JP7425266B2 - transparent conductive film - Google Patents

Description

The present invention relates to transparent conductive films.

2. Description of the Related Art Conventionally, transparent conductive films are known that include a transparent base film made of resin and a transparent conductive layer (transparent conductive layer) in order in the thickness direction. A transparent conductive layer is used, for example, as a conductive film for forming transparent electrodes in various devices such as liquid crystal displays, touch panels, and solar cells. The transparent conductive layer is formed, for example, by depositing a conductive oxide on a base film using a sputtering method. Techniques regarding such transparent conductive films are described, for example, in Patent Document 1 below.

JP2017-71850A

A conventional transparent conductive film is manufactured, for example, as follows. First, an amorphous transparent conductive layer is formed on a base film in a film forming chamber of a sputter film forming apparatus. Next, the transparent conductive layer on the base film is heated in a hot air heating oven. By this heating, the transparent conductive layer is converted from amorphous to crystalline (crystallization step). The higher the heating temperature, the higher the crystallinity of the formed crystalline transparent conductive layer, and the lower the resistance value of the layer.

If the heating temperature in the crystallization step is too high, problems such as dimensional changes and deformation occur in the resin base film. Therefore, in the crystallization step, it is necessary to heat the transparent conductive layer at a temperature that does not cause such problems (a temperature that is not too high).

However, when a conventional transparent conductive film having a transparent conductive layer crystallized in the above-mentioned crystallization process undergoes a relatively high temperature heating process in the manufacturing process of a device equipped with the same film, the resistance of the transparent conductive layer may rise. An increase in the resistance value of the transparent conductive layer in the transparent conductive film after manufacture is undesirable because it affects the performance of the device.

The present invention provides a transparent conductive film suitable for suppressing an increase in the resistance value of a transparent conductive layer due to heating during the device manufacturing process.

The present invention [1] is a transparent conductive film comprising a transparent resin base material and a crystalline transparent conductive layer in this order in the thickness direction, wherein the transparent conductive layer has an atomic number larger than that of argon. Containing rare gas atoms, the transparent conductive layer has a first resistance value R1 (Ω/□), and a second resistance value R2 (Ω/□) after heat treatment at 160° C. for 30 minutes. , and the ratio of the second resistance value R2 to the first resistance value R1 is 0.650 or more and 0.990 or less.

The present invention [2] includes the transparent conductive film according to the above [1], wherein the transparent conductive layer includes an indium tin composite oxide layer with a tin oxide content of less than 10% by mass.

The present invention [3] includes the transparent conductive film according to the above [1] or [2], wherein the transparent conductive layer has a thickness of 150 nm or less.

The present invention [4] includes the transparent conductive film according to any one of [1] to [3] above, wherein the first resistance value R1 is 220Ω/□ or less.

As described above, in the transparent conductive film of the present invention, the crystalline transparent conductive layer contains rare gas atoms having an atomic number larger than argon, and the transparent conductive layer is heated at 160° C. for 30 minutes. The ratio (R2/R1) of the second resistance value R2 after the heat treatment to the first resistance value R1 (before the heat treatment) is 0.650 or more and 0.990 or less. In the transparent conductive film, the second resistance value R2 after heat treatment (160° C., 30 minutes) is appropriately smaller than the first resistance value R1 before heat treatment. Such a transparent conductive film is suitable for suppressing an increase in the resistance value of the transparent conductive layer due to heating during the device manufacturing process.

1 is a schematic cross-sectional view of an embodiment of a transparent conductive film of the present invention. A case where the transparent conductive layer includes multiple layers is shown. The method for manufacturing the transparent conductive film shown in FIG. 1 is shown. 3A represents a process of preparing a resin film, FIG. 3B represents a process of forming a functional layer on the resin film, FIG. 3C represents a process of forming a transparent conductive layer on the functional layer, and FIG. 3D represents a process of forming a transparent conductive layer on the functional layer. represents the process of crystallizing the transparent conductive layer. In the transparent conductive film shown in FIG. 1, the transparent conductive layer is patterned.

A transparent conductive film X as an embodiment of the transparent conductive film of the present invention includes a transparent resin base material 10 and a transparent conductive layer 20 in this order in the thickness direction D. The transparent conductive film X has a sheet shape that spreads in a direction (plane direction) orthogonal to the thickness direction D. The transparent conductive film X is an element included in a touch sensor device, a light control element, a photoelectric conversion element, a heat ray control member, an antenna member, an electromagnetic shielding member, a heater member, a lighting device, an image display device, and the like.

In this embodiment, the transparent resin base material 10 includes a resin film 11 and a functional layer 12 in this order in the thickness direction D.

The resin film 11 is a base material that ensures the strength of the transparent conductive film X. Further, the resin film 11 is a transparent resin film having flexibility. Examples of the material for the resin film 11 include polyester resin, polyolefin resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Polyolefin resins include, for example, polyethylene, polypropylene, and cycloolefin polymers. Examples of the acrylic resin include polymethacrylate. As the material for the resin film 11, for example, from the viewpoint of transparency and strength, polyester resin is preferably used, and PET is more preferably used.

The surface of the resin film 11 on the functional layer 12 side may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

From the viewpoint of ensuring the strength of the transparent conductive film X, the thickness of the resin film 11 is preferably 1 μm or more, more preferably 10 μm or more, and still more preferably 30 μm or more. The thickness of the resin film 11 is preferably 500 μm or less, more preferably 300 μm or less, still more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably is 75 μm or less.

The total light transmittance (JIS K 7375-2008) of the resin film 11 is preferably 60% or more, more preferably 80% or more, and even more preferably 85% or more. Such a configuration is applicable when the transparent conductive film It is suitable for ensuring the transparency required for the transparent conductive film X. The total light transmittance of the resin film 11 is, for example, 100% or less.

The functional layer 12 is arranged on one side of the resin film 11 in the thickness direction D. In this embodiment, the functional layer 12 is in contact with the resin film 11. Furthermore, in this embodiment, the functional layer 12 is a hard coat layer for making it difficult for scratches to be formed on the exposed surface (the upper surface in FIG. 1) of the transparent conductive layer 20.

