WO2017145409A1

WO2017145409A1 - Epoxy resin molding material, molded product, molded cured product, and method for producing molded product

Info

Publication number: WO2017145409A1
Application number: PCT/JP2016/074878
Authority: WO
Inventors: 田中　賢治; 優香吉田; 慎一小杉; 片木　秀行; 陶　晴昭; 竹澤　由高
Original assignee: 日立化成株式会社
Priority date: 2016-02-25
Filing date: 2016-08-25
Publication date: 2017-08-31
Also published as: TW201800468A

Abstract

This epoxy resin molding material contains: an epoxy resin A that has a mesogen skeleton and a phase transition temperature of less than 140 °C; a curing agent; and an inorganic filling material.

Description

Epoxy resin molding material, molded product, molded cured product, and method for producing molded product

The present invention relates to an epoxy resin molding material, a molded product, a molded cured product, and a method for manufacturing the molded product.

Thermosetting resins such as epoxy resins are widely used as insulating materials used in industrial and automotive motors, inverters, and other devices from the standpoints of high insulation performance, ease of molding, heat resistance, etc. ing. In recent years, the high output and miniaturization of these devices have rapidly progressed, and the level of characteristics required for insulating materials has become considerably high. In particular, the amount of heat generated from a high-density conductor tends to increase with downsizing, and how to dissipate heat is an important issue. Accordingly, various attempts have been made to improve the thermal conductivity after molding of the thermosetting resin.

As a thermosetting resin having high thermal conductivity, an epoxy resin having a mesogen skeleton is used, and a cured product of a resin composition including the epoxy resin has been proposed (for example, see Patent Document 1). Epoxy resins having a mesogenic skeleton are disclosed in Patent Documents 2 to 4, for example. Moreover, as a thermosetting resin having high thermal conductivity and a low softening point (melting point), an epoxy resin having a specific structure as described in Patent Document 5 has been proposed.

Moreover, as one of the techniques for improving the thermal conductivity after molding of the thermosetting resin, there is a method of mixing a high thermal conductivity inorganic filler with the thermosetting resin to form a composite material (for example, Patent Documents). 6).

Japanese Patent No. 4118691 Japanese Patent No. 4619770 JP 2010-241797 A Japanese Patent No. 5471975 Japanese Patent No. 5127164 JP 2008-13759 A

When mixing an inorganic filler with a thermosetting resin, the viscosity of the resin composition increases as the amount of the inorganic filler increases, and workability tends to deteriorate, or the dispersibility of the inorganic filler tends to decrease. It is in. In addition, there is often a problem with the affinity between the organic thermosetting resin and the inorganic filler, and voids may occur at the interface between the thermosetting resin and the inorganic filler. For this reason, the thermal conductivity of the composite material may be lowered and the long-term reliability may be deteriorated.

Also, an epoxy resin having a mesogenic skeleton tends to have a high melting point due to the characteristics of the skeleton, which may cause a problem that fluidity is lowered and molding becomes difficult. As a countermeasure for this problem, a technique for increasing fluidity by adding a dispersant is generally known. However, in such a method, high thermal conductivity may not be exhibited after curing.

An object of the present invention is to provide an epoxy resin molding material that exhibits high thermal conductivity after curing, a molded product and a molded cured product using the epoxy resin molding material, and a method for producing the molded product.

The concrete means for achieving the above-mentioned problems are as follows.

<1> Epoxy resin A having a mesogenic skeleton and having a phase transition temperature of 140 ° C. or lower for transition from a crystal phase to a liquid crystal phase;
A curing agent;
An inorganic filler;
Epoxy resin molding material containing.

<2> The epoxy resin A is a reaction between a divalent phenol compound having two hydroxyl groups in one benzene ring and an epoxy resin B having a mesogenic skeleton and a phase transition from a crystal phase to a liquid crystal phase. The epoxy resin molding material as described in <1> containing a thing.

<3> The epoxy resin molding material according to <2>, wherein a phase transition temperature of the epoxy resin B is 140 ° C. or higher.

<4> The epoxy resin A is a ratio of the number of equivalents of the phenolic hydroxyl group of the divalent phenol compound to the number of equivalents of the epoxy group of the epoxy resin B (the number of equivalents of epoxy group / the number of equivalents of phenolic hydroxyl group). The epoxy resin molding material according to <2> or <3>, comprising a reaction product having a ratio of 100/10 to 100/20.

<5> The epoxy resin molding material according to any one of <2> to <4>, wherein the epoxy resin B includes a compound represented by the following general formula (I).

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

<6> The epoxy resin molding material according to any one of <2> to <5>, wherein the divalent phenol compound contains hydroquinone.

<7> The epoxy resin molding material according to any one of <1> to <6>, wherein the curing agent includes a phenol-based curing agent.

<8> The phenolic curing agent includes a compound having a structural unit represented by at least one selected from the group consisting of the following general formula (II-1) and the following general formula (II-2) <7 > Epoxy resin molding material.

In General Formula (II-1) and General Formula (II-2), each R ¹ independently represents an alkyl group, an aryl group, or an aralkyl group, and the alkyl group, aryl group, and aralkyl group each have a substituent. You may have. R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and the alkyl group, aryl group, and aralkyl group may have a substituent. Each m independently represents an integer of 0 to 2. Each n independently represents an integer of 1 to 7.

<9> The phenolic curing agent includes a compound having a structural unit represented by at least one selected from the group consisting of the following general formula (III-1) to general formula (III-4) <7 > Or <8> The epoxy resin molding material.

In the general formulas (III-1) to (III-4), m and n each independently represent a positive integer. Ar independently represents a group represented by the following general formula (III-a) or the following general formula (III-b).

In general formula (III-a) and general formula (III-b), R ¹¹ and R ¹⁴ each independently represents a hydrogen atom or a hydroxyl group. R ¹² and R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<10> The epoxy resin molding material according to any one of <1> to <9>, further including a silane coupling agent.

<11> The epoxy resin molding material according to <10>, wherein the silane coupling agent includes a silane coupling agent having a phenyl group.

<12> The epoxy resin molding material according to <11>, wherein the silane coupling agent having a phenyl group has a structure in which a phenyl group is directly bonded to a silicon atom.

<13> The adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler is 5.0 × 10 ⁻⁶ mol / m ² to 10.0 × 10 ⁻⁶ mol / m ² . The epoxy resin molding material according to any one of <10> to <12>.

<14> The epoxy resin molding material according to any one of <1> to <13>, wherein the inorganic filler includes at least one selected from the group consisting of magnesium oxide and alumina.

<15> The epoxy resin molding material according to any one of <1> to <14>, wherein the content of the inorganic filler is 60% by volume to 90% by volume in the solid content.

<16> The epoxy resin molding material according to any one of <1> to <15> in an A-stage state.

<17> The epoxy resin molding material according to <16>, wherein the mass reduction rate after heating at 180 ° C. for 1 hour is 0.1% by mass or less.

<18> A molded product obtained by molding the epoxy resin molding material according to any one of <1> to <17>.

<19> The molded article according to <18>, which has a diffraction peak in a range of diffraction angle 2θ of 3.0 ° to 3.5 ° in an X-ray diffraction spectrum obtained by an X-ray diffraction method using CuKα rays.

<20> A molded cured product obtained by curing the molded product according to <18> or <19>.

<21> The molded cured product according to <20>, wherein the molded product is cured by heating.

<22> In the X-ray diffraction spectrum obtained by the X-ray diffraction method using CuKα rays, the diffraction angle 2θ has a diffraction peak in the range of 3.0 ° to 3.5 °, described in <20> or <21> Molded and cured product.

<23> The epoxy resin molding material containing the epoxy resin A according to any one of <1> to <17> is molded in a temperature range of not less than the phase transition temperature of the epoxy resin A and not more than 150 ° C. Manufacturing method of a molded product.

According to the present invention, it is possible to provide an epoxy resin molding material that exhibits high thermal conductivity after curing, a molded product and a molded cured product using the epoxy resin molding material, and a method for producing the molded product.

