JP6684405B2 - Thermal conductive sheet - Google Patents
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- 239000002245 particle Substances 0.000 claims description 73
- 239000011231 conductive filler Substances 0.000 claims description 50
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical group O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 40
- 238000012360 testing method Methods 0.000 claims description 38
- 229910001593 boehmite Inorganic materials 0.000 claims description 36
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 36
- 239000011159 matrix material Substances 0.000 claims description 33
- 238000011156 evaluation Methods 0.000 claims description 18
- 229920001296 polysiloxane Polymers 0.000 claims description 15
- 229920000642 polymer Polymers 0.000 claims description 11
- 230000004580 weight loss Effects 0.000 claims description 11
- 238000006482 condensation reaction Methods 0.000 claims description 8
- 238000002485 combustion reaction Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 description 17
- 230000001965 increasing effect Effects 0.000 description 16
- 239000003063 flame retardant Substances 0.000 description 15
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 14
- 238000001723 curing Methods 0.000 description 11
- 239000003795 chemical substances by application Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 6
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229920001971 elastomer Polymers 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 3
- 239000000347 magnesium hydroxide Substances 0.000 description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 239000011344 liquid material Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 125000003342 alkenyl group Chemical group 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 239000007822 coupling agent Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000012767 functional filler Substances 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 1
- 229920006136 organohydrogenpolysiloxane Polymers 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
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Description
本発明は、発熱体と放熱体の間に配置して用いられる熱伝導性シートに関する。 The present invention relates to a heat conductive sheet used by being arranged between a heating element and a radiator.
電子機器では生じる熱を放熱するためにヒートシンクなどの放熱体が用いられており、この放熱体への熱の伝達効率を高める目的で発熱体と放熱体の間に熱伝導性シートを配置することがある。この熱伝導性シートに関する技術が例えば特開２０１４−４１９５３号公報（特許文献１）に記載されている。 Heat sinks and other heat sinks are used in electronic devices to dissipate the generated heat.A heat conductive sheet should be placed between the heat sinks to increase the efficiency of heat transfer to the heat sink. There is. A technique relating to this heat conductive sheet is described in, for example, JP-A-2014-41953 (Patent Document 1).
熱伝導性シートは、電子機器に組み込まれて用いられるため、火災に対する安全性にも配慮することが要求され、難燃性を備えていることが望まれる。しかしながら、熱伝導性シートは、熱伝導性充填材が高分子材からなるマトリクスに含有されており、熱伝導性を有しながらも柔らかい性質を備えたものである。そのため、難燃性を付与するために難燃剤を添加すると熱伝導性シートの柔軟性が損なわれることから、その柔軟性を保つためには相対的に熱伝導性充填材の含有量を減らす必要があり、熱伝導性充填材の含有量を減らせば熱伝導性が低下するという不具合が生じることになる。そこで、難燃剤が熱伝導性を有していれば、熱伝導性充填材の配合量を必要以上に減らさないで済むことから、難燃剤にはある程度の熱伝導性を備える水酸化アルミニウムのような金属水酸化物の利用が検討された。 Since the heat conductive sheet is used by being incorporated in an electronic device, it is required to consider safety against fire and it is desired that it has flame retardancy. However, the heat conductive sheet contains a heat conductive filler in a matrix made of a polymer material, and has a soft property while having heat conductivity. Therefore, when a flame retardant is added to impart flame retardancy, the flexibility of the heat conductive sheet is impaired, so it is necessary to relatively reduce the content of the heat conductive filler in order to maintain the flexibility. Therefore, if the content of the thermally conductive filler is reduced, the thermal conductivity will be deteriorated. Therefore, if the flame retardant has thermal conductivity, it is not necessary to reduce the amount of the thermally conductive filler compounded more than necessary. The use of various metal hydroxides was investigated.
そうした一方で、近年では電子機器の高性能化に伴い、放熱対策が求められる電子部品も多様化しており、熱伝導性シートに対しても従来よりも高い耐熱性が求められる場合が生じてきた。例えば、パワー半導体に対する放熱対策としては、２００℃の耐熱性を備えた熱伝導性シートが求められおり、１５０℃の耐熱性を備える従来の熱伝導性シートでは耐熱性が不十分である。 On the other hand, in recent years, along with the high performance of electronic devices, electronic parts that require heat dissipation measures are also diversified, and there are cases in which heat resistance of heat conductive sheets is also required to be higher than before. . For example, as a heat radiation measure for a power semiconductor, a heat conductive sheet having a heat resistance of 200 ° C. is required, and a conventional heat conductive sheet having a heat resistance of 150 ° C. has insufficient heat resistance.
こうした耐熱性が要求される熱伝導性シートにおいて、難燃剤として水酸化アルミニウムを用いていたのでは、約１８０℃から脱水反応が起こるため、２００℃以上になるパワー半導体用の熱伝導性シートには用いることができない。この問題に対して、約３３０℃から脱水反応が起こる水酸化マグネシウムを用いることが考えられるが、水酸化マグネシウムは、耐熱性試験後に熱伝導性シートが硬くなるという不具合があることがわかってきた。しがたって、２００℃の耐熱性と、高い難燃性とを備えた熱伝導性シートを得ることは困難であった。 In such a heat conductive sheet that requires heat resistance, if aluminum hydroxide is used as a flame retardant, a dehydration reaction occurs from about 180 ° C. Cannot be used. To solve this problem, it is possible to use magnesium hydroxide, which causes a dehydration reaction at about 330 ° C. However, it has been found that magnesium hydroxide has a problem that the heat conductive sheet becomes hard after the heat resistance test. . Therefore, it was difficult to obtain a heat conductive sheet having heat resistance of 200 ° C. and high flame retardancy.
本発明は、上記課題を解決するためになされたものである。すなわち、柔軟性と熱伝導性とを維持しながら、耐熱性と難燃性とを備えた熱伝導性シートを提供することを目的とする。 The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide a heat conductive sheet having heat resistance and flame resistance while maintaining flexibility and heat conductivity.
上記の課題を解決するために、本発明は次の構成を有する。
マトリクス１００質量部に対して、ベーマイト１７５〜２７０質量部と、２０Ｗ／ｍ・Ｋ以上の熱伝導率である熱伝導性充填材５０〜３００質量部と、を含み、この熱伝導性充填材中に粒径が５μｍ以下の熱伝導性充填材粒子を３０質量部以上含む熱伝導性シートである。
In order to solve the above problems, the present invention has the following configurations.
Includes 175 to 270 parts by mass of boehmite and 50 to 300 parts by mass of the thermally conductive filler having a thermal conductivity of 20 W / m · K or more with respect to 100 parts by mass of the matrix. Is a thermally conductive sheet containing 30 parts by mass or more of thermally conductive filler particles having a particle size of 5 μm or less.
