JP5679939B2 - Method for removing catalytic metal - Google Patents

Method for removing catalytic metal Download PDF

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JP5679939B2
JP5679939B2 JP2011211702A JP2011211702A JP5679939B2 JP 5679939 B2 JP5679939 B2 JP 5679939B2 JP 2011211702 A JP2011211702 A JP 2011211702A JP 2011211702 A JP2011211702 A JP 2011211702A JP 5679939 B2 JP5679939 B2 JP 5679939B2
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和志 平岡
和志 平岡
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Hitachi Zosen Corp
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本発明は、触媒金属の除去方法に関するものである。   The present invention relates to a method for removing a catalytic metal.

カーボンナノチューブの形成方法としては、ＣＶＤ法、すなわち、基板に鉄触媒などの触媒金属を塗布した上で原料ガスを供給し、当該触媒金属上にカーボンナノチューブを成長させていく方法などがある。ＣＶＤ法によると、形成されるカーボンナノチューブを垂直配向にすることができるので、広範囲に整列したナノ構造を構築できるという利点がある。垂直配向のカーボンナノチューブは、その用途によっては性能や寿命を低下させる触媒金属が残存しているので、触媒金属を除去することにより、さらに性能や寿命を向上させる余地がある。   As a method for forming carbon nanotubes, there is a CVD method, that is, a method in which a catalyst metal such as an iron catalyst is applied to a substrate, a raw material gas is supplied, and carbon nanotubes are grown on the catalyst metal. According to the CVD method, since the formed carbon nanotubes can be vertically aligned, there is an advantage that nanostructures arranged in a wide range can be constructed. Vertically-aligned carbon nanotubes still have catalyst metal that lowers performance and life depending on the application. Therefore, there is room for further improvement in performance and life by removing the catalyst metal.

触媒金属の除去方法としては、触媒金属を硝酸など酸溶液に溶かすことが考えられるが、この除去方法だと、カーボンナノチューブの垂直配向を崩すだけでなく、カーボンナノチューブに損傷を与えて格子欠陥を生じさせることになる。このため、酸溶液を用いずに、カーボンナノチューブを加熱することで、残存する触媒金属を蒸発させて除去する方法が開示されている（例えば、特許文献１参照）。   As a method for removing the catalyst metal, it is conceivable to dissolve the catalyst metal in an acid solution such as nitric acid. However, this removal method not only destroys the vertical orientation of the carbon nanotubes, but also damages the carbon nanotubes to cause lattice defects. Will be generated. For this reason, a method of evaporating and removing the remaining catalytic metal by heating carbon nanotubes without using an acid solution has been disclosed (for example, see Patent Document 1).

特開２００５−３０６６８１号公報JP 2005-306681 A

しかしながら、上記特許文献１に記載の除去方法では、蒸発した触媒金属がカーボンナノチューブに再付着するという問題が考えられる。蒸発した触媒金属がカーボンナノチューブに再付着するのであれば、当然ながら、カーボンナノチューブから触媒金属を確実に除去することができず、高品質のカーボンナノチューブを得ることができない。   However, the removal method described in Patent Document 1 may have a problem that the evaporated catalyst metal reattaches to the carbon nanotubes. If the evaporated catalyst metal is reattached to the carbon nanotube, naturally, the catalyst metal cannot be reliably removed from the carbon nanotube, and high quality carbon nanotubes cannot be obtained.

そこで、本発明は、蒸発した触媒金属がカーボンナノチューブに再付着することを防止し、配向を崩すことなくカーボンナノチューブから確実に触媒金属を除去することで、高純度で高品質のカーボンナノチューブを得ることができる触媒金属の除去方法を提供することを目的とする。   Therefore, the present invention prevents the evaporated catalyst metal from reattaching to the carbon nanotubes, and reliably removes the catalyst metal from the carbon nanotubes without breaking the orientation, thereby obtaining high-purity and high-quality carbon nanotubes. It is an object of the present invention to provide a method for removing a catalytic metal.

