JP2014191894A - Transparent electroconductive film and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal nanowire-containing transparent electroconductive film unlikely to entail a surface resistance gain due to variations over time in a high-temperature/high-humidity environment, above all a metal nanowire-containing transparent electroconductive film unlikely to entail, even in a case where a transparent electroconductive layer including a metal nanowire as a main component is formed atop a film substrate or where a transparent protective film is laminated thereon prior to being subjected to a heating process, a surface resistance gain due to variations over time in a high-temperature/high-humidity environment.SOLUTION: A transparent electroconductive film possessing, atop a film substrate, a transparent electroconductive layer including metal nanowires as a main component and a transparent protective film where the transparent protective layer consists of a transparent electroconductive film consisting of a protective layer-forming coating material including gallic acid or propyl gallate is unlikely to entail a surface resistance gain due to variations over time in a high-temperature/high-humidity environment and is capable of realizing a high reliability.

Description

  The present invention relates to a transparent conductive film containing metal nanowires and a touch panel using the same.

  A transparent conductive film in which a transparent conductive layer is formed on a transparent film substrate is widely used as an important functional member in a display element using light emitting and receiving functions. In particular, by forming a transparent conductive layer into a pattern, a transparent conductive sheet in which a large number of conductive regions are arranged on a sheet-like transparent substrate and have a function such as an electrode or a switch is made thin and small in size. It is an indispensable member for high functionality.

  Generally, the pattern of the transparent conductive layer is a method of forming an ITO layer or a zinc oxide layer on a transparent substrate by vapor deposition or sputtering, and then patterning by dry etching such as plasma, or using a positive / negative resist in combination. Is adopted. However, vapor deposition and sputtering require a large amount of equipment and energy, and when a plastic film is used as a transparent substrate in order to provide flexibility, which is one of advanced functions, the heat during vapor deposition and sputtering. This sometimes causes problems such as distortion of the plastic film. Therefore, there is a need for a transparent conductive sheet that does not require much heat energy, has a simple manufacturing apparatus, and has high productivity.

  As a method that requires less thermal energy and has a simple manufacturing apparatus, a method of obtaining a transparent conductive layer by applying a coating solution of conductive nanowires such as metal and carbon to a substrate has been studied. In particular, metal nanowires are attracting attention as materials capable of forming a transparent electrode having a low specific resistance and a lower surface resistance.

  In recent years, display elements used in various fields including various mobile devices have been reduced in weight, and the display element substrate is also required to shift from glass to plastic. The transparent conductive film using metal nanowires is coated with the metal nanowire dispersion on the substrate, then pressurizes the coated surface as necessary to increase the contact point, and then the transparent protective solution is applied to the metal nanowire coated surface. It is obtained by immobilizing the metal nanowire-coated surface by applying to the surface. Transparent conductive films using metal nanowires coated on plastic films are highly flexible and do not generate cracks like ITO films, so they can be used in fields that require highly flexible electrodes. It has the advantage that the product life can be extended.

  Products using transparent conductive films are diversifying for mobile and in-vehicle use, and the environmental characteristics required for transparent conductive films are becoming more severe. In this regard, in the case of a transparent conductive film containing metal nanowires, there has been a problem that the surface resistance value tends to increase due to deterioration with time under high temperature and high humidity.

  For the improvement, it has been proposed to add to the conductive layer a compound that forms a protective film by bonding to the metal surface to prevent corrosion of the metal nanowires. (Patent Document 1) For example, benzotriazole (BTA) is a general organic corrosion inhibitor for copper or copper compounds, and triazine is a hydrogen sulfide scavenger for making metals difficult to be sulfided. It has been proposed that inclusion in a conductive layer is also effective.

  However, in the transparent conductive film containing the conventional metal nanowire having the proposed configuration, there is a problem that surface resistance is likely to increase due to a change with time under high temperature and high humidity. Further, when the film is annealed, there is a particular problem that the surface resistance is likely to increase remarkably due to a change with time under high temperature and high humidity.

Special table 2009-505358

  It is an object of the present invention to provide a transparent conductive film containing metal nanowires that hardly cause an increase in surface resistance due to changes with time under high temperature and high humidity. In particular, even when a heating process is performed after forming a transparent conductive layer mainly composed of metal nanowires on a film substrate or after laminating a transparent protective layer, the surface resistance increases due to aging under high temperature and high humidity. The object is to provide a transparent conductive film containing difficult metal nanowires.

In view of the above situation, as a result of intensive studies, the present inventors have found that the reliability under high temperature and high humidity can be dramatically improved by using a specific transparent protective layer composition, and the present invention is completed. It came to.
Means for solving the above problems are as follows.

  (1) A transparent conductive layer mainly composed of metal nanowires and a transparent protective layer are provided on a film substrate, and gallic acid or propyl gallate is contained in the transparent protective layer. Transparent conductive film.

  (2) The transparent conductive film according to (1), wherein the transparent conductive layer mainly composed of metal nanowires is formed by applying a coating liquid mainly composed of metal nanowires on a substrate.

  (3) The transparent conductive film according to (1) or (2), wherein the transparent conductive layer containing the metal nanowires as a main component is patterned.

  (4) The step of patterning the transparent conductive layer containing the metal nanowires as a main component forms a layer having a negative patterned adhesive region on the support, and the film substrate and the support. Bonding the transparent conductive layer and the adhesive region of the layer having the adhesive region so that they are in close contact with each other, peeling the support from the film base, and the adhesive region of the layer having the adhesive region Produced in the process of laminating a transparent protective layer after forming the pattern of the transparent conductive layer on the film substrate by moving the transparent conductive layer of the adhered part onto the adhesive region of the layer having the adhesive region The transparent conductive film according to any one of (1) to (3).

  (5) Any of the above (1) to (4), comprising a heating step after forming a transparent conductive layer mainly composed of metal nanowires on a film substrate or after laminating a transparent protective layer The transparent conductive film described in 1.

  (6) The transparent conductive film according to any one of (1) to (5), wherein the metal nanowire is a silver nanowire.

  According to the present invention, whether a heating step is included after forming a transparent conductive layer mainly composed of metal nanowires on a film substrate or after laminating a transparent protective layer without impairing initial characteristics as a transparent conductive film. Regardless of this, it is possible to effectively suppress an increase in surface resistance with time under high temperature and high humidity.

