JP7620041B2 - Light-transmitting conductive layer and light-transmitting conductive sheet - Google Patents

Description

The present invention relates to a light-transmitting conductive layer and a light-transmitting conductive sheet.

Conventionally, a light-transmitting conductive sheet is known that includes a substrate and a light-transmitting conductive layer in that order. Such light-transmitting conductive sheets are suitable for use in various devices (e.g., touch sensors).

As such a light-transmitting conductive sheet, for example, a light-transmitting conductive sheet has been proposed that includes a resin layer and a light-transmitting conductive layer, in that order, toward one side in the thickness direction, and the light-transmitting conductive layer includes a first region that is amorphous and a second region that is crystalline, in that order, toward one side in the thickness direction (see, for example, Patent Document 1).

International Publication No. 2021/241118 Brochure

On the other hand, the light-transmitting conductive layer is required to have a lower resistivity. In order to lower the resistivity, it has been considered to increase the thickness of the light-transmitting conductive layer, but this has the disadvantage of reducing the flexibility of the light-transmitting conductive layer.

The present invention aims to provide a light-transmitting conductive layer that has low resistivity and excellent flexibility, and a light-transmitting conductive sheet that includes the light-transmitting conductive layer.

The present invention [1] is a light-transmitting conductive layer having a first main surface and a second main surface that face each other in the thickness direction, and a first region including the first main surface and a second region including the second main surface are sequentially arranged toward one side in the thickness direction, a main region of the first region is amorphous, a main region of the second region is crystalline, and the first region has a non-uniform thickness.

The present invention [2] includes the optically transparent conductive layer described in [1] above, in which the thickness of the second region is greater than the thickness of the first region.

The present invention [3] includes a light-transmitting conductive sheet comprising the light-transmitting conductive layer described in [1] or [2] above and a base layer located on the first main surface side of the light-transmitting conductive layer.

The light-transmitting conductive layer of the present invention has a second region that is crystalline. Therefore, it has low resistivity. Furthermore, in the light-transmitting conductive layer, the first region that is amorphous has a non-uniform thickness. Therefore, it has excellent flexibility.

The light-transmitting conductive sheet of the present invention comprises the light-transmitting conductive layer of the present invention. Therefore, it has low resistivity and excellent flexibility.

FIG. 1 shows one embodiment of the light-transmitting conductive layer and light-transmitting conductive sheet of the present invention. 2A to 2C show one embodiment of a method for producing a light-transmitting conductive layer and a light-transmitting conductive sheet. Fig. 2A shows a first step of preparing a base layer. Fig. 2B shows a third step of arranging a first region on one thickness-wise surface of the base layer in the second step. Fig. 2C shows a fourth step of arranging a second region on one thickness-wise surface of the first region in the second step.

With reference to Figure 1, one embodiment of the light-transmitting conductive layer and light-transmitting conductive sheet of the present invention will be described.

In Figure 1, the up-down direction on the paper surface is the up-down direction (thickness direction). The upper side of the paper surface is the top side (one side in the thickness direction). The lower side of the paper surface is the bottom side (the other side in the thickness direction). The left-right direction and depth direction on the paper surface are surface directions that are perpendicular to the up-down direction. Specifically, they follow the directional arrows in each figure.

The light-transmitting conductive sheet 1 has a film shape (including a sheet shape) with a predetermined thickness. The light-transmitting conductive sheet 1 extends in a plane direction perpendicular to the thickness direction. The light-transmitting conductive sheet 1 has a flat upper surface and a flat lower surface. The light-transmitting conductive sheet 1 is preferably flexible.

As shown in FIG. 1, the light-transmitting conductive sheet 1 comprises a base layer 2 and a light-transmitting conductive layer 3 arranged on one side of the base layer 2 in the thickness direction. In other words, the light-transmitting conductive sheet 1 comprises a light-transmitting conductive layer 3 and a base layer 2 located on the first main surface 11 (described later) side of the light-transmitting conductive layer 3. More specifically, the light-transmitting conductive sheet 1 comprises a base layer 2 and a light-transmitting conductive layer 3 arranged directly on the upper surface (one side in the thickness direction) of the base layer 2. The light-transmitting conductive sheet 1 preferably comprises a base layer 2 and a light-transmitting conductive layer 3.

