JP2011249245A - Conductive film manufacturing method and conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive film having an excellent conductivity and light permeability on a substrate even if using a general-purpose polymer substrate such as a PET film, and a method for manufacturing the conductive film readily at low cost and with good productivity.SOLUTION: The conductive film manufacturing method is for manufacturing a conductive film on a substrate by using an organic solvent dispersion material containing conductive particulate. The method includes the steps of coating a substrate with an organic solvent dispersion material, forming a conductive film with a pattern, and irradiating the conductive film with infrared light, and the steps are conducted in this order.

Description

The present invention relates to a method for manufacturing a conductive film and a conductive film. More specifically, the present invention relates to a method for producing a conductive film that can be suitably used for a thin display such as a liquid crystal display, a plasma display, and electronic paper (digital paper), and a touch panel, and a conductive film.

Conductive films have been applied to various electrical devices, and in particular, in recent years, demand for thin displays such as liquid crystal displays, plasma displays, and electronic paper (digital paper) has increased, and they are applied to such applications. As the conductive film, a film excellent in light transmittance and conductivity is particularly demanded, and research and development are being actively conducted.
Currently, indium tin oxide (ITO) is generally used as a light-transmitting conductive film. A conductive film made of indium tin oxide has an excellent balance between light transmittance and conductivity, and is used not only for a normal liquid crystal display or the like but also for a touch panel, for example. However, since rare metals such as indium are expensive and there is a risk of resource depletion, there is a need for a conductive film having light transmittance using a material that is less expensive and less likely to be depleted of resources. By the way. Further, since a sputtering method or the like is usually used for forming an ITO film, there is room for improvement in terms of low productivity.

As a form of the conductive film, a form of a conductive film in which a metal film is formed on a substrate, a form of a conductive film using a light transmissive and conductive material such as indium tin oxide, and a pattern The form of the electroconductive film | membrane which has is mentioned. As a conductive film in which a metal film is formed on a substrate, and a manufacturing method thereof, for example, after a coating liquid containing metal particles is formed on a substrate, heat treatment and ultraviolet light irradiation are performed. A method of forming a metal film (see, for example, Patent Document 1) and metal colloidal particles composed of metal particles and a protective agent having a specific structure are mixed and dispersed in a dispersion medium at a predetermined ratio. Apply the dispersion to the surface of the substrate, keep the substrate coated with metal colloidal particles at room temperature, remove the dispersion medium by natural drying, heat the substrate by infrared irradiation, and hold it for a specified time Discloses a method for forming a metal film on the surface of a substrate (see, for example, Patent Document 2). Also, as a conductive film having a pattern, a conductive pattern is formed by providing a pattern formed by heating and pressurizing a conductive film in which conductive fine particles are dispersed and filled on a flexible film substrate. A film (see, for example, Patent Document 3) is disclosed.

JP 2004-207143 A (first and second pages) JP 2008-194682 A (pages 1 and 2) JP 2008-124446 A (pages 1 and 2)

As described above, various methods have been studied for producing a conductive film at a low cost. Although the metal film manufacturing method described in Patent Documents 1 and 2 is capable of forming a metal film at a heat treatment temperature of 200 ° C. or lower, the heat treatment time is 10 minutes to 2 hours. Therefore, there is room for improvement as a method for manufacturing a conductive film with high productivity. Moreover, since the metal film of patent document 1 and 2 is not formed in the pattern, it was inferior to the light transmittance. The conductive pattern forming film described in Patent Document 3 is manufactured by forming a film while simultaneously applying pressure during heat treatment to form a pattern. By applying pressure, the conductive pattern forming film can exhibit conductivity by heating at a low temperature. It is possible. However, this method requires a device for pressurizing while controlling the pressure, and when pressurizing, there is no sudden pressurization in consideration of the effect on the film to be formed. Since processing is thought to take time, there was room for improvement from the viewpoint of production speed. Furthermore, although the film which formed the pattern was created, there was room for the improvement made into the method which can form a finer pattern.
For these reasons, there has been a demand for a method capable of forming a light-transmitting conductive film more easily and inexpensively at a high production speed. If such a problem can be solved, the material of the substrate can be selected, and a conductive film having light transmittance can be easily produced at low cost on a highly versatile polymer film substrate such as a PET film with good productivity. Since a film can be formed, its technical significance is great.

The present invention has been made in view of the above situation, and even when a general-purpose polymer substrate such as a PET film is used, a conductive film having excellent conductivity and light transmittance on a substrate can be simply and easily formed. An object of the present invention is to provide a conductive film manufacturing method and a conductive film that can be manufactured inexpensively and with high productivity.

The present inventor has been able to use a general-purpose polymer substrate, and variously studied methods for producing a conductive film having excellent conductivity and light transmittance. After the organic solvent dispersion was applied to the substrate, It was found that a conductive film having excellent conductivity and light transmittance can be formed by performing a step of forming a conductive film having a pattern and then performing a step of irradiating infrared rays. According to this method, since a conductive film can be formed without firing at a high temperature and by firing for a very short time, the conductive film is also conductive on a general-purpose polymer substrate having a low heat resistance such as a PET film. The present inventors have found that a conductive film can be formed easily, inexpensively and with good productivity, and have conceived that the above-mentioned problems can be solved brilliantly.

That is, the present invention is a method for producing a conductive film on a substrate using an organic solvent dispersion containing conductive fine particles, wherein the production method has a pattern in which the organic solvent dispersion is applied to the substrate. This is a method for manufacturing a conductive film in which a conductive film having a pattern is formed on a substrate by performing a process of forming a conductive film and a process of irradiating infrared rays in this order.
The present invention is described in detail below.

The method for producing a conductive film of the present invention is a method for producing a conductive film on a substrate using an organic solvent dispersion containing conductive fine particles, and the organic solvent dispersion is applied to the substrate. . In such a method, for example, film formation can be performed easily and at a lower cost as compared with a sputtering method, a plating method, and the like, and manufacturing costs can be reduced and productivity can be improved. it can. Hereinafter, the film of the organic solvent dispersion coated on the substrate is also referred to as “coating film”.

The manufacturing method of the electroconductive film of this invention includes the process of forming the electroconductive film which has a pattern. By including such a step, it is possible to make the manufactured conductive film excellent not only in conductivity but also in light transmittance. Furthermore, it is possible to suppress the shrinkage of the substrate.
The method for forming the conductive film having the pattern is not particularly limited as long as it is a method usually used in manufacturing a film having a pattern. For example, a conductive paste containing a conductive substance is used. A method of screen printing, adding water to an organic solvent dispersion of a conductive material to prepare a W / O type emulsion, and applying the emulsion to a substrate by spreading, spin coating, dipping, etc. A method of evaporating a solvent, a method of forming a pattern by applying pressure while heating a conductive paste filled with metal or semiconductor powder or fine particles, as in Patent Document 3, and a coated organic solvent Examples thereof include a self-assembly method including a step of evaporating the organic solvent while the dispersion is condensed on the surface of the coating film. Among these, the self-organization method is most preferable because a conductive film having a mesh pattern with fine line width and mesh can be formed. As described above, the step of forming the conductive film having a pattern includes a step of evaporating the organic solvent while the organic solvent dispersion applied to the substrate is condensed on the surface of the coating film. This is one of the preferred embodiments. Details of the self-organization method will be described later.

The most preferable method for forming the conductive film having the pattern of the present invention by the self-assembly method is the following in addition to the above-described reason. In the method for producing a conductive film of the present invention, a step of irradiating infrared rays (infrared baking step) is performed after the step of forming a conductive film having a pattern as described later. In the infrared baking step, The energy required for firing is applied to the pattern portion of the conductive fine particles by infrared rays and heated. At that time, since the pattern formed by the self-organization method has fine line width and mesh, heat is easy to escape, and heat conduction to the substrate is sufficiently suppressed even when irradiating strong infrared rays in a short time. Become. This makes it possible to reduce damage to the substrate in the baking process even when using a general-purpose polymer that does not have high heat resistance, such as a PET film, and exhibits sufficient conductivity without causing shrinkage of the substrate. It is possible to form a conductive film. On the other hand, in the manufacturing method of Patent Document 3, since pattern formation and heating are performed in a state where the mold is pressed against the substrate, even if baking is performed by infrared baking, It is difficult to sufficiently suppress heat conduction, and it can be said that it is difficult to reduce damage to the substrate in the firing process.
In addition, when a polymer substrate having a low heat resistance such as a PET film is used as the substrate, when the organic solvent dispersion containing an organic solvent having good wettability is applied, the substrate and the conductive fine particles are more in contact with each other. Furthermore, when the conductive fine particles are heated by infrared rays and the heat is transmitted to the substrate, the substrate is slightly melted locally, and a portion where the conductive fine particles and the substrate are slightly mixed appears. By these, it becomes possible to make a conductive film excellent in adhesion to the substrate.

The manufacturing method of the electroconductive film of this invention includes the process of irradiating infrared rays. In the method for producing a conductive film of the present invention, since the conductive film is formed by infrared irradiation, it is usually necessary to carry out the baking process at a high temperature without performing the baking process at a high temperature. Because it is extremely short compared to the firing time, it not only greatly contributes to shortening the overall production time of the conductive film, it can improve the production speed of the conductive film, but also the influence of heat on the substrate Therefore, a general-purpose polymer film such as a PET film having low heat resistance compared to glass can be used as the substrate.

