Sheet for forming a thermally conductive layer, and method for producing the sheet for forming a thermally conductive layer

Abstract

The present invention also addresses the problem of providing a thermally conductive layer-forming sheet, with a thermally conductive layer formed therefrom exhibiting excellent adhesive properties and thermal conductivity. The present invention also addresses the problem of providing a method for producing the thermally conductive layer-forming sheet.　This thermally conductive layer-forming sheet includes: a film formed using a composition containing an inorganic material and a thermosetting compound; and an adhesive layer disposed on at least a part of a surface of the film. The film satisfies requirement 1 and the adhesive layer satisfies requirement 2. Requirement 1: if the arithmetic mean roughness Ra of the adhesive layer side surface of the film is denoted by A (μm), the relationship of formula (1) is satisfied.　Formula (1): 5.0 ≤ A ≤ 15.0 Requirement 2: if the coverage ratio of the adhesive layer on the surface of the film on which the adhesive layer is disposed is denoted by B (%), the relationship of formula (2) is satisfied.　Formula (2): 40.0+A ≤ B ≤ 80.0+A

Description

[Technical Field]

[0001] The present invention relates to a sheet for forming a thermally conductive layer and a method for producing the sheet for forming a thermally conductive layer. [Background technology]

[0002] Power semiconductor devices used in various electrical appliances such as personal computers, general home appliances, and automobiles have been rapidly becoming smaller in size in recent years. As the size of these devices has increased, it has become more difficult to control the heat generated by these devices. To address this problem, a method has been used in which a heat-conducting layer with excellent thermal conductivity is bonded to the device components to promote heat transfer and heat dissipation. For example, Patent Document 1 discloses a film with excellent adhesiveness and high thermal conductivity, which is "a thermosetting adhesive film (claim 1) obtained by laminating a filler-free epoxy resin film having a melt viscosity of 2 Pa·s or less at 170°C to both sides of a filled film made of an epoxy resin containing 70 to 95% by weight of an inorganic filler, a rubber component, and a curing agent component." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-012834 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have studied the film described in Patent Document 1 and found that it is difficult to achieve both adhesiveness and thermal conductivity when the film is used as a thermally conductive layer.

[0005] Therefore, an object of the present invention is to provide a sheet for forming a thermal conductive layer that provides a thermal conductive layer having excellent adhesiveness and thermal conductivity, and also to provide a method for producing the sheet for forming a thermal conductive layer. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[0007] [1] a film formed using a composition containing an inorganic substance and a thermosetting compound; An adhesive layer disposed on a portion of the surface of the film, The film satisfies the following requirement 1, The sheet for forming a thermally conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A [2] The sheet for forming a thermally conductive layer according to [1], wherein the above A is 7.0 to 13.0. [3] The sheet for forming a thermally conductive layer according to [1] or [2], wherein the inorganic material includes aggregated boron nitride. [4] The sheet for forming a thermally conductive layer according to [3], wherein the aggregated boron nitride has an average particle size of 20 μm or more. [5] The sheet for forming a thermally conductive layer according to any one of [1] to [4], wherein the thermosetting compound includes an epoxy compound. [6] The sheet for forming a thermal conductive layer according to [5], wherein the thermosetting compound includes a phenol compound. [7] a film forming step of forming a film using a composition containing an inorganic substance and a thermosetting compound; An adhesive layer forming step of disposing an adhesive layer on a part of the surface of the film, The film satisfies the following requirement 1, The method for producing a sheet for forming a thermal conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A [8] In the adhesive layer forming step, [7] The method for producing a sheet for forming a thermal conductive layer according to [7], wherein an adhesive is applied directly to the surface of the film, and the adhesive layer is disposed on the surface of the film. [9] In the adhesive layer forming step, An adhesive is applied to the surface of the release sheet to form an adhesive transfer layer, The method for producing a sheet for forming a thermal conductive layer according to [7], wherein the adhesive transfer layer formed on the surface of the release sheet is transferred to the surface of the film, and the adhesive layer is disposed on the surface of the film.

[10] an adhesive layer forming step of applying an adhesive to a release sheet to form an adhesive layer; a film forming step of forming a film on the surface of the release sheet on which the adhesive layer is formed, using a composition containing an inorganic substance and a thermosetting compound, The film satisfies the following requirement 1, The method for producing a sheet for forming a thermal conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A

[11]

[11] The method for producing a sheet for forming a thermal conductive layer according to any one of [8] to

[10] , wherein the application of the adhesive is carried out by any one of spray application, screen printing, gravure printing, and inkjet printing. [Effects of the Invention]

[0008] The present invention can provide a sheet for forming a thermally conductive layer, which provides a thermally conductive layer having excellent adhesiveness and thermal conductivity, and also provides a method for producing the sheet for forming a thermally conductive layer. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a conceptual diagram showing a cross section of one embodiment of a conventional sheet for forming a thermally conductive layer. [Figure 2] FIG. 2 is a conceptual diagram showing a cross section of an embodiment of a conventional sheet for forming a thermally conductive layer when it is attached to an adherend. [Figure 3] 1 is a conceptual diagram showing a cross section of one embodiment of a sheet for forming a thermally conductive layer of the present invention. [Figure 4] 1 is a conceptual diagram of one embodiment of a sheet for forming a thermally conductive layer of the present invention. [Figure 5] 1 is a conceptual diagram showing a cross section of an embodiment of a sheet for forming a thermally conductive layer of the present invention when it is attached to an adherend. DETAILED DESCRIPTION OF THE INVENTION

[0010] The sheet for forming a thermally conductive layer of the present invention and the method for producing the sheet for forming a thermally conductive layer will be described in detail below. The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0011] In this specification, when referring to the values ​​of parameters that may vary with temperature, the values ​​are those at 25°C unless otherwise specified.

[0012] In this specification, the term "(meth)acryloyl group" means "either one or both of an acryloyl group and a methacryloyl group," and the term "(meth)acrylamide group" means "either one or both of an acrylamide group and a methacrylamide group."

[0013] In this specification, the acid anhydride group may be a monovalent group or a divalent group. When the acid anhydride group represents a monovalent group, examples thereof include substituents obtained by removing any hydrogen atom from acid anhydrides such as maleic anhydride, phthalic anhydride, pyromellitic anhydride, and trimellitic anhydride. When the acid anhydride group represents a divalent group, a group represented by *-CO-O-CO-* is intended (* represents the bonding position).

[0014] In this specification, a substituent or the like that is not specified as substituted or unsubstituted may, if possible, further have a substituent (for example, a group of substituents Y described below) within a range that does not impair the intended effect. For example, the expression "alkyl group" means a substituted or unsubstituted alkyl group (an alkyl group that may have a substituent) within a range that does not impair the intended effect. In addition, in the present specification, when it is stated that a compound "may have a substituent," the type, position, and number of the substituent are not particularly limited. The number of the substituents may be, for example, one or two or more. Examples of the substituent include monovalent nonmetallic atomic groups excluding hydrogen atoms, and groups selected from the following substituent group Y are preferred. In this specification, examples of halogen atoms include chlorine atoms, fluorine atoms, bromine atoms, and iodine atoms.

[0015] Permutation group Y: Halogen atoms (-F, -Br, -Cl, -I, etc.), hydroxyl groups, amino groups, carboxylic acid groups and their conjugate base groups, carboxylic anhydride groups, cyanate ester groups, unsaturated polymerizable groups, epoxy groups, oxetanyl groups, aziridinyl groups, thiol groups, isocyanate groups, thioisocyanate groups, aldehyde groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, N-alkylamino groups, N,N-dialkylamino groups, N-arylamino groups, N,N-diarylamino groups, N-alkyl-N-arylamino groups, an acyloxy group, a carbamoyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an N,N-dialkylcarbamoyloxy group, an N,N-diarylcarbamoyloxy group, an N-alkyl-N-arylcarbamoyloxy group, an alkylsulfoxy group, an arylsulfoxy group, an acylthio group, an acylamino group, an N-alkylacylamino group, an N-arylacylamino group, a ureido group, an N'-alkylureido group, an N',N'-dialkylureido group, an N'-arylureido group, or an N',N'-diarylureido group; N'-Alkyl-N'-arylureido group, N-alkylureido group, N-arylureido group, N'-alkyl-N-alkylureido group, N'-alkyl-N-arylureido group, N',N'-dialkyl-N-alkylureido group, N',N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N'-aryl-N-arylureido group, N',N'-diaryl-N-alkylureido group, N',N'-diaryl-N-arylureido group, N'-alkyl-N'-aryl-N-alkylureido group , N'-alkyl-N'-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N,N-dialkylcarbamoyl group, N-arylcarbamoyl group, N,N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (-SO3H) and its conjugate base group, alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N,N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N,N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N,N-dialkylsulfamoyl group, N-arylsulfamoyl group, N,N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, N-acylsulfamoyl group and its conjugate base group, N-alkylsulfonylsulfamoyl group (-SONHSO(alkyl)) and its conjugate base group, N-arylsulfonylsulfamoyl group (-SONHSO(aryl)) and its conjugate base group, N-alkylsulfonylcarbamoyl group (-CONHSO(alkyl)) and its conjugate base group, N-arylsulfonylcarbamoyl group (-CONHSO(aryl)) and its conjugate base group, alkoxysilyl group (-Si(Oalkyl)3), aryloxysilyl group (-Si(Oaryl)3), hydroxysilyl group (-Si(OH)3) and its conjugate base group, phosphono group (-PO3H2) and its conjugate base group, dialkylphosphono group (-PO3(alkyl)) 2), diarylphosphono group (-PO3(aryl)2), alkylarylphosphono group (-PO3(alkyl)(aryl)), monoalkylphosphono group (-PO3H(alkyl)) and its conjugate base group, monoarylphosphono group (-PO3H(aryl)) and its conjugate base group, phosphonooxy group (-OPO3H2) and its conjugate base group, dialkylphosphonooxy group (-OPO3(alkyl)2), diarylphosphonooxy group (-OPO3(aryl)2), alkylarylphosphonooxy group (-OPO3(alkyl)(aryl)), monoalkylphosphonooxy group (-OPO3H(alkyl)) and its conjugate base group, monoarylphosphonooxy group (-OPO3H(aryl)) and its conjugate base group, cyano group, nitro group, aryl group, alkenyl group, alkynyl group, and alkyl group. Furthermore, each of the above groups may have further substituents (e.g., one or more of the above groups) if possible. For example, an aryl group which may have a substituent is also included as a group which can be selected from the substituent group Y. When the group selected from the substituent group Y has a carbon atom, the group has 1 to 20 carbon atoms, for example. The number of atoms other than hydrogen atoms contained in the group selected from the substituent group Y is 1 to 30, for example. Furthermore, these substituents may or may not bond to each other or to the group they substitute, if possible, to form a ring. For example, an alkyl group (or an alkyl group portion in a group containing an alkyl group as a partial structure, such as an alkoxy group) may be a cyclic alkyl group (cycloalkyl group) or an alkyl group having one or more cyclic structures as a partial structure.

[0016] [Thermal conductive layer forming sheet] The sheet for forming a thermally conductive layer of the present invention is a sheet for forming a thermally conductive layer, which has a film formed using a composition containing an inorganic substance and a thermosetting compound, and an adhesive layer arranged on a portion of the surface of the film. Furthermore, the film satisfies the following requirement 1, and the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A

[0017] The mechanism by which the problem of the present invention is solved by the above-described configuration of the sheet for forming a thermally conductive layer is not entirely clear, but the present inventors speculate as follows. The sheet for forming a thermal conductive layer of the present invention will be described below with reference to the drawings. For the sake of convenience, the scale of each component in the drawings and the coverage of the adhesive layer in the sheet for forming a thermal conductive layer of the present invention may differ from the actual scale. Although films made of compositions containing inorganic substances and thermosetting compounds have good thermal conductivity, particularly due to the presence of the inorganic substances, the inorganic substances often hinder the adhesiveness of the thermally conductive layer. Therefore, the present inventors have found that while the adhesiveness of the thermally conductive layer can be improved by providing an adhesive layer on the surface of the film, the adhesive layer itself often hinders the thermal conductivity of the thermally conductive layer. More specifically, as shown in FIG. 1, when an attempt is made to attach a thermally conductive layer-forming sheet 140 having an adhesive layer 120 disposed over the entire surface of one surface of a film 100 to a specified adherend via the adhesive layer, the adhesive layer 120 exists between the film 100 and the adherend 160 as shown in FIG. 2, and therefore the thermal conductivity between the adherend 160 and the film 100 is inhibited. In contrast, in the thermal conductive layer-forming sheet of the present invention, the arithmetic mean roughness Ra of the film is adjusted to fall within a predetermined range, and the coverage of the adhesive layer on the film is adjusted to fall within a predetermined range. Figures 3 and 4 show conceptual diagrams of one embodiment of the thermal conductive layer-forming sheet of the present invention. Figure 3 is a cross-sectional view of one embodiment of the thermal conductive layer-forming sheet of the present invention, and Figure 4 is a plan view of one embodiment of the thermal conductive layer-forming sheet of Figure 3. Note that Figure 3 corresponds to a cross-sectional view taken along line AA in Figure 4. The thermal conductive layer-forming sheet 10 shown in Figures 3 and 4 has a film 12 formed using a film-forming composition described below and an adhesive layer 14 disposed on a portion of the surface of the film 12. The adhesive layer 14 is arranged in a pattern, and more specifically, is composed of a plurality of adhesive portions 16 arranged at intervals. When the thermally conductive layer-forming sheet of the present invention having the above-described configuration is adhered to an adherend, the adhesive layer, arranged at a predetermined coverage, spreads due to the pressure between the thermally conductive layer-forming sheet and the adherend. As shown in FIG. 5, the convex portions of the surface of the film 12 are often directly adhered to the adherend 18, or, if they are adhered via an adhesive, the adhesive is often very thin. Furthermore, the concave portions of the surface of the film 12 tend to have more adhesive layer 14, and are often adhered via a relatively thick adhesive layer. Therefore, when the thermally conductive layer-forming sheet of the present invention is adhered to an adherend, a good balance of good thermal conductivity regions (where the film surface is directly adhered to the adherend, or, if they are adhered via an adhesive, the adhesive is very thin) and good adhesion regions (where they are adhered via a relatively thick adhesive layer) can be present at the interface with the adherend. The inventors speculate that this results in good thermal conductivity and adhesion of the resulting thermally conductive layer. Hereinafter, when the sheet for forming a thermally conductive layer of the present invention has better at least one of thermal conductivity and adhesiveness, it is also referred to as having better effects of the present invention.

