JPH08231210A - Method for purifying carbon nanotube - Google Patents
Method for purifying carbon nanotubeInfo
- Publication number
- JPH08231210A JPH08231210A JP7311821A JP31182195A JPH08231210A JP H08231210 A JPH08231210 A JP H08231210A JP 7311821 A JP7311821 A JP 7311821A JP 31182195 A JP31182195 A JP 31182195A JP H08231210 A JPH08231210 A JP H08231210A
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- Prior art keywords
- carbon nanotubes
- nanotubes
- separated
- nanoparticles
- carbon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、カラム・クロマトグラ
フィ、超遠心分離、超音波粉砕などに様々な技術的方法
を用いて、カーボンナノチューブを他の炭素物質から分
離し、さらに分離したカーボン・ナノチューブを金属タ
イプのカーボン・ナノチューブと絶縁タイプのカーボン
・ナノチューブとに分離するナノチューブの精製法に関
する。本発明はカーボン・ナノチューブという新規の物
質を工業的、特に電気産業分野のために製造し、使用す
る上で有効である。BACKGROUND OF THE INVENTION The present invention relates to the separation of carbon nanotubes from other carbon substances using various technical methods such as column chromatography, ultracentrifugation, ultrasonic crushing, and the like. The present invention relates to a method for purifying nanotubes, which separates metal type carbon nanotubes and insulating type carbon nanotubes. INDUSTRIAL APPLICABILITY The present invention is effective in producing and using a novel substance called carbon nanotube for industrial use, particularly for the electric industry field.
【０００２】[0002]
【従来の技術】カーボン・ナノチューブは１９９１年
（Ｎａｔｕｒｅ，３５４，５６−５８，１９９１）に発
見されて以来、１次元細線、触媒など種々の潜在的な応
用が期待される新しい材料として世界中の注目を浴びて
いる。最近、我々はカーボン・ナノチューブを大量に合
成できる製造方法（特願平４−１７２２４２号）につい
て報告している。2. Description of the Related Art Since carbon nanotubes were discovered in 1991 (Nature, 354, 56-58, 1991), they have been used around the world as new materials expected to have various potential applications such as one-dimensional thin wires and catalysts. It is in the spotlight. Recently, we have reported a manufacturing method (Japanese Patent Application No. 4-172242) capable of synthesizing a large amount of carbon nanotubes.
【０００３】不活性ガスで満たされた容器の中で炭素ア
ーク放電を起こさせると、Ｃ，Ｃ2，Ｃ3 などの炭素種
を含んだプラズマが発生する。これら小さな炭素種は次
第に凝縮し、煤、フラーレン、ナノチューブ、ナノ粒
子、さらに高密度の固体の炭素物質などのより大きい構
造に成長してゆく。我々は既に、ナノチューブの収率
が、それらを生成させる反応容器内の不活性ガスの圧力
に決定的に依存することを明らかにしている。不活性ガ
スの圧力が５００から２５００ｔｏｒｒの範囲にある場
合、ナノチューブの収率は最も高くなる。When a carbon arc discharge is generated in a container filled with an inert gas, a plasma containing carbon species such as C, C 2 and C 3 is generated. These small carbon species gradually condense and grow into larger structures such as soot, fullerenes, nanotubes, nanoparticles, and even dense solid carbonaceous materials. We have already shown that the yield of nanotubes is critically dependent on the pressure of the inert gas in the reaction vessel in which they are produced. The highest yield of nanotubes is obtained when the pressure of the inert gas is in the range of 500 to 2500 torr.
【０００４】[0004]
【発明が解決しようとする課題】しかし、最適条件下で
も、ナノ粒子はナノチューブとともに生成してしまい、
時には、ガラス状炭素やアモルファス炭素などの他の炭
素物質を同時に生成する。従って、ナノチューブを利用
するためには、合成後にこれらのナノチューブ以外の炭
素物質を分離する必要がある。However, even under the optimum conditions, nanoparticles are produced together with the nanotubes,
At times, other carbon materials such as glassy carbon and amorphous carbon are produced at the same time. Therefore, in order to utilize the nanotubes, it is necessary to separate carbon substances other than these nanotubes after the synthesis.
【０００５】現在までのところ、ナノチューブをナノ粒
子、他の炭素物質から分離する方法は報告されていな
い。また電気伝導度に関して均一なカーボン・ナノチュ
ーブも今までのところ精製されていない。To date, no method has been reported for separating nanotubes from nanoparticles, other carbonaceous materials. Also, carbon nanotubes that are uniform in electrical conductivity have not been refined so far.
