JP2021048280A - Graphite integrated film, manufacturing method of graphite integrated film, thermoelectric conversion layer using graphite integrated film, and heat dissipation material with thermocouple function or thermoelectric power generation function - Google Patents
Graphite integrated film, manufacturing method of graphite integrated film, thermoelectric conversion layer using graphite integrated film, and heat dissipation material with thermocouple function or thermoelectric power generation function Download PDFInfo
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Abstract
Description
本発明は、グラファイト集積膜、グラファイト集積膜の製造方法、並びに該グラファイト集積膜を用いた熱電変換層及び熱電対機能ないし熱発電機能つき放熱材に関する。 The present invention relates to a graphite integrated film, a method for producing a graphite integrated film, a thermoelectric conversion layer using the graphite integrated film, and a heat radiating material having a thermocouple function or a thermoelectric power generation function.
グラファイト、およびそれを薄片化したグラフェンは、面内方向において非常に高い熱伝導率を持つ（非特許文献１）。この特長を活かし、自動車の制御用電子部品や一般用電子機器の発熱部品からの放熱を行う部材として、グラファイト放熱基板が開発されている（特許文献１）。 Graphite and graphene, which is a slice of graphite, have extremely high thermal conductivity in the in-plane direction (Non-Patent Document 1). Taking advantage of this feature, a graphite heat-dissipating substrate has been developed as a member that dissipates heat from electronic parts for controlling automobiles and heat-generating parts of general-purpose electronic devices (Patent Document 1).
また、放熱時の発熱部品の温度計測を行うため、放熱用のヒートシンク内に熱電対を埋め込む技術がある（特許文献２）。 Further, there is a technique of embedding a thermocouple in a heat sink for heat dissipation in order to measure the temperature of heat-generating parts at the time of heat dissipation (Patent Document 2).
一方、排熱をエネルギーとして有効利用するために、複数の熱電変換素子を接続してなる熱電変換モジュール（発電装置）が用いられており、熱電変換層に、グラフェン又はその炭素原子の一部がヘテロ原子で置換されたグラフェン、或いは、グラフェン積層体（グラファイト）又はグラファイトの層間にゲスト剤（挿入化合物）が挿入されたグラファイト層間化合物を用いて、熱電変換素子を形成する技術がある（特許文献３）。 On the other hand, in order to effectively utilize the exhaust heat as energy, a thermoelectric conversion module (power generation device) formed by connecting a plurality of thermoelectric conversion elements is used, and graphene or a part of its carbon atom is contained in the thermoelectric conversion layer. There is a technique for forming a thermoelectric conversion element using graphene substituted with a hetero atom, graphene laminate (graphite), or a graphite interlayer compound in which a guest agent (insertion compound) is inserted between graphite layers (Patent Documents). 3).
特許文献１を例とした従来のグラファイト放熱基板は、発熱部品からの放熱を行うことのみを目的としており、それ自体で温度計測を行う機能や熱発電の機能は有していない。
The conventional graphite heat radiating substrate of
また、特許文献２のように放熱時の発熱部品の温度計測を目的として放熱用のヒートシンク内に熱電対を埋め込む技術の場合、ヒートシンクへの加工や熱電対の接合を要するだけでなく、接合した熱電対が熱伝導を妨げて本来の放熱性能を低下させる他、発熱部品と熱電対との間の熱抵抗を下げることが困難であり、発熱部品の正確な温度計測を行うことを困難とする。
Further, in the case of a technique of embedding a thermocouple in a heat sink for heat dissipation for the purpose of measuring the temperature of heat-generating parts at the time of heat dissipation as in
さらに、特許文献３のようにグラファイトやグラフェンを用いた熱電変換素子では、Ｐ型及びＮ型のキャリアドーピングを可能にし、熱電発電や熱電対としての機能を持たせることは可能であるが、ドーピングのために炭素原子の一部を他の原子に置換したり、グラファイト原子層間に化合物を挿入したりすると、それらがフォノン散乱を起こして熱伝導を妨げるため、従来の放熱用に用いられるグラファイト基板に比べて熱伝導率及び熱拡散率が数〜数十分の一に低下し、放熱材としての利用は困難である。
さらに、これらの化合物は真空や高温での化学反応を要するため製造時の投入エネルギーが大きい他、グラファイト層間化合物は不安定で脱離しやすいため封止剤が必要であり、これがさらに熱抵抗を生じて放熱性を低下させる。加えて、グラファイト層間化合物においてグラファイト層間に挿入される物質は、塩化銅や塩化鉄等の腐食性の高い物質であり、周囲の金属部品や電子部品を腐食し損傷するおそれがある。
Further, in a thermoelectric conversion element using graphite or graphene as in
Furthermore, since these compounds require a chemical reaction at vacuum or high temperature, the input energy during production is large, and since the graphite interlayer compounds are unstable and easily desorbed, a sealant is required, which further causes thermal resistance. To reduce heat dissipation. In addition, in the graphite interlayer compound, the substance inserted between the graphite layers is a highly corrosive substance such as copper chloride and iron chloride, which may corrode and damage surrounding metal parts and electronic parts.
以上のとおり、グラファイトやグラフェンを用いた熱電変換素子においては、放熱用に充分な熱伝導率及び熱拡散率を有するものはなかったため、放熱材として使用するとともにその放熱機能を利用したまま温度計測や熱発電に用いるという試みはこれまでなかった。
本発明は、このような事情を鑑みてなされたものであり、グラファイトやグラフェンを用いて、簡便な方法で、放熱用に充分な熱伝導率及び熱拡散率を有するとともに、熱電変換機能を有する集積膜を得ることを目的とするものである。また、本発明は、得られた集積膜を用いて、熱電変換素子、或いは熱電対機能ないし発電機能付き放熱材を提供することをもう１つの目的とするものである。
As described above, none of the thermoelectric conversion elements using graphite or graphene have sufficient thermal conductivity and thermal diffusivity for heat dissipation, so they are used as heat dissipation materials and the temperature is measured while using the heat dissipation function. There has been no attempt to use it for thermal power generation.
The present invention has been made in view of such circumstances, and has a thermal conductivity and a thermal diffusivity sufficient for heat dissipation and a thermoelectric conversion function by a simple method using graphite or graphene. The purpose is to obtain an integrated membrane. Another object of the present invention is to provide a thermoelectric conversion element or a heat radiating material having a thermocouple function or a power generation function by using the obtained integrated film.
本発明者は、前記目的を達成するために種々の検討を行った結果、従来の、グラファイトまたはグラフェンの中の炭素原子の一部を他の原子に置換したり、グラファイト原子層間に化合物を挿入したりする等の方法に代えて、入手が容易な薄片化グラファイト粉末を用い、これを、界面活性剤等の荷電特性を制御可能な化合物の水溶液中に分散してその表面を該水溶液で被覆した後、得られた薄片化グラファイト粉末の分散液を濾過・成膜する、という簡便な方法を用いることにより、上記目的を達成しうることを見いだした。 As a result of various studies to achieve the above object, the present inventor replaces a part of carbon atoms in conventional graphite or graphene with other atoms, or inserts a compound between graphite atom layers. Instead of a method such as squeezing, flaky graphite powder, which is easily available, is used, and this is dispersed in an aqueous solution of a compound whose charging characteristics can be controlled such as a surfactant, and the surface thereof is coated with the aqueous solution. After that, it was found that the above object can be achieved by using a simple method of filtering and forming a film of the obtained dispersion of the flaky graphite powder.
すなわち、上記方法によれば、薄片化グラファイト粉末の表面に、界面活性剤等の荷電特性を制御可能な化合物が吸着され、得られたグラファイト集積膜は、荷電特性を制御可能な化合物とグラファイトの間の電荷移動により、所望する適切なキャリア濃度を持たせることが可能となり、熱電変換機能を有するグラファイト集積膜を形成しうること、及びこうして得られたグラファイト集積膜では、グラファイト薄片表面に極微量存在する界面活性剤等の荷電特性制御化合物によるフォノン散乱は小さいため、熱伝導率の低下は小さく、市販のヒートシンクに利用されるアルミニウムの熱伝導率（室温で２３６Ｗ／ｍＫ）以上の高い熱伝導率を有し、当該グラファイト集積膜を市販のグラファイトシートと接合した場合においても、グラファイトシートの８０％以上の熱伝導率を有することが判明した。
また、界面活性剤等の荷電特性制御化合物の種類や濃度を変えることにより、Ｐ型Ｎ型のキャリアタイプやキャリア濃度を制御した２種類のグラファイト集積膜を得ることができ、これらの一端を接合し、その接合部分ともう片方の端との温度差をゼーベック（Seebeck）効果によって熱起電力に変換することにより、接合部分の温度を計測することができることも判明した。
この放熱と温度計測の機能はＰＮ接合された１枚の膜で実現でき、接合部に発熱部品を設置するだけで発熱部品の温度計測と放熱を同時に行うことができ、さらに、放熱を行いながら、熱電変換により発電を行うことも可能であり、１つの部材で発熱部を冷却しながら微小電源としても機能する。
That is, according to the above method, a compound having controllable charge characteristics such as a surfactant is adsorbed on the surface of the flaky graphite powder, and the obtained graphite integrated film is obtained from a compound having controllable charge characteristics and graphite. The transfer of charge between them makes it possible to have a desired appropriate carrier concentration, and it is possible to form a graphite integrated film having a thermoelectric conversion function, and in the graphite integrated film thus obtained, a very small amount is applied to the surface of the graphite flakes. Since phonon scattering by existing charge property control compounds such as surfactants is small, the decrease in thermal conductivity is small, and the thermal conductivity is higher than that of graphite used for commercially available heat sinks (236 W / mK at room temperature). It was found that it has a thermal conductivity of 80% or more of that of the graphite sheet even when the graphite integrated film is bonded to a commercially available graphite sheet.
Further, by changing the type and concentration of the charge characteristic control compound such as a surfactant, it is possible to obtain a P-type N-type carrier type and two types of graphite integrated films in which the carrier concentration is controlled, and one end of these is bonded. However, it was also found that the temperature of the joint can be measured by converting the temperature difference between the joint and the other end into thermoelectromotive force by the Seebeck effect.
