JP6846984B2 - Transparent conductive film and image display device - Google Patents

Description

The present invention relates to a transparent conductive film and an image display device including the transparent conductive film.

Conventionally, it is known that an image display device including a touch panel and an image display element includes a touch panel film in which a transparent conductive layer made of indium tin oxide composite oxide (ITO) is formed on a transparent base material. As such a touch panel film, a double-sided transparent conductive film in which ITO layers are arranged on both sides of a transparent base material is described in, for example, Patent Document 1.

By the way, since an image display element such as a liquid crystal cell generates an electromagnetic wave, the image display device is desired to have an electromagnetic wave shielding effect of shielding the electromagnetic wave. Then, in the resistance film type touch panel, it is known that the ITO structure in which two ITO films are arranged to face each other has an electromagnetic wave shielding effect (see, for example, Non-Patent Document 1).

In particular, Non-Patent Document 1 describes that the ITO film needs to be thickened in order to reduce the resistance value of the ITO film, but as a result, the light transmittance is lowered. Further, it is described that if the resistance value of only one ITO film (for example, about 10Ω) is lowered, a good electromagnetic wave shielding effect can be obtained even if the resistance value of the other ITO film is increased.

From these results, Non-Patent Document 1 transmits light while exhibiting a good electromagnetic wave shielding effect by lowering the resistance value of only one ITO film and increasing the resistance value of the other ITO film. It discloses that the rate decrease can be suppressed.

Japanese Unexamined Patent Publication No. 2013-99924

Nozomi Harada, "Electromagnetic Wave Shielding Effect of Resistive Film Touch Panel Sensor", Institute of Electrical Engineers of Japan, Vol. 128, No. 7, 2008, p. 312-313

By the way, in a touch panel film (double-sided transparent conductive film) used in a capacitance method having good durability and few malfunctions, two ITO layers arranged on both sides are etched into an electrode pattern shape. To. Then, in order to suppress the visibility of the electrode pattern, an optical adjustment layer is provided between the ITO layer and the transparent base material.

In this case, since the double-sided transparent conductive film further includes an optical adjusting layer, the light transmission is lowered.

The present invention provides a transparent conductive film and an image display device having an electromagnetic wave shielding effect and having good light transmittance while suppressing the visibility of an electrode pattern.

The present invention [1] includes a first transparent conductive layer, a first optical adjusting layer, a transparent base material, a second optical adjusting layer, and a second transparent conductive layer in this order, and the surface resistance value of the second transparent conductive layer is determined. The surface resistance value of the first transparent conductive layer is larger than the surface resistance value of the first transparent conductive layer, the surface resistance value of the first transparent conductive layer is 10 Ω / □ or more and 70 Ω / □ or less, and the surface resistance value of the second transparent conductive layer is. A transparent conductive film having a refractive index of 50 Ω / □ or more and 150 Ω / □ or less and having a refractive index of the second optical adjusting layer smaller than that of the first optical adjusting layer is included.

The present invention [2] includes the transparent conductive film according to [1], wherein the thickness of the second transparent conductive layer is thinner than the thickness of the first transparent conductive layer.

In the present invention [3], the refractive index of the first optical adjustment layer is 1.65 or more and 1.75 or less, and the refractive index of the second optical adjustment layer is 1.60 or more and 1.70 or less. The transparent conductive film according to [1] or [2].

The present invention [4] is characterized in that the thickness of the first optical adjustment layer and the second optical adjustment layer are both 100 nm or less, according to any one of [1] to [3]. Includes the above-mentioned transparent conductive film.

In the present invention [5], the first transparent conductive layer and the second transparent conductive layer are both patterned, and the first transparent conductive layer has a first pattern that is long in one direction, and the second transparent is provided. The conductive layer includes a second pattern that is long in the orthogonal direction orthogonal to the one direction, and the one-way length of the first pattern is longer than the length in the orthogonal direction of the second pattern, [1] to [4]. The transparent conductive film according to any one of the above items is included.

In the present invention [6], the transparent conductive film according to any one of [1] to [5] and an image display element arranged on the first transparent conductive layer side of the transparent conductive film are provided. Includes an image display device.

According to the transparent conductive film of the present invention, a first transparent conductive layer, a first optical adjusting layer, a transparent base material, a second optical adjusting layer, and a second transparent conductive layer are provided in this order. Therefore, when the first transparent conductive layer and the second transparent conductive layer are patterned, the visibility of the first transparent conductive layer and the second transparent conductive layer can be suppressed.

Further, since the surface resistance value of the first transparent conductive layer is 10 Ω / □ or more and 70 Ω / □ or less, the transparent conductive film includes a transparent conductive layer having a small surface resistance value. Therefore, the transparent conductive film can exhibit a good electromagnetic wave shielding effect.

Further, since the surface resistance value of the second transparent conductive layer is larger than the surface resistance value of the first transparent conductive layer and is 50 Ω / □ or more and 150 Ω / □ or less, the second transparent conductive layer is made of the first transparent conductive layer. It can be made thinner than the layer. Further, the refractive index of the second optical adjustment layer is lower than the refractive index of the first optical adjustment layer. Therefore, the light transmittance of the transparent conductive film can be improved.

According to the image display device of the present invention, it has an electromagnetic wave shielding effect, and has good light transmission while suppressing the visibility of the patterned first transparent conductive layer and second transparent conductive layer.

FIG. 1 shows a cross-sectional view of an embodiment of the transparent conductive film of the present invention. FIG. 1 shows a cross-sectional view of a touch panel film in which the transparent conductive film shown in FIG. 1 is patterned. 3A to 3B are touch panel films shown in FIG. 3, FIG. 3A is a plan view showing an electrode pattern of a first transparent conductive layer, and FIG. 3B is a bottom surface showing an electrode pattern of a second transparent conductive layer. The figure is shown. FIG. 4 shows an image display device including the transparent conductive film shown in FIG. 5A to 5B are modifications of the touch panel film of the present invention (the electrode pattern of the transparent conductive layer includes a plurality of continuous rectangular patterns), and FIG. 5A shows the electrodes of the first transparent conductive layer. A plan view showing the pattern, FIG. 5B shows a bottom view showing the electrode pattern of the second transparent conductive layer.

<One Embodiment of Transparent Conductive Film>
An embodiment of the transparent conductive film of the present invention will be described below with reference to the drawings. In FIG. 1, the vertical direction of the paper surface is the vertical direction (thickness direction, first direction), the upper side of the paper surface is the upper side (one side in the thickness direction, one side in the first direction), and the lower side of the paper surface is the lower side (thickness direction). The other side, the other side in the first direction). The left-right direction of the paper is the left-right direction (second direction, orthogonal direction orthogonal to the first direction), the left side of the paper is the left side (one side of the second direction), and the right side of the paper is the right side (the other in the second direction). Side). The paper thickness direction is the depth direction (the direction orthogonal to the third direction, the first direction, and the second direction), and the front side of the paper surface is the front side (one side of the third direction), and the back side of the paper surface is the rear side. The side (the other side in the third direction). Specifically, it conforms to the direction arrows in each figure.