マトリクス１００質量部に対して、ベーマイト１７５〜２７０質量部と、２０Ｗ／ｍ・Ｋ以上の熱伝導率である熱伝導性充填材５０〜３００質量部と、を含み、この熱伝導性充填材中に粒径が５μｍ以下の熱伝導性充填材粒子を３０質量部以上含むため、柔軟性と熱伝導性とを有することに加え、耐熱性と難燃性の双方にも優れた熱伝導性シートとすることができる。 Includes 175 to 270 parts by mass of boehmite and 50 to 300 parts by mass of the thermally conductive filler having a thermal conductivity of 20 W / m · K or more with respect to 100 parts by mass of the matrix. Since it contains 30 parts by mass or more of thermally conductive filler particles having a particle size of 5 μm or less, it has flexibility and thermal conductivity, and also has excellent heat resistance and flame retardancy. Can be
すなわち、熱伝導性シートに難燃性を付与するためには難燃剤を配合することが必要となるのに対し、所望の柔軟性を保持しながら難燃剤を配合すると相対的に熱伝導性充填材の配合量が減少し、熱伝導性が悪化する。そのため、配合する熱伝導性充填材の一部を難燃剤に置き換えただけでは所望の難燃性および熱伝導性は得られない。こうした課題がある中で、熱伝導性充填材の粒径に着目し、この粒径が５μｍ以下となる熱伝導性充填材（但し、熱伝導率が２０Ｗ／ｍ・Ｋ以上）を全熱伝導性充填材５０〜３００質量部のうち、３０質量部以上配合することにより所望の難燃性と熱伝導性が得られることを見い出したのである。 That is, in order to impart flame retardancy to the heat conductive sheet, it is necessary to blend a flame retardant, while blending a flame retardant while maintaining desired flexibility results in relatively thermal conductive filling. The compounding amount of the material decreases, and the thermal conductivity deteriorates. Therefore, the desired flame retardancy and thermal conductivity cannot be obtained simply by replacing a part of the thermally conductive filler to be blended with the flame retardant. In view of these problems, pay attention to the particle size of the heat conductive filler, and use the heat conductive filler with a particle size of 5 μm or less (however, the thermal conductivity is 20 W / m · K or more) for total heat conduction. It was found that the desired flame retardancy and thermal conductivity can be obtained by blending 30 parts by mass or more of 50 to 300 parts by mass of the functional filler.
マトリクスには、５％重量減少温度が４００℃以上の高分子を用いることができる。
マトリクスに５％重量減少温度が４００℃以上の高分子を用いることで耐熱性を向上させることができ、２００℃の環境においても物性の劣化を確実に抑制可能な熱伝導性シートが得られる。
また、マトリクスには、縮合反応型シリコーンを用いることができる。マトリクスに縮合反応型シリコーンを用いたため、熱伝導性シートの耐熱性を高めることができる。
A polymer having a 5% weight loss temperature of 400 ° C. or higher can be used for the matrix.
By using a polymer having a 5% weight loss temperature of 400 ° C. or higher for the matrix, heat resistance can be improved, and a thermally conductive sheet capable of reliably suppressing deterioration of physical properties even in an environment of 200 ° C. can be obtained.
Further, condensation reaction type silicone can be used for the matrix. Since the condensation reaction type silicone is used for the matrix, the heat resistance of the heat conductive sheet can be improved.
熱伝導性充填材には酸化アルミニウムを用いることができる。熱伝導性充填材に酸化アルミニウムを用いたため、熱伝導性を高めつつ、高温での安定性に優れた熱伝導性シートを得ることができる。 Aluminum oxide can be used as the heat conductive filler. Since aluminum oxide is used as the heat conductive filler, it is possible to obtain a heat conductive sheet which is excellent in stability at high temperature while enhancing heat conductivity.
日本工業規格であるＪＩＳ Ｋ６２５３のタイプＥの硬度計によって測定されるＥ硬度が５〜９０である熱伝導性シートとすることができる。
日本工業規格であるＪＩＳ Ｋ６２５３のタイプＥの硬度計によって測定されるＥ硬度が５〜９０であるため、柔軟性に優れ、発熱体と放熱体との間に密着させて、効果的に熱伝導を促すことができる。
A heat conductive sheet having an E hardness of 5 to 90 as measured by a type E hardness meter of JIS K6253 which is a Japanese industrial standard can be used.
Since the E hardness measured by the Japanese Industrial Standard JIS K6253 type E hardness meter is 5 to 90, it is excellent in flexibility and can be closely contacted between the heat generating element and the heat radiating element to effectively conduct heat. Can be encouraged.
前記ベーマイトの平均粒径を５μｍ以下とすることができ、好ましくは平均粒径を２μｍ以下とすることができる。ベーマイトの平均粒径を５μｍ以下としたため、粒径が５μｍ以下の熱伝導性充填材を所定量含むことと相まって、熱伝導性充填材の充填性を高め、効果的に熱伝導性と難燃性を高めることができる。 The average particle size of the boehmite can be 5 μm or less, and preferably 2 μm or less. Since the average particle size of boehmite is set to 5 μm or less, the amount of the heat conductive filler having a particle size of 5 μm or less is included, so that the filling property of the heat conductive filler is increased, and the heat conductivity and flame retardancy are effectively increased. You can improve your sex.
米国アンダー・ライターズ・ラボラトリーズ・インク（Ｕｎｄｅｒ Ｗｒｉｔｅｒｓ Ｌａｂｏｒａｔｏｒｉｅｓ Ｉｎｃ）によって制定された燃焼試験（ＵＬ９４）による難燃性の評価でＶ−０を備える熱伝導性シートとすることができる。
米国アンダー・ライターズ・ラボラトリーズ・インクによって制定された燃焼試験（ＵＬ９４）による難燃性の評価でＶ−０を備えるため、難燃性に優れた熱伝導性シートである。
It can be a heat conductive sheet provided with V-0 by flame retardancy evaluation by a combustion test (UL94) established by Under Writers Laboratories Inc. in the United States.
It is a heat conductive sheet having excellent flame retardancy because it has V-0 according to the flame retardancy evaluation by the combustion test (UL94) established by Underwriters Laboratories, Inc. in the United States.
２００℃の雰囲気中で１０００時間放置した後の屈曲強度の変化が７５〜１５０％以内である熱伝導性シートとすることができる。
２００℃の雰囲気中で１０００時間放置した後の屈曲強度の変化が７５〜１５０％以内であるため、２００℃の雰囲気下でも変化を起こし難い耐熱性に優れた熱伝導性シートである。
The heat conductive sheet can have a change in bending strength of 75 to 150% after being left in an atmosphere of 200 ° C. for 1000 hours.
Since the change in flexural strength after being left for 1000 hours in an atmosphere of 200 ° C. is within 75 to 150%, it is a heat conductive sheet excellent in heat resistance that hardly changes even in an atmosphere of 200 ° C.
本発明によれば、柔軟性と熱伝導性を有し、かつ耐熱性と難燃性とを備えた熱伝導性シートである。 According to the present invention, the heat conductive sheet has flexibility and heat conductivity, and also has heat resistance and flame retardancy.
本発明の熱伝導性シートについてさらに詳しく説明する。本発明の熱伝導性シートは、マトリクスとべーマイトと熱伝導性充填材とを含んで構成される。 The heat conductive sheet of the present invention will be described in more detail. The heat conductive sheet of the present invention comprises a matrix, boehmite, and a heat conductive filler.
マトリクス： マトリクスは、樹脂やゴム等の高分子であり、好ましくは主剤と硬化剤のような混合系からなる液状の高分子組成物を硬化して形成したものとすることができる。したがってこの高分子組成物は、例えば、未架橋ゴムと架橋剤を含むものであったり、架橋剤を含む未架橋ゴムと架橋促進剤を含むものであったりすることができる。また、その硬化反応は常温硬化であっても熱硬化であっても良い。高分子マトリクスがシリコーンゴムであれば、アルケニル基含有オルガノポリシロキサンとオルガノハイドロジェンポリシロキサンなどが例示できる。 Matrix: The matrix is a polymer such as resin or rubber, and can be preferably formed by curing a liquid polymer composition including a mixed system such as a main agent and a curing agent. Therefore, this polymer composition can contain, for example, an uncrosslinked rubber and a crosslinking agent, or can contain an uncrosslinked rubber containing a crosslinking agent and a crosslinking accelerator. The curing reaction may be room temperature curing or heat curing. If the polymer matrix is silicone rubber, alkenyl group-containing organopolysiloxane and organohydrogenpolysiloxane can be exemplified.
このようなマトリクスの中でも、硬化後のマトリクスの５％重量減少温度が４００℃以上である高分子を用いることが好ましい。これらの高分子には、シリコーンやポリイミド、シリコーン変性ポリイミドを例示することができる。そして、これらの材質の中ではシリコーンを用いることが好ましい。シリコーンは柔軟性と耐熱性を併せ持つため、熱伝導性シートの柔軟性を高めて熱抵抗を低くすることができるからである。また、シリコーンの中でも、縮合反応型のシリコーンを用いることがより好ましい。縮合反応型のシリコーンは、付加反応型のシリコーンと比較して、硬化物の分子量を高めやすいからである。分子量を高めることで耐熱性を向上させることができ、２００℃の環境においても物性の劣化を確実に抑制することができる。また、５％重量減少温度の上限は特に限定しないが、高分子組成物の硬化物では５００℃程度が上限となる。 Among such matrices, it is preferable to use a polymer in which the 5% weight loss temperature of the matrix after curing is 400 ° C. or higher. Examples of these polymers include silicone, polyimide, and silicone-modified polyimide. And it is preferable to use silicone among these materials. Since silicone has both flexibility and heat resistance, the flexibility of the heat conductive sheet can be increased and the heat resistance can be lowered. Further, among silicones, it is more preferable to use condensation reaction type silicone. This is because the condensation reaction type silicone is more likely to increase the molecular weight of the cured product than the addition reaction type silicone. By increasing the molecular weight, heat resistance can be improved, and deterioration of physical properties can be reliably suppressed even in an environment of 200 ° C. Although the upper limit of the 5% weight loss temperature is not particularly limited, the upper limit is about 500 ° C. in the cured product of the polymer composition.
熱伝導性充填材： 熱伝導性充填材は、マトリクスに熱伝導性を付与する材料である。
熱伝導性充填材には、例えば、金属酸化物、金属窒化物、金属炭化物、炭素などの球状や不定形の粉末が挙げられる。金属酸化物としては、酸化アルミニウム、酸化マグネシウム、酸化亜鉛、石英など、金属窒化物としては、窒化ホウ素、及び窒化アルミニウムなどを例示することができる。また、金属炭化物としては、炭化ケイ素が挙げられる。炭素としては黒鉛化炭素粉末が挙げられる。これらの熱伝導性充填材の中でも、酸化アルミニウムを用いることが好ましい。熱伝導率が高く、球状のものが入手しやすく、さらに高温での安定性が高いため２００℃の環境においても劣化するおそれがないためである。
Thermally conductive filler: The thermally conductive filler is a material that imparts thermal conductivity to the matrix.
Examples of the heat conductive filler include spherical or amorphous powders of metal oxides, metal nitrides, metal carbides, carbon and the like. Examples of the metal oxide include aluminum oxide, magnesium oxide, zinc oxide, and quartz, and examples of the metal nitride include boron nitride and aluminum nitride. In addition, examples of the metal carbide include silicon carbide. Examples of carbon include graphitized carbon powder. Among these heat conductive fillers, aluminum oxide is preferably used. This is because spherical particles have high thermal conductivity, are easily available, and have high stability at high temperatures, so that they do not deteriorate even in an environment of 200 ° C.
このような熱伝導性充填材は、アスペクト比が２以下であることが好ましい。アスペクト比が２を超えると、粘度が上昇しやすく高充填し難いためである。こうした理由から、熱伝導性充填材の形状は球状であることが好ましい。 Such a heat conductive filler preferably has an aspect ratio of 2 or less. This is because if the aspect ratio exceeds 2, the viscosity tends to increase and high filling is difficult. For these reasons, the shape of the heat conductive filler is preferably spherical.
用いる熱伝導性充填材の熱伝導率は２０Ｗ／ｍ・Ｋ以上である。熱伝導性充填材とともに配合するベーマイトの熱伝導率が８Ｗ／ｍ・Ｋ程度とやや低いため、熱伝導率の高い熱伝導性充填材を配合しないと、満足する熱伝導性を有する熱伝導性シートが得られないからである。 The thermal conductivity of the thermally conductive filler used is 20 W / m · K or more. The thermal conductivity of boehmite compounded with the thermally conductive filler is rather low at about 8 W / mK, so if the thermally conductive filler with high thermal conductivity is not blended, it has satisfactory thermal conductivity. This is because the seat cannot be obtained.
熱伝導性充填材は、マトリクス１００質量部に対して５０〜３００質量部の範囲で添加するが、１７５〜２２５質量部の範囲で添加することが好ましい。５０質量部未満の場合には熱伝導性が悪くなる。一方、３００質量部を超えても、熱伝導性を高める効果が上がり難くなる一方で、柔軟性が乏しくなる。そして１７５〜２２５質量部の範囲では、熱伝導性と難燃性に優れ、またマトリクスが硬化する前の混合組成物の状態での粘度が好適である。 The heat conductive filler is added in the range of 50 to 300 parts by mass, preferably in the range of 175 to 225 parts by mass, with respect to 100 parts by mass of the matrix. If it is less than 50 parts by mass, the thermal conductivity will be poor. On the other hand, if the amount exceeds 300 parts by mass, the effect of increasing the thermal conductivity becomes difficult to increase, but the flexibility becomes poor. In the range of 175 to 225 parts by mass, the thermal conductivity and flame retardancy are excellent, and the viscosity of the mixed composition before the matrix is cured is suitable.
