JP7287802B2 - light transmissive conductive film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a light-transmitting conductive film, and more particularly to a light-transmitting conductive film suitable for optical applications.

BACKGROUND ART Conventionally, a transparent conductive film having a transparent conductive layer is used as a substrate for a touch panel in an image display device. For example, Patent Literature 1 discloses a transparent conductive film including a polymer film and a transparent conductive layer made of indium-tin composite oxide (ITO).

In such a transparent conductive film, generally, amorphous ITO is crystallized by heating to improve conductivity (low resistance) of the transparent conductive layer.

JP 2012-134085 A

However, in the transparent conductive film of Patent Document 1, the crystallization rate of the transparent conductive layer is insufficient, and further improvement in the rate is required. That is, it is demanded to crystallize the transparent conductive film in a short time.

On the other hand, if the crystallization rate during heating is improved, crystallization becomes easier even under low temperature conditions such as room temperature. That is, before crystallization (before product shipment), the product is unintentionally crystallized during temporary storage, for example, in a warehouse. In this case, since the transparent conductive layer is partially crystallized, strain occurs at the boundary between the crystallized portion generated during storage and the amorphous portion in the subsequent crystallization process during heating, and cracks occur. A problem occurs. That is, it is inferior in preservability.

An object of the present invention is to provide a light-transmitting conductive film having a good crystallization rate when heated and a good storage stability.

The present invention [1] comprises a transparent substrate and an amorphous light-transmitting conductive layer disposed on one side in the thickness direction of the transparent substrate, wherein the amorphous light-transmitting conductive layer is a crystalline The thickness of the amorphous light-transmitting conductive layer exceeds 40 nm, and the carrier density in the amorphous light-transmitting conductive layer is 40×10 ¹⁹ /cm ³ or more. , including a light-transmissive conductive film.

The present invention [2] includes the light-transmitting conductive film according to [1], wherein the amorphous light-transmitting conductive layer contains an indium-based inorganic oxide.

The present invention [3] is described in [1] or [2], wherein the amorphous light-transmitting conductive layer is an indium-based inorganic oxide layer containing indium and one or more impure inorganic elements. including a light-transmissive conductive film.

According to the light-transmitting conductive film of the present invention, the crystallization speed during heating and the storage stability are good. Therefore, even after the light-transmitting conductive film of the present invention is stored for a certain period of time, the light-transmitting conductive film can be crystallized in a short time while suppressing the occurrence of cracks.

FIG. 1 shows a cross-sectional view of one embodiment of the light-transmitting conductive film of the present invention. FIG. 2 shows a cross-sectional view of a crystalline light-transmitting conductive film obtained by crystallizing the light-transmitting conductive film shown in FIG.

<One embodiment>
One embodiment of the light-transmissive conductive film 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG.

In FIG. 1, the vertical direction of the paper is the vertical direction (thickness direction, first direction), the upper side of the paper is the upper side (one side in the thickness direction, the one side of the first direction), and the lower side of the paper is the lower side (thickness direction). the other side, the other side in the first direction). Moreover, the left-right direction and the depth direction on the paper surface are plane directions orthogonal to the up-down direction. Specifically, it conforms to the directional arrows in each figure.

1. Light-transmitting conductive film The light-transmitting conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a predetermined direction (surface direction) perpendicular to the thickness direction, and has a flat upper surface and a flat surface. It has a lower surface. The light-transmissive conductive film 1 is, for example, a component such as a base material for a touch panel provided in an image display device, that is, it is not an image display device. That is, the light-transmissive conductive film 1 is a component for producing an image display device or the like, does not include an image display element such as an LCD module, and includes a transparent substrate 2, a hard coat layer 3, and an optical adjustment layer 4, which will be described later. , and an amorphous light-transmitting conductive layer 5, and is a device that can be distributed as a single component and can be used industrially.

Specifically, as shown in FIG. 1, the light-transmissive conductive film 1 includes a transparent substrate 2, a hard coat layer 3 disposed on the upper surface (one surface in the thickness direction) of the transparent substrate 2, and a hard coat It comprises an optical adjustment layer 4 arranged on top of the layer 3 and an amorphous light-transmitting conductive layer 5 arranged on top of the optical adjustment layer 4 . More specifically, the light-transmitting conductive film 1 includes a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4, and an amorphous light-transmitting conductive layer 5 in this order. The light-transmitting conductive film 1 preferably comprises a transparent substrate 2 , a hard coat layer 3 , an optical adjustment layer 4 and an amorphous light-transmitting conductive layer 5 . Moreover, the light transmissive conductive film 1 is a transparent conductive film.