This heat dissipation and temperature measurement function can be realized with a single PN-junctioned membrane, and the temperature and heat dissipation of the heat-generating parts can be performed at the same time simply by installing the heat-generating parts at the joint, and while radiating heat, It is also possible to generate electricity by thermoelectric conversion, and it also functions as a minute power source while cooling the heat generating part with one member.
本発明は、これらの知見に基づいて完成に至ったものであり、以下のとおりである。
［１］薄片化グラファイト粉末が堆積されてなる膜であって、前記薄片化グラファイト粉末の表面に、荷電特性を制御可能な化合物が吸着されていることを特徴とするグラファイト集積膜。
［２］前記荷電特性を制御可能な化合物が、陽イオン系界面活性剤又は陰イオン系界面活性剤であることを特徴とする［１］に記載のグラファイト集積膜。
［３］薄片化したグラファイト粉末を、荷電特性を制御可能な化合物の水溶液中に分散すること、及び
得られた薄片化グラファイト粉末の分散液を濾過後、成膜すること
を含むグラファイト集積膜の製造方法。
［４］前記荷電特性を制御可能な化合物が、陽イオン系界面活性剤又は陰イオン系界面活性剤であることを特徴とする［３］に記載のグラファイト集積膜の製造方法。
［５］Seebeck係数及び導電率が調整された［１］又は［２］に記載のグラファイト集積膜を用いたことを特徴とする熱電変換層。
［６］前記グラファイト集積膜の少なくとも一面に、酸化グラフェン集積膜からなる絶縁層を有する［５］に記載の熱電変換層。
［７］グラファイトないしグラファイト集積膜から構成された導電体と、その導電体のSeebeck係数と異なるSeebeck係数を持つグラファイトないしグラファイト集積膜から構成された導電体の２種類の導電体を接合させるとともに、両導電体の間に絶縁体を介在させてなる熱電対であって、
これら２つの導電体の少なくとも一方が［５］に記載の熱電変換層で構成され、
前記絶縁体が酸化グラフェン集積膜で構成されていることを特徴とする熱電対。
［８］構成要素の少なくとも一部に、［７］に記載の熱電対を用いた熱電対機能付き放熱材。
［９］グラファイトないしグラファイト集積膜から構成された導電体と、その導電体のSeebeck係数と異なるSeebeck係数を持つグラファイトないしグラファイト集積膜から構成された導電体の２種類の導電体を接合させるとともに、両導電体の間に絶縁体を介在させてなる熱発電素子であって、
これら２つの導電体の少なくとも一方が［５］に記載の熱電変換層で構成され、
前記絶縁体が酸化グラフェン集積膜で構成されていることを特徴とする熱発電素子。
［１０］構成要素の少なくとも一部に、［９］に記載の熱発電素子を用いた熱発電機能付き放熱材。
The present invention has been completed based on these findings, and is as follows.
[1] A film formed by depositing flaky graphite powder, wherein a compound whose charging characteristics can be controlled is adsorbed on the surface of the flaky graphite powder.
[2] The graphite integrated film according to [1], wherein the compound whose charge characteristics can be controlled is a cationic surfactant or an anionic surfactant.
[3] A graphite integrated film comprising dispersing the fragmented graphite powder in an aqueous solution of a compound whose charge characteristics can be controlled, and filtering the obtained dispersion of the fragmented graphite powder to form a film. Production method.
[4] The method for producing a graphite integrated film according to [3], wherein the compound whose charge characteristics can be controlled is a cationic surfactant or an anionic surfactant.
[5] A thermoelectric conversion layer using the graphite integrated film according to [1] or [2], wherein the Seebeck coefficient and conductivity have been adjusted.
[6] The thermoelectric conversion layer according to [5], which has an insulating layer made of a graphene oxide integrated film on at least one surface of the graphite integrated film.
[7] Two types of conductors, a conductor composed of graphite or graphite integrated film and a conductor composed of graphite or graphite integrated film having a Seebeck coefficient different from the Seebeck coefficient of the conductor, are bonded together. A thermocouple with an insulator interposed between both conductors.
At least one of these two conductors is composed of the thermoelectric conversion layer according to [5].
A thermocouple characterized in that the insulator is composed of a graphene oxide integrated film.
[8] A heat radiating material with a thermocouple function using the thermocouple according to [7] for at least a part of the components.
[9] Two types of conductors, a conductor composed of graphite or graphite integrated film and a conductor composed of graphite or graphite integrated film having a Seebeck coefficient different from the Seebeck coefficient of the conductor, are bonded together. It is a thermal power generation element in which an insulator is interposed between both conductors.
At least one of these two conductors is composed of the thermoelectric conversion layer according to [5].
A thermoelectric power generation element characterized in that the insulator is composed of a graphene oxide integrated film.
[10] A heat radiating material with a thermoelectric power generation function using the thermoelectric power generation element according to [9] as at least a part of the constituent elements.
本発明によれば、簡便で、しかも周囲の金属部品や電子部品を損傷するおそれのない方法で、所望のキャリア濃度を持たせることが可能となり、熱電変換機能を有するグラファイト集積膜を形成することができる。また、本発明によれば、グラファイト薄片表面に微量存在する界面活性剤等の荷電特性制御化合物によるフォノン散乱は小さいため、熱伝導率の低下が少ないグラファイト集積膜が得られ、さらに、界面活性剤等の荷電特性制御化合物の種類や濃度を変えてＰ型Ｎ型のキャリアタイプやキャリア濃度を制御した２種類のグラファイト集積膜の一端を接合し、その接合部分ともう片方の端との温度差をゼーベック（Seebeck）効果によって熱起電力に変換することにより、接合部分の温度を計測することができる。
したがって、本発明のグラファイト集積膜を用いれば、電気自動車や電子機器等に用いられるパワー半導体や、電池等の種々の発熱部品の温度計測と放熱の２つの機能を１つの部材で兼ね備えることができるため、温度測定部位に別途、熱電対を設置する必要がない。
また、本発明のグラファイト集積膜を用いれば、発熱試験時だけでなく、実際の使用時における電気自動車や電子機器等のパワー半導体等の発熱状態を監視できるという、これまでにない機能が実現でき、これにより、これらの機器の熱診断や熱マネージメントを可能にし、その長寿命化に貢献する。
さらに、本発明のグラファイト集積膜を熱電変換層として利用する場合も、従来よりも簡便な製造方法で発電性能の高い部材を作ることができ、部材の温度差を適切に与えれば熱発電も可能であり、放熱フィンやヒートシンクとして利用しながらそれ自体が発電するなど、種々の熱源から電力を得てセンサーや通信を自立駆動できる孤立微小電源にも応用できる。
According to the present invention, it is possible to give a desired carrier concentration by a simple method that does not damage surrounding metal parts and electronic parts, and to form a graphite integrated film having a thermoelectric conversion function. Can be done. Further, according to the present invention, since phonon scattering by a charge characteristic control compound such as a surfactant present in a trace amount on the surface of the graphite flakes is small, a graphite integrated film having a small decrease in thermal conductivity can be obtained, and further, a surfactant. One end of two types of graphite integrated membranes whose P-type N-type carrier type and carrier concentration are controlled by changing the type and concentration of the charge characteristic control compound such as, etc. is bonded, and the temperature difference between the bonded portion and the other end. Can be converted into thermoelectromotive charge by the Seebeck effect, so that the temperature of the interface can be measured.
Therefore, by using the graphite integrated film of the present invention, one member can have two functions of temperature measurement and heat dissipation of various heat generating parts such as power semiconductors used in electric vehicles and electronic devices and batteries. Therefore, it is not necessary to separately install a thermocouple at the temperature measurement site.
Further, by using the graphite integrated film of the present invention, it is possible to realize an unprecedented function of monitoring the heat generation state of power semiconductors of electric vehicles and electronic devices not only during the heat generation test but also during actual use. This enables thermal diagnosis and thermal management of these devices and contributes to their long life.
Further, even when the graphite integrated film of the present invention is used as a thermoelectric conversion layer, a member having high power generation performance can be produced by a simpler manufacturing method than before, and thermal power generation is also possible if the temperature difference of the member is appropriately given. It can also be applied to an isolated micro power source that can independently drive sensors and communications by obtaining power from various heat sources, such as generating electricity by itself while using it as a heat dissipation fin or heat sink.
本発明のグラファイト集積膜は、薄片化グラファイトの粉末が堆積されてなる膜であって、該薄片化グラファイトの粉末の表面に、荷電特性を制御可能な化合物が吸着していることを特徴とする。 The graphite integrated film of the present invention is a film formed by depositing flaky graphite powder, and is characterized in that a compound whose charging characteristics can be controlled is adsorbed on the surface of the flaky graphite powder. ..
本発明のグラファイト集積膜は、薄片化したグラファイト粉末を、荷電特性を制御可能な化合物の水溶液中に分散してその表面を該水溶液で被覆し、得られた薄片化グラファイト粉末の分散液を濾過後、成膜することにより製造することができる。 In the graphite integrated film of the present invention, the thinned graphite powder is dispersed in an aqueous solution of a compound whose charge characteristics can be controlled, the surface thereof is coated with the aqueous solution, and the obtained dispersion of the thinned graphite powder is filtered. After that, it can be produced by forming a film.
以下、本発明の実施形態について詳しく説明するが、本発明はこれらの実施形態に限定されるものではない。なお、数値範囲の記載（２つの数値を「〜」でつないだ記載）については、下限及び上限として記載された数値をも含む意味である。 Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. The description of the numerical range (the description in which two numerical values are connected by "~") means that the numerical values described as the lower limit and the upper limit are also included.
（薄片化グラファイト粉末）
本発明における薄片化グラファイト粉末は、後述する方法でも製造できるが、入手が容易である市販のものを用いることが好ましく、例えば、市販品として利用できる薄片化グラファイト粉末としては、アイテック社のiGrafen-aがある。
(Sliced graphite powder)
The flaky graphite powder in the present invention can be produced by the method described later, but it is preferable to use a commercially available flaky graphite powder that is easily available. For example, as the flaky graphite powder that can be used as a commercial product, iGrafen- of Aitec Co., Ltd. There is a.
