Transparent electroconductive film

Abstract

Provided is a transparent electroconductive film that does not readily crack or turn white, even when used as one element of a layered body. [1] A transparent electroconductive film according to an embodiment of the present invention comprises a base material and an electroconductive layer that is provided on at least one side of the base material, the linear expansion coefficient of the base material being less than 6.0×10-5 / °C. [2] The electroconductive layer of the transparent electroconductive film of [1] may include metal nanowires or a metal mesh.

Description

Transparent conductive film

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

[0002] Conventionally, transparent components (e.g., transparent heating elements, transparent electrodes) composed of a transparent conductive film are known. Transparent components may be laminates containing other layers, such as glass, in addition to the transparent conductive film. For laminated transparent components, it is required that no defects such as cracks occur in the transparent conductive film during manufacturing, storage, and use.

[0003] Special Publication No. 2009-505358

[0004] The present invention was made to solve the above problems, and its main objective is to provide a transparent conductive film that is less prone to defects such as cracks, even when used as an element of a laminate.

[0005] [1] A transparent conductive film according to an embodiment of the present invention comprises a substrate and a conductive layer disposed on at least one side of the substrate, wherein the coefficient of linear expansion of the substrate is 6.0 × 10 －５ [1] The temperature is less than / °C. [2] In the transparent conductive film of [1] above, the conductive layer may contain metal nanowires or metal mesh. [3] In the transparent conductive film of [1] above, the conductive layer may contain metal nanowires, and the metal nanowires may have a fused mesh structure. [4] In the transparent conductive film of [1] above, the conductive layer may contain metal nanowires, and the content ratio of the metal nanowires in the conductive layer may be 30% to 100% by weight relative to the total weight of the conductive layer. [5] In the transparent conductive film of any of [2] to [4] above, the conductive layer may contain a polymer matrix. [6] In the transparent conductive film of any of [1] to [5] above, the in-plane phase difference Re(590) of the substrate may be 3000 nm or less. [7] In the transparent conductive film of any of [1] to [6] above, the refractive index of the substrate may be 1.45 to 1.55. [8] The transparent conductive film described in any of [1] to [7] above may be used in a transparent laminate including a glass plate.

[0006] According to embodiments of the present invention, a transparent conductive film that is less prone to cracking and whitening can be provided even when used as an element of a laminate.

[0007] This is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. This is a schematic cross-sectional view of a transparent laminate according to one embodiment of the present invention.

[0008] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0009] A. Figure 1 of the overall structure of the transparent conductive film is a schematic cross-sectional view of a transparent conductive film according to one embodiment of the present invention. The transparent conductive film 100 comprises a base material 10 and a conductive layer 20 disposed on at least one side of the base material 10.

[0010] The coefficient of linear expansion of the above substrate is 6.0 × 10⁻⁶. －５ The coefficient of linear expansion is less than / °C. By using a substrate with a specified coefficient of linear expansion in this way, it is possible to provide a transparent conductive film that is less prone to defects such as cracks, even when used as an element in a laminate. In particular, when a transparent conductive film is placed between opposing glass (film, plate), it is possible to prevent cracks from occurring in the transparent conductive film (especially cracks occurring in the substrate). This effect becomes particularly pronounced at high temperatures (for example, in an environment of 25°C to 130°C). In this specification, the coefficient of linear expansion is measured by TMA measurement in accordance with JIS K 7197.

[0011] The surface resistance of the transparent conductive film is preferably 200 Ω / □ or less, more 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 / □. The surface resistance of the transparent conductive film may also be 100 Ω / □ or less, 60 Ω / □ or less, 50 Ω / □ or less, 45 Ω / □ or less, or 40 Ω / □.

[0012] The total light transmittance of the transparent conductive film described above is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Within this range, a transparent conductive film suitable for applications such as transparent electrodes can be obtained.

[0013] The haze value of the transparent conductive film described above is preferably 20% or less, more preferably 10% or less, and even more preferably 0.1% to 5%.

[0014] The thickness of the transparent conductive film is preferably 10 μm to 500 μm, more preferably 15 μm to 300 μm, and even more preferably 20 μm to 200 μm.

