JP2010143803A - Method of carbon fiber orientation and carbon fiber orientation unit, and method of manufacturing carbon fiber dispersed on cathode electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of carbon fiber orientation to align the carbon fiber contained in a cathode electrode perpendicular to an anode electrode. <P>SOLUTION: Since an electric field directing from a cathode electrode 2 to an anode electrode 3 is generated by impressing a reverse bias voltage between the cathode electrode 2 and the anode electrode 3 of a carbon fiber orientation unit 1, the carbon fiber 9 in the cathode electrode 2 receives a force from the electric field, and is aligned to the direction towards the anode electrode 3 in a state of forming a bundle structure. To the bundle-structured carbon fiber 9 aligned in perpendicular direction to the cathode electrode 2, acts a repulsive force only to the horizontal direction to the cathode electrode 2, and since the repulsive force is greater than van der Waals force acting on the carbon fiber 9, the bundle structure of the carbon fiber 9 is resolved and the carbon fiber 9 can be sufficiently dispersed on the cathode electrode 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing carbon fibers dispersed on a cathode electrode.

  A light emitting device comprising an anode electrode containing a fluorescent material, a cathode electrode arranged opposite to the anode electrode, and a voltage applying means for applying a forward bias voltage between the cathode electrode and the anode electrode is provided for information equipment and AV equipment. It is used as a display device. There is also known a light emitting device in which a large number of carbon fibers are arranged on the cathode electrode to improve the light emission efficiency.

  The cathode electrode of such a light-emitting device can be obtained by mixing carbon fiber with a solvent to form a paste, applying the paste to the cathode electrode, and then performing a heat treatment. However, the carbon fibers in the cathode electrode obtained in this way are entangled with each other to form a bundle, and the directions of the carbon fibers are not uniform. As a result, the electric field is less likely to concentrate at the tip of the carbon fiber, and the direction in which electrons jump out varies, making it difficult to control the focus characteristics. As a result, there is a problem that sufficient light emission cannot be obtained.

  In order to solve this problem, Patent Document 1 applies a voltage (forward bias voltage) that causes the anode electrode layer to have a positive potential with respect to the cathode electrode including carbon nanotubes. A method for manufacturing an electron emission source is proposed in which an electric field is generated between the carbon nanotubes and the carbon nanotubes are vertically aligned by the force of the electric field.

  Patent Document 2 discloses a first step of sequentially stacking a cathode electrode layer, an insulating layer, and a gate electrode layer on one surface of an insulating substrate, and a gate hole in a state where the cathode electrode layer is partially exposed on the insulating substrate. A second step of forming, a third step of forming an emitter with a plurality of carbon-based needles on the cathode electrode layer in the gate hole, and applying a voltage to the cathode electrode layer to A method of manufacturing an electron-emitting device including a fourth step of orienting a plurality of carbon-based acicular substances substantially vertically is proposed.

JP 2000-294119 A JP 2004-55484 A

  However, in the manufacturing method of Patent Document 1, field emission occurs when the electric field between the anode electrode and the cathode electrode is generated in a vacuum, and discharge occurs when the electric field is generated at atmospheric pressure. Therefore, a large voltage is applied to the anode electrode layer. It was not possible to apply between the cathode electrodes. Therefore, the force to orient the carbon nanotubes vertically is weak, and it is difficult to orient the carbon nanotubes perpendicularly to the cathode electrode.

  In addition, the manufacturing method of Patent Document 2 uses a repulsive force that is generated when a carbon-based acicular substance and a cathode electrode layer are given the same polarity of charge. Since the force for aligning the direction of the substance is weak, it is difficult to align the direction of the carbon-based acicular substance in the direction perpendicular to the cathode electrode layer even by the manufacturing method of Patent Document 2.

  Therefore, in the manufacturing methods of Patent Document 1 and Patent Document 2, it has been difficult to sufficiently disperse carbon nanotubes and the like on the cathode electrode.

  The present invention has been made under such a background. A carbon fiber aligning method and a carbon fiber aligning apparatus for aligning carbon fibers contained in a cathode electrode vertically to an anode electrode, and the carbon fiber aligning device, and the cathode electrode are dispersed on the cathode electrode. A method for producing a carbon fiber is provided.

  According to a first aspect of the present invention, there is provided a carbon fiber orientation method comprising: preparing a cathode electrode containing carbon fiber; and an anode electrode disposed to face the cathode electrode, and the gap between the cathode electrode and the anode electrode. A reverse bias voltage is applied.

