A photovoltaic self-cleaning nano coating with heat insulation and anti-static functions and a preparation method thereof

Abstract

The application discloses a photovoltaic self-cleaning coating with heat insulation and antistatic functions and a preparation method thereof, and relates to the technical scheme that: nano zinc oxide particles, water and ethanol are mixed to prepare a nano zinc oxide dispersion liquid; a magnesium chloride and ammonium fluoride aqueous solution is added into the nano zinc oxide dispersion liquid, the zinc oxide core is removed after reaction, and a magnesium fluoride emulsion is obtained after purification; antimony trichloride and tin tetrachloride pentahydrate are sequentially added into the acidified magnesium fluoride emulsion, a hollow MgF2@ATO sol is obtained after reaction and purification; tetraethyl orthosilicate is dissolved in the hollow MgF2@ATO sol, and nitric acid aqueous solution is added, stirring is conducted, and aging is carried out to prepare a MgF2@ATO composite sol; an acid hydrolysis mother liquor, the MgF2@ATO composite sol, ethanol, a nitric acid solution and deionized water are mixed, and are coated on a substrate, and a photovoltaic self-cleaning coating is obtained after solidification; the coating can be solidified at room temperature, has low preparation cost, is suitable for industrialized production and application, and the paint film has high light transmittance, hardness, adhesion and antistatic property, and excellent water resistance, weather resistance and heat insulation performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nano-coating, and relates to a photovoltaic self-cleaning nano-coating with heat insulation and anti-static functions and a preparation method thereof. BACKGROUND

[0002] With the rapid development of renewable energy, photovoltaic technology as an important part of it has been widely used. However, in practical application, the surface of photovoltaic panels is easily contaminated by dust, bird droppings and other pollutants, which can reduce the photoelectric conversion efficiency of photovoltaic panels and affect their power generation performance. In addition, photovoltaic panels will continue to heat up under sunlight, and the heat and static electricity generated may affect the stability and life of photovoltaic components, leading to a decline in device performance and even causing safety problems. Therefore, developing a photovoltaic self-cleaning coating with heat insulation and anti-static functions has become a hot research topic.

[0003] In order to reduce the adhesion of dirt and other stains, super-hydrophilic self-cleaning coatings have been widely used. Super-hydrophilic self-cleaning coatings based on nano-silicon dioxide can greatly reduce the adhesion of pollutants due to the nanoscale roughness and super-hydrophilicity of the surface, and have good self-cleaning / easy cleaning effect, but the coating strength and weather resistance are often not satisfactory. Compared with the above, nano-fluorinated magnesium has more excellent mechanical properties and chemical corrosion resistance, and is expected to become an ideal choice for the next generation of hydrophilic self-cleaning coatings.

[0004] In terms of heat insulation and anti-static, patents CN101219859 and CN10250545 have disclosed the feasibility of applying nano-antimony tin oxide (ATO) in the field of heat insulation and anti-static coatings. As an important nano-transparent conductive oxide, it has high transmittance in the visible light region and good shielding ability for infrared light wavelengths in the infrared light region, so it has good heat insulation effect. However, in order to achieve the ideal heat insulation and anti-static effect, the addition amount of ATO often needs to be high, and the occurrence of nano-particle agglomeration will lead to a decrease in the light transmittance of the coating, so it is not suitable for direct application in photovoltaic coatings.

[0005] In summary, although some research has been carried out on anti-fouling self-cleaning and heat insulation and anti-static coatings, there are still challenges in the field of photovoltaics to prepare self-cleaning coatings with good heat insulation, anti-static and anti-reflection properties. SUMMARY

[0006] In order to solve the problems raised in the above background, the first object of the present application is to provide a photovoltaic self-cleaning nano-coating with heat insulation and anti-static functions, which has significant self-cleaning effect, strong water resistance and weather resistance, and good heat insulation and anti-static effect.

[0007] The second object of the present application is to provide a method for preparing the photovoltaic self-cleaning nanocoating with heat insulation and antistatic functions.

[0008] To achieve the above object, the first technical solution of the present application is as follows:

[0009] A photovoltaic self-cleaning nanocoating with heat insulation and antistatic functions and a method for preparing the same, comprising the following steps:

[0010] 1) mixing nano-zinc oxide particles, water and ethanol to prepare a nano-zinc oxide dispersion liquid;

[0011] 2) adding an aqueous solution of magnesium chloride and ammonium fluoride to the zinc oxide dispersion liquid of step 1), reacting at a temperature of 30-75℃ for 0.5-1.5h, then adding cation exchange resin to remove the zinc oxide core, and obtaining a magnesium fluoride emulsion after purification;

[0012] 3) adjusting the magnesium fluoride emulsion to be acidic using 0.5 M hydrochloric acid, sequentially adding SnCl4·5H2O and SbCl3 ethanol solution, refluxing at 60℃ for 6h, and obtaining a hollow MgF2@ATO sol after purification and aging the obtained solution at 100℃ for 48h;

[0013] 4) dissolving tetraethyl orthosilicate in the hollow MgF2@ATO sol, then adding a 10wt%-13wt% mass concentration nitric acid aqueous solution, mixing, stirring and aging to prepare a MgF2@ATO-SiO2 composite sol;

[0014] 5) mixing the acidic hydrolysis mother liquor, the MgF2@ATO-SiO2 composite sol, ethanol, nitric acid solution (15 wt%) and deionized water, coating on a substrate, and obtaining a photovoltaic self-cleaning coating with heat insulation and antistatic functions after solidification;

[0015] The solid content (calculated as SiO2) of the hollow silica sol is 10%-25%.

