Titanium dioxide photocatalytic coating and preparation method and product thereof

Abstract

The present invention relates to a titanium dioxide photocatalytic coating and its preparation method and product. The preparation method comprises the following steps: mixing inorganic particles with a particle size of 1 μm-5 μm with an adhesive, an alkali, and a solvent to obtain a first dispersion; mixing the first dispersion with an inorganic titanium salt solution to obtain a second dispersion; placing the second dispersion on a carrier surface and drying to obtain a semi-cured coating; inverting the carrier carrying the semi-cured coating so that the carrier and the semi-cured coating are in the direction of gravity, and subjecting the semi-cured coating to a hydrothermal reaction in a water vapor environment at a temperature of 160°C-200°C, followed by cooling to obtain a titanium dioxide photocatalytic coating. The titanium dioxide photocatalytic coating obtained by the preparation method has a three-dimensional structure, which is conducive to expanding the reactive surface of the titanium dioxide photocatalytic coating, thereby improving the photocatalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, in particular to a titanium dioxide photocatalytic coating and a preparation method and product thereof. Background Art

[0002] Titanium dioxide (TiO2) is a photocatalytic nanomaterial with high photocatalytic activity. It can utilize the power of light to promote oxidative decomposition reactions. Under the irradiation of light, titanium dioxide remains unchanged but can promote chemical reactions. Titanium dioxide photocatalytic nanomaterials, when exposed to sunlight or indoor fluorescent lighting, can exhibit antibacterial, deodorizing, oil-decomposing, mildew- and algae-resistant, and air-purifying properties. Therefore, they are widely studied and applied in the degradation of organic pollutants.

[0003] However, since titanium dioxide photocatalytic nanomaterials are powdered materials, they usually need to be loaded on a carrier in practical applications. In traditional technology, titanium dioxide photocatalytic nanopowders are usually mixed with a binder to form a colloid, which is then applied to the surface of the carrier, so that the colloid forms a film on the carrier surface to form a photocatalytic coating. However, this surface film formation method often causes the titanium dioxide photocatalytic nanopowders to randomly agglomerate within the film, causing the titanium dioxide photocatalytic nanopowders to lose their large specific surface area characteristics, resulting in a sharp decrease in the overall photocatalytic activity of the coating. Summary of the Invention

[0004] Based on this, it is necessary to provide a titanium dioxide photocatalytic coating and its preparation method and product to address the above problems; the titanium dioxide photocatalytic coating prepared by the preparation method has a three-dimensional structure, which is conducive to expanding the reaction active surface of the titanium dioxide photocatalytic coating, thereby improving the photocatalytic activity.

[0005] A method for preparing a titanium dioxide photocatalytic coating comprises the following steps:

[0006] Mixing inorganic particles with a particle size of 1 μm to 5 μm with a binder, an alkali, and a solvent to obtain a first dispersion;

[0007] mixing the first dispersion liquid with an inorganic titanium salt solution to obtain a second dispersion liquid;

[0008] placing the second dispersion on the surface of the carrier and drying it to obtain a semi-cured coating;

[0009] The carrier carrying the semi-cured coating is inverted so that the carrier and the semi-cured coating are in order in the direction of gravity, and the semi-cured coating is subjected to a hydrothermal reaction in a water vapor environment at a temperature of 160°C-200°C. After the reaction, the titanium dioxide photocatalytic coating is obtained by cooling.

[0010] In one embodiment, in the first dispersion, the mass fraction of the inorganic particles is 0.5%-5%.

[0011] In one embodiment, the inorganic particles are selected from at least one of silicon dioxide, titanium dioxide, zinc oxide, and calcium oxide.

[0012] In one embodiment, in the first dispersion, the mass fraction of the binder is 1%-10%.

[0013] In one embodiment, the adhesive is selected from polyurethane adhesives.

[0014] In one embodiment, in the first dispersion, the mass fraction of the alkali is 0.2%-1%, and the alkali is selected from at least one of sodium hydroxide, potassium hydroxide, and urea.

