JP6803655B2 - Transparent laminated film, transparent conductive film, touch panel and display device - Google Patents

Description

The present invention relates to a transparent laminated film and a transparent conductive film used for a touch panel, and a touch panel and a display device using the transparent laminated film.

In recent years, in order to increase the area of the touch panel, the resistance value of the transparent conductive layer (transparent electrode layer) has been reduced, and the film thickness of the transparent conductive layer tends to be increased. When the film thickness of the transparent conductive layer is increased, the transmittance is lowered and the transmitted light and the reflected light are colored. Further, in the configuration in which the transparent conductive layer is patterned in a predetermined shape, the transmittance of the transparent conductive layer decreases and the reflectance increases, so that the reflection between the region where the transparent electrode layer exists and the region where the transparent conductive layer does not exist is reflected. There is also a problem that the rate difference becomes large and the pattern shape of the transparent conductive layer becomes easily visible.

Patent Document 1 discloses a laminate in which a transparent base material, a transparent layer, a high refractive index layer, a low refractive index layer, and a transparent conductive layer are laminated. In Patent Document 1, the refractive index and film thickness of the high refractive index layer and the low refractive index layer, and the reflected light in each of the transparent conductive layer existing region and the non-existing region, which are necessary for making the patterned transparent conductive layer invisible. The color coordinates and color difference of are described.

Japanese Patent No. 5574253

However, Patent Document 1 does not study any problems such as a decrease in transmittance and coloring of transmitted light due to a thickening of the transparent conductive layer.

Therefore, the present invention uses a transparent laminated film and a transparent conductive film which have high transmittance and can suppress coloring of reflected light and transmitted light even when the transparent conductive layer is thickened, and a transparent laminated film. It is an object of the present invention to provide a touch panel and a display device.

The transparent conductive film according to the present invention is provided with a high refractive index hard coat layer, a high refractive index layer, a low refractive index layer, and a transparent conductive layer on at least one surface of the substrate in order from the substrate side, and has a high refractive index hard. The refractive index of the coat layer is 1.58 or more and 1.71 or less, the refractive index of the high refractive index layer is 1.65 or more and 1.76 or less, and the film thickness of the high refractive index layer is 10 nm or more and 50 nm or less. The refractive index of the low refractive index layer is 1.45 or more and 1.55 or less, the film thickness of the low refractive index layer is 30 nm or more and 50 nm or less, and the refractive index of the transparent conductive layer is 1.80 or more and 2.00 or less. In addition, the thickness of the transparent conductive layer is 25 nm or more and 35 nm or less, and the color coordinates a ^* and b ^* in the L ^* a ^* b ^* color system of the reflected light on the transparent conductive layer side of the transparent conductive film are set. respectively with ^a _{* 1} and ^b _{* 1,} the color coordinates ^{a *} and ^{b *} in the transmitted light in the ^L * ^a * ^{b *} color system of the transparent conductive film, and each of ^a _{* 2} and ^b _{* 2,} a transparent conductive at 550nm When the transmittance of the film is T, the following formula is satisfied.
0 . 52 <a ^* ₁ < 1.77
− 0.75 <a ^* ₂ < −0.47
− 7.95 <b ^* ₁ < -3.26
2.03 <b ^* ₂ < 3.28
88% <T

Further, the transparent laminated film according to the present invention is provided with a high refractive index hard coat layer, a high refractive index layer, and a low refractive index layer in this order from the substrate side on at least one surface of the substrate, and has a transmittance of 1.80. It is used for a transparent conductive film having a transparent conductive layer having a thickness of 25 nm or more and 35 nm or less, and has a high refractive index hard coat layer having a refractive index of 1.58 or more and 1.71 or less. The high refractive index layer has a refractive index of 1.65 or more and 1.76 or less, the high refractive index layer has a thickness of 10 nm or more and 50 nm or less, and the low refractive index layer has a refractive index of 1.45 or more. .55 or less, the thickness of the low refractive index layer is 30 nm or more and 50 nm or less, and the L ^* a ^* b ^* color coordinates a ^* in the color system of the reflected light on the low refractive index layer side of the transparent laminated film Let b ^* be a ^* ₃ and b ^* ₃ , respectively, and let L ^* a ^* b ^* color coordinates a ^* and b ^* in the transparent laminated film be a ^* ₄ and b ^* ₄ , respectively. When the transmittance of the transparent laminated film at 550 nm is t, the following formula is satisfied.
-0.25 <a ^* ₃ <0.25
-0.05 <a ^* ₄ <0.05
0 <b ^* ₃ <3
-0.5 <b ^* ₄ <0
88% <t

