JP2019065117A - Transparent conductive film, coating composition for forming transparent conductive film, and method of producing transparent conductive film - Google Patents

Abstract

To provide a transparent conductive film excellent in moist heat resistance and weather resistance, and a coating composition excellent in storage stability for forming the transparent conductive film.SOLUTION: The transparent conductive film formed on one surface of a transparent substrate contains a conductive polymer containing a polythiophene-based compound/polystyrene sulfonic acid, an inorganic binder containing a silane compound, an inorganic acid, and a surface conditioner. The inorganic acid is contained in an amount of less than 30 mass% based on the content of the conductive polymer.SELECTED DRAWING: None

Description

  The present invention relates to a transparent conductive film formed on one surface of a transparent substrate, a coating composition for forming the transparent conductive film, and a method for producing the transparent conductive film.

  Since thiophene-based and aniline-based polymers have excellent stability and conductivity, their use as organic conductive materials is expected. A transparent conductive film in which a conductive polymer obtained by adding a dopant to the above-mentioned polymer to a transparent electrode and an antistatic film used for various devices such as liquid crystal displays and transparent touch panels is used as one of its applications Is used.

  For example, in Patent Document 1, a transparent conductive film is provided on a transparent substrate, and the transparent conductive film contains a conductive polymer and a particulate inorganic binder containing a silane compound, and the conductive As the polymer, a transparent conductive sheet is described, which is disposed between particles of the inorganic binder.

JP, 2016-170914, A

  In recent years, the required performance for transparent electrodes and antistatic films used in various devices has increased, and the heat and humidity resistance and the weather resistance can be further improved even for transparent conductive films obtained by bonding conductive polymers with an inorganic binder. It is required. In particular, since the characteristics of the coating composition for forming the transparent conductive film change in a short time, it is difficult to efficiently manufacture the transparent conductive film excellent in the uniformity of the film thickness.

  The present invention solves the above problems, and the object of the present invention is to provide a transparent conductive film excellent in heat and humidity resistance and weather resistance, and a coating excellent in storage stability for forming the transparent conductive film. It is in providing a composition.

The present invention is formed on one side of a transparent substrate containing a conductive polymer containing polythiophene compound / polystyrene sulfonic acid, an inorganic binder containing a silane compound, an inorganic acid, and a surface control agent. A transparent conductive film,
The inorganic acid provides a transparent conductive film contained in an amount of 30% by mass or less based on the content of the conductive polymer.

  In one embodiment, the transparent conductive film further includes an antioxidant in an amount of 10% by mass or less based on the content of the conductive polymer.

  In one embodiment, the inorganic acid is at least one selected from the group consisting of phosphoric acid, hydrochloric acid and sulfuric acid.

  In one embodiment, the antioxidant is a quinone compound.

  In one embodiment, the conductive polymer is contained in an amount of 1 to 75% by mass based on the total amount of the conductive polymer and the inorganic binder.

The present invention is also a coating composition comprising a conductive polymer containing polythiophene compound / polystyrene sulfonic acid, a silane compound, an inorganic acid, a surface conditioner, and an aqueous solvent,
The inorganic acid provides a coating composition contained in an amount of 30% by weight or less based on the content of the conductive polymer.

  In one embodiment, the coating composition further comprises an antioxidant in an amount of 10% by weight or less based on the content of the conductive polymer.

  In addition, the present invention includes a step of forming a coating film by applying any one of the above-mentioned coating compositions to one surface of a transparent substrate, and forming a film by drying and curing the coating film. Provided is a method of manufacturing a conductive film.

  In one embodiment, the application is performed using a spray coating method.

  According to the present invention, a transparent conductive film excellent in heat and humidity resistance and weather resistance, and a coating composition excellent in storage stability for forming the transparent conductive film are provided.

<Transparent conductive film>
A conductive polymer is a polymer called Conductive Polymers (CPs), and itself exhibits conductivity in a state where a polyradical cationic salt or a polyradical anionic salt is formed by doping with a dopant. It refers to the macromolecules obtained.

