TW201815865A - Epoxy resin composition, B stage sheet, cured epoxy resin composition, resin sheet, metal foil with resin, and metal substrate - Google Patents

Abstract

An epoxy resin composition includes a curing agent, an inorganic filler, and two or more epoxy compounds each having a mesogenic skeleton, the two or more epoxy compounds being compatible with each other, and a smectic structure being able to be formed by the two or more epoxy compounds reacting with the curing agent.

Description

Epoxy resin composition, B-stage sheet, hardened 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 resin-attached metal foil, and a metal substrate.

In recent years, there has been a tendency for heat generation to increase due to miniaturization of electronic and electrical equipment. Therefore, how to dissipate heat in an insulating material becomes an important problem. As an insulating material which can be used in these machines, a thermosetting resin cured product is widely used from the viewpoints of insulation properties, heat resistance and the like. However, in general, since the thermal curable resin cured product has a low thermal conductivity and is a major cause of hindering heat dissipation, a thermosetting resin cured product having high thermal conductivity is desired.

As a cured product of a thermosetting resin having high thermal conductivity, a cured product of an epoxy resin composition having a liquid crystal original skeleton in a molecular structure has been proposed (for example, see Patent Document 1). Further, as a thermosetting resin having high thermal conductivity and a low softening point (melting point), a modified epoxy resin obtained by reacting biphenol with a mixed epoxy resin, which is obtained by reacting, is proposed. The resin is composed of a glycidyl compound of 4,4'-dihydroxybiphenylmethane and a glycidyl compound of biphenol (for example, refer to Patent Document 2).

It is known that an epoxy compound having a liquid crystal original skeleton can exhibit a narrow temperature region of a liquid crystal, and when it is melt-mixed and hardened below a hardening temperature, since it is only limited to hardening in a specific temperature range. In order to exhibit liquid crystallinity, it is difficult to easily obtain an epoxy resin cured product which exhibits liquid crystallinity. A resin composition capable of easily producing a resin cured product having high thermal conductivity as a range of a hardening temperature at the time of producing a cured resin, and a resin composition containing a plurality of epoxy compounds, which has been reported, has been reported. The oxygen compound has a specific liquid crystal original skeleton in the molecular structure (for example, refer to Patent Documents 3 and 4). Further, there has been proposed an insulating composition in which a liquid crystalline polymer and a thermosetting resin are separated from each other (for example, see Patent Document 5). Further, it has been reported that a liquid crystalline polymer contributes to high thermal conductivity in an insulating composition, and a thermosetting resin contributes to adhesion to a metal such as copper. [Previous Technical Literature] (Patent Literature)

Patent Document 1: Japanese Patent No. 4,118, 691, and Patent Document 2: Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. Japanese Special Open 2010-18679

[Problems to be Solved by the Invention] However, in general, an epoxy resin having a liquid crystal original skeleton in a molecular structure has a higher melting point and a higher melting point, and may cause workability such as molding conditions to become Strict. In particular, if the epoxy resin has a high melting point, since the high temperature is required to melt the epoxy resin, the heat curing temperature becomes high. If the temperature is raised in order to melt the epoxy resin, the reaction speed of the epoxy resin and the hardener becomes faster. Therefore, the high melting point epoxy resin is liable to start the reaction with the hardener before it is sufficiently melted. Therefore, in the resin compositions of Patent Document 3 and Patent Document 4, since the heat curing temperature is high, the liquid crystal original skeleton is hardened before being aligned, and thus the thermal conductivity of the epoxy resin itself may not be sufficiently exhibited. Moreover, since the thermosetting resin of the patent document 2 is not easy to synthesize, it is desired to develop a new epoxy resin which can improve both a low melting point and thermal conductivity.

According to the present invention, it is possible to provide a resin composition capable of achieving both a low melting point and an improvement in thermal conductivity after hardening; and a B-stage sheet and hardening using the epoxy resin composition An epoxy resin composition, a resin sheet, a metal foil with a resin, and a metal substrate. [Technical means to solve the problem]

The following embodiments include specific means for solving the above problems.

<1> An epoxy resin composition containing two or more epoxy compounds having a liquid crystal primary skeleton, a curing agent, and an inorganic filler; wherein the two or more epoxy compounds having a liquid crystal primary skeleton are mutually compatible And capable of forming a smectic structure by reacting with the aforementioned hardener.

<2> The epoxy resin composition according to the above-mentioned item, wherein the epoxy compound having two or more kinds of the liquid crystal primary skeletons contains at least one compound represented by the following formula (I).

In the formula (I), R ¹ to R ⁴ each independently represent 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 contains a phenol novolak resin.

The epoxy resin composition according to any one of <1> to <3> wherein the hardener comprises a novolak resin having a selected from the group consisting of the following formula (II- 1) A structural unit represented by at least one of the group consisting of the following formula (II-2).

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

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

In the general formulae (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer, and Ar ³¹ to Ar ³⁴ each independently represent the following general formula (III-a). Or any one group represented by the following formula (III-b).

In the formula (III-a) and the 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 represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

The epoxy resin composition as described in any one of the above-mentioned [1], wherein the said hardening agent contains the monomer of the phenol compound which comprises the said no The rate is 5 mass% to 80 mass% in the hardener.

The epoxy resin composition according to any one of <1> to <6> wherein the inorganic filler material is selected from the group consisting of boron nitride, aluminum oxide, magnesium oxide, cerium oxide, and aluminum nitride. At least one of the group consisting of.

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

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

<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 sheet-like molded article of the epoxy resin composition according to any one of <1> to <8>.

<12> A metal foil with a resin, comprising: a metal foil; and a semi-hardened epoxy resin composition layer, which is obtained from the epoxy resin composition according to any one of <1> to <8> And is disposed on the aforementioned metal foil.

<13> A metal substrate comprising: a metal support; and a cured epoxy resin composition layer, which is obtained from the epoxy resin composition according to any one of <1> to <8>, and is configured On the metal support; and a metal foil disposed on the hardened epoxy resin composition layer. [Effects of the Invention]

According to the present invention, it is possible to provide a resin composition capable of achieving both a low melting point and an improvement in thermal conductivity after hardening; and a B-stage sheet and hardening using the epoxy resin composition An epoxy resin composition, a resin sheet, a metal foil with a resin, and a metal substrate.

Hereinafter, the form for carrying out the invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including the elemental steps) are not necessarily included unless otherwise specified. The same values and ranges are also not intended to limit the invention. In the present specification, the term "step" is used in addition to the steps of other steps, and even if it is not clearly distinguishable from other steps, it is included in the step as long as the desired purpose of the step can be achieved. In the present specification, the numerical range indicated by "~" means that the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical range stated in the specification, the upper or lower limit of the numerical range stated in a certain stage may be replaced with the upper or lower limit of the numerical range stated in other stages. . Further, in the numerical ranges described in the present specification, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples. In the present specification, a plurality of substances corresponding to the respective components may be contained. When a plurality of substances corresponding to the respective components are present in the composition, the content rate or content of each component means the total content or content of the plurality of substances present in the composition unless otherwise specified. In the present specification, a plurality of particles corresponding to the respective components may be contained. When a plurality of particles corresponding to the respective components are present in the composition, the particle diameter of each component means the value of the mixture of the plurality of particles present in the composition unless otherwise specified. In the present specification, the term "layer" means that when a region in which the layer exists is observed, a case where only a part of the region is formed is included in addition to the entire region. In the present specification, the term "layered" means that layers are stacked and overlapped, and two or more layers may be bonded to each other, or two or more layers may be separated from each other.

The number of structural units represents an integer value for a single molecule, and as a collection of a plurality of molecules, the average value is a rational number.

The following resin sheet is sometimes referred to as a B-stage sheet obtained by further subjecting a resin sheet obtained by drying an epoxy resin composition layer to heat and pressure treatment, and the epoxy resin composition layer is An epoxy resin composition is formed. Further, the B-stage sheet is defined in accordance with the definition of Japanese Industrial Standard JIS K6900:1994.

<Epoxy resin composition> The epoxy resin composition of the present embodiment contains two or more kinds of epoxy compounds having a liquid crystal original skeleton, a curing agent, and an inorganic filler; wherein the two or more types have a liquid crystal original skeleton. The epoxy compounds are compatible with each other and can form a smectic structure by reacting with the aforementioned hardener. According to such a configuration, the epoxy resin composition of the present embodiment can improve both the low melting point and the thermal conductivity after curing. Although the reason is still unclear, it can be presumed as follows. It is considered that the epoxy resin composition contains two or more epoxy compounds having a liquid crystal original skeleton, and the two or more epoxy compounds having a liquid crystal primary skeleton are compatible with each other to form a smectic structure. The melting point of the epoxy resin composition before curing can be lowered, and high thermal conductivity can be exhibited after curing. 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 kinds of epoxy compounds having a liquid crystal original skeleton, and the epoxy compounds having a liquid crystal original skeleton are compatible with each other. It has been found that the melting point of a mixture of epoxy compounds having two or more liquid crystal primary skeletons compatible with each other (hereinafter, also referred to as "epoxy mixture") becomes lower than that of the epoxy compound. The melting point of the epoxy compound having the liquid crystal original skeleton having the highest melting point among the epoxy compounds having a liquid crystal original skeleton. Therefore, the low melting point of the epoxy resin composition can be exhibited. Further, when the epoxy resin composition is made into a semi-cured material or a cured product, the thermal conductivity can be higher than when a single epoxy compound having a liquid crystal original skeleton constituting the epoxy mixture is made into a semi-cured or cured product. Thermal conductivity. When the epoxy mixture contains three or more epoxy compounds having a liquid crystal original skeleton, the epoxy mixture may be compatible as a whole, or may be selected from three or more epoxy compounds having a liquid crystal original skeleton. Any two kinds of epoxy compounds having a liquid crystal original skeleton which are not compatible with each other, and which are composed of all epoxy compounds having a liquid crystal original skeleton constituting the epoxy mixture. In the present specification, the term "two or more types of epoxy compounds" means two or more types of epoxy compounds having different molecular structures. However, two or more kinds of epoxy compounds which are mutually stereoisomers (optical isomers, geometric isomers) do not belong to "two or more kinds of epoxy compounds", but are regarded as the same type of epoxy. Compound. The epoxy compound in the present embodiment may be an epoxy monomer or an epoxy resin, and is preferably an epoxy monomer from the viewpoint of high order structure formation property (high thermal conductivity). The epoxy mixture may be a combination of an epoxy monomer and an epoxy monomer, may be a combination of an epoxy monomer and an epoxy resin, or a combination of an epoxy resin and an epoxy resin, forming a high-order structure (high From the viewpoint of thermal conductivity, a combination of an epoxy monomer and an epoxy monomer is preferred.