薄片化グラファイト粉末の製造方法としては大きく分けて２種類の方法を選択することができる。
１つ目の製造方法は、原料となる黒鉛（グラファイト）の層間に化合物を侵入又は挿入させた後、これを加熱することによって当該化合物の気化又は膨張を生じさせ、グラファイト層間を剥離させる工程を経て製造されるものである。グラファイト層間に侵入又は挿入させる化合物としては、加熱処理によって気化又は膨張可能なものであれば、酸、ハロゲン化合物、あるいは気体分子のいずれを用いてもよい。酸としては、硝酸、塩酸、硫酸、等が挙げられる。ハロゲン化合物としては、塩化鉄、塩化銅等が挙げられる。気体分子としては、二酸化炭素が挙げられる。化合物の気化又は膨張を生じさせる手法としては、直接加熱又はマイクロ波照射等を用いることができる。
本発明においては、得られた薄片化グラファイトを、必要に応じて、所望の大きさの粉末にして用いる。
As a method for producing flaky graphite powder, two types of methods can be roughly selected.
The first production method is a step of invading or inserting a compound between layers of graphite (graphite) as a raw material and then heating the compound to cause vaporization or expansion of the compound and peeling off the graphite layers. It is manufactured after that. As the compound to be inserted or inserted between the graphite layers, any of an acid, a halogen compound, and a gas molecule may be used as long as it can be vaporized or expanded by heat treatment. Examples of the acid include nitric acid, hydrochloric acid, sulfuric acid, and the like. Examples of the halogen compound include iron chloride and copper chloride. Examples of gas molecules include carbon dioxide. Direct heating, microwave irradiation, or the like can be used as a method for causing vaporization or expansion of the compound.
In the present invention, the obtained flaky graphite is used as a powder of a desired size, if necessary.
２つ目の製造方法は、溶媒に分散したグラファイト粉末に高い応力、特に高いせん断力を付加してグラファイト層間の剥離を生じさせる工程を経て製造されるものであり、応力、特に高いせん断力を付加する方法としては、グラファイト層間を剥離させるのに十分なせん断力を持つ方法であれば、ミキサーを用いる方法、超音波を照射する方法、速度の異なる２本のロールでグラファイト分散液を挟み込む方法、等を用いることができる。
なお、この場合の溶媒としては、グラファイト粉末の分散性を高めるためにＮ-メチル−２−ピロリドン等の有機溶媒や硫酸アンモニウム等の水溶液を用いてもよいし、分散性と荷電特性の制御を兼ねて後述の各種界面活性剤を所定量混合した水溶液を用いてもよい。
後者の場合には、該水溶液中にせん断力が付与されて薄片化したグラファイト粉末が分散した分散液が得られるため、得られた分散液をそのまま用いて、濾過、成膜することにより、本発明のグラファイト集積膜が得られる。
The second production method is produced through a step of applying a high stress, particularly a high shear force, to the graphite powder dispersed in the solvent to cause separation between the graphite layers, and the stress, particularly a high shear force, is applied. As a method of addition, if the method has sufficient shearing force to separate the graphite layers, a method using a mixer, a method of irradiating ultrasonic waves, and a method of sandwiching the graphite dispersion liquid between two rolls having different velocities. , Etc. can be used.
As the solvent in this case, an organic solvent such as N-methyl-2-pyrrolidone or an aqueous solution such as ammonium sulfate may be used in order to enhance the dispersibility of the graphite powder, and the dispersibility and charge characteristics can be controlled. An aqueous solution obtained by mixing a predetermined amount of various surfactants described below may be used.
In the latter case, a dispersion liquid in which shearing force is applied to the aqueous solution and the thinned graphite powder is dispersed can be obtained. Therefore, the obtained dispersion liquid is used as it is, and filtered and formed into a film. The graphite integrated film of the present invention is obtained.
薄片化したグラファイトの単片の大きさは、面内方向の大きさ（粒径）と厚さの２つの数値で規定できる。放熱材及び熱電対又は熱電素子として適度な導電率と熱伝導率を備えるために、粒径としては、１μｍ以上であることが望ましく、２μｍ以上であることがより望ましい。加えて、グラファイトの荷電特性を適度に制御することが可能な厚さとしては、５０ｎｍ以下であることが望ましく、２０ｎｍ以下であることがより望ましい。さらには、粒径が前記のとおり１μｍ以上であって、集積膜の放熱性及び導電性を、薄片化したグラファイトの集積膜と同程度又はそれ以上にした場合において、厚さが約３ｎｍ以下の範囲のグラフェン（単層グラフェン、２層グラフェン、及び複数層グラフェン又は多層グラフェン）の集積膜を用いることもできる。 The size of the sliced graphite single piece can be defined by two numerical values, the size (particle size) in the in-plane direction and the thickness. The particle size is preferably 1 μm or more, and more preferably 2 μm or more, in order to have appropriate conductivity and thermal conductivity as a heat radiating material and a thermocouple or a thermoelectric element. In addition, the thickness at which the charge characteristics of graphite can be appropriately controlled is preferably 50 nm or less, and more preferably 20 nm or less. Furthermore, when the particle size is 1 μm or more as described above and the heat dissipation and conductivity of the integrated film are equal to or larger than that of the thinned graphite integrated film, the thickness is about 3 nm or less. An integrated film of a range of graphene (single-layer graphene, double-layer graphene, and multi-layer graphene or multi-layer graphene) can also be used.
（薄片化グラファイト粉末の分散）
本発明においては、前記の薄片化したグラファイト粉末を、荷電特性を制御可能な化合物の水溶液中に投入して分散処理を行うことにより、薄片化グラファイト粉末の表面が、界面活性剤等の荷電特性制御化合物の水溶液で均一に被覆されるようにするものであり、方法は特に限定されないが、超音波を印加して分散処理を行うことや、スターラーで撹拌することが好ましい。
(Dispersion of flaky graphite powder)
In the present invention, the flaky graphite powder is put into an aqueous solution of a compound whose charge characteristics can be controlled to carry out a dispersion treatment, so that the surface of the flaky graphite powder has charge characteristics such as a surfactant. It is intended to be uniformly coated with an aqueous solution of the control compound, and the method is not particularly limited, but it is preferable to apply ultrasonic waves to perform dispersion treatment or to stir with a stirrer.
（分散液の濾過・成膜）
次いで、得られた薄片化グラファイト粉末の分散液を濾過し、乾燥して水分を除去することで、表面に界面活性剤等の荷電特性制御化合物が吸着した薄片化グラファイト粉末の堆積物が得られる。その後、この堆積物にプレス処理を施すことにより、本発明のグラファイト集積膜が得られる。
プレス処理は、グラファイト堆積物を２枚の平面板で挟み、その上下面からの圧力でプレスするプレス機を用いてもよいし、グラファイト堆積物を２本のロールで挟み、ロール間の線圧でプレスするプレス機を用いてもよい。いずれのプレス機を用いた場合でも、得られる集積膜において、熱電対機能や熱発電機能に必要な導電率を持たせるため、プレスによる厚みの減少率、すなわち厚みの減少分をプレス前の元の厚みで割った値が、０．９以上に高いことが好ましい。集積膜の厚み自体は、放熱対象物の形状や放熱量に応じて適切な熱抵抗となるように、プレス前の堆積物の量を調整すればよい。
(Filtration / deposition of dispersion)
Next, the obtained dispersion of the flaky graphite powder is filtered and dried to remove water, whereby a deposit of the flaky graphite powder on which a charge characteristic control compound such as a surfactant is adsorbed can be obtained. .. Then, the deposit is pressed to obtain the graphite integrated film of the present invention.
For the pressing process, a press machine may be used in which the graphite deposit is sandwiched between two flat plates and pressed by the pressure from the upper and lower surfaces thereof, or the graphite deposit is sandwiched between two rolls and the linear pressure between the rolls is used. You may use a press machine that presses with. Regardless of which press machine is used, in order to give the obtained integrated film the conductivity required for the thermocouple function and the thermoelectric power generation function, the rate of decrease in thickness due to pressing, that is, the amount of decrease in thickness is the source before pressing. It is preferable that the value divided by the thickness of is as high as 0.9 or more. The thickness of the integrated film itself may be adjusted by adjusting the amount of deposits before pressing so that the heat resistance becomes appropriate according to the shape of the heat radiation object and the heat radiation amount.
（荷電特性を制御可能な化合物）
荷電特性を制御可能な化合物として、好ましくは、界面活性剤が用いられる。
用いられる界面活性剤はイオン系のものであれば特に限定されないが、例えば、陰イオン系界面活性剤としては、ドデシルベンゼンスルホン酸（ＤＢＳ）等の直鎖アルキルベンゼンスルホン酸及びその塩、ラウリル硫酸ナトリウム、コール酸ナトリウム等が挙げられ、また、陽イオン系界面活性剤としては、臭化ヘキサデシルトリメチルアンモニウム（ＣＴＡＢ）等のアルキルトリメチルアンモニウム塩、ジアルキルジメチルアンモニウム塩等が挙げられる。
また、界面活性剤以外では、ポリスチレンスルホン酸などのアニオン性高分子を利用することも可能である。
(Compounds whose charge characteristics can be controlled)
As a compound whose charge characteristics can be controlled, a surfactant is preferably used.
The surfactant used is not particularly limited as long as it is ionic, and examples of the anionic surfactant include linear alkylbenzene sulfonic acid such as dodecylbenzene sulfonic acid (DBS) and a salt thereof, and sodium lauryl sulfate. , Sodium oxalate and the like, and examples of the cationic surfactant include alkyltrimethylammonium salts such as hexadecyltrimethylammonium bromide (CTAB) and dialkyldimethylammonium salts.
In addition to the surfactant, it is also possible to use an anionic polymer such as polystyrene sulfonic acid.
本発明では、界面活性剤などの荷電特性を制御可能な化合物の種類を変えることにより、キャリアタイプがＰ型又はＮ型のグラファイト集積膜を得ることができ、陰イオン系界面活性剤又はポリスチレンスルホン酸などのアニオン性高分子を用いた場合には、Ｐ型のグラファイト集積膜が得られ、陽イオン系界面活性剤を用いた場合には、Ｎ型のグラファイト集積膜が得られる。 In the present invention, a graphite integrated film having a carrier type of P-type or N-type can be obtained by changing the type of a compound whose charge characteristics can be controlled, such as a surfactant, and an anionic surfactant or polystyrene sulfone can be obtained. When an anionic polymer such as an acid is used, a P-type graphite integrated film is obtained, and when a cationic surfactant is used, an N-type graphite integrated film is obtained.
