the present embodiment is a semi-cured product of the epoxy resin composition. The semi-cured epoxy resin composition is derived from the epoxy resin composition, and is obtained by semi-curing the epoxy resin composition.

The semi-cured epoxy resin composition of the present embodiment is a semi-cured product of an epoxy resin composition in which the resin component melts when heated to 80 ° C. to 120 ° C. and the viscosity decreases to 10 Pa · s to 10 ⁴ Pa · s. means. Further, in the cured epoxy resin composition described later, the resin component does not melt by heating. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min).
The semi-curing treatment can be performed, for example, by a method of heating the epoxy resin composition at a temperature of 50 ° C. to 180 ° C. for 1 minute to 30 minutes.

[Curing epoxy resin composition]
The cured epoxy resin composition of the present embodiment is a cured product of the epoxy resin composition. The cured epoxy resin composition of the present embodiment is derived from the epoxy resin composition, and is obtained by curing the epoxy resin composition. The cured epoxy resin composition of this embodiment is excellent in thermal conductivity, which can be considered, for example, because an epoxy compound having a mesogenic group in the molecule contained in the epoxy resin composition forms a smectic structure. .

The cured epoxy resin composition can be obtained by curing an uncured epoxy resin composition or a semi-cured epoxy resin composition. The method of the curing treatment can be appropriately selected according to the configuration of the epoxy resin composition, the purpose of the cured epoxy resin composition, and the like, and is preferably a heating and pressure treatment.
For example, a cured epoxy resin composition can be obtained by heating an uncured or semi-cured epoxy resin composition at 100 ° C. to 250 ° C. for 1 hour to 10 hours, preferably 130 ° C. to 230 ° C. for 1 hour to 8 hours. can get.

[Metal foil with resin]
The metal foil with resin of this embodiment includes a metal foil and a semi-cured resin composition layer derived from an epoxy resin composition disposed on the metal foil. By having the semi-cured resin composition layer derived from the epoxy resin composition, it is excellent in thermal conductivity and electrical insulation. The semi-cured resin composition layer can be obtained by heat-treating the epoxy resin composition until it reaches a B stage state.

It does not restrict | limit especially as metal foil, Gold foil, copper foil, aluminum foil etc. are mentioned, Generally copper foil is used.
The thickness of the metal foil is, for example, 1 μm to 35 μm, and is preferably 20 μm or less from the viewpoint of flexibility.
The metal foil is a three-layer composite foil in which nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as intermediate layers and copper layers are provided on both sides. A composite foil having a three-layer structure in which metal layers are provided on both surfaces or a composite foil having a two-layer structure in which aluminum and copper foil are combined can be used. In the composite foil having a three-layer structure in which the copper layer is provided on both surfaces of the intermediate layer, it is preferable that the thickness of one copper layer is 0.5 μm to 15 μm and the thickness of the other copper layer is 10 μm to 300 μm. .

The resin-attached metal foil forms, for example, a resin layer (resin sheet) by applying and drying an epoxy resin composition (preferably a resin varnish) on the metal foil, and heat-treating this to a B-stage state. Can be manufactured. The method for forming the resin layer is as described above.

The production conditions of the metal foil with resin are not particularly limited, and it is preferable that 80% by mass or more of the organic solvent used in the resin varnish is volatilized in the resin sheet after drying. The drying temperature is not particularly limited and is preferably about 80 to 180 ° C. The drying time can be appropriately selected in consideration of the gelation time of the resin varnish. The application amount of the resin varnish is preferably applied so that the thickness of the resin layer after drying is 50 μm to 350 μm, and more preferably 60 μm to 300 μm.
The dried resin sheet is further heat-treated to be in a B stage state. The conditions for heat-treating the resin composition are the same as those for the B-stage sheet.

[Metal substrate]
The metal substrate of the present embodiment includes a metal support, a cured epoxy resin composition layer derived from the epoxy resin composition disposed on the metal support, and a metal foil disposed on the cured epoxy resin composition layer. Are provided in this order. When the epoxy resin composition layer including the epoxy resin composition disposed between the metal support and the metal foil is formed by heat treatment so as to be in a cured state, adhesiveness, thermal conductivity, and Excellent electrical insulation.

The material and thickness of the metal support can be appropriately selected according to the purpose. Specifically, a metal such as aluminum or iron can be used and the thickness can be set to 0.5 mm to 5 mm.