[0015] In one embodiment, the mass of the inorganic titanium salt solution is 1%-5% of the mass of the second dispersion, and the concentration of the inorganic titanium salt in the inorganic titanium salt solution is 1 mol / L-4 mol / L.

[0016] In one embodiment, the inorganic titanium salt is selected from at least one of titanium chloride and titanium oxysulfate.

[0017] A titanium dioxide photocatalytic coating is prepared by the above-mentioned method for preparing a titanium dioxide photocatalytic coating, wherein nano titanium dioxide particles and inorganic particles are distributed in the titanium dioxide photocatalytic coating.

[0018] A product comprises a carrier and the titanium dioxide photocatalytic coating as described above which is loaded on the surface of the carrier.

[0019] Unlike the traditional hydrothermal method for preparing titanium dioxide, which uses liquid water as the reaction medium, the preparation method described in the present invention uses water vapor to provide the medium required for the reaction of the semi-cured coating. Under temperature conditions of 160°C-200°C, the nano-titanium dioxide particles generated by the crystallization of inorganic titanium salts in the water vapor medium can be more evenly distributed in the titanium dioxide photocatalytic coating, giving the titanium dioxide photocatalytic coating excellent photocatalytic activity. At the same time, water vapor is used to soften the adhesive, allowing the inverted semi-cured coating to be shaped under the gravity of inorganic particles of a specific size, forming a three-dimensional structure with irregular protrusions. The bonding effect of the softened adhesive and the gravity of the inorganic particles of a specific size balance each other, not only ensuring that the titanium dioxide photocatalytic coating forms a three-dimensional structure, but also avoiding problems such as film breakage.

[0020] Therefore, the preparation method described herein, by constructing the titanium dioxide photocatalytic coating into a three-dimensional structure, provides a larger reactive surface compared to conventional titanium dioxide photocatalytic coatings with a single planar configuration, resulting in a titanium dioxide photocatalytic coating with higher overall catalytic activity. Furthermore, this preparation method features a simple process and easily controllable conditions, enabling large-scale industrial production and possessing significant application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope image of the titanium dioxide photocatalytic coating prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] To facilitate understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments or embodiments and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, including any two related listed items, any more related listed items, or the combination of all related listed items.

[0024] The present invention provides a method for preparing a titanium dioxide photocatalytic coating, comprising the following steps:

[0025] S1, mixing inorganic particles with a particle size of 1 μm to 5 μm with a binder, an alkali, and a solvent to obtain a first dispersion;

[0026] S2, mixing the first dispersion liquid with an inorganic titanium salt solution to obtain a second dispersion liquid;

[0027] S3, placing the second dispersion on the surface of the carrier and drying it to obtain a semi-cured coating;

[0028] S4, inverting the carrier carrying the semi-cured coating so that the carrier and the semi-cured coating are in order in the direction of gravity, and allowing the semi-cured coating to undergo a hydrothermal reaction in a water vapor environment at a temperature of 160°C-200°C, and cooling after the reaction to obtain a titanium dioxide photocatalytic coating.

[0029] In step S1, inorganic particles with a particle size of 1μm-5μm are used, which can make the gravity effect of the inorganic particles reach an appropriate range. This not only ensures that the inorganic particles can drive the coating to shape, thereby forming a three-dimensional structure of the titanium dioxide photocatalytic coating, but also avoids the inorganic particles from breaking the film due to excessive gravity.

[0030] Preferably, in the first dispersion, the mass fraction of the inorganic particles is 0.5%-5%, which can make the inorganic particles evenly dispersed in the first dispersion, and thus make the three-dimensional structure formed by the titanium dioxide photocatalytic coating tend to be uniformly distributed, which is beneficial to improving the overall catalytic activity of the titanium dioxide photocatalytic coating.

[0031] Specifically, the inorganic particles include but are not limited to at least one of silicon dioxide, titanium dioxide, zinc oxide, and calcium oxide, and silicon dioxide is more preferred. The silicon dioxide has better compatibility with the nano-titanium dioxide particles generated in the subsequent preparation process.