  A carbon fiber orientation device according to a second aspect of the present invention includes a cathode electrode containing carbon fibers and an anode electrode disposed opposite to the cathode electrode, and a reverse bias is provided between the cathode electrode and the anode electrode. Voltage applying means for applying a voltage is provided.

  A method for producing carbon fibers dispersed on a cathode electrode according to a third aspect of the present invention comprises preparing a cathode electrode containing carbon fibers and an anode electrode disposed to face the cathode electrode, and the cathode electrode A reverse bias voltage is applied between the anode electrode and the anode electrode.

  According to the present invention, it is possible to apply a reverse bias voltage between the cathode electrode and the anode electrode so that the orientation of the carbon fibers contained in the cathode electrode is aligned vertically toward the anode electrode. The fibers can be sufficiently dispersed.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual configuration diagram of a carbon fiber orientation device showing an embodiment of the present invention.

The carbon fiber orientation device 1 is a device that aligns carbon fibers contained in a cathode electrode vertically toward an anode electrode, and is composed of a cathode electrode 2, an anode electrode 3, and a voltage applying means 4, as shown in FIG. . The cathode electrode 2 and the anode electrode 3 are arranged to face each other so that the distance between them is 100 μm or less, preferably 50 μm, and is sealed inside the casing 5 having airtightness. The inside of the casing 5 is kept at a vacuum of 10 ⁻² Torr or less.

  The cathode electrode 2 is configured by laminating a cathode conductor layer 7 mainly composed of silver on a cathode substrate 6 made of an insulating material (for example, glass), and further laminating a carbon layer 8 thereon. . The cathode conductor layer 7 has a thickness of about 5 μm, and the carbon layer 8 has a thickness of about 1 μm to 10 μm.

  The carbon layer 8 is a layer of carbon fibers 9 obtained by applying a paste containing carbon fibers 9 on the cathode conductor layer 7 and then heat-treating to remove the solvent component in the paste.

  The anode electrode 3 is formed by forming a thin film of indium oxide and tin composite oxide (ITO; (Indium Tin Oxide)) on an anode substrate 10 made of an insulating material (for example, glass) to form an anode conductor layer 11. Formed and configured. The thickness of the anode conductor layer 11 is about 5 μm.

  The voltage application unit 4 includes a power supply device 12 and a switch 13. The power supply device 12 is a DC power supply device that applies a reverse bias voltage between the cathode electrode 2 and the anode electrode 3. The positive electrode 14 of the power supply device 12 is connected to the cathode conductor layer 7, and the negative electrode 15 is connected to the anode conductor layer 11. Connected. The switch 13 is in an electric circuit between the negative electrode 15 of the power supply device 12 and the anode conductor layer 11 and opens and closes the electric circuit.

  If the pulse voltage generator is used as the power supply device 12 instead of the DC power supply device and a voltage having a predetermined strength is intermittently applied between the cathode electrode 2 and the anode electrode 3, the bundle structure of the carbon fibers 9 is obtained. Can be solved more effectively.

  The carbon layer 8 laminated on the cathode electrode 2 is, for example, a paste in which carbon fibers 9 are dispersed in a highly volatile solvent such as ethanol or acetone, or a terpionol solution in which an organic binder such as ethyl cellulose is dissolved. Is applied to the cathode conductor layer 7 and then heat-treated to remove the solvent or organic binder. In this state, the carbon fibers 9 in the carbon layer 8 are formed by van der Waals force. Aggregates to form a bundle structure, that is, a bundle structure, and is buried in the carbon layer 8. In addition, the direction of the carbon fibers 9 forming the bundle structure is indefinite, and most of the carbon fibers 9 are not directed toward the anode electrode 3. Therefore, in this state, the direction of electrons emitted from the cathode electrode 2 is not determined, and most of the electrons emitted from the cathode electrode 2 do not go to the anode electrode 3 (see FIG. 2A).

  Therefore, as shown in FIG. 2B, when a reverse bias voltage is applied between the cathode electrode 2 and the anode electrode 3 of the carbon fiber orientation device 1, an electric field from the cathode electrode 2 toward the anode electrode 3 is generated. The carbon fibers 9 in the cathode electrode 2 receive a force from the electric field and are aligned in a direction toward the anode electrode 3 (a direction perpendicular to the cathode electrode 2) in a state where a bundle structure is formed. The magnitude of the reverse bias voltage is an electric field that is 120% to 150% of an electric field (threshold electric field) necessary for applying a forward bias voltage to the cathode electrode 2 and the anode electrode 3 to emit electrons from the cathode electrode 2. The size is selected so that an electric field of approximately several kV / mm is generated.

