JP6705325B2 - COMPOSITE PARTICLE FOR HEAT CONDUCTIVE SHEET, PROCESS FOR PRODUCING THE SAME, METHOD FOR PRODUCING HEAT CONDUCTIVE PRIMARY SHEET AND HEAT CONDUCTIVE SECONDARY SHEET, METHOD FOR PRODUCING HEATING BODY WITH HEAT CONDUCTIVE PRIMARY SHEET, AND METHOD FOR PRODUCING HEATING BODY WITH LAMINATED SHEET - Google Patents

Description

The present invention is a composite particle for a heat conductive sheet, a method for manufacturing a composite particle for a heat conductive sheet, a method for manufacturing a heat conductive primary sheet, a method for manufacturing a heat conductive secondary sheet, a method for manufacturing a heating element with a heat conductive primary sheet, and a laminate. The present invention relates to a method for manufacturing a heating element with a sheet.

2. Description of the Related Art In recent years, electronic components such as plasma display panels (PDP) and integrated circuit (IC) chips have increased the amount of heat generation as their performance has increased. As a result, in an electronic device using an electronic component, it is necessary to take measures for a functional failure due to a temperature rise of the electronic component.

As a measure against functional failure due to temperature rise of electronic parts, generally, a method of accelerating heat dissipation by attaching a heat sink such as a metal heat sink, heat sink, or heat dissipation fin to a heat generator such as an electronic part is adopted. ing. In addition, when using the heat radiator, in order to efficiently transfer the heat from the heat generator to the heat radiator, the heat generator is connected to the heat generator through a sheet-shaped member (heat conductive sheet) that exhibits good thermal conductivity. It is in close contact with the radiator. The heat conductive sheet provided between the heat generating element and the heat radiating element is required to have high heat conductivity in the thickness direction.

Further, from the viewpoint of uniformizing and dissipating the heat of the heating element, heat dissipation from the heating element can be achieved by adhering a heat conductive sheet having a high thermal conductivity in the in-plane direction to the heating element without using a radiator. It is also being promoted. Further, heat dissipation is also improved by sequentially laminating a sheet having a high thermal conductivity in the in-plane direction, a sheet having a high thermal conductivity in the thickness direction, and a radiator for the heating element. ..

Here, as the heat conductive sheet, a sheet formed by using a composite mixture in which a resin and a component exhibiting heat conductivity are mixed is usually used.

Therefore, in recent years, in order to improve the thermal conductivity of the heat conductive sheet, attempts have been made to improve the composite mixture used for forming the heat conductive sheet.

For example, in Patent Document 1, by applying a pressure to a composition obtained by kneading a thermally conductive inorganic material containing flake graphite and an organic polymer compound, the surface direction of the flake of the inorganic material is a main surface. A primary sheet oriented in a direction substantially parallel thereto is formed. Further, in Patent Document 1, after stacking a plurality of the obtained primary sheets in the thickness direction to form a laminated body, the laminated body is sliced in the laminating direction, and the sliced laminated body is roll-pressed. A heat conductive sheet is formed in which the surface directions of the scales of the inorganic material are oriented with an inclination of 5° to 60° with respect to the thickness direction of the sheet. In the heat conductive sheet of Patent Document 1, the thermal conductivity in the thickness direction is improved by orienting the inorganic material.

JP, 2005-84431, A

However, the heat-conducting sheet of Patent Document 1 has room for improvement in further improving the heat conductivity, particularly in further improving the heat conductivity in a desired direction.

Therefore, the present invention provides a method for producing a heat conductive sheet capable of producing a heat conductive primary sheet having excellent thermal conductivity in the in-plane direction and a heat conductive secondary sheet having excellent thermal conductivity in the thickness direction. To aim.
Further, the present invention is a composite particle for a heat conductive sheet that can be used for producing a heat conductive primary sheet having excellent heat conductivity in the in-plane direction and a heat conductive secondary sheet having excellent heat conductivity in the thickness direction, and An object of the present invention is to provide a method for producing composite particles for a heat conductive sheet, which can prepare the composite particles.
A further object of the present invention is to provide a method for producing a heat-conducting primary sheet-equipped heating element and a laminated sheet-provided heating element having excellent heat dissipation characteristics.
In the present invention, the term "heat conductive sheet" simply means a heat conductive primary sheet and/or a heat conductive secondary sheet.

The present inventors have earnestly studied to achieve the above object. Then, the inventors of the present invention used a composite particle containing a resin and a particulate carbon material and having an SE value within a predetermined range to obtain a heat conductive sheet (heat conductive sheet) having excellent thermal conductivity in the in-plane direction. It was found that a primary sheet) and a thermal conductive sheet (thermally conductive secondary sheet) having excellent thermal conductivity in the thickness direction can be manufactured. Further, the present inventors can produce a heat generating element with a heat conductive primary sheet and a heat generating element with a laminated sheet, which are excellent in heat dissipation characteristics from a heat generating element, by using the heat conductive primary sheet and the heat conductive secondary sheet. It was found that the present invention has been completed.

That is, this invention aims at solving the above-mentioned subject advantageously, and the composite particle for heat conductive sheets of this invention contains a particulate carbon material and resin, SE value is 6.0 mJ/g. It is characterized in that it is 16.0 mJ/g or less. When the composite particles for a heat conductive sheet contain a particulate carbon material and a resin and have an SE value within a predetermined range, a heat conductive sheet excellent in heat conductivity in a desired direction such as an in-plane direction and a thickness direction can be obtained. can get.
In addition, in this invention, "SE value" points out a Specific Energy value (specific energy value), and means the energy per mass (mJ/g) required in order to make the composite particle for heat conductive sheets flow. In the present invention, the “SE value” can be measured and calculated at 25° C. using a powder fluidity analyzer according to the method described in Examples of the present specification.

Here, in the composite particle for a heat conductive sheet of the present invention, the content ratio of the particulate carbon material is preferably 40% by volume or more. If the content ratio of the particulate carbon material in the composite particles for the heat conductive sheet is at least the above lower limit, the heat conductivity in the desired direction of the heat conductive sheet produced using the composite particles for the heat conductive sheet is more excellent. Is.

Moreover, in the composite particle for a heat conductive sheet of the present invention, the particulate carbon material is preferably expanded graphite. This is because if the composite particles for a heat conductive sheet include expanded graphite, the heat conductivity of the heat conductive sheet manufactured using the composite particles for a heat conductive sheet is further excellent in a desired direction.

And in the composite particle for heat conductive sheets of this invention, it is preferable that the said resin is a thermoplastic resin. This is because if the composite particles for a heat conductive sheet include a thermoplastic resin, a heat conductive sheet having excellent heat conductivity in a desired direction such as an in-plane direction and a thickness direction can be easily obtained. In addition, if the composite particles for a heat conductive sheet include a thermoplastic resin, the obtained heat conductive sheet exhibits high flexibility in a high temperature environment during use (at the time of heat dissipation), and thus has a space between the heat conductive sheet and a heating element. This is because it is possible to improve the adhesiveness of, and it is possible to improve the heat dissipation from the heating element.

Moreover, this invention aims at solving the said subject advantageously, The manufacturing method of the composite particle for heat conductive sheets of this invention prepares the composite mixture containing a particulate carbon material and resin. A step of pulverizing the composite mixture to obtain composite particles having an SE value of 6.0 mJ/g or more and 16.0 mJ/g or less. If composite particles having a predetermined SE value obtained by pulverizing a composite mixture containing a particulate carbon material and a resin are used as composite particles for a heat conductive sheet, heat in a desired direction such as an in-plane direction and a thickness direction can be obtained. A heat conductive sheet having excellent conductivity can be obtained.

Moreover, this invention aims at solving the said subject advantageously, and the manufacturing method of the heat conduction primary sheet of this invention is any one of the composite particles for heat conduction sheets mentioned above, or the above-mentioned manufacture. The method is characterized by including a step of pressurizing the composite particles for a heat conductive sheet obtained by the method to form a sheet. If a heat-conducting primary sheet is produced by press-molding a predetermined composite particle for a heat-conducting sheet into a sheet, it is possible to obtain a heat-conducting sheet having excellent heat conductivity in a desired direction, particularly in the in-plane direction of the sheet. it can.

Further, the present invention is intended to advantageously solve the above problems, the manufacturing method of the heat conductive secondary sheet of the present invention, the heat conductive primary sheet obtained by the above-described manufacturing method in the thickness direction. A plurality of layers, or by folding or winding the heat-conducting primary sheet obtained by the manufacturing method described above to obtain a laminate, and the laminate is formed at 45° or less with respect to the laminating direction. Slicing at an angle to obtain a heat conductive secondary sheet, and a slicing step. When the heat-conducting secondary sheet is manufactured by using the predetermined heat-conducting primary sheet according to the above steps, it is possible to obtain a heat-conducting sheet having excellent heat conductivity in a desired direction, particularly in the sheet thickness direction.

The method for producing a heat-conducting primary sheet-equipped heating element of the present invention is characterized by including a step of adhering the heat-conducting primary sheet obtained by the above-described manufacturing method to at least one surface of the heating element. If the heat-conducting primary sheet of the present invention is adhered to the surface of the heat-generating body, the heat from the heat-generating body is efficiently transferred mainly in the in-plane direction of the heat-conducting primary sheet, so that the heat-generating body can radiate heat well. .. That is, it is possible to obtain a heating element with a heat conduction primary sheet having excellent heat dissipation characteristics.

