JP2021086887A - Thermal conductivity sheet and manufacturing method thereof - Google Patents

Abstract

To provide a thermal conductivity sheet that exhibits high thermal conductivity and can also exhibit other functions such as conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, or air permeability.SOLUTION: A thermal conductivity sheet includes a plurality of thermal conductors including a polymer matrix and a thermal conductivity filler, a polymer matrix, and a combination with any of a conductive filler, an electromagnetically absorbent filler, a flame retardant filler, an adsorptive filler, and continuous pores, or a plurality of functional units including metals, and the thermal conductor and the functional unit are flush with each other on the front surface and the back surface of the thermal conductivity sheet.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermally conductive sheet and a method for producing the same.

In electronic devices such as computers, automobile parts, and mobile phones, a heat sink such as a heat sink is generally used to dissipate heat generated from a heating element such as a semiconductor element or a mechanical part. It is known that a heat conductive sheet is arranged between a heating element and a heat radiating element for the purpose of increasing the heat transfer efficiency to the heat radiating element.
The heat conductive sheet generally contains a polymer matrix and a heat conductive filler dispersed in the polymer matrix. Further, in the heat conductive sheet, in order to enhance the heat conductivity in a specific direction, an anisotropic filler having anisotropy in shape may be oriented in one direction.

For the thermally conductive sheet in which the anisotropic filler is oriented in one direction, for example, a plurality of primary sheets in which the anisotropic filler is oriented along the sheet surface direction are produced by stretching or the like, and the primary sheet is produced. It is manufactured by vertically slicing a product obtained by stacking and integrating a plurality of the above. According to this manufacturing method (hereinafter, also referred to as “fluid orientation method”), a thermally conductive sheet formed by laminating a large number of unit layers having a small thickness can be obtained. Further, the anisotropic filler can be oriented in the thickness direction of the sheet (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-27144

According to Patent Document 1, a certain degree of good thermal conductivity can be obtained. However, with the recent increase in functionality of electronic devices such as computers, automobile parts, and mobile phones, even in the case of thermally conductive sheets, in addition to good thermal conductivity, conductivity, electromagnetic wave absorption, flame retardancy, and adsorptivity Or, it is preferable that other functions such as breathability can be exhibited. With such a heat conductive sheet, the characteristics of the electronic device can be more effectively exhibited according to the use and shape of the electronic device.

Therefore, the present invention provides a heat conductive sheet that exhibits high thermal conductivity and can also exhibit other functions such as conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, or air permeability. Is the subject.

As a result of diligent studies, the present inventor has found that the above problems can be solved by having the following configuration, and has completed the present invention. That is, the present invention provides the following [1] to [13].
[1] A plurality of heat conductive parts including a polymer matrix and a heat conductive filler, and
A combination of a polymer matrix with any of a conductive filler, an electromagnetically absorbing filler, a flame-retardant filler, an adsorptive filler, and continuous pores, or a thermal conductivity having a plurality of functional parts containing a metal. A heat conductive sheet, wherein the heat conductive portion and the functional portion are flush with each other on the front surface and the back surface of the heat conductive sheet.
[2] The heat conductive sheet according to [1], wherein the heat conductive portion and the functional portion are alternately laminated in the plane direction.
[3] The heat conductive portion is a heat conductive layer extending linearly in a predetermined direction on each of the front surface and the back surface of the heat conductive sheet, and the functional part is a functional layer extending in parallel with the heat conductive layer. Or, the heat conductive sheet according to [1] or [2], which is a dot-shaped functional portion intermittently arranged in parallel with the heat conductive layer.
[4] The heat conductive sheet according to any one of [1] to [3], wherein the heat conductive filler contains an anisotropic filler.
[5] The heat conductive sheet according to any one of [1] to [4], wherein the heat conductive filler contains a non-anisotropic filler.
[6] The heat conductive sheet according to [4] or [5], wherein the anisotropic filler is oriented in the thickness direction of the sheet.
[7] The heat conductive sheet according to any one of [4] to [6], wherein the anisotropic filler is at least one selected from a fibrous material and a scaly material.
[8] The heat conductive sheet according to [7], wherein the normal direction of the scale surface of the scaly material is oriented in the stacking direction of the plurality of heat conductive layers.
[9] The heat conductive sheet according to any one of [1] to [8], wherein the adjacent heat conductive portion and the functional portion are directly fixed to each other.
[10] A step of preparing a plurality of thermally conductive primary sheets, each containing a polymer matrix and a thermally conductive filler, and a polymer matrix, a conductive filler, an electromagnetic wave absorbing filler, and difficulty, respectively. A combination with any of a flammable filler, an adsorptive filler, and continuous pores, or a step of preparing a plurality of functional members containing a metal, and laminating the plurality of primary sheets and the plurality of functional members. A method for producing a thermally conductive sheet, comprising a step of adhering to form a laminated block and a step of cutting the laminated block into a sheet shape along the lamination direction to obtain a thermally conductive sheet. ..
[11] In a step of forming a laminated block, a step of irradiating at least one surface of the heat conductive primary sheet with vacuum ultraviolet rays after preparing a plurality of the heat conductive primary sheets is provided. The heat conduction according to [10], wherein the heat conductive primary sheet is laminated so that one surface irradiated with vacuum ultraviolet rays is brought into contact with the functional member to form a laminated block. Method of manufacturing sex sheet.
[12] The thermally conductive filler contains an anisotropic filler, and in the thermally conductive primary sheet, the anisotropic filler is oriented along the plane direction thereof, and the laminated block is different from the above. The method for producing a thermally conductive sheet according to [10] or [11], wherein the anisotropic filler is cut in a direction orthogonal to the orientation direction.
[13] The method for producing a thermally conductive sheet according to any one of [10] to [12], wherein the thermally conductive filler contains a non-anisotropic filler.

According to the present invention, there is provided a heat conductive sheet that exhibits high thermal conductivity and can also exhibit other functions such as conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, or air permeability. Can be done.

It is a schematic perspective view which shows an example of the heat conductive sheet of this embodiment. It is a schematic perspective view which shows another example of the heat conductive sheet of this embodiment. It is a schematic cross-sectional view which shows the heat conductive sheet of 1st Embodiment. It is a schematic cross-sectional view which shows the heat conductive sheet of 2nd Embodiment. It is a schematic cross-sectional view which shows the heat conductive sheet of 3rd Embodiment. It is a schematic perspective view which shows an example of the manufacturing method of the heat conductive sheet of this embodiment. It is a schematic perspective view which shows another example of the manufacturing method of the heat conductive sheet of this embodiment.

Hereinafter, the heat conductive sheet according to the embodiment of the present invention will be described in detail.
The heat conductive sheet according to the present embodiment includes a plurality of heat conductive parts including a polymer matrix and a heat conductive filler, a polymer matrix, a conductive filler, an electromagnetic wave absorbing filler, and a flame-retardant filler. , A combination of an adsorptive filler and any of the continuous pores, or a plurality of functional parts containing a metal. The heat conductive portion and the functional portion are flush with each other on the front surface and the back surface of the heat conductive sheet.
By coexisting the heat conductive part and the functional part in the heat conductive sheet, each function can be effectively exhibited. In particular, since the heat conductive part and the functional part are flush with each other on the front surface and the back surface of the heat conductive sheet, the heat conductive part and the functional part are exposed on each surface. These can be reliably brought into contact with the member on which the sheet is arranged. As a result, thermal conductivity is exhibited from the heat conductive part, and conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, and air permeability due to continuous pores are efficiently exhibited from the functional part depending on the type of filler. To.

Here, "the heat conductive part and the functional part are flush with each other" means that the functional part includes a conductive filler, an electromagnetic wave absorbing filler, a flame-retardant filler, or an adsorptive filler. , The resin surface of the matrix that composes each is connected flatly without steps, and as long as it is, a part of the filler is not protruding or unevenness that does not impair the adhesion to the installation target. May have.
When the functional portion includes continuous pores, it means that the resin surface of the polymer matrix constituting the functional portion is equal to or lower than the height of the resin surface of the polymer matrix constituting the heat conductive portion sandwiching the functional portion.

The method of arranging the plurality of heat conductive parts and the plurality of functional parts is not particularly limited and may be randomly arranged, but in consideration of the productivity of the sheet, the heat conductive parts are alternately arranged in the plane direction or two layers are laminated. Is preferable.

Specifically, from the viewpoint that if a plurality of sheets having different properties are prepared, it is easy to meet different demands by changing the combination thereof, as shown in FIG. 1, the heat conductive portion 13A is used. A heat conductive layer extending linearly (preferably linearly) in a predetermined direction on each of the front surface and the back surface of the heat conductive sheet 10, and the functional portion 13B is a functional layer 13B extending in parallel with the heat conductive layer. Is preferable.

The ratio of the width WB of the functional layer adjacent to the heat conductive layer to the width WA of 1 heat conductive layer from the viewpoint of sufficiently exerting the functionality exhibited from the functional portion while exhibiting good thermal conductivity ( WB / WA) is preferably 0.001 to 0.5. When the conductive portion is a metal layer, it is more preferably 0.001 to 0.1. On the other hand, when the conductive portion is a combination of the polymer matrix and the conductive filler, it is more preferably 0.02 to 0.5.
From the same viewpoint, in the functional layer other than the functional layer containing continuous pores, the area of the functional layer adjacent to the heat conductive layer with respect to the area SA of 1 heat conductive layer in an arbitrary cross section intersecting the laminated surface. The ratio of SB (SB / SA) is preferably 0.001 to 0.5. Further, when the conductive portion is a metal layer, it is more preferably 0.001 to 0.1, and when the conductive portion is a combination of a polymer matrix and a conductive filler, 0.02 to 0 It is more preferably .5.
Furthermore, from the same viewpoint, in the functional layer other than the functional layer containing continuous pores, the ratio of the volume VB of the functional layer adjacent to the heat conductive layer to the volume VA of one heat conductive layer (VB / VA). Is preferably 0.001 to 0.5. Further, when the conductive portion is a metal layer, it is more preferably 0.001 to 0.1, and when the conductive portion is a combination of a polymer matrix and a conductive filler, 0.02 to 0 It is more preferably .5.
The case of the functional layer containing continuous pores will be described later.
Further, it is preferable that the heat conductive layer and the functional layer are formed from the front surface to the back surface of the heat conductive sheet, respectively.

Further, as shown in FIG. 2, from the viewpoint of sufficiently exerting the functionality to be effectively exerted from the functional part even with a small amount of the functional part when an expensive member is used as the functional part, heat conduction The part 13A is a heat conductive layer extending linearly in a predetermined direction on each of the front surface and the back surface of the heat conductive sheet 10, and the functional part is a dot-shaped functional part intermittently arranged in parallel with the heat conductive layer. Is preferable.
In this case as well, from the viewpoint of sufficiently exerting the functionality exhibited by the functional portion while exhibiting good thermal conductivity, the dot-shaped functional portion with respect to the projected area SA of the thermal conductive layer on one surface of the thermal conductive sheet 10. The ratio (SB / SA) of the projected area SB is preferably 0.00001 to 0.25, and more preferably 0.0004 to 0.25.
The shape of the dot-shaped functional portion exposed on the front surface and the back surface is not particularly limited, such as a circular shape, an elliptical shape, a polygonal shape, or a combined shape thereof. Further, the dot-shaped functional portion is formed from the front surface to the back surface.