[0015] In one embodiment, the transparent conductive film is used in a transparent laminate including a glass plate. Details of the transparent laminate will be described later.

[0016] B. Conductive Layer The conductive layer may have any suitable configuration as long as the effects of the present invention are obtained. Examples of conductive layers include metal oxide layers such as ITO layers, layers containing conductive fibers, and layers composed of conductive polymers.

[0017] In one embodiment, the conductive layer includes metal nanowires or a metal mesh. By forming a conductive layer including metal nanowires or a metal mesh, a transparent conductive film with excellent flexibility and light transmittance can be obtained. Furthermore, a conductive layer including metal nanowires or a metal mesh is preferable because it can be formed while preventing crack formation in the substrate. In addition, when using a substrate with high water absorption, such as a substrate made of triacetylcellulose resin described later, using metal nanowires or a metal mesh allows for the formation of a conductive layer without a vapor deposition process, resulting in a conductive layer with stable resistance. Furthermore, when using a substrate with low heat resistance, such as a substrate made of triacetylcellulose resin, using metal nanowires or a metal mesh allows for lowering the temperature during layer formation, thus preventing deterioration of the substrate.

[0018] In one embodiment, the conductive layer further comprises a polymer matrix. In this embodiment, metal nanowires or a metal mesh are present in the polymer matrix. In the conductive layer composed of the polymer matrix, the polymer matrix protects the metal nanowires or metal mesh. As a result, corrosion of the metal nanowires or metal mesh is prevented, and a transparent conductive film with superior durability can be obtained.

[0019] The thickness of the conductive layer is preferably 50 nm to 300 nm, and more preferably 80 nm to 200 nm.

[0020] The surface resistance of the conductive layer is preferably 0.01 Ω / □ to 200 Ω / □, more preferably 0.1 Ω / □ to 150 Ω / □, and particularly preferably 0.1 Ω / □ to 100 Ω / □.

[0021] In one embodiment, the conductive layer is patterned. Any suitable patterning method can be employed depending on the form 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 Publication No. 2011-511357, Japanese Unexamined Patent Publication No. 2010-164938, Japanese Unexamined Patent Publication No. 2008-310550, Japanese Patent Publication No. 2003-511799, and Japanese Patent Publication No. 2010-541109 are examples. After the conductive layer is formed on the substrate, it can be patterned using any suitable method depending on the form of the conductive layer.

[0022] The total light transmittance of the conductive layer is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more.

[0023] (Conductive layer containing metal nanowires) The above-mentioned metal nanowires refer to conductive substances made of metal, shaped like needles or threads, and having a diameter in the nanometer size range. The metal nanowires may be straight or curved. By using a conductive layer composed of metal nanowires, the metal nanowires form a mesh-like pattern, enabling the formation of a good electrical conduction path even with a small amount of metal nanowires, and obtaining a conductive optical laminate with low electrical resistance.

[0024] The ratio of the thickness d to the length L of the above-mentioned 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. By using metal nanowires with such a large aspect ratio, the metal nanowires can cross well, and high conductivity can be exhibited with a small amount of metal nanowires. As a result, a conductive layer with high light transmittance can be obtained. In this specification, the "thickness of the metal nanowire" means the diameter when the cross-section of the metal nanowire is circular, the minor axis when it is elliptical, and the longest diagonal line when it is polygonal. The thickness and length of the metal nanowires can be confirmed by a scanning electron microscope or a transmission electron microscope.

[0025] The thickness of the above-mentioned metal nanowires is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 60 nm. Within such a range, a conductive layer with high light transmittance can be formed.

[0026] The length of the above-mentioned metal nanowires is preferably 1 μm to 1000 μm, more preferably 1 μm to 500 μm, and particularly preferably 1 μm to 100 μm. Within such a range, a highly conductive conductive optical laminate can be obtained.

[0027] As the metal constituting the above metal nanowire, any appropriate metal can be used as long as it is a metal with high conductivity. Examples of the metal constituting the above metal nanowire include one or more metals selected from the group consisting of gold, platinum, silver, copper, aluminum, rhodium, and nickel. Further, a material obtained by subjecting these metals to a plating treatment (for example, gold plating treatment) may be used. The metal nanowire is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper.