Further, the method for producing a heating element with a laminated sheet of the present invention, on at least one surface of the heating element, a heat conduction primary sheet obtained by the above-mentioned production method and a heat conduction secondary sheet obtained by the above-mentioned production method. It is characterized by including a step of adhering the laminated sheet having. If a laminated sheet having the heat-conducting primary sheet of the present invention and the heat-conducting secondary sheet of the present invention is adhered to the surface of the heating element, heat from the heating element is efficiently transferred to the laminated sheet, so that the heating element is good. Can dissipate heat. That is, it is possible to obtain a heating element with a laminated sheet having excellent heat dissipation characteristics.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the heat conductive sheet which can manufacture the heat conductive primary sheet excellent in the heat conductivity in the in-plane direction and the heat conductive secondary sheet excellent in the heat conductivity in the thickness direction can be provided. it can.
Further, according to the present invention, a composite particle for a heat conductive sheet that can be used for producing a heat conductive primary sheet having excellent heat conductivity in the in-plane direction and a heat conductive secondary sheet having excellent heat conductivity in the thickness direction. It is also possible to provide a method for producing composite particles for a heat conductive sheet, which is capable of preparing the composite particles.
Further, according to the present invention, it is possible to provide a method of manufacturing a heat-conducting primary sheet-equipped heating element and a laminated sheet-equipped heating element having excellent heat dissipation characteristics.

Hereinafter, the present invention will be described in detail based on its embodiments.
The composite particles for a heat conductive sheet of the present invention can be produced, for example, according to the method for producing a composite particle for a heat conductive sheet of the present invention, and can be used when producing a heat conductive sheet.
Further, the method for producing a heat conductive primary sheet and the method for producing a heat conductive secondary sheet of the present invention, for example, using the composite particles for a heat conductive sheet of the present invention, may be used when producing a heat conductive sheet. it can. Then, the heat conductive primary sheet obtained by the method for producing the heat conductive primary sheet of the present invention and the heat conductive secondary sheet obtained by the method for producing the heat conductive secondary sheet of the present invention are, for example, directly bonded to a heating element. It can be used, or can be used by sandwiching it between the heating element and the radiator when attaching the radiator to the heating element. At this time, the heat conductive primary sheet and the heat conductive secondary sheet may be used alone or in combination of two or more. Specifically, for example, the heat-conducting primary sheet obtained by the manufacturing method of the present invention may be used to configure the heat-generating body with the heat-conducting primary sheet of the present invention together with the heat-generating body. Further, for example, a laminated sheet in which the heat-conducting primary sheet and the heat-conducting secondary sheet obtained by the manufacturing method of the present invention are laminated may be used to configure the heating element with the laminated sheet of the present invention together with the heating element. In addition, the heat-conducting primary sheet and the heat-conducting secondary sheet obtained by the manufacturing method of the present invention can constitute a heat-dissipating device together with a heat-generating body and a heat-dissipating body such as a heat sink, a heat-dissipating plate, or a heat-dissipating fin.
The heat-conducting primary sheet-equipped heating element can be produced, for example, by using the method for producing a heat-conducting primary sheet-equipped heating element of the present invention. It can be manufactured using the method for manufacturing a heating element.

(Composite particles for heat conductive sheet)
The heat conductive sheet composite particles of the present invention are characterized by containing a particulate carbon material and a resin and having an SE value of 6.0 mJ/g or more and 16.0 mJ/g or less. When the composite particles for a heat conductive sheet do not contain the particulate carbon material, the heat conductive sheet obtained by using the composite particles cannot be provided with sufficient thermal conductivity. Further, when the composite particles for a heat conductive sheet do not contain a resin, the heat conductive sheet obtained using the composite particles cannot be provided with sufficient flexibility, and heat transfer from the heating element to the heat conductive sheet is not possible. Is insufficient. Then, if the SE value of the composite particles for a heat conductive sheet is not within the above-mentioned predetermined range, the particulate carbon material in the heat conductive sheet obtained by using the composite particles is favorably oriented, and the in-plane direction is formed on the heat conductive sheet. In addition, it is not possible to exhibit high thermal conductivity in a desired direction such as the thickness direction.

<Composition>
[Particulate carbon material]
Here, the particulate carbon material contained in the composite particles for the heat conductive sheet of the present invention is not particularly limited, and examples thereof include artificial graphite, scaly graphite, exfoliated graphite, natural graphite, acid-treated graphite, and expandability. Graphite such as graphite and expanded graphite; carbon black; and the like can be used. These may be used alone or in combination of two or more.
Of these, expanded graphite is preferably used as the particulate carbon material. This is because the use of expanded graphite can improve the thermal conductivity of the heat conductive sheet.

[[Expanded graphite]]
Here, the expanded graphite that can be preferably used as the particulate carbon material is, for example, expandable graphite obtained by chemically treating graphite such as flake graphite with sulfuric acid or the like, and then heat-expanded to obtain fine graphite. Can be obtained. Examples of the expanded graphite include EC1500, EC1000, EC500, EC300, EC100, and EC50 (all are trade names) manufactured by Ito Graphite Industry Co., Ltd.

[[Properties of particulate carbon material]]
Here, the particle diameter of the particulate carbon material contained in the composite particles for a heat conductive sheet of the present invention is preferably 100 μm or more in volume standard mode diameter, more preferably 150 μm or more, and 300 μm or less. Is preferable, and 250 μm or less is more preferable. If the particle diameter of the particulate carbon material is at least the above lower limit, the particulate carbon materials contact each other in the heat conductive sheet obtained using the composite particles to form a good heat transfer path, so that the heat conductive sheet This is because higher heat conductivity can be exhibited. Further, if the particle diameter of the particulate carbon material is not more than the above upper limit, the heat conducting sheet obtained by using the composite particles is given more flexibility, and the heat conducting sheet to the heat conducting sheet when contacted with the heating element is provided. This is because the heat transfer can be improved.
Further, the aspect ratio (major axis/minor axis) of the particulate carbon material contained in the composite particles for a heat conductive sheet of the present invention is preferably 1 or more and 10 or less, and more preferably 1 or more and 5 or less. preferable.

In the present invention, the “volume standard mode diameter” can be obtained by using a laser diffraction/scattering type particle size distribution measuring apparatus according to the method described in the examples of the present specification.
Further, in the present invention, the “aspect ratio of the particulate carbon material” is the particulate carbon material obtained by dissolving and removing the resin in the composite particles for a heat conductive sheet in a solvent, and observing the particulate carbon material with a SEM (scanning electron microscope). Then, for any 50 particulate carbon materials, the maximum diameter (major axis) and the particle diameter (minor axis) in the direction orthogonal to the maximum diameter are measured, and the ratio of the major axis and the minor axis (major axis/minor axis). It can be obtained by calculating the average value of.

[[Particulate carbon material content]]
The content ratio of the particulate carbon material in the composite particles for a heat conductive sheet of the present invention is preferably 40% by volume or more, more preferably 45% by volume or more, and 60% by volume or less. Is preferable, and 55% by volume or less is more preferable. If the content ratio of the particulate carbon material in the composite particles for a heat conductive sheet is not less than the above lower limit, the particulate carbon materials in the heat conductive sheet obtained by using the composite particles are more in contact with each other to achieve good heat transfer. Form a path. As a result, the heat conductive sheet can exhibit higher heat conductivity in the desired direction. Further, if the content ratio of the particulate carbon material is at most the above upper limit, the heat conductive sheet obtained by using the composite particles is given more flexibility, and the heat conductive sheet from the heat generating element to the heat conductive sheet when contacted with the heat generating element is provided. This is because it is possible to further improve the heat transfer and it is possible to sufficiently prevent the powdery particulate carbon material from falling off. Further, when the content ratio of the particulate carbon material in the composite particles for a heat conductive sheet is within the above range, the composite particles are likely to be subjected to a force due to pressure such as roll rolling, and as a result, in the heat conductive sheet. This is because the particulate carbon material can be better oriented in the desired direction.
In the present invention, the “content ratio (volume %)” can be obtained as a theoretical value according to the method described in the examples of the present specification.

[Fibrous carbon material]
The composite particles for a heat conductive sheet of the present invention may optionally further contain a fibrous carbon material. The optionally contained fibrous carbon material is not particularly limited, and for example, carbon nanotubes, vapor grown carbon fibers, carbon fibers obtained by carbonizing organic fibers, and cut products thereof can be used. You can These may be used alone or in combination of two or more.
When the composite particles for a heat conductive sheet of the present invention contain a fibrous carbon material, it is possible to further improve the thermal conductivity of the heat conductive sheet obtained by using the composite particles, and also the particulate carbon material. It is also possible to prevent the powder from falling off. The reason why the powdery carbon material can be prevented from falling off by blending the fibrous carbon material is not clear. However, the fibrous carbon material forms a three-dimensional network structure to improve thermal conductivity. It is presumed that this is because the desorption of the particulate carbon material is prevented while increasing the strength and strength.

Among the above, as the fibrous carbon material, it is preferable to use fibrous carbon nanostructures such as carbon nanotubes, and it is more preferable to use fibrous carbon nanostructures containing carbon nanotubes. This is because the use of fibrous carbon nanostructures such as carbon nanotubes can further improve the thermal conductivity and strength of the heat conductive sheet obtained by using the composite particles for a heat conductive sheet.

[[Fibrous carbon nanostructure containing carbon nanotubes]]
Here, the fibrous carbon nanostructure containing carbon nanotubes, which can be preferably used as the fibrous carbon material, may be composed of only carbon nanotubes (hereinafter, may be referred to as “CNT”). Alternatively, it may be a mixture of CNT and a fibrous carbon nanostructure other than CNT.
The CNTs in the fibrous carbon nanostructure are not particularly limited, and single-walled carbon nanotubes and/or multi-walled carbon nanotubes can be used. Nanotubes are preferable, and single-walled carbon nanotubes are more preferable. This is because the use of single-walled carbon nanotubes can further improve the thermal conductivity and strength of the heat-conductive sheet obtained by using the composite particles for a heat-conductive sheet, as compared with the case of using multi-walled carbon nanotubes. ..

