JP6060845B2 - Manufacturing method of conductive sheet, conductive sheet, and touch panel - Google Patents

Description

  The present disclosure relates to a method for manufacturing a conductive sheet including a polythiophene-based conductive agent and conductive particles, a conductive sheet, and a touch panel including the conductive sheet.

  The resistive touch panel converts a pressure applied to a part of the conductive sheet into an electrical signal, and detects a position where the pressure is applied on the conductive sheet. Such resistive touch panels can be used for portable devices such as game machines and electronic dictionaries because operations such as pressing and writing can be output as electrical signals.

  Among the conductive sheets provided in the resistive touch panel, a sheet that employs a conductive polymer as a conductor satisfies high flexibility. For example, the conductive sheet described in Patent Document 1 employs a coating composition containing a polythiophene-based conductive agent as a conductor. Since the conductive sheet having high flexibility is less likely to be cracked by the application of pressure, it is responsible for extending the life of the resistive touch panel.

  On the other hand, a conductive sheet using a conductive polymer is in contact with an oxide semiconductor layer such as ITO (Indium Tin Oxide), which is a different type of semiconductor, in order to detect a position where pressure is applied. At this time, the contact resistance between the conductive sheet containing the polythiophene-based conductive agent and the ITO is higher than the contact resistance between the ITO films, which increases the input load of the resistive film type touch panel.

  Therefore, the conductive sheet described in Patent Document 2 includes hydrophilic particles in the conductive layer for the purpose of suppressing such an input load, and improves the contact between the oxide semiconductor layer and the conductive layer. Moreover, the electroconductive sheet of patent document 3 to patent document 5 contains the electroconductive particle in the electroconductive layer for the purpose of suppressing input load similarly.

JP 2006-289780 A JP 2007-321131 A JP-T-2006-502254 JP 2009-037752 Special table 2011-500196 gazette

  By the way, in addition to ensuring sensitivity to pressing and writing, it is also necessary for the resistive touch panel to ensure scratch resistance that is resistance to repeated pressing and writing. The conductive sheet containing the hydrophilic particles and conductive particles described above can increase the sensitivity to pressing and writing by adding particles, but still has room for improvement from the viewpoint of enhancing the scratch resistance. In addition, the request | requirement which raises such abrasion resistance is common not only to the electrode of a resistance film type touch panel but the conductive sheet which has a conductive layer in a base material, such as an electrode of a capacitive touch panel, and an electromagnetic wave shield in a touch panel.

  An object of the technology of the present disclosure is to provide a method for producing a conductive sheet, a conductive sheet, and a touch panel, which include a polythiophene-based conductive agent and conductive particles, and have improved scratch resistance.

  In the technique of the present disclosure, one embodiment of a method for producing a conductive sheet includes a step of applying a coating liquid to a substrate to form a coating film, and a step of drying the coating film to form a conductive layer. . The coating liquid includes a polythiophene-based conductive agent, a binder, conductive particles, and a silane coupling compound, and when the mass part of the polythiophene-based conductive agent is 100, the conductive particle has 20 or more parts by mass. And the mass part of a silane coupling compound is 100 or more and 240 or less. In the conductive layer, the film thickness a of the conductive layer and the minor axis diameter b of the conductive particles satisfy the following formulas 1 and 2.

a> 100 nm Formula 1
1.5 <b / a <5 Formula 2
One aspect of the conductive sheet in the technology of the present disclosure is a conductive sheet manufactured by the above-described method for manufacturing a conductive sheet.

  In the technology of the present disclosure, one aspect of the conductive sheet includes a base material and a conductive layer provided on the base material. The conductive layer includes a polythiophene-based conductive agent, a binder, conductive particles, a silane coupling compound, and a coupling component that is a reaction product of the silane coupling compound, and the content of the conductive particles is 6 The content of silicon element is 3% by mass or more and 7% by mass or less. The film thickness a of the conductive layer and the minor axis diameter b of the conductive particles satisfy the following formulas 1 and 2.

a> 100 nm Formula 1
1.5 <b / a <5 Formula 2
In the conductive sheet in the technique of the present disclosure, the conductive particles are spherical particles dispersed in the conductive layer, and the short axis diameter b of the conductive particles and the long axis diameter c of the conductive particles are expressed by the following formula 3 It is preferable to satisfy.

c / b <2 Equation 3
In the conductive sheet in the technology of the present disclosure, the conductive particles are at least one selected from the group consisting of silver particles, copper particles, silver particles whose surfaces are treated, and copper particles whose surfaces are treated. It is preferable.

  In the technology of the present disclosure, one aspect of the touch panel includes the conductive sheet.

  The manufacturing method of the electroconductive sheet of this indication, an electroconductive sheet, and a touch panel improve abrasion resistance in the electroconductive sheet containing a polythiophene type electrically conductive agent and electroconductive particle.

It is sectional drawing which shows the cross-section of an electroconductive sheet in one Embodiment which actualized the electroconductive sheet of this indication. It is sectional drawing which shows an example of the cross-sectional structure of the electroconductive sheet which has other functional layers other than an electroconductive layer in one Embodiment which actualized the electroconductive sheet of this indication. It is sectional drawing which shows the other example of the cross-section of the electroconductive sheet which has other functional layers other than an electroconductive layer in one Embodiment which actualized the electroconductive sheet of this indication. It is sectional drawing which shows the other example of the cross-section of the electroconductive sheet which has other functional layers other than an electroconductive layer in one Embodiment which actualized the electroconductive sheet of this indication. It is a disassembled perspective view which shows the disassembled perspective structure of the resistive film type touch panel in one Embodiment which actualized the touch panel of this indication.

An embodiment embodying the technology of the present disclosure will be described with reference to FIGS. 1 to 5. First, the electroconductive sheet in this embodiment is demonstrated.
[Configuration of conductive sheet]
As shown in FIG. 1, the conductive sheet 10 includes a base material 11 and a conductive layer 12 provided on the base material 11. The conductive layer 12 includes a polythiophene-based conductive agent, a binder, conductive particles, a silane coupling compound, and a coupling component that is a reaction product of the silane coupling compound. In the conductive sheet 10, the conductive layer 12 may be formed on one side of the base material 11, or may be formed on both sides of the base material 11.

  The shape of the conductive layer 12 is appropriately selected according to the target device to which the conductive sheet 10 is applied. For example, when the conductive sheet 10 is used as an electrode of a resistive film type touch panel, the conductive layer 12 has a layer shape that extends over substantially the entire side surface of the substrate 11. Further, for example, when the conductive sheet 10 is used as an electrode of a capacitive touch panel, the conductive layer 12 has a regular pattern shape suitable for capacitance detection.