上記課題を解決するため、本発明の請求項１に係る触媒金属の除去方法は、基板に触媒金属を介して形成させたカーボンナノチューブから、ナノ粒子である当該触媒金属を除去する触媒金属の除去方法であって、
上記基板の近傍に配置された上記触媒金属と同種の金属からなる金属材を、当該金属材の溶解温度未満である蒸着用温度で加熱し、
所定の真空度において、上記基板を上記触媒金属の蒸発温度以上である蒸発用温度で加熱することにより、当該触媒金属を蒸発させて上記金属材に蒸着させ、
上記蒸着用温度が、上記蒸発用温度よりも０〜１００℃低い温度であるものである。 In order to solve the above-mentioned problem, a method for removing a catalytic metal according to claim 1 of the present invention is a method for removing a catalytic metal that removes the catalytic metal as a nanoparticle from a carbon nanotube formed on a substrate via the catalytic metal. A method,
Heating a metal material made of the same kind of metal as the catalyst metal disposed in the vicinity of the substrate at a deposition temperature that is lower than the melting temperature of the metal material,
By heating the substrate at an evaporation temperature equal to or higher than the evaporation temperature of the catalyst metal at a predetermined degree of vacuum, the catalyst metal is evaporated and deposited on the metal material ,
The deposition temperature is 0 to 100 ° C. lower temperature der shall than the evaporating temperature.

また、本発明の請求項２に係る触媒金属の除去方法は、請求項１に記載の触媒金属の除去方法において、金属材が、蒸発した触媒金属を蒸着させ得る蒸着面を有し、
上記蒸着面が、鏡面加工されているものである。 Moreover, the method for removing a catalytic metal according to claim 2 of the present invention is the method for removing a catalytic metal according to claim 1, wherein the metal material has an evaporation surface on which evaporated catalyst metal can be evaporated,
The vapor deposition surface is mirror-finished.

さらに、本発明の請求項３に係る触媒金属の除去方法は、請求項２に記載の触媒金属の除去方法において、金属材の蒸着面と、基板のカーボンナノチューブが形成された面とが略平行であるものである。   Furthermore, the catalyst metal removal method according to claim 3 of the present invention is the catalyst metal removal method according to claim 2, wherein the vapor deposition surface of the metal material and the surface of the substrate on which the carbon nanotubes are formed are substantially parallel. It is what is.

また、本発明の請求項４に係る触媒金属の除去方法は、請求項１乃至３のいずれか一項に記載の触媒金属の除去方法において、触媒金属および金属材が、鉄、コバルトまたはニッケルからなるものである。 A catalyst metal removal method according to claim 4 of the present invention is the catalyst metal removal method according to any one of claims 1 to 3 , wherein the catalyst metal and the metal material are iron, cobalt, or nickel. It will be.

また、本発明の請求項５に係る触媒金属の除去方法は、請求項１乃至４のいずれか一項に記載の触媒金属の除去方法において、所定の真空度が、１０−５〜１０−２Ｐａであるものである。 The catalyst metal removal method according to claim 5 of the present invention is the catalyst metal removal method according to any one of claims 1 to 4 , wherein the predetermined degree of vacuum is 10 −5 to 10 −2. Pa.

上記触媒金属の除去方法によると、蒸発した触媒金属がカーボンナノチューブに再付着することを防止し、配向を崩すことなくカーボンナノチューブから確実に触媒金属を除去することで、高純度で高品質のカーボンナノチューブを得ることができる。   According to the above catalyst metal removal method, the catalyst metal that has evaporated is prevented from reattaching to the carbon nanotubes, and the catalyst metal is reliably removed from the carbon nanotubes without breaking the orientation. Nanotubes can be obtained.

本発明の実施の形態に係る触媒金属の除去方法において使用する装置の側部断面図である。It is side part sectional drawing of the apparatus used in the removal method of the catalyst metal which concerns on embodiment of this invention. 同装置の変形例を示す図であり、同装置がカーボンナノチューブ製造装置に組み込まれた状態を示す側部断面図である。It is a figure which shows the modification of the apparatus, and is a sectional side view which shows the state with which the apparatus was integrated in the carbon nanotube manufacturing apparatus.

以下、本発明の実施の形態に係る触媒金属の除去方法について、図面に基づき説明する。
本発明の実施の形態に係る触媒金属の除去方法は、基板に形成された垂直配向のカーボンナノチューブから、その垂直配向を維持しつつ、当該カーボンナノチューブに残存する触媒金属を確実に除去することで、高純度で高品質のカーボンナノチューブを得るものである。 Hereinafter, a method for removing a catalytic metal according to an embodiment of the present invention will be described with reference to the drawings.
The method for removing a catalytic metal according to an embodiment of the present invention is to reliably remove the catalytic metal remaining in the carbon nanotube from the vertically aligned carbon nanotube formed on the substrate while maintaining the vertical alignment. , To obtain high-purity and high-quality carbon nanotubes.