The metal foil disposed on the cured resin composition layer is synonymous with the metal foil in the resin-attached metal foil, and the preferred embodiment is also the same.

The metal substrate of the present embodiment can be manufactured as follows, for example. On a metal support such as aluminum, an epoxy resin composition is applied and dried in the same manner as described above to form a resin layer. Further, a metal foil is disposed on the resin layer, and this is heated and pressurized. And it can manufacture by hardening | curing a resin layer. In addition, after the resin-coated metal foil is laminated on the metal support so that the resin layer faces the metal support, the resin layer can be heated and pressurized to cure the resin layer. .

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.

The material used for preparation of an epoxy resin composition and its abbreviation are shown below.
(Epoxy compound A (resin A) having a mesogenic skeleton)
[4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate, epoxy equivalent: 212 g / eq, by the method described in JP 2011-74366 A Manufacturing]

(Epoxy compound B having mesogenic skeleton (resin B))
[4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) -3-methylbenzoate, epoxy equivalent: 219 g / eq, disclosed in JP 2011-74366 A Manufactured by the described method]

(Other epoxy compounds having a mesogenic skeleton)
YL6121H [Biphenyl type epoxy compound, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 172 g / eq]

(Epoxy compound without mesogenic skeleton)
828EL [liquid bisphenol A type epoxy compound, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / eq]

(Inorganic filler)
AA-3 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 3 μm]
AA-04 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 0.40 μm]
HP-40 [boron nitride particles, manufactured by Mizushima Alloy Iron Co., Ltd., D50: 40 μm]

(Curing agent)
CRN [catechol resorcinol novolak (mass-based charge ratio: catechol / resorcinol = 5/95) resin, containing 50% by mass of cyclohexanone]

<Synthesis method of CRN>
A 3 L separable flask equipped with a stirrer, a cooler and a thermometer was charged with 627 g of resorcinol, 33 g of catechol, 316.2 g of a 37 mass% formaldehyde aqueous solution, 15 g of oxalic acid, and 300 g of water, and heated while heating in an oil bath. The temperature was raised to ° C. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system to obtain the target phenol novolac resin CRN.
Further, when the structure of the obtained CRN was confirmed by FD-MS (field desorption ionization mass spectrometry), all the partial structures represented by the general formulas (III-1) to (III-4) were confirmed. Existence was confirmed.

Note that, under the above reaction conditions, a compound having a partial structure represented by the general formula (III-1) is formed first, and this is further subjected to a dehydration reaction, whereby the general formulas (III-2) to (III-4) It is considered that a compound having a partial structure represented by at least one of

About the obtained CRN, Mn (number average molecular weight) and Mw (weight average molecular weight) were measured as follows.
Mn and Mw were measured using a high performance liquid chromatography (manufactured by Hitachi, Ltd., trade name: L6000) and a data analyzer (manufactured by Shimadzu Corporation, trade name: C-R4A). As analytical GPC columns, G2000HXL and G3000HXL (trade names) manufactured by Tosoh Corporation were used. The sample concentration was 0.2% by mass, tetrahydrofuran was used as the mobile phase, and the measurement was performed at a flow rate of 1.0 mL / min. A calibration curve was prepared using a polystyrene standard sample, and Mn and Mw were calculated using polystyrene conversion values.

With respect to the obtained CRN, the hydroxyl equivalent was measured as follows.
The hydroxyl equivalent was measured by acetyl chloride-potassium hydroxide titration method. The determination of the titration end point was performed by potentiometric titration instead of the coloring method using an indicator because the solution color was dark. Specifically, the hydroxyl group of the measurement resin is acetylated in a pyridine solution, the excess reagent is decomposed with water, and the resulting acetic acid is titrated with a potassium hydroxide / methanol solution.

The obtained CRN is a mixture of compounds having a partial structure represented by at least one of the general formulas (III-1) to (III-4), and Ar is represented by the general formula (III-a ) In which R ³¹ is a hydroxyl group, and R ³² and R ³³ are hydrogen atoms, a group derived from 1,2-dihydroxybenzene (catechol) and a group derived from 1,3-dihydroxybenzene (resorcinol), It was a novolak resin containing a curing agent (hydroxyl equivalent 62 g / eq, number average molecular weight 422, weight average molecular weight 564) containing 35% by mass of a monomer component (resorcinol) as a molecular diluent.

