JP2005325012A - Method for processing carbonaceous material, carbonaceous material with improved graphitic property, electron emitting material using it, and battery electrode material - Google Patents

Method for processing carbonaceous material, carbonaceous material with improved graphitic property, electron emitting material using it, and battery electrode material Download PDF

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JP2005325012A
JP2005325012A JP2005105669A JP2005105669A JP2005325012A JP 2005325012 A JP2005325012 A JP 2005325012A JP 2005105669 A JP2005105669 A JP 2005105669A JP 2005105669 A JP2005105669 A JP 2005105669A JP 2005325012 A JP2005325012 A JP 2005325012A
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carbonaceous material
boron
carbon nanotubes
carbonaceous
carbon nanotube
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Masahiro Inohara
雅博 井ノ原
Yuji Ozeki
雄治 尾関
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Toray Industries Inc
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbonaceous material treated with boron, an electron emitting material using it, a battery electrode material, and a method for manufacturing them at a low cost. <P>SOLUTION: A carbonaceous material is treated with a material containing boron at 60-500°C. By this treatment, a carbonaceous material with an improved graphitic property is obtained. Especially, the carbonaceous material contains carbon nanotubes which consist of 1-5 layers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、炭素質材料の処理方法に関するものであり、特にカーボンナノチューブを含有する炭素質材料をホウ素処理することで得られる、炭素質材料、およびそれを用いた電子放出材料、電池電極材料、ならびにこれらの製造方法に関する。   The present invention relates to a method for treating a carbonaceous material, and in particular, a carbonaceous material obtained by boron treatment of a carbonaceous material containing carbon nanotubes, and an electron emission material, a battery electrode material using the carbonaceous material, The present invention also relates to a manufacturing method thereof.

カーボンナノチューブは、グラファイトの１枚面を巻いて筒状にした形状を有しており、１層に巻いたものを単層カーボンナノチューブ、２層に巻いたものを２層カーボンナノチューブ、多層に巻いたものを多層カーボンナノチューブという。   A carbon nanotube has a shape in which one surface of graphite is wound into a cylindrical shape. A single-walled carbon nanotube is wound in one layer, a double-walled carbon nanotube is wound in two layers, and is wound in multiple layers. This was called multi-walled carbon nanotube.

カーボンナノチューブは、高い機械的強度、高い導電性を有することから、燃料電池やリチウム２次電池用負極材、樹脂や有機半導体との複合材料からなる高強度樹脂、導電性樹脂、電磁波シールド材として期待されており、さらに、Ｌ／Ｄ（長さ／直径の比）が大きく、直径は数ｎｍであることから、走査型トンネル顕微鏡用プローブ、電界電子放出源、ナノピンセットとして期待されており、また、ナノサイズの空間を有することから、吸着材料、医療用ナノカプセル、ＭＲＩ造影剤として期待されている。 いずれの用途の場合にも、高純度のカーボンナノチューブが要求されており、カーボンナノチューブとしては直径の細い単層や２層のカーボンナノチューブが有利であり、グラファイト層の欠陥が少ない方が特性的に優れている。   Since carbon nanotubes have high mechanical strength and high conductivity, they are used as anode materials for fuel cells and lithium secondary batteries, high-strength resins made of composite materials with resins and organic semiconductors, conductive resins, and electromagnetic shielding materials. Furthermore, since L / D (ratio of length / diameter) is large and the diameter is several nm, it is expected as a probe for scanning tunneling microscope, field electron emission source, nanotweezers, Moreover, since it has a nano-sized space, it is expected as an adsorbing material, a medical nanocapsule, and an MRI contrast agent. In any application, high-purity carbon nanotubes are required, and as carbon nanotubes, single-walled or double-walled carbon nanotubes with a small diameter are advantageous. Are better.

炭素質材料の導電性や熱伝導性を改善するための処理方法として、いくつかの方法が提案されているが、なかでも、高温で処理する方法（特許文献１）や、高温でホウ素を導入する方法（特許文献２）が提案されている。しかしいずれも１０００℃以上の高温での処理が必要であり、製造コストが高くなるという問題があった。
特開２００３−１１５３０２号公報 特許３４６１８０５号公報 Several methods have been proposed as treatment methods for improving the conductivity and thermal conductivity of carbonaceous materials. Among them, a method of treating at a high temperature (Patent Document 1) and introducing boron at a high temperature are proposed. A method (Patent Document 2) is proposed. However, both of them require treatment at a high temperature of 1000 ° C. or higher, and there is a problem that the manufacturing cost increases.
JP 2003-115302 A Japanese Patent No. 3461805

本発明は、上記のような事情に鑑みなされたものであり、ホウ素処理した炭素質材料およびそれを用いた電子放出材料、電池電極材料、ならびにこれらの製造方法の提供を目的とする。   The present invention has been made in view of the above circumstances, and an object thereof is to provide a boron-treated carbonaceous material, an electron-emitting material using the same, a battery electrode material, and a method for producing the same.

前記課題を達成するため、本発明は主として次のような構成をとる。   In order to achieve the above object, the present invention mainly has the following configuration.

すなわち、炭素質材料をホウ素を含む材料とともに６０℃以上５００℃以下で処理することを特徴とする、炭素質材料の処理方法、特に、炭素質材料がカーボンナノチューブを含有することを特徴とし、カーボンナノチューブが１〜５層であることを特徴とする。   That is, a carbonaceous material is treated at 60 ° C. or more and 500 ° C. or less together with a material containing boron, and in particular, the carbonaceous material is characterized in that the carbonaceous material contains carbon nanotubes. The nanotube has 1 to 5 layers.

本発明によれば、ホウ素を含む炭素質材料およびその組成物を、低温で、安価に得ることができる。   According to the present invention, a carbonaceous material containing boron and a composition thereof can be obtained at a low temperature and at a low cost.

本発明の方法により、グラファイト性が向上した炭素質材料を得ることができる。   By the method of the present invention, a carbonaceous material having improved graphite properties can be obtained.

