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WO2023038052A1 - Heat radiation sheet - Google Patents

Heat radiation sheet Download PDF

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Publication number
WO2023038052A1
WO2023038052A1 PCT/JP2022/033525 JP2022033525W WO2023038052A1 WO 2023038052 A1 WO2023038052 A1 WO 2023038052A1 JP 2022033525 W JP2022033525 W JP 2022033525W WO 2023038052 A1 WO2023038052 A1 WO 2023038052A1
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WO
WIPO (PCT)
Prior art keywords
thermally conductive
conductive filler
average particle
fluororubber
particle size
Prior art date
Application number
PCT/JP2022/033525
Other languages
French (fr)
Japanese (ja)
Inventor
武 水谷
梨夏 高城
Original Assignee
マクセルクレハ株式会社
マクセル株式会社
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Filing date
Publication date
Application filed by マクセルクレハ株式会社, マクセル株式会社 filed Critical マクセルクレハ株式会社
Priority to JP2023546963A priority Critical patent/JPWO2023038052A1/ja
Publication of WO2023038052A1 publication Critical patent/WO2023038052A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/28—Nitrogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon

Definitions

  • the present invention relates to a heat dissipating material sheet used in electronic equipment and the like.
  • heat dissipation material sheets are used in electronic devices.
  • the heat dissipating material sheet is inserted between a heat source such as an electronic component and a heat dissipating member such as a heat sink, and plays a role of efficiently transferring heat generated by the heat source to the heat dissipating member.
  • Composite materials in which a thermally conductive filler is dispersed in a matrix component are generally known as heat dissipating material sheets (see, for example, Patent Document 1).
  • heat dissipating material sheets using silicone rubber as a matrix component are distributed.
  • Patent Document 2 in the volume-based particle size distribution curve of the insulating filler, both large and small particle sizes are used, and the number of particles with a small particle size is larger than that of particles with a large particle size.
  • a heat conductive sheet is described.
  • Patent Document 3 describes a thermally conductive resin molded article containing thermally conductive fillers having different average particle sizes and using fluororubber as the resin.
  • the present invention has been made in view of such circumstances, and an object of the present invention is to provide a heat dissipating material sheet that has heat resistance, flexibility, insulation, and excellent thermal conductivity.
  • the heat dissipating material sheet of the present invention is a heat dissipating material sheet made of a fluororubber composition, wherein the fluororubber composition contains a fluororubber, a softening agent, and a thermally conductive filler, and the content of the thermally conductive filler is 50% by volume or more of the entire fluororubber composition, the thermally conductive filler includes a plurality of thermally conductive fillers having different average particle sizes, and among the plurality of thermally conductive fillers, the average particle size is When a large thermally conductive filler is used as the first thermally conductive filler (F1) and a thermally conductive filler with a small average particle size is used as the second thermally conductive filler (F2), the average of the first thermally conductive filler (F1) The particle diameter is 120 ⁇ m to 500 ⁇ m, the average particle diameter of the second thermally conductive filler (F2) is 10 ⁇ m to 100 ⁇ m, and the first thermal
  • the content of the thermally conductive filler is 65% by volume or less with respect to the entire fluororubber composition.
  • the average particle size of the first thermally conductive filler (F1) is 300 ⁇ m to 500 ⁇ m.
  • the average particle size of the second thermally conductive filler (F2) is 20 ⁇ m to 70 ⁇ m.
  • the heat conductive filler is at least one selected from boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide.
  • the softening agent is characterized by being contained in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the fluororubber.
  • the sheet thickness of the heat dissipating material sheet is 1 mm or more.
  • the heat dissipating material sheet of the present invention contains fluororubber, a softening agent, and thermally conductive fillers (F1, F2), and the content of the thermally conductive filler is 50% by volume or more with respect to the entire fluororubber composition.
  • F1 has an average particle size of 120 ⁇ m to 500 ⁇ m
  • F2 has an average particle size of 10 ⁇ m to 100 ⁇ m
  • the mass ratio (F1:F2) of F1 and F2 in the fluororubber composition is (2:1) to (5 : 1)
  • the entire thermally conductive filler is well filled in the sheet, making it easy to form a thermally conductive path, and as a result, the thermal conductivity can be further improved.
  • the heat dissipating material sheet has heat resistance, flexibility, insulation, and excellent thermal conductivity.
  • the softening agent is contained in 20 to 60 parts by mass with respect to 100 parts by mass of fluororubber, so even if it contains a large amount of heat-conducting filler, it becomes easy to mold and becomes a heat dissipation material sheet with excellent flexibility. In addition, since the adhesiveness to the heat source can be improved, it also contributes to an increase in the heat radiation effect.
  • FIG. 1 is a perspective view showing an example of the heat dissipation material sheet of the present invention.
  • the heat dissipating material sheet 1 is placed between a heat source such as an IC and a heat dissipating member such as a heat sink in an electronic device, for example, and is used with one surface in contact with the heat source and the other surface in contact with the heat dissipating member.
  • the shape of the heat dissipating material sheet 1 is rectangular in plan view, but it can be made into any shape according to the arrangement space, application, and the like.
  • the heat dissipation material sheet 1 is used in a wide range of fields such as electrical parts and automobile parts.
  • the heat dissipation material sheet 1 is made of a fluororubber composition, and the composition contains a fluororubber as a base, a softening agent, and a heat-conducting filler.
  • the heat dissipating material sheet 1 contains a large amount of thermally conductive filler, and the thermally conductive filler is widely dispersed in the sheet, so that thermally conductive paths are easily formed, and excellent thermal conductivity is exhibited. is.
  • the fluororubber composition will be described in detail below.
  • Fluorororubber is a rubber with high heat and chemical resistance.
  • examples of the fluororubber used in the present invention include vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), and the like. may be used alone or in combination of two or more.
  • fluororubber more specifically, vinylidene fluoride/hexafluoropropylene copolymer rubber, tetrafluoroethylene/propylene copolymer rubber, tetrafluoroethylene/hexafluoropropylene copolymer rubber, hexafluoropropylene/ethylene copolymer rubber, Binary copolymer rubber such as polymer rubber, tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer rubber, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer rubber, vinylidene fluoride/tetrafluoropropylene copolymer rubber Ternary copolymer rubber such as fluoroethylene/perfluoromethyl vinyl ether copolymer rubber and tetrafluoroethylene/propylene/vinylidene fluoride copolymer rubber can be used.
  • Binary copolymer rubber such as polymer
  • the fluororubber can be produced by conventional methods such as solution polymerization, suspension polymerization, and emulsion polymerization. A commercially available fluororubber may also be used.
  • the fluorororubber is, for example, solid at room temperature (25° C.).
  • Mooney viscosity (ML 1+10 , 121° C.) of the fluororubber is not particularly limited, it is, for example, 20-60, preferably 20-50.
  • the Mooney viscosity is measured according to JIS K6300.
  • the content of the fluororubber is preferably 20% by mass to 50% by mass, more preferably 20% by mass to 40% by mass, and still more preferably 20% by mass to 35% by mass, relative to the total amount of the fluororubber composition. %.
  • the content of the fluororubber is 20% by mass to 50% by mass, it becomes easy to ensure moldability while imparting good heat resistance, chemical resistance, etc. to the heat dissipation material sheet.
  • Softening agents used in the present invention include petroleum softening agents such as naphthenic oils and paraffin oils, vegetable oil softening agents such as palm oil and castor oil, plasticizers, and liquid rubbers. These may be used alone or in combination of two or more.
  • plasticizers include fluorosilicone oils, phthalates, aliphatic carboxylic acid esters, polyester polymer plasticizers, higher fatty acids such as palmitic acid and stearic acid, higher aliphatic amides, higher fatty acid esters, and higher fatty acids. and the like.
  • Liquid rubber refers to rubber that exhibits a liquid state at room temperature (25°C), and known liquid rubbers such as diene liquid rubber, olefin liquid rubber, and liquid fluororubber can be used. Among these liquid rubbers, it is preferable to use the liquid fluororubber. Note that the liquid fluororubber does not correspond to the fluororubber used as the base described above.
  • the liquid fluororubber commercially available products such as Daiel (registered trademark) G101 (manufactured by Daikin Industries, Ltd.) and Viton (registered trademark) LM (manufactured by Chemours Co., Ltd.) can be used.
  • the above liquid fluororubber is a non-crosslinked rubber component.
  • the viscosity of the liquid fluororubber is not particularly limited, it preferably has a viscosity of 500 cP to 30000 cP at 105° C. from the viewpoint of kneadability and moldability.
  • liquid fluororubber As the softener, it is preferable to use liquid fluororubber as the softener.
  • the liquid fluororubber has the same level of heat resistance and chemical resistance as the fluororubber used as the base, and can suppress bleeding. can be improved.
  • the softening agent is preferably contained in an amount of 10 to 70 parts by mass with respect to 100 parts by mass of the fluororubber. If the content of the softening agent is less than 10 parts by mass, it is difficult to obtain the effect of lowering the rubber hardness, and if the content of the softening agent exceeds 70 parts by mass, the mechanical strength of the sheet may be impaired.
  • the softener is more preferably contained in an amount of 20 to 60 parts by mass, and may be contained in an amount of 40 to 60 parts by mass, based on 100 parts by mass of the fluororubber.
  • thermally conductive filler examples include metal oxides such as aluminum oxide, magnesium oxide and titanium oxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; and nitrogen compounds such as boron nitride and aluminum nitride. , quartz powder, silicon nitride, and silicon compounds such as silicon carbide.
  • thermally conductive fillers may be used alone or in combination of two or more. Among them, it is preferable to use at least one selected from boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide, and it is particularly preferable to use boron nitride, which has excellent thermal conductivity.