2. Transparent Base Material The transparent base material 2 is a transparent base material for ensuring the mechanical strength of the light-transmissive conductive film 1 . That is, the transparent substrate 2 supports the amorphous light-transmitting conductive layer 5 together with the hard coat layer 3 and the optical adjustment layer 4 .

The transparent substrate 2 is the bottom layer of the light-transmissive conductive film 1 and has a film shape. The transparent base material 2 is arranged on the entire bottom surface of the hard coat layer 3 so as to be in contact with the bottom surface of the hard coat layer 3 .

Examples of the transparent base material 2 include polymer films and inorganic plates (glass plates, etc.), and from the viewpoint of having both transparency and flexibility, polymer films are preferred.

Materials for the polymer film include, for example, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; , polyethylene, polypropylene, and cycloolefin polymers, such as polycarbonate resins, polyethersulfone resins, polyarylate resins, melamine resins, polyamide resins, polyimide resins, cellulose resins, and polystyrene resins. These polymer films can be used alone or in combination of two or more.

The transparent substrate 2 preferably includes a polyethylene terephthalate film and a cycloolefin polymer film from the viewpoint of transparency, flexibility, mechanical strength, and the like.

The total light transmittance (JIS K 7375-2008) of the transparent substrate 2 is, for example, 80% or more, preferably 85% or more.

The thickness of the transparent base material 2 is, for example, 2 μm or more, preferably 20 μm or more, from the viewpoint of mechanical strength, spotting characteristics when the light-transmitting conductive film 1 is used as a touch panel film, and the like. 300 μm or less, preferably 150 μm or less. The thickness of the transparent substrate 2 can be measured using, for example, a microgauge thickness meter.

A separator or the like may be provided on the lower surface of the transparent base material 2 .

3. Hard Coat Layer The hard coat layer 3 is a protective layer for preventing the transparent substrate 2 from being scratched when the light-transmissive conductive film 1 is produced. It is also a scratch-resistant layer for suppressing the generation of scratches on the amorphous light-transmitting conductive layer 5 when a plurality of light-transmitting conductive films 1 are laminated.

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

The hard coat layer 3 is formed from a hard coat composition. The hard coat composition contains a resin, and preferably consists of a resin.

Examples of resins include curable resins and thermoplastic resins (eg, polyolefin resins), and preferably curable resins.

Examples of curable resins include active energy ray-curable resins that are cured by irradiation with active energy rays (specifically, ultraviolet rays, electron beams, etc.), and thermosetting resins that are cured by heating. Active energy ray-curable resins are preferred.

Active energy ray-curable resins include, for example, polymers having functional groups having polymerizable carbon-carbon double bonds 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 active energy ray-curable resins include (meth)acrylic UV-curable resins such as urethane acrylate and epoxy acrylate.

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

These resins can be used singly or in combination of two or more.

The hardcoat composition can also contain particles. Thereby, the hard coat layer 3 can be made into an anti-blocking layer having anti-blocking properties.

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

The hard coat composition may further contain known additives such as leveling agents, thixotropic agents and antistatic agents.

From the viewpoint of scratch resistance, the thickness of the hard coat layer 3 is, for example, 0.1 μm or more, preferably 0.5 μm or more, and is, for example, 10 μm or less, preferably 3 μm or less. The thickness of the hard coat layer 3 can be measured by cross-sectional observation using, for example, a transmission electron microscope.

4. Optical Adjustment Layer The optical adjustment layer 4 suppresses the visibility of the pattern of the amorphous light-transmissive conductive layer 5 and ensures excellent transparency of the light-transmissive conductive film 1. It is a layer that adjusts the optical properties (for example, refractive index) of

The optical adjustment layer 4 has a film shape. The optical adjustment layer 4 is arranged on the entire upper surface of the hard coat layer 3 so as to be in contact with the upper surface of the hard coat layer 3 . More specifically, the optical adjustment layer 4 is formed between the hard coat layer 3 and the amorphous light-transmitting conductive layer 5 and on the top surface of the hard coat layer 3 and the bottom surface of the amorphous light-transmitting conductive layer 5 . arranged to make contact.

The optical adjustment layer 4 is formed from an optical adjustment composition. The optical adjustment composition contains a resin, preferably a resin and particles.

The resin is not particularly limited, but includes, for example, the resins exemplified for the hard coat composition. A curable resin is preferred, an active energy ray curable resin is more preferred, and a (meth)acrylic UV curable resin is even more preferred.

