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WO2024048396A1 - Graphite sheet, and method for producing same - Google Patents

Graphite sheet, and method for producing same Download PDF

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Publication number
WO2024048396A1
WO2024048396A1 PCT/JP2023/030358 JP2023030358W WO2024048396A1 WO 2024048396 A1 WO2024048396 A1 WO 2024048396A1 JP 2023030358 W JP2023030358 W JP 2023030358W WO 2024048396 A1 WO2024048396 A1 WO 2024048396A1
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WIPO (PCT)
Prior art keywords
graphite
graphite sheet
particles
thickness direction
sheet according
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PCT/JP2023/030358
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French (fr)
Japanese (ja)
Inventor
文武 糸瀬
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パナソニックＩｐマネジメント株式会社
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Publication of WO2024048396A1 publication Critical patent/WO2024048396A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/205—Preparation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon

Definitions

  • the present disclosure relates to a graphite sheet and a method for manufacturing a graphite sheet, and specifically relates to a graphite sheet having a plurality of graphite layers and a method for manufacturing the graphite sheet.
  • Patent Document 1 discloses a thermally conductive sheet using a graphite sheet obtained by thermally decomposing an organic film, in which a region other than the end surface of the graphite sheet has a surface direction that is aligned with each graphene layer constituting the graphite sheet.
  • a thermally conductive sheet is disclosed that is configured to be substantially perpendicular to the c-axis of the graphite layer, and a surface perpendicular to the c-axis of the graphene layer is exposed at the end surface of the graphite sheet.
  • the thermal conductivity in the plane direction of the graphite sheet is low due to the fact that the graphite layers are mostly arranged in the plane direction. While the thermal conductivity in the thickness direction is very high at about 2000 W/mK, the thermal conductivity in the thickness direction is low at about 5 W/mK, and the thermal resistance in the thickness direction is large.
  • An object of the present disclosure is to provide a graphite sheet and a method for manufacturing a graphite sheet that can reduce thermal resistance in the thickness direction.
  • a graphite sheet according to one embodiment of the present disclosure has a plurality of graphite layers.
  • a method for producing graphite according to one aspect of the present disclosure includes a first step, a second step, and a third step.
  • a solution or suspension containing graphene oxide and a surfactant is prepared.
  • a precursor film is formed using the solution or suspension.
  • the precursor film is heat-treated to obtain a graphite sheet having a plurality of graphite layers.
  • FIG. 1 is an electron micrograph of a cross section of the graphite sheet of Example 1.
  • FIG. 2 is an electron micrograph of a cross section of the graphite sheet of Example 6.
  • a graphite sheet can be placed between a heating element and a heat radiating element and tightened with a screw, etc., thereby compressing the graphite sheet and bringing it into close contact with the heating element and the heat radiating element, thereby transferring the heat generated by the heating element to the heat radiating element.
  • the graphite layer formed is mostly arranged in the plane direction, so the thermal resistance in the plane direction is very small.
  • the thermal resistance in the thickness direction which is the heat conduction direction, was large.
  • the inventors have repeatedly studied how to reduce the thermal resistance in the thickness direction by controlling the arrangement of the multiple graphite layers formed during the production of graphite sheets.
  • the present disclosure was completed based on the discovery that the thermal resistance in the thickness direction can be reduced by using a surfactant or by using a surfactant and graphite particles during manufacturing.
  • the graphite sheet of the first embodiment of the present disclosure has multiple graphite layers.
  • the graphite sheet of the second embodiment of the present disclosure further includes a plurality of graphite particles between and at least partially within the graphite layers.
  • the graphite sheet according to the present disclosure thermal resistance in the thickness direction can be reduced.
  • the reason why the graphite sheet according to the present disclosure achieves the above effects by having the above structure is not necessarily clear, it can be inferred as follows, for example.
  • the graphite layer formed is arranged not only in the in-plane direction, but also in a proportion of the graphite arranged in a direction that has a component perpendicular to the in-plane direction. It is thought that there will be more layers.
  • the arrangement of the graphite layer formed changes due to the interaction between the surfactant and a raw material such as graphene oxide.
  • the surfactant is thermally decomposed during the heat treatment to form the graphite sheet, and a portion of the thermally decomposed surfactant, such as a residue, contributes to bonding the graphite layers together.
  • the number of places where the graphite layers are bonded to each other increases in the thickness direction, so it is thought that the thermal resistance in the thickness direction becomes smaller.
  • the proportion of graphite layers arranged in a direction other than the plane direction increases.
  • the graphite layer is arranged in a direction having a thickness direction component in the vicinity of the graphite particles. As a result, the thermal resistance in the thickness direction of the graphite sheet can be reduced.
  • the method for manufacturing a graphite sheet according to the first embodiment of the present disclosure includes a first step, a second step, and a third step.
  • a solution or suspension containing graphene oxide and a surfactant is prepared.
  • a precursor film is formed using the solution or suspension.
  • the precursor film is heat treated to obtain a graphite sheet having a plurality of graphite layers.
  • the solution or suspension in the first step of the graphite sheet manufacturing method of the first embodiment further includes a plurality of graphite particles.
  • a graphite sheet with low thermal resistance in the thickness direction can be obtained by a simple method.
  • the graphite sheet of the first embodiment (hereinafter also referred to as graphite sheet (X)) has a plurality of graphite layers (hereinafter also referred to as graphite layer (A)). That is, the graphite sheet (X) is formed by laminating a plurality of graphite layers (A) in the thickness direction.
  • the “graphite layer” is a layer made of graphite (graphite) that constitutes a single cleavage plane.
  • the graphite layer usually includes one or more layers of graphene (a layer in which carbon atoms are arranged in a hexagonal honeycomb lattice, and is usually a single layer).
  • the average thickness of the graphite layer (A) is, for example, 0.001 ⁇ m or more and 20 ⁇ m or less, and preferably 0.01 ⁇ m or more and 10 ⁇ m or less.
  • the graphite layer (A) is preferably formed from graphene oxide, and more preferably formed from graphene oxide in the presence of a surfactant.
  • the graphite layer (A) is formed from graphene oxide mainly having a single-layer structure, and is also formed in the presence of a surfactant that can interact with the oxygen-containing groups of graphene oxide. Therefore, it is thought that the proportion of graphite sheets (X) arranged in the thickness direction increases, and as a result, the graphite sheet (X) can have a smaller thermal resistance in the thickness direction.
  • the graphite sheet (X) of the second embodiment includes a plurality of graphite layers (A) and a plurality of graphite particles (hereinafter also referred to as graphite particles (B)).
  • the plurality of graphite particles (B) are present between the graphite layers (A) and at least partially within the layers. That is, the graphite sheet (X) has a plurality of graphite particles (B) between and at least partially within the plurality of graphite layers (A) stacked in the thickness direction.
  • the graphite sheet (X) increases the proportion of graphite layers (A) arranged in a direction having a thickness direction component.
  • graphite layer The plurality of graphite layers (A) are the same as the plurality of graphite layers (A) in the first embodiment.
  • Graphite particles mean graphite particles. "Graphite” is one of the allotropes of carbon, and is also called graphite. However, the graphite particles (B) are different from the graphite layer (A).
  • graphite examples include natural graphite such as graphite stone and graphite minerals, artificial graphite (synthetic graphite) such as highly oriented pyrolytic graphite, and scaly graphite.
  • the graphite particles (B) preferably include particles of artificial graphite. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • Examples of the shape of the graphite particles (B) include flat shapes such as scales, scales, and flakes, and spherical shapes. It is preferable that the graphite particles (B) have at least one of a spherical shape and a scaly shape. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • the average particle diameter of the plurality of graphite particles (B) is preferably 0.1 ⁇ m or more and 100 ⁇ m or less. By setting the average particle size of the graphite particles (B) within the above range, the thermal resistance can be further reduced.
  • the average particle diameter of the graphite particles (B) is more preferably 1 ⁇ m or more and 60 ⁇ m or less, even more preferably 3 ⁇ m or more and 40 ⁇ m or less, and particularly preferably 10 ⁇ m or more and 30 ⁇ m or less.
  • the average particle diameter of graphite particles refers to the volume-based 50% cumulative distribution diameter (D50) of a plurality of (for example, 100) graphite particles.
  • the average particle size of the plurality of graphite particles (B) is preferably larger than the average thickness of the graphite layer (A).
  • the average particle size of the plurality of graphite particles (B) is preferably larger than the average thickness of the graphite layer (A).
  • the graphite layer (A) and at least a portion of the plurality of graphite particles (B) are bonded.
  • the graphite particles (B) are not discharged even when cut, and the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • bonds include covalent bonds between carbon atoms of the graphite layer (A) and carbon atoms of the plurality of graphite particles (B). It is thought that such a covalent bond is likely to be formed, for example, during the formation of the graphite sheet (X) due to the action of a part of the thermally decomposed surfactant such as a residue generated by heat treatment.
  • the distance between the plurality of graphite layers (A) is preferably smaller than the average particle diameter of the plurality of graphite particles (B). Further, the distance between the plurality of graphite layers (A) is preferably 25 ⁇ m or less. In such a case, the graphite layer (A) is arranged so as to avoid the graphite particles (B), and as a result, the graphite layer (A) is likely to be arranged in the thickness direction of the graphite sheet (X).
  • the average thickness of the graphite sheet (X) is, for example, 1 ⁇ m or more and 150 ⁇ m or less, preferably 10 ⁇ m or more and 120 ⁇ m or less, and more preferably 20 ⁇ m or more and 100 ⁇ m or less.
  • a portion of the graphite layer (A) extends in the plane direction of the graphite sheet (X), and in the vicinity of the plurality of graphite particles (B), at least a portion of the graphite layer (A) extends in the plane direction of the graphite sheet (X). Preferably, it extends in the thickness direction.
  • the proportion of the formed graphite layer (A) in the direction having a thickness direction component is higher in the vicinity thereof. It is thought that it will become larger. In this way, by having the graphite layer (A) that has a component in the thickness direction and is oriented diagonally, the thermal resistance in the thickness direction of the graphite sheet (X) can be efficiently reduced. Can be done.
  • the compression rate of the graphite sheet (X) when compressed at 200 kPa in the thickness direction is preferably 55% or more. By increasing the compressibility of the graphite sheet (X), the thermal resistance in the thickness direction can be further reduced.
  • the compression rate is more preferably 60% or more, and even more preferably 65% or more.
  • the compression ratio is, for example, 75% or less. Note that the compression ratio is the value of (T0-T1)/T0 expressed as a percentage, where T0 is the initial thickness and T1 is the thickness when the pressure is released after applying a pressure of 200 kPa.
  • the thermal resistance in the thickness direction of the graphite sheet (X) when the graphite sheet (X) is compressed in the thickness direction at 200 kPa is preferably 0.4 Kcm 2 /W or less. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be made sufficiently small.
  • the thermal resistance in the thickness direction of the graphite sheet (X) is more preferably at most 0.27 Kcm 2 /W, even more preferably at most 0.24 Kcm 2 /W, and even more preferably at most 0.19 Kcm 2 /W. It is particularly preferable that there be.
  • the method for manufacturing the graphite sheet (X) of the first embodiment includes a first step, a second step, and a third step, as shown below. Each step will be explained below.
  • Graphene oxide is graphene (which mainly includes compounds with a structure in which carbon atoms are arranged in a hexagonal honeycomb lattice) modified with oxygen-containing groups such as carboxyl groups, carbonyl groups, and hydroxyl groups. It is.
  • a surfactant is a substance that acts on the interface of a substance to change its properties, and usually has a structure that includes both a hydrophilic part and a hydrophobic part within the molecule.
  • the surfactant examples include anionic surfactants, ionic surfactants such as cationic surfactants, and nonionic surfactants.
  • the surfactant preferably includes an ionic surfactant, and more preferably an anionic surfactant.
  • anionic surfactants include sulfonic acids or salts thereof, carboxylic acids or salts thereof, and the like.
  • sulfonic acid salts and carboxylic acid salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkaline earth metal salts such as magnesium salts, calcium salts, and barium salts; Examples include amine salts such as triethanolamine salts.
  • alkali metal salts are preferred, at least one of sodium salts and potassium salts is more preferred, and sodium salts are even more preferred.
  • sulfonic acid examples include aliphatic sulfonic acid and aromatic sulfonic acid.
