阅读说明：本技术 光学构件及其制造方法 (Optical member and method for manufacturing the same ) 是由 渡边友启 加本贵则 嶋谷貴文 中川小百合 田所朋 山本明典 若村纱友里 于 2020-02-20 设计创作，主要内容包括：光学构件包括透光性构件和覆盖所述透光性构件的功能膜。所述功能膜含有：通过紫外线来活化的光催化剂粒子；以及作为磷酸二氧化钛或过氧化钛的特定钛氧化物。所述光催化剂粒子中的至少一部分构成光催化剂二次粒子(4)。光学构件的制造方法包括在透光性构件上形成功能膜的膜形成工序,该功能膜含有通过紫外线来活化的光催化剂粒子和特定钛氧化物。所述特定钛氧化物是磷酸二氧化钛或过氧化钛。所述光催化剂粒子中的至少一部分构成光催化剂二次粒子。(The optical member includes a light-transmissive member and a functional film covering the light-transmissive member. The functional film contains: photocatalyst particles activated by ultraviolet rays; and specific titanium oxides as titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles (4). The method for producing an optical member includes a film formation step of forming a functional film containing photocatalyst particles activated by ultraviolet rays and specific titanium oxide on a light-transmissive member. The specific titanium oxide is titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles.)

1. An optical component, comprising:

a light-transmissive member; and

a functional film covering the light-transmissive member,

the functional film contains:

photocatalyst particles activated by ultraviolet rays; and

a specific titanium oxide which is titanium phosphate or titanium peroxide,

at least a part of the photocatalyst particles constitute photocatalyst secondary particles.

2. The optical component according to claim 1,

the photocatalyst particles contain titanium oxide.

3. Optical component according to claim 1 or 2,

the specific titanium oxide is titanium phosphate oxide.

4. Optical component according to one of claims 1 to 3,

the specific titanium oxide is amorphous.

5. The optical component according to any one of claims 1 to 4,

at least a part of the photocatalyst particles constitute an aggregate,

the aggregate has an average particle diameter of 20nm to 200 nm.

6. Optical component according to one of claims 1 to 5,

the functional film further contains a binder.

7. The optical component according to claim 6,

the functional film includes an adhesive layer containing the adhesive,

the adhesive layer covers the light-transmitting member,

at least a part of the secondary photocatalyst particles is partially embedded in the adhesive layer.

8. Optical component according to one of claims 1 to 7,

the functional film includes a specific titanium oxide layer containing the specific titanium oxide,

at least a part of the photocatalyst secondary particles is partially or completely covered with the specific titanium oxide layer.

9. Optical component according to one of claims 1 to 8,

the photocatalyst secondary particles have an average particle diameter of 10nm to 50 nm.

10. A method for manufacturing an optical member is characterized in that,

the method for manufacturing the optical member includes a film forming step of forming a functional film on a light-transmitting member,

the functional film contains:

photocatalyst particles activated by ultraviolet rays; and

a specific titanium oxide which is titanium phosphate or titanium peroxide,

at least a part of the photocatalyst particles constitute photocatalyst secondary particles.

11. The method for manufacturing an optical member according to claim 10,

the film forming process includes:

a first coating step of applying a first coating liquid containing the photocatalyst particles to the surface of the light-transmissive member; and

and a second coating step of, after the first coating step, further applying a second coating liquid containing titanium dioxide phosphate particles or titanium peroxide particles to the surface of the light-transmissive member.

Technical Field

The present invention relates to an optical member and a method for manufacturing the same.

Background

As a member having a photocatalytic function, a member in which a layer mainly composed of particles having photocatalytic activity is formed on a base material is known (for example, patent document 1). Fine particles having an average particle diameter of less than 0.01 μm are dispersed and blended in the particle layer.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open gazette: japanese patent laid-open No. 9-939

Disclosure of Invention

Technical problem to be solved by the invention

However, when the member described in patent document 1 is used as an optical member, the abrasion resistance of the particle layer is insufficient.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an optical member including a functional film having excellent photocatalytic activity and abrasion resistance.

Technical scheme for solving technical problem

Exemplary optical members of the present invention include: a light-transmissive member; and a functional film covering the light-transmissive member. The functional film contains: photocatalyst particles activated by ultraviolet rays; and a specific titanium oxide which is titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles.

The method for manufacturing an optical member according to an exemplary embodiment of the present invention includes a film formation step of forming a functional film on a light-transmissive member. The functional film contains: photocatalyst particles activated by ultraviolet rays; and a specific titanium oxide which is titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles.

Effects of the invention

The exemplary invention can provide an optical member including a functional film having excellent photocatalytic activity and abrasion resistance.

Drawings

Fig. 1 is a schematic view of an example of an optical member according to a first embodiment of the present invention.

Fig. 2 is a schematic view of modification 1 of the optical member of fig. 1.

