JP2001342430A - Coating liquid for photocatalyst-supporting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating liquid a for photocatalyst-supporting structure, of which coated film is colored for a certain period of time after being coated so that the coated surface and non-coated surface can visually be recognized and then rapidly gets colorless and eventually transparent (not only in the visible light region but also in the ultraviolet region), and to provide a method for producing a photocatalyst-supporting structure using the coating liquid. SOLUTION: This coating liquid is used for forming an adhesion layer composing a photocatalyst-supporting structure composed of the adhesion layer and a photocatalyst layer comprising a photocatalyst laminated on the support in this order, and contains at least one chromic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating solution used for producing a photocatalyst-supporting structure and a method for producing a photocatalyst-supporting structure, and more particularly to an adhesive layer and a photocatalyst layer containing a photocatalyst which are sequentially laminated on a carrier. The present invention relates to a coloring coating solution used for manufacturing a photocatalyst supporting structure and a method for manufacturing a photocatalyst supporting structure using the coating solution.

[0002]

2. Description of the Related Art A photocatalyst carrying a photocatalyst such as titanium oxide of an n-type semiconductor in order to advance various chemical reactions such as decomposition, deodorization, sterilization, purification of water and wastewater treatment by the energy of ultraviolet rays. The structure is well known (JP-A-62-68661, JP-A-2-68190, JP-A-5-309267, etc.). Since this photocatalyst requires a multi-layer coating of an adhesive layer, a catalyst layer, and the like on a carrier having various colors, the coating films are required to be colorless and transparent. However, since such a coating is transparent and has a small thickness, it is difficult to visually discriminate between a coated surface and an uncoated surface. In the case of coating, it is difficult to inspect the coated product, and it is extremely difficult to distinguish between them. As a result, there are problems such as coating leakage, occurrence of a coating group, double coating, and the like, resulting in uneven quality of the coated product and deterioration of work efficiency due to restoration.

On the other hand, conventionally, various methods have been developed for visually identifying uneven coating of a coated product coated with a colorless or light-colored thin film. For example, a method is known in which a fluorescent film is contained in a coating film and the film is illuminated with light such as ultraviolet rays (including ultraviolet rays in sunlight) and the film emits light to recognize the presence of the coating film. (Japanese Unexamined Patent Application Publication No. 2000-51782,
-43787, JP-A-2-24366, JP-A-62-1
477), these emit light only when irradiated with light, and return to the original colorless state when the irradiation is stopped. A method of coloring a coating composition with a water-soluble dye and discoloring the coating by oxidizing the dye with oxygen or ultraviolet rays in the air (JP-A-60-202133). A method of making the coating colorless by volatilization of the acid after the application (Japanese Patent Application Laid-Open No. Sho 60-262874), coloring the coating film with a certain organic dye, and confirming the coating unevenness at the time of coating. A method of discoloring a coating film after a certain period of time by discoloration due to a photochemical reaction or sublimation of a dye or runoff of a dye by rainwater (Japanese Patent Laid-Open No. 25899/1993) is known. However, these are not suitable for a robust coating film in which the photocatalyst permanently absorbs ultraviolet light and performs a catalytic action on the surface of the photocatalyst supporting structure of the present invention. There was no suitable colored coating solution.

[0004]

According to the present invention, the coating film is colored for a certain period after coating, so that the coated surface and the non-coated surface can be visually distinguished from each other. An object of the present invention is to provide a coating solution for a photocatalyst supporting structure, which finally fades and becomes colorless and transparent (transparent not only in the visible region but also in the ultraviolet region), and a method for producing the photocatalyst supporting structure using the coating solution. And

[0005]

