WO2017145413A1

WO2017145413A1 - Epoxy resin composition, resin sheet, b-stage sheet, c-stage sheet, cured object, metal foil with resin, and metallic substrate

Info

Publication number: WO2017145413A1
Application number: PCT/JP2016/074882
Authority: WO
Inventors: 一也木口; 智雄西山; 片木　秀行; 竹澤　由高; 良洋天野; 田中　賢治; 陶　晴昭; 慎一小杉; 優香吉田
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: TW201800470A

Abstract

An epoxy resin composition which comprises an epoxy resin, a hardener, and a filler, wherein the filler comprises a nitride filler and the epoxy resin comprises one or more polymer compounds each having at least one structural unit selected from the group consisting of structural units represented by general formula (IA) and structural units represented by general formula (IB), the polymer compounds including a dimer compound having, in the molecule, two structural units represented by general formula (II), the dimer compound accounting for 15-28 mass% of the whole epoxy resin.

Description

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

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

In recent years, the amount of heat generated has increased with the miniaturization of electronic and electrical equipment, and so how to dissipate that heat has become an important issue. Examples of the insulating material widely used in these devices include a cured product of a thermosetting resin from the viewpoints of insulation and heat resistance. However, since the thermal conductivity of cured products of thermosetting resins is generally low and is one of the major factors that hinder heat dissipation, development of cured products of thermosetting resins with high thermal conductivity is desired. ing.

As a cured product of a thermosetting resin having high thermal conductivity, a cured product of an epoxy resin composition having a mesogen skeleton in a molecular structure has been proposed (for example, see Patent Document 1). Moreover, an epoxy resin having a specific structure has been proposed as a thermosetting resin having high thermal conductivity and a low softening point (melting point) (see, for example, Patent Document 2).

As an example of a resin composition containing a plurality of resins, an example in which an epoxy compound having a specific mesogen skeleton in the molecular structure and another epoxy resin are mixed is disclosed (for example, see Patent Documents 3 and 4). In Patent Documents 3 and 4, the curing temperature range at the time of producing a cured resin is wider than that of an epoxy compound having a specific mesogen skeleton in the molecular structure, and the production of a cured resin having high thermal conductivity is possible. It has been reported that it will be easier. Furthermore, an insulating composition in which a liquid crystalline polymer and a thermosetting resin exist in a phase-separated state has been proposed (see, for example, Patent Document 5).

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

However, an epoxy resin having a mesogen skeleton in the molecular structure generally has higher crystallinity as the thermal conductivity is higher. A resin composition containing an epoxy resin having a mesogen skeleton in the molecular structure is provided. There are cases where the handling property such as flexibility of the resin composition is inferior in the B-stage state.

The present invention has been made in view of the above-mentioned conventional problems, and is an epoxy resin composition excellent in handling properties in the B-stage state and the thermal conductivity of the cured product, and a resin sheet, B-stage sheet, and C using the same. It is an object to provide a stage sheet, a cured product, a metal foil with resin, and a metal substrate.

Specific means for solving the above problems are as follows: <1> containing an epoxy resin, a curing agent, and a filler;
The filler includes a nitride filler,
The epoxy resin includes a multimeric compound having at least one selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB):
The multimeric compound includes a dimeric compound containing two structural units represented by the following general formula (II) in one molecule,
An epoxy resin composition in which the proportion of the dimer compound in the total epoxy resin is 15% by mass to 28% by mass.

[In General Formula (IA) and General Formula (IB), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents 1 to 8 carbon atoms. Represents an alkyl group. n represents an integer of 0 to 4. ]

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

<2> The dimer compound is represented by a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and the following general formula (II-C). Including at least one selected from the group consisting of compounds,
Total of the compound represented by the following general formula (II-A), the compound represented by the following general formula (II-B) and the compound represented by the following general formula (II-C) in the whole epoxy resin The epoxy resin composition according to <1>, wherein the ratio of is from 15% by mass to 28% by mass.

[In the general formulas (II-A) to (II-C), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents a carbon atom. Represents an alkyl group of formula 1-8. n represents an integer of 0 to 4. ]

<3> The structural unit represented by the general formula (IA) is a structural unit represented by the following general formula (IA ′), and the structural unit represented by the general formula (IB) is represented by the following general formula (IB) The epoxy resin composition according to <1>, which is a structural unit represented by ').

[In general formula (IA ′) and general formula (IB ′), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents a carbon number of 1 Represents an alkyl group of ˜8. n represents an integer of 0 to 4. ]

<4> The dimer compound is a compound represented by the following general formula (II-A ′), a compound represented by the following general formula (II-B ′), and the following general formula (II-C ′). Including at least one selected from the group consisting of the represented compounds,
The compound represented by the following general formula (II-A ′), the compound represented by the following general formula (II-B ′) and the following general formula (II-C ′) in the whole epoxy resin The epoxy resin composition according to <3>, wherein the total proportion of the compounds is 15% by mass to 28% by mass.

[In general formula (II-A ′) to general formula (II-C ′), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently Represents an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 4. ]

<5> The epoxy resin includes an epoxy resin monomer represented by the following general formula (I ″), and a ratio of the epoxy resin monomer in the entire epoxy resin is 57% by mass to 80% by mass. The epoxy resin composition according to any one of <1> to <4>.

[In the 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 curing agent includes a novolak resin including 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). <1>-<5> The epoxy resin composition according to any one of <5>.

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

<7> The curing agent includes a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formula (III-1) to the following general formula (III-4). The epoxy resin composition according to any one of <1> to <5>.

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

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

<8> The epoxy resin composition according to <6> or <7>, wherein the curing agent has a content ratio of a monomer that is a phenol compound constituting the novolak resin of 10% by mass to 50% by mass.

<9> The epoxy resin composition according to any one of <1> to <8>, wherein the content of the filler is 50% by volume to 90% by volume.

<10> The epoxy resin composition according to any one of <1> to <9>, wherein a ratio of the nitride filler in the filler is 10% by volume to 100% by volume.

<11> A resin sheet having a resin composition layer containing the epoxy resin composition according to any one of <1> to <10>.

<12> A B-stage sheet having a semi-cured resin composition layer containing a semi-cured product of the epoxy resin composition according to any one of <1> to <10>.

<13> A C stage sheet having a cured resin composition layer containing a cured product of the epoxy resin composition according to any one of <1> to <10>.

<14> A cured product of the epoxy resin composition according to any one of <1> to <10>.

<15> a metal foil, and a semi-cured resin composition layer including a semi-cured product of the epoxy resin composition according to any one of <1> to <10> disposed on the metal foil. Metal foil with resin.

<16> A metal support, a cured resin composition layer comprising a cured product of the epoxy resin composition according to any one of <1> to <10> disposed on the metal support, and the curing A metal substrate comprising: a metal foil disposed on the resin composition layer.

According to the present invention, an epoxy resin composition excellent in handling property in a B-stage state and thermal conductivity of a cured product, and a resin sheet, a B-stage sheet, a C-stage sheet, a cured product, a metal foil with resin, A metal substrate can be provided.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.
In this specification, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
In the present specification, numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in 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.
In the present specification, the content rate or content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of kinds present in the composition unless otherwise specified. It means the total content or content of substances.
In the present specification, the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
In this specification, the term “layer” refers to the case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. Is also included.

[Epoxy resin composition]
The epoxy resin composition of the present disclosure contains an epoxy resin, a curing agent, and a filler, the filler includes a nitride filler, and the epoxy resin includes a structural unit represented by the following general formula (IA) and A multimer compound having at least one selected from the group consisting of structural units represented by general formula (IB), wherein the multimer compound is represented by the following general formula (II) in one molecule The ratio of the dimer compound, which includes the dimer compound containing two units and occupies the entire epoxy resin, is 15% by mass to 28% by mass.

In general formula (IA) and general formula (IB), R ¹ to R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents one having 1 to 8 carbon atoms. An alkyl group is shown. n represents an integer of 0 to 4.

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

The epoxy resin composition of the present disclosure is excellent in the handling property in the B-stage state and the thermal conductivity of the cured product. Moreover, the resin sheet, B-stage sheet, and resin-attached metal foil using the epoxy resin composition of the present disclosure are excellent in handling properties. Furthermore, the C stage sheet, cured product, and metal substrate using the epoxy resin composition of the present disclosure are excellent in thermal conductivity.
Hereinafter, each component contained in the epoxy resin composition of the present disclosure will be described in detail.

-Epoxy resin-
The epoxy resin used in the present disclosure includes a multimeric compound having at least one selected from the group consisting of a structural unit represented by the general formula (IA) and a structural unit represented by the general formula (IB), The multimeric compound includes a dimeric compound containing two structural units represented by the general formula (II) in one molecule, and the proportion of the dimeric compound in the entire epoxy resin is 15% by mass to 28% by mass. %.
In addition, the “multimeric compound” in the present disclosure refers to a compound containing two or more structural units represented by the general formula (II) in one molecule.

In general formula (IA) and general formula (IB), R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and are a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. Are preferable, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is further preferable.
Further, 2 to ⁴ of R ¹ to R ⁴ are preferably hydrogen atoms, more preferably 3 or 4 are hydrogen atoms, and still more preferably all 4 are hydrogen atoms. . When any of R ¹ to R ⁴ is an alkyl group having 1 to 3 carbon atoms, at least one of R ¹ and R ⁴ is preferably an alkyl group having 1 to 3 carbon atoms.
Specific examples of R ¹ to R ⁴ in the general formula (II) are the same as those in the general formula (IA) and the general formula (IB), and preferred ranges thereof are also the same.