  • the shape of the heat-conducting filler particles is not particularly limited, and any of scaly, granular, spherical, columnar, and the like can be used.
  • the thermally conductive filler particles are not limited to primary particles, and granules obtained by agglomerating primary particles, agglomerates thereof, and the like can be used.
  • the shape of the thermally conductive filler particles is scaly, it is difficult to form a thermal conduction path in the thickness direction of the sheet.
  • scale-like boron nitride particles have anisotropy in thermal conductivity, so it is preferable to use granules or aggregates obtained by granulating scale-like primary particles.
  • the boron nitride particles are less likely to be oriented in one direction when the sheet is formed, so that the thermal conductivity can be improved.
  • a plurality of thermally conductive filler particles having different average particle sizes are used as the thermally conductive filler.
  • the plurality of thermally conductive filler particles may have the same or different filler components.
  • a thermally conductive filler having a large average particle size is used as the first thermally conductive filler (F1)
  • a thermally conductive filler having a small average particle size is used as the second thermally conductive filler.
  • a filler (F2) mutual relationships and the like are defined. It is explained below.
  • the average particle size of F1 is, for example, 120 ⁇ m to 500 ⁇ m, preferably 200 ⁇ m to 500 ⁇ m, more preferably 300 ⁇ m to 500 ⁇ m.
  • the average particle size of F2 is, for example, 10 ⁇ m to 100 ⁇ m, preferably 20 ⁇ m to 70 ⁇ m. In addition, it may be 50 ⁇ m to 100 ⁇ m.
  • the ratio of the average particle sizes of F1 and F2 (F1:F2) is, for example, (2:1) to (5:1), preferably (2:1) to (4:1), and more It is preferably (3:1) to (4:1).
  • the average particle size of F1 is less than 120 ⁇ m, the amount of powder increases, resulting in a sheet that is likely to crack and molding (for example, press vulcanization molding) may become difficult.
  • the average particle size of F1 is larger than 500 ⁇ m, the number of particles having a large particle size increases, making it difficult to form a heat conduction path, which may result in poor thermal conductivity.
  • the average particle size of F2 is less than 10 ⁇ m, the bulk becomes large, which may make processing difficult due to fragility and cracking. Moreover, it becomes difficult to form a heat conduction path, and there is a possibility that the heat conductivity is deteriorated.
  • the average particle size of F2 is larger than 100 ⁇ m, the average particle size of F2 is too close to that of F1, so that the thermally conductive filler is difficult to be densely packed. may be inferior.
  • the average particle size of F1 and F2 is the particle size (D50) at the point where the volume-based cumulative value is 50% when the particle size distribution is a cumulative distribution, and is a laser diffraction/scattering particle size. It can be measured by a wet method using a distribution measuring device (eg LA-920 manufactured by Horiba Ltd.).
  • a distribution measuring device eg LA-920 manufactured by Horiba Ltd.
  • a magnifying glass capable of appropriately observing the cross section of the sheet can be used for actual measurement.
  • the mass ratio (F1:F2) of F1 and F2 in the fluororubber composition is (2:1) to (5:1), preferably (2:1) to (4:1), More preferably (3:1) to (4:1).
  • the mass of F2 is 1, if the mass of F1 is less than 2 (when the amount of F1 is too small), the number of particles with a small average particle size increases, making it difficult to form a heat conduction path, resulting in poor thermal conductivity. may decrease.
  • the mass of F1 is greater than 5 (when the amount of F1 is too large), the number of particles with a small average particle size decreases, so the number of particles that enter the gap between particles with a large average particle size decreases, resulting in a heat conduction path becomes difficult to form, and there is a risk that the thermal conductivity will decrease.
  • the plurality of thermally conductive fillers are not limited to two types (F1, F2), and may further include thermally conductive fillers with different average particle sizes. In this case, it is preferable that at least two types of particles having a size relationship among the plurality of thermally conductive fillers satisfy the above relationship.
  • the content of the thermally conductive filler (the total amount thereof when using a plurality of thermally conductive fillers having different average particle sizes) is 50% by volume or more relative to the entire fluororubber composition, preferably It is more than 50% by volume, more preferably 52% by volume or more, and particularly preferably 55% by volume or more. This makes it easier to form a heat conduction path in the sheet, thereby exhibiting excellent heat conductivity.
  • % or less may be 70 volume % or less, or may be 65 volume % or less.
  • the heat dissipating material sheet of the present invention has insulating properties, and preferably has a dielectric breakdown voltage of 4.50 kV or higher or a dielectric breakdown strength of 3.50 kV/mm or higher as defined in JIS C 2110-1. .
  • the fluororubber composition preferably does not contain a conductive filler.
  • conductive fillers include solid carbon materials such as graphite powder, conductive carbon black, carbon nanotubes, and fullerene; metal powders such as copper powder, silver powder, and iron powder; and conductive materials such as conductive tin oxide and conductive titanium oxide. metal oxides and the like.
  • the above-mentioned fluororubber is preferably crosslinked.
  • a cross-linking method for example, chemical cross-linking such as press vulcanization can be performed.
  • Vulcanizing agents used for press vulcanization include dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,3-bis-(t-butylperoxy-isopropyl) Organic peroxides such as benzene, t-butylcumyl peroxide, di-t-butylperoxide can be used.
  • the content of the vulcanizing agent is preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the fluororubber.
  • the cross-linking method is not limited to press vulcanization, and a normal cross-linking method can be employed, for example, a radiation cross-linking method may be performed. Electron beams, ⁇ -rays, X-rays, and the like are used in radiation crosslinking.
  • fluororubber softening agent, heat conductive filler, and vulcanizing agent
  • other additives can be added to the fluororubber composition as long as they do not impair the effects of the present invention.
  • anti-aging agents e.g., anti-aging agents, vulcanization accelerators, reinforcing agents, coloring agents and the like can be blended.
  • the heat dissipation material sheet of the present invention has excellent thermal conductivity, and the thermal conductivity is preferably 3.0 W/mK or higher, more preferably 4.5 W/mK or higher, and more preferably 5.0 W/mK or higher. .
  • the thermal conductivity is 20 W/mK or less, and may be 15 W/mK or less.
  • the thermal conductivity of the heat dissipating material sheet is the value measured by the hot wire method. For example, it can be obtained by measuring a test piece with a thickness of 1 mm with a thermal conductivity meter.
  • the hardness of the heat dissipating material sheet of the present invention is not particularly limited, it preferably has a hardness of 20 to 60, more preferably 20 to 50, according to the type D durometer specified in JIS K6253. As a result, good flexibility can be imparted, and complicated shapes such as narrow spaces and curved surfaces can be fitted, making it applicable to a wide range of applications.
  • the heat dissipation material sheet can be produced by (1) preparing a raw material composition, and (2) molding and crosslinking the prepared raw material composition.
  • the raw material composition of (1) is prepared, for example, by kneading various raw materials such as fluororubber, softening agent, and heat-conductive filler with two rolls.
  • the heat dissipating material sheet of the present invention contains a large amount of thermally conductive filler, the kneading operation tends to be relatively difficult. Therefore, in the present invention, it is preferable to manufacture by drying, molding and vulcanizing after preparing a solution containing various raw materials.
  • a heat conductive filler and a softening agent are placed in a container, a solvent is added and mixed and dispersed, and then a compound containing fluororubber that has been kneaded in advance by a kneading roll is placed in the container and dissolved. .
  • the thermal conductive filler to the base fluororesin is added. It is thought that dispersibility can be improved.
  • a predetermined amount of the obtained solution is poured into the mold to volatilize the solvent. After that, the dried product is vulcanized by pressing to obtain a heat dissipating material sheet.
  • the obtained heat dissipation material sheet may be annealed as necessary.
  • extrusion molding As a molding method, extrusion molding, injection molding, transfer molding, and the like can be performed, but press molding is preferable, and the heat radiation material sheet is preferably a press-molded body.
  • the sheet thickness of the heat radiation material sheet is not particularly limited, and is, for example, 0.5 mm or more, preferably 1 mm or more.
  • the sheet thickness is preferably thin from the viewpoint of installation in a narrow space and flexibility of shape, and the sheet thickness is, for example, 5 mm or less, and may be 3 mm or less.
  • Examples 1-6, Comparative Examples 1-5 The composition of the fluororubber composition of each test example is as shown in Tables 1 and 2.
  • a liquid fluororubber was used as a softening agent.
  • the heat conductive filler three types of boron nitride A to C with different average particle sizes and three types of aluminum oxide (alumina) A to C with different average particle sizes are used, and one or two of these are used. were combined, and the one with a larger average particle size was designated as F1, and the one with a smaller average particle size was designated as F2.
  • the boron nitride particles granules obtained by granulating scale-like primary particles or aggregates thereof were used.
  • "Volume % of thermally conductive filler (F1+F2)" in Tables 1 and 2 indicates the volume % of the entire thermally conductive filler with respect to the entire fluororubber composition.
  • each heat conductive filler has a average particle size of 300 ⁇ m to 500 ⁇ m Boron nitride B: 55 ⁇ m to 65 ⁇ m Boron nitride C: 25 ⁇ m Alumina A: 600 ⁇ m Alumina B: 355 ⁇ m Alumina C: 53 ⁇ m
  • test sheet was produced by the following procedure. 1. A compound was obtained by previously kneading the fluororubber, the vulcanizing agent, and the like with a kneading roll. 2. Boron nitride or alumina, liquid fluororubber, etc. were weighed in a container, methyl ethyl ketone (MEK) was added, mixed and dispersed, and then the above compound was placed in a container and dissolved. 3. A predetermined amount of the resulting solution was poured into a mold, subjected to a vacuum defoaming treatment, and then dried until the solvent was volatilized. 4. After the dried sheet was vulcanized by pressing, it was annealed to obtain a test sheet.
