JP2018037394A - Conductive laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive laminate which has high electrode reactivity and high conductivity and is excellent in water resistance, and to provide an electrode for electrochemical device.SOLUTION: There are provided a conductive laminate which has a conductive layer containing carbon nanotubes and an acrylic resin on a base material, where a mass ratio (acrylic resin/carbon nanotubes) of the acrylic resin with respect to the carbon nanotubes in the conductive layer is 0.6-2.5; and an electrochemical device using the same which can be utilized as a blood glucose level sensor. Preferably, in the conductive laminate, a thickness of the conductive layer is 10-100 nm. Preferably, the conductive laminate contains a dispersant of carbon nanotubes, where the dispersant is carboxyl methyl cellulose and a salt thereof.SELECTED DRAWING: None

Description

  The present invention relates to a conductive laminate having a conductive layer containing carbon nanotubes on a substrate.

  Carbon nanotubes are known as carbon materials with many excellent properties such as high conductivity, heat resistance, light weight, low thermal expansion, high thermal conductivity, chemical stability, high strength / high elastic modulus, etc. By forming a conductive laminate containing carbon nanotubes on the top, it is expected to be applicable to a wide variety of applications such as electrode sensors, touch panels, transistors, capacitors, battery electrodes, heat dissipation materials, and catalysts. .

  In addition, a biosensor has been proposed that can easily quantify a specific component present in a biological sample or the like without diluting and stirring the sample. As an example, Patent Document 1 discloses a biosensor in which an electrode system is formed on an insulating substrate by a method such as screen printing, and a reaction layer containing an oxidoreductase and an electron mediator is formed on the electrode. ing.

  This biosensor quantifies the substrate concentration in a sample as follows. First, by dropping the sample solution onto the reaction layer of the biosensor, the reaction layer is dissolved, and an enzyme reaction proceeds between the substrate in the sample solution and the oxidoreductase in the reaction layer. Along with this enzymatic reaction, the mediator is reduced. After a certain time, a voltage is applied to the electrode of the sensor to electrochemically oxidize the reduced mediator, and the oxidation current value obtained at this time is measured. Since this current value is directly proportional to the substrate concentration, the substrate concentration in the sample solution can be quantified. Such a biosensor has already been put to practical use as a sensor for measuring glucose concentration in blood.

  Furthermore, Patent Document 2 proposes a biosensor that is used by being embedded in a living body in order to continuously measure the glucose concentration in blood.

Examples of biosensors using carbon nanotubes include an electrode system in which carbon nanotubes are supported on platinum metal (Patent Document 3) and a system in which metal particles are mixed with carbon nanotubes (Patent Document 4). In addition, carbon nanotube and “Teflon” (registered trademark) composites, carbon nanotube paste in mineral oil, and carbon nanotubes carrying platinum nanoparticles applied to electrodes have been reported (Non-Patent Documents 1 to 3). 3).

Japanese Patent Laid-Open No. 3-202864 Special table 2014-516658 gazette JP 2006-292495 A JP, 2014-215150, A

Analytical Chemistry (Anal. Chem) 2003, vol. 75, p. 2075- Electrical Chemistry (2003), Volume 5, p. 689- Analytical Chemistry (Anal. Chem) 2004, 79, p. 1083-

  However, Patent Documents 3 and 4 obtain high electrode reactivity by supporting carbon nanotubes on a platinum electrode or mixing metal particles. These methods require a metal such as platinum and are expensive. In Non-Patent Documents 1 to 3, it is reported that the sensitivity of the biosensor can be improved as compared with the case where no carbon nanotube is used. However, none of the reports has improved the dispersibility of the carbon nanotube, and the sensitivity is also practical. It was significantly lower than the biosensor that was made available. Noble metals such as gold are used as electrodes for biosensors that are already in practical use and have good measurement accuracy.

  In addition, in the case of the usage method described in Patent Document 2, since the electrode of the biosensor is immersed in a body fluid for a long time in a living body, high water resistance is required.

The present invention has the following features in order to solve such problems. That is,
(1) A conductive laminate having a conductive layer containing carbon nanotubes and an acrylic resin on a substrate, wherein the mass ratio of the acrylic resin to the carbon nanotubes in the conductive layer (acrylic resin / carbon nanotube) is 0.6. It is 2.5 or less and the conductive laminated body characterized by the above-mentioned.
(2) The conductive laminate according to (1), wherein the conductive layer contains a carbon nanotube dispersant.
(3) The conductive laminate according to (2), wherein the carbon nanotube dispersant is carboxymethylcellulose and a salt thereof.
(4) The conductive laminate according to any one of (1) to (3), wherein the conductive layer has a thickness of 10 nm to 100 nm.
(5) There is an undercoat layer between the base material and the conductive layer, and the undercoat layer contains a polyester resin and / or a urethane resin. A conductive laminate as described in 1.
(6) The method includes the steps of forming a layer containing carbon nanotubes on a substrate and then forming an overcoat layer containing an acrylic resin on the layer containing carbon nanotubes (1) to (5) The manufacturing method of the electrically conductive laminated body in any one of.
(7) An electrochemical device using the conductive laminate according to any one of (1) to (5).
(8) A blood glucose level sensor using the conductive laminate according to any one of (1) to (5).

  According to the present invention, it is possible to provide a conductive laminate having high electrode reactivity, high conductivity, and excellent water resistance.

It is a conceptual diagram of blood glucose level sensor wiring. It is a conceptual diagram of the cross section of the electrically conductive laminated body of this invention. It is a conceptual diagram of the cross section of the electrically conductive laminated body of this invention which has an undercoat layer. It is an example of cyclic voltammetry. It is an example of a Cole-Cole plot. It is an example of an equivalent circuit.

  Hereinafter, modes for carrying out the invention will be described.

[Conductive laminate]
The conductive laminate of the present invention has a conductive layer containing carbon nanotubes and an acrylic resin on a substrate. FIG. 2 is a conceptual view of a cross section showing an example of the conductive laminate of the present invention. Moreover, you may provide an undercoat layer between a base material and a conductive layer as needed.

[Base material]
The substrate used in the present invention is preferably a polymer compound in order to achieve the purpose of mass production at low cost, but is not particularly limited, and glass, quartz, sapphire, silicon, metal, etc. You can choose from a wide range. Examples of the polymer compound include polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, polyether ester, polyvinyl chloride, polyvinyl alcohol, poly ( Examples thereof include (meth) acrylic acid ester, acetate type, polylactic acid type, fluorine type, and silicone type. Further, these copolymers, blends, and further crosslinked compounds can be used.

  Further, among the above-mentioned polymer compounds, those composed of polyester, polyimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, poly (meth) acrylic acid ester, etc. are preferable, and comprehensive consideration is given to workability and economy. Then, a synthetic resin made of polyester, particularly polyethylene terephthalate is preferably used. These base materials may be subjected to various pretreatments such as UV ozone treatment and lamination of an undercoat layer as long as the spirit of the invention is not impaired.

  In addition, if a base material is a film, since a flexible conductive laminated body can be obtained and it can be used for the curved surface part of an electronic device, or it can be used for the electronic component which needs a bending, it is preferable. Furthermore, it is preferable to use a film wound in a roll shape because the conductive laminate of the present invention is continuously produced by roll-to-roll, and there is a merit in terms of cost. In particular, it is preferable to use a polyester film as the film.