1. 1. Transparent conductive film The transparent conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a predetermined direction (plane direction) orthogonal to the thickness direction, and has a flat upper surface and a flat lower surface. .. The transparent conductive film 1 is, for example, a component for manufacturing a touch panel base material provided in an image display device, that is, it is not an image display device. That is, the transparent conductive film 1 is a device that does not include an image display element such as a liquid crystal cell, is distributed as a single component, and can be industrially used.

Specifically, as shown in FIG. 1, the transparent conductive film 1 includes a transparent base material 2, a first hard coat layer 3 arranged on the upper surface (one side) of the transparent base material 2, and a first hard. The first optical adjustment layer 4 arranged on the upper surface of the coat layer 3, the first transparent conductive layer 5 arranged on the upper surface of the first optical adjustment layer 4, and the lower surface (the other surface) of the transparent base material 2 are arranged. A second hard coat layer 6 is provided, a second optical adjustment layer 7 arranged on the lower surface of the second hard coat layer 6, and a second transparent conductive layer 8 arranged on the lower surface of the second optical adjustment layer 7. .. That is, in the transparent conductive film 1, the second transparent conductive layer 8, the second optical adjustment layer 7, the second hard coat layer 6, the transparent base material 2, the first hard coat layer 3, and the first optical adjustment are arranged in this order from the bottom. A layer 4 and a first transparent conductive layer 5 are provided.

The transparent conductive film 1 preferably includes a second transparent conductive layer 8, a second optical adjustment layer 7, a second hard coat layer 6, a transparent base material 2, a first hard coat layer 3, a first optical adjustment layer 4, and the like. It is composed of a first transparent conductive layer 5. Hereinafter, each layer will be described in detail.

(Transparent base material)
The transparent base material 2 is a base material that secures the mechanical strength of the transparent conductive film 1. In the transparent base material 2, the first transparent conductive layer 5 and the second transparent conductive layer 8 are combined with the first hard coat layer 3, the second hard coat layer 6, the first optical adjustment layer 4 and the second optical adjustment layer 7. I support it.

The transparent base material 2 is, for example, a transparent polymer film. Examples of the material of the polymer film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, and (meth) acrylic resins such as polymethacrylate (acrylic resin and / or methacrylic resin), for example. , Polyethylene, polypropylene, cycloolefin polymer (COP) and other olefin resins, such as polycarbonate resin, polyether sulfone resin, polyallylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, polystyrene resin, norbornene resin and the like. Be done. The polymer film can be used alone or in combination of two or more.

From the viewpoint of transparency, heat resistance, mechanical strength and the like, an olefin resin is preferably used, and COP is more preferable.

The thickness of the transparent base material 2 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 300 μm or less, from the viewpoints of mechanical strength, scratch resistance, and spotting characteristics of the touch panel film 1a. , 150 μm or less.

The thickness of the transparent base material 2 can be measured using, for example, a microgauge type thickness gauge.

If necessary, an easy-adhesion layer, an adhesive layer, or the like may be provided on the upper surface and / or the lower surface of the transparent base material 2.

(1st hard coat layer)
The first hard coat layer 3 is a scratch protection layer for making the transparent conductive film 1 less likely to be scratched.

The first hard coat layer 3 has a film shape, and is arranged, for example, on the entire upper surface of the transparent base material 2 so as to be in contact with the upper surface of the transparent base material 2. More specifically, the first hard coat layer 3 is in contact with the upper surface of the transparent base material 2 and the lower surface of the first optical adjustment layer 4 between the transparent base material 2 and the first optical adjustment layer 4. , Have been placed.

The first hard coat layer 3 is formed from, for example, a hard coat composition.

The hard coat composition of the first hard coat layer 3 contains a resin, and preferably comprises only the resin.

Examples of the resin include a curable resin and a thermoplastic resin (for example, a polyolefin resin), and a curable resin is preferable.

Examples of the curable resin include an active energy ray-curable resin that is cured by irradiation with active energy rays (specifically, ultraviolet rays, electron beams, etc.), for example, a thermosetting resin that is cured by heating. Preferably, an active energy ray-curable resin is used.

Examples of the active energy ray-curable resin include polymers having a functional group having a polymerizable carbon-carbon double bond in the molecule. Examples of such functional groups include vinyl groups, (meth) acryloyl groups (methacryloyl groups and / or acryloyl groups), and the like.

Specific examples of the active energy ray-curable resin include (meth) acrylic ultraviolet curable resins such as urethane acrylate and epoxy acrylate.

Examples of curable resins other than the active energy ray-curable resin include thermosetting resins such as urethane resin, melamine resin, alkyd resin, siloxane-based polymer, and organic silane condensate.

The resin can be used alone or in combination of two or more.

The hard coat composition can contain particles. As a result, the first hard coat layer 3 can be made into an anti-blocking layer having blocking resistance characteristics.

Examples of the particles include inorganic particles and organic particles. Examples of the inorganic particles include silica particles, for example, metal oxide particles composed of zirconium oxide, titanium oxide, zinc oxide, tin oxide and the like, and carbonate particles such as calcium carbonate. Examples of the organic particles include crosslinked acrylic resin particles. The particles can be used alone or in combination of two or more.

In addition, the hard coat composition can further contain known additives such as a leveling agent, a thixotropy agent, and an antistatic agent.

The refractive index of the first hard coat layer 3 is, for example, 1.40 or more, preferably 1.45 or more, and for example, less than 1.60, preferably 1.55 or less. By setting the first hard coat layer 3 in the above range, the refractive index of the first hard coat layer 3 can be made lower than the refractive index of the first optical adjustment layer 4, and the visibility of the electrode pattern is further suppressed. can do.

The refractive index of the hard coat layer (first hard coat layer 3 and second hard coat layer 6) can be measured using, for example, a spectroscopic ellipsometer.

The thickness of the first hard coat layer 3 is, for example, 0.1 μm or more, preferably 0.5 μm or more, and for example, 10 μm or less, preferably 10 μm or less, from the viewpoint of scratch resistance and suppression of visibility of the electrode pattern. It is 5 μm or less.

The thickness of the hard cord layer (first hard coat layer 3 and second hard coat layer 6) can be calculated based on the waveform of the interference spectrum using an instantaneous multi-photometric system (manufactured by Otsuka Electronics Co., Ltd., "MCPD2000"). it can.

(1st optical adjustment layer)
The first optical adjustment layer 4 is used to ensure excellent transparency of the transparent conductive film 1 while suppressing the visibility of the pattern (for example, the electrode pattern) when the first transparent conductive layer 5 is patterned. , A layer for adjusting the optical properties (for example, refractive electrode) of the transparent conductive film 1.