[0028] As the method for manufacturing the above 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, etc. 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, Xia, Y. et al., Nano letters (2003) 3(7), 955 - 960.

[0029] In one embodiment, the metal nanowires in the above conductive layer have a fused mesh structure. The metal nanowires having a fused mesh 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 mesh structure, a transparent conductive film with higher conductivity can be obtained without impairing transparency. Further, since the content of metal nanowires can be made small while having high conductivity, by using metal nanowires having a fused mesh structure, a transparent conductive film with high conductivity and high durability (that is, small increase in resistance even under high temperature and high humidity) can be obtained.

[0030] A conductive layer containing metal nanowires having the above-described fused network structure can be formed, for example, by adding an additive to promote fusion to a metal nanowire dispersion used during conductive layer formation. Examples of such additives include metal halides (e.g., LiCl, CsCl, NaF, NaCl, NaBr, NaI, KCl, MgCl). ２ CaCl ２ AlCl ３ , AgF etc.), inorganic acids (e.g., nitric acid, nitrite, 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 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-propylpentanoic acid, pivalic acid, Examples include 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 hexadecanate, silver octadecanoate, silver pentanoate, silver pivalate, silver neoheptanoate, silver neononanoate, silver neodecanoate, etc.), and compounds containing elements that can form silver salts (chlorine, sulfur, etc.) (hydrogen chloride, sodium chloride, etc.). Preferably, these are metal halides, and more preferably, NaCl, AgF, LiF, Nabr, or NaF. In one embodiment, a conductive layer containing metal nanowires having the above-mentioned fused network structure can be formed by applying a metal nanowire dispersion containing the above-mentioned additives and then subjecting it to heat treatment and / or pressure treatment. The heat treatment temperature is, for example, between 50°C and 200°C.

[0031] A conductive layer containing metal nanowires having the above-described fused network structure may be formed by exposing a coating layer of metal nanowire dispersion to an acid halide vapor. Examples of acid halide vapors include HCl, HBr, HI, or mixtures thereof.

[0032] A metal nanowire having a fused mesh 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.

[0033] The content ratio of the metal nanowire in the conductive layer is preferably 30% by weight to 100% by weight, more preferably 30% by weight to 90% by weight, and still more preferably 45% by weight to 80% by weight with respect to the total weight of the conductive layer. Within such a range, a conductive layer excellent in conductivity and light transmittance can be obtained. Further, even when used as an element of the laminate, a transparent conductive film excellent in adhesion to an adjacent layer (for example, an adhesive layer containing a polyvinyl acetal-based adhesive) can be obtained.

[0034] The density of the metal nanowire is preferably 1.3 g / cm ３ to 10.5 g / cm ３ and more preferably 1.5 g / cm ３ to 3.0 g / cm ３ Within such a range, a conductive layer excellent in conductivity and light transmittance can be obtained.

[0035] (Conductive layer containing a metal mesh) The conductive layer containing a metal mesh is formed by arranging metal fine wires in a lattice pattern on the above-described base material. As the metal constituting the metal mesh, any appropriate metal can be used as long as it is a metal having high conductivity. Examples of the metal constituting the metal mesh include one or more metals selected from the group consisting of gold, platinum, silver, copper, aluminum, rhodium, and nickel. Further, a material obtained by subjecting these metals to a plating treatment (for example, a gold plating treatment) may be used. The metal mesh is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper.

[0036] (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, 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; and fluorine polymers. Preferably, a curable resin (preferably an ultraviolet-curable resin) composed of polyfunctional acrylates such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), and trimethylolpropane triacrylate (TMPTA) is used.

[0037] The above polymer matrix can be formed by first forming a layer of metal nanowires or metal mesh on a substrate, then applying a polymer solution onto the layer, and subsequently drying or curing the applied layer. This operation forms a conductive layer in which metal nanowires or metal mesh are present within the polymer matrix. The above polymer solution contains the polymer constituting the polymer matrix, or a precursor of the polymer (monomer constituting the polymer). The above polymer solution may contain a solvent. Examples of solvents included in the above polymer solution include alcohol-based solvents, ketone-based solvents, tetrahydrofuran, hydrocarbon-based solvents, or aromatic solvents. 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.