It is a figure which shows an example of the graph obtained by differential scanning calorific value (DSC) measurement. It is an X-ray diffraction spectrum of the molding hardened | cured material of Example 1 and Comparative Example 3.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.

In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. Good. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
Furthermore, in this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. means.
In addition, in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended purpose of the process is achieved. included.

<Epoxy resin molding material>
The epoxy resin molding material of the present embodiment includes an epoxy resin A having a mesogenic skeleton and having a phase transition temperature of 140 ° C. or lower that causes a phase transition from a crystal phase to a liquid crystal phase, a curing agent, and an inorganic filler. . The epoxy resin molding material of this embodiment may further contain other components as necessary.

According to the epoxy resin molding material of this embodiment, it becomes possible to exhibit high thermal conductivity after curing. The reason for this is not clear, but when the epoxy resin has a phase transition temperature of 140 ° C. or lower, the epoxy resin is likely to melt when the epoxy resin molding material is produced. This is considered to be because the bias is suppressed as a result of the generation of the liquid crystal phase.
Hereinafter, each component contained in the epoxy resin molding material of this embodiment will be described in detail.

-Epoxy resin-
The epoxy resin molding material contains an epoxy resin A having a mesogenic skeleton and a phase transition temperature of 140 ° C. or lower. Epoxy resins having a mesogenic skeleton are liable to form a higher order structure upon curing and tend to achieve higher thermal conductivity when a cured product of the epoxy resin molding material is produced.

In the present specification, the “mesogen skeleton” indicates a molecular structure that may exhibit liquid crystallinity. Specific examples include a biphenyl skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, a stilbene skeleton, and derivatives thereof. Epoxy resins having a mesogenic skeleton tend to form a higher order structure at the time of curing, and tend to achieve higher thermal conductivity when a cured product is produced.

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

The phase transition temperature of the epoxy resin A is 140 ° C. or lower, and preferably 135 ° C. or lower.

The phase transition temperature can be measured using a differential scanning calorimetry (DSC) measuring device (for example, Pyris 1 manufactured by PerkinElmer). Specifically, the differential scanning calorific value of a sample of 3 mg to 5 mg sealed in an aluminum pan under the conditions of a temperature rise rate of 20 ° C./min, a measurement temperature range of 25 ° C. to 350 ° C., and a flow rate of 20 ± 5 ml / min in a nitrogen atmosphere. It is measured as a temperature at which an energy change (endothermic reaction) occurs with a phase transition. An example of a graph obtained by this measurement is shown in FIG. The temperature of the endothermic reaction peak appearing in FIG. 1 is defined as a phase transition temperature.

The epoxy resin A is not particularly limited as long as it has a mesogenic skeleton and a phase transition temperature of 140 ° C. or lower. For example, the epoxy resin A may be an epoxy compound or an oligomer of an epoxy compound. The oligomer may be a reaction product of epoxy compounds, or may be in a prepolymer state in which a part of the epoxy compound is partially reacted with a curing agent or the like. The curing agent used for prepolymerization may be the same as or different from the curing agent contained in the epoxy resin composition. When a part of an epoxy compound having a mesogenic skeleton is polymerized, the moldability may be improved. The epoxy compound used for prepolymerization is preferably an epoxy resin B having a mesogenic skeleton and a property of phase transition from a crystal phase to a liquid crystal phase. Epoxy resin B may have a phase transition temperature of 140 ° C. or lower or may exceed 140 ° C.

In particular, when the phase transition temperature of the epoxy resin B exceeds 140 ° C., the epoxy resin B is a reaction product prepolymerized by reacting with a dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring. It is preferable to use it. It is preferable to use such a dihydric phenol compound from the viewpoint of controlling the molecular weight, thermal conductivity, and glass transition temperature (Tg) of the epoxy resin.
Moreover, when the epoxy resin B and the dihydric phenol compound are partially reacted to form a prepolymer, the phase transition temperature can be lowered. Therefore, even if the phase transition temperature of the epoxy resin B exceeds 140 ° C., it can be used. In general, since an epoxy resin having a mesogenic skeleton has a high phase transition temperature, a prepolymerization technique is useful.

When the phenol compound used for prepolymerization is a monohydric phenol compound having one hydroxyl group in one molecule, the crosslink density after curing is lowered, so that the thermal conductivity may be lowered. On the other hand, when the phenol compound used for prepolymerization has three or more hydroxyl groups in one molecule, the reaction is difficult to control during prepolymerization, which may cause gelation. In addition, when a dihydric phenol compound having two or more benzene rings is used, the structure of the epoxy resin becomes rigid, which is advantageous for increasing the thermal conductivity, but the softening point tends to increase and the handling property tends to decrease. (For example, see Japanese Patent No. 5019272)

In addition, as a compound made to react with the epoxy resin B, an amine compound may be used in addition to the divalent phenol compound. However, when an amine compound is used, secondary amine or tertiary amine is produced in the prepolymerized epoxy resin, so that the storage stability of the epoxy resin itself and the epoxy resin after blending the epoxy resin with a curing agent The storage stability of the molding material may be reduced.

Epoxy resin B may be used alone or in combination of two or more. Specific examples of the epoxy resin B are described in, for example, Japanese Patent No. 4118691. Although the specific example of the epoxy resin B is shown below, this invention is not limited to these.

Epoxy resins B include 1- (3-methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1- (3-methyl-4-oxiranyl Methoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -benzene, 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate, etc. . Among these epoxy resins, from the viewpoint of improving thermal conductivity, 1- (3-methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -benzene and 4- {4 It is preferable to use at least one selected from the group consisting of-(2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate.

Furthermore, from the viewpoint of improving the fluidity of the molding material, the epoxy resin B forms a nematic structure with low ordering alone when undergoing a phase transition from the crystal phase to the liquid crystal phase. An epoxy resin that forms a smectic structure is preferred. Examples of such a resin include compounds represented by the following general formula (I).

Among the compounds represented by the general formula (I), compounds represented by the following general formula (I-1) are preferable.

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

Examples of the divalent phenol compound having two hydroxyl groups in one benzene ring include catechol, resorcinol, hydroquinone, and derivatives thereof. Examples of the derivatives include compounds in which a benzene ring is substituted with an alkyl group having 1 to 8 carbon atoms. Among these dihydric phenol compounds, it is preferable to use hydroquinone from the viewpoint of improving thermal conductivity. Since hydroquinone has a structure in which two hydroxyl groups are substituted so as to have a para-position, the prepolymerized epoxy resin obtained by reacting with epoxy resin B has a linear structure. For this reason, it is considered that the stacking property of the molecule is high and a higher order structure is easily formed. A divalent phenol compound may be used individually by 1 type, and may use 2 or more types together.

When the epoxy resin A is a reaction product of the epoxy resin B and the dihydric phenol compound, the epoxy resin A dissolves, for example, the epoxy resin B, the dihydric phenol compound, and the reaction catalyst in a synthetic solvent and applies heat. It can be synthesized by stirring while stirring. It is possible to synthesize the epoxy resin A by melting and reacting the epoxy resin B and the dihydric phenol compound without using a synthesis solvent, but it must be heated to a temperature at which the epoxy resin melts. For this reason, from the viewpoint of safety, a synthesis method using a synthesis solvent is preferable.

When synthesizing a reaction product of epoxy resin B and dihydric phenol, the ratio of the number of equivalents of phenolic hydroxyl group of dihydric phenol compound to the number of equivalents of epoxy group of epoxy resin B (equivalent number of epoxy groups / phenol) The equivalent number of the functional hydroxyl group is preferably from 100/10 to 100/30, more preferably from 100/10 to 100/20, and even more preferably from 100/10 to 100/15.

The synthetic solvent is not particularly limited as long as the solvent can be heated to a temperature necessary for the reaction between the epoxy resin B and the dihydric phenol compound to proceed. Specific examples include cyclohexanone, cyclopentanone, ethyl lactate, propylene glycol monomethyl ether, N-methylpyrrolidone and the like.

