JP7828288B2 - Curable composition, thermally conductive material, thermally conductive sheet, and device with thermally conductive layer - Google Patents

Description

The present invention relates to a curable composition, a thermally conductive material, a thermally conductive sheet, and a device with a thermally conductive layer.

Power semiconductor devices used in various electrical appliances such as personal computers, general home appliances, and automobiles have been rapidly becoming smaller in size in recent years. As the size of these devices has increased, it has become more difficult to control the heat generated by these devices.
To address this issue, thermally conductive materials are used to promote heat dissipation from power semiconductor devices.
For example, Patent Document 1 lists a resin composition that can achieve high thermal conductivity after curing, which contains an epoxy resin containing a multifunctional epoxy resin, a curing agent containing a novolac resin having a predetermined structural unit, and an inorganic filler containing nitride particles (Claim 1).

JP 2016-104862 A

Meanwhile, thermally conductive materials are required to have not only excellent thermal conductivity but also excellent heat resistance so that their performance is not easily deteriorated even when used continuously at high temperatures.
The deterioration of the performance of thermally conductive materials at high temperatures is due to an insufficient Tg (glass transition temperature) of the thermally conductive material. That is, if the Tg of the thermally conductive material is insufficient, the adhesion between the thermally conductive material and the object to which the thermally conductive material is to transfer heat is weakened at high temperatures, and the efficiency with which the thermally conductive material transfers heat from the object is reduced. If the Tg of the thermally conductive material is sufficiently high, the thermally conductive material can continue to exhibit excellent thermal conductivity and have good heat resistance. In this specification, a high Tg of a thermally conductive material is also referred to as having excellent heat resistance.

In view of the above circumstances, an object of the present invention is to provide a curable composition that provides a thermally conductive material having excellent thermal conductivity and heat resistance.
Another object of the present invention is to provide a thermally conductive material, a thermally conductive sheet, and a device with a thermally conductive layer, which are related to the curable composition.

After extensive research to solve the above problem, the inventors discovered that the above problem can be solved by the following configuration.

[1]
phenolic compounds,
one or both of a maleimide compound having one or more maleimide groups and a cyanate compound having one or more cyanate groups;
an inorganic material,
The curable composition, wherein the inorganic material comprises an inorganic nitride.
[2]
The maleimide compound is contained therein,
The curable composition according to [1], wherein the maleimide compound is a compound represented by general formula (1):

In the general formula (1), m represents 0 or 1.
n represents 0 or 1.
R ¹ and R ² each independently represent a hydrogen atom or a substituent.
^L1 represents a divalent linking group.
[3]
In the general formula (1), m represents 1, n represents 1, and the divalent linking group represented by L ¹ has 3 to 15 carbon atoms. [2] The curable composition according to [2].
[4]
The maleimide compound is contained therein,
The curable composition according to any one of [1] to [3], wherein the maleimide compound has two of the maleimide groups.
[5]
The curable composition according to any one of [1] to [4], wherein the inorganic material includes boron nitride.
[6]
The curable composition according to [5], wherein the boron nitride comprises aggregated boron nitride having an average particle size of 20 μm or more.
[7]
Further, a surface modifier is included,
The curable composition according to [5] or [6], wherein the boron nitride, together with the surface modifier adsorbed onto the surface of the boron nitride, constitutes surface-modified boron nitride.
[8]
The curable composition according to any one of [1] to [7], further comprising an epoxy compound.
[9]
The maleimide compound is contained, and
The curable composition according to [8], wherein the epoxy compound includes an epoxy compound having a viscosity at 25°C of less than 1000 mPa·s.
[10]
The maleimide compound is contained, and
The curable composition according to [8] or [9], wherein the ratio of the number of hydroxyl groups contained in the phenol compound to the total number of epoxy groups contained in the epoxy compound is 1.2/1.0 to 2.0/1.0.
[11]
The curable composition according to any one of [8] to [10], which satisfies at least one of the following requirements: the phenol compound contains a phenol compound having a triazine skeleton; and the epoxy compound contains an epoxy compound having a triazine skeleton.
[12]
The curable composition according to any one of [1] to [11], further comprising a curing accelerator.
[13]
The curable composition according to [12], wherein the curing accelerator includes a compound containing a phosphorus atom.
[14]
The curable composition according to [12] or [13], wherein the curing accelerator contains a phosphonium salt.
[15]
[15] The curable composition according to any one of [12] to [14], wherein the molecular weight of the curing accelerator is 430 or more.
[16]
The curable composition according to [12] or [13], wherein the curing accelerator comprises a compound represented by general formula (P3):

In formula (P3), R ^p31 to R ^p34 each independently represent a phenyl group which may have a substituent.
[17]
[17] The curable composition according to any one of [1] to [16], further comprising an ion scavenger.
[18]
A thermally conductive material obtained by curing the curable composition according to any one of [1] to [17].
[19]
A thermally conductive sheet comprising the thermally conductive material according to [18].
[20]
[19] The thermal conductive sheet according to [19], wherein the mass change rate calculated by the following formula is less than 1.0%.
Mass change rate (%) = (W2 - W1) / W1 x 100
W1: Mass of the dry thermal conductive sheet after drying in an environment of 120°C for 2 hours. W2: Mass of the hygroscopic thermal conductive sheet after leaving the dry thermal conductive sheet in an environment of 85°C and 85% RH for 24 hours. [21]
A device with a thermally conductive layer, comprising: a device; and a thermally conductive layer comprising the thermally conductive sheet according to [19] or [20], disposed on the device.

According to the present invention, it is possible to provide a curable composition that gives a thermally conductive material having excellent thermal conductivity and heat resistance.
Furthermore, according to the present invention, it is possible to provide a thermally conductive material, a thermally conductive sheet, and a device with a thermally conductive layer, which are related to the curable composition.

The curable composition, the thermally conductive material, the thermally conductive sheet, and the device with a thermally conductive layer of the present invention will be described in detail below.
The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.

In this specification, the term "(meth)acryloyl group" means "either one or both of an acryloyl group and a methacryloyl group." The term "(meth)acrylamide group" means "either one or both of an acrylamide group and a methacrylamide group." The term "(meth)acrylic" means "either one or both of an acrylic group and a methacrylic group."

In this specification, the acid anhydride group may be a monovalent group or a divalent group. When the acid anhydride group represents a monovalent group, examples include substituents obtained by removing any hydrogen atom from acid anhydrides such as maleic anhydride, phthalic anhydride, pyromellitic anhydride, and trimellitic anhydride. When the acid anhydride group represents a divalent group, a group represented by *-CO-O-CO-* is intended (* represents the bonding position).

In this specification, a substituent or the like that is not specified as substituted or unsubstituted may, if possible, further have a substituent (for example, a substituent group Y described below) in the group to the extent that the intended effect is not impaired. For example, the expression "alkyl group" means a substituted or unsubstituted alkyl group (an alkyl group that may have a substituent) to the extent that the intended effect is not impaired.
In addition, in the present specification, when it is stated that a compound may have a substituent, the type, position, and number of the substituent are not particularly limited. The number of the substituents may be, for example, one or two or more. The substituent may be, for example, a monovalent non-metallic atomic group excluding a hydrogen atom, and is preferably a group selected from the following substituent group Y:
In this specification, examples of halogen atoms include chlorine atoms, fluorine atoms, bromine atoms, and iodine atoms.

Substituent group Y:
Halogen atoms (such as -F, -Br, -Cl, and -I), hydroxyl groups, amino groups, carboxylic acid groups and their conjugate base groups, carboxylic anhydride groups, cyanate ester groups, unsaturated polymerizable groups, epoxy groups, oxetanyl groups, aziridinyl groups, thiol groups, isocyanate groups, thioisocyanate groups, aldehyde groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, N-alkylamino groups, N,N-dialkylamino groups, N-arylamino groups, N,N-diarylamino groups, N-alkyl-N-arylamino groups, acyloxy groups, carbamoyloxy groups, N-aryl an alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an N,N-dialkylcarbamoyloxy group, an N,N-diarylcarbamoyloxy group, an N-alkyl-N-arylcarbamoyloxy group, an alkylsulfoxy group, an arylsulfoxy group, an acylthio group, an acylamino group, an N-alkylacylamino group, an N-arylacylamino group, a ureido group, an N'-alkylureido group, an N',N'-dialkylureido group, an N'-arylureido group, an N',N'-diarylureido group, an N'-alkyl-N'-arylureido group, an N-alkylureido group, an N-arylureido group, N'-Alkyl-N-alkylureido group, N'-Alkyl-N-arylureido group, N',N'-Dialkyl-N-Alkylureido group, N',N'-Dialkyl-N-Arylureido group, N'-Aryl-N-Alkylureido group, N'-Aryl-N-Arylureido group, N',N'-Diaryl-N-Alkylureido group, N',N'-Diaryl-N-Arylureido group, N'-Alkyl-N'-Aryl-N-Alkylureido group, N'-Alkyl-N'-Aryl-N-Arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-Alkyl-N -alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N,N-dialkylcarbamoyl group, N-arylcarbamoyl group, N,N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (-SO _3H ) and their conjugate base groups, alkoxysulfonyl groups, aryloxysulfonyl groups, sulfinamoyl groups, N-alkylsulfinamoyl groups, N,N-dialkylsulfinamoyl groups, N-arylsulfinamoyl groups, N,N-diarylsulfinamoyl groups, N-alkyl-N-arylsulfinamoyl groups, sulfamoyl groups, N-alkylsulfamoyl groups, N,N-dialkylsulfamoyl groups, N-arylsulfamoyl groups, N,N-diarylsulfamoyl groups, N-alkyl-N-arylsulfamoyl groups, N-acylsulfamoyl groups and their conjugate base groups, N-alkylsulfonylsulfamoyl groups (-SO ₂ NHSO ₂ (alkyl)) and their conjugate base groups, N-arylsulfonylsulfamoyl groups (-SO ₂ NHSO ₂ (aryl)) and its conjugate base group, N-alkylsulfonylcarbamoyl group (-CONHSO ₂ (alkyl)) and its conjugate base group, N-arylsulfonylcarbamoyl group (-CONHSO ₂ (aryl)) and its conjugate base group, alkoxysilyl group (-Si(Oalkyl) ₃ ), aryloxysilyl group (-Si(Oaryl) ₃ ), hydroxysilyl group (-Si(OH) ₃ ) and its conjugate base group, phosphono group (-PO ₃ H ₂ ) and its conjugate base group, dialkylphosphono group (-PO ₃ (alkyl) ₂ ), diarylphosphono group (-PO ₃ (aryl) ₂ ), alkylarylphosphono group (-PO ₃ (alkyl)(aryl)), monoalkylphosphono group (-PO ₃ and its conjugate base group, monoarylphosphono group (-PO ₃ H(aryl)) and its conjugate base group, phosphonooxy group (-OPO ₃ H ₂ ) and its conjugate base group, dialkylphosphonooxy group (-OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (-OPO ₃ (aryl) ₂ ), alkylarylphosphonooxy group (-OPO ₃ (alkyl)(aryl)), monoalkylphosphonooxy group (-OPO ₃ H(alkyl)) and its conjugate base group, monoarylphosphonooxy group (-OPO ₃ H(aryl)) and its conjugate base group, cyano group, nitro group, aryl group, alkenyl group, alkynyl group, and alkyl group. Furthermore, each of the above groups may further have a substituent (for example, one or more of the above groups) if possible. For example, aryl groups which may have a substituent are also included as groups which can be selected from the substituent group Y.
When the group selected from the substituent group Y has a carbon atom, the group has, for example, 1 to 20 carbon atoms.
The number of atoms other than hydrogen atoms contained in the group selected from the substituent group Y is, for example, 1 to 30.
Furthermore, these substituents may or may not bond to each other or to the group they substitute to form a ring, if possible. For example, an alkyl group (or an alkyl group portion in a group containing an alkyl group as a partial structure, such as an alkoxy group) may be a cyclic alkyl group (cycloalkyl group) or an alkyl group having one or more cyclic structures as a partial structure.

[Composition]
The curable composition of the present invention (hereinafter also simply referred to as "composition") contains a phenol compound, one or both of a maleimide compound having one or more maleimide groups, and a cyanate compound having one or more cyanate groups, and an inorganic substance.
The inorganic material includes an inorganic nitride.
A maleimide compound having one or more maleimide groups and a cyanate compound having one or more cyanate groups are also collectively referred to as a "specific compound."

The mechanism by which the composition of the present invention, having the above-described structure, solves the problems of the present invention is not entirely clear, but the present inventors speculate as follows.
First, the composition of the present invention contains, as an inorganic substance, an inorganic nitride having excellent thermal conductivity.
The composition further contains a phenolic compound and a specific compound as organic components. The specific compound in the composition reacts with the phenolic compound to form a thermally conductive material (cured product) containing an inorganic nitride. It is presumed that the polymer structure of such a thermally conductive material has a high density, thereby improving the thermal conductivity and heat resistance (Tg) of the thermally conductive material.
Furthermore, as described below, the composition can also contain an epoxy compound, in which case the thermal conductivity and heat resistance (Tg) of the thermal conductive material are superior. This is presumably because the polymer structure formed by the reaction of the phenolic compound with the specific compound and the polymer structure formed by the reaction of the phenolic compound with the epoxy compound form an IPN structure (interpenetrating network structure), and further, the hydroxyl groups generated from the epoxy groups undergo a crosslinking reaction with the specific compound (e.g., a reaction between the hydroxyl groups derived from the epoxy group and the double bond of the maleimide group), resulting in the formation of a denser polymer structure.
Furthermore, the formation of a denser polymer structure within the thermal conductive material makes it difficult for water to penetrate the material, reducing its hygroscopicity. Furthermore, when the thermal conductive material is exposed to high temperatures, the thermal decomposition of its components and the generation of volatile small molecules within the material are also reduced. As a result, even when the thermal conductive material is exposed to high temperatures, the evaporation of volatile components from the thermal conductive material and the resulting loss of adhesiveness are prevented, which is thought to further improve the solder heat resistance of the thermal conductive material.
Furthermore, the thermally conductive material formed from the composition of the present invention also has good insulating properties.
Hereinafter, the excellent effects of the present invention will be referred to as the excellent effects of the present invention when the thermal conductive material formed using the composition of the present invention has at least one of excellent thermal conductivity, heat resistance, insulation, moisture absorption suppression, and solder heat resistance.

The ingredients contained in the composition are described in detail below.

[Phenol compounds]
The compositions of the present invention include a phenolic compound.
The phenol compound is a compound having one or more (preferably two or more, more preferably 2 to 10) hydroxyl groups (phenolic hydroxyl groups) directly bonded to an aromatic ring group.
Among these, the phenol compound preferably has a triazine skeleton.
The phenol compound "having a triazine skeleton" means that the compound has one or more (for example, 1 to 5) triazine ring groups.

The phenol compound is preferably a compound represented by general formula (Z).

In the above general formula (Z), if there are multiple groups represented by the same symbol, unless otherwise specified, the multiple groups represented by the same symbol may be the same or different.

In formula (Z), E ¹ to E ⁶ each independently represent a single bond, —NH—, or —NR—.
R represents a substituent, for example, a linear or branched alkyl group having 1 to 5 carbon atoms.
E ¹ to E ⁶ each independently represent preferably —NH— or —NR—, more preferably —NH—.

In formula (Z), ^B1 represents a single bond or a (k+1)-valent organic group.
^B2 represents a single bond or a l+1-valent organic group.
^B3 represents a single bond or an (m+1)-valent organic group.
^B4 represents a single bond or an (n+1)-valent organic group.
The values of k, l, m, and n in the k+1-valent organic group, the l+1-valent organic group, the m+1-valent organic group, and the n+1-valent organic group are the same as the values of k, l, m, and n specified in general formula (Z).
In addition, when r is 2 or more and the values of m present in a plurality of groups are different, the value of m in the (m+1)-valent organic group represented by ^B3 is the same as the value of m indicating the number of ^X3 to which ^B3 is bonded.

Examples of the organic group represented by B ¹ to B ⁴ include groups in which j hydrogen atoms have been removed from a hydrocarbon having 1 to 20 carbon atoms and which may have a heteroatom, where j refers to k+1, l+1, m+1, or n+1.
Here, examples of the hydrocarbon before removing the j hydrogen atoms include one or more hydrocarbons selected from the group consisting of an aliphatic hydrocarbon having 1 to 20 carbon atoms which may have a substituent, an aliphatic ring having 3 to 20 carbon atoms which may have a substituent, and an aromatic ring having 3 to 20 carbon atoms which may have a substituent. Furthermore, the one or more hydrocarbons may be further combined with one or more divalent linking groups selected from the group consisting of -O-, -S-, -CO-, -NR ^N - (R ^N is a hydrogen atom or a substituent), and -SO ₂ -.
Examples of aliphatic hydrocarbons having 1 to 20 carbon atoms include methane, ethane, propane, butane, pentane, hexane, and heptane.
Examples of the aliphatic ring having 3 to 20 carbon atoms include a cyclohexane ring, a cycloheptane ring, a norbornane ring, and an adamantane ring.
Examples of aromatic rings having 3 to 20 carbon atoms include aromatic hydrocarbons having 6 to 20 carbon atoms and aromatic heterocycles having 3 to 20 carbon atoms.
Examples of aromatic hydrocarbons having 6 to 20 carbon atoms include a benzene ring, a naphthalene ring, and an anthracene ring. Examples of aromatic heterocycles having 3 to 20 carbon atoms include a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, a carbazole ring, an indole ring, and a benzothiazole ring.

In general formula (Z), k, l, m, and n each independently represent an integer of 0 or greater, provided that the sum of k, l, r×m, and n is 2 or greater, and is preferably an integer of 2 to 12, and more preferably an integer of 4 to 8.
The value of m in "r x m" is the average value of multiple possible m's.
k, l, m, and n each independently represent preferably an integer of 0 to 5, more preferably an integer of 1 or 2.
For example, k is preferably 1 or more (e.g., 1 to 2), l is preferably 1 or more (e.g., 1 to 2), m is preferably 1 or more (e.g., 1 to 2), and n is preferably 1 or more (e.g., 1 to 2).
When k is 0, ^B1 does not have ^X1 . When l is 0, ^B2 does not have ^X2 . When m is 0, ^B3 does not have ^X3 . When n is 0, ^B4 does not have ^X4 .
Furthermore, when ^B1 is a single bond, k is 1. When ^B2 is a single bond, l is 1. When ^B3 is a single bond, m is 1. When ^B4 is a single bond, n is 1.

L represents a divalent organic group.
Examples of the divalent organic group include a divalent aromatic ring group which may have a substituent, a divalent aliphatic hydrocarbon group which may have a substituent, a divalent aliphatic ring group which may have a substituent, -N(R ^NA )-, -CO-, and groups formed by combining these. R ^NA represents an organic group. The groups exemplified as the above divalent organic group may further have -O-, -S-, -N(R ^N )-, and groups formed by combining these.
R 1 ^N represents a substituent. Examples of the substituent represented by R ^{1 N} include a linear or branched alkyl group having 1 to 5 carbon atoms.
Furthermore, examples of the substituent that the aromatic ring group, the aliphatic hydrocarbon group, and the aliphatic ring group may have include linear or branched alkyl groups having 1 to 5 carbon atoms.