本発明により得られた炭素質材料を用いることにより、電子放出特性の良好な材料を得ることができる。   By using the carbonaceous material obtained by the present invention, a material having good electron emission characteristics can be obtained.

本発明により得られた炭素質材料は、塗料や樹脂への添加剤用途、電子部品用途、医療用途など、その用途は広く期待できる。さらに、本発明によりグラファイト性が向上したことにより、各用途での電気的特性が向上し、性能向上が期待できる。   The carbonaceous material obtained by the present invention can be widely expected to be used for additives such as paints and resins, electronic parts, and medical applications. Furthermore, since the graphite property is improved by the present invention, electrical characteristics in each application are improved, and an improvement in performance can be expected.

以下、本発明の最良の実施形態の例を説明する。   Examples of the best embodiment of the present invention will be described below.

本発明は、処理空間内に炭素質材料とホウ素を含む材料を供給した状態で、６０℃以上、５００℃以下で炭素質材料を処理する方法を特徴とする。   The present invention is characterized by a method of treating a carbonaceous material at 60 ° C. or more and 500 ° C. or less in a state where a carbonaceous material and a material containing boron are supplied into the treatment space.

炭素質材料は、例えばカーボンナノチューブ、フラーレン、活性炭、カーボンブラック、グラファイト、アモルファスカーボン、炭素繊維などを挙げることができる。なかでも、カーボンナノチューブの処理に好ましく、１〜５層のカーボンナノチューブの処理に特に好ましい。   Examples of the carbonaceous material include carbon nanotubes, fullerenes, activated carbon, carbon black, graphite, amorphous carbon, and carbon fibers. Especially, it is preferable for the process of a carbon nanotube, and is especially preferable for the process of a 1-5 layer carbon nanotube.

本発明でのホウ素を含む材料との処理方法は、固体状態の炭素質材料と、ホウ素含有材料とを接触させることが特徴であるが、ホウ素含有材料の状態としては、気相および液相、固相状態のいずれでも良く、特に反応温度を低く抑えることができるので、液相状態にあることが好ましい。   The treatment method with a material containing boron in the present invention is characterized in that a solid-state carbonaceous material and a boron-containing material are brought into contact with each other. Examples of the state of the boron-containing material include a gas phase and a liquid phase, Any of a solid phase state may be sufficient, and since the reaction temperature can be suppressed especially low, it is preferable to be in a liquid phase state.

本発明における処理温度は、６０℃以上、５００℃以下であることが必須であるが、ホウ素が炭素質材料中に導入されれば、特に限定されるものではない。   The treatment temperature in the present invention is essential to be 60 ° C. or higher and 500 ° C. or lower, but is not particularly limited as long as boron is introduced into the carbonaceous material.

気相状態のホウ素を含む材料としては、どのような種類のものを用いても良いが、ホウ素、酸化ホウ素、窒化ホウ素、ホウフッ化アンモニウムなど、気相になりやすいものが好ましい。処理する際、減圧状態にすると、ホウ素化合物が気相状態になりやすく好ましい。   As a material containing boron in a gas phase state, any kind of material may be used, but materials that are likely to be in a gas phase such as boron, boron oxide, boron nitride, and ammonium borofluoride are preferable. In the treatment, it is preferable to use a reduced pressure state because the boron compound tends to be in a gas phase.

気相状態での処理方法の場合、炭素質材料を保護する目的で、酸素を含まない状況での処理が好ましい。酸素を含んだ状態で処理すると、炭素質材料が燃えてなくなってしまう可能性がある。   In the case of a treatment method in a gas phase, treatment in a situation not containing oxygen is preferable for the purpose of protecting the carbonaceous material. If treated in a state containing oxygen, the carbonaceous material may not burn.

液相状態のホウ素を含む材料としては、どのような種類のものを用いても良いが、ホウ酸、酸化ホウ素、ホウ素、窒化ホウ素、ホウフッ化アンモニウムなど、溶液状態となるものが好ましい。   As a material containing boron in a liquid phase state, any kind of material may be used, but materials in a solution state such as boric acid, boron oxide, boron, boron nitride, and ammonium borofluoride are preferable.

液相でホウ素を含む材料と処理する場合、ホウ素を含む材料を融解する温度まで上げて反応させてもかまわないが、ホウ素含有材料が溶解する溶剤を用いると、反応温度を下げることができるので好ましい。   When processing with a material containing boron in the liquid phase, the reaction may be performed by raising the temperature of the material containing boron to a temperature at which the material containing boron is melted. However, if a solvent in which the boron-containing material is dissolved is used, the reaction temperature can be lowered. preferable.

ホウ素含有材料を溶解する溶剤としては、ホウ素含有材料が溶解すればどのようなものでもかまわないが、操作性、安全性、価格などの点から、一般に市販されている有機溶剤、水などが好ましく、特に水が好ましい。   As the solvent for dissolving the boron-containing material, any solvent can be used as long as the boron-containing material dissolves. However, from the viewpoint of operability, safety, price, etc., a commercially available organic solvent, water, etc. are preferable. In particular, water is preferred.

液相状態のホウ素含有材料と炭素質材料を処理する場合、ホウ素を含む液相中に炭素質材料を浸すことで処理できるが、温度をかけた処理をする場合、還流操作などを併用することが好ましい。   When processing boron-containing materials and carbonaceous materials in the liquid phase, they can be treated by immersing the carbonaceous material in a liquid phase containing boron. However, when processing at an elevated temperature, use a reflux operation together. Is preferred.

炭素質材料とホウ素を含む液相を接触させる際、固液比として１／１０〜１／１００００の比率で接触させることが好ましく、特に好ましくは１／２０〜１／５０００の比率で接触させることが好ましい。   When the carbonaceous material and the liquid phase containing boron are brought into contact with each other, the solid-liquid ratio is preferably brought into contact at a ratio of 1/10 to 1/10000, particularly preferably at a ratio of 1/20 to 1/5000. Is preferred.