【０００６】そこで本発明は、分子量、大きさおよび電
気伝導度に関して均一である良質のナノチューブ材料を
得ることを目的とする。It is therefore an object of the present invention to obtain a good quality nanotube material which is uniform in molecular weight, size and electrical conductivity.
【０００７】[0007]
【課題を解決するための手段】本発明は、カラムクロマ
トグラフィー、超遠心分離、超音波粉砕、膜分離などの
技術、ならびに界面活性剤の利用により、ナノチューブ
のサイズ分布を狭域化して、カーボンナノチューブを含
む粗生成物からカーボン・ナノチューブを精製および分
離し、分離された前記カーボン・ナノチューブを、回転
ドラムにばらまき、電子ビームの照射またはコロナ放電
シャワーを浴びせることによりカーボン・ナノチューブ
を帯電させ、回転ドラムを回転させることにより、帯電
しなかった金属タイプのカーボン・ナノチューブを回転
ドラムから除き、それによって金属タイプのカーボンナ
ノチューブと絶縁タイプのカーボン・ナノチューブとに
分離することを特徴とするカーボン・ナノチューブの精
製方法である。The present invention aims at narrowing the size distribution of nanotubes by using techniques such as column chromatography, ultracentrifugation, ultrasonic crushing, membrane separation and the like, and carbon nanotubes. The carbon nanotubes are purified and separated from the crude product containing the nanotubes, and the separated carbon nanotubes are scattered on a rotating drum, and the carbon nanotubes are charged by rotating the drum by electron beam irradiation or a corona discharge shower to rotate the carbon nanotubes. By rotating the drum, the uncharged metal-type carbon nanotubes are removed from the rotating drum, thereby separating the metal-type carbon nanotubes and the insulating-type carbon nanotubes. This is a purification method.
【０００８】はじめに、カーボン・ナノチューブを含む
粗生成物からカーボン・ナノチューブを分離する方法に
ついて説明する。First, a method for separating carbon nanotubes from a crude product containing carbon nanotubes will be described.
【０００９】合成されたナノチューブを含む粗生成物を
原子間力顕微鏡（ＡＦＭ）で観測すると、ナノチューブ
だけが密に詰まった束状繊維部分、ナノ粒子、ガラス状
炭素やアモルファス炭素などの無定型炭素から構成され
ていることが分かる。ナノチューブの束状繊維構造は、
微細であることと比較的強固であるため、通常の力学的
粉砕では破壊できない。束状繊維構造の破壊には超音波
粉砕が有効である。超音波の周波数を２８ｋＨｚ、４５
ｋＨｚ、１００ｋＨｚの３種類組み合わせて使用するこ
とにより、ナノチューブの束状繊維構造を完全に粉砕す
ることが可能である（この事実は、ＡＦＭの観察から明
らかになった）。溶媒中に超音波で分散させた場合、ナ
ノチューブおよびナノ粒子以外の炭素物質は、界面活性
剤を使用してもしなくとも、濾過のみでナノチューブお
よびナノ粒子から分離することが可能である。ナノチュ
ーブの精製において、界面活性剤は次の段階で特別な働
きをする。界面活性剤を使用するとナノチューブおよび
ナノ粒子を溶媒中に完全に分散させること、すなわち溶
媒和させることが可能となる。もし、界面活性剤を添加
しないと、ナノチューブ（およびナノ粒子）は、超音波
の供給を一旦止めてしまうと同時に凝縮を始めてしま
う。従って、界面活性剤の使用は、ナノチューブの可溶
化に不可欠である。When the crude product containing the synthesized nanotubes is observed by an atomic force microscope (AFM), a bundle-like fiber portion in which only the nanotubes are densely packed, nanoparticles, amorphous carbon such as glassy carbon or amorphous carbon is observed. You can see that it is composed of. The bundled fiber structure of nanotubes is
Since it is fine and relatively strong, it cannot be destroyed by ordinary mechanical crushing. Ultrasonic crushing is effective for breaking the bundled fiber structure. The ultrasonic frequency is 28 kHz, 45
By using a combination of three types of kHz and 100 kHz, it is possible to completely crush the bundled fiber structure of nanotubes (this fact was made clear by the observation of AFM). When ultrasonically dispersed in a solvent, carbon materials other than nanotubes and nanoparticles can be separated from nanotubes and nanoparticles by filtration alone, with or without the use of surfactants. Surfactants play a special role in the next step in the purification of nanotubes. The use of surfactants allows the nanotubes and nanoparticles to be completely dispersed, ie solvated, in a solvent. If no surfactant is added, the nanotubes (and nanoparticles) will begin to condense at the same time that the ultrasonic wave is turned off. Therefore, the use of surfactants is essential for the solubilization of nanotubes.