[0018] First, requirements 1 and 2 that the sheet for forming a thermally conductive layer of the present invention must satisfy will be described in detail below.

[0019] The sheet for forming a thermally conductive layer of the present invention satisfies the following requirement 1. Requirement 1: When the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film is A μm, A satisfies the relationship of formula (1). Formula (1) 5.0≦A≦15.0 That is, the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film is 5.0 to 15.0 μm. In particular, it is preferable that the above A indicates a value of 7.0 to 13.0. In other words, the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film is preferably 7.0 to 13.0 μm. If the value of A is within the above range (i.e., the arithmetic mean roughness Ra of the film is within a predetermined value), it is easy to control the spread of the adhesive layer within an appropriate range when the thermally conductive layer-forming sheet is brought into contact with an object (adherend) to which heat is to be transferred. This is thought to ensure that when the thermally conductive layer-forming sheet is adhered to the adherend, there will be a good balance of good thermally conductive areas and good adhesive areas at the interface with the adherend. When an adhesive layer is disposed on one surface of the film (one of the two opposing main surfaces), the surface on which the adhesive layer is disposed only needs to satisfy Requirement 1 above. When adhesive layers are disposed on both surfaces of the film, it is sufficient that the above requirement 1 is satisfied on at least one surface side.

[0020] In this specification, the arithmetic mean roughness Ra of the film is usually determined by the following method: the film surface is observed at 100x magnification using a laser microscope "VK-9710" manufactured by Keyence Corporation, and measurement is performed based on JIS B0601 (2001) using an analytical application.

[0021] When the arithmetic mean roughness Ra of the surface of the film cannot be determined by the above-described method using a laser microscope due to the influence of the adhesive layer disposed on the surface of the film, the arithmetic mean roughness Ra may be determined by the method described below. That is, the cross section of the thermal conductive layer-forming sheet is observed with an SEM (scanning electron microscope). Then, in 10 randomly selected fields of view that include the surface side of the film on which the adhesive layer is formed, the uneven structure of the cross section of the part on the film where no adhesive layer is formed (part of only the film) is regarded as the surface shape of the film, and the arithmetic mean roughness Ra of the film is determined.

[0022] In addition, if the arithmetic mean roughness Ra of the film before the adhesive layer is disposed is known and it is recognized that the arithmetic mean roughness Ra of the surface of the film does not substantially change before and after the adhesive layer is disposed on the surface of the film, the arithmetic mean roughness Ra of the film before the adhesive layer is disposed may be treated as the arithmetic mean roughness Ra of the film in the sheet for forming a thermal conductive layer.

[0023] The adhesive layer satisfies the following requirement 2. Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A The value of B is a value (unit: %) indicating the ratio of the area covered by the adhesive layer to the surface of the film (coverage rate). For example, when the surface area Ra is 10.0 μm, the value of A is 10.0, and therefore, formula (2) is written as "50.0≦B≦90.0". The value of B depends on the value of A, but is within the range of 45.0 to 95.0, and preferably within the range of 55.0 to 80.0. Furthermore, in the sheet for forming a thermal conductive layer of the present invention, the relationship between the arithmetic mean roughness Ra (A μm) of the film and the coverage rate (B%) is preferably "40.0 + A ≦ B ≦ 80.0 + A" or "45.0 + A ≦ B ≦ 75.0 + A". Furthermore, it is preferable that "40.0≦BA≦80.0" and "45.0≦BA≦75.0".

[0024] The coverage (B%) of the thermal conductive layer-forming sheet of the present invention tends to increase in correlation with the arithmetic mean roughness Ra (A μm) of the film. This is because the greater the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film, the greater the amount of adhesive that flows into the recesses of the film when the thermal conductive layer-forming sheet is adhered to an adherend, and therefore a larger amount of adhesive is considered preferable.

[0025] 〔film〕 The sheet for forming a thermally conductive layer of the present invention has a film. The film is made of a composition (film-forming composition) containing an inorganic substance and a thermosetting compound. The film-forming composition and its components are described below.

[0026] The state of the film is preferably in the so-called A stage or B stage. In particular, the above film is preferably a film that can be cured from an A-stage or B-stage film to a C-stage film by further curing. In this specification, the A stage, B stage, and C stage refer to the definitions in JIS K6900:1994. In the A-stage, it is both soluble and fusible in certain solvents. In the B stage, the viscosity is 10 4 Pa·s~10 5 Pa·s at 100°C, whereas 2 Pa·s~10 3 A decrease in viscosity to Pa·s is preferred. Furthermore, in the C stage, it will not melt even when heated. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature rise rate 3° C. / min).

[0027] The average thickness of the film is preferably from 10 to 500 μm, more preferably from 50 to 300 μm, and even more preferably from 70 to 150 μm. The average film thickness is measured from a cross-sectional SEM image of the thermal conductive layer-forming sheet. More specifically, it is determined by averaging the thicknesses of adhesive-free areas in 10 randomly selected visual fields within the surface of the thermal conductive layer-forming sheet.

[0028] [Adhesive layer] The sheet for forming a thermally conductive layer of the present invention has an adhesive layer. The adhesive layer may be disposed on one side or on both sides of the film. The adhesive layer preferably satisfies a predetermined coverage rate and is disposed over substantially the entire surface of the film on which the adhesive layer is disposed.

[0029] The arrangement of the adhesive layer is not particularly limited and may be in a pattern such as a dotted, striped, lattice, tortoiseshell, random, or a combination thereof. There are no limitations on the shape of the dots in the dot-shaped adhesive layer, and examples thereof include a perfect circle, an ellipse, a triangle, a square, a polygon, and an irregular shape. For example, as shown in the above-described FIGS. 3 and 4 as examples, the adhesive layer may be made up of a plurality of adhesive portions arranged spaced apart from each other. When the adhesive layer is composed of a plurality of adhesive parts, the arrangement of the adhesive parts is not particularly limited as long as the relationship of the above-mentioned formula (2) is satisfied.

[0030] The size of the adhesive parts is not particularly limited, but for example, the average major axis of the dot-shaped adhesive parts is preferably 1 to 100 μm, more preferably 10 to 50 μm. When the adhesive layer is linear (for example, when the adhesive layer is striped, lattice, tortoiseshell, or randomly linear), the average line width of the adhesive layer is not particularly limited, and is, for example, preferably 1 to 100 μm, more preferably 10 to 50 μm. On the surface of the film on which the adhesive layer is disposed, portions (non-adhesion points) surrounded by the adhesive layer where the adhesive layer is not disposed may be spaced apart by the adhesive layer being in a lattice or tortoiseshell pattern, etc. The average major axis of the non-adhesion points is preferably 1 to 100 μm, more preferably 5 to 30 μm.

[0031] The average thickness of the adhesive layer (average height of the adhesive layer) is preferably from 0.5 to 40 μm, more preferably from 2 to 20 μm, and even more preferably from 3 to 12 μm. The average thickness of the adhesive layer is measured from a cross-sectional SEM image of the thermal conductive layer-forming sheet. More specifically, it is determined by averaging the thicknesses of the adhesive layer at the surface of the adhesive layer in 10 randomly selected visual fields on the cross section of the thermal conductive layer-forming sheet.

[0032] The coverage of the adhesive layer is determined from an SEM image of the thermal conductive layer-forming sheet. More specifically, the coverage is determined by averaging the percentage of the area where the adhesive is present on the surface of the film in 10 randomly selected fields of view within the surface of the thermal conductive layer-forming sheet observed with an SEM.

[0033] There is no limitation on the method for forming the adhesive layer, as long as the coverage by the adhesive layer is within a predetermined range. The method for forming the adhesive layer and the adhesive for forming the adhesive layer will be described later.

[0034] [Properties of the sheet for forming a thermally conductive layer] The thickness of the sheet for forming a thermal conductive layer of the present invention is preferably such that the average thickness of the thermal conductive layer formed using the sheet for forming a thermal conductive layer is 10 to 500 μm, more preferably 50 to 300 μm, and even more preferably 70 to 200 μm. The average thickness of the thermally conductive layer is measured with a micrometer.

[0035] For example, the specific average thickness of the sheet for forming a thermally conductive layer of the present invention is preferably 10 to 500 μm, more preferably 50 to 300 μm, and even more preferably 70 to 200 μm. The average thickness of the heat conductive layer-forming sheet is measured with a micrometer.

[0036] The heat conductive layer-forming sheet of the present invention may have a release sheet (such as a polyester film having a release surface) attached to a part or the entire surface of one or both sides of the heat conductive layer-forming sheet from the viewpoint of convenience of distribution, storage, and / or handling, etc. In this case, the release sheet is usually removed from the adhesive surface of the heat conductive layer-forming sheet before bonding the heat conductive layer-forming sheet to an adherend.

[0037] [Composition (film-forming composition)] The film in the sheet for forming a thermally conductive layer of the present invention is made of a predetermined composition (also referred to as a "film-forming composition"). The composition will now be described.

[0038] <Inorganic substances> The composition includes an inorganic material. As the inorganic substance, any inorganic substance that has been used as an inorganic filler in conventional thermally conductive materials may be used.

[0039] The shape of the inorganic material is not particularly limited and may be particulate, film-like, or plate-like. Examples of the shape of the particulate inorganic material include rice grain-like, spherical, cubic, spindle-like, scale-like, aggregated (a shape formed by aggregation of multiple primary particles), and irregular shapes.

[0040] Examples of inorganic oxides include silicon oxide (silica, SiO2), aluminum oxide (alumina, Al2O3), magnesium oxide (MgO), zirconium oxide (ZrO2), titanium oxide (TiO2), iron oxide (Fe2O3, FeO, Fe3O4), copper oxide (CuO, Cu2O), zinc oxide (ZnO), yttrium oxide (Y2O3), niobium oxide (Nb2O5), molybdenum oxide (MoO3), and indium oxide. Examples of oxides include tungsten oxide (WO3, W2O5), lead oxide (PbO, PbO2), bismuth oxide (Bi2O3), cerium oxide (CeO2, Ce2O3), antimony oxide (Sb2O3, Sb2O5), germanium oxide (GeO2, GeO), lanthanum oxide (La2O3), and ruthenium oxide (RuO2). The inorganic oxides may be used alone or in combination of two or more. The inorganic oxide may be an oxide that is produced when a metal prepared as a non-oxide is oxidized under environmental conditions.

[0041] Examples of inorganic nitrides include boron nitride (BN), carbon nitride (CN), silicon nitride (SiN), gallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN), chromium nitride (CrN), copper nitride (CuN), iron nitride (FeN), iron nitride (FeN), lanthanum nitride (LaN), lithium nitride (LiN), magnesium nitride (MgN), molybdenum nitride (MoN), niobium nitride (NbN), tantalum nitride (TaN), titanium nitride (TiN), tungsten nitride (WN), yttrium nitride (YN), and zirconium nitride (ZrN). The inorganic nitrides may be used alone or in combination of two or more. The inorganic nitride preferably comprises aluminum nitride or boron nitride, more preferably comprises boron nitride, and even more preferably comprises aggregated boron nitride.

[0042] The size of the inorganic substance is not particularly limited, but in terms of better dispersibility of the inorganic substance, the average particle size of the inorganic substance is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. The lower limit is not particularly limited, but in terms of handleability, it is preferably 10 nm or more, more preferably 100 nm or more. When using commercially available inorganic substances, the average particle size is determined by the catalog value. If no catalog value is available, the average particle size is determined by randomly selecting 100 inorganic substances using an electron microscope, measuring the particle size (major axis) of each inorganic substance, and then calculating the arithmetic average.

