Photocatalyst-coated substrate

Abstract

To provide a substrate with a photocatalyst having high abrasion resistance and photocatalytic performance.SOLUTION: A photocatalyst coating liquid contains photocatalyst particles and binder particles. The photocatalyst particles have positive or negative zeta potential in an acidic region. The binder particles each contain a resin-containing core and a shell that is on the surface of the core and has an inorganic compound having a reactive group, and have zeta potential that is reversed polarity of the zeta potential of the photocatalyst particles in the acidic region. The photocatalyst coating liquid is applied to a substrate and forms a coating film through a drying process.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a photocatalyst coating liquid, a substrate with a photocatalyst, and a method for producing a substrate with a photocatalyst. [Background technology]

[0002] In general, photocatalysts have the characteristic of breaking organic bonds and decomposing many organic substances. Therefore, it is known that when a photocatalyst layer is formed on a substrate, if the substrate is an organic substance, the substrate is decomposed by the photocatalytic action.

[0003] In addition, the binder contained in the photocatalyst layer to fix the photocatalyst particles to the substrate must be one that is not easily decomposed by photocatalysis. If an organic resin is used as the binder, the resin binder is decomposed by photocatalysis, and the adhesion of the photocatalyst particles in the photocatalyst layer decreases, causing them to fall off from the substrate (a phenomenon known as chalking). This leads to a deterioration in the abrasion resistance and water resistance of the photocatalyst layer, as well as a decrease in catalytic performance.

[0004] On the other hand, if an inorganic material that is not easily decomposed by photocatalysis is used for the binder, the adhesive strength of the photocatalyst particles in the photocatalyst layer does not decrease, but there is a problem that the adhesion between the photocatalyst layer and the substrate is significantly reduced unless treatment such as high-temperature baking is performed. For this reason, if the substrate is made of resin, high-temperature treatment is not possible, the adhesive strength with the inorganic material binder is weak, and it is difficult to fully satisfy the wear resistance and water resistance of the photocatalyst layer.

[0005] Furthermore, there is generally a problem that particles with different zeta potentials will aggregate when mixed in a solution.

[0006] In addition, in a photocatalyst layer formed by applying a coating liquid containing a mixture of a binder and photocatalyst particles to a substrate, if the photocatalyst particles are buried in the binder, the buried photocatalyst particles will lose their photocatalytic activity, and the number of active photocatalyst particles on the surface of the photocatalyst layer will decrease. In that case, the density of particles with photocatalytic activity will be low, and the photocatalytic function cannot be fully exerted. For example, when decomposing an odorous gas with a photocatalyst, the odorous gas needs to come into contact with or be very close to the photocatalyst, but the photocatalyst particles buried in the binder do not contribute to the decomposition. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-310039 [Patent Document 2] Patent No. 3759651 [Patent Document 3] Patent No. 3831457 [Non-patent literature]

[0008] [Non-Patent Document 1] October 15, 2003, published by Gijutsuhyoronsha, by Fumiaki Otani, A book that explains the mechanism of photocatalysis Summary of the Invention [Problem to be solved by the invention]

[0009] An object of an embodiment of the present invention is to provide a photocatalyst-coated substrate having good abrasion resistance and photocatalytic performance. [Means for solving the problem]

[0010] According to an embodiment, A photocatalyst-containing substrate in which a photocatalyst coating liquid is applied onto a substrate, The photocatalyst coating liquid comprises photocatalyst particles having a positive or negative zeta potential in an acidic range, A binder particle having a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particles in an acidic range, the binder particle having a core containing a resin and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, the binder particle having a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particles in an acidic range, the binder particle having a pH of 2 to 6, The binder particles undergo a polycondensation reaction with the base material. And, The substrate is at least one of polypropylene, polyethylene terephthalate, polystyrene, glass, polymethyl methacrylate, cotton thread, and polyethylene nonwoven fabric. A photocatalyst-bearing substrate is provided. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing the configuration of a photocatalyst-attached substrate according to an embodiment. [Diagram 2] FIG. 2 is a graph showing the zeta potential of a resin. [Diagram 3] FIG. 2 is a graph showing the zeta potential of WO3 particles. [Figure 4] FIG. 2 is a graph showing the zeta potential of core-shell type binder particles. [Diagram 5] FIG. 2 is a schematic diagram showing a dispersion state of particles in a photocatalyst coating liquid. [Figure 6] 3 is a schematic diagram showing the state of particles before a coating film of a photocatalyst coating liquid dries and hardens. FIG. [Figure 7] FIG. 2 is a schematic diagram showing the state of particles after a coating film of a photocatalyst coating liquid has dried and solidified. [Figure 8] FIG. 2 is a graph showing the photocatalytic decomposition performance of a substrate with a photocatalyst. [Figure 9] FIG. 13 is a photograph showing the criteria for determining the transfer level. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The photocatalyst coating liquid according to the embodiment is a photocatalyst coating liquid that is applied to a substrate and dried to form a coating film on the substrate, and contains photocatalyst particles and binder particles.

[0013] The photocatalyst particles used in the photocatalyst coating liquid have a positive or negative zeta potential in the acidic range.

[0014] The binder particles used in the photocatalyst coating liquid are of the core-shell type consisting of a core and a shell that generally surrounds the core, the core being made of a resin and the shell being made of an inorganic compound.

[0015] The inorganic compound used in the shell of the binder particle has a reactive group.

[0016] The binder particles have a zeta potential of opposite polarity to the zeta potential of the photocatalyst particles in the acidic range.

