Cesium tungsten bronze / titanium dioxide composite coating as well as preparation method and application thereof

Abstract

The invention discloses a cesium tungsten bronze / titanium dioxide composite coating as well as a preparation method and application thereof, and relates to the technical field of functional coating materials. The method comprises the following steps: (1) respectively preparing a cesium tungsten bronze dispersion liquid and a titanium dioxide dispersion liquid by taking water as a solvent; (2) coating a substrate with the cesium tungsten bronze dispersion liquid in a 3D printing manner, and performing first-stage drying at 90-110 DEG C; (3) spraying a titanium dioxide dispersion liquid on the substrate dried in the first stage; and (4) carrying out second-stage drying at 150-300 DEG C to obtain the cesium tungsten bronze / titanium dioxide composite coating. According to the preparation method, water is used as a solvent, no organic solvent is added in the preparation process, the zero-VOC composite coating is prepared, and the coating has excellent photocatalytic self-cleaning performance and near-infrared shielding and heat-insulating performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional coating materials, in particular to a cesium tungsten bronze / titanium dioxide composite coating and a preparation method and application thereof. BACKGROUND

[0002] Glass is widely used in the fields of building, automobile and solar energy due to its transparent property, but its surface is easy to adsorb pollutants such as dust and oil stains, resulting in problems such as reduced light transmittance, reduced aesthetics and increased cleaning cost. To solve these problems, self-cleaning coatings have emerged. Such coatings endow the glass surface with self-cleaning ability by constructing a special microstructure on the glass surface or introducing functional materials (such as photocatalytic materials or low surface energy substances), so as to achieve the goal of manual cleaning or reducing cleaning frequency.

[0003] Titanium dioxide (TiO2) itself is widely used as a self-cleaning material in self-cleaning coatings. However, the catalytic effect is limited when titanium dioxide is used as both a self-cleaning material and a catalyst, resulting in problems such as slow decomposition of organic matter and poor durability. In many coating film-forming materials, organic resins are generally used as film-forming substances, but the use of organic resins can result in poor adhesion and hardness.

[0004] In addition, the existing self-cleaning coating preparation also has VOC emission problems. Chinese patent document CN104725990A discloses a preparation method of a self-cleaning coating based on modified nano-titanium dioxide, which can achieve the purposes of hydrophobicity, oleophobicity, heat insulation and cooling, but this scheme uses a large amount of acetone solvent, defoaming agent, emulsifier, leveling agent, thickening agent and other high VOC substances, which is not conducive to environmental protection. Chinese patent document CN103555010A discloses a visible light responsive self-cleaning coating and a preparation method thereof, which uses ethanol, isopropyl alcohol and acetone as organic solvents, has high VOC content, and the preparation method is complicated, which is not conducive to large-scale promotion. SUMMARY

[0005] One of the purposes of the present application is to provide a preparation method of a cesium tungsten bronze / titanium dioxide composite coating, which uses water as a solvent and does not add organic solvents in the preparation process, thereby preparing a zero-VOC composite coating, and the coating has excellent photocatalytic self-cleaning performance and near-infrared shielding and heat insulation performance.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A preparation method of a cesium tungsten bronze / titanium dioxide composite coating, comprising the following steps:

[0008] (1) preparing cesium tungsten bronze dispersion liquid and titanium dioxide dispersion liquid respectively using water as a solvent;

[0009] (2) The cesium tungsten bronze dispersion liquid is coated on a substrate by 3D printing, and first-stage drying is performed at 90-110°C (for example, 90°C or 100°C or 110°C);

[0010] (3) The titanium dioxide dispersion liquid is sprayed on the substrate dried in the first stage;

[0011] (4) Second-stage drying is performed at 150-300°C (for example, 150°C or 200°C or 300°C) to obtain the cesium tungsten bronze / titanium dioxide composite coating.

[0012] The above method uses water as the solvent, and no organic solvent is added in the preparation process, thereby preparing a zero-VOC composite coating.

[0013] The water as the solvent can be ordinary water, pure water or deionized water.

[0014] In step (2), the first-stage drying time is 20-40 min (for example, 20 min or 30 min or 40 min).

[0015] In step (4), the second-stage drying time is 30-60 min (for example, 30 min or 40 min or 60 min).

