JP2009262153A - Photocatalyst-coated body and photocatalytic coating liquid therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst-coated body which is high in transparency, superior in weatherability, noxious gas decomposability, and various coating properties (such as ultraviolet absorptivity and film strength) while preventing corrosion of a substrate and a photocatalyst coating liquid therefor. <P>SOLUTION: The photocatalyst-coated body comprises the substrate and a photocatalyst layer provided on the substrate. The photocatalyst layer comprises 5 to 15 pts.mass of a photocatalyst particles whose average particle diameter is 10 to 100 nm; 75 to 95 pts.mass of inorganic oxide particles; and 0 to less than 10 pts.mass of a hydrolyzable silicone dried material expressed in terms of silica, provided that a total amount of the photocatalyst particles, the inorganic oxide particles and the hydrolyzable silicone expressed in terms of silica is 100 pts.mass and further contains a surfactant as an optional component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a photocatalyst-coated body provided with a photocatalyst layer having a high transparency, weather resistance, harmful gas decomposability, and various coating properties, and a photocatalyst coating liquid therefor, which are particularly suitable for the use of exterior materials such as buildings. About.

  In recent years, photocatalysts such as titanium oxide have been used in many applications such as exterior materials for buildings. By using photocatalyst, it is possible to decompose various harmful substances using light energy, or to make the surface of the substrate coated with photocatalyst hydrophilic and easily wash away dirt adhering to the surface with water. . The following are known as techniques for obtaining a photocatalyst-coated body coated with such a photocatalyst.

  A technique for imparting hydrophilicity to the surface of a synthetic resin or the like using an aqueous dispersion containing photocatalytic metal oxide particles, colloidal silica, and a surfactant is known (for example, Patent Document 1 ( (See JP-A-11-14432). In this technique, hydrophilicity is enhanced by containing a surfactant in a large amount of 10 to 25% by weight. Moreover, the cloudiness by the irregular reflection of light is prevented by making a film thickness into 0.4 micrometer or less.

  A technique for obtaining a photocatalyst by forming a coating film containing silica sol as a binder component and photocatalytic titanium dioxide on a substrate is also known (see, for example, Patent Document 2 (Japanese Patent Laid-Open No. 11-169727)). In this technique, the amount of silica sol added is 20 to 200 parts by weight with respect to titanium dioxide on the basis of SiO2, and the content ratio of titanium dioxide is high. In addition, the particle size of silica sol is as small as 0.1 to 10 nm.

  There is also known a technique for forming a photocatalyst coating film that transmits 50% or more of light having a wavelength of 500 nm and blocks 80% or more of light having a wavelength of 320 nm using a photocatalyst coating (for example, Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-2004)). No. -359902)). In this technique, an organosiloxane partial hydrolyzate is used as a binder of a photocatalyst coating material, and the blending amount is preferably 5 to 40% by mass of the entire coating composition.

  By the way, when the base material of a photocatalyst layer is comprised with an organic material, the problem that an organic material is decomposed | disassembled or deteriorated by the photocatalytic activity of a photocatalyst is known conventionally. In order to cope with this problem, a technique for protecting an underlying carrier from deterioration due to photocatalysis by providing an adhesive layer such as a silicon-modified resin between the photocatalyst layer and the carrier is known (for example, Patent Document 4). (See WO 97/00134 pamphlet).

Japanese Patent Application Laid-Open No. 11-14432 JP 11-169727 A JP 2004-359902 A WO97 / 00134 pamphlet

  The inventors of the present invention have recently constituted a photocatalyst layer with a specific composition containing photocatalyst particles and inorganic oxide particles at a specific mass ratio and containing no hydrolyzable silicone or keeping the amount as small as possible. A photocatalyst-coated body excellent in weather resistance, harmful gas decomposability, and various desired film properties (ultraviolet absorption, transparency, film strength, etc.) while suppressing erosion to the substrate (especially organic substrate) The knowledge that it was obtained was obtained.

  Accordingly, the object of the present invention is to provide weather resistance, harmful gas decomposability, and various desired film properties (ultraviolet absorption, transparency, film strength, etc.) while preventing erosion of the substrate (especially organic substrate). An object of the present invention is to provide a photocatalyst-coated body having an excellent photocatalyst layer and a photocatalyst coating liquid therefor.

