JP2020107542A - Transparent conductive film and crystalline transparent conductive film - Google Patents

Abstract

To provide a transparent conductive film having a good crystallization rate under low temperature and excellent in conductivity.SOLUTION: A transparent conductive film 1 includes a transparent substrate 2 and a transparent conductive layer 5 to be disposed on an upper side of the transparent substrate 2. The transparent conductive layer 5 is amorphous. The transparent conductive layer 5 includes an Hf region 8 including an indium-based oxide containing hafnium and an Sn region 6 including an indium-based oxide containing tin in a thickness direction thereof.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a transparent conductive film and a crystalline transparent conductive film, and more particularly, to a transparent conductive film and a crystalline transparent conductive film which are preferably used for optical applications.

Conventionally, a transparent conductive film in which a transparent conductive layer made of indium tin composite oxide (ITO) is formed in a desired electrode pattern has been used for optical applications such as a touch panel. Further, in recent years, an electromagnetic wave generated by a current flowing through a touch panel affects an image display device such as an OLED or LCD. Therefore, in order to shield the electromagnetic wave, a non-patterned transparent film is provided between the touch panel and the image display device. Placing a conductive film has also been proposed.

As the transparent conductive film, for example, in Patent Document 1, a transparent conductive film including a transparent resin film, a hard coat layer, an intermediate layer having a refractive index of 1.65 to 1.90, and a transparent conductive layer in order. Is disclosed.

JP, 2017-62609, A

In general, a transparent conductive film including ITO crystallizes ITO by heating to improve conductivity (low resistance).

On the other hand, a cycloolefin film may be used as the transparent resin film from the viewpoint of having various functions such as transparency and polarization. However, since such a cycloolefin film has a low glass transition point and low heat resistance, it cannot be heat-treated at a high temperature. Further, if the heating is performed at a low temperature, the productivity becomes poor if the heating time becomes long.

The present invention is to provide a transparent conductive film having a good crystallization rate at low temperature and excellent conductivity.

The present invention [1] includes a transparent base material and a transparent conductive layer disposed on one side in the thickness direction of the transparent base material, the transparent conductive layer is amorphous, and the transparent conductive layer is A transparent conductive film having a Hf region made of an indium oxide containing hafnium and a Sn region made of an indium oxide containing tin in the thickness direction is included.

The present invention [2] includes the transparent conductive film according to [1], wherein the Hf region is arranged on one side in the thickness direction of the Sn region.

The present invention [3] includes the transparent conductive film according to [1] or [2], wherein the transparent conductive layer has a thickness of 10 nm or more and 35 nm or less.

In the present invention [4], the transparent substrate includes the transparent conductive film according to any one of [1] to [3], which is a cycloolefin film.

The present invention [5] includes a crystalline transparent conductive film obtained by crystallizing the transparent conductive layer of the transparent conductive film according to any one of [1] to [4].

According to the transparent conductive film of the present invention, a transparent base material and a transparent conductive layer are provided, and the transparent conductive layer is formed of an Hf region made of an indium oxide containing hafnium and an indium oxide containing tin. And a Sn region in the thickness direction. Therefore, the crystallization rate at a low temperature is good and the conductivity is excellent.

Further, according to the crystalline transparent conductive film of the present invention, the productivity is good and the conductivity is excellent.

FIG. 1 shows a cross-sectional view of a first embodiment of the transparent conductive film of the present invention. FIG. 2 shows a crystalline transparent conductive film obtained by crystallizing the transparent conductive film shown in FIG. FIG. 3 shows a modified example of the first embodiment of the transparent conductive film of the present invention (a mode having no Sn/Hf mixed region). FIG. 4 shows a sectional view of a second embodiment of the transparent conductive film of the present invention. FIG. 5 shows a sectional view of a third embodiment of the transparent conductive film of the present invention. FIG. 6 shows a graph of the transparent conductive layer of the transparent conductive film of Example 1, measured by X-ray photoelectron spectroscopy. FIG. 7 shows a graph in which the crystallization rate was measured for each Example and each Comparative Example.

<First Embodiment>
An embodiment of the first embodiment of the transparent conductive film of the present invention will be described with reference to 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, one side in 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). Further, the left-right direction and the depth direction of the paper are plane directions orthogonal to the up-down direction. Specifically, it is based on the directional arrow in each figure.

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. Have. The transparent conductive film 1 is, for example, one component such as a base material for a touch panel or an electromagnetic wave shield included in an image display device, that is, it is not an image display device. That is, the transparent conductive film 1 is a component for manufacturing an image display device and the like, does not include an image display element such as an OLED module, and includes a transparent base material 2, a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive film. It is a device that includes the layer 5 and is distributed industrially as a component and is industrially usable.

