Optical components and lens units

Abstract

To provide an optical member including a functional film that excels in hydrophilic property and rigidity.SOLUTION: An optical member manufacturing method is a method for manufacturing an optical member 1 comprising a light permeable member 2 and a functional film 3 that covers the light permeable member 2, and the method includes a functional film formation step for applying a coating liquid for functional film formation to the light permeable member 2 so as to form the functional film 3. The coating liquid for functional film formation contains a photocatalyst particle, a binder raw material, and a solvent. The binder raw material includes a silicate monomer and a silicate oligomer. The ratio of the substance amount of the silicate oligomer to the sum total of the substance amount of the silicate monomer and the substance amount of the silicate oligomer is 3.5 mol% to 28.0 mol% inclusive.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to ,light optical members and lens unit .

Background Art

[0002] An optical member includes, for example, a translucent member and a functional film that coats the surface of the translucent member. The above-described functional film has, for example, hydrophilicity.

[0003] (a) An aqueous solution containing an amorphous silicate compound obtained by hydrolytic condensation of a tetrafunctional silicon compound having a purity of 99.0% by mass or more in an aqueous medium in the presence of a basic compound at a temperature of room temperature or higher and 170°C or lower, (b) water, and (c) optionally alcohol, ketone, surfactant, or a combination of two or more thereof in a proportion of 30% by mass or less is known (for example, Patent Document 1). The solid content concentration of the amorphous silicate compound contained in this inorganic hydrophilic coating liquid is 0.01% by mass or more and 2.0% by mass or less. The pH of this inorganic hydrophilic coating liquid is 5 or more and 8 or less. This inorganic hydrophilic coating liquid can be used for forming the above-described functional film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the functional film formed by the inorganic hydrophilic coating liquid described in Patent Document 1 tends to have insufficient hardness.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide an optical member having a functional film excellent in hydrophilicity and hardness. [Means for solving the problem]

[0007] The exemplary optical section of the present invention The material is , light-transmitting member and It has hydrophilic properties, The light-transmitting member comprises a functional film covering the light-transmitting member. The functional film contains photocatalytic particles and a binder. The indentation hardness of the functional film is 1000 N / mm². 2 That's all.

[0008] Exemplary examples of the present invention The lens unit comprises a plurality of lenses. At least one of the plurality of lenses is the optical element described above. [Effects of the Invention]

[0009] An exemplary version of the present invention can provide an optical component having a functional film with excellent hydrophilicity and hardness. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of an optical member formed by an example of a method for manufacturing an optical member according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of an optical member formed by a modified example 1 of the manufacturing method for an optical member according to an embodiment of the present invention. [Figure 3] Figure 3 is a graph showing the relationship between the proportion of silicate oligomers (α) and the contact angle for the functional film formed in the example. [Figure 4] Figure 4 is a graph showing the relationship between the proportion of silicate oligomers (α) and the indentation hardness of the functional film formed in the example. [Figure 5] Figure 5 is a graph showing the relationship between the proportion of silicate oligomers (α) and the gel fraction for the sample films formed in the examples. [Figure 6] Figure 6 is a photograph showing the results of the wiping test conducted in the example. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings as appropriate. In the drawings, the same or corresponding parts are denoted by the same reference numerals and will not be repeated in the description. The dimensions of each component in the drawings are not necessarily the same as the dimensions of the actual components.

[0012] In this specification, "thickness" refers to the average thickness. "Anti-reflective coating thickness" is measured using a scanning electron microscope (e.g., JEOL Ltd. "JSM-7900F"). "Functional coating thickness" is measured using a contact-type film thickness gauge (e.g., Bruker Corporation "DekTakXT-S").

[0013] <Method for manufacturing optical components> A method for manufacturing an optical member according to the first embodiment of the present invention is a method for manufacturing an optical member comprising a light-transmitting member and a functional film covering the light-transmitting member, comprising a functional film forming step of forming a functional film by applying a functional film forming coating solution to the light-transmitting member. The functional film forming coating solution contains photocatalytic particles, a binder raw material, and a solvent. The binder raw material contains a silicate monomer and a silicate oligomer. The ratio of the amount of silicate oligomer to the sum of the amounts of silicate monomer and silicate oligomer (hereinafter sometimes referred to as the silicate oligomer ratio (α)) is 3.5 mol% or more and 28.0 mol% or less.

[0014] The optical member formed by the manufacturing method of the optical member according to this embodiment is suitable, for example, as an optical member used in an optical unit comprising one or more optical members (particularly an optical unit used outdoors). The above-described optical member is particularly suitable as the optical member located furthest toward the object among the one or more lenses provided in the optical unit (hereinafter sometimes referred to as the first optical member). When the above-described optical member is used as the first optical member, it is usually used with the functional film side facing toward the object. Specifically, the above-described optical member is suitable as a lens for a lens unit of an in-vehicle camera for monitoring the surroundings of a vehicle.