Fig. 3 is a schematic view of modification 2 of the optical member of fig. 1.

Fig. 4 is a schematic view showing a step in manufacturing the optical member of fig. 1.

Fig. 5 is a graph showing contact angles of the optical members of example 1, example 2, and comparative example 1.

Fig. 6 is a graph showing contact angles of the optical members of example 1 and comparative example 1.

Detailed Description

Embodiments of the present invention will be described below with reference to the accompanying drawings as appropriate. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

In the present specification, the "average particle diameter" of the particles or aggregates is determined by observation using a Scanning Electron Microscope (SEM). Specifically, any fifty measurement objects are selected from among the measurement objects (particles or aggregates) observed by the SEM image, and the entire image of the measurement objects can be confirmed. For each measurement object, the maximum diameter and the minimum diameter were measured, and the average value thereof was defined as the particle diameter of each measurement object. Then, the average value of the particle diameters of fifty measurement objects was defined as an "average particle diameter". The maximum diameter is the length of the longest line segment among line segments passing through the geometric center of the measurement object and having both ends respectively located at the outer edge of the measurement object. The minimum diameter is the length of the shortest line segment among line segments passing through the geometric center of the measurement object and having both ends respectively located at the outer edge of the measurement object.

In the present specification, "thickness" means an average thickness. The "thickness" is measured by a contact type film thickness measuring instrument (e.g., "DekTakXT-S" manufactured by Bruker Co., Ltd.).

< first embodiment: optical component

An optical member according to a first embodiment of the present invention includes a light-transmissive member and a functional film covering the light-transmissive member. The functional film contains: photocatalyst particles activated by ultraviolet rays; and a specific titanium oxide which is titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles. Hereinafter, the photocatalyst particles activated by ultraviolet rays may be abbreviated as "photocatalyst particles".

The functional film contains photocatalyst particles and thus has excellent photocatalytic activity. Specifically, the functional film has high hydrophilicity. That is, the functional film has high wettability with respect to water. Therefore, when water droplets adhere to the functional film, a water film of almost uniform thickness is formed on the surface of the functional film. Further, even when the hydrophilicity of the functional film decreases with use, the hydrophilicity can be restored by irradiation with ultraviolet rays.

The optical member of the first embodiment has a functional film, and is therefore preferable as an optical member used in an environment where water adheres. The optical member according to the first embodiment is preferably used outdoors, for example. Specifically, the optical member according to the first embodiment is preferable as a lens for an in-vehicle camera for monitoring the periphery of a vehicle.

The optical member of the first embodiment includes a functional film having excellent abrasion resistance and photocatalytic activity. The reason why the functional film is excellent in abrasion resistance and photocatalytic activity is presumed as follows. The titanium phosphate oxide and the titanium peroxide function as a binder for inhibiting the photocatalyst particles from being detached from the functional film. Therefore, the functional film has excellent abrasion resistance. In addition, since titanium oxide phosphate forms a porous layer, ultraviolet rays are easily transmitted therethrough. In addition, titanium peroxide exists as a xerogel in which titanium peroxide particles are connected in a network in the functional film, and thus ultraviolet rays are easily transmitted therethrough. Therefore, even when the photocatalyst particles are coated with titanium phosphate or titanium peroxide, the photocatalyst activity of the photocatalyst particles is not easily lowered. As a result, the functional film is excellent in photocatalytic activity and abrasion resistance.

Preferably, the functional film further contains a binder. In this way, by further including an adhesive in the functional film, the abrasion resistance of the functional film can be further improved. The binder is a component different from the specific titanium oxide.

The optical member 1 of the first embodiment is explained below with reference to fig. 1. Fig. 1 is a schematic view of an optical member 1 of the first embodiment. The optical member 1 includes a light-transmissive member 2 and a functional film 3 covering the light-transmissive member 2.

[ translucent Member ]

As shown in fig. 1, the light-transmissive member 2 is constituted by a single member. However, as shown in modification 1 described below, the light-transmissive member of the optical member according to the first embodiment may be formed of a plurality of members. The light-transmitting member 2 has light-transmitting properties. That is, the light-transmissive member 2 transmits light. The light-transmissive member 2 may be transparent or translucent. The light-transmitting member 2 contains, for example, glass or resin.

The translucent member 2 is, for example, lens-shaped. When the shape of the light-transmitting member 2 is a lens shape, the radius of curvature of the lens surface of the light-transmitting member 2 is preferably 10mm to 15 mm. When the radius of curvature of the light-transmissive member 2 is less than 10mm, the thickness variation of the functional film 3 tends to increase between the central portion of the light-transmissive member 2 and the outer edge portion of the light-transmissive member 2. When the radius of curvature of the light-transmissive member 2 exceeds 15mm, it tends to be difficult to impart a desired angle of view to the optical member 1.