The first optical adjustment layer 4 has a film shape, and is arranged, for example, on the entire upper surface of the first hard coat layer 3 so as to be in contact with the upper surface of the first hard coat layer 3. More specifically, the first optical adjustment layer 4 is placed between the first hard coat layer 3 and the first transparent conductive layer 5 on the upper surface of the first hard coat layer 3 and the lower surface of the first transparent conductive layer 5. Arranged to touch.

The first optical adjustment layer 4 is formed from an optical adjustment composition.

The optical adjustment composition contains, for example, a resin. The optical adjustment composition preferably contains a resin and particles, and more preferably consists only of the resin and particles.

The resin is not particularly limited, and examples thereof include the same resin used in the hard coat composition. The resin can be used alone or in combination of two or more. A curable resin is preferable, and an active energy ray-curable resin is more preferable.

The content ratio of the resin is, for example, 10% by mass or more, preferably 25% by mass or more, and for example, 95% by mass or less, preferably 60% by mass or less, based on the optical adjustment composition.

As the particles, a suitable material can be selected according to the refractive index required by the first optical adjustment layer 4, and examples thereof include inorganic particles and organic particles. Examples of the inorganic particles include silica particles, for example, metal oxide particles composed of zirconium oxide, titanium oxide, zinc oxide, oxidation and the like, and carbonate particles such as calcium carbonate. Examples of the organic particles include crosslinked acrylic resin particles. The particles can be used alone or in combination of two or more.

The particles preferably include inorganic particles, more preferably metal oxide particles, and even more preferably zirconium oxide particles (ZnO ₂ ).

The average particle size (median diameter) of the particles is, for example, 10 nm or more, preferably 20 nm or more, and for example, 100 nm or less, preferably 50 nm or less.

The content ratio of the particles is, for example, 5% by mass or more, preferably 40% by mass or more, and for example, 90% by mass or less, preferably 75% by mass or less, based on the optical adjustment composition.

The refractive index of the first optical adjustment layer 4 is higher than the refractive index of the second optical adjustment layer 7, for example, 1.65 or more, preferably 1.70 or more. The upper limit is, for example, 1.80 or less, preferably 1.75 or less. When the refractive index of the first optical adjustment layer 4 is within the above range, the light transmittance of the transparent conductive film 1 can be further improved.

The refractive index of the optical adjustment layer (first optical adjustment layer 4 and second optical constituent layer 7) can be measured using, for example, a spectroscopic ellipsometer.

The thickness of the first optical adjustment layer 4 is, for example, 150 nm or less, preferably 100 nm or less, more preferably 85 nm or less, and for example, 10 nm or more, preferably 20 nm or more. When the thickness of the first optical adjustment layer 4 is not more than the above upper limit, the hue of the transparent conductive film 1 (particularly, ^{the color space of La *} b ^* ) can be more reliably neutralized. That is, the coloring (for example, yellow) of the transparent conductive film 1 can be reduced, and the colorless and transparent transparent conductive film 1 can be surely obtained.

The thickness of the optical adjustment layer (first optical adjustment layer 4 and second optical adjustment layer 7) is calculated based on the waveform of the interference spectrum using, for example, an instantaneous multi-photometric system (manufactured by Otsuka Electronics Co., Ltd., “MCPD2000”). be able to.

(First transparent conductive layer)
The first transparent conductive layer 5 is a transparent conductive layer for forming into a predetermined pattern (for example, an electrode pattern) in a post-process such as etching.

The first transparent conductive layer 5 is the uppermost layer of the transparent conductive film 1, has a film shape, and is in contact with the entire upper surface of the first optical adjustment layer 4 and the upper surface of the first optical adjustment layer 4. It is arranged so that.

As the material of the first transparent conductive layer 5, for example, at least selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. Examples include metal oxides containing one type of metal. The metal oxide may be further doped with the metal atoms shown in the above group, if necessary.

The material of the first transparent conductive layer 5 is preferably an indium-containing oxide such as an indium-tin composite oxide (ITO), for example, an antimon-containing oxide such as an antimon-tin composite oxide (ATO). , More preferably an indium-containing oxide, and even more preferably ITO. As a result, the first transparent conductive layer 5 can achieve both excellent transparency and conductivity.

When ITO is used as the material of the first transparent conductive layer 5, the tin oxide (SnO ₂ ) content is, for example, 0.5% by mass or more with respect to the total amount of tin oxide and indium oxide (In ₂ O _3). It is preferably 3% by mass or more, and for example, 15% by mass or less, preferably 13% by mass or less.

“ITO” may be a composite oxide containing at least indium (In) and tin (Sn), and may contain additional components other than these. Examples of the additional component include metal elements other than In and Sn, and specifically, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, W and Fe. , Pb, Ni, Nb, Cr, Ga and the like.

The first transparent conductive layer 5 may be either crystalline or amorphous. The first transparent conductive layer 5 is preferably made of crystalline material, and more specifically, it is a crystalline ITO layer. As a result, the transparency of the first transparent conductive layer 5 can be improved, and the surface resistance value of the first transparent conductive layer 5 can be further reduced.

The fact that the transparent conductive layer (first transparent conductive layer 5 and second transparent conductive layer 8) is crystalline means that, for example, when the transparent conductive layer is an ITO layer, hydrochloric acid (concentration: 5% by mass) at 20 ° C. It can be judged by immersing it for 15 minutes, washing it with water, drying it, and measuring the resistance between terminals within about 15 mm. Specifically, when the resistance between terminals for 15 mm is 10 kΩ or less after immersion in hydrochloric acid (20 ° C., concentration: 5% by mass), washing with water, and drying, the ITO layer is assumed to be crystalline.

The surface resistance value of the first transparent conductive layer 5 is lower than the surface resistance value of the second transparent conductive layer 8, and specifically, it is 10 Ω / □ or more and 70 Ω / □ or less. It is preferably 20 Ω / □ or more, more preferably 30 Ω / □ or more, and preferably 60 Ω / □ or less, more preferably 50 Ω / □ or less. When the surface resistance value of the first transparent conductive layer 5 is within the above range, the transparent conductive film 1 can exhibit excellent electromagnetic wave shielding properties and conductivity.

The surface resistance value of the transparent conductive layer (the first transparent conductive layer 5 and the second transparent conductive layer 8) can be measured by using, for example, the four-terminal method.

The thickness of the first transparent conductive layer 5 is preferably thicker than the thickness of the second transparent conductive layer 8, for example, 30 nm or more, preferably 35 nm or more, and for example, 200 nm or less, preferably 100 nm or less. , More preferably 60 nm or less. When the thickness of the first transparent conductive layer 5 is within the above range, the electromagnetic wave shielding property of the transparent conductive film 1 can be further improved.

