WO2023112716A1

WO2023112716A1 - Transparent conductive film

Info

Publication number: WO2023112716A1
Application number: PCT/JP2022/044522
Authority: WO
Inventors: 那由太嶋田; 徹奥西; 明日美佐野
Original assignee: 尾池工業株式会社
Priority date: 2021-12-15
Filing date: 2022-12-02
Publication date: 2023-06-22

Abstract

The present invention provides a transparent conductive film which sequentially comprises a base material, a first metal oxide layer, a metal layer and a second metal oxide layer in this order, wherein: the first metal oxide layer contains zinc oxide and tin oxide; the metal layer contains at least one of silver and a silver alloy; the second metal oxide layer contains indium oxide and tin oxide; and a peak in not detected at 2θ = 29° to 32° as measured by X-ray crystal diffractometry after subjecting the transparent conductive film to a heat treatment at 150°C for 30 minutes.

Description

transparent conductive film

The present invention relates to transparent conductive films.

At present, transparent conductive films are used in various products such as touch panels, electronic paper, liquid crystal displays, and RF-ID tags.
As a transparent conductive film, there is a thin film of ITO made of indium oxide and tin oxide. High conductivity is required.

In order to obtain high conductivity in a thin ITO film, in addition to optimizing the carrier density and mobility, the film thickness is required to be several times that used in small touch panels and the like. However, when the film thickness is increased, the ITO thin film is easily cracked, and the flexibility is impaired. Moreover, an increase in cost due to an increase in processing time cannot be avoided.
Therefore, in order to develop high conductivity, a transparent electrode using a silver alloy with a low specific resistance is formed by laminating a metal oxide, a silver alloy, and a thin layer of a metal oxide in this order (metal oxide/silver alloy/ metal oxides) have been proposed (see, for example, Patent Document 1).
In this transparent electrode, by using a silver alloy whose carrier density is one order of magnitude higher than that of ITO, the average thickness of the laminate of metal oxide/silver alloy/metal oxide can be reduced while obtaining high conductivity. It reduces manufacturing costs while improving performance.

JP-A-2002-15623

However, in the technique disclosed in Patent Document 1, in an electrode having a laminated structure of metal oxide/silver alloy/metal oxide, the silver alloy is sandwiched between the same metal oxide such as ITO, and the metal oxide is transparent. There is a problem that silver in the silver alloy tends to agglomerate due to the water vapor and the like, and the resistance to moist heat may be lowered.
In addition, aggregation of silver deteriorates the appearance and makes it difficult to use for display applications. In addition, there is a problem that the photoelectric conversion efficiency may be lowered in solar cells and the like.
Due to these problems, it is very important to suppress aggregation of silver.

The object of the present invention is to solve the above-mentioned problems in the past and to achieve the following objects. That is, an object of the present invention is to provide a transparent conductive film which is excellent in conductivity and resistance to moist heat.

Means for solving the above problems are as follows. Namely
<1> A transparent conductive film having a substrate, a first metal oxide layer, a metal layer, and a second metal oxide layer in this order,
The first metal oxide layer contains zinc oxide and tin oxide,
the metal layer contains at least one of silver and a silver alloy,
The second metal oxide layer contains indium oxide and tin oxide,
A transparent conductive film characterized in that no peak is detected at 2θ = 29 ° to 32 ° when the transparent conductive film is heat-treated at 150 ° C. for 30 minutes and then measured by X-ray crystal diffraction. be.
<2> The transparent conductive film according to <1>, wherein the second metal oxide layer has an arithmetic mean roughness Ra of 15 nm or less.
<3> The content of tin oxide in the second metal oxide layer is 5% by mass or more with respect to the total amount of the indium oxide and the tin oxide. It is a transparent conductive film.
<4> The transparent conductive film according to any one of <1> to <3>, having a total light transmittance of 82% or more as measured according to JIS K7361-1.

According to the present invention, it is possible to solve the above-mentioned conventional problems, achieve the above-mentioned objects, and provide a transparent conductive film excellent in conductivity and resistance to moist heat.

FIG. 1A is a cross-sectional view showing an example of the transparent conductive film of the present invention. FIG. 1B is a cross-sectional view showing another example of the transparent conductive film of the present invention. 2A is a diagram showing the measurement results of the transparent conductive film of Example 1 by the X-ray crystal diffraction method. FIG. 2B is a diagram showing the measurement results of the transparent conductive film of Example 2 by the X-ray crystal diffraction method. FIG. 2C is a diagram showing the results of X-ray crystal diffraction measurement of the transparent conductive film of Example 3. FIG. 2D is a diagram showing the measurement results of the transparent conductive film of Comparative Example 1 by the X-ray crystal diffraction method. FIG. 2E is a diagram showing measurement results of the transparent conductive film of Comparative Example 2 by the X-ray crystal diffraction method. FIG. 2F is a diagram showing the measurement results of the transparent conductive film of Comparative Example 3 by the X-ray crystal diffraction method. FIG. 2G is a diagram showing the measurement results of the transparent conductive film of Comparative Example 4 by the X-ray crystal diffraction method. FIG. 2H is a diagram showing the measurement results of the transparent conductive film of Comparative Example 5 by the X-ray crystal diffraction method. FIG. 2I is a diagram showing the measurement results of the transparent conductive film of Comparative Example 6 by the X-ray crystal diffraction method. FIG. 2J is a diagram showing the measurement results of the transparent conductive film of Comparative Example 7 by the X-ray crystal diffraction method. FIG. 2K is a diagram showing the measurement results of the transparent conductive film of Comparative Example 8 by the X-ray crystal diffraction method. FIG. 2L is a diagram showing the measurement results of the transparent conductive film of Comparative Example 9 by the X-ray crystal diffraction method. FIG. 2M is a diagram showing the measurement results of the transparent conductive film of Comparative Example 10 by the X-ray crystal diffraction method. FIG. 2N is a diagram showing the measurement results of the transparent conductive film of Comparative Example 11 by the X-ray crystal diffraction method. FIG. 2O is a diagram showing the measurement results of the transparent conductive film of Comparative Example 12 by the X-ray crystal diffraction method. FIG. 2P is a diagram showing the measurement results of the transparent conductive film of Example 4 by the X-ray crystal diffraction method. FIG. 2Q is a diagram showing the measurement results of the transparent conductive film of Example 5 by the X-ray crystal diffraction method. FIG. 3A is a photograph showing the appearance of the transparent conductive film of Example 1 after a heat and humidity resistance test (60° C., 95% RH, 250 hours). 3B is a photograph showing the appearance of the transparent conductive film of Example 1 after a heat and humidity resistance test (80° C., 85% RH, 250 hours). 3C is a photograph showing the appearance of the transparent conductive film of Comparative Example 5 after a heat and humidity resistance test (60° C., 95% RH, 250 hours). 3D is a photograph showing the appearance of the transparent conductive film of Comparative Example 5 after a heat and humidity resistance test (80° C., 85% RH, 250 hours).