In the present specification, the term "liquid crystal original skeleton" means a molecular structure having a possibility of exhibiting liquid crystallinity. Specific examples thereof include a biphenyl skeleton, a phenyl benzoate skeleton, an azobenzene skeleton, a stilbene skeleton, and the like. An epoxy resin composition containing an epoxy compound having a liquid crystal original skeleton tends to form a high-order structure upon hardening, and tends to have a higher thermal conductivity when formed into a cured product.

Here, the high-order structure is a state in which the constituent elements are minutely arranged, and corresponds to, for example, a crystal phase and a liquid crystal phase. Whether such a high-order structure exists or not can be easily judged by observation with a polarizing microscope. That is, in the observation of the crossed-nicol state, it is possible to judge that a high-order structure exists due to the interference pattern generated by depolarization. Higher order structures, usually in the form of islands in the resin, form a domain structure. Also, the islands forming the regional structure are each referred to as a high-order structure. The structural units constituting the higher-order structure are generally bonded to each other by a covalent bond.

A highly regular high-order structure derived from a liquid crystal original skeleton has a nematic structure, a smectic structure, or the like. The nematic structure is oriented in the same direction as the long axis of the molecule and is a liquid crystal structure having only an orientational order. In contrast to this, the smectic structure has a one-dimensional position order in addition to the positioning order, and is a liquid crystal structure having a layer structure of a specific period. Further, in the inside of the structure of the same period of the smectic structure, the direction of the period of the layer structure is the same. That is, the order of the molecules of the smectic structure is higher than that of the nematic structure. If a high order structure with high order is formed in the semi-hardened or hardened material, the scattering of the medium of heat conduction, that is, phonon, can be suppressed. Therefore, the thermal conductivity of the smectic structure becomes higher than that of the nematic structure. That is, the molecular order of the smectic structure is higher than that of the nematic structure, so that the thermal conductivity of the cured product also becomes higher in the case of expressing the smectic structure. It is considered that the epoxy resin composition can form a smectic structure because it can react with the curing agent, so that it can exhibit high thermal conductivity.

Whether or not the epoxy resin composition can form a smectic structure can be judged by the following method. X-ray diffraction measurement is performed using an X-ray analyzer (for example, manufactured by RIGAKU Co., Ltd.) in a range of a tube voltage of 40 kV, a tube current of 20 mA, and 2θ of 0.5 to 30° using a CuK _α 1 ray. When there is a diffraction peak in the range of 2° to 10° in 2θ, it can be judged that the periodic structure includes a smectic structure. Further, when there is a high-order structure derived from a high regularity of the liquid crystal original structure, a diffraction peak appears in the range of 2θ to 1° to 30°.

In the present specification, the term "compatible" means that a phase separation state derived from an epoxy compound having a liquid crystal original skeleton is not observed after the epoxy mixture is melted and naturally cooled; or, even in an epoxy The epoxy compound having a liquid crystal original skeleton in the mixture is phase-separated, but when a semi-hardened or cured product of the epoxy resin composition is formed, no phase separation state is observed.

Whether the epoxy compounds having the liquid crystal original skeleton are compatible with each other can be judged by the following operation. For example, it can be judged by heating the epoxy mixture to melt at a temperature higher than the isotropic phase of the epoxy mixture, and then, the molten epoxy mixture is naturally cooled, Then, an optical microscope image (magnification: 100 times) was observed to observe whether or not various epoxy compounds having a liquid crystal original skeleton contained in the epoxy mixture were phase-separated. Further, it can be judged by using the epoxy mixture as the epoxy resin composition, and observing the semi-hardened substance of the epoxy resin composition at the temperature at which the semi-hardened or cured product is formed, that is, the curing temperature. An optical microscope image (magnification: 100 times) of the cured product was observed to observe whether or not the various epoxy compounds having a liquid crystal original skeleton contained in the epoxy resin mixture were phase separated.

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

In addition to the above methods, whether or not the epoxy compounds having a liquid crystal original skeleton are compatible with each other can be inspected by observing a semi-hardened or cured product derived from an epoxy mixture using a scanning electron microscope (SEM). After cutting a cross section of the semi-hardened or hardened material derived from the epoxy mixture, for example, using a diamond cutter, grinding is performed using a sandpaper and a polishing liquid, and using SEM, for example, at 2000 magnification Magnification to observe the state of its profile. When the semi-hardened or cured product is an epoxy mixture composed of a combination of epoxy compounds which are freely phase-separated, phase separation can be clearly observed.

Further, it can be observed that the melting point of the epoxy mixture composed of the compatible combination of the epoxy compound having a liquid crystal original skeleton becomes lower than the epoxy compound having the liquid crystal original skeleton constituting the epoxy mixture. Among them, the melting point of the epoxy compound having the highest melting point of the liquid crystal original skeleton. The melting point referred to herein means an epoxy compound having a liquid crystal phase, and means a temperature at which an epoxy compound undergoes a phase transition from a liquid crystal phase to an equal phase. Further, the epoxy compound having no liquid crystal phase means a temperature at which the substance changes from a solid (crystalline phase) to a liquid (isomeric phase). The so-called liquid crystal phase is a phase in the middle of the crystalline state (crystalline phase) and the liquid state (isolateral phase), and means a state in which the molecular arrangement direction still retains a certain degree of order, but the three-dimensional has been lost. The order of the location.

The presence or absence of the liquid crystal phase can be judged by changing the state of the substance during the temperature rise of the substance by room temperature (for example, 25 ° C) by using a polarizing microscope. In the observation of the crossed-nicol state, the crystal phase and the liquid crystal phase can see the interference fringes due to the depolarized light, and the equilateral phase can be seen in the dark field. Further, the phase transition from the crystal phase to the liquid crystal phase can be confirmed by the presence or absence of fluidity. That is to say, the so-called liquid crystal phase is a temperature region having fluidity and having interference fringes due to depolarized light. That is, in the observation of the orthogonal polarization state, as long as it is confirmed that the epoxy compound or the epoxy mixture having the liquid crystal original skeleton has fluidity and has a temperature region in which interference fringes due to depolarization light are observed, It can be judged that the epoxy compound or the epoxy mixture having the liquid crystal original skeleton has a liquid crystal phase.

The epoxy mixture exhibits a range of the temperature range of the liquid crystal phase, preferably 10 ° C or more, more preferably 20 ° C or more, still more preferably 40 ° C or more. If the temperature region is 10 ° C or more, the cured product tends to have a high thermal conductivity. Further, if the range of the temperature region is larger, it is more preferable to obtain a cured product having a higher thermal conductivity.

Further, the melting point of the epoxy compound or the epoxy mixture having the liquid crystal original skeleton can be measured as a temperature at which an energy change (endothermic reaction) accompanying the phase transition occurs, and a differential scanning calorimeter (DSC) is used at 25 ° C to ～ The differential scanning calorimetry was carried out under the conditions of a temperature rise rate of 10 ° C / min in a temperature range of 350 ° C. From the viewpoint of workability and reactivity, the melting point of the epoxy compound or epoxy mixture having a liquid crystal original skeleton is preferably 120 ° C or lower.

The epoxy compounds having a liquid crystal original skeleton are compatible with each other, that is, have a tendency to exhibit an epoxy compound having a liquid crystal original skeleton in a semi-cured or cured product derived from an epoxy mixture. a state in which they are separated from each other; and even when a curing agent, an inorganic filler, or the like is added to an epoxy compound having a liquid crystal original skeleton to constitute an epoxy resin composition, in a semi-hardened or hardened body of the epoxy resin composition The epoxy compound having a liquid crystal original skeleton does not exhibit a state of being separated from each other.

The epoxy compound having two or more kinds of liquid crystal primary skeletons contained in the epoxy resin composition is not compatible unless it is compatible with each other and can form a smectic structure by reacting with a curing agent to be described later. The limitation can be appropriately selected from the epoxy compound having a liquid crystal original skeleton which is usually used. Examples of the epoxy compound having a liquid crystal original skeleton include an epoxy compound having a liquid crystal original skeleton and having two epoxypropyl groups in one molecule.

