Transparent conductive film, laminate, and method for manufacturing transparent conductive film

Abstract

The transparent conductive film 3 has polycrystals 31. The polycrystals 31 have crystal grains 32. The average value Df of the maximum Feret diameter of the crystal grains 32 is 160 nm to 400 nm.

Description

Technical Field

[0001] The present invention relates to a transparent conductive film, a laminate, and a method for manufacturing a transparent conductive film. Background Art

[0002] Conventionally, a transparent conductive film in a polycrystalline state has been known.

[0003] For example, Patent Document 1 describes a substrate with a conductor, the substrate with a conductor having a transparent conductive film, and a metal coating formed on a required portion of the transparent conductive film. The transparent conductive film is a film having a crystal grain size in the <222> direction by X-ray diffraction method of or more. Thus, a strong adhesion strength can be obtained between the transparent conductive film and the metal coating. In addition, the transparent conductive film is in a polycrystalline state.

[0004] On the other hand, a technique for preventing deterioration of a transparent conductive layer by a gas barrier layer has been known. For example, Patent Document 2 describes a transparent conductive film having a resin substrate, a gas barrier layer, and a transparent conductive layer. In the transparent conductive film, the gas barrier layer is formed between the resin substrate and the transparent conductive layer. The permeation of water vapor is suppressed by the gas barrier layer, thereby preventing deterioration of the transparent conductive layer. In the transparent conductive film, for example, the water vapor transmission rate under high humidity conditions of 40 °C and 90% RH is 0.1 g / m 2 / day or less.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 5-151827

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2014-201800 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] According to the technique described in Patent Document 1, the crystal grain size in the <222> direction of the transparent conductive film by X-ray diffraction method is determined in view of improving the adhesion strength between the transparent conductive film and the metal coating, and in Patent Document 1, no study has been made on the durability of the transparent conductive film in a high temperature and high humidity environment.

[0011] According to the technique described in Patent Document 2, a gas barrier layer is required to prevent deterioration of the transparent conductive layer.

[0012] In view of the above circumstances, the present invention provides a transparent conductive film having high durability in a high temperature and high humidity environment even when no gas barrier layer is present in the vicinity of the transparent conductive film. In addition, the present invention provides a method advantageous for manufacturing such a transparent conductive film.

[0013] Method for solving problems

[0014] The present invention provides a transparent conductive film, wherein the transparent conductive film has polycrystals, and the polycrystals have grains with an average value of the maximum Feret diameter of 160 nm to 400 nm.

[0015] In addition, the present invention provides a laminate, wherein the laminate has:

[0016] a substrate, and

[0017] the transparent conductive film disposed on the substrate.

[0018] In addition, the present invention provides a method for manufacturing a transparent conductive film, wherein the method for manufacturing a transparent conductive film includes:

[0019] forming a film on a substrate by sputtering; and

[0020] annealing the film to form a transparent conductive film, and

[0021] in the sputtering, adjusting the pressure of the inert gas to 0.4 Pa or less.

[0022] Advantages of the invention

[0023] The above-mentioned transparent conductive film has high durability in a high-temperature and high-humidity environment even when there is no gas barrier layer near the transparent conductive film. The above method is beneficial to manufacturing the above-mentioned transparent conductive film. Description of the drawings

[0024] Figure 1 A cross-sectional view showing an example of the laminate of the present invention.

[0025] Figure 2 Schematically showing Figure 1 a diagram of the structure of the film surface of the transparent conductive film shown.

[0026] Figure 3 A cross-sectional view showing an example of a heater having the laminate of the present invention.

[0027] Figure 4 A cross-sectional view showing another example of a heater having the laminate of the present invention.

[0028] Figure 5 Showing Figure 3 a cross-sectional view of an example of an article with a heater having the heater shown.

[0029] Figure 6 A diagram schematically illustrating a method for measuring the internal stress of a transparent conductive film.

[0030] Figure 7A The transmission electron microscope (TEM) photograph of the film surface of the transparent conductive film of Example 1.

[0031] Figure 7B To show Figure 7A The figure showing the boundaries between the crystal grains in the photograph shown.

[0032] Figure 8A The TEM photograph of the film surface of the transparent conductive film of Comparative Example 1.

