JP2002180372A - Carbon fiber coated with metal oxide and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a carbon fiber coated with a metal oxide, or the like, having characteristic mechanical properties of carbon fiber comprising high strength and high elastic modulus while maintaining the characteristic feature of metal oxide. SOLUTION: The carbon fiber, strand, or the like, coated with the metal oxide and having a tensile load at break of >=1.5 g and a tensile elongation of >=0.5% is produced by covering a carbon fiber having a diameter of 3-10 μm with 1-100 wt.% metal oxide based on the weight of the fiber. The metal oxide is deposited on the surface of the carbon fiber by immersing a carbon fiber having a diameter of 3-10 μm, a tensile load at break of >=1.5 g and a tensile elongation of >=0.5% in a solution of a metal oxide precursor and irradiating with microwave radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal oxide-coated carbon fiber, a strand thereof, a chopped fiber thereof, a metal oxide-coated carbon fiber tissue structure using the same, and a production method thereof. These are the mechanical properties such as excellent specific strength and specific elastic modulus of carbon fiber, the unique properties of metal oxide coated on the surface of carbon fiber,
For example, it has properties such as magnetism, magnetic permeability, and superconductivity.

[0002]

2. Description of the Related Art The technique of manufacturing a composite material by simply coating different kinds of materials such as plastics, ceramics, and metal on carbon fiber is a relatively basic technique, and it is difficult to manufacture them by a simple method. They are widely implemented and products are available because they can.

In recent years, as one of the developments in the performance and use of composite materials seen in the emergence of high-performance carbon fiber reinforced plastics and the like, a fiber material which is a reinforcing fiber is coated with a material having another function, and the characteristics of both materials are improved. Attempts have been made to develop high-performance fiber-reinforced plastics having both of these properties, and various composite reinforcing fibers are being developed.

[0004] Such a reinforced fiber not only has a use to make use of the high strength and elastic modulus of the reinforced fiber itself, but also has a function such as an electric property of a material coated on the surface of the reinforced fiber. .

On the other hand, among metal oxides, magnetic oxides are not only used for magnetic recording media such as magnetic tapes, but are also expected to be widely used in terms of conductivity, surface adsorption ability, and electromagnetic wave absorbing function. . In particular, due to the recent advanced development of information and communication equipment, various kinds of radio waves are circulating in the outside world, and in connection with this, electromagnetic interference that causes malfunctions of computers and control devices has become a major social problem.

In recent years, the development of materials that reflect or absorb such electromagnetic waves has been advanced. In particular, ferrite, which is a magnetic oxide, has high electromagnetic wave absorption in a wide frequency range of electromagnetic waves. The development of technology for manufacturing molded articles using the same is also underway.

A technique for coating a carbon material with a metal oxide is as follows.
It is known from Japanese Patent Application Laid-Open No. 10-208541. However, in the case of these conventional techniques, it is not possible to apply a certain amount of metal oxide to the surface of each carbon fiber firmly and uniformly, and to obtain a metal oxide-coated carbon fiber having excellent mechanical properties. It has not been manufactured yet.

Means for coating the surface of the carbon fiber with the metal oxide include a conventional method of sizing by mixing the metal oxide with a pasty substance such as a sizing agent, a method of plating with a precursor solution of the metal oxide, A method of coating by chemical vapor deposition such as CVD has been studied. However, none of these methods is sufficiently satisfactory in terms of the adhesion state of the metal oxide, cost reduction by continuity, purity and crystallinity of the metal oxide, and the like.

In addition, a technique has been reported in which, when a metal oxide is coated on the carbon fiber surface, the carbon fiber is treated at a high temperature of 400 ° C. or higher. In the case of this method, a high temperature is used, so that the manufacturing method becomes complicated and energy is wasted.
Further, when a metal oxide is coated at a high temperature as in the above technique, there is a problem of deterioration of fiber properties such as embrittlement of carbon fibers in the process.

[0010]

SUMMARY OF THE INVENTION The inventor of the present invention has proposed a method of imparting high strength and high modulus carbon fibers to carbon fibers in order to impart the functions of metal oxides such as magnetism, magnetic permeability and superconductivity to the carbon fibers. As a result of intensive studies on the development of a fiber coated and composited with a metal oxide using a simple process and without using excessive energy, the use of microwaves enabled uniform and high-strength carbon fibers without impairing their high strength and elastic modulus. That they can produce metal oxide-coated carbon fiber filaments, strands, chopped fibers, and woven fabrics and nonwoven fabrics using them, and have completed the present invention. It is.

Accordingly, it is an object of the present invention to provide a metal oxide-coated carbon fiber or the like which maintains the mechanical properties of a carbon fiber while maintaining the high strength and high modulus of elasticity while maintaining the properties of the metal oxide. Is to do. Another object of the present invention is to provide a simpler method for producing the above-mentioned metal oxide-coated carbon fiber or the like of the energy-saving type. Further objects of the present invention will be understood by the following description.

[0012]

The present invention for solving the above-mentioned problems is as described below.

[1] A carbon fiber having a diameter of 3 to 10 μm is coated with a metal oxide in an amount of 1 to 100% by mass based on the mass of the fiber, and has a tensile load of 1.5 g or more and a tensile elongation of 0%. Metal oxide-coated carbon fiber characterized by being at least 5%.

[2] A metal oxide-coated carbon fiber strand obtained by bundling 100 to 100,000 metal oxide-coated carbon fibers according to [1], wherein the strand has a tensile strength of 200 kgf / mm ^2. As described above, a metal oxide-coated carbon fiber strand having a tensile elastic modulus of 20 tonf / mm ² or more, or a chopped fiber obtained by cutting them into a length of 1 to 100 mm.

[3] The metal according to claim 2, wherein the strand sizing agent comprising water, oils, thermosetting resin or thermoplastic resin is contained in an amount of 1 to 10 wt% based on the mass of the metal oxide-coated carbon fiber. Oxide-coated carbon fiber strand or metal oxide-coated chopped fiber.

[4] A metal oxide-coated carbon fiber tissue structure comprising the metal oxide-coated carbon fiber strand or chopped fiber according to [2] or [3].

[5] The metal oxide-coated carbon fiber tissue structure according to [4], wherein the metal oxide-coated carbon fiber tissue structure is a woven fabric, a nonwoven fabric, a synthetic paper, or a felt.

[6] A carbon fiber having a diameter of 3 to 10 μm, a tensile load of 1.5 g or more, and a tensile elongation of 0.5% or more, or a strand produced using the carbon fiber,
A metal oxide-coated carbon fiber, a metal oxide-coated carbon fiber in which a chopped fiber or a structure is immersed in a precursor solution of a metal oxide and irradiated with microwaves to attach the metal oxide to the carbon fiber surface. A method for producing a strand, a metal oxide-coated chopped fiber or a metal oxide-coated carbon fiber structure.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As carbon fibers used as a raw material for producing the metal oxide-coated carbon fibers of the present invention, commercially available polymer fibers such as phenol resin, rayon and polyacrylonitrile, petroleum pitch, Any carbon fiber made from pitch-based fibers such as carbon-based pitch and liquid-crystal-based pitch can be used, and is not particularly limited. But,
From the viewpoint of ease of production and stability of the obtained quality,
A polyacrylonitrile fiber (polyacrylonitrile and polyacrylonitrile obtained by copolymerizing a monomer having a polar group) is mainly treated with an inert gas atmosphere at 1000 to 1000
Polyacrylonitrile-based carbon fibers produced by firing at 3000 ° C. are preferable as carbon fibers giving high strength and high elastic modulus. These carbon fibers and a method for producing the carbon fibers are well known.

The polyacrylonitrile-based carbon fiber used in the present invention has a filament single fiber diameter of 3 to 10 μm.
m, fiber specific gravity 1.6-2.0, tensile elongation 0.5%
As described above, the tensile elongation is preferably 1 to 3%, the tensile load is 1.5 g or more, and preferably the tensile load is 10 to 3%.
Those having a performance of 0 g are desirable.

The strands formed by focusing the acrylic carbon fiber filaments used At a present invention, the tensile strength of 200 kgf / mm ² or more, preferably a tensile strength of 300~1000kgf / mm ^2, hit the strands
A material having a tensile elasticity of 20 tonf / mm ² or more, preferably a tensile elasticity of 20 to 60 tonf / mm ² is desirable.

The carbon fiber has a functional group such as a carboxylic acid group or a hydroxyl group on its surface, and has a depth of 0.5 cm on the carbon fiber surface.
Those having a plurality of continuously connected wrinkles in the fiber length direction of μm or less are preferable. Since the carbon fiber having such a shape enhances the adhesion of the metal oxide, a metal oxide-coated carbon fiber having excellent mechanical properties can be obtained.

The metal oxide-coated carbon fiber of the present invention is desirably produced by a wet method.

In the case of the wet method, carbon fibers are mixed with metal alkoxide, metal chloride,
By immersing in a water-soluble alkoxide such as metal sulfide, metal nitrate, or metal acetate or a solution of salts in water or an organic solvent or a mixture thereof, and supplying and adsorbing metal ions or compounds on the carbon fiber surface, a heating oxidation reaction is performed. This is to form a metal oxide film such as a ferrite compound on the carbon fiber surface.

In general, it is preferable to use water as the solvent.

The metal ions to be dissolved in the precursor solution include Fe, Ni, Cr, Mn, Cu, Zn, Co, A
1, Si, Ti, Zr, Ga, Sn, V and the like. As a precursor solution, methyl alcohol, ethyl alcohol,
An organic solvent such as acetone may be contained. A small amount of acid or base may be included in the solution.

The metal ion concentration in the precursor solution is not particularly limited, but is preferably 10 M / L or less, particularly 0.1 to 1 M in order to uniformly coat the metal oxide on the carbon fiber surface.
/ L is preferred.

It is preferable that a basic compound such as ammonia or a urea-based compound coexist in the precursor solution.

The thermal oxidation reaction is a reaction in which the carbon fiber is immersed in the precursor solution and then heated to coat the surface of the carbon fiber with a metal oxide.

The thermal oxidation reaction is preferably performed by irradiating a microwave. By performing a heat treatment under normal pressure or under pressure while irradiating microwaves, the metal oxide can be coated on the carbon fibers.

The temperature of the precursor solution reached by microwave irradiation varies depending on the type and pressure of the solvent, but is preferably 400 ° C. or lower, particularly preferably 100 to 300 ° C. The heating rate to the maximum temperature is preferably 5 to 50 ° C./min.

The pressure is 2000 kPa or less, especially 500 to
1000 kPa is preferred. The medium to be pressurized is preferably an inert gas such as nitrogen or argon.

The reaction time is preferably 10 hours or less at the maximum temperature, usually 2 to 5 hours.

As an operation, a precursor solution of a metal oxide and carbon fibers are placed in a microwave-permeable reaction vessel, and the fibers themselves are heated by irradiating them with microwaves. As a result, the heated carbon fiber surface is uniformly coated with the metal oxide. Alternatively, while continuously supplying the carbon fiber and the precursor solution to the microwave-permeable reaction vessel from the outside, the microwave may be continuously irradiated to the reaction vessel. According to this method, continuous long-fiber metal oxide-coated carbon fibers can be produced as well as short fibrous metal oxide-coated carbon fibers. Teflon (registered trademark), quartz, and the like can be exemplified as the microwave-permeable material used for the reaction vessel.