As described above, the method for producing a conductive film of the present invention includes a step of forming a conductive film having a pattern and a step of irradiating infrared rays, but a step of forming a conductive film having a pattern. After performing, the process which irradiates infrared rays is performed, and the conductive film which has a pattern on a board | substrate is formed.
In addition, the manufacturing method of the electroconductive film of this invention consists of the process of forming the electroconductive film which has a pattern, and the process of irradiating infrared rays (infrared baking process) after apply | coating the organic solvent dispersion to a board | substrate. Other steps may be included as long as they are performed in order, but the step of baking the conductive film preferably includes only the infrared baking step.

The infrared rays irradiated in the infrared irradiation step of the method for producing a conductive film of the present invention include near infrared rays, far infrared rays, etc., and are not particularly limited as long as they are normally classified as infrared rays. Irradiation in the infrared irradiation step described above The conditions may be set as appropriate so that the conductive film can be formed, but it is preferable to irradiate infrared rays of 1 to 2 μm as the peak wavelength. By using an infrared ray of 1 to 2 μm, the coating film is efficiently heated, and a conductive film can be formed in a shorter time. Moreover, as irradiation time, it is preferable that it is 0.1 to 30 second. Even when the irradiation time is in the range of 0.1 to 30 seconds, in the infrared baking in the present invention, a conductive film having a sufficiently excellent conductivity can be produced, and the baking process at a normal high temperature is performed. Since it cannot be performed in such a short time, the effect of the present invention is more remarkably exhibited when the irradiation time is in such a range. More preferably, it is 0.1 to 10 seconds.

The irradiation direction of the infrared rays is not particularly limited as long as the effect of the present invention can be obtained, but it is preferable to irradiate from the side opposite to the substrate of the coating film. By irradiating from the opposite side of the substrate, the coating film is more easily heated than the substrate, and the heat to the substrate is that the heat of the coating film has been conducted. It is possible to suppress as much as possible.

The conductive fine particles used in the present invention generally mean conductive particles having an average particle diameter of 100 μm or less, and the particle diameter of the conductive fine particles is not particularly limited. It is preferable that it is 1 micrometer or less. By setting the average particle diameter to 1 μm or less, the line width of the conductive mesh-like line portion can be reduced, the transparent portion of the transparent conductive film can be widened, and the aperture ratio is improved. Become. Thereby, the transmittance | permeability of a transparent conductive film improves. The average particle diameter of the conductive fine particles is more preferably 500 nm or less, still more preferably 100 nm or less, particularly preferably 50 nm or less, and most preferably 10 nm or less. In particular, by setting the average particle diameter to 10 nm or less, the conductivity of the formed mesh-like line portion having conductivity can be increased. Further, as the particle size distribution, the coefficient of variation is preferably within 30%, more preferably within 20%, and even more preferably within 15%.

The average particle diameter of the conductive fine particles is obtained by a number average particle diameter obtained from a TEM image (transmission electron microscope observation image) or SEM image (scanning electron microscope observation image); a powder X-ray diffraction measurement method. Crystallite diameter: The average radius obtained from the radius of inertia obtained by the X-ray small angle scattering method or the like and the scattering intensity can be used. Especially, it is preferable that it is the number average particle diameter obtained by a SEM image (scanning electron microscope observation image).
The shape of the conductive fine particles is not limited to a spherical shape, and is, for example, an elliptical spherical shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a needle shape, a column shape, a rod shape, a cylindrical shape, a flake shape, a plate shape (for example, a hexagonal plate shape). It can also be suitably used in the shape of a thin piece such as a string or the like.

The conductive fine particles are not particularly limited as long as the conductive fine particles contain a conductive material, and examples thereof include fine particles of metals, conductive inorganic oxides, carbon-based materials, carbide-based materials, and the like. Various metals can be used as the metal, and any form such as a single metal, an alloy, and a solid solution may be used. The metal element is not particularly limited. For example, various metal elements such as platinum, gold, silver, copper, aluminum, chromium, cobalt, and tungsten can be used, but a metal having high conductivity is preferable. The metal having high conductivity preferably contains at least one selected from the group consisting of platinum, gold, silver and copper. Further, the metal is preferably a metal having high chemical stability. For example, when the above-described method for producing a conductive film is used, steps such as dispersing conductive fine particles in an organic solvent and drying the organic solvent are performed. It is preferable that oxidation, corrosion, and the like do not occur for such a process. From the viewpoint of high chemical stability, the metal preferably contains at least one selected from the group consisting of platinum, gold and silver. Among these, it is a preferable form to contain silver from the viewpoint of cost reduction. Examples of the inorganic oxide having conductivity include indium oxides such as indium tin oxide, transparent conductive materials such as zinc oxide oxides, and non-transparent inorganic oxides having conductivity. Examples of the carbon-based material include carbon black. Examples of the carbide-based material include silicon carbide, chrome carbide, and titanium carbide. In addition, as conductive fine particles that can be used, non-conductive fine particles are surrounded by a conductive substance (metal, conductive inorganic oxide, carbon-based material, carbide-based material, etc.) that forms the conductive fine particles. Fine particles (for example, fine particles having a core-shell structure of a core “non-conductive substance” and a shell “conductive substance”) are also preferable. The non-conductive fine particles are not particularly limited, and non-conductive fine particles formed of various substances can be used. As said electroconductive fine particles, these may be used independently and 2 or more types may be used.
Furthermore, as conductive fine particles that can be used, oxide fine particles such as silver oxide and copper oxide are dispersed in an organic solvent and then applied, and then the coating film is placed in a reducing atmosphere to thereby form a metal such as silver and copper. It can also be used after being reduced. That is, the method for producing the conductive film is one of preferred embodiments including a step of reducing the oxide fine particles by coating the oxide fine particles dispersed in an organic solvent and then placing the oxide fine particles in a reducing atmosphere. is there.

The content of the conductive fine particles is preferably 0.05 to 10% by mass with respect to 100% by mass of the organic solvent dispersion. By setting it as such a range, the electroconductive film which has sufficient electroconductivity can be obtained. More preferably, it is 0.1-10 mass% as content of electroconductive fine particles, More preferably, it is 0.2-10 mass%.

The organic solvent dispersion used in the present invention is a dispersion in which conductive fine particles are dispersed in an organic solvent, and may contain substances other than the organic solvent and the conductive fine particles. The organic solvent is not particularly limited, and various organic solvents can be used.
Examples of the organic solvent include aromatic carbon such as benzene hydrocarbon such as benzene, toluene, o-xylene, m-xylene, p-xylene, mixed xylene, ethylbenzene, hexylbenzene, dodecylbenzene, and phenylxylylethane. Hydrogens: paraffinic hydrocarbons such as n-hexane and n-decane, isoparaffinic hydrocarbons such as Isopar (Isopar, manufactured by Exxon Chemical), olefinic hydrocarbons such as 1-octene and 1-decene, cyclohexane, decalin Aliphatic hydrocarbons such as naphthenic hydrocarbons such as: kerosene, petroleum ether, petroleum benzine, ligroin, industrial gasoline, coal tar naphtha, petroleum naphtha, solvent naphtha and other petroleum and coal derived hydrocarbon mixtures; dichloromethane, chloroform , Carbon tetrachloride, 1,2-di Loroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichlorofluoroethane, tetrabromoethane, dibromotetrafluoroethane, tetrafluorodiiodoethane, 1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, Halogenated hydrocarbons such as trichlorofluoroethylene, chlorobutane, chlorocyclohexane, chlorobenzene, o-dichlorobenzene, bromobenzene, iodomethane, diiodomethane, iodoform; esters such as ethyl acetate and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. Ketones; alcohols such as methanol, ethanol, isopropanol, octanol, methyl cellosolve; dimethyl silicone oil, methyl Silicone oils such as E alkenyl silicone oil; fluorine-based solvents hydrofluoroether like; carbon disulfide and the like are preferable. These organic solvents may be used alone or in combination of two or more.
Since such an organic solvent has better wettability than water or the like, by using an organic solvent as the solvent, an organic solvent can be used when a polymer substrate having a low heat resistance such as a PET film is used as the substrate. The conductive fine particles contained in the dispersion are more in contact with the substrate, and it is possible to produce a conductive film that is particularly excellent in adhesion to the substrate.

As the organic solvent, a hydrophobic organic solvent is preferable. By using a hydrophobic organic solvent, water droplets can be taken into the organic solvent dispersion in a more stable form when placed in a humidified atmosphere in the self-assembly method described later. The organic solvent is preferably a nonpolar organic solvent. By being nonpolar, it becomes difficult to dissolve in water, which is a polar molecule, so that the form of water droplets taken into the coating film can be more suitably maintained. Nonpolar organic solvents include aromatic hydrocarbon solvents having about 6 to 10 carbon atoms such as benzene, toluene, xylene, hexane and cyclohexane; halogenated hydrocarbon solvents such as chloroform and dichloromethane; aliphatic hydrocarbon solvents A solvent etc. can be used preferably. Benzene, toluene, hexane, cyclohexane and the like are more preferable from the viewpoint of the evaporation rate of the organic solvent and the solubility of water, that is, from the viewpoint that the evaporation rate is relatively fast, water droplets are easily condensed, and are not easily mixed with water. The organic solvent may be a mixed solvent of a polar solvent and a nonpolar solvent. For example, a mixed solvent of an aromatic hydrocarbon solvent and a ketone solvent, a mixed solvent of an aromatic hydrocarbon and an amide solvent, or the like may be used.

The specific gravity of the organic solvent is preferably not more than the specific gravity of water. When the specific gravity of the organic solvent is larger than the specific gravity of water, water droplets condensed on the surface of the coating film may not be taken into the organic solvent dispersion when the self-assembly method described later is used. Specifically, the specific gravity of the organic solvent is preferably 1.00 or less, more preferably 0.95 or less, and still more preferably 0.90 or less at room temperature (20 ° C.). .