The hard coat layer is a cured product of a curable resin composition. The curable resin composition contains a curable resin. Examples of the curable resin include polyester resin, acrylic urethane resin, acrylic resin (excluding acrylic urethane resin), urethane resin (excluding acrylic urethane resin), amide resin, silicone resin, epoxy resin, and melamine resin. . These curable resins may be used alone or in combination of two or more. From the viewpoint of ensuring high hardness of the hard coat layer, at least one selected from the group consisting of acrylic urethane resins and acrylic resins is preferably used as the curable resin.

Furthermore, examples of the curable resin include ultraviolet curable resins and thermosetting resins. The curable resin is preferably an ultraviolet curable resin, since it can be cured without high-temperature heating and is useful for improving the manufacturing efficiency of the transparent conductive film X.

The curable resin composition may contain particles. Examples of the particles include inorganic oxide particles and organic particles. Examples of the material for the inorganic oxide particles include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of the material for the organic particles include polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate.

The surface of the functional layer 12 on the transparent conductive layer 20 side may be subjected to surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

The thickness of the functional layer 12 as a hard coat layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, from the viewpoint of developing sufficient scratch resistance in the transparent conductive layer 20. be. From the viewpoint of ensuring transparency of the functional layer 12, the thickness of the functional layer 12 as a hard coat layer is preferably 20 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less, particularly preferably 3 μm or less.

The thickness of the transparent resin base material 10 is preferably 1 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, particularly preferably 30 μm or more. The thickness of the transparent resin base material 10 is preferably 520 μm or less, more preferably 320 μm or less, even more preferably 220 μm or less, even more preferably 120 μm or less, particularly preferably 80 μm or less. These configurations regarding the thickness of the transparent resin base material 10 are suitable for ensuring ease of handling of the transparent conductive film X.

The total light transmittance (JIS K 7375-2008) of the transparent resin base material 10 is preferably 60% or more, more preferably 80% or more, and still more preferably 85% or more. Such a configuration is applicable when the transparent conductive film It is suitable for ensuring the transparency required for the transparent conductive film X. The total light transmittance of the transparent resin base material 10 is, for example, 100% or less.

The transparent conductive layer 20 is arranged on one side of the transparent resin base material 10 in the thickness direction D. In this embodiment, the transparent conductive layer 20 is in contact with the transparent resin base material 10. The transparent conductive layer 20 is a crystalline film that has both light transparency and conductivity. Such a transparent conductive layer 20 is made of, for example, a conductive oxide. The fact that the transparent conductive layer 20 is a crystalline film is suitable for suppressing large fluctuations in the resistance value of the transparent conductive layer 20 due to subsequent heating.

Whether the transparent conductive layer (transparent conductive layer 20 on the transparent resin base material 10 in transparent conductive film X) is a crystalline film can be determined by planar observation of the transparent conductive layer using a transmission electron microscope (TEM). . In planar observation of a transparent conductive layer using a TEM, if crystal grains are observed without an amorphous region, it can be determined that the transparent conductive layer is a crystalline film. In preparing a sample for planar observation of a transparent conductive layer in a transparent conductive film, after fixing the transparent conductive film to the sample holder of an ultramicrotome, a microtome knife is placed at an extremely acute angle to the transparent conductive layer. The transparent conductive layer is cut with the knife so as to be substantially parallel to the exposed surface of the transparent conductive layer. Thereby, a transparent conductive layer sample as a sample for planar observation can be obtained.

The fact that the transparent conductive layer is a crystalline film can also be determined by observing the cross section of the transparent conductive layer using a field emission transmission electron microscope (FE-TEM). When observing a cross section of a transparent conductive layer using FE-TEM, if crystal grains are observed without an amorphous region, it can be determined that the transparent conductive layer is a crystalline film. A method for confirming that the transparent conductive layer is a crystalline film using FE-TEM will be specifically described later in connection with Examples.

Whether the transparent conductive layer is a crystalline film can also be determined, for example, by the following method. First, the transparent conductive layer is immersed in hydrochloric acid having a concentration of 5% by mass at 20° C. for 15 minutes. Next, the transparent conductive layer is washed with water and then dried. Next, on the exposed plane of the transparent conductive layer (in the transparent conductive film resistance). In this measurement, if the inter-terminal resistance is 10 kΩ or less, it can be determined that the transparent conductive layer is a crystalline film.

Examples of the conductive oxide include indium-containing conductive oxides and antimony-containing conductive oxides. Examples of indium-containing conductive oxides include indium tin composite oxide (ITO), indium zinc composite oxide (IZO), indium gallium composite oxide (IGO), and indium gallium zinc composite oxide (IGZO). It will be done. Examples of the antimony-containing conductive oxide include antimony tin composite oxide (ATO). From the viewpoint of achieving high transparency and good electrical conductivity, an indium-containing conductive oxide is preferably used as the conductive oxide, and ITO is more preferably used. This ITO may contain a metal or metalloid other than In and Sn in an amount smaller than the respective contents of In and Sn.

The transparent conductive layer 20 (crystalline) preferably includes an indium tin composite oxide layer (first ITO layer) with a tin oxide content of less than 10% by mass. Specifically, the tin oxide ratio in the ITO layer is the ratio of the tin oxide content to the total content of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) in the ITO forming the same layer. . The transparent conductive layer 20 including the first ITO layer is crystallized by heating the transparent conductive layer 20' after the amorphous transparent conductive layer 20' including the first ITO layer is formed, as described later. formed by The fact that the transparent conductive layer 20 includes the first ITO layer is suitable for forming an amorphous transparent conductive layer (transparent conductive layer 20' to be described later) in which an increase in resistance value due to heating after crystallization is suppressed. .

From the viewpoint of ensuring the durability of the transparent conductive layer 20, the proportion of tin oxide in the first ITO layer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 1% by mass or more. , more preferably 1.5% by mass or more, particularly preferably 2% by mass or more. The proportion of tin oxide in the first ITO layer is determined from the viewpoint of ease of forming an amorphous transparent conductive layer by sputtering film formation described below, and from the viewpoint of increase in resistance value of the transparent conductive layer 20 due to heating after crystallization. From the viewpoint of suppressing is 4% by mass or less.