[0043] Among these, the inorganic substance preferably contains one or more selected from the group consisting of boron nitride, alumina, silica, silicon nitride, and magnesium oxide, more preferably contains boron nitride, and even more preferably contains aggregated boron nitride. The inorganic substance may contain the above-mentioned aggregated boron nitride as a part, or the inorganic substance may be the above-mentioned aggregated boron nitride itself. The content of the aggregated boron nitride is preferably 10 to 100 mass %, more preferably 40 to 100 mass %, and even more preferably 80 to 100 mass %, based on the total mass of the inorganic substance. The average particle size of the aggregated boron nitride is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. The lower limit of the average particle size is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

[0044] Only one type of inorganic substance may be used, or two or more types may be used. The inorganic material preferably contains at least one of an inorganic nitride and an inorganic oxide, more preferably contains at least an inorganic nitride, and may contain both an inorganic nitride and an inorganic oxide.

[0045] In order to obtain a thermally conductive material with superior thermal conductivity, the composition preferably contains at least an inorganic substance (preferably an inorganic nitride or inorganic oxide, more preferably an inorganic nitride, even more preferably boron nitride, and particularly preferably agglomerated boron nitride) having an average particle size of 20 μm or more (preferably 30 μm or more).

[0046] It is also preferable that the inorganic substance contained in the composition (preferably an inorganic nitride or inorganic oxide, more preferably an inorganic nitride, even more preferably boron nitride, and particularly preferably aggregated boron nitride) is essentially only inorganic substances having an average particle size of 20 μm or more (preferably 30 μm or more). "Substantially only inorganic substances having an average particle size of 20 μm or more" means that the content of inorganic substances having an average particle size of 20 μm or more exceeds 99 mass% relative to the total mass of the inorganic substances.

[0047] It is also preferable that the inorganic substances have different average particle sizes. For example, it is preferable to include both inorganic substance X, which is an inorganic substance with an average particle size of 20 μm or more, and inorganic substance Y, which is an inorganic substance with an average particle size of less than 20 μm. The inorganic substance X preferably has an average particle size of 20 to 300 μm, more preferably 30 to 200 μm. The inorganic substance Y preferably has an average particle size of 1 nm or more but less than 20 μm, more preferably 10 nm or more but 15 μm or less. The inorganic substance X is preferably an inorganic nitride or an inorganic oxide, more preferably an inorganic nitride, further preferably boron nitride, and particularly preferably aggregated boron nitride. The inorganic substance Y is preferably an inorganic nitride or an inorganic oxide, more preferably boron nitride or aluminum oxide. The inorganic substance X and the inorganic substance Y may each be used alone or in combination of two or more. The mass ratio of the content of inorganic substance X to the content of inorganic substance Y (content of inorganic substance X / content of inorganic substance Y) among the inorganic substances is preferably 50 / 50 to 99 / 1, more preferably 60 / 40 to 95 / 5.

[0048] The inorganic substance (particularly boron nitride) may be surface-treated. Note that the surface treatment refers to a treatment different from the surface modification using a surface modifier, which will be described later. By carrying out such treatment, functional groups are introduced onto the surface of the inorganic material, making it easier for the inorganic material to interact with curing agents (such as phenolic compounds), epoxy compounds, and / or the surface modifiers described below, and it is believed that the thermal conductivity and strength of the resulting thermal conductive material are further improved. Examples of surface treatments include plasma treatments (vacuum plasma treatment, atmospheric pressure plasma treatment, aqua plasma treatment, etc.), ultraviolet irradiation treatment, corona treatment, electron beam irradiation treatment, ozone treatment, baking treatment, flame treatment, oxidizing agent treatment, etc. The oxidizing agent treatment may be carried out under acidic conditions or basic conditions (e.g., pH 12 or higher).

[0049] The inorganic substance may also constitute a surface-modified inorganic substance (preferably a surface-modified inorganic nitride and / or a surface-modified inorganic oxide) in combination with a surface modifier. As used herein, "surface modification" refers to a state in which an organic substance is adsorbed onto at least a portion of the surface of an inorganic substance. The form of adsorption is not particularly limited, as long as it is a bonded state. That is, surface modification also includes a state in which an organic group obtained by partial detachment of the organic substance is bonded to the surface of the inorganic substance. The bond may be any bond, such as a covalent bond, a coordinate bond, an ionic bond, a hydrogen bond, a van der Waals bond, or a metallic bond. The surface modification may be performed so as to form a monolayer on at least a portion of the surface. A monolayer is a monolayer formed by chemical adsorption of organic molecules and is known as a self-assembled monolayer (SAM). Note that, as used herein, the surface modification may be performed on only a portion or the entire surface of the inorganic substance. As used herein, "surface-modified inorganic substance" refers to an inorganic substance that has been surface-modified with a surface modifier, i.e., a substance in which an organic substance is adsorbed onto the surface of the inorganic substance.

[0050] Examples of surface modifiers that can be used include carboxylic acids such as long-chain alkyl fatty acids, organic phosphonic acids, organic phosphate esters, and organic silane molecules (silane coupling agents). Other surface modifiers that can be used include those described in JP-A-2009-502529, JP-A-2001-192500, and Japanese Patent No. 4694929.

[0051] To obtain better effects of the present invention, the content of the inorganic substance in the composition is preferably 35% by volume or more, more preferably 50% by volume or more, and even more preferably 55% by volume or more, based on the total solid content of the composition. The upper limit of the content is less than 100% by volume, preferably 90% by volume or less, and more preferably 80% by volume or less. The inorganic substances may be used alone or in combination of two or more. The total solid content of the composition refers to the components that form the film, excluding the solvent. The film-forming components referred to here may be components whose chemical structure changes as a result of a reaction (polymerization) during film formation. Furthermore, any component that forms the film is considered to be a solid content even if it is in a liquid state.

[0052] <Thermosetting compounds> The composition includes a thermosetting compound. Hereinafter, a thermosetting compound is a compound that can be cured by heating, and may be a compound that can be cured by a single type alone. Also, even if a compound can be cured by the reaction of two or more compounds, when these two or more compounds coexist in a composition, each of these two or more compounds is referred to as a thermosetting compound.

[0053] Examples of the thermosetting compound include epoxy compounds, phenol compounds, oxetane compounds, melamine compounds, urea compounds, radical polymerizable compounds, and silicone compounds.

[0054] (epoxy compounds) In particular, the composition preferably contains at least an epoxy compound as the thermosetting compound. An epoxy compound is a compound having at least one epoxy group (oxiranyl group) in one molecule. The epoxy group is a group obtained by removing one or more hydrogen atoms (preferably one hydrogen atom) from an oxirane ring. If possible, the epoxy group may further have a substituent (such as a linear or branched alkyl group having 1 to 5 carbon atoms).

[0055] The number of epoxy groups that the epoxy compound has is preferably 2 or more, more preferably 2 to 40, still more preferably 2 to 10, and particularly preferably 2, in one molecule. The molecular weight of the epoxy compound is preferably 150 to 10,000, more preferably 150 to 1,000, and even more preferably 200 to 290.

[0056] The epoxy group content of the epoxy compound is preferably from 2.0 to 20.0 mmol / g, more preferably from 5.0 to 15.0 mmol / g, and even more preferably from 6.0 to 14.0 mmol / g. The epoxy group content refers to the number of epoxy groups contained in 1 g of the epoxy compound. The epoxy compound also preferably has an aromatic ring group (preferably an aromatic hydrocarbon ring group).

[0057] The epoxy compound may or may not exhibit liquid crystallinity. That is, the epoxy compound may be a liquid crystal compound, or in other words, a liquid crystal compound having an epoxy group.

[0058] Examples of epoxy compounds include compounds that at least partially contain a rod-like structure (rod-like compounds) and compounds that at least partially contain a disc-like structure (disco-like compounds). The rod-shaped compounds and discotic compounds will be described in detail below.

[0059] ·Rod-shaped compound Examples of epoxy compounds that are rod-shaped compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. In addition to the low molecular weight compounds described above, high molecular weight compounds can also be used. The high molecular weight compounds are polymerized low molecular weight rod-shaped compounds having reactive groups. A preferred rod-shaped compound is a rod-shaped compound represented by the following general formula (XXI). General formula (XXI):Q 1 -L 111 -A 111 -L 113 -ML 114 -A 112 -L 112 -Q 2

[0060] In general formula (XXI), Q 1 and Q 2 are each independently an epoxy group, and L 111 , L 112 , L 113 , and L 114 A each independently represents a single bond or a divalent linking group. 111 and A 112 each independently represents a divalent linking group (spacer group) having 1 to 20 carbon atoms. M represents a mesogenic group. Q 1 and Q 2 The epoxy group may or may not have a substituent.

[0061] In general formula (XXI), L 111 , L 112 , L 113 , and L 114 each independently represents a single bond or a divalent linking group. L 111 , L 112 , L 113 , and L 114The divalent linking groups represented by the formula (I) are each independently -O-, -S-, -CO-, -NR 112 -, -CO-O-, -O-CO-O-, -CO-NR 112 -, -NR 112 -CO-, -O-CO-, -CH2-O-, -O-CH2-, -O-CO-NR 112 -, -NR 112 -CO-O- and -NR 112 -CO-NR 112 - is preferably a divalent linking group selected from the group consisting of 112 is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. Among them, L 113 and L 114 are each independently preferably —O—. L 111 and L 112 are each independently preferably a single bond.

[0062] In general formula (XXI), A 111 and A 112 each independently represents a divalent linking group having 1 to 20 carbon atoms. The divalent linking group may contain heteroatoms such as non-adjacent oxygen atoms and sulfur atoms. Among these, alkylene groups, alkenylene groups, and alkynylene groups having 1 to 12 carbon atoms are preferred. The alkylene groups, alkenylene groups, and alkynylene groups may or may not have an ester group. The divalent linking group is preferably linear, and may or may not have a substituent, such as a halogen atom (fluorine atom, chlorine atom, or bromine atom), a cyano group, a methyl group, or an ethyl group. Among them, A 111 and A 112 are each independently preferably an alkylene group having 1 to 12 carbon atoms, more preferably a methylene group.

[0063] In general formula (XXI), M represents a mesogenic group, and examples of the mesogenic group include known mesogenic groups. Among these, a group represented by the following general formula (XXII) is preferred. General formula (XXII):-(W 1 -L 115 ) n -W 2 -

[0064] In general formula (XXII), W 1 and W 2 each independently represents a divalent cyclic alkylene group, a divalent cyclic alkenylene group, an arylene group, or a divalent heterocyclic group. 115 represents a single bond or a divalent linking group, and n represents an integer of 1 to 4.

[0065] W 1 and W 2 Examples of the cyclohexanediyl include 1,4-cyclohexenediyl, 1,4-cyclohexanediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl, 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, and pyridazine-3,6-diyl. In the case of 1,4-cyclohexanediyl, either the trans or cis structural isomer may be used, and a mixture of these isomers may be used in any proportion. Among these, the trans isomer is preferred for the 1,4-cyclohexanediyl. W 1 and W 2may each have a substituent. Examples of the substituent include the groups exemplified in the above-mentioned substituent group Y, and more specific examples include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), a cyano group, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, and a propyl group), an alkoxy group having 1 to 10 carbon atoms (for example, a methoxy group and an ethoxy group), an acyl group having 1 to 10 carbon atoms (for example, a formyl group and an acetyl group), an alkoxycarbonyl group having 1 to 10 carbon atoms (for example, a methoxycarbonyl group and an ethoxycarbonyl group), an acyloxy group having 1 to 10 carbon atoms (for example, an acetyloxy group and a propionyloxy group), a nitro group, a trifluoromethyl group, and a difluoromethyl group. W 1 If there are multiple W 1 may be the same or different.

[0066] In general formula (XXII), L 115 represents a single bond or a divalent linking group. 115 The divalent linking group represented by the formula (I) is the same as the above-mentioned L 111 ~L 114 Specific examples of the divalent linking group include -CO-O-, -O-CO-, -CH2-O-, and -O-CH2-. L 115 If there are multiple L 115 may be the same or different.

[0067] Preferred basic skeletons of the mesogenic group represented by the general formula (XXII) are exemplified below: The mesogenic group may have a substituent on the skeleton.

[0068] [ka]

[0069] [ka]

[0070] Among the above skeletons, the biphenyl skeleton is preferred in that the resulting thermally conductive material has better thermal conductivity. The compound represented by general formula (XXI) can be synthesized by referring to the method described in JP-A-11-513019 (WO97 / 00600). The rod-like compound may be a monomer having a mesogen group as described in JP-A-11-323162 and Japanese Patent No. 4118691.

[0071] Among them, the rod-like compound is preferably a compound represented by the general formula (E1).

[0072] [ka]

[0073] In general formula (E1), L E1 each independently represents a single bond or a divalent linking group. Among them, L E1 is preferably a divalent linking group. The divalent linking group is preferably -O-, -S-, -CO-, -NH-, -CH=CH-, -C≡C-, -CH=N-, -N=CH-, -N=N-, an optionally substituted alkylene group, or a group consisting of a combination of two or more of these, and more preferably -O-alkylene group- or -alkylene group-O-. The alkylene group may be linear, branched, or cyclic, but is preferably a linear alkylene group having 1 to 2 carbon atoms. Multiple Ls E1 may be the same or different.