[0017] Moreover, the method for producing a photocatalyst-attached substrate according to the embodiment is characterized in that the above-mentioned photocatalyst coating liquid is applied onto a substrate to form a photocatalyst layer.

[0018] Furthermore, the photocatalyst-attached substrate includes a substrate, and a photocatalyst layer formed by applying the above-mentioned photocatalyst coating liquid onto the substrate and then carrying out a drying process to form a coating film.

[0019] FIG. 1 shows a cross-sectional view illustrating an example of the configuration of a photocatalyst-attached substrate according to an embodiment.

[0020] As shown in the figure, this photocatalyst-attached substrate 70 has a substrate 1 and a photocatalyst layer 60 formed on the substrate 1.

[0021] When the photocatalyst coating solution according to the embodiment is applied to a substrate and dried, the inorganic compound on the surface of the binder particles comes into contact with the photocatalyst, so that the binder particles are not decomposed by the photocatalyst. Therefore, a photocatalyst layer with high abrasion resistance can be formed.

[0022] In addition, when a photocatalyst layer is formed using the photocatalyst coating solution according to the embodiment, the reactive group in the shell of the binder bonds with the substrate, so that the adhesive strength can be maintained. In addition, when the binder particles enter the concave portion of the substrate, and also in the convex portion, when the solvent in the solution evaporates to dryness, the reactive group in the shell of the binder particles undergoes polycondensation reaction with the substrate and also with the resin in the core, so that the binder particles can be firmly fixed to both the concave and convex portions of the substrate.

[0023] Furthermore, according to the photocatalyst coating liquid according to the embodiment, the zeta potential of the binder resin particles and the zeta potential of the photocatalyst particles have opposite polarities.

[0024] For example, the zeta potential of the binder particles can be made positive, and the zeta potential of the photocatalyst particles can be made negative. The zeta potential of many resins that serve as base materials is negative in the pH range of 3 to 6.

[0025] FIG. 2 is a graph showing the zeta potential of resins that can be used as substrates.

[0026] In the figure, 101 indicates graphs of polypropylene, 102 indicates graphs of polyethylene terephthalate, 103 indicates graphs of polystyrene, 104 indicates graphs of vinyl chloride, 105 indicates graphs of glass, 106 indicates graphs of polymethyl methacrylate, 107 indicates graphs of cotton thread, and 108 indicates graphs of polyethylene nonwoven fabric.

[0027] As shown in the figure, for example, in the acidic range of pH 4 to 6, the zeta potential is negative for all materials except PET.

[0028] In this case, the zeta potential is measured using a zeta potential / particle size measurement system ELSZ manufactured by Otsuka Electronics Co., Ltd.

[0029] FIG. 3 is a graph showing the zeta potential of WO3 particles as photocatalyst particles that can be used in the embodiment.

[0030] In the figure, 201 indicates a graph showing the relationship between the zeta potential of monoclinic WO3 particles and pH, and 202 indicates a graph showing the relationship between the zeta potential of triclinic WO3 particles and pH.

[0031] As shown in the figure, for example, in the acidic range of pH 4 to 6, the zeta potential of WO3 particles is negative.

[0032] FIG. 4 shows an example of the zeta potential of binder particles that can be used in the embodiment.

[0033] Here, binder particles having an acrylic resin core and a shell made of active silicic acid are used as the binder particles, and in the figure, 301 shows a graph showing the relationship between the zeta potential and pH.

[0034] As shown in the figure, for example, in the acidic range of pH 4 to 6, the zeta potential of the core-shell type binder particles is positive.

[0035] When the photocatalyst solution according to the embodiment is applied to a resin substrate, the binder particles with a positive zeta potential are attracted to the substrate side with a negative zeta potential, increasing the binder particle density, while the photocatalyst particles with a negative zeta potential are distributed in large amounts on the surface of the photocatalyst layer away from the substrate above the binder. Furthermore, the photocatalyst layer obtained by drying the coating has a configuration in which the binder particle concentration is high on the substrate side surface and the photocatalyst particle concentration is high on the surface opposite to the substrate side surface.

[0036] As the photocatalyst particles, for example, particles of at least one metal compound of titanium oxide, zinc oxide, tungsten oxide, niobium oxide, or tin oxide can be used.

[0037] The resin used in the core may include at least one of a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include acrylic, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polyamide, polybutylene terephthalate, ABS resin, and acetal resin.

[0038] The thermosetting resin may include polyurethane, unsaturated polyester, phenolic resin, melamine resin, epoxy resin, or urea resin.

[0039] Elements that can be used in inorganic compounds having reactive groups include, for example, transition elements, elements of groups 12, 13, or 14 of the periodic table.

[0040] The transition elements may, for example, be titanium, cobalt, nickel or zirconium.

[0041] An example of an element in group 12 of the periodic table is zinc.

[0042] The Group 13 element may be aluminum or indium.

[0043] Group 14 elements include silicon and tin.

[0044] Examples of inorganic compounds having a reactive group include oxides, hydroxides, oxide hydroxides, oxycarbonates, oxynitrates, hydrochlorides, methoxides, ethoxides, isopropoxides of the above transition elements and elements of Group 12, 13, or 14 of the periodic table, and hydrolysis polycondensates of these alkoxides, titanate coupling agents, silane coupling agents, and siloxanes.

[0045] Moreover, the photocatalyst coating liquid according to the embodiment may further contain a dispersion stabilizer.