The viscosity of the organic solvent is preferably 2 mPa · s or less at room temperature (20 ° C.). When taking water into the coated organic solvent dispersion, if the viscosity of the organic solvent is too high, water droplets may not be taken in sufficiently.

The organic solvent dispersion preferably contains an infrared absorber. The infrared absorber is not particularly limited as long as it can absorb infrared rays. For example, indium oxides such as indium tin oxide and inorganic oxides such as zinc oxide oxides; azo and aminium Organic dyes such as those based on anthraquinone, cyanine, diimonium, dithiol metal complex, squarylium, naphthalocyanine, and phthalocyanine. When the infrared absorber is coated on the substrate with the organic solvent dispersion, the coating is heated more uniformly when the infrared irradiation process is performed if the conductive fine particles are dispersed as uniformly as possible. Thus, it becomes more suitable as a method for producing a conductive film. On the other hand, in the case of nanoparticles that are too large, there is a possibility that they cannot be dispersed among the conductive fine particles. Therefore, from the viewpoint of dispersibility among conductive fine particles, organic dyes are preferable among the infrared absorbers described above.
These may be used alone or in combination of two or more as the infrared absorber.

Examples of the organic dye include azo, aminium, anthraquinone, cyanine, diimonium, dithiol metal complex, squarylium, naphthalocyanine, and phthalocyanine. Among these, a phthalocyanine type is preferable from the viewpoints of dispersibility in an organic solvent, absorption wavelength, and extinction coefficient. The phthalocyanine compounds described in JP-A No. 2000-26748 are particularly preferable because of excellent dispersibility and absorption characteristics.

The content of the infrared absorber is preferably 0.0001 to 10% by mass with respect to 100% by mass of the organic solvent dispersion. By including an infrared absorber in such a range, when irradiated with infrared rays, a conductive film having sufficient conductivity can be obtained by irradiation in a short time. The content of the infrared absorber is more preferably 0.0005 to 5% by mass.

The organic solvent dispersion preferably contains a fine particle dispersant that promotes dispersion of the fine particles in the organic solvent. By containing the fine particle dispersant, the conductive fine particles can be prevented from aggregating in the organic solvent, and the organic solvent dispersion can be made more uniform.
The fine particle dispersant is not particularly limited as long as the conductive fine particles can be dispersed in an organic solvent. For example, amine compounds such as octylamine, hexylamine and oleylamine; sulfur compounds such as dodecanethiol Carboxylic acid compounds such as oleic acid; amphiphilic compounds for water and organic solvents described later; binders described later; Among these, an amphiphilic compound and a binder are preferable because the effects described below can be expected.
As said fine particle dispersing agent, these may be used independently and 2 or more types may be used.

The content of the fine particle dispersant is preferably 0.001 to 5% by mass with respect to 100% by mass of the organic solvent dispersion. If the amount is less than the above range, the aggregation of the fine particles in the organic solvent dispersion may not be sufficiently prevented. On the other hand, if the amount is larger, the conductivity of the formed conductive film may not be expressed. . More preferably, it is 0.01-3 mass% as content of a fine particle dispersing agent.

The organic solvent dispersion preferably contains an amphiphilic compound for water and the organic solvent. By containing an amphiphilic compound, when using the self-assembly method described later, it becomes easy to maintain the shape of water droplets taken into the coating film in a suitable form by its surface active function, for example, In addition, aggregation of water droplets can be controlled, and it becomes easy to form a mesh of a conductive film. The amphiphilic compound may be an amphiphilic low molecular compound or an amphiphilic polymer compound, and is not particularly limited. As a form that can further exhibit the surface active function, an amphiphilic polymer compound is preferable. In order to suitably maintain the form of water droplets taken into the coating film in the organic solvent dispersion, it is preferable to use a compound having a surface active function. That is, it is one of the preferable embodiments of the present invention that the organic solvent dispersion contains a compound having a surface active function.

The content of the amphiphilic compound is preferably 0.001 to 25% by mass with respect to 100% by mass of the organic solvent dispersion. By setting the content in such a range, when using a self-assembly method when forming a conductive film having a pattern, the form of water droplets taken into the coated organic solvent dispersion is more stable. And can be held. When the amount is less than 0.001% by mass, it is difficult to grow and transport water droplets on the surface of the coating film, and the aperture ratio may be lowered. If it exceeds 25% by mass, water droplets aggregate on the surface of the coating film, and there is a possibility that pores are not sufficiently formed. Moreover, there exists a possibility that electroconductivity may become difficult to express. More preferably, it is 0.001-15 mass% as content of an amphiphilic compound, More preferably, it is 0.001-5 mass%, Most preferably, it is 0.003-1 mass%.

The amphiphilic compound is preferably a compound having both a hydrophilic group and a hydrophobic group. The amphiphilic compound is expected to have an effect of preventing water droplets attached to the organic solvent dispersion coated on the substrate from fusing together in the self-assembly method described later. The amphiphilic compound is not particularly limited as long as it is a compound having an affinity for both water and an organic solvent. Examples of the hydrophobic group include hydrocarbons having 5 to 20 carbon atoms. And nonpolar groups such as a group, a phenyl group, and a phenylene group. Examples of the hydrophilic group include a hydroxyl group, a carboxyl group, an amino group, a carbonyl group, a sulfo group, an ester group, an amide group, an ether group, and a pyridine group.

Examples of the amphiphilic compound include anionic surfactants such as sodium alkyl sulfate, cationic surfactants such as alkyl ammonium chloride, polyoxyethylene alkyl ether, sorbitan fatty acid ester, sucrose fatty acid ester, glycerin fatty acid ester, poly Nonionic surfactants such as glycerin fatty acid esters, alkylamines such as octylamine and dodecylamine, amphiphilic polymers and the like can be mentioned. From the viewpoint of solubility in organic solvents and water, nonionic surfactants and amphiphilic polymers are preferred. These amphiphilic compounds may be used alone or in combination of two or more.

Nonionic surfactants include polyhydric alcohol fatty acid esters; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene nonylphenyl ether, polyoxyethylene And polyoxyethylene alkyl phenyl ethers such as octyl phenyl ether; alkyl glucosides; polyoxyethylene fatty acid esters; fatty acid alkanolamides. Among these, polyhydric alcohol fatty acid esters are preferable because a pattern can be uniformly formed with a small addition amount.

The polyhydric alcohol fatty acid ester is produced by combining a polyhydric alcohol and a fatty acid by an ester bond by a commonly used general method. For example, sorbitan fatty acid ester, sucrose fatty acid ester, Examples include glycerin fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene glycerin fatty acid ester, and propylene glycol fatty acid ester. Among these, glycerol fatty acid ester, polyglycerol fatty acid ester, and sorbitan fatty acid ester are preferable, and polyglycerol fatty acid ester is particularly preferable.
In the polyhydric alcohol fatty acid ester, the fatty acid that forms an ester bond to one molecule of the polyhydric alcohol may be one kind or two or more kinds.

Specific examples of the polyhydric alcohol fatty acid ester include propylene glycol dicaprate, DK ester F-10 (manufactured by Daiichi Kogyo Seiyaku), DK ester F-20W (manufactured by Daiichi Kogyo Seiyaku), and DK ester F. -50 (Dai-Industry Pharmaceutical Co., Ltd.), DK Ester F-70 (Dai-Industry Pharmaceutical Co., Ltd.), DK Ester F-90 (Daiichi Kogyo Seiyaku Co., Ltd.), sorbitan trioleate, sorbitan sesquioleate, sorbitan monooleate Sorbitan monostearate, sorbitan monococoate, glyceryl stearate, glyceryl isostearate, glyceryl oleate, glyceryl distearate, polyglyceryl-2 stearate, polyglyceryl-2 oleate, polyglyceryl-2 isostearate, polyglyceryl triisostearate 2, Polyglyceryl-3 isostearate, polyglyceryl-4 stearate, polyglyceryl-4 oleate, polyglyceryl pentastearate-4, polyglyceryl oleate-6, polyglyceryl-6-stearate, polyglyceryl-10 distearate, polyglyceryl-10 diisostearate Polyglyceryl tristearate-10, polyglyceryl-10 pentastearate, polyglyceryl pentaisostearate, polyglyceryl-10 pentaoleate, polyglyceryl-10 heptearate, polyglyceryl-10 heptaoleate, polyglyceryl-10 decastearate, deca Polyglyceryl-10 isostearate, polyglyceryl-10 decaoleate, PEG-3 glyceyl isostearate Le, oleate polyoxyethylene (4) glyceryl and the like are suitably used. More preferably, polyglyceryl-3 isostearate, polyglyceryl-2 isostearate, polyglyceryl-10 pentaisostearate, polyglyceryl-10 pentaoleate, polyglyceryl-10 heptaoleate, glyceryl oleate, polyglyceryl oleate-2, sorbitan monooleate PEG-3 glyceryl isostearate is used.

As the amphiphilic polymer, a polymer having polyacrylamide as a main chain skeleton, a hydrophilic group and a hydrophobic group in the side chain, and co-polymerization of hydrophobic (meth) acrylate and hydrophilic (meth) acrylate Polymer, copolymer of styrene and hydrophilic (meth) acrylate, copolymer of styrene and 2-vinylpyridine, octadecyl isocyanate modified polyethyleneimine (Epomin RP-20, manufactured by Nippon Shokubai Co., Ltd.) A polymer having a hydrophilic group and having a hydrophobic group in the side chain, a block copolymer of polyethylene glycol and polypropylene glycol having a hydrophobic group and a hydrophilic group, or sodium of dichlorodiphenylsulfone and bisphenol A It is obtained by polycondensation with a salt, and a diphenylenedimethylmethylene group which is a hydrophobic group and a divalent group which is a hydrophilic group in the main chain skeleton. Polysulfone or the like having a Enirensuruhon group.

The amphiphilic polymer preferably has a weight average molecular weight of 5,000 to 500,000. When the conductive film having a network pattern is formed using the self-assembly method described later, the pattern structure is less likely to collapse during solvent evaporation when the weight average molecular weight is from 5,000 to 500,000. Become. More preferably, the weight average molecular weight is 10,000 or more and 300,000 or less, still more preferably 50,000 or more and 200,000 or less, and particularly preferably 90,000 or more and 100,000 or less.
The number average molecular weight of the amphiphilic polymer is preferably 3000 or more and 500,000 or less. If the number average molecular weight is from 3,000 to 500,000, the pattern structure collapses when the solvent is evaporated when a conductive film having a network pattern is formed using the self-assembly method described later. It becomes difficult. The number average molecular weight of the amphiphilic polymer is more preferably 5000 or more and 300,000 or less, further preferably 10,000 or more and 200,000 or less, and 20,000 or more and 100,000 or less. It is particularly preferred.
The weight average molecular weight (Mw) and the number average molecular weight (Mn) are, for example, gel permeation chromatography (GPC) HLC-8120 (manufactured by Tosoh Corporation) as a measuring device, and TSK-GEL GMHXL-L (Tosoh Corporation) as a column. Can be measured as a molecular weight in terms of polystyrene.

Examples of the polymer having polyacrylamide as a main chain skeleton and a hydrophilic group and a hydrophobic group in a side chain include, for example, the following formula:

(Wherein n and m are the same or different and represent the number of repeating structural units) (dodecylacrylamide) _n- (ω-carboxyhexylacrylamide) _m -random copolymer (hereinafter, “ Also referred to as “CAP”).
In the formula, the ratio of n to m (n / m) is preferably 1 to 15, more preferably 2 to 12, and still more preferably 3 to 10.

Examples of the hydrophobic (meth) acrylate include normal hexyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, heptyl (meth) acrylate, benzyl (meth) acrylate, octyl (meth) acrylate, and 2-ethylhexyl. (Meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like.

Examples of the hydrophilic (meth) acrylate include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate. , Diethylaminoethyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl 2-hydroxypropyl phthalate, glycidyl (meth) acrylate, 2- (meth) acryloyloxyethyl Acid phosphate, caprolactone-modified (meth) acrylate and the like.

Further, a hydrophobic radical polymerizable monomer such as hydrophobic (meth) acrylamide or styrene is used instead of the hydrophobic (meth) acrylate, and hydrophilic (meth) acrylamide, N is used instead of the hydrophilic (meth) acrylate. -Hydrophilic radically polymerizable monomers such as vinylpyrrolidone may be used.
Each of the hydrophobic (meth) acrylate and the hydrophilic (meth) acrylate may be used alone or in combination of two or more. Moreover, a different component may be included.

The organic solvent dispersion preferably contains a binder. Adhesiveness with a board | substrate improves that it contains a binder. The binder is not particularly limited as long as it is a polymer that dissolves in an organic solvent, and examples thereof include urethane resins, acrylic resins, polyester resins, polyacrylamides, polyalkylene glycol polymers, and polystyrene.
These binders may be used independently and may use 2 or more types together.

The binder preferably has a weight average molecular weight of 5000 or more and 500,000 or less. When the weight average molecular weight of the binder is within such a range, the adhesion between the coated organic solvent dispersion and the substrate can be made sufficient. More preferably, the weight average molecular weight is 10,000 or more and 300,000 or less, still more preferably 50,000 or more and 200,000 or less, and particularly preferably 90,000 or more and 100,000 or less.
In addition, the weight average molecular weight of a binder can be measured similarly to the weight average molecular weight of the amphiphilic polymer mentioned above, for example.

The content of the binder is preferably 0.001 to 50% by mass with respect to 100% by mass of the organic solvent dispersion. By setting it as content of such a range, the adhesiveness of the coated organic solvent dispersion and a board | substrate can be made sufficient. In addition, as described above, when an amphiphilic polymer is used as the binder, the organic solvent dispersion applied when the self-organization method is used by setting the content in such a range. The form of water droplets taken in can be more stably maintained. When the amount is less than 0.001% by mass, when the self-assembly method described later is used, it is difficult to grow and transport water droplets on the surface of the coating film, and the aperture ratio may be lowered. If it exceeds 50% by mass, the coatability may be deteriorated, and the aperture ratio may be lowered without sufficient growth of water droplets.
More preferably, it is 0.001-25 mass% as content of a binder, More preferably, it is 0.005-25 mass%.

As described above, when the organic solvent dispersion contains an infrared absorber and an amphiphilic compound in addition to the conductive fine particles, the conductive fine particles, the infrared absorber, and the amphiphilic compound are 60: It is preferable to contain by volume ratio of 10: 30-90: 5: 5. By including in the organic solvent dispersion within such a range, the conductivity of the formed conductive film can be made more sufficient while maintaining good pattern formation. More preferably, the volume ratio of the conductive fine particles, the infrared absorber, and the amphiphilic compound is 70:10:20 to 90: 5: 5, and more preferably 75:10:15 to 85: 5. : 10.

The organic solvent dispersion preferably has a moisture content before coating of 10% by mass or less. When a large amount of water is contained in the organic solvent dispersion before coating, the water in the organic solvent dispersion becomes large water droplets due to surface tension, and a conductive film having a network pattern using a self-assembly method described later When forming, there is a possibility that the mesh cannot be made fine. More preferably, the water content before coating is 5% by mass or less.

The organic solvent dispersion is applied to a substrate. The said board | substrate is not specifically limited, What is necessary is just to be able to apply the organic solvent dispersion on the surface. As the substrate, for example, various substrates such as a glass substrate, a plastic substrate, a single crystal substrate, a semiconductor substrate, and a metal substrate can be used. When used for a display such as electronic paper (digital paper), a transparent substrate such as a glass substrate or a transparent plastic substrate is preferably used as the substrate. The transparent substrate is a substrate having a high visible light transmittance. For example, the visible light transmittance of a wavelength of 400 to 700 nm is preferably 50% or more. More preferably, the transmittance is 70% or more, and more preferably 80% or more. Use of a glass substrate or a plastic substrate is also preferable from the viewpoint of cost reduction. In addition, when used as a display device such as electronic paper, it is also a preferable form to use a flexible substrate. Examples of the plastic substrate include ester films such as polyethylene terephthalate and polyethylene naphthalate; acrylic films; cycloolefin films; olefin films; resin films such as polyamide, polyphenylene sulfide, and polycarbonate.

The substrate on which the organic solvent dispersion is applied is preferably a substrate having a hydrophilic surface. Since the surface of the substrate is hydrophilic, water droplets can be easily brought into contact with the substrate, the penetration rate of the pores can be increased, and formation of an extra polymer / particle film on the bottom surface of the pores can be prevented. In the case of forming a conductive film having a mesh pattern by using a self-organization method to be described later, the shape of the pores can be a conductive film having a high aperture ratio. The substrate having a hydrophilic surface preferably has a water contact angle of 90 ° or less. By being 90 ° or less, the shape of the water droplets taken into the organic solvent dispersion can be adjusted, and the shape of the pores can be made to have a high aperture ratio. More preferably, it is 60 degrees or less as an upper limit of the contact angle with respect to water, More preferably, it is 30 degrees or less.

It is preferable that the substrate on which the organic solvent dispersion is applied has been subjected to a hydrophilic treatment on the substrate surface. According to this, water droplets taken into the organic solvent dispersion can be held in a suitable shape. Further, the shape of the conductive film can be further controlled by controlling the hydrophilicity of the substrate surface. The hydrophilic treatment method is not particularly limited, but for example, a method of immersing in an alkaline solution is preferable. Although it does not specifically limit as an alkaline solution, A potassium hydroxide solution, a sodium hydroxide solution, etc. can be used preferably. Specifically, a saturated potassium hydroxide ethanol solution or the like can be preferably used. Examples of the hydrophilic treatment method include corona discharge treatment, plasma treatment, and UV-ozone treatment. It is preferable to select a preferable method as appropriate depending on the type of the substrate, the type of the organic solvent dispersion, and the like. Moreover, the value of the preferable contact angle mentioned above can be used for the contact angle of the board | substrate by hydrophilization.

A self-organization method including a step of evaporating an organic solvent while condensing a coated organic solvent dispersion on the surface of the coating film, which is one of preferred embodiments of the present invention, will be described.
According to the self-organization method, water droplets generated by condensation can be taken into the coating film while the organic solvent is evaporated. Then, the organic solvent evaporates and the taken water droplets are dried, so that a hole corresponding to the taken water droplets can be formed. Thereby, the mesh-like line part formed from electroconductive fine particles and the void | hole part are formed. Thus, by producing a conductive film having a mesh pattern by the self-organization method, a mesh-like conductive film having further excellent conductivity and light transmittance can be produced easily and at low cost. It becomes possible. That is, the conductive film formed by the method for producing a conductive film of the present invention is preferably a mesh-like conductive film formed by a mesh-like line portion and a hole portion.

The self-assembly method includes a step of evaporating the organic solvent while the coated organic solvent dispersion is condensed on the surface of the coating film. Condensation on the coating film surface can be performed by adjusting the humidity near the coating film surface or the temperature difference between the atmosphere near the coating film surface and the coating film surface. That is, the conditions for condensation on the coating film surface may be used. In the present invention, when a conductive film having a mesh pattern is formed by a self-organization method, a mesh-like conductive portion and a void portion are formed on the coating film surface. It is technically apparent that this is caused by evaporating the organic solvent while causing condensation on the coating film surface by the mechanism shown in FIG. 1-1.
From the above, it can also be said that the self-organization method includes a step of evaporating the coated organic solvent under conditions that cause condensation on the surface of the coating film. The conditions under which condensation occurs on the surface of the coating film are, for example, conditions in which the dew point of the atmosphere for evaporating the organic solvent is higher than the temperature of the coating film surface. The method for causing dew condensation is not particularly limited. For example, the method for cooling the surface of the coating film to a dew point below the atmosphere for evaporating the organic solvent, or the atmosphere for evaporating the organic solvent as a humidified atmosphere. A method of making the dew point of the atmosphere higher than the temperature of the coating film surface is suitable. These methods may be used in one method or a combination of a plurality of methods. By combining a plurality of methods, the conditions for evaporating the organic solvent can be controlled more precisely, and the form of the mesh pattern of the conductive film can be adjusted.

The method for cooling the temperature of the coating film surface below the dew point of the atmosphere for evaporating the organic solvent is not particularly limited, but a method for forcibly cooling the coating film using a cooling element or the like, an organic solvent And a method of lowering the surface temperature of the coating film by latent heat of evaporation. Moreover, as a method of forcibly cooling the coating film using a cooling element or the like, it is also preferable to cool the temperature of the coating film surface by cooling the substrate coated with the organic solvent dispersion. By cooling by such a method, the difference between the temperature of the coating film surface and the temperature of the atmosphere in which the organic solvent is evaporated increases, so that condensation can be more easily generated. That is, it is preferable to make the temperature of the coating film surface lower than the temperature of the atmosphere in which the organic solvent is evaporated. For example, a method of cooling the substrate coated with the organic solvent dispersion by using a cooling device such as a Peltier device is one of preferable methods. With this method, temperature control of the coating film surface and control of the atmosphere around the coating film for evaporating the organic solvent can be performed independently, so that more precise condition setting can be performed. By adjusting the conditions more, the shape, transmittance, conductivity, etc. of the manufactured conductive film can be controlled, so it is possible to form a conductive film in a suitable form according to various applications. It becomes.

In order to cause condensation on the coating film surface when the organic solvent is evaporated, a humidified atmosphere is preferable. That is, the step of evaporating the organic solvent is preferably a step of evaporating the organic solvent in a humidified atmosphere. By setting the humidified atmosphere, dew condensation is likely to occur on the surface of the organic solvent dispersion. As a method of setting the atmosphere at the time of evaporating the organic solvent as a humidified atmosphere and making the dew point higher than the temperature of the coating film surface, a method of humidifying the entire surroundings where the organic solvent is evaporated, a humidified gas is blown on the coating film surface. The attaching method is suitable. By using a humidified atmosphere, condensation tends to occur on the surface of the coating film. When the humidified gas is sprayed onto the surface of the coating film, the shape and amount of water droplets taken into the coating film changes depending on the spraying speed, etc., so the organic solvent is evaporated by adjusting the spraying speed. The conditions to be adjusted can be adjusted. Thereby, the shape of the conductive film can be controlled, and its characteristics (light transmittance, conductivity, etc.) can be improved. The humidified atmosphere may be any atmosphere as long as the humidity is sufficient to cause condensation on the surface of the coating film of the organic solvent dispersion, that is, the same conditions as the humidification, The step of evaporating the organic solvent may be performed under a high humidity environment.

The humidified atmosphere preferably has a relative humidity of 50% or more. When the relative humidity is as high as 50% or more, condensation tends to occur on the surface of the coating film, and the conductive film can be efficiently produced. The relative humidity is more preferably 55% or more, and still more preferably 60% or more.

The upper limit of the wind speed for blowing the humidified gas is preferably 5 m / s (300 m / min) or less as the flow velocity. When the humidified gas is blown at a flow rate exceeding 5 m / s, the shape of the coated organic solvent dispersion is changed by blowing the humidified gas, and the film shape after drying the organic solvent is changed to the desired shape. May not be able to be retained. The flow rate that is more preferable as the upper limit of the wind speed for blowing the humidified gas is 3 m / s (180 m / min) or less, and more preferably 1 m / s (60 m / min) or less. Moreover, as a minimum of the said wind speed, it is preferable that it is 0.02 m / min or more. When the wind speed is 0.02 m / min or less, water droplets may not be sufficiently taken into the coated organic solvent dispersion. The flow rate more preferable as the lower limit of the wind speed is 0.1 m / min, more preferably 0.2 m / min or more, and particularly preferably 0.4 m / min or more. The upper limit of the time for blowing the humidified gas is preferably within one hour from the viewpoint of productivity. More preferably, it is within 40 minutes, and more preferably within 30 minutes. The lower limit of the time for blowing the humidified gas is preferably 1 minute or longer. If it is less than 1 minute, the organic solvent may not be sufficiently evaporated, and water droplets may not be sufficiently taken into the organic solvent dispersion. More preferably, it is 5 minutes or more, More preferably, it is 10 minutes or more. For example, a suitable time is about 20 minutes (15 to 25 minutes). The relative humidity of the humidified gas to be blown is also preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more, as described above.

Here, a method of manufacturing a conductive film having a mesh pattern by the self-organization method will be described with reference to FIGS. FIG. 1-2 is a flowchart showing a process of evaporating the organic solvent while the coated organic solvent dispersion is condensed on the coating film surface. As shown in FIG. 1-2 (a), the organic solvent dispersion (hereinafter also referred to as “coating film”) applied to the substrate 11 is a method for cooling the substrate 11 on which the coating film 12 is formed, or humidification. By setting it as the conditions which cause dew condensation on the coating film surface by the method of blowing gas, dew condensation occurs on the surface of the coating film as shown in FIG. The water droplet 13 generated by the condensation is taken into the coating film 12 as shown in FIGS. 1-2 (c) and 1-2 (d). In addition, the coated organic solvent dispersion evaporates with time and becomes thinner. Then, the organic solvent and the water droplets taken in by the humidified atmosphere evaporate, and as shown in FIG. It will be formed. In this way, a mesh pattern is formed. FIG. 2 is a schematic plan view showing the form of the film after the organic solvent evaporates, in which a mesh-like line portion 15 including a metal is formed around the formed hole portion 14. Thus, a conductive film having a mesh pattern is formed.
Also, as shown in FIG. 3, a method of evaporating an organic solvent by cooling a substrate 21 and a coating film 22 using a Peltier element 20 and spraying a humidified gas on a coated organic solvent dispersion. Is one of the preferred embodiments of the method for producing a conductive film of the present invention. That is, the manufacturing method is preferably a manufacturing method including a step of cooling the substrate and the coating film, blowing a humidified gas onto the coating film, and evaporating the organic solvent while causing condensation on the coating film surface.

The conductive film manufacturing method includes electroless plating after the step of evaporating the organic solvent while condensing the coated organic solvent dispersion on the coating surface and before the step of irradiating infrared rays. It is preferable to include the process to perform. Thus, by performing electroless plating, the conductivity of the obtained conductive film can be further improved.

The present invention is also a conductive film manufactured by the above manufacturing method. By being manufactured by the above manufacturing method, the conductive film can be a transparent conductive film excellent in conductivity and light transmittance. Furthermore, when the conductive film having a network pattern is formed by a self-organization method including a step of evaporating the organic solvent while the organic solvent dispersion applied to the substrate is condensed on the surface of the coating film, The conductive film is a network-like conductive film formed by a mesh-like line portion and a hole portion of a conductive substance, and a transparent conductive film having more excellent light transmittance and conductivity is used. it can.
Note that the arrangement form of the mesh-like line portions and the hole portions in the conductive film having a mesh-like pattern may be random or regularly arranged. In addition, there may be some meshes where large and small meshes are mixed, but some meshes may be cut off, but overall, it is evaluated that a mesh-like structure is recognized in a micro technical field. It is desirable that That is, it is only necessary to confirm a network structure by observing with a microscope. The network structure is preferably formed on the entire surface of the conductive film, but may be appropriately set according to the use for which the conductive film is used, and may be partially as long as the function as the conductive film can be exhibited. It may be. Other preferred mesh-like forms will be described later. Here, the term “random” means that the mesh-like line portions and the hole portions are not arranged based on a certain rule.
Hereinafter, among the conductive films of the present invention, the form of a conductive film having a mesh pattern that has particularly excellent conductivity and light transmittance will be described. In addition, as a more preferable form of the electroconductive film manufactured by the said manufacturing method, it is the same as that of the preferable form of the mesh-shaped electroconductive film demonstrated below.

As the form of the mesh-like conductive film, the average area of the pores is preferably 400 μm ² or less, and the line width of the mesh-like line part is preferably 5 μm or less. Since the average area of the pores is small and the line width of the mesh-like line part is narrow, a highly conductive and mesh-like conductive film can be formed. The average area of the pores is more preferably 300 μm ² or less, still more preferably 200 μm ² or less, and particularly preferably 100 μm ² or less. In addition, the hole portion preferably has an average maximum ferret diameter of 20 μm or less, and more preferably 10 μm or less. The aperture ratio due to the pores is preferably 60% or more, whereby a conductive film with improved light transmittance can be obtained. The aperture ratio due to the voids is more preferably 65% or more, further preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. The line width of the mesh-like line portion is more preferably 2 μm or less, and further preferably 1 μm or less. The maximum ferret diameter is the maximum between two parallel lines drawn so as to be in contact with the outline of each hole, and is called the maximum ferret diameter. The average maximum ferret diameter is measured for each hole. The average of the maximum ferret diameter is called the average maximum ferret diameter.

The present invention further relates to a network-like conductive film formed by a mesh-like line portion and a hole portion of a conductive substance, and the conductive film has an average area of the hole portion of 400 μm ² or less. Also, the conductive film having a line width of the mesh-like line portion of 5 μm or less. Since the average area of the pores is small and the line width of the mesh-like line part is narrow, a mesh-like transparent conductive film having high light transmittance and high uniformity can be formed. For example, when used for electronic paper or the like, a voltage can be uniformly applied to microcapsules for display. When the mesh is wide (the area of the pores is large), when the voltage is applied by a conductive film to change the color of the microcapsules, the pores must be fine if the mesh is not fine. The entire microcapsule is contained in the part, and no voltage is applied to such a capsule. Further, the finer mesh makes the conductivity more uniform. According to this, for example, when used for a touch panel, the accuracy of position recognition increases. Such a network-like conductive film can be formed using the above-described method for manufacturing a conductive film. The arrangement form of the mesh-like line portions and the hole portions in the conductive film may be random or regularly arranged. For example, when forming a mesh-like conductive film, in order to make the mesh finer, it is easier to manufacture if it is random. One.

In the conductive film, the average area of the pores is 400 μm ² or less, and the line width of the mesh-like line part is 5 μm or less, which means that the mesh of the conductive film is fine. By having a fine mesh, it is possible to have a uniform conductivity within the surface of the conductive film. When the average area of the pores exceeds 400 μm ² , the in-plane uniformity of the conductive film is not sufficient, and for example, there is a possibility that variations in light transmission and conductivity occur. In addition, as described above, when used for a display such as electronic paper, there is a possibility that the function as a conductive film may be insufficient due to the occurrence of a portion where no voltage is applied. The average area of the pores is more preferably 300 μm ² or less, still more preferably 200 μm ² or less, and particularly preferably 100 μm ² or less. In addition, the hole portion preferably has an average maximum ferret diameter of 20 μm or less, and more preferably 10 μm or less. The line width of the mesh-like line portion is 5 μm or less, and the thin line width can suppress moire that may occur, for example, in a display or the like. When the line width of the mesh-like line portion exceeds 5 μm, the aperture ratio becomes small and the light transmittance may not be sufficient. The line width of the mesh-like line portion is more preferably 2 μm or less, and further preferably 1 μm or less. As described above, by controlling the average area of the hole portions and the line width of the mesh-like line portions, the conductivity and light transmittance of the conductive film can be controlled to more preferable values.

The conductive film preferably has an aperture ratio of 60% or more due to the pores. Since the light transmittance can be improved by increasing the aperture ratio, it can be suitably used for a display such as electronic paper. If it is less than 60%, sufficient light transmittance cannot be obtained, and there is a possibility that sufficient characteristics as a conductive film having transparency cannot be exhibited. The opening ratio due to the pores is more preferably 65% or more, further preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more.
The aperture ratio, line width, average area of pores, and average maximum ferret diameter can be determined by the following methods.

<How to find the aperture ratio, line width, average area of pores, average maximum ferret diameter>
The surface of the conductive film was observed with an ultrahigh resolution field emission scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) at a magnification of 1000 times, and the observed image was image processing software (Image-Pro Plus ver. 4). 0.0, manufactured by Media Cybernetics, USA), the following methods are used to determine the aperture ratio, line width, average area of pores, and ferret diameter of the conductive film.

The image observed with a microscope (this is called the “original image”) is binarized into black and white using the above-mentioned image processing software so that the conductive part is black and the other part (mesh opening) is white. To do. At this time, as the binarization threshold value, the peak values of white and black are obtained from the tone histogram, and set to the intermediate value. Next, black and white inversion processing of the binarized image is performed (this image is referred to as “binarized image”). At this time, the area ratio of the black portion with respect to the entire area is obtained and set as the aperture ratio.

Moreover, the area of the white part of a binarized image is calculated | required and let this be the area (S) of an electroconductive part. Next, thinning processing of the binarized image is performed (this image is referred to as “thinning processing image”). The area of the white part of the thinned image is obtained, and this is defined as the length (L) of the conductive part. Using the values of S and L obtained above, the line width of the conductive portion is obtained by the following formula (1).
Line width of conductive part = S / L (1)

Subsequently, the black portion of the binarized image is extracted (this image is referred to as “extracted image”). During extraction, voids on the boundary are excluded. In addition, pores having an area of 1 μm ² or less are also excluded. At this time, the area of each element and the maximum ferret diameter are measured and averaged to obtain the average area of the hole portion and the average maximum ferret diameter of the hole portion, respectively.

The thickness of the mesh line portion is preferably 200 nm or more. When the thickness is 200 nm or more, sufficient conductivity can be obtained even if the line width is reduced. When the film thickness of the conductive film is less than 200 nm, the conductivity is low, and the characteristics as the conductive film may not be sufficiently exhibited. More preferably, the thickness of the mesh line portion is 1 μm or more. In addition, the thickness of a mesh line part is calculated | required by measuring the maximum film thickness, for example, can be measured by using a laser microscope. As a measuring method, the coating film was observed at a magnification of 50 times using a laser microscope (VK-9700, manufactured by Keyence Corporation), and the maximum level difference of the coating film was measured at 10 locations from the observed image, and the average value was obtained. The maximum film thickness of the conductive film.

The conductive film of the present invention preferably has a light transmittance of 20% or more for visible light (wavelength: 400 to 700 nm). By increasing the light transmittance, for example, it can be suitably used for a display device such as electronic paper. The light transmittance is more preferably 40% or more, still more preferably 60% or more, and particularly preferably 80% or more. The light transmittance can be measured for light having a wavelength of 300 to 800 nm using, for example, a spectrophotometer (trade name “V-530”, manufactured by JASCO Corporation).

The conductive film of the present invention preferably has a total light transmittance of 20% or more. When the total light transmittance is 20% or more, for example, it can be suitably used for a display device such as electronic paper. More preferably, the total light transmittance is 40% or more, still more preferably 50% or more, and particularly preferably 60% or more. Most preferably, it is 75% or more.
In addition, the said total light transmittance can be measured based on JISK7361-1 using haze meter NDH5000 (made by Nippon Denshoku Industries Co., Ltd.), for example.

The conductive film of the present invention preferably has a surface resistivity of 10 ¹² Ω / □ or less. Since it has sufficient electroconductivity as it is such surface resistivity, it can be used suitably, for example with respect to display apparatuses, such as electronic paper. More preferably, it is 10 ⁸ Ω / □ or less, more preferably 10 ⁷ Ω / □ or less, and particularly preferably 10 ⁶ Ω / □ or less. Most preferably, it is 10 ⁵ Ω / □ or less.
In addition, in the conductive film having the above-described mesh pattern, particularly when the aperture ratio due to the holes is high, the area of the mesh line portion is small and compared with the conductive film having the same film thickness with a low aperture ratio. As a result, the resistivity of the conductive film increases. Therefore, the area of the mesh line portion is preferably an area that can ensure sufficient conductivity. The preferred area of the mesh line portion varies depending on the film thickness and area of the conductive film, the metal material constituting the conductive film, and the like. For example, the surface resistivity in the plane of the conductive film is 10 ¹² Ω / □ or less. It is preferable to set the area of the mesh line portion so that According to this, the surface resistivity of the conductive film is more preferably 10 ⁸ Ω / □ or less, further preferably 10 ⁷ Ω / □ or less, and particularly preferably 10 ⁶ Ω / □ or less. is there. Most preferably, it is 10 ⁵ Ω / □ or less.
The surface resistivity is measured, for example, by a four-terminal four-probe method using a resistivity meter Lorester-GP (manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: ASP probe), or a digital insulation meter DSM-8104. (Manufactured by Hioki Electric Co., Ltd.) can be used in accordance with JIS K6911.

The use of the conductive film is not particularly limited, and can be used for any application that requires conductivity. For example, it can be used as an electromagnetic wave shielding film (EMI shield film) used for a plasma display or the like, and can also be used as an electrode used for a display device of electronic paper (digital paper) or a liquid crystal display device. It can also be used for touch panels and the like.
Thus, the present invention is also a conductive film used for digital paper.

By the method for producing a conductive film of the present invention, a conductive film having excellent conductivity and light transmittance can be produced simply and inexpensively. In addition, it does not require a high-temperature processing step such as baking in the manufacturing process, and since the conductive film can be formed in a short baking time, a general-purpose material that does not have high heat resistance such as a PET film as a substrate. A polymer substrate can be used, which is a highly productive method. And since the conductive film obtained in this way has the outstanding electroconductivity and light transmittance, it can be used suitably for displays, such as electronic paper.

FIG. 1-1 is a conceptual diagram of a cross-section of a coating film over time, showing an example of a process of evaporating an organic solvent while allowing the applied organic solvent dispersion to condense on the coating film surface. FIGS. 1-2 (a) to (e) are conceptual diagrams showing a process of evaporating the organic solvent while the applied organic solvent dispersion is condensed on the surface of the coating film. FIG. 2 is a schematic plan view of a mesh-like conductive film in which pores and mesh-like line portions are formed. FIG. 3 is a schematic cross-sectional view showing a method of using a Peltier device to cool a substrate and a coating film and to evaporate while blowing a humidified gas onto the coating film.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

In the following examples and comparative examples, the physical properties of the conductive film were measured as follows.
<Maximum film thickness>
Using a laser microscope (VK-9700, manufactured by Keyence Corporation), the coating film was observed at a magnification of 50 times. From the observed image, the maximum level difference of the coating film was measured at 10 locations, and the average value was the maximum of the conductive film. The film thickness was taken.