In general formula (IA) and general formula (IB), R ⁵ each independently represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and preferably a methyl group. More preferred.
In the general formulas (IA) and (IB), n represents an integer of 0 to 4, preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and 0. Is more preferable. That is, the benzene ring denoted by R ⁵ in the general formula (IA) and the general formula (IB) preferably has 2 to 4 hydrogen atoms, and may have 3 or 4 hydrogen atoms. More preferably, it has four hydrogen atoms.

The number of structural units represented by the general formula (II) contained in the multimeric compound is arbitrary and is not particularly limited. The average value is preferably 5 or less, more preferably 3 or less. .

In the present disclosure, the structural unit represented by the general formula (IA) is selected from the group consisting of the structural unit represented by the following general formula (IA ′) and the structural unit represented by the following general formula (IA ″) The structural unit represented by the general formula (IB) is composed of a structural unit represented by the following general formula (IB ′) and a structural unit represented by the following general formula (IB ″). Preferably, the structural unit represented by the general formula (IA) is a structural unit represented by the following general formula (IA ′), and is represented by the general formula (IB). The structural unit is more preferably a structural unit represented by the following general formula (IB ′).

In general formula (IA ′), general formula (IB ′), general formula (IA ″), and general formula (IB ″), specific examples of R ¹ to R ⁵ and n include general formula (IA) and general formula It is the same as in formula (IB), and its preferred range is also the same.

The epoxy resin used in the present disclosure includes a dimer compound containing two structural units represented by the general formula (II) in one molecule.
Specific examples of the dimer compound containing two structural units represented by the general formula (II) in one molecule include compounds represented by the following general formula (II-A), the following general formula (II-B) ) And at least one selected from the group consisting of compounds represented by the following general formula (II-C).

In general formula (II-A), general formula (II-B) and general formula (II-C), specific examples of R ¹ to R ⁵ and n are the same as those in general formula (IA) and general formula (IB). The preferred range is also the same.

As a specific example of the dimer compound, when it contains at least one selected from the group consisting of the structural unit represented by the general formula (IA ′) and the structural unit represented by the general formula (IB ′), Selected from the group consisting of a compound represented by the general formula (II-A ′), a compound represented by the following general formula (II-B ′), and a compound represented by the following general formula (II-C ′) There is at least one kind.

Specific examples of R ¹ to R ⁵ and n in the general formula (II-A ′), the general formula (II-B ′) and the following general formula (II-C ′) include the general formula (IA) and the general formula ( It is the same as IB), and its preferable range is also the same.

Specific examples of the dimer compound include at least one selected from the group consisting of a structural unit represented by the general formula (IA ″) and a structural unit represented by the general formula (IB ″). And a compound represented by the following general formula (II-A ″), a compound represented by the following general formula (II-B ″), and a compound represented by the following general formula (II-C ″) At least one selected from the group consisting of:

Specific examples of R ¹ to R ⁵ and n in the general formula (II-A ″), the general formula (II-B ″) and the following general formula (II-C ″) include the general formula (IA) and It is the same as that of general formula (IB), and its preferable range is also the same.

In the present disclosure, specific examples of the dimer compound include a compound represented by the general formula (II-A ′), a compound represented by the general formula (II-B ′), and a general formula (II-C ′). It is preferably at least one selected from the group consisting of compounds represented by

The structure of these dimer compounds is an epoxy resin monomer represented by the following general formula (I ″) used in the epoxy resin synthesis and a divalent phenol having two hydroxyl groups as substituents on one benzene ring. Compare the molecular weight of the structure estimated to be obtained from the reaction of the compound with the molecular weight of the target compound determined by liquid chromatography using a liquid chromatograph equipped with a UV spectrum detector and a mass spectrum detector. Can be determined.
Liquid chromatography is performed using LaChrom II C18 manufactured by Hitachi, Ltd. as the analytical column, tetrahydrofuran as the eluent, and a flow rate of 1.0 ml / min. The UV spectrum detector detects the absorbance at a wavelength of 280 nm. In the mass spectrum detector, the ionization voltage is detected as 2700V.
Details of the epoxy resin synthesis method and evaluation will be described later.

In the present disclosure, the proportion of the dimer compound in the entire epoxy resin is 15% by mass to 28% by mass. This ratio can be calculated | required by the below-mentioned reverse phase chromatography (Reversed Phase Liquid Chromatography, RPLC) measurement.

When the proportion of the dimer compound is less than 15% by mass, the crystallinity of the epoxy resin does not decrease, and the handling properties such as flexibility when the epoxy resin composition is in the B stage state tend to decrease. Moreover, when the ratio of a dimer compound exceeds 28 mass%, the crosslinking density of hardened | cured material will fall, As a result, it exists in the tendency for the thermal conductivity and glass transition temperature (Tg) of hardened | cured material to fall.
The proportion of the dimer compound is preferably 20% by mass to 27% by mass, and more preferably 22% by mass to 25% by mass.

In addition, the epoxy resin may include an epoxy resin monomer 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.
Specific examples of R ¹ to R ⁴ in the general formula (I ″) are the same as those in the general formula (IA) and the general formula (IB), and preferred ranges thereof are also the same.

The proportion of the epoxy resin monomer represented by the general formula (I ″) in the entire epoxy resin is preferably 57% by mass to 80% by mass.
If the ratio of the epoxy resin monomer is 57% by mass or more, this means that there are not too many reactants of the epoxy resin monomer represented by the general formula (I ″) and the divalent phenol compound. For this reason, the crosslink density of the cured product is unlikely to decrease, and as a result, the thermal conductivity and Tg of the cured product tend not to decrease. On the other hand, if the ratio of the epoxy resin monomer is 80% by mass or less, this means that the reaction product of the epoxy resin monomer represented by the general formula (I ″) and the divalent phenol compound is not too small. This means that handling properties such as flexibility when the epoxy resin composition is in a B-stage state are unlikely to decrease, or the crosslinking density of the cured product tends not to decrease.

The proportion of the epoxy resin monomer represented by the general formula (I ″) in the entire epoxy resin is more preferably 59% by mass to 74% by mass, and further preferably 62% by mass to 70% by mass. .

The epoxy resin used in the present disclosure may contain other epoxy resin components in addition to the multimeric compound and the epoxy resin monomer represented by the general formula (I ″). The proportion of the other epoxy resin component in the entire epoxy resin is preferably less than 15% by mass, more preferably 10% by mass or less, further preferably 8% by mass or less, and substantially the other It is particularly preferable that the epoxy resin component is not included.

The RPLC measurement in the present specification uses Mightysil RP-18 manufactured by Kanto Chemical Co., Inc., an analytical RPLC column, and the gradient method is used, and the mixing ratio (volume basis) of the eluent is acetonitrile / tetrahydrofuran / water = 20 / 5/75 to acetonitrile / tetrahydrofuran = 80/20 (20 minutes from the start) and then acetonitrile / tetrahydrofuran = 50/50 (35 minutes from the start). The flow rate is 1.0 ml / min. In this specification, the absorbance at a wavelength of 280 nm is detected, the total area of all detected peaks is defined as 100, the ratio of the area of each corresponding peak is determined, and the value is the content of each compound in the entire epoxy resin. [Mass%].

The epoxy equivalent of the epoxy resin is measured by a perchloric acid titration method.
The epoxy equivalent is preferably 245 g / eq to 300 g / eq, and preferably 250 g / eq to 290 g / eq from the viewpoint of achieving both the handling property when the epoxy resin composition is in the B-stage state and the thermal conductivity of the cured product. More preferably, it is 260 g / eq to 280 g / eq. If the epoxy equivalent of the epoxy resin is 245 g / eq or more, the crystallinity of the epoxy resin does not become too high, and the handling property when the epoxy resin composition is in the B-stage state tends to be difficult to deteriorate. On the other hand, if the epoxy equivalent of the epoxy resin is 300 g / eq or less, the crosslink density of the epoxy resin is unlikely to decrease, and the thermal conductivity of the cured product tends to increase.

In addition, the number average molecular weight (Mn) in the gel permeation chromatography (GPC) measurement of the epoxy resin is 400 from the viewpoint of achieving both handling properties and thermal conductivity of the cured product when the epoxy resin composition is in the B-stage state. Is preferably from 800 to 800, more preferably from 450 to 750, and even more preferably from 500 to 700. If the Mn of the epoxy resin is 400 or more, the crystallinity of the epoxy resin does not become too high, so that the handling property when the epoxy resin composition is in the B stage state tends to be difficult to decrease. If Mn of an epoxy resin is 800 or less, since the crosslinking density of an epoxy resin is hard to fall, it exists in the tendency for the heat conductivity of hardened | cured material to become high.

GPC measurement in this specification uses Tosoh Corporation G2000HXL and 3000HXL as analytical GPC columns, tetrahydrofuran as a mobile phase, a sample concentration of 0.2% by mass, and a flow rate of 1.0 ml / min. Measure. A calibration curve is prepared using a polystyrene standard sample, and Mn is calculated as a polystyrene equivalent value.

An epoxy resin containing a multimeric compound is composed of an epoxy resin monomer represented by the general formula (I ″), a divalent phenol compound having two hydroxyl groups as substituents on one benzene ring, and a curing catalyst described later. It can be synthesized by dissolving in and stirring with heating. The synthesis is also possible by a method in which the epoxy resin monomer is melted and reacted without using a solvent, but it may be necessary to raise the temperature to a temperature at which the epoxy resin monomer melts. For this reason, the synthesis method using a synthetic solvent is preferable from the viewpoint of safety.