(transparent conductive film)
The transparent conductive film of the present invention has a substrate, a first metal oxide layer, a metal layer, and a second metal oxide layer in this order,
The first metal oxide layer contains zinc oxide and tin oxide,
the metal layer contains at least one of silver and a silver alloy,
The second metal oxide layer contains indium oxide and tin oxide, and further has other layers as necessary.
In the transparent conductive film of the present invention, no peak at 2θ = 29° to 32° is detected when measured by X-ray crystal diffraction after heat-treating the transparent conductive film at 150°C for 30 minutes.

In a transparent conductive film having a laminated structure having a substrate, a first metal oxide layer, a metal layer, and a second metal oxide layer in this order, the second metal oxide layer is exposed. Therefore, in order to improve the conductivity of the transparent conductive film, it is desirable that the conductivity (surface resistance) itself of the second metal oxide layer is good.
Further, depending on the use of the transparent conductive film, heat treatment may be required in the post-treatment. In this case, the materials of the first and second metal oxide layers are crystallized by the heat treatment to generate grain boundaries, thereby creating passages for outside air containing water vapor in the first and second metal oxide layers. The water vapor may cause silver agglomeration in the metal layer. For this reason, the present inventors have found that it is important for the first and second metal oxide layers to have the property of being able to maintain an amorphous state over time or even after heat treatment. .

The present inventors have found that a transparent conductive film having a laminated structure having a substrate, a first metal oxide layer, a metal layer, and a second metal oxide layer in this order, wherein the metal layer comprises silver and It was found that by containing at least one of the silver alloys and containing indium oxide and tin oxide in the second metal oxide layer, it is possible to achieve both excellent electrical conductivity and resistance to moist heat.
In particular, (1) by combining a metal layer with a high carrier concentration and a second metal oxide layer with a low surface resistance, excellent conductivity can be exhibited, and (2-1) the surface resistance of itself (2-2) disposing a first metal oxide layer containing zinc oxide and tin oxide that is difficult to crystallize on the substrate side, and (2-2) forming a second metal oxide layer in an amorphous state; The present inventors have found that by arranging the first and second metal oxide layers, it is possible to exhibit excellent moist heat resistance (barrier function) based on the amorphous state in the first and second metal oxide layers.
In addition, regarding the second metal oxide layer containing indium oxide and tin oxide, the phrase “can maintain an amorphous state over time or even after heat treatment” means that After heat treatment (acceleration test), it is confirmed by X-ray crystal diffraction whether a peak appears at 2θ = 29 ° to 32 ° corresponding to the (222) plane of ITO in the second metal oxide layer. can do. When a peak appears at 2θ=29° to 32°, it means that the film is crystallized by the accelerated test, and it can be judged that the film has a property (film quality) that tends to crystallize over time. Conversely, if there is no peak at 2θ = 29° to 32°, it means that crystallization has not occurred even in the accelerated test, and it can be judged that the film has a property (film quality) that is difficult to crystallize over time. can.

The absence of a peak at 2θ = 29° to 32° corresponding to the (222) plane of ITO in the second metal oxide layer containing indium oxide and tin oxide is based on the measurement results of the X-ray crystal diffraction method. can judge.
Specifically, it can be confirmed by the following method.
First, an X-ray crystal diffraction method is performed under the following conditions.
<Measurement conditions for the X-ray crystal diffraction method>
・ Device name: X-ray crystal diffraction device (XRD6100, manufactured by Shimadzu Corporation)
・Standard mode ・X-ray source: CuKα
・Tube voltage: 40 kV
・Tube current: 30mA
・Drive shaft: 2θ/θ
・Scanning speed: 2.00°/min
・Scanning step: 0.02°
・Scanning range: Measure diffraction intensity from 29° to 32° ・Goniometer: vertical type ・Divergence slit: 1°
・Scattering slit: 1°
・Receiving slit: 0.30mm
Next, the following values <1> to <3> are calculated based on the measured raw data.
<1> Maximum value of diffraction intensity in the range of 30° to 31° <2> Value obtained by adding diffraction intensity at 29° and 32° and dividing by 2 <3> Value obtained by dividing <1> by <2><1> Maximum value of diffraction intensity in the range of 30° to 31°” is higher when the ITO in the second metal oxide layer is crystallized than when the ITO is not crystallized. .
Further, "<1> the maximum value of the diffraction intensity in the range of 30° to 31°" is "<2> the diffraction intensity at 29° and 32° when the ITO in the second metal oxide layer is not crystallized. is added and divided by 2".
Therefore, in the present invention, when "the value obtained by dividing <3><1> by <2>" is 1.2 or more, it is determined that "the peak is detected", and "<3>< When the value obtained by dividing 1> by <2> is less than 1.2, it is determined that 'no peak is detected'.