Examples of the epoxy compound having a liquid crystal original skeleton and having two epoxypropyl groups in one molecule include a biphenyl type epoxy compound and a tricyclic epoxy compound.

The biphenyl type epoxy compound may, for example, be an epoxy compound or the like which is such that 4,4'-bis(2,3-epoxypropoxy)biphenyl or 4,4'-bis (2) is used. , 3-epoxypropoxy)-3,3',5,5'-tetramethylbiphenyl is a main component of an epoxy compound, epichlorohydrin, and 4,4'-biphenol or 4, 4'-(3,3',5,5'-tetramethyl)biphenol is obtained by a reaction.

Examples of the 3-ring type epoxy compound include an epoxy compound having a triphenyl skeleton, and 1-(3-methyl-4-oxiranylmethoxyphenyl)-4-(4-epoxy B). Alkylmethoxyphenyl)-1-cyclohexane, 1-(3-methyl-4-oxiranylmethoxyphenyl)-4-(4-oxiranylmethoxy) Phenyl)-benzene, 4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropoxy)benzoate, and the like.

From the viewpoint of achieving a higher thermal conductivity, as an epoxy compound having a liquid crystal original skeleton and having two epoxypropyl groups in one molecule, it is preferred to use one of them as an epoxy compound for hardening. It is possible to form a high-order structure, and it is more preferable to form a smectic structure. The epoxy compound represented by the following formula (I) (hereinafter also referred to as "specific epoxy compound"). The epoxy resin composition can achieve higher thermal conductivity by including a specific epoxy compound.

In the formula (I), R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹ to R ⁴ each preferably independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom. Further, it is preferred that two to four of R ¹ to R ⁴ are a hydrogen atom, more preferably three or four are hydrogen atoms, and even more preferably all four are hydrogen atoms. When any of R ¹ to R ⁴ is an alkyl group having 1 to 3 carbon atoms, it is preferred that at least one of R ¹ and R ⁴ is an alkyl group having 1 to 3 carbon atoms.

Further, a preferred example of the specific epoxy compound is described, for example, in JP-A-2011-74366. Specifically, as the specific epoxy compound, it is preferably selected from 4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxyoxypropoxy) Benzoate, and 4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropoxy)-3-methyl At least one compound of the group consisting of benzoates.

From the viewpoint of high thermal conductivity, two or more epoxy compounds having a liquid crystal primary skeleton preferably contain at least one specific epoxy compound, and more preferably two or more specific epoxy compounds. The epoxy compound having a liquid crystal original skeleton constituting the epoxy mixture is a specific epoxy compound.

The epoxy resin composition may contain, in addition to a specific epoxy compound, a ring having a liquid crystal original skeleton which is different from a specific epoxy compound and compatible with a specific epoxy compound from the viewpoint of low melting point and thermal conductivity. Oxygen compound (hereinafter also referred to as "other epoxy compound having a liquid crystal original skeleton"). As the other epoxy compound having a liquid crystal original skeleton, it is preferred to use one type alone to form a nematic structure when it is cured as an epoxy compound. Examples of such an epoxy compound include a biphenyl type epoxy compound, and a biphenyl type epoxy compound is preferred from the viewpoint of easiness in purchasing materials, cost, and thermal conductivity.

The biphenyl type epoxy compound may, for example, be 4,4'-bis(2,3-epoxypropoxy)biphenyl. The biphenyl type epoxy compound is exemplified by the following product names: "YX4000", "YL6121H" (above, manufactured by Mitsubishi Chemical Corporation), "NC-3000", "NC-3100". (above, manufactured by Nippon Kayaku Co., Ltd.). Among the commercially available biphenyl type epoxy compounds, from the viewpoint of the improvement of the low melting point and the thermal conductivity, "YL6121H" (manufactured by Mitsubishi Chemical Corporation) is more preferable. The other epoxy compound having a liquid crystal original 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 liquid crystal original skeleton, as a mixture ratio of a specific epoxy compound and another epoxy compound having a liquid crystal original skeleton, it is desired to have both a low melting point and a heat conduction. From the viewpoint of the improvement of the rate of the epoxy resin, it is preferably in the range of 5:5 to 9.5:0.5 (specific epoxy compound: other epoxy compound having a liquid crystal original skeleton), and more preferably 6 The range of 4 to 9:1 is more preferably in the range of 7:3 to 9:1.

The epoxy resin composition may further comprise an epoxy compound having no liquid crystal original skeleton as long as the epoxy mixture reacts with a curing agent described later to form a smectic structure (hereinafter referred to as "non-liquid crystal original ring". Oxygen compound"). Examples of the non-liquid crystal raw epoxy compound include a bisphenol epoxy compound and a triphenylmethane epoxy compound. From the viewpoint of ease of purchase and cost, a bisphenol type epoxy compound is preferred.

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 exemplified by the following product names: "ZX1059", "VSLV-80XY" (above, manufactured by Nippon Steel Sumitomo Chemical Co., Ltd.), "828EL" (Mitsubishi Chemical) Manufacturing company). The triphenylmethane-based epoxy compound is not particularly limited as long as it is a compound having a triphenylmethane skeleton as a raw material, and is exemplified by the following product name: "1032H60" (Mitsubishi) Manufactured by Chemical Co., Ltd., "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd.).

The content of the non-liquid crystal raw epoxy compound in the epoxy mixture is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably 1% by mass or less.

The content of the specific epoxy compound in the epoxy mixture is not particularly limited as long as the epoxy mixture reacts with a curing agent to be described later and can form a smectic structure, and can be appropriately selected. From the viewpoint of the low melting point, the content of the epoxy compound having a liquid crystal original skeleton is preferably 5% by mass or more, more preferably 10% by mass to 100% by mass, based on the total mass of the epoxy mixture. Good is 100% by mass.

The total content of the epoxy compound having a liquid crystal original skeleton in the epoxy resin composition is not particularly limited. From the viewpoint of thermosetting property and thermal conductivity, the total content of the epoxy compound having a liquid crystal original skeleton is preferably from 3% by mass to 10% by mass, more preferably, based on the total mass of the epoxy resin composition. 5 mass% to 10 mass%.

[Hardener] The epoxy resin composition contains a hardener. The curing agent is not particularly limited as long as it can undergo a curing reaction with an epoxy compound having a liquid crystal original skeleton, and can be appropriately selected and used as a curing agent to be used. Specific examples of the curing agent include an acid-based curing agent, an amine-based curing agent, a phenol-based curing agent, and a thiol-based curing agent; and a catalyst-type curing agent such as imidazole. These hardeners may be used alone or in combination of two or more. In particular, it is preferable to use at least one selected from the group consisting of an amine-based curing agent and a phenol-based curing agent as a curing agent, and further, from the viewpoint of storage stability, from the viewpoint of heat resistance. More preferably, at least one of phenolic curing agents is used.

As the amine-based curing agent, those which are generally used as a curing agent for an epoxy compound can be used without particular limitation, and a commercially available amine-based curing agent can be used. In particular, from the viewpoint of curability, the amine-based curing agent is preferably a polyfunctional hardener having two or more functional groups, and more preferably a rigid skeleton having a rigid structure from the viewpoint of thermal conductivity. hardener.

Specific examples of the bifunctional amine-based curing agent include 4,4'-diamine diphenylmethane, 4,4'-diamine diphenyl ether, and 4,4'-diamine diphenyl hydrazine. , 4'-diamine-3,3'-dimethoxybiphenyl, benzoic acid-4,4'-diamine phenyl ester, 1,5-diamine naphthalene, 1,3-diamine naphthalene, 1,4 - Diamine naphthalene, 1,8-diamine naphthalene, and the like. Among them, from the viewpoint of thermal conductivity, it is preferably at least one selected from the group consisting of 4,4'-diamine diphenylmethane and 1,5-diamine naphthalene, more preferably 1,5. - Diamine naphthalene.

As the phenolic curing agent, those which are generally used as a curing agent for an epoxy compound can be used without particular limitation, and a commercially available phenolic curing agent can be used. For example, phenol and a phenol resin obtained by subjecting phenol to novolak can be used. Examples of the phenolic curing agent include monofunctional compounds such as phenol, o-cresol, m-cresol, and p-cresol; and bifunctional compounds such as catechol, resorcin, and hydroquinone; A trifunctional compound such as 2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene or 1,3,5-trihydroxybenzene. Further, as the curing agent, a phenol novolak resin obtained by varnishing these phenol-based curing agents with a methylene chain or the like can be used.

Specific examples of the phenol novolak resin include a resin obtained by subjecting one type of phenol compound to novolak, and is a cresol novolak resin, a catechol novolak resin, and a resorcinol novolak resin. a hydroquinone phenol varnish resin or the like; and a resin obtained by subjecting two or more phenol compounds to novolak, which is a catechol resorcinol novolak resin or a resorcinol pair. Hydroquinone novolac resin and the like.

When a phenol novolak resin is used as the phenolic curing agent, the phenol novolak resin preferably contains a novolak resin having a selected from the following general formulae (II-1) and (II-2). a structural unit represented by at least one of the group consisting of.

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

The alkyl group may be any of a linear chain, a branched chain, and a cyclic chain. The aryl group may be a structure containing a hetero atom in the aromatic ring. In this case, it is preferred that the total number of hetero atoms and carbon atoms is 6 to 12 heteroaryl groups. The alkylene group in the aralkyl group may be any of a linear chain, a branched chain, and a cyclic group. The aryl group in the aralkyl group may be a structure containing a hetero atom in the aromatic ring. In this case, it is preferred that the total number of hetero atoms and carbon atoms is 6 to 12 heteroaryl groups.