[0046] As the dispersion stabilizer, compounds having a carbonyl group, such as acetylacetone, diacetone alcohol, zirconium oxide acetate, aluminum acetate, and ethylenediaminetetraacetic acid, can be used.

[0047] When the number of carbonyl groups is n, the dispersion stabilizer can be added in an amount of 0.1 / n mole to 4 / n mole per mole of the solid content of the photocatalyst particles.

[0048] The dispersion stabilizer can mainly coordinate the carbonyl group to the metal element of the photocatalyst particle when the binder component and the photocatalyst are mixed. According to the embodiment, the potential of the coordination part of the formed photocatalyst particle becomes positive, so that repulsion occurs between the binder particle and the photocatalyst particle, and even if the binder liquid and the photocatalyst particle slurry are mixed, the binder particle and the photocatalyst particle having different zeta potentials can be prevented from agglomerating within the practical time of the coating work. If the amount of the dispersion stabilizer is too small, the coordination amount becomes small and it is ineffective, and if it is too large, it hinders the binding between the binder and the photocatalyst particle when it is applied to the base material. As a result of the inventors' earnest study, it was found that the amount of the dispersion stabilizer added is preferably within 0.1 / n mole to 4 / n mole, where n is the number of carbonyl groups, for 1 mole of the photocatalyst solid content.

[0049] FIG. 5 is a schematic diagram showing the dispersion state of particles in a photocatalyst coating liquid.

[0050] For example, a photocatalyst coating liquid 40 can be prepared by mixing a binder liquid containing binder particles and a solvent with a slurry in which photocatalyst particles are dispersed in the solvent. As shown in the figure, the photocatalyst coating liquid 40 contains a solvent 30, binder particles 10 dispersed in the solvent 30, and photocatalyst particles 20. The binder particles 10 have a resin core 11 and an inorganic compound shell 12 provided around the resin core 11. For example, when the zeta potential of the binder particles 10 is positive and the zeta potential of the photocatalyst particles is negative in an acidic region of pH 3 to 6, coordination occurs with the carbonyl group of the dispersion stabilizer 21 with the metal element of the photocatalyst particles 20 on the surface of the photocatalyst particles 20. As a result, the potential of the coordination part on the surface of the photocatalyst particles 20 becomes positive. Due to the positive potential of this coordination part, repulsion occurs at the coordination part between the binder particles 10 and the photocatalyst particles 20, which have a positive zeta potential, and the binder particles 10 and the photocatalyst particles 20 can be dispersed while preventing aggregation.

[0051] FIG. 6 is a schematic diagram showing the state of particles before the coating film of the photocatalyst coating solution dries and hardens.

[0052] When the zeta potential of the resin used as the substrate is negative, when a photocatalytic coating liquid 40 is applied onto this substrate 1, in the coating film 50 before drying, as shown in the figure, the binder particles 10 with a positive zeta potential are attracted to the substrate 1 side, the binder particle density increases, and the photocatalytic particles 20 with a negative zeta potential are distributed in large numbers on the surface of the coating film 50 away from the substrate 1.

[0053] FIG. 7 is a schematic diagram showing the state of particles after the coating film of the photocatalyst coating solution has dried and hardened.

[0054] Both the binder liquid and the photocatalyst slurry are acidic, and the solvent is also acidic, so the pH drops as the solvent evaporates. As a result, the zeta potential of the binder particles 10 becomes higher, and the binder particles 10 are attracted to the substrate 1. On the other hand, the zeta potential of the photocatalyst particles 20 also changes from negative to close to zero potential, and they surround the binder particles 10 and aggregate. When the acidity increases during the solvent evaporation process, the zeta potential of the resin substrate 1 also changes to the positive direction, but during the drying process, a polycondensation reaction between the binder particles 10 and the substrate 1 begins, and a polycondensation polymer 13 is formed, so that the binder 10' with the polycondensation polymer 13 formed does not leave the substrate 1, and as a result, as shown in FIG. 7, the photocatalyst layer 60 obtained by drying the coating film 50 can be formed to have a film structure in which the binder concentration on the substrate 1 surface is high and the photocatalyst particles 20 on the photocatalyst layer 60 surface are high. In addition, the dispersion stabilizer 21 that has been forming the complex also simultaneously undergoes a polycondensation reaction, and therefore acts as a coupling agent between the binder 10' and the photocatalyst particles 20. As a result, the photocatalyst particles 20 are not buried in the binder 10', and the density of the photocatalyst particles 20 on the surface of the photocatalyst layer 60 is high, and a coating film having highly active photocatalytic performance can be formed.

[0055] The solid content of the binder particles used in the embodiment can be 4% by weight or more, preferably 20 to 40% by weight, based on the total weight of the solid content of the photocatalyst particles and the solid content of the binder particles.

[0056] The photocatalyst particles used in the embodiment may have a volume average particle size of 10 to 500 nm.

[0057] The binder particles used in the embodiment may have a volume average particle size of 50 to 300 nm.

[0058] The volume average particle size of the binder particles used in the embodiment is preferably equal to or larger than the volume average particle size of the photocatalyst particles.

[0059] The volume average particle size is measured using a zeta potential / particle size measurement system ELSZ manufactured by Otsuka Electronics Co., Ltd.

[0060] The photocatalyst coating liquid used in the embodiment may further include a dispersion liquid containing at least one of water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, hypochlorous acid water, acetic acid, lactic acid, formic acid, butyric acid, hydrochloric acid, nitric acid, sulfuric acid, or various organic acids.