In the present embodiment, the first embodiment in which the thermally conductive filler contains the anisotropic filler and the non-isomeric filler, the thermally conductive filler contains the anisotropic filler and is non-different. Preferred embodiments include a second embodiment that does not contain a square filler and a third embodiment in which the thermally conductive filler contains a non-isometric filler and does not contain an anisotropic filler. Can be mentioned.

[First Embodiment]
FIG. 3 shows an example of the heat conductive sheet 100 of the first embodiment. The heat conductive sheet 100 according to the first embodiment includes a plurality of heat conductive portions 13A each containing a polymer matrix 11 and a heat conductive filler, a conductive filler, an electromagnetic wave absorbing filler, and the like. A functional layer 13B containing a filler 16 such as a flame-retardant filler or an adsorptive filler is provided. These layers are laminated along one direction along the plane direction (that is, one direction perpendicular to the thickness direction z, also referred to as "stacking direction x"), and adjacent layers are preferably laminated. The heat conductive layer 13A, which is the heat conductive portion 13A, and the functional layer 13B, which is the functional portion 13B, are alternately laminated and adhered in the plane direction.

The thermally conductive sheet 100 contains an anisotropic filler 14 and a non-anisotropic filler 15 as the thermally conductive filler. The anisotropic filler 14 is oriented in the thickness direction z of the sheet 10. That is, each heat conductive layer 13A is oriented along one direction in the plane direction. By containing the anisotropic filler 14 oriented in the thickness direction z of the sheet, the heat conductive sheet 100 improves the heat conductivity of the heat conductive layer 13A in the thickness direction z. The thermal conductivity of the heat conductive layer 13A is further improved by further containing the non-anisotropic filler 15.
Further, various functions are exhibited by the filler 16 of the functional portion 13B.

Hereinafter, the heat conductive portion including the polymer matrix and the heat conductive filler, and the polymer matrix, the conductive filler, the electromagnetic wave absorbing filler, the flame-retardant filler, the adsorptive filler, and the continuous pores. The combination with any of them, the functional part containing metal, and the like will be described.

<Heat conduction part>
(Polymer matrix)
The polymer matrix 11 is a member that holds the filler, and is preferably made of a flexible rubber-like elastic body. The polymer matrix is formed from a resin that is a precursor thereof. The precursor referred to in the present specification is a concept that includes not only a substance that becomes a polymer matrix by reacting as described later, but also a substance that does not react and is the same as the polymer matrix.
In order for the anisotropic filler to be contained in the polymer matrix 11 in a state of being oriented in the heat conductive portion, it is required that the resin has fluidity during the alignment step. For example, if the resin that is the precursor of the polymer matrix is a thermoplastic resin, the anisotropic filler can be oriented in a state of being heated and plasticized. Further, in the case of a reactive liquid resin, if the anisotropic filler is oriented before curing and the resin is cured while maintaining the state, a cured product in which the anisotropic filler is oriented can be obtained. The former has a relatively high viscosity, and if it is plasticized to a low viscosity, the resin may be thermally deteriorated. Therefore, it is preferable to use the latter resin.

As the reactive liquid resin, it is preferable to use a rubber or gel which is liquid before the reaction and is cured under predetermined conditions to form a crosslinked structure. The crosslinked structure means that at least a part of the polymer is three-dimensionally crosslinked to form a cured product which is not melted by heating. Further, since a mixed composition in which an anisotropic filler is added to a liquid resin is prepared and these are oriented in a fluid liquid resin, the viscosity is preferably low, and after orientation, the mixture is cured under predetermined conditions. Those having possible properties are preferable.

Examples of the curing method of such a reactive liquid resin include thermosetting and photocurable ones, but since they may contain a large amount of a filler such as a scaly filler that blocks light, they are thermosetting. It is preferable to use the rubber or gel of. More specifically, silicone resin, urethane rubber utilizing the reaction of polyol and isocyanate, acrylic rubber utilizing the radical reaction or cationic reaction of acrylate, and the like can be exemplified, but it is preferable to use a silicone resin.

The silicone resin is not particularly limited as long as it is an organopolysiloxane, but it is preferable to use a curable silicone resin. In the case of a curable type, the silicone resin is obtained by curing the curable silicone composition. As the silicone resin, an addition reaction type silicone resin may be used, or other silicone resins may be used. In the case of the addition reaction type, the curable silicone composition preferably comprises a silicone compound as a main agent and a curing agent that cures the main agent.

The silicone compound used as the main agent is preferably an alkenyl group-containing organopolysiloxane, and specifically, a vinyl group-containing polydimethylsiloxane, a vinyl group-containing polyphenylmethylsiloxane, a vinyl group-containing dimethylsiloxane-diphenylsiloxane copolymer, and a vinyl group. Examples thereof include vinyl group-containing organopolysiloxanes such as a vinyl group-containing dimethylsiloxane-phenylmethylsiloxane copolymer and a vinyl group-containing dimethylsiloxane-diethylsiloxane copolymer.

The curing agent is not particularly limited as long as it can cure the silicone compound as the main agent, but organohydrogenpolysiloxane, which is an organopolysiloxane having two or more hydrosilyl groups (SiH), is preferable.
The hardness of the primary sheet, which will be described later, can be adjusted by appropriately adjusting the number of hydrosilyl groups, the molecular weight, and the compounding amount ratio with respect to the main agent of the curing agent. Specifically, the hardness of the primary sheet can be lowered by using a curing agent having a small number of hydrosilyl groups in one molecule or having a large molecular weight, or by reducing the mixing amount ratio of the curing agent to the main agent.

The content of the polymer matrix in the heat conductive portion is preferably 15 to 50% by volume, more preferably 20 to 45% by volume, based on the heat conductive portion of the heat conductive sheet in terms of volume% (filling ratio). Is.
The content of the polymer matrix in the functional part is preferably 10 to 99.5% by volume with respect to the functional part of the heat conductive sheet. In addition, the content of the polymer matrix is 20 to 75% by volume when the functional part is capable of exerting the conductivity and the polymer matrix is composed of a layer other than the metal layer, and the electromagnetic wave absorption is exhibited. It is more preferably 10 to 50% by volume when it is allowed to be used, 15 to 60% by volume when the flame retardancy is developed, and 70 to 99.5% by volume when the adsorptivity is developed. In addition, in the case of exhibiting breathability, a predetermined additive may be contained, but all except pores may be composed of a polymer matrix.

(Anisotropic filler)
The anisotropic filler 14 is a filler having anisotropy in shape and capable of orientation. Examples of the anisotropic filler 14 include fibrous materials and scaly materials, and at least one selected from these is preferable. The anisotropic filler 14 generally has a high aspect ratio, has an aspect ratio of more than 2, and is more preferably 5 or more. By making the aspect ratio larger than 2, the anisotropic filler 14 can be easily oriented in the thickness direction z, and the thermal conductivity of the heat conductive sheet 100 can be easily increased.

The upper limit of the aspect ratio is not particularly limited, but is practically 300.
The aspect ratio is the ratio of the length in the major axis direction to the length in the minor axis direction of the anisotropic filler 14, which means the fiber length / fiber diameter in the fibrous material, and is scaly. In terms of material, it means the length / thickness of the scaly material in the major axis direction.

The content of the anisotropic filler 14 in the heat conductive portion 13A of the heat conductive sheet 100 is preferably 10 to 500 parts by mass and 50 to 350 parts by mass with respect to 100 parts by mass of the polymer matrix. Is more preferable. The content of the anisotropic filler 14 is preferably 2 to 50% by volume, more preferably 8 to 40 volumes, based on the volume-based filling rate (volume filling rate) with respect to the total amount of the heat conductive portion. %.
When the content of the anisotropic filler 14 is 10 parts by mass or more, the thermal conductivity is easily increased, and when the content is 500 parts by mass or less, the viscosity of the liquid composition described later is likely to be appropriate, which is different. The orientation of the anisotropic filler 14 is improved.

When the anisotropic filler 14 is a fibrous material, its average fiber length is preferably 20 to 500 μm, more preferably 80 to 400 μm. When the average fiber length is 10 μm or more, the anisotropic fillers are appropriately contacted with each other in each heat conductive sheet 100, a heat transfer path is secured, and the heat conductivity of the heat conductive sheet 100 is improved. ..
On the other hand, when the average fiber length is 500 μm or less, the bulk of the anisotropic filler becomes low, and the polymer matrix (particularly silicone resin) can be highly filled. Further, even if an anisotropic filler 14 having conductivity is used, it is possible to prevent the thermal conductivity sheet 100 from becoming unnecessarily high in conductivity.
The average fiber length can be calculated by observing the anisotropic filler with a microscope. More specifically, for example, with respect to the anisotropic filler 14 separated by melting the matrix component of the heat conductive sheet 100, the fiber lengths of 50 arbitrary anisotropic fillers are used by using an electron microscope or an optical microscope. Can be measured and the average value (arithmetic mean value) can be used as the average fiber length. At this time, do not take a large share so as not to crush the fiber. When it is difficult to separate the anisotropic filler 14 from the heat conductive sheet 100, the fiber length of the anisotropic filler 40 is measured using an X-ray CT apparatus to calculate the average fiber length. You may.
Further, the diameter of the anisotropic filler 14 can also be measured by using an electron microscope, an optical microscope, and an X-ray CT apparatus in the same manner.
In the present invention, the arbitrary one means a randomly selected one.

When the anisotropic filler 14 is a scaly material, the average particle size thereof is preferably 20 to 400 μm, more preferably 30 to 300 μm. Further, 40 to 200 μm is particularly preferable. By setting the average particle size to 10 μm or more, the anisotropic fillers 14 easily come into contact with each other in the heat conductive sheet 100, a heat transfer path is secured, and the heat conductivity of the heat conductive sheet 100 is good. Become. On the other hand, when the average particle size is 400 μm or less, the bulk of the anisotropic filler 14 becomes low, and the anisotropic filler 14 in the polymer matrix 11 can be highly filled.
The average particle size of the scaly material can be calculated by observing the anisotropic filler with a microscope and using the major axis as the diameter. More specifically, the major axis of 50 arbitrary anisotropic fillers is measured using an electron microscope, an optical microscope, and an X-ray CT device in the same manner as the average fiber length, and the average value (arithmetic mean) is measured. Value) can be the average particle size.
Further, the thickness of the anisotropic filler 14 can also be similarly measured using an electron microscope, an optical microscope, and an X-ray CT apparatus.

Specific examples of the anisotropic filler 14 include carbon fibers, carbon-based materials typified by scaly carbon powder, metal materials and metal oxides typified by metal fibers, boron nitride, metal nitrides, and metals. Carbides, metal hydroxides, polyparaphenylene benzoxazole fibers and the like can be mentioned. Among these, the carbon-based material is preferable because it has a small specific gravity and good dispersibility in the polymer matrix 11, and among these, a graphitized carbon material having a high thermal conductivity is more preferable. Further, boron nitride and polyparaphenylene benzoxazole fibers are preferable from the viewpoint of having insulating properties, and boron nitride is more preferable. Boron nitride is not particularly limited, but is preferably used as a scaly material. The scaly boron nitride may or may not be agglomerated, but it is preferable that part or all of the scaly boron nitride is not agglomerated.

The anisotropic filler 14 is not particularly limited, but has a thermal conductivity generally 30 W / m · K or more, preferably 100 W / m, along the direction having anisotropy (that is, the major axis direction).・ K or higher. The upper limit of the thermal conductivity of the anisotropic filler 14 is not particularly limited, but is, for example, 2000 W / m · K or less. The method for measuring thermal conductivity is a laser flash method.