ホウ素を含む液相としては、溶融状態のものであれば濃度は１００％であるが、溶液状態とする場合、濃度が高いほど好ましい。しかし、各溶媒への溶解性は限度があるので、飽和溶液状態で反応させることが好ましい。具体的には、５ｗｔ％〜８０ｗｔ％の溶液を用いることが好ましく、特に好ましくは１０ｗｔ％〜７０ｗｔ％の溶液を用いることが好ましい。   As a liquid phase containing boron, the concentration is 100% if it is in a molten state, but when it is in a solution state, the higher the concentration, the better. However, since the solubility in each solvent is limited, the reaction is preferably carried out in a saturated solution state. Specifically, a 5 wt% to 80 wt% solution is preferably used, and a 10 wt% to 70 wt% solution is particularly preferably used.

液相でホウ素を含む材料と処理する場合、その処理条件は撹拌しながら行うことが好ましく、その反応温度は高い程良いが、操作性の点から、溶剤の沸点付近で還流させながら行うことが好ましい。   When processing with a boron-containing material in the liquid phase, the processing conditions are preferably performed while stirring, and the higher the reaction temperature, the better. However, from the viewpoint of operability, it is performed while refluxing near the boiling point of the solvent. preferable.

固相状態のホウ素を含む材料としては、どのような種類のものを用いても良く、具体的にはホウ酸、酸化ホウ素、ホウ素、窒化ホウ素、ホウフッ化アンモニウムなどが挙げられる。   As a material containing boron in a solid state, any kind of material may be used, and specific examples include boric acid, boron oxide, boron, boron nitride, and ammonium borofluoride.

固相でホウ素を含む材料と処理する場合、その処理条件は撹拌しながら行うことが好ましい。   When processing with a material containing boron in a solid phase, the processing conditions are preferably performed with stirring.

固相状態のホウ素含有材料と炭素質材料を処理する場合、ハイブリッドミキサー、ホモジナイザー、ミキサー、混練機などを用いて混ぜ込むことが好ましい。   When processing a boron-containing material and a carbonaceous material in a solid state, it is preferable to mix them using a hybrid mixer, a homogenizer, a mixer, a kneader or the like.

ホウ素を含む材料との処理によって、炭素質材料中にホウ素が含まれ、該炭素質材料のグラファイト性が改良できる。この理由は現時点で明らかではないが、以下のように推察される。炭素質材料のグラファイト層には欠陥があり、その欠陥がグラファイト性を阻害している。この欠陥部分にホウ素が入り込むことにより、炭素質材料のグラファイト性が修復され、向上すると考えられる。このホウ素が入り込むことによってグラファイト性が向上するのは、ホウ素の電子構造により、構造が安定化されるものと考えられる。そのため、同じ電子構造を持つ１３族（ＩＩＩＡ族）元素を用いても同じ効果を得ることができると考えられる。１３族（ＩＩＩＡ族）元素としては、ホウ素の他にアルミニウム、ガリウム、インジウム、タリウムが挙げられる。   By the treatment with the material containing boron, boron is contained in the carbonaceous material, and the graphite property of the carbonaceous material can be improved. The reason for this is not clear at this time, but is presumed as follows. There is a defect in the graphite layer of the carbonaceous material, and the defect inhibits the graphite property. It is considered that by entering boron into the defective portion, the graphitic property of the carbonaceous material is repaired and improved. It is considered that the graphitic property is improved by entering boron, because the structure is stabilized by the electronic structure of boron. Therefore, it is considered that the same effect can be obtained even when a group 13 (group IIIA) element having the same electronic structure is used. Examples of the group 13 (IIIA group) element include aluminum, gallium, indium, and thallium in addition to boron.

本発明は、特にカーボンナノチューブを含有する炭素質材料をホウ素を含む材料と処理することを特徴とする。カーボンナノチューブは、高い機械的強度、高い導電性を有することから、燃料電池やリチウム２次電池用負極材、樹脂や有機半導体との複合材料からなる高強度樹脂、導電性樹脂、電磁波シールド材として期待されており、さらに、Ｌ／Ｄ（長さ／直径の比）が大きく、直径は数ｎｍであることから、走査型トンネル顕微鏡用プローブ、電界電子放出源、ナノピンセットとして期待されており、また、ナノサイズの空間を有することから、吸着材料、医療用ナノカプセル、ＭＲＩ造影剤として期待されている。   The present invention is particularly characterized in that a carbonaceous material containing carbon nanotubes is treated with a material containing boron. Since carbon nanotubes have high mechanical strength and high conductivity, they are used as anode materials for fuel cells and lithium secondary batteries, high-strength resins made of composite materials with resins and organic semiconductors, conductive resins, and electromagnetic shielding materials. Furthermore, since L / D (ratio of length / diameter) is large and the diameter is several nm, it is expected as a probe for scanning tunneling microscope, field electron emission source, nanotweezers, Moreover, since it has a nano-sized space, it is expected as an adsorbing material, a medical nanocapsule, and an MRI contrast agent.