That is, the photocatalyst-coated body according to the present invention is a photocatalyst-coated body including a base material and a photocatalyst layer provided on the base material,
The photocatalytic layer is
5 to 15 parts by mass of photocatalyst particles having an average particle diameter of 10 to 100 nm,
More than 75 parts by weight and less than 95 parts by weight of inorganic oxide particles;
A hydrolyzable silicone dry matter having a weight of 0 to less than 10 parts by weight in terms of silica, and the total amount of silica equivalents of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone is 100 parts by weight. And a surfactant is further contained in an amount of 0 to 10 parts by mass.

Moreover, the photocatalyst coating liquid according to the present invention is a photocatalyst coating liquid used for producing the photocatalyst-coated body,
A solvent,
5 to 15 parts by mass of photocatalyst particles having an average particle diameter of 10 to 100 nm,
More than 75 parts by weight and less than 95 parts by weight of inorganic oxide particles;
From 0 parts by mass to less than 10 parts by mass of hydrolyzable silicone in terms of silica, the total amount of silica equivalents of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone is 100 parts by mass. And a surfactant is further contained in an amount of 0 to 10 parts by mass.

Photocatalyst-coated body The photocatalyst-coated body according to the present invention comprises a base material and a photocatalyst layer provided on the base material. The photocatalyst layer has a linear transmittance of 95% or more for light having a wavelength of 550 nm, a photocatalyst particle having an average particle size of 10 nm to 100 nm of 5 parts by mass to 15 parts by mass, and more than 75 parts by mass to 95 parts by mass. Part or less of inorganic oxide particles and, as an optional component, 0 part by mass or more and less than 10 parts by mass of a hydrolyzable silicone dry matter in terms of silica. Here, the total amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone in terms of silica is 100 parts by mass.

  That is, it is basically composed of 5 parts by mass or more and 15 parts by mass or less of photocatalyst particles having an average particle diameter of 10 nm or more and 100 nm or less, and inorganic oxide particles of more than 75 parts by mass and 95 parts by mass or less. The With this configuration, photocatalyst coating with excellent weather resistance, harmful gas decomposability, and various desired coating properties (ultraviolet absorption, transparency, film strength, etc.) while preventing erosion of substrates (especially organic substrates) The body can be obtained. The reason why these excellent effects are realized at the same time is not clear, but is thought to be as follows. However, the following description is merely a hypothesis, and the present invention is not limited by the following hypothesis. First, since the photocatalyst layer is basically composed of two types of particles, photocatalyst particles and inorganic oxide particles, there are abundant gaps between the particles. When a large amount of hydrolyzable silicone widely used as a binder for the photocatalyst layer is used, it is considered that the gap between the particles is densely filled, and thus gas diffusion is hindered. However, the photocatalyst layer of the present invention does not contain hydrolyzable silicone or even if it contains less than 10 parts by mass with respect to 100 parts by mass of the total amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone, It is considered that a sufficient gap between particles can be secured. Such a gap realizes a structure in which harmful gases such as NOx and SOx are likely to diffuse into the photocatalyst layer, and as a result, the harmful gas may be efficiently contacted with the photocatalyst particles and decomposed by the photocatalytic activity. Conceivable.

  At the same time, the proportion of photocatalyst particles is considerably less than that of inorganic oxide particles, so that direct contact of the photocatalyst particles with the substrate can be minimized, thereby reducing the substrate (especially organic substrate). It is thought that it becomes difficult to erode. Further, it is considered that the amount of ultraviolet rays reaching the substrate can be reduced by the ultraviolet absorption by the photocatalyst itself, and damage to the substrate due to ultraviolet rays can be reduced. As a result, the photocatalyst layer of the present invention can be directly applied to a substrate having at least a surface formed of an organic material without interposing an intermediate layer for protecting the substrate. Therefore, the time and cost required for manufacturing the photocatalyst-coated body can be reduced by the amount that the intermediate layer is not required. The various phenomena described above occur simultaneously, preventing erosion of the base material (especially organic base material), weather resistance, harmful gas decomposability, and various desired film properties (ultraviolet absorption, transparent It is considered that a photocatalyst-coated body excellent in properties, film strength, etc. is realized.