The anisotropic filler 14 may be used alone or in combination of two or more. For example, as the anisotropic filler 14, at least two anisotropic fillers 14 having different average particle diameters or average fiber lengths may be used. When anisotropic fillers of different sizes are used, small anisotropic fillers are inserted between relatively large anisotropic fillers, so that the anisotropic filler is a polymer matrix (particularly silicone resin). It is considered that the inside can be filled with high density and the heat conduction efficiency can be improved.

The carbon fiber used as the anisotropic filler 14 is preferably graphitized carbon fiber. Further, as the scaly carbon powder, scaly graphite powder is preferable. Of these, the anisotropic filler 14 is more preferably graphitized carbon fiber.
The graphitized carbon fibers have graphite crystal planes connected in the fiber axis direction, and have high thermal conductivity in the fiber axis direction. Therefore, by aligning the fiber axis directions in a predetermined direction, the thermal conductivity in a specific direction can be increased. Further, the scaly graphite powder has graphite crystal planes connected in the in-plane direction of the scaly plane, and has high thermal conductivity in the in-plane direction. Therefore, by aligning the scale surfaces in a predetermined direction, the thermal conductivity in a specific direction can be increased. The graphitized carbon fiber and the scaly graphite powder are preferably those having a high degree of graphitization.

As the graphitized carbon material such as the graphitized carbon fiber described above, a graphitized material of the following raw materials can be used. Examples thereof include condensed polycyclic hydrocarbon compounds such as naphthalene, condensed heterocyclic compounds such as PAN (polyacrylonitrile) and pitch, and graphitized mesophase pitch, polyimide and polybenzazole having a particularly high degree of graphitization should be used. Is preferable. For example, by using the mesophase pitch, in the spinning process described later, the pitch is oriented in the fiber axis direction due to its anisotropy, and graphitized carbon fibers having excellent thermal conductivity in the fiber axis direction can be obtained.
The mode of use of the mesophase pitch in the graphitized carbon fiber is not particularly limited as long as it can be spun, and the mesophase pitch may be used alone or in combination with other raw materials. However, the use of the mesophase pitch alone, that is, the graphitized carbon fiber having a mesophase pitch content of 100% is most preferable from the viewpoint of high thermal conductivity, spinnability and quality stability.

As the graphitized carbon fiber, one that has been subjected to each treatment of spinning, insolubilization and carbonization in sequence and pulverized or cut to a predetermined particle size and then graphitized, or one that has been pulverized or cut after carbonization and then graphitized may be used. it can. When crushing or cutting before graphitization, the polycondensation reaction and cyclization reaction easily proceed during the graphitization treatment on the surface newly exposed by pulverization, so that the degree of graphitization is increased and heat conduction is further increased. Graphitized carbon fibers with improved properties can be obtained. On the other hand, when the spun carbon fibers are graphitized and then pulverized, the carbon fibers after graphitization are rigid and easily pulverized, and carbon fiber powder having a relatively narrow fiber length distribution can be obtained by pulverization in a short time.

The average fiber length of the graphitized carbon fibers is preferably 50 to 500 μm, more preferably 70 to 350 μm. Further, the aspect ratio of the graphitized carbon fiber exceeds 2 as described above, and is preferably 5 or more. The thermal conductivity of the graphitized carbon fiber is not particularly limited, but the thermal conductivity in the fiber axis direction is preferably 400 W / m · K or more, and more preferably 800 W / m · K or more.

The anisotropic filler 14 is oriented in the thickness direction z of the heat conductive sheet in each heat conductive portion 13A. More specifically, the orientation of the anisotropic filler 14 in the thickness direction z will be described more specifically when the thermally conductive filler 14 is a fibrous filler, with respect to the thickness direction z of the thermally conductive sheet 100. It means that the ratio of the number of anisotropic fillers in which the angle formed by the long axis of the fibrous filler is less than 30 ° exceeds 50% with respect to the total amount of the anisotropic filler. , Preferably greater than 80%.
When the anisotropic filler 14 is a scaly filler, the angle formed by the scaly surface of the scaly filler with respect to the thickness direction z of the heat conductive sheet 100 is less than 30 ° anisotropic. It means that the ratio of the number of fillers exceeds 50% with respect to the total amount of the anisotropic filler, and the ratio can preferably exceed 80%. In other words, the ratio of the number of anisotropic fillers having an angle formed by the normal direction of the scaly surface of less than 30 ° with respect to the sheet surface (xy surface) of the thermally conductive sheet is anisotropic filling. It means that it is in a state of exceeding 50% with respect to the total amount of the material, and the ratio preferably exceeds 80%.
The orientation direction of the anisotropic filler 14 is preferably 0 ° or more and less than 5 ° from the viewpoint of increasing the thermal conductivity, that is, the angle formed by the long axis or the angle formed by the scaly surface with respect to the thickness direction z. On the other hand, the heat conductive sheet 100 can be tilted in a range of 5 ° or more and less than 30 ° in that the load when compressed can be reduced. These angles are average values of the orientation angles of a fixed number of anisotropic fillers 14 (for example, 50 arbitrary anisotropic fillers 14).
Further, the anisotropic filler 14 has a major axis of the anisotropic filler 14 with respect to the thickness direction z of the thermally conductive sheet 100 when the thermally conductive filler 14 is neither fibrous nor scaly. It means that the ratio of the number of anisotropic fillers having an angle of less than 30 ° is more than 50% with respect to the total amount of the anisotropic filler, and the ratio is preferably more than 80%. Shall be.

Further, when the anisotropic filler 14 is a scaly material, it is preferable that the normal direction of the scaly surface of the anisotropic filler 14 faces a predetermined direction, and specifically, a plurality of heat conductions are carried out. It is preferable that the layer 13A faces the stacking direction x. By directing the normal direction to the stacking direction x in this way, the thermal conductivity of the heat conductive sheet 100 in the thickness direction z is improved. Further, the thermal conductivity in the direction along the plane direction of the thermal conductive sheet 100 and in the direction orthogonal to the stacking direction x is also improved.
The fact that the normal direction of the scale surface faces the stacking direction x means that the ratio of the number of carbon fiber powders having an angle formed by the normal direction to the stacking direction x of less than 30 ° exceeds 50%. The ratio preferably exceeds 80%.
When the anisotropic filler 14 is a scaly material, the normal direction of the scaly surface is laminated by forming the anisotropic filler 14 into a sheet while applying a shearing force as described in the manufacturing method described later. It will face the direction x.

Further, the anisotropic filler may have conductivity or insulation. When the scaly filler and the fibrous filler have an insulating property, the insulating property in the thickness direction of the heat conductive sheet can be enhanced, so that the scaly filler and the fibrous filler can be suitably used in electrical equipment. Note that the heat-conducting portion has a conductivity in the present invention, for example, a volume resistivity shall refer to the following cases 1 × 10 ⁹ Ω · cm. Further, as having insulating property shall refer to for example, when the volume resistivity is more than 1 × 10 ⁹ Ω · cm.

(Non-anisotropic filler)
The non-anisotropic filler 15 is a thermally conductive filler contained in the heat conductive portion 13A of the heat conductive sheet 100 separately from the anisotropic filler 14, and is thermally conductive together with the anisotropic filler 14. It is a material that imparts thermal conductivity to the sheet 100. In the present embodiment, since the non-anisotropic filler 15 is contained, the filler is interposed in the gap between the oriented anisotropic fillers 14, and the thermally conductive sheet 100 having high thermal conductivity is obtained. Be done.
The non-anisotropic filler 15 is a filler having substantially no anisotropy in shape, and even in an environment in which the anisotropic filler 14 is oriented in a predetermined direction, such as under the action of shearing force described later. , A filler that does not orient in its predetermined direction.

The non-anisotropic filler 15 has an aspect ratio of 2 or less, more preferably 1.5 or less. In the present embodiment, since the non-anisotropic filler 15 having such a low aspect ratio is contained, the filler having thermal conductivity is appropriately interposed in the gaps of the anisotropic filler 14, and the heat conduction is achieved. A heat conductive sheet 100 having a high rate can be obtained. Further, by setting the aspect ratio to 2 or less, it is possible to prevent the viscosity of the liquid composition described later from increasing and to achieve high filling.

The non-anisotropic filler 15 may have conductivity, but preferably has an insulating property, and in the heat conductive portion (heat conductive layer 13A), the anisotropic filler 14 and the non-anisotropic filler 14 and the non-anisotropic filler 14 are used. It is preferable that both fillers 15 have insulating properties. As described above, when both the anisotropic filler 14 and the non-anisotropic filler 15 are insulating, it becomes easier to further enhance the insulating property of the heat conductive portion (heat conductive layer 13A) in the thickness direction z. ..

Specific examples of the non-anisometric filler 15 include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, oxides other than metals, nitrides, carbides and the like. The shape of the non-anisotropic filler 14 includes spherical and amorphous powders.
In the non-anisometric filler 15, the metal is aluminum, copper, nickel, etc., the metal oxide is aluminum oxide, magnesium oxide, zinc oxide, etc. represented by alumina, and the metal nitride is aluminum nitride, etc. It can be exemplified. Examples of the metal hydroxide include aluminum hydroxide. Further, examples of the carbon material include spheroidal graphite. Examples of oxides, nitrides and carbides other than metals include quartz, boron nitride and silicon carbide.
Among these, aluminum oxide and aluminum are preferable because they have high thermal conductivity and spherical ones are easily available, and aluminum hydroxide is preferable because they are easily available and the flame retardancy of the heat conductive sheet can be enhanced. ..
Among the above, examples of the non-isometric filler 15 having an insulating property include metal oxides, metal nitrides, metal hydroxides, and metal carbides, and aluminum oxide and aluminum hydroxide are particularly preferable.
As the non-anisotropic filler 15, one of the above-mentioned ones may be used alone, or two or more of them may be used in combination.

The average particle size of the non-anisotropic filler 15 is preferably 0.1 to 50 μm, more preferably 0.5 to 35 μm. Further, it is particularly preferably 1 to 15 μm. By setting the average particle size to 50 μm or less, problems such as disturbing the orientation of the anisotropic filler 14 are less likely to occur. Further, by setting the average particle size to 0.1 μm or more, the specific surface area of the non-anisotropic filler 15 does not become larger than necessary, and the viscosity of the liquid composition does not easily increase even if a large amount is blended. It becomes easy to highly fill the anisotropic filler 15.
The average particle size of the non-anisotropic filler 15 can be measured by observing with an electron microscope or the like. More specifically, the particle size of 50 arbitrary non-anometric fillers is measured by using an electron microscope, an optical microscope, and an X-ray CT device in the same manner as the measurement with the anisotropic filler. The average value (arithmetic mean value) can be used as the average particle size.

The content of the non-anisotropic filler 15 in the heat conductive portion 13A of the heat conductive sheet 100 is preferably in the range of 50 to 1500 parts by mass and 200 to 800 parts by mass with respect to 100 parts by mass of the polymer matrix. More preferably, it is in the range of parts. When the amount is 50 parts by mass or more, the amount of the non-anisotropic filler 15 interposed in the gap between the anisotropic fillers 14 becomes a certain amount or more, and the thermal conductivity is improved. On the other hand, when the content is 1500 parts by mass or less, the effect of increasing the heat conductivity according to the content can be obtained, and the non-anisotropic filler 15 inhibits the heat conduction by the anisotropic filler 14. There is no such thing. Further, when the content is in the range of 200 to 800 parts by mass, the thermal conductivity of the heat conductive sheet 100 is excellent, and the viscosity of the liquid composition for forming the heat conductive portion is also suitable.
The content of the non-anisotropic filler 15 is preferably 10 to 75% by volume, more preferably 30 to 60% by volume, based on the total amount of the heat conductive portion.