In the formula (II-1) and the formula (II-2), R ²¹ and R ²⁴ each independently represent an alkyl group, an aryl group or an aralkyl group. These alkyl groups, aryl groups and aralkyl groups may further have a substituent. The substituent may, for example, be an alkyl group (but not including R ²¹ and R ²⁴ is an alkyl group), an aromatic group, a halogen atom, a hydroxyl group or the like. M21 and m22 each independently represent an integer of 0 to 2. When m21 and m22 are 2, two R ²¹ and R ²⁴ may be the same or different. M21 and m22 are preferably each independently 0 or 1, more preferably 0. N21 and n22 are the number of structural units represented by the general formulae (II-1) and (II-2) contained in the phenol novolak resin, and each independently represents an integer of 1 to 7.

In the formula (II-1) and the 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, the aryl group and the aralkyl group represented by R ²² , R ²³ , R ²⁵ and R ²⁶ may further have a substituent. The substituent may, for example, be an alkyl group (but not including R ²² , R ²³ , R ²⁵ and R ²⁶ is an alkyl group), an aryl group, a halogen atom or a hydroxyl group.

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

The phenolic curing agent may contain one type of compound having a structural unit represented by the formula (II-1) or the formula (II-2) alone or in combination of two or more. It is preferably a case comprising at least one compound having a structural unit derived from resorcin represented by the above formula (II-1).

The compound having a structural unit represented by the general formula (II-1) may further contain at least one partial structure derived from a phenol compound other than resorcin. In the general formula (II-1), as a partial structure derived from a phenol compound other than resorcin, for example, a partial structure derived from a phenol compound of phenol, cresol or phthalic acid may be mentioned. Phenol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene. The partial structure derived from these phenol compounds may be contained alone or in combination of two or more. Further, the compound having a structural unit represented by the above formula (II-2) may further contain at least one partial structure derived from a phenol compound other than catechol. In the general formula (II-2), as a partial structure derived from a phenol compound other than catechol, for example, a partial structure derived from a phenol compound of phenol, cresol or m-phenylene is exemplified. Phenol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene. The partial structure derived from these phenol compounds may be contained alone or in combination of two or more.

Here, the partial structure derived from a phenol compound means a monovalent or divalent group composed of one or two hydrogen atoms removed from the benzene ring portion of the phenol compound. Further, the position at which the hydrogen atom is removed is not particularly limited.

Further, among the compounds having a structural unit represented by the general formula (II-1), the content of the partial structure derived from resorcin is not particularly limited. The content of the partial structure derived from resorcinol relative to the total mass of the compound having a structural unit represented by the general formula (II-1) is preferably 55 mass% or more, from the viewpoint of the elastic modulus. From the viewpoint of the glass transition temperature (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.

Further, the phenol novolak resin preferably contains a novolak resin having at least one pass selected from the group consisting of the following general formulae (III-1) to (III-4) Part of the structure represented by the formula.

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

In the formula (III-a) and the 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 represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

The curing agent having a partial structure represented by at least one of the general formulae (III-1) to (III-4) can be additionally produced by a production method described later, and the production method is The dihydric phenol compound is subjected to novolak.

The partial structure represented by the general formula (III-1) to the general formula (III-4) may be contained as a main chain skeleton of the compound or may be contained as a part of the branch. Further, each of the structural units constituting the partial structure represented by any one of the general formulae (III-1) to (III-4) may be contained at random or may be contained regularly. It is contained in a block shape. Further, in the general formulae (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.

In the details of each of the general formulae (III-1) to (III-4), a plurality of Ar ³¹ to Ar ³⁴ may be the same atomic group, or two or more kinds of atomic groups may be contained. Further, Ar ³¹ to Ar ³⁴ each independently represent a group represented by any one of the formula (III-a) and the formula (III-b).

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

R ³² and R ³³ in the formula (III-a) and the 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 a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tertiary butyl group, and a pentyl group. , hexyl, heptyl and octyl. Further, the substitution positions of R ³² and R ³³ in the formula (III-a) and the formula (III-b) are not particularly limited.

Ar ³¹ to Ar ³⁴ in the general formulae (III-a) to (III-b) are preferably selected from the group derived from dihydroxybenzene from the viewpoint of achieving more excellent thermal conductivity. In the formula (III-a), R ³¹ is a hydroxyl group and R ³² and R ³³ are a group of a hydrogen atom), and a group derived from dihydroxynaphthalene (in the formula (III-b), R ³⁴ is At least one of the groups of a hydroxyl group).

Here, the "dihydroxybenzene-derived group" means a binary group composed of two hydrogen atoms removed from the aromatic ring portion of the 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 viewpoints of productivity and fluidity of the epoxy resin composition, Ar ³¹ to Ar ^{34 are more} preferably each independently derived from a dihydroxybenzene group, and further preferably selected from the group consisting of 1, At least one of the group consisting of a group of 2-dihydroxybenzene (catechol) and a group derived from 1,3-dihydroxybenzene (resorcinol). In particular, from the viewpoint of particularly improving thermal conductivity, Ar ³¹ to Ar ³⁴ preferably contain at least a group derived from resorcin. Moreover, from the viewpoint of particularly improving thermal conductivity, the structural unit represented by n31 to n34 preferably contains a group derived from resorcin.

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

The ratio of mx and nx (x is any one of 31, 32, 33 or 34, and the x values of mx and nx are the same) in the general formulae (III-1) to (III-4), from the flow From the viewpoint of sex, it is preferably mx/nx = 20/1 to 1/5, more preferably 20/1 to 5/1, still more preferably 20/1 to 10/1. 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. Further, the lower limit of the total value of m and n is not particularly limited.

Mx and nx represent the number of structural units, indicating how much the corresponding structural unit is added to the molecule. Therefore, integer values are represented for a single molecule. Furthermore, mx and nx in (mx/nx) and (mx+nx), when it is a collection of a plurality of molecules, means that the average value is also a rational number.

a phenol novolak resin having a partial structure represented by at least one formula selected from the group consisting of the general formulae (III-1) to (III-4), especially when Ar ³¹ to Ar ³⁴ are When at least one of a substituted or unsubstituted dihydroxybenzene and a substituted or unsubstituted dihydroxynaphthalene is used, the phenol novolac resin is synthesized as compared with a phenolic resin which is only phenolic varnish. It is easier and has a tendency to obtain a hardener having a low melting point. Therefore, by including such a phenol resin as a curing agent, there is an advantage that the production and handling of the epoxy resin composition become easy. Further, whether the phenol novolak resin has a partial structure represented by any one of the general formulae (III-1) to (III-4), by field desorption mass spectrometry (FD-MS), Whether or not the fragment component contains a component corresponding to the partial structure represented by any one of the general formulae (III-1) to (III-4) can be judged.

The molecular weight of the phenol novolak resin having a partial structure represented by at least one formula selected from the group consisting of the general formulae (III-1) to (III-4) is not particularly limited. From the viewpoint of fluidity, the number average molecular weight (Mn) is preferably 2,000 or less, more preferably 1,500 or less, still more preferably 350 to 1,500. Further, the weight average molecular weight (Mw) is preferably 2,000 or less, more preferably 1,500 or less, still more preferably 400 to 1,500. Mn and Mw can be determined by a usual method using GPC (gel permeation chromatography).

The hydroxyl equivalent of the phenol novolak resin having a partial structure represented by at least one formula selected from the group consisting of the general formulae (III-1) to (III-4) is not particularly limited. The hydroxyl equivalent is preferably from 50 g/eq to 150 g/eq, more preferably from 50 g/eq to 120 g/eq, further preferably 55 g, from the viewpoint of crosslinking density contributing to heat resistance. /eq~120g/eq. In the present specification, the hydroxyl equivalent means a value measured in accordance with Japanese Industrial Standard JIS K0070:1992.

The phenol novolak resin may contain a phenol compound constituting a phenol novolak resin, that is, a monomer. The phenolic compound constituting the phenol novolak resin, that is, the content ratio of the monomer (hereinafter also referred to as "monomer content") is not particularly limited. The monomer content in the phenol novolak resin is preferably from 5% by mass to 80% by mass, more preferably from 15% by mass to 60% by mass, even more preferably from 20% by mass, from the viewpoint of thermal conductivity and moldability. % to 50% by mass.

When the monomer content is 80% by mass or less, since the monomer component which does not contribute to the crosslinking at the time of the hardening reaction is small, and the high molecular weight body which is crosslinked is increased, a higher-order structure having a higher density can be formed. And there is a tendency to increase the thermal conductivity. In addition, since the monomer content is 5% by mass or more, since it tends to flow during molding, there is a tendency that the adhesion to the inorganic filler can be further improved, and further excellent thermal conductivity and heat resistance can be achieved.

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

(Curing Agent) When a phenolic curing agent is used in the epoxy resin composition, a curing accelerator may be used in combination as needed. Further, the epoxy resin composition can be sufficiently cured by using a curing accelerator in combination. The type and content of the curing accelerator are not particularly limited, and a suitable curing accelerator can be selected from the viewpoints of the reaction rate, the reaction temperature, and the storage stability.

