JP2018053018A - Heat-radiation foamed sheet and adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-radiation foamed sheet that has excellent flexibility and high heat radiation properties even when it is made thin.SOLUTION: A heat-radiation foamed sheet has an elastomer (A), a tabular filler (B) dispersed in the elastomer (A), and a spherical filler (C). Relative to the total volume of the heat-radiation foamed sheet, the elastomer (A) is 40-70 vol.%, tabular filler (B) is 10-35 vol.%, and spherical filler (C) is 15-35 vol.%.SELECTED DRAWING: None

Description

  The present invention relates to a heat-dissipating foam sheet and an adhesive tape, and relates to, for example, a heat-dissipating foam sheet that is used inside an electronic device and dissipates heat to the outside, and an adhesive tape having the heat-dissipating foam sheet.

In the vicinity of display devices used in various electronic devices such as personal computers, mobile phones, and electronic papers, and other electronic components, shock absorbers for absorbing shock and vibration, to fill gaps to be dustproof, waterproof, etc. The sealing material is used. In addition, in electronic devices, integrated electronic components generate heat and may cause failure. Therefore, shock absorbers and seal materials are required to have heat dissipation performance to suppress heat generation of electronic devices. is there.
Conventionally, as a foam having both heat dissipation and shock absorption or sealing properties, for example, as disclosed in Patent Document 1, a heat dissipation foam obtained by foaming an elastomer containing a thermally conductive filler such as aluminum oxide It has been known.

JP 2013-231166 A

However, electronic devices, particularly portable electronic devices such as smartphones, are becoming smaller year by year, and the space in which shock absorbers and sealing materials are arranged is narrower. Therefore, heat dissipation foams are required to have higher heat dissipation properties while being thin and having good flexibility.
This invention is made | formed in view of the above situation, Comprising: Even if it is thin, the subject of this invention is providing a heat dissipation foam sheet which has a favorable softness | flexibility and high heat dissipation.

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by blending a predetermined amount of two kinds of spherical fillers and plate-like fillers into the elastomer as thermal conductive fillers, and have completed the following invention. . The present invention provides the following [1] to [9].
[1] An elastomer (A), a plate-like filler (B) dispersed in the elastomer (A), and a spherical filler (C),
A heat-dissipating foam sheet in which the elastomer (A) is 40 to 70% by volume, the plate-like filler (B) is 10 to 35% by volume, and the spherical filler (C) is 15 to 35% by volume on the basis of the total volume of the heat-dissipating foam sheet.
[2] At least one plate filler (B) and spherical filler (C) each selected from the group consisting of silica, aluminum oxide, magnesium oxide, boron nitride, talc, aluminum nitride, carbon-based filler, and conductive metal particles. The heat dissipating foam sheet according to the above [1], which is a seed.
[3] The heat dissipating foam sheet according to the above [1] or [2], wherein the plate-like filler (B) has an average particle size of 5 to 100 μm and the spherical filler (C) has an average particle size of 10 to 150 μm.
[4] The heat dissipating foam sheet according to any one of [1] to [3], wherein the spherical filler (C) has an average particle size larger than that of the plate-like filler (B).
[5] The heat dissipation foamed sheet according to any one of [1] to [4], wherein the volume percent of the plate-like filler (B) is higher than the volume percent of the spherical filler (C).
[6] The heat-dissipating foam sheet according to any one of [1] to [5], which is foamed with a pyrolytic foaming agent.
[7] The heat dissipation foam sheet according to any one of [1] to [6], wherein the thickness is 0.05 to 1 mm.
[8] The heat radiation foam sheet according to any one of [1] to [7], wherein the apparent density is 0.5 to 2.0 g / cm ³ .
[9] A pressure-sensitive adhesive tape comprising the heat-dissipating foam sheet according to any one of [1] to [8] above and an adhesive layer provided on at least one surface of the heat-dissipation foam sheet.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is thin, it is possible to provide the heat dissipation foam sheet which has a favorable softness | flexibility and has high heat dissipation.

