Transparent conductive film

Abstract

This invention provides a transparent conductive film having a conductive layer comprising metal fibers, and is less prone to poor conductivity due to contact. The transparent conductive film of this invention comprises: a substrate; and a transparent conductive layer disposed on at least one side of the substrate; the transparent conductive layer comprises a polymer matrix and metal fibers present in the polymer matrix, and the arithmetic mean surface roughness Ra of the transparent conductive layer is 1.5 μm or more.

Description

Technical Field

[0001] This invention relates to a transparent conductive film. Prior Technology

[0002] Previously, transparent conductive films used as electrodes in touch sensors were often transparent conductive films with metal oxide layers such as indium-tin oxide (ITO) layers formed on resin films. However, transparent conductive films with metal oxide layers have insufficient flexibility and are prone to cracking due to physical stress such as bending.

[0003] Furthermore, as a transparent conductive film, a transparent conductive film containing a conductive layer made of metal fibers such as silver or copper has been proposed. This type of transparent conductive film has the advantage of excellent flexibility. On the other hand, the conductive layer containing metal fibers has low contact resistance, and the conductive film containing this conductive layer has the following problem: poor conductivity is prone to occur during transportation, storage, and other processes. Previous technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Publication No. 2009-505358 Summary of the Invention

[0005] [The problem the invention aims to solve]

[0006] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a transparent conductive film having a conductive layer containing metal fibers and not easily producing poor conductivity caused by contact. [Technical means to solve the problem]

[0007] The transparent conductive film of the present invention comprises: a substrate; and a transparent conductive layer disposed on at least one side of the substrate; the transparent conductive layer includes a polymer matrix and metal fibers present in the polymer matrix, and the arithmetic mean surface roughness Ra of the transparent conductive layer is 1.5 μm or more. In one embodiment, the metal fiber is a metal nanowire. In one embodiment, the aforementioned metal nanowires are silver nanowires. In one embodiment, the aforementioned transparent conductive film further comprises a metal layer. In one embodiment, the metal layer comprises copper. In one embodiment, the thickness of the transparent conductive layer is 50 nm to 300 nm. [Effects of the Invention]

[0008] According to the present invention, a transparent conductive film having a conductive layer comprising metal fibers and being less prone to poor conductivity caused by contact can be provided. Simple Explanation of the Diagram

[0009] Figure 1 is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. Figures 2(a) and (b) are schematic cross-sectional views of a transparent conductive film according to another embodiment of the present invention. Implementation

[0010] [A.] [Overall Structure of Transparent Conductive Film] [] Figure 1 is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. The transparent conductive film 100 includes: a substrate 10; and a transparent conductive layer 20 disposed on at least one side of the substrate 10 (both sides in the example). The transparent conductive layer 20 comprises a polymer matrix and metal fibers present in the polymer matrix. Although not shown, the transparent conductive film may further comprise any other suitable layers. In one embodiment, at least one outermost layer of the aforementioned transparent conductive film is a transparent conductive layer.

[0011] Figures 2(a) and (b) are schematic cross-sectional views of a transparent conductive film according to another embodiment of the present invention. The transparent conductive film 200 has a transparent conductive layer 20 disposed only on one side of the substrate 10. The transparent conductive film 300 further includes a metal layer 30. In the example of Figure 2(b), the transparent conductive film 300 is sequentially disposed with the transparent conductive layer 20, the substrate 10, and the metal layer 30.

[0012] In this invention, the arithmetic mean surface roughness Ra of the aforementioned transparent conductive layer is 1.5 μm or more. By ensuring that the arithmetic mean surface roughness Ra of the transparent conductive layer is within the aforementioned range, a transparent conductive film that is not prone to poor conductivity even when in contact with the transparent conductive layer can be obtained. Previously, when transparent conductive films were supplied in roll form, friction was applied to the surface due to mutual contact. In cases where a transparent conductive layer containing metal fibers was included, the bonding between the metal fibers could easily detach, leading to poor conductivity. On the other hand, the transparent conductive film of this invention, even when supplied in roll form, maintains the bonding between the metal fibers, thereby maintaining the required conductivity. Furthermore, even if the aforementioned transparent conductive film is a single sheet, it can prevent the bonding between the metal fibers from detaching due to contact, friction, etc., during the lamination of the transparent conductive film. Moreover, the aforementioned transparent conductive film not only exhibits excellent contact resistance to contact between transparent conductive films but also exhibits excellent contact resistance to contact with other objects. The arithmetic mean surface roughness Ra of the aforementioned transparent conductive layer is preferably 2.0 μm to 5.0 μm, more preferably 3.0 μm to 4.0 μm, and even more preferably 3.0 μm to 3.5 μm. Within this range, the aforementioned effects become significant. The arithmetic mean surface roughness Ra can be measured using an atomic force microscope.