  • aliphatic sulfonic acids examples include octane sulfonic acid and dodecyl sulfonic acid.
  • salts of aliphatic sulfonic acids include sodium octanesulfonate and sodium dodecylsulfonate.
  • aromatic sulfonic acid examples include aromatic sulfonic acids having an alkyl group such as dodecylbenzenesulfonic acid, and aromatic sulfonic acids not having an alkyl group such as naphthalenetrisulfonic acid.
  • salts of aromatic sulfonic acids include salts of aromatic sulfonic acids having an alkyl group such as sodium dodecylbenzenesulfonate, salts of aromatic sulfonic acids having no alkyl group such as trisodium naphthalene trisulfonate, etc. Can be mentioned.
  • carboxylic acid examples include tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), and the like.
  • carboxylic acid salts include sodium myristate, sodium palmitate, and sodium stearate.
  • the anionic surfactant preferably contains at least one of aliphatic sulfonic acids and salts thereof, and aromatic sulfonic acids and salts thereof, and at least one of aliphatic sulfonic acids and salts thereof. It is more preferable to include one or the other. In this case, the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be more effectively reduced.
  • the aromatic sulfonic acid and its salts preferably include aromatic sulfonic acids and salts thereof having an alkyl group, and more preferably include salts of aromatic sulfonic acids having an alkyl group.
  • the surfactant since the surfactant has an alkyl group bonded to an aromatic ring, it is possible to more effectively reduce the thermal resistance in the thickness direction of the obtained graphite sheet (X).
  • alkyl group examples include linear alkyl groups such as n-octyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-icosyl group, isooctyl group, isododecyl group, etc.
  • Examples include branched alkyl groups.
  • the alkyl group is preferably a linear alkyl group, more preferably an n-dodecyl group.
  • the length of the carbon chain of the alkyl group is preferably 9 or more and 17 or less. When the length of the carbon chain is 9 or more, the thermal resistance of the graphite sheet (X) can be further reduced. When the length of the carbon chain is 17 or less, the graphene oxide dispersion can be made more stable.
  • the length of the carbon chain of the alkyl group is more preferably 10 or more and 14 or less, most preferably 12. "Length of carbon chain of alkyl group" refers to the number of carbon atoms in the longest carbon chain in the alkyl group.
  • the solution or suspension in the first step may be prepared by, for example, adding an aqueous solution of graphene oxide to an aqueous solution of a surfactant, and stirring the resulting mixture using, for example, a stirring defoaming machine. Can be done.
  • a precursor film is formed using the solution or suspension prepared in the first step.
  • the precursor film in the second step is produced by, for example, applying the solution or suspension obtained in the first step onto a base material such as PET to a predetermined thickness using a device such as a coater, and then drying it. It can be formed by, for example.
  • the coating thickness is, for example, 0.1 mm or more and 3 mm or less.
  • the drying temperature is, for example, 30°C or higher and 80°C or lower.
  • the precursor film formed in the second step is heat-treated to obtain a graphite sheet (X) having a plurality of graphite layers (A).
  • the heat treatment in the third step can be performed, for example, by firing the precursor film formed in the second step. This firing is usually performed by applying a load to the precursor film.
  • the temperature of this firing is, for example, 2000°C or more and 3000°C or less, preferably 2500°C or more and 2800°C or less.
  • the graphite sheet manufacturing method of the second embodiment differs from the graphite sheet manufacturing method of the first embodiment described above in that, in the first step, a plurality of graphite particles (B) are added in addition to graphene oxide and a surfactant. They differ in that they further contain solutions or suspensions, but are otherwise similar.
  • a solution or suspension containing graphene oxide, a surfactant, and a plurality of graphite particles (B) is prepared.
  • the graphene oxide and surfactant are the same as those used in the graphite sheet manufacturing method of the first embodiment.
  • the plurality of graphite particles (B) have at least one of a spherical shape and a scaly shape.
  • the plurality of graphite particles (B) include particles of artificial graphite.
  • the average particle diameter of the plurality of graphite particles (B) is preferably 10 ⁇ m or more and 100 ⁇ m or less. It is thought that by setting the average particle size of the graphite particles (B) within the above range, in the graphite sheet (X), the proportion of the graphite layer (A) arranged in a direction having a thickness direction component increases. As a result, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • the average particle diameter of the graphite particles (B) is more preferably 15 ⁇ m or more and 60 ⁇ m or less, and even more preferably 18 ⁇ m or more and 40 ⁇ m or less.
  • the weight ratio of the plurality of graphite particles (B) is preferably 1% or more and 70% or less with respect to the solid content of graphene oxide and the total amount of the plurality of graphite particles. In this case, a strong graphite sheet (X) with low compression ratio can be obtained.
  • the weight ratio is more preferably 10% or more and 60% or less, and even more preferably 25% or more and 45% or less.
  • the graphite sheet (X) obtained in the third step preferably has a plurality of graphite particles (B) between the graphite layers (A) and at least partially within the layers.
  • a graphite sheet was manufactured by the following procedure. [First step] (Preparation of solution or suspension) (raw materials) The raw materials used for preparing the solution or suspension are shown below.
  • ⁇ Graphene oxide graphene oxide aqueous dispersion (solid content concentration 1.8% by weight)
  • ⁇ Graphite particles MAG-4 (average particle size 3.9 ⁇ m), SGS20 (average particle size 20 ⁇ m), G3 (average particle size 38 ⁇ m) manufactured by Fuji Graphite Industries Co., Ltd.
  • SDBS Sodium dodecylbenzenesulfonate
  • SDS Sodium dodecylsulfonate
  • SO Sodium octanesulfonate
  • TNTS Trisodium naphthalene trisulfonate
  • Example 1 0.45 g of artificial graphite powder with an average particle size of 20 ⁇ m was placed in a small bottle, and 12 g of an aqueous solution (1.5% by weight) of sodium dodecylbenzenesulfonate (SDBS) was added thereto and stirred. Next, 45 g of graphene oxide aqueous dispersion (1.8% by weight) was added to this and stirred with a stirring defoamer to prepare a solution or suspension. (Examples 2 to 5) Example 1 except that graphite particle powder having the average particle diameter shown in Table 1 below was used in an amount to give the weight % shown in Table 1, and a surfactant of the type and weight % shown in Table 1 was used.
  • SDBS sodium dodecylbenzenesulfonate
  • a solution or suspension was prepared in the same manner as above.
  • Example 6 A solution or suspension was prepared in the same manner as in Example 1, except that graphite particles were not blended.
  • Examples 7 to 9 A solution or suspension was prepared in the same manner as in Example 6, except that the types and weight percentages of surfactants shown in Table 1 were used.
  • Comparative example 1 45 g of graphene oxide aqueous dispersion (1.8% by weight) was placed in a small bottle and stirred with a stirring defoamer to prepare a solution or suspension.
  • FIG. 1 An electron micrograph of a cross section of the graphite sheet of Example 1 is shown in FIG. 1, and an electron micrograph of a cross section of the graphite sheet of Example 6 is shown in FIG.
  • the proportion of graphite layers arranged in a direction having a thickness direction component is high.
  • FIG. 1 it can be seen that the tendency for alignment in this direction is high in the vicinity of graphite particles.
  • Thermal conductivity in the thickness direction From the measured thermal resistance in the thickness direction and the measured value of the average thickness after compression, the thermal conductivity in the thickness direction was calculated using the following formula (2).
  • Thermal conductivity in the thickness direction (W/mK) Average thickness after compression ( ⁇ m)/(Thermal resistance in thickness direction (W/) x 100) ...(2)
  • [Material thermal conductivity] The relationship between the pressing force in the thickness direction and the thermal resistance in the thickness direction was measured.
  • the pressing force was set at six points: 50 kPa, 100 kPa, 200 kPa, 300 kPa, 500 kPa, and 600 kPa, and the thermal resistance in the thickness direction was measured for each case.
  • the measured values of thermal resistance for each pressing force were plotted, the slope thereof was determined, and the reciprocal of this slope was taken as the material thermal conductivity.
  • the graphite sheet (X) according to the first aspect of the present disclosure has a plurality of graphite layers (A).
  • the thermal resistance in the thickness direction of the graphite sheet (X) can be reduced.
  • a plurality of graphite particles (B) are further included between the graphite layers (A) and at least partially within the layers.
  • the graphite particles are contained while maintaining the structure of the graphite layer (A), thereby increasing the proportion of the graphite layer (A) arranged in a direction having a thickness direction component. It is considered possible to reduce the thermal resistance in the thickness direction of the graphite sheet (X).
  • At least a portion of the graphite layer (A) and at least a portion of the plurality of graphite particles (B) are combined.
  • the graphite particles (B) are not discharged even when cut, and the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • the average particle size of the plurality of graphite particles (B) is larger than the average thickness of the graphite layer (A).
  • the graphite layer (B) having an average particle diameter larger than the average thickness of the graphite layer (A)
  • the proportion of A) can be increased, and as a result, the thermal resistance in the thickness direction of the graphite sheet (X) can be made smaller.
  • a part of the graphite layer (A) extends in the plane direction of the graphite sheet (X), and a plurality of graphite particles ( In the vicinity of B), at least a portion of the graphite layer (A) extends in the thickness direction of the graphite sheet (X).
  • the graphite layer (A) has a component in the thickness direction of the graphite sheet (X) in the vicinity of the graphite particles (B) and is oriented obliquely, so that the graphite The thermal resistance in the thickness direction of the sheet (X) can be efficiently reduced.
  • the compression rate of the graphite sheet (X) when compressed at 200 kPa in the thickness direction is 55% or more. It is.
  • the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
  • thermal resistance in the thickness direction of the graphite sheet (X) when the graphite sheet (X) is compressed at 200 kPa in the thickness direction is 0.1 Kcm 2 /W or more and 0.4 Kcm 2 /W or less.
  • the thermal resistance in the thickness direction of the graphite sheet (X) can be made sufficiently small.
  • the graphite layer (A) is formed from graphene oxide.
  • the graphite layer (A) from graphene oxide, it is possible to further reduce the thermal resistance in the thickness direction of the graphite sheet (X).
  • the method for manufacturing a graphite sheet (X) according to the ninth aspect of the present disclosure includes a first step, a second step, and a third step.
  • a solution or suspension containing graphene oxide and a surfactant is prepared.
  • a precursor film is formed using the solution or suspension.
  • the precursor film is heat-treated to obtain a graphite sheet (X) having a plurality of graphite layers (A).
  • a graphite sheet (X) with low thermal resistance in the thickness direction can be obtained by a simple method.
  • the solution or suspension in the first step further contains a plurality of graphite particles (B).
  • the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be further reduced.
  • a plurality of graphite particles (B) are added between and at least in part of the graphite layer (A).
  • the content of the graphite particles (B) in the obtained graphite sheet (X) increases the proportion of the graphite layer (A) arranged in the direction having the thickness direction component. It is thought that it is possible to increase the thermal resistance in the thickness direction of the graphite sheet (X).
  • the plurality of graphite particles (B) are at least one of spherical and scaly.
  • the thermal resistance in the thickness direction of the graphite sheet (X) obtained can be further reduced.
  • the plurality of graphite particles (B) include particles of artificial graphite.
  • the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be made smaller.
  • the average particle size of the plurality of graphite particles (B) is 10 ⁇ m or more and 100 ⁇ m or less.
  • the fourteenth aspect by using graphite particles (B) having an average particle size within the above range, the proportion of the graphite layer (A) arranged in a direction having a thickness direction component is increased. As a result, the thermal resistance of the graphite sheet (X) obtained can be further reduced.
  • the surfactant includes an anionic surfactant.
  • the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be more effectively reduced.
  • the anionic surfactant contains at least one of an aliphatic sulfonic acid and a salt thereof, and an aromatic sulfonic acid and a salt thereof.
  • the thermal resistance of the obtained graphite sheet (X) can be more effectively reduced.
  • the aromatic sulfonic acid and its salt include an aromatic sulfonic acid and its salt having an alkyl group.
  • the thermal resistance of the obtained graphite sheet (X) can be more effectively improved. Can be made smaller.
  • the solid content of graphene oxide and the total amount of the plurality of graphite particles (B) in the solution or suspension in the first step, is 1% or more and 70% or less.
  • the eighteenth aspect by setting the ratio of graphite particles (B) to the total of graphene oxide and graphite particles (B) within the above range, it is possible to obtain a strong graphite sheet (X) with a low compressibility. can.