  Moreover, when using as a blood glucose level sensor, in order to improve the visibility of blood, it is preferable to use a white base material. White refers to a color defined by JIS L1015 (2010), which is defined by whiteness measured by the Hunter method, and exhibits a value of at least 70%, preferably 90% or more. The thickness of the substrate is preferably in the range of 1 μm to 500 μm, more preferably in the range of 30 μm to 300 μm, and still more preferably in the range of 50 μm to 250 μm from the viewpoints of handling and flexibility.

[Surface hydrophilization]
In the present invention, as described later, it is preferable to apply a coating composition containing an aqueous solvent (hereinafter sometimes referred to as an aqueous undercoat solution) onto a substrate. In order to improve the coatability (coating without repelling) of the water-based undercoat solution, physical treatment such as corona treatment, plasma treatment, flame treatment, etc. as chemical methods such as corona treatment, plasma treatment, flame treatment, etc. It is preferable to carry out an automatic treatment. Of these, corona treatment and plasma treatment are preferred. These treatments are preferable because, for example, the substrate surface water contact angle can be set to 5 ° to 55 °, and the aqueous undercoat solution can be efficiently applied to the substrate.

[Undercoat layer]
In order to improve the coating property of the carbon nanotube dispersion on the base material and to improve the adhesion between the conductive layer containing carbon nanotubes and the base material, it is preferable to provide an undercoat layer on the base material. Moreover, it is preferable that an undercoat layer contains the organic binder mentioned later. Details of the undercoat layer will be described below.

(1) Wetting tension, thickness and roughness of undercoat layer The undercoat layer preferably has a wetting tension of 76 mN / m or more and 105 mN / m or less as defined in ISO8296 (2003). By setting the wetting tension to 76 mN / m or more, it is preferable that when the carbon nanotube dispersion liquid is applied on the undercoat layer, it is difficult to repel the coating and the carbon nanotube dispersion liquid can be uniformly applied. . Also, if the wetting tension of the undercoat layer is 105 mN / m or less, coating unevenness due to spreading of the coating liquid during coating and coating unevenness affected by wind during drying are less likely to occur, and the carbon nanotube dispersion liquid It is preferable because it can be applied uniformly. From the viewpoint of uneven coating, the wetting tension is preferably 76 mN / m or more and 105 mN / m or less, and more preferably 76 mN / m or more and 90 mN / m or less.

  The wetting tension of the undercoat layer can be increased by increasing the copolymerization amount of the hydrophilic functional group contained in the organic binder in the coating composition forming the undercoat layer or by increasing the thickness of the undercoat layer. Can be bigger. Therefore, the wetting tension of the undercoat layer can be appropriately adjusted depending on the copolymerization amount of the hydrophilic functional group contained in the organic binder, the type of the hydrophilic functional group, and the thickness of the undercoat layer.

  The thickness of the undercoat layer can be arbitrarily set as long as the conductive laminate does not easily cause a phenomenon such as curling, and the wettability of the surface of the undercoat layer is within the preferable wet tension range. .

(2) Organic Binder In order to improve the adhesion between the conductive layer containing carbon nanotubes and the substrate, the undercoat layer preferably contains an organic binder. The organic binder is more preferably a thermoplastic resin having a glass transition point of 70 ° C. or lower because adhesion between the base material and the undercoat layer is improved and formation of the upper layer in the process is easy. Examples of the organic binder include urethane resin, phenol resin, silicon resin, nylon resin, polyethylene resin, polyester resin, olefin resin, vinyl resin, and cellulose resin.

  Among these, it is preferable that the undercoat layer contains a polyester resin and / or a urethane resin from the viewpoints of improving the adhesion between the base material and the undercoat layer and the water resistance and chemical resistance of the undercoat layer. The undercoat layer may contain a polyester resin or a urethane resin, or may contain both a polyester resin and a urethane resin. More preferably, the urethane resin is a urethane resin obtained by polymerizing polyester polyol and isocyanate. As the above polyester resin, “Pesresin” (registered trademark) series manufactured by Takamatsu Yushi Co., Ltd. and “Plus Coat” (registered trademark) series manufactured by Kyoyo Chemical Industry Co., Ltd. are preferably used. The “Superflex” (registered trademark) series manufactured by Daiichi Kogyo Seiyaku Co., Ltd. is preferably used.

(3) Particles In the present invention, the undercoat layer preferably contains particles. By including the particles, the coating property of the carbon nanotube dispersion liquid can be further improved. Moreover, since antiblocking property can also be provided to an undercoat layer, it is preferable. That is, when the conductive laminate is produced by roll-to-roll, it may be necessary to wind up the substrate on which the undercoat layer is formed after the undercoat layer is formed. In that case, the undercoat layer may contain particles. The undercoat layer is preferred because it is difficult to block.

  The content of the particles is preferably 5% by mass or more and 95% by mass or less when the entire undercoat layer is 100% by mass. When it is less than 5% by mass, the surface of the undercoat layer is insufficiently uneven, and the anti-blocking property may not be exhibited. On the other hand, if it exceeds 95% by mass, the particles may be excessive with respect to the binder, and the particles may fall off. A preferable range of the particle diameter is 5 nm to 500 nm. More preferably, they are 15 nm-100 nm, More preferably, they are 15 nm-40 nm. In addition, a particle diameter here means the average particle diameter measured by the dynamic light scattering method.

The particles used in the present invention may be organic particles, inorganic particles, or both. Examples of the composition of inorganic particles that can be used in the present invention include silica, colloidal silica, alumina, ceria, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, and various metal oxides. Fine particles are preferred. In particular, inorganic colloidal particles are preferable from the viewpoint of dispersibility in a polyester resin having a hydrophilic functional group, and colloidal silica is particularly preferable. Furthermore, colloidal silica in which -SiOH groups and -OH ^- ions are present on the surface of colloidal silica, an electric double layer is formed in a negatively charged state, and is dispersed and stable in the solvent by electrostatic repulsion between colloidal silica. It is preferable that -SiOH groups and -OH colloidal silica surface ^- ion present, the electric double layer is formed at the charged state negatively, as the colloidal silicas dispersed stably in a solvent by the electrostatic repulsion between the colloidal silica, “Snowtex” (registered trademark) series manufactured by Nissan Chemical Industries, Ltd., “Cataloid” (registered trademark) series manufactured by JGC Catalysts & Chemicals, Inc., and the like are preferably used.

  As a composition of the organic particle which can be used for this invention, the particle | grains which use acrylic acid, styrene resin, thermosetting resin, silicone, an imide compound etc. as a structural component are mentioned, for example. Particles (so-called internal particles) that are precipitated by a catalyst or the like added during the polyester polymerization reaction are also preferably used. In particular, styrene / acrylic particles are preferable from the viewpoints of dispersibility in a polyester resin having a hydrophilic functional group and versatility. As the styrene / acrylic particles stably dispersed in the liquid, “Movinyl” (registered trademark) 972 manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is preferably used.

(4) Method for forming undercoat layer The organic binder described above and, if necessary, a coating composition containing an additive and a solvent are applied onto a substrate, and the solvent is dried as necessary. An undercoat layer can be formed on the material.

