Transparent substrate with multilayer film and image display device

Abstract

The present invention pertains to a transparent substrate with a multilayer film, the substrate comprising the multilayer film on at least one out of two main surfaces of the transparent substrate. The multilayer film comprises at least two laminated layers that have different refractive indexes. The multilayer film includes silicon oxide layers. At least one layer from among the silicon oxide layers has a refractive index at a wavelength of 550 nm of 1.460 ≤ n ≤ 1.478.

Description

[Technical Field]

[0001] The present invention relates to a transparent substrate with a multilayer film and an image display device. [Background technology]

[0002] In recent years, from the viewpoint of aesthetics, a technique of installing a cover glass on the front of an image display device such as a liquid crystal display (LCD) has been used. However, one issue is glare caused by the cover glass reflecting external light. To solve this issue, a multilayer film having a laminated structure is often installed on the surface of the cover glass. However, with conventional anti-reflection films, the boundary between the black frame and the image display area of ​​the image display device becomes conspicuous, resulting in poor aesthetics.

[0003] Therefore, it is known that by imparting light absorption ability to an antireflection film, which is a multilayer film formed by laminating at least two or more dielectric layers with different refractive indices, the boundary between the black frame portion and the image display portion of an image display device can be made less noticeable, and reflection from the interface between the cover glass and the antireflection film can also be suppressed. For example, Patent Document 1 discloses a transparent substrate with an antireflection film that has light absorption ability and is insulating. Patent Document 2 discloses a transparent conductive laminate in which a silicon oxide layer and a copper layer are laminated in this order. Patent Document 3 discloses an antireflection film in which a coating made of a high refractive index material and a coating made of a low refractive index material are disposed on the surface of a glass plate, with the coating made of the low refractive index material being disposed on the outermost surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-115105 [Patent Document 2] Japanese Patent Publication No. 2016-068470 [Patent Document 3] Japanese Patent Application Publication No. 2008-201633 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, there are known techniques for imparting light absorption to a multilayer film to provide aesthetic appearance and suppressing reflection from the interface between the cover glass and the multilayer film. However, in conventional multilayer film-coated transparent substrates, the transmittance of the multilayer film can change in high-temperature or high-humidity environments. Therefore, an object of the present invention is to provide a multilayer film-coated transparent substrate in which changes in the transmittance of the multilayer film under high-temperature or high-humidity environments are suppressed, and an image display device including the multilayer film-coated transparent substrate. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by providing a multilayer film with a specific structure, and have completed the present invention. That is, the gist of the present invention is as follows.

[0007] 1. A multilayer film is provided in which at least two layers having different refractive indices are laminated on at least one of the main surfaces of a transparent substrate having two main surfaces, the multilayer film includes a silicon oxide layer; The multilayered transparent substrate has a refractive index of at least one of the silicon oxide layers at a wavelength of 550 nm of 1.460≦n<1.478. 2. The multilayer film further comprises a metal oxide layer; the metal oxide layer is mainly composed of a mixed oxide of at least one oxide selected from Group A consisting of Mo and W and at least one oxide selected from Group B consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In; 2. The transparent substrate with a multilayer film according to 1, wherein in the metal oxide layer, the content of the elements of group B contained in the mixed oxide relative to the total of the elements of group A contained in the mixed oxide and the elements of group B contained in the mixed oxide is less than 80 mass%. 3. A multilayer film is provided in which at least two layers having different refractive indices are laminated on at least one of the main surfaces of a transparent substrate having two main surfaces, a first metal oxide layer that is mainly composed of a mixed oxide of Mo and Nb and has an extinction coefficient k of greater than 0.004 at a wavelength of 550 nm; When the second metal oxide layer is a layer mainly composed of a mixed oxide of Mo and Nb and having an extinction coefficient k of 0.004 or less at a wavelength of 550 nm, the multilayer film includes the first metal oxide layer; At least one of the first metal oxide layers is sandwiched between two of the second metal oxide layers, A transparent substrate with a multilayer film, wherein the second metal oxide layers sandwiching the first metal oxide layer each have a film thickness of 8 nm or more. 4. The multilayer film further comprises a silicon oxide layer; 4. The transparent substrate with a multilayer film according to item 3, wherein the content of elements in group B, consisting of Mo and W, and elements in group B, consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In, contained in the first metal oxide layer, is each less than 80 mass% of the total of the elements in group A, consisting of Mo and W, and the elements in group B, consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In. 5. The transparent substrate with a multilayer film according to any one of items 1 to 4 above, further comprising an antifouling film on the multilayer film. 6. The transparent substrate with a multilayer film according to any one of items 1 to 5 above, wherein the transparent substrate is a glass substrate or a resin substrate. 7. The transparent substrate with a multilayer film according to any one of items 1 to 5 above, wherein the transparent substrate is a laminate composed of glass and a resin substrate. 8. The transparent substrate with a multilayer film according to 6 or 7 above, wherein the glass is chemically strengthened. 9. The transparent substrate with a multilayer film according to any one of items 1 to 8, wherein the transparent substrate has an anti-glare treatment applied to a main surface on the side having the multilayer film. 10. An image display device comprising the transparent substrate with a multilayer film according to any one of items 1 to 9 above. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a transparent substrate with a multilayer film in which the multilayer film has a predetermined structure, and in which changes in the transmittance of the multilayer film are suppressed in high-temperature environments or high-temperature, high-humidity environments, and an image display device including the transparent substrate with a multilayer film. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically showing one example of the configuration of a transparent substrate with a multilayer film according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing one example of the configuration of a transparent substrate with a multilayer film according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] (Transparent substrate with multilayer film) The transparent substrate with a multilayer film according to this embodiment has a transparent substrate having two main surfaces, and is provided with a multilayer film in which at least two layers having different refractive indices are laminated on at least one of the main surfaces of the transparent substrate.

[0012] The transparent substrate with a multilayer film according to this embodiment preferably has a luminous transmittance of 20 to 89%. If the luminous transmittance is within the above range, the substrate has an appropriate light absorption ability, and when used as a cover glass for an image display device, reflection from the interface between the cover glass and the multilayer film can be suppressed. This improves the bright contrast of the image display device. The luminous transmittance can be measured by the method specified in JIS Z 8709 (1999). The luminous transmittance of the transparent substrate with a multilayer film according to this embodiment is more preferably 50 to 89%, and even more preferably 65 to 85%.

