JP5707389B2 - Photocatalyst paint - Google Patents

Description

Related applications

  This application claims the priority of Japanese Patent Application No. 2010-070198 filed on Mar. 25, 2010, and the specifications of these applications are incorporated herein by reference. The

  The present invention relates to a photocatalyst-coated body provided with a photocatalyst layer excellent in weather resistance, photocatalytic decomposability, light resistance, and various film performances, which is particularly suitable for applications such as exterior materials such as buildings and interior materials.

  In recent years, photocatalysts such as titanium oxide have been used in many applications such as exterior materials for buildings. Utilizing the activity excited by the photocatalyst's light energy, it is possible to decompose various harmful substances, or to make the substrate surface coated with the photocatalyst hydrophilic and easily wash away dirt adhering to the surface with water. It becomes.

When obtaining such a photocatalyst-coated body, an intermediate layer is provided between the base material serving as the base and the photocatalyst for the purpose of adhesion and / or suppression of deterioration of the base material surface due to the photocatalyst. As a technique for obtaining a photocatalyst-coated body coated with such a photocatalyst, a technique is known in which an intermediate layer such as a silicone-modified resin is provided between a base substrate and a photocatalyst. (For example, refer to Patent Document 1 (International Publication No. 97/00134 pamphlet)).

  A technique using beads as a filler in the intermediate layer is also known. (Refer to patent document 2 (Unexamined-Japanese-Patent No. 2009-136811)).

WO97 / 00134 pamphlet JP 2009-136811 A

  In order to increase the photocatalytic activity, the amount of the photocatalyst contained in the photocatalyst layer has been conventionally increased. However, in that case, there is a concern that the base material may be deteriorated by the photocatalyst. There was a limit.

  The present inventors can improve the photocatalytic activity by adding specific beads to the intermediate layer provided so as to be in contact with the lower side of the photocatalyst layer. As a result, the amount of photocatalyst in the photocatalyst layer is reduced. And the knowledge that deterioration of a base material can be prevented effectively was acquired. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide a photocatalyst-coated body that is excellent in the photocatalytic decomposition function while reducing the amount of photocatalyst contained in the photocatalyst layer.

That is, the photocatalyst-coated body according to the present invention includes a base material, a photocatalyst layer including photocatalyst particles, and an intermediate layer provided between the base material and the photocatalyst layer so as to be in contact with the lower side of the photocatalyst layer. A photocatalyst-coated body comprising at least
The intermediate layer comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, and a silicone-modified resin, and the beads include the intermediate layer and the photocatalyst layer. A convex portion due to the shape is formed on the interface.

The present invention also relates to a coating composition for forming the photocatalyst-coated body. The coating composition comprises a substrate, a photocatalyst layer containing photocatalyst particles, and the substrate and the photocatalyst layer. And a coating composition for forming the intermediate layer of the photocatalyst-coated body comprising at least an intermediate layer provided so as to be in contact with the lower side of the photocatalyst layer,
It comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, a silicone-modified resin, and a solvent, and the apparent density of the beads is smaller than that of the silicone-modified resin and the solvent. It is characterized by having been made.

  The present invention also relates to a method for producing the above-mentioned photocatalyst-coated body, which comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads on the surface of the substrate, and a silicone-modified resin. And a step of applying a coating solution comprising at least a solvent and then drying to form an intermediate layer, and applying a photocatalyst coating solution comprising photocatalyst particles to the intermediate layer to form a photocatalyst layer. And a process.

  According to the photocatalyst-coated body of the present invention, it is possible to provide a photocatalyst-coated body that has an excellent photocatalytic decomposition function while reducing the amount of photocatalyst contained in the photocatalyst layer.

Photocatalyst-coated body The photocatalyst-coated body according to the present invention is an intermediate provided between a base material, a photocatalyst layer containing photocatalyst particles, and the base material and the photocatalyst layer so as to be in contact with the lower side of the photocatalyst layer. A photocatalyst-coated body comprising at least a layer, wherein the intermediate layer includes at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, and a silicone-modified resin. The bead is formed by forming a convex portion due to its shape at the interface between the intermediate layer and the photocatalyst layer.

