JP5519497B2 - Touch panel - Google Patents

Description

  The present invention relates to a touch panel using an electrode substrate having a conductive layer configured using entangled single-walled carbon nanotubes (but not using a binder resin).

  A touch panel is used for the display. That is, a transparent (light transmissive) touch panel (input device) is disposed on a display such as a liquid crystal screen. When a touch panel provided on the front surface of the display is touched, information is input. As this type of touch panel, for example, a touch panel having a structure in which the transparent electrode layers of two transparent electrode substrates are arranged to face each other (so-called resistance film type touch panel) is known.

  This resistive touch panel is often used for mobile devices (for example, mobile phones and mobile game machines). These portable devices have a small screen. And since the screen is small, it is designed so that it can be effectively used up to the edge of the screen. For this reason, the user often presses the screen edge.

  The material of the transparent electrode currently utilized is many ceramics as represented by the oxide (ITO) of indium and tin. For this reason, flexibility is bad.

  By the way, as described above, when the end of the screen is pressed, the pressed electrode substrate is locally bent. For this reason, there is a problem that the electrode substrate is damaged.

  In addition to the resistive touch panel, a so-called capacitive touch panel is known as a touch panel. This type of touch panel also has a conductive layer provided on a transparent substrate. Again, indium and tin oxide (ITO) is used.

  In a capacitive touch panel, there are few problems when glass is used for the substrate. However, when a resin substrate is used as the substrate, the surface hardness of the substrate is low, so that the durability is lowered. For this reason, there is a problem that the electrode substrate is damaged.

  For example, Japanese Patent Application Laid-Open No. 2004-202948 is known as a technique for an electrode substrate of a touch panel. That is, it comprises a base material layer made of a transparent resin and a conductive layer laminated on the base material layer, the conductive layer is disposed facing the substrate side conductive layer, and is brought into an energized state in contact with the substrate side conductive layer. A sheet-like resin laminate for a touch panel, wherein the conductive layer is a transparent matrix resin and carbon nanowires (for example, single-walled carbon nanotubes (for example, SWCNT manufactured by Hyperion), multi-walled carbon nanotubes (for example, Hyperion) MWCNT), vapor-grown carbon nanofibers (for example, VGCF manufactured by Showa Denko KK), etc., preferably a resin composition in which multi-walled carbon nanotubes or vapor-grown carbon nanofibers) are dispersed. A sheet-like resin laminate for touch panels has been proposed. In addition, a sheet-like resin laminate for a touch panel including a base material layer made of a transparent resin and a conductive layer laminated on the base material layer is interposed via a spacer in a state where the conductive layer faces the conductive layer on the substrate side. A touch panel disposed on the upper side of the substrate at a predetermined interval, wherein the conductive layer of the sheet-like resin laminate for touch panel is made of a resin composition in which carbon nanowires are dispersed in a transparent matrix resin. A characteristic touch panel has been proposed.

According to this proposed technique, an electrode substrate (a sheet-like resin laminate for a touch panel) rich in transparency, conductivity, and flexibility can be obtained. And it is said that it is suitable for touch panels.
JP 2004-202948 A

  However, according to the inventor's research, it has been found that the proposed technique, that is, a touch panel using an electrode substrate in which carbon nanowires are dispersed in a matrix resin, is inferior in performance. As a result of earnestly examining the cause of this performance failure, the proposed technique has a high contact resistance (high surface resistance) between carbon nanowires because the matrix resin is contained in the conductive layer. I came to realize that. And since resistance was high, it came to realize that the touch panel had malfunctioning.

