WO2004007363A1

WO2004007363A1 - Fine carbon sheet laminate having structure of week interlaminar bonding force and method for preparation thereof

Info

Publication number: WO2004007363A1
Application number: PCT/JP2003/008726
Authority: WO
Inventors: Kunio Nishimura; Takayuki Tsukada
Original assignee: Bussan Nanotech Research Institute Inc.
Priority date: 2002-07-16
Filing date: 2003-07-09
Publication date: 2004-01-22
Also published as: AU2003248258A1

Abstract

A fine carbon sheet laminate having a structure of week interlaminar bonding force, wherein at least two graphene sheets composed of carbon atoms having a long side of 100 nm or more and a short side of 3 nm or more are laminated, respective layers have long sides of a similar length and short sides being different in length, respective groups of carbon atoms constituting two adjacent layers coordinate with each other in a relationship exhibiting no crystallinity in the C0 direction, two layers are bonded with each other with a bonding force weaker than the van der Waals force required for forming a graphite structure, the distance between two adjacent layers is 0.344 nm or more, and chiralities of respective layers are combined at random; and a method for preparing the fine carbon sheet laminate which comprises pyrolyzing an organic compound containing a Group VI element of the Periodic Table in the presence of a transition metal ultra-fine particle catalyst.

Description

Specification

Fine carbon sheet laminate having a structure in which interlayer bonding strength is weak, and method of manufacturing the same

Technical field

The present invention relates to a fine carbon sheet laminate having a structure in which interlayer bonding is weak, and a method for producing the same. The sheet includes a flat sheet, a curved sheet, and a sheet that is not completely closed continuously.

Background art

In recent years, fine carbon materials that have attracted attention as basic materials for nanotechnology include fullerenes and fine carbon fibers. There are several types of fine carbon fibers depending on the fiber diameter, and they are called vapor-grown carbon fibers, carbon nanofibers, and carbon nanotubes.

The crystal structure of these fine carbon materials takes a variety of forms, such as a sheet in which carbon atoms are bonded in a hexagonal mesh (Graph Ensheet), a single carbon nanotube (SWNT) in which one layer is cylindrical, and a Graph Ensheet. There are multi-walled carbon nanotubes (MWNT) in which a number of cylinders are nested in layers. Further, there is a nanocone having a crystal structure intermediate between the two, that is, a cone-shaped crystal structure in which the crystal plane extends at a certain angle with respect to the central axis thereof.

Examples of the fine carbon material having a shape other than the tubular shape include a rifon-like fine carbon material having a structure in which a graph ensheet is laminated so as to be orthogonal to a fiber direction, and a coil-like fine material having an amorphous structure having no crystallinity. And carbon materials.

Among them, carbon nanotubes are the finest and have a fiber diameter of less than 100 nm, so the diameter and the geometrical shape (helical structure) of the winding of the sheet are determined by the chiral index, and the metal is determined by the chiral index. And properties of semiconductors. Its unique physical properties Therefore, it is expected to be widely applied to nanoelectronic materials, composite materials, catalyst support for fuel cells, etc., and gas absorption.

It is said that carbon nanotubes used as filler materials for electronic materials and composite materials preferably have good crystallinity, are straight, have a small fiber diameter, and are uniform. If it is curled instead of straight, the fibers tend to get entangled and become flocked. When it becomes a floc, it is difficult to grind, it is difficult to arrange fibers when used, and even when it is added to a resin or the like as a filler material, it is difficult to uniformly disperse it, making it difficult to obtain a composite material with desired characteristics . Therefore, it is currently considered difficult to use fine carbon sheets with incomplete crystal structures and tubes.

These fine carbon materials are synthesized by an arc discharge method using a carbon electrode, a laser oven method, or a method of chemically pyrolyzing hydrocarbon gas using transition metal fine particles as a catalyst (CVD method, CCVD method). .

By the way, as conventionally known carbon nanotubes,

1) The carbon nanotubes described in Hyperion, US Pat. No. 4,632,230, Japanese Patent Application Laid-Open No. 3-174018, etc. are fibrils substantially consisting of a continuous multilayer of carbon atoms having a graphite structure, and are regularly arranged. Consisting of multiple layers of aligned carbon atoms, each layer and core are arranged substantially concentrically with the fibril cylinder axis, and each carbon atom layer has its C axis substantially perpendicular to the fibril cylinder axis. It is a fibril made of graphite.

