JPWO2016203746A1 - Conductive nonwoven fabric and method for producing the same - Google Patents

Abstract

An object of this invention is to provide the electroconductive nonwoven fabric excellent in electroconductivity. The conductive nonwoven fabric of the present invention includes fibrous carbon nanostructures such as carbon nanotubes and conductive fibers such as carbon fibers. Moreover, the manufacturing method of the conductive nonwoven fabric of this invention includes the process of removing a dispersion medium from the dispersion liquid containing fibrous carbon nanostructure, a conductive fiber, and a dispersion medium, and forming a conductive nonwoven fabric.

Description

  The present invention relates to a conductive nonwoven fabric and a method for producing a conductive nonwoven fabric.

  Conventionally, as a sheet-like conductive member, a nonwoven fabric (conductive nonwoven fabric) formed using a fibrous conductive material has been used. And as a conductive nonwoven fabric, the nonwoven fabric excellent in electroconductivity and mechanical characteristics is calculated | required.

  Thus, for example, in Patent Document 1, carbon nanotubes (hereinafter sometimes referred to as “CNT”) that are attracting attention as materials having excellent electrical conductivity and mechanical properties are aggregated in a sheet shape, thereby providing electrical conductivity and mechanical properties. A technique for providing a nonwoven fabric having excellent mechanical properties has been proposed.

JP 2010-105909 A

  However, the conventional conductive nonwoven fabric formed using only carbon nanotubes has been required to further improve conductivity.

  Then, an object of this invention is to provide the electroconductive nonwoven fabric excellent in electroconductivity.

  The inventor has intensively studied to achieve the above object. And this inventor does not form a nonwoven fabric only using fibrous carbon nanostructures, such as a carbon nanotube considered to be especially excellent in electroconductivity, but fibrous carbon nanostructure and fiber Surprisingly, it was found that forming a non-woven fabric using a mixture with conductive fibers having a larger fiber diameter than the carbon-like carbon nanostructure yields a conductive non-woven fabric that is extremely excellent in electrical conductivity. It was.

That is, this invention aims at solving the said subject advantageously, The conductive nonwoven fabric of this invention is characterized by including a fibrous carbon nanostructure and a conductive fiber. Thus, if a fibrous carbon nanostructure and a conductive fiber are used, a conductive nonwoven fabric excellent in conductivity can be obtained.
In the present invention, the “fibrous carbon nanostructure” refers to a fibrous carbon structure having an outer diameter (fiber diameter) of less than 1 μm. In the present invention, “fiber” refers to a fibrous material having a fiber diameter of 1 μm or more, and “fiber” does not include “fibrous carbon nanostructure”.

  Here, the conductive nonwoven fabric of the present invention preferably contains the conductive fiber at a ratio of 5 parts by mass or more and 4000 parts by mass or less per 100 parts by mass of the fibrous carbon nanostructure. This is because if the conductive fiber content is 5 parts by mass or more and 4000 parts by mass or less per 100 parts by mass of the fibrous carbon nanostructure, the conductivity of the conductive nonwoven fabric can be further improved.

In the conductive nonwoven fabric of the present invention, the fibrous carbon nanostructure preferably has a BET specific surface area of 600 m ² / g or less. When the BET specific surface area of the fibrous carbon nanostructure is 600 m ² / g or less, the effect of improving the conductivity obtained by forming the conductive nonwoven fabric using the fibrous carbon nanostructure and the conductive fiber is particularly effective. Because it is big.
In the present invention, the “BET specific surface area” refers to a nitrogen adsorption specific surface area measured using the BET method.

In the conductive nonwoven fabric of the present invention, a fibrous carbon nanostructure containing carbon nanotubes can be used as the fibrous carbon nanostructure.
Furthermore, in the conductive nonwoven fabric of the present invention, conductive fibers containing carbon fibers can be used as the conductive fibers.

  Moreover, this invention aims at solving the said subject advantageously, The manufacturing method of the conductive nonwoven fabric of this invention is a method of manufacturing either of the conductive nonwoven fabric mentioned above, Comprising: It is preferable to include a step of forming a conductive nonwoven fabric by removing the dispersion medium from a dispersion liquid including a carbon-like carbon nanostructure, conductive fibers, and a dispersion medium. Thus, if a dispersion medium is removed from a dispersion liquid containing fibrous carbon nanostructures, conductive fibers, and a dispersion medium to form a conductive nonwoven fabric, a conductive nonwoven fabric excellent in conductivity can be easily obtained. It is done.

And the manufacturing method of the electroconductive nonwoven fabric of this invention pumps the rough dispersion liquid formed by adding the said fibrous carbon nanostructure in the said dispersion medium to a capillary channel by the pressure of 60 MPa or more and 200 MPa or less, After applying a shearing force to the coarse dispersion liquid to obtain a fibrous carbon nanostructure dispersion liquid having an average particle size of 60 μm or less, the conductive fibers are mixed with the fibrous carbon nanostructure dispersion liquid to obtain the dispersion liquid. It is preferable to further include a step of preparing Thus, if a dispersion liquid is prepared by mixing the fibrous carbon nanostructure dispersion liquid obtained by applying shear force to the coarse dispersion liquid, the fibrous carbon nanostructure body and the conductive fibers are good. A dispersion liquid dispersed in is obtained. Therefore, if a conductive nonwoven fabric is formed using the dispersion, the conductivity of the conductive nonwoven fabric can be further improved.
In the present invention, the “average particle diameter” of the fibrous carbon nanostructure dispersion refers to the median diameter (volume conversion value) of the solid contained in the fibrous carbon nanostructure dispersion, It can be measured using a particle size distribution meter.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive nonwoven fabric excellent in electroconductivity can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the conductive nonwoven fabric of the present invention includes fibrous carbon nanostructures and conductive fibers. And the conductive nonwoven fabric of this invention can be manufactured, for example using the manufacturing method of the conductive nonwoven fabric of this invention.

(Conductive non-woven fabric)
The conductive nonwoven fabric of the present invention is usually a nonwoven fabric formed by assembling a plurality of fibrous carbon nanostructures and a plurality of conductive fibers into a sheet shape. In addition to the fibrous carbon nanostructure and the conductive fiber, the conductive nonwoven fabric may contain other components such as an additive used during the production of the conductive nonwoven fabric.
And since the conductive nonwoven fabric of this invention contains both the fibrous carbon nanostructure and conductive fiber, it exhibits the outstanding electroconductivity.

  Here, the reason why a conductive nonwoven fabric excellent in conductivity can be obtained by using fibrous carbon nanostructures and conductive fibers is not clear, but the fibrous carbon nanostructures having different fiber diameters and conductivity are not clear. It is inferred that the formation of the nonwoven fabric by intertwining with the fibers makes it possible to form a conductive path in the nonwoven fabric better than when the nonwoven fabric is formed using only one of them.

<Fibrous carbon nanostructure>
The fibrous carbon nanostructure constituting the conductive nonwoven fabric is not particularly limited, and a fibrous carbon nanostructure having conductivity can be used. Specifically, as the fibrous carbon nanostructure, for example, a carbon nanostructure having a cylindrical shape such as a carbon nanotube (CNT), or a carbon nanostructure in which a carbon six-membered ring network is formed in a flat cylindrical shape. A non-cylindrical carbon nanostructure such as a body can be used. These may be used individually by 1 type and may use 2 or more types together.

  And among the above-mentioned, as a fibrous carbon nanostructure, it is more preferable to use the fibrous carbon nanostructure containing CNT. This is because if the fibrous carbon nanostructure containing CNT is used, the conductivity of the conductive nonwoven fabric can be further improved.

Here, the fibrous carbon nanostructure containing CNT may be composed of only CNT, or may be a mixture of CNT and fibrous carbon nanostructure other than CNT.
The CNT in the fibrous carbon nanostructure is not particularly limited, and single-walled carbon nanotubes and / or multi-walled carbon nanotubes can be used. Preferably, it is a single-walled carbon nanotube. This is because the smaller the number of carbon nanotube layers, the better the conductivity of the conductive nonwoven fabric.

In addition, the fibrous carbon nanostructure containing CNT is not particularly limited, and is manufactured using a known CNT synthesis method such as an arc discharge method, a laser ablation method, a chemical vapor deposition method (CVD method), or the like. can do. Specifically, a fibrous carbon nanostructure containing CNTs, for example, supplies a raw material compound and a carrier gas onto a substrate having a catalyst layer for producing carbon nanotubes on the surface, and chemical vapor deposition (CVD) Method), when a CNT is synthesized by a method, the catalyst activity of the catalyst layer is dramatically improved by making a small amount of oxidizing agent (catalyst activating substance) present in the system (super growth method; International Publication No. 2006). / 011655), and can be produced efficiently. Hereinafter, the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.
And the fibrous carbon nanostructure containing CNT manufactured by the super growth method may be comprised only from SGCNT, and in addition to SGCNT, other carbon nanostructures, such as a non-cylindrical carbon nanostructure, for example A structure may be included.

