WO2024053124A1

WO2024053124A1 - Multilayer film, optical component, spectacles and method for producing multilayer film

Info

Publication number: WO2024053124A1
Application number: PCT/JP2022/046336
Authority: WO
Inventors: 学小長井; 哲也村田; 盛忠戸松
Original assignee: キヤノンオプトロン株式会社
Priority date: 2022-09-09
Filing date: 2022-12-16
Publication date: 2024-03-14

Abstract

The present invention addresses the problem of providing a multilayer film having excellent antifogging properties and excellent antifogging retention properties by forming a low refractive index layer having a certain film thickness above a layer having a photocatalytic function. In order to solve this problem, the following multilayer film is provided. Namely, the multilayer film is characterized in that the multilayer film has, directly on the surface of or via another layer on a substrate, a layer having a film thickness of 70-300 nm inclusive and containing cerium oxide having a cubic polycrystalline structure, has, above the layer containing cerium oxide, a layer having a film thickness of 50-240 nm inclusive and a refractive index at a wavelength of 500 nm of 1.46-1.65 inclusive and containing silicon oxide, and has, above the layer containing silicon oxide, a layer having a film thickness of 2-10 nm inclusive and a refractive index at a wavelength of 500 nm of 1.33-1.45 inclusive and containing porous silica.

Description

Multilayer film, optical member, glasses, and method for producing multilayer film

The present disclosure relates to a multilayer film with excellent antifogging properties and antifogging maintenance performance, an optical member having the multilayer film, eyeglasses having the optical member, and a method for manufacturing the multilayer film.

Optical members such as optical lenses, mirrors, and optical filters have films formed of inorganic materials in order to increase or decrease light transmittance or reflectance. However, when moisture such as steam or exhaled air adheres to the surface of the optical member, it becomes minute droplets and covers the surface, causing a problem that the optical member becomes cloudy.
Several anti-fogging technologies have been proposed, but one known technology is to coat the surface of an optical member with a hydrophilic substance such as a silanol group (Si-OH) to spread water droplets uniformly to prevent fogging. (Patent Document 1). However, although such a hydrophilic surface has good antifogging performance, the surface free energy decreases in a relatively short period of time due to the adhesion of environmentally derived dirt. Therefore, there was a problem that the hydrophilic performance deteriorated and the antifogging performance could not be maintained.

As a means to solve the above-mentioned problems, a hydrophilic film in which a silicon dioxide thin film is formed on a crystalline titanium dioxide thin film is used (Patent Document 2, Patent Document 3, Non-Patent Document 1). When the surface of crystalline titanium dioxide is irradiated with near-ultraviolet light, active oxygen is generated by the photocatalytic function, and the generated active oxygen decomposes organic matter on the surface of the hydrophilic film. As a result, the hydrophilic properties of the hydrophilic membrane are restored, dirt is washed away by rainfall, and the membrane is self-purified.

Patent No. 3435136 Japanese Patent Application Publication No. 09-057912 Japanese Patent Application Publication No. 2000-053449

However, when a silicon dioxide thin film is formed on a titanium dioxide thin film, since the refractive index of titanium dioxide is large, the reflectance increases if the thickness of the low refractive index layer such as silicon dioxide on the surface is less than 50 nm. However, there was a problem that the transmittance decreased. Therefore, although it can be applied to car-mounted door mirrors where there is no problem even if the reflectance increases, there is a problem that it is not suitable for optical members such as lenses equipped with an anti-reflection film.

On the other hand, when the thickness of the low refractive index layer such as silicon dioxide on the surface is 50 nm or more, although it is suitable in terms of reducing reflectance, the hydrophilicity recovery function due to the photocatalytic function is insufficient, and it is difficult to prevent. There was a problem that fogging performance could not be maintained. In addition, silicon dioxide thin films have insufficient antifogging performance, and a thin film with even better antifogging performance has been desired.

The object of the present disclosure is to provide a multilayer film with excellent antifogging properties and excellent antifogging maintenance performance by forming a low refractive index layer having a specific thickness on top of a layer having a photocatalytic function.

