Self-cleaning coating for ceramic-based photovoltaic glass and method for its preparation

Abstract

The application discloses a kind of self-cleaning coating for ceramic-based photovoltaic glass and preparation method thereof, and the self-cleaning coating is composed of the following components by mass fraction: 22-25 parts of A nano-silica sol, 3-4 parts of B nano-silica sol, 0.05-0.06 parts of lithium polysilicate, 0.75-0.85 parts of nano-alumina sol, 0.05-0.06 parts of ferric chloride and 200-220 parts of deionized water. The self-cleaning coating formed on the surface of photovoltaic glass based on the coating has good super-hydrophilic performance and self-cleaning performance, and is high in transparency, strong in wear resistance, good in adhesion to the substrate, not easy to fall off from the substrate, and can long-term play good self-cleaning performance. Meanwhile, the coating also has good stability, and still maintains good uniformity after standing still for one week.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of self-cleaning coating for ceramic-based photovoltaic glass, further relate to the preparation method of the above-mentioned self-cleaning coating. BACKGROUND

[0002] Ceramic-based photovoltaic glass self-cleaning coating has wide application in photovoltaic glass surface modification field.However, the current ceramic-based photovoltaic glass self-cleaning coating has the problems of insufficient superhydrophilic and self-cleaning performance, insufficient transparency and poor adhesion to substrate, and is also not wear-resistant, easy to fall off from the surface of substrate, resulting in serious decline of self-cleaning effect, limiting its practical application effect. SUMMARY

[0003] The purpose of the present application is to provide a kind of self-cleaning coating for ceramic-based photovoltaic glass, the self-cleaning coating formed on the surface of photovoltaic glass has good superhydrophilic performance, and high transparency, strong wear resistance, good adhesion to substrate, not easy to fall off from the substrate, can long-term play good self-cleaning performance;The purpose of the present application is to provide the preparation method of the above-mentioned self-cleaning coating.

[0004] Technical scheme: the self-cleaning coating according to the present application is composed of the following components in mass fraction: 22-25 parts of A nano-silica sol, 3-4 parts of B nano-silica sol, 0.05-0.06 parts of lithium polysilicate, 0.75-0.85 parts of nano-alumina sol, 0.05-0.06 parts of ferric chloride and 200-220 parts of deionized water.

[0005] Among them, the solid content of the A nano-silica sol is 15wt.%, the pH value is 3.6-4.5, the average particle size is 3-20 nm, and the particle shape is spherical, lock-shaped, chain-shaped or pearl chain-shaped.

[0006] Among them, the solid content of the B nano-silica sol is 20wt.%, the pH value is 3.6-4.5, the average particle size is 40-80 nm, and the particle shape is spherical, lock-shaped, chain-shaped or pearl chain-shaped.

[0007] Among them, the solid content of the nano-alumina sol is 15wt.%, the pH value is 3.6-4.5, and the average particle size is 18-45 nm.

[0008] The preparation method of the above-mentioned self-cleaning coating is as follows: the formula amount of A nano-silica sol, B nano-silica sol, lithium polysilicate, nano-alumina sol and ferric chloride is added to deionized water, and constant speed stirring is carried out on a magnetic stirrer for more than 24h to obtain a self-cleaning coating.

[0009] Among them, the rotating speed of the constant speed stirring is 1000-2000rmp.

[0010] The application of the self-cleaning coating in the preparation of a ceramic-based photovoltaic glass self-cleaning coating is as follows: the self-cleaning coating is coated on the surface of the photovoltaic glass by spraying, brushing or rolling, and is cured in a vacuum environment for 10-24 hours to obtain a self-cleaning coating on the surface of the photovoltaic glass.

[0011] The curing temperature is 300-400 DEG C.