As a synthetic solvent, the epoxy resin monomer represented by the general formula (I ″) and a divalent phenol compound having two hydroxyl groups as substituents on one benzene ring are heated to a temperature necessary for the reaction. Any solvent that can be used is not particularly limited.
Specific examples include cyclohexanone, cyclopentanone, ethyl lactate, propylene glycol monomethyl ether, N-methylpyrrolidone and the like.

The amount of the synthetic solvent is such that the epoxy resin monomer represented by the general formula (I ″), the divalent phenol compound having two hydroxyl groups as substituents on one benzene ring, and the curing catalyst can be dissolved at the reaction temperature. That's it. Although the solubility varies depending on the type of raw material before reaction, the type of solvent, etc., if the charged solid content concentration is 20% by mass to 60% by mass, the viscosity of the resin solution after synthesis tends to be in a preferable range.

Examples of the divalent phenol compound having two hydroxyl groups as substituents on 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, resorcinol and hydroquinone are preferably used from the viewpoint of improving the thermal conductivity of the cured product, and hydroquinone is more preferably used. Since hydroquinone has a structure in which two hydroxyl groups are substituted so as to have a para-position, a multimeric compound obtained by reacting with an epoxy resin monomer tends to have a linear structure. For this reason, it is considered that the stacking property of the molecule is high and it is easy to form a higher order structure.
These dihydric phenol compounds may be used individually by 1 type, and may use 2 or more types together.

The type of the curing 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 curing catalyst include imidazole compounds, organic phosphorus 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 of the cured product, an organic phosphine compound; an organic phosphine compound containing 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 A compound having intramolecular polarization formed by adding a compound having a π bond such as a resin; and 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: a complex.

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.

The amount of the curing catalyst is not particularly limited. From the viewpoint of reaction rate and storage stability, with respect to the total mass of the epoxy resin monomer represented by the general formula (I ″) and the divalent phenol compound having two hydroxyl groups as substituents on one benzene ring, The content is preferably 0.1% by mass to 1.5% by mass, and more preferably 0.2% by mass to 1% by mass.

The epoxy resin containing a multimeric compound 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 monomer represented by the general formula (I ″) is charged into a flask or a synthesis kettle, a synthesis solvent is added, and the mixture is heated to a reaction temperature with an oil bath or a heating medium to dissolve the epoxy resin monomer. A dihydric phenol compound having two hydroxyl groups as substituents in one benzene ring is added thereto, and after confirming that the compound is dissolved in the synthesis solvent, a curing catalyst is added to start the reaction. If the reaction solution is taken out after a predetermined time, an epoxy resin solution containing a multimeric compound can be obtained. In addition, if the synthesis solvent is distilled off under reduced pressure under a heating condition in a flask or a synthesis kettle, an epoxy resin containing a multimeric compound is obtained as a solid at room temperature (25 ° C.).

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 curing catalyst, and is preferably in the range of, for example, 100 ° C. to 180 ° C., preferably 100 ° C. to 150 ° C. A range is more preferable. 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, the possibility of gelation tends to be reduced by setting the reaction temperature to 180 ° C. or lower.

In the synthesis of an epoxy resin containing a multimeric compound, the ratio between the epoxy resin monomer represented by the general formula (I ″) and the divalent phenol compound having two hydroxyl groups as substituents on one benzene ring is It can be synthesized by changing. Specifically, the number of equivalents (Ep) of the epoxy group of the epoxy resin monomer represented by the general formula (I ″) and the phenol of a dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring The ratio (Ep / Ph) to the equivalent number (Ph) of the functional hydroxyl group can be synthesized in the range of 100/100 to 100/1. From the viewpoint of handling properties when the epoxy resin composition is in a B-stage state, and heat resistance and thermal conductivity of the cured product, Ep / Ph is preferably in the range of 100/20 to 100/5. More preferably, it is in the range of ˜100 / 10. By setting Ep / Ph to be 100/5 or less, it is possible to suppress a decrease in cross-linking point density and to increase the heat resistance and thermal conductivity of the cured product. On the other hand, by setting Ep / Ph to 100/20 or more, the crystallinity of the resulting multimeric compound is lowered, and handling properties when the epoxy resin composition is in the B-stage state can be improved.

Further, the multimeric compound and the epoxy resin represented by the general formula (I ″) have a mesogenic group in the molecular structure. Patent Document 1 describes that a cured product of an epoxy resin having a mesogenic group in the molecular structure is excellent in thermal conductivity. Further, in WO2013 / 065159, high thermal conductivity and high Tg can be realized by combining a novolak resin in which a divalent phenol compound is novolaked with an epoxy resin monomer represented by the general formula (I ''). It is described.

Here, the mesogenic group refers to a functional group that facilitates the expression of crystallinity or liquid crystallinity by the action of intermolecular interaction. Specific examples thereof include a biphenyl group, a phenylbenzoate group, an azobenzene group, a stilbene group, and derivatives thereof.

Furthermore, the epoxy resin monomer represented by the general formula (I ″) forms a higher-order structure having higher ordering with a filler as a center, and when the thermal conductivity of the cured product is greatly improved, WO2013 / 065159 It is described in the gazette. This is also true for epoxy resins containing multimeric compounds. This is thought to be because a cured product of an epoxy resin having a higher order structure formed by the presence of a filler becomes an efficient heat conduction path, and high heat conductivity is obtained.

Here, the higher order structure means a structure including a higher order structure in which constituent elements are arranged to form a micro ordered structure, and corresponds to, for example, a crystal phase and a liquid crystal phase. The presence or absence of such a higher order structure can be easily determined by observation with a polarizing microscope. In other words, in the observation in the crossed Nicols state, it can be determined by seeing interference fringes due to depolarization.
This higher order structure usually exists in an island shape in the cured product to form a domain structure, and one of the islands corresponds to one higher order structure. The constituent elements of this higher order structure are generally formed by covalent bonds.

In addition, formation of the higher order structure in the hardened | cured material containing a filler can be confirmed as follows.
A cured product (thickness: 0.1 to 20 μm) of a composition obtained by adding 5 volume% to 10 volume% of a filler such as boron nitride filler to a mixture of an epoxy resin, a curing agent, and a curing catalyst is prepared. Observation is performed using a polarizing microscope (for example, BX51 manufactured by Olympus Corporation) in a state where the obtained cured product is sandwiched between slide glasses (thickness: about 1 mm). In the area where the filler is present, an interference pattern is observed around the filler, but in the area where the filler is not present, no interference pattern is observed. This shows that the cured product of the epoxy resin forms a higher order structure with the filler as the center.

Note that the observation is preferably performed in a state in which the analyzer is rotated by 60 ° with respect to the polarizer, not in the crossed Nicols state. When observed in a crossed Nicol state, a region where no interference pattern is observed (that is, a region where the cured product does not form a higher order structure) becomes a dark field and cannot be distinguished from the filler portion. However, by rotating the analyzer by 60 ° with respect to the polarizer, the region where the interference pattern is not observed is not a dark field, and can be distinguished from the filler portion.

However, an epoxy resin monomer having a mesogenic group in the molecular structure is generally easily crystallized, and the melting temperature tends to be higher than that of a general-purpose epoxy resin monomer. The epoxy resin monomer represented by the general formula (I ″) also corresponds to this. However, crystallization can be suppressed by partially polymerizing such an epoxy resin monomer to obtain a multimeric compound. As a result, handling properties when the epoxy resin composition is in the B-stage state are improved.
Specifically, as described above, the epoxy resin monomer represented by the general formula (I ″) and a divalent phenol compound having two hydroxyl groups as substituents on one benzene ring are reacted to produce a multimeric compound. By doing so, the above-mentioned effect can be easily obtained.

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

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

-Curing agent-
The epoxy resin composition of the present disclosure contains a curing agent. The kind of hardening | curing agent is not specifically limited, A conventionally well-known hardening | curing agent can be used. In the present disclosure, a novolak resin obtained by novolacizing a divalent phenol compound (hereinafter sometimes referred to as “specific novolak resin”) is preferable.

Examples of the divalent phenol compound include catechol, resorcinol, hydroquinone, 1,2-naphthalenediol, 1,3-naphthalenediol, and the like. A novolak resin obtained by novolacizing a divalent phenol compound refers to a novolac resin in which these divalent phenol compounds are linked by a methylene chain. By using a divalent phenol compound, the thermal conductivity of the cured product is improved, and by making these compounds novolak, the heat resistance of the cured product is further improved.

The specific novolac resin preferably contains 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).

In general formula (II-1) and general formula (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group, and aralkyl group represented by R ²¹ or R ²⁴ may have a substituent. Examples of the substituent for the alkyl group include an aryl group, a hydroxyl group, and a halogen atom. Examples of the substituent for the aryl group and the aralkyl group include an alkyl group, an aryl group, a hydroxyl group, and a halogen atom.

R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group, and is an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms. An alkyl group having 1 to 6 carbon atoms is more preferable.

m21 and m22 each independently represents an integer of 0-2. If m21 is 2, two R ²¹ may be the same or different and when m22 is 2, two R ²⁴ may be different even in the same. In the present disclosure, m21 and m22 are preferably each independently 0 or 1, and more preferably 0.
N21 and n22 each independently represents an integer of 1 to 7, and represents the content of the structural unit represented by the general formula (II-1) or the structural unit represented by the general formula (II-2). .

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

R ²² , R ²³ , R ²⁵ and R ²⁶ are preferably a hydrogen atom, an alkyl group or an aryl group from the viewpoints of storage stability of the epoxy resin composition and thermal conductivity of the cured product, The alkyl group having 1 to 4 carbon atoms or the aryl group having 6 to 12 carbon atoms is more preferable, and a hydrogen atom is further preferable.
Furthermore, from the viewpoint of heat resistance of the cured product, at least one of R ²² and R ²³ or at least one of R ²⁵ and R ²⁶ is also preferably an aryl group, and is an aryl group having 6 to 12 carbon atoms. Is more preferable.
The aryl group may include a hetero atom in the aromatic group, and is preferably a heteroaryl group in which the total number of hetero atoms and carbon is 6 to 12.