Microwaves are electromagnetic waves having a frequency of 0.3 to 30 GHz. The frequency that can be generally used is determined to be 2.45 GHz by the Radio Law, but any microwave can be used for the above-mentioned thermal oxidation reaction.

The coating mass of the metal oxide with respect to the mass of the carbon fiber can be set arbitrarily. Preferably, the mass of the metal oxide is 1 g or less, particularly 0.02 to 0.5 g per 1 g of the carbon fiber.
g is preferred.

The metal oxide-coated carbon fiber produced by using the microwave has a metal oxide coating such as ferrite having high crystallinity on the fiber surface. When the microwave is irradiated on the carbon fiber immersed in the precursor solution, the surface of the carbon fiber can be heated to a high temperature of 200 ° C. or more in a short time, so that the crystallization of the metal oxide is thought to occur quickly.

When a precursor solution containing the metal salt or the like is used, the metal oxide finally coated on the carbon fibers is F
e, Ni, Cr, Mn, Cu, Zn, Co, Al, S
An oxide containing at least one or more metals such as i, Ti, Zr, Ga, Sn, and V is obtained.

Among the metal oxides, the magnetic oxide N
i ferrite, Mn ferrite, Zn ferrite, Co
Carbon fibers coated with ferrite compounds such as ferrite, ZnNi ferrite, ZnMn ferrite, and ZnCo ferrite exhibit an electromagnetic wave absorbing function and are industrially useful.

The obtained metal oxide-coated carbon fiber is
Maintains various physical property values of raw carbon fiber without lowering, and has high performance. That is, the obtained metal oxide-coated carbon fiber single fiber filament has a tensile load of 1.5 g or more and a tensile elongation of 0.5% or more, which is equivalent to the strength of the raw carbon fiber. Further, a strand obtained by bundling the above metal oxide-coated carbon fibers in a bundle of 100 to 100,000 has a tensile strength of 200 kgf / mm ² or more and a tensile elastic modulus of 2
0 tonf / mm ² or more.

The metal oxide-coated carbon fiber of the present invention can be subjected to a sizing agent treatment used for known reinforcing fibers in order to improve handleability.

As the sizing agent, any of commercially available inorganic or organic sizing agents can be used. In particular, an epoxy resin, a urethane resin, a polyester resin, a bismaleimide resin, an imide resin, an amide resin, and the like, which are sizing agents for carbon fibers, can be used alone or in combination of two or more. In particular, a sizing agent composed of an epoxy resin and a urethane resin alone or in combination of two or more types is preferable. Strands bundled with these resins have good spreadability and good spreadability during processing.

The amount of the sizing agent used is preferably 0.5 to 3.0% by mass based on the metal oxide-coated carbon fibers.

The metal oxide-coated carbon fiber is made of a single fiber filament of 100 to 10 in consideration of productivity improvement and physical properties.
If a total of 000 pieces are handled as one strand and the product is wound into a bobbin, it may be convenient in handling or the like. Depending on the application, the strand may be divided or, conversely, a plurality of strands may be entangled to form one strand, which may be wound on a bobbin to form a product.

The metal oxide-coated carbon fiber strand may be cut into short fibers having a length of 1 to 100 mm into chopped fibers. This may be made into a synthetic paper by papermaking by a general method, or may be kneaded with a matrix resin to form a molded article.

The metal fiber-coated carbon fiber strand obtained by the treatment with the sizing agent may be subjected to another sizing agent treatment to improve the sizing property, and then cut into short fibers for use.

Using a metal oxide-coated carbon fiber, a woven fabric,
A metal oxide-coated carbon fiber tissue structure such as a nonwoven fabric, a synthetic paper, or a felt can also be produced. In this case, structures having different structures and different basis weights can be manufactured using known manufacturing methods.

Further, a carbon fiber tissue structure is manufactured in advance using carbon fibers not coated with a metal oxide,
This may be subjected to microwave heating in a metal oxide precursor solution to produce a structure coated with a metal oxide such as ferrite.