[0032] Preferably, in the first dispersion, the mass fraction of the binder is 1%-10%. On the one hand, it is conducive to coordinating the gravity of inorganic particles of a specific size to ensure that the titanium dioxide photocatalytic coating forms a three-dimensional structure while avoiding problems such as film breakage; on the other hand, it is conducive to reducing the impact of problems such as polymerization of inorganic particles under the action of the binder, ensuring that the inorganic particles are evenly dispersed in the first dispersion.

[0033] Specifically, the adhesive includes but is not limited to a polyurethane adhesive, more preferably a copolyester polyurethane adhesive or a polyol polyurethane adhesive. The softening effect of the polyurethane adhesive under high-temperature water vapor and the synergistic effect of the gravity of inorganic particles of a specific size are better.

[0034] Preferably, in the first dispersion, the mass fraction of the base is 0.2%-1%, which can provide an alkaline environment for the formation of titanium dioxide, thereby effectively inhibiting hydrolysis and promoting the forward progress of the titanium dioxide formation reaction.

[0035] Specifically, the base is selected from at least one of sodium hydroxide, potassium hydroxide, and urea, and is more preferably sodium hydroxide.

[0036] The solvent is preferably distilled water.

[0037] Preferably, the binder and the base are mixed by adding and mixing them in batches, which is more conducive to uniform dispersion of the components in the first dispersion. More preferably, the binder and the base are added dropwise into the dispersion of the inorganic particles for mixing.

[0038] In one embodiment, inorganic particles with a particle size of 1 μm-5 μm are first dispersed in a solvent, and while stirring and dispersing, a binder and a base are added dropwise. After the addition is completed, mixing is continued for 1 h-4 h to make the inorganic particles and the binder more evenly dispersed in the solvent.

[0039] In step S2, preferably, the mass of the inorganic titanium salt solution is 1%-5% of the mass of the second dispersion, and the concentration of the inorganic titanium salt in the inorganic titanium salt solution is 1 mol / L-4 mol / L, which can enable the inorganic titanium salt to achieve a higher conversion rate in the subsequent hydrothermal reaction process, which is beneficial to improving the photocatalytic performance of the titanium dioxide photocatalytic coating.

[0040] Specifically, the inorganic titanium salt is selected from at least one of titanium chloride and titanyl sulfate, and is more preferably titanium chloride.

[0041] Preferably, the inorganic titanium salt solution is mixed by adding and mixing in batches, and more preferably, the inorganic titanium salt solution is added dropwise into the first dispersion for mixing.

[0042] In one embodiment, the inorganic titanium salt solution is slowly added dropwise to the first dispersion, and after the addition is completed, mixing is continued for 0.5 h to 1 h to make the inorganic titanium salt solution and the first dispersion more uniformly mixed.

[0043] In step S3, the second dispersion is placed on the surface of the carrier and dried to form a semi-cured coating, thereby preventing inorganic particles in the second dispersion from falling off and causing film breakage during the subsequent hydrothermal reaction.

[0044] Preferably, the drying temperature is 35° C.-50° C., and more preferably, the drying time is 1 h-2 h, which is more conducive to the second dispersion forming a stable semi-cured coating.

[0045] It should be noted that the carrier can be an organic material or an inorganic material, and the present invention does not limit this. Those skilled in the art can choose it according to actual preparation requirements. In the present invention, a glass substrate is preferably used as the carrier.

[0046] In step S4, unlike the traditional hydrothermal method for preparing titanium dioxide using liquid water as the reaction medium, in the preparation method described in the present invention, water vapor is used to provide the medium required for the reaction for the semi-cured coating. Under temperature conditions of 160°C-200°C, the nano-titanium dioxide particles generated by the crystallization of inorganic titanium salt in the water vapor medium can be more evenly distributed in the titanium dioxide photocatalytic coating, so that the titanium dioxide photocatalytic coating has excellent photocatalytic activity.