[0061] The photocatalyst coating solution may have a pH of 2-6, preferably 4-6. EXAMPLES

[0062] The following examples are provided to more specifically explain the embodiments.

[0063] Example 1 The binder used was a cationic binder containing an acrylic resin as the core and silicon oxide as the shell.

[0064] This cationic binder can be produced, for example, by a method including the steps of forming an acrylic resin emulsion, applying and reacting a raw material that becomes silicon oxide, and laminating the silicon oxide as a shell. If necessary, a surface treatment can be performed to impart cationic properties to the silicon oxide shell.

[0065] The average particle size D50 was 100 nm. The binder liquid was prepared using mainly water as the solvent.

[0066] A WO3 fine particle slurry was prepared by dispersing WO3 fine particles having a volume average particle diameter of 100 nm mainly in water.

[0067] Diacetone alcohol was prepared as a dispersion stabilizer.

[0068] A photocatalyst coating liquid was prepared by mixing 10 parts by weight of WO3 with 5 parts by weight of binder and 10 parts by weight of diacetone alcohol as a dispersion stabilizer in a solid ratio, and adding 475 parts by weight of water as a dispersion liquid.

[0069] When the number of carboxyl groups is n, the dispersion stabilizer is contained in an amount of 0.5 / n moles per mole of the solid content of the photocatalyst particles.

[0070] The solid content of the obtained photocatalyst coating liquid was 5% by weight.

[0071] The photocatalyst coating solution thus obtained had a pH of 3.5.

[0072] To change the pH, you can use hydrochloric acid, acetic acid, sodium hydroxide, or sodium citrate. etc. can be added.

[0073] Photocatalytic coating liquid is applied to the PS substrate at a coating weight of 0.5 g / m 2 The resulting mixture was dried to form a substrate with a photocatalyst.

[0074] The photocatalytic decomposition performance and film strength of the obtained substrate with photocatalyst were measured.

[0075] Measurement of photocatalytic decomposition performance Inject acetaldehyde into the light-exposure sealed container to a concentration of 10 ppm, and apply a coating weight of 0.5 g / m 2The photocatalyst-coated substrate was placed in the room, and 6000 lux of light from a broadband fluorescent lamp (symbol W) was continuously irradiated onto the photocatalyst-coated substrate through a UV sharp cut filter specified as Type B by JIS R1750. The acetaldehyde concentration was measured every 30 minutes using a Gastec gas sampler GV-110 and a Gastec formaldehyde detector No. 91D.

[0076] FIG. 8 is a graph showing the photocatalytic decomposition performance of the substrate with photocatalyst.

[0077] In the figure, 401 denotes a graph showing the relationship between the elapsed time and the concentration of acetaldehyde.

[0078] 402 shows a graph showing the relationship between the elapsed time and the reduction rate (volume %) of acetaldehyde.

[0079] As shown in the figure, acetaldehyde can be decomposed and reduced by continuously irradiating the obtained photocatalyst substrate with light. It can also be seen that the reduction rate of acetaldehyde decreases with time.

[0080] Measuring film strength The film strength, which is an index of abrasion resistance, is measured as follows.

[0081] The obtained substrate with photocatalyst was subjected to a strength test by a black cloth friction test.

[0082] Prepare black wool cloth (product number: 73029-2021 / 48 Saxony) and place it opposite the photocatalyst layer of the photocatalyst-coated substrate. 2 Pressurize the substrate side with a pressure of 1000 MPa to transfer the photocatalyst layer onto the black wool cloth.

[0083] The transfer level of the photocatalyst layer is judged using a criterion.

[0084] FIG. 9 shows photographs illustrating the criteria for determining the transfer level.

[0085] In the figure, level 5 indicates a state where the black cloth has turned white to the point where the black parts are no longer visible, and a significant amount of the photocatalyst layer has been transferred. Level 3 indicates a state where the photocatalyst layer has been transferred to white. Level 4 is between level 5 and level 3, and indicates a state where the photocatalyst layer has been transferred to white. Level 2 indicates a state where the photocatalyst layer has been transferred to white if you look closely with the naked eye. Level 1 indicates a state where no transfer is visible with the naked eye.

[0086] The criteria are: level 3 to 5 is poor, level 2 is good, and level 1 is excellent.

[0087] When the transfer level of the black cloth was judged using this criterion, the transfer level of the film strength of the substrate with photocatalyst in Example 1 was 1.

[0088] Example 2 A photocatalyst coating solution was prepared in the same manner as in Example 1, except that the weight ratio of the binder to 10 parts by weight of WO3 was changed.

[0089] The resulting photocatalyst coating liquid had a pH of 3.4.

[0090] Photocatalytic coating liquid is applied to the PS substrate at a coating weight of 0.5 g / m 2 The resulting mixture was dried to form a substrate with a photocatalyst.

[0091] The photocatalytic performance and the transfer level of the black cloth are shown in Table 1 below.

[0092] [Table 1]

[0093] From Table 1 above, it can be seen that when the weight ratio of binder to WO3 (10 parts by weight) is 2 to 7 parts by weight, both photocatalytic performance and film strength are good.

[0094] Example 3 Photocatalyst coating solutions were prepared in the same manner as in Example 1, except that binders having different types of cores and various zeta potentials were used.

[0095] The resulting photocatalyst coating liquid had a pH of 3.6.

[0096] Photocatalytic coating liquid is applied to the PS substrate at a coating weight of 0.5 g / m 2 The resulting mixture was dried to form a substrate with a photocatalyst.