[0012] Advantages: compared with the prior art, the self-cleaning coating formed on the surface of the photovoltaic glass based on the coating of the application has good superhydrophilic and self-cleaning properties, and has high transparency, strong wear resistance, good adhesion to the substrate, and is not easy to fall off from the substrate, and can long-term play good self-cleaning performance; meanwhile, the coating of the application also has good stability, and still maintains good uniformity after being placed still for one week; the application effectively solves the problems of the existing ceramic-based photovoltaic glass self-cleaning coating, such as insufficient superhydrophilic and self-cleaning performance, insufficient transparency, insufficient adhesion to the substrate, not resistant to wear, easy to fall off from the substrate and cause serious decline of self-cleaning effect. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The flow chart of forming the self-cleaning coating on the surface of the photovoltaic glass;

[0014] Figure 2 The SEM image of forming the self-cleaning coating on the surface of the photovoltaic glass;

[0015] Figure 3 The water contact angle comparison chart of the ceramic-based photovoltaic glass before and after forming the self-cleaning coating of the application;

[0016] Figure 4 The water contact angle comparison chart of the self-cleaning coatings formed by adding iron chloride in the coating and not adding iron chloride;

[0017] Figure 5 The SEM image of the self-cleaning coatings formed by adding iron chloride in the coating and not adding iron chloride; wherein (a) is not adding iron chloride; (b) is adding iron chloride;

[0018] Figure 6 The light transmittance data chart of the ceramic-based photovoltaic glass after forming the self-cleaning coating on the surface of the photovoltaic glass;

[0019] Figure 7 The actual picture of the conventional power generation assembly with the self-cleaning coating; wherein (a) is the front view, and (b) is the side view;

[0020] Figure 8 The power generation amount data chart comparison of the conventional power generation assembly before and after forming the self-cleaning coating. DETAILED DESCRIPTION

[0021] Example 1

[0022] The self-cleaning coating is prepared by the following method: 22 g of pearl chain-shaped nanometer silicon sol with an average particle size of 15 nm and a pH of about 4 (solid content of 15 wt.%) and 3 g of spherical nanometer silicon sol with an average particle size of 45 nm and a pH of about 4 (solid content of 20 wt.%), 0.05 g of lithium polysilicate, 0.75 g of nanometer alumina sol with a pH of about 4 and 0.05 g of ferric chloride are dispersed in 200 mL of deionized water, and stirring is performed on a magnetic stirrer at a rotating speed of 1000 rpm for 24 h to obtain the self-cleaning coating.

[0023] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature, and it is noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm, the air outlet amount of the spray gun is adjusted to achieve the dry spraying effect, the substrate is dry sprayed for several times, and then the substrate is sprayed to be wet by wet spraying to complete the spraying, and the uniformity of the coating on the surface of the substrate should be maintained as much as possible during spraying, and the spraying amount is 20 mL / m 2 ; the self-cleaning coating is cured at 400 ℃ for 20 h in a vacuum environment to obtain a self-cleaning coating on the surface of the photovoltaic glass.

[0024] The scanning electron microscope (SEM) image of the obtained self-cleaning coating is shown in Figure 2 . Figure 2 It is shown that a rough microstructure conducive to hydrophilicity is constructed on the surface of the photovoltaic glass, and the structure is conducive to the realization of superhydrophilicity and self-cleaning performance of the coating.

[0025] The self-cleaning coating is formed on the surface of the photovoltaic glass to realize the surface modification of the photovoltaic glass, a rough microstructure conducive to hydrophilicity is constructed on the surface of the photovoltaic glass, and the chemical composition of the surface of the photovoltaic glass is changed, so that the photovoltaic glass with the self-cleaning coating has good superhydrophilic performance and self-cleaning performance, the water contact angle is <5°, the water contact angle of hexadecane under water is >150°, and the water contact angle comparison chart of the ceramic-based photovoltaic glass before and after the self-cleaning coating is shown in Figure 3 , and it can be seen from Figure 3 that the photovoltaic glass without the self-cleaning coating does not have superhydrophilic performance. The water contact angle comparison chart of the self-cleaning coatings formed by adding ferric chloride in the coating and not adding ferric chloride is shown in Figure 4 , the SEM images of the self-cleaning coatings formed by adding ferric chloride in the coating and not adding ferric chloride are shown in Figure 5 , and it can be seen from Figure 4 and Figure 5 that the Fe2O3 particles formed by adding ferric chloride change the surface morphology of the coating, so that the coating forms a rough microstructure more conducive to hydrophilicity, and thus the water contact angle of the coating is reduced from 20° before adding ferric chloride to 2.6°.