The base material 11 and the conductive layer 12 may be colorless and transparent, or may be colored and transparent. When the conductive sheet 10 is used for an electrode of a touch panel, the base material 11 and the conductive layer 12 are preferably colorless and have high transparency. The conductivity of the conductive layer 12 is not particularly limited as long as the conductivity is higher than that of the substrate 11. When the conductive sheet 10 is used for an electrode of a touch panel, the surface resistance of the conductive layer 12 is preferably 10 ⁵ Ω / sq or less, and more preferably 10 ³ Ω / sq or less.

  The conductive sheet 10 may have a configuration in which only the conductive layer 12 is provided on the base material 11, or may have a configuration in which another functional layer other than the conductive layer 12 is included in the base material 11. The functional layer other than the conductive layer 12 is, for example, at least one selected from the group consisting of an optical adjustment layer, an anchor layer, a barrier layer, and a hard coat layer. The functional layer other than the conductive layer 12 may have a single layer structure including a single layer, or may have a stacked structure in which a plurality of layers are stacked.

  The optical adjustment layer is a layer that adjusts optical characteristics with respect to visible light in the conductive sheet 10. For example, a refractive index adjustment layer that adjusts the refractive index between layers in a plurality of layers constituting the conductive sheet 10. It is. The optical adjustment layer is, for example, an anti-neutral ring layer that is a layer having a sea-island structure or a layer to which various diffusing agents are added. An anchor layer has a function which improves the adhesiveness between layers in the several layer which comprises the electroconductive sheet 10, for example, is a layer containing reactive substances, such as isocyanate. The barrier layer has a function of suppressing the gas contained in the base material 11 from separating from the base material 11. The hard coat layer is a layer that suppresses the generation of scratches and dirt on the ground covered with the hard coat layer, and is, for example, a layer made of a hard resin.

  As shown in FIG. 2, other functional layers other than the conductive layer 12 may be provided as the back surface layer 13 on the side surface of the base material 11 where the conductive layer 12 is not formed. For example, at least one selected from the group consisting of an optical adjustment layer, a barrier layer, and a hard coat layer may be provided as the back surface layer 13 on the back surface of the substrate 11. Further, if the functional layer other than the conductive layer 12 is provided on the back surface of the base material 11, an anchor layer may be provided between the functional layer and the base material 11.

  As shown in FIG. 3, the functional layer other than the conductive layer 12 may be provided as the undercoat layer 14 on the side surface of the base material 11 where the conductive layer 12 is formed. For example, at least one selected from the group consisting of an optical adjustment layer, a barrier layer, an anchor layer, and a hard coat layer may be provided as the undercoat layer 14 between the substrate 11 and the conductive layer 12.

  As shown in FIG. 4, other functional layers other than the conductive layer 12 are provided as the back layer 13 on the side surface of the base material 11 where the conductive layer 12 is not formed, and the conductive layer 12 is formed. The undercoat layer 14 may be provided on the side surface. For example, at least one selected from the group consisting of an optical adjustment layer, a barrier layer, and a hard coat layer may be provided as the back surface layer 13 on the back surface of the substrate 11. Further, if the functional layer other than the conductive layer 12 is provided on the back surface of the base material 11, an anchor layer may be provided between the functional layer and the base material 11. In addition, for example, at least one selected from the group consisting of other optical adjustment layers, other barrier layers, other anchor layers, and other hard coat layers is provided between the substrate 11 and the conductive layer 12. May be provided as an undercoat layer 14.

The transparency of the conductive sheet 10 is preferably 70% or more, more preferably 80% or more, as the total light transmittance (JIS K7105). Further, the haze (JIS K7105) of the conductive sheet 10 may be 10% or less, except for a structure that intentionally has light diffusibility, such as imparting antiglare (AG) properties to the conductive sheet 10. Preferably, it is 5% or less.
[Substrate 11]
The base material 11 includes a sheet base material formed into a sheet shape such as a glass substrate, a resin film, and a resin plate. The base material 11 may be comprised only from the sheet | seat base material, and may be comprised from the sheet | seat base material and other functional layers other than the conductive layer 12 formed in the surface as needed. .

  The surface of the base material 11 may be a flat surface or an uneven surface subjected to a shaping process such as a sandblasting process or a solvent process. The surface of the substrate 11 may be subjected to surface oxidation treatment such as corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, and ultraviolet irradiation treatment, and adhesion to the conductive layer 12 and other functional layers. Is sufficiently obtained, it is not always necessary to perform such surface oxidation treatment.

  The resin film forming material and the resin plate forming material are, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene naphthalate, polyethylene, polypropylene, cellophane, diacetylcellulose, triacetylcellulose, cycloolefin Polymer, acetylcellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyimide , Fluororesin, polyamide, (meth) acrylic resin, copolymer of methyl methacrylate and styrene At least one selected from Ranaru group.

  From the viewpoint of increasing transparency, weather resistance, solvent resistance, and cost reduction, the sheet base material is a biaxially stretched film of polyethylene terephthalate, a glass substrate, a sheet made of cycloolefin polymer or polycarbonate. Preferably there is. In particular, from the viewpoint of obtaining high flexibility, the sheet substrate is preferably a sheet made of a polyethylene terephthalate biaxially stretched film, a cycloolefin polymer, or a polycarbonate. Further, from the viewpoint of satisfying high flexibility, the thickness of the sheet base material is preferably 10 μm or more and 200 μm or less.

The sheet base material may contain various additives as long as the transparency of the sheet base material is not hindered. Additives contained in the sheet substrate include, for example, antioxidants, heat stabilizers, ultraviolet absorbers, organic particles, inorganic particles, pigments, dyes, fine fibers, antistatic agents, nucleating agents, silane coupling compounds, etc. is there.
[Polythiophene-based conductive agent]
The polythiophene-based conductive agent constituting the conductive layer 12 is a polythiophene having a π-conjugated main chain in which carbon-to-carbon double bonds and carbon-to-carbon single bonds are alternately arranged to exhibit conductivity in the main chain. System compounds. A polythiophene-based compound is a conductive agent exhibiting high transparency while exhibiting electrical conductivity while hardly exhibiting light absorption in the visible light region.

  The polythiophene compound is selected from the group consisting of a polymer of 3-hexylthiophene, a polymer of 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT) (hereinafter referred to as PEDOT), and derivatives thereof. It is preferable that it is at least one. The polythiophene compound may be composed of one type of polymer or a mixture of two or more types of polymers. The polythiophene compound is not limited to a polymer of 3-hexylthiophene and PEDOT, but may be a polythiophene derivative other than these. The kind and composition of the polythiophene compound in the polythiophene conductive agent are appropriately selected according to the use of the conductive sheet 10 and the like.

  The polymer derivative of 3-hexylthiophene is, for example, a self-doped polythiophene having a sulfonic acid group in the main chain. The derivative of PEDOT is, for example, an organic solvent dispersion type PEDOT in which a flexible polymer such as polyethylene glycol and EDOT are copolymerized.

