JP2018162366A - Epoxy resin composition, resin sheet, b-stage sheet, c-stage sheet, cured product, resin coated metal foil, and metal substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an epoxy resin composition which is excellent in thermal conductivity, insulating property and adhesiveness at high temperature when it is made into a cured product while maintaining flexibility when it is made into A stage and B stage. Provided are a resin sheet, a B stage sheet, a C stage sheet, a cured product, a metal foil with a resin, and a metal substrate. SOLUTION: The epoxy resin, an amine-based curing agent and a filler are contained, the filler contains a nitride filler, and the epoxy resin has a structural unit represented by the following general formula (I) in one molecule. An epoxy resin composition containing two dimer compounds and having a nitride filler content of 42% by volume to 75% by volume. In the general formula (I), R1 to R4 independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [Selection diagram] None

Description

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

  Many electronic devices and electric devices ranging from generators and motors to printed wiring boards and IC (Integrated Circuit) chips include a conductor for conducting electricity and an insulating material. In recent years, the amount of heat generated has increased with the miniaturization of these devices. For this reason, how to dissipate heat in the insulating material is an important issue.

  As an insulating material used in these devices, a cured resin obtained by curing a thermosetting resin composition is widely used from the viewpoints of insulation and heat resistance. However, since the thermal conductivity of the cured resin is generally low and is a major factor hindering heat dissipation, development of a cured resin having high thermal conductivity is desired.

  As a technique for increasing the thermal conductivity of the cured resin, a polyfunctional epoxy compound having three or more epoxy groups in one molecule, and an inorganic filler (A) that is an aggregate of primary particles having a specific particle diameter; And a thermosetting resin composition containing a specific ratio of the inorganic filler (c) and the inorganic filler (B) containing the inorganic filler (b) each having a particle diameter of a single particle in a specific range. (For example, refer to Patent Document 1). In Patent Document 1, by adopting the above-described configuration, the inorganic filler (c) and the inorganic filler (b) fill a gap between the inorganic filler (A), which is an aggregate of primary particles, and a heat flow path is formed. Therefore, it is said that the heat dissipation characteristics are improved.

  Moreover, the hardened | cured material of the composition containing the epoxy compound which has a mesogen skeleton in a molecule | numerator is proposed as resin hardened | cured material which has high heat conductivity (for example, refer patent document 2). Examples of the epoxy resin having a mesogen skeleton in the molecule include compounds disclosed in Patent Documents 3 to 5 and the like.

  Moreover, as a technique for achieving high thermal conductivity, there is a method of filling a resin composition with an inorganic filler made of ceramics having high thermal conductivity to make a composite material. Known ceramics having high thermal conductivity include alumina, boron nitride, aluminum nitride, silica, magnesium oxide, silicon nitride, silicon carbide, and the like. By filling the resin composition with an inorganic filler that achieves both thermal conductivity and insulation, it is possible to achieve both thermal conductivity and insulation in the composite material.

  In addition, from the viewpoint of achieving both high thermal conductivity and high insulation, it contains an epoxy resin having a mesogenic skeleton and a mixed filler of α-alumina and boron nitride, and the content of α-alumina in all fillers An epoxy resin composition having a volume of 50% to 90% by volume has been proposed (see, for example, Patent Document 6).

  In addition, as a technique for increasing thermal conductivity, it has recently been proposed to use boron nitride as a filler (see, for example, Patent Document 7). Boron nitride is also excellent in insulation.

Japanese Patent Laying-Open No. 2015-189884 Japanese Patent No. 4118691 Japanese Patent No. 4619770 Japanese Patent No. 5471975 JP 2011-84557 A Japanese Patent Laid-Open No. 2006-155985 Japanese Patent No. 5348332

  However, in Patent Document 1, since a polyfunctional epoxy compound having three or more epoxy groups in one molecule tends to be a rigid skeleton, flexibility may be inferior when the A stage and the B stage are used. . As a result, the A-stage and B-stage sheets may not be wound, and productivity on a large scale may be reduced. Further, since the sheets of the A stage and the B stage are brittle, there may be a problem in quality. Further, the thermal conductivity is not sufficiently high, and further improvement is necessary.

  Moreover, since the epoxy resin which has a mesogen skeleton of patent document 6 generally has high crystallinity, it is inferior to the flexibility at the time of using A stage and B stage. Further, since most of the filler is α-alumina, the thermal conductivity when cured is low, and further improvement is necessary.

  Further, due to the fact that the shape of boron nitride is scaly, the composition containing boron nitride described in Patent Document 7 has a tendency to decrease in fluidity and formability, and to be cured. The peel strength (adhesive strength) from the metal foil tends to decrease.

  It is also conceivable to increase the filling of the inorganic filler in order to increase the thermal conductivity. However, in this case, the adhesive strength is reduced, and peeling may occur due to thermal shock such as reflow or heat cycle, which may significantly reduce the insulation.

  In view of the above problems, the present invention is an epoxy resin composition that is excellent in thermal conductivity, insulation, and adhesiveness at high temperatures when it is made into a cured product while maintaining flexibility when it is set as A stage and B stage. It is an object to provide an article and a resin sheet, a B stage sheet, a C stage sheet, a cured product, a metal foil with resin, and a metal substrate using the same.

Means for solving the above problems include the following embodiments.
<1> An epoxy resin, an amine-based curing agent, and a filler are contained, the filler contains a nitride filler, and the epoxy resin contains 2 structural units represented by the following general formula (I) in one molecule. The epoxy resin composition which contains the dimer compound which has two, and the content rate of the said nitride filler is 42 volume%-75 volume%.

[In General Formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently. ]
<2> The epoxy resin composition according to <1>, wherein a proportion of the dimer compound in the epoxy resin is 15% by mass to 28% by mass.
<3> The dimer compound has at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB). <1> or the epoxy resin composition according to <2>.

[In General Formula (IA) and General Formula (IB), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents 1 to 8 carbon atoms. Represents an alkyl group. n shows the integer of 0-4. ]
<4> The structural unit represented by the general formula (IA) includes a structural unit represented by the following general formula (IA-1) and a structural unit represented by the following general formula (IA-2). The epoxy resin composition according to <3>, comprising at least one structural unit selected.

[In General Formula (IA-1) and General Formula (IA-2), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ]
<5> The structural unit represented by the general formula (IB) includes a structural unit represented by the following general formula (IB-1) and a structural unit represented by the following general formula (IB-2). The epoxy resin composition according to <3> or <4>, comprising at least one selected structural unit.

[In General Formula (IB-1) and General Formula (IB-2), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ]
<6> The dimer compound is represented by the following general formula (II-A), the following general formula (II-B), and the following general formula (II-C). The epoxy resin composition according to any one of <1> to <5>, comprising at least one compound selected from the group consisting of compounds.


[In General Formula (II-A) to General Formula (II-C), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ]
<7> The dimer compound is a compound represented by the following general formula (II-A-1), a compound represented by the following general formula (II-B-1), and the following general formula (II-C- <1>-<6> The epoxy resin composition according to any one of <1> to <6>, comprising at least one compound selected from the group consisting of compounds represented by 1).

[In General Formula (II-A-1) to General Formula (II-C-1), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ represents Independently, an alkyl group having 1 to 8 carbon atoms is shown. n shows the integer of 0-4. ]
<8> The epoxy resin composition according to any one of <1> to <7>, wherein the epoxy resin includes an epoxy compound represented by the following general formula (III).