[0026] The self-cleaning coating prepared in Example 1 exhibits good stability, maintaining good uniformity even after standing for a week, which is beneficial for practical production use. Ferric chloride is very stable in the coating system of this invention, generating virtually no hydroxide precipitates. Furthermore, during the curing process, it generates uniformly distributed, low-agglomeration nano-iron oxide particles, which is beneficial for the coating's superhydrophilicity and self-cleaning properties. This is because iron ions have a strong complexing ability with the hydroxyl and silicon-oxygen bonds on lithium polysilicate, while chloride ions can promote the chelation and coordination of metal ions with lithium polysilicate through the hydroxyl and silicon-oxygen bonds (this complexing chemical bond is destroyed during the curing process, so the coating does not contain this bond), forming a soluble complex, thereby effectively reducing the tendency of iron ions to form hydroxide precipitates. In addition, this soluble complex can be uniformly distributed in the coating, enabling the formation of uniformly distributed, low-agglomeration nano-iron oxide particles during curing, which is beneficial for improving the coating's hydrophilicity and self-cleaning properties. However, metal salts such as ferric acetate, ferric sulfate, and copper chloride have a low degree of complexation with lithium polysilicate, which will cause severe hydrolysis in the coating solution, generating a large amount of hydroxide precipitate. This makes it impossible to form a stable and usable coating, and also prevents the formation of uniformly distributed and small-agglomeration nano-iron oxide particles during the curing process. Consequently, the coating cannot obtain excellent superhydrophilic and self-cleaning properties.

[0027] The self-cleaning coating formed on the photovoltaic glass surface based on the self-cleaning coating of Example 1 has good mechanical properties due to the close arrangement of small-sized high-hardness Al2O3, SiO2 and Fe2O3 particles. The coating hardness is as high as 480 (HV) and the adhesion is as high as 5 MPa. After being subjected to 250g load Taber abrasion tester wear for 2000 cycles or 1000g load friction tester 0000# steel wool friction for 150 cycles, it still exhibits good hydrophilic properties, with a water contact angle of less than 10°.

[0028] like Figure 6 As shown, after forming a self-cleaning coating on the surface of photovoltaic glass, the average light transmittance of ceramic-based photovoltaic glass in the wavelength range of 380nm to 1000nm is as high as 91% or more; at the same time, the self-cleaning coating has strong antistatic properties, and the surface impedance value is in the range of ~10. 13 Ω effectively prevents dust from adhering; such as Figure 8 As shown, forming a self-cleaning coating on the surface of photovoltaic glass can increase the average power generation of the power generation module by more than 2.49%.

[0029] Example 2

[0030] The self-cleaning coating is prepared by the following method: 22g of spherical nano-silica sol with an average particle size of 3nm and pH of about 4 (solid content of 15wt.%) and 3g of chain nano-silica sol with an average particle size of 60nm and pH of about 4 (solid content of 20wt.%) are taken; 0.05g of lithium polysilicate, 0.75g of nano-alumina sol with pH of about 4 and 0.05g of iron chloride are dispersed in 200mL of deionized water, and stirring is carried out on a magnetic stirrer at a rotating speed of 1500rpm for 24h to obtain the self-cleaning coating.

[0031] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature, and it is pointed out that the distance between the spray gun and the photovoltaic glass should be kept at 20-30cm, the air output of the spray gun is adjusted to achieve the effect of dry spraying, the substrate is dry sprayed for several times, then the substrate is sprayed to be wet by wet spraying, and the spraying is completed, the uniformity of the coating on the surface of the substrate should be kept as much as possible during spraying, the spraying amount is 20mL / m 2 ; the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 300℃ for 24h in a vacuum environment.