[0013] The surface resistivity of the transparent conductive film of the present invention is preferably 0.01 Ω / □ to 1000 Ω / □, more preferably 0.1 Ω / □ to 500 Ω / □, particularly preferably 0.1 Ω / □ to 300 Ω / □, and most preferably 0.1 Ω / □ to 100 Ω / □. In one embodiment, the surface resistivity of the transparent conductive film is 100 Ω / □ or less.

[0014] The haze value of the transparent conductive film of the present invention is preferably below 1%, more preferably below 0.7%, and even more preferably below 0.5%. The lower the haze value, the better, but its lower limit is, for example, 0.05%.

[0015] The transparent conductive film of the present invention preferably has a total light transmittance of 80% or more, more preferably 85% or more, and especially preferably 90% or more.

[0016] The thickness of the transparent conductive film of the present invention is preferably 10 μm to 500 μm, more preferably 15 μm to 300 μm, and even more preferably 20 μm to 200 μm.

[0017] [B.] [Transparent Conductive Layer] [] As described above, the transparent conductive layer comprises metal fibers and a polymer matrix.

[0018] The thickness of the aforementioned transparent conductive layer is preferably 50 nm to 300 nm, and more preferably 80 nm to 200 nm. By setting the thickness of the transparent conductive layer to 50 nm or more, a transparent conductive layer with a low coefficient of kinetic friction can be formed.

[0019] The total light transmittance of the aforementioned transparent conductive layer is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more.

[0020] The coefficient of kinetic friction of the transparent conductive layer relative to the transparent conductive layer is preferably 2.0 or less, more preferably 1.8 or less, further preferably 1.5 or less, further preferably 1.2 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. The smaller the coefficient of kinetic friction of the transparent conductive layer relative to the transparent conductive layer, the better, but its lower limit is, for example, 0.05. Within this range, a transparent conductive film that is not prone to poor conductivity even when in contact with the transparent conductive layer can be obtained. The term "coefficient of kinetic friction of the transparent conductive layer relative to the transparent conductive layer" refers to the coefficient of kinetic friction between the transparent conductive layer of the transparent conductive film and a transparent conductive layer having the same composition as the transparent conductive layer of the transparent conductive film. In this specification, the coefficient of kinetic friction is measured according to JIS K7125:1999, with a measurement load of 100 g, a measurement speed of 1 mm / s, and a measurement distance of 30 mm.

[0021] In one embodiment, the coefficient of kinetic friction when the transparent conductive layer and the surface opposite to it are in contact is preferably 2.0 or less, more preferably 1.8 or less, further preferably 1.5 or less, further preferably 1.2 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. The smaller the coefficient of kinetic friction when the transparent conductive layer and the surface opposite to it are in contact, the better, but its lower limit is, for example, 0.05. "The surface opposite to the transparent conductive layer" refers to the outermost surface opposite to the surface of the transparent conductive layer being measured, with the substrate as a reference. Therefore, when the transparent conductive film is composed of transparent conductive layer A / substrate / transparent conductive layer A, "the coefficient of kinetic friction when the transparent conductive layer and the surface opposite to it are in contact" refers to the coefficient of kinetic friction when the transparent conductive layers are in contact with each other (transparent conductive layer A and transparent conductive layer A), which has the same meaning as "the coefficient of kinetic friction of the transparent conductive layer relative to the transparent conductive layer". Furthermore, when the transparent conductive film is composed of a transparent conductive layer / substrate, the "coefficient of kinetic friction when the transparent conductive layer and the surface opposite to it are in contact" refers to the coefficient of kinetic friction when the transparent conductive layer is in contact with the substrate. If the coefficient of kinetic friction when the transparent conductive layer and the surface opposite to it are in contact is within the above range, then when the transparent conductive film is laminated, or when the transparent conductive film is made into a roll shape, poor conductivity can be significantly prevented.

[0022] In one embodiment, the aforementioned transparent conductive layer is patterned. As a patterning method, any suitable method can be used depending on the shape of the transparent conductive layer. The pattern shape of the transparent conductive layer can be any suitable shape depending on the application. Examples include the patterns described in Japanese Patent Publication No. 2011-511357, Japanese Patent Publication No. 2010-164938, Japanese Patent Publication No. 2008-310550, Japanese Patent Publication No. 2003-511799, and Japanese Patent Publication No. 2010-541109. After the transparent conductive layer is formed on the substrate, it can be patterned using any suitable method according to the shape of the transparent conductive layer.

