Wear-resistant hydrophobic self-cleaning anti-reflective coating and preparation method thereof

Abstract

The present invention belongs to the field of coating technology, and specifically relates to a wear-resistant, hydrophobic, self-cleaning anti-reflective coating and its preparation method. Using tetraethyl orthosilicate and fluorine-containing silane as silicon sources, an acidic fluorosilicone sol is synthesized using a sol-gel method under acidic conditions. Using tetraethyl orthosilicate as the silicon source, a 50nm SiO2 spherical sol is synthesized under alkaline conditions. After removing ammonia, the sol is mixed with the acidic fluorosilicone sol. A layer of the mixed fluorosilicone sol coating is then coated on a high-borosilicate glass substrate using a dip-coating method. Finally, the coating is cured in a 200°C oven for 1 hour to obtain a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating prepared by the present invention can achieve an average transmittance of 95.57% in the visible light range, a water contact angle of 127°, and a hardness of 7H. After 1000 rubbings with an alcohol cotton ball, the transmittance of the coating does not change significantly. The hydrophobic, self-cleaning anti-reflective coating has high wear resistance, durability, and self-cleaning properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a wear-resistant, hydrophobic, self-cleaning anti-reflective coating and a preparation method thereof. Background Art

[0002] Over the past two decades, the use of photovoltaic methods to convert solar energy into electrical energy has become increasingly common worldwide. Photovoltaic energy systems generate electricity based on the amount of sunlight reaching solar cells. However, since solar panels are used in outdoor environments for long periods of time, the reflection effect of their surfaces and the influence of factors such as dust and dirt in the external environment will reduce the amount of sunlight reaching the solar cells, ultimately leading to a reduction in output power. In order to overcome these problems, it is of great significance to prepare coatings with hydrophobic self-cleaning properties, anti-reflection properties and excellent mechanical properties.

[0003] There are various methods for preparing hydrophobic, self-cleaning anti-reflective coatings, such as template methods, chemical vapor deposition (CVD), spray coating, and sol-gel methods. The sol-gel method is a superior method compared to other methods due to its low process temperature, low cost, high purity, and ability to deposit thin films on substrates of various shapes and sizes. However, hydrophobic, self-cleaning anti-reflective coatings prepared by the sol-gel method have poor mechanical properties, namely poor adhesion to the substrate and poor wear resistance, which limits their large-scale outdoor applications. Therefore, the preparation of hydrophobic, self-cleaning anti-reflective coatings with stable mechanical properties is of great significance in practical applications, and improving the mechanical stability of hydrophobic, self-cleaning anti-reflective coatings is a huge challenge.

[0004] Minzhen Zhong used TEOS and methyltriethoxysilane (MTES) as precursors to prepare hydrophobic SiO2 nanoparticles, which were dispersed in ethanol. Epoxy resin was used as a bonding layer to prepare a two-layer epoxy / silicon dioxide transparent, super-hydrophobic coating with excellent mechanical properties. Although the above method achieved the mechanical stability and hydrophobic self-cleaning properties of the coating, the light transmittance of the coating decreased significantly, and the anti-reflection effect of the coating could not be achieved. Therefore, preparing a coating that takes into account hydrophobic self-cleaning properties, anti-reflection properties, and mechanical properties is a challenging task. Summary of the Invention

[0005] To address the technical problems identified in the background technology section, the present invention provides a wear-resistant, hydrophobic, self-cleaning anti-reflective coating and a preparation method thereof. An acidic fluorosilicone sol and a silica solid sphere sol are prepared by a sol-gel method. After ammonia is removed from the silica solid sphere sol, the two are mixed at different molar ratios of the silica solid sphere sol to the SiO2 in the acidic fluorosilicone sol. The mixture is aged, and the acidic fluorosilicone sol and the silica solid sphere sol are combined to encapsulate and fill the silica solid sphere nanoparticles. A single layer of the coating is then simultaneously deposited on both sides of the glass by a dip-coating method. The coating is then cured in an oven to provide the wear-resistant, hydrophobic, self-cleaning anti-reflective coating.