【００１０】さらに、カラム・クロマトグラフィ法によ
り、ナノ粒子からナノチューブ分離することが可能であ
る。この方法の中でも、物質をその大きさの相違により
分離するサイズ排除カラム・クロマトグラフィ法が特に
有効である。一般にサイズ排除カラム・クロマトグラフ
ィ法は、タンパク質、核酸や糖類などの生体高分子の分
離に用いられる。本発明は炭素のみで構成される超微結
晶（ただし、分子量的には巨大）であるナノチューブの
精製にこの方法を適用する。Furthermore, it is possible to separate nanotubes from nanoparticles by a column chromatography method. Among these methods, the size exclusion column chromatography method, which separates substances according to their size differences, is particularly effective. Generally, the size exclusion column chromatography method is used for separating biopolymers such as proteins, nucleic acids and saccharides. The present invention applies this method to the purification of nanotubes which are ultra-fine crystals (however, huge in terms of molecular weight) composed only of carbon.
【００１１】また、濃度勾配超遠心分離による方法は、
ナノチューブ、ナノ粒子、その他の炭素物質がそれぞれ
異なった形状、大きさおよび比重を持つことを利用し、
それぞれを分離する。透過型電子顕微鏡（ＴＥＭ）およ
びＡＦＭによって観察を行うと、ナノチューブはアスペ
クト比の大きな針状構造、ナノ粒子は球状構造、ガラス
状炭素、アモルファス炭素は無定型構造と直流アーク放
電法で合成される粗生成物の各成分は全く異なる形状と
大きさを有することが認められ、また、それぞれの構造
の相違に由来して比重も異なる（ナノ粒子の比重＞ナノ
チューブの比重＞無定型炭素の比重≒１．７ｇ・ｃ
ｍ-2）。これらの実験事実に基づき、ナノチューブをナ
ノ粒子、無定型炭素から分離することに超遠心を応用す
ることを考案し、その有効性を実証した。さらに、分離
されたナノチューブの超遠心分離を何度か繰り返すこと
により、ナノチューブ自体をその大きさによって分離す
ることも可能である。The method using concentration gradient ultracentrifugation is
Utilizing the fact that nanotubes, nanoparticles, and other carbon materials have different shapes, sizes, and specific gravities,
Separate each. When observed by a transmission electron microscope (TEM) and an AFM, nanotubes are synthesized by a direct current arc discharge method with a needle-shaped structure having a large aspect ratio, nanoparticles are spherical structures, glassy carbon, and amorphous carbon are amorphous structures and a direct current arc discharge method. It is recognized that each component of the crude product has a completely different shape and size, and the specific gravity is different due to the difference in each structure (nanoparticle specific gravity> nanotube specific gravity> amorphous carbon specific gravity ≈ 1.7 g / c
m -2 ). Based on these experimental facts, we devised to apply ultracentrifugation to the separation of nanotubes from nanoparticles and amorphous carbon, and demonstrated its effectiveness. Furthermore, by repeating ultracentrifugation of the separated nanotubes several times, the nanotubes themselves can be separated according to their size.
【００１２】理論的な研究によると、カーボン・ナノチ
ューブはその直径および螺旋度に応じて、金属もしくは
絶縁体（バンドギャップの大きい半導体）になる（Ｐｈ
ｙｓ．Ｒｅｖ．Ｌｅｔｔｅｒｓ ６８，１５７９−１５
８１，１９９２）。それで我々は、ナノチューブの電気
的性質に基づくナノチューブ分離の技術を発明した。こ
の方法は金属タイプと絶縁体タイプのナノチューブの帯
電の仕方の違いを利用している。すなわち、ナノチュー
ブを含むサンプルを回転ドラムに乗せ、それに電子ビー
ムを照射、もしくはコロナ放電シャワーを浴びせ、サン
プルが帯電できる条件にする。このドラムを回転させる
と、金属タイプのナノチューブは帯電できないのでドラ
ムから滑り落ちる。絶縁体タイプのナノチューブは帯電
した状態にあるのでドラムに静電力で引きつけられ、ド
ラムの回転で滑り落ちることはない。従って、この方法
は金属タイプのナノチューブと絶縁体タイプのナノチュ
ーブを分離する上で非常に有効である。Theoretical studies have shown that carbon nanotubes can be metals or insulators (semiconductors with a large bandgap) depending on their diameter and spiralness (Ph.
ys. Rev. Letters 68, 1579-15
81, 1992). So we invented a technique for nanotube separation based on the electrical properties of nanotubes. This method takes advantage of the difference in charging method between metal type and insulator type nanotubes. That is, a sample containing nanotubes is placed on a rotating drum, and an electron beam is applied to the sample or a corona discharge shower is applied to the sample so that the sample is charged. When the drum is rotated, the metal type nanotubes cannot be charged and will slide off the drum. Since the insulator type nanotube is charged, it is attracted to the drum by electrostatic force and does not slide down by the rotation of the drum. Therefore, this method is very effective in separating metal type nanotubes and insulator type nanotubes.
