JP5562283B2 - Transparent conductive material comprising transparent conductive film mainly composed of graphene and method for producing the same - Google Patents

Description

The present invention relates to a flexible two- dimensional transparent conductor and a three-dimensional transparent conductor provided with a transparent conductive film mainly composed of graphene, and a method for producing the same.

  In a communication device such as a mobile phone, an electronic information device, a liquid crystal display, a solar cell, and the like, a transparent conductor excellent in transparency and conductivity is required. Further, in recent years, with the reduction in weight and size, a flexible two-dimensional transparent conductor and a three-dimensional transparent conductor that can be bent are desired due to the demands of the design.

  Indium tin oxide (ITO) is mainly used for the transparent conductive material of the transparent conductive film. However, direct ITO patterning into a three-dimensional shape is technically difficult, and even if a three-dimensional shape is formed after the ITO pattern is formed into a two-dimensional shape, the ITO is brittle, the substrate is stretched, Since it does not follow shrinkage, bending, etc., the conductivity is lowered, and it is technically difficult to produce a three-dimensional shape having transparency and conductivity. In addition, since ITO contains indium which is a rare earth, there are problems in terms of resource depletion, stable supply, environmental load, and the like.

  For this reason, ITO alternative materials are being studied, and carbon nanotubes (CNT), metal nanowires, and the like are listed as candidates. Among these, CNT has characteristics of both mechanical strength and flexibility necessary for a transparent conductive film having a three-dimensional shape. However, in the case of using CNT, in order to obtain conductivity as a conductive material, it is necessary to form a three-dimensional network structure by bringing a plurality of CNTs serving as conductors into contact with each other at points in a binder for fixing CNT. is there. In order to form this network structure, for example, in the coating method, many steps such as selection and adjustment of a solvent and a dispersing agent are required to dissolve and disperse CNT in a solution (Patent Document 1).

  Another ITO alternative material is Graphene. Graphene is a two-dimensional material having a honeycomb structure in which carbon atoms are bonded to three adjacent carbon atoms. In the case of patterning graphene having mechanical strength and flexibility as in the case of CNT, a method of patterning by masking after film formation can be employed. This method does not need to go through complicated steps like the coating method, and is greatly different from CNT.

  In the method of forming a graphene film, a sheet-like Cu substrate (thickness 15 μm, 25 μm) as a catalyst is wound around a cylindrical reactor and formed on a Cu substrate by chemical vapor deposition (CVD) at 1000 ° C. After film formation, there is a method in which a roll-to-roll method is applied to a long substrate, and the Cu substrate is removed by etching (Non-Patent Document 1). However, in this method, since many steps are required, the generated graphene film is damaged such as wrinkles and tears, and there is a problem that the properties of graphene are deteriorated. Thus, as a result of intensive studies, the inventors have invented a transfer sheet in which graphene is generated on a metal thin film layer serving as a catalyst without going through a transfer process in which the graphene layer is damaged.

Republished 2006-132254 S. Bae et al. , Nature Nanotech. 5,574 (2010)

The present invention has been made in order to solve the above problems, and using a transfer sheet having graphene as a transparent conductive material, a transparent conductor having a flexible two- dimensional shape, a transparent conductor having a three-dimensional shape, and the production thereof In providing a method.

  In order to achieve the above object, as a result of intensive investigations, the inventor made a graphene-based transparent conductive material by using a transfer sheet mainly composed of graphene on a metal thin film by a simultaneous molding transfer method. A transparent conductor and a manufacturing method thereof can be provided.

  Means for solving the above problems in the present invention will be described below.

  A first aspect of the present invention is a transparent conductive material having a single transparent conductive portion mainly composed of graphene, and is formed on a transparent substrate having a two-dimensional shape and on any surface of the transparent substrate. And a transparent conductive portion comprising a transparent conductive layer mainly composed of graphene formed on the resin layer, and having a single transparent conductive film portion and having flexibility. It is a film.

According to a second aspect of the present invention, there is provided a transparent conductive material including two transparent conductive portions mainly composed of graphene, and a flexible first transparent substrate having a two-dimensional shape and any one of the first transparent substrates. A first transparent conductive portion comprising a first resin layer formed on the surface and a first transparent conductive layer mainly composed of graphene formed on the first resin layer; and a flexible two-dimensional shape A second transparent substrate; a second resin layer formed on any surface of the second transparent substrate; and a second transparent conductive layer mainly composed of graphene formed on the second resin layer. A second transparent conductive portion, wherein the first transparent conductive portion and the second transparent conductive portion are opposed to each other so as to be electrically insulated, and have a flexible two- dimensional shape. It is a transparent conductor.

  According to a third aspect of the present invention, there is provided a transparent conductive material including one transparent conductive portion mainly composed of graphene, a three-dimensional transparent substrate, and a resin layer formed on any surface of the transparent substrate. A transparent conductive film comprising a transparent conductive layer comprising a transparent conductive layer mainly composed of graphene formed on the resin layer, and having a three-dimensional shape having one transparent conductive part. is there.