[In General Formula (III), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently. ]
<9> The epoxy resin composition according to <8>, wherein a ratio of the epoxy compound represented by the general formula (III) in the epoxy resin is 57% by mass to 80% by mass.
<10> The epoxy resin composition according to any one of <1> to <9>, wherein the filler content is 50% by volume to 90% by volume.
<11> The epoxy according to any one of <1> to <10>, wherein the amine-based curing agent includes at least one selected from the group consisting of amine-based curing agents having a benzene ring or a naphthalene ring. Resin composition.
<12> A resin sheet having a resin composition layer containing the epoxy resin composition according to any one of <1> to <11>.
<13> A B stage sheet having a semi-cured resin composition layer containing a semi-cured product of the epoxy resin composition according to any one of <1> to <11>.
<14> A C stage sheet having a cured resin composition layer containing a cured product of the epoxy resin composition according to any one of <1> to <11>.
<15> A cured product of the epoxy resin composition according to any one of <1> to <11>.
<16> A metal foil and a semi-cured resin composition layer including a semi-cured product of the epoxy resin composition according to any one of <1> to <11> disposed on the metal foil. Metal foil with resin.
<17> A metal support, a cured resin composition layer containing a cured product of the epoxy resin composition according to any one of <1> to <11> disposed on the metal support, and the curing A metal board comprising: a metal plate disposed on the resin composition layer.

  According to the present invention, an epoxy resin composition excellent in thermal conductivity, insulation, and adhesiveness at high temperatures when cured is maintained while maintaining flexibility when the A stage and the B stage are used. A resin sheet, a B stage sheet, a C stage sheet, a cured product, a metal foil with resin, and a metal substrate can be provided.

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

In the present disclosure, the numerical ranges indicated using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical description. . Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.
In the present disclosure, each component may contain a plurality of corresponding substances. When multiple types of substances corresponding to each component are present in the composition, the content or content of each component is the total content or content of the multiple types of substances present in the composition unless otherwise specified. Means quantity.
In the present disclosure, a plurality of particles corresponding to each component may be included. When a plurality of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of particles present in the composition unless otherwise specified.
In the present disclosure, the term “layer” refers to a case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. included.
In the present disclosure, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.
In the present disclosure, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. .

<Epoxy resin composition>
The epoxy resin composition of the present disclosure contains an epoxy resin, an amine-based curing agent, and a filler, the filler includes a nitride filler, and the epoxy resin is represented by the following general formula (I) in one molecule. A dimer compound having two structural units, wherein the content of the nitride filler is 42% by volume to 75% by volume.

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

  The epoxy resin composition of the present disclosure having such a configuration maintains thermal flexibility when used as an A stage and a B stage, and has thermal conductivity, insulating properties, and high temperatures when used as a cured product such as a C stage. Excellent adhesion at. The epoxy resin composition of the present disclosure may further contain other components as necessary.

Regarding the A stage, the B stage, and the C stage in the present disclosure, the provisions of JIS K6900: 1994 are referred to. In the A stage, it is soluble in a specific solvent and fusible. In the B stage, the viscosity is 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 ° C.), whereas the viscosity decreases to 10 ² Pa · s to 10 ³ Pa · s at 100 ° C. It is preferable to do. In the C stage, it does not melt even by heating. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min).

In the present disclosure, examples of the A stage include a resin composition layer and a resin sheet, and examples of the B stage include a semi-cured product, a semi-cured resin composition layer, a B stage sheet, and the like. Examples of the stage include a cured product, a cured resin composition layer, and a C stage sheet.
Hereinafter, each component which comprises the epoxy resin composition of this indication is demonstrated.

<Epoxy resin>
The epoxy resin contains a dimer compound having two structural units represented by the following general formula (I) in one molecule (hereinafter sometimes abbreviated as “dimer compound”).

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

In general formula (I), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, A methyl group is more preferred, and a hydrogen atom is still more preferred.
Furthermore, two to four of R ^{1 to} R ⁴ are preferably hydrogen atoms, more preferably three or four are hydrogen atoms, and all four are further hydrogen atoms. preferable. When any of R ^{1 to} R ⁴ is an alkyl group having 1 to 3 carbon atoms, at least one of R ¹ and R ⁴ is preferably an alkyl group having 1 to 3 carbon atoms.

  The dimer compound preferably has at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB).

In the general formula (IA) and Formula ^(IB), in each of R 1 to R ⁴ independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, each ^{R 5} is independently, 1 to 8 carbon atoms An alkyl group is shown. n shows the integer of 0-4. ]

Specific examples of ^R 1 to R ⁴ in the general formula (IA) and Formula (IB) is the same as ^R 1 to R ⁴ in the general formula (I), the same applies to its preferred range.

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

  The structural unit represented by the general formula (IA) is at least selected from the group consisting of the structural unit represented by the following general formula (IA-1) and the structural unit represented by the following general formula (IA-2). It preferably includes one structural unit, and more preferably includes a structural unit represented by the following general formula (IA-1).

  The structural unit represented by the general formula (IB) is at least selected from the group consisting of the structural unit represented by the following general formula (IB-1) and the structural unit represented by the following general formula (IB-2). It preferably includes one structural unit, and more preferably includes a structural unit represented by the following general formula (IB-1).

Specific examples of R ^{1 to} R ⁵ and n in General Formula (IA-1), General Formula (IA-2), General Formula (IB-1), and General Formula (IB-2) include General Formula (IA) and It is the same as R ^{1 to} R ⁵ and n in the general formula (IB), and its preferred range is also the same.

  Specific examples of the dimer compound include a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and the following general formula (II-C). Compounds and the like. The dimer compound is a group consisting of a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and a compound represented by the following general formula (II-C). It is preferable to include at least one compound selected from the above.

Specific examples of the general formula (II-A), general formula (II-B) and formula (II-C) in ^R 1 to R ⁵ and n have the general formula (IA) and ^{R 1} in the general formula (IB) is the same as to R ⁵ and n, is the same preferred ranges thereof.

  The compound represented by the general formula (II-A) preferably includes a compound represented by the following general formula (II-A-1) and a compound represented by the following general formula (II-A-2). More preferably, a compound represented by the following general formula (II-A-1) is included.

  The compound represented by the general formula (II-B) preferably includes a compound represented by the following general formula (II-B-1) and a compound represented by the following general formula (II-B-2). More preferably, a compound represented by the following general formula (II-B-1) is included.

  The compound represented by the general formula (II-C) preferably includes a compound represented by the following general formula (II-C-1) and a compound represented by the following general formula (II-C-2). It is more preferable that the compound represented by the following general formula (II-C-1) is included.

General formula (II-A-1), general formula (II-A-2), general formula (II-B-1), general formula (II-B-2), general formula (II-C-1) and specific examples of ^R 1 to R ⁵ and n in the general formula (II-C-2) is the same as ^R 1 to R ⁵ and n in the general formula (IA) and formula (IB), also the preferred ranges It is the same.

  The dimer compound includes a compound represented by the general formula (II-A-1), a compound represented by the general formula (II-B-1), and a compound represented by the general formula (II-C-1). It is preferable to include at least one compound selected from the group consisting of:

  The structure of these dimer compounds is an epoxy compound represented by the following general formula (III) used when synthesizing an epoxy resin, and a divalent phenol having two hydroxyl groups as substituents on one benzene ring. Compare the molecular weight of the structure estimated to be obtained from the reaction of the compound with the molecular weight of the target compound determined by liquid chromatography using a liquid chromatograph equipped with a UV spectrum detector and a mass spectrum detector. Can be determined.

  In liquid chromatography, for example, “LaChrom II C18” manufactured by Hitachi, Ltd. is used as an analytical column, tetrahydrofuran is used as an eluent, and measurement is performed at a flow rate of 1.0 ml / min. The UV spectrum detector detects the absorbance at a wavelength of 280 nm. The mass spectrum detector detects with an ionization voltage of 2700V. Details of the synthesis method and evaluation of the epoxy resin will be described later.

