Transparent Oxide Film

Abstract

To provide a transparent oxide film with a lower absorbency of light and a lower permeation rate of water vapor.SOLUTION: A transparent oxide film 1 includes a transparent polymer film 2 and a transparent oxide membrane 3 sequentially, toward at least one side in a thickness direction. The transparent oxide membrane 3 contains zinc, tin, magnesium and / or aluminum, and oxygen. A percentage of a total amount of the zinc, the tin, the magnesium and the aluminum is over 90 atom% with regard to a total amount of chemical elements other than the oxygen contained in the transparent oxide membrane 3. A percentage of a total amount of the magnesium and the aluminum is over 10 atom% to 50 atom% or less, with regard to the total amount of the zinc, the tin, the magnesium and the aluminum.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transparent oxide film. [Background technology]

[0002] Transparent barrier films having a permeation barrier layer made of a compound of zinc, tin, and oxygen are known (see, for example, Patent Document 1 below). Also known are barrier films having an inorganic film formed of a double oxide of zinc, tin, and silicon (see, for example, Patent Document 2 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2010-524732 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-223784 Summary of the Invention [Problem to be solved by the invention]

[0004] Transparent barrier films are required to have excellent transparency, that is, low light absorption. However, the transparent barrier film made of a compound of zinc, tin, and oxygen described in Patent Document 1 has an energy band gap of the compound of zinc, tin, and oxygen that is close to the energy of the short-wavelength component of visible light, and therefore, light absorption increases in the short-wavelength region of visible light, which may result in low transmittance on the short-wavelength side.

[0005] Barrier films are required to have a lower level of water vapor permeability. However, the barrier film described in Patent Document 2 contains a large amount of silicon, at 20% by weight or more, which may result in a high water vapor permeability.

[0006] The present invention provides a transparent oxide film that has low light absorption and low water vapor transmission rate. [Means for solving the problem]

[0007] The present invention (1) includes a transparent oxide film comprising, in order toward at least one side in a thickness direction, a transparent polymer film and a transparent oxide film, wherein the transparent oxide film contains zinc, tin, magnesium and / or aluminum, and oxygen, wherein the percentage of the total amount of the zinc, tin, magnesium, and aluminum to the total amount of elements other than oxygen contained in the transparent oxide film exceeds 90 atomic %, and the percentage of the total amount of the magnesium and aluminum to the total amount of the zinc, tin, magnesium, and aluminum is more than 10 atomic % and not more than 50 atomic %.

[0008] The present invention (2) is characterized in that the transparent oxide film has a density of 5.0 g / cm 3 The transparent oxide film according to (1) has a density of at least 1000 nm. [Effects of the Invention]

[0009] The transparent oxide film of the present invention has low light absorption and low water vapor transmission rate. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows a cross-sectional view of one embodiment of the transparent oxide film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] [One embodiment of a transparent oxide film] One embodiment of the transparent oxide film of the present invention will be described with reference to FIG.

[0012] This transparent oxide film 1 extends in a planar direction. The planar direction is perpendicular to the thickness direction of the transparent oxide film 1. A transparent polymer film 2 and a transparent oxide film 3 are provided in this order toward one side in the thickness direction. In this embodiment, the transparent oxide film 1 includes only the transparent polymer film 2 and the transparent oxide film 3.

[0013] [Transparent polymer film 2] The transparent polymer film 2 extends in the planar direction. The transparent polymer film 2 forms the other surface of the transparent oxide film 1 in the thickness direction. The transparent polymer film 2 is made of a polymer. Examples of the polymer include acrylic resin, polyester resin, and polyolefin resin. Examples of the acrylic resin include polymethyl methacrylate, polyethyl methacrylate, and polybutyl acrylate. Examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and isophthalate copolymer. Examples of the polyolefin resin include cycloolefin polymer resin, polyethylene resin, and polypropylene resin. From the viewpoint of transparency, polyester resin and polyolefin resin are preferred, and polyethylene terephthalate and cycloolefin polymer resin are more preferred. The thickness of the transparent polymer film 2 is, for example, 10 μm or more, preferably 50 μm or more, and for example, 400 μm or less, preferably 200 μm or less.