  A fourth aspect of the present invention is a transparent conductive material including two transparent conductive parts mainly composed of graphene, and is formed on a surface of a three-dimensional first transparent substrate and the first transparent substrate. A first transparent conductive portion comprising a first resin layer, a first transparent conductive layer mainly composed of graphene formed on the first resin layer, a second transparent substrate having a three-dimensional shape, A second transparent conductive portion comprising a second resin layer formed on any surface of the two transparent substrates, and a second transparent conductive layer mainly composed of graphene formed on the second resin layer; A transparent conductive material characterized in that the first transparent electrode portion and the second transparent electrode portion are positioned so as to be electrically insulated and have a three-dimensional shape including two transparent conductive portions. .

  The fifth aspect of the present invention is a transparent conductive material in which an insulating layer is provided between the first transparent conductive portion and the second transparent conductive portion.

  According to a sixth aspect of the present invention, there is provided an insulating transparent resin and a plurality of conductive pressure-sensitive substances dispersed and contained in the transparent resin, disposed between the first transparent electrode portion and the second transparent electrode portion. When a force is applied to one surface of the transparent conductive material, a current flows between the pressure-sensitive substances in the pressure conductive layer by the applied force, so that the first transparent conductive layer and the opposing first transparent conductive layer It is a transparent conductive material characterized in that conduction is performed between two transparent conductive layers.

  The seventh aspect of the present invention is a transparent conductor including a routing circuit portion.

  According to an eighth aspect of the present invention, there is provided the transparent conductive material characterized in that the routing circuit portion is located around the transparent electrode portion.

  According to a ninth aspect of the present invention, a transfer sheet having a transparent conductive portion mainly composed of graphene is placed in an injection mold, and a molding resin is injected. Simultaneously with the solidification of the molding resin, a molding resin product is provided. A transparent process comprising a first step of integrally bonding a transfer sheet to one surface of a surface and removing a base sheet having releasability, and a second step of removing a metal thin film layer formed on the one surface In the method for producing a conductive material, a transparent conductive material comprising a single transparent electrode portion mainly composed of graphene and having flexibility.

  According to a tenth aspect of the present invention, a first transfer sheet having a first transparent conductive portion mainly composed of graphene is placed in an injection mold, a molding resin is injected, and the molding resin is solidified. At the same time, a first step of integrally bonding the first transfer sheet to the first one surface of the molding resin surface and removing the base sheet having releasability, and a first metal thin film layer formed on the first one surface A second transfer sheet having a second transparent conductive portion mainly composed of graphene and the second one surface of a flexible two-dimensional transparent substrate by heat and pressure. A third step of bonding and removing the base sheet having releasability; a fourth step of removing the second metal thin film layer formed on the second one surface; a first transparent conductive portion and a second transparent conductive layer; The first one surface and the second one surface are opposed so that the portion is electrically insulated In a method for producing a transparent conductive material comprising a fifth step of forming a resin layer or a pressure conductive layer between the first transparent conductive portion and the second conductive portion, and bonding with an adhesive It is a manufacturing method of a transparent conductor characterized by having two transparent conductive parts characterized by having a three-dimensional shape.

  According to an eleventh aspect of the present invention, there is provided a capacitive touch input device including a transparent conductive material, wherein the routing circuit portion is located around the transparent electrode portion.

  A twelfth aspect of the present invention is a resistive film type touch input device including a transparent conductor.

Since the transfer sheet used in the present invention is used for a transparent conductive film layer mainly composed of graphene having flexibility and mechanical strength, not only can it be formed on a flexible two- dimensional shape to be transferred, A transparent conductive layer can be transferred onto a three-dimensional transfer object. As a result, there is an effect that the use and function of the portable electronic device mounting the transparent conductive material is expanded.

  The transparent conductive material of the present invention is a method in which a patterned transparent conductive film layer is produced with a two-dimensional sheet-like transfer sheet, and is then integrated into a transfer object and simultaneously formed and removed to remove the metal thin film layer. Therefore, it has the effect of being excellent in mass productivity.

  In forming a transparent conductive film layer composed mainly of graphene, graphene is created on the metal thin film layer patterned on the transfer sheet by CVD, so patterning by irradiation with high energy light such as an electron beam is not required after film formation It is. Furthermore, the layer containing the transparent conductive film can be transferred simply by transferring the transfer sheet to a desired transfer target. Therefore, since graphene can be produced without applying a load more than necessary, a transparent conductor with good quality and mass productivity can be provided.

