JPH11262730A - Production of hydrophilic composite material having photocataly tic film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a hydrophilic composite material equipped with a photocatalytic coating film developing chemical resistance, mechanical resistance, photocatalytic decomposition activity and hydrophylic function by photo-exitation without adding a substance unrelated to photocatalytic activity or the hydrophilic function by photo-excitation. SOLUTION: In the method for producing a hydrophilic composite material equipped with a base material and the photocatalytic film containing the photocatalytic material and silica-containing photocatalytic coating applied on the surface of the base material, a coating compsn. containing a coating film forming element consisting of silica produced by the hydrolysis of a silica precursor using a hydrolyzable catalyst and the photocatalytic material is prepared and, after the coating compsn. is applied to the surface of the base material, the coating film forming element is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a hydrophilic composite material provided with a photocatalytic coating capable of making and maintaining the surface of a substrate hydrophilic.

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-9-328336, it has been the mainstream to add a Zr element-containing compound to a photocatalyst as a method for improving chemical resistance and mechanical strength. The details found in the publication are as follows. (1) TiO ₂ fine particles having an average particle size of less than 100 nm;
(2) It contains a Zr element-containing compound and (3) a Si element-containing compound, and has a weight ratio of (2) /
(1) 0.02-0.5, (3) / (1) 0.2-
2.5, a composition formed using the composition, and a composition capable of easily forming a film having excellent photocatalytic activity, mechanical strength and chemical resistance, and a composition formed using the composition. Providing a coating. Conventionally, it has been said that ZrO ₂ , which is one of the Zr element-containing compounds, improves the alkali solution resistance performance when added to glass or the like. However, since hydrophilicity due to photoexcitation is easily damaged and the antifouling function is reduced, the amount of addition is limited, and sufficient chemical resistance may not be exhibited in some cases.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and without adding a substance irrelevant to the photocatalytic activity or the function of hydrophilization by photoexcitation, the chemical resistance and the mechanical resistance are improved. It is an object of the present invention to provide a method for producing a hydrophilic composite material provided with a photocatalytic coating exhibiting a hydrolytic function by photo-catalytic decomposition activity and photoexcitation.

[0004]

Means for Solving the Problems In order to achieve the above object, a hydrophilic composite material comprising a substrate and a photocatalytic coating containing a photocatalytic material and silica or a precursor thereof on the surface of the substrate. Comprising: (a) preparing silica; (b) applying a suspension containing a photocatalytic material and the silica or a precursor thereof to a surface; Curing a turbid liquid, and a method for producing a hydrophilic composite material provided with a photocatalytic coating.

In a preferred embodiment of the present invention, the step (c) is to leave (curing) the coated product for at least one day after coating.

In a preferred embodiment of the present invention, the step (a) comprises using a hydrolyzable catalyst when producing silica from a silica precursor by hydrolysis.
It is preferable that nitric acid is used as the hydrolyzable catalyst, and the amount thereof is 0.03 parts by weight or more based on 1 part by weight of the silica precursor.

In a preferred embodiment of the present invention, the step (c) comprises leaving (curing) the coated product for at least one day in a humidity atmosphere of 50% or less after coating.

[0008] In a preferred embodiment of the present invention, the step (c) is that after coating, the coated product is left (cured) for at least one day in an amine-based catalyst atmosphere or a solution thereof and then used.

[0009]

Next, the components of the present invention will be described. The photocatalytic material here means that holes or conduction electrons are generated by the excitation of electrons in the valence band, possibly causing local stoichiometric defects on the surface, and the amount of chemisorbed water and physisorption exceeding the equilibrium amount. A substance capable of hydrophilizing the surface of a substrate by the action of adsorbing water. Specific substances are selected from the group of anatase-type titanium oxide, brookite-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, tungsten trioxide, ferric oxide, and strontium titanate. One or two or more of them can be used. Preferable examples of the silica precursor capable of forming a silica film with the coating composition according to the present invention include an average composition formula of Six _q O _{(4-q) / 2} (where
Is an alkoxy group or a halogen atom, and q is 0 <
(the number satisfies q <4).

A preferred example of a silica precursor capable of forming a silica coating is a tetrafunctional hydrolysis represented by the general formula SiX ₄ (where X is an alkoxy group or a halogen atom). Silane derivatives. 4 above
Preferred specific examples of the functional hydrolyzable silane derivative include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane, silanol, tetrachlorosilane, tetrabromosilane and the like.

Preferred specific examples of the silicate include a partial hydrolyzate and a dehydration condensate of the tetrafunctional hydrolyzable silane derivative. The amount of the precursor contained in the coating composition according to the present invention may be appropriately determined. For example, the amount is preferably 10 parts by weight or less, more preferably 5 parts by weight in terms of silica, based on 1 part by weight of photocatalyst particles. Or less, most preferably 1 part by weight or less. Further, it is preferably at least 0.05 part by weight, more preferably at least 0.1 part by weight, most preferably at least 0.2 part by weight.
It is more than weight part.

In the present invention, silicone, a precursor of silicone, a precursor of silica, hydroxyalkoxycellulose, hydroxyalkylcellulose, polyvinyl alcohol, a polyvinyl alcohol-polyvinyl acetate copolymer, urethane, amino group-containing condensate, etc. A water-soluble resin may be contained. By adding these substances,
Even at a temperature of about room temperature, a hydrophilic member excellent in fixability can be provided.

Here, the silicone precursor includes methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, n-propyltrimethoxysilane, and n-propyltrimethoxysilane. Propyltriethoxysilane, n-propyltripropoxysilane,
Isopropyltrimethoxysilane, isopropyltriethoxysilane, isopropyltripropoxysilane, methyltributoxysilane, ethyltributoxysilane,
n-propylbutoxysilane, isopropylbutoxysilane, phenyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-methacryloxypropyltriethoxysilane,
γ-methacryloxypropyltrimethoxysilane, γ-
Methacryloxypropyltripropoxysilane, β-
(3,4-epoxycyclohexyl) ethyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ
-Mercaptopropyltrimethoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, phenylmethyldiethoxysilane, phenylmethyldimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, phenyldimethoxysilane, A silane derivative such as phenyldiethoxysilane, a (partially) hydrolyzed product thereof, and one or more selected from the group consisting of a hydrolyzed / condensed product can be suitably used. As the silicone, those obtained by subjecting the above silicone precursor to hydrolysis and dehydration condensation as necessary can be used. As the silica precursor, tetraethoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, tetraisopropoxysilane, tetraalkoxysilane such as dimethoxydiethoxysilane; methyl silicate, ethyl silicate,
Alkyl silicates such as propyl silicate and butyl silicate can be suitably used.

The silica in the coating composition according to the present invention comprises:
Silica fine particles or a silica coating precursor may be used. It is considered that the silica fine particles efficiently fix the photocatalyst fine particles on the member surface. According to a preferred embodiment of the present invention, the average particle size of the silica fine particles is preferably from 1 to 1000 nm.
The average particle size of the silica fine particles can be determined, for example, by a dynamic laser scattering method.

In the present invention, silica is produced by hydrolyzing a silane compound as a silica precursor. Examples of the silica precursor hydrolysis catalyst used at this time include nitric acid, sulfuric acid, hydrochloric acid, propionic acid, acetic acid,
Maleic acid, adipic acid, fumaric acid, valeric acid, citric acid, lactic acid, butyric acid, malic acid, picric acid, formic acid, carbonic acid,
Phenol and the like.

The amount of the hydrolyzable catalyst is preferably at least 0.03 part by weight, more preferably at least 0.1 part by weight, most preferably at most 1 part by weight of the silica precursor. However, it is preferable to manufacture it at 0.3 parts by weight or more. Thus, when the hydrolyzable catalyst is added in this amount, it is considered that the network structure of silica in the coating film becomes dense and the number of Si—O bonds increases. Therefore, for example, when an alkali solution such as sodium hydroxide adheres to the coating film, sodium hydroxide and silica react with each other to generate a sodium salt, and at the same time, it is considered that the network structure of the silica is destroyed. However, in the silica state as described above, this reaction is a slight change when viewed from the whole film, and even if the film is destroyed by this, it takes time to destroy the entire film. Become. Therefore, it is considered that a long-lasting film is formed by performing the above-described operation even when the alkaline solution adheres. As described above, not only the alkali resistance, that is, the chemical resistance, but also the film strength can be improved by this operation, and the curing period can be shortened.

In the present invention, in the step of curing the suspension by leaving (curing) the coated product for at least one day after coating, the coated product is left in an atmosphere where the humidity is 50% RH or less. It is considered that performing (curing) promotes the dehydration condensation reaction that is considered to be performed in the coating. Then, it is considered that the reaction from the silanol group to the siloxane bond is accelerated, and the network structure of the silica in the coating film becomes dense and the number of Si—O bonds increases. Therefore, for example, when an alkali solution such as sodium hydroxide adheres to the coating film, sodium hydroxide and silica react with each other to generate a sodium salt, and at the same time, it is considered that the network structure of the silica is destroyed. But,
In the state of silica as described above, this reaction is a slight change when viewed from the whole film, and even if the film is destroyed by this reaction, it takes time to destroy the entire film. Therefore, it is considered that a long-lasting film is formed by performing the above-described operation even when the alkaline solution adheres. As described above, not only the alkali resistance, that is, the chemical resistance, but also the film strength can be improved by this operation, and the curing period can be shortened.

In the present invention, after the coating, the coated material is left (cured) for at least one day to cure the suspension.
A solution prepared by dissolving an amine-based dehydration / condensation catalyst such as an ethylamine solution in an alcohol-based solvent such as ethanol or an aromatic-based solvent such as toluene is prepared, and the coated member is immersed therein and allowed to stand. It is considered that the reaction from the silanol group to the siloxane bond is accelerated, and the network structure of the silica in the film becomes dense, and the number of Si—O bonds increases. Therefore, for example, when an alkali solution such as sodium hydroxide adheres to the coating film, sodium hydroxide and silica react with each other to generate a sodium salt, and at the same time, it is considered that the network structure of the silica is destroyed. However, in the silica state as described above, this reaction is a slight change when viewed from the whole film, and even if the film is destroyed by this, it takes time to destroy the entire film. Become. Therefore, it is considered that a long-lasting film is formed by performing the above-described operation even when the alkaline solution adheres. As described above, not only the alkali resistance, that is, the chemical resistance, but also the film strength can be improved by this operation, and the curing period can be shortened.

As the immersion solution for accelerating the dehydration condensation reaction, ammonia, ethanolamines such as aminopropyl alcohol, n-hexylamine, tributylamine, diazabicycloundecene, ethylenediamine in addition to the above ethylamine solution , Diethylenetriamine, hexanediamine, diethylenetriamine,
Triethylenetetramine, tetraethylenebentamine,
γ-aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane, γ
Amine compounds such as -aminopropylmethylmethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane; titanium compounds such as tetraisopropyl titanate and tetrabutyl titanate; aluminum triisobutoxide, aluminum triisopropoxide; Aluminum compounds such as aluminum acetylacetonate, aluminum perchlorate and aluminum chloride; metal-containing compounds such as cobalt octylate and cobalt acetylacetonate; acid oxides such as phosphoric acid, nitric acid and citric acid; iron acetylacetate Examples thereof include tin compounds such as nate, tin dibutyl dilaurate, and tin acetyl acetate. It is effective to use a plurality of these dehydration condensation catalysts in combination.

According to a preferred embodiment of the present invention, the composition according to the present invention may further comprise a surfactant. The surfactant is preferably added in an amount of less than 10 parts by weight, more preferably about 0.1 to 2 parts by weight, based on 1 part by weight of the photocatalyst particles.

Examples of surfactants that can be added to the composition according to the present invention include ammonium sulfonate polyoxyethylene alkylphenyl ether ether, sodium sulfonate polyoxyethylene alkylphenyl ether ether, fatty acid soap, fatty acid sodium soap, and the like.
Sodium dioctyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate soda salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfate soda salt, alkyl sulfate TEA salt, polyoxyethylene alkyl ether sulfate TEA salt, sodium 2-ethylhexylalkyl sulfate, sodium acylmethyltaurate, sodium lauroylmethyltaurate, sodium dodecylbenzenesulfonate, disodium lauryl sulfosuccinate, disodium lauryl polyoxyethylene sulfosuccinate, polycarboxylic acid, oleic acid Oil sarcosine, amide ether sulfate, lauroylza Koshineto, anionic surfactants such as sulfo-FA ester sodium salt; polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene acetyl ether,
Polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl phenol ether, polyoxyethylene nonyl phenol ether, polyoxyethylene octyl phenyl ether, polyoxyethylene laurate, poly Oxyethylene stearate, polyoxyethylene nonylphenyl ether, polyoxyethylene oleate, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, polyether-modified silicone, polyester-modified silicone, sorbitan laurate, sorbitan stearate, sorbitan palmitate , Sorbitan sosquioleate, sorbitan oleate, poly Xyethylene sorbitan laurate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, glycerol stearate, polyglycerin fatty acid ester, alkylalkylolamide, lauric acid diethanolamide, oleic acid diethanolamide Nonionic surfactants such as oxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxyethylene alkylpropylenediamine, polyoxyethyleneoxypropylene block polymer, and polyoxyethylene stearate; dimethylalkyl betaine; Surfactants such as alkylglycine, amidobetaine, imidazoline and the like; octadecyldi Tylbenzylammonium chloride, alkyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, dioleyldimethylbenzylammonium chloride, 1-hydroxy-2-alkylimidazoline quaternary salt, alkylisoquinolinium bromide, polymer amine, octadecyltrimethylammonium Chloride, alkyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride,
Cationic surfactants such as behenyltrimethylammonium chloride, alkylimidazoline quaternary salt, dialkyldimethylammonium chloride, octadecylamine acetate, tetradecylamine acetate, alkylpropylenediamine acetate, and didecyldimethylammonium chloride.

In a preferred embodiment of the invention, the composition according to the invention can comprise a polymerization curing catalyst. Examples of preferred polymerization curing catalysts include aluminum compounds such as aluminum chelate, aluminum acetylacetonate, aluminum perchlorate, aluminum chloride, aluminum isobutoxide and aluminum isopropoxide; tetraisopropyl titanate; Titanium compounds such as tetrabutyl titanate; lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, sodium formate, potassium acetate, potassium formate, potassium propionate, tetramethylammonium chloride And basic compounds such as tetramethylammonium hydroxide; n-hexylamine, tributylamine, diazabicroundecene, ethylenediamine, hexanediamine, diethylenetriamine, tetraethylamine. Lenpentamine, triethylenetetramine, ethanolamines, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane, γ- (2-aminoethyl) Amine compounds such as aminopropylmethyldimethoxysilane; tin acetylacetonate, dibutyltin octylate;
Metal compounds such as cobalt octylate, cobalt acetylacetonate, iron acetylacetonate; phosphoric acid, nitric acid, phthalic acid, p-toluenesulfonic acid, trichloroacetic acid And acidic compounds such as

In a preferred embodiment of the present invention, the composition according to the present invention may comprise a leveling agent so that it can form a smooth surface when applied to the surface of the component. The addition of a leveling agent is particularly advantageous when applying the composition according to the invention to large articles, ethylene glycol, monoacetone alcohol, diacetone alcohol, ethylene glycol monomethyl ether,
4-hydroxy-4-methyl-2-pentanone, dipropylene glycol, propylene glycol, tripropylene glycol, 1-ethoxy-2-propanol, 1
-Butoxy-2-propanol, 1-propoxy-2-
Propanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, diacetone alcohol
And cellosolve can be suitably used. The method of applying the composition of the present invention to the member surface may be appropriately selected,
For example, a spray coating method, a dip coating method, a flow coating method, a spin coating method, a roll coating method, a brush coating, a bar coating method,
A method such as sponge coating can be suitably used.

After being applied to the surface, the composition is dried or cured to form a thin film. During the course of drying or curing, the silica precursor becomes silica. Here, the drying may be either natural drying or drying by heating. Further, as long as the precursor becomes silica, a polymerization reaction by ultraviolet irradiation or the like may be caused.

The solvent contained in the composition according to the present invention is not limited as long as the photocatalyst particles and the precursor are stably dispersed and a hydrophilic surface is finally obtained.
Examples thereof include water or an organic solvent or a mixed solvent thereof. Particularly, water, alcohol, or a mixed solvent thereof is preferable. When alcohol is used as the solvent in the present invention, for example, methanol is used. Ethanol, n-propanol, isopropanol, t-butanol, isobutanol, n-butanol, 2-methylpropanol,
Pentanol, ethylene glycol, monoacetone alcohol, diacetone alcohol, ethylene glycol monomethyl ether, 4-hydroxy-4-methyl-2-
Pentanone, dipropylene glycol, propylene glycol, tripropylene glycol, 1-ethoxy-2
-Propanol, 1-butoxy-2-propanol, 1
-Propoxy-2-propanol, propylene glyco-
Monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether
Ter, tripropylene glycol monomethyl ether and the like can be suitably used.

The substrate to which the present invention can be applied is a transparent member when an anti-fogging effect is expected, and glass, plastic, or the like can be suitably used as the material. Speaking of applicable base materials, rear-view mirrors for vehicles, mirrors for bathrooms, mirrors for toilets, dental mirrors, mirrors such as road mirrors, spectacle lenses, optical lenses, lighting lenses, lenses for semiconductors, Lenses for copiers, lenses such as rear view camera lenses for vehicles, prisms, windows for buildings and watchtowers, automobiles, railway vehicles, aircraft, ships, submersibles, snowmobiles, lowway gondolas, amusement parks Gondolas, window glasses for vehicles such as spaceships, automobiles, motorcycles, railway vehicles, aircraft,
Ships, submersibles, snowmobiles, snowmobiles, gondolaes in lowways, gondolaes in amusement parks, windshields for vehicles such as spaceships, protective goggles, sports goggles,
Protective mask shields, sports mask shields, helmet shields, glass for frozen food display cases, glass for warm food products such as Chinese buns, measuring instrument Covers, covers for lasers such as converging lenses for laser treatment equipment and laser light detection sensors for inter-vehicle distance sensors, etc.
Cover of infrared sensor, filter for camera, and film, sheet, and sheet for attaching to the surface of the article
Includes

As a substrate to which 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,
Those laminates can be suitably used. Applicable base materials include 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, tunnel interiors and paintings, tunnel interiors and paintings, insulators, solar battery covers, solar water heater collector covers -, Vinyl houses, vehicle lighting covers,
Housing equipment, toilet bowl, bathtub, wash basin, lighting equipment, lighting cover, kitchenware, tableware, dishwasher, sink, cooking range,
Includes kitchen hoods, ventilation fans, and films, sheets, seals, etc. for attaching to the article surface.

As a substrate to which the present invention can be applied, when an antistatic effect is expected, its material is, for example, metal, ceramic, glass, plastic, wood, stone, cement, or the like.
Concrete, fibers, fabrics, combinations thereof, and laminates thereof can be suitably used. Speaking of applicable base materials, cathode ray tubes, magnetic recording media, optical recording media, magneto-optical recording media, audio tapes, video tapes
Housing, parts, exterior and coating for home appliances, analog records, home electric appliances, housing, parts and exterior and painting for OA equipment products, building materials, building exterior, building interior, window frames, window glass, structural members, vehicles Exteriors and coatings, exteriors of machinery and articles, dustproof covers and coatings, and films, sheets, seals, etc. for attaching to the surface of the articles.

[0029]

Example 1 Ethyl silicate 40 (manufactured by Colcoat) having a solid content of 40%: 6 g of methanol; 44.7 g of methanol (manufactured by Wako Pure Chemical Industries)
After mixing with a stirrer for about 5 minutes,
A 2% nitric acid solution prepared by diluting a 0% nitric acid solution (manufactured by Wako Pure Chemical Industries) with distilled water; 9.3 g is mixed while gently injecting. Thereafter, in order to advance the hydrolysis of the ethyl silicate 40, the mixture is stirred with a stirrer for 3 days in a thermostat set at 30 ° C. 25% of this 4% solution was diluted with a solvent prepared by mixing 17.5 g of diacetone alcohol (manufactured by Gordo solvent) and 17.5 g of n-propanol (manufactured by Wako Pure Chemical), and the diluted solution was used. 40 g of 10% nanotitania (NTS-1, manufactured by Showa Denko) is added to the mixture, and the mixture is stirred with a stirrer for 2 hours in a thermostat set at 30 ° C.
After stirring, the mixture is allowed to stand for one day under an atmosphere of normal temperature and normal humidity. Thereby, a coating agent for a superhydrophilic film having a solid content of 5%;
00g. The solid content concentration here refers to the total of the silica equivalent weights of the photocatalyst particles and the precursor. As a method of applying this coating agent to a mirror, first, the coating surface of a commercially available float plate glass or a mirror serving as a base material is thoroughly washed with a commercially available neutral detergent, and then the operation of rinsing with tap water is repeated three times or more. After that, the surface water is washed away with ethanol (manufactured by Wako Pure Chemical Industries), and finally washed with distilled water. At this time, if possible, an even better coating can be performed by performing cleaning using an ultrasonic cleaning machine. The substrate is subjected to corona discharge treatment or polishing treatment of the application surface with a ceria abrasive to make the surface hydrophilic, and then the coating agent is applied twice. As a coating method, a commonly used coating method such as a roll coater method or a reverse coater method can be used, and coating can be performed. After the application, the substrate is left (cured) in a normal temperature and normal humidity atmosphere for 2 hours and then dried in a dryer at 150 ° C. for 30 minutes. After drying, the coated material is allowed to stand still in an atmosphere of normal temperature and normal humidity, and left (cured) for one month.

Example 2 A coating agent was prepared in the same manner as in Example 1 except that the concentration of nitric acid used for hydrolysis of ethyl silicate 40 was 1%.
Is the same as

Comparative Example 1 The preparation of the coating agent was the same as in Example 1 except that the concentration of nitric acid used for hydrolysis of ethyl silicate 40 was 0.04%.

The evaluation methods used in the examples and comparative examples are as follows. Chemical resistance: After immersion in a 20% by weight aqueous solution of Na ₂ CO ₃ for 48 hours, changes in the appearance of the film were visually observed. In the chemical resistance evaluation, ◎: state where the film is completely attached, ○: state where the film is present but the waterline looks quite thin, Δ: state where the film is present but the waterline is clearly visible, ×: the film is completely peeled off State.

[0033]

[Table 1]

Example 3 The preparation of the coating agent was the same as in Example 1, and the method of leaving (curing) after coating was performed as follows. After a sample was prepared by applying a coating agent to a substrate, 1.0 g of ethylamine hydrochloride (manufactured by Wako Pure Chemical), 70 g of diacetone alcohol (manufactured by Gordo Solvent), and 123 g of aminopropanol (manufactured by Wako Pure Chemical); 123 g Is added to a solvent prepared by mixing the above, and stirred for about 10 minutes. At this time, a non-aqueous chemical is preferably used. Then, the solution is transferred to a petri dish with a lid, and the sample after standing (curing) is immersed in the solution with the coating surface facing upward. Next, the lid of the petri dish is covered, and the dish is left in a desiccator. After standing, cover the desiccator with the lid closed, and stand for 42 days or more, and leave (curing).
After standing (curing) is completed, the sample is washed with distilled water.

Example 4 The preparation of the coating agent was the same as in Example 1, and the method of leaving (curing) after coating was performed as follows. After preparing a sample by applying a coating agent to the base material, 1.0 g of ethylamine hydrochloride (manufactured by Wako Pure Chemical); 470 g of diacetone alcohol (manufactured by Gordo Solvent); 123 g of aminopropanol (manufactured by Wako Pure Chemical); Is added to a solvent prepared by mixing the above, and stirred for about 10 minutes. At this time, a non-aqueous chemical is preferably used. Then, the solution is transferred to a petri dish with a lid, and the sample after standing (curing) is immersed in the solution with the coating surface facing upward. Next, the lid of the petri dish is covered, and the dish is left in a desiccator. After standing, cover the desiccator with the lid closed, and stand for 42 days or more, and leave (curing). After standing (curing) is completed, the sample is washed with distilled water.

Example 5 The preparation of the coating agent was the same as in Example 1, and the method of leaving (curing) after coating was performed as follows. After applying the coating agent to the base material, the sample is allowed to stand in a small vacuum glove box device (manufactured by Miwa Seisakusho) equipped with a gas circulation purifier set in an argon atmosphere at a humidity near 0% RH. Then, it is left standing (curing) for about 43 days.

Comparative Example 2 The preparation of the coating agent was the same as in Example 1 except that the standing (curing) period was set to 44 days.

The evaluation methods used in the examples and comparative examples are as follows. Film strength: The film strength is evaluated by pencil hardness measurement. A pencil hardness tester (P type manufactured by Toyo Seiki) is used, and the evaluation judgment procedure conforms to JIS K5400.

[0039]

[Table 2]

[0040]

By using the manufacturing method of the present invention, it is possible to improve the film strength and the chemical resistance of the film.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08J 7/04 C08J 7/04 T (72) Inventor Koji Oshima 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Totoki Equipment Inside the corporation

Claims (6)

[Claims] 1. A method for producing a hydrophilic composite material provided with a photocatalytic coating comprising a substrate and a photocatalytic material and silica or a precursor thereof on the surface of the substrate, comprising: (B) applying a suspension containing a photocatalytic material and the silica or a precursor thereof to the surface; and (c) curing the suspension. . 2. The method according to claim 1, wherein in the step (c), after the coating, the coated product is left for at least one day. 3. The method according to claim 1, wherein the step (a) uses a hydrolyzable catalyst when producing silica by hydrolysis from a silica precursor. . 4. The method according to claim 3, wherein nitric acid is used as the hydrolyzable catalyst, and the amount of the nitric acid is 0.03 parts by weight or more based on 1 part by weight of the silica precursor. Production method. 5. The method according to claim 1, wherein in the step (c), after the coating, the coated material is left in a humidity atmosphere of 50% or less for at least one day or more. 6. In the step (c), after the coating, at least one coated product is placed in an amine-based catalyst atmosphere or a solution thereof.
The method according to claim 1, wherein the method is used after standing for at least one day.