According to the present invention, a transparent laminated film and a transparent conductive film which have high transmittance and can suppress coloring of reflected light and transmitted light even when the transparent conductive layer is thickened, and a transparent laminated film are used. A touch panel and a display device can be provided.

Cross-sectional view showing a configuration example of an image display device including a touch panel Cross-sectional view showing an example of the layer structure of the laminated film used for the transparent conductive film shown in FIG.

FIG. 1 is a cross-sectional view showing a configuration example of an image display device including a touch panel.

The image display device 1 includes a backlight 4, a polarizing plate 5, a liquid crystal panel 6, a polarizing plate 7, and transparent conductive films 9a and 9b in this order from the back side (lower side of FIG. 1) to the observation side (upper side of FIG. 1). , The cover glass 12 is provided. The polarizing plate 7, the transparent conductive films 9a and 9b, and the cover glass 12 are bonded to each other via adhesive layers 8, 10 and 11 such as a transparent optical adhesive film. FIG. 1 shows a configuration example in which a polarizing plate 7 and a transparent conductive film 9a are bonded by a so-called air gap method in which an adhesive layer 8 is provided only on a peripheral edge portion and an air layer is interposed.

FIG. 2 is a cross-sectional view showing an example of the layer structure of the laminated film used for the transparent conductive film shown in FIG.

The transparent conductive films 9a and 9b shown in FIG. 2 include a transparent laminated film 20 and a transparent conductive layer 25 laminated on the transparent laminated film 20. The transparent laminated film 20 includes a transparent base material 21, a high refractive index hard coat layer 22, a high refractive index layer 23, and a low refractive index layer 24. Although not shown, the transparent electrode is formed by patterning the transparent conductive layer 25 into a predetermined shape.

Hereinafter, the details of each layer included in the transparent conductive film will be described.

(Transparent base material)
The transparent base material 21 is a film that serves as a base for a transparent conductive film, and is formed of a material having excellent transparency of visible light. Examples of the material for forming the transparent base material 21 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyamides such as nylon 6 and nylon 66, polyimides, polyarylates, polycarbonates and polyacrylates. Transparent resins such as polyether sulfone, polyethylene sulfone, and cellulose triacetate, and inorganic glass can be used. Further, the transparent base material 21 may be a composite film in which a plurality of materials are laminated. The thickness of the transparent base material 21 is not particularly limited, but is preferably 10 to 200 μm.

(High refractive index hard coat layer)
The high refractive index hard coat layer 22 can be formed by a wet coating method. High refractive index hard coat layer 22, and ionizing radiation-curable resin such as acrylate monomer, and a high refractive index particles, and a transparent substrate a high refractive index hard coat layer forming coating liquid containing a polymerization initiator It can be formed by applying and curing. As the acrylate monomer, for example, pentaerythritol triacrylate (manufactured by Kyoeisha Chemical Co., Ltd., manufactured by Shin-Nakamura Chemical Industry Co., Ltd., manufactured by Sartomer) can be used. As the high-refractive particles, zirconia fine particles, titanium fine particles and the like can be used.

The refractive index of the high refractive index hard coat layer 22 is 1.58 to 1.71. When the refractive index of the high refractive index hard coat layer 22 is less than 1.58, the transmittance of the transparent conductive layer 25 after film formation decreases. On the other hand, when the refractive index of the high refractive index 22 hard coat layer is larger than 1.71, the reflected light and transmitted light are colored after the transparent conductive layer 25 is formed.