[0032] Example 3

[0033] The self-cleaning coating is prepared by the following method: 22g of spherical nano-silica sol with an average particle size of 3nm and pH of about 4 (solid content of 15wt.%) and 3g of chain nano-silica sol with an average particle size of 60nm and pH of about 4 (solid content of 20wt.%) are taken; 0.05g of lithium polysilicate, 0.75g of nano-alumina sol with pH of about 4 and 0.05g of iron chloride are dispersed in 200mL of deionized water, and stirring is carried out on a magnetic stirrer at a rotating speed of 1500rpm for 24h to obtain the self-cleaning coating.

[0034] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature, and it is pointed out that the distance between the spray gun and the photovoltaic glass should be kept at 20-30cm, the air output of the spray gun is adjusted to achieve the effect of dry spraying, the substrate is dry sprayed for several times, then the substrate is sprayed to be wet by wet spraying, and the spraying is completed, the uniformity of the coating on the surface of the substrate should be kept as much as possible during spraying, the spraying amount is 20mL / m 2 ; the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 300℃ for 24h in a vacuum environment.

[0035] Example 3

[0036] The self-cleaning coating is prepared by the following method: 22 g of a lock-shaped nanometer silicon sol with an average particle size of 9 nm and a pH of about 4 (solid content of 15 wt.%); 3 g of a spherical nanometer silicon sol with an average particle size of 55 nm and a pH of about 4 (solid content of 20 wt.%); 0.05 g of lithium polysilicate, 0.75 g of a nanometer alumina sol with a pH of about 4, and 0.05 g of iron chloride are dispersed in 200 mL of deionized water, and stirred on a magnetic stirrer at a speed of 1000 rpm for 36 h to obtain the self-cleaning coating.

[0037] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature, and it is noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm, the air output of the spray gun is adjusted to be small to achieve dry spraying effect, the substrate is dry sprayed for several times, and then the substrate is sprayed to be wet by wet spraying to complete the spraying, the uniformity of the coating on the surface of the substrate should be kept as much as possible during spraying, and the spraying amount is 20 mL / m 2 ; the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 350 ℃ for 10 h in a vacuum environment.

[0038] Comparative Example 1

[0039] A self-cleaning coating is prepared by the following method: 22 g of a pearl chain-shaped nanometer silicon sol with an average particle size of 15 nm and a pH of about 4 (solid content of 15 wt.%); 3 g of a spherical nanometer silicon sol with an average particle size of 45 nm and a pH of about 4 (solid content of 20 wt.%); 0.05 g of lithium polysilicate, 0.75 g of a nanometer alumina sol with a pH of about 4, and 0.05 g of iron sulfate are dispersed in 200 mL of deionized water, and stirred on a magnetic stirrer at a speed of 1000 rpm for 24 h to obtain the self-cleaning coating.

[0040] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature, and it is noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm, the air output of the spray gun is adjusted to be small to achieve dry spraying effect, the substrate is dry sprayed for several times, and then the substrate is sprayed to be wet by wet spraying to complete the spraying, the uniformity of the coating on the surface of the substrate should be kept as much as possible during spraying, and the spraying amount is 20 mL / m 2 ; the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 400 ℃ for 20 h in a vacuum environment.

[0041] The water contact angle of the coating obtained from Comparative Example 1 is 30°, the coating is not super-hydrophilic, the water-submarine hexadecane contact angle is < 150°, and the coating does not have self-cleaning performance. The water contact angle of the coating is greater than 40° after the coating is subjected to 2000 cycles of Taber abrasion test under a load of 250g or 150 cycles of friction test machine under a load of 1000g. The average light transmittance of the coating at a wavelength of 380nm to 1000nm is less than 90%. This is because the complexing degree of iron ions in the ferric sulfate and lithium polysilicate is low, the tendency of forming water-insoluble hydroxide precipitate is greater than that of ferric chloride, a stable coating cannot be formed, and the nano-iron oxide particles with uniform distribution and small agglomeration degree cannot be generated during the curing process of the coating, and thus the coating cannot have excellent super-hydrophilic performance, self-cleaning performance, wear resistance and transparency. The hardness of the coating is 475 (HV).