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

As the particles, a suitable material can be selected according to the refractive index required for the optical adjustment layer, and examples thereof include the particles exemplified for the hard coat composition. From the viewpoint of refractive index, inorganic particles are preferred, metal oxide particles are more preferred, and zirconium oxide particles (ZrO ₂ ) are even more preferred.

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

The optical adjustment composition may further contain known additives such as leveling agents, thixotropic agents and antistatic agents.

The refractive index of the optical adjustment layer 4 is, for example, 1.40 or more, preferably 1.55 or more, and for example, 1.80 or less, preferably 1.70 or less. The refractive index can be measured, for example, with an Abbe refractometer.

The thickness of the optical adjustment layer 4 is, for example, 5 nm or more, preferably 10 nm or more, and is, for example, 200 nm or less, preferably 100 nm or less. The thickness of the optical adjustment layer 4 can be measured by cross-sectional observation using, for example, a transmission electron microscope.

5. Light-Transmitting Conductive Layer The amorphous light-transmitting conductive layer 5 is a transparent conductive layer for forming a desired pattern (for example, an electrode pattern or a wiring pattern) by etching.

The amorphous light-transmissive conductive layer 5 is the uppermost layer of the light-transmissive conductive film 1 and has a film shape. The amorphous light-transmissive conductive layer 5 is arranged on the entire upper surface of the optical adjustment layer 4 so as to be in contact with the upper surface of the optical adjustment layer 4 .

Examples of materials for the amorphous light-transmitting conductive layer 5 include indium-based inorganic oxides and antimony-based inorganic oxides, and preferably indium-based inorganic oxides.

Sn, Zn, Ga, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, W, Fe, Pb, Ni, Nb, etc. , and Cr. Sn is preferably used as the impure inorganic element.

Examples of inorganic oxides containing impure inorganic elements include indium tin composite oxides (ITO) in the case of indium-based inorganic oxides, and antimony tin composite oxides in the case of antimony inorganic oxides. (ATO). ITO is preferred.

When the amorphous light-transmitting conductive layer 5 is made of ITO, the tin oxide (SnO ₂ ) content in the entire amorphous light-transmitting conductive layer 5 is equal to that of tin oxide and indium oxide (In ₂ O ₃ ), for example, 0.5% by mass or more, preferably 3% by mass or more, and for example, 15% by mass or less, preferably 13% by mass or less.

The amorphous light-transmitting conductive layer 5 may be composed of a single layer, or may be composed of a plurality of layers (regions in the thickness direction). The number of layers is not limited, and includes, for example, 2 to 5 layers, preferably 2 layers.

When the amorphous light-transmitting conductive layer 5 is composed of a plurality of layers, preferably the amorphous light-transmitting conductive layer 5 is the first layer (the first layer), as indicated by the phantom lines in FIG. 1 region) 5a, and a second layer (second region) 5b arranged on the upper side of the first layer 5a.

The first layer 5a and the second layer 5b are both preferably formed from inorganic oxides containing impure inorganic elements, and preferably both are formed from indium-based inorganic oxides containing impure inorganic elements. and more preferably both are made of ITO.

In this case, the mass ratio of the impure inorganic element (preferably Sn) to indium in the layer farthest from the transparent substrate 2 (that is, the second layer 5b) is It is preferably not the largest but more preferably the smallest among the constituent layers (that is, the first layer 5a and the second layer 5b). That is, when the amorphous light-transmissive conductive layer 5 is composed of the first layer 5a and the second layer 5b, the mass ratio of the impure inorganic element to indium in the second layer 5b is smaller than the mass ratio of the element.

Specifically, the mass ratio of the impure inorganic element to indium in the first layer 5a is preferably 0.05 or more, and the mass ratio of the impure inorganic element to indium in the second layer 5b is preferably 0.05. less than 05. This makes it possible to crystallize the amorphous light-transmissive conductive layer 5 more reliably in a short period of time.

More specifically, when the first layer 5a is made of ITO, the tin oxide (SnO ₂ ) content in the first layer 5a is the total amount of tin oxide and indium oxide (In ₂ O ₃ ). , for example, 5% by mass or more, preferably 8% by mass or more, and for example, 15% by mass or less, preferably 13% by mass or less. The content of tin oxide in the first layer 5a can improve the stability of transparency and surface resistance.

When the second layer 5b is made of ITO, the tin oxide (SnO ₂ ) content in the second layer 5b is, for example, the total amount of tin oxide and indium oxide (In ₂ O ₃ ): It is 0.5% by mass or more, preferably 2% by mass or more, and is, for example, less than 8% by mass, preferably less than 5% by mass. If the content of tin oxide in the second layer 5b is within the above range, the crystallization of the amorphous light-transmitting conductive layer 5 can be facilitated, and the conductivity can be reliably improved.

