JP2022050296A - Thermal conductive sheet and method for producing sheet - Google Patents

Abstract

To provide a thermal conductive sheet that is excellent in chemical resistance, water- and oil-repellency, heat resistance, electric characteristics or the like, in particular, excellent in adhesion, thermal conductivity (heat-dissipating properties), electric characteristics and excoriation resistance.SOLUTION: A thermal conductive sheet has: a base sheet layer that is composed of a polymer composition containing a hot-meltable tetrafluoroethylene polymer and a thermal conductive filler; and an adhesive resin layer directly provided on at least one surface of the base sheet layer. The tetrafluoroethylene polymer has an oxygen-containing polar group or the polymer composition includes a composite particle of the tetrafluoroethylene polymer and the thermal conductive filler.SELECTED DRAWING: None

Description

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

In recent years, in order to reduce the size and improve the performance of electronic devices, it has been required to increase the output of motors. High-performance electronic devices and high-power motors tend to generate more heat due to electrical resistance and friction, and methods for removing these heat are being studied.
As a method for removing heat, a method using an adhesive heat conductive sheet is known. Patent Documents 1 and 2 describe, as the heat conductive sheet, a base sheet layer containing a tetrafluoroethylene polymer having excellent heat resistance and electrical properties and a heat conductive filler, and an adhesive layer containing a silicone composition. The sheet to have is described.

Japanese Unexamined Patent Publication No. 2013-86433. International Publication 2014/10327

The tetrafluoroethylene polymer is non-adhesive, and it is difficult for the base sheet layer and the adhesive layer to adhere sufficiently. Even in the sheets described in Patent Documents 1 and 2, the peel strength of both layers is not yet sufficient, and further improvement is required.
Further, the present inventors tend to aggregate the heat conductive filler in the base sheet layer containing the tetrafluoroethylene polymer and the heat conductive filler, and the uniformity tends to decrease, thereby only reducing the heat dissipation. Not only that, it was found that the mechanical properties such as bendability also deteriorated.

As a result of diligent studies, the present inventors obtained a sheet having excellent peel strength, thermal conductivity and mechanical properties when a predetermined tetrafluoroethylene polymer or a predetermined composite particle was used as the base sheet layer. I found out that it is possible.
An object of the present invention is to provide a heat conductive sheet having such physical characteristics and a method for manufacturing the sheet.

The present invention has the following aspects.
<1> It has a base sheet layer made of a polymer composition containing a heat-meltable tetrafluoroethylene polymer and a heat conductive filler, and an adhesive resin layer directly provided on at least one surface of the base sheet layer. , The heat conductive sheet, wherein the tetrafluoroethylene polymer has an oxygen-containing polar group, or the polymer composition comprises composite particles of the tetrafluoroethylene polymer and the heat conductive filler.
<2> The tetrafluoroethylene-based polymer contains units based on perfluoro (alkyl vinyl ether), and contains 1 to 5 mol% of units based on perfluoro (alkyl vinyl ether) with respect to all units, and has a melting temperature of 260 to 320 ° C. The heat conductive sheet of <1> above, which is a tetrafluoroethylene-based polymer.
<3> The heat conductive sheet according to <1> or <2>, wherein the composite particles are composite particles having the tetrafluoroethylene polymer as a core and the heat conductive filler on the surface of the core.
<4> The thermally conductive filler is silicon oxide, aluminum oxide, lead oxide, iron oxide, tin oxide, magnesium oxide, titanium oxide, zinc oxide, antimony pentoxide, zirconium oxide, lanthanum oxide, neodium oxide, cerium oxide, etc. The heat conductive sheet according to any one of <1> to <3> above, which is a heat conductive filler containing at least one selected from the group consisting of niobium oxide, boron nitride and aluminum nitride.
<5> The thermally conductive sheet according to any one of <1> to <4> above, wherein the thermally conductive filler is a thermally conductive filler containing aluminum oxide or boron nitride.
<6> The heat conductive sheet according to any one of <1> to <5> above, wherein the shape of the heat conductive filler is scaly or spherical.
<7> The heat transferable sheet according to any one of <1> to <6>, wherein the pressure-sensitive adhesive resin layer is made of a silicone composition.
<8> The ratio of the content of the heat conductive filler to the total content of the tetrafluoroethylene polymer and the heat conductive filler in the base sheet layer is 0.05 or more. A heat conductive sheet according to any one of 1> to <7>.
<9> The heat conductive sheet according to any one of <1> to <8>, wherein the heat conductive sheet has a thickness of 1 to 1000 μm.
<10> The heat conductive sheet according to any one of <1> to <9>, wherein the ratio of the thickness of the pressure-sensitive adhesive resin layer to the base sheet layer is 0.01 to 5.
<11> The heat conductive sheet according to any one of <1> to <10>, which has the adhesive resin layer on both sides of the base sheet layer.
<12> A liquid polymer composition containing heat-meltable tetrafluoroethylene polymer particles and a heat-conductive filler and a liquid dispersion medium is applied to a substrate and heated to obtain the tetrafluoroethylene polymer and the heat. A sheet layer containing a conductive filler is formed, an adhesive resin composition is directly applied to the surface of the sheet layer to form an adhesive resin layer, and the base material is removed to form the sheet layer and the sheet layer. A method for manufacturing a sheet, which obtains a sheet having the adhesive resin layer provided directly on the surface.
<13> The production method of <12> above, wherein the liquid dispersion medium is one kind of liquid dispersion medium selected from the group consisting of amides, ketones and esters.
<14> The method for producing <12> or <13>, wherein the tetrafluoroethylene polymer particles have an average particle size of 0.1 to 10 μm.
<15> Two sheets having a sheet layer containing a heat-meltable tetrafluoroethylene polymer and the heat conductive filler and an adhesive resin layer directly provided on one side of the sheet layer are prepared, and the two sheets are prepared. The sheets are arranged so as to face each other so that the sheet layers are in contact with each other, and thermocompression bonding is performed to integrate the two sheet layers to form a pressure-bonding sheet layer. A method for manufacturing a sheet, which obtains a sheet having the adhesive resin layer directly provided.

According to the present invention, a heat conductive sheet and a sheet having excellent peel strength and heat conductivity can be obtained.