【００１３】さらに、均一性の高い、良質のナノチュー
ブを得ることは、ナノチューブを工業的に利用する上で
必要不可欠なことである。前述の分離方法を組み合わせ
ることにより、分子量、大きさ、電気伝導性に関して均
一である良質のナノチューブを得ることが可能となる。
従って、本発明の工業的利用価格は非常に大きい。Furthermore, obtaining nanotubes of high quality with high uniformity is essential for industrial application of nanotubes. By combining the above-mentioned separation methods, it becomes possible to obtain high-quality nanotubes having uniform molecular weight, size, and electrical conductivity.
Therefore, the industrial use price of the present invention is very high.
【００１４】[0014]
【実施例】はじめに、カーボン・ナノチューブを含む粗
生成物からカーボン・ナノチューブを分離する方法（１
〜４）について説明する。EXAMPLES First, a method for separating carbon nanotubes from a crude product containing carbon nanotubes (1
4) will be described.
【００１５】１）カラム・クロマトグラフィ法によるナ
ノチューブの分離精製 クロマトグラフィ用カラムにＳｅｐｈａｒｏｓｅ Ｃ１
（Ｐｈａｒｍａｃｉａ社製）クロマトグラフィ・ゲルを
エタノールとともに充填する。ナノチューブとナノ粒子
を含む試料をエタノール中で超音波分散により懸濁さ
せ、その懸濁溶液をカラムに通す。その時、ナノチュー
ブとナノ粒子以外の炭素物質はゲル上部に残り、ナノチ
ューブとナノ粒子ときれいに分散できる。ナノチューブ
とナノ粒子は展開液とともにゲル中に展開する。そし
て、分子量、形状に由来する展開速度の相違により、ナ
ノチューブはナノ粒子から分離される。さらに、この方
法を用いることにより、分子量の異なるナノチューブを
分離することができる。結果の一部を表１に示す。ま
た、東ソー製のＴＳＫｇｅＩセルロースＣＷまたはメタ
ノール、アセトンなどをゲル濾過クロマトグラフィの充
填剤として用い、ドデシル硫酸ナトリウム（ＳＤＳ）な
どの界面活性剤を展開液として用いても、上記と同様に
ナノチューブの分離を行うことが出来る。1) Separation and Purification of Nanotubes by Column Chromatography Sepharose C1 is used as a column for chromatography.
A chromatography gel (Pharmacia) is filled with ethanol. A sample containing nanotubes and nanoparticles is suspended in ethanol by ultrasonic dispersion and the suspension solution is passed through a column. At that time, carbon substances other than the nanotubes and the nanoparticles remain on the upper part of the gel, and the nanotubes and the nanoparticles can be dispersed well. Nanotubes and nanoparticles spread in the gel with the developing solution. Then, the nanotubes are separated from the nanoparticles due to the difference in the development speed derived from the molecular weight and the shape. Furthermore, by using this method, nanotubes having different molecular weights can be separated. Some of the results are shown in Table 1. Also, TSKgeI cellulose CW manufactured by Tosoh or methanol, acetone or the like is used as a packing material for gel filtration chromatography, and a surfactant such as sodium dodecyl sulfate (SDS) is used as a developing solution to separate nanotubes in the same manner as above. You can do it.