The thickness of the transparent conductive layer (the first transparent conductive layer 5 and the second transparent conductive layer 8) can be measured, for example, by observing the cross section of the transparent conductive layer with a transmission electron microscope (TEM).

(2nd hard coat layer)
The second hard coat layer 6 is a scratch protection layer for making the transparent conductive film 1 less likely to be scratched.

The second hard coat layer 6 has a film shape, and is arranged, for example, on the entire lower surface of the transparent base material 2 so as to be in contact with the lower surface of the transparent base material 2. More specifically, the second hard coat layer 6 is in contact with the lower surface of the transparent base material 2 and the upper surface of the second optical adjustment layer 7 between the transparent base material 2 and the second optical adjustment layer 7. , Have been placed.

The second hard coat layer 6 is the same layer as the first hard coat layer 3, and has, for example, the same material (thickness, refractive index, etc.) as the first hard coat layer 3. Therefore, the second hard coat layer 6 also has the same shape and dimensions as the first hard coat layer 3.

(Second optical adjustment layer)
When the second transparent conductive layer 8 is patterned, the second optical adjusting layer 7 suppresses the visibility of the pattern (for example, the electrode pattern) and secures the excellent transparency of the transparent conductive film 1. , A layer for adjusting the optical properties (for example, refractive electrode) of the transparent conductive film 1.

The second optical adjustment layer 7 has a film shape, and is arranged, for example, on the entire lower surface of the second hard coat layer 6 so as to be in contact with the lower surface of the second hard coat layer 6. More specifically, the second optical adjustment layer 7 is placed between the second hard coat layer 6 and the second transparent conductive layer 8 with the lower surface of the second hard coat layer 6 and the upper surface of the second transparent conductive layer 8. Arranged to touch.

The second optical adjustment layer 7 is formed from the optical adjustment composition. Examples of the optical adjustment composition include those similar to those described above in the first optical adjustment layer 4.

The refractive index of the second optical adjustment layer 7 is lower than that of the first optical adjustment layer 4, for example, 1.70 or less, preferably less than 1.65, and more preferably 1.64 or less. is there. The lower limit is, for example, 1.55 or more, preferably 1.60 or more. When the refractive index of the second optical adjustment layer 7 is within the above range, the light transmittance of the transparent conductive film 1 can be further improved.

The difference in refractive index between the second optical adjustment layer 7 and the first optical adjustment layer 4 is, for example, 0.01 or more, preferably 0.05 or more, and for example, 0.20 or less, preferably 0.20 or less. It is 0.15 or less. When the difference in refractive index is within the above range, the transparency of the transparent conductive film 1 can be improved and the hue can be neutralized.

The thickness of the second optical adjustment layer 7 is, for example, 150 nm or less, preferably 100 nm or less, more preferably 85 nm or less, and for example, 10 nm or more, preferably 20 nm or more. When the thickness of the second optical adjustment layer 7 is not more than the above upper limit, the hue can be more reliably neutralized.

(Second transparent conductive layer)
The second transparent conductive layer 8 is a transparent conductive layer for forming into a predetermined pattern (for example, an electrode pattern) in a post-process such as etching.

The second transparent conductive layer 8 is the lowermost layer of the transparent conductive film 1, has a film shape, and has a film shape so that the entire lower surface of the second optical adjustment layer 7 is in contact with the lower surface of the second optical adjustment layer 7. Is placed in.

Examples of the material constituting the second transparent conductive layer 8 include the same materials as those described above for the first transparent conductive layer 5. It is preferably ITO. The second transparent conductive layer 8 may be either crystalline or amorphous, but is preferably crystalline, and more specifically, a crystalline ITO layer.

The surface resistance value of the second transparent conductive layer 8 is higher than the surface resistance value of the first transparent conductive layer 5, and specifically, it is 50 Ω / □ or more and 150 Ω / □ or less. It is preferably 60 Ω / □ or more, more preferably 70 Ω / □ or more, still more preferably 100 Ω / □ or more, and preferably 120 Ω / □ or less. When the surface resistance value of the second transparent conductive layer 8 is within the above range, the thickness of the second transparent conductive layer 8 can be reduced, and the light transmittance of the transparent conductive film 1 can be improved.

The difference in surface resistance between the first transparent conductive layer 5 and the second transparent conductive layer 8 is, for example, 10 Ω / □ or more, preferably 20 Ω / □ or more, more preferably 40 Ω / □ or more, and for example. , 100Ω / □ or less, preferably 70Ω / □ or less.

The thickness of the second transparent conductive layer 8 is preferably thinner than the thickness of the first transparent conductive layer 5, for example, 35 nm or less, preferably 30 nm or less, and for example, 1 nm or more, preferably 10 nm or more. Is. When the thickness of the second transparent conductive layer 8 is within the above range, the light transmittance of the transparent conductive film 1 can be further improved.

2. Method for Producing Transparent Conductive Film In order to produce a transparent conductive film 1, first, a transparent base material 2 is prepared, and then hard coat layers (first hard coat layer 3 and The second hard coat layer 6), the optical adjustment layer (the first optical adjustment layer 4 and the second optical adjustment layer 7), and the transparent conductive layer (the first transparent conductive layer 5 and the second transparent conductive layer 8) are provided in this order.

For example, first, a diluted solution in which the hard coat composition forming the first hard coat layer 3 or the second hard coat layer 6 is diluted with a solvent is prepared. Subsequently, the diluent is applied to the upper surface or the lower surface of the transparent substrate 2, each diluent is dried, and the hard coat composition is cured if necessary. As a result, the first hard coat layer 3 is provided on the upper surface of the transparent base material 2, and the second hard coat layer 6 is provided on the lower surface of the transparent base material 2.

Next, a diluted solution in which the optical adjustment composition forming the first optical adjustment layer 4 or the second optical adjustment layer 7 is diluted with a solvent is prepared. Subsequently, the diluent is applied to the upper surface of the first hard coat layer 3 or the lower surface of the second hard coat layer 6, the diluent is dried, and the optical adjustment composition is cured if necessary. As a result, the first optical adjustment layer 4 is provided on the upper surface of the first hard coat layer 3, and the second optical adjustment layer 7 is provided on the lower surface of the second hard coat layer 6. That is, a laminate of the second optical adjustment layer 7 / the second hard coat layer 6 / the transparent base material 2 / the first hard coat layer 3 / the first optical adjustment layer 4 is obtained.

Next, the first transparent conductive layer 5 and the second transparent conductive layer 8 are sequentially formed on both surfaces of the laminated body by a dry method.

Examples of the dry method include a vacuum deposition method, a sputtering method, an ion plating method and the like. Preferably, a sputtering method is used. By this method, a thin transparent conductive layer can be formed.

Examples of the sputtering method include a bipolar sputtering method, an ECR (electron cyclotron resonance) sputtering method, a magnetron sputtering method, and an ion beam sputtering method. Preferred is the magnetron sputtering method.