  In addition, by ensuring 95% or more of the linear transmittance of the photocatalyst layer at a wavelength of 550 nm, it is possible to express without impairing the color and design of the base. Moreover, even if it is coated on highly transparent glass or plastic, the transparency is not impaired.

Base Material The base material used in the present invention may be various materials regardless of inorganic materials or organic materials as long as it can form a photocatalyst layer thereon, and the shape 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, window frames, window glass, structural members, exteriors and coatings of vehicles, exteriors of machinery and articles, dust covers and coatings, traffic signs, and various displays Equipment, 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 General exterior materials such as outdoor lighting fixtures, stands, and films, sheets, seals and the like for attaching to the article surface.

  According to a preferred embodiment of the present invention, a substrate having at least a surface formed of an organic material can be used as the substrate, and the entire substrate is formed of an organic material or an inorganic material. Any of those in which the surface of the substrate is coated with an organic material (for example, a decorative board) is included. According to the photocatalyst layer of the present invention, it is difficult to erode even to an organic material that is easily damaged by the photocatalytic activity, and therefore, a photocatalyst coating having an excellent function in one layer called a photocatalyst layer without interposing an intermediate layer The body can be manufactured. As a result, the time and cost required for manufacturing the photocatalyst-coated body can be reduced by the amount that the intermediate layer is not required.

Photocatalyst layer and photocatalyst coating liquid therefor The photocatalyst layer of the present invention comprises 5 to 15 parts by mass of photocatalyst particles having an average particle diameter of 10 to 100 nm and inorganic of more than 75 to 95 parts The total amount of oxide particles and 0 to 10 parts by mass of hydrolyzable silicone dry matter in terms of silica is 100 masses in terms of the amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone in terms of silica. To be part. The photocatalyst layer can be formed by applying a photocatalyst coating liquid in which the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone are dispersed in the solvent in the above-described mass ratio on the substrate. .

  According to a preferred embodiment of the present invention, the photocatalyst layer preferably has a film thickness of 0.5 μm or more and 3.0 μm or less, more preferably 1.0 μm or more and 2.0 μm or less. Within such a range, the ultraviolet rays that reach the interface between the photocatalyst layer and the substrate are sufficiently attenuated, thereby improving the weather resistance. Moreover, since the photocatalyst particles having a lower content ratio than the inorganic oxide particles can be increased in the film thickness direction, harmful gas decomposability is also improved. Furthermore, excellent characteristics can be obtained in terms of ultraviolet absorption, transparency, and film strength.

The photocatalyst particles used in the present invention are not particularly limited as long as they have photocatalytic activity, and all kinds of photocatalyst particles can be used. Examples of the photocatalyst particles include metal oxide particles such as titanium oxide (TiO ₂ ), ZnO, SnO ₂ , SrTiO ₃ , WO ₃ , Bi ₂ O ₃ , Fe ₂ O ₃ , and preferably titanium oxide. Particles, more preferably anatase type titanium oxide particles. Titanium oxide is harmless, chemically stable, and available at low cost. Titanium oxide has a high band gap energy, and therefore requires ultraviolet light for photoexcitation and does not absorb visible light in the process of photoexcitation, so that no color formation due to a complementary color component occurs. Titanium oxide is available in various forms such as powder, sol, and solution, but any form can be used as long as it exhibits photocatalytic activity. According to a preferred embodiment of the present invention, the photocatalyst particles preferably have an average particle size of 10 nm to 100 nm, more preferably 10 nm to 60 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, harmful gas decomposability, and various desired film properties (such as ultraviolet absorption, transparency, and film strength) are efficiently exhibited. In addition, a photocatalyst layer having particularly good transparency can be obtained by using a commercially available photocatalyst in a sol form and setting the particle diameter to 30 nm or less, preferably 20 nm or less.