  In the present invention, as the conductive polymer, one containing a polythiophene compound and a dopant is used. As the conductive polymer in the present invention, a mixture (also referred to as PEDOT / PSS) containing poly (3,4-ethylenedioxythiophene) as a polythiophene compound and polystyrenesulfonic acid as a dopant can be used. PEDOT / PSS is excellent in conductivity, moist heat resistance and weather resistance and is useful.

  As the inorganic binder, a binder containing a silane compound which has high transparency and can form a particulate inorganic binder is used. The electrical property of the transparent conductive film of the transparent conductive sheet of the present invention can be improved by forming the inorganic binder in the form of particles and arranging the conductive polymer between the particles of the inorganic binder.

  Further, the major axis diameter of the particles of the inorganic binder is preferably 10 nm or more and 300 nm or less, and more preferably 20 nm or more and 200 nm or less. If the major axis diameter of the inorganic binder particles is within the range, the conductive path by the conductive polymer can be formed densely.

  In the present invention, the major axis diameter of the inorganic binder particles is obtained by observing the cross section of the transparent conductive film with a scanning electron microscope to determine the major axis diameter of at least 100 binder particles, and calculating the arithmetic of the major axis diameters. It shall be determined as an average value.

  The conductive polymer is used in an amount of 1 to 75% by mass based on the total amount of the conductive polymer and the inorganic binder. When the amount of the conductive polymer used is less than 1% by mass based on the total amount of the conductive polymer and the inorganic binder, the surface resistance of the transparent conductive film becomes large, and the electrical characteristics deteriorate, and 75 mass When it exceeds 10%, coating film adhesion is reduced. The amount of the conductive polymer used is preferably 5 to 50% by mass, more preferably 10 to 25% by mass, based on the total amount of the conductive polymer and the inorganic binder.

  As the inorganic acid, for example, phosphoric acid, hydrochloric acid, sulfuric acid and the like are used. An especially preferred inorganic acid is phosphoric acid. The inorganic acid is used in an amount of 30% by mass or less based on the content of the conductive polymer. When the amount of the inorganic acid used exceeds 30% by mass based on the content of the conductive polymer, the inorganic acid reacts with the conductive polymer, so that the weather resistance of the transparent conductive film decreases, and the coating composition Storage stability is reduced. The amount of the inorganic acid used is preferably less than 30% by mass, more than 5% by weight and less than 30% by mass, and more preferably 7 to 25% by mass, based on the content of the conductive polymer.

  The transparent conductive film may further contain an antioxidant. By using an antioxidant, the heat and humidity resistance and the weather resistance of the transparent conductive film are improved, and the storage stability of the coating composition is further improved. As an antioxidant, a quinone compound, a nitrosamine compound, a phenolic antioxidant, etc. are used.

Examples of quinone compounds include hydroquinone, methoquinone, methylhydroquinone, 4-tert-butylpyrocatechol tert-butylhydroquinone, 1,4-benzoquinone, dibutylhydroxytoluene, 1,1-diphenyl-2-picrylhydrazyl free radical , Mequinol, phenothiazine, 4-hydroxy TEMPO and the like.
Examples of the nitrosamine compound include N-nitroso-N-phenylhydroxylamine, N-nitroso-N-phenylhydroxylamine aluminum salt, N-nitroso-N-phenylhydroxylamine cerium salt and the like.
Phenolic antioxidants include, for example, 2,6-di-tert-butyl-4-methylphenol, propyl gallate, 2,4,5-trihydroxybutyrophenone nordihydroguayretic acid, butylhydroxyanisole, gallic acid Examples include octyl acid, dibutylhydroxytoluene, dodecyl gallate and the like.

  An especially preferred antioxidant is hydroquinone. The antioxidant is used in an amount of 20% by mass or less based on the content of the conductive polymer. When the amount of the antioxidant used exceeds 20% by mass based on the content of the conductive polymer, the proportion of the inorganic binder decreases and the coating film hardness decreases, so the amount of the antioxidant used is The amount is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, based on the content of the conductive polymer.