  As a method for forming the conductive layer 12 including the polythiophene-based conductive agent, coating or printing on the base material 11 is used. The raw material used for coating and the raw material used for printing are a liquid containing a polythiophene-based conductive agent, that is, a coating liquid.

  The coating liquid for forming the conductive layer preferably contains a dopant that increases the conductivity of the conductive layer 12 and a dispersion medium that increases the dispersibility of the polythiophene compound. Polystyrene sulfonic acid (hereinafter referred to as PSS) and polyvinyl sulfonic acid (hereinafter referred to as PVS) have a function as a dispersion medium that disperses PEDOT in water in water in addition to the function as a dopant. In the conductive layer forming coating liquid and the conductive layer 12 formed from the conductive layer forming coating liquid, the polythiophene-based conductive agent may include a polythiophene-based compound and a dopant that increases the conductivity thereof.

  The coating liquid containing PEDOT may further contain a high-boiling solvent that increases the conductivity of the conductive layer 12 as a secondary dopant. If the secondary dopant is included in the conductive layer 12, the conductivity of the conductive layer 12 is further increased. The secondary dopant is, for example, at least one selected from the group consisting of polyethylene glycol, methylformamide, dimethyl sulfoxide, and N-methylpyrrolidone. The blending amount of the secondary dopant in the coating liquid for forming the conductive layer is preferably 1% by mass or more and 10% by mass or less, and preferably 2% by mass or more, with respect to the coating liquid for forming the conductive layer. 8 mass% or less is more preferable. In the configuration in which the addition amount of the secondary dopant is lower than 1% by mass, the effect as the secondary dopant cannot be sufficiently obtained. Moreover, in the structure where the addition amount of the secondary dopant is higher than 10% by mass, the amount of the secondary dopant which is a high boiling point solvent becomes excessive in the conductive layer 12, and the secondary dopant may bleed (elution). is there.

  For adjusting the coating liquid containing PEDOT, for example, a method of polymerizing EDOT in the presence of PSS to obtain PEDOT-PSS as an aqueous dispersion is suitable. Also suitable is a method of polymerizing EDOT in the presence of PVS to obtain PEDOT-PVS as an aqueous dispersion. In particular, the method of obtaining PEDOT-PSS is more preferable in that high conductivity can be obtained.

From the viewpoint of increasing the conductivity of the conductive layer 12, the blending amount of the polythiophene-based conductive agent in the conductive layer 12 is preferably as high as possible. The blending amount of the polythiophene-based conductive agent in the conductive layer 12 is 10 mass relative to the mass component of the conductive layer 12 from the viewpoint of increasing the conductivity of the conductive layer 12 and increasing the ease of coating of the conductive layer 12. % Or more and 90% by mass or less, more preferably 30% by mass or more and 70% by mass or less.
[binder]
The binder constituting the conductive layer 12 is a resin that fixes the state of the polythiophene-based conductive agent at the conductive layer 12. From the viewpoint of increasing the conductivity of the conductive layer 12, the blending amount of the polythiophene-based conductive agent in the conductive layer 12 is preferably as high as possible. On the other hand, the higher the blending amount of the polythiophene-based conductive agent in the conductive layer 12, the higher the degree of decrease in conductivity due to various stresses such as temperature, humidity, solvent, and abrasion. The binder fixes the state of the polythiophene-based conductive agent in the conductive layer 12 and suppresses the decrease in conductivity due to such various stresses.

  The binder is, for example, at least one selected from the group consisting of acrylic resin, styrene resin, polyester resin, alkyd resin, urethane resin, amide resin, modified resins thereof, and copolymer resins thereof. The binder may be one type of resin or a mixture of two or more types of resins different from each other. The binder is appropriately selected depending on the configuration of the polythiophene-based conductive agent and the configuration of the substrate 11. From the viewpoint of obtaining low hygroscopicity, high acid resistance, and excellent coating suitability, the binder is preferably a polyester resin.

  The binder may include a monomer or oligomer as a raw material thereof, and may further include a polymerization initiator, a crosslinking agent, and the like. The coating liquid for forming the conductive layer 12 contains at least a monomer or an oligomer as a raw material for the binder, and contains a polymerization initiator.

  The raw material of the binder is, for example, polyester (meth) acrylate, urethane (meth) acrylate, or epoxy (meth) acrylate. Hereinafter, monofunctional means that it has one polymerizable unsaturated group, bifunctional means that it has two polymerizable unsaturated groups, and trifunctional means that it has three polymerizable unsaturated groups. Indicates.

  When the binder is a radical polymer, the raw material of the binder is monofunctional, for example, ethyl carbitol (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, nonylphenol ethylene oxide modified (meth) acrylate, ethoxydiethylene glycol acrylate, It is at least one selected from the group consisting of acryloylmorpholine, isobornyl (meth) acrylate, and N-vinylpyrrolidone.

  When the binder is a radical polymer, the raw material of the binder is bifunctional, for example, hexanediol di (meth) acrylate, hexanediol ethylene oxide modified diacrylate, neopentyl glycol polyethylene oxide modified di (meth) acrylate, tetraethylene Selected from the group consisting of glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate, polyethylene glycol di (meth) acrylate At least one.

  When the binder is a radical polymer, the material of the binder is trifunctional or higher, for example, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin propoxy sheetary (meth) acrylate , Dipentaerythritol hexaacrylate, and ditrimethylolpropane tetraacrylate.

  When the binder is a cationic polymer, the raw material of the binder is, for example, at least one selected from the group consisting of epoxy compounds such as glycidyl ether compounds and alicyclic epoxy compounds, oxetane compounds, and vinyl ether compounds. It is not limited to.

The polymerization initiator is, for example, an azo compound such as azobisisobutyronitrile, an organic peroxide such as benzoyl peroxide, or a dihalogen compound, and other known ones may be used. From the viewpoint of increasing the conductivity of the polythiophene-based conductive agent, the blending amount of the binder in the conductive layer 12 is preferably small. In addition, when the compounding quantity of a binder is too small, the suitability with respect to coating of a coating liquid will become low. From these viewpoints, when the polythiophene-based conductive agent is 100 parts by mass, the blending amount of the binder is preferably 500 parts by mass or less, and more preferably 300 parts by mass or less. Moreover, 10 mass parts or more are preferable and, as for the compounding quantity of a binder, 20 mass parts or more are more preferable.
[Conductive particles]
The shape and size of the conductive particles constituting the conductive layer 12 are in a range satisfying the following formulas 1 and 2 in the film thickness a of the conductive layer 12 and the minor axis diameter b of the conductive particles. In particular, it is not limited. The shape of the conductive particles may be a spherical shape, a flat plate shape, a flake shape, a linear shape, or an indefinite shape. Furthermore, from the viewpoint of little influence on the external appearance of the conductive layer 12 and improved scratch resistance, the shape of the conductive particles is as follows for the short axis diameter b of the conductive particles and the long axis diameter c of the conductive particles. It is preferable to satisfy Formula 3, a spherical shape having a shape with less unevenness on the particle surface is more preferable, and a true spherical shape is more preferable.

a> 100 nm Formula 1
1.5 <b / a <5 Formula 2
c / b <2 Equation 3
When b / a is smaller than 1.5, in the process of forming the conductive layer 12, the conductive particles are likely to aggregate, and there is a high possibility that the conductive particles are buried deep from the surface of the conductive layer 12. . On the other hand, when b / a is larger than 5, the conductive particles easily fall off from the conductive layer 12, and it is difficult to obtain the effect of the addition of the conductive particles.