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Abstract

The present disclosure addresses the problem of providing a graphite sheet of which the thermal resistance in the thickness direction can be lowered. The graphite sheet has a plurality of graphite layers.

Description

グラファイトシート及びその製造方法Graphite sheet and its manufacturing method
　本開示は、グラファイトシート及びグラファイトシートの製造方法に関し、詳しくは、複数のグラファイト層を有するグラファイトシート及びこのグラファイトシートの製造方法に関する。 The present disclosure relates to a graphite sheet and a method for manufacturing a graphite sheet, and specifically relates to a graphite sheet having a plurality of graphite layers and a method for manufacturing the graphite sheet.
　近年電動機を走行用の主駆動源や補助駆動源として用いる電気自動車やハイブリッド車等が増加している。これらを制御するインバータにおいて、絶縁ゲートバイポーラトランジスタ（Ｉｎｓｕｌａｔｅｄ　Ｇａｔｅ　Ｂｉｐｏｌａｒ　Ｔｒａｎｓｉｓｔｏｒ（ＩＧＢＴ））等のパワーモジュールなどは発熱が大きい。そのため、このような発熱体は、駆動時に発生する熱を逃がすために、ヒートシンク等の放熱体に取り付けて使用される。この場合、発熱体から放熱体へスムースに熱を伝えるために、発熱体と放熱体との間に熱伝導シートを挟むことが行われ、この熱伝導シートとして、グラファイトシートが用いられている。 In recent years, there has been an increase in the number of electric vehicles, hybrid vehicles, etc. that use electric motors as the main drive source or auxiliary drive source for driving. In the inverter that controls these, power modules such as insulated gate bipolar transistors (IGBTs) generate a large amount of heat. Therefore, such a heating element is used by being attached to a heat sink such as a heat sink in order to release the heat generated during driving. In this case, in order to smoothly transfer heat from the heat generating element to the heat radiating element, a heat conductive sheet is sandwiched between the heat generating element and the heat radiating element, and a graphite sheet is used as this heat conductive sheet.
　特許文献１には、有機フィルムを熱分解して得られるグラファイトシートを用いた熱伝導シートであって、前記グラファイトシートの端面以外の領域は、その面方向が前記グラファイトシートを構成する各グラフェン層（グラファイト層）のｃ軸とほぼ垂直となるように構成されており、前記グラファイトシートの端面には前記グラフェン層のｃ軸と垂直な面が露出している熱伝導シートが開示されている。 Patent Document 1 discloses a thermally conductive sheet using a graphite sheet obtained by thermally decomposing an organic film, in which a region other than the end surface of the graphite sheet has a surface direction that is aligned with each graphene layer constituting the graphite sheet. A thermally conductive sheet is disclosed that is configured to be substantially perpendicular to the c-axis of the graphite layer, and a surface perpendicular to the c-axis of the graphene layer is exposed at the end surface of the graphite sheet.
　しかし、特許文献１に記載されているような有機フィルムを熱分解して得られるグラファイトシートは、グラファイト層がほとんど面方向に配列することに起因して、グラファイトシートの面方向における熱伝導率は２０００Ｗ／ｍＫ程度と非常に高い一方、厚さ方向における熱伝導率は５Ｗ／ｍＫ程度と低い値であり、厚さ方向における熱抵抗は大きくなっている。 However, in the graphite sheet obtained by thermally decomposing an organic film as described in Patent Document 1, the thermal conductivity in the plane direction of the graphite sheet is low due to the fact that the graphite layers are mostly arranged in the plane direction. While the thermal conductivity in the thickness direction is very high at about 2000 W/mK, the thermal conductivity in the thickness direction is low at about 5 W/mK, and the thermal resistance in the thickness direction is large.
特開２０１３－２２２９１８号公報JP2013-222918A
　本開示の課題は、厚さ方向の熱抵抗を小さくすることができるグラファイトシート及びグラファイトシートの製造方法を提供することである。 An object of the present disclosure is to provide a graphite sheet and a method for manufacturing a graphite sheet that can reduce thermal resistance in the thickness direction.
　本開示の一態様に係るグラファイトシートは、複数のグラファイト層を有する。 A graphite sheet according to one embodiment of the present disclosure has a plurality of graphite layers.
　本開示の一態様に係るグラファイトの製造方法は、第１工程と、第２工程と、第３工程とを備える。前記第１工程では、酸化グラフェンと、界面活性剤とを含む溶液又は懸濁液を準備する。前記第２工程では、前記溶液又は懸濁液を用いて、前駆体フィルムを形成する。前記第３工程では、前記前駆体フィルムを熱処理して、複数のグラファイト層を有するグラファイトシートを得る。 A method for producing graphite according to one aspect of the present disclosure includes a first step, a second step, and a third step. In the first step, a solution or suspension containing graphene oxide and a surfactant is prepared. In the second step, a precursor film is formed using the solution or suspension. In the third step, the precursor film is heat-treated to obtain a graphite sheet having a plurality of graphite layers.
図１は、実施例１のグラファイトシートの断面の電子顕微鏡写真である。FIG. 1 is an electron micrograph of a cross section of the graphite sheet of Example 1. 図２は、実施例６のグラファイトシートの断面の電子顕微鏡写真である。FIG. 2 is an electron micrograph of a cross section of the graphite sheet of Example 6.
１．概要
　以下、本開示の実施形態におけるグラファイトシート及びグラファイトシートの製造方法について説明する。なお、以下の実施形態は、本開示の様々な実施形態の一つに過ぎない。以下の実施形態は、本開示の目的を達成できれば、設計に応じて種々の変更が可能である。 1. Overview Hereinafter, a graphite sheet and a method for manufacturing a graphite sheet in an embodiment of the present disclosure will be described. Note that the following embodiment is only one of various embodiments of the present disclosure. The following embodiments can be modified in various ways depending on the design, as long as the objective of the present disclosure can be achieved.
　グラファイトシートは、例えば発熱体と放熱体との間に挟んで、ネジ等で締め付けることにより、グラファイトシートを圧縮しながら発熱体及び放熱体に密着させて、発熱体で発生した熱を放熱体にスムースに伝える熱伝導シートとして用いられる。グラファイトシートは、有機フィルムを焼成して作製する場合、形成されるグラファイト層がほとんど面方向に配列することに起因して、面方向における熱抵抗は非常に小さいものの、熱伝導シートとして用いる場合の熱伝導方向である厚さ方向における熱抵抗は大きいものになっていた。 For example, a graphite sheet can be placed between a heating element and a heat radiating element and tightened with a screw, etc., thereby compressing the graphite sheet and bringing it into close contact with the heating element and the heat radiating element, thereby transferring the heat generated by the heating element to the heat radiating element. Used as a heat conductive sheet that transmits heat smoothly. When a graphite sheet is produced by firing an organic film, the graphite layer formed is mostly arranged in the plane direction, so the thermal resistance in the plane direction is very small. The thermal resistance in the thickness direction, which is the heat conduction direction, was large.
　これに対し、発明者らは、グラファイトシートの製造の際に、形成される複数のグラファイト層の配列を制御することにより、厚さ方向における熱抵抗を小さくすることについて検討を重ね、グラファイトシートの製造の際に、界面活性剤を用いることにより、又は界面活性剤及び黒鉛粒子を用いることにより、厚さ方向における熱抵抗を小さくすることができることを見出し、本開示を完成させた。 In response, the inventors have repeatedly studied how to reduce the thermal resistance in the thickness direction by controlling the arrangement of the multiple graphite layers formed during the production of graphite sheets. The present disclosure was completed based on the discovery that the thermal resistance in the thickness direction can be reduced by using a surfactant or by using a surfactant and graphite particles during manufacturing.
　本開示の第１実施形態のグラファイトシートは、複数のグラファイト層を有する。
　本開示の第２実施形態のグラファイトシートは、第１実施形態のグラファイトシートにおける複数のグラファイト層に加えて、前記グラファイト層の層間及び層内の少なくとも一部に、複数の黒鉛粒子をさらに有する。 The graphite sheet of the first embodiment of the present disclosure has multiple graphite layers.
In addition to the plurality of graphite layers in the graphite sheet of the first embodiment, the graphite sheet of the second embodiment of the present disclosure further includes a plurality of graphite particles between and at least partially within the graphite layers.
　本開示に係るグラファイトシートによれば、厚さ方向における熱抵抗を小さくすることができる。本開示に係るグラファイトシートが前記構成を備えることで、前記効果を奏する理由については必ずしも明確ではないが、例えば以下のように推察することができる。すなわち、グラファイトシートの形成の際に、界面活性剤を存在させることにより、形成されるグラファイト層の配列が面方向だけでなく、面方向と垂直な方向の成分を有する方向の配列の割合のグラファイト層が多くなると考えられる。界面活性剤の作用については、例えば酸化グラフェン等の原料と界面活性剤との相互作用により、形成されるグラファイト層の配列が変わってくること等が考えられる。加えて、界面活性剤は、グラファイトシートを形成する熱処理の際に熱分解し、残渣等の熱分解した界面活性剤の一部が、グラファイト層同士を結合させることに寄与すると考えられる。その結果、厚さ方向にグラファイト層同士が結合している箇所が多くなるため、厚さ方向の熱抵抗が小さくなると考えられる。また、グラファイトシートの形成の際に、界面活性剤と共に黒鉛粒子をさらに存在させることにより、面方向以外の配列のグラファイト層の割合がより多くなると考えられる。黒鉛粒子の作用については、例えば黒鉛粒子の存在により、黒鉛粒子の近傍において、グラファイト層が厚さ方向の成分を有する方向に配列すること等が考えられる。これらの結果、グラファイトシートの厚さ方向における熱抵抗を小さくすることができる。 According to the graphite sheet according to the present disclosure, thermal resistance in the thickness direction can be reduced. Although the reason why the graphite sheet according to the present disclosure achieves the above effects by having the above structure is not necessarily clear, it can be inferred as follows, for example. In other words, by having a surfactant present during the formation of a graphite sheet, the graphite layer formed is arranged not only in the in-plane direction, but also in a proportion of the graphite arranged in a direction that has a component perpendicular to the in-plane direction. It is thought that there will be more layers. Regarding the action of the surfactant, it is thought that the arrangement of the graphite layer formed changes due to the interaction between the surfactant and a raw material such as graphene oxide. In addition, it is believed that the surfactant is thermally decomposed during the heat treatment to form the graphite sheet, and a portion of the thermally decomposed surfactant, such as a residue, contributes to bonding the graphite layers together. As a result, the number of places where the graphite layers are bonded to each other increases in the thickness direction, so it is thought that the thermal resistance in the thickness direction becomes smaller. Furthermore, it is considered that by further making graphite particles exist together with a surfactant during the formation of a graphite sheet, the proportion of graphite layers arranged in a direction other than the plane direction increases. Regarding the effect of the graphite particles, for example, due to the presence of the graphite particles, it is possible that the graphite layer is arranged in a direction having a thickness direction component in the vicinity of the graphite particles. As a result, the thermal resistance in the thickness direction of the graphite sheet can be reduced.
　本開示の第１実施形態のグラファイトシートの製造方法は、第１工程と、第２工程と、第３工程とを備える。第１工程では、酸化グラフェンと、界面活性剤とを含む溶液又は懸濁液を準備する。第２工程では、前記溶液又は懸濁液を用いて、前駆体フィルムを形成する。第３工程では、前記前駆体フィルムを熱処理して、複数のグラファイト層を有するグラファイトシートを得る。
　本開示の第２実施形態のグラファイトシートの製造方法は、第１実施形態のグラファイトシートの製造方法の第１工程における前記溶液又は懸濁液が、複数の黒鉛粒子をさらに含む。 The method for manufacturing a graphite sheet according to the first embodiment of the present disclosure includes a first step, a second step, and a third step. In the first step, a solution or suspension containing graphene oxide and a surfactant is prepared. In the second step, a precursor film is formed using the solution or suspension. In the third step, the precursor film is heat treated to obtain a graphite sheet having a plurality of graphite layers.
In the graphite sheet manufacturing method of the second embodiment of the present disclosure, the solution or suspension in the first step of the graphite sheet manufacturing method of the first embodiment further includes a plurality of graphite particles.