  The transparent conductive film may further contain an organic binder. When the transparent conductive film contains an organic binder, the adhesion between the transparent conductive film and the transparent substrate can be improved. In particular, when a flexible substrate such as a plastic film is used as the transparent substrate, it is preferable that the transparent conductive film contains an organic binder from the viewpoint of adhesion between the transparent conductive film and the transparent substrate and followability. .

  Examples of the organic binder include acrylic resin, melamine resin, polyester resin, polyamide resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polyvinylidene fluoride resin, hydroxy Examples include ethyl cellulose, polyvinyl alcohol, polyethylene glycol (PEG), polyethylene oxide, polypropylene oxide, polysaccharides, and other photopolymerizable resins. Moreover, as a use form of an organic type binder, a solvent soluble type or an emulsion type can be used. If the content of the organic binder is too large, the effect of the inorganic binder is reduced, so the content of the organic binder is limited to such a range that the problem does not occur.

  The surface resistance value of the transparent conductive film is preferably 150 to 3000 Ω / □. The smaller the surface resistance, the better the electrical characteristics. The surface resistance value of the transparent conductive film is more preferably 250 to 2000 Ω / □, still more preferably 500 to 1000 Ω / □.

  Although the film thickness of a transparent conductive film is suitably set according to a use, it is usually about 0.01-5 micrometers. If the film thickness is too thin or too thick, it becomes difficult to form a uniform transparent conductive film. The film thickness of the transparent conductive film is preferably 0.05 to 1 μm, more preferably 0.1 to 0.3 μm.

  The haze of the transparent conductive film is preferably 2% or less. The lower the haze value, the higher the transparency. The haze can be measured by a haze meter, for example, "NDH 2000" manufactured by Nippon Denshoku Industries Co., Ltd. The haze of the transparent conductive film is more preferably 1% or less, still more preferably 0.5% or less.

  The total light transmittance of the transparent conductive film is preferably 90% or more. The higher the total light transmittance, the better the optical characteristics. The total light transmittance can be measured by a spectrophotometer, for example, "V-570" manufactured by JASCO Corporation. The total light transmittance of the transparent conductive film is more preferably 93% or more, still more preferably 95% or more.

  The hardness of the transparent conductive film is preferably pencil hardness 2H or more. The pencil hardness is determined based on the measurement method of Japanese Industrial Standard (JIS) K5400. The hardness of the transparent conductive film is more preferably pencil hardness 3 H or more.

  The heat and moisture resistance of the transparent conductive film is determined based on the rate of change of the surface resistance before and after the moist heat test of storing for 240 hours in an environment at a temperature of 85 ° C. and a relative humidity of 85%. The change rate of the surface resistance value before and after the moist heat test is preferably 100% or less.

The weather resistance of the transparent conductive film is determined based on the rate of change of the surface resistance before and after the exposure test stored for 120 hours under irradiation of irradiance 60 W / m ² (wavelength 300 to 400 nm). Ru. The change rate of the surface resistance value before and after the exposure test is preferably 300% or less.

  As the transparent substrate, various transparent materials including, for example, plastic, rubber, glass, ceramics and the like can be used.

<Coating composition for forming transparent conductive film>
The content of the conductive polymer in the transparent conductive film-forming coating composition is 0.01 to 10% by mass based on the entire coating composition. When it is applied so that the surface resistance value is 150 to 3000 Ω / □, the wet film thickness becomes 50 μm or more when the content of the conductive polymer is less than 0.01 mass%, and the film thickness exceeds 10 mass%. Is less than 1 μm, which makes it difficult to control the applied film thickness. The content of the conductive polymer is preferably 0.05 to 0.5% by mass, more preferably 0.08 to 0.3% by mass, based on the entire coating composition.

  The silane compounds undergo hydrolysis and dehydration condensation. The silane compound is preferably an alkoxysilane. Further, as the alkoxysilane, at least one alkoxysilane selected from the group consisting of tetraalkoxysilane, trialkoxysilane, dialkoxysilane and an alkoxysilane oligomer is exemplified.

