JP5463566B2 - Molded body and method for producing the same - Google Patents

Description

  The present invention relates to a molded body and a method for producing the same, and more particularly to a molded body having excellent strength and a method for producing the same.

  Fibrous carbon is known to have excellent electrical conductivity and mechanical strength. Among the fibrous carbons, carbon nanotubes and carbon nanofibers are expected to be future nanoelectronic materials because of their small fiber diameters.

  Fibrous carbon is classified into carbon nanotubes (fiber diameter of 1 to 10 nm), carbon nanofibers (fiber diameter of 10 to 1000 nm), and carbon fibers (fiber diameter of about 10 μm) depending on the fiber diameter. Among these, the carbon nanotube has a hollow cylindrical shape in which a granfen sheet in which carbon atoms are regularly arranged is rolled into a tube shape. When carbon nanotubes having such a shape are used as, for example, an electron emission source, electric field concentration tends to occur at the tip, and a high emission current density can be expected. In addition, since carbon nanotubes have high chemical and physical stability, they are expected to be stable against adsorption of residual gas and ion bombardment in an operating vacuum.

  In addition, a molded body formed from a plurality of carbon nanotubes and carbon nanofibers is considered to have excellent conductivity, and is expected as a functional material in the future.

  However, since the conventional molded body has carbon nanotubes or carbon nanofibers bonded together only by physical contact, it has been difficult to obtain practical strength.

  Accordingly, an object of the present invention is to provide a molded article excellent in strength and a method for producing the same.

  The present invention is a molded body containing a plurality of fibrous carbons bonded to each other and having a fiber diameter of 1 μm or less and Ga. According to the molded body according to the present invention, since a plurality of fibrous carbons are bonded to each other, the strength is excellent.

  In the molded body according to the present invention, the fibrous carbon is preferably a carbon nanotube or a carbon nanofiber. Usually, carbon nanotubes or carbon nanofibers have graphene defect ends on the surface. According to the molded body according to the present invention, a plurality of fibrous carbons are integrated by bonding the end portions of the graphene defects, so that the strength is excellent.

  The molded body according to the present invention is preferably formed in a sheet shape. Since it is formed in a sheet shape, it can be used for various applications.

  The method for producing a molded body according to the present invention includes a step of attaching Ga to each surface of a plurality of fibrous carbons having a fiber diameter of 1 μm or less, and a step of press-contacting the plurality of fibrous carbons to which Ga is attached. . According to the method for producing a molded body according to the present invention, Ga adheres to the graphene defect end portion on the surface of the fibrous carbon, and activates the graphene defect end portion. When a plurality of fibrous carbons whose graphene defect ends are activated are pressed together, the graphene defect ends on different fibrous carbon surfaces that come into contact with each other are bonded via Ga. As a result, a molded body having excellent strength can be obtained.

  In the present specification, “pressure contact” means that two substances are bonded by applying pressure in a state where the two substances are in close contact with each other.

  Preferably, in the method for producing a molded body according to the present invention, the step of attaching Ga to each surface of the plurality of fibrous carbons includes a step of bringing each surface of the fibrous carbons into contact with Ga vapor. Since Ga vapor is excellent in the bonding property with the graphene defect end portion on the surface of the fibrous carbon, gallium can be efficiently attached to the graphene defect end portion.

  Preferably, in the method for producing a molded body according to the present invention, the step of pressing the plurality of fibrous carbons includes a step of heating the surface of each of the plurality of fibrous carbons. By heating the surface of each of the plurality of fibrous carbons, the graphene defect ends on the different fibrous carbon surfaces that are in contact with each other can be efficiently bonded.

  Preferably, the method for producing a molded body according to the present invention further includes a step of heating each surface of the plurality of fibrous carbons after the step of pressing the plurality of fibrous carbons together. By heating the surface of each of the plurality of fibrous carbons, the graphene defect ends on the different fibrous carbon surfaces that are in contact with each other can be efficiently bonded.