[0074] In general formula (E1), L E2 are each independently a single bond, -CH=CH-, -CO-O-, -O-CO-, -C(-CH3)=CH-, -CH=C(-CH3)-, -CH=N-, -N=CH-, -N=N-, -C≡C-, -N=N + (-O - )-, -N+ (-O - )=N-, -CH=N + (-O - )-, -N + (-O - )=CH—, —CH=CH—CO—, —CO—CH=CH—, —CH=C(—CN)—, or —C(—CN)=CH—. Among them, L E2 are each independently preferably a single bond, -CO-O-, or -O-CO-. L E2 If there are multiple L E2 may be the same or different.

[0075] In general formula (E1), L E3 each independently represents a single bond, or an optionally substituted 5- or 6-membered aromatic ring group, an optionally substituted 5- or 6-membered non-aromatic ring group, or a polycyclic group consisting of these rings. L E3 Examples of aromatic and non-aromatic ring groups represented by the formula (I) include optionally substituted 1,4-cyclohexanediyl, 1,4-cyclohexenediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl, 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, and pyridazine-3,6-diyl groups. In the case of the 1,4-cyclohexanediyl group, either the trans or cis structural isomer may be used, or a mixture of these in any proportion may be used. Of these, the 1,4-cyclohexanediyl group is preferably the trans isomer. Among them, L E3 is preferably a single bond, a 1,4-phenylene group, or a 1,4-cyclohexenediyl group. L E3 The substituents on the group represented by the formula (I) are each independently preferably an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, or an acetyl group, and more preferably an alkyl group (preferably having 1 carbon atom). When a plurality of substituents are present, the substituents may be the same or different. L E3 If there are multiple L E3 may be the same or different.

[0076] In the general formula (E1), pe represents an integer of 0 or more. If pe is an integer greater than or equal to 2, there are multiple (-L E3 -L E2 -) may be the same or different. Among these, pe is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0077] In general formula (E1), L E4 each independently represents a substituent. The substituents are each independently preferably an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, or an acetyl group, and more preferably an alkyl group (preferably having 1 carbon atom). Multiple Ls E4 may be the same or different. In addition, when le, which will be explained next, is an integer of 2 or more, the same (L E4 ) le There are multiple L's in E4 may be the same or different.

[0078] In the general formula (E1), each le independently represents an integer of 0 to 4. In particular, it is preferable that each le is independently 0 to 2. Multiple le's may be the same or different.

[0079] The rod-like compound preferably has a biphenyl skeleton, since the resulting thermally conductive material has better thermal conductivity. In other words, the epoxy compound preferably has a biphenyl skeleton, and in this case, the epoxy compound is more preferably a rod-shaped compound.

[0080] ·Disk-shaped compounds The discotic epoxy compound has at least a partial discotic structure. The discotic structure has at least an alicyclic or aromatic ring. In particular, when the discotic structure has an aromatic ring, the discotic compound can form a columnar structure by forming a stacking structure due to intermolecular π-π interactions. Specific examples of the discotic structure include the triphenylene structure described in Angew. Chem. Int. Ed. 2012, 51, 7990-7993 or JP-A-7-306317, and the tri-substituted benzene structures described in JP-A-2007-2220 and JP-A-2010-244038.

[0081] If a discotic compound is used as the epoxy compound, a thermally conductive material with high thermal conductivity can be obtained. The reason for this is thought to be that while rod-shaped compounds can only conduct heat linearly (one-dimensionally), discotic compounds can conduct heat planarly (two-dimensionally) in the normal direction, which increases the number of heat conduction paths and improves thermal conductivity.

[0082] The discotic compound preferably has three or more epoxy groups. A cured product of a composition containing a discotic compound having three or more epoxy groups tends to have a high glass transition temperature and high heat resistance. The number of epoxy groups contained in the discotic compound is preferably 8 or less, more preferably 6 or less.

[0083] Specific examples of the discotic compound include compounds described in C. Destrade et al., Mol. Crysr. Liq. Cryst., vol. 71, page 111 (1981); Quarterly Review of Chemistry, No. 22, edited by the Chemical Society of Japan, Chemistry of Liquid Crystals, Chapter 5, Chapter 10, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., page 1794 (1985); J. Zhang et al., J. Am. Chem. Soc., vol. 116, page 2655 (1994), and Japanese Patent No. 4592225, in which at least one (preferably three or more) of the terminals is an epoxy group. Examples of the discotic compound include the triphenylene structure described in Angew. Chem. Int. Ed. 2012, 51, 7990-7993 and JP-A-7-306317, and the trisubstituted benzene structure described in JP-A-2007-2220 and JP-A-2010-244038 in which at least one (preferably three or more) of the terminals is an epoxy group.

[0084] Other epoxy compounds Examples of epoxy compounds other than the above-mentioned epoxy compounds include epoxy compounds represented by general formula (DN).

[0085] [ka]

[0086] In the general formula (DN), n DN represents an integer of 0 or more, preferably 0 to 5, and more preferably 1. R DN represents a single bond or a divalent linking group. The divalent linking group is preferably -O-, -O-CO-, -CO-O-, -S-, an alkylene group (preferably having 1 to 10 carbon atoms), an arylene group (preferably having 6 to 20 carbon atoms), or a group formed from a combination thereof, more preferably an alkylene group, and more preferably a methylene group.

[0087] Other examples of the epoxy compounds include glycidyl ethers of bisphenol A, F, S, AD, etc., such as bisphenol A epoxy compounds, bisphenol F epoxy compounds, bisphenol S epoxy compounds, and bisphenol AD ​​epoxy compounds; hydrogenated bisphenol A epoxy compounds, hydrogenated bisphenol AD ​​epoxy compounds, etc.; phenol novolac glycidyl ethers (phenol novolac epoxy compounds), cresol novolac glycidyl ethers (cresol novolac epoxy compounds), and bisphenol A novolac glycidyl ethers; dicyclopentadiene glycidyl ethers (dicyclopentadiene epoxy compounds); dihydroxypentadiene glycidyl ethers (dihydroxypentadiene epoxy compounds); polyhydroxybenzene glycidyl ethers (polyhydroxybenzene epoxy compounds); benzenepolycarboxylic acid glycidyl esters (benzenepolycarboxylic acid epoxy compounds); alicyclic epoxy compounds such as 3,4:8,9-diepoxybicyclo[4.3.0]nonane, and trisphenolmethane epoxy compounds. A compound in which one or more of the glycidyl ether groups and / or glycidyl ester groups in each of the above-mentioned compounds are replaced with a diglycidylamino group or a diglycidylaminoalkylene group (such as a diglycidylaminomethylene group) may be used as the epoxy compound. Each of the above compounds may have a substituent. For example, the aromatic ring group, cycloalkane ring group, and / or alkylene group contained in each of the above compounds may have a substituent other than a glycidyl ether group, a glycidyl ester group, a diglycidylamino group, and / or a diglycidylaminoalkylene group.

[0088] Among these, methylene bisphenol diglycidyl ether, such as glycidyl ether of bisphenol F, is preferred as the epoxy compound.

[0089] The epoxy compounds may be used alone or in combination of two or more.

[0090] (active hydrogen group-containing compound) The epoxy compound is preferably used in combination with an active hydrogen group-containing compound. The active hydrogen group-containing compound is a compound that has one or more (preferably two or more, more preferably 2 to 10) groups having active hydrogen (active hydrogen groups). Examples of the active hydrogen group include a hydroxyl group, a primary or secondary amino group, and a mercapto group, with a hydroxyl group being preferred. The active hydrogen group-containing compound is preferably a polyol having two or more (preferably three or more, more preferably three to six) hydroxyl groups.

[0091] Among these, the active hydrogen group-containing compound used in combination with the epoxy compound is preferably a phenol compound. That is, the thermosetting compound in the composition preferably contains an epoxy compound and a phenol compound. The phenol compound is a compound having one or more (preferably two or more, more preferably three or more, and even more preferably three to six) phenolic hydroxyl groups. In terms of achieving better effects of the present invention, the phenol compound is preferably a compound represented by general formula (P1).

[0092] A compound represented by general formula (P1) General formula (P1) is shown below.

[0093] [ka]

[0094] In the general formula (P1), m1 represents an integer of 0 or more. m1 is preferably 0 to 10, more preferably 0 to 3, further preferably 0 or 1, and particularly preferably 1.

[0095] In the general formula (P1), na and nc each independently represent an integer of 1 or more. Each of na and nc is preferably 1 to 4 independently.

[0096] In general formula (P1), R 1 and R 6 each independently represents a hydrogen atom, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group. The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 10. The alkyl group may or may not have a substituent. The alkyl group moiety in the alkoxy group and the alkyl group moiety in the alkoxycarbonyl group are the same as the alkyl group described above. R 1 and R 6 are each independently preferably a hydrogen atom or a halogen atom, more preferably a hydrogen atom or a chlorine atom, and even more preferably a hydrogen atom.

[0097] In general formula (P1), R 7 represents a hydrogen atom or a hydroxyl group. R 7 If there are multiple R 7 may be the same or different. R 7 If there are multiple R 7 At least one R 7 It is also preferred that represents a hydroxyl group.

[0098] In general formula (P1), L x1 is a single bond, -C(R 2 )(R 3 )- or -CO-, -C(R 2 )(R 3 )- or -CO- is preferred. L x2 is a single bond, -C(R 4 )(R 5 )- or -CO-, -C(R 4)(R 5 )- or -CO- is preferred. R 2 ~R 5 each independently represents a hydrogen atom or a substituent. The substituents are each independently preferably a hydroxyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group, and more preferably a hydroxyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkyl group, an alkoxy group, or an alkoxycarbonyl group. The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 10. The alkyl group may or may not have a substituent. The alkyl group moiety in the alkoxy group and the alkyl group moiety in the alkoxycarbonyl group are the same as the alkyl group described above. The phenyl group may or may not have a substituent, and when it has a substituent, it more preferably has 1 to 3 hydroxyl groups. R 2 ~R 5 are each independently preferably a hydrogen atom or a hydroxyl group, more preferably a hydrogen atom. L x1 and L x2 are each independently preferably —CH—, —CH(OH)—, —CO—, or —CH(Ph)—. The above Ph represents a phenyl group which may have a substituent. In general formula (P1), R 4 If there are multiple R 4 may be the same or different. 5 If there are multiple R 5 may be the same or different.

[0099] In general formula (P1), Ar 1 and Ar 2 each independently represents a benzene ring group or a naphthalene ring group. Ar 1and Ar 2 are each independently preferably a benzene ring group.

[0100] In general formula (P1), Q a represents a hydrogen atom, an alkyl group, a phenyl group, a halogen atom, a carboxylic acid group, a boronic acid group, an aldehyde group, an alkoxy group, or an alkoxycarbonyl group. The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 10. The alkyl group may or may not have a substituent. The alkyl group moiety in the alkoxy group and the alkyl group moiety in the alkoxycarbonyl group are the same as the alkyl group described above. The phenyl group may or may not have a substituent. Q a Q a is preferably bonded at the para position relative to the hydroxyl group that the benzene ring group to which it is bonded may have. Q a is preferably a hydrogen atom or an alkyl group, and the alkyl group is preferably a methyl group.

[0101] In addition, in general formula (P1), R 7 , L x2 , and / or Q a If there are multiple R 7 , L x2 , and / or Q a may be the same or different.

[0102] A compound represented by the general formula (Z) The phenol compound is also preferably a compound having a triazine skeleton. The phenol compound "having a triazine skeleton" means that the compound has one or more (for example, 1 to 5) triazine ring groups. Such phenol compounds include compounds represented by general formula (Z).

[0103] [ka]

[0104] In the above general formula (Z), when there are multiple groups represented by the same symbol, the multiple groups represented by the same symbol may be the same or different, unless otherwise specified.

[0105] In general formula (Z), E 1 ~E 6 each independently represents a single bond, —NH—, or —NR—. R represents a substituent, and examples of the substituent represented by R include linear or branched alkyl groups having 1 to 5 carbon atoms. E 1 ~E 6 are each independently preferably -NH- or -NR-, more preferably -NH-.

[0106] In general formula (Z), B 1 represents a single bond or a (k+1)-valent organic group. B 2 represents a single bond or an l+1-valent organic group. B 3 represents a single bond or an (m+1)-valent organic group. B 4 represents a single bond or an (n+1)-valent organic group. The values ​​of k, l, m, and n in the k+1-valent organic group, the l+1-valent organic group, the m+1-valent organic group, and the n+1-valent organic group are the same as the values ​​of k, l, m, and n specified in general formula (Z). In addition, if r is 2 or more and the values ​​of m are different, B 3 The value of m in the (m+1) valent organic group represented by 3 X to which 3 The value of m is the same as the number of

[0107] B 1 ~B 4Examples of the organic group represented by include groups in which j hydrogen atoms have been removed from a hydrocarbon having 1 to 20 carbon atoms and which may have a heteroatom. Here, j refers to k+1, l+1, m+1, or n+1. Here, examples of the hydrocarbon before removing j hydrogen atoms include one or more hydrocarbons selected from the group consisting of an aliphatic hydrocarbon having 1 to 20 carbon atoms which may have a substituent, an aliphatic ring having 3 to 20 carbon atoms which may have a substituent, and an aromatic ring having 3 to 20 carbon atoms which may have a substituent. In addition, the one or more hydrocarbons may further include -O-, -S-, -CO-, -NR N -(R N is a hydrogen atom or a substituent), and a structure formed by combining one or more divalent linking groups selected from the group consisting of -SO2-. Examples of aliphatic hydrocarbons having 1 to 20 carbon atoms include methane, ethane, propane, butane, pentane, hexane, and heptane. Examples of the aliphatic ring having 3 to 20 carbon atoms include a cyclohexane ring, a cycloheptane ring, a norbornane ring, and an adamantane ring. Examples of aromatic rings having 3 to 20 carbon atoms include aromatic hydrocarbons having 6 to 20 carbon atoms and aromatic heterocycles having 3 to 20 carbon atoms. Examples of aromatic hydrocarbons having 6 to 20 carbon atoms include a benzene ring, a naphthalene ring, and an anthracene ring. Examples of aromatic heterocycles having 3 to 20 carbon atoms include a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, a carbazole ring, an indole ring, and a benzothiazole ring.