Hereinafter, the present invention will be described in more detail using embodiments.
<Heat dissipation foam sheet>
The heat dissipation foam sheet of the present invention is a foam containing an elastomer (A), a plate-like filler (B), and a spherical filler (C). In the heat dissipating foam sheet, in addition to a large number of bubbles, a plate-like filler (B) and a spherical filler (C) are dispersed in the elastomer (A).

Hereinafter, each component used for the heat dissipation foam sheet will be described in more detail.
[Elastomer (A)]
The elastomer used for the heat radiation foam sheet is not particularly limited, but acrylonitrile butadiene rubber, ethylene propylene diene rubber, ethylene propylene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene block copolymer, hydrogenated styrene. -Butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, and the like. Among these, acrylonitrile butadiene rubber and ethylene propylene diene rubber are preferable, and ethylene propylene diene rubber is preferable in order to ensure high flexibility even when a relatively large amount of the plate filler (B) and spherical filler (C) is blended. More preferred. These elastomers may be used alone or in a combination of two or more.
In addition, these elastomers may be liquid elastomers that are liquid at room temperature (23 ° C.) and normal pressure (1 atm), may be solid, or may be a mixture thereof. However, it is preferred to use a mixture.

[Filler (B), (C)]
The plate-like filler (B) and spherical filler (C) used for the heat dissipation foam sheet are heat conductors. Here, the plate-like filler (B) is a filler in the form of flakes and scaly, and the major axis of each filler is sufficiently larger than the thickness, for example, the ratio of the thickness to the major axis is 2 or more, Preferably it is 3 or more.
In addition, the spherical filler (C) has a filler shape close to a sphere and a sphere, and the ratio of the major axis to the minor axis of each filler is close to 1 or 1, and the ratio is, for example, 0.6 to 1.7. , Preferably 0.8 to 1.5.
In the present invention, in addition to the plate-like filler (B), the spherical filler (C) is blended at a volume% described later, whereby the heat dissipation is excellent. Although the reason is not certain, it is presumed that the plate-like filler (B) is oriented in the thickness direction by the spherical filler (C) and bubbles formed by foaming. Since the plate-like filler (B) has a high thermal conductivity in the length direction, the heat-dissipating foam sheet has an improved thermal conductivity in the thickness direction because the plate-like filler (B) is oriented in the thickness direction. Thereby, the heat dissipation of the heat dissipating foam sheet is excellent.

For example, the plate filler (B) and the spherical filler (C) preferably have a thermal conductivity of 30 W / m · K or more, but the plate filler (B) has a thermal conductivity of the spherical filler (C). It is preferable that the thermal conductivity is higher. By increasing the thermal conductivity of the plate-like filler, the thermal conductivity in the thickness direction of the heat radiating foam sheet can be easily increased, and the heat dissipation can be easily improved.
Further, the thermal conductivity of the plate filler (B) is more preferably 100 to 400 W / m · K, and further preferably 150 to 350 W / m · K. On the other hand, the thermal conductivity of the spherical filler (C) is more preferably 30 to 150 W / m · K, and further preferably 40 to 100 W / m · K.
In addition, the heat conductivity of a filler can be measured by the advance wirecraft thermal conductivity measuring device TC-1000 made from Advance Riko Co., Ltd.

The plate-like filler (B) and the spherical filler (C) are each selected from, for example, silica, aluminum oxide, magnesium oxide, boron nitride, talc, aluminum nitride, carbon-based filler, and conductive metal particles such as copper and aluminum. At least one kind. In addition, as a carbon-type filler, a graphite, a graphene, etc. are mentioned, However, A graphene is preferable. As the plate-like filler (B) and the spherical filler (C), fillers made of the same kind of material may be used, or fillers made of different kinds of materials may be used.
Further, among the above, the plate filler (B) is more preferably boron nitride, and the spherical filler (C) is more preferably aluminum oxide or magnesium oxide, and the plate filler (B) is boron nitride. The spherical filler (C) is particularly preferably magnesium oxide.
In addition, a spherical filler (C) and a plate-shaped filler (B) may each be used individually by 1 type, and may use 2 or more types together.