  Preferably, in the method for producing a molded body according to the present invention, the step of heating the surface of each of the plurality of fibrous carbons includes a step of heating the plurality of fibrous carbons to 600 ° C. or higher. By heating a plurality of fibrous carbons to 600 ° C. or higher, graphene defect ends on different fibrous carbon surfaces that come into contact with each other can be efficiently bonded.

Preferably, in the method for producing a molded body according to the present invention, the step of pressing the plurality of fibrous carbons includes a step of applying a pressure of 1 × 10 ⁵ Pa or more to the plurality of fibrous carbons. By applying a pressure of 1 × 10 ⁵ Pa or more to a plurality of fibrous carbons, it is possible to efficiently bond the graphene defect ends on different fibrous carbon surfaces that come into contact with each other.

  According to the present invention, a molded product having excellent strength can be obtained.

(A) It is a schematic diagram which shows the molded object in embodiment of this invention. (B) It is a cross-sectional schematic diagram in line segment IB-IB of (a). It is a schematic diagram which shows the 1st process of the manufacturing method of the molded object in one embodiment of this invention. It is a schematic diagram which shows the 2nd process of the manufacturing method of the molded object in one embodiment of this invention. It is a schematic diagram which shows the 3rd process of the manufacturing method of the molded object in one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated.

<Molded body>
Fig.1 (a) is a schematic diagram which shows the molded object in embodiment of this invention. FIG. 1B is a schematic cross-sectional view taken along line IB-IB in FIG.

  As shown in FIG. 1 (a), a molded body 10 according to an embodiment of the present invention includes, for example, a plurality of fibrous carbons 1 bonded to each other, and, for example, a plurality of fibrous carbons being focused or laminated. It is integrated. Here, the term “bundling” means that a plurality of fibrous carbons 1 are gathered to form a bundle, and the term “stacking” means that the plurality of fibrous carbons 1 are stacked to form a layer.

  In FIG. 1A, the molded body 10 is formed into a sheet shape, but the shape is not particularly limited, and may be a corrugated sheet shape, a cylindrical shape, a tub shape, or the like. The thickness in the stacking direction of the fibrous carbon constituting the molded body is not particularly limited, but is preferably 10 to 1000 μm from the viewpoint of handling and moldability.

  With reference to FIG.1 (b), the fiber diameter d of each fibrous carbon 1 is 1 micrometer or less, and the Ga atom 2 has adhered to the surface.

<Fibrous carbon>
As the fibrous carbon 1 constituting the molded body 10 in one embodiment of the present invention, carbon nanotubes (fiber diameter 1 to 10 nm) or carbon nanofibers (fiber diameter 10 to 1000 nm) having a fiber diameter of 1 μm or less are used. Can do.

  As the carbon nanotube, a single wall nanotube (hereinafter abbreviated as “SWNT”) composed of a single-layer hexagonal network tube, or a multi-wall nanotube (hereinafter referred to as “SWNT”) composed of a multilayer hexagonal network tube (hereinafter referred to as “SWNT”). , Abbreviated as “MWNT”). In general, SWNT is more flexible, and tends to become more rigid as the number of layers increases like MWNT. SWNT and MWNT are desirably used properly according to the purpose in consideration of their properties.

  The applicable length of the fibrous carbon 1 is not particularly limited, but generally, a length in the range of 10 nm to 10000 μm is used, and a length in the range of 100 nm to 1000 μm is preferably used.

<Ga (gallium) atom>
The Ga atom 2 is attached to the surface of the fibrous carbon 1, and is considered to be particularly bonded to the graphene defect end portion on the surface of the fibrous carbon 1. Since Ga atoms in the molded body 10 are used as a catalyst for graphene bonding, it is preferable to limit the adhesion of Ga to the vicinity of the defect as much as possible and reduce the amount used as much as possible.

<Method for producing molded body>
The manufacturing method of the molded object 10 in one embodiment of this invention is demonstrated using FIGS. As shown in FIG. 3, the method for producing a molded body includes a step of attaching Ga to each surface of a plurality of fibrous carbons having a fiber diameter of 1 μm or less, and a plurality of fibrous forms having Ga attached thereto as shown in FIG. And a step of pressing the carbons together.