また、界面活性剤などの荷電特性を制御可能な化合物の、水溶液中のモル濃度と、グラファイト集積膜に含まれる化合物の量とは相関しており、その結果、用いる界面活性剤等の荷電特性を制御可能な化合物の、水溶液中のモル濃度を変更することで、得られる集積膜のキャリア極性や熱電特性を変更することができる。（後述する図１３、１４参照） In addition, the molar concentration of a compound whose charging characteristics such as a surfactant can be controlled in an aqueous solution correlates with the amount of the compound contained in the graphite integrated membrane, and as a result, the charging characteristics of the surfactant or the like used are correlated. By changing the molar concentration of the compound that can control the above, the carrier polarity and thermoelectric properties of the obtained integrated membrane can be changed. (See FIGS. 13 and 14 described later)
後述する実施例では、用いる界面活性剤の水溶液のモル濃度は、ＤＢＳで１×１０−３〜５００×１０−３ ｍｏｌ／Ｌ、ＣＴＡＢで１×１０−３〜１０×１０−３ ｍｏｌ／Ｌとしているが、これは導電体のキャリア極性の制御や熱電特性の最適化を目的として選んだ濃度である。
他の界面活性剤又は荷電特性制御化合物では、溶媒の種類、溶解度によって適切な熱電特性になる様にモル濃度を制御すればよい。本発明では、適切な熱電特性になる様にSeebeck係数と導電率を調整されたグラファイト集積膜を、熱電変換層と呼ぶことにする。
In Examples described later, the molar concentration of the aqueous solution of the surfactant used is, 1 × 10 -3 ~500 × with DBS 10 -3 mol / L, 1 × 10 in CTAB -3 ~10 × 10 -3 mol / L However, this is the concentration selected for the purpose of controlling the carrier polarity of the conductor and optimizing the thermoelectric properties.
For other surfactants or charge property control compounds, the molar concentration may be controlled so as to obtain appropriate thermoelectric properties depending on the type and solubility of the solvent. In the present invention, a graphite integrated film whose Seebeck coefficient and conductivity have been adjusted so as to have appropriate thermoelectric characteristics will be referred to as a thermoelectric conversion layer.
本発明のグラファイト集積膜は、グラファイト薄片表面に微量存在する界面活性剤等の荷電特性を制御可能な化合物によるフォノン散乱は小さく、市販のヒートシンクに利用されるアルミニウムの熱伝導率（室温で２３６Ｗ／ｍＫ）以上の高い熱伝導率を有し、当該グラファイト集積膜を市販のグラファイトシートと接合した場合においても、グラファイトシートの８０％以上の熱伝導率を有するため、放熱材として使用することができる。
また、本発明のグラファイト集積膜は、界面活性剤等の荷電特性を制御可能な化合物とグラファイトの間の電荷移動により、適切なキャリア濃度を持たせることが可能となる。
したがって、用いる界面活性剤等の荷電特性を制御可能な化合物の種類や濃度を変えてＰ型Ｎ型のキャリアタイプやキャリア濃度を制御してSeebeck係数を制御した２種類のグラファイト集積膜の一端を接合し、その接合部分ともう片方の端との温度差をSeebeck効果によって熱起電力に変換することにより、接合部分の温度を計測することができ、熱電対機能付放熱材として使用できる。
このように、本発明のグラファイト集積膜の放熱と温度計測の機能は、２種類の互いにSeebeck係数の異なるグラファイト集積膜の１端を接合した１枚の膜で実現でき、接合部に発熱部品を設置するだけで発熱部品の温度計測と放熱を同時に行うことができ、さらに、放熱を行いながら、熱電変換により発電を行うことも可能であり、１つの部材で発熱部を冷却しながら微小電源としても機能する。
In the graphite integrated film of the present invention, phonon scattering by a compound capable of controlling charge characteristics such as a surfactant present in a trace amount on the surface of graphite flakes is small, and the thermal conductivity of aluminum used for a commercially available heat sink (236 W / at room temperature). It has a high thermal conductivity of mK) or more, and even when the graphite integrated film is bonded to a commercially available graphite sheet, it has a thermal conductivity of 80% or more of that of the graphite sheet, so that it can be used as a heat radiating material. ..
Further, the graphite integrated film of the present invention can have an appropriate carrier concentration by the charge transfer between the graphite and a compound whose charge characteristics can be controlled such as a surfactant.
Therefore, one end of two types of graphite integrated films in which the Seebeck coefficient is controlled by controlling the P-type N-type carrier type and the carrier concentration by changing the type and concentration of the compound whose charge characteristics such as the surfactant to be used can be controlled. By joining and converting the temperature difference between the joined portion and the other end into thermoelectromotive force by the Seebeck effect, the temperature of the joined portion can be measured and it can be used as a heat radiating material with a thermocouple function.
As described above, the functions of heat dissipation and temperature measurement of the graphite integrated membrane of the present invention can be realized by one membrane in which one end of two types of graphite integrated membranes having different Seebeck coefficients are joined to each other, and a heat generating component is provided at the joint. It is possible to measure the temperature of heat-generating parts and dissipate heat at the same time just by installing it, and it is also possible to generate power by thermoelectric conversion while dissipating heat. Also works.
また、本発明のグラファイト集積膜においては、別途、熱伝導性に優れた酸化グラフェン集積膜を、絶縁膜又は絶縁層として併用することで、熱伝導率の低下を抑制しながら、熱電対構造の作製や、吸熱対象物との電気的絶縁性を確保することができる。酸化グラフェンは、グラフェンにエポキシ基、カルボキシル基、カルボニル基、水酸基など様々な酸素含有官能基が結合したものである。本発明において十分な電気絶縁性及び熱伝導性を示すための酸素濃度は２０〜４０％の範囲が望ましく、その際の酸化グラフェンの単片の面内方向の大きさ（粒径）としては、１μｍ以上であることが望ましく、２μｍ以上であることがより望ましい。加えて、単片の厚さにして０．７〜１．５ｎｍのサイズを持つものが望ましい。この単片を多数堆積し、１〜４０μｍの範囲の厚さを持つ集積膜にしたものを、酸化グラフェン集積膜として用いることができる。 Further, in the graphite integrated film of the present invention, by separately using a graphene oxide integrated film having excellent thermal conductivity as an insulating film or an insulating layer, a thermocouple structure can be obtained while suppressing a decrease in thermal conductivity. It can be manufactured and its electrical insulation from the heat-absorbing object can be ensured. Graphene oxide is graphene to which various oxygen-containing functional groups such as an epoxy group, a carboxyl group, a carbonyl group, and a hydroxyl group are bonded. In the present invention, the oxygen concentration for exhibiting sufficient electrical insulation and thermal conductivity is preferably in the range of 20 to 40%, and the in-plane size (particle size) of a single piece of graphene oxide at that time is defined. It is preferably 1 μm or more, and more preferably 2 μm or more. In addition, it is desirable that the thickness of the single piece has a size of 0.7 to 1.5 nm. A large number of these single pieces are deposited to form an integrated film having a thickness in the range of 1 to 40 μm, which can be used as a graphene oxide integrated film.
以下、図面を用いて、本発明のグラファイト集積膜の、放熱材としての利用、熱電対機能付放熱材としての利用、及び熱発電する放熱材としての利用について、それぞれ例示するとともに、本発明のグラファイト集積膜を用いた効果について記載する。 Hereinafter, with reference to the drawings, the use of the graphite integrated film of the present invention as a heat radiating material, the use as a heat radiating material with a thermocouple function, and the use as a heat radiating material for thermoelectric generation will be illustrated, and the present invention will be described. The effect of using the graphite integrated film will be described.
（放熱材としての利用）
図２（ａ）は、本発明のグラファイト集積膜の、電気絶縁性を持つ放熱材としての利用について説明する図であり、図中、１は、本発明のグラファイト集積膜を示し、２は、導電性を有しない酸化グラフェン集積膜を示している。（ａ）に示すように、本発明のグラファイト集積膜の両表面に、酸化グラフェン集積膜（２）を被覆することにより電気絶縁性を付与したものは、熱は伝えるが、電気は伝えないため、放熱材として、又は熱界面材料として利用することができ、パワー半導体・電子部品・電池の冷却に好適である。
（ｂ）及び（ｃ）は、それぞれ、放熱材及び熱界面材料（ＴＩＭ）としての利用例を示すものであり、図中、矢印は、熱流を示し、３は、放熱対象物（発熱体又は熱源）を示し、４は、ヒートシンクを示している。
(Use as a heat dissipation material)
FIG. 2A is a diagram illustrating the use of the graphite integrated film of the present invention as a heat radiating material having electrical insulating properties. In the figure, 1 indicates the graphite integrated film of the present invention, and 2 indicates the graphite integrated film of the present invention. It shows a graphene oxide integrated film that does not have conductivity. As shown in (a), the graphite integrated film of the present invention to which electrical insulation is imparted by coating both surfaces of the graphite integrated film (2) transmits heat but not electricity. It can be used as a heat radiating material or as a thermal interface material, and is suitable for cooling power semiconductors, electronic parts, and batteries.
(B) and (c) show examples of use as a heat radiating material and a thermal interface material (TIM), respectively. In the figure, arrows indicate heat flows, and 3 is a heat radiating object (heating element or heating element or). Heat source), and 4 indicates a heat sink.
