JP2009202379A - Laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive laminated body in which the dependency of surface resistance on a curvature radius is remarkably reduced compared with the conventional one, and having excellent transparency and conductivity. <P>SOLUTION: Disclosed is a laminated body composed of a transparent plastic substrate and a transparent conductive film, having a film composed of at least one layer of carbon nanofiber between the substrate and the transparent conductive film and/or in the transparent conductive film, having a nano-composite laminated structure of the carbon nanofiber and the transparent conductive film, having high visible light transmissivity and conductivity, further having remarkably reduced dependency of surface resistance on a curvature radius, and having high bending resisting performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transparent electroconductive laminate having high transparency, excellent electrical conductivity, and dramatically reduced surface resistance dependence on the radius of curvature.

  A transparent conductive film is a thin film that is transparent to visible light and exhibits conductivity. Used for transparent electrodes such as touch panels and displays. Laminates with a transparent conductive film formed on a transparent plastic substrate are useful industries that use the flexibility of plastic substrates and are used for transparent electrodes that can be mechanically deformed by the pressure applied to the touch panel, and for bending displays. Material.

  The transparent conductive film is generally made of an inorganic material. Typically, a single-layer film type of a semiconductive metal oxide film such as tin-doped indium oxide (ITO, Indium Tin Oxide) and a metal such as silver are used. There is a type that uses a transparent dielectric and a multilayer film, and uses transparency by preventing reflection of metal with visible light due to a light interference effect.

As the single layer film, a film having a thickness of 10 to 300 nm is used according to the necessity of conductivity. The multi-layer film structure is a three-layer film structure such as TiO ₂ / Ag / TiO ₂ , ITO / Ag / ITO, or the five-layer structure such as TiO ₂ / Ag / TiO ₂ / Ag / TiO _{2 on} a glass or plastic film substrate. Created and used industrially. In recent years, a type using a conductive polymer has been tried. However, a transparent conductive film using a metal oxide is most often used because of superiority in environmental durability and electrical characteristics.

  Since these semiconductor inorganic oxides and / or films having an inorganic dielectric film as a multilayer film are used in a thickness of about 10 to 400 nm and are materially brittle, the films are locally acute angles. When the deformation and / or bending is strengthened, the resistance value increases and there is a problem that the electrical reliability is impaired. The problem of the resistance value change with respect to the bending mechanical stress can be determined by the resistance value change when the curvature radius of the film is changed. Numerically, in a laminate in which a transparent conductive film is formed on a general plastic substrate, the resistance value increases rapidly when the radius of curvature is 5 mm or less. For example, a touch panel has been regarded as a serious problem due to durability against deformation with a small curvature radius that occurs locally and repeatedly with a touch pen, and deterioration caused by deformation at the film support end of the transparent conductive film.

  In transparent conductive films using plastics substrates, this problem is that a hard and soft multilayer coating film is provided on the plastics film substrate to form a cushion layer, or a plurality of plastics films are attached via an adhesive. In addition, a method for forming a substrate having a cushioning effect against mechanical stress has been proposed. Although these methods have an improvement effect, the stress relaxation effect of the organic layer is limited, and the effect at a small radius of curvature is limited. In the latter case, a single layer film cannot be used, and there are problems such as complicated processes.

  On the other hand, since a transparent conductive film using an organic conductive polymer has flexibility, the resistance change against bending is improved. As the conductive polymer, polythiophene, polypyrrole, polyaniline and the like have been proposed. However, there is a problem in that there is a limit to the conductivity while maintaining high transparency, and the carrier mobility responsible for conductivity is not sufficient as compared with semiconductors and metal materials, and the response to electrical stimulation is poor. There is also a problem with environmental stability, which is important as an industrial material.

