JP2022108459A - transparent conductive film - Google Patents

Abstract

To provide a transparent conductive film that includes metal nanowires and has excellent conductivity and transparency.SOLUTION: The present invention is a transparent conductive film comprising a substrate and a transparent conductive layer arranged on one side of the substrate, wherein the transparent conductive layer includes metal nanowires and the relationship between the amount x(g/m2) of metal nanowires in the transparent conductive layer and the conductivity y(1/Ω) of the transparent conductive film satisfies formula (1). Formula (1): y=a×x (in formula (1), a is 0.77 or more).SELECTED DRAWING: Figure 1

Description

The present invention relates to transparent conductive films.

Conventionally, in an image display device having a touch sensor, a transparent conductive film obtained by forming a metal oxide layer such as ITO (indium-tin composite oxide) on a transparent resin film is often used as an electrode of the touch sensor. ing. However, the transparent conductive film having this metal oxide layer tends to lose its conductivity when bent, and is difficult to use for applications requiring flexibility such as flexible displays.

On the other hand, a transparent conductive film containing metal nanowires is known as a highly flexible transparent conductive film. A metal nanowire is a wire-like conductive substance with a nanometer-sized diameter. In the transparent conductive film composed of metal nanowires, the metal nanowires form a mesh, so that a small amount of metal nanowires forms a good electrical conduction path, and openings are formed in the gaps of the mesh. formed to achieve high light transmittance. Also in transparent conductive films containing such metal nanowires, improvement in conductivity, which is essentially required for conductive films, is being investigated.

Japanese Patent Publication No. 2009-505358 Patent No. 6199034

The present invention has been made to solve the above problems, and an object of the present invention is to provide a transparent conductive film containing metal nanowires and having excellent conductivity and transparency.

A transparent conductive film of the present invention is a transparent conductive film comprising a substrate and a transparent conductive layer disposed on one side of the substrate, wherein the transparent conductive layer contains metal nanowires, and the transparent conductive layer contains metal nanowires. The relationship between the amount x (g/m ² ) of the metal nanowires in the conductive layer and the conductivity y (1/Ω) of the transparent conductive film is represented by the following formula (1).
y=a×x (1)
In formula (1), a is 0.77 or more.
In one embodiment, the transparent conductive film has a haze value of 20% or less.
In one embodiment, the transparent conductive film has a surface resistance value of 0.1Ω/□ to 1000Ω/□.
In one embodiment, the amount x (g/m ² ) of metal nanowires in the transparent conductive layer is 0.005 g/m ² to 0.05 g/m ² .

ADVANTAGE OF THE INVENTION According to this invention, the transparent conductive film which contains a metal nanowire and is excellent in electroconductivity and transparency can be provided.

1 is a schematic cross-sectional view of a transparent conductive film obtained by a manufacturing method according to one embodiment of the present invention; FIG.

A. Transparent Conductive Film FIG. 1 is a schematic cross-sectional view of a transparent conductive film obtained by a manufacturing method according to one embodiment of the present invention. A transparent conductive film 100 includes a substrate 10 and a transparent conductive layer 20 disposed on one side of the substrate 10 . Transparent conductive layer 20 includes metal nanowires (not shown).

The surface resistance value of the transparent conductive film is preferably 0.1 Ω/square to 1000 Ω/square, more preferably 0.5 Ω/square to 300 Ω/square, and still more preferably 1 Ω/square to 200 Ω/square. 1 Ω/□ to 150 Ω/□, and most preferably 20 Ω/□ to 100 Ω/□. The surface resistance value can be measured by "Automatic resistivity measurement system MCP-S620 type/MCP-S521 type" manufactured by Mitsubishi Chemical Analytech.

The haze value of the transparent conductive film is preferably 20% or less, more preferably 10% or less, still more preferably 0.1% to 5%, still more preferably 0.1% to 3%. and particularly preferably 0.1% to 1%.

The total light transmittance of the transparent conductive film is preferably 30% or more, more preferably 35% or more, and particularly preferably 40% or more.

(Transparent conductive layer)
As noted above, the transparent conductive layer includes metal nanowires.

The relationship between the amount x (g/m ² ) of metal nanowires in the transparent conductive layer and the conductivity y (1/Ω) of the transparent conductive film is represented by the following formula (1):
y=a×x (1)
In formula (1), a is 0.77 or more. In the present invention, the above relationship between the amount x (g/m ² ) of metal nanowires and the conductivity y (1/Ω) makes it possible to obtain a transparent conductive film with remarkably excellent conductivity. . The transparent conductive film of the present invention has high conductivity while using a relatively small amount of metal nanowires. Such a transparent conductive film is very advantageous in that both high conductivity and transparency (low haze) can be achieved. Such a transparent conductive film can be produced by applying a composition for forming a transparent conductive layer to form a coating layer, leaving the coating layer for a predetermined period of time, and then carrying out the following air blowing step, as described later. ,Obtainable. By allowing the coating layer to stand for a predetermined period of time, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the contact points between the metal nanowires increase.

In the above formula (1), a is preferably 0.79 or more, more preferably 0.8 or more, still more preferably 0.85 or more, particularly preferably 0.88 or more, and further Preferably it is 0.9 or more. Within such a range, the above effects are more pronounced. A larger value of a is more preferable, but its upper limit is, for example, 2.0. The greater the amount of silver, the higher the electrical conductivity, but the haze increases accordingly and the transparency is impaired. The amount of metal nanowires x (g/m ² ) is the weight of metal nanowires present per m ² of the transparent conductive layer. Conductivity is the reciprocal of the surface resistance value.

The amount x (g/m ² ) of metal nanowires in the transparent conductive layer is preferably 0.005 g/m ² to 0.05 g/m ² , more preferably 0.008 g/m ² to 0.03 g/m ² , still more preferably 0.01 g/m ² to 0.025 g/m ² , particularly preferably 0.01 g/m ² to 0.02 g/m ² .

In one embodiment, the transparent conductive layer further comprises a polymer matrix. In this embodiment, metal nanowires are present in a polymer matrix. In a transparent conductive layer composed of a polymer matrix, the polymer matrix protects the metal nanowires. As a result, corrosion of the metal nanowires is prevented, and a transparent conductive film with superior durability can be obtained.

The thickness of the transparent conductive layer is preferably 2 μm to 10 μm, more preferably 3 μm to 9 μm, still more preferably 4 μm to 8 μm.

The content of the metal nanowires in the transparent conductive layer is preferably 0.1 to 50 parts by weight, more preferably 0.1 to 50 parts by weight, with respect to 100 parts by weight of the binder resin constituting the transparent conductive layer. 30 parts by weight. Within such a range, a transparent conductive film having excellent conductivity and light transmittance can be obtained.

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

A metal nanowire is a conductive substance that is made of metal, has a needle-like or thread-like shape, and has a nanometer-sized diameter. The metal nanowires may be straight or curved. When a transparent conductive layer composed of metal nanowires is used, the metal nanowires form a mesh, so that even a small amount of metal nanowires can form a good electrical conduction path. A conductive film can be obtained. Furthermore, since the metal nanowires are mesh-like, openings are formed in the gaps of the meshes, and a transparent conductive film with high light transmittance can be obtained.

The ratio of the thickness d to the length L of the metal nanowires (aspect ratio: L/d) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 10,000. When metal nanowires having a large aspect ratio are used in this manner, the metal nanowires can cross each other satisfactorily, and a small amount of metal nanowires can exhibit high conductivity. 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 minor axis when the metal nanowire is elliptical, and the polygonal In some cases it means the longest diagonal. The thickness and length of metal nanowires can be confirmed with 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, most preferably 10 nm to 50 nm. Within such a 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 10 μm to 500 μm, particularly preferably 10 μm to 100 μm. Within such a range, a transparent conductive film with high conductivity can be obtained.

Any appropriate metal can be used as the metal constituting the metal nanowires as long as it is a conductive metal. Examples of metals forming the metal nanowires include silver, gold, copper, and nickel. Also, materials obtained by subjecting these metals to plating (for example, gold plating) may be used. Silver, copper or gold is preferred, and silver is more preferred, from the viewpoint of conductivity.

Any appropriate method can be adopted as a method for producing the metal nanowires. Examples include a method of reducing silver nitrate in a solution, a method of applying voltage or current from the tip of a probe to the surface of a precursor, pulling out metal nanowires at the tip of the probe, and forming the metal nanowires continuously. . In the method of reducing silver nitrate in solution, silver nanowires can be synthesized by liquid phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires are described, for example, in Xia, Y.; et al. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y.; et al. , Nano letters (2003) 3(7), 955-960, mass production is possible.