  The content of the photocatalyst particles in the photocatalyst layer and the coating liquid of the present invention is preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the total amount of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone. Is 5 parts by mass or more and 10 parts by mass or less. By reducing the blending ratio of the photocatalyst particles in this way, the direct contact of the photocatalyst particles with the base material can be reduced as much as possible to prevent erosion of the base material (especially organic material) and the weather resistance is also improved. It is thought to improve. Nevertheless, functions due to photocatalytic activity such as decomposability of harmful gas and ultraviolet absorption can be sufficiently exhibited.

  According to a preferred embodiment of the present invention, the material is selected from the group consisting of titania and vanadium, iron, cobalt, nickel, palladium, zinc, ruthenium, rhodium, copper, silver, platinum and gold in order to develop higher photocatalytic ability. At least one metal and / or a metal compound comprising the metal can be added to the photocatalyst layer and the photocatalyst coating solution. This addition is performed by any of the method of adding a solution in which the photocatalyst and the metal or metal compound coexist as it is, and the method of supporting the metal or metal compound on the photocatalyst using the photocatalytic oxidation-reduction action. Can do.

  The inorganic oxide particles used in the present invention are not particularly limited as long as they are inorganic oxide particles capable of forming a layer together with photocatalyst particles, and any kind of inorganic oxide particles can be used. Examples of such inorganic oxide particles include single oxide particles such as silica, alumina, zirconia, ceria, yttria, boronia, magnesia, calcia, ferrite, amorphous titania, hafnia; and barium titanate, silica The particle | grains of complex oxides, such as calcium acid, are mentioned, 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 a preferred aspect of the present invention, the inorganic oxide particles preferably have an average particle size of 10 nm or more and less than 40 nm, more preferably 10 nm or more and 30 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 film properties (such as ultraviolet absorption, transparency, and film strength) are efficiently exhibited. In particular, a photocatalyst layer that is transparent and has good adhesion can be obtained.

  The content of the inorganic oxide particles in the photocatalyst layer and the coating liquid of the present invention exceeds 75 parts by mass with respect to 100 parts by mass as the total amount of silica of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone. 95 parts by mass or less, preferably more than 80 parts by mass and 95 parts by mass or less, more preferably 85 parts by mass or more and 95 parts by mass or less, and further preferably 90 parts by mass or more and 95 parts by mass or less.

  The photocatalyst layer of the present invention preferably contains substantially no dried hydrolyzable silicone, and more preferably does not contain at all. The hydrolyzable silicone is a general term for an organosiloxane having an alkoxy group and / or a partially hydrolyzed condensate thereof. However, it is allowed to contain hydrolyzable silicone as an optional component as long as the harmful gas decomposability of the present invention can be ensured. Therefore, the content of the hydrolyzable silicone is 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 hydrolyzable silicone in terms of silica. Is 5 parts by mass or less, and most preferably 0 part by mass. As the hydrolyzable silicone, a tetrafunctional silicone compound is often used. For example, ethyl silicate 40 (oligomer, R is an ethyl group), ethyl silicate 48 (oligomer, R is an ethyl group), methyl silicate 51 (oligomer, R is a methyl group) Group) (both manufactured by Colcoat Co.).

  The photocatalyst coating liquid may contain a surfactant as an optional component. The surfactant used in the present invention may be contained in the photocatalyst layer in an amount of 0 to less than 10 parts by mass with respect to 100 parts by mass of the total amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone, Preferably they are 0 mass part or more and 8 mass parts or less, More preferably, they are 0 or more and 6 mass parts or less. One of the effects of the surfactant is leveling to the substrate, and the amount of the surfactant may be appropriately determined depending on the combination of the coating liquid and the substrate, and the lower limit in that case is 0.1 part by mass. May be. This surfactant is an effective component for improving the wettability of the photocatalyst coating solution, but in the photocatalyst layer formed after coating, it is an inevitable impurity that no longer contributes to the effect of the photocatalyst-coated body of the present invention. Equivalent to. Therefore, it may be used within the above-mentioned content range depending on the wettability required for the photocatalyst coating liquid, and if the wettability is not a problem, the surfactant may be contained substantially or not at all. The surfactant to be used can be appropriately selected in consideration of the dispersion stability of the photocatalyst and inorganic oxide particles, and wettability when applied on the intermediate layer, but a nonionic surfactant is preferable, More preferably, an ether type nonionic surfactant, an ester type nonionic surfactant, a polyalkylene glycol nonionic surfactant, a fluorine-based nonionic surfactant, or a silicon-based nonionic surfactant is used. Can be mentioned.

