JP3402032B2 - Carbon tube containing foreign substance and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon tube, and more particularly, it relates to a carbon tube having a specific shape containing a foreign substance, which cannot be conventionally manufactured, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Heretofore, fine carbon tubes have been manufactured by arc discharge of a graphite electrode, vapor phase pyrolysis, etc., and are expected to have various applications due to their special shapes. As is clear from the manufacturing method, only such a carbon tube having a very small size such as a diameter could be manufactured. Further, a carbon tube containing a foreign substance is also obtained by using a carbon tube obtained by a similar manufacturing method and containing lead and the like, but similarly, only a small size can be manufactured. Further, in order to manufacture a carbon tube having a large diameter, flame-resistant polyacrylonitrile (hereinafter referred to as “PAN”)
Abbreviated. ) Type carbon fiber is heat-treated to make a hollow carbon tube (“Carbon” 1992 15
No. 5, page 307, etc.), but in this case, inclusion of foreign substances has not been reported.

[0003]

However, due to the manufacturing method, it is difficult to obtain a carbon tube having a uniform diameter, and it is difficult to increase the diameter of the tube. Since both ends were obtained in a closed form, it was necessary to insert a foreign substance after forming a carbon tube with both ends or one end open by oxidation treatment or the like. Further, in the method of heat-treating the flame-resistant PAN-based carbon fiber, since the diameter of the PAN-based carbon fiber itself is in the order of micron, it is possible to obtain only the carbon tube having the diameter in the order of micron. The obtained carbon tube only had a knot, and as a result, it was difficult to encapsulate a foreign substance in the entire carbon tube.

[0004]

As a result of intensive studies, the inventors of the present invention have found that a carbon tube having a uniform diameter can be obtained by using an inorganic substance having substantially linear pores as if it were a formwork. Manufacture, and then insert the foreign substance into the carbon tube to encapsulate the foreign substance and
It is possible to manufacture a carbon tube that does not have foreign substances attached to the outside of the carbon tube.
The present invention has been accomplished by finding that it is possible to obtain a carbon tube having no foreign substance attached to the outside . That is, the object of the present invention is to enclose a foreign substance of a size that has not been obtained hitherto , and to keep the foreign substance on the outside of the carbon tube.
And by providing a carbon tubes unattached, also other objectives uniform size of the present invention, by encapsulating foreign substances and foreign substances are attached to the outside of the carbon tube
Not to provide a method of mass producing carbon tubes.

The object of the present invention is to obtain a diameter of 10
nm to 1 μm, length of 1 to 100 μm, a foreign substance is contained in a carbon tube, and the outside of the carbon tube
A carbon tube with no foreign substances attached to it , an organic substance is coated on the inner wall of the pores of an inorganic substance having substantially linear pores,
The organic compound is carbonized by heating it, or gaseous hydrocarbons are vapor-phase carbonized in the pores, a carbon thin film is deposited on the inner walls of the pores, and foreign substances are further contained in the pores. after allowed inserted, the inorganic substance dissolved and removed, impurities are contained, and foreign substances on the outside of the carbon tube
It is achieved by a method of manufacturing a carbon tube in which is not attached .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The present invention relates to Japanese Patent Application No. 6-31
This is a carbon tube shown in No. 4066 in which a foreign substance is included. That is, diameter 10 nm to 1 μ
m, a foreign substance is contained in a carbon tube having a length of 1 to 100 μm , and the foreign substance is attached to the outside of the carbon tube.
The carbon tube not attached is usually coated with an organic substance on the inner wall of the pores of an inorganic substance having substantially linear pores, and carbonizes the organic substance by heating it, or in the pores, Gaseous hydrocarbon is vapor-phase carbonized and a carbon thin film is deposited on the inner walls of the pores to form a precursor of a carbon tube as a matrix. Then, by inserting a foreign substance into the pores before dissolving and removing the inorganic substance,
Easy to manufacture. The state of the insertion substance may be changed by post-treatment.