まず、上記垂直配向のカーボンナノチューブについて簡単に説明する。
このカーボンナノチューブは、例えば、熱ＣＶＤ法により形成されるものである。熱ＣＶＤ法では、基板に金属微粒子である触媒金属を塗布した後に、当該基板を加熱するとともにアセチレンガスなどの原料ガスを当該基板に供給することで、当該触媒金属上に垂直配向のカーボンナノチューブが形成される。このようなカーボンナノチューブには触媒金属が残存しており、当該触媒金属（金属微粒子）は個々の粒径がナノメートルオーダ（１〜１００ｎｍ）のナノ粒子である。また、上記カーボンナノチューブは、個々のチューブが互いに支え合っているため、触媒金属が除去されても垂直配向を維持し得る。ところで、上記触媒金属には、鉄、コバルトまたはニッケルが用いられる。また、基板Ｋは、後述するが触媒金属（金属微粒子）の蒸発温度以上に加熱されるので、この加熱に耐え得るシートまたは板材であればよく、例えば、ステンレス鋼板、石英ガラス、カーボンクロスシートなど、またはこれらの複合材が用いられる。 First, the vertically aligned carbon nanotube will be briefly described.
The carbon nanotube is formed by, for example, a thermal CVD method. In the thermal CVD method, after applying catalytic metal, which is metal fine particles, to the substrate, the substrate is heated and a source gas such as acetylene gas is supplied to the substrate, so that vertically aligned carbon nanotubes are formed on the catalytic metal. It is formed. The catalytic metal remains in such carbon nanotubes, and the catalytic metal (metal fine particles) is a nanoparticle having an individual particle size on the order of nanometers (1 to 100 nm). In addition, since the individual tubes of the carbon nanotubes support each other, the carbon nanotube can maintain the vertical orientation even if the catalytic metal is removed. By the way, iron, cobalt, or nickel is used as the catalyst metal. Further, since the substrate K is heated to a temperature higher than the evaporation temperature of the catalytic metal (metal fine particles), which will be described later, it may be any sheet or plate material that can withstand this heating. For example, stainless steel plate, quartz glass, carbon cloth sheet Or a composite of these.