[0013] The transparent substrate with a multilayer film according to this embodiment has the configuration described below, which suppresses changes in transmittance in a high-temperature environment. Specifically, for example, the absolute value of the change in transmittance ΔTv before and after 500 hours in an environment at a temperature of 95°C is preferably 2.0% or less, and more preferably 1.0% or less. ΔTv is a value determined using a spectrophotometer by the method described in the Examples section below.

[0014] The transparent substrate with a multilayer film according to this embodiment has the structure described below, which suppresses changes in transmittance in a high-temperature, high-humidity environment. Specifically, for example, the absolute value of the change in transmittance ΔTv before and after 500 hours in an environment of a temperature of 85°C and a humidity of 85% RH is preferably 2.0% or less, and more preferably 1.0% or less. ΔTv is a value determined using a spectrophotometer by the method described in the Examples section below.

[0015] The transparent substrate with a multilayer film according to this embodiment has a sheet resistance of the multilayer film of 10 4 It is preferable that the sheet resistance of the multilayer film is Ω / □ or more. If the sheet resistance of the multilayer film is within the above range, the multilayer film is insulating, and therefore when used as a cover glass of an image display device, even if a touch panel function is provided, the change in capacitance due to finger contact required for a capacitive touch sensor is maintained, allowing the touch panel to function. The sheet resistance can be measured by the method specified in ASTM D257 or JIS K 6271-6 (2008). The sheet resistance of the multilayer film of the transparent substrate with a multilayer film according to this embodiment is 10 6 Ω / □ or more is more preferable, and 10 8 Ω / □ or more is more preferable, and 10 11 Even more preferably, it is Ω / □ or more.

[0016] In the transparent substrate with a multilayer film according to this embodiment, the luminous reflectance of the multilayer film is preferably 1% or less. If the luminous reflectance is within the above range, when the substrate is used as a cover glass for an image display device, the effect of preventing external light from being reflected on the screen can be improved. The luminous reflectance can be measured by the method specified in JIS Z 8701 (1999). The luminous reflectance is more preferably 0.8% or less, and even more preferably 0.6% or less. There is no particular restriction on the lower limit of the luminous reflectance, but it is preferably, for example, 0.05% or more, or 0.1% or more.

[0017] The transparent substrate with a multilayer film according to this embodiment has a transmitted color of b under a D65 light source. * It is preferable that the value is 5 or less. *If the value is within the above range, the transmitted light is not yellowish, and therefore the glass is suitable for use as a cover glass for an image display device. * The value can be measured using the method specified in JIS Z 8729 (2004). * The value is more preferably 3 or less, and even more preferably 2 or less. * The value is preferably −6 or more, more preferably −4 or more. If the value is in the above range, the transmitted light tends to become colorless, and the transmitted light is not obstructed, which is preferable.

[0018] (Multilayer film) The transparent substrate with a multilayer film according to this embodiment has a transparent substrate having two main surfaces, and is provided with a multilayer film formed by laminating at least two layers having different refractive indices on at least one of the main surfaces of the transparent substrate. The multilayer film has the following first or second aspect.

[0019] (First aspect) The multilayer film in the multilayer film-coated transparent substrate according to the first aspect of this embodiment preferably has the following configuration. In a first embodiment, the multilayer film includes silicon oxide layers, and at least one of the silicon oxide layers has a refractive index n at a wavelength of 550 nm that satisfies 1.460≦n<1.478.

[0020] FIG. 1 is a cross-sectional view schematically illustrating an example of the configuration of a multilayer-coated transparent substrate according to the first embodiment. In the multilayer-coated transparent substrate 20 of FIG. 1, a multilayer film 30 is formed on a transparent substrate 10. The multilayer film 30 shown in FIG. 1 has a laminated structure in which two dielectric layers 32 and 34 are stacked as layers with different refractive indices. By stacking the dielectric layers 32 and 34 with different refractive indices, light reflection can be suppressed. In the example of FIG. 1, the dielectric layer 32 is a high-refractive index layer, and the dielectric layer 34 is a low-refractive index layer. Here, "different refractive indices" preferably refer to a difference in refractive index n of 0.2 or more at a wavelength of 550 nm. Furthermore, the high-refractive index layer is, for example, a layer with a refractive index n of 1.8 or more at a wavelength of 550 nm, and the low-refractive index layer is, for example, a layer with a refractive index n of 1.6 or less at a wavelength of 550 nm.

[0021] The multilayer film is mainly composed of SiO x and at least one of the silicon oxide layers has a refractive index n at a wavelength of 550 nm that satisfies 1.460≦n<1.478. For example, in the configuration of Figure 1, the dielectric layer 34 is a silicon oxide layer, and the refractive index n of the silicon oxide layer at a wavelength of 550 nm satisfies 1.460≦n<1.478. In this specification, the phrase "mainly composed of a specific component" means that the specific component is contained in an amount of 70 mass% or more.

[0022] The change in transmittance under high temperature and high temperature / humidity environments is presumed to be due to a change in the transmittance of the multilayer film caused by, for example, an oxidation-reduction reaction occurring in the multilayer film under such environments. Specifically, the following reasons are considered to be the cause. A preferred configuration of the multilayer film in this embodiment includes, for example, a configuration in which a silicon oxide layer and a metal oxide layer are laminated in this order. In such a configuration, under high temperature and high temperature / humidity environments, a redox reaction between the silicon oxide layer and the metal oxide layer may increase the oxidation degree of the silicon oxide layer and decrease the oxidation degree of the metal oxide layer. When the oxidation degree of the metal oxide layer decreases, the absorption coefficient of the metal oxide layer increases, and the transmittance of the multilayer film decreases. In particular, under high temperature / high humidity environments, the presence of moisture is thought to make such redox reactions more likely to proceed. On the other hand, in the above configuration, if the metal oxide layer is prone to react with external oxygen in a high-temperature environment or a high-temperature, high-humidity environment, such a reaction may increase the degree of oxidation of the metal oxide layer, thereby increasing the transmittance of the multilayer film.