A step of dissolving and removing an inorganic substance to be a mold;
The order of the step of inserting a foreign substance into the pores and the post-treatment performed for changing the state of the inserted substance are appropriately determined depending on the target inclusions and the content of the post-treatment.
For example, when the inclusions are changed by post-treatment, depending on the treatment conditions, if the inorganic substance of the mold reacts with the carbon of the carbon tube, or if the inclusions react, the inorganic substance to be the mold is dissolved and removed in advance. After that, post-treatment is performed to change the state of the inclusion. (Insert → Remove →
Post-treatment) Conversely, if the inclusion can be changed to a state in which it does not react with the dissolution liquid by post-treatment, a foreign substance is inserted into the pores and post-treatment is performed to make it not react with the dissolution liquid. After changing to, the inorganic material of the mold is dissolved and removed.
(Insertion → Post-treatment → Removal) In addition, if the step of dissolving and removing the inorganic substance is after the step of inserting a different substance regardless of the presence or absence of the post-treatment, a dissolution liquid for dissolving the inclusions and the inorganic substance. When the above reacts and dissolves, it is necessary to coat the pore openings with a substance that does not react with the solution. For example, carbon is coated by vapor deposition or vapor-phase carbonization to prevent the inclusions from dissolving.

[0008] As post processing is appropriately performed by the final inclusions of interest. For example, when it is difficult to obtain a metal in a liquid state when it is desired to obtain the final inclusion in a metal state, first insert it in the state of a metal compound such as a metal salt, and then perform a reduction treatment. By doing so, the metal state is changed. Further, when the final inclusion is desired to be a metal carbide or a carbon solid solution, the inserted metal compound or metal reacts with the surrounding carbon, or carbon is dissolved in the metal to cause the carbide or Heat treatment is performed at a predetermined temperature, for example, in a non-oxidizing atmosphere so that it becomes a solid solution of carbon.

Suitable inorganic substances having substantially linear pores used in the production method include anodic oxide coatings of various metals, zeolite (preferably type L), and clay minerals such as sepiolite. To be Of these, particularly preferred is an anodized film of aluminum (alumite).
Is. The diameter of the pores of the alumite may be controlled according to a conventional method. For example, the higher the voltage (high current density), the larger the diameter of the pores. The electrolytic solution used may be either acidic or alkaline. As the acidic electrolyte, sulfuric acid, oxalic acid, chromic acid, phosphoric acid, etc. are mainly used, and the diameter of the pores increases in this order.

As a method of forming carbon on the inner wall of the pore of the above-mentioned inorganic substance, a method of coating the inner wall of the pore with an organic substance and then carbonizing it by heating, or a method of vapor-phase carbonizing a gaseous hydrocarbon to form an inner wall of the pore A method of depositing a carbon thin film can be used. The organic substance used in the former method needs to be liquefied by some method, and examples of the liquefaction method include raising the temperature and dissolving it in a solvent. Specific examples of organic substances that can be used include furfuryl alcohol, polyvinyl alcohol, polyacrylonitrile, vinyl acetate, partially polymerized products thereof, pitches of coal and petroleum, and acenaphthylene.

The organic substance is brought into contact with the above-mentioned inorganic substance, the pores in the inorganic substance are filled, the organic substance is carbonized by heating this, and the inorganic substance is dissolved to form a carbon tube of a uniform size. It can be easily obtained in large quantities. When filling the pores in the inorganic substance with the organic substance,
It is preferable to reduce the pressure in advance because organic substances easily enter the pores.

The heating temperature for carbonizing the organic matter may be selected within a range such that carbonization of the organic matter occurs but the inorganic substance itself is not destroyed or reacts with the carbon tube itself to be produced, For example, in the case of alumite, 500 to 1300 ° C is preferable, and in the case of zeolite and sepiolite, 500 to 1000 ° C is preferable. If the temperature is lower than this range, the carbonization does not proceed easily.

On the other hand, in the method of gas-phase carbonizing a gaseous hydrocarbon, the form of the inorganic substance used in this case is a plate-like or thin-film-like one, and the linear pores are substantially linear. It is preferable that the pores are continuous in the thickness direction and both ends of the pores are open to the outside, because gaseous hydrocarbons can easily pass through the pores. For example, "A
"Nodisc" (manufactured by Whatman Paper Co., aluminum anodized film) and the like.