When the sputtering method is adopted, examples of the target material include the above-mentioned metal oxides constituting the transparent conductive layer, and preferably ITO. The tin oxide concentration of ITO is, for example, 0.5% by mass or more, preferably 3% by mass or more, and for example, 15% by mass or less, preferably 15% by mass, from the viewpoint of durability and crystallization of the ITO layer. , 13% by mass or less.

Examples of the gas include an inert gas such as Ar. Further, if necessary, a reactive gas such as oxygen gas can be used in combination. When the reactive gas is used in combination, the flow rate ratio (sccm) of the reactive gas is not particularly limited, but is, for example, 0.1 flow rate% or more and 5 flow rate% or less with respect to the total flow rate ratio of the sputter gas and the reactive gas. Is.

The atmospheric pressure during sputtering is, for example, 1 Pa or less, preferably 0.1 Pa or more and 0.7 Pa or less, from the viewpoint of suppressing a decrease in the sputtering rate and discharging stability.

The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source, or may be a combination thereof.

At this time, for example, the surface resistance value of each transparent conductive layer can be adjusted by separately adjusting the thicknesses of the first transparent conductive layer 5 and the second transparent conductive layer 8 provided on the laminated body. That is, the surface resistance value can be lowered by increasing the thickness of the transparent conductive layer, and conversely, the surface resistance value can be increased by reducing the thickness of the transparent conductive layer. In the present invention, the formation of each transparent conductive layer is preferably adjusted so that the thickness of the second transparent conductive layer 8 is thinner than the thickness of the first transparent conductive layer 5.

As a result, the second transparent conductive layer 8, the second optical adjustment layer 7, the second hard coat layer 6, the transparent base material 2, the first hard coat layer 3, the first optical adjustment layer 4, and the first transparent conductive layer 5 are formed. A transparent conductive film 1 provided in this order can be obtained.

If necessary, the transparent conductive film 1 is then heat-treated in the atmosphere.

The heat treatment can be carried out using, for example, an infrared heater, an oven, or the like.

The heating temperature is, for example, 100 ° C. or higher, preferably 120 ° C. or higher, and for example, 200 ° C. or lower, preferably 160 ° C. or lower.

The heating time is appropriately determined according to the heating temperature, but is, for example, 10 minutes or more, preferably 30 minutes or more, and for example, 5 hours or less, preferably 3 hours or less.

By this heat treatment, each transparent conductive layer can be crystallized and a desired surface resistance value can be obtained.

Further, in this manufacturing method, each layer can be provided on the transparent base material 2 by, for example, a roll-to-roll method, or a part or all of these layers are provided by a batch method (single leaf method). You can also do it.

The light transmittance (visual sensitivity average transmittance) of the transparent conductive film 1 is, for example, 86.0% or more, preferably 86.5% or more. When the light transmittance is in the above range, the transparent transparent conductive film 1 can be surely obtained.

The hue La * of the transparent conductive film 1 is, for example, -1.5 or more, preferably -1.0 or more, and for example, preferably 1.5 or less, preferably 0.5 or less. is there. The hue Lb * is, for example, -4.0 or more, preferably −0.5 or more, and for example, preferably 4.0 or less, preferably 1.0 or less. When the hue is in the above range, the colorless and transparent transparent conductive film 1 can be surely obtained.

The transparent conductive film 1 can be used as a touch panel film for, for example, an optical method, an ultrasonic method, a capacitance method, a resistance film method, or the like. In particular, it can be suitably used as a film for a touch panel of a capacitance type (specifically, a projection type capacitance type).

3. 3. Film for Touch Panel Next, the film 1a for a touch panel, which is an embodiment of the transparent conductive film 1, will be described.

As shown in FIG. 2, the touch panel film 1a has a transparent base material 2, a first hard coat layer 3 arranged on the upper surface of the transparent base material 2, and a first hard coat layer 3 arranged on the upper surface of the first hard coat layer 3. 1 Optical adjustment layer 4, patterning first transparent conductive layer 5a arranged on the upper surface of the first optical adjustment layer 4, second hard coat layer 6 arranged on the lower surface of the transparent base material 2, and second hard coat. A second optical adjustment layer 7 arranged on the lower surface of the layer 6 and a patterning second transparent conductive layer 8a arranged on the lower surface of the second optical adjustment layer 7 are provided. That is, in the transparent conductive film 1, the patterning second transparent conductive layer 8a, the second optical adjustment layer 7, the second hard coat layer 6, the transparent base material 2, the first hard coat layer 3, and the first optical are arranged in this order from the bottom. The adjusting layer 4 and the patterning first transparent conductive layer 5a are provided. The touch panel film 1a preferably includes a patterning second transparent conductive layer 8a, a second optical adjustment layer 7, a second hard coat layer 6, a transparent base material 2, a first hard coat layer 3, a first optical adjustment layer 4, and the like. It is composed of a patterning first transparent conductive layer 5a.

As shown in FIGS. 3A to 3B, the touch panel film 1a has a substantially rectangular shape in a plan view that is long in the left-right direction (one direction, long side direction) and short in the front-rear direction (other direction, short side direction).

The touch panel film 1a is a patterned transparent conductive film obtained by patterning the transparent conductive layers (first transparent conductive layer 5 and second transparent conductive layer 8) of the transparent conductive film 1 described above. .. Therefore, the second optical adjustment layer 7, the second hard coat layer 6, the transparent base material 2, the first hard coat layer 3 and the first optical adjustment layer 4 of the touch panel film 1a are each layer of the transparent conductive film 1 described above. Is similar to.

As shown in FIG. 3A, the patterning first transparent conductive layer 5a includes a first rectangular pattern 11 extending in the left-right direction as an example of the first pattern in a substantially central portion in a plan view. Specifically, the patterning first transparent conductive layer 5a includes a plurality of first rectangular patterns 11 arranged at intervals in the front-rear direction. Further, a wiring 12 for electrically connecting the first rectangular pattern 11 to an integrated circuit (not shown) is integrally connected to the right end of the first rectangular pattern 11.

As shown in FIG. 3B, the patterning second transparent conductive layer 8a has a second rectangular pattern 13 extending in the front-rear direction (orthogonal direction orthogonal to the left-right direction) as an example of the second pattern in the substantially central portion of the bottom surface. It has. Specifically, the patterning second transparent conductive layer 8a includes a plurality of second rectangular patterns 13 arranged at intervals in the left-right direction. Further, a wiring 12 for electrically connecting the second rectangular pattern 13 to an integrated circuit (not shown) is integrally connected to the front end or the rear end.

The first rectangular pattern 11 of the patterning first transparent conductive layer 5a and the second rectangular pattern 13 of the patterning second transparent conductive layer 8a are orthogonal to each other when projected in the thickness direction (vertical direction). Have been placed.

