Photocatalytic coating agent and method for producing a photocatalytic coating agent

Abstract

This improves the dispersibility of water-soluble titanium dioxide-based photocatalytic coating agents and enhances their adhesion to the coating surface. [Solution] The method for producing the photocatalytic coating agent according to this embodiment includes a step of mixing peroxo-modified anatasesol, peroxotitanic acid, and visible light sol, wherein each of the peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol is 0.1 to 2.0 wt%, and the difference in solid content concentration between them is 0.2 wt%.

Description

【Technical Field】 【0001】 This invention relates to a photocatalyst coating agent. 【Background Art】 【0002】 The photocatalyst coating agent uses titanium dioxide (TiO2) etc. as a catalyst. When irradiated with light, electrons with excited negative charges jump out, and holes are generated in titanium dioxide etc. The electrons jumping out from this catalyst combine with oxygen (O2) to generate "O2-" (superoxide anion). On the other hand, the electrons in "H2O" in the air react with this hole and move, and this "H2O" becomes "·OH" (hydroxyl radical). Both the "superoxide anion" and "hydroxyl radical" that appear due to the movement of electrons can decompose organic substances etc. by oxidative decomposition power. For example, it repeatedly decomposes and removes various dangerous substances such as the oil content, miscellaneous bacteria, mold bacteria, viruses, and harmful chemical gases in the air that cause approaching bad odors and dirt adhesion, and emits them as harmless substances into the air. 【0003】 Patent Document 1 discloses a method for producing a photocatalyst, which includes a first step of mixing titanium butoxide in an aqueous solution of an organic solvent, heating it to 150 - 220°C to hydrolyze titanium butoxide, and drying this to obtain an intermediate product, and a second step of firing the intermediate product at 150 - 300°C. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2014 - 128768 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 The photocatalyst described in Patent Document 1 is in the form of particulate matter or powder. In order to obtain a photocatalytic film using particulate matter or powder, the challenges lie in forming the powdered photocatalyst into a film and in how to make the photocatalytic powder into fine particles. 【0006】 In such photocatalytic coating agents, a film made of crystallized photocatalytic powder is formed on the wall or other surface of the object to be coated. However, this film has problems with adhesion and may peel off, potentially preventing the photocatalytic effect from being obtained on the coated object (substrate). There was also the problem of difficulty in dispersion. Furthermore, such photocatalytic coating agents require the use of a binder. 【0007】 This invention was made in view of the above-mentioned problems, and its purpose is to prevent a decrease in the dispersion stability of the photocatalytic coating agent. [Means for solving the problem] 【0008】 The photocatalytic coating agent of the embodiment comprises peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol, and furthermore, the solid content concentration of each of the peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol is 0.1 to 2.0 wt%, and the difference in their respective solid content concentrations is 0.2 wt%. In addition, the visible light sol in the above photocatalytic coating agent may also contain platinum-supported titanium oxide. In addition, the wt% of the peroxo-modified anatasesol, peroxotitanic acid, and visible light sol in the above photocatalytic coating agent may be substantially the same. The method for producing the photocatalytic coating agent of the embodiment comprises the steps of setting the solid content concentration of each of the peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol to within the range of 0.1 to 2.0 wt%, and mixing the peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol, with the difference in their respective solid content concentrations being 0.2 wt%. Furthermore, in the method for producing the photocatalytic coating agent according to the above embodiment, the wt% of the peroxo-modified anatase sol, the peroxotitanic acid aqueous solution, and the visible light sol may be substantially the same. [Effects of the Invention] 【0009】 According to the embodiment, it is possible to improve the dispersion stability of the mixture when mixing peroxo-modified anatase sol (hereinafter referred to as "PA"), peroxotitanic acid aqueous solution (hereinafter referred to as "PTA") and visible light sol (such as platinum-supported titanium oxide solution; hereinafter referred to as "PtTiO2" as an example) in the manufacturing process of a photocatalytic coating agent. [Brief explanation of the drawing] 【0010】 [Figure 1] A graph showing the results of antiviral and antibacterial performance evaluation tests of silver ions. [Figure 2] A diagram showing PA and PTA. [Figure 3] A table showing the 1st to 15th examples and comparative examples 1 to 5. [Modes for carrying out the invention] 【0011】 Embodiments of the invention are described below. These descriptions and embodiments are illustrative and do not limit the scope of the invention. 