カーボンナノチューブの形態は、高分解能透過型電子顕微鏡で調べることができる。グラファイトの層は、透過型電子顕微鏡でまっすぐにはっきりと見えるほど好ましいが、グラファイト層は乱れていても構わない。グラファイト層が乱れたものは、カーボンナノファイバーと定義することがあるが、このようなカーボンナノファイバーも本発明においてはカーボンナノチューブに含むものとする。カーボンナノチューブは、一般にレーザーアブレーション法、アーク放電法、熱ＣＶＤ法、プラズマＣＶＤ法、燃焼法などで製造できるが、どのような方法で製造したカーボンナノチューブでも構わない。篠原らが報告しているようにゼオライトを触媒の担体としてアセチレンを原料に熱ＣＶＤ法で作る方法は、特に精製することなく、多少の熱分解炭素等の炭素被覆はあるものの、純度が高く、良くグラファイト化されたカーボンナノチューブが得られる点で特に好ましい方法である（Ｃｈｅｍｉｃａｌ Ｐｈｙｓｉｃｓ Ｌｅｔｔｅｒｓ ３０３（１９９９） １１７−１２４）。このようなカーボンナノチューブを使えば、ホウ素を含む材料と処理することにより、特にグラファイト性の高い炭素質材料を得ることができる。   The form of the carbon nanotube can be examined with a high-resolution transmission electron microscope. The graphite layer is preferred so that it can be seen straight and clearly in a transmission electron microscope, but the graphite layer may be disordered. What disturbs the graphite layer may be defined as carbon nanofiber, and such carbon nanofiber is also included in the carbon nanotube in the present invention. The carbon nanotubes can be generally produced by a laser ablation method, an arc discharge method, a thermal CVD method, a plasma CVD method, a combustion method, or the like, but the carbon nanotubes produced by any method may be used. As reported by Shinohara et al., The method of making acetylene as a raw material by a thermal CVD method using zeolite as a catalyst support has a high purity, although there is some carbon coating such as pyrolytic carbon without any particular purification. This is a particularly preferable method in that well graphitized carbon nanotubes can be obtained (Chemical Physics Letters 303 (1999) 117-124). If such a carbon nanotube is used, a carbonaceous material having a particularly high graphite property can be obtained by processing with a material containing boron.

カーボンナノチューブの層数は、高分解能透過型電子顕微鏡で調べることができる。日立製Ｈ−９０００ＵＨＲ ＩＩＩなどの高性能な顕微鏡であれば、１００万倍の倍率で拡大して観察したとき、グラファイト層の１枚１枚を観察することができ、カーボンナノチューブの層数を数えることができる。また、グラファイト層の間隔は０．３ｎｍ〜０．５ｎｍの間隔であるのに対し、カーボンナノチューブの内径は０．５ｎｍ以上あり、カーボンナノチューブの内径および外径、層数を測定することができる。   The number of carbon nanotube layers can be examined with a high-resolution transmission electron microscope. A high-performance microscope such as Hitachi's H-9000UHR III can observe each of the graphite layers one by one when magnified at a magnification of 1 million, and counts the number of carbon nanotube layers be able to. Further, while the interval between the graphite layers is 0.3 nm to 0.5 nm, the inner diameter of the carbon nanotube is 0.5 nm or more, and the inner and outer diameters and the number of layers of the carbon nanotube can be measured.

本発明におけるカーボンナノチューブ含有炭素質材料は共鳴ラマン分光法により評価が可能である。ラマンスペクトルにおいて１５９０ｃｍ−１付近に見られるラマンシフトはグラファイト由来のＧバンドと呼ばれ、１３５０ｃｍ−１付近に見られるラマンシフトはアモルファスカーボンやグラファイトの欠陥に由来のＤバンドと呼ばれる。このＧ／Ｄ比が高いほどグラファイト化度が高く、高品質なカーボンナノチューブを意味する。 The carbon nanotube-containing carbonaceous material in the present invention can be evaluated by resonance Raman spectroscopy. In the Raman spectrum, the Raman shift seen in the vicinity of 1590 cm −1 is called a G band derived from graphite, and the Raman shift seen in the vicinity of 1350 cm −1 is called a D band derived from defects in amorphous carbon or graphite. The higher the G / D ratio, the higher the degree of graphitization, which means a higher quality carbon nanotube.

本発明におけるホウ素を含有する材料と処理する前に、酸などの薬液処理により、炭素質材料の表面に欠陥部分を付与することが望ましい。欠陥部分を付与することにより、導入されるホウ素の量が増え、炭素質材料のグラファイト性がさらに向上することが期待されるので好ましい。   Prior to the treatment with the boron-containing material in the present invention, it is desirable to impart a defective portion to the surface of the carbonaceous material by treatment with a chemical solution such as an acid. By imparting a defect portion, the amount of boron to be introduced is increased, and it is expected that the graphite property of the carbonaceous material is further improved, which is preferable.

また、前処理する薬液としては、炭素質材料の表面に欠陥部分を作れれば特に限定されないが、硫酸、硝酸、塩酸などの酸が有効であり、単一で用いても混合して用いても良いが、グラファイト層の処理という点では、より強力に処理できる硫酸、硝酸またはこれらの混合物が好ましい。   The pretreatment chemical solution is not particularly limited as long as a defective portion can be formed on the surface of the carbonaceous material, but acids such as sulfuric acid, nitric acid, hydrochloric acid are effective, and even when used alone, they can be mixed and used. However, in terms of the treatment of the graphite layer, sulfuric acid, nitric acid, or a mixture thereof that can be treated more strongly is preferable.

本発明のホウ素を含む材料との処理は、特に、層数の少ないカーボンナノチューブに好ましく、１〜５層のカーボンナノチューブに好ましい。層数の少ないカーボンナノチューブは、層数の多いカーボンナノチューブに比べ、耐酸化性など耐久性が無く、例えば、高温で処理する方法によって、グラファイト性を改良する手段が知られているが、これらは酸化のコントロールが難しく、層数の少ないカーボンナノチューブをすべて燃やしてしまうなどの欠点がある。それに比較して本発明の方法は低温で処理できるので、層数の少ないナノチューブの構造を破壊することなく、グラファイト性、導電性を改良できる。   The treatment with the boron-containing material of the present invention is particularly preferable for carbon nanotubes having a small number of layers, and is preferable for carbon nanotubes having 1 to 5 layers. Carbon nanotubes with a small number of layers are not durable, such as oxidation resistance, compared to carbon nanotubes with a large number of layers. For example, means for improving graphite properties by a method of processing at a high temperature are known. Oxidation is difficult to control, and all the carbon nanotubes with a small number of layers are burned. In contrast, since the method of the present invention can be processed at a low temperature, the graphite property and conductivity can be improved without destroying the structure of the nanotube having a small number of layers.