以下、基板に形成されたカーボンナノチューブから、ナノ粒子である触媒金属を除去する装置および方法について説明する。
図１に示すように、触媒金属を除去する装置１は、基板Ｋを内部に配置するとともに加熱して当該基板Ｋに形成されたカーボンナノチューブＣから触媒金属を蒸発させて除去する除去室２と、この除去室２内の温度を制御する温度制御装置（図示しない）とを有している。上記除去室２は、その両側壁部にそれぞれ形成された基板Ｋ交換用の連通口３と、これら連通口３にそれぞれ配置された仕切弁４とを備えている。また、上記除去室２は、その内部に配置される基板Ｋを載置する水平支持台５と、この水平支持台５の下方に配置されて基板Ｋを下方から加熱する基板加熱用ヒータ６と、除去室２内の上壁部に設けられて基板Ｋの上方にバルク材７（金属材の一例である）を配置するバルク材保持具８と、図示しないがバルク材７の近傍に配置されて当該バルク材７を加熱するバルク材加熱用ヒータと、除去室２の内壁面に配置された断熱材９とを備えている。さらに、上記除去室２には、還元ガス（例えばＨ２ガスなど）をガス供給管１１により除去室２内に供給するガス供給部１２と、還元ガスとともに蒸発させた触媒金属を除去室２内からガス排出管２１により排出する真空ポンプ２２とが設けられている。ここで、上記バルク材７は、上記触媒金属と同種の金属（つまり、鉄、コバルトまたはニッケルである）からなる直方体であり、少なくとも底面が、カーボンナノチューブＣから蒸発させた触媒金属を蒸着させ得る蒸着面７Ｄとして鏡面加工されたものである。このバルク材７は、上面が上記バルク材保持具８で保持されるとともに、蒸着面７Ｄである底面が基板Ｋに対して平行に且つ間隔が１０〜２００ｍｍ程度となるようにして、除去室２内に配置される。蒸着面７Ｄに酸化膜が生成すると、バルク材７に触媒金属が蒸着するのを妨げることになるが、ガス供給管１１により除去室２内に還元ガス（例えばＨ２ガスなど）を供給することで、蒸着面７Ｄに酸化膜が生成するのを防ぐようにされている。また、上記真空ポンプ２２は、除去室２内の圧力を１０−５〜１０−２Ｐａ程度にし得る性能を有するものである。なぜなら、除去室２内の圧力が高ければ、蒸発した触媒金属（金属微粒子）は、その原子の平均自由行程が短くなり、バルク材７に到達する効率が低下するからである。ところで、除去室２内は基板加熱用ヒータ６およびバルク材加熱用ヒータにより高温となるため、除去室２内に配置される上記バルク材保持具８、水平支持台５、仕切弁４、ガス供給管１１およびガス排出管２１は、いずれも耐熱性を有する材料で構成されている。また、バルク材保持具８および仕切弁４は断熱性も必要であり、例えば炭素系材料や耐熱レンガなどで構成されている。 Hereinafter, an apparatus and method for removing the catalytic metal, which is a nanoparticle, from the carbon nanotubes formed on the substrate will be described.
As shown in FIG. 1, the apparatus 1 for removing the catalyst metal includes a removal chamber 2 in which the substrate K is disposed and heated to remove the catalyst metal from the carbon nanotubes C formed on the substrate K by evaporation. And a temperature control device (not shown) for controlling the temperature in the removal chamber 2. The removal chamber 2 includes a communication port 3 for exchanging substrates K formed on both side walls, and gate valves 4 respectively disposed in the communication ports 3. The removal chamber 2 includes a horizontal support 5 for placing the substrate K disposed therein, and a substrate heater 6 disposed below the horizontal support 5 for heating the substrate K from below. A bulk material holder 8 provided on the upper wall portion in the removal chamber 2 and disposing a bulk material 7 (an example of a metal material) above the substrate K; and not shown, but disposed in the vicinity of the bulk material 7. And a bulk material heating heater for heating the bulk material 7 and a heat insulating material 9 disposed on the inner wall surface of the removal chamber 2. Further, in the removal chamber 2, a gas supply unit 12 that supplies a reducing gas (for example, H 2 gas) into the removal chamber 2 through the gas supply pipe 11, and a catalytic metal evaporated together with the reducing gas are contained in the removal chamber 2. And a vacuum pump 22 for discharging the gas through a gas discharge pipe 21. Here, the bulk material 7 is a rectangular parallelepiped made of the same kind of metal as the catalyst metal (that is, iron, cobalt, or nickel), and at least the bottom surface can deposit the catalyst metal evaporated from the carbon nanotube C. The deposition surface 7D is mirror-finished. The bulk material 7 has its upper surface held by the bulk material holder 8 and the bottom surface, which is the vapor deposition surface 7D, is parallel to the substrate K and the interval is about 10 to 200 mm. Placed inside. When an oxide film is generated on the vapor deposition surface 7D, it prevents the catalytic metal from being vapor deposited on the bulk material 7, but a reducing gas (for example, H 2 gas) is supplied into the removal chamber 2 through the gas supply pipe 11. Thus, an oxide film is prevented from being formed on the vapor deposition surface 7D. Moreover, the said vacuum pump 22 has the performance which can make the pressure in the removal chamber 2 into about 10 < -5 > -10 <-2 > Pa. This is because, if the pressure in the removal chamber 2 is high, the evaporated catalyst metal (metal fine particles) has a shorter mean free path of its atoms and the efficiency of reaching the bulk material 7 is reduced. The removal chamber 2 is heated to a high temperature by the substrate heating heater 6 and the bulk material heating heater. Therefore, the bulk material holder 8, the horizontal support base 5, the gate valve 4, and the gas supply disposed in the removal chamber 2. Both the pipe 11 and the gas discharge pipe 21 are made of a material having heat resistance. Moreover, the bulk material holder 8 and the gate valve 4 also need to have heat insulation properties, and are made of, for example, a carbon-based material or a heat-resistant brick.