Examples of the divalent aromatic ring group include a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and a divalent aromatic heterocyclic group having 3 to 20 carbon atoms.
Examples of aromatic rings constituting a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include monocyclic aromatic rings such as a benzene ring; and polycyclic aromatic rings such as a naphthalene ring and an anthracene ring. Examples of aromatic heterocyclic rings constituting a divalent aromatic heterocyclic group having 3 to 20 carbon atoms include monocyclic aromatic rings such as a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, and a thiazole ring; and polycyclic aromatic rings such as a benzothiazole ring, a carbazole ring, and an indole ring.
The divalent aromatic ring group represented by L includes groups obtained by removing two hydrogen atoms from the above-mentioned examples.

Examples of divalent aliphatic hydrocarbon groups include alkylene groups having 1 to 12 carbon atoms, such as methylene, ethylene, propylene, butylene, pentylene, hexylene, methylhexylene, and heptylene groups.

Examples of the aliphatic ring constituting the divalent aliphatic ring group include a cyclohexane ring, a cycloheptane ring, a norbornane ring, and an adamantane ring.
The aliphatic cyclic group represented by L may be any of the above-listed groups in which two hydrogen atoms have been removed.

The divalent aromatic ring group which may have a substituent, the divalent aliphatic hydrocarbon group which may have a substituent, the divalent aliphatic ring group which may have a substituent, or the group combining -O-, -S-, -NR ^N - or -CO- may be not only a divalent linking group consisting of a combination of two or more of these, but also a divalent linking group consisting of a combination of two or more of the same type of groups (for example, aromatic ring groups) via a single bond.

In the present invention, it is preferable that both ends of L are carbon atoms, in order to obtain a thermally conductive material with better thermal conductivity. The terminal carbon atoms may be part of a cyclic structure.
Furthermore, in the present invention, in order to obtain a thermally conductive material with better thermal conductivity, it is preferable that L in the above general formula (P2) be a divalent organic group having at least one selected from the group consisting of a divalent aromatic ring group which may have a substituent, a divalent aliphatic ring group which may have a substituent, and an alkylene group having two or more carbon atoms which may have a branch, and a divalent organic group having a divalent aromatic ring group which may have a substituent is more preferable in order to obtain better thermal conductivity.

In general formula (Z), r is an integer of 0 or more.
r is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10.

In formula (Z), X ¹ to X ⁴ each independently represent an aromatic ring group having a phenolic hydroxyl group.
The "aromatic ring group having a phenolic hydroxyl group" may be an aromatic ring group having one or more (e.g., 1 to 4) hydroxyl groups (phenolic hydroxyl groups) directly bonded to the aromatic ring. The aromatic ring group may or may not have a substituent other than the hydroxyl group. The aromatic ring group may be monocyclic or polycyclic, and may have a heteroatom as a ring member atom. The number of ring member atoms in the aromatic ring group is preferably 5 to 15, more preferably 6 to 10, and even more preferably 6.
The aromatic ring group is preferably a benzene ring group.
The substituent that the aromatic ring group may have other than the hydroxyl group is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and still more preferably a linear or branched alkyl group having 1 to 6 carbon atoms.

In general formula (Z), at least one of the k ^X1s , l ^X2s , r×m ^X3s , and n ^X4s is preferably an aromatic ring group having a phenolic hydroxyl group and a substituent located at the ortho-position of the phenolic hydroxyl group. The substituent may be located at only one or both of the ortho-positions of the phenolic hydroxyl group.
The value of m in "r x m" is the average value of multiple possible m's.
Furthermore, the "substituent located at the ortho position" is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a linear or branched alkyl group having 1 to 6 carbon atoms.
In other words, of the (k+l+r×m+n) "aromatic ring groups having a phenolic hydroxyl group" represented by any one of X ¹ to X ⁴ , at least one (preferably 30% or more, more preferably 50% or more, even more preferably 65% or more; preferably 100% or less, more preferably 90% or less, even more preferably 80% or less) may represent an "aromatic ring group having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group".

In the aromatic ring groups having a phenolic hydroxyl group represented by X ¹ to X ⁴ , the aromatic ring groups other than "aromatic ring groups having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group" may or may not have a substituent other than a hydroxyl group (phenolic hydroxyl group).
Examples of aromatic ring groups other than "aromatic ring groups having a phenolic hydroxyl group and a substituent positioned at the ortho-position of the phenolic hydroxyl group" include hydroxyphenyl groups.
It is also preferred that at least one (e.g., 1 or 2) of the (k+l+r×m+n) "aromatic ring groups having a phenolic hydroxyl group" represented by any one of X ¹ to X ⁴ is an aromatic ring group other than an "aromatic ring group having a phenolic hydroxyl group and a substituent positioned at the ortho-position of the phenolic hydroxyl group".
In the aromatic ring groups having a phenolic hydroxyl group represented by X ¹ to X ⁴ , the presence of aromatic ring groups other than "an aromatic ring group having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group" is thought to disrupt the symmetry of the compound as a whole, lower the melting point of the compound, and improve the handleability of the semi-cured film formed from the composition.

The phenol compound is also preferably a compound represented by general formula (Z1).
The phenol compound preferably contains a compound represented by general formula (Z1), and the phenol compound may be the compound represented by general formula (Z1) itself. The content of the compound represented by general formula (Z1) is preferably 10 to 100 mass%, more preferably 25 to 100 mass%, and even more preferably 50 to 100 mass%, based on the total mass of the phenol compound.

In formula (Z1), r represents an integer of 0 or greater. r is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10.
L represents a divalent organic group. The divalent organic group represented by L in general formula (Z1) is, for example, the same as the divalent organic group represented by L in general formula (Z1).
R 1 and ^Z represent a hydrogen atom or a substituent.
The substituent represented by R ^Z is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a linear or branched alkyl group having 1 to 6 carbon atoms.
At least one of (3+r) R ^Z's (preferably 30% or more, more preferably 50% or more, even more preferably 65% or more; preferably 90% or less, more preferably 80% or less) may represent a substituent.
At least one (for example, 1 or 2) of the (3+r) R 2 ^Z's in general formula (Z1) may represent a hydrogen atom.
In the benzene ring group to which R ^z (preferably R ^z as a substituent) and OH are bonded in general formula (Z1), it is also preferable that the R ^z (preferably R ^z as a substituent) is located at the para position relative to the NH to which the benzene ring group is bonded.

The phenol compound is also preferably a compound represented by general formula (Z2).
The phenol compound preferably contains a compound represented by general formula (Z2), and the phenol compound may be the compound represented by general formula (Z2) itself. The content of the compound represented by general formula (Z2) is preferably 10 to 100 mass%, more preferably 25 to 100 mass%, and even more preferably 50 to 100 mass%, based on the total mass of the phenol compounds.

In formula (Z2), R 1 ^Z represents a hydrogen atom or a substituent.
At least one of the two R 1 ^Z's preferably represents a substituent, and both of them preferably represent a substituent.
The substituent represented by R 1 ^Z is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms.
The alkyl group may be linear or branched, and is preferably unsubstituted.
In general formula (Z2), two ^Rz 's may be the same or different.

Other preferred phenolic compounds include benzene polyols such as bisphenol A, F, S, AD, benzenediol, and benzenetriol, biphenyl aralkyl phenolic resins, phenol novolac resins, cresol novolac resins, aromatic hydrocarbon formaldehyde resin-modified phenolic resins, dicyclopentadiene phenol adduct resins, phenol aralkyl resins, polyhydric phenol novolac resins synthesized from polyhydric hydroxy compounds and formaldehyde, naphthol aralkyl resins, trimethylolmethane resins, tetraphenylolethane resins, naphthol novolac resins, naphtholphenol co-condensed novolac resins, naphthol-cresol co-condensed novolac resins, biphenyl-modified phenolic resins, biphenyl-modified naphthol resins, aminotriazine-modified phenolic resins, and alkoxy group-containing aromatic ring-modified novolac resins.

The molecular weight of the phenol compound is preferably 225 to 2,000, more preferably 225 to 1,000.
When the molecular weight has a molecular weight distribution, the molecular weight is a weight average molecular weight.

The hydroxyl group content of the phenol compound is preferably 2.0 mmol/g or more, more preferably 4.0 mmol/g or more, and the upper limit is preferably 25.0 mmol/g or less, more preferably 10.0 mmol/g or less.
The hydroxyl group content refers to the number of hydroxyl groups (preferably phenolic hydroxyl groups) contained in 1 g of the phenol compound.
In addition to hydroxyl groups, the phenolic compound may or may not have active hydrogen-containing groups (such as carboxylic acid groups) capable of polymerizing with the epoxy compound. The lower limit of the active hydrogen content of the phenolic compound (the total content of hydrogen atoms in hydroxyl groups, carboxylic acid groups, etc.) is preferably 2.0 mmol/g or more, more preferably 4.0 mmol/g or more. The upper limit is preferably 25.0 mmol/g or less, more preferably 10.0 mmol/g or less.

The composition of the present invention may contain, in addition to the phenol compound, a compound having a group capable of reacting with an epoxy compound (also referred to as "other active hydrogen-containing compounds").
However, in the composition of the present invention, the mass ratio of the content of the other active hydrogen-containing compound to the content of the phenol compound is preferably 0 to 1, more preferably 0 to 0.1, and even more preferably 0 to 0.05.

The content of the phenol compound in the composition is preferably from 3 to 90 mass %, more preferably from 5 to 50 mass %, and even more preferably from 7 to 40 mass %, based on the total solid content of the composition.
The term "solids" refers to components that form the thermally conductive material and does not include solvents. The components that form the thermally conductive material may be components that undergo a reaction (polymerization) to change their chemical structure when forming the thermally conductive material. Furthermore, components that form the thermally conductive material are considered to be solids even if they are liquid.

[Epoxy Compound]
The composition of the present invention also preferably contains an epoxy compound.
An epoxy compound is a compound having at least one epoxy group (oxiranyl group) in one molecule.
The epoxy group is a group obtained by removing one or more hydrogen atoms (preferably one hydrogen atom) from an oxirane ring. If possible, the epoxy group may further have a substituent (such as a linear or branched alkyl group having 1 to 5 carbon atoms).

The number of epoxy groups contained in an epoxy compound is preferably 2 or more, more preferably 2 to 1,000, and even more preferably 2 to 40, per molecule.

The molecular weight of the epoxy compound is preferably at least 150, more preferably at least 300. There is no upper limit to the molecular weight, and for example, it is preferably at most 100,000, more preferably at most 10,000.
When the molecular weight has a molecular weight distribution, the molecular weight is a weight average molecular weight.
In this specification, the number average molecular weight and weight average molecular weight are weight average molecular weights determined by gel permeation chromatography (GPC) in terms of polystyrene.

The epoxy group content of the epoxy compound is preferably from 2.0 to 20.0 mmol/g, more preferably from 5.0 to 15.0 mmol/g.
The epoxy group content refers to the number of epoxy groups contained in 1 g of the epoxy compound.
The epoxy compound also preferably has an aromatic ring group (preferably an aromatic hydrocarbon ring group).
The content of the epoxy compound having an aromatic ring group is preferably 5 to 100 mass %, more preferably 50 to 100 mass %, and even more preferably 70 to 100 mass %, based on the total amount of epoxy compounds.

The epoxy compound may or may not exhibit liquid crystallinity.
That is, the epoxy compound may be a liquid crystal compound, or in other words, a liquid crystal compound having an epoxy group.
Examples of the epoxy compound (which may be a liquid crystalline epoxy compound) include a compound having at least a partial rod-like structure (rod-like compound) and a compound having at least a partial discotic structure (discotic compound).
The rod-shaped compounds and discotic compounds will be described in detail below.

(rod-shaped compound)
Examples of epoxy compounds that are rod-shaped compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. In addition to the low molecular weight compounds described above, high molecular weight compounds can also be used. The high molecular weight compounds are polymerized low molecular weight rod-shaped compounds having reactive groups.
A preferred rod-shaped compound is a rod-shaped compound represented by the following general formula (XXI).
General formula (XXI): Q ¹ -L ¹¹¹ -A ¹¹¹ -L ¹¹³ -ML ¹¹⁴ -A ¹¹² -L ¹¹² -Q ²

In general formula (XXI), ^Q1 and ^Q2 each independently represent an epoxy group, ^L111 , ^L112 , ^L113 , and ^L114 each independently represent a single bond or a divalent linking group, ^A111 and ^A112 each independently represent a divalent linking group (spacer group) having 1 to 20 carbon atoms, and M represents a mesogenic group.
The epoxy groups of ^Q1 and ^Q2 may or may not have a substituent.

In formula (XXI), L ¹¹¹ , L ¹¹² , L ¹¹³ and L ¹¹⁴ each independently represent a single bond or a divalent linking group.
The divalent linking groups represented by L ¹¹¹ , L ¹¹² , L ¹¹³ and L ¹¹⁴ are preferably each independently a divalent linking group selected from the group consisting of -O-, -S-, -CO-, -NR ¹¹² -, -CO-O-, -O-CO-O-, -CO-NR ¹¹² -, -NR ¹¹² -CO-, -O-CO-, -CH ₂ -O-, -O-CH ₂ -, -O-CO-NR ¹¹² -, -NR ¹¹² -CO-O- and -NR ¹¹² -CO-NR ¹¹² -. R ¹¹² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom.
Of these, it is preferable that L ¹¹³ and L ¹¹⁴ each independently represent —O—.
It is preferable that L ¹¹¹ and L ¹¹² each independently represent a single bond.

In formula (XXI), A ¹¹¹ and A ¹¹² each independently represent a divalent linking group having 1 to 20 carbon atoms.
The divalent linking group may contain heteroatoms such as non-adjacent oxygen atoms and sulfur atoms. Among these, alkylene groups, alkenylene groups, and alkynylene groups having 1 to 12 carbon atoms are preferred. The alkylene groups, alkenylene groups, and alkynylene groups may or may not have an ester group.
The divalent linking group is preferably linear and may or may not have a substituent, such as a halogen atom (fluorine atom, chlorine atom, or bromine atom), a cyano group, a methyl group, or an ethyl group.
Among these, A ¹¹¹ and A ¹¹² are each independently preferably an alkylene group having 1 to 12 carbon atoms, more preferably a methylene group.

In formula (XXI), M represents a mesogenic group, and examples of the mesogenic group include known mesogenic groups. Among these, a group represented by formula (XXII) below is preferred.
General formula (XXII): -(W ¹ -L ¹¹⁵ ) _n -W ² -

In general formula (XXII), ^W1 and ^W2 each independently represent a divalent cyclic alkylene group, a divalent cyclic alkenylene group, an arylene group, or a divalent heterocyclic group. ^L115 represents a single bond or a divalent linking group. n represents an integer of 1 to 4.

Examples of ^W1 and ^W2 include 1,4-cyclohexenediyl, 1,4-cyclohexanediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl, 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, and pyridazine-3,6-diyl. In the case of 1,4-cyclohexanediyl, either the trans or cis structural isomer may be used, or a mixture in any ratio may be used. Of these, the trans isomer is preferred.
W ¹ and W ² may each have a substituent. Examples of the substituent include the groups exemplified in the above-mentioned substituent group Y, more specifically, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), a cyano group, an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, and a propyl group), an alkoxy group having 1 to 10 carbon atoms (e.g., a methoxy group and an ethoxy group), an acyl group having 1 to 10 carbon atoms (e.g., a formyl group and an acetyl group), an alkoxycarbonyl group having 1 to 10 carbon atoms (e.g., a methoxycarbonyl group and an ethoxycarbonyl group), an acyloxy group having 1 to 10 carbon atoms (e.g., an acetyloxy group and a propionyloxy group), a nitro group, a trifluoromethyl group, and a difluoromethyl group.
When a plurality of W ^1's are present, the plurality of W ¹ 's may be the same or different.

In general formula (XXII), L ¹¹⁵ represents a single bond or a divalent linking group. Examples of the divalent linking group represented by L ¹¹⁵ include the specific examples of the divalent linking groups represented by L ¹¹¹ to L ¹¹⁴ described above, such as —CO—O—, —O—CO—, —CH ₂ —O—, and —O—CH ₂ —.
When a plurality of L ¹¹⁵ are present, the plurality of L ¹¹⁵ may be the same or different.

Preferred examples of the basic skeleton of the mesogenic group represented by general formula (XXII) are shown below. The mesogenic group may have a substituent substituted on the skeleton.

Among the above skeletons, the biphenyl skeleton is preferred in that the resulting thermally conductive material has better thermal conductivity.
The compound represented by the general formula (XXI) can be synthesized by referring to the method described in JP-A-11-513019 (WO97/00600).
The rod-like compound may be a monomer having a mesogen group as described in JP-A-11-323162 and Japanese Patent No. 4,118,691.

Also preferred are compounds represented by general formula (XXI) in which one or both of "Q ¹ -L ¹¹¹ -" and "-L ¹¹² -Q ² " are replaced with a diglycidylamino group.

Of these, it is preferable that the rod-shaped compound is a compound represented by general formula (E1).

In formula (E1), L ^E1 each independently represents a single bond or a divalent linking group.
Among these, L ^E1 is preferably a divalent linking group.
The divalent linking group is preferably -O-, -S-, -CO-, -NH-, -CH=CH-, -C≡C-, -CH=N-, -N=CH-, -N=N-, an optionally substituted alkylene group, or a group consisting of a combination of two or more of these, and more preferably -O-alkylene group- or -alkylene group-O-.
The alkylene group may be straight-chain, branched-chain, or cyclic, but is preferably a straight-chain alkylene group having 1 to 2 carbon atoms.
A plurality of L ^E1's may be the same or different.

In general formula (E1), L ^E2 each independently represent a single bond, -CH=CH-, -CO-O-, -O-CO-, -C(-CH ₃ )=CH-, -CH=C(-CH ₃ )-, -CH=N-, -N=CH-, -N=N-, -C≡C-, -N=N ⁺ (-O ^- )-, -N ⁺ (-O ^- )=N-, -CH=N ⁺ (-O ^- )-, -N ⁺ (-O ^- )=CH-, -CH=CH-CO-, -CO-CH=CH-, -CH=C(-CN)- or -C(-CN)=CH-.
Among these, it is preferable that each L ^E2 independently represents a single bond, —CO—O—, or —O—CO—.
When a plurality of L ^E2s are present, the plurality of L ^E2s may be the same or different.

In general formula (E1), L ^{and E3} each independently represent a single bond, or an optionally substituted 5- or 6-membered aromatic ring group, an optionally substituted 5- or 6-membered non-aromatic ring group, or a polycyclic group consisting of these rings.
Examples of aromatic and non-aromatic ring groups represented by L ^E3 include optionally substituted 1,4-cyclohexanediyl, 1,4-cyclohexenediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl, 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, and pyridazine-3,6-diyl groups. In the case of the 1,4-cyclohexanediyl group, it may be either a trans or cis structural isomer, or a mixture in any proportion. Of these, the trans isomer is preferred.
Among these, L ^E3 is preferably a single bond, a 1,4-phenylene group, or a 1,4-cyclohexenediyl group.
The substituents possessed by the group represented by L ^E3 are each independently preferably an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, or an acetyl group, and more preferably an alkyl group (preferably having 1 carbon atom).
When a plurality of substituents are present, the substituents may be the same or different.
When a plurality of L ^E3s are present, the plurality of L ^E3s may be the same or different.

In formula (E1), pe represents an integer of 0 or more.
When pe is an integer of 2 or more, a plurality of (-L ^E3 -L ^E2 -) may be the same or different.
Among these, pe is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

In formula (E1), L ^{and E4} each independently represent a substituent.
The substituents are each independently preferably an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, or an acetyl group, and more preferably an alkyl group (preferably having one carbon atom).
A plurality of L ^E4 's may be the same or different from each other. When Ie, which will be described next, is an integer of 2 or more, a plurality of L ^E4's present in _the same (L ^E4 ) Ie may be the same or different from each other.