本発明での手法により、ホウ素を含有し、多本数のカーボンナノチューブを含有する構成からなり、そのカーボンナノチューブ総本数の１０％以上が１〜５層のカーボンナノチューブである炭素質材料を得ることが可能となった。   By the method of the present invention, it is possible to obtain a carbonaceous material comprising boron and having a structure containing a large number of carbon nanotubes, wherein 10% or more of the total number of carbon nanotubes is 1 to 5 layers of carbon nanotubes. It has become possible.

ここで、カーボンナノチューブ総本数中の１０％以上が１〜５層のカーボンナノチューブであるとは、カーボンナノチューブ含有組成物を透過型電子顕微鏡で１００万倍で観察し、１５０ｎｍ四方の視野の中で視野面積の１０％がカーボンナノチューブで、かつ１０本以上のカーボンナノチューブが含まれ、そのうちの１０％以上の本数が１〜５層のカーボンナノチューブである写真を撮ることができるような組成物のことであり、上記測定を１０箇所について行った平均値で評価する。   Here, 10% or more of the total number of carbon nanotubes is 1 to 5 layers of carbon nanotubes. The carbon nanotube-containing composition is observed with a transmission electron microscope at a magnification of 1 million times, and within a 150 nm square field of view. A composition that can take a photograph in which 10% of the viewing area is carbon nanotubes and 10 or more carbon nanotubes are included, and 10% or more of them are 1 to 5 carbon nanotubes. It is evaluated by an average value obtained by measuring the above-mentioned measurement at 10 locations.

本発明のカーボンナノチューブ含有組成物において、１〜５層カーボンナノチューブの割合は多いほど好ましく、より好ましくは５０％以上であるようにするのがよい。   In the carbon nanotube-containing composition of the present invention, the proportion of 1 to 5 carbon nanotubes is preferably as large as possible, and more preferably 50% or more.

本発明のカーボンナノチューブ含有組成物において、伝導度を向上するために、グラファイト骨格中にホウ素が含まれることが好ましい。   In the carbon nanotube-containing composition of the present invention, it is preferable that boron is contained in the graphite skeleton in order to improve conductivity.

炭素質材料中にホウ素が含まれるかどうかは、一般に用いられる元素分析によって確認できる。本発明により得られる炭素質材料として、ホウ素元素は０．１％以上含有されることが好ましく、さらに好ましくは０．５％以上含有されることが好ましい。   Whether or not boron is contained in the carbonaceous material can be confirmed by a commonly used elemental analysis. As the carbonaceous material obtained by the present invention, boron element is preferably contained in an amount of 0.1% or more, more preferably 0.5% or more.

また、グラファイト骨格中にホウ素が含まれるようになったかどうかは、ＸＰＳ分析による組成分析により、ホウ素−炭素結合の存在を確認することで実施できる。   Whether or not boron is contained in the graphite skeleton can be confirmed by confirming the presence of a boron-carbon bond by composition analysis by XPS analysis.

炭素質材料中にホウ素が含まれることにより、該炭素質材料のグラファイト性が改良できる。この理由は現時点で明らかではないが、以下のように推察される。炭素質材料のグラファイト層には欠陥があり、その欠陥がグラファイト性を阻害している。この欠陥部分にホウ素が入り込むことにより、炭素質材料のグラファイト性が修復され、向上すると考えられる。   When boron is contained in the carbonaceous material, the graphite property of the carbonaceous material can be improved. The reason for this is not clear at this time, but is presumed as follows. There is a defect in the graphite layer of the carbonaceous material, and the defect inhibits the graphite property. It is considered that by entering boron into the defective portion, the graphitic property of the carbonaceous material is repaired and improved.

また、炭素質材料のグラファイト性が向上することにより炭素質材料の導電性が高くなることが考えられる。このように導電性が向上した炭素質材料を用いることにより、電子放出材料、電池電極材料としての特性が向上すると考えられる。   Moreover, it is conceivable that the conductivity of the carbonaceous material is increased by improving the graphite property of the carbonaceous material. Thus, it is thought that the characteristics as an electron emission material and a battery electrode material are improved by using a carbonaceous material having improved conductivity.

上記方法によってグラファイト性を向上した炭素質材料は、電子放出材料、電池電極材料への適用が好適な使用形態の例として挙げられるが、これに限定されるものではない。   Although the carbonaceous material which improved the graphite property by the said method is mentioned as an example of the usage form suitable for application to an electron emission material and a battery electrode material, it is not limited to this.

電子放出材料としてはフィールドエミッションディスプレー（ＦＥＤ）への適用が例示されるが、特に限定されるものではない。   The electron emission material is exemplified by application to a field emission display (FED), but is not particularly limited.

電池電極材料としては、リチウムイオン二次電池の陽極基材および陰極基材、燃料電池の電極基材、燃料電池用触媒担体などへの適用が好ましいが、特に限定されるものではない。   The battery electrode material is preferably applied to an anode substrate and a cathode substrate of a lithium ion secondary battery, an electrode substrate of a fuel cell, a catalyst support for a fuel cell, and the like, but is not particularly limited.

以下に実施例を挙げて本発明を具体的に説明するが、本発明はここに掲げる実施例によって限定されるものではない。   EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples listed here.