(A) It is sectional drawing of the film base | substrate which formed the transparent conductive layer in this invention, (b) It is sectional drawing of the film base | substrate which formed the protective layer on the transparent conductive layer in this invention. It is sectional drawing of the support body which has the negative pattern heat-sensitive adhesive in this invention. It is a schematic cross section of the heating and pressure bonding process of the support body which has a film base with a transparent conductive layer in this invention, and the negative-patterned heat-sensitive adhesive. It is a schematic cross section of the peeling process of the support body which has the film base with a transparent conductive layer in this invention, and the negative-patterned heat-sensitive adhesive. It is sectional drawing after apply | coating the coating material for protective layers on the patterned transparent conductive layer in this invention, and forming a protective layer. It is a top view of the pattern for X axes of the transparent conductive layer for touchscreens formed with the method of this invention. It is a top view of the pattern for Y axes of the transparent conductive layer for touch panels formed by the method of this invention. It is a top view of the negative pattern for X-axis for the heat sensitive adhesive layers formed on a support body in this invention. It is a top view of the negative pattern for Y-axis for the heat sensitive adhesive layers formed on a support body in this invention. It is sectional drawing which shows an example of the transparent conductive film laminated body by which the transparent conductive layer of the film base | substrate which formed the transparent conductive layer in this invention, and the double-sided adhesive sheet were laminated | stacked. It is sectional drawing which shows an example of the transparent conductive film laminated body by which the transparent conductive layer of the film base | substrate which formed the transparent conductive layer in this invention, and the double-sided adhesive sheet were laminated | stacked. It is sectional drawing which shows an example of the transparent conductive film laminated body by which the transparent conductive layer of the film base | substrate which formed the transparent conductive layer in this invention, and the double-sided adhesive sheet were laminated | stacked. It is a conceptual diagram of the electrostatic capacitance type touch panel apparatus using the transparent conductive film laminated body on which the transparent conductive film of this invention and the double-sided adhesive sheet for fixation were laminated | stacked.

The transparent conductive film of the present invention is a transparent conductive film in which a transparent conductive layer mainly composed of metal nanowires and a transparent protective layer are sequentially laminated on a film base, and gallic acid or gallic acid propylene is used as the transparent protective layer. A transparent protective layer formed from a coating for protective layer containing The conductive layer is patterned as necessary and is suitably used for a touch panel sensor or the like.
Hereinafter, the present invention will be described in detail.

  The transparent conductive film of the transparent conductive film of the present invention has a transparent conductive layer formed on a transparent film substrate, or an arbitrary transparent conductive layer pattern formed on a transparent film substrate.

  As a method for forming a transparent conductive layer containing a resin and metal nanowires on a transparent film substrate, it can be produced by applying and drying a transparent conductive paint containing metal nanowires on the transparent film substrate. .

  Even if the conductive material contained in the transparent conductive layer itself is not transparent, use it if the metal nanowires that form the transparent conductive layer by controlling the shape and content are the main agent. Can do. The transparent conductive layer of the present invention preferably has a surface resistivity of 0.01Ω / □ to 1000Ω / □, has high transparency in the visible light region, and has a total light transmittance of 80% or more. preferable. The transparent conductive film which has a transparent conductive layer containing a metal nanowire on a transparent film base as a more preferable form below is demonstrated.

[Metal nanowires]
The metal nanowires contained in the transparent conductive film used for the transparent conductive film of the present invention are fibrous, and among them, there is no branch, it is easy to loosen, and it is easy to obtain a uniform distribution density of the fibrous substance, and a large opening It is preferable to form the film and realize a good light transmittance. The metal nanowire of the present invention is a fine conductive substance having a thin rod shape with a straight line or a curve, a metal material, and a diameter of nanometer. If the fine conductive material is in the form of a wire, they are entangled with each other to form a mesh, so that a good electrical conduction path can be formed even with a small amount of conductive material. The resistance value of the layer can be further reduced, which is preferable. Furthermore, when such a mesh-like shape is formed, since the opening of the gap portion of the mesh is large, even if the wire-like conductive substance itself is not transparent, a good transparency as a coating film is achieved. Is possible.

  Specific examples of the metal of the metal nanowire include iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, osmium, iridium, platinum, and gold. From the viewpoint of conductivity, copper, silver Platinum and gold are preferable, and platinum plated or gold plated silver is more preferable. At least one cross-sectional dimension of the metal nanowire is preferably less than 500 nm, more preferably less than 200 nm, and even more preferably less than 100 nm. The metal nanowire preferably has an aspect ratio exceeding 10. The aspect ratio is more preferably more than 50 and still more preferably has an aspect ratio exceeding 100. The shape and size of the metal nanowire can be confirmed with a scanning electron microscope or a transmission electron microscope.

  Metal nanowires can be prepared by methods known in the art. For example, a method of reducing silver nitrate in a solution, a method in which an applied voltage or current is applied to the precursor surface from the tip of the probe, a metal nanowire is drawn at the probe tip, and the metal nanowire is continuously formed, etc. (Japanese Patent Laid-Open No. 2004-223893). As a method for reducing silver nitrate in a solution, more specifically, silver nanowires are synthesized by liquid phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Is possible. For example, Xia, Y. et al. etal. , Chem. Mater. (2002), 14, 4736-4745 and Xia, Y. et al. etal. , Nano letters (2003) 3 (7), 955-960, but is not particularly limited to the methods described therein. Such a conductive metal nanowire has a state in which the metal nanowires are entangled with each other while maintaining an appropriate interval on the transparent substrate, and a substantially transparent conductive network is possible by forming a conductive network. Specific metal types, shaft lengths, aspect ratios, and the like may be appropriately determined according to the purpose of use.

[Formation of transparent conductive film containing metal nanowires]
The transparent conductive film containing metal nanowires used in the present invention can be produced by applying a transparent conductive paint in which metal nanowires are dispersed on a transparent film substrate.
The dispersion liquid of metal nanowires, which is the transparent conductive paint, may not contain a binder resin in terms of improving the conductive performance. In the conductive layer, the contact between the metal nanowires is not inhibited unless a binder resin is used. Therefore, the electrical conductivity between metal nanowires is ensured, and the electrical resistance value of the obtained conductive layer can be kept lower.

Thus, after forming a transparent conductive layer on a transparent film base | substrate using the transparent conductive coating material containing metal nanowire, and forming a pattern as needed, it consists of transparent resin for fixing a transparent conductive layer A transparent protective layer is laminated and solidified to form a protective layer.
From this, it is preferable to go through the following steps for patterning.
(1) Step of forming a peelable transparent conductive layer on a film substrate (2) Applying a protective layer coating to the entire surface of the film substrate on which the transparent conductive layer pattern is formed, and applying the transparent conductive layer to the film substrate Immobilizing on the top

[Preparation of transparent conductive paint containing metal nanowires]
A transparent conductive layer is formed on a transparent film substrate using a dispersion liquid in which metal nanowires are dispersed to produce a transparent conductive film. The liquid that is a dispersion medium for forming the transparent conductive paint that is the metal nanowire dispersion liquid used for this purpose is not particularly limited, and various known dispersion media can be used. For example, saturated hydrocarbons such as hexane, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol, propanol, and butanol, ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and diisobutyl ketone , Esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane and diethyl ether, amides such as N, N-dimethylformamide, N-methylpyrrolidone (NMP) and N, N-dimethylacetamide, ethylene chloride And halogenated hydrocarbons such as chlorobenzene. Moreover, a dispersing agent can also be used according to the kind of dispersion medium. Among these, polar dispersion media are preferable, and those having an affinity for water such as alcohols such as methanol and ethanol, and amides such as NMP have good dispersibility without using a dispersant. It is preferable. These liquids can be used singly or as a mixture of two or more.

  Water can also be used as a dispersion medium. When water is used, if the surface of the transparent film substrate is hydrophobic, it is easy to repel water, and it is difficult to obtain a uniform film when applying the transparent conductive paint. In such a case, a uniform film can be obtained by mixing and adding an alcohol to water, or selecting and adding a surfactant that improves wettability to a hydrophobic transparent film substrate. It is also possible to provide an easy adhesion layer for improving wettability to the transparent film substrate.

