JP2010123280A - Method of manufacturing conductor - Google Patents

Method of manufacturing conductor Download PDF

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JP2010123280A
JP2010123280A JP2008293397A JP2008293397A JP2010123280A JP 2010123280 A JP2010123280 A JP 2010123280A JP 2008293397 A JP2008293397 A JP 2008293397A JP 2008293397 A JP2008293397 A JP 2008293397A JP 2010123280 A JP2010123280 A JP 2010123280A
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graphite oxide
oxide particles
conductor
film
graphite
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JP5278739B2 (en
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Takuya Goto
拓也 後藤
Kazuyoshi Joto
和良 上等
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Mitsubishi Gas Chemical Co Inc
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a conductor greatly reducing a time required for manufacturing the conductor even when a heating treatment temperature is lower during reducing graphite oxide particles. <P>SOLUTION: The method of manufacturing the conductor with a conductive film includes a coat film forming step of forming graphite oxide particle containing liquid containing the graphite oxide particles and reducing agent into a filmed shape and then drying it to form a coat film, and a reducing step of reducing the graphite oxide particles in the coat film with heating treatment to form the conductor with the conductive film, the reducing step including a humidifying step of humidifying the coat film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、導電体の製造方法に関する。   The present invention relates to a method for manufacturing a conductor.

近年、形状の異方性が高い物質の探索、及びその応用が急速に進行している。このような物質は、多数個で他の物質との複合体にする場合には、低い添加率で高強度などの各種性能を発現すると期待されている。またその形状が極めて細い線状(1次元)や極めて薄い平面状(2次元)で、その物質が電気的に半導体または良導体であれば、単独または少数個の集合体の場合に、電子物性などに量子的な効果を発現するとも期待されている。   In recent years, the search for a material having a high shape anisotropy and its application are rapidly progressing. In the case where a large number of such substances are combined with other substances, it is expected that various properties such as high strength will be exhibited at a low addition rate. Also, if the shape is very thin linear (1D) or very thin planar (2D) and the material is an electrically semiconductor or good conductor, the physical properties can be used in the case of a single or a small number of aggregates. It is also expected to produce a quantum effect.

炭素原子を骨格とする異方性形状の平面状物質として、酸化黒鉛が知られている。酸化黒鉛は黒鉛を特定の方法により酸化することで得られる黒鉛層間化合物の一種である。酸化黒鉛は2次元的な基本層が積み重なった多層構造体であり、一般に層数は非常に多い。酸化黒鉛の基本層は、ジグザグの炭素の列で数えて炭素原子1個分または2個分の厚さの、少しsp結合の傾向のあるsp結合主体の炭素骨格と、その骨格の両側の面に結合した酸性の水酸基とを有する構造を持つと考えられている(例えば、非特許文献1〜3)。 Graphite oxide is known as an anisotropic planar material having a carbon atom as a skeleton. Graphite oxide is a kind of graphite intercalation compound obtained by oxidizing graphite by a specific method. Graphite oxide is a multilayer structure in which two-dimensional basic layers are stacked, and the number of layers is generally very large. The basic layer of graphite oxide consists of a carbon skeleton with a thickness of one or two carbon atoms counted in a zigzag carbon array and a sp 3 bond-dominant carbon skeleton with a slight tendency to sp 2 bonds, and both sides of the skeleton. It is thought that it has the structure which has the acidic hydroxyl group couple | bonded with the surface (for example, nonpatent literatures 1-3).

このような酸化黒鉛として、層数の少ない非常に薄いものも作られており(例えば、非特許文献4)、本発明者らも先に、そのような酸化黒鉛(層数が1枚の場合は例えば酸化グラフェンと呼ぶことが望ましい(グラフェンは黒鉛の1層分の名称))の薄膜状粒子を高収率で製造する方法を見出すと共に、それを還元して層数の非常に少ない黒鉛(層数が1枚の場合はグラフェンと呼ぶことが望ましい)類似の酸化黒鉛の薄膜状粒子を得たところである(特許文献1〜3)。   As such a graphite oxide, a very thin one having a small number of layers has also been made (for example, Non-Patent Document 4), and the present inventors have previously made such graphite oxide (when the number of layers is one). For example, graphene oxide (graphene is the name of one layer of graphite)) is found in a method for producing a high-yield thin film-like particle, and it is reduced to reduce the number of graphite ( When the number of layers is one, it is desirable to call it graphene.) Similar graphite oxide thin film particles have been obtained (Patent Documents 1 to 3).

こうして得られる酸化黒鉛の薄膜状粒子は、部分的に、または完全に還元されることで、黒鉛類似のsp結合の多い電子状態となり、電気伝導性が高くなることが知られている。 It is known that thin-film particles of graphite oxide thus obtained are partially or completely reduced to be in an electronic state with many sp 2 bonds similar to graphite and have high electrical conductivity.

酸化黒鉛の薄膜状粒子を使った導電体は例えば次のようにして製造される。即ちまず、薄膜状粒子の分散液単独あるいは分散液にバインダ樹脂、顔料、接着成分、増粘剤などの成分を配合したものを基体表面に塗布し、分散媒を除去することで、基体表面に塗膜を製膜する。その後、塗膜を基体から剥がし、あるいは基体ごと導電性を得るために、200℃程度以上の温度で加熱し、薄膜状粒子を還元させ、導電体を得る。この場合、塗膜あるいは基体に200℃程度以上の耐熱性が必要となってしまい、バインダ樹脂や基体の選択幅が大幅に制限され、その結果、得られる導電体の用途も制限されるおそれがある。   For example, a conductor using thin film particles of graphite oxide is manufactured as follows. That is, first, a dispersion of thin film particles alone or a mixture of a binder resin, a pigment, an adhesive component, a thickener and the like is applied to the surface of the substrate, and the dispersion medium is removed to remove the dispersion medium. A coating film is formed. Thereafter, the coating film is peeled off from the substrate, or in order to obtain conductivity with the substrate, the film is heated at a temperature of about 200 ° C. or more to reduce the thin film particles, thereby obtaining a conductor. In this case, the coating film or the substrate needs to have a heat resistance of about 200 ° C. or more, and the selection range of the binder resin and the substrate is greatly limited. As a result, the use of the obtained conductor may be limited. is there.

これを改善する方法として、予め分散液中に還元剤を添加しておく方法がある(特許文献3)。この方法では、塗膜中に存在する還元剤の効果により200℃程度以上の高温にすることなく、例えば140℃程度のより低い温度で酸化黒鉛を還元できることから、バインダ樹脂や基体の選択肢を広げることが可能である。この場合、約3時間の加熱処理によって導電体の導電性を充分なレベルにまで向上させることができる。
特開2002−53313号公報 特開2003−176116号公報 特開2005−63951号公報 「黒鉛層間化合物」,第5章,炭素材料学会編,リアライズ社(1990) T. Nakajima et al.A NEW STRUCTURE MODEL OF GRAPHITE OXIDE, Carbon,26, 357 (1988) M. Mermoux et al.FTIR AND 13C NMR STUDY OF GRAPHITE OXIDE, Carbon,29, 469 (1991) N. A. Kotov et al.Ultrathin Graphite Oxide-PolyelectrolyteComposites Prepared by Self-Assembly:Transition Between Conductive andNon-Conductive States, Adv. Mater., 8, 637 (1996)
As a method for improving this, there is a method in which a reducing agent is added to the dispersion in advance (Patent Document 3). In this method, graphite oxide can be reduced, for example, at a lower temperature of about 140 ° C. without increasing the temperature to about 200 ° C. or more due to the effect of the reducing agent present in the coating film, thereby expanding the choice of binder resin and substrate. It is possible. In this case, the electrical conductivity of the conductor can be improved to a sufficient level by the heat treatment for about 3 hours.
JP 2002-53313 A JP 2003-176116 A JP 2005-63951 A “Graphite Intercalation Compound”, Chapter 5, Carbon Society of Japan, Realize (1990) T. Nakajima et al. A NEW STRUCTURE MODEL OF GRAPHITE OXIDE, Carbon, 26, 357 (1988) M. Mermoux et al. FTIR AND 13C NMR STUDY OF GRAPHITE OXIDE, Carbon, 29, 469 (1991) NA Kotov et al. Ultrathin Graphite Oxide-PolyelectrolyteComposites Prepared by Self-Assembly: Transition Between Conductive and Non-Conductive States, Adv. Mater., 8, 637 (1996)

