JP7707334B2 - Transparent Conductive Film - Google Patents

Description

The present invention relates to a transparent conductive film.

Conventionally, transparent conductive films that have a metal oxide layer, such as an indium tin composite oxide layer (ITO layer), formed on a resin film have been widely used as transparent conductive films for use in electrodes of touch sensors, etc. However, transparent conductive films with a metal oxide layer formed on them have a problem in that they are insufficient in bendability and are prone to cracking due to physical stress such as bending.

As a transparent conductive film, a transparent conductive film with a conductive layer containing metal fibers made of silver, copper, etc. has been proposed. Such transparent conductive films have the advantage of excellent flexibility. On the other hand, conductive layers containing metal fibers have low contact resistance, and conductive films with such conductive layers have the problem of being prone to poor conductivity during transportation, storage, etc.

Special Publication No. 2009-505358

The present invention has been made to solve the above problems, and its purpose is to provide a transparent conductive film that has a conductive layer containing metal fibers, but is unlikely to suffer from poor conductivity due to contact.

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 containing a polymer matrix and metal fibers present in the polymer matrix, and the transparent conductive layer has an arithmetic mean surface roughness Ra of 1.5 nm or more.
In one embodiment, the metal fibers are metal nanowires.
In one embodiment, the metal nanowires are silver nanowires.
In one embodiment, the transparent conductive film further comprises a metal layer.
In one embodiment, the metal layer is composed of copper.
In one embodiment, the transparent conductive layer has a thickness of 50 nm to 300 nm.

The present invention provides a transparent conductive film that is unlikely to suffer from poor conductivity due to contact, while having a conductive layer that contains metal fibers.

1 is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a transparent conductive film according to another embodiment of the present invention.

A. Overall Configuration of Transparent Conductive Film FIG. 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 (both sides in the illustrated example) of the substrate 10. The transparent conductive layer 20 includes a polymer matrix and metal fibers present in the polymer matrix. Although not illustrated, the transparent conductive film may further include any other suitable layers. In one embodiment, at least one outermost layer of the transparent conductive film is a transparent conductive layer.

2(a) and (b) are schematic cross-sectional views of a transparent conductive film according to another embodiment of the present invention. In the transparent conductive film 200, a transparent conductive layer 20 is disposed on only one side of the substrate 10. The transparent conductive film 300 further includes a metal layer 30. In the example of FIG. 2(b), the transparent conductive film 300 includes a metal layer 20, a substrate 10, and a metal layer 30 disposed in this order.

In the present invention, the arithmetic mean surface roughness Ra of the transparent conductive layer is 1.5 nm or more. By setting the arithmetic mean surface roughness Ra of the transparent conductive layer in the above range, a transparent conductive film that is unlikely to cause poor conductivity even when contact occurs with the transparent conductive layer can be obtained. When conventional transparent conductive films are provided in the form of a roll, frictional force is applied to the surface by contact with each other, and when a transparent conductive layer containing metal fibers is provided, the bonding between the metal fibers is easily released and poor conductivity occurs. On the other hand, even when the transparent conductive film of the present invention is provided in the form of a roll, the bonding between the metal fibers is maintained and the desired conductivity is maintained. In addition, even if the transparent conductive film is a sheet, the bonding between the metal fibers due to contact, friction, etc. when the transparent conductive film is laminated can be prevented. In addition, the transparent conductive film can exhibit excellent contact resistance not only to contact between transparent conductive films, but also to contact with other objects. The transparent conductive layer has an arithmetic mean surface roughness Ra of preferably 2.0 nm to 5.0 nm , more preferably 3.0 nm to 4.0 nm , and even more preferably 3.0 nm to 3.5 nm . Within such a range, the above-mentioned effects are significant. The arithmetic mean surface roughness Ra can be measured using an atomic force microscope.

The surface resistance value 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 resistance value of the transparent conductive film is 100 Ω/□ or less.