The proportion of tin oxide in ITO can be identified, for example, as follows. First, the abundance ratio of indium atoms (In) and tin atoms (Sn) in ITO as a measurement target is determined by X-ray photoelectron spectroscopy. From the respective abundance ratios of In and Sn in ITO, the ratio of the number of Sn atoms to the number of In atoms in ITO is determined. This gives the tin oxide proportion in ITO. Further, the proportion of tin oxide in ITO can also be determined from the proportion of tin oxide (SnO ₂ ) contained in the ITO target used during sputtering film formation.

The transparent conductive layer 20 may include layers other than the first ITO layer (tin oxide proportion less than 10% by mass). Examples of the other layers include an ITO layer (second ITO layer) with a tin oxide content of 10% by mass or more, and a layer formed from a conductive oxide other than ITO. From the viewpoint of achieving both high transparency and good electrical conductivity of the transparent conductive layer 20, the other layer is preferably a second ITO layer.

The tin oxide proportion of the second ITO layer (tin oxide proportion of 10% by mass or more) is preferably 11% by mass or more, more preferably 12% by mass, from the viewpoint of reducing the resistance value of the transparent conductive layer 20 after heating and crystallization. % or more, more preferably 13% by mass or more. The proportion of tin oxide in the second ITO layer is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, from the viewpoint of ensuring the crystallinity of the transparent conductive layer 20 after heating. be.

FIG. 2 exemplarily shows a case where the transparent conductive layer 20 is formed of two layers, a first layer 21 and a second layer 22, as an example of a case where the transparent conductive layer 20 is formed of a plurality of layers including a first ITO layer. show. In FIG. 2, the first layer 21 or the second layer 22 is the first ITO layer. From the viewpoint of suppressing an increase in resistance value due to heating of the transparent conductive layer 20 after heating and crystallization, it is preferable that the second layer 22 is the first ITO layer.

From the viewpoint of reducing the resistance of the transparent conductive layer 20, the thickness of the transparent conductive layer 20 is preferably 10 nm or more, more preferably 20 nm or more, and still more preferably 30 nm or more. Further, from the viewpoint of suppressing cracking due to heating in the transparent conductive layer 20, the thickness of the transparent conductive layer 20 is preferably 300 nm or less, more preferably 150 nm or less, still more preferably 120 nm or less, even more preferably 100 nm or less, and particularly preferably is 80 nm or less.

When the transparent conductive layer 20 includes the first layer 21 and the second layer 22, the ratio of the thickness of the second layer 22 to the total thickness of the first layer 21 and the second layer 22 is From the viewpoint of resistance, it is preferably 1% or more, more preferably 5% or more, and even more preferably 7% or more. Further, the ratio of the thickness of the second layer 22 to the total thickness of the first layer 21 and the second layer 22 is preferably 99% or less from the viewpoint of ensuring high crystallinity in the transparent conductive layer 20 after heating. , more preferably 95% or less, still more preferably 90% or less, even more preferably 60% or less, particularly preferably 50% or less.

The transparent conductive layer 20 contains rare gas atoms (atoms E) having a larger atomic number than argon. Examples of such rare gas atoms include krypton (Kr) and xenon (Xe), and Kr is preferably used. Further, the transparent conductive layer 20 may contain argon (Ar). In this embodiment, the rare gas atoms in the transparent conductive layer 20 are derived from rare gas atoms used as a sputtering gas in the sputtering method described below for forming the transparent conductive layer 20. In this embodiment, the transparent conductive layer 20 is a film (sputtered film) formed by a sputtering method. The transparent conductive layer 20 containing atoms E is formed by crystallizing the transparent conductive layer 20' by heating after forming the amorphous transparent conductive layer 20' containing atoms E, as described later. Ru. Containing atoms E in the transparent conductive layer 20 is suitable for forming an amorphous transparent conductive layer (transparent conductive layer 20' to be described later) in which an increase in resistance value due to heating after crystallization is suppressed. Examples of methods for determining whether the transparent conductive layer 20 contains atoms E include fluorescent X-ray analysis and Rutherford Backscattering Spectrometry (RBS).

The content ratio of atoms E such as Kr in the transparent conductive layer 20 is preferably 1 atomic % or less, more preferably 0.5 atomic % or less, still more preferably 0.3 atomic % or less, especially in the entire thickness direction D. Preferably it is 0.2 atomic % or less. Such a configuration is suitable for achieving good crystal growth when crystallizing the amorphous transparent conductive layer 20' by heating, and is therefore suitable for obtaining a low-resistance transparent conductive layer 20. The content of atoms E in the transparent conductive layer 20 is preferably 0.0001 atomic % or more throughout the thickness direction D. Examples of methods for identifying the content ratio of rare gas atoms in the transparent conductive layer 20 include X-ray fluorescence analysis and Rutherford backscattering spectroscopy (RBS).

When the transparent conductive layer 20 includes a plurality of layers, the transparent conductive layer 20 may include a layer containing atoms E (atomic E-containing layer) and a layer not containing atoms E (atomic E-free layer). . The atomic E-free layer is, for example, a layer formed by sputtering film formation using argon as a sputtering gas. In the transparent conductive layer 20 shown in FIG. 2, the first layer 21 or the second layer 22 contains atoms E. From the viewpoint of ensuring the crystallinity of the transparent conductive layer 20 after heating, it is preferable that the first layer 21 contains atoms E.

When the transparent conductive layer 20 includes an atomic E-containing layer and an atomic E-free layer, the ratio of the thickness of the atomic E-containing layer to the total thickness of the atomic E-containing layer and the atomic E-free layer after heating is From the viewpoint of increasing the crystallinity of the transparent conductive layer 20 and improving the transmittance, it is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40%. That's all. The same ratio is preferably 99 or less, more preferably 90% or less, still more preferably 80% or less, even more preferably 70% or less, particularly preferably It is 60% or less.