  As a transparent conductive film. A method using a film made of carbon nanotubes has been proposed. One is to mix multi-walled carbon nanotubes with resin, which has transparency and antistatic function. However, multi-walled carbon nanotubes are less transparent when the conductivity is increased, and the conductivity is limited in a film that is nearly transparent, and industrially limited to applications such as antistatic. On the other hand, a single-wall type carbon nanotube film is formed to make a transparent conductive film. However, single-walled carbon nanotubes are difficult to separate from metallic and semiconducting types, and for industrial use, such as semiconductor-type doping and resistance changes due to environmental degradation, there are significant problems other than cost, including reliability. is there. Further, since these films are not continuous films, there is a problem in ensuring uniform conductivity. In response to these current situations, it has been desired to solve a dramatic problem of realizing a transparent conductive film which is excellent in transparency and conductivity and is industrially useful including cost and resistant to minute bending.

JP-A-11-34206 JP 11-198273 A Japanese Patent Laid-Open No. 2-66809 JP-A-2-129808 JP 2008-31205 A US Pat. No. 7,264,990 JP 2006-171336 A

  The problem to be solved is the realization of a transparent conductive film laminate having a nanocomposite laminate structure that is excellent in transparency and conductivity, hardly changes in resistance even at a curvature radius of 5 mm or less, and is resistant to bending.

  The present invention is a laminate composed of a transparent plastic substrate and a transparent conductive film, characterized in that there is a film composed of at least one layer of carbon nanofibers between and / or in the transparent conductive film. To do.

  The laminate of the present invention is a laminate composed of a transparent plastic substrate and a transparent conductive film, and there is a film composed of at least one layer of carbon nanofibers between the substrate and the transparent conductive film and / or in the transparent conductive film. Preferably, it is composed of a nanocomposite laminated structure consisting of a carbon nanofiber film / transparent conductive film from the substrate side, so that it has high transparency, excellent conductivity, and surprisingly low resistance to the radius of curvature. Has a strong advantage.

  The laminate of the present invention is advantageous in terms of cost, and surprisingly, it is a nanocomposite laminate that hardly changes even when the surface resistance is bent to a radius of curvature of 5 mm or less with almost no loss of transparency and conductivity. This is because a structure composed of structures has been found.

  The laminate in the present invention comprises a transparent conductive film, a carbon nanofiber film, and a transparent plastic substrate.

  The transparent conductive film in the present invention may be a thin film having at least one layer made of an inorganic compound, transparent to visible light, and conductive. A metal oxide is used as one form of the transparent conductive film in the present invention. Examples of the transparent conductive film made of the metal oxide include one or more metal oxides from the group consisting of indium, tin, cadmium, zinc, and titanium. These metal oxides are inherently transparent electrical insulators, but when they contain trace amounts of impurities, are slightly oxygen deficient, or are oxides of two or more metals, etc. Become. The metal oxide constituting the transparent conductive film of the present invention must be a semiconductor. Preferred semiconductor metal oxides include, for example, indium oxide, tin oxide, tin-doped indium oxide (ITO), titanium-doped indium oxide, antimony and / or fluorine-doped tin oxide, and a composite oxidation of indium oxide and cadmium oxide. Zinc oxide doped with zinc oxide, aluminum and / or gallium, boron and / or fluorine doped zinc oxide, indium oxide and zinc oxide composite oxide, niobium doped titanium oxide, and / or groups thereof One or more selected complex oxides can be used. In order to obtain sufficient conductivity, the thickness of these metal oxide films is preferably 1 nm or more, and more preferably 7 nm or more. The film thickness is not particularly limited, but 400 nm or less from the film formation speed and cost, and 30 nm or less is particularly preferable for touch panel applications.

  As another form of the transparent conductive film in the present invention, a transparent dielectric and metal multilayer structure is used. The transparent dielectric is not particularly limited as long as it is a solid substance that is transparent to visible light and has a high refractive index, and examples thereof include metal oxides, metal nitrides, metal sulfides, and metal carbides. These metal compounds may be transparent electrical insulators and / or transparent semiconductors. Examples of the metal oxide include one or more metal oxides selected from the group consisting of titanium, zirconium, zinc, indium, tin, cadmium, and silicon. Examples of the metal nitride include nitrides such as silicon and aluminum. Examples of metal sulfides include sulfides such as zinc. Examples of the metal carbide include carbides such as silicon. Further, diamond-like carbon (DLC, Diamond Like Carbon) is also exemplified.