[0016] Further, the method for preparing the acidic hydrolysis mother liquor is as follows:

[0017] 1) preparing an alcohol-water solution by mixing ethanol and deionized water in a mass ratio of 4:1, and adjusting the pH to 1.5-3.0 using 0.5 M hydrochloric acid to obtain an acidic solution;

[0018] 2) slowly adding tetramethoxysilane to the acidic solution, and stirring at 60℃ for 6h to obtain an acidic hydrolysis mother liquor;

[0019] The solid content (calculated as SiO2) of the acidic hydrolysis mother liquor is 4.5%-10%.

[0020] In some embodiments, the particle size of the nano-ZnO particles is ≤70 nm;

[0021] In some embodiments, the molar ratio of MgCl2 and NH4F is 1.0-5.0:1;

[0022] In some embodiments, the specific reaction temperature is 30-75℃, and the reaction time is 1 hour;

[0023] In some embodiments, the purification method is washing with ethanol and centrifugation at 15000 rpm, and the number of purification is ≥3 times;

[0024] In some embodiments, the pH of the magnesium fluoride emulsion after acidification with 0.5 M hydrochloric acid is 2.0-4.0;

[0025] In some embodiments, the amount of SnCl3 and SnCl4·5H2O powder added is 1:10-1:100 in terms of molar ratio of Sb to Sn;

[0026] In some embodiments, the mass ratio of the acidic hydrolysis mother liquor, hollow MgF2@ATO sol, ethanol, nitric acid solution (15wt%), and deionized water is (10-30):(15-40):(10-60):(1-5):(5-50);

[0027] In some embodiments, the coating method includes any one of blade coating, roller coating, brush coating, spray coating, and spin coating;

[0028] In one embodiment, the substrate includes any one of glass, polycarbonate, TPU, PMMA, PET, aluminum, iron, galvanized steel, stainless steel, and stone;

[0029] In some embodiments, the curing condition is room temperature curing or 10℃-150℃ curing, and the curing time is 10 min-24 h.

[0030] It is worth noting that during the experiment, the inventors found that the coating formed by adding the same amount of ATO to the coating system by blending did not test the obvious antistatic and heat insulation performance. Further increasing the blending amount of ATO, the prepared coating detected a certain antistatic performance, but the heat insulation performance still did not have, and at this time, the coating after curing appeared obvious whitening phenomenon, which seriously affected its light transmittance. This is because the specific surface area of ATO nanoparticles is large, the surface activity is high, and the particles are prone to agglomeration to form agglomerates. If the ATO nano powder is directly dispersed in the base material to prepare a coating, on the one hand, the nano powder cannot be uniformly dispersed in the base material; on the other hand, the agglomerates are difficult to open, the heat insulation performance of the nano powder is poor, and the uniformity, optical and electrical performance of the obtained coating are also greatly affected. Therefore, the hollow MgF2 nano sol is prepared first, then ATO is coated on the surface to form a hollow MgF2@ATO with a double-shell structure, and the prepared MgF2@ATO-SiO2 composite sol is grafted with silica on the surface of ATO, which further reduces the soft agglomeration between ATO, facilitates the dispersion of ATO particles, and makes ATO nanoparticles better realize the heat insulation performance. Because the formed ATO-SiO2 sol and the main components of the glass substrate are the same, a -Si-O-Si- chemical bond can be formed between the surface of the glass, so the adhesion on the glass can be greatly improved.

[0031] Compared with the prior art, the advantages of the present application are:

[0032] 1. Magnesium fluoride has a relatively high refractive index, which can effectively control the propagation and reflection of light in the photovoltaic coating and improve the light absorption efficiency of the photovoltaic device; at the same time, it has low absorption in the ultraviolet to visible light region, so it can transmit sunlight in a wide range, and the preparation of hollow structure is conducive to further reducing the loss of light energy. Compared with the traditional nanosilica coating, the magnesium fluoride nanoparticles also have better chemical stability and low hygroscopicity, which can ensure the use stability of the coating in extreme environment and long-term use.

[0033] 2. ATO is loaded on the surface of hollow magnesium fluoride to prepare hollow MgF2@ATO with a double-shell structure, which can effectively solve the dispersion problem of ATO and make it not appear obvious agglomeration phenomenon under high addition amount condition; on the other hand, the ordered accumulation of hollow nanometer MgF2 particles can promote the uniform and ordered distribution of ATO, reduce the performance instability phenomenon caused by the uneven distribution of ATO in the coating, and effectively improve the heat insulation and antistatic ability of the coating.

[0034] 3.The coating integrates heat insulation, antistatic, antireflection, superhydrophilic and self-cleaning functions, can prevent solid pollutants such as sand, soot and pollen from accumulating on the surface through the micro-nano structure and antistatic function of the surface, and realize self-cleaning function through wind blowing or rainfall; meanwhile, the superhydrophilic property can make rainwater completely spread on the surface to form a water film, block the contact between pollutants and the surface of the coating, and finally remove the surface pollutants through flow to realize self-cleaning function. In addition, the coating has good antireflection and transmittance effect, can effectively improve the transmittance of photovoltaic glass, and can also reduce the temperature of the photovoltaic assembly through heat insulation function, so that the photovoltaic assembly can work at a more suitable temperature, and the power generation efficiency is comprehensively improved.