  The amount of the liquid as a dispersion medium to be used is not particularly limited, and the metal nanowire dispersion liquid may have a viscosity suitable for coating. For example, with respect to 100 parts by weight of the metal nanowire material, the liquid can be set in a wide range of about 100 to 100,000 parts by weight. It can be appropriately selected depending on the case.

  The process of fixing the conductive layer with the resin in the coating for the protective layer without reducing the conductivity of the coating film on the film substrate and the coating film peelability from the film substrate required for patterning as required. A resin can be included as long as the amount is not impaired, and the type and amount thereof can be appropriately selected within the range in which the above characteristics are obtained.

In the above addition amount range, the metal nanowire dispersion may contain the resin and other additives in order to control viscosity, prevent corrosion, improve adhesion to the substrate, and control the dispersion of the metal nanowires. Examples of suitable additives and binders include carboxymethylcellulose (CMC), 2-hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), methylcellulose (MC), polyvinyl alcohol (PVA), tripropylene glycol (TPG), And xanthan gum (XG), and surfactants such as ethoxylates, alkoxylates, ethylene oxide, and propylene oxide, and copolymers thereof, sulfonates, sulfates, disulfonates, sulfosuccinates, phosphate esters , And fluorine-based surfactants.
Furthermore, non-polymer organic compounds such as 2-alkoxyethanol, β-diketone and alkyl acetate can also be used as a film forming agent.

  The dispersion of the metal nanowires in the dispersion medium can be performed by applying a known dispersion technique to the mixture of the metal nanowires and the liquid that is the dispersion medium as necessary. However, in order to form a transparent conductive layer having good transparency and conductivity, the characteristics of the metal nanowire and its shape do not change significantly before and after the dispersion treatment, and the transparency when made into a transparent conductive layer is lost. It is important not to.

[Formation of transparent conductive film]
The transparent film substrate usable in the present invention mainly includes polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polyethylene, polypropylene, polystyrene and EVA, and vinyl resins such as polyvinyl chloride and polyvinylidene chloride. Films made of plastics such as polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, acrylic resin can be used, and among them, those having a total visible light transmittance of 70% or more are preferable. These may be colored to such an extent that they do not interfere with the object of the present invention, and can be used as a single layer, but may be used as a multilayer film in which two or more layers are combined. Furthermore, the surface which forms the transparent conductive film of a film base | substrate may be provided with the process layer which controls the adhesiveness with a transparent conductive layer optimally, and the hard-coat layer can also be provided in the back side. Among these films, a polyethylene terephthalate film and a polyethylene naphthalate film are preferable from the viewpoint of transparency, heat resistance, ease of handling, and cost, and a polyethylene terephthalate film is most suitable. The thickness of the transparent film substrate is preferably 5 μm to 300 μm because the handleability is poor when it is thin, and the transmittance of visible light decreases when it is thick. More preferably, 10 micrometers-250 micrometers are preferable, and 25 micrometers-200 micrometers are still more preferable.

In order to form a transparent conductive coating film on a transparent film substrate using the above raw materials, a dispersion containing metal nanowires, a dispersion medium, and a resin as required as shown in FIG. ) And dried to form a uniform conductive coating (2) on the transparent substrate.
As a coating method, a known coating method such as spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, or the like can be used.
If the film thickness of the transparent conductive layer is too thin, sufficient conductivity as a conductor tends not to be achieved, and if it is too thick, transparency tends to be impaired due to an increase in haze value, a decrease in total light transmittance, and the like. Usually, the thickness is adjusted appropriately between 10 nm and 10 μm. However, when the conductive material itself is not transparent like metal nanowires, the transparency can be easily lost by increasing the film thickness, and the conductive layer having a thinner film thickness. Is often formed. In this case, the conductive layer has a large number of openings, but when measured with a contact-type film thickness meter, the average film thickness is preferably 10 nm to 500 nm, more preferably 30 nm to 300 nm, and more preferably 50 nm to 150 nm. Is most preferred.

  In the method for producing a transparent conductive layer according to the present invention, in order to increase the conductivity of the transparent conductive layer formed on the transparent film substrate, the contact points at the intersections of the metal nanowires in the transparent conductive layer after coating formation are increased. At the same time, it is desirable to perform a pressurizing step for increasing the contact area and ensuring the contact.

  Specifically, the pressurizing step is a step of pressurizing the surface of the transparent conductive layer, and compresses the transparent conductive layer by applying pressure from directly above the transparent conductive layer in which metal nanowires are dispersed in a mesh shape. And increasing the contact points of the internal metal nanowires. By this step, the contact resistance between the metal nanowires can be lowered, and the surface resistance value of the conductive layer surface can be lowered.

This step is not particularly limited as long as it is a publicly known method for pressurizing the coating surface, but the layer obtained by coating is, for example, a transparent conductive layer disposed between two flat plates that can be pressurized, and fixed. Examples thereof include a flat plate pressing method in which pressure is applied for a period of time, a calendering method in which a transparent conductive layer is sandwiched between two pressurizable rolls, linearly pressed, and the entire surface is pressed by rotating the roll.
In calendering with a roll, the pressure for pressurizing the transparent conductive ^{layer, 500kN / m 2 ~50000kN / m} 2, preferably ^{1000kN / m 2 ~10000kN / m 2} , more preferably at 2000kN ^{/ m 2} ~5000kN ^/ m 2 is there.

[Application of protective layer paint (fixation of transparent conductive layer)]
After forming the transparent conductive layer on the film substrate, or after forming a desired pattern as necessary, the entire surface of the transparent conductive layer formed on the film substrate, or a transparent transparent layer having a patterned transparent conductive layer The protective layer coating is applied to the entire surface of the film substrate partially covered with the conductive layer.

  The coating process of the protective layer coating is performed on the entire surface of the uniform transparent conductive layer or on the entire surface of the substrate having a patterned transparent conductive layer formed in the process described below and partially coated with the transparent conductive layer. The coating is applied to the protective layer, the solvent component is dried, the resin component contained is cured, and a transparent protective layer is formed. The surface of the transparent conductive layer is covered and protected by this process, and the coating for the protective layer reaches the film substrate while filling the gaps of the mesh formed by the metal nanowires in the transparent conductive layer, and is transparent when cured. The entire conductive layer is firmly fixed on the substrate to form a transparent conductive film.

  A possible material or combination of materials for the binder resin used for fixing the transparent conductive layer is described below. Immobilization with these binder resins is a polymerization of monomers or oligomers (10 to 100 monomers) contained in the protective layer coating by light irradiation or heating, or the resin in the protective layer coating is Crosslinking is performed by drying and heating to form a solid polymer matrix, or the binder resin in the solvent is formed by forming a crosslinked coating film by removing the solvent, but the coating film is not necessarily polymerized, crosslinked. It is not limited to what was hardened and formed through the process. However, in terms of durability and scratch resistance of the coating film, it must be fixed through polymerization of monomers by visible light or ultraviolet light, electron beam, heating, etc., or crosslinking of a polymer compound by a crosslinking agent. Is preferred.