[0023] where SiO x It is known that the degree of oxidation correlates with the refractive index, and the higher the degree of oxidation, the smaller the value of the refractive index n at a wavelength of 550 nm. x They found that by adjusting the oxidation degree of and including a silicon oxide layer with a specific range of n value in the multilayer film, it is possible to suppress changes in the transmittance of the multilayer film under high temperature and high temperature / high humidity environments.

[0024] That is, since the n of the silicon oxide layer is less than the above value and the degree of oxidation is relatively high, the silicon oxide layer can be oxidized to SiO 2 under high temperature and high temperature / high humidity environments. x It is considered that the SiO 2 is less likely to be oxidized, and the decrease in the transmittance of the multilayer film can be suppressed. n is less than 1.478, and preferably 1.464 or less. x When the degree of oxidation is greater than a certain level or when the silicon oxide layer is completely oxidized, the silicon oxide layer becomes relatively permeable to oxygen gas and water vapor. Therefore, it is thought that by making n 1.460 or greater, the permeation of oxygen gas and water vapor can be suppressed, and an increase in the transmittance of the multilayer film can be suppressed.

[0025] The thickness of the silicon oxide layer is not particularly limited, but is preferably 20 nm or more, more preferably 60 nm or more, from the viewpoint of low reflectivity, and the total thickness of the silicon oxide layer is preferably 1000 nm or less, more preferably 800 nm or less, from the viewpoint of productivity.

[0026] As described above, the multilayer film preferably further includes a metal oxide layer, because it is easier to obtain a film that has the desired light absorption ability and is insulating. The metal oxide layer is more preferably a metal oxide layer primarily composed of a mixed oxide of at least one oxide selected from Group A consisting of Mo and W and at least one oxide selected from Group B consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In. For example, in the multilayer film 30 shown in FIG. 1, the dielectric layer 32 is preferably a metal oxide layer, more preferably a metal oxide layer primarily composed of the mixed oxide.

[0027] Furthermore, the metal oxide layer is preferably amorphous. If the metal oxide layer is amorphous, it can be produced at a relatively low temperature, and therefore, when the transparent substrate is a resin substrate or the like, the transparent substrate can be prevented from being damaged by heat.

[0028] When the metal oxide layer is primarily composed of the above-mentioned mixed oxide, among the elements constituting the mixed oxide, Mo is preferred as the group A element and Nb as the group B element. That is, it is more preferable that the above-mentioned metal oxide layer is primarily composed of a mixed oxide of Mo and Nb. Conventionally, oxygen-deficient silicon oxide layers tend to be yellowish in visible light. In contrast, by including a metal oxide layer containing Mo and Nb in the multilayer film, yellowing can be suppressed even when the multilayer film includes an oxygen-deficient silicon oxide layer.

[0029] In addition, when the metal oxide layer is mainly composed of the above-mentioned mixed oxides, the b * From the viewpoint of suppressing the value to 5 or less, the content of the group B elements contained in the mixed oxide relative to the total of the group A elements contained in the mixed oxide and the group B elements contained in the mixed oxide (hereinafter referred to as the group B content) is preferably less than 80 mass%. The group B content is more preferably 70 mass% or less, and even more preferably 60 mass% or less. Furthermore, there is no particular restriction on the lower limit of the group B content, but for example, 10 mass% or more is preferred.

[0030] The refractive index of the dielectric layer 32 at a wavelength of 550 nm is preferably 1.8 to 2.3, from the viewpoint of keeping the difference in refractive index with the dielectric layer 34 within an appropriate range and obtaining desirable low reflection characteristics.

[0031] The extinction coefficient k of the dielectric layer 32 at a wavelength of 550 nm is preferably greater than 0.004, more preferably 0.01 or greater, and preferably 3 or less, more preferably 1 or less, and even more preferably 0.38 or less. When the extinction coefficient k is greater than 0.004, the desired light absorptance can be achieved with an appropriate number of layers. Furthermore, when the extinction coefficient k is 3 or less, it is relatively easy to achieve both a desired reflective color and transmittance. There are no particular limitations on the method for adjusting the extinction coefficient k of the dielectric layer 32. For example, when the dielectric layer 32 is a metal oxide layer, the extinction coefficient k varies depending on the elemental species contained and their degree of oxidation. Typically, when the degree of oxidation of the metal oxide is relatively high or completely oxidized, the extinction coefficient k tends to be small, whereas when the degree of oxidation of the metal oxide is relatively low, the extinction coefficient k tends to be large.

[0032] In the first embodiment, the multilayer film may have a laminated structure in which three or more layers having different refractive indices are stacked. In this case, it is not necessary for all layers to have different refractive indices. For example, a three-layer laminated structure can be a three-layer laminated structure of a low-refractive index layer, a high-refractive index layer, and a low-refractive index layer, or a three-layer laminated structure of a high-refractive index layer, a low-refractive index layer, and a high-refractive index layer. In the former case, the two low-refractive index layers may have the same refractive index, and in the latter case, the two high-refractive index layers may have the same refractive index. A four-layer laminated structure can be a four-layer laminated structure of a low-refractive index layer, a high-refractive index layer, a low-refractive index layer, and a high-refractive index layer, a high-refractive index layer, and a low-refractive index layer. In this case, at least one of the two low-refractive index layers and two high-refractive index layers may have the same refractive index. The number of layers constituting the multilayer film and the thickness of each layer can be appropriately changed depending on the desired optical properties, etc.

[0033] In the first embodiment, when the multilayer film includes multiple silicon oxide layers, it is sufficient that the refractive index n at a wavelength of 550 nm of at least one layer is 1.460≦n<1.478. As described above, the multilayer film preferably includes a silicon oxide layer and further includes a metal oxide layer, but the multilayer film may also include other layers in addition to these layers.

[0034] However, it is preferable that the outermost layer of the multilayer film is a silicon oxide layer. This is because, in order to obtain low reflectivity, if the outermost layer is a silicon oxide layer, it is relatively easy to fabricate the multilayer film. Furthermore, when an antifouling film, which will be described later, is formed, it is preferable to form it on a silicon oxide layer from the viewpoint of bonding properties that affect the durability of the antifouling film.