しかしながら、140℃の処理温度でも基体として使用できる樹脂の種類は限定されてしまうため、より低温で加熱処理を行うことが求められていた。ここで、加熱処理温度を140℃よりも低くすることで、基体として使用できるバインダ樹脂の選択幅を広げることは可能であるが、その場合には反応時間が顕著に遅くなる。例えば100℃で酸化黒鉛粒子を加熱処理する場合には、酸化黒鉛粒子を十分に還元するために10日以上の時間が必要となり、導電体を得るために多大な時間が必要となることが本発明者らの研究によって判明した。   However, since the types of resins that can be used as the substrate are limited even at a treatment temperature of 140 ° C., it has been required to perform heat treatment at a lower temperature. Here, by making the heat treatment temperature lower than 140 ° C., it is possible to widen the selection range of the binder resin that can be used as the substrate, but in that case, the reaction time is remarkably slowed. For example, when heat-treating graphite oxide particles at 100 ° C., it takes 10 days or more to fully reduce the graphite oxide particles, and it takes a lot of time to obtain a conductor. Found by the inventors' research.

上記の背景から、酸化黒鉛粒子を用いて導電体を製造する場合、酸化黒鉛粒子の還元反応において、温度に依存しない反応速度の向上方法の確立、ひいては導電体の製造に要する時間の大幅な短縮が望まれていた。   Based on the above background, when producing conductors using graphite oxide particles, establishment of a method for improving the reaction rate independent of temperature in the reduction reaction of graphite oxide particles, which in turn significantly reduces the time required for conductor production. Was desired.

本発明は上記事情に鑑みてなされたものであり、酸化黒鉛粒子を還元する際の加熱処理温度が低くても、導電体の製造に要する時間を大幅に短縮できる導電体の製造方法を提供することを目的とする。   The present invention has been made in view of the above circumstances, and provides a method for manufacturing a conductor that can significantly reduce the time required for manufacturing the conductor even when the heat treatment temperature when reducing graphite oxide particles is low. For the purpose.

本発明者らは、上記課題を解決するために鋭意研究を重ねた結果、酸化黒鉛粒子を含有する酸化黒鉛粒子含有液を基体上に塗布し乾燥してコート膜を得て、加熱処理によって酸化黒鉛粒子を還元する際に、酸化黒鉛粒子を加湿することで還元反応速度の大幅な向上が認められ、上記課題を解決しうることを見出し、本発明を完成するに至った。   As a result of intensive research to solve the above problems, the present inventors applied a graphite oxide particle-containing liquid containing graphite oxide particles on a substrate and dried to obtain a coat film, which was oxidized by heat treatment. When reducing the graphite particles, it was found that the reduction reaction rate was greatly improved by humidifying the graphite oxide particles, and the above problems could be solved, and the present invention was completed.

即ち本発明は、導電膜を備えた導電体の製造方法において、酸化黒鉛粒子及び還元剤を含有する酸化黒鉛粒子含有液をフィルム状に形成した後乾燥することによってコート膜を形成するコート膜形成工程と、前記コート膜中の前記酸化黒鉛粒子を加熱処理して還元することで前記導電膜を備えた導電体を形成する還元工程とを含み、前記還元工程が、前記コート膜を加湿する加湿工程を含む、導電体の製造方法である。   That is, the present invention relates to a method for producing a conductor having a conductive film, in which a coating film is formed by forming a graphite oxide particle-containing liquid containing graphite oxide particles and a reducing agent into a film and then drying the film. A reduction step of forming a conductor having the conductive film by heat-treating and reducing the graphite oxide particles in the coat film, wherein the reduction step humidifies the coat film. It is a manufacturing method of an electric conductor including a process.

この製造方法によれば、還元工程が、コート膜を加湿する加湿工程を含むことで、還元工程において酸化黒鉛粒子を加熱処理する場合の温度が低くても、コート膜を加湿しない場合に比べて、導電膜について十分に導電性が得られるまでの時間を大幅に短縮することができる。従って、酸化黒鉛粒子を還元する際の加熱処理温度が低くても、導電体の製造に要する時間を大幅に短縮することができる。   According to this manufacturing method, the reduction step includes a humidification step of humidifying the coating film, so that the coating film is not humidified even when the temperature when the graphite oxide particles are heat-treated in the reduction step is low. It is possible to greatly shorten the time until sufficient conductivity is obtained for the conductive film. Therefore, even if the heat treatment temperature for reducing the graphite oxide particles is low, the time required for the production of the conductor can be greatly shortened.

上記還元剤は、前記酸化黒鉛粒子含有液の乾燥前には、前記酸化黒鉛粒子中の酸素量を10質量%以上減少させず、少なくとも前記還元工程において前記酸化黒鉛粒子を還元する作用を有することが好ましい。   The reducing agent has an action of reducing the graphite oxide particles at least in the reduction step without reducing the amount of oxygen in the graphite oxide particles by 10 mass% or more before drying the graphite oxide particle-containing liquid. Is preferred.

この場合、酸化黒鉛粒子が、酸化黒鉛粒子含有液を乾燥した後の少なくとも還元工程において還元剤によって還元されるので、還元による酸化黒鉛粒子同士の分散状態の悪化を制御することができ、ひいては、酸化黒鉛粒子の含有率が低くても、より高い導電性を有する導電体を実現することができる。さらにまた、上記構成の還元剤が酸化黒鉛粒子含有液中に含まれていると、還元剤を用いない場合に比べて酸化黒鉛粒子含有液を低温で加熱しただけで酸化黒鉛粒子を還元させることができる。   In this case, since the graphite oxide particles are reduced by the reducing agent at least in the reduction step after drying the graphite oxide particle-containing liquid, it is possible to control the deterioration of the dispersion state between the graphite oxide particles due to the reduction. Even when the content of the graphite oxide particles is low, a conductor having higher conductivity can be realized. Furthermore, when the reducing agent having the above structure is contained in the graphite oxide particle-containing liquid, the graphite oxide particles can be reduced only by heating the graphite oxide particle-containing liquid at a low temperature compared to the case where the reducing agent is not used. Can do.

上記酸化黒鉛粒子は平板状であり、100nm以上の平均粒径を有し、0.4nm〜10nmの平均厚さを有することが好ましい。   The graphite oxide particles are flat, have an average particle diameter of 100 nm or more, and preferably have an average thickness of 0.4 nm to 10 nm.