　本開示に係るグラファイトシートの製造方法によれば、厚さ方向における熱抵抗が小さいグラファイトシートを簡便な方法で得ることができる。 According to the method for manufacturing a graphite sheet according to the present disclosure, a graphite sheet with low thermal resistance in the thickness direction can be obtained by a simple method.
　以上のように、本開示によれば、厚さ方向における熱抵抗を小さくすることができるグラファイトシート及びグラファイトシートの製造方法を提供することができる。 As described above, according to the present disclosure, it is possible to provide a graphite sheet and a method for manufacturing a graphite sheet that can reduce thermal resistance in the thickness direction.
２．詳細
＜グラファイトシート＞
［第１実施形態］
　第１実施形態のグラファイトシート（以下、グラファイトシート（Ｘ）ともいう）は、複数のグラファイト層（以下、グラファイト層（Ａ）ともいう）を有している。すなわち、グラファイトシート（Ｘ）は、複数のグラファイト層（Ａ）が厚さ方向に積層されたものである。 2. Details <Graphite sheet>
[First embodiment]
The graphite sheet of the first embodiment (hereinafter also referred to as graphite sheet (X)) has a plurality of graphite layers (hereinafter also referred to as graphite layer (A)). That is, the graphite sheet (X) is formed by laminating a plurality of graphite layers (A) in the thickness direction.
（グラファイト層）
　「グラファイト層」とは、単一の劈開面を構成するグラファイト（黒鉛）からなる層である。グラファイト層は、通常、１又は複数のグラフェンの層（炭素原子が六角形のハニカム格子状に配置された層であって、通常、単層である）を含んでいる。 (graphite layer)
The "graphite layer" is a layer made of graphite (graphite) that constitutes a single cleavage plane. The graphite layer usually includes one or more layers of graphene (a layer in which carbon atoms are arranged in a hexagonal honeycomb lattice, and is usually a single layer).
　グラファイト層（Ａ）の平均厚さは、例えば０．００１μｍ以上２０μｍ以下であり、０．０１μｍ以上１０μｍ以下であることが好ましい。 The average thickness of the graphite layer (A) is, for example, 0.001 μm or more and 20 μm or less, and preferably 0.01 μm or more and 10 μm or less.
　グラファイト層（Ａ）は、酸化グラフェンから形成されたものであることが好ましく、界面活性剤の存在下で、酸化グラフェンから形成されたものであることがより好ましい。グラファイト層（Ａ）は、単層構造を主とする酸化グラフェンから形成されることで、また、酸化グラフェンの酸素含有基等と相互作用することができる界面活性剤の存在下で形成されることで、形成されるグラファイトシート（Ｘ）の厚さ方向に配列する割合がより多くなると考えられ、その結果、グラファイトシート（Ｘ）は、厚さ方向における熱抵抗をより小さくすることができる。 The graphite layer (A) is preferably formed from graphene oxide, and more preferably formed from graphene oxide in the presence of a surfactant. The graphite layer (A) is formed from graphene oxide mainly having a single-layer structure, and is also formed in the presence of a surfactant that can interact with the oxygen-containing groups of graphene oxide. Therefore, it is thought that the proportion of graphite sheets (X) arranged in the thickness direction increases, and as a result, the graphite sheet (X) can have a smaller thermal resistance in the thickness direction.
［第２実施形態］
　第２実施形態のグラファイトシート（Ｘ）は、複数のグラファイト層（Ａ）と、複数の黒鉛粒子（以下、黒鉛粒子（Ｂ）ともいう）とを有している。複数の黒鉛粒子（Ｂ）は、グラファイト層（Ａ）の層間及び層内の少なくとも一部に存在している。すなわち、グラファイトシート（Ｘ）は、厚さ方向に積層された複数のグラファイト層（Ａ）の層間及び層内の少なくとも一部に、複数の黒鉛粒子（Ｂ）を有している。 [Second embodiment]
The graphite sheet (X) of the second embodiment includes a plurality of graphite layers (A) and a plurality of graphite particles (hereinafter also referred to as graphite particles (B)). The plurality of graphite particles (B) are present between the graphite layers (A) and at least partially within the layers. That is, the graphite sheet (X) has a plurality of graphite particles (B) between and at least partially within the plurality of graphite layers (A) stacked in the thickness direction.
　グラファイトシート（Ｘ）は、複数の黒鉛粒子（Ｂ）をさらに含むことで、グラファイト層（Ａ）が厚さ方向の成分を有する方向に配列する割合がより多くなると考えられる。 It is thought that by further including a plurality of graphite particles (B), the graphite sheet (X) increases the proportion of graphite layers (A) arranged in a direction having a thickness direction component.
（グラファイト層）
　複数のグラファイト層（Ａ）は、第１実施形態における複数のグラファイト層（Ａ）と同様である。 (graphite layer)
The plurality of graphite layers (A) are the same as the plurality of graphite layers (A) in the first embodiment.
（黒鉛粒子）
　黒鉛粒子（Ｂ）は、黒鉛の粒子を意味する。「黒鉛」とは、炭素の同素体の１つで、グラファイトともいう。但し、黒鉛粒子（Ｂ）は、グラファイト層（Ａ）とは異なる。 (graphite particles)
Graphite particles (B) mean graphite particles. "Graphite" is one of the allotropes of carbon, and is also called graphite. However, the graphite particles (B) are different from the graphite layer (A).
　黒鉛としては、例えば黒鉛石、黒鉛鉱物等の天然黒鉛、高配向熱分解黒鉛、鱗状黒鉛等の人造黒鉛（合成黒鉛）などが挙げられる。黒鉛粒子（Ｂ）としては、人造黒鉛の粒子を含むことが好ましい。この場合、グラファイトシート（Ｘ）の厚さ方向の熱抵抗をより小さくすることができる。 Examples of graphite include natural graphite such as graphite stone and graphite minerals, artificial graphite (synthetic graphite) such as highly oriented pyrolytic graphite, and scaly graphite. The graphite particles (B) preferably include particles of artificial graphite. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
　黒鉛粒子（Ｂ）の形状としては、例えば鱗片状、鱗状、薄片状等の扁平形状、球状などが挙げられる。黒鉛粒子（Ｂ）の形状は、球状及び鱗片状の少なくとも一方であることが好ましい。この場合、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 Examples of the shape of the graphite particles (B) include flat shapes such as scales, scales, and flakes, and spherical shapes. It is preferable that the graphite particles (B) have at least one of a spherical shape and a scaly shape. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
　複数の黒鉛粒子（Ｂ）の平均粒径は、０．１μｍ以上１００μｍ以下であることが好ましい。黒鉛粒子（Ｂ）の平均粒径を前記範囲とすることで、熱抵抗をより小さくすることができる。黒鉛粒子（Ｂ）の平均粒径は、１μｍ以上６０μｍ以下であることがより好ましく、３μｍ以上４０μｍ以下であることがさらに好ましく、１０μｍ以上３０μｍ以下であることが特に好ましい。黒鉛粒子の平均粒径とは、複数（例えば１００個）の黒鉛粒子における体積基準の５０％累積分布径（Ｄ５０）をいう。 The average particle diameter of the plurality of graphite particles (B) is preferably 0.1 μm or more and 100 μm or less. By setting the average particle size of the graphite particles (B) within the above range, the thermal resistance can be further reduced. The average particle diameter of the graphite particles (B) is more preferably 1 μm or more and 60 μm or less, even more preferably 3 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less. The average particle diameter of graphite particles refers to the volume-based 50% cumulative distribution diameter (D50) of a plurality of (for example, 100) graphite particles.
　複数の黒鉛粒子（Ｂ）の平均粒径は、グラファイト層（Ａ）の平均厚さよりも大きいことが好ましい。このような平均粒径の複数の黒鉛粒子（Ｂ）を用いることにより、厚さ方向の成分を有する方向に配列するグラファイト層（Ａ）の割合がより多くなり、その結果、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 The average particle size of the plurality of graphite particles (B) is preferably larger than the average thickness of the graphite layer (A). By using a plurality of graphite particles (B) having such an average particle diameter, the proportion of the graphite layer (A) arranged in a direction having a thickness direction component increases, and as a result, the graphite sheet (X) Thermal resistance in the thickness direction can be further reduced.
　グラファイト層（Ａ）の少なくとも一部と、複数の黒鉛粒子（Ｂ）の少なくとも一部とが結合していることが好ましい。この場合、切断したときでも黒鉛粒子（Ｂ）が排出されることがなく、かつグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。このような結合としては、例えばグラファイト層（Ａ）の炭素原子と、複数の黒鉛粒子（Ｂ）の炭素原子との間の共有結合などが挙げられる。このような共有結合は、例えばグラファイトシート（Ｘ）の形成の際に、熱処理により生成する残渣等の熱分解した界面活性剤の一部の作用により形成されやすくなると考えられる。 It is preferable that at least a portion of the graphite layer (A) and at least a portion of the plurality of graphite particles (B) are bonded. In this case, the graphite particles (B) are not discharged even when cut, and the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced. Examples of such bonds include covalent bonds between carbon atoms of the graphite layer (A) and carbon atoms of the plurality of graphite particles (B). It is thought that such a covalent bond is likely to be formed, for example, during the formation of the graphite sheet (X) due to the action of a part of the thermally decomposed surfactant such as a residue generated by heat treatment.
　複数のグラファイト層（Ａ）の層間の距離は、複数の黒鉛粒子（Ｂ）の平均粒径よりも小さいことが好ましい。また、複数のグラファイト層（Ａ）の層間の距離は、２５μｍ以下であることが好ましい。このような場合、グラファイト層（Ａ）は、黒鉛粒子（Ｂ）をよけるように配列し、その結果、グラファイトシート（Ｘ）の厚さ方向に配列されやすくなる。 The distance between the plurality of graphite layers (A) is preferably smaller than the average particle diameter of the plurality of graphite particles (B). Further, the distance between the plurality of graphite layers (A) is preferably 25 μm or less. In such a case, the graphite layer (A) is arranged so as to avoid the graphite particles (B), and as a result, the graphite layer (A) is likely to be arranged in the thickness direction of the graphite sheet (X).
［第１実施形態、第２実施形態］
　グラファイトシート（Ｘ）の平均厚さは、例えば１μｍ以上１５０μｍ以下であり、１０μｍ以上１２０μｍ以下であることが好ましく、２０μｍ以上１００μｍ以下であることがより好ましい。 [First embodiment, second embodiment]
The average thickness of the graphite sheet (X) is, for example, 1 μm or more and 150 μm or less, preferably 10 μm or more and 120 μm or less, and more preferably 20 μm or more and 100 μm or less.
　グラファイト層（Ａ）の一部は、グラファイトシート（Ｘ）の面方向に延在し、複数の黒鉛粒子（Ｂ）の近傍において、グラファイト層（Ａ）の少なくとも一部は、グラファイトシート（Ｘ）の厚さ方向に延在していることが好ましい。グラファイトシート（Ｘ）の形成において、複数の黒鉛粒子（Ｂ）が存在することにより、その近傍では、形成されるグラファイト層（Ａ）が、厚さ方向の成分を有する方向に配列する割合がより大きくなると考えられる。このように、厚さ方向の成分を持ち、斜め方向を向いて存在しているグラファイト層（Ａ）を有することにより、グラファイトシート（Ｘ）の厚さ方向における熱抵抗を効率的に小さくすることができる。 A portion of the graphite layer (A) extends in the plane direction of the graphite sheet (X), and in the vicinity of the plurality of graphite particles (B), at least a portion of the graphite layer (A) extends in the plane direction of the graphite sheet (X). Preferably, it extends in the thickness direction. In the formation of the graphite sheet (X), due to the presence of a plurality of graphite particles (B), the proportion of the formed graphite layer (A) in the direction having a thickness direction component is higher in the vicinity thereof. It is thought that it will become larger. In this way, by having the graphite layer (A) that has a component in the thickness direction and is oriented diagonally, the thermal resistance in the thickness direction of the graphite sheet (X) can be efficiently reduced. Can be done.