Specifically, as shown in FIG. 1, the transparent conductive film 1 includes a transparent base material 2, a hard coat layer 3 disposed on the upper surface (one surface in the thickness direction) of the transparent base material 2, and a hard coat layer. The optical adjustment layer 4 is provided on the upper surface of the optical adjustment layer 3, and the transparent conductive layer 5 is provided on the upper surface of the optical adjustment layer 4. More specifically, the transparent conductive film 1 includes a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in this order. The transparent conductive film 1 preferably comprises a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4 and a transparent conductive layer 5.

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

The transparent substrate 2 is the lowermost layer of the transparent conductive film 1 and has a film shape. The transparent substrate 2 is arranged on the entire lower surface of the hard coat layer 3 so as to contact the lower surface of the hard coat layer 3.

The transparent substrate 2 is, for example, a polymer film having transparency. Examples of the material of the transparent substrate 2 include olefin resins such as polyethylene, polypropylene and cycloolefin polymers, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, such as polymethacrylate ( Examples of the (meth)acrylic resin (acrylic resin and/or methacrylic resin) include polycarbonate resin, polyether sulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. The transparent substrate 2 can be used alone or in combination of two or more.

Preferably, a non-crystalline thermoplastic resin is used. Thereby, it is possible to have a desired polarization axis. Also, the transparency is excellent.

As such an amorphous thermoplastic resin, a cycloolefin polymer is preferably mentioned. That is, the transparent substrate 2 is preferably a cycloolefin-based film formed from a cycloolefin polymer.

The cycloolefin-based polymer is a polymer obtained by polymerizing a cycloolefin monomer and having an alicyclic structure in the repeating unit of the main chain. The cycloolefin-based resin is preferably an amorphous cycloolefin-based resin.

Examples of the cycloolefin-based polymer include a cycloolefin homopolymer made of a cycloolefin monomer, for example, a cycloolefin copolymer made of a copolymer of a cycloolefin monomer and an olefin such as ethylene.

Examples of the cycloolefin monomer include polycyclic olefins such as norbornene, methylnorbornene, dimethylnorbornene, ethylidene norbornene, butylnorbornene, dicyclopentadiene, dihydrodicyclopentadiene, tetracyclododecene, and tricyclopentadiene, for example, cyclobutene, Examples thereof include monocyclic olefins such as cyclopentene, cyclohexadiene, and cyclooctatriene. Preferably, a multi-dry olefin is used. These cycloolefins can be used alone or in combination of two or more.

The glass transition point (Tg) of the transparent substrate 2 is, for example, 150° C. or lower, preferably 120° C. or lower, and is, for example, 50° C. or higher, preferably 70° C. or higher.

The transparent substrate 2 preferably has a polarization axis in the plane direction. Thereby, even when the image display device including the transparent conductive film 1 is viewed through polarizing glasses (such as sunglasses), crossed Nicols between the polarizing glasses and the polarizer in the image display device is suppressed, and the image display device is Can be seen.

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 substrate 2 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 150 μm or less, from the viewpoint of mechanical strength and the like. The thickness of the transparent substrate 2 can be measured using, for example, a micro gauge type thickness gauge.

4. Hard coat layer The hard coat layer 3 is a protective layer for preventing the transparent base material 2 from being scratched when the transparent conductive film 1 is manufactured. Further, it is a scratch-resistant layer for suppressing the occurrence of scratches on the transparent conductive layer 5 when a plurality of transparent 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 base material 2 so as to contact the upper surface of the transparent base material 2. More specifically, the hard coat layer 3 is arranged between the transparent base material 2 and the optical adjustment layer 4 so as to contact the upper surface of the transparent base material 2 and the lower surface of the optical adjustment layer 4.

The hard coat layer 3 is formed of a hard coat composition. The hard coat composition contains a resin.

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

Examples of the curable resin include active energy ray curable resins that are cured by irradiation with active energy rays (specifically, ultraviolet rays, electron beams, etc.), such as thermosetting resins that are 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 a functional group include a vinyl group and a (meth)acryloyl group (methacryloyl group and/or acryloyl group).

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

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

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

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

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

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

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 for example, 10 μm or less, preferably 3 μm or less. The thickness of the hard coat layer 3 can be calculated, for example, based on the wavelength of the interference spectrum observed using an instantaneous multi-photometry system (for example, "MCPD2000" manufactured by Otsuka Electronics Co., Ltd.).

