Transparent conductive film

Abstract

The present application provides a transparent conductive film having excellent light transmittance in the near-infrared region. The transparent conductive film of the embodiment of the present application is a transparent conductive film provided with a conductive layer, a substrate, and a transmittance adjustment layer in this order, wherein the arithmetic mean 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 a laminate formed of 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) x 100 ≥ 3%.

Description

Technical Field

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

[0002] Traditionally, transparent conductive films used as electrodes in touch sensors have often been made by forming metal oxide layers such as indium tin oxide (ITO) layers on a resin film. In recent years, transparent conductive films have also been studied for use as heat-generating elements, for example, as protective covers for cameras and sensors used in autonomous driving systems for purposes such as snow melting and fog prevention. In these applications, excellent conductivity is required, and the light used should preferably be transmissive. Here, in addition to visible light, transmissibility in the near-infrared region is sometimes also required in these applications.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2009-505358 Summary of the Invention

[0004] The problem that the invention aims to solve The present invention was made to solve the above-mentioned problems, and its main objective is to provide a transparent conductive film with excellent near-infrared light transmittance.

[0005] Methods for solving problems [1] The transparent conductive film of the present invention is a transparent conductive film comprising a conductive layer, a substrate and a transmittance adjustment layer in sequence, wherein the arithmetic mean 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 wavelengths of 780 nm to 1600 nm and the maximum transmittance (T2max) of the laminate formed by the conductive layer and the substrate constituting the transparent conductive film at wavelengths of 780 nm to 1600 nm satisfy the following formula: ((T1max-T2max) / T2max)×100≥3%.

[0006] [2] According to the transparent conductive film described in [1] above, the total light transmittance of the substrate can be 85% or more.

[0007] [3] According to the transparent conductive film described in [1] or [2] above, the maximum height Rz of the profile of the transmittance adjustment layer can be 12 nm or more.

[0008] [4] According to the transparent conductive film described in [1] to [3] above, the thickness of the transmittance adjustment layer may be 120 nm or more.

[0009] [5] According to the transparent conductive film described in [1] to [4] above, the transparent conductive film may further have a surface roughness adjustment layer between the substrate and the transmittance adjustment layer, the surface roughness adjustment layer containing particles with a particle size of 0.5 μm to 3.5 μm.

[0010] Invention Effects According to embodiments of the present invention, a transparent conductive film with excellent transmittance to near-infrared light can be provided. Attached Figure Description

[0011] FIG. 1 This is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention.

[0012] FIG. 2 This is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. Detailed Implementation

[0013] The embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0014] A. Overall configuration of transparent conductive film FIG. 1 This is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. The transparent conductive film 100 sequentially comprises a conductive layer 10, a substrate 20, and a transmittance adjustment layer 30. Although not shown, the transparent conductive film may further include any suitable other layers. FIG. 1 The example illustrates a conductive layer 10 comprising a fibrous conductive material 11, but is not limited thereto. The conductive layer may be, for example, a layer made of a metal film or a layer made of a metal oxide film.

[0015] In one embodiment, the transparent conductive film 100 includes a protective layer 40 disposed on the side of the conductive layer 10 opposite to the substrate 20. The protective layer 40 may be a layer protecting the fibrous conductive material 11. In embodiments of the present invention, by providing the protective layer 40, the durability of the conductive layer 10 can be improved. More specifically, conductive layers composed of fibrous conductive materials (e.g., metal nanowires) have characteristics such as low scratch resistance and low humidification durability. As a result, by providing the protective layer, these problems can be eliminated, thereby improving the durability of the conductive layer (which in turn improves the durability of the transparent conductive film). Furthermore, the conductive layer 10 may also contain components constituting the protective layer 40 (e.g., a resin constituting the protective layer).

[0016] FIG. 2This 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 the substrate 20 and the transmittance adjustment layer 30. In one embodiment, the surface roughness adjustment layer 50 contains particles with a particle size (weight average particle size) of 0.5 μm to 3.5 μm. By providing a surface roughness adjustment layer containing such particles, the unevenness caused by these particles affects the surface shape of the transmittance adjustment layer, and the surface roughness of the transmittance adjustment layer (the surface roughness of the side opposite to the surface roughness adjustment layer) can be adjusted. By providing the surface roughness adjustment layer, the surface roughness of the transmittance adjustment layer can be adjusted while maintaining the refractive index of the transmittance adjustment layer well.

[0017] The maximum transmittance (T1max) of the above-mentioned transparent conductive film at wavelengths of 780nm to 1600nm and the maximum transmittance (T2max) of the laminate formed by the conductive layer constituting the transparent conductive film and the substrate at wavelengths of 780nm to 1600nm satisfy the following formula.

[0018] ((T1max-T2max) / T2max)×100≥3% Furthermore, the term "laminate formed of a conductive layer constituting a transparent conductive film and a substrate" refers to a laminate formed of a substrate and a conductive layer disposed on one side of the substrate, and for example, it can be a structure in which the transmittance adjustment layer has been removed from the transparent conductive film. In addition, in this specification, the value represented by ((T1max-T2max) / T2max)×100 is also referred to as the transmittance increase rate caused by the transmittance adjustment layer.

[0019] In embodiments of the present invention, a transparent conductive film with low resistance and excellent light transmittance can be provided. In one embodiment, by making the increase in transmittance caused by the transmittance adjustment layer within the aforementioned range, a transparent conductive film suitable for transmitting laser light in the near-infrared region can be provided. This transparent conductive film can be suitably used, for example, in the field of autonomous driving in vehicles using LiDAR (Light Detection and Ranging) to enable efficient transmission of the laser light (near-infrared region) required for sensing. In one embodiment, the aforementioned transparent conductive film is used in a transparent heater (e.g., a transparent heater for vehicles). The transparent heater can be of any suitable configuration. Typically, the transparent heater can be configured to generate heat by energizing a transparent conductive film configured with a pair of electrodes. In the transparent heater, the aforementioned transparent conductive film is advantageous in that it can be used as a heat source, has excellent near-infrared transmittance, and exhibits sufficient heating even at low voltages.