　グラファイトシート（Ｘ）を厚さ方向に２００ｋＰａで圧縮した際のグラファイトシート（Ｘ）の圧縮率は５５％以上であることが好ましい。グラファイトシート（Ｘ）の圧縮率をより大きくすることにより、厚さ方向における熱抵抗をより小さくすることができる。圧縮率は、６０％以上であることがより好ましく、６５％以上であることがさらに好ましい。また、圧縮率は、例えば７５％以下である。なお、圧縮率とは、初期厚さをＴ０、２００ｋＰａの圧力を加えた後に圧力を解除したときの厚さをＴ１として、（Ｔ０－Ｔ１）／Ｔ０の値をパーセント表示したものである。 The compression rate of the graphite sheet (X) when compressed at 200 kPa in the thickness direction is preferably 55% or more. By increasing the compressibility of the graphite sheet (X), the thermal resistance in the thickness direction can be further reduced. The compression rate is more preferably 60% or more, and even more preferably 65% or more. Further, the compression ratio is, for example, 75% or less. Note that the compression ratio is the value of (T0-T1)/T0 expressed as a percentage, where T0 is the initial thickness and T1 is the thickness when the pressure is released after applying a pressure of 200 kPa.
　グラファイトシート（Ｘ）を厚さ方向に２００ｋＰａで圧縮した際のグラファイトシート（Ｘ）の厚さ方向における熱抵抗は０．４Ｋｃｍ２／Ｗ以下であることが好ましい。この場合、グラファイトシート（Ｘ）の厚さ方向における熱抵抗を十分小さくすることができる。グラファイトシート（Ｘ）の厚さ方向における熱抵抗は、０．２７Ｋｃｍ２／Ｗ以下であることがより好ましく、０．２４Ｋｃｍ２／Ｗ以下であることがさらに好ましく、０．１９Ｋｃｍ２／Ｗ以下であることが特に好ましい。グラファイトシート（Ｘ）の厚さ方向における熱抵抗は小さいほど好ましく、前記熱抵抗の下限は特に限定されないが、例えば０．１Ｋｃｍ２／Ｗ以上である。 The thermal resistance in the thickness direction of the graphite sheet (X) when the graphite sheet (X) is compressed in the thickness direction at 200 kPa is preferably 0.4 Kcm 2 /W or less. In this case, the thermal resistance in the thickness direction of the graphite sheet (X) can be made sufficiently small. The thermal resistance in the thickness direction of the graphite sheet (X) is more preferably at most 0.27 Kcm 2 /W, even more preferably at most 0.24 Kcm 2 /W, and even more preferably at most 0.19 Kcm 2 /W. It is particularly preferable that there be. The lower the thermal resistance in the thickness direction of the graphite sheet (X), the more preferable it is, and the lower limit of the thermal resistance is not particularly limited, but is, for example, 0.1 Kcm 2 /W or more.
＜グラファイトシートの製造方法＞
　以下、本開示のグラファイトシートの製造方法について、以下説明する。
　本開示のグラファイトシートの製造方法によれば、厚さ方向における熱抵抗が小さい前述の本開示のグラファイトシート（Ｘ）を簡便な方法で得ることができる。 <Method for manufacturing graphite sheet>
Hereinafter, a method for manufacturing a graphite sheet of the present disclosure will be described below.
According to the method for manufacturing a graphite sheet of the present disclosure, the graphite sheet (X) of the present disclosure described above having low thermal resistance in the thickness direction can be obtained by a simple method.
［第１実施形態］
　第１実施形態のグラファイトシート（Ｘ）の製造方法は、以下に示すように、第１工程と、第２工程と、第３工程とを備える。
　以下、各工程について説明する。 [First embodiment]
The method for manufacturing the graphite sheet (X) of the first embodiment includes a first step, a second step, and a third step, as shown below.
Each step will be explained below.
（第１工程）
　第１工程では、酸化グラフェンと、界面活性剤とを含む溶液又は懸濁液を準備する。 (1st step)
In the first step, a solution or suspension containing graphene oxide and a surfactant is prepared.
　酸化グラフェンとは、グラフェン（主に、炭素原子が六角形のハニカム格子状に配置された構造を有する化合物を含む）が、カルボキシル基、カルボニル基、ヒドロキシル基等の酸素含有基により修飾されたものである。 Graphene oxide is graphene (which mainly includes compounds with a structure in which carbon atoms are arranged in a hexagonal honeycomb lattice) modified with oxygen-containing groups such as carboxyl groups, carbonyl groups, and hydroxyl groups. It is.
　界面活性剤とは、物質の境界面に作用し、性質を変化させる物質をいい、通常、分子内に親水性部分と疎水性部分との両方を含む構造を有している。 A surfactant is a substance that acts on the interface of a substance to change its properties, and usually has a structure that includes both a hydrophilic part and a hydrophobic part within the molecule.
　界面活性剤としては、例えばアニオン系界面活性剤、カチオン系界面活性剤等のイオン系界面活性剤、ノニオン系界面活性剤などが挙げられる。界面活性剤は、イオン系界面活性剤を含むことが好ましく、アニオン系界面活性剤を含むことがより好ましい。このような界面活性剤を用いることにより、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 Examples of the surfactant include anionic surfactants, ionic surfactants such as cationic surfactants, and nonionic surfactants. The surfactant preferably includes an ionic surfactant, and more preferably an anionic surfactant. By using such a surfactant, the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be further reduced.
　アニオン系界面活性剤としては、例えばスルホン酸又はその塩、カルボン酸又はその塩などが挙げられる。スルホン酸の塩、及びカルボン酸の塩としては、例えばスルホン酸及びカルボン酸のリチウム塩、ナトリウム塩、カリウム塩等のアルカリ金属塩、マグネシウム塩、カルシウム塩、バリウム塩等のアルカリ土類金属塩、トリエタノールアミン塩等のアミン塩などが挙げられる。これらの中で、アルカリ金属塩が好ましく、ナトリウム塩及びカリウム塩の少なくとも一方がより好ましく、ナトリウム塩がさらに好ましい。 Examples of anionic surfactants include sulfonic acids or salts thereof, carboxylic acids or salts thereof, and the like. Examples of sulfonic acid salts and carboxylic acid salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkaline earth metal salts such as magnesium salts, calcium salts, and barium salts; Examples include amine salts such as triethanolamine salts. Among these, alkali metal salts are preferred, at least one of sodium salts and potassium salts is more preferred, and sodium salts are even more preferred.
　スルホン酸としては、例えば脂肪族スルホン酸、芳香族スルホン酸等が挙げられる。 Examples of the sulfonic acid include aliphatic sulfonic acid and aromatic sulfonic acid.
　脂肪族スルホン酸としては、例えばオクタンスルホン酸、ドデシルスルホン酸等が挙げられる。脂肪族スルホン酸の塩としては、例えばオクタンスルホン酸ナトリウム、ドデシルスルホン酸ナトリウム等が挙げられる。 Examples of aliphatic sulfonic acids include octane sulfonic acid and dodecyl sulfonic acid. Examples of salts of aliphatic sulfonic acids include sodium octanesulfonate and sodium dodecylsulfonate.
　芳香族スルホン酸としては、例えばドデシルベンゼンスルホン酸等のアルキル基を有する芳香族スルホン酸、ナフタレントリスルホン酸等のアルキル基を有さない芳香族スルホン酸などが挙げられる。芳香族スルホン酸の塩としては、例えばドデシルベンゼンスルホン酸ナトリウム等のアルキル基を有する芳香族スルホン酸の塩、ナフタレントリスルホン酸三ナトリウム等のアルキル基を有さない芳香族スルホン酸の塩などが挙げられる。 Examples of the aromatic sulfonic acid include aromatic sulfonic acids having an alkyl group such as dodecylbenzenesulfonic acid, and aromatic sulfonic acids not having an alkyl group such as naphthalenetrisulfonic acid. Examples of salts of aromatic sulfonic acids include salts of aromatic sulfonic acids having an alkyl group such as sodium dodecylbenzenesulfonate, salts of aromatic sulfonic acids having no alkyl group such as trisodium naphthalene trisulfonate, etc. Can be mentioned.
　カルボン酸としては、例えばテトラデカン酸（ミリスチン酸）、ヘキサデカン酸（パルミチン酸）、オクタデカン酸（ステアリン酸）等が挙げられる。カルボン酸の塩としては、例えばミリスチン酸ナトリウム、パルミチン酸ナトリウム、ステアリン酸ナトリウムなどが挙げられる。 Examples of the carboxylic acid include tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), and the like. Examples of carboxylic acid salts include sodium myristate, sodium palmitate, and sodium stearate.
　アニオン系界面活性剤は、脂肪族スルホン酸及びその塩並びに芳香族スルホン酸及びその塩のうちの少なくとも一種を含むことが好ましく、脂肪族スルホン酸の塩及び芳香族スルホン酸の塩のうちの少なくとも一方を含むことがより好ましい。この場合、より効果的に、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 The anionic surfactant preferably contains at least one of aliphatic sulfonic acids and salts thereof, and aromatic sulfonic acids and salts thereof, and at least one of aliphatic sulfonic acids and salts thereof. It is more preferable to include one or the other. In this case, the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be more effectively reduced.
　芳香族スルホン酸及びその塩は、アルキル基を有する芳香族スルホン酸及びその塩を含むことが好ましく、アルキル基を有する芳香族スルホン酸の塩を含むことがより好ましい。この場合、界面活性剤が、芳香環に結合するアルキル基を有していることで、より効果的に、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 The aromatic sulfonic acid and its salts preferably include aromatic sulfonic acids and salts thereof having an alkyl group, and more preferably include salts of aromatic sulfonic acids having an alkyl group. In this case, since the surfactant has an alkyl group bonded to an aromatic ring, it is possible to more effectively reduce the thermal resistance in the thickness direction of the obtained graphite sheet (X).
　アルキル基としては、例えばｎ－オクチル基、ｎ－ドデシル基、ｎ－テトラデシル基、ｎ－ヘキサデシル基、ｎ－オクタデシル基、ｎ－イコシル基等の直鎖状アルキル基、イソオクチル基、イソドデシル基等の分岐鎖状アルキル基などが挙げられる。アルキル基としては、直鎖状アルキル基が好ましく、ｎ－ドデシル基がより好ましい。 Examples of the alkyl group include linear alkyl groups such as n-octyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-icosyl group, isooctyl group, isododecyl group, etc. Examples include branched alkyl groups. The alkyl group is preferably a linear alkyl group, more preferably an n-dodecyl group.
　アルキル基の炭素鎖の長さは、９以上１７以下であることが好ましい。炭素鎖の長さが９以上であると、グラファイトシート（Ｘ）の熱抵抗をより小さくすることができる。炭素鎖の長さが１７以下であると、酸化グラフェン分散体をより安定させることができる。アルキル基の炭素鎖の長さは、１０以上１４以下であることがより好ましく、１２であることが最も好ましい。「アルキル基の炭素鎖の長さ」とは、アルキル基における炭素鎖のうち最も長いものが有する炭素数をいう。 The length of the carbon chain of the alkyl group is preferably 9 or more and 17 or less. When the length of the carbon chain is 9 or more, the thermal resistance of the graphite sheet (X) can be further reduced. When the length of the carbon chain is 17 or less, the graphene oxide dispersion can be made more stable. The length of the carbon chain of the alkyl group is more preferably 10 or more and 14 or less, most preferably 12. "Length of carbon chain of alkyl group" refers to the number of carbon atoms in the longest carbon chain in the alkyl group.
　第１工程における溶液又は懸濁液の調製は、例えば界面活性剤の水溶液に、酸化グラフェンの水溶液を加え、得られた混合物を、例えば撹拌脱泡機等を用いて撹拌することなどにより行うことができる。 The solution or suspension in the first step may be prepared by, for example, adding an aqueous solution of graphene oxide to an aqueous solution of a surfactant, and stirring the resulting mixture using, for example, a stirring defoaming machine. Can be done.
（第２工程）
　第２工程では、第１工程で準備した溶液又は懸濁液を用いて、前駆体フィルムを形成する。 (Second process)
In the second step, a precursor film is formed using the solution or suspension prepared in the first step.
　第２工程における前駆体フィルムは、例えば第１工程で得られた溶液又は懸濁液を、ＰＥＴ等の基材上に、コーター等の装置により所定の厚さに塗布した後、乾燥を行うことなどにより形成することができる。塗布の厚さとしては、例えば０．１ｍｍ以上３ｍｍ以下である。乾燥の温度としては、例えば３０℃以上８０℃以下である。 The precursor film in the second step is produced by, for example, applying the solution or suspension obtained in the first step onto a base material such as PET to a predetermined thickness using a device such as a coater, and then drying it. It can be formed by, for example. The coating thickness is, for example, 0.1 mm or more and 3 mm or less. The drying temperature is, for example, 30°C or higher and 80°C or lower.