The specific novolac resin may contain one kind of compound having the structural unit represented by the general formula (II-1) or the structural unit represented by the general formula (II-2), or two or more kinds thereof. May be included. The specific novolac resin preferably contains at least a compound having a structural unit represented by the general formula (II-1) from the viewpoint of thermal conductivity of the cured product, and is represented by the general formula (II-1), More preferably, at least a compound having a structural unit derived from is included.

When the compound having the structural unit represented by the general formula (II-1) has a structural unit derived from resorcinol, it may further include at least one kind of partial structure derived from a phenol compound other than resorcinol. Examples of the phenol compound other than resorcinol in the compound having the structural unit represented by the general formula (II-1) include phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-tri Examples thereof include hydroxybenzene and 1,3,5-trihydroxybenzene. The compound having the structural unit represented by the general formula (II-1) may contain one type of partial structure derived from these phenol compounds or a combination of two or more types.
Further, the compound represented by the general formula (II-2) and having a structural unit derived from catechol may contain at least one kind of partial structure derived from a phenol compound other than catechol.

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 aromatic 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 partial structure derived from a phenol compound other than resorcinol includes the heat conductivity of the cured product, the adhesiveness and the storage stability of the epoxy resin composition. From the viewpoint, at least one selected from the group consisting of phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene A partial structure derived from is preferable, and a partial structure derived from at least one selected from catechol and hydroquinone is more preferable.

In addition, when the compound having the structural unit represented by the general formula (II-1) includes a structural unit derived from resorcinol, the content ratio of the partial structure derived from resorcinol is not particularly limited. From the viewpoint of the 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 Tg and 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 of the cured product, it is particularly preferably 90% by mass or more. preferable.

Furthermore, the specific novolak resin preferably contains a compound having a structure represented by at least one selected from the group consisting of the following general formula (III-1) to the following general formula (III-4).

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

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

The specific novolak resin having a structure represented by at least one selected from the group consisting of the general formula (III-1) to the general formula (III-4) is a method for producing a divalent phenol compound, which will be described later. Can be generated as a secondary.

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

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

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

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

In the general formulas (III-1) to (III-4), Ar ³¹ to Ar ³⁴ are each independently a group derived from dihydroxybenzene (ie, a general group from the viewpoint of achieving excellent thermal conductivity of the cured product) In the formula (III-a), R ³¹ is a hydroxyl group, and R ³² and R ³³ are hydrogen atoms), and a group derived from dihydroxynaphthalene (that is, in the general formula (III-b), R ³⁴ is a hydroxyl group. It is preferably at least one kind selected from the group

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. In addition, “group derived from dihydroxynaphthalene” has the same meaning.

From the viewpoint of productivity of the epoxy resin composition and handling properties in the B-stage state, Ar ³¹ to Ar ³⁴ are preferably groups independently derived from dihydroxybenzene, and 1,2-dihydroxy More preferably, it is at least one selected from the group consisting of a group derived from benzene (catechol) and a group derived from 1,3-dihydroxybenzene (resorcinol). From the viewpoint of particularly improving the thermal conductivity of the cured product, Ar ³¹ to Ar ³⁴ preferably include at least a group derived from resorcinol.
From the viewpoint of particularly improving the thermal conductivity of the cured product, the structural unit represented by n31 to n34 preferably contains at least a partial structure derived from resorcinol.

When the specific novolac resin includes a partial structure derived from resorcinol, the content of the partial structure derived from resorcinol is represented by at least one of general formula (III-1) to general formula (III-4) It is preferably 55% by mass or more in the total mass of the compound having a structure, more preferably 60% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. preferable.

M31 to m34 and n31 to n34 in the general formulas (III-1) to (III-4) are each m / n = 1 from the viewpoint of handling properties when the epoxy resin composition is in a B-stage state. / 5 to 20/1 is preferable, 5/1 to 20/1 is more preferable, and 10/1 to 20/1 is still more preferable. In addition, (m + n) is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less from the viewpoint of handling properties when the epoxy resin composition is in the B-stage state. In addition, the lower limit of (m + n) is not particularly limited. Here, when n is n31, m is m31, when n is n32, m is m32, when n is n33, m is m33, and when n is n34, m is m34.

The specific novolac resin having a structure represented by at least one selected from the group consisting of the general formula (III-1) to the general formula (III-4) is particularly a dihydroxybenzene in which Ar ³¹ to Ar ³⁴ are substituted or unsubstituted. , And at least one kind of substituted or unsubstituted dihydroxynaphthalene, it is easy to synthesize and compared to a novolak resin or the like obtained by simply novolacizing these, and a novolak resin having a low softening point tends to be obtained. . Therefore, there is an advantage that the production and handling of an epoxy resin composition containing such a novolak resin as a curing agent is also facilitated.
Whether the novolak resin has a partial structure represented by at least one of general formulas (III-1) to (III-4) is determined by field desorption ionization mass spectrometry (FD-MS). ) To determine whether the fragment component contains a component corresponding to a partial structure represented by at least one of the general formulas (III-1) to (III-4).

The molecular weight of the specific novolac resin is not particularly limited. From the viewpoint of handling properties when the epoxy resin composition is in a B-stage state, the number average molecular weight (Mn) is preferably 2000 or less, more preferably 1500 or less, and further preferably 350 to 1500. preferable. 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 specific novolak resin is not particularly limited. From the viewpoint of the crosslinking density involved in the heat resistance of the cured product, 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. More preferably, it is ˜120 g / eq.

The curing agent may contain a monomer that is a phenol compound constituting the specific novolac resin. There is no restriction | limiting in particular as content ratio (henceforth "monomer content ratio") of the monomer which is a phenol compound which comprises specific novolak resin in a hardening | curing agent. From the viewpoint of thermal conductivity and heat resistance of the cured product and moldability of the epoxy resin composition, the monomer content in the curing agent is preferably 10% by mass to 50% by mass, and 15% by mass to 45% by mass. It is more preferable that the content be 20% by mass to 40% by mass.

When the monomer content is 50% 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 higher-order structure is formed and the cured product is formed. There is a tendency for the thermal conductivity of to improve. Moreover, since it is easy to flow at the time of shaping | molding because it is 10 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 of hardened | cured material.

The content of the curing agent in the epoxy resin composition is not particularly limited. The ratio of the number of equivalents of active hydrogen of the phenolic hydroxyl group in the curing agent (number of equivalents of phenolic hydroxyl group) to the number of equivalents of epoxy group of the epoxy resin (number of equivalents of phenolic hydroxyl group / number of equivalents of epoxy group) is 0.5. Is preferably ˜2, more preferably 0.8˜1.2.

Moreover, the epoxy resin composition may further contain a curing catalyst as necessary. By including a curing catalyst, the epoxy resin composition can be sufficiently cured. The type and content of the curing catalyst are not particularly limited, and an appropriate type and content can be selected from the viewpoint of reaction rate, reaction temperature, storage property, and the like. Specific examples include imidazole compounds, organophosphorus compounds, tertiary amines, quaternary ammonium salts, and the like. These may be used alone or in combination of two or more.
Among these, from the viewpoint of heat resistance of the cured product, at least one selected from the group consisting of an organic phosphine compound and a complex of an organic phosphine compound and an organic boron compound is preferable.

Specific examples of the complex of an organic phosphine compound and an organic boron compound include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, tetrabutylphosphonium tetraphenylborate, and tetraphenylphosphonium butyltriphenyl. Examples thereof include borate, butyltriphenylphosphonium tetraphenylborate, and methyltributylphosphonium tetraphenylborate.

One curing catalyst may be used alone, or two or more curing catalysts may be used in combination. As a method for efficiently producing a B stage sheet, a C stage sheet, and a cured product, which will be described later, there is a method in which two types of curing catalysts having different reaction start temperatures and reaction rates between an epoxy resin and a curing agent are used.

When two or more types of curing catalysts are used in combination, the mixing ratio can be determined without particular limitation depending on the characteristics required for the B stage sheet, the C stage sheet, and the cured product.

When the epoxy resin composition contains a curing catalyst, from the viewpoint of moldability of the epoxy resin composition, the content of the curing catalyst is 0.5% by mass to 1.5% by mass of the total mass of the epoxy resin and the curing agent. It is preferably 0.5% by mass to 1% by mass, more preferably 0.6% by mass to 1% by mass.

-Filler-
The epoxy resin composition of the present disclosure contains a filler. The filler includes at least a nitride filler from the viewpoint of thermal conductivity. Examples of the material for the nitride filler include boron nitride, silicon nitride, and aluminum nitride. The material for the nitride filler is preferably at least one of boron nitride and aluminum nitride from the viewpoint of thermal conductivity. The material of the nitride filler is more preferably boron nitride from the viewpoint of insulation.

Note that whether or not the nitride filler is contained in the epoxy resin composition or a semi-cured product or a cured product thereof can be confirmed by, for example, energy dispersive X-ray analysis (EDX). In particular, by combining a scanning electron microscope (SEM) and EDX, it is also possible to confirm the distribution state of the nitride filler in the cross section of the epoxy resin composition or a semi-cured product or a cured product thereof.

When boron nitride is used as the material of the nitride filler, the crystal form of boron nitride may be any of hexagonal, cubic and rhombohedral, and the particle size is easy Hexagonal crystal is preferable. Two or more types of boron nitride having different crystal forms may be used in combination.