FIG. 1 shows a cross section of a transfer sheet used in the ninth embodiment of the present invention when a metal thin film layer is partially formed on the substrate sheet of the present invention. FIG. 2 shows a cross section of a transfer sheet used in the tenth embodiment of the present invention. FIG. 3 is a cross-sectional view showing the transfer sheet manufacturing method used in the tenth aspect of the present invention in the order of steps. FIG. 4 is a cross-sectional view showing the transfer sheet manufacturing method used in the tenth aspect of the present invention in the order of steps. FIG. 5: is sectional drawing which showed the manufacturing method of the transparent conductor of the 9th aspect of this invention in process order. FIG. 6: is sectional drawing which showed the manufacturing method of the transparent conductor of the 3rd aspect of this invention in process order. FIG. 7: is sectional drawing which showed the manufacturing method of the transparent conductor of the 10th aspect of this invention in process order.

  Hereinafter, a transfer sheet, a transparent conductor, and a manufacturing method thereof according to an embodiment of the present invention will be described in detail.

  The transfer sheet 1 in the present invention refers to a sheet on which a layer including the transparent conductive film layer 4 can be transferred to a transfer target 10 (including not only two dimensions but also three dimensions) by pressure heating or the like. The transfer sheet 1 of the present invention comprises a substrate sheet 7 having releasability, a metal thin film layer 3, a transparent conductive film layer 4, and an adhesive layer 5 (see FIG. 1). There is a metal thin film layer 3 formed in a desired pattern or formed on the entire surface on a substrate sheet 7 having releasability, and there is a transparent conductive film layer 4 along the metal thin film layer 3. An adhesive layer 5 is provided. The base sheet 7 having releasability preferably has a structure in which a release layer 6 is provided on the base sheet 2 (see FIG. 1). Details of the significance of providing the release layer will be described later.

  The transfer sheet 1 of the present invention can be divided into transparent conductive portions 8 and 10 and routing circuit portions 9 and 11 (see FIGS. 1 and 2). The transparent conductive portion 8 and the routing circuit portion 9 in the transfer sheet are transparent conductive materials produced after transfer. For example, in a touch panel, they correspond to a display display portion and a portion outside the display display, respectively. The difference between FIG. 1 and FIG. 2 is in the area where the routing circuit exists. That is, in FIG. 2, the routing circuit exists only in the routing circuit unit 11, but in FIG. 1, it exists not only in the routing circuit unit 9 but also in the transparent conductive unit 8 (not shown).

  In the case of forming the transparent conductive film layer 4 on the entire surface of the transfer sheet of the present invention, the metal thin film layer 3 is formed on the entire surface of the substrate sheet 7 having releasability by forming the metal thin film layer 3 by sputtering or the like. It is obtained by forming the transparent conductive film layer 4 on the top by a method such as CVD and forming the adhesive layer 5.

  When the transparent conductive film layer 4 is partially formed on the transfer sheet 1 of the present invention, the metal thin film layer 3 as a catalyst is formed on the base sheet 7 having releasability before the transparent conductive film layer 4 is formed. And patterning. Examples of a method for patterning the metal thin film layer 3 include a solvent-soluble mask layer peeling method or a resist peeling method. In the former solvent-soluble mask layer peeling method, the solvent-soluble mask layer 12 is formed by a printing method or the like and masked to form the metal thin film layer 3, and then the unnecessary metal thin film layer 3 is removed by a cleaning process or the like. This is a method of patterning the metal thin film layer 3. That is, the base sheet 7 having releasability has a structure in which a release layer 6 is formed on the base sheet 2 (see FIG. 3A), and does not require the transparent conductive film layer 4 on the release layer 6. A solvent-soluble mask layer 12 is formed on the portion by a gravure printing method or the like (see FIG. 3B). After the metal thin film layer 3 is formed on the entire surface including the solvent-soluble mask layer 8 by a sputtering method or the like (see FIG. 3C), an unnecessary metal thin film layer 3 is formed together with the solvent-soluble mask layer 12 in a solvent cleaning step. As a cleaning solvent, an aqueous solution or an alcohol is often used.

  In the latter resist stripping method, the metal thin film layer 3 is formed on the entire surface of the release layer 6, the resist layer 13 is formed on the portion where the metal thin film layer 3 is to be formed, and the metal thin film layer 3 is formed with an acid or alkali aqueous solution. In this method, after the resist is removed by etching, the resist layer 13 is peeled off with a solvent or the like and the metal thin film layer 3 is patterned. A metal thin film layer 3 is formed on the entire surface of the release layer 6 (see FIG. 4A) of the base sheet 7 having releasability by sputtering or the like (see FIG. 4B). A patterned resist layer 13 is formed on the portion where the transparent conductive film layer 4 is to be formed (see FIG. 4C). The metal thin film layer 3 where the resist layer 13 is not formed is etched away by dipping in an etching solution made of an acid or alkali aqueous solution (see FIG. 4D). Thereafter, the patterned metal thin film layer 3 is obtained by peeling and removing the resist layer 13 with a solvent or the like (see FIG. 4E). The solvent-soluble mask layer peeling method has the advantage of fewer steps than the resist peeling method, and the resist peeling method is easy to use photo or electron beam for resist patterning, so the solvent soluble mask layer peeling method There is an advantage that finer patterning is possible.