  • MEK methyl ethyl ketone
  • thermal conductivity tensile strength, elongation at break, and hardness (type D) were measured as physical property evaluations in the normal state.
  • the thermal conductivity was measured at 23° C. according to the hot wire method specified in JIS R2616 after cutting out a sample of dimensions (50 mm ⁇ 100 mm ⁇ 1 mm) from each test sheet.
  • Tensile strength and elongation at break were measured according to the test method specified in JIS K6251.
  • the hardness was measured according to the test method specified in JIS K6253 (type D durometer).
  • Example 2 when the test sheet of Example 2 was measured according to the test method specified in JIS C 2110-1, the dielectric breakdown voltage was 4.99 kV and the dielectric breakdown strength was 3.84 kV/mm. there were.
  • boron nitride and liquid fluororubber are dispersed in advance in the solvent, and it is possible that the use of a large amount of liquid fluororubber has improved the dispersibility of the thermally conductive filler in the sheet. be done.
  • Comparative Example 2 Even when two types of boron nitride particles having an average particle size are combined, when those having a relatively small average particle size are combined (Comparative Example 2), cracking occurs during vulcanization press, could not be molded. That is, the result was that the bulk increased and the workability decreased. For Comparative Example 2, various physical properties could not be evaluated.
  • boron nitride was used as the thermally conductive filler than when alumina was used.
  • the specific gravity of alumina is higher than that of boron nitride (for example, boron nitride is 2.15 g/cm 3 and alumina is 3.98 g/cm 3 ). It is considered that the uneven distribution of alumina led to the decrease in thermal conductivity. Further, when alumina is used, boron nitride is more preferable in terms of post-workability because it is difficult to cut the sheet.
  • Examples 1 to 3 and 5 maintain their thermal conductivity without deterioration even when placed in a high temperature environment for a long period of time.
  • the thermal conductivity was well maintained, and high-temperature deterioration was prevented.
  • the heat dissipating material sheet of the present invention has heat resistance, flexibility, insulation, and excellent thermal conductivity, so it is used in electronic devices and the like, and can quickly transmit heat generated by a heat source. .

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Abstract

Provided is a heat radiation sheet having heat resistance, flexibility, and insulating properties and further having excellent thermal conductivity. The heat radiation sheet 1 comprises a fluororubber composition, wherein the fluororubber composition comprises a fluororubber, a softener, and a thermally conductive filler, the content of the thermally conductive filler being 50 vol% or higher with respect to the whole fluororubber composition and the thermally conductive filler being at least one compound selected from among boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide.

Description

放熱材シートHeat dissipation material sheet
　本発明は、電子機器などにおいて利用される放熱材シートに関する。 The present invention relates to a heat dissipating material sheet used in electronic equipment and the like.
　近年、パソコン、携帯電話などの電子機器の小型化および高性能化が進んでいる。電子機器の高性能化に伴い、ＩＣやパワー部品、ＬＥＤなどから発生する発熱量も著しく増加している。加えて、小型化の進展により、電子機器内の空間が狭くなり、対流による冷却効果などが得られにくくなっている。そのため、電子機器などにおいて発生する熱への対処は重要な課題となっている。 In recent years, electronic devices such as personal computers and mobile phones have become smaller and more sophisticated. As the performance of electronic equipment has improved, the amount of heat generated from ICs, power parts, LEDs, and the like has also increased remarkably. In addition, due to the progress of miniaturization, the space inside the electronic device has become narrower, making it difficult to obtain a cooling effect due to convection. Therefore, how to deal with heat generated in electronic devices and the like has become an important issue.
　例えば、この対処として、電子機器などでは放熱材シートが用いられている。放熱材シートは、電子部品などの熱源とヒートシンクなどの放熱部材との間に挿入され、熱源で発生した熱を効率よく放熱部材に伝達する役割を担っている。一般に、放熱材シートとしては、マトリックス成分中に熱伝導フィラーを分散させた複合材料が知られている（例えば特許文献１参照）。市場では、例えばマトリックス成分にシリコーンゴムを用いた放熱材シートなどが流通している。 For example, as a countermeasure, heat dissipation material sheets are used in electronic devices. The heat dissipating material sheet is inserted between a heat source such as an electronic component and a heat dissipating member such as a heat sink, and plays a role of efficiently transferring heat generated by the heat source to the heat dissipating member. Composite materials in which a thermally conductive filler is dispersed in a matrix component are generally known as heat dissipating material sheets (see, for example, Patent Document 1). In the market, for example, heat dissipating material sheets using silicone rubber as a matrix component are distributed.
　特許文献２では、絶縁フィラーの体積基準の粒度分布曲線において、粒子径が大きいものと小さいものとを併用し、粒子径が小さい粒子の方が粒子径が大きい粒子よりも多い熱伝導シートが記載されている。また、特許文献３では、平均粒子径が異なる熱伝導性フィラーを含み、樹脂にフッ素ゴムを用いた熱伝導性樹脂成形品が記載されている。 In Patent Document 2, in the volume-based particle size distribution curve of the insulating filler, both large and small particle sizes are used, and the number of particles with a small particle size is larger than that of particles with a large particle size. A heat conductive sheet is described. It is Further, Patent Document 3 describes a thermally conductive resin molded article containing thermally conductive fillers having different average particle sizes and using fluororubber as the resin.
国際公開第２０１８／１８０９９７号WO2018/180997 特開２０１９－１０８４９６号公報JP 2019-108496 A 国際公開第２０１７／１３５２３７号WO2017/135237
　特許文献２のように、粒子径が小さい粒子の方が粒子径が大きい粒子よりも多い熱伝導シートの場合、嵩が大きくなるため加工が難しくなりやすい。また、熱伝導パスが形成しにくくなるため、熱伝導性が劣る可能性がある。また、特許文献３では、平均粒子径が異なる熱伝導性フィラーは、いずれも平均粒子径が数十μｍ程度以下のものであり、粒子径が小さく高い熱伝導性を得ることが難しく、また成形しにくいことも考えられる。 As in Patent Document 2, in the case of a heat conductive sheet with more particles with a smaller particle size than particles with a larger particle size, processing tends to be difficult due to increased bulk. Moreover, since it becomes difficult to form a heat conduction path, there is a possibility that the heat conductivity is deteriorated. In addition, in Patent Document 3, the thermally conductive fillers with different average particle sizes are all about several tens of μm or less in average particle size, and it is difficult to obtain high thermal conductivity due to the small particle size. It may also be difficult.
　ところで、電子機器の更なる高性能化などにより、放熱材シートの熱伝導性への要求はますます高まっている。また、放熱効果を高めるために、放熱材シートを熱源により密着させることから、シートの柔軟性や高耐熱性なども重要になってくる。 By the way, due to the further improvement of the performance of electronic devices, the demand for thermal conductivity of heat dissipating material sheets is increasing. In addition, since the heat dissipation material sheet is brought into close contact with the heat source in order to enhance the heat dissipation effect, the flexibility and high heat resistance of the sheet are also important.
　本発明は、このような事情に鑑みてなされたものであり、耐熱性、柔軟性、および絶縁性を有するとともに、優れた熱伝導性を有する放熱材シートを提供することを目的とする。 The present invention has been made in view of such circumstances, and an object of the present invention is to provide a heat dissipating material sheet that has heat resistance, flexibility, insulation, and excellent thermal conductivity.
　本発明の放熱材シートは、フッ素ゴム組成物からなる放熱材シートであって、上記フッ素ゴム組成物は、フッ素ゴムと、軟化剤と、熱伝導フィラーとを含み、上記熱伝導フィラーの含有量は、上記フッ素ゴム組成物全体に対して５０体積％以上であり、上記熱伝導フィラーは、平均粒子径が異なる複数の熱伝導フィラーを含み、上記複数の熱伝導フィラーのうち、平均粒子径が大きい熱伝導フィラーを第１の熱伝導フィラー（Ｆ１）とし、平均粒子径が小さい熱伝導フィラーを第２の熱伝導フィラー（Ｆ２）とした場合、上記第１の熱伝導フィラー（Ｆ１）の平均粒子径は１２０μｍ～５００μｍであり、上記第２の熱伝導フィラー（Ｆ２）の平均粒子径は１０μｍ～１００μｍであり、上記フッ素ゴム組成物における上記第１の熱伝導フィラー（Ｆ１）と上記第２の熱伝導フィラー（Ｆ２）の質量比（Ｆ１：Ｆ２）は（２：１）～（５：１）であることを特徴とする。 The heat dissipating material sheet of the present invention is a heat dissipating material sheet made of a fluororubber composition, wherein the fluororubber composition contains a fluororubber, a softening agent, and a thermally conductive filler, and the content of the thermally conductive filler is 50% by volume or more of the entire fluororubber composition, the thermally conductive filler includes a plurality of thermally conductive fillers having different average particle sizes, and among the plurality of thermally conductive fillers, the average particle size is When a large thermally conductive filler is used as the first thermally conductive filler (F1) and a thermally conductive filler with a small average particle size is used as the second thermally conductive filler (F2), the average of the first thermally conductive filler (F1) The particle diameter is 120 μm to 500 μm, the average particle diameter of the second thermally conductive filler (F2) is 10 μm to 100 μm, and the first thermally conductive filler (F1) and the second thermally conductive filler (F1) in the fluororubber composition The mass ratio (F1:F2) of the thermal conductive filler (F2) is (2:1) to (5:1).
　上記熱伝導フィラーの含有量は、上記フッ素ゴム組成物全体に対して６５体積％以下であることを特徴とする。 The content of the thermally conductive filler is 65% by volume or less with respect to the entire fluororubber composition.
