WO1999041322A1

WO1999041322A1 - Coating material for forming photocatalytic hydrophilic film, method of forming photocatalytic hydrophilic film, and photocatalytic hydrophilic member

Info

Publication number: WO1999041322A1
Application number: PCT/JP1999/000582
Authority: WO
Inventors: Eiichi Kojima
Original assignee: Toto Ltd.
Priority date: 1998-02-10
Filing date: 1999-02-10
Publication date: 1999-08-19
Also published as: AU2546599A

Abstract

A coating material capable of forming a photocatalytic hydrophilic film which is satisfactory in durability, hardness, transparency, and visible light transmittance and retains hydrophilicity for long even when shaded from light. The coating material comprises an amorphous titania precursor, crystalline titania, and a precursor capable of being converted to a compound having a siloxane bond.

Description

Description Coating agent for forming hydrophilic hydrophilic film, method for forming optical hydrophilic film, and luminescent hydrophilic member

[Background of the Invention]

Field of the invention

The present invention relates to a technology for forming a photocatalyst water film, and more particularly, to a coating agent capable of forming a photocatalytic film, a method for forming a photocatalytic hydrophilic film using the same, and a ^ * medium obtained by the method. The present invention relates to a hydrophilic hydrophilic member.

Background art

PCT / WO966 / 93375 discloses that the surface of a photocatalyst-containing layer formed on the surface of a substrate has a high degree of «property (for example, a contact angle with water) according to the« I of the photocatalyst. (Less than 10 °). By utilizing this property, it is said that it is possible to improve the anti-fogging property of transparent members such as glass, lenses, mirrors, etc., and to improve the water-washing property and rain-washing property of the article surface.

The production of organic materials using such a light-based function is performed by preparing a coating liquid containing light or its precursor, applying the coating liquid, and drying or sintering the coating liquid. Was. For example, a titania sol prepared from titanium alkoxide and alcohol amines or _{T i 0 2, Z n 0} , S r T i 0 3 , etc. sol substrate surface the particles prepared by distributed in an aqueous solvent of, Apply to! It is manufactured by sintering. Specifically, a titanium alkoxide is used as a starting material,

Using T i 0 ₂ sol using a T i 0 ₂ sol and S i 0 ₂ sol using a T i 0 ₂ sol and difunctional silicone, using a T i 0 ₂ sol and trifunctional silicone, such as There is a way. Further, in Japanese Laid-9 one 2 4 8 4 6 7 No., a method using a titanium alkoxide and T i 0 ₂ sol is described.

In general, a photocatalytic hydrophilic film is required to have not only high hydrophilicity but also good durability, film hardness and transparency, and high visible transmittance.

To the knowledge of the present inventors, proposals have been made to use as a coating agent a three-component mixture of a non-titania precursor, crystalline titania, and a precursor that can be converted to a compound having a siloxane bond. Not.

[Summary of the Invention]

The present inventors have now found that a coating agent comprising at least three types of amorphous titania precursor, crystalline titania, and a precursor that can be converted into a compound having a siloxane bond, It was found that a ^ K coating with good properties, film hardness, transparency, and visible light transmittance, and that can maintain properties for a long time even under light-shielding conditions can be realized. The present invention is based on this finding.

Accordingly, the present invention is intended for forming a photocatalytic hydrophilic film having good durability, film hardness, transparency, and visible light transmittance, and realizing hydrophilicity that maintains hydrophilicity for a long time even under light shielding conditions. Its purpose is to provide a coating agent.

The coating agent for forming an amphiphilic hydrophilic film according to the present invention comprises at least an amorphous titania precursor, crystalline titania, and a precursor that can be converted into a compound having a siloxane bond. is there. Ming specific explanation]

Coating agent

The hydrophilicity 製造 produced using the coating agent according to the present invention is excellent in durability, film hardness, transparency, and visible light transmittance. In particular, with regard to durability, Sanshi Maintain the hydrophilicity for a long period of time in the key weather meter test (SWM test).

The coating agent for forming a photocatalytic hydrophilic film according to the present invention basically comprises an amorphous titania precursor, crystalline titania, and a precursor that can be converted into a compound having a siloxane bond.