The ratio of the thickness direction of the first layer 5a in the amorphous light-transmitting conductive layer 5 is, for example, 75% or more, preferably 80% or more, more preferably 90% or more. % or less, preferably 98% or less, more preferably 97% or less. Specifically, the thickness of the first layer 5a is, for example, 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more, and is, for example, 200 nm or less, preferably 150 nm or less, more preferably 50 nm or less.

The ratio of the second layer 5b in the thickness direction in the amorphous light-transmitting conductive layer 5 is, for example, 25% or less, preferably 20% or less, more preferably 10% or less, and for example, 1% or more. , preferably 2% or more, more preferably 3% or more. Further, specifically, the thickness of the second layer 5b is, for example, 1 nm or more, preferably 1.5 nm or more, more preferably 2 nm or more, and for example, 40 nm or less, preferably 20 nm or less, More preferably, it is 10 nm or less.

The total thickness of the amorphous light-transmissive conductive layer 5 exceeds 40 nm and is, for example, 300 nm or less. From the viewpoint of crystallization speed and resistance value during heating, it is preferably 41 nm or more, more preferably 45 nm or more, still more preferably over 50 nm, particularly preferably 60 nm or more, and preferably 250 nm or less. , more preferably 200 nm or less, still more preferably 160 nm or less, and particularly preferably 90 nm or less. From the viewpoint of crystallization suppression during storage and conductivity after heating, the thickness is preferably 100 nm or more and 180 nm or less.

The thickness of the amorphous light-transmitting conductive layer 5 can be measured by cross-sectional observation using, for example, a transmission electron microscope.

The amorphous light-transmissive conductive layer 5 is amorphous and can be converted (crystallized) into a crystalline state. Conversion to crystalline is carried out by heating as described below.

Whether the light-transmitting conductive layer is amorphous or crystalline, for example, when the light-transmitting conductive layer is an ITO layer, it is immersed in hydrochloric acid (concentration: 5% by mass) at 20°C for 15 minutes, then washed with water and dried. It can be judged by measuring the resistance between terminals for about 15 mm. In this specification, after immersion in hydrochloric acid (20 ° C., concentration: 5% by mass), washing with water, and drying, if the resistance between terminals for 15 mm exceeds 10 kΩ, the ITO layer is amorphous, and the ITO layer for 15 mm If the inter-terminal resistance is 10 kΩ or less, the ITO layer is crystalline.

6. Method for Producing Light-Transmitting Conductive Film A method for producing the light-transmitting conductive film 1 will be described. In order to manufacture the light-transmissive conductive film 1, for example, a hard coat layer 3, an optical adjustment layer 4, and an amorphous light-transmissive conductive layer 5 are placed in this order on the upper surface (one side in the thickness direction) of the transparent substrate 2. prepare. Details will be described below.

First, a known or commercially available transparent substrate 2 is prepared.

After that, from the viewpoint of the adhesion between the transparent substrate 2 and the hard coat layer 3, the transparent substrate 2 is subjected to, for example, sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc., as necessary. etching treatment and undercoating treatment can be performed. Further, the transparent substrate 2 can be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like.

Next, a hard coat layer 3 is provided on the upper surface of the transparent substrate 2 . For example, the hard coat layer 3 is formed on the lower surface of the transparent substrate 2 by wet coating the hard coat composition on the upper surface of the transparent substrate 2 .

Specifically, for example, a solution (varnish) is prepared by diluting the hard coat composition with a solvent, and then the hard coat composition solution is applied to the upper surface of the transparent substrate 2 and dried.

Examples of the solvent include organic solvents and aqueous solvents (specifically, water), and organic solvents are preferred. Examples of organic solvents include alcohol compounds such as methanol, ethanol and isopropyl alcohol; ketone compounds such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ester compounds such as ethyl acetate and butyl acetate; Ether compounds, for example, aromatic compounds such as toluene and xylene. These solvents can be used alone or in combination of two or more.

The solid content concentration in the hard coat composition solution is, for example, 1% by mass or more, preferably 10% by mass or more, and is, for example, 30% by mass or less, preferably 20% by mass or less.

The coating method can be appropriately selected according to the hard coat composition solution and the transparent substrate 2 . Examples of coating methods include dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and extrusion coating.

The drying temperature is, for example, 50° C. or higher, preferably 70° C. or higher, and for example, 200° C. or lower, preferably 100° C. or lower.

The drying time is, for example, 0.5 minutes or longer, preferably 1 minute or longer, and for example, 60 minutes or shorter, preferably 20 minutes or shorter.