In the present invention, "transparent" means that the haze value measured according to JIS K7136 is 15% or less. The haze value of the transparent conductive film of the present invention measured according to JIS K7136 is preferably 6% or less, more preferably 4% or less, and even more preferably 2% or less. When the haze value is 6% or less, it can be suitably used for displays and the like.
In the transparent conductive film of the present invention, the total light transmittance (visible light transmittance) measured according to JIS K7361-1 is preferably 78% or more, more preferably 80% or more, and further 82% or more. preferable. When the total light transmittance is 78% or more, a transparent conductive film with excellent transparency can be obtained, and it can be suitably used for applications requiring high visible light transmittance, such as displays and solar cells.
The haze value and the total light transmittance are not particularly limited and can be appropriately selected according to the purpose. can do.

The surface resistance value of the transparent conductive film of the present invention is preferably 30Ω/□ or less, more preferably 20Ω/□ or less, and even more preferably 15Ω/□ or less.
Examples of the method for measuring the surface resistance value include a method of measuring arbitrary 10 points with a low resistivity meter (manufactured by Mitsubishi Chemical Analytech, model number: MCP-T610) and calculating the average value. .

<Base material>
The substrate is a material that serves as the substrate of the transparent conductive film of the present invention.

The shape, structure, and size of the base material are not particularly limited, and can be appropriately selected according to the purpose.

The material of the base material is not particularly limited and can be appropriately selected depending on the intended purpose. , polyethylene-2,6-naphthalate (PEN), cycloolefin polymer (COP), triacetylcellulose (TAC), polyetheretherketone (PEEK), liquid crystal polymer (LCP), transparent polyimide (CPI), and the like.

The average thickness of the substrate is preferably 6 μm or more and 300 μm or less, more preferably 12 μm or more and 250 μm or less, and even more preferably 25 μm or more and 200 μm or less. When the average thickness of the base material is 6 μm or more, the handleability during processing can be improved. Moreover, when the average thickness of the substrate is 300 μm or less, a flexible transparent conductive film can be obtained.
The average thickness of the base material can be obtained by measuring the thickness at arbitrary five points using an electronic micrometer (manufactured by Anritsu Co., Ltd., device name: KG3001A) and calculating the average value.

The total light transmittance of the substrate measured according to JIS K7361-1 is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. When the total light transmittance is 60% or more, the transparency of the transparent conductive film can be improved.
The total light transmittance is not particularly limited and can be appropriately selected according to the purpose.

Further, in the substrate, the haze value measured according to JIS K7136 is preferably 6% or less, more preferably 4% or less, and even more preferably 2% or less. The transparency in a transparent conductive film can be improved as the said haze value is 6 % or less. Moreover, when the haze value is 2% or less, the transparent conductive film of the present invention can be suitably used for displays.
The haze value is not particularly limited and can be appropriately selected depending on the intended purpose.

Other properties of the base material include, for example, smoothness.

An index of the smoothness of the base material includes, for example, the arithmetic mean roughness Ra of the surface of the base material.
The arithmetic mean roughness Ra of the substrate surface is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less. When the arithmetic mean roughness Ra of the surface of the substrate is 50 nm or less, the occurrence of defects (gaps due to surface unevenness) in the first metal oxide layer and the second metal oxide layer described later is suppressed, and silver It is possible to suppress the intrusion of water vapor that causes aggregation of the
The arithmetic mean roughness Ra of the surface of the base material can be measured, for example, by an optical interference type surface roughness meter (WYKO Contour GT K1M manufactured by Bruker Japan, measurement conditions: VSI mode).

<First metal oxide layer>
The first metal oxide layer is arranged between the base material and a metal layer to be described later.

The shape, structure, and size of the first metal oxide layer are not particularly limited, and can be appropriately selected according to the purpose.

The material of the first metal oxide layer contains zinc oxide and tin oxide, and further contains other components as necessary. When the first metal oxide layer contains zinc oxide and tin oxide, it is possible to obtain a film that is amorphous and has no crystal grain boundaries, and is permeable to water vapor that causes aggregation of silver contained in the metal layer. can be made difficult.
Examples of the zinc oxide and tin oxide include ZTO.

The content of tin oxide in the zinc oxide and tin oxide is preferably 15% by mass or more and 65% by mass or less, more preferably 20% by mass or more and 60% by mass or less, based on the total amount of zinc oxide and tin oxide. % by mass or more and 55% by mass or less is more preferable. A favorable amorphous film (layer) can be obtained when the content of tin oxide in the zinc oxide and tin oxide is 15% by mass or more with respect to the total amount of zinc oxide and tin oxide. Further, when the content of tin oxide in the zinc oxide and tin oxide is 65% by mass or less with respect to the total amount of zinc oxide and tin oxide, the moist heat resistance of the first metal oxide layer can be improved. can.

The content of zinc oxide and tin oxide in the first metal oxide layer is preferably 90% by mass or more, more preferably 95% by mass or more, relative to the total amount of the first metal oxide layer. When the content of zinc oxide and tin oxide in the first metal oxide layer is 90% by mass or more, the total light transmittance can be improved.

The other components are not particularly limited, and may contain components other than zinc oxide and tin oxide as appropriate as long as the effects of the present invention are not impaired.