[0020] The percentage of “((T1max-T2max) / T2max)×100” is preferably 3.5% or more, more preferably 4% or more. If it is within such a range, the above effect becomes significant. The upper limit of “((T1max-T2max) / T2max)×100” is, for example, 10%.

[0021] The maximum transmittance (T1max) of the transparent conductive film in the wavelength range of 780 nm to 1600 nm is preferably 85% or more, more preferably 90% or more, and even more preferably 94% or more. A higher maximum transmittance (T1max) of the transparent conductive film in the wavelength range of 780 nm to 1600 nm is preferred, but its upper limit is, for example, 96% (preferably 98%).

[0022] The maximum transmittance (T2max) of the laminate formed by the conductive layer constituting the transparent conductive film and the substrate is, for example, 80% to 95% at wavelengths of 780 nm to 1600 nm.

[0023] In one embodiment, the maximum transmittance (T3max) of the transparent conductive film at wavelengths of 380nm to 780nm and the maximum transmittance (T4max) of the laminate formed by the conductive layer constituting the transparent conductive film and the substrate at wavelengths of 380nm to 780nm satisfy the following formula.

[0024] ((T3max-T4max) / T4max)×100≥2% The content of “((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%.

[0025] The maximum transmittance (T3max) of the transparent conductive film in the wavelength range of 380 nm to 780 nm is preferably 85% or more, more preferably 90% or more, and even more preferably 94% or more. A higher maximum transmittance (T3max) of the transparent conductive film in the wavelength range of 380 nm to 780 nm is preferred, but its upper limit is, for example, 96% (preferably 98%).

[0026] The laminate formed by the conductive layer constituting the transparent conductive film and the substrate has, for example, a maximum transmittance (T4max) of 80% to 95% at wavelengths of 380 nm to 780 nm.

[0027] The transmittance of the aforementioned 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 transmitting near-infrared laser light can be provided. Higher transmittance at a wavelength of 905 nm is more preferred, but its upper limit is, for example, 95% (preferably 98%).

[0028] The transmittance of the above-mentioned transparent conductive film at a wavelength of 555nm is preferably 80% or more, and more preferably 85% to 95%.

[0029] The arithmetic mean surface roughness Ra of the aforementioned transmittance adjustment layer is 1.5 nm or more. By adjusting the surface of the transmittance adjustment layer in this way, a transmittance adjustment layer that maintains preferred light transmittance, has excellent sliding properties, and is not prone to scratches can be formed. For example, scratches that are easily generated during roll-to-roll processing can be prevented. In addition, when the transmittance adjustment layer is in contact with the conductive layer, such as when the transparent conductive film is formed into a roll, damage to the conductive layer can be prevented. The arithmetic mean surface roughness Ra can be measured according to JIS B 0601.

[0030] The haze of the above-mentioned transparent conductive film is preferably 0.1% to 3.0%, more preferably 0.1% to 1.5%.

[0031] The surface resistivity of the aforementioned transparent conductive film is 200 Ω / □ or less, preferably 0.01 Ω / □ to 200 Ω / □, more preferably 1 Ω / □ to 180 Ω / □, particularly preferably 5 Ω / □ to 150 Ω / □, and most preferably 10 Ω / □ to 100 Ω / □. In one embodiment, the surface resistivity of the transparent conductive film is 50 Ω / □ or less. Within such a range, a transparent conductive film particularly suitable for use as a transparent heater (especially a transparent heater for vehicles) can be obtained. For example, a heater capable of heating with low voltage can be realized.

[0032] The thickness of the above-mentioned transparent conductive film is preferably 10μm to 500μm, more preferably 15μm to 300μm, and even more preferably 20μm to 200μm.

[0033] 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. Within this range, reflection of near-infrared light (e.g., light with wavelengths of 780 nm to 1600 nm) can be suppressed, resulting in a transparent conductive film with excellent near-infrared transmittance. In another embodiment, the ratio of the thickness of the substrate to the thickness of the transmittance adjustment layer (substrate thickness / transmittance adjustment layer thickness) is set to 100 or more (preferably 130 or more, more preferably 150 or more). Within this range, a transparent conductive film with minimal interference unevenness can be obtained.

[0034] B. Conductive layer The aforementioned conductive layer can be of any suitable configuration, as long as the effects of the present invention are achieved. In one embodiment, such as... FIG. 1 As shown, the conductive layer 10 includes a fibrous conductive material 11. Forming such a conductive layer yields a transparent conductive film with excellent light transmittance, conductivity, and flexibility. The transparent conductive film having a conductive layer including a fibrous conductive material also has excellent heating characteristics; for example, it is preferably used in anti-fog heaters (transparent heaters) for vehicle windows. Examples of fibrous conductive materials include metal nanowires and carbon nanotubes. Metal nanowires are preferred. 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 can be prevented, resulting in a transparent conductive film with even better durability.

[0035] The thickness of the conductive layer is preferably 50 nm to 300 nm, and more preferably 80 nm to 200 nm.

[0036] (Fiber-based conductive materials) Metal nanowires are preferably used as the aforementioned fiber-based conductive material.

[0037] Metal nanowires are conductive materials made of metal, shaped like needles or filaments, and with a diameter in the nanometer range. Metal nanowires can be straight or curved. When a conductive layer composed of metal nanowires is used, the mesh-like structure allows even a small number of nanowires to form good conductive paths, resulting in a transparent conductive film with low resistance. Furthermore, the mesh-like structure of the metal nanowires allows openings to be formed between the mesh openings, thus achieving a transparent conductive film with high light transmittance.

[0038] The ratio of the thickness d to the length L of the aforementioned fibrous conductive material (preferably 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. Using fibrous conductive materials with a large aspect ratio in this way allows for good cross-linking of the fibrous conductive materials, enabling high conductivity with a small amount of material. As a result, a transparent conductive film with high light transmittance can be obtained. Furthermore, in this specification, the term "thickness of the fibrous conductive material" refers to its diameter when the cross-section of the fibrous conductive material is circular, its minor axis when it is elliptical, and its longest diagonal when it is polygonal. The thickness and length of the fibrous conductive material can be confirmed by scanning electron microscopy or transmission electron microscopy.