<Functional part>
The functional unit 13B is composed of a combination of a polymer matrix and any of a conductive filler, an electromagnetic wave absorbing filler, a flame-retardant filler, an adsorptive filler, and continuous pores, and one containing a metal. Can be mentioned. When the functional part 13B is made of the above combination, the functional part including the conductive filler becomes a conductive part, the functional part including the electromagnetic wave absorbing filler becomes an electromagnetic wave absorbing part, and the functional part including the flame-retardant filler is difficult. It becomes a flammable part, the functional part including the adsorptive filler becomes a suction part, and the functional part including continuous pores becomes a ventilation part.
When the functional part 13B is made of a metal-containing material, for example, if the metal layer has conductivity, it becomes a conductive part, and if it has electromagnetic absorption, it becomes an electromagnetic wave absorbing part and has flame retardancy. If it is, it becomes a flame-retardant part, if it has adsorptivity, it becomes a suction part, and if it has continuous pores, it becomes a ventilation part. Hereinafter, each functional unit and the like will be described.

(Conductive part)
When the functional part is a conductive part, the conductive part is preferably a combination of a polymer matrix and a conductive filler, or a metal.

Examples of the case where the conductive portion is a metal include those composed of a metal layer (metal foil). Examples of the material used for the metal layer include aluminum, copper, silver, gold, platinum, palladium, nickel, iron, and alloys containing these as main components. Further, it is also possible to use a base material made of these materials plated with gold, silver, nickel or the like, or a material in which a dustproof layer, a primer or the like is laminated. Of these, copper or aluminum is preferably used from the viewpoint of price and availability.

When the conductive portion is a combination of the polymer matrix and the conductive filler, the polymer matrix described in the heat conductive portion can be used.
Examples of the conductive filler include fillers such as aluminum, silver, copper, gold, platinum, palladium, nickel, iron, alloys containing these as main components, and conductive carbon. In addition, a filler in which particles made of metal or resin are coated with the metal can be mentioned. Examples of the shape of the filler include spherical, polyhedral, flaky, fibrous, and amorphous powders, and the above-mentioned ones may be used alone or two or more thereof may be used in combination.

The average particle size of the conductive filler is preferably 1 to 200 μm, more preferably 5 to 100 μm. When the average particle size is 200 μm or less, precipitation of the conductive filler can be easily suppressed and a uniform conductive portion can be easily formed. Further, by setting the average particle size to 1 μm or more, the viscosity increase when a large amount of the conductive filler is filled in the precursor of the polymer matrix is small, and the conductive portion can be easily formed.
When the conductive filler is fibrous, the length of its major axis is preferably 50 to 500 μm. When the length of the major axis is 500 μm or less, the viscosity increase when a large amount of the conductive filler is filled in the precursor of the polymer matrix is small, and the conductive portion can be easily formed. Further, the resistance value can be lowered by setting the length of the long axis to 50 μm or more.
The average particle size or the length of the major axis of the conductive filler can be measured by observing with an electron microscope or the like. More specifically, the particle size of 50 arbitrary conductive fillers is measured using an electron microscope, an optical microscope, and an X-ray CT device in the same manner as the measurement with the anisotropic filler, and the average value thereof. (Arithmetic mean value) can be used as the average particle size. Further, the length of the long axis of the fibrous conductive filler can be measured in the same manner, and the average value (arithmetic mean value) can be used as the average length.

The content of the conductive filler in the functional part is preferably 25 to 80% by volume, more preferably 30 to 75% by volume. The content of the polymer matrix is preferably 20 to 75% by volume, more preferably 25 to 70% by volume, based on the functional portion.

Regardless of the combination of the polymer matrix and the conductive filler and the case where the conductive part contains a metal, the heat conduction with respect to the width WA of one heat conduction layer from the viewpoint of the balance between the heat conductivity and the conductivity. The ratio of the width WB (WB / WA) of the conductive layer to be the conductive portion adjacent to the layer is preferably 0.001 to 0.5. Further, when the conductive portion is a metal layer, it is more preferably 0.001 to 0.1, and when the conductive portion is a combination of a polymer matrix and a conductive filler, 0.02 to 0 It is more preferably .5.
The above ratio can be adjusted by adjusting the thickness of the heat conductive primary sheet or the functional member to be laminated, which will be described later.

Further, the width WB of the conductive layer is preferably 1 to 500 μm. When the conductive portion is a metal layer, it is particularly preferably 1 to 20 μm. On the other hand, when the conductive portion is a combination of the polymer matrix and the conductive filler, it is particularly preferably 5 to 200 μm. The distance between the conductive layers sandwiching the heat conductive layer is preferably 300 μm to 5 mm (however, the distance is within the range of the WB / WA). With the above width and spacing, a sufficient conductive path can be obtained in the thickness direction.

(Electromagnetic wave absorber)
When the functional part is an electromagnetic wave absorbing part, the electromagnetic wave absorbing part is preferably a combination of a polymer matrix and an electromagnetic wave absorbing filler, or a metal.

Examples of the case where the conductive portion is a metal include a metal wire and a metal layer. The metal wire is used when the functional portion as shown in FIG. 2 has a dot shape. Examples of the metal layer include those composed of metal foil. Examples of the metal of the metal wire and the metal layer include metals or compounds containing at least one element selected from iron, nickel and cobalt. Of these, carbonyl iron is preferable as the metal of the metal wire and the metal layer.

When the electromagnetic wave absorbing portion is a combination of the polymer matrix and the electromagnetic wave absorbing filler, the polymer matrix described in the heat conductive portion can be used.
Examples of the electromagnetic wave absorbing filler include magnetic powders such as ferrite, sendust, carbonyl iron, and electromagnetic stainless steel.
Examples of the shape of the electromagnetic wave absorbing filler include spherical, polyhedral, flaky, and amorphous powders, and the above-mentioned ones may be used alone or in combination of two or more. Among them, a flaky shape is preferable from the viewpoint of improving the electromagnetic wave absorption characteristics by increasing the proportion of the skin portion described later.

The average particle size of the electromagnetic wave absorbing filler is preferably 1 to 200 μm, more preferably 30 to 160 μm. By setting the average particle size to 200 μm or less, the occupancy ratio of the portion other than the epidermis (core portion) that is not involved in the attenuation of electromagnetic noise to the epidermis portion (approximately several μm) of the filler that is involved in the attenuation of electromagnetic noise. The radio wave absorption characteristics can be efficiently improved by preventing the signal from becoming too large. Further, when the average particle size is 1 μm or more, it is easy to highly fill the filler and the electromagnetic wave absorption characteristics can be improved.
The average particle size of the electromagnetic wave absorbing filler can be measured by observing with an electron microscope or the like. More specifically, the particle size of 50 arbitrary electromagnetic wave absorbing fillers is measured using an electron microscope, an optical microscope, and an X-ray CT device in the same manner as the measurement with the anisotropic filler, and the average thereof is measured. The value (arithmetic mean value) can be the average particle size. When measuring the particle size, the length of the major axis shall be measured for the filler having an aspect ratio.

The content of the electromagnetic wave absorbing filler in the functional part is preferably 25 to 90% by volume, more preferably 40 to 85% by volume, based on the functional part. When the volume is 25% by volume or more, the electromagnetic wave absorption becomes good. On the other hand, when the volume is 90% by volume or less, the functional portion can be easily compressed without impairing the flexibility. The content of the polymer matrix is preferably 10 to 75% by volume, more preferably 15 to 60% by volume, based on the functional portion.

Regardless of the combination of the polymer matrix and the electromagnetic wave absorbing filler and the case where the electromagnetic wave absorbing portion contains a metal, from the viewpoint of the balance between the thermal conductivity and the electromagnetic wave absorbing property, the width WA of the heat conductive layer is 1. The ratio of the width WB (WB / WA) of the electromagnetic wave absorbing layer to be the electromagnetic wave absorbing portion adjacent to the heat conductive layer is preferably 0.05 to 0.5, and is 0.1 to 0.5. Is more preferable.
The above ratio can be adjusted by adjusting the thickness of the heat conductive primary sheet or the functional member to be laminated, which will be described later.

The width WB of the electromagnetic wave absorbing layer is preferably 1 to 500 μm, and the distance between the electromagnetic wave absorbing layers sandwiching the heat conductive layer is 300 μm to 5 mm (however, the distance is within the range of the WB / WA). ) Is preferable. With the above width and spacing, sufficient electromagnetic wave absorption can be obtained.

(Flame-retardant part)
When the functional part is a flame-retardant part, the flame-retardant part is preferably a combination of a polymer matrix and a flame-retardant filler. As the polymer matrix, the one described in the heat conductive section can be used.
Examples of the flame-retardant filler include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and hydrotalcite, red phosphorus, triphenyl phosphate (triphenyl phosphate), and tricre. Various phosphate esters such as dizyl phosphate, trixylenyl phosphate, cresildiphenyl phosphate, and xylenyl diphenyl phosphate, metal phosphates such as sodium phosphate, potassium phosphate, and magnesium phosphate, sodium phosphite, It is also possible to use metal phosphite salts such as potassium phosphite, magnesium phosphite, aluminum phosphite, ammonium polyphosphate, boron-based compounds and the like. These may be used alone or in combination of two or more.

Among the above, metal hydroxide is preferable, and aluminum hydroxide is more preferable, from the viewpoint of enhancing thermal conductivity and application to silicone resin.

The average particle size of the flame-retardant filler is preferably 1 to 200 μm, more preferably 1 to 60 μm. When the average particle size of the flame-retardant filler is within the above range, the dispersibility of the flame-retardant filler is improved, the flame-retardant filler is uniformly dispersed in the resin, and the flame-retardant filler is filled with the resin. The blending amount of the material can be increased.
The average particle size of the flame retardant is a value of the median diameter (D50) measured by a laser diffraction / scattering type particle size distribution measuring device.

The content of the flame retardant filler in the functional part depends on the type of the flame retardant, but in the case of metal hydroxide, it is preferably in the range of 150 to 1200 parts by mass with respect to 100 parts by mass of the polymer matrix. More preferably, it is in the range of 300 to 800 parts by mass. When the amount is 150 parts by mass or more, the flame retardancy is improved. On the other hand, when the amount is 1200 parts by mass or less, the functional part can be easily compressed without impairing the flexibility.
The content of the flame-retardant filler is preferably 10 to 85% by volume, more preferably 30 to 80% by volume, based on the functional portion. The content of the polymer matrix is preferably 15 to 60% by volume, more preferably 20 to 50% by volume, based on the functional portion.

From the viewpoint of the balance between thermal conductivity and flame retardancy, the flame-retardant portion is the ratio of the width WB of the flame-retardant layer adjacent to the thermal conductive layer to the width WA of 1 thermal conductive layer. (WB / WA) is preferably 0.05 to 0.5, more preferably 0.1 to 0.5.
The above ratio can be adjusted by adjusting the thickness of the heat conductive primary sheet or the functional member to be laminated, which will be described later.