  The proportion of the dimer compound in the epoxy resin is preferably 15% by mass to 28% by mass, more preferably 20% by mass to 27% by mass, and 22% by mass to 25% by mass. Further preferred.

  When the proportion of the dimer compound is 15% by mass or more, the handling properties such as flexibility tend to be excellent when the A stage and the B stage are used. Moreover, when the ratio of the dimer compound is 28% by mass or less, a decrease in the crosslinking density is suppressed when a cured product is obtained, and the thermal conductivity and glass transition temperature (Tg) of the obtained cured product are maintained high. Tend to.

  The proportion of the dimer compound in the epoxy resin can be determined by reverse phase chromatography (RPLC) measurement described later.

The epoxy resin may also contain a multimeric compound having 3 or more structural units represented by the general formula (I) (hereinafter sometimes abbreviated as “multimeric compound”). The number of structural units represented by general formula (I) in the multimeric compound is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less as an average value.
The multimeric compound is preferably a multimeric compound having at least one structural unit selected from the group consisting of a structural unit represented by the general formula (IA) and a structural unit represented by the following general formula (IB). .
The structural unit represented by the general formula (IA) in the multimeric compound is selected from the group consisting of the structural unit represented by the general formula (IA-1) and the structural unit represented by the following general formula (IA-2) It is preferable to include at least one structural unit, and it is more preferable to include a structural unit represented by the general formula (IA-1).
The structural unit represented by the general formula (IB) in the multimeric compound is selected from the group consisting of the structural unit represented by the general formula (IB-1) and the structural unit represented by the general formula (IB-2). It is preferable that at least one structural unit is included, and it is more preferable that the structural unit represented by the general formula (IB-1) is included.

  The epoxy resin may contain an epoxy compound represented by the following general formula (III).

In general formula (III), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.
Incidentally, specific examples of ^R 1 to R ⁴ in the general formula (III) is the same as ^R 1 to R ⁴ in the general formula (I), the same applies to its preferred range.

  The proportion of the epoxy compound represented by the general formula (III) in the epoxy resin is preferably 57% by mass to 80% by mass, more preferably 59% by mass to 74% by mass, and 62% by mass to More preferably, it is 70 mass%.

  When the ratio of the epoxy compound is 57% by mass or more, when a cured product is obtained, the crosslinking density is unlikely to decrease and the thermal conductivity and Tg tend to be excellent. On the other hand, when the ratio of the epoxy compound is 80% by mass or less, handling properties such as flexibility when the A stage and the B stage are used tend to be excellent.

  Like the epoxy compound represented by the general formula (III), an epoxy compound having a mesogenic group in the molecular structure is generally easily crystallized and tends to have a higher melting temperature than a general-purpose epoxy compound. However, crystallization is suppressed by partially polymerizing such an epoxy compound to obtain a compound containing a dimer compound. As a result, the handling properties when the A stage and the B stage are set tend to be improved.

  The epoxy resin may contain other epoxy resins in addition to the dimer compound, the multimeric compound, and the epoxy compound represented by the general formula (III). The proportion of the other epoxy resin in the epoxy resin is preferably less than 15% by mass, more preferably 10% by mass or less, further preferably 8% by mass or less, and 5% by mass or less. Particularly preferred is 2% by mass or less.

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

The epoxy equivalent of the epoxy resin is preferably 245 g / eq to 300 g / eq from the viewpoint of achieving both the handling properties when the A stage and the B stage are used and the thermal conductivity when the cured product is used, and 250 g / eq. It is more preferably eq to 290 g / eq, and further preferably 260 g / eq to 280 g / eq. When the epoxy equivalent of the epoxy resin is 245 g / eq or more, the crystallinity of the epoxy resin does not become too high, so that the handling property when the A stage and the B stage are used tends to be difficult to deteriorate. On the other hand, when the epoxy equivalent of the epoxy resin is 300 g / eq or less, the crosslink density of the epoxy resin is difficult to decrease, and thus the thermal conductivity when cured is increased.
The epoxy equivalent of the epoxy resin is measured by a perchloric acid titration method.

  In addition, the number average molecular weight (Mn) in the gel permeation chromatography (GPC) measurement of the epoxy resin is from the viewpoint of achieving both the handling properties when the A stage and the B stage are used and the thermal conductivity when the cured product is used. 400 to 800, preferably 450 to 750, and more preferably 500 to 700. When the Mn of the epoxy resin is 400 or more, the crystallinity of the epoxy resin does not become too high, and the handling properties when the A stage and the B stage are made tend not to be lowered. When the Mn of the epoxy resin is 800 or less, the crosslink density of the epoxy resin is difficult to decrease, so that the thermal conductivity when it is a cured product tends to increase.

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

  An epoxy resin containing a dimer compound includes, for example, an epoxy compound represented by the general formula (III), a dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring, and a curing catalyst described later as a synthetic solvent. It can be synthesized by dissolving in and stirring with heating. Although the synthesis is possible even by a technique in which an epoxy compound is melted and reacted without using a solvent, it may be necessary to raise the temperature to a temperature at which the epoxy compound melts. For this reason, the synthesis method using a synthetic solvent is preferable from the viewpoint of safety.

The synthetic solvent is a solvent that can be heated to a temperature necessary for the reaction between the epoxy compound represented by the general formula (III) and a dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring. If there is, there is no particular limitation.
Specific examples include cyclohexanone, cyclopentanone, ethyl lactate, propylene glycol monomethyl ether, N-methylpyrrolidone and the like.

  The amount of the synthetic solvent is not less than an amount capable of dissolving the epoxy compound represented by the general formula (III), the dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring and the curing catalyst at the reaction temperature. . Although the solubility varies depending on the type of raw material, the type of solvent, and the like before the reaction, if the charged solid content concentration is 20% by mass to 60% by mass, the resin solution viscosity after synthesis tends to be in a preferable range.

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

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

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

  The amount of the curing catalyst is not particularly limited, and from the viewpoint of reaction rate and storage stability, an epoxy compound represented by the general formula (III) and a divalent phenol having two hydroxyl groups as substituents on one benzene ring. It is preferable that it is 0.1 mass%-1.5 mass% with respect to the total mass with a compound, and it is more preferable that it is 0.2 mass%-1 mass%.

The epoxy resin containing the binary compound can be synthesized using a glass flask if it is a small scale, and using a stainless steel synthesis pot if it is a large scale. A specific synthesis method is as follows, for example.
First, the epoxy compound represented by the general formula (III) is put into a flask or a synthesis kettle, a synthesis solvent is added, and the mixture is heated to a reaction temperature with an oil bath or a heating medium to dissolve the epoxy compound. A dihydric phenol compound having two hydroxyl groups as substituents in one benzene ring is added thereto, and after confirming that the compound is dissolved in the synthesis solvent, a curing catalyst is added to start the reaction. If the reaction solution is taken out after a predetermined time, an epoxy resin solution containing a dimer compound can be obtained. In addition, if the synthetic solvent is distilled off under reduced pressure under a heating condition in a flask or a synthesis kettle, an epoxy resin containing a dimer compound is obtained as a solid at room temperature (25 ° C.).

  The reaction temperature is not limited as long as the reaction between the epoxy group and the phenolic hydroxyl group proceeds in the presence of the curing catalyst, and is preferably in the range of 100 ° C to 180 ° C, for example, 100 ° C to 150 ° C. More preferably, it is the range. By setting the reaction temperature to 100 ° C. or higher, the time until the reaction is completed tends to be shortened. On the other hand, by setting the reaction temperature to 180 ° C. or lower, the possibility of gelation tends to be reduced.

