Photocatalyst-coated object and photocatalytic coating fluid therefor

The present invention is a photocatalyst coating body having a photocatalyst layer having high transparency, excellent weather resistance, harmful gas decomposability, and various coating properties, which is particularly suitable for use in exterior materials such as buildings, and a photocatalyst coating liquid for that purpose. Regarding.

Photocatalysts such as titanium oxide have been used in recent years in many applications such as building exterior materials. By using a photocatalyst, it is possible to decompose various harmful substances by using light energy, or to make the surface of a base material coated with a 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 (for example, Patent Document 1). JP-A-11-140432)). In this technique, the hydrophilicity is strengthened by containing a large amount of a surfactant of 10 to 25% by weight. Moreover, by setting the film thickness to 0.4 μm or less, white turbidity due to diffused reflection of light is prevented.

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

A technique for forming a photocatalytic coating film by transmitting 50% or more of light having a wavelength of 500 nm and blocking 80% or more of light at 320 nm using a photocatalytic paint is also known (for example, Patent Document 3 (Japanese Patent Laid-Open No. 2004)). -See (No. 359902). In this technique, an organosiloxane partial hydrolyzate is used as a binder for the photocatalytic paint, and it is said that the blending amount thereof is preferably 5 to 40% by mass of the entire paint composition.

By the way, it has been conventionally known that when the base material of the photocatalyst layer is composed of an organic material, the organic material is decomposed or deteriorated by the photocatalytic activity of the photocatalyst. In order to deal with this problem, a technique is known that protects the underlying carrier from deterioration due to photocatalytic action by providing an adhesive layer such as a silicon-modified resin between the photocatalytic layer and the carrier (for example, Patent Document 4). (See International Publication No. 97/00134 pamphlet).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 11-140432</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 11-169727</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2004-359902</text></patcit><patcit num="4"><text>International Publication No. 97/00134 Pamphlet</text></patcit></p>

The present inventors have recently constructed a photocatalyst layer having a specific composition containing photocatalyst particles and inorganic oxide particles in a specific mass ratio and containing no hydrolyzable silicone or containing as little as possible. , A photocatalytic coating body with excellent weather resistance, harmful gas decomposition properties, and various desired film properties (ultraviolet absorption, transparency, film strength, etc.) while suppressing erosion of the substrate (particularly organic substrate). We obtained the finding that it can be obtained.

Therefore, an object of the present invention is to achieve weather resistance, harmful gas decomposability, and various desired coating properties (ultraviolet absorption, transparency, film strength, etc.) while preventing erosion of the substrate (particularly an organic substrate). It is an object of the present invention to provide a photocatalyst coating body provided with an excellent photocatalyst layer and a photocatalyst coating liquid for the same.

That is, the photocatalyst coated body according to the present invention is a photocatalyst coated body provided with a base material and a photocatalyst layer provided on the base material. The photocatalyst layer Photocatalytic particles having an average particle size of 10 nm or more and 100 nm or less, 5 parts by mass or more and 15 parts by mass or less, Inorganic oxide particles of more than 75 parts by mass and 95 parts by mass or less, With a dried product of hydrolyzable silicone of 0 parts by mass or more and less than 10 parts by mass in terms of silica Is included so that the total amount of the photocatalytic particles, the inorganic oxide particles, and the hydrolyzable silicone in terms of silica is 100 parts by mass, and further contains 0 parts by mass or more and 10 parts by mass or less of the surfactant. It will be.

Further, the photocatalyst coating liquid according to the present invention is a photocatalyst coating liquid used for producing the above-mentioned photocatalyst coating body. With solvent Photocatalytic particles having an average particle size of 10 nm or more and 100 nm or less, 5 parts by mass or more and 15 parts by mass or less, Inorganic oxide particles of more than 75 parts by mass and 95 parts by mass or less, With hydrolyzable silicone of 0 parts by mass or more and less than 10 parts by mass in terms of silica Is included so that the total amount of the photocatalytic particles, the inorganic oxide particles, and the hydrolyzable silicone in terms of silica is 100 parts by mass, and further contains 0 parts by mass or more and 10 parts by mass or less of the surfactant. It will be.