Thereafter, when the hard coat composition contains an active energy ray-curable resin, the active energy ray-curable resin is cured by irradiating the active energy ray after drying the hard coat composition solution.

When the hard coat composition contains a thermosetting resin, the drying step can dry the solvent and thermoset the thermosetting resin.

Next, an optical adjustment layer 4 is provided on the upper surface of the hard coat layer 3 . For example, the optical adjustment layer 4 is formed on the upper surface of the hard coat layer 3 by wet coating the optical adjustment composition on the upper surface of the hard coat layer 3 .

Specifically, for example, a solution (varnish) is prepared by diluting the optical adjustment composition with a solvent, and then the optical adjustment composition solution is applied on the upper surface of the hard coat layer 3 and dried.

The conditions for preparation, application, drying, etc. of the optical adjustment composition can be the same as the conditions for preparation, application, drying, etc. exemplified for the hard coat composition.

Further, when the optical adjustment composition contains an active energy ray-curable resin, the active energy ray-curable resin is cured by irradiating the active energy ray after drying the optical adjustment composition solution.

In addition, when the optical adjustment composition contains a thermosetting resin, the drying step can dry the solvent and thermoset the thermosetting resin.

Next, an amorphous light-transmissive conductive layer 5 is provided on the top surface of the optical adjustment layer 4 . For example, the amorphous light-transmissive conductive layer 5 is formed on the upper surface of the optical adjustment layer 4 by a dry method.

Dry methods include, for example, a vacuum deposition method, a sputtering method, an ion plating method, and the like. Sputtering is preferred. By this method, a thin amorphous light-transmissive conductive layer 5 can be formed.

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

The power source used in the sputtering method may be, for example, a direct current (DC) power source, an alternating medium frequency (AC/MF) power source, a high frequency (RF) power source, or a high frequency power source obtained by superimposing a direct current power source.

When the sputtering method is employed, the target material includes the above-mentioned inorganic substances constituting the amorphous light-transmitting conductive layer 5, preferably ITO. From the viewpoint of the durability and crystallization of the ITO layer, the tin oxide concentration of ITO is, for example, 0.5% by mass or more, preferably 3% by mass or more, and is, for example, 15% by mass or less, preferably , 13% by mass or less.

Examples of the sputtering gas include inert gases such as Ar. Also, preferably, a reactive gas such as oxygen gas is used together. When a reactive gas is used together, the flow ratio of the reactive gas to the inert gas is, for example, 0.0010 or more and 0.0100 or less.

The sputtering method is carried out under vacuum. Specifically, the atmospheric pressure during sputtering is, for example, 1 Pa or less, preferably 0.7 Pa or less, or, for example, 0.1 Pa or more, from the viewpoints of suppressing a decrease in sputtering rate and discharge stability. .

The partial pressure of water is, for example, 10×10 ⁻⁴ Pa or less, preferably 5×10 ⁻⁴ Pa or less, from the viewpoint of improving the crystallization rate.

In order to form the desired amorphous light-transmitting conductive layer 5, sputtering may be performed multiple times by appropriately setting the target material, sputtering conditions, and the like.

In particular, in the present invention, for example, by adjusting the introduction amount of oxygen and the thickness of the amorphous light-transmitting conductive layer 5 to form the amorphous light-transmitting conductive layer 5 having a thickness exceeding 40 nm, a desired can be suitably produced.

Specifically, taking the case of forming an ITO layer as the amorphous light-transmitting conductive layer 5 by a sputtering method as an example, the ITO layer obtained by the sputtering method is generally formed as an amorphous ITO layer. be done. Then, by reducing the amount of oxygen in the film formation atmosphere and creating oxygen vacancies in the ITO layer, an ITO layer that can be crystallized by heating can be obtained. At this time, the amount of oxygen is slightly insufficient to the extent that the ITO layer can be crystallized.

More specifically, for example, when the horizontal magnetic field strength is set to a high magnetic field strength of 50 mT or more and 200 mT or less (preferably 80 mT or more and 120 mT or less) and a DC power supply is adopted, the following is the case. When forming the first layer 5a, an ITO target with a high tin oxide concentration is used, and the flow ratio of oxygen gas to Ar gas (O ₂ /Ar) is set to, for example, 0.0050 or more and 0.0120 or less, preferably , 0.0060 or more and 0.0080 or less, and the flow rate ratio “(O ₂ /Ar)/(ITO thickness)” to the ITO thickness (nm) is set to, for example, 0.00003 or more and 0.00020 or less. , and if necessary, the flow rate ratio is similarly set appropriately when the second layer 5b is formed.