（第３工程）
　第３工程では、第２工程で形成した前駆体フィルムを熱処理して、複数のグラファイト層（Ａ）を有するグラファイトシート（Ｘ）を得る。 (3rd step)
In the third step, the precursor film formed in the second step is heat-treated to obtain a graphite sheet (X) having a plurality of graphite layers (A).
　第３工程における熱処理は、例えば第２工程で形成した前駆体フィルムを焼成すること等により行うことができる。この焼成は、通常、前駆体フィルムに荷重をかけて行う。この焼成の温度は、例えば２０００℃以上３０００℃以下であり、２５００℃以上２８００℃以下であることが好ましい。 The heat treatment in the third step can be performed, for example, by firing the precursor film formed in the second step. This firing is usually performed by applying a load to the precursor film. The temperature of this firing is, for example, 2000°C or more and 3000°C or less, preferably 2500°C or more and 2800°C or less.
　以上のようにして、複数のグラファイト層（Ａ）を有するグラファイトシート（Ｘ）を得ることができる。 In the above manner, a graphite sheet (X) having a plurality of graphite layers (A) can be obtained.
［第２実施形態］
　第２実施形態のグラファイトシートの製造方法は、前述の第１実施形態のグラファイトシートの製造方法とは、第１工程において、酸化グラフェン及び界面活性剤に加えて、複数の黒鉛粒子（Ｂ）をさらに含む溶液又は懸濁液を準備することにおいて異なり、それ以外は、同様である。 [Second embodiment]
The graphite sheet manufacturing method of the second embodiment differs from the graphite sheet manufacturing method of the first embodiment described above in that, in the first step, a plurality of graphite particles (B) are added in addition to graphene oxide and a surfactant. They differ in that they further contain solutions or suspensions, but are otherwise similar.
（第１工程）
　第１工程では、酸化グラフェンと、界面活性剤と、複数の黒鉛粒子（Ｂ）とを含む溶液又は懸濁液を準備する。酸化グラフェン及び界面活性剤については、第１実施形態のグラファイトシートの製造方法で用いるものと同じである。 (1st step)
In the first step, a solution or suspension containing graphene oxide, a surfactant, and a plurality of graphite particles (B) is prepared. The graphene oxide and surfactant are the same as those used in the graphite sheet manufacturing method of the first embodiment.
　複数の黒鉛粒子（Ｂ）は、球状及び鱗片状の少なくとも一方であることが好ましい。 It is preferable that the plurality of graphite particles (B) have at least one of a spherical shape and a scaly shape.
　複数の黒鉛粒子（Ｂ）は、人造黒鉛の粒子を含むことが好ましい。 It is preferable that the plurality of graphite particles (B) include particles of artificial graphite.
　複数の黒鉛粒子（Ｂ）の平均粒径は、１０μｍ以上１００μｍ以下であることが好ましい。黒鉛粒子（Ｂ）の平均粒径を前記範囲とすることにより、グラファイトシート（Ｘ）において、厚さ方向の成分を有する方向に配列するグラファイト層（Ａ）の割合がより多くなると考えられ、その結果、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。黒鉛粒子（Ｂ）の平均粒径は、１５μｍ以上６０μｍ以下であることがより好ましく、１８μｍ以上４０μｍ以下であることがさらに好ましい。 The average particle diameter of the plurality of graphite particles (B) is preferably 10 μm or more and 100 μm or less. It is thought that by setting the average particle size of the graphite particles (B) within the above range, in the graphite sheet (X), the proportion of the graphite layer (A) arranged in a direction having a thickness direction component increases. As a result, the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced. The average particle diameter of the graphite particles (B) is more preferably 15 μm or more and 60 μm or less, and even more preferably 18 μm or more and 40 μm or less.
　複数の黒鉛粒子（Ｂ）の重量比は、酸化グラフェンの固形分及び複数の黒鉛粒子の総量に対して、１％以上７０％以下であることが好ましい。この場合、圧縮率の低い強固なグラファイトシート（Ｘ）を得ることができる。前記重量比は、１０％以上６０％以下であることがより好ましく、２５％以上４５％以下であることがさらに好ましい。 The weight ratio of the plurality of graphite particles (B) is preferably 1% or more and 70% or less with respect to the solid content of graphene oxide and the total amount of the plurality of graphite particles. In this case, a strong graphite sheet (X) with low compression ratio can be obtained. The weight ratio is more preferably 10% or more and 60% or less, and even more preferably 25% or more and 45% or less.
　第３工程で得られるグラファイトシート（Ｘ）は、グラファイト層（Ａ）の層間及び層内の少なくとも一部に複数の黒鉛粒子（Ｂ）を有していることが好ましい。 The graphite sheet (X) obtained in the third step preferably has a plurality of graphite particles (B) between the graphite layers (A) and at least partially within the layers.
　以下、本開示を実施例によってより具体的に説明するが、本開示は実施例のみに限定されるものではない。 Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to the Examples.
＜グラファイトシートの製造＞
　以下の手順により、グラファイトシートを製造した。
［第１工程］（溶液又は懸濁液の調製）
（原材料）
　溶液又は懸濁液の調製に用いた原材料について以下に示す。
・酸化グラフェン：酸化グラフェン水分散体（固形分濃度１．８重量％）
・黒鉛粒子：富士黒鉛工業社製のＭＡＧ－４（平均粒径３．９μｍ）、ＳＧＳ２０（平均粒径２０μｍ）、Ｇ３（平均粒径３８μｍ）
・界面活性剤：
　ＳＤＢＳ：ドデシルベンゼンスルホン酸ナトリウム
　ＳＤＳ：ドデシルスルホン酸ナトリウム
　ＳＯ：オクタンスルホン酸ナトリウム
　ＴＮＴＳ：ナフタレントリスルホン酸三ナトリウム <Manufacture of graphite sheet>
A graphite sheet was manufactured by the following procedure.
[First step] (Preparation of solution or suspension)
(raw materials)
The raw materials used for preparing the solution or suspension are shown below.
・Graphene oxide: graphene oxide aqueous dispersion (solid content concentration 1.8% by weight)
・Graphite particles: MAG-4 (average particle size 3.9 μm), SGS20 (average particle size 20 μm), G3 (average particle size 38 μm) manufactured by Fuji Graphite Industries Co., Ltd.
・Surfactant:
SDBS: Sodium dodecylbenzenesulfonate SDS: Sodium dodecylsulfonate SO: Sodium octanesulfonate TNTS: Trisodium naphthalene trisulfonate
（実施例１）
　平均粒径２０μｍの人造黒鉛の粉末０．４５ｇを小瓶に入れ、これに、ドデシルベンゼンスルホン酸ナトリウム（ＳＤＢＳ）の水溶液（１．５重量％）１２ｇを加えて撹拌した。次に、これに、酸化グラフェン水分散体（１．８重量％）４５ｇを追加し、撹拌脱泡機で撹拌し、溶液又は懸濁液を調製した。
（実施例２～５）
　下記表１に示す平均粒径の黒鉛粒子の粉末を表１に示す重量％になる量を用い、表１に示す種類及び重量％になる量の界面活性剤を用いた以外は、実施例１と同様にして、溶液又は懸濁液を調製した。
（実施例６）
　黒鉛粒子を配合しなかった以外は、実施例１と同様にして、溶液又は懸濁液を調製した。
（実施例７～９）
　表１に示す種類及び重量％になる量の界面活性剤を用いた以外は、実施例６と同様にして、溶液又は懸濁液を調製した。
（比較例１）
　小瓶に、酸化グラフェン水分散体（１．８重量％）４５ｇを入れ、撹拌脱泡機で撹拌し、溶液又は懸濁液を調製した。 (Example 1)
0.45 g of artificial graphite powder with an average particle size of 20 μm was placed in a small bottle, and 12 g of an aqueous solution (1.5% by weight) of sodium dodecylbenzenesulfonate (SDBS) was added thereto and stirred. Next, 45 g of graphene oxide aqueous dispersion (1.8% by weight) was added to this and stirred with a stirring defoamer to prepare a solution or suspension.
(Examples 2 to 5)
Example 1 except that graphite particle powder having the average particle diameter shown in Table 1 below was used in an amount to give the weight % shown in Table 1, and a surfactant of the type and weight % shown in Table 1 was used. A solution or suspension was prepared in the same manner as above.
(Example 6)
A solution or suspension was prepared in the same manner as in Example 1, except that graphite particles were not blended.
(Examples 7 to 9)
A solution or suspension was prepared in the same manner as in Example 6, except that the types and weight percentages of surfactants shown in Table 1 were used.
(Comparative example 1)
45 g of graphene oxide aqueous dispersion (1.8% by weight) was placed in a small bottle and stirred with a stirring defoamer to prepare a solution or suspension.
［第２工程］（前駆体フィルムの形成）
（実施例１～９及び比較例１）
　第１工程で得られた溶液又は懸濁液を、１．５ｍｍのギャップのコーターで、ＰＥＴ基材上に塗布した。次に、これを６０℃で乾燥し、前駆体フィルム（焼成前の原料シート）を形成した。 [Second step] (Formation of precursor film)
(Examples 1 to 9 and Comparative Example 1)
The solution or suspension obtained in the first step was coated onto the PET substrate with a coater with a gap of 1.5 mm. Next, this was dried at 60° C. to form a precursor film (raw material sheet before firing).
［第３工程］（熱処理によりグラファイトシートを得る）
（実施例１～９及び比較例１）
　第２工程で形成した前駆体フィルムを、黒鉛板に１枚ずつ挟み、高密度の黒鉛板で荷重をかけて、２７００℃で焼成することにより熱処理し、複数のグラファイト層を有するグラファイトシートを得た。 [Third step] (obtain graphite sheet by heat treatment)
(Examples 1 to 9 and Comparative Example 1)
The precursor films formed in the second step were sandwiched one by one between graphite plates, loaded with high-density graphite plates, and heat treated by firing at 2700°C to obtain a graphite sheet having multiple graphite layers. Ta.
　実施例１のグラファイトシートの断面の電子顕微鏡写真を図１に、実施例６のグラファイトシートの断面の電子顕微鏡写真を図２に示す。これらの電子顕微鏡写真に示されるように、得られたグラファイトシートにおいて、厚さ方向の成分を有する方向に配列したグラファイト層の割合が多くなっている。特に、図１で示されるように、黒鉛粒子の近傍において、このような方向の配列の傾向が高くなっていることが分かる。 An electron micrograph of a cross section of the graphite sheet of Example 1 is shown in FIG. 1, and an electron micrograph of a cross section of the graphite sheet of Example 6 is shown in FIG. As shown in these electron micrographs, in the obtained graphite sheet, the proportion of graphite layers arranged in a direction having a thickness direction component is high. In particular, as shown in FIG. 1, it can be seen that the tendency for alignment in this direction is high in the vicinity of graphite particles.
＜評価＞
　前記得られたグラファイトシートについて、以下の項目を下記方法により評価した。評価結果を下記表１に示す。 <Evaluation>
The graphite sheet obtained above was evaluated for the following items by the following methods. The evaluation results are shown in Table 1 below.
［厚さ方向における熱抵抗］
　以下のようにして、（ＡＳＴＭ　Ｄ５４７０に準拠し、）グラファイトシートを厚さ方向に２００ｋＰａで圧縮した際の熱抵抗を測定した。
　グラファイトシートに厚さ方向に２００ｋＰａで加圧した状態になるようにして、２枚の金属ブロックの間に、グラファイトシートを挟み、一方の金属ブロックから他方の金属ブロックへの定常状態における熱抵抗を測定した。各金属ブロックの温度を、熱電対により温度を測定した。
　下記式（１）により、熱抵抗（Ｋｃｍ２／Ｗ）を算出した。
　熱抵抗（Ｋｃｍ２／Ｗ）＝温度差ΔＴ（Ｋ）×グラファイトシートの面の面積（ｃｍ２）／通過する熱量（Ｗ）・・・（１） [Thermal resistance in the thickness direction]
The thermal resistance when the graphite sheet was compressed at 200 kPa in the thickness direction (according to ASTM D5470) was measured as follows.