The average thickness of the first metal oxide layer is preferably 25 nm or more and 65 nm or less, more preferably 35 nm or more and 63 nm or less, and even more preferably 40 nm or more and 60 nm or less. When the average thickness of the first metal oxide layer is 25 nm or more, the effect of suppressing the permeation of water vapor can be improved. Further, when the average thickness of the first metal oxide layer is 65 nm or less, the total light transmittance can be increased.
The average thickness (height) of the first metal oxide layer can be measured as follows.
First, a substrate on which a first metal oxide layer having a plurality of levels of predetermined thickness is formed is prepared, and the physical thickness of the first metal oxide layer having a plurality of levels of predetermined thickness is measured using a contact-type profilometer. Measured by Further, the amount of the material of the first metal oxide layer in the first metal oxide layer having a predetermined thickness at multiple levels was quantitatively analyzed using a fluorescent X-ray measurement device (XRF, manufactured by Rigaku Co., Ltd.). Measure. A calibration curve is prepared from the film thickness measured by the contact profilometer and the amount of material of the first metal oxide layer measured by quantitative analysis using an X-ray fluorescence spectrometer (XRF). In a sample to be actually measured, the amount of the material of the first metal oxide layer is quantitatively analyzed using an X-ray fluorescence spectrometer (XRF), and the film thickness is calculated using the prepared calibration curve. Ten samples are prepared in the same manner, and the average value is taken as the average thickness.

The method for forming the first metal oxide layer is not particularly limited and can be appropriately selected depending on the intended purpose. and a method of treating the entire surface of the substrate using a method or the like.

<Metal layer>
The metal layer is arranged between the first metal oxide layer and a second metal oxide layer to be described later.

The shape, structure, and size of the metal layer are not particularly limited and can be appropriately selected according to the purpose.

The material of the metal layer contains at least one of silver and a silver alloy, and further contains other components as necessary.
The metal layer preferably contains a silver alloy. By containing a silver alloy in the metal layer, the effect of suppressing aggregation of silver can be improved.
The metal layer may contain silver as a main component, and the content of silver in the metal layer is preferably 80% by mass or more and 99.9% by mass or less, and more preferably 82% by mass or more and 99.8% by mass. % or less, and more preferably 85% by mass or more and 99.7% by mass or less.
The silver alloy may contain silver as a main component, and the content of silver in the silver alloy is preferably 80% by mass or more and 99.9% by mass or less, and more preferably 82% by mass or more and 99.8% by mass. % or less, and more preferably 85% by mass or more and 99.7% by mass or less. When the content of silver in the silver alloy is 80% by mass or more, electrical conductivity and optical properties can be improved. When the silver content is 99.9% by mass or less, it is possible to suppress migration and inhibit aggregation of silver more than silver alone.
Examples of the silver alloys include silver-copper alloys.

The other components are not particularly limited as long as they do not inhibit the effects of the present invention. Examples include Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, Rh, Ir. , Ni, Pd, Pt, Cu, Au, Zn, Al, Ga, In, Si, Ge, Sn, Bi, Mn, C, B, N, P, S and the like.

The average thickness of the metal layer is preferably 4 nm or more and 16 nm or less, more preferably 5 nm or more and 14 nm or less, and even more preferably 6 nm or more and 12 nm or less. Electrical conductivity can be improved as the average thickness of the said metal layer is 4 nm or more. Further, when the average thickness of the metal layer is 16 nm or less, the total light transmittance can be enhanced.
The average thickness (height) of the metal layer can be measured, for example, as follows.
First, a substrate on which a plurality of levels of predetermined thickness metal layers are formed is prepared, and the physical film thickness of the plurality of levels of predetermined thicknesses of the metal layer is measured by a contact profilometer. In addition, the amount of metal layer material in a plurality of levels of predetermined thickness of the metal layer is measured by quantitative analysis using a fluorescent X-ray measurement device (XRF, manufactured by Rigaku Corporation). A calibration curve is prepared from the film thickness measured by the contact profilometer and the material amount of the metal layer measured by quantitative analysis using an X-ray fluorescence spectrometer (XRF). In a sample to be actually measured, the amount of material of the metal layer is quantitatively analyzed using an X-ray fluorescence spectrometer (XRF), and the film thickness is calculated using the prepared calibration curve. Ten samples are prepared in the same manner, and the average value is taken as the average thickness.

The method for forming the metal layer is not particularly limited and can be appropriately selected according to the purpose. and a method of treating the entire exposed surface of the first metal oxide layer.

<Second metal oxide layer>
The second metal oxide layer is a layer arranged on the metal layer.

The shape, structure, and size of the second metal oxide layer are not particularly limited, and can be appropriately selected according to the purpose.

The material of the second metal oxide layer contains indium oxide and tin oxide, and further contains other components as necessary. The conductivity of the second metal oxide layer can be improved by containing the indium oxide and tin oxide.
Examples of the indium oxide and tin oxide include ITO.

The content of tin oxide in the indium oxide and tin oxide is preferably 5% by mass or more, more preferably 5% by mass or more and 14% by mass or less, and 7% by mass or more, based on the total amount of indium oxide and tin oxide. 12% by mass or less is more preferable, and 8% by mass or more and 11% by mass or less is most preferable. When the content of tin oxide in the indium oxide and tin oxide is 5% by mass or more, the effect of suppressing crystallization can be improved, and the conductivity and resistance to moist heat can be improved.
Further, when the content of tin oxide in the indium oxide and tin oxide is 14% by mass or less, excellent total light transmittance can be obtained.

The content of indium oxide and tin oxide in the second metal oxide layer is preferably 95% by mass or more, more preferably 98% by mass or more, relative to the total amount of the second metal oxide layer.

The other components are not particularly limited, and may contain components other than the indium oxide and tin oxide as appropriate as long as the effects of the present invention are not hindered.