  The polymer used as the binder preferably has a polar functional group bonded to the carbon skeleton. Examples of the polar functional group include a carboxyl group, an ester group, a ketone group, a nitrile group, an amino group, a phosphoric acid group, a sulfonyl group, a sulfonic acid group, a polyalkylene glycol group, and an alcoholic hydroxyl group. Examples of polymers useful as binders include acrylic resins, alkyd resins, polyurethanes, acrylic urethanes, polycarbonates, polyesters, polystyrenes, polyacetals, polyamides, polyvinyl alcohol, polyvinyl acetate, and cellulose.

  Examples of polymerizable monomers or oligomers that are monomers include methyl acrylate, methyl methacrylate, methoxypolyethylene glycol methacrylate, glycidyl acrylate, ethylene oxide-modified phosphate acrylate, urethane acrylate, polyethylene glycol methacrylate, polybutadiene acrylate, polyester Acrylate and methacrylate type monomers and oligomers represented by acrylate and the like; mono (2-methacryloyloxyethyl) acid phosphate, acrylic acid, methacrylic acid, itaconic acid, acrylonitrile, methacrylonitrile, styrene, vinyltoluene, etc. Vinyl monomers; epoxide compounds such as bisphenol A diglycidyl ether.

  One or more of the above-mentioned polymer binders (polymer, monomer or oligomer) are dissolved or diluted with an organic solvent as necessary to prepare a liquid having a viscosity of 25 cps or less, preferably 10 cps or less. When the viscosity of this liquid is higher than 25 cps, the liquid does not sufficiently penetrate into the coating film so as to reach the film substrate when impregnated with the coating film, and the intended effect of improving the adhesion and film strength cannot be obtained. Moreover, when the liquid has a high viscosity, it becomes easy to form an insulating layer on the transparent conductive layer, and in that case, the conductivity is significantly lowered.

  The organic solvent used for dissolution or dilution is not particularly limited, and in addition to various organic solvents as exemplified for the coating film forming process, a liquid organic compound used as a film forming agent in the coating film forming process, and water are also used as the solvent. It can be used.

  If necessary, the impregnation liquid includes a curing catalyst (in the case of heat curing), a photopolymerization initiator (in the case of ultraviolet curing), a crosslinking agent, a hydrolysis catalyst (eg, acid), a surfactant, a pH adjuster, and the like. Can be added.

  Examples of suitable solvents include water, alcohols, ketones, cyclic ether compounds (such as tetrahydrofuran), hydrocarbons (eg, cyclohexane), or aromatic solvents (such as benzene, toluene, xylene). More preferably, the solvent is volatile and has a boiling point of 200 ° C. or lower, 150 ° C. or lower, or 100 ° C. or lower.

  The protective layer coating material of the present invention contains gallic acid or propyl gallate. By containing these, it is possible to suppress an increase in surface resistance of the conductive film under high temperature and high humidity. As addition amount of a gallic acid or a propyl gallate, 1-100 mass parts is preferable with respect to 100 mass parts of solid content of the binder resin used for the coating material for protective layers, and 5-80 mass parts is more preferable. By setting it as the said compounding quantity, it becomes easy to obtain the surface resistance raise inhibitory effect, and it becomes easy to maintain the coating-film intensity | strength as a protective layer.

  Moreover, as long as the function as a protective layer is not inhibited, a crosslinking agent, a polymerization initiator, an ultraviolet absorber, a surfactant, and those having similar effects may be included as necessary.

  The mechanism by which gallic acid or propyl gallate is contained in the protective layer can suppress the increase in surface resistance over time of the conductive film under high temperature and high humidity has not been elucidated, but as follows Estimated.

  The surface of the conductive layer in which the metal nanowires are dispersed exposes a part of the metal nanowire from the surface of the binder resin for the conductive layer so that electrical connection can be obtained from the coating film surface. Further, the protective layer covering the conductive layer needs to be a thin film so as not to hinder the electrical connection from the coating film surface. For this reason, it is presumed that the oxidation of the metal nanowire progresses with time by being kept in high temperature and high humidity for a long time, and the contact resistance inhibition is proceeding.

  For example, even when a silver nanowire layer contains a sulfidizing agent or the like for the purpose of preventing corrosion, if the protective layer does not contain gallic acid or propyl gallate, the conductive film under high temperature and high humidity over time Since the increase in surface resistance cannot be suppressed, it is considered that the optimal antioxidant function was expressed by including gallic acid or propyl gallate in the protective layer.

  It is estimated that gallic acid is a solid at room temperature and decarboxylates when heated to act as pyrogallol and act as a reducing agent. Alternatively, gallic acid or propyl gallate is presumed to act as a reducing agent due to the influence of moisture under high temperature and high humidity over a long period of time.

  The method for forming the protective layer is not particularly limited as long as it is a known wet coating method. Specifically, spray coating, bar coating, roll coating, die coating, ink jet coating, screen coating, dip coating and the like can be mentioned.

  When forming a protective layer while impregnating the transparent conductive layer with the coating for the protective layer, if the protective layer after coating and drying is too thin relative to the transparent conductive layer before coating, scratch resistance and abrasion resistance The function as a protective layer such as weather resistance is lowered, and if it is too thick, the contact resistance as a conductor increases.

  When the film thickness of the transparent conductive layer is formed in the range of 50 to 150 nm, the coating thickness of the transparent conductive layer is preferably 30 to 150 nm after coating and drying. In consideration of the above, the surface resistivity, haze, etc. can be adjusted so as to achieve predetermined values. 40 to 175 nm is more preferable, and 50 to 150 nm is most preferable. The thickness of the protective layer coating after drying depends on the thickness of the transparent conductive layer, but if it is 30 nm or more, the protective function of the protective layer tends to work better, and the thickness is 150 nm or less. When it is, it exists in the tendency which can ensure more favorable electroconductive performance.

[Pattern of transparent conductive layer]
Unlike the case where a uniform conductive layer is formed on a film substrate, when forming a pattern of a transparent conductive film used for a capacitive touch panel, it is necessary to avoid aggregation of metal nanowires and between metal nanowires. There is a need to ensure an electrical contact, and the paint for forming the transparent conductive layer often cannot contain a sufficient resin component for direct pattern formation by a printing method. For this reason, the solid content concentration is extremely low and the viscosity is low, and printing for pattern formation is often difficult. In such a case, a uniform transparent conductive layer is formed in advance on the transparent film substrate, and unnecessary transparent conductive layer portions are deleted by various methods, or conversely, necessary patterns are cut out to form a pattern. A transparent conductive layer can be obtained. That is, after forming a uniform transparent conductive layer containing silver nanowires on a transparent film substrate, it is necessary to add a step of patterning the transparent conductive layer.

The step of patterning the transparent conductive layer on the film substrate can be performed after the step of fixing the transparent conductive layer on the substrate, but after the step of forming the transparent conductive layer on the substrate by coating. If the transparent conductive layer is fixed on the substrate before the step, patterning is easy and there are many methods that can be applied. Further, after patterning, a transparent film substrate with a more reliable transparent conductive layer after patterning can be obtained by applying a protective layer coating to the entire surface of the transparent film substrate partially covered with the patterned transparent conductive layer. It is preferable because it can be fixed to the head.
As a specific method for forming the patterned transparent conductive layer on the film substrate, any method can be applied from patterning by laser beam, photoetching, etc. in addition to the above method. However, since it can be processed continuously using a coating process, it does not require light irradiation or masking, and it does not require wet processing such as etching. Using a peeling base material in which a negative pattern is formed with an agent coating, peeling off unnecessary portions of the transparent conductive layer formed on the substrate to form a desired patterned transparent conductive layer Is preferred.

