JP5178509B2 - Method for producing conductive material using carbon nanotube, and electric double layer capacitor using conductive material - Google Patents

Description

The present invention relates to method for producing a conductive material using the card must be installed carbon nanotubes. The conductive material produced by the method of the present invention can be applied as, for example, a polarizable electrode that is a main constituent member of an electric double layer capacitor capable of storing a large amount of electricity.

  Throughout the claims and the specification, “carbon nanotube” means a plurality of brush-like carbon nanotubes.

  Carbon nanotubes are made of ultra-fine cylinders (tubes) that are usually nano-sized (one nano is one billionth) in diameter, with a graphite sheet formed by continuously forming six-membered rings of carbon atoms. It is a material and a material with a very large aspect ratio. Carbon nanotubes have various unique properties such as chemical stability, high strength, and a wide range of electrical properties, and are therefore expected to be industrially applied as new carbon materials.

  As one of the applications, application to a polarizable electrode which is a constituent member of an electric double layer capacitor is cited. An energy regenerative system using an electric double layer capacitor has a semi-permanent life, contains almost no environmental load substance, and is excellent in instantaneous charge / discharge characteristics. In recent years, carbon dioxide emission suppression technology for global environmental problems has become an important issue, and the regeneration system described above has been actively developed to store and reuse the wasteful electricity.

  The inventors of the present invention previously described a carbon nanotube conductive material obtained by transferring carbon nanotubes grown on a substrate onto a conductive film or a conductive adhesive layer in a direction substantially perpendicular to the surface thereof, A manufacturing method and an electrode using the same have been proposed (see Patent Document 1 and Patent Document 2).

  Applications of energy regenerative systems using electric double layer capacitors tend to be widespread, and for this purpose, they are cheaper, more productive, and can withstand use in more severe conditions, such as high temperature environments. Is required.

  Further, the shape of the energy regeneration system is required to be short, small and light like other electronic components, circuits, etc., and a more efficient large capacity electric double layer capacitor is desired. The electric capacity charged to the electric double layer capacitor is, of course, better when it is larger, but the electric capacity of the electric double layer capacitor becomes larger as the operating voltage is higher, as shown by the following equation [I]. It is advantageous.

E = 1 / 2CV ² ……… [I]
In general, in an electric double layer capacitor, an organic electrolyte can be operated at a higher voltage, but recently, due to the advancement of constituent materials, a higher voltage than an organic electrolyte electric double layer capacitor is possible. Can be used. A method for measuring the operating voltage will be described later.

  Further, in order to increase the capacity of the electric double layer capacitor, it is necessary to further reduce the thickness of the component parts and lower the resistance of the polarizable electrode. The reduction in the thickness of the component enables the electric double layer capacitor to be reduced in size and thickness, and the reduction in the resistance of the polarizable electrode can lead to an improvement in the electric conductivity of the electric double layer capacitor itself and, consequently, an increase in capacity.

Carbon nanotubes are attracting attention for their effectiveness as electron-emitting electron sources because of their properties such as high conductivity, robustness, and high aspect ratio, and many studies have been made. For example, a method of manufacturing a field emission cold cathode in a process of transferring carbon nanotubes having vertical orientation to the surface of a patterned conductive binder (see Patent Document 3), carbon nanotubes having vertical orientation Is transferred and fixed to a functional sheet having various characteristics, and a method of forming a sheet having a three-layer structure for the purpose of enhancing the convenience in handling while maintaining the orientation (see Patent Document 4) Synthesizing an aligned carbon nanotube layer on a first substrate capable of supporting the growth of carbon nanotubes, applying a second substrate layer of polymer film on top of the same layer, removing the first substrate, A method for providing an aligned carbon nanotube film supported on a second substrate (see Patent Document 5) has been proposed.
JP 2004-30926 A JP 2004-127737 A JP 2004-281388 A JP 2005-7861 A Special table 2003-500325 gazette

  As shown in FIG. 3, the carbon nanotube conductive material described in Patent Document 1 substantially includes brush-like carbon nanotubes (51) grown using catalyst particles on a substrate as nuclei on a conductive film (52). The conductive film (52) is inferior in heat resistance and strength because it is formed by adding a polyethylene layer (54). Therefore, when the ambient temperature reaches or exceeds the melting temperature of polyethylene, the carbon nanotubes (51) transferred so as to pierce the conductive film (52) substantially vertically cannot maintain the vertical alignment. There is a risk of dropping out.

  Further, since the polyethylene-based conductive film and porous film, and the polymer film of Patent Document 5 are inferior in strength, as shown in FIG. 4, the conductive film (52) and the reinforcing layer (55) laminated thereon are provided. A multilayer film (56) made of may be used. In this case, however, the total thickness of the film must be increased.

  Furthermore, in the carbon nanotube transfer process, the conductive film before transfer is once heated above the softening temperature, transferred and held in that state, and then softened to hold the carbon nanotubes on the conductive film. It was necessary to cool to below the temperature, and a series of these steps required a long time, which was a cause of poor productivity. Moreover, carbon nanotubes could not be transferred reliably, and carbon nanotubes grown on the substrate remained, or the polyethylene layer of the conductive film melted and peeled.