[0016] In step (1), the step of preparing the cesium tungsten bronze dispersion liquid includes: uniformly mixing (for example, stirring) cesium tungsten bronze paste, silicon sol or aluminum sol, and solvent (water) in a mass ratio of (30-40):(10-20):(40-50) (preferably (30-40):(15-20):(40-50), for example, 30:20:40 or 40:20:50 or 35:15:45) to obtain a cesium tungsten bronze dispersion liquid with a viscosity of 5-50 cps (preferably 20-50 cps, for example, 20 cps or 32 cps or 50 cps).

[0017] The cesium tungsten bronze paste contains cesium tungsten bronze, the aluminum sol contains aluminum oxide, and the silicon sol contains silicon dioxide.

[0018] In the raw materials for preparing the cesium tungsten bronze dispersion liquid, the cesium tungsten bronze content in the cesium tungsten bronze paste is 15-50% (for example, 15% or 30% or 50%), and the average particle size is ≤50 nm (for example, 31 nm or 40 nm or 50 nm); the aluminum oxide content in the aluminum sol is 10-20% (for example, 15% or 20%), and the average particle size is ≤20 nm (for example, 20 nm); and the silicon dioxide content in the silicon sol is 20-40% (for example, 20%), and the average particle size is ≤20 nm (for example, 20 nm).

[0019] The cesium tungsten bronze in the cesium tungsten bronze slurry is a nanoparticle; the aluminum sol and the silicon sol are both nanoparticle dispersions.

[0020] In step (2), the coating is performed by 3D printing, and the process parameters meet the following conditions: the printing needle caliber is 0.2-0.6mm (for example, 0.2mm or 0.4mm or 0.6mm); the aspect ratio of the dot-shaped structure formed by printing (i.e., the printing dot aspect ratio) is not less than 1.4 (for example, 1.4 or 1.5); and the center distance between adjacent dot-shaped structures (i.e., the protrusion center distance) is 0.5-2.5mm (for example, 0.5mm or 1.5mm or 2.5mm).

[0021] The dot-shaped structure formed by printing can also be understood as a printing dot or a protrusion.

[0022] In step (2), the cesium tungsten bronze dispersion is controlled to form a dot-shaped structure arranged in a hexagonal lattice by 3D printing.

[0023] Specifically, by 3D printing technology, the printing unit is controlled to be arranged in a hexagonal close-packed manner (or hexagonal lattice arrangement), so as to construct a regular micro-nano structure.

[0024] In step (1), the step of configuring the titanium dioxide dispersion includes: mixing the titanium dioxide sol, the silicon sol, and the solvent (water) uniformly (for example, stirring) at a mass ratio of (20-30):(10-20):(50-70) (for example, 30:20:70 or 20:10:50 or 25:15:60) to obtain a titanium dioxide dispersion with a viscosity of 5-40cps (preferably 20-40cps, for example, 20cps or 35cps or 40cps).

[0025] The titanium dioxide sol contains titanium dioxide, and the silicon sol contains silicon dioxide.

[0026] In the raw materials for configuring the titanium dioxide dispersion, the titanium dioxide content in the titanium dioxide sol is 15-25% (for example, 15% or 20% or 25%), and the average particle size is ≤30nm (for example, 16nm or 20nm or 30nm); the silicon dioxide content in the silicon sol is 10-40% (for example, 10% or 20% or 40%), and the average particle size is ≤20nm (for example, 20nm).

[0027] The titanium dioxide in the titanium dioxide sol is a nanoparticle; and the silicon sol is a nanoparticle dispersion.

[0028] In step (3), a spray gun is used for spraying, and the spray gun caliber is 0.8-1.0mm (for example, 0.8mm or 0.9mm or 1.0mm), and the wet film thickness is controlled to be <50um.

[0029] wherein the viscosity unit "cps" can also be expressed as "cp".

[0030] The second object of the present application is to provide a cesium tungsten bronze / titanium dioxide composite coating prepared by the above-mentioned preparation method.

[0031] The third object of the present application is to provide a glass plate having the above-mentioned cesium tungsten bronze / titanium dioxide composite coating on its surface.