  The reason why the photocatalyst-coated body according to the present invention makes it possible to provide a photocatalyst-coated body that reduces the amount of photocatalyst contained in the photocatalyst layer and is excellent in the photocatalytic decomposition function is not clear, but is considered as follows. The convex part resulting from the shape of a bead is formed in the interface of the intermediate | middle layer of a photocatalyst coating body by this invention, and a photocatalyst layer, As a result, moderate unevenness | corrugation is formed in the photocatalyst layer on an intermediate | middle layer. It is thought that this moderate unevenness increases the surface area of the photocatalyst layer surface, and as a result, the photocatalytic decomposition function is improved. However, this is only a hypothesis, and the present invention is not limited by this.

  In the present invention, the bead forms a convex portion due to its shape at the interface between the intermediate layer and the photocatalytic layer. Here, the convex portion resulting from the shape of the beads refers to a portion formed due to a relatively protruding presence of at least a part of the beads at the interface between the intermediate layer and the photocatalytic layer. In the present invention, the beads may or may not be exposed from the intermediate layer. In addition, irregularities caused by other than the interface beads between the intermediate layer and the photocatalyst layer may exist. In one embodiment of the present invention, when the beads are made of resin, the beads are not exposed at the interface, the modified silicone covers the beads, and the modified silicone is in contact with the photocatalyst layer from the viewpoint of weather resistance. preferable. In the present invention, it may be a convex portion that substantially conforms to the shape of the bead, or a convex portion that slightly reflects the shape of the bead.

  In addition, the photocatalyst-coated body according to the present invention is advantageous in that the effect of enhancing the adhesion between the intermediate layer and the photocatalyst layer can be expected depending on the unevenness at the interface between the intermediate layer and the photocatalyst layer.

Intermediate Layer The intermediate layer of the present invention comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, and at least a silicone-modified resin.

  In the present invention, the beads are at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, preferably resin beads. Examples of the resin constituting the beads include acrylic resin, epoxy resin, polyamide resin, polyurethane resin, unsaturated polyester resin, vinyl ester resin, phenol resin, silicone resin, acrylic silicone resin, fluorine resin, ketone resin, polyethylene resin, Polypropylene resin, super short oil alkyd resin, short oil alkyd resin, medium oil alkyd resin, long oil alkyd resin, super long oil alkyd resin, melamine resin, amino alkyd cocondensation resin, urea resin, vinyl chloride resin, vinyl acetate resin, polyvinyl Examples include alcohol and polyvinyl butyral.

  According to a preferred embodiment of the present invention, the particle size of the beads is larger than the film thickness of the photocatalyst layer of the photocatalyst-coated body. According to another preferred embodiment of the present invention, the particle size of the beads is smaller than the film thickness of the intermediate layer of the photocatalyst-coated body. According to a preferred embodiment of the present invention, the thickness of the intermediate layer is preferably 1 μm or more and 100 μm or less, a more preferred lower limit is 3 μm, a further preferred lower limit is 10 μm, and a preferred upper limit is 50 μm. Therefore, the particle size of the beads can be appropriately determined in consideration of the above, but more specifically, it is preferably in the range of 0.3 to 30 μm, more preferably 1 to 30 μm, and most preferably 3 to 30 μm.

  The added amount of beads is preferably 1 to 50%, more preferably 3 to 30%, and most preferably 5 to 20% with respect to the solid content weight of the intermediate layer. By being in the above range, an improvement in the photocatalytic decomposition function can be obtained, and an adverse effect on the substrate can be effectively prevented.

    In the present invention, by setting the film thickness of the intermediate layer, the diameter of the beads, and the amount added thereof within the above range, a convex portion resulting from the shape can be efficiently formed at the interface between the intermediate layer and the photocatalyst layer. Conceivable.

  Furthermore, according to one preferred embodiment of the present invention, in the coating composition for forming the intermediate layer described later, the apparent density of the beads is higher than the components of the composition other than the beads, particularly at least the silicone-modified resin and the solvent. Is also considered to be small. Thereby, when forming the intermediate layer, the beads float upward in the composition, and the beads can be collected near the interface with the photocatalyst layer of the intermediate layer, thereby efficiently forming the convex portion due to the shape thereof. be able to. In addition to adjusting the thickness of the intermediate layer, the diameter of the beads, and the amount of the beads added, by using beads with a small apparent density, the convex portion due to the shape of the interface between the intermediate layer and the photocatalyst layer can be more efficiently used. It is thought that can be formed.