4. Optical Adjustment Layer The optical adjustment layer 4 ensures excellent transparency of the transparent conductive film 1 while suppressing the pattern visibility of the transparent conductive layer 5 and suppressing reflection at the interface in the transparent conductive film 1. Therefore, it is a layer for adjusting the optical physical properties (eg, refractive index) of the transparent conductive film 1.

The optical adjustment layer 4 has a film shape, and is arranged on the entire upper surface of the hard coat layer 3 so as to contact the upper surface of the hard coat layer 3. More specifically, the optical adjustment layer 4 is arranged between the hard coat layer 3 and the transparent conductive layer 5 so as to contact the upper surface of the hard coat layer 3 and the lower surface of the transparent conductive layer 5.

The optical adjustment layer 4 is formed of an optical adjustment composition. The optical adjustment composition contains a resin, and preferably contains a resin and particles. That is, the optical adjustment layer 4 is preferably a resin layer containing particles.

Examples of the resin include the resins exemplified for the hard coat composition. A curable resin is preferable, an active energy ray curable resin is more preferable, and a (meth)acrylic UV 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 with respect 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 the refractive index, inorganic particles are preferable, metal oxide particles are more preferable, and zirconium oxide particles (ZrO ₂ ) are more preferable.

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

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

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 by, for example, 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 calculated, for example, based on the wavelength of the interference spectrum observed using the instantaneous multi-photometry system.

5. Transparent Conductive Layer The transparent conductive layer 5 is a transparent layer that is crystallized as needed to exhibit excellent conductivity.

The transparent conductive layer 5 is the uppermost layer of the transparent conductive film 1 and has a film shape. The transparent conductive layer 5 is arranged on the entire upper surface of the optical adjustment layer 4 so as to contact the upper surface of the optical adjustment layer 4.

The transparent conductive layer 5 has a Sn region 6, a Sn/Hf mixed region 7, and an Hf region 8 in order from the lower side.

The Sn region 6 is a lower layer formed on the upper surface of the optical adjustment layer 4 so as to extend in the surface direction. The Sn region 6 is formed of an indium-based oxide containing tin (Sn), and preferably formed of an indium tin composite oxide (ITO).

In the Sn region 6, the tin oxide (SnO ₂ ) content is, for example, 0.5% by mass or more, and preferably 3% by mass or more, based on the total amount of tin oxide and indium oxide (In ₂ O ₃ ). And, for example, 15% by mass or less, preferably 13% by mass or less. When the content of tin oxide is at least the above lower limit, the crystallization rate of the transparent conductive layer 5 can be improved. When the content of tin oxide is at most the above upper limit, the conductivity of the transparent conductive layer 5 can be improved.

The Sn region 6 may contain an unavoidable impurity as a metal other than Sn and In.

Further, the Sn region 6 does not substantially contain Hf. That is, in the Sn region 6, the Hf element is not detected in the measurement by X-ray photoelectron spectroscopy.

The thickness of the Sn region 6 is, for example, 1 nm or more, preferably 3 nm or more, preferably 10 nm or more, and for example, 50 nm or less, preferably 40 nm or less, more preferably 30 nm or less. The thickness of each region can be determined by measuring the transparent conductive layer 5 in the thickness direction by X-ray photoelectron spectroscopy.

In the Sn/Hf mixed region 7, the intermediate layer is formed above the Sn region 6 so as to extend in the surface direction. In the Sn/Hf mixed region 7, both the element contained in the Sn region 6 and the element contained in the Hf region 8 are mixed. Specifically, it is formed from an oxide containing Sn, Hf and In. Further, the Sn/Hf mixed region 7 may contain Ta (tantalum), in which case it is formed from an oxide containing Sn, Hf, Ta and In.

Preferably, the Sn/Hf mixed region 7 is a region that gradually changes from the Sn region 6 to the Hf region 8. That is, as the Sn/Hf mixed region 7 goes from the lower end to the upper end, the Sn element content ratio gradually decreases and the Hf content ratio gradually increases. In other words, the cross section in the transparent conductive layer 5 has no interface. That is, the transparent conductive layer 5 does not have both the Sn region-Sn/Hf mixed region interface (6/7 interface) and the Sn/Hf mixed region-Hf region interface (7/8 interface).

The thickness of the Sn/Hf mixed region 7 is, for example, 1 nm or more, preferably 2 nm or more, preferably 3 nm or more, and for example, 10 nm or less, preferably 8 nm or less, more preferably 6 nm or less. ..

The Hf region 8 is an upper layer formed on the upper side of the Sn/Hf mixed region 7 so as to extend in the surface direction. The Hf region 8 is formed of an indium oxide containing hafnium (Hf), preferably an oxide containing Hf, Ta (tantalum) and In.