  Examples of tetraalkoxysilanes include silanes tetra-substituted with an alkoxy group having 1 to 4 carbon atoms such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraiso-propoxysilane, tetra-t-butoxysilane and the like. . As a specific example, "KBE-04" (trade name) manufactured by Shin-Etsu Chemical Co., Ltd., etc. may be mentioned.

  Examples of trialkoxysilanes include tri-substituted alkoxy groups having 1 to 4 carbon atoms such as trimethoxysilane, triethoxysilane, tripropoxysilane, tributoxysilane, triiso-propoxysilane, tri L-butoxysilane, etc. Silane is mentioned.

  Examples of dialkoxysilanes include dimethyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane and the like.

  The alkoxysilane oligomer is a relatively low molecular weight resin having an alkoxysilyl group. As a specific example, “X-40-2308”, “X-40-9225”, “X-40-9226”, “X-40-9238”, “X-40-9247”, manufactured by Shin-Etsu Chemical Co., Ltd., "X-40-9250", "KC-89S", "KR-220LP", "KR-401N", "KR-500", "KR-510", "KR-9218" (trade name), Korkot, Inc. And “ethyl silicate 40”, “ethyl silicate 48”, “methyl silicate 51”, “methyl silicate 53A”, “EMS-485”, “SS 101” (trade names), and the like.

  Also, as alkoxysilane, vinylmethoxysilane, p-styrylmethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane Also, alkoxysilane monomers such as hexyltriethoxysilane, decyltrimethoxysilane and trifluoropropyltrimethoxysilane can be used.

  Also, tetraalkoxysilane and trialkoxysilane can be used in combination.

  When tetraalkoxysilane and trialkoxysilane are used in combination as the alkoxysilane, the molar ratio of tetraalkoxysilane to trialkoxysilane is preferably 9: 1 to 5: 5, more preferably 8: 2 to 2 6: 4. The reason why this molar ratio relationship is preferable is to prevent the reduction of the hardness of the transparent conductive film, further eliminate the risk of the occurrence of cracks in the transparent conductive film due to the change with time, and to adhere to the transparent substrate. It is because it can raise more. It is thought that tetraalkoxysilane acts on expression of high film hardness, and trialkoxysilane acts on crack prevention of a transparent conductive film, and adhesiveness with a transparent base material.

The content of the silane compound in the transparent conductive film-forming coating composition is 0.05 to 10% by mass based on the total coating composition. When the content of the silane compound is less than 0.05% by mass, the pencil hardness decreases, and when it exceeds 10% by mass, the ink storage stability is deteriorated.
The content of the silane compound is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, based on the total coating composition.

  The content of the inorganic acid in the transparent conductive film-forming coating composition is 0.0001 to 0.1% by mass based on the entire coating composition. When the content of the inorganic acid is less than 0.0001% by mass, the surface resistance after the reliability test is increased, and when it is more than 0.1% by mass, the ink storage stability is deteriorated. The content of the inorganic acid is preferably 0.001 to 0.07% by mass, more preferably 0.003 to 0.04% by mass, based on the entire coating composition.

  The content of the antioxidant in the transparent conductive film-forming coating composition is 0.1% by mass or less based on the entire coating composition. When the content of the antioxidant exceeds 0.1% by mass, the pencil hardness decreases. The content of the antioxidant is preferably 0.05% by mass or less, more preferably 0.03% by mass or less, based on the entire coating composition. The coating composition for transparent conductive film formation may not contain an antioxidant.

The content of the organic binder in the transparent conductive film-forming coating composition is 50% by mass or less based on the entire coating composition. When the content of the organic binder exceeds 50% by mass, the surface resistance after the reliability test is increased.
The content of the organic binder is preferably 25% by mass or less, more preferably 10% by mass or less, based on the entire coating composition. The coating composition for forming a transparent conductive film may not contain an organic binder.