The width WB of the flame-retardant layer is preferably 200 to 2500 μm, and the distance between the flame-retardant layers sandwiching the heat conductive layer is preferably 300 μm to 5 mm. With the above width and spacing, sufficient flame retardancy can be obtained.

A heat conductive filler or other functional filler can be added to the flame-retardant layer as long as the flame retardancy exhibited by the flame-retardant layer is not impaired.

(Adsorption part)
When the functional part is a suction part, the suction part is preferably a combination of a polymer matrix and an adsorptive filler. As the polymer matrix, the one described in the heat conductive section can be used.
The adsorption part suppresses the generation by adsorbing the low molecular weight siloxane generated by the decomposition of the heat conductive part and the silicone which is the polymer matrix of the adsorbed part, and by adsorbing other impurities generated from the inside of the sheet. .. It is also possible to adsorb components generated in the external environment.
Examples of the adsorptive filler include zeolite, silica gel, activated carbon, and porous powder of a styrene / divinylbenzene copolymer.

The average particle size of the adsorptive filler is preferably 1 to 500 μm, more preferably 5 to 200 μm. By setting the average particle size to 500 μm or less, the surface (surface area) of the filler that contributes to adsorption can be prevented from becoming too small, and a predetermined adsorption force can be easily exerted. Further, by setting the average particle size to 1 μm or more, the filler can be highly filled and a predetermined adsorptivity can be exhibited.
The average particle size of the adsorptive filler can be measured by observing it with an electron microscope or the like. More specifically, the particle size of 50 arbitrary adsorptive fillers is measured using an electron microscope, an optical microscope, and an X-ray CT device in the same manner as in the measurement with the anisotropic filler, and the average value thereof is measured. (Arithmetic mean value) can be used as the average particle size.

The content of the adsorptive filler in the functional part is preferably 0.5 to 30% by volume, more preferably 2 to 20% by volume, based on the functional part. When the content is 0.5% by volume or more, the adsorptivity is improved. On the other hand, when it is 30% by volume or less, the viscosity of the composition before curing does not become too high, and the functional portion can be easily formed. In the case of a porous adsorptive filler, the content is a value calculated from the volume of the filler based on the outer shape of the particles and the volume of the polymer matrix excluding the permeation into the filler. Further, the volume% can be calculated by measuring the area occupied by the adsorptive filler or the volume occupied by the adsorptive filler in an arbitrary cross section using an electron microscope, an optical microscope, or an X-ray CT apparatus.
The content of the polymer matrix is preferably 70 to 99.5% by volume, more preferably 80 to 98% by volume, based on the functional portion.

From the viewpoint of the balance between thermal conductivity and adsorptivity, the ratio (WB / WA) of the width WB of the adsorption layer to be the adsorption part adjacent to the heat conductive layer to the width WA of 1 heat conductive layer is , 0.01 to 0.5, more preferably 0.05 to 0.5.
The above ratio can be adjusted by adjusting the thickness of the heat conductive primary sheet or the functional member to be laminated, which will be described later.

The width WB of the adsorption layer is preferably 5 to 500 μm, and the distance between the adsorption layers sandwiching the heat conductive layer is preferably 300 μm to 5 mm. With the above width and spacing, sufficient adsorptivity can be obtained.

(Ventilation part)
When the functional part is a ventilation part, it is preferable that the ventilation part has continuous pores. The continuous pores can impart functions such as air cooling and waste heat to the heat conductive sheet. In order to form continuous pores, it is preferable to use a porous layer (foamed sheet) having continuous pores.
Examples of the foamed sheet include a silicone foamed sheet, a polyurethane foamed sheet, a synthetic rubber or natural rubber foamed sheet, a polyolefin foamed sheet, and a polystyrene foamed sheet. From the viewpoint of air cooling, waste heat, etc., the open cell ratio is preferably 40% or more, more preferably 50 to 90%.
When the functional part is a ventilation part, the polymer matrix corresponds to a resin constituting the foam sheet, that is, silicone, polyurethane, synthetic rubber, natural rubber, polyolefin, polyolefin-based elastomer, polystyrene, polystyrene-based elastomer, or the like. .. Among these, silicone, polyurethane, synthetic rubber, natural rubber, polyolefin-based elastomer, and styrene-based elastomer are preferable from the viewpoint of increasing flexibility, and silicone having excellent integration with a heat conductive portion, heat resistance, and weather resistance is particularly preferable. ..

The continuous porosity (communication rate) is a value measured using an air comparison hydrometer 1000 type (manufactured by Tokyo Science Co., Ltd.) according to the method described in ASTM D-2856-87, and can be obtained by the following formula. it can.
Open cell ratio (%) = (apparent volume-volume measured by air comparative hydrometer) / apparent volume x 100
The apparent volume can be calculated from the external dimensions of various foam sheets.

The pore size of the continuous pores is not particularly limited, but specifically, it is preferably about 0.5 to 500 μm. In the present invention, the pore diameter of continuous pores can be obtained by measuring the pore diameters of any 50 continuous pores in the observation cross section of various foam sheets by SEM and averaging them.

From the viewpoint of the balance between heat conductivity and air permeability, the ratio (WB / WA) of the width WB of the foam sheet to be the ventilation part adjacent to the heat conductive layer to the width WA of 1 heat conductive layer is , 0.02 to 0.5, more preferably 0.06 to 0.2. When the foamed sheet is made into a heat conductive sheet, continuous pores are formed in the thickness direction thereof.

Further, the width WB of the foamed sheet serving as the ventilation portion is preferably 100 to 1000 μm, and the distance between the electromagnetic wave absorbing layers sandwiching the heat conductive layer is preferably 300 μm to 5 mm. With the above width and spacing, sufficient air permeability can be obtained.

(Additional ingredients)
In the heat conductive part and the functional part as described above, various additives may be blended as long as the function as the heat conductive sheet according to the present embodiment is not impaired. Examples of the additive include at least one selected from a dispersant, a coupling agent, a pressure-sensitive adhesive, a flame retardant, an antioxidant, a colorant, an antioxidant and the like. Further, when the curable silicone composition is cured as described above, a curing catalyst or the like that accelerates the curing may be blended as an additive. Examples of the curing catalyst include platinum-based catalysts.

(Characteristics of Thermal Conductive Sheet)
The thermal conductivity in the thickness direction z in the heat conductive portion of the heat conductive sheet 100 is, for example, 5 W / (m · K) or more, preferably 7 W / (m · K) or more, preferably 9 W / (m · K) or more. -K) The above is more preferable. By setting these lower limits or more, the thermal conductivity of the heat conductive sheet 100 in the thickness direction z can be made excellent. Although there is no particular upper limit, the thermal conductivity of the heat conductive sheet 100 in the thickness direction z is, for example, 50 W / (m · K) or less. The thermal conductivity shall be measured by a method based on ASTM D5470-06.

When the functional portion of the thermally conductive sheet 100 is a conductive portion made of a metal layer, the volume resistivity of the conductive portion in the thickness direction z ^{is preferably 10-7} to 10 ^-1 Ω · cm. More preferably, it is ^-7 to 10 ^{-4 Ω · cm.} When the functional part of the thermally conductive sheet 100 is a conductive part formed by a combination of a polymer matrix and a conductive filler, the volume resistivity of the conductive part in the thickness direction z is 10 ^-4 to 10 ^6. It is preferably Ω · cm, and more preferably ^{10 -4} to ^{-1 Ω · cm.} The volume resistivity can be measured by the method described in Examples. Further, the volume resistivity of the heat conductive sheet 100 is preferably a value obtained by multiplying the volume resistivity of the conductive portion by (WA + WB) / WB.

When the functional part of the heat conductive sheet 100 is an electromagnetic wave absorbing part, the magnetic permeability (1 MHz) as an electromagnetic wave characteristic in the thickness direction z of the electromagnetic wave absorbing part is preferably 2 to 200, preferably 5 to 100. More preferably. The magnetic loss (1 GHz) is preferably 0.1 to 30, more preferably 0.5 to 20. The electromagnetic wave characteristics can be measured by the method described in the examples.

When the functional part of the heat conductive sheet 100 is a flame retardant part, the flame retardancy of the heat conductive sheet is a combustion test (UL94) established by Under Writer's Laboratories Inc. of the United States. ), It is preferable to provide V-0.

When the functional part of the heat conductive sheet 100 is a flame-retardant part, it is preferable that the heat absorption amount Q of the heat conductive sheet from 150 ° C. to 350 ° C. is 500 J / cm ^{3 or more.} By doing so, not only the ignition of the heat conductive sheet itself is suppressed, but also, for example, when an abnormality occurs in the cell of the lithium ion battery, the heat generation is suppressed and the ignition is prevented. In order to obtain the heat absorption amount, for example, flame-retardant portions containing 70% by volume of aluminum hydroxide may be laminated so that the ratio (WB / WA) is 0.22 or more.

When the functional part of the heat conductive sheet 100 is a ventilation part, the air permeability measured by the breathability A method (Frazier method) specified in JIS L1096 shall be 0.001 to ⁵ cm 3 / cm ² · s. Is preferable.

Further, the type E hardness of the heat conductive sheet 100 is, for example, 70 or less. The heat conductive sheet has a type E hardness of 70 or less, so that flexibility is ensured. For example, the followability to a heating element and a heat radiating body is improved, and the heat radiating property tends to be good. The type E hardness of the thermally conductive sheet 100 is preferably 40 or less from the viewpoint of improving the flexibility and improving the followability and the like. More preferably, the type OO hardness is 50 or less.
The lower limit of the hardness of the thermally conductive sheet 100 is not particularly limited, but is, for example, 15 or more, preferably 25 or more for the type OO hardness. Further, it is particularly preferable that the type E hardness is 20 or more. The softer the hardness of the heat conductive sheet, the smaller the stress on the heating element, the heat radiating element, the substrate on which they are placed, etc. when compressed, but the hardness is set to 15 or more for the type OO hardness. As a result, the heat conductive sheet 100 can be provided with a predetermined handleability. Further, when the E hardness is 20 or more, the balance between handleability and softness can be excellent.
The type E hardness and the type OO hardness are values measured using a predetermined durometer according to the method specified in ASTM D2240-05.

In the present embodiment, the anisotropic filler 14 is exposed on both sides 100A and 100B of the heat conductive sheet 100. Further, the exposed anisotropic filler 14 may protrude from each of the double-sided 100A and 100B. In the heat conductive sheet 100, the anisotropic filler 14 is exposed on both sides 100A and 100B, so that both sides 100A and 100B become non-adhesive surfaces. Since the heat conductive sheet 100 has both sides 100A and 100B as cut surfaces by cutting with a cutting tool described later, the anisotropic filler 14 is exposed on both sides 100A and 100B.
However, either one or both of the double-sided 100A and 100B may be an adhesive surface without exposing the anisotropic filler 14.

The thickness of the heat conductive sheet 100 is appropriately changed according to the shape and application of the electronic device on which the heat conductive sheet 100 is mounted. The thickness of the heat conductive sheet 100 is not particularly limited, but may be used in the range of, for example, 0.1 to 5 mm.
The thickness of each heat conductive layer 13A is not particularly limited, but is preferably 0.3 to 5.0 mm, more preferably 0.5 to 3.0 mm. The thickness of the heat conductive layer 13A is the length of the unit layer 13 along the stacking direction x of the single layer 13. The thickness of each functional layer 13B is preferably 0.001 to 2.5 mm. When each functional layer is a metal layer, it is more preferably 0.001 to 0.02 mm. On the other hand, when each functional layer is a combination of a polymer matrix and a filler, it is more preferably 0.006 to 2500 mm.