（熱電対機能付放熱材としての利用）
図３は、本発明のグラファイト集積膜の、熱電対機能付き放熱材の設計例を示す図であり、図中、２は、導電性を有しない酸化グラフェン集積膜を、５は、熱電変換層を、６は、５とはSeebeck係数の異なる熱電変換層を、７は、５と６の接合部、８は、測温部、９は、計測端子部を、それぞれ示しており、熱電変換層（５）及び熱電変換層（６）の少なくとも一方に、本発明のグラファイト集積膜を使用するものである。
熱電対機能付き放熱材の断面図として、（ａ）に示すように、熱電変換層（５）及び熱電変換層（６）を、測温部（８）である一部の接合部（７）を残して、導電性のない酸化グラフェン集積膜（２）を介して接合し、放熱材とする。
熱電対機能付き放熱材の形状は、特に限定されないが、（ｂ）に、円形放熱材の例を、（ｃ）に、長方形放熱材の例を、それぞれ示している。（ｂ）及び（ｃ）はいずれも、熱電対機能付き放熱材の面に垂直な方向で、熱電変換層５を上にした形で見た図を示している。
(Use as a heat radiating material with a thermocouple function)
FIG. 3 is a diagram showing a design example of a heat radiating material with a thermocouple function of the graphite integrated film of the present invention. In the figure, 2 is a graphene oxide integrated film having no conductivity, and 5 is a thermoelectric conversion layer. 6 indicates a thermoelectric conversion layer having a Seebeck coefficient different from that of 5, 7 indicates a junction between 5 and 6, 8 indicates a temperature measuring unit, and 9 indicates a measuring terminal unit. The graphite integrated film of the present invention is used for at least one of (5) and the thermoelectric conversion layer (6).
As a cross-sectional view of the heat radiating material with a thermocouple function, as shown in (a), the thermoelectric conversion layer (5) and the thermoelectric conversion layer (6) are combined with a part of the joint (7) which is a temperature measuring part (8). Is joined via a non-conductive graphene oxide integrated film (2) to form a heat radiating material.
The shape of the heat radiating material with a thermocouple function is not particularly limited, but (b) shows an example of a circular heat radiating material, and (c) shows an example of a rectangular heat radiating material. Both (b) and (c) show a view in a direction perpendicular to the surface of the heat radiating material with a thermocouple function, with the
図４は、前記図３に示した熱電対機能付き放熱材を、放熱・測温対象部品に使用する例を示すものであり、図中、２は、酸化グラフェン集積膜を、３は、放熱・測温対象物を、７は、接合部、８は、測温部、９は、端部に設けられた計測端子部を、矢印は、熱流を示している。
（ａ）に示すように、本発明の熱電対機能付き放熱材の接合部（７）の上部に、放熱・測温対象部品（３）を設置した場合も、従来どおりの放熱機能を維持している。
（ｂ）は、放熱しながら、放熱対象物の温度を計測する例を示しており、計測端子部（９）における熱起電力ΔＶを計測することにより、接合部（７）（及び測温部（８））の温度Ｔ１と計測端子部（９）の温度Ｔ２の温度差ΔＴ＝Ｔ１−Ｔ２を計測することができ、放熱対象物（３）から放熱材を流れる熱流密度も計測可能である。
また、（ｃ）に示す例は、前記図３に記載した酸化グラフェン集積膜（２）などの電気絶縁膜と組み合わせることで、放熱対象物が電子部品の場合の、電気的な信号の干渉及びそれによる温度計測データへのノイズ混入を防ぐことを可能にしたものである。
FIG. 4 shows an example in which the heat radiating material with a thermocouple function shown in FIG. 3 is used for a component subject to heat dissipation and temperature measurement. In the figure, 2 is a graphene oxide integrated film and 3 is heat dissipation. -The temperature measurement object, 7 is a joint portion, 8 is a temperature measurement portion, 9 is a measurement terminal portion provided at an end portion, and an arrow indicates a heat flow.
As shown in (a), even when the heat dissipation / temperature measurement target component (3) is installed above the joint portion (7) of the heat dissipation material with a thermocouple function of the present invention, the conventional heat dissipation function is maintained. ing.
(B) shows an example of measuring the temperature of the object to be radiated while radiating heat, and by measuring the thermothermal force ΔV at the measurement terminal portion (9), the joint portion (7) (and the temperature measuring portion) (8)) temperatures T 1 and the measurement terminal portion a temperature difference ΔT = T 1 -T 2 of the temperature T 2 of the (9) can be measured, and also the heat flow density through the heat radiating member from the heat radiating object (3) It is measurable.
Further, the example shown in (c) can be combined with an electric insulating film such as the graphene oxide integrated film (2) shown in FIG. 3 to cause electrical signal interference and electrical signal interference when the heat radiation object is an electronic component. This makes it possible to prevent noise from being mixed into the temperature measurement data.
計測端子部における熱起電力ΔＶは、
したがって、図５に示すように、計測端子部の温度Ｔ２が既知で一定、又はΔＴが同じ場所なら、どこにΔＶ計測端子をつないでも、同じΔＶが得られ、部品形状の自由度がある。
The thermoelectromotive force ΔV at the measurement terminal is
Therefore, as shown in FIG. 5, if the temperature T 2 of the measurement terminal portion is known and constant, or if the ΔT is the same, the same ΔV can be obtained no matter where the ΔV measurement terminal is connected, and there is a degree of freedom in the shape of the component.
図６は、本発明のグラファイト集積膜を用いた熱電対機能付き放熱材の、他の設計・使用例を断面図として示すものであり、前図３及び前図４と同様に、図中、３は、放熱・測温対象物を示し、５は、熱電変換層を、６は、５とはSeebeck係数の異なる熱電変換層を、７は、接合部を示し、矢印は、熱流を示している。
（ａ）に示すように、放熱・測温対象物（３）から、１対の接合による熱起電力を測定してもよいし、（ｂ）に示すように、放熱・測温対象部品（３）から、ｎ対の接合を複数直列にして、合計の熱起電力（測温感度）を向上させて測定してもよい。
FIG. 6 shows another design / use example of the heat radiating material with a thermocouple function using the graphite integrated film of the present invention as a cross-sectional view. 3 indicates a heat dissipation / temperature measurement object, 5 indicates a thermoelectric conversion layer, 6 indicates a thermoelectric conversion layer having a Seebeck coefficient different from that of 5, 7 indicates a joint portion, and an arrow indicates a heat flow. There is.
As shown in (a), the thermoelectromotive force due to a pair of joints may be measured from the heat dissipation / temperature measurement target object (3), or as shown in (b), the heat dissipation / temperature measurement target component ( From 3), a plurality of n pairs of junctions may be connected in series to improve the total thermoelectromotive force (temperature measurement sensitivity) for measurement.
（熱発電する放熱材としての利用）
図７は、本発明のグラファイト集積膜の、熱発電する放熱材の設計例を断面図として示す図であり、図中、２は、導電性を有しない酸化グラフェン集積膜を、５は、熱電変換層を、６は、５とはSeebeck係数の異なる熱電変換層を、７は、接合部、１０は、負荷（抵抗Ｒ）を、それぞれ示しており、熱電変換層（５）及び熱電変換層（６）の少なくとも一方に、本発明のグラファイト集積膜を使用するものである。
この例では、熱電変換層（Seebeck係数ＳＰ）（５）と、熱電変換層（Seebeck係数ＳＮ）（６）を用い、端部の接合部（７）を除き、導電性のない酸化グラフェン集積膜（２）を介在させたものを用いている。
（ａ）は、その１対の熱発電素子の例であり、最大出力電力は、
また、（ｂ）は、そのｎ対の熱発電素子の例であり、最大出力電力は、
FIG. 7 is a cross-sectional view showing a design example of a heat radiating material for heat power generation of the graphite integrated film of the present invention. In the figure, 2 is a graphene oxide integrated film having no conductivity, and 5 is thermoelectric. The conversion layer, 6 indicates a thermoelectric conversion layer having a different Seebeck coefficient from 5, 7, 7 indicates a junction, and 10 indicates a load (resistance R), respectively, and the thermoelectric conversion layer (5) and the thermoelectric conversion layer. The graphite integrated film of the present invention is used for at least one of (6).
In this example, the thermoelectric conversion layer (Seebeck coefficient S P) (5), the thermoelectric conversion layer (Seebeck coefficient S N) (6) used, except the junction of the end portion (7), nonconductive graphene oxide The one with the integrated membrane (2) intervened is used.
(A) is an example of the pair of thermoelectric generators, and the maximum output power is
Further, (b) is an example of the n pairs of thermoelectric power generation elements, and the maximum output power is
図８は、前記図７に示した熱発電する放熱材の使用例を断面図として示す図であり、放熱フィンを兼ねた熱発電素子を示すものであり、図中、３は、熱源、４は、ヒートシンク、１０は、負荷、１１は、放熱フィン、矢印は、熱流を、それぞれ示している。
この例では、放熱フィン（１１）を兼ねた熱発電素子を介して、熱源（放熱対象物）（３）から放熱をしながら、発電も行うことが可能である。
FIG. 8 is a cross-sectional view showing an example of using the heat-generating heat-generating material shown in FIG. 7, showing a heat-generating element that also serves as a heat-dissipating fin. Indicates a heat sink, 10 indicates a load, 11 indicates a heat dissipation fin, and an arrow indicates a heat flow.
In this example, it is possible to generate electricity while dissipating heat from the heat source (heat dissipation object) (3) via the thermoelectric generation element that also serves as the heat dissipation fin (11).
以下、本発明を実施例により具体的に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.
（グラファイト集積膜の製造）
グラファイトを分散する前の界面活性剤水溶液のモル濃度は、水溶液全体の容積に対して所定のモル濃度になるように界面活性剤の量を電子天秤（アズワン製IUZ-101型）で秤量したのち、それを１００ｍＬビーカー内の精製水に投入し、スターラー（アズワン製RS-1AR型）を用いて室温にて毎分１０００回転で回転子を約３分間回して溶解することで調節した。
(Manufacturing of graphite integrated film)
The molar concentration of the aqueous surfactant solution before dispersing graphite is determined by weighing the amount of the surfactant with an electronic balance (IUZ-101 type manufactured by AS ONE) so that the molar concentration becomes a predetermined molar concentration with respect to the volume of the entire aqueous solution. , It was put into purified water in a 100 mL beaker, and adjusted by rotating the rotor at 1000 rpm at room temperature for about 3 minutes using a stirrer (RS-1AR type manufactured by AS ONE).