The thickness of the light-transmitting conductive sheet 1 is, for example, 400 μm or less, preferably 200 μm or less, and, for example, 1 μm or more, preferably 5 μm or more.

<Base layer>
The base material layer 2 has a film shape. The base material layer 2 is preferably flexible. The base material layer 2 is disposed on the entire lower surface of the light-transmitting conductive layer 3 so as to be in contact with the lower surface of the light-transmitting conductive layer 3. The base material layer 2 is the bottom layer of the light-transmitting conductive sheet 1.

The substrate layer 2 includes a substrate 10. The substrate layer 2 is made of a substrate 10.

[Substrate]
Examples of the substrate 10 include a polymer film and glass. From the viewpoint of flexibility, the substrate 2 is preferably a polymer film.

Examples of materials for the polymer film include polyester resin, (meth)acrylic resin, olefin resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of (meth)acrylic resin include polymethyl methacrylate. Examples of olefin resin include polyethylene, polypropylene, and cycloolefin polymer. Examples of cellulose resin include triacetyl cellulose.

The polymer film is preferably made of polyester resin. The polymer film is more preferably made of polyethylene terephthalate.

The thickness of the substrate 10 is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and, for example, 200 μm or less, preferably 150 μm or less, more preferably 130 μm or less.

The thickness of the substrate 10 can be measured using a dial gauge (PEACOCK, "DG-205").

The substrate 10 is preferably transparent. Specifically, the total light transmittance (JIS K 7375-2008) of the substrate layer 2 is, for example, 50% or more, preferably 70% or more, more preferably 80% or more, and preferably 85% or more.

<Light-transmitting conductive layer>
The light-transmitting conductive layer 3 has a film shape. The light-transmitting conductive layer 3 is disposed on the entire upper surface of the base material layer 2 so as to be in contact with the upper surface of the base material layer 2. The light-transmitting conductive layer 3 is the uppermost layer of the light-transmitting conductive sheet 1.

The light-transmitting conductive layer 3 has a first main surface 11 and a second main surface 12 that face each other in the thickness direction.

The first main surface 11 is a flat surface. The first main surface 11 contacts one side of the base layer 2 in the thickness direction.

The second main surface 12 is exposed to one side in the thickness direction. The second main surface 12 is a flat surface that is approximately parallel to the first main surface 11.

Examples of the material of the light-transmitting conductive layer 3 include conductive oxides. Examples of the conductive oxides include metal oxides containing at least one metal or semi-metal selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. If necessary, the metal oxide may be doped with a metal atom or semi-metal atom shown in the above group.

Examples of conductive oxides include metal oxides. Examples of metal oxides include indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium gallium oxide (IGO), indium tin oxide (ITO), and antimony tin oxide (ATO).

From the viewpoint of improving transparency and electrical conductivity, the conductive oxide is preferably indium tin oxide (ITO). In the following description, a detailed description will be given of the case where the material of the light-transmitting conductive layer 3 is indium tin oxide (ITO).

In indium tin oxide (ITO), the concentration of tin oxide is, for example, 0.1% by mass or more, preferably 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, for example, 30% by mass or less, preferably 15% by mass or less.

The light-transmitting conductive layer 3 has a first region 21 and a second region 22 arranged in sequence toward one side in the thickness direction.

[First Region]
The first region 21 includes the first main surface 11. The first region 21 is the other thickness-wise side portion of the light-transmitting conductive layer 3. The first region 21 includes the other thickness-wise surface of the light-transmitting conductive layer 3. The first region 21 is formed across the entire surface of the light-transmitting conductive layer 3. The first main surface 11 is the other thickness-wise surface of the first region 21.