[0023] Metal nanowires are preferred as the aforementioned metal fibers. These metal nanowires refer to conductive materials made of metal, shaped like needles or filaments, and with a diameter at the nanometer level. Metal nanowires can be straight or curved. If a transparent conductive layer containing metal nanowires is used, the metal nanowires form a mesh, and by bonding them individually, a good conductive path can be formed, resulting in a transparent conductive film with low resistance.

[0024] The ratio of the thickness d to the length L of the aforementioned metal nanowires (length-to-diameter ratio: L / d) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 10,000. Using metal nanowires with such a large length-to-diameter ratio allows for good intersecting, enabling higher conductivity with a smaller number of nanowires. This results in a transparent conductive film with high light transmittance. Furthermore, in this specification, the term "thickness of the metal nanowire" refers to its diameter when the cross-section of the metal nanowire is circular, its minor axis when the cross-section is elliptical, and its longest diagonal when the cross-section is polygonal. The thickness and length of the metal nanowires can be confirmed using a scanning electron microscope or a transmission electron microscope.

[0025] The thickness of the aforementioned metal nanowires is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 60 nm. If this range is met, a transparent conductive layer with high light transmittance can be formed.

[0026] The length of the aforementioned metal nanowires is preferably 1 μm to 1000 μm, more preferably 1 μm to 500 μm, and particularly preferably 1 μm to 100 μm. Within this range, a transparent conductive film with high conductivity can be obtained.

[0027] As for the metal constituting the aforementioned metal nanowires, any suitable metal can be used as long as it has high conductivity. Examples of metals constituting the aforementioned metal nanowires include silver, gold, copper, and nickel. Furthermore, materials obtained by plating such metals (e.g., gold plating) can also be used. Preferably, the metal nanowires comprise one or more metals selected from the group consisting of gold, platinum, silver, and copper. In one embodiment, the aforementioned metal nanowires are silver nanowires.

[0028] As a method for manufacturing the aforementioned metal nanowires, any suitable method can be employed. For example, methods such as reducing silver nitrate in solution and applying an external voltage or current to the surface of a precursor from the tip of a probe to pull out the metal nanowire from the tip of the probe, thereby continuously forming the metal nanowire, can be exemplified. In the method of reducing silver nitrate in solution, silver nanowires can be synthesized by liquid-phase reduction of silver salts such as silver nitrate in the presence of polyols such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires can be mass-produced, for example, according to the methods described in Xia, Y. etal., Chem. Mater. (2002), 14, 4736-4745 and Xia, Y. etal., Nano letters (2003) 3 (7), 955-960.

[0029] Regarding the content ratio of metal nanowires in the aforementioned transparent conductive layer, it is preferably 80% by weight or less relative to the total weight of the transparent conductive layer. Within this range, a transparent conductive layer with a low coefficient of kinetic friction can be formed. More preferably, the content ratio of metal nanowires in the aforementioned transparent conductive layer is 30% to 75% by weight, more preferably 30% to 65% by weight, and even more preferably 45% to 65% by weight. Within this range, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

[0030] Any suitable polymer can be used as the polymer constituting the polymer matrix described above. Examples of such polymers include: acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, and polyamide-imide; polyurethane polymers; epoxy polymers; polyolefin polymers; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone polymers; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; and fluoropolymers. Preferably, a curing resin containing multifunctional acrylates such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), and trimethylolpropane triacrylate (TMPTA) is used (preferably a UV-curing resin).

[0031] The density of the transparent conductive layer is preferably 1.3 g / cm³ to 10.5 g / cm³, more preferably 1.5 g / cm³ to 3.0 g / cm³. Within this range, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

[0032] A transparent conductive layer can be formed by coating a conductive layer forming composition containing metal fibers (e.g., metal nanowires) onto a substrate (or a laminate of a substrate and other layers), followed by drying the coating. The conductive layer forming composition may contain a resin material that forms a polymer matrix. Alternatively, the resin material that forms the polymer matrix and the conductive layer forming composition may be prepared separately. After coating and drying the conductive layer forming composition, a resin material (polymer composition, monomer composition) is coated onto the layer containing metal fibers, followed by drying or hardening of the resin material coating to form a transparent conductive layer.

[0033] In addition to metal fibers (e.g., metal nanowires), the above-mentioned conductive layer forming composition may also contain any suitable solvent. The conductive layer forming composition can be prepared in the form of a dispersion of metal fibers (e.g., metal nanowires). Examples of such solvents include water, alcohol-based solvents, ketone-based solvents, ether-based solvents, hydrocarbon-based solvents, and aromatic solvents. From the viewpoint of reducing environmental impact, water is preferred. The above-mentioned conductive layer forming composition may further contain any suitable additives depending on the purpose. Examples of such additives include corrosion inhibitors to prevent corrosion of the metal fibers (e.g., metal nanowires) and surfactants to prevent aggregation of the metal fibers (e.g., metal nanowires). The type, quantity, and amount of additives used can be appropriately determined according to the purpose.