Further, as a fibrous carbon nanostructure containing CNTs, the ratio (3σ/Av) of the value (3σ) obtained by multiplying the standard deviation (σ) of the diameter by 3 with respect to the average diameter (Av) is more than 0.20. It is preferable to use a carbon nanostructure of less than 0.60, more preferably to use a carbon nanostructure having 3σ/Av of more than 0.25, and to use a carbon nanostructure of 3σ/Av of more than 0.50. More preferably. If a fibrous carbon nanostructure containing CNTs with 3σ/Av of more than 0.20 and less than 0.60 is used, composite particles for a heat conductive sheet can be used even if the amount of the carbon nanostructure is small. This is because the heat conductivity and strength of the heat conductive sheet obtained as a result can be sufficiently enhanced. Therefore, it is possible to suppress an increase in the hardness of the heat conductive sheet (that is, a decrease in flexibility) due to the incorporation of the fibrous carbon nanostructure containing CNT, and to sufficiently improve the heat conductivity and flexibility of the heat conductive sheet. This is because they can be placed side by side at a high level.
The “average diameter of the fibrous carbon nanostructure (Av)” and the “standard deviation of the diameter of the fibrous carbon nanostructure (σ: sample standard deviation)” were measured using a transmission electron microscope. The diameter (outer diameter) of 100 randomly selected fibrous carbon nanostructures can be measured and obtained. Then, the average diameter (Av) and standard deviation (σ) of the fibrous carbon nanostructures containing CNTs are adjusted by changing the manufacturing method and the manufacturing conditions of the fibrous carbon nanostructures containing CNTs. Alternatively, it may be adjusted by combining a plurality of fibrous carbon nanostructures containing CNT obtained by different production methods.

As the fibrous carbon nanostructure containing CNT, the diameter measured as described above is plotted on the horizontal axis and the frequency is plotted on the vertical axis, and a normal distribution is obtained when approximated by Gaussian. Things are usually used.

Further, the fibrous carbon nanostructure containing CNT preferably has a peak of Radial Breathing Mode (RBM) when evaluated using Raman spectroscopy. It should be noted that RBM does not exist in the Raman spectrum of the fibrous carbon nanostructure composed of only multi-walled carbon nanotubes of three or more layers.

The average diameter (Av) of the fibrous carbon nanostructure containing CNT is preferably 0.5 nm or more, more preferably 1 nm or more, preferably 15 nm or less, and 10 nm or less. More preferably, This is because if the average diameter (Av) of the fibrous carbon nanostructures is 0.5 nm or more, aggregation of the fibrous carbon nanostructures can be suppressed and the dispersibility of the carbon nanostructures can be enhanced. .. Further, when the average diameter (Av) of the fibrous carbon nanostructure is 15 nm or less, the thermal conductivity and strength of the thermal conductive sheet obtained by using the composite particles for a thermal conductive sheet can be sufficiently increased. Is.

Furthermore, the BET specific surface area of the fibrous carbon nanostructure containing CNT is preferably 600 m ² /g or more, more preferably 800 m ² /g or more, and 2500 m ² /g or less. It is more preferably 1200 m ² /g or less. Furthermore, when the CNTs in the fibrous carbon nanostructure are mainly open, the BET specific surface area is preferably 1300 m ² /g or more. If the BET specific surface area of the fibrous carbon nanostructure containing CNTs is 600 m ² /g or more, the thermal conductivity and strength of the thermal conductive sheet obtained by using the composite particles for a thermal conductive sheet can be sufficiently increased. Because you can. Further, when the BET specific surface area of the fibrous carbon nanostructure containing CNT is 2500 m ² /g or less, aggregation of the fibrous carbon nanostructure is suppressed and the dispersibility of CNT in the heat conductive sheet is enhanced. Because you can.
In addition, in this invention, "BET specific surface area" refers to the nitrogen adsorption specific surface area measured using the BET method.

The fibrous carbon nanostructure containing CNTs having the above-described properties is obtained by, for example, supplying a raw material compound and a carrier gas onto a base material having a catalyst layer for producing carbon nanotubes on the surface thereof and chemically vaporizing it. When CNTs are synthesized by the phase growth method (CVD method), a small amount of an oxidant (catalyst activating substance) is present in the system to dramatically improve the catalytic activity of the catalyst layer (super growth method). ; International Publication No. 2006/011655), and can be efficiently produced. Note that, hereinafter, the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.

Here, the fibrous carbon nanostructure containing CNTs produced by the super growth method may be composed only of SGCNT, or in addition to SGCNT, for example, other non-cylindrical carbon nanostructures or the like. Carbon nanostructures may be included.

[[Properties of fibrous carbon material]]
The average fiber diameter of the fibrous carbon material that can be included in the heat conductive sheet is preferably 1 nm or more, more preferably 3 nm or more, preferably 2 μm or less, and 1 μm or less. More preferable. If the average fiber diameter of the fibrous carbon material is within the above range, the thermal conductivity, flexibility and strength of the thermal conductive sheet obtained by using the composite particles for a thermal conductive sheet can be juxtaposed at a sufficiently high level. Because.
Here, the aspect ratio of the fibrous carbon material is preferably more than 10.

In the present invention, the "average fiber diameter" means the fibrous carbon material obtained by dissolving and removing the resin in the composite particles for a heat conductive sheet in a solvent, which is SEM (scanning electron microscope) or TEM (transmission electron). It can be determined by observing with a microscope), measuring the fiber diameters of 50 arbitrary fibrous carbon materials, and calculating the number average value of the measured fiber diameters. In particular, when the fiber diameter is small, it is preferable to observe the same cross section with a TEM (transmission electron microscope).
Further, in the present invention, the “aspect ratio of fibrous carbon material” means that the fibrous carbon material obtained by dissolving and removing the resin in the composite particles for a heat conductive sheet is observed with a TEM (transmission electron microscope) For 50 fibrous carbon materials, the maximum diameter (major axis) and the particle diameter (minor axis) in the direction orthogonal to the maximum diameter were measured, and the average value of the ratio of the major axis and the minor axis (major axis/minor axis) was calculated. It can be calculated.

[resin]
Here, the resin contained in the composite particles for a heat conductive sheet of the present invention is not particularly limited, and a known resin that can be used for manufacturing a heat conductive sheet, for example, a thermoplastic resin or a thermosetting resin is used. You can Above all, it is preferable to use a thermoplastic resin for the composite particles for a heat conductive sheet of the present invention. If a thermoplastic resin is used, the flexibility of the heat-conducting sheet can be further improved in a high temperature environment during use (when radiating heat), and the heat-conducting sheet and the heat-generating body or the heat-generating body and the heat-radiating body can be radiated through the heat-conducting sheet. This is because it is possible to make good contact with the body.
In the present invention, rubber and elastomer are included in “resin”.

[[Thermoplastic resin]]
Known thermoplastic resins that can be used for manufacturing the heat conductive sheet include thermoplastic resins that are solid at room temperature and atmospheric pressure, and liquid thermoplastic resins at room temperature and atmospheric pressure. Among them, in the composite particles for the heat conductive sheet of the present invention, as the thermoplastic resin, it is preferable to use a solid thermoplastic resin under normal temperature and normal pressure, and it is more preferable to use a solid thermoplastic fluororesin under normal temperature and normal pressure. .. If a solid thermoplastic resin is used at room temperature and normal pressure, under the high temperature environment during use (heat dissipation), the flexibility of the heat conductive sheet obtained by using the composite particles will be further improved, and the heat conductive sheet and heat generation will be improved. This is because it is possible to improve the handleability of the heat conductive sheet in a room temperature environment such as when it is attached, while making the body better adhere to it. Further, if the thermoplastic resin that is solid at room temperature and atmospheric pressure is a thermoplastic fluororesin, in addition to the above effects, the heat resistance, oil resistance, and chemical resistance of the heat conductive sheet can be improved.
In addition, in this specification, "normal temperature" refers to 23° C., and "normal pressure" refers to 1 atm (absolute pressure).

− Thermoplastic resin that is solid under normal temperature and pressure −
Here, as the thermoplastic resin which is solid under normal temperature and normal pressure, for example, poly(2-ethylhexyl acrylate), copolymer of acrylic acid and 2-ethylhexyl acrylate, polymethacrylic acid or its ester, polyacrylic acid Or acrylic resin such as ester thereof; silicone resin; fluorine resin; polyethylene; polypropylene; ethylene-propylene copolymer; polymethylpentene; polyvinyl chloride; polyvinylidene chloride; polyvinyl acetate; ethylene-vinyl acetate copolymer; polyvinyl Alcohol; polyacetal; polyethylene terephthalate; polybutylene terephthalate; polyethylene naphthalate; polystyrene; polyacrylonitrile; styrene-acrylonitrile copolymer; acrylonitrile-butadiene copolymer (nitrile rubber); acrylonitrile-butadiene-styrene copolymer (ABS resin) Styrene-butadiene block copolymer or hydrogenated product thereof; styrene-isoprene block copolymer or hydrogenated product thereof; polyphenylene ether; modified polyphenylene ether; aliphatic polyamides; aromatic polyamides; polyamideimide; polycarbonate; polyphenylene Sulfide; polysulfone; polyether sulfone; polyether nitrile; polyether ketone; polyketone; polyurethane; liquid crystal polymer; ionomer; and the like. These may be used alone or in combination of two or more.

Among the above, the thermoplastic resin that is solid under normal temperature and normal pressure is preferably a thermoplastic fluororesin that is solid under normal temperature and normal pressure.
As the solid thermoplastic fluororesin at room temperature and atmospheric pressure, for example, vinylidene fluoride-based fluororesin, tetrafluoroethylene-propylene-based fluororesin, tetrafluoroethylene-purple orovinyl ether-based fluororesin, etc. are polymerized with a fluorine-containing monomer. The resulting elastomer may be mentioned. More specifically, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride, polychloro. Trifluoroethylene, ethylene-chlorofluoroethylene copolymer, tetrafluoroethylene-perfluorodioxole copolymer, polyvinyl fluoride, tetrafluoroethylene-propylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene Examples thereof include a copolymer, an acrylic modified product of polytetrafluoroethylene, an ester modified product of polytetrafluoroethylene, an epoxy modified product of polytetrafluoroethylene, and a silane modified product of polytetrafluoroethylene. Among these, from the viewpoint of processability, polytetrafluoroethylene, an acrylic modified product of polytetrafluoroethylene, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer. Is preferred.