  As shown in FIG. 5, the carbon nanotube conductive material described in Patent Document 2 includes a conductive adhesive layer (63) in which carbon nanotubes (63) grown with catalyst particles as nuclei are laminated on a base material (61). 62). However, a thermoplastic resin such as a polyvinyl chloride resin is suitable as the adhesive, but this conductive material is also heat resistant and carbon at a high temperature above the melting temperature, as in the above-mentioned Patent Document 1. In addition, the carbon nanotube transfer process takes a long time (for example, 10 to 30 minutes) to reliably hold the carbon nanotube, and the productivity is still inferior.

  When this conductive material is used as a polarizable electrode of an electric double layer capacitor, since the transferred carbon nanotubes are simply bonded on the surface of the adhesive layer, they are equivalent to the conductive material of Patent Document 1. The carbon nanotubes may be detached due to external factors such as temperature change, and the reliability is poor.

  Furthermore, since the conductive adhesive layer is inferior in strength, the conductive material to which the carbon nanotubes are transferred needs to be bonded to a support such as a film, sheet, or thin plate made of an inorganic or organic synthetic resin. The thickness as a material had to be large.

  Further, since the reaction current is generated in a relatively low voltage region when the conductive material according to Patent Document 2 is used as a polarizable electrode for an electric double layer capacitor, the high voltage region of the electrolytic solution is obtained. It could not withstand use in Therefore, it has been unsatisfactory in terms of characteristics as a polarizable electrode for a large-capacity electric double layer capacitor.

  In Patent Document 3, a conductive binder layer patterned on a substrate is adhered to the surface thereof, a step of adhering oriented carbon nanotubes, a step of curing the conductive binder layer as necessary, and a conductive binder layer adhered to the conductive binder layer. A method of manufacturing a field emission cold cathode comprising a step of peeling off a substrate leaving only an oriented carbon nanotube portion is described. In addition, a method for transferring oriented carbon nanotubes to a flexible substrate having a reversible adhesive surface and a method for immobilizing oriented carbon nanotubes on an electrode are described.

  However, there has been little characterization on the conductive binder and the flexible substrate having a reversible adhesive surface in this method, and in any case, the transferred carbon nanotubes are simply surface tacky. Alternatively, it is bonded to the surface and is not intended to be fixed so as to maintain complete and high reliability. Moreover, since the said transfer process is performed under heating in argon atmosphere and cooling is required after that, production efficiency is inferior similarly to patent document 1. FIG.

  As shown in FIG. 6, Patent Document 4 proposes a functional sheet having a three-layer structure intended to prevent contamination and improve convenience during the transfer of oriented carbon nanotubes. Two functional sheets (72) and (73) arranged on both surfaces of the oriented carbon nanotube film (71) fix the carbon nanotube film (71). The immobilization of the carbon nanotube film (71) is described as meaning that the surfaces of the functional sheets (72) and (73) and the surface of the oriented carbon nanotube film (71) contact and adhere. For this reason, when using the conductive material obtained by patent document 4 as an electrode, like the above-mentioned patent document, there exists a possibility that the orientation of carbon nanotube may be disordered or fallen, and this conductive material is carbon nanotube. It is inferior in holding reliability and may not be used.

  For this reason, when using the conductive material obtained by patent document 4 as an electrode, like the above-mentioned patent document, there exists a possibility that the orientation of carbon nanotube may be disordered or fallen, and this conductive material is carbon nanotube. It is inferior in holding reliability and may not be used. The same applies to the case where the functional sheet on one side is peeled off and the functional sheet on the other side is cured to fix the carbon nanotube film and used as it is. Since the conductive material is held only by adhesion, the conductive material is still inferior in the reliability of holding the carbon nanotube when it is assumed to be used as an electrode.

Accordingly, an object of the present invention is to solve the problems in the above-mentioned patent documents, to maintain a thinner and high conductivity, excellent in strength and reliability of carbon nanotube retention, and excellent in production efficiency and suitable for mass production. And providing a method for producing a conductive material using carbon nanotubes, which is advantageous in terms of cost. In addition, the present invention provides a large capacity in which the conductive material is used as a polarizable electrode because the conductive material can maintain a thinner and higher conductivity and the operation is ensured in a high voltage region. Another object is to provide an electric double layer capacitor.

As a result of repeated researches to solve the above problems, the inventors of the present invention are thinner and have higher conductivity, strength, reliability of holding carbon nanotubes, excellent mass productivity, and advantageous in cost. In order to produce a conductive material using carbon nanotubes, a conductive material formed by transferring carbon nanotubes to the surface of a previously formed epoxy resin composition layer so that the carbon nanotubes penetrate the resin composition layer. The manufacturing method of the property material was discovered.

  Moreover, when this electroconductive material was used as a polarizable electrode, it discovered that it could become a high capacity | capacitance electric double layer capacitor by ensuring low resistance and a high operating voltage.