【0012】 In the following, "photocatalytic coating agent" refers to a coating agent containing a photocatalyst that exhibits antibacterial, deodorizing, and antifouling properties, and repeatedly purifies the environment, upon exposure to light. 【0013】 The inventors have focused on the fact that the dispersion stability of a photocatalyst (solution, powder) containing peroxotitanic acid-based (PA, etc.) photocatalysts that mainly react to ultraviolet light, titanium dioxide-based (copper-supported, platinum-supported, etc.) photocatalysts that mainly respond to visible light, and PTA may decrease depending on the solid content of each component when mixing them. When dispersion stability decreases, sufficient stirring may be required when applying the coating agent to an object by dropping, spraying, coating, etc. Alternatively, the dispersant and photocatalyst may clearly separate in the coating agent, making stirring insufficient. 【0014】 Furthermore, if the solid content concentration of the photocatalyst is too low, sufficient photocatalytic function cannot be ensured. 【0015】 Therefore, in mixing PA, which has excellent photocatalytic function, PTA, which has good binder function to the substrate, and a photocatalyst sol that reacts to visible light (e.g., titanium oxide supported by a metal (copper / platinum, etc.)), we realized that adjusting the solid content concentration of each solution is necessary to prevent a decrease in dispersion stability while maximizing the photocatalytic function. Furthermore, this effect is even more necessary if silver ions, which can be used in the dark, are to be included. 【0016】 <Photocatalyst> Examples of photocatalysts in this embodiment include compounds of metal elements with oxygen, nitrogen, sulfur, and fluorine. Furthermore, three types of photocatalysts are used: those with high binder function to the substrate, those with photocatalytic function that reacts to ultraviolet light, and those that react to visible light. 【0017】 Examples of these metallic elements include Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Ga, In, Tl, Ge, Sn, Pd, Bi, La, and Ce. Examples of compounds include oxides, nitrides, sulfides, oxynitrides, oxysulfides, nitrogen fluorides, oxyfluorides, and oxynitride compounds of one or more of these precious metallic elements. 【0018】 Examples of binders with high functionality for the substrate include, for example, peroxotitanic acid (PTA). The proportion of PTA in the mixing ratio of PA, PTA, and the visible light sol is about 10 to 40%. Since high film strength is often required outdoors, the mixing ratio of PTA is set relatively high. On the other hand, for porous substrates, the film strength can be suppressed, so the photocatalyst medium can be strengthened. Examples of porous substrates include, for example, plaster walls and mortar walls. 【0019】 Examples of photocatalysts with high photocatalytic functionality that react to ultraviolet light include PA. This PA is anatase-type titanium oxide sol with spear-shaped crystal particles having OH groups. The average dispersed particle diameter is about 2 to 100 nm. An example is shown in Figure 2. The proportion of PA in the mixing ratio of PA, PTA, and the visible light sol is about 50 to 80%. The peroxo-modified anatase sol is in a defective crystal state, that is, it retains water solubility while crystallizing. 【0020】 Examples of photocatalysts with high photocatalytic functionality that react to visible light (visible light sol) include platinum-supported titanium oxide (rutile-type titanium dioxide (PtTiO2) supported with platinum). In addition to Pt, other metal-supported titanium oxides such as Fe and Cu may also be used. The proportion of the visible light sol in the mixing ratio of PA, PTA, and the visible light sol is about 3 to 20%. Therefore, the mixing ratios of PA:PTA:PtTiO2 are, for example, (1) 5:3:2 (2) 5:4:1 (3) 6:3:1 (4) 6:2:2 (5) 6:3.7:0.3 (6) 7:2:1 (7) 7:1:2 (8) 7:2.7:0.3 (9) 8:1:1 (10) 8:1.7:0.3, etc., and their peripheral values. 【0021】 <Solvent> As the solvent, for example, an aqueous medium mainly composed of water or an inorganic solvent can be used. The solid dispersion concentration of the solvent and the photocatalyst medium will be described in detail later. 