When Ta is not included, the Hf content ratio (atomic ratio) is, as Hf/(Hf+In), for example, 0.2 at% or more, preferably 0.5 at% or more, and, for example, 3.0 at%. Hereafter, it is preferably 2.5 at% or less.

On the other hand, the content ratio (atomic ratio) of Hf is, in the case of containing Ta, Hf/(Hf+Ta+In), for example, 0.2 at% or more, preferably 0.5 at% or more, and, for example, 3.0 at. % Or less, preferably 2.5 at% or less.

The Ta content ratio (atomic ratio) is, as Ta/(Hf+Ta+In), for example, 0.02 at% or more, preferably 0.1 at% or more, and for example, 1.3 at% or less, preferably 1 It is 0.0 at% or less.

The content ratio (atomic ratio) of In is, as In/(Hf+In) or In/(Hf+Ta+In), for example, 95.0 at% or more, preferably 97.0 at% or more, and for example, 99.7 at%. Hereafter, it is preferably 99.0 at% or less.

The Hf region 8 may contain an unavoidable impurity as a metal other than Hf, Ta, and In.

Moreover, the Hf region 8 does not substantially contain Sn. That is, in the Hf region 8, Sn element is not detected in the measurement by X-ray photoelectron spectroscopy.

The thickness of the Hf region 8 is, for example, 1 nm or more, preferably 3 nm or more, preferably 8 nm or more, and for example, 50 nm or less, preferably 40 nm or less, more preferably 30 nm or less.

The Hf region 8 is preferably thicker than the Sn region 6. Thereby, the crystallization rate at a low temperature is further excellent.

The surface resistivity of the upper surface of the transparent conductive layer 5 is, for example, 100Ω/□ or less, preferably 80Ω/□ or less, and for example, 10Ω/□ or more. The surface resistivity can be measured by the 4-terminal method.

The specific resistance of the upper surface of the transparent conductive layer 5 is, for example, 3.0×10 ⁻⁴ Ω·cm or less, preferably 2.5×10 ⁻⁴ Ω·cm or less, and, for example, 1.0×. It is 10 ⁻⁴ Ω·cm or more. The specific resistance can be measured by the 4-terminal method.

The total thickness of the transparent conductive layer 5 is, for example, 5 nm or more, preferably 10 nm or more, and for example, 80 nm or less, preferably 35 nm or less. By setting the thickness of the transparent conductive layer 5 within the above range, it is possible to more reliably achieve both the crystallization rate and the conductivity at low temperature. The total thickness of the transparent conductive layer 5 can be measured, for example, by observing the cross section of the transparent conductive film 1 using a transmission electron microscope.

The transparent conductive layer 5 is amorphous. The amorphous property of the transparent conductive layer 5 is obtained by, for example, immersing the transparent conductive film 1 in hydrochloric acid (20° C., concentration 5% by mass) for 15 minutes, followed by washing with water and drying, and then the transparent conductive layer 5 side. It can be judged by measuring the resistance between terminals for about 15 mm with respect to the surface. In the transparent conductive film 1 after immersion, washing with water and drying, when the inter-terminal resistance for 15 mm exceeds 10 kΩ, the transparent conductive layer 5 is amorphous, and when the resistance is 10 kΩ or less, the transparent conductive film The layer is crystalline.

6. Method for manufacturing transparent conductive film A method for manufacturing the transparent conductive film 1 will be described. To manufacture the transparent conductive film 1, for example, the hard coat layer 3, the optical adjustment layer 4, and the transparent conductive layer 5 are provided in this order on the upper surface of the transparent substrate 2. The details will be described below.

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

Then, if necessary, from the viewpoint of adhesion between the transparent base material 2 and the hard coat layer 3, for example, sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion may be performed on the upper surface of the transparent base material 2. Etching treatment such as oxidation, or undercoating treatment can be performed. Further, the transparent substrate 2 can be removed of dust and cleaned by solvent cleaning, ultrasonic cleaning, or the like.

Next, the 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 upper surface of the transparent substrate 2 by wet-coating the upper surface of the transparent substrate 2 with the hard coat composition.

Specifically, for example, a solution (varnish) prepared by diluting the hard coat composition with a solvent is prepared, and subsequently, 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 preferably organic solvents. Examples of the organic solvent 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, and propylene glycol monomethyl ether. Examples thereof include ether compounds, for example, aromatic compounds such as toluene and xylene. These solvents can be used alone or in combination of two or more kinds.