In addition, examples of commercially available thermoplastic fluororesins that are solid at room temperature and atmospheric pressure include Daiel (registered trademark) G-300 series/G-700 series/G-7000 series (polyol addition) manufactured by Daikin Industries, Ltd. Sulfurized/vinylidene fluoride-hexafluoropropylene binary copolymer), Daier G-550 series/G-600 series (polyol vulcanized/vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer) , DAI-EL G-800 series (peroxide vulcanization/vinylidene fluoride-hexafluoropropylene binary copolymer), DAI-EL G-900 series (peroxide vulcanization/vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene 3) Original copolymer); KYNAR (registered trademark) series (vinylidene fluoride fluororesin), KYNAR FLEX (registered trademark) series (vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer) manufactured by ALKEMA A-100 (vinylidene fluoride-hexafluoropropylene binary copolymer) manufactured by Chemers Co., Ltd.; and the like.

− Thermoplastic resin that is liquid at room temperature and pressure −
Further, as long as the effect of the present invention is not significantly impaired, a solid thermoplastic resin at room temperature and atmospheric pressure and a liquid thermoplastic resin at room temperature and atmospheric pressure can be used in combination. Examples of the thermoplastic resin that is liquid at room temperature and normal pressure include acrylic resin, epoxy resin, silicone resin, and fluororesin. These may be used alone or in combination of two or more.

The viscosity of the thermoplastic resin that is liquid at room temperature and atmospheric pressure is not particularly limited, but from the viewpoint of good kneading property, fluidity, crosslinking reactivity, and excellent moldability, the viscosity at 105° C. is 500 mPa· s to 30,000 mPa·s is preferable, and 550 mPa·s to 25,000 mPa·s is more preferable.

[[Thermosetting resin]]
Examples of the thermosetting resin include natural rubber; butadiene rubber; isoprene rubber; nitrile rubber; hydrogenated nitrile rubber; chloroprene rubber; ethylene propylene rubber; chlorinated polyethylene; chlorosulfonated polyethylene; butyl rubber; halogenated butyl rubber; Polyisobutylene rubber; Epoxy resin; Polyimide resin; Bismaleimide resin; Benzocyclobutene resin; Phenol resin; Unsaturated polyester; Diallyl phthalate resin; Polyimide silicone resin; Polyurethane; Thermosetting polyphenylene ether; Thermosetting modified polyphenylene ether; Is mentioned. These may be used alone or in combination of two or more.

[[Moonie viscosity]]
The resin contained in the composite particles for a heat conductive sheet of the present invention (a resin mixture when two or more resins are used) preferably has a Mooney viscosity (ML ₁₊₄ , 100° C.) of 10 or more, and 15 The above is more preferable, 100 or less is preferable, 90 or less is more preferable, and 40 or less is further preferable. Generally, the lower the Mooney viscosity, the lower the stickiness of the resin, and the higher the Mooney viscosity, the higher the stickiness of the resin. Therefore, when a resin having a Mooney viscosity of not more than the above upper limit is used, the interaction such as the binding property between the composite particles for the heat conductive sheet is increased, and the SE value is also increased. As a result, the heat conductivity of the heat conductive sheet obtained by using the composite particles in a desired direction can be further increased. Further, if the Mooney viscosity is at least the above lower limit, it is possible to prevent the viscosity of the resin from becoming excessively low, and to easily manufacture the composite particles for a heat conductive sheet and the heat conductive sheet.
In addition, in the present specification, the “Moonie viscosity (ML ₁₊₄ , 100° C.)” can be measured at a temperature of 100° C. according to JIS K6383.

[[Resin content ratio]]
The content ratio of the resin in the composite particles for a heat conductive sheet of the present invention is preferably 30% by volume or more, more preferably 40% by volume or more, and further preferably 45% by volume or more. , 60% by volume or less, and more preferably 55% by volume or less. When the content ratio of the resin in the composite particles for a heat conductive sheet is at least the above lower limit, the heat conductive sheet obtained by using the composite particles has higher flexibility, and heat conduction from the heating element when contacted with the heating element. This is because heat transfer to the seat can be improved. Further, if the content ratio of the resin in the composite particles for a heat conductive sheet is not more than the above upper limit, the heat conductive sheet obtained by using the composite particles can exhibit higher heat conductivity.

[Additive]
If necessary, the composite particles for a heat conductive sheet of the present invention may be mixed with known additives that can be used for producing the heat conductive sheet. The additive that can be added to the heat conductive sheet is not particularly limited, and examples thereof include plasticizers such as fatty acid esters; flame retardants such as red phosphorus flame retardants and phosphoric acid ester flame retardants; fluorine oil ( (Demnum series manufactured by Daikin Industries, Ltd.) Additives that also serve as plasticizers and flame retardants; toughness improvers such as urethane acrylates; hygroscopic agents such as calcium oxide and magnesium oxide; silane coupling agents, titanium couplings And an adhesive agent such as an acid anhydride; a wettability improving agent such as a nonionic surfactant and a fluorine-containing surfactant; an ion trap agent such as an inorganic ion exchanger; and the like.

<Property>
[SE value]
The SE value of the composite particles for a heat conductive sheet of the present invention needs to be 6.0 mJ/g or more and 16.0 mJ/g or less. The SE value of the composite particles for a heat conductive sheet of the present invention is preferably 8.0 mJ/g or more, more preferably 10.0 mJ/g or more, and 15.5 mJ/g or less. Is preferred. When the SE value of the composite particles for a heat conductive sheet is within the above range, a heat conductive sheet having a high thermal conductivity in a desired direction such as an in-plane direction and a thickness direction can be manufactured using the composite particles. .. The thermal conductivity of the heat conductive sheet produced by using the composite particles for a heat conductive sheet having an SE value within the above predetermined range is not clear as to the reason why the heat conductivity increases in a desired direction, for example, the in-plane direction. It is supposed to be the street.
That is, generally, composite particles having a higher SE value are less likely to flow. Therefore, for example, the energy received when the composite particles are formed into a sheet by pressurization becomes larger as the composite particles having a higher SE value. Then, the particulate carbon material contained in the composite particles having received the larger energy is oriented in a direction (in-plane direction of the sheet) substantially orthogonal to the pressing direction. As a result, in the sheet obtained by pressing, the particulate carbon materials contact each other along the in-plane direction of the sheet, while forming a good heat transfer path particularly in the in-plane direction. That is, by manufacturing the heat conductive sheet using the composite particles having a SE value that is somewhat high, the heat conductivity of the obtained heat conductive sheet in the in-plane direction can be increased.
On the other hand, if the SE value of the composite particles is too high, the composite particles do not easily flow excessively. Therefore, for example, even if the composite particles are pressurized, each particle cannot uniformly receive large energy, and the particulate carbon materials contained in the composite particles are also aligned in one direction and well contacted. I can't. As a result, a good heat transfer path is not formed in the obtained sheet, and high heat conductivity cannot be exhibited as a heat conductive sheet.
Further, if the SE value of the composite particles is too low, the fluidity of the composite particles at the time of pressurization such as rolling becomes excessively high, so that the composite particles cannot sufficiently receive the energy due to the pressurization. Therefore, even if the composite particles are pressed, it cannot be formed into a sheet shape, or the obtained sheet does not have sufficient density and strength, is in a so-called messy state, and can be formed into a good sheet shape. I can't. As a result, the heat conductivity of the obtained sheet is low, and high heat conductivity cannot be exhibited as a heat conductive sheet.

The SE value of the composite particles for a heat conductive sheet can be controlled by adjusting the composition and morphology of the composite particles for a heat conductive sheet. Specifically, the SE value of the composite particles for a heat conductive sheet is, for example, the type, properties, and amount of the particulate carbon material and resin contained in the composite particles for a heat conductive sheet; the particle diameter of the composite particles for a heat conductive sheet. Can be appropriately controlled by adjusting Further, the SE value of the composite particles for a heat conductive sheet can be appropriately controlled by, for example, adjusting the pulverization conditions and classification conditions of the composite mixture in the step of obtaining the composite particles described below.

[Particle size]
When the particle size of the particle group of the composite particles for a heat conductive sheet is adjusted by performing a sieving method by a classification method described later, it is preferable to use a sieve with a mesh opening size of 100 μm or more. It is more preferable to adopt a sieving top of 150 μm or more, more preferably 1000 μm or less and a sieving bottom, 850 μm or less, more preferably a sieving bottom, and 500 μm or less to a sieving bottom. More preferable. If the particle size of the particle group of the composite particles for a heat conductive sheet is adjusted to be equal to or less than the above upper limit, the SE value is increased, and the particulate carbon material in the heat conductive sheet obtained by using the composite particles is better oriented. This is because the thermal conductivity in the desired direction is further increased. Further, if the particle size of the particle group of the composite particles for the heat conductive sheet is adjusted to the above lower limit or more, the particulate carbon materials contained in the composite particles are more preferable without making the particle size of the composite particles excessively small. This is because the contact can be made with a low interface resistance and a good heat transfer path can be secured.

(Method for producing composite particles for heat conductive sheet)
The method for producing composite particles for a heat conductive sheet of the present invention comprises a step of preparing a composite mixture containing a particulate carbon material and a resin, and pulverizing the obtained composite mixture to obtain an SE value within a predetermined range. And a step of obtaining Further, according to the method for producing a composite particle for a heat conductive sheet of the present invention, for example, the composite particle for a heat conductive sheet of the present invention described above can be obtained.