[0047] At the same time, water vapor is used to soften the adhesive, so that the inverted semi-cured coating can be shaped under the gravity of inorganic particles of a specific size, forming a three-dimensional structure with irregular protrusions. The bonding effect of the softened adhesive and the gravity of inorganic particles of a specific size balance each other, which not only ensures that the titanium dioxide photocatalytic coating forms a three-dimensional structure, but also avoids problems such as film breakage.

[0048] It should be noted that since the direction of gravity is always vertically downward, the carrier and the semi-cured coating are in order in the direction of gravity, that is, in the direction of gravity, the carrier is located in the upper layer and the semi-cured layer is located in the lower layer, so that the inverted semi-cured coating can drive the coating to shape under the action of gravity of inorganic particles of a specific size.

[0049] It is further preferred that the hydrothermal reaction time is 12h-48h, which is more conducive to increasing the yield of nano-titanium dioxide and improving the photocatalytic activity of the titanium dioxide photocatalytic coating.

[0050] In one embodiment, a water container can be built into the hydrothermal reaction device, water is added to the water container as a reaction solvent, and the water surface is located at one-tenth to one-fifth of the water container. Then, the surface of the carrier loaded with the semi-cured coating is turned down above the water container, so that the semi-cured coating is opposite to and does not contact the water surface in the water container, and then the semi-cured coating is subjected to a hydrothermal reaction in a water vapor environment at a temperature of 160°C-200°C.

[0051] Therefore, the preparation method described in this invention utilizes inorganic particles of specific sizes and a unique hydrothermal reaction to construct a three-dimensional titanium dioxide photocatalytic coating. This helps expand the reactive surface area of ​​the titanium dioxide photocatalytic coating, thereby enhancing photocatalytic activity. Furthermore, this preparation method features a simple process and easily controllable conditions, enabling large-scale industrial production and possessing significant application potential.

[0052] The present invention provides a titanium dioxide photocatalytic coating prepared by the above-mentioned method for preparing the titanium dioxide photocatalytic coating, wherein nano titanium dioxide particles and inorganic particles are distributed in the titanium dioxide photocatalytic coating.

[0053] The titanium dioxide photocatalytic coating comprises a randomly distributed protrusion structure composed of a portion of nano-titanium dioxide particles and inorganic particles. Compared to conventional titanium dioxide photocatalytic coatings with a single planar configuration, the titanium dioxide photocatalytic coating of the present invention has a larger reactive surface area and, therefore, higher overall catalytic activity. Furthermore, the three-dimensional structure of the titanium dioxide photocatalytic coating provides a good structural foundation for the functionalization of the titanium dioxide photocatalytic coating.

[0054] It should be noted that the crystalline nano-titanium dioxide particles can be distributed on the surface of the inorganic particles, or dispersed in other locations in the titanium dioxide photocatalytic coating, and the present invention does not limit this.

[0055] The present invention also provides a product, comprising a carrier and the titanium dioxide photocatalytic coating as described above loaded on the surface of the carrier.

[0056] The present invention does not impose any restrictions on the choice of carrier, and different carriers can be selected to load the titanium dioxide photocatalytic coating according to the application requirements of different products.

[0057] This product can be used for antibacterial, deodorizing, oil decomposition, mildew and algae prevention, air purification and other aspects, and has a wide range of application value.

[0058] Hereinafter, the titanium dioxide photocatalytic coating and its preparation method and product will be further described through the following specific examples.

[0059] Example 1

[0060] 0.5 parts by weight of silicon dioxide particles with a particle size of about 2 μm were added to 100 parts by weight of distilled water, and 2 parts by weight of copolyester polyurethane adhesive and 0.2 parts by weight of sodium hydroxide were added dropwise while stirring and dispersing. After the addition was completed, stirring was continued for 1 hour to obtain a first dispersion.