  The photocatalyst coating liquid of the present invention can be obtained by dispersing photocatalyst particles, inorganic oxide particles, and optionally hydrolyzable silicone and a surfactant in the above-mentioned specific mixing ratio in a solvent. As the solvent, any solvent that can appropriately disperse the above-described constituent components can be used, and water and / or an organic solvent may be used. Moreover, the solid content concentration of the photocatalyst coating liquid of the present invention 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 spectroscopy, gel permeation chromatography, fluorescent X-ray spectroscopy, etc. It can be evaluated by analyzing the spectrum.

Manufacturing method The photocatalyst coating body of this invention can be easily manufactured by apply | coating the photocatalyst coating liquid of this invention on a base material. 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, screen printing, electrodeposition, vapor deposition and the like 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. As described above, according to the photocatalyst layer of the present invention, the photocatalyst-coated body of the present invention is not easily eroded even by an organic material that is easily damaged by photocatalytic activity. A photocatalyst-coated body having an excellent function in one layer can be produced. As a result, the time and cost required for manufacturing the photocatalyst-coated body can be reduced by the amount that the intermediate layer is not required.

The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.
In the following examples, the raw materials used for preparation of the photocatalyst coating liquid are as follows.
Photocatalyst particles / titania water dispersion (average particle size: 30-60 nm, basic)
Inorganic oxide particles / water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, trade name: Snowtex 50, particle size: 20-30 nm, solid content 48%) (Examples 1-26, Example 28, Example 31- 34)
-Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, trade name: Snowtex 40, particle size: 10-20 nm, solid content 40%) (used in Example 27)
-Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, trade name: Snowtex S, particle size: 8-11 nm, solid content 30%) (used in Example 29)
Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, trade name: Snowtex XS, particle size: 4-6 nm, solid content 20%) (used in Example 30)
Hydrolyzable silicone / tetramethoxysilane polycondensate (manufactured by Tama Chemical Co., Ltd., trade name: M silicate 51)
Surfactant / polyether-modified silicone surfactant (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: silicone-modified polyether (KF-643))

Examples 1 to 5: Evaluation of weather resistance A photocatalyst-coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coated body was prepared as a base material. This colored organic coated body is obtained by applying general-purpose acrylic silicone to which carbon black powder is added on a float plate glass and sufficiently drying and curing it. On the other hand, a titania aqueous dispersion as a photocatalyst, a water-dispersed colloidal silica as an inorganic oxide, water as a solvent, and a polyether-modified silicone surfactant are mixed at a blending ratio shown in Table 1, A photocatalytic coating solution was obtained. In addition, this photocatalyst coating liquid does not contain hydrolysable silicone. 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-coated on the colored organic coating body previously heated to 50 ° C. and dried at 120 ° C. for 5 minutes. Thus, a photocatalyst layer was formed to obtain a photocatalyst-coated body. When the film thickness of the photocatalyst layer was measured by observation with a scanning electron microscope, it was about 0.5 μm in any of Examples 1 to 5.

  About the photocatalyst coating body of a magnitude | size of 50x100 mm obtained in this way, the weather resistance test was done as follows. The photocatalyst-coated body was put into a sunshine weatherometer (S-300C, manufactured by Suga Test Instruments) defined in JIS B7753. After 300 hours, the test piece was taken out, the color difference was measured before and after the acceleration test with a color difference meter ZE2000 manufactured by Nippon Denshoku, and the degree of color change was evaluated by comparing the Δb values.

  The obtained results were as shown in Table 1. Here, G in the table indicates that the color has hardly changed, and NG indicates that the Δb value has shifted to the plus side (yellowing side). As shown in Table 1, by setting the content of the photocatalyst in the photocatalyst layer to 5 parts by mass or more and 15 parts by mass or less, the photocatalyst layer has sufficient weather resistance even if the photocatalyst layer is coated on the organic substrate. I understood.