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 for example, 30% by mass or less, preferably 20% by mass or less.

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

The drying temperature is, for example, 50° C. or higher, preferably 70° C. or higher, and for example, 150° C. or lower, preferably 100° C. or lower.

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

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

When the hard coat composition contains a thermosetting resin, this drying step allows the thermosetting resin to be thermoset together with the drying of the solvent.

Next, the optical adjustment layer 4 is provided on the upper surface of the hard coat layer 3. For example, the optical adjustment composition is wet coated on the upper surface of the hard coat layer 3 to form the optical adjustment layer 4 on the upper surface of the hard coat layer 3.

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

The conditions such as preparation, coating and drying of the optical adjustment composition can be the same as the conditions such as preparation, coating and drying exemplified for the hard coat composition.

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

In addition, when the optical adjustment composition contains a thermosetting resin, the thermosetting resin can be thermoset by this drying step together with the drying of the solvent.

Next, the transparent conductive layer 5 is provided on the upper surface of the optical adjustment layer 4. For example, the transparent conductive layer 5 is formed on the upper surface of the optical adjustment layer 4 by a dry method.

In forming the transparent conductive layer 5, the Sn region 6 and the Hf region 8 are formed in this order. Preferably, the Sn region 6 and the Hf region 8 are continuously formed by the same dry method. As a result, components are mixed with each other at the interface between the Sn region 6 and the Hf region 8 to form the Sn/Hf mixed region 7.

Examples of the dry method include a vacuum vapor deposition method, a sputtering method, an ion plating method and the like. Preferably, the sputtering method is used. A desired transparent conductive layer 5 can be formed by this method.

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. Preferably, a magnetron sputtering method is used.

As a target material for forming the Sn region 6, an indium-based oxide containing Sn can be cited. Preferably, ITO (In-Sn-containing oxide) is used.

In forming the Sn region 6, the sputtering gas may be, for example, an inert gas such as Ar. If necessary, a reactive gas such as oxygen gas can be used together. When the reactive gas is used in combination, the flow rate ratio of the reactive gas is, for example, 0.1 flow% or more and 5 flow% or less with respect to the total flow ratio of the sputtering gas and the reactive gas.

The sputtering method is performed under vacuum. Specifically, the atmospheric pressure during sputtering is, for example, 1 Pa or less, and preferably 0.7 Pa or less, from the viewpoint of suppressing a decrease in sputtering rate, discharge stability, and the like.

The power source used in the sputtering method may be, for example, a DC power source, an AC power source, an MF power source, an RF power source, or a combination thereof.

The set thickness (target value) of the sputtering device is, for example, 5 nm or more, preferably 10 nm or more, more preferably 12 nm or more, and for example, 50 nm or less, preferably 30 nm or less, more preferably DC, 20 nm. It is as follows.

In the formation of the Hf region 8, the target material may be an indium oxide containing Hf. An oxide containing In, Hf, and Ta (In-Hf-Ta-containing oxide) is preferable. Specific examples of such a target include oxide sintered bodies described in JP-A-10-269843, JP-A-2017-149636, JP-A-2018-188677 and the like.

The set thickness of the sputtering device is, for example, 5 nm or more, preferably 10 nm or more, more preferably 15 nm or more, and for example, 50 nm or less, preferably 30 nm or less, more preferably 25 nm or less.

In the formation of the Hf region 8, the conditions of the sputtering method are the same as those of the formation of the Sn region 6 except for the above.

In addition, in order to form the transparent conductive layer 5 having a desired thickness, the target material, the conditions of sputtering, and the like may be appropriately set and the sputtering may be performed plural times.

Further, in the above manufacturing method, the hard coat layer 3, the optical adjustment layer 4, and the transparent conductive layer 5 may be formed on the transparent substrate 2 while the transparent substrate 2 is being transported by a roll-to-roll method. Alternatively, a part or all of these layers may be formed by a batch method (single wafer method). From the viewpoint of productivity, preferably, each layer is formed on the transparent substrate 2 by a roll-to-roll method while the transparent substrate 2 is being transported.

Thus, as shown in FIG. 1, a transparent conductive film 1 (amorphous transparent conductive film) including a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4 and a transparent conductive layer 5 in order is obtained. To be The transparent conductive layer 5 is amorphous, and includes a Sn region 6, a Sn/Hf mixed region 7 and a Hf region 8 in order from the bottom.

The thickness of the resulting transparent conductive film 1 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 100 μm or less, preferably 50 μm or less.