(Preparation of fibrous carbon)
Referring to FIG. 2, it is generally considered that fibrous carbon 1 has a graphene defect end 3 on the surface. At the graphene defect end, it can be estimated that carbon atoms are not bonded to each other and unpaired electrons remain in the graphene constituting the fibrous carbon as shown in the formula (1).

The fibrous carbon 1 is prepared in a dispersed state as much as possible.
(Step of attaching Ga to each surface of fibrous carbon)
Next, a step of attaching Ga atoms 2 to each surface of the fibrous carbon 1 (hereinafter also referred to as “Ga attachment step”) is performed.

  Referring to FIG. 3, the device 25 for depositing Ga includes a chamber 22, a heater 23, and a container 24. A heater 23 is provided on the outer wall of the chamber 22, and a container 24 is disposed inside the chamber 22. The container 24 is filled with liquid Ga20 heated by the heater 23. The heating temperature of the liquid Ga20 is preferably 600 to 2000 ° C. An evacuation system 22 a is provided on the left side of the chamber 22 in the drawing.

  The Ga adhesion step is performed by arranging a plurality of fibrous carbons 1 in the chamber 22 and bringing the surface of the fibrous carbon 1 into contact with Ga vapor 21 obtained by heating the liquid Ga20. Bulk Ga and carbon are non-solid solutions as a phase diagram. However, when the Ga vapor 21 is brought into contact with the fibrous carbon 1 on a micro scale, bonding occurs between the Ga atom 2 and the graphene defect end portion 3 on the surface of the fibrous carbon 1. As a result, for example, the graphene defect end 3 is activated as shown in Formula (2). The temperature of the fibrous carbon at this time is preferably 600 ° C. or less.

  The Ga adhesion step is performed by vaporizing an InGa alloy instead of liquid Ga. Moreover, it replaces with the above-mentioned method and is performed by immersing the some fibrous carbon 1 in liquid Ga.

  If the fibrous carbon 1 is dispersed, Ga can be more uniformly adhered to the fibrous carbon surface in the Ga adhesion step.

(Step of pressing a plurality of fibrous carbons to which Ga is attached)
Next, a step of press-contacting a plurality of fibrous carbons to which Ga is attached (hereinafter also referred to as “press-contact step”) is performed.

  Referring to FIG. 4, for example, a mold is filled with a plurality of fibrous carbons 1 and pressure is applied to the plurality of fibrous carbons 1. Thereby, the some fibrous carbon 1 couple | bonds together. This is presumed to be due to the following reason. When pressure is applied in a state where a plurality of fibrous carbons 1 are in close contact with each other, the graphene defect end portions 3 are directly bonded to each other as shown in, for example, the formula (3).

  As a result, the plurality of fibrous carbons 1 are integrated by converging or stacking to form a molded body 10. Since this molded object 10 is estimated that the some fibrous carbon 1 is couple | bonded by the covalent bond of carbon, it has the outstanding intensity | strength.

  In addition, you may heat the surface of each of several fibrous carbon simultaneously with performing the said press-contact process, or after the said press-contact process. Thereby, it is estimated that the bond between the graphene defect end portion 3 of the fibrous carbon 1 and the Ga atom 2 is released. Moreover, when heating each surface of the some fibrous carbon 1, it is preferable to heat several fibrous carbon to 600 degreeC or more, More preferably, it is 800-1100 degreeC. By heating the plurality of fibrous carbons to 600 ° C. or higher, the elimination of Ga atoms 2 is promoted, and the bonding between the graphene defect ends on the fibrous carbon surface is promoted.

In the pressure welding step, it is preferable to apply a pressure of 1 × 10 ⁵ Pa or more, preferably 1 × 10 ⁶ Pa or more to the plurality of fibrous carbons. By applying a pressure of 1 × 10 ⁵ Pa or more to a plurality of fibrous carbons, it is possible to efficiently bond the graphene defect ends on different fibrous carbon surfaces that come into contact with each other.