From the viewpoint of thermal conductivity and viscosity of the varnish when the epoxy resin composition is used in the varnish state, the nitride filler is preferably pulverized or agglomerated. Examples of the particle shape of the nitride filler include round shapes, spherical shapes, and flake shapes. The nitride filler may be aggregated particles in which these particles are aggregated. From the viewpoint of enhancing the filling property of the nitride filler, it is preferable that the ratio of the major axis to the minor axis (aspect ratio) is a round shape or a spherical shape of 3 or less, more preferably a round shape having an aspect ratio of 2 or less. Or it is a spherical shape, and a spherical shape is more preferable.
The aspect ratio of the particles means a value obtained by imaging particles using an electron microscope or the like, measuring the major axis and minor axis of each particle, and calculating the arithmetic average of the ratio of the major axis to the minor axis. . In the present disclosure, the major axis of the particle refers to the length of the circumscribed rectangle of the particle, and the minor axis of the particle refers to the width of the circumscribed rectangle of the particle.
Further, the term “spherical particles” means that the aspect ratio is 1.5 or less.

Among these, agglomerated hexagonal boron nitride particles are preferable. Since the agglomerated hexagonal boron nitride particles have many gaps, the particles are easily crushed and deformed by applying pressure to the particles. Therefore, even if the filler content is lowered in consideration of the applicability of the varnish of the epoxy resin composition, the substantial filler content can be increased by compressing the epoxy resin composition with a press after application. It becomes possible. From the viewpoint of easy formation of a heat conduction path by contact between fillers having high thermal conductivity, the particle shape of the filler is more rounded or flake shaped than the spherical shape, and the number of particle contact points increases. Although considered to be preferable, spherical particles are preferable from the viewpoint of filler filling property, thixotropic property of the epoxy resin composition and viscosity.
In the present disclosure, nitride fillers having different particle shapes may be used alone or in combination of two or more.

In view of filler filling properties, other fillers other than the nitride filler may be used in combination in order to fill the gaps in the nitride filler. The other filler material is not particularly limited as long as it is an inorganic compound having an insulating property. In the present disclosure, an inorganic compound having “insulating properties” means that the volume resistivity of the inorganic compound is 10 ¹² Ωcm or more.
Other filler materials preferably have high thermal conductivity. Specific examples of other filler materials include beryllium oxide, aluminum oxide (alumina), magnesium oxide, silicon oxide, talc, mica, aluminum hydroxide, barium sulfate, and the like. Among these, aluminum oxide and magnesium oxide are preferable from the viewpoint of thermal conductivity.

There is no restriction | limiting in particular as volume average particle diameter (D50) of a nitride filler, and it is preferable that it is 100 micrometers or less from a viewpoint of a moldability, and varnish at the time of using heat conductivity and an epoxy resin composition in a varnish state The thickness is more preferably 20 μm to 100 μm from the viewpoint of thixotropic properties, and further preferably 20 μm to 60 μm from the viewpoint of insulation.

The filler may exhibit a particle size distribution having a single peak or may exhibit a particle size distribution having two or more peaks. In the present disclosure, from the viewpoint of the filling rate, a filler showing a particle size distribution having two or more peaks is preferable, and a filler showing a particle size distribution having three or more peaks is more preferable.

When the filler exhibits a particle size distribution having three peaks, the first peak present in the range of 0.1 μm to 0.8 μm, the second peak present in the range of 1 μm to 8 μm, and 20 μm to 60 μm It is preferable to have a third peak existing in the range of. In order for the filler to have a particle size distribution having the first, second and third peaks, the first filler having an average particle size of 0.1 μm to 0.8 μm as small particle size particles, It is preferable to use a second filler having an average particle diameter of 1 μm to 8 μm as the medium particle diameter and a third filler having an average particle diameter of 20 μm to 60 μm as the large particle diameter.
When the filler has a particle size distribution having the first, second and third peaks described above, the filler filling rate tends to be further improved, and the thermal conductivity tends to be further improved. From the viewpoint of filler filling properties, the average particle diameter of the third filler is preferably 30 μm to 50 μm, and the average particle diameter of the second filler is 1/15 to 1/1 / of the average particle diameter of the third filler. The average particle diameter of the first filler is preferably 1/10 to 1/4 of the average particle diameter of the second filler.

The particle size distribution of the filler refers to a volume cumulative particle size distribution measured using a laser diffraction method. Moreover, the average particle diameter of a filler says the particle diameter from which volume cumulative particle size distribution measured using a laser diffraction method will be 50%.
The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring apparatus (for example, LS13 manufactured by Beckman Coulter, Inc.). The filler dispersion for measurement can be obtained by introducing a filler into a 0.1% by mass sodium metaphosphate aqueous solution, ultrasonically dispersing the filler, and adjusting the concentration to an appropriate light amount in terms of device sensitivity.
From the measured volume cumulative particle size distribution, it is determined whether the filler exhibits a particle size distribution having a single peak or a particle size distribution having two or more peaks.

When the filler includes the first filler, the second filler, and the third filler, the nitride filler is preferably used as the third filler. The first filler and the second filler may be nitride fillers or other fillers. The material of the first filler and the second filler may be at least one of aluminum nitride and aluminum oxide from the viewpoint of thermal conductivity and thixotropic modification of the varnish when the epoxy resin composition is used in the varnish state. preferable.

The content of the filler in the epoxy resin composition is preferably 50% by volume to 90% by volume from the viewpoint of moldability, and more preferably 60% by volume to 85% by volume from the viewpoint of thermal conductivity. Preferably, from the viewpoint of thixotropy of the varnish when the epoxy resin composition is used in the varnish state, it is more preferably 65% by volume to 78% by volume. When the content of the filler on the volume basis is within the above range, there is a tendency to form an insulating resin cured product having flexibility before curing and excellent in thermal conductivity after curing.

In some embodiments, the proportion of the nitride filler in the filler is preferably 10% by volume to 100% by volume from the viewpoint of insulating properties, and the thixotropic properties of the varnish when the epoxy resin composition is used in the varnish state. From the viewpoint, it is more preferably 20% by volume to 90% by volume, and further preferably 30% by volume to 85% by volume from the viewpoint of thermal conductivity.
Further, the proportion of the nitride filler in the filler is preferably 50% by volume to 95% by volume in other embodiments, more preferably 60% by volume to 95% by volume from the viewpoint of filling properties. From the viewpoint of thermal conductivity, it is more preferably 65% by volume to 92% by volume.

In addition, the volume-based content rate of the filler in an epoxy resin composition is measured as follows.
First, the mass (Wc) of the epoxy resin composition at 25 ° C. is measured, and the epoxy resin composition is heated in air at 400 ° C. for 2 hours and then at 700 ° C. for 3 hours to decompose and burn the resin component. Then, the mass (Wf) of the remaining filler at 25 ° C. is measured. Next, the density (df) of the filler at 25 ° C. is obtained using an electronic hydrometer or a specific gravity bottle. Next, the density (dc) of the epoxy resin composition at 25 ° C. is measured by the same method. Next, the volume (Vc) of the epoxy resin composition and the volume (Vf) of the remaining filler are obtained, and the volume of the remaining filler is divided by the volume of the epoxy resin composition as shown in (Formula 1). The volume ratio (Vr) is obtained.

(Formula 1)
Vc = Wc / dc
Vf = Wf / df
Vr (%) = (Vf / Vc) × 100

Vc: Volume of the epoxy resin composition (cm ³ )
Wc: mass of epoxy resin composition (g)
dc: Density of epoxy resin composition (g / cm ³ )
Vf: Volume of filler (cm ³ )
Wf: Mass of filler (g)
df: density of the filler (g / cm ³ )
Vr: Volume ratio of filler (%)

Further, the content based on the mass of the filler is not particularly limited. Specifically, when the epoxy resin composition is 100 parts by mass, the filler content is preferably 1 part by mass to 99 parts by mass, and more preferably 50 parts by mass to 97 parts by mass. More preferably, it is 70 to 95 parts by mass. When the filler content is within the above range, higher thermal conductivity can be achieved.

-Other ingredients-
The epoxy resin composition may contain other components in addition to the above components, if necessary. Examples of other components include a solvent, an elastomer, a silane coupling agent, a dispersant, and an anti-settling agent.

The epoxy resin composition may contain at least one kind of solvent. The solvent is not particularly limited as long as it does not inhibit the curing reaction of the epoxy resin composition, and a commonly used organic solvent can be appropriately selected and used. Specific examples of the solvent include methyl ethyl ketone, cyclohexanone, ethyl lactate and the like. When the epoxy resin composition contains a solvent, the content of the solvent contained in the epoxy resin composition is preferably 10% by mass to 40% by mass, and more preferably 10% by mass to 35% by mass. More preferably, the content is 15% by mass to 30% by mass.

The epoxy resin composition preferably contains at least one silane coupling agent. By including the silane coupling agent, the thermal conductivity and the insulation reliability tend to be further improved. This can be considered, for example, because the silane coupling agent plays a role of forming a covalent bond between the filler surface and the resin surrounding the filler (corresponding to a binder agent).

A commercially available silane coupling agent may be used. Silane coupling with functional groups such as epoxy groups, amino groups, mercapto groups, ureido groups, hydroxyl groups, etc., considering compatibility with epoxy resins or curing agents and reduction of heat conduction loss at the interface between resin and filler It is preferable to use an agent.

Specifically, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3 Mention may be made of aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-ureidopropyltriethoxysilane. Also included are silane coupling agent oligomers represented by SC-6000KS2 (manufactured by Hitachi Chemical Techno Service Co., Ltd.).
These silane coupling agents may be used alone or in combination of two or more.

