JP6745177B2 - Light-transmissive conductive film - Google Patents

Description

The present invention relates to a light-transmitting conductive film having light-transmitting property and conductivity.

In recent years, touch panel type liquid crystal display devices have been widely used in electronic devices such as smartphones, mobile phones, notebook computers, tablet PCs, copiers and car navigation systems. In such a liquid crystal display device, a light-transmitting conductive film in which a transparent conductive layer is laminated on a base material is used.

In Patent Document 1 below, a transparent conductive film in which a transparent film substrate, a transparent SiO _x (x=1.0 to 2.0) thin film, and a transparent conductive thin film are laminated in this order. Is disclosed. The transparent SiO _x thin film has a thickness of 10 to 100 nm, a light refractive index of 1.40 to 1.80, and an average surface roughness [Ra] of 0.8 to 3.0 nm. Have. The transparent conductive thin film has a thickness of 20 to 35 nm, a SnO ₂ /(In ₂ O ₃ +SnO ₂ ) weight ratio of _{3 to} 15% by weight, and is formed of an indium-tin composite oxide. ing.

Patent Document 2 below discloses a transparent conductive film in which a base film, a high refractive index layer, a SiO ₂ film, and a transparent conductive film are laminated in this order. The high refractive index layer has a refractive index of 1.61 to 1.80 and a thickness of 30 nm or more. The SiO ₂ film preferably has a refractive index of 1.40 to 1.50, and preferably has a thickness of 3 to 30 nm.

JP 2006-19239 A WO2013/038718A1

For example, in a touch panel, it is necessary to increase the conductivity of the transparent conductive layer in order to improve operability and increase the size while maintaining high-definition display. In order to reduce the resistance value of the transparent conductive layer, it is necessary to make the transparent conductive layer thick. However, if the transparent conductive layer is made thick, the visibility tends to decrease. Further, in the conventional transparent conductive film, the conductivity tends to decrease when exposed to high temperature or high humidity.

An object of the present invention is to provide a light-transmissive conductive film that can improve visibility and reduce resistance even if the conductive layer has a thickness of 21 nm or more.

According to a broad aspect of the present invention, a conductive layer having optical transparency and conductivity, a low refractive index layer and a high refractive index layer disposed on one surface side of the conductive layer, the conductive layer Is 21 nm or more and 35 nm or less, the thickness of the low refractive index layer is 21 nm or more and 30 nm or less, the thickness of the high refractive index layer is 0.4 μm or more and 2 μm or less, and the low There is provided a light-transmissive conductive film, wherein the refractive index of the refractive index layer is 1.40 or more and 1.55 or less, and the refractive index of the high refractive index layer is 1.65 or more.

In a specific aspect of the light-transmitting conductive film according to the present invention, the surface resistance of the conductive layer is 110Ω/□ or less, and the total light transmittance is 89% or more.

In a specific aspect of the light transmissive conductive film according to the present invention, the transmission color difference is 1.9 or less and the reflection color difference is 6.0 or less.

The light-transmitting conductive film according to the present invention includes a conductive layer having light-transmitting property and conductivity, and a low refractive index layer and a high refractive index layer arranged on one surface side of the conductive layer, The conductive layer has a thickness of 21 nm or more and 35 nm or less, the low refractive index layer has a thickness of 21 nm or more and 30 nm or less, and the high refractive index layer has a thickness of 0.4 μm or more and 2 μm or less, Since the refractive index of the low refractive index layer is 1.40 or more and 1.55 or less and the refractive index of the high refractive index layer is 1.65 or more, the thickness of the conductive layer is 21 nm or more. Nevertheless, the visibility can be increased and the resistance value can be reduced.

FIG. 1 is a sectional view showing a light-transmissive conductive film according to the first embodiment of the present invention. FIG. 2 is a sectional view showing a light-transmissive conductive film according to the second embodiment of the present invention.

Hereinafter, the details of the present invention will be described.