  Further, when a reverse bias voltage is applied between the cathode electrode 2 and the anode electrode 3 of the carbon fiber aligning device 1, all the carbon fibers 9 of the cathode electrode 2 are positively charged. 9 are repulsive to each other. Therefore, a repulsive force acts only on the cathode electrode 2 in a horizontal direction on the bundled carbon fibers 9 aligned in a direction perpendicular to the cathode electrode 2, and this repulsive force is generated by van der Waals force acting on the carbon fibers 9. Therefore, the bundle structure of the carbon fibers 9 is eliminated, and the carbon fibers 9 can be sufficiently dispersed on the cathode electrode 2 as shown in FIG.

  When the carbon fiber 9 is sufficiently dispersed on the cathode electrode 2, the switch 13 is opened and the application of the reverse bias voltage is stopped. Even after the application of the reverse bias voltage is stopped, since all the carbon fibers 9 in the cathode electrode 2 are positively charged, mutual repulsion occurs. Therefore, even after the application of the reverse bias voltage is stopped, the dispersion state of the carbon fibers 9 on the cathode electrode 2 is maintained (see FIG. 2D).

  The carbon fiber orientation method according to the present embodiment is a method of aligning the carbon fibers contained in the cathode electrode vertically toward the anode electrode, so that it can be applied to a method of manufacturing carbon fibers dispersed on the cathode electrode. Yes.

  FIG. 3 is a view showing electron micrographs showing the state of the carbon fibers 9 in the cathode electrode 2 before and after the treatment by the carbon fiber orientation device 1, and FIG. 3 (a) shows the state before the treatment. 3 (b) shows the state after processing.

  According to FIG. 3, the carbon fibers 9 (see FIG. 3A) aggregated and buried in the cathode electrode 2 before the treatment are sufficiently dispersed on the upper surface of the cathode electrode 2 after the treatment. I understand that

  In addition, the structure of the carbon fiber orientation apparatus 1 is not limited to what was shown by this embodiment. For example, as shown in FIG. 4, if a heating device 16 is provided below the cathode electrode 2 to heat the cathode electrode 2, the polarization of the carbon fibers 9 is reduced and the carbon fibers 9 interact with each other. Therefore, the bundle structure of the carbon fibers 9 can be eliminated more efficiently, and the carbon fibers 9 can be sufficiently dispersed on the cathode electrode 2.

It is a notional block diagram of the carbon fiber orientation device which shows the embodiment of the present invention. It is a figure explaining the effect | action of a carbon fiber orientation apparatus. It is a figure showing the electron micrograph which shows the state of the carbon fiber in a cathode electrode before and behind the process by a carbon fiber orientation apparatus. It is a notional block diagram which shows the modification of a carbon fiber orientation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carbon fiber orientation apparatus 2 Cathode electrode 3 Anode electrode 4 Voltage application means 5 Casing 6 Cathode substrate 7 Cathode conductor layer 8 Carbon layer 9 Carbon fiber 10 Anode substrate 11 Anode conductor layer 12 Power supply device 13 Switch 14 Positive electrode 15 Negative electrode 16 Heating device

Claims (10)

Preparing a cathode electrode containing carbon fiber and an anode electrode disposed opposite to the cathode electrode;
A carbon fiber alignment method, wherein a reverse bias voltage is applied between the cathode electrode and the anode electrode. The method for aligning carbon fibers according to claim 1, wherein the direction of the tip of the carbon fibers in the cathode electrode is aligned with the direction toward the anode electrode. The carbon fiber alignment method according to claim 1 or 2, wherein the reverse bias voltage is applied under vacuum. The carbon fiber orientation method according to any one of claims 1 to 3, wherein the cathode electrode is heated. A cathode electrode containing carbon fiber, and an anode electrode disposed opposite to the cathode electrode,
A carbon fiber aligning apparatus comprising: a voltage applying unit that applies a reverse bias voltage between the cathode electrode and the anode electrode. The carbon fiber orientation device according to claim 5, wherein the voltage application unit is a DC power supply device that generates a DC voltage. 6. The carbon fiber orientation device according to claim 5, wherein the voltage applying means is a pulse voltage generator that generates a unipolar pulse voltage. The carbon fiber orientation device according to any one of claims 5 to 7, further comprising heating means for heating the cathode electrode. Preparing a cathode electrode containing carbon fiber and an anode electrode disposed opposite to the cathode electrode;
A reverse bias voltage is applied between the cathode electrode and the anode electrode. A method for producing carbon fibers dispersed on a cathode electrode. The method for producing carbon fibers dispersed on a cathode electrode according to claim 9, wherein the direction of the tip of the carbon fiber in the cathode electrode is aligned with the direction toward the anode electrode.

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