The amount of the synthesis solvent is preferably an amount capable of dissolving all of the epoxy resin B, the dihydric phenol compound, and the curing catalyst at the reaction temperature. Although the solubility varies depending on the raw material type, solvent type, etc. before the reaction, the charged solid content concentration is preferably 20% by mass to 60% by mass. When the amount of such a synthesis solvent is used, the viscosity of the resin solution after synthesis tends to be in a preferable range.

The type of reaction catalyst is not particularly limited, and an appropriate one can be selected from the viewpoint of reaction rate, reaction temperature, storage stability, and the like. Specific examples of the reaction catalyst include imidazole compounds, organophosphorus compounds, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more. Among them, from the viewpoint of heat resistance, an organic phosphine compound; an organic phosphine compound with maleic anhydride, a quinone compound (1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2, 6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, etc.), diazophenylmethane, phenol resin, etc. A compound having intramolecular polarization formed by adding a compound having a π bond; and a complex of an organic phosphine compound and an organic boron compound (tetraphenylborate, tetra-p-tolylborate, tetra-n-butylborate, etc.); It is preferably at least one selected from the group consisting of

Examples of organic phosphine compounds include triphenylphosphine, diphenyl (p-tolyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, tris (dialkylphenyl) phosphine, tris (tri Alkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkylphosphine, dialkylarylphosphine, alkyldiarylphosphine, etc. Can be mentioned.

The amount of the reaction catalyst is not particularly limited. From the viewpoint of reaction rate and storage stability, it is preferably 0.1% by mass to 1.5% by mass, and preferably 0.2% by mass to 1% by mass with respect to the total mass of the epoxy resin B and the dihydric phenol compound. It is more preferable that

The reaction product of epoxy resin B and dihydric phenol can be synthesized using a glass flask if it is a small scale, and using a stainless steel synthesis pot if it is a large scale. A specific synthesis method is as follows, for example. First, the epoxy resin B is put into a flask or a synthesis kettle, a synthesis solvent is added, and the mixture is heated to the reaction temperature with an oil bath or a heating medium, and the epoxy resin B is dissolved. A dihydric phenol compound is added thereto, and after confirming that the compound is sufficiently dissolved in the synthesis solvent, a reaction catalyst is added to start the reaction. If the reaction solution is taken out after a predetermined time, a reaction product solution of epoxy resin B and dihydric phenol can be obtained. Further, if the synthesis solvent is distilled off under reduced pressure under a heating condition in a flask or a synthesis kettle, the reaction product of epoxy resin B and dihydric phenol becomes a solid at room temperature (for example, 25 ° C.). can get.

The reaction temperature is not limited as long as the reaction between the epoxy group and the phenolic hydroxyl group proceeds in the presence of the reaction catalyst, and is preferably in the range of 100 ° C. to 180 ° C., for example, in the range of 120 ° C. to 170 ° C. More preferred. By setting the reaction temperature to 100 ° C. or higher, the time until the reaction is completed tends to be shortened. On the other hand, when the reaction temperature is 180 ° C. or lower, gelation tends to be suppressed.

The epoxy equivalent of the epoxy resin A is preferably 130 g / eq to 500 g / eq, more preferably 135 g / eq to 400 g / eq, and still more preferably 140 g / eq to 300 g / eq. The epoxy equivalent is measured by a perchloric acid titration method according to JIS K7236: 2009.

-Curing agent-
The epoxy resin molding material contains a curing agent. As a hardening | curing agent, what is normally used in this field | area can be especially used without a restriction | limiting. Examples of the curing agent include acid anhydride curing agents, amine curing agents, phenol curing agents, polyaddition curing agents such as mercaptan curing agents, and other latent curing agents such as imidazole. From the viewpoint of heat resistance and adhesion, an amine-based curing agent or a phenol-based curing agent is preferable. Furthermore, from the viewpoint of storage stability, a phenolic curing agent is more preferable.

As the phenolic curing agent, those usually used can be used without particular limitation. For example, a phenol compound and a phenol resin obtained by novolacizing a phenol compound can be used.

Examples of the phenol compound include monofunctional phenol compounds such as phenol, o-cresol, m-cresol, and p-cresol; bifunctional phenol compounds such as catechol, resorcinol, and hydroquinone; 1,2,3-trihydroxybenzene, 1 , 2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene and other trifunctional phenol compounds; Moreover, as a phenol resin, the phenol novolak resin which connected these phenol compounds with the methylene chain etc. and was novolak-ized is mentioned.

From the viewpoint of thermal conductivity, the phenolic curing agent is preferably a bifunctional phenolic compound such as catechol, resorcinol, hydroquinone, or the like, or a phenol novolac resin in which a bifunctional phenolic compound is linked by a methylene chain, From this point of view, a phenol novolac resin in which a bifunctional phenol compound is linked by a methylene chain is more preferable.

As the phenol novolak resin, a resin obtained by novolacizing one kind of phenol compound such as cresol novolak resin, catechol novolak resin, resorcinol novolak resin, hydroquinone novolak resin, or the like; A resin obtained by converting the compound into a novolak form.

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

In general formula (II-1) and general formula (II-2), each R ¹ independently represents an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group and aralkyl group represented by R ¹ may further have a substituent. Examples of the substituent include an alkyl group (except when R ¹ is an alkyl group), an aryl group, a halogen atom, and a hydroxyl group. m independently represents an integer of 0 to 2, and when m is 2, two R ^{1 s} may be the same or different. Each m is independently preferably 0 or 1, and more preferably 0. Each n independently represents an integer of 1 to 7.

In general formula (II-1) and general formula (II-2), R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group, and aralkyl group represented by R ² and R ³ may further have a substituent. Examples of the substituent include an alkyl group (except when R ² or R ³ is an alkyl group), an aryl group, a halogen atom, a hydroxyl group and the like.

R ² and R ^{3 in the} general formulas (II-1) and (II-2) are preferably a hydrogen atom, an alkyl group, or an aryl group from the viewpoint of storage stability and thermal conductivity. An atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 12 carbon atoms is more preferable, and a hydrogen atom is still more preferable.

In the compound having the structural unit represented by the general formula (II-1), the partial structure derived from a phenol compound other than resorcinol includes phenol, cresol, catechol, hydroquinone, 1 from the viewpoint of thermal conductivity and adhesiveness. , 2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene, preferably a partial structure derived from at least one selected from the group consisting of catechol and It is more preferably a partial structure derived from at least one selected from hydroquinone.

In the compound having the structural unit represented by the general formula (II-2), the partial structure derived from a phenol compound other than catechol includes phenol, cresol, resorcinol, hydroquinone, 1 from the viewpoint of thermal conductivity and adhesiveness. , 2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene, preferably a partial structure derived from at least one selected from the group consisting of resorcinol and It is more preferably a partial structure derived from at least one selected from hydroquinone.

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

In the compound having the structural unit represented by the general formula (II-1), the content ratio of the partial structure derived from resorcinol is not particularly limited. From the viewpoint of elastic modulus, the content ratio of the partial structure derived from resorcinol to the total mass of the compound having the structural unit represented by the general formula (II-1) is preferably 55% by mass or more. From the viewpoint of the transition temperature (Tg) and the linear expansion coefficient, it is more preferably 60% by mass or more, further preferably 80% by mass or more, and from the viewpoint of thermal conductivity, it is 90% by mass or more. Particularly preferred.

In the compound having the structural unit represented by the general formula (II-2), the content ratio of the partial structure derived from catechol is not particularly limited. From the viewpoint of elastic modulus, the content ratio of the partial structure derived from catechol to the total mass of the compound having the structural unit represented by the general formula (II-2) is preferably 55% by mass or more. From the viewpoint of the transition temperature (Tg) and the linear expansion coefficient, it is more preferably 60% by mass or more, further preferably 80% by mass or more, and from the viewpoint of thermal conductivity, it is 90% by mass or more. Particularly preferred.

The molecular weight of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is not particularly limited. From the viewpoint of fluidity, the number average molecular weight (Mn) is preferably 2000 or less, more preferably 1500 or less, and even more preferably 350 to 1500. Further, the weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and further preferably 400 to 1500. These Mn and Mw are measured by a usual method using gel permeation chromatography (GPC).

