JP2006144169A - Moustache fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new carbon fiber having specific shape (called Moustache fiber) and a method for producing the same. <P>SOLUTION: The Moustache fiber has a length of 1 μm to 1 mm, a diameter at the central part of 0.1 μm to 10 μm with bilateral symmetry and has a structure that the fiber diameter is narrowed uniformly from the central part toward the edge point and the diameter at the edge point is less than 100 nm. In a preferred embodiment, the fiber mainly comprises carbon and a metal and the metal content is more than 10% at the edge point and is more than 1% at the central part and the carbon content is more than 95 wt.% at the part other than the central part and the edge point parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mustache fiber which is a carbon fiber having a special shape, in particular, a mustache fiber mainly composed of carbon and metal, and a method for producing the mustache fiber.

  Carbon fiber has been studied for over 50 years, and is particularly used as a reinforcing material as a fiber excellent in durability and mechanical strength (see, for example, Non-Patent Document 1). Currently, carbon fibers are mainly produced by graphitizing polyacrylonitrile (PAN) fibers. While PAN-based carbon fibers have excellent strength, they also have the disadvantage of incomplete graphitized structures due to structural defects derived from PAN fibers. As another method, carbon fibers are also produced by graphitizing pitch fibers. The pitch is obtained by heat treating heavy oil. Pitch-based carbon fibers are composed of irregularly laminated graphite with a fine plate-like crystal structure and are characterized by a high degree of graphitization and an excellent Young's modulus, but also have the disadvantage of low tensile strength and compressive strength.

  As a method for producing carbon fibers, a chemical vapor deposition method (hereinafter referred to as a CVD method) in which a carbon compound (benzene, CO, etc.) is contacted with catalytic metal fine particles at a high temperature and thermally decomposed is also known. (For example, refer nonpatent literature 2) Unlike PAN or pitch fiber, the structure of the carbon fiber made by CVD is comprised by the cylinder laminated | stacked concentrically, and has a cavity in the center. Applications to materials for fuel cells or hydrogen storage are expected. In the CVD method, carbon nanotubes can also be produced by changing the type of carbon compound and the temperature conditions. (For example, see Non-Patent Document 3 or Non-Patent Document 4) A carbon nanotube is a substance in which a graphite sheet composed of a carbon 6-membered ring grows in a cylindrical shape, and has excellent mechanical properties. Research for practical application of devices, conductive electronic materials, hydrogen storage materials, etc. is underway.

  As a CVD method, a method of supporting a catalyst metal on a carrier is known. (See Patent Document 1) As a carrier, a porous carrier of silica powder or alumina powder, or a surface of Co-Ni treated with hydrochloric acid is used. Since carbon fibers or carbon nanotubes grow on the support, there is a disadvantage that they are not suitable for mass production.

As an alternative method, a method of floating a catalytic metal in the gas phase is also known (see Patent Document 2). In this method, the catalyst is supplied as vapor or gas without using a carrier. Various metal compounds can be used as the catalyst, but ferrocene Fe (C ₅ H ₅ ) ₂ and iron pentacarbonyl Fe (CO) ₅ are particularly used. The metal compound is supplied as vapor or gas from a container outside the CVD chamber to the chamber. When this metal compound is thermally decomposed in a high-temperature CVD chamber, condensed nano metal fine particles are generated, and carbon fibers or carbon nanotubes grow from the surface of the fine particles. Since this method does not require the use of a support material, carbon nanotubes with high purity can be produced. However, since it is difficult to control the size of the generated metal fine particles by this method, it is difficult to control the diameter and structure of the carbon fiber or carbon nanotube.

In the production of carbon nanotubes by this method, the HipCo method is known. In this method, high pressure is applied in the CVD chamber while supplying Fe (CO) ₅ (see, for example, Non-Patent Document 5). Therefore, small-sized fine particles are generated by rapid metal condensation, and the obtained carbon nanotubes are single-walled. However, since the HipCo method uses a high pressure, it has a drawback that the catalyst concentration during the reaction cannot be controlled, and is not suitable for mass production.