An object of the present invention is a coating solution for forming an adhesive layer constituting a photocatalyst-supporting structure comprising a photocatalyst layer including a photocatalyst and an adhesive layer sequentially laminated on a carrier. And a coating liquid for forming an adhesive layer containing at least one chromic material. Still another subject of the present invention is a step of coloring the coating liquid for forming an adhesive layer by applying a physical stimulus or causing a chemical reaction to the coating liquid for forming an adhesive layer. This is a method for producing a photocatalyst-carrying structure, comprising the steps of applying a coating solution to a carrier and applying a coating solution for forming a photocatalyst layer onto an adhesive layer. Still another subject of the present invention is a step of applying the adhesive layer forming coating solution to a carrier, and then coloring the adhesive layer by applying a physical stimulus or causing a chemical reaction to the formed adhesive layer. And a step of applying a coating solution for forming a photocatalyst layer on the adhesive layer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A photocatalyst-supporting structure produced by a coating solution or a production method according to the present invention comprises an adhesive layer and a photocatalyst layer sequentially laminated on a carrier. The coating liquid for forming a photocatalyst layer is coated on the carrier, and the coating liquid for forming a photocatalyst layer is further coated thereon to form a photocatalytic layer. This coating solution for forming an adhesive layer contains at least one chromic material. The chromic material is a concept including any organic molecule that changes its color reversibly by a physical stimulus or a chemical reaction. Here, the physical stimulus means light, heat, pressurization, electric current or a combination thereof, and the chemical reaction means a change in the solvent composition and the like, and the chromic material changes color by these stimuli. Such a chromic material includes a photochromic material whose color changes when stimulated by light, a thermochromic material whose molecular structure changes by a thermal reaction to change its color, an electrochromic material whose color changes by electrochemical oxidation-reduction, and the like. Such changes are reversible, and in the past chromic materials have been required to have an infinite number of repetitions,
In reality, the number of repetitions is finite because side reactions occur in the course of this reversible reaction. In the present invention, unlike the performance conventionally required for the chromic material, it is necessary that this reversible reaction occurs up to a certain number of repetitions, but the smaller the number of repetitions, the more effective,
The number of repetitions is 10 ³ orders or less, or the number of halves is 1
0 is preferably ³ or less.

A photochromic material is a material that changes color upon stimulation with light, and is irradiated with visible light or near visible light to produce photoinduced tautomerism, transition to a triplet state, uniform or non-uniform cleavage, Alternatively, it is colored by a change such as cis-trans isomerization. In the present invention, a photochromic material is preferable among the chromic materials. Such photochromic materials include spiropyrans, fulgides, cyclophanes, diarylethenes, spirooxazines, condensed polycyclic aromatic compounds, photoresponsive liquid crystals, and the like. For the reasons described above, in the present invention, spiropyrans, fulgides, and cyclophanes having a relatively small number of repetitions are preferable, and spiropyrans are more preferable.

[0008] Spiropyrans include 1,3,3-trimethylindolino-6'-nitrobenzopyrrolospirane, 1 ', 3'-dihydro-8-methoxy-1',
3 ', 3'-trimethyl-6-nitrospiro [2H-1
-Benzopyran-2 ', 2'-(2H) -indole], 1,3,3-trimethylindolinobenzopyrrolospirane, 1,3,3-trimethylindolino-6'-
Bromobenzopyrrolospirane, 1,3,3-trimethylindolino-8'-methoxybenzopyrrolospirane,
Examples include 1,3,3-trimethylindolino-β-naphthopyrrolospirane,

Embedded image 1,3,3-trimethylindolino-6′- represented by
Nitrobenzopyrirospirane is preferred.

The fulgides include diphenyl fulgide and triphenyl fulgide. Examples of cyclophanes include anthracene-containing cyclophanes such as anthracenophane, anthracenonaphthalenophane, and anthracenoparacyclophane, and metacyclophane. Examples of the diarylethenes include symmetric diarylethene, asymmetric 2,3-diarylmaleic anhydride,
Unsymmetrical diaryl perfluorocyclopentene and the like can be mentioned. Examples of spirooxazines include spirobenzoxazines, spironaphthoxazines, and spirophenanthoxazines.

The thermochromic material of the present invention includes an electron-donating colorant such as a triphenylmethanephthalide-based or fluoran-based compound;
An alcohol (such as cetyl alcohol), an alkylbenzene (such as dodecylbenzene), and an ester (such as dimethyl alcohol) are combined with a system obtained by combining a compound having an H group with an electron-accepting compound such as a metal salt, a triazole, a carboxylic acid and a salt thereof. And a material in which a third component such as thianylthiopropionate is present. Examples of the electrochromic material of the present invention include rare earth diphthalocyanines such as viologen-based and ruthenium phthalocyanine-based compounds. The content of the chromic material in the coating solution for forming an adhesive layer is preferably 0.001 to 1.0% by weight, and a polar solvent such as alcohols, esters, and ketones can be used as the solvent.