  The intermediate layer of the photocatalyst-coated body according to the present invention comprises at least the above beads and a silicone-modified resin. The silicone-modified resin basically functions as a matrix for the intermediate layer. Specific examples thereof include silicone-modified acrylic resins, silicone-modified epoxy resins, silicone-modified urethane resins, and silicone-modified polyesters containing polysiloxane in the resin. Available.

  According to one preferred embodiment of the present invention, the intermediate layer of the photocatalyst-coated body according to the present invention is formed by using, as a coating composition for forming the intermediate layer, an aqueous dispersion of a silicone-modified resin containing the above beads as a substrate. After application, preferably after application, it can be cured and formed. Examples of such an aqueous dispersion include a resin-based colloidal dispersion containing a siloxane of about 50 to 200 nm, a curable silicone-modified resin emulsion, and the like.

  The resin-based colloidal dispersion is a water dispersion composed of a composite resin in which a polymer segment such as acrylic or urethane having a silyl group is combined with a branched polysiloxane segment having a hydroxyl group bonded to a silicon atom. Examples include the body.

  According to another preferred embodiment of the present invention, the silicone-modified resin matrix of the intermediate layer may be formed by applying a curable silicone-modified resin emulsion to a substrate and then curing it. 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 that causes the curing reaction, an organic cross-linked portion by emulsion polymerization is present. 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.

  Further, 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 a hydrocarbon group such as an alkyl group, a phenyl group, and a cycloalkyl group, and an organic group in which a part of the hydrogen is substituted with a modifying group. Here, examples of the modifying group include an amino group, a carboxyl group, a mercapto group, an acrylic group, and an epoxy group.

  As the surfactant used as an emulsifier for the above-mentioned emulsion, conventionally known nonionic, cationic and anionic surfactants and reactive emulsifiers containing functional groups capable of radical polymerization can be used. Specific examples of usable nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene carboxylic acid ester, sorbitan ester, polyoxyethylene sorbitan ester, and alkyltrimethylammonium chloride. , Cationic surfactants such as alkylbenzylammonium chloride, anionic surfactants such as alkyl or alkylallylsulfate, alkyl or alkylallylsulfonate, dialkylsulfosuccinate, amino acid type, betaine type, etc. Ionic type surfactants, radicals containing hydrophilic groups such as sulfonates, polyoxyethylene chains, quaternary ammonium salts in the molecules described in JP-A-8-27347 If Possible (meth) acrylate, styrene, 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.

  According to one preferable aspect of the present invention, the siloxane (Si—O) content in the silicone-modified resin constituting the silicone-modified resin matrix is 0.4 mass% or more to the solid content of the silicone-modified resin. It is made to be less than mass%, more preferably 12 mass% or more and less than 33 mass%. Thereby, weather resistance to ultraviolet rays in the intermediate layer and erosion by the photocatalyst can be sufficiently suppressed, and generation of cracks can be efficiently suppressed. Here, the silicon atom content in the silicone-modified resin can be measured by chemical analysis using an X-ray photoelectron spectrometer (XPS).

  According to a preferred embodiment of the present invention, the intermediate layer can further comprise an ultraviolet absorber. Thereby, the weather resistance of the intermediate layer can be improved. 0.001-10 mass% is preferable, and, as for the addition amount of the ultraviolet absorber with respect to an intermediate | middle layer, More preferably, it is 0.01-5 mass%. Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, and triazine-based ultraviolet absorbers. Among the triazine-based ultraviolet absorbers, hydroxyphenyltriazine is excellent in absorption characteristics at a wavelength of 380 nm or less, and chemical. It is preferable because it is stable.

  The hydroxyphenyl triazine compound is a derivative of hydroxyphenyl triazine and / or hydroxyphenyl triazine having a basic skeleton represented by the following general formula, and a commercially available hydroxyphenyl triazine-based ultraviolet absorber can be suitably used.

  According to a preferred embodiment of the present invention, the intermediate layer further contains a hindered amine-based and / or hindered phenol-based light stabilizer. Due to the synergistic effect with the ultraviolet absorber, the weather resistance and light resistance of the photocatalyst-coated body according to the present invention can be expected to be improved. In particular, when a hydroxyphenyltriazine compound is used as an ultraviolet absorber, a hindered amine is preferably selected as a light stabilizer. The hydroxyphenyl triazine compound provides an advantage that the absorption performance of ultraviolet rays having a short wavelength of less than 380 nm is stabilized. The content of the light stabilizer with respect to the intermediate layer is 0.001 to 10% by mass, preferably 0.01 to 5% by mass.