  Recently, the present inventors have invented a new carbon nanotube CVD method (Japanese Patent Application No. 2004-173782). In this method, a carbon nanotube is produced by bringing a gas of a compound serving as a carbon source into contact with a vapor or gas of a metal compound that is not thermally decomposed in a high-temperature CVD chamber. Here, in order to supply the metal compound as vapor or gas, it is inserted as a solid or liquid at room temperature into a container provided with an outlet, and the container is placed in a heated place in the quartz outer tube. Carbon nanotubes grow in the gas phase and deposit on the inner wall of the chamber.

  The present invention relates to a new carbon fiber (hereinafter referred to as “Mustache fiber” in French “MUSTACHE”) and a method for producing Mustache fiber.

JP 2002-255519 A, page 3 Japanese Patent No. 2899407, page 2 Donnet J. et al. B. et al. (Editors), Carbon Fibers-3rd Ed. , New York, Marcel Dekker Inc, 1998. A. Oberlin, and M.M. Endo, J. et al. of Cryst. Growth, 32 335-349, 1976 Jpn. J. et al. Appl. Phys. 37 (1998) L1257-L1259 Chem. Phys. Lett. 360 (2002) 229-234 J. et al. Vac. Sci. Technol. A 19 (4) (2001) 1800-1805

  It is an object of the present invention to provide a mustache fiber which is a carbon fiber having a special shape, particularly a mustache fiber mainly composed of carbon and metal, and a production method for obtaining the fiber in high purity and in a large amount.

The present invention relates to 1. This is a bilaterally symmetric fiber having a length of 1 μm to 1 mm and a central portion diameter of 0.1 μm to 10 μm, and has a structure in which the diameter decreases uniformly from the center toward the tip, and the tip portion has a diameter of 100 nm or less. , Mustache fiber mainly composed of carbon and has a graphite structure.

  2. Furthermore, it is a mustache fiber containing a metal, the tip portion of the fiber has a metal content of 10% or more, the center portion of the fiber has a metal content of 1% or more, and the portions other than the center and the tip contain carbon The mustache fiber according to the above, wherein the amount is 95% by weight or more.

  3. The above-mentioned Mustache fiber (hereinafter referred to as Mustache fiber α), characterized in that a metal is present in a ring shape on the circumference of the Mustache fiber in the central portion of the Mustache fiber.

  4). The central portion of the mustache fiber is composed of a bundle of 2 to 1000 fine fibers, and the length of the bundle is 1% to 99% of the length of the mustache fiber, The above-mentioned Mustache fiber (hereinafter referred to as Mustache fiber β), wherein metal is present in a ring shape on the circumference of the fine fiber.

  5. The graphite structure layer other than the central portion and the tip portion of the mustache fiber or the fine fiber in the bundle of Mustache fiber β is partially positioned perpendicular to the fiber axis, or partially as a conical structure on the fiber axis. The mustache fiber according to the above, which is laminated.

6). MX _n (where M is an atom belonging to Group VIIIA of Mendeleev's periodic table, X is an atom belonging to Group VIIB of Mendeleev's periodic table, n = 1, 2, 3 or 4) Reaction of vapor or gas (hereinafter sometimes referred to as A) with a carbon compound gas (hereinafter sometimes referred to as B) by a chemical vapor deposition (hereinafter referred to as CVD) method at a temperature between 300 ° C. and 2000 ° C. The method for producing Mustache fiber as described above, wherein

7). The method for producing Mustache fibers as described above, wherein A is at least one selected from the group consisting of FeCl ₂ , FeCl ₃ , CoCl ₂ , CoCl ₃ , NiCl ₂ , and NiCl ₃ .

8). B is selected from the group consisting of C _a H _{2a + 1} OH (a = 1-10), C _b H _{2b + 2} (b = 1-10), benzene, toluene, xylene, phenol, acetone, acetylene, ethylene, and carbon monoxide. The method for producing Mustache fiber according to the above, wherein the method is at least one kind.

9. The method for producing Mustache fibers according to the above, wherein the reaction is carried out at a weight ratio of A / B between 10 ⁻³ and 10.

By the production method of the present invention, novel Mustache fibers can be obtained in high purity and in large quantities. The Mustache fiber of the present invention is excellent in compressive strength and is expected to be suitably used as a Li and / or H ₂ absorbent.