図９に示すように、薄片化したグラファイト粉末（アイテック社製、iGrafen-a、粒子径最大１００μｍ、平均厚さ約１０ｎｍ）１８０ｍｇを、前記の界面活性剤の水溶液４０ｍＬに投入し、超音波洗浄器（アズワン製USK-1R型）で３０分程度超音波を印加して分散処理を行うことにより、グラファイト薄片の表面を界面活性剤の水溶液で被覆した。
その後、このグラファイト分散液を孔径１０μｍのPTFEメンブレン（Omnipore製JCWP04700）で濾過し、メンブレンを除去した直径４０ｍｍの積層体を２５〜７０℃のホットプレート（アズワン製HI-1000型）上で２〜６時間静置・乾燥して水分を除去した。この積層体に、小型熱プレス機（アズワン製AH-2003型）を用いて２５〜１００℃で１０トンのプレス処理を施すことにより、直径４０ｍｍ・厚さ約７０〜９０μｍのグラファイト集積膜を得た。（以下、得られたグラファイト集積膜を「ＤＢＳ添加グラファイト集積膜」ということもある。）
As shown in FIG. 9, 180 mg of flaky graphite powder (iGrafen-a manufactured by Aitec,
Then, this graphite dispersion is filtered through a PTFE membrane (JCWP04700 manufactured by Omnipore) having a pore size of 10 μm, and the laminated body having a diameter of 40 mm from which the membrane has been removed is placed on a hot plate (HI-1000 type manufactured by AS ONE) at 25 to 70 ° C. for 2 to 2 It was allowed to stand for 6 hours and dried to remove water. A graphite integrated film having a diameter of 40 mm and a thickness of about 70 to 90 μm is obtained by pressing 10 tons of this laminate at 25 to 100 ° C. using a small heat press machine (AH-2003 type manufactured by AS ONE). It was. (Hereinafter, the obtained graphite integrated film may be referred to as "DBS-added graphite integrated film".)
上記の例では、分散した界面活性剤を陰イオン系のＤＢＳ（ドデシルベンゼンスルホン酸、関東化学製24023-32）の水溶液を用いているが、本実施例ではこの他に、陽イオン系のＣＴＡＢ（臭化ヘキサデシルトリメチルアンモニウム、和光純薬工業製036-02102）の水溶液を用いた集積膜、さらにはこれらの界面活性剤を用いずに成膜したグラファイト集積膜を電気物性の比較のために作製した。 In the above example, an aqueous solution of an anionic DBS (dodecylbenzene sulfonic acid, 24023-32 manufactured by Kanto Chemical Co., Inc.) is used as the dispersed surfactant, but in this example, in addition to this, a cationic CTAB is used. An integrated film using an aqueous solution of (hexadecyltrimethylammonium bromide, 036-02102 manufactured by Wako Pure Chemical Industries, Ltd.) and a graphite integrated film formed without using these surfactants are used for comparison of electrical properties. Made.
本実施例で用いた界面活性剤のモル濃度は、ＤＢＳで１×１０−３ ｍｏｌ／Ｌ〜５００×１０−３ ｍｏｌ／Ｌ、ＣＴＡＢで１×１０−３ ｍｏｌ／Ｌ〜１０×１０−３ ｍｏｌ／Ｌとしたが、これは導電体のキャリア極性の制御や熱電特性の最適化を目的として選んだ濃度である。他の界面活性剤では、溶媒の種類、溶解度によって適切な熱電特性になる様に濃度を制御すればよい。 Molar concentration of the surfactant used in this example, DBS at 1 × 10 -3 mol / L~500 × 10 -3 mol / L, 1 × 10 -3 mol / L~10 × 10 -3 in CTAB Although it was set to mol / L, this is a concentration selected for the purpose of controlling the carrier polarity of the conductor and optimizing the thermoelectric characteristics. For other surfactants, the concentration may be controlled so as to obtain appropriate thermoelectric characteristics depending on the type and solubility of the solvent.
（走査型電子顕微鏡観察）
図１０は、得られたＤＢＳ添加グラファイト集積膜を、走査型電子顕微鏡（ＳＥＭ、日立ハイテクノロジーズ製S-4800型）を用いて撮影したＳＥＭ写真であり、（ａ）は、表面を撮影したもの、（ｂ）は、断面を撮影したものである。
ＳＥＭ写真に示すように、ＤＢＳ添加グラファイト集積膜の表面及び断面はいずれも、グラファイト薄片が隙間なく敷き詰められた積層体を形成している様子がわかる。緻密な集積膜であることは、この膜の密度が１．９５ｇ／ｃｍ３でグラファイト結晶の密度２．２ｇ／ｃｍ３の８５％以上を有していることからも示された。
(Scanning electron microscope observation)
FIG. 10 is an SEM photograph of the obtained DBS-added graphite integrated film taken with a scanning electron microscope (SEM, Hitachi High-Technologies S-4800 type), and FIG. 10A is a photograph of the surface. , (B) are photographs of the cross section.
As shown in the SEM photograph, it can be seen that both the surface and the cross section of the DBS-added graphite integrated film form a laminate in which graphite flakes are spread without gaps. It is a dense integrated film, the density of the film was also shown since it has a more than 85% of the density of 2.2 g / cm 3 of graphite crystals in 1.95 g / cm 3.
（Ｘ線回折パターン及びラマンスペクトル）
図１１は、Ｘ線回折測定装置（Rigaku製UltimaIV/PSK型）を用いて測定した、ＤＢＳ添加グラファイト集積膜（ａ）及び市販のグラファイトシート（ｂ）のＸ線回折パターンである。
また、図１２は、ラマン顕微鏡（Horiba製XploLA型）を用いて測定した、ＤＢＳ添加グラファイト集積膜（ａ）及び市販のグラファイトシート（ｂ）のラマンスペクトルである。
いずれも、純粋な市販のグラファイトシートと同様のパターン及びスペクトルを示した。これは、分散溶液中で超音波印加しても、グラファイト薄片に大きな欠陥は生じていないことを示している。
(X-ray diffraction pattern and Raman spectrum)
FIG. 11 is an X-ray diffraction pattern of the DBS-added graphite integrated film (a) and the commercially available graphite sheet (b) measured using an X-ray diffraction measuring device (Ultima IV / PSK type manufactured by Rigaku).
Further, FIG. 12 is a Raman spectrum of the DBS-added graphite integrated film (a) and the commercially available graphite sheet (b) measured using a Raman microscope (XploLA type manufactured by Horiba).
Both showed patterns and spectra similar to pure commercial graphite sheets. This indicates that even when ultrasonic waves were applied in the dispersion solution, no major defects were generated in the graphite flakes.
（界面活性剤の有無・極性と、得られた集積膜の電気物性との関係）
界面活性剤の有無及び界面活性剤分子の極性と、界面活性剤で被覆したグラファイト集積膜の電気物性（Seebeck係数、導電率、パワーファクター、Hall係数、磁気抵抗）の関係を調べた。
(Relationship between the presence / polarity of the presence / absence of a surfactant and the electrical properties of the obtained integrated film)
The relationship between the presence or absence of a surfactant, the polarity of the surfactant molecule, and the electrical properties (Seebeck coefficient, conductivity, power factor, Hall coefficient, magnetoresistance) of the graphite integrated film coated with the surfactant was investigated.
最初に、グラファイト集積膜のSeebeck係数、導電率、Hall係数、磁気抵抗の測定について説明する。 First, the measurement of Seebeck coefficient, conductivity, Hall coefficient, and magnetoresistance of the graphite integrated film will be described.
Seebeck係数及び導電率の測定は次のように行なった。
幅約３ｍｍ長さ約２０ｍｍの短冊状に切り出した集積膜試料を、試料の片側が加熱できるようにした試料ステージに設置し、試料の長手方向の両端に電流供給用の端子２個、及び試料内２点間の温度差及び電位差測定用のＲ型熱電対２本を、試料に電気的・熱的に接触させた。その後、試料の片側をヒータで加熱した時の、試料内２点間の温度差をデジタルマルチメータ（ケースレーインスツルメンツ製2700型）で、Ｒ型熱電対の白金電極側での電位差をナノボルトメータ（キーサイトテクノロジー製34420A型）で測定した。試料内２点間の温度差を０〜２Ｋの間で３点以上変えて与え、それらの温度差に対する電位差の傾きを求めて熱起電力を算出し、その値から白金電極のSeebeck係数を差し引くことで、試料のSeebeck係数を算出した。
The Seebeck coefficient and conductivity were measured as follows.
An integrated film sample cut into a strip with a width of about 3 mm and a length of about 20 mm is placed on a sample stage where one side of the sample can be heated, and two terminals for supplying current and the sample are provided at both ends in the longitudinal direction of the sample. Two R-type thermocouples for measuring the temperature difference and potential difference between the two points were electrically and thermally contacted with the sample. After that, when one side of the sample is heated with a heater, the temperature difference between two points in the sample is measured by a digital multimeter (Keithley Instruments 2700 type), and the potential difference of the R-type thermocouple on the platinum electrode side is measured by a nanovolt meter (Nanovoltmeter). Measured with Keysight Technology 34420A). The temperature difference between 2 points in the sample is changed by 3 points or more between 0 and 2K, the gradient of the potential difference with respect to those temperature differences is calculated, the thermoelectromotive force is calculated, and the Seebeck coefficient of the platinum electrode is subtracted from that value. Therefore, the Seebeck coefficient of the sample was calculated.
導電率は、直流電流源（エーディーシー製6242型）を用いて電流供給用端子を通じて試料に約１００ｍＡ以下の電流を流しながら、試料内２点間の電位差を同型のデジタルマルチメータで測定し、４端子法によって求めた。 The conductivity is measured by measuring the potential difference between two points in the sample with a digital multimeter of the same type while passing a current of about 100 mA or less through the current supply terminal using a DC current source (ADC 6242 type). It was obtained by the 4-terminal method.
また、Hall係数、磁気抵抗は導電率と共に次のように行なった。
１辺約１０ｍｍの正方形に切り出した集積膜試料を、ホール計測システム（東陽テクニカ製Resitest 8300型）にセットし、van der Pauw法を用いて導電率、Hall係数、磁気抵抗測定した。この際に印加した磁場は最大０．５５Ｔとした。Seebeck係数計測時及びHall係数計測時の２つの導電率が互いに１０％以内の精度で一致していることを確認した。Seebeck係数、導電率、Hall係数、磁気抵抗の測定はいずれも室温でのみ測定した。
The Hall coefficient and magnetoresistance were calculated together with the conductivity as follows.