As the gaseous hydrocarbon used, a gaseous hydrocarbon such as methane, ethane, propane, propylene, benzene and ethylene at room temperature is preferably used. Such a gaseous hydrocarbon is usually circulated so as to come into contact with the inorganic substance together with the carrier gas. The flow rate at this time is not particularly limited because it varies depending on the length of the pores (thickness of the thin film) and the diameter of the pores. However, when the concentration of gaseous hydrocarbons is high or the residence time is long, the carbon tube is Since it may not be obtained, the gaseous hydrocarbon flow conditions are adjusted appropriately.

As a method for inserting a foreign substance into the carbon tube obtained as described above, it is made into a liquid state by some method, for example, in the case of a substance soluble in a solvent, in a solution state, , Carbon tube (or
When the inorganic substance coexisting as the mold is melted at a temperature at which it does not denature, it is brought into contact with the carbon tube in a molten state and inserted into the pores of the carbon tube. Specific examples of the former include metal salts such as sulfates, nitrates and chlorides, which are appropriately selected depending on the type of salt used such as an aqueous solution or an organic solvent solution. In this case, when the above-mentioned insertion substance is inserted into the carbon tube, it is preferable to reduce the pressure in advance because it is easy to enter the carbon tube. Specific examples of the latter include metallic substances such as lead and antimony that melt at relatively low temperatures. In this case, in order to improve the contact with the carbon tube, a metal substance to be inserted in advance is deposited on the carbon tube by vapor deposition, sputtering, etc., and then the temperature is raised to above the melting point to cause capillary action in the pores. And the like, or by contacting with the melt in a state where the pressure is reduced in advance and inserting into the pores.

As another method for inserting a foreign substance into the pores, if it is a substance which becomes gaseous by heat or the like, CVD
It can also be inserted by law. For example, a method in which a carbonyl complex of each metal or metallocene is used and these are introduced into the pores can be used. Such a foreign substance of the present invention is included, and the foreign substance is present outside the carbon tube.
The carbon tube which is not attached usually has an aspect ratio of 20 to 10,000.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the examples as long as the gist thereof is not exceeded. (Example 1) As an inorganic substance having substantially linear pores,
An aluminum anodic oxide film was used. This anodized film was produced as follows using the apparatus shown in FIG. First, the aluminum plate (5) to be anodized is arranged so that one side thereof contacts the electrolytic solution (20% sulfuric acid aqueous solution) (6) and the back side thereof contacts the ion-exchanged water (9). 8) was used. With such a configuration, a DC constant voltage of 20 V is applied for 2 hours to perform anodic oxidation, and then
The voltage of the anode and the cathode was reversed, and the voltage was applied for 10 minutes so that the constant current was 0.3 A, and the anodic oxide film was peeled off. The diameter of the pores in the obtained anodized film is about 30n
It was m.

In order to deposit a carbon thin film in the anodized film thus obtained, as shown in FIG. 3, one piece of this anodized film (1), a quartz reaction tube (2) having an inner diameter of 2 cm. It was placed on the glass fiber aggregate (3) inside, and the quartz tube was placed in the furnace, and the temperature was set to 800 ° C. by the heater (4). Next, in the above reaction tube, the propylene concentration was 2.5% by volume.
Gas mixed with nitrogen so that 200ml / min
Gas phase carbonization was performed for 3 hours at (STP).

Thereafter, four samples (200 mg) obtained in the same manner were treated with chloroplatinic acid (H ₂ PtCl ₆ .6H).
₂ O) in ethanol (10 g of H ₂ PtCl ₆・ 6H ₂ O
Approximately 40 cc of ethanol / liter of ethanol) is dropped onto the sample under vacuum, then left standing for 3 hours, and then dried by a drier 80
C. and dried under a nitrogen stream for 1 day. Then as post-processing,
This dried sample was put into a quartz reaction tube (inner diameter 2 cm) and heated at 500 ° C. under a hydrogen stream (H ₂ : 50 cc / min, N.
_2: 50cc / min) 3 hours to at and reduced chloroplatinic acid to platinum metal.

