JP2003292311A - Method for producing amorphous nanoscale carbon tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inexpensively and, industrially producing an amorphous nanoscale carbon tube in a high purity, high yield and high mass- productivity. <P>SOLUTION: This production method for the amorphous nanoscale carbon tube comprises heating a specific halogen-containing or chalcogen-containing resin in the presence of a catalyst comprising a metal powder and/or a metal salt. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an amorphous nanoscale carbon tube having carbon as a main skeleton and a hollow fiber shape having an outer diameter of 1 to 1000 nm.

[0002]

2. Description of the Related Art An amorphous nanoscale carbon tube is a tube-shaped nanoscale carbon material having an amorphous structure, unlike carbon nanotubes having a graphite structure which are conventionally known. Amorphous nanoscale carbon tubes are useful as a gas storage material, and their excellent gas storage capacity has attracted attention in the art.

In order to use it as a gas storage material, it is naturally necessary to synthesize a large amount of amorphous nanoscale carbon tubes at low cost.

Conventionally, as a method for producing an amorphous nanoscale carbon tube, polytetrafluoroethylene is used in the presence of a catalyst composed of metal powder and / or metal salt.
A method is known in which a thermally decomposable resin having a decomposition temperature of (PTFE) or the like of 200 to 900 ° C. is subjected to an excitation treatment by heating or the like (International Publication WO00 / 40509 relating to the application of the present applicant).

[0005]

The above method is an epoch-making manufacturing method capable of manufacturing an amorphous nanoscale carbon tube which has never been obtained. However, when PTFE or the like is used as the raw material pyrolyzable resin, the yield of amorphous nanoscale carbon tubes is high, but
However, it has the disadvantage of being expensive and not always easy to obtain. On the other hand, if a relatively inexpensive and easily available resin as a raw material, for example, a resin such as polyethylene is used, it is advantageous in cost reduction in terms of raw material, but the yield of the amorphous nanoscale carbon tube is not always satisfactory. There was a problem of not having.

Therefore, an object of the present invention is to provide a manufacturing method capable of manufacturing an amorphous nanoscale carbon tube in a large amount and at a low cost.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, at least one heat selected from the group consisting of specific readily available chlorine-based resins and chalcogen-containing resins. By using a degradable resin, we have found a production method that can produce a nanoscale carbon tube having a linear and stable amorphous structure of the nanoscale order with high purity and high yield, with high mass productivity and at low cost. .

The present invention has been completed on the basis of the above findings by further studies, and provides the following method for producing an amorphous nanoscale carbon tube.

Item 1 (A) At least one halogen-containing resin selected from the group consisting of polyvinyl chloride, chlorinated polyethylene and polyhexafluoropropylene, or
(B) (a) General formula (1)

[0010]

[Chemical 5]

[Wherein R ¹ is a phenylene group or a carbon number of 1
-10 shows an alkylene group, and X shows an oxygen atom or a sulfur atom. ] A resin comprising a structural unit represented by the formula (b), a general formula (2)

[0012]

[Chemical 6]

[In the formula, R ² is a hydrogen atom and has 1 to 2 carbon atoms.
0 represents an alkyl group, a phenyl group or a substituted phenyl group. ] At least one type of chalcogen-containing resin selected from the group consisting of resins consisting of structural units represented by the following formula is heat-treated in the presence of a catalyst consisting of metal powder and / or metal salt. Manufacturing method of scale carbon tube.

Item 2 The thermally decomposable resin is polyvinyl chloride,
Item 2. The method according to Item 1, which is at least one halogen-containing resin selected from the group consisting of chlorinated polyethylene and polyhexafluoropropylene.

Item 3 The thermally decomposable resin is (a) the general formula (1)

[0016]

[Chemical 7]

[In the formula, R ¹ represents an alkylene group having 1 to 10 carbon atoms, and X represents an oxygen atom. ] A resin comprising a structural unit represented by: and (b) a general formula (2)

[0018]

[Chemical 8]

[In the formula, R ² represents an alkyl group having 1 to 20 carbon atoms, a phenyl group or a substituted phenyl group. Item 1 or 2 above, which is at least one chalcogen-containing resin selected from the group consisting of resins consisting of structural units represented by
The manufacturing method described in.