The film thickness of the high refractive index hard coat layer 22 is not particularly limited as long as it can impart the mechanical strength required for the transparent laminated film 20 and suppress curling of the transparent laminated film 20. The film thickness of the high refractive index hard coat layer is, for example, 1 to 10 μm.

(High refractive index layer)
The high refractive index layer 23 can be formed by a wet coating method. The high refractive index layer 23 is coated with a coating liquid for forming a high refractive index layer 21 containing an ionizing radiation curable resin such as an acrylate monomer, high refractive index fine particles, and a polymerization initiator. It can be formed by curing the film. Examples of the high refractive index fine particles include zirconium oxide, titanium oxide, niobium oxide, antimony trioxide, antimony pentoxide, tin oxide, ATO (antimony-doped tin oxide), indium oxide, ITO (tin-doped indium oxide), zinc oxide and the like. Fine particles made of a high refractive index material can be used. As the acrylate monomer, those exemplified for the high refractive index hard coat layer can be used.

The refractive index of the high refractive index layer 23 is 1.65 to 1.76. When the refractive index of the high refractive index layer 23 is less than 1.65, coloring occurs after the film formation of the transparent conductive layer 25. Further, for the convenience of coating the high refractive index fine particles into a liquid, the refractive index of the obtained high refractive index layer 23 is about 1.76, which is a realistic upper limit value.

The film thickness of the high refractive index layer 23 is 10 to 50 nm. If the film thickness of the high refractive index layer 23 is out of this range, coloring occurs after the transparent conductive layer is formed. Further, when the high refractive index layer 23 is formed by the wet coating method, the film thickness is about 10 nm, which is a realistic lower limit value.

(Low refractive index layer)
The low refractive index layer 24 can be formed by a wet coating method. The low refractive index layer 24 is coated by applying a coating liquid for forming a low refractive index layer containing an ionizing radiation curable resin such as an acrylate monomer having an ether bond and a polymerization initiator to the high refractive index layer 23. It can be formed by curing the film by photopolymerization. Examples of the acrylate compound having an ether bond include tripropylene glycol diacrylate (trade name: APG-200, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), propoxy (3) trimethylolpropane triacrylate (trade name: SR492, Tomoe Kogyo Co., Ltd.). (Manufactured by the company), propoxy (6) trimethylolpropane triacrylate (trade name: CD501, manufactured by Tomoe Kogyo Co., Ltd.) and the like can be used.

The refractive index of the low refractive index layer 24 is 1.45 to 1.55. When the refractive index of the low refractive index layer 24 is less than 1.45, coloring occurs after the film formation of the transparent conductive layer 25. Further, when the refractive index of the low refractive index layer 24 exceeds 1.55, the transmittance of the transparent conductive layer 25 after film formation decreases.

The film thickness of the low refractive index layer 24 is 30 to 50 nm. When the film thickness of the low refractive index layer 24 is less than 30 nm, the transmittance of the transparent conductive layer 25 after film formation decreases. Further, when the film thickness of the low refractive index layer 24 exceeds 50 nm, coloring occurs after the transparent conductive layer 25 is formed.

Examples of the binder resin for forming the high refractive index hard coat layer, the high refractive index layer, and the low refractive index layer described above include, for example, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylol. Triacrylates such as propanetriacrylate, tris2-hydroxyethylisocyanurate triacrylate, glycerin triacrylate, trifunctional acrylate compounds such as pentaerythritol triacrylate, dipentaerythritol triacrylate, dimethylolpropanetriacrylate, and pentaerythritol tetra. Trifunctional or higher functional acrylate compounds such as acrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, ditrimethylolpropane pentaacrylate, dipentaerythritol hexaacrylate, and ditrimethylolpropane hexaacrylate, and these. Examples thereof include a polyfunctional acrylate compound in which a part of the acrylate is replaced with an alkyl group or ε-caprolactone.

Examples of the polymerization initiators described above include 2,2-ethoxyacetophenone, 1-hydroxycyclohexylphenylketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler ketone, and the like. Examples thereof include acetophenone and 2-chlorothioxanthone. These may be used alone or in combination of two or more types.