[0042] Comparative Example 2

[0043] A self-cleaning coating is prepared by the following method: 22g of pearl chain-shaped nano-silica sol with an average particle size of 15nm and a pH of about 4 (solid content of 15wt.%); 3g of spherical nano-silica sol with an average particle size of 45nm and a pH of about 4 (solid content of 20wt.%); 0.05g of lithium polysilicate, 0.75g of nano-alumina sol with a pH of about 4 and 0.05g of ferric acetate are dispersed in 200mL of deionized water, and the mixture is stirred on a magnetic stirrer at a speed of 1000rpm for 24h to obtain a self-cleaning coating.

[0044] The prepared self-cleaning coating is sprayed on a photovoltaic glass at room temperature. It should be noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30cm, and the air output of the spray gun should be adjusted to achieve dry spraying effect. The substrate is dry sprayed for several times, and then the substrate is wet sprayed until it is wet to complete the spraying. The uniformity of the coating on the surface of the substrate should be maintained as much as possible during the spraying, and the spraying amount is 20mL / m 2 ; and the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing the coating at 400℃ for 20h in a vacuum environment.

[0045] The water contact angle of the coating obtained in Comparative Example 2 is greater than 35°, the coating is not super-hydrophilic, the hexadecane contact angle under water is less than 150°, and the coating does not have self-cleaning performance. After the coating is subjected to 2000 cycles of Taber abrasion test under a load of 250g or 150 cycles of friction test machine 0000# steel wire brush rubbing under a load of 1000g, the water contact angle is greater than 47°. The average light transmittance of the coating in the wavelength range of 380nm to 1000nm is less than 90%. This is because the complexing degree of iron ions in ferric acetate with lithium polysilicate is lower, and the tendency of forming water-insoluble hydroxide precipitate is much greater than that of ferric chloride. Therefore, a stable coating cannot be formed, and the coating cannot generate nano-iron oxide particles with uniform distribution and small agglomeration during the curing process, and thus the coating cannot have excellent super-hydrophilic performance, self-cleaning performance, wear resistance and transparency. The hardness of the coating is 475 (HV).

[0046] Comparative Example 3

[0047] A self-cleaning coating is prepared by the following method: 22g of pearl chain-shaped nano-silica sol with an average particle size of 15nm and a pH of about 4 (solid content of 15wt.%); 3g of spherical nano-silica sol with an average particle size of 45nm and a pH of about 4 (solid content of 20wt.%); 0.05g of sodium polysilicate, 0.75g of nano-alumina sol with a pH of about 4 and 0.05g of ferric chloride are dispersed in 200mL of deionized water, and stirred on a magnetic stirrer at a speed of 1000rpm for 24h to obtain a self-cleaning coating.

[0048] The prepared self-cleaning coating is sprayed on a photovoltaic glass at room temperature. It should be noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30cm, and the air output of the spray gun should be adjusted to achieve dry spraying effect. After several dry spraying passes, the substrate is sprayed to be wet by wet spraying, and the spraying is completed. The uniformity of the coating on the surface of the substrate should be maintained as much as possible during spraying, and the spraying amount is 20mL / m 2 ; and the self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 400℃ for 20h in a vacuum environment.

[0049] The water contact angle of the coating obtained in Comparative Example 3 is 18°, the hexadecane contact angle under water is greater than 150°, and the hardness of the coating is 475 (HV). After the coating is subjected to 2000 cycles of Taber abrasion test under a load of 250g or 150 cycles of friction test machine 0000# steel wire brush rubbing under a load of 1000g, the water contact angle is greater than 35°. This is because the adhesion of sodium polysilicate to the coating is not as good as that of lithium polysilicate in Example 1, so the wear resistance of the coating is not as good as that of Example 1. In addition, the transparency of the obtained coating in a humid environment is low, and the average light transmittance in the wavelength range of 380nm to 1000nm is less than 86%. This is because the stability of sodium polysilicate in a humid environment is not as good as that of lithium polysilicate in Example 1.