この場合、酸化黒鉛における基本層の層数が非常に少なく、平均厚さが薄いことで還元が容易であり、また形状異方性が顕著に高く、そのため導電膜に導電性を発現させるために必要な導電膜中の酸化黒鉛粒子の含有率を低減することが可能になる。このため、導電膜について高い透明性が得られるとともに、得られる導電膜からの酸化黒鉛粒子の脱離を顕著に抑制できる。   In this case, the number of basic layers in graphite oxide is very small, the average thickness is thin, and reduction is easy, and the shape anisotropy is remarkably high, so that the conductive film can exhibit conductivity. It becomes possible to reduce the required content of graphite oxide particles in the conductive film. For this reason, while high transparency is obtained about the electrically conductive film, detachment | desorption of the graphite oxide particle from the electrically conductive film obtained can be suppressed notably.

なお、本発明において、酸化黒鉛粒子の「平均粒径」とは、光学顕微鏡または電子顕微鏡を使って5個の酸化黒鉛粒子を観察した場合に、酸化黒鉛粒子の平面方向の粒径の平均値を言うものとする。ここで、「粒径」とは、光学顕微鏡または電子顕微鏡を使って酸化黒鉛粒子を観察したときの酸化黒鉛粒子の最も長い対角線の長さを言うものとする。   In the present invention, the “average particle size” of the graphite oxide particles means the average value of the particle sizes in the plane direction of the graphite oxide particles when five graphite oxide particles are observed using an optical microscope or an electron microscope. Shall be said. Here, “particle diameter” refers to the length of the longest diagonal line of graphite oxide particles when the graphite oxide particles are observed using an optical microscope or an electron microscope.

また本発明において、酸化黒鉛粒子の「平均厚さ」とは、原子間力顕微鏡を使って5個の酸化黒鉛粒子について測定された厚さの平均値を言うものとする。   In the present invention, the “average thickness” of graphite oxide particles refers to the average value of thicknesses measured for five graphite oxide particles using an atomic force microscope.

さらに本発明において「導電膜」とは、1.0×1012(Ω/□)以下の面積抵抗率を有する膜を言う。 Further, in the present invention, the “conductive film” refers to a film having a sheet resistivity of 1.0 × 10 12 (Ω / □) or less.

本発明によれば、酸化黒鉛粒子を還元する際の加熱処理温度が低くても、導電体の製造に要する時間を大幅に短縮できる導電体の製造方法が提供される。   ADVANTAGE OF THE INVENTION According to this invention, even if the heat processing temperature at the time of reduce | restoring a graphite oxide particle is low, the manufacturing method of the conductor which can reduce significantly the time which manufactures a conductor is provided.

以下、本発明の実施形態について詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail.

まず導電体の製造方法の実施形態について説明する。   First, an embodiment of a method for manufacturing a conductor will be described.

(導電体)
はじめに導電体の製造方法の実施形態の説明に先立ち、その製造方法により製造される導電体の構成について図1を用いて説明する。
(conductor)
First, prior to description of an embodiment of a method for manufacturing a conductor, a configuration of a conductor manufactured by the manufacturing method will be described with reference to FIG.

図1は、本実施形態の導電体の製造方法により製造される導電体の一例を示す側面図である。図1に示すように、本実施形態の導電体100は、基体1と、基体1の一面1a上に設けられる導電膜2とを備えている。   FIG. 1 is a side view showing an example of a conductor manufactured by the method for manufacturing a conductor according to the present embodiment. As shown in FIG. 1, the conductor 100 of this embodiment includes a base 1 and a conductive film 2 provided on one surface 1 a of the base 1.

基体1としては、ガラス板、ポリエチレンテレフタレートフィルム、ポリカーボネートフィルムなどが挙げられる。   Examples of the substrate 1 include a glass plate, a polyethylene terephthalate film, and a polycarbonate film.

導電膜2は導電性を有しており、酸化黒鉛粒子を含有する酸化黒鉛粒子含有液を基体1の一面1a上に塗布してフィルム状に形成し、乾燥してコート膜を得て、そのコート膜を加熱処理によって還元し、還元に際してコート膜を加湿することによって得られるものである。   The conductive film 2 has conductivity, and a graphite oxide particle-containing liquid containing graphite oxide particles is applied on the one surface 1a of the substrate 1 to form a film and dried to obtain a coat film. It is obtained by reducing the coat film by heat treatment and humidifying the coat film during the reduction.

(導電体の製造方法)
次に、導電体100の製造方法について説明する。
(Manufacturing method of conductor)
Next, a method for manufacturing the conductor 100 will be described.

まず酸化黒鉛粒子を含有する酸化黒鉛粒子含有液を準備する。酸化黒鉛粒子含有液は上述したように酸化黒鉛粒子を含む。   First, a graphite oxide particle-containing liquid containing graphite oxide particles is prepared. As described above, the graphite oxide particle-containing liquid contains graphite oxide particles.

酸化黒鉛粒子は、黒鉛を酸化することにより得られるものである。   Graphite oxide particles are obtained by oxidizing graphite.

酸化黒鉛粒子の形状は、特に限定されるものではなく、種々の形状であってもよい。例えば酸化黒鉛粒子の形状は球状であっても平板状であってもよい。ここで、酸化黒鉛粒子の形状が平板状であると好ましい。酸化黒鉛粒子の形状が平板状であると、形状異方性が高まり、形状異方性が小さい酸化黒鉛粒子と比べて、導電膜2に導電性を発現させるために必要な導電膜2中の酸化黒鉛粒子の含有率を少なくすることができ、結果的に得られる導電膜2からの酸化黒鉛粒子の脱離を抑制でき且つ導電膜2の透明性をより高めることができる。   The shape of the graphite oxide particles is not particularly limited, and may be various shapes. For example, the graphite oxide particles may be spherical or flat. Here, it is preferable that the graphite oxide particles have a flat plate shape. When the shape of the graphite oxide particles is a flat plate shape, the shape anisotropy is increased, and the conductive film 2 in the conductive film 2 necessary for expressing the conductivity as compared with the graphite oxide particles having a small shape anisotropy. The content rate of the graphite oxide particles can be reduced, the resulting detachment of the graphite oxide particles from the conductive film 2 can be suppressed, and the transparency of the conductive film 2 can be further increased.

酸化黒鉛粒子の形状が平板状である場合、酸化黒鉛粒子の平均粒径が100nm以上であり、且つ平均厚さが0.4nm〜10nmであることが好ましい。この場合、酸化黒鉛における基本層の層数が非常に少なく、平均厚さが薄いことで還元が容易となり、また、形状異方性が顕著に高く、そのため導電膜2に導電性を発現させるために必要な導電膜2中の酸化黒鉛粒子の含有率を低減することが可能となる。このため、導電膜2について高い透明性が得られるとともに、導電膜2からの酸化黒鉛粒子の脱離を顕著に抑制できる。このような酸化黒鉛粒子は、特開2002−53313号公報および特開2003−176116号公報で開示された方法を利用することにより製造できる。   When the shape of the graphite oxide particles is flat, the average particle size of the graphite oxide particles is preferably 100 nm or more and the average thickness is preferably 0.4 nm to 10 nm. In this case, the number of basic layers in the graphite oxide is very small, the average thickness is thin, the reduction is easy, and the shape anisotropy is remarkably high, so that the conductive film 2 is made conductive. It becomes possible to reduce the content rate of the graphite oxide particles in the conductive film 2 necessary for this. For this reason, high transparency is obtained for the conductive film 2 and the detachment of the graphite oxide particles from the conductive film 2 can be remarkably suppressed. Such graphite oxide particles can be produced by using the methods disclosed in JP-A-2002-53313 and JP-A-2003-176116.