The following terms have the following meanings.
The "tetrafluoroethylene-based polymer" is a polymer containing a unit based on tetrafluoroethylene, and is also simply referred to as "F polymer".
The "glass transition point (Tg) of the polymer" is a value measured by analyzing the polymer by the dynamic viscoelasticity measurement (DMA) method.
The “polymer melting temperature (melting point)” is the temperature corresponding to the maximum value of the melting peak measured by the differential scanning calorimetry (DSC) method.
“D50” is the average particle diameter of the particles or the filler, and is the volume-based cumulative 50% diameter of the particles obtained by the laser diffraction / scattering method. That is, the particle size distribution of the particles is measured by the laser diffraction / scattering method, the cumulative curve is obtained with the total volume of the particle population as 100%, and the particle size is the point where the cumulative volume is 50% on the cumulative curve.
“D90” is the cumulative volume particle size of the particles or the filler, and is the volume-based cumulative 90% diameter of the particles obtained in the same manner as in “D50”.
The "viscosity of the liquid polymer composition" is a value measured for the liquid polymer composition at room temperature (25 ° C.) and a rotation speed of 60 rpm using a B-type viscometer. The measurement is repeated 3 times, and the average value of the measured values for 3 times is used.
The "thixotropic ratio of the liquid polymer composition" is a value calculated by dividing the viscosity η ₁ measured under the condition of a rotation speed of 30 rpm by the viscosity η ₂ measured under the condition of a rotation speed of 60 rpm. The measurement of each viscosity is repeated 3 times, and the average value of the measured values for 3 times is used.
The "monomer-based unit" means an atomic group based on the above-mentioned monomer formed by polymerization of the monomer. The unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of the above unit is converted into another structure by processing a polymer. Hereinafter, the unit based on the monomer a is also simply referred to as “monomer a unit”.

The heat conductive sheet of the present invention (hereinafter, also referred to as “the present sheet”) is a base sheet layer composed of a polymer composition containing a heat-meltable F polymer and a heat conductive filler, and at least one of the base sheet layers. It has an adhesive resin layer provided directly on the surface, the F polymer has an oxygen-containing polar group, or the polymer composition comprises composite particles of the F polymer and a thermally conductive filler. The basesheet layer is a layer formed from the polymer composition.

The thermal conductivity of this sheet is preferably 1 to 100 W / m · K, more preferably 1 to 50 W / m · K, and even more preferably 3 to 25 W / m · K. In this sheet, the ratio of the thermal conductivity in the plane direction to the thermal conductivity in the thickness direction is preferably more than 1, more preferably 3 or more. The above ratio is more preferably 10 or less.
The peel strength of this sheet is preferably 5 N / cm or more, more preferably 10 N / cm or more. The upper limit of the peel strength of this sheet is 100 N / cm. The peel strength of this sheet is the peel strength between the layers of the base sheet layer and the adhesive resin layer.
The thickness of this sheet is preferably 1 to 1000 μm, more preferably 50 to 500 μm. The ratio of the thickness of the pressure-sensitive adhesive resin layer to the thickness of the base sheet layer is preferably 0.01 to 5, more preferably 0.05 to 1.

The reason why this sheet is excellent in peel strength between layers and mechanical properties such as thermal conductivity and bendability is not necessarily clear, but it is considered as follows.
The F polymer having an oxygen-containing polar group has a higher surface tension than the F polymer having no oxygen-containing polar group, and easily interacts with both the pressure-sensitive adhesive resin and the thermally conductive filler. In this sheet having a base sheet layer made of a polymer composition containing such an F polymer, the adhesiveness between the base sheet layer and the pressure-sensitive adhesive resin layer tends to be enhanced while the heat conductive filler is supported on the F polymer. As a result, it is considered that the mechanical properties of this sheet have improved. Further, it is considered that the heat conductivity of this sheet is improved because the aggregation of the heat conductive filler in the base sheet layer is suppressed.

On the other hand, in the composite particles of the F polymer and the heat conductive filler, the heat conductive filler is attached to the F polymer, and the aggregation is eliminated by this adhesion. Therefore, it is considered that the present sheet having the base sheet layer composed of the polymer composition containing such composite particles is formed from a state in which the heat conductive filler and the F polymer are densely mixed. As a result, it is considered that the heat conductive filler is uniformly dispersed in the base sheet layer, and the heat conductivity of this sheet is improved. In addition, it is considered that the stress distribution of this sheet becomes easier and the mechanical properties of this sheet are improved.

The F polymer in the present invention is a heat-meltable polymer containing a unit (TFE unit) based on tetrafluoroethylene (TFE).
The fluorine content of the F polymer is preferably 70 to 76% by mass. The F polymer having a high fluorine content is excellent in physical properties such as electrical properties.
The melting temperature of the F polymer is preferably 180 ° C. or higher, more preferably 200 ° C. or higher, and even more preferably 260 ° C. or higher. The melting temperature of the F polymer is preferably 325 ° C or lower, more preferably 320 ° C or lower. The melting temperature of the F polymer is particularly preferably 260 to 320 ° C.
The glass transition point of the F polymer is preferably 50 ° C. or higher, more preferably 75 ° C. or higher. The glass transition point of the F polymer is preferably 150 ° C. or lower, more preferably 125 ° C. or lower.

F polymers include low molecular weight polymers consisting only of TFE units (low molecular weight PTFE), polymers containing TFE units and ethylene-based units, polymers containing TFE units and propylene-based units, TFE units and perfluoro (alkyl). Polymers (PFA) containing units based on vinyl ether) (PAVE), polymers containing TFE units and units based on hexafluoropropylene (FEP), polymers containing TFE units and units based on fluoroalkylethylene. , TFE units and polymers based on chlorotrifluoroethylene are preferred, with PFA or FEP being preferred, and PFA being more preferred. The polymer may further contain units based on other comonomeres.
As the PAVE, CF ₂ = CFOCF ₃ , CF ₂ = CFOCF ₂ CF ₃ or CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter, also referred to as “PPVE”) is preferable, and PPVE is more preferable.

The number average molecular weight of the low molecular weight PTFE is preferably 10,000 to 200,000. In this case, PTFE has thermal meltability. The number average molecular weight of the low molecular weight PTFE is a value calculated based on the following formula (1).
Mn = 2.1 × 10 ¹⁰ × ΔHc- ^5.16 ... (1)
In the formula (1), Mn indicates the number average molecular weight of the low molecular weight PTFE, and ΔHc indicates the calorie of crystallization (cal / g) of the low molecular weight PTFE measured by the differential scanning calorimetry. The low molecular weight PTFE may contain a trace amount of units other than the TFE unit.