  As a surface control agent, a silicon type surface control agent can be used, for example, a siloxane type surface control agent etc. are used. The surface conditioner is used in an amount of 0.01 to 10% by weight based on the total coating composition. By adjusting the amount of the surface conditioner to be in the above range, the thickness of the transparent conductive film, particularly the spray coating, can be made uniform. The amount of the surface control agent to be used is preferably 0.02 to 5% by mass, more preferably 0.05 to 0.3% by mass, based on the entire coating composition.

  An aqueous solvent is a solvent containing water. The aqueous solvent preferably comprises a protic polar solvent and an aprotic polar solvent. By using a protic polar solvent and an aprotic polar solvent in combination, it is possible to obtain a transparent conductive film excellent in transparency at a relatively low drying temperature.

  Examples of protic polar solvents include water, ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol, acetic acid and the like, and aprotic polar solvents Examples of D include dimethylsulfoxide, N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylformamide, acetonitrile, acetone, tetrahydrofuran and the like. Particularly preferred aqueous solvents are those containing dimethyl sulfoxide, water and ethanol.

  Examples of the aprotic polar solvent include dimethyl sulfoxide, N-methyl pyrrolidone, N-ethyl pyrrolidone, N, N-dimethylformamide, acetonitrile, acetone, tetrahydrofuran and the like.

  It is preferable that content of an aprotic polar solvent is 1.0 to 50.0 mass% with respect to the whole solvent. When the content of the aprotic polar solvent is less than 1.0% by mass with respect to the whole solvent, the optical properties of the transparent conductive film are deteriorated, and when it exceeds 50.0% by mass, the heat and moisture resistance of the transparent conductive film is descend.

  The content of the solvent is not particularly limited, but may be 50.0% by mass or more and 99.5% by mass or less with respect to the entire coating composition. The solvent may also contain a nonpolar solvent.

  The coating composition can be produced by appropriately mixing a conductive polymer, a silane compound, an inorganic acid, a surface control agent, an aqueous solvent and the like by a known method. For example, each component is mixed and dispersed by mechanical treatment with media such as ball mill, sand mill, pico mill, paint conditioner or the like, or by medialess treatment by ultrasonic dispersion machine, homogenizer, disper, jet mill etc. Can.

  In addition, the order of addition of each component is not particularly limited, and, for example, a silane compound and an inorganic acid may be added to a solution composed of a conductive polymer and a solvent, or a solution composed of a conductive polymer and a solvent After preparing separately the solution which consists of a silane compound, an inorganic acid, and a solvent, you may mix each solution.

  The solids concentration of the coating composition is preferably at most 3% by weight, based on the total coating composition. When the solid content concentration of the coating composition exceeds 3% by weight based on the entire coating composition, the viscosity of the coating composition becomes high, and as a result of which the application by the spray coating method becomes difficult, the uniformity of the film thickness is excellent. It becomes difficult to form a transparent conductive film. The solid content concentration of the coating composition is more preferably 2.5% by weight or less based on the entire coating composition. The solid content of the coating composition refers to a non-volatile component. The solid content of the coating composition typically includes a conductive polymer, a silane compound, an acid catalyst, an antioxidant and a surface conditioner.

  The viscosity of the coating composition is preferably 20 cps or less. When the viscosity of the coating composition exceeds 20 cps, coating by the spray coating method becomes difficult, and as a result, it becomes difficult to form a transparent conductive film excellent in uniformity of film thickness. The viscosity of the coating composition is more preferably 15 cps or less, more preferably 10 cps or less.

  The storage stability of the coating composition is determined by storing the coating composition at room temperature after the preparation of the coating composition, whereby the coating characteristics (for example, surface electrical resistance, haze, transmittance or pencil hardness) of the transparent conductive film are remarkable. When changed, it is determined based on the storage time of the coating composition. The storage time of the coating composition until the coating properties of the transparent conductive film change significantly is preferably 8 hours or more, more preferably 12 hours or more.

<Formation of transparent conductive film>
The conductive film of the present invention is formed by applying the coating composition of the present invention to a transparent substrate to form a coating, and then drying and curing the above coating to form a film.