The graphite sheet was put under pressure of 200 kPa in the thickness direction, and the graphite sheet was sandwiched between two metal blocks, and the thermal resistance in a steady state from one metal block to the other metal block was measured. It was measured. The temperature of each metal block was measured using a thermocouple.
The thermal resistance (Kcm 2 /W) was calculated using the following formula (1).
Thermal resistance (Kcm 2 /W) = temperature difference ΔT (K) x area of graphite sheet surface (cm 2 )/amount of heat passing through (W)... (1)
［圧縮後平均厚さ］
　グラファイトシートを厚さ方向に２００ｋＰａで加圧したときのグラファイトシートの厚みを、１０点測定し、算術平均を圧縮後平均厚さ（μｍ）とした。 [Average thickness after compression]
The thickness of the graphite sheet when the graphite sheet was pressed at 200 kPa in the thickness direction was measured at 10 points, and the arithmetic mean was taken as the average thickness after compression (μm).
［厚さ方向における熱伝導率］
　前記測定した厚さ方向における熱抵抗、及び圧縮後平均厚さの測定値から、下記式（２）により、厚さ方向における熱伝導率を算出した。
　厚さ方向における熱伝導率（Ｗ／ｍＫ）
　＝圧縮後平均厚さ（μｍ）／（厚さ方向における熱抵抗（Ｗ／）×１００）
　・・・（２） [Thermal conductivity in the thickness direction]
From the measured thermal resistance in the thickness direction and the measured value of the average thickness after compression, the thermal conductivity in the thickness direction was calculated using the following formula (2).
Thermal conductivity in the thickness direction (W/mK)
= Average thickness after compression (μm)/(Thermal resistance in thickness direction (W/) x 100)
...(2)
［材料熱伝導率］
　厚さ方向の加圧力と、厚さ方向の熱抵抗との関係について測定した。加圧力を、５０ｋＰａ、１００ｋＰａ、２００ｋＰａ、３００ｋＰａ、５００ｋＰａ、６００ｋＰａの６点とし、それぞれの場合の厚さ方向の熱抵抗を測定した。各加圧力に対する熱抵抗の各測定値をプロットし、その傾きを求め、この傾きの逆数を、材料熱伝導率とした。 [Material thermal conductivity]
The relationship between the pressing force in the thickness direction and the thermal resistance in the thickness direction was measured. The pressing force was set at six points: 50 kPa, 100 kPa, 200 kPa, 300 kPa, 500 kPa, and 600 kPa, and the thermal resistance in the thickness direction was measured for each case. The measured values of thermal resistance for each pressing force were plotted, the slope thereof was determined, and the reciprocal of this slope was taken as the material thermal conductivity.
［外観］
　グラファイトシートの外観を目視で評価した。割れが認められた場合は、「割れ」と記載した。 [exterior]
The appearance of the graphite sheet was visually evaluated. If cracking was observed, it was written as "cracking."
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果から分かるように、実施例６～９（第１実施形態）及び実施例１～５（第２実施形態）のグラファイトシートは、比較例１に比べて、熱抵抗を小さくすることができた。 As can be seen from the results in Table 1, the graphite sheets of Examples 6 to 9 (first embodiment) and Examples 1 to 5 (second embodiment) have lower thermal resistance than Comparative Example 1. was completed.
（まとめ）
　上述の実施形態及び実施例から明らかなように、本開示の第一の態様に係るグラファイトシート（Ｘ）は、複数のグラファイト層（Ａ）を有する。 (summary)
As is clear from the above embodiments and examples, the graphite sheet (X) according to the first aspect of the present disclosure has a plurality of graphite layers (A).
　第一の態様によれば、グラファイトシート（Ｘ）の厚さ方向における熱抵抗を小さくすることができる。 According to the first aspect, the thermal resistance in the thickness direction of the graphite sheet (X) can be reduced.
　本開示の第二の態様では、第一の態様において、グラファイト層（Ａ）の層間及び層内の少なくとも一部に、複数の黒鉛粒子（Ｂ）をさらに有する。 In the second aspect of the present disclosure, in the first aspect, a plurality of graphite particles (B) are further included between the graphite layers (A) and at least partially within the layers.
　第二の態様によれば、グラファイト層（Ａ）の構造を維持したまま、黒鉛粒子が含有されることにより、グラファイト層（Ａ）の厚さ方向の成分を有する方向に配列する割合をより多くすることができると考えられ、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the second aspect, the graphite particles are contained while maintaining the structure of the graphite layer (A), thereby increasing the proportion of the graphite layer (A) arranged in a direction having a thickness direction component. It is considered possible to reduce the thermal resistance in the thickness direction of the graphite sheet (X).
　本開示の第三の態様では、第二の態様において、グラファイト層（Ａ）の少なくとも一部と、複数の黒鉛粒子（Ｂ）の少なくとも一部とが結合している。 In the third aspect of the present disclosure, in the second aspect, at least a portion of the graphite layer (A) and at least a portion of the plurality of graphite particles (B) are combined.
　第三の態様によれば、切断したときでも黒鉛粒子（Ｂ）が排出されることがなく、かつグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the third aspect, the graphite particles (B) are not discharged even when cut, and the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
　本開示の第四の態様では、第二又は第三の態様において、複数の黒鉛粒子（Ｂ）の平均粒径は、グラファイト層（Ａ）の平均厚さよりも大きい。 In the fourth aspect of the present disclosure, in the second or third aspect, the average particle size of the plurality of graphite particles (B) is larger than the average thickness of the graphite layer (A).
　第四の態様によれば、黒鉛粒子（Ｂ）として、グラファイト層（Ａ）の平均厚さよりも大きい平均粒径のものを用いることで、厚さ方向の成分を有する方向に配列するグラファイト層（Ａ）の割合をより多くすることができ、その結果、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the fourth aspect, by using graphite particles (B) having an average particle diameter larger than the average thickness of the graphite layer (A), the graphite layer ( The proportion of A) can be increased, and as a result, the thermal resistance in the thickness direction of the graphite sheet (X) can be made smaller.
　本開示の第五の態様では、第二から第四のいずれか一の態様において、グラファイト層（Ａ）の一部は、グラファイトシート（Ｘ）の面方向に延在し、複数の黒鉛粒子（Ｂ）の近傍において、グラファイト層（Ａ）の少なくとも一部は、グラファイトシート（Ｘ）の厚さ方向に延在している。 In a fifth aspect of the present disclosure, in any one of the second to fourth aspects, a part of the graphite layer (A) extends in the plane direction of the graphite sheet (X), and a plurality of graphite particles ( In the vicinity of B), at least a portion of the graphite layer (A) extends in the thickness direction of the graphite sheet (X).
　第五の態様によれば、グラファイト層（Ａ）が黒鉛粒子（Ｂ）の近傍において、グラファイトシート（Ｘ）の厚さ方向の成分を持ち、斜め方向を向いて存在していることにより、グラファイトシート（Ｘ）の厚さ方向における熱抵抗を効率よく小さくすることができる。 According to the fifth aspect, the graphite layer (A) has a component in the thickness direction of the graphite sheet (X) in the vicinity of the graphite particles (B) and is oriented obliquely, so that the graphite The thermal resistance in the thickness direction of the sheet (X) can be efficiently reduced.
　本開示の第六の態様では、第一から第五のいずれか一の態様において、グラファイトシート（Ｘ）を厚さ方向に２００ｋＰａで圧縮した際のグラファイトシート（Ｘ）の圧縮率は５５％以上である。 In a sixth aspect of the present disclosure, in any one of the first to fifth aspects, the compression rate of the graphite sheet (X) when compressed at 200 kPa in the thickness direction is 55% or more. It is.
　第六の態様によれば、グラファイトシート（Ｘ）の圧縮率をより大きくすることにより、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the sixth aspect, by increasing the compression ratio of the graphite sheet (X), the thermal resistance in the thickness direction of the graphite sheet (X) can be further reduced.
　本開示の第七の態様では、第一から第六のいずれか一の態様において、グラファイトシート（Ｘ）を厚さ方向に２００ｋＰａで圧縮した際のグラファイトシート（Ｘ）の厚さ方向における熱抵抗は０．１Ｋｃｍ２／Ｗ以上０．４Ｋｃｍ２／Ｗ以下である。 In a seventh aspect of the present disclosure, in any one of the first to sixth aspects, thermal resistance in the thickness direction of the graphite sheet (X) when the graphite sheet (X) is compressed at 200 kPa in the thickness direction is 0.1 Kcm 2 /W or more and 0.4 Kcm 2 /W or less.
　第七の態様によれば、グラファイトシート（Ｘ）の厚さ方向における熱抵抗を十分小さくすることができる。 According to the seventh aspect, the thermal resistance in the thickness direction of the graphite sheet (X) can be made sufficiently small.
　本開示の第八の態様では、第一から第七のいずれか一の態様において、グラファイト層（Ａ）は、酸化グラフェンから形成されたものである。 In an eighth aspect of the present disclosure, in any one of the first to seventh aspects, the graphite layer (A) is formed from graphene oxide.
　第八の態様によれば、グラファイト層（Ａ）を、酸化グラフェンから形成することにより、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the eighth aspect, by forming the graphite layer (A) from graphene oxide, it is possible to further reduce the thermal resistance in the thickness direction of the graphite sheet (X).
　本開示の第九の態様に係るグラファイトシート（Ｘ）の製造方法では、第１工程と、第２工程と、第３工程とを備える。第１工程では、酸化グラフェンと、界面活性剤とを含む溶液又は懸濁液を準備する。第２工程では、前記溶液又は懸濁液を用いて、前駆体フィルムを形成する。第３工程では、前記前駆体フィルムを熱処理して、複数のグラファイト層（Ａ）を有するグラファイトシート（Ｘ）を得る。 The method for manufacturing a graphite sheet (X) according to the ninth aspect of the present disclosure includes a first step, a second step, and a third step. In the first step, a solution or suspension containing graphene oxide and a surfactant is prepared. In the second step, a precursor film is formed using the solution or suspension. In the third step, the precursor film is heat-treated to obtain a graphite sheet (X) having a plurality of graphite layers (A).
　第九の態様によれば、厚さ方向における熱抵抗が小さいグラファイトシート（Ｘ）を簡便な方法で得ることができる。 According to the ninth aspect, a graphite sheet (X) with low thermal resistance in the thickness direction can be obtained by a simple method.
　本開示の第十の態様では、第九の態様において、第１工程における溶液又は懸濁液が、複数の黒鉛粒子（Ｂ）をさらに含む。 In a tenth aspect of the present disclosure, in the ninth aspect, the solution or suspension in the first step further contains a plurality of graphite particles (B).
　第十の態様によれば、溶液又は懸濁液に黒鉛粒子（Ｂ）をさらに含ませることで、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the tenth aspect, by further including graphite particles (B) in the solution or suspension, the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be further reduced.
　本開示の第十一の態様では、第十の態様において、第３工程におけるグラファイトシート（Ｘ）において、グラファイト層（Ａ）の層間及び層内の少なくとも一部に複数の黒鉛粒子（Ｂ）を有する。 In an eleventh aspect of the present disclosure, in the tenth aspect, in the graphite sheet (X) in the third step, a plurality of graphite particles (B) are added between and at least in part of the graphite layer (A). have
　第十一の態様によれば、得られるグラファイトシート（Ｘ）において、黒鉛粒子（Ｂ）が含有されることにより、グラファイト層（Ａ）の厚さ方向の成分を有する方向に配列する割合をより多くすることができると考えられ、グラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the eleventh aspect, the content of the graphite particles (B) in the obtained graphite sheet (X) increases the proportion of the graphite layer (A) arranged in the direction having the thickness direction component. It is thought that it is possible to increase the thermal resistance in the thickness direction of the graphite sheet (X).
　本開示の第十二の態様では、第十又は第十一の態様において、複数の黒鉛粒子（Ｂ）は、球状及び鱗片状の少なくとも一方である。 In a twelfth aspect of the present disclosure, in the tenth or eleventh aspect, the plurality of graphite particles (B) are at least one of spherical and scaly.
　第十二の態様によれば、黒鉛粒子（Ｂ）として前記形状のものを用いることにより、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the twelfth aspect, by using graphite particles (B) having the above shape, the thermal resistance in the thickness direction of the graphite sheet (X) obtained can be further reduced.