[0034] The dispersion concentration of the metal fibers (e.g., metal nanowires) in the above-mentioned conductive layer forming composition is preferably 0.1% to 1% by weight. If it is within this range, a transparent conductive layer with excellent conductivity and light transmittance can be formed.

[0035] As a coating method for the above-mentioned conductive layer forming composition, any suitable method can be used. Examples of coating methods include: spray coating, rod coating, roller coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, gravure printing, photogravure printing, etc. As a drying method for the coated layer, any suitable drying method can be used (e.g., natural drying, air drying, heat drying). For example, in the case of heat drying, the drying temperature is typically 50°C to 200°C, preferably 80°C to 150°C. The drying time is typically 1 to 10 minutes.

[0036] The polymer solution described above contains the polymer constituting the polymer matrix, or the polymer precursor (monomer constituting the polymer).

[0037] The polymer solution described above may contain a solvent. Examples of solvents included in the polymer solution include: alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, or aromatic solvents. Preferably, the solvent is volatile. The boiling point of the solvent is preferably below 200°C, more preferably below 150°C, and even more preferably below 100°C.

[0038] [C.] [Substrate] [] The aforementioned substrate typically includes any suitable resin. Examples of resins constituting the substrate include: cyclic olefin resins, polyimide resins, polyvinylidene chloride resins, polyvinyl chloride resins, polyethylene terephthalate resins, and polyethylene naphthalate resins. Cyclic olefin resins are preferred. Using a substrate containing a cyclic olefin resin results in a transparent conductive film with excellent flexibility.

[0039] Polynorcamphene is a preferred example of the aforementioned cyclic olefin resin. Polynorcamphene refers to a (co)polymer obtained by using a portion or all of a norcamphene-based monomer having a norcamphene ring as one of the starting materials (monomers). Various commercially available products are available as polynorcamphene. Specific examples include: ZEONEX and ZEONOR manufactured by Zeon Corporation of Japan; Arton manufactured by JSR Corporation; TOPAS manufactured by TICNA Corporation; and APEL manufactured by Mitsui Chemicals Corporation.

[0040] The glass transition temperature of the resin constituting the above-mentioned substrate is preferably 50°C to 200°C, more preferably 60°C to 180°C, and even more preferably 70°C to 160°C. If the substrate has a glass transition temperature within this range, deterioration during the formation of a transparent conductive laminate can be prevented.

[0041] The thickness of the aforementioned substrate is preferably 8 μm to 500 μm, more preferably 10 μm to 250 μm, even more preferably 10 μm to 150 μm, and particularly preferably 15 μm to 100 μm.

[0042] The total light transmittance of the aforementioned substrate is preferably 80% or higher, more preferably 85% or higher, and especially preferably 90% or higher. Within this range, a transparent conductive film that is preferable for use as a transparent conductive film in touch panels and the like can be obtained.

[0043] The aforementioned substrate may further include any suitable additives as needed. Specific examples of additives include: plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and tackifiers. The types and amounts of additives used can be appropriately determined according to the purpose.

[0044] Various surface treatments can be applied to the aforementioned substrate as needed. Surface treatment can be performed using any suitable method depending on the purpose. Examples include: low-voltage plasma treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, and acid or alkali treatment. In one embodiment, the transparent substrate is surface-treated to make its surface hydrophilic. If the substrate is made hydrophilic, the processability is excellent when coating a composition for forming a transparent conductive layer prepared using an aqueous solvent. Furthermore, a transparent conductive film with excellent adhesion between the substrate and the transparent conductive layer can be obtained.

[0045] [D.] [Metallic layer] [] The aforementioned metal layer comprises any suitable metal. Preferably, it comprises conductive metals such as silver, gold, copper, and nickel. In one embodiment, the aforementioned metal layer comprises copper.

[0046] The aforementioned metal layer can be formed by any suitable method. The aforementioned metal layer can be formed by dry processes such as vapor deposition or sputtering, CVD (Chemical Vapor Deposition), or wet processes such as plating. [Example]

[0047] The present invention will be specifically described below by way of examples, but the present invention is not limited to these examples.