　上記第１の熱伝導フィラー（Ｆ１）の平均粒子径は３００μｍ～５００μｍであることを特徴とする。 The average particle size of the first thermally conductive filler (F1) is 300 μm to 500 μm.
　上記第２の熱伝導フィラー（Ｆ２）の平均粒子径は２０μｍ～７０μｍであることを特徴とする。 The average particle size of the second thermally conductive filler (F2) is 20 μm to 70 μm.
　上記熱伝導フィラーが窒化ホウ素、窒化アルミニウム、酸化アルミニウム、および酸化マグネシウムから選択される少なくとも１種であることを特徴とする。 The heat conductive filler is at least one selected from boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide.
　上記軟化剤は、上記フッ素ゴム１００質量部に対して２０質量部～６０質量部含まれることを特徴とする。 The softening agent is characterized by being contained in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the fluororubber.
　上記放熱材シートのシート厚さが１ｍｍ以上であることを特徴とする。 It is characterized in that the sheet thickness of the heat dissipating material sheet is 1 mm or more.
　本発明の放熱材シートは、フッ素ゴムと、軟化剤と、熱伝導フィラー（Ｆ１、Ｆ２）とを含み、熱伝導フィラーの含有量は、フッ素ゴム組成物全体に対して５０体積％以上であり、Ｆ１の平均粒子径は１２０μｍ～５００μｍであり、Ｆ２の平均粒子径は１０μｍ～１００μｍであり、フッ素ゴム組成物におけるＦ１とＦ２の質量比（Ｆ１：Ｆ２）は（２：１）～（５：１）であるので、シート中に熱伝導フィラー全体が良好に充填され、熱伝導パスを形成しやすくなり、その結果、熱伝導性をより向上させることができる。これにより、耐熱性、柔軟性、および絶縁性を有するとともに、優れた熱伝導性を有する放熱材シートになる。 The heat dissipating material sheet of the present invention contains fluororubber, a softening agent, and thermally conductive fillers (F1, F2), and the content of the thermally conductive filler is 50% by volume or more with respect to the entire fluororubber composition. , F1 has an average particle size of 120 μm to 500 μm, F2 has an average particle size of 10 μm to 100 μm, and the mass ratio (F1:F2) of F1 and F2 in the fluororubber composition is (2:1) to (5 : 1), the entire thermally conductive filler is well filled in the sheet, making it easy to form a thermally conductive path, and as a result, the thermal conductivity can be further improved. As a result, the heat dissipating material sheet has heat resistance, flexibility, insulation, and excellent thermal conductivity.
　軟化剤はフッ素ゴム１００質量部に対して２０質量部～６０質量部含まれるので、熱伝導フィラーを多量に含んでいても、成形しやすくなり、柔軟性に優れる放熱材シートになる。また、熱源との密着性を向上できることから、放熱効果の増大にも寄与する。 The softening agent is contained in 20 to 60 parts by mass with respect to 100 parts by mass of fluororubber, so even if it contains a large amount of heat-conducting filler, it becomes easy to mold and becomes a heat dissipation material sheet with excellent flexibility. In addition, since the adhesiveness to the heat source can be improved, it also contributes to an increase in the heat radiation effect.
本発明の放熱材シートの一例を示す斜視図である。It is a perspective view which shows an example of the thermal radiation material sheet|seat of this invention.
　図１は、本発明の放熱材シートの一例を示す斜視図である。放熱材シート１は、例えば電子機器においてＩＣなどの熱源とヒートシンクなどの放熱部材との間に配置され、一方の面を熱源に接触させ、他方の面を放熱部材に接触させて使用される。なお、図１では、放熱材シート１の形状を平面視矩形状としているが、配置スペースや用途などに応じて任意の形状にすることができる。放熱材シート１は、電気部品、自動車部品などの広範な分野で使用される。 FIG. 1 is a perspective view showing an example of the heat dissipation material sheet of the present invention. The heat dissipating material sheet 1 is placed between a heat source such as an IC and a heat dissipating member such as a heat sink in an electronic device, for example, and is used with one surface in contact with the heat source and the other surface in contact with the heat dissipating member. In FIG. 1, the shape of the heat dissipating material sheet 1 is rectangular in plan view, but it can be made into any shape according to the arrangement space, application, and the like. The heat dissipation material sheet 1 is used in a wide range of fields such as electrical parts and automobile parts.
　放熱材シート１はフッ素ゴム組成物からなり、該組成物は、ベースとなるフッ素ゴムと、軟化剤と、熱伝導フィラーとを含む。特に、放熱材シート１は、多量の熱伝導フィラーを含んでおり、該熱伝導フィラーがシート中に広く分散していることから熱伝導パスが形成されやすく、優れた熱伝導性を発揮するものである。以下に、フッ素ゴム組成物について詳細に説明する。 The heat dissipation material sheet 1 is made of a fluororubber composition, and the composition contains a fluororubber as a base, a softening agent, and a heat-conducting filler. In particular, the heat dissipating material sheet 1 contains a large amount of thermally conductive filler, and the thermally conductive filler is widely dispersed in the sheet, so that thermally conductive paths are easily formed, and excellent thermal conductivity is exhibited. is. The fluororubber composition will be described in detail below.
＜フッ素ゴム＞
　フッ素ゴムは、高度な耐熱性および耐薬品性を有するゴムである。本発明に用いるフッ素ゴムとしては、例えば、フッ化ビニリデン系ゴム（ＦＫＭ）、テトラフルオロエチレン－プロピレンゴム（ＦＥＰＭ）、テトラフルオロエチレン－パーフルオロメチルビニルエーテルゴム（ＦＦＫＭ）などが挙げられ、これらフッ素ゴムは単独で用いてもよく、２種以上を組み合わせて用いてもよい。 <Fluoro rubber>
Fluororubber is a rubber with high heat and chemical resistance. Examples of the fluororubber used in the present invention include vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), and the like. may be used alone or in combination of two or more.
　フッ素ゴムとして、より具体的には、フッ化ビニリデン／ヘキサフルオロプロピレン共重合体ゴム、テトラフルオロエチレン／プロピレン共重合体ゴム、テトラフルオロエチレン／ヘキサフルオロプロピレン共重合体ゴム、ヘキサフルオロプロピレン／エチレン共重合体ゴム、テトラフルオロエチレン／パーフルオロ（アルキルビニルエーテル）共重合体ゴムなどの二元系共重合体ゴムや、フッ化ビニリデン／テトラフルオロエチレン／ヘキサフルオロプロピレン共重合体ゴム、フッ化ビニリデン／テトラフルオロエチレン／パーフロロメチルビニルエーテル共重合体ゴム、テトラフルオロエチレン／プロピレン／フッ化ビニリデン共重合体ゴムなどの三元系共重合体ゴムなどを用いることができる。 As the fluororubber, more specifically, vinylidene fluoride/hexafluoropropylene copolymer rubber, tetrafluoroethylene/propylene copolymer rubber, tetrafluoroethylene/hexafluoropropylene copolymer rubber, hexafluoropropylene/ethylene copolymer rubber, Binary copolymer rubber such as polymer rubber, tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer rubber, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer rubber, vinylidene fluoride/tetrafluoropropylene copolymer rubber Ternary copolymer rubber such as fluoroethylene/perfluoromethyl vinyl ether copolymer rubber and tetrafluoroethylene/propylene/vinylidene fluoride copolymer rubber can be used.
　上記フッ素ゴムは、溶液重合、懸濁重合、乳化重合などの常法により製造することができる。また、市販されているフッ素ゴムを用いてもよい。 The fluororubber can be produced by conventional methods such as solution polymerization, suspension polymerization, and emulsion polymerization. A commercially available fluororubber may also be used.
　上記フッ素ゴムは、例えば常温（２５℃）で固体状を呈する。フッ素ゴムのムーニー粘度（ＭＬ１＋１０、１２１℃）は特に限定されないが、例えば２０～６０であり、好ましくは２０～５０である。上記ムーニー粘度はＪＩＳ　Ｋ６３００に準拠して測定される。 The fluororubber is, for example, solid at room temperature (25° C.). Although the Mooney viscosity (ML 1+10 , 121° C.) of the fluororubber is not particularly limited, it is, for example, 20-60, preferably 20-50. The Mooney viscosity is measured according to JIS K6300.
　フッ素ゴムの含有量は、フッ素ゴム組成物全量に対して、好ましくは２０質量％～５０質量％であり、より好ましくは２０質量％～４０質量％であり、さらに好ましくは２０質量％～３５質量％である。フッ素ゴムの含有量が２０質量％～５０質量％であると、放熱材シートに耐熱性、耐薬品性などを良好に付与しつつ、成形性を確保しやすくなる。 The content of the fluororubber is preferably 20% by mass to 50% by mass, more preferably 20% by mass to 40% by mass, and still more preferably 20% by mass to 35% by mass, relative to the total amount of the fluororubber composition. %. When the content of the fluororubber is 20% by mass to 50% by mass, it becomes easy to ensure moldability while imparting good heat resistance, chemical resistance, etc. to the heat dissipation material sheet.
＜軟化剤＞
　本発明に用いる軟化剤としては、例えば、ナフテン系オイル、パラフィン系オイルなどの石油系軟化剤、パーム油、ひまし油などの植物油系軟化剤、可塑剤、液状ゴムなどが用いられる。これらは単独で用いてもよく、２種以上を組み合わせて用いてもよい。 <Softener>
Examples of softening agents used in the present invention include petroleum softening agents such as naphthenic oils and paraffin oils, vegetable oil softening agents such as palm oil and castor oil, plasticizers, and liquid rubbers. These may be used alone or in combination of two or more.