The coating solution for forming an adhesive layer according to the present invention comprises, in addition to the above chromic material, a silicon-modified resin having a silicon content of 2 to 60% by weight and a polysiloxane in an amount of 3 to 60%.
A solution containing 1 to 50% by weight as a resin solid content of a resin containing 5% by weight or a resin containing 5 to 40% by weight of colloidal silica is preferable. Silicon-modified resins such as acryl-silicon resins having a silicon content of less than 2% by weight, resins having a polysiloxane content of less than 3% by weight, and resins having a colloidal silica content of less than 5% by weight have poor adhesion to the photocatalyst layer. In addition, the adhesive layer is deteriorated by the photocatalyst, and the photocatalyst layer is easily peeled. On the other hand, in the case of a silicon-modified resin such as an acryl-silicon resin having a silicon content of more than 60% by weight, the adhesion between the adhesive layer and the carrier is poor, and the hardness of the adhesive layer is low, so that the wear resistance is poor. In the case of a resin having a polysiloxane content of more than 60% by weight or a resin having a colloidal silica content of more than 40% by weight, the adhesive layer becomes porous, or the underlying carrier is deteriorated by a photocatalyst,
In addition, the adhesion between the carrier and the adhesive layer is deteriorated, and the photocatalyst is easily peeled off from the carrier.

When the adhesive layer resin is a silicon-modified resin such as an acryl-silicon resin or an epoxy-silicon resin, the method of introducing silicon into the resin includes a transesterification reaction, a graft reaction using a silicon macromer or a reactive silicon monomer, There are various methods such as a hydrosilylation reaction and a block copolymerization method. In the present invention, a product prepared by any method can be used. As a resin into which silicon is introduced, an acrylic resin or an epoxy resin may be used for film formation, toughness,
Although it is most excellent in terms of adhesiveness to a carrier, it is also possible to use an alkyd resin, a urethane resin, a polyester resin or the like. These resins can be used either in a type dissolved in a solvent or in an emulsion type. There is no problem even if additives such as a crosslinking agent are included.

When the adhesive layer resin contains a polysiloxane, and the polysiloxane is a hydrolyzate of a silicon alkoxide having an alkoxy group having 1 to 5 carbon atoms or a product from the hydrolyzate, the adhesive property and the A supporting structure with improved durability can be obtained. When the carbon number of the alkoxy group of the silicon alkoxide is 6 or more,
Expensive and the hydrolysis rate is very slow,
It becomes difficult to cure in a resin, resulting in poor adhesiveness and durability. Polysiloxane obtained by hydrolyzing silicon alkoxide partially containing chlorine can be used.However, when polysiloxane containing a large amount of chlorine is used, the carrier is corroded by chlorine ions as an impurity, and adhesiveness is deteriorated. Make it worse.

As a method for introducing polysiloxane into a resin, a method in which a silicon alkoxide monomer is mixed with a resin solution and then hydrolyzed with moisture in the air when an adhesive layer is formed, a product obtained by partially hydrolyzing silicon alkoxide in advance. Is mixed with a resin, and further, hydrolysis is performed with moisture in the air at the time of forming a protective film. There are various methods, but any method can be used as long as it can be uniformly mixed with the resin. In order to change the hydrolysis rate of silicon alkoxide, a small amount of an acid or base catalyst may be added. As a resin into which polysiloxane is introduced, acrylic resin, acrylic-silicone resin, epoxy-silicone resin, silicon-modified resin, urethane resin, epoxy resin, polyester resin,
An alkyd resin or the like can be used, but a silicone-modified resin containing an acryl-silicon resin or an epoxy-silicon resin is most excellent in terms of durability.

When the adhesive layer is a resin containing colloidal silica, the particle diameter of the colloidal silica is preferably 10 nm or less. When the thickness is 10 nm or more, not only the resin in the adhesive layer is easily deteriorated by the photocatalyst, but also the adhesion between the photocatalyst layer and the adhesive layer is deteriorated. The simplest method of introducing the colloidal silica into the resin is to mix the resin solution and the colloidal silica solution, and then apply and dry to form an adhesive layer.However, the resin is dispersed in the state where the colloidal silica is dispersed. A polymerized and synthesized product may be applied and dried before use. Further, in order to improve the adhesiveness and dispersibility between the colloidal silica and the resin, the colloidal silica may be treated with a silane coupling agent before use. As the resin into which colloidal silica is introduced, acrylic resin, acrylic-silicone resin, epoxy-silicone resin, silicon-modified resin, urethane resin, epoxy resin,
Examples thereof include a polyester resin and an alkyd resin, and a silicone-modified resin including an acryl-silicon resin and an epoxy-silicon resin is most excellent in terms of durability. As the colloidal silica, any silica sol produced by cation exchange of a sodium silicate solution or silica sol produced by hydrolyzing silicon alkoxide can be used.

For the purpose of suppressing deterioration due to photocatalysis, durability can be improved by mixing a light stabilizer and / or an ultraviolet absorber. As a light stabilizer that can be used, a hindered amine type is preferable, but other substances can also be used. As the ultraviolet absorber, a triazole type or the like can be used. The amount of addition is 0.005 to 10% by weight, preferably 0.01 to 5% by weight, based on the resin. When the surface of the adhesive layer is treated with a silane-based or titanium-based coupling agent, the adhesiveness to the photocatalyst layer may be improved.

As the resin used for the coating liquid for forming the adhesive layer, it is preferable to use the above resin alone or as a mixture. The resin having a solid content of 1 to 50% by weight as an organic solvent solution or an aqueous emulsion is preferably used. It is desirable to use a liquid. With a coating liquid having a resin solids concentration of 1% by weight or less, the adhesive layer becomes too thin and the adhesion of the photocatalyst layer becomes difficult. With a coating liquid having a resin solids content of 50% by weight or more, the adhesive layer becomes too thick. Not only does not result in a good coating film, but also the viscosity becomes too high and handling becomes difficult.

The coating solution for forming a photocatalyst layer according to the present invention contains a photocatalyst, further contains 0.001% to 5% by weight of a silicon compound, and contains a sol of metal oxide and / or hydroxide as a solid component. 0.1 to 30% by weight, and 0.1 to 30% by weight of the photocatalyst powder and / or sol as a solid component. The photocatalyst used in the present invention is in the form of a powder,
Any material, such as a sol or a solution, can be used as long as it adheres to the adhesive layer and shows photocatalytic activity when dried at the drying temperature of the photocatalytic layer. When a sol photocatalyst is used, if the particle diameter is 20 nm or less, preferably 10 nm or less, the transparency of the photocatalyst layer is improved and the linear transmittance is increased. Or when applied to plastic moldings. Further, in the case where a color or pattern is printed on a base carrier, applying such a transparent photocatalyst layer does not impair the base color or pattern.

As the photocatalyst in the photocatalyst layer, TiO ₂ ,
ZnO, SrTiO ₃ , CdS, GaP, InP, Ga
As, BaTiO ₃ , KNbO ₃ , Fe ₂ O ₃ , Ta ₂ O
₅ , WO ₃ , SnO ₂ , Bi ₂ O ₃ , NiO, Cu ₂ O,
SiC, SiO ₂ , MoS ₂ , InPb, RuO ₂ , C
eO _{2 and the} like, and Pt, Rh, R
Metals such as uO ₂ , Nb, Cu, Sn, Ni, and Fe and oxides of these metals can be used. In addition, Pt, Rh, RuO ₂ , Nb, Cu, Sn, Ni,
Any material to which a metal such as Fe is added can be used. The content of the photocatalyst in the coating solution for forming a photocatalyst layer is preferably such that the content of the photocatalyst in the formed photocatalyst layer is 75% by weight or less.

The silicon compound to be added to the coating solution of the photocatalyst layer of the present invention includes a compound represented by the general formula: SiR ¹ _n (OR ² ) _{4-n wherein} R ¹ represents an amino group, a chlorine atom, or a carboxyl group. Represents an alkyl group having 1 to 8 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms or an alkyl group having 1 to 8 carbon atoms substituted with an alkoxy group; Represents any number of 0, 1, 2, and 3. Or a mixture of two or more of the alkoxysilanes represented by the formula [1] or their hydrolysis products. In the above general formula, R1 is a methyl group, an ethyl group, a vinyl group, a γ-glycidoxypropyl group, a γ-methacryloxypropyl group, a γ- (2-aminoethyl) aminopropyl group, a γ-chloropropyl group , Γ
-Mercaptopropyl group, γ-aminopropyl group, γ-
Acryloxypropyl include propyl group, the -OR ^2, methoxy, ethoxy, n- propoxy, i-
Those having a C ₁ -C ₈ alkoxy group such as a propoxy group, an n-butoxy group, a β-memethoxyethoxy group, a β-ethoxyethoxy group, and a 2-ethylhexyloxy group are preferred.
As an example of the silicon compound represented by the above general formula, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and one or a mixture of two or more of their hydrolysis products are preferable. Can be mentioned.

By adding a small amount of the above silicon compound to the coating solution for the photocatalyst layer, a stable coating solution for forming the photocatalyst layer with little increase in viscosity and little sedimentation of the particles can be obtained even after long-term storage. The silicon compound is preferably added in an amount of 0.001 to 5% by weight as a solid content in the coating solution for the photocatalyst layer. If the amount is less than 0.001% by weight, the stability of the coating solution for photocatalyst layer during long-term storage is reduced, and if the amount is more than 5% by weight, the photocatalytic activity is significantly reduced. As a method of adding the silicon compound to the coating solution of the photocatalyst layer, a method of adding the silicon compound to the solution of the photocatalyst powder or sol, or a method of adding the metal oxide and / or hydroxide to the sol solution of the metal oxide and / or hydroxide to be added together with the photocatalyst. Various methods such as a method are possible. Further, a partially hydrolyzed silicon compound may be added. Since the silicon compound added to the coating solution for the photocatalyst layer also has the effect of increasing the adhesion of the photocatalyst layer in boiling water, the amount of the silicon compound added when the above-described silane coupling agent or the like is added is reduced. It is possible to reduce.

The metal oxide gel or hydroxide gel is
It has the effect of fixing the photocatalyst powder and firmly adhering it to the adhesive layer. Since this metal oxide gel or hydroxide gel is porous, it has an adsorptive property and also has an effect of enhancing photocatalytic activity. The content of this metal oxide gel or metal hydroxide gel in the photocatalyst layer is 25 to 95.
% By weight is preferred. If it is less than 25% by weight, adhesion to the adhesive layer will be insufficient, and if it exceeds 95% by weight, the photocatalytic activity will be insufficient. The specific surface area of the metal oxide gel or metal hydroxide gel is preferably 5% after drying at 150 ° C.
When it is 0 m ² / g or more, more preferably 100 m ² / g or more, the adhesion becomes stronger and the catalytic activity is improved.
As metal components, silicon, aluminum, titanium,
Preferable examples include oxide gels or hydroxide gels of metals such as zirconium, magnesium, niobium, tantalum, tungsten, and tin.

[0023] Further, by using an oxide or a hydroxide gel containing two or more kinds of metals selected from silicon, aluminum, titanium, zirconium and niobium as metal components, it is immersed in boiling water. It is possible to enhance the adhesion of the photocatalyst layer later. Examples of combinations of metal components having excellent boiling water resistance include silicon-aluminum, silicon-titanium, silicon-zirconium,
Silicon-niobium, aluminum-titanium, aluminum-zirconium, aluminum-niobium, aluminum-tantalum, titanium-zirconium,
Titanium-niobium, titanium-tantalum, silicon-aluminum-zirconium, silicon-aluminum-titanium and the like are preferred, and silicon-
Examples thereof include oxide gels or hydroxide gels of aluminum, silicon-titanium, silicon-zirconium, silicon-titanium-aluminum, silicon-aluminum-zirconium, and the like.

When the specific surface area of these oxide gels or hydroxide gels is 50 m ² / g or more, the adhesiveness is high,
The catalyst activity is also improved, and it has excellent adhesion even after immersion in boiling water. In actual use, a gel obtained by mixing and drying a sol for forming a gel or a complex oxide gel prepared by a method such as a coprecipitation method may be used. For the composite with the photocatalyst, it is desirable to mix uniformly in the state of the sol before forming the gel, or to mix the raw material before preparing the sol. The method of preparing the gel includes a method of hydrolyzing a metal salt, a method of neutralizing decomposition, a method of ion exchange, a method of hydrolyzing a metal alkoxide, and the like.The photocatalyst powder is uniformly dispersed in the gel. Any method can be used as long as it can be obtained in a state where it is placed. However, if a large amount of impurities are present in the gel, the adhesiveness and catalytic activity of the photocatalyst will be adversely affected. Therefore, a gel with a small amount of impurities is preferred. After maintaining the high catalytic activity by adding a silicon-modified resin or a silane coupling agent to the photocatalyst layer in an amount of 10 to 50% by weight, the photocatalyst layer is immersed in boiling water for 15 minutes.
Excellent adhesion having an evaluation score of 6 or more can be obtained in an adhesion test by a crosscut tape method specified in IS K5400.

The silicon-modified resin or silane coupling agent added to the photocatalyst layer has the effect of increasing the adhesion of the photocatalyst layer in boiling water. As the silicon-modified resin, a commercially available silicon-acrylic or silicone-epoxy resin can be used, and any of those dissolved in a solvent or dispersed in water as an emulsion can be used. is there. As the silane coupling agent, general formulas: RSi (Y) ₃ and (R) ₂ Si
(Y) ₂ (where R represents an organic functional group and Y represents a chlorine atom or an alkoxy group) or the like can be used. In the above general formula, R is a methyl group,
Ethyl group, vinyl group, γ-glycidoxypropyl group, γ
-Methacryloxypropyl group, γ- (2-aminoethyl) aminopropyl group, γ-chloropropyl group, γ-mercaptopropyl group, γ-aminopropyl group, γ-acryloxypropyl group and the like. In addition to atoms, any of C _{1 to} C ₅ alkoxy groups such as methoxy, ethoxy, β-methoxyethoxy, and β-ethoxyethoxy can be used.

The addition amount of the silicon-modified resin or the silane coupling agent is 10 to 5 as a solid content in the photocatalyst layer.
It is desirable to add 0% by weight. If the amount is less than 10% by weight, the adhesion after the boiling water test is reduced, and if the amount is more than 50% by weight, the photocatalytic activity is significantly reduced. As a method of adding a silicon-modified resin or a silane coupling agent to the photocatalyst layer, a method of adding a photocatalyst powder or a sol to a liquid,
Various methods such as a method of adding a metal oxide or hydroxide to a sol solution for forming a metal oxide gel to be added together with the photocatalyst are possible. It is particularly preferable to add an emulsion-type silicon-modified resin to the sol solution, since the adhesion of the photocatalyst layer in boiling water can be significantly increased without substantially reducing the photocatalytic activity. Further, an additive such as a cross-linking agent may be included in the silicon-modified resin or the silane coupling agent.

The metal oxide and / or hydroxide sol in the photocatalyst layer forming coating solution is 0.1 to 30% by weight based on the coating solution as a solid component, and the photocatalyst powder and / or sol is It is desirable to add 0.1 to 30% by weight to the coating solution as a solid component. Metal oxides and / or
Alternatively, the addition of 0.1% by weight or less of the hydroxide sol has a poor function of fixing the photocatalyst to the substrate, and the addition of 30% by weight or more reduces the amount of the photocatalyst powder and / or sol added simultaneously. As a result, the photocatalytic activity decreases. When the amount of the powder and / or sol of the photocatalyst is 0.1% by weight or less, the photocatalytic activity is low. When the amount is 30% by weight or more, the amount of the metal oxide and / or hydroxide sol to be fixed on the substrate. , Which makes it easier to peel.

The coating solution for forming a photocatalyst layer of the present invention may contain various organic coloring agents such as dyes, dyes and pigments. Any of these organic colorants may be of any type because they become colorless by the action of a photocatalyst, such as a nitroso dye, a nitro dye, an azo dye, a stilbene dye, a diphenylmethane dye, a triphenylmethane dye, and a triaryl. Methane dye, xansen dye, acridine dye, quinoline dye, methine dye, polymethine dye,
Examples include thiazole dyes, indamine dyes, indophenol dyes, azine dyes, oxazine dyes, thiazine dyes, sulfur dyes, aminoketone dyes, oxyketone dyes, anthraquinone dyes, indigoid dyes, and phthalocyanine dyes. The content of the organic colorant in the coating solution for forming a photocatalyst layer is preferably 0.001 to 1.0% by weight.

As a method of applying the coating liquid for forming an adhesive layer, a method of coating the coating liquid by a printing method, a sheet forming method, a spray spraying method, a dip coating method, a spin coating method, or the like, and drying it can be used. The drying temperature varies depending on the type of the solvent and the resin, but is generally preferably 150 ° C. or lower. The thickness of the adhesive layer is 0.1μ
If it is not less than m, the photocatalyst layer can be firmly adhered to the photocatalyst supporting structure having high durability. In addition, in the case of a coating method that requires the adhesive layer to be dried and cured in a short time, such as a gravure printing method, a curing agent such as a silicon-based adhesive is used in an amount of 0.1 to the adhesive layer solids according to the required curing speed. -10
Addition by weight is also preferably employed.

The method for applying the coating solution for forming a photocatalyst layer is the same as the method for applying a coating solution for forming an adhesive layer to a suspension in which a photocatalyst is dispersed in a metal oxide sol or metal hydroxide sol solution. It can be coated by a coating method. The photocatalyst may be dispersed in the state of a precursor solution of a metal oxide sol or a metal hydroxide sol, and may be hydrolyzed or neutralized and decomposed at the time of coating to form a sol or a gel. When using a sol, an acid or alkali peptizer may be added for stabilization. In addition, a surfactant or a silane coupling agent of 5% by weight or less with respect to the photocatalyst may be added to the sol suspension to improve adhesion and operability. The drying temperature at the time of forming the photocatalytic layer varies depending on the material of the carrier and the material of the resin in the adhesive layer, but is preferably from 50 ° C to 200 ° C.

As for the thickness of the photocatalytic layer, the thicker the photocatalytic layer, the higher the activity. However, when the thickness is 5 μm or more, it hardly changes. 5μ
When the molecular weight is less than m, the catalyst exhibits high catalytic activity and translucency, so that the catalyst layer is not conspicuous, which is preferable. However, when the thickness is less than 0.1 μm, although the translucency is improved, a high activity cannot be expected because ultraviolet light used by the photocatalyst is transmitted. The thickness of the photocatalyst layer is set to 0.1 μm or more and 5 μm or less, and the photocatalyst particles having a crystal particle diameter of 40 nm or less and a specific surface area of 100 m ² /
When a metal oxide gel or a metal hydroxide gel of g or more is used, the total light transmittance of the photocatalytic layer and the adhesive layer at a total wavelength of 550 nm becomes 70% or more. The structure supported so that the total light transmittance at a wavelength of 550 nm is 70% or more can use transmitted visible light as illumination when the carrier is transparent, and can be used on the carrier even when the carrier is opaque. Since the pattern is not impaired, it is useful in terms of decorativeness.

In order to inspect the applied adhesive layer, the coating liquid for forming the adhesive layer is first colored, and then the coating liquid for forming the adhesive layer is applied to the carrier, or the coating liquid for forming the adhesive layer is applied to the carrier. After application, any method of coloring the formed adhesive layer may be used. The method of coloring the adhesive layer forming coating solution or the adhesive layer may be any of the above-described methods of applying a physical stimulus or a method of causing a chemical reaction, and in particular, when a photochromic material is used, may be irradiated with ultraviolet rays. It is effective, and in this case, the method of ultraviolet irradiation may be any means, but the ultraviolet intensity is 1-2 mW / cm.
It is simple and preferable to use Black Light ² (FL15BL-B manufactured by Matsushita Electric Industrial Co., Ltd.). The adhesive layer applied on the carrier in this way is colored, and it is possible to visually distinguish the surface on which the adhesive layer is formed from the surface on which the adhesive layer is not formed, and then the adhesive layer is quickly and finally Fades and becomes colorless and transparent. Chromic material used in the present invention,
In particular, the photochromic material has a finite number of reversible reactions, and preferably has a number of repetitions of 10 ³ or less, or a half reduction of 10 ³ or less, after which the material loses its ability to absorb ultraviolet light. It becomes transparent not only in the visible region but also in the ultraviolet region.

On the other hand, after the adhesive layer is applied to the carrier, a coating solution for forming a photocatalyst layer is applied on the adhesive layer. If the colorant described above is included in the coating solution for forming a photocatalyst layer, Is colored, and the surface on which the photocatalyst layer is formed and the surface on which the photocatalyst layer is not formed can be visually distinguished. Thereafter, the organic colorant in the photocatalyst layer is finally decomposed by the photocatalyst contained therein, and fades and becomes colorless and transparent (transparent not only in the visible region but also in the ultraviolet region).

[0034]

According to the present invention, when a photocatalyst-supporting structure is manufactured using the coating solution for a photocatalyst-supporting structure of the present invention, the coating film is colored for a certain period after coating, and the coated surface and the uncoated surface are visually distinguished. It is possible to improve the quality of the coated product and to greatly increase the work efficiency of the coating process. Thereafter, the coating film quickly and finally fades and becomes colorless and transparent (transparent not only in the visible region but also in the ultraviolet region), so that the quality of the subsequent photocatalyst-carrying structure does not deteriorate.

[0035]

EXAMPLE 1 An acrylic silicon resin having a silicon content of 3% by weight in terms of oxide (glass transition temperature: 20 ° C.) was an oligomer having a degree of polymerization of 3 to 6 which was a partial hydrolysis product of tetramethoxysilane. The mixture was mixed at a solid content weight ratio of 65:35, diluted with an ethanol-ethyl acetate mixed solvent to a solid content concentration of 10% by weight, and furthermore a photochromic compound, 1,3,3-trimethylindolino-6′-. Nitrobenzopyrrolispirane was mixed at 0.5% by polymerization with respect to the solid content to obtain a coating solution for an adhesive layer. Also, a photocatalytic sol (manufactured by Ishihara Sangyo Co., Ltd., product number: STS-01, solid content concentration 30% by weight, average particle size 7 nm), and colloidal silica (particle size 20 nm) were mixed at a solid content weight ratio of 50:50. , And diluted with ethanol and water to a solid content of 10% by weight to prepare a coating solution for a photocatalyst layer. Next, a film was formed on the glass substrate by brush coating and dried at 120 ° C. for 1 hour to form an adhesive layer having a thickness of 2 μm. When the glass substrate was irradiated with black light (1 mW / cm ² ), the front surface of the glass turned red, and it was confirmed that no adhesive layer was left uncoated. Thereafter, the coating solution for the photocatalyst layer prepared above was applied by a similar brush coating so as to have a dry film thickness of 1 μm, and dried at 60 ° C. for 1 hour to obtain a photocatalyst layer. The resulting sample was red. When this was exposed to sunlight for one day, the color faded and a transparent film was obtained.

Example 2 An adhesive layer and a photocatalyst layer were applied in the same manner as in Example 1 except that a coating solution for a photocatalyst layer further containing 0.05% by weight of methylene blue in solid content was used. By applying the coating solution for forming a photocatalyst layer, the color tone of the film was changed, so that it was confirmed that the photocatalyst layer could be formed without any uncoated portion. When the obtained sample was exposed to sunlight for one week, the colors of the adhesive layer and the photocatalyst layer were faded, and a transparent film was obtained. Comparative Example 1 A solution in which a dye was not mixed with the adhesive layer coating solution in Example 1 was prepared, and an adhesive layer and a photocatalytic layer were formed on a glass substrate under the same conditions. One month after the application, 3% of the adhesive layer was forgotten to be applied by the choking of the photocatalyst layer, and 2% of the photocatalyst layer was forgotten to be applied by the surface contamination.

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Claims (6)

[Claims] 1. A coating solution for forming an adhesive layer constituting a photocatalyst supporting structure comprising an adhesive layer and a photocatalyst layer including a photocatalyst, which is sequentially laminated on a carrier, wherein the adhesive solution contains at least one chromic material. Coating solution for layer formation. 2. The coating solution for forming an adhesive layer according to claim 1, wherein the chromic material is a photochromic material. 3. A resin having a silicon content of 2 to 60% by weight, a resin containing 3 to 60% by weight of polysiloxane, or a resin containing 5 to 40% by weight of colloidal silica as a resin solid content. The coating liquid for forming an adhesive layer according to claim 1, comprising 1 to 50% by weight. 4. A step of coloring the coating liquid for forming an adhesive layer by applying a physical stimulus or causing a chemical reaction to the coating liquid for forming an adhesive layer according to claim 1. And thereafter applying the coating liquid for forming an adhesive layer to a carrier, and applying the coating liquid for forming a photocatalyst layer onto the adhesive layer. 5. The step of applying the coating liquid for forming an adhesive layer according to claim 1 to a carrier, and then applying a physical stimulus to the formed adhesive layer or causing a chemical reaction. Thereby coloring the adhesive layer, and applying a coating solution for forming a photocatalyst layer onto the adhesive layer. 6. The coating solution for forming a photocatalyst layer comprises a silicon compound in an amount of 0.001 to 5% by weight, a metal oxide and / or hydroxide sol in a solid content of 0.1 to 30% by weight,
And the photocatalyst powder and / or sol as a solid content of 0.1.
The method for producing a photocatalyst-supporting structure according to claim 4, wherein the content is 1 to 30% by weight.