  In the synthesis of an epoxy resin containing a dimer compound, the ratio between the epoxy compound represented by the general formula (III) and the divalent phenol compound having two hydroxyl groups as substituents on one benzene ring was changed. Can be synthesized. Specifically, the equivalent number (Ep) of the epoxy group of the epoxy compound represented by the general formula (III) and the phenolic hydroxyl group of the dihydric phenol compound having two hydroxyl groups as substituents on one benzene ring. The ratio (Ep / Ph) with the number of equivalents (Ph) can be synthesized as a range of 100/100 to 100/1. Ep / Ph is preferably in the range of 100/18 to 100/10 from the viewpoints of handling properties when A stage and B stage are used, and heat resistance and thermal conductivity when cured. When Ep / Ph is set to 100/10 or less, a decrease in crosslinking density is suppressed, and heat resistance and thermal conductivity when cured are improved. On the other hand, when Ep / Ph is set to 100/18 or more, the crystallinity of the resulting epoxy resin is lowered, and the handling properties when the A stage and the B stage are obtained tend to be improved.

  Moreover, the epoxy resin represented by a dimer compound, a multimeric compound, and general formula (III) has a mesogenic group in molecular structure. Patent Document 1 describes that a cured product of an epoxy resin having a mesogenic group in the molecular structure is excellent in thermal conductivity. In addition, in International Publication No. 2013/065159, high thermal conductivity is obtained when a cured product is obtained by combining a novolak resin in which a divalent phenol compound is novolaked with an epoxy compound represented by the general formula (III). It is described that a high Tg can be realized.

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

  Furthermore, the epoxy compound represented by the general formula (III) forms a higher order structure having higher ordering with a filler as a center, and the thermal conductivity of the cured product is remarkably improved. / 065159. This is also true for epoxy resins containing dimer compounds. This is considered because an efficient heat conduction path is formed when the higher order structure is generated with the filler as a base point.

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

In addition, formation of the higher order structure in the hardened | cured material containing a filler can be confirmed as follows.
A composition is prepared by adding 5% by volume to 10% by volume of a filler such as boron nitride filler to a mixture of an epoxy resin, a curing agent, and a curing catalyst, and the composition is cured to obtain a cured product (thickness: 0.00). 1-20 μm). The obtained cured product is sandwiched between slide glasses (thickness: about 1 mm) and observed with a polarizing microscope (for example, “BX51” manufactured by Olympus Corporation). In the area where the filler is present, an interference pattern is observed around the filler, but in the area where the filler is not present, no interference pattern is observed. This shows that the cured product of the epoxy resin forms a higher order structure with the filler as the center.

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

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

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

<Amine-based curing agent>
The epoxy resin composition contains an amine curing agent. One amine curing agent may be used alone, or two or more amine curing agents may be used in combination.

  As the amine curing agent, those usually used can be used without particular limitation, and those commercially available may be used. Among these, from the viewpoint of heat resistance, it is preferable to use an amine curing agent having a benzene ring or a naphthalene ring, and it is more preferable to use an amine curing agent having an amino group on the benzene ring or naphthalene ring. From the viewpoint of curability, it is preferable to use a polyfunctional amine-based curing agent having two or more amino groups.

  Examples of amine curing agents include 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 4 , 4′-diaminodiphenyl ether, 4,4′-diamino-3,3′-dimethoxybiphenyl, 4,4′-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,2-phenylene Diamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 4,4'-diaminobenzanilide, 3,3'-diaminobenzanilide, trimethylene-bis-4-aminobenzoate, 1,4-diaminonaphthalene And 1,8-diaminonaphthalene. When a liquid amino curing agent such as 3,3′-diethyl-4,4′-diaminodiphenylmethane is used at room temperature (25 ° C.), before and after the high-temperature treatment even if the pressing pressure when producing a cured product is lowered. It tends to be excellent in adhesion and insulation. The liquid state at normal temperature (25 ° C.) specifically means that the viscosity measured with an E-type viscometer is 1000 Pa · s or less at 25 ° C. The above viscosity is measured using an E-type viscometer EHD type (cone angle 3 °, cone diameter 28 mm), measurement temperature: 25 ° C., sample volume: 0.7 ml, and the number of rotations assumed for the sample with reference to the following. The value after 1 minute from the start of measurement is taken as the measurement value.

  The content of the amine curing agent is not particularly limited. From the viewpoint of efficiently carrying out the curing reaction, the ratio of the number of equivalents of active hydrogen in the amine curing agent to the number of equivalents of epoxy groups in the epoxy resin (number of equivalents of active hydrogen / number of equivalents of epoxy group) is 0. .3 to 3.0 is preferable, and 0.5 to 2.0 is more preferable.

<Filler>
The epoxy resin composition contains a filler. The filler includes at least a nitride filler from the viewpoint of thermal conductivity. The content of the nitride filler in the epoxy resin composition is 42% to 75% by volume, preferably 45% to 75% by volume, and more preferably 48% to 75% by volume. .
When the content of the nitride filler is 42% by volume or more, the thermal conductivity tends to be excellent, and when it is 75% by volume or less, the flexibility of the A stage and the B stage tends to be excellent.

  Examples of the material for the nitride filler include boron nitride, silicon nitride, and aluminum nitride. The material of the nitride filler is preferably at least one of boron nitride and aluminum nitride from the viewpoint of thermal conductivity, and more preferably boron nitride from the viewpoint of insulation.

  In addition, whether the nitride filler is contained in the epoxy resin composition or a semi-cured product or a cured product thereof can be confirmed by, for example, energy dispersive X-ray analysis (EDX). By combining a scanning electron microscope (SEM) and EDX, it is also possible to confirm the distribution state of the nitride filler in the cross section of the epoxy resin composition or a semi-cured product or a cured product thereof.

  When boron nitride is used as the material of the nitride filler, the crystal form of boron nitride may be any of hexagonal, cubic, and rhombohedral, and the particle size is controlled. From the viewpoint of ease of processing, hexagonal crystals are preferable. Moreover, you may use together 2 or more types of boron nitride from which a crystal form differs.

  From the viewpoint of adjusting the thermal conductivity when cured and the viscosity of the epoxy resin composition, the nitride filler is preferably pulverized or agglomerated. Examples of the shape of the nitride filler include round shape, spherical shape, and scale shape. The nitride filler may be aggregated particles in which these particles are aggregated. From the viewpoint of increasing the filling property of the nitride filler, the ratio of the major axis to the minor axis (major axis / minor axis, aspect ratio) of the particles is preferably 3 or less, more preferably an aspect ratio. Is round or spherical with 2 or less, more preferably spherical.

  The aspect ratio of the particles means a value obtained by imaging particles using an electron microscope or the like, measuring the major axis and minor axis of each particle, and calculating the arithmetic average of the ratio of the major axis to the minor axis. In the present disclosure, the major axis of the particle refers to the length of the long side of the circumscribed rectangle of the particle, and the minor axis of the particle refers to the length of the short side of the circumscribed rectangle of the particle. The term “spherical particles” means that the aspect ratio is 1.5 or less.

Among these, as the nitride filler, agglomerated hexagonal boron nitride particles are preferable. The agglomerated hexagonal boron nitride particles have a large number of gaps, so that they are easily crushed and deformed when pressure is applied. Therefore, even if the filler content in the epoxy resin composition is reduced in consideration of applicability, it is possible to increase the substantial filler content by compressing the formed coating film. From the viewpoint of easy formation of a heat conduction path by contact between fillers having high thermal conductivity, the filler particle shape is preferably rounder or scale-like than spherical because the number of contact points of the particles is more preferable. However, spherical particles are preferred from the viewpoints of filler filling properties, thixotropic properties of the epoxy resin composition, and viscosity.
In the present disclosure, nitride fillers having different particle shapes may be used alone or in combination of two or more.