[0038] The coefficient of linear thermal expansion of the above polymer matrix is ​​preferably 0.5 × 10⁻⁶. －５ / ℃~8.0×10 －５ / °C, more preferably 1.0 × 10 －５ / ℃~7.0×10 －５ It is / ℃.

[0039] The refractive index of the polymer matrix is ​​preferably 1.40 to 1.70, and more preferably 1.45 to 1.55.

[0040] C. Substrate As described above, the coefficient of linear expansion of the substrate is 6.0 × 10⁻⁶ －５ It is less than / ℃. The coefficient of linear expansion of the base material is preferably 5.8 × 10 －５ / ℃ or less, more preferably 5.6 × 10 －５ The temperature is below / ℃, and more preferably 5.4 × 10 －５ It is below / °C. Within this range, the above effect becomes significant. The lower limit of the linear expansion coefficient of the substrate is, for example, 0.5 × 10 －５ It is / ℃.

[0041] The in-plane phase difference Re(590) of the above substrate is preferably 3000 nm or less, more preferably 1000 nm or less, even more preferably 500 nm or less, even more preferably 100 nm or less, and particularly preferably 10 nm or less. By using a substrate having such an in-plane phase difference, a transparent conductive film can be obtained that is less prone to visibility defects such as rainbow unevenness when light is transmitted through it. The lower limit of the in-plane phase difference Re(590) may be 5 nm, 3 nm, 2 nm, or 0 nm. The in-plane phase difference Re(λ) is the in-plane phase difference of the film measured with light of wavelength λ nm at 23°C. Therefore, Re(590) is the in-plane phase difference of the film measured with light of wavelength 590 nm. Re(λ) can be calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the film. Here, nx is the refractive index in the direction in which the refractive index is maximized (i.e., in the direction of the slow axis), and ny is the refractive index in the direction perpendicular to the slow axis in the plane.

[0042] The refractive index of the above-mentioned substrate is preferably 1.35 to 1.65, more preferably 1.40 to 1.60, even more preferably 1.45 to 1.55, and particularly preferably 1.45 to 1.50. Within this range, even when used as an element of a laminate, a transparent conductive film with suppressed reflection at the interface with adjacent layers can be obtained. It is particularly preferable in that when adjacent to an adhesive layer containing a polyvinyl acetal adhesive (preferably a polyvinyl butyral adhesive) described later, interfacial reflection with the adhesive layer is prevented. In this specification, refractive index refers to the refractive index in the planar direction.

[0043] The above-mentioned substrate is composed of any suitable resin, as long as it satisfies the above-mentioned coefficient of linear expansion. Examples of resins that constitute the above-mentioned substrate include triacetylcellulose resins and polyethylene terephthalate resins.

[0044] In one embodiment, the substrate is made of a triacetylcellulose resin. By using a triacetylcellulose resin, even when used as an element of a laminate, it is possible to obtain a transparent conductive film that is less prone to defects such as cracks and less likely to impair visibility, such as by suppressing iridescence. Furthermore, by using a triacetylcellulose resin, when used as an element of a laminate, it is possible to obtain a transparent conductive film that is less affected by components contained in adjacent adhesive layers, tack layers, etc. For example, when used in combination with a polyvinyl acetal adhesive (preferably a polyvinyl butyral adhesive), it is possible to obtain a transparent conductive film that is less affected by components contained in the adhesive (e.g., plasticizers, UV absorbers) and prevents whitening of the substrate.

[0045] The thickness of the above-mentioned substrate is preferably 8 μm to 500 μm, more preferably 10 μm to 250 μm, even more preferably 10 μm to 150 μm, and particularly preferably 15 μm to 100 μm.

[0046] The total light transmittance of the above substrate is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more.

[0047] The above-mentioned base material may further contain 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 type and amount of additives used may be appropriately determined depending on the purpose.

[0048] If necessary, various surface treatments may be performed on the above substrate. Any appropriate method can be used for the surface treatment 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 the surface of the transparent substrate hydrophilic. By making the substrate hydrophilic, the processability when coating with a conductive layer-forming composition prepared with an aqueous solvent is improved. Furthermore, a transparent conductive film with excellent adhesion between the substrate and the conductive layer can be obtained. The substrate may also be a single-layer or multi-layer structure. For example, it may be composed of a resin film and other layers formed on the resin film.