[0033] Figure 8B To show Figure 8A The figure showing the boundaries between the crystal grains in the photograph shown. Detailed Description of the Invention

[0034] If the durability of the transparent conductive film in a high-temperature and high-humidity environment can be improved even when there is no gas barrier layer near the transparent conductive film, the value of the transparent conductive film is further increased. For example, if such a transparent conductive film can be used in information terminals with touch panels such as smartphones and in heaters and other fields, high-value-added products can be provided. For example, in-vehicle devices are required to function properly even in harsh environments. Therefore, it is advantageous for using the transparent conductive film in in-vehicle devices that the transparent conductive film has durability even in harsh environments. On the other hand, it has been conventionally considered that, in order to improve the durability of the transparent conductive film, as in the technique described in Patent Document 2, it is necessary to provide a gas barrier layer near the transparent conductive film. Therefore, the inventors of the present invention have repeatedly and intensively studied a technique for improving the durability of the transparent conductive film in a high-temperature and high-humidity environment even when there is no gas barrier layer near the transparent conductive film. The inventors have repeatedly made a large number of trials and errors, and as a result, newly found that it is advantageous for improving the durability of the transparent conductive film in a high-temperature and high-humidity environment that the transparent conductive film has a specified polycrystal. Based on this new finding, the inventors have finally completed the present invention.

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description is for illustratively explaining the present invention, and the present invention is not limited to the following embodiments. It should be noted that, in this specification, "transparent" typically means transparent to visible light.

[0036] As Figure 1 shown, the laminate 1 has a substrate 2 and a transparent conductive film 3. The transparent conductive film 3 is disposed on the substrate 2. Thus, the transparent conductive film 3 is typically provided in a state of being disposed on the substrate 2.

[0037] As Figure 2As shown, the transparent conductive film 3 has polycrystals 31. The polycrystals 31 have crystal grains 32. The average value Df of the maximum Feret diameter of the crystal grains 32 is 160 nm to 400 nm. Since the average value Df is 160 nm or more, water vapor hardly permeates through the transparent conductive film 3, and even if there is no gas barrier layer near the transparent conductive film 3, the transparent conductive film 3 can exhibit high durability in a high-temperature and high-humidity environment. In addition, since the average value Df is 400 nm or less, even if the transparent conductive film 3 is subjected to bending stress, cracks hardly occur in the transparent conductive film 3. Therefore, the transparent conductive film 3 can exhibit high durability in a high-temperature and high-humidity environment. The average value Df can be determined, for example, by a method including the following steps (I), (II), and (III).

[0038] (I) Based on the contrast difference, etc., of the images of adjacent crystal grains 32 in fields of 400 nm square randomly selected at 10 or more locations on the film surface TEM photograph of the transparent conductive film 3, the boundaries between the crystal grains 32 are determined.

[0039] (II) Based on the boundaries determined in step (I), the maximum Feret diameter of each crystal grain 32 contained in each field of view is determined. This determination is performed for the crystal grains 32 that can be observed as a whole in each field of view.

[0040] (III) Based on the maximum Feret diameter of each crystal grain 32 determined in step (II), the average value Df of the maximum Feret diameter of the crystal grains 32 is determined by arithmetic mean.

[0041] A prescribed durability test is performed on the transparent conductive film 3. In this case, the sheet resistance Rp [Ω / □] of the transparent conductive film 3 after the durability test and the sheet resistance Rb [Ω / □] of the transparent conductive film 3 before the durability test satisfy, for example, the relationship of |Rp - Rb| / Rb ≤ 5%. In other words, the change rate of the sheet resistance of the transparent conductive film 3 before and after the durability test is, for example, 5% or less. The durability test is performed, for example, by holding the transparent conductive film 3 for 1000 hours under the conditions of a temperature of 85°C and a relative humidity of 85%. The sheet resistance of the transparent conductive film 3 in a high-temperature and high-humidity environment hardly changes, and the transparent conductive film 3 can exhibit high durability in a high-temperature and high-humidity environment. It should be noted that the conditions of the environment of the transparent conductive film 3 in the durability test are just an example. For example, even if the transparent conductive film 3 is subjected to a durability test under other conditions commonly required in the fields such as information terminals with touch panels such as smartphones and in-vehicle devices such as heaters, the relationship of |Rp - Rb| / Rb ≤ 5% can be satisfied. For example, for the transparent conductive film 3, even if the durability test is performed in a high-temperature and low-humidity environment, a low-temperature and high-humidity environment, and a low-temperature and low-humidity environment, the relationship of |Rp - Rb| / Rb ≤ 5% can be satisfied.

[0042] The average value Df can be 170 nm or more, can be 180 nm or more, can be 190 nm or more, or can be 200 nm or more. The average value Df can be 350 nm or less, can be 330 nm or less, can be 300 nm or less, can be 280 nm or less, or can be 250 nm or less.