<u style="single">Photocatalyst coating</u> 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 photocatalyst particles having a linear transmittance of 95% or more and 5 parts by mass or more and 15 parts by mass or less and an average particle size of 10 nm or more and 100 nm or less, and more than 75 parts by mass and 95 parts by mass. It contains less than a part of inorganic oxide particles and, as an optional component, a dried product of hydrolyzable silicone of 0 parts by mass or more and less than 10 parts by mass in terms of silica. Here, the total amount of the photocatalytic particles, the inorganic oxide particles, and the hydrolyzable silicone in terms of silica is 100 parts by mass.

That is, it is basically composed of photocatalytic particles having an average particle size of 10 nm or more and 100 nm or less, which is 5 parts by mass or more and 15 parts by mass or less, and inorganic oxide particles which are more than 75 parts by mass and 95 parts by mass or less according to the present invention. To. With this configuration, photocatalytic coating with excellent weather resistance, harmful gas decomposition properties, and various desired coating properties (ultraviolet absorption, transparency, film strength, etc.) while preventing erosion of the substrate (particularly organic substrate). It becomes possible to obtain a body. The reason why these excellent effects are realized at the same time is not clear, but it is thought that they are as follows. However, the following explanation is merely a hypothesis, and the present invention is not limited to any of the following hypotheses. 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, which is widely used as a binder for the photocatalyst layer, is used, the gaps between such particles are densely filled, which is considered to hinder the diffusion of gas. However, since the photocatalyst layer of the present invention does not contain hydrolyzable silicone, or even if it does, the total amount of photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone is less than 10 parts by mass with respect to 100 parts by mass. It is considered that a sufficient gap between the particles can be secured. Then, such a gap realizes a structure in which harmful gases such as NOx and SOx are easily diffused into the photocatalytic layer, and as a result, the harmful gas may be efficiently contacted with the photocatalytic particles and decomposed by the photocatalytic activity. Conceivable.

At the same time, the proportion of the photocatalyst particles is much lower than that of the inorganic oxide particles, which minimizes the direct contact of the photocatalyst particles with the substrate, thereby reducing the substrate (especially the organic substrate). It is thought that it will be difficult to erode. Further, it is considered that the amount of ultraviolet rays reaching the base material can be reduced by the absorption of ultraviolet rays by the photocatalyst itself, and the damage to the base material due to the ultraviolet rays can be reduced. As a result, the photocatalyst layer of the present invention can be directly applied to a base material whose surface is formed of an organic material without interposing an intermediate layer for protecting the base material. Therefore, since the formation of the intermediate layer is not required, the time and cost required for manufacturing the photocatalyst coated body can be reduced. Then, when various phenomena as described above occur at the same time, weather resistance, harmful gas decomposability, and various desired film characteristics (ultraviolet absorption, transparency) are prevented while preventing erosion of the base material (particularly the organic base material). It is considered that a photocatalyst coated body having excellent properties, film strength, etc.) will be realized.

Further, by ensuring the linear transmittance of the photocatalyst layer at a wavelength of 550 nm of 95% or more, 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.