[0035] When the outermost layer of the multilayer film is a silicon oxide layer, it is also preferable that the n of the outermost silicon oxide layer be 1.460≦n<1.478. On the other hand, it is also preferable to provide a silicon oxide layer with a relatively large n on the outermost surface, and in this case, it is also preferable that n be 1.478≦n. This is because, since oxygen gas and water vapor tend to permeate into the multilayer film from the surface side of the multilayer film, by making the n of the outermost silicon oxide layer relatively large, i.e., by making the degree of oxidation relatively small and making it more difficult for oxygen gas and water vapor to permeate into the multilayer film, it is easier to suppress changes in transmittance caused by the permeation of oxygen gas and water vapor into the multilayer film. In this case, the upper limit of n is preferably n<1.6, for example, from the viewpoint of sufficiently suppressing light reflection, and n is more preferably 1.481 or less, and even more preferably 1.480 or less. As a specific configuration example, when the multilayer film includes multiple silicon oxide layers, n of at least one of the silicon oxide layers other than the outermost layer is set to 1.460≦n<1.478, and n of the outermost silicon oxide layer is set to a relatively large value of 1.478≦n<1.6, more preferably 1.478≦n≦1.481, and even more preferably 1.478≦n≦1.480. Alternatively, the outermost silicon oxide layer may be constructed by laminating two types of silicon oxide layers with different n, with the silicon oxide layer at the interface with the lower layer having n of 1.460≦n<1.478, and the silicon oxide layer at the surface side having a relatively large n of 1.478≦n<1.6, more preferably 1.478≦n≦1.481, and even more preferably 1.478≦n≦1.480.

[0036] (Second aspect) The multilayer film in the multilayer film-coated transparent substrate according to the second aspect of this embodiment preferably has the following configuration. When the first metal oxide layer is a layer composed mainly of a mixed oxide of Mo and Nb and having an extinction coefficient k of greater than 0.004 at a wavelength of 550 nm, and the second metal oxide layer is a layer composed mainly of a mixed oxide of Mo and Nb and having an extinction coefficient k of 0.004 or less at a wavelength of 550 nm, the multilayer film in the second embodiment includes first metal oxide layers, at least one of which is sandwiched between two second metal oxide layers, and the thicknesses of the second metal oxide layers sandwiching the first metal oxide layer are each 8 nm or more.

[0037] FIG. 2 is a cross-sectional view schematically illustrating an example of a configuration of a multilayer-coated transparent substrate according to the second embodiment. In the multilayer-coated transparent substrate 20 of FIG. 2, a multilayer film 30 is formed on a transparent substrate 10. The multilayer film 30 shown in FIG. 1 has a laminated structure in which two dielectric layers 32 and 34, each with a different refractive index, are stacked. By stacking the dielectric layers 32 and 34, each with a different refractive index, light reflection can be suppressed. In the example shown in FIG. 2, the dielectric layer 32 is a high-refractive index layer, and the dielectric layer 34 is a low-refractive index layer. In the second embodiment, the dielectric layer 32 is primarily composed of a mixed oxide of Mo and Nb, and is a layer having an extinction coefficient k of greater than 0.004 at a wavelength of 550 nm, i.e., a first metal oxide layer. The first metal oxide layer, the dielectric layer 32, is sandwiched between second metal oxide layers, the dielectric layers 33. The second metal oxide layers (dielectric layers 33) sandwiching the first metal oxide layer each have a thickness of 8 nm or more.

[0038] The first metal oxide layer is primarily composed of a mixed oxide of Mo and Nb, and has an extinction coefficient k of greater than 0.004 at a wavelength of 550 nm. The extinction coefficient k of the first metal oxide layer at a wavelength of 550 nm is preferably 0.01 or greater, more preferably 0.04 or greater. The extinction coefficient k of the first metal oxide layer at a wavelength of 550 nm is preferably 3 or less, more preferably 1 or less, and even more preferably 0.38 or less. An extinction coefficient k of greater than 0.004 allows the desired light absorption rate to be achieved with an appropriate number of layers. Furthermore, an extinction coefficient k of 3 or less makes it relatively easy to achieve both a desired reflection color and transmittance.

[0039] The second metal oxide layer is mainly composed of a mixed oxide of Mo and Nb, and has an extinction coefficient k of 0.004 or less at a wavelength of 550 nm. In the second metal oxide layer, the extinction coefficient k of 0.004 or less at a wavelength of 550 nm is preferred. There is no particular lower limit to the extinction coefficient k at a wavelength of 550 nm, but it is preferably 0.000 or more, and more preferably 0.0001 or more.

[0040] In the first metal oxide layer and the second metal oxide layer, the extinction coefficient k varies depending on the type of element contained and its oxidation degree. The method for adjusting the extinction coefficient k is not particularly limited. For example, when the first metal oxide layer is a mixed oxide of mainly Mo and Nb, MoNbO y When it consists of MoNbO y By making the oxidation degree of Mo relatively small, the extinction coefficient k can be easily increased to more than 0.004, which is preferable. In addition, when the second metal oxide layer is mainly a mixed oxide of Mo and Nb, MoNbO y When it consists of MoNbO y It is preferable to make the degree of oxidation relatively large or to completely oxidize the material, since this makes it easier to make the extinction coefficient k equal to or less than 0.004.

[0041] In the second aspect, at least one layer of the first metal oxide in the multilayer film is sandwiched between two second metal oxide layers, and the thickness of each of the second metal oxide layers sandwiching the first metal oxide layer is 8 nm or more, thereby suppressing changes in transmittance of the multilayer film in high-temperature environments and high-temperature, high-humidity environments. Although the reason for this is unclear, it is presumed that by including a configuration in which the first metal oxide layer is sandwiched between second metal oxide layers with a relatively high degree of oxidation, for example, the reaction is suppressed in the aforementioned redox reaction in the multilayer film, and therefore changes in transmittance are also suppressed, for example, because the reduction reaction species are different from those in conventional multilayer films.

[0042] The content of the elements of group B (group B content) relative to the total of the elements of group A consisting of Mo and W and the elements of group B consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In contained in the first metal oxide layer is* From the viewpoint of suppressing the value to 5 or less, each of the group B contents is preferably less than 80 mass%. The group B content is more preferably 70 mass% or less, and even more preferably 60 mass% or less. There is no particular lower limit to the group B content, but it is preferably, for example, 10 mass% or more. The group B content in the second metal oxide layer is preferably in the same range.