  By the way, transparent conductive films are known. This type of film has a transparent conductive layer formed on an insulating substrate by a dry method such as PVD or CVD or a wet method such as coating. In the wet method, a conductive coating composition containing a conductive powder and a binder is prepared. This wet method has a simpler apparatus and higher productivity than the dry method. Furthermore, it can be easily applied to continuous or large substrates. For these reasons, a technique of a transparent conductive film has been proposed (for example, JP-A-2005-255985). That is, in Japanese Patent Application Laid-Open No. 2005-255985, the presence of carbon nanotubes reduces the production cost of conventional materials that do not contain carbon nanotubes, and improves the transparency and conductivity of the produced carbon nanotube-containing coating film. In order to improve the carbon nanotube, the carbon nanotube has a three-dimensional network structure, and the carbon nanotube is exposed on the surface of the carbon nanotube-containing coating film by infiltrating a dispersion containing resin into the carbon nanotube. Containing coating films have been proposed. For example, in the carbon nanotube-containing coating film applied on a substrate, the carbon nanotube-containing coating film has a three-dimensional network structure and is exposed on the surface of the carbon nanotube-containing coating film. A carbon nanotube-containing coating film characterized by the above has been proposed.

  However, Japanese Patent Application Laid-Open No. 2005-255985 does not mention any word about the touch panel to be provided by the present invention. Even the wording of the touch panel and the word reminiscent of the touch panel cannot be described in Japanese Patent Laid-Open No. 2005-255985.

  By the way, since Unexamined-Japanese-Patent No. 2005-255985 has proposed the transparent conductive film, the touch panel was made as a trial based on the technique as described in the Example of the said gazette.

  However, this prototype touch panel cannot perform as a touch panel. In other words, it was not something that could be commercialized.

  Therefore, the first problem to be solved by the present invention is to provide a touch panel that is not easily damaged even when bent so that the radius of curvature is small and has high mechanical durability.

  The second problem to be solved by the present invention is to provide a touch panel with low surface resistance and excellent operability.

The above issues are
A touch panel having an electrode substrate,
The electrode substrate is
A substrate,
A conductive layer provided on the substrate;
The conductive layer is
Having entangled single-walled carbon nanotubes,
It is solved by a touch panel characterized by having no binder resin.

  The touch panel is preferably a single-walled carbon nanotube obtained by an arc discharge method.

  A touch panel in which the conductive layer further contains fullerene is particularly preferable.

  A touch panel in which the fullerene is a fullerene hydroxide is particularly preferable.

  Further, a touch panel using an electrode substrate in which a protective layer is provided on the conductive layer is particularly preferable.

  A touch panel using an electrode substrate having an anti-Newton layer is particularly preferable.

  The touch panel of the present invention is, for example, a capacitive touch panel. Or it is a resistive film type touch panel. Two electrode substrates are used in this resistive film type touch panel. The two electrode substrates may be the electrode substrates. Alternatively, one of the two electrode substrates may be the electrode substrate.

  The conductive layer of the present invention has entangled single-walled carbon nanotubes. However, it does not have a binder resin. For this reason, even if the touch panel of the present invention is greatly bent, it is difficult to break, and the durability of the touch panel is high. Moreover, since the conductive layer contains no binder resin, the surface resistance of the touch panel is small. Therefore, the operability of the touch panel is excellent.

  If the conductive layer contains fullerene, especially hydroxylated fullerene, the touch panel was excellent in heat resistance.

Schematic side view of electrode substrate Electrode diagram of resistive touch panel (top view) Electrode diagram of resistive touch panel (side view) Resistive touch panel configuration (top view) Resistive touch panel configuration (side view) Configuration diagram of capacitive touch panel

DESCRIPTION OF SYMBOLS 1 Electrode substrate 2 Counter electrode 3 Upper counter electrode 4 Upper electrode substrate 5 Lower counter electrode 6 Adhesive tape 7 Lower electrode substrate 11 Substrate 12 Conductive layer 13 Protective layer