That is, the present invention includes a step of forming an epoxy resin composition layer (2) containing a curing agent in a B-stage state on a substrate (1) made of a film, and catalyst particles as nuclei on a substrate (3). A step of growing carbon nanotubes (4) to produce a substrate (5) with carbon nanotubes that is substantially vertically aligned on the substrate (3), a substrate with carbon nanotubes (5), and an epoxy resin composition layer (2) Is heated to 50 ° C. or higher and 200 ° C. or lower, the substrate (5) with carbon nanotubes is pressed from the tip of the carbon nanotubes onto the surface of the resin composition layer (2), and the tip is inserted into the epoxy resin composition layer (2). The step of passing the composition layer (2) through and bringing the tip of the carbon nanotube into contact with the base material (1), and then the carbon nanotube (4) with the epoxy resin The step of peeling the silicon substrate (3) from the carbon nanotube (4) so as to remain in the composition layer (2), and the epoxy resin composition of the base material (1) with the obtained carbon nanotube embedded epoxy resin composition layer A step of curing the layer (2), and after curing, the base material (1) made of a film is peeled from the cured epoxy resin layer (6), and the carbon nanotubes (4) are bonded to the cured epoxy resin layer (6). The carbon nanotube (4) has pierced substantially perpendicularly to the surface of the cured epoxy resin layer (6), and the cured resin layer (6) is obtained. penetrating though in a state of reaching the opposite surface, characterized in Rukoto, there is provided a method for producing a conductive material using a carbon nanotube.

In the present invention , the carbon nanotubes are transferred to the epoxy resin composition layer, pierced substantially perpendicularly to the surface thereof, and maintained in a state of being penetrated through the resin composition layer. The carbon nanotubes are securely held in the resin composition layer by penetrating the epoxy resin composition layer, and the reliability of holding the carbon nanotubes is greatly improved as compared with the prior art.

  Carbon nanotubes that are substantially vertically aligned on the substrate can be produced by a known method. For example, a solution containing a metal complex such as nickel, cobalt, or iron is applied to at least one surface of a silicon substrate by spraying or brushing, and then heated to form a film, or cluster the particles of the metal or a compound thereof. A film is formed by striking the substrate with a gun. The coating is preferably heated in an inert gas atmosphere at 700 to 800 ° C., preferably for 1 to 30 minutes, to form catalyst particles from the coating. Preferably, carbon particles having a diameter of 10 to 38 nm, a length of 1 to 300 μm, and a distance between carbon nanotubes of 10 to 1000 nm are obtained by subjecting the obtained particles to a general chemical vapor deposition method (CVD method) using acetylene gas. Nanotubes are brushed on the substrate in a multilayer structure.

  The carbon nanotubes preferably have a multilayer structure, and the outer diameter is preferably 10 to 30 nm. An electric double layer capacitor configured using such a carbon nanotube as a polarizable electrode exhibits good charge / discharge characteristics.

The epoxy resin composition layer to which the carbon nanotubes are to be transferred and which contains a curing agent is further composed of a) a polyfunctional epoxy resin having three or more epoxy groups in the molecule, b) a phenoxy resin, c) a synthetic rubber or a derivative thereof. And d) it preferably contains at least one of polyamide resins or derivatives thereof.

Since the epoxy resin composition containing a curing agent includes at least one of the above components a) to d), an appropriate elasticity can be obtained, so that the carbon nanotubes can be easily transferred to the epoxy resin composition layer, and the epoxy It is held in a state of penetrating the resin composition layer.

  The epoxy resin composition layer preferably further contains a conductive filler. By adding the conductive filler, the electrical bondability between the carbon nanotubes is improved, whereby the conductivity is improved and the internal resistance of the obtained conductive material can be reduced.

The present invention provides a method for producing a conductive material using the card must be installed carbon nanotubes. In the method according to the present invention, carbon nanotubes grown with catalyst particles on the substrate as nuclei are transferred to the epoxy resin composition layer, pierced in a direction substantially perpendicular to the surface, and penetrated through the resin composition layer. A method for producing a conductive material using carbon nanotubes, wherein the epoxy resin composition layer is heated to 50 ° C. or higher and 200 ° C. or lower before transfer.

  In the method for producing a conductive material according to the present invention, the epoxy resin composition layer is preferably in a B-stage state (semi-cured state) before the heating.

  The epoxy resin composition layer contains at least one of the above components a) to d), so that the carbon nanotube has appropriate elasticity for transferring the carbon nanotube, and the carbon nanotube facilitates the resin composition layer. Can penetrate.

  Moreover, when the same resin composition layer is heated on said conditions, a carbon nanotube can be reliably hold | maintained in the state which penetrated the same resin composition layer. In addition, since the thickness of the resin composition layer and the base material for forming the resin composition layer can be made extremely thin, the carbon nanotube is transferred to the fat composition layer immediately after the transfer of the carbon nanotubes. By peeling, a target conductive material can be obtained. Therefore, a forced cooling process is not necessary after transfer.

Furthermore, by heating the resin composition layer in the B-stage state, it is possible to further enhance the effect that the carbon nanotubes can be reliably held in a state of penetrating the resin composition layer.

The present invention provides an electric double layer capacitor using the conductive material produced by the above method as a polarizable electrode. By using the above conductive material for the polarizable electrode, it is possible to realize a large-capacity electric double layer capacitor by ensuring a low resistance and a high operating voltage.