The main region of the first region 21 is amorphous. More specifically, the first region 21 includes a region that is amorphous as the main region in a cross-sectional view. Specifically, examples of such a configuration of the first region 21 include a configuration in which all regions in the first region 21 are amorphous in a cross-sectional view, and a configuration in which the main region of the first region 21 is amorphous and the remaining small region is crystalline in a cross-sectional view.

The amorphous nature of the first region 21 is confirmed by observing a cross-sectional TEM image. In addition, by observing the presence or absence of lattice fringes and the percentage of the region in which lattice fringes are observed using high-magnification cross-sectional TEM observation, it is possible to identify that the first region 21 is amorphous and/or that the region is predominantly amorphous.

In addition, in a cross-sectional view, the area ratio of the main region in the first region 21 (amorphous area ratio) is, for example, 0.6 or more, preferably 0.8 or more, more preferably 0.9 or more, and is, for example, 1 or less.

The first region 21 also has a non-uniform thickness. Specifically, the first surface 13 on the opposite side of the first main surface 11 in the first region 21 has a non-uniform surface.

More specifically, the first region 21 has a non-uniform thickness means that in a cross-sectional image of the light-transmitting conductive layer 3, the difference between the thickness at the position where the first region 21 is thickest and the thickness at the position where the first region 21 is thinnest is 5 nm or more. The thickness of the first region 21 is determined from the difference between the first surface 13 and the first main surface 11. More details will be provided in the examples described below.

Furthermore, such a first region 21 can be formed, for example, by setting the water pressure in the sputtering process described below within a predetermined range.

The minimum thickness of the first region 21 is preferably thinner than the thickness (minimum thickness) of the second region 22 described below, and is, for example, 1 nm or more, preferably 3 nm or more, more preferably 5 nm or more, and for example, 50 nm or less, preferably 30 nm or less, more preferably 20 nm or less.

The ratio of the thickness (minimum thickness) of the first region 21 to the thickness (minimum thickness) of the light-transmitting conductive layer 3 is, for example, 0.02 or more, preferably 0.04 or more, and, for example, 0.10 or less, preferably 0.08 or less, more preferably 0.05 or less.

If the above ratio is within the above range, it is possible to improve flexibility while maintaining low resistivity.

The method for measuring the thickness (minimum thickness) of the first region 21 will be described in detail in the examples below.

[Second Region]
The second region 22 includes the second main surface 12. The second region 22 is a portion on one side in the thickness direction of the light-transmitting conductive layer 3. The second region 22 includes one surface in the thickness direction of the light-transmitting conductive layer 3. The second region 22 is continuous with one side in the thickness direction of the first region 21. The second region 22 is formed across the entire surface direction of the light-transmitting conductive layer 3. The second main surface 12 is one surface in the thickness direction of the second region 22.

The main region of the second region 22 is crystalline. More specifically, the second region 22 includes a region that is crystalline as the main region in a cross-sectional view. Specifically, examples of such a configuration of the second region 22 include a configuration in which all regions in the second region 22 are crystalline in a cross-sectional view, and a configuration in which the main region of the second region 22 is crystalline and the remaining small region is amorphous in a cross-sectional view.

The crystallinity of the second region 22 is confirmed by observing a cross-sectional TEM image. In addition, by observing the presence or absence of lattice fringes and the proportion of the region in which lattice fringes are confirmed by high-magnification cross-sectional TEM observation, it is possible to identify that the second region 22 is crystalline and/or that the region is mainly crystalline. In addition, when the second region 22 is crystalline, for example, the second region 22 is immersed in a 5% by mass hydrochloric acid aqueous solution for 15 minutes, washed with water and dried, and the two-terminal resistance is measured over a distance of about 15 mm on the surface of the second region 22, and the two-terminal resistance is 10 kΩ or less.

In addition, in a cross-sectional view, the area ratio of the main region in the second region 22 (the area ratio of the crystalline material) is, for example, 0.7 or more, preferably 0.8 or more, more preferably 0.9 or more, and is, for example, 1 or less.

The second region 22 has a non-uniform thickness. Specifically, the second surface 14 on the opposite side of the second main surface 12 in the second region 22 has a non-uniform surface that corresponds to the first surface 13.