  Moreover, it is preferable to use an aqueous solvent as a solvent for the coating composition. A coating composition using an aqueous solvent is sometimes referred to as a coating composition containing an aqueous solvent. By using an aqueous solvent, rapid evaporation of the solvent in the drying step can be suppressed, and not only a uniform undercoat layer can be formed, but also the environmental load is excellent.

  Here, the aqueous solvent is soluble in water such as water or water and alcohols such as methanol, ethanol, isopropyl alcohol and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol and propylene glycol. A certain organic solvent is mixed in an arbitrary ratio.

  The coating composition can be applied on the substrate by known wet coating methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, gravure coating, slot die coating, roll coating, bar coating, and screen printing. Inkjet printing, pad printing, and other types of printing can be used. Further, a dry coating method may be used. As the dry coating method, physical vapor deposition such as sputtering or vapor deposition, chemical vapor deposition, or the like can be used. Moreover, application | coating may be performed in multiple times and it may combine two different types of application | coating methods. Preferred coating methods are gravure coating, bar coating, and slot die coating, which are wet coatings.

  After the application step, the dispersion medium is removed from the undercoat paint containing the dispersant applied in the drying step. Solvent removal methods include convection hot-air drying where hot air is applied to the substrate, radiant heat drying where the substrate absorbs infrared rays by radiation from an infrared drying device, and heats and heats to dry. It is possible to apply conductive heat drying that is heated and dried by heat conduction. Of these, convection hot air drying is preferred because of its high drying rate.

  In the following, a film having an undercoat layer formed on a substrate may be referred to as an undercoat laminated film.

[Conductive layer]
The “conductive layer” in the present invention is a layer containing carbon nanotubes and an acrylic resin. The thickness of the conductive layer is preferably 10 nm or more and 100 nm or less. From the viewpoint of conductivity and weather resistance, the thickness is more preferably 15 nm or more and 50 nm or less.

  The mass ratio of the acrylic resin to the carbon nanotubes in the conductive layer (acrylic resin / carbon nanotube) is preferably 0.6 or more and 2.5 or less, and more preferably 0.8 or more and 1.7 or less. If the mass ratio of the acrylic resin to the carbon nanotube is 0.6 or more, the carbon nanotube is fixed to the base material by the acrylic resin, and the adhesion strength and water resistance of the conductive layer are favorable, which is preferable. In addition, if the mass ratio of the acrylic resin to the carbon nanotube is 2.5 or less, the carbon nanotube is exposed on the surface of the conductive layer. Therefore, when used as a biosensor, a good electrode reaction is likely to come into contact with the electrolyte. This is preferable because it occurs.

[Method for producing conductive laminate]
In producing the conductive laminate, it is preferable to form a layer containing carbon nanotubes on a substrate and then form an overcoat layer on the layer containing carbon nanotubes. A combination of the layer containing carbon nanotubes and the overcoat layer is the conductive layer in the present invention. By forming the layer containing carbon nanotubes first, it is possible to form a layer containing carbon nanotubes with a dense network structure in which the number of contacts between the carbon nanotubes is large. Thereafter, by forming an overcoat layer, the conductive layer can be formed while maintaining a dense network structure of carbon nanotubes, which is preferable because a conductive layer having a small surface resistance value can be formed. When a layer containing carbon nanotubes and a resin constituting the overcoat layer is formed on the substrate at one time, the number of contact points between the carbon nanotubes tends to be smaller than in the above method. In addition, when the overcoat layer is not provided, the carbon nanotubes are not fixed by the resin, so the adhesion between the carbon nanotubes and the substrate is low, and the conductive layer surface layer is physically rubbed or immersed in water, etc. In some cases, carbon nanotubes may fall off the substrate.

  Note that since the overcoat layer penetrates into the carbon nanotube-containing layer and is mixed with the carbon nanotube to form a conductive layer, there may be no clear interface between the carbon nanotube-containing layer and the overcoat layer.

[carbon nanotube]
In the present invention, the conductive layer preferably contains carbon nanotubes. The carbon nanotube used in the present invention is not particularly limited as long as it has a shape obtained by winding one surface of graphite into a cylindrical shape. Single-wall carbon in which one surface of graphite is wound in one layer. Both nanotubes and multi-walled carbon nanotubes wound in multiple layers can be applied. Among them, in particular, carbon nanotubes in which one side of graphite is wound in two layers, particularly two-layer carbon nanotubes are contained in 50 or more in 100, This is preferable because the conductivity and the dispersibility of the carbon nanotubes in the coating dispersion are extremely high. More preferably, 75 or more of 100 are double-walled carbon nanotubes, and most preferably 80 or more of 100 are double-walled carbon nanotubes. In addition, the fact that 50 of the double-walled carbon nanotubes are contained in 100 may be expressed as 50% of the double-walled carbon nanotubes. In addition, the double-walled carbon nanotube is preferable because the original function such as conductivity is not impaired even if the surface is functionalized by acid treatment or the like.

  For example, the carbon nanotube is manufactured as follows. A powdery catalyst in which iron is supported on magnesia is present in the entire horizontal cross-sectional direction of the reactor in a vertical reactor, and methane is supplied in the vertical direction into the reactor. The carbon nanotubes containing single- to five-layer carbon nanotubes can be obtained by contacting the carbon nanotubes at 200 ° C. to produce carbon nanotubes and then oxidizing the carbon nanotubes. Carbon nanotubes can be manufactured and then subjected to an oxidation treatment to increase the ratio of single-layer to five-layer, particularly the ratio of two- to five-layer. The oxidation treatment is performed, for example, by a nitric acid treatment method. Nitric acid is preferred because it acts as a dopant for the carbon nanotubes. A dopant is a substance that gives a surplus electron to a carbon nanotube or takes away an electron to form a hole, and improves the conductivity of the carbon nanotube by generating a carrier that can move freely. Is. Moreover, the number of defects and the number of functional groups in the outer layer of the double-walled carbon nanotube can be increased by performing the oxidation treatment. The nitric acid treatment method is not particularly limited as long as the carbon nanotube of the present invention can be obtained, but is usually performed in an oil bath at 140 ° C. The nitric acid treatment time is not particularly limited, but is preferably in the range of 5 to 50 hours.

[Dispersant]
The layer containing carbon nanotubes preferably contains a carbon nanotube dispersant.

  As the carbon nanotube dispersant, surfactants, various polymer materials (water-soluble polymer materials, etc.) and the like can be used, and ionic polymer materials are preferable because of high dispersibility. Examples of the ionic polymer material include an anionic polymer material, a cationic polymer material, and an amphoteric polymer material. After the carbon nanotube dispersion liquid is applied to the substrate, the dispersant serves as a binder existing between the carbon nanotubes, for example. When measuring the electrochemical characteristics described later, it is measured by immersing in an aqueous solution that is an electrolyte. Since the ionic polymer material has a high affinity with water, the affinity between the hydrophobic carbon nanotube and the aqueous solution can be increased, the electrode reaction area can be increased, and the electrochemical characteristics can be improved. Any kind of ionic polymer material can be used as long as it has a high affinity with water, has a high ability to disperse carbon nanotubes, and can maintain dispersibility. For example, a substance containing carboxymethyl cellulose, a polystyrene sulfonic acid salt, or the like can be used. Among them, a substance containing carboxymethyl cellulose is preferable, and among the substances containing carboxymethyl cellulose, carboxymethyl cellulose and its salt (sodium salt, ammonium salt, etc.) can efficiently disperse carbon nanotubes in the carbon nanotube dispersion liquid. ,preferable.