In this transparent conductive film 1, since the transparent conductive layer 5 has the Hf region 8 and the Sn region 6 in the thickness direction, it is possible to achieve both excellent crystallization rate and conductivity. That is, the transparent conductive layer 5 can be crystallized at a low temperature in a short time, and the crystallized transparent conductive film 1 (crystalline transparent conductive film 1A, see FIG. 2) exhibits excellent conductivity. To do.

7. Crystalline transparent conductive film A method for producing the crystalline transparent conductive film 1A will be described. To manufacture the crystalline transparent conductive film 1A, the transparent conductive film 1 is heated.

Specifically, the transparent conductive film 1 is heated in the atmosphere.

The heating can be performed using, for example, an infrared heater or an oven.

The heating temperature is, for example, 80° C. or higher, preferably 90° C. or higher, and for example, 150° C. or lower, preferably 120° C. or lower, more preferably 100° C. or lower. When the heating temperature is at least the above lower limit, the transparent conductive layer 5 can be surely crystallized, and the crystalline transparent conductive layer 5A can be surely obtained. On the other hand, if the heating temperature is equal to or lower than the above upper limit, heat damage to the transparent substrate 2 can be suppressed.

The heating time is, for example, 1 minute or more, preferably 10 minutes or more, and for example, 60 minutes or less, preferably 30 minutes or less. When the heating time is at least the above lower limit, the transparent conductive layer 5 can be reliably crystallized. On the other hand, if the heating temperature is at most the above upper limit, the production efficiency of the crystalline transparent conductive film 1A will be excellent.

As a result, the transparent conductive layer 5 is crystallized and the crystalline transparent conductive layer 5A is formed. That is, the crystalline transparent conductive film 1A is obtained.

As shown in FIG. 2, the crystalline transparent conductive film 1A includes a transparent base material 2, a hard coat layer 3, an optical adjustment layer 4, and a crystalline transparent conductive layer 5A in order from the bottom.

The crystalline transparent conductive layer 5A is crystalline and includes a Sn region 6A, a Sn/Hf mixed region 7A, and an Hf region 8A in order from the bottom. The element ratio and thickness of each region in the crystalline transparent conductive layer 5A are the same as the element ratio and thickness of each region of the amorphous transparent conductive layer 5.

The surface resistance of the upper surface of the crystalline transparent conductive layer 5A is, for example, 100Ω/□ or less, preferably 80Ω/□ or less, and for example, 10Ω/□ or more.

Such a transparent conductive film 1 and a crystalline transparent conductive film 1A are provided, for example, in an optical device. Examples of the optical device include an image display device. When the transparent conductive film 1 or the crystalline transparent conductive film 1A is provided in an image display device (specifically, an image display device having an image display element such as an OLED module or an LCD module), these films (1 1A) is patterned as necessary and is used as, for example, an electromagnetic wave shield, a touch panel substrate, or the like. Preferably, it is used as an electromagnetic wave shield. When used as a base material for a touch panel, examples of the format of the touch panel include various methods such as an optical method, an ultrasonic method, an electrostatic capacity method, and a resistance film method, and are suitably used for the electrostatic capacity type touch panel. To be

8. Modified Example (1) In the embodiment shown in FIG. 1, the transparent conductive layer 5 has the Sn/Hf mixed region 7 arranged between the Sn region 6 and the Hf region 8. As shown in, the Sn/Hf mixed region 7 may not be provided.

As shown in FIG. 3, the transparent conductive layer 5 includes a Sn region 6 and an Hf region 8 arranged on the upper surface thereof.

The transparent conductive layer 5 has an interface 9 between the lower layer and the upper layer. The interface 9 can observe the cross section of the transparent conductive layer 5 using a transmission electron microscope (TEM) or a scanning electron microscope (SEM), for example.

(2) In the embodiment shown in FIG. 1, the Sn region 6 does not substantially have a Sn element concentration gradient in the thickness direction, but although not shown, the Sn region 6 does not have Sn concentration in the thickness direction. It may have a concentration gradient. In the Sn region 6, the Sn concentration at the upper end may be lower or higher than the Sn concentration at the lower end. Preferably, the Sn concentration at the upper end is lower than the Sn concentration at the lower end. For example, such an embodiment can be obtained by sequentially depositing two or more types of targets having different Sn content ratios when depositing the Sn region 6 by the sputtering method.

(3) In the embodiment shown in FIG. 1, the transparent conductive film 1 includes a transparent substrate 2, a hard coat layer 3, an optical adjustment layer 4 and a transparent conductive layer 5. For example, although not shown, the hard coat layer One or both of 3 and the optical adjustment layer 4 may not be provided. From the viewpoint of scratch resistance, optical characteristics, etc., the embodiment shown in FIG. 1 is preferable.