  The present invention is a touch panel. For example, a capacitive touch panel. Or it is a resistive film type touch panel. This resistive film type touch panel has a structure in which the conductive layers in the electrode substrate are arranged so as to face each other. That is, the two electrode substrates are arranged to face each other so that there is a gap between them. Of the two electrode substrates, one electrode substrate may be an electrode substrate having the structure of the present invention. Of course, the two electrode substrates may be electrode substrates having the structure of the present invention. The greatest feature of the present invention is the electrode substrate constituting the touch panel. This electrode substrate has a conductive layer (transparent conductive layer) 12 provided on a substrate (transparent substrate) 11 as shown in FIG. The conductive layer 12 is configured without using a binder resin. In order to make the binder resin unnecessary, single-walled carbon nanotubes constituting the conductive layer have a structure in which the single-walled carbon nanotubes are intertwined with each other. As a result, the single-walled carbon nanotubes are in direct contact with each other. Therefore, since there is no intervening insulator, the conductivity is good. In addition, since the single-walled carbon nanotubes are entangled with each other, no binder resin is required for the conductive layer. If the surface of the conductive layer is observed with a scanning electron microscope, it can be confirmed / determined whether the single-walled carbon nanotubes are intertwined.

  The conductive layer 12 may be a conductive layer composed only of entangled single-walled carbon nanotubes. However, it is particularly preferable that the conductive layer 12 has fullerene (in the present specification, “fullerene” includes “fullerene analog”, and the same shall apply hereinafter). Especially, it is a case where the conductive layer 12 has a fullerene hydroxide. That is, heat resistance was improved by including fullerene, particularly, fullerene hydroxide. Also, the conductivity was excellent.

  The fullerene may be any fullerene. For example, C60, C70, C76, C78, C82, C84, C90, C96 etc. are mentioned. Of course, a mixture of plural kinds of fullerenes may be used. C60 is particularly preferable from the viewpoint of dispersion performance. Furthermore, C60 is easy to obtain. Further, not only C60 but also a mixture of C60 and another kind of fullerene (for example, C70) may be used. Moreover, the metal atom may be included in the fullerene. Examples of the fullerene analog include those containing a functional group (for example, a functional group such as OH group, epoxy group, ester group, amide group, sulfonyl group, ether group). Moreover, what has phenyl-C61-propyl acid alkyl ester and phenyl-C61-butyric acid alkyl ester is also mentioned. In addition, hydrogenated fullerene is also included. Among them, fullerene having an OH group (hydroxyl group) (fullerene hydroxide) is preferable. This is because the dispersibility when coating single-walled carbon nanotubes as a dispersion was high. In addition, when there is little quantity of a hydroxyl group, the dispersibility improvement degree of a single-walled carbon nanotube will fall. On the other hand, if too much, synthesis is difficult. Therefore, the amount of OH groups is preferably 5 to 30 per molecule of fullerene. In particular, 8 to 15 are preferable.

  When there is too much addition amount (content) of fullerene, electroconductivity will fall. Conversely, if the amount is too small, the effect is poor. Therefore, the amount of fullerene is preferably 10 to 1000 parts by mass (particularly 20 parts by mass or more and 100 parts by mass or less) with respect to 100 parts by mass of the single-walled carbon nanotube.

  The single-walled carbon nanotube used in the present invention may be a single-walled carbon nanotube obtained by a known production method. For example, what was obtained by manufacturing methods, such as an arc discharge method, a chemical vapor deposition method, and a laser evaporation method, can be used. However, single-walled carbon nanotubes obtained by a production method using arc discharge are preferable from the viewpoint of crystallinity. And this thing is also easily available.