  For forming the formed body, a plurality of fibrous carbons are arranged in a mold having a desired shape such as a sheet shape or a corrugated sheet shape, and then a pressing process is performed.

<Example 1>
Carbon nanotubes dispersed as much as possible were prepared, which were subjected to treatment for removing the catalyst (iron, cobalt, nickel, etc.). The carbon nanotubes used in Example 1 have an average fiber diameter of 20 nm and an average fiber length of 100 μm.

Next, the carbon nanotube was placed in a heat treatment furnace. The heat treatment furnace was heated to 400 ° C. under a reduced pressure of 10 ⁻⁶ Torr, the liquid Ga in the crucible in the heat treatment furnace was vaporized to generate Ga vapor, and Ga was adhered to the carbon nanotube surface.

Thereafter, CNTs to which Ga was attached were laminated, and a sheet having a thickness of about 0.2 mm and a size of 5 mm × 20 mm square was formed. Thereafter, a pressure of 100 kgf / cm ² (98 × 10 ⁵ Pa) was applied to the sheet, and the temperature in the heat treatment furnace was increased to 1000 ° C., and then the sheet was cooled to room temperature while the pressure was applied.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The tensile strength at break of the molded body of Example 1 was 4 GPa.

<Example 2>
Carbon nanotubes dispersed as much as possible were prepared, which were subjected to treatment for removing the catalyst (iron, cobalt, nickel, etc.). The carbon nanotubes used in Example 2 have an average fiber diameter of 10 nm and an average fiber length of 200 μm.

Next, the carbon nanotube was placed in a heat treatment furnace. The heat treatment furnace was heated to 500 ° C. under a reduced pressure of 10 ⁻⁶ Torr, and the liquid Ga in the crucible in the heat treatment furnace was heated with an electron beam to generate Ga vapor, thereby attaching Ga to the carbon nanotube surface. .

Thereafter, CNTs to which Ga was attached were laminated, and a sheet having a thickness of about 0.5 mm and a size of 5 mm × 20 mm square was formed. Thereafter, a pressure of 10 kgf / cm ² (9.8 × 10 ⁵ Pa) was applied to the sheet and the temperature in the heat treatment furnace was raised to 900 ° C., and then the sheet was cooled to room temperature while the pressure was applied.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The tensile strength at break of the molded body of Example 2 was 4 GPa.

<Example 3>
Carbon nanotubes dispersed as much as possible were prepared, which were subjected to treatment for removing the catalyst (iron, cobalt, nickel, etc.). The carbon nanotubes used in Example 3 have an average fiber diameter of 30 nm and an average fiber length of 200 μm.

Next, the carbon nanotube was placed in a heat treatment furnace. The heat treatment furnace was heated to 600 ° C. under a reduced pressure of 10 ⁻⁶ Torr, the liquid Ga in the crucible in the heat treatment furnace was vaporized to generate Ga vapor, and Ga was adhered to the carbon nanotube surface.

Thereafter, CNTs to which Ga was attached were laminated to form a corrugated sheet having a thickness of about 1 mm. Thereafter, a pressure of 50 kgf / cm ² (49 × 10 ⁵ Pa) was applied to the sheet, and the temperature in the heat treatment furnace was raised to 800 ° C., and then the sheet was cooled to room temperature while the pressure was applied.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The tensile strength at break of the molded body of Example 3 was 3 GPa.

<Example 4>
Carbon nanotubes dispersed as much as possible were prepared, which were subjected to treatment for removing the catalyst (iron, cobalt, nickel, etc.). The carbon nanotubes used in Example 4 have an average fiber diameter of 10 nm and an average fiber length of 200 μm.

Next, the carbon nanotube was placed in a heat treatment furnace. The heat treatment furnace is heated to 450 ° C. under a reduced pressure of 10 ⁻⁶ Torr, and the GaIn alloy (Ga85In15) in the crucible in the heat treatment furnace is heated to 900 ° C. to vaporize the GaIn alloy, and the GaIn alloy is formed on the carbon nanotube surface. Attached.