[0108] In general formula (Z), k, l, m, and n each independently represent an integer of 0 or greater, provided that the sum of k, l, r×m, and n is 2 or greater, and is preferably an integer of 2 to 12, and more preferably an integer of 4 to 8. The value of m in "r×m" is the average value of multiple possible m's. k, l, m, and n each independently represent preferably 0 to 5, and more preferably 1 or 2. For example, k is preferably 1 or more (for example, 1 to 2), l is preferably 1 or more (for example, 1 to 2), m is preferably 1 or more (for example, 1 to 2), and n is preferably 1 or more (for example, 1 to 2). Note that if k is 0, B 1 is X 1 If l is 0, then B 2 is X 2 If m is 0, then B 3 is X 3 If n is 0, then B 4 is X 4 does not have. Also, B 1 If is a single bond, k is 1. 2 If is a single bond, l is 1. 3 If is a single bond, m is 1. 4 If is a single bond, n is 1.

[0109] L represents a divalent organic group. Examples of the organic group include an aromatic ring group which may have a substituent, an aliphatic hydrocarbon group which may have a substituent, an aliphatic ring group which may have a substituent, -O-, -S-, -N(R N )-, -CO-, and combinations thereof. R N represents a substituent. N Examples of the substituent represented by include a linear or branched alkyl group having 1 to 5 carbon atoms. Furthermore, examples of the substituent that the aromatic ring group, the aliphatic hydrocarbon group, and the aliphatic ring group may have include linear or branched alkyl groups having 1 to 5 carbon atoms.

[0110] Examples of the aromatic ring group include aromatic hydrocarbon groups having 6 to 20 carbon atoms and aromatic heterocyclic groups having 3 to 20 carbon atoms. Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include monocyclic aromatic ring groups such as a benzene ring; and polycyclic aromatic ring groups such as a naphthalene ring and an anthracene ring. Examples of aromatic heterocyclic groups having 3 to 20 carbon atoms include monocyclic aromatic ring groups such as a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, and a thiazole ring; and polycyclic aromatic ring groups such as a benzothiazole ring, a carbazole ring, and an indole ring. The aromatic ring group represented by L includes groups obtained by removing two hydrogen atoms from the above examples.

[0111] Examples of the aliphatic hydrocarbon group include alkylene groups having 1 to 12 carbon atoms, and specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a methylhexylene group, and a heptylene group.

[0112] Examples of the aliphatic ring group include a cyclohexane ring group, a cycloheptane ring group, a norbornane ring group, and an adamantane ring group. The aliphatic cyclic group represented by L may be any of the above-listed groups in which two hydrogen atoms have been removed.

[0113] an aromatic ring group which may have a substituent, an aliphatic hydrocarbon group which may have a substituent, an aliphatic ring group which may have a substituent, or -O-, -S-, -NR N The group combining - or -CO- may be not only a divalent linking group formed by combining two or more of these, but also a divalent linking group formed by combining two or more of the same type of groups (for example, aromatic ring groups) via a single bond.

[0114] In the present invention, it is preferable that both ends of L are carbon atoms, in order to obtain a thermally conductive material with better thermal conductivity. The terminal carbon atoms may be part of a cyclic structure. In addition, in the present invention, in order to obtain a thermally conductive material with better thermal conductivity, it is preferable that L in the above general formula (P2) is a divalent organic group having at least one selected from the group consisting of a divalent aromatic ring group which may have a substituent, a divalent aliphatic ring group which may have a substituent, and an alkylene group having two or more carbon atoms which may have a branch, and a divalent organic group having a divalent aromatic ring group which may have a substituent is more preferable in order to obtain better thermal conductivity.

[0115] In the general formula (Z), r is an integer of 0 or more. r is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10.

[0116] In general formula (Z), X 1 ~X 4 each independently represents an aromatic ring group having a phenolic hydroxyl group. The "aromatic ring group having a phenolic hydroxyl group" may be an aromatic ring group having one or more (e.g., 1 to 4) hydroxyl groups (phenolic hydroxyl groups) directly bonded to the aromatic ring. The aromatic ring group may or may not have a substituent other than the hydroxyl group. The aromatic ring group may be monocyclic or polycyclic, and may have a heteroatom as a ring member atom. The number of ring member atoms in the aromatic ring group is preferably 5 to 15, more preferably 6 to 10, and even more preferably 6. The aromatic ring group is preferably a benzene ring group. The substituent that the aromatic ring group may have other than the hydroxyl group is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a linear or branched alkyl group having 1 to 6 carbon atoms.

[0117] In the general formula (Z), k X's are present. 1 , there are l X 2 , r×m pieces of X 3 , and n X 4It is also preferred that at least one of the groups is an aromatic ring group having a phenolic hydroxyl group and a substituent located at the ortho-position of the phenolic hydroxyl group. The substituent may be located at only one or both of the ortho-positions of the phenolic hydroxyl group. The value of m in "r×m" is the average value of multiple possible m's. Furthermore, the "substituent located at the ortho position" is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a linear or branched alkyl group having 1 to 6 carbon atoms. In other words, there are (k+l+r×m+n) X 1 ~X 4 Among the "aromatic ring groups having a phenolic hydroxyl group" represented by any one of the above, at least one (preferably 30% or more, more preferably 50% or more, and even more preferably 65% ​​or more; preferably 100% or less, more preferably 90% or less, and even more preferably 80% or less) may represent an "aromatic ring group having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group".

[0118] X 1 ~X 4 In the aromatic ring group having a phenolic hydroxyl group represented by the formula (I), the aromatic ring group other than "an aromatic ring group having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group" may or may not have a substituent other than a hydroxyl group (phenolic hydroxyl group). Examples of aromatic ring groups other than "aromatic ring groups having a phenolic hydroxyl group and a substituent positioned at the ortho-position of the phenolic hydroxyl group" include hydroxyphenyl groups. There are (k+l+r×m+n) instances of X 1 ~X 4 It is also preferred that at least one (e.g., 1 to 2) of the "aromatic ring group having a phenolic hydroxyl group" represented by any one of the above is an aromatic ring group other than the "aromatic ring group having a phenolic hydroxyl group and a substituent positioned at the ortho-position of the phenolic hydroxyl group". X 1 ~X 4In the aromatic ring group having a phenolic hydroxyl group represented by the formula (I), the presence of aromatic ring groups other than "an aromatic ring group having a phenolic hydroxyl group and a substituent arranged at the ortho-position of the phenolic hydroxyl group" is thought to disrupt the symmetry of the compound as a whole, lower the melting point of the compound, and improve the handleability of a semi-cured film formed from the composition.

[0119] The phenol compound is also preferably a compound represented by general formula (Z1). The phenol compound preferably contains a compound represented by general formula (Z1), and the phenol compound may be the compound represented by general formula (Z1) itself. The content of the compound represented by general formula (Z1) is preferably 10 to 100 mass%, more preferably 25 to 100 mass%, and even more preferably 50 to 100 mass%, based on the total mass of the phenol compound.

[0120] [ka]

[0121] In formula (Z1), r represents an integer of 0 or greater. r is preferably an integer of 0 to 20, and more preferably an integer of 0 to 10. L represents a divalent organic group. The divalent organic group represented by L in general formula (Z1) is, for example, the same as the divalent organic group represented by L in general formula (Z1). R Z represents a hydrogen atom or a substituent. R Z The substituent represented by the formula (I) is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a linear or branched alkyl group having 1 to 6 carbon atoms. (3+r) R's present in general formula (Z1) Z At least one of (preferably 30% or more, more preferably 50% or more, even more preferably 65% ​​or more; preferably 90% or less, more preferably 80% or less) may represent a substituent. (3+r) R's present in general formula (Z1)Z At least one (for example, 1 to 2) of these may represent a hydrogen atom. R in general formula (Z1) z (Preferably, the substituent R z ) and OH-bonded benzene ring group, z (Preferably, the substituent R z ) is also preferably present at the para position relative to the NH bonded to the benzene ring group.

[0122] The phenol compound is also preferably a compound represented by general formula (Z2). The phenol compound preferably contains a compound represented by general formula (Z2), and the phenol compound may be the compound represented by general formula (Z2) itself. The content of the compound represented by general formula (Z2) is preferably 10 to 100 mass%, more preferably 25 to 100 mass%, and even more preferably 50 to 100 mass%, based on the total mass of the phenol compound.

[0123] [ka]

[0124] In general formula (Z2), R Z represents a hydrogen atom or a substituent. Two Rs Z At least one of these groups preferably represents a substituent, and both of these groups preferably represent a substituent. R Z The substituent represented by the following formula is preferably a substituent having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group may be linear or branched, and is preferably unsubstituted. Two R in general formula (Z2) z may be the same or different.

[0125] Other preferred phenol compounds include, for example, benzene polyols such as benzenetriol, biphenyl aralkyl phenol resins, phenol novolac resins, cresol novolac resins, aromatic hydrocarbon formaldehyde resin-modified phenol resins, dicyclopentadiene phenol addition resins, phenol aralkyl resins, polyhydric phenol novolac resins synthesized from polyhydric hydroxy compounds and formaldehyde, naphthol aralkyl resins, trimethylolmethane resins, tetraphenylolethane resins, naphthol novolac resins, naphtholphenol co-condensed novolac resins, naphthol-cresol co-condensed novolac resins, biphenyl-modified phenol resins, biphenyl-modified naphthol resins, aminotriazine-modified phenol resins, and alkoxy group-containing aromatic ring-modified novolac resins.

[0126] The lower limit of the hydroxyl group content of the phenol compound is preferably 3.0 mmol / g or more, more preferably 7.0 mmol / g or more, and the upper limit is preferably 25.0 mmol / g or less, more preferably 20.0 mmol / g or less. The hydroxyl group content refers to the number of hydroxyl groups (preferably phenolic hydroxyl groups) that 1 g of the phenol compound has. In addition to hydroxyl groups, the phenolic compound may have active hydrogen-containing groups (such as carboxylic acid groups) capable of polymerizing with the epoxy compound. The lower limit of the active hydrogen content (total content of hydrogen atoms in hydroxyl groups, carboxylic acid groups, etc.) of the phenolic compound is preferably 3.0 mmol / g or more, more preferably 7.0 mmol / g or more. The upper limit is preferably 25.0 mmol / g or less, more preferably 20.0 mmol / g or less. The active hydrogen content refers to the number of active hydrogen atoms contained in 1 g of the phenol compound.

[0127] The upper limit of the molecular weight of the phenol compound is preferably 600 or less, more preferably 500 or less, even more preferably 450 or less, and particularly preferably 400 or less. The lower limit is preferably 110 or more, more preferably 300 or more.

[0128] The phenol compounds may be used alone or in combination of two or more.

[0129] When the composition contains an epoxy compound and an active hydrogen group-containing compound, the ratio of the content of the epoxy compound to the content of the active hydrogen group-containing compound is such that the equivalent ratio ("number of epoxy groups" / "number of active hydrogen groups") of the epoxy group of the epoxy compound to the active hydrogen groups (preferably hydroxyl groups, more preferably phenolic hydroxyl groups) of the active hydrogen group-containing compound is preferably 30 / 70 to 70 / 30, more preferably 40 / 60 to 60 / 40, and even more preferably 45 / 55 to 55 / 45. When the composition contains an epoxy compound and / or an active hydrogen group-containing compound, the total content of the epoxy compound and the active hydrogen group-containing compound is preferably 20 to 100% by volume, more preferably 60 to 100% by volume, and even more preferably 90 to 100% by volume, based on the total binder components.

[0130] The content of the thermosetting compound in the composition (preferably the total content of the epoxy compound and the active hydrogen group-containing compound used in combination with the epoxy compound) is preferably 5 to 90% by volume, more preferably 10 to 50% by volume, and even more preferably 20 to 45% by volume, based on the total solid content of the composition.

[0131] <Curing accelerator> The composition may further comprise a cure accelerator. The type of curing accelerator to be used may be appropriately determined taking into consideration the type of thermosetting compound, etc.