  The single-walled carbon nanotube is preferably a single-walled carbon nanotube subjected to acid treatment. Here, the acid treatment is performed by immersing single-walled carbon nanotubes in an acidic liquid. A technique called spraying may be employed instead of immersion. Various kinds of acidic liquids are used. For example, an inorganic acid or an organic acid is used. However, inorganic acids are preferred. For example, nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or a mixture thereof can be used. Among these, acid treatment using nitric acid or a mixed acid of nitric acid and sulfuric acid is preferable. Preferable acid treatment conditions are conditions in which the reaction is performed at a temperature of 80 ° C. to 100 ° C. for 1 day to 7 days. By this acid treatment, when single-walled carbon nanotubes and carbon microparticles are physically bonded via amorphous carbon, the amorphous carbon is decomposed and separated from each other, or the metal used when producing single-walled carbon nanotubes The fine particles of the catalyst will be decomposed. Therefore, in the present invention, acid treatment of single-walled carbon nanotubes is a very important requirement. For example, the conductivity is improved as compared with the case where acid treatment is not performed.

  The single-walled carbon nanotube is preferably a single-walled carbon nanotube from which impurities are removed by filtration and the purity is improved. This is because a decrease in conductivity and a decrease in light transmittance due to impurities are prevented. Various methods are employed for filtration. For example, suction filtration, pressure filtration, cross flow filtration and the like are used. Among these, from the viewpoint of scale-up, it is preferable to employ cross flow filtration using a hollow fiber membrane.

  The electrode substrate of the touch panel of the present invention preferably has a protective layer 13 on the conductive layer 12 made of single-walled carbon nanotubes. There is no particular limitation on the material used for the protective layer 13. For example, a thermoplastic resin such as a polyester resin, a cellulose resin, a polyvinyl alcohol resin, a vinyl resin, a cycloolefin resin, a polycarbonate resin, an acrylic resin, or an ABS resin is used. Moreover, well-known coating materials, such as a photocurable resin and a thermosetting resin, can also be used. However, the material of the protective layer is preferably the same (same system) material as the substrate from the viewpoint of adhesion. For example, when the substrate 11 is a polyester resin, the protective layer 13 is also preferably a polyester resin. In addition, when the film thickness of the protective layer 13 is too thick, the contact resistance of a transparent conductive layer will become large. On the contrary, if the thickness of the protective layer 13 is too thin, the effect as the protective layer cannot be obtained. Therefore, the thickness of the protective layer 13 is preferably 1 nm to 1 μm. In particular, 10 nm or more is preferable. Moreover, 100 nm or less is preferable.

  In the resistive film type touch panel of the present invention, two electrode substrates are required. One is an electrode substrate on the touch surface side called an upper electrode. The other is an electrode substrate (referred to as a lower substrate) disposed on the liquid crystal display side. In the capacitive touch panel, one electrode substrate may be used. A glass plate is generally used as the transparent substrate 11 of the electrode substrate. However, the transparent substrate 11 may be a resin plate, a resin sheet, or a resin film. A shield layer for noise removal may be provided on the surface opposite to the conductive layer 12. The electrode substrate is preferably in the form of a sheet or film having a total light transmittance of 80% to 100%. That is, a flexible transparent substrate is preferable. There are no particular restrictions on the material of the transparent substrate. For example, in addition to ceramics such as glass, thermoplastic resins such as polyester resin, cellulose resin, polyvinyl alcohol resin, vinyl chloride resin, cycloolefin resin, polycarbonate resin, acrylic resin, ABS resin, or photocurable resin Alternatively, a thermosetting resin or the like is used. The thickness of the transparent substrate 11 depends on the application. When a sheet shape is required, it is about 500 μm to 10 mm. When a film shape is required, it is about 10 μm to 500 μm.

  In the resistive touch panel, both the upper substrate and the lower substrate may be in the form of a sheet or film. One may be a sheet and the other may be a film. The conductive layers of both electrode substrates may be conductive layers made of single-walled carbon nanotubes. Only the conductive layer of one electrode substrate may be a conductive layer made of single-walled carbon nanotubes. This is because an electrode substrate made of single-walled carbon nanotubes has a low contact resistance with a ceramic conductive layer such as indium tin oxide. Therefore, even if the conductive layer of one electrode substrate is a ceramic conductive layer, good operability as a touch panel can be secured.