こうした熱伝導性充填材の中で、粒径が５μｍ以下の粒子を３０質量部以上含むことが必要である。粒径が５μｍ以下の粒子を３０質量部以上含むことで難燃性を高める効果があるからである。
また、含有する熱伝導性充填材の平均粒径は８０μｍ以下が好ましい。８０μｍを超えると安定した熱伝導性が得られないおそれがある。平均粒径の下限は難燃性の観点からは制限されないが、０．５μｍ以上であることが好ましい。平均粒径が０．５μｍ未満の場合は、比表面積が大きくなるためマトリクスを硬化させる前の混合組成物の粘度が上昇し、取扱いがし難くなるからである。熱伝導性充填材の平均粒径は、レーザ回折散乱法（ＪＩＳ Ｒ１６２９）により測定した粒度分布の体積平均粒径で示すことができる。
It is necessary to include 30 parts by mass or more of particles having a particle size of 5 μm or less in such a heat conductive filler. This is because the inclusion of 30 parts by mass or more of particles having a particle size of 5 μm or less has the effect of increasing flame retardancy.
The average particle size of the heat conductive filler contained is preferably 80 μm or less. If it exceeds 80 μm, stable thermal conductivity may not be obtained. The lower limit of the average particle size is not limited from the viewpoint of flame retardancy, but it is preferably 0.5 μm or more. When the average particle size is less than 0.5 μm, the specific surface area becomes large and the viscosity of the mixed composition before curing the matrix increases, which makes it difficult to handle. The average particle size of the heat conductive filler can be indicated by the volume average particle size of the particle size distribution measured by the laser diffraction scattering method (JIS R1629).
ベーマイト： ベーマイトは、ＡｌＯ（ＯＨ）またはＡｌ２Ｏ３・Ｈ２Ｏで表されるアルミナ水和物であり、熱伝導性シートに難燃性を付与するとともに、熱伝導性充填材ほどではないが熱伝導性を与える物質である。
ベーマイトの含有量は、マトリクス１００質量部に対して１７５〜２７０質量部である。１７５質量部未満の場合には難燃性が悪化する。一方、２７０質量部を超えると、相対的に熱伝導性充填材の含有量が少なくなるため熱伝導性が悪化する。１７５〜２７０質量部であると、優れた難燃性を発揮することができる。また、難燃剤として水酸化アルミニウムや水酸化マグネシウムを用いたときに生じるような熱履歴を受けた後の硬質化を起こさない。
Boehmite: Boehmite is an alumina hydrate represented by AlO (OH) or Al 2 O 3 .H 2 O, which imparts flame retardancy to a heat conductive sheet and is not as good as a heat conductive filler. Is a substance that imparts thermal conductivity.
The content of boehmite is 175 to 270 parts by mass with respect to 100 parts by mass of the matrix. If it is less than 175 parts by mass, the flame retardancy deteriorates. On the other hand, if it exceeds 270 parts by mass, the content of the thermally conductive filler becomes relatively small, and the thermal conductivity deteriorates. When it is 175 to 270 parts by mass, excellent flame retardancy can be exhibited. Further, it does not harden after being subjected to a heat history that occurs when aluminum hydroxide or magnesium hydroxide is used as a flame retardant.
ベーマイトの平均粒径は、０．５〜５０μｍであることが好ましく、５μｍ以下がより好ましく、１μｍ以下が最も好ましい。０．５μｍ未満の場合には、比表面積が大きくなりすぎるため、難燃性を高めるための必要量を配合できなくなるおそれがある。一方、５０μｍを超える場合には、比表面積が小さくなりすぎるため、難燃性を向上させ難くなる。０．５〜５μｍの場合には、粒径が５μｍ以下の熱伝導性充填材とともに好適に分散し、柔軟性と難燃性が良好になる。 The average particle size of boehmite is preferably 0.5 to 50 μm, more preferably 5 μm or less, and most preferably 1 μm or less. If it is less than 0.5 μm, the specific surface area becomes too large, and it may not be possible to blend the necessary amount for increasing the flame retardancy. On the other hand, when it exceeds 50 μm, the specific surface area becomes too small and it becomes difficult to improve the flame retardancy. In the case of 0.5 to 5 μm, the particle size is suitably dispersed together with the thermally conductive filler having a particle size of 5 μm or less, and the flexibility and flame retardancy are improved.
添加剤： 熱伝導性シートとしての機能を損なわない範囲で種々の添加剤を含ませることができる。例えば、可塑剤、分散剤、カップリング剤、粘着剤などの有機成分を含んでも良い。またその他の成分として難燃剤、酸化防止剤、着色剤などを適宜添加してもよい。 Additives: Various additives can be included within the range of not impairing the function of the heat conductive sheet. For example, it may contain an organic component such as a plasticizer, a dispersant, a coupling agent, and an adhesive. In addition, flame retardants, antioxidants, colorants and the like may be added as appropriate as other components.
熱伝導性組成物の製造は、マトリクスとなる液状物（硬化前のマトリクス）に熱伝導性充填材とベーマイト、その他の必要な添加剤を加えて十分に攪拌、分散させる。液状物が主剤と硬化剤からなる場合は、それらの何れか一方に熱伝導性充填材等の固形分を混合させてから、熱伝導性充填材等の固形分を含まない主剤と硬化剤の何れか他方を混合しても良いし、主剤と硬化剤の両者に熱伝導性充填材等の固形分をそれぞれ混合してから、その主剤と硬化剤とを混合しても良い。 In the production of the heat conductive composition, a heat conductive filler, boehmite, and other necessary additives are added to a liquid material (matrix before curing) to be a matrix, and sufficiently stirred and dispersed. When the liquid material is composed of the main agent and the curing agent, after mixing the solid content of the thermally conductive filler or the like in any one of them, the main agent and the curing agent containing no solid content of the thermally conductive filler or the like Either one of them may be mixed, or both of the main agent and the curing agent may be mixed with solid components such as a thermally conductive filler, and then the main agent and the curing agent may be mixed.
こうした熱伝導性シートは、以下の性質を備える。
まず、熱伝導性シートの厚み方向の熱伝導率は、１．０〜１０Ｗ／ｍ・Ｋ程度であり、少なくとも１．０〜２．０Ｗ／ｍ・Ｋであることが好ましい。１．０Ｗ／ｍ・Ｋ以上あれば熱伝導性シートとして要求される最低限の熱伝導性を備えるからである。
Such a heat conductive sheet has the following properties.
First, the thermal conductivity in the thickness direction of the thermally conductive sheet is about 1.0 to 10 W / m · K, and preferably at least 1.0 to 2.0 W / m · K. This is because if it is 1.0 W / m · K or more, it has the minimum thermal conductivity required for the thermal conductive sheet.
熱伝導性シートの硬さ（柔らかさ）は、日本工業規格であるＪＩＳ Ｋ６２５３のタイプＥ硬度計によって測定されるＥ硬度で５〜９０とすることが好ましい。
Ｅ硬度がＥ５よりも低い場合は、柔軟過ぎることからハンドリングが難しくなり、取り扱い性が悪くなるおそれがある。そうした一方でＥ９０を超える場合は、熱伝導性シート全体が硬くなり、発熱体や放熱体の形状への追従性が悪化し、発熱体や放熱体と熱伝導性シートとの密着性が低下して熱伝導性が低下するおそれがある。
The hardness (softness) of the heat conductive sheet is preferably 5 to 90 in terms of E hardness measured by a type E hardness meter of JIS K6253 which is a Japanese industrial standard.