These oxides, nitrides, sulfides and / or carbides may be used alone or as a mixture. The refractive index is preferably 1.6 or more, and particularly preferably 1.8 or more, from the antireflection effect of the metal film. These high refractive index films may be used alone or in a laminated structure. A laminated structure of a high refractive index film and a low refractive index film such as SiO ₂ or MgF may be substantially a high refractive index film.

  The film thickness of these transparent dielectric films is not particularly limited as long as selective light transparency can be realized by the interference effect, but is preferably 10 nm or more and 500 nm or less, particularly preferably 30 nm or more and 200 nm or less.

  The metal film is not particularly limited as long as it is transparent to visible light by being laminated with the dielectric film, has a high reflectance to infrared light, and has a low thermal emissivity, but is made of a group consisting of silver, gold, and copper. One or more metals and / or metal alloys selected from Silver and / or a silver alloy with little light absorption in the visible light wavelength region is preferably used. Examples of silver alloys used for improving environmental resistance include AgCu alloys, AgAu alloys, AgAuCu alloys, AgPd alloys, AgCuPd alloys, and Ag alloys containing rare earth elements such as AgCuNd alloys, and / or Ti alloys thereof. The thing which added metals, such as, is mention | raise | lifted.

  The thickness of these metal films is not particularly limited as long as selective light transparency can be realized by the interference effect, but is preferably 5 nm to 20 nm, particularly preferably 7 nm to 15 nm.

    The structure of the transparent conductive film comprising the multilayer structure of the transparent dielectric and the metal is not particularly limited as long as selective light transmission can be realized by the interference effect, but three layers of dielectric / metal / dielectric from the substrate side. Examples include a film structure, a dielectric / metal / dielectric / metal / dielectric five-layer film structure, and a dielectric / metal / dielectric / metal / dielectric / metal / dielectric seven-layer film structure. The three-layer film structure is preferable because the structure is simple and easy to manufacture, and the five-layer film structure is excellent in selective light permeability and industrial productivity. In particular, the five-layer structure is more preferable because of its excellent industrial productivity and performance. The dielectric may be composed of a laminated film or the like.

  Between these metals and the dielectric film, improvement of metal environmental resistance, reduction of film-forming damage to the metal film surface during dielectric production, improvement of adhesion between metal and dielectric film interface, etc. For the purpose, a very thin film such as Ti or Nichrome may be laminated.

  A transparent plastic substrate is used as the substrate in the present invention. The transparent plastic substrate is not particularly limited as long as it can hold the transparent conductive film, and various polymer moldings can be mentioned.

  The organic polymer compound constituting the polymer molding is not particularly limited as long as it is a transparent organic polymer compound excellent in heat resistance, but usually has a heat resistance of 80 ° C or higher, preferably 100 ° C, Examples include polyimide, polyethersulfone, alicyclic polyolefin resin, polyethylene terephthalate, polyethylene 2,6 naphthalene dicarboxylate, polydiallyl phthalate, polycarbonate, and aromatic polyamide, polyamide, polypropylene, cellulose triacetate, etc. It is done. These can be used as homopolymers, copolymers, alone or as a blend.

  Although the shape of such a polymer molded product is not particularly limited, it is usually preferably in the form of a sheet or film, and in particular, the one on the film can be rolled up and can be continuously produced. preferable. Further, when a film-like material is used, the thickness of the film is preferably 6 μm or more and 500 μm or less, and more preferably 12 μm or more and 200 μm or less.

