JP5429043B2 - Photocatalyst coating liquid for forming hydrophilic film and hydrophilic photocatalyst film using the same - Google Patents

Description

The present invention relates to a photocatalyst coating solution for forming a hydrophilic film and a hydrophilic photocatalyst film using the same. More specifically, it is a photocatalyst coating solution for forming an aqueous and low-temperature curable hydrophilic film containing a water-soluble cage silsesquioxane and a water-soluble zirconium compound, which can be used as a binder or undercoat of a general photocatalyst. And a hydrophilic photocatalyst film comprising a cured product of the coating solution.

  The photocatalyst coating films formed on various substrate surfaces are such that the photocatalytic metal compound such as titanium oxide contained therein exhibits the decomposing power and hydrophilicity of organic substances by irradiation with light. It is used for deodorizing and antibacterial applications. Currently, such photocatalytic coatings are mainly applied to exterior tiles, glass, exterior wall coating, filters inside air cleaners, inorganic substrates (ceramics, metals, etc.), but organic materials such as plastic materials. In recent years, the application to is also actively studied (Patent Documents 1 and 2).

  When such a photocatalyst is applied to an organic substrate, it is a common practice to provide an undercoat layer between the photocatalyst layer and the substrate in order to avoid damage to the substrate due to photocatalytic action. However, the current undercoat liquid for photocatalyst or binder liquid for photocatalyst layer (1) can not form a film with sufficient performance unless it is baked at a high temperature exceeding 150 ° C. (2) It is cured at a relatively low temperature. Because it uses an organic solvent, it cannot be applied to a substrate that is not solvent resistant. (3) Although it is cured at a low temperature and uses a solvent that does not damage the substrate, the life of the coating solution itself is short. It has one of the disadvantages that it must be prepared as a liquid mixing type and used up immediately after compounding. In addition, these commercially available coating films are superhydrophilic while exhibiting a photocatalytic effect and exhibit high self-cleaning properties. However, if sufficient sunshine cannot be obtained due to bad weather, etc., the hydrophilicity decreases and self-cleaning is not possible. The current situation is that the cleaning property is lowered.

  Therefore, (1) it is low-temperature curable, (2) consists of a solvent solution that is safe and free of substrate damage, (3) the resulting coating has high hardness and transparency, and is always hydrophilic, (4) pot There has been a demand for a coating solution and a binder material that satisfy all of the conditions that the life and shelf life are sufficiently long.

JP 2006-116461 A JP 2006-272757 A

  The present invention has been made in view of the above-mentioned problems, and is capable of effectively satisfying the above conditions (1) to (4), and a hydrophilic photocatalyst using the same, and a hydrophilic photocatalyst using the same The object is to provide a coating.

As a result of intensive studies, the present inventors have found that the above object can be achieved by the following photocatalyst coating solution for forming a hydrophilic film and a hydrophilic photocatalyst film, and have completed the present invention.
That is, the present invention firstly
Photocatalytic particles,
Water-soluble cage-type silsesquioxane 0.01 to 100% by mass with respect to the photocatalyst particles, and 0.01 to 100% by mass with respect to the water-soluble zirconium compound photocatalyst particles
The photocatalyst coating liquid for hydrophilic film formation containing this is provided.
Secondly, the present invention consists of a cured product of the above coating solution, has photocatalytic properties, has a contact angle with water of 20 degrees or less, and has a contact angle with water of 20 degrees after standing in a dark place for 1 month. Provided is a hydrophilic photocatalyst film characterized by maintaining the following.

  The photocatalyst coating liquid of the present invention can use water, alcohol or a mixture thereof as a solvent, and can form a coating liquid that is safe and has no damage to the substrate. In addition, the photocatalyst coating solution of the present invention is cured in a short time even at a low temperature of about 90 ° C., and the resulting coating is excellent in transparency and hardness, and its surface exhibits hydrophilicity both before and after being left in the dark for 1 month. . Since all of the formed films are made of an inorganic material, film deterioration due to the photocatalyst hardly occurs. In addition, the coating itself exhibits water wettability without depending on the superhydrophilicity by the photocatalyst, so that the hydrophilicity continues even in a dark place and the self-cleaning property is unlikely to deteriorate. Therefore, the photocatalyst coating liquid of the present invention is excellent in both performance and handleability.