[0006] The main steps of the preparation method are as follows:

[0007] (1) An acidic fluorosilica sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as solvent, concentrated hydrochloric acid (HCl) as catalyst, tetraethyl orthosilicate (TEOS) and fluorinated silane as silicon sources, and vigorously stirred in a water bath at 30°C for 120 min, followed by aging.

[0008] Among them, Si 总 The molar ratio of (TEOS / FAS-9): EtOH: HCl is 1:33-34:0.63-0.65, the molar ratio of tetraethyl orthosilicate (TEOS) and fluorosilane is 8-10:1-2, and the aging time is 5 days;

[0009] The fluorine-containing silane is nonafluorohexyltriethoxysilane (FAS-9) or perfluorodecyltriethoxysilane (FAS-17).

[0010] Using anhydrous ethanol (EtOH) as solvent, ammonia (NH4OH) as catalyst, and tetraethyl orthosilicate (TEOS) as silicon source, a sol-gel method was used to prepare SiO2 solid ball sol at 25°C with vigorous stirring for 20 minutes and aging for 2 days. The SiO2 solid ball sol was placed in a fume hood with open air and vigorously stirred to remove ammonia. After ammonia removal, the solvent was added until the mass was equal to that before ammonia removal.

[0011] When the molar ratio of TEOS:EtOH:NH4OH is 1-2:38:0.27-1.8, the particle size of the prepared silica solid sphere sol is 20-100 nm.

[0012] (2) a uniform and stable mixed sol is obtained by mixing the silica solid sphere sol with the acidic fluorosilicic sol according to different molar ratios of SiO2;

[0013] The molar ratio of the silicon dioxide solid sphere sol to SiO2 in the acidic fluorosilicic sol is 9:1-6:4.

[0014] (3) The mixed sol was coated onto a glass substrate using a dip-coating method, and then placed in an oven at 200°C for curing for 1 h.

[0015] The pulling speed of the immersion pulling is 1000-1500 μm / s, and the immersion time is 360 s.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The sol-gel method is used to prepare acidic fluorosilicone sol and silica solid sphere sol. The preparation process is simple and easier to apply. In addition, the sol-gel method does not require expensive equipment or high-temperature treatment, and can also produce high-performance and low-cost coatings.

[0018] 2. Use TEOS and fluorinated silane as the silicon source of acidic fluorinated silica sol. The fluorinated groups in fluorinated silane can reduce the surface energy of the coating, laying the foundation for the hydrophobic properties of the coating.

[0019] 3. The silica solid sphere sol and the acidic fluorosilicic sol are mixed according to different molar ratios of SiO2. The spherical nanoparticles of the silica solid spheres provide roughness to the coating. A certain roughness is necessary for a hydrophobic coating. Since there are a large number of hydroxyl groups on the surface of the silica solid spherical nanoparticles, the fluorine-containing side chain groups in the acidic fluorosilicic sol will replace more hydroxyl groups on the surface of the silica solid spherical nanoparticles, thereby expanding the size of the particles. When the fluorine-containing acid sol increases to a certain concentration, the linear chain-like fluorine-containing acid sol fills the space between the silica solid spherical nanoparticles, which can improve the mechanical properties of the coating and increase the wear resistance of the coating.

[0020] 4. A single-layer coating was deposited on both sides of the glass substrate using the dip-coating method. The surface of the coating was smooth and uniform. Experimental results showed that the average light transmittance of the coating could reach 95.57%, and it had anti-reflection properties.

[0021] 5. The coating prepared using the process of the present invention has hydrophobicity, anti-reflection performance and wear resistance. Its average light transmittance can reach 95.57%, the water contact angle is 127°, the hardness of the coating can reach 7H, the dirt on the surface of the coating can be removed, and the self-cleaning effect is good. It has great development prospects in the application of semiconductor devices, optical sensors and solar photovoltaic panels. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a transmission electron microscope image of 50 nm silicon dioxide nanoparticles obtained in Example 3 of the present invention.