When the layer is formed by the wet coating method, the flow coating method, the spray coating method, the roll coating method, the gravure roll coating method, the air doctor coating method, the plaid coating method, the wire doctor coating method, the knife coating method, and the reverse coating method. After applying the coating liquid by a known wet coating method such as transfer coating method, microgravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, die coating method, etc., the coating film is applied. Let it cure. As a method for curing the coating film of the coating liquid, for example, ultraviolet irradiation, heating, or the like can be used. In the case of ultraviolet irradiation, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a fusion lamp and the like can be used. The amount of ultraviolet irradiation is usually about 100 to 800 mJ / cm ² .

(Transparent conductive layer)
The transparent conductive layer 25 is formed by using a transparent conductive material having a refractive index of 1.80 to 2.00, such as ITO (Indium Tin Oxide), indium oxide, zinc oxide, tin oxide, and titanium oxide. The method for forming the transparent conductive layer 25 is not particularly limited, but a film can be formed by a sputtering method, a vacuum vapor deposition method, an ion plate method, a chemical vapor deposition method (CVD method), or the like. After the film formation of the transparent conductive layer 25, in order to crystallize the amorphous material, an annealing treatment is generally performed at a temperature of 100 to 170 ° C. for 5 to 120 minutes.

The surface resistance value of the transparent conductive layer 25 after heating the transparent conductive films 9a and 9b at 100 to 170 ° C. for 5 to 120 minutes is 100Ω / □ or less. If the surface resistance value of the transparent electrode layer 25 after the annealing treatment under the above conditions becomes larger than 100Ω / □, it becomes difficult to apply it to a large touch panel.

The film thickness of the transparent conductive layer 25 is 25 to 35 nm. If the film thickness of the transparent conductive layer 25 is less than 25 nm, it becomes impossible to reduce the resistance value of the transparent conductive layer 25, which makes it difficult to apply it to a large-area touch panel. Further, when the film thickness of the transparent conductive layer 25 exceeds 35 nm, the transmittance of the transparent conductive layer 25 decreases.

In the transparent laminated film 20 described above, the transparent laminated film 20 wound in a roll shape is pulled out and conveyed, and layers are sequentially formed on one surface of the transparent base material 21 to obtain the obtained transparent laminated film 20. It can be formed by the roll-to-roll method of rewinding. After that, the transparent conductive films 9a and 9b can be obtained by forming the transparent conductive layer 25 on the low refractive index layer 24 while pulling out and transporting the wound transparent laminated film 20.

(Characteristics of transparent conductive film)
The transparent conductive films 9a and 9b obtained by setting the refractive index and the film thickness of the high refractive index hard coat layer 22, the high refractive index layer 23, the low refractive index layer 24 and the transparent conductive layer 25 within the above ranges can be obtained. , The following conditional equations (1) to (5) are satisfied at the same time.
0.52 <a ^* ₁ < 1.77 ... (1)
− 0.75 <a ^* ₂ < −0.47 ... (2)
− 7.95 <b ^* ₁ < -3.26 ... (3)
2.03 <b ^* ₂ < 3.28 ... (4)
88% <T ... (5)
here,
a ^* ₁ : L ^* a ^* b ^* of the reflected light on the transparent conductive layer side ^* Color coordinates in the color system a ^*
b ^* ₁ : L ^* a ^* b ^* of the reflected light on the transparent conductive layer side ^* Color coordinates in the color system b ^*
a ^* ₂ : L of transmitted light ^* a ^* b ^* Color coordinates in the color system a ^*
b ^* ₂ : Transmitted light L ^* a ^* b ^* Color coordinates in the color system b ^*
T: The transmittance of light having a wavelength of 550 nm of the transparent conductive film.