  As a coating method of the coating composition, for example, known coating methods such as bar coating method, reverse method, gravure coating method, micro gravure coating method, die coating method, dipping method, spin coating method, slit coating method, spray coating method and the like Can be used. It is preferable to use a spray coating method as the method of applying the coating composition. The reason is that by using the spray coating method, even when there is a deviation in the substrate thickness, it is possible to form a coating film having a uniform film thickness, and even to the end of the substrate This is because it is possible to control the film thickness of the coating film and to easily cope with substrates of different dimensions.

  The coating composition of the present invention has a viscosity suitable to be applied by spray coating. Also, the coating composition of the present invention has excellent storage stability. Therefore, the viscosity suitable for application | coating is maintained over the time until it complete | finishes application | coating from being filled to a spray coater, and the coating film with a uniform film thickness can be formed in the whole surface of a base material.

  After the coating composition is spray-coated on the main surface of the substrate, the solvent is removed by heating, and the silane compound is dehydrated and condensed to form a film. If necessary, the coating may be cured by irradiating the coating with UV light or EB light. A coating film is formed using the coating composition of the present invention and the spray coating method, and the film formed by drying and curing the coating film can be referred to as a conductive spray film. The conductive spray coating is a coating having a uniform film thickness without being affected even when the substrate thickness has a deviation, and having a uniform film thickness up to the end of the substrate.

  The heating after application may be performed under conditions that the solvent component of the coating composition evaporates, and is preferably performed at 100 to 150 ° C. for 5 to 60 minutes. By heating, the silane compound becomes a particulate inorganic binder containing polysiloxane by hydrolysis and dehydration condensation reaction, a conductive polymer is disposed between particles of the inorganic binder, and the transparent conductive film is A dimensional conductive path is formed. As a heating method, for example, a hot air drying method, a heating drying method, a vacuum drying method, natural drying and the like can be performed. In addition, if necessary, the coating film may be cured by irradiating the coating film with UV light or EB light to form a transparent conductive film.

  Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples. In the following, "parts" and "%" are based on mass unless otherwise indicated.

<Production of Coating Composition for Forming Transparent Conductive Film>
The following components were prepared and mixed in amounts to achieve the compositions shown in Table 1 to produce a coating composition for forming a transparent conductive film.
(1) Conductive polymer dispersion (made by Heraeus, trade name "Clebios PH 1000", conductive polymer: PEDOT / PSS, solid content concentration: 1.12% by mass, solvent: water)
(2) Silane compound: alkoxysilane (Shin-Etsu Chemical Co., Ltd., trade name "X-40-2308", "KR-220LP", "KR-500")
(3) Aprotic polar solvent (dimethyl sulfoxide)
(4) Acid catalyst (phosphoric acid)
(5) Antioxidant (hydroquinone)
(6) Surface conditioner (polysiloxane type)
(7) Water (8) Protic polar solvent (ethyl alcohol)

<Storage stability>
The prepared coating composition was stored at room temperature for a predetermined time. The coating composition after storage is applied to the surface of an alkali-free glass substrate, dried in an air atmosphere at 120 ° C. to form a film, and the coating film characteristics (surface electrical resistance, haze, transmittance and pencil hardness) are measured. did. For each coating composition, the storage time at which any coating properties changed significantly was determined. The coating composition in which the storage time was less than 8 hours was evaluated as x, in those in which it was 8 to 12 hours, in 〇 and 12 hours or more, the storage stability was evaluated as ◎. The results are shown in Table 1.

<Production of transparent conductive film>
Using a 10 cm square alkali-free glass (total light transmittance: 91.2%) having a thickness of 0.7 mm as a substrate, the coating liquid for forming a transparent conductive film is spray-coated on the entire surface of one side of the substrate. It apply | coated and formed the coating film. As a spray coater, a Nordson spray gun (swirl nozzle, caliber: 1.0 mm) was used. The application conditions were as follows. That is, the spray gun speed is 10 to 1,500 mm / sec, the coating pitch is 2 to 30 mm, the gun height is 1 to 20 cm, and the atomization pressure is 0.01 to 0.5 MPa. Thereafter, it was heated at 120 ° C. for 1 hour. Thereby, the transparent conductive sheet in which the transparent conductive film conductive film was formed in one side was produced.