Hereinafter, a method for patterning a transparent conductive layer using a peeling substrate having a negative patterned adhesive layer will be described.
[Formation of patterned transparent conductive layer]
The following method is to obtain a patterned transparent conductive layer by removing unnecessary portions from a previously prepared uniform transparent conductive layer using a peeling substrate having an adhesive layer on which a negative pattern is formed. Conversely, a necessary pattern may be cut out from the uniform transparent conductive layer using a patterned adhesive layer, but the former method in which the adhesive layer does not remain after patterning is preferred.

That is, a method of forming a transparent conductive layer patterned using a transparent conductive layer containing silver nanowires and finally producing a transparent conductive film having a patterned transparent conductive layer fixed to a transparent film substrate Can include a method using the following steps.
(1) Step of forming a peelable transparent conductive layer on a film substrate (2) Step of forming a negative patterned heat-sensitive adhesive layer on a support (3) The film substrate and the support (4) peeling the support from the film substrate and bonding the transparent conductive layer to the heat-sensitive adhesive layer in a portion where the transparent conductive layer and the heat-sensitive adhesive layer are in close contact with each other. Step of forming a transparent conductive layer pattern on the film substrate by transferring the layer onto the heat-sensitive adhesive layer (5) Applying a protective layer coating to the entire surface of the film substrate on which the transparent conductive layer pattern is formed This is a step of applying and fixing the transparent conductive layer on the substrate.

The part related to patterning of the transparent conductive layer in the steps (2) to (4) will be described below.
[Preparation of Support (Peeling Substrate) Having a Patterned Heat-Sensitive Adhesive Layer (Step (2))]
A substrate for peeling is prepared in order to partially peel the transparent conductive layer formed on the film substrate from the film substrate. As shown in FIG. 2, the base material for peeling used in the present invention has a heat-sensitive adhesive layer (4) having a negative pattern on the support (3). The base material for peeling has a negative adhesive pattern opposite to the desired conductive pattern to be formed on the film substrate by applying a heat-sensitive adhesive layer coating containing a heat-sensitive adhesive and a solvent on the support (3). It can form by forming and apply | coating.

  The thermosensitive adhesive does not exhibit any tackiness at room temperature, but develops tackiness when heated. As the heat-sensitive adhesive of the heat-sensitive adhesive layer formed on the support, there is an affinity for both the transparent conductive layer formed on the transparent film substrate and the support, and the heat-sensitive adhesive that can strongly bond both. The adhesive is not particularly limited, and various known heat-sensitive adhesives can be used. However, the temperature at which tackiness develops can penetrate into the gap between the conductive materials of the transparent conductive layer and become conductive. It is preferable that the adhesiveness is exhibited at a temperature at which the material adheres well and does not greatly exceed the glass transition temperature of the transparent film substrate. Moreover, when peeling a support body at about normal temperature after a heating, it is preferable to show strong adhesive force to both metal nanowire and a support body.

  Examples of such heat-sensitive adhesives include polyurethane adhesives, polyester adhesives, vinyl acetate (vinyl chloride / vinyl acetate copolymer) adhesives, and acrylic adhesives. Among them, a heat-sensitive adhesive having a glass transition temperature Tg of room temperature or higher, an acid group such as a carboxylic acid group or a sulfonic acid group, and mainly composed of an amorphous polyester resin or a polyester polyurethane resin is preferable. Is preferably in the range of 20-100 ° C. Further, for the purpose of manipulating the heat sensitive temperature, an appropriate amount of resins having compatibility with the main agent and having different glass transition temperatures Tg may be blended.

  If necessary, an anti-blocking agent can be added to the heat-sensitive adhesive. Examples thereof include inorganic fine particles such as barium sulfate and resin fine particles such as polyethylene or polypropylene. They can be added singly or in combination, and their addition amount and particle size can be freely selected within a range that does not impair the function as a heat-sensitive adhesive.

  Any non-corrosive solvent can be used as the solvent used in the heat-sensitive adhesive layer coating as long as the binder resin used in the heat-sensitive adhesive is dissolved or dispersed well. Examples of more suitable solvents include water, alcohols, ketones, cyclic ether compounds such as tetrahydrofuran, hydrocarbons such as cyclohexane, or aromatic solvents such as benzene, toluene, and xylene. Further, the solvent is volatile, preferably has a boiling point of 200 ° C. or lower, more preferably 150 ° C. or lower, and further preferably has a boiling point of 100 ° C. or lower.

  As the support used for the substrate for peeling in the present invention, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polyethylene, polypropylene, polystyrene and EVA, polyvinyl chloride, polyvinylidene chloride and the like are mainly used. A film made of a plastic such as vinyl resin, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, or acrylic resin can be used. Among these, those that do not cause thermal deformation in the step of bringing the transparent conductive layer and the heat-sensitive adhesive layer into close contact with each other and heat bonding are preferable.

  These supports may be colored to the extent that they do not interfere with the object of the present invention, and can be used as a single layer, but may be used as a multilayer film in which two or more layers are combined. Of these, a polyethylene terephthalate film is most suitable in terms of transparency, heat resistance, ease of handling, and cost. The thickness of the transparent plastic substrate is preferably 5 μm to 100 μm because if it is thin, the heat resistance is poor, and if it is thick, the heat capacity becomes large and a long heating time is required to develop tackiness by heating the heat-sensitive adhesive. More preferably, it is 10 micrometers-50 micrometers, and it is still more preferable that it is a film thickness of 15 micrometers-30 micrometers.

The heat-sensitive adhesive layer on the support is formed in a so-called negative pattern in which a desired transparent conductive pattern to be obtained on the substrate is inverted.
As a method for forming a negative pattern of an adhesive, a known printing method can be used, and a heat-sensitive adhesive layer that exhibits tackiness by heating is sufficient to adhere well to the transparent conductive layer on the film substrate in the next step. As long as the thickness of the heat sensitive adhesive can be formed, there is no particular limitation and a known method can be used. For example, a gravure printing method, an offset printing method, a gravure offset printing method, a screen printing method, an ink jet printing method and the like can be used. The thickness of the heat-sensitive adhesive layer is preferably 0.05 μm to 5.0 μm, more preferably 0.1 μm to 2.0 μm, and still more preferably 0.2 μm to 1.0 μm.

[Patterning process of transparent conductive layer]
The patterning process of the transparent conductive layer containing the metal nanowires used in the present invention is as follows: (3) the film substrate and the support, and the transparent conductive layer and the negative patterned heat-sensitive adhesive layer are mutually connected. (4) peeling the support from the film substrate and transferring the transparent conductive layer in close contact with the heat-sensitive adhesive layer onto the heat-sensitive adhesive layer. And a step of forming a pattern while leaving a desired transparent conductive layer on the film substrate. In the step of bonding, the film substrate provided with the transparent conductive layer and the peeling substrate which is a support provided with the heat-sensitive adhesive layer formed with the negative pattern are combined with the transparent conductive layer and the heat-sensitive adhesive layer. Are bonded and heated and pressurized so that they are in close contact with each other. In particular, when the transparent conductive layer does not contain a binder resin or is contained in a small amount, the heat-sensitive adhesive is softened by heating and pressurization of the heat-sensitive adhesive layer, and the metal nanowire network of the transparent conductive layer is softened. It penetrates and the heat-sensitive adhesive and the transparent conductive layer adhere.