[0035] 4.The coating provided by the application can be cured at room temperature, and has simple preparation process, low cost, and is suitable for industrialized production and application; and the coating is an inorganic coating, has excellent wear resistance and weather resistance, and has a longer service life, and is very suitable for outdoor use. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A transmission electron microscope (TEM) image of the hollow MgF2@ATO obtained in Example 1.

[0037] Figure 2 A heat insulation test result diagram of the photovoltaic glass, Examples 1-3 and the comparative example.

[0038] Figure 3 A water contact angle result diagram of the photovoltaic glass, Examples 1-3 and the comparative example. DETAILED DESCRIPTION

[0039] The application will be further described below through examples and in conjunction with the drawings. It should be pointed out that the given examples cannot be understood as limiting the protection scope of the application, and some non-essential improvements and adjustments of the application made by the person skilled in the art according to the content of the application should still belong to the protection scope of the application.

[0040] Example 1

[0041] (1) Preparation of nano ZnO dispersion liquid

[0042] 6.0 g of nano ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water, and a high-speed blender was used to uniformly disperse them, and then 58.0 g of anhydrous ethanol was added for dilution, and after stirring for 30 minutes, a nano ZnO dispersion liquid was obtained.

[0043] (2) Preparation of hollow magnesium fluoride

[0044] To the prepared nanometer ZnO dispersion solution of step 1), 8.3 g of 40% mass concentration MgCl2 solution and 4.2 g of 30% mass concentration NH4F solution were added drop by drop in sequence, and then the mixed solution was reacted at 65 ℃ for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times, and then the purified product was redispersed in 50.0 g of water to obtain a hollow magnesium fluoride sol.

[0045] (3) Preparation of MgF2@ATO-SiO2 composite sol

[0046] To the prepared hollow magnesium fluoride sol of step (2), 0.5 M hydrochloric acid was added drop by drop to adjust the pH to 2.0, and heated to 60 ℃ to obtain a hollow magnesium fluoride sol acidic solution. 9.2 g of SnCl4·5H2O was dispersed in 50.0 g of ethanol, 0.5 g of SbCl3 was dispersed in 5.0 g of ethanol, and then the hollow magnesium fluoride sol acidic solution was added in sequence to obtain a mixture solution, and the mixture solution was refluxed at 60 ℃ for 6 h. After cooling to room temperature, the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100 ℃ for 48 h to obtain a hollow MgF2@ATO sol. The transmission electron micrograph of the obtained hollow MgF2@ATO nanoparticles is shown in Figure 1 , it can be seen that the size of the hollow particles is about 40-50 nm, the spherical structure is complete, the cavity structure is obvious, and the wall thickness is uniform;

[0047] 10.2 g of TEOS was dissolved in the above hollow MgF2@ATO sol, and then 10% mass concentration nitric acid aqueous solution was added drop by drop to adjust the pH to 2.0. After stirring for 6 h, the product was aged to obtain a MgF2@ATO-SiO2 composite sol.

[0048] (4) Preparation of coating

[0049] 14.4 g of ethanol and 3.6 g of deionized water were mixed to prepare an alcohol-water mixed solution, and the pH was adjusted to 2.0 with dilute hydrochloric acid, and then 2.0 g of TMOS was added, and stirred for 6 h to obtain an acidic hydrolysis mother liquor. It was placed in a beaker with 25.0 g of MgF2@ATO-SiO2 composite sol, 20.0 g of ethanol, 4.0 g of nitric acid solution (15 wt%), and 50 g of deionized water, and stirred for 10 min to obtain a uniform and translucent coating solution. A small amount of the coating solution was taken with a wool brush and thinly coated on the surface of the photovoltaic glass, and after standing to dry, a second layer was coated, and then it was placed in a 100 ℃ oven for drying for 10 min to completely solidify, to obtain a functional coating.

[0050] Example 2

[0051] (1) Preparation of nano-ZnO dispersion liquid

[0052] 6.0 g of nano-ZnO particles (average particle size 50 nm) were dispersed in 24.0 g of water, and a high-speed blender was used to disperse them uniformly, followed by dilution with 58.0 g of anhydrous ethanol. After stirring for 30 minutes, a nano-ZnO dispersion liquid was obtained.

[0053] (2) Preparation of hollow MgF2

[0054] 9.3 g of a 40% mass concentration MgCl2 solution and 4.0 g of a 30% mass concentration NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at a temperature of 65 °C for 1 hour. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and purification was performed by washing with ethanol and centrifugation at 15000 rpm for 3 times, and the purified product was redispersed in 50.0 g of water to obtain a hollow MgF2 sol.

[0055] (3) Preparation of MgF2@ATO-SiO2 composite sol

[0056] To the hollow MgF2 sol prepared in step (2), 0.5 M hydrochloric acid was added dropwise to adjust the pH to 2.5, and heated to 60 °C to obtain a hollow MgF2 sol acidic solution. 10.0 g of SnCl4·5H2O was dispersed in 50.0 g of ethanol, 0.5 g of SbCl3 was dispersed in 5.0 g of ethanol, and then the hollow MgF2 sol acidic solution was added in sequence to obtain a mixture solution, and the mixture solution was refluxed at 60 °C for 6 hours. After cooling to room temperature, purification was performed by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100 °C for 48 h to obtain a hollow MgF2@ATO sol.

