JP3109457B2 - Photocatalytic hydrophilic member and photocatalytic hydrophilic coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalytic hydrophilic member capable of rendering a member surface hydrophilic by irradiating weak near-ultraviolet rays included in indoor lighting, and a photocatalytic hydrophilic surface by coating a substrate. Photocatalytic hydrophilic core capable of forming
Ting composition.

[0002]

2. Description of the Related Art The present inventor has previously proposed a method for highly hydrophilizing the surface of an article by photoexcitation of a semiconductor photocatalyst (WO 96/29375). According to this method,
The surface of the article is coated with a coating of a semiconductor photocatalyst such as an anatase type titanium oxide. This you
When the photocatalytic coating made of titanium oxide is irradiated with ultraviolet light to excite the photocatalyst with sufficient illuminance for a sufficient time, the surface of the photocatalytic coating has a contact angle with water of about 0 degrees. Highly hydrophilized. As disclosed in WO 96/29375,
The photocatalytic coating which can be highly hydrophilized as described above can be applied to various articles for various purposes such as anti-fogging, purification by rainfall, purification by washing, promotion of drying, and the like. For example, when a transparent article such as a windshield of a vehicle, a door mirror, a window glass of a building, a lens of an eyeglass, or a mirror is coated with a photocatalytic coating, the surface of the coating is caused by the photoexcitation of the photocatalyst. It is highly hydrophilized, so that the article is prevented from fogging with condensed moisture or steam and from being overshadowed by adhering water droplets. Alternatively, if a building or an article placed outdoors is covered with a photocatalytic coating, lipophilic or hydrophobic dust and contaminants attached to the hydrophilic surface are washed away by rainwater each time it rains. And the surface is purified. Further, as disclosed in WO96 / 29375, in addition to the photocatalyst, a silicone in which at least a part of an organic group bonded to silica or a silicon atom is substituted with a hydroxyl group is added to the surface layer. In this case, the surface is maintained hydrophilic even if it is left in a dark place for a while after being made superhydrophilic by photoexcitation of the photocatalyst.

[0003]

However, if the surface layer is added with a silicone in which at least a part of the organic group bonded to the silica or silicon atom is substituted by a hydroxyl group, the excitation wavelength of the photocatalyst is short. Shift to the side. As a result, for example, when anatase-type titanium oxide is used as a photocatalyst, 350 nm to 390 n, which is included in a large amount of light emitted from indoor lighting such as a fluorescent lamp among the excitation light rays, is used.
m, it is difficult to be excited by near-ultraviolet light, and there is a problem that the hydrophilicity by photoexcitation of the photocatalyst does not progress sufficiently under room illumination. Therefore, in the present invention, 350 nm to 390, which are included in a large amount of light emitted from indoor lighting such as a fluorescent lamp, are used.
It is an object of the present invention to provide a photocatalytic hydrophilic member having hydrophilicity in a dark place, which can make the surface of the member hydrophilic by irradiation with near-ultraviolet light of nm.

[0004]

According to the present invention, in order to solve the above-mentioned problems, photocatalyst particles, silica and / or
Or silicon and Cr, Ru, Co, Ce, Rh, V
Or a layer containing at least one substance selected from the group of compounds is formed, and the surface of the member becomes hydrophilic in response to photoexcitation of the photocatalyst, wherein the photocatalytic hydrophilic member is provided. And a photocatalyst particle, a precursor for forming a silica film and / or a fine particle silica for forming a silicone film, and Cr, R
and at least one substance selected from the group consisting of u, Co, Ce, Rh, V and compounds thereof. Cr, Ru, C
1 selected from the group consisting of o, Ce, Rh, V or a compound thereof
By adding more than one substance, silica and / or silica
The shift of the excitation wavelength of the photocatalyst to the shorter wavelength side due to radiation is suppressed, and the surface of the member exhibits a high degree of hydrophilicity due to irradiation of near ultraviolet rays of 350 nm to 390 nm which are included in a large amount of light emitted from indoor lighting such as a fluorescent lamp. Become like

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a photocatalyst is irradiated with light (excitation light) having an energy (that is, a short wavelength) larger than the energy gap between the conduction band and the valence band of the crystal. Sometimes, a substance capable of generating conduction electrons and holes by excitation of electrons (photoexcitation) in a valence band. Photocatalytic oxides include, for example, anatase type titanium oxide and rutile type oxide. Oxides such as titanium, zinc oxide, ferric oxide, bismuth trioxide, tungsten trioxide, and strontium titanate can be suitably used. The high hydrophilicity in the present invention means a state exhibiting water wettability of 10 ° or less, preferably 5 ° or less in terms of a contact angle with water.

As a precursor for forming a silica coating, an average composition formula SiX _q O _{(4-q) / 2} (where X is an alkoxy group or a halogen atom, and q is 0 <q < A silicate represented by the general formula SiX4 (where R is a functional group comprising one or more monovalent organic groups, or a monovalent organic group) And X is a functional group composed of two or more selected from hydrogen groups, and X is an alkoxy group or a halogen atom. Available. Here, the tetrafunctional hydrolyzable silane derivative includes tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane,
Diethoxydimethoxysilane and the like can be suitably used. The silicate can be prepared by partial hydrolysis, dehydration-condensation polymerization or the like of the tetrafunctional hydrolyzable silane derivative.

As a precursor for forming a silicon film, an average composition formula R _p SiO _{(4-p) / 2} (where R is one or more monovalent organic groups) A functional group or a functional group composed of two or more selected from a monovalent organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p is a number satisfying 0 <p <2. Or a liquid polymer or oligomer represented by the general formula RpSi
X _4-p (wherein, R is a functional group composed of one or more monovalent organic groups, or a functional group composed of two or more monovalent organic groups and hydrogen groups. , X is an alkoxy group or a halogen atom, and p is 1 or 2). Here, as the hydrolyzable silane derivative, methyltrimethoxysilane, methyltriethoxysilane,
Methyl tripropoxy silane, methyl tributoxy silane, ethyl trimethoxy silane, ethyl triethoxy silane, ethyl tripropoxy silane, ethyl tributoxy silane, phenyl trimethoxy silane, phenyl triethoxy silane, phenyl tripropoxy silane, phenyl tributoxy silane, Dimethyldimethoxysilane,
Dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane,
Phenylmethyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n
-Propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-
Glycodoxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane and the like can be suitably used. Examples of the siloxane polymer or oligomer include partial hydrolysis and dehydration condensation polymerization of the hydrolyzable silane derivative, or partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, tetrapropoxy, and the like. It can be produced by dehydration-condensation polymerization with a partial hydrolyzate such as silane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

As the fine particle silica, an average particle diameter of 1 to 10
0 nm, preferably 5 to 50 nm, more preferably 8 to
20 nm silica particles are available.

Examples of the substance that suppresses the shift of the excitation wavelength of the photocatalyst to the shorter wavelength side by the silica or the silicon include metals such as Cr, Ru, Co, Ce, Rh, and V, oxides thereof, and chlorides. Substances, hydroxides, sulfate compounds, nitrate compounds and the like can be suitably used.

The coating composition includes Ag, Cu, Z
A metal such as n can be added. When the metal is added, the surface layer formed by the coating film can kill bacteria and fungi attached to the surface even in a dark place.

[0011] The coating composition includes Pt, Pd, R
A platinum group metal such as u, Rh, Ir, Os can be added. When the metal is added, the surface layer formed by the coating film can enhance the oxidation-reduction activity of the photocatalyst, and can improve the decomposability of organic contaminants and harmful gases and odors.

The coating composition also promotes hydrolysis of solvents such as water, ethanol and isopropanol, and precursors of silicones such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid and maleic acid. Catalysts for curing precursors of silicones such as catalysts, basic compounds such as tributylamine and hexylamine, and acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate; silane coupling agents And a leveling agent such as diacetone alcohol and cellosolve, etc. for improving the dispersibility of the coating liquid.

The method of using the coating composition of the present invention is basically based on applying the coating composition on the surface of a substrate and curing the coating composition to form a coating film.

The coating composition may be applied by spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, sponge coating, or the like. A method such as coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

When a coating film is formed on the member surface by the above method,
The surface of the member becomes hydrophilic in response to the photoexcitation of the photocatalyst. Here, in order for the substrate surface to be highly hydrophilized by photoexcitation of the photocatalyst, the illuminance of the excitation light must be 0.001.
mW suffices / cm ² or more, but preferably that it 0.01 mW / cm ² or more, and more preferably it 0.1 mW / cm ² or more. When the photocatalytic oxide is an anatase type titanium oxide, a rutile type titanium oxide, a zinc oxide, or a strontium titanate, as a light source used for photoexcitation of the photocatalyst,
Sunlight, indoor lighting, fluorescent lamps, mercury lamps, incandescent lamps, xenon lamps, high-pressure sodium lamps, metal halide lamps, BLB lamps and the like can be suitably used.

The thickness of the surface layer formed by a coating film on the member surface is preferably 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. Furthermore, the thickness of the surface layer is
It is more preferable that the thickness be 0.2 μm or less. Then, it is possible to prevent the surface layer from being colored by light interference. Also, the thinner the surface layer, the better its transparency.
Further, when the film thickness is reduced, the wear resistance of the surface layer is improved.

As shown in PCT / WO96 / 29375, if the surface of the member is not more than 10 ° in terms of the contact angle with water, even if moisture or steam in the air is condensed, it will not condense. Water tends to form a uniform water film without forming individual water droplets. Therefore, the tendency that light scattering fogging does not occur on the surface becomes remarkable. Similarly, when a window glass, a vehicle back mirror, a vehicle windshield, an eyeglass lens, or a shield of a helmet is exposed to rainfall or splashing, discrete unsightly water droplets are not formed, and high visibility and visibility are achieved. As a result, the effects of ensuring vehicle safety, ensuring the safety of vehicles and traffic, and improving the efficiency of various tasks and activities are dramatically improved. Similarly, as shown in PCT / WO96 / 29375, if the surface of the member is 10 ° or less, preferably 5 ° or less in terms of the contact angle with water, the exhaust of city dust, automobiles, etc. Combustion products such as carbon black contained in gas, hydrophobic contaminants such as oils and fats, sealant eluting components, etc., and inorganic clay contaminants are unlikely to adhere, and even if adhered, it is easy to rain and wash. Can be dropped.

If the surface of the member exhibits the above-mentioned high hydrophilicity and maintains the state, the anti-fogging effect, the surface cleaning effect, the antistatic effect (dust adhesion preventing effect), the heat insulating effect, The effect of preventing bubbles from adhering in water, the effect of improving efficiency in a heat exchanger, the effect of improving biocompatibility, and the like are exhibited.

The substrate to which the present invention can be applied is a transparent member when an anti-fogging effect is expected, and glass, plastic, and the like can be suitably used as the material. Speaking of applicable base materials, mirrors such as rearview mirrors for vehicles, mirrors for bathrooms, mirrors for toilets, dental mirrors, road mirrors; spectacle lenses, optical lenses, illumination lenses, semiconductor lenses Lenses such as copier lenses, rear view camera lenses for vehicles; prisms; windows of buildings and towers; automobiles, railway vehicles, aircraft, ships, submersibles, snowmobiles, lowway gondola, amusement parks Gondolas, vehicle windows such as spaceships; cars, motorbikes, railway vehicles, aircraft, ships, submersibles, snowmobiles, snowmobiles, lowway gondola, amusement park gondola, space Windshield for vehicles such as ships; protective goggles, sports goggles, protective mask shield, sports mask shield, helmet shield, frozen food display Case glass, Chinese bun, etc. Glass for display case of warm food; Cover for measuring equipment, Cover for rear view camera lens for vehicle, Focusing lens for laser dental treatment device, etc., Laser light detection for inter-vehicle distance sensor, etc. Cover for an infrared sensor, a cover for an infrared sensor, a filter for a camera, and a film, a sheet, a seal, and the like to be attached to the surface of the article.

When a surface cleaning effect is expected as a substrate to which the present invention can be applied, the material may be, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, fiber, or the like. Fabrics, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable base materials, building materials, building exteriors, building interiors, window frames, windowpanes, structural members, vehicle exteriors and coatings, machinery and articles exteriors, dustproof covers and coatings, traffic signs, Various display devices,
Advertising towers, noise barriers for roads, noise barriers for railways, bridges, exterior and coating of garages, tunnel interiors and coatings, insulators, solar battery covers, solar water heater collector covers, vinyl houses, vehicle lighting Light covers, housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchen utensils, dishes, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods
And a film, a sheet, a seal, and the like for attaching to the surface of the article.

As a substrate to which the present invention can be applied, when a drying acceleration effect is expected, its material is, for example, metal,
Ceramic, glass, plastic, wood, stone, cement, concrete, fiber, fabric, combinations thereof, and laminates thereof can be suitably used. Examples of applicable substrates include automobile bodies, windows, pavements, and films, sheets, seals, and the like to be adhered to the surface of the article.

When the antistatic effect is expected as a substrate to which the present invention can be applied, the material is, for example, metal,
Ceramic, glass, plastic, wood, stone, cement, concrete, fiber, fabric, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable substrates, cathode ray tubes, magnetic recording media, optical recording media, magneto-optical recording media, audio tapes, video tapes, analog records, housings and parts for household electrical appliances, Exterior and painting, OA equipment product housing and parts and exterior and painting, building materials, building exterior, building interior, window frames, window glass, structural members, vehicle exterior and painting, mechanical equipment and articles exterior, dustproof cover and Includes films, sheets, seals, etc. for painting and sticking to the surface of the article.

[0023]

【Example】

Embodiment 1 FIG. On a soda lime glass substrate, a photocatalyst coating solution STK-01 (8 parts by weight of titanium oxide particles, 2 parts by weight of alkyl silicate, and an aqueous solution of nitric acid) were used.
8 parts by weight, 28 parts by weight of methanol and 7.2 parts of propanol
A liquid material obtained by diluting (a composition consisting of parts by weight) three times with ethanol was applied by a flow coating method to obtain a plurality of # 1 samples. Further, # 1 sample was treated with 20% chromium oxide.
Immersed in a liquid obtained by dissolving 0.25% by weight in an aqueous ammonia solution at 0.25% by weight, and chromium oxide was coated on the surface of the # 1 sample by a dip coating method in which the sample was pulled up at a pulling rate of 24 cm / min to obtain a # 2 sample. . Next, a light source (Sankyo Electric, Black Light Blue (BLB fluorescent lamp)) with an ultraviolet illuminance of 1 mW / cm ² was applied to the # 2 sample surface, and the center wavelength was 360 n.
m) was irradiated for 1 minute to reduce chromium to obtain a # 3 sample. Next, the # 3 sample was fired by holding it at 500 degrees for 30 minutes to fix the surface layer, and then left in a dark place for 2 weeks to obtain a #A working sample. Also, the above # 1 sample was
Ruthenium chloride was immersed in a liquid obtained by dissolving 0.207% by weight of ruthenium chloride hydrate in water, and then the ruthenium chloride was coated on the surface of # 1 sample by dip-coating by pulling up at a pulling rate of 24 cm / min. A sample was obtained. Then
The sample # 4 was calcined by holding it at 500 ° C. for 30 minutes to fix the surface layer, and then allowed to stand in a dark place for 2 weeks.
A working sample was obtained. On the other hand, the above # 1 sample was
After baking by holding for 0 minute to fix the surface layer, the sample was left in a dark place for 2 weeks to obtain a #C comparative sample. First,
#A to #C Irradiate the sample surface with a light source of ultraviolet illuminance 0.1 mW / cm ² (Sankyo Electric, Black Light Bull (BLB fluorescent lamp), center wavelength 360 nm), and change in contact angle with water with irradiation time Was examined. Here, the contact angle with water was examined by using a contact angle measuring device (Kyowa Interface Science, CA-X150) and measuring it 30 seconds after dropping a water droplet from the micro syringe onto the sample surface. The results are shown in FIG. From the figure, it was confirmed that the #A and #B samples hydrophilized more quickly than the #C sample. Next, #A to #C
From the position 33 cm away from the sample surface, 1
8W indoor fluorescent lamp (Toshiba, Watt Brighter-White, F
L20SS.W / 18), and the change of the contact angle with water with respect to the irradiation time was examined. The results are shown in FIG. From the figure, it was confirmed that the #A and #B samples hydrophilized more quickly than the #C sample.

[0024]

According to the present invention, the surface of a member can be made superhydrophilic in response to photoexcitation of a photocatalyst by irradiating weak near-ultraviolet light emitted from indoor lighting such as a fluorescent lamp. A photocatalytic hydrophilic member can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the time dependence of hydrophilization of a surface in response to photoexcitation of a photocatalyst by irradiation with a BLB fluorescent lamp according to an embodiment of the present invention.

FIG. 2 is a diagram showing the time dependence of hydrophilization of a surface in response to photoexcitation of a photocatalyst by irradiation of a fluorescent lamp for indoor lighting according to an example of the present invention.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C09D 183/02 C09D 183/04 C09K 3/18 C08J 7/04 A47G 1/00 C03C 17 / 23 F21M 7/00 G02B 1/10 EPAT (QUESTEL) WPI / L (QUESTEL)

Claims (7)

(57) [Claims] 1. A layer containing photocatalyst particles, silica, and at least one substance selected from the group consisting of Cr , Co, Ce, V and compounds thereof is formed on a surface of a substrate, and photoexcitation of the photocatalyst is performed. A photocatalytic hydrophilic member, wherein the surface of the member becomes hydrophilic depending on the condition. 2. A layer comprising photocatalyst particles, silicone, and at least one substance selected from the group consisting of Cr , Co, Ce, V and compounds thereof is formed on the surface of the substrate, and photoexcitation of the photocatalyst is performed. A photocatalytic hydrophilic member, wherein the surface of the member becomes hydrophilic depending on the condition. 3. The photocatalyst according to claim 1, wherein the surface of the member exhibits hydrophilicity of 10 degrees or less in terms of a contact angle with water in response to photoexcitation of the photocatalyst. Hydrophilic member. 4. The photocatalyst according to claim 1, wherein the surface of the member has a hydrophilicity of 5 degrees or less in terms of a contact angle with water according to photoexcitation of the photocatalyst. Hydrophilic member. 5. Photocatalytic properties comprising photocatalyst particles, a precursor for forming a silica coating, and one or more substances selected from the group consisting of Cr , Co, Ce, V and compounds thereof. Hydrophilic coating composition. 6. A photocatalytic property comprising photocatalyst particles, a precursor for forming a silicone film, and one or more substances selected from the group consisting of Cr , Co, Ce, V, and compounds thereof. Hydrophilic coating composition. 7. Photocatalyst particles, fine particle silica, Cr ,
A photocatalytic hydrophilic coating composition comprising Co, Ce, V or one or more substances selected from the group of compounds thereof.