<u style="single">Base material</u> The base material used in the present invention may be any material regardless of whether it is an inorganic material or an organic material as long as it is a material on which a photocatalyst layer can be formed, and its shape is not limited. Preferred examples of substrates from a material point of view are metals, ceramics, glass, plastics, rubber, stones, cement, concrete, fibers, fabrics, wood, paper, combinations thereof, laminates thereof, and their laminates. Those having at least one layer of coating on the surface can be mentioned. Preferred examples of the base material from the viewpoint of application are building materials, building exteriors, window frames, windowpanes, structural members, exteriors and coatings of vehicles, exteriors of machinery and articles, dustproof covers and coatings, traffic signs, and various displays. Equipment, advertising towers, sound insulation walls for roads, sound insulation walls for railways, bridges, exterior and painting of guard rails, interior and painting of tunnels, glass, solar cell covers, solar water heater heat collecting covers, greenhouses, vehicle lighting covers , Outdoor lighting fixtures, stands, and general exterior materials such as films, sheets, seals, etc. for being attached to the surface of the above-mentioned articles.

According to a preferred embodiment of the present invention, as the base material, a base material whose surface is at least formed of an organic material can be used, and the entire base material is made of an organic material or an inorganic material. It includes any of the base materials whose surface is coated with an organic material (for example, a decorative board). According to the photocatalyst layer of the present invention, even an organic material that is easily damaged by photocatalytic activity is not easily eroded. 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 because the formation of the intermediate layer becomes unnecessary.

<u style="single">Photocatalyst layer and photocatalyst coating liquid for it</u> The photocatalyst layer of the present invention comprises photocatalyst particles having an average particle size of 10 nm or more and 100 nm or less, which is 5 parts by mass or more and 15 parts by mass or less, and inorganic oxide particles which are more than 75 parts by mass and 95 parts by mass or less in terms of silica. A dried product of hydrolyzable silicone of 0 parts by mass or more and less than 10 parts by mass is included so that the total amount of photocatalyst particles, inorganic oxide particles, and the silica equivalent amount of the hydrolyzable silicone is 100 parts by mass. .. The photocatalyst layer can be formed by applying a photocatalyst coating solution in which photocatalyst particles, inorganic oxide particles, and hydrolyzable silicone are dispersed in a solvent in the above mass ratio on a 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, and 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 base material are sufficiently attenuated, so that the weather resistance is improved. Further, since the photocatalyst particles having a lower content ratio than the inorganic oxide particles can be increased in the film thickness direction, the harmful gas decomposability is also improved. Furthermore, excellent properties can be obtained in terms of ultraviolet absorption, transparency, and film strength.

The photocatalytic particles used in the present invention are not particularly limited as long as they have photocatalytic activity, and all kinds of photocatalytic particles can be used. An example of photocatalytic particles is titanium oxide (TiO).₂), ZnO, SnO₂, SrTiO₃, WO₃, Bi₂O₃, Fe₂O₃Examples thereof include particles of metal oxide such as, preferably titanium oxide particles, and more preferably anatase-type titanium oxide particles. Titanium oxide is harmless, chemically stable, and available at low cost. Further, titanium oxide has a high bandgap energy, and therefore requires ultraviolet rays for photoexcitation and does not absorb visible light in the process of photoexcitation, so that color development due to complementary color components does not occur. 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 photocatalytic particles preferably have an average particle size of 10 nm or more and 100 nm or less, and more preferably 10 nm or more and 60 nm or less. The average particle size is calculated as a number average value obtained by measuring the length of any 100 particles in a field of view 200,000 times with a scanning electron microscope. A true sphere is the best shape for the particles, but it may be substantially circular or elliptical, and the length of the particles in that case is approximately calculated as ((major axis + minor axis) / 2). Within this range, weather resistance, harmful gas decomposability, and various desired film characteristics (ultraviolet absorption, transparency, film strength, etc.) are efficiently exhibited. Further, by using a commercially available photocatalyst in the form of a sol and setting the particle size to 30 nm or less, preferably 20 nm or less, a photocatalyst layer having particularly good transparency can be obtained.

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 mixing ratio of the photocatalyst particles in this way, it is possible to minimize the direct contact of the photocatalyst particles with the base material, prevent erosion of the base material (particularly organic material), and also have weather resistance. It is thought that it will improve. Nevertheless, the functions caused by the photocatalytic activity such as harmful gas decomposability and ultraviolet absorption can be fully exerted.

According to a preferred embodiment of the present invention, it 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 exhibit even higher photocatalytic activity. At least one metal and / or a metal compound composed of the metal can be added to the photocatalyst layer and the photocatalyst coating liquid. This addition can be carried out by either a method of adding the solution in which the photocatalyst and the metal or the metal compound coexist as it is, or a method of supporting the metal or the metal compound on the photocatalyst by utilizing the photocatalytic redox action. Can be done.

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 the photocatalytic particles, and all kinds of inorganic oxide particles can be used. Examples of such inorganic oxide particles are single oxide particles such as silica, alumina, zirconia, ceria, itria, boronia, magnesia, calcia, ferrite, atypical titania, hafnia; and barium titanate, cay. Examples thereof include particles of a composite oxide such as calcium acid acid, and more preferably silica particles. These inorganic oxide particles are preferably in the form of an aqueous colloid using water as a dispersion medium; or an organosol in which the particles are colloidally dispersed in a hydrophilic solvent such as ethyl alcohol, isopropyl alcohol, or ethylene glycol, and particularly preferably. Colloidal silica.

According to a preferred embodiment of the present invention, the inorganic oxide particles preferably have an average particle size of 10 nm or more and less than 40 nm, and more preferably 10 nm or more and 30 nm or less. The average particle size is calculated as a number average value obtained by measuring the length of any 100 particles in a field of view 200,000 times with a scanning electron microscope. A true sphere is the best shape for the particles, but it may be substantially circular or elliptical, and the length of the particles in that case is approximately calculated as ((major axis + minor axis) / 2). Within this range, weather resistance, harmful gas decomposability, and various desired film characteristics (ultraviolet absorption, transparency, film strength, etc.) 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 of the total amount of the photocatalyst particles, the inorganic oxide particles, and the hydrolyzable silicone in terms of silica. It is 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 photocatalytic layer of the present invention preferably does not substantially contain a dried product of hydrolyzable silicone, and more preferably does not contain it at all. Hydrolyzable silicone is a general term for organosiloxane having an alkoxy group and / or a partially hydrolyzed condensate thereof. However, it is permissible 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 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 hydrolyzable silicone in terms of silica. Is 5 parts by mass or less, most preferably 0 parts 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 methyl). It is commercially available in the form of base) (both manufactured by Corcote).

The photocatalytic 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 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. It is preferably 0 parts by mass or more and 8 parts by mass or less, and more preferably 0 or more and 6 parts by mass or less. One of the effects of the surfactant is leveling property to the base material, and the amount of the surfactant may be appropriately determined depending on the combination of the coating liquid and the base material, and the lower limit value at that time is 0.1 part by mass. Good. This surfactant is an effective component for improving the wettability of the photocatalyst coating liquid, but in the photocatalyst layer formed after coating, it is an unavoidable impurity that no longer contributes to the effect of the photocatalyst coating body of the present invention. Equivalent to. Therefore, depending on the wettability required for the photocatalytic coating liquid, it may be used within the above-mentioned content range, and if the wettability is not a problem, the surfactant may be substantially or not contained. The surfactant to be used can be appropriately selected in consideration of the dispersion stability of the photocatalyst and the inorganic oxide particles and the wettability when applied on the intermediate layer, but a nonionic surfactant is preferable. More preferably, ether-type nonionic surfactants, ester-type nonionic surfactants, polyalkylene glycol nonionic surfactants, fluorine-based nonionic surfactants, and silicon-based nonionic surfactants are used. Can be mentioned.

The photocatalytic coating liquid of the present invention can be obtained by dispersing photocatalytic particles, inorganic oxide particles, and optionally hydrolyzable silicone and a surfactant in the solvent in the above-mentioned specific blending ratio. As the solvent, any solvent capable of appropriately dispersing the above-mentioned components can be used, and water and / or an organic solvent may be used. 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. For the analysis of the components in the photocatalyst coating composition, the coating liquid is separated into particle components and filtrate by ultrafiltration, and each is analyzed by infrared spectroscopic analysis, gel permeation chromatography, fluorescent X-ray spectroscopic analysis, etc. It can be evaluated by analyzing the spectrum.