The heat conductive sheet 100 is used inside an electronic device or the like. Specifically, the heat conductive sheet 100 is interposed between the heating element and the heat radiating element, conducts heat generated by the heating element, transfers the heat to the radiating element, and dissipates heat from the radiating element. Here, examples of the heating element include various electronic components such as a CPU, a power amplifier, and a power supply used inside an electronic device. Examples of the radiator include a heat sink, a heat pump, and a metal housing of an electronic device. The heat conductive sheet 100 is used with both sides 100A and 100B in close contact with each of the heating element and the heat radiating element and compressed.

In particular, the heat conductive sheet whose functional part is a conductive part is preferably arranged between a metal housing or a heat sink and a heating element including a ground electrode, and by doing so, static electricity is generated or isolated. It is effective in suppressing noise caused by metal bodies. Further, it is preferable that the heat conductive sheet whose functional part is an electromagnetic wave absorbing part is an element or the like that generates an electromagnetic wave that causes noise as well as heat generation.
The heat conductive sheet whose functional part is a flame-retardant part is preferably used by being attached to a heating element such as a battery for which ignition countermeasures are desired, and the heat conductive sheet whose functional part is a suction part is heat. It is preferable to use it for optical parts where gas volatilized from the conductive sheet or gas in the atmosphere is a problem, and the thermal conductive sheet whose functional part is a ventilation part is used for both heat dissipation by a heat sink and air cooling. It is preferable to be used in.

<Manufacturing method of heat conductive sheet>
Next, an example of the above-mentioned method for manufacturing the heat conductive sheet will be described.
This manufacturing method includes a step of preparing a plurality of thermally conductive primary sheets, each containing a polymer matrix and a thermally conductive filler, and a polymer matrix, a conductive filler, and an electromagnetic wave absorbing filler, respectively. , A combination with any of a flame-retardant filler, an adsorptive filler, and continuous pores, or a step of preparing a plurality of functional members containing a metal, and laminating the plurality of primary sheets with the plurality of functional members. By doing so, a step of adhering to form a laminated block and a step of cutting the laminated block into a sheet shape along the laminating direction to obtain a thermally conductive sheet are provided. Hereinafter, each step will be described in detail.

(Thermal conductivity primary sheet preparation process)
In the heat conductive primary sheet preparation step, first, the liquid composition is formed into a sheet while applying a shearing force to obtain a heat conductive primary sheet. The liquid composition includes a resin that is a precursor of the polymer matrix (for example, in the case of a silicone resin, a curable silicone composition), an anisotropic filler, and the like. The liquid composition may be further blended with a non-anisotropic filler as appropriate, or may be further blended with an additive component. The liquid composition is usually a slurry. For mixing the components constituting the liquid composition, for example, a known kneader, kneading roll, mixer or the like may be used.

Here, the viscosity of the liquid composition is preferably 100 to 10,000 Pa · s. When the viscosity is 50 Pa · s or more, a shearing force is applied in the alignment treatment step to form a sheet while flowing the filler, so that the long axis direction Y of the anisotropic filler is changed to the flow direction (in the sheet surface direction). It becomes easier to orient in the direction along (one direction). Further, when the value is 10,000 Pa · s or less, the coatability is improved. From these viewpoints, the viscosity of the liquid composition is more preferably 300 to 3000 Pa · s, and even more preferably 400 to 2000 Pa · s.
The viscosity is the viscosity measured at a rotation speed of 1 rpm or 10 rpm using a rotational viscometer (Brookfield viscometer DV-E, spindle SC4-14), and the measured temperature is at the time of coating the liquid composition. The temperature of. More specifically, if the viscosity is 300 Pa · s or less when measured at a rotation speed of 10 rpm, the measured value can be adopted, and when the viscosity exceeds 300 Pa · s when measured at a rotation speed of 10 rpm, the measured value can be adopted. , The measured value at a rotation speed of 1 rpm can be adopted. Further, when the temperature at the time of coating is unknown, the measured value at 25 ° C. can be adopted.

The viscosity of the liquid composition can be adjusted by the type and amount of the above-mentioned heat conductive filler. Further, it can be appropriately adjusted depending on each component constituting the resin. For example, when the liquid composition is a curable silicone composition, the molecular weight of each component (alkenyl group-containing organopolysiloxane, organohydrogenpolysiloxane, etc.) constituting the curable silicone composition should be appropriately adjusted. Then, the above viscosity may be used. Further, the liquid composition may contain an organic solvent as needed to adjust the viscosity, but it is preferable that the liquid composition does not contain an organic solvent.

When molding the liquid composition into a sheet, it is preferable to coat the liquid composition on the base film by, for example, a coating applicator such as a bar coater or a doctor blade, extrusion molding, or ejection from a nozzle. A shearing force can be applied along the coating direction (flow direction) of the liquid composition. By forming the sheet into a sheet while applying a shearing force in this way, the anisotropic filler is oriented so that the major axis direction (fiber axis direction) is along the flow direction (one direction in the sheet surface direction).

Next, the liquid composition formed into a sheet is cured, dried, or the like as necessary to obtain a thermally conductive primary sheet. In the thermally conductive primary sheet, as described above, the long axis of the anisotropic filler is unidirectionally oriented in the plane direction.
Further, the curing of the liquid composition is performed by curing the curable silicone composition, for example, when the liquid composition contains a curable silicone composition. The liquid composition may be cured by heating, but for example, it may be performed at a temperature of about 50 to 150 ° C. The heating time is, for example, about 10 minutes to 3 hours. When a solvent is mixed with the curable liquid composition, the solvent may be volatilized by heating during curing.

The thickness of the heat conductive primary sheet obtained by curing is preferably in the range of 0.1 to 5.0 mm. By setting the thickness of the thermally conductive primary sheet within the above range, as described above, the anisotropic filler can be appropriately oriented along the plane direction by the shearing force. Further, by setting the thickness of the heat conductive primary sheet to 0.1 mm or more, it can be easily peeled off from the base film. Further, by setting the thickness of the heat conductive primary sheet to 5.0 mm or less, a heat conductive primary sheet having high orientation of the anisotropic filler can be obtained. From these viewpoints, the thickness of the heat conductive primary sheet is more preferably 0.3 to 3.0 mm, still more preferably 0.5 to 2.5 mm.

(Functional member preparation process)
In the functional member preparation step, when the functional member is a combination of the polymer matrix and any of the conductive filler, the electromagnetic wave absorbing filler, the flame-retardant filler, and the adsorptive filler, it is as follows. .. First, the liquid composition is molded into, for example, a sheet while applying a shearing force to obtain a functional member. The liquid composition includes a resin that is a precursor of a polymer matrix (for example, a curable silicone composition in the case of a silicone resin), a conductive filler, an electromagnetic wave absorbing filler, a flame retardant filler, and an adsorptive property. Includes any of the fillers and the like. The liquid composition may be further blended with a non-anisotropic filler as appropriate, or may be further blended with an additive component. The liquid composition is usually a slurry. For mixing the components constituting the liquid composition, for example, a known kneader, kneading roll, mixer or the like may be used.

Here, the viscosity of the liquid composition is preferably 10 to 10000 Pa · s from the viewpoint of handleability.
The viscosity of the liquid composition can be adjusted by the type and amount of the above-mentioned various fillers. Further, it can be appropriately adjusted depending on each component constituting the resin. For example, when the liquid composition is a curable silicone composition, the molecular weight of each component (alkenyl group-containing organopolysiloxane, organohydrogenpolysiloxane, etc.) constituting the curable silicone composition should be appropriately adjusted. Then, the above viscosity may be used. Further, the liquid composition may contain an organic solvent as needed to adjust the viscosity, but it is preferable that the liquid composition does not contain an organic solvent.

When molding the liquid composition into a sheet, for example, a coating applicator such as a bar coater or a doctor blade, extrusion molding, ejection from a nozzle, screen printing or other printing method, stretching roll, or the like is used. It may be coated or formed on a material film. Among these, when forming a functional layer of a thin film of 0.3 mm or less, a coating applicator such as a bar coater or a doctor blade is used using a liquid composition having a relatively low viscosity of about 10 to 150 Pa · s. Alternatively, it is preferable to coat the substrate film by screen printing or other printing methods. On the other hand, when forming a functional layer of a thick film exceeding 0.3 mm, a liquid composition of 50 Pa · s or more is used, and the functional layer is formed on the base film by extrusion molding, ejection from a nozzle, or a stretch roll. It is preferable to form.

Next, the liquid composition formed into a sheet is cured, dried, or the like as necessary to obtain a functional member.
Further, the curing of the liquid composition is performed by curing the curable silicone composition, for example, when the liquid composition contains a curable silicone composition. The liquid composition may be cured by heating, but for example, it may be performed at a temperature of about 50 to 150 ° C. The heating time is, for example, about 10 minutes to 3 hours. When a solvent is mixed with the curable liquid composition, the solvent may be volatilized by heating during curing.

The sheet thickness of the functional member obtained by curing is preferably in the range of 0.006 to 2.5 mm from the viewpoint of handleability.

When the functional member is a combination of a polymer matrix and continuous pores, it is preferable to prepare a porous layer (porous sheet) having the above-mentioned continuous pores. The thickness of the perforated sheet is preferably in the range of 100 to 1000 mm. More preferably, it is 200 to 600 mm.

When the functional member is a combination of a polymer matrix and any of a conductive filler, an electromagnetic wave absorbing filler, a flame-retardant filler, an adsorptive filler, and continuous pores, the shape is a sheet. However, it may be linear in order to form a dot-shaped functional portion as shown in FIG. The diameter in the linear case is preferably in the range of 0.006 to 2.5 mm.

When the functional member contains metal, the metal wire described above and the metal foil to be the metal layer are prepared. The diameter of the metal wire is preferably in the range of 0.001 to 0.02 mm. The thickness of the metal foil is preferably in the range of 0.001 to 0.02 mm.

(Laminating process)
Next, the plurality of thermally conductive primary sheets 17 obtained in the preparatory step and the plurality of functional members 20 or 21 are laminated so that the orientation directions of the anisotropic fillers are the same (FIG. 6). And FIG. 7). That is, one direction along the major axis direction of the above-mentioned anisotropic filler is laminated so as to coincide with each other among the plurality of thermally conductive primary sheets. Then, the plurality of laminated heat conductive primary sheets 17 and the plurality of functional members are alternately adhered to each other and integrated to obtain a laminated block 18. For example, when the resin of each laminated sheet is a thermoplastic resin, it is preferable to melt and fix the polymer matrix in each sheet by press molding to form a laminated block 18. Further, a known adhesive or the like may be arranged between the sheets to adhere them.
Further, when the precursor of the polymer matrix is curable, a plurality of semi-cured sheets are laminated, and after the lamination, each sheet is completely cured, and the sheets are adhered to each other and integrated by the total curing. The laminated block 18 may be used.

Further, when the polymer matrix is a silicone resin or the like, it is preferable to irradiate at least one surface of the heat conductive primary sheet with vacuum ultraviolet rays. That is, at least one surface of the obtained thermally conductive primary sheet is irradiated with VUV to activate at least one surface, and the surface between the thermally conductive primary sheets 17 and 17 is activated. It may be adhered. The VUV is a vacuum ultraviolet ray, and means an ultraviolet ray having a wavelength of 10 to 200 nm. Examples of the VUV light source include an excimer Xe lamp and an excimer ArF lamp.