The average particle size of the spherical filler (C) is preferably larger than the average particle size of the plate filler (B). It is considered that the average particle size of the spherical filler (C) is larger than the average particle size of the plate-like filler (B), so that the plate-like filler (B) can be easily oriented in the thickness direction. Heat dissipation is improved. The average particle diameter of the plate filler (B) is, for example, 5 to 100 μm, preferably 10 to 50 μm, and more preferably 15 to 40 μm. On the other hand, the average particle diameter of the spherical filler (C) is, for example, 10 to 150 μm, preferably 20 to 100 μm, more preferably greater than 40 μm and 80 μm or less.
The plate-like filler (B) has a relatively small average particle size, thereby improving the foamability and improving the smoothness of the surface of the heat radiating foam sheet. Moreover, various performances, such as thermal conductivity and a softness | flexibility, can be improved with sufficient balance by making the average particle diameter of a plate-like filler (B) and a spherical filler (C) into the said range.

[volume%]
In the heat dissipating foam sheet, the elastomer (A) is 40 to 70% by volume, the plate filler (B) is 10 to 35% by volume, and the spherical filler (C) is 15 to 35% by volume on the basis of the total volume. Each component is blended.
When the elastomer (A) is less than 40% by volume, the heat dissipating foam sheet has problems such as difficulty in forming into a sheet shape and loss of flexibility. Moreover, when it exceeds 70 volume%, it will become difficult to mix | blend sufficient quantity of a filler and to raise thermal conductivity. When the plate-like filler (B) is less than 10% by volume, the heat conductivity of the heat radiating foam sheet, particularly the heat conductivity in the thickness direction, is not sufficiently high. The foamability of the sheet is deteriorated, foaming is not performed properly, and the smoothness of the heat radiating foam sheet surface is impaired. Furthermore, when the spherical filler (C) is less than 15% by mass, it becomes difficult to orient the plate-like filler (B) in the thickness direction, and it becomes difficult to increase the thermal conductivity of the heat dissipating foam sheet. And it becomes difficult to make thermal conductivity high, making foamability favorable. Moreover, when it exceeds 35 volume%, foamability will worsen, the smoothness of the heat-radiation foam sheet surface will be impaired, and also troubles, such as being unable to mix | blend many plate-like fillers (B), will arise.

In the heat dissipating foam sheet, each component is blended so that the elastomer (A) is 40 to 60% by volume, the plate filler (B) is 15 to 35% by volume, and the spherical filler (C) is 18 to 35% by volume. It is preferable. By setting it as such volume%, it becomes possible to improve foamability, thermal conductivity, a softness | flexibility, etc. with sufficient balance.
Moreover, in order to improve thermal conductivity more, it is more preferable that the volume% of a plate-like filler (B) is higher than the volume% of a spherical filler. And from the viewpoint of further improving the thermal conductivity, in the heat dissipating foamed sheet, the elastomer (A) is 40 to 60% by volume, the plate filler (B) is 25 to 35% by volume, and the spherical filler (B) Each component is preferably blended so that C) is 18 to 24% by volume.

  The volume% of the components (A), (B), and (C) is calculated on the basis of the total volume of the heat radiating foam sheet. The volume of the heat radiating foam sheet is, for example, a foam composition described later. It is possible to calculate by subtracting the volume of the additive (foaming agent) that decomposes and disappears during foaming from the total volume of the product. Moreover, the volume of the above-described components (A), (B), and (C) can be calculated from the mass of each component to be blended. For example, the density of each component at 23 ° C. is the mass of each component. Can be calculated by multiplying by.