  The film thickness a of the conductive layer is an average value of film thicknesses obtained from different portions in the conductive layer 12, and is obtained from an observation image such as a scanning electron microscope or an optical microscope. The film thickness “a” of the conductive layer is, for example, an average value obtained from the film thicknesses of 20 different places in the conductive layer 12. The minor axis diameter b of the conductive particles is an average value of primary particle diameters in the minor axis direction obtained from each of the plurality of conductive particles, and the surface observation image of the conductive layer 12 and the cross-sectional observation image of the conductive layer 12 are obtained. Obtained from. The short axis diameter b of the conductive particles is obtained by, for example, obtaining the short axis diameters of 100 different conductive particles in the portion used for calculating the film thickness a of the conductive layer, and the average value of the short axis diameters. As required.

  When the conductive sheet 10 is used as an electrode of a resistive film type touch panel, the unevenness of the surface shape of the conductive particles can scratch the surface of the counter electrode facing the conductive layer 12. The conductive particles having a spherical shape and the conductive particles having a true spherical shape suppress such a possibility. The conductive particles having a linear shape may increase the variation in conductivity in the conductive layer 12, but the conductive particles having a spherical shape and the conductive particles having a true spherical shape also suppress such a possibility. .

  The material for forming the conductive particles is not particularly limited within the range of the material exhibiting conductivity. The material for forming the conductive particles is made of, for example, a metal such as gold, silver, or copper, a metal oxide such as ITO or ATO, a metal compound other than the metal oxide, an organic conductive polymer such as polyaniline or polypyrrole, or carbon. It is at least one selected from the group. From the viewpoint of increasing conductivity, scratch resistance, and corrosion resistance, the material for forming the conductive particles is preferably a metal such as gold, silver, or copper.

  One conductive particle may be formed from one type of forming material, or may be formed from two or more types of forming materials different from each other. One conductive particle may be, for example, a silver-coated copper particle in which the surface of the copper particle is covered with silver. Further, the conductive particles may be particles that have been subjected to a surface treatment other than coating in order to improve oxidation resistance and corrosion resistance. Silver is preferable as a surface material from the viewpoint of increasing conductivity, scratch resistance, and corrosion resistance, and copper is preferable as a bulk material from the viewpoint of reducing the cost of the forming material.

  The conductive particles contained in the conductive layer 12 may be one type of conductive particles, or may be a mixture of two or more types of conductive particles formed from different forming materials. The conductive particles contained in the conductive layer 12 may be, for example, a mixture of silver-coated copper particles and silver particles, or a mixture of silver-coated copper particles and copper particles.

  The distribution of the conductive particles contained in the conductive layer 12 may be configured such that the conductive particles are biased to a specific portion where the conductive layer 12 and another conductive member are in contact with each other, or the entire conductive layer 12 is conductive. The particles may be configured to be uniformly dispersed, or the conductive particles may be configured to be uniformly dispersed over the entire surface of the conductive layer 12. When the conductive layer 12 containing conductive particles comes into contact with another conductive member facing the conductive layer 12, a part of the surface of the conductive layer 12 rubs against the surface of the other conductive member. If the conductive particles are dispersed throughout the surface of the conductive layer 12, the conductive particles and other conductive members are in point contact, and the conduction between the conductive layer 12 and the other conductive members during the above-described rubbing is particularly Stabilize. If the conductive particles satisfy the above formulas 1 and 2, the protection of the conductive layer 12 and the stability of conduction are enhanced, and the conductive particles are uniformly dispersed on the surface of the conductive layer 12. If it is a structure, the effect is remarkable.

  Typical methods for producing silver particles suitable as the conductive particles are, for example, an atomizing method and a wet reduction method. The wet reduction method is preferable from the viewpoints of easily obtaining spherical conductive particles and easily dispersing the conductive particles uniformly. Silver particles suitable as the conductive particles are exemplified in Japanese Patent Application Laid-Open No. 2004-100013, Japanese Patent Application Laid-Open No. 2005-093380, and the like, and described in Japanese Patent Application Laid-Open No. 11-189812. It is also possible to include other metal components as long as they are not greatly reduced.

  In order to suppress excessive aggregation of the conductive particles, a protective colloid that protects the conductive particles may be used in the production of the conductive particles, or a stabilizer that stabilizes the dispersed state of the conductive particles. May be used. As the protective colloid and stabilizer, carboxylic acid compounds such as gelatin, gum arabic, polyvinyl alcohol, ascorbic acid, amine compounds, thiol compounds, and the like are used. In addition, when the polythiophene-based conductive agent coexists, the amine compound and the thiol compound are strongly bonded to the surface of the silver particle, and an insulating coating layer is formed on the surface of the silver particle, Since it is easy to cause aggregation, it is preferably used as a combination of conductive particles other than silver particles and conductive particles other than particles having silver on the surface.

  The conductive particles contained in the conductive layer 12 form not only irregularities on the surface of the conductive layer 12, so if the amount of the conductive particles is excessive, optical characteristics such as transmittance required for the conductive layer 12. Excessive conductive particles are lowered. The range of the blending amount of the conductive particles in which the surface protection of the conductive layer 12 and the stability of conduction are enhanced by the conductive particles and the optical properties required for the conductive layer 12 are maintained are as follows (a ) And (b). That is, the range of the blending amount of the conductive particles that enhances the sensitivity to pressing and writing and the resistance to repeated pressing and writing is at least one of the following (a) and (b).

(A) In the coating liquid, when the mass part of the polythiophene-based conductive agent is 100, the mass part of the conductive particles is 20 or more and 100 or less.
(B) In the conductive layer 12, the content rate which is the mass of the electroconductive particle with respect to the mass of the conductive layer 12 is 6 mass% or more and 25 mass% or less.
[Coupling ingredients]
The coupling component constituting the conductive layer 12 is composed of a silane coupling compound and a reaction product of the silane coupling compound. The reactant of the silane coupling compound is a product obtained by dehydration condensation of the silane coupling compound. The coupling component has a function of crosslinking the binders. The coupling component enhances the ease of application of the conductive layer 12 and the hardness of the conductive layer 12 by crosslinking, and also enhances the adhesion between the conductive layer 12 and the base thereof by crosslinking.