上記温度制御装置は、図示しないが、バルク材加熱用ヒータによる加熱温度を制御するバルク材温度制御部と、基板加熱用ヒータ６による加熱温度を制御する基板温度制御部とを備えている。上記バルク材温度制御部は、バルク材７を、当該バルク材７を構成する金属の溶解温度未満の温度（以下、蒸着用温度という）に加熱し得るようにされており、上記基板温度制御部は、基板Ｋを、触媒金属（金属微粒子）の蒸発温度以上で且つカーボンナノチューブＣの耐熱温度以下の温度（以下、蒸発用温度という）にし得るようにされている。なお、触媒金属の蒸発温度は、この触媒金属がナノ粒子であるから、バルク材７の蒸発温度より低いのは勿論のこと、バルク材７の溶解温度よりも低い。また、カーボンナノチューブＣの耐熱温度は、還元ガス下（酸化性物質が無い状態）だと高くなり、２０００℃以上である。ここで、蒸着用温度は、バルク材７を構成する金属の溶解温度を超えないものとして、蒸発用温度よりも０〜１００℃（好ましくは４０〜８０℃）低い温度で設定される。なぜなら、バルク材７の温度（蒸着用温度）が基板Ｋの温度（蒸発用温度）よりも遥かに低ければ、蒸発してバルク材７に蒸着した触媒金属が、バルク材７と一体化せずナノ粒子のままとなり、再び蒸発してカーボンナノチューブＣに再付着するからである。   Although not shown, the temperature control device includes a bulk material temperature control unit that controls the heating temperature by the bulk material heating heater and a substrate temperature control unit that controls the heating temperature by the substrate heating heater 6. The bulk material temperature control unit can heat the bulk material 7 to a temperature lower than the melting temperature of the metal constituting the bulk material 7 (hereinafter referred to as a deposition temperature), and the substrate temperature control unit The substrate K can be set to a temperature not lower than the evaporation temperature of the catalyst metal (metal fine particles) and not higher than the heat resistant temperature of the carbon nanotube C (hereinafter referred to as an evaporation temperature). The catalyst metal evaporation temperature is lower than the evaporation temperature of the bulk material 7 as well as the evaporation temperature of the bulk material 7 because the catalyst metal is nanoparticles. In addition, the heat resistant temperature of the carbon nanotube C is high under a reducing gas (in the absence of an oxidizing substance) and is 2000 ° C. or higher. Here, the temperature for vapor deposition is set at a temperature 0 to 100 ° C. (preferably 40 to 80 ° C.) lower than the temperature for evaporation, assuming that it does not exceed the melting temperature of the metal constituting the bulk material 7. This is because if the temperature of the bulk material 7 (temperature for vapor deposition) is much lower than the temperature of the substrate K (temperature for evaporation), the catalyst metal evaporated and deposited on the bulk material 7 will not be integrated with the bulk material 7. This is because the nanoparticles remain as they are, and are evaporated again to reattach to the carbon nanotubes C.

次に、上述した装置１を用いて触媒金属を除去する方法について説明する。
予め、バルク材７を、底面が水平支持台５に対して平行となるようにして、バルク材保持具８で除去室２内に配置しておく。そして、仕切弁４を開にして、基板Ｋを連通口３から除去室２内に入れ、カーボンナノチューブＣが形成された面を上にして基板Ｋを水平支持台５に載置し、仕切弁４を閉にする。 Next, a method for removing the catalytic metal using the above-described apparatus 1 will be described.
The bulk material 7 is previously placed in the removal chamber 2 with the bulk material holder 8 so that the bottom surface is parallel to the horizontal support 5. Then, the gate valve 4 is opened, the substrate K is put into the removal chamber 2 through the communication port 3, the substrate K is placed on the horizontal support 5 with the surface on which the carbon nanotubes C are formed facing upward, 4 is closed.

その後、ガス供給部１２により除去室２内に還元ガスを供給するとともに、真空ポンプ２２により除去室２内から還元ガスを排出して、除去室２内の圧力を１０−５〜１０−２Ｐａ程度にしておく。 Thereafter, the reducing gas is supplied into the removal chamber 2 by the gas supply unit 12, and the reducing gas is discharged from the removal chamber 2 by the vacuum pump 22 so that the pressure in the removal chamber 2 is 10 −5 to 10 −2 Pa. Keep it at a degree.

そして、温度制御装置により、バルク材７が蒸着用温度、基板Ｋが蒸発用温度となるように加熱する。基板Ｋの加熱時間は、蒸発用温度にもよるが、触媒金属が確実に蒸発して除去されるためにも、１〜１０時間程度である。   Then, the temperature control device heats the bulk material 7 so that the deposition temperature and the substrate K become the evaporation temperature. Although the heating time of the substrate K depends on the evaporation temperature, it is about 1 to 10 hours in order to surely remove the catalyst metal by evaporation.

基板Ｋが蒸発用温度に達すると、この基板Ｋに形成されたカーボンナノチューブＣから触媒金属が蒸発する。なお、蒸発用温度はカーボンナノチューブＣの耐熱温度以下であるから、基板Ｋが蒸発用温度に達しても、カーボンナノチューブＣは損傷しない。   When the substrate K reaches the evaporation temperature, the catalytic metal evaporates from the carbon nanotubes C formed on the substrate K. Since the evaporation temperature is lower than the heat resistant temperature of the carbon nanotube C, the carbon nanotube C is not damaged even when the substrate K reaches the evaporation temperature.