If the conditional expressions (1) and (3) are not satisfied at the same time, the reflected light in the region where the transparent conductive layer 25 exists is colored. If the conditional expressions (2) and (4) are not satisfied at the same time, the light transmitted through the region where the transparent conductive layer 25 exists is colored. Further, when the conditional expression (5) is not satisfied, the reflected light in the region where the transparent conductive layer 25 is present increases relatively, and the reflectance difference between the region where the transparent conductive layer 25 exists and the region where the transparent conductive layer 25 does not exist becomes large and transparent. The pattern of the conductive layer 25 is easily visible.
(Characteristics of transparent laminated film)
Further, the transparent laminated film 20 obtained by setting the refractive index and the film thickness of the high refractive index hard coat layer 22, the high refractive index layer 23 and the low refractive index layer 24 within the above ranges can be obtained by the following conditional expression ( 6) to (10) are satisfied at the same time.
-0.25 <a ^* ₃ <0.25 ... (6)
-0.05 <a ^* ₄ <0.05 ... (7)
0 <b ^* ₃ <3 ... (8)
-0.5 <b ^* ₄ <0 ... (9)
88% <t ... (10)

here,
a ^* ₃ : L ^* a ^* b ^* of the reflected light on the low refractive index layer side ^* Color coordinates in the color system a ^*
b ^* ₃ : L ^* a ^* b ^* of the reflected light on the low refractive index layer side ^* Color coordinates in the color system b ^*
a ^* ₄ : Transmitted light L ^* a ^* b ^* Color coordinates in the color system a ^*
b ^* ₄ : Transmitted light L ^* a ^* b ^* Color coordinates in the color system b ^*
t: The transmittance of light having a wavelength of 550 nm of the transparent laminated film.

If the condition formulas (6) and (8) are not satisfied at the same time, the reflected light in the region where the transparent conductive layer 25 exists is colored after the transparent conductive layer 25 is formed on the low refractive index layer 24. If the conditional expressions (7) and (9) are not satisfied at the same time, after the transparent conductive layer 25 is formed on the low refractive index layer 24, the light transmitted through the region where the transparent conductive layer 25 exists is colored. If the condition formula (10) is not satisfied, after the transparent conductive layer 25 is formed on the low refractive index layer 24, the reflected light in the region where the transparent conductive layer 25 is located increases relatively, and the transparent conductive layer 25 becomes thick. The difference in reflectance between the existing region and the non-existing region becomes large, and the pattern of the transparent conductive layer 25 becomes easily visible.

As described above, the transparent conductive layer 25 is set by setting the refractive index and the film thickness of the high refractive index hard coat layer 22, the high refractive index layer 23, the low refractive index layer 24, and the transparent conductive layer 25 within the above ranges. The transparent laminated film 20 and the transparent conductive films 9a and 9b, which have a high transmittance and can suppress the coloring of the reflected light and the transmitted light, can be realized even when the film is thickened.

Hereinafter, examples of concrete implementation of the present invention will be described.

The materials used in Examples 1 to 11 and Comparative Examples 1 to 14 are as follows.

[Transparent substrate]
Polyethylene terephthalate film Product name: 50UH13 (manufactured by Toray Industries, Inc.), thickness 50 μm

[Coating liquid for forming a high refractive index hard coat layer]
UV curable functional hard coat agent Product name: Rio Duras (registered trademark) TYZ series (manufactured by Toyo Ink Co., Ltd., high refraction particles: ZrO ₂ )
More specifically, TYZ65 (Examples 1, 3 to 9, Comparative Examples 1 to 12), TYZ63 (Example 2), TYZ58 (Example 10), TYZ71 (Example 11), TYZ57 (Comparative Example 13). , TYZ72 (Comparative Example 14) was used.

[Coating liquid for forming a high refractive index layer]
UV curable functional hard coat agent Brand name: Rio Duras (registered trademark) TYZ series (manufactured by Toyo Ink Co., Ltd., high refractive particles: ZrO ₂ ) or TYT series (manufactured by Toyo Ink Co., Ltd., high refractive particles: TiO ₂₎ )
More specifically, TYZ71 (Examples 1, 4 to 10, Comparative Examples 3 to 14), TYZ65 (Example 2), TYZ76 (Example 3), TYZ72 (Example 11), TYZ60 (Comparative Example 1). , TYT90 (Comparative Example 2) was used.