[0057] 10.2 g of TEOS was dissolved in the above hollow MgF2@ATO sol, and a 10% mass concentration nitric acid aqueous solution was added dropwise to adjust the pH to 2.3, and after stirring for 6 h, aging was performed to obtain a MgF2@ATO-SiO2 composite sol.

[0058] (4) Preparation of coating

[0059] An alcohol-water mixed solution was prepared by mixing 16.0 g of ethanol and 4.0 g of deionized water, adjusting the pH to 2.0 with dilute hydrochloric acid, and then adding 2.0 g of TMOS, and stirring for 6 h to obtain an acidic hydrolysis mother liquor. The acidic hydrolysis mother liquor was placed in a beaker with 20.0 g of MgF2@ATO-SiO2 composite sol, 30.0 g of ethanol, 3.5 g of a nitric acid solution (15 wt%), and 40 g of deionized water, and stirred for 10 min to obtain a uniform, translucent coating solution. A small amount of the coating solution was taken up with a wool brush, and thinly coated on the surface of the photovoltaic glass. After standing until it was tack-free, a second layer was applied, and then it was placed in a room temperature drying oven for 24 h to completely cure the functional coating.

[0060] Example 3

[0061] (1) Preparation of a nano-ZnO dispersion

[0062] 4.0 g of nano-ZnO particles (average particle size 60 nm) were dispersed in 18.0 g of water using a high-speed stirrer, and then diluted with 45.0 g of anhydrous ethanol. After stirring for 30 min, a nano-ZnO dispersion was obtained.

[0063] (2) Preparation of hollow magnesium fluoride

[0064] 6.5 g of a 40% mass concentration MgCl2 solution and 3.0 g of a 30% mass concentration NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at a temperature of 65°C for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times, and then redispersed in 50.0 g of water to obtain a hollow magnesium fluoride sol.

[0065] (3) Preparation of a MgF2@ATO-SiO2 composite sol

[0066] To the hollow magnesium fluoride sol prepared in step (2), 0.5 M hydrochloric acid was added dropwise to adjust the pH to 2.0, and heated to 60°C to obtain a hollow magnesium fluoride sol acidic solution. 7.0 g of SnCl4·5H2O was dispersed in 40.0 g of ethanol, and 0.3 g of SbCl3 was dispersed in 5.0 g of ethanol, which were then added in sequence to the hollow magnesium fluoride sol acidic solution to obtain a mixed solution, which was refluxed at 60°C for 6 h. After cooling to room temperature, the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100°C for 48 h to obtain a hollow MgF2@ATO sol.

[0067] 5.0 g TEOS was dissolved in the hollow MgF2@ATO sol above, and 10% nitric acid aqueous solution was added dropwise to adjust pH=2.0. After stirring for 6 h, the MgF2@ATO-SiO2 composite sol was obtained by aging.

[0068] (4) Preparation of coating

[0069] An alcohol-water mixed solution was prepared by mixing 16.0 g ethanol and 4.0 g deionized water, and the pH was adjusted to 2.0 with dilute hydrochloric acid. Then, 4.0 g TMOS was added, and the solution was stirred for 6 h to obtain an acidic hydrolysis mother liquor. The mother liquor was placed in a beaker with 35.0 g MgF2@ATO-SiO2 composite sol, 30.0 g ethanol, 2.5 g nitric acid solution (15 wt%), and 30 g deionized water, and stirred for 10 min to obtain a uniform and translucent coating solution. A small amount of the coating solution was dropped onto the surface of the photovoltaic glass, and a doctor blade was used to coat a layer. After the first layer was dried, a second layer was coated, and then the sample was placed in a 100 ℃ oven for 10 min to completely cure the coating, thereby obtaining a functional coating.

[0070] Example 4

[0071] (1) Preparation of nano-ZnO dispersion

[0072] 6.0 g of nano-ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water using a high-speed blender, and then diluted with 58.0 g of anhydrous ethanol. After stirring for 30 min, a nano-ZnO dispersion was obtained.

[0073] (2) Preparation of hollow magnesium fluoride

[0074] To the nano-ZnO dispersion prepared in step 1), 13.8 g of a 40% MgCl2 solution and 1.5 g of a 30% NH4F solution were added dropwise, and then the mixed solution was reacted at 65 ℃ for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was washed with ethanol and centrifuged at 15000 rpm for 3 times to obtain a hollow magnesium fluoride sol.

[0075] (3) Preparation of MgF2@ATO-SiO2 composite sol

[0076] To the prepared hollow magnesium fluoride sol of step (2), 0.5 M hydrochloric acid was added dropwise to adjust pH = 2.0, and heated to 60°C to obtain a hollow magnesium fluoride sol acidic solution. 9.2 g SnCl4·5H2O was dispersed in 50.0 g ethanol, 0.5 g SbCl3 was dispersed in 5.0 g ethanol, and then added to the hollow magnesium fluoride sol acidic solution in turn to obtain a mixture solution, which was refluxed at 60°C for 6 hours. After cooling to room temperature, purification was carried out by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was re-dispersed in 90.0 g ethanol, and aged at 100°C for 48 h to obtain a hollow MgF2@ATO sol;

[0077] 10.2 g TEOS was dissolved in the above hollow MgF2@ATO sol, and then 10% nitric acid aqueous solution was added dropwise to adjust pH = 2.0. After stirring for 6 h, aging was carried out to obtain a MgF2@ATO-SiO2 composite sol.

