Multilayer film, optical member having multilayer film, and method for manufacturing

Abstract

Provided are: a multilayer film which exhibits a sufficient self-cleaning function on the surface by means of a photocatalyst reaction even when the film thickness of a low-refractive-index layer on the surface is made to be equal to or greater than a specific thickness in order to reduce the reflectivity of light; the hydrophilicity can be maintained for a long time in a dark place. A multilayer film, an optical member having the multilayer film, and a method for manufacturing the multilayer film, the multilayer film being provided on a glass, a resin, or the like, and a layer containing a specific silicon oxide or a layer containing a specific magnesium fluoride on the layer containing the specific cerium oxide directly or via another layer.

Description

Technical Field

[0001] The present disclosure relates to a multilayer film having excellent self-cleaning properties and hydrophilicity, an optical component having the multilayer film, and a method for producing the multilayer film. Background Art

[0002] Optical components such as optical lenses, reflectors, and filters have films formed of inorganic materials to increase or decrease the transmittance and reflectance of light. Films formed of inorganic materials generally have high surface free energy just after film formation, so they have high hydrophilicity. However, due to the attachment of dirt from spontaneous reactions, people or the environment, the surface free energy decreases in a short period of time, and the hydrophilicity decreases.

[0003] For example, when the hydrophilicity of the surface of optical products used outdoors, such as optical products used in automobiles, surveillance cameras, eyeglass lenses, and their protective covers decreases, if water droplets adhere to the surface, the field of vision may be poor, and the functions of the optical products and protective covers may not be fully exerted.

[0004] As a solution to the above-mentioned problems, a hydrophilic film of a silicon dioxide film is formed on a crystalline titanium dioxide film (Patent Document 1, Patent Document 2, Non-Patent Document 1). When near-ultraviolet light irradiates the surface of crystalline titanium dioxide, active oxygen is generated by the photocatalytic function, and the generated active oxygen decomposes the organic matter on the surface of the hydrophilic film. As a result, the hydrophilicity of the hydrophilic film is restored, and the dirt is washed away by rainfall and self-cleansed. In addition, it is known that by configuring silicon dioxide on titanium dioxide, even if the light irradiation is stopped, it will not become hydrophobic in a short time like a thin film of titanium dioxide alone, and the hydrophilicity will last for 1 to 2 weeks even in the dark.

[0005] However, when the silicon dioxide film formed on the crystalline titanium dioxide film is less than 50 nm, the refractive index of titanium dioxide is large, so there is a problem that the reflectivity increases and the transmittance decreases. Therefore, even if it can be applied to vehicle rearview mirrors, etc., which are not affected by the increase in reflectivity, there is a problem that it is not suitable for optical parts such as lenses with anti-reflection films.

[0006] In addition, when the silicon dioxide film on the surface formed on the crystalline titanium dioxide film is 50 nm or more, there is a problem that the self-cleaning function using the photocatalytic reaction is not fully demonstrated. Furthermore, the hydrophilicity maintenance performance in the dark is improved compared with the case of only crystalline titanium dioxide, but there is a problem that it is not sufficient.

[0007] In addition, when a crystalline titanium dioxide layer is used as a photocatalyst, in order to crystallize a thin film composed of titanium dioxide, the thin film and the substrate on which the thin film is disposed must sometimes be heated to a high temperature, and there is a problem that a resin substrate with low heat resistance cannot be used. Some of the titanium dioxide film formation based on the wet process does not require high-temperature heating. However, when the wet process is used, there are problems such as the difficulty of controlling a fine film thickness of 1 nm, forming a thin film with a uniform film thickness, and forming a film on a substrate other than a substrate of a simple shape such as a flat plate, and there are also inherent problems such as a short storage period of the coating liquid.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 09-057912

[0011] Patent Document 2: Japanese Patent Application Publication No. 2000-053449

[0012] Non-patent literature

[0013] Non-patent document 1: Journal of the Ceramic Society of Japan 110[5]450-454(2002) Summary of the invention

[0014] Problems to be solved by the invention

[0015] Considering the application to optical components, it is desirable to have a multilayer film that can fully demonstrate the self-cleaning function using a photocatalytic reaction even when the film thickness of the low refractive index layer is increased in order to design the low refractive index layer on the surface of the optical component as an anti-reflection film. In addition, it is desirable to have a multilayer film that can maintain hydrophilicity for a longer period of time in a dark place.

[0016] The present disclosure is completed in view of the above-mentioned problems, and provides a multilayer film that can fully exhibit the self-cleaning function using photocatalytic reaction on the surface even when the film thickness of the low refractive index layer on the surface is made to be greater than a specific thickness in order to reduce the reflectivity of light, and can also maintain hydrophilicity for a long time even in the dark, an optical component having the above-mentioned multilayer film, and a method for manufacturing the above-mentioned multilayer film.

[0017] Solutions to Solve Problems

[0018] The multilayer film disclosed in the present invention is characterized in that it comprises: a layer containing cerium oxide; and a layer containing silicon oxide or a layer containing magnesium fluoride directly on the layer containing cerium oxide or via other layers, wherein the layer containing cerium oxide contains cerium oxide composed of a cubic polycrystalline structure, the film thickness of the layer containing cerium oxide is not less than 70nm and not more than 300nm, the film thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is not less than 50nm and not more than 240nm, and the refractive index of the layer containing silicon oxide and the layer containing magnesium fluoride at a wavelength of 500nm is not more than 1.65.

[0019] Furthermore, the multilayer film of the present disclosure is characterized in that a layer containing silicon dioxide is provided directly on the layer containing silicon oxide or the layer containing magnesium fluoride or via another layer, and the film thickness of the layer containing silicon dioxide is 30 nm or less.

[0020] In addition, the multilayer film disclosed in the present invention is characterized in that there is a layer composed of a first metal oxide between the layer containing the cerium oxide and the layer containing the silicon oxide or the layer containing the magnesium fluoride, the layer composed of the first metal oxide contains a metal oxide composed of a polycrystalline structure, and the film thickness of the layer composed of the first metal oxide is greater than 0.5 nm and less than 15 nm.

[0021] In addition, the multilayer film disclosed in the present invention is characterized in that there is a layer composed of a second metal oxide between the layer containing the silicon oxide or the layer containing the magnesium fluoride and the layer containing the silicon dioxide, the layer composed of the second metal oxide contains a metal oxide composed of a polycrystalline structure, and the film thickness of the layer composed of the second metal oxide is greater than 0.5 nm and less than 7 nm.

[0022] Furthermore, the optical component of the present disclosure is characterized by having the above-mentioned multilayer film of the present disclosure.

[0023] In addition, the method for manufacturing a multilayer film disclosed in the present invention is characterized in that it includes: forming a layer containing cerium oxide directly on a substrate or via other layers by a vacuum deposition method; and forming a layer containing silicon oxide or a layer containing magnesium fluoride directly on the layer containing the cerium oxide or via other layers by a vacuum deposition method, wherein the layer containing the cerium oxide contains cerium oxide composed of a cubic polycrystalline structure, the film thickness of the layer containing the cerium oxide is greater than 70nm and less than 300nm, the film thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is greater than 50nm and less than 240nm, and the refractive index of the layer containing silicon oxide and the layer containing magnesium fluoride at a wavelength of 500nm is less than 1.65.

[0024] Effects of the Invention

[0025] According to one method of the present disclosure, a multilayer film, an optical component having the multilayer film, and a method for manufacturing the multilayer film can be obtained. Even when the thickness of the low refractive index layer on the surface is made to be greater than a specific thickness in order to reduce the reflectivity of light, the multilayer film can fully exhibit a self-cleaning function utilizing a photocatalytic reaction on the surface, and can maintain hydrophilicity for a long time even in a dark place. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic cross-sectional view showing the structure of the first embodiment of the multilayer film according to the present disclosure.

[0027] Figure 2 It is a schematic cross-sectional view showing the structure of a second embodiment of the multilayer film according to the present disclosure.

[0028] Figure 3 It is a schematic cross-sectional view showing the structure of a third embodiment of the multilayer film according to the present disclosure.

[0029] Figure 4 It is a schematic cross-sectional view showing the structure of a fourth embodiment of the multilayer film according to the present disclosure.

[0030] Figure 5 It is a schematic cross-sectional view showing the structure of a fifth embodiment of the multilayer film according to the present disclosure.

[0031] Figure 6 It is a schematic cross-sectional view showing the structure of a sixth embodiment of the multilayer film according to the present disclosure.

[0032] Figure 7 This is a schematic diagram showing one embodiment of the optical component involved in the present disclosure.

[0033] Figure 8 This is a schematic diagram showing one embodiment of the optical component involved in the present disclosure. DETAILED DESCRIPTION

[0034] Hereinafter, preferred embodiments are described for the multilayer film, the optical component having the multilayer film, and the method for forming the multilayer film according to the present disclosure.

[0035] In addition, the present disclosure is not limited to the following embodiments.

[0036] In addition, in the present disclosure, unless otherwise specified, the description of [XX or more and YY or less] and [XX to YY] indicating a numerical range means a numerical range including the lower limit and the upper limit as endpoints. Moreover, when describing the numerical range in stages, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0037] In the present disclosure, "multilayer film" refers to a structure including two or more layers formed on the surface of a substrate. The multilayer film involved in the present disclosure can be provided on the substrate directly or through other layers. Hereinafter, the layers constituting the multilayer film are sometimes referred to as films.

[0038] In the present disclosure, "substrate" as an article refers to a solid object.

[0039] In the present disclosure, "optical component" refers to an optical component having the above-mentioned multilayer film. Examples of the optical component include filters, optical lenses, lighting lenses, optical films, optical prisms, eyeglass lenses, camera lenses, surveillance camera covers, vehicle camera covers, vehicle sensor covers, vehicle rearview mirrors, flat glass, focusing lenses, display cover glass, touch panels, and various films.

[0040] Before describing the multilayer film of the present disclosure in detail, the following description is first given for the purpose of understanding the present disclosure, which is a presumed mechanism of action that produces the effect. However, the following description is merely an assumption, and the present disclosure is not limited to the following assumption.

[0041] The inventors have found that when a layer containing cerium oxide having a cubic polycrystalline structure is disposed directly on a substrate or via other layers, and a layer containing magnesium fluoride or silicon oxide having a specific film thickness is disposed directly on the layer containing cerium oxide or via other layers, a function of restoring hydrophilicity utilizing the self-cleaning property of a photocatalyst is exhibited. The following is considered with respect to the aforementioned mechanism of action.

[0042] When the film of the photocatalyst that responds to near ultraviolet light is irradiated with near ultraviolet light, holes and electrons are generated by light excitation. When the generated holes and electrons can reach the surface of the film, a chemical reaction occurs, showing a recovery function of the hydrophilicity utilizing self-cleaning properties. However, in the case of forming a low-refractive index layer consisting of a specific film thickness exceeding 50nm on crystalline titanium dioxide, the holes and electrons generated by light excitation are blocked by their thickness and therefore cannot reach the surface of the multilayer film. Therefore, the holes and electrons are recombined and deactivated, so the recovery function of the hydrophilicity utilizing self-cleaning properties is not shown. On the other hand, in the case of forming a low-refractive index layer consisting of a film thickness exceeding 50nm on the layer containing cerium oxide disclosed in the present invention, compared with the case of forming a low-refractive index layer on crystalline titanium dioxide, the proportion of holes and electrons reaching the surface of the multilayer film increases and causes a chemical reaction, thereby showing a recovery function of the hydrophilicity based on self-cleaning properties. At the interface of the layer containing cerium oxide disclosed in the present invention and the upper layer connected to the layer containing cerium oxide, each layer has a region of mutual diffusion such as a compound or a mixture. In this region, trivalent and tetravalent cerium are easily mixed and coexist, and electrons generated by photoexcitation are easily retained, so holes and electrons may be difficult to recombine. In addition, since the cerium oxide contained in the layer containing cerium oxide has a cubic polycrystalline structure, it has high conductivity and has multiple interfaces, so holes and electrons are easy to move and may be difficult to recombine.

[0043] Furthermore, the present inventors have found that when a layer containing cerium oxide having a cubic polycrystalline structure is disposed directly on a substrate or via another layer, and a layer containing magnesium fluoride or silicon oxide is disposed on the upper side, the ability to maintain hydrophilicity in a dark place is dramatically improved. The following is considered as to the aforementioned mechanism of action.

[0044] When a layer containing cerium oxide of a cubic polycrystalline structure is exposed to ultraviolet rays or light with higher energy than ultraviolet rays, electrical energy, chemical energy, etc. are stored inside and at the interface of the cerium oxide. It is believed that the layer containing cerium oxide of the present disclosure supplies the stored energy to the surface side of the multilayer film, thereby maintaining the surface energy of the multilayer film at a high state, thereby improving the hydrophilicity in the dark. In particular, for the layer containing cerium oxide of the present disclosure formed by vacuum evaporation, since trivalent and tetravalent cerium are easily mixed and coexist, it is possible that it is easy to store energy.

[0045] <<First Implementation Method>>

[0046] Figure 1 1 is a schematic cross-sectional view showing a first embodiment of the multilayer film of the present disclosure disposed on a substrate. In this embodiment, a layer 13 containing cerium oxide of the present disclosure is formed on a substrate 11, and a layer 14 containing magnesium fluoride is formed on the layer 13 containing cerium oxide. In addition, Figures 1 to 6This is a diagram schematically showing the structure of the multilayer film in the present disclosure, and therefore, it is not a diagram showing the area, film thickness, etc. of each layer in an accurate ratio.

[0047] The substrate 11 will be described.

[0048] The substrate 11 can be made of glass, ceramic, resin, metal, etc. as long as it can be stacked to form other layers 12 and the layer 13 containing cerium oxide disclosed in the present invention. The shape of the substrate is not limited, for example, it can be a plane, a curved surface, a concave surface, a convex surface, and a film. In addition, the substrate 11 can also have a hard coating layer and a barrier layer. Furthermore, the size and thickness of the substrate 11 are not particularly limited, and can be appropriately set according to the purpose, etc.

[0049] The cerium oxide-containing layer 13 according to the present disclosure is described below. The cerium oxide-containing layer 13 according to the present disclosure is a layer containing cerium oxide (CeO x ) layer. In a layer composed of cerium oxide with a single crystal structure, cracks are easily generated in the film. In a layer composed of cerium oxide with an amorphous structure, the self-cleaning function of the photocatalyst and the ability to maintain hydrophilicity in the dark are significantly reduced.

[0050] In addition, the definition of "polycrystalline structure" in the present disclosure means that a characteristic peak of cerium oxide appears in X-ray diffraction (XRD) measurement of a film after film formation.

[0051] The film thickness of the layer 13 containing cerium oxide disclosed herein is 70 nm to 300 nm. When the film thickness of the layer 13 containing cerium oxide is less than 70 nm, the self-cleaning function of the photocatalyst and the ability to maintain hydrophilicity in the dark are significantly reduced. In addition, when the film thickness of the layer 13 containing cerium oxide exceeds 300 nm, cracks are easily generated, and sometimes the inhomogeneity and surface roughness become too large, which sometimes has an adverse effect on the optical properties.

[0052] The composition of cerium oxide in the cerium oxide-containing layer 13 of the present disclosure is preferably CeO x , x is 1.5 or more and 2.0 or less. If the composition of cerium oxide is CeO x When the value of x in the above range is within the above range, a film that is more transparent in the wavelength range from visible light to near infrared light can be obtained.

[0053] The content of cerium oxide in the cerium oxide-containing layer 13 of the present disclosure is preferably 85 mass % or more relative to the entire cerium oxide-containing layer 13. When the content of cerium oxide is 85 mass % or more, the ability to maintain hydrophilicity in a dark place is further improved.

[0054] The cerium oxide-containing layer 13 of the present disclosure may be disposed directly on the substrate 11 or may be disposed via another layer 12 described later.

[0055] The layer 14 containing magnesium fluoride involved in the present disclosure is described. The film thickness of the layer 14 containing magnesium fluoride is more than 50nm and less than 240nm. When the film thickness of the layer 14 containing magnesium fluoride is less than 50nm, the reflectivity of the multilayer film sometimes becomes too high. On the other hand, when the film thickness of the layer 14 containing magnesium fluoride exceeds 240nm, the self-cleaning function of the photocatalyst is sometimes not exerted on the surface of the multilayer film. In addition, the refractive index of the layer 14 containing magnesium fluoride is less than 1.65 at a wavelength of 500nm. When the refractive index of the layer 14 containing magnesium fluoride exceeds 1.65, the reflectivity of the multilayer film sometimes becomes too high.

[0056] The content ratio of magnesium fluoride in the total amount of substances constituting the magnesium fluoride-containing layer 14 is preferably 65 mass % or more. Within the above range, the ability to maintain hydrophilicity in a dark place is further improved.

[0057] Second Implementation Method

[0058] Figure 2 1 is a schematic cross-sectional view showing a second embodiment of the multilayer film of the present disclosure. In this embodiment, the multilayer film involved in the present disclosure can also be provided on another layer 12 provided on a substrate 11. That is, the second embodiment shows a structural example in which another layer 12 is formed on a substrate 11, and a layer 13 containing cerium oxide of the present disclosure is formed on the other layer 12, and a layer 15 containing silicon oxide is further formed on the layer 13 containing cerium oxide.

[0059] The substrate 11 and the cerium oxide-containing layer 13 of the present disclosure are as described in the above-mentioned first embodiment.

[0060] In this embodiment, the magnesium fluoride-containing layer 14 described in the first embodiment may be disposed instead of all or part of the silicon oxide-containing layer 15. The cerium oxide-containing layer 13 of the present disclosure may be disposed directly on the substrate 11 without interposing another layer 12 therebetween.

[0061] As the other layer 12, a layer containing a metal, a fluoride, an oxide, a carbide, or a nitride can be configured. As the other layer 12, specifically, a metal layer containing an element such as aluminum (Al), chromium (Cr), gold (Au), silver (Ag), copper (Cu), silicon (Si), germanium (Ge), titanium (Ti), or nickel (Ni), a layer containing a fluoride such as magnesium fluoride (MgF2) or calcium fluoride (CaF2), a layer containing silicon oxide (SiO x ), aluminum oxide (Al2O x ), yttrium oxide (Y2O x ), zirconium oxide (ZrO x ), hafnium oxide (HfOx ), zinc oxide (ZnO x ), tantalum oxide (Ta2O x ), niobium oxide (Nb2O x ), indium oxide (In2O x ), tin oxide (SnO x ), tungsten oxide (WOx), cerium oxide (CeOx), titanium oxide (TiO x ), lanthanum titanate (La x Ti y O z ), aluminum titanate (La x Al y O z ), a layer of oxides such as silicon dioxide (SiO2+Al2O3) with added aluminum oxide, a layer containing a nitride such as silicon nitride (Si3N4), a layer containing a carbide such as tungsten carbide (WC), etc. The other layer 12 may be a single layer or a multilayer of two or more layers. When the other layer 12 is a multilayer of two or more layers, the other layer 12 may be composed of a combination of multiple layers among the layers exemplified above. In addition, the other layer 12 may also be a layer containing a mixture of two or more of the compounds contained in the layers exemplified above.

[0062] There is no particular limitation on the method for forming the other layers 12. For example, dry film forming methods such as sputtering, vacuum deposition, and ion plating, and wet film forming methods such as dipping, coating, spraying, spin coating, barcoat, printing, and flow coating can be used.

[0063] By making the other layers 12 have a composition, refractive index, film thickness, number of layers, etc. that are suitable for the purpose and function, it can become a multilayer film with added specific functions such as an anti-reflection layer, a semi-reflective mirror layer, a light absorption layer, an anti-alkali diffusion layer, a bonding layer, an antistatic layer, a heating layer, etc.

[0064] The refractive index of the layer 15 containing silicon oxide is 1.65 or less at a wavelength of 500 nm. If it exceeds 1.65, the reflectivity of the multilayer film may become too high.

[0065] The layer 15 containing silicon oxide is a layer containing silicon oxide (SiO x ) layer. The content of silicon oxide in the silicon oxide-containing layer 15 is preferably 65 mass % or more relative to the entire silicon oxide-containing layer 15. If the content of silicon oxide in the silicon oxide-containing layer 15 is within the above range, the ability to maintain hydrophilicity in a dark place is further improved.

[0066] The silicon oxide-containing layer 15 preferably has a composition of SiO x, x is 1.5 or more and 2.0 or less. If the composition of silicon oxide is SiO x When the value of x in φ is within the above range, the refractive index of the layer 15 containing silicon oxide can be set to 1.65 or less. In addition, a film that is more transparent in the wavelength range from visible light to near infrared light can be obtained.

[0067] The silicon oxide-containing layer 15 includes silicon oxide (SiO x ) can also contain aluminum oxide. In this case, the content ratio of aluminum oxide in the layer 15 containing silicon oxide is preferably 0.1 mass % or more and 10 mass % or less relative to the entire layer 15 containing silicon oxide. The layer 15 containing silicon oxide contains 0.1 to 10 mass % of aluminum oxide, thereby maintaining the self-cleaning function of the multilayer film using a photocatalyst and the ability to maintain hydrophilicity in the dark, thereby improving the durability of the multilayer film such as scratch resistance and moisture resistance.

[0068] The silicon oxide-containing layer 15 includes silicon oxide (SiO x ) may also contain cerium oxide. In this case, the content ratio of cerium oxide in the layer 15 containing silicon oxide is preferably 0.1 mass % or more and 35 mass % or less relative to the entire layer 15 containing silicon oxide. The layer 15 containing silicon oxide contains 0.1 to 35 mass % of cerium oxide, thereby being able to improve the self-cleaning function using the photocatalyst while maintaining the hydrophilicity of the multilayer film.

[0069] 《Third Implementation Mode》

[0070] Figure 3 The schematic cross-sectional view shows a third embodiment of the multilayer film of the present disclosure provided on a substrate. The third embodiment shows a structural example in which a layer 13 containing cerium oxide of the present disclosure is formed on a substrate 11, a layer 14 containing magnesium fluoride is formed on the layer 13 containing cerium oxide, and a layer 16 containing silicon dioxide is formed on the layer 14 containing magnesium fluoride.

[0071] The substrate 11, the layer 13 containing cerium oxide of the present disclosure, and the layer 14 containing magnesium fluoride are as described in the first and second embodiments. In addition, the layer 15 containing silicon oxide described in the second embodiment may be configured instead of all or part of the layer 14 containing magnesium fluoride. In addition, the layer 13 containing cerium oxide of the present disclosure may be directly configured on the substrate 11, or may be configured via the other layer 12 described in the second embodiment.

[0072] The silicon dioxide-containing layer 16 of the present disclosure is described below. The multilayer film of the present disclosure preferably has a silicon dioxide-containing layer 16 having a film thickness of 30 nm or less on the upper side of the magnesium fluoride-containing layer 14 or the silicon oxide-containing layer 15. This can further improve the ability to maintain hydrophilicity in dark places.

[0073] The refractive index of the layer 16 containing silicon dioxide is preferably 1.65 or less at a wavelength of 500 nm. If the refractive index of the layer 16 containing silicon dioxide exceeds 1.65, the reflectivity of the multilayer film may become too high.

[0074] 《Fourth Implementation Mode》

[0075] Figure 4 The fourth embodiment is a schematic cross-sectional view showing a fourth embodiment of the multilayer film of the present disclosure disposed on a substrate. The fourth embodiment shows a structural example in which a layer 13 containing cerium oxide of the present disclosure is formed on a substrate 11, a layer 17 composed of a first metal oxide of the present disclosure is arranged on the layer 13 containing cerium oxide, and a layer 15 containing silicon oxide is formed on the layer 17 composed of the first metal oxide.

[0076] The substrate 11, the layer 13 containing cerium oxide of the present disclosure, and the layer 15 containing silicon oxide are as described in the first to third embodiments. In addition, the layer 14 containing magnesium fluoride described in the first embodiment may be configured instead of all or part of the layer 15 containing silicon oxide. In addition, the layer 13 containing cerium oxide of the present disclosure may be directly configured on the substrate 11, or may be configured via the other layer 12 described in the second embodiment.

[0077] The layer 17 composed of the first metal oxide involved in the present disclosure is described. The layer 17 composed of the first metal oxide preferably contains a metal oxide composed of a polycrystalline structure, and the film thickness of the layer 17 composed of the first metal oxide is greater than 0.5nm and less than 15nm. The multilayer film involved in the present disclosure is preferably configured with the layer 17 composed of the first metal oxide of the present disclosure between the layer 13 containing cerium oxide and the layer 14 containing magnesium fluoride or the layer 15 containing silicon oxide. The multilayer film involved in the present disclosure has such a structure, so that the hydrophilicity maintenance ability in the dark and the self-cleaning function using the photocatalyst are improved. The metal oxide contained in the layer 17 composed of the first metal oxide can be a simple oxide or a composite oxide. In addition, the layer 17 composed of the first metal oxide can contain not only one kind, but also two or more kinds of metal oxides.

[0078] The metal oxide contained in the layer 17 composed of the first metal oxide of the present disclosure is preferably composed of CeO x(x=1.5 or more and 2.0 or less) represented by cerium oxide or composed of CuO x (x=0.5 or more and 1.0 or less) represents copper oxide. By using these oxides, the ability to maintain hydrophilicity in a dark place and the self-cleaning function utilizing the photocatalyst can be further improved.

[0079] The thickness of the layer 17 composed of the first metal oxide of the present disclosure is preferably 0.5 nm or more and 15 nm or less. If the thickness of the layer 17 composed of the first metal oxide is within the above range, it will not have an adverse effect on the light transmittance, and can further improve the ability to maintain hydrophilicity in dark places and utilize the self-cleaning function of the photocatalyst.

[0080] 《Fifth Implementation Mode》

[0081] Figure 5 The fifth embodiment of the multilayer film of the present invention is schematically shown in a cross-sectional view. The fifth embodiment shows a structural example in which a layer 13 containing cerium oxide of the present invention is formed on a substrate 11, a layer 15 containing silicon oxide is formed on the layer 13 containing cerium oxide, a layer 18 composed of a second metal oxide of the present invention is arranged on the layer 15 containing silicon oxide, and finally a layer 16 containing silicon dioxide is formed on the layer composed of the second metal oxide.

[0082] The substrate 11, the layer 13 containing cerium oxide of the present disclosure, and the layer 15 containing silicon oxide are as described in the first to fourth embodiments. In addition, the layer 14 containing magnesium fluoride described in the first embodiment may be configured instead of all or part of the layer 15 containing silicon oxide. In addition, the layer 13 containing cerium oxide of the present disclosure may be directly configured on the substrate 11, or may be configured via the other layer 12 described in the second embodiment.

[0083] The layer 18 composed of the second metal oxide having the polycrystalline structure involved in the present disclosure is described. The layer 18 composed of the second metal oxide preferably contains a metal oxide composed of a polycrystalline structure, and the film thickness of the layer 18 composed of the second metal oxide is not less than 0.5nm and not more than 7nm. The multilayer film involved in the present disclosure is preferably configured with the layer 18 composed of the second metal oxide between the layer 15 containing silicon oxide and the layer 16 containing silicon dioxide. The multilayer film involved in the present disclosure has such a structure, so that the self-cleaning function using the photocatalyst is further improved. The metal oxide contained in the layer 18 composed of the second metal oxide can be a simple oxide or a composite oxide. In addition, the layer 18 composed of the second metal oxide can contain not only one kind, but also two or more kinds of metal oxides.

[0084] In the fifth embodiment, a layer other than the layer 18 composed of the second metal oxide of the present disclosure may be arranged between the layer 15 containing silicon oxide and the layer 16 containing silicon dioxide. One or more layers containing various substances such as fluoride and nitride may be arranged within a range that does not adversely affect the ability to maintain hydrophilicity in dark places, the self-cleaning function using a photocatalyst, and the like.

[0085] The metal oxide contained in the layer 18 composed of the second metal oxide of the present disclosure is preferably composed of CeO x The cerium oxide of the present disclosure having a cubic polycrystalline structure represented by (x=1.5 or more and 2.0 or less) or having a composition of CuO x Copper oxide represented by (x=0.5 or more and 1.0 or less). By using these oxides, the self-cleaning function by the photocatalyst can be improved.

[0086] 《Sixth Implementation Method》

[0087] Figure 6 The sixth embodiment of the multilayer film of the present disclosure is schematically shown in a cross-sectional view. The sixth embodiment shows a structure example in which another layer 12 is formed on a substrate 11, followed by a layer 13 containing cerium oxide of the present disclosure, a layer 17 composed of a first metal oxide of the present disclosure, a layer 15 containing silicon oxide, a layer 18 composed of a second metal oxide of the present disclosure, and a layer 16 containing silicon dioxide in this order.

[0088] The substrate 11 and the layers are as described in the first to fifth embodiments. In addition, the layer 14 containing magnesium fluoride described in the first embodiment may be provided instead of all or part of the layer 15 containing silicon oxide.

[0089] In addition, each layer of the multilayer film of the present disclosure may contain other compounds or atoms within the scope that does not affect the present disclosure. That is, in addition to the impurities that inevitably exist in the composition of the present disclosure, other compounds or atoms may also be added as needed as long as they do not affect the present disclosure.

[0090] Optical components

[0091] Figure 7 as well as Figure 8 Each of the diagrams schematically shows a structure of an embodiment of an optical component of the present disclosure. Figure 7 The lens cover for monitoring camera is a lens cover in which the multilayer film of the present disclosure is formed on the surface of a dome-shaped resin substrate 21. Figure 8The glasses are composed of a spectacle lens 31 as one embodiment of the optical component of the present disclosure and a spectacle frame 32. The multilayer film of the present disclosure is formed on both surfaces of the spectacle lens 31.

[0092] The multilayer film disclosed in the present invention can be used as an optical film such as an anti-reflection film, various filter multilayer films, and optical reflector multilayer films. In addition, it can be used for optical filters, optical lenses, lighting lenses, optical films, optical prisms, eyeglass lenses, lenses for taking photos, covers for monitoring cameras, covers for car cameras, covers for car sensors, rearview mirrors for vehicles, flat glass, focusing lenses, cover glass for display screens, touch panels, and various films and other optical components, covers for protecting the optical components, etc. In addition, by coating a coating having a layer having a composition, refractive index, film thickness, number of layers, etc. that meets the purpose and function on the surface other than the surface on which the above-mentioned layers are provided on the substrate 11, it can become an optical component with specific functions such as a reflector layer, a semi-reflector layer, a light absorption layer, a transparent heating layer, and an anti-reflection layer.

[0093] 《Method for producing multilayer film》

[0094] Furthermore, the method for producing a multilayer film of the present disclosure is characterized by being formed by a method including at least the following steps (A) and (B).

[0095] (A) Step of forming the layer 13 containing cerium oxide directly on the substrate or via another layer by vacuum deposition

[0096] (B) A step of forming a layer 14 containing magnesium fluoride or a layer 15 containing silicon oxide on the layer 13 containing cerium oxide of the present disclosure by a vacuum deposition method.

[0097] The layer 13 containing cerium oxide formed by the above step (A) contains cerium oxide composed of a cubic polycrystalline structure, and the film thickness of the layer 13 containing cerium oxide formed by the above step (A) is 70 nm to 300 nm. In addition, the film thickness of the layer 14 containing silicon oxide and the layer 15 containing magnesium fluoride formed by the above step (B) is 50 nm to 240 nm, and the refractive index of the layer 14 containing silicon oxide and the layer 15 containing magnesium fluoride formed by the above step (B) at a wavelength of 500 nm is 1.65 or less.

[0098] The temperature of the substrate during vacuum deposition is preferably a temperature at which cerium oxide crystallizes, and is generally selected within a range of 0°C to 500°C, although it may depend on the heat resistance temperature of the substrate used and other film-forming conditions.

[0099] The evaporation method in vacuum coating is not limited as long as it is a method for evaporating the film forming material. For example, in the evaporation method, evaporation schemes such as electron gun, resistance heating, and laser can be applied. In addition, in the above evaporation schemes, ion assistance, plasma assistance, etc. can be used in combination as needed.

[0100] By the above-mentioned method, the multilayer film of the present disclosure can be suitably produced.

[0101] Example

[0102] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples.

[0103] The materials used for the multilayer film preparation and evaluation in the examples are described below.

[0104] (Base material)

[0105] Flat plates of the materials listed below were used as substrates. In addition, when the substrate temperature during vapor deposition was 350° C., two substrates, borosilicate glass and synthetic quartz, were used. In the case of substrate temperatures other than this, all of the following substrates were used.

[0106] Borosilicate glass: Thickness 3mm

[0107] Synthetic quartz: thickness 3mm

[0108] Polycarbonate resin: thickness 2mm

[0109] Polymethyl methacrylate resin: thickness 2mm

[0110] (Film-forming material)

[0111] The materials listed below were used.

[0112] Ce: Granular, purity 99.9%

[0113] ·CeO2: cylindrical, purity 99.9%

[0114] ·La2O3: cylindrical, purity 99.9%

[0115] ·Sm2O3: cylindrical, purity 99.9%

[0116] ·SiO: Granular, purity 99.9%

[0117] ·SiO2: Granular, purity 99.9%

[0118] ·Al2O3: granular, purity 99.9%

[0119] MgF2: Granular, purity 99.9%

[0120] CaF2: Granular, purity 99.9%

[0121] ·ZrO2: cylindrical, purity 99.9%

[0122] Ti3O5: Granular, purity 99.9%

[0123] ·CuO: Granular, purity 99.9%

[0124] Cu2O: Granular, purity 99.9%

[0125] O2: gas, purity 99.999%

[0126] (Reagents, etc.)

[0127] Pure water

[0128] ·Stearic acid: JIS K8585 special grade, purity 99.9%

[0129] ·Heptane: JIS K9701 special grade, purity 99.9%

[0130] (Production of multilayer films)

[0131] The common film forming methods and film forming conditions of the examples and comparative examples in the preparation of the multilayer film are described. A vacuum coating device (dome diameter Φ900 mm, evaporation distance 890 mm) was used as the film forming device. The aforementioned film forming materials and various clean substrates were placed in the device, and the device was evacuated until the vacuum degree (7.0×10 -4 Pa). The substrate temperature during film formation is above -10°C and below 350°C. Then, the film-forming material is formed into a multilayer film as listed in Table 1 on the placed substrate by vacuum coating to obtain a test piece. At this time, each layer is evaporated at a evaporation rate of 0.5nm / sec. The film composed of two components such as CeO2+Al2O3 and SiO2+Al2O3 is formed by a binary evaporation method in which two types of film-forming materials are respectively placed on two heating sources and evaporated simultaneously. In addition, in each of Examples 1 to 47 and Comparative Examples 1 to 8, there is essentially no difference between the multilayer films obtained by changing the type of substrate, so only one example is recorded in Table 1. In addition, "polycrystalline" in Table 1 refers to a cubic polycrystalline structure.

[0132] Hereinafter, individual conditions of each example and comparative example in the production of a multilayer film will be described.

[0133] [Examples 1 to 3]

[0134] CeO2 films were formed on various substrates heated to 350° C. using CeO2 as a film-forming material. MgF2 films were then formed thereon using MgF2 as a film-forming material, thereby producing multilayer films. Other film-forming conditions were as described in (Production of Multilayer Films).

[0135] [Examples 4 to 6]

[0136] CeO2 films were formed on various substrates heated to 350° C. using CeO2 as a film-forming material. SiO2 films were then formed on the substrates using SiO2 as a film-forming material to produce multilayer films. Other film-forming conditions were as described in (Production of Multilayer Films).

[0137] [Example 7]

[0138] CeO2 and Ce were used as film-forming materials to form CeO on various substrates heated to 350°C. 1.8 Then, a MgF2 film is formed on the MgF2 film as a film-forming material, thereby producing a multilayer film. Other film-forming conditions are as described in (Production of a Multilayer Film).

[0139] [Example 8]

[0140] CeO2 and Ce were used as film-forming materials to form CeO on various substrates heated to 350°C. 1.8 Then, a SiO2 film is formed on the SiO2 film using SiO2 as a film-forming material, thereby producing a multilayer film. Other film-forming conditions are as described in (Production of a Multilayer Film).

[0141] [Example 9]

[0142] On various substrates heated to 350°C, CeO2 and La2O3 were used as film-forming materials. 1.5 This film was formed so that the (85%) + La2O3 (15%) film had the composition described in Table 1. Then, a MgF2 film was formed thereon using MgF2 as a film-forming material to produce a multilayer film. The other film-forming conditions were as described in (Production of Multilayer Film).

[0143] [Example 10]

[0144] On various substrates heated to 350°C, CeO2 and Al2O3 were used as film-forming materials. 1.8 +Al2O3 film was formed so as to have the composition described in Table 1. Then, SiO2 film was formed thereon using SiO2 as a film forming material to produce a multilayer film. Other film forming conditions were as described in (Production of Multilayer Film).

[0145] [Example 11]

[0146] On various substrates heated to 350°C, CeO2 and Sm2O3 were used as film-forming materials. 1.5 +Sm2O3 film was formed so that it had the composition described in Table 1. Then, SiO2 film was formed thereon using SiO2 as a film forming material to produce a multilayer film. Other film forming conditions were as described in (Production of Multilayer Film).

[0147] [Examples 12 to 17]

[0148] CeO2 films were formed on various substrates heated to 350°C using CeO2 as a film-forming material. Then, SiO2 and Al2O3 were used as film-forming materials to form a SiO2+Al2O3 film having the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0149] [Examples 18 to 23]

[0150] CeO2 films were formed on various substrates heated to 350° C. using CeO2 as a film-forming material. Next, SiO2 and CeO2 were used as film-forming materials to form a SiO2+CeO2 film having the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0151] [Examples 24-25]

[0152] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, MgF2 was used as a film-forming material to form a MgF2 film thereon. Furthermore, SiO2 was used to form a SiO2 film thereon, thereby producing a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0153] [Examples 26-27]

[0154] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, SiO2 and Al2O3 were used as film-forming materials to form a film such that the SiO2+Al2O3 film had the composition described in Table 1. Furthermore, SiO2 was used to form a SiO2 film on the substrate to produce a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0155] [Examples 28 to 30]

[0156] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, SiO2 and CeO2 were used as film-forming materials to form a film such that the SiO2+CeO2 film had the composition described in Table 1. Furthermore, SiO2 was used to form a SiO2 film on the substrates to produce a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0157] [Examples 31 to 33]

[0158] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, CuO was used as a film-forming material to form a CuO film thereon. Furthermore, SiO2 and CeO2 were used as film-forming materials thereon to form a SiO2+CeO2 film in such a manner that the film had the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0159] [Example 34]

[0160] On various substrates heated to 350°C, CeO2 and La2O3 were used as film-forming materials. 1.5 The film was formed in such a way that the SiO2+CeO3 film had the composition described in Table 1. Then, a CeO2 film was formed thereon using CeO2 as a film-forming material. Furthermore, SiO2 and CeO2 were used as film-forming materials thereon, and the film was formed in such a way that the SiO2+CeO2 film had the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions are as described in (Production of Multilayer Film).

[0161] [Example 35]

[0162] On various substrates heated to 350°C, CeO2 and Al2O3 were used as film-forming materials. 1.8 The film was formed in such a way that the SiO2+CeO2 film had the composition described in Table 1. Then, a CeO2 film was formed thereon using CeO2 as a film-forming material. Furthermore, SiO2 and CeO2 were used thereon as film-forming materials, and the film was formed in such a way that the SiO2+CeO2 film had the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions are as described in (Production of Multilayer Film).

[0163] [Example 36]

[0164] On various substrates heated to 350°C, CeO2 and Sm2O3 were used as film-forming materials. 1.5The film was formed in such a way that the SiO2+CeO2 film had the composition described in Table 1. Then, a CeO2 film was formed thereon using CeO2 as a film-forming material. Furthermore, SiO2 and CeO2 were used thereon as film-forming materials, and the film was formed in such a way that the SiO2+CeO2 film had the composition described in Table 1, thereby producing a multilayer film. Other film-forming conditions are as described in (Production of Multilayer Film).

[0165] [Examples 37 to 39]

[0166] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, SiO2 and CeO2 were used as film-forming materials to form the film in such a way that the SiO2+CeO2 film had the composition described in Table 1. Furthermore, CuO was used to form a CuO film on the film. Furthermore, SiO2 was used to form a SiO2 film on the film, thereby producing a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0167] [Examples 40 to 42]

[0168] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, SiO2 and CeO2 were used as film-forming materials to form the film in such a way that the SiO2+CeO2 film had the composition described in Table 1. Furthermore, CeO2 was used to form a CeO2 film on the substrates. Furthermore, SiO2 was used to form a SiO2 film on the substrates to produce a multilayer film. Other film-forming conditions were as described in (Production of Multilayer Film).

[0169] [Example 43]

[0170] A multilayer film was produced in the same manner as in Example 5 except that the substrate heating temperature of 350° C. in Example 5 was changed to no heating (room temperature). The temperature near the substrate during film formation was 28° C. on average.

[0171] [Example 44]

[0172] A multilayer film was produced in the same manner as in Example 16 except that the substrate heating temperature of 350° C. in Example 16 was changed to no heating (room temperature). The temperature near the substrate during film formation was 28° C. on average.

[0173] [Example 45]

[0174] A multilayer film was produced in the same manner as in Example 29 except that the substrate heating temperature of 350° C. in Example 29 was changed to no heating (room temperature). The temperature near the substrate during film formation was 29° C. on average.

[0175] [Example 46]

[0176] A multilayer film was produced in the same manner as in Example 41 except that the substrate heating temperature of 350°C in Example 41 was changed to no heating (room temperature). The temperature near the substrate during film formation was 33°C on average.

[0177] [Example 47]

[0178] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, CuO was used to form a CuO film on the substrates. Furthermore, SiO and CeO2 were used as film-forming materials on the substrates at a film-forming rate of 2.5 nm / sec. 1.5 + CeO2 film is formed in such a way that the composition is recorded in Table 1. Furthermore, CuO film is formed on it using CuO. Furthermore, SiO2 film is formed on it using SiO2 melt, thereby producing a multilayer film. Other film forming conditions are as described in (Production of multilayer film).

[0179] [Example 48]

[0180] CeO2 was used as a film-forming material to form a CeO2 film on various substrates heated to 350°C. Then, CuO was used to form a CuO film thereon. Furthermore, MgF2 melt and CaF2 melt were used as film-forming materials thereon to form the MgF2+CaF2 film in such a manner that the film had the composition described in Table 1. Other film-forming conditions were as described in (Production of Multilayer Film).

[0181] [Comparative Example 1]

[0182] An anatase TiO2 layer was formed instead of the cubic polycrystalline CeO2 layer of Example 2. At this time, Ti3O5 was used as the film-forming material, and the vacuum degree was set to 1.8×10 -2 The film was formed while introducing O2 gas in the form of Pa. A multilayer film was prepared in the same manner as in Example 2 except for this.

[0183] Here, the APC device is used to adjust the gas partial pressure in the vacuum coating device.

[0184] [Comparative Example 2]

[0185] In order to obtain anatase TiO2 layer instead of the cubic polycrystalline CeO2 layer of Example 5, the film forming material was changed to Ti3O5 material and film formation was performed while introducing O2 gas, as in Comparative Example 1. In addition, the multilayer film was prepared in the same manner as in Example 5.

[0186] [Comparative Example 3]

[0187] In order to obtain an amorphous CeO2 layer instead of the cubic polycrystalline CeO2 layer of Example 2, the substrate temperature was changed to -10°C for film formation. A multilayer film was produced in the same manner as in Example 2 except for the above.

[0188] [Comparative Example 4]

[0189] In order to obtain an amorphous CeO2 layer instead of the cubic polycrystalline CeO2 layer of Example 5, the substrate temperature was changed to -10°C for film formation. A multilayer film was produced in the same manner as in Example 5 except for this.

[0190] [Comparative Example 5]

[0191] The CeO 2 layer and the MgF 2 layer of Example 1 were formed to have a film thickness thinner than that of Example 1. A multilayer film was produced in the same manner as in Example 1 except for the above.

[0192] [Comparative Example 6]

[0193] The CeO 2 layer and the MgF 2 layer of Example 3 were formed to have a greater film thickness than that of Example 3. A multilayer film was produced in the same manner as in Example 3 except for the above.

[0194] [Comparative Example 7]

[0195] The CeO2 layer and the SiO2 layer of Example 4 were formed to have a film thickness thinner than that of Example 4. A multilayer film was produced in the same manner as in Example 4 except for the above.

[0196] [Comparative Example 8]

[0197] The CeO2 layer and the SiO2 layer of Example 6 were formed to have a greater film thickness than that of Example 6. A multilayer film was produced in the same manner as in Example 6 except for the above.

[0198] (Measurement of thickness)

[0199] The thickness of each layer of the multilayer film of Examples and Comparative Examples was measured using a spectroscopic ellipsometer (ESM300 manufactured by JA WOOLLAM Co., Ltd.). When the number of layers and film thickness were complex and difficult to analyze, the analysis was performed using the refractive index of a single layer film obtained separately in the same film formation batch.

[0200] (Determination of composition)

[0201] The composition of the layer composed of two components, such as SiO2+CeO2 and SiO2+Al2O3, in the multilayer films of the examples and comparative examples was measured and obtained using a wavelength dispersive fluorescent X-ray spectrometer (ZSX PrimusII manufactured by Rigaku Corporation).

[0202] (Determination of crystallinity)

[0203] The multilayer films of Examples and Comparative Examples were measured in the range of 2θ=20° to 100° using an XRD diffractometer (Smart Lab manufactured by Rigaku Corporation), and the layers were identified and the crystallinity was confirmed based on the intensity of the diffraction lines.

[0204] (Evaluation of hydrophilicity maintenance)

[0205] The multilayer films of the embodiments and comparative examples were placed in a dark place for 180 days, and then the contact angle with respect to water was measured. In addition, the contact angle meter used was a CA-X150 manufactured by Kyowa Interface Science Co., Ltd. 2.5 mL of pure water was dripped onto the test piece from a microsyringe, and the contact angle after dripping for 5 seconds was obtained by the θ / 2 method.

[0206] The hydrophilicity of a surface can be quantified by the contact angle with water. Generally, a contact angle of less than 20° is called hydrophilic, and a contact angle of less than 10° is called superhydrophilic. Accordingly, a contact angle of less than 10° is evaluated as [A], a contact angle of 10° or more and less than 20° is evaluated as [B], and a contact angle of 20° or more is evaluated as [C].

[0207] (Self-cleaning performance evaluation)

[0208] On the multilayer films of the embodiments and comparative examples, stearic acid was applied using a heptane solution of stearic acid (0.3% by mass) in accordance with JIS R1753-1, and dried in a dryer at 70°C for 30 minutes. Then, the contact angle of the test piece coated with stearic acid was measured in the same manner as the method described in (Evaluation of Hydrophilicity Maintenance), and it was confirmed that the contact angle was greater than 20°. Then, after irradiating with ultraviolet rays for 6 hours, the contact angle was measured again to determine the water contact angle after ultraviolet irradiation. A black light blue fluorescent lamp (FL20SBL-B manufactured by Hotalux Co., Ltd.) was used as the ultraviolet light source. The ultraviolet rays were irradiated with an illumination of 2.0 mw / cm 2 The test piece is irradiated in a manner.

[0209] Similar to the evaluation in the above (Evaluation of Hydrophilicity Maintenance), the contact angle was evaluated as [A] when it was less than 10°, the contact angle was evaluated as [B] when it was 10° or more and less than 20°, and the contact angle was evaluated as [C] when it was 20° or more.

[0210] The results obtained in (Evaluation of Hydrophilicity Maintenance) and (Evaluation of Self-Cleaning Performance) are shown in Table 1. In addition, in each of Examples and Comparative Examples, the evaluation results were the same regardless of the type of substrate.

[0211]

Table 1

[0212]

[0213] [Example 49]

[0214] The plate glass having the multilayer film obtained in Example 3 was processed and mounted on the outside of a near infrared sensor of a commercial vehicle to serve as a protective cover for the sensor.

[0215] [Example 50]

[0216] As the substrate used, a dome-shaped transparent substrate made of polymethyl methacrylate resin was used, and SiO was used as the film-forming material. A SiO2 film (200nm) was formed in the first layer. ZrO2 was used to form a ZrO2 film (15nm) in the second layer. SiO2 was used to form a SiO2 film (35nm) in the third layer. CeO2 was used to form a CeO2 film (117nm) in the fourth layer. CuO was used to form a CuO film (7nm) in the fifth layer. SiO2 and CeO2 were used to form a SiO2 (95%) + CeO2 (5%) film (80nm) in the sixth layer. SiO2 was used to form a SiO2 film (13nm) in the last seventh layer, thereby producing a multilayer film. In addition, during the film formation process, the substrate was made to planetarily rotate without heating, and the multilayer film was produced at a vapor deposition rate of 0.5nm / sec. In addition, when forming the first, fourth, fifth, and sixth layers, ion assistance was performed using an RF ion source under the condition of an O2 gas flow rate of 40sccm. At this time, the first layer was ion-assisted at an accelerating voltage of 250 V and an accelerating current of 250 mA, and the fourth, fifth, and sixth layers were ion-assisted at an accelerating voltage of 500 V and an accelerating current of 500 mA. The obtained dome-shaped resin substrate with a multilayer film was mounted on a surveillance camera in order to use it as a surveillance camera cover.

[0217] The surveillance camera with the cover was stored in a dark product vanity case for 3 months. It was then placed outdoors at night on a rainy day. Even when water was attached due to rainfall, the water droplets spread on the cover, maintaining good visibility. In addition, no water marks were left even after the water dried, maintaining good visibility. Moreover, even when it rained on a rainy day after being placed outdoors for 6 months, the water droplets still spread on the cover, maintaining good visibility.

[0218] [Example 51]

[0219] The substrate used was a resin substrate (MR-8 manufactured by Mitsui Chemicals) with a silicon-based hard coating layer formed thereon, and Al2O3 was used to form an Al2O3 film (82nm) in the first layer. CeO2 was used to form a CeO2 film (119nm) in the second layer. CuO was used to form a CuO film (7nm) in the third layer. SiO2 and CeO2 were used to form a SiO2 (95%) + CeO2 (5%) film (79nm) in the fourth layer. SiO2 was used to form a SiO2 film (15nm) in the final fifth layer, thereby producing a multilayer film. In addition, during the film formation process, the temperature of the substrate was heated to 80°C, and the multilayer film was produced at a vapor deposition rate of 0.5nm / sec. The obtained resin substrate with a multilayer film was processed and mounted on a frame for glasses to produce glasses. The produced glasses were stored in a glasses case in a dark place for 3 months. Then, when water droplets adhered to the lens, the water droplets wetted and spread on the lens, maintaining good visibility. The contact angle of water at this time was 5°. In addition, even after the water dried, no water marks remained, maintaining good visibility.

[0220] Industrial Applicability

[0221] The multilayer film disclosed herein can be used in optical components such as filters, optical lenses, lighting lenses, optical films, optical prisms, eyeglass lenses, lenses for photographing, rearview mirrors for vehicles, flat glass, focusing lenses, cover glasses for display screens, touch panels, and various films, covers for protecting optical components such as covers for surveillance cameras, covers for vehicle-mounted cameras, covers for vehicle-mounted sensors, etc.

[0222] In addition, the optical components disclosed herein can be used as optical instruments such as digital cameras, digital video cameras, sports cameras, endoscopes, lens barrels, glasses, sensors, binoculars, telescopes, surveillance cameras, vehicle-mounted cameras, smart phones, tablet computers (Tablet PCs), weather cameras, live cameras, protective goggles, swimming goggles, head-mounted displays, sunglasses, smart glass, masks, helmet shields, vehicle reflectors, and bathroom reflectors, as well as covers to protect them.

[0223] The present disclosure includes the following embodiments. (1)

[0225] A multilayer film, characterized by comprising: a layer containing cerium oxide; and

[0226] A layer containing silicon oxide or a layer containing magnesium fluoride is formed directly on the layer containing cerium oxide or via another layer.

[0227] The layer containing cerium oxide contains cerium oxide having a cubic polycrystalline structure.

[0228] The film thickness of the layer containing the cerium oxide is 70 nm to 300 nm,

[0229] The thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is not less than 50 nm and not more than 240 nm,

[0230] The layer containing silicon oxide and the layer containing magnesium fluoride have a refractive index of 1.65 or less at a wavelength of 500 nm. (2)

[0232] The multilayer film according to (1), wherein the composition of cerium oxide contained in the layer containing cerium oxide is CeO x (x=1.5 or more and 2.0 or less). (3)

[0234] The multilayer film according to (1) or (2), wherein the content ratio of cerium oxide in the layer containing cerium oxide is 85 mass % or more relative to the entire layer containing cerium oxide. (4)

[0236] The multilayer film according to any one of (1) to (3), wherein the content ratio of silicon oxide in the layer containing silicon oxide is 65 mass % or more relative to the entire layer containing silicon oxide. (5)

[0238] The multilayer film according to (4), characterized in that

[0239] The layer containing silicon oxide contains aluminum oxide,

[0240] The content ratio of aluminum oxide in the layer containing silicon oxide is 0.1 mass % or more and 10 mass % or less relative to the entire layer containing silicon oxide. (6)

[0242] The multilayer film according to (4), characterized in that

[0243] The layer containing silicon oxide contains cerium oxide,

[0244] The content ratio of cerium oxide in the layer containing silicon oxide is 0.1 mass % or more and 35 mass % or less. (7)

[0246] The multilayer film according to any one of (1) to (6), characterized in that

[0247] A layer containing silicon dioxide is provided directly on the layer containing silicon oxide or the layer containing magnesium fluoride or via another layer,

[0248] The film thickness of the layer containing silicon dioxide is 30 nm or less. (8)

[0250] The multilayer film according to any one of (1) to (7), characterized in that

[0251] A layer composed of a first metal oxide is provided between the layer containing cerium oxide and the layer containing silicon oxide or the layer containing magnesium fluoride,

[0252] The layer composed of the first metal oxide contains a metal oxide composed of a polycrystalline structure,

[0253] The film thickness of the layer composed of the first metal oxide is not less than 0.5 nm and not more than 15 nm. (9)

[0255] The multilayer film according to (8), characterized in that

[0256] The metal oxide is composed of CuO x The copper oxide represented by , wherein x=0.5 or more and 1.0 or less. (10)

[0258] The multilayer film according to (8), characterized in that

[0259] The metal oxide is composed of CeO x The cerium oxide represented by ? is composed of a cubic polycrystalline structure, wherein x=1.5 to 2.0. (11)

[0261] The multilayer film according to (7), characterized in that

[0262] A layer composed of a second metal oxide is provided between the layer containing silicon oxide or the layer containing magnesium fluoride and the layer containing silicon dioxide,

[0263] The layer composed of the second metal oxide contains a metal oxide composed of a polycrystalline structure,

[0264] The film thickness of the layer composed of the second metal oxide is not less than 0.5 nm and not more than 7 nm. (12)

[0266] The multilayer film according to (11), characterized in that

[0267] The metal oxide is composed of CuO x The copper oxide represented by , wherein x=0.5 or more and 1.0 or less. (13)

[0269] The multilayer film according to (11), characterized in that

[0270] The metal oxide is composed of CeO x The cerium oxide represented by ? is composed of a cubic polycrystalline structure, wherein x=1.5 to 2.0. (14)

[0272] An optical component comprising the multilayer film according to any one of (1) to (13). (15)

[0274] A method for manufacturing a multilayer film, characterized by comprising:

[0275] forming a layer containing cerium oxide on a substrate directly or via other layers by a vacuum deposition method; and

[0276] forming a layer containing silicon oxide or a layer containing magnesium fluoride directly on the layer containing cerium oxide or via another layer by a vacuum deposition method,

[0277] The layer containing cerium oxide contains cerium oxide having a cubic polycrystalline structure.

[0278] The film thickness of the layer containing the cerium oxide is 70 nm to 300 nm,

[0279] The thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is not less than 50 nm and not more than 240 nm,

[0280] The layer containing silicon oxide and the layer containing magnesium fluoride have a refractive index of 1.65 or less at a wavelength of 500 nm.

[0281] This application claims priority based on Japanese patent application No. 2022-144038 filed on September 9, 2022, the entire contents of which are incorporated herein by reference.

[0282] Description of symbols

[0283] 11. Substrate

[0284] 12 Other layers

[0285] 13 Layer containing cerium oxide

[0286] 14 Layer containing magnesium fluoride

[0287] 15 Layer containing silicon oxide

[0288] 16 Layer containing silicon dioxide

[0289] 17 Layer consisting of a first metal oxide

[0290] 18 Layer consisting of a second metal oxide

[0291] 21 Dome-shaped resin substrate

[0292] 31. Eyeglass lenses

[0293] 32 Eyeglass frames.

Claims

1. A multilayer film, characterized in that: have: a layer comprising cerium oxide; and A layer containing silicon oxide or a layer containing magnesium fluoride is formed directly on the layer containing cerium oxide or via another layer. The layer containing cerium oxide contains cerium oxide having a cubic polycrystalline structure. The film thickness of the layer containing the cerium oxide is 70 nm to 300 nm, The thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is not less than 50 nm and not more than 240 nm, The layer containing silicon oxide and the layer containing magnesium fluoride have a refractive index of 1.65 or less at a wavelength of 500 nm.

2. The multilayer film according to claim 1, characterized in that The composition of cerium oxide contained in the cerium oxide-containing layer is CeO x , where x=1.5 or more and 2.0 or less.

3. The multilayer film according to claim 1, characterized in that The content ratio of cerium oxide in the layer containing cerium oxide is 85 mass % or more based on the entire layer containing cerium oxide.

4. The multilayer film according to claim 1, characterized in that The content ratio of silicon oxide in the layer containing silicon oxide is 65 mass % or more based on the entire layer containing silicon oxide.

5. The multilayer film according to claim 4, characterized in that The layer containing silicon oxide contains aluminum oxide, The content ratio of aluminum oxide in the layer containing silicon oxide is 0.1 mass % or more and 10 mass % or less relative to the entire layer containing silicon oxide.

6. The multilayer film according to claim 4, characterized in that The layer containing silicon oxide contains cerium oxide, The content ratio of cerium oxide in the layer containing silicon oxide is 0.1 mass % or more and 35 mass % or less.

7. The multilayer film according to claim 1, characterized in that A layer containing silicon dioxide is provided directly on the layer containing silicon oxide or the layer containing magnesium fluoride or via another layer, The film thickness of the layer containing silicon dioxide is 30 nm or less.

8. The multilayer film according to claim 1, characterized in that A layer composed of a first metal oxide is provided between the layer containing cerium oxide and the layer containing silicon oxide or the layer containing magnesium fluoride, The layer composed of the first metal oxide contains a metal oxide composed of a polycrystalline structure, The film thickness of the layer composed of the first metal oxide is not less than 0.5 nm and not more than 15 nm.

9. The multilayer film according to claim 8, characterized in that The metal oxide is composed of CuO x The copper oxide represented by , wherein x=0.5 or more and 1.0 or less.

10. The multilayer film according to claim 8, characterized in that The metal oxide is composed of CeO x The cerium oxide represented by ? is composed of a cubic polycrystalline structure, wherein x=1.5 to 2.

0.

11. The multilayer film according to claim 7, characterized in that A layer composed of a second metal oxide is provided between the layer containing silicon oxide or the layer containing magnesium fluoride and the layer containing silicon dioxide, The layer composed of the second metal oxide contains a metal oxide composed of a polycrystalline structure, The film thickness of the layer composed of the second metal oxide is not less than 0.5 nm and not more than 7 nm.

12. The multilayer film according to claim 11, characterized in that The metal oxide is composed of CuO x The copper oxide represented by , wherein x=0.5 or more and 1.0 or less.

13. The multilayer film according to claim 11, characterized in that The metal oxide is composed of CeO x The cerium oxide represented by ? is composed of a cubic polycrystalline structure, wherein x=1.5 to 2.

0.

14. An optical component, characterized in that: A multilayer film according to any one of claims 1 to 13.

15. A method for manufacturing a multilayer film, characterized in that: include: forming a layer containing cerium oxide on a substrate directly or via other layers by a vacuum coating method; as well as forming a layer containing silicon oxide or a layer containing magnesium fluoride directly on the layer containing cerium oxide or via another layer by a vacuum deposition method, The layer containing cerium oxide contains cerium oxide having a cubic polycrystalline structure. The film thickness of the layer containing the cerium oxide is 70 nm to 300 nm, The thickness of the layer containing silicon oxide and the layer containing magnesium fluoride is not less than 50 nm and not more than 240 nm, The layer containing silicon oxide and the layer containing magnesium fluoride have a refractive index of 1.65 or less at a wavelength of 500 nm.

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