Thereafter, CNTs to which a GaIn alloy was adhered were laminated, and a sheet having a thickness of about 0.5 mm and a size of 5 mm × 20 mm square was formed. Thereafter, a pressure of 100 kgf / cm ² (98 × 10 ⁵ Pa) was applied to the sheet, and the temperature in the heat treatment furnace was raised to 900 ° C., and then the sheet was cooled to room temperature while the pressure was applied.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The tensile strength at break of the molded body of Example 4 was 3 GPa.

<Example 5>
Carbon nanotubes dispersed as much as possible were prepared, which were subjected to treatment for removing the catalyst (iron, cobalt, nickel, etc.). The carbon nanotubes used in Example 5 have an average fiber diameter of 10 nm and an average fiber length of 500 μm.

Next, the carbon nanotube was placed in a heat treatment furnace. The heat treatment furnace was heated to 300 ° C. under a reduced pressure of 10 ⁻⁶ Torr, the liquid Ga in the crucible in the heat treatment furnace was vaporized to generate Ga vapor, and Ga was adhered to the carbon nanotube surface.

Thereafter, CNTs to which Ga was attached were laminated to form a sheet having a thickness of about 0.5 mm. Thereafter, a pressure of ⁵ kgf / cm ² (4.9 × 10 ⁵ Pa) was applied to the sheet, and the temperature in the heat treatment furnace was raised to 600 ° C., and then the sheet was cooled to room temperature while the pressure was applied.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The tensile strength at break of the molded body of Example 5 was 2 GPa.

<Comparative Example 1>
In Comparative Example 1, a molded body was prepared in the same process as in Example 1 except that liquid Ga was not used.

The tensile strength at break of the obtained sheet-like molded body was measured with a tensile tester.
The molded article of Comparative Example 1 had a tensile strength at break of 1 GPa.

  The production conditions and results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Fibrous carbon, 10 molded object, 2 Ga atom, 20 liquid Ga, 21 Ga vapor | steam, 22 chamber, 22a vacuum exhaust system, 23 heater, 24 container, apparatus for attaching 25 Ga, 3 graphene defect edge part.

Claims (9)

A plurality of fibrous carbon bonded to each other following a fiber diameter 1 [mu] m, and a Ga atom seen including,
The fibrous carbon is a carbon nanotube or a carbon nanofiber,
The molded body in which the plurality of fibrous carbons are bonded by a covalent bond of carbon . The molded object according to claim 1, which has a sheet-like shape. Attaching Ga atoms to the surface of each of a plurality of fibrous carbons having a fiber diameter of 1 μm or less;
Look including the step of pressing a plurality of fibrous carbon together with attached the Ga atom,
The step of attaching Ga atoms to the surface of each of the plurality of fibrous carbons includes a step of bringing each surface of the fibrous carbon into contact with Ga vapor or InGa vapor . The step of attaching Ga atoms to the surface of each of the plurality of fibrous carbons is 10 ^-6 The manufacturing method of the molded object of Claim 3 including the process of heating liquid Ga or InGa alloy under the reduced pressure below Torr. The method for producing a molded body according to claim 4, wherein a heating temperature of the liquid Ga or InGa alloy is 600 to 2000 ° C. The method for producing a molded body according to any one of claims 3 to 5 , wherein the step of press-contacting the plurality of fibrous carbons includes a step of heating each surface of the plurality of fibrous carbons. The manufacturing of the molded body according to any one of claims 3 to 5 , further comprising a step of heating the surface of each of the plurality of fibrous carbons after the step of press-contacting the plurality of fibrous carbons. Method.   The method for manufacturing a molded body according to claim 6 or 7, wherein the step of heating the surface of each of the plurality of fibrous carbons includes a step of heating the plurality of fibrous carbons to 600 ° C or higher. The step of pressing said plurality of fibrous carbon each other, comprising the step of applying a pressure of 1 × 10 ⁵ Pa or more to the plurality of the fibrous carbon, the molded body according to any one of claims 3-8 Production method.

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