The Mustache fiber of the present invention will be described below.
The Mustache fiber of the present invention is a symmetrical fiber having a length of 1 μm to 1 mm and a central portion having a diameter of 0.1 μm to 10 μm, and has a structure in which the diameter decreases uniformly from the center toward the tip. It is a fiber mainly composed of carbon and having a graphite structure with a diameter of 100 nm or less. Mustache fibers are stiff fibers, but are usually not straight and have some curvature like a beard.

  In the present invention, the mustache fiber is particularly preferably a fiber mainly composed of carbon and metal, and the portion other than the center and tip of the mustache fiber has a carbon content of 95% by weight or more, and is partially a graphite structure. Consists of. The tip portion of the fiber preferably has a metal content of 10% or more. This tip consists of normally arranged carbon nanoparticles, which may contain metal. The central portion of the fiber has a metal content of 1% or more. Depending on the structure of the central portion, the mustache fibers are roughly classified into two types.

  In the mustache fiber α, in one fiber, the metal present in the central portion is present in a ring shape on the circumference of the mustache fiber. Usually, this ring is not a uniform shape, but is composed of a group of nanoparticles arranged in a ring shape on the circumference of the fiber, and these nanoparticles are carbon containing metal.

  Mustache fiber β is composed of a bundle of several fine fibers (2 to 1000) in the central portion. The length of this bundle is 1% to 99% of the length of the Mustache fiber. Each metal present in the central portion of the Mustache fiber β is present in a ring shape on the circumference of the fine fiber in the bundle. Usually, this ring does not have a uniform shape, but is composed of a group of nanoparticles arranged in a ring shape on the circumference of fine fibers, and these nanoparticles are carbon containing metal.

  The graphite structure layer of the portion other than the center and the tip of the fine fiber in the bundle of Mustache fiber or Mustache fiber β is partially positioned perpendicular to the fiber axis, or partially laminated as a conical structure on the fiber axis. Often to do.

Then, the manufacturing method of the mustache fiber of this invention is demonstrated below. The Mustache fiber of the present invention is MX _n (where M is an atom belonging to Group VIIIA of Mendeleev's periodic table, X is an atom belonging to Group VIIB of Mendeleev's periodic table, n = 1, 2, 3 or 4). Chemical vapor deposition (hereinafter, referred to as “vapor” or gas of a metal compound (hereinafter also referred to as “A”) and a gas of a carbon compound (hereinafter also referred to as “B”) at a temperature between 300 ° C. and 2000 ° C. It can be produced by reacting by a CVD method. In addition, the Mustache fiber of the present invention including the Mustache fiber α or Mustache fiber β can be preferably produced by this method.

  In the present invention, the Mustache fiber is produced by contacting a vapor of a metal compound with a gas of a carbon compound serving as a raw material carbon source by chemical vapor deposition (hereinafter referred to as CVD). FIG. 2 is a schematic view of a CVD apparatus for manufacturing. The CVD apparatus basically includes an electric furnace, a quartz outer tube, a gas introduction system, and an exhaust system. Although not shown, it is also preferable that a temperature control system, a vacuum control system, a gas flow meter, a vacuum pump, and the like are installed. The metal compound is inserted as a solid or liquid into a container equipped with an outlet at room temperature to be supplied as vapor or gas, and the container is placed in a heated place in the quartz outer tube. Is preferred. The outlet diameter of the container is preferably in the range of 1 mm to 5 mm. Mustache fibers grow in the gas phase and deposit on the inner wall of the chamber. In order to obtain mustache fibers, it is preferable to attach a quartz inner tube.

  Using this apparatus, Mustache fibers can be produced, for example, by the following procedure. A metal compound is placed in a container as a solid or liquid, placed in a quartz tube, and heated. Inert gas (argon, nitrogen, etc.) is conducted until the electric furnace reaches the production temperature of Mustache fiber. When the temperature rises, the metal compound becomes vapor or gas (A). Next, the flow of the inert gas is stopped and the carbon compound gas (B) is allowed to flow at an appropriate flow ratio. Here, in the case of a carbon compound having a low vapor partial pressure, it is exhausted using a pump while introducing a carbon compound gas. At this time, the inside of the quartz tube can be maintained at a constant pressure by adjusting the pump speed. The production temperature of mustache fiber is maintained for several minutes to several hours and allowed to react. After the reaction is completed, the flow of the carbon compound gas is stopped, an inert gas is supplied at an appropriate flow ratio, the heating is stopped, and the temperature is lowered. When room temperature is reached, stop the flow of inert gas. Since mustache fiber is deposited on the inner wall of the quartz tube, it can be easily collected. Further, during the reaction, an inert gas such as a carbon compound gas can be conducted.