The second region 22 is disposed on one side of the first region 21 in the thickness direction, so if the first region 21 has a non-uniform thickness, the second region 22 also has a non-uniform thickness.

From the viewpoint of low resistivity and flexibility, the thickness (minimum thickness) of the second region 22 is preferably thicker than the thickness (minimum thickness) of the first region 21, for example, more than 70 nm, preferably 80 nm or more, more preferably 90 nm or more, and for example, 150 nm or less, preferably 120 nm or less, more preferably 110 nm or less.

The ratio of the thickness (minimum thickness) of the second region 22 to the thickness (minimum thickness) of the light-transmitting conductive layer 3 is, for example, 0.90 or more, preferably 0.92 or more, more preferably 0.95 or more, and is, for example, 0.98 or less, preferably 0.96 or less.

If the above ratio is within the above range, it is possible to improve flexibility while maintaining low resistivity.

The method for measuring the thickness (minimum thickness) of the second region 22 will be described in detail in the examples below.

If the thickness (minimum thickness) of the second region 22 is greater than the thickness (minimum thickness) of the first region, the flexibility can be further improved.

The ratio of the thickness (minimum thickness) of the second region 22 to the thickness (minimum thickness) of the first region 21 is, for example, more than 1, preferably 2.0 or more, more preferably 4.0 or more, even more preferably 7 or more, particularly preferably 15 or more, and is, for example, 50 or less, preferably 25 or less.

If the above ratio is within the above range, it is possible to improve flexibility while maintaining low resistivity.

[Physical Properties of Light-Transmitting Conductive Layer]
The thickness (minimum thickness) of the light-transmitting conductive layer 3 is the sum of the thickness of the first region 21 and the thickness of the second region 22, and from the viewpoint of low resistance, is, for example, 80 nm or more, preferably 100 nm or more, and for example, 200 nm or less, preferably 150 nm or less, and more preferably 120 nm or less.

The total light transmittance (JIS K 7375-2008) of the light-transmitting conductive layer 3 is, for example, 60% or more, preferably 80% or more, more preferably 85% or more, and for example, 100% or less.

The surface resistance of the light-transmitting conductive layer 3 is, for example, 40 Ω/□ or less, preferably 35 Ω/□ or less, and for example, more than 0 Ω/□. The surface resistance can be measured by a four-terminal method in accordance with JIS K7194.

The resistivity of the light-transmitting conductive layer 3 is, for example, 2.8×10 ⁻⁴ Ωcm or less, more preferably 2.5×10 ⁻⁴ Ωcm or less, and for example, more than 0 Ωcm, preferably 0.1×10 ⁻⁴ Ωcm or more, more preferably 1.0×10 ⁻⁴ Ωcm or more. The resistivity is obtained by multiplying the surface resistance by the thickness.

<Method for producing light-transmitting conductive sheet>
A method for producing the light-transmitting conductive sheet 1 will be described with reference to FIGS. 2A to 2C.

The method for manufacturing the light-transmitting conductive sheet 1 includes a first step of preparing the base layer 2, and a second step of disposing the light-transmitting conductive layer 3 on one surface of the base layer 2 in the thickness direction by a sputtering method. In this method, each layer is disposed in order, for example, by a roll-to-roll method. In such a case, the conveying speed is, for example, 1.0 m/min or more, and, for example, 20.0 m/min or less.

[First step]
In the first step, the base layer 2 is prepared.

To prepare the substrate layer 2, a substrate 10 is prepared as shown in FIG. 2A.

[Second step]
In the second step, the light-transmitting conductive layer 3 is disposed on one surface in the thickness direction of the base layer 2 by sputtering.

In detail, the second step includes a third step of arranging a first region 21 on one thickness-wise surface of the base layer 2, a fourth step of arranging a second region 22 on one thickness-wise surface of the first region 21, and a fifth step of crystallizing the second region 22 by heating.