Whether or not oxygen is introduced at a suitable rate (slightly insufficient amount of oxygen) in the ITO film formation environment can be obtained, for example, from the oxygen supply amount (sccm) (X-axis) and the oxygen supply amount. The surface resistance (Ω/□) (Y-axis) of the ITO obtained can be plotted on a graph and judged from the graph. That is, since the minimum neighborhood region (bottom region) of the graph has the lowest surface resistance and the ITO has a stoichiometric composition, the X-axis value slightly closer to the origin side than the minimum neighborhood region is It can be judged that the oxygen supply amount is suitable for producing the amorphous light-transmitting conductive layer 5 in the present invention.

As a result, a light-transmissive conductive film 1 having a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4, and an amorphous light-transmissive conductive layer 5 in this order in the thickness direction is obtained.

In the manufacturing method described above, the hard coat layer 3, the optical adjustment layer 4, and the amorphous light-transmitting conductive layer 5 are formed on the transparent substrate 2 while the transparent substrate 2 is conveyed by a roll-to-roll method. Alternatively, part or all of these layers may be formed by a batch method (single-wafer method). From the viewpoint of productivity, each layer is preferably formed on the transparent base material 2 while conveying the transparent base material 2 by a roll-to-roll method.

The light-transmitting conductive film (amorphous light-transmitting conductive film) 1 thus obtained has the following characteristics.

The carrier density in the amorphous light-transmitting conductive layer 5 is 40×10 ¹⁹ /cm ³ or more, preferably 42×10 ¹⁹ /cm ³ or more, more preferably 52×10 ¹⁹ /cm ³ or more, Also, for example, it is 170×10 ¹⁹ /cm ³ or less, preferably 100×10 ¹⁹ /cm ³ or less. If the carrier density is equal to or higher than the above lower limit, the crystallization rate during heating can be improved while suppressing crystallization during storage.

The hole mobility in the amorphous light-transmitting conductive layer 5 is, for example, 5 cm ² /V·s or more, preferably 10 cm ² /V·s or more, more preferably 20 cm ² /V·s or more, Also, for example, it is 40 cm ² /V·s or less, preferably 30 cm ² /V·s or less.

The specific resistance of the amorphous light-transmitting conductive layer 5 is, for example, 10×10 ⁻⁴ Ω·cm or less, preferably 5×10 ⁻⁴ Ω·cm or less. ⁻⁴ Ω·cm or more. If the specific resistance is equal to or less than the above upper limit, the resistance value is small and the conductivity is excellent. A specific resistance can be measured by a four-probe method.

The total light transmittance (JIS K 7375-2008) of the light-transmitting conductive film 1 is, for example, 80% or more, preferably 85% or more.

The thickness of the light-transmissive conductive film 1 is, for example, 2 μm or more, preferably 10 μm or more, and is, for example, 100 μm or less, preferably 50 μm or less.

The light-transmissive conductive film 1 is provided, for example, in an optical device. Examples of the optical device include an image display device and a light control device, and preferably an image display device. When the light-transmissive conductive film 1 is provided in an image display device (specifically, an image display device having an image display element such as an LCD module), the light-transmissive conductive film 1 is used as a touch panel substrate, for example. Used. Touch panels may be of various types, such as an optical system, an ultrasonic system, a capacitive system, and a resistive film system, and are particularly suitable for capacitive touch panels.

In particular, when the light-transmissive conductive film 1 is used as a substrate for a touch panel, the light-transmissive conductive film 1 is preferably subjected to heat treatment.

In the heat treatment, for example, the light-transmissive conductive film 1 is heated in the atmosphere.

Heat treatment can be performed 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 is, for example, 200° C. or lower, preferably 150° C. or lower.

The heating time is appropriately determined depending on the heating temperature, and is, for example, 5 minutes or longer, preferably 10 minutes or longer, and is, for example, 60 minutes or shorter, preferably 30 minutes or shorter.

Thereby, the amorphous light-transmitting conductive layer 5 is crystallized to form a crystalline light-transmitting conductive layer 6 with improved conductivity. That is, as shown in FIG. 2, a crystalline light-transmitting conductive film 7 having a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4, and a crystalline light-transmitting conductive layer 6 in this order in the thickness direction is obtained. .

The surface resistance of the crystalline light-transmitting conductive layer 6 is, for example, 60 Ω/□ or less, preferably 40 Ω/□ or less, and is, for example, 1 Ω/□ or more. Surface resistance can be measured by a four-probe method. Thereby, it is excellent in conductivity.