上記酸化黒鉛粒子の原料として用いられる黒鉛には、各種黒鉛が使用可能であるが、層構造が発達した結晶性の高い黒鉛が酸化黒鉛製造の収率が高く、基本層の層数が少ない酸化黒鉛が得られやすいという理由から好ましい。このような黒鉛として、天然黒鉛(特に良質なもの)、キッシュ黒鉛(特に高温で作られたもの)、高配向性熱分解黒鉛が好ましく用いられる他、これらの黒鉛の層間を予め広げた膨張黒鉛も好ましく用いられる。また、黒鉛中の金属元素などの不純物は、予め約0.5質量%以下になるまで除去されていることが望ましい。   Various types of graphite can be used for the graphite used as a raw material for the above graphite oxide particles. However, highly crystalline graphite with a developed layer structure has a high yield in the production of graphite oxide and has a small number of basic layers. It is preferable because graphite is easily obtained. As such graphite, natural graphite (particularly good quality), quiche graphite (particularly made at high temperature), highly oriented pyrolytic graphite are preferably used, and expanded graphite in which the layers of these graphites are expanded in advance. Are also preferably used. Further, it is desirable that impurities such as metal elements in the graphite have been removed in advance until it becomes about 0.5% by mass or less.

黒鉛の平均粒径は、酸化黒鉛粒子の平均粒径に反映されるため、合成したい酸化黒鉛粒子の平均粒径に応じて適宜選択すればよい。具体的には、酸化黒鉛粒子の平均粒径が例えば100nm以上である場合には、黒鉛の平均粒径を0.1μm以上100μm以下とすればよい。ここで、黒鉛の平均粒径を0.5μm以上50μm以下とすることが好ましく、1μm以上25μm以下とすることがさらに好ましい。黒鉛の平均粒径が0.1μm以上であると、平均粒径が0.1μm未満の場合に比べて、得られる酸化黒鉛粒子のアスペクト比が大きくなって形状異方性が大きくなり、黒鉛の平均粒径が100μm以下であると、黒鉛の平均粒径が100μmを超える場合に比べて、酸化に要する時間を短縮することができる。   Since the average particle size of graphite is reflected in the average particle size of graphite oxide particles, it may be appropriately selected according to the average particle size of graphite oxide particles to be synthesized. Specifically, when the average particle diameter of the graphite oxide particles is, for example, 100 nm or more, the average particle diameter of the graphite may be 0.1 μm or more and 100 μm or less. Here, the average particle size of graphite is preferably 0.5 μm or more and 50 μm or less, and more preferably 1 μm or more and 25 μm or less. When the average particle size of the graphite is 0.1 μm or more, the aspect ratio of the obtained graphite oxide particles is increased and the shape anisotropy is increased as compared with the case where the average particle size is less than 0.1 μm. When the average particle size is 100 μm or less, the time required for oxidation can be shortened compared to the case where the average particle size of graphite exceeds 100 μm.

上記酸化黒鉛粒子としては、公知のBrodie法、Staudenmaier法、Hummers−Offeman法、特開2002−53313号公報および特開2003−176116号公報で開示される方法などによって、黒鉛を酸化することにより得られる酸化黒鉛粒子が利用できる。ここで、Brodie法は硝酸、塩素酸カリウムを使用して黒鉛を酸化させる方法であり、Staudenmaier法は、硝酸、硫酸及び塩素酸カリウムを使用して黒鉛を酸化させる方法である。またHummers−Offeman法は、硫酸、硝酸ナトリウム、過マンガン酸カリウムを使用して黒鉛を酸化する方法である。中でもHummers−Offeman法により製造することが、安全性が高く、短時間で酸化黒鉛粒子を製造できる点から好ましい。   The graphite oxide particles can be obtained by oxidizing graphite by a known Brodie method, Staudenmaier method, Hummers-Offeman method, methods disclosed in JP-A Nos. 2002-53313 and 2003-176116, and the like. Graphite oxide particles can be used. Here, the Brodie method is a method of oxidizing graphite using nitric acid and potassium chlorate, and the Staudenmeier method is a method of oxidizing graphite using nitric acid, sulfuric acid and potassium chlorate. The Hummers-Offeman method is a method of oxidizing graphite using sulfuric acid, sodium nitrate, and potassium permanganate. Among them, it is preferable to produce by the Hummers-Offeman method from the viewpoint that the safety is high and the graphite oxide particles can be produced in a short time.

ここで、Hummers−Offeman法は、
(1)硝酸ナトリウム、硫酸、過マンガン酸カリウム、黒鉛を混合することで黒鉛の層間に硫酸イオンを侵入させて、反応液中に硫酸−黒鉛層間化合物を生成させる層間化合物生成工程、
(2)上記反応液中に水を添加することで硫酸−黒鉛層間化合物に加水分解を起こし、酸化黒鉛を生成させる加水分解工程、及び
(3)反応液中に残存する硫酸イオン、マンガンイオン等の不純物イオンを除去して精製する精製工程を経て、酸化黒鉛からなる酸化黒鉛粒子を得るものである。
Here, the Hummers-Offeman method is
(1) An intercalation compound generating step of mixing sulfuric acid, potassium permanganate, and graphite to allow sulfate ions to enter between the graphite layers to form a sulfuric acid-graphite intercalation compound in the reaction solution;
(2) Hydrolysis step in which sulfuric acid-graphite intercalation compound is hydrolyzed by adding water to the reaction solution to produce graphite oxide, and (3) sulfate ion, manganese ion, etc. remaining in the reaction solution The graphite oxide particles made of graphite oxide are obtained through a purification step of removing and purifying the impurity ions.

上記層間化合物生成工程において、硝酸ナトリウム、硫酸、過マンガン酸カリウムの比率を、例えば質量比で硝酸ナトリウム10に対して、硫酸が828、過マンガン酸カリウムが60とすると、硫酸−黒鉛層間化合物を効果的に生成することができる。   In the intercalation compound generation step, when the ratio of sodium nitrate, sulfuric acid, and potassium permanganate is, for example, sodium nitrate 10 by mass ratio, sulfuric acid 828 and potassium permanganate 60, the sulfuric acid-graphite intercalation compound Can be generated effectively.

上記精製工程において反応液中に残存する不純物イオンを除去する方法としては、溶媒の添加操作と溶媒の除去操作とを繰り返す方法が例示できる。溶媒の除去操作には、デカンテーション、濾過、遠心分離、透析、イオン交換などの公知の手段を用いることができる。デカンテーションや濾過は、沈降が遅いために精製時間が長くなることや酸化黒鉛粒子による閉塞によってほとんど濾過ができないことから、比較的短時間で精製可能な遠心分離がより好ましい。   Examples of the method for removing impurity ions remaining in the reaction solution in the purification step include a method of repeating a solvent addition operation and a solvent removal operation. For the solvent removal operation, known means such as decantation, filtration, centrifugation, dialysis, and ion exchange can be used. In decantation and filtration, since sedimentation is slow, the purification time becomes long, and filtration is hardly possible due to clogging with graphite oxide particles. Therefore, centrifugation capable of purification in a relatively short time is more preferable.

上記のような操作を繰り返すことで層の分離が進むため、上記操作は、酸化黒鉛粒子の平均厚さが10nm以下になるまで繰り返すことが好ましく、5nm以下とすることがより好ましく、2nm以下とすることがさらに好ましい。該酸化黒鉛粒子の平均厚さが10nmを超えると、得られる酸化黒鉛粒子のアスペクト比が小さくなってしまう。   Since the separation of the layers proceeds by repeating the above operation, the above operation is preferably repeated until the average thickness of the graphite oxide particles is 10 nm or less, more preferably 5 nm or less, and 2 nm or less. More preferably. When the average thickness of the graphite oxide particles exceeds 10 nm, the aspect ratio of the obtained graphite oxide particles becomes small.