[0132] Examples of the curing accelerator include tris-orthotolylphosphine, triphenylphosphine, boron trifluoride amine complex, and the compounds described in paragraph 0052 of JP 2012-067225 A. Other examples include onium salt-based curing accelerators such as quaternary phosphonium compounds (phosphonium salts) such as tetraphenylphosphonium tetraphenylborate (TPP-K), tetraphenylphosphonium tetra-p-tolylborate (TPP-MK), tetra-n-butylphosphonium laurate (TBP-LA), bis(tetra-n-butylphosphonium)pyromellitate, and tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate adducts. Other examples include 2-methylimidazole (trade name: 2MZ), 2-undecylimidazole (trade name: C11-Z), 2-heptadecylimidazole (trade name: C17Z), 1,2-dimethylimidazole (trade name: 1.2DMZ), 2-ethyl-4-methylimidazole (trade name: 2E4MZ), 2-phenylimidazole (trade name: 2PZ), 2-phenyl-4-methylimidazole (trade name: 2P4MZ), 1-benzyl-2-methylimidazole (trade name: 1B2MZ), 1-benzyl-2-methylimidazole (trade name: 1B2MZ), 1-benzyl-4-methylimidazole (trade name: 1B4 ... 1-cyanoethyl-2-phenylimidazole (trade name: 1B2PZ), 1-cyanoethyl-2-methylimidazole (trade name: 2MZ-CN), 1-cyanoethyl-2-undecylimidazole (trade name: C11Z-CN), 1-cyanoethyl-2-phenylimidazolium trimellitate (trade name: 2PZCNS-PW), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2MZ-A), 2,4-diamino-6-[2'-undecylimidazolyl -(1')]-ethyl-s-triazine (trade name: C11Z-A), 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2E4MZ-A), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (trade name: 2MA-OK), 2-phenyl-4,5-dihydroxymethylimidazole (trade name: 2PHZ-PW), 2-phenyl-4-methyl-5- ... Examples of suitable curing accelerators include imidazole-based curing accelerators such as phenylimidazole (trade name: 2P4MHZ-PW), 1-cyanoethyl-2-phenylimidazole (trade name: 2PZ-CN), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2MZA-PW), and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (trade name: 2MAOK-PW) (all manufactured by Shikoku Chemical Industry Co., Ltd.). Furthermore, examples of suitable curing accelerators include the compounds described in paragraph 0052 of JP-A-2004-043405.Examples of phosphorus-based curing accelerators in which triphenylborane is added to triarylphosphine include the compounds described in paragraph 0024 of JP-A No. 2014-005382. These curing accelerators are preferably used particularly when the composition contains an epoxy compound as the thermosetting compound.

[0133] In particular, the curing accelerator preferably contains a compound containing a phosphorus atom, which may be a phosphonium salt or other compounds. The content of the compound containing a phosphorus atom is preferably from 10 to 100 mass %, more preferably from 50 to 100 mass %, and even more preferably from 80 to 100 mass %, based on the total mass of the curing accelerator.

[0134] The curing accelerator may be used alone or in combination of two or more. For example, when the composition contains an epoxy compound, the content of the curing accelerator is preferably 0.01 to 10% by volume, more preferably 0.10 to 5% by volume, based on the total amount of the epoxy compound.

[0135] <Solvent> The composition may further comprise a solvent. The type of solvent is not particularly limited, but is preferably an organic solvent, such as cyclopentanone, cyclohexanone, ethyl acetate, methyl ethyl ketone, dichloromethane, and tetrahydrofuran. When the composition contains a solvent, the content of the solvent is preferably an amount that makes the solids concentration of the composition 20 to 90% by volume, more preferably an amount that makes 30 to 80% by volume, and even more preferably an amount that makes 40 to 60% by volume. That is, when the composition contains a solvent, the content thereof is preferably 10 to 80% by volume, more preferably 20 to 70% by volume, and even more preferably 40 to 60% by volume, based on the total amount of the composition.

[0136] <Other ingredients> The composition may contain other ingredients in addition to those mentioned above. Examples of other components include an ion scavenger, a dispersant, and a polymerization initiator (such as a photopolymerization initiator or a thermal polymerization initiator).

[0137] The method for producing the composition is not particularly limited, and any known method can be used. For example, the composition can be produced by mixing the various components described above. When mixing, the various components may be mixed all at once or sequentially. The method for mixing the components is not particularly limited, and known methods can be used. The mixing device used for mixing is preferably a submerged disperser, and examples include agitators such as planetary centrifugal mixers and high-speed rotary shear agitators, colloid mills, roll mills, high-pressure injection dispersers, ultrasonic dispersers, bead mills, and homogenizers. One type of mixing device may be used alone, or two or more types may be used. Degassing treatment may be performed before, after, and / or simultaneously with mixing.

[0138] The components (solid contents) described above as components that can be contained in the composition or components derived from the above components are exemplified as components that can be contained in the film. Furthermore, the preferred range of the content of each component (solid content) that may be contained in the composition relative to the total solid content of the composition is the same as the preferred range of the content of each of the above components (solid content) or components derived from each of the above components relative to the total volume of the film. For example, the preferred range of the content of the inorganic substance in the film relative to the total volume of the film coincides with the preferred range of the content of the inorganic substance contained in the composition relative to the total solid content of the composition. The preferred range of the content of the thermosetting compound in the film relative to the total volume of the film is the same as the preferred range of the content of the thermosetting compound contained in the composition relative to the total solid content of the composition. Note that the thermosetting compound may be in the process of curing in the film. The preferred range of the content of the curing accelerator in the film relative to the total volume of the film coincides with the preferred range of the content of the curing accelerator contained in the composition relative to the total solid content of the composition.

[0139] 〔glue〕 The adhesive layer of the thermally conductive layer-forming sheet is usually formed with an adhesive. There are no limitations on the adhesive, and it may be, for example, a heat-curing adhesive, a light-curing adhesive, a dry-curing adhesive, or a pressure-sensitive adhesive. It may also be an adhesive that combines a plurality of these adhesive modes.

[0140] As the adhesive, for example, a composition that does not contain inorganic substances or has a reduced content of inorganic substances in the above-mentioned composition (film-forming composition) can also be used. For example, the adhesive may contain a thermosetting compound, and the content thereof (preferably the total content of the epoxy compound and the active hydrogen group-containing compound used in combination with the epoxy compound) is preferably 50 to 100% by volume, more preferably 75 to 100% by volume, and even more preferably 95% by volume or more but less than 100% by volume, based on the total solid content of the adhesive. Similarly, the adhesive may contain a curing accelerator, the content of which is preferably 0.01 to 10% by volume, more preferably 0.10 to 5% by volume, based on the total amount of epoxy compounds in the adhesive. The adhesive may or may not contain an inorganic substance. The content (volume %) of the inorganic substance in the adhesive relative to the total solid content in the composition (film-forming composition) is preferably 0 to 1, more preferably 0 to 0.2, and even more preferably 0 to 0.02. More specifically, the content of the inorganic substance in the adhesive is preferably 0 to 20% by volume, more preferably 0 to 10% by volume, and even more preferably 0 to 3% by volume, based on the total solid content of the adhesive. Other preferable conditions for the thermosetting composition, curing accelerator, solvent, and inorganic substance that can be contained in the adhesive are the same as those for the thermosetting composition, curing accelerator, solvent, and inorganic substance that can be contained in the above-mentioned composition (film-forming composition). The adhesive may contain other ingredients that can be contained in the above-mentioned composition (film-forming composition).

[0141] The total solid content of the adhesive refers to the components that form the cured product of the adhesive, and does not include the solvent. The components that form the cured product may be components that undergo a reaction (polymerization, etc.) to change their chemical structure when forming the cured product. Furthermore, any component that forms the cured product is considered to be a solid content even if it is in a liquid state.

[0142] If the adhesive contains a solvent, it is preferable to volatilize and remove the solvent after applying the adhesive, and it is also preferable that the adhesive is substantially free of solvent at the time the adhesive layer is formed. An adhesive that is substantially free of solvent means that the solvent content is, for example, 0 to 2% by volume, preferably 0 to 1% by volume, and more preferably 0 to 0.1% by volume, relative to the total amount of the adhesive.

[0143] [Method for manufacturing a sheet for forming a thermally conductive layer] The method for producing the sheet for forming a thermally conductive layer is not particularly limited as long as the sheet for forming a thermally conductive layer produced satisfies the predetermined requirements. Among these, examples of the method for producing a sheet for forming a thermally conductive layer include the first and second methods described below. The first and second embodiments will be described below.

[0144] <First form> The first embodiment of the method for producing a sheet for forming a thermal conductive layer includes a film forming step of forming a film using a composition (film-forming composition), and an adhesive layer forming step of disposing an adhesive layer on a part of the surface of the film. However, the film satisfies requirement 1, and the adhesive layer satisfies requirement 2. The composition (film-forming composition), the adhesive, requirement 1, and requirement 2 are as described above.

[0145] (Film forming process) In the film-forming process, the composition is typically applied onto a substrate to form a film. Specifically, for example, a method of forming a coating film by applying a composition onto a substrate can be mentioned. The coating film is formed into the film as it is or after being appropriately treated. The substrate may be, for example, a release sheet (such as a polyester film having a release surface).

[0146] The resulting coating film is also preferably subjected to a heat treatment. In the heat treatment, the heating temperature is preferably 35 to 170° C., more preferably 50 to 150° C., and even more preferably 110 to 130° C. The treatment time is preferably 1 to 60 minutes, more preferably 2 to 30 minutes, and even more preferably 3 to 10 minutes. When the composition contains a solvent, the heat treatment is preferably used to volatilize and remove the solvent from the coating film. The heat treatment may also be intended to partially promote the reaction of the thermosetting compound in the coating film.

[0147] The heat treatment may be carried out under normal pressure or under pressure. The coating film may be subjected to press working before and / or after the heat treatment. There are no limitations on the press used for the press processing, and for example, a plate press or a roll press may be used. Furthermore, the press may or may not be a heat press. When using a roll press, for example, it is preferable to sandwich the coated substrate obtained by forming a coating film on the substrate between a pair of opposing rolls, and apply pressure in the film thickness direction of the coated substrate while rotating the pair of rolls to pass the coated substrate. The coated substrate may have a substrate on only one side of the coating film, or may have a substrate on both sides of the coating film. The coated substrate may be passed through the roll press once or multiple times. Either the treatment by platen pressing or the treatment by roll pressing may be carried out, or both may be carried out.

[0148] The film forming step may be completed when the coating film is in an A-stage state, or may be completed when the coating film is in a B-stage state. That is, the film formed in the film forming step may be a film in an A-stage state or a film in a B-stage state.

[0149] However, in the film forming step, the arithmetic mean roughness Ra of the surface of the adhesive layer side of the formed film needs to be adjusted so as to satisfy the above-mentioned requirement 1. The arithmetic mean roughness Ra of the film can be adjusted, for example, by appropriately setting the average particle size and content of the inorganic substance contained in the composition used to form the film (film-forming composition), as well as the pressing conditions. In the film forming step, separately produced films may be laminated together to form a single film, as long as the film finally formed satisfies predetermined requirements.

[0150] (Adhesive layer formation process) In the adhesive layer forming step, an adhesive layer that satisfies the above-mentioned requirement 2 is disposed on the surface of the film. In the adhesive layer forming step, for example, an adhesive is applied to form a predetermined adhesive layer.

[0151] In the adhesive layer forming step, the adhesive may be applied directly to the surface of the film, thereby disposing the adhesive layer on the surface of the film. If the adhesive applied to the film contains a solvent, it is also preferable to carry out a solvent removal treatment, which may be carried out at room temperature (for example, 5°C or higher and lower than 35°C) or at elevated temperatures (35°C or higher).

[0152] In the adhesive layer forming step, an adhesive may be applied to the surface of a release sheet to form an adhesive transfer layer on the surface of the release sheet. The adhesive transfer layer formed on the surface of the release sheet may be transferred to the surface of the film, and an adhesive layer may be disposed on the surface of the film. If the adhesive applied to the release sheet contains a solvent, it is also preferable to carry out a solvent removal process before transferring. The solvent removal process may be carried out at room temperature (for example, 5°C or higher and lower than 35°C) or at elevated temperatures (35°C or higher). The transfer can be performed, for example, by laminating the surface of the release sheet on which the adhesive transfer layer is formed to the film, whereby the adhesive transfer layer is transferred onto the surface of the film to form an adhesive layer. The release sheet used for the transfer may be used as it is as a protective sheet for the sheet for forming a thermally conductive layer.

[0153] The adhesive layer forming step may be carried out on one or both surfaces of the film. When preparing a sheet for forming a thermally conductive layer having adhesive layers on both sides of the film, the adhesive layers on both sides may be formed by applying an adhesive directly to the surface of the film, or the adhesive layers on both sides may be formed by transferring an adhesive transfer layer to the surface of the film, or the adhesive layer on one side may be formed by applying an adhesive directly to the surface of the film, while the adhesive layer on the other side may be formed by transferring an adhesive transfer layer to the surface of the film.

[0154] There are no limitations on the method of applying the adhesive in the adhesive layer forming step (for example, applying the adhesive directly to the surface of the film as described above, and applying the adhesive to the surface of a release sheet), and any of the following methods may be used: spray application, screen printing, gravure printing, and inkjet printing. The adhesive may be applied directly to the surface of the film, or may be applied to the surface of a release sheet. However, when applying the adhesive, care must be taken to ensure that the adhesive layer formed on the surface of the film satisfies the above-mentioned requirement 2. For example, when applying an adhesive to the surface of a release sheet, the adhesive transfer layer formed thereby must satisfy the above-mentioned requirement 2 when transferred into an adhesive layer. The adhesive may be applied in any manner as long as it can form the desired adhesive layer. For example, it is preferable to apply the adhesive so that areas where the adhesive is applied and areas where the adhesive is not applied are mixed within a narrow area. The adhesive may be applied, for example, in a dot pattern, a stripe pattern, a grid pattern, a tortoiseshell pattern, a random pattern, or a combination of these.