　本開示の第十三の態様では、第十から第十二のいずれか一の態様において、複数の黒鉛粒子（Ｂ）は、人造黒鉛の粒子を含む。 In a thirteenth aspect of the present disclosure, in any one of the tenth to twelfth aspects, the plurality of graphite particles (B) include particles of artificial graphite.
　第十三の態様によれば、黒鉛粒子（Ｂ）として人造黒鉛の粒子を用いることにより、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the thirteenth aspect, by using artificial graphite particles as the graphite particles (B), the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be made smaller.
　本開示の第十四の態様では、第十から第十三のいずれか一の態様において、複数の黒鉛粒子（Ｂ）の平均粒径は、１０μｍ以上１００μｍ以下である。 In a fourteenth aspect of the present disclosure, in any one of the tenth to thirteenth aspects, the average particle size of the plurality of graphite particles (B) is 10 μm or more and 100 μm or less.
　第十四の態様によれば、黒鉛粒子（Ｂ）として、前記範囲の平均粒径のものを用いることにより、厚さ方向の成分を有する方向に配列するグラファイト層（Ａ）の割合がより多くなると考えられ、その結果、得られるグラファイトシート（Ｘ）の熱抵抗をより小さくすることができる。 According to the fourteenth aspect, by using graphite particles (B) having an average particle size within the above range, the proportion of the graphite layer (A) arranged in a direction having a thickness direction component is increased. As a result, the thermal resistance of the graphite sheet (X) obtained can be further reduced.
　本開示の第十五の態様では、第九から第十四のいずれか一の態様において、界面活性剤は、アニオン系界面活性剤を含む。 In a fifteenth aspect of the present disclosure, in any one of the ninth to fourteenth aspects, the surfactant includes an anionic surfactant.
　第十五の態様によれば、界面活性剤として、アニオン系のものを用いることにより、より効果的に、得られるグラファイトシート（Ｘ）の厚さ方向における熱抵抗をより小さくすることができる。 According to the fifteenth aspect, by using an anionic surfactant as the surfactant, the thermal resistance in the thickness direction of the obtained graphite sheet (X) can be more effectively reduced.
　本開示の第十六の態様では、第十五の態様において、アニオン系界面活性剤は、脂肪族スルホン酸及びその塩並びに芳香族スルホン酸及びその塩のうちの少なくとも一種を含む。 In a sixteenth aspect of the present disclosure, in the fifteenth aspect, the anionic surfactant contains at least one of an aliphatic sulfonic acid and a salt thereof, and an aromatic sulfonic acid and a salt thereof.
　第十六の態様によれば、アニオン系界面活性剤として、スルホン酸又はその塩を用いることにより、より効果的に、得られるグラファイトシート（Ｘ）の熱抵抗をより小さくすることができる。 According to the sixteenth aspect, by using sulfonic acid or a salt thereof as the anionic surfactant, the thermal resistance of the obtained graphite sheet (X) can be more effectively reduced.
　本開示の第十七の態様では、第十六の態様において、芳香族スルホン酸及びその塩は、アルキル基を有する芳香族スルホン酸及びその塩を含む。 In a seventeenth aspect of the present disclosure, in the sixteenth aspect, the aromatic sulfonic acid and its salt include an aromatic sulfonic acid and its salt having an alkyl group.
　第十七の態様によれば、芳香族スルホン酸及びその塩として、芳香環に結合するアルキル基を有するものを用いることで、より効果的に、得られるグラファイトシート（Ｘ）の熱抵抗をより小さくすることができる。 According to the seventeenth aspect, by using aromatic sulfonic acids and salts thereof having an alkyl group bonded to an aromatic ring, the thermal resistance of the obtained graphite sheet (X) can be more effectively improved. Can be made smaller.
　本開示の第十八の態様では、第十から第十七のいずれか一の態様において、第１工程における溶液又は懸濁液において、酸化グラフェンの固形分及び複数の黒鉛粒子（Ｂ）の総量に対する複数の黒鉛粒子（Ｂ）の重量比は１％以上７０％以下である。 In an eighteenth aspect of the present disclosure, in any one of the tenth to seventeenth aspects, in the solution or suspension in the first step, the solid content of graphene oxide and the total amount of the plurality of graphite particles (B) The weight ratio of the plurality of graphite particles (B) to the graphite particles is 1% or more and 70% or less.
　第十八の態様によれば、酸化グラフェン及び黒鉛粒子（Ｂ）の合計に対する黒鉛粒子（Ｂ）の比率を前記範囲とすることで、圧縮率の低い強固なグラファイトシート（Ｘ）を得ることができる。 According to the eighteenth aspect, by setting the ratio of graphite particles (B) to the total of graphene oxide and graphite particles (B) within the above range, it is possible to obtain a strong graphite sheet (X) with a low compressibility. can.

Claims (18)

  1. 　複数のグラファイト層を有するグラファイトシート。 Graphite sheet with multiple graphite layers.
  2. 　前記グラファイト層の層間及び層内の少なくとも一部に、複数の黒鉛粒子をさらに有する請求項１に記載のグラファイトシート。 The graphite sheet according to claim 1, further comprising a plurality of graphite particles between and at least part of the graphite layer.
  3. 　前記グラファイト層の少なくとも一部と、前記複数の黒鉛粒子の少なくとも一部とが結合している請求項２に記載のグラファイトシート。 The graphite sheet according to claim 2, wherein at least a portion of the graphite layer and at least a portion of the plurality of graphite particles are bonded.
  4. 　前記複数の黒鉛粒子の平均粒径は、前記グラファイト層の平均厚さよりも大きい請求項２又は３に記載のグラファイトシート。 The graphite sheet according to claim 2 or 3, wherein the average particle diameter of the plurality of graphite particles is larger than the average thickness of the graphite layer.
  5. 　前記グラファイト層の一部は、前記グラファイトシートの面方向に延在し、
    　前記複数の黒鉛粒子の近傍において、前記グラファイト層の少なくとも一部は、前記グラファイトシートの厚さ方向に延在している請求項２又は３に記載のグラファイトシート。     A portion of the graphite layer extends in the plane direction of the graphite sheet,
    The graphite sheet according to claim 2 or 3, wherein at least a portion of the graphite layer extends in the thickness direction of the graphite sheet in the vicinity of the plurality of graphite particles.
  6. 　前記グラファイトシートを厚さ方向に２００ｋＰａで圧縮した際の前記グラファイトシートの圧縮率は５５％以上である請求項１又は２に記載のグラファイトシート。 The graphite sheet according to claim 1 or 2, wherein the compression ratio of the graphite sheet when compressed in the thickness direction at 200 kPa is 55% or more.
  7. 　前記グラファイトシートを厚さ方向に２００ｋＰａで圧縮した際の前記グラファイトシートの厚さ方向における熱抵抗は０．１Ｋｃｍ２／Ｗ以上０．４Ｋｃｍ２／Ｗ以下である請求項１又は２に記載のグラファイトシート。 The graphite according to claim 1 or 2, wherein the graphite sheet has a thermal resistance in the thickness direction of 0.1 Kcm 2 /W or more and 0.4 Kcm 2 /W or less when the graphite sheet is compressed in the thickness direction at 200 kPa. sheet.
  8. 　前記グラファイト層は、酸化グラフェンから形成されたものである請求項１又は２に記載のグラファイトシート。 The graphite sheet according to claim 1 or 2, wherein the graphite layer is formed from graphene oxide.
  9. 　酸化グラフェンと、界面活性剤とを含む溶液又は懸濁液を準備する第１工程と、
    　前記溶液又は懸濁液を用いて、前駆体フィルムを形成する第２工程と、
    　前記前駆体フィルムを熱処理して、複数のグラファイト層を有するグラファイトシートを得る第３工程と
    　を備えるグラファイトシートの製造方法。     A first step of preparing a solution or suspension containing graphene oxide and a surfactant;
    a second step of forming a precursor film using the solution or suspension;
    and a third step of heat-treating the precursor film to obtain a graphite sheet having a plurality of graphite layers.
  10. 　前記第１工程における前記溶液又は懸濁液が、複数の黒鉛粒子をさらに含む請求項９に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 9, wherein the solution or suspension in the first step further contains a plurality of graphite particles.
  11. 　前記第３工程における前記グラファイトシートにおいて、前記グラファイト層の層間及び層内の少なくとも一部に前記複数の黒鉛粒子を有する請求項１０に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 10, wherein the graphite sheet in the third step has the plurality of graphite particles between and at least in part of the graphite layer.
  12. 　前記複数の黒鉛粒子は、球状及び鱗片状の少なくとも一方である請求項１０又は１１に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 10 or 11, wherein the plurality of graphite particles are at least one of spherical and scaly.
  13. 　前記複数の黒鉛粒子は、人造黒鉛の粒子を含む請求項１０又は１１に記載のグラファイトシートの製造方法。 The method for manufacturing a graphite sheet according to claim 10 or 11, wherein the plurality of graphite particles include particles of artificial graphite.
  14. 　前記複数の黒鉛粒子の平均粒径は、１０μｍ以上１００μｍ以下である請求項１０又は１１に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 10 or 11, wherein the average particle diameter of the plurality of graphite particles is 10 μm or more and 100 μm or less.
  15. 　前記界面活性剤は、アニオン系界面活性剤を含む請求項９又は１０に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 9 or 10, wherein the surfactant includes an anionic surfactant.
  16. 　前記アニオン系界面活性剤は、脂肪族スルホン酸及びその塩並びに芳香族スルホン酸及びその塩のうちの少なくとも一種を含む請求項１５に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 15, wherein the anionic surfactant contains at least one of an aliphatic sulfonic acid and its salt, and an aromatic sulfonic acid and its salt.
  17. 　前記芳香族スルホン酸及びその塩は、アルキル基を有する芳香族スルホン酸及びその塩を含む請求項１６に記載のグラファイトシートの製造方法。 The method for producing a graphite sheet according to claim 16, wherein the aromatic sulfonic acid and its salt include an aromatic sulfonic acid and its salt having an alkyl group.
  18. 　前記第１工程における前記溶液又は懸濁液において、前記酸化グラフェンの固形分及び前記複数の黒鉛粒子の総量に対する前記複数の黒鉛粒子の重量比は１％以上７０％以下である請求項１０又は１１に記載のグラファイトシートの製造方法。 In the solution or suspension in the first step, the weight ratio of the plurality of graphite particles to the solid content of the graphene oxide and the total amount of the plurality of graphite particles is 1% or more and 70% or less. A method for producing a graphite sheet as described in .
PCT/JP2023/030358 2022-08-31 2023-08-23 Graphite sheet, and method for producing same WO2024048396A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005019132A1 (en) * 2003-08-26 2005-03-03 Matsushita Electric Industrial Co., Ltd. Highly heat-conductive member, method for producing same, and heat dissipating system using same
WO2015045641A1 (en) * 2013-09-26 2015-04-02 株式会社カネカ Graphite sheet, method for producing same, laminated board for wiring, graphite wiring material, and method for producing wiring board
US20190075683A1 (en) * 2016-09-13 2019-03-07 Huawei Technologies Co., Ltd. Heat sink, preparation method therefor, and communications device
JP2019206447A (en) * 2016-09-30 2019-12-05 コニカミノルタ株式会社 Method of producing graphite molding
JP2022511459A (en) * 2018-11-30 2022-01-31 ピーアイ・アドバンスド・マテリアルズ・カンパニー・リミテッド Graphite sheet manufactured from polyimide film with excellent orientation and its manufacturing method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005019132A1 (en) * 2003-08-26 2005-03-03 Matsushita Electric Industrial Co., Ltd. Highly heat-conductive member, method for producing same, and heat dissipating system using same
WO2015045641A1 (en) * 2013-09-26 2015-04-02 株式会社カネカ Graphite sheet, method for producing same, laminated board for wiring, graphite wiring material, and method for producing wiring board
US20190075683A1 (en) * 2016-09-13 2019-03-07 Huawei Technologies Co., Ltd. Heat sink, preparation method therefor, and communications device
JP2019206447A (en) * 2016-09-30 2019-12-05 コニカミノルタ株式会社 Method of producing graphite molding
JP2022511459A (en) * 2018-11-30 2022-01-31 ピーアイ・アドバンスド・マテリアルズ・カンパニー・リミテッド Graphite sheet manufactured from polyimide film with excellent orientation and its manufacturing method

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