For the aperture ratio, line width, average area of pores, and average maximum ferret diameter, the surface of the conductive film was magnified 1000 with an ultra-high resolution field emission scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation). The observed image was obtained by processing with the following method using image processing software (Image-Pro Plus ver. 4.0, manufactured by Media Cybernetics, USA).
<Opening ratio>
The image observed with a microscope (this is called the “original image”) is binarized into black and white using the above-mentioned image processing software so that the conductive part is black and the other part (mesh opening) is white. did. At this time, as the binarization threshold value, the peak values of white and black are obtained from the tone histogram, and set to the intermediate value. Next, the black and white reversal processing of the binarized image was performed (this image is referred to as “binarized image”). At this time, the area ratio of the black portion with respect to the entire area was determined and used as the aperture ratio.
<Line width>
The area of the white part of the binarized image was determined and this was defined as the area (S) of the conductive part. Next, thinning processing of the binarized image was performed (this image is referred to as “thinning processed image”). The area of the white part of the thinned image was obtained, and this was defined as the length (L) of the conductive part. Using the values of S and L obtained above, the line width of the conductive portion was obtained by the following formula (1).
Line width of conductive part = S / L (1)
<Average area of holes, average maximum ferret diameter of holes>
The black part of the binarized image was extracted (this image is referred to as “extracted image”). During extraction, voids on the boundary were excluded. In addition, pores having an area of 1 μm 2 or less were also excluded. At this time, the area of each element and the maximum ferret diameter of each hole portion were measured and averaged to obtain the average area of the hole portion and the average maximum ferret diameter of the hole portion, respectively.

<Surface resistivity>
When the surface resistivity is less than 10 ⁷ Ω / □, the surface resistivity of the conductive film is four-terminal four using a resistivity meter Lorester-GP (Mitsubishi Chemical Analytech, probe: ASP probe). When measured by a probe method and the surface resistivity was 10 ⁷ Ω / □ or more, it was measured according to JIS K6911 using a digital insulation meter DSM-8104 (manufactured by Hioki Electric Co., Ltd.).
<Total light transmittance>
The total light transmittance of the conductive film was measured according to JIS K7361-1 using a haze meter NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

<Adhesion>
The surface of the conductive film was rubbed with Kimwipe and evaluated according to the following criteria based on how the coating film was peeled off.
Evaluation criteria ○: not peeled Δ: peeled ×: easily peeled <Shrinkage degree of film>
The degree of shrinkage of the conductive film after firing or infrared irradiation was evaluated visually according to the following criteria.
Evaluation standard 〇: not contracted △: contracted ×: markedly contracted

<Preparation of conductive fine particle dispersion>
A 1 L beaker containing 148.1 g of octylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was placed in a constant temperature bath at 40 ° C. Next, 18.6 g of silver acetate (manufactured by Wako Pure Chemical Industries, Ltd.) was added and sufficiently stirred and mixed for 20 minutes to prepare a uniform mixed solution. Subsequently, a reduction treatment was performed by gradually adding 20 g of a 20 wt% sodium borohydride aqueous solution.
After the reduction treatment, 200 g of acetone was added, and after standing for a while, a precipitate composed of silver and organic matter was separated and collected by filtration. Cyclohexane was added to the recovered material, redissolved, cooled to 10 ° C. or lower, and then filtered again to prepare a cyclohexane dispersion solution with reduced impurities. Next, cyclohexane was distilled off with an evaporator to prepare a conductive fine particle dispersion containing 20 wt% of silver fine particles. This solution was a solution containing 9 wt% octylamine and 71 wt% cyclohexane in addition to the silver fine particles. When this solution was observed with an FE-SEM (field emission scanning electron microscope), it was confirmed to be a nanoparticle dispersion having a particle size distribution with an average particle size of 4 nm and a variation coefficient of 14%.

<Synthesis of near-infrared absorbing dye>
In a 100 ml four-necked flask, 12.73 g (26.2 mmol) of 3,6-difluoro-4,5-bis (2,5-dichlorophenoxy) phthalonitrile, 0.6 g (4 mmol) of divanadium trioxide , 0.76 g (4 mmol) of p-toluenesulfonic acid and 50 ml of benzonitrile were charged and stirred at reflux temperature for about 5 hours. After cooling, the reaction solution was poured into 500 ml of toluene, and the resulting solid was filtered. Further, it was washed with 200 ml of toluene to obtain VOPc (2,5-Cl ₂ PhO) ₈ F ₈ .
A 50 ml 4-necked flask was charged with 2 g (0.99 mmol) of the obtained VOPc (2,5-Cl ₂ PhO) ₈ F _{8 and} 12 ml of benzylamine, and stirred at 65 ° C. for about 12 hours. Thereafter, the inorganic content was filtered, and the filtrate was concentrated to 8 ml and crystallized dropwise in 80 ml of isopropanol (IPA). The solid content was filtered with suction, and washed with stirring in 50 ml of IPA for 1 hour. The solid content was subjected to suction filtration and vacuum-dried at 60 ° C. overnight to obtain a near-infrared absorbing dye (VOPc (2,5-Cl ₂ PhO) ₈ (PhCH ₂ NH) ₈ ). In addition, as a near-infrared absorption pigment | dye, what was diluted to 2 wt% with toluene was used.

(Formulation example 1)
Using a conductive fine particle dispersion solution, the weight concentration of silver was 0.936 mg / ml (corresponding to 0.120% by mass with respect to 100% by mass of the cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10, Nikko Chemicals Co., Ltd.) prepared a cyclohexane solution (a) having a weight concentration of 0.0279 mg / ml (corresponding to 0.0036% by mass with respect to 100% by mass of the cyclohexane solution). Table 1 summarizes the formulation.

(Formulation example 2)
Using a conductive fine particle dispersion solution, the weight concentration of silver was 0.936 mg / ml (corresponding to 0.120% by mass with respect to 100% by mass of the cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10, manufactured by Nikko Chemicals Co., Ltd.) as a weight concentration of 0.0210 mg / ml (corresponding to 0.0027% by mass with respect to 100% by mass of cyclohexane solution), and near infrared absorbing dye as a weight concentration of 0.00699 mg / ml. A cyclohexane solution (b) of ml (corresponding to 0.000894 mass% with respect to 100 mass% of cyclohexane solution) was prepared. Table 1 summarizes the formulation.

(Formulation example 3)
Using the conductive fine particle dispersion solution, the weight concentration of silver was 0.937 mg / ml (corresponding to 0.120% by mass with respect to 100% by mass of the cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10, manufactured by Nikko Chemicals Co., Ltd.) as a weight concentration of 0.0140 mg / ml (corresponding to 0.0018% by mass with respect to 100% by mass of cyclohexane solution), and a near infrared absorbing dye as a weight concentration of 0.0140 mg / ml. A cyclohexane solution (c) of ml (corresponding to 0.00179% by mass with respect to 100% by mass of the cyclohexane solution) was prepared. Table 1 summarizes the formulation.
In addition, the symbol used in Table 1 is as follows.
Dye: Near-infrared absorbing dye Surfactant: NIKKOL Decaglyn 7-OV
Mass concentration in solution: Mass concentration in cyclohexane solution (for example, cyclohexane solution (a) indicates that 0.120 parts of silver is contained with respect to 100 parts of cyclohexane solution.)
Volume ratio: volume ratio of silver, pigment and surfactant concentration in solution: concentration in cyclohexane solution (for example, cyclohexane solution (a) contains 0.936 mg of silver per 1 ml of cyclohexane solution. Represents this.)

Example 1
<Film forming conditions>
Under an atmosphere of 23 ° C. and a relative humidity of 70%, 1.6 ml of a cyclohexane solution (a) was applied on a 5 cm square PET film substrate (trade name “Lumirror U34”, double-sided easy-adhesion treated PET, manufactured by Toray Industries, Inc.) Humidified air (relative humidity 70%) was blown at a flow rate of 1.6 m / min for 10 minutes to evaporate the organic solvent and form a dry film.
<Drying conditions>
It was dried (air-dried) at room temperature and normal pressure.
<Infrared irradiation conditions>
The film after drying was irradiated with infrared rays by arranging five infrared heaters ZKC2000 (manufactured by Heraeus) having a peak wavelength of 1.22 μm at intervals of 4 cm. The distance between the coating film and the heater was 5 cm, the watt density was adjusted to 160 kW / m ^2, and irradiation was performed for 2 seconds.
As a result of obtaining the maximum film thickness, the aperture ratio, the line width, the average area of the pores, the average maximum ferret diameter of the pores, the surface resistivity, and the total light transmittance of the conductive film thus obtained. It was street. In addition, as a result of evaluating the adhesion of the obtained conductive film and the degree of shrinkage of the film, the results are shown in Table 2.

(Example 2)
A conductive film was obtained in the same manner as in Example 1 except that the cyclohexane solution (b) was used, and the physical properties of the conductive film were evaluated in the same manner as in Example 1. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Example 3)
A conductive film was obtained in the same manner as in Example 1 except that the cyclohexane solution (c) was used, and the physical properties of the conductive film were evaluated in the same manner as in Example 1. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Comparative Example 1)
<Film forming conditions>
Under an atmosphere of 23 ° C. and a relative humidity of 70%, 1.6 ml of a cyclohexane solution (a) was applied on a 5 cm square PET film substrate (trade name “Lumirror U34”, double-sided easy-adhesion treated PET, manufactured by Toray Industries, Inc.) Humidified air (relative humidity 70%) was blown at a flow rate of 1.6 m / min for 10 minutes to evaporate the organic solvent and form a dry film.
<Drying conditions>
It was dried (air-dried) at room temperature and normal pressure.
<Baking conditions>
The film after drying was heated at 10 ° C./min in an electric furnace at normal pressure and air atmosphere, and baked at 150 ° C. for 3 minutes. After firing, it was allowed to cool naturally and cooled to room temperature.
As a result of obtaining the maximum film thickness, the aperture ratio, the line width, the average area of the pores, the average maximum ferret diameter of the pores, the surface resistivity, and the total light transmittance of the conductive film thus obtained. It was street. In addition, as a result of evaluating the adhesion of the obtained conductive film and the degree of shrinkage of the film, the results are shown in Table 2.