[0015] The above optical member includes a functional film. The functional film is a hydrophilic film having photocatalytic activity. Even when water adheres to the functional film of the above optical member, the adhered water thinly spreads and wets on the functional film, so that water droplets are hardly formed. Therefore, the above optical member can suppress the deterioration of optical performance due to the adhesion of water droplets. Here, a known functional film is formed using a known coating liquid for forming a functional film containing, for example, photocatalytic particles and silicate oligomers. The known functional film formed by the above known coating liquid for forming a functional film contains photocatalytic particles and a binder. The binder includes a cured silicate. Both the photocatalytic particles and the cured silicate are excellent in hydrophilicity. The above known functional film can exhibit excellent hydrophilicity by containing the photocatalytic particles and the cured silicate. On the other hand, the above known functional film tends not to have a sufficiently high hardness. Therefore, when the surface of the above known functional film is wiped to remove dirt (for example, mud and dust) adhering to the surface, scratches tend to occur easily on the surface.

[0016] The inventors have discovered that a functional film with excellent hardness can be formed by using a coating solution for forming a functional film that contains silicate monomers and silicate oligomers, and in which the proportion of silicate oligomers (α) is above a certain level. This phenomenon is judged to be because the addition of both silicate monomers and silicate oligomers to the coating solution for forming a functional film allows the curing of silicate (e.g., hydrolysis condensation) to proceed efficiently. On the other hand, the inventors have discovered that when the proportion of silicate oligomers (α) in the coating solution for forming a functional film is above a certain level, the hydrophilicity of the formed functional film decreases. This phenomenon is judged to occur for the following reasons. First, in the formation of a functional film, the silicate monomers and silicate oligomers contained in the coating solution for forming a functional film do not completely cure and remain in an unreacted state. Therefore, when the proportion of silicate oligomers (α) in the coating solution for forming a functional film is increased, the amount of silicate oligomers remaining in the functional film also increases. Here, silicate oligomers have lower hydrophilicity compared to silicate monomers. Thus, functional films formed by a coating solution for forming functional films with a certain or higher proportion of silicate oligomers (α) contain a relatively large amount of silicate oligomers and therefore have low hydrophilicity. The present invention is based on these findings. That is, in the method for manufacturing optical components according to this embodiment, a coating solution for forming functional films is used that contains silicate monomers and silicate oligomers, and the proportion of silicate oligomers (α) is 3.5 mol% or more, so a functional film with excellent hardness can be formed. Furthermore, in the method for manufacturing optical components according to this embodiment, the proportion of silicate oligomers (α) in the coating solution for forming functional films is 28.0 mol% or less, so a functional film with excellent hydrophilicity can be formed. Because this functional film has excellent hardness, it is less likely to be scratched even when the surface is wiped (excellent wipe resistance).

[0017] The method for manufacturing the optical member according to this embodiment will be further described below with reference to the drawings. Figure 1 is a schematic diagram of an optical member 1 formed by an example of the method for manufacturing the optical member according to this embodiment. The optical member 1 comprises a light-transmitting member 2 and a functional film 3 that covers the light-transmitting member 2.

[0018] [Translucent member] The light-transmitting member 2 has a base material 2a and an antireflection film 2b that coats the base material 2a. However, as shown in Modification 1 described later, the light-transmitting member of the optical member formed by the manufacturing method of the optical member according to the present embodiment may be composed of a single member. The light-transmitting member 2 has light-transmitting properties. That is, the light-transmitting member 2 transmits light. The light-transmitting member 2 may be transparent or translucent.

[0019] The shape of the light-transmitting member 2 is, for example, lens-shaped. When the shape of the light-transmitting member 2 is lens-shaped, the surface of the light-transmitting member 2 on the side of the antireflection film 2b is, for example, a convex surface. When the shape of the light-transmitting member 2 is lens-shaped, the radius of curvature of the lens surface of the light-transmitting member 2 is preferably 10 mm or more and 15 mm or less. When the radius of curvature of the light-transmitting member 2 is less than 10 mm, it tends to be difficult to adjust the thickness of the functional film 3. When the radius of curvature of the light-transmitting member 2 exceeds 15 mm, it tends to be difficult to impart a desired angle of view to the optical member 1.

[0020] (Base material) The base material 2a contains, for example, glass or resin as a main component.

[0021] (Antireflection film) The antireflection film 2b suppresses light reflection. Specifically, by providing the antireflection film 2b, the optical member 1 suppresses the reflection of light that tries to enter the light-transmitting member 2 from the functional film 3 in the light-transmitting member 2.

[0022] The antireflection film 2b may have a single-layer structure or a multilayer structure. The antireflection film 2b contains, for example, a metal or a metal oxide. The antireflection film 2b is, for example, a vapor deposition film or a sputtering film.