The light-transmitting conductive film according to the present invention includes a conductive layer, a low refractive index layer, and a high refractive index layer. The low refractive index layer and the high refractive index layer are arranged on one surface side of the conductive layer. Both of the low refractive index layer and the high refractive index layer are arranged on one surface side of both surfaces of the conductive layer. The low refractive index layer has a lower refractive index than the high refractive index layer. The high refractive index layer has a higher refractive index than the low refractive index layer. In the present specification, the high refractive index layer and the low refractive index layer may be collectively referred to as a refractive index adjusting layer.

Since the present invention is provided with the above configuration, it is possible to reduce the color difference, enhance the visibility, and reduce the resistance value, even though the conductive layer has a thickness of 21 nm or more.

Further, in the present invention, since the above configuration is provided, it is possible to suppress the decrease in conductivity when exposed to high temperature or high humidity. That is, in the present invention, resistance to moist heat can be improved.

From the viewpoint of effectively lowering the resistance value, the thickness of the conductive layer is preferably 25 nm or more, more preferably 30 nm or more. In the present invention, when the conductive layer is thick, the effects of the present invention are more effectively exhibited.

From the viewpoint of effectively reducing the color difference and effectively lowering the resistance value, the ratio of the thickness of the high refractive index layer to the thickness of the low refractive index layer (thickness of high refractive index layer/low refractive index) The thickness of the rate layer is preferably 22 or more, more preferably 50 or more, preferably 95 or less, more preferably 71 or less.

From the viewpoint of effectively reducing the color difference and effectively lowering the resistance value, the ratio of the refractive index of the high refractive index layer to the refractive index of the low refractive index layer (refractive index of high refractive index layer/low refractive index) The refractive index of the refractive index layer) is preferably 1.05 or more, more preferably 1.1 or more, preferably 1.4 or less, more preferably 1.3 or less.

Since the pattern of the conductive layer is hardly visible in the light-transmitting conductive film according to the present invention, the visibility of display light can be enhanced when used in a liquid crystal display device. Therefore, the light transmissive conductive film can be suitably used for a liquid crystal display device.

Particularly, in the touch panel, when the pattern of the conductive layer is visually recognized, the display quality and usability are greatly adversely affected. Since the pattern of the conductive layer is hard to be visually recognized, the light-transmissive conductive film according to the present invention can be preferably used for a liquid crystal display device and can be more preferably used for a touch panel.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the following drawings, the thickness of each layer is different from the actual thickness for convenience of illustration.

FIG. 1 is a sectional view showing a light-transmissive conductive film according to the first embodiment of the present invention.

As shown in FIG. 1, the light-transmitting conductive film 1 includes a base material 2, a conductive layer 3, a low refractive index layer 4, a high refractive index layer 5 and a protective film 6.

The base material 2 has a first surface 2a and a second surface 2b. The first surface 2a and the second surface 2b face each other. A refractive index adjusting layer including a low refractive index layer 4 and a high refractive index layer 5 is laminated on the first surface 2a of the base material 2. In the present embodiment, the high refractive index layer 5 is laminated on the first surface 2a of the base material 2. The low refractive index layer 4 is laminated on the surface of the high refractive index layer 5 opposite to the base material 2 side. The conductive layer 3 is laminated on the surface of the low refractive index layer 4 opposite to the high refractive index layer 5 side. The low refractive index layer 4 is in contact with the conductive layer 3. The first surface 2a of the base material 2 is the surface on which the refractive index adjusting layer is laminated. The base material 2 is a member arranged between the refractive index adjusting layer and the protective film 6, and is a member arranged between the conductive layer 3 and the protective film 6, and the conductive layer 3 and the refractive index adjusting layer. It is a support member of.

A low refractive index layer is preferably laminated on the surface of the conductive layer, and a high refractive index layer is preferably laminated on the surface side of the low refractive index layer opposite to the conductive layer side. The low refractive index layer may be laminated on the surface of the conductive layer, and the high refractive index layer may be laminated on the surface side of the low refractive index layer opposite to the conductive layer side.

The protective film 6 is laminated on the second surface 2b of the base material 2. The second surface 2b is the surface on the side where the protective film 6 is laminated. By providing the protective film 6, the second surface 2b of the base material 2 can be protected.