【0022】 <Silver ion> Silver ions (Ag+) have antibacterial and deodorizing effects without the need for light. The photocatalytic coating agent of this embodiment includes not only a photocatalyst that reacts to ultraviolet light but also a photocatalyst that reacts to visible light. Furthermore, by including these silver ions, the coating agent can exert its intended function even in places with low light levels or in the dark, thereby improving the functionality of the coating agent (see Figure 1). However, while silver ions have antibacterial and deodorizing functions, they may become harmful if the concentration is too high. In this regard, when water-soluble titanium dioxide is used as in this embodiment, the dispersibility of silver ions in the coating agent is good. Therefore, even if only a small amount of silver ions are added, the coating agent can exert antibacterial, deodorizing, and other functions. In other words, the advantageous functions of silver ions can be exerted without introducing any disadvantages of silver ions. When water-soluble titanium dioxide is used as in this embodiment, a stable coating film is formed by ionic bonding, and the antibacterial, deodorizing, and other effects of silver are sustained. [Examples] 【0023】 The embodiments of the invention will be described in detail below with reference to examples. However, the above embodiments are not limited to these examples, and include other embodiments that can be conceived from the above embodiments. The following description is based on the results prepared and tested under the conditions shown in Figure 2. 【0024】 <First Example> The photocatalytic coating agent according to the first embodiment will be described. 0.1 wt% PA (peroxo-modified anatase sol) with pure water as the solvent, 0.1 wt% PTA with pure water as the solvent, and 0.1 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) as the photocatalyst, along with silver ion water with pure water as the solvent, are mixed. The mixing ratio of PA:PTA:PtTiO2 is 5:4:1. A mixer, vibration, or ultrasound can be used as appropriate for mixing and stirring. 【0025】 To test the photocatalytic coating agent prepared as described above, test specimens were prepared as follows: A predetermined amount of the coating agent was sprayed onto a 5cm x 5cm white tile using an air spray gun. The test specimens were then irradiated with a predetermined amount of ultraviolet light (black light) and left to air dry in a room at 20°C for 120 minutes. 【0026】 Two tests were performed on the test specimens prepared as described above. In the first test, a predetermined concentration and amount of red ink was sprayed onto the test specimen, and the time it took for the red ink to decompose under ultraviolet light irradiation was measured. In the second test, a predetermined concentration and amount of red ink was sprayed onto the test specimen, and the time it took for the red ink to decompose under visible light irradiation was measured. In the second test, ultraviolet light was blocked using a wavelength-cut filter. (1) Black light irradiation: TOSHIBA (registered trademark) FL10BLB 500μW measuring instrument (CUSTOM UV-340C). (2) Visible light: Halogen lamp irradiation 3,000 LX Measuring instrument (Kaise Light Meter KG-75 (385nm UV cut filter (Asahi Spectroscopic Co., Ltd.)) 【0027】 The results (decomposition time) will be explained with reference to Figure 3. In the first test (under ultraviolet light) of the photocatalytic coating agent of this first embodiment, the decomposition time was "28 minutes and 52 seconds". In the second test (under visible light), it was "17 minutes and 47 seconds". Furthermore, no precipitate was observed visually in the coating agent of this first embodiment, and there was no visible separation. In addition, the color of the coating agent was relatively less yellow and closer to white compared to the other embodiments (Embodiments 2 to 5). It also had high transparency, and light placed on the opposite side of the container containing the coating agent was clearly visible through the coating agent. 【0028】 <Second Example> The photocatalytic coating agent according to the second embodiment will now be described. A 0.5 wt% PA with pure water as the solvent, a 0.5 wt% PTA with pure water as the solvent, a 0.5 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) as the photocatalyst, and silver ion water with pure water as the solvent are mixed. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the first embodiment. 【0029】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this second example, the result of the first test (under ultraviolet light) was a decomposition time of "10 minutes and 51 seconds". The result of the second test (under visible light) was "9 minutes and 6 seconds". In addition, no precipitate was observed visually in the coating agent of this second example, and there was no visible separation. The color of the coating agent was a whitish yellow compared to the first example. Furthermore, the transparency was higher compared to the third to fifth examples, and light placed on the opposite side of the container containing the coating agent was visible through the coating agent. 