[0048] [Manufacturing Example 1] (Manufacturing of metal nanowires) Anhydrous ethylene glycol (5 ml) and anhydrous ethylene glycol solution of PtCl₂ (concentration: 1.5 × 10⁻⁴ mol / L) were added to a reaction vessel equipped with a stirrer at 160°C. After 4 minutes, anhydrous ethylene glycol solution of AgNO₃ (concentration: 0.12 mol / L) and anhydrous ethylene glycol solution of polyvinylpyrrolidone (MW: 55000) (concentration: 0.36 mol / L) were simultaneously added dropwise to the obtained solution over a period of 6 minutes. After this addition, the mixture was heated to 160°C and reacted for more than 1 hour until AgNO₃ was completely reduced to form silver nanowires. Subsequently, acetone was added to the reaction mixture containing silver nanowires obtained in the above manner until the volume of the reaction mixture reached 5 times its original volume. The reaction mixture was then centrifuged (2000 rpm, 20 minutes) to obtain the silver nanowires. The silver nanowires (concentration: 0.2 wt%) and pentaethylene glycol dodecyl ether (concentration: 0.1 wt%) were dispersed in pure water to prepare silver nanowire ink.

[0049] [Example 1] Using a bar coater, the silver nanowire ink obtained in Manufacturing Example 1 was coated onto a substrate (cyclic olefin film) with a resistivity of 50 Ω / □ after film formation, and the film was formed by heating at 120°C for 2 minutes. Next, a coating solution a is prepared. This coating solution a is prepared by diluting a photocurable resin with urethane acrylate as the main component to a solid content concentration of 1.5% using a mixed solvent of isopropanol (IPA) and diacetone alcohol (DAA) (mixing ratio (by weight) IPA:DAA=8:2). Using a spin coater, the coating solution a is coated onto the surface of the above-mentioned silver nanowire ink with a dry film thickness of 70 nm. After heating at 80°C for 1 minute, the film is irradiated with ultraviolet light with a cumulative exposure of 450 mJ / cm2 using a high-pressure mercury lamp to form a transparent conductive layer A, thereby obtaining a transparent conductive film A containing a substrate and a transparent conductive layer A. The transparent conductive film A is provided for the following evaluation. (1) Coefficient of kinetic friction relative to transparent conductive layer A Using the trade name "TSf-503" manufactured by Kyowa Interface Chemical Co., Ltd., and in accordance with JIS K7125:1999, the coefficient of kinetic friction was measured by sliding transparent conductive layer A against transparent conductive layer A under the following conditions: sample size (transparent conductive layer A) on the contact side: 1 cm□, measurement load: 100 g, measurement speed: 1 mm / s, measurement distance: 30 mm, and measurement temperature: 23°C. (2) Static friction coefficient Using the trade name "TSf-503" manufactured by Kyowa Interface Chemical Co., Ltd., and in accordance with JIS K7125:1999, the coefficient of friction (static friction coefficient) at the start of sliding was measured under the following conditions: sample size (transparent conductive layer A) on the contact side: 1 cm□, measurement load: 100 g, measurement speed: 1 mm / s, measurement distance: 30 mm, and measurement temperature: 23°C. (3) Rate of increase in resistance value Except for setting the load to 300 g, under the conditions for measuring the above-mentioned coefficient of kinetic friction, the transparent conductive layers A were slid together once at a distance of 3 cm. For the aforementioned sliding position and other positions, the surface resistance value of the transparent conductive layer was measured using a non-contact surface resistance meter (manufactured by NAPSON, trade name "EC-80", thin film resistance measurement mode, room temperature: 26°C). The rate of increase in resistance caused by sliding is calculated using the formula (resistance value of the surface at the sliding position / resistance value of the surface outside the sliding part). (4) Arithmetic mean roughness Ra of transparent conductive layer A The arithmetic mean roughness Ra of a 5 μm × 5 μm region on the surface of the transparent conductive layer A was measured using the tapping mode of the "NanoscopeIV" scanning probe microscope manufactured by Veeco Instruments.

[0050] [Refer to Example 1-1] A transparent conductive film A was obtained in the same manner as in Example 1. (1a) Coefficient of kinetic friction relative to the copper film on the transparent conductive layer A In addition, a transparent conductive film A was obtained in the same manner as in Example 1. A copper film with a thickness of 100 nm was sputtered onto the transparent conductive layer A of the obtained transparent conductive film A to obtain a transparent conductive film with a copper film attached. The sample on the contact side was used as the transparent conductive film with a copper film attached, and the coefficient of kinetic friction was measured by sliding the transparent conductive layer A and the copper film on the transparent conductive layer A using the same method as described in (1) above. (2a) Static friction coefficient In addition, a transparent conductive film A was obtained in the same manner as in Example 1. A copper film with a thickness of 100 nm was sputtered onto the transparent conductive layer A of the obtained transparent conductive film A to obtain a transparent conductive film with a copper film attached. Using the sample on the contact side as the transparent conductive film with a copper film attached, the coefficient of friction (static friction coefficient) at the start of sliding was measured by sliding the transparent conductive layer A and the copper film on the transparent conductive layer A using the same method as described in (2) above. (3a) Rate of increase in resistance value The rate of increase in resistance caused by sliding is measured by sliding the transparent conductive layer A and the copper film on the transparent conductive layer A using the same method as in (3) above. (4a) Arithmetic mean roughness Ra of the copper film on the transparent conductive layer A The arithmetic mean roughness Ra of the copper film on the transparent conductive layer A was determined by the same method as described in (4) above.