After this, 46% hydrofluoric acid aqueous solution 50
It was put in cc and stirred for 12 hours to dissolve the aluminum anodic oxide film, followed by filtration, washing and drying to obtain a carbon tube containing platinum metal. 1 and 2 are TEM photographs of the carbon tube containing platinum.
(Enlarged view). (Example 2) Under the same conditions as in Example 1, a sample in which a carbon thin film was deposited in the pores of an anodized film by vapor-phase carbonization was used, and as a substance to be encapsulated, an aqueous solution of iron chloride (50 g /
It was impregnated in 20 cc of liter) and left as it was for 3 hours. As a post-treatment, a sample dried at 80 ° C. under a nitrogen stream for 1 day was put into a quartz reaction tube (inner diameter 2 cm), and 700
℃, under hydrogen flow (H ₂ : 50cc / min, N ₂ : 50cc
/ Min) for 3 hours to reduce iron chloride to a metallic state.

Then, the sample is placed in a vacuum chamber, carbon sputtering is carried out, the pore openings of the sample are coated with carbon, and then the sample is placed in 50 cc of 46% hydrofluoric acid aqueous solution and stirred for 12 hours to obtain an aluminum anode. The oxide film was dissolved, filtered, washed, and dried to obtain a carbon tube containing iron in a metallic state.

[0022]

EFFECTS OF THE INVENTION According to the present invention, a foreign substance having a size which has not been obtained in the past can be contained and the carbon tube can be provided outside.
Providing a carbon tube with no foreign substances adhering to it , and encapsulating foreign substances of uniform size , and
It is possible to provide a method for mass-producing carbon tubes in which foreign substances are not attached to the outside of the tube. Then, such foreign substances are included , and foreign matter is present on the outside of the carbon tube.
Carbon tubes with no adherence are new composite materials, electrically conductive materials, quantum wire devices, ultra-high speed electrical devices,
It can be used as an ultra high density magnetic recording medium, a carbon film, a non-linear optical material and the like.

[Brief description of drawings]

FIG. 1 is a micrograph (TEM photograph) showing the fiber shape of a carbon tube containing platinum, which was obtained in Example 1.

FIG. 2 is a micrograph (TEM showing an enlarged view of the fiber shape of the carbon tube containing platinum, obtained in Example 1.
(Photo).

3 is an explanatory diagram of a carbon tube manufacturing apparatus used in Example 1. FIG.

FIG. 4 is an explanatory view of an apparatus for producing an anodized film of aluminum used in Example 1.

[Explanation of symbols]

1 Anodized film 2 Quartz tube 3 Glass fiber aggregate 4 heater 5 anode 6 Electrolyte (20% sulfuric acid aqueous solution) 7 cathode 8 aluminum plate 9 ion-exchanged water

Continuation of the front page (56) References JP-A-6-227806 (JP, A) Tateo, et al., Preparation of ultrafine carbon tubes using aluminum anodized skin as a template, Journal of Aluminum Research, July 1995. 10, p. 293, p. 55 C. Tsang, et. al, A Simple Chemical Methods of Opening and Filling Carbon Nanotubes, NATURE, November 10, 1994, vol. 372, p. 159-162 (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 31/02 101 D01F 9/127 JISST file (JOIS)

Claims (3)

(57) [Claims] 1. A diameter of 10 nm to 1 μm and a length of 1 to 100 μm
The foreign material was contained m the carbon tube of, and the car
A carbon tube characterized by no foreign substances adhering to the outside of the bon tube . 2. An organic substance is coated on the inner wall of an inorganic substance having substantially linear pores, and the organic compound is carbonized by heating it, or a carbonized gas is present in the pores. Hydrogen is vapor-phase carbonized, a carbon thin film is deposited on the inner walls of the pores, and then a foreign substance is inserted into the pores, and then the inorganic substance is dissolved and removed. And foreign substances adhere to the outside of the carbon tube.
Not a carbon tube manufacturing method. 3. A carbon tube containing a foreign substance according to claim 2, wherein the inorganic substance having substantially linear pores is any one of a metal anodic oxide coating, zeolite, and sepiolite. Foreign substances are attached to the outside of
No carbon tube manufacturing method.