It should be noted that the light-transmitting conductive film 1 (or the crystalline light-transmitting conductive film 7) may be patterned as necessary.

A known etching method can be employed in the patterning process. The etching method may be either wet etching or dry etching, but wet etching is preferred from the viewpoint of production efficiency.

Examples of the shape of the pattern of the amorphous light-transmitting conductive layer 5 (or the crystalline light-transmitting conductive layer 6) include an electrode pattern and a wiring pattern having a stripe shape.

In this light-transmitting conductive film 1, the thickness of the amorphous light-transmitting conductive layer 5 exceeds 40 nm, and the carrier density in the amorphous light-transmitting conductive layer 5 is 40×10 ¹⁹ /cm ³ . That's it. Therefore, both the crystallization speed during heating and the storage stability can be achieved. That is, when the light-transmitting conductive film 1 is heated to convert the amorphous light-transmitting conductive layer 5 into the crystalline light-transmitting conductive layer 6, the speed is favorable. Therefore, the crystalline light-transmitting conductive film 7 can be obtained in a short time. In addition, during storage in a low-temperature environment (for example, 80° C. or lower) before heating, spontaneous crystallization of the amorphous light-transmitting conductive layer 5 can be suppressed, and the amorphous light-transmitting conductive layer 5 can be prevented from Partial crystallization can be suppressed. Therefore, during heating (crystallization) after storage, cracks due to the boundary between the crystalline portion and the amorphous portion that may occur during storage can be suppressed.

Therefore, the light-transmissive conductive film 1 can be crystallized in a short time while suppressing cracks in the light-transmissive conductive layer 5 even after being stored for a certain period of time. Excellent for Furthermore, after crystallization by heating, the resistance of the crystalline light-transmitting conductive film 7 can be reduced, and the conductivity can be improved.

<Modification>
In the above-described embodiment, the light-transmitting conductive film 1 includes the transparent substrate 2, the hard coat layer 3, the optical adjustment layer 4, and the amorphous light-transmitting conductive layer 5. 1 may further comprise layers other than these.

For example, although one embodiment exposes the lower surface of the transparent substrate 2, for example, the light-transmissive conductive film 1 further comprises other functional layers, such as an anti-blocking layer, on the lower surface of the transparent substrate 2. may be

In addition, the light-transmitting conductive film 1 of one embodiment includes a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4, and an amorphous light-transmitting conductive layer 5. For example, the hard coat layer 3 and at least one of the optical adjustment layer 4 may not be provided. Preferably, the hard coat layer 3 and the optical adjustment layer 4 are provided from the viewpoints of abrasion resistance, visibility suppression of the pattern in the amorphous light-transmitting conductive layer 5, and the like.

EXAMPLES Examples and comparative examples are shown below to describe the present invention more specifically. It should be noted that the present invention is by no means limited to Examples and Comparative Examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( Content ratio), physical properties, parameters, etc. be able to.

(Example 1)
A cycloolefin polymer (COP) film (manufactured by Zeon Co., Ltd., trade name “Zeonor”, thickness 40 μm) was prepared as a transparent substrate. An ultraviolet curable resin composition composed of an acrylic resin was applied to the upper surface of the transparent base material and irradiated with ultraviolet rays to form a hard coat layer (thickness: 1 μm). Subsequently, an ultraviolet curable composition containing zirconia particles was applied on the upper surface of the hard coat layer and irradiated with ultraviolet rays to form an optical adjustment layer (thickness: 90 nm, refractive index: 1.62). As a result, a laminate including a transparent substrate, a hard coat layer and an optical adjustment layer was obtained.

A first layer (thickness: 43 nm) made of an indium-tin composite oxide (ITO) layer was formed on the upper surface of the optical adjustment layer of the laminate using a vacuum sputtering device. Specifically, the inside of the vacuum sputtering apparatus is evacuated until the partial pressure of water becomes 2.0×10 ⁻⁴ Pa or less, and then a mixed gas of argon gas and oxygen (flow ratio: O ₂ /Ar= 0.00763, (O ₂ /Ar)/ITO thickness ratio: 0.000178) was introduced, and DC magnetron sputtering was performed on the laminate in an atmosphere of pressure 0.4 Pa. A sintered body of 10 mass % tin oxide/90 mass % indium oxide was used as a target. Also, the horizontal magnetic field on the target surface was set to 100 mT.