<Step of preparing complex mixture>
In the step of preparing the composite mixture, a composite mixture containing the particulate carbon material and the resin is prepared. Specifically, in the step of preparing the composite mixture, the particulate carbon material and the resin and any fibrous carbon material and/or the additive are compounded by a known method without particular limitation. You may prepare a complex mixture by. Further, in the step of preparing the composite mixture, it may be prepared by purchasing a commercially available composite mixture containing the particulate carbon material and the resin. In the case of preparing a composite mixture by forming the composite, more specifically, for example, the following methods (I) to (III) can be used.
(I) A particulate carbon material, a resin, and any fibrous carbon material and/or additive are mixed and kneaded to obtain a composite mixture.
(II) A dispersion liquid containing the particulate carbon material, the resin, and any fibrous carbon material and/or additive is dried and granulated to obtain a composite mixture.
(III) A resin or the like is sprayed on the particulate carbon material and any fibrous carbon material to obtain a composite mixture.
Above all, it is desirable to use the method (I) from the viewpoint of workability.
As the particulate carbon material, resin, optional fibrous carbon material and/or additive used in the step of preparing the composite mixture, the particulate carbon material, resin, or the like which the composite particles for the heat conductive sheet may include The same component as that of the fibrous carbon material and/or the additive can be used, and a suitable content ratio can be the same.

[Mixing and kneading method]
The method of mixing and kneading is not particularly limited, and a known mixing device such as a kneader, a roll, a Henschel mixer, or a Hobart mixer can be used. The mixing and kneading time can be, for example, 5 minutes or more and 6 hours or less. The mixing and kneading temperature can be, for example, 5°C or higher and 150°C or lower.
Here, the mixing and kneading may be performed in the presence of a solvent such as ethyl acetate, but when a solvent is used at the time of mixing and kneading, the solvent is removed prior to crushing/grinding of the composite mixture described below. It is preferable. Removal of the solvent may be carried out by a known drying method, or may be carried out while optionally degassing the complex mixture. For example, if defoaming is performed using vacuum defoaming, the solvent can be removed at the same time when defoaming.

[Complex mixture]
Then, the obtained composite mixture contains a particulate carbon material and a resin, and optionally further contains a fibrous carbon material and an additive. The composite mixture is usually a lump having a diameter of about 1 mm to 200 mm.

<Step of obtaining composite particles>
In the step of obtaining composite particles, the obtained composite mixture is pulverized by an arbitrary method to obtain composite particles. Further, in the step of obtaining composite particles, the obtained composite mixture may be pulverized and then classified by an arbitrary method to obtain composite particles. Then, the composite particles for a heat conductive sheet manufactured through the process of obtaining the composite particles need to have a predetermined SE value. If the composite particles for a heat conductive sheet do not have a predetermined SE value, the heat conductive sheet obtained using the composite particles should exhibit high heat conductivity in a desired direction such as an in-plane direction and a thickness direction. I can't.

[Crushing method]
The pulverization of the composite mixture is not particularly limited as long as the obtained composite particles are a powdered fluid rather than the lumps of the composite mixture, and can be performed by a known method. In addition, prior to the crushing, crushing to loosen the lumps may be performed. Then, the crushing/crushing of the composite mixture can be performed using, for example, a known crushing/crushing machine utilizing a shearing action or a grinding action, a known stirring-type crushing/crushing device, or the like. Examples of the known crusher/crusher described above include a hammer crusher, a cutter mill, a hammer mill, a bead mill, a vibration mill, a meteor type ball mill, a sand mill, a ball mill, a roll mill, a triple roll mill, a jet mill, and a high-speed rotary crusher. , A fine pulverizer/a crushing and sizing machine, a nano jet mizer, and the like.
The conditions such as the type of crushing/crushing machine, the energy for crushing/crushing, the time, etc. are appropriately selected according to the desired powdery fluid state such as the state of the lump of the composite mixture and the particle size of the composite particles, Adjust it.

Here, the composite mixture is preferably pulverized to a particle size of less than 1000 μm without particular limitation.

[Classification method]
In the step of obtaining the composite particles, after pulverizing the composite mixture, classification may be performed in order to obtain the composite particles by selecting the pulverized composite mixture into a particle group having a more desired particle size range. Here, the classification method is not particularly limited and includes, for example, a sieving method, a forced vortex type centrifugal classifier (micron separator, turboplex, turbo classifier, super separator), an inertial classifier (improved Vertuer. An airflow classifier such as an Alimpactor or an elbow jet) can be used. Further, a wet sedimentation method, a centrifugal classification method, etc. can also be used. Further, the classification may be carried out at the same time as the crushing/crushing work as one function of the crushing/crusher described above, or may be carried out separately from the crushing/crushing work. When it is carried out simultaneously with the crushing/crushing work, it can be carried out, for example, by installing a screen having a desired mesh size in the equipment used. Further, when it is carried out separately from the crushing/crushing work, for example, a sieving method having a desired opening can be carried out from the viewpoint of workability.
The classification temperature can be set to 25°C, for example.

<Composite particles for heat conductive sheet>
[SE value]
Then, the heat conductive sheet composite particles produced through the step of preparing the composite mixture and the step of obtaining the composite particles, that is, the heat conductive sheet composite particles obtained according to the method for producing the heat conductive sheet composite particles of the present invention, , The SE value must be 6.0 mJ/g or more and 16.0 mJ/g or less. Further, a suitable SE value of the composite particles for a heat conductive sheet obtained according to the method for producing a composite particle for a heat conductive sheet of the present invention and its effect are as follows: The effect is similar.

[Particle size]
Further, suitable particle size of the composite particles for the heat conductive sheet obtained according to the method for producing a composite particle for the heat conductive sheet of the present invention and its effect are also preferable particle size of the composite particles for the heat conductive sheet of the present invention described above and The effect can be similar.
Here, as described above, in particular, when the classification is performed in the step of obtaining the composite particles, the SE value of the composite particles for a heat conductive sheet increases as the particle size of the particle group of the composite particles after classification decreases to some extent. Therefore, the thermal conductivity of the heat conductive sheet obtained by using the composite particles also tends to increase. Thus, the reason why the SE value of the composite particles increases as the particle size of the particle group of the composite particles after classification increases to some extent is not clear, but mutual collision during pressurization occurs between composite particles having smaller particle sizes. It is speculated that this is because the liquidity decreases as a result of the increase in the liquidity.

(Method of manufacturing heat conduction primary sheet)
The method for producing a heat-conducting primary sheet of the present invention, any one of the above-mentioned composite particles for heat-conducting sheet, or the composite particles for heat-conducting sheet obtained by the above-mentioned method for producing composite particles for a heat-conducting sheet are pressed. It includes a step of forming into a sheet. The heat-conducting primary sheet obtained according to the method for producing a heat-conducting primary sheet of the present invention comprises a particulate carbon material and a resin, and presses the composite particles for a heat-conducting sheet having a predetermined SE value into a sheet shape. Since it is molded by, it has excellent thermal conductivity in the in-plane direction of the sheet (direction substantially orthogonal to the pressing direction).

<Process of pressing composite particles to form a sheet>
In the step of pressing the composite particles to form a sheet, any of the heat conductive sheet composite particles described above, or the heat conductive sheet composite particles obtained by the method for producing the heat conductive sheet composite particles described above may be used. A heat conductive primary sheet is obtained by pressurizing by the method of 1 to form a sheet.

[Pressure method]
The pressing method of the composite particles for a heat conductive sheet is not particularly limited as long as it is a molding method in which a pressure is applied. The composite particles for a heat conductive sheet can be molded into a sheet by using a known molding method such as press molding, rolling molding or extrusion molding. Above all, the composite particles for a heat conductive sheet are preferably formed into a sheet by roll forming, and more preferably formed into a sheet by passing between rolls while being sandwiched between protective films. The protective film is not particularly limited, and a sandblasted polyethylene terephthalate (PET) film or the like can be used. The roll temperature can be set to 5°C or higher and 150°C.

<Thermal conduction primary sheet>
Then, the heat-conducting primary sheet formed by pressing the composite particles for a heat-conducting sheet into a sheet shape is formed by using composite particles containing a particulate carbon material and a resin and having a predetermined SE value. Therefore, the particulate carbon material and any fibrous carbon material are mainly oriented in the in-plane direction of the sheet, and it is speculated that the thermal conductivity particularly in the in-plane direction is improved. Therefore, for example, by closely adhering the heat generating element and the heat conducting primary sheet, the heat generated from the heat generating element can be efficiently dissipated in the in-plane direction of the heat conducting primary sheet.

[Thermal conductivity]
Here, the thermal conductivity of the heat-conducting primary sheet in the in-plane direction is preferably 30 W/m·K or more at 25° C., more preferably 40 W/m·K or more, and 50 W/m·K. It is more preferable that the above is satisfied. This is because if the thermal conductivity of the heat-conducting primary sheet is at least the above lower limit, for example, when the heat-conducting primary sheet and the heating element are used in close contact with each other, heat can be efficiently dissipated from the heating element. .. Further, if the thermal conductivity of the thermal conductive primary sheet is equal to or higher than the lower limit, for example, when a thermal conductive secondary sheet is manufactured using the thermal conductive primary sheet as described later, the thermal conductive secondary sheet has a higher thermal conductivity. This is because the rate can be given.

[Thickness]
The thickness of the heat conduction primary sheet is not particularly limited and may be, for example, 0.05 mm or more and 2 mm or less. From the viewpoint of further improving the thermal conductivity of the heat-conducting primary sheet, the thickness of the heat-conducting primary sheet is preferably 5000 times or less the average particle diameter of the particulate carbon material.

(Method of manufacturing heat conductive secondary sheet)
The method for producing a heat conductive secondary sheet of the present invention is a method for producing a heat conductive sheet using the heat conductive primary sheet obtained according to the method for producing a heat conductive primary sheet of the present invention, to obtain a laminate described later. Including a process and a slice process. The heat conductive secondary sheet obtained according to the method for producing a heat conductive secondary sheet of the present invention is formed by undergoing a step of obtaining a laminate and a slicing step, and therefore, the thickness direction of the sheet (substantially orthogonal to the laminating direction) It has excellent thermal conductivity.

<Process of obtaining laminated body>
In the step of obtaining a laminate, a plurality of heat-conducting primary sheets obtained by the method for manufacturing a heat-conducting primary sheet described above are laminated in the thickness direction of the heat-conducting primary sheet, or the above-described heat-conducting primary sheet is manufactured. The heat conductive primary sheet obtained by the method is folded or wound to form a laminate.