[0078] (4) Preparation of coating

[0079] 14.4 g ethanol and 3.6 g deionized water were mixed to prepare an alcohol-water mixed solution, and the pH was adjusted to 2.0 with dilute hydrochloric acid, followed by the addition of 2.0 g TMOS, and stirring for 6 h to obtain an acidic hydrolysis mother liquor. It was placed in a beaker with 25.0 g MgF2@ATO-SiO2 composite sol, 60.0 g ethanol, 1.0 g nitric acid solution (15 wt%), and 5 g deionized water, and stirred for 10 min to obtain a uniform and translucent coating solution. A small amount of coating solution was taken with a wool brush and thinly coated on a stainless steel surface, and after standing until it was tack-free, a second layer was applied, and then it was placed in a 10°C environment for drying for 24 h to completely cure to obtain a functional coating.

[0080] Example 5

[0081] (1) Preparation of nano-ZnO dispersion

[0082] 6.0 g of nano-ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water using a high-speed blender, and then diluted with 58.0 g of anhydrous ethanol, and stirred for 30 min to obtain a nano-ZnO dispersion.

[0083] (2) Preparation of hollow magnesium fluoride

[0084] To the prepared nano-ZnO dispersion solution of step 1), 12.6 g of 40% mass concentration MgCl2 solution and 3.7 g of 30% mass concentration NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at 65 ℃ for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times, and then the purified product was redispersed in 50.0 g of water to obtain a hollow magnesium fluoride sol.

[0085] (3) Preparation of MgF2@ATO-SiO2 composite sol

[0086] To the prepared hollow magnesium fluoride sol of step (2), 0.5 M hydrochloric acid was added dropwise to adjust the pH to 2.0, and heated to 60 ℃ to obtain a hollow magnesium fluoride sol acidic solution. 9.2 g of SnCl4·5H2O was dispersed in 50.0 g of ethanol, 0.1 g of SbCl3 was dispersed in 5.0 g of ethanol, and then the hollow magnesium fluoride sol acidic solution was added in sequence to obtain a mixture solution, and the mixture solution was refluxed at 60 ℃ for 6 h. After cooling to room temperature, the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100 ℃ for 48 h to obtain a hollow MgF2@ATO sol;

[0087] 10.2 g of TEOS was dissolved in the above hollow MgF2@ATO sol, and then 10% mass concentration nitric acid aqueous solution was added dropwise to adjust the pH to 2.0. After stirring for 6 h, the mixture was aged to obtain a MgF2@ATO-SiO2 composite sol.

[0088] (4) Preparation of coating

[0089] 6.4 g of ethanol and 1.6 g of deionized water were mixed to prepare an alcohol-water mixed solution, and the pH was adjusted to 2.0 with dilute hydrochloric acid, and then 2.0 g of TMOS was added, and stirred for 6 h to obtain an acidic hydrolysis mother liquor. It was placed in a beaker with 15.0 g of MgF2@ATO-SiO2 composite sol, 30.0 g of ethanol, 5.0 g of nitric acid solution (15 wt%), and 50 g of deionized water, and stirred for 10 min to obtain a uniform and translucent coating solution. A small amount of coating solution was taken with a wool brush and thinly coated on the surface of a PET film, and after standing to dry, a second layer was coated, and then it was placed in a 50 ℃ oven for drying for 2 h to completely cure to obtain a functional coating.

[0090] Example 6

[0091] (1) Preparation of nano-ZnO dispersion solution

[0092] 6.0 g of nano-ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water, and were uniformly dispersed using a high-speed blender, and then were diluted with 58.0 g of anhydrous ethanol, and after stirring for 30 minutes, a nano-ZnO dispersion was obtained.

[0093] (2) Preparation of hollow magnesium fluoride

[0094] To the nano-ZnO dispersion prepared in step 1), 10.3 g of a 40% mass concentration MgCl2 solution and 4.2 g of a 30% mass concentration NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at 65°C for 1 hour. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and purification was performed by washing with ethanol and centrifugation at 15000 rpm for 3 times, and the purified product was redispersed in 50.0 g of water to obtain a hollow magnesium fluoride sol.

[0095] (3) Preparation of MgF2@ATO-SiO2 composite sol

[0096] To the hollow magnesium fluoride sol prepared in step (2), 0.5 M hydrochloric acid was added dropwise to adjust the pH to 2.0, and was heated to 60°C to obtain a hollow magnesium fluoride sol acidic solution. 9.2 g of SnCl4·5H2O was dispersed in 50.0 g of ethanol, 0.5 g of SbCl3 was dispersed in 5.0 g of ethanol, and then the hollow magnesium fluoride sol acidic solution was added in sequence to obtain a mixture solution, and the mixture solution was refluxed at 60°C for 6 hours. After cooling to room temperature, purification was performed by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and was aged at 100°C for 48 h to obtain a hollow MgF2@ATO sol;

[0097] 10.2 g of TEOS was dissolved in the above hollow MgF2@ATO sol, and then a 10% mass concentration nitric acid aqueous solution was added dropwise to adjust the pH to 2.0, and after stirring for 6 h, aging was performed to obtain a MgF2@ATO-SiO2 composite sol.