When the E hardness is lower than E5, it is too soft and therefore difficult to handle and the handleability may be deteriorated. On the other hand, when E90 is exceeded, the heat conductive sheet as a whole becomes hard, the conformability to the shape of the heat generating element or the heat radiating element deteriorates, and the adhesion between the heat generating element or the heat radiating element and the heat conductive sheet decreases. The thermal conductivity may decrease.
熱伝導性シートの難燃性は、米国アンダー・ライターズ・ラボラトリーズ・インク（Ｕｎｄｅｒ Ｗｒｉｔｅｒｓ Ｌａｂｏｒａｔｏｒｉｅｓ Ｉｎｃ）によって制定された燃焼試験（ＵＬ９４）による評価でＶ−０を備えるものである。この評価がＶ−１以下になると、要求される難燃性の基準を満たさないからである。 The flame-retardant property of the heat-conductive sheet is V-0 according to the evaluation by the combustion test (UL94) established by Under Writers Laboratories Inc. in the United States. This is because when the evaluation is V-1 or less, the required flame retardancy standard is not satisfied.
より具体的に実施例を示して本発明をさらに説明する。
＜熱伝導性シートの作製＞：
以下に示す方法で、試料１〜１８の熱伝導性シート１〜１８を作製した。
The present invention will be further described with reference to examples.
<Production of heat conductive sheet>:
The heat conductive sheets 1 to 18 of samples 1 to 18 were produced by the method described below.
試料１： マトリクスＡとして縮合反応型シリコーン（２６００ｍＰａ・ｓ、５％重量減少温度４４２℃）に、難燃剤としてベーマイト（不定形、平均粒径０．９μｍ）と、熱伝導性充填材として、酸化アルミニウムＡ（球状、平均粒径３．４μｍ、５μｍ以下の粒子の含有量６０質量％）と酸化アルミニウムＣ（球状、平均粒径７３μｍ、５μｍ以下の粒子の含有量０．１質量％）と、を表１で示す割合（それぞれ質量部で示す）で配合し、さらに酸化鉄５質量部およびシランカップリング剤５質量部（表には示さず）とを配合し、攪拌混合した後に脱泡して熱伝導性シート成形用の混合組成物１を調製した。そして、この混合組成物１を硬化成形して熱伝導性シート１を得た。 Sample 1 : Condensation reaction type silicone (2600 mPa · s, 5% weight loss temperature 442 ° C.) as matrix A, boehmite (amorphous, average particle size 0.9 μm) as flame retardant, and oxidation as heat conductive filler Aluminum A (spherical, content of particles having an average particle size of 3.4 μm, 5 μm or less 60% by mass) and aluminum oxide C (spherical, content of particles having an average particle size of 73 μm, 5 μm or less 0.1% by mass), At a ratio shown in Table 1 (each shown in parts by mass), further 5 parts by mass of iron oxide and 5 parts by mass of a silane coupling agent (not shown in the table) were mixed, stirred and mixed, and then defoamed. To prepare a mixed composition 1 for molding a thermally conductive sheet. Then, the mixed composition 1 was cured and molded to obtain a heat conductive sheet 1.
試料２〜試料１８： 試料２〜１８の熱伝導性シート１〜１８は、マトリクス、ベーマイト、熱伝導性充填材について、表１〜表４に示す材料および配合割合に変更した以外は、試料１の熱伝導性シート１と同様にして混合組成物２〜１８作製し、硬化成形して作製した。なお、表中の熱伝導性充填材としての水酸化アルミニウムは不定形で平均粒径８μｍであり、マトリクスＢは縮合反応型シリコーン（３７００ｍＰａ・ｓ、５％重量減少温度３５２℃）、酸化アルミニウムＢは、球状で平均粒径１０μｍ、５μｍ以下の粒子の含有量が２５質量％である。
＜各種特性の試験＞：
試料１〜試料１８の熱伝導性シート１〜１８について以下に示す種々の特性について試験を行った。
<Test of various characteristics>:
The heat conductive sheets 1 to 18 of Samples 1 to 18 were tested for various properties shown below.
難燃性試験： 熱伝導性シート１〜１８の難燃性について、米国アンダー・ライターズ・ラボラトリーズ・インク（Ｕｎｄｅｒ Ｗｒｉｔｅｒｓ Ｌａｂｏｒａｔｏｒｉｅｓ Ｉｎｃ）によって制定された燃焼試験（ＵＬ９４）を行い、難燃性について評価した。
具体的には、本試験用に混合組成物１〜１８の各々を硬化成形して、長さ：１２７ｍｍ、幅：１２．７ｍｍ、厚さ：１．０ｍｍの大きさの試験片を作製した。これらを固定用クランプに支持しバーナー（口径が１０ｍｍであり、長さが約１０ｃｍである）の炎に１０秒間接炎した後、炎から離して試験片の燃焼時間を記録した。試験片の消炎後、試験片を再度、炎に１０秒間接炎させ、その後、炎から離して試験片の燃焼時間を記録した。さらに２回目の接炎後、火種の保持時間（グローイング時間）と、試験片の下方に配置されている脱脂綿を発火させる滴下物の有無とを記録した。以上の操作を各試験片について５回１組として行った。得られた結果を表５に記した判定基準と照らし合せ、各試料の難燃性のグレードを判定した。この結果を表１〜表４に示す。
Flame Retardancy Test : The flame resistance of the heat conductive sheets 1 to 18 was evaluated by conducting a combustion test (UL94) established by Under Writers Laboratories Inc. of the United States. did.
Specifically, each of the mixed compositions 1 to 18 was cured and molded for this test to prepare a test piece having a size of 127 mm in length, 12.7 mm in width, and 1.0 mm in thickness. These were supported by a clamp for fixation and subjected to an indirect flame to a flame of a burner (having a diameter of 10 mm and a length of about 10 cm) for 10 seconds, and then separated from the flame to record the burning time of the test piece. After the test piece was extinguished, the test piece was again subjected to an indirect flame for 10 seconds and then removed from the flame and the burn time of the test piece was recorded. After the second flame contact, the holding time of the fire species (glowing time) and the presence / absence of drops that ignite the absorbent cotton disposed below the test piece were recorded. The above operation was performed 5 times for each test piece as one set. The obtained results were compared with the criteria shown in Table 5 to determine the flame retardancy grade of each sample. The results are shown in Tables 1 to 4.
耐熱性試験： 熱伝導性シート１〜１８の耐熱性について、２００℃の雰囲気中で１０００時間放置した後の屈曲強度の変化から評価した。
具体的には、本試験用に混合組成物１〜１８の各々を硬化成形して、３０ｍｍ×６０ｍｍ×１ｍｍの大きさの試験片を各々１０個作製した。次いで、１０個のうちの５個の試験片については２００℃の雰囲気中で１０００時間放置した。
Heat resistance test : The heat resistance of the heat conductive sheets 1 to 18 was evaluated from the change in flexural strength after being left for 1000 hours in an atmosphere of 200 ° C.