[Coating liquid for forming a low refractive index layer (Examples 1 to 3, 6 to 11, Comparative Examples 1, 2, 5 to 14)]
・ Propylene glycol (6) Trimethylolpropane triacrylate Product name: CD501 (manufactured by Tomoe Kogyo Co., Ltd.) 100 parts by mass ・ Photopolymerization initiator: Irgacure 184 (manufactured by BASF) 5 parts by mass ・ Solvent: Methylethylketone (Toyo Ink Co., Ltd.) (G) 50 parts by mass Propylene glycol monomethyl ether (Toyo Ink Co., Ltd.) 50 parts by mass

[Coating liquid for forming a low refractive index layer (Example 4)]
・ 1,2-Diacryloxymethyl-perfluorocyclohexane Product name: LINK-102A (manufactured by Kyoeisha Chemical Co., Ltd.) 100 parts by mass ・ Photopolymerization initiator: Irgacure 184 (manufactured by BASF) 5 parts by mass ・ Solvent: Methylethylketone (manufactured by BASF) Toyo Ink Co., Ltd.) 50 parts by mass Propylene glycol monomethyl ether (Toyo Ink Co., Ltd.) 50 parts by mass

[Coating liquid for forming a low refractive index layer (Example 5)]
・ Bisphenol AEO 3.8 mol Additive diacrylate Brand name: Viscote # 700HV (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 100 parts by mass ・ Photopolymerization initiator: Irgacure 184 (manufactured by BASF) 5 parts by mass ・ Solvent: Methyl ethyl ketone (Toyo) Ink Co., Ltd.) 50 parts by mass Propylene glycol monomethyl ether (Toyo Ink Co., Ltd.) 50 parts by mass

[Coating liquid for forming a low refractive index layer (Comparative Example 3)]
・ 1H, 1H, 5H-Octafluoropentyl methacrylate Product name: Viscoat 8FM (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 100 parts by mass ・ Photopolymerization initiator: Irgacure 184 (manufactured by BASF) 5 parts by mass ・ Solvent: Methylethylketone (Toyo) Ink Co., Ltd.) 50 parts by mass Propylene glycol monomethyl ether (Toyo Ink Co., Ltd.) 50 parts by mass

[Coating liquid for forming a low refractive index layer (Comparative Example 4)]
-UV curable functional hard coat agent Product name: Rio Duras (registered trademark) TYZ65 (manufactured by Toyo Ink Co., Ltd., high refraction particles: ZrO ₂ )

(Preparation of transparent laminated film)
A high-refractive index hard coat layer-forming coating liquid was applied to one surface of the transparent substrate so that the film thickness after drying was 1.5 μm, and the mixture was dried. Then, the coating film was cured by irradiating with ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb) to form a high refractive index hard coat layer.

Next, a coating liquid for forming a high refractive index layer was applied onto the high refractive index hard coat layer so that the film thickness after drying would be the film thickness shown in Table 1, and dried. Then, the coating film was cured by irradiating with ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb) to form a high refractive index layer.

Next, a coating liquid for forming a low refractive index layer was applied onto the high refractive index layer so that the film thickness after drying was the film thickness shown in Table 1, and dried. Then, the coating film was cured by irradiating with ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb) to form a low refractive index layer.

(Making a transparent conductive film)
Next, a transparent conductive layer made of ITO was formed on the low refractive index layer. The transparent conductive layer was formed into a film thickness as shown in Table 1 by performing sputtering in a vacuum using a DC magnetron sputtering apparatus. In Examples 1 to 11 and Comparative Examples 1 to 10, 13 and 14, ITO having a tin content of 5% by mass was used as the sputtering target, and in Comparative Example 11, an ITO having a tin content of 3% by mass was used. In Comparative Example 12, ITO having a tin content of 7% by mass was used. After the film was formed, it was annealed at 150 ° C. for 1 hour to obtain a transparent conductive film.

