Transparent conductive film

Abstract

To provide a transparent conductive film which offers superior light transmittance in the near-infrared region.SOLUTION: A transparent conductive film according to an embodiment of the present invention comprises a conductive layer, a base material, and a transmittance adjustment layer arranged in this order, where the transmittance adjustment layer has an average arithmetic average surface roughness Ra of 1.5 nm or greater, and a maximum transmittance (T1max) of the transparent conductive film in a wavelength range of 780-1600 nm and a maximum transmittance (T2max) of a laminate consisting of the conductive layer and the base material constituting the transparent conductive film in a wavelength range of 780-1600 nm satisfy the following expression: ((T1max-T2max) / T2max)×100≥3%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a transparent conductive film.

Background Art

[0002] Conventionally, as a transparent conductive film used for electrodes of touch sensors and the like, a transparent conductive film in which a metal oxide layer such as an indium-tin composite oxide layer (ITO layer) is formed on a resin film has been widely used. In recent years, the use of a transparent conductive film as a heating element has been studied. For example, it may be used for covers of cameras, sensors, etc. used for automatic driving of automobiles for the purpose of snow melting and anti-fogging. In such use, it is required to have excellent conductivity and preferably transmit the light used. Here, in the above applications, in addition to visible light, the transmittance of light in the near-infrared region may also be required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above problems, and its main object is to provide a transparent conductive film excellent in near-infrared light transmittance.

Means for Solving the Problems

[0005] [1] The transparent conductive film according to an embodiment of the present invention is a transparent conductive film including a conductive layer, a base material, and a transmittance adjustment layer in this order, wherein the arithmetic surface roughness Ra of the transmittance adjustment layer is 1.5 nm or more, and the maximum transmittance (T1max) of the transparent conductive film at a wavelength of 780 nm to 1600 nm and the maximum transmittance (T2max) of the laminate composed of the conductive layer and the base material constituting the transparent conductive film at a wavelength of 780 nm to 1600 nm satisfy the following formula: ((T1max - T2max) / T2max)×100 ≧ 3%. [2] In the transparent conductive film according to [1] above, the total light transmittance of the base material may be 85% or more. [3] In the transparent conductive film according to [1] or [2] above, the maximum height roughness Rz of the transmittance adjustment layer may be 12 nm or more. [4] In the transparent conductive film according to [1] to [3] above, the thickness of the transmittance adjustment layer may be 120 nm or more. [5] In the transparent conductive film according to [1] to [4] above, the transparent conductive film may further include a surface roughness adjustment layer between the base material and the transmittance adjustment layer, and the surface roughness adjustment layer may contain particles having a particle diameter of 0.5 μm to 3.5 μm. [Effect of the Invention]

[0006] According to an embodiment of the present invention, a transparent conductive film excellent in light transmittance in the near-infrared region can be provided. [Brief Description of the Drawings]

[0007]

Figure 1

Figure 2

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] A. Overall structure of the 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 conductive layer 10, a base material 20, and a transmittance adjustment layer 30 in this order. Although not shown, the transparent conductive film may further include any other appropriate layer. In FIG. 1, the conductive layer 10 is illustrated as having a configuration including a fibrous conductive material 11, but is not limited thereto, and the conductive layer may be, for example, a layer made of a metal film or a layer made of a metal oxide film.

[0010] In one embodiment, the transparent conductive film 100 includes a protective layer 40 disposed on the side opposite to the base material 20 of the conductive layer 10. The protective layer 40 can be a layer that protects the fibrous conductive material 11. In the embodiments of the present invention, by providing the protective layer 40, the durability of the conductive layer 10 can be improved. More specifically, a conductive layer composed of a fibrous conductive material (for example, metal nanowire) has characteristics such as low scratch resistance and humidity resistance durability. By providing a protective layer, these problems can be solved, and the durability of the conductive layer (and as a result, the durability of the transparent conductive film) can be improved. Note that the conductive layer 10 may contain a component (for example, a resin constituting the protective layer) that constitutes the protective layer 40.

[0011] FIG. 2 is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. The transparent conductive film 200 further includes a surface roughness adjustment layer 50 between a base material 20 and a transmittance adjustment layer 30. In one embodiment, the surface roughness adjustment layer 50 contains particles having a particle diameter (weight average particle diameter) of 0.5 μm to 3.5 μm. By providing a surface roughness adjustment layer containing such particles, the unevenness caused by the particles affects the surface shape of the transmittance adjustment layer, and thus the surface roughness of the transmittance adjustment layer (the surface roughness of the surface opposite to the surface roughness adjustment layer) can be adjusted. By providing a surface roughness adjustment layer, the refractive index of the transmittance adjustment layer can be preferably maintained while adjusting the surface roughness of the transmittance adjustment layer.

[0012] The maximum transmittance (T1max) of the transparent conductive film at a wavelength of 780 nm to 1600 nm and the maximum transmittance (T2max) of a laminate composed of a conductive layer and a base material constituting the transparent conductive film at a wavelength of 780 nm to 1600 nm satisfy the following formula. ((T1max - T2max) / T2max)×100 ≧ 3% Note that the “laminate composed of a conductive layer and a base material constituting the transparent conductive film” is a laminate composed of a base material and a conductive layer disposed on one surface of the base material, and can be, for example, a configuration obtained by removing the transmittance adjustment layer from the transparent conductive film. In the present specification, the value represented by ((T1max - T2max) / T2max)×100 is also referred to as the transmittance increase rate due to the transmittance adjustment layer.

[0013] In an embodiment of the present invention, a transparent conductive film having low resistance and excellent light transmittance can be provided. In one embodiment, by setting the transmittance increase rate by the transmittance adjustment layer within the above range, a transparent conductive film suitable for applications that transmit laser light in the near-infrared region can be provided. The transparent conductive film can be suitably used, for example, as a member that can efficiently transmit laser light (in the near-infrared region) required for sensing in the field of autonomous driving of vehicles using LiDAR (Light Detection And Ranging). In one embodiment, the above transparent conductive film is used for a transparent heater (for example, a transparent heater for vehicles). The transparent heater can have any suitable configuration. Typically, the transparent heater can be configured to generate heat by energizing a transparent conductive film in which a pair of electrodes are arranged. In the transparent heater, the above transparent conductive film can be used as a heat source, and it is advantageous in that it has excellent transmittance of near-infrared rays and can exhibit sufficient heat generation even at a low voltage.