[Lamination method]
The formation of the laminate by laminating the heat-conducting primary sheets is not particularly limited, and may be performed using a laminating apparatus or may be performed manually. Further, the formation of the laminate by folding the heat-conducting primary sheet is not particularly limited, and can be performed by folding the heat-conducting primary sheet with a constant width using a folding machine. Further, the formation of the laminate by winding the heat-conducting primary sheet is not particularly limited, by winding the heat-conducting primary sheet around an axis parallel to the lateral direction or the longitudinal direction of the heat-conducting primary sheet. It can be carried out.

Here, normally, in the step of obtaining a laminate, the adhesive force between the surfaces of the heat-conducting primary sheets is sufficiently obtained by the pressure when laminating the heat-conducting primary sheets and the pressure when folding or winding the heat-conducting primary sheets. However, when the adhesive strength is insufficient or when it is necessary to sufficiently suppress delamination of the laminate, the laminate may be formed with the surface of the heat-conducting primary sheet slightly dissolved with a solvent. Then, the laminate may be formed in a state in which an adhesive is applied to the surface of the heat-conducting primary sheet or in a state in which an adhesive layer is provided on the surface of the heat-conducting primary sheet.

The solvent used for dissolving the surface of the heat-conducting primary sheet is not particularly limited, and a known solvent capable of dissolving the resin component contained in the heat-conducting primary sheet can be used.

The adhesive applied to the surface of the heat-conducting primary sheet is not particularly limited, and a commercially available adhesive or tacky resin can be used. Above all, as the adhesive, it is preferable to use a resin having the same composition as the resin component contained in the heat conductive primary sheet. The thickness of the adhesive applied to the surface of the heat conductive primary sheet can be, for example, 10 μm or more and 1000 μm or less.
Further, the adhesive layer provided on the surface of the heat conductive primary sheet is not particularly limited, and a double-sided tape or the like can be used.

From the viewpoint of suppressing delamination, the obtained laminate is pressed at a pressure of 0.05 MPa or more and 1.0 MPa or less in the laminating direction while being pressed at 20° C. or more and 150° C. or less for 1 minute or more and 30 minutes or less. It is preferable to press.

In addition, in the laminated body obtained by laminating, folding or winding the heat conduction primary sheets, it is presumed that the particulate carbon material and any fibrous carbon material are oriented in a direction substantially orthogonal to the laminating direction.

<Slicing process>
In the slicing step, the heat conductive secondary sheet made of sliced pieces of the laminated body is obtained by slicing the laminated body obtained in the above step at an angle of 45° or less with respect to the laminating direction.

[Slicing method]
The method for slicing the laminate is not particularly limited, and examples thereof include a multi-blade method, a laser processing method, a water jet method, a knife processing method, and the like. Among them, the knife processing method is preferable because it is easy to make the thickness of the heat conductive secondary sheet uniform. Further, the cutting tool when slicing the laminate is not particularly limited, a smooth board surface having a slit, and a slicing member having a blade portion protruding from the slit portion (for example, a sharp blade is provided. Canna or slicer) can be used.

From the viewpoint of increasing the thermal conductivity of the heat conductive secondary sheet, the angle at which the laminate is sliced is preferably 30° or less with respect to the laminating direction and 15° or less with respect to the laminating direction. Is more preferable, and it is preferable that the angle is approximately 0° with respect to the stacking direction (that is, the direction is along the stacking direction).

Further, from the viewpoint of easily slicing the laminate, the temperature of the laminate during slicing is preferably −20° C. or higher and 40° C. or lower, and more preferably 10° C. or higher and 30° C. or lower. Furthermore, for the same reason, it is preferable to slice the laminated body while slicing while applying a pressure in a direction perpendicular to the laminating direction, and a pressure of 0.1 MPa or more and 0.5 MPa or less in the direction perpendicular to the laminating direction. It is more preferable to slice while loading.

<Secondary heat conduction sheet>
Then, as described above, the heat-conducting secondary sheet obtained according to the method for producing a heat-conducting secondary sheet of the present invention is molded through the step of obtaining a laminate and the slicing step, and therefore the particulate carbon material and any It is assumed that the fibrous carbon material is oriented in the thickness direction of the heat conductive secondary sheet. Therefore, for example, by closely adhering the heating element and the heat conducting secondary sheet, the heat generated from the heating element can be efficiently dissipated in the thickness direction of the heat conducting secondary sheet.

Further, a plurality of heat-conducting secondary sheets manufactured as described above may be further laminated in the thickness direction and integrated by allowing them to stand for a predetermined period of time to be used as the heat-conducting secondary sheet. .. In the heat conductive secondary sheet thus obtained, it is inferred that the particulate carbon material and any fibrous carbon material remain oriented in the thickness direction of the heat conductive secondary sheet. Therefore, by superimposing and integrating a plurality of heat conduction secondary sheets manufactured as described above in the thickness direction, the heat conduction of a desired thickness is performed according to the purpose of use without impairing the heat conductivity in the thickness direction. A secondary sheet can be obtained.

[Thickness]
Further, the thickness of the heat conductive secondary sheet is not particularly limited from the viewpoint of exhibiting high heat conductivity to the heat conductive secondary sheet, and may be, for example, 0.05 mm or more and 10 mm or less. Generally, if the thickness of the heat conductive sheet is too large, the thermal resistance of the heat conductive sheet increases, so the thermal conductivity decreases, and if the thickness of the heat conductive sheet is too small, the thermal conductivity of the heat conductive sheet is sufficient. This is because it cannot be used for.

(Use of heat conductive sheet)
The heat-conducting primary sheet and the heat-conducting secondary sheet obtained according to the production method of the present invention have excellent thermal conductivity, and usually also have excellent strength and electrical conductivity. Therefore, the heat-conducting primary sheet and the heat-conducting secondary sheet are, for example, heat-dissipating materials, heat-dissipating components, cooling components, temperature control components, electromagnetic wave shielding members, electromagnetic wave absorbing members, and objects to be pressure-bonded, which are used in various equipment and devices. It is suitable as a thermocompression-bonding rubber sheet to be interposed between the object to be pressure-bonded and the thermocompression-bonding device in the case of thermocompression bonding.
Here, the various devices and apparatuses are not particularly limited, and electronic devices such as servers, server personal computers, desktop personal computers; portable electronic devices such as notebook computers, electronic dictionaries, PDAs, mobile phones, portable music players, etc. Display devices such as liquid crystal display (including backlight), plasma display, LED, organic EL, inorganic EL, liquid crystal projector, clock; inkjet printer (ink head), electrophotographic device (developing device, fixing device, heat roller, Image forming devices such as heat belts; semiconductor elements, semiconductor packages, semiconductor encapsulation cases, semiconductor die bonding, CPU, memories, power transistors, power transistor cases, and other semiconductor-related parts; rigid wiring boards, flexible wiring boards, ceramic wiring Boards, build-up wiring boards, wiring boards such as multilayer boards (wiring boards include printed wiring boards, etc.); vacuum processing equipment, semiconductor manufacturing equipment, display equipment manufacturing equipment, etc. manufacturing equipment; heat insulating materials, vacuum heat insulating materials , Heat insulating device such as radiation heat insulating material; data recording device such as DVD (optical pickup, laser generator, laser light receiving device), hard disk drive; image recording of camera, video camera, digital camera, digital video camera, microscope, CCD, etc. Device: A battery device such as a charging device, a lithium ion battery, a fuel cell and the like can be mentioned.

(Method of manufacturing heat generating element with heat conduction primary sheet)
The method for producing a heat-conducting primary sheet-equipped heating element of the present invention includes a step of adhering the heat-conducting primary sheet obtained by the method for producing a heat-conducting primary sheet of the present invention to at least one surface of the heating element. Since the heat-conducting primary sheet-provided heating element obtained by the method for producing a heat-conducting primary sheet-providing heating element of the present invention includes the above-mentioned heat-conducting primary sheet, it can exhibit excellent heat dissipation characteristics. Specifically, in the heat-conducting primary sheet-equipped heating element obtained according to the method for producing a heat-conducting primary sheet-equipped heating element of the present invention, the heat generated from the heat-generating element is efficiently transferred mainly in the in-plane direction of the heat-conducting primary sheet. Can be dissipated into

Further, in the heat-conducting primary sheet-provided heating element obtained by the method for producing a heat-conducting primary sheet-providing heating element of the present invention, a known heat-dissipating body is further bonded to the surface of the heat-conducting primary sheet that is not in contact with the heat-dissipating element. can do. In other words, the heat-conducting primary sheet-provided heating element obtained according to the method for producing a heat-conducting primary sheet-provided heating element of the present invention includes a heat-dissipating device in which a heat-dissipating element and a heat-dissipating element are in close contact with each other via the heat-conducting primary sheet. It can form part. And since the said heat dissipation device is equipped with the heat generating body with a heat conductive primary sheet obtained according to the manufacturing method of the heat conductive primary sheet with a heat generating body of this invention, heat can be radiated favorably from a heat generating body to a heat sink. ..

<Step of adhering the heat conduction primary sheet>
In the step of adhering the heat-conducting primary sheet, the heat-conducting primary sheet obtained by the above-described method for producing the heat-conducting primary sheet is adhered to at least one surface of the heat-generating body to obtain a heat-conducting primary sheet-equipped heating element.

[Heating element]
The heating element is not particularly limited as long as it generates heat in various devices and devices such as electronic devices, and, for example, various devices and devices exemplified in the above-mentioned application of the heat conductive sheet, and these devices and devices have Examples include various heat generating parts.

[Adhesion method]
The method for adhering the heat conduction primary sheet to the heating element is not particularly limited, and a known method can be used.
Here, the surface of the heating element to which the heat-conducting primary sheet is adhered is not particularly limited, but from the viewpoint of more efficiently utilizing the thermal conductivity of the heat-conducting primary sheet, the temperature of the heating element becomes the highest. The surface is preferably close to the heat source site. From the viewpoint of more efficiently utilizing the thermal conductivity of the heat-conducting primary sheet, it is preferable to directly bond the heat-conducting primary sheet to the heating element, without using a medium such as an adhesive.
From the viewpoint of satisfactorily adhering the heat-conducting primary sheet and the heating element, it is preferable to fix the heat-conducting primary sheet and the heating element in a state where they are sufficiently adhered. From the viewpoint of maintaining good adhesiveness and the viewpoint of workability, as a bonding method, a method of bonding while applying pressure with an arbitrary force for an arbitrary time can be mentioned.
Then, the bonding temperature can be set to, for example, 10° C. or higher and 100° C. or lower.

(Method for manufacturing heating element with laminated sheet)
The method for producing a heating element with a laminated sheet of the present invention is a laminated sheet having a heat conduction primary sheet obtained by the above-mentioned production method and a heat conduction secondary sheet obtained by the above-mentioned production method on at least one surface of the heating element. Including the step of adhering. Here, the heating element may be in contact with the heat conduction primary sheet side of the laminated sheet, or may be in contact with the heat conduction secondary sheet side of the laminated sheet. In other words, the heating element with a laminated sheet obtained by the method for producing a heating element with a laminated sheet of the present invention has, for example, a structure in which a heating element/heat conduction primary sheet/heat conduction secondary sheet are bonded in this order. Alternatively, it may have a structure in which the heating element/heat conduction secondary sheet/heat conduction primary sheet are bonded in this order. The heat generating element with a laminated sheet obtained by the method for producing a heat generating element with a laminated sheet of the present invention includes the above-mentioned heat-conducting primary sheet and heat-conducting secondary sheet, and therefore can exhibit good heat dissipation characteristics. it can. Specifically, in the heating element with a laminated sheet obtained according to the method for producing a heating element with a laminated sheet of the present invention, the heat generated from the heating element is generated in any direction, mainly in the in-plane direction of the heat conduction primary sheet and The heat-conducting secondary sheet can be efficiently transmitted mainly in the thickness direction to be dissipated.

Further, in the heating element with a laminated sheet obtained by the method for producing a heating element with a laminated sheet of the present invention, a known radiator can be further adhered to the surface of the laminated sheet which is not in contact with the heating element. In other words, the heating element with a laminated sheet obtained according to the method for producing a heating element with a laminated sheet of the present invention has a heat dissipation element in which the heat dissipation element and the heat dissipation element are in close contact with each other via the heat conduction primary sheet and the heat conduction secondary sheet. It can form part of the device. Further, since the heat dissipation device includes the heat generating element with the laminated sheet obtained by the method for manufacturing the heat generating element with the laminated sheet of the present invention, heat can be satisfactorily radiated from the heat generating element to the heat radiating element.

<Step of adhering laminated sheets>
In the step of adhering the laminated sheet, on at least one surface of the heating element, the heat-conducting primary sheet obtained by the method for producing the heat-conducting primary sheet described above and the heat-conducting secondary sheet obtained by the method for producing the heat-conducting secondary sheet described above. A heating element with a laminated sheet is obtained by adhering a laminated sheet having a next sheet. Here, when adhering the laminated sheet to the heating element, for example, the heat conduction primary sheet and the heat conduction secondary sheet may be laminated in advance to form a laminated sheet, and the formed lamination sheet may be adhered to the heating element. The heat-conducting primary sheet or the heat-conducting secondary sheet may be first adhered to the heating element, and then the heat-conducting secondary sheet or the heat-conducting primary sheet may be adhered subsequently. Further, the laminated sheet may have one heat-conducting primary sheet and one heat-conducting secondary sheet, or may have a plurality of heat-conducting secondary sheets in any laminating order.

[Heating element]
The heating element is not particularly limited, and examples thereof include the same heating elements as those included in the heating element with the heat conduction primary sheet described above.

[Adhesion method]
The method for adhering the laminated sheet to the heating element is not particularly limited, and for example, the same method as the bonding method described in the method for manufacturing the heating element with the heat conduction primary sheet described above can be used.

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to these Examples. In addition, in the following description, “part” indicating the amount is based on mass unless otherwise specified.
Then, in Examples and Comparative Examples, the content ratio and the volume standard mode diameter of the particulate carbon material in the composite particles for a heat conductive sheet; the SE value of the composite particles for a heat conductive sheet; the thermal conductivity of the heat conductive primary sheet; , And measured and calculated using the following methods, respectively.

<Content ratio of particulate carbon material>
The theoretical value in volume fraction was used for the content rate of the particulate carbon material in the composite particles for a heat conductive sheet. Specifically, the density (g/cm ³ ) and the blending amount (g) of each component of the particulate carbon material, the resin, and the optional fibrous carbon material and the additive contained in the composite particles for the heat conductive sheet, The volume (cm ³ ) was calculated from the above, and the content ratio of the particulate carbon material in the composite particles for a heat conductive sheet was determined by the volume fraction (volume %).

<Volume-based mode diameter of particulate carbon material in composite particles for heat conductive sheet>
1 g of the composite particles for a heat conductive sheet was put into a methyl ethyl ketone solvent and the resin component was dissolved to obtain a suspension in which the particulate carbon material was separated and dispersed. Next, using the obtained suspension as a sample, the particle size of the particulate carbon material contained in the suspension was measured using a laser diffraction/scattering particle size distribution measuring device (manufactured by Horiba, Ltd., model “LA960”). Was measured. Then, the particle diameter at the maximum value of the particle diameter distribution curve with the obtained particle diameter as the horizontal axis and the volume of the particulate carbon material as the vertical axis was determined as the volume standard mode diameter (μm).

<SE value of composite particles for heat conductive sheet>
First, using a powder fluidity analyzer (manufactured by Sysmex Corporation, product name “Powder Rheometer FT4”, with two blades and a 200 ml container), the flow energy (mJ) of the composite particles for a heat conductive sheet was measured. The measured flow energy corresponds to the amount of work calculated from the torque and weight acting on the blade when the blade of the analyzer moves in the composite particles. Then, the SE value (mJ/g) of the composite particles for a heat conductive sheet was calculated by dividing the obtained flow energy by the mass (g) of the composite particles for a heat conductive sheet used for the measurement. The calculated SE value mainly reflects the work due to shearing, and the larger the SE value, the lower the fluidity of the composite particles for a heat conductive sheet.

<Thermal conductivity of the heat conduction primary sheet>
The thermal diffusivity α (m ² /s) in the in-plane direction, the constant pressure specific heat Cp (J/g·K) and the specific gravity ρ (g/m ³ ) of the heat conductive primary sheet were measured by the following methods.
[Thermal diffusivity α]
The thermal diffusivity at a temperature of 25° C. was measured using a thermophysical property measuring device (product name “Thermo Wave Analyzer TA35” manufactured by Bethel Co., Ltd.).
[Constant pressure specific heat Cp]
Using a differential scanning calorimeter (manufactured by Rigaku, product name “DSC8230”), the specific heat at a temperature of 25° C. was measured under a temperature rising condition of 10° C./min.
[Specific gravity ρ]
The specific gravity at a temperature of 25° C. was measured using an automatic densimeter (manufactured by Toyo Seiki Co., Ltd., product name “DENSIMTER-H”).
Then, using the obtained measured value, the following formula (I):
λ=α×Cp×ρ (I)
From the above, the thermal conductivity λ (W/m·K) of the heat conductive primary sheet at 25° C. was obtained.

(Example 1)
<Preparation of fibrous carbon nanostructure containing CNT>
A fibrous carbon nanostructure containing SGCNT was obtained by the super growth method as described in WO 2006/011655.
The BET specific surface area of the obtained fibrous carbon nanostructure was 800 m ² /g. The diameter of 100 randomly selected fibrous carbon nanostructures was measured using a transmission electron microscope. As a result, the average diameter (Av) was 3.3 nm, and the sample standard deviation (σ) was The value obtained by multiplying by 3 (3σ) was 1.9 nm, and their ratio (3σ/Av) was 0.58. Further, the obtained fibrous carbon nanostructure was mainly composed of single-walled CNT (also referred to as “SGCNT”).

<Preparation of easily dispersible aggregate of fibrous carbon nanostructures>
[Preparation of dispersion]
400 mg of the fibrous carbon nanostructure obtained above as a fibrous carbon material was weighed out, mixed in 2 L of methyl ethyl ketone as a solvent, and stirred for 2 minutes with a homogenizer to obtain a crude dispersion liquid. Next, using a wet jet mill (manufactured by Tsuneko Co., Ltd., product name “JN-20”), the obtained crude dispersion was passed through a 0.5 mm channel of the wet jet mill at a pressure of 100 MPa for 2 cycles. Then, the fibrous carbon nanostructure was dispersed in methyl ethyl ketone. Then, a dispersion liquid having a solid content concentration of 0.20 mass% was obtained.
[Removal of solvent]
Then, the dispersion liquid obtained above was filtered under reduced pressure using Kiriyama filter paper (No. 5A) to obtain a sheet-like easily dispersible aggregate.

<Production of composite particles for heat conductive sheet>
[Step of preparing complex mixture]
Expanded graphite as a particulate carbon material (Ito Graphite Industry Co., Ltd., trade name “EC-50”, average particle diameter: 250 μm), 130 parts, and an easily dispersible aggregate of carbon nanostructures as a fibrous carbon material. 1 part of the body and 80 parts of a thermoplastic fluororesin (Daikin Industries, Ltd., trade name "Daiel G-912", Mooney viscosity: 87.6ML ₁₊₄ , 100°C) which is solid at room temperature and atmospheric pressure as a resin And 10 parts of a phosphoric acid ester (manufactured by Ajinomoto Fine-Techno Co., Inc., trade name “Reophos”) as a flame retardant, using a kneader (manufactured by Inoue Seisakusho) at a temperature of 50° C. for 30 minutes while stirring, By kneading, a composite mixture containing a particulate carbon material, a resin, a fibrous carbon material and a flame retardant was obtained.
[Step of obtaining composite particles]
Next, the composite mixture obtained above is put into a pulverizer (manufactured by Sanjo Industry Co., Ltd., product name "hammer crusher HN34S") and pulverized for 10 seconds to obtain a particulate carbon material, a resin, and a fibrous carbon material. And composite particles for a heat conductive sheet containing a flame retardant were obtained.
Then, for the obtained composite particles for a heat conductive sheet, the volume standard mode diameter of the particulate carbon material in the composite particles for a heat conductive sheet and the SE value of the composite particles for a heat conductive sheet were measured according to the method described above. The results are shown in Table 1.