[0097] The photocatalytic decomposition performance and film strength of the obtained substrate with photocatalyst were measured.

[0098] The results of photocatalytic performance and the level of transfer of black cloth are shown in Table 2 below.

[0099] [Table 2]

[0100] In the above table, the shells of binders 1 to 5 are silicon oxides, and the cores are as follows:

[0101] Binder 1 Core: Amphoteric latex Binder 2 Core: Polymethacrylic acid Binder 3 Core: Polypropylene Binder 4 Core: Polystyrene Binder 5 Core: Epoxy As shown in the above table, when the zeta potential of the substrate is negative and the zeta potential of the photocatalyst particles is negative, if the zeta potential of the binder is positive, the photocatalytic performance and film strength are good.

[0102] Example 4 The photocatalyst coating solution was prepared in the same manner as in Example 1, except that the binder used was the same as in Example 1 except that the average particle diameter was different, and the weight ratio of the binder to 10 parts by weight of WO3 was changed within the range of 2 to 7 parts by weight.

[0103] The resulting photocatalyst coating liquid had a pH of 3.8.

[0104] Photocatalytic coating liquid is applied to the PS substrate at a coating weight of 0.5 g / m 2 The resulting mixture was dried to form a substrate with a photocatalyst.

[0105] The photocatalytic performance and the transfer level of the black cloth are shown in Table 3 below.

[0106] [Table 3]

[0107] As shown in Table 3 above, when the average particle size of the core-shell type binder is 50 to 200 nm, the photocatalytic performance and film strength are good when the weight ratio of the binder to 10 parts by weight of WO3 is in the range of 2 to 7 parts by weight.

[0108] Although some embodiments of the present invention have been described, these embodiments are presented as examples 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 modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. The following is an appendix to the inventions described in the claims of the application prior to this original application (Patent Application No. 2017-180712) immediately prior to the division. [Appendix 1] [1] A photocatalytic coating liquid that is applied to a substrate and dried to form a coating film on the substrate, Photocatalyst particles having a positive or negative zeta potential in an acidic range; a binder particle including a core containing a resin and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, the binder particle having a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particle in an acidic range; A photocatalyst coating solution comprising a dispersion stabilizer. [2] The photocatalyst coating solution according to [1], wherein the dispersion stabilizer is at least one of acetylacetone, diacetone alcohol, zirconium acetate, and aluminum acetate. [3] The photocatalyst coating liquid according to [1] or [2], wherein the dispersion stabilizer is contained in an amount of 0.1 / n mole to 2 / n mole per mole of solid content of the photocatalyst particles, where n is the number of C=O groups. [4] A photocatalytic coating liquid that is applied to a substrate and dried to form a coating film on the substrate, Photocatalyst particles having a positive or negative zeta potential in an acidic range; A photocatalyst coating solution having a pH of 2 to 6, comprising a core containing a resin, and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, and comprising binder particles having a zeta potential of opposite polarity to that of the photocatalyst particles in the acidic range. [5] The photocatalyst coating solution according to any one of [1] to [4], wherein the photocatalyst particles are particles of at least one metal compound selected from the group consisting of titanium oxide, zinc oxide, tungsten oxide, niobium oxide, and tin oxide. [6] The resin includes at least one of a thermoplastic resin and a thermosetting resin; The thermoplastic resin includes at least one of acrylic, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polyamide, polybutylene terephthalate, ABS resin, and acetal resin; The photocatalyst coating liquid according to any one of [1] to [5], wherein the thermosetting resin contains at least one of polyurethane, unsaturated polyester, phenolic resin, melamine resin, epoxy resin, and urea resin. [7] The photocatalyst coating solution according to any one of [1] to [6], wherein the inorganic compound having a reactive group contains at least one of a transition element and an element in Group 12, 13, or 14 of the periodic table. [8] The photocatalytic coating solution according to [7], wherein the transition element includes at least one of titanium and zirconium, the Group 12 element of the periodic table includes zinc, the Group 13 element includes aluminum or indium, and the Group 14 element includes silicon or tin. [9] The photocatalytic coating solution according to [8], wherein the inorganic compound having a reactive group is at least one of oxides, hydroxides, oxide hydroxides, oxycarbonates, oxynitrates, hydrochlorides, methoxides, ethoxides, isopropoxides of the transition elements, the Group 12 elements, the Group 13 elements, or the Group 14 elements of the periodic table, and hydrolysis polycondensates of these alkoxides, titanate coupling agents, silane coupling agents, and siloxanes.

[10] The photocatalyst coating solution according to any one of [1] to [9], wherein the solid content of the binder particles is 4% by weight or more based on the total weight of the solid content of the photocatalyst particles and the solid content of the binder particles.

[11] The photocatalyst coating solution according to any one of [1] to

[10] , wherein the photocatalyst particles have a volume average particle size of 10 to 500 nm.

[12] The photocatalyst coating solution according to any one of [1] to

[11] , wherein the binder particles have a volume average particle size of 50 to 300 nm.

[13] The photocatalyst coating solution according to any one of [1] to

[12] , wherein the volume average particle diameter of the binder particles is equal to or larger than the volume average particle diameter of the photocatalyst particles.

[14] The photocatalyst coating solution according to any one of [1] to

[13] , further comprising a dispersion liquid containing at least one of water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, hypochlorous acid water, acetic acid, lactic acid, formic acid, butyric acid, hydrochloric acid, nitric acid, sulfuric acid, and various organic acids.