（カーボンナノチューブの合成）
Ｋ．Ｈｅｒｎａｄｉ、Ａ．Ｆｏｎｓｅｃａらによる報告を参照（Ｚｅｏｌｉｔｅｓ １７：４１６−４２３、１９９６）し、酢酸鉄（２ｇ）、酢酸コバルト（２ｇ）、Ｙ型ゼオライト（東ソー社製ＨＳＺ−３１０ＮＡＡ Ｌｏｔ．Ｎｏ．ＧＺ−１４３−３〜５）（１０ｇ）を秤量し、メタノール（１００ｍｌ）を加えて、振とう器にて１時間攪拌後、メタノール分を乾燥除去し、触媒を得た。次に、内径３２ｍｍの石英管の中央部の石英ウール上に、上記で調製した固体触媒１．０ｇをとり、窒素ガスを３０ｃｃ／分で供給した。窒素ガスの供給を続けながら、石英管を電気炉中に設置して、中心温度を６００℃に加熱した（昇温時間６０分）。６００℃に到達した後、窒素ガスの他に高純度アセチレンガス（高圧ガス工業製）を６ｃｃ／分で５時間供給した後、アセチレンガスの供給をやめ、温度を室温まで冷却し、反応物を取り出した。 (Synthesis of carbon nanotubes)
K. Hernadi, A.M. See the report by Fonseca et al. (Zeolites 17: 416-423, 1996), iron acetate (2 g), cobalt acetate (2 g), Y-type zeolite (HSZ-310NAA Lot. No. GZ-143-3 manufactured by Tosoh Corporation). 5) (10 g) was weighed, methanol (100 ml) was added, and after stirring for 1 hour with a shaker, the methanol content was removed by drying to obtain a catalyst. Next, 1.0 g of the solid catalyst prepared above was taken on quartz wool at the center of a quartz tube having an inner diameter of 32 mm, and nitrogen gas was supplied at 30 cc / min. While continuing the supply of nitrogen gas, the quartz tube was placed in an electric furnace, and the center temperature was heated to 600 ° C. (temperature rising time 60 minutes). After reaching 600 ° C., high-purity acetylene gas (manufactured by High Pressure Gas Industry) in addition to nitrogen gas is supplied at 6 cc / min for 5 hours, then the supply of acetylene gas is stopped, the temperature is cooled to room temperature, I took it out.

（カーボンナノチューブの確認）
上記で得られた触媒とカーボンナノチューブの混合物を、フッ化水素酸１０％水溶液中で３時間攪拌後、ろ紙（Ｔｏｙｏ Ｒｏｓｈｉ Ｋａｉｓｈａ、Ｆｉｌｔｅｒ Ｐａｐｅｒ ２号 １２５ｍｍ）を用いてろ過し、ろ紙上の固形物を、イオン交換水、アセトン溶液にて洗浄後、乾燥し、カーボンナノチューブを得た。得られたカーボンナノチューブを透過型電子顕微鏡で測定したところ、外径が２０ｎｍ以下で内径が５ｎｍ程度の細い中空状ナノファイバーが主成分であることがわかった。また、ＳＥＭのＥＤＸを用いて元素分析を行ったところ、Ｙ型ゼオライトの存在率はＥＤＸの測定限界以下（ほぼ０％）である結果を得た。さらに、共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、１．６であった。 (Confirmation of carbon nanotube)
The mixture of the catalyst and carbon nanotube obtained above was stirred in a 10% aqueous solution of hydrofluoric acid for 3 hours, and then filtered using a filter paper (Toyo Rossi Kaisha, Filter Paper No. 125 mm) to obtain a solid on the filter paper. Was washed with ion-exchanged water and an acetone solution and then dried to obtain carbon nanotubes. When the obtained carbon nanotube was measured with the transmission electron microscope, it turned out that the thin hollow nanofiber whose outer diameter is 20 nm or less and whose inner diameter is about 5 nm is a main component. Further, when elemental analysis was performed using EDX of SEM, the result was that the abundance of the Y-type zeolite was below the EDX measurement limit (approximately 0%). Furthermore, the Raman spectrum was measured with a resonance Raman spectrometer (INF-300 manufactured by Horiba Joban Yvon), and the G / D ratio was determined to be 1.6.

＜実施例１＞（ホウ酸処理）
上記で得られたカーボンナノチューブ０．４ｇを、３００ｍＬナスフラスコに測り取り、ホウ酸１９ｇ、水５０ｍＬを加え、８０℃で２時間撹拌しながら処理を行った。処理後、ろ取、水洗し、ホウ素処理した炭素材料を得た。得られたカーボンナノチューブを透過型電子顕微鏡で測定したところ、外径が２０ｎｍ以下で内径が５ｎｍ程度の細い中空状ナノファイバーが主成分であることがわかった。また、共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、２．２であった。 <Example 1> (Boric acid treatment)
0.4 g of the carbon nanotube obtained above was measured in a 300 mL eggplant flask, 19 g of boric acid and 50 mL of water were added, and the treatment was performed at 80 ° C. with stirring for 2 hours. After the treatment, it was filtered and washed with water to obtain a boron-treated carbon material. When the obtained carbon nanotube was measured with the transmission electron microscope, it turned out that the thin hollow nanofiber whose outer diameter is 20 nm or less and whose inner diameter is about 5 nm is a main component. Further, the Raman spectrum was measured with a resonance Raman spectrometer (INF-300 manufactured by Horiba Joban Yvon), and the G / D ratio was determined to be 2.2.

＜実施例２＞
（電界電子放出源の作成）
１００ｍｌビーカーに実施例１にて得られたカーボンナノチューブを５０ｍｇおよびアセトン１００ｍｌを入れ、超音波を３０分間照射した。本分散液を、これとは別に銅板を入れたビーカーに入れ、静置してアセトンを自然蒸発させることにより、表面にカーボンナノチューブを堆積させた銅板を得た。 <Example 2>
(Creation of field electron emission source)
50 mg of the carbon nanotube obtained in Example 1 and 100 ml of acetone were placed in a 100 ml beaker, and ultrasonic waves were irradiated for 30 minutes. Separately, this dispersion was placed in a beaker containing a copper plate, and allowed to stand to spontaneously evaporate acetone to obtain a copper plate having carbon nanotubes deposited on the surface.

（電界電子放出能の評価）
得られた銅板をカソードにしアノード電極と対向させ、この２極管構造物を評価用チャンバーに導入し、電界電子放出能を評価した。その結果、本実施例で得られたカーボンナノチューブは良好な電界電子放出能を示した。 (Evaluation of field electron emission ability)
The obtained copper plate was used as a cathode so as to face the anode electrode, and this bipolar structure was introduced into an evaluation chamber to evaluate the field electron emission ability. As a result, the carbon nanotubes obtained in this example showed good field electron emission ability.