The metal compound constituting A is MX _n (where M is an atom belonging to Group VIIIA of the Mendeleev periodic table, X is an atom belonging to Group VIIB of the Mendeleev periodic table, n = 1, 2, 3 or 4 ). The metal compound constituting A is preferably a vapor or gas that does not decompose below the production temperature of the Mustache fiber. Preferred examples of M in MX _n include Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt. Preferred examples of X in MX _n include F, Cl, Br, I, and At. be able to. In MX _n , n = 1, 2, 3 or 4. As A, FeCl ₂ , FeCl ₃ , CoCl ₂ , CoCl ₃ , NiCl ₂ , and NiCl ₃ are preferable _{, and} among them, FeCl ₂ or FeCl ₃ is particularly preferable.

As a carbon compound which comprises said B, the gas which reacts with said metal compound below the production temperature of Mustache fiber is preferable. For example, alcohols represented by C _a H _{2a + 1} OH (a = 1-10), hydrocarbon compounds represented by C _b H _{2b + 2} (b = 1-10), benzene, toluene, xylene, phenol, acetone, acetylene , Ethylene, carbon monoxide and the like can be preferably used.
The weight ratio of A / B during the reaction is preferably between 10 ^{−8 and} 10 ³ , more preferably between 10 ^{−3 and} 10.

  The Mustache fiber can be suitably obtained by the method as described above. In addition, the purity, production amount, and crystallinity of the mustache fiber can be controlled by suitably selecting the metal compound, the carbon compound, the production temperature condition, and the location where the mustache fiber is collected in the chamber in the above production method. . When importance is attached to purity, it is preferable to obtain mustache fibers at a location near the gas inlet of the carbon compound. (The purity described below is the total weight of the mustache fiber and the metal present in the mustache fiber with respect to the total amount of the obtained powder.) The purity of the mustache fiber thus obtained is 50% by weight or more. Preferably they are 95 weight% or more and 100 weight% or less. When importance is attached to mass productivity, it is preferable to use acetylene as the carbon compound of B.

  Hereinafter, the method of the present invention will be described in more detail with reference to examples. However, these examples do not limit the scope of the present invention.

100 mg of FeCl ₂ powder was placed on a 2 × 15 cm magnetic plate, and the FeCl ₂ powder was covered with a 3 × 0.5 × 0.5 cm magnetic boat on the plate. (There was a gap of 300 microns or less between the board and the boat). This was installed in a 1 liter quartz tube of a CVD apparatus, the quartz tube was sealed and evacuated by a pump. After confirming that the vacuum was 10 Pa or less, the pump was stopped, argon was introduced, and the argon flow rate was set to 100 ml / min under a stable condition of a pressure of 10 ⁵ Pa. The inside of the CVD apparatus was heated from room temperature to 500 ° C. in 20 minutes. (When the temperature rises, the FeCl ₂ powder becomes an FeCl ₂ liquid and vapor (metal compound of A).) After confirming that the inside of the CVD apparatus has reached 500 ° C., the introduction of argon is stopped, and the acetylene gas ( B carbon compound) was introduced at a flow rate of 50 ml / min and reacted. Ten minutes after the reaction time, the introduction and heating of acetylene were stopped and the flow rate was set to 100 ml / min of argon. After confirming that the inside of the CVD apparatus was cooled to 200 ° C. (7 minutes later), the introduction of argon was stopped. After confirming that the inside of the CVD apparatus had returned to room temperature, the quartz tube was opened, and gray and wooly Mustache fibers were deposited on the outer periphery of the magnetic boat on the magnetic plate, and this was collected.