[0023] Figure 2 This is a scanning electron microscope cross-sectional image of the coating obtained in Example 3 of the present invention.

[0024] Figure 3 This is a picture of the coating obtained in Example 3 of the present invention observed under a microscope after hardness testing.

[0025] Figure 4 This is a self-cleaning picture of the coating obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the examples, but is not limited thereto.

[0027] Example 1

[0028] (1) Acidic fluorosilica sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as solvent, concentrated hydrochloric acid (HCl) as catalyst, tetraethyl orthosilicate (TEOS) and nonafluorohexyltriethoxysilane (FAS-9) as silicon sources, and aged;

[0029] Among them, Si 总 The molar ratio of (TEOS / FAS-9): EtOH: HCl was 1:33:0.63, the molar ratio of tetraethyl orthosilicate (TEOS) and nonafluorohexyltriethoxysilane (FAS-9) was 10:1, and the aging time was 5 days;

[0030] A 50 nm SiO2 solid sphere sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as solvent, ammonia (NH4OH) as catalyst, and tetraethyl orthosilicate (TEOS) as silicon source. The SiO2 solid sphere sol was placed open in a fume hood and vigorously stirred to remove ammonia. After ammonia removal, the solvent was added until the mass was equal to that before ammonia removal.

[0031] The molar ratio of TEOS:EtOH:NH4OH is 1:38:0.46.

[0032] (2) A 50 nm SiO2 solid sphere sol was mixed with an acidic fluorosilicone sol in a SiO2 molar ratio of 9:1 and aged for 2 days to obtain a uniform and stable mixed sol.

[0033] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 96.05% in the visible light range, a water contact angle of 118°, a hysteresis angle of 15°, and a hardness of 4H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.05%.

[0034] Example 2

[0035] The preparation of acidic fluorosilicic acid sol and SiO2 solid sphere sol is the same as that in Example 1.

[0036] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicone sol were mixed in a SiO2 molar ratio of 8:2 and aged for 2 days to obtain a uniform and stable mixed sol.

[0037] (2) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 95.72% in the visible light range, a water contact angle of 124°, a hysteresis angle of 8°, and a hardness of 6H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 94.13%.

[0038] Example 3

[0039] The preparation of acidic fluorosilicic sol and SiO2 solid sphere sol is the same as that in Example 1.

[0040] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicone sol were mixed in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0041] (2) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 95.57% in the visible light range, a water contact angle of 127°, a hysteresis angle of 4°, and a hardness of 7H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 95.18%.

[0042] Figure 3 The left picture shows no scratches when using a 7H hardness pencil, indicating that the coating hardness can reach 7H. The right picture shows scratches when using an 8H hardness pencil, indicating that the coating hardness does not reach 8H.

[0043] Example 4

[0044] The preparation of acidic fluorosilicic sol and SiO2 solid sphere sol is the same as that in Example 1.

[0045] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicone sol were mixed in a SiO2 molar ratio of 6:4 and aged for 2 days to obtain a uniform and stable mixed sol.

[0046] (2) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 94.50% in the visible light range, a water contact angle of 116°, a hysteresis angle of 15°, and a hardness of 7H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 94.16%.

[0047] Example 5

[0048] (1) Acidic fluorosilica sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as solvent, concentrated hydrochloric acid (HCl) as catalyst, tetraethyl orthosilicate (TEOS) and nonafluorohexyltriethoxysilane (FAS-9) as silicon sources, and aged;

[0049] Among them, Si 总 The molar ratio of (TEOS / FAS-9): EtOH: HCl was 1:34:0.65, the molar ratio of tetraethyl orthosilicate (TEOS) and fluorosilane was 8:2, and the aging time was 5 days;

[0050] (2) A 50 nm SiO2 solid sphere sol was mixed with an acidic fluorosilicone sol in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0051] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 94.31% in the visible light range, a water contact angle of 127°, a hysteresis angle of 4°, and a hardness of 5H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.98%.

[0052] Example 6

[0053] The preparation of acidic fluorosilicic sol and SiO2 solid sphere sol is the same as that in Example 1.