[0014] "((T1max - T2max) / T2max)×100" is preferably 3.5% or more, more preferably 4% or more. Within such a range, the above effects become prominent. The upper limit of "((T1max - T2max) / T2max)×100" is, for example, 10%.

[0015] The maximum transmittance (T1max) of the transparent conductive film at a wavelength of 780 nm to 1600 nm is preferably 85% or more, more preferably 90% or more, and even more preferably 94% or more. The maximum transmittance (T1max) of the transparent conductive film at a wavelength of 780 nm to 1600 nm is preferably as high as possible, but the upper limit is, for example, 96% (preferably 98%).

[0016] The maximum transmittance (T2max) of the laminate composed of the conductive layer and the base material constituting the transparent conductive film at a wavelength of 780 nm to 1600 nm is, for example, 80% to 95%.

[0017] In one embodiment, the maximum transmittance (T3max) of the transparent conductive film at wavelengths from 380 nm to 780 nm and the maximum transmittance (T4max) of the laminate composed of the conductive layer and the substrate constituting the transparent conductive film at wavelengths from 380 nm to 780 nm satisfy the following formula. ((T3max - T4max) / T4max)×100 ≧ 2% "((T3max - T4max) / T4max)×100" is preferably 2.5% or more, more preferably 3.5% or more. The upper limit of "((T3max - T4max) / T4max)×100" is, for example, 8%.

[0018] The maximum transmittance (T3max) of the transparent conductive film at wavelengths from 380 nm to 780 nm is preferably 85% or more, more preferably 90% or more, and even more preferably 94% or more. The higher the maximum transmittance (T3max) of the transparent conductive film at wavelengths from 380 nm to 780 nm, the more preferable it is, but the upper limit is, for example, 96% (preferably 98%).

[0019] The maximum transmittance (T4max) of the laminate composed of the conductive layer and the substrate constituting the transparent conductive film at wavelengths from 380 nm to 780 nm is, for example, 80% to 95%.

[0020] The light transmittance of the above transparent conductive film at a wavelength of 905 nm is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. Within such a range, a transparent conductive film suitable for applications that transmit laser light in the near-infrared region can be provided. The higher the light transmittance at a wavelength of 905 nm, the more preferable it is, but the upper limit is, for example, 95% (preferably 98%).

[0021] The light transmittance of the above transparent conductive film at a wavelength of 555 nm is preferably 80% or more, more preferably 85% to 95%.

[0022] The arithmetic surface roughness Ra of the above transmittance adjustment layer is 1.5 nm or more. By adjusting the surface of the transmittance adjustment layer in this way, it is possible to form a transmittance adjustment layer that is excellent in slidability and not easily scratched while maintaining favorable light transmittance. For example, it is possible to prevent scratches that are likely to occur during conveyance in a roll-to-roll process. Further, when the transmittance adjustment layer and the conductive layer are in contact, such as when the transparent conductive film is in a roll shape, damage to the conductive layer can be prevented. The arithmetic surface roughness Ra can be measured in accordance with JIS B 0601.

[0023] The haze of the above transparent conductive film is preferably 0.1% to 3.0%, more preferably 0.1% to 1.5%.

[0024] The surface resistance value of the above transparent conductive film is 200 Ω / sq or less, preferably 0.01 Ω / sq to 200 Ω / sq, more preferably 1 Ω / sq to 180 Ω / sq, particularly preferably 5 Ω / sq to 150 Ω / sq, and most preferably 10 Ω / sq to 100 Ω / sq. In one embodiment, the surface resistance value of the transparent conductive film is 50 Ω / sq or less. Within such a range, a transparent conductive film particularly suitable for use as a transparent heater (especially a vehicle transparent heater) can be obtained. For example, a heater capable of generating heat at a low voltage can be realized.

[0025] The thickness of the above transparent conductive film is preferably 10 μm to 500 μm, more preferably 15 μm to 300 μm, and still more preferably 20 μm to 200 μm.

[0026] In one embodiment, the ratio of the thickness of the substrate to the thickness of the transmittance adjustment layer (substrate thickness / transmittance adjustment layer thickness) is preferably 90 to 800, more preferably 95 to 750. If it is within such a range, reflection of near-infrared rays (for example, light with a wavelength of 780 nm to 1600 nm) can be suppressed, and as a result, a transparent conductive film excellent in near-infrared transmittance can be obtained. In one embodiment, the ratio of the thickness of the substrate to the thickness of the transmittance adjustment layer (substrate thickness / transmittance adjustment layer thickness) is 100 or more (preferably 130 or more, more preferably 150 or more). If it is within such a range, a transparent conductive film with less interference unevenness can be obtained.

[0027] B. Conductive layer The conductive layer can have any suitable configuration as long as the effects of the present invention can be obtained. In one embodiment, as shown in FIG. 1, the conductive layer 10 includes a fibrous conductive material 11. By forming such a conductive layer, a transparent conductive film excellent in light transmittance, conductivity, and flexibility can be obtained. A transparent conductive film including a conductive layer containing a fibrous conductive material is also advantageous in terms of excellent heat generation characteristics, and can be preferably used, for example, as an anti-fog heater (transparent heater) in vehicle window glass. Examples of the fibrous conductive material include metal nanowires and carbon nanotubes. Preferably, metal nanowires are used. In one embodiment, the conductive layer includes a fibrous conductive material and a polymer matrix. The fibrous conductive material can be protected by the polymer matrix. As a result, corrosion of the fibrous conductive material is prevented, and a transparent conductive film with more excellent durability can be obtained.

[0028] The thickness of the conductive layer is preferably 50 nm to 300 nm, more preferably 80 nm to 200 nm.

[0029] (Fibrous conductive material) As the fibrous conductive material, metal nanowires can be preferably used.

[0030] A metal nanowire refers to a conductive material that is made of metal, has a needle-like or thread-like shape, and a diameter in the nanometer size range. The metal nanowire may be straight or curved. By using a conductive layer composed of metal nanowires, since the metal nanowires form a mesh-like pattern, even a small amount of metal nanowires can form a good electrical conduction path, and a transparent conductive film with low electrical resistance can be obtained. Furthermore, since the metal nanowires form a mesh-like pattern, openings are formed in the gaps between the meshes, and a transparent conductive film with high light transmittance can be obtained.