  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 (product name: TINUVIN-292, manufactured by Ciba Japan Co., Ltd.), bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, TINUVIN-123 (product name, Ciba Japan Co., Ltd.), TINUVIN-111FDL (product name, manufactured by Ciba Japan Co., Ltd.), TINUVIN 292 (product name, manufactured by Ciba Japan Co., Ltd.), 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 Such as ru-4-iminopiperidyl methacrylate, 4-cyano-2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-cyano-1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, etc. Examples thereof include polymerizable hindered amine ultraviolet absorbers and their (co) polymers. Specific examples of the hindered phenol light stabilizer include bis (3,5-tert-butyl) -4-hydroxytoluene, TINUVIN-144 (product name, manufactured by Ciba Japan Co., Ltd.), and the like. it can.

  The intermediate layer of the photocatalyst-coated body according to the present invention can contain extender pigments, colored pigments, algaeproofing agents, viscosity modifiers and the like as optional components.

  Examples of extender pigments include titanium oxide whisker, calcium carbonate whisker, aluminum borate whisker, potassium titanate whisker, mica, and talc.

  Examples of the color pigment include titanium oxide white, zinc oxide white iron oxide, carbon black, spinel green, bengara, cobalt aluminate, ultramarine blue and the like, phthalocyanine series, benzimidazolone series, isoindolinone series, azo And organic color pigments such as those based on anthraquinone, quinophthalone, anthrapyridinine, quinacridone, toluidine, pyrathrone and perylene.

  As the anti-algae, organic anti-fungal agents having good compatibility with the resin component of the intermediate layer can be suitably used. For example, organic nitrogen sulfur compounds, pyrithion compounds, organic iodine compounds, triazine compounds, isothiazolines Compounds, imidazole compounds, pyridine compounds, nitrile compounds, thiocarbamate compounds, thiazole compounds, disulfide compounds, and the like.

  Examples of the viscosity modifier include organic bentonite, ultrafine silica, surface-treated calcium carbonate, amide wax, hydrogenated castor oil wax, benzylidene sorbitol, various metal soaps, polyethylene oxide, and polymerized vegetable oil. , Sulfate ester anionic surfactant, polyether ester type surfactant, polycarboxylic acid amine salt, magnesium aluminum silicate, xanthan gum, guar gum, polyacrylate soda, acrylic acid / acrylate copolymer (Alkali thickening system), polyvinyl alcohol system, polyethylene oxide system, urethane-modified polyether system and the like.

  The intermediate layer can be produced by applying, preferably applying, the above-described composition comprising at least beads and a silicone-modified resin on a substrate. As a method for applying the intermediate layer, generally used methods such as brush coating, roller, spray, roll coater, flow coater, dip coating, flow coating, screen printing and the like can be used. After application of the composition to the substrate, the intermediate layer is formed by drying at room temperature or, if necessary, drying by heating. By drying, it is possible to maintain the state in which the beads floating upward in the composition are collected near the surface of the intermediate layer serving as the interface with the photocatalyst layer, and it is possible to efficiently form convex portions due to the shape thereof It becomes possible.

  As a solvent of the coating composition for forming the intermediate layer, any solvent can be used as long as it can disperse the above-mentioned constituents appropriately, and water and / or an organic solvent may be used. Moreover, although the solid content concentration of this composition is not specifically limited, about 10-60 mass% is preferable from an ease of application | coating, More preferably, it is about 15-50 mass%. In addition, the component analysis of the composition for intermediate | middle layer formation can be performed by infrared spectroscopy about a resin component.

  In addition to the above, the coating composition for forming the intermediate layer may contain paint additives such as pigment dispersants, antifoaming agents and antioxidants, and other components usually contained in paints. Further, a matting agent such as silica fine particles may be included.

Photocatalyst layer The photocatalyst layer of the present invention is a layer containing photocatalyst particles provided on an intermediate layer.

  Examples of the photocatalyst particles include metal oxide particles such as anatase type titanium oxide, rutile type titanium oxide, brookite type titanium oxide, tin oxide, zinc oxide, strontium titanate, tungsten oxide, and cerium oxide.

  According to a preferred embodiment of the present invention, the photocatalyst 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, photocatalytic decomposability, and various desired coating properties (transparency, coating strength, etc.) are efficiently exhibited.