The F polymer preferably has an oxygen-containing polar group. The F polymer based on the oxygen-containing polar group has excellent physical properties such as adhesiveness, and easily interacts with the heat conductive filler and the adhesive resin layer.
The oxygen-containing polar group may be contained in the monomer unit in the F polymer, or may be contained in the terminal group of the main chain of the polymer. Examples of the latter aspect include an F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like.
The oxygen-containing polar group is preferably a hydroxyl group-containing group or a carbonyl group-containing group, and a carbonyl group-containing group is particularly preferable.
The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH or -C (CF ₃ ) ₂ OH.
The carbonyl group-containing group is a group containing a carbonyl group (> C (O)), a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC (O) NH ₂ ), and an acid anhydride residue. Group (-C (O) OC (O)-), imide residue (-C (O) NHC (O)-etc.) or carbonate group (-OC (O) O-) is preferred, and acid anhydride residue. Is more preferable.

As the F polymer, a polymer containing PAVE units and containing 1 to 5 mol% of PAVE units with respect to all units and having a melting temperature of 260 to 320 ° C. is preferable, and a monomer having PAVE units and an oxygen-containing polar group is used. More preferably, the polymer (1) containing the based unit or the polymer (2) having no oxygen-containing polar group containing 2 to 5 mol% of the PAVE unit with respect to all the monomer units. Since these polymers form microspherulites in the base sheet layer, the adhesiveness between the F polymer and the heat conductive filler and the pressure-sensitive adhesive resin layer is likely to be improved.

The polymer (1) is preferably a polymer containing a TFE unit, a PAVE unit, and a monomer having a hydroxyl group-containing group or a carbonyl group-containing group. The polymer (1) has 90 to 98 mol% of TFE units, 1.5 to 9.97 mol% of PAVE units, and 0.01 to 3 mol% of units based on the above-mentioned monomers, respectively, with respect to all the units. It is preferable to include it.
The monomer is preferably itaconic anhydride, citraconic anhydride or 5-norbornen-2,3-dicarboxylic acid anhydride (also known as hymic anhydride; hereinafter also referred to as "NAH").
Specific examples of the polymer (1) include the polymers described in International Publication No. 2018/16644.

The polymer (2) is composed of only TFE units and PAVE units, and preferably contains 95 to 98 mol% of TFE units and 2 to 5 mol% of PAVE units with respect to all the monomer units.
The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, based on all the monomer units.
The polymer (2) does not have oxygen-containing polar groups when the number of oxygen-containing polar groups contained in the polymer is less than 500 per 1 × 10 ⁶ carbon atoms constituting the polymer main chain. It means that there is. The number of oxygen-containing polar groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of oxygen-containing polar groups is usually 0.

The polymer (2) may be produced by using a polymerization initiator, a chain transfer agent, or the like that does not generate an oxygen-containing polar group as the terminal group of the polymer chain, and the F polymer having an oxygen-containing polar group is fluorinated. May be manufactured.
Examples of the fluorination treatment method include a method using fluorine gas (see JP-A-2019-194314).

The thermal conductivity of the thermally conductive filler in the present invention is preferably 1 W / mK or more, more preferably 100 W / mK or more. The thermal conductivity is preferably 300 W / mK or less.
The thermally conductive filler is preferably a filler containing an inorganic substance. As the inorganic substance, metal, metal oxide, and ceramic are preferable, and specifically, gold, silver, copper, platinum, nickel, palladium, aluminum oxide, lead oxide, iron oxide, tin oxide, magnesium oxide, titanium oxide, and oxidation. Zinc, antimony pentoxide, zirconium oxide, lanthanum oxide, neodium oxide, cerium oxide, niobium oxide, boron nitride, aluminum nitride, silicon nitride, graphite, carbon black, fullerene, aluminum hydroxide, silicon carbide, diamond, silicon oxide. Silicon oxide, aluminum oxide, lead oxide, iron oxide, tin oxide, magnesium oxide, titanium oxide, zinc oxide, antimony pentoxide, zirconium oxide, lanthanum oxide, neodium oxide, cerium oxide, niobium oxide, boron nitride or aluminum nitride. Is preferable, and aluminum oxide or boron nitride is more preferable.
As the heat conductive filler, one type may be used, or two or more types may be used.

The surface of the heat conductive filler is preferably surface-treated with a silane coupling agent, such as 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-glycidoxypropylmethyl. It is more preferable that the surface is treated with diethoxysilane, 3-methacryloxypropyltriethoxysilane, or 3-isoxapropyltriethoxysilane.

The D50 of the thermally conductive filler is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 20 μm or less. The D50 of the thermally conductive filler is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more. In this case, the thermally conductive filler is easily dispersed and does not easily fall off from the base sheet layer.
The heat conductive filler may have heat conduction anisotropy.
The shape of the thermally conductive filler may be granular, needle-like (fibrous), or plate-like. Specific shapes of the inorganic filler include spherical, scale-like, layered, flat plate-like, leaf-like, apricot kernel-like, columnar, chicken crown-like, equiaxed, leaf-like, mica-like, block-like, flat plate-like, wedge-like, and rosette. Examples include shape, mesh, and prismatic shape. The inorganic filler may be hollow or may contain a hollow filler and a non-hollow filler.

The thermally conductive filler is preferably scaly or spherical. Such a filler tends to have excellent dispersibility.
When the shape of the heat conductive filler is scaly, the heat conductive filler is likely to be oriented in the base sheet layer. In this case, a path of the heat conductive filler is formed, and this sheet is more likely to have excellent heat conductivity. When the heat conductive filler is a scaly anisotropic filler, it is preferable because the base sheet layer can be imparted with heat conduction anisotropy and the heat conductivity in the thickness direction of the present sheet can be improved.
The aspect ratio of the scaly heat conductive filler is preferably 5 or more, more preferably 10 or more. The aspect ratio is more preferably 1000 or less.
The heat conductive filler may be a mixture of a scaly heat conductive filler and a spherical heat conductive filler. In this case, the scaly heat conductive filler tends to be oriented, and this sheet tends to have excellent heat conductivity. Specific examples of such a thermally conductive filler include a mixture of a scaly filler containing boron nitride and a spherical filler containing aluminum oxide.