When the epoxy resin composition contains a silane coupling agent, the content of the silane coupling agent in the epoxy resin composition is not particularly limited. For example, the content is preferably 0.01% by mass to 0.1% by mass in the solid content of the epoxy resin composition.

The silane coupling agent only needs to be contained in the epoxy resin composition, and may be present in a state where the surface of the filler is coated or may be present alone in the epoxy resin composition.

The method for adding the silane coupling agent to the epoxy resin composition is not particularly limited. Specifically, the integral method added when mixing other materials such as epoxy resin, curing agent, filler, etc., after mixing a certain amount of silane coupling agent with a small amount of epoxy resin, There are a master batch method of mixing with a material, a pretreatment method of mixing a filler and a silane coupling agent before mixing with another material such as an epoxy resin, and treating the surface of the filler with the silane coupling agent in advance. In addition, the pretreatment method includes a dry method in which an undiluted solution or solution of a silane coupling agent is dispersed together with a filler by high-speed stirring, and the filler is slurried with a dilute solution of the silane coupling agent. There is a wet method or the like in which the filler surface is treated with a silane coupling agent by being immersed.

The adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the filler is preferably 5.0 × 10 ⁻⁶ mol / m ² to 10.0 × 10 ⁻⁶ mol / m ² . More preferably, it is 5 × 10 ⁻⁶ mol / m ² to 9.5 × 10 ⁻⁶ mol / m ² , and 6.0 × 10 ⁻⁶ mol / m ² to 9.0 × 10 ⁻⁶ mol / m. ² is more preferable.

The measuring method of the adhesion amount of the silicon atom derived from the silane coupling agent per specific surface area of the filler is as follows.
First, the BET method is mainly applied as a method for measuring the specific surface area of the 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, the silicon atom derived from the silane coupling agent present on the surface of the filler can be quantitatively measured by ²⁹ Si CP / MAS (Cross Polarization) / (Magic Angle Spinning) solid-state NMR (Nuclear Magnetic Resonance). Since this CP / MAS solid-state NMR (for example, JNM-ECA700 manufactured by JEOL Ltd.) has high resolution, even when the filler contains silica, the silicon atom derived from silica as the filler and the silicon derived from the silane coupling agent It is possible to distinguish atoms.
In the case where silica is not contained in the filler, silicon atoms derived from the silane coupling agent can be quantified also by a fluorescent X-ray analyzer (for example, Supermini 200 manufactured by Rigaku Corporation).

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

-Physical properties of epoxy resin composition-
When the epoxy resin composition contains a solvent, the viscosity of the epoxy resin composition at 25 ° C. is preferably 0.5 Pa · s to 5 Pa · s, and preferably 0.5 Pa · s to 4 Pa · s. More preferably, it is 1 Pa · s to 3 Pa · s. The viscosity at 25 ° C. of the epoxy resin composition was measured at a temperature of 25 ° C. at a shear rate of 5.0 s ⁻¹ using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0 °). Value.
Further, the variation index at 25 ° C. of the epoxy resin composition is preferably 3 to 15, more preferably 3.5 to 10, and further preferably 4 to 7.
The variation index of the epoxy resin composition was (viscosity at a shear rate of 0.5 s ⁻¹ ) / (5.0 s ⁻ ) when the viscosity of the composition kept at 25 ° C. was measured using a rheometer. (Viscosity at a shear rate of ¹ ). Specifically, the “thickening index” is measured as a shear viscosity at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0 °).

[Resin sheet]
The resin sheet of this indication has a resin composition layer containing the epoxy resin composition of this indication. The resin composition layer may be one layer or two or more layers. The resin sheet of the present disclosure may further include a release film on the resin composition layer as necessary.
The resin sheet is, for example, a varnish-like epoxy resin composition (hereinafter also referred to as “resin varnish”) prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition, and a release film such as a PET film. It can manufacture by drying after giving on top.

The resin varnish can be applied by a known method. Specific examples include methods such as comma coating, die coating, lip coating, and gravure coating. As a method for applying a resin varnish for forming a resin composition layer with a predetermined thickness, a comma coating method for passing an object to be coated between gaps, a die coating method for applying a resin varnish with a flow rate adjusted from a nozzle, etc. Apply. For example, when the thickness of the resin composition layer before drying is 50 μm to 500 μm, it is preferable to use a comma coating method.

The drying method is not particularly limited as long as at least a part of the organic solvent contained in the resin varnish can be removed, and can be appropriately selected from commonly used drying methods.

The density of the resin sheet is not particularly limited, and is usually 3.0 g / cm ³ to 3.4 g / cm ³ . Considering compatibility between flexibility and thermal conductivity, the density of the resin sheet is preferably 3.0 g / cm ³ to 3.3 g / cm ³ , and preferably 3.1 g / cm ³ to 3.3 g / cm ³ . More preferably. The density of a resin sheet can be adjusted with the compounding quantity of a filler, for example.
In the present disclosure, the density of the resin sheet refers to the density of the resin composition layer, and when the resin sheet has two or more resin composition layers, it refers to the average value of the densities of all the resin composition layers. Moreover, when the release film is contained in the resin sheet, it means the density of the resin composition layer excluding the release film.

The resin sheet has a first resin composition layer containing an epoxy resin composition and a second resin composition layer containing an epoxy resin composition laminated on the first resin composition layer. Is preferred. For example, the resin sheet is preferably a laminate of a first resin composition layer formed from an epoxy resin composition and a second resin composition layer formed from an epoxy resin composition. Thereby, the withstand voltage can be further improved. The epoxy resin compositions forming the first resin composition layer and the second resin composition layer may have the same composition or different compositions. It is preferable that the epoxy resin composition which forms a 1st resin composition layer and a 2nd resin composition layer is the same composition from a heat conductive viewpoint.

In the case where the resin sheet is a laminate, it is preferable that the first resin composition layer and the second resin composition layer formed from the epoxy resin composition are overlaid. With such a configuration, the withstand voltage tends to be further improved.

This can be considered as follows, for example. That is, by overlapping two resin composition layers, a thinned portion (pinhole or void) that can exist in one resin composition layer is compensated by the other resin composition layer. . Thereby, it can be considered that the minimum insulation thickness can be increased and the withstand voltage is further improved. The probability of occurrence of pinholes or voids in the resin sheet manufacturing method is not high, but by overlapping two resin composition layers, the probability of overlap of thin portions becomes the square, and the number of pinholes or voids is zero. It will approach. Since the dielectric breakdown occurs at a place where the insulation is weakest, it can be considered that the effect of further improving the withstand voltage can be obtained by overlapping the two resin composition layers. Furthermore, it can be considered that by overlapping the two resin composition layers, the contact probability between the fillers is improved, and the effect of improving the thermal conductivity is also produced.

The method for producing a resin sheet includes a step of obtaining a laminate by stacking a second resin composition layer formed from an epoxy resin composition on a first resin composition layer formed from an epoxy resin composition, It is preferable to include a step of subjecting the obtained laminate to a heat and pressure treatment. With such a manufacturing method, the withstand voltage tends to be further improved.

The thickness of the resin sheet can be appropriately selected according to the purpose. For example, the thickness of the resin composition layer 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.

[B stage sheet]
The B stage sheet of the present disclosure has a semi-cured resin composition layer including a semi-cured product of the epoxy resin composition of the present disclosure.
A B stage sheet can be manufactured with a manufacturing method including a process of heat-treating a resin sheet to a B stage state, for example.
By being formed by heat-treating the resin sheet, it is excellent in thermal conductivity and excellent in flexibility and usable time as a B stage sheet.
For the B stage and the C stage described later, the provisions of JIS K6900: 1994 are referred to.
The viscosity of the B-stage sheet is 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 ° C.), whereas the viscosity is 10 ² Pa · s to 10 ³ Pa · s at 100 ° C. Is preferably reduced. Moreover, the cured resin composition layer to be described later does not melt even by heating. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min).

Since the resin composition layer of the resin sheet has hardly any curing reaction, the resin composition layer has flexibility, but is not flexible as a sheet, and the sheet is not self-supporting in a state where a support such as a PET film is removed. , Handling may be difficult. Therefore, the resin composition layer is preferably B-staged by heat treatment described below.
The conditions for heat-treating the resin sheet are not particularly limited as long as the resin composition layer can be semi-cured to the B stage state, and can be appropriately selected according to the configuration of the epoxy resin composition. For the heat treatment, a heat treatment method selected from a hot vacuum press, a hot roll laminate, or the like is preferable for the purpose of eliminating voids in the resin composition layer generated when the epoxy resin composition is applied. Thereby, a flat B stage sheet | seat can be manufactured efficiently.
Specifically, for example, the resin composition layer can be semi-cured into a B-stage state by heat-pressing at a heating temperature of 80 ° C. to 180 ° C. for 1 second to 3 minutes under reduced pressure (eg, 1 kPa). . The press pressure can be set to 5 MPa to 20 MPa.

The thickness of the B stage sheet can be appropriately selected according to the purpose, and can be, for example, 50 μm to 350 μm, and is 60 μm to 300 μm from the viewpoint of thermal conductivity, electrical insulation, and sheet flexibility. It is preferable. Moreover, a B stage sheet | seat can also be produced by heat-pressing in the state which laminated | stacked the resin sheet of 2 or more layers.