An integrated membrane sample cut into a square with a side of about 10 mm was set in a Hall measurement system (Resitest 8300 type manufactured by Toyo Technica), and conductivity, Hall coefficient, and magnetoresistance were measured using the van der Pauw method. The maximum magnetic field applied at this time was 0.55 T. It was confirmed that the two conductivitys at the time of measuring the Seebeck coefficient and the time of measuring the Hall coefficient match each other with an accuracy of 10% or less. The Seebeck coefficient, conductivity, Hall coefficient, and magnetoresistance were all measured only at room temperature.
図１３に、陰イオン系の界面活性剤ＤＢＳ水溶液を用いた集積膜、陽イオン系の界面活性剤ＣＴＡＢ水溶液を用いた集積膜、及び界面活性剤を用いずに成膜した集積膜の、Seebeck係数、導電率、Hall係数、磁気抵抗を測定した結果を示す。パワーファクターは、以下のとおりSeebeck係数と導電率の値を用いて算出した。
パワーファクター＝（Seebeck係数）２×導電率
FIG. 13 shows Seebeck of an integrated film using an anionic surfactant DBS aqueous solution, an integrated film using a cationic surfactant CTAB aqueous solution, and an integrated film formed without using a surfactant. The results of measuring the coefficient, conductivity, Hall coefficient, and magnetic resistance are shown. The power factor was calculated using the Seebeck coefficient and conductivity values as follows.
Power factor = (Seebeck coefficient) 2 x conductivity
図１３に示す結果から、特筆すべき点として、
（１）陽イオン系界面活性剤→界面活性剤なし→陰イオン系界面活性剤の順に、Seebeck係数及びHall係数の符号が負から正の方向に変化していること、
（２）界面活性剤なしの場合にSeebeck係数とHall係数の符号が異なること、（３）すべての試料で磁気抵抗がゼロでないこと、
の３点が指摘できる。
（２）及び（３）は、グラファイト集積膜の電気伝導には正孔と電子の両方が寄与している半金属的物性であることを意味する。加えて（１）で示されたとおり、界面活性剤の極性を変えることで、界面活性剤分子とグラファイト表面の間の電荷移動により、電気伝導を担う正孔と電子の濃度のバランス（差）をわずかに変化させ、Seebeck係数とHall係数の符号を変化させている。本実験で用いた濃度範囲では、導電率に対する界面活性剤の有無や種類への依存性は小さく、そのためにSeebeck係数の比較的大きなＤＢＳを用いた集積膜のパワーファクター（熱電発電性能）が、界面活性剤を用いない場合やＣＴＡＢを用いた集積膜より数倍以上高い値を示した。
From the results shown in FIG. 13, it should be noted that
(1) The signs of the Seebeck coefficient and the Hall coefficient change from negative to positive in the order of cationic surfactant → no surfactant → anionic surfactant.
(2) The signs of the Seebeck coefficient and the Hall coefficient are different when no surfactant is used, and (3) the reluctance is not zero in all samples.
Can be pointed out in three points.
(2) and (3) mean that the graphite integrated film is a semimetal property in which both holes and electrons contribute to the electrical conduction. In addition, as shown in (1), by changing the polarity of the surfactant, the charge transfer between the surfactant molecule and the surface of the graphite causes the balance (difference) in the concentrations of holes and electrons that are responsible for electrical conduction. Is slightly changed, and the sign of the Seebeck coefficient and the Hall coefficient is changed. In the concentration range used in this experiment, the dependence of the presence or absence of the surfactant on the conductivity and the type is small, and therefore, the power factor (thermoelectric power generation performance) of the integrated membrane using DBS having a relatively large Seebeck coefficient is determined. The value was several times higher than that when no surfactant was used or when the integrated membrane was used with CTAB.
（ＤＢＳ濃度と電気物性との関係）
ＤＢＳ濃度（モル濃度）と、Seebeck係数、導電率、Hall係数、及び磁気抵抗との関係を調べた。
高いパワーファクターを示したＤＢＳを用いた集積膜について、水溶液中のＤＢＳ濃度と、Seebeck係数、導電率、Hall係数、及び磁気抵抗との関係を図１４に示す。
(Relationship between DBS concentration and electrical properties)
The relationship between the DBS concentration (molar concentration) and the Seebeck coefficient, conductivity, Hall coefficient, and magnetoresistance was investigated.
FIG. 14 shows the relationship between the DBS concentration in the aqueous solution, the Seebeck coefficient, the conductivity, the Hall coefficient, and the magnetoresistance of the integrated film using DBS showing a high power factor.
図１４に示すとおり、Seebeck係数は、ＤＢＳ濃度に大きな依存性を示さず、約+２０Ｖ／Ｋ以上の値で符号が正であり、正孔の相対的寄与が大きいＰ型導電体である。
導電率はＤＢＳ濃度が５０×１０−３〜１００×１０−３ ｍｏｌ／Ｌの範囲でピークを示しており、そのためにパワーファクター（熱電発電性能）は同じ濃度範囲において０．１７〜０．１８ｍＷ／ｍ・Ｋ２の最大値を示した。ＤＢＳ濃度が１００×１０−３ ｍｏｌ／Ｌ以下の範囲では、ＤＢＳ分子がグラファイト表面を被覆することで、隣り合うグラファイト薄片間の密着性（接触面積）を向上させる効果を示す一方、２００×１０−３ ｍｏｌ／Ｌ以上の範囲では過剰なＤＢＳ分子の凝集が起こり、グラファイト同士の密着性を阻害していると推測される。
以上のように、ＤＢＳ濃度によって熱電発電性能が最適化できることが分かった。
As shown in FIG. 14, the Seebeck coefficient is a P-type conductor that does not show a large dependence on the DBS concentration, has a positive sign at a value of about + 20 V / K or more, and has a large relative contribution of holes.
The conductivity peaks in the DBS concentration range of 50 × 10 -3 to 100 × 10 -3 mol / L, so the power factor (thermoelectric power generation performance) is 0.17 to 0.18 mW in the same concentration range. The maximum value of / m · K 2 was shown. When the DBS concentration is in the range of 100 × 10 -3 mol / L or less, the DBS molecules coat the graphite surface, which has the effect of improving the adhesion (contact area) between adjacent graphite flakes, while 200 × 10 It is presumed that excessive DBS molecule aggregation occurs in the range of -3 mol / L or more, which hinders the adhesion between graphites.
As described above, it was found that the thermoelectric power generation performance can be optimized depending on the DBS concentration.
（熱電対の作製）
以上のとおり、ＤＢＳ添加によって熱電発電性能を最大化した熱電変換層である、Ｐ型導電体のグラファイト集積膜を作ることに成功した。
そこで、本実施例では、Ｎ型で高い導電率を有することが既に知られている、純粋な市販のグラファイトシート（パナソニック製ＰＧＳグラファイトシートEYGS121803）とＰＮ接合させることにより、以下のようにして、グラファイト熱電対を作製した。
(Making a thermocouple)
As described above, we succeeded in producing a graphite integrated film of P-type conductor, which is a thermoelectric conversion layer that maximizes thermoelectric power generation performance by adding DBS.
Therefore, in this embodiment, by PN junctioning with a pure commercially available graphite sheet (PGS graphite sheet EYGS121803 manufactured by Panasonic), which is already known to have high conductivity in the N type, the following is performed. Graphite thermocouples were made.
図１５は、本実施例で製造したグラファイト熱電対を模式的に示す図であり、前記の実施例で得られたＤＢＳで被覆したグラファイト集積膜（ＤＢＳ添加グラファイト集積膜）（厚さ約７０〜９０μｍ）及び市販のグラファイトシート（厚さ約３０μｍ）を、幅４ｍｍ、長さ３０ｍｍの短冊状に加工し、いずれも片方の先端部分３〜５ｍｍの長さの領域で互いに直接接合し、それ以外の部分は電気的絶縁体である厚さ約１０〜３０μｍ（プレス前）、幅１０ｍｍ、長さ３０ｍｍの酸化グラフェン集積膜（ＧＯ膜）を挟んで接合した。
その後、先述と同型の小型熱プレス機を用いて２５〜１００℃で１〜３トンの荷重でプレス処理（熱圧着）をして、グラファイト熱電対を得た。
酸化グラフェン集積膜は、濃度４ｍｇ／ｍＬの酸化グラフェン（Graphenea社製）水分散液２０〜３０ｍＬを、８０℃で２時間以上乾燥させて得た膜である。
FIG. 15 is a diagram schematically showing the graphite thermocouple produced in this example, and is a graphite integrated film (DBS-added graphite integrated film) (thickness about 70 to about 70 to) coated with DBS obtained in the above example. 90 μm) and a commercially available graphite sheet (thickness about 30 μm) are processed into strips with a width of 4 mm and a length of 30 mm, both of which are directly joined to each other in a region having a length of 3 to 5 mm at one tip, and the other. This part was joined by sandwiching a graphite oxide integrated film (GO film) having a thickness of about 10 to 30 μm (before pressing), a width of 10 mm, and a length of 30 mm, which is an electrical insulator.
Then, a graphite thermocouple was obtained by press treatment (thermocompression bonding) at 25 to 100 ° C. with a load of 1 to 3 tons using a small heat press machine of the same type as described above.
The graphene oxide integrated membrane is a membrane obtained by drying 20 to 30 mL of a graphene oxide (manufactured by Graphenea) aqueous dispersion having a concentration of 4 mg / mL at 80 ° C. for 2 hours or more.
なお、上記実施例では、Ｎ型導電体として、グラファイトシートを用いた例を示しているが、ＣＴＡＢ等の陽イオン系界面活性剤で被覆したグラファイト集積膜（熱電変換層）を用いることもできることは言うまでもない。 In the above embodiment, a graphite sheet is used as the N-type conductor, but a graphite integrated film (thermoelectric conversion layer) coated with a cationic surfactant such as CTAB can also be used. Needless to say.
このグラファイト熱電対では、直接ＰＮ接合された先端部分が測温部となり、その測温部ともう片方の端との間（シートの面内方向）で温度差を付与することにより、熱起電力を発生させて温度差を検知することや、熱電発電を行うことができる。 In this graphite thermocouple, the tip part directly PN-bonded becomes the temperature measuring part, and the thermoelectromotive force is applied by giving a temperature difference between the temperature measuring part and the other end (in the in-plane direction of the sheet). Can be generated to detect temperature differences and thermoelectric power generation can be performed.