Item 4 The catalyst consisting of metal powder and / or metal salt is at least one kind of metal, metal halide, metal nitrate and metal complex, and the metal is aluminum, iron, titanium, cobalt, manganese, tin, niobium,
Item 2. The production method according to Item 1, which is selected from the group consisting of copper, molybdenum, palladium, platinum, ruthenium, nickel, chromium and magnesium.

Item 5 The heat treatment is performed in an inert gas at 200 to 1
5. The production method according to any one of items 1 to 4, which is performed in a temperature range of 000 ° C.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the thermally decomposable resin used as a starting material is at least one selected from the group consisting of a halogen-containing resin and a chalcogen-containing resin. Such a thermally decomposable resin has a decomposition temperature of about 200 to 900 ° C (more preferably about 400 to 900 ° C).
Is preferred, but is not particularly limited.

Examples of the halogen-containing resin include polyvinyl chloride, chlorinated polyethylene, polyhexafluoropropylene and the like. These can be used alone or in combination of two or more. As these halogen-containing resins, those having a thermal decomposition temperature of about 200 to 500 ° C. are more preferable.

The following resins can be exemplified as the chalcogen-containing resin. (a) General formula (1)

[0025]

[Chemical 9]

[Wherein R ¹ is a phenylene group or a carbon number of 1
10 represents an alkylene group, and X represents an oxygen atom or a sulfur atom. ] A resin comprising a structural unit represented by the formula (b), a general formula (2)

[0027]

[Chemical 10]

[In the formula, R ² represents a hydrogen atom or a carbon number of 1 to 2.
0 represents an alkyl group, a phenyl group or a substituted phenyl group. ] The resin which consists of a structural unit represented by these. These can be used alone or in combination of two or more.

Examples of the resin composed of the structural unit represented by the general formula (1) include polyphenylene sulfide, polyphenylene oxide, polyalkylene oxide (the number of carbon atoms in the alkylene group is 1 to 10), and polyalkylene sulfide (alkylene group). Carbon number of 1 to 10) and the like. The weight average molecular weight of these resins is not particularly limited and a wide range can be used, but generally 200 to 2
It is preferably about 0,000, particularly about 20,000 to 40,000.

Further, in the general formula (2), the substituted phenyl group represented by R ² is an alkyl group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, a hydroxyl group and 1 to 5 carbon atoms. 1 selected from the group consisting of alkoxy groups
Examples thereof include phenyl groups having 5 to 5, especially 1 to 3 substituents. The resin composed of the structural unit represented by the general formula (2) is preferably polyalkyl acrylate, polyalkyl methacrylate, polyacrylic acid, polymethacrylic acid, or the like. The weight average molecular weight of these resins is not particularly limited and a wide range can be used, but generally 15
It is preferably about 000 to 1,000,000, particularly about 100,000 to 500,000.

The chalcogen-containing resin preferably has a thermal decomposition temperature of about 200 to 900 ° C, particularly about 400 to 900 ° C.

The shape of the heat decomposable resin as a starting material is
It may have any shape such as a film shape, a sheet shape, a powder shape, and a lump shape. For example, in the case of obtaining a carbon material in which a thin film amorphous nanoscale carbon tube is formed on a substrate, a heat-decomposable resin may be applied or placed on the substrate and subjected to excitation treatment under appropriate conditions. .

As the catalyst used in the heat treatment of the heat decomposable resin, metals such as aluminum, iron, titanium, cobalt, manganese, tin, niobium, copper, molybdenum, palladium, platinum, ruthenium, nickel, chromium and magnesium; Examples thereof include metal salts such as halides of these metals (in particular, fluorides, chlorides, bromides, iodides, etc.), nitrates of these metals, and complexes of these metals (eg, ferrocene). Among these catalysts, iron chloride (FeC
l ₂ , FeCl ₃ ), titanium chloride (TiCl ₄ ), iron nitrate (Fe (N
O) ₂ , Fe (NO) ₃ ) and metallic copper are more preferable. The particle size of the catalyst is not particularly limited, but is usually 5 mm or less, and more preferably 100 μm or less.

The heat treatment of the raw material thermally decomposable resin is carried out under an inert atmosphere (in the atmosphere of an inert gas such as Ar, He, N ₂ ; under pressure to under reduced pressure, preferably 0.1 Pa to 300 kPa, more preferably 10 Pa). Under reduced pressure of about 100 kPa) with the catalyst in contact with the raw material. Examples of the mode of bringing the catalyst into contact with the raw material include a state in which catalyst particles are provided on the surface of the raw material film or sheet, a state in which the raw material powder and the catalyst particles are mixed, and the like.