  The volume average particle diameter (D50) of the nitride filler is not particularly limited, and is preferably 100 μm or less from the viewpoint of moldability, and the thermal conductivity when cured and the thixotropic property of the epoxy resin composition. From the viewpoint, the thickness is more preferably 20 μm to 100 μm, and from the viewpoint of insulation, it is further preferably 20 μm to 60 μm.

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

  The filler may exhibit a particle size distribution having a single peak or may exhibit a particle size distribution having two or more peaks. From the viewpoint of the filling rate, the filler is preferably a filler showing a particle size distribution having two or more peaks, and more preferably a filler showing a particle size distribution having three or more peaks.

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

  The particle size distribution of the filler refers to a volume cumulative particle size distribution measured using a laser diffraction method. Moreover, the average particle diameter of a filler means the particle diameter (D50) from which volume cumulative particle size distribution measured using a laser diffraction method will be 50%. For particle size distribution measurement using the laser diffraction method, a laser diffraction / scattering particle size distribution measuring apparatus (for example, “LS13” manufactured by Beckman Coulter, Inc.) can be used. The filler dispersion for measurement can be obtained by introducing a filler into a 0.1% by mass sodium metaphosphate aqueous solution, ultrasonically dispersing the filler, and adjusting the concentration to an appropriate light amount in terms of device sensitivity. From the measured volume cumulative particle size distribution, it is determined whether the filler exhibits a particle size distribution having a single peak or a particle size distribution having two or more peaks.

  When a filler contains a 1st filler, a 2nd filler, and a 3rd filler, it is preferable to use a nitride filler as a 3rd filler. The first filler and the second filler may be nitride fillers or other fillers. The material of the first filler and the second filler is preferably at least one of aluminum nitride and aluminum oxide from the viewpoint of thermal conductivity when cured.

  The content of the filler in the epoxy resin composition is preferably 50% by volume to 90% by volume from the viewpoint of moldability, and 60% by volume from the viewpoint of thermal conductivity when a cured product is obtained. It is more preferably 85% by volume, and from the viewpoint of thixotropy of the epoxy resin composition, it is more preferably 65% by volume to 78% by volume. When the content of the filler is within the above range, it has flexibility before curing and tends to be excellent in thermal conductivity and insulation after curing.

The proportion of the nitride filler in the filler is preferably 10% by volume to 100% by volume from the viewpoint of insulation, and 20% by volume to 90% by volume from the viewpoint of thixotropic properties of the epoxy resin composition. More preferably, it is more preferably 30% by volume to 85% by volume from the viewpoint of thermal conductivity when a cured product is obtained.
As another aspect, the proportion of the nitride filler in the filler is preferably 50% by volume to 95% by volume, and from the viewpoint of filling properties, it is more preferably 60% by volume to 95% by volume, and curing. From the viewpoint of thermal conductivity when used as a product, it is more preferably 65% by volume to 92% by volume.

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

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

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

  Moreover, it does not specifically limit as content on the mass reference | standard of a filler. Specifically, when the epoxy resin composition is 100 parts by mass, the filler content is preferably 1 part by mass to 99 parts by mass, and more preferably 50 parts by mass to 97 parts by mass. 70 parts by mass to 95 parts by mass is more preferable. When the content of the filler is within the above range, the thermal conductivity of the cured product tends to be further improved.

<Other ingredients>
The epoxy resin composition may contain other components in addition to the above components, if necessary. Examples of other components include a solvent, an elastomer, a silane coupling agent, a dispersant, and an anti-settling agent. These components may be used individually by 1 type, respectively, and may use 2 or more types together.

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

  The epoxy resin composition preferably contains a silane coupling agent. By including a silane coupling agent, the thermal conductivity and insulation properties of the cured product tend to be further improved.

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

Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxy. Propylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) Aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-ureidopropyltriethoxysilane It is possible. Moreover, the silane coupling agent oligomer represented by SC-6000KS2 (made by Hitachi Chemical Techno Service Co., Ltd.), etc. are also mentioned.
These silane coupling agents may be used alone or in combination of two or more.

  When the epoxy resin composition contains a silane coupling agent, the content of the silane coupling agent in the epoxy resin composition is not particularly limited. For example, it is preferable that it is 0.01 mass%-0.1 mass% in solid content of an epoxy resin composition.

  The silane coupling agent should just be contained in the epoxy resin composition, and may exist in the state which coat | covered the surface of a filler, or may exist separately from a filler.

  The method for adding the silane coupling agent to the epoxy resin composition is not particularly limited. Specifically, an integral method that is added when mixing other materials such as epoxy resins, amine curing agents, fillers, and other materials used as needed, a certain amount of silane coupling to a small amount of epoxy resin After mixing the agent, the master batch method to mix with other materials such as filler, before mixing with other materials such as epoxy resin, the filler and silane coupling agent are mixed and silane coupling to the filler surface in advance There is a pretreatment method for treating the agent. In addition, the pretreatment method includes a dry method in which a stock solution or solution of a silane coupling agent is dispersed together with a filler by high-speed stirring, and the filler is slurried with a dilute solution of the silane coupling agent. The filler is used as a silane coupling agent. There are wet methods such as silane coupling agent treatment on the filler surface by immersion.

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

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

Furthermore, the silicon atom derived from the silane coupling agent present on the surface of the filler can be quantitatively measured by ²⁹ Si CP / MAS (Cross Polarization) / (Magic Angle Spinning) solid-state NMR (Nuclear Magnetic Resonance). Since this CP / MAS solid-state NMR (as an apparatus, for example, “JNM-ECA700” manufactured by JEOL Ltd.) has high resolution, even when the filler contains silica, the silica-derived silicon atom and silane cup as filler It is possible to distinguish silicon atoms derived from ring agents.
Further, when silica is not contained in the filler, silicon atoms derived from the silane coupling agent can be quantified also by a fluorescent X-ray analyzer (for example, “Supermini 200” manufactured by Rigaku Corporation).

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

<Physical properties of epoxy resin composition>
When the epoxy resin composition contains a solvent, the viscosity of the epoxy resin composition at 25 ° C. is preferably 0.5 Pa · s to 5 Pa · s, and preferably 0.5 Pa · s to 4 Pa · s. More preferably, it is 1 Pa · s to 3 Pa · s. The viscosity at 25 ° C. of the epoxy resin composition was measured at a temperature of 25 ° C. at a shear rate of 5.0 s ⁻¹ using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0 °). Value.
Moreover, it is preferable that the fluctuation index in 25 degreeC of an epoxy resin composition is 3-15, It is more preferable that it is 3.5-10, It is further more preferable that it is 4-7.
First, when the temperature of the epoxy resin composition is 25 ° C., the viscosity (η1) at a shear rate of 0.5 s ⁻¹ and the viscosity at a shear rate of 5.0 s ⁻¹ are used. (Η2) is measured, and (η1) / (η2) is calculated to obtain a value. Specifically, the “thickening index” is measured as a shear viscosity at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0 °).

<Resin sheet>
The resin sheet of this indication has a resin composition layer containing the epoxy resin composition of this indication. The resin composition layer may be one layer or two or more layers. The resin sheet of the present disclosure may further include a release film as necessary.

  For example, the resin composition layer is prepared by removing a varnish-like epoxy resin composition (hereinafter also referred to as “resin varnish”) prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition. It can be manufactured by applying on a mold film and drying.