The lateral length (long side length) of the first rectangular pattern 11 of the patterning first transparent conductive layer 5a is the anteroposterior length (long side length) of the second rectangular pattern 13 of the patterning second transparent conductive layer 8a. Is longer than that. As a result, the surface resistance value of the patterning first transparent conductive layer 5a having a long current traveling distance can be reduced, so that the current transmission speed of the patterning first transparent conductive layer 5a can be improved and noise can be reduced. Can be done. As a result, the size of the image display device 20 can be increased.

The patterning method is carried out, for example, by covering each transparent conductive layer with a mask for forming an electrode pattern and etching each transparent conductive layer with an etching solution. Acid is preferably used as the etching solution. Examples of the acid include inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid and phosphoric acid, organic acids such as acetic acid, mixtures thereof, and aqueous solutions thereof.

4. Action Effect This transparent conductive film 1 includes a first transparent conductive layer 5, a first optical adjusting layer 4, a transparent base material 2, a second optical adjusting layer 7, and a second transparent conductive layer 8 in this order, and thus is first transparent. When the conductive layer 5 and the second transparent conductive layer 8 are patterned, the visual recognition of the patterned first transparent conductive layer 5a and the patterned second transparent conductive layer 8a (for example, the electrode pattern) can be suppressed.

Further, since the surface resistance value of the first transparent conductive layer 5 is 10 Ω / □ or more and 70 Ω / □ or less, the transparent conductive film 1 includes the first transparent conductive layer 5 having a small surface resistance value on one side. Therefore, the transparent conductive film 1 can exhibit relatively good electromagnetic wave shielding property as compared with the transparent conductive film provided with the transparent conductive layer having a high surface resistance value on both sides.

Further, since the surface resistance value of the second transparent conductive layer 8 is larger than the surface resistance value of the first transparent conductive layer 5 and is 50 Ω / □ or more and 150 Ω / □ or less, the second transparent conductive layer 8 is used. 1 It can be made thinner than the transparent conductive layer 5. Further, the refractive index of the second optical adjustment layer 7 is lower than the refractive index of the first optical adjustment layer 4. The light transmittance of the transparent conductive film 1 can be improved by these surface resistance values and the refractive index.

Further, in the touch panel film 1a in which each transparent conductive layer of the transparent conductive film 1 is patterned together, the patterning first transparent conductive layer 5a includes a first rectangular pattern 11 that is long in the left-right direction, and the patterning second. The transparent conductive layer 8a includes a second rectangular pattern 13 that is long in the front-rear direction. Further, the length of the first rectangular pattern 11 in the left-right direction is longer than the length of the second pattern in the front-rear direction. Therefore, the surface resistance value of the patterning first transparent conductive layer 5a having a long current traveling distance can be reduced, so that the current transmission speed of the patterning first transparent conductive layer 5a can be improved and noise can be reduced. it can. As a result, the current speed of the transparent conductive film 1 as a whole can be improved and noise can be reduced, so that the size of the image display device 20 can be increased.

<Image display device>
Next, an embodiment of the image display device 20 will be described. As shown in FIG. 4, one embodiment of the image display device 20 includes a transparent protective plate 21, a first transparent adhesive layer 22, a touch panel film 1a, a second transparent adhesive layer 23, and an image display element. 24 and 24 are provided in order. In FIG. 4, the upper side is the element side and the lower side is the visual recognition side.

The transparent protective plate 21 is a layer for protecting the internal members of the image display device 20 such as the image display element 24 against impact and dirt from the outside.

Examples of the transparent protective plate 21 include a resin plate made of a hard resin such as an acrylic resin and a polycarbonate resin, for example, a glass plate and the like.

The thickness of the transparent protective plate 21 is, for example, 10 μm or more, preferably 500 μm or more, and for example, 10 mm or less, more preferably 5 mm or less.

The first transparent adhesive layer 22 is a layer for adhering the transparent protective plate 21 and the touch panel film 1a. The first transparent adhesive layer 22 has a film shape and is arranged on the transparent protective plate 21. More specifically, the first transparent adhesive layer 22 is formed between the transparent protective plate 21 and the touch panel film 1a with the upper surface of the transparent protective plate 21 and the lower surface of the touch panel film 1a (patterning second transparent conductive 8a). Arranged to touch.

The first transparent pressure-sensitive adhesive layer 22 is formed of a transparent pressure-sensitive adhesive composition. The composition of the adhesive composition is not limited, but for example, acrylic adhesive, rubber adhesive (butyl rubber, etc.), silicone adhesive, polyester adhesive, polyurethane adhesive, polyamide adhesive, epoxy adhesive. Examples thereof include agents, vinyl alkyl ether adhesives, and fluororesin adhesives.

The thickness of the first transparent adhesive layer 22 (distance from the upper surface of the transparent protective plate 21 to the lower surface of the patterned second transparent conductive 8a) is, for example, 1 μm or more, preferably 5 μm or more, and for example, 300 μm or less. It is preferably 150 μm or less, more preferably 50 μm or less.

The touch panel film 1a is arranged on the first transparent adhesive layer 22 so that the patterning first transparent conductive layer 5a is located on the upper side and the patterning second transparent conductive layer 8a is located on the lower side. More specifically, in the touch panel film 1a, the patterning second transparent conductive layer 8a comes into contact with the first transparent adhesive layer 22 between the first transparent adhesive layer 22 and the second transparent adhesive layer 23. The patterning first transparent conductive layer 5a is arranged so as to come into contact with the second transparent pressure-sensitive adhesive layer 23.

Further, on the upper surface of the touch panel film 1a, the upper surface and the side surface of the first rectangular pattern 11 of the patterning first transparent conductive layer 5a and the upper surface of the first optical adjustment layer 4 exposed from the patterning first transparent conductive layer 5a are , Is in contact with the first transparent pressure-sensitive adhesive layer 22. On the lower surface of the touch panel film 1a, the lower surface and the side surface of the second rectangular pattern 13 of the patterning transparent conductive layer 28a and the upper surface of the second optical adjustment layer 7 exposed from the patterning second transparent conductive layer 8a are second. It is in contact with the transparent pressure-sensitive adhesive layer 23.

The second transparent adhesive layer 23 is a layer for adhering the image display element 24 and the touch panel film 1a. The second transparent adhesive layer 23 has a film shape and is arranged on the touch panel film 1a. More specifically, the second transparent adhesive layer 23 is arranged between the touch panel film 1a and the image display element 24 so as to be in contact with the upper surface of the touch panel film 1a and the lower surface of the image display element 24. There is.

The second transparent pressure-sensitive adhesive layer 23 is formed of the same pressure-sensitive adhesive composition as the first transparent pressure-sensitive adhesive layer 22. The thickness of the second transparent pressure-sensitive adhesive layer 23 is the same as the thickness of the first transparent pressure-sensitive adhesive layer 22.