  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. And / or a metal compound comprising the metal can be added to a photocatalyst coating solution applied on the intermediate layer to form a photocatalyst layer or a photocatalyst layer. 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.

  According to a preferred aspect of the present invention, the content of the photocatalyst particles contained in the photocatalyst layer is more than 1% by mass and less than 20% by mass, more preferably more than 1% by mass and less than 5% by mass. To do. When the content of the photocatalyst particles is within this range, an effect that the decomposition function of the photocatalyst is effectively exhibited and the base material and the intermediate layer are hardly deteriorated can be efficiently obtained.

  In a preferred embodiment of the present invention, the photocatalyst layer has air permeability. Thereby, the contact opportunity of a photocatalyst particle and a to-be-decomposed thing increases, and the outstanding photocatalyst decomposition function is exhibited.

The photocatalyst layer of the photocatalyst-coated body according to the present invention preferably contains substantially no hydrolyzable silicone polycondensate in order to ensure air permeability, and more preferably does not contain at all. Here, the hydrolyzable silicone is a general term for an organosiloxane having an alkoxy group and / or a partially hydrolyzed condensate thereof. The content of the hydrolyzable silicone polycondensate is 0 to 10 parts by mass with respect to 100 parts by mass of the total amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone polycondensate in terms of silica. Is preferably 5 parts by mass or less, and most preferably 0 part by mass. As the hydrolyzable silicone, a silicone compound having 2 to 4 functional silane as a monomer unit is often used, and for example, ethyl silicate, methyl silicate, alkyl group-containing silicone, phenyl group-containing silicone and the like can be suitably used.

  In order to ensure air permeability, the photocatalyst layer of the photocatalyst-coated body according to the present invention preferably does not substantially contain a polycondensate of a hydrolyzate of an organometallic compound, and more preferably does not contain at all. Here, the organometallic compound is a metal alkoxide containing a metal element such as titanium, zirconium, or aluminum, a metal organic complex, or the like. The content of the polycondensation product of the hydrolyzate of the organic metal is 0 parts by mass or more and 10 parts by mass with respect to 100 parts by mass in total of the photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone in terms of metal oxide Is preferably 5 parts by mass or less, and most preferably 0 part by mass.

  The photocatalyst layer of the present invention comprises at least one selected from the group consisting of a hydrolyzable silicone polycondensate and an organometallic compound hydrolyzate as an optional component. The content of the optional component is preferably 0 parts by mass or more and less than 10 parts by mass with respect to 100 parts by mass of the total amount of the photocatalyst particles, the inorganic oxide particles, and the oxide conversion amount of these optional components, Preferably it is 5 mass parts or less, Most preferably, it is 0 mass part.

  According to a preferred aspect of the present invention, the photocatalyst layer can contain inorganic oxide particles in addition to the photocatalyst particles. This inorganic oxide particle functions as a binder component, gives sufficient air permeability to the photocatalyst layer, increases the chance of contact between the photocatalyst particle and the substance to be decomposed, and provides an advantage that an excellent photocatalytic decomposition function is exhibited. .

  The inorganic oxide particles are not particularly limited as long as they are inorganic oxide particles capable of forming a layer together with photocatalyst particles. Examples of such inorganic oxide particles include silica, alumina, zirconia, ceria, yttria, Examples include single oxide particles such as tin oxide, iron oxide, manganese oxide, nickel oxide, cobalt oxide, and hafnia; and composite oxide particles such as barium titanate, calcium silicate, aluminum borate, and potassium titanate. More preferably, it is a silica particle. These inorganic oxide particles are preferably in the form of an aqueous colloid using water as a dispersion medium; or an organosol dispersed in a hydrophilic solvent such as ethyl alcohol, isopropyl alcohol, or ethylene glycol, and particularly preferably. Colloidal silica.

  According to one preferable aspect of the present invention, the inorganic oxide particles have an average particle size of more than 5 nm and not more than 20 nm, preferably not less than 10 nm and not more than 20 nm. 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, photocatalytic decomposability, and various desired coating properties (transparency, coating strength, etc.) can be efficiently exhibited, and in particular, a photocatalyst layer that is transparent and has good adhesion can only be obtained. Instead, a film that is strong against sliding wear can be obtained.