カーボンナノチューブＣから蒸発した触媒金属のうち、一部は真空ポンプ２２により除去室２から排出され、残りはバルク材７の蒸着面７Ｄに蒸着する（図１の破線矢印参照）。バルク材７は、蒸着用温度（蒸発用温度より０〜１００℃低い温度）であるとともに、触媒金属と同種の金属からなるので、バルク材７に蒸着した触媒金属は、バルク材７と一体化する。また、除去室２内に還元ガスが供給されているので、蒸着を妨げる酸化膜が蒸着面７Ｄに生成しない。さらに、蒸着面７Ｄが鏡面加工されているので、蒸着面７Ｄに蒸着した触媒金属は、よりバルク材７と一体化しやすくなり、再び蒸発しない。   A part of the catalyst metal evaporated from the carbon nanotube C is discharged from the removal chamber 2 by the vacuum pump 22, and the rest is deposited on the deposition surface 7D of the bulk material 7 (see the broken line arrow in FIG. 1). Since the bulk material 7 has a vapor deposition temperature (a temperature lower by 0 to 100 ° C. than the evaporation temperature) and is made of the same kind of metal as the catalyst metal, the catalyst metal deposited on the bulk material 7 is integrated with the bulk material 7. To do. Further, since the reducing gas is supplied into the removal chamber 2, an oxide film that hinders vapor deposition is not generated on the vapor deposition surface 7D. Furthermore, since the vapor deposition surface 7D is mirror-finished, the catalyst metal deposited on the vapor deposition surface 7D is more easily integrated with the bulk material 7, and does not evaporate again.

カーボンナノチューブＣから触媒金属が十分に除去されると、温度制御装置により除去室２内を常温に戻し、仕切弁４を開にして基板Ｋを取り出す。
以下、上記実施の形態をより具体的に示した実施例に係る触媒金属の除去方法について説明する。 When the catalytic metal is sufficiently removed from the carbon nanotubes C, the inside of the removal chamber 2 is returned to room temperature by the temperature control device, the gate valve 4 is opened, and the substrate K is taken out.
Hereinafter, a method for removing a catalyst metal according to an example showing the above embodiment more specifically will be described.

カーボンナノチューブＣを形成した熱ＣＶＤ法では、触媒金属として鉄触媒を用いた。したがって、触媒金属を除去する装置１には、バルク材７として、鉄触媒と同種の金属である鉄からなるものを用いた。ここで、鉄のナノ粒子の蒸発温度は１１００℃程度で且つカーボンナノチューブＣの耐熱温度は上述の通り２０００℃以上であるから、蒸発用温度を１１００〜２０００℃程度の任意の温度にした。また、鉄の融点（当然ながら、溶解温度は融点以下である）は１５３５℃であるから、蒸発用温度が１５００℃未満であれば蒸着用温度を蒸発用温度と同一または少し低温とし、蒸発用温度が１５００℃以上であれば蒸着用温度を１５００℃以下の温度で一定にした。さらに、除去室２内を１０−５〜１０−２Ｐａの任意の圧力にし、基板Ｋの加熱時間を鉄触媒が確実に除去される時間（１〜１０時間の任意の時間）とした。また、還元ガスとしてＨ２ガスを用いた。 In the thermal CVD method in which the carbon nanotube C was formed, an iron catalyst was used as the catalyst metal. Therefore, for the apparatus 1 for removing the catalyst metal, the bulk material 7 is made of iron which is the same kind of metal as the iron catalyst. Here, the evaporation temperature of the iron nanoparticles is about 1100 ° C., and the heat-resistant temperature of the carbon nanotube C is 2000 ° C. or more as described above. Therefore, the evaporation temperature is set to an arbitrary temperature of about 1100 to 2000 ° C. Further, since the melting point of iron (of course, the melting temperature is not higher than the melting point) is 1535 ° C., if the evaporation temperature is less than 1500 ° C., the vapor deposition temperature is set equal to or slightly lower than the evaporation temperature. If temperature was 1500 degreeC or more, the temperature for vapor deposition was made constant at the temperature of 1500 degrees C or less. Furthermore, the inside of the removal chamber 2 was set to an arbitrary pressure of 10 −5 to 10 −2 Pa, and the heating time of the substrate K was set to a time for reliably removing the iron catalyst (an arbitrary time of 1 to 10 hours). Further, H 2 gas was used as the reducing gas.