The present invention also provides a large-capacity electric double layer capacitor in which a higher operating voltage is secured by using the conductive material produced by the above method as a polarizable electrode and using an ionic liquid as an electrolyte. Can be realized.

  The operating voltage of the electric double layer capacitor is determined by a potential window derived from a reaction current measured by a cyclic voltammetry method. The potential window is a range of a voltage region in which no reaction current is generated. A larger operating range ensures a higher operating voltage, and a large capacity can be realized. The generation of the reaction current means that electricity once charged in the electric double layer capacitor is lost to the outside, that is, it is difficult to operate the electric double layer capacitor in the voltage region where the reaction current is generated. .

The invention of the method for producing a conductive material using carbon nanotubes according to claim 1 is an epoxy resin composition in a B-stage state and containing a curing agent on a substrate (1) made of a film such as a polyethylene terephthalate film. A step of forming a layer (2), and a carbon nanotube substrate with carbon nanotubes that is substantially vertically aligned on the substrate (3) by growing carbon nanotubes (4) on the substrate (3) such as a silicon substrate with the catalyst particles as nuclei. (5) is prepared, and the substrate with carbon nanotubes (5) and the epoxy resin composition layer (2) are heated, and the substrate with carbon nanotubes (5) is placed on the surface of the resin composition layer (2). Press from the tip, insert the tip into the epoxy resin composition layer (2) to penetrate the composition layer (2), The step of bringing the tube tip into contact with the substrate (1), and then the substrate (3) is peeled from the carbon nanotubes (4) so that the carbon nanotubes (4) remain in the epoxy resin composition layer (2). A step of curing the epoxy resin composition layer (2) of the obtained substrate with carbon nanotube embedded epoxy resin composition layer (1), and curing the substrate (1) comprising a film after curing. And a step of obtaining a conductive material (7) in which the carbon nanotubes (4) are planted in the cured epoxy resin layer (6) by peeling from the physical layer (6), and the carbon nanotubes (4) are cured epoxy resin to the layer (6) surface, and it stuck to the substantially vertical, in which characterized that you have in a state of reaching the opposite surface through the cured resin layer (6),請According to the invention described in claim 1, by an epoxy resin composition layer before heating is B-stage state, it is possible to hold the carbon nanotubes while reliably penetrate into the resin composition layer. In addition , by heating the epoxy resin composition layer to a specific temperature range before transfer, the resin composition layer has appropriate flexibility for transfer, and the transferred carbon nanotubes have the same resin composition layer. It can be held in a penetrating state.
The conductive material produced by the method of the present invention has a structure in which carbon nanotubes penetrate the epoxy resin composition layer, so that the strength and reliability of holding the carbon nanotubes are excellent, thinner and highly conductive, The operation voltage is high, the operation is ensured in a high voltage region, the production efficiency is excellent, and it is suitable for mass production, which is advantageous in terms of cost.

  Moreover, since a carbon nanotube penetrates an epoxy resin composition layer, when the epoxy resin composition layer is formed on a base material, it will be in direct contact with the base material surface. Therefore, when a conductive material formed by raising carbon nanotubes in a laminate composed of an epoxy resin composition layer and its base material is used as a collecting electrode, the high conductivity of the carbon nanotubes becomes the conductivity of the electrode itself. On the other hand, a synergistic effect can be expressed and a low-resistance electrode can be formed.

According to the invention described in claim 2, the epoxy resin composition layer containing a curing agent further contains at least one of specific components a) to d), so that the effect of the invention described in claim 1 can be achieved. In addition, the epoxy resin composition layer has an appropriate elasticity, so that the carbon nanotubes are easily transferred to the epoxy resin composition layer and are held in a state of penetrating the epoxy resin composition layer.

According to the invention described in claim 3, the epoxy resin composition layer containing a curing agent further contains a conductive filler, so that in addition to the effects of the inventions described in claims 1 and 2, By improving the general bonding property, the conductivity can be improved and the internal resistance can be reduced as a conductive material.

According to the invention described in claim 4, by using the conductive material produced by the method for producing a conductive material of the present invention as an electrode of an electric double layer capacitor, it is thinner and has a high operating voltage and a high voltage. The operation is ensured in the region, and a large capacity electric double layer capacitor material can be provided.

According to invention of Claim 5 , the said effect by the invention of Claim 4 can be improved further.

  Embodiments of the present invention will be described below.

  First, the formation of carbon nanotubes will be described.

  Catalyst particles are formed on a substrate, and carbon nanotubes are grown from a raw material gas in a high temperature atmosphere using the catalyst particles as nuclei. The substrate is not particularly limited as long as it supports the catalyst particles, and is preferably one in which the catalyst particles are not easily wetted, and may be a silicon substrate. The catalyst particles may be metal particles such as nickel, cobalt, and iron. A solution of a compound such as these metals or their complexes is applied to the substrate by spraying or brushing to form a film. The thickness of the film is preferably 1 to 100 nm. This film is preferably heated in an inert gas atmosphere at 700 to 800 ° C., preferably for 1 to 30 minutes, to form catalyst particles.