(Base material)
Any appropriate material can be used as the material constituting the base material. Specifically, for example, polymeric substrates such as films and plastics substrates are preferably used. This is because the smoothness of the base material and the wettability with respect to the composition for forming a transparent conductive layer are excellent, and the productivity can be greatly improved by continuous production using rolls.

The material constituting the substrate is typically a polymer film containing a thermoplastic resin as a main component. Examples of thermoplastic resins include polyester-based resins; cycloolefin-based resins such as polynorbornene; acrylic-based resins; polycarbonate resins; and cellulose-based resins. Among them, polyester resins, cycloolefin resins and acrylic resins are preferable. These resins are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and the like. You may use the said thermoplastic resin individually or in combination of 2 or more types. Optical films used for polarizing plates, such as low retardation substrates, high retardation substrates, retardation plates, brightness enhancement films, etc., can also be used as substrates.

The thickness of the substrate is preferably 20 μm to 200 μm, more preferably 30 μm to 150 μm.

The total light transmittance of the substrate is preferably 30% or more, more preferably 35% or more, and still more preferably 40% or more.

B. In one embodiment of the method for producing a transparent conductive film, the method for producing a transparent conductive film of the present invention comprises applying a composition for forming a transparent conductive layer containing metal nanowires to a substrate to form a coating layer. a step of leaving the coating layer to stand for a predetermined period of time; and a blowing step of blowing air to the coating layer after the leaving step. According to such a manufacturing method, the above transparent conductive film, that is, a transparent conductive film comprising a substrate and a transparent conductive layer disposed on one side of the substrate is obtained. The manufacturing method may include any appropriate other process in addition to the coating process and the air blowing process. In one embodiment, the manufacturing method may further include a drying step of drying the coating layer after the blowing step. In another embodiment, the blowing step is a step capable of drying the coating layer, and the transparent conductive layer is formed through the blowing step.

In one embodiment, the manufacturing method can be performed while conveying the substrate. Typically, the coating step, the standing step, and the air blowing step (and, if necessary, other steps such as a drying step) are performed while the substrate in a roll state is paid out and conveyed, A long transparent conductive film is formed comprising a substrate and a transparent conductive layer disposed on one side of the substrate. In one embodiment, the transparent conductive film is rolled after formation.

Any appropriate method can be adopted as a method for conveying the substrate. For example, transportation by a transportation roll, transportation by a transportation belt, a combination thereof, and the like can be mentioned. The conveying speed is, for example, 5m/min to 50m/min.

(Coating process)
As described above, in the coating step, the composition for forming a transparent conductive layer containing metal nanowires is applied to the substrate by any appropriate method to form a coating layer. In one embodiment, a coating layer is formed by applying a composition for forming a transparent conductive layer containing metal nanowires to a long base material while conveying the base material.

The composition for forming a transparent conductive layer contains the metal nanowires. In one embodiment, a composition for forming a transparent conductive layer is prepared by dispersing metal nanowires in any appropriate solvent. Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, aromatic solvents and the like. Moreover, the composition for forming a transparent conductive layer may further contain additives such as a resin (binder resin), a conductive material other than the metal nanowires (for example, conductive particles), and a leveling agent. In addition, the composition for forming the transparent conductive layer contains a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a coloring agent, an antistatic agent, a compatibilizer, a cross-linking agent, and a thickening agent. Additives such as thickeners, inorganic particles, surfactants, and dispersants may be included.

The viscosity of the composition for forming a transparent conductive layer is preferably 5 mP·s/25°C to 300 mP·s/25°C, more preferably 10 mP·s/25°C to 100 mP·s/25°C. With such a range, the effect of the present invention becomes remarkable. The viscosity of the composition for forming a transparent conductive layer can be measured with a rheometer (eg, MCR302 manufactured by Anton Paar).

The dispersion concentration of the metal nanowires in the composition for forming a transparent conductive layer is preferably 0.01% by weight to 5% by weight. With such a range, the effect of the present invention becomes remarkable.

Any appropriate method can be adopted as a method for applying the composition for forming a transparent conductive layer. Examples of coating methods include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, intaglio printing, and gravure printing.

The basis weight of the coating layer is preferably 0.3 g/m ² to 30 g/m ² , more preferably 1.6 g/m ² to 16 g/m ² . Within such a range, the metal nanowires are well dispersed by air blowing in the air blowing step, and a transparent conductive film with smaller conductive anisotropy can be produced.

The thickness Ts of the coating layer in the coating step is preferably 10 μm to 50 μm, more preferably 13 μm to 40 μm, still more preferably 13 μm to 30 μm, and particularly preferably 13 μm to 20 μm. Within such a range, a transparent conductive film having particularly excellent conductivity can be obtained. The thickness Ts (hereinafter also referred to as the initial thickness Ts of the coating layer) means the thickness (wet thickness) of the coating layer immediately after the coating. The thickness Ts (wet thickness) of the coating layer can be measured by an optical interference film thickness gauge (for example, “Spectroscope FLAME-S” manufactured by Ocean Insight).

(Standing process)
The leaving step is, as described above, a step of leaving the coating layer to stand for a predetermined period of time. More specifically, it is a step of leaving the laminate structure including the substrate and the coating layer in an environment where the coating layer is at 25° C. or lower (preferably 20° C. to 25° C.) and no wind. In the present specification, the windless state refers to a state in which the wind speed (relative wind speed in the case of conveying the base material) is less than 0.5 m/s. In the present specification, the term "leave" means reducing the thickness of the coating layer under windless conditions, and includes an operation of reducing the thickness of the coating layer while transporting the laminated structure including the substrate and the coating layer. It is a concept.

The time for leaving the coating layer is, for example, 1 second to 300 seconds. The time for leaving the coating layer to stand corresponds to the time from the formation of the coating layer in the previous step to the start of air blowing in the subsequent step.

In the present invention, a transparent conductive film having excellent conductivity can be obtained by carrying out the next air blowing step after leaving the coating layer to stand for a predetermined time. A transparent conductive film obtained by the above production method, a transparent conductive film obtained by drying the coating layer without air blowing, or a transparent conductive film obtained by blowing air on the coating layer immediately after coating. By comparison, the transparent conductive film obtained by the above production method is superior in the conductivity per unit weight of the metal nanowires. According to the production method of the present invention, by allowing the coating layer to stand for a predetermined time, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the number of contact points between the metal nanowires increases. It is considered that the effect can be obtained.

The thickness of the coating layer after the standing step (thickness Tb of the coating layer when air blowing is started in the air blowing step) preferably exceeds 1 μm, more preferably 2 μm or more. That is, it is preferable to finish the standing step before the thickness of the coating layer reaches 1 μm or less (preferably less than 2 μm). By doing so, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the number of contact points between the metal nanowires can be increased.

In one embodiment, the standing time is determined based on the thickness Ts of the coating layer in the coating step and the thickness of the coating layer after the standing step (thickness Tb of the coating layer when air blowing is started in the air blowing step). be done. In one embodiment, the thickness Tb of the coating layer when air blowing is started in the air blowing step is 25% to 90%, more preferably 27% to 90% of the thickness Ts of the coating layer in the coating step. 89%, more preferably 30% to 88%. Within such a range, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the number of contact points between the metal nanowires increases, so the transparent conductive film has high conductivity per unit weight of the metal nanowires. can be obtained.

In one embodiment, the coating layer is preferably left to stand until the thickness of the coating layer becomes 2 μm to 12 μm thinner than the initial thickness Ts of the coating layer, and is 4 μm to 11 μm less than the initial thickness Ts of the coating layer. It is more preferable to leave the coating layer until it becomes thinner, and it is more preferable to leave the coating layer until it becomes thinner than the initial thickness Ts of the coating layer by 6 μm to 10 μm. It is preferable to leave the coated layer until the thickness is reduced by 6 μm to 9 μm. With such a range, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the number of contact points between the metal nanowires can be increased.

Further, when the initial thickness Ts of the coating layer is 10 μm to 13 μm, it is preferable to leave the coating layer until the thickness Tb of the coating layer reaches 2.5 μm to 9 μm, and until the thickness Tb of the coating layer reaches 3 μm to 5 μm. It is more preferable to leave the coating layer alone. Further, when the initial thickness Ts of the coating layer is more than 13 μm and less than 16 μm, it is preferable to leave the coating layer until the thickness Tb of the coating layer becomes 4 μm to 12 μm, and the thickness Tb of the coating layer becomes 5 μm to 7 μm. It is more preferable to leave the coating layer to stand. Further, when the initial thickness Ts of the coating layer exceeds 16 μm (preferably exceeding 16 μm and 30 μm or less, more preferably exceeding 16 μm and 20 μm or less), the coating layer is left to stand until the thickness Tb of the coating layer reaches 6 μm to 14 μm. More preferably, the coating layer is allowed to stand until the thickness Tb of the coating layer reaches 7 μm to 9 μm. With such a range, the flow of the metal nanowires in the coating layer can be preferably adjusted, and the number of contact points between the metal nanowires can be increased.

(Blowing process)
Air blowing to the coating layer can be performed by any appropriate method. In one embodiment, the applied layer can be blown with a blower positioned above (opposite to the substrate) and/or to the side of the applied layer. Let the direction of air blow be arbitrary suitable directions. For example, the air blowing direction may be such that it has a predetermined angle (eg, 10° to 170°) with respect to the coating layer surface, and the air is blown substantially parallel to the coating layer surface (eg, less than 10° with respect to the coating layer surface). good too. Alternatively, a spiral wind may be sent. The blowing direction can be adjusted, for example, by providing a blower with louvers and adjusting the direction of the louvers. In one embodiment, the blowing direction is defined by the opening direction of the louver. Moreover, when sending a spiral wind, a blower having a spiral wind direction plate at the air blow port can be used.

The wind speed of the wind is preferably 0.5 m/s to 10 m/s, more preferably 1 m/s to 5 m/s. Within this range, the metal nanowires are well dispersed, and a transparent conductive film with excellent conductivity can be produced. Also, a transparent conductive film having excellent surface smoothness and thickness uniformity can be obtained. The wind speed can be appropriately set according to the solvent or the like contained in the composition for forming a transparent conductive layer. When using the composition for forming a transparent conductive layer prepared with water, the wind speed is preferably 0.5 m/s to 10 m/s, more preferably 1 m/s to 5 m/s. In addition, in this specification, wind speed means the wind speed at the time of reaching a coating layer.

The temperature of the wind is preferably 10°C to 50°C, more preferably 15°C to 30°C. The wind speed can be appropriately set according to the solvent or the like contained in the composition for forming a transparent conductive layer. When the composition for forming a transparent conductive layer prepared with water is used, the temperature of the air is preferably 10°C to 50°C, more preferably 15°C to 30°C. In this specification, the temperature of the air means the temperature of the air when it reaches the coating layer.

The blowing time is preferably 1 to 10 minutes, more preferably 2 to 5 minutes. Within such a range, the metal nanowires are well dispersed, and a transparent conductive film with smaller conductive anisotropy can be produced. Specifically, the metal nanowires can be appropriately dispersed over the entire coating layer by determining the air-blown area so that the air-blowing time falls within the above range. Also, a transparent conductive film having excellent surface smoothness and thickness uniformity can be obtained.

In the air blowing process, air may be blown in multiple stages. For example, it may be divided into zones with different wind directions, wind speeds, temperatures, etc., and blowing may be carried out in stages.

Any suitable treatment may be performed after the blowing step. For example, when a composition for forming a transparent conductive layer containing a binder resin is used, curing treatment such as ultraviolet irradiation may be performed. Moreover, you may perform a drying process after a sending process. Examples of drying methods include oven heating and natural drying.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Evaluation methods in the examples are as follows. The thickness was measured by an optical interference type film thickness meter (“Spectroscope FLAME-S” manufactured by Ocean Insight).

(1) Surface resistance value, conductivity The surface resistance value (MD and TD surface resistance values) of the transparent conductive film was measured using a non-contact surface resistance meter trade name “EC-80” manufactured by Napson Co., Ltd. Measured by the current method. The measurement temperature was 23°C. Also, the reciprocal of the surface resistance value was obtained and used as the electrical conductivity.
^In addition, a ( ^{m 2} /Ω·g) was obtained.

(2) Haze value The haze value of the transparent conductive film was measured according to the method defined in JIS 7136 using a haze meter (manufactured by Murakami Color Science Laboratory, trade name "HN-150").

[Production Example 1] Preparation of composition for forming transparent conductive layer Chem. Mater. Silver nanowires were synthesized based on the method described in 2002, 14, 4736-4745.
In pure water, 0.2% by weight of the silver nanowires obtained above and 0.1% by weight of dodecyl-pentaethylene glycol were dispersed to obtain a composition for forming a transparent conductive layer. .

[Example 1]
A PET film (manufactured by Mitsubishi Plastics, trade name “S100”) was used as the base material. While transporting this substrate using a transport roll, the transparent conductive material prepared in Production Example 1 using a bar coater (manufactured by Daiichi Rika Co., Ltd., product name “Bar Coater No. 6”) on the substrate The layer-forming composition was applied to form a coating layer having a thickness (initial thickness Ts of the coating layer) of 13 μm (that is, the amount of metal nanowires per m ² x (g/m ² ) = 0.012 g/m ² ). After that, it was left to stand until the thickness of the coating layer (thickness Tb of the coating layer when air blowing was started in the air blowing step) reached 9.1 μm (that is, Tb/Ts=0.7) (leaving step). Next, air was blown from the center of the substrate to both ends in the direction from the inner side in the width direction to the both outer sides in the width direction. The angle formed by the substrate conveying direction and the air blowing direction (air blowing direction viewed from the side of the coating layer) shall be 90°, and the angle formed between the substrate conveying direction and the air blowing direction (air blowing direction viewed from the side of the coating layer). was set to 0°. The wind speed was set to 2 m/s, and the wind temperature was set to 25°C. Also, the blowing time (drying time) was set to 2 minutes.
The obtained transparent conductive film was subjected to the above evaluations (1) and (2). Table 1 shows the results.

[Examples 2-8, Comparative Examples 1-2]
Example except that the initial thickness Ts of the coating layer (resulting in the amount of metal nanowires x) and the thickness Tb of the coating layer when air blowing is started in the air blowing step (at the start of air blowing) are as shown in Table 1. A transparent conductive film was obtained in the same manner as in 1. The obtained transparent conductive film was subjected to the above evaluations (1) and (2). Table 1 shows the results.

[Comparative Example 3]
A PET film (manufactured by Mitsubishi Plastics, trade name “S100”) was used as the base material. While transporting this substrate using a transport roll, the transparent conductive material prepared in Production Example 1 using a bar coater (manufactured by Daiichi Rika Co., Ltd., product name “Bar Coater No. 6”) on the substrate The layer-forming composition was applied to form a coating layer having a thickness of 13 μm (that is, the amount of metal nanowires per 1 m ² x (g/m ² )=0.012 g/m ² ). After that, the substrate with the coating layer formed thereon was placed in an oven having an internal temperature of 100° C. for 2 minutes to obtain a transparent conductive film. The obtained transparent conductive film was subjected to the above evaluations (1) and (2). Table 1 shows the results.

As is clear from Table ¹ , according to the present invention, the above "y ⁼ A transparent conductive film in which high conductivity and low haze value are well-balanced by setting a (m ² /Ω·g) in a×x (1) to a specific value or more. can be obtained. Such a transparent conductive film can be obtained by manufacturing through a standing process. Further, by optimizing the thickness of the coating layer at the start of air blowing (by optimizing the standing time) according to the initial thickness of the coating layer, the above effect becomes more pronounced.

REFERENCE SIGNS LIST 10 base material 20 transparent conductive layer 100 transparent conductive film

Claims (4)

A transparent conductive film comprising a substrate and a transparent conductive layer disposed on one side of the substrate,
the transparent conductive layer comprises metal nanowires;
The relationship between the amount x (g/m ² ) of the metal nanowires in the transparent conductive layer and the conductivity y (1/Ω) of the transparent conductive film is represented by the following formula (1):
Transparent conductive film:
y=a×x (1)
In formula (1), a is 0.77 or more. 2. The transparent conductive film according to claim 1, which has a haze value of 20% or less. 3. The transparent conductive film according to claim 1, which has a surface resistance value of 0.1 Ω/□ to 1000 Ω/□. The transparent conductive film according to any one of claims 1 to 3, wherein the amount x (g/m ² ) of metal nanowires in the transparent conductive layer is 0.005g/m ² to 0.05g/m ² . .

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