The amount of the catalyst used with respect to the raw material thermally decomposable resin may vary greatly depending on the shape and type of the raw material, the type and particle size of the catalyst, etc., but usually 10 to 1/1000 times the amount based on the raw material weight. The amount is about 1/10 to 1/50 times, and more preferably about 1/10 to 1/50.

The heat treatment is carried out at a temperature of 3000 ° C. or lower, preferably about 200 to 1000 ° C., more preferably 600 to 900 ° C. and above the thermal decomposition temperature of the raw material.

The amorphous nanoscale carbon tube obtained by the present invention is a nanoscale carbon tube having an amorphous structure, is a hollow linear shape, and has highly controlled pores. The shape thereof is mainly a column, a square pole, etc., and at least one of the tips does not have a cap (is open) in many cases. When the tip is closed, the shape is often flat.

The outer diameter of the amorphous nanoscale carbon tube according to the present invention is usually in the range of about 1 to 1000 nm, preferably about 1 to 200 nm, more preferably about 1 to 100 nm. The length / diameter of the tube is 2 times or more, preferably 5 times or more.

"Amorphous structure" means
It does not mean a graphitic structure composed of a continuous carbon layer of regularly arranged carbon atoms, but a carbonaceous structure composed of irregular carbon net planes. From an image obtained by a transmission electron microscope, which is a typical analysis method, the nanoscale carbon tube having an amorphous structure according to the present invention is defined such that the plane of the carbon mesh plane is smaller than 1 time the diameter of the carbon tube. it can.

Amorphous carbon generally does not show X-ray diffraction but shows broad reflection. In the graphitic structure, the carbon net planes are regularly stacked, so the carbon net plane spacing is
(d _{00 2} ) becomes narrower, and the broad reflection shifts to the high-angle side (2θ) and becomes sharper (the half-width of the 2θ band becomes narrower), and can be observed as d ₀₀₂ diffraction line (graphite-like). D ₀₀₂ = 3.3 when they are stacked regularly due to positional relationship
54Å).

On the other hand, the amorphous structure does not generally show diffraction by X-ray as described above, but partially shows very weak coherent scattering. X-ray diffraction method (incident X-ray is CuKα)
In, the theoretical crystallographic properties of the amorphous nanoscale carbon tube according to the present invention measured by the diffractometer method are defined as follows: The carbon net plane spacing (d ₀₀₂ ) is 3.54 Å or more. Yes, more preferably 4.3 Å or more; the diffraction angle (2θ) is 25.1 degrees or less, more preferably 24.1 degrees or less; the full width at half maximum of the 2θ band is 3.2 degrees or more, more preferably 7.0
More than a degree.

In the amorphous nanoscale carbon tube according to the present invention, such an amorphous structure (amorphous carbon) portion preferably accounts for more than 95% of the total, and preferably 99% or more of the total.

The term "straight line", which is one of the terms representing the shape of the amorphous nanoscale carbon tube of the present invention, is defined as follows. That is, when the length of the amorphous nanoscale carbon tube image by the transmission electron microscope is L and the length when the amorphous nanoscale carbon tube is extended is L ₀ , L / L ₀ becomes 0.9 or more. It shall mean a shape characteristic. In the present invention, such a linear amorphous nanoscale carbon tube preferably accounts for 90% or more of the entire amorphous nanoscale carbon tube, and more preferably 95% or more.

It has been reported that conventional carbon nanotubes (CNTs) may initially exhibit a gas storage property of hydrogen or the like, but no direct confirmation of the gas storage capacity has been performed. Therefore, the conventional CNT cannot be put to practical use as a gas storage material.

On the other hand, the amorphous nanoscale carbon tube according to the present invention is linear, the pores are highly controlled, and the gas can be diffused even between the carbon mesh planes, so that the inside of the hollow portion can be diffused. It absorbs the expansion and contraction of the material due to the physical adsorption of gas, and therefore exhibits the unique property of exhibiting a high degree of durability. Therefore, the amorphous nanoscale carbon tube according to the present invention is extremely useful as a gas storage material. As the stored gas, hydrogen and gases other than hydrogen (eg, methane, helium, neon, xenon, krypton, carbon dioxide, etc.)
Can be mentioned. Further, since the material of the present invention can control the pores on a molecular basis, it can also be used as a material for selectively adsorbing / occluding a specific compound or as a molecular sieve.