The substrate 2 has a substrate film 11 and first and second hard coat layers 12 and 13. The base film 11 is made of a material having high light transmittance. The second hard coat layer 13 is laminated on the surface of the base film 11 on the conductive layer 3 side.

The first hard coat layer 12 is laminated on the surface of the base film 11 on the protective film 6 side. The first hard coat layer 12 is in contact with the protective film 6.

The conductive layer 3 is made of a material having high light transmittance and high conductivity. The conductive layer 3 is partially laminated on the surface of the refractive index adjusting layer. The light-transmitting conductive film 1 has a portion where the conductive layer 3 is present and a portion where the conductive layer 3 is not present on the surface of the refractive index adjusting layer.

The protective film may be laminated on the second surface of the base material with an adhesive layer. The second surface of the base material is preferably in contact with the pressure-sensitive adhesive layer of the protective film.

FIG. 2 is a sectional view showing a light-transmissive conductive film according to the second embodiment of the present invention.

As shown in FIG. 2, in the light-transmitting conductive film 1A, the first hard coat layer 12 is not provided. The light-transmitting conductive film 1A has a base material 2A in which a second hard coat layer 13 and a base film 11 are laminated in this order. In the light-transmitting conductive film 1A, the protective film 6 is laminated directly on the surface of the base film 11 opposite to the conductive layer 3.

In the light transmissive conductive film according to the present invention, unlike the light transmissive conductive film 1A, the first hard coat layer may not be provided. The protective film may be directly laminated on the surface of the base film. Further, the second hard coat layer may not be provided. A refractive index adjusting layer and a conductive layer may be laminated in this order on the surface of the base film on the conductive layer side.

Next, a method for manufacturing the light-transmitting conductive film 1 shown in FIG. 1 will be described.

The light-transmissive conductive film 1 can be produced, for example, by the following method.

The first hard coat layer 12 is formed on one surface of the base film 11. Specifically, when an ultraviolet curable resin is used as the resin, first, the photocurable monomer and the photoinitiator are stirred in a diluent to prepare a coating liquid. The obtained coating liquid is applied onto the base film 11, and the resin is cured by irradiating with ultraviolet rays to form the first hard coat layer 12.

Then, the protective film 6 is formed on the first hard coat layer 12. When a protective film having a pressure-sensitive adhesive layer provided on a base material sheet is used as the protective film 6, an adhesive surface is attached to the surface of the first hard coat layer 12 to form a layer on the first hard coat layer 12. The protective film 6 can be formed.

Next, the second hard coat layer 13 is formed on the surface of the base film 11 opposite to the first hard coat layer 12. Specifically, when an ultraviolet curable resin is used as the resin, first, the photocurable monomer and the photoinitiator are stirred in a diluent to prepare a coating liquid. The obtained coating liquid is applied on the surface of the base film 11 opposite to the first hard coat layer 12 side, and the resin is cured by irradiation with ultraviolet rays to form the second hard coat layer 13. ..

Next, the high refractive index layer 5 and the low refractive index layer 4 are formed on the second hard coat layer 13. Specifically, when SiO ₂ is used, the refractive index adjusting layer can be formed on the second hard coat layer 13 by vapor deposition or sputtering.

As described above, the first and second hard coat layers 12 and 13, the high refractive index layer 5 and the low refractive index layer 4 are formed on the base film 11. In addition, in the present invention, the first and second hard coat layers 12 and 13 may not be provided. In this case, the surface of the base material film 11 on the conductive layer 3 side is the first surface 2a of the base material 2, and the surface of the base material film 11 on the protective film 6 side is the second surface of the base material 2. It is the surface 2b. Further, when the high refractive index layer 5 is formed as a hard coat layer, the second hard coat layer 13 may be omitted.

Next, the light-transmitting conductive film 1 can be produced by forming the conductive layer 3 on the refractive index adjusting layer (the high refractive index layer 5 and the low refractive index layer 4).

The method for forming the conductive layer is not particularly limited. For example, a method of etching a metal film formed by vapor deposition or sputtering, various printing methods such as screen printing or inkjet printing, and a known patterning method such as a photolithography method using a resist can be used. The formed conductive layer 3 preferably has an increased crystallinity by an annealing process.

