WO2019031324A1 - Electrically-conductive sheet and method for manufacturing said electrically conductive-sheet - Google Patents

Abstract

The present invention relates to an electrically-conductive sheet comprising a substrate having two metal wire systems formed thereon. The electrically-conductive sheet comprises a substrate and an electrode layer formed on one side of the substrate. The electrode layer includes a first electrode layer and a second electrode layer. The first electrode layer and the second electrode layer are stacked in this order on the substrate. The first electrode layer comprises a first underlayer comprising a fluorine resin, and first metal wiring formed on the first underlayer surface. The second electrode layer comprises a second underlayer comprising a fluorine resin, and second metal wiring formed on the second underlayer surface. The present invention has a structure in which two electrode layers are formed on one side of the substrate. In this way, compared to conductive sheets of the prior art having a double-side structure, durability with respect to bending and deformation is improved.

Description

Conductive sheet and method of manufacturing the same

The present invention relates to a conductive sheet for forming a touch panel or the like. More specifically, the present invention relates to a conductive sheet including a first and a second two types of metal wires on a substrate, and an electrode layer having those metal wires formed in a two-layer structure on one side of the substrate.

Touch panels have conventionally been used as input devices for various electronic devices such as PCs, tablets, and smartphones. The touch panel is configured of a conductive sheet in which a wire for detecting touch input is formed on a transparent substrate. For this conductive sheet, transparent electrodes such as ITO have been applied as wiring materials until now, but in order to cope with the increase in wiring length due to the recent increase in panel size, the application of metal wiring such as silver or copper with low electrical resistance Is being considered. Although metal is not originally a transparent material, it exhibits transparency equivalent to that of a transparent electrode by forming a micron-order thin line exceeding human visible range.

Conventionally, photolithography has been known as a method of forming metal wiring on various substrates, but the applicant has proposed a method of manufacturing metal wiring using a metal ink having a predetermined configuration including metal particles. (Patent Document 1). In this method of forming a metal wiring, after a liquid repellent fluororesin is applied to a substrate, a functional group (hydrophilic group) is formed at a portion where the metal wiring is to be formed. Then, a metal ink is applied to the substrate to bond metal particles in the ink to a functional group, and the metal particles are sintered to form a metal wiring close to bulk. In this method of forming a metal wiring, light irradiation such as ultraviolet light capable of fine patterning is employed as a method of forming a functional group on the surface of a fluorocarbon resin, whereby high definition wiring can be efficiently manufactured. . Also, in this method, metal particles can be sintered at relatively low temperature to form metal wiring. Therefore, transparent and lightweight resin materials can also be used without concern about thermal damage to the substrate.

By the way, as a configuration of the conductive sheet for the touch panel, it is general that wirings of two systems (X direction, Y direction) which are electrically insulated on the substrate are formed. These wires usually intersect to form a grid-like pattern. And as shown in FIG. 7, the conductive sheet having such two lines of wiring often forms the wiring on the front and back of one substrate, respectively. In such a conductive sheet, the substrate electrically insulates each wiring. For example, Patent Document 2 describes a touch panel including a conductive sheet in which a layer including a first electrode is formed on one surface of a substrate and a layer including a second electrode is formed on the other surface of the substrate. Here, in the specification of the present application, a conductive sheet in which wiring is formed on the front surface and the back surface of a substrate may be referred to as “double-sided structure”.

JP, 2016-48601, A Unexamined-Japanese-Patent No. 2010-39537 JP, 2011-82211, A

However, according to the study of the present inventors et al., The conductive sheet in which the wiring is formed on both sides of the above-described substrate has a problem in durability against deformation (bending). In recent years, flexible and foldable displays and touch panels have been announced. Among such flexible type displays and the like, in addition to touch by a finger, there are some which can be input by bending a screen. The direction of bending at this time is not fixed, and the touch panel is subjected to repeated bending deformation.

When bending deformation is applied to the conventional double-sided conductive sheet, the wires on the front and back sides follow and deform, but the curvature (R) at this time is different on the front and back, and the curvature on the front side of bending becomes large. Therefore, the deformation rates received by the wiring are different on the front side and the back side. And, by repeated bending, there is a possibility that the increase of the resistance value due to the reduction of the cross-sectional area of the wiring and the insulation due to the disconnection occur. In addition, disconnection of wiring may occur not only on one side but also on both sides. As described above, the direction of bending is not fixed. Thus, the conductive sheet having a double-sided structure may cause a problem in the durability of the wiring against bending deformation.

Moreover, although application of metal wiring, such as silver, is examined as a wiring material in a conductive sheet as mentioned above, there exists a problem which concerns on the visibility by light reflection in metal wiring. Since metal such as silver has a high light reflectance, a wiring pattern may be identified by reflected light depending on the angle at which even a very thin wire is viewed. Several measures are known for the problem of such metal wiring, for example, it has been proposed to coat the surface of the metal wiring with a non-reflective material. For example, Patent Document 3 describes that by treating a silver wiring with tellurium hydrochloric acid solution, a blackened layer of a certain thickness is formed on the wiring surface, and it becomes possible to cope with the problem of reflection of metal wiring. ing.

However, the conductive sheet having a double-sided structure can not completely carry out the above-described anti-reflection treatment on the metal wiring. In the double-sided conductive sheet to which the transparent substrate is applied, the user can observe the outer surface of the wiring on one side of the substrate and the interface between the other surface of the substrate and the wiring. And although the reflection prevention of the wiring outer surface of one side is possible with the conductive sheet of a double-sided structure, reflection of the metal wiring of the other side can not be prevented. The above-described anti-reflection treatment is a treatment that acts on the outer surface of the metal wiring, and does not act on the interface between the formed wiring and the substrate. Therefore, only incomplete processing can be performed on the double-sided conductive sheet.

The present invention has been made based on the background as described above, and the conductive sheet in which the first and second two metal wiring lines are formed on the substrate is affected by the metal wiring even if it is bent or deformed. Disclose what is unlikely to occur. In addition, when the metal wiring is subjected to the reflection preventing process, a metal wiring which can be effectively processed is provided. Then, a method of manufacturing such a conductive sheet, which can form a conductive sheet efficiently while forming a high-definition metal wiring, will be clarified.

The problem with the above-described conventional double-sided conductive sheet is that the wiring is formed on each side of the substrate. For the conductive sheet, the substrate is the thickest member that defines the thickness of the entire sheet. Therefore, in order to eliminate the difference in the deformation rate (curvature) received by the wiring at the time of bending deformation, it is conceivable to form both wirings on one side of the substrate to form a two-layer structure.

Here, as a method of forming a metal wiring conventionally known, there is a photolithography method, but this method requires steps of coating and removing a resist. Since the resist removal process is a process of dissolving the resist in a solution, it is impossible to form two layers of metal wiring on one substrate. Therefore, in consideration of application of the photolithography method, as shown in FIG. 1, if two conductive sheets in which one metal wiring is formed on one substrate are laminated, it is possible to form a metal wiring having a formal two-layer structure. With such a configuration, the metal wiring of each conductive sheet can be treated to prevent reflection, so that some of the problems with the double-sided structure can be solved. In addition, about the structure which laminates | stacks two electroconductive sheets which have one metal wiring on one board | substrate in this way, it may be called "layered structure."

However, the conductive sheet of such a laminated structure does not solve the problem of wiring damage in bending deformation. That is, when the upper layer substrate is viewed as a reference, the arrangement relationship of each metal wiring is the same as that of the double-sided structure. In addition, since such a laminated structure uses two substrates, the thickness of the entire conductive sheet is increased. Furthermore, there is a concern that the cost increases due to the production of two conductive sheets.