(Comparative Example 2)
A conductive film was obtained in the same manner as in Comparative Example 1 except that the cyclohexane solution (b) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 1. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Comparative Example 3)
A conductive film was obtained in the same manner as in Comparative Example 1 except that the cyclohexane solution (c) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 1. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Comparative Example 4)
A conductive film was obtained in the same manner as in Comparative Example 1 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 1. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Comparative Example 5)
A conductive film was obtained in the same manner as in Comparative Example 2 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 2. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.

(Comparative Example 6)
A conductive film was obtained in the same manner as in Comparative Example 3 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 3. The results of evaluating the physical properties of the obtained conductive film are shown in Table 2.
In addition, the meaning of the item used in Table 2 is as follows.
Drying under wet conditions: Dry firing by blowing humidified air (relative humidity 70%) at a flow rate of 1.6 m / min for 10 minutes in an atmosphere of 23 ° C. and relative humidity 70%: film formation and drying The baking process performed after performing, ie, an infrared irradiation process, or the baking process at high temperature is represented.
Infrared: Five infrared heaters ZKC2000 (manufactured by Heraeus) having a peak wavelength of 1.22 μm were arranged at intervals of 4 cm and irradiated with infrared rays. The distance between the coating film and the heater was 5 cm, the watt density was adjusted to 160 kW / m ^2, and irradiation was performed for 2 seconds.
High-temperature firing: Increased temperature at 10 ° C / min in an electric furnace at normal pressure and air atmosphere, and fired film shrinkage at high temperature (150 ° C): degree of film shrinkage

(Formulation example 4)
Using a conductive fine particle dispersion solution, the weight concentration of silver was 310.632 mg / ml (corresponding to 29.130% by mass with respect to 100% by mass of cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10 (manufactured by Nikko Chemicals Co., Ltd.) as a weight concentration, a cyclohexane solution (d) of 9.2774 mg / ml (corresponding to 0.8700% by mass with respect to 100% by mass of the cyclohexane solution) was prepared. Table 3 summarizes the formulation.

(Formulation example 5)
Using a conductive fine particle dispersion solution, the weight concentration of silver was 315.489 mg / ml (corresponding to 29.130% by mass with respect to 100% by mass of the cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10, manufactured by Nikko Chemicals Co., Ltd., as the weight concentration, 7.0668 mg / ml (corresponding to 0.6525% by mass with respect to 100% by mass of the cyclohexane solution), and the near-infrared absorbing dye as the weight concentration is 2.355561 mg / ml. A cyclohexane solution (e) of ml (corresponding to 0.217500 mass% with respect to 100 mass% of cyclohexane solution) was prepared. Table 3 summarizes the formulation.

(Formulation example 6)
Using a conductive fine particle dispersion, the weight concentration of silver was 320.500 mg / ml (corresponding to 29.130% by mass with respect to 100% by mass of the cyclohexane solution), NIKKOL Decaglyn 7-OV (polyglyceryl heptaoleate- 10 (manufactured by Nikko Chemicals Co., Ltd.) as a weight concentration of 4.7860 mg / ml (corresponding to 0.4350% by mass with respect to 100% by mass of cyclohexane solution), and a near infrared absorbing dye as a weight concentration of 4.7860 mg / ml. A cyclohexane solution (f) of ml (corresponding to 0.43500 mass% with respect to 100 mass% of cyclohexane solution) was prepared. Table 3 summarizes the formulation.
The abbreviations used in Table 3 are the same as the abbreviations in Table 1.

(Comparative Example 7)
<Film forming conditions>
1.6 ml of cyclohexane solution (d) is set on a 5 cm square PET film substrate (trade name “Lumirror U34”, double-sided easy-adhesion treated PET, manufactured by Toray Industries, Inc.) so that the film thickness after drying is about 1 μm. A bar coater was applied, and dried (air-dried) at room temperature and normal pressure to form a film.
<Drying conditions>
It was dried (air-dried) at room temperature and normal pressure.
<Infrared irradiation conditions>
The film after drying was irradiated with infrared rays by arranging five infrared heaters ZKC2000 (manufactured by Heraeus) having a peak wavelength of 1.22 μm at intervals of 4 cm. The distance between the coating film and the heater was 5 cm, the watt density was adjusted to 160 kW / m ^2, and irradiation was performed for 2 seconds.
As a result of obtaining the maximum film thickness, the aperture ratio, the line width, the average area of the pores, the average maximum ferret diameter of the pores, the surface resistivity, and the total light transmittance of the conductive film thus obtained. It was street. In addition, as a result of evaluating the adhesion of the obtained conductive film and the degree of shrinkage of the film, the results are shown in Table 4.

(Comparative Example 8)
A conductive film was obtained in the same manner as in Comparative Example 7 except that the cyclohexane solution (e) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 7. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 9)
A conductive film was obtained in the same manner as in Comparative Example 7 except that the cyclohexane solution (f) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 7. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 10)
<Film forming conditions>
1.6 ml of cyclohexane solution (d) is applied onto a 5 cm square PET film (trade name “Lumirror U34”, double-sided easy-adhesion treated PET, manufactured by Toray Industries, Inc.) substrate, dried (air-dried) at room temperature and normal pressure, and manufactured. Filmed.
<Drying conditions>
It was dried (air-dried) at room temperature and normal pressure.
<Baking conditions>
The film after drying was heated at 10 ° C./min in an electric furnace at normal pressure and air atmosphere, and baked at 150 ° C. for 3 minutes. After firing, it was allowed to cool naturally and cooled to room temperature.
As a result of obtaining the maximum film thickness, the aperture ratio, the line width, the average area of the pores, the average maximum ferret diameter of the pores, the surface resistivity, and the total light transmittance of the conductive film thus obtained. It was street. In addition, as a result of evaluating the adhesion of the obtained conductive film and the degree of shrinkage of the film, the results are shown in Table 4.

(Comparative Example 11)
A conductive film was obtained in the same manner as in Comparative Example 10 except that the cyclohexane solution (e) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 10. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 12)
A conductive film was obtained in the same manner as in Comparative Example 10 except that the cyclohexane solution (f) was used, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 10. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 13)
A conductive film was obtained in the same manner as in Comparative Example 10 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 10. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 14)
A conductive film was obtained in the same manner as in Comparative Example 11 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 11. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.

(Comparative Example 15)
A conductive film was obtained in the same manner as in Comparative Example 12 except that baking was performed at 150 ° C. for 30 minutes, and the physical properties of the conductive film were evaluated in the same manner as in Comparative Example 12. Table 4 shows the results of evaluating the physical properties of the obtained conductive film.
The meanings of items used in Table 4 are the same as those in Table 2.

From the results of Examples and Comparative Examples, the following was found.
When drying is performed under wet conditions and firing is performed by infrared irradiation, the surface resistivity and the total light transmittance are compared with the case where any of them is not performed or neither is performed. In both cases, an excellent conductive film was obtained. Further, when drying was performed under wet conditions and baking was performed by irradiation with infrared rays, the adhesion to the substrate was good, and the shrinkage of the film was sufficiently suppressed. From these things, by applying the organic solvent dispersion to the substrate and forming the conductive film having a pattern and the step of irradiating infrared rays in this order, the conductive film obtained is made conductive. It has been found that it is excellent in light transmittance and can be excellent in other physical properties.
Although the difference between these examples and comparative examples is slight in numerical values, it can be said to be a sufficiently significant difference in the field of use as a transparent conductive film, etc., and the effect is remarkable. It can be evaluated that it is.
In the above examples, silver is used as the conductive substance and a near infrared absorbing dye is used as the infrared absorber, but the mechanism capable of forming a film by infrared irradiation uses conductive fine particles to perform the infrared irradiation step. In all cases, the same applies. Furthermore, the mechanism by which the infrared absorber irradiated with infrared rays absorbs infrared rays and generates heat is the same when conducting the infrared irradiation step using conductive fine particles and infrared absorbers. Therefore, from the results of the above-mentioned examples and comparative examples, the present invention can be applied in various technical forms of the present invention and in various forms disclosed in the present specification, and advantageous effects can be exhibited. I can say that.

11, 21: substrate 12, 22: coating film (coated organic solvent dispersion)
13: Water droplet 14: Hole portion 15: Mesh-like line portion 20: Peltier element

Claims (5)

A method for producing a conductive film on a substrate using an organic solvent dispersion containing conductive fine particles,
The manufacturing method includes: applying a conductive film having a pattern on a substrate by applying an organic solvent dispersion to a substrate, forming a conductive film having a pattern, and irradiating infrared rays in this order. A method for producing a conductive film, comprising: forming a conductive film. The step of forming the conductive film having the pattern includes a step of evaporating the organic solvent while the organic solvent dispersion coated on the substrate is condensed on the surface of the coating film. A method for producing a conductive film. The method for producing a conductive film according to claim 1, wherein the organic solvent dispersion includes an infrared absorber. A conductive film manufactured by the method according to claim 1. The conductive film according to claim 4, wherein the conductive film is used for digital paper.

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