　可塑剤としては、例えば、フッ化シリコーンオイル、フタル酸エステル、脂肪族カルボン酸エステル、ポリエステル系高分子可塑剤、パルミチン酸、ステアリン酸などの高級脂肪酸、高級脂肪族アミド、高級脂肪酸エステル、高級脂肪酸の金属塩などが挙げられる。 Examples of plasticizers include fluorosilicone oils, phthalates, aliphatic carboxylic acid esters, polyester polymer plasticizers, higher fatty acids such as palmitic acid and stearic acid, higher aliphatic amides, higher fatty acid esters, and higher fatty acids. and the like.
　液状ゴムは、常温（２５℃）において液状を呈するゴムをいい、ジエン系液状ゴム、オレフィン系液状ゴム、液状フッ素ゴムなどの周知の液状ゴムを用いることができる。これら液状ゴムの中でも、液状フッ素ゴムを用いることが好ましい。なお、液状フッ素ゴムは、上述したベースとして用いるフッ素ゴムに該当しないものとする。液状フッ素ゴムとしては、市販されているダイエル（登録商標）Ｇ１０１（ダイキン工業株式会社製）、バイトン（登録商標）ＬＭ（ケマーズ株式会社製）などを用いることができる。 Liquid rubber refers to rubber that exhibits a liquid state at room temperature (25°C), and known liquid rubbers such as diene liquid rubber, olefin liquid rubber, and liquid fluororubber can be used. Among these liquid rubbers, it is preferable to use the liquid fluororubber. Note that the liquid fluororubber does not correspond to the fluororubber used as the base described above. As the liquid fluororubber, commercially available products such as Daiel (registered trademark) G101 (manufactured by Daikin Industries, Ltd.) and Viton (registered trademark) LM (manufactured by Chemours Co., Ltd.) can be used.
　上記液状フッ素ゴムは、架橋しないゴム成分である。液状フッ素ゴムの粘度は特に限定されないが、混練性や成形性の観点から、１０５℃における粘度が、５００ｃＰ～３００００ｃＰが好ましい。 The above liquid fluororubber is a non-crosslinked rubber component. Although the viscosity of the liquid fluororubber is not particularly limited, it preferably has a viscosity of 500 cP to 30000 cP at 105° C. from the viewpoint of kneadability and moldability.
　本発明において、軟化剤としては液状フッ素ゴムを用いることが好ましい。液状フッ素ゴムは、ベースとして用いるフッ素ゴムと同程度の耐熱性と耐薬品性を有しており、またブリードを抑制でき、常温（２５℃）で固体状のフッ素ゴムの加工性改良や低硬度化を図ることができる。 In the present invention, it is preferable to use liquid fluororubber as the softener. The liquid fluororubber has the same level of heat resistance and chemical resistance as the fluororubber used as the base, and can suppress bleeding. can be improved.
　軟化剤は、フッ素ゴム１００質量部に対して１０質量部～７０質量部含まれることが好ましい。軟化剤の含有量が１０質量部未満となると、ゴム硬度を低下させる作用が得られにくく、軟化剤の含有量が７０質量部を超えると、シートの機械的強度が損なわれるおそれがある。軟化剤は、より好ましくは、フッ素ゴム１００質量部に対して２０質量部～６０質量部含まれ、４０質量部～６０質量部含まれていてもよい。 The softening agent is preferably contained in an amount of 10 to 70 parts by mass with respect to 100 parts by mass of the fluororubber. If the content of the softening agent is less than 10 parts by mass, it is difficult to obtain the effect of lowering the rubber hardness, and if the content of the softening agent exceeds 70 parts by mass, the mechanical strength of the sheet may be impaired. The softener is more preferably contained in an amount of 20 to 60 parts by mass, and may be contained in an amount of 40 to 60 parts by mass, based on 100 parts by mass of the fluororubber.
＜熱伝導フィラー＞
　本発明で用いる熱伝導フィラーとしては、例えば、酸化アルミニウム、酸化マグネシウム、酸化チタンなどの金属酸化物や、水酸化アルミニウム、水酸化マグネシウムなどの金属水酸化物、窒化ホウ素、窒化アルミニウムなどの窒素化合物、石英粉、窒化ケイ素、炭化ケイ素などのケイ素化合物などが挙げられる。これら熱伝導フィラーは単独で用いてもよく、２種以上を組み合わせて用いてもよい。上記の中でも、窒化ホウ素、窒化アルミニウム、酸化アルミニウム、および酸化マグネシウムから選択される少なくとも１種を用いることが好ましく、特に、優れた熱伝導性を有する窒化ホウ素を用いることがより好ましい。 <Heat conductive filler>
Examples of the thermally conductive filler used in the present invention include metal oxides such as aluminum oxide, magnesium oxide and titanium oxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; and nitrogen compounds such as boron nitride and aluminum nitride. , quartz powder, silicon nitride, and silicon compounds such as silicon carbide. These thermally conductive fillers may be used alone or in combination of two or more. Among them, it is preferable to use at least one selected from boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide, and it is particularly preferable to use boron nitride, which has excellent thermal conductivity.
　熱伝導フィラー粒子の形状は特に限定されず、鱗片状、粒状、球状、柱状などのいずれも用いることができる。ここで、熱伝導フィラー粒子としては、一次粒子に限らず、一次粒子を造粒した造粒体、これらが凝集してなる凝集体などを用いることができる。熱伝導フィラー粒子の形状が鱗片状の場合、シートの厚さ方向に熱伝導パスを形成しにくいことから、鱗片状以外の形状が好ましく、粒状、球状、柱状などが好ましい。例えば、窒化ホウ素の場合、鱗片状の窒化ホウ素粒子は熱伝導異方性を有するため、鱗片状の一次粒子を造粒した造粒体や凝集体を用いることが好ましい。造粒体や凝集体を用いることで、シートを形成した際に窒化ホウ素粒子が一方向に配向しにくくなるため、熱伝導性を向上させることができる。 The shape of the heat-conducting filler particles is not particularly limited, and any of scaly, granular, spherical, columnar, and the like can be used. Here, the thermally conductive filler particles are not limited to primary particles, and granules obtained by agglomerating primary particles, agglomerates thereof, and the like can be used. When the shape of the thermally conductive filler particles is scaly, it is difficult to form a thermal conduction path in the thickness direction of the sheet. For example, in the case of boron nitride, scale-like boron nitride particles have anisotropy in thermal conductivity, so it is preferable to use granules or aggregates obtained by granulating scale-like primary particles. By using granules or agglomerates, the boron nitride particles are less likely to be oriented in one direction when the sheet is formed, so that the thermal conductivity can be improved.
　本発明において、熱伝導フィラーとしては、異なる平均粒子径を持つ複数の熱伝導性フィラー粒子を用いている。この場合、複数の熱伝導性フィラー粒子は、フィラー成分が互いに同じでもよく、異なっていてもよい。異なる平均粒子径を持つ複数の熱伝導性フィラー粒子を用いることで、大きい方の熱伝導性フィラー粒子同士の間隙に、小さい方の熱伝導性フィラー粒子が充填されやすくなり、シート中に熱伝導フィラー粒子を良好に充填させることができる。更に、本発明では、複数の熱伝導性フィラー粒子のうち、平均粒子径が大きい熱伝導フィラーを第１の熱伝導フィラー（Ｆ１）とし、平均粒子径が小さい熱伝導フィラーを第２の熱伝導フィラー（Ｆ２）として、相互の関係などを規定している。以下に説明する。 In the present invention, a plurality of thermally conductive filler particles having different average particle sizes are used as the thermally conductive filler. In this case, the plurality of thermally conductive filler particles may have the same or different filler components. By using a plurality of thermally conductive filler particles with different average particle sizes, the gaps between the larger thermally conductive filler particles are easily filled with the smaller thermally conductive filler particles, and heat is conducted in the sheet. Filler particles can be well filled. Furthermore, in the present invention, among the plurality of thermally conductive filler particles, a thermally conductive filler having a large average particle size is used as the first thermally conductive filler (F1), and a thermally conductive filler having a small average particle size is used as the second thermally conductive filler. As a filler (F2), mutual relationships and the like are defined. It is explained below.
　Ｆ１の平均粒子径は、例えば１２０μｍ～５００μｍであり、好ましくは２００μｍ～５００μｍであり、より好ましくは３００μｍ～５００μｍである。Ｆ２の平均粒子径は、例えば１０μｍ～１００μｍであり、好ましくは２０μｍ～７０μｍである。なお、５０μｍ～１００μｍであってもよい。また、Ｆ１とＦ２の平均粒子径の比（Ｆ１：Ｆ２）は、例えば（２：１）～（５：１）であり、好ましくは（２：１）～（４：１）であり、より好ましくは（３：１）～（４：１）である。 The average particle size of F1 is, for example, 120 μm to 500 μm, preferably 200 μm to 500 μm, more preferably 300 μm to 500 μm. The average particle size of F2 is, for example, 10 μm to 100 μm, preferably 20 μm to 70 μm. In addition, it may be 50 μm to 100 μm. In addition, the ratio of the average particle sizes of F1 and F2 (F1:F2) is, for example, (2:1) to (5:1), preferably (2:1) to (4:1), and more It is preferably (3:1) to (4:1).
　Ｆ１の平均粒子径が１２０μｍよりも小さいと、粉体の量が多くなる結果、シートが割れやすくなり、また成形（例えばプレス加硫成形）が難しくなるおそれがある。一方、Ｆ１の平均粒子径が５００μｍより大きいと、粒子径が大きい粒子が多くなることで熱伝導パスが形成されにくくなり、熱伝導性が劣るおそれがある。また、Ｆ２の平均粒子径が１０μｍより小さいと、嵩が大きくなるため、脆く割れやすくなり加工が難しくなるおそれがある。また、熱伝導パスの形成が難しくなり、熱伝導性が劣るおそれがある。一方、Ｆ２の平均粒子径が１００μｍより大きいと、Ｆ１との平均粒子径が近くなりすぎるため、熱伝導フィラーが密に充填されにくく、その結果、熱伝導パスが形成されにくくなり、熱伝導性が劣るおそれがある。 If the average particle size of F1 is less than 120 μm, the amount of powder increases, resulting in a sheet that is likely to crack and molding (for example, press vulcanization molding) may become difficult. On the other hand, when the average particle size of F1 is larger than 500 μm, the number of particles having a large particle size increases, making it difficult to form a heat conduction path, which may result in poor thermal conductivity. If the average particle size of F2 is less than 10 μm, the bulk becomes large, which may make processing difficult due to fragility and cracking. Moreover, it becomes difficult to form a heat conduction path, and there is a possibility that the heat conductivity is deteriorated. On the other hand, when the average particle size of F2 is larger than 100 μm, the average particle size of F2 is too close to that of F1, so that the thermally conductive filler is difficult to be densely packed. may be inferior.
　本発明において、Ｆ１、Ｆ２の平均粒子径は、粒子径分布を累積分布としたとき、体積基準の累積値が５０％となる点の粒子径（Ｄ５０）であり、レーザー回折／散乱式粒子径分布測定装置（例えば堀場製作所製　ＬＡ－９２０）の湿式法にて測定することができる。なお、放熱材シートから、充填されている熱伝導フィラーの平均粒子径を求めるには、例えば、シート断面を適宜観察可能な拡大鏡を用いて実測することができる。 In the present invention, the average particle size of F1 and F2 is the particle size (D50) at the point where the volume-based cumulative value is 50% when the particle size distribution is a cumulative distribution, and is a laser diffraction/scattering particle size. It can be measured by a wet method using a distribution measuring device (eg LA-920 manufactured by Horiba Ltd.). In order to obtain the average particle size of the thermally conductive filler filled in the heat dissipating material sheet, for example, a magnifying glass capable of appropriately observing the cross section of the sheet can be used for actual measurement.
　また、フッ素ゴム組成物におけるＦ１とＦ２の質量比（Ｆ１：Ｆ２）は、（２：１）～（５：１）であり、好ましくは（２：１）～（４：１）であり、より好ましくは（３：１）～（４：１）である。Ｆ２の質量を１とした時、Ｆ１の質量が２よりも小さいと（Ｆ１の量が少なすぎる場合）、平均粒子径が小さい粒子が多くなるため熱伝導パスが形成されにくくなり、熱伝導性が低下するおそれがある。また、Ｆ１の質量が５より大きいと（Ｆ１の量が多すぎる場合）、平均粒子径が小さい粒子が少なくなるため、平均粒子径が大きい粒子同士の間隙に入る粒子が少なくなり、熱伝導パスが形成されにくくなり、熱伝導性が低下するおそれがある。 Further, the mass ratio (F1:F2) of F1 and F2 in the fluororubber composition is (2:1) to (5:1), preferably (2:1) to (4:1), More preferably (3:1) to (4:1). When the mass of F2 is 1, if the mass of F1 is less than 2 (when the amount of F1 is too small), the number of particles with a small average particle size increases, making it difficult to form a heat conduction path, resulting in poor thermal conductivity. may decrease. Also, if the mass of F1 is greater than 5 (when the amount of F1 is too large), the number of particles with a small average particle size decreases, so the number of particles that enter the gap between particles with a large average particle size decreases, resulting in a heat conduction path becomes difficult to form, and there is a risk that the thermal conductivity will decrease.
　特に、Ｆ１の含有量をＦ２の含有量よりも多くすることで、効率的に熱伝導パスが形成されやすくなる。これは、平均粒子径が大きいＦ１の間に平均粒子径が小さいＦ２が入り込むことで、熱伝導パスが形成されやすくなると推測される。更にＦ１とＦ２の質量比（Ｆ１：Ｆ２）を（２：１）～（５：１）とすることで、平均粒子径が大きいＦ１の粒子の間に入り込む平均粒子径が小さいＦ２の粒子の割合が最適となり、熱伝導パスが形成されて熱伝導性が向上する。また、シート中において、微小な空隙が発生することなども抑制できる。 In particular, by making the content of F1 greater than the content of F2, it becomes easier to efficiently form a heat conduction path. It is presumed that this is because F2, which has a small average particle size, enters between F1, which has a large average particle size, so that a heat conduction path is likely to be formed. Furthermore, by setting the mass ratio (F1:F2) of F1 and F2 to (2:1) to (5:1), the particles of F2 with a small average particle size that enter between the particles of F1 with a large average particle size The optimum ratio results in the formation of thermal conduction paths and improved thermal conductivity. In addition, it is possible to suppress the generation of minute voids in the sheet.
　上記形態において、複数の熱伝導フィラーは２種類（Ｆ１、Ｆ２）に限らず、更に、平均粒子径が異なる熱伝導フィラーを含んでいてもよい。この場合、複数の熱伝導フィラーのうち、少なくとも大小関係にある２種の粒子間において、上記の関係などを満たすことが好ましい。 In the above embodiment, the plurality of thermally conductive fillers are not limited to two types (F1, F2), and may further include thermally conductive fillers with different average particle sizes. In this case, it is preferable that at least two types of particles having a size relationship among the plurality of thermally conductive fillers satisfy the above relationship.
　本発明において、熱伝導フィラーの含有量（異なる平均粒子径を持つ複数の熱伝導フィラーを用いる場合はそれらの合計量）は、フッ素ゴム組成物全体に対して５０体積％以上であり、好ましくは５０体積％超であり、より好ましくは５２体積％以上であり、特に好ましくは５５体積％以上である。これにより、シート中に熱伝導パスを形成しやすくなり、優れた熱伝導性を発揮できる。一方で、熱伝導フィラーの含有量が大きくなるとゴムの混練が困難になったり、成形しにくくなる傾向があることから、熱伝導フィラーの上記含有量は、フッ素ゴム組成物全体に対して７５体積％以下が好ましく、７０体積％以下であってもよく、６５体積％以下であってもよい。 In the present invention, the content of the thermally conductive filler (the total amount thereof when using a plurality of thermally conductive fillers having different average particle sizes) is 50% by volume or more relative to the entire fluororubber composition, preferably It is more than 50% by volume, more preferably 52% by volume or more, and particularly preferably 55% by volume or more. This makes it easier to form a heat conduction path in the sheet, thereby exhibiting excellent heat conductivity. On the other hand, if the content of the thermally conductive filler becomes large, it tends to be difficult to knead the rubber or difficult to mold. % or less, may be 70 volume % or less, or may be 65 volume % or less.
　本発明の放熱材シートは絶縁性を有しており、ＪＩＳ　Ｃ　２１１０－１に規定される絶縁破壊電圧が４．５０ｋＶ以上、または絶縁破壊強さが３．５０ｋＶ／ｍｍ以上であることが好ましい。上記絶縁破壊電圧、絶縁破壊強さを実現するために、上記フッ素ゴム組成物は導電性フィラーを含まないことが好ましい。導電性フィラーは、例えば、黒鉛粉末、導電性カーボンブラック、カーボンナノチューブ、フラーレンなどの固体炭素材料や、銅粉、銀粉、鉄粉などの金属粉末、導電性酸化錫、導電性酸化チタンなどの導電性金属酸化物などである。 The heat dissipating material sheet of the present invention has insulating properties, and preferably has a dielectric breakdown voltage of 4.50 kV or higher or a dielectric breakdown strength of 3.50 kV/mm or higher as defined in JIS C 2110-1. . In order to achieve the above dielectric breakdown voltage and dielectric breakdown strength, the fluororubber composition preferably does not contain a conductive filler. Examples of conductive fillers include solid carbon materials such as graphite powder, conductive carbon black, carbon nanotubes, and fullerene; metal powders such as copper powder, silver powder, and iron powder; and conductive materials such as conductive tin oxide and conductive titanium oxide. metal oxides and the like.
　本発明の放熱材シートにおいて、上述したフッ素ゴムは架橋されていることが好ましい。架橋方法としては、例えばプレス加硫などの化学架橋を行うことができる。プレス加硫に用いる加硫剤には、ジクミルパーオキサイド、２，５－ジメチル－２，５－ビス（ｔ－ブチルパーオキシ）ヘキサン、１，３－ビス－（ｔ－ブチルペルオキシ－イソプロピル）ベンゼン、ｔ－ブチルクミルパーオキサイド、ジ－ｔ－ブチルパーオキサイドなどの有機過酸化物を用いることができる。加硫剤の配合量は、フッ素ゴム１００質量部に対して０．５質量部～３質量部が好ましい。 In the heat dissipating material sheet of the present invention, the above-mentioned fluororubber is preferably crosslinked. As a cross-linking method, for example, chemical cross-linking such as press vulcanization can be performed. Vulcanizing agents used for press vulcanization include dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,3-bis-(t-butylperoxy-isopropyl) Organic peroxides such as benzene, t-butylcumyl peroxide, di-t-butylperoxide can be used. The content of the vulcanizing agent is preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the fluororubber.
　なお、架橋方法はプレス加硫に限らず、通常の架橋方法を採用でき、例えば放射線架橋法を行ってもよい。放射線架橋では、電子線、γ線、Ｘ線などが用いられる。 The cross-linking method is not limited to press vulcanization, and a normal cross-linking method can be employed, for example, a radiation cross-linking method may be performed. Electron beams, γ-rays, X-rays, and the like are used in radiation crosslinking.