Then, the inventors of the present invention conducted further studies, and considered the application of the above-mentioned applicant of the present invention to apply the method for forming a metal wiring (Patent Document 1) to which a predetermined fluororesin and metal ink are applied. . Then, the present invention was conceived as a preferable conductive sheet can be obtained by laminating a plurality of electrode layers including the metal wiring formed by this method on one side of the substrate.

That is, the present invention is a conductive sheet having a substrate and an electrode layer formed on one side of the substrate, the electrode layer including a first electrode layer and a second electrode layer, A first electrode layer and a second electrode layer are laminated in this order on a substrate, and the first electrode layer is a first underlayer made of a fluorocarbon resin, and the surface of the first underlayer. And the second electrode layer is formed of a second base layer made of a fluorocarbon resin and a second metal layer formed on the surface of the second base layer. It is a conductive sheet. Hereinafter, the configuration of the conductive sheet according to the present invention will be described in detail.

(I) Configuration of Conductive Sheet According to the Present Invention As described above, the present invention comprises a substrate and an electrode layer formed on one side of the substrate. The electrode layer is formed by laminating the first electrode layer and the second electrode layer. The minimum necessary structure of the conductive sheet of the present invention is as shown in FIG. Each component will be described below. In the specification of the present application, the structure of the conductive sheet according to the present invention may sometimes be referred to as "one-sided two-layer structure" as needed.

(A) Substrate The substrate applied to the conductive sheet of the single-sided two-layer structure of the present invention is not particularly limited, and a substrate made of metal or ceramic can be applied, and further, a resin or plastic substrate can be applied is there. It is also possible to use glass without weight limitations. However, the substrate is preferably made of a transparent material. This is because the present invention is suitably used for display devices such as touch panels and displays.

(B) Electrode Layer In the conductive sheet according to the present invention, two electrode layers are formed on one side of the substrate described above. As a configuration of these electrode layers, the first electrode layer and the second electrode layer are stacked in this order on the substrate. Hereinafter, the configuration of each electrode layer will be described.

(B-1) First electrode layer The first electrode layer is formed on the surface of the substrate, and comprises a first underlayer made of a fluorocarbon resin and a first metal wiring formed on the surface thereof. .

(B-1-1) First Underlayer The first under layer plays a major role in producing the conductive sheet of the present invention, as described in detail below. In the first underlayer made of this fluorocarbon resin, a functional group is formed by a predetermined process with a desired wiring pattern, and metal particles, which are precursors of metal wiring, are fixed thereto. And the fixed metal particle turns into metal wiring. The fluorine resin forming the underlayer is required to have liquid repellency to prevent the metal particles from being fixed to a portion other than the wiring pattern, and reactivity to generate a functional group by a predetermined treatment. . Further, in view of application to a touch panel or the like, it is preferable to have transparency.

In the present invention, the fluororesin to be the underlayer is made of a resin material containing carbon (C) and fluorine (F) in its structural formula. Specifically, a polymer having at least one repeating unit based on a fluorine-containing monomer and having a ratio (F / C) of the number of fluorine atoms to the number of carbon atoms of 1.0 or more is preferable. In the repeating unit of the polymer constituting the fluorine resin of the present invention, the ratio (F / C) of the number of fluorine atoms to the number of carbon atoms of 1.0 or more is required when forming metal wiring in the underlayer. In order to have the liquid repellence. The value of F / C is more preferably 1.5 or more. In addition, about the upper limit of F / C, it is preferable to make an upper limit 2.0 in F / C from the reason of liquid repellency and availability.

The fluorine resin in the present invention preferably contains at least one repeating unit based on the above-mentioned fluorine-containing monomer. If this condition is satisfied, the fluorine resin of the present invention may contain a repeating unit based on a fluorine-containing monomer having an F / C of less than 1.0, and further, a fluorine-free monomer containing no fluorine atom. May contain a repeating unit based on Moreover, the fluorine resin may contain hetero atoms such as oxygen, nitrogen and chlorine in part of the repeating unit based on the fluorine-containing monomer.

Specific examples of the fluorocarbon resin which can satisfy the condition of such constituent elements and F / C include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoro copolymer Examples thereof include ethylene copolymer (ECTFE), tetrafluoroethylene-perfluorodioxole copolymer (TFE / PDD), and a fluorocarbon resin having a cyclic perfluoroalkyl structure or a cyclic perfluoroalkyl ether structure.

Moreover, in addition to the conditions regarding the content of fluorine for securing liquid repellency, it is also preferable to select a suitable fluorine resin in consideration of other characteristics. For example, in consideration of solubility in a solvent when applied to a substrate, it is preferable to use a perfluoro resin having a cyclic structure in its main chain. When the fluorine resin is required to be transparent, it is more preferable to use an amorphous perfluoro resin.

And, a fluorine resin containing at least one oxygen atom (O) in the repeating unit based on the fluorine-containing monomer constituting the polymer is particularly preferable as the fluorine resin to be the underlayer. Such a fluorine resin is particularly preferable because a functional group can be easily and suitably formed when forming a metal wiring on the surface of the underlayer. The upper limit of the number of oxygen atoms in this repeating unit is preferably three.

As a preferable fluorocarbon resin in consideration of these points, perfluorobutenyl vinyl ether polymer (CYTOP (registered trademark): Asahi Glass Co., Ltd.), tetrafluoroethylene-perfluorodioxole copolymer (TFE-PDD) , Teflon (registered trademark) AF: Mitsui-Dupont Fluorochemical Co., Ltd., tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), perfluoroalkoxy polymer (Algoflon (registered trademark): Solvay Japan Ltd.) Etc.

The thickness of the first underlayer, which is made of the above-described fluororesin, is preferably 0.01 μm to 5 μm. If it is less than 0.01 μm, it is difficult to exhibit the liquid-ejecting property. In order to maintain the transparency of the underlayer, the upper limit is preferably about 5 μm. The thickness of the first underlayer is the thickness from the interface between the underlayer and the substrate to the outermost surface of the underlayer, and it is preferable to adopt an average value.

With respect to the conductive sheet according to the present invention, the presence of the underlying layer made of the fluorocarbon resin described above can be confirmed by various analysis means. As analysis means, SIMS (secondary ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), EPMA (electron probe micro analysis), EDX (energy dispersive X-ray analysis), etc. can be applied. For example, elemental analysis of carbon (C) and fluorine (F) is performed at an arbitrary location on the surface of the underlayer or the underlayer in the cross section of the conductive sheet by SIMS to measure the detection intensity of each element and measure the intensity ratio ( F / C) can be calculated to estimate the configuration of the fluorine resin. At this time, when the ratio (F / C) of the detected intensity of fluorine to the detected intensity of carbon is 1.0 or more, the above-mentioned suitable fluororesin (ratio of the number of fluorine atoms to the number of carbon atoms (F / C) It can be determined that the polymer has at least one repeating unit of which 1.0) or more. In addition, in such analysis, it is preferable to analyze at a plurality of places and adopt the average value of the intensity ratio.

(B-1-2) First Metal Wiring The first metal wiring is formed on the underlying layer made of the fluorine resin described above to form a first electrode layer. Here, the first metal wiring is preferably made of at least one of silver, gold, platinum, palladium, copper and nickel as a constituent material thereof. These metals are excellent in conductivity and useful as wiring materials. In particular, silver is preferably applied from the viewpoint of the conductive wire.

The first metal wiring may be an alloy in which each metal is solid-solved or a mixture of each metal, in addition to a metal made of only one metal among the above-described metals. The metal wiring may have a single layer structure, but may have a multilayer structure. When it is set as a multilayer structure, you may form with a same metal, and you may form with a different metal.

Furthermore, the first metal wiring may be provided with another metal or compound on its surface to prevent reflection. The metal or compound for preventing reflection may form a layer, or may be dispersed in the form of particles. In addition, in order to stabilize the surface state of the first metal wiring, a monomolecular film of a thiol compound, a fatty acid or the like may be formed.