Further, the amorphous nanoscale carbon tube according to the present invention has an advantage that it does not require a complicated opening treatment because many of its ends have openings. In addition, many of the closed ends have a flat shape, and the structural strain at the ends is relatively large. Therefore, even in this case, the tube end can be easily opened. .

Furthermore, since the amorphous nanoscale carbon tube according to the present invention has a linear shape, it is possible to increase the density of the gas storage material, which is further advantageous for gas diffusion in the material.

Further, the amorphous nanoscale carbon tube according to the present invention or the carbon material containing the same has stretchability capable of absorbing an external force, and is therefore useful as a sliding material, a friction material and the like. .

The amorphous nanoscale carbon tube of the present invention may contain at least one kind of metal, metal salt, metal oxide and metal alloy. Such metals, metal salts, metal oxides, and metal alloys include metals constituting the catalyst, that is, aluminum, iron, titanium, cobalt, manganese, tin, niobium, copper, molybdenum, palladium, platinum, ruthenium, nickel, chromium. And at least one selected from the group consisting of magnesium, salts of these metals (especially halides, nitrates, etc.), oxides of these metals, alloys of these metals, and the like.

At least one of such metals, metal salts, metal oxides and metal alloys is continuously, intermittently or partially formed in the hollow portion surrounded by the tube wall of the amorphous nanoscale carbon tube over the entire length of the tube. In particular, it is contained in the form of whiskers, nanoclusters, carbides (carbon compounds) and the like. In some cases, the amorphous nanoscale carbon tube may be attached to the outer peripheral surface of the tube wall in the form of whiskers, nanoclusters, carbide (carbon compound), or the like.

When the amorphous nanoscale carbon tube according to the present invention or the carbon material containing the same is used as a negative electrode material of a lithium secondary battery, it is expected that a large capacity will be exhibited based on its characteristics. .

The amorphous nanoscale carbon tube or the carbon material containing the same according to the present invention can be used as a semiconductor material, a semiconductor fibril, an electron emitting material, etc.
It is useful.

[0053]

EXAMPLES The following will show Examples and Comparative Examples to further clarify the characteristics of the present invention.
It is not limited to these examples.

Examples 1 to 3 A powdery mixture of polyethylene glycol (PEG) having a weight average molecular weight of 35,000 and titanium chloride (TiCl ₄ ) in a weight ratio of 1: 1 was placed in a reaction furnace and depressurized to 10 Pa under an argon atmosphere. Reacted for hours. The reaction temperature is 500, 600 as shown in Table 1 below.
And set to 800 ° C.

[0055]

[Table 1]

As a result of SEM observation of the product, it was found that the product was a highly linear tube containing whiskers. The product yields are shown in Table 2 below.

[0057]

[Table 2]

In order to elucidate what the whiskers contained in the amorphous nanoscale carbon tube are in the above product, a part of the above product was taken out and subjected to XRD, Raman and SEM-EDX analysis. . The results are shown below.

[0059]

[Table 3]

In Table 3 above, each term has the following meaning.

SEM = scanning electron microscope * XRD = X-ray diffraction * C (d value) = graphite average interplanar distance (d ₀₀₂ ) determined by X-ray diffraction * R value = 1540 cm ⁻ obtained by Raman spectroscopy ¹ to 1650 cm
1200 of the integrated intensity (Ia) of the peak with the peak center at ^-1
the integrated intensity ratio for the integral intensity (Ib) of peaks with a peak from the center cm ^-1 to ^{1500cm -1 (Ia / Ib) ·} G band half width = 1200～1500Cm half width · SEM-EDX = scanning peaks ^-1 A device that combines a scanning electron microscope and a fluorescent X-ray analyzer.

From the analysis results in Table 3 above, it is understood that in Examples 1 to 3, amorphous nanoscale carbon tubes containing titanium oxide were produced. More specifically, from SEM-EDX, XRD, the needle-like substance is TiO ₂ , the main component is rutile type, the sub-component is anatase type,
Further, it was found from the d value of XRD that the crystallinity of carbon was low. This was consistent with the large G band half-width in the Raman scattering spectrum.