Specifically, each of the mixed compositions 1 to 18 was cured and molded for this test to prepare 10 test pieces each having a size of 30 mm × 60 mm × 1 mm. Then, 5 out of 10 test pieces were left to stand in an atmosphere of 200 ° C. for 1000 hours.
次に、１０個の試験片(1)のうち、２００℃の雰囲気においた５個は１０００時間放置の後、それ以外の５個は試験片(1)の作製後、図１に示すように、２０ｍｍの間隔で配置した台座(2)に、試験片(1)の長手方向が橋渡しする方向になるようにこれらの試験片(1)を乗せた。そして、試験片(1)の中央をプッシュルプゲージ(3)（押圧子は先端が直径５ｍｍの円柱形状）で押圧したときの応力を測定した。
Next, of the 10 test pieces (1), 5 pieces placed in an atmosphere of 200 ° C. were left for 1000 hours, and the other 5 pieces were made as shown in FIG. The test pieces (1) were placed on the pedestals (2) arranged at intervals of 20 mm so that the longitudinal direction of the test pieces (1) was the bridging direction. Then, push Le Pugeji (3) the center of the test piece (1) (presser tip is cylindrical with a diameter of 5mm) was measured stress when pressed with.
この応力について、耐熱試験を行った５個の試験片と、耐熱試験を行わなかった５個の試験片のそれぞれの平均をとり、耐熱性試験後の試験片の応力が試験前の応力に対して７５〜１２５％であったものを“◎”とし、１２５を超え、１５０％以下であったものを“〇”とし、１５０％を超えたものを“×”と評価した。また、この結果を表１〜表４に示す。 With respect to this stress, the average of each of the five test pieces that were subjected to the heat resistance test and the five test pieces that were not subjected to the heat resistance test was calculated, and the stress of the test piece after the heat resistance test was compared with the stress before the test. Those having 75 to 125% were evaluated as “⊚”, those exceeding 125 and not more than 150% were evaluated as “◯”, and those exceeding 150% were evaluated as “x”. The results are shown in Tables 1 to 4.
熱伝導率試験： 熱伝導性シート１〜１８の熱伝導性について、京都電子工業社製迅速熱伝導率計ＱＴＭ−５００を用いて非定常法細線加熱法にて熱伝導率を測定し評価した。具体的には、本試験用に混合組成物１〜１８の各々を硬化して、厚さ０．５ｍｍのシート状に成形した。そして上記熱伝導率計により熱伝導率を測定した。その結果を表１〜表４に示す。 Thermal conductivity test : The thermal conductivity of each of the thermal conductive sheets 1 to 18 was evaluated by measuring the thermal conductivity using a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Manufacturing Co., Ltd. by the unsteady method fine wire heating method. . Specifically, each of the mixed compositions 1 to 18 was cured for this test and molded into a sheet having a thickness of 0.5 mm. Then, the thermal conductivity was measured by the above thermal conductivity meter. The results are shown in Tables 1 to 4.
硬さの試験： 熱伝導性シート１〜１８について、タイプＥデュロメータを用いてＥ硬度を測定し評価した。具体的には、本試験用に混合組成物１〜１８の各々を硬化して、厚さ１０．０ｍｍのシート状に成形した試験片の硬さを測定した。そして、Ｅ硬度で５〜９０の範囲内にあるものを“〇”、その範囲から外れるものを“×”と評価した。その結果を表１〜表４に示す。 Hardness test : For the heat conductive sheets 1 to 18, E hardness was measured and evaluated using a type E durometer. Specifically, each of the mixed compositions 1 to 18 was cured for this test, and the hardness of a test piece molded into a sheet having a thickness of 10.0 mm was measured. Then, those having an E hardness within the range of 5 to 90 were evaluated as “◯”, and those outside the range were evaluated as “x”. The results are shown in Tables 1 to 4.
＜各種特性の評価＞：
試料１〜１８の熱伝導性シート１〜１８について、上記試験によって得られた評価から次のように分析した。
<Evaluation of various characteristics>:
The heat conductive sheets 1 to 18 of Samples 1 to 18 were analyzed as follows from the evaluation obtained by the above test.
難燃性について： ベーマイトの添加量を１７５質量部とした試料１に対して、ベーマイトを２００質量部に増やした試料２でも、試料１と同様に難燃性は最も良いＶ−０の評価となったが、１５０質量部に減らした試料７では難燃性が悪化してＶ−１の評価となった。
一方、酸化アルミニウムの粒径に着目すると、平均粒径３．４μｍの酸化アルミニウムの添加量を５０質量部とした試料１に対して、７５質量部に増やした試料３でも、試料１と同様に難燃性は最も良いＶ−０の評価となったが、２５質量部に減らした試料８では難燃性が悪化してＶ−１の評価となった。
Regarding Flame Retardancy : Even in
On the other hand, focusing on the particle size of aluminum oxide, sample 3 increased to 75 parts by mass with respect to sample 1 in which the addition amount of aluminum oxide having an average particle size of 3.4 μm was 50 parts by mass, similarly to sample 1. The flame retardancy was rated as V-0, which was the best, but Sample 8 reduced to 25 parts by mass deteriorated the flame retardancy and was rated as V-1.
平均粒径が７３μｍの酸化アルミニウムの添加量を１５０質量部とした試料１に対して、１７５質量部に増やした試料４でも、また１２５質量部に減らした試料９でも、試料１と同様に難燃性は最も良いＶ−０の評価となった。
これらの結果から、試料１の配合に対して、ベーマイトまたは平均粒径３．４μｍの酸化アルミニウムの添加量を減らすと難燃性が悪化するが、平均粒径７３μｍの酸化アルミニウムの添加量は減らしても増やしても難燃性にほとんど影響しないことがわかる。
Similar to sample 1, neither sample 4 whose amount of aluminum oxide having an average particle size of 73 μm was 150 parts by mass, nor sample 4 whose amount was increased to 175 parts by mass or sample 9 whose amount was reduced to 125 parts by mass was used. The flammability was evaluated as the best V-0.
From these results, when the addition amount of boehmite or aluminum oxide having an average particle size of 3.4 μm is reduced with respect to the formulation of Sample 1, the flame retardancy deteriorates, but the addition amount of aluminum oxide having an average particle size of 73 μm is reduced. It can be seen that even if the amount is increased, the flame retardancy is hardly affected.