  Graphene is generated by CVD on the patterned metal thin film layer 3 obtained by the solvent-soluble mask layer peeling method or the resist peeling method, and the transparent conductive film layer 4 is obtained (FIG. 3 (e), FIG. 4 ( f)). Note that graphene is not generated in a portion where the metal thin film layer 3 is not provided. Finally, the transfer sheet is obtained by forming the adhesive layer 5 (see FIGS. 3 (f) and 4 (g)). Note that when the transfer target 10 is formed of a material that is easily bonded to the transparent conductive film layer 4, the adhesive layer 5 may be omitted.

  The transparent conductive material 21 in which one layer of the transparent conductive film layer 4 of the present invention is formed is performed by the following transfer and removal of the metal thin film layer using the above transfer sheet. First, transfer is described. If the shape of the transfer object is a flexible two-dimensional shape, roll transfer method, up-down transfer method, etc., if it is three-dimensional shape, in addition to roll transfer method, up-down transfer method, pad transfer method, vacuum transfer method Method and molding simultaneous transfer method. In the roll transfer method, there is a transfer machine provided with a cylindrical heat roll made of silicon rubber. The transfer sheet comes into contact with the transfer target and is pressed by the roll to remove the peelable substrate sheet. In the up-down transfer method, the heated flat rubber is pressed against the transfer material by the transfer sheet, and the base sheet having peelability is removed. In the pad transfer method, a pad having a shape corresponding to the shape of the transfer object is used. In the vacuum transfer method, a minute hole is provided in a mold corresponding to the shape of the transfer object, and the transfer sheet is brought into close contact with the shape of the mold in a state where the hole is decompressed and heated. The transferred material is adhered onto the transfer sheet, and the base sheet having releasability is removed. The transfer is performed under conditions of a temperature of 70 to 280 ° C. and a pressure of 40 to 180 kg / m 2. The selection of these transfer methods is determined by the shape of the transfer object so that heat and pressure are uniformly applied during transfer. Up-down transfer is effective for a transfer object having a substantially planar shape, and roll transfer is effective for a transfer object having a simple planar shape or a cross-section as shown in FIG. In the case of a complicated shape, pad transfer and vacuum transfer are effective.

  Furthermore, a vacuum forming method is effective for transferring to a three-dimensional shape. The transfer sheet 14 is placed on the movable mold 15 side of the injection mold so that its adhesive surface is on the fixed mold 16 side (see FIG. 5A). The transfer plate 17 placed between the movable mold 15 and the fixed mold 16 heats and softens the transfer sheet. At the same time, air is exhausted and sucked through a plurality of fine holes (vacuum holes 18) of the movable mold to move the movable mold and the transfer sheet. Reduce the pressure in the space formed by. As a result, the transfer sheet softened without the space becomes a three-dimensional shape along the movable mold (see FIG. 5B). Here, the movable shape corresponds to one shape of a desired transparent conductor. The resulting three-dimensional transfer sheet is transferred to a transfer medium by any of the transfer methods described above. For example, the transfer sheet having the three-dimensional shape is aligned with the transfer target (see FIG. 5C) and transferred by a roll transfer machine (see FIG. 5D).

  On the other hand, there is a transfer by a simultaneous molding transfer method which is excellent in mass productivity for performing molding simultaneously with transfer. Here, the simultaneous molding transfer method is a method in which a transfer sheet is closed with a mold and sandwiched, and a molten molding resin is injection-molded, and at the same time, a transparent conductive layer or the like on the transfer sheet is bonded to a resin molded product and simultaneously molded It refers to a method of transferring the functional layer (transparent conductive film layer or the like) and obtaining a molded resin product including the functional layer on the surface thereof. The transfer sheet 14 of the present invention obtained by the above method (the transparent conductive portion 8 also has a routing circuit) is transferred to the movable mold 15 side between the molds for injection molding (movable mold 15 and fixed mold 16). 14 adhesive layers 5 are placed so as to face the fixed mold 16 (see FIG. 6A). The mold is closed (see FIG. 6B). Here, the width, height, depth and shape of the space (molding space portion 21) formed by closing the movable die 15 and the fixed die 16 are the desired width, height, depth and shape of the transparent conductor, respectively. It corresponds to. In a state where the mold is closed, when the molten molding resin 22 is poured into the molding space 21 through the gate portion 23 and solidified, the transfer sheet 14 and the molding resin 22 are integrally bonded (see FIG. 6C). When the base sheet 7 having the peelability of the transfer sheet 14 is removed by opening the mold, the layer 24 including the transparent conductive film layer 4 is formed on the surface of the molded resin product (transparent conductive material) 25.