  The present invention is characterized in that there is a film composed of at least one layer of carbon nanofibers between and / or in the transparent conductive film. The carbon nanofiber in the present invention is a fiber mainly composed of carbon having a diameter of 200 nm or less, a single-walled nanotube having a diameter of 0.1 to 10 nm, and / or a multi-walled nanotube having a diameter of 1 to 100 nm, and / or a diameter of 1 to 100 nm. For example, a multilayer nanofiber made of a plate. These are used as a single species and / or a mixture of two or more species. Since many transparent conductive films used for touch panels have a film thickness of about 20 nm, carbon nanofibers having a diameter of about 0.1 to 30 nm are preferable for this purpose in consideration of the continuity of the transparent conductive film to be laminated. . From the balance of transparency and conductivity, carbon nanotubes are particularly preferable. However, since it is selected according to the purpose of application, it is needless to say that it is not limited to these types. Further, in order to mainly increase the dispersibility and the like on the surface of the carbon nanofiber, chemical and / or physical surface treatment may be performed. In addition, a metal atom such as a doping element and / or a catalyst may be present in the carbon nanofiber.

  In the present invention, it is required that there is a film made of at least one layer of carbon nanofibers between and / or in the transparent plastic substrate. For this purpose, the carbon nanofibers only need to be dispersed in a plane, but in order to uniformly express the nanocomposite effect of the present invention over the entire surface of the plastic substrate, it is less likely to aggregate on the surface, It is preferable that they are uniformly dispersed. The dispersion is realized by a physical formation method such as spraying in the air, deposition of carbon nanofibers on a substrate using a vacuum apparatus or the like, or a method of chemically applying the dispersion. The dispersion may be any solvent that can disperse the carbon nanofibers without condensing, but examples of the solvent include hexane, cyclohexane, heptane, octane, methylcyclohexane, toluene, benzene, xylene, octene, nonene, solvent naphtha, Methanol, ethanol, isopropanol, butanol, pentanol, isopropanol, butanol, pentanol, cyclohexanol, methylcyclohexanol, phenol, cresol, ethyl ether, propyl ether, tetrohydrofuran, N methylpyrrolidone, dioxane, acetone, cyclohexanone, methyl ethyl ketone , Methyl isobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate , Hydrocarbons such as methyl benzoate, glacial acetic acid, chloroform, carbon tetrachloride, trichlene, trichloroethane, chlorobenzene, dibromoethane, methyl cellosolve, cellosolve, cellosolve acetate, alcohols, ethers, esters, carboxylic acids and Examples thereof include organic solvents such as halogenated hydrocarbons and water solvents. In particular, ethanol, isopropanol, butanol, cyclohexanone, N-methylpyrrolidone, and / or an environmentally friendly aqueous solvent are preferably used. These solvents can be used alone or in admixture of two or more if necessary. In some cases, a water-containing solvent may be used. In order to increase dispersibility and the like, for example, a chemical substance such as a surfactant may be added.

  For this purpose, the carbon nanofibers are preferably present in a uniformly dispersed state so that the effects of the present invention can be expressed uniformly on the entire surface of the plastic substrate. The coverage of the carbon nanofiber on the substrate may be selected according to the purpose, but preferably 5% or more, and in order to uniformly reduce local cracks while maintaining high transparency, A coverage of about 20 to 80% is particularly preferred.

In the present invention, a film made of an organosilicon compound is preferably provided as an intermediate layer in contact with the carbon nanofiber and the transparent conductive film in order to increase adhesion between the carbon nanofiber and the transparent conductive film. It is done. The organosilicon compound is a compound represented by the following formula and / or one or more compounds selected from the group consisting of oligomers produced from these hydrolysates.
_{R 1 -N (R 2) -} (CH 2) y -Si (R 3) w - (OR 4) z
In the above formula, R ₁ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a group represented by — (CH ₂ ) _x —N (R ₅ ) —R ₆ . R ₂ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R ₃ and R ₄ are each independently an alkyl group having 1 to 4 carbon atoms, and x and y are each independently 1 to 12 , W represents 0 or an integer of 1 to 2, z represents an integer of 1 to 3, and w + z = 3. In the formula, R ₅ and R ₆ are each independently a group selected from the group consisting of a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Among them, those having excellent durability are preferably those containing an amino group (—NH ₂ ) as a functional group, such as NH ₂ — (CH ₂ ) ₃ —Si— (OCH ₃ ) ₃ , and / or _{NH 3 - (CH 2) 3} -Si- (OC 2 H 5) 3, and _{or, NH 2 - (CH 2)} 2 -NH- (CH 2) 3 -Si- (OCH 3) 3, and or, _{NH 2 - (CH 2) 2} -NH- (CH 2) 3 -Si- (OC 2 H 5) 3, and _{or, NH 2 - (CH 2)} 2 -NH- (CH 2) 3 -Si (CH ₃ )-(OCH ₃ ) ₂ and / or monomers of NH ₂ — (CH ₂ ) ₂ —NH— (CH ₂ ) ₃ —Si (CH ₃ ) — (OC ₂ H ₅ ) ₂ , and / or Oligomer having an association degree of 10 or less produced by hydrolysis Particularly preferred is one or more compounds selected from the group consisting of: The film thickness of the film is not particularly limited, but a film having a monomolecular layer to about 20 nm is used.