As a result of observing the products of Examples 1 to 3 by FE-TEM, it was confirmed that the central portion was TiO ₂ and the periphery was amorphous carbon, and the formation of an amorphous scale carbon tube.

The hydrogen storage capacity of the product of Example 2 was measured by the volumetric method. As a result, it was found to be 2.6% by weight at 10 MPa, and the amorphous nanoscale carbon tube of the present invention has a high hydrogen storage capacity. It was confirmed.

[0065]

According to the present invention, the following remarkable effects are achieved.

(A) It is possible to obtain a nanoscale carbon tube having a linear and stable amorphous structure of a nanoscale order which can be a novel storage material having excellent stable storage capacity for various gases and excellent durability.

(B) The heat decomposable resins used as raw materials are all easily available and inexpensive, and the yield and purity of the amorphous nanoscale carbon tubes are high.

(C) Since the amorphous nanoscale carbon tube producing a small amount of impurities or the carbon material containing it can be produced in a high yield, it is easy to purify and obtain a desired nanoscale carbon tube. It is mass-producible and can be manufactured industrially.

(D) Since such an amorphous nanoscale carbon tube has a hollow linear shape and can be formed into a thin film on a substrate, it is extremely useful as a material for electronic devices.

(E) Such an amorphous nanoscale carbon tube or a carbon material containing the same is a gas storage material, a highly elastic material, a high strength material, an abrasion resistant material,
Electron beam emitter, high directivity X-ray source, soft X-ray source,
It is useful as a one-dimensional conductive material, a high thermal conductive material, and other materials for electronic devices.

(F) In the case where the amorphous nanoscale carbon tube produced by the production method of the present invention contains a metal, a metal salt, a metal oxide, a metal alloy, etc. in the space surrounded by the tube wall. Even shows excellent hydrogen storage capacity. This is probably because the tube wall has an amorphous structure.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Haruyuki Nakaoka             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Katsuhide Okimi             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Ryoichi Nishida             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. (72) Inventor Takeo Matsui             17 Kyoto-shi Minami-cho, Shimogyo-ku, Kyoto             Search Park Kansai Research Institute of Technology             Within F-term (reference) 4G146 AA11 AD01 AD02 BA17 BC23                       BC32A BC32B BC33A BC33B                       BC43 BC44

Claims (5)

[Claims] 1. (A) At least one halogen-containing resin selected from the group consisting of polyvinyl chloride, chlorinated polyethylene and polyhexafluoropropylene, or (B) (a)
General formula (1) [In the formula, R ¹ represents a phenylene group or an alkylene group having 1 to 10 carbon atoms, and X represents an oxygen atom or a sulfur atom. ]
A resin comprising a structural unit represented by: (b) General formula (2) [In formula, R < ² > shows a hydrogen atom, a C1-C20 alkyl group, a phenyl group, or a substituted phenyl group. ] At least one chalcogen-containing resin selected from the group consisting of resins consisting of structural units represented by the following formula is heat-treated in the presence of a catalyst consisting of metal powder and / or metal salt. Manufacturing method of scale carbon tube. 2. The method according to claim 1, wherein the thermally decomposable resin is at least one halogen-containing resin selected from the group consisting of polyvinyl chloride, chlorinated polyethylene and polyhexafluoropropylene. 3. The thermally decomposable resin is (a) a compound represented by the general formula (1): [In the formula, R ¹ represents an alkylene group having 1 to 10 carbon atoms,
X represents an oxygen atom. ] A resin comprising a structural unit represented by the following, and (b) a general formula (2): [In formula, R < ² > shows a C1-C20 alkyl group, a phenyl group, or a substituted phenyl group. ] The manufacturing method of Claim 1 or 2 which is at least 1 sort (s) of chalcogen containing resin selected from the group which consists of resin which consists of a structural unit represented by this. 4. A catalyst comprising a metal powder and / or a metal salt is at least one of a metal, a metal halide, a metal nitrate and a metal complex, and the metal is aluminum,
Iron, titanium, cobalt, manganese, tin, niobium, copper,
The manufacturing method according to claim 1, which is selected from the group consisting of molybdenum, palladium, platinum, ruthenium, nickel, chromium and magnesium. 5. The heat treatment is carried out at 200 to 1000 in an inert gas.
The manufacturing method according to any one of claims 1 to 4, which is performed in a temperature range of ° C.