  Next, each evaluation shown below was performed about the said transparent conductive film. Table 2 shows the composition of the transparent conductive film and the evaluation results.

<Surface resistance>
The surface resistance value (Ω / □) of the transparent conductive film was measured using a resistivity measuring device “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe.

<Film thickness>
The film thickness (μm) of the transparent conductive film is obtained by cutting the conductive film together with the glass substrate and observing the cross section with a scanning electron microscope (SEM, “S-4500” manufactured by Hitachi, Ltd.) to measure the film thickness. did.

<Haze>
The haze (%) of the transparent conductive film was measured using a haze meter "NDH 2000" manufactured by Nippon Denshoku Industries Co., Ltd.

<All light transmittance>
The total light transmittance (%) of the transparent conductive film was measured using a spectrophotometer "V-570" manufactured by JASCO Corporation.

<Pencil hardness>
The pencil hardness of the transparent conductive film was measured using a surface property tester "HEIDON-14DR" manufactured by Shinto Scientific Co., Ltd. based on the measurement method of pencil hardness defined in Japanese Industrial Standard (JIS) K5400.

<Heat and humidity resistance>
First, the initial surface resistance value of the transparent conductive film was measured in the same manner as the evaluation of the electrical characteristics described above. Next, the transparent conductive sheet was placed in a constant temperature and humidity chamber and stored at a temperature of 85 ° C. and a relative humidity of 85% for 240 hours. Subsequently, the surface resistance value of the transparent conductive film of the transparent conductive sheet after storage was measured in the same manner as described above. Finally, the degree of change of the surface resistance value was calculated by the following equation (1).

  Surface resistance change rate (%) = (surface resistance after storage−initial surface resistance) / initial surface resistance (1)

<Weatherability>
First, the initial surface resistance value of the transparent conductive film was measured in the same manner as the evaluation of the electrical characteristics described above. Next, the transparent conductive sheet was placed in a weather meter and stored at an irradiance of 60 W / m ² (wavelength 300 to 400 nm) for 120 hours. Subsequently, the surface resistance value of the transparent conductive film of the transparent conductive sheet after storage was measured in the same manner as described above. Finally, the rate of change of the surface resistance was calculated by the above equation (1).

Claims (9)

A transparent conductive film formed on one surface of a transparent substrate, comprising a conductive polymer containing polythiophene compound / polystyrene sulfonic acid, an inorganic binder containing a silane compound, an inorganic acid, and a surface control agent And
The transparent conductive film, wherein the inorganic acid is contained in an amount of 30% by mass or less based on the content of the conductive polymer.   The transparent conductive film according to claim 1, further comprising an antioxidant in an amount of 10% by mass or less based on the content of the conductive polymer.   The transparent conductive film according to claim 1, wherein the inorganic acid is at least one selected from the group consisting of phosphoric acid, hydrochloric acid and sulfuric acid.   The transparent conductive film according to claim 2, wherein the antioxidant is a quinone compound.   The transparent conductive film according to any one of claims 1 to 4, wherein the conductive polymer is contained in an amount of 1 to 75% by mass based on the total amount of the conductive polymer and the inorganic binder. A coating composition comprising a conductive polymer containing a polythiophene compound / polystyrene sulfonic acid, a silane compound, an inorganic acid, a surface control agent, and an aqueous solvent,
The coating composition, wherein the inorganic acid is contained in an amount of 30% by mass or less based on the content of the conductive polymer.   The coating composition according to claim 6, further comprising an antioxidant in an amount of 10% by mass or less based on the content of the conductive polymer.   A transparent conductive film comprising a step of forming a coating film by applying the coating composition according to claim 6 on one side of a transparent substrate, and forming a film by drying and curing the coating film. Method of producing a membrane   The method for producing a transparent conductive film according to claim 8, wherein the application is performed using a spray coating method.