【0030】 <Third Example> The photocatalytic coating agent according to the third embodiment will be described. 1.0 wt% PA in pure water as the solvent, 1.0 wt% PTA in pure water as the solvent, 1.0 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) as the photocatalyst, and silver ion water in pure water as the solvent are mixed. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the first embodiment. 【0031】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this third example, the result of the first test (under ultraviolet light) was a decomposition time of "9 minutes and 48 seconds". The result of the second test (under visible light) was "8 minutes and 18 seconds". In addition, no precipitate was observed visually in the coating agent of this third example, and there was no visible separation. Furthermore, the color of the coating agent was the strongest yellow compared to the other examples (first, second, fourth, and fifth examples). In addition, the transparency was lower compared to the first and second examples, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0032】 <Fourth Example> The photocatalytic coating agent according to the fourth embodiment will be described. A 1.5 wt% visible light sol containing 1.5 wt% PA in pure water as the solvent, 1.5 wt% PTA in pure water as the solvent, and 1.5 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the first embodiment. 【0033】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this fourth example, the decomposition time for the first test (under ultraviolet light) was "9 minutes and 19 seconds". The decomposition time for the second test (under visible light) was "7 minutes and 37 seconds". However, in this example, a very slight separation was observed after a predetermined time had elapsed following the stirring treatment of the photocatalytic coating agent. In addition, the color of the coating agent was strongly yellow, but slightly whiter compared to the third example. Furthermore, the transparency was even lower than in the third example, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0034】 <Example 5> The photocatalytic coating agent according to the fifth embodiment will now be described. A 2.0 wt% visible light sol containing 2.0 wt% PA in pure water as the solvent, 2.0 wt% PTA in pure water as the solvent, and 2.0 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the first embodiment. 【0035】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this fifth example, the result of the first test (under ultraviolet light) was a decomposition time of "9 minutes and 1 second". The result of the second test (under visible light) was "8 minutes and 18 seconds". In the fifth example, no precipitate was observed even after the predetermined time had elapsed following the stirring treatment of the photocatalytic coating agent, and no visible separation occurred. In addition, the color of the coating agent was almost white, with almost no yellow coloration. Furthermore, the transparency was even lower than in the fourth example, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0036】 <Sixth Example> The photocatalytic coating agent according to the sixth embodiment will be described. It consists of 0.1 wt% PA with pure water as the solvent, 0.1 wt% PTA with pure water as the solvent, and a photocatalytic body. A 0.1 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) is mixed with silver ion water using pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 is 6:3:1. At least one of the following methods is used for mixing and stirring: mixer, vibration, or ultrasound. 【0037】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this sixth example, the result of the first test (under ultraviolet light) was a decomposition time of "20 minutes and 55 seconds". The result of the second test (under visible light) was "11 minutes and 31 seconds". Furthermore, no precipitate was observed visually in the coating agent of this sixth example, and there was no visible separation. In addition, the color of the coating agent was relatively less yellow and closer to white compared to the other examples (examples 7 to 10). It also had high transparency, and light placed on the opposite side of the container containing the coating agent was clearly visible through the coating agent. 【0038】 <Example 7> The photocatalytic coating agent according to the 7th embodiment will now be described. A 0.5 wt% visible light sol containing 0.5 wt% PA in pure water as the solvent, 0.5 wt% PTA in pure water as the solvent, and rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 6th embodiment. 