[15] The photocatalyst coating solution according to any one of [1] to

[14] , wherein the photocatalyst particles have a negative zeta potential in an acidic range, and the binder particles have a positive zeta potential in an acidic range.

[16] A method for producing a substrate with a photocatalyst, comprising applying the photocatalyst coating liquid according to any one of [1] to

[15] onto a substrate to form a photocatalyst layer.

[17] The method according to

[16] , wherein the substrate has a negative surface zeta potential.

[18] The formation of the photocatalyst layer is forming a coating film of the photocatalyst coating liquid, and attracting binder particles having a positive zeta potential in the coating film to the substrate side having a negative surface zeta potential, thereby increasing the density of the binder particles on the substrate side; a solvent in the coating film of the photocatalyst coating liquid is evaporated to further increase the zeta potential of the binder particles, thereby attracting the binder particles more strongly to the substrate side and causing them to aggregate; The method according to

[17] , comprising drying a coating film of the photocatalyst coating liquid and carrying out a polycondensation reaction between the binder particles and the base material.

[19] A substrate with a photocatalyst, comprising: a substrate; and a photocatalyst layer formed by applying the photocatalyst coating solution according to any one of [1] to

[15] onto the substrate and then carrying out a drying process to form a coating film.

[20] The photocatalyst particles have a positive or negative zeta potential in the acidic range in the photocatalyst coating liquid, and the binder particles have a zeta potential of opposite polarity to the zeta potential of the photocatalyst particles when dispersed in an acidic solution.

[19] A photocatalyst-containing substrate according to the present invention. [twenty one] The photocatalyst-coated substrate according to

[19] or

[20] , wherein the photocatalyst layer has a high concentration of the binder particles on the surface facing the substrate, and a high concentration of the photocatalyst particles on the surface opposite the surface facing the substrate. [twenty two] The photocatalyst-attached substrate according to any one of

[19] to

[21] , wherein the substrate has a negative surface zeta potential. In addition, the invention described in the claims of the original application (Patent Application No. 2022-38099) prior to this application immediately prior to the division is appended below. [Appendix 2] [1] A method for producing a photocatalyst coating liquid, which is applied to a substrate and dried to form a coating film on the substrate, comprising the steps of: Photocatalyst particles having a positive or negative zeta potential in an acidic range; A step of dispersing binder particles, which include a core containing a resin and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, and have a zeta potential of opposite polarity to the zeta potential of the photocatalyst particles in an acidic range, in a dispersion liquid to obtain a dispersion system; A method for producing a photocatalyst coating liquid, comprising a step of mixing the dispersion with a dispersion stabilizer. [2] The method for producing a photocatalyst coating liquid according to [1], wherein the dispersion stabilizer is at least one of acetylacetone, diacetone alcohol, zirconium acetate, and aluminum acetate. [3] The method for producing a photocatalyst coating liquid according to [1] or [2], wherein the dispersion stabilizer is contained in an amount of 0.1 / n mole to 2 / n mole per mole of solid content of the photocatalyst particles, where n is the number of C=O groups. [4] A method for producing a photocatalyst coating liquid, which is applied to a substrate and dried to form a coating film on the substrate, comprising the steps of: Photocatalyst particles having a positive or negative zeta potential in an acidic range; A method for producing a photocatalyst coating liquid, comprising: dispersing a core containing a resin; and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, and binder particles having a zeta potential of opposite polarity to that of the photocatalyst particles in an acidic range, in a dispersion liquid to obtain a dispersion system, the pH of which is 2 to 6. [5] The method for producing a photocatalyst coating solution according to any one of [1] to [4], wherein the photocatalyst particles are particles of at least one metal compound selected from the group consisting of titanium oxide, zinc oxide, tungsten oxide, niobium oxide, and tin oxide. [6] The resin includes at least one of a thermoplastic resin and a thermosetting resin; The thermoplastic resin includes at least one of acrylic, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polyamide, polybutylene terephthalate, ABS resin, and acetal resin; The method for producing a photocatalyst coating liquid according to any one of [1] to [5], wherein the thermosetting resin contains at least one of polyurethane, unsaturated polyester, phenolic resin, melamine resin, epoxy resin, and urea resin. [7] The method for producing a photocatalyst coating liquid according to any one of [1] to [6], wherein the inorganic compound having a reactive group contains at least one of a transition element and an element of Groups 12, 13, or 14 of the periodic table. [8] The method for producing a photocatalyst coating solution according to [7], wherein the transition element includes at least one of titanium and zirconium, the Group 12 element of the periodic table includes zinc, the Group 13 element includes aluminum or indium, and the Group 14 element includes silicon or tin. [9] The method for producing a photocatalyst coating liquid according to [8], wherein the inorganic compound having a reactive group is at least one of oxides, hydroxides, oxide hydroxides, oxycarbonates, oxynitrates, hydrochlorides, methoxides, ethoxides, isopropoxides of the transition elements, the Group 12 elements, the Group 13 elements, or the Group 14 elements of the periodic table, and hydrolysis polycondensates of these alkoxides, titanate coupling agents, silane coupling agents, and siloxanes.

[10] The method for producing a photocatalyst coating liquid according to any one of [1] to [9], wherein the solid content of the binder particles is 4% by weight or more based on the total weight of the solid content of the photocatalyst particles and the solid content of the binder particles.

[11] The method for producing a photocatalyst coating solution according to any one of [1] to

[10] , wherein the photocatalyst particles have a volume average particle size of 10 to 500 nm.