In formula (E1), each le independently represents an integer of 0 to 4.
In particular, it is preferable that each le independently represents 0 to 2.
A plurality of le's may be the same or different.

Also preferred are compounds represented by general formula (E1) in which one or both of the two "epoxy groups -L ^E1 -" are replaced with a diglycidylaminoalkylene group (preferably a diglycidylaminomethylene group).

The rod-like compound preferably has a biphenyl skeleton, since the resulting thermally conductive material has better thermal conductivity.
In other words, the epoxy compound preferably has a biphenyl skeleton, and in this case, the epoxy compound is preferably a rod-like compound.

(Disco-like compounds)
The discotic epoxy compound has at least a partial discotic structure.
The discotic structure has at least an alicyclic or aromatic ring. In particular, when the discotic structure has an aromatic ring, the discotic compound can form a columnar structure by forming a stacking structure due to intermolecular π-π interactions.
Specific examples of the discotic structure include the triphenylene structure described in Angew. Chem. Int. Ed. 2012, 51, 7990-7993 or JP-A-7-306317, and the tri-substituted benzene structures described in JP-A-2007-002220 and JP-A-2010-244038.

When a disc-shaped compound is used as the epoxy compound, a thermally conductive material with high thermal conductivity can be obtained. The reason for this is thought to be that while rod-shaped compounds can only conduct heat linearly (one-dimensionally), disc-shaped compounds can conduct heat planarly (two-dimensionally) in the normal direction, which increases the number of heat conduction paths and improves thermal conductivity.

The discotic compound preferably has three or more epoxy groups. A cured product of a composition containing a discotic compound having three or more epoxy groups tends to have a high glass transition temperature and high heat resistance.
The number of epoxy groups contained in the discotic compound is preferably 8 or less, more preferably 6 or less.

Specific examples of discotic compounds include those described in C. Destrade et al., Mol. Crysr. Liq. Cryst., vol. 71, page 111 (1981); Quarterly Review of Chemistry, No. 22, Chemistry of Liquid Crystals, edited by the Chemical Society of Japan, Chapter 5, Chapter 10, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., page 1794 (1985); and J. Zhang et al., J. Am. Chem. Soc., vol. 116, page 2655 (1994) and Japanese Patent No. 4592225, in which at least one (preferably three or more) terminal groups are epoxy groups.
Examples of the discotic compound include the triphenylene structure described in Angew. Chem. Int. Ed. 2012, 51, 7990-7993 and JP-A-7-306317, and compounds having a trisubstituted benzene structure in which at least one (preferably three or more) of the terminals is an epoxy group described in JP-A-2007-002220 and JP-A-2010-244038.

As the discotic compound, compounds represented by any one of the following formulae (D1) to (D16) are preferred, from the viewpoint of providing a thermally conductive material with better thermal conductivity.
First, equations (D1) to (D15) will be explained, and then equation (D16) will be explained.
In the following formulas, "-LQ" represents "-LQ" and "QL-" represents "QL-".

In formulas (D1) to (D15), L represents a divalent linking group.
From the viewpoint of achieving better thermal conductivity of the thermal conductive material, L is preferably each independently a group selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, -S-, and combinations thereof, and more preferably a group combining two or more groups selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, and -S-.
The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 10 or less carbon atoms.
The alkylene group, alkenylene group, and arylene group may have a substituent (preferably an alkyl group, a halogen atom, cyano, an alkoxy group, an acyloxy group, or the like).

Examples of L are shown below. In the following examples, the left bond is bonded to the central structure (hereinafter also simply referred to as "central ring") of the compound represented by any one of formulas (D1) to (D15), and the right bond is bonded to Q.
AL represents an alkylene group or an alkenylene group, and AR represents an arylene group.
The alkylene group represented by AL may be linear or branched and has, for example, 1 to 12 carbon atoms. The alkenylene group represented by AL may be linear or branched and has, for example, 2 to 12 carbon atoms. The arylene group represented by AR may be monocyclic or polycyclic and preferably has 6 to 12 ring atoms.

L101:-AL-CO-O-AL-
L102:-AL-CO-O-AL-O-
L103:-AL-CO-O-AL-O-AL-
L104:-AL-CO-O-AL-O-CO-
L105:-CO-AR-O-AL-
L106:-CO-AR-O-AL-O-
L107:-CO-AR-O-AL-O-CO-
L108:-CO-NH-AL-
L109:-NH-AL-O-
L110:-NH-AL-O-CO-
L111:-O-AL-
L112:-O-AL-O-
L113:-O-AL-O-CO-

L114:-O-AL-O-CO-NH-AL-
L115:-O-AL-S-AL-
L116:-O-CO-AL-AR-O-AL-O-CO-
L117:-O-CO-AR-O-AL-CO-
L118:-O-CO-AR-O-AL-O-CO-
L119: -O-CO-AR-O-AL-O-AL-O-CO-
L120: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L121:-S-AL-
L122:-S-AL-O-
L123:-S-AL-O-CO-
L124:-S-AL-S-AL-
L125:-S-AR-AL-
L126:-O-CO-AL-
L127:-O-CO-AL-O-
L128:-O-CO-AR-O-AL-
L129:-O-CO-
L130: -O-CO-AR-O-AL-O-CO-AL-S-AR-
L131:-O-CO-AL-S-AR-
L132: -O-CO-AR-O-AL-O-CO-AL-S-AL-
L133:-O-CO-AL-S-AR-
L134:-O-AL-S-AR-
L135:-AL-CO-O-AL-O-CO-AL-S-AR-
L136:-AL-CO-O-AL-O-CO-AL-S-AL-
L137:-O-AL-O-AR-
L138:-O-AL-O-CO-AR-
L139:-O-AL-NH-AR-
L140:-O-CO-AL-O-AR-
L141: -O-CO-AR-O-AL-O-AR-
L142:-AL-CO-O-AR-
L143:-AL-CO-O-AL-O-AR-

In formulae (D1) to (D15), each Q independently represents a hydrogen atom or a substituent.
Examples of the substituent include the groups exemplified in the above-mentioned substituent group Y. More specifically, examples of the substituent include the above-mentioned reactive functional groups, halogen atoms, isocyanate groups, cyano groups, unsaturated polymerizable groups, epoxy groups, oxetanyl groups, aziridinyl groups, thioisocyanate groups, aldehyde groups, and sulfo groups.
However, when Q is a group other than an epoxy group, Q is preferably stable to the epoxy group.
In formulas (D1) to (D15), one or more (preferably two or more) Q's represent an epoxy group. In particular, from the viewpoint of achieving superior thermal conductivity of the thermal conductive material, it is preferable that all Q's represent an epoxy group.
From the viewpoint of the stability of the epoxy group, it is preferable that the compounds represented by formulas (D1) to (D15) do not have —NH—.

Among the compounds represented by formulas (D1) to (D15), the compound represented by formula (D4) is preferred from the viewpoint of achieving superior thermal conductivity of the thermal conductive material. In other words, the central ring of the discotic compound is preferably a triphenylene ring.
As the compound represented by formula (D4), a compound represented by formula (XI) is preferred from the viewpoint of providing a thermally conductive material with better thermal conductivity.

In formula (XI), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represent *-X ¹¹ -L ¹¹ -P ¹¹ or *-X ¹² -L ¹² -Y ¹² .
The symbol * indicates the bonding position to the triphenylene ring.
Of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ , it is preferred that two or more are *-X ¹¹ -L ¹¹ -P ¹¹ , and three or more are *-X ¹¹ -L ¹¹ -P ¹¹ .
In particular, from the viewpoint of achieving better thermal conductivity of the thermal conductive material, it is preferable that at least one of R ¹¹ and R ¹² , at least one of R ¹³ and R ¹⁴ , and at least one of R ¹⁵ and R ¹⁶ are *-X ¹¹ -L ¹¹ -P ¹¹ .
It is more preferable that R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are all *-X ¹¹ -L ¹¹ -P ^11. In addition, it is even more preferable that R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are all the same.

^X11 each independently represents a single bond, -O-, -CO-, -NH-, -O-CO-, -O-CO-O-, -O-CO-NH-, -O-CO-S-, -CO-O-, -CO-NH-, -CO-S-, -NH-CO-, -NH-CO-O-, -NH-CO-NH-, -NH-CO-S-, -S-, -S-CO-, -S-CO-O-, -S-CO-NH-, or -S-CO-S-.
Among these, ^X11 are each independently preferably -O-, -O-CO-, -O-CO-O-, -O-CO-NH-, -CO-O-, -CO-NH-, -NH-CO- or -NH-CO-O-, more preferably -O-, -O-CO-, -CO-O-, -O-CO-NH- or -CO-NH-, and still more preferably -O-CO- or -CO-O-.

Each L ¹¹ independently represents a single bond or a divalent linking group.
Examples of the divalent linking group include -O-, -O-CO-, -CO-O-, -S-, -NH-, an alkylene group (preferably having 1 to 10 carbon atoms, more preferably having 1 to 8 carbon atoms, and still more preferably having 1 to 7 carbon atoms), an arylene group (preferably having 6 to 20 carbon atoms, more preferably having 6 to 14 carbon atoms, and still more preferably having 6 to 10 carbon atoms), and a group formed from a combination thereof.
Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, and a heptylene group.
Examples of the arylene group include a 1,4-phenylene group, a 1,3-phenylene group, a 1,4-naphthylene group, a 1,5-naphthylene group, and an anthracenylene group, with a 1,4-phenylene group being preferred.

The alkylene group and the arylene group may each have a substituent. The number of substituents is preferably 1 to 3, and more preferably 1. The substitution position of the substituent is not particularly limited. The substituent is preferably a halogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.
The alkylene group and the arylene group are preferably unsubstituted, and the alkylene group is particularly preferably unsubstituted.

Examples of -X ¹¹ -L ¹¹ - include L101 to L143, which are the examples of L mentioned above.

^P11 represents an epoxy group, which may or may not have a substituent.

X ¹² is the same as X ¹¹ , and the preferred conditions are also the same.
L ¹² is similar to L ¹¹ , and the preferred conditions are also similar.
Examples of -X ¹² -L ¹² - include L101 to L143, which are the examples of L described above.

Y ¹² represents a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, or a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms in which one or more methylene groups have been substituted with —O—, —S—, —NH—, —N(CH ₃ )—, —CO—, —O—CO—, or —CO—O—.
When Y ¹² is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, or a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms in which one or more methylene groups have been substituted with —O—, —S—, —NH—, —N(CH ₃ )—, —CO—, —O—CO—, or —CO—O—, one or more hydrogen atoms contained in Y ¹² may be substituted with a halogen atom.

Specific examples of compounds represented by formula (XI) include those described in JP-A No. 7-281028, paragraphs 0028-0036, JP-A No. 7-306317, JP-A No. 2005-156822, paragraphs 0016-0018, JP-A No. 2006-301614, paragraphs 0067-0072, and pp. 330-333 of the Liquid Crystal Handbook (published by Maruzen Co., Ltd. in 2000), in which at least one (preferably three or more) of the terminal groups is an epoxy group.

The compound represented by formula (XI) can be synthesized in accordance with the methods described in JP-A-7-306317, JP-A-7-281028, JP-A-2005-156822, and JP-A-2006-301614.

In addition, from the viewpoint of achieving better thermal conductivity of the thermal conductive material, compounds represented by formula (D16) are also preferred as discotic compounds.

In formula (D16), A ^2X , A ^3X , and A ^4X each independently represent -CH= or -N=. Among these, it is preferable that A ^2X , A ^3X , and A ^4X are all -CH= or all -N=. In other words, it is preferable that the 6-membered ring (central ring) containing A ^2X , A ^3X , and A ^4X is a benzene ring or a triazine ring.
R ^17X , R ^18X and R ^19X each independently represent *-X ^211X -(Z ^21X -X ^212X ) _n21X -L ^21X -Q, where * represents the bonding position to the central ring.
X ^211X and X ^212X each independently represent a single bond, -O-, -CO-, -NH-, -O-CO-, -O-CO-O-, -O-CO-NH-, -O-CO-S-, -CO-O-, -CO-NH-, -CO-S-, -NH-CO-, -NH-CO-O-, -NH-CO-NH-, -NH-CO-S-, -S-, -S-CO-, -S-CO-O-, -S-CO-NH-, or -S-CO-S-.
Z ^21X each independently represents a 5- or 6-membered aromatic ring group, or a 5- or 6-membered non-aromatic ring group.
L ^21X represents a single bond or a divalent linking group.
Q has the same definition as Q in formulas (D1) to (D15), and the preferred conditions are also the same. In formula (D16), of the multiple Qs, at least one (preferably all) Qs represent an epoxy group.
n21X represents an integer of 0 to 3. When n21X is 2 or greater, the multiple (Z ^21X -X ^212X ) may be the same or different.

As the compound represented by formula (D16), a compound represented by formula (XII) is preferred.

In formula (XII), A ² , A ³ , and A ⁴ each independently represent -CH= or -N=. In particular, it is preferable that A ² , A ³ , and A ⁴ are all -CH= or all -N=. In other words, it is preferable that the 6-membered ring (central ring) containing A ² , A ³ , and A ⁴ is a benzene ring or a triazine ring.

R ¹⁷ , R ¹⁸ and R ¹⁹ each independently represent *-X ²¹¹ -(Z ²¹ -X ²¹² ) _n21 -L ²¹ -P ²¹ or *-X ²²¹ -(Z ²² -X ²²² ) _n22 -Y ^22. * represents the bonding position to the central ring.
Two or more of R ¹⁷ , R ¹⁸ and R ¹⁹ are *-X ²¹¹ -(Z ²¹ -X ²¹² ) _n21 -L ²¹ -P ^21. From the viewpoint of achieving better thermal conductivity of the thermal conductive material, it is preferable that all of R ¹⁷ , R ¹⁸ and R ¹⁹ are *-X ²¹¹ -(Z ²¹ -X ²¹² ) _n21 -L ²¹ -P ²¹ .
In addition, it is preferred that R ¹⁷ , R ¹⁸ and R ¹⁹ are all the same.

X ²¹¹ , X ²¹² , X ²²¹ and X ²²² each independently represent a single bond, -O-, -CO-, -NH-, -O-CO-, -O-CO-O-, -O-CO-NH-, -O-CO-S-, -CO-O-, -CO-NH-, -CO-S-, -NH-CO-, -NH-CO-O-, -NH-CO-NH-, -NH-CO-S-, -S-, -S-CO-, -S-CO-O-, -S-CO-NH- or -S-CO-S-.
Among these, X ²¹¹ , X ²¹² , X ²²¹ and X ²²² are each preferably independently a single bond, —NH—, —O—, —CO—O— or —O—CO—.

Z ²¹ and Z ²² each independently represent a 5- or 6-membered aromatic ring group or a 5- or 6-membered non-aromatic ring group, examples of which include a benzene ring group (such as a 1,4-phenylene group or a 1,3-phenylene group) and an aromatic heterocyclic group.

The aromatic ring group and the non-aromatic ring group may have a substituent. When they have a substituent, the number of the substituents is preferably 1 to 4, more preferably 1 or 2, and even more preferably 1. The substitution position of the substituent is not particularly limited. The substituent is preferably a halogen atom or a methyl group. It is also preferable that the aromatic ring group and the non-aromatic ring group are unsubstituted. Furthermore, they may further have a group represented by "-X ²¹² -L ²¹ -P ²¹ " as a substituent.

Examples of the aromatic heterocyclic group include the following aromatic heterocyclic groups.

In the formula, * represents a site bonding to X ²¹¹ or X ^221. ** represents a site bonding to X ²¹² or X ^{222. A 41} and A ⁴² each independently represent a methine group or a nitrogen atom. X ⁴ represents an oxygen atom, a sulfur atom, or an imino group.
At least one of A ⁴¹ and A ⁴² is preferably a nitrogen atom, and more preferably both are nitrogen atoms. X ⁴ is preferably an oxygen atom.

When n21 and n22 described below are 2 or greater, a plurality of (Z ²¹ -X ²¹² ) and a plurality of (Z ²² -X ²²² ) may be the same or different.

L ²¹ each independently represents a single bond or a divalent linking group and has the same meaning as L ¹¹ in formula (XI) above. L ²¹ is preferably -O-, -O-CO-, -CO-O-, -S-, -NH-, an alkylene group (preferably having 1 to 10 carbon atoms, more preferably having 1 to 8 carbon atoms, and even more preferably having 1 to 7 carbon atoms), an arylene group (preferably having 6 to 20 carbon atoms, more preferably having 6 to 14 carbon atoms, and even more preferably having 6 to 10 carbon atoms), or a group formed from a combination thereof.

When n22 described below is 1 or greater, examples of -X ²¹² -L ²¹ - include L101 to L143, which are examples of L in the above formulae (D1) to (D15), except that in this case, the left bond in L101 to L143 is bonded to the central structure of the compound (hereinafter also simply referred to as the "central ring"), and the right bond is bonded to ^P21 .

^P21 represents an epoxy group, which may or may not have a substituent.

Y ²² each independently represents a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, or a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms in which one or more methylene groups have been substituted with -O-, -S-, -NH-, -N(CH ₃ )-, -CO-, -O-CO-, or -CO-O-, and has the same meaning as Y ¹² in general formula (XI), and the preferred range is also the same.

n21 and n22 each independently represent an integer of 0 to 3, and from the viewpoint of more excellent thermal conductivity, an integer of 1 to 3 is preferable. In particular, when A ² , A ³ , and A ⁴ are all -CH=, it is more preferable that n21 and n22 each independently represent an integer of 2 to 3, and when A ² , A ³ , and A ⁴ are all -N=, it is more preferable that n21 and n22 each independently represent 1.

Preferred examples of discotic compounds include the following compounds:

In the following structural formula, R represents —X ²¹² -L ²¹ -P ²¹ .

For details and specific examples of the compound represented by formula (XII), please refer to the compounds described in paragraphs 0013 to 0077 of JP 2010-244038 A, in which at least one (preferably three or more) of the terminal groups is an epoxy group, the contents of which are incorporated herein by reference.

The compound represented by formula (XII) can be synthesized in accordance with the methods described in JP-A-2010-244038, JP-A-2006-076992, and JP-A-2007-002220.

In addition, from the perspective of reducing electron density, strengthening stacking, and facilitating the formation of columnar aggregates, it is also preferable that the discotic compound is a compound having a hydrogen-bonding functional group. Examples of hydrogen-bonding functional groups include -O-CO-NH-, -CO-NH-, -NH-CO-, -NH-CO-O-, -NH-CO-NH-, -NH-CO-S-, and -S-CO-NH-.