Further, in Examples 1 to 11, Comparative Examples 1 to 8 and 13 to 14, the color coordinates of the reflected light and the transmitted light (a ^* _3, b ^* ₃ described above, for the transparent laminated film before the formation of the transparent conductive layer). a ^* ₄ , b ^* ₄ ), the transmittance of light at 550 nm was measured, and for the transparent conductive film after the transparent conductive layer was formed, the color coordinates of the reflected light and transmitted light (a ^* ₁ , b ^* ₁ , a ^* _2). , B ^* ₂ ), the transmittance (t, T) of light at 550 nm, and the surface resistance value were measured. Regarding the remaining Comparative Examples 9 to 12, the color coordinates of the reflected light and the transmitted light (a ^* ₃ , b ^* ₃ , a ^* ₄ , b ^* ₄ ) and 550 nm light of the transparent conductive film after the transparent conductive layer was formed. The transmittance (T) and the surface resistance value of the above were measured. The measurement conditions are as follows.

[Optical characteristics (a ^* , b ^* , t, T)]
The values of the color coordinates a ^* and b ^* were measured by irradiating light from the transparent conductive layer side at an incident angle of 5 ° and using an angle-variable absolute reflection measuring device (U-4100; manufactured by Hitachi, Ltd.). The transmittances t and T were measured using light having a wavelength of 550 nm.

[Surface resistance value]
The surface resistance value was measured at an applied voltage of 10 V using a resistivity meter (Loresta GP MCP-T610 type; Mitsubishi Chemical Analytech Co., Ltd.).

Table 1 shows the refractive index, the film thickness, and the measured values before and after the formation of the transparent conductive layer of each of the layers of Examples 1 to 11 and Comparative Examples 1 to 14.

As shown in Table 1, in Examples 1 to 11, the refractive index and the film thickness of the high refractive index hard coat layer, the high refractive index layer, the low refractive index layer and the transparent conductive layer were set within the above ranges. It was confirmed that the color coordinate values and the transmittance were within a preferable range both before and after the formation of the transparent electrode layer, the coloration of the reflected light and the transmitted light was suppressed, and the light transmittance was high. It was. Further, in Examples 1 to 11, the surface resistance value was also less than 100Ω / □, and it was confirmed that the surface resistance value was suitable for a large touch panel.

On the other hand, in Comparative Examples 1 to 4, 6 to 8, 13 and 14, any one of the refractive index and the film thickness of the high refractive index hard coat layer, the high refractive index layer and the low refractive index layer is within the above range. As a result, in the transparent conductive film after forming the transparent conductive layer, the value of the color coordinates deviates from the preferable range, and the reflected light and the transmitted light are colored, or the transmittance is lowered.

Further, in Comparative Example 5, an attempt was made to form a high-refractive index layer with a film thickness of 5 nm by a wet coating method, but the film was too thin to be formed by the wet coating method, and a sample could be obtained. There wasn't.

Further, in Comparative Examples 9 to 12, the refractive index and the film thickness of the high refractive index hard coat layer, the high refractive index layer, and the low refractive index layer are the same as those in Example 1, but the refractive index or the film thickness of the transparent conductive layer is the same. Is out of the above range. From the comparison between Example 1 and Comparative Examples 9 to 12, a transparent laminated film in which all of the refractive index and the film thickness of the high refractive index hard coat layer, the high refractive index layer, and the low refractive index layer are within the above-mentioned ranges can be obtained. It was confirmed that it is suitable for a transparent conductive film having a transparent conductive layer having a refractive index of 1.80 or more and 2.00 or less and a film thickness of 25 nm or more and 35 nm or less. On the other hand, in Comparative Example 9, the surface resistance value exceeded 100 Ω / □ because the film thickness of the transparent conductive layer was too thin. In Comparative Example 10, the transparent conductive layer was too thick, so that the reflected light and the transmitted light were colored, and the transmittance was also low. In Comparative Example 11, since the transparent conductive layer was formed by using ITO having a lower tin content than in Examples 1 to 11, the surface resistance value exceeded 100 Ω / □. In Comparative Example 12, the transparent conductive layer had an excessively high refractive index, so that the reflected light and the transmitted light were colored, and the transmittance was also low.