Hereinafter, details of each layer constituting the light-transmitting conductive film will be described.

(Base material)
The total thickness of the substrate is not particularly limited, but is preferably 23 μm or more, more preferably 50 μm or more, preferably 300 μm or less, more preferably 200 μm or less.

Base film;
The base film preferably has high light transmittance. Therefore, the material of the substrate film is not particularly limited, but for example, polyolefin, polyether sulfone, polysulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene na. Examples thereof include phthalate, triacetyl cellulose, and cellulose nanofiber. The cycloolefin polymer may be a cycloolefin copolymer. The material of the base film may be used alone or in combination of two or more.

The thickness of the substrate film is preferably 5 μm or more, more preferably 20 μm or more, preferably 190 μm or less, more preferably 125 μm or less. When the thickness of the base film is not less than the above lower limit and not more than the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized.

Regarding the light transmittance of the substrate film, the average transmittance in the visible light region of wavelength 380 to 780 nm is preferably 85% or more, more preferably 90% or more.

Further, the base film may contain various stabilizers, ultraviolet absorbers, plasticizers, lubricants or colorants.

First and second hard coat layers;
Each of the first and second hard coat layers is preferably composed of a binder resin. The binder resin is preferably a cured resin. As the curable resin, a thermosetting resin, an active energy ray curable resin, or the like can be used. From the viewpoint of improving productivity and economy, the curable resin is preferably an ultraviolet curable resin.

Examples of the photocurable monomer for forming the ultraviolet curable resin include 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, and tetraethylene glycol diacrylate. , Tripropylene glycol diacrylate, neopentyl glycol diacrylate, 1,4-butanediol dimethacrylate, poly(butanediol) diacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, triethylene glycol diacrylate Diacrylate compounds such as, triisopropylene glycol diacrylate, polyethylene glycol diacrylate and bisphenol A dimethacrylate; trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol monohydroxytriacrylate and trimethylolpropane triethoxytriacrylate. And triacrylate compounds such as pentaerythritol tetraacrylate and di-trimethylolpropane tetraacrylate; and pentaacrylate compounds such as dipentaerythritol (monohydroxy) pentaacrylate. As the ultraviolet curable resin, a polyfunctional acrylate compound having a functionality of 5 or more may also be used. The polyfunctional acrylate compound may be used alone or in combination of two or more. Moreover, you may add a photoinitiator, a photosensitizer, a leveling agent, a diluent, etc. to the said polyfunctional acrylate compound.

Further, the first hard coat layer may be composed of a resin portion and a filler. When the first hard coat layer contains a filler, the pattern of the conductive layer can be made more difficult to be visually recognized. When the first hard coat layer contains a filler, tanned skin may occur, and when used in a liquid crystal display device, display light may be difficult to see. Therefore, from the viewpoint of making the yuzu skin less likely to occur, it is desirable that the first hard coat layer does not contain a filler and is composed of only the resin portion. Alternatively, it is preferable that the average particle diameter of the filler is smaller than the thickness of the first hard coat layer, and the filler does not project on the surface of the first hard coat layer.

The filler is not particularly limited, for example, silica, iron oxide, aluminum oxide, zinc oxide, titanium oxide, silicon dioxide, antimony oxide, zirconium oxide, tin oxide, cerium oxide, metal oxide such as indium-tin oxide. Material particles; resin particles such as silicone, (meth)acrylic, styrene, and melamine. More specifically, resin particles such as crosslinked poly(meth)acrylate can be used. The fillers may be used alone or in combination of two or more.

Further, the first and second hard coat layers may each contain various stabilizers, ultraviolet absorbers, plasticizers, lubricants or colorants.

(Refractive index adjusting layer: low refractive index layer and high refractive index layer)
The refractive index of the low refractive index layer is 1.40 or more and 1.55 or less. The high refractive index layer has a refractive index of 1.65 or more.

Each of the low refractive index layer and the high refractive index layer is appropriately formed so as to satisfy the above refractive index. By forming the refractive index layer having the above specific refractive index, it is possible to reduce the difference in the refractive index between the conductive layer and the second hard coat layer or the substrate film. The light transmittance of the conductive film can be further enhanced.