[0155] <Second form> A second embodiment of the method for manufacturing a sheet for forming a thermal conductive layer includes: an adhesive layer forming step of applying an adhesive to a release sheet to form an adhesive layer; and a film forming step of forming a film that satisfies requirement 1 using a composition (film-forming composition) on the surface of the release sheet on which the adhesive layer is formed, and disposing the adhesive layer on the surface of the film. However, the adhesive layer disposed on the surface of the film in the film-forming process satisfies requirement 2. The composition (film-forming composition), the adhesive, requirement 1, and requirement 2 are as described above.

[0156] (Adhesive layer formation process) In the adhesive layer forming step, an adhesive is applied onto the release sheet to form an adhesive layer on the release sheet. When the adhesive applied to the release sheet contains a solvent, it is also preferable to carry out a solvent removal treatment. The solvent removal treatment may be carried out at room temperature (for example, 5°C or higher and lower than 35°C) or at elevated temperatures (35°C or higher). Care should be taken to ensure that the adhesive layer formed on the release sheet satisfies Requirement 2 when it comes into contact with the film in the film formation step described below. There are no limitations on the method for applying the adhesive in the adhesive layer forming step, and any of spray coating, screen printing, gravure printing, and inkjet printing may be used, for example. The adhesive may be applied in any manner as long as it can form the desired adhesive layer. For example, it is preferable to apply the adhesive so that areas where the adhesive is applied and areas where the adhesive is not applied are mixed within a narrow area. The adhesive may be applied, for example, in a dot pattern, a stripe pattern, a grid pattern, a tortoiseshell pattern, a random pattern, or a combination of these.

[0157] (Film forming process) In the film forming step, the film is formed using a composition (film-forming composition) on the surface of the release sheet used in the adhesive layer forming step on which the adhesive layer has been formed. An adhesive layer is disposed on the surface of the film formed in the film forming step (the surface on the interface side with the release sheet).

[0158] In the film forming step, the composition is usually applied to the surface of the release sheet on which the adhesive layer has been formed to form a coating film, and the coating film is then formed into the film as is or after being appropriately treated.

[0159] The coating film obtained by applying the composition is also preferably subjected to a heat treatment. In the heat treatment, the heating temperature is preferably 35 to 170° C., more preferably 50 to 150° C., and even more preferably 110 to 130° C. The treatment time is preferably 1 to 60 minutes, more preferably 2 to 30 minutes, and even more preferably 3 to 10 minutes. When the composition contains a solvent, the heat treatment is preferably used to volatilize and remove the solvent from the coating film. The heat treatment may also be intended to partially promote the reaction of the thermosetting compound in the coating film.

[0160] The heat treatment may be carried out under normal pressure or under pressure. The coating film may be subjected to press working before and / or after the heat treatment. The conditions for the press working may be the same as those given in the description of the first embodiment.

[0161] The film forming step may be completed when the coating film is in an A-stage state, or may be completed when the coating film is in a B-stage state. That is, the film formed in the film forming step may be a film in an A-stage state or a film in a B-stage state.

[0162] However, in the film forming step, the arithmetic mean roughness Ra of the surface of the adhesive layer side of the formed film needs to be adjusted so as to satisfy the above-mentioned requirement 1. The arithmetic mean roughness Ra of the film can be adjusted by, for example, appropriately setting the average particle size or content of the inorganic substance contained in the composition used to form the film, or the pressing conditions. In addition, the film-forming step is preferably carried out so as to form a film that satisfies the above-mentioned preferred conditions. In the film forming step, a separately prepared film may be laminated to the formed film.

[0163] In a second embodiment of the method for manufacturing a sheet for forming a thermal conductive layer, the adhesive layer forming process described in the first embodiment may be further carried out on the surface of the film formed in the film forming process opposite to the release sheet to which the composition is applied in the film forming process.

[0164] In addition, in the first or second form, two sheets for forming a thermally conductive layer may be prepared in which an adhesive layer is disposed on only one side of the film, and the surfaces of the two sheets for forming a thermally conductive layer that do not have the adhesive layer may be bonded together to form a single sheet for forming a thermally conductive layer. In this case, the two sheets for forming a thermally conductive layer may be laminated together with another layer (such as the above-mentioned film having no adhesive layer on either side) interposed therebetween.

[0165] [Method for curing the sheet for forming a thermally conductive layer] The sheet for forming a thermally conductive layer of the present invention is subjected to a curing treatment to obtain a thermally conductive layer. The method for curing the sheet for forming a thermally conductive layer is preferably thermal curing. The heating temperature during the thermosetting reaction is not particularly limited and may be appropriately selected within the range of, for example, 50 to 250° C. Furthermore, when carrying out the thermosetting reaction, heat treatments at different temperatures may be carried out multiple times. When the curing treatment is carried out, it is preferable to cure the sheet for forming a thermally conductive layer in a state where the sheet is in contact with an object (adherend) to which heat is to be transferred. The curing treatment may be carried out by bringing the adherend into contact with only one side of the sheet for forming a thermally conductive layer, or by bringing the adherend into contact with each of both sides of the sheet. When the sheet for forming a thermal conductive layer is brought into contact with the adherend and / or when the sheet for forming a thermal conductive layer is subjected to a curing treatment while being in contact with the adherend, press working may be performed. There are no limitations on the press used for press working, and for example, a flat press or a roll press may be used. When using a roll press, for example, it is preferable to sandwich the coated substrate obtained by forming a coating film on the substrate between a pair of opposing rolls, and apply pressure in the film thickness direction of the coated substrate while rotating the pair of rolls to pass the coated substrate. The coated substrate may have a substrate on only one side of the coating film, or may have a substrate on both sides of the coating film. The coated substrate may be passed through the roll press once or multiple times. Either the treatment by platen pressing or the treatment by roll pressing may be carried out, or both may be carried out.

[0166] [Uses of the thermal conductive layer forming sheet] The thermally conductive layer formed using the sheet for forming a thermally conductive layer can be used as a heat dissipation material and can be used for heat dissipation purposes in various devices. More specifically, a device with a thermally conductive layer is produced by disposing the thermally conductive layer of the present invention on a device, and the heat generated from the device can be efficiently dissipated by the thermally conductive layer. The thermally conductive layer has sufficient thermal conductivity as well as high adhesiveness and heat resistance, making it suitable for heat dissipation applications in power semiconductor devices used in a variety of electrical equipment, including personal computers, general home appliances, and automobiles.

[0167] The thermally conductive layer formed using the sheet for forming a thermally conductive layer may be used in combination with other members. For example, the heat conductive layer may be combined with another support. The support may be a plastic film, a metal film, or a glass plate. Examples of materials for the plastic film include polyesters such as polyethylene terephthalate (PET), polycarbonates, acrylic resins, epoxy resins, polyurethanes, polyamides, polyolefins, cellulose derivatives, and silicones. Examples of metal films include copper films. [Example]

[0168] The present invention will be described in more detail below with reference to the following examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0169] [Composition] A composition (film-forming composition) was prepared using the materials shown below.

[0170] [Inorganic substances] The inorganic substances used in the examples and comparative examples are listed below. HP40-MF100: Agglomerated boron nitride, average particle size 40 μm, manufactured by Mizushima Ferroalloy Co., Ltd. HP40-J2W: Agglomerated boron nitride, average particle size 20 μm, manufactured by Mizushima Ferroalloy Co., Ltd. PTX-60: Agglomerated boron nitride, average particle size 60 μm, manufactured by Momentive

[0171] [Thermosetting compound] The thermosetting compounds used in the examples and comparative examples are shown below. In addition, A-1 below corresponds to an epoxy compound, and B-1 corresponds to a phenol compound.

[0172] [ka]

[0173] [Curing accelerator] TPP-MK (tetraphenylphosphonium tetra-p-tolylborate) was used as a curing accelerator.

[0174] 〔solvent〕 The solvents used in the examples and comparative examples are shown below. CPO: Cyclopentanone

[0175] [Preparation of Composition] Mixtures were prepared by blending the combinations of epoxy compounds and phenol compounds shown in the table below in equivalent amounts (amounts in which the number of epoxy groups in the epoxy compound is equal to the number of hydroxyl groups in the phenol compound in the system). The mixture, solvent, and curing accelerator were mixed in this order, and then boron nitride was added to obtain a mixture, which was then processed for 5 minutes in a planetary centrifugal mixer (THINKY Corporation, Awatori Rentaro ARE-310) to obtain a composition (thermal conductive material-forming composition) for each example or comparative example.

[0176] The amount of solvent added was determined so that the solid content of the composition would be as shown in the table below. The amount of the curing accelerator added was set so that the content of the curing accelerator in the composition was 3% by volume relative to the content of the epoxy compound. The total amount of the epoxy compound, phenol compound, and curing accelerator added was adjusted so that the total content (volume %) of the epoxy compound, phenol compound, and curing accelerator relative to the total solid content of the composition would be as shown in the table below. The addition amount of the inorganic substance was adjusted so that the content (volume %) of the inorganic substance with respect to the total solid content of the composition would be as shown in the table presented later. Incidentally, the total content (volume %) of the epoxy compound, the phenol compound, and the curing accelerator with respect to the total solid content in the composition is substantially the same as the total content (volume %) of the components derived from the epoxy compound, the phenol compound, and the curing accelerator with respect to the total volume of the formed film. Incidentally, the content (volume %) of the inorganic substance with respect to the total solid content in the composition is substantially the same as the content (volume %) of the inorganic substance with respect to the total volume of the formed film.

[0177] [Adhesive] The adhesive was prepared by mixing A-1 (epoxy compound), B-1 (phenol compound), TPP-MK (curing accelerator), and CPO (solvent) used in the above composition (composition for film formation). More specifically, first, a mixture was prepared by blending a combination of an epoxy compound and a phenol compound in an equivalent amount (an amount such that the number of epoxy groups of the epoxy compound and the number of hydroxyl groups of the phenol compound in the system are equal). Next, the above mixture, the solvent, and the curing accelerator were mixed in this order to obtain an adhesive. Incidentally, the addition amount of the solvent was set to an amount such that the solid content concentration of the adhesive would be 30 volume %. The addition amount of the curing accelerator was set to an amount such that the content of the curing accelerator in the adhesive would be 3 volume % with respect to the content of the epoxy compound. In the adhesive, the total content (volume %) of the epoxy compound, the phenol compound, and the curing accelerator with respect to the total solid content of the adhesive is 100%.

[0178] [Test] [Production of Film] [Production of Film in A Stage State] Using an applicator, the prepared composition (film-forming composition) was uniformly applied onto the release surface of a polyester film (PET75 6501 manufactured by Lintec Corporation, film thickness 75 μm) that had been subjected to a release treatment, to obtain a coating film. The polyester film with the coating film was left standing at 120 °C for 5 minutes, and the coating film was made into a film in the A-stage state (A-stage product).

[0179] <Production of Film in B-Stage State> If desired, the above A-stage product was made into a film in the B-stage state (B-stage product). Another new polyester film was further laminated onto the above A-stage product on the polyester film such that the release surfaces faced each other, to obtain a laminate having a structure of "polyester film - A-stage product - polyester film". The laminate was subjected to a roll press treatment at 100 °C. As a result, the above A-stage product was made into a film in the B-stage state (B-stage product). Regarding the above B-stage product, its viscosity was 10 4 Pa·s to 10 5 Pa·s at room temperature (25 °C), and 10 2 Pa·s to 10 3 Pa·s at 100 °C. This was confirmed. The viscosity of the above A-stage product was less than 10 2 Pa·s at 100 °C. Also, the above viscosity was measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 °C / min).

[0180] <Production of Film in C-Stage State> If desired, the above B-stage product was made into a film in the C-stage state (C-stage product). The laminate after roll press (laminate having a structure of "polyester film - B-stage product - polyester film") was subjected to high-pressure hot press in air (treated at a hot plate temperature of 180 °C and a pressure of 20 MPa for 5 minutes), then low-pressure hot press (treated at a hot plate temperature of 180 °C and a pressure of 5 MPa for 5 minutes), and further post-curing treatment at 180 °C for 90 minutes under normal pressure, to make the above B-stage product into a film in the C-stage state (C-stage product).

[0181] <Measurement of arithmetic mean roughness Ra of film> The arithmetic mean roughness Ra of the films (A-stage, B-stage, or C-stage products) prepared by the above method was determined as follows: The film surface was observed at 100x magnification using a Keyence VK-9710 laser microscope, and measurements were made based on JIS B0601 (2001) using an analytical application. When a polyester film was attached to the surface on which the arithmetic mean roughness Ra of the film was to be measured, the polyester film was removed before the measurement. The arithmetic mean roughness Ra was substantially the same on both sides of the film. Even when an adhesive layer was subsequently placed on the surface of the film, the arithmetic mean roughness Ra of the film did not substantially change.