Specific examples thereof include an imidazole compound, a tertiary amine compound, an organic phosphine compound, and a complex of an organic phosphine compound and an organoboron compound. Among them, from the viewpoint of heat resistance, at least one selected from the group consisting of an organic phosphine compound and a complex of an organic phosphine compound and an organoboron compound is preferred.

Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl (p-toluene) phosphine, stilbene (alkyl phenyl) phosphine, ginseng (alkoxyphenyl) phosphine, and ginsyl (alkyl alkoxybenzene). Phosphine, ginseng (dialkyl phenyl) phosphine, ginseng (trialkyl phenyl) phosphine, stilbene (tetraalkyl phenyl) phosphine, quinone (dialkoxyphenyl) phosphine, ginseng (trialkoxyphenyl) phosphine, ginseng (Tetraalkoxyphenyl)phosphine, trialkylphosphine, dialkylarylphosphine, alkyldiarylphosphine, and the like.

Further, specific examples of the complex of the organic phosphine compound and the organoboron compound include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-toluateborate, tetrabutylphosphonium tetraphenylborate, and n-butyltriphenylbenzene. Tetraphenyl hydride borate, butyl triphenyl sulfonium tetraphenylborate, methyl tributyl hydrazine tetraphenyl borate, and the like. These hardening accelerators may be used alone or in combination of two or more.

When two or more kinds of curing accelerators are used in combination, the mixing ratio can be determined depending on the characteristics required for the semi-cured epoxy resin composition (for example, the degree of flexibility required), and is not particularly limited.

When the epoxy resin composition contains a hardening accelerator, the content of the hardening accelerator in the epoxy resin composition is not particularly limited. The content of the curing accelerator is preferably from 0.5% by mass to 1.5% by mass, more preferably from 0.5% by mass to 1% by mass, even more preferably from 0.5% by mass to 1% by mass based on the total mass of the epoxy compound and the curing agent. It is 0.6% by mass to 1% by mass.

(Inorganic Filler) The epoxy resin composition may contain at least one inorganic filler. The epoxy resin composition can achieve high thermal conductivity by including an inorganic filler. The inorganic filler material may be non-conductive or electrically conductive. By using a non-conductive inorganic filler, there is a tendency to reduce the risk of insulation degradation. Moreover, by using a conductive inorganic filler, there is a tendency to further improve thermal conductivity.

Specific examples of the non-conductive inorganic filler include alumina (alumina), magnesium oxide, aluminum nitride, boron nitride, tantalum nitride, cerium oxide (cerium oxide), and aluminum hydroxide. Barium sulfate and the like. Moreover, as a conductive inorganic filler, gold, silver, nickel, copper, etc. are mentioned. Among them, from the viewpoint of thermal conductivity, as the inorganic filler, it is preferably selected from the group consisting of alumina (alumina), boron nitride, magnesium oxide, aluminum nitride, and cerium oxide (cerium oxide). At least one of them is more preferably at least one selected from the group consisting of boron nitride and alumina (alumina). These inorganic fillers may be used alone or in combination of two or more.

The inorganic filler is preferably used by mixing two or more kinds of volume average particle diameters. By mixing two or more kinds of inorganic fillers having different volume average particle diameters from each other, the inorganic filler having a small particle diameter is packed in the voids of the inorganic filler having a large particle diameter, thereby using only a single The inorganic filler of the particle size can exhibit a higher thermal conductivity because the inorganic filler can be more densely packed. Specifically, when alumina is used as the inorganic filler, the inorganic filler can be most densely packed by using a ratio of a range of alumina having a volume average particle diameter of 16 μm to 20 μm. 60% by volume to 75% by volume, alumina having a volume average particle diameter of 2 μm to 4 μm is 10% by volume to 20% by volume, and alumina having a volume average particle diameter of 0.3 μm to 0.5 μm is 10% by volume to 20% by volume. Further, when boron nitride and aluminum oxide are used in combination as the inorganic filler, the inorganic filler can be made more thermally conductive by using a ratio of a volume having a volume average particle diameter of 20 μm to 100 μm. Boron is 60% by volume to 90% by volume, alumina having a volume average particle diameter of 2 μm to 4 μm is 5% by volume to 20% by volume, and alumina having a volume average particle diameter of 0.3 μm to 0.5 μm is 5% by volume to 20% by volume. %. The volume average particle diameter of the inorganic filler can be measured under normal conditions using a laser diffraction scattering particle size distribution device.

The volume average particle diameter (D ₅₀ ) of the inorganic filler can be measured by a laser diffraction scattering method. For example, the inorganic filler in the epoxy resin composition is extracted and measured using a laser diffraction scattering particle size distribution device (for example, Beckman Coulter, trade name LS230). Specifically, an inorganic filler component is extracted from the epoxy resin composition using an organic solvent, nitric acid, aqua regia, or the like, and sufficiently dispersed by an ultrasonic disperser or the like, and the weight cumulative particle size distribution curve of the dispersion is measured. The volume average particle diameter (D ₅₀ ) means a particle diameter which is accumulated to 50% from the small particle diameter side in the particle size distribution curve obtained by the above measurement.

The content of the inorganic filler in the epoxy resin composition is not particularly limited. Here, from the viewpoint of thermal conductivity, the content of the inorganic filler is preferably more than 50% by volume, more preferably more than 70% by volume, based on 100% by volume of the total volume of the total solid content of the epoxy resin composition. 90% by volume or less. If the content of the inorganic filler exceeds 50% by volume, a higher thermal conductivity can be achieved. On the other hand, when the content of the inorganic filler is 90% by volume or less, there is a tendency to suppress a decrease in flexibility of the epoxy resin composition and a decrease in insulation properties.

(Cane Coupling Agent) The epoxy resin composition may contain at least one decane coupling agent. The decane coupling agent is considered to have an effect of improving the insulation reliability by the action of forming a covalent bond between the surface of the inorganic filler and the resin surrounding it (equivalent In the binder), the increase in thermal conductivity and the infiltration of moisture.

The type of the decane coupling agent is not particularly limited, and a commercially available decane coupling agent can also be used. Considering the compatibility of the epoxy compound having a liquid crystal original skeleton with a hardener and the heat loss at the interface between the resin layer and the inorganic filler, in the present embodiment, it is suitable to use an epoxy at the end. a decane coupling agent of a group, an amine group, a thiol group, an amine ester group, and a hydroxyl group.

Specific examples of the decane coupling agent include 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropyltriethoxydecane, and 3-epoxypropoxypropylmethyl. Diethoxy decane, 3-glycidoxypropylmethyldimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-aminopropyltri Ethoxy decane, 3-(2-aminoethyl)aminopropyltrimethoxydecane, 3-(2-aminoethyl)aminopropyltrimethoxydecane, 3-aminopropyltrimethoxydecane, 3 Phenylaminopropyltrimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltriethoxydecane, 3-aminoesterpropyltriethoxydecane, and the like. Further, a decane coupling agent oligomer (manufactured by Hitachi Chemical Techno Service Co., Ltd.) represented by the trade name SC-6000KS2 may be mentioned. These decane coupling agents may be used alone or in combination of two or more.

(Other components) The epoxy resin composition may contain other components in addition to the above components as needed. As other components, a solvent, an elastomer, a dispersing agent, and a precipitation inhibitor can be mentioned, for example. The solvent is not particularly limited as long as it does not interfere with the curing reaction of the epoxy resin composition, and an organic solvent which is usually used can be appropriately selected and used.

[Resin Sheet] The resin sheet of the present embodiment is a sheet-like formed body of an epoxy resin composition. The resin sheet can be formed by applying a varnish-like epoxy resin composition (hereinafter also referred to as "resin varnish") to the support to form a resin layer (epoxy resin composition layer), and then drying the resin layer. It is produced by removing at least a part of an organic solvent, and the varnish-like epoxy resin composition is prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition. Examples of the support include a release film such as a PET (polyethylene terephthalate) film.

The application of the resin varnish can be carried out by a known method. Specifically, it can be carried out by a method such as comma coating, die coating, lip coating, or gravure coating. As a method of forming the epoxy resin composition layer of a specific thickness, a coating method of applying a resin varnish that adjusts a flow rate from a nozzle by passing a coating object through a gap between the gaps is mentioned. Bufa and so on. For example, when the thickness of the resin layer (epoxy resin composition layer) before drying is 50 μm to 500 μm, a doctor blade coating method is preferably used.

The drying method is not particularly limited as long as it can remove at least a part of the organic solvent contained in the resin varnish, and can be appropriately selected depending on the drying method generally used and the organic solvent contained in the resin varnish. In general, a method of performing heat treatment at about 80 to 150 ° C is exemplified.

The density of the resin sheet is not particularly limited, and can be, for example, 3 g/cm ² to 3.4 g/cm ² . In view of the flexibility and thermal conductivity of the resin sheet, it is preferably from 3 g/cm ² to 3.3 g/cm ² , more preferably from 3.1 g/cm ² to 3.3 g/cm ² . The density of the resin sheet can be adjusted, for example, by the amount of the inorganic filler.

The thickness of the resin sheet is not particularly limited and can be appropriately selected depending on 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 viewpoint of thermal conductivity, electrical insulation, and sheet flexibility.