[0043] The first metal oxide layer is preferably amorphous. If it is amorphous, it can be produced at a relatively low temperature, and when the transparent substrate is a resin substrate, the transparent substrate can be prevented from being damaged by heat. For the same reason, it is also preferable that the second metal oxide layer is amorphous.

[0044] The refractive index of the dielectric layer 32 at a wavelength of 550 nm is preferably 1.8 to 2.3, from the viewpoint of keeping the difference in refractive index with the dielectric layer 34 within an appropriate range and obtaining desirable low reflection characteristics.

[0045] The thickness of the first metal oxide layer is not particularly limited, but is preferably 10 nm or more, more preferably 40 nm or more, from the viewpoint of low reflectivity, and the total thickness of the multilayer film including the thickness of the first metal oxide layer is preferably 1000 nm or less, more preferably 800 nm or less, from the viewpoint of productivity.

[0046] The thickness of the second metal oxide layer is not particularly limited, but the thickness of the second metal oxide layers sandwiching the first metal oxide is 8 nm or more, preferably 10 nm or more, and more preferably 50 nm or more. The upper limit of the thickness of the second metal oxide layer is not particularly limited, but is preferably 100 nm or less, for example.

[0047] The multilayer film is mainly made of SiO from the viewpoint of low reflection characteristics. x It is preferable that the dielectric layer further comprises a silicon oxide layer composed of For example, the dielectric layer 34 in Figure 2 is preferably a silicon oxide layer.

[0048] The refractive index n of the dielectric layer 34 at a wavelength of 550 nm is preferably 1.3 to 1.6 from the viewpoint of low reflection characteristics.

[0049] In the second embodiment, the multilayer film may have a laminated structure in which three or more layers having different refractive indices are stacked. In this case, it is not necessary for all layers to have different refractive indices. For example, a three-layer laminated structure can be a three-layer laminated structure of a low-refractive index layer, a high-refractive index layer, and a low-refractive index layer, or a three-layer laminated structure of a high-refractive index layer, a low-refractive index layer, and a high-refractive index layer. In the former case, the two low-refractive index layers may have the same refractive index, and in the latter case, the two high-refractive index layers may have the same refractive index. A four-layer laminated structure can be a four-layer laminated structure of a low-refractive index layer, a high-refractive index layer, a low-refractive index layer, and a high-refractive index layer, a high-refractive index layer, and a low-refractive index layer. In this case, at least one of the two low-refractive index layers and two high-refractive index layers may have the same refractive index. The number of layers constituting the multilayer film and the thickness of each layer can be appropriately changed depending on the desired optical properties, etc.

[0050] In the second embodiment, the multilayer film preferably includes a first metal oxide layer and further includes a silicon oxide layer as described above, but the multilayer film may also include other layers in addition to these layers and the second metal oxide layer. Also, in the second embodiment, the multilayer film may include silicon oxide layers, and the refractive index n of at least one of the silicon oxide layers at a wavelength of 550 nm may be 1.460≦n<1.478. That is, the multilayer film may have a configuration that simultaneously satisfies the second embodiment and the first embodiment.

[0051] However, it is preferable that the outermost layer of the multilayer film is a silicon oxide layer, because a silicon oxide layer can be relatively easily formed as the outermost layer to obtain low reflectivity. Furthermore, when an antifouling film, which will be described later, is formed, it is preferable to form it on a silicon oxide layer from the viewpoint of bonding properties related to the durability of the antifouling film.

[0052] A half-tone mask used in the semiconductor manufacturing field is known as an example of a light-transmitting film that has both light absorption and insulating properties. For half-tone masks, Mo-SiO xAn oxygen-deficient film such as a film is used. As an optically insulating and light-transmitting film having light absorption ability, there is a narrow band gap film used in the field of semiconductor manufacturing. However, these films have a high ability to absorb light at short wavelengths in the visible light spectrum, which causes the transmitted light to have a yellowish tint, making them unsuitable for use as cover glasses for image display devices.

[0053] The composition and optical constants of each layer constituting the multilayer film in the first and second embodiments can be calculated from the results of identification using XPS (X-ray photoelectron spectroscopy), SIMS (secondary ion mass spectroscopy), etc., or from the measurement results of optical properties, once the multilayer film has been formed. When the film formation conditions for each layer can be specified, the optical constants of each layer can also be calculated by forming a single film, i.e., a film consisting of only one layer, on a transparent substrate under the same conditions as the film formation conditions for each layer, and performing spectroscopic measurement on the single film.

[0054] The transparent substrate with a multilayer film according to this embodiment will be further described below. The following configuration is common to the first and second embodiments.

[0055] (transparent base) The transparent substrate is not particularly limited as long as it is a transparent substrate with excellent light transmission, but a material with a refractive index of 1.4 or more and 1.7 or less is preferred, because this allows sufficient suppression of reflection at the bonding surface when optically bonding displays, touch panels, etc.

[0056] The transparent substrate is preferably a glass substrate or a resin substrate, and may be a laminate composed of a glass substrate and a resin substrate.

[0057] Glass having various compositions can be used as the glass substrate. For example, the glass used in this embodiment preferably contains sodium and has a composition that allows strengthening by molding and chemical strengthening treatment. Specific examples include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

[0058] There are no particular limitations on the thickness of the glass substrate, but in order to effectively carry out chemical strengthening treatment when such treatment is to be carried out, the thickness is usually preferably 5 mm or less, and more preferably 3 mm or less.

[0059] The glass substrate or the glass in the laminate composed of glass and resin substrates is preferably chemically strengthened glass that has been chemically strengthened to increase the strength of the cover glass. When the glass substrate is subjected to an antiglare treatment, the chemical strengthening is preferably performed after the antiglare treatment and before the formation of the multilayer film.

[0060] The glass substrate is preferably subjected to an anti-glare treatment on the main surface on which the multilayer film is formed. The anti-glare treatment method is not particularly limited, and a method of performing a surface treatment on the glass main surface to form the desired unevenness can be used. Specifically, a method of performing a chemical treatment on the main surface of the glass substrate, such as a frost treatment, can be used. The frost treatment can be performed, for example, by immersing the glass substrate, which is the object to be treated, in a mixed solution of hydrogen fluoride and ammonium fluoride, and chemically surface-treating the immersed surface. In addition to such chemical treatment methods, physical treatment methods can also be used, such as a sandblasting method in which crystalline silicon dioxide powder, silicon carbide powder, or the like is sprayed onto the glass substrate surface with pressurized air, or a brush to which crystalline silicon dioxide powder, silicon carbide powder, or the like is attached and then polished with a brush moistened with water.