  In the laminate of the present invention, a carbon nanofiber film and a transparent conductive film are laminated on a substrate. The configuration of these transparent conductive laminates is not particularly limited as long as the effect of the nanocomposite laminate structure can be exhibited, but the configuration of carbon nanofiber film / transparent conductive film from the substrate side, transparent conductive film (1) / carbon Examples thereof include a configuration of nanofiber film / transparent conductive film (2), a configuration of carbon nanofiber film / transparent conductive film (1) / carbon nanofiber film / transparent conductive film (2), and the like. The structure of the carbon nanofiber film / transparent conductive film from the substrate side is preferable because the structure is simple, easy to manufacture, and excellent in industrial productivity and performance. However, since the position of the carbon nanofiber film is selected according to the purpose of application, it is not limited to these configurations.

  In the laminate of the present invention, the effect of the present invention is realized by a nanocomposite laminate structure of carbon nanofibers and a transparent conductive film. A transparent conductive film made of a metal oxide, a transparent dielectric, and a metal multilayer film is dispersed on the dispersed carbon nanofibers as a nanoscale composite structure, and is expressed by entering and / or covering the fibers. The formation of this structure relieves mechanical stress externally applied to the film, and drastically reduces cracking and peeling at the nano to micron level of the transparent conductive film. The cross-sectional shapes of these films take different forms depending on the diameter of the carbon nanofibers and the two-dimensional and depth overlap of the fibers as the dispersion form. When the diameter of the carbon nanofiber and the film thickness of the transparent conductive film are the same, the surface of the transparent conductive film is related to the shape of the carbon nanofiber, and nanoscale irregularities are formed. Further, when the film thickness of the transparent conductive film is larger than the diameter of the carbon nanofiber, the unevenness is small and smooth. These surface shapes can also have the effect of suppressing disturbances such as surface slippage between the transparent conductive films often caused by devices and the like, and generation of Newton rings due to external light.

  An undercoat layer is added between the substrate and the thin film to increase adhesion, and / or an inorganic and / or organic coating layer is added on the uppermost dielectric to further increase the protective performance. Needless to say, it may be.

  The laminated body of the present invention is used as a single laminated body and / or a composite body obtained by bonding the laminated body to a molded body such as glass or plastics.

  The transparent conductive film used for the laminate of the present invention is formed by various industrial production methods. Although such a manufacturing method is not particularly limited, a method for producing the thin film may be a wet method and / or a physical vapor deposition method (PVD, Physical Vapor Deposition) such as a vacuum deposition method using a vacuum, a sputtering method, And / or chemical vapor deposition (CVD) using a reactive gas. Rather than industrial productivity, metal oxide films and / or metal and dielectric films can be formed continuously and continuously. High-frequency and / or direct current bipolar magnetron sputtering, dual magnetron sputtering, and high-speed film formation. From this point, the direct current magnetron sputtering method is preferable. It goes without saying that depending on the use, a combination with an ion plating or CVD method and / or a wet method may be used in consideration of cost.