The haze value of the transparent conductive film of the present invention is preferably 1% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The smaller the haze value, the better, but the lower limit is, for example, 0.05%.

The total light transmittance of the transparent conductive film of the present invention is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more.

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.

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

The thickness of the transparent conductive layer is preferably 50 nm to 300 nm, and more preferably 80 nm to 200 nm. By making the thickness of the transparent conductive layer 50 nm or more, a transparent conductive layer with a small dynamic friction coefficient can be formed.

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

The dynamic friction coefficient of the transparent conductive layer against the transparent conductive layer is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. The smaller the dynamic friction coefficient of the transparent conductive layer against the transparent conductive layer, the more preferable it is, and the lower limit is, for example, 0.05. Within this range, a transparent conductive film that is unlikely to cause poor conductivity even when contact occurs with the transparent conductive layer can be obtained. The "dynamic friction coefficient of the transparent conductive layer against the transparent conductive layer" refers to the dynamic friction coefficient between the transparent conductive layer of the transparent conductive film and a transparent conductive layer of the same composition as the transparent conductive layer of the transparent conductive film. In this specification, the dynamic friction coefficient is measured in accordance with JIS K7125:1999, with a measurement load of 100 g, a measurement speed of 1 mm/s, and a measurement distance of 30 mm.

In one embodiment, the dynamic friction coefficient when the transparent conductive layer and the surface opposite the transparent conductive layer are in contact with each other is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. The smaller the dynamic friction coefficient when the transparent conductive layer and the surface opposite the transparent conductive layer are in contact with each other, the more preferable it is, but the lower limit is, for example, 0.05. The "surface opposite the transparent conductive layer" means the outermost surface opposite the surface of the transparent conductive layer to be measured, based on the substrate. Therefore, when the transparent conductive film has a configuration of transparent conductive layer A/substrate/transparent conductive layer A, the "dynamic friction coefficient when the transparent conductive layer and the surface opposite the transparent conductive layer are in contact with each other" is the dynamic friction coefficient when transparent conductive layers (transparent conductive layer A and transparent conductive layer A) are in contact with each other, and is synonymous with the "dynamic friction coefficient of the transparent conductive layer against the transparent conductive layer". In addition, when the transparent conductive film has a transparent conductive layer/substrate structure, the "dynamic friction coefficient when the transparent conductive layer is brought into contact with the surface opposite the transparent conductive layer" is the dynamic friction coefficient when the transparent conductive layer is brought into contact with the substrate. If the dynamic friction coefficient when the transparent conductive layer is brought into contact with the surface opposite the transparent conductive layer is within the above range, the occurrence of poor conductivity can be significantly prevented when the transparent conductive film is laminated or when the transparent conductive film is formed into a roll.

In one embodiment, the transparent conductive layer is patterned. Any suitable method may be adopted as the patterning method depending on the form of the transparent conductive layer. The shape of the pattern of the transparent conductive layer may be any suitable shape depending on the application. For example, the patterns described in JP-T-2011-511357, JP-A-2010-164938, JP-A-2008-310550, JP-T-2003-511799, and JP-T-2010-541109 may be mentioned. After the transparent conductive layer is formed on the substrate, it may be patterned using any suitable method depending on the form of the transparent conductive layer.

As the metal fibers, metal nanowires can be preferably used. The metal nanowires are conductive materials made of metal, shaped like needles or threads, and have a diameter on the order of nanometers. The metal nanowires may be straight or curved. If a transparent conductive layer made of metal nanowires is used, the metal nanowires form a mesh and are joined together to form good electrical conduction paths, resulting in a transparent conductive film with low electrical resistance.

The ratio of the thickness d to the length L of the metal nanowire (aspect ratio: L/d) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 10,000. By using metal nanowires with such a large aspect ratio, the metal nanowires can be well crossed, and high conductivity can be achieved with a small amount of metal nanowires. As a result, a transparent conductive film with high light transmittance can be obtained. In this specification, the "thickness of the metal nanowire" means the diameter when the cross section of the metal nanowire is circular, the short axis when the cross section is elliptical, and the longest diagonal when the cross section is polygonal. The thickness and length of the metal nanowire can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the 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. Within this range, a transparent conductive layer with high light transmittance can be formed.

The length of the 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.

As the metal constituting the metal nanowire, any suitable metal may be used as long as it is a metal with high electrical conductivity. Examples of the metal constituting the metal nanowire include silver, gold, copper, nickel, etc. Materials obtained by plating these metals (e.g., gold plating) may also be used. The metal nanowire is preferably made of one or more metals selected from the group consisting of gold, platinum, silver, and copper. In one embodiment, the metal nanowire is a silver nanowire.

As the method for producing the metal nanowires, any suitable method can be adopted. For example, there is a method of reducing silver nitrate in a solution, a method of applying a voltage or current from the tip of a probe to the surface of a precursor, drawing out the metal nanowires at the tip of the probe, and continuously forming the metal nanowires. In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by reducing a silver salt such as silver nitrate in the liquid phase in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Silver nanowires of uniform size can be mass-produced, for example, according to the methods described in Xia, Y. et al., Chem. Mater. (2002), 14, 4736-4745, and Xia, Y. et al., Nano letters (2003) 3(7), 955-960.

The content of the metal nanowires in the transparent conductive layer is preferably 80% by weight or less, based on the total weight of the transparent conductive layer. Within this range, a transparent conductive layer with a small dynamic friction coefficient can be formed. The content of the metal nanowires in the transparent conductive layer is more preferably 30% by weight to 75% by weight, more preferably 30% by weight to 65% by weight, and even more preferably 45% by weight to 65% by weight, based on the total weight of the transparent conductive layer. Within this range, a transparent conductive film with excellent electrical conductivity and light transparency can be obtained.

Any suitable polymer may be used as the polymer constituting the polymer matrix. Examples of the polymer include acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyl toluene, polyvinyl xylene, polyimide, polyamide, and polyamideimide; polyurethane polymers; epoxy polymers; polyolefin polymers; acrylonitrile-butadiene-styrene copolymers (ABS); cellulose; silicon polymers; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; and fluorine-based polymers. Preferably, a curable resin (preferably an ultraviolet-curable resin) composed of a polyfunctional acrylate such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), or trimethylolpropane triacrylate (TMPTA) is used.

The density of the transparent conductive layer is preferably 1.3 g/cm ³ to 10.5 g/cm ³ , and more preferably 1.5 g/cm ³ to 3.0 g/cm ^3. Within such a range, a transparent conductive film having excellent electrical conductivity and light transparency can be obtained.

The transparent conductive layer can be formed by applying a conductive layer-forming composition containing metal fibers (e.g., metal nanowires) to a substrate (or a laminate of the substrate and another layer) and then drying the applied layer. The conductive layer-forming composition may contain a resin material that forms a polymer matrix. Alternatively, the resin material that forms the polymer matrix may be prepared separately from the conductive layer-forming composition, and after applying and drying the conductive layer-forming composition, a resin material (polymer composition, monomer composition) may be applied onto the layer composed of metal fibers, and then the applied layer of the resin material may be dried or cured to form a transparent conductive layer.

The conductive layer forming composition may contain any suitable solvent in addition to metal fibers (e.g., metal nanowires). The conductive layer forming composition may be prepared as a dispersion of metal fibers (e.g., metal nanowires). Examples of the solvent include water, alcohol-based solvents, ketone-based solvents, ether-based solvents, hydrocarbon-based solvents, aromatic solvents, and the like. From the viewpoint of reducing the environmental load, it is preferable to use water. The conductive layer forming composition may further contain any suitable additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of metal fibers (e.g., metal nanowires), a surfactant that prevents aggregation of metal fibers (e.g., metal nanowires), and the like. The type, number, and amount of the additive used may be appropriately set depending on the purpose.

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

Any appropriate method may be used as a method for applying the conductive layer-forming composition. Examples of the application method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, intaglio printing, and gravure printing. Any appropriate drying method (e.g., natural drying, air drying, heat drying) may be used as a method for drying the applied layer. For example, in the case of heat drying, the drying temperature is typically 50°C to 200°C, and preferably 80°C to 150°C. The drying time is typically 1 to 10 minutes.

The polymer solution contains the polymer that constitutes the polymer matrix, or a precursor of the polymer (a monomer that constitutes the polymer).

The polymer solution may contain a solvent. Examples of the solvent contained in the polymer solution include alcohol-based solvents, ketone-based solvents, tetrahydrofuran, hydrocarbon-based solvents, and aromatic solvents. The solvent is preferably volatile. The boiling point of the solvent is preferably 200°C or less, more preferably 150°C or less, and even more preferably 100°C or less.

C. Substrate The substrate is typically made of any suitable resin. Examples of the resin constituting the substrate include cycloolefin resin, polyimide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyethylene terephthalate resin, and polyethylene naphthalate resin. Cycloolefin resin is preferably used. If a substrate made of cycloolefin resin is used, a transparent conductive film having excellent flexibility can be obtained.

As the cycloolefin resin, for example, polynorbornene can be preferably used. Polynorbornene refers to a (co)polymer obtained by using a norbornene-based monomer having a norbornene ring as part or all of the starting material (monomer). Various products of the polynorbornene are commercially available. Specific examples include "ZEONEX" and "ZEONOR" manufactured by Zeon Corporation, "Arton" manufactured by JSR Corporation, "TOPUS" manufactured by TICONA, and "APEL" manufactured by Mitsui Chemicals, Inc.

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 in this range, deterioration during the formation of the transparent conductive laminate can be prevented.

The thickness of the 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.

The total light transmittance of the above substrate is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. If the total light transmittance is within this range, a transparent conductive film suitable for use in a touch panel or the like can be obtained.

The above-mentioned base material may further contain any suitable additives as necessary. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. The types and amounts of additives used may be appropriately set depending on the purpose.

If necessary, the substrate may be subjected to various surface treatments. Any suitable method may be used for the surface treatment depending on the purpose. Examples of such methods include low-pressure 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 the surface of the transparent substrate hydrophilic. By making the substrate hydrophilic, the processability is excellent when applying a composition for forming a transparent conductive layer prepared from an aqueous solvent. In addition, a transparent conductive film having excellent adhesion between the substrate and the transparent conductive layer can be obtained.

D. Metal Layer The metal layer is comprised of any suitable metal, preferably a conductive metal such as silver, gold, copper, nickel, etc. In one embodiment, the metal layer is comprised of copper.

The metal layer can be formed by any suitable method. The metal layer can be formed by a dry process such as vapor deposition, sputtering, or CVD, or a wet process such as plating, etc.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Production Example 1]
(Production of Metal Nanowires)
In a reaction vessel equipped with a stirrer, 5 ml of anhydrous ethylene glycol and 0.5 ml of anhydrous ethylene glycol solution of PtCl2 (concentration: 1.5×10-4 mol/L) were added at 160°C. After 4 minutes, 2.5 ml of anhydrous ethylene glycol solution of AgNO3 (concentration: 0.12 mol/l) and 5 ml of anhydrous ethylene glycol solution of polyvinylpyrrolidone (MW: 55000) (concentration: 0.36 mol/l) were simultaneously added dropwise to the resulting solution over 6 minutes. After this dropwise addition, the mixture was heated to 160°C for 1 hour or more to react until _AgNO3 was completely reduced, producing silver nanowires. Next, acetone was added to the reaction mixture containing the silver nanowires obtained as described above until the volume of the reaction mixture was 5 times that of the reaction mixture, and the reaction mixture was centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires. The silver nanowires (concentration: 0.2% by weight) and pentaethylene glycol dodecyl ether (concentration: 0.1% by weight) were dispersed in pure water to prepare a silver nanowire ink.

[Example 1]
The silver nanowire ink obtained in Production Example 1 was applied onto a substrate (cycloolefin film) using a wire bar so that the resistivity after film formation would be 50 Ω/□, and the film was formed by heating at 120° C. for 2 minutes.
Furthermore, a coating solution a was prepared by diluting a photocurable resin mainly composed of urethane acrylate with a mixed solvent of isopropanol (IPA) and diacetone alcohol (DAA) (mixing ratio (by weight) IPA:DAA = 8:2) to a solid content concentration of 1.5%, and this was applied to the silver nanowire ink-coated surface using a spin coater so that the dry film thickness would be 70 nm. After heating at 80°C for 1 minute, the coating solution was irradiated with ultraviolet rays from a high-pressure mercury lamp with an accumulated exposure amount of 450 mJ/ ^cm2 to form a transparent conductive layer A, and a transparent conductive film A consisting of the substrate/transparent conductive layer A was obtained.
The transparent conductive film A was subjected to the following evaluations.
(1) Dynamic friction coefficient against transparent conductive layer A Using a product named "TSf-503" manufactured by Kyowa Interface Science Co., Ltd., the dynamic friction coefficient was measured in accordance with JIS K7125:1999 by sliding transparent conductive layer A against transparent conductive layer A under the conditions of contact side sample (transparent conductive layer A) size: 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 a product named "TSf-503" manufactured by Kyowa Interface Science Co., Ltd., the friction coefficient at the start of sliding (static friction coefficient) was measured in accordance with JIS K7125:1999 under the conditions of a sample (transparent conductive layer A) size on the contact side: 1 cm□, a measurement load: 100 g, a measurement speed: 1 mm/s, a measurement distance: 30 mm, and a measurement temperature: 23°C.
(3) Rate of Increase in Resistance Value The transparent conductive layers A were caused to slide against each other once at a distance of 3 cm under the same conditions as those used in the measurement of the dynamic friction coefficient, except that the load was 300 g.
The surface resistance of the transparent conductive layer was measured for the above-mentioned rubbed area and other areas using a non-contact surface resistance measuring device (manufactured by NAPSON, product name "EC-80", sheet resistance measurement mode, room temperature: 26°C).
The rate of increase in resistance due to sliding was calculated by the formula: (surface resistance of the sliding area/surface resistance of the area other than the sliding area).
(4) Arithmetic mean roughness Ra of transparent conductive layer A
The arithmetic mean roughness Ra of the surface of the transparent conductive layer A was measured in an area of 5 μm×5 μm using a scanning probe microscope “Nanoscope IV” AFM tapping mode manufactured by Veeco Instruments.

[Reference example 1-1]
A transparent conductive film A was obtained in the same manner as in Example 1.
(1a) Dynamic friction coefficient against copper film on transparent conductive layer A Separately, a transparent conductive film A was obtained in the same manner as in Example 1. A copper film was formed by sputtering on the transparent conductive layer A of the obtained transparent conductive film A so as to have a thickness of 100 nm, thereby obtaining a copper film-attached transparent conductive film. Using this copper film-attached transparent conductive film as a sample on the contact side, the transparent conductive layer A was slid against the copper film on the transparent conductive layer A in the same manner as in (1) above, and the dynamic friction coefficient was measured.
(2a) Static Friction Coefficient Separately, a transparent conductive film A was obtained in the same manner as in Example 1. A copper film was formed by sputtering on the transparent conductive layer A of the obtained transparent conductive film A to a thickness of 100 nm, to obtain a copper-film-attached transparent conductive film. Using this copper-film-attached transparent conductive film as a sample on the contact side, the transparent conductive layer A was slid against the copper film on the transparent conductive layer A in the same manner as in (2) above, and the coefficient of friction (static friction coefficient) at the start of sliding was measured.
(3a) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer A and the copper film on the transparent conductive layer A were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(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 measured by the same method as in (4) above.

[Reference example 1-2]
A transparent conductive film A was obtained in the same manner as in Example 1.
(1b) Dynamic friction coefficient against transparent conductive layer d The silver nanowire ink obtained in Production Example 1 was applied to a substrate (cycloolefin film) using a wire bar so that the resistivity after film formation would be 50 Ω/□, and a film was formed by heating at 120° C. for 2 minutes.
Furthermore, a coating solution a was prepared by diluting a photocurable resin mainly composed of urethane acrylate with methyl isobutyl ketone to a solid content concentration of 1.5%, and this was applied to the silver nanowire ink-coated surface using a spin coater so that the dry film thickness would be 70 nm. After heating at 80° C. for 1 minute, the coating solution was irradiated with ultraviolet rays from a high-pressure mercury lamp with an integrated exposure amount of 450 mJ/ ^cm2 to form a transparent conductive layer d, and a transparent conductive film d consisting of the substrate/transparent conductive layer d was obtained.
The transparent conductive film d was used as the sample on the contact side, and the transparent conductive layer A and the transparent conductive layer d were slid against each other in the same manner as in (1) above to measure the dynamic friction coefficient.
(2b) Static Friction Coefficient Using transparent conductive film d as the sample on the contact side, the transparent conductive layer A and the transparent conductive layer d were slid against each other in the same manner as in (2) above, and the initial friction coefficient (static friction coefficient) was measured.
(3b) Rate of Increase in Resistance Value Using the same method as in (3) above, the transparent conductive layer A and the transparent conductive layer d were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4b) Arithmetic mean roughness Ra of transparent conductive layer d
The arithmetic mean roughness Ra of the transparent conductive layer d was measured by the same method as in (4) above.

[Reference example 1-3]
A transparent conductive film A was obtained in the same manner as in Example 1.
(1c) Dynamic Friction Coefficient Against Cycloolefin Film Using a cycloolefin film (manufactured by Zeon Corporation, product name "ZF16") as a sample on the contact side, the transparent conductive layer A and the cycloolefin film were slid against each other in the same manner as in (1) above to measure the dynamic friction coefficient.
(2c) Static Friction Coefficient A cycloolefin film (manufactured by Zeon Corporation, product name "ZF16") was used as a sample on the contact side, and the transparent conductive layer A and the cycloolefin film were slid against each other in the same manner as in (2) above, to measure the initial friction coefficient (static friction coefficient).
(3c) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer A and the cycloolefin film were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4c) Arithmetic mean roughness Ra of cycloolefin film
The arithmetic mean roughness Ra of the cycloolefin film was measured by the same method as in (4) above.

[Reference example 1-4]
A transparent conductive film A was obtained in the same manner as in Example 1.
(1d) Dynamic Friction Coefficient Against PET Film Using a PET film (manufactured by KOLON Industry, product name "CE900") as a sample on the contact side, the transparent conductive layer A and the PET film were slid against each other in the same manner as in (1) above to measure the dynamic friction coefficient.
(2d) Static Friction Coefficient Using a PET film (manufactured by KOLON Industry, product name "CE900") as a sample on the contact side, the transparent conductive layer A and the PET film were slid against each other in the same manner as in (2) above, and the initial friction coefficient (static friction coefficient) was measured.
(3d) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer A and the PET film were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4d) Arithmetic mean roughness Ra of PET film
The arithmetic mean roughness Ra of the PET film was measured by the same method as in (4) above.

[Reference example 1-5]
A transparent conductive film A was obtained in the same manner as in Example 1.
(1e) Dynamic Friction Coefficient Against Acrylic Film Using an acrylic film (manufactured by Toyo Kohan Co., Ltd., product name "HX-40-UF") as a sample on the contact side, the transparent conductive layer A and the acrylic film were slid against each other in the same manner as in (1) above to measure the dynamic friction coefficient.
(2e) Static Friction Coefficient Using an acrylic film (manufactured by Toyo Kohan Co., Ltd., product name "HX-40-UF") as a sample on the contact side, the transparent conductive layer A and the acrylic film were slid against each other in the same manner as in (2) above, and the coefficient of friction at the start of sliding (static friction coefficient) was measured.
(3e) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer A and the acrylic film were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4e) Arithmetic mean roughness Ra of acrylic film
The arithmetic mean roughness Ra of the acrylic film was measured by the same method as in (4) above.

[Example 2]
A transparent conductive film B composed of a substrate and a transparent conductive layer B was obtained in the same manner as in Example 1, except that the dry film thickness of the coating solution a was set to 100 nm.
The transparent conductive film B was subjected to the following evaluations.
(1B) Dynamic friction coefficient against transparent conductive layer B Using a product named "TSf-503" manufactured by Kyowa Interface Science Co., Ltd., the dynamic friction coefficient was measured in accordance with JIS K7125:1999 by sliding transparent conductive layer B against transparent conductive layer B under the conditions of contact side sample (transparent conductive layer B) size: 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 a product named "TSf-503" manufactured by Kyowa Interface Science Co., Ltd., the friction coefficient at the start of sliding (static friction coefficient) was measured in accordance with JIS K7125:1999 under the conditions of a sample (transparent conductive layer B) size on the contact side: 1 cm□, a measurement load: 100 g, a measurement speed: 1 mm/s, a measurement distance: 30 mm, and a measurement temperature: 23°C.
(3B) Rate of Increase in Resistance Value The transparent conductive layers B were caused to slide against each other once at a distance of 3 cm under the same conditions as those for measuring the dynamic friction coefficient, except that the load was 300 g.
The surface resistance of the transparent conductive layer was measured for the above-mentioned rubbed area and other areas using a non-contact surface resistance measuring device (manufactured by NAPSON, product name "EC-80", sheet resistance measurement mode, room temperature: 26°C).
The rate of increase in resistance due to sliding was calculated by the formula: (surface resistance of the sliding area/surface resistance of the area other than the sliding area).
(4B) Arithmetic mean roughness Ra of transparent conductive layer B
The arithmetic mean roughness Ra of the surface of the transparent conductive layer B was measured in an area of 5 μm×5 μm using a scanning probe microscope “Nanoscope IV” AFM tapping mode manufactured by Veeco Instruments.

[Comparative Example 1]
A silver nanowire layer was formed in the same manner as in Example 1. Furthermore, a silane coupling agent was added to a photocurable resin mainly composed of urethane acrylate, and the coating liquid c was prepared by diluting the resin with methyl isobutyl ketone to a solid content concentration of 1.5%, and the coating liquid c was applied to the silver nanowire ink-coated surface using a spin coater so that the dry film thickness was 70 nm, and the coating was heated at 80° C. for 1 minute, and then irradiated with ultraviolet light from a high-pressure mercury lamp at an integrated exposure amount of 450 mJ/cm ² to form a transparent conductive layer C, thereby obtaining a transparent conductive film C consisting of the substrate/transparent conductor C.
(1f) Dynamic Friction Coefficient Against Transparent Conductive Layer d Using transparent conductive layer C as the sample on the contact side, transparent conductive layer C was slid against transparent conductive layer C in the same manner as in (1) above to measure the dynamic friction coefficient.
(2g) Static Friction Coefficient Using the transparent conductive layer C as the sample on the contact side, the transparent conductive layer C was slid against the transparent conductive layer C in the same manner as in (2) above, and the initial friction coefficient (static friction coefficient) was measured.
(3g) Rate of Increase in Resistance Value: In the same manner as in (3) above, the transparent conductive layer C and the cycloolefin film were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4g) Arithmetic mean roughness Ra of transparent conductive layer d
The arithmetic mean roughness Ra of the transparent conductive layer C was measured by the same method as in (4) above.

[Comparative Example 2]
A transparent conductive film d consisting of a substrate and a transparent conductive layer d was obtained in the same manner as in Reference Example 1-2.
(1g) Dynamic Friction Coefficient Against Transparent Conductive Layer d Using transparent conductive layer d as the sample on the contact side, transparent conductive layer d was slid against transparent conductive layer d in the same manner as in (1) above to measure the dynamic friction coefficient.
(2g) Static Friction Coefficient Using transparent conductive layer d as the sample on the contact side, transparent conductive layer d was slid against transparent conductive layer d in the same manner as in (2) above, and the coefficient of friction at the start of sliding (static friction coefficient) was measured.
(3g) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer d and the cycloolefin film were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(4g) Arithmetic mean roughness Ra of transparent conductive layer d
The arithmetic mean roughness Ra of the transparent conductive layer d was measured by the same method as in (4) above.

[Comparative Reference Example 2-1]
In the same manner as in Comparative Example 2, a transparent conductive film d was obtained.
(1h) Dynamic friction coefficient with respect to the copper film on the transparent conductive layer d Separately, a transparent conductive film d was obtained in the same manner as in Comparative Example 2. A copper film was sputter-formed to a thickness of 100 nm on the transparent conductive layer d of the obtained transparent conductive film d, to obtain a transparent conductive film with a copper film. The sample on the contact side was the transparent conductive film with a copper film, and the dynamic friction coefficient was measured by sliding the transparent conductive layer d against the copper film on the transparent conductive layer d in the same manner as in (1) above.
(2h) Static Friction Coefficient Using the above-mentioned copper-film-attached transparent conductive film as the sample on the contact side, the transparent conductive layer d and the copper film on the transparent conductive layer d were slid against each other in the same manner as in (2) above, and the initial friction coefficient (static friction coefficient) was measured.
(3h) Rate of Increase in Resistance Value In the same manner as in (3) above, the transparent conductive layer d and the copper film on the transparent conductive layer d were caused to slide against each other, and the rate of increase in resistance value due to the sliding was measured.
(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 measured by the same method as in (4) above.

The evaluation results of the above-mentioned Examples, Reference Examples, Comparative Examples, and Comparative Reference Examples are shown in Table 1. In addition, the sample on the contact side in terms of the dynamic friction coefficient and resistance increase rate is indicated in the table as "layer in contact with the transparent conductive layer."

As is clear from Table 1, according to the present invention, by specifying the arithmetic mean surface roughness Ra of the transparent conductive layer, it is possible to provide a transparent conductive film that is unlikely to suffer from poor conductivity due to contact, even though it has a conductive layer that contains metal fibers. As shown in the reference examples, such a transparent conductive film is able to suppress an increase in resistance value even when it comes into contact with and slides against various films, etc.

10: Substrate 20: Transparent conductive layer 30: Metal layer 100, 200, 300: Transparent conductive film

Claims (4)

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 nanowires present in the polymer matrix;
the transparent conductive layer has an arithmetic mean surface roughness Ra of 3 nm to 5 nm ;
the content of the metal nanowires in the transparent conductive layer is 30% by weight to 80% by weight based on the total weight of the transparent conductive layer;
The transparent conductive layer has a thickness of 50 nm to 100 nm;
a dynamic friction coefficient of the transparent conductive layer with respect to the transparent conductive layer is 1.5 or less;
Transparent conductive film. The transparent conductive film according to claim 1, wherein the metal nanowires are silver nanowires. Further comprising a metal layer;
the transparent conductive layer, the substrate, and the metal layer are disposed in this order;
The transparent conductive film according to claim 1 or 2. The transparent conductive film of claim 3 , wherein the metal layer is made of copper.