  In the present invention, when using carboxymethylcellulose and its salt, polystyrenesulfonic acid salt, examples of the cationic substance constituting the salt include alkali metal cations such as lithium, sodium and potassium, calcium, magnesium, barium and the like. Of alkaline earth metal cations, ammonium ions, or organic amines such as monoethanolamine, diethanolamine, triethanolamine, morpholine, ethylamine, butylamine, coconut oil amine, tallow amine, ethylenediamine, hexamethylenediamine, diethylenetriamine, polyethyleneimine Onium ions or these polyethylene oxide adducts can be used, but are not limited thereto.

  The mass ratio of carbon nanotubes to dispersant (dispersant / carbon nanotubes) is preferably in the range of 1.0 to 3.0. If it is less than 1.0, sufficient dispersibility and electrochemical properties may not be obtained, and if it exceeds 3.0, the amount of insulating dispersant becomes excessive, and the value of the surface resistance value described later May rise.

[solvent]
The solvent used in the present invention is preferably water from the viewpoints that the dispersant can be easily dissolved and that the treatment of the waste liquid is easy.

[Carbon nanotube dispersion]
Although the preparation method of the carbon nanotube dispersion liquid used in this invention is not specifically limited, For example, it can carry out in the following procedures. Since the treatment time at the time of dispersion can be shortened, once a dispersion liquid containing carbon nanotubes in a concentration range of 0.003 to 0.15 mass% in the dispersion medium is prepared, dilution is performed to obtain a predetermined concentration. It is preferable to do. In the present invention, the mass ratio of the dispersant to the carbon nanotube (dispersant / carbon nanotube) is preferably 10 or less. Within such a preferable range, it is easy to uniformly disperse, but there is little influence of the decrease in conductivity. The mass ratio is more preferably 0.5 to 9, further preferably 1 to 6, and the mass ratio of 2 to 3 is particularly preferable because high transparent conductivity can be obtained.

  As a dispersing means at the time of preparation, a carbon nanotube and a dispersing agent are mixed and dispersed in a dispersion medium, which is commonly used for coating production (for example, a ball mill, a bead mill, a sand mill, a roll mill, a homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, an ultrasonic device, And mixing using an attritor, a resolver, a paint shaker, and the like. Moreover, you may disperse | distribute in steps, combining these some mixing dispersers. Among them, the method of preliminarily dispersing with a vibration ball mill and then dispersing using an ultrasonic device is preferable because the dispersibility of the carbon nanotubes in the obtained coating dispersion liquid is good.

[Method for producing conductive layer containing carbon nanotube]
In the present invention, the conductive layer containing carbon nanotubes is produced through an application process in which a carbon nanotube dispersion is applied to a substrate, and a drying process in which the dispersion medium is subsequently removed. In the present invention, the method for applying the dispersion on the substrate or the undercoat layer is not particularly limited. Known application methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, gravure coating, slot die coating, bar coating, roll coating, screen printing, inkjet printing, pad printing, other types of printing, etc. Available. Moreover, application | coating may be performed in multiple times and it may combine two different types of application | coating methods. The most preferred application methods are gravure coating, bar coating, and die coating.

  After the coating step, the dispersion medium is removed from the carbon nanotube dispersion containing the dispersant applied in the drying step. Solvent removal methods include convection hot-air drying where hot air is applied to the substrate, radiant heat drying where the substrate absorbs infrared rays by radiation from an infrared drying device, and heats and heats to dry. It is possible to apply conductive heat drying that is heated and dried by heat conduction. Of these, convection hot air drying is preferred because of its high drying rate.

  In the present invention, the conductive layer containing carbon nanotubes refers to a layer containing a solid content containing carbon nanotubes and a dispersant after the dispersion medium is removed from the carbon nanotube dispersion.

[Adjustment of thickness of conductive layer containing carbon nanotubes]
The coating thickness (wet thickness) when applying the carbon nanotube dispersion on the substrate or undercoat layer also depends on the concentration of the carbon nanotube dispersion, so that appropriate surface resistance can be obtained. Adjust it. The coating amount of the carbon nanotube in the present invention can be easily adjusted in order to achieve various uses that require electrical conductivity. For example, the coating amount is ^{1mg / m 2 ~40mg / m 2} .

[Overcoat layer]
Next, an overcoat layer is formed on the layer containing carbon nanotubes. The overcoat layer may penetrate into the layer containing carbon nanotubes and be mixed with the carbon nanotubes to form a conductive layer.

  As the material for the overcoat layer, an acrylic resin excellent in adhesion to the substrate and water resistance is preferably used. Among acrylic resins, it is easy to penetrate into a layer containing carbon nanotubes, and since it exhibits high adhesion and water resistance after being cured, those in which monomers are copolymerized are preferable and have two or more functional groups that contribute to copolymerization. Those obtained by copolymerization of acrylic monomers are more preferred. By using the acrylic resin as the material for the overcoat layer as described above, the conductive carbon nanotube network structure is not easily disturbed and the conductive layer is sufficiently fixed by the acrylic resin. Is formed. In addition, the adhesion between the carbon nanotube and the acrylic resin constituting the overcoat layer is improved. This is preferable because high conductivity and durability can be obtained.

  As the acrylic resin, for example, as a monomer, a copolymer of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate or the like, or a copolymer of urethane acrylate having a urethane skeleton with excellent stretchability as a structure. Is mentioned. Examples of the above-mentioned acrylic resins that are commercially available include “Light Acrylate (registered trademark)” series, “Urethane acrylate” series manufactured by Kyoeisha Chemical Co., Ltd., “Acryt (registered trademark)” series manufactured by Taisei Fine Chemical Co., Ltd. Is mentioned.

[Method for producing overcoat layer]
As a method for producing the overcoat layer, after adjusting the solid content concentration so that the thickness after drying the paint containing the acrylic resin constituting the overcoat layer becomes a desired thickness, the reverse coat method, the gravure coat method It is preferably applied by a rod coating method, a bar coating method, a die coating method, a spray coating method, a spin coating method or the like. The paint containing an acrylic resin can be used in a state where the acrylic resin is dissolved in a solvent or the acrylic resin is dispersed in the solvent. Water, an organic solvent, etc. can be used as a solvent used for the coating material containing the acrylic resin used for the overcoat layer. From the viewpoint of coating suitability, water; alcohol solvents such as isopropyl alcohol and ethanol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as cyclohexanone and methyl ethyl ketone; hydrocarbon solvents such as xylene and toluene are preferable. Used for. These solvents may be used alone or in combination of two or more.

  Various additives can be blended in the coating material containing the acrylic resin used for the overcoat layer, if necessary, as long as the effect of the overcoat layer is not impaired. For example, a catalyst, an antioxidant, a light stabilizer, a stabilizer such as an ultraviolet absorber, a surfactant, a leveling agent, an antistatic agent, a color pigment, or the like can be used.