[0014] Absorption of light on the short wavelength side is caused by the band gap. Because the band gap is close to the short wavelength component of visible light, there is a risk of absorption in the short wavelength region. On the other hand, a wide band gap shifts the short wavelength absorption edge toward the short wavelength side, thereby reducing visible light absorption, i.e., improving transparency. Therefore, attention is focused on the absorptance of the transparent polymer film 2 for light with a wavelength of 380 nm in the short wavelength region of visible light. The absorptance of the transparent polymer film 2 for light with a wavelength of 380 nm is, for example, 4% or less. The absorptance of the transparent polymer film 2 is, for example, a catalog value. An easy-adhesion layer (not shown) may be formed on the other surface in the thickness direction of the transparent polymer film 2.

[0015] [Transparent oxide film 3] The transparent oxide film 3 extends in the planar direction. The transparent oxide film 3 forms one surface in the thickness direction of the transparent oxide film 1. The transparent oxide film 3 is disposed on one surface in the thickness direction of the transparent polymer film 2. Specifically, the transparent oxide film 3 is in contact with the entire one surface in the thickness direction of the transparent polymer film 2.

[0016] [Elemental composition of transparent oxide film 3] The transparent oxide film 3 contains zinc, tin, magnesium and / or aluminum, and oxygen. For example, the transparent oxide film 3 is made of an oxide composition containing zinc, tin, magnesium and / or aluminum, and oxygen. More specifically, the transparent oxide film 3 is made of a composite oxide of zinc, tin, and magnesium and / or aluminum.

[0017] [Zinc and Tin] Both zinc and tin are contained in the transparent oxide film 3 as essential elements.

[0018] [Magnesium and / or Aluminum] At least one of magnesium and aluminum is contained as an essential element in the transparent oxide film 3. "The transparent oxide film 3 contains magnesium and / or aluminum" includes any of the following: a first embodiment in which the transparent oxide film 3 contains magnesium and aluminum; a second embodiment in which the transparent oxide film 3 contains magnesium but not aluminum; and a third embodiment in which the transparent oxide film 3 contains aluminum but not magnesium. Oxides of magnesium and aluminum are insulators with a large energy band gap. By forming an oxide film from a compound of zinc, tin, and oxygen, whose energy band gap is close to the energy of the short-wavelength component of visible light, and by adding at least one of magnesium and aluminum, the energy band gap is widened, making it possible to reduce light absorption in the short-wavelength region of visible light.

[0019] The ratio of the total amount of magnesium and aluminum to the total amount of zinc, tin, magnesium, and aluminum exceeds 10 atomic %. The ratio of the total amount of magnesium and aluminum is preferably 11 atomic % or more, more preferably 15 atomic % or more, and even more preferably 20 atomic % or more. If the ratio of the total amount of magnesium and aluminum is below the lower limit, the absorptance of light at a wavelength of 380 nm increases. Therefore, the band gap of the transparent oxide film 3 is similar to that of visible light, resulting in a lack of transparency across the entire visible light range. The ratios described above are common to all of the first to third embodiments.

[0020] The ratio of the total amount of magnesium and aluminum to the total amount of zinc, tin, magnesium, and aluminum is 50 atomic % or less. Furthermore, the ratio of the total amount of magnesium and aluminum is preferably 45 atomic % or less, more preferably 40 atomic % or less, even more preferably 35 atomic % or less, and particularly preferably 25 atomic % or less. If the ratio of the total amount of magnesium and aluminum exceeds the upper limit, the water vapor transmission rate increases. The ratios described above are common to all of the first to third embodiments.

[0021] In particular, in the second embodiment in which the transparent oxide film 3 contains magnesium as an essential element, the proportion of magnesium relative to the total amount of zinc, tin, and magnesium is, for example, 10 atomic % or more, or, for example, 20 atomic % or more, and, for example, 40 atomic % or less, preferably 35 atomic % or less, and more preferably 30 atomic % or less. If the proportion of magnesium is equal to or greater than the above-mentioned lower limit, the absorptance of light at a wavelength of 380 nm can be reduced. In other words, the band gap of the transparent oxide film 3 is increased, thereby reducing the absorption of visible light. If the proportion of magnesium is equal to or less than the above-mentioned upper limit, the water vapor permeability can be reduced.

[0022] In particular, in the third embodiment in which the transparent oxide film 3 contains aluminum as an essential element, the ratio of aluminum to the total amount of zinc, tin, and aluminum is, from the viewpoint of reducing the absorptance for light with a wavelength of 380 nm, for example, 20 atomic % or more, preferably 30 atomic % or more, and for example, 50 atomic % or less, preferably 45 atomic % or less. From the viewpoint of reducing the water vapor transmission rate, the above-mentioned ratio of aluminum is, from the viewpoint of reducing the water vapor transmission rate, 10 atomic % or more, preferably 12 atomic % or more, and 40 atomic % or less, preferably 20 atomic % or less.

[0023] [oxygen] Oxygen is an essential element in the transparent oxide film 3. Oxygen forms a complex oxide with zinc, tin, and magnesium and / or aluminum.

[0024] [Other elements] The transparent oxide film 3 may contain other elements in addition to zinc, tin, magnesium, and / or aluminum. The other elements are, for example, impurity elements inevitably mixed in during the manufacturing process. The other elements are not limited. Examples of the other elements include calcium and silicon. The total amount of the other elements, zinc, tin, magnesium, and aluminum, i.e., the ratio of the total amount of zinc, tin, magnesium, and aluminum to the total amount of elements contained in the transparent oxide film 3 other than the gas used during film formation, specifically, the ratio of the total amount of zinc, tin, magnesium, and aluminum to the total amount of elements other than oxygen, exceeds 90 atomic %. The total ratio of zinc, tin, magnesium, and aluminum is preferably 93 atomic % or more, more preferably 96 atomic % or more, and even more preferably 98 atomic % or more. If the other element is calcium and the ratio is below the lower limit, the hygroscopicity increases. If the other element is silicon and the ratio is below the lower limit, the water vapor transmission rate increases.

[0025] The density of the transparent oxide film 3 is, for example, 2.0 g / cm 3 More than 5.0 g / cm 3or more, and for example, 10.0 g / cm 3 When the density of the transparent oxide film 3 is equal to or greater than the lower limit, the film quality of the transparent polymer film 2 becomes dense and the gas barrier property (particularly, the water vapor barrier property) is excellent.

[0026] There are no limitations on the thickness of the transparent oxide film 3. The thickness of the transparent oxide film 3 is, for example, 1 nm or more, or preferably 30 nm or more, and for example, 1000 nm or less, or preferably 300 nm or less.

[0027] The transparent oxide film 1 has a thickness of 11 μm or more, preferably 52 μm or more, and for example, 410 μm or less, preferably 205 μm or less.

[0028] [Physical properties of transparent oxide film 1] The water vapor permeability of the transparent oxide film 1 is, for example, 10×10 -3 (g / m 2 / day) or less, preferably 9 × 10 -3 (g / m 2 / day) or less, more preferably 8×10 -3 (g / m 2 / day) or less, more preferably 6×10 -3 (g / m 2 / day) or less, particularly preferably 5 × 10 -3 (g / m 2 / day) or less. When the water vapor transmission rate of the transparent oxide film 1 is equal to or less than the above upper limit, the transparent oxide film 1 has excellent barrier properties (particularly excellent water vapor barrier properties). There is no restriction on the lower limit of the water vapor transmission rate of the transparent oxide film 1. The method for measuring the water vapor transmission rate will be described later in the Examples.