[12] The method for producing a photocatalyst coating liquid according to any one of [1] to

[11] , wherein the binder particles have a volume average particle size of 50 to 300 nm.

[13] The method for producing a photocatalyst coating liquid according to any one of [1] to

[12] , wherein the volume average particle diameter of the binder particles is equal to or larger than the volume average particle diameter of the photocatalyst particles.

[14] The method for producing a photocatalyst coating liquid according to any one of [1] to

[13] , wherein the dispersion contains at least one of water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, hypochlorous acid water, acetic acid, lactic acid, formic acid, butyric acid, hydrochloric acid, nitric acid, sulfuric acid, and various organic acids.

[15] The method for producing a photocatalyst coating solution according to any one of [1] to

[14] , wherein the photocatalyst particles have a negative zeta potential in an acidic range, and the binder particles have a positive zeta potential in an acidic range.

[16] The method for producing a photocatalyst coating liquid according to any one of [1] to

[15] , wherein the step of obtaining the dispersion system includes a step of mixing a binder liquid in which the binder particles are dispersed in the dispersion liquid with a photocatalyst slurry in which the photocatalyst particles are dispersed in the dispersion liquid.

[17] The method for producing a photocatalyst coating solution according to any one of [1] to

[16] , wherein the substrate has a negative surface zeta potential. In addition, the invention described in the claims of the original application of this application (Patent Application No. 2023-023196) immediately before the division is appended below. [Appendix 3] [1] A photocatalyst-containing substrate in which a photocatalyst coating liquid is applied onto a substrate, The photocatalyst coating liquid comprises photocatalyst particles having a positive or negative zeta potential in an acidic range, The photocatalyst particle has a core containing a resin, and a shell provided on the surface of the core and containing an inorganic compound having a reactive group. The photocatalyst particle has a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particle in an acidic range. The photocatalyst particle further comprises a dispersion stabilizer. The binder particles are subjected to a polycondensation reaction with the substrate. [2] A photocatalyst-containing substrate in which a photocatalyst coating liquid is applied onto a substrate, The photocatalyst coating liquid includes photocatalyst particles having a positive or negative zeta potential in an acidic range, a core containing a resin, and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, and includes binder particles having a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particles in an acidic range, and has a pH of 2 to 6; The binder particles are subjected to a polycondensation reaction with the substrate. [3] The photocatalyst-attached substrate according to [1] or [2], wherein the reactive group in the shell of the binder particle undergoes a polycondensation reaction with the substrate. [4] The substrate with a photocatalyst according to [3], wherein the substrate undergoes a polycondensation reaction between the reactive group in the shell of the binder particle and the resin in the core. [5] The photocatalyst-attached substrate according to any one of [1] to [4], wherein the substrate is a resin. [6] The substrate with photocatalyst according to any one of [1] to [5], wherein the substrate is at least one of polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, glass, polymethyl methacrylate, cotton thread, and polyethylene nonwoven fabric. [7] The photocatalyst-containing substrate according to any one of [1] to [6], wherein the dispersion stabilizer is at least one of acetylacetone, diacetone alcohol, zirconium acetate, and aluminum acetate. [8] The photocatalyst-containing substrate according to any one of [1] to [7], wherein the dispersion stabilizer is contained in an amount of 0.1 / n mole to 2 / n mole per mole of solid content of the photocatalyst particles, where n is the number of C=O groups. [9] The photocatalyst-attached substrate according to any one of [1] to [8], wherein the photocatalyst particles are particles of at least one metal compound selected from the group consisting of titanium oxide, zinc oxide, tungsten oxide, niobium oxide, and tin oxide.

[10] the resin of the core includes at least one of a thermoplastic resin or a thermosetting resin; The thermoplastic resin includes at least one of acrylic, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polyamide, polybutylene terephthalate, ABS resin, and acetal resin; The photocatalyst-containing substrate according to any one of [1] to [9], wherein the thermosetting resin contains at least one of polyurethane, unsaturated polyester, phenolic resin, melamine resin, epoxy resin, and urea resin.

[11] The photocatalyst-attached substrate according to any one of [1] to

[10] , wherein the inorganic compound having a reactive group contains at least one of a transition element and an element in Groups 12, 13, or 14 of the periodic table.

[12] The transition element includes at least one of titanium and zirconium, the Group 12 element of the periodic table includes zinc, the Group 13 element includes aluminum or indium, and the Group 14 element includes silicon or tin.

[11] The photocatalyst-containing substrate.

[13] The photocatalyst-containing substrate according to

[12] , wherein the inorganic compound having a reactive group is at least one of oxides, hydroxides, oxide hydroxides, oxycarbonates, oxynitrates, hydrochlorides, methoxides, ethoxides, isopropoxides of the transition elements, the Group 12 elements, the Group 13 elements, or the Group 14 elements of the periodic table, and hydrolysis polycondensates of these alkoxides, titanate coupling agents, silane coupling agents, and siloxanes.

[14] The photocatalyst-attached substrate according to any one of [1] to

[13] , wherein the solid content of the binder particles is 4% by weight or more based on the total weight of the solid content of the photocatalyst particles and the solid content of the binder particles.

[15] The photocatalyst-attached substrate according to any one of [1] to

[14] , wherein the photocatalyst particles have a volume average particle size of 10 to 500 nm.

[16] The photocatalyst-attached substrate according to any one of [1] to

[15] , wherein the binder particles have a volume average particle size of 50 to 300 nm.