[ functional film ]

The functional film 3 has photocatalytic activity. Specifically, the functional film 3 has hydrophilicity. The static contact angle of the surface of the functional film 3 with respect to pure water is preferably 30.0 degrees or less, more preferably 20.0 degrees or less, and still more preferably 10.0 degrees or less. Hereinafter, the static contact angle with respect to pure water is sometimes abbreviated as "contact angle". Here, the contact angle of the functional film 3 is a value measured in an environment where the temperature is 23 ℃ ± 3 ℃ and the relative humidity is 50% ± 3% after the functional film 3 is sufficiently irradiated with ultraviolet rays. The ultraviolet ray irradiation conditions include a wavelength of 352nm, an irradiation time of 96 hours, and an irradiance of 1mW/cm²。

The functional film 3 covers at least a part of the surface of the light-transmissive member 2. The functional film 3 preferably covers the entire surface of a portion of the surface of the light-transmissive member 2 that is not covered with other members.

The functional film 3 contains photocatalyst particles, specific titanium oxide, and a binder. In the functional film 3, the specific titanium oxide forms a specific titanium oxide layer 5. In the functional film 3, the adhesive forms an adhesive layer 6.

(photocatalyst particles)

The photocatalyst particles are primary particles containing a photocatalyst. At least a part of the photocatalyst particles constitute photocatalyst secondary particles 4. At least a part of the photocatalyst particles may be contained in the functional film 3 in the state of primary particles. The photocatalyst particles may further contain a component other than the photocatalyst as long as they contain the photocatalyst. Examples of the component other than the photocatalyst include a component having an electron-replenishing effect. Examples of the substance having an electron-replenishing effect include gold, silver, copper, platinum, palladium, iron, nickel, cobalt, zinc, and copper oxide. The content of the photocatalyst in the photocatalyst particles is preferably 90% by mass or more, more preferably 99% by mass or more, and still more preferably 100% by mass.

Examples of the photocatalyst contained in the photocatalyst particles include titanium oxide, strontium titanate, zinc oxide, silicon carbide, gallium phosphate, cadmium sulfide, cadmium selenide, and molybdenum trisulfide. Preferably, the photocatalyst particles contain titanium oxide. By containing titanium oxide in the catalyst particles, the photocatalytic activity of the functional film 3 can be further improved.

Examples of the titanium oxide include anatase type titanium oxide, rutile type titanium oxide, and brookite type titanium oxide. The titanium oxide is preferably anatase-type titanium oxide from the viewpoint of photocatalytic activity.

The average particle diameter of the photocatalyst particles is preferably 1nm to 20nm, more preferably 5nm to 18 nm. The light transmittance of the optical member 1 can be improved by setting the average particle diameter of the photocatalyst particles to 1nm or more and 20nm or less.

From the viewpoint of improving the photocatalytic activity of the functional film 3, it is preferable that a part of the photocatalytic secondary particles 4 is partially or completely exposed to the surface of the functional film 3. Specifically, the proportion of the particles (hereinafter, sometimes referred to as exposed particles) which are partially or completely exposed to the surface of the functional film 3 among all the photocatalyst secondary particles 4 is preferably 1% to 90%, more preferably 5% to 80%, and still more preferably 10% to 70%. The exposed particle ratio is calculated from the ratio of the number of exposed particles in any one hundred of the photocatalyst secondary particles 4 by observing the cross section of the functional film 3 with an electron microscope.

The average particle diameter of the photocatalyst particles 4 is preferably 10nm to 90nm, and more preferably 10nm to 50 nm. When the average particle diameter of the secondary photocatalyst particles 4 is 10nm or more, the secondary photocatalyst particles 4 are easily exposed from the adhesive layer 6. As a result, the photocatalytic activity of the functional film 3 can be further improved. The light transmittance of the functional film 3 can be improved by setting the average particle diameter of the secondary photocatalyst particles 4 to 50nm or less.

At least a part of the photocatalyst secondary particles 4 constitutes an aggregate 4 a. The aggregate 4a is composed of a plurality of photocatalyst secondary particles 4. By forming the aggregates 4a of the secondary photocatalyst particles 4 in this manner, the secondary photocatalyst particles 4 are easily exposed to the surface of the functional film 3. As a result, the photocatalytic activity of the functional film 3 can be further improved. Further, by constituting the aggregates 4a of the secondary photocatalyst particles 4, the light transmittance of the functional film 3 can be improved. The average particle diameter of the aggregate 4a is preferably 20nm to 200nm, more preferably 60nm to 150 nm. By setting the average particle diameter of the aggregates 4a to 20nm or more, the photocatalyst secondary particles 4 are more easily exposed to the surface of the functional film 3. The light transmittance of the functional film 3 can be further improved by setting the average particle diameter of the aggregates 4a to 200nm or less. The plurality of aggregates 4a may be in contact with the adhesive layer 6. By bringing the plurality of aggregates 4a into contact with the adhesive layer 6 in this manner, a battery structure can be formed, and the photocatalytic activity of the functional film 3 can be improved.

(specific titanium oxide layer)

The functional film 3 includes a specific titanium oxide layer 5 containing a specific titanium oxide. At least a part of the photocatalyst secondary particles 4 is partially or completely covered with the specific titanium oxide layer 5. By providing the functional film 3 with such a layer structure, the specific titanium oxide layer 5 can effectively suppress the photocatalyst secondary particles 4 from being detached. As a result, the abrasion resistance of the functional film 3 can be further improved.

As the specific titanium oxide, titanium phosphate is preferable. Titanium dioxide phosphate is also itself a photocatalyst activated by visible light. Therefore, since the functional film 3 can exhibit photocatalytic activity by visible light as well, the optical member 1 using titanium phosphate oxide as the specific titanium oxide is preferably used in a space (for example, indoor and in a vehicle) not exposed to direct sunlight.

Titanium oxide phosphate is a compound having a Ti-O-P bond in the molecule. Titanium phosphate oxide is obtained by reacting a titanium halide (e.g., titanium tetrachloride) with a phosphorus source (e.g., phosphoric acid) in an aqueous solvent. The aqueous solvent may be, for example, a mixed solvent containing water and an ethanol compound.

Titanium peroxide is a compound having a Ti-O-Ti bond in the molecule. Titanium peroxide is obtained, for example, by the following method. First, a titanium chloride (e.g., titanium tetrachloride) is reacted with a base compound (e.g., ammonia or sodium hydroxide) in an aqueous solution. Thus, titanium hydroxide Ti (OH) was obtained₄. By treating the titanium hydroxide with hydrogen peroxide water, titanium peroxide can be obtained.

Preferably, the specific titanium oxide is amorphous. By thus making the specific titanium oxide amorphous, the adhesion of the specific titanium oxide layer 5 to the photocatalyst secondary particles 4 and the adhesive layer 6 can be improved. As a result, the abrasion resistance of the functional film 3 can be further improved.

(adhesive layer)

The functional film 3 includes an adhesive layer 6 containing an adhesive. The adhesive layer 6 covers the light-transmissive member 2. At least a part of the secondary photocatalyst particles 4 is partially embedded in the adhesive layer 6. By providing the functional film 3 with such a layer structure, the adhesive layer 6 can effectively suppress the photocatalyst secondary particles 4 from coming off. As a result, the abrasion resistance of the functional film 3 can be further improved.

The adhesive may be any of an inorganic adhesive and an organic adhesive. Examples of the inorganic binder include silicon and silicate. Examples of the organic binder include resins. From the viewpoint of suppressing decomposition of the binder due to the photocatalytic activity, the binder is preferably an inorganic binder, and more preferably silicon or a silicate.

The thickness of the adhesive layer 6 is preferably 5nm to 50nm, more preferably 10nm to 30 nm. By setting the thickness of the adhesive layer 6 to 5nm or more, the photocatalyst secondary particles 4 can be effectively inhibited from coming off. As a result, the abrasion resistance of the functional film 3 can be further improved. By setting the thickness of the adhesive layer 6 to 50nm or less, the photocatalyst secondary particles 4 are easily exposed from the adhesive layer 6. As a result, the photocatalytic activity of the functional film 3 can be further improved.

< modification 1 >

Next, the optical member 11 according to modification 1 of the optical member 1 will be described with reference to fig. 2. The optical member 11 includes a light-transmissive member 12 and a functional film 13 covering the light-transmissive member 12. The light-transmissive member 12 includes a base material 12a and an antireflection film 12b covering the base material 12 a. The functional film 13 covers the antireflection film 12b in the light-transmissive member 12. The functional film 13 includes photocatalyst secondary particles 14, a specific titanium oxide layer 15, and an adhesive layer 16.

The optical member 11 of modification 1 is different from the optical member 1 of fig. 1 only in that the light-transmissive member 12 is not a single member but is constituted by a plurality of members (the base material 12a and the antireflection film 12 b). Therefore, the description overlapping with the optical member 1 is omitted. The light-transmissive member 12 includes the antireflection film 12b, and thus has excellent optical characteristics as compared with the optical member 1 of fig. 1.

(substrate)

The base material 12a has light-transmitting properties. That is, the base material 12a allows light to pass through. The substrate 12a may be either transparent or translucent. The base material 12a contains glass or resin.

(anti-reflection film)

The antireflection film 12b suppresses reflection of light. Specifically, the optical member 11 includes the antireflection film 12b, thereby suppressing reflection of light, which is to enter the light-transmissive member 12 from the surface on the functional film 13 side, on the surface on the functional film 13 side.

The antireflection film 12b may have a one-layer structure or a multilayer structure. The antireflection film 12b contains, for example, a metal or a metal oxide. The antireflection film 12b is, for example, a vapor-deposited film or a spray-coated film.

The thickness of the antireflection film 12b is preferably 200nm to 400 nm. When the thickness of the antireflection film 12b is less than 200nm, a sufficient antireflection effect tends not to be obtained. When the thickness of the antireflection film 12b exceeds 400nm, the productivity of the optical member 1 tends to be lowered.

< modification 2 >

Next, the optical member 21 according to modification 2 of the optical member 1 will be described with reference to fig. 3. The optical member 21 includes a light-transmissive member 22 and a functional film 23 covering the light-transmissive member 22. The functional film 23 contains specific titanium oxide and photocatalyst secondary particles 24. In the functional film 23, the specific titanium oxide forms a specific titanium oxide layer 25. At least a part of the photocatalyst secondary particles 24 is locally embedded in the specific titanium oxide layer 25.

The optical member 21 of modification 2 is different from the optical member 1 of fig. 1 in that it does not include an adhesive layer and the photocatalyst secondary particles 24 do not constitute aggregates. The description of the optical member 21 overlapping with the optical member 1 will be omitted. The optical member 21 does not include an adhesive layer, and therefore, the productivity thereof is superior to that of the optical member 1 of fig. 1.

[ other modifications ]

The optical member according to the first embodiment is described above with reference to the drawings. However, the optical member of the first embodiment is not limited to the optical member 1 of fig. 1, the optical member 11 of fig. 2, and the optical member 21 of fig. 3.

Specifically, the functional film may contain other components as long as it contains the photocatalyst particles, the specific titanium oxide, and the binder. The adhesive may not form an adhesive layer. At least a part of the secondary photocatalyst particles may be completely embedded in the adhesive layer. In addition, all the photocatalyst secondary particles may be partially or completely covered with a specific titanium oxide layer. The functional film may not contain an adhesive. The specific titanium oxide layer may not be formed.

The "no layer formed" of the binder or the specific titanium oxide means that the content of the binder or the specific titanium oxide contained in the functional film is relatively small, and the layer structure of the binder layer or the specific titanium oxide layer is not clearly observed.

< second embodiment: method for manufacturing optical member

A method for manufacturing an optical member according to a second embodiment of the present invention will be described. The method for manufacturing the optical member includes a film forming step of forming a functional film on the light-transmissive member. The functional film contains: photocatalyst particles activated by ultraviolet rays; and a specific titanium oxide which is titanium phosphate or titanium peroxide. At least a part of the photocatalyst particles constitute photocatalyst secondary particles. The method of manufacturing an optical member can easily manufacture the optical member of the first embodiment.

Preferably, the film forming step includes: a first coating step of coating a first coating liquid containing photocatalyst particles on a surface of a light-transmissive member; and a second coating step of further coating a second coating liquid containing titanium dioxide phosphate particles or titanium peroxide particles on the surface of the light-transmissive member after the first coating step. The coated titanium phosphate oxide particles or titanium peroxide particles form a specific titanium oxide layer. In this way, by making the film formation step include the first coating step and the second coating step, at least a part of the secondary photocatalyst particles is partially or completely covered with the specific titanium oxide layer. As a result, the abrasion resistance of the functional film of the optical member to be formed can be further improved.

As a method for applying the first coating liquid and the second coating liquid, wet treatment is preferable. Examples of the wet treatment include a spin coating method, a roll coating method, a bar coating method, a dip coating method, a spray coating method, and a method in which two or more of these methods are combined (for example, a dip spin coating method). As the wet process, a spin coating method, a dip coating method, or a dip spin coating method is preferable.

Preferably, the first coating liquid further contains a binder raw material. Examples of the binder material contained in the coating liquid include a silane compound and silicon particles. Examples of the silane compound include alkoxysilanes, silazanes, and oligomers using these as raw materials (hereinafter,sometimes denoted as silicate oligomers). The alkoxysilane is of the formula "Si (R)¹)_4-X(OR²)_X"is a compound represented by the formula (I). In the general formula, R¹Represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 1 to 10 carbon atoms. R²Represents an alkyl group having 1 to 3 carbon atoms. Preferably R²Represents a methyl group or an ethyl group. In the general formula, X represents an integer of 1 to 4, preferably 4. Examples of the alkoxysilane include tetramethoxysilane and tetraethoxysilane. The raw material of the adhesive is preferably a silane compound, more preferably a silicate oligomer, and still more preferably a silicate oligomer using alkoxysilane as a raw material.

The content ratio of the photocatalyst particles in the first coating liquid is preferably 0.01 mass% to 50 mass%. In the case where the first coating liquid is applied by a spin coating method or a dip spin coating method, the rotation speed is preferably 500rpm to 10000 rpm. The solid content concentration of the first coating liquid is preferably 1.0 mass% to 10 mass%.

Preferably, the first coating liquid and the second coating liquid each further contain a solvent. The solvent is preferably an aqueous solvent. The aqueous solvent contains water and additives. Examples of the additive include an organic acid, an ethanol compound, and ammonia. The content ratio of the additive in the aqueous solvent is preferably more than 0 mass% and 20 mass% or less. As the organic acid, formic acid, acetic acid, acrylic acid, succinic acid, citric acid and malic acid are cited. Examples of the ethanol compound include methanol, ethanol, isopropanol, n-propanol, and butanol.

In the first coating step, the first coating liquid is preferably subjected to a heat treatment after coating. The removal of volatile components in the first coating liquid is promoted by heat treatment. In addition, in the case where the first coating liquid contains a silane compound as a raw material for the binder, a chemical reaction (for example, hydrolytic polycondensation reaction) of the silane compound is promoted by heat treatment. The heating conditions include, for example, a treatment temperature of 60 ℃ to 200 ℃ and a treatment time of 10 minutes to 10 hours.

In the case where the second coating liquid is applied by a spin coating method or a dip spin coating method, the rotation speed is preferably 500rpm to 10000 rpm.

Preferably, the method for producing an optical member further includes a surface treatment step of treating the surface of the light-transmissive member before the film formation step. Examples of the surface treatment include plasma treatment, electron beam treatment, corona treatment, and frame treatment. Examples of the plasma treatment include a high-frequency discharge plasma treatment and an atmospheric pressure glow discharge plasma treatment. These surface treatments may be used in combination of a plurality.

A method for manufacturing an optical member according to a second embodiment will be described below by taking a method for manufacturing the optical member 1 of fig. 1 as an example. The method for manufacturing the optical member 1 includes a film forming step of forming the functional film 3 on the light-transmissive member 2. The functional film 3 contains photocatalyst secondary particles 4, a specific titanium oxide, and a binder. The film forming process includes a first coating process and a second coating process. In the first coating step, a first coating liquid containing photocatalyst particles and a binder raw material is applied to the surface of the light-transmissive member 2. In the drying step, the first coating liquid after coating is dried. In the second coating step, after the first coating step, a second coating liquid containing titanium dioxide phosphate particles or titanium peroxide particles is further applied to the surface of the light-transmissive member 2. Hereinafter, each step will be explained.

(first coating Process)

In this step, a first coating liquid containing photocatalyst particles and a binder material is applied to the surface of the light-transmissive member 2. Through this step, as shown in fig. 4, the adhesive layer 6 is formed from the adhesive material contained in the first coating liquid. The adhesive layer 6 covers the light-transmissive member 2. At least a part of the secondary photocatalyst particles 4 is partially embedded in the adhesive layer 6. The photocatalyst secondary particles 4 constitute aggregates 4 a.

(second coating step)

In this step, a second coating liquid containing titanium dioxide phosphate particles or titanium peroxide particles is further applied to the surface of the light-transmissive member 2. The titanium phosphate particles or the titanium peroxide particles form the specific titanium oxide layer 5 by removing volatile components in the second coating liquid.

At least a part of the photocatalyst secondary particles 4 is partially or completely covered with the specific titanium oxide layer 5. Thereby obtaining the optical member 1. In this step, the second coating liquid is preferably heated after coating. Specific examples of the heating method include the same heating method as described in the first coating step.

Examples

[ example 1]

The optical member of example 1 was manufactured by the following method. The functional film of the optical member of example 1 has a layer structure substantially similar to the functional film 13 of the optical member 11 shown in fig. 2.

(translucent Member)

A lens (TAFD-5G manufactured by HOYA K.K., glass as a component, and having a radius of curvature of a lens surface of 12mm) was prepared as a base material. Then, an antireflection film (composition: SiO) was formed on the lens₂Layer, TiO₂Layer and Ta₂O₅Layers). The total thickness of the antireflection film was about 300 nm. Thereby obtaining a light-transmissive member. Next, the surface of the antireflection film of the light-transmitting member is subjected to surface treatment. As the surface treatment, plasma treatment using a plasma surface modification apparatus was performed.

(first coating liquid)

To 1mL of an aqueous dispersion of titanium oxide particles ("STS-01" manufactured by Shiko K.K., average particle diameter of titanium oxide particles: 7nm, titanium oxide particle concentration: 30% by mass) was added 29mL of isopropyl alcohol to obtain a mixed solution A. A coating agent (ST-K211 manufactured by Shiko corporation, solvent: water and ethanol, solid content concentration: 0.2 mass%) containing titanium oxide particles and a binder raw material (silicate oligomer) was mixed with the mixed solution A at a mass ratio of 1:1 to prepare a first coating solution.

(second coating solution)

5mL of titanium tetrachloride was added to a mixture of 25mL of isopropyl alcohol and 25mL of purified water while stirring to obtain a titanium tetrachloride solution. Purified water (diluted 100 times) was added to the titanium tetrachloride solution to make the volume 100 times, thereby obtaining a titanium tetrachloride diluted solution. A second coating solution was obtained by adding 5mL of an aqueous phosphoric acid solution (phosphoric acid concentration: 85% by mass) to the diluted titanium tetrachloride solution. The second coating liquid contains titanium dioxide phosphate particles.

The first coating liquid is applied to the surface of the antireflection film of the light-transmitting member. The first coating liquid was applied using a spin coater ("MS-B100" manufactured by Chimapo corporation) at a rotation speed of 5000 rpm. After the coating, heat treatment was performed at 80 ℃ for 30 minutes.

After the drying treatment, the second coating liquid is further applied to the surface of the antireflection film of the light-transmissive member. The second coating liquid was applied using a spin coater ("MS-B100" manufactured by Chimapo corporation) at a rotation speed of 5000 rpm. After the coating, heat treatment was performed at 80 ℃ for 30 minutes. Thus, an optical member of example 1 was obtained.

The cross section of the optical member of example 1 was observed by SEM ("JSM-7900F", manufactured by Nippon electronics Co., Ltd.). The adhesive layer of the optical member of example 1 had a thickness of 20nm, the average particle diameter of the secondary photocatalyst particles was 10nm, and the average particle diameter of the aggregates of the secondary photocatalyst particles was 50 nm. Further, the titania phosphate particles contained in the second coating liquid of the optical member of example 1 were bonded to each other to form a porous specific titanium oxide layer.

[ example 2]

An optical member of example 2 was manufactured by the same method as example 1, except that the following points were changed. In the production of the optical member of example 2, a coating liquid prepared by the following method was used as the second coating liquid.

(second coating solution)

Distilled water was added to 1mL of an aqueous titanium tetrachloride solution (concentration: 60% by mass) to adjust the volume to 100mL, thereby obtaining a diluted aqueous titanium tetrachloride solution. To the diluted titanium tetrachloride aqueous solution, 4mL of an aqueous hydrogen peroxide solution (concentration 30% by mass) was added and stirred to obtain a mixed solution. A sodium hydroxide aqueous solution was added to the mixed solution to adjust the pH to 7, thereby obtaining a titanium peroxide hydrate solution containing titanium peroxide hydrate. The obtained titanium peroxide hydrate solution was allowed to stand at 25 ℃ for a whole day and night to form a yellow precipitated precipitate. After the precipitated precipitate was filtered and washed, distilled water was added to adjust the volume to about 30mL, thereby obtaining a reaction solution. The reaction solution was charged with 5g of a cation exchange resin and an anion exchange resin, respectively, and then allowed to stand for 30 minutes. And filtering the reaction solution after standing to remove the cation exchange resin and the anion exchange resin. Distilled water was added to the filtered reaction solution to adjust the volume to about 36mL, and then the reaction solution was cooled. After 4mL of hydrogen peroxide water (concentration: 0.3g/mL) was added to the cooled reaction solution, the reaction solution was further cooled. Thereby, a second coating liquid containing titanium peroxide particles was prepared.

The preparation method of the cation exchange resin and the anion exchange resin is as follows. "Amber light (Japanese: アンバーライト) IR 120B (Na) manufactured by ORGANO K.K. was treated with 2N hydrochloric acid⁺Replacement type) "after 1 hour of treatment, washing was carried out to change it to H⁺Substitution type. It was used as a cation exchange resin. IRA 410 (Cl) was prepared by subjecting "Amber light (Japanese: アンバーライト) manufactured by ORGANO corporation to sodium hydroxide treatment with 1N^-Substitution type) "after 1 hour of treatment, washing was carried out to change it to OH^-Substitution type. It was used as an anion exchange resin.

The cross section of the optical member of example 2 was observed by the SEM. The optical member of example 2 was deposited on the adhesive layer and the photocatalyst secondary particles in a state where the titanium peroxide particles contained in the second coating liquid were moderately dispersed (i.e., in a gel state), thereby forming a specific titanium oxide layer. The points other than the above were the same as the observation results of the optical member of example 1.

Comparative example 1

An optical member of comparative example 1 was produced by the same method as example 1, except that the following points were changed. In the production of the optical member of comparative example 1, the second coating liquid was not applied.

The cross section of the optical member of example comparative example 1 was observed by the SEM. The observation results of the functional film of the optical member of comparative example 1 and the optical member of example 1 were the same except that the specific titanium oxide layer was not present.

< evaluation >

The abrasion resistance of the functional film of each optical member and the photocatalytic activity in the room were evaluated by the following methods. In addition, each measurement was carried out in an environment at a temperature of 23 ℃. + -. 3 ℃ and a relative humidity of 50%. + -. 3%.

[ abrasion resistance ]

Abrasion resistance was measured for each of the optical members of example 1, example 2 and comparative example 1. First, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as the initial contact angle (a). In the measurement of the contact angle, pure water was used as a sample, and an automatic contact angle meter ("DMo-601", manufactured by Kyowa Kagaku K.K.) was used as a measuring device. In the present example, the following contact angles were measured by the automatic contact angle measuring instrument. In this example, the contact angle of the surface of the functional film was judged to be good at 30 degrees or less, more preferably at 20 degrees or less, and particularly preferably at 15 degrees or less.

Next, the surface of the functional film of each optical member is lightly wiped ten times in a reciprocating manner using a paper scraper ("K-dry (japanese: ケイドライ) (registered trademark)") manufactured by japanese paper Crecia corporation (japanese: japanese クレシア). After that, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as a contact angle (B) of the first wiping treatment.

Next, the surface of the functional film of each optical member is irradiated with ultraviolet rays. The ultraviolet irradiation conditions were 352nm in wavelength, 4 hours in irradiation time, and 1mW/cm in irradiance². After that, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as a contact angle (C) of the first ultraviolet irradiation.

Next, the surface of the functional film of each optical member was lightly wiped twenty times in a reciprocating manner using a paper scraper ("K-dry (japanese: ケイドライ) (registered trademark)" manufactured by Crecia corporation of japan (japanese: japan: クレシア). After that, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as a contact angle (D) of the second wiping treatment.

Next, the surface of the functional film of each optical member is irradiated with ultraviolet rays. The ultraviolet irradiation conditions were 352nm in wavelength, 4 hours in irradiation time, and 1mW/cm in irradiance². After that, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as a contact angle (E) of the second ultraviolet irradiation. The measurement results are shown in table 1 and fig. 5 below. In fig. 5, "I" represents example 1, "II" represents example 2, and "III" represents comparative example 1. The same is true for fig. 6.

[ Table 1]

As shown in table 1 and fig. 5, each optical member was subjected to wiping treatment to increase the contact angle of the functional film surface (decrease in hydrophilicity). This is considered to be because a part of the photocatalyst particles was detached from the functional film by the wiping treatment and the organic matter was attached to the surface of the functional film. On the other hand, each optical member exhibits photocatalytic activity by ultraviolet irradiation, and the contact angle of the surface of the functional film decreases (hydrophilicity recovers).

The initial contact angle (a) of the surface of the functional film of each of the optical members of example 1 and example 2 was the same degree as that of the optical member of comparative example 1. From this, it was judged that the functional film had excellent photocatalytic activity. That is, it was confirmed that the specific titanium oxide hardly decreases the photocatalytic activity of the functional film.

In addition, the contact angle (E) of the second ultraviolet irradiation of the surface of the functional film of each of the optical members of examples 1 and 2 was lower (the contact angle was 30 degrees or less) than that of the optical member of comparative example 1. This is because the functional films of the optical members of examples 1 and 2 were excellent in abrasion resistance, and the photocatalytic activity of the functional films was maintained even by the wiping treatment twice. From this, it was found that the abrasion resistance of the functional film can be improved by containing the specific titanium oxide in the functional film.

In addition, the initial contact angle (a) of the surface of the functional film of the optical member of example 1 was the same degree as that of the optical member of example 2, but the contact angle of the surface of the functional film was lower at any stage thereafter. From this, it was found that the titanium phosphate oxide used in example 1 is more effective than the titanium peroxide used in example 2 in order to improve the abrasion resistance of the functional film.

[ photocatalytic Activity in the Room ]

The photocatalyst activity in the chamber was measured for each optical member of example 1 and comparative example 1. The measurements were made indoors (about 300lx) under LED illumination. First, the contact angle of the surface of the functional film of each optical member was measured. The obtained result was taken as the contact angle on day 0.

Next, each optical member was stored for 30 days in a room under LED illumination. Then, the contact angle of the surface of the functional film of each optical member was measured on days 1, 5, 10, 15, 20, 25, and 30. The measurement results are shown in table 2 and fig. 6 below.

[ Table 2]

As shown in table 2 and fig. 6, the contact angle of the surface of the functional film on day 30 of the optical member of example 1 was also 15 degrees or less, and constant hydrophilicity was maintained in the room. On the other hand, the optical member of comparative example 1 had a contact angle of the surface of the functional film of 30 degrees or more on day 30, and did not maintain hydrophilicity in the room. From the above, it was confirmed that the functional film can exhibit photocatalytic activity even in visible light by using titanium phosphate oxide as the specific titanium oxide.

The present invention is preferable as an optical member for a sensor or an imaging device, or a method for manufacturing the same.

(symbol description)

1. 11, 21 optical members;

2. 12, 22 a light-transmissive member;

12a substrate;

12b an antireflection film;

3. 13, 23 functional films;

4. 14, 24 photocatalyst secondary particles;

4a, 14a aggregates;

5. 15, 25 a specific titanium oxide layer;

6. 16, 26 adhesive layers.