このような条件下で、カーボンナノチューブＣから鉄触媒を確実に除去して、高純度で高品質のカーボンナノチューブＣを得ることができた。
このように、上述した実施の形態および実施例に係る触媒金属の除去方法によると、垂直配向のカーボンナノチューブＣから、触媒金属を蒸発させてバルク鉄に蒸着させるので、カーボンナノチューブＣの垂直配向を維持したまま、触媒金属を除去することができる。 Under such conditions, the iron catalyst was surely removed from the carbon nanotubes C, and high-purity and high-quality carbon nanotubes C could be obtained.
As described above, according to the catalyst metal removal method according to the above-described embodiment and examples, the catalyst metal is evaporated from the vertically aligned carbon nanotubes C and deposited on the bulk iron. While maintained, the catalytic metal can be removed.

また、バルク材７が、触媒金属と同種の金属からなるとともに、蒸着した触媒金属がバルク材７と一体化する温度（蒸着用温度）に設定されているので、蒸着した触媒金属がバルク材７と一体化することで、当該触媒金属が再蒸発してカーボンナノチューブＣに再付着することを防止し、確実に触媒金属を除去することができる。   Further, since the bulk material 7 is made of the same kind of metal as the catalyst metal and is set to a temperature at which the deposited catalyst metal is integrated with the bulk material 7 (deposition temperature), the deposited catalyst metal is the bulk material 7. , It is possible to prevent the catalyst metal from re-evaporating and reattaching to the carbon nanotubes C, and to remove the catalyst metal reliably.

さらに、蒸着面７Ｄが基板Ｋと平行に配置されるとともに、蒸着を妨げる酸化膜が蒸着面７Ｄに生成しないので、蒸発した触媒金属が蒸着面７Ｄに蒸着しやすく、また蒸着面７Ｄが鏡面加工されているので、蒸着した触媒金属がよりバルク材７と一体化しやすくなり、したがって、より確実に触媒金属を除去することができる。   Furthermore, since the vapor deposition surface 7D is arranged in parallel with the substrate K and an oxide film that prevents vapor deposition is not generated on the vapor deposition surface 7D, the evaporated catalyst metal is easily deposited on the vapor deposition surface 7D, and the vapor deposition surface 7D is mirror-finished. Therefore, the deposited catalyst metal can be more easily integrated with the bulk material 7, and therefore the catalyst metal can be more reliably removed.

また、カーボンナノチューブＣの垂直配向を維持したまま、より確実に触媒金属が除去されることで、高純度で高品質のカーボンナノチューブを得ることができる。
ところで、上記実施の形態および実施例では、還元ガスの例としてＨ２ガスについて説明したが、これに限定されるものではなく、バルク材７の蒸着面７Ｄに酸化膜が生成するのを防ぐものであれば、ＣＯガスなど他の還元ガスであってもよい。 Further, the catalytic metal is more reliably removed while maintaining the vertical alignment of the carbon nanotubes C, whereby high-purity and high-quality carbon nanotubes can be obtained.
However, those in the foregoing embodiment and the foregoing examples have been described H 2 gas as an example of the reducing gas, which is not limited to this, the oxide film on the deposition surface 7D of the bulk material 7 is prevented from generating Any other reducing gas such as CO gas may be used.

また、上記実施の形態では、触媒金属およびバルク材が、鉄、コバルトまたはニッケルからなるとして説明したが、鉄、コバルトおよび／またはニッケルを含む合金からなるものであってもよい。   Moreover, in the said embodiment, although the catalyst metal and the bulk material demonstrated as consisting of iron, cobalt, or nickel, you may consist of an alloy containing iron, cobalt, and / or nickel.

ところで、上記実施の形態および実施例で説明した触媒金属を除去する装置１は、バッチ式の装置１として説明したが、図２に示すように、カーボンナノチューブ製造装置の一部に組み込まれた装置１’であってもよい。すなわち、この装置１’は、カーボンナノチューブ供給室４０の下流側で且つカーボンナノチューブ冷却室５０の上流側に隣接して配置されたものである。また、上記装置１’は、除去室２内から仕切弁４が撤去され、水平支持台５の代わりに上流側から下流側に基板Ｋを搬送するカーボンファイバークロスコンベア３１が設けられ、このカーボンファイバークロスコンベア３１を回動させるカーボンローラ３２が当該カーボンファイバークロスコンベア３１の下面に接して配置されたものである。この装置１’によると、高純度で高品質のカーボンナノチューブを連続して得ることができる。また、図２に示す基板ＫおよびカーボンナノチューブＣは、分断されたものであるが、連続的な帯状のものであってもよい。   By the way, although the apparatus 1 for removing the catalyst metal described in the above embodiment and examples has been described as a batch type apparatus 1, as shown in FIG. 2, an apparatus incorporated in a part of the carbon nanotube production apparatus. 1 'may be sufficient. In other words, this apparatus 1 ′ is disposed downstream of the carbon nanotube supply chamber 40 and adjacent to the upstream side of the carbon nanotube cooling chamber 50. Further, the apparatus 1 ′ is provided with a carbon fiber cross conveyor 31 in which the gate valve 4 is removed from the removal chamber 2 and the substrate K is transported from the upstream side to the downstream side instead of the horizontal support 5. A carbon roller 32 for rotating the cross conveyor 31 is disposed in contact with the lower surface of the carbon fiber cross conveyor 31. According to this apparatus 1 ', high-purity and high-quality carbon nanotubes can be obtained continuously. Moreover, although the board | substrate K and the carbon nanotube C which are shown in FIG. 2 are parted, a continuous strip | belt shape may be sufficient.