The image display element 24 is arranged on the second transparent adhesive layer 23. More specifically, in the image display element 24, the second transparent adhesive layer 23 is provided so that the image display surface 25 is on the lower side and the image display surface 25 is in contact with the upper surface of the second transparent adhesive layer 23. It is placed on the upper surface of.

Examples of the image display element 24 include a liquid crystal cell and an organic EL.

Since the image display device 20 includes the touch panel film 1a, it has an electromagnetic wave shielding effect, and good light while suppressing the visibility of the patterning first transparent conductive layer 5a and the patterning second transparent conductive layer 8a (electrode pattern). It has transparency. Therefore, it is possible to increase the screen size.

Further, in the image display device 20, the image display element 24 is arranged on the patterning first transparent conductive layer 5a side (upper side). Therefore, the distance between the patterning first transparent conductive layer 5a (first transparent conductive layer 5), which has a strong electromagnetic wave shielding effect, and the image display element 24 that generates electromagnetic waves is shortened. Therefore, the electromagnetic waves of the image display element 24 can be absorbed more reliably, and the electromagnetic wave shielding effect of the image display device 20 is excellent.

<Modification example>
(1) In the embodiment shown in FIG. 1, the transparent conductive film 1 is, in order from the bottom, a second transparent conductive layer 8, a second optical adjustment layer 7, a second hard coat layer 6, a transparent base material 2, and a first. The hard coat layer 3, the first optical adjustment layer 4, and the first transparent conductive layer 5 are provided. For example, although not shown, the second hard coat layer 6 and the first hard coat layer 3 may not be provided. That is, the transparent conductive film 1 is composed of a second transparent conductive layer 8, a second optical adjusting layer 7, a transparent base material 2, a first optical adjusting layer 4, and a first transparent conductive layer 5 in this order from the bottom.

Preferably, from the viewpoint of scratch resistance, the embodiment shown in FIG. 1 can be mentioned. The same applies to the touch panel film 1a and the image display device 20.

(2) In the embodiment shown in FIGS. 3A to 3B, the patterning first transparent conductive layer 5a includes a first rectangular pattern 11 that is long in the left-right direction, and the patterning second transparent conductive layer 8a is a second that is long in the front-rear direction. The rectangular pattern 13 is provided, but for example, although not shown, the patterning second transparent conductive layer 8a includes a first rectangular pattern 11 that is long in the left-right direction, and the patterning first transparent conductive layer 5a is provided in the front-rear direction. A long second rectangular pattern 13 can also be provided.

In this embodiment, the length of the first rectangular pattern 11 of the patterning second transparent conductive layer 8a in the left-right direction is longer than the length of the second rectangular pattern 13 of the patterning first transparent conductive layer 5a in the front-rear direction.

Preferably, the embodiments shown in FIGS. 3A to 3B can be mentioned from the viewpoint that the current velocity and noise of the transparent conductive layer having a long electrode pattern length can be improved.

(3) In the embodiments shown in FIGS. 3A to 3B, the first rectangular pattern 11 extending in the left-right direction is used as an example of the first pattern, and the second rectangular pattern 13 extending in the front-back direction is used as an example of the second pattern. For example, as shown in FIGS. 5A to 5B, as an example of the first pattern, a first continuous rectangular pattern 14 in which a plurality of rectangular patterns are continuous in the left-right direction is used, and as an example of the second pattern, a plurality of rectangular patterns are arranged in the front-rear direction. It can also be a continuous second continuous rectangular pattern 15.

That is, in the embodiment shown in FIGS. 5A to 5B, the patterning first transparent conductive layer 5a includes a plurality of first continuous rectangular patterns 14 arranged at intervals in the left-right direction. In the first continuous rectangular pattern 14, a plurality of substantially rectangular patterns are arranged in a straight line so that their diagonal lines are along the left-right direction.

The patterning second transparent conductive layer 8a includes a plurality of second continuous rectangular patterns 15 arranged at intervals in the front-rear direction. In the second continuous rectangular pattern 15, a plurality of substantially rectangular patterns are arranged in a straight line so that their diagonal lines are along the front-rear direction.

The first continuous rectangular pattern 14 of the patterning first transparent conductive layer 5a and the second continuous rectangular pattern 15 of the patterning second transparent conductive layer 8a are arranged so as to be orthogonal to each other when projected in the thickness direction. ing. Further, when projected in the thickness direction, the first continuous rectangular pattern is prevented so that the rectangular pattern constituting the first continuous rectangular pattern 14 does not overlap with the rectangular pattern constituting the second continuous rectangular pattern 15. 14 and the second continuous rectangular pattern 15 are arranged. Further, when projected in the thickness direction, the first continuous rectangle is such that the combined pattern of the first continuous rectangular pattern 14 and the second continuous rectangular pattern 15 covers the entire substantially central portion of the touch panel film 1a. The shape pattern 14 and the second continuous rectangular pattern 15 are arranged.

(4) In the image display device 20 shown in FIG. 4, the touch panel film 1a and the image display element 24 are arranged so that the image display element 24 is located on the patterning first transparent conductive layer 5a side. Although not shown, the touch panel film 1a and the image display element 24 may be arranged so that the image display element 24 is located on the patterning second transparent conductive layer 8a side. That is, in the image display device 20, the transparent protective plate 21, the first transparent adhesive layer 22, and the touch panel are arranged so that the patterning first transparent conductive layer 5a is on the lower side and the patterning second transparent conductive layer 8a is on the upper side. The film 1a, the second transparent adhesive layer 23, and the image display element 24 can be provided in this order from the bottom.

Preferably, the embodiment shown in FIG. 4 is mentioned from the viewpoint of the electromagnetic wave shielding effect of the image display device 20 as a whole.

Examples and comparative examples are shown below, and the present invention will be described in more detail. The present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, and parameters used in the following description are the compounding ratios corresponding to those described in the above-mentioned "Form for carrying out the invention" (forms for carrying out the invention). Substitute the upper limit value (value defined as "less than or equal to" or "less than") or the lower limit value (value defined as "greater than or equal to" or "excess") such as content ratio), physical property value, and parameters. be able to.

(Example 1)
Hard coat composition (acrylic UV curable resin, manufactured by DIC, "Unidic RS29-") on both sides of a transparent base material (COP film, manufactured by Nippon Zeon, trade name "Zeonoa ZF-16", thickness 100 μm) The diluted solution of 120 ") was applied using a gravure coater and dried by heating at 80 ° C. for 1 minute. Then, ultraviolet rays were irradiated using a high-pressure mercury lamp to form first and second hard coat layers (each thickness 1.0 μm, each refractive index 1.53). As a result, a laminate of the first hard coat layer, the transparent base material and the second hard coat layer was obtained.