＜実施例３＞
（触媒評価用電極の調製方法）
実施例１で得られたカーボンナノチューブにＰｔ、Ｒｕエタノール溶液を加えて混合した後、３０分間超音波処理して十分に分散させた後、乾燥した。その後、得られた粉末を水素／窒素（１：９）混合気体を流通させながら、２００℃で２時間熱分解を行いＰｔ−Ｒｕ／カーボンナノチューブ触媒を調製した。 <Example 3>
(Method for preparing electrode for catalyst evaluation)
The carbon nanotubes obtained in Example 1 were mixed with a Pt and Ru ethanol solution, and then subjected to ultrasonic treatment for 30 minutes to be sufficiently dispersed, and then dried. Thereafter, the obtained powder was pyrolyzed at 200 ° C. for 2 hours while flowing a hydrogen / nitrogen (1: 9) mixed gas to prepare a Pt—Ru / carbon nanotube catalyst.

本触媒にメタノールを加え、３０分間超音波にて均一に分散させた後、得られた分散液をグラッシーカーボン（ＧＣ）電極上に滴下し、乾燥させた。その後、メタノールで希釈した５％Ｎａｆｉｏｎ（登録商標）溶液（Ａｌｄｒｉｃｈ社製）を滴下し電極触媒を固定化、乾燥し、試験電極とした。   Methanol was added to the catalyst and uniformly dispersed with ultrasonic waves for 30 minutes, and then the obtained dispersion was dropped onto a glassy carbon (GC) electrode and dried. Thereafter, a 5% Nafion (registered trademark) solution (manufactured by Aldrich) diluted with methanol was added dropwise to immobilize and dry the electrode catalyst to obtain a test electrode.

（メタノール酸化電流値測定法）
メタノールを含む硫酸水溶液を電解液とした半電池による電極触媒のメタノール酸化活性を評価した。電解液に１Ｍとなるようにメタノールを加えた０．５Ｍ−硫酸水溶液を用いた。測定は電位ステップ定電位分極法により行った。このときのステップ電位は、７５ｍＶ（ｖｓ．ＲＨＥ（可逆水素電極））から５００ｍＶ（ｖｓ．ＲＨＥ）と変化させ、５００ｍＶに変化させてから３０分後の酸化電流値を触媒性能の目安として比較した。その結果、測定開始後３０分で２８Ａ／ｇ−Ｐｔを示した。 (Methanol oxidation current measurement method)
The methanol oxidation activity of the electrocatalyst by a half-cell using a sulfuric acid aqueous solution containing methanol as an electrolyte was evaluated. A 0.5 M-sulfuric acid aqueous solution in which methanol was added to the electrolytic solution to 1 M was used. The measurement was performed by the potential step constant potential polarization method. The step potential at this time was changed from 75 mV (vs. RHE (reversible hydrogen electrode)) to 500 mV (vs. RHE), and the oxidation current value 30 minutes after the change to 500 mV was compared as a measure of catalyst performance. . As a result, 28 A / g-Pt was shown 30 minutes after the start of measurement.

＜実施例４＞
市販の多層カーボンナノチューブ０．４ｇを用い、実施例１と同様にして、ホウ素処理した炭素材料を得た。得られたカーボンナノチューブを共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、１．０であった。 <Example 4>
A boron-treated carbon material was obtained in the same manner as in Example 1 using 0.4 g of commercially available multi-walled carbon nanotubes. The obtained carbon nanotube was measured by Raman spectroscopy with a resonance Raman spectrometer (INF-300 manufactured by Horiba Joban Yvon), and the G / D ratio was determined to be 1.0.

＜実施例５＞
市販の多層カーボンナノチューブ０．４ｇに６０％硝酸１２ｇと９６％硫酸１２０ｇを加え、１２０℃で１０分間処理し、水で５倍に希釈した後にろ取、水洗を行った。得られたカーボンナノチューブを共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、０．８であった。 <Example 5>
To 0.4 g of commercially available multi-walled carbon nanotubes, 12 g of 60% nitric acid and 120 g of 96% sulfuric acid were added, treated at 120 ° C. for 10 minutes, diluted 5 times with water, filtered and washed with water. The obtained carbon nanotube was measured by Raman spectroscopy with a resonance Raman spectrometer (INF-300 manufactured by Horiba Joban Yvon), and the G / D ratio was determined to be 0.8.

得られた前処理済み多層カーボンナノチューブを実施例１と同様にホウ酸で処理し、得られた多層カーボンナノチューブを共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、１．１であり、炭素質材料のグラファイト性が向上したことが分かった。   The obtained pretreated multi-walled carbon nanotubes were treated with boric acid in the same manner as in Example 1, and the obtained multi-walled carbon nanotubes were measured for Raman spectroscopy with a resonance Raman spectrometer (INF-300 manufactured by Horiba Jobin Yvon). When the / D ratio was determined, it was 1.1, indicating that the graphite property of the carbonaceous material was improved.

＜比較例１＞
市販の多層カーボンナノチューブを共鳴ラマン分光計（ホリバ ジョバンイボン製 ＩＮＦ−３００）でラマン分光を測定し、Ｇ／Ｄ比を求めたところ、０．８であった。 <Comparative Example 1>
A commercially available multi-walled carbon nanotube was measured by Raman spectroscopy with a resonance Raman spectrometer (INF-300 manufactured by Horiba Joban Yvon), and the G / D ratio was determined to be 0.8.

＜比較例２＞
ホウ素処理を行う前のカーボンナノチューブを用い、実施例３と同様に触媒を調製した。得られた触媒のメタノール酸化電流値を測定したところ、１５Ａ／ｇ−Ｐｔであった。 <Comparative example 2>
A catalyst was prepared in the same manner as in Example 3 using the carbon nanotubes before boron treatment. The methanol oxidation current value of the obtained catalyst was measured and found to be 15 A / g-Pt.