[0043] The transparent conductive film 3, for example, keeps the water vapor transmission rate Ws of a specified laminate determined according to ISO 15106-5:2015 at 0.0010 g / (m 2 ·24 h) to 0.0250 g / (m 2 ·24 h). The specified laminate is a laminate in which the transparent conductive film 3 is disposed on a support material. In addition, the water vapor transmission rate of this support material determined according to ISO 15106-5:2015 is 1 g / (m 2 ·24 h) or more. In this case, the transparent conductive film 3 can keep the water vapor transmission rate of the laminate produced by disposing the transparent conductive film 3 on the support material having a high water vapor transmission rate at a low level. Therefore, even when there is no gas barrier layer near the transparent conductive film 3, the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment. It should be noted that this laminate is produced to indirectly evaluate the water vapor permeability of the transparent conductive film 3. When producing the laminate 1, the support material is not overlapped with the base material 2 in a state where the transparent conductive film 3 is formed on the support. When producing the laminate 1, typically, the transparent conductive film 3 is separately formed on the base material 2. The support material in this laminate and the base material 2 in the laminate 1 may be the same or different. In other words, the value of the water vapor transmission rate of the base material 2 determined according to ISO15106-5:2015 is not limited to the range of 1 g / (m 2 ·24 h) or more. The value of the water vapor transmission rate of the base material 2 can be less than 1 g / (m 2 ·24 h). In this laminate, the support material and the transparent conductive film 3 occupy different spaces and are clearly distinguished from the transparent conductive film 3.

[0044] According to the transparent conductive film 3, the water vapor transmission rate Ws is preferably kept at 0.0010 g / (m 2 ·24 h) to 0.0200 g / (m 2 ·24 h), more preferably kept at 0.0010 g / (m 2 ·24 h) to 0.0150 g / (m 2 ·24 h), and further preferably kept at 0.0010 g / (m 2 ·24 h) to 0.0120 g / (m 2· (per 24 hours). The water vapor transmission rate Ws can be 0.005 g / (m 2 ·24 hours) or more, and can also be 0.008 g / (m 2 ·24 hours) or more.

[0045] The material forming the polycrystal 31 in the transparent conductive film 3 is not particularly limited. The polycrystal 31 contains, for example, indium oxide. Thus, the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment.

[0046] In the transparent conductive film 3, the polycrystal 31 preferably contains indium oxide as a main component. This is advantageous from the viewpoint of the transparent conductive film 3 exhibiting high durability in a high-temperature and high-humidity environment. In the present specification, the "main component" means the component with the highest content based on the mass basis.

[0047] In the transparent conductive film 3, the polycrystal 31 preferably contains indium tin oxide (ITO). Thus, the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment. The content of tin oxide in ITO is, for example, 3 wt% to 14 wt%, preferably 5 wt% to 13 wt%.

[0048] The density d of the transparent conductive film 3 is not limited to a specific value. The density d is, for example, 7.15 g / cm 3 or more. In this case, in the polycrystal 31, the gaps between the crystal grains 32 are likely to become smaller. As a result, water vapor is difficult to permeate through the transparent conductive film 3, and the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment.

[0049] The density d can be 7.20 g / cm 3 or more, and can also be 7.30 g / cm 3 or more. The density d is, for example, 7.50 g / cm 3 or less. Thus, cracks are difficult to occur in the transparent conductive film 3, and the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment. The density d can also be 7.40 g / cm 3 or less.

[0050] The thickness t of the transparent conductive film 3 is not limited to a specific value. Regarding the thickness t, for example, it has a thickness of 20 nm to 150 nm. By the thickness t being 20 nm or more, the transparent conductive film 3 easily has a desired sheet resistance. On the other hand, by the thickness t being 150 nm or less, cracks are difficult to occur in the transparent conductive film 3, and the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment.

[0051] The thickness t can be 25 nm or more, can be 35 nm or more, or can be 45 nm or more. The thickness t can be 140 nm or less, can be 130 nm or less, or can be 120 nm or less.

[0052] The internal stress Pi of the transparent conductive film determined by X-ray stress measurement method is not limited to a specific value. The internal stress Pi is, for example, 150 MPa to 1000 MPa. When the internal stress Pi is 100 MPa or more, in the polycrystal 31, the gaps between the crystal grains 32 are likely to become smaller. As a result, water vapor is difficult to permeate through the transparent conductive film 3, and the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment. On the other hand, when the internal stress Pi is 1000 MPa or less, cracks are less likely to occur in the transparent conductive film 3, and the transparent conductive film 3 can more reliably exhibit high durability in a high-temperature and high-humidity environment. The internal stress Pi can be measured, for example, according to the method described in the examples.