Next, a diluted solution of the optical adjustment composition having a refractive index of 1.70 was applied to the surface of the first hard coat layer of the laminate using a gravure coater, and dried by heating at 60 ° C. for 1 minute. Then, the first optical adjustment layer (refractive index 1.70, thickness 80 nm) was formed by irradiating ultraviolet rays with a high-pressure mercury lamp. Further, a second optical adjustment layer (refractive index 1.64, thickness 80 nm) was formed on the surface of the second hard coat layer in the same manner as above except that the optical adjustment composition having a refractive index of 1.64 was used. Formed. As a result, a laminate of the first optical adjustment layer, the first hard coat layer, the transparent base material, the second hard coat layer, and the first optical adjustment layer was obtained.

Each optical adjusting composition includes a refractive index adjusting agent having a refractive index of 1.60 (manufactured by JSR, "Opstar") and a refractive index adjusting agent having a refractive index of 1.74 (manufactured by JSR, "Opstar KZ6734"). Was prepared by appropriately mixing with.

Next, the obtained laminate was put into a sputtering apparatus, and an indium tin oxide layer (ITO layer) was laminated on both sides of the laminate. As the gas, a mixed gas composed of 98% argon gas and 2% oxygen was used, and the pressure of the atmosphere was set to 0.4 Pa. Further, as a target for sputtering, a sintered body composed of 90% by mass of indium oxide and 10% by mass of tin oxide was used. Further, the thickness of the first transparent conductive layer laminated on the first optical adjustment layer side was adjusted to 40 nm, and the thickness of the second transparent conductive layer laminated on the second optical adjustment layer side was adjusted to 30 nm.

As a result, a transparent conductive film composed of a first transparent conductive layer, a first optical adjustment layer, a first hard coat layer, a transparent base material and a second hard coat layer, a first optical adjustment layer and a second transparent conductive layer is obtained. It was.

Next, the transparent conductive film was heated in an oven at 140 ° C. for 90 minutes to crystallize the first and second transparent conductive layers to produce the double-sided transparent conductive film of Example 1.

(Examples 2 to 9 and Comparative Examples 1 to 5)
The thickness and refractive index of the optical adjustment layer and the thickness and surface resistance value of the transparent conductive layer were changed to the thickness and refractive index of the optical adjustment layer and the thickness and surface resistance value of the transparent conductive layer shown in Table 1. A transparent conductive film was produced in the same manner as in Example 1 except for the above.

(Comparative Example 6)
A transparent conductive film was produced in the same manner as in Example 1 except that the first optical adjustment layer and the second optical adjustment layer were not provided.

The following measurements were carried out for the transparent conductive films of each example and each comparative example, and the results are shown in Table 1.

<Surface resistance>
Using the 4-terminal method, the surface resistance (Ω / □) of each transparent conductive layer of the transparent conductive film of each Example and each Comparative Example was measured.

<Layer thickness>
The thickness of each hard coat layer and each optical adjustment layer was calculated based on the waveform from the interference spectrum using an instantaneous multi-photometric system (manufactured by Otsuka Electronics Co., Ltd., "MCPD2000").

The thickness of each transparent conductive layer was measured by observing a cross-sectional view of the transparent conductive film cut with a transmission electron microscope (TEM).

<Refractive index>
Only the hard coat layer to be measured is formed on a transparent film (COP film, manufactured by Nippon Zeon Co., Ltd., "Zeonoa ZF-16"), and a spectroscopic ellipsometer (manufactured by JA Woolam Co., Ltd., model number FQTH-100) is formed. The refractive index was measured using.

Further, only the optical adjustment layer to be measured was formed on a transparent film (same as above), and the refractive index was measured using a spectroscopic ellipsometer (same as above).

When the adhesion between the transparent film and the hard coat layer or the optical adjustment layer was poor, surface modification such as corona treatment was appropriately performed.

<Transmittance, hue>
A transparent film (manufactured by Nitto Denko, model number No. 7, thickness 25 μm) is interposed on both sides of the transparent conductive film of each example and each comparative example, and a transparent film (manufactured by Nippon Zeon, "Zeonoa ZF-"). 14 ”, thickness 100 μm) were bonded together. As a result, a sample for measuring the transmittance (transparent film / adhesive / transparent conductive film / adhesive / transparent film) was obtained. Using a spectrophotometer (manufactured by Murakami Color Co., Ltd., model number "Dot-3"), this sample was used to measure the average luminous efficiency and hues a * and b * at wavelengths of 380 to 700 nm. The results are shown in Table 1.

<Visibility of electrode pattern>
In the transparent conductive films of each example and each comparative example, the first transparent conductive layer and the second transparent conductive layer were etched with an etching solution and patterned into the electrode patterns of FIGS. 3A to 3B. The patterned transparent conductive film was visually recognized from diagonally above. The case where the electrode pattern was clearly visible was evaluated as x, and the case where the electrode pattern was hardly visually recognized was evaluated as ◯. The results are shown in Table 1.

1 Transparent conductive film 2 Transparent substrate 4 First optical adjustment layer 5 First transparent conductive layer 7 Second optical adjustment layer 8 Second transparent conductive layer 11 First rectangular pattern 13 Second rectangular pattern 20 Image display device 24 Image display element

Claims (6)

A first transparent conductive layer, a first optical adjusting layer, a transparent base material, a second optical adjusting layer, and a second transparent conductive layer are provided in this order.
The surface resistance value of the second transparent conductive layer is larger than the surface resistance value of the first transparent conductive layer.
The surface resistance value of the first transparent conductive layer is 10 Ω / □ or more and 70 Ω / □ or less.
The surface resistance value of the second transparent conductive layer is 50 Ω / □ or more and 150 Ω / □ or less.
A transparent conductive film characterized in that the refractive index of the second optical adjustment layer is lower than the refractive index of the first optical adjustment layer. The transparent conductive film according to claim 1, wherein the thickness of the second transparent conductive layer is thinner than the thickness of the first transparent conductive layer. The refractive index of the first optical adjustment layer is 1.65 or more and 1.75 or less.
The transparent conductive film according to claim 1 or 2, wherein the refractive index of the second optical adjustment layer is 1.60 or more and 1.70 or less. The transparent conductive film according to any one of claims 1 to 3, wherein the thickness of the first optical adjustment layer and the thickness of the second optical adjustment layer are both 100 nm or less. The first transparent conductive layer and the second transparent conductive layer are both patterned.
The first transparent conductive layer has a first pattern that is long in one direction.
The second transparent conductive layer has a second pattern that is long in the orthogonal direction orthogonal to the one direction.
The transparent conductive film according to any one of claims 1 to 4, wherein the unidirectional length of the first pattern is longer than the orthogonal length of the second pattern. The transparent conductive film according to any one of claims 1 to 5.
An image display device including an image display element arranged on the first transparent conductive layer side of the transparent conductive film.

Images