  As a raw material gas for carbon nanotubes, aliphatic hydrocarbons such as acetylene, methane, and ethylene can be used, and acetylene gas is particularly preferable. In the case of acetylene, carbon nanotubes having a multilayer structure and a thickness of 12 to 60 nm are formed in a brush shape on a substrate with catalyst particles as nuclei by a CVD method. The formation temperature of the carbon nanotube is preferably 650 to 800 ° C.

  Next, the epoxy resin composition will be described.

In the present invention, the epoxy resin used in the epoxy resin composition, as long as it has two or more glycidyl groups in the molecular. Examples of the epoxy resin include diglycidyl ether type, diglycidyl ester type, glycidyl amine type, linear aliphatic epoxide type, and alicyclic epoxide type. One of these may be used, or a combination of two or more may be used.

  The epoxy resin may be modified by a known method.

  The epoxy resin may be liquid, semi-solid, or solid at room temperature, but the epoxy resin composition preferably contains a single or mixed organic solvent or reactive diluent for easy handling. Various reactive diluents such as monofunctional, bifunctional, and polyfunctional can be used as appropriate. As the organic solvent, methanol, acetone, methyl ethyl ketone, toluene, methyl cellosolve, dimethylformamide and the like can be used as appropriate.

  The epoxy resin composition contains a curing agent. Examples of the curing agent include aliphatic, alicyclic and aromatic polyamines; polyamidoamines; modified polyamines; hexahydrophthalic anhydride, dodecenyl succinic anhydride, trimellitic anhydride Acid anhydrides such as 2-imidazole and derivatives thereof such as 2-methylimidazole and 2-ethyl-4-methylimidazole; dicyandiamide or derivatives thereof; organic acid dihydrazides such as sebacic acid dihydrazide; 3- (3,4-dichlorophenyl)- Examples include urea derivatives such as 1,1 dimethylurea; boron fluoride-monoethylamine complex, phenol resin, amino resin, polyisocyanate compound, diaminodiphenyl sulfone and the like. Any curing agent can be used as long as it is crosslinked and cured by a polyaddition reaction or an addition polymerization reaction with the epoxy resin used, and is not particularly limited. One type of curing agent may be used, or a combination of two or more may be used.

  The epoxy resin composition can be blended with other thermosetting resins or thermoplastic resins. Moreover, in order to give a required characteristic, it is preferable to add an organic and inorganic additive and a filler.

The epoxy resin composition layer containing a curing agent further includes a) a polyfunctional epoxy resin having three or more epoxy groups in the molecule, b) a phenoxy resin, c) a synthetic rubber or a derivative thereof, and d) a polyamide resin or a mixture thereof. It is preferable to include at least one of the derivatives.

  a) Polyfunctional epoxy resins having 3 or more epoxy groups in the molecule include phenol novolac epoxy resins, cresol novolac epoxy resins, triglycidyl-p-aminophenol, triglycidyl isocyanurate, tetraglycidyl metaxylenediamine, Polyfunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane and tetraglycidyl-1,3-bisaminomethylcyclohexane can be exemplified. Of these polyfunctional epoxy resins, it is preferable to use a phenol novolac type epoxy resin or a cresol novolac type epoxy resin from the viewpoint of the heat resistance of the epoxy resin composition layer and the ease of transfer of the carbon nanotubes.

Moreover, when adding the said polyfunctional epoxy resin to the epoxy resin composition containing a hardening | curing agent, it is preferable to add 5-50 mass parts with respect to 100 mass parts of epoxy resin compositions containing the same hardening | curing agent . When this addition amount is less than 5 parts by mass or more than 50 parts by mass, it becomes difficult to transfer the carbon nanotubes through the epoxy resin composition layer containing the same curing agent .

  b) A phenoxy resin is generally a linear epoxy resin having a molecular weight of 30000 or more, and has a thermoplastic resin characteristic. In the present invention, those having a basic structure of either bisphenol A type or bisphenol F type can be used. In addition, flame retardant modification with bromine, phosphorus or the like, or modification with other functional groups can also be used. An example of such a modified product is “Phenotote” manufactured by Toto Kasei Co., Ltd.

By adding 5 to 45 parts by mass of the phenoxy resin to 100 parts by mass of the epoxy resin composition containing a curing agent , moderate rigidity and flexibility are imparted, so that the epoxy resin composition layer is penetrated. The carbon nanotube can be transferred. When this addition amount is less than 5 parts by mass and more than 50 parts by mass , the carbon nanotubes cannot be transferred in a form penetrating the resin composition layer.

  c) The synthetic rubber may be styrene butadiene rubber, polyisoprene rubber, acrylonitrile butadiene rubber, epichlorohydrin rubber or the like. The derivative of the synthetic rubber may be a derivative obtained by modification such as hydrogenation or carboxylation of the synthetic rubber. Medium / high nitrile type, high nitrile type acrylonitrile butadiene rubber and carboxylated acrylonitrile butadiene rubber are preferable because the epoxy resin composition layer can obtain appropriate flexibility and rigidity when transferring carbon nanotubes. As an example, “Nipol” manufactured by Nippon Zeon Co., Ltd. can be mentioned. By adding synthetic rubber or its derivative to the epoxy resin composition, flexibility and rigidity are imparted to the epoxy resin composition layer, so that carbon nanotubes can be transferred through the resin composition layer. Become.