[Foaming agent]
The heat dissipating foam sheet is foamed with a foaming agent, and is usually obtained by foaming a foamable composition containing a foaming agent in addition to the components (A) to (C). Moreover, it is preferable to foam the crosslinked foamable composition. A thermal decomposition type foaming agent is preferable as the foaming agent. Specific examples of the pyrolytic foaming agent include organic or inorganic chemical foaming agents having a decomposition temperature of about 140 ° C to 270 ° C.
Examples of organic foaming agents include azodicarbonamide, azodicarboxylic acid metal salts (such as barium azodicarboxylate), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, Examples thereof include hydrazine derivatives such as hydrazodicarbonamide, 4,4′-oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide, and semicarbazide compounds such as toluenesulfonyl semicarbazide.
Examples of the inorganic foaming agent include ammonium acid, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate, and the like.
Among these, azo compounds and nitroso compounds are preferable from the viewpoint of obtaining fine bubbles, and from the viewpoints of economy and safety, and azodicarbonamide, azobisisobutyronitrile, N, N′-dinitrosopentamethylene. Tetramine is more preferred, and azodicarbonamide is particularly preferred. These pyrolytic foaming agents can be used alone or in combination of two or more.
As for the compounding quantity of a thermal decomposition type foaming agent, 1-30 mass parts is preferable with respect to 100 mass parts of elastomers (A). By setting it as such a compounding quantity, it can foam appropriately, without the bubble of a thermal radiation foam sheet bursting. Moreover, when the compounding quantity of a thermal decomposition type foaming agent is increased, an apparent density will become low and it is possible to improve a softness | flexibility. Therefore, as for the compounding quantity of a thermal decomposition type foaming agent, 5-25 mass parts is more preferable, and 10-25 mass parts is further more preferable.

[Other ingredients]
The heat dissipation foam sheet may contain components other than those described above. Examples of such components include various additives usually used for foams. Examples of additives include foaming aids, lubricants, shrinkage inhibitors, cell nucleating agents, crystal nucleating agents, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, anti-aging agents, and fillers other than the above fillers. Agents, reinforcing agents, flame retardants, flame retardant aids, antistatic agents, surfactants, vulcanizing agents, surface treatment agents, softening agents and the like. Such additives can be used alone or in combination of two or more. The amount of these additives can be selected as appropriate as long as the effects of the present invention are not impaired, and the amount used for ordinary foams can be employed.
Among the additives described above, it is preferable to use an antioxidant in the heat dissipation foam sheet. Examples of the antioxidant include phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants, amine antioxidants, etc. Among them, phenolic antioxidants are preferable. An antioxidant may be used independently and 2 or more types may be used together.
0.03-10 mass parts is preferable with respect to 100 mass parts of elastomers (A), and, as for content of antioxidant, 0.05-5 mass parts is more preferable.

(Thickness of heat dissipation foam sheet)
The thickness of the heat dissipating foam sheet is preferably 0.05 to 1 mm. By setting the thickness of the heat dissipating foam sheet to be 0.05 mm or more, the mechanical strength of the heat dissipating foam sheet is increased, and tearing is prevented. Moreover, it becomes easy to arrange | position inside a small electronic device because it shall be 1 mm or less. The thickness of the heat dissipating foam sheet is more preferably 0.05 to 0.8 mm, and further preferably 0.1 to 0.5 mm. Since the heat dissipation foamed sheet of the present invention has good flexibility and thermal conductivity, it has high heat dissipation, shock absorption, and sealing properties even when it is thin.

(Apparent density)
It is preferable that the heat dissipation foamed sheet has an apparent density of 0.5 to 2.0 g / cm ³ .
By making the apparent density within such a range, it becomes easy to improve the flexibility and thermal conductivity of the heat dissipating foam sheet. The apparent density is more preferably 0.6 to 1.2 g / cm ³ and further preferably 0.7 to 0.95 g / cm ³ from the viewpoint of improving the flexibility and thermal conductivity in a balanced manner. .

(Compressive strength)
The heat dissipating foam sheet preferably has a 25% compressive strength of 15 to 150 kPa. By setting the 25% compressive strength within the above range, the flexibility of the heat dissipating foam sheet is ensured. In order to improve the flexibility and thermal conductivity in a good balance, the 25% compressive strength is more preferably 20 to 100 kPa, and further preferably 20 to 70 kPa.

(Thermal conductivity)
The thermal conductivity of the heat dissipating foam sheet is preferably 0.70 to 3.0 W / m · K. Good heat dissipation can be obtained when the thermal conductivity is 0.70 W / m · K or more.
From the viewpoint of heat dissipation and ease of manufacture of the heat dissipation foam sheet, the thermal conductivity is more preferably 0.85 to 2.5 W / m · K, and further preferably 1.2 to 2.3 W / m · K. In addition, thermal conductivity can be measured according to the method as described in the Example mentioned later.