[0050] Comparative Example 4

[0051] A self-cleaning coating was prepared by dispersing 22 g of pearl-chain-like nanosilica sol (solid content 15 wt.%) with an average particle size of 15 nm and a pH of about 4, 3 g of spherical nanosilica sol (solid content 20 wt.%) with an average particle size of 45 nm and a pH of about 4, 0.05 g of lithium polysilicate, 0.75 g of nanometer alumina sol with a pH of about 4, and 0.05 g of copper chloride in 200 mL of deionized water, and stirring at a speed of 1000 rpm on a magnetic stirrer for 24 h to obtain the self-cleaning coating.

[0052] The prepared self-cleaning coating was sprayed on a photovoltaic glass at room temperature, and it should be noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm. The air output of the spray gun was adjusted to achieve a dry spraying effect. The substrate was first dry sprayed for several times, and then wet sprayed until the substrate was wet to complete the spraying. The uniformity of the coating on the substrate surface should be maintained as much as possible during spraying. The spraying amount was 20 mL / m 2 . The self-cleaning coating was obtained on the surface of the photovoltaic glass by curing at 400°C for 20 h in a vacuum environment.

[0053] The water contact angle of the coating obtained in Comparative Example 4 was 40°, and the coating was not superhydrophilic. The underwater hexadecane contact angle was <150°, which affected the self-cleaning performance of the coating. The water contact angle of the coating was greater than 55° after the coating was subjected to a Taber abrasion test under a load of 250 g for 2000 cycles or a friction test on a 0000# steel wire felt under a load of 1000 g for 150 cycles. The average light transmittance of the coating in the wavelength range of 380-1000 nm was less than 90%. This was because the complexing degree of copper ions in copper chloride with lithium polysilicate was very low, and the tendency to form a hydroxide precipitate that was insoluble in water was very large. Therefore, a stable coating could not be formed, and the coating could not generate uniformly distributed and small agglomerated nanometer iron oxide particles during the curing process, so that the coating could not obtain excellent superhydrophilic performance, self-cleaning performance, wear resistance, and transparency. The hardness of the coating was 470 (HV).

[0054] Comparative Example 5

[0055] A self-cleaning coating was prepared by dispersing 22 g of pearl-chain-like nanosilica sol (solid content 15 wt.%) with an average particle size of 15 nm and a pH of about 4, 3 g of spherical nanosilica sol (solid content 20 wt.%) with an average particle size of 45 nm and a pH of about 4, 0.05 g of lithium polysilicate, 0.75 g of nanometer alumina sol with a pH of about 4, and 0.1 g of iron chloride in 200 mL of deionized water, and stirring at a speed of 1000 rpm on a magnetic stirrer for 24 h to obtain the self-cleaning coating.

[0056] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature. It is noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm. The air output of the spray gun is adjusted to achieve the effect of dry spraying. The substrate is dry sprayed for several times, and then the substrate is wet sprayed until it is wet, and the spraying is completed. The uniformity of the coating on the surface of the substrate should be maintained as much as possible during spraying. The spraying amount is 20 mL / m 2 The self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 400°C for 20 h in a vacuum environment.

[0057] The water contact angle of the coating obtained in Comparative Example 5 is 12°, which is super-hydrophilic, and the water contact angle of hexadecane under water is >150°. The water contact angle of the coating is greater than 20° after the coating is subjected to 2000 cycles of Taber abrasion test under a load of 250 g or 150 cycles of friction test machine 0000# steel wire brush under a load of 1000 g. The average light transmittance of the coating in the wavelength range of 380-1000 nm is less than 90%, which affects the power generation efficiency. This is because the too high concentration of iron chloride affects the transparency and wear resistance of the coating.

[0058] Comparative Example 6

[0059] A self-cleaning coating is prepared by the following method: 22 g of pearl chain-shaped nanosilica sol with an average particle size of 15 nm and a pH of about 4 (solid content of 15 wt.%); 3 g of spherical nanosilica sol with an average particle size of 45 nm and a pH of about 4 (solid content of 20 wt.%); 0.05 g of lithium polysilicate and 0.05 g of iron chloride are dispersed in 200 mL of deionized water, and stirred on a magnetic stirrer at a speed of 1000 rpm for 24 h to obtain a self-cleaning coating.