(Other epoxy compounds)
In addition to the above-mentioned epoxy compounds, compounds represented by the general formula (Z), general formula (Z1), or general formula (Z2) described in the description of the phenolic compounds in which the phenolic hydroxyl group is replaced with an epoxy-containing group can also be used as the epoxy compound.
The epoxy-containing group is a group that is an epoxy group itself, or a monovalent group that partially contains an epoxy group.
The monovalent group partially containing an epoxy group is a group having one or more (preferably 1 to 8) epoxy groups within the entire group.
The monovalent group partially containing an epoxy group is preferably a group represented by "-(divalent hydrocarbon group) _M1 -(-O-divalent hydrocarbon group-) _M2 -epoxy group". In the above group, M1 represents 0 or 1. M2 represents an integer of 1 or more (preferably 1 to 10). Examples of the divalent hydrocarbon group in the above group include alkylene groups (preferably having 1 to 6 carbon atoms), alkenylene groups (-CH=CH-, etc., preferably having 2 to 6 carbon atoms), alkynylene groups (-C≡C-, etc., preferably having 2 to 6 carbon atoms), arylene groups (phenylene group, etc., preferably having 6 to 15 carbon atoms), and combinations thereof. The divalent hydrocarbon group may or may not have a substituent, and the divalent hydrocarbon group may further have an epoxy-containing group as a substituent. A plurality of the divalent hydrocarbon groups may be present and may be the same or different.

Other epoxy compounds include, for example, epoxy compounds represented by general formula (DN):

In formula (DN), n ^DN represents an integer of 0 or more, preferably an integer of 0 to 5, and more preferably 1.
R ^DN represents a single bond or a divalent linking group. The divalent linking group is preferably —O—, —O—CO—, —CO—O—, —S—, an alkylene group (preferably having 1 to 10 carbon atoms), an arylene group (preferably having 6 to 20 carbon atoms), or a group formed from a combination thereof, more preferably an alkylene group, and more preferably a methylene group.

Other epoxy compounds include epoxy compounds represented by general formula (E2).
(V-) _4-U C(-W) _U (E2)

In general formula (E2), C represents a carbon atom.

In formula (E2), U represents an integer of 3 or 4.
In general formula (E2), the "U" in "4-U" indicating the number of Vs and the "U" indicating the number of Ws have the same value. In other words, general formula (E2) is "VC(-W) ₃ " or "C(-W) ₄ ".

In general formula (E2), V represents a substituent not having an epoxy group or a hydrogen atom.
The substituent not having an epoxy group is a substituent other than an epoxy group, and does not contain an epoxy group even as a part of the substituent.
Examples of the substituent not having an epoxy group include groups selected from the substituent group Y, excluding epoxy groups and groups partially containing an epoxy group.
The substituent not having an epoxy group is preferably an alkyl group, more preferably a linear or branched alkyl group, and preferably has 1 to 5 carbon atoms.

In formula (E2), W represents an epoxy-containing group.
The epoxy-containing group is a group that is an epoxy group itself, or a monovalent group that partially contains an epoxy group.
The monovalent group partially containing an epoxy group is a group having one or more (preferably 1 to 8) epoxy groups within the entire group.
The monovalent group partially containing an epoxy group is preferably a group represented by "-(divalent hydrocarbon group) _M1 -(-O-divalent hydrocarbon group-) _M2 -epoxy group". In the above group, M1 represents 0 or 1. M2 represents an integer of 1 or more (preferably 1 to 10). Examples of the divalent hydrocarbon group in the above group include alkylene groups (preferably having 1 to 6 carbon atoms), alkenylene groups (-CH=CH-, etc., preferably having 2 to 6 carbon atoms), alkynylene groups (-C≡C-, etc., preferably having 2 to 6 carbon atoms), arylene groups (phenylene group, etc., preferably having 6 to 15 carbon atoms), and combinations thereof. The divalent hydrocarbon group may or may not have a substituent, and the divalent hydrocarbon group may further have an epoxy-containing group as a substituent. A plurality of the divalent hydrocarbon groups may be present, and may be the same or different.
A plurality of Ws present in general formula (E2) may be the same or different.

Other epoxy compounds include compounds in which the epoxy group is fused to a ring. Examples of such compounds include 3,4:8,9-diepoxybicyclo[4.3.0]nonane.

Other epoxy compounds include those represented by general formula (E3).
Epoxy group —CH ₂ —O—(alkylene group —O) _X —CH ₂ -epoxy group (E3)
In formula (E3), X represents an integer of 1 or more, preferably an integer of 1 to 50, more preferably an integer of 1 to 15, and even more preferably an integer of 1 to 3.
The alkylene group in general formula (E3) may be linear or branched. The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 2 or 3, and even more preferably 2. When a plurality of alkylene groups are present in general formula (E3), the plurality of alkylene groups may be the same or different.

Other epoxy compounds include, for example, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, bisphenol AD type epoxy compounds, etc., which are glycidyl ethers of bisphenol A, F, S, AD, etc.; hydrogenated bisphenol A type epoxy compounds, hydrogenated bisphenol AD type epoxy compounds, etc.; phenol novolac type glycidyl ethers (phenol novolac type epoxy compounds), cresol novolac type glycidyl ethers (cresol novolac type epoxy compounds), bisphenol A novolac type glycidyl ethers (cresol novolac type epoxy compounds), ethers, etc.; dicyclopentadiene-type glycidyl ethers (dicyclopentadiene-type epoxy compounds); dihydroxypentadiene-type glycidyl ethers (dihydroxypentadiene-type epoxy compounds); polyhydroxybenzene-type glycidyl ethers (polyhydroxybenzene-type epoxy compounds) such as glycidyl ethers of dihydroxybenzenes such as resorcinol; benzenepolycarboxylic acid-type glycidyl esters (benzenepolycarboxylic acid-type epoxy compounds); trisphenolmethane-type epoxy compounds; phenoxy resins, etc.; and acrylic resins having epoxy groups in their side chains. Compounds in which one or more of the glycidyl ether groups and/or glycidyl ester groups in the above-mentioned compounds are replaced with diglycidylamino groups or diglycidylaminoalkylene groups (diglycidylaminomethylene groups, etc.) may also be used as the epoxy compound.
Each of the above compounds may have a substituent. For example, the aromatic ring group, cycloalkane ring group, and/or alkylene group contained in each of the above compounds may have a substituent other than a glycidyl ether group, a glycidyl ester group, a diglycidylamino group, and/or a diglycidylaminoalkylene group.

The epoxy compound preferably comprises at least one selected from the group consisting of polyhydroxybenzene-type glycidyl ethers, bisphenol F-type glycidyl ethers, epoxy compounds represented by general formula (DN), rod-shaped compounds (preferably rod-shaped compounds having a biphenyl skeleton), discotic compounds (preferably discotic compounds having a biphenylene ring as a central ring, a triazine ring as a central ring, or a benzene ring as a central ring), phenol novolac-type glycidyl ethers, phenoxy resins, epoxy compounds represented by general formula (E2), and epoxy compounds represented by general formula (E3).
When the epoxy compound contains these compounds, the content thereof is more than 0 mass % and 100 mass % or less, preferably 30 to 100 mass %, more preferably 60 to 100 mass %, and still more preferably 90 to 100 mass %, relative to the total mass of the epoxy compound.

It is also preferable that the epoxy compound includes an epoxy compound having a viscosity of less than 1000 mPa·s at 25° C. (also referred to as a “low-viscosity epoxy compound”).
In particular, when the composition contains a maleimide compound described below, the epoxy compound preferably contains the low-viscosity epoxy compound.
When the epoxy compound contains a low-viscosity epoxy compound, flexibility is introduced into the semi-cured film formed from the composition, improving storage stability and improving the handleability of the semi-cured film after a certain period of time has elapsed since its formation. Such an improvement effect is particularly remarkable when the composition contains a maleimide compound described below.
The viscosity of the low-viscosity epoxy compound at 25° C. is less than 1000 mPa·s, preferably 500 mPa·s or less, and more preferably 300 mPa·s or less. The lower limit of the viscosity is not particularly limited, but is, for example, 1 mPa·s or more.
The viscosity of the epoxy compound is measured at 25°C using a RheoStress RS6000 (manufactured by Eiko Seiki Co., Ltd.) and is the value obtained by reading the value 1 minute after the start of the measurement. The shear rate is 10 (1/s).

When the epoxy compound contains a low-viscosity epoxy compound, the content of the low-viscosity epoxy compound is preferably 5 to 100 mass%, more preferably 20 to 100 mass%, and even more preferably 60 to 100 mass%, based on the total amount of the epoxy compounds.
As the low-viscosity epoxy compound, for example, an epoxy compound having a predetermined viscosity among the above-mentioned epoxy compounds can be used. More specific examples include bisphenol F-type glycidyl ethers, epoxy compounds represented by general formula (E3) in which X is an integer of 1 to 13, and dihydroxybenzene-type glycidyl ethers.

[Relationship between phenolic compounds and epoxy compounds]
In the composition of the present invention containing an epoxy compound, it is preferable that at least one of the following requirements be satisfied: the phenol compound contains a phenol compound having a triazine skeleton (requirement 1), and the epoxy compound contains an epoxy compound having a triazine skeleton (requirement 2).
The composition may satisfy only requirement 1, may satisfy only requirement 2, or may satisfy both requirements 1 and 2.

The phenol compound and epoxy compound "having a triazine skeleton" means that the compound has one or more (for example, 1 to 5) triazine ring groups.
Examples of the phenol compound having a triazine skeleton include the compounds represented by general formula (Z), general formula (Z1), and general formula (Z2) described above.
Examples of epoxy compounds having a triazine skeleton include the above-mentioned compounds represented by formula (D16) in which A ^2X , A ^3X , and A ^4X are all —N=, compounds represented by formula (XII) in which A ² , A ³ , and A ⁴ are all —N=, compounds represented by the general formula (Z) in which the phenolic hydroxyl group is replaced with an epoxy-containing group, compounds represented by the general formula (Z1) in which the phenolic hydroxyl group is replaced with an epoxy-containing group, and compounds represented by the general formula (Z2) in which the phenolic hydroxyl group is replaced with an epoxy-containing group.

When the phenol compound contains a phenol compound having a triazine skeleton (for example, when requirement 1 is satisfied), the content thereof is more than 0 mass % and not more than 100 mass %, preferably 30 to 100 mass %, more preferably 60 to 100 mass %, and even more preferably 90 to 100 mass %, relative to the total mass of the phenol compounds. Note that when the composition contains an epoxy compound, and the epoxy compound contains an epoxy compound having a triazine skeleton (that is, when requirement 2 is satisfied), the content of the phenol compound having a triazine skeleton is also preferably outside the above-mentioned preferred range.
When the composition contains an epoxy compound, and the epoxy compound contains an epoxy compound having a triazine skeleton (i.e., when requirement 2 is satisfied), the content thereof is more than 0 mass % and not more than 100 mass %, preferably 30 to 100 mass %, more preferably 60 to 100 mass %, and even more preferably 90 to 100 mass %, relative to the total mass of the epoxy compounds. Note that when the phenol compound contains a phenol compound having a triazine skeleton (i.e., when requirement 1 is satisfied), the content of the epoxy compound having a triazine skeleton may be outside the above-mentioned preferred range.

When the composition contains an epoxy compound, it is also preferred that at least a part of the phenol compound and the epoxy compound is a compound other than a compound having a triazine skeleton.
All or part of the phenol compound may be a compound other than a triazine skeleton, and all or part of the epoxy compound may be a compound other than a triazine skeleton.
When the composition contains an epoxy compound, from the viewpoint of adjusting the crosslink density and further improving the effects of the present invention, the total content of the phenol compound having a triazine skeleton and the epoxy compound having a triazine skeleton is preferably more than 0 mass% and less than 100 mass%, more preferably 1 to 90 mass%, and still more preferably 5 to 80 mass%, based on the total content of all phenol compounds and all epoxy compounds.

Furthermore, the total content of the epoxy compound and the phenol compound in the composition is preferably 3 to 90 mass %, more preferably 5 to 50 mass %, and even more preferably 7 to 40 mass %, based on the total solid content of the composition.
The epoxy compounds and/or phenol compounds may be used alone or in combination of two or more.

In the composition, the ratio of the total number of epoxy groups contained in the epoxy compound to the total number of hydroxyl groups (preferably phenolic hydroxyl groups) contained in the phenol compound (number of epoxy groups/number of hydroxyl groups) is usually 3/97 to 97/3, preferably 30/70 to 70/30, more preferably 40/60 to 60/40, and even more preferably 45/55 to 55/45.
In other words, the ratio of the contents of the phenol compound and the epoxy compound in the composition is preferably such that the "number of epoxy groups/number of phenolic hydroxyl groups" falls within the above range.

In addition, in the composition, the equivalent ratio (number of epoxy groups/number of active hydrogens) of the epoxy groups of the epoxy compound to the active hydrogens (which may be active hydrogens derived from phenolic hydroxyl groups or active hydrogens of other active hydrogen-containing compounds) is typically 3/97 to 97/3, preferably 30/70 to 70/30, more preferably 40/60 to 60/40, and even more preferably 45/55 to 55/45.

In the composition, the ratio of the total number of epoxy groups contained in the epoxy compound to the total number of hydroxyl groups (preferably phenolic hydroxyl groups) contained in the phenol compound (number of epoxy groups/number of hydroxyl groups) is preferably 1.1/1.0 to 3.0/1.0, more preferably 1.2/1.0 to 2.0/1.0, and even more preferably 1.3/1.0 to 1.8/1.0. In other words, the ratio of the total number of epoxy groups contained in the epoxy compound to the total number of hydroxyl groups (preferably phenolic hydroxyl groups) contained in the phenol compound (number of epoxy groups/number of hydroxyl groups) is preferably 1.1 to 3.0, more preferably 1.2 to 2.0, and even more preferably 1.3 to 1.8.
In particular, when the composition contains a maleimide compound described below, it is preferable that the ratio falls within the above range.
When the ratio is equal to or greater than a predetermined value, flexibility is introduced into the semi-cured film formed from the composition, improving storage stability, and the semi-cured film has good handleability even after a certain period of time has passed since its formation. When the ratio is equal to or less than a predetermined value, the heat resistance of the thermal conductive material formed from the composition is superior. Such an improvement effect is particularly significant when the composition contains a maleimide compound described below.

The composition may contain little or no epoxy compounds. In this case, the ratio of the total number of epoxy groups contained in the epoxy compounds to the number of hydroxyl groups (preferably phenolic hydroxyl groups) contained in the phenolic compounds in the composition (number of epoxy groups/number of hydroxyl groups) is, for example, 0/100 or more and less than 3/97 (preferably 0/100 or more and less than 1/99 (0 or more and less than 0.031, preferably 0 or more and less than 0.011)).

[Specific compound]
The composition includes a specific compound.
The specific compound is a general term for a maleimide compound having one or more maleimide groups and a cyanate compound having one or more cyanate groups.
That is, the composition contains one or both of a maleimide compound and a cyanate compound.

In this specification, compounds having both maleimide groups and cyanate groups are classified as follows: if the compound has more maleimide groups than cyanate groups, the compound is classified as a maleimide compound; if the compound has more cyanate groups than maleimide groups, the compound is classified as a cyanate compound; and if the number of maleimide groups and cyanate groups is the same, the compound is classified as a maleimide compound.

The total content of the specific compounds is preferably from 0.1 to 40% by mass, more preferably from 1 to 25% by mass, and even more preferably from 3.5 to 15% by mass, based on the total solid content of the composition.
The total content of the specific compounds is preferably 5 to 200 mass%, more preferably 10 to 180 mass%, and even more preferably 20 to 160 mass%, based on the total content of the epoxy compound and the phenol compound. When the composition does not contain an epoxy compound, the total content refers to the content of the phenol compound alone.
It is also preferable that the composition substantially contains only one of the maleimide compound and the cyanate compound. In this case, for example, the content of one of the maleimide compound and the cyanate compound is preferably more than 98 mass% and 100 mass% or less, more preferably 99 to 100 mass%, and even more preferably 99.9 to 100 mass%, relative to the total mass of the specific compounds.
When the composition contains both a maleimide compound and a cyanate compound, the mass ratio of the cyanate compound to the maleimide compound in the composition (mass of cyanate compound/mass of maleimide compound) is preferably 2/98 to 98/2, more preferably 70/30 to 70/30, and even more preferably 40/60 to 60/40.

<Maleimide Compound>
It is also preferable that the composition contains at least a maleimide compound among the specific compounds.
A maleimide compound is a compound having one or more maleimide groups.

The number of maleimide groups contained in the maleimide compound is 1 or more, preferably 1 to 100, more preferably 2 to 10, and even more preferably 2.
The maleimide compound may be a high molecular weight compound or a low molecular weight compound.
For example, the molecular weight of the maleimide compound is preferably 100 to 3,000, more preferably 200 to 2,000, and even more preferably 300 to 1,000.

The maleimide group possessed by the maleimide compound is preferably a group represented by the following general formula (M):

In formula (M), * represents a bonding position.
X and Y each independently represent a hydrogen atom or a substituent.
X and Y are each preferably a hydrogen atom.

The maleimide compound is also preferably a compound having one or more (preferably 1 to 10) aromatic ring groups (such as benzene ring groups).
Among them, the maleimide compound is preferably a compound represented by the following general formula (1):

In formula (1), m represents 0 or 1. Preferably, m is 1.
n represents 0 or 1. n is preferably 1.

In general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituent.
The substituent is preferably an alkyl group, which may be linear or branched and preferably has 1 to 10 carbon atoms.
When R ¹ and/or R ² are substituents, they are preferably located adjacent to the maleimide group on the benzene ring group, for example.
When R ¹ and R ² are both substituents, it is also preferable that R ¹ and R ² are different substituents. For example, it is also preferable that R ¹ is a methyl group and R ² is an ethyl group.

In formula (1), ^L1 represents a divalent linking group.
Examples of the divalent linking group include an ether group (-O-), a carbonyl group (-CO-), an ester group (-COO-), a thioether group (-S-), -SO ₂ -, -NR- (R is a hydrogen atom or an alkyl group), a divalent aliphatic hydrocarbon group (for example, an alkylene group, a cycloalkylene group, an alkenylene group (-CH=CH-, etc.), an alkynylene group (-C≡C-, etc.)), a divalent aromatic ring group (an arylene group and a heteroarylene group), and a group formed by combining these.
In general formula (1), L ¹ preferably has 1 or more carbon atoms, more preferably 1 to 100 carbon atoms, and even more preferably 3 to 15 carbon atoms.

Among these, L ¹ is preferably a group represented by "* ^p- (L ² -Ar) _k- * ^q ".
* ^q represents the bonding position on the side directly bonded to the maleimide group, and * ^p represents the bonding position on the opposite side.
k represents an integer of 1 or more, preferably 1 to 10, and more preferably 1.
L ² represents a single bond, —C(R ³ )(R ⁴ )—, —O—, or —CO—, and —C(R ³ )(R ⁴ )— is preferred.
^R3 and ^R4 each independently represent a hydrogen atom or a substituent, and are preferably an alkyl group (which may be linear or branched and has, for example, 1 to 10 carbon atoms).
Ar represents an arylene group. The number of ring atoms in the arylene group is preferably 6 to 15, and more preferably 6. When the arylene group has a substituent, the number of the substituent is preferably 1 to 4, and more preferably 1 or 2. The substituent that the arylene group may have is preferably an alkyl group (which may be linear or branched, and has, for example, 1 to 10 carbon atoms). Examples of structures that Ar can have include structures that can be formed by the benzene ring group bonded to ^R1 and ^R2 , as specified in general formula (1).
When a plurality ^{of L2s} and a plurality of Ars are present, the plurality of ^L2s and the plurality of Ars may be the same or different.

In the general formula (1) when n is 1, on the benzene ring group bonding to ^R1 and ^R2 , the two groups, the maleimide group and the group represented by "-( ^L1 ) _m -maleimide group", may be located at the ortho position, the meta position, or the para position relative to each other. Of these, it is preferable that the two groups are located at the meta position or the para position.