Amorphous titania precursors such as titanium alkoxide are crystallized through heat treatment to form titanium oxide. This titanium oxide is considered to form a dense and strong film by incorporating crystalline titania in addition to the action of exhibiting photocatalytic hydrophilicity. Crystalline titania provides stable and durable hydrophilic hydrophilicity. The precursor that can be converted into a compound having a siloxane bond becomes non-hydrogen by heat treatment or the like, and this silica maintains the hydrophilicity of titanium oxide for a long time even under light-shielding conditions. Works. In addition, precursors that can be converted to compounds having siloxane bonds, if heated simultaneously with the titania-free precursor, may, in some cases, result in highly homogenous T i 0—S i bond bonds, and T i 0 It has been reported that the crystallization of No. ₂ is suppressed and the hydrophilization performance by the photoexcitation of the solvent cannot be sufficiently exhibited (for example, “Catalyst preparation using metal alkoxide, IPC, (1993) , P3 3 7 ”). However, in the present invention, there is no such adverse effect, and a good quality can be realized. Furthermore, due to the presence of the precursor that can be converted into a compound having a siloxane bond, the coating film obtained by the coating agent according to the present invention is light-shielded as compared with the case where a titania-free precursor and crystalline titania are used. It is excellent in that hydrophilicity can be maintained for a long time even under the conditions, and in friction resistance. Further, the coating film obtained by the coating agent according to the present invention is superior in the rub resistance as compared with the case where the non-titanium precursor, crystalline titania and crystalline silica are used. (a) crystalline titania

The crystalline titania used in the present invention may be any of the crystalline systems of anatase, rutile and brookite. In the present invention, crystalline titanium two § is laid force reluctant to be added to the co-one coating agent as stable system not precipitate in the solution, for example, T i 0 ₂ sol suspension dispersed titania microparticles in the solvent Is preferred. Such sols are readily available on the market.

According to a preferred embodiment of the present invention, preferably has an average particle size of T i 0 ₂ sol is 5 0 nm or less, more preferably about 5 to 1 O nm. Use of a sol having such an average particle system is advantageous in that crystalline titania can be stably dispersed in the coating agent, and that the visible light transmittance of the coating film is improved.

According to another preferred embodiment of the present invention, as T i 0 ₂ sol, wide casting of the particle size distribution or average be used those having a particle size peak, wear resistance good good coating, May be advantageous because they can form

The average particle size of the sol can be determined by X-ray diffraction.

(b) Amorphous titania precursor

The precursor of amorphous titania in the present invention means a substance capable of forming crystalline titania by heating, and specifically, an organic titanium compound such as alkoxide, chelate or acetate of titanium, or TiCl ₄ or Ti (S0 ₄₎ means a non-machine titanium compounds such as _2. Further, the titanium alkoxide includes, for example, tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium and the like. Furthermore, a hydrolysis inhibitor such as hydrochloric acid or ethylamine is added to them, and after dilution with an alcohol such as ethanol or propanol, the hydrolysis is allowed to proceed partially or completely. (Partial) hydrolyzate can be obtained Also, in the present invention, it can be used as an amorphous titanium precursor.

According to a preferred embodiment of the present invention, the amount of crystalline titania is preferably such that the total amount of titanium oxide is 6% by weight or more, more preferably 8% by weight or more, and preferably 45% or less. . Further, according to another preferred embodiment of the present invention, the crystalline titania content is preferably 6% by weight or more and 40% by weight or less of the total solid content in the coating agent.

(c) a precursor that can be converted into a compound having a siloxane bond

In the present invention, the “precursor that can be converted into a compound having a siloxane bond” preferably means a substance capable of forming amorphous silica or silicone by film formation. Here, the formation of the precursor into a film means that a hydrolysis reaction, a condensation polymerization reaction, or the like is caused by the action of heating or bandaging, and an amorphous silica or silicone film is formed. In addition, film formation of the precursor also means that when applied to a substrate containing a coating agent containing the precursor and then the solvent component is removed, an amorphous silica film is formed. .

According to a preferred embodiment of the present invention, preferred examples of the precursor that can be converted into a compound having a siloxane bond include a silicic acid precursor that can be converted into amorphous silica by heating, a hydrolyzate thereof, a partial hydrolyzate thereof, The hydrolyzed polycondensate, the partially hydrolyzed polycondensate, or a mixture thereof is exemplified.

Specific examples of the silica precursor that can be converted to amorphous silica by heating include a hydrolyzable silane derivative represented by the following general formula.

R p S 1 4-p

(Where

R is one or more selected from the group consisting of a hydrogen atom and an organic group,

X is one or more selected from the group consisting of an alkoxy group and a nitrogen atom Where p is 1 or 2)

Here, the organic group represented by R is alkyl (more preferably unsubstituted alkyl having 1 to 18 carbon atoms, most preferably alkyl having 3 to 18 carbon atoms) or aryl (preferably phenyl). Means).

Preferred specific examples of the hydrolyzable silane derivative include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, and ethyl tilt. Ributoxy silane, phenyl trimethoxy silane, phenyl triethoxy silane, phenyl tripropoxy silane, phenyl tributoxy silane, dimethyl dimethoxy silane, dimethyl ethoxy silane, dimethyl dipropoxy silane, dimethyl diptoxy silane, getyl dimethoxy silane, ge Tiljetoxysilane, getyldipropoxysilane, getyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyljet Silane, phenylmethyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, 7- Glycidoxypropyltrimethoxysilane, α-methacryloxypropyltrimethoxysilane, 3-chloro mouth propyltrimethoxysilane, octadecyltriethoxysilane, vinyltriethoxyquinsilane, vinylaminopropyl trimethoxysilane, N—) 3

(Aminoethyl) aminaminopropyl trimethoxysilane, amercaptopropyl trimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane and the like.

Further, another preferred silicic acid precursor which can be converted into amorphous silica by heating in the present invention includes partial hydrolysis and Sfck condensation polymerization of the above hydrolyzable silane derivative, or partial hydrolysis of the above hydrolyzable silane derivative. Object and tetramethoxy It is possible to use those prepared by dehydration-condensation polymerization with a partial hydrolyzate such as silane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, or ethoxydimethoxysilane.

The siloxane obtained by the partial hydrolysis / dehydration condensation polymerization is represented by the following average formula.

Average composition formula: R p S 1 Xq O (4-p-q) / 2

(Where

R is as defined above,

X is one or two or more selected from the group consisting of an alkoxy group and a halogen atom;

P is a number that satisfies 0 <p <2, and q is a number that satisfies 0, q, and 4.

Further, another preferred silicic acid precursor which can be converted into silica by heating in the present invention is a tetrafunctional hydrolyzable silane derivative represented by the following formula (^).

S i X ₄

(Where

X is one or more selected from the group consisting of an alkoxy group and a halogen atom)

Preferred specific examples of the tetrafunctional hydrolyzable silane derivative include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, ethoxydimethoxysilane, tetrachlorosilane, tetrabromosilane, silanol, dimethoxydiethoxysilane and the like. Is raised.

Further, other preferred silicic acid precursors which can be converted to silica-free by heating in the present invention include the above-mentioned hydrolysis and dehydration-condensation polymers and partial hydrolysis and dehydration-condensation polymers of the above-mentioned tetrafunctional hydrolyzable silane derivatives. I can give it. The silicate obtained by the above partial hydrolysis / dehydration polycondensation is represented by the following average composition formula.

S i X _q O <4-q) / 2

(Where

q is a number that satisfies 0 x q x 4)

According to a preferred embodiment of the present invention, in terms of the weight of the S i 0 ₂ of the compound precursor that could be converted to compounds having a siloxane bond, wherein the conversion calculated weight of T i 0 ₂ of amorphous titania precursor 5 It is strongly preferable that it is 0% or less.

According to a preferred embodiment of the present invention, the compound having a siloxane bond formed from the silicic acid precursor preferably has a small refractive index. In the case of a transparent substrate, it is advantageous in that a small amount and a high L value of visible light transmittance can be obtained, and in the case of a reflector, a double image can be reduced.

(d) Other ingredients

According to a preferred embodiment of the present invention, the crystalline titania, the amorphous titania precursor, and the precursor that can be converted into a compound having a siloxane bond are preferably dispersed in a solvent to form a coating agent. Specific examples of solvents include alcohols such as methanol, ethanol, i-propanol, n-propanol, i-ptanol, n-ptanol, and ester compounds such as methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate. Is mentioned. When crystalline titania, non-titania precursor, and amorphous titania are dispersed in a form such as a sol, it is a matter of course that the solvent may also function as a solvent for other components.

According to another preferred embodiment of the present invention, the coating agent according to the present invention further comprises, in addition to the above components, a surfactant, an acid, a hydrolysis initiator, a polymerization curing catalyst, a leveling agent, Bacterial metals, platinum group metals, pH adjusters and the like can be included.

The addition of a surfactant offers the advantage that the composition according to the invention can be applied homogeneously to the surface of the component. In a preferred embodiment of the present invention, the surfactant is added in an amount of less than 10 parts by weight, more preferably about 0.1 to 2 fi * parts, per 1 part by weight of the photocatalyst particles. Examples of the surfactant include polyoxyethylene alkyl phenyl sulfonate ammonium sulfonate, sodium polyoxyalkylene phenyl phenyl ether sulfonate, sodium salt of fatty acid, sodium sagegen, Sodium octyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate sodium salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfate sodium salt, Alkyl sulfate TE

A salt, TEA salt of polyoxyethylene alkyl ether sulfate, sodium salt of 2-ethylhexyl alkyl sulfate, sodium sodium acylmethyltaurate, sodium lauroylmethyltaurate, sodium dodelsylbenzenesulfonate, sulfosuccinic acid Anionic surfactants such as disodium lauryl, disodium lauryl polyoxyethylene sulfosuccinate, polycarboxylic acid, oleoyl sarcosine, amide ether sulfate, lauroyl sarcosinate, sulfo FA ester sodium salt and the like; Polyoxyethylene lauryl ether, Polyoxyethylene tridecyl ether, Polyoxyethylene cetyl ether, Polyoxyethylene stearyl ether, Polyoxyethylene oleyl ether, Polyoxye Tylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl phenol ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene alkyl Nyl ether, polyoxyethylene oleate, sorbitan alkyles Ter, polyoxyethylene sorbitan alkyl ester, polyether modified silicone, polyester modified silicone, sorbitan laurate, sorbitan stearate, sorbitan palmitate, sorbitan oleate,

Sorbitan sesquioleate, polyoxyethylene sorbitan laurate, polyoxyeletin sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, glycerol monostearate, polyglycerin fatty acid ester , Alkyl alkyl amide, ethanol laurate, diethanolamide oleate, oxyethylene dodecylamine, polyoxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxy Nonionic surfactants such as ethylene alkyl propylenediamine, polyoxyethylene oxypropylene block polymer, and polyoxyethylene stearate; dimethyl alkyl betaine Amphoteric surfactants such as alkyl glycine, amide betaine and imidazoline, octadecyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, dioleyldimethyl Ammonium chloride, 1-hydroxyethyl 1-2-alkylimidazoline quaternary salt, alkyl isoquinolinium bromide, polymeric amine, octadecyltrimethylammonium chloride, alkyltrimethylammonium chloride, dodecyltrimethyl Ammonium chloride, hexadecyl trimethylammonium chloride, behenyltrimethylammonium chloride, alkylimidazoline quaternary salt, dialkyldimethylammonium chloride O Kutadeshiruamin acetate, tetradecyl § amine acetates, alkyl propylene diene § Min acetate, cationic surfactants such as didecyl dimethyl ammonium Niu skeleton ride, and the like.

According to a preferred embodiment of the present invention, the coating agent according to the present invention comprises an acid Can be. The addition of the acid increases the polarity of the surface to which the coating agent is applied, and can maintain good hydrophilicity even in a dark place. Examples of the acid include nitric acid, sulfuric acid, hydrochloric acid, acetic acid, propionic acid, maleic acid, adipic acid, fumaric acid, phthalic acid, valeric acid, lactic acid, acid, citric acid, and liquor, which have a large ability to impart polarity to the surface. Examples thereof include carboxylic acid, picric acid, formic acid, carbonic acid, and phenol. Particularly, nitric acid, hydrochloric acid and sulfuric acid are preferred.

According to another preferred embodiment of the present invention, the coating agent according to the present invention may include a catalyst for hydrolysis of a silylating component. Due to the presence of this, the hydrolysis of amorphous silica as a precursor is carried out. Examples of preferred catalysts include nitric acid, sulfuric acid, hydrochloric acid, acetic acid, propionic acid, maleic acid, adipic acid, fumaric acid, phthalic acid, valeric acid, lactic acid, butyric acid, citric acid, malic acid having a pH of 2 to 5, Picric acid, formic acid, carbonic acid, phenol and the like.

According to another preferred embodiment of the present invention, when the amorphous silicic acid is a silanol, it can comprise a polymerized hardening medium of silanol. The presence of this catalyst promotes the polymerization reaction of silanol. Preferred examples of ^ include aluminum compounds such as aluminum chelates, aluminum acetylacetonate, aluminum perchlorate, aluminum chloride, aluminum isopoxide, and aluminum isopropoxide; tetraisopropyl titanate And titanium compounds such as tetrabutyl titanate; lithium hydroxide, sodium hydroxide, sodium hydroxide, sodium methylate, sodium acetate, sodium formate, sodium acetate, potassium formate, potassium propionate Basic compounds such as tetramethylammonium chloride and tetramethylammonium hydroxide; n-hexylamine, triptylamine, diazabicyclopentane, ethylenediamine, hexanediamine, diethylenetriamine Min, tetraethylenepentamine, triethylenetetramine, ethanolamines, 7-aminopropyltrimethoxysilane, Amine compounds such as aminopropylmethyldimethoxysilane, 7- (2-aminoethyl) -aminoaminotrimethoxysilane, alpha- (2-aminoethyl) aminopropylmethyldimethoxysilane; tin acetylacetonate, dibutyl Tin compounds such as tin octylate; metal-containing compounds such as cobalt octylate, cobalt acetylacetonate, iron acetyl acetate; phosphoric acid, nitric acid, phthalic acid, p-toluenesulfonic acid, trichloroacetic acid Examples of such acidic conjugates are given below.

Further, according to a preferred embodiment of the present invention, the coating agent according to the present invention can include a repelling agent so that a smooth surface can be formed when applied to the surface of the member. The addition of a leveling agent is particularly advantageous when applying the coating agent according to the invention to large articles. Preferred examples of the leveling agent include diacetone alcohol, ethylene glycol monomethyl ether, 4-hydroxy-1-methyl-2-pentanone, dipropylene glycol, tripropylene glycol, 1-ethoxy-2-propanol, and 1-butanol. 2-propanol, propylene glycol monomethyl ether, 1-propoxy-1-propanol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, and the like. According to a preferred embodiment of the present invention, the coating agent according to the present invention may further comprise an antimicrobial metal (eg, Ag, Cu, Zn) or a compound thereof. By adding these metals, bacteria existing on the surface of the substrate can be killed, and even after the application of the coating agent, the growth of microorganisms such as mold, algae, and moss on the surface can be suppressed. it can.

According to yet another preferred embodiment of the present invention, the coating agent according to the present invention comprises at least a platinum group metal selected from the group consisting of Pt, Pd, Rh, Ru, Os, and Ir. It can comprise one or more. Photocatalyst consisting of metal oxide It has been known that a surface having an antifouling, antibacterial, and deodorizing function based on the action of decomposing light. It is believed that this effect may be maintained even on the surface of the member to which the coating agent according to the present invention has been applied. It is considered that the above-mentioned metal enhances the oxidative decomposition action of the ^] solvent, and improves the antibacterial property, deodorizing property, gas decomposability, organic substance decomposability, etc. of the surface.

The coating agent according to the present invention is preferably weakly acidic, neutral or basic when stored in a tin container or a container made of lining metal, and when applied on a metal member. Particularly when an acid is added as described above, the addition of a pH adjuster is preferred.

Further, the coating agent according to the present invention can appropriately contain an acid or a base in order to improve the dispersibility of the solid component contained therein and to improve the storage stability. Further, in some cases, pigments, dyes, storage stability and the like can be included. Production of photocatalytic hydrophilic coating

Substrates to which the coating agent according to the present invention is applied include glass, ceramics, metals and the like. There are many kinds of glass, such as soda lime glass, quartz glass, non-alkali glass, low expansion glass, and crystal glass. When the base material is ceramics, it is preferable to apply it to those with a glaze layer such as glazed tiles.

If the applicable base material can be expressed in terms of its application, the base material may be: vehicle window glass, general building window glass, skylight, bay window, fixed window, power window, top light, vehicle mirror First, mirrors such as bathroom mirrors, cameras, sensors, cover glasses such as solar cells, and lighting equipment such as fluorescent lamps and light bulbs.

The application of the coating agent according to the present invention to these substrates may be appropriately selected. Examples thereof include spray coating, dip coating, and flow coating. A method such as a spin coating method, a spin coating method, a roll coating method, brush coating, and sponge coating can be suitably used. The application amount may be appropriately determined according to the concentration of the coating agent.

After applying the coating agent according to the present invention to a substrate, the substrate is converted to a precursor having a siloxane bond, which can be converted into amorphous titania precursor crystalline titania and further converted into a compound having a siloxane bond. Conditions. Preferably, the substrate is heated, optionally after drying. That is, at the same time as the amorphous titanium precursor is crystallized, the film having the siloxane bond (preferably, no silica or silicone) adheres to the substrate while taking in the crystalline silicic force. The heating temperature may be appropriately determined within a range in which the coating agent can be fixed, but is generally from 20 to 100 ° C, and preferably has a lower limit of 400 ° C. The upper limit is 800. C, more preferably 600 ° C.

Generally, it is preferable that the heating is performed at a temperature that does not cause the substrate to be heated. Heat may be applied to fix the coating agent while deforming the substrate. For example, in the case of soda-lime glass, if the temperature exceeds 600 ° C., the temperature is preferably changed to 400 ° C. to 600 ° C. However, for example, if a curved mirror is desired to be created, it is possible to heat at a temperature exceeding 600 ° C. and simultaneously deform it thermally. Furthermore, it is also possible to perform heat-strengthening at about 800 ° C. in order to enhance impact resistance.

The higher the heating temperature, the denser the film and the higher the wear resistance. Quartz glass can be heat-treated at a high temperature because it does not thermally deform even at temperatures exceeding 600 ° C. The use of quartz glass makes it possible to obtain a dense and highly wear-resistant film. Is advantageous.

According to a preferred embodiment of the present invention, when glass is used as the base material, especially when soda lime glass or sleeved tile is used, sodium diffusion prevention ihii is provided on the base material, Further, it is preferable to apply a coating agent thereon. When sodium ions migrate from the substrate to the coating layer during heating, they inhibit the formation of crystalline titania. This reduction can be effectively prevented by the sodium diffusion preventing layer. This diffusion prevention layer is preferably formed of silica. Photocatalytic hydrophilic member

The substrate surface to which the coating agent according to the present invention is applied and which is fixed by heating becomes highly hydrophilic. This {τ} property is thought to be due to the photocatalytic action of titania. In other words, it is a property that develops hydrophilicity in response to light and force light excitation. When titania is photo-excited by ultraviolet light, water is hydroxylated by photocatalysis.

It is considered that the surface is chemisorbed in the form of (0Η-), resulting in the surface becoming supersuspendable.

Since the hydrophilic hydrophilicity is excited by a light source having energy equal to or more than the band gap of the photocatalyst, it is preferable that the anatase titania is photoexcited with ultraviolet rays having a wavelength of 387 nm or less and the rutile titania is 413 nm or less. As a suitable ultraviolet light source therefor, an indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp can be used. The substrate outside is excitated by ultraviolet rays contained in sunlight.

The hydrophilized germs have a surface contact angle with water of less than about 10 °, preferably less than about 5 °, especially about 0 °. In general, if photoexcitation is performed with an ultraviolet illuminance of 0.001 mW / cm ² , water can be converted into water within a few days until the contact angle with water becomes approximately 0 °. Since the illuminance of the free Murrell ultraviolet sunlight is about 0. l~l mWZcffl ^2, can be super-hydrophilic surface a more short time if Sarase to sunlight.

Further, due to the high hydrophilicity as described above, the dirt component adhering to the substrate surface can be easily removed by flowing water. Due to this property, it is installed outdoors The resulting substrate has the advantageous property of self-cleaning (self-cleaning) due to rainfall.

Further, the surface of the substrate obtained by the coating agent of the present invention is once highly hydrophilized, and then its hydrophilicity is maintained for a long time even under light shielding or at night. Furthermore, even if the hydrophilic property is lost, the hydrophilic property is restored each time the sheet is exposed to sunlight again.

[Example]

Preparation of coating liquid

Coating liquid 1

S i 0 ₂ film silicon alkoxide solution for forming diluted to a solids concentration of 1% in the first solvent (manufactured by Nippon Soda Co., Ltd.: NS i 5 0 0, a solid part concentration of 5%) and acetic acid Echiru and ethanol 1 did.

Coating liquid 2

T i 0 titanium alkoxide solution for ₂ film (manufactured by Nippon Soda Co., Ltd.: NTD 9 0, a solid part concentration of 5%) and acetic acid Echiru and ethanol 1: diluted to a solid concentration of 0.6% in 1 solvent .

Coating liquid 3

T i 0 ₂ sol and silicon alkoxide hydrolyzate A coating agent for forming a T i 0 ₂ film mixed at a ratio of 0:20 (manufactured by Ishihara Sangyo Co., Ltd .: ST-K 01, solid component) (Concentration 10%) was diluted to a solid concentration of 0.6% with a 1: 1 solvent of ethyl acetate and ethanol.

Coating liquid 4

T i 0 ₂ sol and a silicon alkoxide hydrolyzate 50: 50 copolymer one bets agent to form a T i 0 ₂ film formulated at a ratio of (Ishihara Sangyo Kaisha Ltd.: STK- 0 3, solid The form concentration (10%) was diluted to a solid concentration of 0.6% with a 1: 1 solvent of ethyl acetate and ethanol. Example 1

The formation of the film was performed in a single coat (flow coating). First, an intermediate layer serving as an alkali ion diffusion preventing layer was formed as follows. Coating solution 1 was applied to the surface of a 2 mm thick soda lime glass, and then dried for 10 minutes in a dryer at 120 ° C.

The coating liquid 2 and the coating liquid 3 were mixed at 90:10 and stirred to obtain a hydrophilic film forming coating agent.

After taking out from the dryer and returning to room temperature, apply a hydrophilic film-forming coating agent to the substrate by the same flow coating method, apply the same procedure as above, and then heat at 550 ° C for 30 minutes. By the treatment, the superconductive film of Example 1 was obtained.

Examples 2 and 3 and Comparative Example

The aqueous fiber coatings of Examples 2 and 3 were obtained in the same manner as in Example 1 except that the mixing ratio of the coating liquid 2 and the coating liquid 3 was changed as described in the table below.

Example 4

A superhydrophilic film was obtained in the same manner as in Example 1 except that the coating liquid 3 was used instead of the coating liquid 3, and the ratio was further changed to 70:30.

Performance evaluation test

Evaluation 1: Hydrophilicity evaluation test

After attaching oleic acid to the sample surface, it was washed with a neutral detergent and dried. Thereafter, the sample was irradiated with a black light blue lamp (20 W, manufactured by Sankyo Electric) from a distance of 10 cm, and after 4 hours, the contact angle of the water droplet was determined. The contact angle was evaluated according to the following criteria.

Evaluation A _: Contact angle is less than 8 ° Evaluation B: Contact angle is 8 ° or more and less than 15 °

Evaluation C: Contact angle is 15 ° or more and less than 25 °

Evaluation D: Contact angle 25. Evaluation 2: Maintenance of hydrophilicity in a dark place

As in the case of Evaluation 1, oleic acid was adhered to the sample surface, washed with a neutral detergent, and dried. Thereafter, the sample was irradiated with a black light pull lamp (20 W, Sankyo Denki) from a distance of 10 cm for 4 hours.

After that, it was blocked from UV light and kept in that light-shielded state (dark place) for 3 days. Thereafter, the contact angles were measured. The contact angle was evaluated based on the same criteria as in Evaluation 1. Evaluation 3: Abrasion resistance

The surface of the sample was soaked in a neutral detergent in a sponge scourer and rubbed back and forth 20 times. Then, after washing with water and drying, the degree of damage on the surface was visually observed. The results were evaluated according to the following criteria.

Evaluation A: No change in surface

Evaluation B: No noticeable change

Evaluation C: Slight scratch is observed

Evaluation D: Numerous damages were observed. Evaluation 4: Durability test

A sunshine weather meter test as specified in JISA-14 was performed, and the recovery of hydrophilicity of the sample was examined every 100 hours. Specifically, the sample was irradiated with a black light single lamp (20 W, manufactured by Sankyo Denki) from a distance of 10 cm for one day, and the contact angle after that was measured. Then, evaluate the contact angle according to the same criteria as in Evaluation 1. / 00S82

1 9 Rating 5: Visible light transmittance and haze

The visible light transmittance and haze of the sample were measured using a haze meter manufactured by Gardner Co., Ltd. The above evaluation results are as shown in the following table _c

Coating agent composition (parts by weight) Mixing ratio (weight ratio) Non-crystalline crystalline silica Crystalline titania Crystalline titania Equivalent weight of silica in silica precursor

Titania Titania precursor

Precursor Total titania Coating agent total solids content Titanua equivalent weight in amorphous titania Example 1 90 8 2 8.2 8 2.2 Example 2 80 16 4 16.7 16 5 D Example 3 70 24 6 25.5 24 8.6 Example 4 70 15 15 17.6 15 21.4 Comparative example 70 24 0 25.5 25.5 0

Evaluation 4 Evaluation 5 Evaluation 1 Evaluation 2 Evaluation 3

1 丄 n unuv OK

niri sight haze iK¾ & ouunr ^

Transmittance%% Example 1 A B A A A 8 0 0.2 Example 2 A A B A A A 8 3 0.2 Example 3 A A A A B 8 5 0.2 Example 4 A B A A A 8 4 0.1 Comparative Example A D C

Claims

The scope of the claims

1. A coating agent for forming a photocatalytic hydrophilic film, comprising at least a non-titania precursor, crystalline titania, and a precursor that can be converted into a compound having a siloxane bond.

2. A silica precursor, a hydrolyzate thereof, a partially hydrolyzed product thereof, a hydrolyzed polycondensate thereof, or a partially hydrolyzed precursor which can be converted into amorphous silica by heating when the precursor which can be converted into the compound having a siloxane bond is obtained. The coating agent according to claim 1, wherein the coating agent is a decomposition condensation polymer or a mixture thereof.

3. The coating agent according to claim 1, wherein the amorphous titania precursor is a titanium alkoxide and / or a hydrolyzate thereof.

4. The coating agent according to claim 1, wherein the crystalline titania is a titanium oxide sol.

5. The silicic acid precursor that can become amorphous silica by the heating,

fe:-p S 1 4-p

(Where

X is one or more selected from the group consisting of an alkoxy group and a halogen atom, and p is 1 or 2)

A hydrolyzable silane derivative represented by Average composition formula: R _P S i X _q O ₍ 4-p- _q) / 2

(Where

ρ is a number that satisfies 0 and 2 and q is a number that satisfies 0 and q <4.)

A siloxane represented by

—General formula: S i X ₄

(Where

A tetrafunctional hydrolyzable silane derivative represented by

Average composition formula: S i X _q O (4-q) / 2

(Where

X is one or more selected from the group consisting of an alkoxy group and a halogen atom,

q is a number that satisfies 0 <q <4)

The coating agent according to any one of claims 1 to 3, which is selected from the group consisting of silicates represented by the formula:

6. The coating agent according to any one of claims 1 to 5, wherein the content of the crystalline titania is 6 to 45% by weight of the total amount of titanium oxide.

7. The crystalline titania content is 6 to 40 of the total solid content in the coating agent. The coating agent according to any one of claims 1 to 6,

8. The siloxane bond the compound precursor which can be converted into compounds having the S i 0 ₂ conversion ft * is the equal to or less than 50% of the reduced weight of T i 0 ₂ of amorphous titania precursor, wherein Item 8. The coating agent according to any one of Items 1 to 7.

9. A method for producing a hydrophilic hydrophilic member, comprising applying the coating agent according to any one of claims 1 to 8 to a surface of a substrate, and fixing the coating agent to the surface of the substrate.

10. The method for producing a hydrophilic hydrophilic member according to claim 9, wherein the fixation of the coating agent is performed by heating.

11. The method for producing a photocatalytic hydrophilic member according to claim 10, wherein the heat is applied by heat-treating the surface of the substrate to a temperature of 400 to 800 ° C.

12. The method according to claim 9, wherein the base material is glass.

13. The method for producing a photocatalytic τ member according to claim 12, wherein a sodium diffusion preventing layer is provided on the substrate, and a coating agent is further applied thereon.

14. A photocatalyst water member obtained by the method for producing a photocatalyst water member according to any one of claims 9 to 13, L.