  The electrode substrate is preferably a substrate with fine irregularities and subjected to so-called anti-Newton treatment. The electrode substrate used for the resistive touch panel is preferably a substrate that has been subjected to anti-Newtonian treatment with fine irregularities on one or both of the upper substrate and the lower substrate. The upper substrate may be a substrate on which one or both sides of the substrate are subjected to a hard coat treatment for protecting the substrate, an antireflection treatment for improving visibility, and / or an anti-fingerprint treatment. The lower substrate may be one in which a conductive layer is laminated on the outermost substrate of the liquid crystal display.

  The electrode substrate preferably has a total light transmittance of 60% or more and 100% or less. The surface resistance value is preferably 100Ω / □ or more and 50000Ω / □ or less. This is because the visibility decreases when the total light transmittance is too low. By the way, the conductive layer comprised of single-walled carbon nanotubes has a trade-off relationship between the total light transmittance and the surface resistance value. Accordingly, the surface resistivity is preferably as high as the touch panel operates. Here, the total light transmittance is the total light transmittance including not only the conductive film containing single-walled carbon nanotubes but also the transparent substrate. In the resistive touch panel, a transparent conductive film having a total light transmittance of 70% or more and a surface resistance value of 100Ω / □ to 5000Ω / □ is preferable. In the capacitive touch panel, a transparent conductive film having a total light transmittance of 60% or more and a surface resistance value of 100Ω / □ to 1000Ω / □ is preferable.

  In the resistive touch panel of the present invention, it is preferable that dot printing is performed on any one of the conductive layers of the upper electrode and the lower electrode. This prevents erroneous contact between the conductive layers.

The resistive film type touch panel of the present invention can be manufactured by the following steps (preferably in the order of step 1 to step 7).
Step 1: Step of obtaining crude carbon nanotube Step 2: Step of acid treatment of crude carbon nanotube Step 3: Step of filtering single-walled carbon nanotube obtained in Step 2 Step 4: Single-walled carbon nanotube, fullerene, and solvent Is a process in which ultrasonic irradiation is performed (mixing / dispersing process)
Step 5: Step of applying the single-walled carbon nanotube dispersion obtained in Step 4 on the substrate Step 6: Step of forming wiring on the electrode substrate obtained in Step 5 Step 7: Obtained electrode substrate Where the layers are bonded so that the conductive layers are in contact with each other

Hereinafter, each process will be described in more detail.
[Step 1]
A known method can be adopted for step 1. For example, any manufacturing method such as an arc discharge method, a chemical vapor phase method, or a laser evaporation method may be used. However, the production method by the arc discharge method is most preferable from the viewpoint of the crystallinity of carbon nanotubes and the availability.

[Step 2]
Step 2 is a step in which single-walled carbon nanotubes are heated in an acidic liquid. There are no particular restrictions on acidic liquids. However, it is preferable to use inorganic acids such as nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof. In particular, nitric acid or a mixed acid of nitric acid and sulfuric acid is preferably used for the acid treatment before the alkali treatment. It is preferable to make it react with such an acid at the temperature of 80 to 100 degreeC over 1 day-7 days.

[Step 3]
Step 3 is a step in which impurities such as carbon particles are removed. In the carbon nanotube solution that has been subjected to the acid treatment, impurity particles having a diameter of about 20 nm and carbon nanotube bundles are dispersed (or precipitated) in the solution in a separated state. For this reason, the impurities are removed by filtration using a filter having a pore size larger than the impurities and smaller than the bundle of carbon nanotubes. Various filtration methods can be employed as the filtration method. For example, suction filtration, pressure filtration, cross flow filtration, or the like can be used. Among these, from the viewpoint of scale-up, it is preferable to employ cross flow filtration using a hollow fiber membrane.