The transparent conductive layer 20 has a first resistance value R1 (Ω/□) and has a second resistance value R2 (Ω/□) after heat treatment at 160° C. for 30 minutes. The resistance values R1 and R2 are each expressed by surface resistivity. Surface resistivity can be measured by a four-terminal method based on JIS K7194 (1994). Specifically, the method of measuring the resistance values R1 and R2 is as described later in connection with Examples.

The ratio R2/R1 of the second resistance value R2 to the first resistance value R1 is 0.990 or less, preferably 0.950 or less, more preferably is 0.900 or less, more preferably 0.880 or less. Further, from the viewpoint of suppressing the amount of resistance fluctuation due to subsequent heating of the transparent conductive layer 20, the ratio R2/R1 is 0.650 or more, preferably 0.700 or more, and more preferably 0.800 or more.

The difference R1-R2 between the first resistance value R1 and the second resistance value R2 is preferably 1.5Ω/□ or more, from the viewpoint of suppressing the resistance value from increasing due to subsequent heating in the transparent conductive layer 20. More preferably 3Ω/□ or more, still more preferably 4Ω/□ or more, even more preferably 5Ω/□ or more, particularly preferably 6Ω/□ or more. Further, from the viewpoint of suppressing the amount of resistance fluctuation due to subsequent heating of the transparent conductive layer 20, the difference R1-R2 is preferably 10Ω/□ or less, more preferably 9.5Ω/□ or less, and even more preferably 9Ω/□. It is particularly preferably 8Ω/□ or less.

From the viewpoint of reducing the resistance of the transparent conductive layer 20, the first resistance value R1 is preferably 240 Ω/□ or less, more preferably 220 Ω/□ or less, even more preferably 200 Ω/□ or less, even more preferably 180 Ω/□ or less, It is even more preferably 160 Ω/□ or less, particularly preferably 150 Ω/□ or less. The first resistance value R1 is, for example, 1Ω/□ or more. The first resistance value R1 can be controlled, for example, by adjusting various conditions when sputtering the transparent conductive layer 20 (the same applies to the second resistance value R2). The conditions include, for example, the temperature of the base (transparent resin base material 10 in this embodiment) on which the transparent conductive layer 20 is formed, the amount of oxygen introduced into the film forming chamber, the atmospheric pressure inside the film forming chamber, and the temperature above the target. horizontal magnetic field strength.

From the viewpoint of reducing the resistance of the transparent conductive layer 20, the second resistance value R2 is preferably 240 Ω/□ or less, more preferably 220 Ω/□ or less, even more preferably 200 Ω/□ or less, even more preferably 180 Ω/□ or less, It is even more preferably 160 Ω/□ or less, particularly preferably 150 Ω/□ or less. The second resistance value R2 is, for example, 1Ω/□ or more.

The total light transmittance (JIS K 7375-2008) of the transparent conductive layer 20 is preferably 60% or more, more preferably 80% or more, and still more preferably 85% or more. Such a configuration is suitable for ensuring transparency in the transparent conductive layer 20. Further, the total light transmittance of the transparent conductive layer 20 is, for example, 100% or less.

The transparent conductive film X is manufactured, for example, as follows.

First, as shown in FIG. 3A, a resin film 11 is prepared.

Next, as shown in FIG. 3B, a functional layer 12 is formed on one surface of the resin film 11 in the thickness direction D. By forming the functional layer 12 on the resin film 11, the transparent resin base material 10 is produced.

The above-mentioned functional layer 12 as a hard coat layer can be formed by applying a curable resin composition onto the resin film 11 to form a coating film, and then curing this coating film. When the curable resin composition contains an ultraviolet curable resin, the coating film is cured by ultraviolet irradiation. When the curable resin composition contains a thermosetting resin, the coating film is cured by heating.

The exposed surface of the functional layer 12 formed on the resin film 11 is subjected to a surface modification treatment, if necessary. When performing plasma treatment as surface modification treatment, for example, argon gas is used as the inert gas. Further, the discharge power in the plasma treatment is, for example, 10 W or more and, for example, 5000 W or less.

Next, as shown in FIG. 3C, an amorphous transparent conductive layer 20' is formed on the transparent resin base material 10 (transparent conductive layer forming step). Specifically, a material is formed into a film on the functional layer 12 of the transparent resin base material 10 by a sputtering method to form an amorphous transparent conductive layer 20'. The transparent conductive layer 20' is an amorphous film that has both light transmittance and conductivity (the transparent conductive layer 20' is converted into a crystalline transparent conductive layer 20 by heating in a crystallization process described below). ).

In the sputtering method, it is preferable to use a sputter film forming apparatus that can perform the film forming process in a roll-to-roll manner. When using a roll-to-roll type sputtering film forming apparatus in manufacturing the transparent conductive film A material is deposited on the resin base material 10 to form a transparent conductive layer 20'. In addition, in the sputtering method, a sputter film forming apparatus having one film forming chamber may be used, or a sputter film forming apparatus having a plurality of film forming chambers arranged in order along the travel path of the transparent resin base material 10 may be used. A film forming apparatus may be used (in the case of forming the transparent conductive layer 20' including the first layer 21 and the second layer 22 described above, a sputter film forming apparatus having two or more film forming chambers may be used). do).

Specifically, in the sputtering method, a sputtering gas (inert gas) is introduced under vacuum conditions into a film forming chamber equipped with a sputter film forming apparatus, and a negative voltage is applied to a target placed on a cathode in the film forming chamber. Apply. As a result, a glow discharge is generated to ionize gas atoms, the gas ions collide with the target surface at high speed, the target material is ejected from the target surface, and the ejected target material is deposited on the transparent resin base material 10. . As the material of the target, for example, the sintered body of the conductive oxide described above with respect to the transparent conductive layer 20 is used. Examples of the sputtering gas include rare gases. Examples of rare gases include argon and krypton. The sputtering gas may be a mixed gas of a plurality of rare gases.