  When transferring to a more complicated shape, the extension of the transfer sheet cannot follow the shape of the transferred material, resulting in problems such as distortion and tearing of the transparent conductive film layer. In order to cope with this problem, a method is adopted in which a transfer sheet is formed in advance by a vacuum forming method and then transferred to a three-dimensional shape surface by a simultaneous forming transfer method. In the state where the three-dimensional transfer sheet is obtained in FIG. 5B, the heating plate 17 is removed, the mold is closed, and the molding resin 22 is injected into the molding space 21 to be integrated with the transfer sheet. A transparent conductive material can be obtained by opening and removing the base sheet having peelability.

  Next, the removal of the metal thin film layer will be described. The removal is performed by wet etching. As the wet etching method, there are a spray method in which an etching solution is sprayed in a mist, a dip method in which the etching solution is applied to the etching solution, and the like. For example, the metal thin film layer can be removed by immersing a transfer object having a surface including a transparent conductive film layer on the surface in an etching solution. And the transparent conductor in which one layer of transparent conductive layers was formed is obtained.

  The transparent conductive material in which two transparent conductive layers of the present invention are formed is a single layer of the transparent conductive layer using a transfer sheet having a routing circuit only around the transparent conductive portion 10 by any of the transfer methods described above. The formed transparent conductor is produced. On the other hand, a transfer sheet having a routing circuit around the transparent conductive portion is integrally bonded to a flexible transparent substrate (transfer target body 26) by pressure heating such as roll transfer (see FIG. 7A), and peelability is obtained. The base sheet 7 having a certain thickness is removed (see FIG. 7B), and the metal thin film layer 3 is removed by dipping in an etching solution, whereby a flexible two-dimensional transparent conductor 28 (see FIG. 7C). Is obtained. Finally, the above-described roll transfer method, up-down transfer method, pad transfer method, vacuum transfer method, etc. are used to bond the two-dimensional transparent conductor so as to face the transparent conductive layer of the three-dimensional transparent conductor. Can be obtained. FIG. 7D shows transfer by a roll transfer method.

  Here, in the adhesion of the three-dimensional transparent conductor and the two-dimensional transparent conductor, if a transparent and insulating adhesive is used, it can be used for a capacitive touch panel. By using the adhesive layer, in addition to maintaining the layer in contact with the adhesive layer, there is an effect of eliminating an appearance defect due to Newton's ring by not providing an air layer and an effect of a spacer for adjusting the distance between the transparent electrodes. On the other hand, if a transparent and pressure conductive adhesive is used, it can be used for a resistive film type touch panel. If a pressure conductive layer is provided between transparent electrodes with a transparent and pressure conductive adhesive, the effects of insulating by the spacer, interlayer adhesion, and appearance defects described above can be obtained.

  Further, the pressure conductive adhesive has the following functions for improving the reliability of the touch panel function. The pressure conductive layer in the present invention refers to a layer in which a plurality of transparent conductive substances are dispersed in an insulating transparent resin. In the state where there is no external pressure on the pressure conductive layer, it does not conduct and has insulation. When external pressure is applied, the resistance value decreases due to the contact of the conductive material or generation of a tunnel current due to the relative distance between the conductive materials approaching due to the shape change of the pressure conductive layer. Current flows in the pressure direction. In the touch panel, the pressing direction coincides with the direction between the transparent electrodes, so that the resistance value decreases and current flows, and position detection is possible. In addition, since the pressure is not applied to the transparent electrode plane direction, the insulating property is maintained, and there is no problem in position detection.

[Base sheet]
The material of the base sheet 2 in the present invention is not particularly limited as long as it is a material having heat resistance capable of withstanding the heat generated during the formation of the transparent conductive film layer 4 and the heat during transfer. Examples of such heat-resistant materials include polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyphenylene sulfide, polyethylene naphthalate, polyamideimide, polyarylate, high density polyolefin, Examples thereof include resins such as polycarbonate, polyethylene terephthalate, polyvinylidene fluoride, polyvinyl fluoride, polyvinylidene chloride, and liquid crystal polymer, and glass such as soda glass.

[Release layer]
The release layer refers to a layer remaining on the base sheet when it is transferred to a transfer object and the base sheet is peeled off. By having the release layer, the unevenness of the base sheet can be eliminated and the peeling weight (force required for peeling) can be adjusted. The material of the release layer 6 in the present invention has heat resistance that can withstand the heat generated during the formation of the transparent conductive film layer 4 and a predetermined release property. There is no particular limitation as long as it is a material that can be formed on a smooth layer having an arithmetic average roughness (Ra) of the surface of 0.1 nm ≦ Ra ≦ 20 nm. The arithmetic average roughness (Ra) is a numerical value measured with a measuring instrument (F3500D manufactured by Kosaka Laboratory Ltd.) according to Japanese Industrial Standard (JIS) B0601-1994. Examples of such a material having heat resistance and excellent smoothness include resins such as thermosetting acrylic, thermosetting polyester, thermosetting urethane, acrylic, epoxy, melamine, silicon, and fluorine. Examples of the method for forming the release layer 6 include coating by a roll coating method, a gravure printing method, a screen printing method, a die coating method, and the like. Note that the release layer 6 may be omitted if the base sheet 2 itself has releasability and the surface thereof has very high smoothness that falls within the range shown above. However, in many cases, the release layer 6 is required for the following reasons.