[0053] The internal stress Pi can be 160 MPa or more, can be 180 MPa or more, can be 200 MPa or more, or can be 300 MPa or more. The internal stress Pi can be 950 MPa or less, can be 900 MPa or less, or can be 800 MPa or less.

[0054] In the laminate 1, the substrate 2 is not limited to a specific substrate. In particular, the water vapor transmission rate Wk of the substrate 2 determined according to ISO15106-5:2015 is not limited to a specific value. The water vapor transmission rate Wk is, for example, 1 g / (m 2 ·24 h) or more. The water vapor transmission rate Wk can also be less than 1 g / (m 2 ·24 h).

[0055] The substrate 2 is, for example, transparent to visible light. Thus, the laminate 1 can also be transparent to visible light. The laminate 1 can also be transparent to light with a specified wavelength such as near-infrared light.

[0056] The material of the substrate 2 is not limited to a specific material. The substrate 2 contains, for example, an organic material such as an organic polymer. Thus, the substrate 2 is likely to have flexibility. The substrate 2 can contain, for example, at least one organic polymer selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, polyether ether ketone, and aromatic polyamide. The substrate 2 can also contain an inorganic material such as glass. In this case, the laminate 1 is likely to have high rigidity. The substrate 2 can be a mixture of an organic material and an inorganic material, or can be a composite material.

[0057] For example, in the laminate 1, the substrate 2 is in contact with the transparent conductive film 3. The main surface 21 of the substrate 2 that forms an interface with the transparent conductive film 3 can be formed of a gas-barrier material or can be formed of a material that does not have gas-barrier properties.

[0058] The thickness T of the base material 2 is not limited to a specific value. From the viewpoints of good transparency, good strength, and ease of handling, the thickness T is, for example, 10 μm to 2 mm. The thickness T can be 20 μm or more, can be 30 μm or more, and can also be 50 μm or more. The thickness T can be 1.8 mm or less, can be 1.5 mm or less, can be 1.0 mm or less, can be 500 μm or less, can be 300 μm or less, and can also be 200 μm or less.

[0059] An example of a method for manufacturing the transparent conductive film 3 will be described. The transparent conductive film 3 is manufactured, for example, by a method including the following steps (i) and (ii).

[0060] (i) A film is formed on the base material 2 by sputtering.

[0061] (ii) The film is annealed to form the transparent conductive film 3.

[0062] In the sputtering in step (i), the pressure Pf of the inert gas is adjusted to 0.4 Pa or less. Conventionally, it has been considered that when forming a transparent conductive film by sputtering, a low pressure of the inert gas makes the internal stress of the transparent conductive film high and causes deformation of the base material, and thus is disadvantageous. However, based on the trial and error of the present inventors, it has been found that in the sputtering for forming a transparent conductive film, adjusting the pressure Pf to 0.4 Pa or less is advantageous for manufacturing a transparent conductive film that exhibits high durability in a high-temperature and high-humidity environment. It is considered that in the sputtering for forming a transparent conductive film, if the pressure Pf is adjusted to 0.4 Pa or less, the ionic particles collide with the base material 2 while maintaining a high energy state as they are. It is considered that thereby, the average value Df of the maximum Feret diameter of the crystal grains 32 is easily adjusted to the range of 160 nm to 400 nm.

[0063] The pressure Pf can be 0.35 Pa or less, and can also be 0.3 Pa or less. The pressure Pf is, for example, 0.05 Pa or more, can be 0.07 Pa or more, and can also be 0.1 Pa or more.

[0064] The method of sputtering in step (i) is not limited to a specific method. The method of sputtering in step (i) is, for example, a high magnetic field DC magnetron sputtering method. Thereby, the transparent conductive film 3 that more reliably exhibits high durability in a high-temperature and high-humidity environment can be manufactured.

[0065] By the annealing in step (ii), crystallization in the film formed in step (i) is promoted. As a result, polycrystals 31 in a desired state can be obtained in the transparent conductive film 3.

[0066] (ii) The ambient temperature Tk of the substrate 2 during the annealing in the step is not limited to a specific value. The ambient temperature Tk is, for example, 165°C or higher. Thereby, the substrate 2 is liable to shrink after annealing, and the internal stress of the transparent conductive film 3 is liable to become high. As a result, the transparent conductive film 3 that can exhibit high durability more reliably in a high-temperature and high-humidity environment can be manufactured.

[0067] The ambient temperature Tk can be 170°C or higher, and can also be 175°C or higher. The ambient temperature Tk is, for example, 185°C or lower. Thereby, cracks are difficult to occur in the transparent conductive film 3.