2) To date, many patent applications related to carbon nanotubes, including Hyperion's patents, have been filed, for example, in Japanese Patent Application Laid-Open Nos. 05-179514 (Nikkiso), 06-157016 (NEC), 06-280116 (NEC), 07- 150419 (Showa Denko), 08-100328 (Canon), 10-273308 (Mitsubishi Chemical), 11-116218 (Osaka Gas), 11-180707 (NEC), 11-1-2636 10 (Toyota), 2000-95509 ( Showa Denko), 2000-203819 (Osaka Gas), 2000-31 9783 (Nisshin Nanotech), 2001-80913 (Nikkiso), 2001-11 15342 (E-gi-in), etc., all of which are graphite or graphite-like It is prescribed to have a structure. That is, the layers are fixed to the tile in a graphitic manner. Furthermore, it is assumed that the graphitization factor g shown in Eq. (1), which is a standard method of expressing physical property values in carbon technology, takes a positive value.

g = (3.44-d ₀₀₂ ) / (3.44- 3.354) (1)

3) Soneda (“Hydrogen storage with carbon nanofibers”, NIRE News (National Institute for Environmental Science and Resources), December 1998) published an electron microscope (SEM) using carbon nanotubes deposited on metal surfaces from carbon monoxide. , TEM). According to the report, one carbon nanotube is "a layered structure of carbonaceous material that develops at a certain angle with respect to the fiber axis to form a conical structure." Observe to have. In addition, fibrous carbon in which another graph enclosure is growing specifically in the C-axis direction, that is, carbon nanotubes disclosed by Hyperion, etc., has a highly crystalline graphite structure. Reported.

4) A method of depositing a carbon crystal structure around a fine needle-like substance disclosed in JP-A-2001-342014. A method such as a melt spinning method disclosed in JP-A-2002-29719 clearly shows a graphitic carbon. A method for producing a carbon nanotube having a crystalline structure is disclosed.

These fine carbon fibers are formed by laminating a graph ensheet, winding in a tubular shape, and encasing the tube in a multilayered form.The graph encased has hexagonal meshes of carbon atoms formed without defects. .

On the other hand, the fine carbon sheet laminate of the present invention has a layer structure having a regularity and a strong bond like a graphite structure, because the graphene sheets having different chirality exist at random. Unlike the above, the degree of freedom between layers increases, Expected to be.

The present invention provides a fine carbon sheet laminate having a new structure different from a turbostratic structure and a method for producing the same.

In the fine carbon sheet laminate of the present invention, a graph ensheet composed of carbon atoms is laminated. The sheet includes a flat sheet, a curved sheet, and a multilayer sheet having a structure in which sheets that are not completely closed continuously as a tube are laminated. The long side of each sheet is almost the same length, at least 100 nm or more, the short side is 3 nm or more, preferably 10 nm or more, and the short side length of each sheet may be different. It is a laminate of fine carbon sheets, in particular with an interlayer distance between two adjacent layers of greater than 0.344 nm, preferably greater than 0.4 nm. Unlike conventional graphite, the carbon atoms that make up the layers exhibit crystallinity in the CO direction, unlike conventional graphite, because each layer has a chirality sheet with different chirality that is randomly combined. It is a fine carbon sheet laminate with a unique structure that does not have a 1: 1 ratio and has a unique structure in which the layers are bonded by a weak bonding force that is not bonded by van der Waals forces such as a graphite structure.

These fine carbon sheet laminates have the above-mentioned Graphitization factor g, which is a standard index indicating the physical state of graphite.

g = (3.44-d ₀₀₂ ) / (3.44-3.354) (1) may take a positive value of 0 or more, but it cannot be said that graphite is a graphite solely based on these physical properties. The lattice spacing (002), which is a parameter of the lattice spacing (002) in Angstroms, which is a parameter of d _M2 X-ray diffraction of the sheet laminate, is apparent from the analysis result of the electron microscope as though it has a graphite structure.

1) The width of the short side of each layer of the sheet is different. Also, the ends of each layer may be shifted in the long side direction. Therefore, when a flat plate is formed, a surplus occurs in the vertical and horizontal directions.

2) Since the chirality is not constant, the carbon position is different for each layer when it is made flat. Therefore, the number of carbon atoms in each graph sheet constituting the tube is 1 : Cannot respond to 1.

3) The graph ensheets that make up the present fine carbon sheet laminate have not only a perfect structure but also many defects. Therefore, the carbon atoms of the graph sheets constituting the adjacent layers cannot correspond to 1: 1.