Although not shown, the transparent conductive film 1 may further include another functional layer such as an anti-blocking layer or two or more functional layers on the lower surface of the transparent substrate 2.

(4) The crystalline transparent conductive film 1A shown in FIG. 2 can also have the same configuration as the above (1) to (3).

<Second to Third Embodiments>
One embodiment of the second to third embodiments of the transparent conductive film of the present invention will be described with reference to FIGS. 4 to 5. In the second to third embodiments, the same members and steps as those in the above-described first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. Further, also in the second embodiment, the same operational effect as in the first embodiment can be obtained. Further, similarly, the modified example of the first embodiment can be appropriately applied to the second to third embodiments.

As shown in FIG. 4, the transparent conductive film 1 of the second embodiment includes a transparent base material 2, a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in order from the bottom, and a transparent conductive film. The layer 5 comprises an Hf region 8 and a Sn region 6 arranged above it. Preferably, the transparent conductive layer 5 has the Hf region 8, the Sn/Hf mixed region 7, and the Sn region 6 in order from the lower side.

By crystallizing the transparent conductive film 1 of the second embodiment by heating, the crystalline transparent conductive film of the second embodiment is obtained. As shown in FIG. 2, this crystalline transparent conductive film includes a crystalline transparent conductive layer 5A having an Hf region 8A, a Sn/Hf mixed region 7A, and a Sn region 6A in order from the bottom.

As shown in FIG. 5, the transparent conductive film 1 of the third embodiment includes a transparent base material 2, a hard coat layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in order from the bottom, and a transparent conductive film. The layer 5 includes an Hf region 8, an Sn region 6 arranged above the Hf region 8, and an Hf region 8 arranged above the Sn region 6. Preferably, the transparent conductive layer 5 has the Hf region 8, the Sn/Hf mixed region 7, the Sn region 6, the Sn/Hf mixed region 7, and the Hf region 8 in order from the lower side.

The crystalline transparent conductive film of the third embodiment is obtained by crystallizing the transparent conductive film 1 of the third embodiment by heating. In this crystalline transparent conductive film, as shown in FIG. 2, the Hf region 8A, the Sn/Hf mixed region 7A, the Sn region 6A, the Sn/Hf mixed region 7A, and the Hf region 8A are sequentially arranged from the lower side. It has a crystalline transparent conductive layer 5A.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. Further, the compounding ratios (content ratios) used in the following description, specific numerical values such as physical property values, parameters, etc. are described in the above “Modes for carrying out the invention”, and the corresponding compounding ratios ( Substitute the upper limit (value defined as "below" or "less than") or the lower limit (value defined as "greater than or equal to" "excess") such as content ratio), physical property value, parameter etc. be able to.

Example 1
As a transparent substrate, a cycloolefin film (22 μm in thickness, manufactured by Nippon Zeon Co., Ltd., “Zeonor film”) was prepared.

A hard coat composition solution containing an ultraviolet curable acrylic resin was applied and dried on the upper surface of the transparent substrate. Then, the hard coat composition was cured by ultraviolet irradiation. As a result, a hard coat layer having a thickness of 1.0 μm was formed.

Then, an optical adjustment composition solution containing an ultraviolet curable acrylic resin and zirconium oxide particles was applied to the upper surface of the hard coat layer and dried on the upper surface of the hard coat layer. Thereafter, the optical adjustment composition was cured by irradiation with ultraviolet rays. Thereby, an optical adjustment layer having a thickness of 80 nm and a refractive index of 1.64 was formed.

Then, a transparent conductive layer was formed on the upper surface of the optical adjustment layer.

Specifically, the ITO sintered body (containing 90 wt% indium oxide and 10 wt% tin oxide) was sputtered by adjusting the setting thickness of the sputter output to 21 nm by the DC sputtering method. As the vacuum condition, 98% of argon gas and 2% of oxygen gas were introduced, and the atmospheric pressure was 0.4 Pa. Thereby, an amorphous ITO layer was formed.

Then, the In—Hf—Ta-containing oxide sintered body (manufactured by Tosoh Corporation, trade name “USR”) was sputtered on the upper surface of the ITO layer by a DC sputtering method to adjust the setting thickness of the sputter output to 10 nm. .. As the vacuum condition, 98% of argon gas and 2% of oxygen gas were introduced, and the atmospheric pressure was 0.4 Pa. As a result, an amorphous In-Hf-Ta-containing oxide layer was formed.

Thus, a transparent conductive film composed of the transparent substrate/hard coat layer/optical adjustment layer/transparent conductive layer was produced.