[0068] (ii) The annealing time Ha in the step is not limited to a specific value. The time Ha is, for example, 90 minutes or less. The time Ha can be 60 minutes or less. The time Ha is, for example, 15 minutes or more. Thereby, polycrystals 31 in a desired state can be obtained in the transparent conductive film 3.

[0069] The transparent conductive film 3 can also be formed by methods such as vacuum evaporation or ion plating instead of sputtering.

[0070] The laminate 1 can be used, for example, in fields such as touch panels for information terminals and heaters. For example, using the laminate 1 can provide Figure 3 the heater 10a shown. The heater 10a has the laminate 1 and a pair of power feeding electrodes 4. The pair of power feeding electrodes 4 is electrically connected to the transparent conductive film 3. The pair of power feeding electrodes 4 can be connected to a power source (not shown). In the present specification, the pair of power feeding electrodes 4 refers to a pair of a positive electrode and a negative electrode. When one of the pair of power feeding electrodes 4 functions as a positive electrode, the other of the pair of power feeding electrodes 4 functions as a negative electrode. Electric power from the power source is supplied to the transparent conductive film 3 through the pair of power feeding electrodes 4, whereby the transparent conductive film 3 generates heat.

[0071] The power feeding electrode 4 has, for example, a thickness of 1 μm or more. Thereby, when the heater 1a operates at a high heating rate, the power feeding electrode 4 is difficult to be damaged. It should be noted that the thickness of this power feeding electrode 4 is significantly larger than the thickness of the electrode formed on the transparent conductive film used in display devices such as touch panels. The thickness of the power feeding electrode 4 can be 2 μm or more, can be 3 μm or more, and can also be 5 μm or more. The thickness of the power feeding electrode 4 is, for example, 5 mm or less, can be 1 mm or less, and can also be 700 μm or less.

[0072] A pair of power feeding electrodes 4 are formed, for example, in the following manner. A seed layer is formed on the main surface of the transparent conductive film 3 by a dry process such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) or a plating method. Next, a masking mask is disposed on the seed layer where the power feeding electrodes 4 should not be formed. The masking mask can be fabricated by laminating a resist on the seed layer and then subjecting it to an exposure and development process. Then, a metal film of 1 μm or more is formed on the portion where the masking film is not disposed by a wet process such as a plating method. Next, the masking film disposed on the seed layer is removed, and a masking film formed using a resist is used to cover the metal film where the power feeding electrodes 4 are to be formed. Next, the seed layer exposed by etching is removed. Then, the masking film is removed, whereby a pair of power feeding electrodes 4 can be formed.

[0073] A pair of power feeding electrodes 4 can also be formed in the following manner. First, as described above, a seed layer is formed on the main surface of the transparent conductive film 3. Then, a metal film of 1 μm or more is formed on the main surface of the transparent conductive film 3 by a dry process such as CVD and PVD or a wet process such as a plating method. Next, a part of the metal film where the power feeding electrodes 4 are to be formed is covered with a masking mask formed using a resist. Then, the unnecessary metal film is removed by etching, and the masking mask is removed. Thereby, a pair of power feeding electrodes 4 are formed. In addition, the power feeding electrodes 4 can be formed by coating a conductive ink in a predetermined pattern on the main surface of the transparent conductive film 3 and curing the coated conductive ink. The power feeding electrodes 4 can also be formed by coating a conductive paste in a predetermined pattern on the main surface of the transparent conductive film 3 by a coating method such as coating with a dispenser and screen printing and curing the coated conductive paste. The conductive paste typically contains a filler of a conductive material such as silver. The power feeding electrodes 4 can be formed using a solder paste.

[0074] The heater 10a can be changed in consideration of various viewpoints. For example, the heater 10a can be changed like the heater 10b Figure 4 shown. Except in the case of special description, the heater 10b is configured in the same manner as the heater 10a. The constituent elements of the heater 10b that are the same as or corresponding to the constituent elements of the heater 10a are denoted by the same reference numerals, and detailed description thereof is omitted. As long as there is no technical contradiction, the description related to the heater 10a also applies to the heater 10b.

[0075] As Figure 4As shown, the heater 10b has a protective layer 5. The protective layer 5 is configured such that the transparent conductive film 3 is located between the protective layer 5 and the substrate 2. The protective layer 5 has, for example, a prescribed protective film and an adhesive layer for pasting the protective film onto the transparent conductive film 3. The transparent conductive film 3 is protected by the protective layer 5, and the heater 10b has high impact resistance. The material of the protective film in the protective layer 5 is not particularly limited, and is, for example, a synthetic resin such as a fluororesin, polysiloxane, acrylic resin, and polyester. The thickness of the protective film is not limited to a specific value, and is, for example, 20 μm to 200 μm. Thereby, while the heater 10b has good impact resistance, it is possible to prevent the thickness of the heater 10b from becoming too large. The adhesive layer is formed of a known adhesive such as an acrylic adhesive, for example. For example, when the protective film itself has adhesiveness, the protective layer 5 can also be formed only using the protective film.