[0051] [Refer to Example 1-2] A transparent conductive film A was obtained in the same manner as in Example 1. (1b) Coefficient of kinetic friction relative to the transparent conductive layer d Using a bar coater, the silver nanowire ink obtained in Manufacturing Example 1 was coated onto a substrate (cyclic olefin film) with a resistivity of 50 Ω / □ after film formation, and the film was formed by heating at 120°C for 2 minutes. Next, a coating solution a is prepared. This coating solution a is prepared by diluting a photocurable resin with urethane acrylate as the main component with methyl isobutyl ketone to a solid content concentration of 1.5%. Using a spin coater, the coating solution a is coated on the above-mentioned silver nanowire ink coating surface with a dry film thickness of 70 nm. After heating at 80°C for 1 minute, it is irradiated with ultraviolet light with a cumulative exposure of 450 mJ / cm2 using a high-pressure mercury lamp to form a transparent conductive layer d, thereby obtaining a transparent conductive film d containing a substrate / transparent conductive layer d. The sample on the contact side is used as a transparent conductive film d. The coefficient of kinetic friction is measured by sliding the transparent conductive layer A and the transparent conductive layer d using the same method as described in (1) above. (2b) Static friction coefficient The sample on the contact side is used as a transparent conductive film d. The coefficient of friction (static friction coefficient) at the start of sliding is measured by sliding the transparent conductive layer A and the transparent conductive layer d using the same method as described in (2). (3b) Rate of increase in resistance value The rate of increase in resistance caused by sliding is measured by sliding transparent conductive layer A and transparent conductive layer d using the same method as in (3) above. (4b) Arithmetic mean roughness Ra of transparent conductive layer d The arithmetic mean roughness Ra of the transparent conductive layer d was determined by the same method as described in (4) above.

[0052] [Refer to Examples 1-3] A transparent conductive film A was obtained in the same manner as in Example 1. (1c) Coefficient of dynamic friction relative to cyclic olefin film The sample on the contact side was used as a cyclic olefin film (manufactured by Zeon Corporation of Japan, trade name "ZF16"). The coefficient of kinetic friction was measured by sliding the transparent conductive layer A and the cyclic olefin film using the same method as described in (1). (2c) Static friction coefficient The sample on the contact side was used as a cyclic olefin film (manufactured by Zeon Corporation of Japan, trade name "ZF16"). The coefficient of friction (static friction coefficient) at which the transparent conductive layer A and the cyclic olefin film began to slide were measured by the same method as described in (2). (3c) Rate of increase in resistance value The rate of increase in resistance caused by sliding was measured by sliding the transparent conductive layer A against the cycloolefin film using the same method as described in (3) above. (4c) Arithmetic mean roughness Ra of cycloolefin membrane The arithmetic mean roughness Ra of the above cycloolefin film was determined by the same method as in (4) above.

[0053] [Refer to Examples 1-4] A transparent conductive film A was obtained in the same manner as in Example 1. (1d) Coefficient of dynamic friction relative to PET film The sample on the contact side was used as a PET film (manufactured by KOLON industry, trade name "CE900"). The coefficient of kinetic friction was measured by sliding the transparent conductive layer A against the PET film using the same method as described in (1) above. (2d) Static friction coefficient The sample on the contact side was used as a PET film (manufactured by KOLON industry, trade name "CE900"). The coefficient of friction (static friction coefficient) at which the transparent conductive layer A and the PET film slid together was measured by the same method as described in (2) above. (3d) Rate of increase in resistance value The rate of increase in resistance caused by sliding was measured by sliding the transparent conductive layer A against the PET film using the same method as described in (3) above. (4d) Arithmetic mean roughness Ra of PET film The arithmetic mean roughness Ra of the PET film was determined by the same method as described in (4) above.

[0054] [Refer to Examples 1-5] A transparent conductive film A was obtained in the same manner as in Example 1. (1e) Coefficient of kinetic friction relative to acrylic film The sample on the contact side was used as an acrylic film (manufactured by Toyo Steel Sheet Co., Ltd., trade name "HX-40-UF"). The coefficient of kinetic friction was measured by sliding the transparent conductive layer A against the acrylic film using the same method as described in (1) above. (2e) Static friction coefficient The sample on the contact side was used as an acrylic film (manufactured by Toyo Steel Sheet Co., Ltd., trade name "HX-40-UF"). The coefficient of friction (static friction coefficient) at which the transparent conductive layer A and the acrylic film began to slide were measured by the same method as described in (2) above. (3e) Rate of increase in resistance value The rate of increase in resistance caused by sliding was measured by sliding the transparent conductive layer A against the acrylic film using the same method as described in (3) above. (4e) Arithmetic mean roughness Ra of acrylic film The arithmetic mean roughness Ra of the acrylic film was determined by the same method as described in (4) above.