<Method for producing heat dissipation foam sheet>
As a manufacturing method of the heat dissipation foam sheet of the present invention, a foamable composition in which at least a plate filler (B) and a spherical filler (C) are blended with the elastomer (A) is foamed to obtain a heat dissipation foam sheet. Is mentioned. Hereinafter, this production method will be described in more detail.

  In this production method, the foamable composition supplies, for example, an elastomer (A), a plate-like filler (B), a spherical filler (C), and, if necessary, a foaming agent and other optional components to the extruder. Then, it may be melt-kneaded and formed into a sheet by extrusion from an extruder. Alternatively, the elastomer (A), the plate-like filler (B), the spherical filler (C), and further, if necessary, the foaming agent and other optional components are continuously kneaded using a calendar, conveyor belt casting, or the like. What is necessary is just to make a foamable composition into a sheet form by conveying. Also, the foamable composition can be made into a sheet by pressing an elastomer (A), a plate-like filler (B), a spherical filler (C), and a kneaded foaming agent and other optional components as necessary. Good.

The method for foaming the foamable composition is not particularly limited, but as described above, foaming is preferably performed with a foaming agent such as a pyrolytic foaming agent. When foaming with a pyrolytic foaming agent, the foamable composition may be heated at a temperature higher than the decomposition temperature of the pyrolytic foaming agent. The heating temperature is, for example, 200 to 400 ° C, preferably 220 to 300 ° C. Moreover, it is good to perform a foaming process with respect to the foamable composition shape | molded in the sheet form as mentioned above.
The method for decomposing and foaming the pyrolytic foaming agent is not particularly limited. For example, the foamable composition is heated with hot air, the infrared heating method, the salt bath heating method, or the oil bath heating method. These may be used, and these may be used in combination.

In this production method, it is preferable to crosslink the foamable composition before foaming. The crosslinking treatment may be performed after the foamable composition is formed into a sheet shape. Examples of the method for crosslinking the foamable composition include, for example, a method of irradiating the foamable composition with ionizing radiation such as electron beam, α-ray, β-ray, and γ-ray, and an organic peroxide previously applied to the foamable composition. In addition, a method in which a sulfur-based compound such as sulfur is blended, the foamable composition is heated to decompose the organic peroxide, or vulcanized with a sulfur compound is included. Good. In these, the method of irradiating ionizing radiation is preferable, and it is more preferable to use an electron beam especially. The irradiation amount of ionizing radiation is, for example, 0.5 to 15 Mrad, preferably 1 to 5 Mrad.
Further, the heat dissipation foam sheet may be stretched after foaming or while foaming. In addition, the manufacturing method of a thermal radiation foam sheet is not limited to the said method, You may manufacture by another method.

<How to use heat dissipation foam sheet>
Although the heat-radiation foam sheet of this invention is not specifically limited, It is preferable to use it for an electronic device use. The electronic device is preferably a mobile electronic device such as a mobile phone such as a smartphone, a tablet terminal, electronic paper, a notebook PC, a video camera, or a digital camera.
The heat dissipating foam sheet is disposed in the vicinity of the heat source inside the electronic device, and is used as a heat dissipating material that diffuses or dissipates heat generated from the heat source. Further, it can also be suitably used as an impact absorbing material for absorbing impacts and vibrations, and as a sealing material for filling a gap to prevent dust and waterproofing. Since the heat dissipating foam sheet is highly flexible and thin, it can be appropriately disposed in a narrow space.

  The heat dissipating foam sheet may be disposed in a space between the various electronic components and the heat sink, for example, inside the electric device. The heat dissipating foam sheet arranged in this way can release heat generated in various electronic components to the heat sink. The heat source is an electronic component that generates heat when driven or used, and specifically includes a display device such as a CPU, a battery, a power amplifier, a liquid crystal panel, and an organic EL panel. In addition, examples of the heat sink include a metal member such as iron or stainless steel, a material having high thermal conductivity such as graphite, or a composite or laminate of these materials, and may constitute a housing of an electronic device.