The average diameter of the fibrous carbon nanostructure is preferably 0.5 nm or more, more preferably 1 nm or more, preferably 15 nm or less, and more preferably 10 nm or less. If the average diameter of the fibrous carbon nanostructure is 0.5 nm or more, it is possible to suppress the aggregation of the fibrous carbon nanostructure and form a conductive nonwoven fabric that is homogeneous and excellent in conductivity. Moreover, if the average diameter of fibrous carbon nanostructure is 15 nm or less, the electroconductivity of a conductive nonwoven fabric can be improved.
In the present invention, the average diameter of fibrous carbon nanostructures can be determined by measuring the diameter (outer diameter) of 100 fibrous carbon nanostructures selected at random using a transmission electron microscope. it can. Moreover, the average diameter of the fibrous carbon nanostructure may be adjusted by changing the production method and production conditions of the fibrous carbon nanostructure, or the fibrous carbon nanostructure obtained by a different production method may be used. You may adjust by combining multiple types.

  Furthermore, in the fibrous carbon nanostructure, the average length of the structure at the time of synthesis is preferably 1 μm or more, more preferably 100 μm or more, and preferably 5000 μm or less. If average length is 1 micrometer or more, the conductive nonwoven fabric excellent in electroconductivity can be formed favorably. Note that the longer the structure length during synthesis, the more easily the fibrous carbon nanostructure is damaged during the process of forming the conductive nonwoven fabric. Is preferably 5000 μm or less.

Further, from the viewpoint of obtaining a conductive non-woven fabric with high conductivity, the fibrous carbon nanostructure preferably has a BET specific surface area of 200 m ² / g or more, more preferably 800 m ² / g or more. It is preferably 2500 m ² / g or less, and more preferably 1200 m ² / g or less. When the BET specific surface area of the fibrous carbon nanostructure is 200 m ² / g or more, the conductivity of the conductive nonwoven fabric can be sufficiently increased. In addition, if the BET specific surface area of the fibrous carbon nanostructure is 2500 m ² / g or less, the aggregation of the fibrous carbon nanostructure can be suppressed, and a conductive nonwoven fabric excellent in conductivity can be formed. .

On the other hand, the conductive nonwoven fabric is formed using only the fibrous carbon nanostructure by forming the conductive nonwoven fabric using both the fibrous carbon nanostructure and the conductive fiber. From the viewpoint of sufficiently obtaining the effect of improving the conductivity (hereinafter, sometimes referred to as “conductivity improvement effect”), the fibrous carbon nanostructure has a BET specific surface area of 600 m ² / g or less. It is preferably 400 m ² / g or less.
In general, fibrous carbon nanostructures having a small BET specific surface area are unlikely to be entangled with each other, and it is considered difficult to form a nonwoven fabric excellent in self-supporting property by using only a fibrous carbon nanostructure having a small BET specific surface area. However, if both fibrous carbon nanostructures and conductive fibers are used, even when fibrous carbon nanostructures having a small BET specific surface area are used, a conductive nonwoven fabric excellent in self-supporting properties can be easily obtained. Can be formed.

<Conductive fiber>
The conductive fiber constituting the conductive nonwoven fabric is not particularly limited, and a known fiber having conductivity can be used. Specifically, as the conductive fiber, for example, a metal fiber or a carbon fiber can be used. In addition, as the conductive fiber, a metal-coated fiber formed by coating the surface of a fibrous material such as carbon fiber, resin fiber, and glass fiber with a metal can also be used. In addition, as a metal which coat | covers the surface of a fibrous material, nickel, ytterbium, gold | metal | money, silver, copper etc. are mentioned, for example. In addition, as a method of coating the surface of the fibrous material with metal, for example, a plating method, a CVD method, a PVD method, an ion plating method, a vapor deposition method, or the like can be used. Alternatively, two or more kinds may be used in combination.

  Among the above-described conductive fibers, carbon fibers such as PAN-based carbon fibers, pitch-based carbon fibers, and graphite fibers are preferably used, and pitch-based carbon fibers or graphite fibers are more preferably used. More preferably, carbon fiber is used.

  In general, conductive fibers such as carbon fibers are considered to have lower conductivity than fibrous carbon nanostructures such as carbon nanotubes. However, the conductive nonwoven fabric formed using the fibrous carbon nanostructure and the conductive fiber is surprisingly a fibrous carbon nanostructure and a conductive material having lower conductivity than the fibrous carbon nanostructure. Even when a conductive fiber is used, it is possible to exhibit conductivity superior to that of a conductive nonwoven fabric formed using only fibrous carbon nanostructures. The reason for this is not clear, but it is presumed that the conductive carbon nanostructure and the conductive fiber are intertwined well so that a conductive path is formed well in the nonwoven fabric.