なお、上記精製工程においては、酸化黒鉛粒子同士の凝集を防止する観点から、上記溶媒として、比誘電率が15以上である液体を用いることが好ましく、中でも水を用いることが特に好ましい。ここで、水の中でも特にイオン交換水を用いることが好ましい。   In the purification step, from the viewpoint of preventing aggregation of graphite oxide particles, a liquid having a relative dielectric constant of 15 or more is preferably used as the solvent, and water is particularly preferably used. Here, it is particularly preferable to use ion-exchanged water among water.

上記精製工程終了後、酸化黒鉛粒子は、上述した酸化黒鉛粒子含有液を得るために通常、分散媒と混合される。この分散媒は必要に応じて適切なものを選択することが可能であるが、精製工程で用いる溶媒として水が用いられる場合には、分散媒としても水を用いることが、交換が不要でコストを低減できることから好ましい。   After the purification step, the graphite oxide particles are usually mixed with a dispersion medium in order to obtain the above-described graphite oxide particle-containing liquid. Although it is possible to select an appropriate dispersion medium as needed, when water is used as a solvent used in the purification process, it is not necessary to use water as the dispersion medium and the cost is not required. Can be reduced.

但し、精製工程で用いる溶媒として水が用いられる場合でも、分散媒として、必ずしも水を用いる必要はなく、例えば、メタノール、エタノール、アセトン、2−ブタノンなど、比誘電率が15以上の高極性液体を用いてもよい。このような水以外の高極性の液体を主な分散媒とするための手段として、元の分散液に含まれる水よりも十分多量の水以外の高極性液体を加えて希釈する方法、水以外の高極性液体を加えてから遠心分離とデカンテーションなどで上澄みを除くことを繰り返して水以外の高極性の分散媒に徐々に交換する方法、などが例示できる。また、数種類の液体を適当な割合で混合した液体を分散媒として用いることも可能である。この場合、一部に比誘電率15未満の液体を用いてもよい。   However, even when water is used as the solvent used in the purification process, it is not always necessary to use water as the dispersion medium. For example, methanol, ethanol, acetone, 2-butanone, or the like, a highly polar liquid having a relative dielectric constant of 15 or more. May be used. As a means for using such a highly polar liquid other than water as the main dispersion medium, a method of diluting by adding a sufficiently large amount of highly polar liquid other than water than the water contained in the original dispersion, other than water And a method of gradually exchanging the dispersion with a highly polar dispersion medium other than water by repeating the removal of the supernatant by centrifugation and decantation after adding the highly polar liquid. It is also possible to use a liquid obtained by mixing several kinds of liquids at an appropriate ratio as a dispersion medium. In this case, a liquid having a relative dielectric constant of less than 15 may be used in part.

上記酸化黒鉛粒子は、酸化黒鉛粒子含有液を得るために、分散媒のほか、さらに還元剤と混合される。このような還元剤としては、各種還元剤が利用可能である。なかでも、酸化黒鉛粒子含有液を乾燥して分散媒を除去する前には酸化黒鉛粒子中の酸素量を10質量%以上減少させず、少なくとも後述する還元工程において酸化黒鉛粒子を還元する作用を有する還元剤がより好ましい。   In order to obtain the graphite oxide particle-containing liquid, the graphite oxide particles are further mixed with a reducing agent in addition to the dispersion medium. Various reducing agents can be used as such a reducing agent. In particular, before removing the dispersion medium by drying the graphite oxide particle-containing liquid, the oxygen amount in the graphite oxide particles is not reduced by 10% by mass or more, and at least acts to reduce the graphite oxide particles in the reduction step described later. A reducing agent is more preferable.

ここで、この還元剤が、酸化黒鉛粒子含有液を乾燥して分散媒を除去する前に酸化黒鉛粒子中の酸素量を10質量%以上減少させないかどうかについては次のようにして測定することができる。即ちまず酸化黒鉛粒子含有液と比率を同一にした酸化黒鉛粒子、還元剤及び分散媒のみからなる液を作製し、25℃で1時間放置した後に還元剤を除去し、このときの液中に含まれる酸化黒鉛粒子中の酸素量を測定する。そして、この測定された酸素量と、予め還元剤と接触させない状態で測定された酸化黒鉛粒子中の酸素量との差を算出する。こうして、上記還元剤が、酸化黒鉛粒子中の酸素量を10質量%以上減少させないかどうかを判断することができる。   Here, whether or not this reducing agent does not reduce the oxygen content in the graphite oxide particles by 10 mass% or more before drying the graphite oxide particle-containing liquid and removing the dispersion medium is measured as follows. Can do. That is, first, a liquid composed of only graphite oxide particles, a reducing agent, and a dispersion medium having the same ratio as the liquid containing graphite oxide particles was prepared. After leaving at 25 ° C. for 1 hour, the reducing agent was removed. The amount of oxygen in the graphite oxide particles contained is measured. And the difference of this measured amount of oxygen and the amount of oxygen in the graphite oxide particle measured beforehand in the state which is not made to contact with a reducing agent is calculated. Thus, it can be determined whether the reducing agent does not reduce the oxygen content in the graphite oxide particles by 10 mass% or more.

この場合、酸化黒鉛粒子が、少なくとも後述する還元工程において還元剤によって還元されるので、還元による酸化黒鉛粒子同士の分散状態の悪化を抑制することができ、ひいては、酸化黒鉛粒子の含有率が低くても、得られる導電体100がより高い導電性を有することとなる。さらにまた、上記構成の還元剤が酸化黒鉛粒子含有液中に含まれていると、還元剤を用いない場合に比べて酸化黒鉛粒子含有液を低温で加熱しただけで酸化黒鉛粒子を還元させることができる。   In this case, since the graphite oxide particles are reduced by a reducing agent at least in the reduction step described later, the deterioration of the dispersion state between the graphite oxide particles due to the reduction can be suppressed, and consequently the content of the graphite oxide particles is low. However, the obtained conductor 100 has higher conductivity. Furthermore, when the reducing agent having the above structure is contained in the graphite oxide particle-containing liquid, the graphite oxide particles can be reduced only by heating the graphite oxide particle-containing liquid at a low temperature compared to the case where the reducing agent is not used. Can do.

上記のような還元剤としては、例えば、ヒドロキノン、レゾルシノール、カテコール、ピロガロール、没食子酸、L−システイン、ヨウ化水素酸、ヒドラジン、ホスフィン酸、クエン酸、チオ硫酸ナトリウム、チオ硫酸アンモニウム、次亜リン酸ナトリウム、ポリアクリル酸、L(+)アスコルビン酸などが挙げられ、中でもヒドロキノン、ピロガロール、ホスフィン酸が、より高い導電性が得られると言う理由から好ましく用いられる。   Examples of the reducing agent include hydroquinone, resorcinol, catechol, pyrogallol, gallic acid, L-cysteine, hydroiodic acid, hydrazine, phosphinic acid, citric acid, sodium thiosulfate, ammonium thiosulfate, and hypophosphorous acid. Sodium, polyacrylic acid, L (+) ascorbic acid and the like can be mentioned, among which hydroquinone, pyrogallol, and phosphinic acid are preferably used because higher conductivity is obtained.

上記酸化黒鉛粒子は、酸化黒鉛粒子含有液を得るために、分散媒、及び還元剤のほか、さらに高分子材料と混合されてもよい。上記高分子材料としては、上記分散媒に分散あるいは溶解する材料を使用することが望ましい。また上記酸化黒鉛粒子含有液は、必要に応じてバインダをさらに含有してもよい。この場合、バインダとして、上記分散媒に分散あるいは溶解する材料を使用すると好ましい。高分子材料及びバインダを上記分散媒に分散あるいは溶解する材料とすれば、実質的にすべての材料を均一に分散あるいは溶解させた酸化黒鉛粒子含有液を容易に得ることが可能である。   In order to obtain the graphite oxide particle-containing liquid, the graphite oxide particles may be further mixed with a polymer material in addition to the dispersion medium and the reducing agent. As the polymer material, it is desirable to use a material that is dispersed or dissolved in the dispersion medium. Moreover, the said graphite oxide particle containing liquid may further contain a binder as needed. In this case, it is preferable to use a material that is dispersed or dissolved in the dispersion medium as the binder. If the polymer material and the binder are materials that are dispersed or dissolved in the dispersion medium, it is possible to easily obtain a graphite oxide particle-containing liquid in which substantially all materials are uniformly dispersed or dissolved.

上記高分子材料又はバインダとしては、シリカゾルや有機シランなどの無機系材料、ポリカーボネート樹脂、ポリスチレン樹脂、ポリ塩化ビニル樹脂、メタクリル樹脂、フッ素樹脂、ポリイミド樹脂、ポリアミド樹脂、ポリアミドイミド樹脂、ポリビニルアルコール樹脂などの有機系材料、これらの材料を適当な溶媒に分散させたエマルジョンが挙げられる。   Examples of the polymer material or binder include inorganic materials such as silica sol and organic silane, polycarbonate resin, polystyrene resin, polyvinyl chloride resin, methacrylic resin, fluororesin, polyimide resin, polyamide resin, polyamideimide resin, and polyvinyl alcohol resin. And organic emulsions in which these materials are dispersed in a suitable solvent.

次に、上記のようにして得られた酸化黒鉛粒子含有液を、基体1の一面1a上に塗布してフィルム状に形成し、その後酸化黒鉛粒子含有液を乾燥させ、コート膜を形成する(コート膜形成工程)。   Next, the graphite oxide particle-containing liquid obtained as described above is applied on one surface 1a of the substrate 1 to form a film, and then the graphite oxide particle-containing liquid is dried to form a coat film ( Coating film forming step).

酸化黒鉛粒子含有液の塗布の方法は、基体1の一面1a上への塗布が可能であれば特に限定されるものではなく、例えばスピンコータ法、バーコータ法、ロールコータ法などの方法を用いることができる。   The method for applying the graphite oxide particle-containing liquid is not particularly limited as long as it can be applied onto the one surface 1a of the substrate 1. For example, a spin coater method, a bar coater method, a roll coater method or the like may be used. it can.

また酸化黒鉛粒子含有液の乾燥も特に限定されるものではなく、一般的な方法で行うことが可能である。   The drying of the graphite oxide particle-containing liquid is not particularly limited, and can be performed by a general method.

酸化黒鉛粒子含有液を乾燥して分散媒を除去する工程における加熱温度は、好ましくは30℃〜100℃、より好ましくは40℃〜80℃である。ただし、数分程度の短い時間であれば、高沸点の溶媒を除去する等の目的のために、200℃といった高温で加熱してもよい。   The heating temperature in the step of drying the graphite oxide particle-containing liquid and removing the dispersion medium is preferably 30 ° C to 100 ° C, more preferably 40 ° C to 80 ° C. However, the heating may be performed at a high temperature such as 200 ° C. for the purpose of removing the high boiling point solvent for a short time of about several minutes.

次に、上記のようにして得られるコート膜中の酸化黒鉛粒子を加熱処理して還元する(還元工程)。このとき、コート膜を加湿する(加湿工程)。こうして導電膜2を基体1の一面1a上に得ることができ、導電体100の製造が完了する。   Next, the graphite oxide particles in the coating film obtained as described above are reduced by heat treatment (reduction step). At this time, the coat film is humidified (humidification process). Thus, the conductive film 2 can be obtained on the one surface 1a of the substrate 1, and the manufacture of the conductor 100 is completed.

上記導電体100の製造方法によれば、上記還元工程が、コート膜を加湿する加湿工程を含むことで、還元工程において酸化黒鉛粒子を加熱処理する場合の温度が低くても、コート膜を加湿しない場合に比べて、導電膜2について十分な導電性が得られるまでの時間を大幅に短縮するこができ、ひいては導電体100の製造に要する時間を大幅に短縮することができる。また、酸化黒鉛粒子含有液が上記還元剤を含むため、還元剤を含まない場合に比べてより低い温度で酸化黒鉛粒子を部分的又は完全に還元させることができる。   According to the method for manufacturing the conductor 100, the reduction step includes a humidification step of humidifying the coating film, so that the coating film is humidified even when the temperature of the graphite oxide particles is heat-treated in the reduction step. Compared to the case where the conductive film 2 is not used, the time required to obtain sufficient conductivity for the conductive film 2 can be greatly reduced, and the time required for manufacturing the conductor 100 can be greatly reduced. Moreover, since the graphite oxide particle-containing liquid contains the reducing agent, the graphite oxide particles can be partially or completely reduced at a lower temperature than when no reducing agent is contained.

上記の還元工程における酸化黒鉛粒子の加熱処理は例えば100℃以下の温度で行うことが好ましく、80℃以下の温度で行うことがより好ましい。この場合、温度が100℃以下であることで、導電膜2を構成する高分子材料又はバインダの選択の幅を大幅に拡大することができる。なお、酸化黒鉛粒子を還元するためには、加熱処理は、50℃以上の温度で行うことが好ましく、60℃以上の温度で行うことがより好ましい。   The heat treatment of the graphite oxide particles in the reduction step is preferably performed at a temperature of 100 ° C. or less, for example, and more preferably at a temperature of 80 ° C. or less. In this case, when the temperature is 100 ° C. or lower, the range of selection of the polymer material or the binder constituting the conductive film 2 can be greatly expanded. In order to reduce the graphite oxide particles, the heat treatment is preferably performed at a temperature of 50 ° C. or higher, and more preferably at a temperature of 60 ° C. or higher.

また上記加湿工程におけるコート膜の加湿は、5%以上の湿度で行うことが好ましく、30%以上の湿度で行うことがより好ましい。この場合、湿度が5%以上となるように加湿を行うと、湿度が5%未満になる場合に比べて、導電膜2について十分な導電性が得られるまでの時間をより短縮することができる。但し、加湿は80%以下の湿度で行うことが好ましい。これは、湿度が80%以上では時間の短縮効果が少ないこと、そして、湿度を80%以下に抑えることで高分子材料又はバインダの劣化を抑制できることによるものである。   In addition, the humidification of the coating film in the humidification step is preferably performed at a humidity of 5% or more, and more preferably at a humidity of 30% or more. In this case, if humidification is performed so that the humidity becomes 5% or more, the time until sufficient conductivity can be obtained for the conductive film 2 can be further reduced as compared with the case where the humidity is less than 5%. . However, humidification is preferably performed at a humidity of 80% or less. This is because when the humidity is 80% or more, the effect of shortening the time is small, and by suppressing the humidity to 80% or less, the deterioration of the polymer material or the binder can be suppressed.

上記加湿は、上記還元工程において、酸化黒鉛粒子の加熱処理と同時に開始し、加熱処理時間と同時に終了させてもよく、酸化黒鉛粒子の加熱処理を開始した後、所定時間経過後に行ってもよい。また上記加湿は、上記還元工程において、酸化黒鉛粒子の加熱処理を開始した後、所定時間経過後に行い、加熱処理の終了前に終了させてもよい。   In the reduction step, the humidification may be started at the same time as the heat treatment of the graphite oxide particles and may be terminated at the same time as the heat treatment time, or may be performed after a predetermined time has elapsed after the heat treatment of the graphite oxide particles is started. . The humidification may be performed after a predetermined time has elapsed after the heat treatment of the graphite oxide particles is started in the reduction step, and may be terminated before the heat treatment is finished.

本発明は、上記実施形態に限定されるものではない。上記実施形態では、導電体100は、基体1と、基体1の一面1a上に設けられる導電膜2とを備えているが、導電膜2が自立性を有するものであれば、導電体は、基体1を含んでいなくても良い。例えば、導電膜2がポリイミド樹脂を含む場合には、導電体は基体1を含んでいなくても良い。なお、この場合、導電体は、上述した酸化黒鉛粒子含有液を基体1上に塗布して乾燥し、必要に応じて加熱処理を行って基体1上に導電膜2を得た後、基体1から導電膜2を剥離することによって得ることができる。   The present invention is not limited to the above embodiment. In the above embodiment, the conductor 100 includes the base body 1 and the conductive film 2 provided on the one surface 1a of the base body 1. However, if the conductive film 2 is self-supporting, the conductor is The substrate 1 may not be included. For example, when the conductive film 2 includes a polyimide resin, the conductor may not include the substrate 1. In this case, the conductor is coated with the above-described graphite oxide particle-containing liquid on the substrate 1, dried, and subjected to heat treatment as necessary to obtain the conductive film 2 on the substrate 1, and then the substrate 1 It can obtain by peeling the electrically conductive film 2 from.

以下、実施例及び比較例を挙げて本発明をさらに詳しく説明するが、本発明は以下の実施例に何ら限定されるものではない。   EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to a following example at all.

(実施例1)
エスイーシー社製天然黒鉛SNO―2(純度99.97質量%以上)10gを、硝酸ナトリウム(純度99%)7.5g、硫酸(純度96%)621g、過マンガン酸カリウム(純度99%)45gからなる混合液中に入れ、約20℃で5日間、緩やかに撹拌しながら放置した。得られた高粘土の液を5質量%硫酸水溶液1000cmに撹拌しながら約1時間で加えて、さらに2時間撹拌した。得られた液に過酸化水素(30質量%水溶液)30gを加えて、2時間撹拌した。
Example 1
10 g of natural graphite SNO-2 (purity 99.97% by mass or more) manufactured by ESC, from 7.5 g of sodium nitrate (purity 99%), 621 g of sulfuric acid (purity 96%), and 45 g of potassium permanganate (purity 99%) And then left at about 20 ° C. for 5 days with gentle stirring. The obtained high clay liquid was added to 1000 cm 3 of 5 mass% sulfuric acid aqueous solution in about 1 hour while stirring, and further stirred for 2 hours. Hydrogen peroxide (30 mass% aqueous solution) 30g was added to the obtained liquid, and it stirred for 2 hours.

この液を、3質量%硫酸/0.5質量%過酸化水素水の混合水溶液を用いた遠心分離と水を用いた遠心分離とで精製して、平板状の酸化黒鉛粒子(以下、「薄膜状粒子」と呼ぶ)の水分散液を得た。液の一部を40℃で真空乾燥させ、乾燥前後の質量変化を測定した結果から、液中の薄膜状粒子の濃度は1.3質量%と算出された。また、40℃で真空乾燥させた薄膜状粒子の元素分析で、酸素は42質量%、水素は2質量%であった。液の一部を水で希釈してからガラス板の上で乾燥させ、光学顕微鏡観察により薄膜状粒子の平面方向の粒径(平面内で最も長い対角線の長さ)を調べたところ、観察した範囲での粒径は、1〜7μmが大多数であり、その平均粒径は2.3μmであった。なお、光学顕微鏡観察で認められる各粒子の色は一部の例外を除いてはほぼ同様の色であり、大多数の粒子の厚みは同程度と判断された。一部の色の異なる粒子は他の粒子よりも色が濃いことから少量存在する厚みの厚い粒子である。さらに、原子間力顕微鏡を使って薄膜状粒子の厚みを評価したところ、5個の粒子で確認された厚みは3nm、3nm、5nm、6nm、9nmであり、平均厚さは5.2nmであった。以下、この分散液を「分散液A」と呼ぶ。   This solution was purified by centrifugal separation using a mixed aqueous solution of 3% by mass sulfuric acid / 0.5% by mass hydrogen peroxide and by centrifugation using water to obtain flat graphite oxide particles (hereinafter referred to as “thin film”). An aqueous dispersion of “like particles” was obtained. From the result of vacuum drying a part of the liquid at 40 ° C. and measuring the mass change before and after drying, the concentration of the thin film-like particles in the liquid was calculated to be 1.3% by mass. Further, elemental analysis of the thin film-like particles vacuum-dried at 40 ° C. revealed that oxygen was 42 mass% and hydrogen was 2 mass%. A portion of the liquid was diluted with water, dried on a glass plate, and the particle size in the plane direction of the thin film-like particles (the length of the longest diagonal line in the plane) was examined by optical microscope observation. The particle size in the range was 1 to 7 μm, and the average particle size was 2.3 μm. The color of each particle observed by optical microscope observation was almost the same with some exceptions, and the majority of the particles were judged to have the same thickness. Some of the particles having different colors are thicker than the other particles. Furthermore, when the thickness of the thin film-like particles was evaluated using an atomic force microscope, the thicknesses confirmed for the five particles were 3 nm, 3 nm, 5 nm, 6 nm, and 9 nm, and the average thickness was 5.2 nm. It was. Hereinafter, this dispersion is referred to as “dispersion A”.

分散液Aと水系グラスカ(JSR社製、固形分量40質量%、水60質量%)およびピロガロール(還元剤)を含有した液を、PC(ポリカーボネート)フィルム基体の上に塗布・乾燥しコート膜を形成した。コート膜中の酸化黒鉛粒子の濃度は2.5質量%、ピロガロール(還元剤)の濃度は2.25質量%でコート膜の厚みは150nm程度であった。乾燥は80℃で5分程度行った。乾燥後のフィルムの面積抵抗率は1×1013(Ω/□)以上であった。以下、このようにして作製されたフィルムを「フィルムA」と呼ぶ。 A liquid containing dispersion A, water-based glassca (manufactured by JSR, solid content 40% by mass, water 60% by mass) and pyrogallol (reducing agent) is applied onto a PC (polycarbonate) film substrate and dried to form a coating film. Formed. The concentration of graphite oxide particles in the coating film was 2.5% by mass, the concentration of pyrogallol (reducing agent) was 2.25% by mass, and the thickness of the coating film was about 150 nm. Drying was performed at 80 ° C. for about 5 minutes. The area resistivity of the film after drying was 1 × 10 13 (Ω / □) or more. Hereinafter, the film thus produced is referred to as “film A”.