The average thickness of the second metal oxide layer is preferably 30 nm or more and 60 nm or less, more preferably 32 nm or more and 55 nm or less, and even more preferably 35 nm or more and 50 nm or less. When the average thickness of the second metal oxide layer is 30 nm or more, the effect of suppressing the permeation of water vapor can be improved. Further, when the average thickness of the second metal oxide layer is 60 nm or less, the total light transmittance can be increased.
The average thickness (height) of the second metal oxide layer can be measured, for example, as follows.
First, a substrate on which a second metal oxide layer having a plurality of levels of predetermined thickness is formed is prepared, and the physical thickness of the second metal oxide layer having a plurality of levels of predetermined thickness is measured by a contact profilometer. Measure. In addition, the amount of the material of the second metal oxide layer in the second metal oxide layer having a predetermined thickness at multiple levels was quantitatively analyzed using a fluorescent X-ray measurement device (XRF, manufactured by Rigaku Co., Ltd.). Measure. A calibration curve is prepared from the film thickness measured by the contact profilometer and the amount of the material of the second metal oxide layer measured by quantitative analysis using an X-ray fluorescence spectrometer (XRF). In a sample to be actually measured, the amount of the material of the second metal oxide layer is quantitatively analyzed using an X-ray fluorescence spectrometer (XRF), and the film thickness is calculated using the prepared calibration curve. Ten samples are prepared in the same manner, and the average value is taken as the average thickness.

The arithmetic mean roughness Ra of the surface of the second metal oxide layer is preferably 15 nm or less, more preferably 11 nm or less, and even more preferably 10 nm or less. When the arithmetic mean roughness Ra of the surface of the second metal oxide layer is 15 nm or less, moist heat resistance can be improved.
The arithmetic mean roughness Ra of the surface of the second metal oxide layer can be measured by a light interference type surface roughness meter (WYKO Contour GT K1M manufactured by Bruker Japan, measurement conditions: VSI mode).
The surface of the second metal oxide layer means the surface of the second metal oxide layer that is not the side facing the metal layer.

The surface resistance value of only the second metal oxide layer is preferably 10,000 Ω/square or less, more preferably 5,000 Ω/square or less, and even more preferably 1,000 Ω/square or less.
As a method for measuring the surface resistance value, for example, only the second metal oxide layer is formed on the substrate, and an arbitrary 10 For example, a method of measuring points and calculating the average value thereof can be used.

The method for forming the second metal oxide layer is not particularly limited and can be appropriately selected according to the purpose. For example, the entire exposed surface of the metal layer is treated using a method or the like.
When forming the second metal oxide layer, it is preferable to contain hydrogen in the reaction atmosphere during layer formation in order to prevent the layer (film) from crystallizing over time. By containing hydrogen in the reaction atmosphere, it is possible to obtain a film (layer) in which the second metal oxide layer can maintain an amorphous state even when heat is applied, and a transparent conductive film having excellent moist heat resistance. can be obtained.

<Other layers>
The other layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include an underlayer.

<<Underlayer>>
The underlying layer is a layer arranged between the substrate and the first metal oxide layer. By providing the base layer, it is possible to obtain effects such as improvement in adhesion between the base material and the first metal oxide layer and improvement in scratch resistance.

The shape, structure, and size of the underlying layer are not particularly limited, and can be appropriately selected according to the purpose.

Examples of materials for the base layer include acrylic resins, ester resins, silicone resins, and organic-inorganic hybrid materials.

The average thickness of the underlayer is preferably 50 nm or more and 3,500 nm or less, more preferably 70 nm or more and 3,000 nm or less, and even more preferably 80 nm or more and 2,500 nm or less. When the average thickness of the underlayer is 50 nm or more, the adhesion between the substrate and the first metal oxide layer can be improved. When the average thickness of the underlayer is 3,500 nm or less, the total light transmittance can be increased.
The average thickness (height) of the underlying layer can be measured, for example, as follows.
The reflected waveform of the substrate on which the underlayer is formed is measured using an ultraviolet-visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation), and the average thickness (height) of the underlayer is calculated from the spectrum shape. be able to.

The arithmetic surface roughness Ra of the surface of the underlayer is not particularly limited and can be appropriately selected according to the purpose, but the smaller the better. The smaller the arithmetic surface roughness Ra of the surface of the underlayer, the higher the arithmetic mean roughness of the surfaces of the first metal oxide layer, the metal layer, and the second metal oxide layer formed on the underlayer. The height Ra can be reduced.

The method for forming the base layer is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a method of treating the entire surface of the base material using wet coating or the like.

Here, one example of the transparent conductive film of the present invention will be described with reference to the drawings.
FIG. 1A is a cross-sectional view showing an example of the transparent conductive film of the present invention. FIG. 1B is a cross-sectional view showing another example of the transparent conductive film of the present invention.
The transparent conductive film 10 shown in FIG. 1A has a first metal oxide layer 12a, a metal layer 13, and a second metal oxide layer 12b on a substrate 11 in this order.
The transparent conductive film 10 shown in FIG. 1B is the transparent conductive film 10 shown in FIG. It is the same as the transparent conductive film 10 shown.

Applications of the transparent conductive film of the present invention include, for example, liquid crystal displays, organic EL, inorganic EL lighting, thin film solar cells, electromagnetic wave shields, window films, electronic blackboards, and transparent electrodes such as transparent heaters.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
<Production of Transparent Conductive Film 1>
NH-1000G (organic-inorganic hybrid resin, manufactured by Nippon Soda Co., Ltd.) was coated on a polyethylene terephthalate film with an average thickness of 125 μm as a base material by a wet coating method to form a base layer with an average thickness of 1.5 μm. .
Next, on the underlayer, the pressure during film formation was adjusted to 0.37 Pa and the input power density was adjusted to 3.3 W/cm ² , and under the introduction of argon gas and oxygen gas (argon:oxygen = 95:5), zinc oxide was applied. ZTO containing 70% by mass of and 30% by mass of tin oxide was sputtered to form a first metal oxide layer having an average thickness of 53 nm.
Next, on the first metal oxide layer, the pressure during film formation was adjusted to 0.25 Pa and the input power density was adjusted to 1.5 W/cm ² , and under the introduction of argon gas, 89% by mass of silver and 11% of copper were added. A silver alloy containing 1% by mass was sputtered to form a metal layer with an average thickness of 11 nm.
Next, on the metal layer, the pressure during film formation was adjusted to 0.35 Pa and the input power density was adjusted to 3.3 W/cm ² , and under the introduction of argon gas, oxygen gas, and hydrogen gas (argon:oxygen:hydrogen=95. 5:3.5:1), ITO containing 90% by mass of indium oxide and 10% by mass of tin oxide was sputtered to form a second metal oxide layer with an average thickness of 38 nm, and a transparent conductive film 1 was formed. Obtained.