[Step 4]
Step 4 is a step of producing a dispersion of single-walled carbon nanotubes. The ratio of the single-walled carbon nanotube to the fullerene is preferably 10 to 1000 parts by weight of fullerene with respect to 100 parts by weight of the single-walled carbon nanotube. The fullerene concentration is preferably 1 to 100,000 ppm. The fullerene is particularly preferably a fullerene having an OH group. Various methods can be employed for the irradiation of ultrasonic waves. For example, a bath type ultrasonic irradiator or a chip type ultrasonic irradiator can be used. From the viewpoint of processing in a short time, it is preferable to use a chip-type ultrasonic irradiator.
As the solvent, a solvent used in general paints is used. However, a solvent having a boiling point of 200 ° C. or lower (preferably lower limit is 25 ° C., further 30 ° C.) is preferable. The low boiling point solvent is preferred because it is easy to dry after coating. Specifically, water, alcohol (for example, alcohol such as methanol, ethanol, normal propanol, and isopropanol (particularly, alcohol having 7 or less carbon atoms, particularly aliphatic alcohol)), or a mixture thereof is preferable. It is done. This is because the hydroxyl group-containing fullerene has a high solubility, so that a single-walled carbon nanotube dispersion with a higher concentration can be obtained. In addition, ketone compounds (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ester compounds (eg, methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, methoxyethyl acetate, etc.), ether compounds ( For example, diethyl ether, ethylene glycol dimethyl ether, ethyl cellosolve, butyl cellosolve, phenyl cellosolve, dioxane etc.), aromatic compounds (eg toluene, xylene etc.), aliphatic compounds (eg pentane, hexane etc.), halogenated hydrocarbons (eg For example, methylene chloride, chlorobenzene, chloroform, and the like) and mixtures thereof can be used.

[Step 5]
Step 5 is a step in which a conductive layer is formed on the substrate. Specifically, this is a step in which the dispersion liquid is applied onto a transparent substrate by a desired application method (for example, spray coating, bar coating, roll coating, ink jet method, screen coating, etc.). If necessary, drying is performed after the coating step in order to remove the solvent contained in the coating film. A drying device (for example, a heating furnace, a far infrared furnace, a super far infrared furnace, or the like) is used for drying. Further, the substrate is cleaned as necessary.

[Step 6]
In step 6, a method of printing a conductive material on a substrate is usually used. There may be a step of providing dot spacers before or after step 6.

[Step 7]
A touch panel is produced by Step 7 in which the conductive layers of the obtained electrode substrate are bonded to each other. As described above, only one of the electrode substrates may be an electrode substrate having a conductive layer made of single-walled carbon nanotubes.

The capacitive touch panel of the present invention can be manufactured by the following steps (preferably in the order of step 8 to step 13).
Step 8: Step of obtaining crude carbon nanotube Step 9: Step of treating crude carbon nanotube with acid Step 10: Step of filtering single-walled carbon nanotube obtained in Step 9 Step 11: Single-walled carbon nanotube, fullerene, and solvent Step 12: Step of applying the single-walled carbon nanotube dispersion obtained in Step 11 on the substrate Step 13: Wiring is formed on the electrode substrate obtained in Step 12 Process to be Formed In addition, the process 8-the process 11 can be performed according to the said process 1-the process 4.
Further, the electrode substrate used in step 12 may be provided with a shield layer for noise removal on the surface opposite to the surface on which the conductive layer is formed.

  Hereinafter, more specific description will be given.

[Example 1]
Single-walled carbon nanotubes produced by the arc discharge method were treated with acid (treated with 63% nitric acid at 85 ° C. for 2 days (reaction)). Thereafter, filtration was performed, and single-walled carbon nanotubes were purified and recovered.