　上記フッ素ゴム組成物には、本発明の効果を阻害しない範囲で、フッ素ゴム、軟化剤、熱伝導フィラー、および加硫剤以外に、その他の添加剤を配合することができる。例えば、老化防止剤、加硫促進剤、補強剤、着色剤などを配合できる。 In addition to the fluororubber, softening agent, heat conductive filler, and vulcanizing agent, other additives can be added to the fluororubber composition as long as they do not impair the effects of the present invention. For example, anti-aging agents, vulcanization accelerators, reinforcing agents, coloring agents and the like can be blended.
　本発明の放熱材シートは優れた熱伝導性を有しており、熱伝導率は３．０Ｗ／ｍＫ以上が好ましく、４．５Ｗ／ｍＫ以上がより好ましく、５．０Ｗ／ｍＫ以上がより好ましい。例えば、熱伝導率は２０Ｗ／ｍＫ以下であり、１５Ｗ／ｍＫ以下であってもよい。本発明において、放熱材シートの熱伝導率は、熱線法で測定した値とする。例えば、厚さ１ｍｍの試験片を熱伝導率計によって測定することで得られる。 The heat dissipation material sheet of the present invention has excellent thermal conductivity, and the thermal conductivity is preferably 3.0 W/mK or higher, more preferably 4.5 W/mK or higher, and more preferably 5.0 W/mK or higher. . For example, the thermal conductivity is 20 W/mK or less, and may be 15 W/mK or less. In the present invention, the thermal conductivity of the heat dissipating material sheet is the value measured by the hot wire method. For example, it can be obtained by measuring a test piece with a thickness of 1 mm with a thermal conductivity meter.
　本発明の放熱材シートの硬度は特に限定されないが、ＪＩＳ　Ｋ６２５３に規定されるタイプＤデュロメータによる硬度が２０～６０が好ましく、２０～５０がより好ましい。これにより、良好な柔軟性を付与でき、狭小スペースや曲面などの複雑な形状にもフィットさせることができ、幅広い用途に適用できる。 Although the hardness of the heat dissipating material sheet of the present invention is not particularly limited, it preferably has a hardness of 20 to 60, more preferably 20 to 50, according to the type D durometer specified in JIS K6253. As a result, good flexibility can be imparted, and complicated shapes such as narrow spaces and curved surfaces can be fitted, making it applicable to a wide range of applications.
　次に、本発明の放熱材シートを製造する方法について説明する。 Next, a method for manufacturing the heat dissipating material sheet of the present invention will be described.
　上記放熱材シートは、例えば、（１）原料組成物を調製して、（２）調製した原料組成物を成形、架橋することによって製造することができる。上記（１）の原料組成物の調製は、例えば、フッ素ゴム、軟化剤、熱伝導フィラーなどの各種原材料を２本ロールで練り込むことなどによって行う。 For example, the heat dissipation material sheet can be produced by (1) preparing a raw material composition, and (2) molding and crosslinking the prepared raw material composition. The raw material composition of (1) is prepared, for example, by kneading various raw materials such as fluororubber, softening agent, and heat-conductive filler with two rolls.
　一方で、本発明の放熱材シートは、熱伝導フィラーの含有量が多いため、練り込み作業が比較的困難になる傾向がある。そのため、本発明では、各種原材料を含む溶解液を作製した後、乾燥、成形、加硫して、製造することが好ましい。 On the other hand, since the heat dissipating material sheet of the present invention contains a large amount of thermally conductive filler, the kneading operation tends to be relatively difficult. Therefore, in the present invention, it is preferable to manufacture by drying, molding and vulcanizing after preparing a solution containing various raw materials.
　具体的には、熱伝導フィラーおよび軟化剤を容器に入れて、溶剤を加えて混合、分散させた後、予め混練りロールにて混練りしたフッ素ゴムを含むコンパウンドをその容器に入れ、溶解させる。この場合、一度に各種原料を添加するのではなく、熱伝導フィラーと軟化剤を溶剤中で分散させた状態のところへ、コンパウンドを添加することで、ベースとなるフッ素樹脂への熱伝導フィラーの分散性を向上させることができると考えられる。
　そして、得られた溶解液を型枠に所定量流し込み、溶剤を揮発させる。その後、乾燥物をプレスにて加硫成形して、放熱材シートが得られる。なお、得られた放熱材シートは、必要に応じてアニール処理を行ってもよい。 Specifically, a heat conductive filler and a softening agent are placed in a container, a solvent is added and mixed and dispersed, and then a compound containing fluororubber that has been kneaded in advance by a kneading roll is placed in the container and dissolved. . In this case, instead of adding various raw materials at once, by adding a compound to the state where the thermal conductive filler and softening agent are dispersed in the solvent, the thermal conductive filler to the base fluororesin is added. It is thought that dispersibility can be improved.
Then, a predetermined amount of the obtained solution is poured into the mold to volatilize the solvent. After that, the dried product is vulcanized by pressing to obtain a heat dissipating material sheet. The obtained heat dissipation material sheet may be annealed as necessary.
　なお、成形方法としては、押出し成形、射出成形、トランスファー成形などを行うことができるが、プレス成形が好ましく、放熱材シートはプレス成形体であることが好ましい。 As a molding method, extrusion molding, injection molding, transfer molding, and the like can be performed, but press molding is preferable, and the heat radiation material sheet is preferably a press-molded body.
　放熱材シートのシート厚さは特に限定されず、例えば０．５ｍｍ以上であり、好ましくは１ｍｍ以上である。一方で、狭小スペースへの設置や形状自由度の観点からシート厚さは薄いことが好ましく、シート厚さは例えば５ｍｍ以下であり、３ｍｍ以下であってもよい。 The sheet thickness of the heat radiation material sheet is not particularly limited, and is, for example, 0.5 mm or more, preferably 1 mm or more. On the other hand, the sheet thickness is preferably thin from the viewpoint of installation in a narrow space and flexibility of shape, and the sheet thickness is, for example, 5 mm or less, and may be 3 mm or less.
実施例１～６、比較例１～５
　各試験例のフッ素ゴム組成物の組成は表１および表２に記載のとおりである。各試験例では、軟化剤として液状フッ素ゴムを用いた。また、熱伝導フィラーとしては、平均粒子径が異なる３種の窒化ホウ素Ａ～Ｃおよび平均粒子径が異なる３種の酸化アルミニウム（アルミナ）Ａ～Ｃを用い、これらの中から１種または２種を組み合わせ、平均粒子径が大きい方をＦ１、平均粒子径が小さい方をＦ２とした。なお、窒化ホウ素粒子には鱗片状の一次粒子を造粒した造粒体またはその凝集体を用いた。表１および表２中の「熱伝導フィラー（Ｆ１＋Ｆ２）の体積％」は、フッ素ゴム組成物全体に対する、熱伝導フィラー全体の体積％を示している。 Examples 1-6, Comparative Examples 1-5
The composition of the fluororubber composition of each test example is as shown in Tables 1 and 2. In each test example, a liquid fluororubber was used as a softening agent. In addition, as the heat conductive filler, three types of boron nitride A to C with different average particle sizes and three types of aluminum oxide (alumina) A to C with different average particle sizes are used, and one or two of these are used. were combined, and the one with a larger average particle size was designated as F1, and the one with a smaller average particle size was designated as F2. As the boron nitride particles, granules obtained by granulating scale-like primary particles or aggregates thereof were used. "Volume % of thermally conductive filler (F1+F2)" in Tables 1 and 2 indicates the volume % of the entire thermally conductive filler with respect to the entire fluororubber composition.
　各熱伝導フィラーの平均粒子径を以下に示す。
　窒化ホウ素Ａ：３００μｍ～５００μｍ
　窒化ホウ素Ｂ：５５μｍ～６５μｍ
　窒化ホウ素Ｃ：２５μｍ
　アルミナＡ　：６００μｍ
　アルミナＢ　：３５５μｍ
　アルミナＣ　：５３μｍ The average particle size of each heat conductive filler is shown below.
Boron nitride A: 300 μm to 500 μm
Boron nitride B: 55 μm to 65 μm
Boron nitride C: 25 μm
Alumina A: 600 μm
Alumina B: 355 μm
Alumina C: 53 μm
　以下の手順により、各試験シートを作製した。
１．予め混練りロールにて、フッ素ゴム、加硫剤などを混練りしてコンパウンドを得た。
２．容器に窒化ホウ素またはアルミナ、液状フッ素ゴムなどを計量し、メチルエチルケトン（ＭＥＫ）を加えて混合、分散させた後、上記コンパウンドを容器に入れ、溶解させた。
３．得られた溶解液を型枠に所定量を流し込み、真空脱泡処理した後、溶剤が揮発するまで乾燥した。
４．乾燥したシートをプレスにて加硫成形した後、アニール処理して、試験シートを得た。 Each test sheet was produced by the following procedure.
1. A compound was obtained by previously kneading the fluororubber, the vulcanizing agent, and the like with a kneading roll.
2. Boron nitride or alumina, liquid fluororubber, etc. were weighed in a container, methyl ethyl ketone (MEK) was added, mixed and dispersed, and then the above compound was placed in a container and dissolved.
3. A predetermined amount of the resulting solution was poured into a mold, subjected to a vacuum defoaming treatment, and then dried until the solvent was volatilized.
4. After the dried sheet was vulcanized by pressing, it was annealed to obtain a test sheet.
　得られた各試験シートを用いて常態における物性評価として、熱伝導率、引張強さ、切断時伸び、硬さ（タイプＤ）をそれぞれ測定した。熱伝導率は、各試験シートから寸法（５０ｍｍ×１００ｍｍ×１ｍｍ）の試料を切り出した後、ＪＩＳ　Ｒ２６１６に規定される熱線法に準じて、２３℃にて測定した。引張強さおよび切断時伸びはＪＩＳ　Ｋ６２５１に規定される試験法に準拠して測定した。硬さはＪＩＳ　Ｋ６２５３（タイプＤデュロメーター）に規定される試験法に準拠して測定した。 Using each test sheet obtained, thermal conductivity, tensile strength, elongation at break, and hardness (type D) were measured as physical property evaluations in the normal state. The thermal conductivity was measured at 23° C. according to the hot wire method specified in JIS R2616 after cutting out a sample of dimensions (50 mm×100 mm×1 mm) from each test sheet. Tensile strength and elongation at break were measured according to the test method specified in JIS K6251. The hardness was measured according to the test method specified in JIS K6253 (type D durometer).