[0049] D. Method for Manufacturing a Transparent Conductive Film The transparent conductive film described above can be manufactured by any suitable method. In one embodiment, it can be formed by coating a substrate with a conductive layer-forming composition comprising metal nanowires or a metal mesh (and, optionally, a polymer matrix).

[0050] The above-mentioned conductive layer-forming composition may contain any suitable solvent. The conductive layer-forming composition may be prepared as a dispersion of metal nanowires or metal mesh. Examples of the solvent include water, alcohol-based solvents, ketone-based solvents, ether-based solvents, hydrocarbon-based solvents, and aromatic solvents. From the viewpoint of reducing environmental impact, it is preferable to use water. The above-mentioned conductive layer-forming composition may further contain any suitable additives depending on the purpose. Examples of the additives include corrosion inhibitors that prevent corrosion of metal nanowires and surfactants that prevent aggregation of metal nanowires. The type, number, and amount of additives used may be appropriately set depending on the purpose.

[0051] The dispersion concentration of metal nanowires in the above-mentioned conductive layer-forming composition is preferably 0.1% to 1% by weight. Within this range, a conductive layer with excellent conductivity and light transmittance can be formed.

[0052] Any suitable method can be used to apply the above-mentioned conductive layer-forming composition. Examples of application methods include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, intaglio printing, gravure printing, and the like. Any suitable drying method (e.g., natural drying, forced-air drying, heat drying) can be used to dry the coated layer. 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.

[0053] When a composition for forming a curable conductive layer is used, that is, when a curable resin is used as the polymer matrix, a curing treatment is performed after applying the composition for forming a curable conductive layer. The curing treatment method is chosen according to the composition of the composition for forming the curable conductive layer. For example, the curing treatment method involves heating and drying the solvent, followed by irradiation at 500 mW / cm² using an ultraviolet irradiator. ２ ~3000mW / cm ２ At this irradiation intensity, the work rate is 50 mJ / cm². ２ ~400 mJ / cm ２ One method is to irradiate it with ultraviolet light.

[0054] E. Transparent Laminate Figure 2 is a schematic cross-sectional view of a transparent laminate according to one embodiment of the present invention. The transparent laminate 200 comprises a first glass plate 110, a transparent conductive film 100, and a second glass plate 120 in this order. In one embodiment, the first glass plate 110 and the transparent conductive film 100 are laminated via an adhesive layer or a tack layer (adhesive layer 130 in the illustrated example). In one embodiment, the second glass plate 120 and the transparent conductive film 100 are laminated via an adhesive layer or a tack layer (adhesive layer 130' in the illustrated example). In one embodiment, the adhesive layer or tack layer (adhesive layer 130 in the illustrated example) is directly placed on the transparent conductive film 100. In this specification, the term "glass plate" includes the form of a glass film. The first glass plate 110 and the second glass plate 120 may have the same configuration or different configurations. Furthermore, adhesive layer 130 and adhesive layer 130' may have the same configuration or different configurations.

[0055] The thickness of the glass plates (first glass plate, second glass plate) is preferably 1.0 mm to 8.0 mm, and more preferably 3.0 mm to 6.0 mm.

[0056] The coefficient of linear expansion of the above glass plates (first glass plate, second glass plate) is preferably 0.7 × 10⁻⁶. －５ / ℃~1.0×10 －５ / ℃, more preferably 0.8 × 10 －５ ~0.9 x 10 －５ It is / ℃.

[0057] The absolute value of the difference between the linear expansion coefficient of the glass plates (first glass plate, second glass plate) and the linear expansion coefficient of the substrate is preferably 5.0 × 10⁻⁶. －５ / ℃ or less, more preferably 4.5 × 10 －５ It is below / °C. Within this range, a transparent laminate in which cracks are less likely to occur in the substrate can be obtained. The lower limit of the absolute value of the difference between the linear expansion coefficient of the glass plate (first glass plate, second glass plate) and the linear expansion coefficient of the substrate is, for example, 1.0 × 10 －５ It is / ℃.