Ｋ 基板
Ｃ カーボンナノチューブ
１ 装置
２ 除去室
３ 連通口
４ 仕切弁
５ 水平支持台
６ 基板加熱用ヒータ
７ バルク材
８ バルク材保持具
９ 断熱材
１１ ガス供給管
１２ ガス供給部
２１ ガス排出管
２２ 真空ポンプ
３１ カーボンファイバークロスコンベア
３２ カーボンローラ
４０ カーボンナノチューブ供給室
５０ カーボンナノチューブ冷却室 K substrate C carbon nanotube 1 device 2 removal chamber 3 communication port 4 gate valve 5 horizontal support stand 6 heater for substrate 7 bulk material 8 bulk material holder 9 heat insulating material 11 gas supply pipe 12 gas supply pipe 21 gas discharge pipe 22 vacuum Pump 31 Carbon fiber cross conveyor 32 Carbon roller 40 Carbon nanotube supply chamber 50 Carbon nanotube cooling chamber

Claims (5)

基板に触媒金属を介して形成させたカーボンナノチューブから、ナノ粒子である当該触媒金属を除去する触媒金属の除去方法であって、
上記基板の近傍に配置された上記触媒金属と同種の金属からなる金属材を、当該金属材の溶解温度未満である蒸着用温度で加熱し、
所定の真空度において、上記金属材に還元ガスを供給し、上記基板を上記触媒金属の蒸発温度以上である蒸発用温度で加熱することにより、当該触媒金属を蒸発させて上記金属材に蒸着させ、
上記蒸着用温度が、上記蒸発用温度よりも０〜１００℃低い温度であることを特徴とする触媒金属の除去方法。 A catalyst metal removal method for removing the catalyst metal, which is a nanoparticle, from a carbon nanotube formed on the substrate via the catalyst metal,
Heating a metal material made of the same kind of metal as the catalyst metal disposed in the vicinity of the substrate at a deposition temperature that is lower than the melting temperature of the metal material,
By supplying a reducing gas to the metal material at a predetermined degree of vacuum and heating the substrate at an evaporation temperature that is equal to or higher than the evaporation temperature of the catalyst metal, the catalyst metal is evaporated and deposited on the metal material. ,
The deposition temperature, method for removing the catalyst metal, wherein 0 to 100 ° C. lower temperature der Rukoto than the evaporating temperature. 金属材が、蒸発した触媒金属を蒸着させ得る蒸着面を有し、
上記蒸着面が、鏡面加工されていることを特徴とする請求項１に記載の触媒金属の除去方法。 The metal material has a deposition surface on which the evaporated catalyst metal can be deposited;
2. The method for removing a catalytic metal according to claim 1, wherein the vapor deposition surface is mirror-finished. 金属材の蒸着面と、基板のカーボンナノチューブが形成された面とが略平行であることを特徴とする請求項２に記載の触媒金属の除去方法。   The method for removing a catalytic metal according to claim 2, wherein the vapor deposition surface of the metal material and the surface of the substrate on which the carbon nanotubes are formed are substantially parallel. 触媒金属および金属材が、鉄、コバルトまたはニッケルからなることを特徴とする請求項１乃至３のいずれか一項に記載の触媒金属の除去方法。 The method for removing a catalyst metal according to any one of claims 1 to 3, wherein the catalyst metal and the metal material are iron, cobalt, or nickel . 所定の真空度が、１０ −５ 〜１０ −２ Ｐａであることを特徴とする請求項１乃至４のいずれか一項に記載の触媒金属の除去方法。 The method for removing a catalytic metal according to claim 1 , wherein the predetermined degree of vacuum is 10 −5 to 10 −2 Pa .
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