JPH11300216A - Photocatalytic hydrophilic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic hydrophilic member in which hydrophilic nature can be maintained for a long period in the environment of ultraviolet rays with low intensity of illumination. SOLUTION: In the photocatalytic hydrophilic member, a surface layer containing a photocatalytic oxide particle, silica and/or silicone, in which at least a part of an organic group bonded to a silicon atom is substituted for a hydroxyl group, is formed on the surface of a substrate. The specific surface area of the photocatalytic oxide particle is <=50 m<2> /g and the surface layer shows superhydrophilicity in accordance with photoexcitation of the photocatalytic oxide particle. Also, hydrophilicity is maintained by irradiation of ultraviolet rays of <=0.001 mw/cm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member improved in order to extend the maintenance period of hydrophilicity in low-illuminance UV irradiation.

[0002]

2. Description of the Related Art JP-A-9-241038 proposes a photocatalytic composition for better exhibiting photocatalytic performance. Its content is high hydrophilicity (refers to a state of exhibiting water wettability of 10 ° or less in contact angle with water) and good antifogging effect by maintaining hydrophilicity, good photodecomposition of contaminants, etc. 0.1mW / cm
^{It is said that} a sufficient ultraviolet illuminance of ² or more and a specific surface area of the photocatalytic oxide particles constituting the photocatalytic composition are increased, preferably 30 m ² / g or more. However, the photocatalytic oxide particles of 60 m ² / g shown in the examples could not maintain hydrophilicity for a long period of time when the amount of ultraviolet light was small, such as in an indoor space.

[0003]

SUMMARY OF THE INVENTION The above-mentioned JP-A-9-24
With the photocatalytic oxide particles of 60 m ² / g shown in the examples of 1038, hydrophilicity could not be maintained for a long period of time when the amount of ultraviolet rays was small such as in an indoor space. In view of the above circumstances, it is an object of the present invention to provide a photocatalytic hydrophilic member that can maintain hydrophilicity for a long time under a low-illuminance ultraviolet environment.

[0004]

Means for Solving the Problems According to the first aspect of the present invention, which has been made to solve the above-mentioned problems, the specific surface area is set to 50.
m ² / g or less of the photocatalytic oxide particles and silica and / or
Alternatively, there is provided a photocatalytic hydrophilic member having a surface layer containing a silicone in which at least a part of an organic group bonded to a silicon atom is substituted with a hydroxyl group. According to the present invention, since the specific surface area of the photocatalytic oxide particles is set to 50 m ² / g or less, the adhesion of dirt such as organic substances can be reduced, and the hydrophilicity can be maintained longer.

[0005]

Embodiments of the present invention will be described below in detail. The superhydrophilicity in the present invention means a state exhibiting water wettability of about 10 ° or less, preferably about 5 ° or less in terms of a contact angle with water. A photocatalytic oxide is a material that emits light (excitation light) having an energy (that is, a shorter wavelength) larger than the energy gap between the conduction electron band and the valence band of an oxide crystal. An oxide capable of generating conduction electrons and holes by electron excitation (photoexcitation). Anatase-type titanium oxide, brookite-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, One or more selected from the group consisting of tungsten trioxide, ferric oxide, and strontium titanate can be used.

Silicones in which at least a part of the organic group bonded to the silicon atom is substituted with a hydroxyl group include hydrolyzable silanes, alkyl silicates, (partial) hydrolysates thereof, hydrolyzates / condensates, etc. Can be used. Here, as the hydrolyzable silane, methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, n-propyltrimethoxysilane, n-propyltrimethoxysilane Ethoxysilane, n-propyltripropoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, isopropyltripropoxysilane, methyltributoxysilane, ethyltributoxysilane, n-propylbutoxysilane, isopropylbutoxysilane, phenyltrimethoxysilane, Phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Cypropyltriethoxysilane,
γ-glycidoxypropyltripropoxysilane, γ-
Methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltripropoxysilane, β- (3,4-
Epoxycyclohexyl) ethyltrimethoxysilane,
β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, trifluoropropyl Hydrolyzable organos such as trimethoxysilane, trifluoropropyltriethoxysilane, phenylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, phenylmethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, etc. Silane, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, dimethoxydiethoxy Tetraalkoxysilanes such as silane can be used. As the alkyl silicate, methyl silicate, ethyl silicate, propyl silicate, butyl silicate and the like can be used.

Other inorganic oxides can be added to the surface layer of the photocatalytic hydrophilic member of the present invention. As inorganic oxides, ceria, zirconia, alumina, amorphous titanium oxide, tin oxide, magnesia, calcia, yttria, manganese oxide, chromia, vanadium oxide, copper oxide, cobalt oxide, nickel oxide, ruthenium oxide, hafnia, strontium oxide, One or two or more selected from the group of silver oxides may be mentioned. These inorganic oxides improve the strength of the coating as a filler. Further, when zirconia is added, the water resistance is improved. Also alumina, ceria,
Addition of yttria improves the hydrophilicity in a dark place. The addition of ruthenium oxide or copper oxide improves the redox power. The addition of silver oxide or copper oxide improves antibacterial properties.

[0008] The surface layer of the photocatalytic hydrophilic member of the present invention includes silver, copper, palladium, platinum, rhodium, platinum, ruthenium, gold, zinc, cobalt, iron, nickel,
One or more selected from the group consisting of sodium, lithium, strontium, potassium, calcium, magnesium and compounds of these metals may be added. Antibacterial properties can be imparted by adding at least one selected from the group consisting of silver, copper, zinc and compounds of these metals. By adding at least one selected from the group consisting of palladium, platinum, rhodium, platinum, ruthenium, gold, cobalt, iron, nickel or a compound of these metals, it is possible to improve the oxidation-reduction catalytic performance of the optical semiconductor by photoexcitation. it can. By adding at least one selected from the group consisting of sodium, lithium, strontium, potassium, calcium, magnesium and a compound of these metals, the hydrophilicity of the optical semiconductor according to photoexcitation can be improved.

As a method for forming the photocatalytic hydrophilic member of the present invention, for example, a coating solution in which photocatalytic titanium oxide particles are dispersed is prepared, and the coating solution is spray-coated on a substrate surface, a dip coating method, or the like. Coating method, flow coating method, spin coating method, roll coating method,
The composition is applied by a bar coating method, brush coating, sponge coating, or the like, and is polymerized by heat treatment, standing at room temperature, ultraviolet irradiation, or the like to fix the surface layer to the substrate. When a coating film is formed on the surface of the member by the above method, the surface of the member becomes hydrophilic in response to the photoexcitation of the photocatalyst. Here, by photoexcitation of the photocatalyst,
In order for the surface of the base material to be highly hydrophilic, the illuminance of the excitation light may be 0.001 mW / cm ² or more.
It is preferably at least mW / cm ^2, more preferably at least 0.1 mW / cm ² . When the photocatalytic oxide is an anatase type titanium oxide, a rutile type titanium oxide, a zinc oxide, or a strontium titanate, the light source used for photoexcitation of the photocatalyst is sunlight, indoor lighting, fluorescent lamp, mercury lamp, incandescent lamp. Electric lamps, xenon lamps, high-pressure sodium lamps, metal halide lamps, BLB lamps and the like can be suitably used. When the photocatalytic oxide is tin oxide, a germicidal lamp, BL
A B lamp or the like can be suitably used.

If the surface of the photocatalytic hydrophilic member maintains a contact angle with water of 10 ° or less, preferably 5 ° or less, the following antifogging effect is exhibited. Even if moisture or steam in the air is dewed, the tendency of condensed water to form a uniform water film without forming individual water droplets becomes remarkable. Therefore,
The tendency that the surface does not have light scattering fogging 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.

If the surface of the photocatalytic hydrophilic member maintains a contact angle with water of 30 ° or less, preferably 20 ° or less, the following surface cleaning effects are exhibited. Combustion products such as carbon black and the like contained in urban exhaust dust and automobile exhaust gas, hydrophobic contaminants such as oils and fats, sealant eluting components, and inorganic clay contaminants are hardly adhered to each other. However, it can be easily dropped by rain or washing. If the surface of the photocatalytic hydrophilic member exhibits the above-mentioned high hydrophilicity and maintains the state, the antistatic effect (dust adhesion preventing effect), heat insulation effect, bubble adhesion preventing effect in water, heat exchanger In this case, the effect of improving efficiency, the effect of improving biocompatibility, etc. are exhibited.

The substrate to which the photocatalytic hydrophilic member of the present invention can be applied is a transparent substrate when antifogging effect is expected, and glass, plastic or the like can be suitably used as the material. Speaking of applicable base materials, there are mirrors such as rearview mirrors for vehicles, bathroom mirrors, toilet mirrors, dental mirrors, road mirrors; spectacle lenses, optical lenses, illumination lenses,
Lenses such as semiconductor lenses, copier lenses, rear view camera lenses for vehicles; prisms; windows of buildings and towers; automobiles, railway vehicles, aircraft, ships, submersibles, snowmobiles, lowway gondola. Vehicle windows, such as amusement park gondolas, spaceships; vehicles, motorbikes, rail cars, aircraft, ships, submarines, snowmobiles, snowmobiles, lowway gondolas, amusement parks Windshields for vehicles such as gondola and spacecraft; protective goggles, sports
Goggles for shoes, shields for protective masks, shields for sports masks, shields for helmets, glass for frozen food display cases, display cases for warm foods such as Chinese buns Glass; cover of measuring instrument, cover of camera lens for rear view confirmation, cover lens of laser, dental treatment device, etc., cover of laser light detecting sensor, such as inter-vehicle distance sensor,
Cover of infrared sensor; filter for camera, and film, sheet, or sheet for attaching to the surface of the article
Includes

As a substrate to which the photocatalytic hydrophilic member of the present invention can be applied, when a surface cleaning 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.
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 girder rails, interior and coating of tunnels, insulators, solar cell covers, solar water heater collectors, vinyl houses , Vehicle lighting covers, housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchenware, dishes, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods, ventilation fans And a film, a sheet, a seal, and the like for sticking to the surface of the article.

As a substrate to which the photocatalytic hydrophilic member of the present invention can be applied, when a drying promoting effect is expected, its material is, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, or the like. -Fibers, fabrics, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable base materials, films, sheets, and the like to be adhered to automobile bodies, windows, pavements and the surface of the above-mentioned articles.
Including seals and the like.

As a substrate to which the photocatalytic hydrophilic member of the present invention can be applied, when an antistatic effect is expected, the material is, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, or the like. -Fibers, fabrics, 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.

[0016]

Example 1 Performance of maintaining hydrophilicity in ultraviolet light irradiation in dark place and low illuminance (1) Preparation of example sample Titania sol (STS-01 manufactured by Ishihara Sangyo, solute concentration 30)
wt%, crystal particle diameter 7 nm, specific surface area 50 m ² / g)
6.67 g and 2.39 g of methyl silicate (Toshiba Silicone Tosgard 510, solute concentration 21%) were mixed,
5: 5 diacetone alcohol and normal propanol
After diluting with 74.2 g of the mixed solution, stirring was performed to prepare a photocatalyst solution 1. The prepared photocatalyst solution 1 was applied to a slide glass using a bar coating method, dried at room temperature for 30 minutes, and then dried in a thermostat ADP-31 (manufactured by Yamato Chemical).
Drying was performed at 30 ° C. for 30 minutes to prepare a # 1 sample of Example 1.

(2) Preparation of Comparative Example Sample Titania sol (STS-21 manufactured by Ishihara Sangyo, solute concentration: 40)
wt%, crystal particles 20 nm, specific surface area 300 m ² / g)
, A # 2 sample of the comparative example was prepared in the same manner as described in (1) Preparation of sample above.

(3) Evaluation of hydrophilicity retention in dark place The # 1 sample of Example 1 and the # 2 sample of Comparative Example were irradiated with a ² mW / cm ² BLB lamp for 185 hours.
Hydrophilization was applied. Then, it was stored in a dark place with air circulation, and the change in the contact angle of water with the lapse of time was investigated. FIG. 1 shows the evaluation results. As shown in FIG. 1, Sample 1 having a small specific surface area of the photocatalytic oxide particles has a sufficient water contact angle of 5 ° or less in a long term of about one month as compared with the comparative sample having a large specific surface area of the photocatalytic oxide particles. It was confirmed that the hydrophilicity was maintained.

(4) Hydrophilicity maintenance performance in UV irradiation at low illuminance The # 1 sample of Example 1 and the # 2 sample of Comparative Test Example were irradiated with a ² mW / cm ² BLB lamp for 185 hours to make them hydrophilic. gave. Then, use a white fluorescent lamp for 0.00
Irradiation with ultraviolet light of 1 mW / cm ² was conducted to investigate the change in the contact angle of water with respect to the irradiation time. FIG. 2 shows the evaluation results. As shown in FIG. 2, Sample 1 having a small specific surface area of the photocatalytic oxide particles has a sufficient water contact angle of about 6 ° in a long term of about one month as compared with the comparative sample having a large specific surface area of the photocatalytic oxide particles. It was found to maintain hydrophilicity. In an environment where a large amount of ultraviolet rays cannot be expected, such as an indoor space, as shown in FIGS. 1 and 2, the smaller the specific surface area is, the higher the load due to the adhesion of dirt due to organic substances is than the optical resolution by ultraviolet irradiation. It was confirmed that the adhesion of the photocatalytic hydrophilic member can be expected to be prolonged, and the anti-fogging effect by maintaining the hydrophilic property can be expected.

[0020]

By using the photocatalytic oxide particles having a specific surface area of 50 m ² / g or less according to the present invention, the adhesion of dirt such as organic substances can be reduced, so that the hydrophilicity retention in a low illuminance ultraviolet environment is prolonged. Thus, a photocatalytic hydrophilic member having a surface layer that can lengthen the period until regeneration can be produced.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the number of days of storage in a dark place and the contact angle of water on the surface of the sample after the sample according to the embodiment of the present invention is superhydrophilized and stored in a dark place.

FIG. 2 is a diagram showing the relationship between the number of irradiation days and the contact angle of water on the surface of a sample after the sample according to the example of the present invention is made superhydrophilic and then irradiated with ultraviolet light at a constant illuminance.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C09K 3/18 C09K 3/18

Claims (2)

[Claims] 1. A photocatalytic hydrophilic material having a surface layer containing a photocatalytic oxide particle and a silicone in which at least a part of an organic group bonded to silica and / or a silicon atom is substituted with a hydroxyl group on the surface of a substrate. The specific surface area of the photocatalytic oxide particles is 50 m ² / g or less;
A photocatalytic hydrophilic member, wherein the surface layer exhibits superhydrophilicity in response to photoexcitation of the photocatalytic oxide particles, and maintains hydrophilicity by irradiation with ultraviolet rays of 0.001 mw / cm ² or less. 2. The photocatalytic hydrophilic member according to claim 1, wherein the hydrophilicity is such that the contact angle with water on the surface of the photocatalytic hydrophilic member is 10 ° or less and is maintained for 40 days or more. .