<u style="single">Production method</u> The photocatalyst-coated body of the present invention can be easily produced by applying the photocatalyst coating liquid of the present invention on a substrate. As a method for coating the photocatalyst layer, generally widely used methods such as brush coating, roller, spray, roll coater, flow coater, dip coating, flow coating, screen printing, electrodeposition, and vapor deposition can be used. After the coating liquid is applied to the substrate, it may be dried at room temperature, or may be heat-dried if necessary. As described above, according to the photocatalyst layer of the present invention, the photocatalytic coating material of the present invention is less likely to erode even an organic material that is easily damaged by photocatalytic activity, and therefore is called a photocatalyst layer without interposing an intermediate layer. It is possible to produce a photocatalytic coating body having excellent functions with one layer. As a result, the time and cost required for manufacturing the photocatalyst coated body can be reduced because the formation of the intermediate layer becomes unnecessary.

<p> The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples. The raw materials used to prepare the photocatalyst coating liquid in the following examples are as follows.<u style="single">Photocatalytic particles</u> Titania aqueous dispersion (average particle size: 30-60 nm, basic)<u style="single">Inorganic oxide particles</u> Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex 50, particle size: 20 to 30 nm, solid content content 48%) (used in Examples 1-26, 28, 31-34) Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex 40, particle size: 10 to 20 nm, solid content 40%) (used in Example 27) Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex S, particle size: 8 to 11 nm, solid content content 30%) (used in Example 29) Water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex XS, particle size: 4 to 6 nm, solid content 20%) (used in Example 30)<u style="single">Hydrolyzable silicone</u> Polycondensate of tetramethoxysilane (manufactured by Tama Chemical Industry Co., Ltd., trade name: M silicate 51)<u style="single">Surfactant</u>-Polyether-modified silicone-based surfactant (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: Silicone-modified polyether (KF-643))</p><p> Examples 1-5:<u style="single">Evaluation of weather resistance</u> A photocatalyst coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coating 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, an aqueous dispersion colloidal silica as an inorganic oxide, water as a solvent, and a polyether-modified silicone-based surfactant were mixed at the blending ratios shown in Table 1. A photocatalytic coating solution was obtained. This photocatalytic coating liquid does not contain hydrolyzable silicone. The total solid content concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating liquid was 5.5% by mass.</p><p> The obtained photocatalytic coating liquid was spray-coated on the colored organic coating body previously heated to 50 ° C., and dried at 120 ° C. for 5 minutes. In this way, 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 all of Examples 1 to 5.</p><p> The weather resistance test of the photocatalyst coated body having a size of 50 × 100 mm thus obtained was carried out as follows. The photocatalyst coated material was put into a sunshine weather meter (Suga Test Instruments Co., Ltd., S-300C) specified in JIS B7753. After 300 hours, the test piece was taken out, the color difference was measured before and after the accelerated test with the color difference meter ZE2000 manufactured by Nippon Denshoku, and the degree of discoloration was evaluated by comparing the Δb values.</p><p> The results obtained were as shown in Table 1. Here, G in the table indicates that the color hardly changed, and NG indicates that the Δb value changed to the positive 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, it is possible to have sufficient weather resistance even if the photocatalyst layer is coated on the organic substrate. Do you get it.</p><p><tables num="1"><img file="JP4933568B2_D0001.tif" /></tables></p><p> Example 6 ~ 9:<u style="single">Evaluation of harmful gas degradability</u> A photocatalyst coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coating 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 a photocatalyst, aqueous colloidal silica as an inorganic oxide, water as a solvent, a polyether-modified silicone-based surfactant, and tetramethoxysilane as a hydrolyzable silicone. The product was mixed with the compounding ratio shown in Table 2 to obtain a photocatalyst coating liquid. The photocatalytic coating liquids of Examples 6 and 7 do not contain hydrolyzable silicone. The total solid content concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating liquid was 5.5% by mass.</p><p> The obtained photocatalytic coating liquid was spray-coated on the colored organic coating body previously heated to 50 ° C., and dried at 120 ° C. for 5 minutes. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (μm) of the photocatalyst layer was measured by scanning electron microscope observation, it was about 1 μm in all cases.</p><p> The photocatalyst-coated body having a size of 50 × 100 mm thus obtained was subjected to a gas decomposition test as follows. 1mW / cm as pretreatment for photocatalyst coating²Irradiated with BLB light for 12 hours or more. One coated sample was set in the reaction vessel described in JIS R 1701. NO gas was mixed with air adjusted to 25 ° C and 50% RH to about 1000 ppb, and introduced into a light-shielded reaction vessel for 20 minutes. After that, 3mW / cm with the gas introduced²The BLB light adjusted to the above was irradiated for 20 minutes. After that, the reaction vessel was shielded from light again with the gas introduced. NOx removal amount is NO, NO before and after BLB light irradiation₂It was calculated from the concentration according to the following formula. NOx removal amount = [NO (after irradiation)-NO (during irradiation)]-[NO₂(At the time of irradiation)-NO₂(After irradiation)]</p><p> The results obtained were as shown in Table 2. Here, G in the table indicates that the NOx removal amount is 400 ppb or more, and NG indicates that the NOx removal amount is 10 ppb or less. As shown in Table 2, the photocatalyst layer was composed of photocatalyst particles and inorganic oxides, and substantially free of hydrolyzable silicone, so that good NOx decomposability was exhibited. On the other hand, it was found that NOx degradability was lost in those containing 10 parts by mass of hydrolyzable silicone.</p><p><tables num="2"><img file="JP4933568B2_D0002.tif" /></tables></p><p> Example 10 ~ 26:<u style="single">Measurement of linear transmittance and UV shielding rate</u> A photocatalyst coated body provided with a photocatalyst layer was produced as follows. First, a float plate glass having a wavelength of 550 nm and a transmittance of 94% was prepared as a base material. On the other hand, Table 3 shows a titania aqueous dispersion as a photocatalyst, an aqueous dispersion type colloidal silica as an inorganic oxide having an average particle size of 20 to 30 nm, water as a solvent, and a polyether-modified silicone-based surfactant. The mixture was mixed at a blending ratio to obtain a photocatalytic coating solution. Therefore, this photocatalytic coating solution does not contain hydrolyzable silicone. The total solid content concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating liquid was 5.5% by mass.</p><p> The obtained photocatalyst coating solution was spray-coated on the float glass plate previously heated to 50 ° C, and dried at 120 ° C for 5 minutes. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (μm) of the photocatalyst layer was measured by scanning electron microscope observation, it was the value shown in Table 3.</p><p> For the photocatalyst coating body with a size of 50 x 100 mm thus obtained, the linear (550 nm) transmittance and the ultraviolet (300 nm) shielding rate were measured as follows with an ultraviolet / visible / near-infrared spectrophotometer (UV manufactured by Shimadzu Corporation). -3150) was used.