  It is also possible to use so-called rubber-modified epoxy resins obtained by modifying these synthetic rubbers with epoxy resins.

The addition amount of synthetic rubber or its derivative is 5-50 mass parts with respect to 100 mass parts of epoxy resin compositions containing a hardening | curing agent . When the addition amount is 5 parts by mass or less, it is difficult to transfer the carbon nanotubes to the resin composition. When the addition amount is 50 parts by mass or more, it is difficult to hold the transferred carbon nanotubes in the resin composition layer. Become.

A synthetic rubber or a derivative thereof may be used in combination with a suitable vulcanizing agent such as a phenol resin and a derivative thereof in order to improve the strength and adhesiveness of the rubber itself. The phenol resin and its derivative are preferably added in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the synthetic rubber or its derivative.

  d) The polyamide resin may have any basic structure such as 6-nylon or 6,6-nylon, or a copolymer thereof. As an example, CM4000 and CM8000 of copolymer nylon “Amilan” manufactured by Toray are listed. Further, elastomers or synthetic resins having a polyamide group in the molecular structure such as “Kayaflex” manufactured by Nippon Kayaku Co., Ltd. can be used. The polyamide resin or derivative thereof may be in the form of fine powder particles, liquid or solid at room temperature, and can be added in a form dissolved or dispersed in an appropriate solvent such as an organic solvent.

  By adding a polyamide resin or a derivative thereof, moderate flexibility and retention at the time of transferring the carbon nanotube can be imparted to the resin composition layer.

The amount of the polyamide resin or derivative thereof added is preferably 5 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin composition containing the curing agent . When the addition amount is less than 5 parts by mass, insufficient flexibility of the tree fat composition layer, if larger than 60 parts by weight, it is difficult to transfer carbon nanotubes is maintained at the same resin composition layer It becomes.

In order to further impart conductivity to the conductive material produced by the method of the present invention, it is preferable to include a conductive filler in the epoxy resin composition containing a curing agent . Examples of the conductive filler include carbon-based conductive pieces such as carbon nanotube pieces, carbon nanohorn pieces, carbon nanocoil pieces, conductive carbon fibers, graphite, and carbon black, or carbon-based conductive powders. These have no influence on the electrolytic solution or the like when the conductive material is used for the electric double layer capacitor, and can further reduce the resistance of the electrode itself.

  Next, the transfer of carbon nanotubes will be described.

First, an epoxy resin composition layer is formed by applying an epoxy resin composition containing a curing agent to the surface of a base material made of an inorganic material such as a metal foil or a heat-resistant film using a coater, a doctor blade, or the like. As the metal foil, a copper foil, a stainless steel foil, and an aluminum foil are preferable from the viewpoints of easy availability and economy. The heat resistant film is preferably a polyethylene terephthalate film.

  The thickness of the epoxy resin composition layer is preferably 0.1 to 1000 μm, more preferably 10 to 200 μm. If the thickness of the resin composition layer is smaller than 0.1 μm, the carbon nanotubes cannot be reliably held. If the thickness is larger than 1000 μm, it becomes extremely difficult to form the resin composition layer, which increases productivity. Inferior.

  The process of transferring the carbon nanotubes to the epoxy resin composition layer is performed at a stage where the solvent is evaporated and the resin composition is dried after the epoxy resin composition is applied to the substrate surface.

  In addition, the epoxy resin composition is applied to a base material made of a metal foil or a heat-resistant film having appropriate releasability, and after drying, the resin composition layer is formed from a laminate comprising the resin composition and the base material. Is peeled to form an epoxy resin composition film, and carbon nanotubes can be transferred to the film.

  The carbon nanotubes grown on the substrate are planted in the resin composition layer by pressing them against the epoxy resin composition layer from the tip. Thereafter, the carbon nanotubes are left in the resin composition layer, and only the substrate is peeled off from the carbon nanotubes.

  Thus, the transfer of the carbon nanotubes from the substrate to the epoxy resin composition layer is completed, and a conductive material using the brush-like carbon nanotubes is obtained. The brush-like carbon nanotubes are in a state of penetrating the epoxy resin composition layer, and are reliably transferred to the epoxy resin composition layer.

  The epoxy resin composition layer at the time of transferring is preferably 50 ° C. or higher and 200 ° C. or lower, more preferably 60 to 160 ° C. This heating is preferably performed by far infrared or electromagnetic induction heating. The heating time may be, for example, 1 to 20 minutes, preferably 3 to 10 minutes. By transferring the carbon nanotubes under this temperature range, the resin composition layer is heated to a temperature having an appropriate flexibility for transfer, and the transferred carbon nanotubes penetrate the resin composition layer. At the same time, the carbon nanotubes can be reliably held in the penetrating state even after the transfer is completed. When the temperature of the epoxy resin composition layer is 50 ° C. or lower, the carbon nanotubes cannot be transferred in a penetrating state. When the temperature is 200 ° C. or higher, the carbon nanotubes are vertically aligned when transferred. It becomes difficult to maintain the state.

Moreover, the carbon nanotube can be reliably penetrated by the resin composition layer by setting the resin composition layer in a B stage state before the heating.