[0039] The thickness of the aforementioned 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. Within such a range, a conductive layer with high light transmittance can be formed.

[0040] The length of the aforementioned fiber-based 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. Within this range, a transparent conductive film with high conductivity can be obtained.

[0041] Any suitable metal can be used as the constituent metal nanowire, as long as it is a conductive metal. Examples of metals constituting the metal nanowire include silver, gold, copper, and nickel. Alternatively, materials formed by plating these metals (e.g., gold plating) can also be used. From the viewpoint of conductivity, silver, copper, or gold are preferred, and silver is more preferred.

[0042] Any suitable method can be used as a method for manufacturing the aforementioned metal nanowires. Examples include: reducing silver nitrate in solution; applying an external voltage or current from the tip of a probe to the surface of a precursor, drawing out metal nanowires from the tip of the probe, and continuously forming the metal nanowires. In the method of reducing silver nitrate in solution, silver nanowires can be synthesized by liquid-phase reduction of silver salts such as silver nitrate in the presence of polyols such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires can be mass-produced, for example, according to the methods described in Xia, Y. et al., Chem.mater. (2002), 14, 4736-4745, and Xia, Y. et al., Nano letters (2003), 3(7), 955-960.

[0043] The percentage of the fibrous conductive material (preferably metal nanowires) in the conductive layer relative to the total weight of the conductive layer is preferably 30% to 90% by weight, more preferably 45% to 80% by weight. Within this range, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

[0044] When the aforementioned metal nanowires are silver nanowires, the density of the conductive layer is preferably 1.3 g / cm³. 3 ~10.5g / cm 3 More preferably 1.5 g / cm³ 3 ~3.0g / cm 3 If the range is as described above, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

[0045] In one embodiment, the conductive layer is patterned. As a patterning method, any suitable method can be used depending on the shape of the conductive layer. The shape of the pattern of the conductive layer can be any suitable shape depending on the application. For example, the patterns described in Japanese Patent Application Publication No. 2011-511357, Japanese Patent Application Publication No. 2010-164938, Japanese Patent Application Publication No. 2008-310550, Japanese Patent Application Publication No. 2003-511799, and Japanese Patent Application Publication No. 2010-541109 can be used. The conductive layer can be patterned using any suitable method according to the shape of the conductive layer after it has been formed on the substrate.

[0046] In one embodiment, the metal nanowires in the conductive layer have a fused mesh structure. The metal nanowires with the fused mesh structure are in a state where they are fused together at their junctions. By forming a conductive layer comprising metal nanowires with a fused mesh structure, a transparent conductive film with higher conductivity can be obtained without compromising transparency.

[0047] The aforementioned conductive layer comprising metal nanowires with a welded mesh structure can be formed, for example, by adding an additive to the metal nanowire dispersion used in forming the conductive layer to promote welding. Examples of such additives include: metal halides (e.g., LiCl, CsCl, NaF, NaCl, NaBr, NaI, KCl, MgCl2, CaCl2, AlCl3, AgF, etc.), inorganic acids (e.g., nitric acid, nitrous acid, sulfuric acid, etc.), and 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 acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (...). Stearic acid, 2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, 2-propylvaleric acid, neopentanoic 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 valerate, silver neopentanoate, silver neoheptanoate, silver neononanoate, silver neodecanoate, etc.), and compounds containing elements (chlorine, sulfur, etc.) that can form silver salts (hydrogen chloride, sodium chloride, etc.). Preferably, these are metal halides, more preferably NaCl, AgF, LiF, NaBr, or NaF. In one embodiment, the conductive layer containing the above-mentioned additives can be formed by coating a metal nanowire dispersion containing the above-mentioned additives and then subjecting it to heat treatment and / or pressure treatment. The temperature for heat treatment is, for example, 50℃ to 200℃.

[0048] The aforementioned conductive layer comprising metal nanowires with a welded mesh structure can also be formed by exposing a coating layer of a metal nanowire dispersion to an acyl halide vapor. Examples of acyl halide vapors include vapors of HCl, HBr, HI, or mixtures thereof.

[0049] Metal nanowires with a fused mesh structure and methods for manufacturing the same are described, for example, in Japanese Patent Application Publication No. 2015-530693. The description in that publication is incorporated herein by reference.

[0050] (polymer matrix) Any suitable polymer can be used as the polymer constituting the polymer matrix described above. Examples of such polymers include: acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyl toluene, polyvinyl xylene, polyimide, polyamide, and polyamide-imide; polyurethane polymers; epoxy polymers; polyolefin polymers; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone polymers; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; and fluorinated polymers. Preferably, a curable resin (preferably a UV-curable resin) made from polyfunctional acrylates such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), and trimethylolpropane triacrylate (TMPTA) is used. The polymer matrix can be a resin constituting the protective layer (details will be described below).

[0051] The polymer matrix described above can be formed by forming a layer made of a fibrous conductive material on a substrate, coating the layer with a polymer solution, and then drying or curing the coating layer. This operation forms a conductive layer containing the fibrous conductive material within the polymer matrix. The polymer solution contains a 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 solvents included in the polymer solution include: alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, or aromatic solvents. Preferably, the solvent is volatile. The boiling point of the solvent is preferably below 200°C, more preferably below 150°C, and even more preferably below 100°C.

[0052] (Metallic film conductive layer) The aforementioned conductive layer can be a layer made of a metal film or a layer made of a metal oxide film. Suitable materials for constituting such a conductive layer include 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, and V. Alternatively, alloys or oxides containing two or more of these metals, or with these metals as the main component, can also be used. For example, indium-tin oxide (ITO) can be used.

[0053] C. Transmittance adjustment layer The refractive index of the aforementioned transmittance adjustment layer is preferably 1.45 or less, more preferably 1.40 or less, even more preferably 1.30 or less, further preferably 1.25 or less, and particularly preferably 1.20 or less. By setting the transmittance adjustment layer with a refractive index in such a range as described above, interface reflection of the transparent conductive film can be suppressed. As a result, a transparent conductive film with excellent light transmittance can be obtained. The lower the refractive index of the low refractive index layer, the more preferred, but its lower limit is, for example, 1.07 or more (preferably 1.05 or more). The refractive index of the transmittance adjustment layer can be adjusted by containing hollow particles. In this specification, the refractive index refers to the refractive index measured at a wavelength of 550 nm.