The material forming the refractive index adjusting layer is not particularly limited as long as it has a refractive index adjusting function, and is an inorganic material such as ZrO ₂ , TiO ₂ , SiO ₂ , MgF ₂ , Al ₂ O ₃ , or an acrylic resin or urethane. Organic materials such as resins, melamine resins, alkyd resins and siloxane polymers, or mixtures of these inorganic-organic materials are mentioned. The high refractive index layer may be formed as a hard coat layer. When the high refractive index layer is formed as a hard coat layer, a material having a refractive index of 1.65 or more is selected from the materials of the first and second hard coat layers described above, and the high refractive index is Layers can be formed.

The refractive index adjusting layer can be formed by a vacuum vapor deposition method, a sputtering method, an ion plating method or a coating method.

The thickness of the low refractive index layer is 21 nm or more and 30 nm or less. The high refractive index layer has a thickness of 0.4 μm or more and 2 μm or less. By forming the refractive index adjusting layer having the above-mentioned specific thickness, it is possible to reduce the difference in the refractive index between the conductive layer and the second hard coat layer or the substrate film. The light transmittance of the conductive film can be further enhanced.

(Conductive layer)
The thickness of the conductive layer is 21 nm or more and 35 nm or less. The conductive layer has a relatively large thickness. In the present invention, the color difference can be reduced and the resistance value can be reduced even though the thickness of the conductive layer is 21 nm or more.

The conductive layer is formed of a light-transmitting conductive material. The conductive material is not particularly limited, but examples thereof include In-based oxides such as IZO (indium zinc oxide) and ITO (indium tin oxide), SnO ₂ and Sn such as FTO (fluorine-doped tin oxide). -Based oxides, Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide), sodium, sodium-potassium alloys, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum -Lithium alloy, Al/Al ₂ O ₃ mixture, Al/LiF mixture, metal such as gold, CuI, Ag nanowire (AgNW), carbon nanotube (CNT) or conductive transparent polymer. The above conductive materials may be used alone or in combination of two or more.

From the viewpoint of further increasing the conductivity and further increasing the light transmissivity, the conductive material is an In-based oxide such as IZO (indium zinc oxide) or ITO (indium tin oxide), SnO ₂ , or FTO. Sn-based oxides such as (fluorine-doped tin oxide), Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide) are preferable, and ITO (indium tin oxide) is preferable. Is more preferable.

The thickness of the conductive layer is 21 nm or less, preferably 50 nm or less, and more preferably 30 nm or less.

When the thickness of the conductive layer is at least the above lower limit, the conductivity of the light transmissive conductive film can be further enhanced. When the thickness of the conductive layer is equal to or less than the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized. The surface resistance of the conductive layer is preferably 110Ω/□ or less, and more preferably 100Ω/□ or less.

Regarding the light transmittance of the light-transmitting conductive film, the total light transmittance in the visible light region is preferably 89% or more, more preferably 90% or more. The total light transmittance may be 85% or more. Regarding the color difference, the transmitted color difference is preferably 1.9 or less, more preferably 1.5 or less, and the reflected color difference is preferably 6.0 or less, more preferably 5.0 or less.

(Protective film)
The protective film is preferably composed of a base sheet and an adhesive layer.

The base material sheet preferably has high light transmittance. The material of the substrate sheet is not particularly limited, but examples thereof include polyolefin, polyether sulfone, polysulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. , Triacetyl cellulose, and cellulose nanofibers.

The pressure-sensitive adhesive layer can be composed of a (meth)acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a urethane-based adhesive or an epoxy-based adhesive. From the viewpoint of suppressing an increase in adhesive strength due to heat treatment, the adhesive layer is preferably composed of a (meth)acrylic adhesive.

The (meth)acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive obtained by adding a cross-linking agent, a tackifying resin, various stabilizers, etc. to the (meth)acrylic polymer as needed.

The (meth)acrylic polymer is not particularly limited, but is a (meth)acrylic copolymer obtained by copolymerizing a mixed monomer containing a (meth)acrylic acid ester monomer and another copolymerizable polymerizable monomer. It is preferably a polymer.