(Example 2)
<Production of Transparent Conductive Film 2>
In Example 1, the same as Example 1 except that the material of the underlayer was changed to Si Coat 801 (silicone resin, manufactured by Momentive Performance Materials Japan LLC) to form an underlayer with an average thickness of 90 nm. Then, a transparent conductive film 2 was obtained.

(Example 3)
<Production of transparent conductive film 3>
In Example 1, in the same manner as in Example 1, except that the material of the underlayer was changed to NSC-3162A (silicone resin, manufactured by Nippon Fine Chemical Co., Ltd.) and an underlayer with an average thickness of 1.5 μm was formed. A transparent conductive film 3 was obtained.

(Example 4)
<Production of Transparent Conductive Film 4>
Example 1 except that "ITO containing 90% by mass of indium oxide and 10% by mass of tin oxide" in Example 1 was changed to "ITO containing 95% by mass of indium oxide and 5% by mass of tin oxide". A transparent conductive film 4 was obtained in the same manner.

(Example 5)
<Production of Transparent Conductive Film 5>
Example 2 except that "ITO containing 90% by mass of indium oxide and 10% by mass of tin oxide" in Example 2 was changed to "ITO containing 95% by mass of indium oxide and 5% by mass of tin oxide". A transparent conductive film 5 was obtained in the same manner as above.

(Comparative example 1)
<Production of Transparent Conductive Film 6>
In Example 1, the conditions for forming the second metal oxide layer were adjusted to a film-forming pressure of 0.37 Pa and an input power density of 3.3 W/cm ² under the introduction of argon gas and oxygen gas (argon: oxygen = A transparent conductive film 6 was obtained in the same manner as in Example 1, except that the ratio was changed to 98:2).

(Comparative example 2)
<Production of Transparent Conductive Film 7>
A transparent conductive film 7 was obtained in the same manner as in Example 2, except that the conditions for forming the second metal oxide layer were changed to the same conditions as in Comparative Example 1.

(Comparative Example 3)
<Production of transparent conductive film 8>
A transparent conductive film 8 was obtained in the same manner as in Example 3, except that the conditions for forming the second metal oxide layer were changed to the same conditions as in Comparative Example 1.

(Comparative Example 4)
<Production of Transparent Conductive Film 9>
In Example 1, the conditions for forming the first metal oxide layer and the conditions for forming the second metal oxide layer were adjusted to a film-forming pressure of 0.37 Pa and an input power density of 3.3 W/cm ² . , Under the introduction of argon gas and oxygen gas (argon: oxygen = 98: 2), ITO containing 90% by mass of indium oxide and 10% by mass of tin oxide was sputtered, and the average thickness was changed to 43 nm. A transparent conductive film 9 was obtained in the same manner as in Example 1.

(Comparative Example 5)
<Production of transparent conductive film 10>
In Example 2, the same procedure as in Example 2 was performed except that the conditions for forming the first metal oxide layer and the conditions for forming the second metal oxide layer were changed to the same conditions as in Comparative Example 4. , a transparent conductive film 10 was obtained.

(Comparative Example 6)
<Production of transparent conductive film 11>
In Example 3, the same procedure as in Example 3 was performed except that the conditions for forming the first metal oxide layer and the conditions for forming the second metal oxide layer were changed to the same conditions as in Comparative Example 4. , a transparent conductive film 11 was obtained.

(Comparative Example 7)
<Production of transparent conductive film 12>
In Example 1, the conditions for forming the first metal oxide layer were adjusted to a film forming pressure of 0.37 Pa and an input power density of 3.3 W/cm ² under the introduction of argon gas and oxygen gas (argon: oxygen = 98:2), sputtering ITO containing 90% by mass of indium oxide and 10% by mass of tin oxide, changing the average thickness to 43 nm, and further increasing the average thickness of the second metal oxide layer to 43 nm. A transparent conductive film 12 was obtained in the same manner as in Example 1, except for changing as follows.

(Comparative Example 8)
<Production of transparent conductive film 13>
In Example 2, a transparent A conductive film 13 was obtained.

(Comparative Example 9)
<Production of Transparent Conductive Film 14>
In Example 3, a transparent A conductive film 14 was obtained.

(Comparative Example 10)
<Production of Transparent Conductive Film 15>
In Example 1, the conditions for forming the first metal oxide layer were the same as the conditions for forming the second metal oxide layer, and the average thickness of the first metal oxide layer and the second metal oxide layer was A transparent conductive film 15 was obtained in the same manner as in Example 1, except that the thickness was changed to 43 nm.

(Comparative Example 11)
<Production of Transparent Conductive Film 16>
In Example 2, the same conditions as in Example 2 were repeated except that the conditions for forming the first metal oxide layer and the average thickness of the second metal oxide layer and the average thickness of the second metal oxide layer were changed to the same conditions as in Comparative Example 10. Thus, a transparent conductive film 16 was obtained.

(Comparative Example 12)
<Production of Transparent Conductive Film 17>
In Example 3, the same conditions as in Example 3 were repeated except that the conditions for forming the first metal oxide layer and the average thickness of the second metal oxide layer and the average thickness of the second metal oxide layer were changed to the same conditions as in Comparative Example 10. Thus, a transparent conductive film 17 was obtained.