  Then, after cooling the heat-sensitive adhesive layer of the bonded part to about room temperature, the support is peeled off from the film base, and the transparent conductive layer of the part bonded to the heat-sensitive adhesive layer is negatively patterned on the support By peeling and transferring onto the heat-sensitive adhesive layer, a positive pattern of the transparent conductive layer remains on the film substrate, and a desired transparent conductive layer pattern is completed on the film substrate.

  The bonding method used at the time of patterning the transparent conductive layer is not particularly limited as long as it does not cause thermal deformation of the substrate due to heating and pressurization at the time of bonding. For example, a flat plate laminating method in which a transparent conductive layer of the film substrate and a heat-sensitive adhesive layer on a support in the peeling substrate are arranged between two flat plates that can be heated and pressed, and heated and pressed for a certain time. And a film substrate (1) having the transparent conductive layer (2) between the nips of two roll pairs (5) and (6) which can be heated by either or both as shown in FIG. A roll laminating method or the like in which the support (3) having the heat-sensitive adhesive layer (4) is conveyed and sandwiched, heated, linearly pressed, and the entire surface is pressed by rotating the rolls (5) and (6). Can be mentioned.

  In particular, the latter roll laminating method enables continuous processing by roll-to-roll using a film substrate and a film-like peeling substrate, and has excellent production efficiency. As described above, the roll laminating roll is a roll that can be heated either or both, and the material of the roll is that the transparent conductive layer and the heat-sensitive adhesive layer are thermally bonded well, and the film base is thermally deformed. If it does not generate | occur | produce, it will not specifically limit. All combinations of metal / metal, metal / elastic, and elastic / elastic can be used as a combination of a rigid roll mainly made of metal roll and an elastic roll mainly made of heat-resistant rubber. In order to develop the tackiness of the heat-sensitive adhesive, an elastic / elastic and elastic / metal roll pair having a wide nip width and a long heating time is preferable.

In addition, as processing conditions at the time of bonding, temperature and pressure conditions for expressing the adhesiveness of the heat-sensitive adhesive to the transparent conductive layer without causing thermal deformation of the film substrate may be appropriately selected. For example, the treatment temperature is preferably 70 ° C to 150 ° C, more preferably 80 ° C to 130 ° C, and further preferably 90 ° C to 120 ° C. The pressure may be a roll linear pressure, and a minimum linear pressure that provides a good transfer state in a range of 10 kN / m to 60 kN / m may be selected.
Further, if necessary, the heat-sensitive adhesive layer portion may be preheated before bonding. Moreover, when air bubbles are mixed in the heat-sensitive adhesive layer, peeling of the conductive layer by the peeling substrate tends to be incomplete due to partial adhesion failure with the conductive layer. For this reason, in order to prevent bubbles from being mixed, the heat-sensitive adhesive layer portion of the release substrate may be heated and pressurized in a reduced pressure atmosphere in the bonding step.

  In the process of peeling the bonded film substrate and release substrate, the peeling substrate comprising the bonded film substrate with a transparent conductive layer and a support having a patterned heat-sensitive adhesive layer is cooled to about room temperature. Then, the support is peeled from the film substrate. As shown in FIG. 4, the transparent conductive layer (8) bonded to the heat-sensitive adhesive layer in the peeling step corresponds to the portion where the heat-sensitive adhesive layer (4) formed on the support (3) is formed. The transparent conductive layer (7) which is peeled from the film substrate together with the heat-sensitive adhesive layer (4) and does not correspond to the portion where the heat-sensitive adhesive is formed remains as a positive pattern of the transparent conductive layer on the film substrate (1). The pattern of the transparent conductive layer is completed on the film substrate. It should be noted that before the peeling substrate is peeled off, cooling means such as blowing cooling air to the peeling substrate support and the heat-sensitive adhesive layer portion is good for peeling and generating an unpeeled portion, etc. This is effective for preventing patterning defects.

  In the method for forming a patterned transparent conductive layer of the present invention, a negative pattern is formed with a heat-sensitive adhesive on a peeling substrate, and unnecessary portions are peeled off from the transparent conductive layer uniformly formed on the film substrate. The patterning of the transparent conductive layer by the peeling substrate is determined only by the presence or absence of the heat-sensitive adhesive applied on the support of the peeling substrate, and the pattern of the peeling substrate corresponding to the unpeeled portion of the transparent conductive layer is determined. No heat sensitive adhesive is applied to the part. Therefore, the transparent conductive layer can be reliably left on the substrate, and there is no fear that unnecessary heat-sensitive adhesive remains on the transparent conductive layer and the light transmittance of the transparent conductive layer is lowered. After the patterned transparent conductive layer is formed on the film substrate in this way, the above-described protective layer coating is applied to the film substrate partially covered with the transparent conductive layer, and the transparent conductive layer is fixed. Thus, a transparent conductive film in which the conductive layer is patterned can be manufactured.

[Heating process]
The transparent conductive film of the present invention can be formed by including a heating step after forming a transparent conductive layer mainly composed of metal nanowires on a film substrate or after laminating a transparent protective layer. A heating process here is an annealing process performed after forming a transparent protective layer, a drying process after the extraction wiring printing required when using it as a touch panel, etc.
Although the temperature range of a heating process is 100 to 200 degreeC normally and residence time 1 minute-60 minutes, it is not limited to this range.

[Touch panel]
The touch panel of the present invention is a transparent conductive film laminate formed by laminating a transparent conductive film in which a protective layer containing gallic acid or propyl gallate is laminated on a conductive layer containing metal nanowires with a double-sided adhesive sheet. It is characterized by having.

  The configuration of the touch panel of the present invention is not particularly limited, but the configuration of the capacitive touch panel is preferable because the effect of the present invention gives better results to the characteristics.

  Said transparent conductive film laminated body is a laminated body (FIG. 10) in which the adhesive layer of a double-sided adhesive sheet is directly bonded with respect to a conductive layer, and the laminated body of at least 2 layer or more is formed. A laminate (FIG. 11) provided with a hard coat layer on the opposite surface of the conductive layer containing metal nanowires is preferred. Moreover, it can also be set as the transparent conductive film laminated body which comprised the film laminated body (FIG. 12) which has a shield function.

  The thickness of the transparent conductive film laminate is preferably 0.1 mm to 2.0 mm. Within the above range, it is easy to make the touch panel thinner.

  As a preferred configuration example of the touch panel of the present invention, a transparent conductive film laminate in which a transparent conductive film is provided on one side of a double-sided pressure-sensitive adhesive sheet is provided in two layers between a display panel (transparent panel) and an image display module. A capacitive touch panel (FIG. 13) can be exemplified. Of the two transparent conductive films with pressure-sensitive adhesive layers, at least one layer may be the transparent conductive film laminate of the present invention, and the transparent conductive film with pressure-sensitive adhesive layer on the image display module side is transparent of the present invention. The structure which is an electrically conductive film laminated body, or the structure where all the two transparent conductive films with an adhesive layer are the transparent electrically conductive film laminated body of the said invention can be used as a preferable structure.