Here, the average fiber diameter of the conductive fibers is preferably 3 μm or more, more preferably 5 μm or more, preferably 50 μm or less, and more preferably 25 μm or less. When the average fiber diameter of the conductive fibers is within the above range, the conductivity of the conductive nonwoven fabric can be further improved.
In the present invention, the average fiber diameter of the conductive fibers can be determined by measuring the fiber diameter of 100 conductive fibers selected at random using a scanning electron microscope.

  In addition, the average fiber diameter of the conductive fibers is preferably 100 to 5000 times the average diameter of the fibrous carbon nanostructure, and more preferably 100 to 1000 times. If the average fiber diameter of the conductive fiber is 100 times or more and 5000 times or less than the average diameter of the fibrous carbon nanostructure, the fibrous carbon nanostructure and the conductive fiber are entangled well, and the conductivity of the conductive nonwoven fabric Can be further improved.

  Furthermore, the average length of the conductive fibers is preferably 10 μm or more, and more preferably 50 μm or more. Further, the average length of the conductive fibers is preferably 2000 μm or less, and more preferably 1000 μm or less. If conductive fibers having an average length within the above range are used, the conductivity of the conductive nonwoven fabric obtained can be further improved.

  The amount of the conductive fibers contained in the conductive nonwoven fabric is preferably 5 parts by mass or more, more preferably 25 parts by mass or more per 100 parts by mass of the fibrous carbon nanostructure described above. 200 parts by mass or more, more preferably 300 parts by mass or more, particularly preferably 4000 parts by mass or less, more preferably 1600 parts by mass or less, and 800 parts by mass or less. More preferably, it is particularly preferably 600 parts by mass or less. When the amount of the conductive fiber is within the above range, the conductivity of the conductive nonwoven fabric can be further improved.

<Other ingredients>
In addition, as another component which can be contained arbitrarily in a conductive nonwoven fabric, well-known additives, such as a dispersing agent used at the time of preparation of a conductive nonwoven fabric, are mentioned, without being specifically limited. And it is preferable that an electroconductive nonwoven fabric does not contain additives, such as a dispersing agent, but is comprised only with the fibrous carbon nanostructure and the electroconductive fiber. Here, “substantially no additives” means that no additives other than the additives that inevitably remain in the conductive nonwoven fabric due to manufacturing problems are not contained.

(Method for producing conductive nonwoven fabric)
The manufacturing method of the conductive nonwoven fabric of this invention can be used for manufacture of the conductive nonwoven fabric mentioned above. And the manufacturing method of the electroconductive nonwoven fabric of this invention is a dispersion medium from the dispersion liquid which contains fibrous carbon nanostructure, an electroconductive fiber, and a dispersion medium, and further further contains additives, such as a dispersing agent. And a step of forming a conductive nonwoven fabric (nonwoven fabric formation step). In addition, the manufacturing method of the conductive nonwoven fabric of this invention may include the process (dispersion liquid preparation process) of preparing the said dispersion liquid used for formation of a conductive nonwoven fabric before a nonwoven fabric formation process.
And since the conductive nonwoven fabric obtained using the manufacturing method of the conductive nonwoven fabric of this invention contains both the fibrous carbon nanostructure and conductive fiber, it exhibits the outstanding electroconductivity.

<Dispersion preparation process>
In the dispersion preparation step, the above-described fibrous carbon nanostructure and conductive fibers and any additive are dispersed or dissolved in a dispersion medium to prepare a dispersion. The ratio of the amount of fibrous carbon nanostructures and conductive fibers to be dispersed in the dispersion medium is usually the same as that of the fibrous carbon nanostructures and conductive fibers contained in the conductive nonwoven fabric formed using the dispersion liquid. Same as the ratio of quantity.

  Here, in the dispersion preparation step, a dispersion treatment is performed on a coarse dispersion obtained by adding fibrous carbon nanostructures, conductive fibers, and optional additives to the dispersion medium. Although it may be prepared, a dispersion treatment is performed on the coarse dispersion obtained by adding the fibrous carbon nanostructure and an optional additive to the dispersion medium to obtain a fibrous carbon nanostructure dispersion. Thereafter, it is preferable to prepare a dispersion by mixing conductive fibers with the fibrous carbon nanostructure dispersion. If fibrous carbon nanostructures that are easy to aggregate and difficult to disperse are dispersed in advance and then mixed with conductive fibers, a dispersion in which the fibrous carbon nanostructures and conductive fibers are well dispersed can be obtained. It is. And if the dispersion liquid with which the fibrous carbon nanostructure and the conductive fiber were disperse | distributed favorably is used, the conductive nonwoven fabric which is homogeneous and excellent in electroconductivity can be formed.