  10 mg of this single-walled carbon nanotube, 10 mg of hydroxyl group-containing fullerene (trade name Nanomuspectra D-100 Frontier Carbon), 1 mg of sodium hydroxide (Wako Pure Chemical Industries), 5 ml of water, 5 ml of 2-propanol, Were mixed. This mixed solution was subjected to ultrasonic irradiation for 1 minute (device name: ULTRASONIC HOGENIZER MODEL UH-600SR, manufactured by SMT). In this way, a single-walled carbon nanotube dispersion was obtained.

  This single-walled carbon nanotube dispersion was bar-coated on a PET film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) with a wet film thickness of 20 μm. Then, drying for 3 minutes was performed at 80 degreeC, and the transparent conductive layer was formed.

  According to observation with a scanning electron microscope, the single-walled carbon nanotubes in the transparent conductive layer were entangled with each other. And in this entangled location, the single-walled carbon nanotubes were in direct contact with each other. Of course, the single-walled carbon nanotubes were in direct contact with each other even at the places where they were not entangled. The conductive layer had a hydroxyl group-containing fullerene. However, binder resin is not included.

  Thereafter, the coated surface was washed with methanol. In this way, an electrode substrate was obtained.

[Example 2]
An electrode substrate was obtained in the same manner as in Example 1 except that the single-walled carbon nanotube dispersion obtained in Example 1 was applied a plurality of times so that the surface resistance was 400Ω / □.

[Example 3]
An electrode substrate was obtained in the same manner as in Example 1 except that the amount of single-walled carbon nanotubes added was reduced and coating was performed so that the surface resistance was 5000 Ω / □.

[Example 4]
The electrode substrate obtained in Example 1 was immersed in a solution obtained by diluting acrylic resin (trade name Watersol S-707-IM) with 2-propanol so that the solid content concentration was 1% by mass, and a transparent conductive layer An acrylic resin-based protective layer (wet film thickness 10 nm) was provided thereon.

[Comparative Example 1]
Vapor growth carbon nanofiber (trade name VGCF, manufactured by Showa Denko KK) 10 mg, acrylic resin (trade name Watersol S-707-IM) 10 mg (as solid content), and 2-propanol 10 ml were mixed. This mixed solution was subjected to ultrasonic irradiation (apparatus name: ULTRASONIC HOMOGENIZER MODEL UH-600SR, manufactured by SMT Co., Ltd.) for 1 minute to obtain a carbon nanofiber dispersion.
This carbon nanofiber dispersion was bar-coated with a wet film thickness of 50 μm on a PET film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.). Then, drying for 3 minutes was performed at 80 degreeC, and the transparent conductive layer was formed. Thereby, an electrode substrate was obtained.

[Characteristic]
The electrode substrates obtained in the above examples were examined for “total light transmittance”, “surface resistance value”, “keystroke test”, “sliding writing test”, “limit radius of curvature”, and “touch panel operability”. The results are shown in Tables 1 and 2.
Total light transmittance: The total light transmittance of the electrode substrate was measured using a direct reading haze computer (manufactured by Suga Test Instruments Co., Ltd.).
Surface resistance value: The surface resistance value of the electrode substrate was measured by a four-probe method using Loresta-EP (manufactured by Dia Instruments).
Keystroke test: The electrode substrate was subjected to the keystroke test under the conditions (3R silicon rubber, load 250 g, frequency 10 Hz (10 times per second), voltage 3 V).
Sliding writing test: The electrode substrate was subjected to the sliding writing test under the conditions (polyacetal pen, load 250 g, writing katakana character (20 × 20 mm)).
Limit curvature radius: An electrode substrate is wound around a rod having a certain radius. Then, the surface resistance was measured by the two-terminal method while pulling with a constant load. The radius at which the surface resistance value suddenly increased was defined as the critical curvature radius.
Touch panel operability: The obtained electrode substrate was the upper electrode, and the glass with ITO was the lower substrate. Then, a copper foil sheet was stretched on two opposite sides to form a counter electrode (see FIGS. 2 and 3). The upper electrode substrate and the lower electrode substrate were laminated so that the counter electrodes were orthogonal to each other, and a resistive film type touch panel was manufactured (see FIGS. 4 and 5). Then, when the interelectrode resistance of the lower electrode substrate is measured and the upper electrode substrate is pushed, the case where the resistance value of the lower electrode substrate changes is assumed to be a case of operating as a touch panel. A case where the operability was good was indicated by a circle, and a case where the operability was poor was indicated by a cross.