【0039】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this seventh example, the result of the first test (under ultraviolet light) was a decomposition time of "12 minutes and 24 seconds". The result of the second test (under visible light) was "9 minutes and 33 seconds". In addition, no precipitate was observed visually in the coating agent of this seventh example, and there was no visible separation. The color of the coating agent was a whitish yellow compared to the sixth example. Furthermore, the transparency was higher compared to the eighth to tenth examples, and light placed on the opposite side of the container containing the coating agent was visible through the coating agent. 【0040】 <Eighth Example> The photocatalytic coating agent according to the eighth embodiment will now be described. A 1.0 wt% visible light sol containing 1.0 wt% PA in pure water as the solvent, 1.0 wt% PTA in pure water as the solvent, and 1.0 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the sixth embodiment. 【0041】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In the first test (under ultraviolet light) of this eighth example, the decomposition time was "10 minutes and 31 seconds". In the second test (under visible light), it was "8 minutes and 20 seconds". Furthermore, no precipitate was observed visually in the coating agent of this eighth example, and there was no visible separation. In addition, the color of the coating agent was the most yellow compared to the other examples (sixth, seventh, ninth, and tenth examples). Also, the transparency was lower compared to the sixth and seventh examples, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0042】 <Example 9> The photocatalytic coating agent according to the ninth example will be described. A 1.5 wt% visible light sol containing 1.5 wt% PA in pure water as the solvent, 1.5 wt% PTA in pure water as the solvent, and 1.5 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the sixth example. 【0043】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this ninth example, the decomposition time for the first test (under ultraviolet light) was "10 minutes and 8 seconds". The result for the second test (under visible light) was "7 minutes and 35 seconds". However, in this example, after the stirring treatment of the photocatalytic coating agent and the elapsed time, no precipitate or separation was observed. Also, the color of the coating agent was a slightly yellowish white compared to the eighth example. Furthermore, the transparency was even lower than in the eighth example, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0044】 <Tenth Example> The photocatalytic coating agent according to the 10th example will be described. 2.0 wt% PA in pure water as the solvent, 2.0 wt% PTA in pure water as the solvent, 2.0 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) as the photocatalyst, and silver ion water in pure water as the solvent are mixed. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 6th example. 【0045】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 10th example, the decomposition time for the first test (under ultraviolet light) was "9 minutes and 28 seconds". The decomposition time for the second test (under visible light) was "5 minutes and 4 seconds". However, in this example, no precipitate was observed after the stirring treatment of the photocatalytic coating agent and the elapsed time, and no visible separation was observed. In addition, the color of the coating agent was almost white, with almost no yellow color observed. Furthermore, the transparency was even lower than in the fourth example, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0046】 <11th Example> The photocatalytic coating agent according to the 11th embodiment will now be described. A 0.1 wt% visible light sol containing 0.1 wt% PA in pure water as the solvent, 0.1 wt% PTA in pure water as the solvent, and 0.1 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 is 6:2:2. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0047】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 11th example, the decomposition time for the first test (under ultraviolet light) was "21 minutes and 6 seconds". The result for the second test (under visible light) was "9 minutes and 57 seconds". In addition, no precipitate was observed visually in the coating agent of this 11th example, and there was no visible separation. Furthermore, the color of the coating agent was relatively less yellow and closer to white compared to the other examples (12th to 15th examples). It also had high transparency, and light placed on the opposite side of the container containing the coating agent was clearly visible through the coating agent. 【0048】 <Example 12> The photocatalytic coating agent according to the 12th example will be described. A 0.5 wt% visible light sol containing 0.5 wt% PA in pure water as the solvent, 0.5 wt% PTA in pure water as the solvent, and rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 11th example. 【0049】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 12th example, the decomposition time for the first test (under ultraviolet light) was "9 minutes and 59 seconds". The decomposition time for the second test (under visible light) was "6 minutes and 42 seconds". In addition, although no precipitate was visible to the naked eye in the coating agent of this 12th example, there was slight separation that could be seen. Furthermore, the color of the coating agent was the most yellow compared to the other examples (6th, 7th, 9th, and 10th examples). Also, the transparency was lower compared to the 6th and 7th examples, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0050】 <Example 13> The photocatalytic coating agent according to the 13th example will be described. A 1.0 wt% visible light sol containing 1.0 wt% PA in pure water as the solvent, 1.0 wt% PTA in pure water as the solvent, and 1.0 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 11th example. 【0051】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 13th example, the decomposition time for the first test (under ultraviolet light) was "8 minutes and 21 seconds". The decomposition time for the second test (under visible light) was "6 minutes and 30 seconds". In addition, no precipitate was observed visually in the coating agent of this 13th example, and there was no visible separation. Furthermore, the color of the coating agent was almost white compared to the other examples (11th and 12th examples). In addition, the transparency was lower compared to the 11th and 12th examples, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0052】 <Example 14> The photocatalytic coating agent according to the 14th example will be described. A 1.5 wt% visible light sol containing 1.5 wt% PA in pure water as the solvent, 1.5 wt% PTA in pure water as the solvent, and 1.5 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 11th example. 【0053】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 14th example, the decomposition time for the first test (under ultraviolet light) was "8 minutes and 3 seconds". The decomposition time for the second test (under visible light) was "5 minutes and 52 seconds". However, in this example, slight separation was observed after a predetermined time had elapsed following the stirring treatment of the photocatalytic coating agent. Also, the color of the coating agent was the strongest yellow compared to the other examples (11th to 13th and 15th examples). Furthermore, although the transparency was low, light placed on the opposite side of the container containing the coating agent could be slightly seen through the coating agent in the slightly separated areas. 【0054】 <Example 15> The photocatalytic coating agent according to the 15th example will be described. A 2.0 wt% visible light sol containing 2.0 wt% PA in pure water as the solvent, 2.0 wt% PTA in pure water as the solvent, and 2.0 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 and the mixing and stirring method are the same as in the 11th example. 【0055】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this 15th example, the result of the first test (under ultraviolet light) was a decomposition time of "7 minutes and 11 seconds". The result of the second test (under visible light) was "5 minutes and 30 seconds". However, in this example, no precipitate was observed after the stirring treatment of the photocatalytic coating agent and the elapsed time, and there was no visible separation. Also, the color of the coating agent was almost white, with almost no yellow color observed. Furthermore, the transparency was even lower than in the 13th example, and light placed on the opposite side of the container containing the coating agent could not be seen through the coating agent. 【0056】 <Comparative Example 1> The photocatalytic coating agent used in Comparative Example 1 will be described below. A 0.05 wt% PA solution with pure water as the solvent, a 0.05 wt% PTA solution with pure water as the solvent, a 0.05 wt% visible light sol using platinum-supported rutile titanium dioxide (PtTiO2) as the photocatalyst, and silver ion water with pure water as the solvent are mixed. The mixing ratio of PA:PTA:PtTiO2 is 5:4:1. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0057】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this Comparative Example 1, the result of the first test (under ultraviolet light) was that the decomposition time "exceeded 90 minutes". The second test (under visible light) also "exceeded 90 minutes". The same result was obtained even when the mixing ratio of PA:PTA:PtTiO2 was 6:2:2. Furthermore, no precipitate was observed visually in the coating agent of this Comparative Example 1, and there was no visible separation. In addition, the color of the coating agent was relatively less yellow and closer to white compared to the examples of the present invention described above (for example, the second to fifth examples). It also had high transparency, and light placed on the opposite side of the container containing the coating agent was clearly visible through the coating agent. 