[0058] The adhesive layer and adhesive layer described above can be any suitable adhesive or adhesive as long as the effects of the present invention are obtained. In one embodiment, the adhesive layer includes a polyvinyl acetal-based adhesive, and more preferably a polyvinyl butyral-based adhesive. These adhesives are preferred because they have excellent adhesion and do not impede the flexibility of the transparent laminate. By using the transparent conductive film of the present invention, even when a polyvinyl acetal-based adhesive is used, whitening of the substrate caused by the adhesive component can be prevented.

[0059] Adhesives or tacks may further contain any suitable additives as needed. Examples of additives include polymerization initiators, crosslinking agents, active energy ray polymerization accelerators, radical scavengers, tackifiers, plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, UV absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

[0060] The coefficient of linear expansion of the above adhesive layer is preferably 0.9 × 10⁻⁶. －５ / ℃~6.0×10 －５ / ℃, more preferably 0.85 × 10 －５ / ℃~5.0×10 －５ The temperature is / °C. The coefficient of linear expansion of the adhesive layer is preferably 0.9 × 10⁻⁶. －５ / ℃~6.0×10 －５ / ℃, more preferably 0.85 × 10 －５ / ℃~5.0×10 －５ It is / ℃.

[0061] The refractive index of the adhesive layer is preferably 1.45 to 1.55, and more preferably 1.47 to 1.50.

[0062] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. (1) Linear expansion coefficient The linear expansion coefficient of the substrate constituting the transparent conductive film was measured using a thermomechanical analyzer "TMA7000" manufactured by Hitachi High-Tech Science Corporation, based on JIS K 7197, by raising the temperature from 30°C to 150°C at a rate of 10°C / min and measuring the amount of deformation of the test film at each temperature. The linear expansion coefficient was then determined from the amount of deformation in the temperature range of 30°C to 70°C. (2) Refractive index and in-plane phase difference The refractive index and in-plane phase difference of the substrate constituting the transparent conductive film were measured using an Axometer, product name "Axoscan" manufactured by Axometrics. The measurement wavelength was 550 nm and the measurement temperature was 23°C. (3) Surface resistance The surface resistance of the transparent conductive film was measured using the eddy current method with a NAPSON product name "EC-80". The measurement temperature was 23°C. (4) Evaluation of the glass laminate A laminate consisting of a first glass plate (blue glass chemical reinforced product, 2 mm thick), a first adhesive layer (Salflex Crystal Clear 0.76 mm, manufactured by Eastman), a transparent conductive film cut to a size smaller than the glass plate, a second adhesive layer (Salflex Crystal Clear 0.76 mm, manufactured by Eastman), and a second glass plate (blue glass chemical reinforced product, 2 mm thick) was placed inside an NPC vacuum laminator (LM-50×50-S). After a 1 min degassing treatment, the heater-equipped flat plate was heated to 150°C, and then the laminate was bonded from the heated flat plate under pressure of 0.1 MPa for 5 mins. After the bonding treatment, the pressure was released for 5 mins and cooled to obtain a laminated glass (glass laminate) with the transparent conductive film bonded to it. Visual inspection of the laminated glass (glass laminate) was performed to check the visibility of the boundary of the transparent conductive film, as well as the presence or absence of whitening, film cracks, and iridescence. Furthermore, the surface resistance was measured using the method described in (3) above. The surface resistance of the glass laminate after pressure bonding was evaluated as OK if it was within twice the surface resistance of the glass laminate before pressure bonding, and NG if it was more than twice the surface resistance.

[0063] [Production Example 1] (Synthesis of silver nanowires and preparation of silver nanowire dispersion I) In a reaction vessel equipped with a stirring device, at 160°C, 5 ml of anhydrous ethylene glycol and PtCl ２ Anhydrous ethylene glycol solution (concentration: 1.5 × 10⁻⁶) －４ 0.5 ml (mol / L) was added. After 4 minutes, AgNO was added to the resulting solution. ３ 2.5 ml of an anhydrous ethylene glycol solution (concentration: 0.12 mol / l) and 5 ml of an anhydrous ethylene glycol solution of polyvinylpyrrolidone (MW: 55000) (concentration: 0.36 mol / l) were added dropwise simultaneously over 6 minutes. After this addition, the mixture was heated to 160°C and left to stand for over 1 hour to form AgNO ３ The reaction was carried out until the material 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 was increased fivefold. The reaction mixture was then centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires. The obtained silver nanowires had 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. The silver nanowires (concentration: 0.2 wt%) and pentaethylene glycol dodecyl ether (concentration: 0.1 wt%) were dispersed in pure water to prepare silver nanowire dispersion I.