  Application | coating of a resin varnish can be implemented by a well-known method. Specific examples include methods such as comma coating, die coating, lip coating, and gravure coating. Examples of a method for applying a resin varnish for forming a resin composition layer with a predetermined thickness include a comma coating method in which an object to be coated is passed between gaps, and a die coating method in which a resin varnish with a flow rate adjusted from a nozzle is applied. Can be mentioned. When the thickness of the resin composition layer before drying is 50 μm to 500 μm, it is preferable to use a comma coating method.

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

The density of the resin composition layer is not particularly limited, ^usually a ^{3.0g / cm 3 ~3.4g / cm 3} , from the viewpoint of compatibility of flexibility and thermal conductivity, 3.0 g / ^cm 3 ~ it is preferably 3.3 g / cm ^3, more preferably ^{3.1g / cm 3 ~3.3g / cm 3} . The density of a resin composition layer can be adjusted with the compounding quantity of an inorganic filler, for example.

  In the present disclosure, the density of the resin composition layer refers to an average value of the densities of all the resin composition layers when the resin composition layer has two or more resin composition layers. Moreover, when the release film is contained in the resin sheet, it means the density of the resin composition layer excluding the release film.

  The resin sheet has a first resin composition layer containing an epoxy resin composition and a second resin composition layer containing an epoxy resin composition laminated on the first resin composition layer. Is preferred. For example, the resin sheet is preferably a laminate of a first resin composition layer formed from an epoxy resin composition and a second resin composition layer formed from an epoxy resin composition. Thereby, the withstand voltage can be further improved. The epoxy resin compositions forming the first resin composition layer and the second resin composition layer may have the same composition or different compositions. From the viewpoint of thermal conductivity, it is preferable that the epoxy resin composition forming the first resin composition layer and the second resin composition layer have the same composition.

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

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

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

  The thickness of the resin sheet can be appropriately selected according to the purpose. The thickness of the resin composition layer can be set to, for example, 50 μm to 350 μm, and is preferably 60 μm to 300 μm from the viewpoint of thermal conductivity, insulation, and sheet flexibility.

<B stage sheet>
The B stage sheet of the present disclosure has a semi-cured resin composition layer including a semi-cured product of the epoxy resin composition of the present disclosure. The B-stage sheet can be produced, for example, by a production method including a step of heat-treating the resin composition layer in the resin sheet of the present disclosure to the B-stage state. Since the B stage sheet of the present disclosure is formed by the epoxy resin composition of the present disclosure, the B stage sheet is excellent in thermal conductivity, insulation, and sheet flexibility.

  From the viewpoint of handleability, it is preferable that the resin composition layer, which is the A stage of the resin sheet, is made into a B stage to form a B stage sheet.

  The heat treatment conditions for converting the A-stage resin composition layer to the B-stage are not particularly limited as long as the resin composition layer can be semi-cured to the B-stage state, and is appropriately selected according to the configuration of the epoxy resin composition. can do. For the purpose of eliminating voids in the resin composition layer generated when the epoxy resin composition is applied, it is preferable to apply a heat treatment method selected from hot vacuum press, hot roll laminating and the like. Thereby, a flat B stage sheet | seat can be manufactured efficiently. Specifically, for example, the resin composition layer can be semi-cured in a B-stage state by performing heat and pressure treatment at 80 ° C. to 180 ° C. for 1 second to 3 minutes under reduced pressure (for example, 1 kPa). Moreover, the pressure of pressurization can be 5 MPa-20 MPa.

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

<C stage sheet>
The C stage sheet of the present disclosure has a cured resin composition layer including a cured product of the epoxy resin composition of the present disclosure. The C stage sheet can be manufactured by a manufacturing method including a step of heat-treating a resin sheet or a B stage sheet to a C stage state, for example. The conditions for heat-treating the resin sheet or the B-stage sheet are not particularly limited as long as the resin composition layer or the semi-cured resin composition layer can be cured to the C-stage state, and are appropriately selected according to the configuration of the epoxy resin composition. can do. From the viewpoint of suppressing the generation of voids in the C stage sheet and improving the heat resistance of the C stage sheet, it is preferable to apply a heat treatment method such as a hot vacuum press. Thereby, a flat C stage sheet can be manufactured efficiently. Specifically, for example, the resin composition layer or the semi-cured resin composition layer can be cured in a C-stage state by heating and pressing at 150 to 250 ° C. for 1 to 60 minutes and 1 to 30 MPa. it can.

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

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

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

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

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

Examples of the metal foil include gold foil, copper foil, and aluminum foil, and copper foil is generally used.
The thickness of the metal foil is not particularly limited, and may be 1 μm to 50 μm, for example. In addition, it exists in the tendency which the flexibility of metal foil with a resin improves more by using metal foil of 20 micrometers or less.
As the metal foil, nickel, nickel-phosphorus alloy, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as an intermediate layer, and a copper layer of 0.5 μm to 15 μm is provided on one surface of the intermediate layer A composite foil having a three-layer structure in which a copper layer of 10 μm to 300 μm is provided on the other surface of the intermediate layer or a composite foil having a two-layer structure in which an aluminum foil and a copper foil are combined can also be used.

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

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

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

  The material and thickness of the metal support and metal plate are appropriately selected according to the purpose. Specifically, a metal such as copper, aluminum, or iron can be used, and the thickness can be set to 0.3 mm to 5 mm.

The metal substrate of this indication can be manufactured as follows, for example.
A resin composition layer is formed by applying and drying an epoxy resin composition on a metal support such as aluminum as in the case of a metal foil with a resin and the like, and a metal plate is disposed on the resin composition layer. And a metal substrate can be manufactured by heat-pressing this and hardening | curing a resin composition layer. In addition, a metal foil with a resin is laminated on a metal support so that the semi-cured resin composition layer faces the metal support, and then this is heated and pressurized to cure the semi-cured resin composition layer. It can also be manufactured.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
The material used for preparation of an epoxy resin composition and its abbreviation are shown below.

(Epoxy resin)
Resin A [4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate, epoxy equivalent: 212 g / eq, described in JP 2011-74366 A Manufactured by the method]

・ Resin B
A part of the resin A represented by the above structure was reacted with a predetermined amount of hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd., hydroxyl equivalent: 55 g / eq), and a prepolymerized compound was used as the resin B.
The ratio (Ep / Ph) between the number of equivalents of epoxy groups (Ep) of resin A and the number of equivalents of phenolic hydroxyl groups derived from hydroquinone (Ph) was 100/13.

<Synthesis of Resin B (Prepolymerization)>
50 g (0.118 mol) of Resin A was weighed into a 500 mL three-necked flask, and 80 g of propylene glycol monomethyl ether was added thereto. A cooling tube and a nitrogen introducing tube were installed in the three-necked flask, and a stirring blade was attached so as to be immersed in the solvent. This three-necked flask was immersed in a 120 ° C. oil bath, and stirring was started. After confirming that the resin A was dissolved and became a transparent solution, hydroquinone was added so that Ep / Ph was 100/13, 0.5 g of triphenylphosphine was further added, and an oil bath at 120 ° C. Heating was continued at temperature. After continuing the heating for 5 hours, propylene glycol monomethyl ether was distilled off under reduced pressure from the reaction solution, and the residue was cooled to room temperature (25 ° C.) to obtain a resin B in which a part of the resin A was prepolymerized. .

  The molecular weight of the structure estimated to be obtained from the reaction between resin A and hydroquinone is collated with the molecular weight of the target compound determined by liquid chromatography performed using a liquid chromatograph equipped with UV and mass spectrum detectors. Thus, it was confirmed that resin B contained at least one of the compounds having the following structure (dimer compound).