  The protective panel of the touch panel device of the present invention is not particularly limited, and examples thereof include (meth) acrylic resin, polycarbonate resin, glass, and polyethylene terephthalate resin. Of these, a (meth) acrylic resin excellent in transparency and lightness is preferable.

  The display panel of the touch panel device of the present invention may have a decorative portion. Specific examples of the decorative part include characters and figures visually recognized around the image display part of the portable electronic terminal, or a black or white background provided on the back face thereof. These decorative portions are preferably provided in order to impart designability to the portable electronic terminal.

  The thickness of the touch panel device excluding the image display module is preferably 0.3 mm to 3.0 mm. Within the above range, the electronic device in which the touch panel device is incorporated can be easily made thin.

  The image display module used for the touch panel device is not particularly limited, and an LCD module or an organic EL module usually used for a small electronic terminal can be used.

EXAMPLES The present invention will be described more specifically with reference to examples below, but the present invention is not limited to these examples.
[Preparation of transparent conductive film]
(Synthesis of silver nanowires)
Silver nanowires are Sun, B.M. Gates, B.B. Mayers, & Y. Xia, “Crystalline silver nanobe by soft solution processing”, Nano letters, (2002), 2 (2) 165-168, followed by a process using a polyol in the presence of polyvinyl pyrrolidone (PVP). It is a nanowire synthesized by dissolving silver sulfate and reducing it. That is, in the present invention, nanowires synthesized by the modified polyol method described in Cambrios Technologies Corporation US Provisional Application No. 60 / 815,627 were used.

(Preparation of transparent conductive layer)
<Conductive layer (1)>
As a metal nanowire forming a transparent conductive layer, an aqueous dispersion containing 0.5% w / v of a silver nanowire having a short axis diameter of about 70 nm to 80 nm and an aspect ratio of 100 or more synthesized by the above method in an aqueous medium Using a slot die coater (Cambrios Technologies Corporation, ClearOhmTM, Ink-A) and a 125 μm thick transparent PET film (HF1C22-125; single-sided easy contact, rear hard coat) on the easy-contact surface After applying to a wet thickness of about 20 μm and drying, a pressure treatment was performed at a pressure of 2000 kN / m ² to form a uniform transparent conductive layer (1).

<Conductive layer (2)>
The conductive layer (1) was prepared in the same manner as the conductive layer (1) except that 0.5 part of perfluorobutanesulfonic acid was added to 1 part of the solid content of the aqueous dispersion having silver nanowires. Thus, a transparent conductive layer (2) was obtained.

<Conductive layer (3)>
The conductive layer (1) was prepared in the same manner as the conductive layer (1) except that 0.2 part of gallic acid was added to 1 part of the solid content of the aqueous dispersion having silver nanowires. Layer (3) was designated.

<Conductive layer (4)>
In the conductive layer (1), except that 0.2 part of perfluorobutanesulfonic acid and 0.2 part of gallic acid were added to 1 part of the solid content of the aqueous dispersion having silver nanowires, the conductive layer A transparent conductive layer (4) was prepared in the same manner as (1).

<Conductive layer (5)>
A predetermined pattern was formed by the following pattern forming method using the conductive layer (2) to obtain a transparent conductive layer (5).

[Preparation of a substrate for peeling comprising a support having a negative patterned heat-sensitive adhesive layer]
100 parts of CRISVON NT-810-45 (a polyurethane resin manufactured by DIC, 45% solution) was dissolved in 62 parts of methyl ethyl ketone and 63 parts of toluene to obtain a heat-sensitive adhesive. Pattern printing is performed on a PET film having a thickness of 23 μm (Teijin Tetron Film G2 manufactured by Teijin DuPont Films) as a support. Here, as a desired conductive layer pattern to be formed on the substrate, the electrode pattern for the capacitive projection type touch panel of FIGS. 6 and 7 was used. The pattern is a linear pattern in which a diamond-shaped electrostatic element pattern having a side length of 4 mm and an inner angle of 90 degrees and a thin line pattern having a line width of 350 μm are alternately arranged. Therefore, on the support, the negative patterns of FIG. 8 and FIG. 9 were printed by the gravure printing method with respect to the pattern FIGS. 6 and 7 to be formed by the transparent conductive layer. After drying the printed coating, it is applied so that the thickness of the heat-sensitive adhesive layer is 0.5 μm to 0.8 μm, and the heat-sensitive adhesive is patterned and printed in a negative image as shown in FIGS. A substrate was obtained (FIG. 2).

[Patterning process of transparent conductive layer]
Next, the substrate on which the transparent conductive layer is formed and the peeling substrate having a negative patterned heat-sensitive adhesive layer are stacked so that the transparent conductive layer and the heat-sensitive adhesive layer face each other, a metal heating roll, Using a laminator with heating and heat-resistant silicon roll and a pressure nip, bonding was performed under conditions of a heating roll temperature of 110 ° C., a roll nip pressure (linear pressure) of 30 kN / m, and a speed of 5 m / min (FIG. 3). . While the bonded material is running, when the temperature of the bonded portion is lowered to about room temperature, the support is peeled off from the substrate, and the transparent conductive layer remains on the substrate in the desired pattern shape of FIGS. A patterned transparent conductive film substrate was obtained (FIG. 4).
When the patterned transparent conductive layer portion was observed with a microscope, the transparent conductive layer portion on the substrate was not damaged in the peeling step using the peeling substrate, and the transparent conductive layer was removed from the peeling substrate. The transparent conductive layer hardly remained in the peeled portion, and the heat-sensitive adhesive did not adhere.

[Preparation of protective layer]
Using the transparent conductive layers (1) to (5), the following protective layer coating was applied on the conductive layer to form a protective layer.

<Coating for protective layer (A)>
As a protective layer coating, 15 parts of acrylic acrylate, 15 parts of dipentaerythritol hexaacrylate, 1.5 parts of initiator (Irgacure 2959), 100 parts of methyl ethyl ketone, 25 parts of methyl isopropyl ketone, 25 parts of diacetone alcohol, 20 parts of gallic acid Was dissolved well to obtain a protective layer coating material (A).

<Coating for protective layer (B)>
A protective layer coating material (B) was prepared in the same manner as the protective layer coating material (A) except that the amount of gallic acid added was 4 parts in the protective layer coating material (A).

<Coating for protective layer (C)>
The protective layer coating material (A) was prepared in the same manner as the protective layer coating material (A) except that the amount of gallic acid added was 2 parts.

<Coating for protective layer (D)>
A protective layer coating (D) was prepared in the same manner as the protective layer coating (A) except that the protective layer coating (A) was replaced with gallic acid instead of gallic acid.

<Coating for protective layer (E)>
The protective layer paint (A) was prepared in the same manner as the protective layer paint (A) except that gallic acid was not added.

<Coating for protective layer (F)>
The protective layer coating material (A) was prepared in the same manner as the protective layer coating material (A) except that perfluorobutanesulfonic acid was used instead of gallic acid.