(Curing accelerator)
・ TPP: Triphenylphosphine [Wako Pure Chemical Industries, Ltd., trade name]

(Additive)
KBM-573: 3-phenylaminopropyltrimethoxysilane [silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd., trade name]

(solvent)
CHN: cyclohexanone

(Support)
PET film [manufactured by Teijin DuPont Films, trade name: A53, thickness 50 μm]
Copper foil [Furukawa Electric Co., Ltd., thickness: 105 μm, GTS grade]

Example 1
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, resin A and YL6121H were mixed so that the epoxy equivalent was 9: 1, whereby an epoxy mixture 1 was obtained. When the compatibility was confirmed by the method described later, the epoxy mixture 1 was compatible at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.94% by mass of epoxy mixture 1, 5.13% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, 9.81% by mass of AA-3, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.76% by mass of CHN as a solvent were mixed. An epoxy resin varnish 1 was obtained as an epoxy resin composition containing a solvent.

The density of boron nitride (HP-40) is 2.20 g / cm ³ , the density of alumina (AA-3 and AA-04) is 3.98 g / cm ³ , and an epoxy compound (resins A and YL6121H) and a curing agent ( The density of the mixture with CRN) was 1.20 g / cm ^{3 and} the ratio of the inorganic filler to the total volume of the total solid content of the epoxy resin composition was calculated to be 72% by volume.

<Preparation of B Stage Epoxy Resin Composition>
The epoxy resin varnish 1 is applied on a PET film using an applicator so that the thickness after drying is 200 μm, and then dried at room temperature (20 ° C. to 30 ° C.) for 5 minutes and further at 130 ° C. for 5 minutes. It was. Then, hot pressurization (press temperature: 150 ° C., degree of vacuum: 1 kPa, press pressure: 15 MPa, pressurization time: 1 minute) was performed by a vacuum press to obtain a B-stage epoxy resin composition.

<Preparation of cured epoxy resin composition with copper foil>
The PET film of the B-stage epoxy resin composition obtained above was peeled off, and then sandwiched between two copper foils so that the mat surface of the copper foil faces the semi-cured epoxy resin composition, respectively. And vacuum thermocompression bonding (press temperature: 180 ° C., degree of vacuum: 1 kPa, press pressure: 15 MPa, pressurization time: 6 minutes). Then, it heated at 150 degreeC for 2 hours and 210 degreeC for 4 hours under atmospheric pressure conditions, and the cured epoxy resin composition 1 with a copper foil was obtained.

<Evaluation>
The following evaluation was performed about the epoxy mixture 1 and the cured epoxy resin composition 1 obtained above. The evaluation results are shown in Table 1.

(Measurement of thermal conductivity)
The copper foil of the cured epoxy resin composition with copper foil 1 obtained above was removed by etching to obtain a sheet-like cured epoxy resin composition (cured resin sheet). The obtained resin sheet cured product was cut into 10 mm length and 10 mm width to obtain a sample. After the sample was blackened with graphite spray, the thermal diffusivity was evaluated by a xenon flash method (trade name: LFA447 nanoflash, manufactured by NETZSCH). From the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (Differential Scanning Calorimeter; product name: DSC Pyris 1 manufactured by Perkin Elmer), the thickness of the cured resin sheet is determined. The thermal conductivity was determined. The results are shown in Table 1.

(Confirmation of smectic structure formation)
The copper foil of the cured epoxy resin composition with copper foil 1 obtained above was removed by etching to obtain a sheet-like cured epoxy resin composition (cured resin sheet). The obtained resin sheet cured product was cut into 10 mm length and 10 mm width to obtain a sample. The sample was subjected to X-ray diffraction measurement (using an X-ray diffractometer manufactured by Rigaku Corporation) with a tube voltage of 40 kV, a tube current of 20 mA, and a range of 2θ of 0.5 to 30 ° using a CuK _α1 wire. Smectic structure formation was confirmed by the presence or absence of a diffraction peak in the range of ˜10 °.

(Confirmation of liquid crystal phase)
While heating the epoxy mixture 1 obtained above, the state change of the epoxy mixture 1 during heating was observed in a crossed Nicol state (magnification: 100 times) using a polarizing microscope (BS 51, manufactured by Olympus Corporation).
A transition from a crystal phase to a liquid crystal phase, which was in a fluid state while showing interference fringes due to depolarization, was observed at 120 ° C. Further, when the heating was further continued, a transition from a liquid crystal phase to an isotropic phase changing to a dark field was observed at 170 ° C.
The epoxy mixture 1 obtained above showed a liquid crystal phase at 120 ° C. to 170 ° C.