In particular, it is preferable that the compound represented by general formula (1) has m=1, n=1, and the divalent linking group represented by ^L1 has 3 to 15 carbon atoms.

The maleimide compound may be used alone or in combination of two or more kinds.
The content of the maleimide compound is preferably 0.1 to 40 mass%, more preferably 1 to 15 mass%, and even more preferably 3.5 to 8 mass%, relative to the total solid content of the composition, and from the viewpoint of better handleability of a semi-cured film formed from the composition, it is still more preferably 3.5 to 8 mass%.
In addition, from the viewpoint of obtaining a thermally conductive material having better thermal conductivity and/or insulating properties, it is also preferable that the content of the maleimide compound is 6% by mass or more (for example, 6 to 12% by mass) relative to the total solid content of the composition.
When the composition contains an epoxy compound, the content of the maleimide compound is, for example, 1 to 200 mass%, preferably 5 to 100 mass%, more preferably 10 to 70 mass%, and still more preferably 20 to 60 mass%, relative to the total content of the epoxy compound and the phenol compound.
The content of the maleimide compound is, for example, 1 to 500% by mass, preferably 20 to 300% by mass, more preferably 50 to 200% by mass, and even more preferably 70 to 130% by mass, relative to the content of the phenol compound.

<Cyanate Compound>
It is also preferable that the composition contains at least a cyanate compound among the specific compounds.
A cyanate compound is a compound having one or more cyanate groups (-OCN).

The number of cyanate groups contained in the cyanate compound is 1 or more, preferably 1 to 100, and more preferably 2 to 50.
The cyanate compound may be a high molecular weight compound or a low molecular weight compound.
For example, the molecular weight of the cyanate compound is preferably 100 to 3,000, more preferably 200 to 2,000, and even more preferably 300 to 1,000.

The cyanate compound is also preferably a compound having one or more (preferably 1 to 10) aromatic ring groups (such as benzene ring groups).
Among them, the cyanate compound is preferably a compound represented by the following general formula (2).

In the general formula (2), nc represents an integer of 0 or more.
nc is preferably an integer of 0 to 100.

In formula (2), ^Lc represents a single bond or a divalent linking group.
Examples of the divalent linking group include an ether group (-O-), a carbonyl group (-CO-), an ester group (-COO-), a thioether group (-S-), -SO ₂ -, -NR- (R is a hydrogen atom or an alkyl group), a divalent aliphatic hydrocarbon group (for example, an alkylene group, a cycloalkylene group, an alkenylene group (-CH=CH-, etc.), an alkynylene group (-C≡C-, etc.)), a divalent aromatic ring group (an arylene group and a heteroarylene group), and a group formed by combining these.
Among these, the divalent linking group is preferably an alkylene group, a cycloalkylene group, or a thioether group.
The alkylene group may be linear or branched, and preferably has 1 to 8 carbon atoms. Of these, the alkylene group is preferably -C(R ^A )(R ^B )-. ^{R A} and R ^B each independently represent a hydrogen atom, a halogen atom, or an alkyl group. The alkyl group may be linear or branched, and preferably has 1 to 3 carbon atoms. A substituent that the alkyl group may have is preferably a halogen atom, more preferably a fluorine atom. It is also preferable that the alkyl group is a perfluoroalkyl group.
The cycloalkylene group may be monocyclic or polycyclic, and preferably has a carbon number of 3 to 20. The cycloalkylene group is preferably a tetrahydrodicyclopentadiene ring group.
In general formula (2), when a plurality of ^Lc 's are present, the plurality of ^Lc's may be the same or different.

In formula (2), Ar ^c represents an aromatic ring group.
The aromatic ring group may be monocyclic or polycyclic, and preferably has 5 to 20 ring atoms.
The aromatic ring group may be an aromatic hydrocarbon ring group or an aromatic heterocyclic group, with an aromatic hydrocarbon ring group being preferred.
Among these, the aromatic ring group is preferably a benzene ring group.
The aromatic ring group may have one or more (for example, 1 to 4) substituents other than the cyanate group (—OCN) shown in general formula (2). The substituent is preferably an alkyl group (which may be linear or branched and preferably has 1 to 3 carbon atoms).
Furthermore, the general formula (2) may further have a cyanate group as a substituent other than the cyanate group (—OCN).
In general formula (2), when a plurality of Ar ^c's are present, the plurality of Ar ^c's may be the same or different.

The cyanate compound may be a prepolymerized product, for example, a prepolymerized product of the compound represented by the above general formula (2).
The term "preliminary polymer" as used herein refers to a cyanate compound in a prepolymer state obtained by polymerizing cyanate compounds (preferably compounds represented by the above general formula (2)) to a certain extent and then terminating the reaction.

As the cyanate compound, for example, the compounds exemplified below and prepolymers of one or more compounds selected from the compounds exemplified below can be used.
In the following examples, n represents an integer of 1 or more.

As the cyanate compound, commercially available products may be used.
Commercially available products include, for example, CYTESTER TA, TA-100, TA-1500, and P-201 (all manufactured by Mitsubishi Gas Chemical Company, Inc.), and AROCY XU371 (manufactured by Huntsman).

The cyanate compound may be used alone or in combination of two or more.
The content of the cyanate compound is preferably from 0.1 to 40% by mass, more preferably from 1 to 15% by mass, and even more preferably from 3.5 to 10% by mass, based on the total solid content of the composition.
When the composition contains an epoxy compound, the content of the cyanate compound is, for example, 1 to 300 mass%, preferably 5 to 250 mass%, more preferably 10 to 200 mass%, and even more preferably 20 to 150 mass%, relative to the total content of the epoxy compound and the phenol compound.
The content of the cyanate compound is, for example, 1 to 600 mass %, preferably 20 to 500 mass %, more preferably 50 to 400 mass %, and even more preferably 70 to 300 mass %, relative to the content of the phenol compound.

[Inorganic substances]
The composition includes an inorganic material.
The inorganic substance may be used alone or in combination of two or more kinds.
As the inorganic substance, any inorganic substance that has been used as an inorganic filler in conventional thermally conductive materials may be used.
The inorganic material includes at least an inorganic nitride (preferably boron nitride).
The inorganic material may further include an inorganic oxide (preferably aluminum oxide) in addition to the inorganic nitride.

The shape of the inorganic material is not particularly limited and may be particulate, film-like, or plate-like. Examples of the shape of particulate inorganic material include rice grain-like, spherical, cubic, spindle-like, scale-like, aggregated, and irregular shapes.

The size of the inorganic substance is not particularly limited, but in terms of better dispersibility of the inorganic substance, the average particle size of the inorganic substance is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. The lower limit is not particularly limited, but in terms of handleability, it is preferably 10 nm or more, more preferably 100 nm or more.
When a commercially available product is used, the average particle size of the inorganic substance is determined by the catalog value. If no catalog value is available, the average particle size is determined by randomly selecting 100 inorganic substances using an electron microscope, measuring the particle size (major axis) of each inorganic substance, and calculating the arithmetic average.

In order to achieve better thermal conductivity of the thermal conductive material, it is preferable that the composition contains at least an inorganic substance (preferably an inorganic nitride or inorganic oxide, more preferably an inorganic nitride, even more preferably boron nitride, and particularly preferably agglomerated boron nitride) with an average particle size of 20 μm or more (preferably 30 μm or more).

Examples of inorganic nitrides, which are a type of inorganic substance, include boron nitride (BN), carbon nitride (C ₃ N ₄ ), silicon nitride (Si ₃ N ₄ ), gallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN), chromium nitride (Cr ₂ N), copper nitride (Cu ₃ N), iron nitride (Fe ₄ N), iron nitride (Fe ₃ N), lanthanum nitride (LaN), lithium nitride (Li ₃ N), magnesium nitride (Mg ₃ N ₂ ), molybdenum nitride (Mo ₂ N), niobium nitride (NbN), tantalum nitride (TaN), titanium nitride (TiN), tungsten nitride (W ₂ N), tungsten nitride (WN ₂ ), yttrium nitride (YN), and zirconium nitride (ZrN).
The inorganic nitrides may be used alone or in combination of two or more.
The inorganic nitride preferably contains aluminum atoms, boron atoms, or silicon atoms, more preferably aluminum nitride, boron nitride, or silicon nitride, even more preferably aluminum nitride or boron nitride, and particularly preferably boron nitride. Most preferably, the boron nitride contains at least aggregated boron nitride particles having an average particle size of 20 μm or more.
The content of the inorganic nitride (preferably boron nitride and/or aluminum nitride, more preferably aggregated boron nitride having an average particle size of 20 μm or more) in the inorganic substance is preferably 10 to 100 mass %, more preferably 40 to 100 mass %, and even more preferably 60 to 100 mass %, relative to the total mass of the inorganic substance.

Examples of inorganic oxides, which are a type of inorganic substance, include zirconium oxide ( _ZrO2 ), titanium oxide ( _TiO2 ), silicon oxide ( _SiO2 ), aluminum oxide ( _Al2O3 ), iron _{oxide (Fe2O3 , FeO, Fe3O4 ) ,} copper oxide (CuO, _Cu2O ), zinc oxide ( _ZnO ), yttrium oxide ( _Y2O3 ), niobium oxide ( _Nb2O5 ), molybdenum oxide ( _MoO3 ), indium oxide ( _In2O3 , _In2O ), tin oxide ( _SnO2 ), tantalum _{oxide ( Ta2O5} ), tungsten oxide ( _WO3 , _W2O5 ), lead oxide (PbO, _PbO2 ), bismuth oxide ( _Bi2O3 ), _and cerium oxide ( _{CeO2 ) .} , Ce ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ), germanium oxide (GeO ₂ , GeO), lanthanum oxide (La ₂ O ₃ ), and ruthenium oxide (RuO ₂ ).
It is also preferable that the inorganic oxide is different from the inorganic ion scavenger described below.
The inorganic oxides may be used alone or in combination of two or more.
The inorganic oxide is preferably titanium oxide, aluminum oxide (alumina), or zinc oxide, and more preferably aluminum oxide.
The inorganic oxide may be an oxide that is produced when a metal prepared as a non-oxide is oxidized under environmental conditions.

The inorganic substance may include an inorganic substance that falls under the category of an ion scavenger (an inorganic ion scavenger).
Examples of inorganic ion trapping agents include inorganic ion trapping agents such as cation adsorbents that trap cations by ion exchange, anion adsorbents that trap anions by ion exchange, and amphoteric ion trapping agents that trap both cations and anions by ion exchange.

Examples of inorganic ion scavengers include inorganic substances (preferably composite inorganic substances) containing one or more (preferably two or more) selected from the group consisting of antimony, bismuth, zirconium, titanium, tin, and magnesium. Examples of inorganic substances (preferably composite inorganic substances) containing one or more (preferably two or more) of the above elements include oxides (preferably composite oxides), oxide hydrates (preferably composite oxide hydrates), and hydroxides (preferably composite hydroxides).
Other examples of inorganic ion scavengers include composite inorganic materials (composite oxides, composite oxide hydrates, composite hydroxides, etc.) of aluminum and one or more elements selected from the group consisting of antimony, bismuth, zirconium, titanium, tin, and magnesium.
An example of the composite oxide is an aluminum oxide/magnesium oxide solid solution.

The inorganic ion scavenger, which is a composite, is preferably an oxide (composite oxide), oxide hydrate (composite oxide hydrate), or hydroxide (composite hydroxide) of two or more elements selected from the group consisting of antimony, bismuth, zirconium, magnesium, and aluminum.
Among these, the inorganic ion scavenger is preferably a ternary composite of magnesium, aluminum, and zirconium (composite oxide, composite oxide hydrate, composite hydroxide, etc.), a binary composite of bismuth and zirconium (composite oxide, composite oxide hydrate, composite hydroxide, etc.), a binary composite of bismuth and antimony (composite oxide, composite oxide hydrate, composite hydroxide, etc.), or a composite containing magnesium and aluminum (composite oxide, composite oxide hydrate, composite hydroxide, etc.), and more preferably a binary composite of bismuth and zirconium or a binary composite of magnesium and aluminum.
When the inorganic ion scavenger contains two or more types of metal atoms, the inorganic ion scavenger preferably contains two or more types (e.g., two to four types) of metal atoms whose content relative to all metal atoms in the inorganic ion scavenger is in the range of 1 to 99 mol %, and more preferably contains two or more types (e.g., two to four types) of metal atoms whose content relative to all metal atoms in the inorganic ion scavenger is in the range of 5 to 95 mol %.

The content of inorganic ion trapping agents is preferably 0.01 to 40% by mass, more preferably 0.1 to 20% by mass, and even more preferably 0.2 to 10% by mass, based on the total inorganic matter.

It is also preferable that the inorganic matter in the composition consists essentially of inorganic nitrides and inorganic ion adsorbents. For example, the total content of inorganic nitrides and inorganic ion adsorbents is more preferably 98 to 100% by mass, even more preferably 99.95 to 100% by mass, and particularly preferably 99.995 to 100% by mass, of the total inorganic matter.

It is also preferable that the inorganic substance (preferably an inorganic nitride or inorganic oxide, more preferably an inorganic nitride, and even more preferably boron nitride and/or aluminum nitride) contained in the composition is substantially composed of inorganic substances having an average particle size of 20 μm or more (preferably 30 μm or more). "Substantially comprising only inorganic substances having an average particle size of 20 μm or more" means that the content of inorganic substances having an average particle size of 20 μm or more exceeds 99 mass% of the total mass of the inorganic substances.

It is also preferable that the inorganic substances have different average particle sizes. For example, it is preferable to include both inorganic substance X, which is an inorganic substance having an average particle size of 20 μm or more, and inorganic substance Y, which is an inorganic substance having an average particle size of less than 20 μm.
The inorganic substance X preferably has an average particle size of 20 to 300 μm, more preferably 30 to 200 μm. The inorganic substance Y preferably has an average particle size of 1 nm or more but less than 20 μm, more preferably 10 nm or more and 15 μm or less.
The inorganic substance X is preferably an inorganic nitride or an inorganic oxide, more preferably an inorganic nitride, and even more preferably boron nitride. It is also preferable that the inorganic substance X is in an aggregated state.
The inorganic substance Y is preferably an inorganic nitride or an inorganic oxide, more preferably boron nitride or aluminum oxide. It is also preferable that the inorganic substance Y is in a form other than an aggregate.
The inorganic substance X and the inorganic substance Y may each be used alone or in combination of two or more.
The mass ratio of the content of inorganic substance X to the content of inorganic substance Y (content of inorganic substance X/content of inorganic substance Y) among the inorganic substances is preferably 50/50 to 99/1, more preferably 60/40 to 95/5, and even more preferably 60/40 to 90/10.

The inorganic substance (particularly boron nitride) may be surface-treated. Note that the surface treatment refers to a treatment different from the surface modification using a surface modifier, which will be described later.
By carrying out such treatment, functional groups are introduced onto the surface of the inorganic material, which makes it easier for the inorganic material to interact with phenolic compounds, epoxy compounds, and/or the surface modifiers described below, and it is believed that the thermal conductivity and peel strength of the formed thermal conductive material are further improved.
Examples of surface treatments include plasma treatments (vacuum plasma treatment, atmospheric pressure plasma treatment, aqua plasma treatment, etc.), ultraviolet irradiation treatment, corona treatment, electron beam irradiation treatment, ozone treatment, baking treatment, flame treatment, oxidizing agent treatment, etc. The oxidizing agent treatment may be carried out under acidic conditions or basic conditions (e.g., pH 12 or higher).

The content of inorganic substances in the composition is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, based on the total solid content of the composition. The upper limit is less than 100% by mass, preferably 95% by mass or less, and more preferably 83% by mass or less.

[Surface modifiers, surface-modified inorganic substances]
The composition of the present invention may further contain a surface modifier as a component different from the above-mentioned components.
The surface modifier is a component that modifies the surface of the inorganic substance.
As used herein, "surface modification" refers to a state in which an organic substance is adsorbed onto at least a portion of the surface of an inorganic substance. The form of adsorption is not particularly limited, as long as it is a bonded state. In other words, surface modification also includes a state in which an organic group obtained by partial detachment of the organic substance is bonded to the surface of the inorganic substance. The bond may be any bond, such as a covalent bond, a coordinate bond, an ionic bond, a hydrogen bond, a van der Waals bond, or a metallic bond. The surface modification may be performed so as to form a monolayer on at least a portion of the surface. A monolayer is a monolayer film formed by chemical adsorption of organic molecules and is known as a self-assembled monolayer (SAM). Note that, as used herein, the surface modification may be performed on only a portion or the entire surface of the inorganic substance.

As used herein, a "surface-modified inorganic material" refers to an inorganic material whose surface has been modified with a surface modifier. That is, a surface-modified inorganic material is a material comprising an inorganic material and a surface modifier adsorbed onto the surface of the inorganic material.
That is, in the composition of the present invention, the inorganic substance may constitute a surface-modified inorganic substance together with the surface modifier adsorbed onto the surface of the inorganic substance.
In the present invention, the composition may contain a surface-modified inorganic material, so that the composition contains an inorganic material and a surface modifier.
A part or all of the inorganic substance in the composition may constitute the surface-modified inorganic substance together with the surface modifier. For example, in the composition, some inorganic substances may constitute the surface-modified inorganic substance, while at the same time, inorganic substances may be present that are not involved in the formation of the surface-modified inorganic substance.
A part or all of the surface modifier in the composition may constitute the surface-modified inorganic substance together with the inorganic substance. For example, in the composition, a part of the surface modifier may constitute the surface-modified inorganic substance, and at the same time, a part of the surface modifier may be present that is not involved in the formation of the surface-modified inorganic substance.
In particular, the composition preferably contains a surface-modified inorganic nitride (preferably surface-modified boron nitride) in which the inorganic substance constituting the surface-modified inorganic substance is an inorganic nitride (preferably boron nitride, more preferably aggregated boron nitride having an average particle size of 20 μm or more). Part or all of the inorganic nitride (preferably boron nitride) in the composition may constitute the surface-modified inorganic nitride (preferably surface-modified boron nitride) together with a surface modifier.
The composition may also contain a surface-modified inorganic oxide (preferably surface-modified aluminum) in which the inorganic substance constituting the surface-modified inorganic substance is an inorganic oxide (preferably aluminum oxide). Part or all of the inorganic oxide (preferably aluminum oxide) in the composition may constitute the surface-modified inorganic oxide (preferably surface-modified aluminum oxide) together with the surface modifier.
The surface-modified inorganic material can be formed, for example, by contacting an inorganic material with a surface modifier. For example, the inorganic material, the surface modifier, and other components constituting the composition of the present invention may be mixed together to form the surface-modified inorganic material in the composition during the production process of the composition of the present invention.
Alternatively, for example, an inorganic substance and a surface modifier may be mixed in a solvent to prepare a mixed solution containing the surface-modified inorganic substance, and the surface-modified inorganic substance may be separated from the mixed solution by means of filtration or the like to obtain the separated surface-modified inorganic substance. The separated surface-modified inorganic substance may be used to prepare the composition of the present invention.

Conventional surface modifiers can be used, such as carboxylic acids such as long-chain alkyl fatty acids, organic phosphonic acids, organic phosphate esters, and organic silane molecules (silane coupling agents). Other surface modifiers that may be used include those described in, for example, JP 2009-502529 A, JP 2001-192500 A, and Japanese Patent No. 4694929.