【0058】 <Comparative Example 2> The photocatalytic coating agent used in Comparative Example 2 will now be described. A 2.5 wt% visible light sol containing 2.5 wt% PA in pure water as the solvent, 2.5 wt% PTA in pure water as the solvent, and 2.5 wt% rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst, is mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 is 5:4:1. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0059】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. The result of the first test (under ultraviolet light) in Comparative Example 2 was "8 minutes and 5 seconds". The result of the second test (under visible light) was "6 minutes and 7 seconds". However, in Comparative Example 2, no visible precipitate was observed after the predetermined time had elapsed following the stirring treatment of the photocatalytic coating agent, and there was no visible separation. This result was the same even when the mixing ratio of PA:PTA:PtTiO2 was 6:2:2. In addition, the color of the coating agent was relatively less yellow and closer to white compared to the other examples (Examples 12 to 15). It also had high transparency, and light placed on the opposite side of the container holding the coating agent was clearly visible through the coating agent. 【0060】 <Comparative Example 3> The photocatalytic coating agent used in Comparative Example 3 will now be described. A 0.5 wt% visible light sol containing 0.5 wt% PA in pure water as the solvent, 0.5 wt% PTA in pure water as the solvent, and rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 is 7:0.5:2.5. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0061】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this Comparative Example 3, the result of the first test (under ultraviolet light) was a decomposition time of "7 minutes and 15 seconds". The result of the second test (under visible light) was "6 minutes and 23 seconds". These results were similar even when the solid content concentration of PA was 2.0%. In this Comparative Example 3, clear separation occurred, and the dispersant layer and the precipitate layer were clearly separated. 【0062】 <Comparative Example 4> The photocatalytic coating agent used in Comparative Example 4 will now be described. A 0.5 wt% visible light sol containing 0.5 wt% PA in pure water as the solvent, 0.5 wt% PTA in pure water as the solvent, and rutile-type titanium dioxide (PtTiO2) supported with platinum as the photocatalyst are mixed with silver ion water in pure water as the solvent. The mixing ratio of PA:PTA:PtTiO2 is 7:2.8:0.2. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0063】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this Comparative Example 4, the decomposition time for the first test (under ultraviolet light) was "9 minutes and 45 seconds". The decomposition time for the second test (under visible light) was "7 minutes and 30 seconds". These results were similar even when the solid content concentration of PtTiO2 was 2.0%. In addition, the color of the coating agent was relatively more yellow compared to the other comparative examples (Comparative Examples 1-3 and 5). Furthermore, it had high transparency, and light placed on the opposite side of the container containing the coating agent was clearly visible through the coating agent. 【0064】 <Comparative Example 5> The photocatalytic coating agent used in Comparative Example 5 will now be described. A 0.5 wt% PA solution with pure water as the solvent, a 0.5 wt% PTA solution with pure water as the solvent, a 1.0 wt% visible light sol using platinum-supported rutile-type titanium dioxide (PtTiO2) as the photocatalyst, and silver ion water with pure water as the solvent are mixed. The mixing ratio of PA:PTA:PtTiO2 is 5:4:1. At least one of the following methods is used for mixing and stirring: a mixer, vibration, or ultrasound. 