[0054] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicone sol were mixed in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0055] (2) The coating was deposited using a dip-and-pull method with a pull rate of 1500 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h. The coating had an average transmittance of 94.57% in the visible light range, a water contact angle of 127°, a hysteresis angle of 4°, and a hardness of 6H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 93.10%.

[0056] Example 7

[0057] The preparation of acidic fluorosilicic sol is the same as that in Example 1

[0058] (1) Using anhydrous ethanol (EtOH) as solvent, ammonia (NH4OH) as catalyst, and tetraethyl orthosilicate (TEOS) as silicon source, a sol-gel method was used. The mixture was vigorously stirred for 20 min at 25°C and aged for 2 days to prepare a 20 nm SiO2 solid sphere sol. The SiO2 solid sphere sol was placed in a fume hood with open air and vigorously stirred to remove ammonia. After the ammonia was removed, the solvent was added until the mass was equal to that before the ammonia removal.

[0059] The molar ratio of TEOS:EtOH:NH4OH is 2:38:0.27.

[0060] (2) A 20 nm SiO2 solid sphere sol was mixed with an acidic fluorosilicone sol in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0061] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h. The coating had an average transmittance of 93.67% in the visible light range, a water contact angle of 119°, a hysteresis angle of 13°, and a hardness of 6H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 93.00%.

[0062] Example 8

[0063] The preparation of acidic fluorosilicic sol is the same as that in Example 1

[0064] (1) Using anhydrous ethanol (EtOH) as solvent, ammonia (NH4OH) as catalyst, and tetraethyl orthosilicate (TEOS) as silicon source, a sol-gel method was used. The mixture was vigorously stirred for 20 min at 25°C and aged for 2 days to prepare a 100 nm SiO2 solid sphere sol. The SiO2 solid sphere sol was placed in a fume hood with open air and vigorously stirred to remove ammonia. After the ammonia was removed, the solvent was added until the mass was equal to that before the ammonia removal.

[0065] The molar ratio of TEOS:EtOH:NH4OH is 1:38:1.8.

[0066] (2) A 100 nm SiO2 solid sphere sol was mixed with an acidic fluorosilicone sol in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0067] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h. The coating had an average transmittance of 92.21% in the visible light range, a water contact angle of 133°, a hysteresis angle of 3°, and a hardness of 4H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.00%.

[0068] Example 9

[0069] (1) Acidic fluorosilica sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as solvent, concentrated hydrochloric acid (HCl) as catalyst, tetraethyl orthosilicate (TEOS) and perfluorodecyltriethoxysilane (FAS-17) as silicon sources, and aged;

[0070] The molar ratio of Si total (TEOS / FAS-17): EtOH: HCl was 1:34:0.65, and the aging time was 5 days;

[0071] (2) A 50 nm SiO2 solid sphere sol (same as in Example 1) was mixed with an acidic fluorosilica sol (TEOS / FAS-17) at a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0072] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h. The coating had an average transmittance of 93.91% in the visible light range, a water contact angle of 127°, a hysteresis angle of 4°, and a hardness of 5H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.28%.

[0073] Comparative Example 1

[0074] The preparation of acidic fluorosilicic sol and SiO2 solid sphere sol is the same as that in Example 1.

[0075] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicone sol were mixed in a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0076] (2) A coating was sprayed and then cured in an oven at 200°C for 1 hour to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 93.45% in the visible light range, a water contact angle of 127°, a hysteresis angle of 4°, and a hardness of 4H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.00%.

[0077] Comparative Example 2

[0078] (1) Acidic silica sol was prepared by a sol-gel method using anhydrous ethanol (EtOH) as a solvent, concentrated hydrochloric acid (HCl) as a catalyst, and tetraethyl orthosilicate (TEOS) as a silicon source, and then aged;

[0079] The molar ratio of Si:EtOH:HCl was 1:38:0.72, and the aging time was 5 days;

[0080] (2) A 50 nm SiO2 solid sphere sol (same as in Example 1) was mixed with an acidic silica sol at a SiO2 molar ratio of 7:3 and aged for 2 days to obtain a uniform and stable mixed sol.