The silane coupling agent is, for example, a compound having a hydrolyzable group directly bonded to a silicon atom.
Examples of the hydrolyzable group include an alkoxy group (preferably having 1 to 10 carbon atoms) and a halogen atom such as a chlorine atom.
The number of hydrolyzable groups directly bonded to Si atoms in the silane coupling agent is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no upper limit to the number, and it is, for example, 10,000 or less.
The silane coupling agent also preferably has a reactive group.
Specific examples of the reactive group include an epoxy group, an oxetanyl group, a vinyl group, a (meth)acrylic group, a styryl group, an amino group, an isocyanate group, a mercapto group, and an acid anhydride group.
The number of reactive groups in the silane coupling agent is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no upper limit to the number, and it is, for example, 10,000 or less.
Examples of silane coupling agents include 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptotriethoxysilane, and 3-ureidopropyltriethoxysilane.

When the composition of the present invention contains a surface modifier, a surface-modified inorganic substance may be prepared in advance and used as part of the raw materials of the composition. That is, the surface-modified inorganic substance prepared in advance may be mixed with other components of the composition, thereby introducing all or part of the surface modifier and inorganic substance into the composition in a form contained in the surface-modified inorganic substance prepared in advance.
Alternatively, a surface modifier and/or inorganic substance other than those contained in the surface-modified inorganic substance may be mixed with other components of the composition to introduce all or part of the surface modifier and/or inorganic substance into the composition. In this case, it is also preferable that the surface modifier is adsorbed onto the surface of the inorganic substance during the mixing process to form the surface-modified inorganic substance in the composition. In this case, a portion of the surface modifier may be present in the composition without contributing to the formation of the surface-modified inorganic substance.

The surface modifiers may be used alone or in combination of two or more.
When the composition contains a surface modifier, the content of the surface modifier is preferably from 0.005 to 5 mass %, more preferably from 0.05 to 3 mass %, based on the total solid content of the composition.
When the composition contains a surface modifier, the content of the surface modifier is preferably 0.01 to 10 mass %, more preferably 0.10 to 5 mass %, based on the total amount of inorganic substances.
The mass ratio of the surface modifier to the inorganic substance in the surface-modified inorganic substance (mass of the surface modifier adsorbed on the surface of the inorganic substance/mass of the inorganic substance) is preferably 0.00001 to 0.5, more preferably 0.0001 to 0.1.
When the composition contains a surface-modified inorganic material, the content of the surface-modified inorganic material is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 75% by mass or more, based on the total solid content of the composition. The upper limit is less than 100% by mass, preferably 95% by mass or less, and more preferably 83% by mass or less.
When the composition contains a surface-modified nitride (preferably surface-modified boron nitride), the content of the surface-modified nitride (preferably surface-modified boron nitride) is preferably 10 to 100 mass %, more preferably 40 to 100 mass %, and even more preferably 60 to 100 mass %, based on the total surface-modified inorganic materials.

[Curing accelerator]
The composition preferably further comprises a cure accelerator.
The curing accelerator preferably contains at least one selected from the group consisting of compounds represented by general formula (P1) and compounds represented by general formula (P2), and more preferably contains a compound represented by general formula (P3).
When the compound contained in the curing accelerator has optical isomers, any of the optical isomers may be used. Furthermore, one optical isomer may be used alone, or multiple optical isomers may be used in combination. When one optical isomer is primarily used, its optical purity (ee) is preferably 90 or more, more preferably 95 or more. Similarly, when optical isomers are present in the general formulae (P1) to (P3) shown below, any of the optical isomers may be included.

In formula (P1), ^Lp represents a single bond or a divalent linking group.
Examples of the divalent linking group include an ether group (-O-), a carbonyl group (-CO-), an ester group (-COO-), a thioether group (-S-), -SO ₂ -, -NR- (R is a hydrogen atom or an alkyl group), a divalent aliphatic hydrocarbon group (for example, an alkylene group, a cycloalkylene group, an alkenylene group (-CH=CH- etc.), an alkynylene group (-C≡C- etc.)), a divalent aromatic ring group (an arylene group and a heteroarylene group), and a group combining these. The divalent linking group may further have a substituent. Examples of the substituent include the substituents exemplified in the above substituent group Y.
The arylene group may be monocyclic or polycyclic, and preferably has 6 to 25 carbon atoms.
The arylene group is preferably a phenylene group, a naphthylene group, an anthracenylene group or a binaphthylene group, and more preferably a binaphthylene group.
^Lp is preferably a divalent aliphatic hydrocarbon group or a divalent aromatic ring group, more preferably an alkylene group or an arylene group.

R ^p11 to R ^p14 each independently represent a phenyl group which may have a substituent.
Examples of the substituent include the substituents exemplified in the above-mentioned group Y of substituents, and an alkyl group is preferable, and a linear or branched alkyl group having 1 to 3 carbon atoms is more preferable.

_np represents 0 or 1. _np is preferably 1.

In formula (P2), R ^p21 to R ^p24 each independently represent a phenyl group which may have a substituent.
Examples of the substituent include the substituents exemplified in the above-mentioned group Y of substituents, and an alkyl group is preferable, and a linear or branched alkyl group having 1 to 3 carbon atoms is more preferable.

X ⁻ represents an anion.
Examples of the anion include hydroxide ion, fluoride ion, chloride ion, bromide ion, iodide ion, hexafluorophosphate ion, tetrafluoroborate ion, tetraphenylborate ion, dicyanamide ion, alkylphosphate ion (e.g., diethylphosphate ion, etc.), hydrogen sulfate ion, dihydrogen phosphate ion, hydrogen phosphate ion, sulfamate ion, perchlorate ion, benzotriazolide anion, and tetratolylborate anion (e.g., tetra-p-tolylborate anion, etc.).
The anion is preferably a tetratolylborate anion.

In formula (P3), R ^p31 to R ^p34 each independently represent a phenyl group which may have a substituent.
Examples of the substituent include the substituents exemplified in the above-mentioned group Y of substituents, and an alkyl group is preferable, and a linear or branched alkyl group having 1 to 3 carbon atoms is more preferable.

Examples of curing accelerators include tris-orthotolylphosphine, triphenylphosphine, tris-para-tolylphosphine, tri-t-butylphosphine, tri-i-butylphosphine, tricyclohexylphosphine, tri-2-furylphosphine, dicyclohexylphenylphosphine, di-t-butylphenylphosphine, 1,2-bis(diphenylphosphino)ethane, cis-1,2-bis(diphenylphosphino)ethylene, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane, 4-(diphenylphosphino)styrene, 2-(diphenylphosphino)benzoic acid, 4-(diphenylphosphino)benzoic acid, 1,2-bis(diphenylphosphino)benzene, Bis[2-(diphenylphosphino)phenyl]ether, 1,1'-bis(diphenylphosphino)ferrocene (dppf), BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl), TolBINAP (2,2'-bis[(4-methylphenyl)phosphino]-1,1'-binaphthyl), XylBINAP (2,2'-bis[(3,5-dimethylphenyl) tBuBINAP (2,2'-bis(di-p-t-butylphenylphosphino)-1,1'-binaphthyl), 2,2'-bis[(4-t-butylphenyl)phosphino]-1,1'-binaphthyl, 2,2'-bis[(4-isopropylphenyl)phosphino]-1,1'-binaphthyl, 2,2'-bis[(naphthalen-1-yl)phosphino]-1,1'-binaphthyl, 2,2'-bis[(naphthalen-2-yl)phosphino]-1,1'-binaphthyl, 2,2'-bis[(naphthalen-2-yl)phosphino]-1,1'-binaphthyl, BICHEMP (2,2'-bis(dicyclohexylphosphino)-6,6'-dimethyl-1,1'-biphenyl), BPPFA (1-[1,2-bis-(diphenylphosphino)ferrocenyl]ethylamine), CHIRAPHOS (2,3-bis(diphenylphosphino)-1,1'-binaphthyl), ...), 2,2'-bis[(naphthalen-2-yl)phosphino]-1,1'-binaphthyl, BICHEMP (2,2'-bis(dicyclohexylphosphino)-6,6'-dimethyl-1,1'-biphenyl), BPPFA (1-[1,2-bis-(diphenylphosphino)ferrocenyl]ethylamine), CHIRAPHOS (2,3-bis(diphenylphosphino)-1,1'-binaphthyl), 2,2'-bis[(diphenylphosphino)-1,1'-binaphthyl] phosphino)butane), CYCPHOS (1-cyclohexyl-1,2-bis(diphenylphosphino)ethane), DEGPHOS (1-substituted-3,4-bis(diphenylphosphino)pyrrolidine), DIOP (2,3-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane), SKEWPHOS (2,4-bis(diphenylphosphino)penta and compounds containing a phosphorus atom such as 2,2'-bis(diphenylphosphino)-1,1'-bipyridines, SEGPHOS ((4,4'-bis-1,3-benzodioxole)-5,5'-diyl-bis(diphenylphosphino)), and BIFAP (2,2'-bis(diphenylphosphanyl)-1,1'-bisdibenzofuranyl).

Examples of curing accelerators include onium salt-based curing accelerators such as tetraphenylphosphonium tetraphenylborate (TPP-K), tetraphenylphosphonium tetra-p-tolylborate (TPP-MK), tetra-n-butylphosphonium laurate (TBP-LA), bis(tetra-n-butylphosphonium)pyromellitate, and quaternary phosphonium compounds (phosphonium salts) such as tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate adducts.

Further examples include boron trifluoride amine complexes and the compounds described in paragraph 0052 of JP-A-2012-067225.
Other examples include 2-methylimidazole (trade name: 2MZ), 2-undecylimidazole (trade name: C11-Z), 2-heptadecylimidazole (trade name: C17Z), 1,2-dimethylimidazole (trade name: 1.2DMZ), 2-ethyl-4-methylimidazole (trade name: 2E4MZ), 2-phenylimidazole (trade name: 2PZ), 2-phenyl-4-methylimidazole (trade name: 2P4MZ), 1-benzyl-2-methylimidazole (trade name: 1B2MZ), 1-benzyl-2-methylimidazole (trade name: 1B2MZ), 1-benzyl-4-methylimidazole (trade name: 1B4 ... 1-cyanoethyl-2-phenylimidazole (trade name: 1B2PZ), 1-cyanoethyl-2-methylimidazole (trade name: 2MZ-CN), 1-cyanoethyl-2-undecylimidazole (trade name: C11Z-CN), 1-cyanoethyl-2-phenylimidazolium trimellitate (trade name: 2PZCNS-PW), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2MZ-A), 2,4-diamino-6-[2'-undecylimidazolyl -(1')]-ethyl-s-triazine (trade name: C11Z-A), 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2E4MZ-A), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (trade name: 2MA-OK), 2-phenyl-4,5-dihydroxymethylimidazole (trade name: 2PHZ-PW), 2-phenyl-4-methyl-5- ... Examples of suitable curing accelerators include imidazole-based curing accelerators such as phenylimidazole (trade name: 2P4MHZ-PW), 1-cyanoethyl-2-phenylimidazole (trade name: 2PZ-CN), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2MZA-PW), and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (trade name: 2MAOK-PW) (all manufactured by Shikoku Chemical Industry Co., Ltd.). Furthermore, examples of suitable curing accelerators include the compounds described in paragraph 0052 of JP-A No. 2004-043405 as triarylphosphine-based curing accelerators. Examples of suitable curing accelerators include the compounds described in paragraph 0024 of JP-A No. 2014-005382 as phosphorus-based curing accelerators in which triphenylborane is added to triarylphosphine.

The molecular weight of the curing accelerator is often 200 or more, preferably 250 or more, more preferably 400 or more, even more preferably 430 or more, and particularly preferably 600 or more. The upper limit is preferably 10,000 or less, more preferably 1,000 or less, and even more preferably 800 or less.
When the molecular weight of the curing accelerator is 250 or more, the vaporization of the curing accelerator itself and/or its thermal decomposition products can be more effectively suppressed when subjected to high-temperature heat treatment (for example, the evaluation of solder heat resistance II in the Examples section), resulting in better solder heat resistance. Also, when the molecular weight of the curing accelerator is 10,000 or less, it is easy to function as a curing accelerator.

Among these, the curing accelerator preferably contains a compound containing a phosphorus atom, and also preferably contains a phosphonium salt, in order to obtain better effects of the present invention. The curing accelerator may be a compound containing a phosphorus atom or a phosphonium salt itself. When a phosphonium salt is used as the curing accelerator, the storage stability of the semi-cured film formed from the composition is also improved.
The content of the phosphorus atom-containing compound or phosphonium salt is preferably from 10 to 100 mass %, more preferably from 50 to 100 mass %, and even more preferably from 80 to 100 mass %, based on the total mass of the curing accelerator.

The curing accelerators may be used alone or in combination of two or more.
The content of the curing accelerator is preferably 0.002% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.07% by mass or more, based on the total solid content of the composition, and is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, based on the total solid content of the composition.
The content of the curing accelerator is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.55% by mass or more, based on the total amount of epoxy compounds. The content of the curing accelerator is preferably 40% by mass or less, more preferably 12% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on the total amount of epoxy compounds.

[Ion Scavenger]
The compositions of the present invention may also contain an ion scavenger.
The ion scavenger adsorbs ionic impurities in the composition or in a thermally conductive material formed using the composition, thereby enabling the insulating properties of the thermally conductive material to be better maintained even when the composition or the thermally conductive material absorbs moisture.
Examples of the ion trapping agent include the inorganic ion trapping agents and organic ion trapping agents described above.
Examples of organic ion scavengers include triazine thiol compounds, triazine amine compounds, benzimidazole compounds, benzotriazole compounds, aminotriazole compounds, and bisphenol reducing agents.
All or part of the inorganic substances described above may also function as ion scavengers.

An example of the triazine thiol compound is 2-dibutylamino-4,6-dimercapto-s-triazine.
The benzimidazole compound includes, for example, benzimidazole.
Examples of benzotriazole compounds include 1H-benzotriazole, carboxybenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol].
Examples of aminotriazole compounds include 3-amino-1,2,4-triazole and 3,5-diamino-1,2,4-triazole.
Examples of bisphenol reducing agents include 2,2'-methylenebis-(4-ethyl-6-t-butylphenol) and 4,4'-butylidenebis-(6-t-butyl-3-methylphenol).

Commercially available ion scavengers may be used, such as DHF-4A, DHT-4A, DHT-4A-2, DHT-4C, Kyoward 500, KW-2000, and KW-2100 (trade names, manufactured by Kyowa Chemical Industry Co., Ltd.); IXE-100, IXE-500, IXE-600, IXE-700F, IXE-800, IXE-6107, IXEPLAS-A1, IXEPLAS-A2, and IXEPLAS-B1 (trade names, manufactured by Toagosei Co., Ltd.); Jisnet DB (trade name, manufactured by Sankyo Pharmaceutical Co., Ltd.); VD-3 and VD-5 (trade names, manufactured by Shikoku Kasei Co., Ltd.); and Yoshinox BB (trade name, manufactured by Yoshitomi Pharmaceutical Co., Ltd.).

When the composition contains an ion scavenger, the content of the ion scavenger (an inorganic ion scavenger and/or an organic ion scavenger) is preferably 0.01 to 10 mass%, more preferably 0.1 to 20 mass%, and still more preferably 0.2 to 10 mass%, based on the total solid content of the composition.
When the ion scavenger contains an inorganic ion scavenger, part or all of the ion scavenger may simultaneously fall under the category of inorganic substances.
The ion trapping agents may be used alone or in combination of two or more.

〔solvent〕
The composition may further comprise a solvent.
The type of solvent is not particularly limited, but is preferably an organic solvent, such as cyclopentanone, cyclohexanone, ethyl acetate, methyl ethyl ketone, dichloromethane, and tetrahydrofuran.
When the composition contains a solvent, the content of the solvent is preferably an amount that makes the solids concentration of the composition 20 to 90 mass %, more preferably an amount that makes the solids concentration of the composition 30 to 85 mass %, and even more preferably an amount that makes the solids concentration of the composition 50 to 80 mass %.
The content of the solvent is preferably from 10 to 80% by mass, more preferably from 15 to 70% by mass, and even more preferably from 20 to 50% by mass, based on the total mass of the composition.

[Method for producing the composition]
The method for producing the composition is not particularly limited, and any known method can be used, for example, by mixing the various components described above. When mixing, the various components may be mixed all at once or sequentially.
The method for mixing the components is not particularly limited, and known methods can be used. The mixing device used for mixing is preferably a submerged disperser, and examples include agitators such as a planetary centrifugal mixer and a high-speed rotary shear type agitator, a colloid mill, a roll mill, a high-pressure injection type disperser, an ultrasonic disperser, a bead mill, and a homogenizer. One type of mixing device may be used alone, or two or more types may be used. Degassing treatment may be performed before, after, and/or simultaneously with mixing.

[Method of curing the composition]
The composition of the present invention is preferably a composition for forming a thermally conductive material.
The composition of the present invention is cured to obtain a thermally conductive material.
The method for curing the composition is not particularly limited, but a thermal curing reaction is preferred.
The heating temperature during the thermosetting reaction is not particularly limited and may be appropriately selected, for example, within the range of 50 to 250° C. Furthermore, when carrying out the thermosetting reaction, heat treatments at different temperatures may be carried out multiple times.
The curing treatment is preferably carried out on a composition in the form of a film or sheet. Specifically, for example, the composition may be applied to form a film and then subjected to a curing reaction.
When performing the curing treatment, it is preferable to apply the composition to a substrate to form a coating film and then cure it. In this case, the coating film formed on the substrate may be brought into contact with another substrate and then cured. The cured product (thermal conductive material) obtained after curing may or may not be separated from one or both of the substrates.
Alternatively, when carrying out the curing treatment, the composition may be applied to separate substrates to form coating films on each substrate, and the curing treatment may be carried out in a state where the resulting coating films are in contact with each other. The cured product (thermal conductive material) obtained after curing may or may not be separated from one or both of the substrates.

The curing treatment may be completed when the composition is in a semi-cured state, or after the composition is in a semi-cured state, further curing treatment may be carried out to complete the curing.
The curing treatment for bringing the composition into a semi-cured state (also referred to as "semi-curing treatment") and the curing treatment for complete curing (also referred to as "main curing treatment") may be carried out in separate steps.

For example, in the semi-curing treatment, after applying a composition to a substrate to form a coating film, the coating film on the substrate may be heated without pressure to form a semi-cured thermal conductive material (also referred to as a "semi-cured film" or "semi-cured sheet"). Alternatively, the coating film on the substrate may be heated while also being pressed to form a semi-cured film. When press processing is performed, the press processing may be performed before, after, or during the heating process. Press processing in the semi-curing treatment may facilitate adjustment of the film thickness of the resulting semi-cured film and/or reduction of the amount of voids in the semi-cured film.
The semi-curing treatment may be carried out in a state where coating films formed on different substrates are laminated together, or may be carried out without laminating the coating films together. The semi-curing treatment may also be carried out in a state where the coating film formed from the composition is in contact with a material other than the coating film.

The resulting semi-cured film may be used as a heat conductive material as is, or may be further subjected to a main curing treatment and then used as a completely cured heat conductive material.
In the main curing treatment, the semi-cured film may be heated as is without pressure, or may be heated after or while being pressed. In this case, the main curing treatment may be performed in a state where separate semi-cured films are stacked on top of each other, or may be performed without stacking the semi-cured films on top of each other.
The main curing treatment may be carried out in a state where the semi-cured film is placed in contact with a device or the like in which it is used. It is also preferable that the main curing treatment adheres the device to the thermally conductive material of the present invention.