  Subsequently, it is preferable to remove the solvent by drying the coated film. Here, there is no restriction | limiting in particular as a heat source used for drying, Arbitrary heat sources, such as a steam heater, an electric heater, and an infrared heater, can be used. The heating temperature is preferably 50 to 150 ° C. The heat treatment time is preferably several seconds to 1 hour. Furthermore, the temperature may be constant during the heat treatment, or the temperature may be gradually changed. Moreover, you may heat-process, adjusting humidity in the range of 20 to 90% RH by relative humidity during a drying process. You may perform the said heat processing in the state enclosed with air | atmosphere or inert gas.

  Next, the composition of the coating film may be modified by applying an active energy ray irradiation treatment such as ultraviolet irradiation to the coating film containing the resin after drying as necessary. The ultraviolet treatment may be performed only once or repeated twice or more. From the viewpoint of controlling the composition of the overcoat layer, the oxygen concentration during the ultraviolet treatment is preferably 1.0% by volume or less when the total amount of gas in the system during overcoating is 100% by volume. More preferable is 5% by volume or less. The relative humidity may be arbitrary. In the ultraviolet treatment, it is more preferable to reduce the oxygen concentration using nitrogen gas.

  As the ultraviolet ray generation source, a known source such as a high pressure mercury lamp metal halide lamp, a microwave type electrodeless lamp, a low pressure mercury lamp, a xenon lamp or the like can be used.

Integrated light quantity of ultraviolet irradiation is preferably from ^{50~3,000mJ / cm 2, 100~1,000mJ / cm} 2 is more preferable. The accumulated light amount is preferably 50 mJ / cm ² or more because a desired overcoat layer can be obtained. Further, it is preferable that the integrated light quantity is 3,000 mJ / cm ² or less because damage to the substrate can be reduced.

[Electrochemical properties]
FIG. 1 shows a general configuration of a blood glucose level sensor. The blood glucose level sensor includes a working electrode 101 that generates an oxidation reaction that extracts electrons from glucose, a working electrode 102 that transmits a current generated by the oxidation reaction that occurs at the working electrode 101 to a measurement unit (not shown), and an oxidation current that is generated at the working electrode. On the other hand, it comprises a counter electrode 103 that generates a reduction reaction and maintains the balance of the electrochemical system, a counter electrode conductor 104 that supplies electrons to the counter electrode from a measurement unit (not shown), and a white substrate 105 that supports all the electrodes and conductors.

  The working electrode 101 is generally composed of an enzyme that takes electrons from glucose, a mediator that receives electrons from these enzymes and transmits the electrons to a working electrode conductive layer provided under the working electrode, and a working electrode conductive layer.

  Enzymes act specifically on biological samples such as blood, urine, saliva, sweat, tears, food ingredients and products, and substrates (specific components) derived from the environment, and play a role in oxidizing or reducing them. It is. For example, glucose oxidase, uricase, sarcosine oxidase, lactate oxidase, glucose dehydrogenase, lactate dehydrogenase, alcohol oxidase, alcohol dehydrogenase, cholesterol oxidase, cholesterol dehydrogenase, NADH oxidase, diaphorase, urease, fructose oxidase, fructose dehydrogenase, ascorbate dehydrogenase, etc. Can be used depending on the substance to be measured. Glucose oxidase and glucose dehydrogenase are used for general blood glucose level sensor measurement.

  Examples of mediators include ferricyanide salts, ferrocene and derivatives thereof, methylene blue, benzoquinone and derivatives thereof, naphthoquinone, phenazine methosulfate, and thionine. Particularly preferably used as a blood glucose level sensor is potassium ferricyanide.

  The principle of blood glucose measurement is as follows.

  When the blood to be measured is dropped on the working electrode and the counter electrode, glucose in the blood is deprived of electrons by an enzyme (such as glucose dehydrogenase) that specifically acts only on glucose. The deprived electrons cannot move directly to the electrode, but deliver them to the mediator. At this time, potassium ferricyanide becomes potassium ferrocyanide by the reaction of the following formula (1).

  This potassium ferrocyanide moves to the electrode and delivers electrons to the electrode.

  Through this series of reactions, electrons are taken from glucose on the working electrode 101, and the electrons are transferred to the working electrode conductive layer. Since the current value generated at this time increases or decreases according to the glucose concentration, the glucose concentration in the blood can be measured. The working electrode conducting wire 102 and the counter electrode conducting wire 104 play a role of transmitting current generated at the working electrode and the counter electrode to the measurement unit.

The electrocatalytic activity is generally measured with the following two indices (A, B). In any case, measurement is performed with a three-electrode system in which the working electrode, the counter electrode, and the reference electrode are immersed in an electrolyte solution containing a reaction electrolyte.
A. B. Potential and current density at the oxidation current peak of potassium ferrocyanide when cyclic voltammetry is performed; Charge transfer resistance when performing electrochemical impedance method.
A. About FIG. 3, the example of a measurement using the reaction system of Formula (1) is shown. The oxidation reaction peak 301 shown in the figure indicates an oxidation reaction in which the right side of the formula (1) changes from the right side. The lower the oxidation peak potential 302 and the higher the oxidation peak current density 303, the better the reaction characteristics. In the present invention, when the conductive laminate is immersed in an aqueous solution containing potassium ferrocyanide at a concentration of 5 mmol / l and potassium chloride at a concentration of 0.5 mol / l, the potential on the conductive layer is swept at 50 mV / s. The oxidation peak potential V is preferably in the range of 0.2 V or more and 0.4 V or less on the basis of the silver / silver chloride electrode. More preferably, it is 0.25 to 0.35V. In the electrochemical system defined in the present invention, it is preferable that the oxidation current peak 301 occurs at 0.2 to 0.4 V with the reference electrode Ag / AgCl set to 0 V when swept at 50 mV / s. In this case, the oxidation peak current density I ₁ (303) is preferably 0.50 mA / cm ² or more. If the oxidation peak current density I ₁ (303) is 0.50 mA / cm ² or more, it is preferable because the characteristics are sufficient for sensor applications.

B. Is a system in which a reactant is added, and a voltage at which a reaction of the reactant occurs at the working electrode with reference to the reference electrode, and an AC voltage is applied with a certain width. The real axis component and the imaginary axis component of the impedance obtained by this are plotted. This plot is called a Cole-Cole plot. An example of a Cole-Cole plot is shown in FIG. When the circuit shown in FIG. 5 is assumed to be an equivalent circuit between the electrode and the electrolyte, the charge transfer resistance R _ct 401 shown in FIG. 4 is an index representing the magnitude of the electrode catalyst activity. The charge transfer resistance R _ct 401 is represented by 501 in the equivalent circuit of FIG. 5, and the lower the characteristic, the better the characteristics as a sensor. At this time, the natural potential is based on the silver / silver chloride electrode reference when immersed in an aqueous solution containing potassium ferrocyanide at a concentration of 5 mmol / l, potassium ferricyanide at a concentration of 5 mmol / l, and potassium chloride at a concentration of 0.5 mol / l. The charge transfer resistance is preferably 0.2 Ωcm ^{2 to} 50 Ωcm ² . More preferably, it is 0.4 Ωcm ^{2 to} 40 Ωcm ² . If it is in the range of 0.2 Ωcm ^{2 to} 50 Ωcm ² , it is preferable because it has sufficient characteristics for sensor applications.