  According to one preferred embodiment of the present invention, the photocatalyst layer comprises more than 1 part by weight and less than 20 parts by weight of photocatalyst particles, more than 70 parts by weight and less than 99 parts by weight of inorganic oxide particles, and as optional components, At least one selected from the group consisting of a polycondensation product of degradable silicone and a polycondensation product of a hydrolyzate of an organometallic compound, wherein the photocatalyst particles, the inorganic oxide particles, and 0 parts by mass or more and less than 10 parts by mass The total amount of the optional component in terms of oxide is included to be 100 parts by mass. More preferably, the photocatalyst layer has a photocatalyst particle of more than 1 part by mass and less than 5 parts by mass, an inorganic oxide particle of more than 85 parts by mass and less than 99 parts by mass, and condensation polymerization of hydrolyzable silicone as an optional component. And at least one selected from the group consisting of polycondensates of hydrolysates of organometallic compounds, wherein the photocatalyst particles, the inorganic oxide particles, and the oxides of the optional components The total amount of the conversion amount is configured to be 100 parts by mass. By using such a photocatalyst layer, the opportunity of contact between the photocatalyst particles and the substance to be decomposed is increased, and an excellent photocatalyst decomposition function is effectively exhibited. It is possible to improve to such an extent that it can withstand use. Furthermore, the deterioration of the base material and the intermediate layer due to the photocatalyst can be suppressed.

  According to one preferable aspect of the present invention, the photocatalyst layer of the photocatalyst-coated body according to the present invention is substantially transparent.

  According to a preferred embodiment of the present invention, the film thickness of the photocatalyst layer is preferably from 0.1 μm to 5.0 μm, more preferably from 0.5 μm to 3.0 μm, and most preferably from 1.0 μm to 2. 0 μm or less. By being in such a range, the photocatalyst particles having a lower content ratio than the inorganic oxide particles can be increased in the film thickness direction, and the photocatalytic decomposability can be improved. Furthermore, excellent characteristics can be obtained in transparency.

  The photocatalyst-coated body according to the present invention can be easily produced by applying, preferably applying, a photocatalyst coating liquid containing photocatalyst particles and a solvent on a substrate having an intermediate layer formed by the above-described method. As a method for applying 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 if necessary.

  The photocatalyst added to the photocatalyst coating liquid may be added in the form of a sol. As the solvent of the sol, a solvent that can appropriately disperse the above constituent components can be used, and water and / or an organic solvent. And water is particularly preferred.

  Moreover, as a solvent of said photocatalyst coating liquid, the solvent which can disperse | distribute the said structural component appropriately can be used, and may be water and / or an organic solvent. Moreover, the solid content concentration of the photocatalyst coating liquid is not particularly limited, but it is preferably 1 to 10% by mass because it is easy to apply. The components in the photocatalyst coating composition are analyzed by separating the coating solution into particle components and filtrate by ultrafiltration, and analyzing each by infrared spectroscopic analysis, gel permeation chromatography, fluorescent X-ray spectroscopic analysis, etc. It can be evaluated by analyzing the spectrum.

  The photocatalyst coating liquid may contain a surfactant as an optional component. The surfactant may be contained in an amount of 0 to 10 parts by mass with respect to the photocatalyst coating liquid, preferably 0 to 8 parts by mass, more preferably 0 to 6 parts by mass. is there. One of the effects of adding a surfactant is leveling to the substrate, and the lower limit for obtaining the effect is about 0.1 parts by mass. Further, the surfactant is an effective component for improving the wettability of the photocatalyst coating liquid, but in the photocatalyst layer formed after coating, the inevitable impurities that no longer contribute to the effect of the photocatalyst-coated body of the present invention. It corresponds to. Therefore, the surfactant may be used within the above content range depending on the wettability required for the photocatalyst coating solution, but if the wettability is not a problem, the surfactant is substantially or not included. It is not necessary. The type of the surfactant can be appropriately selected in consideration of the dispersion stability of the photocatalyst and the inorganic oxide particles and the wettability when coated on the intermediate layer, but a nonionic surfactant is preferred, more Preferably, ether type nonionic surfactants, ester type nonionic surfactants, polyalkylene glycol nonionic surfactants, fluorine-based nonionic surfactants, silicon-based nonionic surfactants, and the like It is done.

Base Material The base material of the photocatalyst-coated body of the present invention may be any material, regardless of inorganic material or organic material, as long as the intermediate layer can be formed thereon, 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, guard rail exteriors and paintings, tunnel interiors and paintings, insulators, solar cell 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.

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

<Preparation of painted body sample>
Examples and comparative examples were produced as follows.
Example 1
As the substrate, a white enamel coated substrate was prepared.
The intermediate layer was formed as follows. That is, 100 parts by weight of a silicone-modified acrylic resin emulsion (solid content concentration: 40%) having a siloxane content of 30% by mass with respect to the solid content of the silicone-modified resin, a color pigment slurry (rutile titanium oxide, solid content concentration: 65%) is mixed with 43 parts by weight, acrylic resin beads (average particle size: 18 μm) is 16 parts by weight, ion-exchanged water is 55 parts by weight, viscosity modifier is mixed with 4 parts by weight, and water is used as a solvent to coat the intermediate layer. A liquid was obtained. This coating solution was roller-coated on the substrate and dried at room temperature (23 ° C.) for 24 hours to form an intermediate layer having a thickness of 40 μm.

  The photocatalyst layer was formed as follows. That is, an anatase-type titanium oxide aqueous dispersion (average particle size: about 50 nm, dispersant: diethylamine) and water-dispersed colloidal silica (average particle size: about 11 nm, basic) are mixed to obtain a photocatalyst coating liquid. It was. The total solid concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating solution was 5.5% by mass. The obtained photocatalyst coating liquid was spray-applied on the above-mentioned intermediate coating material heated in advance and dried at room temperature (23 ° C.) for 24 hours. The obtained photocatalyst layer contained 10 parts by mass of titanium oxide and 90 parts by mass of silica. The film thickness of the photocatalyst layer was 0.5 μm.

Examples 2-10
The acrylic resin beads shall have the average particle diameter described in the table described later, and the thickness of the intermediate layer was changed to the film thickness described in the table below by adjusting the amount of the intermediate layer coating solution. A photocatalyst-coated body was obtained in the same manner as in Example 1. In the case of Examples 8 and 9, 8 parts by weight of hollow inorganic glass beads (average particle size: 30 or 16 μm) were added instead of acrylic resin beads. In the case of Example 10, acrylic resin beads were not added.

Evaluation of photocatalytic resolution

  About the obtained photocatalyst coating body, according to the test method of JISR1703-2 "Self-cleaning performance test method of photocatalyst material-Part 2: Wet decomposition performance", the methylene blue resolution was evaluated. The obtained degradation activity index was as shown in the following table.

Claims (10)

A photocatalyst-coated body comprising at least a base material, a photocatalyst layer comprising photocatalyst particles, and an intermediate layer provided between the base material and the photocatalyst layer and in contact with the photocatalyst layer. There,
The intermediate layer comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, and a silicone-modified resin, and the beads include the intermediate layer and the photocatalyst layer. It is formed by forming convex portions due to its shape at the interface ,
The photocatalyst-coated body , wherein the particle size of the beads is smaller than the film thickness of the intermediate layer, and the amount of the beads is 1% by mass or more and 50% by mass or less of the intermediate layer. .   The photocatalyst-coated body according to claim 1, wherein the particle diameter of the beads is larger than the film thickness of the photocatalyst layer. The photocatalyst coating body of Claim 1 or 2 whose particle size of the said bead is 0.3-30 micrometers. The photocatalyst coating body as described in any one of Claims 1-3 whose said photocatalyst layer is transparent. The photocatalyst coating body as described in any one of Claims 1-4 whose film thickness of the said intermediate | middle layer is 1 micrometer or more and 100 micrometers or less. The photocatalyst-coated body according to any one of claims 1 to 5 , wherein the beads are resin beads. A coating composition for forming the intermediate layer of the photocatalyst-coated body according to any one of claims 1 to 6 ,
It comprises at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, a silicone-modified resin, and a solvent, and the apparent density of the beads is smaller than that of the silicone-modified resin and the solvent. A coating composition, characterized in that it is made. The coating composition according to claim 7 , wherein the beads are resin beads. A coating liquid comprising at least one kind of beads selected from the group consisting of resin beads, hollow glass beads, and hollow ceramic beads, a silicone-modified resin and a solvent is applied to the substrate surface, and then dried. 7. The method according to claim 1 , comprising: a step of forming an intermediate layer; and a step of forming a photocatalyst layer by applying a photocatalyst coating liquid containing photocatalyst particles to the intermediate layer. A method for producing a photocatalyst-coated body according to claim 1. The method for producing a photocatalyst-coated body according to claim 9 , wherein the beads are resin beads.