Examples 6 to 9: Evaluation of harmful gas decomposability A photocatalyst-coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coated body was prepared as a base material. This colored organic coated body is obtained by applying general-purpose acrylic silicone to which carbon black powder is added on a float plate glass and sufficiently drying and curing it. On the other hand, polycondensation of titania aqueous dispersion as photocatalyst, water-dispersed colloidal silica as inorganic oxide, water as solvent, polyether-modified silicone surfactant, and tetramethoxysilane as hydrolyzable silicone Were mixed at a blending ratio shown in Table 2 to obtain a photocatalyst coating solution. In addition, the photocatalyst coating liquid of Example 6 and Example 7 does not contain hydrolysable silicone. 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-coated on the colored organic coating body previously heated to 50 ° C. and dried at 120 ° C. for 5 minutes. Thus, a photocatalyst layer was formed to obtain a photocatalyst-coated body. When the film thickness (μm) of the photocatalyst layer was measured by observation with a scanning electron microscope, it was about 1 μm in any of the examples.

The photocatalyst-coated body having a size of 50 × 100 mm thus obtained was subjected to a gas decomposability test as follows. As a pretreatment, the photocatalyst-coated body was irradiated with 1 mW / cm ² of BLB light for 12 hours or more. One coated body sample was set in the reaction vessel described in JIS R1701. NO gas was mixed with air adjusted to 25 ° C. and 50% RH so as to be about 1000 ppb, and introduced into a light-shielded reaction vessel for 20 minutes. Thereafter, BLB light adjusted to 3 mW / cm ² was irradiated for 20 minutes while the gas was introduced. Thereafter, the reaction vessel was shielded from light again with the gas introduced. The NOx removal amount was calculated according to the following formula from the NO and NO ₂ concentrations before and after the BLB light irradiation.
NOx removal amount = [NO (after irradiation) −NO (at irradiation)] − [NO ₂ (at irradiation) −NO ₂ (after irradiation)]

  The obtained results were as shown in Table 2. Here, G in the table represents a NOx removal amount of 400 ppb or more, and NG represents a NOx removal amount of 10 ppb or less. As shown in Table 2, when the photocatalyst layer was composed of photocatalyst particles and an inorganic oxide and substantially free of hydrolyzable silicone, good NOx decomposability was exhibited. On the other hand, those containing 10 parts by mass of hydrolyzable silicone were found to lose NOx decomposability.

Examples 10 to 26: Measurement of linear transmittance and ultraviolet shielding rate A photocatalyst-coated body provided with a photocatalyst layer was produced as follows. First, a float plate glass having a transmittance of 94% at a wavelength of 550 nm was prepared as a substrate. On the other hand, Table 3 shows titania water dispersion as a photocatalyst, water-dispersed colloidal silica as an inorganic oxide having an average particle diameter of 20 to 30 nm, water as a solvent, and a polyether-modified silicone surfactant. The photocatalyst coating liquid was obtained by mixing at a blending ratio. Therefore, this photocatalyst coating liquid does not contain hydrolyzable silicone. 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-coated on the float plate glass plate heated to 50 ° C. in advance, and dried at 120 ° C. for 5 minutes. Thus, a photocatalyst layer was formed to obtain a photocatalyst-coated body. When the film thickness (μm) of the photocatalyst layer was measured by observation with a scanning electron microscope, the values shown in Table 3 were obtained.

  With respect to the photocatalyst-coated body having a size of 50 × 100 mm obtained as described above, the measurement of the linear (550 nm) transmittance and the ultraviolet ray (300 nm) shielding rate was carried out by using an ultraviolet / visible / near infrared spectrophotometer (UV manufactured by Shimadzu Corporation). -3150).

The obtained results were as shown in Table 3. Here, the evaluation criteria of the linear transmittance and the ultraviolet shielding rate were as follows.
<Linear transmittance>
A: Linear (550 nm) transmittance is 97% or more B: Linear (550 nm) transmittance is 95% or more and less than 97% C: Linear (550 nm) transmittance is less than 95% <UV shielding factor>
a: Ultraviolet (300 nm) shielding rate of 80% or more b: Ultraviolet (300 nm) shielding rate of 30% or more and less than 80% c: Ultraviolet (300 nm) shielding rate of less than 30% As shown in Table 3, in the photocatalyst layer When the content of the photocatalyst is 5 parts by mass or more and 15 parts by mass or less, it was found that by setting the film thickness to 0.5 μm or more and 3 μm or less, it is possible to sufficiently shield the ultraviolet rays caused by the deterioration of organic substances and ensure transparency. .