(Melting point measurement)
About the epoxy mixture 1 obtained above, it measured using the differential scanning calorimeter DSC7 (made by Perkin Elma). Differential scanning calorimetry of 3 mg to 5 mg samples sealed in an aluminum pan is performed under the conditions of a nitrogen atmosphere with a measurement temperature range of 25 ° C. to 350 ° C., a heating rate of 10 ° C./min, and a flow rate of 20 ± 5 ml / min. The temperature at which the energy change associated with the phase transition occurs (the temperature of the endothermic reaction peak) was defined as the melting point (phase transition temperature).

(Compatibility)
About the epoxy mixture 1 obtained above, it was heated to the isotropic phase transition temperature or higher and melted. Thereafter, the state of the cured product at 140 ° C., which is the curing temperature of the epoxy resin composition, was observed with a microscope (BS 51, manufactured by Olympus Corporation) while naturally cooling (magnification: 100 times). No phase separation of epoxy mixture 1 was observed.
That is, the epoxy mixture 1 obtained above had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

(Example 2)
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, resin A and YL6121H were mixed so that the epoxy equivalent was 8: 2, and an epoxy mixture 2 was obtained. When the compatibility was confirmed by the method described above, the epoxy mixture 2 had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.90% by mass of epoxy mixture 2, 5.21% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 Resin containing 9.81% by weight, 9.81% by weight of AA-04, 0.06% by weight of KBM-573 as additive, and 22.72% by weight of CHN as solvent. Epoxy resin varnish 2 was obtained as a composition.

B-stage epoxy resin composition 2 and cured epoxy resin composition 2 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 2 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 1.

(Example 3)
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogen skeleton, the resin A and the resin B were mixed so that the epoxy equivalent was 9: 1 to obtain an epoxy mixture 3. When compatibility was confirmed by the above-described method, the epoxy mixture 3 had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.98% by mass of epoxy mixture 3, 5.05% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 9.81% by mass of AA-04, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.80% by mass of CHN as a solvent, and an epoxy resin containing a solvent An epoxy resin varnish 3 was obtained as a composition.

The density of boron nitride (HP-40) is 2.20 g / cm ³ , the density of alumina (AA-3 and AA-04) is 3.98 g / cm ³ , and the epoxy compound (resin A and resin B) and curing agent When the density of the mixture with (CRN) was 1.20 g / cm ^{3 and} the ratio of the inorganic filler to the total volume of the total solid content of the epoxy resin composition was calculated, it was 72% by volume.

B-stage epoxy resin composition 3 and cured epoxy resin composition 3 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 3 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 1.

Example 4
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, the resin A and the resin B were mixed so that the epoxy equivalent was 7: 3 to obtain an epoxy mixture 4. When the compatibility was confirmed by the method described above, the epoxy mixture 4 was compatible at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.98% by mass of epoxy mixture 4, 5.05% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 9.81% by mass of AA-04, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.80% by mass of CHN as a solvent, and an epoxy resin containing a solvent Epoxy resin varnish 4 was obtained as a composition.

A B-stage epoxy resin composition 4 and a cured epoxy resin composition 4 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 4 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 1.

(Comparative Example 1)
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, resin A and YL6121H were mixed so that the epoxy equivalent was 7: 3, whereby an epoxy mixture 5 was obtained. When the compatibility was confirmed by the method described above, the epoxy mixture 5 had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.85% by mass of epoxy mixture 5, 5.30% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 9.81% by mass of AA-04, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.68% by mass of CHN as a solvent, and an epoxy resin containing a solvent An epoxy resin varnish 5 was obtained as a composition.

A B-stage epoxy resin composition 5 and a cured epoxy resin composition 5 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 5 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2. In Table 2, “-” means that the component is not added and the mixing ratio is not calculated.

(Comparative Example 2)
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, resin A and YL6121H were mixed so that the epoxy equivalent was 6: 4, whereby an epoxy mixture 6 was obtained. When the compatibility was confirmed by the method described above, the epoxy mixture 6 was compatible at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.81% by mass of epoxy mixture 6, 5.39% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA- 3 is 9.81% by mass, AA-04 is 9.81% by mass, KBM-573 is added as an additive, 0.06% by mass, CHN as a solvent is mixed with 22.63% by mass, and an epoxy resin containing a solvent is mixed. Epoxy resin varnish 6 was obtained as a composition.

B-stage epoxy resin composition 6 and cured epoxy resin composition 6 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 6 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 3)
<Preparation of epoxy resin composition>
As an epoxy compound having a mesogenic skeleton, resin A and YL6121H were mixed so that the epoxy equivalent was 5: 5 to obtain an epoxy mixture 7. When the compatibility was confirmed by the method described above, the epoxy mixture 7 had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.76% by mass of epoxy mixture 7, 5.49% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 Resin containing 9.81% by weight, 9.81% by weight of AA-04, 0.06% by weight of KBM-573 as an additive, and 22.58% by weight of CHN as a solvent. Epoxy resin varnish 7 was obtained as a composition.

B-stage epoxy resin composition 7 and cured epoxy resin composition 7 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 7 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 4)
<Preparation of epoxy resin composition>
Resin A as an epoxy compound having a mesogen skeleton and 828EL as an epoxy compound not having a mesogen skeleton were mixed so that an epoxy equivalent was 9: 1 to obtain an epoxy mixture 8. When the compatibility was confirmed by the method described above, the epoxy mixture 8 had compatibility at 140 ° C., which is the curing temperature of the epoxy resin composition.

8.96% by mass of epoxy mixture 8, 5.10% by mass of CRN as a curing agent, 0.09% by mass of TPP as a curing accelerator, 43.40% by mass of HP-40 as an inorganic filler, AA-3 9.81% by mass of AA-04, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.77% by mass of CHN as a solvent, and an epoxy resin containing a solvent Epoxy resin varnish 8 was obtained as a composition.

The density of boron nitride (HP-40) is 2.20 g / cm ³ , the density of alumina (AA-3 and AA-04) is 3.98 g / cm ³ , and an epoxy compound (resins A and 828EL) and a curing agent ( The density of the mixture with CRN) was 1.20 g / cm ^{3 and} the ratio of the inorganic filler to the total volume of the total solid content of the epoxy resin composition was calculated to be 72% by volume.

B-stage epoxy resin composition 8 and cured epoxy resin composition 8 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 8 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 5)
<Preparation of epoxy resin composition>
Resin A is 8.99% by mass as an epoxy compound having a mesogenic skeleton, CRN is 5.04% by mass as a curing agent, TPP is 0.09% by mass as a curing accelerator, and HP-40 is 43.40 as an inorganic filler. % By weight, 9.81% by weight of AA-3, 9.81% by weight of AA-04, 0.06% by weight of KBM-573 as an additive, and 22.80% by weight of CHN as a solvent. An epoxy resin varnish 9 was obtained as an epoxy resin composition containing a solvent.

The density of boron nitride (HP-40) is 2.20 g / cm ³ , the density of alumina (AA-3 and AA-04) is 3.98 g / cm ³ , and the epoxy compound (resin A) and curing agent (CRN) The density of the mixture was calculated as 1.20 g / cm ^{3 and} the ratio of the inorganic filler to the total volume of the total solid content of the epoxy resin composition was calculated to be 72% by volume.

B-stage epoxy resin composition 9 and cured epoxy resin composition 9 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 9 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 6)
<Preparation of epoxy resin composition>
Resin B is 8.97% by mass as an epoxy compound having a mesogenic skeleton, CRN is 5.08% by mass as a curing agent, TPP is 0.09% by mass as a curing accelerator, and HP-40 is 43.40 as an inorganic filler. % By weight, 9.81% by weight of AA-3, 9.81% by weight of AA-04, 0.06% by weight of KBM-573 as an additive, and 22.78% by weight of CHN as a solvent. An epoxy resin varnish 10 was obtained as an epoxy resin composition containing a solvent.

A B-stage epoxy resin composition 10 and a cured epoxy resin composition 10 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 10 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 7)
<Preparation of epoxy resin composition>
As another epoxy compound having a mesogenic skeleton, YL6121H is 8.50 mass%, CRN is 6.02 mass% as a curing agent, TPP is 0.09 mass% as a curing accelerator, and HP-40 is 43.3% as an inorganic filler. 40% by mass, 9.81% by mass of AA-3, 9.81% by mass of AA-04, 0.06% by mass of KBM-573 as an additive, and 22.31% by mass of CHN as a solvent were mixed. Thus, an epoxy resin varnish 11 was obtained as an epoxy resin composition containing a solvent.

The density of boron nitride (HP-40) is 2.20 g / cm ³ , the density of alumina (AA-3 and AA-04) is 3.98 g / cm ³ , and an epoxy compound (YL6121H) and a curing agent (CRN) The density of the mixture was 1.20 g / cm ³ , and the ratio of the inorganic filler to the total volume of the total solid content of the epoxy resin composition was calculated to be 72% by volume.

A B-stage epoxy resin composition 11 and a cured epoxy resin composition 11 were prepared in the same manner as in Example 1 except that the epoxy resin varnish 11 obtained above was used, and evaluated in the same manner as described above. The results are shown in Table 2.

As shown in Tables 1 and 2, the thermal conductivity is highest in Comparative Example 5 using only the resin A. When the resin A and YL6121H were used together as the epoxy compound, the resin A and the resin B were used together, and the resin A and the 828EL were used together, they were compatible with each other. Moreover, when Resin A and YL6121H, or Resin A and Resin B were used in combination, the melting point was lower by 10 ° C. or more than when Resin A was used alone.
The epoxy resin composition that is compatible with each other and has a smectic structure has higher thermal conductivity than an epoxy resin composition that does not have a smectic structure. From this, it can be seen that the thermal conductivity varies greatly depending on the presence or absence of the smectic structure.
As described above, an epoxy resin composition having a low melting point and a high thermal conductivity can be obtained.

The entire disclosure of Japanese Patent Application No. 2016-111371 is incorporated herein by reference. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims

Containing two or more epoxy compounds having a mesogenic skeleton, a curing agent, and an inorganic filler,
2 or more types of epoxy compounds which have the said mesogen skeleton are mutually compatible, The epoxy resin composition which can form a smectic structure by reacting with the said hardening | curing agent.
2. The epoxy resin composition according to claim 1, wherein the two or more epoxy compounds having a mesogenic skeleton include at least one compound represented by the following general formula (I).

[In general formula (I), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]
The epoxy resin composition according to claim 1 or 2, wherein the curing agent contains a phenol novolac resin.
The hardener contains a novolak resin having a structural unit represented by at least one selected from the group consisting of the following general formula (II-1) and the following general formula (II-2). 4. The epoxy resin composition according to any one of 3 above.

[In General Formula (II-1) and General Formula (II-2), R 21 and R 24 each independently represents an alkyl group, an aryl group, or an aralkyl group. R 22 , R 23 , R 25 and R 26 each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represents an integer of 0-2. n21 and n22 each independently represents an integer of 1 to 7. ]
The hardener contains a novolak resin having a partial structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4): 4. The epoxy resin composition according to any one of 3 above.

[In the general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar 31 to Ar 34 each independently represents any of the groups represented by the following general formula (III-a) or the following general formula (III-b). ]

[In General Formula (III-a) and General Formula (III-b), R 31 and R 34 each independently represent a hydrogen atom or a hydroxyl group. R 32 and R 33 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ]
6. The curing agent according to claim 1, wherein the curing agent contains a monomer that is a phenol compound constituting the novolak resin, and the content of the monomer is 5% by mass to 80% by mass in the curing agent. 2. The epoxy resin composition according to item 1.
The epoxy resin composition according to any one of claims 1 to 6, wherein the inorganic filler includes at least one selected from the group consisting of boron nitride, alumina, magnesium oxide, silica, and aluminum nitride.
The epoxy resin composition according to any one of claims 1 to 7, wherein a content of the inorganic filler exceeds 50% by volume in a solid content.
A B stage sheet which is a sheet-like semi-cured product of the epoxy resin composition according to any one of claims 1 to 8.
A cured epoxy resin composition, which is a cured product of the epoxy resin composition according to any one of claims 1 to 8.
A resin sheet which is a sheet-like formed body of the epoxy resin composition according to any one of claims 1 to 8.
A metal foil with a resin, comprising: a metal foil; and a semi-cured epoxy resin composition layer derived from the epoxy resin composition according to any one of claims 1 to 8 disposed on the metal foil.
A cured epoxy resin composition layer derived from the epoxy resin composition according to any one of claims 1 to 8, disposed on the metal support, and the cured epoxy resin composition A metal substrate comprising a metal foil disposed on the layer in this order.