The multilayer film of the present disclosure can be applied to the surface of the base material directly or through another layer.
a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure;
A layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer containing porous silica having a thickness of 2 nm or more and 10 nm or less and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm is provided on the upper layer side of the layer containing silicon oxide. do.
The method for producing a multilayer film of the present disclosure includes applying the method to the surface of the base material directly or through another layer.
forming a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure;
forming a layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer of alkoxysilane is formed on the upper layer side of the layer containing silicon oxide, and is hydrolyzed to form a porous film having a thickness of 2 nm or more and 10 nm or less, and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm. forming a layer containing silica.
Moreover, according to another aspect of the present disclosure, an optical member having the above multilayer film is provided.
Furthermore, according to another aspect of the present disclosure, there is provided eyeglasses having the optical member described above.

According to one aspect of the present disclosure, there is provided a multilayer film with excellent antifogging properties and antifogging maintenance performance when a low refractive index layer having a specific thickness is formed above a layer having a photocatalytic function, and the above multilayer film. An optical member having the above and a method for manufacturing the multilayer film described above can be obtained.

1 is a schematic cross-sectional view showing the configuration of a first embodiment of a multilayer film according to the present disclosure. FIG. 1 is a schematic diagram showing an embodiment (glasses) of an optical member according to the present disclosure.

Hereinafter, embodiments of a multilayer film, an optical member having the multilayer film, and a method for forming the multilayer film according to the present disclosure will be described by citing preferred embodiments.
Further, the present disclosure is not limited to the embodiments below.
In addition, in the present disclosure, the descriptions of [XX to YY] and [XX to YY] representing a numerical range mean a numerical range including the lower limit and upper limit, which are the end points, unless otherwise specified. Furthermore, when numerical ranges are described in stages, the upper and lower limits of each numerical range can be combined arbitrarily.

In the present disclosure, a multilayer film refers to a structure including two or more layers formed on a surface of a base material. The multilayer film does not include a base material.
In the present disclosure, the base material is a solid article.
In the present disclosure, the optical member is an optical member including a base material having the multilayer film described above. The optical components include optical filters, optical lenses, daylighting lenses, optical films, optical prisms, eyeglass lenses, photographic lenses, surveillance camera covers, vehicle camera covers, vehicle sensor covers, vehicle door mirrors, plate glass, and condensing light. Examples include lenses, display cover glasses, touch panels, and various films.

The multilayer film of the present disclosure has a cerium oxide-containing layer having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure directly or through another layer on the surface of a base material. A layer containing silicon oxide has a film thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing silicon oxide, and the upper layer of the layer containing silicon oxide. It is characterized by having a layer containing porous silica having a thickness of 2 nm or more and 10 nm or less and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm.

Before specifically explaining the multilayer film according to the present disclosure, in order to understand the present disclosure, first, the estimation of the mechanism that produces the effect will be described below. However, the following explanation is merely a hypothesis, and the present disclosure is not limited by the following hypothesis in any way.
The present inventor has discovered that when a layer containing silicon oxide with a specific thickness and a layer containing porous silica on the upper layer side are arranged on the surface, the lower layer side in contact with the layer has a cubic polycrystalline structure. It has been found that by arranging a layer containing cerium oxide, self-cleaning properties and anti-fogging maintenance performance by photocatalyst are exhibited. Regarding the above mechanism, the following contents can be considered.

When a photocatalytic film that responds to near-ultraviolet light is irradiated with near-ultraviolet light, holes and electrons are generated due to photoexcitation. When the generated holes and electrons can reach the surface of the membrane, a chemical reaction occurs, and self-purification and hydrophilicity recovery functions are developed. However, when a low refractive index layer with a specific thickness of 50 nm or more is formed on the top layer of crystalline titanium dioxide, holes and electrons generated by photoexcitation are blocked by the thickness and reach the multilayer film surface. Can not. Therefore, the holes and electrons are recombined and deactivated, and self-cleaning properties and anti-fog maintenance performance are not exhibited. On the other hand, when a low refractive index layer with a thickness of 50 nm or more is formed on the layer containing cerium oxide of the present disclosure, the proportion of holes and electrons that reach the multilayer film surface increases, causing a chemical reaction. Demonstrates self-purification and anti-fog maintenance performance. At the interface of the upper layer in contact with the cerium oxide-containing layer of the present disclosure, there is a region where the compounds and mixtures of the respective layers are interdiffused. Trivalent and tetravalent cerium tend to coexist in this region, making it easier to hold electrons generated by photoexcitation, which may make it difficult for holes and electrons to recombine. Furthermore, since it has a cubic polycrystalline structure, it has high conductivity and has many interfaces, which may make it easier for holes and electrons to move, making it difficult for them to recombine.
In addition, the present inventors discovered that in a case where a layer containing silicon oxide and a layer containing porous silica are disposed above the layer, the layer containing silicon oxide has a cubic polycrystalline structure on the lower layer side. It has been found that anti-fogging performance can be dramatically improved by arranging a layer containing cerium oxide. Regarding the above mechanism, the following contents can be considered.

The layer containing porous silica of the present disclosure has a large surface area due to its porosity, and has more silanol groups (Si-OH), which is a hydrophilic substance, than non-porous silicon oxide, so it has excellent antifogging performance. may be superior to In addition, when a layer containing cubic polycrystalline cerium oxide is exposed to ultraviolet light or higher energy rays, electrical, chemical, and other energy is stored within the cerium oxide and at its interface. It is thought 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 in a high state and improving the antifogging maintenance performance. In particular, in the layer containing cerium oxide of the present disclosure formed by vacuum evaporation, trivalent and tetravalent cerium tend to coexist, so it may be in a state where energy is easily stored.

<<First embodiment>>
FIG. 1 is a schematic cross-sectional view showing a first embodiment of the multilayer film of the present disclosure provided on a base material, in which another layer 12 is formed on the base material 11, and A configuration example is shown in which a layer 13 containing cerium oxide is formed, a layer 14 containing silicon oxide of the present disclosure is additionally formed, and a layer 15 containing porous silica of the present disclosure is further formed. Note that FIG. 1 schematically represents the configuration of a multilayer film in the present disclosure. Therefore, the area and film thickness of each layer are not expressed in accurate ratios. Further, the other layer 12 may or may not be present.

The base material 11 will be explained.
The base material 11 may be any material as long as it is capable of laminating the other layer 12 or the layer 13 containing cerium oxide according to the present disclosure, and may be made of glass, ceramics, resin, or metal. The shape of the base material is not limited and may be flat, curved, concave, convex, or film-like. Moreover, it may have a hard coat layer or a barrier layer. In addition, the size and thickness are not particularly limited, and can be set as appropriate depending on the intended use.

The layer 13 containing cerium oxide according to the present disclosure will be explained. The multilayer film of the present disclosure has a layer 13 containing cerium oxide on the upper layer side of the base material 11. The cerium oxide-containing layer 13 of the present disclosure is a cerium oxide-containing layer having a cubic polycrystalline structure. In a layer made of cerium oxide with a polycrystalline structure, cracks are less likely to occur in the multilayer film. Further, when the layer containing cerium oxide has a cubic polycrystalline structure, the self-purification function by photocatalyst and the anti-fog maintenance performance are high.
Note that the definition of polycrystalline structure in the present disclosure includes the appearance of a peak unique to cerium oxide in X-ray diffraction (XRD) measurement of a thin film after film formation.

The layer 13 containing cerium oxide of the present disclosure has a thickness of 70 nm or more and 300 nm or less. When the film thickness is 70 nm or more, the photocatalytic self-purification function and anti-fog maintenance performance are high. When the film thickness is 300 nm or less, cracks do not occur, and non-uniformity and surface roughness do not become too large, which can have a positive effect on optical properties.
The composition of cerium oxide in the cerium oxide-containing layer 13 of the present disclosure is CeO _x , and x is preferably 1.5 or more and 2.0 or less. Within the above range, a more transparent thin film can be obtained in the wavelength range from visible light to near infrared rays.
The content ratio of cerium oxide in the total amount of substances constituting the layer 13 containing cerium oxide of the present disclosure is preferably 85% by mass or more. If the content ratio of cerium oxide is 85% by mass or more, the anti-fog maintenance performance will be further improved.
The layer 13 containing cerium oxide of the present disclosure may be placed directly on the base material 11 or may be placed via another layer 12.

As other layers 12, layers containing metals, fluorides, oxides, carbides, and nitrides can be arranged. Specifically, the other layers 12 include aluminum (Al), chromium (Cr), gold (Au), silver (Ag), copper (Cu), silicon (Si), germanium (Ge), and titanium (Ti). ), metal layers containing elements such as nickel (Ni), layers containing fluorides such as magnesium fluoride (MgF ₂ ) and calcium fluoride (CaF ₂ ), silicon oxide (SiO _x ), and aluminum oxide. (Al ₂ O _x ), yttrium oxide (Y ₂ O _x ), zirconium oxide (ZrO _x ), hafnium oxide (HfO _x ), zinc oxide (ZnO _x ), tantalum oxide (Ta ₂ O _x ), niobium oxide (Nb _2Ox ₎ , indium oxide ( _In2Ox ), tin oxide ( _SnOx ), tungsten oxide ( _WOx ), cerium oxide ( _CeOx ), titanium oxide ( _TiOx ₎ , lanthanum titanate ( _LaxTiy ₎ O _z ), aluminum titanate (La _x Al _y O _z ), layers containing oxides such as alumina-doped silicon dioxide (SiO ₂ +Al ₂ O ₃ ), nitrides such as silicon nitride (Si ₃ N ₄ ) A layer containing carbide such as tungsten carbide (WC), etc. can be used. The other layer 12 may be one layer, or when it is a multilayer of two or more layers, the other layer 12 may be configured by combining a plurality of types of layers among the layers exemplified above. Further, the other layer 12 may be a layer containing a mixture of two or more of the compounds contained in the layers exemplified above.

The method of forming the other layer 12 is not particularly limited. Other methods for forming the layer 12 include, for example, dry film forming methods such as sputtering, vacuum evaporation, and ion plating, dipping, coating, spraying, spin coating, bar coating, etc. It is possible to apply a wet film forming method such as a printing method or a flow coating method.
By adjusting the composition, refractive index, film thickness, number of layers, etc. of the other layers 12 according to the purpose and function, antireflection layer, half mirror layer, light absorption layer, alkali diffusion prevention layer, adhesion layer, antistatic layer, etc. It can be made into a multilayer film with specific functions added, such as a heater layer.

The layer 14 containing silicon oxide according to the present disclosure will be explained. The multilayer film of the present disclosure has a layer 14 containing silicon oxide on the upper layer side of a layer 13 containing cerium oxide. The thickness of the layer 14 containing silicon oxide is 50 nm or more and 240 nm or less. When the thickness is 50 nm or more, the reflectance of the multilayer film does not become too high. On the other hand, when the thickness is 240 nm or less, the self-purifying function of the photocatalyst is exhibited on the surface of the multilayer film.
The refractive index of the layer 14 containing silicon oxide is 1.46 or more and 1.65 or less at a light wavelength of 500 nm. If it exceeds 1.65, the reflectance of the multilayer film may become too high. On the other hand, when it is less than 1.46, the anti-fog maintenance performance decreases.
The content of silicon oxide in the layer 14 containing silicon oxide is preferably 65% by mass or more based on the entire layer 14 containing silicon oxide. If the content rate of silicon oxide in the layer 14 containing silicon oxide is within the above range, the anti-fog maintenance performance will be further enhanced.

In the layer 14 containing silicon oxide, the composition of silicon oxide is SiO _x , and x is preferably 1.5 or more and 2.0 or less. If the value of x in the silicon oxide composition SiO _x is within the above range, the refractive index of the layer 14 containing silicon oxide can be 1.65 or less. Further, a more transparent film can be obtained in the wavelength range from visible light to near infrared rays.

The layer 15 containing porous silica according to the present disclosure will be explained. The multilayer film of the present disclosure has a layer 15 containing porous silica on the upper layer side of a layer 14 containing silicon oxide. The thickness of the layer 15 containing porous silica is 2 nm or more and 10 nm or less. When the film thickness is 2 nm or more and 10 nm or less, the antifogging performance of the multilayer film can be improved. The layer 15 containing porous silica has a refractive index of 1.33 or more and 1.45 or less at a light wavelength of 500 nm. When the refractive index is 1.33 or more and 1.45 or less, the antifogging performance of the multilayer film can be improved. When the refractive index exceeds 1.45, pores decrease and antifogging performance deteriorates. On the other hand, when the refractive index is less than 1.33, the number of pores increases and the strength of the layer containing porous silica decreases.
The layer containing porous silica is preferably formed by a hydrolysis reaction of alkoxysilane. Alkoxysilane is represented by the general formula H _2n+1 C _n O(Si(OC _n H _2n+1 ) ₂ O) _m C _n H _2n+1 . n is preferably 1 or more and 4 or less, and m is preferably 1 or more and 100 or less. m is more preferably 4 or more and 50 or less, further preferably 6 or more and 10 or less. Specific examples include methyl polysilicate (Methyl Silicate 53A manufactured by Colcoat), ethyl polysilicate (Ethyl Silicate 48 manufactured by Colcoat), propyl polysilicate, and butyl polysilicate.

≪Optical members≫
FIG. 2 is a schematic diagram showing a configuration in an embodiment using the optical member of the present disclosure. FIG. 2 shows eyeglasses, which are composed of eyeglass lenses 21 and eyeglass frames 22, which are optical members according to the present disclosure. A multilayer film according to the present disclosure is formed on both sides of the spectacle lens 21.
The multilayer film of the present disclosure can be used for optical thin films such as antireflection films, various optical filter multilayer films, and optical mirror multilayer films. Further, it can be used for optical members such as optical lenses, daylight lenses, optical films, optical prisms, camera sensors and infrared sensors, and covers for protecting the optical members. In addition, by coating the back side of the base material 11 with a composition, refractive index, film thickness, number of layers, etc. according to the purpose and function, it is possible to create a mirror layer, half mirror layer, light absorption layer, transparent heater layer, reflective layer, etc. It can be an optical member with a specific function added, such as a prevention layer.

≪Multilayer film manufacturing method≫
Further, the method for manufacturing a multilayer film of the present disclosure is characterized in that it is formed by a method including at least the following steps (A), (B), and (C).
(A) A step of forming a layer 13 containing cerium oxide on the surface of the base material directly or via another layer by vacuum evaporation.
(B) A step of forming a layer 14 containing silicon oxide on the layer 13 containing cerium oxide of the present disclosure described above by a vacuum evaporation method.
(C) A step of forming an alkoxysilane layer on the upper layer side of the layer 14 containing silicon oxide by a vacuum evaporation method and hydrolyzing it to form a layer 15 containing porous silica.

The layer 13 containing cerium oxide formed in the above step (A) contains cerium oxide having a cubic polycrystalline structure, and the layer 13 containing cerium oxide formed in the above step (A) The thickness is 70 nm or more and 300 nm or less. The film thickness of the layer 14 containing silicon oxide formed in the above step (B) is 50 nm or more and 240 nm or less, and the refraction of the layer 14 containing silicon oxide formed in the above step (B) at a wavelength of light of 500 nm. The ratio is 1.46 or more and 1.65 or less. Further, the thickness of the layer 15 containing porous silica formed in the above step (C) is 2 nm or more and 10 nm or less, and the layer 15 containing porous silica formed in the above step (C) is resistant to light. The refractive index at a wavelength of 500 nm is 1.33 or more and 1.45 or less. At this time, high antifogging properties and high antifogging maintenance performance are obtained.

The substrate temperature during vacuum deposition is preferably a temperature at which the layer containing cerium oxide crystallizes. Although it depends on the allowable temperature limit of the base material used and other film forming conditions, the temperature can usually be selected within the range of 0° C. or higher and 500° C. or lower.
The method of evaporating the thin film forming material in vacuum evaporation is not limited as long as the thin film forming material is evaporated. For example, as the evaporation method, an evaporation means such as an electron gun, resistance heating, or laser can be applied. Further, as the evaporation means, ion assist, plasma assist, etc. can be used in combination as necessary.

The multilayer film of the present disclosure can be suitably manufactured by the above method.

Hereinafter, the present disclosure will be described in further detail using examples, but the present disclosure is not limited to the following examples in any way.

(Base material)
The flat base materials listed below were used.
・Made of borosilicate glass, thickness 3mm
・Made of synthetic quartz, thickness 3mm
・Made of polycarbonate resin, thickness 2mm
・Made of polymethyl methacrylate resin, thickness 2mm

(Thin film forming material)
The materials listed below were used.
・CeO ₂ cylindrical purity 99.9%
・Sm ₂ O ₃ granules Purity 99.9%
・SiO ₂ grains purity 99.9%
・_Al2O ₃ grains purity 99.9%
・Ti ₃ O ₅ granules Purity 99.9%
・_O2 gas purity 99.999%
・Methyl silicate 53A liquid purity 97.0%
・Ethyl silicate 48 liquid purity 94.0%
Note that methyl silicate 53A and ethyl silicate 48 are product names of Colcoat Co., Ltd.

(Preparation of multilayer film)
Common film forming methods and film forming conditions for Examples and Comparative Examples in producing a multilayer film will be explained. A vacuum evaporation apparatus (dome diameter Φ900 mm, evaporation distance 890 mm) was used as a film forming apparatus. The above-mentioned thin film forming material and various clean base materials were set in an apparatus, and the apparatus was evacuated to a degree of vacuum (7.0×10 ⁻⁴ Pa) at which film formation was started. The substrate temperature during film formation is -10°C or more and 60°C or less. Thereafter, a multilayer film was formed on the set base material by a vacuum evaporation method using a thin film forming material as listed in Table 1 to obtain a test piece. At that time, each layer was deposited at a deposition rate of about 0.5 nm/sec. Thin films made of two components, such as CeO ₂ + Al ₂ O ₃ and SiO ₂ + Al ₂ O ₃ , can be produced using a binary method, which is a method in which two types of thin film forming materials are placed in each of two heating sources and evaporated simultaneously. The film was formed by a vapor deposition method.
The film-formed base material was immersed in 50 ml of hydrochloric acid with a concentration of 0.01 mol/l for 16 hours to promote the hydrolysis reaction of the alkoxysilane, and a layer containing porous silica was formed from the alkoxysilane layer.
In addition, in each of Examples 1 to 7 and Comparative Examples 1 to 4, the multilayer films obtained by changing the type of base material were not substantially different from each other except for the type of base material. Only examples are listed. Moreover, "polycrystal" in Table 1 means a cubic polycrystalline structure.

Hereinafter, individual conditions for each example and comparative example in multilayer film production will be described.
[Examples 1 to 3]
A CeO ₂ thin film (a layer containing cerium oxide) was formed on various base materials using a CeO ₂ sintered body as a thin film forming material. Subsequently, a SiO ₂ thin film (a layer containing silicon oxide) was formed thereon using a SiO ₂ melt as a thin film forming material. Subsequently, a layer containing porous silica was formed thereon using methyl silicate 53A as a thin film forming material to produce a multilayer film. Other film forming conditions are as described in (Preparation of multilayer film).

[Example 4]
CeO _1.8 thin films were formed on various substrates using a CeO ₂ sintered body and metal cerium as thin film forming materials. Subsequently, a SiO ₂ thin film was formed thereon using a SiO ₂ melt as a thin film forming material. Subsequently, a layer containing porous silica was formed thereon using methyl silicate 53A as a thin film forming material to produce a multilayer film. Other film forming conditions are as described in (Preparation of multilayer film).

[Example 5]
CeO _1.8 (85%) + Al ₂ O ₃ (15%) thin films were formed on various substrates using two of CeO ₂ sintered body and Al ₂ O ₃ melt as thin film forming materials. Subsequently, a SiO ₂ thin film was formed thereon using a SiO ₂ melt as a thin film forming material. Subsequently, a layer containing porous silica was formed thereon using methyl silicate 53A as a thin film forming material to produce a multilayer film. Other film forming conditions are as described in (Preparation of multilayer film).

[Example 6]
CeO _1.8 (85%) + Sm ₂ O ₃ (15%) thin films were formed on various substrates using two sintered bodies, CeO ₂ sintered body and Sm ₂ O ₃ sintered body, as thin film forming materials. . Subsequently, a SiO ₂ thin film was formed thereon using a SiO ₂ melt as a thin film forming material. Subsequently, a layer containing porous silica was formed thereon using methyl silicate 53A as a thin film forming material to produce a multilayer film. Other film forming conditions are as described in (Preparation of multilayer film).

[Example 7]
CeO ₂ polycrystalline thin films were formed on various substrates using a CeO ₂ sintered body as a thin film forming material. Subsequently, a SiO ₂ (65%)+CeO ₂ (35%) thin film was formed thereon using two materials, a SiO ₂ melt and a CeO ₂ sintered body, as thin film forming materials. Subsequently, a layer containing porous silica was formed thereon using methyl silicate 53A as a thin film forming material to produce a multilayer film. Other film forming conditions are as described in (Preparation of multilayer film).

[Comparative example 1]
In order to obtain an anatase type TiO ₂ layer instead of the cubic polycrystalline CeO ₂ layer in Example 2, the thin film forming material was changed to a Ti ₃ O ₅ material, and the film was formed while introducing O ₂ gas. did. A multilayer film was produced in the same manner as in Example 2 except for this.

[Comparative example 2]
In order to obtain an amorphous CeO ₂ layer instead of the cubic polycrystalline CeO ₂ layer of Example 2, the substrate temperature was changed to -10° C. to form a film. A multilayer film was produced in the same manner as in Example 2 except for this.

[Comparative example 3]
The CeO ₂ layer and the SiO ₂ layer were formed to have a thinner film thickness than in Example 1. A multilayer film was produced in the same manner as in Example 1 except for this.

[Comparative example 4]
The CeO ₂ layer and the SiO ₂ layer were formed to be thicker than in Example 3. A multilayer film was produced in the same manner as in Example 3 except for this.

(Measurement of thickness)
The thickness of each layer of the multilayer films of Examples and Comparative Examples was measured using spectroscopic ellipsometry (ESM300, manufactured by JA WOOLLAM). If the number of layers and film thickness were complicated and analysis was difficult, analysis was performed using the refractive index of a single-layer film separately obtained from the same batch of film formation.

(Measurement of composition)
The composition of the layer consisting of two components such as SiO ₂ +CeO ₂ and SiO ₂ +Al ₂ O ₃ in the multilayer films of Examples and Comparative Examples was measured using a wavelength dispersive X-ray fluorescence spectrometer (ZSX Primus II manufactured by Rigaku Corporation). I asked.

(Measurement of crystallinity)
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 Co., Ltd.), and layer identification and crystallinity were confirmed by diffraction line intensity, etc. went.

(Evaluation of anti-fog properties and anti-fog maintenance performance)
On the day the multilayer film was produced, the haze difference was measured according to the following method. Then, the produced multilayer film was placed in an airtight container with the film surface facing up, and the lid was closed. The airtight container was left in the laboratory with the lid closed. After 180 days had passed, the lid was opened, the multilayer film was taken out, and the haze difference was measured according to the method below.
A CM-5 spectrophotometer manufactured by Konica Minolta, Inc. was used as a haze difference measuring device. Steam at about 100° C. was sprayed onto the multilayer film using a humidifier, and the haze difference was measured after 3 seconds. The antifogging performance was evaluated in four stages based on the measured haze difference. Here, the haze difference is defined as (the haze value 3 seconds after spraying steam at about 100°C onto the multilayer film using a humidifier) to (when using a humidifier for a base material without a multilayer film). This is the value obtained by subtracting the haze value when no steam is sprayed.
A: Haze difference less than 1 B: Haze difference 1 or more and less than 15 C: Haze difference 15 or more and less than 35 D: Haze difference 35 or more The results are shown in Table 1 below.

[Example 8]
The base material used is a resin substrate (Mitsui Chemicals MR-8) on which a silicone hard coat is formed, and the first layer is an Al ₂ O ₃ film (film thickness 82 nm) using an Al ₂ O ₃ melt. was formed. A CeO ₂ film (thickness: 119 nm) was formed as the second layer using a CeO ₂ sintered body. A SiO ₂ (95%)+CeO ₂ (5%) film (film thickness: 79 nm) was formed as the third layer using a SiO ₂ melt and a CeO ₂ sintered body. In the fourth and final layer, an alkoxysilane layer is formed using ethyl silicate 48, and a hydrolysis reaction is promoted to form a porous silica-containing layer (5 nm thick) from the alkoxysilane layer. , a multilayer film was prepared. Note that during film formation, the temperature of the base material was heated to 60° C., and a multilayer film was produced at a deposition rate of 0.5 nm/sec. The obtained base material with the multilayer film was processed and attached to a frame for glasses to produce glasses. The produced glasses were stored in a dark place in a glasses case for 3 months. After that, when water droplets were attached to the lens, the water droplets wetted and spread on the lens, maintaining good visibility. The contact angle of water at that time was 5°. Furthermore, even after the water had dried, no water marks remained and good visibility was maintained.

The multilayer film of the present disclosure can be used for optical filters, optical lenses, daylighting lenses, optical films, optical prisms, eyeglass lenses, photographic lenses, vehicle door mirrors, plate glass, condensing lenses, display cover glasses, touch panels, and various films. It can be used for covers that protect optical components, such as surveillance camera covers, in-vehicle camera covers, and in-vehicle sensor covers.
Further, the optical member of the present disclosure is applicable to digital cameras, digital video cameras, action cameras, endoscopes, lens barrels, glasses, sensors, binoculars, telescopes, surveillance cameras, in-vehicle cameras, smartphones, tablet PCs, weather cameras, live cameras, etc. It can be used as optical equipment such as cameras, protective goggles, underwater glasses, head-mounted displays, sunglasses, smart glasses, face shields, helmet shields, vehicle mirrors, bathroom mirrors, and covers to protect them.

The present disclosure includes the following embodiments.
(1)
directly on the surface of the base material or through another layer,
a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure;
A layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer containing porous silica having a thickness of 2 nm or more and 10 nm or less and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm is provided on the upper layer side of the layer containing silicon oxide. multilayer film.
(2)
The multilayer film according to (1), wherein the cerium oxide in the layer containing cerium oxide has a composition of CeO _x (x is 1.5 or more and 2.0 or less).
(3)
The multilayer film according to (1) or (2), wherein the content ratio of cerium oxide in the total amount of substances constituting the layer containing cerium oxide is 85% by mass or more.
(4)
The multilayer film according to any one of (1) to (3), wherein the content ratio of silicon oxide in the total amount of substances constituting the layer containing silicon oxide is 65% by mass or more.
(5)
The multilayer film according to any one of (1) to (4), wherein the porous silica is formed by a hydrolysis reaction of alkoxysilane.
(6)
The multilayer film according to (5), wherein the alkoxysilane is methyl polysilicate, ethyl polysilicate, propyl polysilicate, or butyl polysilicate.
(7)
An optical member comprising the multilayer film according to any one of (1) to (6).
(8)
Eyeglasses comprising the optical member according to (7).
(9)
A step of forming a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure directly or through another layer on the surface of the base material;
forming a layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer of alkoxysilane is formed on the upper layer side of the layer containing silicon oxide, and is hydrolyzed to form a porous film having a thickness of 2 nm or more and 10 nm or less, and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm. and forming a layer containing silica.

This application claims priority based on Japanese Patent Application No. 2022-144032, which is a Japanese patent application filed on September 9, 2022, and the entire contents thereof are incorporated herein by reference.

11 Base material 12 Other layers 13 Layer containing cerium oxide 14 Layer containing silicon oxide 15 Layer containing porous silica 21 Eyeglass lens having the multilayer film of the present disclosure 22 Eyeglass frame having the optical member of the present disclosure

Claims

directly on the surface of the base material or through another layer,
a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure;
A layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer containing porous silica having a thickness of 2 nm or more and 10 nm or less and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm is provided on the upper layer side of the layer containing silicon oxide. multilayer film.
The multilayer film according to claim 1, wherein the composition of cerium oxide in the layer containing cerium oxide is CeO x (x is 1.5 or more and 2.0 or less).
The multilayer film according to claim 1, wherein the content ratio of cerium oxide in the total amount of substances constituting the layer containing cerium oxide is 85% by mass or more.
The multilayer film according to claim 1, wherein the content ratio of silicon oxide in the total amount of substances constituting the layer containing silicon oxide is 65% by mass or more.
The multilayer film according to claim 1, wherein the porous silica is formed by a hydrolysis reaction of alkoxysilane.
The multilayer film according to claim 5, wherein the alkoxysilane is methyl polysilicate, ethyl polysilicate, propyl polysilicate, or butyl polysilicate.
An optical member comprising the multilayer film according to any one of claims 1 to 6.
Eyeglasses comprising the optical member according to claim 7.
A step of forming a layer containing cerium oxide having a thickness of 70 nm or more and 300 nm or less and having a cubic polycrystalline structure directly or through another layer on the surface of the base material;
forming a layer containing silicon oxide with a thickness of 50 nm or more and 240 nm or less and a refractive index of 1.46 or more and 1.65 or less at a wavelength of 500 nm on the upper layer side of the layer containing cerium oxide;
A layer of alkoxysilane is formed on the upper layer side of the layer containing silicon oxide, and is hydrolyzed to form a porous film having a thickness of 2 nm or more and 10 nm or less, and a refractive index of 1.33 or more and 1.45 or less at a wavelength of 500 nm. and forming a layer containing silica.