Suitable specific examples of the heat conductive filler include silica filler (“Admafine (registered trademark)” series manufactured by Admatex Co., Ltd.), zinc oxide surface-treated with an ester such as propylene glycol dicaprate (Sakai Chemical Industry Co., Ltd.). "FINEX (registered trademark)" series manufactured by Denka Co., Ltd.), spherical fused silica ("SFP (registered trademark)" series manufactured by Denka Co., Ltd., etc.), titanium oxide coated with polyhydric alcohol and inorganic substances (Ishihara Sangyo Co., Ltd.) "Typake (registered trademark)" series, etc.), rutile-type titanium oxide surface-treated with alkylsilane ("JMT (registered trademark)" series, etc. manufactured by Teika), hollow silica filler (manufactured by Pacific Cement Co., Ltd.) "E-SPHERES" series, "Sirinax" series manufactured by Nittetsu Mining Co., Ltd., "Ecocosfire" series manufactured by Emerson & Cumming, etc.), Tarkufiller ("SG" series manufactured by Nippon Tarku Co., Ltd., etc.), Steatite Fillers ("BST" series manufactured by Nippon Tarku Co., Ltd.), boron nitride fillers ("UHP" series manufactured by Showa Denko Co., Ltd., "Denka Boron Nitride" series ("GP", "HGP" grade) manufactured by Denka Co., Ltd., etc. ).

The polymer composition in this sheet contains an F polymer having an oxygen-containing polar group and a thermally conductive filler, or contains composite particles of the F polymer and the thermally conductive filler.
The polymer composition may contain only one of the F polymer having an oxygen-containing polar group or the composite particles, and may contain both the F polymer having an oxygen-containing polar group and the composite particles. Further, the F polymer in the composite particles may be an F polymer having an oxygen-containing polar group.

The F polymer having an oxygen-containing polar group contained in the polymer composition is preferably contained as particles of the F polymer having an oxygen-containing polar group (hereinafter, also referred to as “F particles”).
The F particles are particles containing an F polymer having an oxygen-containing polar group, and the amount of the F polymer having an oxygen-containing polar group in the F particles is preferably 80% by mass or more, more preferably 90% by mass or more. It is more preferably 100% by mass.
The D50 of the F particles is preferably 30 μm or less, more preferably 10 μm or less, further preferably 6 μm or less, and particularly preferably 3 μm or less. The D50 of the F particles is preferably 0.1 μm or more, more preferably 0.5 μm or more. The D90 of the F particles is preferably 10 μm or less, more preferably 8 μm or less. In this case, it is easy to form a dense base sheet layer.

The F particles may contain other resins different from the F polymer having an oxygen-containing polar group.
Examples of other resins include F polymers and aromatic polymers that do not have oxygen-containing polar groups. Examples of the aromatic polymer include aromatic polyimides, aromatic maleimides, aromatic elastomers such as styrene elastomers, and aromatic polyamic acids.

The composite particles contained in the polymer composition have an F polymer as a core, and an embodiment in which a thermally conductive filler is attached to the surface of the core of the F polymer (hereinafter, also referred to as “Aspect I”) and thermal conductivity. A mode in which the filler is used as a core and the F polymer is attached to the surface of the heat conductive filler is preferable, and mode I is more preferable. In the case of the aspect I, the heat conductive filler easily forms a path in the base sheet layer, and the present sheet tends to be excellent in heat conductivity. Here, the "core" means a core (central part) necessary for forming the particle shape of the composite particle, and does not mean the main component in the composition of the composite particle.

The deposit (heat conductive filler or F polymer) adhering to the surface of the core may be adhered only to a part of the surface of the core, or may be attached to most or the entire surface thereof. In the former case, it can be said that the deposits cling to the surface of the core like dust, in other words, a large part of the surface of the core is exposed. In the latter case, it can be said that the deposits are evenly sprinkled on the surface of the core or are in a state of covering the surface of the core, and such composite particles are formed from the core and the shell covering the core. It can be said that it has a core-shell structure.

In the case of Aspect I, the core of the F polymer is preferably composed of a single particle of the F polymer or an aggregate of particles of the F polymer. For the composite particles of the aspect I, it is preferable to set the D50 of the core of the F polymer to be larger than the D50 of the heat conductive filler and the amount of the F polymer to be larger than the amount of the heat conductive filler.
In the case of the aspect I, the D50 of the core of the F polymer is preferably 0.1 μm or more, more preferably 1 μm or more. The D50 of the core of the F polymer is more preferably 50 μm or less.
In the case of the aspect I, the D50 of the heat conductive filler is preferably 0.01 μm or more, more preferably 0.1 μm or more. The D50 of the thermally conductive filler is preferably 15 μm or less, more preferably 10 μm or less.

In the composite particle of the aspect I, the D50 of the thermally conductive filler is preferably 0.001 to 0.5, more preferably 0.01 to 0.3, based on the D50 of the core of the F polymer.
The D50 of the composite particle of the aspect I is preferably 70 μm or less, more preferably 50 μm or less. The D50 of the composite particle of the aspect I is preferably 1 μm or more, more preferably 20 μm or more.
The amount of the thermally conductive filler in the composite particles of the aspect I is preferably 1 part by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the F polymer. The upper limit is preferably 70 parts by mass, more preferably 50 parts by mass.
The shape of the thermally conductive filler in the composite particle of the aspect I is preferably spherical or scaly, and preferably scaly. In such a case, the thermally conductive filler tends to form a path in the base sheet layer, and the present sheet tends to have excellent thermal conductivity.
The thermally conductive filler may be embedded in the core of the F polymer.

The composite particles may be further surface-treated. Specific examples of such surface treatment include a method of surface-treating the composite particles of Embodiment I with siloxanes (polydimethylsiloxane or the like) or a silane coupling agent.
The composite particles are a method in which the particles of the F polymer and the thermally conductive filler are collided with each other at a temperature equal to or higher than the melting temperature of the F polymer and in a suspended state, and the particles of the F polymer and the thermally conductive filler are pressed or sheared. It is preferable to produce the liquid composition by a method of colliding the particles with the F polymer and a method of coagulating the particles of the F polymer by shearing the liquid composition containing the particles of the F polymer and the thermally conductive filler.

The polymer composition preferably contains F particles and composite particles. In this case, the composite particles tend to form a path for the thermally conductive filler, and the separately contained F particles tend to make the base sheet layer denser, so that this sheet tends to have excellent thermal conductivity and mechanical strength.
The ratio of D50 of F particles to D50 of composite particles is preferably 0.01 to 5, more preferably 0.03 to 1.
The ratio of the content of F particles to the content of composite particles in the polymer composition is preferably 0.1 to 5, more preferably 0.1 to 1.

The content of the F polymer in the polymer composition is preferably 10% by mass or more, more preferably 20% by mass or more. The content of the F polymer is preferably 95% by mass or less, more preferably 80% by mass or less.
The content of the thermally conductive filler in the polymer composition is preferably 1% by mass or more, more preferably 10% by mass or more. The content of the thermally conductive filler is preferably 90% by mass or less, more preferably 80% by mass or less.
The ratio of the content of the heat conductive filler to the content of the F polymer in the polymer composition is preferably 0.2 to 15, more preferably 1 to 10. In this case, the base sheet layer tends to be excellent in mechanical strength such as bendability and thermal conductivity.