<Adhesive tape>
Moreover, you may use for the adhesive tape which uses the thermal radiation foam sheet of this invention as a base material. The pressure-sensitive adhesive tape includes, for example, a heat dissipation foam sheet and a pressure-sensitive adhesive layer provided on at least one surface of the heat dissipation foam sheet, but may be a double-sided pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on both sides.
The thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape is preferably 5 to 200 μm. The thickness of the pressure-sensitive adhesive layer is more preferably 7 to 150 μm, still more preferably 10 to 100 μm. The thickness of the structure fixed using the adhesive tape can be made thin as the thickness of an adhesive layer is the range of 5-200 micrometers.
There is no restriction | limiting in particular as an adhesive used for an adhesive layer, For example, an acrylic adhesive, a urethane type adhesive, a rubber-type adhesive etc. can be used. Further, a release sheet such as a release paper may be further bonded on the pressure-sensitive adhesive layer.

Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In addition, the measuring method and evaluation method of each physical property in this invention are as follows.
[Average particle diameter of plate-like filler (B) and spherical filler (C)]
Using a laser diffraction / scattering particle size distribution measuring device (HELOS / BFM, manufactured by Sympatec GmbH), the particle size distribution was measured by a conventional method, and the average value of the average particle size when measured five times was defined as the average particle size. .
[Apparent density]
It measured based on JISK7222.
[25% compressive strength]
The 25% compressive strength in the thickness direction of the heat dissipating foam sheet was measured in accordance with JIS K6767-7.2.3 (JIS2009).
[Heat dissipation test]
Samples were prepared by cutting the heat-dissipating foamed sheets obtained in each Example and Comparative Example into 2 cm squares and stacking them until the thickness reached 1 cm or more. About the sample, the thermal conductivity was measured at 23 degreeC by the hot disk method using "TPS-1500" by Kyoto Electronics Industry Co., Ltd.

In the following Examples and Comparative Examples, the volume% was calculated with the volume obtained by subtracting the volume of the foaming agent from the total amount of the foamable composition as the volume of the total foam. Moreover, volume% was computed from the mass part and density of each component.
[Example 1]
60 parts by mass of ethylene propylene diene rubber (Mitsui Chemicals, trade name: EMB-EPT4021), 40 parts by mass of ethylene propylene diene rubber (Mitsui Chemicals, trade name: PX-68), and pyrolytic foaming 17 parts by mass of azodicarbonamide as an agent and boron nitride (PTX-25S, manufactured by Momentive Performance Materials, average particle size: 25 μm, thermal conductivity: 250 W / m · K) 180 as a plate-like filler (B) 180 parts by mass of magnesium oxide (RF-50-SC, manufactured by Ube Materials Co., Ltd., average particle size: 50 μm, thermal conductivity: 50 W / m · K) as a spherical filler (C) and antioxidant The foamable composition obtained by melt-kneading 0.1 parts by mass of a phenolic antioxidant as an agent at 130 ° C. with a plastmill is pressed. Thus, a long sheet having a thickness of 0.3 mm was formed.
Next, the foamable composition was crosslinked by irradiating an electron beam with an acceleration voltage of 500 kV for 1.5 Mrad on both surfaces of the long sheet-like foamable composition.
Thereafter, the foamable composition was continuously fed into a foaming furnace maintained at 250 ° C. with hot air and an infrared heater, and heated to foam to obtain a heat radiating foam sheet. The heat dissipating foam sheet had an apparent density of 0.82 g / cm ³ and a thickness of 0.28 mm. The total amount of elastomer was 50% by volume, the plate-like filler (B) was 30% by volume, and the spherical filler (C) was 20% by volume on the basis of the total volume of the heat dissipating foam sheet.
About this heat dissipation foamed sheet, 25% compressive strength was measured to evaluate flexibility, and a heat dissipation test at 50% compression was performed to evaluate heat dissipation performance.