  Moreover, the carbon nanofiber film used for the laminate of the present invention is formed by a method of physically forming or a method of chemically applying a dispersion. For the coating of the dispersion, a coating method using a known coating machine such as a spin coater, doctor knife, bar coater, gravure roll coater, curtain coater, knife coater, spray method, dipping method or the like is used. The coating method of the dispersion is preferable as an industrially simple method including cost.

  The laminate of the present invention is a laminate comprising a transparent plastic substrate and a transparent conductive film, and is a nanocomposite in which at least one carbon nanofiber film is provided between and / or in the transparent conductive film. It has a structure, and preferably has a layer formed by hydrolysis of an organosilicon compound between a carbon nanofiber and a transparent conductive film, thereby having excellent transparency and conductivity, and a radius of curvature of surface resistance. The dependency is drastically reduced, and the bending performance is realized.

FIG. 1 shows a cross-sectional view of one embodiment of the laminate of the present invention. The undercoat layer was formed by a spin coater coating method, and the transparent conductive film was formed by a sputtering method using a DC bipolar magnetron sputtering apparatus. The substrate 1 is a polyethylene terephthalate (PET) substrate having a thickness of 75 μm. After installing the substrate in a spin coater device, on one side of the substrate,
_{(C 2 H 5 O) 2} -Si (CH 3) -C 3 H 6 butanol-isopropanol mixed _-NH-C 2 H 4 -NH 3 trimer association of that produced by hydrolysis of the compound represented by the ₂ A 1 cm ³ volume solution of an alcohol solution (solution A) (concentration 0.5% by weight) is applied dropwise onto a substrate rotating at a rotational speed of 6000 rpm and dried at 120 ° C. for 1 minute to form an undercoat layer 2 did. Next, the carbon nanofiber dispersion solution is made to have a concentration of 0.1% by weight with isopropanol, applied dropwise onto the layer 1 of the substrate rotating at 6000 rpm, dried at room temperature for 30 minutes, and carbon nanofibers. A film (referred to as CNF) 3 was formed. The carbon nanofibers are multi-walled carbon nanotubes having a diameter of about 10 to 20 nm and a length of 0.1 to 10 μm. The carbon nanofiber dispersion was mixed with the solution A at a concentration of 0.05% by weight. Next, after the substrate was placed in a vacuum chamber, the vacuum chamber was evacuated to 2.7 × 10 ⁻⁴ Pa. Thereafter, argon gas mixed with 5% oxygen was introduced into the vacuum chamber at a flow rate of 1 sccm or pure Ar gas (purity 99.999%) from the gas inlet at a flow rate of 40 sccm, and the pressure was 5.3 × 10 ⁻¹ Pa. did. An ITO film 4 having a thickness of 20 nm was formed using a target of 10.2 cm in diameter of ITO (SnO ₂ amount 5 wt%) with a sputtering power of 50 W. Next, this sample was heat-treated at 150 ° C. in the atmosphere for 4 minutes. This laminate sample is referred to as Example 1.

  When the surface of the laminate was observed with a Hitachi S-4800 SEM apparatus, the carbon nanofibers were uniformly dispersed on the substrate surface, and an ITO film was formed thereon. Was observed. The area ratio of the carbon nanofibers covering the substrate was confirmed to be about 30%.

  The laminate was irradiated with light from the film surface with a Shimadzu UV-3150 spectrometer, and the light transmittance (%) was measured. The transmittance was measured at normal incidence. This laminate showed 80% light transmission at a wavelength of 550 nm.

  When the surface resistance of the laminate was measured, it showed good conductivity of 300Ω / □.

  In contrast to Example 1 described above, as a comparative example 1, a carbon nanofiber film was not formed on a polyethylene terephthalate film substrate having the same thickness, and an ITO film was directly formed to a thickness of 20 nm and heat-treated under the same conditions as in Example 1. . The sample had a light transmittance of 80% at a wavelength of 550 nm and a surface resistance of 270Ω / □. This laminate sample is referred to as Comparative Example 1.