The dimensions (thickness, line width) of the first metal wiring are not limited. Also, the shape of the wiring pattern is not particularly limited. In addition, in consideration of applications such as a touch panel and the like, fine wires in the micron order exceeding the visible region are preferable, and therefore, the width of the metal wiring is preferably 0.5 μm or more and 8.0 μm or less. Further, the thickness of the metal wiring is preferably 0.1 μm or more and 1.0 μm or less. When forming a multilayer metal wiring, the total thickness is preferably in the above range. The width and thickness of the metal wiring are preferably defined by an average value.

In addition, as for the metal wiring in this invention, what was formed by the formation method (patent document 1) of the metal wiring by the above-mentioned applicant of this application mentioned above is preferable. In this method, after applying the ink in which the metal particles are dispersed in the solvent, the metal particles are sintered to form the metal wiring. The metal wiring is made of a dense bulky thin film free of voids due to sintering while using metal particles as a precursor. At this time, the purity of the metal (silver and copper) constituting the metal wiring is 99% by mass or more.

(B-2) Second Electrode Layer A feature of the conductive sheet according to the present invention is that a second electrode layer is laminated on the first electrode layer to form a single-sided two-layer structure. . The second electrode layer has the same configuration as the second electrode layer, and includes a second underlayer made of fluorocarbon resin and a second metal wire.

(B-2-1) Second Underlayer The configuration of the fluorine resin to be the second under layer of the second electrode layer is basically the same as that of the first under layer. That is, a repeating unit containing carbon (C) and fluorine (F) and based on a fluorine-containing monomer, wherein the ratio of the number of fluorine atoms to the number of carbon atoms (F / C) is 1.0 or more Polymers having at least one unit are preferred. Moreover, what contains at least 1 oxygen atom (O) in the repeating unit based on this fluorine-containing monomer is preferable. Preferred specific examples of the fluorine resin applied to the second underlayer are also the same as the first underlayer.

The fluorocarbon resin of the second underlayer may be the same as the fluorocarbon resin of the first underlayer. Moreover, as long as it is a fluorine resin having the above-described preferable configuration, the fluorine resin of the second underlayer may be a fluorine resin different from the first underlayer.

The thickness of the second underlayer is an important matter in the context of the first underlayer. The second underlayer may have the same thickness as the first underlayer, but is preferably 0.04 μm or more and 1 μm or less. That is, the preferred range of the thickness of the second underlayer is narrower than the preferred range of the thickness of the underlayer of the first electrode layer.

As described above, the lower limit (0.04 μm) of the thickness of the second underlayer is preferably thicker than the lower limit (0.01 μm) of the thickness of the first underlayer. This is because, if the second underlayer is too thin, the metal wiring (second metal wiring) formed thereon may not have the designed line width. Specifically, in forming the second metal wiring, the exposure process is performed on the surface of the second underlayer to form a functional group. At this time, if the second underlayer is too thin, adhesion with a photomask for exposure processing may be insufficient, and an exposure pattern with a desired line width may not be formed. As a result, the line width of the second wiring may be increased in whole or in part. Moreover, in addition to the problem of the quality of such metal wiring, when the second underlayer is too thin, a break may occur in the vicinity of the underlayer when the conductive sheet is subjected to bending deformation. For the above reasons, the lower limit value of the second underlying layer thickness is set.

On the other hand, the upper limit (1 μm) of the thickness of the second underlayer is preferably thinner than the upper limit (5 μm) of the thickness of the first underlayer. This is because when the second underlayer is excessively thick, the difference in the deformation rate (curvature) of the metal wiring at the time of deformation of the conductive sheet becomes large, and it becomes difficult to secure the bending strength of the conductive sheet. In addition, when the second underlayer is excessively thick, the transparency may be impaired. As described above, in the present invention, the first and second electrode layers are stacked, but it is preferable to set conditions in consideration of the influence of the second underlayer, instead of simply stacking the first and second electrode layers.

The thickness of the second underlayer means the interface between the second underlayer and the first metal wiring, or the interface between the second underlayer and the intermediate layer when the intermediate layer described later is applied. The starting point is the distance from this starting point to the outermost surface of the second underlayer. As for the thickness of the second underlayer, it is preferable to adopt an average value at a plurality of places.

(B-2-2) Second Metal Wiring It is preferable to apply the same configuration as the first metal wiring also to the second metal wiring. That is, the second metal wiring is preferably made of at least one of silver, gold, platinum, palladium, copper and nickel. The second metal wiring may be made of only one of these metals, or may be an alloy / mixture. In addition, a single layer structure or a multilayer structure can be employed. Furthermore, other metals and compounds may be provided on the metal wiring.

In addition, the size and shape of the second metal wiring are not limited. Therefore, the width of the second metal wiring is preferably 0.5 μm or more and 8.0 μm or less. The thickness of the second metal wiring is preferably 0.1 μm or more and 1.0 μm or less.

The second metal wire may be made of the same metal as the first metal wire, but a different metal may be applied. For example, copper may be applied to the second metal interconnection while silver is applied to the first metal interconnection. Although the pattern shape of the metal wiring is not restricted either, it is general that the first metal wiring and the second metal wiring intersect to form a mesh pattern.

Here, as a preferable form of the second electrode layer in relation to the first electrode layer, it is preferable to set the distance between them to 1.2 μm or more and 4.5 μm or less. The interlayer distance is the distance between the bottom of the first metal wire and the bottom of the second metal wire. As described above, when the interlayer distance between the first electrode layer and the second electrode layer is defined as too small, a location where the capacitance of the conductive sheet becomes excessive locally occurs if the interlayer distance is too small. This is because a difference in sensor sensitivity may occur internally, which may cause a malfunction. In the present case, while employing a single-sided two-layer structure, layers made of fluorocarbon resin are formed as the first and second underlayers. The lower limit value of the interlayer distance was set as described above in order to secure the in-plane stability of the capacitance in consideration of the influence of each of the configurations.

On the other hand, the upper limit value of the interlayer distance is set as described above. If the interlayer distance is too large, the second metal wiring may be broken due to bending deformation. Moreover, it is because it violates the shortening of the conductive sheet.

(B-4) Optional Configuration of Electrode Layer As described above, the electrode layer of the present invention basically has two layers of the first electrode layer and the second electrode layer. However, in the present invention, in addition to these, the presence of another configuration is optionally permitted. Specifically, an intermediate layer between the first electrode layer and the second electrode layer, and a coating layer on the second electrode layer can be mentioned.

(B-4-1) Intermediate Layer The conductive sheet of the present invention can include at least one intermediate layer made of a dielectric or an insulator between the first electrode layer and the second electrode layer. The intermediate layer is formed on the first metal wiring of the first electrode layer for the purpose of preventing migration, preventing moisture, preventing oxidation, preventing peeling, and the like. Further, application of the intermediate layer may be applied to secure smoothness when forming the second electrode layer (second base layer) simultaneously with the various functions described above. In addition, by applying the intermediate layer on the first electrode layer, the surface on which the second underlayer is formed can be made flat, and the underlayer can be formed uniformly. In order to make the second underlayer flat, a fluorine resin to be the second underlayer may be thickly coated on the first electrode layer. However, in this case, the second underlayer may be excessively thick. In addition, many fluorocarbon resins suitable as the underlayer in the present invention are expensive. The intermediate layer also has an effect of adjusting the manufacturing cost of the conductive sheet while securing the flatness of the second underlayer.

As a material of the intermediate | middle layer which exhibits the said function, resin, such as a fluoro resin, an acrylic resin, an epoxy resin, an alkyd resin, a vinyl resin, a phenol resin, a silicon resin, is mentioned, for example. In particular, it is preferable to apply an intermediate layer for preventing migration. Specific examples of this migration inhibitor include fluororesins of trade names such as DURASURF (manufactured by Herbes Co., Ltd.), KP-911 (manufactured by Shin-Etsu Chemical Co., Ltd.), and METAX (manufactured by Kanto Kasei Co., Ltd.). Also known are migration inhibitors containing sulfur compounds such as methanethiol, ethanethiol, thiophenol, cysteine, glutathione, decanethiol, octadecanethiol, triazinethiol and the like.

The intermediate layer may have various functions as described above, and may use one type of material alone to perform a plurality of functions. The intermediate layer may be formed of a single layer, but a plurality of types may be combined and applied. The thickness of the intermediate layer is preferably 1 μm to 3 μm in total. When the intermediate layer is less than 1 μm, in particular, when the conductive sheet is bent and deformed, the first metal wiring and the second metal wiring may be connected. In addition, the thickness of the intermediate layer affects the interlayer distance (the distance between the bottom surface of the first metal wiring and the bottom surface of the second metal wiring). Therefore, considering this point, the thickness of the intermediate layer is 1 μm It is preferable to set it as the above.

On the other hand, if the thickness of the intermediate layer is increased, there is a concern that the second metal wiring may be broken at the time of bending deformation. In addition, the intermediate layer may need to be baked after application depending on the material to be applied. At this time, if the thickness of the intermediate layer is excessive, the amount of contraction at the time of firing becomes large, and the first electrode layer therebelow may be deformed to cause disconnection. From this, it is preferable to set the thickness of the intermediate layer to 3 μm as the upper limit. The thickness of the intermediate layer is the distance between the interface between the intermediate layer and the first metal wiring and the outermost surface of the intermediate layer. It is preferable to adopt an average value of a plurality of places as this thickness.

(B-4-2) Coating Layer The electrode layer of the conductive sheet according to the present invention can include at least one coating layer on the surface of the second electrode layer, in addition to the above-described intermediate layer. This coating layer also has the same function as the intermediate layer, and is formed for the purpose of preventing migration, preventing moisture, preventing oxidation, preventing peeling, and the like for the second metal wiring of the second electrode layer. Therefore, the same material as the intermediate layer can be applied. Also, since the coating layer is different from the intermediate layer and close to the outermost surface of the conductive sheet, a relatively hard top coat may be applied for scratch prevention, adhesion with other films, and the like. The material of the top coat may, for example, be a fluorine resin, an acrylic resin, an epoxy resin, an alkyd resin, a vinyl resin, a phenol resin or a silicon resin.

The coating layer may also be formed as a single layer, or a plurality of types may be combined and applied. The thickness of the coating layer can be adjusted depending on the application and the material used, but it is preferable that the total thickness is 1 μm or more and 3 μm or less. For example, it is preferable to set it as the said range for wound prevention of a 2nd electrode layer. The thickness of the coating layer is the distance between the interface between the coating layer and the second metal wiring and the outermost surface of the coating layer. It is preferable to adopt an average value of a plurality of places as this thickness.

An example of the conductive sheet according to the present invention including the intermediate layer and the coating layer described above is shown in FIG. In this figure, the meaning of the thickness of the intermediate layer and the coating layer is also added to help understand them.

(II) Characteristics and Use Aspects of the Conductive Sheet According to the Present Invention The conductive sheet according to the present invention described above comprises the base material and the electrode layer (first and second underlayers, metal wiring, intermediate layer, coating layer) It is preferable to have transparency by appropriately adjusting the material and thickness of each component. As a specific reference, the total light transmittance based on JIS K7361-1 when incident from the second electrode layer side is 85% or more. It is preferable that this transmittance | permeability makes a light enter from the 2nd electrode layer side using a turbidity meter (cloudiness meter), measures it, and it is preferable to employ | adopt two or more average value.

A particularly preferred mode of use of the conductive sheet according to the present invention described above is a component of a touch panel. For example, a touch panel can be formed by bonding a cover glass or a protective film to the conductive sheet according to the present invention, bonding a connection connector (FPC connector or the like), and further connecting to an external controller IC. An example of the process of comprising a touch panel from the electroconductive sheet which concerns on FIG. 4 at this invention is demonstrated. The touch panel including the conductive sheet of the present invention is excellent in the resistance to the damage of the electrode due to the bending deformation, and can be made thin by optimizing the thickness of each layer.

(III) Method of Manufacturing Conductive Sheet According to the Present Invention Next, a method of manufacturing a conductive sheet according to the present invention will be described. As described above, the conductive sheet according to the present invention is formed by sequentially applying the first and second electrode layers on one side of the substrate by applying the above-described method of forming a metal wiring (Patent Document 1) by the applicant of the present invention. Manufactured by laminating. That is, the method for producing a conductive sheet according to the present invention includes the steps of forming a first electrode layer and a second electrode layer in this order on one side of a substrate, and forming the first and second electrode layers This is a method of producing a conductive sheet by a method including the following steps (a) to (c).

(A) A step of applying a fluorine resin to a substrate to form an underlayer.
(B) forming a functional group at a portion of the underlying layer where the metal wiring is formed.
(C) A metal ink comprising a protective agent A comprising an amine compound and metal fine particles protected by a protective agent B comprising a fatty acid dispersed in a solvent is applied to the surface of the substrate, and the metal fine particles are applied to the underlayer. The process of forming metal wiring by fixing.

Here, the steps of forming the first and second electrode layers of (a) to (c) will be described in detail with respect to the method of the present invention. In forming each electrode layer, first, a fluorine resin is applied to the substrate to form an underlayer (step (a)). The materials and the like of the substrate and the fluorine resin are as described above.

In the case of application | coating of a fluorine resin, it can respond by apply | coating what melt | dissolved the fluorine resin in the suitable solvent. After application, baking is performed to form an underlayer made of a fluorocarbon resin. It does not specifically limit as a coating method of a fluorine resin, such as dipping, a spin coat, a roll coater. After the fluorine resin is applied, appropriate post-treatments (drying and baking) are performed to form an underlayer. The above-described application of the fluorine resin is performed at least in the region where the metal wiring is to be formed, and does not necessarily have to be applied over the entire surface of the substrate.

Next, functional groups are formed on the surface of the fluorocarbon resin which is the underlayer (step (b)). This functional group is a functional group formed by cleaving the covalent bond of the fluorocarbon resin. Specifically, a carboxy group, a hydroxy group and a carbonyl group are formed.

As a treatment method of functional group formation to the fluorocarbon resin surface, it is by ultraviolet irradiation, corona discharge treatment, plasma discharge treatment, excimer laser irradiation. In these treatments, a photochemical reaction is caused on the surface of the fluorine resin to break covalent bonds, and it is necessary that the treatment is appropriate energy application treatment. The amount of energy applied to the pattern forming portion is preferably about 1 mJ / cm ² or more and 4000 mJ / cm ² or less. For example, in the case of UV irradiation, UV irradiation with a wavelength of 10 nm or more and 380 nm or less is preferable, and particularly preferably, UV light with a wavelength of 100 nm or more and 200 nm or less is irradiated.

In the irradiation of ultraviolet light onto the surface of the fluorine resin, an exposure process using a photomask (reticle) is generally performed. In the present invention, as the exposure method, either a non-contact exposure method (proximity exposure, projection exposure) or a contact exposure method (contact exposure) can be applied. In proximity exposure, the distance between the mask and the surface of the fluorine resin is preferably 10 μm or less, more preferably 3 μm or less.

As described above, after forming the base layer made of fluorocarbon resin on the substrate and performing the functional group formation processing on the metal wiring formation portion, the substrate is brought into contact with the metal ink to form the metal wiring ((c) Process). The metal ink is a metal particle dispersion liquid in which a metal particle in a bonding state with a predetermined protective agent is dispersed in a solvent. In order to appropriately form the metal wiring in the present invention, the configuration of a suitable metal ink is as follows.

In the metal ink, the dispersed metal particles are made of at least one of silver, gold, platinum, palladium and copper as described above. The metal particles preferably have an average particle diameter of 0.005 μm (5 nm) or more and 0.1 μm (100 nm or less). In order to form a fine wiring pattern, the particle diameter is preferably 0.03 μm (30 nm) or less. On the other hand, excessively fine metal particles are easily aggregated and inferior in handleability.

The protective agent used in the metal ink is an additive for suppressing aggregation and coarsening of metal particles and stabilizing the dispersion state. The aggregation and coarsening of the metal particles not only cause the metal to precipitate during storage and use of the dispersion, but also must be avoided from affecting the sintering characteristics after bonding to the substrate. Further, in the present invention, the protective agent also acts as a marker for fixing the metal by substituting the functional group on the surface of the underlayer made of a fluorocarbon resin on the substrate.

Here, as the protective agent for the metal ink used in the present invention, it is preferable to use two kinds of compounds having different basic structures in combination. Specifically, it is preferable to use two kinds of protecting agents, protecting agent A and protecting agent B, to apply an amine as the protecting agent A and a fatty acid as the protecting agent B.

The amine compound which is the protective agent A preferably has a total carbon number of 4 or more and 12 or less. This is because the carbon number of the amine affects the stability of the metal particles and the sintering characteristics during pattern formation.

Further, as the number of amino groups in the amine compound, (mono) amine having one amino group or diamine having two amino groups can be applied. In addition, the number of hydrocarbon groups bonded to the amino group is preferably one or two, that is, a primary amine (RNH ₂ ) or a secondary amine (R ₂ NH) is preferable. And when applying a diamine as a protecting agent, the thing of a primary amine or a secondary amine whose at least 1 or more amino group is primary is preferable. The hydrocarbon group bonded to the amino group may be a chain hydrocarbon having a linear structure or a branched structure, or may be a hydrocarbon group having a cyclic structure. In addition, oxygen may be contained in part.

Specific examples of the amine compound applied as a protective agent in the present invention include butylamine (C4), 1,4-diaminobutane (C4), 3-methoxypropylamine (C4), pentylamine (C4) Carbon number 5), 2,2-dimethylpropylamine (carbon number 5), 3-ethoxypropylamine (carbon number 5), N, N-dimethyl-1,3-diaminopropane (carbon number 5), hexylamine (carbon number 5) C6), heptylamine (C7), benzylamine (C7), N, N-diethyl-1,3-diaminopropane (C7), octylamine (C8), 2-ethylhexyl Amine (carbon number 8), nonylamine (carbon number 9), decylamine (carbon number 10), diaminodecane (carbon number 10), undecylamine (carbon number 11), dodecylamine (12 carbon atoms), diamino dodecane (having 12 carbon atoms) and the like. The amine compound which is the protective agent A may be used in combination or in combination with one another for the purpose of controlling the dispersibility of the metal particles in the dispersion and the low temperature sinterability. Moreover, the total of carbon number should just contain at least 1 sort (s) of 4 or more and 12 or less amine compound, and if so, the amine compound of carbon number out of the said range may exist.

On the other hand, the fatty acid applied as the protective agent B acts as an auxiliary protective agent for the amine compound in the dispersion to enhance the stability of the metal particles. The effect of the fatty acid appears clearly after the metal particles are applied to the substrate, and the addition of the fatty acid can form a metal pattern with a uniform film thickness. This effect can be clearly understood in contrast to the case where metal particles without fatty acid are applied, and metal particles without fatty acid can not form a stable metal pattern.

The fatty acid is preferably a saturated fatty acid or unsaturated fatty acid having 4 to 26 carbon atoms. Specific examples of preferred fatty acids include butanoic acid (C4), pentanoic acid (C5), hexanoic acid (C6), heptanoic acid (C7), octanoic acid (C8), Nonanoic acid (carbon number 9), decanoic acid (alias: capric acid, carbon number 10), undecanoic acid (alias: undecylic acid, carbon number 11), dodecanoic acid (alias: lauric acid, carbon number 12), tridecanoic acid ( Aliases: Tridecyl acid, 13 carbon atoms, tetradecanoic acid (alias: myristic acid, 14 carbon atoms), pentadecanoic acid (alias: pentadecyl acid, 15 carbon atoms), hexadecanoic acid (alias: palmitic acid, 16 carbon atoms), heptadecane Acid (alias: margaric acid, carbon number 17), octadecanoic acid (alias: stearic acid, carbon number 18), nonadecanoic acid (alia: nonadecyl acid, carbon number 19), San acid (aka: arachidic acid, carbon number 20), behenic acid (aka: docosanoic acid, carbon number 22), lignoceric acid (aka: tetracosanoic acid, carbon number 24), hexacosanoic acid (aka: serotic acid, carbon number 26) Etc., palmitoleic acid (C16), oleic acid (C18), linoleic acid (C18), linolenic acid (C18), arachidonic acid (C20), erucic acid (carbon) And unsaturated fatty acids such as nervonic acid (alias: cis-15-tetracosenoic acid, carbon number 24). Particularly preferred are oleic acid, linoleic acid, stearic acid, lauric acid, butanoic acid and erucic acid. Also with regard to the fatty acid to be the protective agent B described above, plural kinds of fatty acids may be used in combination. In addition, it is sufficient if it contains at least one kind of unsaturated fatty acid or saturated fatty acid having 4 to 24 carbon atoms, and if so, other fatty acids may be present.

The metal ink protected by the protective agent A and the protective agent B described above is dispersed in a solvent to constitute a metal ink. The solvent applicable here is an organic solvent, for example, alcohol, benzene, toluene, alkane and the like. You may mix these. Preferred solvents are alkanes such as hexane, heptane, octane, nonane and decane, alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol and the like, more preferably among these And a mixed solvent of one or more alcohols selected from and one or more alkanes.

The content of the metal particles in the metal ink is preferably 20% by mass or more and 60% by mass or less in terms of the metal mass with respect to the liquid mass. If the content of the metal particles is less than 20%, a metal pattern having a uniform film thickness for securing sufficient conductivity can not be formed in the pattern forming portion, and the resistance value of the metal pattern becomes high. . When the content of the metal particles exceeds 60%, it becomes difficult to form a stable metal pattern due to aggregation and enlargement of the metal particles.

The content of the protective agent of the metal ink is preferably defined on the basis of the mass of the metal in the metal ink. And about the amine compound which is protective agent A, it is preferable to set it as 0.08 mmol / g or more and 3.0 mmol / g or less based on metal mass. Moreover, it is preferable that content of the fatty acid which is the protective agent B sets it as 0.008 mmol / g or more and 0.5 mmol / g or less on a metal mass basis. The content of the protective agent in the metal ink does not affect the dispersibility of the metal particles even if the content of the protective agent exceeds the above preferable range, but the excess protective agent causes the low temperature sinterability of the metal particles and the formed metal pattern The above range is preferable because it affects the resistance value of In addition, about the number-of-moles of said protective agent, when using several types of amine compounds and a fatty acid, a total number-of-moles is applied, respectively.

In the metal wiring formation step, the metal ink described above is applied to a substrate subjected to a process such as exposure. The ink may be applied by dipping, spin coating, or roll coating, but the ink may be dropped and spread using an application member such as a blade, squeegee or spatula. In the present invention, a functional group for selectively fixing metal particles to a pattern formation portion is formed in advance, and a pattern can be formed efficiently by spreading the dispersion liquid at a stretch.

The metal ink is repelled by its liquid repellence on the basis of a fluorine resin having no functional group. When an application member such as a blade is used, the repelled dispersion is removed from the substrate surface. On the other hand, in the pattern formation portion in which the functional group is formed, a substitution reaction of the protective agent of the metal particle and the functional group occurs, and the first metal particle is fixed to the substrate. Thereafter, the solvent of the dispersion is evaporated, and the first metal particles on the substrate are self-sintered to form a metal film, whereby a metal pattern is formed.

Since this self-sintering is a phenomenon that occurs even at room temperature, heating of the substrate is not an essential step in forming a metal pattern. However, by baking the metal pattern after self-sintering, the protective agent (amine compound, fatty acid) remaining in the metal film can be completely removed, whereby the resistance value can be reduced. It is preferable to perform this baking process at 40 degreeC or more and 250 degreeC. If it is less than 40 ° C., it is not preferable because the removal and volatilization of the protective agent take a long time. When the temperature exceeds 250 ° C., the resin substrate or the like becomes a factor of deformation. The firing time is preferably 3 minutes or more and 120 minutes or less. The firing step may be performed in the air or in a vacuum.

By the application of the metal ink as described above and the sintering / bonding of the metal particles, a metal wiring is formed and a first electrode layer is formed.

After forming the first electrode layer, the second electrode layer can be formed by performing the steps (a) to (c) as described above.

Here, when forming the second electrode layer, when it is necessary to treat the surface of the first metal wiring, for example, in order to prevent reflection of the metal wiring, processing such as adjusting the surface roughness of the metal wiring and forming a compound In the case of performing the process, the process is performed before forming the second electrode layer.

Also, in the case of setting an intermediate layer, the intermediate layer is formed before forming the second electrode layer. The intermediate layer is, as described above, a dielectric or an insulator for the purpose of preventing migration of the first metal wiring or the like, and is applied according to the respective materials. The intermediate layer can also cover the surface of the first electrode layer and contribute to the planarization of the second underlayer.

After the surface treatment of the first metal wiring and the formation treatment of the intermediate layer as necessary, the second electrode layer is formed by the steps (a) to (c). Here, the contents of the fluorine resin application (step (a) step), the functional group formation treatment (step (b) step), and the application / sintering of metal ink (step (c) step) are the same as in the second electrode layer. Is applied.

However, as for the second underlayer, as described above, since the range of thickness suitable for the first underlayer is limited, it is preferable to adjust the coating amount. In addition, it is preferable that the second underlayer be excellent in flatness. In this respect, when the intermediate layer is applied and formed, the flatness of the second underlayer is influenced by the thickness unevenness of the intermediate layer and the surface state. Therefore, it is preferable to diselectrify the surface of the intermediate layer with an eliminator (ionizer) and then to apply a fluorocarbon resin to be the second underlayer. Since the fluorocarbon resin of the base layer is easily charged with static electricity, a uniform coating layer can be formed by discharging the coating surface. It is preferable to perform this static elimination process in 1 second or more and 120 seconds or less. Also, the second underlayer may be applied thicker without forming the intermediate layer, but in this case, after applying the fluorocarbon resin, it is allowed to stand for a fixed time (5 seconds or more) to homogenize the coating film. Then, it is preferable to carry out the subsequent step (b).

In the same manner as the first electrode layer after formation of the second underlayer (step (a)), functional group formation treatment (step (b)), coating and sintering of metal ink (step (c)) As a result, the second electrode layer is formed, and the conductive sheet according to the present invention is manufactured. Incidentally, after the formation of the second electrode layer, the surface treatment (antireflection treatment etc.) of the second metal wiring and the formation treatment of the coating layer can be appropriately performed.

The conductive sheet according to the present invention described above is provided with two electrode layers on one side of the substrate, and has durability against bending of a conventional double-sided conductive sheet. In addition, by making the configuration of the base layer or the like of the fluorine resin appropriate, it is possible to cope with the thinning of the conductive sheet.

The figure explaining the structure of the conductive sheet on which the conventional conductive sheet was laminated (laminated structure). The figure which demonstrates the minimum structure (single-sided 2 layer structure) about the electroconductive sheet which concerns on this invention. The figure which demonstrates the front gun-like structure containing an intermediate | middle layer and a coating layer about the electroconductive sheet which concerns on this invention. A figure explaining an example of composition of a touch panel using a conductive sheet concerning the present invention. The figure which shows the external appearance of the electroconductive sheet (single-sided 2 layer structure) manufactured in 1st Embodiment. The figure which shows the external appearance of the electroconductive sheet (double-sided structure) manufactured by the comparative example. The figure explaining the structure (double-sided structure) of the conventional electrically conductive sheet.

First Embodiment A preferred embodiment of the present invention will be described below. In this embodiment, a base layer made of fluorocarbon resin is formed on a transparent substrate, and a silver ink is applied to form a metal wiring made of silver, thereby producing a conductive sheet having a single-sided two-layer structure.

[Manufacturing of silver ink]
In the present embodiment, silver ink is used as the metal ink. The silver ink is obtained by dispersing silver particles produced by a thermal decomposition method in a solvent. In this thermal decomposition method, a silver compound having thermal decomposition properties such as silver oxalate (Ag ₂ C ₂ O ₄ ) is used as a starting material, and a silver compound and a protective agent are reacted to form a silver complex, which is then used as a precursor. It is a method of obtaining silver particles by heating and decomposing as a body.

In the production of silver particles, first, 0.651 g of decane was added to and wetted with 1.519 g of silver oxalate (1.079 g of silver) as a starting material. Then, an amine compound as a protective agent and a fatty acid were added to the silver oxalate. Specifically, after first adding N, N-dimethyl-1,3-diaminopropane (0.778 g) and kneading for a while, further hexylamine (1.156 g), dodecylamine (0.176 g), olein The acid (0.042 g) was added and kneaded, and then heated and stirred at 110 ° C. During heating and stirring, the cream silver complex gradually turned brown and turned to black. This heating and stirring operation was performed until the generation of bubbles from the reaction system disappeared. After completion of the reaction, the reaction system was allowed to cool to room temperature, methanol was added thereto, and the mixture was sufficiently stirred, followed by centrifugation to remove excess protecting agent, and the silver fine particles were purified. The addition of methanol and the purification of silver fine particles by centrifugation were performed again to obtain silver fine particles as a precipitate.

Then, a mixed solvent of octane and butanol (octane: butanol = 4: 1 (volume ratio)) was added to the produced silver fine particles to obtain a silver ink. The silver concentration of this silver ink was 40% by mass.

The above-described metal ink was used to produce a single-sided two-layer conductive sheet. FIG. 5 shows the appearance of the conductive sheet manufactured in the present embodiment. As the conductive sheet, a transparent resin substrate (dimension: 210 mm × 297 mm, thickness 50 μm) made of polyethylene terephthalate (PET) was used as a substrate. Then, a first electrode layer is formed in a 12.5 mm × 16.3 mm area on the substrate, and a second electrode layer is further formed in a 9.0 mm × 16.3 mm area on the first electrode layer. It formed. The dimensions (horizontal widths) of the first electrode layer and the second electrode layer are different in order to measure the resistance value of the metal wiring of each electrode layer.

[Formation of first electrode layer]
First, the first electrode layer on the resin substrate was formed. After applying an amorphous perfluorobutenyl ether polymer (CYTOP (registered trademark): manufactured by Asahi Glass Co., Ltd.) as a fluorine resin to a substrate by a spin coating method (rotational speed 2000 rpm, 20 sec), 10 minutes at 50 ° C. Subsequently, the resultant was heated at 80 ° C. for 10 minutes, and further baked at 140 ° C. for 10 minutes in an oven. As a result, an underlayer of 0.06 μm (60 nm) made of fluororesin was formed.

Next, a photomask of a comb-shaped wiring pattern (line width 2.0 μm, line interval 300 μm) is adhered to the surface of the substrate on which the base layer is formed (contact exposure of mask-substrate distance 0), It was irradiated with ultraviolet light (VUV light). VUV light was irradiated at a wavelength of 172 nm and 11 mW / cm ² for 20 seconds.

The silver ink described above was applied to the substrate having the functional group formed on the surface of the underlayer as described above. In the application, the dispersion was wetted and spread in advance at the contact portion between the substrate and the blade (made of glass), and then the blade was swept in one direction. Here, the sweep speed is 2 mm / sec. It was confirmed by the application by the blade that the ink was adhering only to the ultraviolet ray irradiated portion (functional group forming portion) of the substrate. Then, the substrate was subjected to hot air drying at 120 ° C. to form silver wiring. The thickness of the silver wiring was 0.04 μm (40 nm), and the line width was 2.0 μm.

On the substrate on which the first electrode layer was formed as described above, an acrylic resin (TKK-1001 HSC: manufactured by JGC Corporation) was applied as an intermediate layer. The acrylic resin was adjusted to have a maximum film thickness of 1 μm after coating. The film thickness is set to 1 μm in order to smooth the surface on which the second electrode layer is formed while considering the thickness of the metal wiring of the first electrode layer.

[Formation of Second Electrode Layer]
The second electrode layer was formed on the substrate coated with the intermediate layer as described above. In the present embodiment, the same fluorocarbon resin as that for the first underlayer is applied onto the intermediate layer. A fluorine resin was applied to a designated area on the substrate (intermediate layer) to form an underlayer. The fluorine resin coating method was the same as that of the first electrode layer, and the thickness of the base layer was also 0.06 μm (60 nm).

Then, in the same manner as when the first electrode layer was formed, a photomask of a comb-shaped wiring pattern was adhered, and ultraviolet light was irradiated thereto. Furthermore, the silver ink described above was applied. The coating conditions were the same as for the first electrode layer, and the substrate was dried with hot air at 120 ° C. to form a silver wiring (thickness 0.04 μm, line width 2.0 μm).

Comparative Example 1 A conductive sheet having a double-sided structure was manufactured as a comparative example of the conductive sheet according to the present embodiment. The same PET substrate as this embodiment was prepared, and the electrode layer was formed in the process similar to this embodiment on the both surfaces. First, a fluorocarbon resin (CYTOP (registered trademark)) was applied to a region of 13.5 mm × 17.3 mm with a bar coater and baked to form a 0.06 μm fluorocarbon underlayer. A photomask with a comb-like wiring pattern (line width: 2.0 μm, line spacing: 300 μm) similar to that of the present embodiment was adhered to the surface of the underlayer and exposed. Thereafter, the silver ink described above was applied, and the substrate was dried with hot air at 120 ° C. to form a silver electrode (line width: 2.0 μm).

Next, a fluorine resin was applied to the area of the other surface of the substrate: 13.5 mm × 17.3 mm to form a base layer, and after exposure, a silver ink was applied to form a second electrode layer. . As described above, a double-sided conductive sheet having electrode layers on both sides of the substrate was produced. The configuration of the conductive sheet of this comparative example is shown in FIG.

[Bending test]
A bending test was performed on the conductive sheets of the present embodiment and the comparative example 1 manufactured above, and durability against deformation was examined. In the bending test, the terminal is connected at a position of 10 mm from the end of the first electrode layer of the manufactured conductive sheet and at a position of 10 mm from the opposite end, and at a position of 5 mm on both sides from the center line of the substrate of the second electrode layer. I decided. In the bending test, first, the resistance value of the metal wiring of each electrode layer before the test was measured by a digital tester.

Then, the bending radius of the sheet was 2 mm, and bending was performed along the center line of the substrate of the conductive sheet. The number of times of bending was 100,000 bendings, with the bending process in which the film expanded and contracted into a U-shape counted as one bending. And about the conductive sheet after this bending test, the resistance value of the silver wiring of the electrode layer of each layer was measured by the digital tester. The results of this bending test are shown in Table 1.

From Table 1, the conductive sheet of this embodiment was not damaged in the first and second metal wirings even after being subjected to 100,000 bending tests. Although there was an increase in the resistance value of the metal wiring, no problem occurred in the energization. On the other hand, in the comparative example, after the bending test, it was overloaded on one side and the resistance value could not be measured. This is considered to be a break in the metal wiring. From this comparison, it was confirmed that in the double-sided conductive sheet, the influence of the bending deformation was large, and it was found that the single-sided two-layer structure of the present embodiment is resistant to deformation.

Second Embodiment Here, with respect to the conductive sheet of the first embodiment, the conductive sheet was manufactured by changing the thickness (film thickness) of the wiring, and the bending test was performed. The used substrate, the fluorine resin (CYTOP (registered trademark)), the metal ink (silver ink), and the photomask are the same as in the first embodiment. In the present embodiment, the thickness of the metal wiring is adjusted by applying a metal ink in an overlapping manner. Specifically, in the manufacturing process of each of the first and second metal wires, the combination of metal ink application and hot air drying was used as a single "application" to form metal wires by multiple applications. In the present embodiment, one application (film thickness 0.04 μm: first embodiment), two applications (film thickness 0.08 μm), five applications (film thickness 0.2 μm), eight applications (film thickness 0) .32 μm). A metal wiring was formed by application 16 times (film thickness 0.64 μm). In each example, the thicknesses of the first and second metal wires were the same. Moreover, the metal wiring of several film thickness was similarly formed also about the conductive sheet of the double-sided structure which is a comparative example. Then, as in the first embodiment, the bending test and the measurement of the resistance value were performed. The results are shown in Table 2.

In each of the embodiment and the comparative example, since the thickness increases and the cross-sectional area of the wiring increases, the resistance value decreases. In the comparative example, when the thickness is set to 0.08 μm or more, the disconnection occurring at 0.04 μm does not occur. However, in the comparative example, the increase in resistance value on the back side after the bending test is extremely large. On the other hand, in the case of the conductive sheet of the present embodiment, both the first and second metal wires maintain a stable resistance value. Thus, it was confirmed that the single-sided two-layer structure of the present embodiment is resistant to deformation even when the thickness of the metal wiring is changed.

Third Embodiment : In the present embodiment, a conductive sheet in which the line width of the metal wiring is changed is manufactured and a bending test is performed. The substrate used, the fluorocarbon resin (CYTOP (registered trademark)) and the metal ink (silver ink) are the same as in the first embodiment, and after the photomask is exposed using a photomask whose line width only has been changed, Silver wiring was formed with metal ink (silver ink). Specifically, photomasks having line widths of 1 μm, 2 μm (first embodiment) and 5 μm were used. As in the first embodiment, a conductive sheet having a single-sided two-layer structure and a double-sided structure which is a comparative example was manufactured, and a bending test and measurement of a resistance value were performed. The results are shown in Table 3.

From Table 3, even in the conductive sheets of the present embodiment and the comparative example, the resistance value of the metal wiring after the bending test tends to increase. However, in one metal wiring (second electrode layer) of the double-sided structure of the comparative example, the increase in resistance value was remarkable. That is, when the line width is 1 μm, the increase in the resistance value of the second electrode layer of this embodiment is 1.05 kΩ, but in the comparative example, a remarkable increase of 6.38 kΩ is observed. Also, this tendency was remarkable when the line width was small. Even if the line width was changed, it was found that the double-sided structure of the comparative example was weak to bending deformation, and the single-sided two-layer structure of the present invention was strong to bending deformation.

Fourth Embodiment In this embodiment, a conductive sheet is manufactured while changing the configuration (thickness) of the first electrode layer, the intermediate layer, and the second electrode layer. The manufacturing process of the conductive sheet was basically the same as that of the first embodiment, and the same substrate, metal ink and the like were used. The thickness was adjusted by changing the number of times of application of the precursor material of each layer.

Further, in the present embodiment, the same fluorocarbon resin (CYTOP (registered trademark)) as that of the first embodiment is used as the fluorocarbon resin to be the first and second underlayers, but some examples (No. 9) ), Another fluorocarbon resin (Algoflon (registered trademark) AD40) was used. However, the formation conditions of each underlayer were the same.

In the evaluation of the various conductive sheets manufactured in the present embodiment, it was determined whether the first and second metal wires were formed as designed. For each conductive sheet,
Ten measurement points were randomly determined from the first and second metal wires, and line widths at the measurement points were measured. At this time, when the error is 50% or less with respect to the design value of 2.0 μm (a line width of 1.5 to 2.5 μm), it is regarded as pass. Then, for ten measurement points, those that passed at 10 points were regarded as excellent “優良”, and those that passed at eight points were regarded as good “○”. Further, those having a score of 7 points or less, or those having observed even one disconnection were judged as “bad”. The evaluation results are shown in Table 4.

From Table 4, the electroconductive sheet manufactured by this embodiment showed a generally favorable evaluation result. However, if the second underlayer is too thin, a part of the metal wiring may be rejected (No. 5), so the thickness of the second underlayer should be 0.04 μm or more. Is preferable (No. 4). As to the first underlayer, a thin layer of 0.02 μm is sufficiently effective (NO. 2).

Further, the intermediate layer is not an essential component, and even if there is no intermediate layer, it can be coped with by adjusting the thickness of the second underlayer (No. 6). And when setting an intermediate | middle layer, thickness can be set in consideration of the structure of the 1st electrode layer under it (No. 7). However, when the thickness of the intermediate layer was excessively thick, disconnection was observed and it became unsuitable as a conductive sheet (No. 8). It was confirmed that, when setting the intermediate layer, it is necessary to make its thickness appropriate. Also, although the intermediate layer is not an essential component, when the fluorine resin used in the present embodiment and the acrylic resin used in the intermediate layer are compared, the acrylic resin used in the intermediate layer is less expensive. Application of layers is considered useful.

In the present embodiment, the conductive sheet No. 1 in which CYTOP (registered trademark) is applied to the underlayer, and No. 1 in which Algoflon (registered trademark) AD 40 is applied. We examined about nine conductive sheets. Here, CYTOP (registered trademark) has 6 carbon atoms, 10 fluorine atoms, and 3 oxygen atoms in its repeating unit. The ratio (F / C) of the number of fluorine atoms to the number of carbon atoms on the structural formula is 1.7. In addition, Algoflon (registered trademark) AD40 has, in the repeating unit, 6 carbon atoms, 10 fluorine atoms, and 1 oxygen atom. The ratio (F / C) of the number of fluorine atoms to the number of carbon atoms on the structural formula is 1.7. In the present embodiment, it was confirmed that good results were obtained no matter which fluorine resin was applied.

As described above, the conductive sheet according to the present invention is a sheet in which two electrode layers are formed in a two-layer structure on one side of a substrate. The present invention is resistant to bending with respect to a conventional double-sided conductive sheet, and can also cope with thinning of the conductive sheet. The conductive sheet of the present invention is capable of appropriately performing anti-reflection processing on metal wires while being provided with extremely fine metal wires. Therefore, this invention can also be made into a suitable transparent conductive sheet by making selection of a board | substrate appropriate. The present invention can be effectively applied as a component of a touch panel.

Claims (20)

1. A conductive sheet comprising a substrate and an electrode layer formed on one side of the substrate,
   The electrode layer includes a first electrode layer and a second electrode layer,
   A first electrode layer and a second electrode layer are laminated in this order on the substrate,
   The first electrode layer comprises a first underlayer made of a fluorocarbon resin and a first metal wiring formed on the surface of the first underlayer,
   The conductive sheet according to claim 1, wherein the second electrode layer comprises a second underlayer made of a fluorocarbon resin and a second metal wire formed on the surface of the second underlayer.
2. The fluorine resin constituting the first and second underlayers is a repeating unit containing carbon (C) and fluorine (F) and based on a fluorine-containing monomer, and the ratio of the number of fluorine atoms to the number of carbon atoms The conductive sheet according to claim 1, which is a resin comprising a polymer having at least one repeating unit having (F / C) of 1.0 or more.
3. The conductive sheet according to claim 2, wherein the fluorine resin constituting the first and second underlayers further contains at least one oxygen atom (O) in a repeating unit based on a fluorine-containing monomer constituting the polymer. .
4. The conductive sheet according to any one of claims 1 to 3, wherein the thickness of the first underlayer is 0.01 μm or more and 5 μm or less.
5. 5. The conductive sheet according to any one of claims 1 to 4, wherein the thickness of the second underlayer is 0.04 μm or more and 1 μm or less.
6. The conductive sheet according to any one of claims 1 to 5, wherein a distance between a bottom surface of the first metal wiring and a bottom surface of the second metal wiring is 1.2 μm or more and 4.5 μm or less.
7. The conductive sheet according to any one of claims 1 to 6, wherein the first and second metal wires are made of at least one of silver, gold, platinum, palladium, copper and nickel.
8. The conductive sheet according to any one of claims 1 to 7, further comprising at least one intermediate layer made of a dielectric or an insulator between the first electrode layer and the second electrode layer.
9. The conductive sheet according to claim 8, wherein the thickness of the intermediate layer is 1 μm to 3 μm in total.
10. The conductive sheet according to any one of claims 1 to 9, wherein the surface of the second electrode layer comprises at least one coating layer.
11. The conductive sheet according to claim 10, wherein the thickness of the coating layer is 1 μm to 3 μm in total.
12. The conductive sheet according to any one of claims 1 to 11, which has a total light transmittance of 85% or more based on JIS K7361-1.
13. A touch panel comprising the conductive sheet according to any one of claims 1 to 12.
14. A method of manufacturing a conductive sheet according to any one of claims 1 to 12,
    Forming a first electrode layer and a second electrode layer in this order on one side of the substrate;
    A method of producing a conductive sheet by forming the first and second electrode layers by a method including the following steps (a) to (c):
    (A) A step of applying a fluorine resin to a substrate to form an underlayer.
    (B) forming a functional group at a portion of the underlying layer where the metal wiring is formed.
    (C) A metal ink comprising a protective agent A comprising an amine compound and metal fine particles protected by a protective agent B comprising a fatty acid dispersed in a solvent is applied to the surface of the substrate, and the metal fine particles are applied to the underlayer. The process of forming metal wiring by fixing.
15. The process according to claim 14, wherein in the step of forming the functional group on the surface of the underlayer made of a fluorocarbon resin, energy of 1 mJ / cm ² or more and 4000 mJ / cm ² or less is applied to the portion of the underlayer for forming metal wiring. Sheet manufacturing method.
16. The method for producing a conductive base sheet according to claim 14 or 15, wherein at least one of a carboxy group, a hydroxy group and a carbonyl group is formed as a functional group.
17. Protecting agent A consisting of an amine compound of metal ink consists of at least one of amine compounds of 4 to 12 carbon atoms, and protecting agent B consisting of fatty acids consists of at least one fatty acid of 4 to 26 carbon atoms A method of producing a conductive base sheet according to any one of claims 14 to 16.
18. The metal particles are bonded to form a metal wiring by heating the substrate to 40 ° C. or more and 250 ° C. or less after fixing the metal particles to the underlayer in the step (c). Method of producing a conductive substrate.
19. The method for manufacturing a conductive substrate according to any one of claims 14 to 18, comprising the step of forming at least one intermediate layer after forming the first electrode layer and before forming the second electrode layer.
20. The method for producing a conductive substrate according to any one of claims 14 to 19, including the step of forming at least one coating layer after forming the second electrode layer.

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