【0065】 The photocatalytic coating agent prepared as described above was subjected to the same two tests (the first and second tests) as in the first example, on test pieces prepared in the same manner as in the first example. In this comparative example 5, the result of the first test (under ultraviolet light) was a decomposition time of "9 minutes and 9 seconds". The result of the second test (under visible light) was "8 minutes and 10 seconds". However, in this comparative example, slight separation was observed after a predetermined time had elapsed following the stirring treatment of the photocatalytic coating agent. As described above, increasing the mixing ratio of the visible light sol tends to lead to separation and precipitation. Furthermore, while increasing the wt% speeds up the decomposition time, it also tends to cause clouding. For example, when a coating agent is sprayed, depending on the experience level of the user, white marks may remain on the object, potentially reducing its aesthetic appeal (see Figure 3). In the experimental data above, the retirement time for visible light was shorter than that for ultraviolet light. However, this does not necessarily mean that the organism reacts better to visible light than to ultraviolet light; factors such as light intensity, humidity, and temperature also influence the results. 【0066】 [State of the photocatalyst in the second example and comparative example 5] Each of the above embodiments and comparative examples The photocatalytic material in the photocatalytic coating agent was observed using an electron microscope. The results are described for each example. 【0067】 <Second Example> When the bonding state of PTA, PA, and PtTiO2 in the photocatalytic coating agent of the second example was observed, it was found that PTA, PA, and PtTiO2 were bonded in approximately a one-to-one ratio, indicating good dispersibility. 【0068】 <Comparative Example 5> The binding state of PTA, PA, and PtTiO2 in the photocatalytic coating agent of Comparative Example 5 was observed. Due to the higher concentration of PtTiO2 compared to PTA and PA, the dispersibility was worse than in Example 2, with many unbound Pt particles being observed. It can be said that... 【0069】 [Effects / Effects] In the above-described example, the photocatalytic coating agent has its solid content concentration adjusted in each solution of PA, PTA, and visible light sol. This makes it possible to maximize the photocatalytic function while reducing the amount of photocatalytic material that does not mix completely in the dispersion medium. As a result, it is possible to prevent a decrease in dispersion stability. Furthermore, test results show that when the solid content concentration of PTA, PA, and PtTiO2 is 1.0 wt% or less, turbidity is reduced, separation is less likely to occur, and dispersion stability is higher. It was also found that dispersibility is improved when the difference in solid content concentration of PTA, PA, and PtTiO2 is within 0.2 wt%. Furthermore, it was found that dispersibility is further improved when the difference in solid content concentration is within 0.1 wt%. In addition, even when the difference in solid content concentration is within 0.3 wt%, dispersibility is generally good. Note that "the wt% are substantially the same" may mean, for example, that the difference in solid content concentration is within 0.1 wt%. Furthermore, it was found that separation becomes easier as the proportion of visible light sols, such as platinum-supported titanium oxide, increases. 【0070】 While embodiments of this invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

Claims

[Claim 1] It contains peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol, and furthermore, the solid content concentration of each of the peroxo-modified anatasesol, peroxotitanic acid aqueous solution, and visible light sol is 0.1 to 2.0 wt%. The difference in solid content concentration between the two is 0.2 wt%. A photocatalytic coating agent characterized by the following features. [Claim 2] The photocatalytic coating agent according to claim 1, characterized in that the visible light sol contains platinum-supported titanium oxide. [Claim 3] The photocatalytic coating agent according to claim 2, characterized in that the wt% of peroxo-modified anatase sol, peroxotitanic acid, and visible light sol are substantially the same. [Claim 4] The photocatalytic coating agent according to any one of claims 1 to 3, further characterized by containing silver. [Claim 5] A step of adjusting the solid content concentration in each of the peroxo-modified anatase sol, peroxotitanic acid aqueous solution, and visible light sol to a range of 0.1 to 2.0 wt%, This includes a step of mixing the peroxo-modified anatase sol, an aqueous peroxotitanic acid solution, and a visible light sol. The difference in solid content concentration between each is 0.2 wt%. A method for producing a photocatalytic coating agent. [Claim 6] The photocatalyst according to claim 5, characterized in that the visible light sol contains platinum-supported titanium oxide. A method for manufacturing a coating agent. [Claim 7] The wt% of peroxo-modified anatase sol, peroxotitanic acid aqueous solution, and visible light sol are substantially the same. Production of the photocatalytic coating agent according to feature 5 method.

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