From the above, it has been confirmed that according to the present invention, a transparent laminated film and a transparent conductive film having high transmittance and capable of suppressing coloring of reflected light and transmitted light can be realized even when the transparent conductive layer is thickened. It was.

The present invention can be used for an image device or the like provided with a touch panel.

1 Image display device 4 Backlight 5 Plate plate 6 Liquid crystal panel 7 Plate plate 8 Adhesive layer 9a, 9b Transparent conductive film 10 Adhesive layer 11 Adhesive layer 12 Cover glass 20 Transparent laminated film 21 High refractive index hard coat layer 22 High refractive index layer 24 Low refractive index layer 25 Transparent conductive layer

Claims (5)

A transparent conductive film provided with a high refractive index hard coat layer, a high refractive index layer, a low refractive index layer, and a transparent conductive layer on at least one surface of the base material in this order from the base material side.
The refractive index of the high refractive index hard coat layer is 1.58 or more and 1.71 or less.
The refractive index of the high refractive index layer is 1.65 or more and 1.76 or less, and the film thickness of the high refractive index layer is 10 nm or more and 50 nm or less.
The refractive index of the low refractive index layer is 1.45 or more and 1.55 or less, and the film thickness of the low refractive index layer is 30 nm or more and 50 nm or less.
The refractive index of the transparent conductive layer is 1.80 or more and 2.00 or less, and the film thickness of the transparent conductive layer is 25 nm or more and 35 nm or less.
The color coordinates a ^* and b ^* of the reflected light on the transparent conductive layer side of the transparent conductive film in the L ^* a ^* b ^* color system are set to a ^* ₁ and b ^* ₁ , respectively, and the transmissive light of the transparent conductive film is transmitted. When the color coordinates a ^* and b ^* in the L ^* a ^* b ^* color system of light are a ^* ₂ and b ^* ₂ , respectively, and the transmittance of the transparent conductive film at 550 nm is T, the following equation is satisfied. , Transparent conductive film.
0.52 <a ^* ₁ < 1.77
− 0.75 <a ^* ₂ < −0.47
− 7.95 <b ^* ₁ < -3.26
2.03 <b ^* ₂ < 3.28
88% <T A high refractive index hard coat layer, a high refractive index layer, and a low refractive index layer are provided on at least one surface of the base material in this order from the base material side, and the refractive index is 1.80 or more and 2.00 or less, and the film thickness is high. A transparent laminated film used for a transparent conductive film having a transparent conductive layer of 25 nm or more and 35 nm or less.
The refractive index of the high refractive index hard coat layer is 1.58 or more and 1.71 or less.
The refractive index of the high refractive index layer is 1.65 or more and 1.76 or less, and the film thickness of the high refractive index layer is 10 nm or more and 50 nm or less.
The refractive index of the low refractive index layer is 1.45 or more and 1.55 or less, and the film thickness of the low refractive index layer is 30 nm or more and 50 nm or less.
The L ^* a ^* b ^* color coordinates a ^* and b ^* of the reflected light on the low refractive index layer side of the transparent laminated film are set to a ^* ₃ and b ^* ₃ , respectively, and the transmittance of the transparent laminated film is transmitted. When the color coordinates a ^* and b ^* in the L ^* a ^* b ^* color system of light are a ^* ₄ and b ^* ₄ , respectively, and the transmittance of the transparent laminated film at 550 nm is t, the following equation is satisfied. , Transparent laminated film.
-0.25 <a ^* ₃ <0.25
-0.05 <a ^* ₄ <0.05
0 <b ^* ₃ <3
-0.5 <b ^* ₄ <0
88% <t The transparent conductive film according to claim 1, wherein the surface resistance value on the transparent conductive layer side after annealing the transparent conductive film is 100 Ω / □ or less. A touch panel comprising the transparent conductive film according to claim 1. A display device comprising the transparent conductive film according to claim 1.