本発明で得られた炭素質材料は、電子放出材料、電池電極材料、燃料電池用触媒担体に限らず、燃料電池やリチウム２次電池用電極材、樹脂や有機半導体との複合材料からなる高強度樹脂、導電性樹脂、電磁波シールド材、走査型トンネル顕微鏡用プローブ、電界電子放出源、ナノピンセット、吸着材料、医療用ナノカプセル、ＭＲＩ造影剤などにも応用することができるが、その応用範囲が、これらに限られるものではない。   The carbonaceous material obtained in the present invention is not limited to an electron emission material, a battery electrode material, and a catalyst support for a fuel cell, but is a high material composed of a composite material of a fuel cell, an electrode material for a lithium secondary battery, a resin and an organic semiconductor. Can be applied to strength resins, conductive resins, electromagnetic shielding materials, scanning tunneling microscope probes, field electron emission sources, nanotweezers, adsorbing materials, medical nanocapsules, MRI contrast agents, etc. However, it is not limited to these.

実施例１で得たカーボンナノチューブのＴＥＭ写真（×１０００００）。3 is a TEM photograph (× 100,000) of the carbon nanotube obtained in Example 1. FIG.

Claims (11)

炭素質材料をホウ素を含む材料と共に６０℃以上５００℃以下の温度で処理することを特徴とする、炭素質材料の処理方法。 A method for treating a carbonaceous material, comprising treating a carbonaceous material together with a material containing boron at a temperature of 60 ° C. or higher and 500 ° C. or lower. ホウ素を含む材料として、酸化ホウ素、ホウ素、ホウ酸、および窒化ホウ素から選ばれる少なくとも一種を用いることを特徴とする、請求項１記載の炭素質材料の処理方法。 The method for treating a carbonaceous material according to claim 1, wherein at least one selected from boron oxide, boron, boric acid, and boron nitride is used as the material containing boron. ホウ素を含む材料と処理する際に、ホウ素を含む材料を溶液として用いることを特徴とする、請求項１または２記載の炭素質材料の処理方法。 The method for treating a carbonaceous material according to claim 1 or 2, wherein the material containing boron is used as a solution when the material containing boron is treated. 炭素質材料がカーボンナノチューブを含有することを特徴とする請求項１〜３のいずれかに記載の炭素質材料の処理方法。 The method for treating a carbonaceous material according to any one of claims 1 to 3, wherein the carbonaceous material contains carbon nanotubes. 含まれるカーボンナノチューブの総本数のうち、１０％以上が１〜５層であることを特徴とする、請求項４記載の炭素質材料の処理方法。 The method for treating a carbonaceous material according to claim 4, wherein 10% or more of the total number of carbon nanotubes contained is 1 to 5 layers. 炭素質材料をホウ素を含む材料と処理する前に、あらかじめ薬液によって処理しておくことを特徴とする請求項１〜５のいずれかに記載の炭素質材料の処理方法。 The carbonaceous material treatment method according to any one of claims 1 to 5, wherein the carbonaceous material is treated with a chemical solution in advance before the treatment with the material containing boron. 薬液が酸を含むことを特徴とする請求項６記載の炭素質材料の処理方法。 The method for treating a carbonaceous material according to claim 6, wherein the chemical solution contains an acid. ホウ素を含有し、カーボンナノチューブの総本数の１０％以上が層数１〜５層のカーボンナノチューブであることを特徴とする炭素質材料 A carbonaceous material containing boron, wherein 10% or more of the total number of carbon nanotubes is a carbon nanotube having 1 to 5 layers カーボンナノチューブの骨格中にホウ素を含有することを特徴とする請求項８記載の炭素質材料 9. The carbonaceous material according to claim 8, wherein boron is contained in the skeleton of the carbon nanotube. 請求項１〜７のいずれかに記載の方法で得られた炭素質材料または請求項８または９記載の炭素質材料を含有する電子放出材料。 An electron-emitting material containing the carbonaceous material obtained by the method according to claim 1 or the carbonaceous material according to claim 8 or 9. 請求項１〜７のいずれかに記載の方法で得られた炭素質材料または請求項８または９記載の炭素質材料を含有する電池電極材料。 The battery electrode material containing the carbonaceous material obtained by the method in any one of Claims 1-7, or the carbonaceous material of Claim 8 or 9.
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JP2007179867A (en) * 2005-12-28 2007-07-12 Hitachi High-Technologies Corp Electron source using fibrous carbon material
WO2008066123A1 (en) * 2006-11-30 2008-06-05 National Institute Of Advanced Industrial Science And Technology Biosensor utilizing carbon nanotube
JP2008300307A (en) * 2007-06-04 2008-12-11 Hitachi High-Technologies Corp Electron emitting element, electron gun, and electronic beam application device using the same
JP2017226595A (en) * 2016-06-15 2017-12-28 国立大学法人東北大学 Carbon material and method for producing the same

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007179867A (en) * 2005-12-28 2007-07-12 Hitachi High-Technologies Corp Electron source using fibrous carbon material
WO2008066123A1 (en) * 2006-11-30 2008-06-05 National Institute Of Advanced Industrial Science And Technology Biosensor utilizing carbon nanotube
JP2008157930A (en) * 2006-11-30 2008-07-10 National Institute Of Advanced Industrial & Technology Biosensor using carbon nanotube
JP2008300307A (en) * 2007-06-04 2008-12-11 Hitachi High-Technologies Corp Electron emitting element, electron gun, and electronic beam application device using the same
JP2017226595A (en) * 2016-06-15 2017-12-28 国立大学法人東北大学 Carbon material and method for producing the same
JP7092296B2 (en) 2016-06-15 2022-06-28 国立大学法人東北大学 Carbon material and its manufacturing method

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