<Coating for protective layer (G)>
The protective layer coating material (A) was prepared in the same manner as the protective layer coating material (A) except that benzotriazole was used instead of gallic acid.

  This protective layer coating is applied to the transparent conductive layer on the surface of the film having the transparent conductive layer using a slot die coater, dried, and UV cured with the protective layer coating. A protective layer coating having an average coating thickness of about 0.1 μm was formed.

(Examples 1-12)
A protective layer was formed on the conductive layers (1) to (5) in the combinations shown in Table 1 using the protective layer paints (A) to (D).

(Comparative Examples 1-12)
A protective layer was formed on the conductive layers (1) to (5) in the combinations shown in Table 1 using the protective layer coatings (E) to (G).

  In addition, the aging in a table | surface was performed on the conditions which heat the transparent conductive film after protective layer formation for 30 minutes at 135 degreeC.

(Initial electrical characteristics)
A transparent conductive film not formed with a pattern is obtained by measuring the surface resistance using a sheet resistance measuring device (RC2175, manufactured by EDTM) on the coating surface of the conductive layer on which the protective layer is formed, and the measured value is obtained stably. The case was evaluated as ◯, the case where the value varied without being stable, and the case where the value exceeded the measurement limit was indicated as x.

The pattern-formed transparent conductive film measures the conduction resistance of the pattern using a tester on the coating surface of the conductive layer on which the protective layer is formed for each pattern of the transparent conductive film. ◯ when the measured value can be obtained stably, △ when the value is not stable in the transparent conductive film of at least one pattern, △, the value exceeds the measurement limit in the transparent conductive film of at least one pattern When it is, it was set as x.
The evaluation results are shown in Table 1 as initial resistance.

(Reliability evaluation of transparent conductive film)
In each transparent conductive film, reliability evaluation was performed using the increase rate of the electrical resistance value of the conductive film layer represented by the following formula. The evaluation results were as follows: the rate of increase after standing for 500 hours at 85 ° C. and 85% RH is less than 20%, ◯ is less than 30%, x is 30% to less than 50%, and xx is 50% or more. The electrical resistance value was measured in the same manner as the initial electrical characteristics.
The evaluation results are shown in Table 1 as reliability.
Rate of increase in electric resistance value of conductive film layer (%) = [(electric resistance value after standing at 85 ° C., 85% RH for 500 hours) − (initial electric resistance value)] / (initial electric resistance value) × 100

  As mentioned above, it turns out that the transparent conductive film of this invention shown in Examples 1-12 is a material suitable as a functional member regardless of the presence or absence of an aging process in the result of initial stage resistance and reliability. On the other hand, the transparent conductive films shown in Comparative Examples 1 to 12 have a characteristic that the initial resistance has no problem regardless of the presence or absence of aging. However, as a result of reliability evaluation, practical characteristics could not be obtained even when there was no aging process, and when the aging process was performed, the characteristics were remarkably inferior. Even when an antioxidant was added to the conductive layer, the reliability could not be satisfied unless gallic acid or propyl gallate was added to the protective layer.

  As is clear from the above results, even with a transparent conductive film in which characteristics that are not inferior in initial characteristics are obtained, the deterioration of the characteristics over time appears significantly by performing reliability evaluation. In particular, when the aging process is performed, the above characteristic deterioration becomes remarkable, and in order to achieve these problems, the transparent conductive film of the present invention can be used.

(Production of touch panel)
For example, in order to produce a capacitive touch panel using the transparent conductive film having the two types of transparent conductive layer patterns for touch panels of FIGS. 6 and 7 produced in Example 12, two types of patterned transparent conductive films are used. The transparent conductive layer can be directed in the same direction (for example, upward) and alternately through a step of overlapping with a spacer so that one transparent conductive layer forming portion overlaps the other conductive layer peeling portion. .
For example, a double-sided pressure-sensitive adhesive sheet is laminated on the transparent conductive layer of one transparent conductive film, and another type of transparent conductive film is placed on the other side of the double-sided pressure-sensitive adhesive sheet so that the transparent conductive layer forming portion does not overlap. In addition, a capacitive touch panel can be manufactured using a transparent conductive layer laminate formed by arranging and bonding the transparent conductive layer so as to face the same direction with respect to the transparent substrate.

(Evaluation of touch panel)
Using the two transparent conductive films each having a different transparent conductive layer pattern obtained in Example 12, the transparent conductive layer formation portion does not overlap and the transparent conductive layer has the same direction with respect to the transparent substrate. A transparent conductive layer laminate formed by being arranged and bonded so as to face was prepared for evaluation, and reliability evaluation was performed. In the evaluation of reliability, in the two transparent conductive films of the transparent conductive layer laminate, the rate of increase in the electrical resistance value of the conductive film layer represented by the formula used in (Reliability evaluation of transparent conductive film) is 85 ° C. The touch panel was evaluated for whether it was less than 20% after standing for 500 hours under 85% RH. As a result, it was confirmed that the rate of increase in electrical resistivity was less than 20%.

DESCRIPTION OF SYMBOLS 1 Film base | substrate 2 Transparent conductive layer 3 (For heat sensitive adhesive negative pattern formation) Support body 4 Heat sensitive adhesive layer 5 Heating, pressurizing metal roller 6 Heating, heat resistant silicon rubber roller 7 Patterned transparent conductive layer 8 Heat sensitive Transparent conductive layer 9 peeled off by adhesive 9 Protective layer 10 formed on patterned transparent conductive layer Protective layer 11 formed on transparent conductive layer Protective panel 12 Double-sided pressure-sensitive adhesive sheet 13 Transparent conductive layer 14 Film substrate 15 Hard coat layer 16 Fixing tape 17 Image display module 18 Decoration layer 110, 111 Transparent conductive film 112 with adhesive layer Transparent conductive film laminate

Claims (7)

It has a transparent conductive layer mainly composed of metal nanowires and a transparent protective layer on a film substrate, and the transparent protective layer is made of a protective layer coating containing gallic acid or gallic acid propellant. Transparent conductive film. The transparent conductive film according to claim 1, wherein the transparent conductive layer containing metal nanowires as a main component is formed by applying a coating solution containing metal nanowires as a main component on a substrate. The transparent conductive film of Claim 1 or 2 with which the transparent conductive layer which has the said metal nanowire as a main component is patterned. Patterning the transparent conductive layer mainly composed of the metal nanowires forms a layer having a negative patterned adhesive region on the support, and the film substrate and the support are transparent. A step of laminating the conductive layer and the adhesive region of the layer having the adhesive region so that they are in close contact with each other, and a part of the layer having the adhesive region that is in contact with the adhesive region by peeling the support from the film base The transparent conductive layer is manufactured by a process of laminating a transparent protective layer after forming a pattern of the transparent conductive layer on the film substrate by transferring the transparent conductive layer onto the adhesive region of the layer having the adhesive region. Item 4. The transparent conductive film according to any one of Items 1 to 3. The transparent conductive film according to any one of claims 1 to 4, further comprising a heating step after forming a transparent conductive layer mainly composed of metal nanowires on the film substrate or after laminating a transparent protective layer. . The said metal nanowire is a silver nanowire, The transparent conductive film in any one of Claims 1-5. The touch panel manufactured using the transparent conductive film in any one of Claims 1-6.

Images