[17] The photocatalyst-attached substrate according to any one of [1] to

[16] , wherein the volume average particle diameter of the binder particles is equal to or larger than the volume average particle diameter of the photocatalyst particles.

[18] The photocatalyst-containing substrate according to any one of [1] to

[17] , wherein the dispersion contains at least one of water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, hypochlorous acid water, acetic acid, lactic acid, formic acid, butyric acid, hydrochloric acid, nitric acid, sulfuric acid, and various organic acids.

[19] The photocatalyst-containing substrate according to any one of [1] to

[18] , wherein the photocatalyst particles have a negative zeta potential in an acidic range, and the binder particles have a positive zeta potential in an acidic range.

[20] The photocatalyst layer has a high concentration of the binder particles on the surface facing the substrate, and a high concentration of the photocatalyst particles on the surface opposite the surface facing the substrate. [twenty one] The photocatalyst-attached substrate according to any one of [1] to

[20] , wherein the substrate has a negative surface zeta potential. [Explanation of symbols]

[0109] Reference Signs List 1..., 10...binder particle, 11...resin core, 12...inorganic compound shell, 13...polycondensation polymer, 20...photocatalyst particle, 21...dispersion stabilizer, 30...dispersion liquid, 40...photocatalyst coating liquid, 50...coating film, 60...coating film

Claims

1. A photocatalyst-containing substrate in which a photocatalyst coating liquid is applied onto a substrate, The photocatalyst coating liquid includes photocatalyst particles having a positive or negative zeta potential in an acidic range, a core containing a resin, and a shell provided on the surface of the core and containing an inorganic compound having a reactive group, and includes binder particles having a zeta potential of an opposite polarity to the zeta potential of the photocatalyst particles in an acidic range, and has a pH of 2 to 6; the binder particles undergo a polycondensation reaction with the base material; The substrate is at least one of polypropylene, polyethylene terephthalate, polystyrene, glass, polymethyl methacrylate, cotton thread, and polyethylene nonwoven fabric.

2. The photocatalyst-attached substrate according to claim 1 , wherein the reactive group in the shell of the binder particle undergoes a polycondensation reaction with the substrate.

3. The substrate with a photocatalyst according to claim 2 , wherein the substrate undergoes a polycondensation reaction with the reactive group in the shell of the binder particle and the resin in the core.

4. 4. The photocatalyst-attached substrate according to claim 1, wherein the substrate is made of a resin.

5. A substrate with a photocatalyst according to any one of claims 1 to 4, wherein the photocatalyst particles are particles of at least one metal compound selected from the group consisting of titanium oxide, zinc oxide, tungsten oxide, niobium oxide, and tin oxide.

6. the resin of the core includes at least one of a thermoplastic resin or a thermosetting resin; The thermoplastic resin includes at least one of acrylic, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyvinyl alcohol, polycarbonate, polyamide, polybutylene terephthalate, ABS resin, and acetal resin; 6. The photocatalyst-attached substrate according to claim 1, wherein the thermosetting resin contains at least one of polyurethane, unsaturated polyester, phenolic resin, melamine resin, epoxy resin, and urea resin.

7. 7. The photocatalyst-attached substrate according to claim 1, wherein the inorganic compound having a reactive group contains at least one of a transition element and an element of Group 12, 13, or 14 of the periodic table.

8. The transition element includes at least one of titanium and zirconium, the group 12 element of the periodic table includes zinc, the group 13 element includes aluminum or indium, and the group 14 element includes silicon or tin. The photocatalyst-attached substrate according to claim 7.

9. The inorganic compound having a reactive group is at least one of the oxide, hydroxide, oxide hydroxide, oxycarbonate, oxynitrate, hydrochloride, methoxide, ethoxide, isopropoxide, and hydrolysis polycondensation products of these alkoxides, titanate coupling agent, silane coupling agent, and siloxane of the transition element, the group 12 element, the group 13 element, or the group 14 element of the periodic table, the substrate with photocatalyst according to claim 8.

10. 10. The photocatalyst-attached substrate according to claim 1, wherein the solid content of the binder particles is 4% by weight or more based on the total weight of the solid content of the photocatalyst particles and the solid content of the binder particles.

11. 11. The substrate with a photocatalyst according to claim 1, wherein the photocatalyst particles have a volume average particle size of 10 to 500 nm.

12. 12. The substrate with photocatalyst according to claim 1, wherein the binder particles have a volume average particle size of 50 to 300 nm.

13. 13. The substrate with photocatalyst according to claim 1, wherein the volume average particle diameter of the binder particles is equal to or larger than the volume average particle diameter of the photocatalyst particles.

14. The photocatalyst-coated substrate according to any one of claims 1 to 13, further comprising a dispersion liquid, the dispersion liquid containing at least one of water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, hypochlorous acid water, acetic acid, lactic acid, formic acid, butyric acid, hydrochloric acid, nitric acid, sulfuric acid, and various organic acids.

15. 15. The substrate with a photocatalyst according to claim 1, wherein the photocatalyst particles have a negative zeta potential in an acidic range, and the binder particles have a positive zeta potential in an acidic range.

16. The photocatalyst-containing substrate according to any one of claims 1 to 15, comprising a photocatalyst layer formed by applying the photocatalyst coating liquid onto the substrate, the photocatalyst layer having a high concentration of the binder particles on the substrate side surface and a high concentration of the photocatalyst particles on the surface opposite to the substrate side surface.

17. The photocatalyst-attached substrate according to claim 1 , wherein the substrate has a negative surface zeta potential.

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