There are no limitations on the press used for press working that may be carried out during the hardening treatment in the semi-hardening treatment and/or the full hardening treatment, and for example, a flat press or a roll press may be used.
When using a roll press, for example, it is preferable to sandwich the coated substrate obtained by forming a coating film on the substrate between a pair of opposing rolls, and apply pressure in the film thickness direction of the coated substrate while rotating the pair of rolls to pass the coated substrate. The coated substrate may have a substrate on only one side of the coating film, or may have a substrate on both sides of the coating film. The coated substrate may be passed through the roll press once or multiple times.
During the hardening treatment in the semi-hardening treatment and/or the full hardening treatment, either one of the treatment by plate pressing and the treatment by roll pressing may be carried out, or both may be carried out.

For information on the production of thermally conductive materials, including curing reactions, please also refer to "High Thermally Conductive Composite Materials" (CMC Publishing, written by Takezawa Yoshitaka).

The shape of the thermally conductive material is not particularly limited, and it can be molded into various shapes depending on the application. A typical shape of the molded thermally conductive material is, for example, a sheet shape.
That is, the thermally conductive material obtained using the composition of the present invention is preferably a thermally conductive sheet.
Furthermore, the thermal conductivity of the thermally conductive material obtained using the composition of the present invention is preferably isotropic rather than anisotropic.

It is also preferable that the heat conductive material (preferably a heat conductive sheet) has reduced moisture absorption.
Specifically, the thermally conductive material (preferably the thermally conductive sheet) preferably has a mass change rate calculated by the following formula of less than 1.0%, more preferably less than 0.7%, and even more preferably less than 0.5%. The lower limit of the mass change rate is usually 0% by mass or more.
W1: Mass of a dry thermal conductive material (preferably a thermal conductive sheet) after drying for 2 hours in an environment at 120°C. W2: Mass of a hygroscopic thermal conductive material (preferably a thermal conductive sheet) after leaving the dry thermal conductive material (preferably a thermal conductive sheet) in an environment at 85°C and 85% RH for 24 hours. Note that drying in an environment at 120°C when determining W1 should be carried out in a sufficiently dehumidified environment.

The thermally conductive material is preferably insulating (electrically insulating), in other words, the composition of the present invention is preferably a thermally conductive insulating composition.
For example, the volume resistivity of the thermal conductive material at 23°C and a relative humidity of 65% is preferably ¹⁰ Ω·cm or more, more preferably ¹⁰ Ω·cm or more, and even more preferably 10 ^Ω ·cm or more. There is no particular upper limit, but it is usually 10 ^Ω ·cm or less.

[Uses of thermal conductive materials]
The thermally conductive material obtained using the composition of the present invention can be used as a heat dissipation material such as a heat dissipation sheet, and can be used for heat dissipation applications in various devices. More specifically, a device with a thermally conductive layer can be produced by disposing a thermally conductive layer containing the thermally conductive material of the present invention on the device, and the heat generated from the device can be efficiently dissipated by the thermally conductive layer. The thermally conductive layer may be a thermally conductive layer containing a thermally conductive multilayer sheet, as described below.
The thermally conductive material obtained using the composition of the present invention has sufficient thermal conductivity and high heat resistance, and is therefore suitable for heat dissipation applications in power semiconductor devices used in various electrical equipment such as personal computers, general home appliances, and automobiles.
Furthermore, since the thermally conductive material obtained using the composition of the present invention has sufficient thermal conductivity even in a semi-cured state, it can be used as a heat dissipation material to be placed in areas where it is difficult for light for photocuring to reach, such as gaps between components of various devices.In addition, since it has excellent adhesive properties, it can also be used as a thermally conductive adhesive.

The thermally conductive material obtained using the composition of the present invention may be used in combination with other components other than the component formed from the present composition.
For example, a thermally conductive material (such as a thermally conductive sheet) may be combined with a support (adherend) other than the layer formed from the present composition.
Examples of the support (adherend) include plastic materials, metal materials, and glass. Examples of the plastic materials include polyesters such as polyethylene terephthalate (PET), polycarbonates, acrylic resins, epoxy resins, polyurethanes, polyamides, polyolefins, cellulose derivatives, and silicones. Examples of the metal materials include copper and aluminum.
The support (adherend) is also preferably in the form of a sheet.
The thickness of the sheet-like thermally conductive material (thermally conductive sheet) is preferably 100 to 300 μm, more preferably 150 to 250 μm.

Furthermore, the thermally conductive material (preferably the thermally conductive sheet) may be combined with an adhesive layer and/or a pressure-sensitive adhesive layer.
By joining the thermally conductive material to an object to which heat should be transferred, such as a device, via such an adhesive layer and/or pressure-sensitive adhesive layer, a stronger bond between the thermally conductive material and the object can be achieved. The thermally conductive material formed from the composition of the present invention also has good adhesion to the adhesive layer and pressure-sensitive adhesive layer, and peeling at the interface between the thermally conductive material and the adhesive layer or pressure-sensitive adhesive layer can be suppressed.
For example, a thermally conductive multilayer sheet may be produced which has a thermally conductive sheet and an adhesive layer or pressure-sensitive adhesive layer provided on one or both sides of the thermally conductive sheet.
One or both sides of the thermally conductive sheet may be provided with either an adhesive layer or a pressure-sensitive adhesive layer, or both. An adhesive layer may be provided on one side of the thermally conductive sheet, and a pressure-sensitive adhesive layer may be provided on the other side. Furthermore, an adhesive layer and/or a pressure-sensitive adhesive layer may be provided partially or entirely on one or both sides of the thermally conductive sheet.
As described above, in the present invention, the thermally conductive material such as the thermally conductive sheet may be in a semi-cured state (semi-cured film), and the thermally conductive sheet in the thermally conductive multilayer sheet may be in a semi-cured state. The adhesive layer in the thermally conductive multilayer sheet may be in a cured, semi-cured, or uncured state.

The present invention will be described in more detail below based on the following examples. The materials, amounts used, ratios, processing details, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

<<Test X>>
First, Test X (Examples 1 to 75, Comparative Examples 1 and 2) was carried out under the conditions and procedures shown below.

[Preparation and Evaluation of Compositions]
[Various ingredients]
The various components used in the examples and comparative examples are listed below.
The components to be used in Test Y, which will be described later, are also shown below.

<Phenol compounds>
The phenol compounds used in the examples and comparative examples are shown below.

A-3: MEH-7500 (manufactured by Meiwa Kasei, a phenolic compound without a triazine skeleton)

<Epoxy Compound>
The epoxy compounds used in the examples and comparative examples are shown below.
The weight average molecular weight of B-8 is 3,000, and the average value of n of B-9 is 10.

<Maleimide Compound>
The maleimide compounds used in the examples and comparative examples are shown below.

<Cyanate Compounds>
The cyanate compounds used in the examples and comparative examples are shown below.
G-1: TA (2,2'-di(4-cyanatophenyl)propane, manufactured by Mitsubishi Gas Chemical Company, Inc.)
G-2: TA-100 (manufactured by Mitsubishi Gas Chemical Company, Inc., a prepolymer of 2,2'-di(4-cyanatophenyl)propane)
G-3: AROCY XU371 (manufactured by HUNSMAN, phenol novolac cyanate)
G-4: P-201 (manufactured by Mitsubishi Gas Chemical Company, Inc.)

<Inorganic nitrides, inorganic oxides, or surface-modified inorganic ... nitrides, inorganic oxides, inorganic nitrides, inorganic nitrides, inorganic nitrides, inorganic nitride
The inorganic nitrides, inorganic oxides, or surface-modified products thereof (surface-modified inorganic nitrides or surface-modified inorganic oxides) used in the Examples and Comparative Examples are shown below. Note that in all of the surface-modified products (surface-modified inorganic nitrides or surface-modified inorganic oxides), the content of the surface modifier relative to the total mass of the surface-modified product was more than 0 mass% and less than 1 mass%.
HP-40: Agglomerated boron nitride, average particle size: 40 μm, manufactured by Mizushima Ferroalloy Co., Ltd. AA-3: Aluminum oxide, average particle size: 3 μm, manufactured by Sumitomo Chemical Co., Ltd. PTX-60: Agglomerated boron nitride, average particle size: 60 μm, manufactured by Momentive Corporation SP-3: Scaly boron nitride, average particle size: 4 μm, manufactured by Denka Company Limited BN1: Surface-modified boron nitride manufactured by Manufacturing Method 1 shown below BN2: Surface-modified boron nitride manufactured by Manufacturing Method 2 shown below BN3: Surface-modified boron nitride manufactured by Manufacturing Method 3 shown below Boron BN4: Surface-modified boron nitride produced by Production Method 4 described below BN5: Surface-modified boron nitride produced by Production Method 5 described below BN6: Surface-modified boron nitride produced by Production Method 6 described below BN7: Surface-modified boron nitride produced by Production Method 7 described below BN8: Surface-modified boron nitride produced by Production Method 8 described below BN9: Surface-modified boron nitride produced by Production Method 9 described below BN10: Surface-modified boron nitride produced by Production Method 10 described below

(Production Method 1 (Production of BN1))
Boron nitride (PTX-60 described above) (50 g) was added to aqueous NaOH (40 g NaOH/400 ml water) and stirred. Sodium persulfate solution (9.6 g sodium persulfate/100 ml water) was then added to the aqueous NaOH, and the temperature of the NaOH solution was raised to 50°C and the mixture was stirred for an additional 3 hours (modification step). A Three-One Motor manufactured by Shinto Scientific Co., Ltd. was used for stirring at 150 rpm.
After the NaOH water was cooled to room temperature, the boron nitride in the NaOH water was filtered off, and the filtered boron nitride was washed with water (500 ml) and acetonitrile (250 ml) to obtain modified boron nitride 1.
The obtained modified boron nitride 1 was stirred in acetonitrile (100 ml), and a hydrolysis adjusted solution (1.25 g) of a silane coupling agent (X12-984S, manufactured by Shin-Etsu Chemical Co., Ltd.) was further added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment (adsorption step).
The modified boron nitride 1 in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 1 (also referred to as "BN1").
The hydrolysis-adjusted solution of the silane coupling agent was prepared by mixing 1 g of the silane coupling agent with 500 μl of ethanol, 500 μl of 2-propanol, 720 μl of water, and 100 μl of acetic acid, followed by stirring for 1 hour. In the subsequent manufacturing methods, the formulation of the hydrolysis-adjusted solution of the silane coupling agent is the same unless otherwise specified.
Furthermore, "X12-984S" is a polymer-type silane coupling agent having an epoxy group and an ethoxysilyl group.
In Production Method 1, the pH of the liquid (aqueous solution) obtained by mixing NaOH water (NaOH: 40 g/water: 400 ml), boron nitride 50 g, and sodium persulfate water (sodium persulfate: 9.6 g/water: 100 ml) was 14.

(Manufacturing Method 2 (Manufacturing of BN2))
Boron nitride (PTX-60 mentioned above) (50 g) was added to water (400 ml) and stirred to obtain a mixed solution. 30 mass % hydrogen peroxide solution (30 ml) was further added to the mixed solution, and then the mixed solution was heated to 50°C and stirred for an additional 3 hours. A Three-One Motor manufactured by Shinto Scientific Co., Ltd. was used for stirring at 150 rpm.
After the mixture was cooled to room temperature, the boron nitride in the mixture was filtered off and washed with water (500 ml) and acetonitrile (250 ml) to obtain modified boron nitride.
The resulting modified boron nitride was stirred in acetonitrile (100 ml), and 1.25 g of a hydrolysis-adjusted solution of a silane coupling agent (KBM-403) was added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment.
The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 2 (also referred to as "BN2").
"KBM-403" is 3-glycidoxypropyltrimethoxysilane.
In Production Method 2, the pH of the liquid (aqueous solution) obtained by mixing water (400 ml), 50 g of boron nitride, and 30 mass % hydrogen peroxide solution (30 ml) was 5.

(Production Method 3 (Production of BN3))
Surface-modified boron nitride 3 (also referred to as "BN3") was obtained in the same manner as Production Method 1, except that the NaOH water used in Production Method 1 was changed to (NaOH: 0.02 g/water: 400 ml).
In Production Method 3, the pH of the liquid (aqueous solution) obtained by mixing NaOH water (NaOH: 0.02 g/water: 400 ml), boron nitride 50 g, and sodium persulfate water (sodium persulfate: 9.6 g/water: 100 ml) was 11.

(Manufacturing Method 4 (Manufacturing of BN4))
Boron nitride (PTX-60 described above) (50 g) was heated at 1000° C. for 1 hour in an oxidizing atmosphere to obtain modified boron nitride.
The resulting modified boron nitride was stirred in acetonitrile (100 ml), and 1.25 g of a hydrolysis-adjusted solution of a silane coupling agent (KBM-403) was added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment.
The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 4 (also referred to as "BN4").

(Manufacturing Method 5 (Manufacturing of BN5))
Boron nitride (PTX-60 described above) (50 g) was stirred in acetonitrile (100 ml), and a hydrolysis adjusted solution of a silane coupling agent (KBM-403) (1.25 g) was further added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment.
The boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 5 (also referred to as "BN5").

(Production Method 6 (Production of BN6))
Boron nitride (HP-40 mentioned above) (15 g) was subjected to vacuum plasma treatment (gas type: O ₂ , pressure: 30 Pa, output: 500 W) using a Plasma Cleaner PDC210 (manufactured by Yamato Scientific Co., Ltd.) The boron nitride to be treated was stirred every 5 minutes of vacuum plasma treatment, and the vacuum plasma treatment was continued until the total treatment time reached 30 minutes, yielding modified boron nitride particles.
The obtained modified boron nitride was stirred in acetonitrile (30 ml), and a hydrolysis adjusted solution (0.42 g) of a silane coupling agent (X12-984S, manufactured by Shin-Etsu Chemical Co., Ltd.) was further added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment.
The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (30 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 6 (also referred to as "BN6").
Furthermore, "X12-984S" is a polymer-type silane coupling agent having an epoxy group and an ethoxysilyl group.

(Production Method 7 (Production of BN7))
Boron nitride (50 g of the above-mentioned HP-40) was added to an aqueous NaOH solution (40 g NaOH/400 ml water) and stirred. After adding aqueous sodium persulfate (9.6 g sodium persulfate/100 ml water) to the NaOH solution, the temperature of the NaOH solution was raised to 50°C and the solution was stirred for an additional 3 hours. A Three-One Motor (manufactured by Shinto Scientific Co., Ltd.) was used for stirring at a rotation speed of 150 rpm. After cooling the NaOH solution to room temperature, the boron nitride in the NaOH solution was filtered and washed with water (500 ml) and acetonitrile (250 ml) to obtain modified boron nitride.
The obtained modified boron nitride was stirred in acetonitrile (100 ml), and a hydrolysis adjusted solution (1.25 g) of a silane coupling agent (X12-984S manufactured by Shin-Etsu Chemical Co., Ltd.) was further added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment. The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 7 (also referred to as "BN7").

(Manufacturing Method 8 (Manufacturing of BN8))
Boron nitride (HP-40 as described above, 50 g) was added to water (400 ml) and stirred to obtain a mixed solution. Sodium hypochlorite water (sodium hypochlorite pentahydrate: 48 g/water: 100 ml) was further added to the mixed solution, and the mixed solution was then heated to 50°C and stirred for an additional 3 hours. A Three-One Motor manufactured by Shinto Scientific Co., Ltd. was used for stirring at 150 rpm.
After the mixture was cooled to room temperature, the boron nitride in the mixture was filtered off and washed with water (500 ml) and acetonitrile (250 ml) to obtain modified boron nitride.
The obtained modified boron nitride was stirred in acetonitrile (100 ml), and a hydrolysis adjusted solution (1.25 g) of a silane coupling agent (X12-984S manufactured by Shin-Etsu Chemical Co., Ltd.) was further added to the acetonitrile. The acetonitrile was stirred at room temperature for 3 hours to carry out an adsorption treatment. The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 8 (also referred to as "BN8").

(Production Method 9 (Production of BN9))
Boron nitride (50 g of the above-mentioned HP-40) was heated at 1000°C for 1 hour to obtain modified boron nitride. The obtained modified boron nitride was reslurried and washed with water (500 ml), filtered, and then stirred in acetonitrile (100 ml). To the acetonitrile, 1.25 g of a hydrolysis-adjusted solution of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added. The acetonitrile was stirred at room temperature for 3 hours to perform an adsorption treatment. The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 9 (also referred to as "BN9").
"KBM-403" is 3-glycidoxypropyltrimethoxysilane.

(Manufacturing Method 10 (Manufacturing of BN10))
Boron nitride (50 g of the above-mentioned HP-40) was heated at 900°C for 4 hours to obtain modified boron nitride. The obtained modified boron nitride was reslurried and washed with water (500 ml), filtered, and then stirred in acetonitrile (100 ml). To the acetonitrile, 1.25 g of a hydrolysis-adjusted solution of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added. The acetonitrile was stirred at room temperature for 3 hours to perform an adsorption treatment. The modified boron nitride in the acetonitrile was filtered, washed with acetonitrile (100 ml), and dried in an oven at 40°C to obtain surface-modified boron nitride 10 (also referred to as "BN10").

<Curing accelerator>
The curing accelerators used in the examples and comparative examples are shown below.
The value in parentheses after each compound name indicates the molecular weight of each compound.
C-1: Tris(orthotolyl)phosphine (304.37)
C-2: triphenylphosphine (262.29)
C-3: 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole) (204.23)
C-4: TPP-MK (tetraphenylphosphonium tetra-p-tolylborate) (658.62)
C-5: (S)-(-)-BINAP ((S)-(-)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) (622.69)
C-6: (S)-(-)-TolBINAP ((S)-(-)-2,2'-bis(di-p-tolylphosphino)-1,1'-binaphthyl) (678.80)
C-7: (S)-(-)-XylBINAP ((S)-(-)-2,2'-bis[di(3,5-xylyl)phosphino]-1,1'-binaphthyl) (734.90)
C-8: (R)-(+)-BINAP ((R)-(+)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) (622.69)
C-9: (R)-(+)-TolBINAP ((R)-(+)-2,2'-bis(di-p-tolylphosphino)-1,1'-binaphthyl) (678.80)
C-10: (R)-(+)-XylBINAP ((R)-(+)-2,2'-bis[di(3,5-xylyl)phosphino]-1,1'-binaphthyl) (734.90)
C-11: (±)-BINAP ((±)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) (622.69)

<Ion scavenger>
The ion scavengers used in the examples and comparative examples are shown below.
F-1: KW-2000, _aluminum oxide/ _magnesium oxide solid solution ( _{Mg0.7Al0.3O1.15} ), manufactured by Kyowa Chemical Industry Co., Ltd. F-2: KW-2100, aluminum oxide/magnesium oxide solid solution, manufactured by Kyowa Chemical Industry Co., Ltd. F-3: KW-2200, aluminum oxide/magnesium oxide solid solution, manufactured by Kyowa Chemical Industry Co., Ltd. F-4: IXE-600, Bi, Sb-based, manufactured by Toagosei Co., Ltd. F-5: IXE-700F, Mg, Al-based, manufactured by Toagosei Co., Ltd. F-6: IXE-6107, Zr, Bi-based, manufactured by Toagosei Co., Ltd.

<Solvent>
Cyclopentanone was used as the solvent.

[Preparation of Composition]
The solvent, phenolic compound, epoxy compound (optional), ion scavenger (optional), specific compound (maleimide compound and/or cyanate compound), and curing accelerator were mixed in this order, and then the inorganic substance or surface-modified inorganic substance was added. The resulting mixture was treated for 5 minutes in a planetary centrifugal mixer (THINKY Corporation, Awatori Rentaro ARE-310) to obtain a composition (curable composition) of each Example or Comparative Example.

The amount of solvent added was such that the solid content of the composition was 50 to 80% by mass.
The solid content of each composition was adjusted within the above range so that the viscosity of each composition was approximately the same.
When the composition contains both a phenolic compound and an epoxy compound, the total content of the epoxy compound and the phenolic compound relative to the total solid content of the composition was the amount shown in the "Total amount (mass%)" column in Table 1, and the amounts of the epoxy compound and the phenolic compound added were adjusted so that they were equivalent (amounts such that the number of epoxy groups in the epoxy compound was equal to the number of hydroxyl groups in the phenolic compound).
When the composition contained only one of a phenol compound and an epoxy compound, the amount of the one component added was adjusted so that the content of the one component relative to the total solid content of the composition was the amount shown in the "Total amount (mass%)" column in Table 1.
In the composition, the amounts of the curing accelerator, inorganic substance (inorganic nitride, inorganic oxide, or surface-modified product thereof), ion scavenger, maleimide compound, and cyanate compound were each adjusted to the amounts (% by mass) shown in parentheses in each box in Table 1, relative to the total solid content of the composition.

[evaluation]
[Preparation of semi-cured sheet (semi-cured film)]
Using an applicator with a micrometer, the prepared composition was uniformly applied onto the release surface of a release-treated PET film (PET756501 manufactured by Lintec Corporation, film thickness 75 μm), and then dried at 120°C for 4 minutes to produce a semi-cured sheet (semi-cured film).

[Preparation of thermally conductive sheet]
The surface of the obtained semi-cured sheet opposite the PET film was covered with a release-treated PET film and heat-pressed in air (heat plate temperature 180 ° C, pressure 20 MPa for 5 minutes). This was then heat-treated at 180 ° C for 90 minutes under normal pressure to obtain a resin sheet. The PET films on both sides of the resin sheet were peeled off to obtain a thermally conductive sheet (thermal conductive material) with an average thickness of 120 μm.

[Method for evaluating thermal conductivity]
(1) The thermal diffusivity of the thermal conductive sheet in the thickness direction was measured by the laser flash method using "LFA467" manufactured by NETZSCH.
(2) Using a balance "XS204" manufactured by Mettler Toledo, the specific gravity of the thermally conductive sheet was measured by the Archimedes method (using a "solid specific gravity measurement kit").
(3) Using a DSC320/6200 manufactured by Seiko Instruments Inc., the specific heat of the thermally conductive sheet at 25° C. was determined under the condition of a temperature increase of 10° C./min.
(4) The thermal conductivity of the thermally conductive sheet was calculated by multiplying the obtained thermal diffusivity by the specific gravity and specific heat.

The thermal conductivity of the thermally conductive sheet was classified according to the following criteria, and the thermal conductivity of the thermally conductive sheet (thermally conductive material) obtained using the composition of each Example or Comparative Example was evaluated.
A+: 17 W/mK or more A: 15 W/mK or more but less than 17 W/mK B: 13 W/mK or more but less than 15 W/mK C: 10 W/mK or more but less than 13 W/mK D: Less than 10 W/mK

[Evaluation of Tg (heat resistance)]
The Tg of the obtained thermally conductive sheet was measured.
The measurement was performed using a dynamic viscoelasticity measuring device "Rheogel-E4000" manufactured by UBM, and the tan δ peak at a frequency of 1 Hz was taken as Tg. The temperature was increased at a rate of 5°C/min in the range of 25 to 300°C.

The Tg of the thermally conductive sheet was classified according to the following criteria, and the heat resistance of the thermally conductive sheet (thermally conductive material) obtained using the composition of each Example or Comparative Example was evaluated.
A+: 180°C or higher A: 170°C or higher but less than 180°C B: 160°C or higher but less than 170°C C: 150°C or higher but less than 160°C D: Less than 150°C

[Evaluation of insulation properties]
A voltage of 1 kV was applied to a sample (a thermally conductive sheet having a thickness of 120 μm, prepared by the above method) in an environment of 85° C. and 85% RH, and the time until the sample experienced dielectric breakdown was measured.
The time until the sample experienced dielectric breakdown was classified according to the following criteria and used to evaluate the insulating properties of the thermally conductive sheets (thermally conductive materials) obtained using the compositions of each Example or Comparative Example.
A: 500 hours or more B: 100 hours or more but less than 500 hours C: 50 hours or more but less than 100 hours D: Less than 50 hours

[Evaluation of moisture absorption]
The moisture absorption of the obtained thermally conductive sheet was evaluated.
The thermally conductive sheet was dried at 120°C for 2 hours using a sufficiently dehumidified dryer to obtain a dry thermally conductive sheet. The dry thermally conductive sheet was then placed in an environment of 85°C and 85% RH for 24 hours to obtain a hygroscopic thermally conductive sheet.
The mass change rate of these thermally conductive sheets was calculated according to the following formula, and the moisture absorption of the thermally conductive sheets was evaluated according to the following classification. The smaller the mass change rate, the more suppressed the moisture absorption, which is preferable.
Mass change rate (%) = (W2 - W1) / W1 x 100
W1: Mass of the dry thermal conductive sheet after drying for 2 hours in an environment at 120°C. W2: Mass of the moisture-absorbed thermal conductive sheet after leaving the dry thermal conductive sheet in an environment at 85°C and 85% RH for 24 hours. A: Mass change rate is less than 0.5%. B: Mass change rate is 0.5% or more but less than 0.7%. C: Mass change rate is 0.7% or more but less than 1.0%. D: Mass change rate is 1.0% or more.

[Evaluation of solder heat resistance]
After peeling the PET film from the obtained semi-cured sheet, the sheet was sandwiched between a copper substrate having a thickness of 2 mm and copper foil having a thickness of 0.15 mm, and then hot-pressed in air (heat plate temperature: 180°C, pressure: 20 MPa, treatment for 5 minutes) to obtain a laminate having a "copper substrate-thermal conductive sheet-copper foil" configuration.
The 0.15 mm copper foil in the laminate was etched into a circular shape with a diameter of 2 cm, and the laminate was used as a sample for solder heat resistance test having a configuration of "copper substrate - thermally conductive sheet - circular copper foil with a diameter of 2 cm".
The sample was subjected to a heat treatment at least once, in which the sample was heated at 300° C. for 3 minutes and then cooled to room temperature (25° C.). After that, a circular copper foil having a diameter of 2 cm was peeled off from the sample that had been subjected to the heat treatment at least once.
The state of failure of the peeled samples was visually observed, and if cohesive failure of the thermally conductive sheet occurred over the entire peeled surface, the sample was deemed to have passed. If interfacial peeling occurred over part or the entire surface between the copper substrate and the thermally conductive sheet and/or between the thermally conductive sheet and the 2 cm diameter circular copper foil, the sample was deemed to have failed.
Based on the relationship between the number of heat treatments and whether the sheet was passed or failed, the solder heat resistance of the thermal conductive sheet was evaluated according to the following classification.
A: Passed the heat treatment three times. B: Passed the heat treatment twice, but failed after three times. C: Passed the heat treatment once, but failed after two times. D: Failed after one heat treatment.

[Evaluation of Solder Heat Resistance II]
Solder heat resistance II was evaluated in the same manner as in the above [Evaluation of solder heat resistance], except that the heating temperature was changed from 300°C to 320°C.

[result]
Table 1 is shown below.
Table 1 shows the solid content of the composition and the test results for each example or comparative example.

The results shown in the table confirm that the effects of the present invention can be achieved by using the composition of the present invention.

In particular, it was confirmed that the effects of the present invention are superior when the inorganic material essentially contains only boron nitride and an inorganic ion trapping agent (see comparison of the results of Examples 5, 21, and 22, etc.).

It was confirmed that the effects of the present invention are even better when the composition contains surface-modified boron nitride (see comparison of the results of Examples 5, 24-28, and 54-58, etc.).

It was confirmed that the effects of the present invention are more excellent when the curing accelerator contains a compound containing a phosphorus atom or a phosphonium salt (see comparison of the results of Examples 2 to 5, etc.).
Furthermore, it was confirmed that the effects of the present invention are more excellent when the curing accelerator contains a compound represented by general formula (P3) (see comparison of the results of Examples 3, 59 to 65, etc.).

It was confirmed that the effect of the present invention is more excellent when the maleimide compound has two maleimide groups (see, for example, comparison of the results of Examples 3 and 51).
It was confirmed that the effects of the present invention are more excellent when the maleimide compound is a compound represented by general formula (1) in which m is 1, n is 1, and ^L1 is a divalent linking group having 3 to 15 carbon atoms (see comparison of the results of Examples 5 to 9, etc.).

It has been confirmed that the effects of the present invention are superior when the phenolic compound has a triazine skeleton and the total content of the phenolic compound having a triazine skeleton and the epoxy compound having a triazine skeleton is 5 to 80 mass% of the total content of all phenolic compounds and all epoxy compounds (see comparison of the results of Examples 5, 10 to 20, etc.).

It was confirmed that the effect of the present invention is better when the content of inorganic matter relative to the total solids content of the composition is 83 mass% or less (see comparison of the results of Examples 24 and 30, etc.).

It was confirmed that the effects of the present invention are better when the content of the maleimide compound is 100 mass% or less relative to the total content of the epoxy compound and the phenol compound (see, for example, a comparison of the results of Examples 24 and 29).

It was confirmed that the effects of the present invention are even better when the composition contains an ion scavenger (see comparison of the results of Examples 9, 31, and 32, etc.).

It has been confirmed that the effects of the present invention are superior when the ion scavenger in the composition is a composite of magnesium and aluminum or a composite of zirconium and bismuth (see comparison of Examples 9 and 31, comparison of the results of Examples 24, 33 to 36, etc.).

It was confirmed that the epoxy compound preferably contains a polyhydroxybenzene-type glycidyl ether, a bisphenol F-type glycidyl ether, a rod-shaped compound, a phenoxy resin, or a disc-shaped compound, in order to obtain a thermally conductive material having better moisture absorption suppression and solder heat resistance (see, for example, a comparison of the results of Examples 5, 11 to 20).
Furthermore, in order to obtain a thermally conductive material having better moisture absorption suppression and solder heat resistance, it was confirmed that when the epoxy compound contains an epoxy compound having a triazine ring as the central ring, the total content of the phenol compound having a triazine skeleton and the epoxy compound having a triazine skeleton is preferably 5 to 80 mass % of the total content of all phenol compounds and all epoxy compounds (see, for example, a comparison of the results of Example 10 and Example 20).

It was confirmed that when the molecular weight of the curing accelerator in the composition is 250 or more, solder heat resistance II is better, and when the molecular weight of the curing accelerator in the composition is 430 or more, solder heat resistance II is even better (see comparison of the results of Examples 2 to 5, 24, 29, 30, 59 to 75, etc.).

<<Test Y>>
Test Y (Example 76 and subsequent examples) was carried out under the conditions and procedures shown below.

[Preparation of Composition]
A solvent (cyclopentanone), a phenolic compound, an epoxy compound, an ion scavenger (if desired), a specific compound (maleimide compound), and a curing accelerator were mixed in this order, and then an inorganic substance or a surface-modified inorganic substance was added. The resulting mixture was treated for 5 minutes in a planetary centrifugal mixer (THINKY Corporation, Awatori Rentaro ARE-310) to obtain a composition (curable composition) for each example.

The amount of solvent added was such that the solid content of the composition was 42.5% by volume (in the range of 52 to 58% by mass in each case).
The solid content of each composition was adjusted within the above range so that the viscosity of each composition was approximately the same.
The total content of the epoxy compound and the phenol compound was adjusted to the amount shown in the "Total amount (mass%)" column in Table 2 relative to the total solid content of the composition, and the ratio of the total number of epoxy groups in the epoxy compound to the total number of hydroxyl groups in the phenol compound was adjusted to the ratio shown in the "(Epoxy/phenol) Functional group ratio" column in Table 2.
The solid content of the composition of Example 76 in Test Y was the same as the solid content of the composition of Example 11 in Test X.

[evaluation]
[Evaluation of thermal conductivity, Tg (heat resistance), and insulation]
The thermal conductivity, Tg (heat resistance), and insulating properties of the compositions of each example of Test Y were also tested and evaluated using the same methods and evaluation criteria as those shown in [Evaluation method of thermal conductivity], [Evaluation of Tg (heat resistance)], and [Evaluation of insulating properties] in Test X.

[Evaluation of handling properties (storage stability)]
Semi-cured sheets (semi-cured films) were prepared using the compositions of each example of Test Y in the same manner as in Test X (Preparation of Semi-Cured Sheets (Semi-Cured Films)).
The PET film was peeled off from the resulting semi-cured sheet, and the sheet was left to stand at room temperature (25° C.) for 1 hour immediately after preparation.
The semi-cured sheet was then cut into strips measuring 5 cm x 10 cm to prepare samples for bending tests, which were then allowed to stand at room temperature (25°C) for 23 hours.
After leaving the sample to stand, a bending test was carried out using a cylindrical mandrel testing machine (manufactured by Cortec Co., Ltd.) according to the method described in JIS K 5600-5-1. Cylindrical mandrels with diameters of 25 mm, 20 mm, and 16 mm were used, and the handleability of the semi-cured sheet 1 day after production (24 hours after production) was evaluated based on the diameter of the mandrel used in the bending test when the sample broke or was damaged, according to the following evaluation criteria.
The smaller the diameter of the mandrel used when the sample broke, the better the handling properties of the semi-cured sheet after storage over time.
The diameter of the mandrel at the time of breakage was classified according to the following criteria, and the handling properties (storability over time) were evaluated.
A+: No breakage at 25mm, 20mm and 16mm A: No breakage at 25mm and 20mm, breakage at 16mm B: No breakage at 25mm, breakage at 20mm and 16mm C: Breakage at 25mm, 20mm and 16mm

[result]
Table 2 is shown below.
Table 2 shows the solid content of the composition and the test results for each example.
In the table, in the "Type" column of epoxy compounds, when multiple types of epoxy compounds are used, the mass ratio of the contents of the respective epoxy compounds is shown in the format of "X/Y."
In the table, the column "Viscosity (mPa·s, 25° C.)" indicates the viscosity of the epoxy compound used at 25° C. The viscosity was measured by the method described in the specification.
The column "(Epoxy/Phenol) Functional Group Ratio" indicates the ratio of the total number of epoxy groups in the epoxy compounds to the total number of hydroxyl groups in the phenol compounds in the composition (total number of epoxy groups/total number of hydroxyl groups).

Test Y also confirmed that the use of the composition of the present invention makes it possible to form a thermally conductive material with excellent thermal conductivity and heat resistance. It was also confirmed that the thermally conductive material formed using the composition of the present invention also has excellent insulating properties.

Furthermore, it was confirmed that when the epoxy compound contains a low-viscosity epoxy compound, the handleability of the semi-cured film formed using the composition is superior.
(See comparison of the results of Examples 80 and 91.)

It was confirmed that, in terms of improving the heat resistance (Tg) of the obtained thermal conductive material, the epoxy compound is preferably an epoxy compound having an aromatic ring group or an epoxy compound represented by general formula (E3) in which X is an integer of 1 to 3, and more preferably an epoxy compound having an aromatic ring group.
(See comparison of results in Examples 77, 79, 88, and 90; comparison of results in Examples 80, 89, and 91, etc.).

It was confirmed that in order to obtain better thermal conductivity and/or insulating properties of the resulting thermal conductive material, the content of the maleimide compound is preferably 6 mass% or more relative to the total solid content of the composition (see, for example, a comparison of the results of Examples 77 and 78).

It was confirmed that, in terms of improving the handleability of the semi-cured film and/or the heat resistance (Tg) of the resulting thermal conductive material, the ratio of the total number of epoxy groups contained in the epoxy compound to the total number of hydroxyl groups contained in the phenol compound (number of epoxy groups/number of hydroxyl groups) is preferably 1.1/1.0 to 3.0/1.0, more preferably 1.2/1.0 to 2.0/1.0, and even more preferably 1.3/1.0 to 1.8/1.0.
(See comparison of results of Examples 85-87, comparison of results of Examples 77 and 84, comparison of results of Examples 78 and 85, etc.).

Claims (17)

phenolic compounds,
one or both of a maleimide compound having one or more maleimide groups and a cyanate compound having one or more cyanate groups;
Inorganic matter and
a curing accelerator ;
the inorganic material includes an inorganic nitride,
The curable composition , wherein the curing accelerator comprises a compound represented by general formula (P3) :
In formula (P3), R ^p31 to R ^p34 each independently represent a phenyl group which may have a substituent. The maleimide compound is contained,
The curable composition according to claim 1 , wherein the maleimide compound is a compound represented by general formula (1):
In the general formula (1), m represents 0 or 1.
n represents 0 or 1.
R ¹ and R ² each independently represent a hydrogen atom or a substituent.
^L1 represents a divalent linking group. The curable composition according to claim 2, wherein, in the general formula (1), m represents 1, n represents 1, and the divalent linking group represented by L ¹ has 3 to 15 carbon atoms. The maleimide compound is contained,
The curable composition according to any one of claims 1 to 3, wherein the maleimide compound has two maleimide groups. The curable composition according to any one of claims 1 to 4, wherein the inorganic material comprises boron nitride. The curable composition according to claim 5, wherein the boron nitride comprises aggregated boron nitride having an average particle size of 20 μm or more. Further, a surface modifier is included,
7. The curable composition according to claim 5, wherein the boron nitride, together with the surface modifier adsorbed onto the surface of the boron nitride, constitutes surface-modified boron nitride. The curable composition according to any one of claims 1 to 7, further comprising an epoxy compound. The maleimide compound is contained, and
The curable composition of claim 8 , wherein the epoxy compound comprises an epoxy compound having a viscosity at 25° C. of less than 1000 mPa·s. The maleimide compound is contained, and
10. The curable composition according to claim 8, wherein in the curable composition, a ratio of the total number of epoxy groups contained in the epoxy compound to the total number of hydroxyl groups contained in the phenol compound is 1.2/1.0 to 2.0/1.0. The curable composition according to any one of claims 8 to 10, satisfying at least one of the following requirements: the phenolic compound includes a phenolic compound having a triazine skeleton; and the epoxy compound includes an epoxy compound having a triazine skeleton. The curable composition according to any one of claims 1 to 11 , wherein the molecular weight of the curing accelerator is 430 or more. The curable composition according to any one of claims 1 to 12 , further comprising an ion scavenger. A thermally conductive material obtained by curing the curable composition according to any one of claims 1 to 13 . A thermally conductive sheet comprising the thermally conductive material according to claim 14 . The thermal conductive sheet according to claim 15 , wherein the mass change rate calculated by the following formula is less than 1.0%.
Mass change rate (%) = (W2 - W1) / W1 x 100
W1: Mass of the dry thermal conductive sheet after drying for 2 hours in an environment of 120°C. W2: Mass of the hygroscopic thermal conductive sheet after leaving the dry thermal conductive sheet in an environment of 85°C and 85% RH for 24 hours. A device with a thermally conductive layer, comprising: a device; and a thermally conductive layer comprising the thermally conductive sheet according to claim 15 or 16, disposed on the device.