[0023] The thickness of the antireflection film 2b is preferably 200 nm or more and 400 nm or less. When the thickness of the antireflection film 2b is less than 200 nm, a sufficient antireflection effect tends not to be obtained. When the thickness of the antireflection film 2b exceeds 400 nm, the productivity of the optical member 1 tends to decrease.

[0024] [Functional membrane] The functional film 3 covers the surface of the light-transmitting member 2 on the side with the anti-reflective film 2b. The functional film 3 contains photocatalytic particles and a binder. The functional film 3 has photocatalytic activity. Specifically, the functional film 3 is hydrophilic. The static contact angle of the functional film 3 with pure water is preferably 30.0° or less, more preferably 20.0° or less, and even more preferably 10.0° or less.

[0025] The thickness of the functional film 3 is preferably 15 nm to 200 nm, and more preferably 20 nm to 180 nm. A thickness of 15 nm or more improves the hardness of the functional film 3. A thickness of 200 nm or less improves the optical properties of the optical component 1.

[0026] (Photocatalyst particles) The photocatalytic particles include primary photocatalytic particles containing a photocatalyst. The photocatalytic particles may also include secondary photocatalytic particles composed of primary photocatalytic particles. The photocatalytic particles may further contain components other than the photocatalyst, as long as they contain a photocatalyst. Examples of components other than the photocatalyst include components that have an electron-capturing effect. Examples of components that have an electron-capturing effect include gold, silver, copper, platinum, palladium, iron, nickel, cobalt, zinc, and copper oxide. The photocatalyst content in the photocatalytic particles is preferably 90% by mass or more, more preferably 99% by mass or more, and even more preferably 100% by mass.

[0027] Examples of photocatalysts contained in the photocatalytic particles include titanium dioxide, strontium titanate, zinc oxide, silicon carbide, gallium phosphate, cadmium sulfide, cadmium selenide, and molybdenum trisulfide. It is preferable that the photocatalytic particles contain titanium dioxide. The inclusion of titanium dioxide in the photocatalytic particles further improves the photocatalytic activity of the functional film 3.

[0028] Examples of titanium dioxide include anatase-type titanium dioxide, rutile-type titanium dioxide, and brookite-type titanium dioxide. From the viewpoint of photocatalytic activity, anatase-type titanium dioxide is preferred.

[0029] The average particle size of the photocatalytic particles is preferably between 1 nm and 20 nm, and more preferably between 5 nm and 15 nm. Having an average particle size of 1 nm to 20 nm improves the light transmittance of the optical component 1.

[0030] (Binder) The binder contains silicate cured products. These silicate cured products are produced by a curing reaction (e.g., hydrolysis condensation) of silicate monomers and silicate oligomers.

[0031] [Method for manufacturing optical components] A method for manufacturing the optical component 1 is described below. The method for manufacturing the optical component 1 comprises an anti-reflective film forming step of obtaining a translucent component 2 by forming an anti-reflective film 2b on a substrate 2a, and a functional film forming step of forming a functional film 3 by applying a functional film forming coating solution to the translucent component 2 (specifically, on the surface with the anti-reflective film 2b). However, a commercially available translucent component 2 may be used in the method for manufacturing the optical component 1. In this case, the anti-reflective film forming step may be omitted.

[0032] [Anti-reflection film formation process] In this process, the method for forming the anti-reflective film 2b is not particularly limited, and known anti-reflective film formation methods (for example, sputtering and vapor deposition) can be used.

[0033] [Functional film formation process] The coating solution used in this process for forming a functional film contains photocatalytic particles, a binder raw material, and a solvent. The coating solution for forming a functional film may further contain other components. The binder raw material includes silicate monomers and silicate oligomers.

[0034] The binder raw material may contain only silicate monomers and silicate oligomers, or it may contain other components (for example, silica). The total content of silicate monomers and silicate oligomers in the binder is preferably 80% by mass or more, more preferably 99% by mass or more, and even more preferably 100% by mass.

[0035] Silicate monomers are silicate compounds that do not contain siloxane bonds (Si-O-Si) in their molecules. Silicate oligomers are silicate compounds that contain one or more siloxane bonds (for example, two to six) in their molecules.

[0036] The molecular weight of the silicate monomer is preferably between 120 and 210. Setting the molecular weight of the silicate monomer to between 120 and 210 further improves the hardness of the functional film 3. Furthermore, the molecular weight of the silicate oligomer is preferably between 200 and 1000, and more preferably between 600 and 850. Setting the molecular weight of the silicate oligomer to between 200 and 1000 further improves the hardness of the functional film 3. Note that when the binder contains multiple silicate monomers, the molecular weight of the silicate monomer refers to the number-average molecular weight. Similarly, when the binder contains multiple silicate oligomers, the molecular weight of the silicate oligomer refers to the number-average molecular weight.

[0037] The silicate monomer preferably contains a compound represented by the following general formula (1) (hereinafter sometimes referred to as compound (1)). Furthermore, the silicate oligomer preferably contains a compound represented by the following general formula (2) (hereinafter sometimes referred to as compound (2)). The inclusion of compound (1) in the silicate monomer and compound (2) in the silicate oligomer further improves the hardness and hydrophilicity of the functional film 3. Si(OR1)n(OH)(4-n)···(1) SimO(m-1)(OR2)(2m+2)···(2)

[0038] In general formula (1), R1 represents an organic group having 1 to 8 carbon atoms. n represents an integer from 1 to 4. In general formula (2), R2 represents an alkyl group having 1 to 4 carbon atoms. m represents an integer from 2 to 6.

[0039] In general formula (1), when n represents an integer of 2 or more, the multiple R1s may be the same or different from each other, but it is preferable that they be the same. In general formula (2), the multiple R2s may be the same or different from each other, but it is preferable that they be the same. The details of compound (1) and compound (2) will be described below.

[0040] (Compound (1)) In general formula (1), the organic group having 1 to 8 carbon atoms represented by R1 is, for example, an alkyl group having 1 to 4 carbon atoms and an alkoxysilyl group having 1 to 8 carbon atoms. Examples of alkyl groups having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of alkoxysilyl groups having 1 to 8 carbon atoms include a trimethoxysilyl group and a triethoxysilyl group. The organic group having 1 to 8 carbon atoms represented by R1 is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group.

[0041] As compound (1), a compound represented by the following general formula (1') (hereinafter sometimes referred to as ethyl silicate monomer) is preferred. The n in the following general formula (1') is the same as the n in general formula (1). Si(OC2H5)n(OH)(4-n)···(1')

[0042] The silicate monomer may contain a mixture of two or more compounds (1). In this case, the average value of n in the general formula (1) in the mixture of compounds (1) is preferably 2.0 or more and 4.0 or less, and more preferably 3.0 or more and 4.0 or less.

[0043] Let's explain how to calculate the average value of n in general formula (1) with an example. Assume that the mixture of compound (1) contains equal moles of compound (1) where n is 1, compound (1) where n is 2, compound (1) where n is 3, and compound (1) where n is 4 in general formula (1). In this case, the average value of n in general formula (1) for the mixture of compound (1) is 2.5.

[0044] (Compound (2)) In general formula (2), examples of alkyl groups having 1 to 4 carbon atoms represented by R2 include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. A methyl or ethyl group is preferred as the alkyl group having 1 to 4 carbon atoms represented by R2.

[0045] Compound (2) is preferably a compound represented by the following general formula (2') (hereinafter sometimes referred to as an ethyl silicate oligomer). The m in the following general formula (2') is the same as the m in general formula (2). SimO(m-1)(OC2H5)(2m+2)···(2')

[0046] The silicate oligomer may contain a mixture of two or more compounds (2). In this case, the average value of m in the general formula (2) in the mixture of compounds (2) is preferably 4.0 or more and 6.0 or less, and more preferably 4.5 or more and 5.5 or less.

[0047] Let's explain the method for calculating the average value of m in general formula (2) with an example. Assume that the mixture of compound (2) contains equal moles of compound (2) where m is 2, compound (2) where m is 3, compound (2) where m is 4, compound (2) where m is 5, and compound (2) where m is 6. In this case, the average value of m in general formula (2) for the mixture of compound (2) is 4.0.

[0048] The proportion of silicate oligomers (α) is 3.5 mol% or more and 28.0 mol% or less, preferably 5.0 mol% or more and 28.0 mol% or less, and more preferably 10.0 mol% or more and 20.0 mol% or less. When the proportion of silicate oligomers (α) is 3.5 mol% or more, the functional film 3 exhibits excellent hardness. When the proportion of silicate oligomers (α) is 28.0 mol% or less, the functional film 3 exhibits excellent hydrophilicity.

[0049] A water-based solvent is preferred as the solvent for the coating solution for forming functional films. The water-based solvent contains water and additives as needed. Examples of additives include organic acids, alcohol compounds, and ammonia. The preferred content of additives in the water-based solvent is more than 0% by mass and 20% by mass or less. Examples of organic acids include formic acid, acetic acid, propionic acid, succinic acid, citric acid, and malic acid. Examples of alcohol compounds include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butanol.

[0050] A wet process is preferred as the application method for the coating solution for forming a functional film. Examples of wet processes include spin coating, roll coating, bar coating, dip coating, spray coating, and combinations thereof (e.g., dip-spin coating). Spin coating, dip coating, or dip-spin coating are preferred as wet processes.

[0051] When applying a coating solution for forming a functional film using the spin coating method or the dip spin coating method, a rotation speed of 500 rpm to 10,000 rpm is preferred.

[0052] The solid content concentration of photocatalytic particles in the coating solution for forming a functional film is preferably 1.0% by mass or more and 15.0% by mass or less, and more preferably 2.0% by mass or more and 6.0% by mass or less. The solid content concentration of binder raw materials in the coating solution for forming a functional film is preferably 85.0% by mass or more and 99.0% by mass or less, and more preferably 94.0% by mass or more and 98.0% by mass or less. The solid content concentration of the coating solution for forming a functional film is preferably 0.1% by mass or more and 10.0% by mass or less, and more preferably 0.2% by mass or more and 1.0% by mass or less.

[0053] In this process, before applying the coating solution for forming the functional film, the surface of the translucent member 2 on the side with the anti-reflective film 2b may be subjected to surface treatment. Examples of surface treatments include plasma treatment, electron beam treatment, corona treatment, and flame treatment. Examples of plasma treatments include high-frequency discharge plasma treatment or atmospheric pressure glow discharge plasma treatment. Multiple surface treatments can also be used in combination.

[0054] In this process, it is preferable to perform a heat treatment after applying the functional film-forming coating solution. The heat treatment removes volatile components from the functional film-forming coating solution and promotes the curing reaction. For example, the heating conditions can be a treatment temperature of 60°C to 200°C and a treatment time of 10 minutes to 10 hours.

[0055] <Example 1> Next, with reference to Figure 2, an optical member 11 formed by an example of a manufacturing method for the optical member according to this embodiment will be described. The optical member 11 in Figure 2 is a modified example 1 of the optical member 1 in Figure 1. The optical member 11 comprises a light-transmitting member 12 and a functional film 13 covering the light-transmitting member 12.

[0056] The manufacturing method for the optical component 11 in Figure 2 differs from that of the optical component 1 in Figure 1 only in that the translucent component 12 is a single component. Therefore, explanations that overlap with the manufacturing method of optical component 1 are omitted. The translucent component 12 is the component corresponding to the base material 2a of the optical component in Figure 1. Since the optical component 11 does not have an anti-reflective coating 2b, it can be manufactured at a lower cost than the optical component 1 in Figure 1.

[0057] [Other variations] The method for manufacturing an optical member according to this embodiment has been described above with reference to the drawings. However, the method for manufacturing an optical member according to this embodiment is not limited to the method for manufacturing optical member 1 shown in Figure 1 and the method for manufacturing optical member 11 shown in Figure 2.

[0058] The optical member formed by the optical member according to this embodiment may further include other components besides the light-transmitting member and the functional film. The functional film preferably has a single-layer structure, but may also have a multilayer structure. Furthermore, the functional film preferably covers the entire surface of the light-transmitting member, but does not necessarily have to cover the entire surface.

[0059] <Second Embodiment: Optical Component> The optical member according to the second embodiment of the present invention is formed by the method for manufacturing the optical member according to the first embodiment described above. Since the details of the optical member formed by the method for manufacturing the optical member according to the first embodiment have been described above, redundant explanations will be omitted. [Examples]

[0060] <Manufacturing of optical components A> Optical components of Examples 1-4 and Comparative Examples 1-3 were manufactured using the following method. In the manufacture of each optical component, a first coating solution and a second coating solution were prepared as coating solutions for forming functional films. The details of the first and second coating solutions are described below.

[0061] (First application solution) A first coating solution was prepared by mixing ethyl silicate monomer ("Tetraethyl Orthosilicate (TEOS)" manufactured by Tama Chemical Industry Co., Ltd., purity: 99.9% by mass or higher), a photocatalytic dispersion containing anatase-type titanium dioxide particles ("Sagan Coat (Registered Trademark) TO-85" manufactured by Japan Photocatalyst Center Co., Ltd., solid content concentration: 0.85% by mass, solvent: water) and water to the following composition. The first coating solution contained silicate monomer (solid content equivalent concentration: 96% by mass), titanium dioxide particles which are photocatalytic particles (solid content equivalent concentration: 4% by mass), and solvent (water) (solid content concentration: 0.45% by mass). The average value of n in general formula (1) of the ethyl silicate monomer was approximately 4.0. The number-average molecular weight of the ethyl silicate monomer contained in the first coating solution was approximately 208. The average particle size of the titanium dioxide particles contained in the first coating solution was 10 nm.

[0062] (Second application solution) As the second coating solution, a solution containing ethyl silicate oligomer and a solvent (Ethyl Silicate 40, manufactured by Colcoat Co., Ltd., solid content concentration: 0.34% by mass, solvent: ethanol) was prepared. The ethyl silicate oligomer contained in the second coating solution was a mixture of several types of ethyl silicate oligomers with different values ​​of m in general formula (2). The average value of m in general formula (2) of the ethyl silicate oligomer contained in the second coating solution was 5.0. The number-average molecular weight of the ethyl silicate oligomer contained in the second coating solution was 745.2.

[0063] [Example 1] The optical component of Example 1 was manufactured by the following method. First, a lens (TAFD-5G, manufactured by HOYA Corporation, composition: glass, diameter 12.9 mm) was prepared as a substrate. One surface of this lens was concave (radius of curvature 3 mm), and the other surface was convex (radius of curvature 12 mm). Next, an anti-reflective coating was formed on the convex surface of the lens. The anti-reflective coating contained an SiO2 layer, a TiO2 layer, and a Ta2O5 layer. The total thickness of the anti-reflective coating was approximately 300 nm. This resulted in a translucent component comprising the substrate and the anti-reflective coating. Next, the surface of the translucent component with the anti-reflective coating side was subjected to surface treatment (30 seconds). For the surface treatment, plasma treatment was performed using a plasma surface modification apparatus.

[0064] Next, 8.1 g of the first coating solution and 1.9 g of the second coating solution were mixed. The resulting mixture was used as a coating solution for forming a functional film. In the coating solution for forming a functional film, the ratio of the amount of silicate oligomer (8.6 × 10⁻⁶ moles) to the total amount of silicate monomer and silicate oligomer (1.8 × 10⁻⁴ moles) was 4.9 mol%.

[0065] The above-mentioned functional film-forming coating solution was applied to the anti-reflective coating of the translucent member after plasma treatment using a spin-coating method. A spin coater (MS-B100, manufactured by Mikasa Corporation) was used for the spin-coating method. The application conditions were a rotation speed of 8000 rpm and a rotation time of 30 seconds. After application, a heat treatment was performed at 120°C for 30 minutes. This formed a functional film on the translucent member. As a result, an optical member of Example 1 was obtained in which the substrate, anti-reflective coating, and functional film were laminated in this order.

[0066] The thickness of the functional film on the optical component in Example 1 was measured using a contact-type film thickness gauge (Bruker's "DekTakXT-S"). The thickness of the functional film on the optical component in Example 1 was 20 nm.

[0067] [Examples 2-4 and Comparative Examples 1-3] Except for the following modifications, the optical components of Examples 2-4 and Comparative Examples 1-3 were manufactured using the same method as the manufacturing method of the optical component of Example 1. In the manufacturing of the optical components of Examples 2-4 and Comparative Examples 1-3, the first coating solution and the second coating solution were mixed in the proportions shown in Table 1 below when preparing the coating solution for forming the functional film. In the manufacturing of the optical component of Comparative Example 1, the first coating solution was used as is as the coating solution for forming the functional film.

[0068] <Evaluation of hydrophilicity of functional membranes> For the optical components of Examples 1-4 and Comparative Examples 1-3, the static contact angle of the functional film with respect to pure water (hereinafter sometimes simply referred to as "contact angle") was measured. An automatic contact angle meter (DMo-601, manufactured by Kyowa Interface Science Co., Ltd.) was used as the measuring instrument for the contact angle measurement. The measurement environment was set to a temperature of 23°C ± 3°C and a relative humidity of 50% ± 10%. The measurement results are shown in Table 1 below. In this example, a contact angle of 15° or less of the functional film can be considered good.

[0069] Figure 3 is a graph showing the relationship between the proportion of silicate oligomers (α) in the functional film and the contact angle for each optical component.

[0070] In Table 1 below, "First Coating Solution [mass%]" and "Second Coating Solution [mass%]" represent the mass percentages of the first and second coating solutions used to prepare the functional film-forming coating solution, respectively. "Percentage (α) [mol%]" indicates the percentage (α) of silicate oligomers in the functional membrane. The same explanations apply to Tables 2 and 3 below, which will be discussed later.

[0071] [Table 1]

[0072] As shown in Table 1 and Figure 3, the optical components of Comparative Example 1 and Examples 1-4 had a silicate oligomer ratio (α) of 28.0 mol% or less in the functional film. The optical components of Comparative Example 1 and Examples 1-4 had good contact angles of the functional film. On the other hand, the optical components of Comparative Examples 2 and 3 had a silicate oligomer ratio (α) of 28.0 mol% or more in the functional film. The optical components of Comparative Examples 2 and 3 did not have good contact angles of the functional film.

[0073] <Manufacturing of optical components B> The optical components of Examples 1-4 and Comparative Examples 1-3 described above were manufactured again.

[0074] <Evaluation of the hardness of functional membranes> The hardness of the functional films of the optical components in Examples 1-4 and Comparative Examples 1-3 was measured. Specifically, a nanoindenter (ENT-NEXUS, manufactured by Elionix Co., Ltd.) was used to perform nanoindentation (ultra-micro-indentation hardness) tests on the functional films of each optical component in accordance with "ISO 14577-1". In the nanoindentation tests, the indentation depth was set to 50 nm. The measured hardness of the functional films of each optical component is shown in Table 2 below. In this example, an indentation hardness of 1000 N / mm2 or higher was considered good.

[0075] Figure 4 is a graph showing the relationship between the proportion of silicate oligomers (α) in the functional film and the indentation hardness for each optical component.

[0076] [Table 2]

[0077] As shown in Table 2 and Figure 4, the optical components of Examples 1 to 4 had a silicate oligomer ratio (α) in the functional film between 3.5 mol% and 28.0 mol%. The optical components of Examples 1 to 4 exhibited good functional film hardness. On the other hand, the optical component of Comparative Example 1 had a silicate oligomer ratio (α) in the functional film of less than 3.5 mol%. The optical component of Comparative Example 1 did not exhibit good functional film hardness. The optical components of Comparative Examples 2 and 3 had a silicate oligomer ratio (α) in the functional film of more than 28.0 mol%. While the optical components of Comparative Examples 2 and 3 exhibited good functional film hardness, as described above, the contact angle of the functional film was judged to be poor.

[0078] Based on these results, it can be concluded that if the proportion of silicate oligomers (α) in the functional film of an optical component is 3.5 mol% or higher, both the hydrophilicity and hardness of the functional film are good.

[0079] <Evaluation of the gel fraction of the binder> The relationship between the proportion of silicate oligomers (α) in the binder raw material and the curing rate of the binder raw material was investigated using the following method. First, sample coating solutions containing binder raw materials (silicate monomer and silicate oligomer) but without photocatalytic particles were prepared. Five types of sample coating solutions with different proportions of silicate oligomers (α) were prepared. Sample films were formed using each sample coating solution, and the gel fraction of the binder in the formed sample films was measured. Here, it was determined that the faster the curing rate of the binder raw material contained in the sample coating solution, the higher the gel fraction of the binder in the formed sample film. Therefore, the gel fraction of the binder in the sample film was used as an indicator to estimate the curing rate of the binder raw material contained in the sample coating solution. Next, the curing rate (gel fraction) of the binder raw material was investigated when the proportion of silicate oligomers (α) in the binder raw material was increased or decreased. In this study, the binder raw materials were cured under mild conditions to facilitate the estimation of their curing rate. The results are shown in Table 3 below.

[0080] First, ethyl silicate monomer ("Tetraethyl Orthosilicate (TEOS)" manufactured by Tama Chemical Industry Co., Ltd., purity: 99.9% by mass or higher) and water were mixed to the following composition to prepare the 1' coating solution. The 1' coating solution contained silicate monomer and solvent (water) (solid content concentration: 0.45% by mass).

[0081] Next, sample coating solutions A to E were prepared by mixing the first coating solution and the second coating solution described above in the proportions shown in Table 3 below.

[0082] Next, sample coating solutions A to E, which were to be evaluated, were applied to the plasma-treated glass substrate using the spin-coating method. A spin coater (MS-B100, manufactured by Mikasa Corporation) was used for the spin-coating method. The application conditions were a rotation speed of 8000 rpm and a rotation time of 30 seconds. After application, the substrate was left to stand at room temperature (23°C) for 130 hours. This formed a sample film on the glass substrate. The thickness of the sample film was measured using a contact-type film thickness gauge (DekTakXT-S, manufactured by Bruker). The thickness of the sample film was 20 nm.

[0083] Next, the mass (mass A) of the glass substrate on which the sample film was formed was measured. The value obtained by subtracting the mass of the glass substrate from mass A was defined as the "mass of the binder." Then, the glass substrate on which the sample film was formed was immersed in toluene at 23°C for 24 hours. After the immersion treatment, the glass substrate on which the sample film was formed was thoroughly washed and dried, and its mass (mass B) was measured. The value obtained by subtracting the mass of the glass substrate from mass B was defined as the "mass of the gel." The gel fraction of the binder was determined based on the following formula. Gel fraction [mass %] = 100 × Mass of gel [g] / Mass of binder [g]

[0084] Figure 5 is a graph showing the relationship between the proportion of silicate oligomers (α) and the gel fraction for each sample membrane.

[0085] [Table 3]

[0086] As shown in Table 3 and Figure 5, the gel fraction increased as the proportion of silicate oligomers (α) increased during the formation of the sample film. In particular, the gel fraction increased sharply when the proportion of silicate oligomers (α) was increased from 0.0 mass% to 3.9 mass%. From the above, it is determined that the curing speed of the binder raw material can be improved by setting the proportion of silicate oligomers (α) to 3.5 mass% or more. Furthermore, it is determined that, similar to the sample coating solution without photocatalytic particles, the curing speed of the binder raw material can be improved by setting the proportion of silicate oligomers (α) to 3.5 mass% or more in the functional film forming coating solution containing photocatalytic particles. In Examples 1 to 4 described above, the excellent hardness of the functional films of the optical components was determined to be due to the efficient curing of the binder raw material in the functional film forming coating solution.

[0087] The sample film is formed by curing the sample coating solution under mild conditions. Therefore, the gel fraction of the sample film is relatively low, less than 60% by mass. On the other hand, the functional films of the optical components in each example and comparative example are formed by curing the coating solution for functional film formation at high temperatures. Therefore, the gel fraction of the functional films of the optical components in each example and comparative example is estimated to be close to 100% by mass.

[0088] <Evaluation of the wipe resistance of functional films> The optical components of Example 3 and Comparative Example 1 described above were manufactured again. A wiping test was performed on the functional film of each optical component. Specifically, the surface of the functional film of each optical component was photographed with a laser microscope (OLS5000, manufactured by Olympus Corporation) (magnification: 20x). Next, a paper wiper (K-Dry®, manufactured by Nippon Paper Crecia Co., Ltd.) was used to lightly rub the surface of the functional film of each optical component 10 times back and forth. After the wiping test, the surface of the functional film of each optical component was photographed with the laser microscope described above.

[0089] Figure 6 shows laser microscope images of the surface of the functional film of each optical component taken during the wiping test. "A1," "A2," "B1," and "B2" in Figure 6 are as follows. "A1," "A2," "B1," and "B2" in Figure 6 are all at 1x magnification. "S" in Figure 6 indicates a scratch that occurred on the surface of the functional film. A1: Comparative Example 1 (Before the wipe test) A2: Comparative Example 1 (after wiping test) B1: Example 3 (before wiping test) B2: Example 3 (after wiping test)

[0090] As is clear from Figure 6, no scratches were found on the surface of the functional film of the optical component in Example 3 even after the wiping test. On the other hand, scratches were found on the surface of the functional film of the optical component in Comparative Example 1 after the wiping test.

[0091] Based on the above, it is determined that the wipe resistance of the functional film of an optical component is improved when the proportion (α) of silicate oligomers in the functional film is between 3.5 mol% and 28.0 mol%. [Industrial applicability]

[0092] The present invention is suitable for providing optical components for sensors or imaging equipment. [Explanation of symbols]

[0093] 1,11 Optical components 2,12 Translucent material 2a Base material 2b Anti-reflection coating 3,13 Functional membrane

Claims

1. Translucent material, A functional film having hydrophilic properties and covering the light-transmitting member Equipped with, The functional film contains photocatalytic particles and a binder. The indentation hardness of the functional film is 1000 N / mm ２ That's all, The contact angle of the functional membrane with respect to pure water is 30° or less. The binder contains a silicate cured product, The silicate cured product is produced by a curing reaction of silicate monomer and silicate oligomer. The silicate monomer includes a compound represented by the following general formula (1): The silicate oligomer contains a compound represented by the following general formula (2), The ratio of the amount of substance of the silicate oligomer to the sum of the amounts of substance of the silicate monomer and the silicate oligomer is 3.5 mol% or more and 28.0 mol% or less. Optical components. Si (OR1) ｎ (OH) （４－ｎ） ・・・(1) Si ｍ O （ｍ－１） (OR2) （２ｍ＋２） ・・・(2) (In the above general formula (1), R1 represents an organic group having 1 to 8 carbon atoms, and n represents an integer from 1 to 4.) In the general formula (2) above, R2 represents an alkyl group having 1 to 4 carbon atoms, and m represents an integer between 2 and 6.

2. The thickness of the functional film is 15 nm or more and 200 nm or less. The optical member according to claim 1.

3. The photocatalyst content in the aforementioned photocatalyst particles is 90% by mass or more. The optical member according to claim 1 or 2.

4. The aforementioned photocatalytic particles contain anatase-type titanium dioxide. The optical component according to any one of claims 1 to 3.

5. The average particle size of the photocatalytic particles is between 1 nm and 20 nm. The optical member according to any one of claims 1 to 4.

6. The light-transmitting member comprises a base material and an anti-reflective film covering the base material. The thickness of the anti-reflective coating is 200 nm or more and 400 nm or less. The optical component according to any one of claims 1 to 5.

7. The shape of the light-transmitting member is lens-shaped, The surface of the light-transmitting member facing the functional film is a convex surface. The radius of curvature of the convex surface is 10 mm or more and 15 mm or less. The optical component according to any one of claims 1 to 6.

8. Equipped with multiple lenses, At least one of the plurality of lenses is an optical element according to any one of claims 1 to 7. Lens unit.

9. The optical element is the one located closest to the object among the plurality of lenses. The lens unit according to claim 8.

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