[0029] From the viewpoint of the band gap of the transparent oxide film 1 and the shift of the absorption edge in the short wavelength region of visible light, the absorptance of the transparent oxide film 1 for light with a wavelength of 380 nm is, for example, 8% or less, preferably 6% or less, and more preferably 5% or less. When the absorptance of the transparent oxide film 1 for light with a wavelength of 380 nm is equal to or less than the above-mentioned upper limit, the transparent oxide film 1 has excellent transparency because the absorption edge on the short wavelength side of visible light is shifted to the shorter wavelength side than the visible light region. There is no lower limit for the absorptance of the transparent oxide film 1 for light with a wavelength of 380 nm. The method for measuring the absorptance will be described in the Examples below.

[0030] [Method of manufacturing transparent oxide film 1] The method for producing the transparent oxide film 1 is not limited. For example, first, a transparent polymer film 2 is prepared. Then, a transparent oxide film 3 is formed on one surface of the transparent polymer film 2 in the thickness direction. The method for forming the transparent oxide film 3 is not limited. For example, a dry process can be used as the method for forming the transparent oxide film 3. Examples of dry processes include sputtering and vacuum deposition. A dry process is preferably used as the method for forming the transparent oxide film 3 in order to form a thin transparent oxide film 3, and sputtering is more preferably used in order to form a dense transparent oxide film 3.

[0031] In sputtering, multiple or single targets containing zinc, tin, magnesium, and / or aluminum are used as cathodes. For example, a first target consisting of a zinc and tin compound, a second target consisting of zinc, and a third target consisting of magnesium and / or aluminum are placed at intervals in a film formation chamber. Some of the targets may be metal oxides. Alternatively, for example, they may be alloy targets consisting of compounds containing zinc, tin, magnesium, and / or aluminum, or metal oxide targets containing oxygen. A transparent polymer film 2 is placed on a separate film formation plate, which serves as an anode. The film formation plate may be rotatable, for example. Each target is positioned facing the film formation plate at an interval. Alternatively, for example, a drum roll may be used as a film formation roll instead of the film formation plate. By placing a drum roll in the film formation chamber, a transparent oxide film 3 can be continuously formed while the transparent polymer film 2 is transported in a roll-to-roll manner.

[0032] Examples of sputtering gases include argon and a mixed gas of oxygen and argon. The ratio of each gas species in the mixed gas is not limited.

[0033] The atomic ratios of zinc, tin, magnesium, and aluminum are adjusted by adjusting the power applied to the first, second, and third targets. Alternatively, sputtering is performed using an alloy target in which the atomic ratios of zinc, tin, magnesium, and / or aluminum have been adjusted in advance, or a metal oxide target that further contains oxygen.

[0034] The use of this transparent oxide film 1 is not particularly limited. Examples include image display devices and solar cells. Examples of image display devices include organic electroluminescence (EL) displays. Examples of solar cells include flexible solar cells. The transparent oxide film 1 is used, for example, as a transparent water vapor barrier film.

[0035] [Effects of one embodiment] In this transparent oxide film 1, the ratio of the total amount of zinc, tin, magnesium, and aluminum to the total amount of elements other than oxygen contained in the transparent oxide film 3 exceeds 90 atomic %, and the percentage of the total amount of magnesium and aluminum to the total amount of zinc, tin, magnesium, and aluminum is more than 10 atomic % and not more than 50 atomic %. Therefore, the transparent oxide film 1 has low light absorption and low water vapor permeability.

[0036] In addition, the transparent oxide film 3 has a density of 5.0 g / cm 3 If the transparent oxide film 3 has a density above this level, it will have excellent gas barrier properties. In particular, the transparent oxide film 3 will have excellent water vapor barrier properties.

[0037] [Variations] In the modified example, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modified example can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and its modified example can be combined as appropriate.

[0038] In the present invention, the transparent oxide film 3 is disposed on at least one side of the transparent polymer film 2. Therefore, as shown by the imaginary line in Fig. 1, the transparent oxide film 3 may be disposed on one surface and the other surface in the thickness direction of the transparent polymer film 2. The transparent oxide film 1 of this modification includes the transparent oxide film 3, the transparent polymer film 2, and the transparent oxide film 3 in this order toward one side in the thickness direction. [Example]

[0039] Specific numerical values ​​of blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of blending ratios (content ratios), physical property values, parameters, etc. described in the above "Description of the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass.