(Third process)
In the third step, as shown in FIG. 2B, a first region 21 is disposed on one surface in the thickness direction of the base layer 2 by a sputtering method.

To place the first region 21 on one surface of the base layer 2 in the thickness direction by the sputtering method, a surface treatment is applied to one surface of the base layer 2 in the thickness direction, if necessary.

Surface treatments include, for example, corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, and saponification treatment.

Next, in the sputtering method, the target (the material of the first region 21) and the base material layer 2 are placed facing each other in a vacuum chamber. In addition, in the sputtering process, the base material layer 2 is in close contact with the film-forming roll along the circumferential direction.

Next, sputtering gas is supplied and a voltage is applied from a power source to accelerate the gas ions and irradiate the target, ejecting the target material from the target surface. The target material is then deposited on the surface (one side in the thickness direction) of the base layer 2 to form the first region 21.

Examples of the sputtering gas include an inert gas (e.g., krypton gas, argon gas) and oxygen gas. As the sputtering gas, preferably, an inert gas and oxygen gas are used in combination. As the inert gas, preferably, argon gas is used. When argon gas is used as the inert gas, the first region 21 contains argon atoms.

The amount of oxygen gas introduced is, for example, 1.0 flow% or more, preferably 2.0 flow% or more, and, for example, 5.0 flow% or less, preferably 3.0 flow% or less, relative to the total amount of inert gas and oxygen gas.

The air pressure during sputtering is, for example, 0.1 Pa or more, preferably 0.2 Pa or more, and, for example, 2.0 Pa or less, preferably 1.0 Pa or less.

The water pressure during sputtering is, for example, more than 0.5×10 ⁻⁴ Pa, preferably 0.6×10 ⁻⁴ Pa or more, more preferably 0.6×10 ⁻⁴ Pa or more, and for example, 1.8×10 ⁻⁴ Pa or less, preferably 1.5×10 ⁻⁴ Pa or less, more preferably 1.0×10 ⁻⁴ Pa or less.

If the water pressure during sputtering is within the above range, the first region 21 having a non-uniform thickness can be reliably formed.

In addition, if the water pressure during sputtering is within the above range, the first region 21 can be maintained amorphous in the fifth step.

The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source. It may also be a combination of these.

The discharge output is, for example, 1.0 kW or more, preferably 10.0 kW or more, and, for example, 20 kW or less.

The horizontal magnetic field strength of the target is, for example, 10 mT or more, preferably 20 mT or more, and, for example, 100 mT or less, preferably 50 mT or less.

The temperature of the film-forming roll is, for example, 20°C or lower, preferably 10°C or lower, more preferably 0°C or lower, and, for example, -50°C or higher, preferably -25°C or higher.

(Fourth step)
In the fourth step, as shown in FIG. 2C, the second region 22 is disposed on one surface in the thickness direction of the first region 21 by sputtering.

In the sputtering method, the target (material of the second region 22) and the first region 21 are placed facing each other in a vacuum chamber. Sputtering gas is then supplied and a voltage is applied from a power source to accelerate gas ions and irradiate the target, ejecting the target material from the target surface. The target material is then deposited on the surface of the first region 21 (one side in the thickness direction) to form the second region 22. In the sputtering process, the base layer 2 is in close contact with the film-forming roll in the circumferential direction.

The sputtering gas may be, for example, an inert gas (e.g., krypton gas, argon gas) or oxygen gas. The inert gas may preferably be argon gas. When argon gas is used as the inert gas, the second region 22 contains argon atoms.

The amount of oxygen gas introduced is, for example, 0.05 flow% or more, preferably 0.1 flow% or more, and, for example, 5.0 flow% or less, preferably 3.0 flow% or less, relative to the total amount of inert gas and oxygen gas.

The air pressure during sputtering is, for example, 0.1 Pa or more, preferably 0.2 Pa or more, and, for example, 2.0 Pa or less, preferably 1.0 Pa or less.