The polymer composition may further contain other resins. The other resin may be thermosetting or may be a thermoplastic resin. As the other resin, a fluororesin other than the aromatic polymer and the F polymer is preferable.
Examples of the aromatic polymer include maleimide resin, urethane resin, polyimide, polyamic acid, polyamideimide, polyphenylene ether, polyphenylene oxide, liquid crystal polyester, and fluororesin other than F polymer.
Examples of the fluororesin different from the F polymer include non-heat-meltable PTFE.
The other resin may be contained separately from the F polymer and the thermally conductive filler in the polymer composition, and may be included as a composite with the F polymer or a composite with the thermally conductive filler. May be good. Examples of the composite include composite particles, and specific examples thereof include composite particles having a non-thermally meltable PTFE as a core and having a thermally conductive filler adhered to the surface of the core.

Polymer compositions also include dispersion media, thioxogenic agents, viscosity modifiers, defoamers, silane coupling agents, dehydrating agents, plasticizers, weather resistant agents, antioxidants, heat stabilizers, lubricants, antistatic agents. , Whitening agent, colorant, conductive agent, mold release agent, surface treatment agent, flame retardant, molding aid and the like.
The polymer composition may be liquid or powdery.

The pressure-sensitive adhesive resin layer in this sheet is a layer made of a pressure-sensitive adhesive resin composition, and is a layer formed of the pressure-sensitive adhesive resin composition. The pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive resin layer may be a resin or a precursor that forms the resin.
Examples of the adhesive resin include acrylic resin, olefin resin, polyurethane resin, polyester resin, silicone, natural rubber, and synthetic rubber. The adhesive resin may be thermosetting or thermoplastic. As the adhesive resin, acrylic resin or silicone is preferable from the viewpoint of thermal conductivity, and silicone is more preferable from the viewpoint of heat resistance. The pressure-sensitive adhesive resin layer in this sheet is preferably a layer made of a silicone composition containing silicone, in other words, a layer formed of the silicone composition.
As the adhesive resin, one type may be used, or two or more types may be used.

The acrylic resin is preferably an acrylic resin having a glass transition temperature of −20 ° C. or lower and a melt viscosity of 50 to 700 Pa · s. Specific examples of the acrylic resin include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-butyl (meth). ) A polymer of at least one (meth) acrylate selected from the group consisting of acrylates, isobutyl (meth) acrylates, methyl (meth) acrylates, ethyl (meth) acrylates and isopropyl (meth) acrylates.

The silicone is not particularly limited as long as it is a silicone that exhibits the tackiness of the pressure-sensitive adhesive resin layer, and is preferably a curing-reactive silicone, a silicone rubber, or a silicone resin. Silicone preferably has a viscosity at 70 ° C. of 400 Pa · s or less.
Examples of the curing reactive silicone include cross-linking reaction type silicone and addition reaction type silicone. Further, the curing reactive silicone may be contained as a partially cured product.
Examples of the silicone rubber include silicone rubber containing an organopolysiloxane having a phenyl group (particularly, an organopolysiloxane having methylphenylsiloxane as a main constituent unit). Various functional groups such as vinyl groups may be introduced into the organopolysiloxane in the silicone rubber, if necessary.
The silicone resin includes a unit consisting of the constituent unit "R ₃ SiO _1/2 ", a unit consisting of the constituent unit "SiO ₂ ", a unit consisting of the constituent unit "RSiO _3/2 ", and a constituent unit "R ₂ SiO". Examples thereof include silicone resins containing an organopolysiloxane composed of a (co) polymer having at least one unit selected from the group consisting of units consisting of. In addition, R in the said structural unit indicates a hydrocarbon group or a hydroxyl group.

The adhesive resin layer may contain a thermally conductive filler. The definition and scope of the thermally conductive filler in the pressure-sensitive adhesive layer is similar to that of the thermally conductive filler in the polymer composition, including preferred embodiments.
The thermally conductive filler in the pressure-sensitive adhesive layer may be the same as or different from the thermally conductive filler in the polymer composition.
The adhesive resin layer further includes a dispersion medium, a curing catalyst, a cross-linking agent, a filler, a plasticizer, an antiaging agent, an antistatic agent, a flame retardant-imparting agent, a surfactant, a colorant (pigment, dye, etc.) and the like. Additives may be included.
Specific examples of the pressure-sensitive adhesive resin composition forming the pressure-sensitive adhesive resin layer containing silicone include "PCS-TC-10", "PCS-TC-11", and "PCS-TC-20" manufactured by Shin-Etsu Chemical Co., Ltd. "SD4585PSA" manufactured by Toray Dow Corning Co., Ltd. can be mentioned. A curing catalyst may be further added to these compositions.

The thickness of the base sheet layer of this sheet is preferably 10 to 3000 μm, more preferably 30 to 1000 μm, and even more preferably 100 to 1000 μm. In this case, this sheet tends to have excellent low-line expansion and warpage is unlikely to occur.
The content of the F polymer in the base sheet layer is preferably 10% by mass or more, more preferably 20% by mass or more. The content of the F polymer is preferably 95% by mass or less, more preferably 80% by mass or less.
The content of the heat conductive filler in the base sheet layer is preferably 1% by mass or more, more preferably 10% by mass or more. The content of the thermally conductive filler is preferably 90% by mass or less, more preferably 80% by mass or less.
The ratio of the content of the heat conductive filler to the total content of the F polymer and the heat conductive filler in the base sheet layer is preferably 0.05 to 15, more preferably 1 to 10. In this case, the base sheet layer tends to be excellent in mechanical strength such as bendability and thermal conductivity.

The thickness of the pressure-sensitive adhesive resin layer of this sheet is preferably 0.1 to 300 μm, more preferably 1 to 200 μm. In this case, this sheet tends to have excellent thermal conductivity and peel strength.
The adhesive resin layer preferably contains 60% by mass or more of silicone, and more preferably 80% by mass or more.
In this sheet, the pressure-sensitive adhesive resin layer may be directly provided on at least one surface of the base sheet layer, and the pressure-sensitive adhesive resin layer may be directly provided on both sides of the base sheet layer. The adhesive resin layer is preferably provided directly on both sides of the base sheet layer. In this case, this sheet tends to have excellent adhesiveness.

Since this sheet has a base sheet layer containing an F polymer and a heat conductive filler and an adhesive resin layer, it has heat resistance, electrical characteristics, heat conductivity (heat dissipation), scratch resistance, and adhesion to other materials. Excellent physical properties such as properties and peeling strength. Therefore, this sheet is useful as an electronic board material such as a flexible printed wiring board and a rigid printed wiring board, a protective film and a heat dissipation board, and particularly as a heat dissipation board for automobiles.

This sheet can also be suitably used as a heat dissipation member of a wireless communication device. For example, in a wireless communication device having a base material made of resin or the like, an antenna pattern formed on the base material, and an RFIC package which is a power feeding circuit connected to the antenna pattern, the sheet may be arranged around the RFIC package. For example, it is possible to promote heat dissipation of the RFIC package and effectively suppress the temperature rise. In this case, from the viewpoint of not interfering with the radiation of the antenna, it is preferable to arrange this sheet on the surface of the RFIC package opposite to the surface on which the antenna pattern is provided. Examples of such wireless communication devices include the wireless communication devices described in International Publication No. 2020/008691 and International Publication No. 2020/031419.

This sheet is preferably manufactured by the sheet manufacturing method described below.
As a method for forming the base sheet layer of this sheet, in addition to the method for forming the sheet layer described below, a method for melt extrusion molding or injection molding of the above-mentioned powdery polymer composition can also be mentioned.

In the method for producing a sheet of the present invention (hereinafter, also referred to as "this method"), a liquid polymer composition containing F polymer particles, a heat conductive filler, and a liquid dispersion medium is applied to a substrate and heated. , F polymer and a sheet layer containing a heat conductive filler are formed, an adhesive resin composition is directly applied to the surface of the sheet layer to form an adhesive resin layer, and the base material is removed to form a sheet layer and a sheet layer. This is a method for obtaining a sheet having an adhesive resin layer made of an adhesive resin composition provided directly on the surface of the above.
The range of each of the F polymer, the particles of the F polymer, the heat conductive filler, the pressure-sensitive adhesive resin composition and the pressure-sensitive adhesive resin layer in this method is the same as the range in this sheet, including suitable embodiments. Further, the range of the base sheet layer in the present method is the same as the range of the base sheet layer in the present sheet, including the preferred embodiment.

The liquid polymer composition in this method is preferably the above-mentioned polymer composition containing a liquid dispersion medium.
The liquid dispersion medium is a dispersion medium that does not react with the F polymer. The boiling point of the liquid dispersion medium is preferably 75 ° C. or higher, more preferably 100 ° C. or higher. The boiling point of this dispersion medium is preferably 300 ° C. or lower, more preferably 250 ° C. or lower.
The liquid dispersion medium may be water or a non-aqueous dispersion medium, and at least one selected from the group consisting of amides, ketones and esters is preferable, and N-methyl-2-pyrrolidone and γ-butyrolactone are preferable. , Cyclohexanone or cyclopentanone is more preferred.

The content of the liquid dispersion medium in the liquid polymer composition is preferably 40% by mass or more, more preferably 60% by mass or more. The content of the liquid dispersion medium is preferably 90% by mass or less, more preferably 80% by mass or less.
The liquid dispersion medium may be one kind or a mixture of two or more kinds. The liquid dispersion medium is preferably degassed from the viewpoint of reducing the uniformity of the component distribution of the molded product obtained from the liquid polymer composition and suppressing voids.

The liquid polymer composition may further contain a surfactant from the viewpoint of improving dispersibility. Examples of the surfactant include an acetylene-based surfactant, a silicone-based surfactant, and a fluorine-based surfactant.
The viscosity of the liquid polymer composition at 25 ° C. is preferably 50 to 5000 mPa · s, more preferably 100 to 1000 mPa · s. The thixotropic ratio of the polymer composition is preferably 1 to 2.5, more preferably 1.2 to 2. In this case, the liquid polymer composition tends to be excellent in dispersibility and handleability.

The coating in this method is spray method, roll coat method, spin coat method, gravure coat method, micro gravure coat method, gravure offset method, knife coat method, kiss coat method, bar coat method, die coat method, fountain Mayer bar method, slot. It can be carried out by a method such as the die coat method.
The heating in this method may be performed in one step at a constant temperature, or may be performed in two or more steps at different temperatures. For the formation of the sheet layer from the liquid polymer composition, it is preferable to remove the liquid dispersion medium and then further calcin the F polymer to form a melt-fired product of the F polymer. In this case, the sheet layer tends to be dense.

The temperature for removing the liquid dispersion medium is preferably a temperature equal to or lower than the boiling point of the liquid dispersion medium, and more preferably a temperature 50 to 150 ° C. lower than the boiling point. It is preferable to blow air in the step of removing the liquid dispersion medium.
The firing temperature of the F polymer is preferably 300 to 400 ° C.
Examples of the heating method include a method using an oven, a method using a ventilation drying furnace, and a method of irradiating heat rays such as infrared rays.
The heating may be performed under either normal pressure or reduced pressure.

The sheet layer may be further pressure-molded. Examples of the pressure molding treatment include a treatment of pressing at a temperature equal to or higher than the thermal melting point of the F polymer and a pressure of 0.05 to 50 MPa for 1 to 15 minutes. In this case, the base sheet layer becomes dense, and the flexibility and thermal conductivity of the sheet of this method are likely to be further improved.
The surface of the sheet layer may be roughened from the viewpoint of improving the adhesiveness with the adhesive resin layer. Specific examples of the roughening treatment include plasma treatment, corona treatment, sputter etching treatment, ion etching treatment, sandblasting treatment, and alkali etching treatment.
Further, the sheet layer may be formed as a laminated body having a plurality of layers.

As the base material in this method, a resin film or a metal foil is preferable, and a release resin film (fluororesin film, a resin film having a release layer, etc.), copper, a copper alloy, stainless steel, nickel, and a nickel alloy (42 alloy) are preferable. Also included), aluminum, aluminum alloys, and aluminum is preferred. A rust preventive layer (oxide film such as chromate), a heat resistant layer, a roughening treatment layer, and a silane coupling agent treatment layer may be provided on the surface of the metal foil.
The thickness of the base material is preferably 1 to 3000 μm, more preferably 5 to 100 μm.

Examples of the method for forming the pressure-sensitive adhesive resin layer in this method include a method in which a sheet made of a pressure-sensitive adhesive resin composition is directly pressure-bonded to the surface of the sheet layer, and a method in which the pressure-sensitive adhesive resin composition is directly applied to the surface of the sheet layer. The adhesive resin composition may be heated before or after crimping or coating, or may be partially cured. Examples of the pressure-sensitive adhesive resin composition include liquid compositions containing the above-mentioned pressure-sensitive adhesive resin, which can be prepared by combining commercially available products.
Further, in forming the pressure-sensitive adhesive resin layer, a pressure-sensitive adhesive resin layer may be formed on the surface of another base material, and the pressure-sensitive adhesive resin layer and the sheet layer may be brought into contact with each other for pressure bonding.
The removal of the base material in this method is preferably performed by etching the base material after forming the adhesive resin layer, or by peeling off the base material. The base material may be removed after the sheet of this method is formed.

Both wet etching and dry etching can be used for etching. When the base material layer is a metal foil, the metal foil is preferably removed by etching, and more preferably removed by wet etching. In this case, wet etching is preferably performed using an acid solution.
If the F polymer has an oxygen-containing polar group, it is activated by the acid solution, so that the adhesiveness of the sheet layer after the metal foil is removed is more likely to be enhanced. Here, as an example of activation of the oxygen-containing polar group, conversion of an acid anhydride group into a 1,2-dicarboxylic acid group can be mentioned. An inorganic acid aqueous solution such as hydrochloric acid, dilute nitric acid or hydrofluoric acid can be used as the acid solution.
Further, when a roughened metal foil is used, minute irregularities are transferred to the surface (contact surface) of the sheet layer. Therefore, when the other base material is adhered to the surface of the sheet layer, the adhesiveness with the other base material becomes better.

In this method, the two obtained sheets are further arranged so as to face each other so that the sheet layers are in contact with each other, and thermocompression bonding is performed to integrate the two sheet layers to form a pressure bonding sheet layer. A sheet having a layer and an adhesive resin layer provided directly on both sides of the pressure bonding sheet layer may be obtained. Since the pressure-bonded sheet layer in such a sheet contains the melt-fired product of F polymer densely, the flexibility and thermal conductivity of the sheet are likely to be further improved.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.
1. 1. Preparation of each component [Particles]
Particle 1: From polymer 1 (melting temperature: 300 ° C.) containing 97.9 mol%, 0.1 mol%, 2.0 mol% of TFE unit, NAH unit and PPVE unit in this order and having an oxygen-containing polar group. Particles (D50: 2.1 μm)
Particle 2: Particles (D50: 1.8 μm) made of a polymer having no oxygen-containing polar group (melting temperature 305 ° C.) consisting of TFE units and PPVE units.
Particle 3: Particles made of polymer 1 (D50: 25 μm)

[Thermal conductive filler]
Filler 1: Spherical filler made of aluminum oxide (D50: 3 μm)
Filler 2: Scale-like filler made of boron nitride (D50: 7 μm)
[Nonionic surfactant]
Surfactant 1: CH ₂ = C (CH ₃ ) C (O) OCH ₂ CH ₂ (CF ₂ ) ₆ F and CH ₂ = C (CH ₃ ) C (O) (OCH ₂ CH ₂ ) ₂₃ OH Copolymer [Adhesive resin composition]
Adhesive resin composition 1: Additive reaction type silicone compound (manufactured by Toray Dow Corning Co., Ltd., "SD4585PSA") and a platinum-based curing catalyst (manufactured by Toray Dow Corning Co., Ltd., "SRX212") [Liquid dispersion medium]
NMP: N-methyl-2-pyrrolidone

2. 2. Preparation of polymer composition (Example 1)
First, the particles 1, the surfactant 1 and the NMP were put into the pot, and the zirconia balls were put into the pot. Then, the pot was rolled at 150 rpm for 1 hour to prepare a composition. Filler 1, surfactant 1 and NMP were put into another pot, and zirconia balls were put into the pot. Then, the pot was rolled at 150 rpm for 1 hour to prepare a composition.
In still another pot, both compositions were charged and zirconia balls were charged. Then, the pot is rolled at 150 rpm for 1 hour to contain a liquid polymer containing particles 1 (20 parts by mass), filler 1 (20 parts by mass), surfactant 1 (4 parts by mass) and NMP (56 parts by mass). Composition 1 was obtained.

(Examples 2 to 4)
Liquid polymer compositions 2 to 4 were obtained in the same manner as in Example 1 except that the types and amounts of the particles and the heat conductive filler were changed as shown in Table 1 below.

(Example 5)
A mixture of 70 parts by mass of particles 3 and 30 parts by mass of filler 2 was prepared.
Next, a powder processing device (hybridization system) that applies stress by sandwiching particles between the inner wall of the container and the agitator while stirring the particles with a stirring blade that rotates at high speed in a cylindrical container. Was charged with the mixture. After that, the particles 3 and the filler 2 are made to collide while floating in an atmosphere of high temperature turbulence, and stress is applied between them to perform a composite treatment to form the polymer 1 as a core, and the filler 2 is formed on the surface of the core. A spherical composite particle 1 (average particle diameter: 35 μm) having a core-shell structure was obtained. The inside of the apparatus during the treatment was kept at a temperature of 100 ° C. or lower under a nitrogen atmosphere, and the treatment time was set to 15 minutes.
A liquid polymer composition 5 was obtained in the same manner as in Example 1 except that the composite particles 1 were used instead of the filler 1 and the particles 1 and the composite particles 1 were used in the amounts shown in Table 1 below.

3. 3. Production of Thermally Conductive Sheet The polymer composition 1 was applied to the surface of an aluminum foil (thickness: 100 μm) by a gravure reverse method to form a liquid film. Next, the aluminum foil on which the liquid film was formed was passed through a drying oven at 120 ° C. for 5 minutes and dried by heating. Then, it was heated at 340 ° C. for 3 minutes in a far-infrared oven under a nitrogen atmosphere. As a result, the metal-clad laminate 1 in which the base sheet layer (thickness: 100 μm) was formed on the surface of the aluminum foil was manufactured.
The pressure-sensitive adhesive resin composition 1 is applied onto the treated surface of a polyethylene terephthalate (PET) film surface-treated with a silicone-based mold release agent, and then heated at 150 ° C. for 3 minutes to form a pressure-sensitive adhesive resin layer (thickness) on the PET film. S: 2 μm) was formed.

The adhesive resin layer and the base sheet layer of the metal-clad laminate 1 were bonded together and pressure-bonded at 25 ° C. to provide the adhesive resin layer directly on the surface of the base sheet layer. The PET film was removed by peeling and the aluminum foil was removed by wet etching to obtain a sheet having a base sheet layer and an adhesive resin layer. Further, the two sheets are arranged so as to face each other so that the base sheet layers are in contact with each other, and thermocompression bonded at 300 ° C., and the heat conductive sheet 1 has an adhesive resin layer, a base sheet layer, and an adhesive resin layer in this order. Got

Thermally conductive sheets 2 to 5 were obtained in the same manner as in the heat conductive sheet 1 except that the polymer composition 1 was changed to the polymer compositions 2 to 5.