[0061] The resin substrate is preferably a resin film. A thermoplastic resin or a thermosetting resin can be used as the resin film. Examples of the thermoplastic resin or the thermosetting resin include polyvinyl chloride resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl acetate resin, polyester resin, polyurethane resin, cellulose-based resin, acrylic resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, fluorine-based resin, thermoplastic elastomer, polyamide resin, polyimide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polylactic acid-based resin, cyclic polyolefin resin, and polyphenylene sulfide resin. Among these, cellulose-based resins are preferred, and triacetyl cellulose resin, polycarbonate resin, and polyethylene terephthalate resin are more preferred. These resins may be used alone or in combination of two or more.

[0062] The thickness of the resin film is not particularly limited, but is preferably 20 to 150 μm, more preferably 40 to 80 μm.

[0063] When a resin film is used as the transparent substrate 10, one embodiment may be configured such that a hard coat layer (not shown) is disposed on the transparent substrate 10, and the multilayer film 30 is disposed thereon.

[0064] Furthermore, in another embodiment, it is also preferable to apply an anti-glare treatment to the main surface of the resin film on which the multilayer film is formed. In this case, an anti-glare layer (not shown) may be disposed on the hard coat layer, and the multilayer film 30 may be disposed on top of that.

[0065] The hard coat layer can be formed by applying a polymer resin solution. The anti-glare layer is formed by forming an uneven shape on one side of the film to increase haze and impart anti-glare properties. As with the hard coat layer, the anti-glare layer can be applied by applying a polymer resin solution. The anti-glare layer composition constituting the anti-glare layer is formed by dispersing at least a particulate substance that itself has anti-glare properties in a solution in which a polymer resin is dissolved as a binder.

[0066] Examples of the particulate substance having antiglare properties include inorganic fine particles such as silica, clay, talc, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, titanium oxide, synthetic zeolite, alumina, and smectite, as well as organic fine particles made of styrene resin, urethane resin, benzoguanamine resin, silicone resin, and acrylic resin.

[0067] Furthermore, the polymer resin used as the binder for the hard coat layer and the anti-glare layer may be, for example, a polymer resin made of a polyester resin, an acrylic resin, an acrylic urethane resin, a polyester acrylate resin, a polyurethane acrylate resin, an epoxy acrylate resin, or a urethane resin.

[0068] (Method for manufacturing a transparent substrate with a multilayer film) The above-mentioned multilayer film can be formed on the main surface of the transparent substrate by a known film formation method such as sputtering, vacuum deposition, coating, etc. That is, it is preferable to form each layer constituting the multilayer film on the main surface of the transparent substrate in accordance with the stacking order by a known film formation method such as sputtering, vacuum deposition, coating, etc.

[0069] Examples of sputtering methods for depositing a dielectric multilayer film include reactive sputtering using DC sputtering, DC pulse sputtering, AC sputtering, and the like, and digital sputtering.

[0070] For example, reactive sputtering is a method in which gas ion atoms collide with the surface of a dielectric material or a metal material, and the sputtered atoms that are ejected deposit and react with reactive gases such as oxygen, carbon dioxide, or nitrogen that are optionally contained in a rare gas such as argon, thereby forming a continuous dielectric film that is an oxide or nitride.

[0071] For example, digital sputtering differs from reactive sputtering, which directly forms the dielectric material mentioned above, in that it first forms an ultrathin metal film by sputtering, then oxidizes it by irradiating it with oxygen plasma, oxygen ions, or oxygen radicals, and repeats this process in the same chamber to form a thin film of metal oxide. In this case, the film-forming molecules are metal when deposited on the substrate, so they are presumably more ductile than metal oxide films. Therefore, even with the same energy, the film-forming molecules are more likely to rearrange, resulting in a denser, smoother film.

[0072] The method for forming the silicon oxide layer and the metal oxide layer is not particularly limited, and they can be formed by the methods described above, etc., but methods for adjusting the degree of oxidation of each layer include, for example, in the case of digital sputtering, adjusting the flow rate of oxygen gas during oxidation or the intensity of the power applied to the oxygen gas.

[0073] Furthermore, from the viewpoint of suppressing changes in transmittance due to the permeation of external oxygen gas or water vapor in high-temperature and high-temperature / high-humidity environments, it is preferable that the density of each layer in the multilayer film is relatively high. The method for adjusting the density of each layer is not particularly limited, but for example, in the case of a digital sputtering method, adjusting the pressure during film formation is an example. More specifically, in the case of a digital sputtering method, the pressure during film formation of the silicon oxide layer is preferably, for example, 0.05 to 1.0 Pa, and the pressure during film formation of the metal oxide layer is preferably, for example, 0.05 to 1.0 Pa.

[0074] In the transparent substrate with a multilayer film according to this embodiment, the multilayer film may be provided on at least one main surface of the transparent substrate, but may be provided on both main surfaces of the transparent substrate as required.

[0075] (Anti-fouling film) The multilayer film-coated transparent substrate according to this embodiment may further have an anti-fouling film (also referred to as an "anti-finger print (AFP) film") on the multilayer film in order to protect the outermost surface of the film. The anti-fouling film may be composed of, for example, a fluorine-containing organosilicon compound. The fluorine-containing organosilicon compound is not particularly limited as long as it can impart anti-fouling properties, water repellency, and oil repellency, and examples thereof include fluorine-containing organosilicon compounds having one or more groups selected from the group consisting of a perfluoropolyether group, a perfluoroalkylene group, and a perfluoroalkyl group. The perfluoropolyether group is a divalent group having a structure in which perfluoroalkylene groups and etheric oxygen atoms are alternately bonded.

[0076] In addition, commercially available fluorine-containing organosilicon compounds having one or more groups selected from the group consisting of perfluoropolyether groups, perfluoroalkylene groups, and perfluoroalkyl groups, such as KP-801 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), KY-178 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), KY-130 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), KY-185 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), OPTOOL (registered trademark) DSX, and OPTOOL AES (all trade names, manufactured by Daikin Industries, Ltd.), can be preferably used.