本実施例で用いたＮ型の市販グラファイトシート及びＰ型のＤＢＳ添加グラファイト集積膜（熱電変換層）に対して、先述の方法によってSeebeck係数、導電率、パワーファクターを評価した。その結果を、表１に示す。 The Seebeck coefficient, conductivity, and power factor of the N-type commercially available graphite sheet and the P-type DBS-added graphite integrated film (thermoelectric conversion layer) used in this example were evaluated by the above-mentioned methods. The results are shown in Table 1.
図１６に、グラファイト集積膜を熱電対に用いた温度計測の結果を示す。図中、ΔTは、熱電対測温の加熱用ヒータの温度と周囲温度の差、ΔＶは、グラファイト熱電対から発生した熱起電力をそれぞれ表している。
計測は次のように行った。グラファイト熱電対の測温部近傍に局所加熱用ヒータとＫ型熱電対（以下、「ヒータ用熱電対」と呼ぶ）を接触させてヒータで加熱し、その際のヒータ用熱電対の温度と室温（周囲温度）の差ΔＴをデジタルマルチメータ（ケースレーインスツルメンツ製2700型）で計測し、並行してグラファイト熱電対の熱起電力ΔＶをナノボルトメータ（ケースレーインスツルメンツ製2182A型）で測定した。
その結果、図１６（ａ）に示すように、ΔＴに応じてΔＶが変化することが分かり、熱電対として機能していることを確認した。
さらに、図１６（ｂ）に示すように、本実施例のグラファイト熱電対は、温度差ΔＴ＝４３．４Ｋでの応答性を規格化すると、Ｋ型薄膜熱電対よりも早い応答性を示すことが分かった。
FIG. 16 shows the results of temperature measurement using a graphite integrated film as a thermocouple. In the figure, ΔT represents the difference between the temperature of the heating heater for thermocouple temperature measurement and the ambient temperature, and ΔV represents the thermoelectromotive force generated from the graphite thermocouple.
The measurement was performed as follows. A local heating heater and a K-type thermocouple (hereinafter referred to as "heater thermocouple") are brought into contact with each other near the temperature measuring part of the graphite thermocouple and heated by the heater, and the temperature and room temperature of the heater thermocouple at that time. The difference ΔT of (ambient temperature) was measured with a digital multimeter (Caseray Instruments 2700 type), and in parallel, the thermoelectromotive force ΔV of the graphite thermocouple was measured with a nanovolt meter (Caseray Instruments 2182A type).
As a result, as shown in FIG. 16A, it was found that ΔV changed according to ΔT, and it was confirmed that it functions as a thermocouple.
Further, as shown in FIG. 16B, the graphite thermocouple of this example exhibits a faster responsiveness than the K-type thin film thermocouple when the responsiveness at a temperature difference ΔT = 43.4K is standardized. I understood.
グラファイト熱発電素子は、図１５と同様の構造として形成される。図１７に、幅４ｍｍ、長さ３０ｍｍの短冊状グラファイト熱発電素子の測温部と周囲温度との間に温度差ΔＴ＝４３．４Ｋを与えた場合の、電圧電流特性及び熱電発電出力Poutの値を示す。
電圧電流特性はソースメータ（ケースレーインスツルメンツ製2400型）を用いて、最大１ｍＡの直流電流を供給して測定した。
この熱発電素子では、Ｐ型導電体をＤＢＳ濃度が１００×１０−３ ｍｏｌ／Ｌ、パワーファクター０．１７３ｍＷ／ｍ・Ｋ２で最大化したグラファイト集積膜（熱電変換層）を用いたところ、最大出力０．１３５μＷを生じ、グラファイト熱発電素子の断面積で割ると３１μＷ／ｃｍ２の最大出力密度を生じていることが確認できた。
The graphite thermoelectric generator is formed as having the same structure as in FIG. FIG. 17 shows the voltage-current characteristics and the thermoelectric power generation output Pout when a temperature difference ΔT = 43.4K is applied between the temperature measuring part of the strip-shaped graphite thermoelectric power generation element having a width of 4 mm and a length of 30 mm and the ambient temperature. Indicates a value.
The voltage-current characteristics were measured using a source meter (Keithley Instruments 2400 type) by supplying a maximum DC current of 1 mA.
In this thermoelectric generation element, a graphite integrated film (thermoelectric conversion layer) in which a P-type conductor was maximized with a DBS concentration of 100 × 10 -3 mol / L and a power factor of 0.173 mW / m · K 2 was used. It was confirmed that a maximum output of 0.135 μW was generated, and a maximum output density of 31 μW / cm 2 was generated when divided by the cross-sectional area of the graphite thermoelectric generation element.
表２に、市販のグラファイトシート、ＤＢＳ添加グラファイト集積膜、及びこれらを接合したグラファイト熱電対の３種類に対する、膜面内方向の熱拡散率（ベテル製サーモウェーブアナライザTA33型で測定）、密度（電子天秤、アズワン製IUZ-101型で測定）、比熱（Netzch製示差走査熱量測定装置で測定）の測定結果をまとめた。測定はいずれも室温のみで行った。
膜面内方向の熱伝導率は、上記の熱拡散率、密度、比熱の３つの値の積で算出し、表２に記した。
Table 2 shows the thermal diffusivity (measured with Bethel Thermowave Analyzer TA33) and density (measured by Bethel Thermowave Analyzer TA33) for three types of commercially available graphite sheet, DBS-added graphite integrated film, and graphite thermocouple bonded to them. The measurement results of electronic balance, IUZ-101 type manufactured by AS ONE), and specific heat (measured by differential scanning calorimetry device manufactured by Netzch) are summarized. All measurements were performed at room temperature only.
The thermal conductivity in the in-plane direction of the film was calculated by multiplying the above three values of thermal diffusivity, density, and specific heat, and is shown in Table 2.
表で特筆すべき点は、ＤＢＳ添加グラファイト集積膜が、アルミニウムと同程度の高い熱伝導率（２５８Ｗ／ｍ・Ｋ）を示す点と、優れた放熱材として高い熱伝導率を示す市販のグラファイトシートと接合した後も、１０００Ｗ／ｍ・Ｋ以上の高い熱伝導率を維持している点である。 Notable points in the table are that the DBS-added graphite integrated film exhibits high thermal conductivity (258 W / m · K) comparable to that of aluminum, and commercially available graphite that exhibits high thermal conductivity as an excellent heat radiating material. Even after joining with the sheet, it maintains a high thermal conductivity of 1000 W / m · K or more.
グラファイト熱発電素子は、グラファイト熱電対と同様の構造として形成されることから、本実施例で作製したグラファイト熱電対及びグラファイト熱発電素子は、温度計測機能及び熱電発電機能を有しながら、高い熱伝導率を伴い、放熱材の機能も兼ね備える部材であることが示された。 Since the graphite thermocouple is formed as having the same structure as the graphite thermocouple, the graphite thermocouple and the graphite thermoelectric element produced in this embodiment have high heat while having a temperature measurement function and a thermoelectric power generation function. It was shown that it is a member that has conductivity and also has the function of a heat radiating material.
本発明のグラファイト集積膜は、発熱部品の温度計測と放熱の２つの機能を１つの部材で兼ね備えることができ、温度測定部位に別途、熱電対を設置する必要がないので、電気自動車や電子機器等に用いられるパワー半導体や電池等、種々の分野においての利用が期待できる。あるいは、発熱部品を冷却する放熱フィン自体が熱電発電を行ない、電力を得てセンサーや通信を自立駆動できる孤立微小電源、及びこれを利用するIoT分野にも応用できる。 The graphite integrated film of the present invention can combine the two functions of temperature measurement and heat dissipation of heat-generating parts with one member, and it is not necessary to separately install a thermocouple at the temperature measurement site, so that it is an electric vehicle or an electronic device. It can be expected to be used in various fields such as power semiconductors and batteries used for the above. Alternatively, it can also be applied to an isolated micro power source that can autonomously drive sensors and communications by obtaining power by the heat radiation fin itself that cools heat-generating parts to generate thermoelectric power, and the IoT field that uses this.
１：グラファイト集積膜
２：酸化グラフェン集積膜
３：放熱・測温対象物（発熱体又は熱源）
４：ヒートシンク
５：熱電変換層
６：５とはSeebeck係数の異なる熱電変換層
７：接合部
８：測温部
９：計測端子部
１０：負荷
１１：放熱フィン
1: Graphite integrated film 2: Graphene oxide integrated film 3: Heat dissipation / temperature measurement object (heating element or heat source)
4: Heat sink 5: Thermoelectric conversion layer 6: A thermoelectric conversion layer having a different Seebeck coefficient from 6: 5: Joint part 8: Temperature measuring part 9: Measuring terminal part 10: Load 11: Heat dissipation fin
Claims (10)
得られたグラファイト分散液を濾過後、成膜すること、
を含むグラファイト集積膜の製造方法。 Dispersing the flaky graphite powder in an aqueous solution of a compound whose charging characteristics can be controlled, and filtering the obtained graphite dispersion to form a film.
A method for producing a graphite integrated film including.
これら２つの導電体の少なくとも一方が請求項５に記載の熱電変換層で構成され、
前記絶縁体が酸化グラフェン集積膜で構成されていることを特徴とする熱電対。 Two types of conductors, a conductor composed of graphite or graphite integrated film and a conductor composed of graphite or graphite integrated film having a Seebeck coefficient different from the Seebeck coefficient of the conductor, are bonded and both conductors are joined. It is a thermocouple with an insulator interposed between them.
At least one of these two conductors is composed of the thermoelectric conversion layer according to claim 5.
A thermocouple characterized in that the insulator is composed of a graphene oxide integrated film.
これら２つの導電体の少なくとも一方が膜請求項５に記載の熱電変換層で構成され、
前記絶縁体が酸化グラフェン集積膜で構成されていることを特徴とする熱発電素子。 Two types of conductors, a conductor composed of graphite or graphite integrated film and a conductor composed of graphite or graphite integrated film having a Seebeck coefficient different from the Seebeck coefficient of the conductor, are bonded and both currents are collected. It is a thermal power generation element with an insulator interposed between the bodies.
At least one of these two conductors is composed of the thermoelectric conversion layer according to claim 5.
A thermoelectric power generation element characterized in that the insulator is composed of a graphene oxide integrated film.
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