  Since the base sheet 2 serves as a base for forming each layer, the base sheet 2 needs to have a certain level of rigidity so as to be easily handled. Since the rigidity is proportional to the cube of the thickness, the thickness of the base sheet 2 is preferably at least 10 μm although it depends on the material. However, if the thickness of the base sheet 2 is thick, the numerical value of the unevenness on the surface of the base sheet 2 increases in correlation with it. Therefore, the base sheet 2 that is thicker and easier to handle is more difficult to obtain the effects of the present invention. However, if the release layer 6 is formed on the base sheet 2, the release layer 6 covers the base sheet 2 so as to fill the recesses on the surface of the base sheet 2. If it is formed to be as thin as possible with a surface roughness of 2 or more, the substrate sheet 7 has releasability that is very smooth and easy to handle.

[Metal thin film layer]
The metal thin film layer 3 of the present invention is a graphene catalyst which is a main component of the transparent conductive layer 4 and is formed on the substrate sheet 7 having the releasability by sputtering, vapor deposition, ion plating, or the like. The As the material, metals such as copper, nickel, ruthenium, iron, cobalt, iridium, platinum, and alloys thereof are used. As for the thickness of the metal thin film layer 3 of this invention, 0.01-1 micrometer is preferable. It is technically difficult to form a uniform film thinner than 0.01 μm, and when it is thicker than 1 μm, the smoothness of the substrate sheet 7 having releasability is not easily reflected, and the metal thin film layer 3 having large irregularities is likely to be formed. This is because a problem that it takes time for subsequent removal is likely to occur. Since the metal thin film layer 3 is much thinner than the metal plates (thickness 15 μm, 25 μm) used in the conventional graphene film production, the removal of the metal thin film layer 3 can be simplified in a short time, And since the smoothness of the layer under a metal thin film layer is reflected, the surface of a metal thin film layer becomes smooth and it can form a quality graphene film. When it is desired to partially form a metal thin film layer, it may be formed by a solvent-soluble mask layer peeling method or a resist peeling method.

[Transparent conductive film layer]
The transparent conductive film layer 4 of the present invention is composed of a layer including one or more graphene films and has conductivity. The term “transparent” as used herein means that the light transmittance of wavelengths in the visible region is 80% or more as a whole. The transparent conductive film layer 4 is formed only on the patterned metal thin film layer 3 by chemical vapor deposition (CVD) or the like. In particular, microwave plasma CVD is preferable in that damage to the base sheet 7 having releasability can be reduced. The source gas for microwave plasma CVD is a mixed gas of hydrocarbon and rare gas, and examples of the hydrocarbon include methane (CH4), ethane (C2H6), propane (C3H8), and acetylene (C2H2). Examples of the rare gas include helium (He), neon (Ne), and argon (Ar). In a state where the chamber of the CVD apparatus is decompressed, the total pressure of the mixed gas in the apparatus is set to 1 to 1000 Pa, preferably 10 to 400 Pa. A small amount of hydrogen gas may be mixed with this mixed gas. The temperature in the chamber of the CVD apparatus is 25 to 400 ° C, preferably 300 to 400 ° C. Since graphene can be formed using microwave plasma under relatively low pressure and low temperature conditions in this way, the energy density distribution of the generated plasma can be controlled, and the transparent conductive film layer 4 is formed. Damage to the base sheet 7 having releasability can be reduced. Furthermore, since the side opposite to the graphene film forming side of the substrate sheet 7 having releasability is cooled, damage can be reduced also by this. Thus, since the temperature is relatively low, a flexible film can be used as the base sheet 7 having releasability, and a roll-to-roll method can be adopted in forming the transparent conductive film layer 4. As a result, all the steps for producing the transfer sheet 1 of the present invention can be a roll-to-roll system, and the productivity of the transfer sheet 1 is dramatically improved.

[Solvent-soluble mask layer]
Examples of the material of the solvent-soluble mask layer 8 of the present invention include polyvinyl alcohol (PVA) and water-soluble acrylic resin. Examples of the solvent include an aqueous solution and an alcohol solution. Examples of the forming method include printing methods such as offset printing, screen printing, gravure printing, inkjet printing, and relief printing. It is more preferable to use a photoresist material that is soluble in the solvent. This is because the patterning can be formed by photolithography, so that a finer fine pattern can be formed.

[Resist layer]
The material of the resist layer 9 of the present invention can be formed of various resins such as acrylic and vinyl, and is not particularly limited. However, for forming a fine pattern, a resin that can be used as a photoresist is preferable, and examples thereof include novolak resin. The resist layer 9 is formed by first forming the entire surface by a printing method such as screen printing, gravure printing, ink jet printing, letterpress printing or the like, and bonding a resist film by heating and pressing. Next, the resist layer 9 is patterned after an exposure process in which light is irradiated and the exposed part is reactively cured, and then a development process in which the part not irradiated with light is removed. Then, after the etching of the three metal thin films not covered with the resist layer 9, the resist 9 layer which is irradiated with light in the exposure process and which is reactively cured is peeled off. The resist layer 9 is of a negative type (when exposed to a developer, its solubility in the developer is lowered and the exposed part remains after development). The solubility may be increased and the exposed portion may be removed after development).

[Adhesive layer]
The adhesive layer 5 of the present invention is made of acrylic or vinyl and has an insulating property. The insulating property here refers to, for example, a degree that does not cause a short circuit that causes malfunction of position detection in the input operation when the transparent conductor 11 is used as a touch panel for the transparent conductor 11 manufactured according to the present invention. It means the above insulation. The adhesive layer 5 is a layer that serves to adhere the transfer sheet 1 and the transfer target 10.

[Transfer]
The transfer target 10 is not particularly limited as long as it is transparent, does not have electrical conductivity, and has a certain degree of hardness, and may be a molded product having a three-dimensional shape in addition to a film shape. Examples of the material of the transfer target 10 include polyethylene terephthalate (PET), polyethylene, polypropylene, polystyrene, polyester, polycarbonate (PC), polyvinyl chloride, and acrylic. The thickness of the film-shaped transfer target 10 is preferably 30 to 200 μm.

[Transparent conductor]
In the present invention, the transparent conductor 11 is transparent and has conductivity. The transparent conductor is obtained by transferring the transparent conductor to the transfer target 10 using the transfer sheet 1 of the present invention and removing the metal thin film layer 3.

[Pressure conductive layer]
The pressure conductive layer is made of a resin and a conductive material. The resin is not particularly limited as long as it is transparent and insulating. For example, there are acrylic type and vinyl type. The conductive substance is not particularly limited as long as it has transparency, conductivity, and low visibility. The size is more preferable if it is equal to or smaller than the wavelength in the visible light region. The material is a metal oxide such as gold, silver, copper, aluminum, or an alloy thereof, ITO, zinc oxide (ZnO 2), or the like.

[Etching solution]
The etching solution is used for etching for removing the metal thin film layer. The metal thin film layer has a role as a catalyst in generating graphene, which is a main component of the transparent conductive film layer, and specifically, copper, nickel, ruthenium, iron, cobalt, iridium, platinum, and the like. Regarding the pH and composition of the etching solution, basically, a potential-pH diagram (metal-water system) may be referred to in relation to the metal used in the metal thin film layer. Other than the invariant region where the metal exists stably without causing a chemical reaction, and the passive region where a chemical reaction occurs at an initial stage under a specific potential-pH condition and a chemically inert chemical species is generated under the condition, The etching solution is selected so that the pH and potential of the corrosion region where the metal corrodes and the metal ions or metal compound ions exist stably are obtained. For example, the corrosion area of nickel is −0.4V ≦ potential ≦ + 0.4V and pH ≦ 6, or + 0.4V <potential ≦ + 1.5V and pH ≦ 0, and the copper corrosion area is potential ≧ + 0.2V. Thus, pH ≦ 7 or pH ≧ 11. It is adjusted by an oxidizing agent such as hydrogen peroxide, potassium permanganate, and ammonium persulfide, or a combination of the oxidizing agent and an acid such as sulfuric acid. Furthermore, it is more preferable that hydrogen generation does not occur. If the potential is higher than 0.00V which is the standard electrode potential E (vs SHE) of hydrogen, hydrogen is not generated. In this respect, E of copper is +0.34 V, which is larger than E = 0.00 V (hydrogen) of hydrogen, and hydrogen is not generated in the corrosion region. In addition, it is more preferred that no oxygen is present. This is because if oxygen is present, OH- is generated due to the reaction with water and the pH value increases, so that it may not belong to an appropriate pH range. In addition, conditions such as the immersion time of the etching solution and the immersion temperature are adjusted by the thickness and area of the metal thin film layer.

[Molded resin]
The molding resin is not particularly limited as long as it is a resin that is in a dissolved state at a high temperature. Polyethylene, acrylic resin, polystyrene resin, polyacrylonitrile styrene resin, polyester, polycarbonate, and the like can be used.