[0061] 1 part by weight of a titanium tetrachloride aqueous solution was slowly added dropwise to the first dispersion, and stirred for 0.5 h to obtain a second dispersion, wherein the concentration of titanium tetrachloride in the titanium tetrachloride aqueous solution was 2 mol / L.

[0062] The second dispersion was coated on the surface of the glass substrate and dried at 40° C. for 1 hour to obtain a semi-cured coating.

[0063] A 50ml beaker was placed inside the polytetrafluoroethylene (PTFE)-lined cylinder of a hydrothermal reactor, and 5ml of distilled water was added. A glass substrate bearing the semi-cured coating was then placed horizontally over the beaker, with the surface facing downward, ensuring the semi-cured coating did not contact the water surface. The hydrothermal reactor with the polytetrafluoroethylene (PTFE)-lined cylinder was then placed in an oven and subjected to a hydrothermal reaction at 160°C for 48 hours. After cooling, the glass substrate was removed to obtain a titanium dioxide photocatalytic coating.

[0064] The surface morphology of the prepared titanium dioxide photocatalytic coating was observed using a scanning electron microscope at a magnification of 2000 times. Figure 1As shown, the surface of the titanium dioxide photocatalytic coating has a plurality of randomly distributed protruding structures, and most of the nano-titanium dioxide particles and silicon dioxide particles are distributed in the protruding structures, which proves that the preparation method proposed in the present invention can successfully prepare a titanium dioxide photocatalytic coating with a three-dimensional structure.

[0065] Example 2

[0066] 2 parts by weight of silicon dioxide particles with a particle size of about 5 μm were added to 100 parts by weight of distilled water, and 10 parts by weight of polyurethane adhesive and 0.5 parts by weight of sodium hydroxide were added dropwise while stirring and dispersing. After the addition was completed, stirring was continued for 4 hours to obtain a first dispersion.

[0067] 2 parts by weight of a titanium tetrachloride aqueous solution was slowly added dropwise to the first dispersion, and stirred for 0.5 h to obtain a second dispersion, wherein the concentration of titanium tetrachloride in the titanium tetrachloride aqueous solution was 3 mol / L.

[0068] The second dispersion was coated on the surface of the glass substrate and dried at 40° C. for 1 hour to obtain a semi-cured coating.

[0069] A 50ml beaker was placed inside the polytetrafluoroethylene (PTFE)-lined cylinder of a hydrothermal reactor, and 5ml of distilled water was added. A glass substrate bearing the semi-cured coating was then placed horizontally over the beaker, with the surface facing downward, ensuring the semi-cured coating did not contact the water surface. The hydrothermal reactor with the polytetrafluoroethylene (PTFE)-lined cylinder was then placed in an oven and subjected to a hydrothermal reaction at 180°C for 36 hours. After cooling, the glass substrate was removed to obtain a titanium dioxide photocatalytic coating.

[0070] Example 3

[0071] 4 parts by weight of titanium dioxide particles with a particle size of about 2.5 μm were added to 100 parts by weight of distilled water, and 5 parts by weight of polyurethane adhesive and 0.5 parts by weight of sodium hydroxide were added dropwise while stirring and dispersing. After the addition was completed, stirring was continued for 2 hours to obtain a first dispersion.

[0072] 2 parts by weight of an aqueous solution of titanyl sulfate was slowly added dropwise to the first dispersion, and stirred for 1 hour to obtain a second dispersion, wherein the concentration of titanium tetrachloride in the aqueous solution of titanyl sulfate was 2 mol / L.

[0073] The second dispersion was coated on the surface of the glass substrate and dried at 40° C. for 1 hour to obtain a semi-cured coating.

[0074] A 50ml beaker was placed inside the polytetrafluoroethylene (PTFE)-lined cylinder of a hydrothermal reactor, and 10ml of distilled water was added to the beaker. A glass substrate bearing the semi-cured coating was then placed horizontally over the beaker, with the surface facing downward, ensuring the semi-cured coating did not contact the water surface. The hydrothermal reactor with the polytetrafluoroethylene (PTFE)-lined cylinder was then placed in an oven and subjected to a hydrothermal reaction at 200°C for 20 hours. After cooling, the glass substrate was removed to obtain a titanium dioxide photocatalytic coating.