[0060] The prepared self-cleaning coating is sprayed on the photovoltaic glass at room temperature. It is noted that the distance between the spray gun and the photovoltaic glass should be kept at 20-30 cm. The air output of the spray gun is adjusted to achieve the effect of dry spraying. The substrate is dry sprayed for several times, and then the substrate is wet sprayed until it is wet, and the spraying is completed. The uniformity of the coating on the surface of the substrate should be maintained as much as possible during spraying. The spraying amount is 20 mL / m 2 The self-cleaning coating is obtained on the surface of the photovoltaic glass by curing at 400°C for 20 h in a vacuum environment.

[0061] The water contact angle of the coating obtained in Comparative Example 6 was 15°, the hardness of the coating was less than 450 (HV), the water contact angle was more than 28° after Taber abrasion test under a load of 250 g for 2000 cycles or a friction test on 0000# steel wire cloth for 150 cycles, the abrasion resistance was poor, and the average light transmittance in the wavelength range of 380 nm to 1000 nm was 85%. This is because the Al2O3 particles in the coating have high hardness, and can reduce the agglomeration of SiO2 particles during the curing of the coating, thereby improving the hardness, abrasion resistance and transparency of the coating.

Claims

1. A self-cleaning coating for ceramic-based photovoltaic glass, characterized in that, The self-cleaning coating is prepared by mixing the following components in the quality parts: 22-25 parts of A nano-silica sol, 3-4 parts of B nano-silica sol, 0.05-0.06 parts of lithium polysilicate, 0.75-0.85 parts of nano-alumina sol, 0.05-0.06 parts of ferric chloride and 200-220 parts of deionized water; the average particle size of the A nano-silica sol is 3-20 nm; the average particle size of the B nano-silica sol is 40-80 nm.

2. Self-cleaning coating for ceramic-based photovoltaic glass according to claim 1, characterized by the fact that: The solid content of the A nano-silica sol is 15-16 wt.%, and the pH value is 3.6-4.

5.

3. Self-cleaning coating for ceramic-based photovoltaic glass according to claim 2, characterized by the fact that: The shape of the nano-particles in the A nano-silica sol is spherical, lock-shaped, chain-shaped or pearl-chain-shaped.

4. The self-cleaning coating for ceramic-based photovoltaic glass according to claim 1, characterized in that: The solid content of the B nano-silica sol is 20-22 wt.%, and the pH value is 3.6-4.

5.

5. Self-cleaning coating for ceramic-based photovoltaic glass according to claim 4, characterized by the fact that: The particle shape of the nano-particles in the B nano-silica sol is spherical, lock-shaped, chain-shaped or pearl-chain-shaped.

6. The self-cleaning coating for ceramic-based photovoltaic glass according to claim 1, characterized in that: The solid content of the nano-alumina sol is 15-16 wt.%, and the pH value is 3.6-4.5; the average particle size is 18-45 nm.

7. The method of producing a self-cleaning coating according to claim 1, characterized in that, Specifically, the formula amount of A nano-silica sol, B nano-silica sol, lithium polysilicate, nano-alumina sol and ferric chloride is added to deionized water, and constant speed stirring is carried out for more than 24 hours in a magnetic stirrer to obtain the self-cleaning coating.

8. The method of claim 7, wherein: The rotating speed of the constant speed stirring is 1000-2000 rmp.

9. Use of the self-cleaning coating according to claim 1 for the production of a self-cleaning coating for ceramic-based photovoltaic glass, characterized by, Specifically, the self-cleaning coating is coated on the surface of photovoltaic glass by spraying, brushing or rolling, and is cured for 10-24 hours in a vacuum environment to obtain a self-cleaning coating on the surface of the photovoltaic glass.

10. Use of the self-cleaning coating according to claim 9 for the preparation of a self-cleaning coating for ceramic-based photovoltaic glass, characterized by: The curing temperature is 300-400℃.

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