The water pressure during sputtering is preferably higher than the water pressure in the third step, and is, for example, more than 1.8×10 ⁻⁴ Pa, preferably 2.0×10 ⁻⁴ Pa or more, and for example, 4.0×10 ⁻⁴ Pa or less, preferably 3.0×10 ⁻⁴ Pa or less, more preferably 2.5×10 ⁻⁴ Pa or less.

If the water pressure during sputtering is within the above range, the second region 22 can be reliably crystallized in the fifth step.

The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source. It may also be a combination of these.

The discharge output is, for example, 1.0 kW or more, preferably 10.0 kW or more, and, for example, 20 kW or less.

The horizontal magnetic field strength of the target is, for example, 10 mT or more, and, for example, 200 mT or less, preferably 100 mT or less, and more preferably 40 mT or less.

The temperature of the film-forming roll is, for example, 20°C or lower, preferably 10°C or lower, more preferably 0°C or lower, and, for example, -50°C or higher, preferably -25°C or higher.

(Fifth step)
In the fifth step, the second region 22 is crystallized by heating.

To crystallize the second region 22, the second region 22 is heated. Specifically, after sputtering, the second region 22 is heated using a heating roll.

Heating conditions include a heating temperature of, for example, 100°C or higher, preferably 120°C or higher, and for example, 250°C or lower, preferably 200°C or lower, and a heating time of, for example, 10 minutes or longer, and for example, 120 minutes or shorter.

As a result, the second region 22 crystallizes. Meanwhile, the first region 21 does not crystallize and remains amorphous. In detail, if the water pressure in the third step is within the above range, the combined amount of impurity gas derived from the rare gas and water is at a suitable level for maintaining the amorphous state, and the first region 21 does not crystallize and remains amorphous. Also, if the water pressure in the fourth step is within the above range, the amount of impurities is insufficient to obtain crystallinity, and the second region 22 crystallizes.

By the above steps, the light-transmitting conductive sheet 1 is obtained.

<Action and effect>
The light-transmitting conductive layer 3 includes the second region 22 which is crystalline. Therefore, the light-transmitting conductive layer 3 has a low resistivity. Furthermore, in the light-transmitting conductive layer 3, the first region 21 which is amorphous has a non-uniform thickness. Therefore, the light-transmitting conductive layer 3 has excellent flexibility.

In more detail, when the amorphous first region 21 in the light-transmitting conductive layer 3 has a non-uniform thickness, the first region 21 relieves stress caused by bending. As a result, the bendability can be improved.

The light-transmitting conductive sheet 1 includes a light-transmitting conductive layer 3. As a result, it has low resistivity and excellent flexibility.

<Modification>
In the modified example, the same reference numerals are used for the same components and steps as those in the first embodiment, and detailed descriptions thereof will be omitted. In addition, the modified example can achieve the same effects as those in the first embodiment, unless otherwise specified. Furthermore, the first embodiment and its modified example can be appropriately combined.

In the above description, the base layer 2 is made of the base material 10, but the base layer 2 can also further include a cured resin layer. In such a case, the base layer 2 includes the base material 10 and the cured resin layer in order toward one side in the thickness direction.

Cured resin layers include dielectric layers and hard coat layers.

In the above description, the crystalline state of the first region 21 and the second region 22 is adjusted by adjusting the water pressure in the third and fourth steps to a predetermined range. However, for example, the crystalline state of the first region 21 and the second region 22 can also be adjusted by adjusting the power density in the third and fourth steps to a predetermined range.

In the above description, the first surface 13 opposite the first main surface 11 in the first region 21 has an uneven surface, but the first surface 13 may not have an uneven surface (i.e., have a flat surface) and the first main surface 11 may have an uneven surface. Even in such a case, the first region 21 has an uneven thickness. Also, in such a case, the second surface 14 in the second region 22 has a flat surface.

In addition, in the first region 21, the first main surface 11 and the first surface 13 may have a non-uniform surface. Even in such a case, the first region 21 has a non-uniform thickness. In addition, in such a case, the second surface 14 in the second region 22 has a non-uniform surface.