[0055] [Example 2] Except that the thickness of the dried film of coating liquid a is set to 100 nm, a transparent conductive film B containing a substrate / transparent conductive layer B is obtained in the same manner as in Example 1. Transparent conductive film B is provided for the following evaluation. (1B) Coefficient of kinetic friction relative to transparent conductive layer B Using the trade name "TSf-503" manufactured by Kyowa Interface Chemical Co., Ltd., and in accordance with JIS K7125:1999, the coefficient of kinetic friction was measured by sliding transparent conductive layer B against transparent conductive layer B under the following conditions: sample size (transparent conductive layer B) on the contact side: 1 cm□, measurement load: 100 g, measurement speed: 1 mm / s, measurement distance: 30 mm, and measurement temperature: 23°C. (2B) Static friction coefficient Using the trade name "TSf-503" manufactured by Kyowa Interface Chemical Co., Ltd., and in accordance with JIS K7125:1999, the coefficient of friction (static friction coefficient) at the start of sliding was measured under the following conditions: sample size (transparent conductive layer B) on the contact side: 1 cm□, measurement load: 100 g, measurement speed: 1 mm / s, measurement distance: 30 mm, and measurement temperature: 23°C. (3B) Rate of increase in resistance value Except for setting the load to 300 g, under the conditions for measuring the above-mentioned coefficient of kinetic friction, the transparent conductive layers B were slid together once at a distance of 3 cm. For the aforementioned sliding position and other positions, the surface resistance value of the transparent conductive layer was measured using a non-contact surface resistance meter (manufactured by NAPSON, trade name "EC-80", thin film resistance measurement mode, room temperature: 26°C). The rate of increase in resistance caused by sliding is calculated using the formula (resistance value of the surface at the sliding position / resistance value of the surface outside the sliding part). (4B) Arithmetic mean roughness Ra of transparent conductive layer B The arithmetic mean roughness Ra of a 5 μm × 5 μm region on the surface of the transparent conductive layer B was measured using the tapping mode of the "NanoscopeIV" scanning probe microscope manufactured by Veeco Instruments.

[0056] [Comparative Example 1] Similar to Example 1, the silver nanowire layer was filmed. Then, a coating solution c was prepared, which was made by adding a silane coupling agent to a photocurable resin with urethane acrylate as the main component, and diluting it with methyl isobutyl ketone to a solid content concentration of 1.5%. Using a spin coater, the coating solution c was coated onto the silver nanowire ink coating surface to achieve a dry film thickness of 70 nm. After heating at 80°C for 1 minute, it was irradiated with ultraviolet light with a cumulative exposure of 450 mJ / cm² using a high-pressure mercury lamp to form a transparent conductive layer C, thus obtaining a transparent conductive film C comprising a substrate and transparent conductive layer C. (1f) Coefficient of kinetic friction relative to the transparent conductive layer C The sample on the contact side is used as the transparent conductive layer C. The coefficient of kinetic friction is measured by sliding the transparent conductive layer C against the transparent conductive layer C using the same method as described in (1). (2f) Static friction coefficient The sample on the contact side is used as the transparent conductive layer C. The friction coefficient (static friction coefficient) at the start of sliding is measured by sliding the transparent conductive layer C with the transparent conductive layer C using the same method as described in (2). (3f) Rate of increase in resistance value The rate of increase in resistance caused by sliding was measured by sliding the transparent conductive layer C against the cycloolefin film using the same method as described in (3) above. (4f) Arithmetic mean roughness Ra of transparent conductive layer C The arithmetic mean roughness Ra of the transparent conductive layer C was determined by the same method as described in (4) above.

[0057] [Comparative Example 2] A transparent conductive film d comprising a substrate / transparent conductive layer d is obtained by means of the same method as described in Reference Examples 1-2. (1g) Coefficient of kinetic friction relative to the transparent conductive layer d The sample on the contact side is used as the transparent conductive layer d. The coefficient of kinetic friction is measured by sliding the transparent conductive layer d with the transparent conductive layer d using the same method as described in (1). (2g) Static friction coefficient The sample on the contact side is used as the transparent conductive layer d. The friction coefficient (static friction coefficient) at the start of sliding is measured by sliding the transparent conductive layer d with the transparent conductive layer d using the same method as described in (2) above. (3g) Rate of increase in resistance value The rate of increase in resistance caused by sliding was measured by sliding the transparent conductive layer d against the cycloolefin film using the same method as described in (3) above. (4g) Arithmetic mean roughness Ra of transparent conductive layer d The arithmetic mean roughness Ra of the transparent conductive layer d was determined by the same method as described in (4) above.