</p><p> The results obtained were as shown in Table 3. Here, the evaluation criteria for the linear transmittance and the ultraviolet shielding rate are as follows. &lt;Linear transmittance&gt; A: Straight line (550nm) transmittance is 97% or more B: Straight line (550 nm) transmittance is 95% or more and less than 97% C: Straight line (550 nm) transmittance is less than 95% &lt;UV shielding rate&gt; a: Ultraviolet (300nm) shielding rate is 80% or more b: Ultraviolet (300 nm) shielding rate is 30% or more and less than 80% c: Ultraviolet (300 nm) shielding rate is less than 30% As shown in Table 3, when the content of the photocatalyst in the photocatalyst layer is 5 parts by mass or more and 15 parts by mass or less, the film thickness is set to 0.5 μm or more and 3 μm or less to sufficiently block ultraviolet rays caused by deterioration of organic substances. Moreover, it was found that transparency can be ensured.</p><p><tables num="3"><img file="JP4933568B2_D0003.tif" /></tables></p><p> Example 27 ~ 30:<u style="single">Haze measurement</u> A photocatalyst coated body provided with a photocatalyst layer was produced as follows. First, a float plate glass having a wavelength of 550 nm and a transmittance of 94% was used as a base material. On the other hand, Table 4 shows a titania aqueous dispersion as a photocatalyst, an aqueous dispersion type colloidal silica as an inorganic oxide having various average particle sizes shown in Table 4, water as a solvent, and a polyether-modified silicone-based surfactant. The mixture was mixed at the compounding ratio shown in (1) to obtain a photocatalytic coating solution. Therefore, this photocatalytic coating solution does not contain hydrolyzable silicone. The total solid content concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating liquid was 5.5% by mass.</p><p> The obtained photocatalyst coating solution 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 photocatalytic coating body having a size of 50 × 100 mm thus obtained was measured using a haze meter (haze-gard plus manufactured by Gardner).</p><p> The results obtained were as shown in Table 4. As shown in Table 4, it was found that the haze value can be suppressed to less than 1% and transparency can be ensured by setting the particle size of the metal oxide in the photocatalyst layer to 10 to 30 nm.</p><p><tables num="4"><img file="JP4933568B2_D0004.tif" /></tables></p><p> Example 31 ~ 34:<u style="single">Evaluation of the effects of the addition of surfactants</u> A photocatalyst coated body provided with a photocatalyst layer was produced as follows. First, a colored organic coating 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, an aqueous dispersion colloidal silica as an inorganic oxide, water as a solvent, and a polyether-modified silicone-based surfactant were mixed at the blending ratios shown in Table 5. A photocatalytic coating solution was obtained. This photocatalytic coating liquid does not contain hydrolyzable silicone. The total solid content concentration of the photocatalyst and the inorganic oxide in the photocatalyst coating liquid was 5.5% by mass.</p><p> The obtained photocatalytic coating liquid was spray-coated on the colored organic coating body previously heated to 50 to 60 ° C, and dried at 120 ° C for 5 minutes. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (μm) of the photocatalyst layer was measured by scanning electron microscope observation, it was about 1 μm in all of Examples 31 to 34.</p><p> The photocatalyst-coated body having a size of 50 × 100 mm thus obtained was subjected to a gas decomposition test as follows. 1 mW / cm as pretreatment for photocatalyst²Irradiated with BLB light for 12 hours or more. One coated sample was set in the reaction vessel described in JIS R 1701. NO gas was mixed with air adjusted to 25 ° C and 50% RH to about 1000 ppb, and introduced into a light-shielded reaction vessel for 20 minutes. After that, 3mW / cm with the gas introduced²The BLB light adjusted to the above was irradiated for 20 minutes. After that, the reaction vessel was shielded from light again with the gas introduced. The amount of NOx removed was calculated from the NO and NO2 concentrations before and after BLB light irradiation according to the following formula. NOx removal amount = [NO (after irradiation)-NO (during irradiation)]-[NO₂(At the time of irradiation)-NO₂(After irradiation)]</p><p> The results obtained were as shown in Table 5. Here, the NOx removal rate in the table is shown relative to the removal amount of Example 32 as 100. As shown in Table 5, it was found that the removal rate was reduced by increasing the amount of the surfactant added.</p><p><tables num="5"><img file="JP4933568B2_D0005.tif" /></tables></p>