When the heat conductive primary sheet contains, for example, a silicone resin (organopolysiloxane) as described above, when VUV is irradiated, the surface irradiated with VUV is activated. As will be described later, the heat conductive primary sheet can be combined with the heat conductive primary sheet by superimposing the activated one surface so as to be a superposed surface so as to be in contact with the functional member. The functional member will be firmly adhered. Although the principle is not clear, in the silicone resin, when VUV is irradiated, the C—Si bond of the organopolysiloxane changes to the Si—O bond such as Si—OH, and the Si—O bond causes the silicone resin. It is presumed that the heat conductive primary sheet and the functional member are firmly adhered to each other. That is, the heat conductive primary sheet and the functional member are adhered by forming a bond between the molecules of the organopolysiloxane. Further, by adhering by VUV irradiation, the flexibility in the direction perpendicular to the laminating direction is not significantly impaired.
The VUV irradiation condition is not particularly limited as long as it can activate the surface of the heat conductive primary sheet, but for example, the integrated light amount is 5 to 100 mJ / cm ² , preferably the integrated light amount is 10 to 50 mJ / cm ^2. It is advisable to irradiate VUV as described above.

Here, each of the heat conductive primary sheets 17 may be subjected to VUV irradiation in advance on any one of the overlapping surfaces in contact with the functional member. Since one surface is irradiated with VUV, the heat conductive primary sheet and the functional member are adhered to each other by the activated one surface. Further, from the viewpoint of further improving the adhesiveness, it is preferable that both the overlapping surfaces are irradiated with VUV.
That is, as shown in FIG. 6A, the heat conductive primary sheet 17 may be superposed so that one surface 17A irradiated with VUV is in contact with the functional member 20 or 21. It is preferable that the overlapped portion of the functional member 20 in contact with one surface 17A is also irradiated with VUV.

By VUV irradiation, the heat conductive primary sheet and the functional member can be adhered only by overlapping as described above, but in order to bond more firmly, the heat conductive primary sheet and the functional member are adhered in the laminating direction. You may pressurize. The pressurization is preferably performed at a pressure such that the heat conductive primary sheet and the functional member are not significantly deformed, and can be pressurized by using, for example, a roller or a press. As an example, when a roller is used, the pressure is preferably 0.3 to 3 kgf / 50 mm.
The laminated heat conductive primary sheet and functional member may be appropriately heated, for example, when pressurizing, but the heat conductive primary sheet and functional member activated by VUV irradiation are not heated. It is preferable that the laminated heat conductive primary sheet and the functional member are not heated because they can also be adhered to each other. Therefore, the temperature at the time of pressing is, for example, 0 to 50 ° C, preferably about 10 to 40 ° C.

Even when the functional member is linear, the laminated block can be formed by laminating and adhering the functional member in the same manner as when the functional member is sheet-shaped. That is, as shown in FIG. 7A, the functional members 21 can be arranged, laminated and adhered between the heat conductive primary sheet and the heat conductive primary sheet at predetermined intervals.

(Cutting process)
Next, as shown in FIGS. 6 (B) and 7 (B), the laminated block 18 is cut along the laminating direction of the heat conductive primary sheet and the functional member by the cutting tool 19, and FIGS. 1 and 2 The heat conductive sheet 100 shown in the above is obtained. At this time, the laminated block 18 may be cut in a direction orthogonal to one direction along the long axis direction of the anisotropic filler. As the blade 19, for example, a double-edged blade such as a razor blade or a cutter knife, a single-edged blade, a round blade, a wire blade, a saw blade, or the like can be used. The laminated block 18 is cut by using a cutting tool 19, for example, by a method such as pushing, shearing, rotating, or sliding.

[Second Embodiment]
Next, the heat conductive sheet of the second embodiment of the present invention will be described with reference to FIG.
In the first embodiment, the heat conductive portion 13A of the heat conductive sheet 100 contains the non-anisotropic filler 15 in addition to the anisotropic filler 14 as the thermally conductive filler. As shown in FIG. 4, the heat conductive sheet 200 of the embodiment contains the non-anisotropic filler 15 without the anisotropic filler 14. That is, each heat conductive portion 23A of the heat conductive sheet of the second embodiment does not contain the anisotropic filler 14, but contains the non-anisotropic filler 15.

The other configuration of the heat conductive sheet 200 of the second embodiment is the same as that of the heat conductive sheet 100 of the first embodiment described above, except that the anisotropic filler is not contained. Is omitted.

Also in this embodiment, high thermal conductivity is exhibited by the heat conductive portion, and other functions such as conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, or air permeability of the functional portion are also exhibited satisfactorily. To.

[Third Embodiment]
Next, the heat conductive sheet of the third embodiment of the present invention will be described with reference to FIG.
In the first embodiment, the heat conductive portion of the heat conductive sheet 100 contains the non-anisotropic filler 15 in addition to the anisotropic filler 14 as the heat conductive filler. As shown in FIG. 5, the thermally conductive sheet 300 in the form does not contain a non-anisotropic filler. That is, each heat conductive portion 33A of the heat conductive sheet of the second embodiment contains an anisotropic filler 14 oriented in the thickness direction of the sheet 30, but the non-anisotropic filler 15 Is not contained.

Since the present embodiment does not contain an anisotropic filler, the content of the non-anisotropic filler 15 is preferably 30 to 85% by volume, preferably 40 to 85% by volume, based on the total amount of the heat conductive portion. 80% by volume is more preferable.

The other configuration of the heat conductive sheet 300 of the third embodiment is the same as that of the heat conductive sheet 100 of the first embodiment described above, except that the non-anisotropic filler is not contained. The description is omitted.

Also in this embodiment, high thermal conductivity is exhibited by the heat conductive portion, and other functions such as conductivity, electromagnetic wave absorption, flame retardancy, adsorptivity, or air permeability of the functional portion are also exhibited satisfactorily. To.

The heat conductive sheet of the present invention is not limited to the configuration of the first to third embodiments, and can have various aspects.

In the above description, each of the heat conductive parts and the functional parts of the heat conductive sheet has substantially the same composition, but the composition of each layer may be different from each other.
For example, in the above description, all the heat conductive parts in the heat conductive sheet contained the heat conductive filler, but at least one heat conductive part contained the heat conductive filler, and the other parts. The layer may not contain a thermally conductive filler. In such a case, various configurations such as the heat conductive filler, the silicone resin, and the heat conductive sheet are provided in the first to first steps, except that some of the heat conductive parts do not contain the heat conductive filler. Since it is as described in the third embodiment, the description thereof will be omitted. Further, in the manufacturing method, at least one primary sheet among the plurality of primary sheets may contain a heat conductive filler, and the other primary sheets may not contain the heat conductive filler.

Further, for example, in the first embodiment, all the heat conductive portions contain both an anisotropic filler and a non-anisotropic filler, but some of the heat conductive portions are anisotropic. It may contain both an anisotropic filler and a non-anisotropic filler, and a part of the heat conductive portion may contain either an anisotropic filler or a non-anisotropic filler.
Further, for example, some heat conductive portions may have only an anisotropic filler, and some heat conductive portions may have only a non-anisotropic filler 15.
Further, each heat conductive part does not have to have the same content of the heat conductive filler, and the content of the heat conductive filler in some heat conductive parts is changed to the heat conduction in the other heat conductive parts. It may be different from the content of the sex filler. Further, the type of the heat conductive filler in some heat conductive parts may be different from the type of the heat conductive filler in other heat conductive parts.

As described above, by appropriately adjusting the presence / absence, content, type, etc. of the heat conductive filler in each heat conductive part, the thermal conductivity of some of the heat conductive parts can be changed to other heat conduction. It may be made higher than the thermal conductivity of the part. In such a case, the heat conductive portion having a high thermal conductivity and the heat conductive portion having a low thermal conductivity may be arranged alternately, but it is not necessary to arrange them alternately.

Of course, the configuration of each functional unit may be changed for each layer. That is, the types and amounts of the conductive filler, the electromagnetic wave absorbing filler, the flame-retardant filler, and the adsorptive filler may be appropriately different.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

In this example, the physical characteristics of the heat conductive sheet were evaluated by the following method.
[Thermal conductivity]
The thermal conductivity of the thermal conductivity sheet was measured by a method according to ASTM D5470-06.

[Permeability]
The magnetic permeability of each sheet was measured using an RF impedance / material analyzer "HP 4291B" manufactured by Agilent Technologies for a sample prepared by punching the sheet into a ring shape having an outer diameter of 20 mm and an inner diameter of 5 mm.

[Magnetic loss]
The magnetic loss of each sheet is measured by a vector network analyzer "VNA MasterTM MS2026A" (manufactured by Anritsu Co., Ltd.) and a measurement program "S parameter method coaxial tube reflection measurement program (measurement frequency band: 500 MHz to 3 GHz), coaxial tube type measurement kit: It was measured by the coaxial tube method using an outer diameter of φ7 mm and an inner diameter of φ3 mm (manufactured by Keycom Co., Ltd.).

[Dielectric breakdown voltage]
The breakdown voltage, which is an index for evaluating the insulation property, was measured by using a withstand voltage tester (TOS8650, manufactured by Kikusui Electronics Co., Ltd.) by partially modifying the method based on JIS K6249. Specifically, after sandwiching a test piece of each sheet having a thickness of 2 mm between two electrodes made of brass having a cylindrical shape with a test outer shape of φ20 mm, the compression ratio becomes 10% (thickness of 1.8 mm). It was placed in a compressed state so that it would be. Subsequently, a voltage is applied between the electrodes, and the voltage is gradually increased. At this time, the current suddenly increased, and a part of the test piece melted and became perforated or carbonized to be energized. The voltage at this time was recorded as the dielectric breakdown voltage. Five test pieces were prepared and tested five times, and the arithmetic mean value was used.

[Volume resistivity]
The volume resistivity was calculated from the measured area and the thickness of the test piece by measuring the resistance value in a state where each sheet was compressed by 10% with the following testing machine. The testing machine used for the test was a pair of electrodes (gold-plated) with a constant current source (“6146” manufactured by ADC) and a voltage logger (“Remote Scanner Jr. DC3100” manufactured by A & D Co., Ltd.) having a diameter of 10 mm. It is connected to the aluminum electrode). A constant current source and a voltage logger are electrically connected to each electrode, and when a test piece (each sheet) is compressed by the electrode, a circuit for measuring the resistance of the sheet is formed by the voltage logger. .. At this time, the current of the circuit is fixed to 50 mA by a constant current source, and the resistance value R of the sheet is obtained by dividing the value of the voltage (mV) read by the voltage logger by the value of the fixed current (50 mA). (Ω) was calculated. _{Further, the volume resistivity ρ V} was calculated from the following formula based on the cross-sectional area S and the thickness L of the test piece.
ρ _V = R × S / L
At this time, the area S is 0.79 cm ² and the thickness L is 0.18 cm.

[E hardness]
The type E hardness (E hardness) was a value measured using a predetermined durometer according to the method specified in ASTM D2240-05. More specifically, by stacking five sheets having a thickness of 2 mm, a test piece having a thickness of 10 mm and an outer shape of 20 mm × 20 mm was prepared. Then, the hardness of the test piece was measured at five different points, and the arithmetic mean value was taken as the hardness of each sheet.

[Example 1]
As a curable silicone composition, an alkenyl group-containing organopolysiloxane (main agent) and a hydrogen organopolysiloxane (curing agent) (total 100 parts by mass, volume filling rate 37% by volume) and graphite as an anisotropic filler. 120 parts by mass (volume filling rate 20% by volume) of carbon fiber (average fiber length 200 μm, aspect ratio 20, thermal conductivity 400 W / m · K), and aluminum oxide powder (spherical, average particle size) as a non-anisometric filler 3 μm, aspect ratio 1.0) 450 parts by mass (volume filling rate 43% by volume) were mixed to obtain a slurry-like liquid composition. The viscosity of the liquid composition at 25 ° C. was 300 Pa · s (rotation speed 10 rpm).

The above liquid composition was unidirectionally coated on a base film made of polyethylene terephthalate (PET) at 25 ° C. using a bar coater as a coating applicator. The anisotropic filler had a major axis oriented in the coating direction and a minor axis oriented in the normal direction of the coated surface. Next, the applied liquid composition was heated at 120 ° C. for 0.5 hours to cure the liquid composition, thereby obtaining five heat conductive primary sheets (12 mm × 12 mm) having a thickness of 2 mm. It was.

As a curable silicone composition, an alkenyl group-containing organopolysiloxane (main agent) and a hydrogen organopolysiloxane (curing agent) (total 100 parts by mass, volume filling rate 38% by volume), and water as a non-anisometric filler. 70 parts by mass (volume filling rate 11% by volume) of aluminum oxide powder (atypical, average particle size 10 μm) and 700 parts by mass (volume) of magnetic powder (soft ferrite, amorphous, average particle size 180 μm) as an electromagnetic wave absorbing filler The filling ratio (31% by volume) was mixed to obtain a slurry-like liquid composition. The viscosity of the liquid composition at 25 ° C. was 100 Pa · s (rotation speed 10 rpm).

The above liquid composition was unidirectionally coated on a base film made of polyethylene terephthalate (PET) at 25 ° C. using a bar coater as a coating applicator. Next, the applied liquid composition is heated at 120 ° C. for 0.5 hours to cure the liquid composition, thereby forming four sheet-shaped functional members (12 mm × 12 mm) having a thickness of 0.5 mm. Obtained.

Of the obtained heat conductive primary sheets, a VUV irradiation device (trade name: Excimer MINI, manufactured by Hamamatsu Photonics Co., Ltd.) was used for two sheets on one side and three sheets on both sides. Then, VUV was irradiated to each surface of the heat conductive primary sheet in the air at room temperature (25 ° C.) under ^{the condition of an integrated light amount of 20 mJ / cm 2.}

Next, a functional member, a heat conductive primary sheet irradiated with VUV on both sides, a functional member, and heat irradiated with VUV on both sides of a heat conductive primary sheet irradiated with VUV on one side. The conductive primary sheet, the functional member, the thermally conductive primary sheet irradiated with VUV on both sides, the functional member, and the surface irradiated with VUV of the thermally conductive primary sheet irradiated with VUV on one side are brought into contact in this order. Then, they were laminated and adhered to each other, and pressed with a roller at a pressure of 1.6 kgf / 50 mm in an environment of 25 ° C. to obtain a laminated block. The obtained laminated block was sliced by a cutter blade parallel to the lamination direction and perpendicular to the orientation direction of the anisotropic filler to obtain a heat conductive sheet having a thickness of 2 mm and a thickness of 12 mm × 12 mm.
There were five linear heat conductive parts exposed on one surface, and the width of one was 2 mm. There were four radio wave absorbing parts, which are linear functional parts exposed on one surface, and the width of one was 0.5 mm.
For the above-mentioned thermal conductivity sheet (Example 1), the thermal conductivity, the magnetic permeability as electromagnetic wave characteristics, and the magnetic loss were measured. The results are shown in Table 1.
Further, a sheet in which only the heat conductive primary sheet was laminated was produced in the same manner as in Example 1 except that the functional member was a heat conductive primary sheet (Comparative Example 1). Further, a sheet in which only the functional members were laminated was produced in the same manner as in Example 1 except that the thermal conductivity primary sheet was used as the functional member (Comparative Example 2). The magnetic conductivity and the magnetic loss were measured. The results are shown in Table 1.

The heat conductive sheet of Example 1 had a thermal conductivity of 14 W / m · K, which was a slight decrease as compared with Comparative Example 1 in which only the heat conductive portion was formed. In addition, Example 1 also had good electromagnetic wave absorption characteristics such as magnetic permeability and magnetic loss.

(Example 2)
As a curable silicone composition, alkenyl group-containing organopolysiloxane (main agent) and hydrogen organopolysiloxane (curing agent) (total 100 parts by mass, volume filling rate 34% by volume), and oxidation as a non-anisometric filler. Aluminum powder (spherical, average particle size 70 μm, aspect ratio 1.0) 50 parts by mass (volume filling rate 13% by volume), aluminum oxide powder (spherical, average particle size 3 μm, aspect ratio 1.0) 50 parts by mass (volume) Filling rate 13% by volume) 50 parts by mass, aluminum hydroxide powder (atypical, average particle size 70 μm) 200 parts by volume (volume filling rate 29% by volume), and aluminum hydroxide powder (atypical, average particle size 10 μm) 200 Parts by volume (volume filling rate: 29% by volume) were mixed to obtain a slurry-like liquid composition. The viscosity of the liquid composition at 25 ° C. was 80 Pa · s (rotation speed 10 rpm).

The above liquid composition was unidirectionally coated on a base film made of polyethylene terephthalate (PET) at 25 ° C. using a bar coater as a coating applicator. The anisotropic filler had a major axis oriented in the coating direction and a minor axis oriented in the normal direction of the coated surface. Next, the applied liquid composition was heated at 120 ° C. for 0.5 hours to cure the liquid composition, thereby obtaining five heat conductive primary sheets (12 mm × 12 mm) having a thickness of 2 mm. It was.

Aluminum foil (thickness 0.006 mm) was prepared as a functional member.

Of the obtained heat conductive primary sheets, a VUV irradiation device (trade name: Excimer MINI, manufactured by Hamamatsu Photonics Co., Ltd.) was used for two sheets on one side and three sheets on both sides. Then, VUV was irradiated to each surface of the heat conductive primary sheet in the air at room temperature (25 ° C.) under ^{the condition of an integrated light amount of 20 mJ / cm 2.}

Next, a functional member, a heat conductive primary sheet irradiated with VUV on both sides, a functional member, and heat irradiated with VUV on both sides of a heat conductive primary sheet irradiated with VUV on one side. The conductive primary sheet, the functional member, the thermally conductive primary sheet irradiated with VUV on both sides, the functional member, and the surface irradiated with VUV of the thermally conductive primary sheet irradiated with VUV on one side are brought into contact in this order. Then, they were laminated and adhered to each other, and pressed with a roller at a pressure of 1.6 kgf / 50 mm in an environment of 25 ° C. to obtain a laminated block. The obtained laminated block was sliced vertically parallel to the laminating direction with a cutter blade to obtain a heat conductive sheet having a thickness of 2 mm and a thickness of 12 mm × 12 mm.
There were five linear heat conductive parts exposed on one surface, and the width of one was 2 mm. There were four conductive parts, which are linear functional parts exposed on one surface, and the width of one was 0.006 mm.
For the thermal conductivity sheet (Example 2), the thermal conductivity, the breakdown voltage, the volume resistivity, and the E hardness were measured. The results are shown in Table 2.
Further, a sheet in which only the heat conductive primary sheet was laminated was produced in the same manner as in Example 2 except that the functional member was a heat conductive primary sheet (Comparative Example 3). Further, a sheet in which only the functional members were laminated was produced in the same manner as in Example 2 except that the thermal conductivity primary sheet was used as the functional member (Comparative Example 4). The resistivity and E hardness were measured. The results are shown in Table 2.

From the comparison between Example 2 and Comparative Examples 3 and 4, it was found that the heat conductive sheet of Example 2 has conductivity while having the same hardness and thermal conductivity as Comparative Example 3. It was.

10 Thermal Conductive Sheet 13A Thermal Conductive Part, Thermal Conductive Layer 13B Functional Part, Functional Layer

Claims (13)

A plurality of heat conductive parts including a polymer matrix and a heat conductive filler,
Thermal conductivity including a combination of a polymer matrix and any of a conductive filler, an electromagnetically absorbing filler, a flame retardant filler, an adsorptive filler, and continuous pores, or a plurality of functional parts containing a metal. It ’s a sex sheet,
A heat conductive sheet in which the heat conductive portion and the functional portion are flush with each other on the front surface and the back surface of the heat conductive sheet. The heat conductive sheet according to claim 1, wherein the heat conductive portion and the functional portion are alternately laminated in the plane direction. The heat conductive portion is a heat conductive layer extending linearly in a predetermined direction on each of the front surface and the back surface of the heat conductive sheet.
The heat conductive sheet according to claim 1 or 2, wherein the functional part is a functional layer extending parallel to the heat conductive layer or a dot-shaped functional part intermittently arranged in parallel with the heat conductive layer. The heat conductive sheet according to any one of claims 1 to 3, wherein the heat conductive filler contains an anisotropic filler. The heat conductive sheet according to any one of claims 1 to 4, wherein the heat conductive filler contains a non-anisotropic filler. The heat conductive sheet according to claim 4 or 5, wherein the anisotropic filler is oriented in the thickness direction of the sheet. The heat conductive sheet according to any one of claims 4 to 6, wherein the anisotropic filler is at least one selected from a fibrous material and a scaly material. The heat conductive sheet according to claim 7, wherein the normal direction of the scale surface of the scaly material is oriented in the stacking direction of the plurality of heat conductive layers. The heat conductive sheet according to any one of claims 1 to 8, wherein the adjacent heat conductive portion and the functional portion are directly fixed to each other. A step of preparing a plurality of thermally conductive primary sheets, each containing a polymer matrix and a thermally conductive filler, and
A combination of a polymer matrix and any of a conductive filler, an electromagnetic wave absorbing filler, a flame-retardant filler, an adsorptive filler, and continuous pores, or a plurality of functional members containing a metal are prepared. Process and
A step of forming a laminated block by adhering the plurality of primary sheets and the plurality of functional members by laminating them.
A step of cutting the laminated block so as to form a sheet along the laminating direction to obtain a heat conductive sheet.
A method for manufacturing a thermally conductive sheet. After preparing a plurality of the heat conductive primary sheets, a step of irradiating at least one surface of the heat conductive primary sheets with vacuum ultraviolet rays is provided.
In the step of forming the laminated block, the plurality of thermally conductive primary sheets are laminated so that one surface irradiated with vacuum ultraviolet rays is in contact with the functional member, thereby adhering the laminated block. The method for producing a heat conductive sheet according to claim 10, wherein the heat conductive sheet is formed. The thermally conductive filler contains an anisotropic filler, and in the thermally conductive primary sheet, the anisotropic filler is oriented along the plane direction thereof.
The method for producing a heat conductive sheet according to claim 10 or 11, wherein the laminated block is cut in a direction orthogonal to the direction in which the anisotropic filler is oriented. The method for producing a thermally conductive sheet according to any one of claims 10 to 12, wherein the thermally conductive filler contains a non-anisotropic filler.

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