The (meth)acrylic acid ester monomer is not particularly limited, but is obtained by an esterification reaction between a primary or secondary alkyl alcohol having an alkyl group having 1 to 12 carbon atoms and (meth)acrylic acid ( A (meth)acrylic acid ester monomer is preferable, and specific examples thereof include ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

Examples of the other copolymerizable polymerizable monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate; Isobornyl (meth)acrylate, hydroxyalkyl (meth)acrylate, glycerin dimethacrylate, glycidyl (meth)acrylate, 2-methacryloyloxyethyl isocyanate, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid Functional monomers such as acids and fumaric acid may be mentioned. The above-mentioned other copolymerizable polymerizable monomers may be used alone or in combination.

The cross-linking agent is not particularly limited, and examples thereof include an isocyanate cross-linking agent, an epoxy cross-linking agent, a melamine cross-linking agent, a peroxide cross-linking agent, a urea cross-linking agent, a metal alkoxide cross-linking agent, and a metal chelate cross-linking agent. Agents, metal salt crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents, polyfunctional acrylates and the like. The crosslinking agents may be used alone or in combination of two or more.

The tackifying resin is not particularly limited, and examples thereof include petroleum-based resins such as aliphatic copolymers, aromatic copolymers, aliphatic/aromatic copolymers and alicyclic copolymers. Coumarone-indene type resin; terpene type resin; terpene phenol type resin; rosin type resin such as polymerized rosin; phenol type resin; xylene type resin. The tackifying resin may be a hydrogenated resin. The above tackifier resins may be used alone or in combination.

The thickness of the protective film is preferably 25 μm or more, more preferably 50 μm or more, preferably 300 μm or less, more preferably 200 μm or less. When the thickness of the protective film is not less than the above lower limit and not more than the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the examples below.

( Reference example 1)
(1) Preparation of light-transmissive conductive film Formation of hard coat layer;
100 parts by weight of urethane acrylate oligomer as a photo-curable monomer, 140 parts by weight of a mixed solvent of toluene and methyl isobutyl ketone (MIBK) as a diluting solvent, and 7 parts by weight of Irgacure 194 (manufactured by Ciba Specialty Chemicals) as a photoinitiator. And the mixture were stirred to prepare a coating liquid.

The coating liquid was applied to both surfaces of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.), which is a base film, and dried. After drying, the resin was cured by irradiating with ultraviolet rays of 200 mJ/cm ^{2 with} a high pressure mercury lamp to form a first hard coat layer having a thickness of 2 μm.

Formation of high refractive index layer;
An acrylate oligomer (“Rioduras TYZ” manufactured by Toyo Ink Co., Ltd.) in which ZrO ₂ nanoparticles were dispersed was prepared as a UV-curable hard coat liquid. This solution was applied to the surface of the base film opposite to the first hard coat layer and dried. After drying, the resin was cured by irradiating with ultraviolet rays of 200 mJ/cm ² from a high pressure mercury lamp to form a high refractive index layer having a refractive index of 1.65.

Lamination of protective film;
A protective film (thickness: 50 μm) was attached to the first hard coat layer from the pressure-sensitive adhesive layer side.

Formation of a low refractive index layer;
A SiO ₂ film was formed on the high refractive index layer by an AC magnetron sputtering method using a polycrystal having a Si purity of 99.9% as a Si target material. Specifically, the chamber is evacuated to 5×10 ⁻⁴ Pa or less, and then a mixed gas of Ar gas: 95% and oxygen gas: 5% is introduced into the chamber to form a SiO ₂ film having a thickness of 23 nm. The film was deposited to form a low index layer.

Formation of a conductive layer;
A transparent conductive layer that covers the entire surface of the low refractive index layer by DC magnetron sputtering using a sintered body material of indium oxide: 93% by weight and tin oxide: 7% by weight as a target material on the low refractive index layer. Was formed. Specifically, after the chamber was evacuated to 5×10 ⁻⁴ Pa or less, a mixed gas of Ar gas: 95% and oxygen gas: 5% was introduced into the chamber to form an ITO layer having a thickness of 22 nm. (Transparent conductive layer) was formed. The PET film having the ITO layer deposited thereon was heated in an oven at 150° C. for 60 minutes to obtain a light-transmitting conductive film. A resist was attached to the obtained film, and exposure and development were performed. Subsequently, etching, peeling, washing, and drying steps were performed in this order to pattern the ITO layer. Thereby, a patterned light-transmitting conductive film was obtained.