(Comparative Example 13)
<Production of Transparent Conductive Film 18>
In Example 2, the average thickness of the first metal oxide layer was changed to 55 nm, and the pressure during film formation was adjusted to 0.37 Pa and the input power density to 3.3 W / cm ² on the metal layer, Under the introduction of argon gas and oxygen gas (argon:oxygen=95:5), ZTO containing 70% by mass of zinc oxide and 30% by mass of tin oxide was sputtered to form a second metal oxide layer with an average thickness of 40 nm. A transparent conductive film 18 was obtained in the same manner as in Example 2, except that

In addition, the average thickness of each layer in the produced transparent conductive film was measured as follows.
First, a substrate on which a first metal oxide layer, a metal layer, or a second metal oxide layer having a plurality of levels of predetermined thickness is formed is prepared, and a physical film thickness of each layer having a plurality of levels of predetermined thickness is obtained. was measured with a contact-type profilometer.
Also, the first metal oxide layer, the metal layer, or the second metal oxide layer in the predetermined thickness of the first metal oxide layer, the metal layer, or the second metal oxide layer at the plurality of levels was measured by quantitative analysis using a fluorescent X-ray measuring device (XRF, manufactured by Rigaku Corporation).
A calibration curve was prepared from the film thickness measured by the contact profilometer and the material amount of each layer measured by quantitative analysis using an X-ray fluorescence spectrometer (XRF). The transparent conductive film was subjected to quantitative analysis using an X-ray fluorescence spectrometer (XRF) to detect elements derived from each layer, and the average value of the measured values at 10 locations was taken as the average thickness.
For the average thickness of the first metal oxide layer, the fluorescence X-ray intensity of zinc derived from the first metal oxide layer is detected, and for the average thickness of the metal layer, the fluorescence X-ray intensity of silver derived from the metal layer is detected. The line intensity was detected, and the fluorescent X-ray intensity of indium derived from the second metal oxide layer was detected for the average thickness of the second metal oxide layer.
In addition, the average thickness of the underlayer is measured using a UV-visible spectrophotometer (UV3600, manufactured by Shimadzu Corporation) for the reflected waveform of the substrate on which the underlayer is formed, and the average thickness (height) of the underlayer is determined. Calculated.
For each layer, the average value of the measured values at 10 locations was taken as the average thickness. The results are shown in Tables 1-4.

In addition, for the obtained transparent conductive films 1 to 18, the arithmetic surface roughness Ra of the surface of the second metal oxide was measured with a light interference type surface roughness meter (WYKO Contour GT K1M manufactured by Bruker Japan Co., Ltd.) Condition: Measured using VSI mode). The results are shown in Tables 1-4.

Next, the obtained transparent conductive films 1 to 17 were heat-treated for 30 minutes in a constant temperature device (device name: DRX420DA, manufactured by ADVANTEC Co., Ltd.) at 150°C.
After the heat treatment, crystallinity of the second metal oxide layer in the transparent conductive film was confirmed by the following X-ray crystal diffraction method. Regarding the transparent conductive film 18, since ZTO was used for the second metal oxide layer, the crystallinity of the second metal oxide layer was not confirmed.
Specifically, it was confirmed by the following method.
First, X-ray crystal diffraction was performed under the following conditions.
<Measurement conditions for X-ray crystal diffraction>
・ Device name: X-ray crystal diffraction device (XRD6100, manufactured by Shimadzu Corporation)
・Standard mode ・X-ray source: CuKα
・Tube voltage: 40 kV
・Tube current: 30mA
・Drive shaft: 2θ/θ
・Scanning speed: 2.00°/min
・Scanning step: 0.02°
・Scanning range: Measure diffraction intensity from 29° to 32° ・Goniometer: vertical type ・Divergence slit: 1°
・Scattering slit: 1°
・Receiving slit: 0.30mm
The raw data of the spectra obtained by X-ray crystallography for transparent conductive films 1-17 are shown in FIGS. 2A-2Q, respectively. The presence or absence of detection of a peak at 2θ=29° to 32° corresponding to the (222) plane measured by X-ray crystal diffraction was judged based on the following method. The results are shown in Tables 1-4.
The following values <1> to <3> are calculated based on the measured raw data.
<1> Maximum value of diffraction intensity in the range of 30° to 31° <2> Value obtained by adding diffraction intensity at 29° and 32° and dividing by 2 <3> Value obtained by dividing <1> by <2><1> Maximum value of diffraction intensity in the range of 30° to 31°” is higher when the ITO in the second metal oxide layer is crystallized than when the ITO is not crystallized. .
Further, "<1> the maximum value of the diffraction intensity in the range of 30° to 31°" is "<2> the diffraction intensity at 29° and 32° when the ITO in the second metal oxide layer is not crystallized. is added and divided by 2".
In this embodiment, when "value obtained by dividing <3><1> by <2>" is 1.2 or more, it is determined that "a peak is detected", and "<3><1> is When the "value divided by <2>" was less than 1.2, it was determined that "no peak was detected".
In addition, in Tables 1 to 4, "ITO (amorphous)" means that ITO does not crystallize even after heat treatment at 150 ° C. for 30 minutes, and no X-ray diffraction peak is detected. “ITO (microcrystalline)” means that ITO was crystallized by heat treatment at 150° C. for 30 minutes and an X-ray diffraction peak was detected.

Next, the obtained transparent conductive film was subjected to a moisture and heat resistance test as follows.
[Moisture and heat resistance test]
Two sheets of each of the obtained transparent conductive films 1 to 18 were prepared, and one sheet of each transparent conductive film was left for 250 hours in a constant temperature and humidity apparatus at 60 ° C. and 95% RH. A humidity and heat resistance test was performed by leaving one sheet in a constant temperature and humidity apparatus at 85° C. and 85% RH for 250 hours.

Regarding the transparent conductive films 1 to 18 after the heat and humidity resistance test, "appearance evaluation", "conductivity (surface resistance measurement)", "transparency (total light transmittance)", and "adhesion properties (cross-cut peeling test)” was evaluated. The results are shown in Tables 1-4.