Example 2
A transparent conductive film was produced in the same manner as in Example 1 except that the set thickness of each layer of the transparent conductive layer was changed to the thickness described in Table 1.

Comparative Example 1
In the transparent conductive layer, first, the set thickness was changed to 28 nm, and an ITO sintered body (containing 90 wt% indium oxide and 10 wt% tin oxide) was sputtered to form a first ITO layer (lower layer). Next, the set thickness was changed to 3 nm, and an ITO sintered body (containing 97 wt% indium oxide and 3 wt% tin oxide) was sputtered to form a second ITO layer (upper layer). In addition, the In-Hf-Ta-containing oxide layer was not formed. A transparent conductive film was produced in the same manner as in Example 1 except these.

Comparative Examples 2-3
A transparent conductive film was produced in the same manner as in Comparative Example 1 except that the set thickness of each layer of the transparent conductive layer was changed to the thickness described in Table 1.

Comparative Example 4
In the transparent conductive layer, the set thickness was adjusted to 26 nm to form an In-Hf-Ta-containing oxide layer. Moreover, the ITO layer was not formed. A transparent conductive film was produced in the same manner as in Example 1 except for these.

(Measurement of film thickness of transparent conductive layer)
The thickness of each transparent conductive layer was measured by observing the cross section of each of the transparent conductive films of Examples and Comparative Examples using a transmission electron microscope (TEM). The results are shown in Table 1.

(Measurement of element ratio of transparent conductive layer)
Surface elemental analysis was performed on the transparent conductive films of Examples and Comparative Examples by X-ray photoelectron spectroscopy (ESCA). Specifically, the transparent conductive layer was qualitatively analyzed by wide scanning. After that, depth direction analysis by Ar ion etching was performed on each of In, Hf, O, and C elements to calculate their atomic concentrations (atomic %). The measurement conditions were as follows.

Device: ULVAC-PHI, "Quantum 2000"
X-ray source: Monochrome Al Kα
X-ray setting: 100 μmφ (15 kV, 25 W)
Photoelectron extraction angle: 45 degrees Neutralization condition: Neutralization gun and Ar ion gun (neutralization mode) used together Ar ion gun acceleration voltage: 1 kV
Raster size of Ar ion gun: 2mm×2mm
Etching rate of Ar ion gun: about 2 nm/min in terms of SiO ₂ The graph in Example 1 at this time is shown in FIG. As is apparent from FIG. 6, the transparent conductive layer of Example 1 has Hf regions, Sn/Hf mixed regions, and Sn regions formed in this order from the upper surface to the lower surface.

(Measurement of conductivity)
The transparent conductive films of Examples and Comparative Examples were completely crystallized by heating at 100° C. for 60 minutes to obtain crystalline transparent conductive films. The surface resistivity and the specific resistance of the crystalline transparent conductive layer of the crystalline transparent conductive film were measured at 15 mm intervals by the 4-terminal method. The results are shown in Table 1.

(Measurement of crystallization rate)
The transparent conductive films of Examples and Comparative Examples were heated at 100° C. for a predetermined time (15 minutes, 30 minutes and 60 minutes), and the crystallization rate at each time was measured. The results are shown in Fig. 7.

The crystallization rate was calculated by the following formula.
Crystallization rate (%)=(Rs−Ri)/(Rf−Ri)×100
Rs is the surface resistivity immediately after heating at each time (Ω/□), Ri is the surface resistivity before heating (Ω/□), Rf is the surface resistivity after complete crystallization (Ω/□). □).

1 Transparent Conductive Film 1A Crystalline Transparent Conductive Film 2 Transparent Substrate 5 Transparent Conductive Layer 5A Crystalline Transparent Conductive Layer 6 Sn Region 7 Sn/Hf Mixed Region 8 Hf Region

Claims (5)

A transparent substrate and a transparent conductive layer arranged on one side in the thickness direction of the transparent substrate,
The transparent conductive layer is amorphous,
The transparent conductive film, wherein the transparent conductive layer has an Hf region made of an indium oxide containing hafnium and a Sn region made of an indium oxide containing tin in the thickness direction. The transparent conductive film according to claim 1, wherein the Hf region is arranged on one side in the thickness direction of the Sn region. The thickness of the said transparent conductive layer is 10 nm or more and 35 nm or less, The transparent conductive film of Claim 1 or 2 characterized by the above-mentioned. The transparent conductive film according to claim 1, wherein the transparent base material is a cycloolefin film. A crystalline transparent conductive film obtained by crystallizing the transparent conductive layer of the transparent conductive film according to any one of claims 1 to 4.

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