＊比較例２のものはＩＴＯ付ＰＥＴフィルム（東洋紡社製）
＊「表面抵抗値＊」は電極基板を８０℃のオーブンで１０日間放置後の測定値

* The comparative example 2 is a PET film with ITO (Toyobo Co., Ltd.)
* "Surface resistance value *" is the value measured after leaving the electrode substrate in an oven at 80 ° C for 10 days.

[Example 5]
The single-walled carbon nanotube dispersion obtained in Example 1 was bar-coated with a wet film thickness of 20 μm on a polycarbonate substrate with anti-Newton treatment. Then, drying for 3 minutes was performed at 80 degreeC, and the transparent conductive layer was formed. Thereafter, the coated surface was washed with methanol to obtain an electrode substrate.
The electrode substrate thus obtained was used as the lower substrate, the PET film with ITO was used as the upper substrate, and a resistive film type touch panel was produced in the same manner as described above. And when the upper board | substrate was pushed, the resistance value between electrodes of a lower board | substrate changed, and it was confirmed that the operativity as a touch panel is good.

[Example 6]
The electrode substrates obtained in Example 1 and Example 2 were used as an upper substrate and a lower substrate, respectively, and resistive film type touch panels were produced in the same manner as described above. And when the upper board | substrate was pushed, the resistance value between electrodes of a lower board | substrate changed, and it was confirmed that the operativity as a touch panel is good.

[Example 7]
The single-walled carbon nanotube dispersion obtained in Example 1 was bar-coated on a polycarbonate substrate with a wet film thickness of 50 μm. Then, drying for 3 minutes was performed at 80 degreeC, and the transparent conductive layer was formed. And the coating surface was wash | cleaned with methanol, and the electrode substrate was obtained. The electrode substrate thus obtained had a total light transmittance of 85% and a surface resistance value of 510Ω / □.
A capacitive touch panel (see FIG. 6) was fabricated using this electrode substrate. When an alternating current of 500 Hz, 1v was passed through the electrode substrate and the capacitive touch panel substrate was pressed, the current value changed, and it was confirmed that the touch panel has good operability.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2008-136118 for which it applied on May 24, 2008, and takes in those the indications of all here.

Claims (10)

A touch panel having an electrode substrate,
The electrode substrate is
A substrate,
A conductive layer provided on the substrate;
The conductive layer is
Having intertwined single-walled carbon nanotubes and fullerene hydroxide ,
A touch panel characterized by having no binder resin. The touch panel according to claim 1, wherein the amount of the fullerene is 10 to 1000 parts by mass with respect to 100 parts by mass of the single-walled carbon nanotube. The touch panel according to claim 1 or 2, wherein the single-walled carbon nanotube is a single-walled carbon nanotube obtained by an arc discharge method. The touch panel according to claim 1, wherein the single-walled carbon nanotube is an acid-treated single-walled carbon nanotube. The touch panel according to claim 1, wherein the substrate is a light-transmitting flexible substrate. The touch panel according to claim 1, wherein the electrode substrate has a protective layer provided on the conductive layer. The touch panel according to claim 1, wherein the electrode substrate has an anti-Newton layer. The touch panel according to claim 1, wherein the touch panel is a capacitive touch panel. The touch panel according to claim 1, wherein the touch panel is a resistive film type touch panel. The resistive film type touch panel is disposed so that the conductive layers of the electrode substrate face each other.
The touch panel, wherein at least one of the electrode substrates is an electrode substrate of the touch panel according to any one of claims 1 to 7.

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