[0064] [Example 1] Silver nanowire dispersion I obtained in Production Example 1 was applied to a substrate (triacetylcellulose (TAC), manufactured by Konica Minolta, product name "KC8UA", thickness 80 μm) using a die coater so that the resistance value after film formation was 100 Ω / □, and the film was formed by heating at 120°C for 2 minutes. Furthermore, a monomer composition with a solid content of 1% by weight, obtained by diluting 1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscote #300") and 0.1 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Irgacure 907") with 59 parts by weight of isopropyl alcohol and 25 parts by weight of diacetone alcohol, was applied to the silver nanowire ink coated surface using a spin coater so that the dry film thickness was 70 nm, heated at 80°C for 1 minute, and then exposed to a high-pressure mercury lamp with an integrated exposure dose of 200 mJ / cm². ２A transparent conductive film consisting of a substrate and a conductive layer was obtained by irradiating it with ultraviolet light. The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0065] [Example 2] A transparent conductive film was obtained in the same manner as in Example 1, except that a substrate (polyethylene terephthalate (PET), manufactured by Toray Industries, Inc., product name "Lumirror 125U483", thickness 125 μm) was used instead of the substrate (triacetylcellulose, manufactured by Konica Minolta, Inc., product name "KC8UA", thickness 80 μm). The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0066] [Comparative Example 1] A transparent conductive film was obtained in the same manner as in Example 1, except that a substrate (cycloolefin (COP), manufactured by Nippon Zeon Co., Ltd., product name "Zeonor Film ZF16", thickness 100 μm) was used instead of the substrate (triacetylcellulose, manufactured by Konica Minolta, product name "KC8UA", thickness 80 μm). The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0067] [Comparative Example 2] A transparent conductive film was obtained in the same manner as in Example 1, except that a substrate (polycarbonate (PC), manufactured by Teijin, product name "Panlite", thickness 100 μm) was used instead of the substrate (triacetylcellulose, manufactured by Konica Minolta, product name "KC8UA", thickness 80 μm). The obtained transparent conductive film was subjected to the above evaluation. The results are shown in Table 1.

[0068]

[0069] As is clear from Examples 1 and 2, according to the present invention, a transparent conductive film that is less prone to cracking and whitening can be obtained even when used as an element of a laminate. Furthermore, if a substrate with an in-plane phase difference of less than or equal to a predetermined value is used, a transparent conductive film that is less prone to poor visibility can be obtained (Example 1).

[0070] 10 Substrate 20 Conductive layer 100 Transparent conductive film 110 First glass plate 120 Second glass plate 130, 130' Adhesive layer 200 Transparent laminate

Claims

1. The material comprises a base material and a conductive layer disposed on at least one side of the base material, wherein the coefficient of linear expansion of the base material is 6.0 × 10 －５ A transparent conductive film with a temperature below / ℃.

2. The transparent conductive film according to claim 1, wherein the conductive layer comprises metal nanowires or a metal mesh.

3. The transparent conductive film according to claim 1, wherein the conductive layer includes metal nanowires, and the metal nanowires have a fused network structure.

4. The transparent conductive film according to claim 1, wherein the conductive layer contains metal nanowires, and the proportion of the metal nanowires in the conductive layer is 30% by weight to 100% by weight relative to the total weight of the conductive layer.

5. The transparent conductive film according to any one of claims 2 to 4, wherein the conductive layer comprises a polymer matrix.

6. The transparent conductive film according to claim 1, wherein the in-plane phase difference Re(590) of the substrate is 3000 nm or less.

7. The transparent conductive film according to claim 1, wherein the refractive index of the substrate is 1.45 to 1.

55.

8. The transparent conductive film according to claim 1, used in a transparent laminate including a glass plate.

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