  Hereinafter, the present invention will be described in detail.

  The photocatalyst coating solution for forming a hydrophilic film according to the present invention contains photocatalyst particles, a predetermined amount of a water-soluble cage silsesquioxane, and a predetermined amount of a water-soluble zirconium compound, and is usually a photocatalyst. The particles are dispersed in a solvent, and the water-soluble cage silsesquioxane and the water-soluble zirconium compound are present in the coating solution in a state of being dissolved in the solvent.

[Water-soluble cage silsesquioxane]
The cage-type silsesquioxane refers to a silsesquioxane in which only a trifunctional siloxane unit (so-called T unit) is formed, and a silicon atom in the structure forms a vertex of a polyhedron. Any cage-type silsesquioxane can be used in the coating solution of the present invention as long as it is water-soluble. The water-soluble cage silsesquioxane is preferably soluble alone as well as in water. The water-soluble cage silsesquioxane may be used alone or in combination of two or more. Examples of the water-soluble cage silsesquioxane include the following structural formula (1):

（式中、Rは独立に水素原子または官能基である。）
で表されるT³ ₈構造を有するカゴ型シルセスキオキサン、下記構造式（２）：

(In the formula, R is independently a hydrogen atom or a functional group.)
A cage-type silsesquioxane having a T ³ ₈ structure represented by the following structural formula (2):

（式中、Rは前記のとおりである）
で表されるT³ ₁₀構造を有するカゴ型シルセスキオキサン、下記構造式（３）：

(Wherein R is as defined above)
A cage-type silsesquioxane having a T ³ ₁₀ structure represented by the following structural formula (3):

（式中、Rは前記のとおりである）
で表されるT³ ₁₂構造を有するカゴ型シルセスキオキサンが挙げられる。これらのうち、上記T³ ₈構造を有するカゴ型シルセスキオキサンが好適に使用できる。

(Wherein R is as defined above)
And cage-type silsesquioxane having a T ³ ₁₂ structure represented by: Of these, the cage silsesquioxane having the T ³ ₈ structure can be preferably used.