  After transferring the carbon nanotubes to the epoxy resin composition layer, the epoxy resin composition layer is cured by heating or the like, if necessary. Thereby, a carbon nanotube can be reliably fixed in the state which penetrated the resin composition layer.

  The carbon nanotubes are pierced substantially perpendicularly to the surface of the epoxy resin composition layer, and have penetrated through this to reach the opposite surface.

  Finally, an electric double layer capacitor using carbon nanotubes will be described.

In order to construct an electric double layer capacitor using the conductive material produced by the method of the present invention as a polarizable electrode, for example, the carbon nanotubes of one electrode and the carbon nanotubes of the other electrode face each other in a non-contact manner. In addition, carbon nanotubes are impregnated with an electrolytic solution, and the whole is placed in a container.

  Next, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

[Example 1]
(First step)
In FIG. 1a, first, a bisphenol A type solid epoxy resin (AER-6051, manufactured by Asahi Kasei Co., Ltd.), a dicyandiamide as a curing agent, and a phenol novolac modified as a polyfunctional epoxy resin on a substrate (1) made of a polyethylene terephthalate film. Epoxy resin (Dainippon Ink Chemical Co., Ltd., “Epicron N-770”, an epoxy resin composition consisting of methyl ethyl ketone, an organic solvent for dilution, was applied with a doctor blade to a thickness of 10 μm and heated at 150 ° C. for 3 minutes. As a result, the organic solvent was evaporated to form the B-stage epoxy resin composition layer (2).

(Second step)
In FIG. 1b, carbon nanotubes (4) having a diameter of 10 nm, a length of 200 μm, and a spacing of 100 nm between carbon nanotubes are grown on a silicon substrate (3) by a CVD method, using a catalyst particle as a nucleus. Was made.

(Third step)
In FIG. 1c, the substrate with carbon nanotubes (5) and the epoxy resin composition layer (2) are heated to 130 ° C. with far infrared rays, and the substrate with carbon nanotubes (5) is carbonized on the surface of the resin composition layer (2). It pressed from the nanotube front-end | tip, and as shown to FIG. 1 d, the front-end | tip part was inserted in the epoxy resin composition layer (2), and the same composition layer (2) was penetrated. The tip of the carbon nanotube is in contact with the substrate (1).

(4th process)
Next, as shown in FIG. 1e, the silicon substrate (3) was mechanically peeled from the carbon nanotubes (4) so as to leave the carbon nanotubes (4) in the epoxy resin composition layer (2). Thus, the transfer of the carbon nanotubes from the substrate to the epoxy resin composition layer was completed. The carbon nanotube (4) did not remain on the silicon substrate (3), and the carbon nanotube transfer from the silicon substrate (3) to the epoxy resin composition layer (2) could be performed without any problem.

(5th process)
The obtained carbon nanotube-embedded substrate (1) with an epoxy resin composition layer was heated in an oven at a temperature of 150 ° C. to cure the epoxy resin composition layer (2).

(6th process)
After curing, the base material (1) is mechanically peeled from the cured epoxy resin layer (6), and the carbon nanotubes (4) are implanted in the cured epoxy resin layer (6) as shown in FIG. 1f. Sex material (7) was obtained. The carbon nanotube (4) has pierced substantially perpendicularly to the surface of the cured epoxy resin layer (6), and has penetrated through the cured resin layer (6) to reach the opposite surface. It was confirmed.

[Example 2]
(First step)
In FIG. 2, 10 parts by mass of conductive carbon fiber is added to 100 parts by mass of the epoxy resin composition as a conductive filler to the epoxy resin composition used in the first step of Example 1, and the resulting mixture is thickened. The same operation as the 1st process of Example 1 was performed except having applied to the 25-micrometer-thick aluminum foil (8), and forming the epoxy resin composition layer (2).

(2nd to 5th steps)
In the second to fifth steps, the same operations as those in the corresponding steps in Example 1 were performed. The carbon nanotube (4) was pierced substantially perpendicularly to the epoxy resin composition layer (2), and the state of penetrating the resin composition layer (2) was confirmed. As in Example 1, there was no carbon nanotube on the silicon substrate, and carbon nanotube transfer from the silicon substrate to the epoxy resin composition layer (2) could be performed without any problem.

(6th process)
After curing, the aluminum foil (8) was mechanically peeled from the cured epoxy resin layer to obtain a conductive material in which carbon nanotubes were planted in the cured epoxy resin layer. It was confirmed that the carbon nanotube (4) was pierced substantially perpendicularly to the surface of the cured epoxy resin layer, and reached the opposite surface through the carbon nanotube (4).

[Example 3]
The conductive material obtained in Example 1 and Example 2 was used as a polarizable electrode, and the electrolyte used was an ionic liquid tetrafluoroborate N, N-diethyl-N-methyl-N- (2- An electric double layer capacitor was fabricated using a methoxyethyl) ammonium salt (having a potential window up to 5.5V).

  A voltage was applied between the positive electrode and the negative electrode of the electric double layer capacitor, and the reaction current was measured by cyclic voltammetry. As a result, no reaction current was observed in the potential window region up to 3.5 V, and it was found that the electric double layer capacitor can operate in a high voltage region.