  Specifically, the liquid chromatography was performed using “LaChrom II C18” manufactured by Hitachi, Ltd. as the analytical column, tetrahydrofuran as the eluent, and a flow rate of 1.0 ml / min. When the absorbance at a wavelength of 280 nm was detected with a UV spectrum detector, a compound having the following structure had a peak at a position of 17.4 minutes, and resin A had a peak at a position of 14.9 minutes. Moreover, when it detected with the ionization voltage of 2700V in the mass spectrum detector, all the molecular weights of the compound of the following structure were 959 in the state to which one proton was added.

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

  The epoxy equivalent of resin B was measured by the perchloric acid titration method.

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

Resin C [mixture of liquid bisphenol A type epoxy resin and bisphenol F type epoxy resin, “ZX-1059” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent of 165 g / eq]
Resin D [Triphenylmethane type epoxy compound, “EPPN-502H” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent of 168 g / eq]

(Filler)
AA-3 [alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 3 μm]
AA-04 [Alumina particles, manufactured by Sumitomo Chemical Co., Ltd., D50: 0.40 μm]
-HP-40 [boron nitride particles, manufactured by Mizushima Alloy Iron Co., Ltd., D50: 40 μm, scaly aggregate, aspect ratio: 1.5, crystal form: hexagonal crystal]

(Curing agent)
DDS [4,4′-diaminodiphenylsulfone, manufactured by Wako Pure Chemical Industries, Ltd.]
DDM-Et [3,3′-diethyl-4,4′-diaminodiphenylmethane, “KAYAHARD A-A” manufactured by Nippon Kayaku Co., Ltd.]
CRN [catechol resorcinol novolak resin (mass-based charge ratio: catechol / resorcinol = 5/95), containing 50% by mass of cyclohexanone]

<Synthesis method of CRN>
To a 3 L separable flask equipped with a stirrer, a condenser and a thermometer, 627 g of resorcinol, 33 g of catechol, 316.2 g of a 37 mass% formaldehyde aqueous solution, 15 g of oxalic acid and 300 g of water were added, and the mixture was heated while heating in an oil bath. The temperature was raised to ° C. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system to obtain a catechol resorcinol novolak resin CRN.

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

(Additive)
KBM-403: 3-glycidoxypropyltriethoxysilane [silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd., trade name]
· KBM-573: 3-phenylaminopropyltrimethoxysilane [silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd., trade name]

(solvent)
CHN: cyclohexanone

(Support)
PET film [Teijin Film Solutions Co., Ltd. “A53”, thickness 50 μm]
Copper foil [Furukawa Electric Co., Ltd. “GTS grade”, thickness: 105 μm]
Copper foil [Fukuda Metal Foil & Powder Co., Ltd. “CF-T9D-SV”, thickness: 35 μm]

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

<Production of A stage sheet>
The varnish-like epoxy resin composition was applied onto a PET film using an applicator and then dried in a box-type oven at 130 ° C. for 5 minutes to obtain an A stage sheet (resin sheet) having a thickness of 120 μm.

<Preparation of B stage sheet>
The coated surfaces of the above-mentioned A stage sheets are bonded together, and under the conditions for producing the B stage sheet shown in Table 2, hot pressing is performed with a vacuum press, and B with a PET film sandwiched between two PET films A stage sheet was obtained. Of the B stage sheet with a PET film, the thickness excluding the PET film was 150 μm.

<Preparation of a sample for measuring glass transition temperature and thermal conductivity>
The PET film was peeled off from both surfaces of the above B-stage sheet with PET film to obtain a B-stage sheet. Two B stage sheets were stacked, and a 105 μm thick copper foil was disposed on both sides thereof. At this time, it arrange | positioned so that the roughening surface of copper foil might contact a B stage sheet | seat. And the vacuum thermocompression bonding was performed with the vacuum press on the preparation conditions of the hardened | cured material of Table 2, and the epoxy resin hardened | cured material 1 with copper foil was obtained.
Then, the copper foil of both surfaces of the epoxy resin hardened | cured material 1 with copper foil was removed by etching using the sodium persulfate solution, and the epoxy resin hardened | cured material 1 (C stage sheet) was obtained. Glass transition temperature and thermal conductivity were measured using the obtained C stage sheet.

<Preparation of peel strength measurement sample>
The PET film was peeled off from both sides of the above B-stage sheet with PET film to obtain a B-stage sheet, and then a 35 μm thick copper foil was placed on both sides. At this time, it arrange | positioned so that the roughening surface of copper foil might contact a B stage sheet | seat. And the vacuum thermocompression bonding was performed with the vacuum press on the preparation conditions of the hardened | cured material of Table 2, and the epoxy resin hardened | cured material 2 with copper foil was obtained. The peel strength was measured using the obtained epoxy resin cured product 2 with copper foil.

<Preparation of samples for evaluation of adhesion and insulation>
After the PET film was peeled off from both sides of the B stage sheet with the PET film to obtain a B stage sheet, a 0.5 mm thick copper plate was placed on one side, and a 2 mm thick copper plate was placed on the other side. At this time, it arrange | positioned so that the roughening surface of each copper plate might contact a B stage sheet | seat. And the vacuum thermocompression bonding was performed with the vacuum press on the preparation conditions of the hardened | cured material of Table 2, and the epoxy resin hardened | cured material with a copper plate was obtained. Using the obtained epoxy resin cured product with a copper plate, the insulating properties and the adhesion of the cured epoxy resin product to the copper plate were evaluated.

<Evaluation>
(Evaluation of flexibility)
When the A stage sheet was wound around a cylinder having a diameter of 40 mm, it was confirmed whether or not cracking occurred.
-Flexibility evaluation criteria-
A: No cracking and flexibility B: Cracking and no flexibility

(Measurement of glass transition temperature)
The C stage sheet obtained above was cut into 30 mm × 5 mm and used as a sample. The sample was placed in a dynamic viscoelasticity measuring apparatus (“E-4000” manufactured by UBM Co., Ltd.) using a tensile vibration test jig, and the frequency was 10 Hz, the heating rate was 5 ° C./min, and 30 ° C. The dynamic viscoelasticity was measured in a temperature range of ˜330 ° C. to determine the glass transition temperature.

<Measurement of thermal conductivity>
The C stage sheet obtained above was cut into a 10 mm square and used as a sample. After the sample was blackened with graphite spray, the thermal diffusivity was measured by a xenon flash method (NETZSCH-Geratebau GmbH, “LFA447 nanoflash” manufactured by Selb / Bayer). From the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (“DSC Pyris 1” manufactured by Perkin Elmer, Inc.), the thermal conductivity in the thickness direction of the C stage sheet was determined.
Thermal conductivity λ (W / (m · K)) = α × ρ × Cp
α: Thermal diffusivity (m ² / s)
ρ: Density (kg / cm ³ )
Cp: Specific heat (capacity) (kJ / (kg · K))

<Measurement of peel strength>
The epoxy resin cured product 2 with copper foil obtained above was cut into 2.5 cm × 10 cm. And the copper foil of one side was cut off with the cutter so that it might leave with the dimension of 1 cm x 10 cm in the center part, the surrounding part was peeled off, and this was made into the sample. Using “Autograph AG-X” manufactured by Shimadzu Corporation, install a load cell of 100N, and with a special jig, pick the copper foil at a position 2 cm from the end of the long side of the 1 cm × 10 cm copper foil in the sample. The peel strength with respect to the copper foil was measured at a pulling speed of 50 mm / min and a measurement temperature of room temperature (25 ° C.), 190 ° C., 230 ° C., and 275 ° C.