Therefore, fine carbon fibers satisfying the above conditions do not have a graphite structure.

On the other hand, according to the definition of the turbostratic structure, a fine carbon sheet laminate that is long in the length direction and is perfectly configured cannot be said to be a turbostratic structure. Therefore, the fine carbon sheet laminate of the present invention does not have a graphite structure or a turbostratic structure.

That is, the fine carbon sheet laminate having a structure that is not graphite according to the present invention has a laminate structure having a flat, curved, or almost tube-like shape, and the mutual relationship of graph sheets is random. It is characterized by having a structure.

A laminate of fine carbon sheets having such a structure exhibits surprisingly significant industrial-use properties compared to conventional carbon nanotubes having a graphitic structure. First, since each graph ensheet is fixed by a loose coupling force with each other, each graph enclosure behaves as a single graph enclosure. The graphene sheet itself is tightly coupled (Rigid) between C and C by SP ² hybrid orbitals, and the Phonon phenomenon occurs. That is, the CC bond, which is harder than the bond between metal atoms, makes the conductivity of heat, that is, physical vibration, very high. The thermal conductivity of the CC bond is 2000 WZm ° K, which is more than several times that of the metal bond. In the fine carbon sheet laminate of the present invention, the graphene that constitutes the graphene mainly has a negative graph initiation factor, so that the daraphen layer can vibrate without receiving mutual interference. It is possible to have higher thermal conductivity than metal.

Secondly, for the same reason as above, there is no interference between the dalaphen layers, so that electrons can easily move, that is, the electric conductivity increases.

Third, due to the mutual structure different from graphite, resistance increases when a magnetic field is applied. This effect is manifested specifically as electromagnetic wave shielding, and converts absorbed electromagnetic waves into heat. It shows high stealth property by replacing.

Fourth, due to the mutual structure different from graphite, the outermost layer of the graph ensheet is less susceptible to electronic interference from inside the tube, and the electrons on the graph ensheet easily react with substances outside the tube. Become.

Moreover, in the fine carbon sheet laminate of the present invention, since the dalaphen layer is wide, other substances can be easily introduced between the layers. In other words, since the graph ensheet layer interval is wider than conventional carbon nanotubes, fullerenes, metal-encapsulated fullerenes, which have a high degree of freedom between layers and are relatively large,> It can be introduced between layers. This space can be secured if the distance between the layers is at least larger than 0.4 nm. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically showing a reaction apparatus of Example 1.

FIG. 2 is a diagram schematically showing a reaction apparatus of Example 2.

FIG. 3 is a transmission electron micrograph of the fine carbon sheet laminate obtained in Example 1.

FIG. 4 is a transmission electron micrograph of the fine carbon sheet laminate obtained in Example 2. BEST MODE FOR CARRYING OUT THE INVENTION

Although the interlayer distance of the present invention is greater than 0.344 nm, the chirality of such a fine carbon sheet laminate is determined by the molecular dynamics method. A simulation was performed using the method (for the molecular dynamics calculation method, see Shigeo Maruyama, "Carbon Nanotubes (2002) Chapter 7: Generation and Mechanism of Single-Walled Carbon Nanotubes").

As a result, the dollar constituting the fine carbon sheet laminate having such a large interlayer distance is obtained. Table 1 shows the chirality of the outer and inner layers of the fen sheet. It is clear that the chirality of the outer layer and the inner layer of such a fine carbon sheet laminate is stochastically determined, and in the case of a multilayer tube, it is probable that all layers have the same chirality. In this simulation, the chirality is calculated only at the extremes of metallic or semiconducting, but in reality, there is an intermediate chirality, so it is very unlikely that all layers will have the same chirality. With a low probability, it is clear that the fine carbon sheet laminate of the present invention has a random chirality.

The relationship between the outer layer and the inner layer

Interlayer distance [nm] Chirality of layer Probability of existence [%] Outer layer Inner layer

0. 376 Metallic Metallic 22.4 Metallic semiconductor 16.8 Semiconductor Metallic 15.0 Semiconductor Semiconductor 45.8

0.400 Metallic Metallic 12.2 Metallic semiconductor 15.7 Semiconductor Metallic 26.1 Semiconductor Semiconductor 46.1

0.431 Metallic Metallic 18.7 Metallic semiconductor 15.4 Semiconductor Metallic 21.1 Semiconductor Semiconductor 44.7 The fine carbon sheet laminate of the present invention can be manufactured by the following method.