The metal oxide-coated carbon fiber tissue structure such as woven fabric, nonwoven fabric, synthetic paper, and felt of the present invention has a low strength of less than 200 kgf / mm ² of tensile strength between the metal oxide-coated carbon fiber and the strand. Or a low modulus carbon fiber having a tensile modulus of less than 20 tonf / mm ² . In addition to the carbon fibers, the following reinforcing fibers can be used in combination with the metal oxide-coated carbon fibers. Other reinforcing fibers may be any of inorganic and organic fibers, and include natural fibers, synthetic polymer fibers, glass fibers, aromatic aramid fibers, aromatic polyamide fibers, boron fibers, alumina fibers, and silicon carbide. Fibers and the like can be exemplified.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[0051]

EXAMPLE 1 A 500 ml cylindrical Teflon container was charged with FeCl ₃ .6.
The concentration of H ₂ O is 0.2 M / L, and the concentration of urea is 0.8 M / L.
L, 300 ml of an aqueous solution having a cobalt concentration of Co: Fe = 1: 5 (molar ratio) was added. Further, 1.0 g of carbon fiber (Vesfite HTA-12K, diameter of 7 μm, tensile load of single fiber of 15 g, tensile elongation of 1.5%) was immersed in the aqueous solution, and the inside of the Teflon container was degassed by reducing the pressure. . After placing the Teflon container in a stainless steel autoclave reactor, the inside of the autoclave was purged with nitrogen gas for 10 minutes.
The pressure was increased to 00 kPa. The reactor was irradiated with microwaves and heated to 200 ° C. at a heating rate of 20 ° C./min.
C. for 1 hour. Thereafter, the microwave irradiation was stopped and cooling was performed. When the temperature reached 50 ° C., the pressure was returned to normal pressure.

The autoclave was opened, and the Teflon container was taken out. The carbon fiber and the aqueous solution were separated by mesh filtration, and the carbon fiber was washed with distilled water. The surface of the carbon fiber dried at 105 ° C. for 2 hours turned brown and showed magnetism that reacted to a magnet.

The obtained fiber was subjected to a scanning electron microscope (SE).
M). A substance considered to be a uniform metal oxide with a thickness of about 1 μm adhered to the carbon fiber surface. Wide-angle X-ray diffraction and metal analysis of the substance formed on the carbon fiber surface confirmed that this substance was a magnetic oxide of CoFe. The attached amount of the magnetic oxide calculated from the change in the mass of the carbon fiber before and after the treatment was 5.0 mass% based on the mass of the carbon fiber (100 mass%).

This magnetic carbon fiber-coated carbon fiber has a tensile load of a single fiber of 13 g, a tensile elongation of 1.0%, and a strand composed of 12,000 filaments has a tensile strength of 350 kgf / mm ² , and the tensile modulus was 26 tonf / mm ² .

This CoFe magnetic carbon fiber-coated carbon fiber was finely pulverized (average length: 0.5 mm) and mixed with an epoxy resin in an amount of 30% by mass to produce a 2.0 mm-thick flat molded product. When the electromagnetic wave absorption characteristics of the molded body were evaluated,
It became 10 dB at a frequency of 800 MHz, and the electromagnetic wave absorption characteristics were confirmed.

Comparative Example 1 The carbon fiber (Vesfite HTA-1) used in Example 1 was used.
2K) was finely pulverized without coating with ferrite, and mixed with a resin in the same manner as in Example 1 to produce a molded article. When the electromagnetic wave absorption characteristics of the molded body were evaluated, it was 5 dB at a frequency of 800 MHz. Although there was electromagnetic wave absorption characteristics, the absorption characteristics were inferior to those of Example 1.