[0182] [Preparation of adhesive layer (preparation of sheet for forming thermal conductive layer)] The above-mentioned adhesive was applied to the entire surface of each of the films (A-stage, B-stage, or C-stage products) produced by the above-mentioned method using a spray coating method, so as to achieve the coverage shown in the table below. Before applying the adhesive, if any polyester film was attached to the surface of the film, it was removed in advance. The adhesive applied to the film was dried at room temperature (25°C) to make the adhesive substantially solvent-free, forming an adhesive layer on the surface of the film. The amount of adhesive applied was set so that the average thickness of the adhesive layer formed would be 7 μm. In all of the Examples and Comparative Examples, the formed adhesive layer was a dot-shaped adhesive layer, and the average major axis of each dot (each adhesive portion) was within the range of 10 to 50 μm. Onto the adhesive layer of the thus obtained film with an adhesive layer (sheet for forming a thermally conductive layer), a new polyester film was laminated so that the release surface faced. Thereafter, an adhesive layer was formed on the surface of the sheet for forming a thermally conductive layer on which no adhesive layer was formed, and the polyester film was then attached. In this way, a laminate for forming a thermally conductive layer having a structure of "polyester film-sheet for forming a thermally conductive layer-polyester film" was obtained.

[0183] The coverage rate of the adhesive layer formed on the film (the proportion of the area of ​​the film covered by the adhesive) was measured by the following method. Specifically, the coverage of the adhesive layer was observed from an SEM image of the thermal conductive layer-forming sheet. More specifically, the coverage was calculated by averaging the percentage of the area where the adhesive was present on the surface in 10 randomly selected points within the surface of the thermal conductive layer-forming sheet.

[0184] [Measurement of thermal conductivity (W / m·k)] The laminate for forming a thermally conductive layer having the above-mentioned "polyester film-sheet for forming a thermally conductive layer-polyester film" configuration was subjected to high-pressure heat pressing under air (treatment for 5 minutes at a hot plate temperature of 180°C and a pressure of 20 MPa), followed by low-pressure heat pressing (treatment for 5 minutes at a hot plate temperature of 180°C and a pressure of 5 MPa), and then further heat treatment at 180°C for 90 minutes under normal pressure. Thereafter, the polyester film was peeled off from the laminate for forming a thermally conductive layer to obtain a resin sheet (thermally conductive layer) having an average thickness of 140 μm. (In other words, by carrying out the above-described treatment, the amount of composition applied (film thickness) when producing an A-stage product is appropriately adjusted so as to achieve the above-described average film thickness.)

[0185] The thermal conductivity of the resin sheet was measured by the following method. (1) The thermal diffusivity of the resin sheet in the thickness direction was measured by the laser flash method using the "LFA467" manufactured by NETZSCH. (2) Using a Mettler-Toledo balance "XS204," the specific gravity of the resin sheet was measured using the Archimedes method ("Solid Specific Gravity Measurement Kit"). (3) Using a DSC320 / 6200 manufactured by Seiko Instruments Inc., the specific heat of the resin sheet at 25°C was determined under the condition of a temperature increase of 10°C / min. (4) The thermal conductivity of the resin sheet was calculated by multiplying the obtained thermal diffusivity by the specific gravity and specific heat.

[0186] The measured thermal conductivity was classified according to the following criteria to evaluate the thermal conductivity in the film thickness direction. "A": 13W / m·K or more "B": 10 W / m·K or more and less than 13 W / m·K "C": 8 W / m K or more and less than 10 W / m K "D": Less than 8W / m·K

[0187] [Measurement of Adhesion (Copper Foil Peel Strength)] The polyester film on one side was peeled off from the thermally conductive layer-forming laminate having the above-mentioned "polyester film-thermally conductive layer-forming sheet-polyester film" configuration, and the sheet for forming a thermally conductive layer was placed on an aluminum plate so that it was in direct contact with the aluminum plate, and then subjected to high-pressure heat pressing in air (heat plate temperature 100°C, pressure 20 MPa, treatment for 1 minute). Thereafter, the polyester film attached to the other side of the sheet for forming a thermally conductive layer was peeled off to obtain an aluminum plate with the sheet for forming a thermally conductive layer. Copper foil was further laminated onto the sheet for forming a thermally conductive layer of the aluminum plate with the sheet for forming a thermally conductive layer, to obtain a laminate having a configuration of "aluminum plate-sheet for forming a thermally conductive layer-copper foil." The laminate was subjected to low-pressure heat pressing under air (heat plate temperature 180°C, pressure 5 MPa for 5 minutes), and further heat-treated at 180°C for 90 minutes under normal pressure to obtain a sample for peel strength measurement.

[0188] The copper foil peel strength of the obtained peel strength measurement sample was measured using a digital force gauge (ZTS-200N, manufactured by Imada Co., Ltd.) and a 90-degree peel test jig (P90-200N-BB, manufactured by Imada Co., Ltd.) according to the method for measuring peel strength under normal conditions described in JIS C 6481. In the peel strength test, the copper foil was peeled at an angle of 90° to the peel strength measurement sample at a peel rate of 50 mm / min.

[0189] The measured peel strength (copper foil peel strength) was classified according to the following criteria to evaluate the adhesiveness. "A": 5N / cm or more "B": 4N / cm or more and less than 5N / cm "C": 2N / cm or more and less than 4N / cm "D": Less than 2N / cm

[0190] [result] Table 1 below shows the characteristics and test results of the sheets for forming a thermally conductive layer in each of the examples and comparative examples. In the table, the "average particle size [μm]" column in the "inorganic substance" column indicates the average particle size (μm) of the inorganic substance (boron nitride) contained in the film of the produced sheet for forming a thermally conductive layer. The "Amount [%]" column in the "Inorganic Substance" column indicates the content (volume %) of the inorganic substance (boron nitride) relative to the total volume of the film of the produced sheet for forming a thermally conductive layer. The "Quantity [%]" column in the "Thermosetting component and curing accelerator" column indicates the total content (volume %) of the thermosetting component and the component derived from the curing accelerator relative to the total volume of the film of the produced sheet for forming a thermal conductive layer. In all of the Examples and Comparative Examples, A-1 (epoxy compound) and B-1 (phenol compound) were used as the thermosetting components, and TPP-MK was used as the curing accelerator. The "Solid content concentration (vol %)" column in the "Solvent" column indicates the solid content concentration (vol %) in the composition (film-forming composition) used in each Example or Comparative Example. In all Examples and Comparative Examples, CPO (cyclopentanone) was used as the solvent. The "Film state" column indicates whether the film of the produced sheet for forming a thermally conductive layer is in an A-stage, B-stage, or C-stage state. The column "Ra [μm]" indicates the arithmetic mean roughness Ra (μm) of the film of the prepared sheet for forming a thermally conductive layer. The "Coverage [%]" column in the "Adhesive Layer" column indicates the percentage (%) of the area of ​​the film that is covered by the adhesive layer (adhesive). The column "BA" indicates the value obtained by subtracting the value A (unit: μm) of the arithmetic mean roughness Ra from the value B (unit: %) of the coverage rate in the heat conductive layer-forming sheet.

[0191] [Table 1]

[0192] From the results shown in the table, it was confirmed that the problems of the present invention can be solved by using the sheet for forming a thermally conductive layer of the present invention. In particular, it was confirmed that when the arithmetic mean roughness Ra of the surface on the adhesive layer side of the film is 7.0 to 13.0 μm and the coverage is 55.0 to 80.0%, the thermal conductivity and adhesiveness of the thermal conductive layer are better balanced and excellent (see the results of Examples 1 to 6, etc.).

[0193] [Additional Example A] A sheet for forming a thermal conductive layer was produced in the same manner as in Example 1, except that the method shown in the above [Production of adhesive layer (production of sheet for forming a thermal conductive layer)] was replaced with the following procedure. That is, the adhesive was sprayed onto the release surface of a release-treated polyester film (PET75 6501 manufactured by Lintec Corporation, film thickness 75 μm) so that the coverage and film thickness of the adhesive layer ultimately placed on the film surface would be the same as in Example 1. The adhesive applied to the polyester film was dried at room temperature (25°C) to form an adhesive transfer layer. The polyester film was attached to a film similar to that in Example 1 with the adhesive transfer layer on the side where the adhesive transfer layer was present, and the adhesive transfer layer was transferred to the surface of the film, thereby placing an adhesive layer on the surface of the film. The polyester film was similarly laminated to the other side of the film, and adhesive layers were disposed on both surfaces of the film. It was confirmed that even when the polyester film was peeled off in this state, the adhesive layer (adhesive transfer layer) remained on the film side, and only the polyester film was removed. In this way, a laminate for forming a thermally conductive layer having a structure of "polyester film-sheet for forming a thermally conductive layer-polyester film" was obtained. Using the laminate for forming a thermally conductive layer, the thermal conductivity (W / m·k) and adhesiveness (copper foil peel strength) were measured in the same manner as described above, and it was confirmed that the results were similar to those of Example 1.

[0194] [Additional Example B] An adhesive was spray-applied onto the release surface of a release-treated polyester film (PET75 6501 manufactured by Lintec Corporation, film thickness 75 μm) so that the coverage and film thickness of the adhesive layer ultimately placed on the film surface would be the same as in Example 1. The adhesive applied to the polyester film was dried at room temperature (25°C) to form an adhesive layer. The same composition as used in Example 1 was applied to the surface of the polyester film on which the adhesive layer was present to form a coating film. Thereafter, the polyester film with the adhesive layer and coating was left at 120°C for 5 minutes to make the coating film into an A-stage film (A-stage product). As a result, the adhesive layer was disposed on the surface of the film (the interface of the film on the polyester film side), and a sheet for forming a thermally conductive layer was obtained. The arithmetic mean roughness Ra of the film in such a sheet for forming a thermal conductive layer was also similar to the arithmetic mean roughness Ra of the film in the sheet for forming a thermal conductive layer of Example 1. Furthermore, an adhesive layer similar to that formed in Example 1 was formed on the surface of the thermal conductive layer-forming sheet on the side on which the adhesive layer was not placed, using the same method as shown in [Preparation of adhesive layer (preparation of thermal conductive layer-forming sheet)]. In this way, a laminate for forming a thermally conductive layer having a structure of "polyester film-sheet for forming a thermally conductive layer-polyester film" was obtained. Using the laminate for forming a thermally conductive layer, the thermal conductivity (W / m·k) and adhesiveness (copper foil peel strength) were measured in the same manner as described above, and it was confirmed that the results were similar to those of Example 1. [Explanation of symbols]

[0195] 100 Film 120 Adhesive layer 140 Sheet for forming thermal conductive layer 160 Adherent 10. Sheet for forming thermally conductive layer 12 Film 14 Adhesive layer 16 Adhesive part 18 Adherent

Claims

1. a film formed using a composition containing an inorganic substance and a thermosetting compound; An adhesive layer disposed on a portion of the surface of the film, The film satisfies the following requirement 1: The sheet for forming a thermally conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A

2. The sheet for forming a thermal conductive layer according to claim 1, wherein A is 7.0 to 13.

0.

3. The sheet for forming a thermally conductive layer according to claim 1 or 2, wherein the inorganic material comprises aggregated boron nitride.

4. 4. The sheet for forming a thermally conductive layer according to claim 3, wherein the aggregated boron nitride has an average particle size of 20 [mu]m or more.

5. The sheet for forming a thermal conductive layer according to any one of claims 1 to 4, wherein the thermosetting compound includes an epoxy compound.

6. The sheet for forming a thermally conductive layer according to claim 5 , wherein the thermosetting compound includes a phenol compound.

7. a film forming step of forming a film using a composition containing an inorganic substance and a thermosetting compound; An adhesive layer forming step of disposing an adhesive layer on a part of the surface of the film, The film satisfies the following requirement 1: The method for producing a sheet for forming a thermal conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A

8. In the adhesive layer forming step, The method for producing a sheet for forming a thermal conductive layer according to claim 7 , wherein an adhesive is applied directly to the surface of the film, and the adhesive layer is disposed on the surface of the film.

9. In the adhesive layer forming step, An adhesive is applied to the surface of the release sheet to form an adhesive transfer layer, The method for producing a sheet for forming a thermal conductive layer according to claim 7, wherein the adhesive transfer layer formed on the surface of the release sheet is transferred to the surface of the film, and the adhesive layer is disposed on the surface of the film.

10. an adhesive layer forming step of applying an adhesive to a release sheet to form an adhesive layer; a film forming step of forming a film on the surface of the release sheet on which the adhesive layer is formed, using a composition containing an inorganic substance and a thermosetting compound, The film satisfies the following requirement 1: The method for producing a sheet for forming a thermal conductive layer, wherein the adhesive layer satisfies the following requirement 2. Requirement 1: When the arithmetic mean roughness Ra of the surface of the film on the adhesive layer side is A μm, the relationship of formula (1) is satisfied. Formula (1) 5.0≦A≦15.0 Requirement 2: When the coverage of the adhesive layer with respect to the surface of the film on which the adhesive layer is disposed is B%, the relationship of formula (2) is satisfied. Formula (2) 40.0+A≦B≦80.0+A

11. The method for producing a sheet for forming a thermal conductive layer according to any one of claims 8 to 10, wherein the adhesive is applied by any one of spray coating, screen printing, gravure printing, and inkjet printing.

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