The resin sheet (epoxy resin composition layer) hardly undergoes a hardening reaction. Therefore, although it has flexibility, it lacks flexibility as a sheet. Therefore, the state in which the support such as the PET film is removed may lack self-standing property and may be difficult to handle. Therefore, it is preferable that the resin sheet is subjected to semi-hardening treatment of the epoxy resin composition constituting the resin sheet. The resin sheet is in a semi-hardened state (B-stage state) in the epoxy resin composition layer, and is preferably a B-stage sheet which is further subjected to heat treatment.

[B-stage sheet] The B-stage sheet of the present embodiment is a sheet-like semi-cured material of an epoxy resin composition. The B-stage sheet can be produced, for example, by a production method including a step of heat-treating the resin sheet to a B-stage state. The heat treatment to form the resin sheet is excellent in thermal conductivity and electrical insulation, and is excellent in flexibility and service life as a B-stage sheet. The B-stage sheet in the present embodiment means a resin sheet formed of the following epoxy resin composition, and the viscosity of the epoxy resin composition is 10 ⁴ Pa ‧ s to 10 at normal temperature (25 ° C) ⁵ Pa‧s and 10 ² Pa‧s to 10 ³ Pa‧s at 100 °C. Further, the cured epoxy resin composition layer does not melt even when heated. Further, the viscosity can be measured by dynamic viscoelasticity measurement (frequency 1 Hz, load weight 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-hardened to the B-stage state, and can be appropriately selected depending on the configuration of the epoxy resin composition. The heat treatment is preferably carried out by a method selected from the group consisting of thermal vacuum pressing, hot roll lamination, and the like for the purpose of reducing voids (pores) generated in the resin layer when the resin varnish is applied. Thereby, the B-stage sheet having a flat surface can be efficiently produced. Specifically, for example, heating and pressurization are carried out under the conditions of a pressure of 80 ° C to 130 ° C, 1 second to 30 seconds, and 1 MPa to 30 MPa under reduced pressure (for example, 1 kPa), whereby it is possible to The epoxy resin composition is semi-hardened to a B-stage state.

The thickness of the B-stage sheet can be appropriately selected depending on the purpose. For example, it can be 50 μm to 350 μm, and is preferably 60 μm to 300 μm from the viewpoint of thermal conductivity, electrical insulation, and flexibility. Moreover, a resin sheet having an epoxy resin composition layer can be produced by heat-pressing while laminating two or more resin sheets.

<Semi-hardened epoxy resin composition> The semi-hardened epoxy resin composition of the present embodiment is a semi-cured material of an epoxy resin composition. The semi-hardened epoxy resin composition is derived from an epoxy resin composition and can be obtained by subjecting the epoxy resin composition to a semi-hardening treatment.

The semi-cured epoxy resin composition in the present embodiment means a semi-cured material of the following epoxy resin composition. When the epoxy resin composition is heated to 80 ° C to 120 ° C, the resin component is melted, and the viscosity is increased. Reduced to 10Pa‧s to 10 ⁴ Pa‧s. Further, even if the cured epoxy resin composition described later is heated, the resin component does not melt. Further, the viscosity can be measured by dynamic viscoelasticity measurement (frequency 1 Hz, load weight 40 g, temperature increase rate 3 ° C/min). The semi-hardening treatment can be carried out, for example, by heating the epoxy resin composition at a temperature of 50 to 180 ° C for 1 minute to 30 minutes.

[Hardified Epoxy Resin Composition] The cured epoxy resin composition of the present embodiment is a cured product of an epoxy resin composition. The cured epoxy resin composition of the present embodiment is obtained by using an epoxy resin composition and curing the epoxy resin composition. The cured epoxy resin composition of the present embodiment is excellent in thermal conductivity, and it is considered that the epoxy compound having a liquid crystal element in the molecule contained in the epoxy resin composition is formed into a smectic structure.

The hardened epoxy resin composition can be obtained by subjecting an uncured epoxy resin composition or a semi-hardened epoxy resin composition to a hardening treatment. The method of the hardening treatment can be appropriately selected depending on the constitution of the epoxy resin composition, the purpose of curing the epoxy resin composition, and the like, and is preferably heated and pressurized. For example, the hardening ring can be obtained by heating the epoxy resin composition in an uncured state or a hardened state at 100 to 250 ° C for 1 hour to 10 hours, more preferably at 130 to 230 ° C for 1 hour to 8 hours. Oxygen resin composition.

[Metal foil with resin] The resin-attached metal foil of the present embodiment includes a metal foil and a semi-hardened resin composition layer derived from the epoxy resin composition and disposed on the metal foil. The semi-hardened resin composition layer derived from the epoxy resin composition is excellent in thermal conductivity and electrical insulation. The semi-hardened resin composition layer can be obtained by heat-treating the epoxy resin composition to a B-stage state.

The metal foil is not particularly limited, and examples thereof include a gold foil, a copper foil, and an aluminum foil. Generally, a copper foil can be used. The thickness of the metal foil is, for example, 1 μm to 35 μm, and preferably 20 μm or less from the viewpoint of flexibility. Further, as the metal foil, a composite foil having a three-layer structure or a composite foil having a two-layer structure can be used; the composite foil of the three-layer structure is formed by providing a metal layer on both sides of a composite foil having a three-layer structure, and the three layers The composite foil of the structure is made of nickel, nickel phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy or the like as an intermediate layer, and copper foil is provided on both sides of the intermediate layer; the composite of the two-layer structure The foil is a composite of aluminum and copper foil. For the composite foil having a three-layer structure in which copper foil is provided on both sides of the intermediate layer, it is preferable to set the thickness of one of the copper layers to 0.5 μm to 15 μm and the thickness of the other copper layer to 10 μm. ~300μm.

A metal foil to which a resin is attached can be formed, for example, by coating an epoxy resin composition (preferably, a resin varnish) on a metal foil to form a resin layer (resin sheet), and a resin layer (resin sheet) The heat treatment is performed to produce a B-stage state. The method of forming the resin layer is as described above.

The production conditions of the resin-attached metal foil are not particularly limited, and it is preferred that the organic solvent used in the resin varnish is volatilized by 80% by mass or more in the resin foil after drying. The drying temperature is not particularly limited, but is preferably about 80 to 180 °C. The drying time can be appropriately selected in accordance with the gelation time of the resin varnish. The coating 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 in a B-stage state by further heat treatment. The conditions for heat-treating the resin composition are the same as those for the B-stage heat treatment.

[Metal substrate] The metal substrate of the present embodiment includes, in order, a metal support, a cured epoxy resin composition layer derived from an epoxy resin composition, and disposed on a metal support; and a metal foil, It is disposed on the hardened epoxy composition layer. The epoxy resin composition layer containing the epoxy resin composition disposed between the metal support and the metal foil is heat-treated in a hardened state, and is excellent in adhesion, thermal conductivity, and electrical insulation. .

The metal support can be appropriately selected depending on the purpose, its material, thickness, and the like. Specifically, a metal such as aluminum or iron can be used, and the thickness is set to 0.5 mm to 5 mm.

The metal foil disposed on the hardened resin composition layer has the same definition as 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 produced, for example, by the following means. On the metal support such as aluminum, the epoxy resin composition is applied and dried in the same manner as described above to form a resin layer, and further, a metal foil is placed on the resin layer, and heated and pressurized. It can be manufactured by hardening a resin layer. Further, the resin-coated metal foil is bonded to the metal support so as to face the metal support, and is heated and pressurized to be cured by curing the resin layer. [Examples]

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

Hereinafter, a material used for the production of the epoxy resin composition and an abbreviation thereof will be described. (Epoxy compound A (resin A) having a liquid crystal original skeleton) ‧4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropane Oxy) benzoate [epoxy equivalent: 212 g/eq; manufactured by the method described in JP-A-2011-74366]

(Epoxy compound B (resin B) having a liquid crystal original skeleton) ‧4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropane Oxy)-3-methylbenzoate [epoxy equivalent: 219 g/eq; manufactured by the method described in JP-A-2011-74366]

(Other epoxy compounds having a liquid crystal original skeleton) ‧YL6121H [biphenyl type epoxy compound; manufactured by Mitsubishi Chemical Corporation; epoxy equivalent: 172g/eq]

(Epoxy compound having no liquid crystal original skeleton) ‧828EL [Liquid bisphenol A type epoxy compound; manufactured by Mitsubishi Chemical Corporation; epoxy equivalent: 186g/eq]

(Inorganic filler material) ‧AA-3 [alumina particles; manufactured by Sumitomo Chemical Co., Ltd.; D ₅₀ : 3 μm] ‧ AA-04 [alumina particles; manufactured by Sumitomo Chemical Co., Ltd.; D ₅₀ : 0.40 μm] ‧ HP -40 [boron nitride particles; manufactured by Mizushima Alloy Iron Co., Ltd.; D ₅₀ : 40 μm]

(hardener) ‧CRN[catechol resorcinol novolac (mixing ratio based on mass: catechol / resorcin = 5/95) resin; containing 50% by mass of cyclohexanone ]

<Synthesis method of CRN> 627 g of resorcin, 33 g of catechol, 316.2 g of a 37% by mass aqueous formaldehyde solution, and 15 g of oxalic acid were placed in a separate flask equipped with a stirrer, a cooler and a thermometer. 300 g of water was heated to 100 ° C while heating in an oil bath. The reflux was carried out at about 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 the water. The reaction was continued at 170 ° C for 8 hours. After the reaction, concentration was carried out under reduced pressure for 20 minutes to remove water or the like in the system to obtain a target substance, that is, a phenol novolak resin CRN. In addition, when the structure of the obtained CRN was confirmed by FD-MS (Field Desorption Mass Spectrometer), it was confirmed that all the partial structures represented by the general formulae (III-1) to (III-4) were present. .