Example 2 A 500 ml cylindrical Teflon container was charged with FeCl ₃ .6.
The concentration of H ₂ O is 0.2 M / L, and the concentration of urea is 0.8 M / L.
L, an aqueous solution having a nickel chloride concentration of 0.1 M / L
0 ml was added. Further, 1.0 g of carbon fiber (Vesfight HTA-12K, diameter 7 μm, tensile load 1 of single fiber)
(5 g, tensile elongation 1.5%) was immersed in an aqueous solution, and the inside of the Teflon container was degassed by reducing the pressure. After placing the Teflon container in a stainless steel autoclave reactor, the inside of the autoclave was pressurized to 500 kPa with nitrogen gas. The reactor was irradiated with microwaves, heated to 200 ° C. at a heating rate of 20 ° C./min, and kept at 200 ° C. for 1 hour. After that, the microwave irradiation was stopped and cooling was performed.
When the temperature reached 0 ° C., the pressure was returned to normal pressure.

The autoclave was opened, and the Teflon container was taken out. The carbon fiber and the aqueous solution were separated by mesh filtration, and the carbon fiber was washed with distilled water. The surface of the carbon fiber dried at 105 ° C. for 2 hours turned brown and showed magnetism that reacted to a magnet.

The obtained fiber was subjected to a scanning electron microscope (SE).
M). A substance considered to be a uniform metal oxide with a thickness of about 1 μm adhered to the carbon fiber surface. Wide-angle X-ray diffraction and metal analysis of the substance formed on the carbon fiber surface confirmed that this substance was a magnetic oxide of NiFe. The attached amount of the magnetic oxide calculated from the change in the mass of the carbon fiber before and after the treatment was 5.0 mass% based on the mass of the carbon fiber (100 mass%).

This magnetic carbon fiber-coated carbon fiber has a tensile load of a single fiber of 12 g, a tensile elongation of 1.2%, and a strand composed of 12,000 filaments having a tensile strength of 340 kgf / mm ² , and the tensile modulus was 25 tonf / mm ² .

The NiFe magnetic carbon fiber-coated carbon fiber was finely pulverized (average length: 0.5 mm) and mixed with an epoxy resin in an amount of 50% by mass to produce a 2.0 mm-thick flat molded product. When the electromagnetic wave absorption characteristics of the molded body were evaluated,
It became 20 dB at a frequency of 800 MHz, and the electromagnetic wave absorption characteristics were confirmed.

Example 3 1 g of commercially available carbon fiber (Vesfite HTA-6K) was sampled, immersed in 50 ml of a 50% by mass aqueous solution of titanium sulfate, and 50% aqueous ammonia was gradually added until the pH reached 7. The carbon fiber was taken out from the porridge solution, washed with water, dried, and dried at 540 ° C. for 3 hours. The color of the fiber was almost unchanged and was black.

It was confirmed by wide-angle X-ray diffraction and scanning electron microscopy that the fiber surface was coated with titanium oxide. From the weight change before and after the treatment, the coating amount was about 5% by mass. all right.

The titanium oxide-coated carbon fiber has a single fiber tensile load of 20 g, a tensile elongation of 0.8%, and a strand composed of 6,000 filaments having a tensile strength of 420 kgf / mm. ^{2. The} tensile modulus was 24 tonf / mm ² .

To evaluate the thermal oxidation resistance of the fiber, the weight change after the fiber was treated at 500 ° C. for 3 hours in air was measured, and the weight change before and after the treatment was 3%.
The weight change of the same carbon fiber under the same conditions as before the coating with titanium oxide was 10%, and improvement in heat-resistant oxidation resistance by the coating of titanium oxide was recognized.

[0066]

The metal oxide-coated carbon fiber of the present invention has both the characteristics of the metal oxide and the characteristics of the carbon fiber. There is no. That is, the mechanical strength and the like are the same as those originally possessed by the carbon fiber, and the characteristics of the metal oxide are maintained. Therefore, when the metal oxide is a ferrite-based magnetic material, the metal oxide-coated carbon fiber of the present invention coated with the ferrite magnetic material can exhibit a high radio wave absorption function and the like. In particular, when a tissue structure is formed using the metal oxide-coated carbon fiber of the present invention, a structure having high strength can be obtained, which is useful.

