WO2001021722A1

WO2001021722A1 - Photocatalytic hydrophilic coating material

Info

Publication number: WO2001021722A1
Application number: PCT/JP2000/006472
Authority: WO
Inventors: Masahiro Yamamoto; Minoru Takashio; Shigeru Kubozono; Junji Hiraoka; Kazuo Hirano; Mikio Horimoto
Original assignee: Toto Ltd.
Priority date: 1999-09-21
Filing date: 2000-09-21
Publication date: 2001-03-29
Also published as: AU7318800A; JP2001089706A

Abstract

A photocatalytic hydrophilic coating material which can be easily applied in situ to a surface of a member to impart a high degree of hydrophilicity while attaining high transparency and which maintains the hydrophilicity. The coating material comprises water, a photocatalytic metal oxide (A), an alkyl silicate (B), and an alkali silicate (C). The proportion of the ingredient (A) to the ingredient (B) on a solid basis is that the TiO2/SiO2 ratio is from 2/8 to 8/2. The content of the alkali silicate is 10 to 40 wt.% based on all the solid ingredients.

Description

Description Photocatalytic hydrophilic coating agent

The present invention relates to a photocatalytic hydrophilic coating agent that easily makes and maintains the surface of a member highly hydrophilic in the field. More specifically, the present invention provides a photocatalytic hydrophilic coating capable of preventing clouding and water droplet formation of members by making the surfaces of mirrors, lenses, glass, prisms and other transparent members highly hydrophilic while maintaining high transparency. The present invention relates to a coating agent that forms The present invention also prevents the surface from being soiled or makes the surface self-cleaning (self-cleaning) by highly hydrophilizing the surface of a building, a window glass, a mechanical device, or an article with high transparency. Alternatively, the present invention relates to a coating agent that forms a photocatalytic hydrophilic film that can be easily cleaned. Background art

It is well known that irradiating a photocatalyst with an excitation light source generates active oxygen species such as hydroxyl radicals and superoxide ions, and based on this, produces redox effects such as oxidative decomposition of organic substances and reduction of metal ions. (For example, JP-A-60-18732 and JP-A-60-155678).

Furthermore, it has been proposed that when a photocatalytic hydrophilic coating is irradiated with an excitation light source, the coating surface becomes hydrophilic accordingly (PCT / W096 / 293375).

Also, by forming a layer containing a photocatalytic titanium oxide and an amorphous oxide on the surface of the base material, the surface can be permanently maintained at a high degree of hydrophilicity, and the hydrophilicity can be improved even in light shielding. It has also been proposed that it can be maintained to some extent (Japanese Patent Application Laid-Open No. 9-1222710).

However, a photocatalytic coating agent capable of easily forming a highly transparent photocatalytic hydrophilic film on a target substrate to be made hydrophilic has not been developed.

The present invention makes it possible to easily make the surface of a member highly hydrophilic while maintaining high transparency on site, The development of a photocatalytic hydrophilic coating agent to be maintained.

The present inventors have conducted intensive studies to solve the above problems, and as a result, have developed a photocatalytic hydrophilic coating agent that easily makes the surface of a member highly transparent while maintaining high transparency in the field. Disclosure of the invention

The present invention provides a photocatalytic hydrophilic coating agent that easily makes a member surface highly transparent while maintaining high transparency while maintaining the photocatalytic hydrophilic coating agent, wherein the photocatalytic hydrophilic coating agent is water and a photocatalytic metal. It contains oxide (A), alkyl silicate (B) and alkali silicate (C), and the solid content ratio of photocatalytic metal oxide (A) and alkyl silicate (B) is T i〇 ₂ / S i 0 ₂ = 2 Z 8 to 8 Z 2, characterized in that the alkali metal silicate is contained in an amount of 10 to 40% by weight based on the total solid content of 100% by weight.

When the photocatalytic hydrophilic coating agent requires transparency, the total solid content is 1

It is preferable that the alkali metal silicate is 100 to 20% by weight of the 100% by weight.

The photocatalytic hydrophilic coating agent of the present invention may contain alcohols (D) for improving repelling properties and preventing freezing.