[0040] [Example 1] A polyethylene terephthalate film was prepared as the transparent polymer film 2 .

[0041] Next, a transparent oxide film 3 was formed by sputtering on one surface of the transparent polymer film 2 in the thickness direction.

[0042] Specifically, the first target is ZnSnO x A ZnO (composition ratio Zn / Sn = 50 / 50 atomic %) target was used. ZnO was used as the second target. MgO was used as the third target. The first, second, and third targets were placed in the film formation chamber of a sputtering device. A transparent polymer film 2 was set on the film formation plate. After evacuating the film formation chamber, Ar gas and O2 gas were introduced. Then, 86 W of power was applied to the first target from a DC power supply, 92 W of power was applied to the second target from an RF power supply, and 200 W of power was applied to the third target from an RF power supply. This resulted in the formation of a transparent oxide film 3 with a target thickness of 100 nm on one side of the transparent polymer film 2 in the thickness direction.

[0043] [Example 2] A transparent oxide film 3 was formed in the same manner as in Example 1. However, the power applied to the first target was changed to 37 W, the power applied to the second target was changed to 50 W, and the power applied to the third target was changed to 200 W.

[0044] [Example 3] A transparent oxide film 3 was formed in the same manner as in Example 1. However, the power applied to the first target was changed to 20 W, the power applied to the second target was changed to 35 W, and the power applied to the third target was changed to 200 W.

[0045] [Example 4] A transparent oxide film 3 was formed in the same manner as in Example 1. However, the third target was changed from MgO to Al, the power applied to the first target was changed to 81 W, the power applied to the second target was changed to 74 W, and the power applied to the third target was set to 200 W.

[0046] [Example 5] A transparent oxide film 3 was formed in the same manner as in Example 4. However, the power applied to the first target was changed to 27 W, the power applied to the second target was changed to 34 W, and the power applied to the third target was changed to 200 W.

[0047] [Example 6] A transparent oxide film 3 was formed in the same manner as in Example 1, except that the first target was ZnSnO x The composition ratio of Zn / Sn was changed to 55 / 45 atomic percent (Zn / Sn=55 / 45 atomic percent), the second target was changed to MgZnO (MgO 12 mass%), the third target was changed to Al, the power applied to the DC power supply for the first target was changed to 54 W, the power applied to the RF power supply for the second target was changed to 58 W, and the power applied to the RF power supply for the third target was changed to 150 W.

[0048] [Example 7] The transparent oxide film 3 was formed in the same manner as in Example 1, except that the first cathode was made of ZnSnMgO x The target was changed to a composite oxide target (composition ratio Zn / Sn / Mg=41.3 / 33.8 / 25.0 atomic %), and the power applied to the DC power supply for the first target was changed to 200 W. No power was applied to the second and third targets.

[0049] [Comparative Example 1] A transparent oxide film 3 was formed in the same manner as in Example 1. However, the power applied to the first target was changed to 78 W, the power applied to the second target was changed to 72 W, and no power was applied to the third target.

[0050] Comparative Example 2 A transparent oxide film 3 was formed in the same manner as in Example 1. However, the third target was changed from MgO to SiO2, the power applied to the first target was changed to 40 W, the power applied to the second target was changed to 42 W, and the power applied to the third target was changed to 200 W.

[0051] Comparative Example 3 A transparent oxide film 3 was formed in the same manner as in Example 1. However, the power applied to the first target was changed to 12 W, the power applied to the second target was changed to 28 W, and the power applied to the third target was changed to 200 W.

[0052] Comparative Example 4 A transparent oxide film 3 was formed in the same manner as in Example 6. However, the second target was changed from ZnO to MgZnO (MgO 12 mass %), the power applied to the first target was changed to 60 W, the power applied to the second target was changed to 40 W, and no power was applied to the third target.