  Therefore, in the following, as an example of a method for preparing a dispersion in the dispersion preparation step, after obtaining a fibrous carbon nanostructure dispersion, by mixing conductive fibers into the fibrous carbon nanostructure dispersion A method for preparing the dispersion will be described in detail.

[Preparation of coarse dispersion]
The coarse dispersion liquid containing the fibrous carbon nanostructure and the optional additive is added to the dispersion medium after adding the fibrous carbon nanostructure and the optional additive, and optionally using a mixer such as a homogenizer. It can be prepared by mixing.

[[Dispersant]]
Here, the dispersant is not particularly limited as long as it can disperse the fibrous carbon nanostructure and can be dissolved in the dispersion medium described later. However, a surfactant, a synthetic polymer, or a natural polymer is used. Can do.
Specifically, examples of the surfactant include sodium dodecyl sulfonate, sodium deoxycholate, sodium cholate, sodium dodecylbenzene sulfonate, and the like.
Examples of the synthetic polymer include polyether diol, polyester diol, polycarbonate diol, polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, and silanol group-modified. Polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy system Resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin, alkyd resin, phenol resin, Polyacrylamide, polyacrylic acid, polystyrene sulfonic acid, polyethylene glycol, and polyvinylpyrrolidone.
Furthermore, examples of natural polymers include polysaccharides such as starch, pullulan, dextran, dextrin, guar gum, xanthan gum, amylose, amylopectin, alginic acid, gum arabic, carrageenan, chondroitin sulfate, hyaluronic acid, curdlan, chitin, chitosan, Examples thereof include cellulose and salts or derivatives thereof. The “derivative” means a conventionally known compound such as ester or ether.
These dispersants can be used singly or in combination of two or more.

[[Dispersion medium]]
Further, the dispersion medium is not particularly limited, and examples thereof include water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, Alcohols such as decanol and amyl alcohol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as diethyl ether, dioxane and tetrahydrofuran, N, N-dimethylformamide, N-methyl Examples include amide polar organic solvents such as pyrrolidone, and aromatic hydrocarbons such as toluene, xylene, chlorobenzene, orthodichlorobenzene, and paradichlorobenzene. These may be used alone or in combination of two or more.

[Preparation of fibrous carbon nanostructure dispersion]
The dispersion treatment for preparing the fibrous carbon nanostructure dispersion by subjecting the coarse dispersion to a dispersion treatment is not particularly limited, and a known dispersion treatment can be used. Specifically, as the dispersion process, a dispersion process capable of obtaining a cavitation effect or a crushing effect can be used. In addition, the dispersion process which can obtain a cavitation effect is a dispersion method using a shock wave generated when a vacuum bubble generated in the liquid bursts when high energy is applied to the liquid. Specific examples of the dispersion treatment that can provide a cavitation effect include dispersion treatment using an ultrasonic homogenizer, dispersion treatment using a jet mill, and dispersion treatment using a high shear stirrer. In addition, the dispersion treatment that can obtain the crushing effect is to apply shear force to the coarse dispersion to crush and disperse the aggregates of the fibrous carbon nanostructures, and further to apply a back pressure to the coarse dispersion. This is a dispersion method in which fibrous carbon nanostructures are uniformly dispersed in a dispersion medium while suppressing the generation of bubbles. And the dispersion | distribution process from which a crushing effect is acquired can be performed using a commercially available dispersion | distribution system (For example, product name "BERYU SYSTEM PRO" (product made from a beautiful grain) etc.).

  In particular, as a dispersion treatment when preparing a fibrous carbon nanostructure dispersion liquid, a dispersion treatment apparatus having a thin tube flow path is used, and the coarse dispersion liquid is pumped to the thin tube flow path to apply shear force to the coarse dispersion liquid. Dispersion treatment in which the fibrous carbon nanostructure is dispersed is preferable. If the fibrous carbon nanostructure is dispersed by pumping the coarse dispersion liquid into the capillary channel and applying shear force to the coarse dispersion liquid, the occurrence of damage to the fibrous carbon nanostructure is suppressed and the fibrous carbon nanostructure is suppressed. The carbon nanostructure can be well dispersed.

  Here, as a dispersion processing apparatus provided with a thin tube flow path, for example, a wet jet mill (for example, product names “JN5”, “JN10”, “JN20”, “JN100”, “JN1000” (all manufactured by Joko Corporation) And the above-mentioned dispersion system (product name “BERYU SYSTEM PRO” manufactured by Mie Co., Ltd.) and the like.