[0054] The thickness of the transmittance adjustment layer is preferably 120 nm or more, more preferably 150 nm to 1000 nm, and even more preferably 170 nm to 600 nm. Within this range, reflection of near-infrared light (e.g., light with wavelengths of 780 nm to 1600 nm) can be suppressed, resulting in a transparent conductive film with excellent near-infrared transmittance. Furthermore, a transmittance adjustment layer with excellent sliding properties and resistance to scratches can be formed. In one embodiment, the thickness of the transmittance adjustment layer is set to less than 510 nm (preferably 500 nm or less, more preferably 400 nm or less). Within this range, a transparent conductive film with minimal interference unevenness can be obtained.

[0055] As described above, the arithmetic mean surface roughness Ra of the transmittance adjustment layer is 1.5 nm or more. The arithmetic mean 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 falls within such a range, the aforementioned effect becomes significant. The upper limit of the arithmetic mean 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.) to the transmittance adjustment layer.

[0056] The maximum profile height Rz of the aforementioned transmittance adjustment layer is preferably 12 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. Within such a range, a transmittance adjustment layer with particularly excellent sliding properties and resistance to scratches can be formed. The upper limit of the maximum profile height Rz of the transmittance adjustment layer can be, for example, 80 nm, 70 nm, or 60 nm. The maximum profile height Rz of the transmittance adjustment layer can be measured according to JIS B 0601-2001.

[0057] In one embodiment, the transmittance adjustment layer comprises any suitable resin. The refractive index of the transmittance adjustment layer can be set to a range described above using 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) to form voids in the resin matrix. Preferably, a transmittance adjustment layer comprising hollow particles is formed. If hollow particles are used, a transmittance adjustment layer with a low refractive index is preferably formed.

[0058] In one embodiment, a curable resin is used as the resin constituting the transmittance adjustment layer. Using a curable resin yields a transparent conductive film with excellent scratch resistance. Examples of curable resins include thermosetting resins and ionizing radiation-cured resins that are cured by light such as ultraviolet light. Preferably, the transmittance adjustment layer comprises an ultraviolet-curable resin. Using an ultraviolet-curable resin yields a transparent conductive film with excellent scratch resistance.

[0059] As the aforementioned curable resin, resins having curable acrylate groups and / or methacrylate groups can be used, for example: silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyolefin resins, oligomers or prepolymers of polyfunctional compounds such as acrylates or methacrylates of polyols, etc. One of these can be used alone, or two or more can be used in combination.

[0060] In one embodiment, the cured resin described above is a cured product of a transmissivity adjustment layer forming composition comprising (meth)acrylate monomers and / or (meth)acrylate oligomers. Specific examples of (meth)acrylate monomers and (meth)acrylate oligomers include: trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, caprolactone-modified tri(acryloyloxyethyl)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, etc. The preferred monomers are pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, or dipentaerythritol penta(meth)acrylate. One of the monomers and oligomers may be used alone, or two or more may be used in combination.

[0061] In one embodiment, the composition for forming the transmittance adjustment layer comprises a multifunctional acrylate (e.g., pentaerythritol triacrylate).

[0062] The composition for forming the transmittance adjustment layer includes any suitable photopolymerization initiator. Examples of photopolymerization initiators include: benzoin ethers such as benzoin n-butyl ether and benzoin isobutyl ether; benzyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal; acetophenones such as 2,2-dimethoxyacetophenone and 2,2-diethoxyacetophenone; 1-hydroxycyclohexylphenyl ketone, [2-hydroxy-2-methyl-1-(4-ethylhexyl)prop-1-one], 2-hydroxy-2-methyl-1-phenylprop-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-prop-1-one, 2-hydroxy-2-methyl-1-(4-isoprop-1-one] Alpha-hydroxyalkyl phenyl ketones such as 2-methyl-1-[4-(methylthio)phenyl]-1-morpholinylpropane and 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-1-butanone; monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2,4,6-trimethylbenzoyl phenyl ethoxyphosphine oxide; and monoacylphosphine oxides such as bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0063] The composition for forming the transmittance adjustment layer may contain any suitable solvent. Examples of such solvents include MIBK (methyl isobutyl ketone), PGM (propylene glycol monomethyl ether), PMA (propylene glycol monomethyl ether acetate), and TBA (tert-butanol). Mixtures of these solvents may also be used.

[0064] Examples of hollow particles mentioned above include silica particles, acrylic resin particles, and acrylic-styrene copolymer particles. Examples of silica particles include those manufactured by Nippon Ketsubai Chemical Industry Co., Ltd. under the trade names "Thrulya 5320" and "Thrulya 4320".

[0065] The weight-average particle size of the hollow particles can 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 can be less than 150 nm, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. The weight-average particle size can be measured using a dynamic light scattering (DLS) device. The shape of the hollow particles is not particularly limited; for example, they can be approximately spherical in the form of beads, or they can be amorphous such as powder. Approximately spherical particles are preferred, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0066] The amount of hollow particles added relative to 100 parts by weight of the resin can 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 can be less than 300 parts by weight, less than 270 parts by weight, less than 250 parts by weight, less than 200 parts by weight, or less than 180 parts by weight. If it is within such a range, a transmittance adjustment layer with excellent transmittance adjustment capability and excellent transparency can be formed.

[0067] Examples of solid particles include silica particles, zirconium oxide particles, and titanium-containing particles (e.g., titanium oxide particles). Examples of silica particles include those manufactured by Nissan Chemical Industries, Ltd. under the trade names "MEK-2140Z-AC," "MIBK-ST," and "IPA-ST." The weight-average particle size of the resin constituting the solid particles can 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 can 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 solid particles is not particularly limited; for example, they can be approximately spherical in the form of beads, or they can be irregular shapes such as powder. Approximately spherical particles are preferred, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles. The amount of solid particles added relative to 100 parts by weight of the resin can be, for example, 1 part or more, 10 parts or more, 20 parts or more, or 30 parts or more, and can be less than 200 parts by weight, less than 150 parts by weight, or less than 100 parts by weight.