[0031] The ratio (aspect ratio: L / d) of the thickness d to the length L of the above fibrous conductive material (preferably, metal nanowires) is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 10,000. By using a fibrous conductive material with such a large aspect ratio, the fibrous conductive materials can cross well, and high conductivity can be exhibited by a small amount of fibrous conductive materials. As a result, a transparent conductive film with high light transmittance can be obtained. In this specification, the "thickness of the fibrous conductive material" means the diameter when the cross-section of the fibrous conductive material is circular, the minor axis when it is elliptical, and the longest diagonal line when it is polygonal. The thickness and length of the fibrous conductive material can be confirmed by a scanning electron microscope or a transmission electron microscope.

[0032] The thickness of the above fibrous conductive material (preferably, 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 50 nm. If it is in such a range, a conductive layer with high light transmittance can be formed.

[0033] The length of the above fibrous conductive material (preferably, metal nanowires) is preferably 1 μm to 1000 μm, more preferably 10 μm to 500 μm, and particularly preferably 10 μm to 100 μm. If it is in such a range, a transparent conductive film with high conductivity can be obtained.

[0034] As the metal constituting the metal nanowire, any appropriate metal can be used as long as it is a conductive metal. Examples of the metal constituting the metal nanowire include silver, gold, copper, nickel, and the like. Further, a material obtained by subjecting these metals to plating treatment (for example, gold plating treatment) may be used. Among them, preferably, from the viewpoint of conductivity, it is silver, copper, or gold, and more preferably silver.

[0035] As the method for manufacturing the metal nanowire, any appropriate method can be adopted. For example, 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, pulling out a metal nanowire at the tip of the probe, and continuously forming the metal nanowire, and the like can be mentioned. In the method of reducing silver nitrate in a 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. Uniform-sized silver nanowires 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.

[0036] The content ratio of the fibrous conductive material (preferably, metal nanowires) in the conductive layer is preferably 30% by weight to 90% by weight, and more preferably 45% by weight to 80% by weight, based on the total weight of the conductive layer. If it is within such a range, a transparent conductive film excellent in conductivity and light transmittance can be obtained.

[0037] When the metal nanowire is a silver nanowire, the density of the conductive layer is preferably 1.3 g / cm 3 ~10.5 g / cm 3 and more preferably 1.5 g / cm 3 ~3.0 g / cm 3 If it is within such a range, a transparent conductive film excellent in conductivity and light transmittance can be obtained.

[0038] In one embodiment, the conductive layer is patterned. As the patterning method, any suitable method can be adopted according to the form of the conductive layer. The shape of the pattern of the conductive layer can be any suitable shape according to 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 can be mentioned. After the conductive layer is formed on the substrate, it can be patterned by any suitable method according to the form of the conductive layer.

[0039] In one embodiment, the metal nanowires in the conductive layer have a fused network structure. The metal nanowires having a fused network structure are in a state where the metal nanowires are fused at the contact points. By forming a conductive layer containing metal nanowires having a fused network structure, a transparent conductive film with higher conductivity can be obtained without impairing transparency.

[0040] The conductive layer containing metal nanowires having the fused network structure can be formed, for example, by adding an additive for promoting fusion to the metal nanowire dispersion used when forming the conductive layer. Examples of the additive include metal halides (for example, LiCl, CsCl, NaF, NaCl, NaBr, NaI, KCl, MgCl 2 , CaCl 2 , AlCl 3, AgF, etc.), inorganic acids (e.g., nitric acid, nitrous acid, sulfuric acid, etc.), organic acids (e.g., oxalic acid, citric acid, formic acid, acetic acid, lactic acid, propionic acid, butyric acid, acrylic acid, pyruvic acid, trichloroacetic acid, trifluoroacetic acid, hexanoic acid, octanoic acid, decanoic acid, dodecanoic (lauric) acid, tetradecanoic (myristic) acid, hexadecanoic (palmitic) acid, octadecanoic (stearic) acid, 2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, 2-propylpentanoic acid, pivalic acid, neoheptanoic acid, neononanoic acid, neodecanoic acid, etc.), silver salts (e.g., silver nitrate, silver nitrite, silver lactate, silver chloride, silver sulfate, silver oxide, silver acetate, silver chlorate, silver sulfide, etc., silver formate, silver hexanoate, silver octanoate, silver decanoate, silver dodecanoate, silver tetradecanoate, silver hexadecanoate, silver octadecanoate, silver pentanoate, silver pivalate, silver neoheptanoate, silver neononanoate, silver neodecanoate, etc.), and compounds containing elements capable of forming silver salts (chlorine, sulfur, etc.) (hydrogen chloride, sodium chloride, etc.). Among them, metal halides are preferably used, and more preferably, NaCl, AgF, LiF, NaBr, or NaF. In one embodiment, the conductive layer containing the metal nanowires having the fused network structure can be formed by applying a metal nanowire dispersion containing the above additive and then performing heat treatment and / or pressure treatment. The temperature of the heat treatment is, for example, 50°C to 200°C.

[0041] The conductive layer containing the metal nanowires having the fused network structure may be formed by exposing the coating layer of the metal nanowire dispersion to acid halide vapor. Examples of the acid halide vapor include vapors such as HCl, HBr, HI, or mixtures thereof.

[0042] The metal nanowires having a fused network structure and a method for producing the same are described, for example, in Japanese Patent Application Laid-Open No. 2015-530693. The description of this publication is incorporated herein by reference.

[0043] (polymer matrix) As the polymer constituting the polymer matrix, any suitable polymer can be used. Examples of the polymer include acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, and polyamideimide; polyurethane polymers; epoxy polymers; polyolefin polymers; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone polymers; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; fluorine-based polymers, and the like. 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), trimethylolpropane triacrylate (TMPTA), etc. is used. The polymer matrix can be a resin constituting a protective layer (details will be described later).

[0044] The polymer matrix can be formed by forming a layer made of a fibrous conductive material on a substrate, then applying a polymer solution on the layer, and then drying or curing the applied layer. By this operation, a conductive layer in which the fibrous conductive material is present in the polymer matrix is formed. The polymer solution contains the polymer constituting the polymer matrix or a precursor of the polymer (a monomer constituting the polymer). The polymer solution may contain a solvent. Examples of the solvent contained in the polymer solution include alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, or aromatic solvents, etc. Preferably, the solvent is volatile. The boiling point of the solvent is preferably 200 °C or lower, more preferably 150 °C or lower, and even more preferably 100 °C or lower.

[0045] (Metal film-based conductive layer) The above conductive layer may be a layer made of a metal film or a layer made of a metal oxide film. As materials constituting such a conductive layer, for example, metals such as Cu, Al, Fe, Cr, Ti, Si, Nb, In, Zn, Sn, Au, Ag, Co, Cr, Ni, Pb, Pd, Pt, W, Zr, Ta, Hf, Mo, Mn, Mg, V, etc. are preferably used. In addition, those containing two or more of these metals, alloys, oxides, etc. having these metals as main components can also be used. For example, indium-tin composite oxide (ITO) can be used.

[0046] C. Transmittance adjustment layer The refractive index of the above transmittance adjustment layer is preferably 1.45 or less, more preferably 1.40 or less, still more preferably 1.30 or less, further preferably 1.25 or less, and particularly preferably 1.20 or less. By providing a transmittance adjustment layer having a refractive index in such a range, interface reflection of the transparent conductive film can be suppressed. As a result, a transparent conductive film excellent in light transmittance can be obtained. The lower the refractive index of the low refractive index layer, the more preferable, but the lower limit thereof is, for example, 1.07 or more (preferably 1.05 or more). The refractive index of the transmittance adjustment layer can be adjusted by the inclusion of hollow particles. In this specification, the refractive index refers to the refractive index measured at a wavelength of 550 nm.

[0047] The thickness of the transmittance adjustment layer is preferably 120 nm or more, more preferably 150 nm to 1000 nm, and still more preferably 170 nm to 600 nm. If it is in such a range, reflection of near-infrared rays (for example, light having a wavelength of 780 nm to 1600 nm) can be suppressed, and as a result, a transparent conductive film excellent in near-infrared transmittance can be obtained. In addition, a transmittance adjustment layer excellent in slidability and difficult to be scratched can be formed. In one embodiment, the thickness of the transmittance adjustment layer is less than 510 nm (preferably 500 nm or less, more preferably 400 nm or less). If it is in such a range, a transparent conductive film with less interference unevenness can be obtained.

[0048] As described above, the arithmetic surface roughness Ra of the transmittance adjustment layer is 1.5 nm or more. The arithmetic surface roughness Ra of the transmittance adjustment layer is preferably 1.5 nm or more, more preferably 2 nm or more, and even more preferably 3 nm or more. If it is within such a range, the above effects will be remarkable. The upper limit of the arithmetic surface roughness Ra of the transmittance adjustment layer can be, for example, 50 nm, 40 nm, or 30 nm. The surface shape of the transmittance adjustment layer can be adjusted, for example, by adding particles (e.g., hollow particles, solid particles, etc. described later) to the transmittance adjustment layer.

[0049] The maximum height roughness Rz of the above transmittance adjustment layer is preferably 12 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. If it is within such a range, a transmittance adjustment layer with particularly excellent slidability and less likely to be scratched can be formed. The upper limit of the maximum height roughness Rz of the transmittance adjustment layer can be, for example, 80 nm, 70 nm, or 60 nm. The maximum height roughness Rz of the transmittance adjustment layer can be measured according to JIS B 0601-2001.

[0050] In one embodiment, the transmittance adjustment layer contains any suitable resin. The transmittance adjustment layer is made to have a refractive index within the above range by any suitable method. For example, the refractive index of the transmittance adjustment layer can be adjusted by adding particles with adjustable refractive index (e.g., hollow particles, solid particles), forming voids in the resin matrix, etc. Preferably, a transmittance adjustment layer containing hollow particles is formed. By using hollow particles, a transmittance adjustment layer with a low refractive index can be preferably formed.

[0051] In one embodiment, a curable resin is used as the resin constituting the transmittance adjustment layer. By using a curable resin, a transparent conductive film with excellent scratch resistance can be obtained. Examples of the curable resin include thermosetting resins and radiation curable resins that are cured by light such as ultraviolet rays. Preferably, the above transmittance adjustment layer contains an ultraviolet curable resin. By using an ultraviolet curable resin, a transparent conductive film with excellent scratch resistance can be obtained.

[0052] As the curable resin, for example, a resin having a curable acrylate group and / or methacrylate group can be used. For example, silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, oligomers or prepolymers such as acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols can be mentioned. These may be used alone or in combination of two or more.

[0053] In one embodiment, as the curable resin, a cured product of a composition for forming a transmittance adjusting layer containing a (meth)acrylate monomer and / or a (meth)acrylate oligomer is used. Specific examples of the (meth)acrylate monomer and the (meth)acrylate oligomer include, for example, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, tris(acryloxyethyl) isocyanurate, caprolactone-modified tris(acryloxyethyl) isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, alkyl-modified dipentaerythritol tetra(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate and the like. Among them, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, or dipentaerythritol penta(meth)acrylate is preferable. The above monomers and polymers may be used alone or in combination of two or more.

[0054] In one embodiment, the composition for forming the transmittance adjustment layer contains a polyfunctional acrylate (for example, pentaerythritol triacrylate).

[0055] The composition for forming the transmittance adjustment layer contains any suitable photopolymerization initiator. Examples of the photopolymerization initiator include benzoin ethers such as benzoin normal butyl ether and benzoin isobutyl ether, benzyl ketals such as benzyldimethyl ketal and benzyldiethyl ketal, acetophenones such as 2,2-dimethoxyacetophenone and 2,2-diethoxyacetophenone, α-hydroxyalkylphenones such as 1-hydroxycyclohexyl phenyl ketone, [2-hydroxy-2-methyl-1-(4-ethylphenyl)propan-1-one], 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-2-methyl-1-(4-isopropylphenyl)propan-1-one, α-aminoalkylphenones such as 2-methyl-1-[4-(methylthio)phenyl]-1-morpholinopropane and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2,4,6-trimethylbenzoyl phenylethoxyphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0056] The composition for forming the transmittance adjustment layer may contain any suitable solvent. Examples of the solvent include MIBK (methyl isobutyl ketone), PGM (propylene glycol monomethyl ether), PMA (propylene glycol monomethyl ether acetate), TBA (tertiary butyl alcohol), and the like. A mixed solvent of these solvents may also be used.