[0058] [Compare with Example 2-1] A transparent conductive film d was obtained in the same manner as in Comparative Example 2. (1h) Coefficient of kinetic friction relative to the copper film on the transparent conductive layer d In addition, a transparent conductive film d was obtained in the same manner as in Comparative Example 2. A copper film with a thickness of 100 nm was sputtered onto the transparent conductive layer d of the obtained transparent conductive film d to obtain a transparent conductive film with a copper film attached. The sample on the contact side was used as the transparent conductive film with a copper film attached, and the coefficient of kinetic friction was measured by sliding the transparent conductive layer d and the copper film on the transparent conductive layer d using the same method as described in (1) above. (2h) Static friction coefficient The sample on the contact side is used as the transparent conductive film with copper film attached as described above. The coefficient of friction (static friction coefficient) at the start of sliding is measured by sliding the transparent conductive layer d with the copper film on the transparent conductive layer d using the same method as described in (2). (3h) Resistance rise rate The rate of increase in resistance caused by sliding is measured by sliding the transparent conductive layer d and the copper film on the transparent conductive layer d using the same method as in (3) above. (4h) Arithmetic mean roughness Ra of the copper film on the transparent conductive layer d The arithmetic mean roughness Ra of the copper film on the transparent conductive layer d was determined by the same method as described in (4) above.

[0059] The evaluation results of the above-described embodiments, reference examples, comparative examples, and comparative reference examples are shown in Table 1. Furthermore, in the table, the sample on the contact side in terms of the coefficient of kinetic friction and the rate of increase in value is denoted as "the layer in contact with the transparent conductive layer". [Table 1] Transparent conductive layer (the surface being slidable) Layer in contact with transparent conductive layer coefficient of kinetic friction static friction coefficient Rate of increase in resistance Ra (μm) of the transparent resin layer Ra (μm) of the layer in contact with the transparent conductive layer. Example 1 Transparent conductive layer A Transparent conductive layer A 0.68 0.62 1 3.1 3.1 See Example 1-1 Transparent conductive layer A Transparent conductive layer A+ copper film 0.46 0.46 1 3.1 3.6 See Example 1-2 Transparent conductive layer A transparent conductive layer d 0.95 0.97 1 3.6 0.7 Reference Example 1-3 Transparent conductive layer A Cycloolefin membranes 0.82 0.78 1 3.1 1 See Example 1-4 Transparent conductive layer A PET film 0.71 0.68 1 3.1 1.1 See Example 1-5 Transparent conductive layer A acrylic film 0.21 0.18 1 3.1 1.3 Example 2 Transparent conductive layer B Transparent conductive layer B 1.44 1 1 2.4 2.4 Comparative example 1 Transparent conductive layer C Transparent conductive layer C 2.97 2.84 1.2 1.1 1.1 Comparative example 2 transparent conductive layer d transparent conductive layer d 4.76 7.44 1.5 0.7 0.7 Comparative Example (Reference Example) 2-1 transparent conductive layer d Transparent conductive layer d+ copper film 3.54 1.76 1.4 0.7 1

[0060] As shown in Table 1, according to the present invention, by specifying the arithmetic mean surface roughness Ra of the transparent conductive layer, a transparent conductive film containing a conductive layer with metal fibers can be provided, which is less prone to poor conductivity caused by contact. As shown in the reference example, even when such a transparent conductive film is in contact with or slides against various films, the increase in resistance value is suppressed.

[0061] 10: Substrate 20: Transparent conductive layer 30: Metal layer 100: Transparent conductive film 200: Transparent conductive film 300: Transparent conductive film

Claims

1. A transparent conductive film comprising: a substrate; and a transparent conductive layer disposed on at least one side of the substrate; the transparent conductive layer comprising a polymer matrix and metal fibers present in the polymer matrix, the metal fibers being metal nanowires, the thickness of the transparent conductive layer being 50 nm to 100 nm, the content ratio of the metal nanowires in the transparent conductive layer being 30% to 80% by weight, and the arithmetic mean surface roughness Ra of the transparent conductive layer being 3 nm to 5 nm.

2. The transparent conductive film as claimed in claim 1, wherein the aforementioned metal nanowires are silver nanowires.

3. The transparent conductive film of claim 1 or 2 further comprises a metal layer.

4. The transparent conductive film of claim 3, wherein the metal layer comprises copper.

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