Preferably, from the viewpoint of improving flexibility, in the first region 21, the first surface 13 has an uneven surface, and the first main surface 11 has a flat surface. In such a case, in the second region 22, the second surface 14 in the second region 22 has an uneven surface.

The present invention will be described in more detail below with reference to examples and comparative examples. Note that the present invention is in no way limited to the examples and comparative examples. Furthermore, the specific numerical values of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values (numerical values defined as "equal to or less than") or lower limit values (numerical values defined as "equal to or more than" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention."

<Production of Light-Transmitting Conductive Layer and Light-Transmitting Conductive Sheet>
Example 1
[First step]
A long PET film (thickness: 125 μm, manufactured by Mitsubishi Chemical Corporation) was prepared as a substrate, thereby preparing a substrate layer.

[Second step]
A light-transmitting conductive layer was disposed on one surface of the base layer in the thickness direction by a reactive sputtering method. In the reactive sputtering method, a sputtering deposition apparatus (DC magnetron sputtering apparatus) capable of performing a film formation process by a roll-to-roll method was used.
(Third process)
Specifically, first, the first region was disposed on one surface in the thickness direction of the base layer.

Specifically, a sintered body of indium oxide and tin oxide (tin oxide concentration was 12.5% by mass) was used as the target. A DC power source was used as the power source for applying a voltage to the target. The horizontal magnetic field strength on the target was 30 mT. In the sputtering device, the base material layer was attached to the film-forming roll along the circumferential direction. The temperature of the film-forming roll was set to -5°C. After the sputtering device was evacuated until the ultimate vacuum in the film-forming chamber of the sputtering device reached 0.9 x 10 ^-4 Pa, argon as a sputtering gas and oxygen as a reactive gas were introduced into the sputtering device, and the air pressure in the sputtering device was set to 0.2 Pa. In addition, sputtering was performed in an environment where the water pressure during sputtering was 0.8 x 10 ^-4 Pa. The ratio of the amount of oxygen introduced to the total amount of argon and oxygen introduced into the sputtering device was about 2.4 flow%. As a result, a first region (thickness: 5 to 20 nm (minimum thickness: 5 nm)) was disposed on one surface in the thickness direction of the base layer.

(Fourth step)
The second region was disposed on one surface in the thickness direction of the first region.

Specifically, a sintered body of indium oxide and tin oxide (tin oxide concentration was 12.5% by mass) was used as the target. A DC power source was used as the power source for applying a voltage to the target. The horizontal magnetic field strength on the target was 30 mT. In the sputtering device, the base material layer was adhered to the film-forming roll along the circumferential direction. The temperature of the film-forming roll was set to -5°C. After the sputtering device was evacuated until the ultimate vacuum in the film-forming chamber of the sputtering device reached 0.9 x 10 ^-4 Pa, argon as a sputtering gas and oxygen as a reactive gas were introduced into the sputtering device, and the air pressure in the sputtering device was set to 0.2 Pa. In addition, sputtering was performed in an environment where the water pressure during sputtering was 2.1 x 10 ^-4 Pa. The ratio of the amount of oxygen introduced to the total amount of argon and oxygen introduced into the sputtering device was about 2.3 flow%. As a result, a second region (thickness: 100 to 120 nm (minimum thickness: 100 nm)) was disposed on one surface in the thickness direction of the first region.

(Fifth step)
The second region was crystallized by heating. Specifically, the second region was heated in a hot air oven. The heating temperature was 140° C., and the heating time was 30 minutes. This caused the second region to crystallize. Meanwhile, the first region was not crystallized and maintained an amorphous state. In this manner, a light-transmitting conductive layer and a light-transmitting conductive sheet 1 were manufactured.

Comparative Example 1
A light-transmitting conductive layer and a light-transmitting conductive sheet were produced according to the same procedure as in Example 1. However, the water pressure in the third step was changed to 0.5×10 ⁻⁴ Pa.

Comparative Example 2
A light-transmitting conductive layer and a light-transmitting conductive sheet were produced according to the same procedure as in Example 1, except that the third step was not carried out.

Comparative Example 3
A light-transmitting conductive layer and a light-transmitting conductive sheet were produced according to the same procedure as in Example 1, except that the fifth step was not carried out.

<Evaluation>
[Thickness of Light-Transmitting Conductive Layer]
The thickness of the light-transmitting conductive layer (each region) of each Example and Comparative Example was measured by FE-TEM observation. Specifically, first, a cross-sectional observation sample of the light-transmitting conductive layer of each Example and Comparative Example was prepared by FIB microsampling. In the FIB microsampling method, an FIB device (trade name "FB2200", manufactured by Hitachi) was used, and the acceleration voltage was set to 10 kV. Next, the thickness of the light-transmitting conductive layer in the cross-sectional observation sample was measured by FE-TEM observation. In the FE-TEM observation, an FE-TEM device (trade name "JEM-2800", manufactured by JEOL) was used, and the acceleration voltage was set to 200 kV.

The thickness of the second region was calculated by subtracting the thickness of the first region from the thickness of the entire light-transmitting conductive layer. The results are shown in Table 1.

[Checking whether the first region 2 has an uneven thickness]
In the same manner as in the evaluation of the thickness of the light-transmitting conductive layer, the cross-sectional image of the FE-TEM was confirmed. At an observation magnification of 500,000 times (photographed area: horizontal length 275 nm), it was confirmed that the difference in thickness between the position where the first region 2 is the thickest and the position where the first region 21 is the thinnest was 5 nm or more in Example 1, and it was determined that the first region 2 has a non-uniform thickness.

[Resistance value]
The resistance value (R0) of the light-transmitting conductive layer of each Example and Comparative Example was measured by a four-terminal method. The resistance value was evaluated based on the following criteria. The results are shown in Table 1.
{standard}
A: The resistance value was 40 Ω/□ or less.
×: The resistance value exceeded 40 Ω/□.

[Flexibility]
The light-transmitting conductive sheets of each Example and Comparative Example were evaluated for their flexibility. Specifically, the light-transmitting conductive sheets of each Example and Comparative Example were cut to a width of 10 mm and a length of 150 mm to prepare samples. Then, the samples were placed on the mandrel so that the light-transmitting conductive layer was on the outside and the other surface of the substrate in the thickness direction was in contact with the mandrel. Then, both ends of the light-transmitting conductive sheet in the longitudinal direction were clipped, and a weight of 1000 g was attached to the center of the clip. That is, a load of 100 g/mm was applied downward relative to the width of the light-transmitting conductive sheet to fold the light-transmitting conductive sheet. This folded state was maintained for 10 seconds.

In this bent state, a marker was applied to the bent portion, and then the bent portion was released and the marker was observed under a microscope. In this test method, the diameter of the mandrel was changed from large to small in 1 mm increments, and the smallest diameter at which no cracks were observed under the microscope in the marker-painted portion is listed in Table 1. The smaller this value, the better the bending resistance can be evaluated. The results are shown in Table 1.

In the above test, the mandrel diameter was changed from large to small in increments of 1 mm, and the sample was changed each time the diameter was changed. In other words, in the above test, each sample was bent once, and each time it was bent, it was changed to a different sample (a different sample manufactured under the same conditions).

Reference Signs List 1 Light-transmitting conductive sheet 2 Base layer 3 Light-transmitting conductive layer 11 First main surface 12 Second main surface 21 First region 22 Second region

Claims (2)

A light-transmitting conductive sheet comprising a light-transmitting conductive layer and a polymer film substrate layer,
The light-transmitting conductive layer is
The substrate has a first main surface and a second main surface opposed to each other in a thickness direction ,
A first region including the first main surface and a second region including the second main surface are provided in this order toward one side in a thickness direction,
a major portion of the first region is an amorphous conductive oxide;
a major portion of the second region is a crystalline conductive oxide;
the first region has a non-uniform thickness;
The polymer film substrate layer is located on the first main surface side of the light-transmitting conductive layer.
The optically transparent conductive sheet according to claim 1 , wherein the second region has a thickness greater than a thickness of the first region.

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