  And the single thin tube flow path with which the said dispersion processing apparatus is provided may be a single thin tube flow path, and may be a plurality of thin tube flow paths having a merging portion at an arbitrary position on the downstream side. However, from the viewpoint of imparting shear force by colliding the coarse dispersions more effectively, the capillary channels provided in the dispersion treatment apparatus are a plurality of capillary channels having a merging portion at an arbitrary position on the downstream side. Preferably there is.

  Further, the diameter of the narrow channel provided in the dispersion processing device is not particularly limited, but is 50 μm or more and 1000 μm or less from the viewpoint of effectively imparting high-speed shear to the coarse dispersion without clogging the coarse dispersion. It is preferably 50 μm or more and 600 μm or less.

  Further, the means for pumping the coarse dispersion liquid into the narrow channel is not particularly limited, and a high-pressure pump or a cylinder having a piston structure can be used.

  And the pressure at the time of pumping a rough dispersion liquid to a thin tube flow path is not specifically limited, It is preferable to set it as 60 Mpa or more and 200 Mpa or less. If the pressure at the time of pumping the coarse dispersion is within the above range, the fibrous carbon nanostructure can be satisfactorily dispersed while sufficiently suppressing the occurrence of damage to the fibrous carbon nanostructure.

  Moreover, it is preferable that the conditions (pressure, the number of treatments, etc.) of the dispersion treatment using the narrow tube flow path are such that aggregates of 1 mm or more are not visually confirmed in the obtained fibrous carbon nanostructure dispersion liquid, More preferably, the condition is such that the fibrous carbon nanostructures are dispersed at a level where the median diameter (average particle diameter in terms of volume) when measured with a particle size distribution meter is 60 μm or less. If the fibrous carbon nanostructure is well dispersed, the conductivity of the conductive nonwoven fabric formed using the fibrous carbon nanostructure dispersion can be further improved.

[Mixing of conductive fibers (preparation of dispersion)]
Mixing of the fibrous carbon nanostructure dispersion liquid and the conductive fiber is not particularly limited, and can be performed using, for example, a mixer such as a homogenizer.

<Nonwoven fabric formation process>
In the nonwoven fabric forming step, the dispersion medium is removed from the dispersion containing the fibrous carbon nanostructure, the conductive fibers, the dispersion medium, and any additive to form a conductive nonwoven fabric. Specifically, in the non-woven fabric forming step, for example, a conductive non-woven fabric is formed by filtering the dispersion using a porous substrate and drying the obtained filtrate.
In addition, you may wash | clean the filtrate obtained by filtering a dispersion liquid using water, alcohol, etc., before making it dry.

Here, the porous substrate is not particularly limited, and examples thereof include a filter sheet, and a porous sheet made of cellulose, nitrocellulose, alumina or the like.
Moreover, as a filtration method, known filtration methods, such as natural filtration, reduced pressure filtration, pressure filtration, and centrifugal filtration, can be used.

  Furthermore, as a method for drying the filtrate, a known drying method can be employed. Specifically, examples of the drying method include a hot air drying method, a vacuum drying method, a hot roll drying method, and an infrared irradiation method. Although a drying temperature is not specifically limited, Usually, it is room temperature-200 degreeC, and although drying time is not specifically limited, Usually, it is 0.1 to 150 minutes.

<Properties of conductive nonwoven fabric>
And the conductive nonwoven fabric obtained through the said nonwoven fabric formation process is excellent in self-supporting property, can peel from a porous base material, and can be used as a self-supporting film | membrane. The conductive nonwoven has a thickness 10Nm～3myuemu, it is preferable to maintain the shape of the nonwoven fabric without a support in a size area of 1 mm ² 100 cm ^2.

Moreover, the conductive nonwoven fabric obtained through the nonwoven fabric formation step is formed by entanglement of the fibrous carbon nanostructure and the conductive fiber during filtration, and the density is usually 1.0 g / cm ^3. Hereinafter, the weight is preferably 0.5 g / cm ³ or less, more preferably 0.3 g / cm ³ or less.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%” and “part” representing amounts are based on mass unless otherwise specified.
In the examples and comparative examples, the conductivity of the conductive nonwoven fabric was measured using the following method.

<Conductivity>
Four square test pieces having a size of 10 mm × 10 mm were cut out from the produced conductive nonwoven fabric and used as measurement samples.
And the electrical conductivity of the measurement sample was measured by the method based on JISK7194 using the low resistivity meter (the Mitsubishi Chemical Analytech Co., Ltd. make, product name "Loresta (trademark) GPMCP-T610"). Specifically, the measurement sample is fixed on the insulating board, the LSP probe is pressed against the center position of the measurement sample (vertical 5 mm, horizontal 5 mm), and a voltage of 10 V is applied to determine the conductivity of each measurement sample. It was measured. And the average value of the measured value was calculated | required and it was set as the electrical conductivity of the conductive nonwoven fabric.