The sputtering method is preferably a reactive sputtering method. In the reactive sputtering method, for example, oxygen as a reactive gas is introduced into the film forming chamber in addition to the sputtering gas. In the reactive sputtering method, the ratio of the amount of oxygen introduced to the total amount of sputtering gas and oxygen introduced into the film forming chamber is, for example, 0.01 flow% or more and, for example, 15 flow% or less.

When forming the transparent conductive layer 20 containing rare gas atoms (atoms E) having a larger atomic number than argon (Ar) over the entire area in the thickness direction D (first case), 1 or The gas introduced into the two or more film forming chambers contains atoms E as a sputtering gas and oxygen as a reactive gas. As the atom E, as mentioned above, Kr and Xe can be mentioned, and Kr is preferably used. The sputtering gas may contain an inert gas other than the atom E. Examples of the inert gas other than the atom E include Ar. When the sputtering gas contains an inert gas other than the atom E, the content thereof is preferably 80% by volume or less, more preferably 50% by volume or less.

When forming the transparent conductive layer 20 including the atomic E-containing layer and the atomic E-free layer described above (second case), the gas introduced into the film forming chamber for forming the atomic E-containing layer is sputtered. It contains atoms E as a gas and oxygen as a reactive gas. The sputtering gas may contain an inert gas other than the atom E. The type and content ratio of the inert gas other than the atom E are the same as the type and content ratio described above for the inert gas other than the atom E in the first case. Further, the gas introduced into the film forming chamber for forming the atom E-free layer contains an inert gas other than the atom E as a sputtering gas and oxygen as a reactive gas. Examples of the inert gas other than the atom E include Ar.

The atmospheric pressure inside the film formation chamber during film formation by sputtering (sputter film formation) is, for example, 0.02 Pa or more and, for example, 1 Pa or less.

The temperature of the transparent resin base material 10 during sputter film formation is, for example, 180° C. or lower. The temperature of the transparent resin base material 10 during sputter film formation is preferably set at a temperature from the viewpoint of suppressing outgassing from the transparent resin base material 10 during sputter film formation to appropriately form the amorphous transparent conductive layer 20'. The temperature is 20°C or lower, more preferably 10°C or lower, even more preferably 5°C or lower, even more preferably 0°C or lower, particularly preferably -5°C or lower. The temperature is, for example, -50°C or higher, -20°C or higher, or -10°C or higher.

Examples of power sources for applying voltage to the target include DC power sources, AC power sources, MF power sources, and RF power sources. As the power source, a DC power source and an RF power source may be used together. The absolute value of the discharge voltage during sputter film formation is, for example, 50V or more and, for example, 500V or less.

In this manufacturing method, next, as shown in FIG. 3D, the amorphous transparent conductive layer 20' is converted into a crystalline transparent conductive layer 20 by heating under vacuum (crystallization step). In this step, a vacuum heating device equipped with a contact heating unit is used. Examples of contact heating units include heating rolls and heating blocks. In order to carry out the crystallization step in a roll-to-roll manner, a vacuum heating device equipped with heating rolls is preferred. That is, in this step, it is preferable to heat the transparent conductive layer 20' on the transparent resin base material 10 by bringing it into contact with a heating roll in a vacuum heating device. Contact heating using a heating roll is suitable for efficiently crystallizing the transparent conductive layer 20' under vacuum.

In this step, the heating temperature is preferably 120°C or higher, more preferably 140°C or higher, and even more preferably 160°C or higher, from the viewpoint of ensuring a high crystallization rate. From the viewpoint of suppressing the influence of heating on the transparent resin base material 10, the heating temperature is preferably less than 200°C, more preferably 180°C or less, and still more preferably 170°C or less. From the viewpoint of sufficient crystallization of the transparent conductive layer 20, the heating time is preferably 10 seconds or more, preferably 30 seconds or more, and more preferably 45 seconds or more. From the viewpoint of shortening the takt time in this step, the heating time is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 10 minutes or less, particularly preferably 5 minutes or less.

Preferably, a series of processes from the above-described transparent conductive layer forming step to the crystallization step are carried out in one continuous line while running the work film in a roll-to-roll manner. More preferably, the work film is never exposed to the atmosphere during the process in one continuous line.

Transparent conductive film X is manufactured as described above.

The transparent conductive layer 20 in the transparent conductive film X may be patterned as schematically shown in FIG. The transparent conductive layer 20 can be patterned by etching the transparent conductive layer 20 through a predetermined etching mask. Patterning of the transparent conductive layer 20 may be performed before the above-mentioned crystallization step or after the crystallization step. The patterned transparent conductive layer 20 functions as, for example, a wiring pattern.

As described above, in the transparent conductive film X, the crystalline transparent conductive layer 20 contains rare gas atoms having an atomic number larger than that of argon. The fact that the transparent conductive layer 20 is a crystalline film is suitable for suppressing large fluctuations in the resistance value of the transparent conductive layer 20 due to subsequent heating. The fact that the transparent conductive layer 20 contains rare gas atoms having an atomic number larger than that of argon is suitable for forming an amorphous transparent conductive layer 20' in which an increase in resistance value due to heating after crystallization is suppressed. . The transparent conductive film 0.650 or more, preferably 0.70 or more, more preferably 0.80 or more, and preferably 0.990 or less, more preferably 0.950 or less, still more preferably 0.900 or less. , particularly preferably 0.880 or less. That is, in the transparent conductive film, the second resistance value R2 after the heat treatment (160° C., 30 minutes) is appropriately smaller than the first resistance value R1 before the heat treatment. The transparent conductive film as described above is suitable for suppressing an increase in the resistance value of the transparent conductive layer due to heating during the device manufacturing process.

In the transparent conductive film X, the functional layer 12 may be an adhesion improving layer for realizing high adhesion of the transparent conductive layer 20 to the transparent resin base material 10. The structure in which the functional layer 12 is an adhesion improving layer is suitable for ensuring adhesion between the transparent resin base material 10 and the transparent conductive layer 20.