【００１６】[0016]
【表１】 [Table 1]
【００１７】２）超音波粉砕、分離膜を用いたナノチュ
ーブの分離精製 ナノチューブ・ナノ粒子を含む試料をエタノールに懸濁
させ、超音波粉砕する。ナノチューブ・ナノ粒子以外の
比較的粒子径の大きな炭素物質はガラスフィルター（孔
径１０μｍ）で予備的に分離する。次に、得られたナノ
チューブ・ナノ粒子のエタノール溶液はメンブランフィ
ルター（Ｍｉｌｉｐｏｒｅ社製）に通す。この時、ま
ず、ボアサイズ（孔径）が８μｍのフィルターを用いて
ナノチューブ・ナノ粒子の膜分離を行い、その後、濾過
された溶液を順次ボアサイズが３μｍ、１．２μｍ、
０．４５μｍ、０．２２μｍのフィルターで濾過してゆ
く。この一連の膜分離に基づく濾過操作により、ナノチ
ューブ（サブμｍから十数μｍ）とナノ粒子（直径数ｎ
ｍから数十ｎｍ）を選択的に分離することが可能であ
る。各々の操作で分離膜上に残ったナノチューブ、ナノ
粒子について、表２に記す。さらに、長さの短いナノチ
ューブと長いナノチューブも分離できる。一連の濾過操
作に用いるフィルターのボアサイズの間隔を細かくする
ことにより、より選択的な分離も可能である。2) Ultrasonic pulverization, separation and purification of nanotubes using a separation membrane A sample containing nanotubes / nanoparticles is suspended in ethanol and ultrasonically pulverized. Carbon materials with a relatively large particle size other than nanotubes / nanoparticles are preliminarily separated with a glass filter (pore size 10 μm). Next, the obtained ethanol solution of nanotubes / nanoparticles is passed through a membrane filter (manufactured by Millipore). At this time, first, the nanotube / nanoparticles are separated into membranes using a filter having a pore size (pore size) of 8 μm, and then the filtered solution is sequentially subjected to a pore size of 3 μm, 1.2 μm,
Filter with 0.45 μm and 0.22 μm filters. By the filtration operation based on this series of membrane separation, nanotubes (sub-μm to tens of μm) and nanoparticles (diameter n)
m to several tens of nm) can be selectively separated. Table 2 shows the nanotubes and nanoparticles remaining on the separation membrane in each operation. Furthermore, short and long nanotubes can be separated. A more selective separation is also possible by narrowing the intervals of the filter bore sizes used in a series of filtration operations.
【００１８】フィルターとしては、ミクロフィルター
（富士フィルム社製）、メンブランフィルター（東洋社
製）等を用いることができる。As the filter, a micro filter (manufactured by Fuji Film Co., Ltd.), a membrane filter (manufactured by Toyo Co., Ltd.) or the like can be used.
【００１９】[0019]
【表２】 [Table 2]
【００２０】３）超遠心分離によるナノチューブの分離 まず、水にナノチューブ・ナノ粒子を含む試料を懸濁さ
せる。この時、ナノチューブ・ナノ粒子以外の比較的粒
子径が大きい炭素物質をガラスフィルターで取り除いて
おく。遠心管に密度勾配をつけたショ糖水溶液もしくは
塩化セシウム水溶液を入れ、その上に試料水溶液を乗せ
る。この遠心管を遠心分離機に入れ、遠心を行う。超遠
心は回転数５００ｒｐｍ（毎分５００回転）から５００
００ｒｐｍ、遠心時間は３０分から９６時間の間で行っ
た。分離された区画部分はピペットで慎重に採取する方
法、もしくは遠心管内部を液体窒素で冷却凍結させ輪切
りにして分離する方法で、遠心管から試料を取り出し
た。例えば、低速（５００ｒｐｍ）、短時間（３０分）
の超遠心で、まず、ナノチューブ、ナノ粒子以外の炭素
物質を取り除き、次に、中速（１０００ｒｐｍ）の超遠
心でナノチューブとナノ粒子を分離する。さらに、分取
されたナノチューブを適当な回転数、遠心時間のもとで
超遠心を行うと、ナノチューブを直径と長さの違いによ
り、分離することが出来る。この結果を表３−１、表３
−２に示す。3) Separation of Nanotubes by Ultracentrifugation First, a sample containing nanotubes / nanoparticles is suspended in water. At this time, carbon substances having a relatively large particle size other than the nanotubes / nanoparticles are removed by a glass filter. Put a sucrose aqueous solution or cesium chloride aqueous solution with a density gradient in a centrifuge tube, and place the sample aqueous solution on it. The centrifuge tube is placed in a centrifuge and centrifuged. Ultracentrifugation is from 500 rpm (500 rpm) to 500
The centrifugation was performed at 00 rpm for 30 minutes to 96 hours. A sample was taken out from the centrifuge tube by a method of carefully collecting the separated section with a pipette or by a method of cooling and freezing the inside of the centrifuge tube by freezing with liquid nitrogen and cutting into slices. For example, low speed (500 rpm), short time (30 minutes)
First, the carbon substances other than the nanotubes and nanoparticles are removed by ultracentrifugation, and then the nanotubes and nanoparticles are separated by medium speed (1000 rpm) ultracentrifugation. Furthermore, when the separated nanotubes are subjected to ultracentrifugation at an appropriate rotation speed and centrifugation time, the nanotubes can be separated due to the difference in diameter and length. The results are shown in Tables 3-1 and 3
-2.