[C stage sheet]
The C stage sheet of the present disclosure has a cured resin composition layer including a cured product of the epoxy resin composition of the present disclosure.
The C stage sheet can be manufactured, for example, by a manufacturing method including a step of heat-treating a resin sheet or a B stage sheet to a C stage state.
The conditions for heat-treating the resin sheet or the B-stage sheet are not particularly limited as long as the resin composition layer or the semi-cured resin composition layer can be cured to the C-stage state, and appropriately according to the configuration of the epoxy resin composition. You can choose. From the viewpoint of suppressing the generation of voids in the C stage sheet and improving the voltage resistance of the C stage sheet, a heat treatment method such as a thermal vacuum press is preferable for the heat treatment. Thereby, a flat C stage sheet can be manufactured efficiently.
Specifically, for example, the resin composition layer or the semi-cured resin composition layer is cured in a C-stage state by heat pressing at a heating temperature of 150 ° C. to 220 ° C. for 1 minute to 30 minutes and 1 MPa to 20 MPa. Can do.

The thickness of the C stage sheet can be appropriately selected according to the purpose, and can be, for example, 50 μm to 350 μm, and is 60 μm to 300 μm from the viewpoint of thermal conductivity, electrical insulation, and sheet flexibility. It is preferable. Moreover, a C stage sheet | seat can also be produced by heat-pressing in the state which laminated | stacked the resin sheet or B stage sheet | seat of two or more layers.

The C stage sheet preferably has a diffraction peak in the range of diffraction angle 2θ of 1 ° to 10 ° by X-ray diffraction using CuK _α1 line. The C stage sheet having such a diffraction peak has a highly ordered smectic structure among higher order structures, and tends to be excellent in thermal conductivity.

[Cured product]
The cured product of the present disclosure is a cured product of the epoxy resin composition of the present disclosure. There is no restriction | limiting in particular as a method of hardening | curing an epoxy resin composition, The method used normally can be selected suitably. For example, the hardened | cured material of an epoxy resin composition is obtained by heat-processing an epoxy resin composition.
There is no restriction | limiting in particular as a method of heat-processing an epoxy resin composition, and there is no restriction | limiting in particular also about heating conditions. The temperature range of heat processing can be suitably selected according to the kind of epoxy resin and hardening | curing agent which comprise an epoxy resin composition. Moreover, there is no restriction | limiting in particular as time of heat processing, According to the shape of cured | curing material, thickness, etc., it selects suitably.

The cured product preferably has a diffraction peak in the range of diffraction angle 2θ of 1 ° to 10 ° by X-ray diffraction using CuK _α1 line. The cured product having such a diffraction peak has a highly ordered smectic structure among higher order structures, and tends to be excellent in thermal conductivity.

[Metal foil with resin]
The metal foil with a resin of the present disclosure includes a metal foil and a semi-cured resin composition layer including a semi-cured product of the epoxy resin composition of the present disclosure disposed on the metal foil. By having the semi-cured resin composition layer containing the semi-cured product of the epoxy resin composition of the present disclosure, the metal foil with resin of the present disclosure is excellent in thermal conductivity and electrical insulation.
The semi-cured resin composition layer is obtained by heat-treating the epoxy resin composition so as to be in a B stage state.

Examples of the metal foil include gold foil, copper foil, and aluminum foil, and copper foil is generally used.
The thickness of the metal foil is not particularly limited as long as it is 1 μm to 35 μm. In addition, it exists in the tendency which the flexibility of metal foil with a resin improves more by using metal foil of 20 micrometers or less.
As the metal foil, nickel, nickel-phosphorus alloy, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as an intermediate layer, and a copper layer of 0.5 μm to 15 μm is provided on one side of the intermediate layer. Alternatively, a composite foil having a three-layer structure in which a copper layer of 10 μm to 300 μm is provided on the other surface of the intermediate layer, or a composite foil having a two-layer structure in which an aluminum foil and a copper foil are combined can be used.

The metal foil with resin is formed by, for example, forming a resin composition layer (resin sheet) by applying an epoxy resin composition (preferably a resin varnish) on the metal foil and drying it, and then heat-treating the resin composition layer. It can be manufactured by setting the material layer to the B-stage state. The method for forming the resin composition layer is as described above.

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

[Metal substrate]
The metal substrate of the present disclosure is disposed on the metal support, a cured resin composition layer including a cured product of the epoxy resin composition of the present disclosure disposed on the metal support, and the cured resin composition layer. A metal foil.
By disposing a cured resin composition layer containing a cured product of the epoxy resin composition of the present disclosure between the metal support and the metal foil, adhesion, thermal conductivity, and electrical insulation are improved.

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

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

The metal substrate of this indication can be manufactured as follows, for example.
On the metal support such as aluminum, the epoxy resin composition is applied in the same manner as in the case of a metal foil with a resin and dried to form a resin composition layer, and the metal foil is further arranged on the resin composition layer And a metal substrate can be manufactured by heating and pressurizing this and hardening | curing a resin composition layer. In addition, a metal foil with resin is laminated on a metal support so that the semi-cured resin composition layer faces the metal support, and then this is heated and pressurized to cure the semi-cured resin composition layer. It can also be manufactured.

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

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

・ Resin B to Resin F
A part of the resin A represented by the above structure was reacted with a predetermined amount of hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd., hydroxyl equivalent: 55 g / eq), and prepolymerized compounds were used as Resin B to Resin F. .
The ratio (Ep / Ph) between the number of equivalents of epoxy group (Ep) of resin A and the number of equivalents of phenolic hydroxyl group derived from hydroquinone (Ph) was set as follows.
Resin B: 100/8
Resin C: 100/10
Resin D: 100/13
Resin E: 100/15
Resin F: 100/19

<Synthesis of Resin B to Resin F (Prepolymerization)>
In a 500 mL three-necked flask, 50 g (0.118 mol) of the epoxy resin monomer was weighed, and 80 g of propylene glycol monomethyl ether was added thereto. 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 monomer was dissolved and became a transparent solution, Ep / Ph was 100/8 (resin B), 100/10 (resin C), 100/13 (resin D), 100/15. Hydroquinone was added so as to be (resin E) and 100/19 (resin F), and 0.5 g of triphenylphosphine was further added, and heating was continued at an oil bath temperature of 120 ° C. After heating for 5 hours, propylene glycol monomethyl ether was distilled off under reduced pressure from the reaction solution, and the residue was cooled to room temperature (25 ° C.), whereby resin B to resin in which a part of the epoxy resin monomer was prepolymerized F was obtained.

The molecular weight of the structure estimated to be obtained from the reaction between resin A and hydroquinone is collated with the molecular weight of the target compound determined by liquid chromatography performed using a liquid chromatograph equipped with UV and mass spectrum detectors. Thus, it was confirmed that at least one of the compounds having the following structures (dimer compounds) was contained in Resin B to Resin F.
Specifically, liquid chromatography was performed using LaChrom II C18 manufactured by Hitachi, Ltd. as the analytical column, tetrahydrofuran as the eluent, and a flow rate of 1.0 ml / min. In the UV spectrum detector, absorbance at a wavelength of 280 nm was detected. At this time, a compound having the following structure had a peak at a position of 17.4 minutes, and resin A had a peak at a position of 14.9 minutes. . The mass spectrum detector detected an ionization voltage of 2700 V, and the molecular weight of the compound having the following structure was 959 with one proton added.

The solid content of the resin was measured by the heat loss method. Specifically, 1.0 g to 1.1 g of a sample is weighed in an aluminum cup, and the amount measured after being left for 30 minutes in a dryer set at a temperature of 180 ° C. and the amount measured before heating are as follows. Calculated by the formula.
Solid content (%) = (Measured amount after standing for 30 minutes / Measured amount before heating) × 100

The epoxy equivalents of Resin B to Resin F were measured by the perchloric acid titration method.

The contents of the compound having the above structure and the unreacted resin A contained in the resins B to F were measured by reverse phase chromatography (RPLC). Mightysil RP-18 manufactured by Kanto Chemical Co., Inc. was used as the RPLC column for analysis. Using a gradient method, the mixing ratio (volume basis) of the eluent was changed from acetonitrile / tetrahydrofuran / water = 20/5/75 to acetonitrile / tetrahydrofuran = 80/20 (20 minutes from the start) to acetonitrile / tetrahydrofuran = 50/50. The measurement was carried out while changing continuously (35 minutes from the start). The flow rate was 1.0 ml / min. Absorbance at a wavelength of 280 nm was detected, the total area of all detected peaks was taken as 100, the ratio of the area of each corresponding peak was determined, and the value was calculated as the content [% by mass] of each compound in the entire epoxy resin. did.
Table 1 shows the content ratios of the compound having the above structure (dimer compound) and the unreacted resin A contained in the resin B to the resin F.

(Filler)
AA-18 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 18 μm]
AA-3 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 3 μm]
AA-04 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 0.40 μm]
HP-40 [boron nitride particles, manufactured by Mizushima Alloy Iron Co., Ltd., D50: 40 μm, particle shape (aspect ratio): flake-like aggregate (1.5), crystal form: hexagonal crystal]
FAN-f30 [aluminum nitride particles, manufactured by Furukawa Electronics Co., Ltd., D50: 30 μm, particle shape (aspect ratio): spherical shape (1.1)]
FAN-f50 [Aluminum nitride particles, manufactured by Furukawa Electronics Co., Ltd., D50: 50 μm, particle shape (aspect ratio): spherical shape (1.1)]

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

<Synthesis method of CRN>
To a 3 L separable flask equipped with a stirrer, a condenser and a thermometer, 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 were added, and the mixture was heated at 100 ° C. while heating in an oil bath. The temperature was raised to. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system, and the target catechol resorcinol novolak resin CRN was obtained.
Further, when the structure of the obtained CRN was confirmed by FD-MS (field desorption ionization mass spectrometry), the presence of all the partial structures represented by the above 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 above general formula (III-1) is formed first, and this is further subjected to a dehydration reaction, whereby the above general formulas (III-2) to (III-4) are formed. It is considered that a compound having a partial structure represented by at least one of

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

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

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

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

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

(solvent)
CHN: cyclohexanone

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

<Preparation of varnish-like epoxy resin composition>
An epoxy resin, a curing agent, a curing accelerator, a solvent, a filler and an additive were mixed at a ratio shown in Table 2 to obtain a varnish-like epoxy resin composition.

<Preparation of B stage sheet>
The varnish-like epoxy resin composition was applied on a PET film using an applicator and then dried at 120 ° C. for 10 minutes. Thereafter, vacuum thermocompression bonding was performed by a vacuum press under the conditions shown in Table 3 (B stage formation) to obtain a B stage sheet.

<Production of cured product of epoxy resin composition with copper foil>
After peeling off the PET film of the B-stage sheet obtained above, the two copper foils are sandwiched so that the mat surface of the copper foil faces the semi-cured resin composition layer, and the conditions described in Table 3 (Copper foil pasting) was vacuum thermocompression-bonded with a vacuum press. Then, it heated at 150 degreeC for 2 hours and 210 degreeC for 4 hours under atmospheric pressure conditions, and obtained the hardened | cured material of the epoxy resin composition with copper foil.

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

(Confirmation of smectic structure formation)
The copper foil of the cured product of the epoxy resin composition with copper foil obtained above was removed by etching to obtain a C stage sheet. The obtained C stage sheet was cut into a 10 mm square and used as a sample. Using Cu K _alpha 1 line for samples, subjected to X-ray diffraction measurement using a tube voltage 40 kV, tube current 20 mA, the 2 [Theta] is 0.5 ° ~ 30 ° manufactured by Rigaku Corporation X-ray analyzer in the range of, 2 [Theta] is 1 The presence or absence of a smectic structure was confirmed by the presence or absence of a diffraction peak in the range of 10 ° to 10 °.

(Melting point measurement)
Using the differential scanning calorimeter DSC7 (manufactured by PerkinElmer) for the B-stage sheet obtained above, differential scanning calorimetry is performed at a temperature rising rate of 10 ° C./min in the temperature range from 25 ° C. to 350 ° C. From the results obtained, the temperature at which the energy change (endothermic reaction) accompanying the phase transition occurs was defined as the melting point. The pan used for the sample holder was made of aluminum.

(Flexibility measurement)
The varnish-like epoxy resin composition obtained above was applied on a PET film using an applicator, and then dried at 120 ° C. for 10 minutes. The obtained resin sheet was cut out to 150 mm × 50 mm, and a cylinder having a diameter of 40 mm The flexibility was confirmed depending on whether or not it could be wound around the object. The case where winding was possible was set as “possible”, and the case where winding was impossible was set as “impossible”.

(Dielectric breakdown voltage)
The copper foil of the cured product of the epoxy resin composition with copper foil obtained above is etched while leaving the entire surface on one side and leaving a circular pattern with a diameter of 20 mm on the other side. A cured product of the epoxy resin composition (C stage sheet with electrode) was obtained. About the obtained C stage sheet with an electrode, using a dielectric breakdown test apparatus (insulating material test system manufactured by SOKEN), the C stage sheet with an electrode is sandwiched between cylindrical electrodes having a diameter of 10 mm, and the boosting speed is 500 V / s, AC 60 Hz, cut. The dielectric breakdown voltage was measured in an off-current of 10 mA, 25 ° C. and in Fluorinert.

(Glass-transition temperature)
The copper foil of the cured product of the epoxy resin composition with copper foil obtained above was removed by etching to obtain a C stage sheet. The obtained C stage sheet was cut out to 30 mm × 5 mm, and using a tensile vibration test jig with a dynamic viscoelasticity measuring apparatus (RSA II manufactured by TA Instruments Co., Ltd.), frequency: 10 Hz, heating rate: 5 ° C./min. Under these conditions, dynamic viscoelasticity was measured in the temperature range of 40 ° C. to 300 ° C. to determine the glass transition temperature.

(Sheet thickness)
The average thickness of the C stage sheet was obtained as an arithmetic average value by measuring the thickness of 9 points using a micrometer (Mitutoyo Corporation, Micrometer IP65).

Table 2 shows the composition of each epoxy resin composition, and Table 3 shows the evaluation results.

As shown in Table 3, in Examples 1 to 7, the B stage sheet having flexibility and excellent handling properties is obtained by using an epoxy resin in which the proportion of the dimer compound is 15% by mass to 28% by mass. Obtained. Moreover, the hardened | cured material (C stage sheet) of the epoxy resin composition with copper foil formed the smectic structure, and it turned out that it is compatible with high thermal conductivity and dielectric breakdown voltage.
Further, when the copper foil bonding pressures of Comparative Example 3 and Examples 1 to 5 and Comparative Examples 4 and 6 having the same filler composition are compared, fluidity is improved by using Resin B to Resin F. It was found that the pressure for attaching the copper foil can be reduced.

The disclosures of Japanese Patent Application No. 2016-034886 filed on February 25, 2016 and Japanese Patent Application No. 2016-123978 filed on June 22, 2016 are hereby incorporated by reference in their entirety. Captured in the book.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims

Contains epoxy resin, curing agent and filler,
The filler includes a nitride filler,
The epoxy resin includes a multimeric compound having at least one selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB):
The multimeric compound includes a dimeric compound containing two structural units represented by the following general formula (II) in one molecule,
An epoxy resin composition in which the proportion of the dimer compound in the total epoxy resin is 15% by mass to 28% by mass.

[In General Formula (IA) and General Formula (IB), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 5 each independently represents 1 to 8 carbon atoms. Represents an alkyl group. n represents an integer of 0 to 4. ]

[In general formula (II), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]
The dimer compound comprises a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and a compound represented by the following general formula (II-C). Including at least one selected from the group,
Total of the compound represented by the following general formula (II-A), the compound represented by the following general formula (II-B) and the compound represented by the following general formula (II-C) in the whole epoxy resin The epoxy resin composition according to claim 1, wherein the ratio of is from 15% by mass to 28% by mass.

[In the general formulas (II-A) to (II-C), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 5 each independently represents a carbon atom. Represents an alkyl group of formula 1-8. n represents an integer of 0 to 4. ]
The structural unit represented by the general formula (IA) is a structural unit represented by the following general formula (IA ′), and the structural unit represented by the general formula (IB) is represented by the following general formula (IB ′). The epoxy resin composition according to claim 1, which is a structural unit represented.

[In general formula (IA ′) and general formula (IB ′), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 5 each independently represents a carbon number of 1 Represents an alkyl group of ˜8. n represents an integer of 0 to 4. ]
The dimer compound is represented by the following general formula (II-A ′), the following general formula (II-B ′), and the following general formula (II-C ′). Including at least one selected from the group consisting of compounds,
The compound represented by the following general formula (II-A ′), the compound represented by the following general formula (II-B ′) and the following general formula (II-C ′) in the whole epoxy resin The epoxy resin composition according to claim 3, wherein a total ratio of the compounds is 15% by mass to 28% by mass.

[In general formula (II-A ′) to general formula (II-C ′), R 1 to R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 5 each independently Represents an alkyl group having 1 to 8 carbon atoms. n represents an integer of 0 to 4. ]
2. The epoxy resin includes an epoxy resin monomer represented by the following general formula (I ″), and a ratio of the epoxy resin monomer in the entire epoxy resin is 57% by mass to 80% by mass. The epoxy resin composition according to any one of claims 4 to 4.

[In the 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 curing agent includes a novolak resin including 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). The epoxy resin composition according to any one of claims 1 to 5.

[In General Formula (II-1) and General Formula (II-2), R 21 and R 24 each independently represents an alkyl group, an aryl group, or an aralkyl group, and R 22 , R 23 , R 25 and R 26 Each independently represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represents an integer of 0 to 2, and n21 and n22 each independently represents an integer of 1 to 7. ]
2. The curing agent includes a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formula (III-1) to general formula (III-4): The epoxy resin composition according to any one of claims 5 to 6.

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

[In General Formula (III-a) and General Formula (III-b), R 31 and R 34 each independently represent a hydrogen atom or a hydroxyl group. R 32 and R 33 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ]
The epoxy resin composition according to claim 6 or 7, wherein the curing agent has a content ratio of a monomer that is a phenol compound constituting the novolak resin of 10% by mass to 50% by mass.
The epoxy resin composition according to any one of claims 1 to 8, wherein a content of the filler is 50% by volume to 90% by volume.
10. The epoxy resin composition according to claim 1, wherein a proportion of the nitride filler in the filler is 10% by volume to 100% by volume.
A resin sheet having a resin composition layer containing the epoxy resin composition according to any one of claims 1 to 10.
A B-stage sheet having a semi-cured resin composition layer containing a semi-cured product of the epoxy resin composition according to any one of claims 1 to 10.
A C stage sheet having a cured resin composition layer containing a cured product of the epoxy resin composition according to any one of claims 1 to 10.
A cured product of the epoxy resin composition according to any one of claims 1 to 10.
A metal with resin comprising: a metal foil; and a semi-cured resin composition layer comprising a semi-cured product of the epoxy resin composition according to any one of claims 1 to 10 disposed on the metal foil. Foil.
A cured resin composition layer comprising a metal support, a cured product of the epoxy resin composition according to any one of claims 1 to 10 disposed on the metal support, and the cured resin composition A metal substrate comprising: a metal foil disposed on the layer.