The functional layer 12 may be an index-matching layer for adjusting the reflectance of the surface (one side in the thickness direction D) of the transparent resin base material 10. The configuration in which the functional layer 12 is a refractive index adjustment layer is suitable for making the pattern shape of the transparent conductive layer 20 difficult to see when the transparent conductive layer 20 on the transparent resin base material 10 is patterned.

The functional layer 12 may be a peelable functional layer that allows the transparent conductive layer 20 to be practically peeled from the transparent resin base material 10. The configuration in which the functional layer 12 is a peelable functional layer is suitable for peeling off the transparent conductive layer 20 from the transparent resin base material 10 and transferring the transparent conductive layer 20 to another member.

The functional layer 12 may be a composite layer in which a plurality of layers are continuous in the thickness direction D. The composite layer preferably includes two or more layers selected from the group consisting of a hard coat layer, an adhesion improving layer, a refractive index adjusting layer, and a release function layer. Such a configuration is suitable for expressing the above-described functions of each selected layer in a composite manner in the functional layer 12. In one preferred form, the functional layer 12 includes an adhesion improving layer, a hard coat layer, and a refractive index adjusting layer on the resin film 11 in this order toward one side in the thickness direction D. In another preferred embodiment, the functional layer 12 includes a release functional layer, a hard coat layer, and a refractive index adjusting layer in this order toward one side in the thickness direction D on the resin film 11.

The transparent conductive film X is fixed to an article and used with the transparent conductive layer 20 patterned as required. The transparent conductive film X is bonded to the article via, for example, an adhesion functional layer.

Examples of articles include elements, members, and devices. That is, examples of the article with a transparent conductive film include an element with a transparent conductive film, a member with a transparent conductive film, and a device with a transparent conductive film.

Examples of the element include a light control element and a photoelectric conversion element. Examples of the light control element include a current drive type light control element and an electric field drive type light control element. Examples of current-driven light control elements include electrochromic (EC) light control elements. Examples of the electric field-driven light control element include a PDLC (polymer dispersed liquid crystal) light control element, a PNLC (polymer network liquid crystal) light control element, and an SPD (suspended particle device) light control element. Examples of photoelectric conversion elements include solar cells and the like. Examples of solar cells include organic thin film solar cells and dye-sensitized solar cells. Examples of the member include an electromagnetic wave shield member, a heat ray control member, a heater member, and an antenna member. Examples of the device include a touch sensor device, a lighting device, and an image display device.

Examples of the above-mentioned fixing functional layer include an adhesive layer and an adhesive layer. The material for the fixing function layer is not particularly limited, as long as it is transparent and exhibits a fixing function. The fixing functional layer is preferably made of resin. Examples of the resin include acrylic resin, silicone resin, polyester resin, polyurethane resin, polyamide resin, polyvinyl ether resin, vinyl acetate/vinyl chloride copolymer, modified polyolefin resin, epoxy resin, fluororesin, natural rubber, and synthetic rubber. It will be done. Acrylic resin is preferred as the resin because it exhibits adhesive properties such as cohesiveness, adhesion, and appropriate wettability, has excellent transparency, and has excellent weather resistance and heat resistance.

The fixing functional layer (resin forming the fixing functional layer) may contain a corrosion inhibitor in order to suppress corrosion of the transparent conductive layer 20. The fixing functional layer (resin forming the fixing functional layer) may contain a migration inhibitor (for example, the material disclosed in JP-A-2015-022397) to suppress migration of the transparent conductive layer 20. Furthermore, an ultraviolet absorber may be added to the fixing functional layer (resin forming the fixing functional layer) in order to suppress deterioration during outdoor use of the article. Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, salicylic acid compounds, oxalic acid anilide compounds, cyanoacrylate compounds, and triazine compounds.

In addition, when the transparent resin base material 10 of the transparent conductive film is exposed. In such a case, a cover layer may be placed on the exposed surface of the transparent conductive layer 20. The cover layer is a layer that covers the transparent conductive layer 20, and can improve the reliability of the transparent conductive layer 20 and suppress functional deterioration of the transparent conductive layer 20 due to damage. Such a cover layer is preferably formed from a dielectric material, more preferably from a composite material of resin and inorganic material. Examples of the resin include the resins described above regarding the fixing functional layer. Examples of inorganic materials include inorganic oxides and fluorides. Examples of inorganic oxides include silicon oxide, titanium oxide, niobium oxide, aluminum oxide, zirconium dioxide, and calcium oxide. Examples of fluorides include magnesium fluoride. Moreover, the above-mentioned corrosion inhibitor, migration inhibitor, and ultraviolet absorber may be blended into the cover layer (mixture of resin and inorganic material).

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the examples. In addition, the specific numerical values such as the blending amount (content), physical property values, and parameters described below are the corresponding blending amounts (content) described in the above-mentioned "Detailed Description". Content), physical property values, parameters, etc. can be replaced by upper limits (numeric values defined as ``less than'' or ``less than'') or lower limits (numeric values defined as ``more than'' or ``more than'').

[Example 1]
An ultraviolet curable resin containing an acrylic resin was applied to one side of a long polyethylene terephthalate (PET) film (thickness 50 μm, manufactured by Toray Industries, Inc.) as a transparent resin film to form a coating film. Next, the coating film was cured by ultraviolet irradiation to form a hard coat layer (thickness: 2 μm). In this way, a transparent resin base material including a resin film and a hard coat (HC) layer as a functional layer was produced.

Next, an amorphous transparent conductive layer was formed on the HC layer in the transparent resin base material by a reactive sputtering method (transparent conductive layer forming step). In this step, a roll-to-roll type sputter film forming apparatus (DC magnetron sputter film forming apparatus) was used. The apparatus includes a first film-forming chamber and a second film-forming chamber in which a film-forming process can be carried out while running a work film in a roll-to-roll manner. In this step, specifically, the first sputter film formation in the first film formation chamber and the second sputter film formation in the second film formation chamber were sequentially performed. In the first sputtering film formation, a first layer (thickness: 11 nm) was formed on a transparent resin base material. In the subsequent second sputtering film formation, a second layer (thickness: 11 nm) was formed on the first layer. The conditions for each sputter film formation in this example are as follows.