<Evaluation of adhesion and insulation before and after high temperature treatment>
Using the epoxy resin cured product with a copper plate obtained above, peeling of the cured epoxy resin product with respect to the copper plate was observed by an ultrasonic flaw detection method using “INSIGHT-300” manufactured by Insight Co., Ltd. A 35 MHz probe was used for observation. This was evaluated as adhesiveness before high temperature treatment.
After evaluating the adhesiveness, the 2 mm thick copper plate of the epoxy resin cured product with a copper plate is left on the entire surface, and the other 0.5 mm thick copper plate is left in a circular pattern with a diameter of 20 mm. It removed by etching with the sodium persulfate solution, and the sheet-like epoxy resin hardened material with an electrode (epoxy resin hardened | cured material with an electrode) was obtained. Using a dielectric breakdown test apparatus (insulating material test system manufactured by Soken Denki Co., Ltd.), the electrode is sandwiched between 10 mm diameter cylindrical electrodes so as to be in contact with the circular pattern of the copper plate of the epoxy resin cured product with electrodes, and the pressure increase rate is 500 V / s, AC 60 Hz. The dielectric breakdown voltage was measured in a cutoff current of 10 mA, 25 ° C. in Fluorinert. This was evaluated as insulation before high temperature treatment.
Subsequently, the cured epoxy resin product with an electrode whose dielectric breakdown voltage was measured was placed on a hot plate heated to 320 ° C., and was further placed for 5 minutes after the temperature of the cured epoxy resin product with an electrode reached 285 ° C. Thereafter, the dielectric breakdown voltage of the cured epoxy resin with electrode was measured in the same manner as described above. This was evaluated as insulation after high-temperature treatment.
Thereafter, in the same manner as described above, peeling was observed by an ultrasonic flaw detection method. This was evaluated as adhesiveness after high temperature treatment.

-Adhesion evaluation criteria-
A: Generation of peeling is less than 10 area% in one sample B: Generation of peeling exceeds 10 area% in one sample

  Table 2 shows the composition and production conditions of each epoxy resin composition, and the evaluation results of adhesion and insulation pressure.

  Table 3 shows the compositions and production conditions of the epoxy resin compositions of Example 3, Example 4, Comparative Example 2 and Comparative Example 3, and the measurement results of peel strength.

  As shown in Table 2, an epoxy resin containing a dimer compound, an amine-based curing agent, and a filler containing a nitride filler are contained, and the nitride filler content is 42% by volume to 75% by volume. In Examples 1 to 6, A stage sheets excellent in flexibility were obtained. When the A stage is inferior in flexibility, the B stage is also inferior in flexibility. Moreover, it turned out that hardened | cured material is excellent in heat conductivity, heat resistance, the adhesiveness before and behind high temperature processing, and insulation.

  In Comparative Example 1 in which the content of the nitride filler was less than 42% by volume, the thermal conductivity was remarkably low, so the glass transition temperature, the adhesiveness before and after the high temperature treatment, and the insulation were not evaluated.

  Example 3, Example 4, and Comparative Example 2 all use the same epoxy resin, and the type and content of the filler are the same. However, it can be seen that Example 3 and Example 4 cured with an amine curing agent have a higher glass transition temperature and superior heat resistance than Comparative Example 2 cured with a phenol curing agent.

  In addition, as shown in Tables 2 and 3, the adhesiveness and insulating properties before and after the high temperature treatment, and the peel strength with respect to the metal foil are superior to those of Comparative Example 2 in Example 3 and Example 4. Recognize.

  Comparative Example 3 uses an amine-based curing agent, but is inferior in adhesion and insulation after high-temperature treatment. Therefore, it can be seen that not only the amine-based curing agent but also the epoxy resin having a mesogenic skeleton is used in combination with the thermal conductivity, heat resistance, adhesiveness before and after high temperature treatment, and insulation.

  In Example 3 and Example 4, the adhesiveness and insulating properties before and after the high temperature treatment when the press pressure in the cured product was reduced to 10 MPa were evaluated, and together with the evaluation results in the case of 15 MPa, Table 4 Show.

  Example 3 and Example 4 have the same composition except that the type of amine curing agent is different. However, it can be seen that by using DDM-Et together as in Example 4, the adhesiveness and heat resistance before and after the high temperature treatment are excellent even when the press pressure is lowered.

Claims (17)

An epoxy resin, an amine curing agent, and a filler are contained, the filler includes a nitride filler, and the epoxy resin has two structural units represented by the following general formula (I) in one molecule. An epoxy resin composition comprising a monomer compound, wherein the content of the nitride filler is 42% by volume to 75% by volume.

[In General Formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently. ]   The epoxy resin composition of Claim 1 whose ratio of the dimer compound to the said epoxy resin is 15 mass%-28 mass%. The dimer compound has at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB). Or the epoxy resin composition of Claim 2.

[In General Formula (IA) and General Formula (IB), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents 1 to 8 carbon atoms. Represents an alkyl group. n shows the integer of 0-4. ] The structural unit represented by the general formula (IA) is selected from the group consisting of a structural unit represented by the following general formula (IA-1) and a structural unit represented by the following general formula (IA-2). The epoxy resin composition according to claim 3, comprising at least one structural unit.

[In General Formula (IA-1) and General Formula (IA-2), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ] The structural unit represented by the general formula (IB) is selected from the group consisting of a structural unit represented by the following general formula (IB-1) and a structural unit represented by the following general formula (IB-2). The epoxy resin composition according to claim 3 or 4, comprising at least one structural unit.

[In General Formula (IB-1) and General Formula (IB-2), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ] The dimer compound comprises a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and a compound represented by the following general formula (II-C). The epoxy resin composition according to any one of claims 1 to 5, comprising at least one compound selected from the group.


[In General Formula (II-A) to General Formula (II-C), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently represents carbon. The alkyl group of number 1-8 is shown. n shows the integer of 0-4. ] The dimer compound is a compound represented by the following general formula (II-A-1), a compound represented by the following general formula (II-B-1), and the following general formula (II-C-1). The epoxy resin composition according to any one of claims 1 to 6, comprising at least one compound selected from the group consisting of the represented compounds.

[In General Formula (II-A-1) to General Formula (II-C-1), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ represents Independently, an alkyl group having 1 to 8 carbon atoms is shown. n shows the integer of 0-4. ] The said epoxy resin is an epoxy resin composition of any one of Claims 1-7 containing the epoxy compound represented by the following general formula (III).


[In General Formula (III), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently. ]   The epoxy resin composition of Claim 8 whose ratio of the epoxy compound represented by the said general formula (III) to the said epoxy resin is 57 mass%-80 mass%.   The epoxy resin composition according to any one of claims 1 to 9, wherein a content of the filler is 50% by volume to 90% by volume.   The epoxy resin composition according to any one of claims 1 to 10, wherein the amine-based curing agent includes at least one selected from the group consisting of amine-based curing agents having a benzene ring or a naphthalene ring. .   The resin sheet which has a resin composition layer containing the epoxy resin composition of any one of Claims 1-11.   The B stage sheet which has a semi-hardened resin composition layer containing the semi-hardened material of the epoxy resin composition of any one of Claims 1-11.   The C stage sheet which has a cured resin composition layer containing the hardened | cured material of the epoxy resin composition of any one of Claims 1-11.   The hardened | cured material of the epoxy resin composition of any one of Claims 1-11.   The metal with a resin provided with metal foil and the semi-hardened resin composition layer containing the semi-hardened material of the epoxy resin composition of any one of Claims 1-11 arrange | positioned on the said metal foil. Foil.   A cured resin composition layer comprising a metal support, a cured product of the epoxy resin composition according to any one of claims 1 to 11 disposed on the metal support, and the cured resin composition. A metal substrate comprising: a metal plate disposed on the layer.