【００２１】[0021]
【表３】 [Table 3]
【００２２】[0022]
【表４】 [Table 4]
【００２３】４）界面活性剤を用いたナノチューブの分
離精製 アーク放電で得られるナノチューブ、ナノ粒子を含む生
成物は、一般に知られているどの溶媒にも全く溶解しな
い。この性質はナノチューブの分離精製を困難なものに
している。しかし、溶媒に界面活性剤を添加することに
より、溶媒に対してナノチューブ、ナノ粒子を可溶化す
ることが可能である。この可溶化はナノチューブもしく
はナノ粒子と界面活性剤分子がミセルを形成することに
より、親溶媒コロイドとして溶媒中に分散することがで
きることに基づいている。この界面活性剤によるナノチ
ューブの可溶化を利用して、ナノチューブをナノ粒子や
他の炭素物質との分離を行う。例を挙げると、水では界
面活性剤としてドデシルスルホン酸ナトリウム（ＳＤ
Ｓ）が利用できる。水１０００ｃｍ3 に対して、ナノチ
ューブを含む試料を１００ｍｇを入れ、ＳＤＳを２×１
０-2モル（約５．７７ｇ）を添加し、超音波粉砕を施
す。ナノチューブとナノチューブ以外の粒子径の比較的
大きな炭素物質をガラスフィルターで除去することによ
り、試料は親水コロイドとして水に完全に溶ける。ＳＤ
Ｓ、トリ−ｎ−オクチルフォスフィンオキシド、アルキ
ルベンゼンスルフォン酸ナトリウム、２−スルホコハク
酸ジアルキルアミド、アルキルトリメチルアンモニウム
ハライド、アルキルポリオキシエチレンエーテル、脂肪
酸多価アルコールエステル、ｐ−アルキルフェニルポリ
オキシエチレンエーテルなどの適当な界面活性剤を選択
すれば、他の溶媒でもナノチューブを可溶化できる。4) Separation and Purification of Nanotubes Using Surfactant The products containing nanotubes and nanoparticles obtained by arc discharge do not dissolve at all in any commonly known solvent. This property makes separation and purification of nanotubes difficult. However, it is possible to solubilize nanotubes and nanoparticles in a solvent by adding a surfactant to the solvent. This solubilization is based on the fact that nanotubes or nanoparticles and surfactant molecules can be dispersed in a solvent as a solvophilic colloid by forming micelles. By utilizing the solubilization of nanotubes by this surfactant, the nanotubes are separated from nanoparticles and other carbon substances. For example, in water, sodium dodecyl sulfonate (SD
S) is available. Add 100 mg of the sample containing nanotubes to 1000 cm 3 of water, and add 2 × 1 SDS.
Add 0 -2 mol (about 5.77 g) and sonicate. The sample is completely dissolved in water as a hydrocolloid by removing the nanotube and the carbon material having a relatively large particle size other than the nanotube with a glass filter. SD
S, tri-n-octylphosphine oxide, sodium alkylbenzene sulfonate, 2-sulfosuccinic acid dialkylamide, alkyl trimethyl ammonium halide, alkyl polyoxyethylene ether, fatty acid polyhydric alcohol ester, p-alkylphenyl polyoxyethylene ether, etc. Nanotubes can be solubilized in other solvents by selecting an appropriate surfactant.
【００２４】また、ポリビニルアルコールなどの高分子
液体は、それ自身が界面活性剤としての性質を持つ。従
って、高分子液体中に、他の界面活性剤を添加すること
なく、ナノチューブ、ナノ粒子をコロイドとして分散さ
せることが可能である。The polymer liquid such as polyvinyl alcohol itself has a property as a surfactant. Therefore, it is possible to disperse the nanotubes and nanoparticles as a colloid in the polymer liquid without adding another surfactant.
【００２５】上記（１）〜（４）の方法により分離され
たカーボン・ナノチューブから、電気伝導性に関して均
一なナノチューブを得る本発明の一実施例を図面を用い
て説明する。An embodiment of the present invention for obtaining a nanotube having uniform electric conductivity from the carbon nanotubes separated by the above methods (1) to (4) will be described with reference to the drawings.