また、試料１の配合に対して、ベーマイトの添加量を２５質量部減らし、平均粒径３．４μｍの酸化アルミニウムの添加量を２５質量部増やした試料１０では、難燃性が悪化してＶ−１の評価となった。一方、これとは逆に試料１に対して、ベーマイトの添加量を２５質量部増やし、平均粒径３．４μｍの酸化アルミニウムの添加量を２５質量部減らした試料１２でも、難燃性が悪化してＶ−１の評価となった。これらのことから、ベーマイトの添加量の下限が１５０質量部で、平均粒径３．４μｍの酸化アルミニウムの添加量の下限が５０質量部であり、このことから粒径５μｍ以下の酸化アルミニウムの添加量は少なくとも３０質量部以上が必要であることがわかる。 In addition, in the sample 10 in which the addition amount of boehmite was reduced by 25 parts by mass and the addition amount of aluminum oxide having an average particle diameter of 3.4 μm was increased by 25 parts by mass with respect to the composition of the sample 1, the flame retardancy deteriorated and V The evaluation was -1. On the other hand, conversely to sample 1, the addition amount of boehmite was increased by 25 parts by mass and the addition amount of aluminum oxide having an average particle diameter of 3.4 μm was decreased by 25 parts by mass, but the flame retardance was deteriorated. It became V-1 evaluation. From these facts, the lower limit of the addition amount of boehmite is 150 parts by mass, and the lower limit of the addition amount of aluminum oxide having an average particle diameter of 3.4 μm is 50 parts by mass. Therefore, the addition amount of aluminum oxide having a particle diameter of 5 μm or less is added. It can be seen that the amount should be at least 30 parts by mass or more.
さらに、試料１の配合に対して酸化アルミニウムの大きさを変え、平均粒径３．４μｍの酸化アルミニウムを平均粒径１０μｍの酸化アルミニウムに変更した試料１３では、難燃性が悪化してＶ−１の評価となった。一方で、試料１に対して、平均粒径３．４μｍの酸化アルミニウムの添加量を減らして平均粒径７３μｍの酸化アルミニウムの添加量を増やした試料１２でも難燃性は良くないＶ−１の評価であった。これらのことから、平均粒径が３．４μｍと小さい粒径の酸化アルミニウムに難燃性を向上させる効果があることがわかる。 Further, in the sample 13 in which the size of the aluminum oxide was changed with respect to the composition of the sample 1 to change the aluminum oxide having the average particle diameter of 3.4 μm to the aluminum oxide having the average particle diameter of 10 μm, the flame retardance was deteriorated and V- It was evaluated as 1. On the other hand, in comparison with Sample 1, Sample 12 in which the addition amount of aluminum oxide having an average particle diameter of 3.4 μm is reduced and the addition amount of aluminum oxide having an average particle diameter of 73 μm is increased is also inferior to V-1 of flame retardance. It was an evaluation. From these, it can be seen that aluminum oxide having a small average particle diameter of 3.4 μm has an effect of improving flame retardancy.
ベーマイトを含まない試料１７は、難燃性が良くないＶ−１の評価となり、平均粒径３．４μｍの酸化アルミニウムを多量に添加してもＶ−０を達成できなかった。また、熱伝導性充填材を含まずベーマイトのみを１７５質量部添加した試料６でも難燃性が良くないＶ−１の評価となった。
これらの結果から、ベーマイトの添加だけでは難燃性に対する優れた効果は得られず、
ベーマイトを１７５質量部以上添加することに加え、平均粒径３．４μｍの酸化アルミニウムを５０質量部以上、即ち、粒径５μｍ以下の酸化アルミニウムを３０質量部以上添加することが難燃性で最も良いＶ−０の評価を得る条件であることがわかる。
Sample 17 containing no boehmite was evaluated as V-1 having poor flame retardancy, and V-0 could not be achieved even if a large amount of aluminum oxide having an average particle diameter of 3.4 μm was added. Further, even in the sample 6 in which 175 parts by mass of boehmite alone was added without including the thermally conductive filler, the flame retardancy was evaluated as V-1.
From these results, the addition of boehmite alone does not provide an excellent effect on flame retardancy,
In addition to adding 175 parts by mass or more of boehmite, adding 50 parts by mass or more of aluminum oxide having an average particle size of 3.4 μm, that is, adding 30 parts by mass or more of aluminum oxide having a particle size of 5 μm or less is the most flame retardant. It can be seen that this is a condition for obtaining a good V-0 evaluation.
耐熱性について： 難燃剤にベーマイトを用いた試料１〜１３は、耐熱性の評価が「◎」となり良好であったが、ベーマイトに代えて水酸化アルミニウムを用いた試料１４では、耐熱性の評価が「×」となった。この結果から、難燃剤に水酸化アルミニウムを用いると耐熱性が低下することがわかる。 Regarding heat resistance : Samples 1 to 13 using boehmite as the flame retardant had a good heat resistance evaluation of "⊚", but sample 14 using aluminum hydroxide in place of boehmite evaluated heat resistance. Became "x". From this result, it is understood that the heat resistance is lowered when aluminum hydroxide is used as the flame retardant.
耐熱性の評価が「◎」である試料１の配合に対してマトリクスを変え、５％重量減少温度が４４２℃であるマトリクスＡから５％重量減少温度が３５２℃のマトリクスＢに変更した試料１５では、その評価が「〇」であった。この結果から、試料１５ではマトリクスがやや劣化したと考えられることから、耐熱性の観点からマトリクスの５％重量減少温度は４００℃以上が好ましいことがわかる。 Sample 15 in which the matrix was changed with respect to the formulation of Sample 1 having a heat resistance evaluation of “⊚” and the matrix A having a 5% weight loss temperature of 442 ° C. was changed to a matrix B having a 5% weight loss temperature of 352 ° C. Then, the evaluation was "○". From this result, it is considered that the matrix of Sample 15 is slightly deteriorated, and therefore the 5% weight loss temperature of the matrix is preferably 400 ° C. or higher from the viewpoint of heat resistance.
熱伝導率について： 平均粒径３．４μｍの酸化アルミニウムと、平均粒径７３μｍの酸化アルミニウムの添加量を固定して、ベーマイトの添加量を変えた試料１，２，７の熱伝導率は、１．５５〜１．６１Ｗ／ｍ・Ｋの範囲内にあった。また、平均粒径７０μｍの酸化アルミニウムとベーマイトの添加量を固定して、平均粒径３．４μｍの酸化アルミニウムの添加量を変えた試料１，３，８の熱伝導率は、１．５３〜１．６２Ｗ／ｍ・Ｋの範囲内にあった。さらに、平均粒径３．４μｍの酸化アルミニウムとベーマイトの添加量を固定して、平均粒径７３μｍの酸化アルミニウムの添加量を変えた試料１，４，９の熱伝導率は、１．３５〜１．７９Ｗ／ｍ・Ｋの範囲内にあった。
Regarding thermal conductivity : The thermal conductivity of
これらの結果より、熱伝導率の変化は、ベーマイトや、平均粒径３．４μｍの酸化アルミニウムの添加量を変化させたときは小さい。これに比べて、平均粒径７３μｍの酸化アルミニウムの添加量を変化させたときは大きいことがわかる。このことから、平均粒径３．４μｍの酸化アルミニウムの添加量を変化させるよりも、粒径の大きな平均粒径７３μｍの酸化アルミニウムの添加量を変化させた方が効果的に熱伝導率を高めることができることがわかる。 From these results, the change in thermal conductivity is small when the addition amount of boehmite or aluminum oxide having an average particle diameter of 3.4 μm is changed. Compared with this, it can be seen that it is large when the addition amount of aluminum oxide having an average particle diameter of 73 μm is changed. From this, the thermal conductivity is effectively increased by changing the addition amount of the aluminum oxide having an average particle diameter of 73 μm, which has a large particle diameter, rather than changing the addition amount of the aluminum oxide having an average particle diameter of 3.4 μm. You can see that you can.