  For example, when the conductive layer 12 is formed on the base material 11 containing a large amount of silicon component or the base material 11 having a hard coat layer containing silicon component on the surface, the coupling component is formed between the conductive layer 12 and its underlying layer. Increase adhesion between. In particular, when a PET film is used as the substrate 11, an adhesive layer containing a silicon component is formed on the surface of the PET film, and the conductive layer 12 is formed on the adhesive layer, the coupling component is The adhesion between the substrate 11 is increased.

  The silane coupling compound is, for example, at least one selected from the group consisting of epoxy-based, vinyl-based, methacrylic-based, acrylic-based, and sulfide-based, and among these, the adhesion between the conductive layer 12 and the base thereof. From the viewpoint of increasing the viscosity, an epoxy-based silane coupling compound is preferable.

  From the viewpoint of increasing the conductivity by the polythiophene-based conductive agent, the amount of the coupling component contained in the conductive layer 12 is preferably as small as possible. On the other hand, when the blending amount of the coupling component is too small, the ease of application of the conductive layer 12 and the hardness of the conductive layer 12 are reduced, and the adhesion between the conductive layer 12 and the base thereof is also reduced. descend. A cup that improves the ease of application of the conductive layer 12, the protective property of the conductive layer 12, and the adhesion between the conductive layer 12 and the base thereof, and the conductivity required for the conductive layer 12. The range of the ring component is at least one of the following (c) and (d). That is, the range of the amount of the coupling component that increases the sensitivity to pressing and writing and the resistance to repeated pressing and writing is at least one of the following (c) and (d).

(C) In a coating liquid, when the mass part of a polythiophene type | system | group electrically conductive agent is 100, the mass part of a silane coupling compound is 100 or more and 240 or less.
(D) In the conductive layer 12, the content rate of the silicon element with respect to the mass of the conductive layer 12 is 3 mass% or more and 7 mass% or less.

In addition, a coupling compound other than the silane coupling compound may be added to the coating solution for forming the conductive layer 12 within a range that does not impair the effects of the present invention.
[Additive]
The coating liquid for forming the conductive layer for forming the conductive layer 12 is added within a range that does not significantly reduce the conductivity, in addition to the polythiophene-based conductive agent, binder, conductive particles, and coupling component. Agents may be included. The conductive layer 12 formed from the coating liquid for forming the conductive layer may also contain such an additive.

  Additives include additives such as antioxidants, heat stabilizers, UV absorbers, metal corrosion inhibitors, pH adjusters, organic particles, inorganic particles, pigments, dyes, fine fibers, antistatic agents, nucleating agents, and the like , At least one selected from the group consisting of coating aids such as wetting agents and antifoaming agents.

  The coating aid has a function of suppressing the occurrence of defects such as holes in the conductive layer 12. Examples of the coating aid include silicone-based, long-chain alkyl-based, and fluorine-based surfactants. From the viewpoint of improving the adhesion between the conductive layer 12 and the base material 11, the coating aid is added in an amount of 50 ° or more and 100 ° or less, more preferably 60 ° or less, as the contact angle of the coating liquid to the base. A configuration in which the angle is set to be equal to or larger than 90 ° and equal to or smaller than 90 ° is preferable. The surface active function of the coating aid may be possessed by a binder or a silane coupling compound.

The pH adjuster has a function of suppressing deterioration of the polythiophene-based conductive agent due to pH fluctuation. For example, when the polythiophene-based conductive agent is PEDOT-PSS, the oxidation reaction of PEDOT and the hydrolysis reaction of PSS can be suppressed by adding a pH adjusting agent. The pH adjuster is, for example, at least one selected from the group consisting of an acetic acid-sodium acetate mixture, a phosphoric acid-sodium phosphate mixture, a citric acid-sodium citrate mixture, and a glycine-hydrochloric acid mixture.
[Method for Producing Conductive Sheet 10]
In the method for manufacturing the conductive sheet 10, first, coating or printing using a coating liquid for forming a conductive layer is performed on the side surface of the base material 11 on which the conductive layer 12 is to be formed. Is applied to form a coating film. Next, the conductive layer 12 is formed by curing the coating film formed on the substrate 11.

  Since the conductivity of the polythiophene-based conductive agent is high under acidic conditions, the pH of the coating liquid for forming the conductive layer is preferably 1 or more and 6 or less. When the pH of the coating solution is high, for example, an acidic solution such as sulfuric acid or hydrochloric acid may be added to the coating solution, or a pH adjuster may be added to the coating solution.

  Examples of the coating method include a method using a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and the like. When there is little coating liquid used for coating, it is preferable to use a micro gravure coater. Examples of the printing method include screen printing, offset printing, flexographic printing, gravure offset printing, and inkjet printing.

  Examples of the curing method of the coating film include drying of the coating film by a heated air dryer or a vacuum dryer. When the binder contained in the coating liquid is a thermosetting resin, the coating film may be heated using a heating furnace or an infrared lamp when the coating film is cured. In addition, when the binder contained in the coating liquid is an active energy ray-curable resin, the coating film may be irradiated with active energy rays when the coating film is cured.

  The active energy rays are, for example, ultraviolet rays or electron beams, and are preferably ultraviolet rays from the viewpoint of high versatility. As the ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like is used. As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as a Cockloftwald type, a bandecraft type, a resonant transformation type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type is used. Curing by irradiation with active energy rays is preferably performed in the presence of an inert gas such as nitrogen in order to avoid curing inhibition by oxygen in the atmosphere, and nitrogen gas can be suitably used from the viewpoint of cost. In addition, the active energy ray irradiation process may be performed in two stages, a preliminary curing process and a main curing process.

  Even in the configuration in which other functional layers other than the conductive layer 12 are provided, the formation of the other functional layers is performed by, for example, coating using a coating liquid for the functional layer or printing. A functional layer other than the conductive layer 12 is formed by curing the formed coating film.

The patterning on the conductive layer 12 may be a method of forming a coating film only on the surface of the substrate 11 where the conductive layer 12 is to be formed, or the conductive layer formed on the surface of the substrate 11. 12 may be a method in which etching is further performed. For example, a gravure coater or various types of printing is used as a method of forming a coating film only at a portion where the conductive layer 12 is to be formed. For the etching of the conductive layer 12, for example, wet etching or dry etching including ablation by laser light is used.
[Touch panel]
The touch panel including the conductive sheet 10 may be a resistance film type touch panel using the conductive layer 12 as an electrode, or may be a resistance film type touch panel using the conductive layer 12 as a shield layer. The touch panel provided with the conductive sheet 10 may be a capacitive touch panel using the conductive layer 12 as an electrode, or may be a capacitive touch panel using the conductive layer 12 as a shield layer. The electrode carried by the conductive layer 12 may be the upper electrode of the touch panel, the lower electrode of the touch panel, or both the upper electrode and the lower electrode.

  In addition, in the touch panel which has electrodes other than the conductive layer 12, the electrodes other than the conductive layer 12 may be a metal oxide compound layer such as ITO or ATO, or silver or copper having a mesh shape. The metal layer may be an electrode formed by coating a nanowire material. Moreover, electrodes other than the conductive layer 12 may be comprised from carbon-type compounds, such as carbon nanowire which has electroconductivity, and a graphene.

Hereinafter, an example in which the conductive layer 12 is used for the upper electrode of a resistive touch panel that is an example of a touch panel will be described.
As shown in FIG. 5, the resistive touch panel 20 is a laminated body of the conductive sheet 10 and the ITO glass 21. The conductive layer 12 of the conductive sheet 10 faces the ITO glass 21, and a dot spacer (not shown) is arranged between the conductive layer 12 and the ITO glass 21 so as to leave a predetermined gap. The conductive layer 12 of the conductive sheet 10 functions as an upper electrode of the resistive film type touch panel 20, and the ITO glass 21 functions as a lower electrode of the resistive film type touch panel 20.

  The side surface facing the ITO glass 21 in the conductive layer 12 has two conductive layer extraction electrodes P1 facing each other. The two conductive layer extraction electrodes P <b> 1 have a linear shape along one side constituting the edge of the conductive layer 12. One extraction electrode P <b> 1 is formed in the vicinity of one side that forms the edge of the conductive layer 12, and the other extraction electrode P <b> 1 is formed in the vicinity of the other side that forms the edge of the conductive layer 12. The two conductive layer extraction electrodes P1 are covered with an insulating adhesive G1 so that the extraction electrode P1 and the ITO glass 21 do not directly contact each other. The lead electrodes P1 for the two conductive layers are separately connected to an external detection circuit through an anisotropic conductive adhesive or anisotropic conductive paste. The material for forming the extraction electrode P <b> 1 is not particularly limited as long as it is in a state where more stable conduction than the conductive layer 12 can be ensured. The extraction electrode P1 is, for example, silver, copper, aluminum, molybdenum, etc., which are highly conductive metals.

  The side surface of the ITO glass 21 that faces the conductive layer 12 has two lead electrodes P2 for ITO glass that face each other. The two lead electrodes P <b> 2 for ITO glass have a linear shape along one side constituting the edge of the ITO glass 21. One extraction electrode P <b> 2 is formed in the vicinity of one side constituting the edge of the ITO glass 21, and the other extraction electrode P <b> 2 is formed in the vicinity of the other side constituting the edge of the ITO glass 21. The two extraction electrodes P2 for ITO glass are located along the direction orthogonal to the extraction electrode P1 for the conductive layer. The two extraction electrodes P2 for ITO glass are covered with an insulating adhesive G2 so that the extraction electrode P2 and the conductive layer 12 do not directly contact each other. The two lead electrodes P2 for ITO glass are separately connected to an external detection circuit through an anisotropic conductive adhesive or anisotropic conductive paste. The material for forming the extraction electrode P2 is not particularly limited as long as it is in a state where more stable conduction than the ITO glass 21 can be secured. The extraction electrode P2 is, for example, silver, copper, aluminum, molybdenum, etc., which are highly conductive metals.

  The distance between the conductive layer 12 and the ITO glass 21 is adjusted by the thickness of the adhesive materials G1 and G2. The adhesive materials G1 and G2 may be composed of an adhesive layer, or may be composed of adhesive layers on both surfaces of the base material of the adhesive materials G1 and G2. The forming materials of the adhesive materials G1 and G2 are, for example, natural rubber-based adhesives, synthetic rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, silicone-based adhesives, etc., solvent-based, emulsion-based, water-based, etc. Either may be sufficient. Of these, solvent-based acrylic pressure-sensitive adhesives are particularly preferred from the viewpoints of increasing transparency, weather resistance, durability, and cost reduction. Furthermore, from the viewpoint of obtaining high adhesiveness, the forming material of the adhesive materials G1 and G2 is particularly preferably a polymer containing ethylhexyl acrylate or butyl acrylate as a monomer unit. Moreover, an auxiliary agent may be added to the pressure-sensitive adhesive as necessary. Examples of auxiliary agents include ultraviolet absorbers, thickeners, pH adjusters, tackifiers, binder components, coupling components, adhesive particles, antifoaming agents, antiseptic / antifungal agents, and the like.

The manufacturing method of the electroconductive sheet in this indication, the electroconductive sheet, and the example which is an example of a touch panel are described below. In addition, "%" shown in an Example shows the mass% unless there is particular notice.
[Example 1]
[Preparation of conductive sheet]
As the substrate 11, a biaxially stretched polyethylene terephthalate film (trade name: Lumirror U48, manufactured by Toray Industries, Inc., thickness 188 μm) having easy-adhesion layers on both sides was used. On one side of the biaxially stretched polyethylene terephthalate film, a hard coat agent (trade name: Murasaki UV-7600B, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied with a bar coater so that the film thickness after drying was 5 μm. Thereafter, the coating film was dried with hot air at 80 ° C. Next, a hard coat layer for the back surface was formed by irradiating the coating film with 300 mJ / cm ² of ultraviolet light in a nitrogen atmosphere with a high-pressure mercury lamp ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd.).

  As a polythiophene-based conductive material, PEDOT-PSS obtained by polymerizing 3,4-ethylenedioxythiophene in the presence of polystyrene sulfonic acid is used, and a polyester diameter resin (trade name: pesresin A-645GH, acrylic-modified polyester 30) is used as a binder. % Aqueous dispersion, manufactured by Takamatsu Yushi Co., Ltd.). Further, 3-glycidoxypropyltriethoxysilane (trade name: KBE-403, manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the silane coupling compound, and wet copper powder (trade name: 1030Y, Mitsui Metals) as the conductive particles. Mining Co., Ltd.) was used.

  Then, a 1% solid dispersion of PEDOT-PSS, a 1% dispersion of a polyester resin diluted with water, a 1% solution of 3-glycidoxypropyltriethoxysilane diluted with methanol, and water 1% dispersion of wet copper powder dispersed in an equal volume of methanol and methanol, and a surfactant diluted with an equal volume of water and methanol (trade name: Surflon S-386, manufactured by AGC Seimi Chemical Co., Ltd.) , 100% active ingredient) and 1% solution. At this time, conductive polymer: binder resin: silane coupling compound: conductive particles: surfactant = 100: 100: 110: 30: 10 were mixed to obtain a mixed solution A. 3% of dimethyl sulfoxide (Kanto Kagaku Co., Ltd., reagent) was mix | blended with this liquid mixture A, and the coating liquid for conductive layer formation was obtained.

On the untreated surface, which is the surface of the substrate having the hard coat layer for the back surface, a coating liquid for forming a conductive layer is applied with a bar coater, and the coating film is dried at 100 ° C. to form a conductive layer. Thus, a conductive sheet in Example 1 was obtained. In addition, the film thickness of the conductive layer was adjusted by the coating amount of the coating liquid for forming the conductive layer so that the surface resistance of the conductive layer was about 400 Ω / sq. At this time, the surface resistance was measured by a method based on JIS K7194 using Loresta EP: MCP-T360 manufactured by Mitsubishi Chemical Analytech Co., Ltd.
[Production of touch panel]
The obtained conductive sheet was cut out to 70 mm × 100 mm to prepare ITO glass with a dot spacer of the same size (surface resistance of about 400Ω / sq). Silver paste (trade name: Doutite FA-401CA, manufactured by Fujikura Kasei Co., Ltd.) was used as a material for forming the extraction electrodes P1 and P2. And the pattern corresponding to the extraction electrode P1 was formed in the conductive surface of the conductive layer with the silver paste, and the pattern corresponding to the extraction electrode P2 was formed in the conductive surface of the ITO glass with the silver paste. Next, the silver paste pattern was baked by heating at 140 ° C. for 15 minutes to form extraction electrodes P1 and P2. Furthermore, a conductive copper foil tape is bonded to each of the extraction electrodes P1 and P2 to form a terminal to which the detection circuit is connected, and an upper electrode in the resistive touch panel and a lower electrode in the resistive touch panel are connected. Obtained. Subsequently, as the adhesive materials G1 and G2, an insulating adhesive tape having a thickness of 100 μm is used, and at the position where the conductive surface of the conductive layer and the conductive surface of the ITO glass face each other, the peripheral portion of the upper electrode and the lower electrode The peripheral part was bonded together to obtain an evaluation resistive touch panel in Example 1.
[Example 2]
As a silane coupling compound, 3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) and 3-mercapto instead of 3-glycidoxypropyltriethoxysilane of Example 1 An 8: 2 mixture of propyltrimethoxysilane (trade name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) was used. Moreover, instead of the wet copper powder of Example 1, silver powder (trade name: SPQ03R, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used as the conductive particles. The configurations other than these silane coupling compound and conductive particles were the same as in Example 1, and the conductive sheet of Example 2 and the resistive film type touch panel of Example 2 were produced.
[Example 3]
As the silane coupling compound, 3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of 3-glycidoxypropyltriethoxysilane of Example 1. Moreover, instead of the wet copper powder of Example 1, silver powder (APS 0.5-1 μm, Wako Pure Chemical Industries, Ltd. reagent) was used as the conductive particles. The configurations other than these silane coupling compounds and conductive particles were the same as in Example 1, and the conductive sheet of Example 3 and the resistive film type touch panel of Example 3 were produced.
[Example 4]
As the silane coupling compound, 3-glycidoxypropyltrimethoxysilane was used instead of 3-glycidoxypropyltriethoxysilane of Example 1. Moreover, instead of the wet copper powder of Example 1, silver powder (trade name: SPQ03R, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used as the conductive particles. The configurations other than these silane coupling compounds and conductive particles were the same as in Example 1, and the conductive sheet of Example 4 and the resistive film type touch panel of Example 4 were produced.
[Examples 5 to 8]
The compounding amount of the silane coupling compound and the compounding amount of the conductive particles were changed as shown in Table 1. And the composition except the compounding quantity of a silane coupling compound and the compounding quantity of conductive particles is the same as that of Example 4, and prepares the coating liquid for conductive layer formation, The coating liquid from which a compounding quantity mutually differs The conductive sheets of Examples 5 to 8 and the resistive film type touch panel of Examples 5 to 8 were prepared using the above.
[Comparative Examples 1-6]
The compounding amount of the silane coupling compound and the compounding amount of the conductive particles were changed as shown in Table 1. And the composition except the compounding quantity of a silane coupling compound and the compounding quantity of conductive particles is the same as that of Example 4, and prepares the coating liquid for conductive layer formation, The coating liquid from which a compounding quantity mutually differs The conductive sheets of Comparative Examples 1 to 6 and the resistive film type touch panels of Comparative Examples 1 to 6 were created using

  In each example and each comparative example, the short axis diameter b of the conductive particles used in each example, the long axis diameter c of the conductive particles, the film thickness a of the conductive layer obtained from each example, the conductive layer Table 1 shows the Si element content and the conductive particle content.

In Table 1, silane coupling compounds and conductive particles are represented by the following symbols.
A1: 3-glycidoxypropyltriethoxysilane A2: 8: 2 mixture of 3-glycidoxypropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane A3: 3-glycidoxypropyltrimethoxysilane B1: wet copper Powder B2: Silver powder B3: Silver powder reagent [Evaluation of conductive sheet and touch panel]
In each example and each comparative example, the conductive sheet and resistive film type touch panel obtained in each example were evaluated by the following methods, and the evaluation results are shown in Table 2.
[Image analysis]
The surface of the conductive layer in the conductive sheet, and the cross section of the conductive layer in the conductive sheet are observed using a scanning electron microscope, and the film thickness a of the conductive layer excluding the convex portions formed by the conductive particles, The short axis diameter b and the long axis diameter c of the conductive particles were confirmed.
[Transmissivity, haze]
The conductive sheet was cut into 5 cm × 10 cm, and the total light transmittance and haze were measured by a method based on JIS-K7105 using a Nippon Denshoku Industries Co., Ltd. haze meter.
[Writing durability]
The touch panel evaluation machine (Touch Panel Laboratories Co., Ltd., Model: 001-29) was attached with the resistive touch panel and 0.8R polyacetal pen obtained in each example, and at 2.5N load, before the writing test. The linearity of the touch panel was measured. Thereafter, with a 5N load, a reciprocating line having a length of 50 mm was written 500,000 times at an oblique angle of 45 ° in a substantially diagonal direction so that the center of the touch panel was included. After such writing, the linearity of the resistive touch panel was measured, and the degree of deterioration was evaluated in three stages according to the following criteria. The linearity measurement is a method in which pressurization is sequentially input to the entire surface of the resistive touch panel, and the accuracy of the resistive touch panel is evaluated based on the magnitude of the maximum deviation of the detection position with respect to the input position.
[Criteria]
A: The change rate of linearity was less than 3%.

B: The change rate of linearity was 3% or more and less than 5%.
C: The linearity change rate was 5% or more and less than 10%.
D: The linearity change rate was 10% or more.
[Contact resistance measurement]
In the resistive touch panel obtained in each example, a load of 2.5 N was input to the center of the touch panel using a 0.8R polyacetal pen, and after 1 minute had elapsed from the start of load input, the extraction electrode P1 and The resistance between the lead electrode P2 was measured as a contact resistance.

表１が示すように、実施例１から実施例８の導電性シートは、塗工液に含まれる導電性粒子の大きさ、および、形状が、上記式１および式３を満たす水準であり、その塗工液によって形成された導電層は、式２を満たす水準である。

As Table 1 shows, the conductive sheets of Examples 1 to 8 are at a level where the size and shape of the conductive particles contained in the coating liquid satisfy the above Formula 1 and Formula 3, The conductive layer formed by the coating solution is at a level that satisfies Equation 2.

  Further, the conductive sheets of Example 1 to Example 8 are at a level that satisfies the above (a) as the blending amount of the conductive particles contained in the coating liquid, and the conductive layer formed by the coating liquid is It is a level which satisfies said (b) as a compounding quantity of the electroconductive particle contained in a conductive layer.

  Further, the conductive sheets of Example 1 to Example 8 are at a level that satisfies the above (c) as the blending amount of the coupling component contained in the coating liquid, and the conductive layer formed by the coating liquid is It is a level that satisfies the above (d) as the blending amount of the coupling component contained in the conductive layer.

  As Table 2 shows, the conductive sheets of Examples 1 to 8 achieve a very high level of contact resistance, that is, touch panel sensitivity and scratch resistance. Moreover, since the contact resistance between the conductive layer and the other conductive member is suppressed, the content of the polythiophene-based conductive agent having a color derived from the π-conjugated bond is suppressed, and the transmittance of the conductive sheet is also increased. Furthermore, since the polythiophene-based conductive agent is the most expensive among the components constituting the conductive layer, it is possible to reduce the cost of the conductive sheet and hence the cost of the touch panel.

  On the other hand, Comparative Examples 1 to 6 are levels at which at least one of the above (a), (b), (c), and (d) is not satisfied. In comparison, the conductivity or scratch resistance of the conductive layer is greatly inferior.

  In addition, in the coating liquid for forming a conductive layer, the present invention is not limited to the above examples, and when the mass part of the polythiophene-based conductive agent is 100, the mass part of the conductive particles is in the range of 20 or more and 100 or less. If it exists, the effect comparable as the said Example 1- Example 8 was recognized in the level by which said (c) is satisfy | filled.

  Moreover, not only the said Example but in a conductive layer, if the content rate which is the mass of the electroconductive particle with respect to the mass of a conductive layer is 6 mass% or more and 25 mass% or less, said (d) will be satisfy | filled. At the same level, the same effects as those in Examples 1 to 8 were observed. Further, in the conductive layer, when the content of the conductive particles with respect to the mass of the conductive layer is less than 6% by mass, the contact resistance tends to decrease rapidly, and the content of the conductive particles with respect to the mass of the conductive layer. At a level exceeding 25% by mass, there was also observed a tendency for the scratch resistance and conductivity to rapidly decrease.

  In addition, in the coating liquid for forming a conductive layer, the present invention is not limited to the above examples, and when the polythiophene-based conductive agent has a mass part of 100, the silane coupling compound has a mass part of 100 or more and 240 or less. If so, the same effects as those of Examples 1 to 8 were observed at a level satisfying the above (a).

  Further, not only in the above embodiment, but in the conductive layer, if the content of silicon element with respect to the mass of the conductive layer is in the range of 3 mass% or more and 7 mass% or less, the level that satisfies the above (b) is satisfied. Thus, the same effect as in Examples 1 to 8 was observed. Further, in the conductive layer, at a level where the content of silicon element relative to the mass of the conductive layer is less than 3% by mass, there is also a tendency for the scratch resistance to decrease rapidly, and the content of silicon element relative to the mass of the conductive layer is At levels exceeding 7% by mass, there was also observed a tendency for the scratch resistance and the conductivity to rapidly decrease.

As mentioned above, according to the said embodiment, the effect listed below is acquired.
(1) In the coating liquid for forming a conductive layer, when the mass part of the polythiophene-based conductive agent is 100, the mass part of the conductive particles is 20 or more and 100 or less. In the coating liquid for forming the conductive layer, when the mass part of the polythiophene-based conductive agent is 100, the mass part of the silane coupling compound is 100 or more and 240 or less. According to the conductive sheet including the conductive layer formed by such a coating liquid and the touch panel including the conductive sheet, the contact resistance between the conductive layer and another conductive member, that is, the sensitivity of the touch panel is increased. And the abrasion resistance in a conductive layer is improved.

  (2) In the conductive layer, the content ratio, which is the mass of the conductive particles with respect to the mass of the conductive layer, is 6% by mass or more and 25% by mass or less. In the conductive layer, the content of silicon element with respect to the mass of the conductive layer is 3% by mass or more and 7% by mass or less. According to the conductive sheet including such a conductive layer and the touch panel including the conductive sheet, the contact resistance between the conductive layer and another conductive member, that is, the sensitivity of the touch panel is increased, and the resistance in the conductive layer is increased. Abrasion is improved.

  DESCRIPTION OF SYMBOLS 10 ... Electroconductive sheet, 11 ... Base material, 12 ... Conductive layer, 13 ... Back surface layer, 14 ... Undercoat layer, 20 ... Resistive touch panel.

Claims (5)

Forming a coating film by applying a coating solution to a substrate;
Drying the coating film to form a conductive layer,
The coating liquid is
Including a polythiophene-based conductive agent, a binder, conductive particles, and a silane coupling compound,
When the mass part of the polythiophene conductive agent is 100,
The mass part of the conductive particles is 20 or more and 100 or less,
The mass part of the silane coupling compound is 100 or more and 240 or less,
In the conductive layer,
The film thickness a of the conductive layer and the minor axis diameter b of the conductive particles are a method for producing a conductive sheet that satisfies the following formulas 1 and 2.
a> 100 nm Formula 1
1.5 <b / a <5 Formula 2 A substrate;
A conductive layer provided on the substrate;
The conductive layer is
A polythiophene-based conductive agent, a binder, conductive particles, a silane coupling compound, and a coupling component that is a reaction product of the silane coupling compound,
The content of the conductive particles is 6% by mass or more and 25% by mass or less,
The content of silicon element is 3% by mass or more and 7% by mass or less,
The conductive sheet satisfying the following formulas 1 and 2 is the film thickness a of the conductive layer and the minor axis diameter b of the conductive particles.
a> 100 nm Formula 1
1.5 <b / a <5 Formula 2 The conductive particles are spherical particles dispersed in the conductive layer,
The conductive sheet according to claim 2, wherein the short axis diameter b of the conductive particles and the long axis diameter c of the conductive particles satisfy the following formula 3.
c / b <2 Equation 3 The conductive particles are:
The conductive sheet according to claim 2 or 3 , wherein the conductive sheet is at least one selected from the group consisting of silver particles, copper particles, silver particles whose surfaces are treated, and copper particles whose surfaces are treated. A touch panel provided with the electroconductive sheet as described in any one of Claim 2 to 4 .

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