【００２６】（ナノチューブの電気的特性による分離精
製）静電分離に用いる装置は自作した。この装置は、図
１に示すように排気装置１、ガス導入装置２、電子ビー
ムまたはコロナ放電装置３、回転ドラム４とその周辺部
品、およびそれら可動部分の制御装置５、試料室６、分
離試料受け入れ室７、８で構成される。分離するサンプ
ルは予備的に高温、高真空下で脱気乾燥する。そのサン
プルを試料室６に入れ、回転ドラム４上に均一にばらま
く。そして、試料に電子ビームの照射またはコロナ放電
シャワーを浴びせ、ドラム４を回転させる。この時、金
属タイプのナノチューブは帯電していないので９０°回
転させたところで真下の試料受け入れ室に滑り落ちてゆ
く。一方、絶縁体タイプのナノチューブは帯電している
ので、ドラムに静電引力で引きつけられ滑り落ちない。
絶縁タイプのナノチューブはドラムが２７０°回転した
ところで試料を掻き落とす。分離されたナノチューブ各
々について上記操作を順次繰り返すと、より電気伝導度
に関して分離度の高いナノチューブが得られる。表４に
分離されたナノチューブの電気伝導度を示す。(Separation and Purification Based on Electrical Properties of Nanotubes) An apparatus used for electrostatic separation was self-made. As shown in FIG. 1, this device includes an exhaust device 1, a gas introduction device 2, an electron beam or corona discharge device 3, a rotary drum 4 and its peripheral parts, and a control device 5 for these movable parts, a sample chamber 6, and a separated sample. It is composed of receiving rooms 7 and 8. The sample to be separated is preliminarily degassed and dried under high temperature and high vacuum. The sample is placed in the sample chamber 6 and scattered evenly on the rotary drum 4. Then, the sample is irradiated with an electron beam or exposed to a corona discharge shower, and the drum 4 is rotated. At this time, since the metal type nanotube is not charged, it slides down into the sample receiving chamber directly below when rotated by 90 °. On the other hand, since insulator type nanotubes are charged, they are attracted to the drum by electrostatic attraction and do not slip off.
The insulating type nanotube scrapes the sample when the drum rotates 270 °. By repeating the above operation for each of the separated nanotubes, a nanotube having a higher degree of separation in terms of electric conductivity can be obtained. Table 4 shows the electrical conductivity of the separated nanotubes.
【００２７】[0027]
【表５】 [Table 5]
【００２８】上記１）、２）、３）、４）の精製法を用
いてナノチューブを大きさと分子量に関して分離精製を
行った後、本発明のナノチューブの電気的性質を用いた
方法で精製分離を行えば、大きさと分子量に関して均一
な絶縁タイプもしくは金属タイプのナノチューブを得る
ことができる。After the nanotubes are separated and purified in terms of size and molecular weight using the purification methods 1), 2), 3), and 4) above, they are purified and separated by the method using the electrical properties of the nanotubes of the present invention. If done, it is possible to obtain insulating type or metal type nanotubes that are uniform in size and molecular weight.
【００２９】[0029]
【発明の効果】本発明により、分子量、大きさおよび電
気伝導度に関して均一である良質のカーボン・ナノチュ
ーブを分離精製することができる。Industrial Applicability According to the present invention, it is possible to separate and purify good-quality carbon nanotubes having uniform molecular weight, size and electric conductivity.
【図面の簡単な説明】[Brief description of drawings]
【図１】本発明の静電分離に用いる装置を示す図であ
る。FIG. 1 is a diagram showing an apparatus used for electrostatic separation of the present invention.