フィルムAを恒温恒湿器(ESPEC社製恒温恒湿器プラチナスルシファー)に入れ、99℃の温度で、加湿を行った。このとき、湿度は5%とした。そして、適当なタイミングでフィルムAを上記恒温恒湿器から取り出して面積抵抗率を測定し、面積抵抗率が10(Ω/□)オーダーで面積抵抗率が加熱処理時間とともに変化しなくなった定常値に到達したフィルムAを導電体として得た。このとき、フィルムAを加湿してから面積抵抗率が上記定常値に到達するまでの到達時間を算出した。結果を表1に示す。 Film A was placed in a constant temperature and humidity chamber (a constant temperature and humidity chamber Platinum Sulifer manufactured by ESPEC), and humidified at a temperature of 99 ° C. At this time, the humidity was 5%. Then, the film A was taken out from the thermo-hygrostat at an appropriate timing, and the sheet resistivity was measured, and the sheet resistivity did not change with the heat treatment time when the sheet resistivity was on the order of 10 8 (Ω / □). The film A which reached the value was obtained as a conductor. At this time, the arrival time from when the film A was humidified until the area resistivity reached the steady value was calculated. The results are shown in Table 1.

(実施例2)
恒温恒湿器にてフィルムAを、湿度が30%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 2)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 30% with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例3)
恒温恒湿器にてフィルムAを、湿度が40%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 3)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 40% with a thermo-hygrostat. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例4)
恒温恒湿器にてフィルムAを、湿度が50%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
Example 4
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 50% with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例5)
恒温恒湿器にてフィルムAを、湿度が60%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 5)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 60% with a thermo-hygrostat. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例6)
恒温恒湿器にてフィルムAを、湿度が80%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 6)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 80% with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例7)
恒温恒湿器にてフィルムAを、湿度が98%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 7)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 98% with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例8)
恒温恒湿器にて、フィルムAを、80℃の温度下で湿度が60%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 8)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 60% at a temperature of 80 ° C. with a thermo-hygrostat. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例9)
恒温恒湿器にてフィルムAを、80℃の温度下で湿度が80%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
Example 9
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 80% at a temperature of 80 ° C. with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(実施例10)
恒温恒湿器にてフィルムAを、80℃の温度下で湿度が98%となるように加湿したこと以外は実施例1と同様にして導電体を得た。そして、実施例1と同様にして、フィルムAを加湿してから面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Example 10)
A conductor was obtained in the same manner as in Example 1 except that the film A was humidified so as to have a humidity of 98% at a temperature of 80 ° C. with a constant temperature and humidity chamber. Then, in the same manner as in Example 1, the arrival time from when the film A was humidified until the area resistivity reached a steady value was calculated. The results are shown in Table 1.

(比較例1)
恒温恒湿器にてフィルムAを加湿しなかったこと以外は実施例1と同様にして導電体を得た。そして、フィルムAの面積抵抗率が一定の値に到達するまでの到達時間を算出した。結果を表1に示す。
(Comparative Example 1)
A conductor was obtained in the same manner as in Example 1 except that the film A was not humidified with a constant temperature and humidity chamber. And the arrival time until the sheet resistivity of the film A reaches a certain value was calculated. The results are shown in Table 1.

(比較例2)
恒温恒湿器にて、80℃の温度下でフィルムAを加湿しなかったこと以外は実施例1と同様にして導電体を得た。そして、フィルムAの面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。
(Comparative Example 2)
A conductor was obtained in the same manner as in Example 1 except that the film A was not humidified at a temperature of 80 ° C. with a constant temperature and humidity chamber. And the arrival time until the area resistivity of the film A reaches a steady value was calculated. The results are shown in Table 1.

(参考例1)
フィルムAを乾燥機に入れ、加湿処理を行わずに140℃の温度で加熱処理を行ったこと以外は実施例1と同様にして導電体を得た。そして、フィルムAの面積抵抗率が定常値に到達するまでの到達時間を算出した。結果を表1に示す。

Figure 2010123280
(Reference Example 1)
A conductor was obtained in the same manner as in Example 1 except that the film A was put into a dryer and heat treatment was performed at a temperature of 140 ° C. without performing a humidification treatment. And the arrival time until the area resistivity of the film A reaches a steady value was calculated. The results are shown in Table 1.
Figure 2010123280

表1の結果より、実施例1〜7は、比較例1に比べて大幅に到達時間が短縮されることが分かった。また実施例8〜10は、比較例2に比べて大幅に到達時間が短縮されることが分かった。このことから、酸化黒鉛粒子を加熱処理するときに加湿を行うことで、同一処理温度での大幅な処理時間の短縮が図られることが分かった。なお、参考例1は、酸化黒鉛粒子の還元に際して、加湿をしなくても温度が高ければ短時間で十分な導電性が得られる例を示すものである。   From the results shown in Table 1, it was found that the arrival times of Examples 1 to 7 were significantly shortened as compared with Comparative Example 1. In addition, it was found that the arrival times of Examples 8 to 10 were significantly reduced as compared with Comparative Example 2. From this, it was found that by performing humidification when heat-treating the graphite oxide particles, the processing time at the same processing temperature can be greatly shortened. Reference Example 1 shows an example in which sufficient conductivity can be obtained in a short time if the temperature is high without humidification when reducing graphite oxide particles.

よって、本発明によれば、酸化黒鉛粒子を還元する際の加熱処理温度が低くても、導電体の製造に要する時間を大幅に短縮できることが確認された。   Therefore, according to the present invention, it was confirmed that the time required for the production of the conductor can be greatly shortened even if the heat treatment temperature when reducing the graphite oxide particles is low.

本発明に係る導電体の製造方法により製造される導電体の一例を示す側面図である。It is a side view which shows an example of the conductor manufactured by the manufacturing method of the conductor which concerns on this invention.

符号の説明Explanation of symbols

1…基体、2…導電膜、100…導電体。   DESCRIPTION OF SYMBOLS 1 ... Base | substrate, 2 ... Conductive film, 100 ... Conductor.

Claims (3)

導電膜を備えた導電体の製造方法において、
酸化黒鉛粒子及び還元剤を含有する酸化黒鉛粒子含有液をフィルム状に形成した後乾燥することによってコート膜を形成するコート膜形成工程と、
前記コート膜中の前記酸化黒鉛粒子を加熱処理して還元することで前記導電膜を備えた導電体を形成する還元工程とを含み、
前記還元工程が、前記コート膜を加湿する加湿工程を含む、導電体の製造方法。
In a method for producing a conductor provided with a conductive film,
A coating film forming step of forming a coating film by forming a graphite oxide particle-containing liquid containing graphite oxide particles and a reducing agent into a film and then drying;
Including a reduction step of forming a conductor including the conductive film by reducing the graphite oxide particles in the coat film by heat treatment,
The conductor manufacturing method, wherein the reducing step includes a humidifying step of humidifying the coat film.
前記還元剤が、前記酸化黒鉛粒子含有液の乾燥前には、前記酸化黒鉛粒子中の酸素量を10質量%以上減少させず、少なくとも前記還元工程において前記酸化黒鉛粒子を還元する作用を有する、請求項1に記載の導電体の製造方法。   The reducing agent does not decrease the oxygen amount in the graphite oxide particles by 10 mass% or more before drying the graphite oxide particle-containing liquid, and has an action of reducing the graphite oxide particles at least in the reduction step. The manufacturing method of the conductor of Claim 1. 前記酸化黒鉛粒子が平板状であり、100nm以上の平均粒径及び0.4nm〜10nmの平均厚さを有する、請求項1又は2に記載の導電体の製造方法。   The method for producing a conductor according to claim 1 or 2, wherein the graphite oxide particles are flat and have an average particle diameter of 100 nm or more and an average thickness of 0.4 nm to 10 nm.
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