[0098] (4) Preparation of coating

[0099] An alcohol-water mixed solution was prepared by mixing 2.4 g of ethanol and 5.6 g of deionized water, adjusting the pH to 2.0 with dilute hydrochloric acid, and then adding 2.0 g of TMOS, and stirring for 6 h to obtain an acidic hydrolysis mother liquor. The acidic hydrolysis mother liquor was placed in a beaker with 25.0 g of MgF2@ATO-SiO2 composite sol, 20.0 g of ethanol, 2.0 g of nitric acid solution (15 wt%), and 20 g of deionized water, and stirred for 10 min to obtain a uniform, translucent coating solution. A small amount of the coating solution was taken up with a wool brush, and thinly coated on the surface of the photovoltaic glass. After standing until it was tack-free, a second layer was applied, and then placed in a 100 ℃ oven to dry for 10 min to completely cure the functional coating.

[0100] Example 7

[0101] (1) Preparation of a nano-ZnO dispersion

[0102] 6.0 g of nano-ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water using a high-speed stirrer, and then diluted with 58.0 g of anhydrous ethanol. After stirring for 30 min, a nano-ZnO dispersion was obtained.

[0103] (2) Preparation of hollow MgF2

[0104] To the nano-ZnO dispersion prepared in step 1), 8.3 g of a 40% mass concentration MgCl2 solution and 4.2 g of a 30% mass concentration NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at 65 ℃ for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times, and then redispersed in 50.0 g of water to obtain a hollow MgF2 sol.

[0105] (3) Preparation of a MgF2@ATO-SiO2 composite sol

[0106] To the hollow MgF2 sol prepared in step (2), 0.5 M hydrochloric acid was added dropwise to adjust the pH to 2.0, and heated to 60 ℃ to obtain a hollow MgF2 sol acidic solution. 9.2 g of SnCl4·5H2O was dispersed in 50.0 g of ethanol, and 0.06 g of SbCl3 was dispersed in 5.0 g of ethanol, which was then added to the hollow MgF2 sol acidic solution to obtain a mixed solution. The mixed solution was refluxed at 60 ℃ for 6 h. After cooling to room temperature, the product was purified by washing with ethanol and centrifugation at 15000 rpm for 3 times. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100 ℃ for 48 h to obtain a hollow MgF2@ATO sol.

[0107] The 10.2 g TEOS was dissolved in the hollow MgF2@ATO sol above, and a 10% mass concentration nitric acid aqueous solution was added dropwise to adjust the pH to 2.0. After stirring for 6 h, the MgF2@ATO-SiO2 composite sol was obtained by aging.

[0108] (4) Preparation of the coating

[0109] An alcohol-water mixed solution was prepared by mixing 14.4 g of ethanol and 3.6 g of deionized water, and the pH was adjusted to 2.0 with dilute hydrochloric acid. Then, 2.0 g of TMOS was added, and the solution was stirred for 6 h to obtain an acidic hydrolysis mother liquor. The acidic hydrolysis mother liquor was placed in a beaker with 40.0 g of the MgF2@ATO-SiO2 composite sol, 20.0 g of ethanol, 3.5 g of a nitric acid solution (15 wt%), and 35.0 g of deionized water, and the mixture was stirred for 10 min to obtain a uniform and translucent coating solution. A small amount of the coating solution was taken with a wool brush and thinly coated on the surface of the photovoltaic glass. After the coating was allowed to air dry, a second layer was coated, and then the coating was placed in a 100 ℃ oven for 10 min to completely dry and solidify, thereby obtaining a functional coating.

[0110] Comparative Example 1

[0111] Comparative Example 1 differs from Example 1 in that the MgF2@ATO-SiO2 composite sol prepared in step (3) was replaced with an ATO sol, and the ATO sol and the hollow magnesium fluoride sol were added to the coating system by blending.

[0112] (1) Preparation of a nano-ZnO dispersion

[0113] 6.0 g of nano-ZnO particles (average particle size 30 nm) were dispersed in 24.0 g of water using a high-speed blender, and then diluted with 58.0 g of an ethanol solution. After stirring for 30 min, a nano-ZnO dispersion was obtained.

[0114] (2) Preparation of hollow magnesium fluoride

[0115] 7.6 g of a 40% MgCl2 solution and 4.6 g of a 30% NH4F solution were added dropwise in sequence, and then the mixed solution was reacted at 65 ℃ for 1 h. After cooling to room temperature, cation exchange resin was added to remove the ZnO core, and the product was purified by washing with ethanol and centrifugation at 15,000 rpm for 3 times. The purified product was redispersed in 50.0 g of water to obtain a hollow magnesium fluoride sol.

[0116] (3) Preparation of an ATO sol

[0117] To 10.0 g of water, 0.5 M hydrochloric acid was added dropwise to adjust pH = 2.0 and heated to 60 °C to obtain an acidic aqueous solution. 9.2 g of SnCl4-5H2O was dispersed in 50.0 g of ethanol, 0.5 g of SbCl3 was dispersed in 5.0 g of ethanol, which were added to the above acidic aqueous solution with stirring, and the mixture solution was refluxed at 60 °C for 6 hours, and then distilled under reduced pressure to about 20.0 g to obtain an ATO sol.