[Example 2]
Boron nitride (PTX-25S, manufactured by Momentive Performance Materials, average particle size: 25 μm, thermal conductivity: 250 W / m · K) 180 parts by mass, magnesium oxide (RF-50-SC, Ube) This was carried out in the same manner as in Example 1 except that 180 parts by mass of Materials Co., Ltd., average particle size: 50 μm, thermal conductivity: 50 W / m · K) was changed to 270 parts by mass. The total volume of the elastomer was 55% by volume, the plate-like filler (B) was 15% by volume, and the spherical filler (C) was 30% by volume based on the total volume of the heat dissipating foam sheet.

[Comparative Example 1]
Magnesium oxide (RF-50-SC, manufactured by Ube Materials Co., Ltd., average particle size: 50 μm, thermal conductivity: 50 W / m · K) 180 parts by mass, 300 parts by mass, boron nitride (PTX-25S, Momentive) -The performance was carried out in the same manner as in Example 1 except that the performance materials, average particle size: 25 μm, and thermal conductivity: 250 W / m · K) were used without being used. Table 1 shows various properties of the foam sheet and evaluation results. The total amount of elastomer was 65% by volume and the spherical filler (C) was 35% by volume on the basis of the total volume of the heat dissipating foam sheet.

[Comparative Example 2]
200 parts by mass of boron nitride (PTX-25S, manufactured by Momentive Performance Materials, average particle size: 25 μm, thermal conductivity: 250 W / m · K), 200 parts by mass, magnesium oxide (RF-50-SC, Ube Material) The product was manufactured in the same manner as in Example 1 except that 180 parts by mass was changed to 50 parts by mass, average particle diameter: 50 μm, thermal conductivity: 50 W / m · K. The total elastomer was 57% by volume, the plate-like filler (B) was 37% by volume, and the spherical filler (C) was 6% by volume on the basis of the total volume of the heat dissipating foam sheet.

  In Examples 1 and 2 described above, the thermal conductivity is increased by adding the elastomer (A), the plate-like filler (B), and the spherical filler (C) to the heat-dissipating foam sheet at a predetermined volume%. The heat dissipation was excellent. Also, the compressive strength was a good value and the flexibility was excellent. On the other hand, since Comparative Example 1 did not contain one of the plate-like filler (B) and the spherical filler (C), the thermal conductivity was low and the heat dissipation was not excellent. Moreover, in Comparative Example 2, since the plate-like filler (B) was added too much, abnormal foaming occurred and the heat dissipation foam sheet could not be formed appropriately.

Claims (9)

An elastomer (A), a plate-like filler (B) dispersed in the elastomer (A), and a spherical filler (C);
A heat-dissipating foam sheet in which the elastomer (A) is 40 to 70% by volume, the plate-like filler (B) is 10 to 35% by volume, and the spherical filler (C) is 15 to 35% by volume on the basis of the total volume of the heat-dissipating foam sheet.   Each of the plate filler (B) and the spherical filler (C) is at least one selected from the group consisting of silica, aluminum oxide, magnesium oxide, boron nitride, talc, aluminum nitride, carbon-based filler, and conductive metal particles. The heat dissipating foam sheet according to claim 1.   The heat dissipation foamed sheet according to claim 1 or 2, wherein the plate-like filler (B) has an average particle size of 5 to 100 µm, and the spherical filler (C) has an average particle size of 10 to 150 µm.   The heat dissipation foamed sheet according to any one of claims 1 to 3, wherein the spherical filler (C) has an average particle size larger than that of the plate-like filler (B).   The heat dissipation foamed sheet according to any one of claims 1 to 4, wherein the volume percentage of the plate-like filler (B) is higher than the volume percentage of the spherical filler (C).   The heat dissipating foam sheet according to any one of claims 1 to 5, wherein the heat dissipating foam sheet is foamed with a pyrolytic foaming agent.   Thickness is 0.05-1 mm, The thermal radiation foam sheet of any one of Claims 1-6. The heat dissipation foam sheet according to any one of claims 1 to 7, which has an apparent density of 0.5 to 2.0 g / cm ³ .   A pressure-sensitive adhesive tape comprising: the heat dissipation foam sheet according to any one of claims 1 to 8; and an adhesive layer provided on at least one surface of the heat dissipation foam sheet.