A compound containing a Group VI element in the periodic table and an organic compound serving as a carbon source or an organic compound containing a Group VI element in the periodic table, using at least one transition metal or ultrafine particles of the compound as a catalyst. hydrogen compound, is introduced into the reactor together with a carrier gas consisting of methane or an inert gas, 2 X 1 0 ⁵ P a pressure below the reaction furnace temperature 6 0 O: ~ 1 2 5 0 ° C in a chemical heat Decomposition (CVD method).

Further, the transition metal catalyst may be used by being supported on a carrier (CCVD method).

Examples of the transition metal include iron, cobalt, nickel, yttrium, titanium, vanadium, manganese, chromium, copper, niobium, molybdenum, palladium, stainless steel, and platinum. As the transition metal compound, these oxides, nitrates, sulfates, acetates, chlorides and the like can be used.

The compounds containing group VI elements of the periodic table, C 0, C_〇 _2, alcohols such as methanol, ethanol, etc. as organic compounds, § seton, ketones such as methyl E chill ketone as containing oxygen Phenols such as phenol, cresol and the like; ethers such as getyl ether; aldehydes such as formaldehyde and acetoaldehyde; organic acids such as acetic acid, propionic acid, succinic acid and adipic acid; and methyl acetate; Esters such as ethyl acetate can be used. Compounds containing sulfur include sulfur alone, and H ₂ S, CS ₂ , S〇 ₂ , thiol, thioether, and thiophene. Next, the field of application of the fine carbon sheet laminate of the present invention will be described.

The fine carbon sheet laminate of the present invention has significant features as described above as compared with conventional carbon nanotubes, and thus has a wide range of applications.

The method of use is broadly classified into a method of using as a sheet and a method of using as a powder. When used as a sheet, there are fields that use characteristics such as electron emission capability and conductivity in addition to FEDs, semiconductor devices, and the like.

Depending on the type of application, 1) a 0-dimensional composite material, such as a slurry, 2) a linearly processed 1-dimensional composite material, It can be used for 3D composites such as 2D composites (cloth, film, paper) processed into a sheet shape, and 4) complex molded products and blocks.

By combining these forms with the desired functions, an extremely wide range of applications is possible. The following are examples when this is shown for each function.

1) Use of conductivity

It is suitably used as a conductive resin and a conductive resin molded product by being mixed with a resin, for example, for packaging materials, gaskets, containers, resistors, conductive fibers, adhesives, inks, and paints.

2) Using thermal conductivity

The same usage can be performed as in the case of using the conductivity.

3) Devices that use electromagnetic wave shielding

When mixed with resin, it is suitable as an electromagnetic wave shielding paint or an electromagnetic wave shielding material formed by molding.

4) Those that use physical characteristics

Used in rolls, brake parts, tires, bearings, gears, pantographs, etc. by mixing with resin and metal to enhance slidability.

In addition, it can be used for housing electric wires, home appliances, vehicles, bodies of airplanes, etc., and machines, making use of its lightweight and tough characteristics.

Many of these are used as fillers and can be used as substitutes for conventional carbon fibers and beads. For example, they are applied to battery pole materials, switches, and vibration-proof materials. Example Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. Example 1

Using a vertical reactor, the reactor was manufactured by the CVD method using the reactor shown in Fig. 1.

The raw material liquid was converted into minute droplets using an ultrasonic atomizer, and the droplets were carried into the system from the upper part of the reactor with the use of the Helium gas. Helium gas was flowed from the upper part to the lower part of the reactor as an atmospheric gas, and pyrolyzed under the following reaction conditions.

The product dropped by its own weight and was collected in the collection box at the lower part of the reactor and at Filluichi. Raw material liquid: ethanol dissolved 0.15 g of iron acetate 100 m1

Reactor: SiC tube with inner diameter of 76φ

Reactor temperature: 1200 ° C

Atmosphere gas: helium (200 ml / min) + hydrogen (40 ml / min) A transmission electron microscope (TEM) photograph of the obtained fine carbon sheet laminate is shown in FIG.

From this figure, it can be seen that a laminate of fine carbon sheets in which three layers of graphent are laminated at about 1 nm. In addition, it is shown that the mesh structure of the sheet is not perfect, and the graph ensheet is defective. Example 2

It was manufactured by the CCVD method using a horizontal reactor and the reactor shown in Fig. 2.

Catalyst preparation: 1.68 g of cobalt nitrate hexahydrate was dissolved in about 1 Om 1 of water, and 4 lm l of 0.14 M aqueous solution of ammonium molybdate was added and mixed. 75 g was mixed well in an evaporating dish to form a slurry. After drying in a dryer at 120 ° C for 1 晚, the mixture was ground in a mortar to prepare a catalyst.

Reactor: Horizontal tubular furnace with quartz reaction tube, catalyst particles are placed on a quartz plate and reacted It was set near the center of the tube.

Catalyst activation and reaction: Heated to 800 t: under argon flow, held for 30 minutes, then bubbling argon into ethanol heated to 50 ° C, and introducing ethanol vapor into the reactor. To react on the catalyst. After introducing steam for 30 minutes, cooling was performed while flowing only argon gas, and then the product was taken out.

FIG. 4 shows a TEM photograph of the obtained fine carbon sheet laminate.

From this figure, it is shown that the graph ensheet has two layers of graph ensheets and has many defects as in Example 1. Industrial applicability

The fine carbon sheet laminate of the present invention is suitable as a conductive resin mixed with a resin, an electromagnetic wave shielding paint, and molded into a conductive resin molded article, an electromagnetic wave shielding material and the like.

In addition, it is mixed with resin and metal to improve the slidability, and is used for rolls, brake parts, gears, bearings, gears, pan and night graphs, etc. · Available for aircraft body, machine housing.

Claims

The scope of the claims

1. At least two graph ensheets composed of carbon atoms, the sheets having a long side of at least 100 nm or more are laminated in multiple layers, and the long sides of each layer are almost the same. The carbon atoms that constitute the adjacent layers have a coordination relationship with no crystallinity in the C0 direction, and the layers are bonded with a bonding force that is weaker than the van der Waals force required to form a graphite structure. A fine carbon sheet laminate having a structure in which the bonding strength between layers is weak.

2. The fine carbon sheet laminate according to claim 1, wherein the lengths of the short sides of the laminated graph sheets are different from each other.

3. The fine carbon sheet laminate according to claim 1 or 2, wherein the length of the short side of the laminated graph ensheet is 3 nm or more.

4. The fine carbon sheet laminate according to any one of claims 1 to 3, wherein the long sides of the laminated Dalafen sheets are different from each other.

5. The fine carbon sheet laminate according to any one of claims 1 to 4, wherein chirality of sheets constituting adjacent layers of the laminated graph ensheets is randomly combined.

6. The fine carbon sheet laminate according to any one of claims 1 to 5, comprising a sheet in which the network structure of the laminated graph enclosure is not perfect.

7. The fine carbon sheet laminate according to any one of claims 1 to 6, wherein carbon atoms constituting a network structure of adjacent layers in the laminate structure do not regularly correspond to 1: 1.

8. A tube-shaped sheet laminate in which the fine carbon sheet laminate according to claims 1 to 7 is wound in the short side direction, but is not completely closed continuously.

9. A fine carbon sheet laminate according to claim 8, wherein an aspect ratio, which is a ratio of the length of the fine carbon sheet laminate to the incomplete tube, is 100 or more.

10. The fine coal according to claim 9, wherein the aspect ratio is 100 000 or more. Element sheet laminate.

11. The method according to claim 1, which has a structure in which a hollow portion formed between layers of the fine carbon sheet laminate composed of a graphene sheet is filled with fullerene, metal-encapsulated fullerene, metal atoms and / or metal atom ions. The fine carbon sheet laminate according to any one of the above.

12. In a method for producing a fine carbon sheet laminate composed of a graphitic sheet, a compound containing a Group VI element of the periodic table using at least one kind of transition metal or ultrafine particles of the compound as a catalyst according to any one to no claim 1, wherein you chemical pyrolysis (CVD) 1 1 the organic compound containing a group VI element of the organic compound or the periodic table under 2 X 1 0 ⁵ P a pressure below the A method for producing a fine carbon sheet laminate.

13. In a method for producing a fine carbon sheet laminate composed of a graphitic sheet, at least one kind of transition metal or an ultrafine catalyst of a compound thereof is supported on a carrier, and a group VI element of the periodic table is provided. containing compound and an organic compound or an organic compound containing a group VI elements of the periodic table 2 X 1 0 ⁵ P a following catalytic chemical vapor phase synthesis method you pyrolysis under pressure (CCVD method) by the claims The method for producing a fine carbon sheet laminate according to any one of ranges 1 to 11.