In the first sputtering film formation, the inside of the sputtering film forming apparatus (first film forming chamber, second film forming chamber) is evacuated until the ultimate vacuum degree in the first film forming chamber reaches 0.9×10 ^-4 Pa. After that, krypton as a sputtering gas and oxygen as a reactive gas were introduced into the first film forming chamber, and the atmospheric pressure in the first film forming chamber was set to 0.2 Pa. The ratio of the amount of oxygen introduced to the total amount of krypton and oxygen introduced into the first film forming chamber was approximately 1.8% in flow rate. Further, as a target, a first sintered body of indium oxide and tin oxide (tin oxide concentration: 10% by mass) was used. A DC power source was used as a power source for applying voltage to the target. The horizontal magnetic field strength above the target was 90 mT. The film forming temperature (temperature of the transparent resin base material on which the transparent conductive layer is laminated) was -5°C.

In the second sputter film formation, after evacuation of the sputter film formation apparatus, krypton as a sputtering gas and oxygen as a reactive gas are introduced into the second film formation chamber, and the air pressure inside the second film formation chamber is was set to 0.2Pa. The ratio of the amount of oxygen introduced to the total amount of krypton and oxygen introduced into the second film forming chamber was approximately 1.8% in flow rate. Further, as a target, a second sintered body of indium oxide and tin oxide (tin oxide concentration: 3% by mass) was used. A DC power source was used as a power source for applying voltage to the target. The horizontal magnetic field strength above the target was 90 mT. The film forming temperature was -5°C.

Next, the transparent conductive layer on the transparent resin base material was heated in contact with a heating roll in a vacuum heating apparatus to crystallize it (crystallization step). In this step, the heating temperature was 160° C., the heating time was 1 minute, and the transparent conductive layer was heated and crystallized under vacuum.

A series of processes from the transparent conductive layer forming step to the crystallization step described above were carried out on one continuous line while running the work film in a roll-to-roll manner. During this process, the work film is never exposed to the atmosphere.

In the manner described above, the transparent conductive film of Example 1 was produced. The transparent conductive layer (thickness: 22 nm) of the transparent conductive film of Example 1 consisted of a first layer of ITO (tin oxide proportion: 10% by mass, thickness: 11 nm) and a second layer of ITO (tin oxide proportion: 3% by mass). , 11 nm thick) in order from the transparent resin base material side, and is crystalline (the ratio of the thickness of the first layer to the thickness of the transparent conductive layer is 50%, and that of the second layer is 50% of the thickness of the transparent conductive layer. The thickness ratio is 50%).

[Example 2]
A transparent conductive film of Example 2 was produced in the same manner as the transparent conductive film of Example 1 except for the following. A first layer (amorphous) with a thickness of 22 nm is formed in the first sputter film formation of the transparent conductive layer forming step, and a second sintered body (tin oxide concentration of 10% by mass) is used as a target in the second sputter film formation. ) to form a second layer (amorphous) with a thickness of 22 nm.

The transparent conductive layer of the transparent conductive film of Example 2 is made of an ITO film (tin oxide concentration: 10% by mass, thickness: 44 nm) and is crystalline.

[Example 3]
A transparent conductive film of Example 3 was produced in the same manner as the transparent conductive film of Example 1 except for the following. A first layer (amorphous) having a thickness of 22 nm is formed in the first sputtering film formation process of the transparent conductive layer forming step, and in the second sputtering film formation process, argon is used as the sputtering gas, and a second sintered body ( A second layer (amorphous) with a thickness of 22 nm was formed using tin oxide (tin oxide concentration: 10% by mass).

The transparent conductive layer of the transparent conductive film of Example 3 consisted of a first layer containing krypton (tin oxide concentration 10% by mass, thickness 22 nm) and a second layer containing argon (tin oxide concentration 10% by mass, thickness 22 nm). 22 nm) and is crystalline.

[Comparative example 1]
A transparent conductive film of Comparative Example 1 was produced in the same manner as the transparent conductive film of Example 1 except for the following. Argon was used as a sputtering gas in the first sputtering film formation and the second sputtering film formation in the transparent conductive layer forming step. In the crystallization step, the transparent conductive layer on the transparent resin base material was heated in a hot air heating oven. The heating temperature was 160°C, and the heating time was 1 hour. In this step, the transparent conductive layer was heated and crystallized in the atmosphere.

[Comparative example 2]
A transparent conductive film of Comparative Example 2 was produced in the same manner as the transparent conductive film of Example 1 except for the following. Argon was used as a sputtering gas in the first sputtering film formation and the second sputtering film formation in the transparent conductive layer forming process.

[Comparative example 3]
A transparent conductive film of Comparative Example 3 was produced in the same manner as the transparent conductive film of Example 1 except for the following. In the crystallization step, the transparent conductive layer on the transparent resin base material was heated in a hot air heating oven. The heating temperature was 160°C, and the heating time was 1 hour. In this step, the transparent conductive layer was heated and crystallized in the atmosphere.

[Comparative example 4]
A transparent conductive film of Comparative Example 4 was produced in the same manner as the transparent conductive film of Example 1 except for the following. Argon was used as a sputtering gas in the first sputtering film formation and the second sputtering film formation in the transparent conductive layer forming process. In the first sputtering film formation, a first layer (amorphous) with a thickness of 22 nm is formed, and in the second sputtering film formation, a second sintered body (tin oxide concentration of 10% by mass) is used as a target. A 22 nm second layer (amorphous) was formed.

<Thickness of transparent conductive layer>
The thickness of the transparent conductive layer of each transparent conductive film in Examples 1 to 3 and Comparative Examples 1 to 4 was measured by observation with a field emission transmission electron microscope (FE-TEM). Specifically, first, samples for cross-sectional observation of each transparent conductive layer in Examples 1 to 3 and Comparative Examples 1 to 4 were prepared by the FIB microsampling method. In the FIB microsampling method, an FIB device (product name "FB2200", manufactured by Hitachi) was used, and the acceleration voltage was set to 10 kV. Next, the cross section of the transparent conductive layer in the sample for cross-sectional observation was observed using FE-TEM, and the thickness of the transparent conductive layer was measured in the observed image. In this observation, an FE-TEM device (product name "JEM-2800", manufactured by JEOL) was used, and the acceleration voltage was set to 200 kV.