  The result of having observed the obtained Mustache fiber with the transmission electron microscope (TEM) is shown to FIGS. As a result, it was confirmed that a high-purity mustache fiber was produced. Two types of Mustache fiber α (FIG. 3) or Mustache fiber β (FIG. 4) were observed depending on the location obtained. The amount of wool fiber obtained as a whole was 10 mg. The purity of Mustache fiber, that is, the ratio of the amount of Mustache fiber (including the metals present in Mustache fiber) to the amount of powder obtained, estimated by a statistical method using TEM, was 90% or more. . A ring-like metal was present around the central portion of each Mustache fiber α or fine fiber in Mustache fiber β bundle. The tips of each Mustache fiber consisted of aligned carbon nanoparticles. Metals were sometimes contained in the nanoparticles. Electron diffraction by TEM (FIG. 5) confirmed that the carbon was incomplete but had crystallinity. The graphite structure layer was not parallel to the fiber axis but was positioned almost perpendicularly. In addition, diffraction confirmed two symmetric radiation spots on both sides of the fiber axis, and there was a portion where the graphite structure layer was laminated as a conical structure on the fiber axis.

The schematic diagram of Mustache fiber of the present invention 2.3.4.5. The schematic diagram of the CVD apparatus in the manufacturing method of this invention. The transmission electron micrograph of Mustache fiber alpha of an example. The transmission electron micrograph of Mustache fiber (beta) of an Example. The transmission electron microscope diffraction photograph of Mustache fiber alpha of an Example.

Explanation of symbols

1. 1. Electric furnace 2. Quartz outer tube 3. Quartz inner tube 4. Metal compound container 5. Solid or liquid metal compound 6. Metal compound vapor or gas 7. Gas of carbon compound Entrance 9. Exit 10. Reaction zone

Claims (9)

  This is a bilaterally symmetric fiber having a length of 1 μm to 1 mm and a central portion diameter of 0.1 μm to 10 μm, and has a structure in which the diameter decreases uniformly from the center toward the tip, and the tip portion has a diameter of 100 nm or less. , Mustache fiber mainly composed of carbon and has a graphite structure.   Furthermore, it is a mustache fiber containing a metal, the tip portion of the fiber has a metal content of 10% or more, the center portion of the fiber has a metal content of 1% or more, and the portions other than the center and the tip contain carbon The mustache fiber according to claim 1, wherein the amount is 95% by weight or more.   The mustache fiber (hereinafter referred to as mustache fiber α) according to claim 2, wherein a metal is present in a ring shape on the circumference of the mustache fiber in the central portion of the mustache fiber.   The central portion of the mustache fiber is composed of a bundle of 2 to 1000 fine fibers, and the length of the bundle is 1% to 99% of the length of the mustache fiber, The mustache fiber (hereinafter referred to as mustache fiber β) according to claim 2, wherein a metal is present in a ring shape on the circumference of the fine fiber.   The graphite structure layer other than the central portion and the tip portion of the mustache fiber or the fine fiber in the bundle of Mustache fiber β is partially positioned perpendicular to the fiber axis, or partially as a conical structure on the fiber axis. The mustache fiber according to any one of claims 1 to 4, which is laminated. MX _n (where M is an atom belonging to Group VIIIA of Mendeleev's periodic table, X is an atom belonging to Group VIIB of Mendeleev's periodic table, n = 1, 2, 3 or 4) Reaction of vapor or gas (hereinafter sometimes referred to as A) with a carbon compound gas (hereinafter sometimes referred to as B) by a chemical vapor deposition (hereinafter referred to as CVD) method at a temperature between 300 ° C. and 2000 ° C. The method for producing Mustache fiber according to any one of Claims 1 to 5, wherein Method for producing Musutashu fiber according to claim 6, characterized in that A is _{FeCl 2, FeCl 3, CoCl 2} , CoCl 3, NiCl 2, and at least one selected from the group consisting of NiCl _3. B is selected from the group consisting of C _a H _{2a + 1} OH (a = 1-10), C _b H _{2b + 2} (b = 1-10), benzene, toluene, xylene, phenol, acetone, acetylene, ethylene, and carbon monoxide. The method for producing Mustache fiber according to claim 6 or 7, wherein the method is at least one kind. The method for producing Mustache fibers according to any one of claims 6 to 8, wherein the reaction is carried out at a weight ratio of A / B between 10 ^-3 and 10.

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