[0075] Example 4

[0076] 5 parts by weight of silica particles with a particle size of about 1 μm were added to 100 parts by weight of distilled water, and 5 parts by weight of polyol-type polyurethane adhesive and 1 part by weight of sodium hydroxide were added dropwise while stirring and dispersing. After the addition was completed, stirring was continued for 3 hours to obtain a first dispersion.

[0077] 5 parts by weight of a titanium tetrachloride aqueous solution was slowly added dropwise to the first dispersion, and stirred for 1 hour to obtain a second dispersion, wherein the concentration of titanium tetrachloride in the titanium tetrachloride aqueous solution was 2 mol / L.

[0078] The second dispersion was coated on the surface of the glass substrate and dried at 40° C. for 1 hour to obtain a semi-cured coating.

[0079] A 50ml beaker was placed inside the polytetrafluoroethylene (PTFE)-lined cylinder of a hydrothermal reactor, and 10ml of distilled water was added to the beaker. A glass substrate bearing the semi-cured coating was then placed horizontally over the beaker, with the surface facing downward, ensuring the semi-cured coating did not contact the water surface. The hydrothermal reactor with the polytetrafluoroethylene (PTFE)-lined cylinder was then placed in an oven and subjected to a hydrothermal reaction at 180°C for 24 hours. After cooling, the glass substrate was removed to obtain a titanium dioxide photocatalytic coating.

[0080] Comparative Example 1

[0081] 0.5 parts by weight of silicon dioxide particles with a particle size of about 2 μm were added to 100 parts by weight of distilled water, and 2 parts by weight of polyurethane adhesive and 0.2 parts by weight of sodium hydroxide were added dropwise while stirring and dispersing. After the addition was completed, stirring was continued for 1 hour to obtain a first dispersion.

[0082] 1 part by weight of a titanium tetrachloride aqueous solution was slowly added dropwise to the first dispersion, and stirred for 0.5 h to obtain a second dispersion, wherein the concentration of titanium tetrachloride in the titanium tetrachloride aqueous solution was 2 mol / L.

[0083] The second dispersion was coated on the surface of the glass substrate and dried at 40° C. for 1 hour to obtain a semi-cured coating.

[0084] A 50ml beaker was placed inside the polytetrafluoroethylene (PTFE)-lined cylinder of a hydrothermal reactor and filled with distilled water. A glass substrate bearing the semi-cured coating was then placed horizontally over the beaker, with the surface facing downward, so that the semi-cured coating came into contact with the water. The hydrothermal reactor with the polytetrafluoroethylene (PTFE)-lined cylinder was then placed in an oven and subjected to a hydrothermal reaction at 160°C for 48 hours. After cooling, the glass substrate was removed to obtain a titanium dioxide photocatalytic coating.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 1 is that the silicon dioxide particles with a particle size of about 10 μm and an equal mass are used instead of the silicon dioxide particles with a particle size of about 2 μm.

[0087] Comparative Example 3

[0088] The difference between Comparative Example 3 and Example 1 is that silicon dioxide particles with a particle size of about 0.5 μm and an equal mass are used instead of silicon dioxide particles with a particle size of about 2 μm.

[0089] Comparative Example 4

[0090] The difference between Comparative Example 4 and Example 1 is that the hydrothermal reaction is carried out at 120°C.

[0091] Comparative Example 5

[0092] The difference between Comparative Example 5 and Example 1 is that the hydrothermal reaction is carried out at 220°C.