[0053] Comparative Example 5 A transparent oxide film 3 was formed in the same manner as in Example 6. However, the target attached to the second target was changed from MgZnO to ZnO, the power applied to the first target was changed to 68 W, the power applied to the second target was changed to 69 W, and the power applied to the third target was changed to 150 W.

[0054] Comparative Example 6 A transparent oxide film 3 was formed in the same manner as in Example 6. However, the power applied to the first target was changed to 18 W, the power applied to the second target was changed to 28 W, and the power applied to the third target was changed to 200 W.

[0055] [evaluation] The transparent oxide film 1 and the transparent oxide film 3 of each example and comparative example were measured for the following items. The results are shown in Table 1.

[0056] (1) Elemental composition of transparent oxide film 3 The elemental composition of the transparent oxide film 3 was analyzed using a fluorescent X-ray analyzer (ZSX PrimusIII+, manufactured by Rigaku). The transparent oxide film 3 was irradiated with X-rays to measure the intrinsic X-ray intensity, and the atomic percentage of each element was calculated from the calculated mass ratio per unit area.

[0057] (2) Water vapor permeability of transparent oxide film 1 The water vapor permeability of the transparent oxide film 1 was measured at a temperature of 40°C, humidity of 90% RH, and an area of ​​50 cm 2 The measurement was carried out under the conditions described above using a water vapor transmission rate measuring device (DELTAPERM, manufactured by Technolocks).

[0058] (3) Light absorptance of transparent oxide film 1 The transmittance of light with a wavelength of 380 nm and the reflectance at an incident angle of 5° of the transparent oxide film 1 were measured using an ultraviolet-visible-near-infrared spectrophotometer (UH4150, manufactured by Hitachi High-Tech Science Corporation). The absorptance of light with a wavelength of 380 nm was calculated by subtracting the transmittance at a wavelength of 380 nm and the reflectance at an angle of 5° from 100%.

[0059] (4) Thickness and density of the transparent oxide film 3 The thickness and density of the transparent oxide film 3 were measured using X-ray reflectivity (XRR). X-rays were irradiated obliquely onto the transparent oxide film 3 in the transparent oxide film 1, and the incidence angle dependence of the total reflected X-ray intensity on one surface in the thickness direction of the transparent oxide film 3 relative to the incident X-ray intensity was measured, thereby obtaining an X-ray intensity profile of the resulting reflected wave. The thickness and density were then determined by simulation fitting of the X-ray intensity profile. Detailed conditions are shown below.

[0060] ·Equipment: Rigaku fully automatic multipurpose X-ray diffraction device SmartLab Analysis software: Rigaku SmartLab Studio II Sample size: 30mm x 30mm ·Incidence X-ray wavelength: 1.5418Å (CuKα) Tube voltage: 40kV ·Tube current: 50mA Output: 2kW Entrance slit: 0.05 mm Receiving slit 1: 0.25 mm Receiving slit 2: 0.375 mm Measurement type: 2θ / θ scan Measurement range (θ): 0.3 to 8.0° Step size (θ): 0.01°

[0061] [Table 1] [Explanation of symbols]

[0062] 1. Transparent oxide film 2. Transparent polymer film 3 Transparent oxide film

Claims

1. A transparent oxide film including a transparent polymer film and a transparent oxide film in this order toward at least one side in a thickness direction, the transparent oxide film includes only the transparent polymer film and the transparent oxide film, the transparent oxide film contains zinc, tin, magnesium and / or aluminum, and oxygen; the percentage of the total amount of the zinc, tin, magnesium, and aluminum relative to the total amount of the elements other than oxygen contained in the transparent oxide film exceeds 90 atomic %; A transparent oxide film, wherein the percentage of the total amount of the magnesium and the aluminum relative to the total amount of the zinc, the tin, the magnesium, and the aluminum is more than 10 atomic % and not more than 50 atomic %.

2. The transparent oxide film has a thickness of 5.0 g / cm ３ The transparent oxide film of claim 1 having a density of at least 1000 nm.

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