[0068] D. Substrate The aforementioned substrate is typically composed of any suitable resin. Examples of resins constituting the substrate include cyclic olefin resins, polyimide resins, polyvinylidene chloride resins, polyvinyl chloride resins, polyethylene terephthalate resins, and polyethylene naphthalate resins. Cyclic olefin resins are preferred.

[0069] The glass transition temperature of the resin constituting the above-mentioned substrate is preferably 50°C to 200°C, more preferably 60°C to 180°C, and even more preferably 70°C to 160°C.

[0070] The thickness of the above-mentioned substrate is preferably 8μm to 500μm, more preferably 10μm to 250μm, even more preferably 10μm to 150μm, and particularly preferably 15μm to 100μm.

[0071] The total light transmittance of the aforementioned 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 for use as a transparent conductive film in transparent heaters and the like can be obtained.

[0072] 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, it can exhibit sufficient flexibility as a transparent conductive film. The tensile breaking strength is measured at room temperature (23°C) according to JIS K 7161.

[0073] The aforementioned substrate may further include any suitable additives as needed. Specific examples of additives include: plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. The types and amounts of additives used can be appropriately determined according to the purpose.

[0074] Various surface treatments can be applied to the aforementioned substrate as needed. The surface treatment employs any suitable method depending on the purpose. Examples include: low-pressure plasma treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, and acid or alkali treatment. In one embodiment, the transparent substrate is surface-treated to make its surface hydrophilic. If the substrate is made hydrophilic, the processability is excellent when coating a conductive layer forming composition prepared from an aqueous solvent. Furthermore, a transparent conductive film with excellent adhesion between the substrate and the conductive layer can be obtained. Additionally, the substrate can be multilayered, for example, it can be composed of a resin film and other layers formed on the resin film.

[0075] E. Surface roughness adjustment layer As described above, the surface roughness adjusting layer contains any suitable particles. Typically, the aforementioned surface roughness adjusting layer further contains resin.

[0076] Any suitable resin can be used as the resin constituting the surface roughness adjusting layer. The resin described in section C above can be used as this resin.

[0077] As particles in the surface roughness adjustment layer, hollow particles, solid particles, etc., as described above can be used. In addition, organic-inorganic composite particles such as silicon-acrylic acid-based particles, melamine-based particles, acrylic-based particles, and styrene-based organic particles can be used as these particles.

[0078] As described above, the weight-average particle size of the particles contained in the surface roughness adjustment layer is 0.5 μm to 3.5 μm. Preferably, the weight-average particle size of the particles contained in the surface roughness adjustment layer is 0.8 μm to 3 μm, more preferably 1 μm to 2.5 μm, and even more preferably 1.2 μm to 2 μm. When the particle size falls within such a range, the aforementioned effect becomes more pronounced.

[0079] The content ratio of the aforementioned particles is preferably 0.01 to 1 part by weight, more preferably 0.02 to 0.5 parts by weight, and even more preferably 0.03 to 0.3 parts by weight, relative to 100 parts by weight of the resin. Within such a range, a refractive index adjusting layer with preferably adjusted surface roughness can be formed.

[0080] The thickness of the aforementioned surface roughness adjustment layer is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5 μm, and even more preferably 0.8 μm to 3 μm. Within such a range, a refractive index adjustment layer with preferably adjusted surface roughness can be formed.

[0081] The ratio of the thickness of the surface roughness adjustment layer to the weight-average particle size (thickness of the surface roughness adjustment layer / weight-average particle size) is preferably 1.0 to 20.0, more preferably 1.5 to 17.0. If it is within such a range, a refractive index adjustment layer with preferably adjusted surface roughness can be formed.

[0082] F. Protective layer The thickness of the aforementioned protective layer is preferably 10 nm to 1000 nm, more preferably 60 nm to 800 nm. Within such a range, a transparent conductive film with excellent durability can be obtained.

[0083] The combined thickness of the conductive layer and the protective layer is preferably 60 nm to 1000 nm, more preferably 70 nm to 800 nm. Within this range, a transparent conductive film with excellent durability can be obtained.

[0084] Typically, the protective layer described above is composed of resin. Any suitable resin can be used as the resin constituting the protective layer, as long as the effects of the present invention are achieved. Examples of such resins include: acrylic resins; polyester resins such as polyethylene terephthalate; aromatic resins such as polystyrene, polyvinyl toluene, polyvinyl xylene, polyimide, polyamide, and polyamide-imide; polyurethane resins; epoxy resins; polyolefin resins; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone resins; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; and fluorinated resins.

[0085] In one embodiment, a curable resin (e.g., an active energy line curable resin, a thermosetting resin) is used as the resin for forming the above-mentioned protective layer. The protective layer composed of the curable resin can be formed by curing the curable protective layer forming composition.

[0086] In one embodiment, a cured composition comprising (meth)acrylate monomers and / or (meth)acrylate oligomers is used as the curable resin described above. Using such a resin yields a protective layer with preferably adjusted shear strength. Specific examples of (meth)acrylate monomers and (meth)acrylate oligomers include: trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, caprolactone-modified tri(acryloyloxyethyl)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, etc. The preferred monomers are pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, or dipentaerythritol penta(meth)acrylate. One of the monomers and oligomers may be used alone, or two or more may be used in combination.

[0087] In one embodiment, the cured product of a composition for forming a curable protective layer containing urethane (meth)acrylate oligomers is used as the aforementioned curable resin. Using such a resin yields a protective layer with preferably adjusted shear strength. Examples of urethane (meth)acrylate oligomers include: oligomers obtained by reacting a polyol with a polyisocyanate followed by reacting a hydroxyl-containing (meth)acrylate; oligomers obtained by reacting a polyisocyanate with a hydroxyl-containing (meth)acrylate followed by reacting a polyol; and oligomers obtained by reacting a polyisocyanate, a polyol, and a hydroxyl-containing (meth)acrylate.

[0088] Examples of polyols include: polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and their copolymers, ethylene glycol, propylene glycol, 1,4-butanediol, 2,2'-thiodiethanol, etc.

[0089] Examples of polyisocyanates include: isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-phenylene diisocyanate, terephthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,3-phenylenedimethyl diisocyanate, 1,4-phenylenedimethyl diisocyanate, etc.

[0090] Preferably, the above-mentioned composition for forming a curable protective layer contains any suitable photopolymerization initiator. Examples of photopolymerization initiators include: benzoin ethers such as benzoin n-butyl ether and benzoin isobutyl ether; benzyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal; acetophenones such as 2,2-dimethoxyacetophenone and 2,2-diethoxyacetophenone; 1-hydroxycyclohexylphenyl ketone, [2-hydroxy-2-methyl-1-(4-ethylhexyl)prop-1-one], 2-hydroxy-2-methyl-1-phenylprop-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-prop-1-one, 2-hydroxy-2-methyl-1-(4-isoprop-1-one) Alpha-hydroxyalkyl phenyl ketones such as 2-methyl-1-[4-(methylthio)phenyl]-1-morpholinylpropane and 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-1-butanone; monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2,4,6-trimethylbenzoyl phenyl ethoxyphosphine oxide; and monoacylphosphine oxides such as bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0091] G. Method for producing transparent conductive film The aforementioned transparent conductive film can be manufactured using any suitable method. In one embodiment, a transparent conductive film is obtained by coating a transmittance adjustment layer forming composition on one side of a substrate and a conductive layer forming composition on the other side of the substrate. When the transparent conductive film has a protective layer, a transparent conductive film is obtained by coating a conductive layer forming composition (polymer liquid) after forming the conductive layer by coating the conductive layer forming composition. Alternatively, the protective layer forming composition may contain metal nanowires, and then the protective layer forming composition containing metal nanowires may be coated onto a substrate to obtain a transparent conductive film. Furthermore, when the aforementioned transparent conductive film has a surface roughness adjustment layer, a surface roughness adjustment layer forming composition and a transmittance adjustment layer forming composition are sequentially coated on one side of the substrate, and a conductive layer forming composition is coated on the other side of the substrate to obtain a transparent conductive film.

[0092] In one embodiment, the conductive layer forming composition comprises the aforementioned fibrous conductive material. In addition to the fibrous conductive material, the conductive layer forming composition may contain any suitable solvent. The conductive layer forming composition can be prepared in the form of a dispersion of the fibrous conductive material. Examples of such solvents include water, alcohol-based solvents, ketone-based solvents, ether-based solvents, hydrocarbon-based solvents, and aromatic solvents. From the viewpoint of reducing environmental impact, water is preferred. The conductive layer forming composition may further contain any suitable additives depending on the purpose. Examples of such additives include, for instance, corrosion-resistant materials that prevent corrosion of the fibrous conductive material, and surfactants that prevent aggregation of the fibrous conductive material. The type, quantity, and amount of additives used can be appropriately determined according to the purpose.

[0093] The dispersion concentration of the fibrous conductive material in the above-mentioned conductive layer forming composition is preferably 0.1% to 1% by weight. If it is within such a range, a conductive layer with excellent conductivity and light transmittance can be formed.

[0094] As a coating method for the above-mentioned conductive layer forming composition, any suitable method can be used. Examples of coating methods include: spraying, bar coating, roller coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, gravure printing, photogravure printing, etc. As a drying method for the coating layer, any suitable drying method can be used (e.g., natural drying, air drying, heat drying). For example, in the case of heat drying, the drying temperature is typically 50°C to 200°C, preferably 80°C to 150°C. The drying time is typically 1 to 10 minutes.

[0095] The conductive layer (e.g., a layer made of a metal film or a layer made of a metal oxide film) can be formed by any suitable film-forming method (e.g., vacuum evaporation, sputtering, CVD, ion plating, spraying, etc.). This film-forming method is known to those skilled in the art, and therefore detailed descriptions are omitted.

[0096] The composition for forming the transmittance adjustment layer described above uses the composition described in section C. The concentration of the solid components in the composition for forming the transmittance adjustment layer is, for example, 0.1% to 20% by weight, preferably 1% to 10% by weight.

[0097] The surface roughness adjustment layer forming composition described above, as shown in section E, contains any suitable particles, any suitable resin, etc. The surface roughness adjustment layer forming composition may also contain any suitable photopolymerization initiator (e.g., the photopolymerization initiator described in section C), solvent (e.g., the solvent described in section C), etc.

[0098] As the coating method for the above-mentioned compositions for forming the transmittance adjustment layer and the surface roughness adjustment layer, any suitable method can be used. Examples of coating methods include: spraying, bar coating, roller coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, gravure printing, photogravure printing, etc. As the drying method for the coating layer, any suitable drying method can be used (e.g., natural drying, air drying, heat drying). For example, in the case of heat drying, the drying temperature is typically 50°C to 200°C, preferably 80°C to 150°C. The drying time is typically 1 to 10 minutes.

[0099] When using a transmittance adjustment layer forming composition and / or a surface roughness adjustment layer forming composition containing a curable resin, a curing process is performed after coating the composition. As a curing process, any suitable method can be used depending on the composition. For example, a curing process can be performed by heating and drying the coated layer, followed by irradiation with an ultraviolet light machine at 500 mW / cm². 2 ~3000mW / cm 2 The irradiation intensity and cumulative irradiation energy are 50–400 mJ / cm². 2 Ultraviolet rays.

[0100] The protective layer forming composition described above comprises a resin or its precursor (monomer, oligomer) for forming a protective layer. The protective layer forming composition may further comprise any suitable additives as needed. For example, it may contain a photopolymerization initiator, coupling agent, etc. Additionally, the protective layer forming composition may further comprise any suitable solvent for dilution. Examples of such solvents 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, etc.

[0101] As a coating method for the composition for forming the above-mentioned protective layer, any suitable method can be used. Examples of coating methods include: spraying, bar coating, roller coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, gravure printing, photogravure printing, etc.

[0102] When using a curable protective layer forming composition, a curing process is performed after coating the composition. As a method for curing, any suitable method can be used depending on the composition of the curable protective layer forming composition. For example, a curing process can be performed by heating and drying the solvent, followed by irradiation with an ultraviolet light machine at 500 mW / cm². 2 ~3000mW / cm 2The irradiation intensity and cumulative irradiation energy are 50–400 mJ / cm². 2 Ultraviolet rays.

[0103] Example The present invention will now be specifically described through examples, but the invention is not limited to these examples. The methods for measuring each characteristic are shown below. Furthermore, unless otherwise stated, "parts" and "%" in the examples and comparative examples are based on weight.

[0104] (1) Surface resistance The surface resistivity of the transparent conductive film (conductive layer) was measured using a NAPSON product, trade name "EC-80". The measurement temperature was set to 23°C.

[0105] (2) Transmittance The transmittance of a specified wavelength range was measured at room temperature using the transmittance measurement mode of the Hitachi High-Tech Science U-4100 spectrophotometer.

[0106] The evaluation samples were set as transparent conductive films and laminates obtained by removing the transmittance adjustment layer from the transparent conductive films (laminates formed by conductive layers and substrates). The increase in transmittance caused by the transmittance adjustment layer was calculated based on the transmittance of each sample.

[0107] Specifically, the maximum transmittance (T1max) of the transparent conductive film in the wavelength range of 780nm to 1600nm and the maximum transmittance (T2max) of the laminate formed by the conductive layer constituting the transparent conductive film and the substrate in the wavelength range of 780nm to 1600nm are measured. The increase rate of transmittance caused by the transmittance adjustment layer in the wavelength range of 780nm to 1600nm is calculated by the formula ((T1max-T2max) / T2max)×100.

[0108] (3) Arithmetic mean surface roughness Ra The arithmetic mean surface roughness Ra of a 5 μm × 5 μm region on the surface of the transmittance adjustment layer was measured using a scanning probe microscope “NanoscopeIV” AFM tapping mode manufactured by Veeco Instruments.

[0109] (4) Maximum profile height Rz The maximum profile height Rz of a 5μm × 5μm region on the surface of the transmittance adjustment layer was measured using a scanning probe microscope “NanoscopeIV” AFM tapping mode manufactured by Veeco Instruments.

[0110] (5) Anti-adhesion A cyclic olefin polymer film (COP film, manufactured by Zeon Corporation, Japan, "ZEONOR") was deposited on the surface of the transmittance adjustment layer of the transparent conductive film. A load was applied by finger pressure, and the film's adhesion was evaluated. Cases where the COP film was not adhered to the transparent conductive film at all, or where the COP film was slightly adhered but immediately peeled off (due to natural falling off under gravity), were evaluated as "OK". Cases where the COP film was adhered but not peeled off were evaluated as "NG".

[0111] [Example 1] <1. Preparation of a composition for forming a transmittance adjustment layer> A transmittance adjustment layer forming composition (coating liquid) with a solid content concentration of 3.5% by weight was prepared by mixing 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat#300"), 120 parts by weight of hollow particles (manufactured by Nichibukai Catalyst Chemicals, "Thrulya 5320", weight average particle size: 75nm), 10 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name: OMNIRAD2959), and a mixed solvent of MIBK and PGM (MIBK:PGM (weight ratio) = 1:3).

[0112] <2. Manufacturing of the substrate and transmittance adjustment layer laminate> The above-described transmittance adjustment layer forming composition was coated onto a substrate (polyethylene terephthalate film, manufactured by Mitsubishi Chemical Corporation, 50 μm thick). A die-coating machine was used for coating. Using the die-coating machine, the above-described transmittance adjustment layer forming composition (coating liquid) was coated onto one side of the PET film to form a coating film. Subsequently, after heating at 80°C for 1 minute, the film was irradiated with a high-pressure mercury lamp with a cumulative exposure of 200 mJ / cm². 2 The laminate, consisting of a substrate and a transmittance adjustment layer, is manufactured using ultraviolet light. Furthermore, the transmittance adjustment layer has a thickness of 170 nm.

[0113] <3. Synthesis of silver nanowires and preparation of silver nanowire dispersions> In a reaction vessel equipped with a stirrer, add 5 ml of anhydrous ethylene glycol and an anhydrous ethylene glycol solution of PtCl2 (concentration: 1.5 × 10⁻⁶) at 160°C. -40.5 ml of anhydrous ethylene glycol solution of AgNO3 (concentration: 0.12 mol / L) and 5 ml of anhydrous ethylene glycol solution of polyvinylpyrrolidone (MW: 55000) (concentration: 0.36 mol / L) were simultaneously added dropwise to the obtained solution over a period of 6 minutes. After this addition, the mixture was heated to 160 °C and reacted for more than 1 hour until AgNO3 was completely reduced to form silver nanowires. Subsequently, acetone was added to the reaction mixture containing silver nanowires obtained in the above manner until the volume of the reaction mixture was 5 times that of the original volume. The reaction mixture was then centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires.

[0114] The obtained silver nanowires have a short diameter of 30 nm to 40 nm, a long diameter of 30 nm to 50 nm, and a length of 5 μm to 50 μm.

[0115] Silver nanowire dispersion I was prepared by dispersing the silver nanowires (concentration: 0.2 wt%) and pentaethylene glycol dodecyl ether (concentration: 0.1 wt%) in pure water.

[0116] <4. Fabrication of Transparent Conductive Films> Using a die coater, the above-mentioned silver nanowire dispersion I was coated onto the opposite surface of the transmittance adjustment layer of the above-mentioned substrate / transmittance adjustment layer laminate in such a way that the resistivity value after film formation is 30Ω / □, and the film was formed by heating at 120°C for 2 minutes.

[0117] Subsequently, 1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300") and 0.1 part by weight of photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907") were diluted with 59 parts by weight of isopropanol and 25 parts by weight of diacetone alcohol. The resulting monomer composition with a solid content of 1% by weight was coated onto the above-mentioned silver nanowire ink coating surface using a spin coater to achieve a dry film thickness of 70 nm. After heating at 80°C for 1 minute, the mixture was irradiated with a high-pressure mercury lamp with a cumulative exposure of 200 mJ / cm. 2 Ultraviolet light is used to obtain a transparent conductive film.

[0118] The transparent conductive film obtained in the manner described above was used for the above evaluation. The results are shown in Table 1.

[0119] [Example 2] The hollow particle content in the composition for forming the transmittance adjustment layer was set to 150 parts by weight, and otherwise, a transparent conductive film was obtained in the same manner as in Example 1. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0120] [Example 3] The hollow particle content in the composition for forming the transmittance adjustment layer was set to 80 parts by weight, and 40 parts by weight of solid particles (silica particles, manufactured by Nissan Chemical Co., Ltd., "MIBK-ST", weight average particle size: 12 nm) were further added to the composition for forming the transmittance adjustment layer. Otherwise, a transparent conductive film was obtained in the same manner as in Example 1. The obtained transparent conductive film was evaluated as described above. The results are shown in Table 1.

[0121] [Comparative Example 1] The amount of hollow particles in the transmittance adjustment layer was set to 50 parts by weight, and otherwise, a transparent conductive film was obtained in the same manner as in Example 1. The obtained transparent conductive film was then evaluated as described above. The results are shown in Table 1.

[0122] [Comparative Example 2] The amount of hollow particles in the transmittance adjustment layer was set to 80 parts by weight, and otherwise, a transparent conductive film was obtained in the same manner as in Example 1. The obtained transparent conductive film was then evaluated as described above. The results are shown in Table 1.

[0123] [Comparative Example 3] The amount of hollow particles in the transmittance adjustment layer was set to 100 parts by weight, and otherwise, a transparent conductive film was obtained in the same manner as in Example 1. The obtained transparent conductive film was used for the above evaluation. The results are shown in Table 1.

[0124] [Comparative Example 4] <Adjustment of the composition for forming the surface roughness adjustment layer> 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300"), 20 parts by weight of silica particles (manufactured by Nissan Chemical, Ltd., "MIBK-ST"), and 10 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name: OMNIRAD2959) were mixed. The mixture was diluted with PGM to achieve a solids concentration of 16% by weight to form a surface roughness adjustment layer composition (coating liquid).

[0125] <Preparation of the composition for forming the transmittance adjustment layer> A transmittance adjustment layer forming composition (coating liquid) with a solid content concentration of 3.5% by weight is prepared by mixing 100 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat#300"), 80 parts by weight of hollow particles (manufactured by Nichibukai Catalyst Chemicals Co., Ltd., trade name: OMNIRAD2959), 10 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name: OMNIRAD2959), and a mixed solvent of MIBK and PGM (MIBK:PGM (weight ratio) = 1:3).

[0126] <Manufacturing of substrate and surface roughness adjustment layer> The above-mentioned composition for forming the surface roughness adjustment layer was applied to a substrate (polycarbonate film, manufactured by Huihe Company, 100 μm thick). A die-coating machine was used for application. Subsequently, after heating at 80°C for 1 minute, the substrate was irradiated with a high-pressure mercury lamp with a cumulative exposure of 200 mJ / cm². 2 The ultraviolet light is used to create a laminate consisting of a substrate / surface roughness adjustment layer. Furthermore, the surface roughness adjustment layer has a film thickness of 1.0 μm.

[0127] <Manufacturing of the substrate / surface roughness adjustment layer / transmittance adjustment layer laminate> The above-described transmittance adjustment layer forming composition was applied to the surface roughness adjustment layer of the above-described substrate / surface roughness adjustment layer laminate. A die-coating machine was used for application. Subsequently, after heating at 80°C for 1 minute, the substrate was irradiated with a high-pressure mercury lamp with a cumulative exposure of 200 mJ / cm². 2 The ultraviolet light is used to create a laminate consisting of a substrate / surface roughness adjustment layer / transmittance adjustment layer. Furthermore, the transmittance adjustment layer has a thickness of 170 nm.

[0128] <Synthesis of Silver Nanowires and Preparation of Silver Nanowire Dispersions> Silver nanowire dispersion I was prepared in the same manner as in Example 1.

[0129] <Manufacturing of Transparent Conductive Films> Using a die coater, the above-mentioned silver nanowire dispersion I was coated onto the opposite surface of the transmittance adjustment layer of the above-mentioned substrate / surface roughness adjustment layer / transmittance adjustment layer laminate in such a way that the resistance value after film formation is 30Ω / □, and the film was formed by heating at 120°C for 2 minutes.

[0130] Subsequently, 1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300") and 0.1 part by weight of photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907") were diluted with 59 parts by weight of isopropanol and 25 parts by weight of diacetone alcohol. The resulting monomer composition with a solid content of 1% by weight was coated onto the above-mentioned silver nanowire ink coating surface using a spin coater to achieve a dry film thickness of 70 nm. After heating at 80°C for 1 minute, the mixture was irradiated with a high-pressure mercury lamp with a cumulative exposure of 200 mJ / cm. 2 Ultraviolet light is used to obtain a transparent conductive film.

[0131] The transparent conductive film obtained in the manner described above was used for the above evaluation. The results are shown in Table 1.

[0132] [Table 1]

[0133] Symbol Explanation 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, comprising a conductive layer, a substrate, and a transmittance adjustment layer sequentially, wherein, The arithmetic mean surface roughness Ra of the transmittance adjustment layer is greater than 1.5 nm. The maximum transmittance T1max of the transparent conductive film in the wavelength range of 780nm to 1600nm and the maximum transmittance T2max of the laminate formed by the conductive layer constituting the transparent conductive film and the substrate in the wavelength range of 780nm to 1600nm satisfy the following formula. ((T1max-T2max) / T2max)×100≥3%.

2. The transparent conductive film according to claim 1, wherein, The total light transmittance of the substrate is above 85%.

3. The transparent conductive film according to claim 1, wherein, The maximum height Rz of the transmittance adjustment layer is above 12 nm.

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

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

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