[0077] The antifouling film is preferably laminated on the above-mentioned multilayer film, which is an antireflection film. When a multilayer film is formed on both main surfaces of a glass substrate or a resin substrate, the antifouling film can be formed on both multilayer films, but it may also be configured so that the antifouling film is laminated on only one of the surfaces. This is because the antifouling film only needs to be provided in a location where there is a possibility of contact with a human hand, etc., and can be selected depending on the application, etc.

[0078] The transparent substrate with a multilayer film according to this embodiment is suitable as a cover glass for an image display device, particularly as a cover glass for an image display device mounted on a vehicle, such as an image display device for a navigation system mounted on a vehicle. That is, the present invention also relates to an image display device including the above-described transparent substrate with a multilayer film. In the image display device according to this embodiment, preferred aspects of the transparent substrate with a multilayer film are the same as those described above. [Example]

[0079] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. Examples 2 to 5 and 10 to 12 are working examples, and Examples 1 and 6 to 9 are comparative examples.

[0080] A multilayer film was formed on one main surface of a transparent substrate by the following method to prepare a transparent substrate with a multilayer film: A 40 μm-thick triacetyl cellulose resin film (hereinafter referred to as TAC film) was used as the transparent substrate.

[0081] In each example, the metal oxide layer was formed by the following method: a target made by mixing niobium and molybdenum in a weight ratio of 60:40 and sintering was used in a digital sputtering method. A metal film of a minute thickness was formed using argon gas, and immediately thereafter, it was oxidized using oxygen gas. This process was repeated at high speed to form a metal oxide layer of MoNbO. y A layer was deposited.

[0082] In each example, the silicon oxide layer was formed by the following method: a silicon target was used in a digital sputtering method, and silicon oxide layers were formed by rapidly repeating the process of forming a silicon film with argon gas and then immediately oxidizing it with oxygen gas. x )] was deposited.

[0083] (Example 1) On one main surface of a transparent substrate that had been subjected to antiglare treatment, the following dielectric layers (1) to (4) were formed in this order as a multilayer film. Dielectric layer (1): Metal oxide layer (MoNbO y layer, 9nm) Dielectric layer (2): Silicon oxide layer (SiO x layer, 36nm) Dielectric layer (3): Metal oxide layer (MoNbO y layer, 105nm) Dielectric layer (4): silicon oxide layer (SiO x layer, 80nm) Here, the discharge power ("DC" in Table 1) applied to the target during deposition of the metal oxide layer was 3.4 kW, the flow rate of argon gas (Ar) was 300 sccm, the flow rate of oxygen gas (O2) was 1200 sccm, and the discharge power of ECR ​​was 900 W. At this time, the pressure was 0.36 Pa. At this time, the discharge power applied to the target during deposition of the silicon oxide layer was 6.0 kW, the flow rate of argon gas (Ar) was 100 sccm, the flow rate of oxygen gas (O2) was 900 sccm, and the discharge power of ECR ​​was 1400 W. At this time, the pressure was 0.12 Pa.

[0084] Next, an antifouling film (AFP) was formed to a thickness of 4 nm on the dielectric layer (4) by the following method, to obtain a transparent substrate with a multilayer film. KY-185 (product name, manufactured by Shin-Etsu Chemical Co., Ltd.), a fluorine-containing organosilicon compound, was placed in a metal crucible (evaporation source) and evaporated by heating at 230-350°C. The evaporated particles were evaporated and diffused into a vacuum chamber containing a substrate, where they adhered to the substrate surface. A 4-nm thick antifouling film was formed while monitoring the evaporation rate using a quartz crystal oscillator.

[0085] (Examples 2 to 9) Metal oxide layer (MoNbO y layer) and silicon oxide layer (SiO x Dielectric layers (1) to (4) were formed as a multilayer film in the same manner as in Example 1, except that the film formation conditions for the dielectric layers (1) to (4) were set as shown in Table 1. Next, an antifouling film similar to that described above was formed thereon to a thickness of 4 nm, thereby obtaining a transparent substrate with a multilayer film.

[0086] (Example 10) Dielectric layers (1) to (4) and an antifouling film were formed in the same manner as in Example 1, except that the film-forming conditions for the metal oxide layer and silicon oxide layer were changed as shown in Table 1, to obtain a transparent substrate with a multilayer film. However, the film-forming conditions for the dielectric layer (2) were changed to "SiO x The conditions for forming the dielectric layer (4) are as shown in Table 1 under "SiO x The conditions shown in the lower row of the "Example 10" column were used. That is, in Example 10, the following dielectric layers (1) to (4) were formed in this order as a multilayer film. Next, a 4 nm thick antifouling film similar to that described above was formed thereon to obtain a transparent substrate with a multilayer film. Dielectric layer (1): Metal oxide layer (MoNbO y layer, 9nm) Dielectric layer (2): Silicon oxide layer (SiO x1 Layer, 36nm, deposition conditions (upper row) Dielectric layer (3): Metal oxide layer (MoNbO y layer, 105nm) Dielectric layer (4): silicon oxide layer (SiO x2 layer, 80 nm, deposition conditions (lower row)

[0087] (Example 11) Dielectric layers (1) to (3) were formed in the same manner as in Example 1, except that the film-forming conditions for the metal oxide layer and silicon oxide layer were changed as shown in Table 1. However, the film-forming conditions for the dielectric layer (2) were changed as shown in Table 1 under "SiO x The conditions in the upper row of the "Example 11" column were used. x A 40 nm silicon oxide layer was formed under the conditions in the upper row of column "Example 11," and then a 40 nm silicon oxide layer was formed as a dielectric layer (4-2) under the conditions in the lower row. That is, in Example 11, the following dielectric layers (1), (2), (3), (4-1), and (4-2) were formed in this order as a multilayer film. Next, a 4 nm antifouling film similar to that described above was formed thereon to obtain a transparent substrate with a multilayer film. Dielectric layer (1): Metal oxide layer (MoNbO y layer, 9nm) Dielectric layer (2): silicon oxide layer (SiO x1 Layer, 36nm, deposition conditions (upper row) Dielectric layer (3): Metal oxide layer (MoNbO y layer, 105nm) Dielectric layer (4-1): silicon oxide layer (SiO x1 layer, 40nm, film formation conditions (upper row) Dielectric layer (4-2): silicon oxide layer (SiO x2 layer, 40nm, deposition conditions)

[0088] (Example 12) Dielectric layers (1) and (2) were formed in the same manner as in Example 1, except that the film-forming conditions for the metal oxide layer and silicon oxide layer were changed as shown in Table 1. However, the dielectric layer (1) was formed using the "MoNbO y The dielectric layer (3'-1) was formed under the conditions shown in the upper row of the "Example 12" column. y A 10 nm metal oxide layer was formed in the same manner as above, except that the conditions in the middle row of column "Example 12" were used. Then, an 85 nm metal oxide layer was formed as dielectric layer (3) under the conditions in the lower row. Another 10 nm metal oxide layer was formed on top of this as dielectric layer (3'-2) under the conditions in the middle row, and an 80 nm silicon oxide layer was formed as dielectric layer (4) under the film-forming conditions listed in Table 1. That is, in Example 12, the following dielectric layers (1), (2), (3'-1), (3), (3'-2), and (4) were formed in this order as a multilayer film. Next, a 4 nm antifouling film similar to that described above was formed on top of this to obtain a transparent substrate with a multilayer film. Dielectric layer (1): Metal oxide layer (MoNbO y1 layer, 9 nm, deposition conditions (top row) Dielectric layer (2): silicon oxide layer (SiO x layer, 36nm) Dielectric layer (3'-1): Metal oxide layer (MoNbO y2 layer, 10nm, deposition conditions middle) Dielectric layer (3): Metal oxide layer (MoNbO y3 layer, 85nm, deposition conditions) Dielectric layer (3'-2): Metal oxide layer (MoNbO y2 layer, 10nm, deposition conditions middle) Dielectric layer (4): silicon oxide layer (SiO xlayer, 80nm)

[0089] (optical constant) A single film (a film consisting of only one layer) of a silicon oxide layer or metal oxide layer with a thickness of 300 nm or more was fabricated on a glass substrate under the same film-forming conditions as when each dielectric layer constituting the multilayer film of each example was formed, and spectroscopic measurements were performed. The optical constants were calculated from the obtained spectroscopic spectra. y The optical constants of the silicon oxide layer (SiO x As the optical constant of the silicon oxide layer, the refractive index n at a wavelength of 550 nm is shown in Table 1. The extinction coefficient k at a wavelength of 550 nm of the silicon oxide layer was almost 0 in all examples.

[0090] (Heat and humidity resistance test) Using the obtained transparent substrate with a multilayer film, the spectral transmittance was measured using a spectrophotometer (manufactured by Shimadzu Corporation, product name: SolidSpec-3700) for the transparent substrate with a multilayer film before and after 500 hours in a reliability test tank at a temperature of 85°C and a humidity of 85%RH, and the luminous transmittance (stimulus value Y specified in JIS Z 8701:1999) was calculated. The change in luminous transmittance, ΔTv, was calculated from the luminous transmittance before and after 500 hours. An absolute value of ΔTv of 2.0 or less was evaluated as "pass", and an absolute value of more than 2.0 was evaluated as "fail".

[0091] (Heat resistance test) Using the obtained transparent substrate with a multilayer film, the spectral transmittance was measured using a spectrophotometer (manufactured by Shimadzu Corporation, product name: SolidSpec-3700) for the transparent substrate with a multilayer film before being placed in a reliability test tank at a temperature of 95°C and for the transparent substrate with a multilayer film 500 hours after being placed in the tank. The luminous transmittance (stimulus value Y specified in JIS Z 8701:1999) was calculated, and the change in luminous transmittance ΔTv was calculated from the luminous transmittance before being placed in the tank and the luminous transmittance after 500 hours had passed. An absolute value of ΔTv of 2.0 or less was evaluated as "pass", and an absolute value of more than 2.0 was evaluated as "fail". In the "Judgment" column of Table 1, examples that passed both the moist heat resistance test and the heat resistance test were rated as "pass", and examples that failed either or both were rated as "fail".

[0092] [Table 1]

[0093] As shown in Table 1, the transparent substrates with multilayer films of Examples 2 to 5 and Examples 10 to 12, which are working examples, showed relatively small changes in transmittance before and after the heat resistance test and the moist heat resistance test, and were excellent in suppressing changes in transmittance under high temperature environments and high temperature and high humidity environments.

[0094] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2021-030879) filed on February 26, 2021, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0095] 10 Transparent substrate 20 Transparent substrate with multilayer film 30 Multilayer film 32, 33, 34 Dielectric layers

Claims

1. a multilayer film in which at least two layers having refractive indices different from each other are laminated on at least one of the main surfaces of a transparent substrate having two main surfaces, a layer mainly composed of a mixed oxide of Mo and Nb and having an extinction coefficient k of greater than 0.004 at a wavelength of 550 nm as a first metal oxide layer; When the second metal oxide layer is a layer mainly composed of a mixed oxide of Mo and Nb and having an extinction coefficient k of 0.004 or less at a wavelength of 550 nm, the multilayer film includes the first metal oxide layer; At least one of the first metal oxide layers is sandwiched between two of the second metal oxide layers, A transparent substrate with a multilayer film, wherein the second metal oxide layers sandwiching the first metal oxide layer each have a film thickness of 8 nm or more.

2. the multilayer film further comprises a silicon oxide layer; 2. The transparent substrate with a multilayer film according to claim 1, wherein the content of elements in group B in the first metal oxide layer is less than 80 mass% of the total of elements in group A consisting of Mo and W and elements in group B consisting of Si, Nb, Ti, Zr, Ta, Al, Sn, and In.

3. 3. The transparent substrate with a multilayer film according to claim 1, further comprising an antifouling film on the multilayer film.

4. 4. The transparent substrate with a multilayer film according to claim 1, wherein the transparent substrate is a glass substrate or a resin substrate.

5. 4. The transparent substrate with a multilayer film according to claim 1, wherein the transparent substrate is a laminate composed of a glass substrate and a resin substrate.

6. 6. The transparent substrate with a multilayer film according to claim 4, wherein the glass is chemically strengthened.

7. 7. The transparent substrate with a multilayer film according to claim 1, wherein the transparent substrate has a main surface on which the multilayer film is formed that is subjected to an anti-glare treatment.

8. An image display device comprising the transparent substrate with a multilayer film according to any one of claims 1 to 7.

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