The photocatalytic hydrophilic coating agent of the present invention may contain a surfactant (E) for improving repelling properties and increasing viscosity.

The photocatalytic hydrophilic coating agent of the present invention may contain a polymer thickener (F) for increasing the viscosity.

The photocatalytic hydrophilic coating agent of the present invention may contain a preservative / antifungal agent (G) for preservative / antifungal purposes. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows the time of the contact angle with water on the surface of the photocatalytic hydrophilic film prepared by applying the photocatalytic hydrophilic coating agents # 1 to 4 and Comparative Examples 1 and 2 to the glass surface. It is the graph which investigated change. BEST MODE FOR CARRYING OUT THE INVENTION

The photocatalytic metal oxide (A) in the present invention includes anatase-type titanium oxide, brookite-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, tungsten trioxide, ferric oxide, and titanium. One or more selected from the group of strontium acid can be used.

The average crystallite diameter of the photocatalyst particles is preferably 100 nm or less. The upper limit is preferably about 50 nm or less, and more preferably about 20 nm or less. The lower limit is preferably about 1 nm or more. When the average crystallite diameter of the photocatalyst particles is in the above range, the hydrophilicity can be sufficiently exerted, and the surface to which the composition is applied can be prevented from losing transparency due to scattering of visible light by the particles. . The average crystallite diameter of the photocatalyst particles can be determined from the integral width of the strongest peak in the vicinity of 2θ = 25.3 ° in powder X-ray diffraction of the particles by the Scheerrerr equation. As the photocatalytic metal oxide (A), titania is particularly preferable, and among them, neutral or alkaline titania sol is particularly preferable. Among them, a titania sol to which an alkyl silicate is added is particularly preferable. In the case of neutral, a titania sol whose surface is coated with silica is preferable for preventing aggregation and improving dispersion stability. Acidic titania sol is not suitable for use because it causes coagulation and precipitation when mixed with alkali silicate.

As the alkyl silicate (B), tetraalkoxysilanes such as tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane and tetrabutoxysilane are preferable. Photocatalytic metal oxide (A) and the alkyl silicate solids ratio of the gate (B) is _{_{Ti0 2 / Si0 2 = 2/}} 8 - 8/2 is preferred. For the case of emphasizing transparency is required Arukirushirike one Bok as a binder (B) is more than a certain percentage in order to reduce the surface roughness, particularly preferably _{_{Ti0 2 / Si0 2 = 2 Z}} 8~ 5 Z 5.

Preferable specific examples of the alkali silicate (C) include alkali silicates represented by the general formula Me ₂ 〇 · nSi 0 ₂ (where Me represents an alkali metal) (for example, water glass, silicate Potassium, lithium silicate, and sodium silicate). Further, the alkali metal silicates may be used as a mixture or a composite. In the present invention, the alkali metal silicate-containing solution contains Fr, Cs, Rb, K, Na, and And at least one metal selected from the group consisting of Li. Also, instead of alkali metal salts, alkali silicates such as ammonium silicate may be used.

The alkali silicate (C) preferably contains 10 to 40% by weight of the total solids of 100% by weight. Alkali metal silicates are cured immediately after coating at room temperature, so they are suitable for in-situ coating, which cannot be heated, and can compensate for the disadvantages of alkyl silicate (B), which has a slow curing rate. In order to prevent the film from being damaged by watering or touching with a finger 30 minutes after application, 100% by weight of alkali silicate (C) was added to 100% by weight of the total solid content. It is preferable to include the above. In addition, alkali silicate (C) has a large amount of non-crosslinking oxygen and has a function of maintaining hydrophilicity in the absence of light. To make it hydrophilic immediately after coating or to maintain hydrophilicity in dark places. In addition, it is preferable to contain 10% by weight or more. Further, when the non-woven fabric is impregnated with the photocatalytic hydrophilic coating agent of the present invention and then applied to the substrate, if the alkali silicate (C) is too much, the liquid will gather in a streak shape during drying, resulting in poor appearance. In order to maintain high transparency, the content is preferably less than 40% by weight based on the total solid content. Particularly, in order to achieve both high transparency and maintenance of hydrophilicity such as a glass substrate, it is particularly preferable that the alkali metal silicate (C) contains 10 to 20% by weight of the total solid content of 100% by weight. .

Alcohols (D) include methanol, ethanol, 1-propanol, 2-propanol, t-butanol, 2-butanol, and 1-butanol. These can be used alone or in combination of two or more. Of these, highly polar ethanol, methanol and 2-propanol, which are difficult to separate from water due to the salting-out effect of the alkali silicate during drying, are particularly preferred. To prevent freezing, it is preferable to add 5% by weight or more. . Further, in order not to cause gelation of the alkali silicate, the amount of alcohol added is preferably 20% by weight or less.

Examples of the surfactant (E) include polyhydric alcohol-type nonionic surfactants (eg, fatty acid monoester of glycerol, sorbitan ester, and fatty acid ester of sugar), and polyethylene glycol-type nonionic surfactant (such as higher alcohol). Polyoxyalkylene oxide adducts, alkylphenol polyoxyalkylene oxide adducts, fatty acid polyoxyalkylene oxide adducts, higher aliphatic amines Polyoxyalkylene oxide adducts, pull nick type nonionic surfactants, polyoxyalkylene oxide additives of polyhydric alcohol type nonionic surfactants, polyether-modified organosiloxanes, etc.), fatty acids Nonionic surfactants such as alcohol amides, perfluoroalkyl sulfonates, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adducts, perfluoroalkyltrimethylammonium salts, Perfluoroalkylaminosulfonate, oligomer containing perfluoroalkyl group (eg, “MegaFac” manufactured by Dainippon Ink and Chemicals, Inc.), perfluoroalkenyloxybenzenesulfonate , Perfluoroalkenyloxybenzenesulfonyl sarcocinnato Perfluoroalkenylpolyoxyethylene ether, perfluoroalkenyloxybenzamide alkylammonium hydroxide, perfluoroalkenyloxylalkylalkyl betaine, perfluoroalkenyloxyalkylalkylphosphone Acids, fluorinated surfactants such as diglycerin tetrakis (perfluoroalkenylpolyoxyethylene ether) (for example, “Futagent” manufactured by Neos Co., Ltd.), fatty acid salts (fatty acid soap, etc.) , Sulfate (α-sulfate sulphate, higher alcohol sulphate, fatty acid sulphate, sulphated oil, higher alcohol sulphate, alkyl phenol sulphate, etc.) , Sulfonate (α-olefin sulfonate, α-sulfonated fatty acid salt, α-sulfonated fatty acid ester salt, alkylbenzene sulfonate, igebon Α type, aerosol OT type, polystyrene sulfonate etc.), phosphate ester salt (phosphate ester salt of higher alcohol, higher grade) Anionic surfactants such as phosphoric acid ester salts of alcohol AOA), amine salt-type cationic surfactants (such as hydrochloride of higher aliphatic amines), and quaternary ammonium salt-type surfactants (alkyl) Cationic surfactants such as dimethyl pendant ammonium salt), amino acid-type amphoteric surfactants (such as sodium lauryl aminopropionate), betaine-type amphoteric surfactants (such as lauryl dimethyl betaine), and sulfate esters Salt type amphoteric surfactant, Sulfonate type amphoteric surfactant, Phosphate ester type amphoteric surfactant Amphoteric surfactants such as the active agent, and the like. The addition amount of the surfactant (E) is preferably from 0.001 to 0.3% by weight. If the content is less than 0.001% by weight, there is no effect of improving the leveling property and the viscosity, and if the content is more than 0.3% by weight, the coating film is whitened and the appearance is poor. Examples of the polymeric thickener (F) include water-soluble polymers, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, xanthan gum, guar gum, agar, dextrin, starch, pectin, sodium alginate , Arabic gum, Gelatin, Lignin sulfonate, Polyethylene glycol, Polypropylene glycol, Polyoxyvinyl polymer, Acrylic ester polymer, Polyacrylate, Polyacrylamide, Polyvinyl alcohol, Polyvinylpyrrolidone, Polyvinyl acetate, Polyvinyl acetate Compound, acrylic acid ester polymer, isobutyl maleic acid copolymer, acrylic acid Z-methacrylic acid copolymer, acrylic acid Z Use may be made of, for example, a lactic acid copolymer, a methyl vinyl ether maleic anhydride copolymer, a urethane resin, an acrylic resin, and the like.

The amount of the polymer thickener (F) to be added is preferably 0.05 to 0.3% by weight.

Addition of less than 0.005% by weight does not have the effect of improving the viscosity, while addition of more than 0.3% by weight is not preferable because the coating film is whitened and poor appearance is caused.

Any preservative or fungicide (G) can be used as long as it is water-soluble. Among them, salts containing copper ions such as copper sulfate and ionic ones such as sodium azide can be particularly preferably used. Copper ions are easily precipitated by alkalization and can be suitably used at less than 200 ppm, and sodium azide is preferably 0.1% by weight or less from the viewpoint of toxicity.

In the photocatalytic hydrophilic coating agent of the present invention, a fragrance, an antioxidant, a chelating agent, an antifoaming agent and the like may be mixed or used in combination, if necessary.

The method of applying the composition according to the present invention to the surface of the substrate may be appropriately selected. Examples thereof include a spray coating method, an aerosol coating method, a dip coating method, a flow coating method, a spin coating method, a roll coating method, and a brush. Methods such as coating, sponge coating, and non-woven fabric coating can be suitably used.

The product form of the photocatalytic hydrophilic coating agent of the present invention includes aerosol spray, A hand spray, a container form in which the nonwoven fabric or sponge for application is integrated with the bottle, and the liquid is leached from the bottle through the nonwoven fabric or the like described above. Further, a product obtained by impregnating a nonwoven fabric, sponge, cloth, paper, or the like with the present composition can be sealed in a pack formed of resin-laminate film to obtain a product.

As the product form of the photocatalytic hydrophilic coating agent of the present invention, it is particularly preferable that the nonwoven fabric is impregnated with a fixed amount of the solution and applied to the user in order to keep the amount of the coating solution constant. In this case, as the material of the nonwoven fabric, regenerated cellulose fibers having good water retention, such as picose rayon, Cubraammonium rayon, and lyocell, are particularly preferable. In addition, for easy use by the user, a non-woven fabric can be impregnated with a fixed amount of a photocatalytic hydrophilic coating agent, and the product can be enclosed in a resin or laminate film pack to form a product. At this time, it is desirable that the film contains an aluminum foil layer to impart strength. A layer of polyacrylonitrile or polyolefin is particularly desirable on the liquid contact surface to prevent loss of adsorption of the photocatalytic metal oxide (A).

The hydrophilicity-restoring agent of the present invention can be used for a photocatalytic hydrophilic film whose hydrophilicity has been impaired by the attachment of a contaminant. Substrates to be used in anti-fog applications include glass, transparent plastics, lenses, and prisms. It is a transparent substrate such as a mirror.

More specifically, mirrors such as bathroom or toilet mirrors, vehicle rearview mirrors, dental tooth mirrors, road mirrors; spectacle lenses, optical lenses, camera lenses, endoscope lenses, illumination lenses, Lenses such as semiconductor manufacturing lenses; prisms; windows of buildings and watchtowers; vehicles such as cars, railcars, aircraft, ships, submersibles, snowmobiles, ropeway gondolaes, amusement park gondolas, and spacecraft Windshields for vehicles such as cars, railway vehicles, aircraft, ships, submersibles, snowmobiles, snowmobiles, motorcycles, ropeway gondolaes, amusement park gondolas; protective or sport goggles Or shields for masks (including diving masks); helmet shields; glass for frozen food display cases; cover glass for measuring instruments; and Adhered possible film to these products goods, is the emblem and the like.

In outdoor applications where self-purification by rainfall can be expected, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, fabric, paper, combinations thereof, and lamination of them Body, their painted body And so on.

More specifically, building exteriors such as exterior walls and roofs; window frames; exteriors and coatings of vehicles such as cars, railcars, airplanes, ships, bicycles, and motorcycles; windowpanes; signboards, traffic signs, soundproofing. Walls, greenhouses, insulators, vehicle covers, tent materials, reflectors, shutters, screen doors, covers for solar cells, covers for collectors such as solar water heaters, street lights, pavements, outdoor lighting, artificial waterfalls, artificial fountains Stones, tiles, bridges, greenhouses, exterior wall materials, seals between walls and glass, guardrails, verandas, vending machines, air conditioner outdoor units, outdoor benches, various display devices, shutters, toll booths, charge boxes, Roof gutters, vehicle lamps, protective covers, dust-proof covers and coatings, coating of machinery and articles, exterior and coating of advertising towers, structural members, and films and patches that can be attached to those articles A. Substrates targeted for applications where cleaning by water washing can be expected include, for example, metals, ceramics, glass, plastic, wood, stone, cement, concrete, fibers, fabrics, paper, combinations thereof, and laminations thereof. Bodies, their painted bodies, etc.

More specifically, not only the above outdoor use materials are included, but also other materials such as building interior materials, window glass, housing equipment, toilet bowl, bathtub, wash basin, lighting fixtures, kitchenware, tableware, dish dryers, These include sinks, cooking ranges, kitchen hoods, ventilation fans, window rails, window frames, tunnel inner walls, tunnel lighting, and films and patches that can be attached to these items.

Substrates that can be expected to promote drying include, for example, window sashes, radiating fins for heat exchangers, pavements, bathroom toilet mirrors, greenhouse ceilings, vanities, automobile bodies and their products. Possible films, patches, etc. The optical excitation of the optical semiconductor is performed by irradiating the optical semiconductor with light having energy larger than the energy gap (ie, shorter wavelength) between the conduction electron band and the valence band of the optical semiconductor crystal.

More specifically, the wavelength is 387 ηm or less when the optical semiconductor is an analog-type titanium oxide, the wavelength is 413 nm or less when the rutile titanium oxide is used, and the wavelength is when the tin oxide is tin oxide. Irradiate a light beam containing light with a wavelength of 344 nm or less, or in the case of zinc oxide, a wavelength of 378 nm or less.

In the case of the above-mentioned optical semiconductor, since it is photoexcited by an ultraviolet light source, Indoor lighting such as fluorescent lamps, incandescent lamps, metal halide lamps, and mercury lamps, solar light, and light sources that guide these light sources with low-loss fibers can be used.

The illuminance of light necessary for photoexcitation of the optical semiconductor required for hydrophilizing the composite material surface is 0.000 lmWZcms or more, preferably 0.001 mW / cm2 or more, more preferably 0.01 mW / c or more. m2 or more.

The photocatalytic coating composition is a group of silver, copper, palladium, platinum, rhodium, platinum, ruthenium, gold, zinc, cobalt, iron, nickel, sodium, lithium, strontium, potassium, calcium, magnesium, or a compound of these metals. One or more selected from the following 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 and compounds of these metals, it is possible to improve the oxidation-reduction catalytic performance of the optical semiconductor by photoexcitation. it can.

The photocatalytic coating composition can include a substance having a refractive index of 2 or less. The addition of a substance having a refractive index of 2 or less has the advantage that visible light can be effectively prevented from being reflected on the applied surface.

Substances with a refractive index of 2 or less that can be added to the photocatalyst coating composition include silicic acid (refractive index: 1.5), tin oxide (1.9), calcium carbonate (1.6), and hydroxylic acid. (1.6), Magnesium carbonate (1.5), Strontium carbonate (1.5), Dolomite (1.7), Calcium fluoride (1.4), Magnesium fluoride (1) 4), Alumina (same as 1.6), Kee sand (same as 1.6), Zeolite (same as above)

1.5), Montmorillonite (1.5), Kaolin (1.6), Sericite (1.6)

1.6), ferric oxide (1.8) and yttrium oxide (1.9).

When a coating film is formed on the member surface by the above method, the member surface becomes hydrophilic in response to 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 may be 0.001 mW / cm2 or more, but 0.01 mW / cm2. More preferably, it is more than 0.1 mWZ cm2.

When the photocatalytic oxide is anatase-type titanium oxide, rutile-type titanium oxide, zinc oxide, or strontium titanate, the light source used for photoexcitation of the photocatalyst is a solar light, indoor lighting, a fluorescent lamp, a mercury lamp, an incandescent lamp, Xenon lamps, high-pressure sodium lamps, metal halide lamps, BLB lamps, etc. can be suitably used. When the photocatalytic oxide is tin oxide, a germicidal lamp, a BLB lamp, or the like can be suitably used.

The thickness of the surface layer formed by a coating film on the member surface is preferably set to 0.4 m or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent.

More preferably, the thickness of the surface layer is set to 0.2 or less. By doing so, it is possible to prevent coloration of the surface layer due to light interference.

Also, the thinner the surface layer, the better its transparency. Further, if the film thickness is reduced, the wear resistance of the surface layer is improved.

(Example 1)

Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto. % In Examples and Comparative Examples indicates% by weight.

Table 1 shows the compositions of the photocatalytic hydrophilic coating agents # 1 to # 4 of the present invention and Comparative Examples 1 to 3. As the mixing method in preparing the composition, # 1 to # 4 and Comparative Examples 1 and 2 were prepared by diluting S1 with water (deionized water or distilled water) in order to avoid a sharp pH change in And mixed slowly. During the addition, T1 was constantly stirred with a magnetic stirrer. In Comparative Example 3, 11-propanol was gradually added to T2 and mixed. During the addition, T 2 was constantly stirred with a magnetic stirrer. 【table 1】

Notes for Table 1

T 1 “STS_200” manufactured by Ishihara Sangyo Co., Ltd. (analyte type titanium dioxide and methyl silicate: 4.8% by weight, water, methanol and 2_propanol: 95.

2% by weight, weight ratio of titanium dioxide = 5Z5, pH 6.1)

T2 “ST-Κ03” manufactured by Ishihara Sangyo Co., Ltd. (analyte type titanium dioxide and ethyl silicate 10% by weight in total, 2-propanol, water, methanol and nitric acid in total 9

0 wt%, titanium dioxide / silica weight ratio = 55, acidic)

S 1 "1Κ Gay potassium" Nippon Chemical Industrial Co., Ltd. (S I_〇 ₂ = 27 to 29% by weight,

(K ₂ 〇 = 21-23% by weight)

(Evaluation 1; hydrophilicity immediately after application)

On the surface of soda lime glass (size: 10 Omm x 10 Omm X 2 mm), the compositions # 1 to 4 and Comparative Examples 1 to 3 shown in Table 1 were prepared using Asahi Kasei Corporation's cupra nonwoven fabric “Benrize TS_100” ( (Size: 20 OmmX 265 mm) was impregnated with 14 g, and slid in one direction at a speed of 30 cmZs and smeared. After the coated glass was dried at room temperature (251 :) for 30 minutes, the contact angle of the coating with water was measured, and the contact angle with water immediately after coating was determined.

[Table 2]

Table 2 shows the contact angle of the coating film surface with water immediately after application. Of the total solid content of 100% by weight, the photocatalytic hydrophilic coating agents # 1 to # 4 containing 10 to 40% by weight of alkali silicate had a contact angle of 10 degrees or less. On the other hand, in Comparative Examples 1 to 3 in which the content of the alkali silicate was 10% by weight or less, the temperature was higher than 10 degrees, and particularly in Comparative Examples 2 to 3 containing no alkali silicate, the temperature was higher than 20 degrees.

(Evaluation 2; maintainability of hydrophilicity in 喑 place)

The compositions # 1 to 4 and Comparative Examples 1 to 2 shown in Table 1 were applied to the surface of soda lime glass (size: 10 O mm X 10 O mm X 2 mm) under the same conditions as in Evaluation 1, and Dried for 30 minutes at warm (at 25). Figure 1 shows the change over time of the contact angle of the coating film surface with water in a dark place after coating. Of the total solid content of 100% by weight, the photocatalytic hydrophilic coating agents # 1 to # 4 containing 10 to 40% by weight of alkali silicate maintained a contact angle of 30 ° or less for 16 hours after application. . Comparative Example 1 containing 8.7% by weight of the alkali silicate gave almost the same results. On the other hand, Comparative Example 2 containing no alkali silicate had a temperature of 40 ° C. or higher.

(Evaluation 3: Effect of improving physical strength of film)

The compositions # 1 to # 4 and Comparative Examples 1 and 2 shown in Table 1 were applied to the surface of soda lime glass (size: 10 O mm x 10 O mm X 2 mm) under the same conditions as in Evaluation 1. After the coating was dried at room temperature (at 25) for 24 hours, the surface of the coating was rubbed with a finger and the appearance of the coating was visually observed. Table 3 shows the results. Of the total solids of 100% by weight, the higher the concentration of alkali silicate, the higher the physical height of the membrane. Photocatalytic hydrophilic coating agent containing 10 to 40% by weight of alkali silicate # 1 to # 4 hardly rubs with fingers Although the whitening did not occur or the whitening was slight, in Comparative Examples 1 and 2, the physical strength of the film was weak and the whitening was clearly observed.

[Table 3]

(Evaluation 4: Effect of improving the water resistance of the film)

The compositions # 1 to # 4 and Comparative Examples 1 and 2 shown in Table 1 were applied to the surface of soda lime glass (size: 10 OmmX 10 OmmX 2 mm) under the same conditions as in Evaluation 1. After coating, the coating was dried at room temperature (25) for 30 minutes, and then tap water was showered at 6 LZ for 20 minutes, and the peeling state of the film was observed. Table 4 shows the results. Since the photocatalytic hydrophilic coating agents # 1 to # 4 did not change their visual appearance and their contact angles remained low, it was judged that the films did not peel. In Comparative Examples 1 and 2, whitening and film flow were observed immediately after showering, and it was determined that the film was peeled.

[Table 4]

(Evaluation 5: Appearance of coating film)

Compositions # 1 to # 4 and Comparative Examples 1 to 2 shown in Table 1 were applied to the surface of soda lime glass (size: 10 OmmX 10 OmmX 2 mm) under the same conditions as in Evaluation 1. After the coating was dried at room temperature (25) for 30 minutes, the coating film surface was visually observed. The results are shown in Table 5. The visual appearance of the photocatalytic hydrophilic coating agents # 1 to # 2 is almost the same as before coating. Very good, almost unchanged. The photocatalytic hydrophilic coating agents # 3 to # 4 were slightly conspicuous. For substrates that require extremely high transparency, photocatalytic hydrophilic coating agents # 1 to # 2 containing 100 to 20% by weight of alkali silicate out of 100% by weight of the total solids are used. If priority is given to maintaining hydrophilicity without any problems even if some streaks appear, photocatalytic hydrophilic coating agents # 3 to # 4 containing 20 to 40% by weight of aluminum silicate are suitable. Was. The appearance of the coating films of Comparative Examples 1 and 2 was good.

[Table 5]

Notes to Table 5

◎: very good

〇: good

△: Slightly noticeable streaks

X: Bad (Example 2)

Table 6 shows the compositions of the photocatalytic hydrophilic coating agents # 5 to # 9 of the present invention and Comparative Examples 4 to 5.

[Table 6]

Composition Photocatalytic metal oxide + Alkali metal silicate Solvent

Norekirke silicate

T1 S 1 Water Ethanol

# 5 8.75% 0.12% 91.13% 0%

# 6 8.75% 0.12% 86.13% 5%

# 7 8.75% 0.12% 81.13% 10%

# 8 8.75% 0.12% 76.13% 15%

# 9 8.75% 0.12% 71.13% 20% Comparative Example 4 8.75% 0.12% 66.13% 25% Comparative Example 5 8.75% 0.12% 61.13% 30% Notes to Table 6

T 1 “STS_200” manufactured by Ishihara Sangyo Co., Ltd. (anatase type titanium dioxide and methyl silicate in total 4.8% by weight, water, methanol and 2-propanol in total 95.2% by weight, titanium dioxide Z silica weight ratio = 5) 5, pH 6.1 1)

S 1 "1K Gay potassium" Nippon Chemical Industrial Co., Ltd. (S i 0 ₂ = 27~29 wt%, Κ ₂ 0 = 21~23 wt%) of Table 6 of the composition to room temperature (25 ° C) Table 7 shows the results of the presence or absence of coagulation and sedimentation after storage for one week and the presence or absence of freezing after storage at -10 ° C for one week. The photocatalytic hydrophilic coating agents # 5 to # 9 of the present invention containing 0 to 20% by weight of ethanol did not aggregate and precipitate. On the other hand, in Comparative Examples 4 and 5 containing 25% by weight or more of ethanol, the hydrated water of the alkali silicate was gelled due to the dehydration of the hydrated water, resulting in aggregation and precipitation. The photocatalytic hydrophilic coating agents # 6 to # 9 of the present invention containing 5 to 20% by weight of ethanol did not freeze even at -1 O :.

[Table 7]

Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the photocatalytic hydrophilic coating agent which makes the surface of a member highly hydrophilic while maintaining high transparency easily on site.

Claims

The scope of the claims

1. Contains water and photocatalytic metal oxide (A;), alkyl silicate (B) and alkali silicate (C), and contains solid components of photocatalytic metal oxide (A) and alkyl silicate (B) ratio is T I_〇 _{_{2 ZS i 0 2 = 2 /}} 8~8Z2, of the total solid content of 100 wt%, the photocatalytic hydrophilic coating agent comprising 10 to 40 wt% alkali silicate.

2. A photocatalytic hydrophilic coating agent containing 10 to 20% by weight of an alkali silicate based on 100% by weight of the total solid content of the photocatalytic hydrophilic coating agent according to claim 1.

3. A photocatalytic hydrophilic coating agent, wherein the solid concentration of the photocatalytic hydrophilic coating agent according to any one of claims 1 to 2 is 0.1 to 1% by weight.

4. The photocatalytic metal oxide (A) in the photocatalytic hydrophilic coating agent according to any one of claims 1 to 3 is an anase-type titanium oxide or a brookite-type titanium oxide. Yes, a photocatalytic hydrophilic coating agent that is particles having an average crystallite size of 1 to 100 nm.

5. A photocatalytic hydrophilic coating agent, wherein the titania sol according to any one of claims 1 to 4 is neutral or alkaline.

6. The photocatalytic hydrophilic coating agent according to any one of claims 1 to 5, wherein the photocatalytic hydrophilic coating agent contains a titania sol whose surface is covered with silicide force.

7. A photocatalytic hydrophilic coating agent, wherein the alkali silicate (C) in the photocatalytic hydrophilic coating agent according to any one of claims 1 to 6 is an alkali metal silicate.

8. The photocatalytic hydrophilic coating agent according to any one of claims 1 to 7, wherein the solvent contains 5 to 20% by weight of alcohol (D).

9. The photocatalytic hydrophilic coating agent according to any one of claims 1 to 8, wherein the surfactant (E) is contained in an amount of 0.001 to 0.3% by weight.

10. The photocatalytic hydrophilic coat according to any one of claims 1 to 9, further comprising 0.0005 to 0.3% by weight of the polymer thickener (F). Agent.

11. The photocatalytic hydrophilic coating agent according to any one of claims 1 to 10, further comprising a preservative or an antifungal agent (G).

12. A method for applying the photocatalytic hydrophilic coating agent according to any one of claims 1 to 11.

13. The method for applying a photocatalytic hydrophilic coating agent according to claim 12, wherein a predetermined amount of the photocatalytic hydrophilic coating agent is impregnated into a nonwoven fabric and applied.

14. A packaging material in which a non-woven fabric is impregnated with a predetermined amount of the photocatalytic hydrophilic coating agent according to claim 13.