4. Evaluation 4-1. Evaluation of Thermal Conductivity A 10 mm square test piece was cut out from the center of each heat conductive sheet, and the thermal conductivity (W / m · K) in the in-plane direction was measured and evaluated according to the following criteria.
[Evaluation criteria]
◯: 3 W / m ・ K or more Δ: 1 W / m ・ K or more and less than 3 W / m ・ K ×: 1 W / m ・ K or less

4-2. Evaluation of peel strength A rectangular (length: 100 mm, width: 10 mm) test piece was cut out from the center of each heat conductive sheet. Then, the position of 50 mm from one end in the length direction of the test piece is fixed, and the base sheet layer and the adhesive resin layer are peeled off at a tensile speed of 50 mm / min and 90 ° from one end in the length direction to the test piece. rice field. The maximum load at this time was measured as the peel strength (N / cm) and evaluated according to the following criteria.
[Evaluation criteria]
◯: Peeling strength is 5 N / cm or more ×: Peeling strength is less than 5 N / cm

4-3. Evaluation of Foldability A square test piece of 5 mm square test piece was cut out from the center of each heat conductive sheet. Then, it was bent 180 ° under the condition of radius of curvature (300 μm), and after applying a load (50 mN, 1 minute) from above, the bending was returned, and the appearance of the test piece was evaluated according to the following criteria.
[Evaluation criteria]
〇: No abnormal appearance was observed in the creases ×: Whitening was observed in the creases The evaluation results of each were summarized in Table 2 below.

The heat conductive sheet of the present invention is excellent in chemical resistance, water repellency, oil repellency, heat resistance, electrical properties, etc., and in particular, is excellent in adhesiveness, thermal conductivity (heat dissipation), electrical properties, and scratch resistance. ..
The heat conductive sheet of the present invention is used in antenna parts, printed wiring boards, aircraft parts, automobile parts, power semiconductor parts, heat exchangers, sports equipment, food industry supplies, saws, packings, gaskets, sliding bearings and the like. It is useful as a coating layer.
In addition, printed wiring boards used for boards for electronic devices such as radars, network routers, backplanes, and wireless infrastructure that require heat dissipation and high-frequency characteristics, boards for various sensors for automobiles, and boards for engine management sensors. In an environment where materials, heat dissipation and antifouling properties are required, the outer layer of heat exchangers (fins, heat transfer tubes, etc.) such as cooling equipment, the surface of vehicle motors, etc. are prone to corrosion deterioration due to high temperatures and oil. It is suitable as a heat dissipation member in an environment where long-term stability is required such as electronic equipment.

Claims (15)

It has a base sheet layer made of a polymer composition containing a heat-meltable tetrafluoroethylene polymer and a heat conductive filler, and an adhesive resin layer directly provided on at least one surface of the base sheet layer. A thermally conductive sheet in which the fluoroethylene-based polymer has an oxygen-containing polar group, or the polymer composition comprises composite particles of the tetrafluoroethylene-based polymer and the thermally conductive filler. The tetrafluoroethylene-based polymer contains units based on perfluoro (alkyl vinyl ether), and contains 1 to 5 mol% of units based on perfluoro (alkyl vinyl ether) with respect to all units, and has a melting temperature of 260 to 320 ° C. The heat conductive sheet according to claim 1, which is a fluoroethylene-based polymer. The heat conductive sheet according to claim 1 or 2, wherein the composite particles are composite particles having the tetrafluoroethylene polymer as a core and having the heat conductive filler on the surface of the core. The heat conductive filler is silicon oxide, aluminum oxide, lead oxide, iron oxide, tin oxide, magnesium oxide, titanium oxide, zinc oxide, antimony pentoxide, zirconium oxide, lanthanum oxide, neodium oxide, cerium oxide, niobium oxide, etc. The heat conductive sheet according to any one of claims 1 to 3, which is a heat conductive filler containing at least one selected from the group consisting of boron nitride and aluminum nitride. The heat conductive sheet according to any one of claims 1 to 4, wherein the heat conductive filler is a heat conductive filler containing aluminum oxide or boron nitride. The heat conductive sheet according to any one of claims 1 to 5, wherein the shape of the heat conductive filler is scaly or spherical. The heat transferable sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive resin layer is made of a silicone composition. Claims 1 to 7 in which the ratio of the content of the heat conductive filler to the total content of the tetrafluoroethylene polymer and the heat conductive filler in the base sheet layer is 0.05 or more. The heat conductive sheet according to any one of the above items. The heat conductive sheet according to any one of claims 1 to 8, wherein the heat conductive sheet has a thickness of 1 to 1000 μm. The heat conductive sheet according to any one of claims 1 to 9, wherein the ratio of the thickness of the adhesive resin layer to the base sheet layer is 0.01 to 5. The heat conductive sheet according to any one of claims 1 to 10, further comprising the adhesive resin layer on both sides of the base sheet layer. A liquid polymer composition containing heat-meltable tetrafluoroethylene polymer particles and a heat-conducting filler and a liquid dispersion medium is applied to a substrate and heated to heat the tetrafluoroethylene-based polymer and the heat-conducting filler. The adhesive resin composition is directly applied to the surface of the sheet layer to form the adhesive resin layer, the base material is removed, and the adhesive resin composition is directly applied to the sheet layer and the surface of the sheet layer. A method for manufacturing a sheet, which obtains a sheet having the provided adhesive resin layer. The production method according to claim 12, wherein the liquid dispersion medium is one kind of liquid dispersion medium selected from the group consisting of amides, ketones and esters. The production method according to claim 12 or 13, wherein the particles of the tetrafluoroethylene polymer have an average particle size of 0.1 to 10 μm. Two sheets having a sheet layer containing a heat-meltable tetrafluoroethylene polymer and the heat conductive filler and an adhesive resin layer directly provided on one side of the sheet layer were prepared, and the two sheets were prepared. The sheet layers are arranged so as to face each other so as to be in contact with each other, and thermocompression-bonded to integrate the two sheet layers to form a pressure-bonding sheet layer, which is directly provided on both sides of the pressure-bonding sheet layer and the pressure-bonding sheet layer. A method for manufacturing a sheet, which obtains a sheet having the pressure-sensitive adhesive resin layer.