Subsequently, the target was changed to a sintered body of 3% by mass of tin oxide/97% by mass of indium oxide, and the flow ratio of the mixed gas of argon gas and oxygen was changed to O ₂ /Ar = 0.00160. Sputtering was further performed in the same manner as above to form a second layer (thickness: 2 nm) on the upper surface of the first layer. As a result, an amorphous light-transmitting conductive layer (amorphous transparent conductive layer) having a total thickness of 45 nm was formed on the upper surface of the optical adjustment layer.

Thus, a light-transmissive conductive film (transparent conductive film) of Example 1 was produced.

(Examples 2-5 and Comparative Examples 1-4)
A light-transmissive conductive film was produced in the same manner as in Example 1, except that the thickness of each layer and the gas flow rate ratio were changed as shown in Table 1 in the formation of the first layer and the second layer. In Examples 4 and 5 and Comparative Examples 2 and 4, a polyethylene terephthalate (PET) film (thickness: 23 μm) was used as the transparent substrate.

(1) Measurement of thickness The thicknesses of the hard coat layer, the optical adjustment layer, the first layer, and the second layer were measured by cross-sectional observation using a transmission electron microscope (manufactured by Hitachi, Ltd., "H-7650"). . The thickness of the transparent substrate was measured using a film thickness gauge (manufactured by Peacock, "Digital Dial Gauge DG-205").

(2) Measurement of Carrier Density/Hall Mobility A Hall effect measurement system (“HL5500PC” manufactured by Biorad) was used to measure the Hall mobility of the amorphous light-transmitting conductive layer. The carrier density was calculated using the total thickness of the amorphous light-transmitting conductive layer.

(3) Measurement of specific resistance The non-resistance of the amorphous light-transmitting conductive layer was measured by a four-probe method. Table 1 shows the results.

(4) Evaluation of crystallization rate in heating The light-transmissive conductive film of each example and each comparative example was heated in a hot air oven at 140°C for 30 minutes or 60 minutes to prepare samples. This sample was immersed in hydrochloric acid having a concentration of 5 wt % at 35° C. for 15 minutes, then washed with water and dried. At this time, when the inter-terminal resistance was 10 kΩ or less, it was determined that the crystallization of the amorphous light-transmitting conductive layer was completed.

A case where the crystallization completion time was 30 minutes or less was evaluated as ⊚, and a case where the crystallization completion time exceeded 30 minutes and was 60 minutes or less was evaluated as ◯. The case of exceeding 60 minutes was evaluated as x. Table 1 shows the results.

(5) Evaluation of storability (inhibition of crystallization during standing) For the light-transmissive conductive films of each example and each comparative example, Sample 1 was left at 50°C for 15 hours and at 80°C for 6 hours. Sample 2 was prepared respectively. These samples were further crystallized by heating in a hot air oven at 150° C. for 90 minutes. The surface of the light-transmitting conductive layer of this crystallized sample was observed with an optical microscope (magnification: 100, observation area: 2 cm square) to confirm the presence or absence of cracks.

A case where no cracks were observed in both sample 1 and sample 2 was evaluated as ⊚, a case in which no cracks were observed only in sample 1 was evaluated as ◯, and cracks were observed in both sample 1 and sample 2. was evaluated as ×. Table 1 shows the results.

(6) Evaluation of conductivity after crystallization The light-transmitting conductive film of each example and each comparative example was heated in a hot air oven at 140°C for 120 minutes to crystallize the amorphous light-transmitting conductive layer. let me The surface resistance of the light-transmissive conductive film of this crystallized sample was measured by a four-probe method. A case where the surface resistance is 40Ω/□ or less is evaluated as ◎, a case where the surface resistance exceeds 40Ω/□ and is 60Ω/□ or less is evaluated as ◯, and a case where the surface resistance exceeds 60Ω/□ is evaluated as ◯. It was evaluated as ×. Table 1 shows the results.

1 Light-transmitting conductive film 2 Transparent substrate 5 Amorphous light-transmitting conductive layer

Claims (3)

comprising a transparent base material and an amorphous light-transmitting conductive layer arranged on one side in the thickness direction of the transparent base material,
The amorphous light-transmitting conductive layer is capable of being converted to crystalline,
The thickness of the amorphous light-transmitting conductive layer is more than 40 nm and 300 nm or less,
A light-transmitting conductive film, wherein the amorphous light-transmitting conductive layer has a carrier density of 46 × 10 ¹⁹ /cm ³ or more. 2. The light-transmitting conductive film according to claim 1, wherein the amorphous light-transmitting conductive layer contains an indium-based inorganic oxide. 3. The light-transmitting property according to claim 1, wherein the amorphous light-transmitting conductive layer is an indium-based inorganic oxide layer containing indium and one or more impure inorganic elements. conductive film.

Images