<Production of heat conduction primary sheet>
[Step of pressing composite particles to form a sheet]
Subsequently, 5 g of the composite particles for a heat conductive sheet obtained as described above were sandwiched by a sandblasted PET film (protective film) having a thickness of 50 μm, a roll gap of 550 μm, a roll temperature of 50° C., a roll linear pressure of 50 kg/cm, The heat conduction primary sheet having a thickness of 0.5 mm was obtained by roll-forming under a roll speed of 1 m/min.
Then, the in-plane thermal conductivity of the obtained heat conductive primary sheet was measured according to the method described above. The results are shown in Table 1.

<Manufacture of heat conduction secondary sheet>
[Step of obtaining laminated body]
In addition, by cutting the heat conductive primary sheet obtained above into a length of 6 cm×width of 6 cm×thickness of 0.5 mm, laminating 120 sheets in the thickness direction, and pressing at 0.1 MPa for 3 minutes at a temperature of 120° C., A laminate having a thickness of about 6 cm was obtained.
[Slicing process]
Then, while pressing the laminated cross section of the laminated body with a pressure of 0.3 MPa, using a slicer for woodworking (manufactured by Marunaka Iron Works, trade name "Super Finishing Planer Super Mechanical S"), with respect to the laminating direction. And sliced at an angle of 0 degree (in other words, sliced in the direction normal to the main surface of the laminated heat-conducting primary sheet) to obtain a heat-conducting secondary sheet having a length of 6 cm×width of 6 cm×thickness of 150 μm. Here, in the knife of a slicer for woodworking, two single blades are in contact with each other on the opposite sides of the cutting blade, and the tip of the front edge is 0.5 mm higher than the tip of the back edge. A two-blade blade having a projection angle of 0.11 mm and a front blade edge angle of 21° was used.

(Example 2)
In the step of obtaining composite particles, after pulverizing the composite mixture, it is classified by using a sieve (manufactured by Tokyo Screen, openings: 500 μm and 850 μm), and heat conduction is performed by using a sieve with an opening of 500 μm and a sieve with an opening of 850 μm. A composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet were produced in the same manner as in Example 1 except that the composite particle for a sheet was obtained.
And it measured like Example 1. The results are shown in Table 1.

(Example 3)
In the step of obtaining composite particles, after pulverizing the composite mixture, it is classified by using a sieve (manufactured by Tokyo Screen, openings: 250 μm and 500 μm), and heat conduction is performed by using a sieve with an opening of 250 μm and a sieve with an opening of 500 μm. A composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet were produced in the same manner as in Example 1 except that the composite particle for a sheet was obtained.
And it measured like Example 1. The results are shown in Table 1.

(Example 4)
In the step of obtaining the composite particles, after pulverizing the composite mixture, it is classified by using a sieve (manufactured by Tokyo Screen, openings: 150 μm and 250 μm), and heat conduction is performed by using a sieve with an opening of 150 μm and a sieve with an opening of 250 μm. A composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet were produced in the same manner as in Example 1 except that the composite particle for a sheet was obtained.
And it measured like Example 1. The results are shown in Table 1.

(Example 5)
In the step of preparing the composite mixture, the resin is a thermoplastic fluororesin that is a solid different from that of Example 1 at room temperature and normal pressure (Kemers, trade name "A-100", Mooney viscosity: 30.2 ML _1+4). , 100° C.), and in the same manner as in Example 1 to produce composite particles for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet.
And it measured like Example 1. The results are shown in Table 1.

(Example 6)
In the step of preparing the composite mixture, the compounding amount of the expanded graphite as the particulate carbon material was changed to 100 parts. Further, the resin was changed to a thermoplastic fluororesin of a type different from that of Example 1 at room temperature and normal pressure (Kermers, trade name “A-100”, Mooney viscosity: 30.2 ML ₁₊₄ , 100° C.). In the same manner as in Example 1 except for the above, a composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet were produced.
And it measured like Example 1. The results are shown in Table 1.

(Example 7)
In the step of preparing the composite mixture, the compounding amount of the expanded graphite as the particulate carbon material was changed to 160 parts. Further, except that the resin is changed to a solid thermoplastic silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KE-931-U”, Mooney viscosity: 15.0 ML ₁₊₄ , 100° C.) under normal temperature and pressure. In the same manner as in Example 1, composite particles for a heat conductive sheet, a heat conductive primary sheet and a heat conductive secondary sheet were produced.
And it measured like Example 1. The results are shown in Table 1.

(Comparative Example 1)
In the step of preparing the composite mixture, the compounding amount of the expanded graphite as the particulate carbon material was changed to 70 parts. Further, the resin was changed to a thermoplastic fluororesin of a type different from that of Example 1 at room temperature and normal pressure (Kermers, trade name “A-100”, Mooney viscosity: 30.2 ML ₁₊₄ , 100° C.). In the same manner as in Example 1 except for the above, a composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet were produced.
And it measured like Example 1. The results are shown in Table 1.

(Comparative example 2)
In the step of preparing the composite mixture, the resin is a solid thermoplastic nitrile rubber at normal temperature and pressure (manufactured by Zeon Corporation, trade name “Nipol (registered trademark) DN3335”, Mooney viscosity: 35.0 ML ₁₊₄ , 100). The same procedure as in Example 1 was carried out except that the temperature was changed to 0° C.) to produce a composite particle for a heat conductive sheet, a heat conductive primary sheet, and a heat conductive secondary sheet.
And it measured like Example 1. The results are shown in Table 1.

(Comparative example 3)
In the step of preparing the composite mixture, the compounding amount of the expanded graphite as the particulate carbon material was changed to 220 parts. Further, the resin is changed to a solid thermoplastic nitrile rubber (manufactured by Nippon Zeon Co., Ltd., trade name “Nipol (registered trademark) DN3335”, Mooney viscosity: 35.0 ML ₁₊₄ , 100° C.) under normal temperature and pressure. In the same manner as in Example 1, a composite particle for a heat conductive sheet, a heat conductive primary sheet and a heat conductive secondary sheet were produced.
And it measured like Example 1. The results are shown in Table 1.

From Table 1, in Examples 1 to 7 using the composite particles for a heat conductive sheet, which include the particulate carbon material and the resin and have an SE value of 6.0 mJ/g or more and 16.0 mJ/g or less, It can be seen that the heat conductivity in the in-plane direction of the heat conductive primary sheet is excellent as compared with Comparative Examples 1 to 3 in which the SE value of the composite particles for a sheet is outside the above range.
Moreover, in Examples 2 to 4 in which the composite particles for a heat conductive sheet were prepared by classification, the SE value increases as the particle diameter of the particle group of the composite particles decreases, and the heat in the in-plane direction of the heat conductive primary sheet increases. There was a tendency for the conductivity to increase.
Further, in Examples 5 to 6 in which a solid thermoplastic fluororesin having a lower Mooney viscosity under normal temperature and normal pressure is used, Example 1 in which a solid thermoplastic fluororesin having a higher Mooney viscosity under normal temperature and normal pressure is used. It was observed that the SE value tended to be larger than that of -4.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the heat conductive sheet which can manufacture the heat conductive primary sheet excellent in the heat conductivity in the in-plane direction and the heat conductive secondary sheet excellent in the heat conductivity in the thickness direction can be provided. it can.
Further, according to the present invention, a composite particle for a heat conductive sheet that can be used for producing a heat conductive primary sheet having excellent heat conductivity in the in-plane direction and a heat conductive secondary sheet having excellent heat conductivity in the thickness direction. It is also possible to provide a method for producing composite particles for a heat conductive sheet, which is capable of preparing the composite particles.
Further, according to the present invention, it is possible to provide a method of manufacturing a heat-conducting primary sheet-equipped heating element and a laminated sheet-equipped heating element having excellent heat dissipation characteristics.

Claims (9)

Including particulate carbon material and resin,
Composite particles for a heat conductive sheet having an SE value of 6.0 mJ/g or more and 16.0 mJ/g or less. The composite particle for a heat conductive sheet according to claim 1, wherein the content ratio of the particulate carbon material is 40% by volume or more. The composite particle for a heat conductive sheet according to claim 1, wherein the particulate carbon material is expanded graphite. The composite particles for a heat conductive sheet according to claim 1, wherein the resin is a thermoplastic resin. Providing a composite mixture containing a particulate carbon material and a resin,
Pulverizing the composite mixture to obtain composite particles having an SE value of 6.0 mJ/g or more and 16.0 mJ/g or less,
A method for producing composite particles for a heat conductive sheet, comprising: A step of pressurizing the composite particles for a heat conductive sheet according to any one of claims 1 to 4 or the composite particles for a heat conductive sheet obtained by the manufacturing method according to claim 5 to form a sheet. A method of manufacturing a heat conductive primary sheet, comprising: A plurality of heat-conducting primary sheets obtained by the manufacturing method according to claim 6 are laminated in the thickness direction, or the heat-conducting primary sheet obtained by the manufacturing method according to claim 6 is folded or wound. To obtain a laminated body,
A slicing step of slicing the laminated body at an angle of 45° or less with respect to the laminating direction to obtain a heat conductive secondary sheet;
A method for producing a heat conductive secondary sheet, comprising: A method for producing a heating element with a heat conduction primary sheet, comprising the step of adhering the heat conduction primary sheet obtained by the production method according to claim 6 to at least one surface of the heating element. A step of bonding a laminated sheet having the heat-conducting primary sheet obtained by the manufacturing method according to claim 6 and the heat-conducting secondary sheet obtained by the manufacturing method according to claim 7 to at least one surface of the heating element. A method for producing a heating element with a laminated sheet, comprising: