JP2011016105A - Photocatalyst coated object, and photocatalyst coating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst coated object capable of obtaining both of photocatalytic decomposition activity and a photocatalytic hydrophilic function even in the case that a photocatalyst coating film is formed on an enamel or clear coating surface in certain thickness in order to suppress the deterioration of the coating surface.SOLUTION: The photocatalyst coated object is constituted by providing a photocatalyst layer on the surface of a base material and the photocatalyst layer is obtained by coating the base material with a photocatalyst coating solution and subsequently drying the coated base material layer. The photocatalyst coating solution includes photocatalytic metal oxide particles, silica particles and a curable silicone emulsion, and the silica particles are partially subjected to coating or modification treatment with silane having a hydrophobic group and/or silicone having a hydrophobic group. The photocatalyst coating solution is applied to the surface of the base material and, after the coated base material is dried, at least a part of the hydrophobic group is substituted with a hydroxy group by the optical excitation reaction of the photocatalytic metal oxide particles to make the surface of the photocatalyst layer hydrophilic.

Description

The present invention relates to a photocatalyst-coated body having a photocatalytic function such as decomposability of harmful gases and self-cleaning properties by rainfall and water washing.
Alternatively, the present invention relates to a photocatalyst coating liquid that can impart a photocatalytic function such as a harmful gas decomposability and a self-cleaning property by rain / water washing to a building, a vehicle, members constituting them, and a composite material by forming a coating layer.

In recent years, photocatalysts such as titanium oxide have been used in many applications such as buildings of buildings, vehicles, members constituting them, and composite materials.
For outdoor use, by applying a photocatalyst to the surface of the base material, it is possible to impart a function of decomposing harmful substances such as NOx and SOx using light energy. Further, if the surface of the layer is made at least hydrophilic when irradiated with light, it is possible to provide a self-cleaning function in which attached dirt is washed away by rain.
In addition, for indoor use, it is possible to impart a function of decomposing toxic substances such as VOCs and an antibacterial function using light energy.

In the case of building structures, vehicles, and members, composite materials, etc., the surface of the base material to which the photocatalytic function is to be applied is enameled or applied on top of the enamel to provide design. Often painted clear.
If an attempt is made to directly form a photocatalyst layer there, the enameled and clear painted surfaces are mainly composed of organic matter, and in the long term, the painted surface will deteriorate due to the photocatalyst particles present at the interface between the photocatalyst layer and the painted surface. Cause problems.

Therefore, conventionally, a barrier layer containing a large amount of inorganic components has been formed between the enamel-coated surface, the clear-coated surface, and the photocatalyst layer (Japanese Patent Laid-Open No. 2007-167718).
However, when the barrier layer is formed, not only the cost is increased, but also man-hours are required and the photocatalytic function cannot be easily provided.

  Therefore, the photocatalytic function is exhibited while suppressing the deterioration of the enameled surface or the clear painted surface, more preferably, there is no off-flavor or environmental pollution during application, and most preferably the deterioration of the substrate surface due to ultraviolet rays is suppressed. A photocatalyst-coated body or a photocatalyst coating solution that directly coats the material to form a photocatalytic functional layer is required.

  As such a photocatalyst coating composition that directly exerts a photocatalytic function on one substrate, the content of silane-modified photocatalyst particles and alkoxy groups and / or hydroxyl groups bonded to silicon atoms is 7 to 20 mmol. An aqueous organic / inorganic composite composition comprising colloidal silica of / g and polymer emulsion particles having an alkoxy group bonded to a silicon atom and / or a hydroxyl group content of 1 to 20 mmol / g is known. (Japanese Unexamined Patent Application Publication No. 2008-222887).

JP 2007-167718 A JP 2008-2222887 A Patent 3985164 JP 2004-51644 A

However, in Japanese Patent Application Laid-Open No. 2008-2222887, photocatalytic degradation activity can be exhibited to some extent, but since the emulsion and silica form an organic / inorganic composite, the hydrophilicity of the photocatalyst is sufficiently affected by the hydrophobic group of the emulsion. I can't show it.
Therefore, in the present invention, in view of the above circumstances, it is possible to obtain both photocatalytic degradation activity and photocatalytic hydrophilic function even when coating with a certain degree of thick film so as to suppress degradation of the enamel coating surface and the clear coating surface. It aims at providing a photocatalyst coating body and a photocatalyst coating liquid.

  That is, the photocatalyst-coated body according to the present invention is a photocatalyst-coated body provided with a photocatalyst layer on a substrate surface, and the photocatalyst layer is obtained by applying a photocatalyst coating liquid and then drying, Comprising photocatalytic metal oxide particles, silica particles, and a curable silicone emulsion, wherein the silica particles are partially coated or modified with a silane having a hydrophobic group and / or a silicone having a hydrophobic group. The silane having the hydrophobic group and / or the silicone having the hydrophobic group are coated with the photocatalyst coating liquid on the surface of the substrate and then dried, and then the photoexcitation reaction of the photocatalytic metal oxide particles is performed. The photocatalyst characterized in that at least a part of the hydrophobic group is substituted with a hydroxyl group so that the surface of the photocatalyst layer becomes hydrophilic. It is a medium-coated body.

  The photocatalytic coating liquid according to the present invention comprises photocatalytic metal oxide particles, silica particles, a curable silicone emulsion, and water, and the silica particles include a silane having a hydrophobic group and / or hydrophobicity. The photocatalyst coating solution is partially coated or modified with a silicone having a group, and the photocatalyst coating solution is applied to a substrate and then dried to form a photocatalyst layer on the substrate surface. A silane having a hydrophobic group and / or a silicone having a hydrophobic group are coated on a substrate and dried, and then at least a part of the hydrophobic group is substituted with a hydroxyl group by a photoexcitation reaction of the photocatalytic metal oxide particles. The photocatalyst coating liquid is characterized in that the layer surface exhibits hydrophilicity.

Photocatalyst-coated body A photocatalyst-coated body according to the present invention is a photocatalyst-coated body having a photocatalyst layer on a surface of a substrate, and the photocatalyst layer is obtained by applying a photocatalyst coating liquid and then drying the photocatalyst coating liquid. , Photocatalytic metal oxide particles, silica particles, and curable silicone emulsion, wherein the silica particles are partially coated or modified with a silane having a hydrophobic group and / or a silicone having a hydrophobic group. The silane having a hydrophobic group and / or the silicone having the hydrophobic group are coated with the photocatalyst coating liquid on the surface of the substrate and then dried, and then by photoexcitation reaction of the photocatalytic metal oxide particles, At least part of the hydrophobic group is substituted with a hydroxyl group so that the surface of the photocatalyst layer becomes hydrophilic. It is a catalyst-coated body.
With this configuration, photocatalytic coating that can obtain both photocatalytic degradation activity and photocatalytic hydrophilic function even when coating with a certain amount of thick film to suppress deterioration of the enameled or clear painted surface The body can be provided.
When photocatalytic coating liquid is applied to a substrate and dried, the photocatalytic metal oxide particles and silica particles have an affinity for water, so that when water diffuses and evaporates on the surface, it easily moves to the surface. . On the other hand, since photocatalytic metal oxide particles and silica particles have an affinity for water, the particles are likely to aggregate with each other, and in particular, silica particles having an excellent affinity for water are prominent.
In the present invention, silica particles are partially coated or modified in advance with a substance having a hydrophobic group. By doing so, aggregation of silica particles can be effectively suppressed.
By using the above silica particles, it is possible to effectively avoid a state where the silica particles block the gap between the silicone emulsions and prevent the photocatalytic metal oxide particles from moving upward. You can concentrate on concentration.
In addition, the aggregation of the silica particles is suppressed and the silica particles are easily moved to the surface, and the photocatalytic metal oxide particles and the silica particles are present at a high concentration on the surface of the photocatalyst layer. Therefore, when the photocatalytic metal oxide particles are irradiated with light having a wavelength at which photocatalytic metal oxide particles are photoexcited after coating and drying, at least a part of the hydrophobic groups on the silica surface is substituted with hydroxyl groups by the oxidation reaction by photoexcitation of the photocatalytic metal oxide particles. . Thereby, not only the photocatalytic decomposition function, but also the substrate surface exhibits a high degree of hydrophilicity, preferably less than 30 °, more preferably less than 20 °, and most preferably less than 10 ° in contact angle with water. The photocatalyst hydrophilic function such as a self-cleaning function by rain and water washing is also exhibited, and it is possible to provide a photocatalyst-coated body capable of obtaining both the photocatalytic decomposition activity and the photocatalytic hydrophilic function.

According to the preferable form of this invention, the said silica particle makes the total amount of the hydroxyl group couple | bonded with the silicon atom, and the alkoxy group smaller than the amount in an untreated silica (6.3 mmol / g). More preferably, it should be less than 6 mmol / g.
By carrying out like this, since aggregation of a silica particle can be suppressed effectively, a silica particle and a photocatalytic metal oxide particle become easy to move upwards. Thereby, the surface of the substrate is preferably less than 30 °, more preferably less than 20 °, and most preferably less than 30 ° in contact angle with water when the photocatalytic metal oxide particles are irradiated with light having a wavelength that photoexcites after coating and drying. Photocatalyst coating that can exhibit both photocatalytic degradation activity and photocatalytic hydrophilic function, as it exhibits a high degree of hydrophilicity of less than 10 °, and also exhibits a photocatalytic hydrophilic function such as a self-cleaning function by rainfall and water washing. The body can be provided.

According to a preferred embodiment of the present invention, the cured product of the curable silicone emulsion contained in the photocatalyst coating liquid is contained in the photocatalyst layer at 85% by mass or more, preferably 90% or more.
Here, the mass of hardened | cured material means the constant value at the time of 105 degreeC drying.
By setting it to 85% or more, both a photocatalytic decomposition activity and a photocatalytic hydrophilic function can be obtained even with a thick film exceeding 2 μm, and a transparent photocatalytic layer can be formed when no colorant is added.
Furthermore, by setting it to 90% or more, both a photocatalytic decomposition activity and a photocatalytic hydrophilic function can be obtained even with a thick film exceeding 5 μm, and a transparent photocatalytic layer can be formed when no colorant is added.

According to a preferred embodiment of the present invention, the film thickness of the photocatalyst layer is more than 2 μm and less than 20 μm, preferably more than 5 μm and less than 20 μm.
By doing so, the influence of the ultraviolet-ray to a base material can be lowered | hung and degradation of the base material by an ultraviolet-ray can be suppressed effectively.

According to a preferred embodiment of the present invention, the average particle size of the curable silicone emulsion is larger than the average particle size of the photocatalytic metal oxide particles and the silica particles.
By doing so, the upward movement of the photocatalytic metal oxide particles and silica particles becomes remarkable.
Therefore, when the silica particles are easy to move upward without being constrained by the silicone emulsion, and when the photocatalytic metal oxide particles are irradiated with light having a wavelength at which the photocatalytic metal oxide particles are photoexcited, the substrate surface has a contact angle with water. Preferably, it exhibits a high degree of hydrophilicity of less than 30 °, more preferably less than 20 °, and most preferably less than 10 °, and also exhibits a photocatalytic hydrophilic function such as a self-cleaning function by rain and water washing. It becomes possible to provide a photocatalyst-coated body capable of obtaining both the decomposition activity and the photocatalytic hydrophilic function.

According to a preferred embodiment of the present invention, the photocatalyst layer is transparent.
By doing so, when the base material is enamel coating or clear coating, a photocatalyst-coated body capable of obtaining both photocatalytic degradation activity and photocatalytic hydrophilic function even with a thick film exceeding 2 μm while effectively utilizing its design properties It is easier to provide.

  Here, as the degree of “transparency”, it is more preferable to secure the linear transmittance of the photocatalyst layer at a wavelength of 550 nm of 70% or more, more preferably 80% or more. By doing so, it becomes possible to express without impairing the color and design of the groundwork. Moreover, even if it is coated on highly transparent glass or plastic, the transparency is not impaired.

  According to a preferred embodiment of the present invention, the photocatalytic metal oxide particles include anatase type titanium oxide, rutile type titanium oxide, brookite type titanium oxide, tin oxide, zinc oxide, strontium titanate, tungsten oxide and cerium oxide. Particles of various metal oxides, particles obtained by combining a plurality of these particles, particles obtained by combining or doping these particles with a metal such as copper, platinum, iron, palladium, silver, and gold, and the surface of these particles. Particles partially coated and modified with silane, silicone, or hydrolyzable metal salt can be suitably used.

In the present invention, the photoexcitation reaction of the photocatalytic metal oxide particles refers to irradiating the photocatalytic metal oxide particles with light having a wavelength equal to or less than the wavelength corresponding to the band gap energy of the photocatalytic metal oxide particles.
As a light source having such a wavelength, for example, sunlight can be suitably used outdoors.

  According to a preferred embodiment of the present invention, the photocatalytic metal oxide particles preferably have an average particle size of 10 nm or more and less than 100 nm, more preferably 10 nm or more and 60 nm or less. The average particle diameter is calculated as a number average value obtained by measuring the length of any 100 particles that enter a 200,000-fold field of view with a scanning electron microscope.

  As the shape of the particle, a true sphere is the best, but it may be approximately circular or elliptical, and the length of the particle in this case is approximately calculated as ((major axis + minor axis) / 2). Within this range, weather resistance, harmful gas decomposability, and various desired coating properties (transparency, coating strength, etc.) are efficiently exhibited.

  According to a preferred embodiment of the present invention, the photocatalyst particles preferably have an average crystallite diameter of 3 nm or more and less than 30 nm, more preferably 5 nm or more and 20 nm or less. The average particle diameter is calculated by the Scherrer equation from the integral width of the three strong lines of the X-ray profile obtained by the powder X-ray diffraction method.

  According to a preferred embodiment of the present invention, the content of the photocatalyst particles is a dry mass (solid content mass) of 0. 0 to the total mass of the curable silicone emulsion, the photocatalytic metal oxide particles, and the silica particles. It is more than 1% by mass and less than 15% by mass, more preferably more than 0.5% by mass and less than 5% by mass. By making it within the above range, it is possible to effectively exhibit the decomposition function of the photocatalyst and to improve the weather resistance of the base material and the intermediate layer to such an extent that it can withstand long-term use in the tropics and the like. It is also possible to suppress deterioration of the base material and the intermediate layer due to. That is, it is possible to simultaneously exhibit an ultraviolet absorption function in the photocatalyst layer and an excellent photocatalyst function under sunlight irradiation in the temperate and subarctic regions and sufficient weather resistance.

  According to a preferred embodiment of the present invention, the silica particles preferably have an average particle size of more than 10 nm and 200 nm or less, more preferably more than 20 nm and 100 nm or less. The average particle diameter is calculated as a number average value obtained by measuring the length of any 100 particles that enter a 200,000-fold field of view with a scanning electron microscope. As the shape of the particle, a true sphere is the best, but it may be approximately circular or elliptical, and the length of the particle in this case is approximately calculated as ((major axis + minor axis) / 2).

  According to a preferred embodiment of the present invention, the degree of hydrophobicity of the silica particles is such that the total amount of hydroxyl groups and alkoxy groups bonded to silicon atoms in the silica particles is smaller than that in the untreated state (6.3 mmol / g). Preferably it is less than 6 mmol / g.

As a substance having a hydrophobic group for partially coating or modifying silica particles used in the present invention, a photocatalytic coating liquid is applied to the surface of the substrate and dried, and then photoexcitation reaction of photocatalytic metal oxide particles is performed. Accordingly, at least a part of the hydrophobic group is substituted with a hydroxyl group, and the surface of the photocatalyst layer becomes hydrophilic. This is a silane or silicone having a hydrophobic group. For example, 1-3 functional silane, silicone, etc. can be used suitably.
The amount of the substance used for the coating or modification treatment in the silica particles made of the substance having a hydrophobic group is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass with respect to the amount of silica.

    Examples of the silane having a hydrophobic group used in the present invention include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrisilane. Methoxysilane, isopropyltriethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, n-heptyltrimethoxysilane, n-octyltrimethoxysilane, Vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltrie Xysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-aminopropyltrimethoxy Silane, 3-aminopropyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanate pro Rutriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl Triethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloyloxypropyltri-n-propoxysilane, 3- (meth) acryloyloxy Trialkoxysilanes such as propyltriisopropoxysilane, 3-ureidopropyltrimethoxysilane, and 3-ureidopropyltriethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, and diethyl Rudiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n -Pentyldimethoxysilane, di-n-pentyldiethoxysilane, di-n-hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyldimethoxysilane, di-n-heptyldiethoxysilane, di- n-octyldimethoxysilane, di-n-octyldiethoxysilane, di-n-cyclohexyldimethoxysilane, di-n-cyclohexyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3- (meth) acryloyloxypropylmethyl Dialkoxysilane such as dimethoxysilane; trimethylmethoxysilane, monoalkoxysilane such as trimethyl silane, and the like. Moreover, these can be used individually or in mixture of 2 or more types.

  As the silicone having a hydrophobic group used in the present invention, a (partial) hydrolysis / condensation product of the above silane can be suitably used.

The curable silicone emulsion refers to a silicone emulsion that, when applied to a substrate and dried, causes a curing polymerization reaction due to a functional group present in the silicone emulsion, thereby forming a cured film.
Here, a hydrolysis / condensation reaction, a photopolymerization reaction, or the like can be suitably used for the curing reaction.
When the curing reaction is a hydrolysis / condensation reaction, a curable silicone emulsion having an alkoxide group as a functional group and generating a siloxane bond by the hydrolysis / condensation reaction can be suitably used.

In the curable silicone emulsion, in addition to the functional group causing the curing reaction, there is an organic cross-linked portion by emulsion polymerization.
As the organic crosslinking part, a crosslinking part produced by radical polymerization such as an ethylene crosslinking part in which a vinyl group and a vinyl group are polymerized can be suitably used. As long as it is a crosslinked part produced by radical polymerization, it is not particularly limited to a hydrocarbon group, and a combination of various modifying groups can be suitably used.

  In the curable silicone emulsion, an organic group bonded to a silicon atom may be present in addition to the functional group causing the curing reaction and the organic cross-linking portion. Here, examples of the organic group include hydrocarbon groups such as an alkyl group, a phenyl group, and a cycloalkyl group, and organic groups in which a part of the hydrogen is substituted with a modifying group. Here, as the modifying group, an amino group, a carboxyl group, a mercapto group, an acrylic group, an epoxy group, or the like can be suitably used.

  Next, the surfactant used as an emulsifier for the emulsion will be described. As the surfactant, conventionally known nonionic, cationic, and anionic surfactants and reactive emulsifiers containing functional groups capable of radical polymerization can be applied. Furthermore, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene carboxylic acid ester, sorbitan ester, polyoxyethylene sorbitan ester, and cations such as alkyltrimethylammonium chloride and alkylbenzylammonium chloride Surfactants, alkyl or alkyl allyl sulfates, anionic surfactants such as alkyl or alkyl allyl sulfonates, dialkyl sulphosuccinates, zwitterionic surfactants such as amino acid types and betaine types, Radically polymerizable (meth) acrylate containing a group such as sulfonate, polyoxyethylene chain, quaternary ammonium salt in the molecule described in JP-A-8-27347, Styrene, can exhibit various reactive surfactants containing derivatives such as maleic acid ester compound.

  These surfactants may be used alone or in combination of two or more. The surfactant is preferably used in an amount of 0.5 to 15% by weight, particularly 1 to 10% by weight, based on the resin solid content in the emulsion.

  In the present invention, the photocatalyst layer may contain inorganic oxide particles other than silica particles. The inorganic oxide particles are not particularly limited as long as they are inorganic oxide particles capable of forming a layer together with the photocatalyst particles, and any kind of inorganic oxide particles can be used. Examples of such inorganic oxide particles include alumina, zirconia, ceria, yttria, tin oxide, iron oxide, manganese oxide, nickel oxide, cobalt oxide, hafnia and other single oxide particles; and barium titanate, Examples thereof include composite oxide particles such as calcium silicate, aluminum borate, and potassium titanate.

  According to a preferred embodiment of the present invention, at least one selected from the group consisting of vanadium, iron, cobalt, nickel, palladium, zinc, ruthenium, rhodium, copper, silver, platinum and gold is used to develop higher photocatalytic ability. These metals and / or metal compounds comprising these metals may be added. This addition can be performed by any method such as a method in which the metal or metal compound is mixed and dissolved or dispersed in a coating solution, or a method in which the metal or metal compound is supported on a photocatalyst layer or photocatalyst particles.

  You may mix | blend a ultraviolet absorber in a photocatalyst layer. The content of the ultraviolet absorber is not limited as long as the weather resistance can be improved without inhibiting the expression of the photocatalytic activity. For example, 0.001 to 10% by mass, preferably 0.01 to 10% by weight in the photocatalyst layer. It is preferable to contain 5 mass%.

  Preferred examples of the ultraviolet absorber that can be used in the present invention include benzophenone-based, benzotriazole-based, and triazine-based ultraviolet absorbers.

  In particular, a triazine ultraviolet absorber is preferable because it is chemically stable. Specifically, hydroxyphenyltriazine or a derivative thereof can be suitably used as the triazine-based ultraviolet absorber.

  Specific examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and 2-hydroxy-4. -N-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2,2 ' -Dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy- 4-methoxy-2'- Ruboxybenzophenone, 2-hydroxy-4-stearyloxybenzophenone, octabenzone, and 2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4-methacryloxybenzophenone, 2-hydroxy-5-acryloxybenzophenone, 2-hydroxy -5-methacryloxybenzophenone, 2-hydroxy-4- (acryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-diethoxy) benzophenone, 2-hydroxy- Examples thereof include polymerizable benzophenone-based ultraviolet absorbers such as 4- (acryloxy-triethoxy) benzophenone and (co) polymers thereof.

  Specific examples of the benzotriazole-based UV absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-5′-tert-butylphenyl) benzo. Triazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy- 3,5-di-tert-octylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α′-dimethylbenzyl) phenyl] benzotriazole), methyl-3- [3 -Tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate Condensate with polyethylene glycol (molecular weight 300) (product name: TINUVIN-1130 manufactured by Ciba Geigy Co., Ltd.), isooctyl-3- [3- (2H-benzotriazol-2-yl) -5-tert-butyl- 4-hydroxyphenyl] propionate (manufactured by Ciba Geigy Japan, product name: TINUVIN-384), 2- (3-dodecyl-5-methyl-2-hydroxyphenyl) benzotriazole (manufactured by Ciba Geigy Japan, product name) : TINUVIN-571), 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-) tert-amylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphe) ) Benzotriazole, 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2-methylenebis [4 -(1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -4,6-bis (1 -Methyl-1-phenylethyl) phenol (manufactured by Ciba Geigy Japan, product name: TINUVIN-900), and 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (Otsuka Chemical) Product name: RUVA-93), 2- (2′-hydroxy-5′-methacryloxyethyl-3-tert-butylphenyl) -2H Benzotriazole, 2- (2′-hydroxy-5′-methacrylyloxypropyl-3-tert-butylphenyl) -5-chloro-2H-benzotriazole, 3-methacryloyl-2-hydroxypropyl-3- [3 ′ Polymerizable benzotriazole ultraviolet absorbers such as-(2 "-benzotriazolyl) -4-hydroxy-5-tert-butyl] phenylpropionate (manufactured by Ciba-Geigy Japan, product name: CGL-104) And TINUVIN-384-2 (product name, manufactured by Ciba-Geigy Corporation of Japan), TINUVIN-99-2 (product name, manufactured by Ciba-Geigy Corporation of Japan), TINUVIN-109 (product) Name, manufactured by Nippon Ciba-Geigy Corp.), TINUVIN-328 (product name, manufactured by Ciba-Geigy Corp. Japan), INUVIN-928 (product name, manufactured by Nihon Ciba-Geigy Corporation), and the like.

  Further, in the photocatalyst layer of the present invention, those further containing a hindered amine-based and / or hindered phenol-based light stabilizer, the photocatalyst layer of the present invention has excellent weather resistance due to a synergistic effect with the ultraviolet absorber. In view of light resistance, it is preferable.

  In particular, according to a preferred embodiment of the present invention, a hydroxyphenyl triazine compound may be blended as an ultraviolet absorber and a hindered amine compound as a light stabilizer. By doing so, the absorption performance of ultraviolet rays having a short wavelength of less than 380 nm by the photocatalyst layer is stabilized.

The content of the light stabilizer in the photocatalyst layer of the present invention is not limited as long as the weather resistance can be improved without inhibiting the expression of photocatalytic activity, but for example 0.001 to 10% by mass in the photocatalyst layer, It is preferable to contain 0.01-5 mass% preferably.
Specific examples of the hindered amine light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (2,2,6,6-tetramethylpiperidyl) sebacate, bis (1, 2,2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, 1- [2- [3- (3 5-Di-tert-butyl-4-hydroxyphenyl) propynyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propynyloxy] -2,2,6 6-tetramethylpiperidine, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl-sebake Mixture (manufactured by Ciba Geigy Japan, product name: TINUVIN-292), bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, TINUVIN-123 (product name, Japan) Ciba-Geigy Co., Ltd.), TINUVIN-111FDL (product name, manufactured by Nippon Ciba-Geigy Co., Ltd.), TINUVIN 292 (product name, manufactured by Ciba-Geigy Japan), and 1,2,2,6,6-pentamethyl-4- Piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl Acrylate, 1,2,2,6,6-pentamethyl-4-iminopiperidyl methacrylate, 2,2,6 6, -tetramethyl-4-iminopiperidyl methacrylate, 4-cyano-2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-cyano-1,2,2,6,6-pentamethyl-4- Examples thereof include polymerizable hindered amine ultraviolet absorbers such as piperidyl methacrylate and (co) polymers thereof.

  Specific examples of the hindered phenol light stabilizer include bis (3,5-tert-butyl) -4-hydroxytoluene, TINUVIN-144 (product name, manufactured by Ciba Geigy Japan, Inc.), and the like. it can.

As an optional component, the photocatalyst coating liquid may contain a surfactant in the coating liquid in addition to the emulsion emulsifier.
In a preferred embodiment of the present invention, the surfactant is preferably added in an amount of less than 10 parts by weight, more preferably about 0.1 to 2 parts by weight with respect to 1 part by weight of the photocatalyst particles.

  Examples of surfactants that can be added to the photocatalyst coating liquid according to the present invention include sulfonic acid polyoxyethylene alkylphenyl ether ammonium salt, sulfonic acid polyoxyethylene alkylphenyl ether sodium salt, fatty acid sodium soap, fatty acid potassium soap, dioctyl sulfosuccinate. Sodium acid, alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate soda salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfate soda salt, alkyl sulfate TEA salt, polyoxyethylene alkyl ether sulfate TEA salt 2-ethylhexyl alkyl sulfate sodium salt, acylmethyl taurate sodium , Sodium lauroylmethyl taurate, sodium dodecylbenzene sulfonate, disodium lauryl sulfosuccinate, disodium lauryl polyoxyethylene sulfosuccinate, polycarboxylic acid, oleoyl sarcosine, amide ether sulfate, lauroyl sarcosinate, sulfo FA ester Anionic surfactant such as sodium salt; polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethylene Alkyl ester, polyoxyethylene alkylphenol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Xylethylene octyl phenyl ether, polyoxyethylene laurate, polyoxyethylene stearate, polyoxyethylene alkyl phenyl ether, polyoxyethylene oleate, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, polyether modified silicone, polyester modified silicone Sorbitan laurate, sorbitan stearate, sorbitan palmitate, sorbitan oleate, sorbitan sesquioleate, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, Glycerol stearate, polyglycerin fatty acid ester, alkylalkylol Lauric acid diethanolamide, oleic acid diethanolamide, oxyethylene dodecylamine, polyoxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxyethylene alkylpropylenediamine, polyoxyethyleneoxypropylene block polymer, Nonionic surfactants such as polyoxyethylene stearate; amphoteric surfactants such as dimethylalkylbetaine, alkylglycine, amidebetaine, imidazoline, octadecyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium chloride, tetradecylmethylbenzylammonium chloride, Dioleyldimethylammonium chloride, 1-hydroxyethyl-2- Rukiruimidazoline quaternary salt, alkylisoquinolinium bromide, polymeric amine, octadecyltrimethylammonium chloride, alkyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkylimidazoline quaternary salt, dialkyl And cationic surfactants such as dimethylammonium chloride, octadecylamine acetate, tetradecylamine acetate, alkylpropylenediamine acetate, and didecyldimethylammonium chloride.

  An organic antifungal agent may be blended in the photocatalyst layer. Examples include organic nitrogen sulfur compounds, pyrithione compounds, organic iodine compounds, triazine compounds, isothiazoline compounds, imidazole compounds, pyridine compounds, nitrile compounds, thiocarbamate compounds, thiazole compounds, and organic iodine. Compounds and disulfide compounds may be mentioned and used alone or as a mixture. Since many antifungal agents generally have an effect of preventing algae, addition of the antifungal agent can be expected to suppress both mold and algae.

Photocatalyst coating liquid The photocatalyst coating liquid according to the present invention comprises photocatalytic metal oxide particles, silica particles, a curable silicone emulsion, and water, and the silica particles include a silane having a hydrophobic group and / or a hydrophobic group. The photocatalyst coating solution is partially coated or modified with silicone having a functional group, and the photocatalyst coating solution is applied to a substrate and dried to form a photocatalyst layer on the substrate surface. The silane having a hydrophobic group and / or the silicone having a hydrophobic group are coated on a substrate and dried, and then at least a part of the hydrophobic group is substituted with a hydroxyl group by a photoexcitation reaction of the photocatalytic metal oxide particles. Thus, the photocatalyst coating liquid is characterized in that the surface of the layer becomes hydrophilic.
With this configuration, photocatalytic coating that can obtain both photocatalytic degradation activity and photocatalytic hydrophilic function even when coating with a certain amount of thick film to suppress deterioration of the enameled or clear painted surface The body can be provided.
When photocatalytic coating liquid is applied to a substrate and dried, the photocatalytic metal oxide particles and silica particles have an affinity for water, so that when water diffuses and evaporates on the surface, it easily moves to the surface. . On the other hand, since photocatalytic metal oxide particles and silica particles have an affinity for water, the particles are likely to aggregate with each other, and in particular, silica particles having an excellent affinity for water are prominent.
In the present invention, silica particles are partially coated or modified in advance with a substance having a hydrophobic group. By doing so, aggregation of silica particles can be effectively suppressed.
By using the above silica particles, it is possible to effectively avoid a state where the silica particles block the gap between the silicone emulsions and prevent the photocatalytic metal oxide particles from moving upward. You can concentrate on concentration.
In addition, the aggregation of the silica particles is suppressed and the silica particles are easily moved to the surface, and the photocatalytic metal oxide particles and the silica particles are present at a high concentration on the surface of the photocatalyst layer. Therefore, when the photocatalytic metal oxide particles are irradiated with light having a wavelength at which photocatalytic metal oxide particles are photoexcited after coating and drying, at least a part of the hydrophobic groups on the silica surface is substituted with hydroxyl groups by the oxidation reaction by photoexcitation of the photocatalytic metal oxide particles. . Thereby, not only the photocatalytic decomposition function, but also the substrate surface exhibits a high degree of hydrophilicity, preferably less than 30 °, more preferably less than 20 °, and most preferably less than 10 ° in contact angle with water. The photocatalyst hydrophilic function such as a self-cleaning function by rain and water washing is also exhibited, and it is possible to provide a photocatalyst-coated body capable of obtaining both the photocatalytic decomposition activity and the photocatalytic hydrophilic function.

According to a preferred embodiment of the present invention, the cured product of the curable silicone emulsion contained in the photocatalyst coating solution is 85% by mass or more, preferably 90% by mass or more, based on the dried product of the photocatalyst coating solution. Like that.
Here, the mass of hardened | cured material means the constant value at the time of 105 degreeC drying.
By setting it to 85% or more, both a photocatalytic decomposition activity and a photocatalytic hydrophilic function can be obtained even with a thick film exceeding 2 μm, and a transparent photocatalytic layer can be formed when no colorant is added.
Furthermore, by setting it to 90% or more, both a photocatalytic decomposition activity and a photocatalytic hydrophilic function can be obtained even with a thick film exceeding 5 μm, and a transparent photocatalytic layer can be formed when no colorant is added.

According to a preferred embodiment of the present invention, the film thickness of the photocatalyst layer is more than 2 μm and less than 20 μm, preferably more than 5 μm and less than 20 μm.
By doing so, the influence of the ultraviolet-ray to a base material can be lowered | hung and degradation of the base material by an ultraviolet-ray can be suppressed effectively.

According to a preferred embodiment of the present invention, the average particle size of the curable silicone emulsion is larger than the average particle size of the photocatalytic metal oxide particles and the silica particles.
By doing so, the upward movement of the photocatalytic metal oxide particles and silica particles becomes remarkable.
Therefore, when the silica particles are easy to move upward without being constrained by the silicone emulsion, and when the photocatalytic metal oxide particles are irradiated with light having a wavelength at which the photocatalytic metal oxide particles are photoexcited, the substrate surface has a contact angle with water. Preferably, it exhibits a high degree of hydrophilicity of less than 30 °, more preferably less than 20 °, and most preferably less than 10 °, and also exhibits a photocatalytic hydrophilic function such as a self-cleaning function by rain and water washing. It becomes possible to provide a photocatalyst-coated body capable of obtaining both the decomposition activity and the photocatalytic hydrophilic function.

The photocatalyst coating liquid is not limited to the following, in addition to the above “photocatalyst particles”, “silica particles”, “curable silicone emulsion”, “inorganic oxide particles other than silica particles”, “metal or metal compound”, “Ultraviolet absorber”, “light stabilizer”, “surfactant”, “organic antifungal agent” and the like can be blended.
Items related to “photocatalyst particles”, “silica particles”, “curable silicone emulsion”, “containing inorganic oxide particles other than silica particles”, “addition of metal or metal compound”, “formulation of UV absorber” As for “formulation of light stabilizer”, “formulation of surfactant”, and “formulation of anti-algae agent”, all the contents described in the section of “photocatalyst-coated body” can be preferably used.

  In the photocatalyst coating liquid of the present invention, a film forming aid having a boiling point of 100 ° C. or higher that is soluble in water or can be uniformly dispersed in water can be blended. This film-forming aid remains in the film even after most of the water has evaporated, and it provides fluidity to the film until it is completely cured, thereby repairing the film that was rough at the time of vaporization. It is given. In order to obtain a good film, the non-reactive film-forming aid must eventually disappear from the cured film, and does not contain hydroxyl groups that can be bonded to silicon atoms by transesterification. It is preferable. Therefore, the film forming aid is preferably an organic solvent having a boiling point of 100 ° C. or higher, preferably 100 to 250 ° C., particularly 100 to 200 ° C. If the boiling point is too high, it may easily remain in the film. Specifically, alcohols such as 1-butanol, isobutyl alcohol, 2-pentanol, 3-pentanol, isopentyl alcohol, methyl lactate, ethyl lactate, and 3-methyl-3-methoxybutanol, 1,2-propane Polyols such as diol, 1,3-butanediol 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, glycerin, trimethylolpropane, Ethylene glycol derivatives such as 2-butoxyethanol, 2-phenoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, diethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-methoxy-2 Propylene glycol derivatives such as methyl ethyl acetate, 1-ethoxy-2-methyl ethyl acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monomethyl ether acetate, 3-methoxybutyl Examples include butylene glycol derivatives such as acetate, ketones such as cyclohexanone, esters such as butyl acetate, isobutyl acetate, γ-butyrolactone, propylene carbonate, and dibutyl phthalate. In particular, alkylene glycol derivatives such as 2-ethoxyethyl acetate, 2-butoxyethyl acetate, diethylene glycol monobutyl ether acetate, 1-ethoxy-2-methylethyl acetate, dipropylene glycol monomethyl ether acetate are leveling properties. To preferred. Since these organic solvents are inferior in water solubility as compared with low boiling alcohols such as methanol and ethanol, they do not impair the stability of the emulsion and contribute only to the formation of a uniform film.

  The amount of the film forming aid added is preferably 0 to 20 parts by weight, particularly 1 to 15 parts by weight, based on 100 parts by weight of the silicone resin. If added in excess of 20 parts by weight, the amount of the film-forming aid remaining in the film after the curing is increased, and the film characteristics may be insufficient.

  The solvent of the photocatalyst coating liquid of the present invention is mainly water. As a result, it is possible to effectively prevent the odor and environmental pollution associated with the volatilization and evaporation of organic substances during coating film formation.

  Moreover, the solid content concentration of the photocatalyst coating liquid is not particularly limited, but it is preferably 10 to 60% by mass in terms of easy application. Photocatalyst coating liquid In addition, the components of the photocatalyst coating liquid are analyzed by separating the coating liquid into particle components and filtrate by ultrafiltration, and analyzing each of them by infrared spectroscopic analysis, gel permeation chromatography, fluorescent X-ray spectroscopic analysis, etc. And can be evaluated by analyzing the spectrum.

  The contents described in the above-mentioned sections “photocatalyst-coated body” and “photocatalyst coating liquid” can be arbitrarily combined.

Method for Producing Photocatalyst-Coated Body The photocatalyst-coated body of the present invention can be easily produced by applying the photocatalyst coating liquid on a substrate. As a method for coating the photocatalyst layer, generally used methods such as brush coating, roller, spray, roll coater, flow coater, dip coating, flow coating, and screen printing can be used. After applying the coating liquid to the substrate, it may be dried at room temperature, or may be heat-dried as necessary.

Base Material The base material used in the present invention may be various materials regardless of inorganic materials, organic materials, and multilayer materials, and the shape thereof is not limited. Preferred examples of the substrate from the viewpoint of materials include metals, ceramics, glass, plastics, rubber, stones, cement, concrete, fibers, fabrics, wood, paper, combinations thereof, laminates thereof, Examples thereof include those having at least one layer of coating on the surface. Preferred examples of base materials from the viewpoint of applications include building materials, building exteriors and interiors, window frames, window glass, structural members, exteriors and coatings of vehicles, exteriors of machinery and articles, dust covers and coatings, traffic signs, Various display devices, advertising towers, sound insulation walls for roads, sound insulation walls for railways, bridges, exterior and painting of guard rails, interior and painting of tunnels, insulators, solar battery covers, solar water heater heat collection covers, plastic houses, vehicle lighting Covers, outdoor lighting fixtures, tables, bathroom materials, kitchen panels, sinks, ranges, ventilation fans, air conditioning, filters, toilets, bathtubs, and films, sheets, seals and the like for attachment to the surface of the article.

In particular, the photocatalyst-coated body of the present invention is exposed to sunlight, and the photocatalyst is photoexcited by ultraviolet rays contained in the sunlight, causing photooxidation action such as gas decomposition and mold prevention, and deterioration of the substrate due to the ultraviolet rays. It is particularly preferable to use it in a usage form that may occur.
Such applications include building materials, building exteriors, window frames, window glass, structural members, exterior and painting of vehicles, exteriors of machinery and goods, traffic signs, advertising towers, signboards, sound insulation walls for roads, sound insulation walls for railways, bridges , Guard rail exteriors and paintings, tunnel interiors and paintings, insulators, solar cell covers, solar water heater heat collection covers, greenhouses, vehicular lighting lamp covers, outdoor lighting fixtures, road pavements and the like.
Particularly preferably, a substrate whose surface is enamel-coated or clear-coated is most preferable because the effect of the present invention can be fully enjoyed.

  The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

Example 1.
1.3 parts by mass of anatase-type titanium oxide particles (average crystallite size 10 nm), 8.7 parts by mass of silica particles (average particle size 50 nm) 5% surface-coated with trifunctional silane, 90 parts by mass of methylphenyl silicone emulsion A photocatalyst aqueous coating liquid having a solid content concentration of 25% by mass was prepared, dried on a transparent acrylic substrate at 150 ° C. for 5 minutes, and then irradiated with sunlight for 3 days under fine weather to obtain a photocatalyst-coated body.
When the photocatalyst layer of the obtained photocatalyst-coated body was observed in cross section, the film thickness was about 7 μm, and it was observed that anatase-type titanium oxide particles and silica particles were present at a high concentration on the surface.
Moreover, when the contact angle with water at the initial stage was measured, it was 8 °. When observed from the surface of the photocatalyst-coated body, the experimental table on which the coated body was placed was seen through.
About this photocatalyst coating body, the photocatalytic decomposition activity was confirmed by investigating NOx decomposition | disassembly performance. Here, the NOx decomposition function by the photocatalyst was performed by the test method of JIS R1701-1 “Testing method for air purification performance of photocatalytic material—Part 1: Nitrogen oxide removal performance”. As a result, ΔNOx exceeded 0.5 μmol, indicating a good result.
The photocatalytic hydrophilic performance was determined by the test method of JIS R1703-1 “Testing method for self-cleaning performance of photocatalytic material—Part 1: Measurement of water contact angle”. As a result, the water contact angle after 24 hours was less than 10 °.

Example 2
1.3 parts by mass of anatase-type titanium oxide particles (average crystallite diameter 10 nm), 8.7 parts by mass of silica particles (average particle diameter 50 nm) 5% surface-coated with trifunctional silane, 90 parts by mass of dimethyl silicone emulsion were blended. A photocatalytic aqueous coating solution having a solid concentration of 25% by mass was prepared, dried on a transparent acrylic substrate at 150 ° C. for 5 minutes, and then irradiated with sunlight for 3 days under fine weather to obtain a photocatalyst-coated body.
When the photocatalyst layer of the obtained photocatalyst-coated body was observed in cross section, the film thickness was about 7 μm, and it was observed that anatase-type titanium oxide particles and silica particles were present at a high concentration on the surface.
Moreover, when the contact angle with water at the initial stage was measured, it was 8 °. When observed from the surface of the photocatalyst-coated body, the experimental table on which the coated body was placed was seen through.
About this photocatalyst coating body, the photocatalytic decomposition activity was confirmed by investigating NOx decomposition | disassembly performance. Here, the NOx decomposition function by the photocatalyst was performed by the test method of JIS R1701-1 “Testing method for air purification performance of photocatalytic material—Part 1: Nitrogen oxide removal performance”. As a result, ΔNOx exceeded 0.5 μmol, indicating a good result.
The photocatalytic hydrophilic performance was determined by the test method of JIS R1703-1 “Testing method for self-cleaning performance of photocatalytic material—Part 1: Measurement of water contact angle”. As a result, the water contact angle after 24 hours was less than 10 °.

Claims (10)

A photocatalyst-coated body provided with a photocatalyst layer on a substrate surface,
The photocatalyst layer is obtained by applying a photocatalyst coating liquid and drying it,
The photocatalytic coating liquid comprises photocatalytic metal oxide particles, silica particles, and a curable silicone emulsion,
The silica particles are partially coated or modified with a silane having a hydrophobic group and / or a silicone having a hydrophobic group,
The hydrophobic group-containing silane and / or the hydrophobic group-containing silicone are coated with the photocatalyst coating liquid on the surface of the base material, dried, and then subjected to photoexcitation reaction of the photocatalytic metal oxide particles. A photocatalyst-coated body, wherein at least a part of the photocatalyst layer is substituted with a hydroxyl group and the surface of the photocatalyst layer becomes hydrophilic.   The photocatalyst-coated body according to claim 1, wherein the silica particles have a total amount of hydroxyl groups and alkoxy groups bonded to silicon atoms of less than 6 mmol / g.   3. The photocatalyst coating according to claim 1, wherein a cured product of the curable silicone emulsion contained in the photocatalyst coating solution is contained in the photocatalyst layer in an amount of 85% by mass or more. body.   The photocatalyst-coated body according to any one of claims 1 to 3, wherein the photocatalyst layer has a thickness of more than 2 µm and less than 20 µm.   The photocatalyst-coated body according to any one of claims 1 to 4, wherein an average particle size of the curable silicone emulsion is larger than an average particle size of the photocatalytic metal oxide particles and the silica particles. .   The photocatalyst-coated body according to any one of claims 1 to 5, wherein the photocatalyst layer is transparent. Photocatalytic metal oxide particles;
Silica particles;
A curable silicone emulsion;
With water,
The silica particles are partially coated or modified with a silane having a hydrophobic group and / or a silicone having a hydrophobic group,
The photocatalyst coating solution is used by a method of forming a photocatalyst layer on the surface of the substrate by drying after coating on the substrate,
The silane having a hydrophobic group and / or the silicone having a hydrophobic group in the photocatalyst coating liquid is applied to a substrate and then dried, and then at least a part of the hydrophobic group is obtained by a photoexcitation reaction of the photocatalytic metal oxide particles. Is replaced with a hydroxyl group, and the surface of the layer becomes hydrophilic.
A photocatalyst coating solution characterized by that.   The photocatalyst coating solution according to claim 7, wherein the silica particles have a total amount of hydroxyl groups and alkoxy groups bonded to silicon atoms of less than 6 mmol / g.   The cured product of the curable silicone emulsion contained in the photocatalyst coating solution is contained in an amount of 85% by mass or more based on the dried product of the photocatalyst coating solution. The photocatalyst coating liquid described in 1.   The photocatalyst coating liquid according to any one of claims 7 to 9, wherein an average particle size of the curable silicone emulsion is larger than an average particle size of the photocatalytic metal oxide particles and the silica particles. .