In the production method of the present invention, since the heat oxidation treatment is carried out by using microwaves, the metal oxide-coated carbon fiber can be produced easily in a relatively short time, and is preferable as an energy-saving production method. Things.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D03D 15/12 D06B 19/00 B 4L048 D06B 19/00 D06M 10/00 A 4L055 D06M 10/00 15/55 15/55 D21H 13/50 D21H 13/50 D06M 101: 40 // D06M 101: 40 11/12 (72) Inventor Yoshinori Suzuki 234 Kamidogari, Nagaizumi-cho, Sunto-gun, Shizuoka Pref. Toho Rayon Co., Ltd. (72) Inventor Shunsaku Kato 2217-43 Hayashi-cho, Takamatsu-shi, Kagawa Prefecture Kagawa Prefectural Industrial Technology Promotion Institute Research Institute Attached to High-Temperature High-Pressure Fluid Research Institute (72) F-term (reference) in Laboratory for High Temperature and High Pressure Fluid Technology, attached to Kawaken Industrial Technology Promotion Foundation 3B154 AA14 AB03 AB09 AB20 AB22 AB23 BA60 BB12 BB2 2 BB32 BD17 BD20 BE04 BF06 BF10 BF18 DA06 DA30 4L031 AA27 AB01 BA09 BA33 CB03 DA15 4L033 AA09 AB01 AC11 AC12 CA45 CA49 CA50 CA55 DA06 4L036 MA04 MA33 MA35 PA17 PA26 RA24 UA06 UA25 4L037 AT02 FA05 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 A03 AA49 AA52 AA56 CA00 CA01 CA05 4L055 AF03 AF44 AF47 EA01 EA16 FA13 FA30 GA01 GA03

Claims (6)

[Claims] A carbon fiber having a diameter of 3 to 10 μm is coated with a metal oxide in an amount of 1 to 100% by mass based on the mass of the fiber, and has a tensile load of 1.5 g or more and a tensile elongation of 0.1%. A metal oxide-coated carbon fiber having a content of 5% or more. 2. A metal oxide-coated carbon fiber strand obtained by bundling 100 to 100,000 metal oxide-coated carbon fibers according to claim 1, wherein the strand has a tensile strength of 200 kgf / mm ² or more. And metal oxide-coated carbon fiber strands having a tensile elastic modulus of 20 tonf / mm ² or more, or chopped fibers obtained by cutting them into a length of 1 to 100 mm. 3. The metal oxide according to claim 2, wherein the strand sizing agent comprising water, oils, thermosetting resin, or thermoplastic resin is contained in an amount of 1 to 10% by weight based on the mass of the metal oxide-coated carbon fiber. Object coated carbon fiber strand or metal oxide coated chopped fiber. 4. A metal oxide-coated carbon fiber tissue structure comprising the metal oxide-coated carbon fiber strand according to claim 2 or 3, or a chopped fiber. 5. The metal oxide-coated carbon fiber tissue structure,
The metal oxide-coated carbon fiber tissue structure according to claim 4, which is a woven fabric, a nonwoven fabric, a synthetic paper, or a felt. 6. A carbon fiber having a diameter of 3 to 10 μm, a tensile load of 1.5 g or more, and a tensile elongation of 0.5% or more, or a strand, chopped fiber or structure manufactured using the carbon fiber, A metal oxide-coated carbon fiber, a metal oxide-coated carbon fiber strand, a metal oxide-coated chopped fiber, which is immersed in a precursor solution of the metal oxide and irradiated with microwaves to attach the metal oxide to the carbon fiber surface. Alternatively, a method for producing a metal oxide-coated carbon fiber structure.