  These samples were wound around bars with different radii and the surface resistance change was measured. The results are shown in FIG. When the radius of curvature was 4 mm or less, the resistance of the sample of Comparative Example 1 started to increase, and when the radius of curvature was 2.5 mm, the surface resistance increased about 8 times. In contrast, the surface resistance of the sample of Example 1 did not change. Furthermore, at a curvature radius of 1.5 mm, the surface resistance of the sample of Comparative Example 1 increased about 330 times. In contrast, the sample of Example 1 surprisingly changed little.

  When the surfaces of the sample of Example 1 and the sample of Comparative Example 1 bent twice with a radius of curvature of 1.5 mm were observed with an SEM apparatus manufactured by Hitachi, the ITO film of Comparative Example 1 had a size of submicron to μm. Cracks and film peeling occurred all over the ITO film. In contrast, in the sample of Example 1, changes such as cracking and peeling of the ITO film were hardly observed.

  As is clear from these results, the laminate of the present invention is excellent in transparency and conductivity, and even when the radius of curvature is 5 mm or less, there is almost no resistance change, and it becomes an excellent transparent conductive film that is resistant to bending. I understood. As can be seen from the results of SEM observation, the presence of carbon nanofibers produced a composite effect as a nanocomposite in a transparent conductive film, which surprisingly improved the durability of the transparent conductive film against microbending stress. It was.

  The laminated body of the present invention has a visible light transmittance and surface resistance almost equal to those of a transparent conductive film laminated body conventionally used for industrial use such as a touch panel, and is 300 for bending with a radius of curvature of 5 mm or less. We realized a structure that showed surprising performance with a resistance change of less than a fraction. A laminate having an excellent balance was obtained.

As the substrate, a polycarbonate film having a thickness of 180 μm was used. On one side of the substrate, 0.3% by weight of methanol and ethanol of an oligomer having an association degree of 5 formed by hydrolysis of a compound represented by (C ₂ H ₅ O) ₃ —Si—C ₃ H ₆ —NH ₂ Then, an isopropanol mixed alcohol solution was applied onto the substrate with a bar coater and dried at 120 ° C. for 1 minute to form an undercoat layer. On the undercoat layer, the carbon nanofiber dispersion solution was applied with isopropanol to a concentration of 0.1% by weight with a bar coater, and dried at room temperature for 30 minutes. The carbon nanofibers are made of single-walled carbon nanotubes having a length of 0.1 to 10 μm and a diameter of 1 nm. Next, after the substrate was placed in a vacuum chamber, the vacuum chamber was evacuated to 2.7 × 10 ⁻⁴ Pa. Thereafter, argon gas mixed with 5% oxygen was introduced into the vacuum chamber at a flow rate of 1 sccm or pure Ar gas (purity 99.999%) from the gas inlet at a flow rate of 40 sccm, and the pressure was 5.3 × 10 ⁻¹ Pa. did. An ITO film having a film thickness of 20 nm was formed with a sputtering power of 50 W using a target of ITO (SnO ₂ amount 5 wt%) having a diameter of 10.2 cm. This laminate sample is referred to as Example 2.

  The laminate was irradiated with light from the film surface with a Shimadzu UV-3150 spectrometer, and the spectrum was measured. Transmittance was measured at normal incidence. When the light transmittance was determined, performance with a light transmittance of 80% at a wavelength of 550 nm was obtained. In addition, transparent conductivity with a surface resistance of about 400Ω / □ was exhibited.