(Example 1-1)
<Preparation of fibrous carbon nanostructure A containing CNT>
SGCNT was prepared according to the super growth method (see International Publication No. 2006/011655) to obtain a fibrous carbon nanostructure A.
The average diameter of the fibrous carbon nanostructure A measured with a transmission electron microscope (H-7650, manufactured by Hitachi High-Technologies Corporation) was 3 nm. Moreover, the BET specific surface area of the fibrous carbon nanostructure A measured using a specific surface area meter (SA-3100, manufactured by Beckman Coulter) was 800 m ² / g.
<Preparation of conductive fiber>
Pitch-based carbon fiber (manufactured by Mitsubishi Plastics, DIALEAD (registered trademark) K223HM) was prepared as the conductive fiber.
In addition, the average fiber diameter of the pitch-type carbon fiber measured using the scanning electron microscope (Hitachi High-Technologies make, S-4300) was 10 micrometers.
<Preparation of dispersion>
400 mg of fibrous carbon nanostructure A was put into 2 L of methyl ethyl ketone and stirred for 2 minutes with a homogenizer to prepare a crude dispersion.
Next, the obtained coarse dispersion is passed through a wet jet mill (manufactured by Joko Co., Ltd., JN20) having a narrow tube flow path having a diameter of 0.5 mm for two cycles at a pressure of 100 MPa, so that the fibrous carbon nanostructure A Was dispersed in methyl ethyl ketone to obtain a fibrous carbon nanostructure dispersion liquid A having a concentration of 0.20%. In addition, the median diameter (average particle in terms of volume) of the fibrous carbon nanostructure A in the fibrous carbon nanostructure dispersion A using a laser diffraction / scattering particle size distribution measuring apparatus (LA-960, manufactured by Horiba, Ltd.) As a result, the median diameter was 60 μm.
Thereafter, 1600 mg of pitch-based carbon fibers as conductive fibers were added to the obtained fibrous carbon nanostructure dispersion liquid A, and stirred for 2 minutes with a homogenizer to obtain a dispersion liquid.
<Manufacture of conductive nonwoven fabric>
16 g of the obtained dispersion was filtered under reduced pressure using Kiriyama filter paper (No. 5A, diameter 3 cm), and the filtrate was dried in an atmosphere at a temperature of 80 ° C. for 60 minutes to give a sheet-like conductive nonwoven fabric (density 0.23 g). / Cm ³ ). And after cooling to room temperature, the electroconductive nonwoven fabric was peeled off from the filter paper, and the electrical conductivity of the electroconductive nonwoven fabric was measured. The results are shown in Table 1.

(Examples 1-2 to 1-6)
The compounding amounts of pitch-based carbon fibers as conductive fibers are 40 mg (Example 1-2), 100 mg (Example 1-3), 200 mg (Example 1-4), and 800 mg (Example 1-5), respectively. A dispersion and a conductive nonwoven fabric were produced in the same manner as in Example 1-1 except that the amount was changed to 3200 mg (Example 1-6). And it evaluated similarly to Example 1-1. The results are shown in Table 1.

(Comparative Example 1-1)
A conductive nonwoven fabric was produced using only the fibrous carbon nanostructure dispersion liquid A having a concentration of 0.20% without using pitch-based carbon fibers. Specifically, 16 g of fibrous carbon nanostructure dispersion liquid A was filtered under reduced pressure using Kiriyama filter paper (No. 5A, diameter 3 cm), and the filtrate was dried for 60 minutes in an atmosphere at a temperature of 80 ° C. A conductive nonwoven fabric was produced. And it evaluated similarly to Example 1-1. The results are shown in Table 1.

  From Table 1, the conductive nonwoven fabrics of Examples 1-1 to 1-6 formed using fibrous carbon nanostructures A and pitch-based carbon fibers were formed using only fibrous carbon nanostructures A. It turns out that the electroconductivity superior to the electroconductive nonwoven fabric of the comparative example 1-1 which performed was demonstrated. Especially, it turns out that the electroconductive nonwoven fabric of Examples 1-1, 1-4, and 1-5 exhibits the especially outstanding electroconductivity.