[Comparative Example 1]
(First step)
A conductive adhesive using a thermoplastic resin (polyvinyl chloride) as a binder is coated on a base material made of polyethylene terephthalate film to a thickness of 10 μm, the organic solvent is evaporated, and the coating layer is dried. An adhesive layer was formed.

(Second step)
The same operation as in the second step of Example 1 was performed to prepare a substrate with carbon nanotubes.

(Third step)
The substrate with carbon nanotubes was pressed against the conductive adhesive layer from the tip of the carbon nanotubes at room temperature, and the tip was inserted into the conductive adhesive. Thereafter, it took 10 minutes for the conductive adhesive layer to fully cure.

(4th process)
Next, the silicon substrate was mechanically peeled from the carbon nanotubes so as to leave the carbon nanotubes in the conductive adhesive layer. Thus, the transfer of the carbon nanotubes from the substrate to the epoxy resin composition layer was completed. However, some carbon nanotubes remained on the substrate, and transfer did not proceed well.

(5th process)
An attempt was made to mechanically peel the substrate from the substrate with the carbon nanotube transfer conductive adhesive layer, but the conductive adhesive layer was torn. Moreover, although the carbon nanotube pierced substantially perpendicularly to the conductive adhesive layer, it did not reach the opposite surface through the carbon nanotube.

The conductive material produced by the method for producing a conductive material using the carbon nanotube of the present invention is applied as, for example, a polarizable electrode which is a main component of an electric double layer capacitor capable of storing a large amount of electricity. it can.

FIG. 1 a is a cross-sectional view schematically illustrating a first step of the first embodiment. FIG. 1B is a sectional view schematically showing a second step of the first embodiment. FIG. 1c is a cross-sectional view schematically showing a third step of the first embodiment. FIG. 1d is a sectional view schematically showing a third step in the first embodiment. FIG. 1e is a sectional view schematically showing a fourth step in Example 1. FIG. 1 f is a cross sectional view schematically showing a sixth step of Example 1. FIG. 2 is a cross-sectional view schematically showing a first step of the second embodiment. FIG. 3 is a cross-sectional view of the carbon nanotube conductive material described in Patent Document 1. FIG. 4 is a cross-sectional view of the carbon nanotube conductive material described in Patent Document 1. FIG. 5 is a cross-sectional view of the carbon nanotube conductive material described in Patent Document 2. FIG. 6 is a cross-sectional view of the carbon nanotube conductive material described in Patent Document 4.

(1) Base material (2) Epoxy resin composition layer (3) Silicon substrate (4) Carbon nanotube (5) Substrate with carbon nanotube (6) Epoxy resin cured material layer (7) Conductive material (8) Aluminum foil

Claims (5)

A step of forming an epoxy resin composition layer (2) containing a curing agent in a B-stage state on a substrate (1) made of a film, and carbon nanotubes (4) with catalyst particles as nuclei on a substrate (3) A step of producing a carbon nanotube-attached substrate (5) which is grown and substantially vertically aligned on the substrate (3), and the carbon nanotube-attached substrate (5) and the epoxy resin composition layer (2) are 50 ° C. or more and 200 ° C. It heats below, the substrate (5) with a carbon nanotube is pressed on the surface of the resin composition layer (2) from the front-end | tip of a carbon nanotube, a front-end | tip part is inserted in an epoxy resin composition layer (2), and the composition layer ( 2) penetrating the carbon nanotube tips into contact with the base material (1), and then leaving the carbon nanotubes (4) in the epoxy resin composition layer (2). As described above, the step of peeling the substrate (3) from the carbon nanotube (4), the step of curing the epoxy resin composition layer (2) of the obtained base material with carbon nanotube embedded epoxy resin composition layer (1), After the curing, the conductive material (7) in which the base material (1) made of a film is peeled from the cured epoxy resin layer (6) and the carbon nanotubes (4) are planted in the cured epoxy resin layer (6). The carbon nanotube (4) is pierced substantially perpendicularly to the surface of the cured epoxy resin layer (6) and reaches the opposite surface through the cured resin layer (6). and characterized that you have become state, method for producing a conductive material using a carbon nanotube. The epoxy resin composition layer containing a curing agent is a) a polyfunctional epoxy resin having 3 or more epoxy groups in the molecule of 5 to 50 parts by mass with respect to 100 parts by mass of the epoxy resin composition, and b) an epoxy resin composition. 100 parts by mass with respect to 5 to 45 parts by weight of phenoxy resin, synthetic rubber or a derivative thereof from 5 to 50 parts by weight based on c) an epoxy resin composition 100 parts by weight, and d) to the epoxy resin composition 100 parts by weight 5 The method for producing a conductive material using carbon nanotubes according to claim 1, comprising at least one material selected from ˜60 parts by mass of a polyamide resin or a derivative thereof . The method for producing a conductive material using carbon nanotubes according to claim 1, wherein the epoxy resin composition layer further contains a conductive filler . An electric double layer capacitor using the conductive material produced by the method for producing a conductive material according to claim 1 as a polarizable electrode. An electric double layer capacitor, wherein the conductive material produced by the method for producing a conductive material according to claim 1 is a polarizable electrode, and the electrolytic solution is an ionic liquid.

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