[0118] (4) Preparation of coating layer

[0119] An alcohol-water mixed solution was prepared by mixing 14.4 g of ethanol and 3.6 g of deionized water, and adjusting the pH to 2.0 with dilute hydrochloric acid, and then adding 2.0 g of TMOS, and stirring for 6 h to obtain an acidic hydrolysis mother liquor. It was placed in a beaker with 25.0 g of hollow fluorinated magnesium sol, the ATO sol, 10.0 g of ethanol, 4.0 g of nitric acid solution (15 wt%), and 40 g of deionized water, and after stirring for 10 min, a uniform, translucent coating solution was obtained. A small amount of the coating solution was taken with a wool brush and thinly coated on the surface of the photovoltaic glass, and after standing until it was surface-dried, a second layer was brushed, and then it was placed in a 100 °C oven for 10 min to dry and completely cure to obtain a functional coating layer.

[0120] Comparative Example 2

[0121] Comparative Example 2 differs from Example 1 in that the preparation steps of the hollow fluorinated magnesium in steps (1) and (2) were omitted, and the preparation of the MgF2@ATO-SiO2 composite sol in step (3) was replaced by the preparation of the SiO2@ATO-SiO2 composite sol.

[0122] (1) Preparation of SiO2@ATO-SiO2 composite sol

[0123] 10.0 g of 15 wt% hollow nano-SiO2 aqueous dispersion (average particle size = 50 nm) was dissolved in 40.0 g of water, 0.5 M hydrochloric acid was added dropwise to adjust pH = 2.0 and heated to 60 °C. 9.2 g of SnCl4-5H2O and 0.5 g of SbCl3 were dispersed in 50.0 g and 5.0 g of ethanol, respectively, which were added to the above acidic solution with stirring, and the mixture solution was refluxed at 60 °C for 6 hours. After cooling to room temperature, it was washed with ethanol and centrifuged at 15000 rpm for 3 times for purification. The obtained powder was redispersed in 90.0 g of ethanol, and aged at 100 °C for 48 h to obtain a hollow SiO2@ATO sol;

[0124] 10.2 g TEOS was dissolved in the hollow SiO2@ATO sol above, and a 10% mass concentration nitric acid aqueous solution was added to adjust the pH to 2.0. After stirring for 6 h, the solution was aged to obtain a SiO2@ATO-SiO2 composite sol.

[0125] (2) Preparation of the coating

[0126] An alcohol-water mixed solution was prepared by mixing 14.4 g of ethanol and 3.6 g of deionized water, and the pH was adjusted to 2.0 with dilute hydrochloric acid. Then, 2.0 g of TMOS was added, and the solution was stirred for 6 h to obtain an acidic hydrolysis mother liquor. The solution was placed in a beaker with 25.0 g of SiO2@ATO-SiO2 composite sol, 20.0 g of ethanol, 4.0 g of nitric acid solution (15 wt%), and 50 g of deionized water. After stirring for 10 min, a uniform and translucent coating solution was obtained. A small amount of the coating solution was taken with a wool brush and thinly coated on the surface of the photovoltaic glass. After the first layer was allowed to dry, a second layer was applied, and then the coated glass was placed in a 100 ℃ oven for 10 min to completely cure the coating, thereby obtaining a functional coating.

[0127] Performance test

[0128] The thermal insulation coatings of Examples 1-3 and Comparative Examples 1-2 were tested according to the following test standards, and the specific test results are shown in Table 1 and Table 2. Figures 2-3 ;

[0129] A BTG-6 photovoltaic glass spectral transmittance tester was used to measure the visible light transmittance of the paint film.

[0130] A KREVOR 800 surface resistance tester was used to test the surface resistance of the coating.

[0131] A Buhleng Theta-5000 contact angle meter was used to test the water contact angle of the coating.

[0132] A self-made temperature difference tester was used to test the thermal insulation effect of the thermal insulation coating.

[0133] According to the national standard GB / T 6739-202, the hardness of the coating was tested.

[0134] According to the national standard GB / T 9286-2021, the adhesion of the coating was tested by the crosshatch method.

[0135] According to the national standard GB / T 1733-1993 Method A, the water resistance of the coating was tested.

[0136] According to the national standard GB / T 9274-1988 Method A, the acid resistance of the coating was tested.

[0137] The alkali resistance of the coating was tested according to the national standard GB / T9274-1998 method A.

[0138] Table 1

[0139] Detection index Photovoltaic glass Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Coating appearance - Colorless and transparent Colorless and transparent Colorless and transparent Whitish Colorless and transparent Average light transmittance 91.7% 94.0 93.8 94.2 90.3 93.9 Surface resistance (Ω) 9.17 x 10 11 ]] 9.77 x 10 7 ]] 6.05 x 10 7 ]] 8.26 x 10 7 ]] 7.89 x 10 8 ]] 1.34 x 10 8 ]]> Water contact angle 53.4° 8.3° 9.7° 6.5° 15.2° 7.8° Maximum heat insulation temperature difference 0 11.3 14.6 10.4 2.0 10.7 Pencil hardness - 5H 6H 4H 5H 3H Adhesion - 0 level 0 level 0 level 1 level 0 level Water resistance (10 d) - No blistering and no discoloration No blistering and no discoloration No blistering and no discoloration No blistering and no discoloration No blistering and no discoloration Acid resistance (10% H2SO4, 10d) - No blistering and no discoloration No blistering and no discoloration No blistering and no discoloration No blistering and no discoloration Alkali resistance (20% NaOH, 10 d) No blistering and no discoloration - No blistering and no discoloration No blistering and no discoloration Paint film peeling Paint film peeling ​