１ 排気装置 ２ ガス導入装置 ３ 電子ビームまたはコロナ放電装置 ４ 回転ドラム ６ 試料室 ７ 分離試料受け入れ室１ ８ 分離試料受け入れ室２ ９ 試料落とし 1 Exhaust device 2 Gas introduction device 3 Electron beam or corona discharge device 4 Rotating drum 6 Sample chamber 7 Separated sample receiving chamber 1 8 Separated sample receiving chamber 2 9 Sample drop
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｄ０１Ｆ 9/127 Ｄ０１Ｆ 9/127 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location D01F 9/127 D01F 9/127
Claims (4)
を溶媒中に超音波を用いて分散させ、その溶液をクロマ
トグラフィ用カラムに通すことによりナノチューブとナ
ノ粒子以外の炭素物質を分離し、さらに、ナノチューブ
とナノ粒子の分子量、形状の差によるカラム中での展開
速度の相違により、カラム・クロマトグラフィを用いて
カーボン・ナノチューブを分離し、分離された前記カー
ボン・ナノチューブを、回転ドラムにばらまき、電子ビ
ームの照射またはコロナ放電シャワーを浴びせることに
よりカーボン・ナノチューブと帯電させ、回転ドラムを
回転させることにより、帯電しなかった金属タイプのカ
ーボン・ナノチューブを回転ドラムから除くことにより
金属タイプのカーボンナノチューブと絶縁タイプのカー
ボン・ナノチューブとに分離することを特徴とするカー
ボン・ナノチューブの精製方法。1. A crude product containing carbon nanotubes is dispersed in a solvent using ultrasonic waves, and the solution is passed through a column for chromatography to separate nanotubes and carbon substances other than nanoparticles. Due to the difference in the development speed in the column due to the difference in the molecular weight and shape of nanoparticles and nanoparticles, the carbon nanotubes are separated using column chromatography, and the separated carbon nanotubes are scattered on a rotating drum to generate an electron beam. The carbon nanotubes are charged by irradiation or showering with a corona discharge, and the rotating drum is rotated to remove the uncharged metal-type carbon nanotubes from the rotating drum. carbon nanotube A method for purifying carbon nanotubes, which comprises separating into
を溶媒中に超音波を用いて分散させ、その溶液をマイク
ロメートルからナノメートルオーダーの所望の孔径を有
する膜でろ過することによりカーボン・ナノチューブを
分離し、分離された前記カーボン・ナノチューブを、回
転ドラムにばらまき、電子ビームの照射またはコロナ放
電シャワーを浴びせることによりカーボン・ナノチュー
ブを帯電させ、回転ドラムを回転させることにより、帯
電しなかった金属タイプのカーボン・ナノチューブを回
転ドラムから除くことにより金属タイプのカーボンナノ
チューブと絶縁タイプのカーボン・ナノチューブとに分
離することを特徴とするカーボン・ナノチューブの精製
方法。2. The carbon nanotubes are obtained by dispersing the crude product containing the carbon nanotubes in a solvent using ultrasonic waves and filtering the solution through a membrane having a desired pore size on the order of micrometers to nanometers. Separated, the separated carbon nanotubes are scattered on a rotating drum, and the carbon nanotubes are charged by irradiating with an electron beam or by showering with a corona discharge, and by rotating the rotating drum, a metal type that is not charged A method for purifying carbon nanotubes, characterized in that the carbon nanotubes are separated from metal type carbon nanotubes and insulating type carbon nanotubes by removing the carbon nanotubes from the rotating drum.
を溶媒中に超音波を用いて分散させ、その溶液から遠心
分離機を用いてカーボンナノチューブを分離し、分離さ
れた前記カーボン・ナノチューブを、回転ドラムにばら
まき、電子ビームの照射またはコロナ放電シャワーを浴
びせることによりカーボン・ナノチューブを帯電させ、
回転ドラムを回転させることにより、帯電しなかった金
属タイプのカーボン・ナノチューブを回転ドラムから除
くことにより金属タイプのカーボンナノチューブと絶縁
タイプのカーボン・ナノチューブとに分離することを特
徴とするカーボン・ナノチューブの精製方法。3. A crude product containing carbon nanotubes is dispersed in a solvent using ultrasonic waves, the carbon nanotubes are separated from the solution using a centrifuge, and the separated carbon nanotubes are rotated. The carbon nanotubes are charged by being scattered on a drum and being exposed to an electron beam or a corona discharge shower.
By rotating the rotating drum, the non-charged metal type carbon nanotubes are removed from the rotating drum to separate the metal type carbon nanotubes from the insulating type carbon nanotubes. Purification method.
ューブの精製方法において、カーボンナノチューブを含
む粗生成物を溶媒中に超音波を用いて分散させる際に、
界面活性剤を添加することを特徴とするカーボンナノチ
ューブの精製方法。4. The method for purifying carbon nanotubes according to claim 1, wherein when the crude product containing carbon nanotubes is dispersed in a solvent using ultrasonic waves,
A method for purifying carbon nanotubes, which comprises adding a surfactant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7311821A JP2735055B2 (en) | 1995-11-30 | 1995-11-30 | Purification method of carbon nanotube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7311821A JP2735055B2 (en) | 1995-11-30 | 1995-11-30 | Purification method of carbon nanotube |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5014387A Division JP2522469B2 (en) | 1993-02-01 | 1993-02-01 | Carbon nanotube refining method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08231210A true JPH08231210A (en) | 1996-09-10 |
| JP2735055B2 JP2735055B2 (en) | 1998-04-02 |
Family
ID=18021815
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7311821A Expired - Lifetime JP2735055B2 (en) | 1995-11-30 | 1995-11-30 | Purification method of carbon nanotube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2735055B2 (en) |
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