<Appearance evaluation>
After the moist heat resistance test, the appearance of the transparent conductive film was visually confirmed, and the state of silver aggregation (silver aggregate) in the metal layer was evaluated based on the following evaluation criteria. The results are shown in Tables 1-4. 3A (60° C., 95% RH, 250 hours) and FIG. 3B (85° C., 85% RH, 250 hours). An example of the photograph in the viewing state is shown in FIG. 3C (60° C., 95% RH, 250 hours) and FIG. 3D (85° C., 85% RH, 250 hours). White dotted spots in the photograph indicate silver agglomerates. If the evaluation result is 3 or more under the conditions of the humidity and heat resistance test "60°C, 95% RH, 250 hours" and the evaluation result is 2 or more under "85°C, 85% RH, 250 hours", there is no problem in practical use. is.
[Evaluation criteria]
3: 3 or less silver aggregates with a diameter of 0.5 mm or more exist in an area of 40 mm × 40 mm 2: 4 or more and less than 10 silver aggregates with a diameter of 0.5 mm or more exist in an area of 40 mm × 40 mm 1: There are 10 or more silver agglomerates with a diameter of 0.5 mm or more in an area of 40 mm x 40 mm

<Conductivity (measurement of surface resistance)>
The surface resistance value was measured for the transparent conductive film "before the heat and humidity resistance test" and "after the heat and humidity resistance test". The surface resistance value was measured at arbitrary 10 points with a low resistivity meter (manufactured by Mitsubishi Chemical Analytic Tech, model number: MCP-T610), and the average value was taken as the surface resistance value. The measurement results were evaluated according to the following evaluation criteria. Among the evaluation results of each condition of the moist heat resistance test ("60 ° C., 95% RH, 250 hours" and "85 ° C., 85% RH, 250 hours"), the worse evaluation result is the evaluation of the transparent conductive film. bottom. In addition, if the evaluation result in each condition of the moisture and heat resistance test is "O", it is a level that does not pose any problems in practical use.
[Evaluation criteria]
○: Surface resistance value is 30 Ω / □ or less ×: Surface resistance value is over 30 Ω / □

<Transparency (total light transmittance measurement)>
The total light transmittance was measured for the transparent conductive film before the heat and humidity resistance test and after the heat and humidity resistance test. The total light transmittance was measured according to JIS K7361-1/HAZE: JIS K7136 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., model number: NDH5000SP).

<Adhesion (crosscut peeling test)>
The adhesiveness of the transparent conductive film "before the moisture-heat resistance test" and "after the moisture-heat resistance test" was evaluated by a checkerboard peeling test.
Specifically, 11 incisions were made at equal intervals (1.5 mm) from the second metal oxide layer side, the direction was changed by 90°, and 11 incisions were made at equal intervals (1.5 mm). 100 squares cut in a grid of 10×10 pieces were prepared.
A cellophane tape (manufactured by Nichiban Co., Ltd., product number: CT405AP-18) was pasted thereon and adhered to the second metal oxide layer. After that, holding the end of the tape, the tape was instantaneously peeled off in a direction orthogonal to the bonded surfaces, and the peeling state of the second metal oxide was confirmed.
The results are shown in Tables 1-4. In the results, the numerator represents the number of masses remaining without peeling, and 100/100 represents the state without peeling. The measurement results were evaluated according to the following evaluation criteria. Among the evaluation results of each condition of the moist heat resistance test ("60 ° C., 95% RH, 250 hours" and "85 ° C., 85% RH, 250 hours"), the worse evaluation result is the evaluation of the transparent conductive film. bottom. In addition, if the evaluation result is 2 or more, it is a level that poses no problem in actual use.
[Evaluation criteria]
3: The number of remaining squares is 100/100
2: The number of remaining squares is 90/100 or more and less than 100/100 1: The number of remaining squares is less than 90/100

The results in Tables 1 to 4 show that the transparent conductive films of Examples 1 to 5 can maintain excellent appearance, conductivity, total light transmittance, and adhesion even after the wet heat resistance test.
From the results of FIGS. 2A to 2C and FIGS. 2P to 2Q, the content of tin oxide in the second metal oxide layer is 10% by mass with respect to the total amount of indium oxide and tin oxide. 2θ=29 corresponding to the X-ray diffraction measurement (222) plane than in Examples 4 and 5 in which the tin oxide content is 5% by mass with respect to the total amount of indium oxide and tin oxide. ° to 32° peak was less detected, indicating less crystallization.

This international application claims priority based on Japanese Patent Application No. 2021-203235 filed on December 15, 2021 and Japanese Patent Application No. 2022-173639 filed on October 28, 2022. Yes, the entire contents of Japanese Patent Application No. 2021-203235 and Japanese Patent Application No. 2022-173639 are incorporated into this international application.

REFERENCE SIGNS LIST 10 transparent conductive film 11 substrate 12a first metal oxide layer 12b second metal oxide layer 13 metal layer 14 base layer

Claims

A transparent conductive film having a substrate, a first metal oxide layer, a metal layer, and a second metal oxide layer in this order,
The first metal oxide layer contains zinc oxide and tin oxide,
the metal layer contains at least one of silver and a silver alloy,
The second metal oxide layer contains indium oxide and tin oxide,
A transparent conductive film characterized in that no peak is detected at 2θ = 29° to 32° when measured by X-ray crystal diffraction after heat treatment at 150°C for 30 minutes.
The transparent conductive film according to claim 1, wherein the second metal oxide layer has an arithmetic mean roughness Ra of 15 nm or less.
The transparent conductive material according to any one of claims 1 and 2, wherein the content of tin oxide in the second metal oxide layer is 5% by mass or more with respect to the total amount of the indium oxide and the tin oxide. the film.
3. The transparent conductive film according to claim 1, which has a total light transmittance of 82% or more as measured according to JIS K7361-1.