The hydroxyl equivalent of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is not particularly limited. From the viewpoint of the crosslinking density involved in heat resistance, the hydroxyl group equivalent is preferably 50 g / eq to 150 g / eq on average, more preferably 50 g / eq to 120 g / eq, and 55 g / eq to 120 g / eq. More preferably, it is eq. The hydroxyl equivalent is a value measured according to JIS K0070: 1992.

When a compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is used as the phenolic curing agent, it occupies the phenolic curing agent The proportion of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is preferably 50% by mass or more, and more preferably 80% by mass or more. More preferably, 90 mass% or more is still more preferable.

When a phenol novolac resin is used as the phenolic curing agent, the phenol novolak resin is represented by at least one selected from the group consisting of the following general formula (III-1) to the following general formula (III-4) It is also preferable to include a compound having

In the general formulas (III-1) to (III-4), m and n each independently represents a positive integer, and represents the number of each structural unit to which m or n is attached. Ar independently represents a group represented by the following general formula (III-a) or the following general formula (III-b).

A compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is produced as a by-product by a production method in which a divalent phenol compound is novolakized. Can be generated.

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

For each of the general formulas (III-1) to (III-4), a plurality of Ars may all be the same atomic group or may contain two or more types of atomic groups. Ar independently represents a group represented by general formula (III-a) or general formula (III-b).

R ¹¹ and R ¹⁴ in formulas (III-a) and (III-b) each independently represent a hydrogen atom or a hydroxyl group, and are preferably a hydroxyl group from the viewpoint of thermal conductivity. Further, the substitution positions of R ¹¹ and R ¹⁴ are not particularly limited.

In the general formula (III-a), R ¹² and R ¹³ each independently represents 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 ¹² and R ¹³ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, hexyl. Groups, heptyl groups, and octyl groups. Further, the substitution positions of R ¹² and R ¹³ in the general formula (III-a) are not particularly limited.

Ar in the general formulas (III-1) to (III-4) is a group derived from dihydroxybenzene (in the general formula (III-a), R ¹¹ is a hydroxyl group) from the viewpoint of achieving better thermal conductivity. a ^{is, R 12} and ^{R 13} is a hydrogen atom group), and at least one ^{of R 14} in group (general formula (III-b) derived from a dihydroxy naphthalene is selected from the group consisting of group) a hydroxyl group It is preferable that

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

Further, from the viewpoint of productivity and fluidity of the epoxy resin molding material, Ar is more preferably a group derived from dihydroxybenzene, and a group derived from 1,2-dihydroxybenzene (catechol) and 1,3- More preferably, it is at least one selected from the group consisting of groups derived from dihydroxybenzene (resorcinol). In particular, from the viewpoint of particularly improving thermal conductivity, it is preferable that Ar contains at least a group derived from resorcinol. Moreover, from the viewpoint of particularly improving the thermal conductivity, the structural unit represented by the structural unit n preferably contains a group derived from resorcinol.

When the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) includes a structural unit derived from resorcinol, the structural unit derived from resorcinol The content of is 55 in the total weight of the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) from the viewpoint of elastic modulus. Preferably from the viewpoint of Tg and linear expansion coefficient of the cured product, more preferably 60% by weight or more, still more preferably 80% by weight or more, from the viewpoint of thermal conductivity, It is particularly preferably 90% by mass or more.

In the general formulas (III-1) to (III-4), m and n are preferably m / n = 20/1 to 1/5 from the viewpoint of fluidity, and 20/1 to 5 / 1 is more preferable, and 20/1 to 10/1 is still more preferable. In addition, (m + n) is preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less from the viewpoint of fluidity. In addition, the lower limit of (m + n) is not particularly limited.

The compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is particularly a group derived from dihydroxybenzene in which Ar is substituted or unsubstituted, and When it is at least one kind of a group derived from substituted or unsubstituted dihydroxynaphthalene, compared with a phenolic resin or the like obtained by simply novolacizing these, a curing agent having a low softening point is easily synthesized. It tends to be obtained. Therefore, by including such a phenol resin as a curing agent, there are advantages such as easy manufacture and handling of the epoxy resin molding material.

Whether the phenol novolac resin has a partial structure represented by any one of the above general formulas (III-1) to (III-4) is determined by field desorption ionization mass spectrometry (FD-MS). Thus, it can be determined by whether or not the fragment component includes a component corresponding to the partial structure represented by any one of the above general formulas (III-1) to (III-4).

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

The hydroxyl equivalent of the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is not particularly limited. From the viewpoint of the crosslinking density involved in heat resistance, the hydroxyl group equivalent is preferably 50 g / eq to 150 g / eq on average, more preferably 50 g / eq to 120 g / eq, and 55 g / eq to 120 g / eq. More preferably, it is eq.

When a compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is used as the phenolic curing agent, The proportion of the compound having a structure represented by at least one selected from the group consisting of formula (III-1) to general formula (III-4) is preferably 50% by mass or more, more preferably 80% by mass or more. 90 mass% or more is more preferable.

A compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) as a phenol-based curing agent, or general formula (III-1) to general formula When a compound having a structure represented by at least one selected from the group consisting of (III-4) is used, the phenolic curing agent is selected from the general formula (II-1) and the general formula (II-2). A compound having a structural unit represented by at least one selected from the group consisting of: or a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4): The monomer which is a phenol compound which comprises the compound to have may be included. The content ratio of the monomer that is a phenol compound (hereinafter also referred to as “monomer content ratio”) is not particularly limited. From the viewpoint of thermal conductivity and moldability, the content in the phenolic curing agent is preferably 5% by mass to 80% by mass, more preferably 15% by mass to 60% by mass, and 20% by mass to 50% by mass. More preferably.

When the monomer content is 80% by mass or less, the amount of monomers that do not contribute to crosslinking during the curing reaction is reduced, and the number of crosslinked high molecular weight substances is increased, so that a higher density crosslinked structure is formed and the thermal conductivity is increased. Tend to improve. Moreover, since it is easy to flow at the time of shaping | molding because it is 5 mass% or more, it exists in the tendency for adhesiveness with a filler to improve more and to achieve the more excellent thermal conductivity and heat resistance.

The content of the curing agent is not particularly limited. For example, when a phenolic curing agent is used as the curing agent, the equivalent number of active hydrogens of the phenolic hydroxyl group contained in the phenolic curing agent (equivalent number of phenolic hydroxyl groups) and the equivalent of the epoxy group contained in the epoxy resin The number ratio (number of equivalents of phenolic hydroxyl group / number of equivalents of epoxy group) is preferably 0.5 to 2, more preferably 0.8 to 1.2.

-Inorganic filler-
The epoxy resin molding material contains at least one kind of inorganic filler. By including the inorganic filler, the cured product of the epoxy resin molding material has improved thermal conductivity. The inorganic filler is preferably insulating. In this specification, the “insulating property” of the inorganic filler means the property that the inorganic filler itself does not flow current even when a voltage of several hundred volts to several thousand volts is applied, and is the most occupied by electrons. This is because the valence band having a high energy level is separated from the next band (conduction band) above it by a large energy gap.

Specific examples of the material for the inorganic filler include boron nitride, alumina, silica, aluminum nitride, magnesium oxide, silicon oxide, aluminum hydroxide, and barium sulfate. Among these, at least one selected from the group consisting of magnesium oxide and alumina is preferable from the viewpoints of fluidity, thermal conductivity, and electrical insulation. Further, boron nitride, silica, aluminum nitride or the like may be further contained within a range not impeding fluidity.

The total proportion of at least one inorganic filler selected from the group consisting of magnesium oxide and alumina in the inorganic filler is preferably 50% by mass or more, more preferably 80% by mass or more, More preferably, it is 90 mass% or more.

The inorganic filler may have a single peak or a plurality of peaks when a particle size distribution curve is drawn with the particle diameter on the horizontal axis and the frequency on the vertical axis. By using an inorganic filler having a plurality of peaks in the particle size distribution curve, the filling property of the inorganic filler is improved, and the thermal conductivity of the epoxy resin molding material as a molded cured product is improved.

When the inorganic filler has a single peak when drawing the particle size distribution curve, the average particle size (D50) corresponding to 50% cumulative from the small particle size side of the weight cumulative particle size distribution of the inorganic filler is From the viewpoint of conductivity, the thickness is preferably 0.1 μm to 100 μm, more preferably 0.1 μm to 70 μm. The average particle size of the inorganic filler is measured using a laser diffraction method, and can be measured using a laser diffraction scattering particle size distribution measuring device (for example, LS230 manufactured by Beckman Coulter).

Further, the inorganic filler having a plurality of peaks in the particle size distribution curve can be constituted by combining two or more kinds of inorganic fillers having different average particle diameters, for example.

The content of the inorganic filler in the epoxy resin molding material is not particularly limited. From the viewpoint of thermal conductivity and moldability, when the total solid content of the epoxy resin molding material is 100% by volume, the content of the inorganic filler is preferably 60% by volume to 90% by volume, More preferably, it is 70 volume% to 85 volume%. Higher thermal conductivity can be achieved when the content of the inorganic filler is 60% by volume or more. On the other hand, when the content of the inorganic filler is 90% by volume or less, an epoxy resin molding material having excellent moldability can be obtained.

In the present specification, the solid content of the epoxy resin molding material means the remaining components obtained by removing volatile components from the epoxy resin molding material.

Let the content rate (volume%) of the inorganic filler in an epoxy resin molding material be the value calculated | required by following Formula.
Inorganic filler content (volume%) = {(Cw / Cd) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) + (Dw / Dd) + (Ew / Ed) + (Fw / Fd))} × 100

Here, each variable is as follows.
Aw: mass composition ratio of epoxy resin A (mass%)
Bw: mass composition ratio (% by mass) of curing agent
Cw: mass composition ratio of inorganic filler (mass%)
Dw: Mass composition ratio (% by mass) of a curing accelerator used as necessary
Ew: Mass composition ratio (% by mass) of a silane coupling agent used as necessary
Fw: mass composition ratio (% by mass) of other components used as necessary
Ad: Specific gravity of epoxy resin A Bd: Specific gravity of curing agent Cd: Specific gravity of inorganic filler Dd: Specific gravity of curing accelerator used as needed Ed: Specific gravity of silane coupling agent used as needed Fd: Necessary Specific gravity of other components used depending on

-Curing accelerator-
The epoxy resin molding material may contain a curing accelerator as necessary.
By using a curing accelerator together with the curing agent, the epoxy resin molding material can be further sufficiently cured. The type and blending amount of the curing accelerator are not particularly limited, and an appropriate one can be selected from the viewpoint of reaction rate, reaction temperature, storage property, and the like.

Specific examples of the curing accelerator include imidazole compounds, organophosphorus compounds, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more. Among them, from the viewpoint of heat resistance, an organic phosphine compound; an organic phosphine compound with maleic anhydride, a quinone compound (1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2, 6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, etc.), diazophenylmethane, phenol resin, etc. A compound having intramolecular polarization formed by adding a compound having a π bond; and a complex of an organic phosphine compound and an organic boron compound (tetraphenylborate, tetra-p-tolylborate, tetra-n-butylborate, etc.); It is preferably at least one selected from the group consisting of

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

When the epoxy resin molding material contains a curing accelerator, the content of the curing accelerator in the epoxy resin molding material is not particularly limited. From the viewpoint of fluidity and moldability, the content of the curing accelerator is preferably 0.1% by mass to 1.5% by mass with respect to the total mass of the epoxy resin and the curing agent, and is 0.2% by mass. More preferably, it is ˜1% by mass.

-Silane coupling agent-
The epoxy resin molding material may contain a silane coupling agent as required. By including a silane coupling agent, an interaction occurs between the surface of the inorganic filler and the epoxy resin surrounding it, improving fluidity, achieving high thermal conductivity, and further intruding moisture. Insulating reliability tends to improve insulation reliability.

The type of the silane coupling agent is not particularly limited, and one type may be used alone or two or more types may be used in combination. Among these, a silane coupling agent having a phenyl group is preferable. A silane coupling agent containing a phenyl group is likely to interact with an epoxy resin having a mesogenic skeleton. For this reason, when an epoxy resin molding material contains the silane coupling agent containing a phenyl group, when it is set as hardened | cured material, it exists in the tendency for the more excellent thermal conductivity to be achieved.

The type of silane coupling agent containing a phenyl group is not particularly limited. Specific examples of the silane coupling agent having a phenyl group include 3-phenylaminopropyltrimethoxysilane, 3-phenylaminopropyltriethoxysilane, N-methylanilinopropyltrimethoxysilane, and N-methylanilinopropyltriethoxy. Silane, 3-phenyliminopropyltrimethoxysilane, 3-phenyliminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, etc. Can be mentioned. The silane coupling agent containing a phenyl group may be used individually by 1 type, or may use 2 or more types together. A commercial product may be used as the silane coupling agent containing a phenyl group.

The proportion of the silane coupling agent having a phenyl group in the entire silane coupling agent is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. .

From the viewpoint of bringing the surface of the inorganic filler close to the epoxy resin surrounding the surface and achieving excellent thermal conductivity, it may contain a silane coupling agent in which a phenyl group is directly bonded to a silicon atom (Si). More preferred.

The proportion of the silane coupling agent in which the phenyl group is directly bonded to the silicon atom (Si) in the silane coupling agent having a phenyl group is preferably 30% by mass or more, and 50% by mass or more. Is more preferable, and it is still more preferable that it is 80 mass% or more.

When the epoxy resin molding material contains a silane coupling agent, the silane coupling agent may be present in a state of adhering to the surface of the inorganic filler or in a state of not adhering to the surface of the inorganic filler. , Both may be mixed.

When at least a part of the silane coupling agent is attached to the surface of the inorganic filler, the adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler is 5.0 × 10 ⁻⁶ mol. / M ² to 10.0 × 10 ⁻⁶ mol / m ² is preferable, and 5.5 × 10 ⁻⁶ mol / m ² to 9.5 × 10 ⁻⁶ mol / m ² is more preferable, and 6.0 × 10. ^{It is more} preferably ⁻⁶ mol / m ² to 9.0 × 10 ⁻⁶ mol / m ² .

The method for measuring the coating amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler is as follows.
First, the BET method is mainly applied as a method for measuring the specific surface area of the inorganic filler. The BET method is a gas adsorption method in which inert gas molecules such as nitrogen (N ₂ ), argon (Ar), and krypton (Kr) are adsorbed on solid particles, and the specific surface area of the solid particles is measured from the amount of adsorbed gas molecules. Is the law. The specific surface area can be measured using a specific surface area pore distribution measuring apparatus (for example, SA3100, manufactured by Beckman Coulter, Inc.).

Furthermore, silicon atoms derived from the silane coupling agent present on the surface of the inorganic filler are quantified. Examples of the quantitative method include ²⁹ Si CP / MAS (Cross-Polarization / Magic angle spinning) solid-state NMR (nuclear magnetic resonance). Since the nuclear magnetic resonance apparatus (for example, JNM-ECA700, manufactured by JEOL Ltd.) has high resolution, even when the epoxy resin molding material contains silica as an inorganic filler, the silicon atoms derived from silica as the inorganic filler and It is possible to distinguish from silicon atoms derived from silane coupling agents.
When the epoxy resin molding material does not contain silicon atoms other than silicon atoms derived from the silane coupling agent, the silicon atoms derived from the silane coupling agent are also quantified using a fluorescent X-ray analyzer (for example, Supermini 200, manufactured by Rigaku Corporation). can do.

Based on the specific surface area of the inorganic filler obtained as described above and the amount of silicon atoms derived from the silane coupling agent present on the surface of the inorganic filler, the silane coupling agent per specific surface area of the inorganic filler The coating amount of the derived silicon atoms is calculated.

In performing the above measurement, the inorganic filler contained in the epoxy resin molding material can be taken out of the epoxy resin molding material by, for example, the following method.
(1) An epoxy resin molding material is put in a magnetic crucible and heated in a muffle furnace or the like (for example, 600 ° C.) to burn the resin component.
(2) The resin component of the epoxy resin molding material is dissolved in an appropriate solvent, and the inorganic filler is recovered by filtration and dried.

When the epoxy resin molding material contains a silane coupling agent, the method for adding the silane coupling agent to the epoxy resin molding material is not particularly limited. Specifically, an integral method in which a silane coupling agent is also added when mixing other materials such as epoxy resin and inorganic filler, after mixing a certain amount of silane coupling agent with a small amount of resin, Master batch method to mix with other materials such as inorganic filler, before mixing with other materials such as epoxy resin, mix inorganic filler and silane coupling agent in advance on the surface of inorganic filler There is a pretreatment method for treating a ring agent. As a pretreatment method, a dry method in which a stock solution or a solution of a silane coupling agent is dispersed together with an inorganic filler by high-speed stirring, the inorganic filler is slurried with a dilute solution of the silane coupling agent, or an inorganic filler is used. Examples include a wet method in which the surface of the inorganic filler is treated with a silane coupling agent by immersing the silane coupling agent.

-Other ingredients-
The epoxy resin molding material may contain other components in addition to the components described above. Other ingredients include oxidized and non-oxidized polyolefins, carnauba wax, montanic acid esters, montanic acid, stearic acid and other mold release agents, silicone oil, silicone rubber powder and other stress relieving agents, glass fiber and other reinforcements Materials. The other components may be used alone or in combination of two or more.

<Method for preparing epoxy resin molding material>
The method for preparing the epoxy resin molding material is not particularly limited. As a general method, there is a method in which components of a predetermined blending amount are sufficiently mixed by a mixer or the like, then melt-kneaded, cooled, and pulverized. The melt kneading can be performed with a kneader, a roll, an extruder or the like that has been heated to 70 ° C. to 140 ° C. in advance. Epoxy resin molding materials are easy to use if they are tableted with dimensions and masses that meet the molding conditions.

<State of epoxy resin molding material>
The epoxy resin molding material is preferably in an A-stage state. When the epoxy resin molding material is in the A-stage state, when the epoxy resin molding material is cured by heat treatment, the epoxy resin molding material is between the epoxy resin and the curing agent as compared with the case where the epoxy resin molding material is in the B-stage state. The amount of reaction heat generated during the curing reaction increases, and the curing reaction easily proceeds. In this specification, the definitions of the terms A-stage and B-stage are based on JIS K 6800: 1985.

Whether or not the epoxy resin molding material is in the A-stage state is determined according to the following criteria.
A certain amount of the epoxy resin molding material is put into an organic solvent (tetrahydrofuran, acetone, etc.) in which the epoxy resin contained in the epoxy resin molding material is soluble, and the inorganic filler remaining after a certain period of time is filtered off. To do. If the difference between the mass after drying of the residue obtained by filtration and the mass of ash after high-temperature treatment is within ± 0.5% by mass, it is judged that the epoxy resin molding material was in the A-stage state. Is done. The mass of ash is measured and calculated in accordance with JIS K 7250-1: 2006.
Alternatively, the reaction heat per fixed mass of the epoxy resin molding material that has been previously determined to be in the A-stage state is measured by a differential scanning calorimeter (DSC, for example, Pyris 1 manufactured by PerkinElmer) and used as a reference value. Thereafter, if the difference between the measured value of the reaction heat per fixed mass of the prepared epoxy resin molding material and the reference value is within ± 5%, it is determined that the A-stage state has been reached.

When the epoxy resin molding material is in the A-stage state, the mass reduction rate after heating the A-stage epoxy resin molding material at 180 ° C. for 1 hour is preferably 0.1% by mass or less. The mass reduction rate after heating the A-stage epoxy resin molding material at 180 ° C. for 1 hour is 0.1% by mass or less, which means that the A-stage epoxy resin molding material is a so-called “solventless type”. Means an epoxy resin molding material. When the epoxy resin molding material is a solventless type, it is possible to obtain a molded product of the epoxy resin molding material without going through a drying step, and the process for obtaining a molded product or a molded cured product can be simplified.

<Molded product and molded cured product>
The molded product of the present embodiment is produced by molding the epoxy resin molding material of the present embodiment. The molded cured product of the present embodiment is produced by heat-treating (post-curing) the molded product of the present embodiment.

The method for molding the epoxy resin molding material is not particularly limited, and can be selected from known press molding methods or the like according to the application. The transfer molding method is the most common, but a compression molding method or the like may be used. The mold temperature during molding is preferably not less than the phase transition temperature of epoxy resin A and not more than 150 ° C., more preferably not more than 140 ° C. When the temperature is higher than the phase transition temperature of the epoxy resin A, the epoxy resin A is sufficiently melted during molding to facilitate molding, and when the temperature is 150 ° C. or lower, the thermal conductivity of the molded product tends to be excellent.

Mold temperature during press molding is generally 150 ° C to 180 ° C from the viewpoint of fluidity, and at temperatures below 150 ° C, general epoxy resins are difficult to melt, so molding tends to be difficult There is. However, the epoxy resin molding material of this embodiment can be molded even at 150 ° C. or lower.

The molded product preferably has a diffraction peak in the range of diffraction angle 2θ of 3.0 ° to 3.5 ° in an X-ray diffraction spectrum obtained by an X-ray diffraction method using CuKα rays. A molded product having such a diffraction peak has a highly ordered smectic structure among higher order structures, and is excellent in thermal conductivity.

The details of the X-ray diffraction measurement using CuKα rays in this specification are as follows.
〔Measurement condition〕
Equipment used: X-ray diffractometer ATX-G for thin film structure evaluation (manufactured by Rigaku Corporation)
X-ray type: CuKα
Scanning mode: 2θ / ω
Output: 50kV, 300mA
S1 slit: width 0.2 mm, height: 10 mm
S2 slit: width 0.2 mm, height: 10 mm
RS slit: width 0.2mm, height: 10mm
Measurement range: 2θ = 2.0 ° to 4.5 °
Sampling width: 0.01 °

As the epoxy resin molding material, the molded product removed from the mold after molding may be used as it is, or may be used after being cured by heating in an oven or the like, if necessary.

The molded cured product is obtained by post-curing the molded product by heating. The heating conditions for the molded product can be appropriately selected according to the type and amount of the epoxy resin A, the curing agent and the like contained in the epoxy resin molding material. For example, the heating temperature of the molded product is preferably 130 ° C. to 200 ° C., more preferably 150 ° C. to 180 ° C. The heating time of the molded product is preferably 1 hour to 10 hours, more preferably 2 hours to 6 hours.

As with the molded product before post-curing, the molded cured product is diffracted in the X-ray diffraction spectrum obtained by the X-ray diffraction method using CuKα rays in a diffraction angle 2θ of 3.0 ° to 3.5 °. Has a peak. This indicates that the highly ordered smectic structure formed in the molded product is maintained after post-curing by heating, and a molded cured product having excellent thermal conductivity can be obtained.

The molded product and molded cured product of the epoxy resin molding material of the present embodiment can be used in fields such as a printed wiring board and a semiconductor element sealing material in addition to industrial and automotive motors and inverters.

Next, the present invention will be described with reference to examples, but the scope of the present invention is not limited to these examples.

<Preparation of epoxy resin molding material>
The following components were blended in parts by mass as shown in Tables 3 to 6 below, and roll kneading was carried out under conditions of a kneading temperature of 80 ° C. and a kneading time of 10 minutes. Example 1 to Example 10 and Comparative Example 1 to Comparative Example Ten epoxy resin molding materials were produced. In addition, the blank in a table | surface represents no mixing | blending.

The epoxy resin molding materials of Examples 1 to 10 and Comparative Examples 1 to 10 were all in the A-stage state.
Further, when the epoxy resin molding materials of Examples 1 to 10 and Comparative Examples 1 to 10 were heated at 180 ° C. for 1 hour, the mass reduction ratios were all 0.1% by mass or less.

The raw materials used and their abbreviations are shown below.
[Epoxy resin]
・ Epoxy resin 1
trans-4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate (epoxy resin represented by the following structure, see Japanese Patent No. 5471975, epoxy equivalent: 212g / eq)

・ Epoxy resin 2-6
A compound obtained by reacting the epoxy resin 1 represented by the above structure with hydroquinone in the amount shown below and partially prepolymerizing it.

In the table, Ep is the number of equivalents of the epoxy group of the epoxy resin 1, and Ph is the number of equivalents of the phenolic hydroxyl group of hydroquinone. A method for synthesizing the epoxy resins 2 to 6 will be described later.

・ Epoxy resin 7
YSLV-80XY without mesogen skeleton (bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent: 195 g / eq, liquid crystal phase is not shown and isotropically cured)

[Curing agent]
CRN (catechol resorcinol novolak resin, catechol (C) and resorcinol (R) charge mass ratio (C / R): 5/95)
A method for synthesizing CRN will be described later.

[Inorganic filler]
Pyroxuma 3350 (magnesium oxide, manufactured by Kyowa Chemical Industry Co., Ltd., average particle size 50 μm, specific surface area 0.1 m ² / g)
Pyroxuma 3320 (magnesium oxide, manufactured by Kyowa Chemical Industry Co., Ltd., average particle size 20 μm, specific surface area 0.2 m ² / g)
・ Starmag SL (magnesium oxide, manufactured by Kamijima Chemical Co., Ltd., average particle size 8 μm, specific surface area 1 m ² / g)
AL35-63 (Alumina, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average particle size 50 μm, specific surface area 0.1 m ² / g)
AL35-45 (Alumina, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average particle size 20 μm, specific surface area 0.2 m ² / g)
AX3-32 (alumina, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average particle size 4 μm, specific surface area 1 m ² / g)

[Silane coupling agent]
KBM-202SS (diphenyldimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 244)
· KBM-573 (3-phenylaminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 255)

[Curing accelerator]
・ TPP (triphenylphosphine, manufactured by Hokuko Chemical Co., Ltd.)

[Release agent]
・ Montanic acid ester (Licowax E, manufactured by Clariant Japan)

(Synthesis of epoxy resins 2-6 (prepolymerization))
In a 500 mL three-necked flask, 50 g (0.118 mol) of epoxy resin 1 was weighed, and 80 g of propylene glycol monomethyl ether was added thereto as a solvent. A cooling tube and a nitrogen introducing tube were installed in the three-necked flask, and a stirring blade was attached so as to be immersed in the solvent. This three-necked flask was immersed in a 120 ° C. oil bath, and stirring was started. After confirming that the epoxy resin 1 was dissolved and became a transparent solution after a few minutes, hydroquinone was added so that Ep / Ph was the above value, and 0.5 g of triphenylphosphine was further added. Heating was continued at an oil bath temperature of. After continuing the heating for 5 hours, propylene glycol monomethyl ether was distilled off from the reaction solution under reduced pressure, and the residue was cooled to room temperature (25 ° C.), whereby an epoxy resin 2 in which a part of the epoxy resin 1 was prepolymerized. ~ 6 were obtained.

The solid content of the epoxy resins 1 to 6 was measured by the heat loss method. The solid content is measured by measuring 1.0 g to 1.1 g of the sample in an aluminum cup and leaving it in a dryer set at a temperature of 180 ° C. for 30 minutes, and the measured amount before heating. Based on the following formula:

Solid content (%) = (Measured amount after standing for 30 minutes / Measured amount before heating) × 100

The number average molecular weights of the epoxy resins 1 to 6 were measured by gel permeation chromatography (GPC). The measurement was performed using a high performance liquid chromatography L6000 manufactured by Hitachi, Ltd. and a data analyzer C-R4A manufactured by Shimadzu Corporation. As analytical GPC columns, Tosoh Corporation G2000HXL and 3000HXL were used. The measurement was performed at a sample concentration of 0.2% by mass, tetrahydrofuran as the mobile phase, and a flow rate of 1.0 ml / min. A calibration curve was prepared using a polystyrene standard sample, and the number average molecular weight was calculated using the polystyrene conversion value.

The epoxy equivalents of epoxy resins 1 to 6 were measured by the perchloric acid titration method.

The phase transition temperatures of the epoxy resins 1 to 6 were measured using a differential scanning calorimetry (DSC) measuring device (Pyris 1 manufactured by PerkinElmer). DSC measurement of a 3 mg to 5 mg sample sealed in an aluminum pan was performed under the conditions of a nitrogen atmosphere with a temperature increase rate of 20 ° C./min, a measurement temperature range of 25 ° C. to 350 ° C., and a flow rate of 20 ± 5 ml / min. The temperature at which the accompanying energy change occurs (endothermic reaction peak temperature) was defined as the phase transition temperature. In FIG. 1, the graph obtained by the DSC measurement of the epoxy resins 1 and 3 is shown.

These measurement results are summarized in Table 2 below.

(Synthesis of CRN)
A 3 L separable flask equipped with a stirrer, a cooler, and a thermometer was charged with 627 g of resorcinol, 33 g of catechol, 316.2 g of 37% by mass formaldehyde, 15 g of oxalic acid, and 300 g of water, and heated while heating in an oil bath. The temperature was raised to ° C. The mixture was refluxed at around 104 ° C., and the reflux temperature was maintained for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while water was distilled off, and the temperature was maintained at 170 ° C. for 8 hours. After the reaction, concentration was performed under reduced pressure for 20 minutes, water in the system was removed, and a phenol resin (CRN) was obtained.

Further, when the structure of the obtained CRN was confirmed by FD-MS, the existence of all the partial structures represented by the general formulas (III-1) to (III-4) was confirmed.

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

The number average molecular weight and the weight average molecular weight of the obtained CRN were measured by GPC. The measurement was performed using a high performance liquid chromatography L6000 manufactured by Hitachi, Ltd. and a data analyzer C-R4A manufactured by Shimadzu Corporation. As analytical GPC columns, Tosoh Corporation G2000HXL and 3000HXL were used. The measurement was performed at a sample concentration of 0.2% by mass, tetrahydrofuran as the mobile phase, and a flow rate of 1.0 ml / min. A calibration curve was prepared using a polystyrene standard sample, and the number average molecular weight and the weight average molecular weight were calculated using the polystyrene conversion value.

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

The obtained CRN is a mixture of compounds having a partial structure represented by at least one of the general formulas (III-1) to (III-4), and Ar is represented by the general formula (III-a) R ¹¹ is a hydroxyl group, and R ¹² and R ¹³ are hydrogen atoms, a group derived from 1,2-dihydroxybenzene (catechol) and a group derived from 1,3-dihydroxybenzene (resorcinol), respectively. It was a phenol resin (hydroxyl equivalent 65 g / eq, number average molecular weight 422, weight average molecular weight 564) containing 35% by mass of a monomer component (resorcinol) as a molecular diluent.

(Measurement of adhesion amount of silicon atom derived from silane coupling agent)
With respect to the epoxy resin molding materials of Examples 1 to 10 and Comparative Examples 1 to 10, the adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler was measured by the following method.
First, the specific surface area of the inorganic filler was measured by the BET method using a specific surface area pore distribution measuring apparatus (SA3100, manufactured by Beckman Coulter). Next, quantification of silicon atoms derived from the silane coupling agent present on the surface of the inorganic filler was performed by ²⁹ Si CP / MAS solid-state NMR using a nuclear magnetic resonance apparatus (manufactured by JEOL Ltd., JNM-ECA700). . From the obtained value, the adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler was calculated. The inorganic filler was taken out by placing the epoxy resin molding material in a magnetic crucible and heating it to 600 ° C. in a muffle furnace to burn the resin component.

(Production of molded products and molded cured products)
The epoxy resin molding materials of Examples 1 to 10 and Comparative Examples 1 to 10 were molded by a transfer molding machine under the conditions of a molding pressure of 20 MPa and a molding temperature of 140 ° C. to 180 ° C. to obtain molded products. When the molded product was post-cured to obtain a molded cured product, the curing conditions were 180 ° C. and 5 hours. In the table, the “existence of post-curing” column is “Yes”, the evaluation target is a molded cured product, and the “no” is the evaluation target is a molded product (after-curing is not performed) "-" Indicates that the "moldability" is "No" and the subsequent evaluation was not performed.

(Measurement of flow distance)
Spiral flow was measured as an index indicating the fluidity of the epoxy resin molding material during molding. As a measuring method, an epoxy resin molding material was molded under the above-mentioned conditions using a spiral flow measuring mold according to EMMI-1-66, and a flow distance (cm) was obtained. In Tables 3 to 6, “moldability” is defined as “possible” when the epoxy resin molding material flows and filled in the mold, and “no” when the unfilled portion remains.

(Measurement of glass transition temperature (Tg))
The molded product or molded cured product is cut to produce a 5 mm × 50 mm × 3 mm rectangular parallelepiped, and using a three-point bending vibration test jig with a dynamic viscoelasticity measuring apparatus (RSA-G2 manufactured by TA Instruments), frequency: The dynamic viscoelasticity was measured in the temperature range of 40 ° C. to 300 ° C. under the conditions of 1 Hz and temperature rising rate: 5 ° C./min. The glass transition temperature (Tg) was defined as the temperature at the peak top portion in tan δ obtained from the ratio of the storage elastic modulus and loss elastic modulus obtained by the above method.

(Density measurement)
The molded product or the molded cured product was cut to produce a 10 mm square cube, and the density (g / cm ³ ) was measured by Archimedes method.

(Measurement of thermal conductivity)
The molded product or the molded cured product was cut to produce a 10 mm square cube and blackened with a graphite spray. Thereafter, the thermal diffusivity was evaluated by a xenon flash method (LFA447 nanoflash manufactured by NETZSCH). From the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (Pyris 1 manufactured by Perkin Elmer), the thermal conductivity of the molded product or molded cured product was determined.

(About X-ray diffraction method)
The X-ray diffraction of the molded product or the cured product thereof was measured using a wide-angle X-ray diffractometer (Rigaku ATX-G). A CuKα ray was used as the X-ray source, the tube voltage was 50 kV, the tube current was 300 mA, and the scanning speed was 1.0 ° / min. In FIG. 2, the X-ray-diffraction spectrum of the molding hardened | cured material of Example 1 and Comparative Example 3 is shown.
When a diffraction peak appears in a diffraction angle 2θ of 3.0 ° to 3.5 °, it indicates that a smectic structure is formed in the molded product or the cured product thereafter.

(Evaluation results)
The evaluation results are shown in Tables 3 to 6. In the table, those judged as “No” in “Moldability” were indicated by “−” because the evaluation could not be performed. The unit of raw material is part by mass.

In Examples 1 to 5 and Comparative Examples 1 to 5, magnesium oxide was used as the inorganic filler, and in Examples 6 to 10 and Comparative Examples 6 to 10, alumina was used.
Comparative Examples 1, 2, 6, and 7 using the epoxy resin 1 or 2 having a phase transition temperature of 140 ° C. or higher could not be molded. Next, in comparison with systems using the same inorganic filler, which can be molded, Examples 1 to 10 having a phase transition temperature of 140 ° C. or lower are comparative examples using an epoxy resin 7 having no mesogenic skeleton. Compared with 3 to 5 and 8 to 10, the thermal conductivity increased by 2 W / (m · K) to 3 W / (m · K). The examples except Examples 4 and 5 in which the press molding temperature exceeds 150 ° C. are X-ray diffraction methods using CuKα rays, and have diffraction peaks in the diffraction angle 2θ range of 3.0 ° to 3.5 °. It was confirmed that a smectic structure was formed. In the comparative example, a diffraction peak indicating the formation of a smectic structure could not be confirmed even when the press molding temperature was changed.

The disclosure of Japanese Patent Application No. 2016-034887 filed on February 25, 2016 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

An epoxy resin A having a mesogenic skeleton and having a phase transition temperature of 140 ° C. or lower for transition from a crystal phase to a liquid crystal phase;
A curing agent;
An inorganic filler;
Epoxy resin molding material containing.
The epoxy resin A includes a reaction product of a divalent phenol compound having two hydroxyl groups in one benzene ring and an epoxy resin B having a mesogenic skeleton and a phase transition from a crystal phase to a liquid crystal phase. The epoxy resin molding material according to claim 1.
The epoxy resin molding material according to claim 2, wherein the phase transition temperature of the epoxy resin B is 140 ° C or higher.
The epoxy resin A has a ratio of the number of equivalents of the phenolic hydroxyl group of the divalent phenol compound to the number of equivalents of the epoxy group of the epoxy resin B (the number of equivalents of epoxy group / the number of equivalents of phenolic hydroxyl group) of 100. The epoxy resin molding material according to claim 2 or 3, comprising a reaction product of / 10 to 100/20.
The epoxy resin molding material according to any one of claims 2 to 4, wherein the epoxy resin B contains a compound represented by the following general formula (I).

(In general formula (I), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)
The epoxy resin molding material according to any one of claims 2 to 5, wherein the divalent phenol compound contains hydroquinone.
The epoxy resin molding material according to any one of claims 1 to 6, wherein the curing agent includes a phenol-based curing agent.
The phenolic curing agent includes a compound having a structural unit represented by at least one selected from the group consisting of the following general formula (II-1) and the following general formula (II-2). Epoxy resin molding material.

(In General Formula (II-1) and General Formula (II-2), each R 1 independently represents an alkyl group, an aryl group, or an aralkyl group, and the alkyl group, aryl group, and aralkyl group are substituents. R 2 and R 3 each independently represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and the alkyl group, aryl group, and aralkyl group each have a substituent. M is each independently an integer of 0 to 2. n is each independently an integer of 1 to 7.)
The phenolic curing agent includes a compound having a structural unit represented by at least one selected from the group consisting of the following general formula (III-1) to the following general formula (III-4): Epoxy resin molding material.

(In general formula (III-1) to general formula (III-4), m and n each independently represent a positive integer. Ar independently represents each of the following general formula (III-a) or Represents a group represented by the general formula (III-b).)

(In general formula (III-a) and general formula (III-b), R 11 and R 14 each independently represents a hydrogen atom or a hydroxyl group. R 12 and R 13 each independently represent a hydrogen atom or a carbon number. Represents an alkyl group of 1 to 8.)
The epoxy resin molding material according to any one of claims 1 to 9, further comprising a silane coupling agent.
The epoxy resin molding material according to claim 10, wherein the silane coupling agent includes a silane coupling agent having a phenyl group.
The epoxy resin molding material according to claim 11, wherein the silane coupling agent having a phenyl group has a structure in which a phenyl group is directly bonded to a silicon atom.
The adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler is 5.0 × 10 −6 mol / m 2 to 10.0 × 10 −6 mol / m 2. The epoxy resin molding material according to any one of claims 10 to 12.
The epoxy resin molding material according to any one of claims 1 to 13, wherein the inorganic filler includes at least one selected from the group consisting of magnesium oxide and alumina.
The epoxy resin molding material according to any one of claims 1 to 14, wherein a content of the inorganic filler is 60% by volume to 90% by volume in a solid content.
The epoxy resin molding material according to any one of claims 1 to 15, which is in an A-stage state.
The epoxy resin molding material according to claim 16, wherein a mass reduction rate after heating at 180 ° C for 1 hour is 0.1 mass% or less.
A molded product obtained by molding the epoxy resin molding material according to any one of claims 1 to 17.
The molded product according to claim 18, which has a diffraction peak in a diffraction angle 2θ of 3.0 ° to 3.5 ° in an X-ray diffraction spectrum obtained by an X-ray diffraction method using CuKα rays.
A molded cured product obtained by curing the molded product according to claim 18 or 19.
The molded cured product according to claim 20, wherein the molded product is cured by heating.
The molding hardening according to claim 20 or 21, wherein, in an X-ray diffraction spectrum obtained by an X-ray diffraction method using CuKα rays, a diffraction angle 2θ has a diffraction peak in a range of 3.0 ° to 3.5 °. object.
An epoxy resin molding material containing the epoxy resin A according to any one of claims 1 to 17, wherein the epoxy resin molding material is molded in a temperature range of not less than a phase transition temperature of the epoxy resin A and not more than 150 ° C. Production method.