[Surface resistance value]
As described above, the working electrode conducting wire 102 and the counter electrode conducting wire 104 play a role of transmitting a current generated in the working electrode and the counter electrode to the measuring unit, and therefore need to have a certain degree of conductivity. In the present application, the surface resistance value is used as an index representing the conductivity of the conductor portion. The required surface resistance value depends on the circuit design of the blood glucose level sensor, but is generally in the range of 1 × 10 ⁰ to 1 × 10 ³ Ω / □.

  The surface resistance value can be adjusted by the coating amount of carbon nanotubes. That is, when the amount of carbon nanotubes applied is increased, the surface resistance value is decreased, and when it is decreased, the surface resistance value is increased. Considering the price of the product, it is preferable to obtain a low surface resistance value with a smaller amount of carbon nanotube coating.

[Usage]
Since the conductive laminate of the present invention has high electrode reactivity and high conductivity, it can be preferably used for an electrochemical device for measuring current. The conductive laminate of the present invention can be particularly preferably used for a blood glucose level sensor.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. The measurement method used in this example is shown below. Unless otherwise specified, when obtaining a numerical value from a measured value, the number of measurements was set to twice, and the average value was adopted as the numerical value.

<Measurement method>
(1) Surface resistance value A probe was brought into close contact with the central portion on the conductive layer side of the conductive laminate having a size of 5 cm × 10 cm, and the surface resistance value was measured at room temperature by a four-terminal method. The used apparatus is a resistivity meter MCP-T360 manufactured by Dia Instruments, and the probe used is a 4-probe probe MCP-TPO3P manufactured by Dia Instruments.

(2) Oxidation peak potential and oxidation peak current density Cyclic voltammetry was performed using the conductive layer of each sample as a working electrode, and the potential and current density at the oxidation current peak of potassium ferrocyanide in the electrolyte were measured. It can be judged that the smaller the potential at the oxidation current peak, the higher the current density, the higher the reaction activity on the surface of the conductive layer.

As an electrolytic solution, an aqueous solution prepared to contain potassium ferrocyanide at a concentration of 5 mmol / l and potassium chloride at a concentration of 0.5 mol / l was used. An Ag / AgCl electrode (manufactured by BAS: RE-1B aqueous reference electrode) was used as the reference electrode, and a Pt electrode (manufactured by BAS: Pt counter electrode 5.7 cm) was used as the counter electrode. The working electrode is prepared by cutting each sample into 10 mm × 20 mm and further bonding the insulating tape with a 3 mm diameter circular hole on the conductive layer to make the working electrode area constant 0.071 cm ^2. Used. Using a potentiostat (Hokuto Denko Co., Ltd .: HZ-7000), cyclic voltammetry measurement was performed under conditions of a sweep rate of 50 mV / s, a potential sweep range of -500 mV to 700 mV with respect to Ag / AgCl, and room temperature. The results of oxidation current peak potential and current at the cycle were adopted. The measured current value was normalized by the electrode area (0.071 cm ² ) and used as the current density. As shown in FIG. 3, the oxidation current peak of potassium ferrocyanide accompanying the above-described formula (1) is confirmed around + 0.2V. The oxidation current peak potential and the oxidation current peak current density were used as indices representing electrode reactivity.

(3) Charge transfer resistance Impedance spectroscopy was performed using the conductive layer of each sample as a working electrode, and the charge transfer resistance of potassium ferrocyanide in the electrolyte was measured. The charge transfer resistance represents the reaction activity.

As an electrolytic solution, an aqueous solution prepared to contain potassium ferrocyanide at a concentration of 5 mmol / l, potassium ferricyanide at a concentration of 5 mmol / l, and potassium chloride at a concentration of 0.5 mol / l was used. The size of the reference electrode, counter electrode, working electrode, and installation method are the same as in item (3). An FRA board was added to a potentiostat (Hokuto Denko Co., Ltd .: HZ-7000), and impedance spectroscopy was performed. The measurement potential was a natural potential, the potential fluctuation was 10 mV, and the frequency was 1 Hz to 10 kHz. The Cole-Cole plot of the impedance spectroscopy obtained in this way was analyzed with analysis software (Hokuto Denko Co., Ltd .: EIS Version 1.0.23) to derive the charge transfer resistance and the electric double layer capacitance. The equivalent circuit used at that time is the same as that shown in FIG. As the fitting method, the Levenberg-Marquard method was used. Search conditions are as follows.
・ Calculation point generation: Mesh fitting calculation: once per search ・ Number of search censoring: 10,000
Absolute tolerance: 1.0 × 10 ⁻¹⁵
Relative tolerance: 1.0 × 10 ⁻¹⁵
・ Maximum number of repetitions: 100
-Difference: forward difference-difference step width: 0.0001.

(4) Water resistance After immersing the conductive laminate in pure water warmed to 37 ° C. for 30 minutes, the conductive layer surface was rubbed 10 times with a finger wearing rubber gloves in the wet state. Thereafter, moisture was wiped off with a waste cloth, and the portion rubbed with a finger was visually observed to determine the peeling of the conductive layer.

(5) Identification of resin and dispersant contained in conductive layer The surface of the conductive layer was measured by the FT-IR-ATR method. The measurement conditions were FTS-55A (FT-IR manufactured by Bio-Rad Digilab), and the ATR crystal was measured using germanium under an infrared incident angle of 60 °.

  When a component could not be specified by the FT-IR-ATR method, the conductive layer was dissolved in deuterated chloroform and measured by nuclear magnetic resonance spectroscopy.

(6) Measurement of mass ratio of carbon nanotube and acrylic resin contained in conductive layer The mass ratio of carbon nanotube and acrylic resin was measured by thermogravimetric analysis (TGA). The sample was installed in a differential thermal analyzer (DTG-60 manufactured by Shimadzu Corporation), and the temperature was raised from room temperature to 900 ° C. at an air supply rate of 50 ml / min and a temperature increase rate of 10 ° C./min. The combustion peak temperature due to heat generation was read from the DTA curve at that time, and the mass change was read from the TG curve to measure the mass ratio of the carbon nanotube to the acrylic resin.

(7) Evaluation of adhesion Adhesion surface of “cello tape” (registered trademark) is attached to the cut conductive layer with 100 mm grid cuts at 1 mm width intervals on the surface of the conductive layer with a cutter knife. I let you. The attached “Cellotape” (registered trademark) was peeled off at a peeling angle of about 90 degrees, and the peeled state of the conductive layer was visually confirmed.

  When the conductive layer remained on the substrate without peeling off the area of 95% or more, the adhesion was considered good.

Example 1
[Preparation of undercoat layer]
An undercoat layer was prepared by the following operation.

  An aqueous dispersion of polyurethane resin (“Superflex 210” solid content concentration: 35 mass%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the resin for the undercoat layer, and an aqueous dispersion of silica particles (“Nissan Chemical Industries, Ltd.“ “Snowtex O” (solid content concentration: 20 mass%) was used as the silica particles contained in the undercoat layer. Superflex 210, Snowtex O and pure water were mixed at a mass ratio of 3.4: 4.0: 12.5 to obtain a coating solution for preparing an undercoat layer having a solid content of 10% by mass. As the substrate, a PET film having a thickness of 188 μm (“Lumirror” (registered trademark) E20 manufactured by Toray Industries, Inc.) was used. Using a UR100 line gravure roll, the rotation ratio of the gravure roll with respect to the line speed was set to 1.5 times, and the coating liquid for the undercoat layer was applied onto the substrate. After coating, the film was dried in a dryer at 125 ° C. for 1 minute. The thickness of the undercoat layer produced by this method was about 600 nm, and the mass ratio of the resin and silica particles in the undercoat layer was 6: 4.

[Preparation of carbon nanotube synthesis catalyst]
About 24.6 g of iron (III) ammonium citrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 6.2 kg of ion-exchanged water. About 1,000 g of magnesium oxide (MJ-30 manufactured by Iwatani Corporation) was added to this solution, and after vigorously stirring for 60 minutes with a stirrer, the suspension was introduced into a 10 L autoclave container. At this time, 0.5 kg of ion exchange water was used as a washing solution. The container was heated to 160 ° C. in a sealed state and held for 6 hours. Thereafter, the autoclave container was allowed to cool, the slurry-like cloudy substance was taken out from the container, excess water was filtered off by suction filtration, and a small amount of water contained in the filtered material was dried by heating in a 120 ° C. drier. While the obtained solid content was refined with a mortar on a sieve, a particle size in the range of 10 to 20 mesh was recovered. The obtained granular catalyst body was introduced into an electric furnace and heated at 600 ° C. for 3 hours in the atmosphere to obtain a catalyst body. The bulk density of the catalyst body was 0.32 g / mL. Further, when the filtrate was analyzed by an energy dispersive X-ray analyzer (EDX), iron was not detected. From this, it was confirmed that the added iron (III) ammonium citrate was supported on the whole amount of magnesium oxide. Furthermore, from the EDX analysis result of the catalyst body, the iron content contained in the catalyst body was 0.39% by mass.

[Production of carbon nanotubes]
Carbon nanotubes were synthesized using the catalyst body. A catalyst body layer was produced by introducing 132 g of the catalyst body onto a quartz sintered plate at the center of the reactor installed in the vertical direction. While heating the catalyst layer until the temperature in the reaction tube reaches about 860 ° C., nitrogen gas is supplied from the bottom of the reactor toward the top of the reactor at 16.5 L / min so as to pass through the catalyst layer. Circulated. Thereafter, while supplying nitrogen gas, methane gas was further introduced at 0.78 L / min for 60 minutes and aeration was performed so as to pass through the catalyst body layer to cause a reaction. The introduction of methane gas was stopped, and the quartz reaction tube was cooled to room temperature while supplying nitrogen gas at 16.5 L / min to obtain a carbon nanotube composition with a catalyst. The catalyst-attached carbon nanotube composition 129 g was stirred in 4.8 mL of a 4.8N hydrochloric acid aqueous solution for 1 hour to dissolve the catalyst metal iron and the carrier magnesium oxide. The resulting black suspension was filtered, and the filtered product was again put into 400 mL of a 4.8N hydrochloric acid aqueous solution to treat with magnesium oxide, and then collected by filtration. This operation was repeated three times to obtain a carbon nanotube-containing composition from which the catalyst was removed.

[Oxidation treatment of carbon nanotubes]
The carbon nanotube composition was added to concentrated nitric acid having a mass of about 300 times (first grade assay 60-61% by mass, manufactured by Wako Pure Chemical Industries, Ltd.) and heated to reflux with stirring in an oil bath at about 140 ° C. for 24 hours. . After heating to reflux, the nitric acid solution containing the carbon nanotube-containing composition was diluted twice with ion-exchanged water and suction filtered. After washing with ion-exchanged water until the suspension of the filtered material became neutral, the carbon nanotube composition was stored in a wet state containing water. When the average outer diameter of the carbon nanotube composition was observed with a high-resolution transmission electron microscope, it was 1.7 nm. The proportion of double-walled carbon nanotubes was 90% by mass, the Raman G / D ratio measured at a wavelength of 532 nm was 80, and the combustion peak temperature was 725 ° C.

[Production of Carboxymethyl Cellulose with Weight Average Molecular Weight: 35,000]
Sodium carboxymethyl cellulose (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 5A, Weight average molecular weight: 80,000, Molecular weight distribution (Mw / Mn): 1.6, Degree of etherification: 0.7) 10% by weight aqueous solution 500 g Was adjusted to pH 2 using primary sulfuric acid (manufactured by Kishida Chemical Co., Ltd.). This container was transferred to an oil bath heated to 120 ° C., and subjected to a hydrolysis reaction for 9 hours with stirring under heating and reflux. After allowing the three-necked flask to cool, the reaction was stopped by adjusting the pH to 10 using a 28 mass% aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.). The weight average molecular weight of the sodium carboxymethylcellulose after hydrolysis was calculated by using a gel permeation chromatography method and comparing it with a calibration curve prepared using polyethylene glycol as a standard sample. As a result, the weight average molecular weight was about 35,000, and the molecular weight distribution (Mw / Mn) was 1.5. The yield was 97% by mass. A dialysis tube (Spectrum Laboratories, Biotech CE dialysis tube, fractionated molecular weight) obtained by cutting 20 g of a 10% by mass aqueous solution of sodium carboxymethylcellulose (weight average molecular weight: 35,000) thus obtained into 30 cm. (3,500-5,000D, 16 mmφ), and this dialysis tube was floated in a beaker containing 1,000 g of ion-exchanged water and dialyzed for 2 hours. Thereafter, the water in the beaker was replaced with 1,000 g of new ion-exchanged water and dialyzed again for 2 hours. After this operation was repeated three times, dialysis was carried out for 12 hours in a beaker containing 1,000 g of fresh ion exchange water. An aqueous sodium carboxymethyl cellulose solution was taken out from the dialysis tube. This aqueous solution was concentrated under reduced pressure using an evaporator and then dried using a freeze dryer. As a result, powdered sodium carboxymethylcellulose was obtained in a yield of 70% by mass. The weight average molecular weight measured by gel permeation chromatography was the same as that before dialysis. In addition, regarding the peak area in the gel permeation chromatography spectrum, the peak area of sodium carboxymethylcellulose was 57% by mass before dialysis, whereas the peak area of ammonium sulfate decreased after dialysis, and the peak of sodium carboxymethylcellulose. The area was improved to 91% by mass.

[Preparation of carbon nanotube dispersion]
The carbon nanotube-containing composition in a wet state (25 mg in terms of dry mass) obtained in the section [Oxidation treatment of carbon nanotubes], 3.5 mass% aqueous solution of sodium carboxymethylcellulose (weight average molecular weight: 35,000) 1.8 g, 13.3 g of zirconia beads (“Traceram” (registered trademark) manufactured by Toray Industries, Inc., bead size: 0.8 mm) were added to the container, and a 28% by mass aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.) The pH was adjusted to 10 using This container was shaken for 2 hours using a vibration ball mill (VS-1 manufactured by Irie Trading Co., Ltd., vibration frequency: 1,800 cpm (60 Hz)) to prepare a carbon nanotube-containing composition paste. The adsorption amount of the dispersant in the obtained carbon nanotube-containing composition paste was 88% by mass, and the average diameter of the carbon nanotube-containing composition was 2.9 μm.

  Next, this carbon nanotube-containing composition paste was diluted with ion-exchanged water so that the concentration of the carbon nanotube-containing composition was 0.15% by mass, and 10 g of the diluted solution was adjusted again to pH 10 with 28% by mass ammonia aqueous solution. did. The aqueous solution was subjected to a dispersion treatment under ice-cooling with an ultrasonic homogenizer (manufactured by Ieda Trading Co., Ltd., VCX-130) output 20 W, 1.5 minutes (2 kW · min / g). The liquid temperature was adjusted to 10 ° C. or lower during dispersion. The obtained liquid was centrifuged at 10,000 G for 15 minutes with a high-speed centrifuge (Tomy Seiko Co., Ltd., MX-300) to obtain 9 g of a carbon nanotube dispersion. The carbon nanotube-containing composition in this dispersion was measured with an atomic force microscope (AFM). The average diameter of the dispersion of the carbon nanotube-containing composition was 1.7 nm, and was isolated and dispersed. The length of the carbon nanotube-containing composition dispersion was 3.9 μm. Thereafter, water was added to the dispersion to prepare a film coating solution so that the concentration of the carbon nanotube-containing composition was 0.06% by mass.

[Production of a layer containing carbon nanotubes]
The film coating solution produced by the production method was applied onto the undercoat layer by a bar coating method and dried to form a layer containing carbon nanotubes. In addition, the count of the bar coat is No. 10, the drying temperature is 100 ° C., and the drying time is 60 seconds.

[Preparation of overcoat layer]
A polyfunctional acrylic monomer (“Light Acrylate DPE-6A” manufactured by Kyoeisha Chemical Co., Ltd.) is diluted with n-propyl alcohol, and a photopolymerization initiator (“IRGACURE” (registered trademark) 184 ”manufactured by BASF) is added to the resin solid content. 5% by mass was added to obtain a coating liquid having a solid content concentration of 0.0625% by mass. This coating solution was applied onto the layer containing carbon nanotubes with a bar coater number 6 and then dried at 125 ° C. for 1 minute using a hot air oven. Further, a UV irradiation apparatus (“I Graphics Co., Ltd.“ ECS-301 ") was used to perform UV irradiation with an irradiation light amount of 400 mJ / cm ² under a nitrogen atmosphere to cure the overcoat layer containing the acrylic resin.

(Example 2)
A conductive laminate was produced in the same manner as in Example 1 except that the bar coater number used for producing the overcoat layer was changed to 8.

(Example 3)
A conductive laminate was prepared in the same manner as in Example 2 except that the solid content concentration of the acrylic monomer used for preparing the overcoat layer was 0.1% by mass.

Example 4
A conductive laminate was produced in the same manner as in Example 2 except that the solid content concentration of the acrylic monomer used for producing the overcoat layer was 0.125% by mass.

(Example 5)
A conductive laminate was produced in the same manner as in Example 2 except that the solid content concentration of the acrylic monomer used for producing the overcoat layer was 0.18% by mass.

(Example 6)
Instead of producing the undercoat layer, a conductive laminate was produced in the same manner as in Example 2 except that the substrate surface was subjected to corona treatment at a treatment strength of 80 W · min / m ² .

(Example 7)
An aqueous dispersion of polyester resin (“Pesresin A647” solid content concentration: 20% by mass manufactured by Takamatsu Yushi Co., Ltd.) is used as the resin for the undercoat layer, and an aqueous dispersion of silica particles (“Snowtex O” manufactured by Nissan Chemical Industries, Ltd.) “Solid content concentration: 20% by mass” was used as the silica particles contained in the undercoat layer. The pesresin A647, Snowtex O, and pure water were mixed at a mass ratio of 9: 1: 10 to obtain a coating solution for preparing an undercoat layer having a solid content of 10% by mass. A conductive laminate was produced in the same manner as in Example 2 except that the undercoat layer coating solution was used.

(Comparative Example 1)
A conductive laminate was produced in the same manner as in Example 1 except that no overcoat layer was produced.

(Comparative Example 2)
A conductive laminate was produced in the same manner as in Example 1 except that the bar coater number used for producing the overcoat layer was changed to No. 4.

(Comparative Example 3)
A conductive laminate was produced in the same manner as in Example 2 except that the solid content concentration of the acrylic monomer used for producing the overcoat layer was 0.25% by mass.

  Table 1 shows the results of evaluation performed on each conductive laminate.

  In the range of the mass ratio of the acrylic resin to the carbon nanotubes (acrylic resin / carbon nanotubes) of the conductive laminates of Examples 1 to 7, good electrochemical characteristics are exhibited as biosensor applications and at the same time high water resistance is exhibited. Since the conductive laminate of Comparative Example 1 does not contain an acrylic resin in the conductive layer, the carbon nanotubes are not fixed to the base material and have poor water resistance. Although the conductive laminate of Comparative Example 2 contains an acrylic resin in the conductive layer, the mass ratio of the acrylic resin to the carbon nanotubes (acrylic resin / carbon nanotubes) is so small that the carbon nanotubes cannot be sufficiently fixed to the base material, resulting in poor water resistance. . On the other hand, in Comparative Example 3, the mass ratio of the acrylic resin to the carbon nanotube (acrylic resin / carbon nanotube) is large, and the acrylic resin covers the carbon nanotube, so that the electrochemical characteristics are deteriorated.

  The present invention can be suitably used, for example, as an electrode for measuring current. In particular, it can be suitably used as an electrode for an electrochemical device or a blood glucose level sensor.

101: Working electrode 102: Working electrode conducting wire 103: Counter electrode 104: Counter electrode conducting wire 105: White substrate 201: Base material 202: Acrylic resin 203: Carbon nanotube 204: Undercoat layer 301: Oxidation current peak 302: Oxidation peak potential 303: Oxidation Peak current density 401: Charge transfer resistance 402: Circumferential vertex 501: Charge transfer resistance 502: Electric double layer capacitance

Claims (8)

  1. A conductive laminate having a conductive layer containing carbon nanotubes and an acrylic resin on a substrate, wherein a mass ratio of acrylic resin to carbon nanotubes (acrylic resin / carbon nanotubes) in the conductive layer is 0.6 or more. 5. A conductive laminate having 5 or less.   The conductive laminate according to claim 1, wherein the conductive layer contains a carbon nanotube dispersant.   The conductive laminate according to claim 2, wherein the carbon nanotube dispersant is carboxymethyl cellulose and a salt thereof.   The thickness of the said conductive layer is 10 nm or more and 100 nm or less, The conductive laminated body in any one of Claims 1-3 characterized by the above-mentioned.   5. The conductive laminate according to claim 1, further comprising an undercoat layer between the base material and the conductive layer, wherein the undercoat layer includes a polyester resin and / or a urethane resin. body.   6. The method according to claim 1, further comprising a step of forming an overcoat layer containing an acrylic resin on the layer containing carbon nanotubes after forming a layer containing carbon nanotubes on the substrate. The manufacturing method of the electroconductive laminated body of description.   An electrochemical device using the conductive laminate according to claim 1.   A blood glucose level sensor using the conductive laminate according to any one of claims 1 to 5.

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