　また、熱老化による物性変化を確認するべく、熱老化試験（条件１：２００℃で７２時間、条件２：２２０℃で７２時間）を実施して、熱老化試験後の各物性を上記のように測定した。結果を表１および表２に示す。なお、各物性評価において、表中の「－」は未測定を表している。 In addition, in order to confirm changes in physical properties due to heat aging, a heat aging test (condition 1: 72 hours at 200 ° C., condition 2: 72 hours at 220 ° C.) was performed, and each physical property after the heat aging test was evaluated as described above. measured to Results are shown in Tables 1 and 2. In each physical property evaluation, "-" in the table indicates unmeasured.
　また、実施例２の試験シートについて、ＪＩＳ　Ｃ　２１１０－１に規定される試験法に準拠して測定したところ、絶縁破壊電圧が４．９９ｋＶであり、絶縁破壊強さが３．８４ｋＶ／ｍｍであった。 In addition, when the test sheet of Example 2 was measured according to the test method specified in JIS C 2110-1, the dielectric breakdown voltage was 4.99 kV and the dielectric breakdown strength was 3.84 kV/mm. there were.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１および表２に示すように、熱伝導フィラーの含有量が大きくなると、常態時における熱伝導率が向上する傾向が見られた（実施例１、３、４）。また、熱伝導フィラーとして平均粒子径が１種類の熱伝導フィラーを用いる場合（比較例１）よりも、平均粒子径が２種類の窒化ホウ素粒子を組み合わせた場合（実施例４）の方が、熱伝導率が大きく上昇した。また、液状フッ素ゴムの含有量が多くなると、熱伝導率が上昇した。上記の製造方法は、窒化ホウ素と液状フッ素ゴムとを溶剤中で予め分散させており、液状フッ素ゴムを多く用いることで、シート中における熱伝導フィラーの分散性が良好になった可能性が考えられる。 As shown in Tables 1 and 2, there was a tendency for the thermal conductivity in the normal state to improve as the content of the thermally conductive filler increased (Examples 1, 3, and 4). In addition, when boron nitride particles having two types of average particle sizes are combined (Example 4) than when using a thermally conductive filler having one type of average particle size as the thermally conductive filler (Comparative Example 1), The thermal conductivity increased greatly. Moreover, when the content of the liquid fluororubber increased, the thermal conductivity increased. In the above manufacturing method, boron nitride and liquid fluororubber are dispersed in advance in the solvent, and it is possible that the use of a large amount of liquid fluororubber has improved the dispersibility of the thermally conductive filler in the sheet. be done.
　なお、平均粒子径が２種類の窒化ホウ素粒子を組み合わせた場合であっても、平均粒子径が比較的小さいもの同士を組み合わせた場合（比較例２）は、加硫プレス時に割れが発生し、成形できなかった。つまり、嵩が増し加工性が低下する結果となった。なお、比較例２については、各種物性の評価ができなかった。 Even when two types of boron nitride particles having an average particle size are combined, when those having a relatively small average particle size are combined (Comparative Example 2), cracking occurs during vulcanization press, could not be molded. That is, the result was that the bulk increased and the workability decreased. For Comparative Example 2, various physical properties could not be evaluated.
　また、熱伝導フィラーとして、窒化ホウ素を用いた場合の方が、アルミナを用いた場合よりも良好な結果が得られた。アルミナの比重は、窒化ホウ素よりも大きく（例えば、窒化ホウ素２．１５ｇ／ｃｍ３、アルミナ３．９８ｇ／ｃｍ３）、窒化ホウ素に比べてアルミナは溶液中で沈降しやすいといえ、シート中におけるアルミナの偏りが熱伝導率の低下に繋がったと考えられる。また、アルミナを用いた場合、シートの切断を行ないにくく、後加工性という点でも窒化ホウ素の方が好ましい。 Moreover, better results were obtained when boron nitride was used as the thermally conductive filler than when alumina was used. The specific gravity of alumina is higher than that of boron nitride (for example, boron nitride is 2.15 g/cm 3 and alumina is 3.98 g/cm 3 ). It is considered that the uneven distribution of alumina led to the decrease in thermal conductivity. Further, when alumina is used, boron nitride is more preferable in terms of post-workability because it is difficult to cut the sheet.
　また、表１に示すように、実施例１～３、５は、高温環境下に長期間置かれても劣化することなく、熱伝導率を維持していることが分かる。特に、実施例１は、熱伝導率は良好に維持されており、高温劣化が防止されていた。 In addition, as shown in Table 1, Examples 1 to 3 and 5 maintain their thermal conductivity without deterioration even when placed in a high temperature environment for a long period of time. In particular, in Example 1, the thermal conductivity was well maintained, and high-temperature deterioration was prevented.
　本発明の放熱材シートは、耐熱性、柔軟性、および絶縁性を有するとともに、優れた熱伝導性を有するので、電子機器などにおいて使用され、熱源が発生する熱を速やかに伝達させることができる。 The heat dissipating material sheet of the present invention has heat resistance, flexibility, insulation, and excellent thermal conductivity, so it is used in electronic devices and the like, and can quickly transmit heat generated by a heat source. .
　　１　　放熱材シート 　　1　　Heat dissipation material sheet

Claims (7)

  1. 　フッ素ゴム組成物からなる放熱材シートであって、
    　前記フッ素ゴム組成物は、フッ素ゴムと、軟化剤と、熱伝導フィラーとを含み、
    　前記熱伝導フィラーの含有量は、前記フッ素ゴム組成物全体に対して５０体積％以上であり、
    　前記熱伝導フィラーは、平均粒子径が異なる複数の熱伝導フィラーを含み、前記複数の熱伝導フィラーのうち、平均粒子径が大きい熱伝導フィラーを第１の熱伝導フィラー（Ｆ１）とし、平均粒子径が小さい熱伝導フィラーを第２の熱伝導フィラー（Ｆ２）とした場合、
    　前記第１の熱伝導フィラー（Ｆ１）の平均粒子径は１２０μｍ～５００μｍであり、前記第２の熱伝導フィラー（Ｆ２）の平均粒子径は１０μｍ～１００μｍであり、前記フッ素ゴム組成物における前記第１の熱伝導フィラー（Ｆ１）と前記第２の熱伝導フィラー（Ｆ２）の質量比（Ｆ１：Ｆ２）は（２：１）～（５：１）であることを特徴とする放熱材シート。     A heat dissipating material sheet made of a fluororubber composition,
    The fluororubber composition includes a fluororubber, a softening agent, and a heat conductive filler,
    The content of the thermally conductive filler is 50% by volume or more with respect to the entire fluororubber composition,
    The thermally conductive filler includes a plurality of thermally conductive fillers having different average particle sizes. Among the plurality of thermally conductive fillers, the thermally conductive filler having a larger average particle size is used as the first thermally conductive filler (F1), and the average particle size is When a thermally conductive filler with a small diameter is used as the second thermally conductive filler (F2),
    The average particle size of the first thermally conductive filler (F1) is 120 μm to 500 μm, and the average particle size of the second thermally conductive filler (F2) is 10 μm to 100 μm. A heat dissipating material sheet, wherein the mass ratio (F1:F2) of the first thermally conductive filler (F1) and the second thermally conductive filler (F2) is (2:1) to (5:1).
  2. 　前記熱伝導フィラーの含有量は、前記フッ素ゴム組成物全体に対して６５体積％以下であることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the content of said thermally conductive filler is 65% by volume or less with respect to the entire fluororubber composition.
  3. 　前記第１の熱伝導フィラー（Ｆ１）の平均粒子径は３００μｍ～５００μｍであることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the average particle size of the first thermally conductive filler (F1) is 300 µm to 500 µm.
  4. 　前記第２の熱伝導フィラー（Ｆ２）の平均粒子径は２０μｍ～７０μｍであることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the average particle size of the second thermally conductive filler (F2) is 20 µm to 70 µm.
  5. 　前記熱伝導フィラーが窒化ホウ素、窒化アルミニウム、酸化アルミニウム、および酸化マグネシウムから選択される少なくとも１種であることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the thermally conductive filler is at least one selected from boron nitride, aluminum nitride, aluminum oxide, and magnesium oxide.
  6. 　前記軟化剤は、前記フッ素ゴム１００質量部に対して２０質量部～６０質量部含まれることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the softening agent is contained in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the fluororubber.
  7. 　前記放熱材シートのシート厚さが１ｍｍ以上であることを特徴とする請求項１記載の放熱材シート。 The heat dissipating material sheet according to claim 1, wherein the sheet thickness of the heat dissipating material sheet is 1 mm or more.
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JP2020053531A (en) * 2018-09-26 2020-04-02 スリーエム イノベイティブ プロパティズ カンパニー Thermally conductive sheet precursor, thermally conductive sheet obtained from the precursor, and method for manufacturing the same

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* Cited by examiner, † Cited by third party
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US5781412A (en) * 1996-11-22 1998-07-14 Parker-Hannifin Corporation Conductive cooling of a heat-generating electronic component using a cured-in-place, thermally-conductive interlayer having a filler of controlled particle size
JP2016522298A (en) * 2013-06-19 2016-07-28 スリーエム イノベイティブ プロパティズ カンパニー Components produced from polymer / boron nitride compounds, polymer / boron nitride compounds to produce such components, and uses thereof
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