(Example 2-1)
In the same manner as in Example 1-1, except that a fibrous carbon nanostructure B made of a commercially available multilayer CNT (product name “K-NANO”) was used instead of the fibrous carbon nanostructure A, A fibrous carbon nanostructure dispersion liquid B having a concentration of 0.20%, a dispersion liquid, and a conductive nonwoven fabric were produced. And it evaluated similarly to Example 1-1. The results are shown in Table 2.
The average diameter of the fibrous carbon nanostructure B measured using a transmission electron microscope (H-7650, manufactured by Hitachi High-Technologies Corporation) was 13 nm. Further, the BET specific surface area of the fibrous carbon nanostructure B measured using a specific surface area meter (SA-3100, manufactured by Beckman Coulter) was 266 m ² / g.

(Examples 2-2 to 2-7)
The compounding amounts of pitch-based carbon fibers as conductive fibers are 40 mg (Example 2-2), 100 mg (Example 2-3), 200 mg (Example 2-4), and 800 mg (Example 2-5), respectively. A dispersion and a conductive nonwoven fabric were produced in the same manner as in Example 2-1, except that they were changed to 3200 mg (Example 2-6) and 6400 mg (Example 2-7). And it evaluated similarly to Example 2-1. The results are shown in Table 2.

(Comparative Example 2-1)
A conductive nonwoven fabric was produced using only the fibrous carbon nanostructure dispersion liquid B having a concentration of 0.20% without using pitch-based carbon fibers. Specifically, 16 g of fibrous carbon nanostructure dispersion B was filtered under reduced pressure using Kiriyama filter paper (No. 5A, diameter 3 cm), and the filtrate was dried for 60 minutes in an atmosphere at a temperature of 80 ° C. A conductive nonwoven fabric was produced. And it evaluated similarly to Example 2-1. The results are shown in Table 2.
In addition, the conductive nonwoven fabric of Comparative Example 2-1 contracted and cracked when dried, and was inferior in self-supporting property as compared with the conductive nonwoven fabrics of Examples 2-1 to 2-7.

  From Table 2, the conductive nonwoven fabrics of Examples 2-1 to 2-7 formed using fibrous carbon nanostructures B and pitch-based carbon fibers were formed using only fibrous carbon nanostructures B. It turns out that the electroconductivity superior to the electroconductive nonwoven fabric of the comparative example 2-1 which performed was demonstrated. Especially, it turns out that the conductive nonwoven fabrics of Examples 2-1 and 2-3 to 2-7 exhibit particularly excellent conductivity.

Moreover, from Table 1 and Table 2, the conductive nonwoven fabrics of Examples 1-1 to 1-6 using SGCNT having a large BET specific surface area are Examples 2-1 to 2 using multilayer CNT having a small BET specific surface area. It turns out that it has conductivity higher than the conductive nonwoven fabric of -7.
On the other hand, from Table 1 and Table 2, the conductive nonwoven fabrics of Examples 2-1 to 2-7 using multi-walled CNTs having a small BET specific surface area were comparative examples 2 formed using only fibrous carbon nanostructures. It can be seen that the range of improvement in conductivity with respect to 1 conductive nonwoven fabric is very large.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive nonwoven fabric excellent in electroconductivity can be provided.

Claims (7)

  A conductive nonwoven fabric comprising a fibrous carbon nanostructure and conductive fibers.   The conductive nonwoven fabric according to claim 1, wherein the conductive fiber is contained in a proportion of 5 parts by mass or more and 4000 parts by mass or less per 100 parts by mass of the fibrous carbon nanostructure. The conductive nonwoven fabric according to claim 1 or 2, wherein the fibrous carbon nanostructure has a BET specific surface area of 600 m ² / g or less.   The electrically conductive nonwoven fabric in any one of Claims 1-3 in which the said fibrous carbon nanostructure contains a carbon nanotube.   The electroconductive nonwoven fabric in any one of Claims 1-4 in which the said electroconductive fiber contains carbon fiber. A method for producing a conductive nonwoven fabric according to any one of claims 1 to 5,
The manufacturing method of an electroconductive nonwoven fabric including the process of removing the said dispersion medium from the dispersion liquid containing a fibrous carbon nanostructure, an electroconductive fiber, and a dispersion medium, and forming an electroconductive nonwoven fabric.   A coarse dispersion obtained by adding the fibrous carbon nanostructure to the dispersion medium is pumped to a capillary channel at a pressure of 60 MPa or more and 200 MPa or less, and a shear force is applied to the coarse dispersion to obtain an average particle size. The method further comprises a step of preparing the dispersion by mixing the conductive fiber with the fibrous carbon nanostructure dispersion after obtaining a dispersion of the fibrous carbon nanostructure having a thickness of 60 μm or less. A method for producing a conductive nonwoven fabric.