[0057] Examples of the hollow particles include silica particles, acrylic particles, acrylic-styrene copolymer particles, and the like. Examples of the silica particles include those with the trade names "Thruia 5320" and "Thruia 4320" manufactured by JGC Catalysts and Chemicals Ltd.

[0058] The weight average particle diameter of the hollow particles may be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, and may also be 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. The weight average particle diameter can be measured by a dynamic light scattering device (DLS). The shape of the hollow particles is not particularly limited. For example, it may be in the shape of beads and substantially spherical, or may be amorphous such as powder, but a substantially spherical shape is preferred, more preferably substantially spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0059] The addition amount of the hollow particles may be, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or more, and may also be 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less with respect to 100 parts by weight of the resin. Within such a range, a transmittance adjustment layer with excellent transmittance adjustment ability and excellent transparency can be formed.

[0060] Examples of the above-mentioned solid particles include silica particles, zirconium oxide particles, titanium-containing particles (e.g., titanium oxide particles), etc. Examples of the above-mentioned silica particles include those with trade names "MEK-2140Z-AC", "MIBK-ST", "IPA-ST", etc. manufactured by Nissan Chemical Industries, Ltd. The weight-average particle diameter of the resin constituting the above-mentioned solid particles may be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, and may also be 330 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The shape of the above-mentioned solid particles is not particularly limited, and may be, for example, a bead-like substantially spherical shape, or an amorphous shape such as powder, etc., but a substantially spherical shape is preferred, more preferably, substantially spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. The addition amount of the above-mentioned solid particles may be, for example, 1 part by weight or more, 10 parts by weight or more, 20 parts by weight or more, or 30 parts by weight or more with respect to 100 parts by weight of the above-mentioned resin, and may also be 200 parts by weight or less, 150 parts by weight or less, or 100 parts by weight or less.

[0061] D. Substrate The above-mentioned base material is typically composed of any suitable resin. Examples of the resin constituting the above-mentioned base material include cycloolefin-based resins, polyimide-based resins, polyvinylidene chloride-based resins, polyvinyl chloride-based resins, polyethylene terephthalate-based resins, polyethylene naphthalate-based resins, etc. Preferably, a cycloolefin-based resin is used.

[0062] The glass transition temperature of the resin constituting the above-mentioned base material is preferably 50°C to 200°C, more preferably 60°C to 180°C, and even more preferably 70°C to 160°C.

[0063] The thickness of the above-mentioned base material 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.

[0064] The total light transmittance of the above-mentioned substrate is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Within such a range, a transparent conductive film suitable as a transparent conductive film provided in a transparent heater or the like can be obtained.

[0065] The tensile breaking strength of the above-mentioned substrate at 23°C is preferably 30 MPa to 100 MPa, more preferably 50 MPa to 95 MPa, and even more preferably 70 MPa to 90 MPa. According to the present invention, even when using a film with poor flexibility, sufficient flexibility can be exhibited as a transparent conductive film. The tensile breaking strength is measured in accordance with JIS K 7161 under normal temperature (23°C).

[0066] The above-mentioned substrate may further contain any appropriate additive as required. Specific examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. The type and amount of the additive used can be appropriately set according to the purpose.

[0067] If necessary, various surface treatments may be performed on the above-mentioned substrate. Any appropriate method is adopted for the surface treatment according to the purpose. For example, low-pressure plasma treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be mentioned. In one embodiment, the transparent substrate is surface-treated to hydrophilize the surface of the transparent substrate. If the substrate is hydrophilized, the processability is excellent when applying the composition for forming a conductive layer prepared with an aqueous solvent. In addition, a transparent conductive film excellent in the adhesion between the substrate and the conductive layer can be obtained. Further, the substrate may have a multilayer structure, for example, it may be composed of a resin film and another layer formed on the resin film.

[0068] E. Surface roughness adjustment layer As described above, the surface roughness adjustment layer contains any appropriate particles. Typically, the surface roughness adjustment layer further contains a resin.

[0069] As the resin constituting the surface roughness adjustment layer, any suitable resin can be used. As the resin, the resin described in item C above can be used.

[0070] As the particles in the surface roughness adjustment layer, for example, the above-mentioned hollow particles, solid particles, etc. can be used. Further, as the particles, organic-inorganic composite particles such as silicon-acrylic-based particles, and organic particles such as melamine-based, acrylic-based, and styrene-based particles may be used.

[0071] As described above, the weight average particle diameter of the particles contained in the surface roughness adjustment layer is 0.5 μm to 3.5 μm. The weight average particle diameter of the particles contained in the surface roughness adjustment layer is preferably 0.8 μm to 3 μm, more preferably 1 μm to 2.5 μm, and still more preferably 1.2 μm to 2 μm. If it is in such a range, the above effects will be remarkable.

[0072] The content ratio of the above particles is preferably 0.01 part by weight to 1 part by weight, more preferably 0.02 part by weight to 0.5 part by weight, and still more preferably 0.03 part by weight to 0.3 part by weight with respect to 100 parts by weight of the resin. If it is in such a range, a refractive index adjustment layer with preferably adjusted surface roughness can be formed.

[0073] The thickness of the above surface roughness adjustment layer is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5 μm, and still more preferably 0.8 μm to 3 μm. If it is in such a range, a refractive index adjustment layer with preferably adjusted surface roughness can be formed.

[0074] The ratio of the thickness of the above surface roughness adjustment layer to the weight average particle diameter of the particles (thickness of the surface roughness adjustment layer / weight average particle diameter of the particles) is preferably 1.0 to 20.0, more preferably 1.5 to 17.0. If it is in such a range, a refractive index adjustment layer with preferably adjusted surface roughness can be formed.

[0075] F. Protective layer The thickness of the above protective layer is preferably 10 nm to 1000 nm, more preferably 60 nm to 800 nm. If it is within such a range, a transparent conductive film with excellent durability can be obtained.

[0076] The total thickness of the above conductive layer and the protective layer is preferably 60 nm to 1000 nm, more preferably 70 nm to 800 nm. If it is within such a range, a transparent conductive film with excellent durability can be obtained.

[0077] Typically, the above protective layer is composed of a resin. As the resin constituting the protective layer, any appropriate resin can be used as long as the effects of the present invention can be obtained. Examples of the resin include acrylic resins; polyester resins such as polyethylene terephthalate; aromatic resins such as polystyrene, polyvinyl toluene, polyvinyl xylene, polyimide, polyamide, and polyamideimide; polyurethane resins; epoxy resins; polyolefin resins; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone resins; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubbers; fluorine-based resins, and the like.

[0078] In one embodiment, a curable resin (for example, an active energy ray curable resin, a thermosetting resin) is used as the resin for forming the above protective layer. The protective layer composed of the curable resin can be formed by curing a composition for forming a curable protective layer.

[0079] In one embodiment, a cured product of a curable protective layer-forming composition containing a (meth)acrylate monomer and / or a (meth)acrylate oligomer is used as the curable resin. By using such a resin, a protective layer with a preferably adjusted shear strength can be obtained. Specific examples of the (meth)acrylate monomer and the (meth)acrylate oligomer include, for example, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, alkyl-modified dipentaerythritol tetra(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and the like. Among them, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, or dipentaerythritol penta(meth)acrylate is preferable. The above monomers and polymers may be used alone or in combination of two or more.

[0080] In one embodiment, as the curable resin, a cured product of a composition for forming a curable protective layer containing a urethane (meth)acrylate oligomer is used. By using such a resin, a protective layer with preferably adjusted shear strength can be obtained. Examples of the urethane (meth)acrylate oligomer include an oligomer obtained by reacting a polyol and a polyisocyanate and then reacting a (meth)acrylate having a hydroxyl group, an oligomer obtained by reacting a polyisocyanate and a (meth)acrylate having a hydroxyl group and then reacting a polyol, an oligomer obtained by reacting a polyisocyanate, a polyol, and a (meth)acrylate having a hydroxyl group, and the like.

[0081] Examples of the polyol include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and their copolymers, ethylene glycol, propylene glycol, 1,4-butanediol, 2,2'-thiodiethanol, and the like.

[0082] Examples of the polyisocyanate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and the like.

[0083] Preferably, the composition for forming a curable protective layer contains any suitable photoinitiator. Examples of photoinitiators include benzoin ethers such as benzoin normal butyl ether and benzoin isobutyl ether; benzyl ketals such as benzyldimethyl ketal and benzyldiethyl ketal; acetophenones such as 2,2-dimethoxyacetophenone and 2,2-diethoxyacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl phenyl ketone, [2-hydroxy-2-methyl-1-(4-ethylphenyl)propan-1-one], 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-2-methyl-1-(4-isopropylphenyl)propan-1-one; α-aminoalkylphenones such as 2-methyl-1-[4-(methylthio)phenyl]-1-morpholinopropane and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone; monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2,4,6-trimethylbenzoyl phenylethoxyphosphine oxide; and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc.

[0084] G. Manufacturing method of the transparent conductive film The above transparent conductive film can be manufactured by any suitable method. In one embodiment, a composition for forming a transmittance adjustment layer is coated on one surface of a substrate, and a composition for forming a conductive layer is coated on the other surface of the substrate, whereby a transparent conductive film can be obtained. When the transparent conductive film includes a protective layer, after coating the composition for forming a conductive layer to form a conductive layer, a composition for forming a protective layer (polymer solution) is coated to obtain a transparent conductive film. Further, a metal nanowire may be contained in the composition for forming a protective layer, and the composition for forming a protective layer containing the metal nanowire may be coated on a substrate to obtain a transparent conductive film. Further, when the above transparent conductive film includes a surface roughness adjustment layer, a composition for forming a surface roughness adjustment layer and a composition for forming a transmittance adjustment layer are coated on one surface of the substrate in this order, and a composition for forming a conductive layer is coated on the other surface of the substrate, whereby a transparent conductive film can be obtained.

[0085] In one embodiment, the composition for forming a conductive layer includes the fibrous conductive material. The composition for forming a conductive layer may include any suitable solvent in addition to the fibrous conductive material. The composition for forming a conductive layer may be prepared as a dispersion of the fibrous conductive material. Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, aromatic solvents, etc. From the viewpoint of reducing environmental load, it is preferable to use water. The composition for forming a conductive layer may further contain any suitable additive according to the purpose. Examples of the additive include a corrosion inhibitor for preventing corrosion of the fibrous conductive material, a surfactant for preventing aggregation of the fibrous conductive material, etc. The type, number and amount of the additive used can be appropriately set according to the purpose.

[0086] The dispersion concentration of the fibrous conductive material in the composition for forming a conductive layer is preferably 0.1 wt% to 1 wt%. Within such a range, a conductive layer excellent in conductivity and light transmittance can be formed.

[0087] As a method for applying the composition for forming the conductive layer, any appropriate method can be adopted. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, relief printing method, intaglio printing method, gravure printing method, etc. As a method for drying the coating layer, any appropriate drying method (e.g., natural drying, blow drying, heat drying) can be adopted. 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.

[0088] The conductive layer (for example, a layer made of a metal film or a layer made of a metal oxide film) may be formed by any appropriate film-forming method (for example, vacuum evaporation method, sputtering method, CVD method, ion plating method, spray method, etc.). Since the film-forming method is a method known to those skilled in the art, detailed description thereof is omitted.

[0089] The composition for forming the transmittance adjustment layer uses the composition described in Item C. The solid content concentration of the composition for forming the transmittance adjustment layer is, for example, 0.1% by weight to 20% by weight, preferably 1% by weight to 10% by weight.

[0090] As described in Item E, the composition for forming the surface roughness adjustment layer contains any appropriate particles, any appropriate resin, etc. The composition for forming the surface roughness adjustment layer may contain any appropriate photopolymerization initiator (for example, the photopolymerization initiator described in Item C), solvent (for example, the solvent described in Item C), etc.

[0091] As a coating method for the composition for forming the transmittance adjustment layer and the composition for forming the surface roughness adjustment layer, any appropriate method can be adopted. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, relief printing method, intaglio printing method, gravure printing method, and the like. As a drying method for the coating layer, any appropriate drying method (e.g., natural drying, air drying, heat drying) can be adopted. 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.

[0092] When using a composition for forming a transmittance adjustment layer and / or a composition for forming a surface roughness adjustment layer containing a curable resin, after applying the composition, a curing treatment is performed. As a method for the curing treatment, any appropriate method is adopted according to the composition of the composition. As a method for the curing treatment, for example, after heat-drying the coating layer, using an ultraviolet irradiation machine, at an irradiation intensity of 500 mW / cm 2 ~3000 mW / cm 2 and irradiating ultraviolet rays with a work amount of 50 to 400 mJ / cm 2 is mentioned.

[0093] The composition for forming the protective layer contains a resin for forming the protective layer or its precursor (monomer, oligomer). The composition for forming the protective layer may further contain any appropriate additive as needed. For example, a photoinitiator, a coupling agent, etc. may be contained. Further, the composition for forming the protective layer may further contain any appropriate solvent for dilution. Examples of the solvent include toluene, butyl acetate, isobutanol, ethyl acetate, cyclohexane, cyclohexanone, methylcyclohexanone, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, diethyl ether, ethylene glycol, and the like.

[0094] As the method for applying the composition for forming the protective layer, any suitable method can be adopted. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, relief printing method, intaglio printing method, gravure printing method, and the like.

[0095] When using the composition for forming a curable protective layer, after applying the composition for forming a curable protective layer, a curing treatment is performed. As the method of the curing treatment, any suitable method is adopted according to the composition of the composition for forming a curable protective layer. Examples of the curing treatment method include, for example, after heating and drying the above solvent, using an ultraviolet irradiation machine at 500 mW / cm 2 ~3000 mW / cm 2 of irradiation intensity, and irradiating ultraviolet rays with a work amount of 50~400 mJ / cm 2 .

Examples

[0096] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods for each property are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. (1) Surface resistance The surface resistance value of the transparent conductive film (conductive layer) was measured using "EC-80" manufactured by NAPSON. The measurement temperature was 23°C. (2) Transmittance In a predetermined wavelength region, the transmittance was measured at room temperature using the transmittance measurement mode of "Hitachi Spectrophotometer U-4100" manufactured by Hitachi High-Technologies Corporation. The evaluation sample was a transparent conductive film and a laminate obtained by removing the transmittance adjustment layer from the transparent conductive film (a laminate composed of a conductive layer and a base material). From the respective transmittances, the increase rate of permeability due to the transmittance adjustment layer was calculated. Specifically, the maximum transmittance (T1max) of the transparent conductive film at wavelengths from 780 nm to 1600 nm and the maximum transmittance (T2max) of the laminate composed of the conductive layer and the substrate constituting the transparent conductive film at wavelengths from 780 nm to 1600 nm were measured, and the increase rate of permeability by the transmittance adjustment layer at wavelengths from 780 nm to 1600 nm was calculated by the calculation formula of ((T1max - T2max) / T2max)×100. (3) Arithmetic surface roughness Ra Using the AFM tapping mode of the scanning probe microscope "NanoscopeIV" manufactured by Veeco Instruments, the arithmetic surface roughness Ra in a 5 μm × 5 μm region on the surface of the transmittance adjustment layer was measured. (4) Maximum height roughness Rz Using the AFM tapping mode of the scanning probe microscope "NanoscopeIV" manufactured by Veeco Instruments, the maximum height roughness Rz in a 5 μm × 5 μm region on the surface of the transmittance adjustment layer was measured. (5) Anti-blocking property A cycloolefin polymer film (COP film, manufactured by Nippon Zeon Co., Ltd., "Zeonoa") was placed on the surface of the transmittance adjustment layer of the transparent conductive film, and a load was applied by finger pressure to evaluate the sticking condition of the film. When the COP film did not stick to the transparent conductive film at all, or when the COP film stuck slightly but immediately separated (when it fell naturally due to gravity), it was evaluated as "OK", and when the COP film stuck and did not separate, it was evaluated as "NG".

[0097] [Example 1] [1. Preparation of the composition for forming the transmittance adjustment layer] 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 120 parts by weight of hollow particles ("Through Lia 5320" manufactured by JGC Catalysts & Chemicals Ltd., weight average particle diameter: 75 nm), 10 parts by weight of a photopolymerization initiator (manufactured by BASF SE, trade name: OMNIRAD 2959), and a mixed solvent of MIBK and PGM (MIBK:PGM (weight ratio) = 1:3) were mixed to prepare a composition for forming a transmittance adjustment layer (coating liquid) having a solid content concentration of 3.5% by weight. <2. Manufacture of Substrate and Transmittance Adjustment Layer Laminate> The above composition for forming a transmittance adjustment layer was coated on a substrate (a polyethylene terephthalate film, manufactured by Mitsubishi Chemical Corporation, thickness 50 μm). For coating, a die coater was used. Using a die coater, the above composition for forming a transmittance adjustment layer (coating liquid) was coated on one side of the above PET film to form a coating film. Then, after heating at 80 °C for 1 minute, ultraviolet rays with an integrated exposure amount of 200 mJ / cm 2 were irradiated with a high-pressure mercury lamp to manufacture a laminate composed of a substrate / transmittance adjustment layer. The film thickness of the transmittance adjustment layer was 170 nm. <3. Synthesis of Silver Nanowires and Preparation of Silver Nanowire Dispersion> In a reaction vessel equipped with a stirrer, at 160 °C, 5 ml of anhydrous ethylene glycol and 0.5 ml of an anhydrous ethylene glycol solution of PtCl 2 (concentration: 1.5×10 -4 mol / L) were added. After 4 minutes had passed, to the resulting solution, 2.5 ml of an anhydrous ethylene glycol solution of AgNO 3 (concentration: 0.12 mol / l) and 5 ml of an anhydrous ethylene glycol solution of polyvinylpyrrolidone (MW: 55000) (concentration: 0.36 mol / l) were simultaneously added dropwise over 6 minutes. After this dropwise addition, it was heated to 160 °C and the reaction was carried out for 1 hour or more until AgNO 3 was completely reduced to produce 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 became 5 times, and then the reaction mixture was centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires. The obtained silver nanowires had a minor axis diameter of 30 nm to 40 nm, a major axis diameter of 30 nm to 50 nm, and a length of 5 μm to 50 μm. In pure water, the silver nanowires (concentration: 0.2% by weight) and pentaethylene glycol dodecyl ether (concentration: 0.1% by weight) were dispersed to prepare silver nanowire dispersion I. <4. Manufacture of Transparent Conductive Film> On the opposite surface of the transmittance adjustment layer of the above substrate / transmittance adjustment layer laminate, the silver nanowire dispersion I was applied using a die coater so that the resistance value after film formation would be 30 Ω / sq, and heated at 120 °C for 2 minutes to form a film. Furthermore, 1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300") and 0.1 part by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907") were diluted with 59 parts by weight of isopropyl alcohol and 25 parts by weight of diacetone alcohol to obtain a monomer composition with a solid content concentration of 1% by weight. This was applied to the silver nanowire ink-coated surface using a spin coater so that the dry film thickness would be 70 nm, heated at 80 °C for 1 minute, and then irradiated with ultraviolet rays having an integrated exposure amount of 200 mJ / cm 2 to obtain a transparent conductive film. The transparent conductive film obtained as described above was subjected to the above evaluation. The results are shown in Table 1.

[0098] [Example 2] A transparent conductive film was obtained in the same manner as in Example 1, except that the content ratio of the hollow particles in the composition for forming the transmittance adjustment layer was 150 parts by weight. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0099] [Example 3] A transparent conductive film was obtained in the same manner as in Example 1, except that the content ratio of the hollow particles in the composition for forming the transmittance adjustment layer was 80 parts by weight, and 40 parts by weight of solid particles (silica particles, "MIBK-ST" manufactured by Nissan Chemical Industries, Ltd., weight average particle diameter: 12 nm) were further added to the composition for forming the transmittance adjustment layer. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0100] [Comparative Example 1] A transparent conductive film was obtained in the same manner as in Example 1, except that the blending amount of the intermediate particles in the transmittance adjusting layer was 50 parts by weight. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0101] [Comparative Example 2] A transparent conductive film was obtained in the same manner as in Example 1, except that the blending amount of the hollow particles in the transmittance adjusting layer was 80 parts by weight. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0102] [Comparative Example 3] A transparent conductive film was obtained in the same manner as in Example 1, except that the blending amount of the hollow particles in the transmittance adjusting layer was 100 parts by weight. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0103] [Comparative Example 4] [Adjustment of the Composition for Forming the Surface Roughness Adjusting Layer] 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 20 parts by weight of silica particles (manufactured by Nissan Chemical Industries, Ltd., "MIBK-ST"), and 10 parts by weight of a photopolymerization initiator (manufactured by BASF Co., Ltd., trade name: OMNIRAD2959) were mixed. This mixture was diluted with PGM so that the solid content concentration became 16% by weight to adjust a composition (coating liquid) for forming the surface roughness adjusting layer. [Preparation of the Composition for Forming the Transmittance Adjusting Layer] 100 parts by weight of the solid content of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 80 parts by weight of hollow particles (manufactured by JGC Catalysts & Chemicals Ltd., "Thruia 5320"), 10 parts by weight of a photopolymerization initiator (manufactured by BASF Co., Ltd., trade name: OMNIRAD2959), and a mixed solvent of MIBK and PGM (MIBK:PGM (weight ratio) = 1:3) were mixed to prepare a composition (coating liquid) for forming the transmittance adjusting layer with a solid content concentration of 3.5% by weight. [Manufacture of the Substrate and the Surface Roughness Adjusting Layer] The composition for forming the surface roughness adjustment layer was applied onto a substrate (a polycarbonate film, manufactured by Keiwa Co., Ltd., thickness 100 μm). A die coater was used for the application. Then, after heating at 80°C for 1 minute, ultraviolet rays with an integrated exposure amount of 200 mJ / cm 2 were irradiated using a high-pressure mercury lamp to produce a laminate composed of the substrate / surface roughness adjustment layer. The film thickness of the surface roughness adjustment layer was 1.0 μm. <Manufacture of Substrate / Surface Roughness Adjustment Layer / Transmittance Adjustment Layer Laminate> The composition for forming the transmittance adjustment layer was applied onto the surface roughness adjustment layer of the above-mentioned substrate / surface roughness adjustment layer laminate. A die coater was used for the application. Then, after heating at 80°C for 1 minute, ultraviolet rays with an integrated exposure amount of 200 mJ / cm 2 were irradiated using a high-pressure mercury lamp to produce a laminate composed of the substrate / surface roughness adjustment layer / transmittance adjustment layer. The film thickness of the transmittance adjustment layer was 170 nm. <Synthesis of Silver Nanowires and Preparation of Silver Nanowire Dispersion> In the same manner as in Example 1, a silver nanowire dispersion I was prepared. <Manufacture of Transparent Conductive Film> The above silver nanowire dispersion I was applied onto the opposite surface of the transmittance adjustment layer of the above substrate / surface roughness adjustment layer / transmittance adjustment layer laminate using a die coater so that the resistance value after film formation would be 30 Ω / sq, and then heated at 120°C for 2 minutes to form a film. Furthermore, 1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300") and 0.1 part by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907") were diluted with 59 parts by weight of isopropyl alcohol and 25 parts by weight of diacetone alcohol to obtain a monomer composition with a solid content concentration of 1% by weight. This monomer composition was applied onto 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, ultraviolet rays with an integrated exposure amount of 200 mJ / cm 2 were irradiated using a high-pressure mercury lamp to obtain a transparent conductive film. The transparent conductive film obtained as described above was subjected to the above evaluation. The results are shown in Table 1.

[0104]

Table 1

Explanation of Symbols

[0105] 10 Conductive layer 20 Substrate 30 Transmittance adjustment layer 40 Protective layer 50 Surface roughness adjustment layer 100, 200 Transparent conductive film

Claims

1. A transparent conductive film including a conductive layer, a substrate, and a transmittance adjusting layer in this order, The transmittance adjusting layer has an arithmetic surface roughness Ra of 1.5 nm or more; a transparent conductive film, in which a maximum transmittance (T1max) of the transparent conductive film at a wavelength of 780 nm to 1600 nm and a maximum transmittance (T2max) of a laminate comprising the conductive layer and the substrate constituting the transparent conductive film at a wavelength of 780 nm to 1600 nm satisfy the following formula: ((T1max-T2max) / T2max)×100≧3%.

2. The transparent conductive film according to claim 1 , wherein the substrate has a total light transmittance of 85% or more.

3. The transparent conductive film according to claim 1 , wherein the transmittance adjusting layer has a maximum height roughness Rz of 12 nm or more.

4. The transparent conductive film according to claim 1 , wherein the transmittance adjusting layer has a thickness of 120 nm or more.

5. A surface roughness adjusting layer is further provided between the substrate and the transmittance adjusting layer, The surface roughness adjusting layer contains particles having a particle diameter of 0.5 μm to 3.5 μm. The transparent conductive film according to claim 1 .

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