R is independently a hydrogen atom or a functional group. R may be the same as or different from each other. R is a functional group, for example, as a hydroxy group or a salt thereof: —O ⁻ M ⁺ (wherein M is a cation, for example, a quaternary ammonium ion such as tetramethylammonium or tetraethylammonium; an ammonium ion; A group represented by an alkali metal ion such as sodium ion); 1,2-propanediol group (—CH ₂ CH (OH) CH ₂ OH); 1,2-propanediol oxypropyl group (—C ₃ H ₆ OCH ₂ CH (OH) CH ₂ OH); cyclohexanediol group (—Cy (OH) ₂ , Cy is a cyclohexane ring, OH is bonded to any position on Cy); cyclohexanediol ethyl group (—C ₂ H ₄ Cy (OH) ₂ , Cy is as described above; a carboxy group or a salt thereof as a group represented by the formula: —COO ⁻ M ⁺ (wherein M is as described above); a sulfo group as (-SO ₃ H), or a salt thereof formula: -SO ₃ ^- M ⁺ (wherein, M is the . A cage) a group represented by; phosphono group _{(-P (OH) 2 O)} , or Formula :-P salt thereof _{^{(OH) 2 O - M +}} ( wherein, M is as the Group); an alkylol group such as a methylol group (—CH ₂ OH), an ethylol group (—CH ₂ CH ₂ OH); a polyether group (for example, the formula: — (OR ¹ ) _n —OR ² Wherein R ¹ is an alkylene group such as an ethylene group (—CH ₂ CH ₂ —), and R ² is a hydrogen atom or an alkyl group such as a methyl group, a formula: — ( R ¹ O) _n -R ² (wherein R ¹ and R ² are as defined above, etc.); mercapto group; mercaptopropyl group (—CH ₂ CH ₂ CH ₂ SH); amino Group: aminoethyl group (—CH ₂ CH ₂ NH ₂ ); substituted aminopropyl group (—CH ₂ CH ₂ CH ₂ N ⁺ H _x R ³ _3-x A ⁻ ; x is an integer of 1 to ³ , R ³ is Alkyl groups such as methyl, ethyl, propyl and butyl; One); 2-aminoethyl-3-aminopropyl group _{(-C 3 H 6 NHC 2 H} 4 NH 2); aminophenyl group (-PhNH _2, however, Ph is phenyl group); N-phenyl-aminopropyl group ( -CH ₂ CH ₂ CH ₂ NHPh, Ph is as described above); glycidyl group; glycidyloxypropyl group (-C ₃ H ₆ OG, where G is glycidyl group); alicyclic epoxy group such as epoxycyclohexyl group; A group represented by the formula: -C ₂ H ₄ -E or the formula: -CH ₂ -E (wherein E is an alicyclic epoxy group such as an epoxycyclohexyl group); a propylamic acid group (-C ₃ H ₆ NHCOCHCHCO (OH)); trifluoropropyl group (—CH ₂ CH ₂ CF ₃ ); chloropropyl group (—C ₃ H ₆ Cl); chlorophenyl group (—PhCl, where Ph is a phenyl group); chlorophenylethyl group ( -C ₂ H ₄ PhCl, however, Ph is phenyl group); chlorobenzyl group (-BnCl, however, Bn is a benzyl group); click B benzyl ethyl group (-C ₂ H ₄ BnCl, however, Bn is a benzyl group); maleimide propyl _{(-C 3 H 6 -N (C} 1 OCHCHC 2 O), however, N of (C ¹ OCHCHC ² O) In the moiety, C ¹ and C ² carbon atoms are bonded to the same N atom to form a cyclic maleimide); acryloyloxypropyl group (—C ₃ H ₆ OCOCHCH ₂ ); methacryloyloxypropyl group (—C ₃ H ₆ OCOC (CH ₃ ) CH ₂ ); alkyl group such as methyl group and ethyl group; aromatic group such as phenyl group and phenylethyl group (-C ₂ H ₄ Ph, where Ph is phenyl group); ureido group (—NHCONH ₂ ); ureidopropyl group (—C ₃ H ₆ NHCONH ₂ ); cyano group (—CN), cyanopropyl group (—C ₃ H ₆ CN), isocyanate propyl group (—C ₃ H ₆ NCO), etc. The cage silsesquioxane represented by any one of the structural formulas (1) to (3), which is a group of

  A commercially available product can be used as the water-soluble cage silsesquioxane. As a commercial item, the product made from Hybrid Plastics, such as MS0860 (brand name), is mentioned, for example.

[Water-soluble zirconium compound]
The water-soluble zirconium compound includes a zirconium oxide compound and a precursor thereof. A water-soluble zirconium compound may be used individually by 1 type, or may use 2 or more types together. Examples of the water-soluble zirconium compound include zirconium oxide, zirconium hydroxide, zirconium oxychloride (zirconium oxychloride), zirconium sulfate, zirconium nitrate, zirconium hydrochloride, zirconium acetate, zirconium formate, zirconium carbonate, basic zirconium carbonate, zirconium carbonate. Ammonium, potassium zirconium carbonate, zirconium octylate, zirconium tetranormal propoxide, zirconium tetraacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate bis (ethylacetoacetate), zirconium tetraacetylacetonate, zirconium These hydrolysates or partial hydrolysates such as tributoxy monostearate And the like. A commercial item can be used as a water-soluble zirconium compound.

[solvent]
As the solvent for obtaining the coating liquid of the present invention, water is suitable, but alcohols such as methanol, ethanol and isopropanol, or a mixture of water and alcohol may be used. These alcohols may be used alone or in combination of two or more.

[Photocatalyst particles]
Any conventionally known photocatalyst particles can be used. A photocatalyst particle may be used individually by 1 type, or may use 2 or more types together. Examples of the photocatalyst particles include metal oxide crystal particles that are n-type semiconductors such as titanium oxide photocatalyst particles, tungsten oxide photocatalyst particles, zinc oxide photocatalyst particles, and niobium oxide photocatalyst particles that are currently on the market. Can be mentioned. More specifically, for example, anatase type titanium dioxide (TiO ₂ ), rutile type titanium dioxide, tungsten trioxide (WO ₃ ), zinc oxide (ZnO), Ga-doped zinc oxide (GZO), niobium oxide (Nb) ₂ O ₅ ).

  Furthermore, as the photocatalyst fine particles having high visible light activity, for example, the metal oxide crystal doped with a dopant element such as nitrogen, sulfur, phosphorus, or carbon, or the surface of the metal oxide with copper, iron, Examples include nickel, gold, silver, platinum, carbon and other different elements or compounds of the different elements such as hydroxide, chloride, nitride, sulfide and the like. More specifically, rutile-type titanium oxide carrying platinum, rutile-type titanium oxide carrying iron, rutile-type titanium oxide carrying copper, rutile-type titanium oxide carrying copper hydroxide, anatase-type titanium oxide carrying gold And tungsten trioxide carrying platinum.

  As the photocatalyst particles, those having a fine primary particle diameter, that is, those having a primary particle diameter of preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm are preferably used. When the primary particle size is larger than 100 nm, the transparency of the photocatalyst film may be lowered and the appearance may be impaired. In the present specification, the “average particle diameter” refers to a volume-based average particle diameter corresponding to 50% of the cumulative distribution obtained by a particle size distribution measuring apparatus using a dynamic light scattering method.

  Commercially available photocatalyst particles with high visible light activity include MPT-623 (trade name, visible light responsive photocatalyst, powder, rutile titanium dioxide carrying a platinum compound, manufactured by Ishihara Sangyo), MPT-625 (trade name) , Visible light responsive photocatalyst, powder, rutile titanium dioxide carrying an iron compound, manufactured by Ishihara Sangyo) and the like.

[Photocatalyst coating solution]
In the photocatalyst coating solution of the present invention, the above-mentioned photocatalyst particles are dispersed, and the water-soluble cage silsesquioxane and the water-soluble zirconium compound are dissolved. The photocatalyst coating liquid is prepared by, for example, preparing a photocatalyst dispersion liquid in which photocatalyst particles are dispersed in a solvent in advance, and mixing and stirring the solution in which the water-soluble cage silsesquioxane is dissolved and the solution in which the water-soluble zirconium compound is dissolved. To be prepared. In the coating solution thus prepared, it is presumed that a cage-type silsesquioxane-zirconia complex is formed.

  Content of the photocatalyst particle in the said photocatalyst coating liquid is 0.01-10 mass% with respect to this whole photocatalyst coating liquid, Preferably it is 0.1-5 mass%. When the content is less than 0.01% by mass, the antifouling activity due to the photocatalyst may be lowered.

  Further, the content of the water-soluble cage silsesquioxane in the coating solution is 0.01 to 100% by mass, preferably 0.1 to 90% by mass with respect to the photocatalyst particles. If the amount is less than 0.01% by mass, the strength of the film may be low and peeling or cracking may occur. If the amount is more than 100% by mass, the photocatalyst particles may be completely covered and the antifouling activity may be reduced.

The content of the water-soluble zirconium compound in the coating solution is 0.01 to 100% by mass, preferably 0.01 to 80% by mass, and more preferably 0.01 to 50% by mass with respect to the photocatalyst particles. If it is less than 0.01% by mass, the strength of the film is low, and peeling or cracking may occur. If the amount is more than 100% by mass, the amount of light reflected on the coating surface increases due to the high refractive index considered to be due to zirconia, leading to a decrease in the total light transmittance of the coating and an increase in the haze ratio, which may lead to a decrease in coating transparency. is there. Further, the photocatalyst particles are completely covered, and the antifouling activity may be lowered.

[Substrate]
The substrate to which the hydrophilic photocatalyst film-forming coating solution of the present invention is applied is not particularly limited as long as the hydrophilic photocatalyst film can be formed. Examples of the base material include organic materials and inorganic materials. Examples of inorganic materials include non-metallic inorganic materials and metallic inorganic materials. These can have various shapes according to their purposes and applications.

  Examples of organic materials include vinyl chloride resin, polyethylene, polypropylene, polycarbonate, acrylic resin, polyacetal, fluorine resin, silicone resin, ethylene-vinyl acetate copolymer (EVA), acrylonitrile-butadiene rubber (NBR), polyethylene terephthalate ( PET), polyethylene naphthalate (PEN), polyvinyl butyral (PVB), ethylene-vinyl alcohol copolymer (EVOH), polyimide resin, polyphenylene sulfide (PPS), polyether imide (PEI), polyether ether imide (PEEI) And synthetic resin materials such as polyetheretherketone (PEEK), melamine resin, phenolic resin, acrylonitrile-butadiene-styrene (ABS) resin; natural, synthetic or semi-synthetic fiber materials and fiber products. These may be commercialized into required shapes and configurations such as films, sheets, other molded products, and laminates.

  Examples of the nonmetallic inorganic material include glass, ceramic, and stone. These may be commercialized in various forms such as tiles, glass, mirrors, and design materials.

  Examples of the metal inorganic material include cast iron, steel material, iron, iron alloy, aluminum, aluminum alloy, nickel, nickel alloy, zinc die cast, etc., and these may be plated or organic materials may be used. It may be applied. Moreover, the metal plating film provided on the surface of nonmetallic inorganic material or organic material may be sufficient.

[Hydrophilic photocatalytic coating]
The hydrophilic photocatalyst coating of the present invention comprises a cured product of the above coating solution, has a water contact angle of 20 degrees or less and a thickness of 200 nm, has a total light transmittance of 85% or more, haze It is a hydrophilic photocatalyst film having a rate of 3.5% or less. As a method for forming the hydrophilic photocatalyst film of the present invention, for example,
The coating liquid of the present invention is applied to the surface of the substrate to form a coating film,
The method of drying and hardening the obtained coating film at the temperature of 50-200 degreeC is mentioned.

  Any conventionally known method can be used to apply the coating solution to the substrate. Specifically, the substrate is coated using a dip coating method, spin coating method, spray coating method, brush coating method, impregnation method, roll method, wire bar method, die coating method, gravure printing method, ink jet method, etc. Can be formed on top.

  In order to dry and cure the coating film on the substrate, it is preferable to heat-treat for 1 to 120 minutes in a temperature range of 50 to 200 ° C., particularly in a temperature range of 60 to 110 ° C. for 5 to 60 minutes. Is preferred.

  The thickness of the hydrophilic photocatalyst film to be formed is preferably in the range of 1 to 500 nm, particularly preferably in the range of 50 to 300 nm. If the hydrophilic photocatalyst film is too thin, the strength may be low, and if it is too thick, cracks may occur.

  The hydrophilic photocatalytic coating of the present invention preferably has a water contact angle of 20 degrees or less (0 to 20 degrees) at room temperature, and preferably 0 to 10 degrees. When the water contact angle exceeds 20 degrees, the antifouling property of the hydrophilic photocatalyst film and the recoatability with respect to the aqueous overcoat liquid may be deteriorated. Furthermore, the hydrophilic photocatalyst film of the present invention has a contact angle with water of 20 degrees or less (0 to 20 degrees), preferably 0 to 10 degrees after being left in a dark place for 1 month. The water contact angle can be measured using a contact angle meter.

  The hydrophilic photocatalyst coating of the present invention preferably has a total light transmittance of 85% or more (85 to 100%), and a haze ratio of preferably 3.5% or less (0 to 3.5%), more preferably 0 to 2.0%. In the case where the total light transmittance is less than 85%, the haze ratio exceeds 3.5%, or both, the hydrophilic photocatalyst film may deteriorate in transparency and impair the appearance. In addition, light transmittance and a haze rate can be measured using a haze meter.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited by these examples.

[Examples 1-3 and Comparative Examples 1 and 2]
A photocatalyst dispersion and a binder mixture were blended with the composition shown in Table 1 to prepare an aqueous dispersion having a total solid concentration of 1.50% by mass and used as a coating solution. In Examples 1 to 3 and Comparative Examples 1 and 2, water was used as a solvent. In addition, the particle size distribution of the photocatalyst fine particles in the obtained coating liquid was measured by Nikkiso Microtrac UPA-EX, and the average particle size of the photocatalyst fine particles was calculated. As a result, the average particle diameter of each of Examples 1 to 3 and Comparative Examples 1 and 2 was 50 nm.
・ Photocatalyst dispersion liquid As a photocatalyst material, a commercially available MPT-623 (trade name, platinum-supported titanium dioxide crystal particles / anatase type, primary particle size of about 20 nm, manufactured by Ishihara Sangyo Co., Ltd.) dispersed in pure water has a solid content concentration of 1.50. A mass% aqueous dispersion was used.
・ POSS
As water-soluble cage silsesquioxane, MS0860 (trade name, tetramethylammonium salt of octaanion cage silsesquioxane having T ³ ₈ structure, ie, R = —O ⁻ N ⁺ (CH ₃ ) ₄ , a cage-type silsesquioxane having a T ³ ₈ structure represented by the above structural formula (1), manufactured by Hybrid Plastics, was used. Hereinafter, this is expressed as POSS (Polyhedral Oligomeric Silsesquioxane).
・ AC-7
As an aqueous solution of the water-soluble zirconium compound, Zircosol AC-7 (trade name, zirconium ammonium carbonate aqueous solution, solid content concentration: 13% by mass, manufactured by Daiichi Rare Elemental Science Co., Ltd.) was used.
・ Snowtex S
As a solid silica sol-based binder, Snowtex S (trade name, colloidal silica having a particle diameter of 8 to 11 nm, manufactured by Nissan Chemical Co., Ltd.) was used.

[Evaluation method of film]
Using the coating liquids prepared in the above Examples and Comparative Examples, sample films were prepared by the following method, and the performance of the coating was evaluated.
-Preparation of sample film A PET (polyethylene terephthalate) film (thickness 50 μm, A4 size (210 mm × 297 mm)) subjected to corona discharge treatment was used as a substrate. The coating solution was applied to one side of the PET film and dried by heating at 90 ° C. for 15 minutes (1 hour for the sample film used for measuring the optical properties) to form the PET film and one side thereof. A sample film consisting of a coating having a thickness of about 200 nm was prepared.
・ Surface tension (static or dynamic)
In order to evaluate the static surface tension, the water contact angle of the coating was measured at room temperature using a contact angle meter CA-A (product name, manufactured by Kyowa Interface Science). The water contact angle was also measured for a sample film left in a dark place for 1 month.
On the other hand, in order to evaluate the dynamic surface tension, the wetting tension of the coating was measured as follows. That is, at room temperature, a wet film test mixture No. 22.6 to No. 73.0 (manufactured by Wako Pure Chemical Industries, Ltd.) was applied to the surface of the film in the sample film with a cotton swab to form a liquid film. It was confirmed whether the liquid film was held without being repelled for 10 seconds. The maximum value of the wet tension corresponding to the liquid mixture for wet tension test in which the liquid film was held was taken as the wet tension (mN / m) of the film. The results are shown in Table 1.
-1 kg load rubbing test A Kim wipe was placed on the coating in the sample film, a 1 kg load was applied to the Kim wipe, the coating was rubbed 10 times, and the presence or absence of scratches on the coating surface was visually confirmed. The results are shown in Table 1.
-Pencil hardness The pencil hardness of the film was measured using a scratch hardness (pencil method) tester (manufactured by Cortec Co., Ltd.) in accordance with JIS K 5600-5-4. The results are shown in Table 1.
・ Appearance (Hue)
The appearance (hue) of the coating was visually confirmed. The results are shown in Table 1.
-Thickness The thickness of the coating was measured using a thin film measuring apparatus F-20 (product name, manufactured by FILMETRICS) and a scanning electron microscope S-3400NX (product name, manufactured by Hitachi High-Technologies). That is, first, it was confirmed that the thickness of the coating was uniform as a whole with the above-mentioned electron microscope, the rough thickness was determined, and then the accurate thickness was determined with the above-mentioned thin film measuring apparatus. The results are shown in Table 1.
Optical characteristics The total light transmittance and haze ratio of the coating were measured using a digital haze meter NDH-20D (manufactured by Nippon Denshoku Industries Co., Ltd.). A 200 nm thick coating in the sample film was used for the measurement. The results are shown in Table 1.
Evaluation Method of Photocatalytic Activity A 1.0 mmol / L aqueous solution of methylene blue was applied on the photocatalyst coating in the sample film and dried at 60 ° C. to adsorb a sufficient amount of methylene blue on the coating surface. Thereafter, the sample film on which methylene blue was adsorbed in this way was irradiated with ultraviolet rays (wavelength: 190 to 400 nm, 1 mW / cm ² ) or visible light (wavelengths 400 to 600 nm, 1 mW / cm ² ), and the photocatalyst evaluation checker PCC- 2 (trade name, manufactured by ULVAC Riko Co., Ltd.), the decrease in the absorbance (wavelength 664 nm) of the blue dye on the methylene blue adsorption surface was measured. The results are shown in Table 1.

※１：光触媒活性は、測定開始10分後のメチレンブルー吸光度の変化量×10³を表す。

* 1: Photocatalytic activity represents the amount of change in methylene blue absorbance × 10 ³ 10 minutes after the start of measurement.

  From the results of Table 1, the composite of Example 1-3 has the best coating properties. From the comparative example, the film formed with only Snowtex or only the water-soluble zirconium compound had insufficient scratch resistance or poor appearance and decreased photocatalytic activity.

Claims (8)

(A) photocatalytic particles,
(B) Water-soluble cage silsesquioxane: 0.01 to 100% by mass with respect to the photocatalyst particles,
(C) Water-soluble zirconium compound: 0.01 to 100% by mass with respect to the photocatalyst particles, and (d) (d1) water and (d2) a hydrophilic film formed of a solvent selected from a mixture of water and alcohol Aqueous photocatalyst coating solution.   2. The coating liquid according to claim 1, wherein the photocatalyst particles are metal oxide crystal particles which are n-type semiconductors. Content of the said photocatalyst particle is 0.01-10 mass% of the whole photocatalyst coating liquid, The coating liquid which concerns on Claim 1 or 2 characterized by the above-mentioned. Coating liquid according to any one of claims 1 to 3, wherein the water-soluble cage silsesquioxane characterized by having a T ³ ₈ structure. Coating liquid according to any one of claims 1 to 4, wherein the water-soluble zirconium compound is ammonium zirconium carbonate solution. The said solvent is water, The coating liquid which concerns on any one of Claims 1-5 . A hydrophilic photocatalyst film comprising a cured product of the coating liquid according to any one of claims 1 to 6 , having a photocatalytic property, and having a water contact angle of 20 degrees or less. 7. Symbol mounting hydrophilic photocatalyst film wherein the cured product is characterized in that it is dried and hardened at a temperature of 50 to 200 degrees.