( Reference Example 2, Examples 3 to 7, Reference Examples 8 and 9 and Comparative Examples 1 to 7)
The thicknesses of the conductive layer, the low refractive index layer and the high refractive index layer were set as shown in Table 1 below, and the refractive indexes of the low refractive index layer and the high refractive index layer were set as shown in Table 1 below. A light transmissive conductive film was obtained in the same manner as in Reference Example 1 except that the above was set.

(Evaluation)
(1) Calculation of Thickness and Refractive Index of Each Layer The thickness (optical film thickness) and refractive index of each layer were calculated by measuring regular reflectance and performing optical simulation from the measured values. Specifically, regarding the reflectance measurement, a 5° specular reflection unit attached to a spectrophotometer (“U4100” manufactured by Hitachi, Ltd., or its equivalent) is attached, and the incident angle is 5° by using the specular reflection mode. The reflection spectrum at a wavelength of 200 to 800 nm (measurement range) was measured. In the measurement, a black tape (“NO200-50-21” manufactured by Yamato Co., Ltd.) was attached to the back surface of the sample in order to eliminate back surface reflection of the sample and reflection from the back surface side. The back surface side of the sample is the surface opposite to the transparent conductive layer. With the protective film removed, a black tape was attached to the back surface. Using optical simulation software ("WVASE32" manufactured by JA Woollam), fitting of the shape of the specular reflection spectrum and the position of the peak valley was performed to calculate the thickness and refractive index of each layer.

(2) Color Difference Regarding the color difference, the tint before and after the patterning of the ITO layer was measured, and the difference in tint due to the presence or absence of patterning was calculated based on JIS Z8729. Specifically, the tint of the film including the ITO layer was measured based on JIS Z8729 using a spectrophotometer (“MCPD-9800” manufactured by Otsuka Electronics Co., Ltd., or its equivalent). With respect to the film after patterning that did not include the ITO layer, the tint was measured by the same method as described above. The state of the sample is a state in which the protective film is peeled off from the light transmissive conductive film. It should be noted that light is incident from the ITO side, light emitted from the back surface is a transmitted tint, and light incident from the ITO layer side is a reflected tint.

(3) Surface resistance (Rs)
The surface resistance was measured by a four-terminal method using a surface resistance meter (“Loresta-EP” manufactured by MITSUBISHI CHEMICAL ANALYTECH, or its equivalent).

(4) Total light transmittance (TT)
The total light transmittance was measured based on JIS K7105 using a haze meter (“NDH-2000” manufactured by Nippon Denshoku Co., Ltd. or its equivalent).

1, 1A... Light transmissive conductive film 2, 2A... Base material 2a... First surface 2b... Second surface 3... Conductive layer 4... Low refractive index layer 5... High refractive index layer 6... Protective film 11... Base Material film 12... First hard coat layer 13... Second hard coat layer

Claims (3)

A conductive layer having optical transparency and conductivity,
A low refractive index layer and a high refractive index layer disposed on one surface side of the conductive layer,
The thickness of the conductive layer is 21 nm or more and 35 nm or less,
The thickness of the low refractive index layer is 21 nm or more and 30 nm or less,
The thickness of the high refractive index layer is 1.05 μm or more and 2 μm or less,
The ratio of the thickness of the high refractive index layer to the thickness of the low refractive index layer is 50 or more and 95 or less,
The low refractive index layer has a refractive index of 1.40 or more and 1.55 or less,
A light-transmissive conductive film, wherein the high refractive index layer has a refractive index of 1.67 or more. The surface resistance of the conductive layer is 110Ω/□ or less,
The light-transmissive conductive film according to claim 1, which has a total light transmittance of 89% or more. The light-transmissive conductive film according to claim 1, wherein the high refractive index layer has a thickness of 1.5 μm or more and 2 μm or less.

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