[0032] The present application applies nanometer cesium tungsten bronze to self-cleaning coating, and makes full use of its excellent optical performance and photo-thermal conversion performance. After nanometer cesium tungsten bronze is compounded with titanium dioxide, the two produce a synergistic effect in the process of photocatalysis, significantly promoting the decomposition of organic matter. Experiments show that the decomposition rate can be increased by 30%-40%, thereby prolonging the service life of the coating. At the same time, as a photo-thermal conversion material, nanometer cesium tungsten bronze can effectively absorb near-infrared rays, causing the surface temperature of the glass coating to rise by 8-15℃, thereby accelerating the decomposition rate of organic matter. In addition, the nanometer titanium dioxide coating covering the outer layer protects the underlying cesium tungsten bronze, slows down its aging process, and further ensures the long-term stability of the coating. Moreover, the entire preparation process of the self-cleaning coating and its coating of the present application realizes zero VOC emission, and is low in cost, simple in steps, and easy to popularize. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Particle size distribution graph of cesium tungsten bronze slurry with an average particle size of 50 nm;

[0034] Figure 2 Particle size distribution graph of cesium tungsten bronze slurry with an average particle size of 40 nm;

[0035] Figure 3 Particle size distribution graph of cesium tungsten bronze slurry with an average particle size of 31 nm;

[0036] Figure 4 Particle size distribution graph of aluminum sol with an average particle size of 20 nm;

[0037] Figure 5 Particle size distribution graph of silicon sol with an average particle size of 20 nm;

[0038] Figure 6 Particle size distribution graph of titanium dioxide sol with an average particle size of 20 nm;

[0039] Figure 7 Particle size distribution graph of titanium dioxide sol with an average particle size of 30 nm;

[0040] Figure 8 Particle size distribution graph of titanium dioxide sol with an average particle size of 16 nm. DETAILED DESCRIPTION

[0041] The present application prepares a cesium tungsten bronze dispersion liquid and a titanium dioxide dispersion liquid with water as a solvent, does not add an organic solvent in the preparation process, realizes zero VOC emission in the preparation process, and finally obtains a high-efficiency self-cleaning coating with excellent photocatalytic self-cleaning performance and near-infrared shielding and heat insulation performance. Moreover, the present application also introduces cesium tungsten bronze (Cs x WO3) to solve the problems of slow organic matter decomposition speed and poor durability, and introduces nano aluminum sol and silicon sol to solve the problems of poor adhesion and poor hardness. The cesium tungsten bronze is a functional material with unique optical and electrical properties, can produce reactive oxygen species under light conditions, degrade organic pollutants, at the same time, can convert light energy into heat energy, helps the decomposition of pollutants of the self-cleaning coating, and has good chemical stability and thermal stability, is suitable for long-term outdoor use. The silicon sol and the aluminum sol are inorganic sols, have good stability and good bonding force with glass, so as to realize the purposes of high adhesion and high hardness.

[0042] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in combination with examples, and the content mentioned in the examples is not a limitation on the present application. It needs to be explained in advance that the following examples are completed in the laboratory, and those skilled in the art should understand that the amount of each component given in the examples only represents the ratio relationship between the components, and is not a specific limitation.

[0043] Example 1

[0044] Step 1, accurately weigh 30.00 g of cesium tungsten bronze slurry (cesium tungsten bronze content is 50%, average particle size is 50 nm), 20.00 g of aluminum sol (aluminum oxide content is 20%, average particle size is 20 nm), 40.00 g of pure water, mix the three to form a uniform transparent liquid cesium tungsten bronze dispersion liquid, and the viscosity is 20 cps.

[0045] Step 2, place the cesium tungsten bronze dispersion liquid prepared in step 1 in a 3D printer, select a needle with a caliber of 0.2 mm, set the printing point width-height ratio to 1.4, the raised center distance to 0.5 mm, and the printing unit to a hexagonal close arrangement, and print. The printed glass substrate is placed in a 90℃ oven for drying for 40 min to obtain a dried glass substrate.

[0046] Step 3, accurately weigh 30.00 g of titanium dioxide sol (titanium dioxide content is 25%, average particle size is 30 nm); 20.00 g of silicon sol (silicon dioxide content is 10%, average particle size is 20 nm); 70.00 g of water, mix the three to obtain a colorless transparent or slightly milky white titanium dioxide dispersion liquid, and the viscosity is 20 cps.

[0047] Step 4, the titanium dioxide dispersion prepared in step 3 is sprayed on the dry glass substrate prepared in step 2 using a spray gun with a 0.8 mm caliber, and the wet film thickness is controlled to be < 50 um. After spraying, it is placed in a 150°C oven to dry for 60 min, obtaining a self-cleaning coating of nanometer cesium tungsten bronze composite titanium dioxide.

[0048] Example 2

[0049] Step 1, accurately weigh 40.00 g of cesium tungsten bronze slurry (cesium tungsten bronze content is 15%, average particle size is 40 nm), 20.00 g of silica sol (silicon dioxide content is 20%, average particle size is 20 nm), 50.00 g of pure water, and mix them evenly into a uniform transparent liquid cesium tungsten bronze dispersion, with a viscosity of 50 cps.

[0050] Step 2, place the cesium tungsten bronze dispersion prepared in step 1 in a 3D printer, select a needle with a caliber of 0.6 mm, set the printing point width-height ratio to 1.5, the protrusion center distance to 2.5 mm, and the printing unit to a hexagonal close arrangement, and print. The printed glass substrate is placed in a 110°C oven to dry for 20 min, obtaining a dry glass substrate.

[0051] Step 3, accurately weigh 20.00 g of titanium dioxide sol (titanium dioxide content is 15%, average particle size is 20 nm); 10.00 g of silica sol (silicon dioxide content is 40%, average particle size is 20 nm); 50.00 g of water, and mix them evenly to obtain a colorless transparent or slightly milky white titanium dioxide dispersion, with a viscosity of 40 cps.

[0052] Step 4, the titanium dioxide dispersion prepared in step 3 is sprayed on the dry glass substrate prepared in step 2 using a spray gun with a 1.0 mm caliber, and the wet film thickness is controlled to be < 50 um. After spraying, it is placed in a 300°C oven to dry for 30 min, obtaining a self-cleaning coating of nanometer cesium tungsten bronze composite titanium dioxide.

[0053] Example 3

[0054] Step 1, accurately weigh 35.00 g of cesium tungsten bronze slurry (cesium tungsten bronze content is 30%, average particle size is 31 nm), 15.00 g of aluminum sol (aluminum oxide content is 15%, average particle size is 20 nm), 45.00 g of pure water, and mix them evenly into a uniform transparent liquid cesium tungsten bronze dispersion, with a viscosity of 32 cps.

[0055] Step 2, the cesium tungsten bronze dispersion liquid prepared in step 1 is placed in a 3D printer, a needle with a caliber of 0.4 mm is selected, the printing point width-height ratio is set to 1.5, the raised center distance is 1.5 mm, and the printing unit is a hexagonal close arrangement, and printing is performed. The printed glass substrate is placed in a 100°C oven for drying for 30 min to obtain a dried glass substrate.

[0056] Step 3, 25.00 g of titanium dioxide sol (titanium dioxide content is 20%, average particle size is 16 nm), 15.00 g of silica sol (silicon dioxide content is 20%, average particle size is 20 nm), and 60.00 g of water are accurately weighed and mixed uniformly to obtain a colorless transparent or slightly milky white titanium dioxide dispersion liquid with a viscosity of 35 cps.

[0057] Step 4, the titanium dioxide dispersion liquid prepared in step 3 is sprayed on the dried glass substrate prepared in step 2 using a spray gun with a caliber of 0.9 mm, and the wet film thickness is controlled to be <50 um. After spraying, it is placed in a 200°C oven for drying for 40 min to obtain a self-cleaning coating of nano cesium tungsten bronze composite titanium dioxide.

[0058] Comparative Example 1

[0059] Step 1, 15.00 g of aluminum sol (aluminum oxide content is 15%, average particle size is 20 nm) and 45.00 g of pure water are accurately weighed and mixed uniformly to form a uniform transparent liquid aluminum sol dispersion liquid with a viscosity of 35 cps.

[0060] Step 2, the aluminum sol dispersion liquid prepared in step 1 is placed in a 3D printer, a needle with a caliber of 0.4 mm is selected, the printing point width-height ratio is set to 1.5, the raised center distance is 1.5 mm, and the printing unit is a hexagonal close arrangement, and printing is performed. The printed glass substrate is placed in a 100°C oven for drying for 30 min to obtain a dried glass substrate.

[0061] Step 3, 25.00 g of titanium dioxide sol (titanium dioxide content is 20%, average particle size is 16 nm), 15.00 g of silica sol (silicon dioxide content is 20%, average particle size is 20 nm), and 60.00 g of water are accurately weighed and mixed uniformly to obtain a colorless transparent or slightly milky white titanium dioxide dispersion liquid with a viscosity of 32 cps.

[0062] Step 4, the titanium dioxide dispersion liquid prepared in step 3 is sprayed on the dried glass substrate prepared in step 2 using a spray gun with a caliber of 0.9 mm, and the wet film thickness is controlled to be <50 um. After spraying, it is placed in a 200°C oven for drying for 40 min to obtain a self-cleaning coating of nano cesium tungsten bronze composite titanium dioxide.

[0063] The self-cleaning glass coating provided by Examples 1-3 and Comparative Example 1 has the formulation variables shown in Table 1.

[0064] Table 1 Coating formulation of Examples 1-3 and Comparative Example 1

[0065]

[0066] The self-cleaning glass prepared in Examples 1-3 and Comparative Example 1 was tested for light transmittance and organic matter decomposition rate, respectively, and the test results are shown in Table 2. As can be seen from the rhodamine B degradation rate of Examples 1-3 and Comparative Example 1, in Examples 1-3 where cesium tungsten bronze is present, the degradation rate of rhodamine B within two hours can reach 80-90%, while in Comparative Example 1 where no cesium tungsten bronze is present, the degradation rate of rhodamine B is only 50%, indicating that the addition of cesium tungsten bronze can effectively increase the organic matter decomposition rate by 30-40%, thereby improving the cleaning effect of the self-cleaning coating and prolonging the service life. Although the addition of cesium tungsten bronze reduces the visible light transmittance of the glass, the visible light transmittance is still ≥75%, which will not affect the visual life. Due to the synergistic effect of cesium tungsten bronze, the blocking rate of the coating to ultraviolet light also increases from 70% to 92%, and the near-infrared blocking rate increases from 25% to 90%. In this way, not only is the rapid decomposition of organic matter achieved, but also high blocking rates of ultraviolet light and near-infrared light are achieved.

[0067] Table 2 Performance test results of the coating of Examples 1-3 and Comparative Example 1

[0068]

[0069] Note: Simulated sunlight, 2-hour rhodamine B degradation rate.

[0070] The above examples are the preferred implementation of the present application, in addition to this, the present application can be realized in other ways, without departing from the technical solution concept of the present application, any obvious replacement within the protection scope of the present application.

Claims

1. A method for producing a cesium tungsten bronze / titanium dioxide composite coating, characterized by, The method comprises the following steps: (1) preparing a cesium tungsten bronze dispersion liquid and a titanium dioxide dispersion liquid respectively using water as a solvent; (2) coating the cesium tungsten bronze dispersion liquid on a substrate by 3D printing, and performing first-stage drying at 90-110°C; (3) spraying the titanium dioxide dispersion liquid on the substrate dried in the first stage; (4) performing second-stage drying at 150-300°C to obtain a cesium tungsten bronze / titanium dioxide composite coating.

2. The method for preparing cesium tungsten bronze / titania composite coating according to claim 1, characterized in that, In step (1), the step of preparing the cesium tungsten bronze dispersion liquid comprises: Mixing cesium tungsten bronze slurry, silicon sol or aluminum sol, and solvent in a mass ratio of (30-40):(10-20):(40-50) to obtain a cesium tungsten bronze dispersion liquid with a viscosity of 5-50 cps.

3. The method of claim 1, wherein the cesium tungsten bronze / titania composite coating is prepared by a method comprising: In step (1), the step of preparing the titanium dioxide dispersion liquid comprises: Mixing titanium dioxide sol, silicon sol, and solvent in a mass ratio of (20-30):(10-20):(50-70) to obtain a titanium dioxide dispersion liquid with a viscosity of 5-40 cps.

4. The method of claim 1, wherein the cesium tungsten bronze / titania composite coating is prepared by a method comprising: In step (2), the coating is performed by 3D printing, and the process parameters meet the following conditions: The printing needle caliber is 0.2-0.6 mm; The aspect ratio of the dot-shaped structure formed by printing is not less than 1.4; The center distance between adjacent dot-shaped structures is 0.5-2.5 mm.

5. The method of claim 1, wherein the cesium tungsten bronze / titania composite coating is prepared by a method comprising: In step (2), the first-stage drying time is 20-40 min.

6. The method of claim 1, wherein the cesium tungsten bronze / titania composite coating is prepared by a method comprising: In step (3), spraying is performed using a spray gun with a caliber of 0.8-1.0 mm, and the wet film thickness is controlled to be less than 50 um.

7. The method of claim 1, wherein the cesium tungsten bronze / titania composite coating is prepared by a method comprising: In step (4), the second-stage drying time is 30-60 min.

8. A cesium tungsten bronze / titanium dioxide composite coating, characterized by, Prepared by the method of any one of claims 1-7.

9. A glass sheet characterized by, The surface has the cesium tungsten bronze / titanium dioxide composite coating of claim 8.

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