As a substrate, a 40 μm thick amorphous polyolefin film made by Nippon Zeon was used. One side of the substrate was coated with a carbon nanofiber dispersion (concentration: 0.5% by weight) using a bar coater. The carbon nanofiber is a multilayer plate-type nanofiber having a diameter of 20 to 100 nm and a length of 0.1 to 1 μm. After the substrate was placed in the vacuum chamber, the vacuum chamber was evacuated to 2.7 × 10 ⁻⁴ Pa. Thereafter, argon gas mixed with 1.8% oxygen was introduced into the vacuum chamber through the gas inlet, and the pressure was set to 5.3 × 10 ⁻¹ Pa. Using an ITO (SnO ₂ 5.0 wt%) target having a diameter of 10.2 cm, an ITO film was formed with a sputtering power of 50 W. Next, the target is an Ag _98.6 Cu _0.8 Nd _0.6 (atomic%) alloy with a diameter of 10.2 cm, and argon gas (purity 99.999%) is introduced to form a gas of 5.3 × 10 ⁻¹ Pa. In an atmosphere, an AgCuNd alloy film was formed with a sputtering power of 50 W. Next, argon gas mixed with 1.8% oxygen was again introduced into the vacuum chamber from the gas inlet, and the pressure was set to 5.3 × 10 ⁻¹ Pa. Using an ITO (SnO ₂ 5.0 wt%) target having a diameter of 10.2 cm, an ITO film was formed with a sputtering power of 50 W. These operations are repeated, and CNF / ITO (60) / AgCuNd (10) / ITO (120) / AgCuNd (10) / ITO (60) are formed on the substrate (however, the unit in nm is shown in parentheses) A multilayer film was formed.

  The laminate was irradiated with light from the film surface with a Shimadzu UV-3150 spectrometer, and the spectrum was measured. Transmittance was measured at normal incidence. When the light transmittance was determined, performance with a light transmittance of 82% at a wavelength of 550 nm was obtained. Further, it exhibited a transparent conductivity with a surface resistance of about 30Ω / □.

  As is clear from this example, the laminate of the present invention has high visible light permeability and excellent conductivity, and the surface resistance has a greatly reduced radius of curvature dependency, is resistant to bending, and has excellent performance. A transparent conductor. In addition, this invention is not restrict | limited by a present Example.

It is explanatory drawing of Example 1 which showed the implementation structure of the laminated body. It is a figure which shows the curvature radius dependence of the surface resistance change of the implementation result of a laminated body, and a comparison result.

Explanation of symbols

1 Substrate 2 Undercoat layer 3 Carbon nanofiber film 4 Transparent conductive film

Claims (8)

  A laminate comprising a transparent plastic substrate and a transparent conductive film, wherein the laminate comprises at least one layer of carbon nanofibers between and / or in the transparent conductive film.   The laminate according to claim 1, wherein the transparent conductive film is made of a metal oxide.   2. The laminate according to claim 1, wherein the transparent conductive film comprises a multilayer film of a transparent dielectric and a metal.   The laminate according to any one of claims 1 to 3, wherein the carbon nanofiber comprises a carbon nanotube.   The laminate according to any one of claims 1 to 3, wherein the carbon nanofiber comprises a multilayer plate type. Between the carbon nanofiber (A) and the transparent conductive film (B), one compound selected from the group consisting of compounds mainly represented by the following formula and / or oligomers produced from these hydrolysates: Or at least a layer (C) produced by hydrolysis of two or more organic silicon compounds, wherein the C layer is in contact with the carbon nanofibers and the transparent conductive film. Laminated body.
_{R 1 -N (R 2) -} (CH 2) y -Si (R 3) w - (OR 4) z
(Where R ₁ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a group represented by — (CH ₂ ) _x —N (R ₅ ) —R ₆ , R ₂ is a hydrogen atom or a carbon atom. R ₁ and R ₄ each independently represents an alkyl group having 1 to 4 carbon atoms, x and y each independently represents an integer of 1 to 12, and w represents 0 or 1 to 2 Wherein z represents an integer of 1 to 3, and w + z = 3, wherein R ₅ and R ₆ are each independently a hydrogen atom or a group consisting of an alkyl group having 1 to 4 carbon atoms. A group selected from:   The laminate according to any one of claims 1 to 6, wherein the laminate comprises a carbon nanofiber film / transparent conductive film from the substrate side.   The laminate according to any one of claims 1 to 7, wherein the laminate is formed using a coating method of a carbon nanofiber dispersion at the time of forming the carbon nanofiber film.

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