[0076] The heater 10a or 10b can be used to produce an article with a heater. For example, as Figure 5 shown, the article with a heater 100 has a molded body 7, an adhesive layer 6, and a heater 10a. The molded body 7 has an adherend surface 71. The molded body 7 is formed of a metallic material, glass, or synthetic resin. The adhesive layer 6 is in contact with the adherend surface 71. The adhesive layer 6 is formed of a known adhesive such as an acrylic adhesive, for example. The heater 10a is in contact with the adhesive layer 6 and is mounted on the molded body 7 through the adhesive layer 6.

[0077] The adhesive layer 6 can be formed in advance on the main surface of the substrate 2, for example. In this case, by opposing the adhesive layer 6 to the adherend surface 71 and pressing the heater 10a against the molded body 7, the heater 10a can be mounted on the molded body 7. Further, the adhesive layer 6 can be covered with a separator (not shown). In this case, when the heater 10a is mounted on the molded body 7, the separator is peeled off to expose the adhesive layer 6. The separator 6 is a film made of a polyester resin such as polyethylene terephthalate (PET), for example.

[0078] The heater 10a is arranged on the optical path of the near-infrared rays in a device that performs a process using near-infrared rays, for example. The device performs a prescribed process such as sensing or communication using near-infrared rays, for example. The molded body 7 constitutes the housing of such a device, for example.

[0079] Examples

[0080] Hereinafter, the present invention will be described in more detail by way of examples. It should be noted that the present invention is not limited to the following examples. First, the evaluation methods and measurement methods related to the examples and comparative examples will be described.

[0081] [Determination of the average value of the maximum Feret diameter of crystal grains]

[0082] The laminates of the examples and comparative examples were cut into squares with sides of 300 μm, thereby obtaining fragments. The fragments were fixed to the specimen holder of an ultramicrotome with the film surface of the transparent conductive film facing the operator. The knife was set such that the tip of the knife was on a plane forming a very small acute angle (3° or less) with respect to the film surface of the transparent conductive film in the fragment. Then, using the knife, the fragment was cut to a thickness of 70 nm, thereby obtaining a section. The knife was set such that a section having a target observation site of 3 μm square or more was obtained.

[0083] Using a transmission electron microscope JEM-2800 manufactured by JEOL Ltd., the film surface of the transparent conductive film in the TEM observation specimen prepared from the section was observed. Based on the contrast difference between adjacent crystal grains in fields of view of 400 nm square randomly selected from 10 or more locations in the TEM photograph of the film surface, the boundaries between the crystal grains were determined. Then, based on the determined boundaries between the crystal grains, the maximum Feret diameter of each crystal grain contained in each field of view was determined. This determination was performed for crystal grains that could be observed as a whole in each field of view. Based on the determined maximum Feret diameters of the respective crystal grains, the average value Df of the maximum Feret diameters of the crystal grains was determined by arithmetic mean. The results are shown in Table 1. It should be noted that in the determination of the average value Df of the maximum Feret diameter, the values of the maximum Feret diameters of 10 or more crystal grains were used.

[0084] [Measurement of water vapor transmission rate]

[0085] Using a water vapor transmission rate measuring device DELTAPERM, the water vapor transmission rate of the water vapor transmission rate test pieces prepared from the laminates of the examples and comparative examples was measured in accordance with ISO 15106-5:2015. In this measurement, the temperature of the upstream chamber was adjusted to 40 °C and the relative humidity was adjusted to 90%, and the pressure of the upstream chamber was adjusted to 50 Torr. In addition, in this measurement, the transparent conductive film was in contact with the downstream chamber. In this measurement, if the pressure in the downstream chamber was greater than 1 Torr, the vacuum pump was operated for evacuation. The water vapor transmission rate determined from the results of this measurement is shown in Table 1. The water vapor transmission rate of the base materials used in the examples and comparative examples was measured in the same manner as for the laminates. The results are shown in Table 1.

[0086] [Measurement of the thickness of the transparent conductive film]

[0087] Using an X-ray diffractometer (manufactured by Rigaku Corporation, product name: RINT2200), the thickness of the transparent conductive film of the laminates of each example and each comparative example was measured by the X-ray reflectivity method. The results are shown in Table 1.

[0088] [Density of the transparent conductive film]

[0089] The density of the transparent conductive film of the laminate of each example and each comparative example was measured by the X-ray reflectivity method. The results are shown in Table 1.

[0090] [Internal Stress of Transparent Conductive Film]

[0091] Using an X-ray diffractometer (manufactured by Rigaku Corporation, product name: RINT2200), Cu-Kα rays (wavelength λ: 0.1541 nm) from a light source of 40 kV and 40 mA were passed through a parallel beam optical system and then irradiated onto the specimen, and the internal stress (compressive stress) of the transparent conductive film was evaluated using the principle of the sin 2 Ψ method. The sin 2 Ψ method is a method for obtaining the internal stress of a thin film based on the dependence of the lattice strain of a polycrystalline thin film on the angle (Ψ). Using the above X-ray diffractometer, through θ / 2θ scanning measurement, the diffraction intensity was measured every 0.02° in the range of 2θ = 29.8° to 31.2°. The cumulative time for each measurement point was set to 100 seconds. The lattice spacing d of ITO at each measurement angle (Ψ) was calculated from the peak angle 2θ of the obtained X-ray diffraction (peak of the (222) plane of ITO) and the wavelength λ of the X-ray irradiated from the light source, and the lattice strain ε was calculated from the lattice spacing d according to the relationship of the following formulas (1) and (2). λ is the wavelength of the X-ray (Cu-Kα ray) irradiated from the light source, λ = 0.1541 nm. d0 is the lattice spacing of ITO in a stress-free state, d0 = 0.2910 nm. The value of d0 is the value recorded in the database of the International Centre for Diffraction Data (ICDD).

[0092] 2dsinθ = λ Formula (1)

[0093] ε = (d - d0) / d0 Formula (2)

[0094] As Figure 6 shown, when the angles (Ψ) formed by the normal of the main surface of the transparent conductive film with respect to the specimen Sa and the normal of the crystal plane of the ITO crystal Cr are 45°, 52°, 60°, 70°, and 90°, respectively, the above X-ray diffraction measurement was performed, and the lattice strain ε at each angle (Ψ) was calculated. Then, the in-plane residual stress (internal stress) σ of the transparent conductive film was obtained by the slope of the straight line obtained by plotting the relationship between sin 2 Ψ and the lattice strain ε through the following formula (3). The results are shown in Table 1.

[0095] ε = {(1 + ν) / E}σsin 2 Ψ - (2ν / E)σ Formula (3)

[0096] In the above formula (3), E is the Young's modulus of ITO (116 GPa), and ν is the Poisson's ratio (0.35). Their values are the values described in D.G. Neerinck and T.J. Vink, "Depth Profiling of thin ITO films by grazing incidence X-ray diffraction", Thin Solid Films, 278 (1996), pages 12 - 17. In Figure 6 the detector 100 detects X-ray diffraction.

[0097] [Durability test]

[0098] Durability tests were conducted on test pieces made from the laminates of the examples and comparative examples. In the durability test, the test pieces were placed in an environment with a temperature of 85 °C and a relative humidity of 85% for 1000 hours. Using a non-contact resistance measuring device (manufactured by Napson Corporation, product name: NC-80MAP), in accordance with JIS Z 2316-1:2014, the sheet resistance of the transparent conductive film of each test piece before and after the durability test was measured by eddy current measurement. From the measurement results, the value of |Rp - Rb| / Rb was obtained for each test piece. Here, Rp is the value of the sheet resistance of the transparent conductive film after the durability test, and Rb is the value of the sheet resistance of the transparent conductive film before the durability test. Test pieces that satisfied |Rp - Rb| / Rb ≤ 5% were evaluated as "A", and the other test pieces were evaluated as "X". The results are shown in Table 1.

[0099] <Example 1>

[0100] Indium tin oxide (ITO) (tin oxide content: 10% by weight) was used as the target, and in the presence of an inert gas, an ITO film was formed on a poly(ethylene naphthalate) (PEN) film with a thickness of 125 μm by DC magnetron sputtering. Argon was used as the inert gas, and the pressure of argon was adjusted to 0.2 Pa. The PEN film after forming the ITO film was placed in the atmosphere at 180 °C for 1 hour for annealing treatment. Thus, the ITO was crystallized to form a transparent conductive film. Thus, the laminate of Example 1 was obtained. The conditions of the DC magnetron sputtering method were adjusted so that the thickness of the transparent conductive film was 50 nm. The TEM photograph of the film surface of the transparent conductive film of the laminate of Example 1 is shown in Figure 7A in. Based on Figure 7A the boundaries between the grains determined are shown in Figure 7B in.

[0101] <Example 2>

[0102] The conditions of the DC magnetron sputtering method were adjusted such that the thickness of the transparent conductive film was 100 nm, and the laminate of Example 2 was obtained in the same manner as in Example 1 except for this.

[0103] <Example 3>

[0104] A film of polyethylene terephthalate (PET) with a thickness of 125 μm was used instead of the PEN film, and the laminate of Example 3 was obtained in the same manner as in Example 1 except for this.

[0105] <Example 4>

[0106] A film of PET with a thickness of 125 μm was used instead of the PEN film, and the annealing treatment conditions were changed to the condition of being placed in the atmosphere at 160 °C for 1 hour. The laminate of Example 4 was obtained in the same manner as in Example 1 except for this.

[0107] <Example 5>

[0108] The conditions of the DC magnetron sputtering method were adjusted such that the thickness of the transparent conductive film was 30 nm, and the laminate of Example 5 was obtained in the same manner as in Example 1 except for this.

[0109] <Comparative Example 1>

[0110] In the DC magnetron sputtering method, the pressure of argon was changed to 0.45 Pa, and the PEN film after forming the ITO film was annealed by being placed in the atmosphere at 150 °C for 3 hours. The laminate of Comparative Example 1 was obtained in the same manner as in Example 1 except for this. The TEM photograph of the film surface of the transparent conductive film of the laminate of Comparative Example 1 is shown in Figure 8A in. The boundaries between grains determined based on Figure 8A are shown in Figure 8B in.

[0111] <Comparative Example 2>

[0112] In the DC magnetron sputtering method, the pressure of argon was changed to 1.0 Pa, and the laminate of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except for this.

[0113] <Comparative Example 3>

[0114] Annealing treatment was not performed, and the laminate of Comparative Example 3 was obtained in the same manner as in Comparative Example 1 except for this. The transparent conductive film of the laminate of Comparative Example 3 was amorphous.

[0115] As shown in Table 1, the change rate of the sheet resistance of the transparent conductive films of the laminates of Examples 1 to 5 before and after the durability test was small, indicating good durability in a high-temperature and high-humidity environment. On the other hand, the change rate of the sheet resistance of the transparent conductive films of the laminates of Comparative Examples 1 to 3 before and after the durability test was large, and it was difficult to say that the durability in a high-temperature and high-humidity environment was good. In the transparent conductive films of the laminates of Examples 1 to 5, the average value of the maximum Feret diameter of the crystal grains was in the range of 160 nm to 400 nm, indicating that this was advantageous from the viewpoint of durability in a high-temperature and high-humidity environment.

[0116] As shown in Table 1, the internal stress of the transparent conductive films in the laminates of Examples 1, 2, and 5 was in the range of 100 MPa to 500 MPa. On the other hand, the internal stress of the transparent conductive films in the laminates of Examples 3 and 4 was greater than the internal stress of the transparent conductive films in the laminates of Examples 1, 2, and 5. This implies that, when using a PET film as the substrate, compared with the case of using a PEN film as the substrate, the shrinkage after annealing treatment is likely to be larger, and the internal stress of the transparent conductive film is likely to be larger.

[0117]

Claims

1. A transparent conductive film, wherein, The transparent conductive film has polycrystals, and the polycrystals have grains with an average maximum Feret diameter of 160 nm to 400 nm. The transparent conductive film maintains a water vapor transmission rate of 0.0010 g / (m 2 24 hours)~0.0250g / (m 2 24 hours), The water vapor transmission rate of the support material determined according to ISO 15106-5:2015 is 1 g / (m 2 ·24 h) or more.

2. The transparent conductive film according to claim 1, wherein, The polycrystals contain indium oxide.

3. The transparent conductive film according to claim 1, wherein, The transparent conductive film has a density of 7.15 g / cm 3 or more.

4. The transparent conductive film according to claim 1, wherein, The transparent conductive film has a thickness of 20 nm to 150 nm.

5. The transparent conductive film according to claim 1, wherein The internal stress of the transparent conductive film determined by X-ray stress measurement is 150 MPa to 1000 MPa.

6. A laminated body, wherein: The laminate has: a substrate, and the transparent conductive film according to any one of claims 1 to 5 disposed on the substrate.

7. The laminate according to claim 6, wherein, The water vapor transmission rate of the substrate determined according to ISO 15106-5:2015 is 1 g / (m 2 24 hours or more.

8. A method for manufacturing the transparent conductive film according to any one of claims 1 to 5, wherein, The method for manufacturing the transparent conductive film includes: forming a film on a substrate by sputtering; and annealing the film to form a polycrystalline transparent conductive film, and in the sputtering, adjusting the pressure of the inert gas to 0.4 Pa or less.

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