Further, it is considered that, in the above reaction conditions, a compound having a partial structure represented by the general formula (III-1) is initially formed, and then, by further dehydration reaction, a compound having a general formula (III-2) is produced. A compound having a partial structure represented by at least one formula represented by the formula (III-4).

With respect to the obtained CRN, measurement of Mn (number average molecular weight) and Mw (weight average molecular weight) was carried out in the following manner. The measurement of Mn and Mw was carried out using a high-speed liquid chromatography (manufactured by Hitachi, Ltd.; trade name: L6000) and a data analysis device (manufactured by Shimadzu Corporation; trade name: C-R4A). For the GPC column for analysis, the column G2000HXL and G3000HXL (trade name) manufactured by TOSOH Co., Ltd. were used. The sample concentration was 0.2% by mass, and the moving phase was measured using tetrahydrofuran at a flow rate of 1.0 mL/min. A polystyrene standard sample was used to prepare a calibration curve, and then this calibration curve was used to calculate Mn and Mw in terms of polystyrene.

Regarding the obtained CRN, the measurement of the hydroxyl equivalent was carried out in the following manner. The hydroxyl equivalent is determined by titration with ethyl acetate-potassium hydroxide. Further, since the color of the solution is dark, the judgment of the end point of the titration is not performed by the coloring method of the indicator, but by potentiometric titration. Specifically, it is a method in which the hydroxyl group of the measurement resin is subjected to chlorination in a pyridine solution, and then the excess reagent is decomposed with water, and then the produced acetic acid is titrated with a potassium hydroxide/methanol solution.

The obtained CRN is a novolac resin comprising a hardener (hydroxy equivalent: 62 g/eq, number average molecular weight 422, weight average molecular weight 564); the hardener is a mixture of the following compounds having a general formula ( a partial structure represented by at least one of the formulae (III-1) to (III-4), wherein Ar is a group: R ³¹ in the formula (III-a) is a hydroxyl group, and R ³² and R ³³ is a hydrogen atom, that is, a group derived from 1,2-dihydroxybenzene (catechol) and a group derived from 1,3-dihydroxybenzene (resorcinol), and the hardener contains 35 mass% as a monomer component of a low molecular diluent (resorcinol).

(hardening accelerator) ‧ TPP: triphenylphosphine [manufactured by Wako Pure Chemical Industries Co., Ltd.; trade name]

(Additive) ‧KBM-573: 3-Phenylaminopropyltrimethoxydecane [decane coupling agent; manufactured by Shin-Etsu Chemical Co., Ltd.; trade name]

(solvent) ‧CHN: cyclohexanone

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

(Example 1) <Preparation of epoxy resin composition> The epoxy resin 1 was obtained by mixing the resin A and YL6121H which are epoxy compounds having a liquid crystal original skeleton so that the epoxy equivalent was 9:1. When the compatibility was confirmed by the method described later, the epoxy mixture 1 had compatibility at a curing temperature of the epoxy resin composition of 140 ° C.

The following components were mixed to obtain an epoxy resin varnish 1 as an epoxy resin composition containing a solvent: 8.94% by mass of the epoxy mixture 1; 5.13% by mass of CRN as a curing agent; and 0.09% by mass as a curing accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.76% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of YL6121H) and the hardener (CRN) was set to 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 was applied onto a PET film by an applicator so as to have a thickness of 200 μm after drying, and then allowed to stand at room temperature (20 ° C). Dry at ~30 ° C for 5 minutes and further dry at 130 ° C for 5 minutes. Thereafter, hot pressurization (pressurization temperature: 150 ° C; vacuum degree: 1 kPa; press pressure: 15 MPa; pressurization time: 1 minute) was carried out in a vacuum presser to obtain a B-stage epoxy resin composition.

<Preparation of hardened epoxy resin composition with copper foil> After peeling off the PET film of the B-stage epoxy resin composition obtained by the above method, two copper foils were used, and the frosted surfaces of the copper foil were respectively The semi-hardened epoxy resin composition is sandwiched in a manner opposite to the semi-hardened resin composition, and vacuum thermocompression bonding is performed in a vacuum pressurizer (pressurization temperature: 180 ° C; vacuum degree: 1 kPa; press pressure: 15 MPa; Pressurization time: 6 minutes). Thereafter, the mixture was heated at 150 ° C for 2 hours under atmospheric pressure and heated at 210 ° C for 4 hours to obtain a cured epoxy resin composition 1 with copper foil.

<Evaluation> The epoxy mixture 1 and the cured epoxy resin composition 1 obtained as described above were evaluated in the following manner. The evaluation results are shown in Table 1.

(Measurement of Thermal Conductivity) The copper foil of the copper foil-cured epoxy resin composition 1 obtained above was etched and removed to obtain a sheet-like cured epoxy resin composition (resin cured product). The obtained resin sheet was cut into a length of 10 mm and a width of 10 mm to obtain a sample. After the sample was blackened in a graphite spray, the thermal diffusivity was evaluated using a 氙 flash method (manufactured by NETZSCH Co., Ltd.; trade name: LFA447 nanoflash). The value, the density measured by the Archimedes method, and the product of the specific heat measured by DSC (differential scanning calorimeter; manufactured by PerkinElmer; trade name: DSC Pyris1), The thermal conductivity of the cured resin sheet in the thickness direction was determined. The results are shown in Table 1.

(Confirmation of Formation of Layered Structure) The copper foil with the copper foil-cured epoxy resin composition 1 obtained above was etched and removed to obtain a sheet-like hardened epoxy resin composition (resin cured product) ). The obtained resin sheet was cut into a length of 10 mm and a width of 10 mm to obtain a sample. X-ray diffraction measurement (using an X-ray diffraction device manufactured by RIGAKU Co., Ltd.) using a CuK _α 1 ray in a range of a tube voltage of 40 kV, a tube current of 20 mA, and a diffraction angle of 2θ of 0.5 to 30° Whether or not a smectic structure is formed is determined by the presence or absence of a diffraction peak in a range of 1 to 10 degrees from 2θ.

(Confirmation of the liquid crystal phase) While the epoxy mixture 1 obtained above was heated, it was observed in a crossed polarized state using a polarizing microscope (manufactured by Olympus Co., Ltd.; product model: BS51) (magnification: 100 times) The state of the epoxy mixture 1 during heating changes. A phase transition from the crystal phase to the liquid crystal phase was observed at 120 ° C, which became a state in which the interference fringes due to the depolarized light were exhibited and the fluidity was obtained. Further, when the heating was further continued, a phase transition from the liquid crystal phase to the equilateral phase which was changed in the dark field was observed at 170 °C. The epoxy mixture 1 obtained as described above exhibits a liquid crystal phase at 120 ° C to 170 ° C.

(Measurement of Melting Point) The epoxy mixture 1 obtained above was measured using a differential scanning calorimeter DSC7 (manufactured by Perkin Elmer). Performing a differential scanning of a sample of 3 mg to 5 mg sealed in an aluminum pan at a temperature range of 25 ° C to 350 ° C in a nitrogen atmosphere at a temperature rise of 10 ° C / min and a flow rate of 20 ± 5 mL / min. The calorific value is measured, and the temperature at which the energy change is accompanied by the phase change (the temperature of the endothermic reaction peak) is taken as the melting point (phase transition temperature).

(Compatibility) The epoxy mixture 1 obtained above was heated to an isothermal phase transformation temperature or higher to be melted. After that, it was observed by a microscope (manufactured by Olympus Co., Ltd.; product model: BS51) while being naturally cooled, and the curing temperature of the epoxy resin composition was also the cured product at 140 ° C. status. No phase separation of the epoxy monomer mixture was observed. That is, it was confirmed that the epoxy mixture 1 has compatibility at a curing temperature of the epoxy resin composition, that is, 140 °C.

(Example 2) <Preparation of epoxy resin composition> The epoxy resin mixture 2 was obtained by mixing the resin A and YL6121H which are epoxy compounds having a liquid crystal original skeleton so that the epoxy equivalent was 8:2. When the compatibility was confirmed by the method described above, the epoxy mixture 2 had compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 2 as an epoxy resin composition containing a solvent: 8.90% by mass of the epoxy mixture 2; 5.21% by mass of CRN as a curing agent; and 0.09% by mass as a curing accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.72% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of YL6121H) and the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 2 and the cured epoxy resin composition 2 were produced 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 above. The results are shown in Table 1.

(Example 3) <Preparation of epoxy resin composition> The epoxy resin mixture 3 was obtained by mixing the resin A and the resin B which are epoxy compounds having a liquid crystal original skeleton so that the epoxy equivalent was 9:1. When the compatibility was confirmed by the method described above, the epoxy mixture 3 had compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 3 as a solvent-containing epoxy resin composition: 8.98 mass% of an epoxy mixture 3; 5.05 mass% of CRN as a hardener; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.80% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of the resin B) and the curing agent (CRN) was set to 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.

The B-stage epoxy resin composition 3 and the cured epoxy resin composition 3 were produced 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 above. The results are shown in Table 1.

(Example 4) <Preparation of epoxy resin composition> The epoxy resin mixture 4 was obtained by mixing the resin A and the resin B which are epoxy compounds having a liquid crystal original skeleton so that the epoxy equivalent was 7:3. When the compatibility is confirmed by the method described above, the epoxy mixture 4 has compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 4 as a solvent-containing epoxy resin composition: 8.98 mass% of an epoxy mixture 4; 5.05 mass% of CRN as a hardener; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.80% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of the resin B) and the curing agent (CRN) was set to 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.

The B-stage epoxy resin composition 4 and the cured epoxy resin composition 4 were produced 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 above. The results are shown in Table 1.

(Comparative Example 1) Resin A and YL6121H, which are epoxy compounds having a liquid crystal original skeleton, were mixed so that the epoxy equivalent was 7:3 to obtain an epoxy mixture 5. When the compatibility is confirmed by the method described above, the epoxy mixture 5 has compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 5 as a solvent-containing epoxy resin composition: 8.85 mass% of an epoxy mixture 5; 5.30 mass% of CRN as a hardener; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.68% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of YL6121H) and the hardener (CRN) was set to 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.

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

(Comparative Example 2) <Preparation of epoxy resin composition> Resin A and YL6121H which are epoxy compounds having a liquid crystal original skeleton were mixed so that the epoxy equivalent was 6:4 to obtain an epoxy mixture 6. When the compatibility was confirmed by the method described above, the epoxy mixture 6 had compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 6 as a solvent-containing epoxy resin composition: 8.81% by mass of an epoxy mixture 6; 5.39 mass% of CRN as a curing agent; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.63% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of YL6121H) and the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 6 and the cured epoxy resin composition 6 were produced 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 above. The results are shown in Table 2.

(Comparative Example 3) <Preparation of Epoxy Resin Composition> Resin A and YL6121H, which are epoxy compounds having a liquid crystal original skeleton, were mixed so that the epoxy equivalent was 5:5 to obtain an epoxy mixture 7. When the compatibility is confirmed by the method described above, the epoxy mixture 7 has compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 7 as a solvent-containing epoxy resin composition: 8.76 mass% of an epoxy mixture 7; 5.49 mass% of CRN as a hardener; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.58% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of YL6121H) and the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 7 and the cured epoxy resin composition 7 were produced 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 above. The results are shown in Table 2.

(Comparative Example 4) <Preparation of epoxy resin composition> A resin A having a liquid crystal original skeleton and 828EL as an epoxy compound having no liquid crystal primary skeleton were mixed so that the epoxy equivalent was 9:1. Epoxy mixture 8. When the compatibility is confirmed by the method described above, the epoxy mixture 8 has compatibility at a curing temperature of the epoxy resin composition of 140 °C.

The following components were mixed to obtain an epoxy resin varnish 8 as a solvent-containing epoxy resin composition: 8.96 mass% of an epoxy mixture 8; 5.10 mass% of CRN as a hardener; and 0.09 mass% as a hardening accelerator TPP; 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 mass% of KBM-573 as an additive; and 22.77% by mass as a solvent CHN.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A and The density of the mixture of 828EL) and the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 8 and the cured epoxy resin composition 8 were produced 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 above. The results are shown in Table 2.

(Comparative Example 5) <Preparation of epoxy resin composition> The following components were mixed to obtain an epoxy resin varnish 9 as a solvent-containing epoxy resin composition: 8.99% by mass of a resin having a liquid crystal original epoxy compound A; 5.04% by mass of CRN as a curing agent; 0.09% by mass of TPP as a hardening accelerator; 43.40% by mass of HP-40 as an inorganic filler, 9.81% by mass of AA-3, and 9.81% by mass of AA- 04; 0.06 mass% of KBM-573 as an additive; and 22.80 mass% of CHN as a solvent.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A) was used. The density of the mixture with the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 9 and the cured epoxy resin composition 9 were produced 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 above. The results are shown in Table 2.

(Comparative Example 6) <Preparation of epoxy resin composition> The following components were mixed to obtain an epoxy resin varnish 10 as a solvent-containing epoxy resin composition: 8.97 mass% of a resin as an epoxy compound having a liquid crystal source B; 5.08 mass% of CRN as a hardening agent; 0.09 mass% of TPP as a hardening accelerator; 43.40 mass% of HP-40 as an inorganic filler, 9.81 mass% of AA-3, and 9.81 mass% of AA- 04; 0.06 mass% of KBM-573 as an additive; and 22.78 mass% of CHN as a solvent.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (resin A) was used. The density of the mixture with the hardener (CRN) was set to 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.

The B-stage epoxy resin composition 10 and the cured epoxy resin composition 10 were produced 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 above. The results are shown in Table 2.

(Comparative Example 7) <Preparation of epoxy resin composition> The following components were mixed to obtain an epoxy resin varnish 11 as an epoxy resin composition containing a solvent: 8.50% by mass as another epoxy compound having a liquid crystal source YL6121H; 6.02% by mass of CRN as a hardening agent; 0.09% by mass of TPP as a hardening accelerator; 43.40% by mass of HP-40 as an inorganic filler, 9.81% by mass of AA-3, and 9.81% by mass of AA- 04; 0.06 mass% of KBM-573 as an additive; and 22.31 mass% of CHN as a solvent.

The density of boron nitride (HP-40) was set to 2.20 g/cm ³ , the density of alumina (AA-3 and AA-04) was set to 3.98 g/cm ³ , and the epoxy compound (YL6121H) was The density of the mixture of the hardener (CRN) was set to 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.

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

[Table 1]

[Table 2]

As shown in Tables 1 and 2, the thermal conductivity was the highest in Comparative Example 5 using only the resin A. When the resin A and YL6121H are used in combination, and the resin A and the resin B are used together, and the resins A and 828EL are used in combination as the epoxy compound, they are compatible with each other. Further, in the case where the resin A is used alone, the melting point is lowered by 10 ° C or more when the resin A and YL 6121H are used in combination or when the resin A and the resin B are used in combination. The thermal conductivity of the epoxy resin composition which is compatible with each other and formed with the smectic structure becomes higher than that of the epoxy resin composition in which the smectic structure is not formed. From this, it can be seen that a large difference in thermal conductivity is caused by the presence or absence of a smectic structure. According to the above technical content, it is possible to obtain an epoxy resin composition which has a low melting point and a high thermal conductivity.

The entire disclosure of Japanese Patent Application No. 2016-111371 is incorporated herein by reference. All of the documents, patent applications, and technical specifications described in the specification are incorporated by reference to the individual documents, patent applications, and technical specifications. Into this specification.

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Claims (13)

An epoxy resin composition containing two or more epoxy compounds having a liquid crystal original skeleton, a curing agent, and an inorganic filler; wherein the two or more epoxy compounds having a liquid crystal original skeleton are compatible with each other, and A smectic structure can be formed by reacting with the above-mentioned hardener. The epoxy resin composition according to claim 1, wherein the two or more epoxy compounds having a liquid crystal original skeleton include at least one compound represented by the following formula (I): In the formula (I), R ¹ to R ⁴ each independently represent 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 hardener comprises a phenol novolak resin. The epoxy resin composition according to any one of claims 1 to 3, wherein the hardener comprises a novolak resin having a selected from the group consisting of the following formula (II-1) and the following At least one structural unit represented by the general formula (II-2): In the general formula (II-1) and the general formula (II-2), R ²¹ and R ²⁴ each independently represent an alkyl group, an aryl group or an aralkyl group, and R ²² , R ²³ , R ²⁵ and R ²⁶ are each independently It represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, and m21 and m22 each independently represent an integer of 0 to 2, and n21 and n22 each independently represent an integer of 1 to 7. The epoxy resin composition according to any one of claims 1 to 3, wherein the curing agent comprises a novolac resin having a selected from the group consisting of the following formula (III-1) to the following A partial structure represented by at least one of the group consisting of the formula (III-4): In the general formulae (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer, and Ar ³¹ to Ar ³⁴ each independently represent the following general formula (III-a). Or any one of the groups represented by the following formula (III-b); In the formula (III-a) and the formula (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group, and R ³² and R ³³ each independently represent a hydrogen atom or an alkane having 1 to 8 carbon atoms. base. The epoxy resin composition according to any one of claims 1 to 5, wherein the curing agent contains a monomer as a phenol compound constituting the novolak resin, and the content of the monomer is in the hardener. It is 5 mass% to 80 mass%. The epoxy resin composition according to any one of claims 1 to 6, wherein the inorganic filler comprises a group selected from the group consisting of boron nitride, aluminum oxide, magnesium oxide, cerium oxide, and aluminum nitride. At least one of them. The epoxy resin composition according to any one of claims 1 to 7, wherein the inorganic filler has a content of more than 50% by volume in the solid content. A B-stage sheet which is a sheet-like semi-cured material of the epoxy resin composition according to any one of claims 1 to 8. A hardened epoxy resin composition which is a cured product of the epoxy resin composition according to any one of claims 1 to 8. A sheet-like molded article of the epoxy resin composition according to any one of claims 1 to 8, which is a resin sheet. A metal foil with a resin, comprising: a metal foil; and a semi-hardened epoxy resin composition layer, which is obtained from the epoxy resin composition according to any one of claims 1 to 8, and is disposed in On the aforementioned metal foil. A metal substrate, which is provided with a metal support, and a cured epoxy resin composition layer, which is obtained from the epoxy resin composition according to any one of claims 1 to 8, and is disposed on the metal support. And a metal foil disposed on the hardened epoxy resin composition layer.