[0081] (3) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h. The coating had an average transmittance of 94.22% in the visible light range, a water contact angle of 55°, and a hardness of 4H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.00%.

[0082] Comparative Example 3

[0083] The preparation of acidic fluorosilicic acid sol and SiO2 solid sphere sol is the same as that in Example 1.

[0084] (1) A 50 nm SiO2 solid sphere sol and an acidic fluorosilicic acid sol were mixed in a SiO2 molar ratio of 7:3 to obtain a uniform and stable mixed sol.

[0085] (2) The coating was deposited using a dip-and-pull method with a pull rate of 1000 μm / s and an immersion time of 360 s. The coating was then cured in an oven at 200°C for 1 h to produce a wear-resistant, hydrophobic, self-cleaning anti-reflective coating. The coating had an average transmittance of 94.79% in the visible light range, a water contact angle of 93°, a hysteresis angle of 30°, and a hardness of 4H. After 1000 rubbings with an alcohol cotton ball, the average transmittance reached 92.00%.

[0086] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A wear-resistant, hydrophobic, self-cleaning anti-reflective coating, characterized in that: The coating has an average transmittance of 92-97% in the visible light range, a water contact angle of 116-133°, a hysteresis angle of 3-15°, a hardness of 4-8H, and an average transmittance greater than 92% after rubbing with an alcohol cotton ball 1,000 times; The preparation method of the wear-resistant, hydrophobic, self-cleaning anti-reflective coating comprises the following steps: (1) preparing acidic fluorosilicone sol by sol-gel method, aging and setting aside; preparing SiO2 solid sphere sol by sol-gel method; Acidic fluorosilica sol was prepared by sol-gel method using anhydrous ethanol (EtOH) as solvent, concentrated hydrochloric acid (HCl) as catalyst, tetraethyl orthosilicate (TEOS) and fluorinated silane as silicon sources. Si 总 The molar ratio of EtOH:HCl is 1:33-34:0.63-0.65; the molar ratio of tetraethyl orthosilicate and fluorinated silane is 8-10:1-2; the fluorinated silane is nonafluorohexyltriethoxysilane FAS-9 or perfluorodecyltriethoxysilane FAS-17; (2) The SiO2 solid ball sol is placed in a fume hood and stirred vigorously to remove ammonia. After the ammonia is removed, the solvent is added until the mass is equal to that before the ammonia removal. The SiO2 solid ball sol and the acidic fluorosilicone sol are mixed and aged to prepare a stable and uniform mixed sol. (3) The mixed sol obtained in step (2) is plated onto a glass substrate by an immersion-coating method, and then placed in an oven for curing to obtain a wear-resistant, hydrophobic, self-cleaning anti-reflection coating.

2. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 1, wherein: Step (1) uses anhydrous ethanol as solvent, ammonia water as catalyst, and tetraethyl orthosilicate as silicon source to prepare SiO2 solid sphere sol by sol-gel method.

3. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 2, wherein: The molar ratio of TEOS:EtOH:NH4OH is 1-2:38:0.27-1.8, and the particle size of the prepared SiO2 solid sphere sol is 20-100 nm.

4. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 1, wherein: Step (1) Acidic fluorosilicone sol was prepared by vigorous stirring in a water bath at 30° C. for 120 minutes; and the aging time was 5 days.

5. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 1, wherein: Step (1) The SiO2 solid sphere sol was prepared by vigorously stirring at 25°C for 20 minutes and aging for 2 days.

6. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 1, wherein: The molar ratio of SiO2 solid sphere sol to SiO2 in acidic fluorosilicone sol in step (2) is 9:1-6:

4.

7. The wear-resistant, hydrophobic, self-cleaning anti-reflective coating according to claim 1, wherein: In step (3), the pulling speed of the immersion pulling is 1000-1500 μm / s, the immersion time is 360 s, and the material is cured in an oven at 200° C. for 1 h.

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