Example 1
A release layer 6 made of a fluororesin is formed on a base sheet 2 made of a polyimide film having a thickness of 30 μm (arithmetic average roughness (Ra) = 0.1 nm after formation), and the release layer 6 is formed on the release layer 6. A solvent-soluble mask layer 8 made of polyvinyl alcohol resin was formed by an offset printing method, and after drying, a metal thin film layer 3 (Cu layer having a thickness of 300 mm) was formed on the entire surface by a sputtering method. Then, the metal thin film layer 3 patterned by removing the metal thin film layer 4 of the location formed on it with the solvent soluble mask layer 8 by water washing was formed. Next, the sheet is introduced into a chamber filled with a source gas composed of methane and argon (partial pressure ratio methane: argon = 1: 1), and graphene is mainly formed by microwave plasma CVD at 380 ° C. for 40 seconds. A transparent conductive film layer 4 as a component was formed. The transparent conductive film layer 4 was patterned, and an adhesive layer 5 was formed on the entire surface thereof to produce a transfer sheet 1.
Example 2
The transfer sheet obtained in Example 1 was transferred to a PET film and immersed in a hydrogen peroxide-sulfuric acid based etching solution to prepare a two-dimensional transparent conductor. Another transfer sheet obtained in Example 1 is transferred by molding and simultaneously transferring the layer including the transparent conductive layer on the outer surface of the bowl using polystyrene resin, and immersed in a hydrogen peroxide-sulfuric acid based etching solution. The metal thin film layer was removed. The obtained two-dimensional transparent conductor was attached to the three-dimensional transparent conductor with an adhesive serving as a pressure conductive layer so that the transparent conductive layers face each other.

  A touch panel was produced from the obtained transparent conductor. A good operation function was obtained.

1 Transfer sheet
2 Base sheet
3 Metal thin film layer
4 Transparent conductive layer
5 Adhesive layer
6 Release layer
7 Substrate sheet with releasability
8 Transparent conductive part
9 Routing circuit
10 Transparent conductive part
11 Routing circuit
12 Solvent-soluble mask layer
13 resist layer
14 Transfer sheet
15 Moving parts
16 Fixed part
17 Heating plate
18 Vacuum hole
19 Transferee
20 roll transfer machine
21 Molding space
22 Molding resin
23 Gate
24 Layer including transparent conductive layer
25 Molded resin products (transparent conductor)
26 Transferee
27 Release surface
28 Transparent conductor
29 Transfer roll

Claims (9)

In a transparent conductive material having one transparent conductive part mainly composed of graphene,
The transparent conductive part is
A transparent substrate;
A resin layer formed on any surface of the transparent substrate;
A transparent conductive layer mainly composed of graphene formed on the resin layer;
With
A transparent conductive material, wherein a surface of a transparent substrate on which the resin layer is formed has a three-dimensional shape. In a transparent conductive material comprising a transparent conductive part composed mainly of graphene and comprising a first transparent conductive part and a second transparent conductive part,
The first transparent conductive part is
A flexible first transparent substrate having a two-dimensional shape;
A first resin layer formed on any surface of the first transparent substrate;
A first transparent conductive portion comprising a first transparent conductive layer mainly composed of graphene formed on the first resin layer;
With
The second transparent conductive part is
A flexible second transparent substrate having a two-dimensional shape;
A second resin layer formed on any surface of the second transparent substrate;
A second transparent conductive portion comprising a second transparent conductive layer mainly composed of graphene formed on the second resin layer;
With
The first transparent conductive part and the second transparent conductive part are opposed to each other so as to be electrically insulated, and have a flexible two-dimensional shape. In a transparent conductive material comprising a transparent conductive part composed mainly of graphene and comprising a first transparent conductive part and a second transparent conductive part,
The first transparent conductive part is
A first transparent substrate having a three-dimensional shape;
A first resin layer formed on any surface of the first transparent substrate;
A first transparent conductive layer mainly composed of graphene formed on the first resin layer;
With
The second transparent conductive part is
A second transparent substrate having a three-dimensional shape;
A second resin layer formed on any surface of the second transparent substrate;
A second transparent conductive layer mainly composed of graphene formed on the second resin layer;
With
The first transparent conductive portion and the second transparent conductive portion are positioned to face each other so as to be electrically insulated, and have a three-dimensional shape. The transparent conductor according to claim 2 or 3, wherein an insulating layer is provided between the first transparent conductive portion and the second transparent conductive portion. A pressure conductive layer disposed between the first transparent conductive portion and the second transparent conductive portion;
The pressure conductive layer is
When having an insulating transparent resin and a plurality of conductive pressure-sensitive substances dispersed and contained in the transparent resin, a force acts on at least one surface of the first transparent conductive portion or the second transparent conductive portion. The continuity is established between the first transparent conductive layer and the second transparent conductive layer by causing a current to flow between the pressure sensitive substances by an acting force. 4. The transparent conductor according to any one of 3. The transparent conductor according to claim 1, comprising a routing circuit part. The transparent conductor according to claim 6, wherein the routing circuit portion is located around the transparent conductive portion. A capacitive touch input device comprising the transparent conductor according to claim 1. A resistive film type touch input device comprising the transparent conductor according to claim 1.

Images