[0140] As can be seen from Table 1, in the embodiments of the present application, the coating film not only has good antistatic property and transmittance, but also has excellent thermal insulation property of 14.6 ℃. Further, it is found that the hardness of the coating film is as high as 6H, the adhesion reaches 0 level, and the coating film also has excellent water resistance (no blistering and discoloration of the paint film after 7 days) and weather resistance. The comparative example 1 is to directly add ATO sol to the coating by blending, and it can be seen that the coating appears white, and the antistatic property, thermal insulation property and weather resistance are all poor; compared with the examples 1-3, it can be concluded that the addition of MgF2@ATO-SiO2 composite sol can not only improve the antistatic property, thermal insulation property and hardness of the paint film, but also improve the adhesion of the paint film on the glass. The comparative example 2 is to replace hollow magnesium fluoride with hollow silica, and as can be seen from Table 1, although the antistatic property and thermal insulation property of the comparative example 1 and the example 1 are not much different, the hardness is weakened by 1-2 grades, and the weather resistance is obviously poorer than the example, which shows that the introduction of magnesium fluoride is beneficial to improve the mechanical property and weather resistance of the paint film.

[0141] The technical features of the above-described embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

Claims

1. A method for preparing a photovoltaic self-cleaning coating with thermal insulation and antistatic functions, characterized in that, The method comprises the following steps: 1) mixing nano zinc oxide particles, water and anhydrous ethanol to prepare a nano zinc oxide dispersion; 2) adding an aqueous solution of magnesium chloride and ammonium fluoride to the zinc oxide dispersion of step 1) and reacting at a temperature of 30-75℃ for 0.5-1.5 h, then adding cation exchange resin to remove the zinc oxide core, and obtaining a magnesium fluoride emulsion after purification; 3) adjusting the magnesium fluoride emulsion to be acidic using an acid, and sequentially adding SnCl4·5H2O and SbCl3 ethanol solution, refluxing at 60℃ for 6 h, and aging the obtained solution at 100℃ for 48 h to obtain a hollow MgF2@ATO sol; 4) dissolving tetraethyl orthosilicate in the hollow MgF2@ATO sol, adding an aqueous nitric acid solution, mixing, stirring and aging to prepare a MgF2@ATO-SiO2 composite sol; 5) mixing an acidic hydrolysis mother liquor, the MgF2@ATO-SiO2 composite sol prepared in step 4), ethanol, a nitric acid solution and deionized water, and coating on a substrate to obtain a photovoltaic self-cleaning coating with heat insulation and antistatic functions after solidification. The molar ratio of MgCl2 to NH4F in step 2) is 1.0-5.0:1; The addition amount of SbCl3 and SnCl4·5H2O powder in step 3) is calculated based on Sb and Sn, and the molar ratio of Sb to Sn is 1:10-1:100; The mass ratio of the acidic hydrolysis mother liquor, the hollow MgF2@ATO-SiO2 sol, ethanol, the nitric acid solution and deionized water in step 5) is (10-30):(15-40):(10-60):(1-5):(5-50); The preparation method of the acidic hydrolysis mother liquor is as follows: 1) preparing an alcohol-water solution by mixing ethanol and deionized water at a mass ratio of 4:1, and adjusting the pH to 1.5-3.0 using an acid to obtain an acidic solution; 2) slowly adding tetramethoxysilane to the acidic solution and stirring at 60℃ for 6 h to obtain an acidic hydrolysis mother liquor.

2. The method for preparing a photovoltaic self-cleaning coating with thermal insulation and antistatic functions according to claim 1, characterized in that, The particle size of the nano ZnO particles in step 1) is ≤70 nm.

3. The method according to claim 1, wherein the method is characterized by, The purification method in step 2) is washing with ethanol and centrifugation at 15000 rpm, and the purification times are ≥3.

4. The method according to claim 1, wherein the method is characterized by, The pH of the magnesium fluoride emulsion in step 3) is 2.0-4.

0.

5. The method according to claim 1, wherein the method is characterized by, The concentration of the aqueous nitric acid solution in step 4) is 10-13 wt%; and the concentration of the nitric acid solution in step 5) is 15 wt%.

6. The method for preparing a photovoltaic self-cleaning coating with thermal insulation and antistatic functions according to claim 1 or 2, characterized in that, The acid is 0.5 M hydrochloric acid.

7. The method according to claim 1, wherein the method is characterized by, The coating method in step 5) includes any one of blade coating, roller coating, brush coating, spraying and spin coating; and the substrate includes any one of glass, polycarbonate, TPU, PMMA, PET, aluminum, iron, galvanized steel, stainless steel and stone.

8. The method for preparing a photovoltaic self-cleaning coating with heat insulation and antistatic functions according to claim 1, characterized in that, The solidification conditions are normal temperature solidification or solidification at 10-150℃, and the solidification time is 10 min-24 h.

9. A photovoltaic self-cleaning coating with thermal insulation and antistatic functions, characterized in that, Prepared by the method of any one of claims 1, 2, 3, 4, 5, 7 or 8.

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