[0093] The performance of Examples 1-4 and Comparative Examples 1-5 was tested. Specifically, the photocatalytic activity was characterized by the classic Rhodamine B solution fading reaction, wherein the initial concentration of the Rhodamine B solution was 5×10 -5 mol / L, after 10 minutes of illumination, the higher the fading rate, the better the photocatalytic activity. The test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As shown in Table 1, the titanium dioxide photocatalytic coatings prepared in Examples 1-4 exhibited excellent photocatalytic activity, with fading rates exceeding 70%. Comparative Example 1, however, employed a conventional hydrothermal method to prepare titanium dioxide. The semi-cured coating was immersed in water upside down. Due to the buoyancy of the water surface, the titanium dioxide photocatalytic coating failed to form a three-dimensional structure. Furthermore, some titanium dioxide generated by the hydrothermal reaction fell into the aqueous solvent, resulting in a loss of catalytic activity in the titanium dioxide photocatalytic coating, resulting in poor photocatalytic activity.

[0097] Comparative Example 2 used silica particles with a particle size of approximately 10 μm. This resulted in film breakage during the hydrothermal reaction due to excessive gravity, resulting in poor photocatalytic activity. Comparative Example 3 used silica particles with a particle size of approximately 0.5 μm. Because the gravity of the silica particles was far less than the adhesive force of the binder softened by high-temperature steam, the titanium dioxide photocatalytic coating failed to form a three-dimensional structure, resulting in lower photocatalytic activity than Examples 1-4.

[0098] In Comparative Example 4, due to the low hydrothermal reaction temperature, insufficient water vapor resulted in low titanium dioxide production, and the binder was not fully softened. As a result, only partial raised structures formed on the surface of the titanium dioxide photocatalytic coating, resulting in poor photocatalytic activity. In Comparative Example 5, due to the high hydrothermal reaction temperature, excessive water vapor temperature and excessive softening of the binder caused the silica particles to break under gravity, resulting in poor photocatalytic activity.

[0099] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a titanium dioxide photocatalytic coating, characterized in that: The steps include: Mixing inorganic particles with a particle size of 1 μm to 5 μm with a binder, an alkali, and a solvent to obtain a first dispersion, wherein the mass fraction of the binder in the first dispersion is 1% to 10%, and the binder is selected from a polyurethane binder; mixing the first dispersion liquid with an inorganic titanium salt solution to obtain a second dispersion liquid; placing the second dispersion on the surface of the carrier and drying it to obtain a semi-cured coating; The carrier carrying the semi-cured coating is inverted so that the carrier and the semi-cured coating are in order in the direction of gravity, and the semi-cured coating is subjected to a hydrothermal reaction in a water vapor environment at a temperature of 160°C-200°C. After the reaction, the titanium dioxide photocatalytic coating is obtained by cooling.

2. The method for preparing a titanium dioxide photocatalytic coating according to claim 1, characterized in that: In the first dispersion, the mass fraction of the inorganic particles is 0.5%-5%.

3. The method for preparing a titanium dioxide photocatalytic coating according to claim 1 or 2, characterized in that: The inorganic particles are selected from at least one of silicon dioxide, titanium dioxide, zinc oxide, and calcium oxide.

4. The method for preparing a titanium dioxide photocatalytic coating according to claim 1, characterized in that: In the first dispersion, the mass fraction of the alkali is 0.2%-1%, and the alkali is selected from at least one of sodium hydroxide, potassium hydroxide, and urea.

5. The method for preparing a titanium dioxide photocatalytic coating according to claim 1, characterized in that: The mass of the inorganic titanium salt solution is 1%-5% of the mass of the second dispersion liquid, and the concentration of the inorganic titanium salt in the inorganic titanium salt solution is 1 mol / L-4 mol / L.

6. The method for preparing a titanium dioxide photocatalytic coating according to claim 5, characterized in that: The inorganic titanium salt is selected from at least one of titanium chloride and titanyl sulfate.

7. A titanium dioxide photocatalytic coating prepared by the method for preparing a titanium dioxide photocatalytic coating according to any one of claims 1 to 6, characterized in that: Nano titanium dioxide particles and inorganic particles are distributed in the titanium dioxide photocatalytic coating.

8. A product, characterized in that It comprises a carrier, and the titanium dioxide photocatalytic coating as claimed in claim 7 which is loaded on the surface of the carrier.

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