The thickness of the first layer of the transparent conductive layer in Examples 1 and 3 and Comparative Examples 1 to 3 was determined by preparing a sample for cross-sectional observation from an intermediate product before forming the second layer on the first layer. , was measured by FE-TEM observation of the sample. The thickness of the second layer of each transparent conductive layer in Examples 1 and 3 and Comparative Examples 1 to 3 is the thickness of the first layer from the total thickness of each transparent conductive layer in Examples 1 and 3 and Comparative Examples 1 to 3. It was calculated by subtracting the

<crystalline>
The crystallinity of each transparent conductive layer in Examples 1 to 3 and Comparative Examples 1 to 4 was examined by cross-sectional observation using FE-TEM. Specifically, first, samples for cross-sectional observation of each transparent conductive layer in Examples 1 to 3 and Comparative Examples 1 to 4 were prepared by the FIB microsampling method. In the FIB microsampling method, an FIB device (product name "FB2200", manufactured by Hitachi) was used, and the acceleration voltage was set to 10 kV. Next, the cross section of the transparent conductive layer in the sample for cross-sectional observation was photographed using a FE-TEM device (product name "JEM-2800", manufactured by JEOL) at a magnification that allowed the crystal grains to be clearly seen (the accelerating voltage was 200 kV). ). In each of the transparent conductive layers in Examples 1 to 3 and Comparative Examples 1 to 4, it was confirmed that crystal grains grew over the entire area in the plane direction and thickness direction of the same layer (in the plane direction and thickness direction). It was confirmed that the material was crystalline in all directions). On the other hand, in each of the transparent conductive layers in Comparative Examples 2 and 4, it was confirmed that there were regions where crystal grains did not grow in the plane direction and thickness direction of the same layer (in the plane direction and thickness direction). It was not confirmed that it was crystalline in the entire area). From these results, the crystallinity of each transparent conductive layer in Examples 1 to 3 and Comparative Examples 1 and 3 was evaluated as "good," and the crystallinity of each transparent conductive layer in Comparative Examples 2 and 4 was evaluated as "poor." ” The evaluation results are shown in Table 1.

<Transmittance>
For each transparent conductive film of Examples 1 to 3 and Comparative Examples 1 to 4, total light transmittance (JIS K 7375-2008) was measured using a transmittance measuring device (product name "HM-150", manufactured by Murakami Color Research Institute). was measured. The measurement results are shown in Table 1 as transmittance (%).

<Resistance change due to heating>
For each of the transparent conductive films of Examples 1 to 3 and Comparative Examples 1 to 4, changes in resistance values due to post-heating were examined. Specifically, it is as follows.

First, the first resistance value R1 (surface resistivity before heat treatment) of the transparent conductive layer of the transparent conductive film was measured by a four-terminal method according to JIS K 7194 (1994). Next, the transparent conductive film was heat-treated in a hot-air heating oven. In the heat treatment, the heating temperature was 160°C and the heating time was 30 minutes. Next, the second resistance value R2 (surface resistivity after heat treatment) of the transparent conductive layer of the transparent conductive film was measured by a four-terminal method according to JIS K 7194 (1994). Then, the ratio (R2/R1) of the second resistance value R2 to the first resistance value R1 was determined. The values are shown in Table 1. Table 1 also shows the difference R1-R2 between the first resistance value R1 and the second resistance value R2.

<Confirmation of Kr atoms in the transparent conductive layer>
It was confirmed as follows that each transparent conductive layer in Examples 1 to 3 and Comparative Example 3 contained Kr atoms. First, using a scanning X-ray fluorescence analyzer (product name "ZSX Primus IV", manufactured by Rigaku Corporation), X-ray fluorescence analysis measurements were repeated five times under the following measurement conditions, and the average value of each scanning angle was calculated. and created an X-ray spectrum. Then, by confirming that a peak appeared near the scanning angle of 28.2° in the created X-ray spectrum, it was confirmed that Kr atoms were contained in the transparent conductive layer. In this way, it was confirmed that each transparent conductive layer in Examples 1 to 3 and Comparative Example 3 contained Kr atoms, and that each transparent conductive layer in Comparative Examples 1, 2, and 4 did not contain Kr. did.

<Measurement conditions>
Spectrum; Kr-KA
Measurement diameter: 30mm
Atmosphere: Vacuum Target: Rh
Tube voltage: 50kV
Tube current: 60mA
Primary filter: Ni40
Scanning angle (deg): 27.0 to 29.5
Step (deg): 0.020
Speed (deg/min): 0.75
Attenuator: 1/1
Slit: S2
Spectroscopic crystal: LiF (200)
Detector: SC
PHA: 100-300

The transparent conductive film of the present invention can be used, for example, as a supply material for transparent conductor films for transparent electrodes in various devices such as liquid crystal displays, touch panels, and solar cells.

X Transparent conductive film D Thickness direction 10 Transparent resin base material 11 Resin film 12 Functional layer 20 Transparent conductive layer 21 First layer 22 Second layer

Claims (4)

A transparent conductive film comprising a transparent resin base material and a crystalline transparent conductive layer in this order in the thickness direction,
The transparent conductive layer contains rare gas atoms having an atomic number larger than argon,
The transparent conductive layer has a first resistance value R1 (Ω/□) and has a second resistance value R2 (Ω/□) after heat treatment at 160° C. and 30 minutes heating condition,
A transparent conductive film in which the ratio of the second resistance value R2 to the first resistance value R1 is 0.650 or more and 0.990 or less. The transparent conductive film according to claim 1, wherein the transparent conductive layer includes an indium tin composite oxide layer with a tin oxide content of less than 10% by mass. The transparent conductive film according to claim 1 or 2, wherein the transparent conductive layer has a thickness of 150 nm or less. The transparent conductive film according to claim 1 or 2, wherein the first resistance value R1 is 220Ω/□ or less.

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