また、試料１〜１８の全ての熱伝導性シート１〜１８で、シートの厚み方向の熱伝導率の値が１．０〜２．０Ｗ／ｍ・Ｋの範囲内にあり、何れも所望の熱伝導性を備えていることがわかる。 Further, in all of the heat conductive sheets 1 to 18 of Samples 1 to 18, the value of the heat conductivity in the thickness direction of the sheet is in the range of 1.0 to 2.0 W / mK, and any of them is desired. It can be seen that it has thermal conductivity.
硬さについて： 試料１〜１８の何れの熱伝導性シート１〜１８も、Ｅ硬度で７０〜９０となり、何れも評価は「〇」であって、その硬さは好適である。 Hardness : Any of the heat conductive sheets 1 to 18 of Samples 1 to 18 has an E hardness of 70 to 90, and the evaluation is “◯”, and the hardness is suitable.
総合評価： 以上の結果より、難燃材としてベーマイトを用いると耐熱性が良いことがわかる。また、ベーマイトを１７５質量部以上、平均粒径３．４μｍの酸化アルミニウムを５０質量部以上、即ち粒径３．４μｍ以下の酸化アルミニウムを５０質量部以上添加することが難燃性Ｖ−０の評価を得る条件であるが、一方で、大きい粒径の酸化アルミニウムの添加量を増やすことで熱伝導率を効果的に高めることができるため、ベーマイトと平均粒径３．４μｍ以下の酸化アルミニウムの添加量は、最低限として残部を大きい粒径の酸化アルミニウムを可能な範囲で添加することが好ましいことがわかる。 Comprehensive evaluation : From the above results, it can be seen that heat resistance is good when boehmite is used as the flame retardant material. Further, it is flame retardant V-0 to add 175 parts by mass or more of boehmite and 50 parts by mass or more of aluminum oxide having an average particle size of 3.4 μm, that is, 50 parts by mass or more of aluminum oxide having a particle size of 3.4 μm or less. Although it is a condition for obtaining evaluation, on the other hand, since the thermal conductivity can be effectively increased by increasing the addition amount of aluminum oxide having a large particle size, it is possible to improve the thermal conductivity of boehmite and aluminum oxide having an average particle size of 3.4 μm or less. It will be understood that it is preferable to add the aluminum oxide having a large particle diameter to the rest as a minimum amount as much as possible.
上記実施形態や実施例で示した例は本発明の例示であり、本発明の趣旨を逸脱しない範囲で、実施形態の変更や、公知技術の付加、組合せ等を行い得るものであり、それらの技術もまた本発明の範囲に含まれるものである。 The examples shown in the above embodiments and examples are exemplifications of the present invention, and modifications of the embodiments, addition of known techniques, combinations, and the like can be performed without departing from the spirit of the present invention. Techniques are also within the scope of the invention.
１ 試験片
２ 台座
３ プッシュプルゲージ
1
Claims (8)
前記ベーマイトは、平均粒径が０．５〜５μｍであり、
前記熱伝導性充填材は、粒径が５μｍ以下の熱伝導性充填材粒子を３０質量部以上含み、
前記熱伝導性シートは、日本工業規格であるＪＩＳ Ｋ６２５３のタイプＥの硬度計によって測定されるＥ硬度が５〜９０であり且つ発熱体又は放熱体の形状に追従する柔軟性を有するものである熱伝導性シート。 A thermally conductive sheet containing 175 to 270 parts by mass of boehmite and 50 to 300 parts by mass of a thermally conductive filler having a thermal conductivity of 20 W / m · K or more with respect to 100 parts by mass of a matrix made of silicone. Yes,
The boehmite has an average particle size of 0.5 to 5 μm,
The thermally conductive filler contains 30 parts by mass or more of thermally conductive filler particles having a particle size of 5 μm or less,
The heat conductive sheet has an E hardness of 5 to 90 as measured by a JIS K6253 type E hardness meter, which is a Japanese industrial standard, and has flexibility to follow the shape of a heating element or a radiator. Thermally conductive sheet.
請求項１記載の熱伝導性シート。 The heat conductive sheet according to claim 1, wherein the matrix is a polymer having a 5% weight loss temperature of 400 ° C or higher.
請求項１または請求項２記載の熱伝導性シート。 The heat conductive sheet according to claim 1, wherein the matrix is condensation reaction type silicone.
前記ベーマイトは、平均粒径が０．５〜５μｍであり、
前記熱伝導性充填材は、粒径が５μｍ以下の熱伝導性充填材粒子を３０質量部以上含み、
前記マトリクスは、５％重量減少温度が４００℃以上の高分子であり、
前記マトリクスは、縮合反応型シリコーンであり、
前記熱伝導性シートは、日本工業規格であるＪＩＳ Ｋ６２５３のタイプＥの硬度計によって測定されるＥ硬度が５〜９０であり且つ発熱体又は放熱体の形状に追従する柔軟性を有する熱伝導性シート。 A thermal conductive sheet containing boehmite 175 to 270 parts by mass and thermal conductive filler 50 to 300 parts by mass having a thermal conductivity of 20 W / m · K or more with respect to 100 parts by mass of a matrix,
The boehmite has an average particle size of 0.5 to 5 μm,
The thermally conductive filler contains 30 parts by mass or more of thermally conductive filler particles having a particle size of 5 μm or less,
The matrix is a polymer having a 5% weight loss temperature of 400 ° C. or higher,
The matrix is a condensation reaction type silicone,
The heat conductive sheet has an E hardness of 5 to 90 as measured by a JIS K6253 type E hardness meter, which is a Japanese industrial standard, and has flexibility to follow the shape of a heating element or a radiator. Sheet.
請求項１〜請求項４何れか１項記載の熱伝導性シート。 The heat conductive sheet according to claim 1, wherein the heat conductive filler is aluminum oxide.
請求項１〜請求項５何れか１項記載の熱伝導性シート。 6. The flame retardancy evaluation according to a combustion test (UL94) established by Under Writers Laboratories Inc. in the United States provides V-0 according to any one of claims 1 to 5. The heat conductive sheet described.
請求項１〜請求項６何れか１項記載の熱伝導性シート。 The heat conductive sheet according to any one of claims 1 to 6, wherein a change in flexural strength after leaving for 1000 hours in an atmosphere of 200 ° C is within 75 to 150%.
請求項１〜請求項７何れか１項記載の熱伝導性シート。 The said heat conductive filler consists of 30 mass parts or more of heat conductive filler particles with a particle size of 5 micrometers or less, and the remainder which consists of heat conductive filler particles with a particle diameter of more than 5 micrometers. Item 7. The heat conductive sheet according to any one of items 7.
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