Examples 27 to 30: Measurement of haze A photocatalyst-coated body provided with a photocatalyst layer was produced as follows. First, a float plate glass having a transmittance of 94% at a wavelength of 550 nm was used as a substrate. On the other hand, a titania aqueous dispersion as a photocatalyst, water-dispersed colloidal silica as an inorganic oxide having various average particle diameters shown in Table 4, water as a solvent, and a polyether-modified silicone surfactant are listed in Table 4. To obtain a photocatalyst coating liquid. Therefore, this photocatalyst coating liquid does not contain hydrolyzable silicone. 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 spin-coated on the above-mentioned substrate at 1000 rpm for 10 seconds and dried at 120 ° C. for 5 minutes to obtain a photocatalyst layer. The haze of the photocatalyst-coated body having a size of 50 × 100 mm obtained in this manner was measured using a haze meter (haze-gard plus from Gardner).

  The obtained results were as shown in Table 4. As shown in Table 4, it was found that by setting the particle size of the metal oxide in the photocatalyst layer to 10 to 30 nm, the haze value can be suppressed to less than 1% and the transparency can be secured.

Examples 31 to 34: Evaluation of influence by addition of surfactant A photocatalyst-coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coated body was prepared as a base material. This colored organic coated body is obtained by applying general-purpose acrylic silicone to which carbon black powder is added on a float plate glass and sufficiently drying and curing it. On the other hand, a titania aqueous dispersion as a photocatalyst, a water-dispersed colloidal silica as an inorganic oxide, water as a solvent, and a polyether-modified silicone surfactant are mixed at a blending ratio shown in Table 5, A photocatalytic coating solution was obtained. In addition, this photocatalyst coating liquid does not contain hydrolysable silicone. 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-coated on the colored organic coating body heated to 50 to 60 ° C. in advance, and dried at 120 ° C. for 5 minutes. Thus, a photocatalyst layer was formed to obtain a photocatalyst-coated body. When the film thickness (μm) of the photocatalyst layer was measured by observation with a scanning electron microscope, it was about 1 μm in any of Examples 31 to 34.

The photocatalyst-coated body having a size of 50 × 100 mm thus obtained was subjected to a gas decomposability test as follows. The photochromic catalyst body was irradiated with 1 mW / cm ² of BLB light as a pretreatment for 12 hours or more. One coated body sample was set in the reaction vessel described in JIS R1701. NO gas was mixed with air adjusted to 25 ° C. and 50% RH so as to be about 1000 ppb, and introduced into a light-shielded reaction vessel for 20 minutes. Thereafter, BLB light adjusted to 3 mW / cm ² was irradiated for 20 minutes while the gas was introduced. Thereafter, the reaction vessel was shielded from light again with the gas introduced. The NOx removal amount was calculated according to the following formula from the NO and NO2 concentrations before and after the BLB light irradiation.
NOx removal amount = [NO (after irradiation) −NO (at irradiation)] − [NO ₂ (at irradiation) −NO ₂ (after irradiation)]

  The results obtained were as shown in Table 5. Here, the NOx removal rate in the table is relatively shown with the removal amount of Example 32 as 100. As shown in Table 5, it was found that the removal rate was lowered by increasing the amount of the surfactant added.

Claims (1)

A method for producing a photocatalyst-coated body, comprising a base material and a photocatalyst layer provided on the base material,
A step of applying a photocatalyst coating liquid on a substrate;
The photocatalyst coating liquid is
A solvent,
5 to 15 parts by mass of photocatalyst particles having an average particle diameter of 10 to 100 nm,
More than 75 parts by weight and less than 95 parts by weight of inorganic oxide particles;
From 0 parts by mass to less than 10 parts by mass of hydrolyzable silicone in terms of silica, the total amount of silica equivalents of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone is 100 parts by mass. A method for producing a photocatalyst-coated body comprising: