A superhydrophobic nano - coating and its preparation method

Abstract

The present invention relates to the technical field of coatings, and particularly relates to a superhydrophobic nano-coating and a preparation method thereof. The coating is obtained by spraying a coating liquid on the surface of a substrate and then thermally curing; the coating liquid comprises the following components in parts by weight: 8-12 parts of fluorinated solid microspheres, 3-4 parts of epoxy resin, 0.5-1 part of curing agent, 0.2-0.5 part of trimethylolpropane triglycidyl ether, and 20-30 parts of acetone; the fluorinated solid microspheres are obtained by emulsion polymerization of glycidyl methacrylate, aminated nano-silica, and 4-vinyl aniline. The coating provided by the present invention exhibits superhydrophobic performance and has an extremely low rolling angle.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly to a superhydrophobic nano - coating and a preparation method thereof. Background Art

[0002] In recent years, superhydrophobic materials have become a research hotspot in materials science due to their broad application prospects in fields such as anti - fouling, waterproofing, and self - cleaning. The superhydrophobic phenomenon in nature, such as the lotus leaf effect, has inspired scientists' research on surface roughness and chemical composition. Artificial superhydrophobic coatings have achieved excellent performance with a contact angle exceeding 150° by adjusting surface roughness and chemical properties, and can effectively resist the adhesion of aqueous liquids.

[0003] The preparation of superhydrophobic coatings usually requires a combination of chemical modification and micro - structure design. In current technologies, common preparation methods include sol - gel method, electrochemical deposition method, and spraying technology. By refining the structural design of nanoparticles and introducing chemical functional groups, a surface structure with dual micro - and nano - scale roughness can be constructed, thereby enhancing the superhydrophobic performance.

[0004] Although it is relatively easy to achieve a high contact angle, obtaining a low rolling angle is a more challenging task. The rolling angle is closely related to the roughness uniformity of the coating surface. A high contact angle can usually be achieved through simple chemical modification, but a low rolling angle requires a highly uniform rough structure on the coating surface to ensure that the liquid droplet can roll freely on the surface without staying. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a superhydrophobic nano - coating and a preparation method thereof, so as to provide a superhydrophobic nano - coating with uniform roughness, having an extremely low rolling angle. The extremely low rolling angle helps the liquid droplet to roll and fall off quickly on the coating surface, thereby effectively preventing the liquid from staying on the surface. This characteristic is crucial for keeping the surface clean and dry, especially in application scenarios that require waterproofing and anti - fouling, such as building exterior walls, automobile windshields, and electronic device casings.

[0006] Based on the above purpose, the present invention provides a superhydrophobic nano - coating, which is obtained by spraying a coating liquid on the surface of a substrate and then thermally curing it;

[0007] Further, the coating liquid includes the following components by weight: 8 - 12 parts of fluorinated solid microspheres, 3 - 4 parts of epoxy resin, 0.5 - 1 part of curing agent, 0.2 - 0.5 part of trimethylolpropane triglycidyl ether, and 20 - 30 parts of acetone;

[0008] Further, the preparation steps of the fluorinated solid microspheres are as follows:

[0009] (1) Modify nano-silica with 3-aminopropyltriethoxysilane to obtain amino-functionalized nano-silica;

[0010] (2) Add glycidyl methacrylate, azobisisobutyronitrile, and amino-functionalized nano-silica to 4-vinyl aniline, stir at 30 - 40 °C for 20 - 40 min, then add an emulsifier and stir for 20 - 40 min. Then raise the temperature to 50 - 60 °C, add an aqueous solution of polyvinyl alcohol, stir for 30 - 50 min, raise the temperature to 80 - 90 °C, stir for 5 - 7 h, cool to room temperature, filter, wash, and dry under vacuum to obtain solid microspheres;

[0011] (3) Add the solid microspheres to 1,2-dichloroethane, stir for 20 - 40 min, then add glycidyl ether perfluorononyl ether, stir at 45 - 55 °C for 20 - 40 min, filter, wash, and dry under vacuum to obtain fluorinated solid microspheres.

[0012] Preferably, in the spraying process, the distance between the nozzle and the substrate is 20 - 30 cm, and the spraying pressure is 4 - 5 KPa.

[0013] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0014] Preferably, the curing agent is one or a mixture of diethylenetriamine and triethylenetetramine.

[0015] Preferably, in step (1), the weight ratio of 3-aminopropyltriethoxysilane to nano-silica is 0.05 - 0.2:2.

[0016] Preferably, in step (1), the average particle size of the nano-silica is 20 - 100 nm.

[0017] Preferably, in step (2), the concentration of the aqueous solution of polyvinyl alcohol is 2 wt% - 4 wt%.

[0018] Preferably, in step (2), the emulsifier is a mixture of Span - 80 and Tween - 80 with a weight ratio of 1:9.

[0019] Preferably, in step (2), the weight ratio of glycidyl methacrylate, azobisisobutyronitrile, amino-functionalized nano-silica, 4-vinyl aniline, emulsifier, and aqueous solution of polyvinyl alcohol is 3:0.1:2:10:1:40.

[0020] Preferably, in step (3), the weight ratio of the solid microspheres, 1,2-dichloroethane, and glycidyl ether perfluorononyl ether is 10:80 - 120:0.1 - 1.

[0021] Furthermore, the present invention provides a method for preparing a superhydrophobic nano - coating, and the specific steps are as follows: Add fluorinated solid microspheres, bisphenol A epoxy resin, triethylenetetramine, and glycerol triglycidyl ether into acetone to obtain a coating solution. Then use a spray gun to spray the coating solution onto the surface of a stainless - steel substrate. First, cure it at 55 - 65 °C for 15 - 30 min, and then cure it at 75 - 85 °C for 1.5 - 2.5 h to obtain the superhydrophobic nano - coating.

[0022] Advantages of the present invention:

[0023] The superhydrophobic nano - coating of the present invention achieves remarkable hydrophobic performance through various chemical modifications and structural optimizations. Specifically, it shows a contact angle as high as 159.2° and a rolling angle of only 0.6°. These properties are due to the highly rough structure on the coating surface, which forms an air - cushion effect, effectively capturing air and enhancing the superhydrophobicity of the coating.

[0024] 4 - vinyl aniline adopted in the present invention provides multiple reaction sites: By cross - linking with glycidyl methacrylate, the uniformity of the solid microspheres is enhanced; as the grafting site of glycidyl ether perfluorononyl ether, fluorine chains with low surface energy are introduced; by cross - linking with epoxy resin in the coating matrix, the solid microspheres are evenly distributed on the coating surface. These chemical reactions and physical modifications work together to greatly improve the superhydrophobic performance of the coating.

[0025] The introduced amino - functionalized silica is effectively and evenly dispersed on the surface of the solid microspheres, forming a nano - scale structure, which complements the micron - scale solid microspheres to construct a micro - nano rough surface, further enhancing the superhydrophobic effect of the coating. And the fluorination of the solid microspheres further reduces the surface energy, forming a better low - wettability surface. Detailed implementation mode

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in combination with specific embodiments.

[0027] Example 1:

[0028] (1) Add 2 g of nano - silica with an average particle size of 80 nm into a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.05 g of 3 - aminopropyltriethoxysilane, stir at 45 °C for 6 h, centrifuge, wash with deionized water 3 times and with absolute ethanol 3 times, and dry under vacuum to obtain amino - functionalized nano - silica;

[0029] (2) Add 1 g of glycidyl methacrylate, 0.05 g of azobisisobutyronitrile, and 1 g of amino-functionalized nano-silica into 10 g of 4-vinyl aniline, stir for 20 min at 30 °C, then add 0.05 g of Span-80 and 0.45 g of Tween-80, stir for 20 min, then raise the temperature to 50 °C, add 30 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 30 min, raise the temperature to 80 °C, stir for 5 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry under vacuum to obtain solid microspheres;

[0030] (3) Add 10 g of solid microspheres into 80 g of 1,2-dichloroethane, stir for 20 min, then add 0.1 g of glycidyl ether perfluorononyl ether, stir for 20 min at 45 °C, filter, wash with absolute ethanol 3 times, and dry under vacuum to obtain fluorinated solid microspheres;

[0031] (4) Add 8 g of fluorinated solid microspheres, 3 g of bisphenol A epoxy resin, 0.5 g of diethylenetriamine, and 0.2 g of trimethylolpropane triglycidyl ether into 20 g of acetone to obtain a coating solution, then use a spray gun to spray the coating solution onto the surface of a stainless steel substrate, with the nozzle 20 cm away from the substrate and the spraying pressure of 4 KPa, cure at 60 °C for 20 min first, and then cure at 80 °C for 2 h to obtain a superhydrophobic nano-coating.

[0032] Example 2:

[0033] (1) Add 2 g of nano-silica with an average particle size of 80 nm into a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.1 g of 3-aminopropyltriethoxysilane, stir for 6 h at 45 °C, centrifuge, wash with deionized water 3 times and with absolute ethanol 3 times, and dry under vacuum to obtain amino-functionalized nano-silica;

[0034] (2) Add 3 g of glycidyl methacrylate, 0.1 g of azobisisobutyronitrile, and 2 g of amino-functionalized nano-silica into 10 g of 4-vinyl aniline, stir for 30 min at 35 °C, then add 0.1 g of Span-80 and 0.9 g of Tween-80, stir for 30 min, then raise the temperature to 55 °C, add 40 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 40 min, raise the temperature to 85 °C, stir for 6 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry under vacuum to obtain solid microspheres;

[0035] (3) Add 10 g of solid microspheres into 100 g of 1,2-dichloroethane, stir for 30 min, then add 0.5 g of glycidyl ether perfluorononyl ether, stir for 30 min at 50 °C, filter, wash with absolute ethanol 3 times, and dry under vacuum to obtain fluorinated solid microspheres;

[0036] (4) Add 10 g of fluorinated solid microspheres, 3.5 g of bisphenol A epoxy resin, 0.7 g of triethylenetetramine, and 0.35 g of trimethylolpropane triglycidyl ether to 25 g of acetone to obtain a coating solution. Then, use a spray gun to spray the coating solution onto the surface of a stainless-steel substrate. The nozzle is 25 cm away from the substrate, and the spraying pressure is 4.5 KPa. Cure it at 60 °C for 20 min first, and then at 80 °C for 2 h to obtain a superhydrophobic nano-coating.

[0037] Example 3:

[0038] (1) Add 2 g of nano-silica with an average particle size of 80 nm to a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.2 g of 3-aminopropyltriethoxysilane, stir at 45 °C for 6 h, centrifuge, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain amino-functionalized nano-silica;

[0039] (2) Add 5 g of glycidyl methacrylate, 0.2 g of azobisisobutyronitrile, and 3 g of amino-functionalized nano-silica to 10 g of 4-vinyl aniline, stir at 40 °C for 40 min, then add 0.2 g of Span-80 and 1.8 g of Tween-80, stir for 40 min, then raise the temperature to 60 °C, add 50 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 4 wt%, stir for 50 min, raise the temperature to 90 °C, stir for 7 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain solid microspheres;

[0040] (3) Add 10 g of solid microspheres to 120 g of 1,2-dichloroethane, stir for 30 min, then add 1 g of glycidyl ether perfluorononyl ether, stir at 55 °C for 40 min, filter, wash with absolute ethanol 3 times, and dry in vacuum to obtain fluorinated solid microspheres;

[0041] (4) Add 12 g of fluorinated solid microspheres, 4 g of bisphenol A epoxy resin, 1 g of triethylenetetramine, and 0.5 g of trimethylolpropane triglycidyl ether to 30 g of acetone to obtain a coating solution. Then, use a spray gun to spray the coating solution onto the surface of a stainless-steel substrate. The nozzle is 30 cm away from the substrate, and the spraying pressure is 5 KPa. Cure it at 60 °C for 20 min first, and then at 80 °C for 2 h to obtain a superhydrophobic nano-coating.

[0042] Comparative Example 1:

[0043] The difference between Comparative Example 1 and Example 2 is that styrene is used instead of 4-vinyl aniline;

[0044] The specific steps are as follows:

[0045] (1) Add 2 g of nano-silica with an average particle size of 80 nm to a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.1 g of 3-aminopropyltriethoxysilane, stir at 45 °C for 6 h, centrifuge, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain amino-functionalized nano-silica;

[0046] (2) Add 3 g of glycidyl methacrylate, 0.1 g of azobisisobutyronitrile, and 2 g of amino-functionalized nano-silica to 10 g of styrene, stir at 35 °C for 30 min, then add 0.1 g of Span-80 and 0.9 g of Tween-80, stir for 30 min, then raise the temperature to 55 °C, add 40 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 40 min, raise the temperature to 85 °C, stir for 6 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain solid microspheres;

[0047] (3) Add 10 g of solid microspheres to 100 g of 1,2-dichloroethane, stir for 30 min, then add 0.5 g of glycidyl ether perfluorononyl ether, stir at 50 °C for 30 min, filter, wash with absolute ethanol 3 times, and dry in vacuum to obtain fluorinated solid microspheres;

[0048] (4) Add 10 g of fluorinated solid microspheres, 3.5 g of bisphenol A epoxy resin, 0.7 g of triethylenetetramine, and 0.35 g of trimethylolpropane triglycidyl ether to 25 g of acetone to obtain a coating solution, then use a spray gun to spray the coating solution onto the surface of a stainless steel substrate, with the nozzle 25 cm away from the substrate and a spraying pressure of 4.5 KPa, cure at 60 °C for 20 min first, and then cure at 80 °C for 2 h to obtain a nano-coating.

[0049] Comparative Example 2:

[0050] The difference between Comparative Example 2 and Example 2 is that the silica is not amino-functionalized;

[0051] The specific steps are as follows:

[0052] (1) Add 3 g of glycidyl methacrylate, 0.1 g of azobisisobutyronitrile, and 2 g of nano-silica with an average particle size of 80 nm to 10 g of 4-vinylaniline, stir at 35 °C for 30 min, then add 0.1 g of Span-80 and 0.9 g of Tween-80, stir for 30 min, then raise the temperature to 55 °C, add 40 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 40 min, raise the temperature to 85 °C, stir for 6 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain solid microspheres;

[0053] (2) Add 10 g of solid microspheres to 100 g of 1,2-dichloroethane, stir for 30 min, then add 0.5 g of glycidyl ether perfluorononyl ether, stir at 50 °C for 30 min, filter, wash with absolute ethanol three times, and dry in vacuum to obtain fluorinated solid microspheres;

[0054] (3) Add 10 g of fluorinated solid microspheres, 3.5 g of bisphenol A epoxy resin, 0.7 g of triethylenetetramine, and 0.35 g of trimethylolpropane triglycidyl ether to 25 g of acetone to obtain a coating solution. Then use a spray gun to spray the coating solution onto the surface of a stainless steel substrate. The nozzle is 25 cm away from the substrate, and the spraying pressure is 4.5 KPa. First, cure at 60 °C for 20 min, and then cure at 80 °C for 2 h to obtain a nano-coating.

[0055] Comparative Example 3:

[0056] The difference between Comparative Example 3 and Example 2 is that glycidyl methacrylate was not added;

[0057] The specific steps are as follows:

[0058] (1) Add 2 g of nano-silica with an average particle size of 80 nm to a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.1 g of 3-aminopropyltriethoxysilane, stir at 45 °C for 6 h, centrifuge, and wash with deionized water three times and absolute ethanol three times, and dry in vacuum to obtain amino-functionalized nano-silica;

[0059] (2) Add 0.1 g of azobisisobutyronitrile and 2 g of amino-functionalized nano-silica to 13 g of 4-vinyl aniline, stir at 35 °C for 30 min, then add 0.1 g of Span-80 and 0.9 g of Tween-80, stir for 30 min, then raise the temperature to 55 °C, add 40 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 40 min, raise the temperature to 85 °C, stir for 6 h, cool to room temperature, filter, and wash with deionized water three times and absolute ethanol three times, and dry in vacuum to obtain solid microspheres;

[0060] (3) Add 10 g of solid microspheres to 100 g of 1,2-dichloroethane, stir for 30 min, then add 0.5 g of glycidyl ether perfluorononyl ether, stir at 50 °C for 30 min, filter, wash with absolute ethanol three times, and dry in vacuum to obtain fluorinated solid microspheres;

[0061] (4) Add 10 g of fluorinated solid microspheres, 3.5 g of bisphenol A epoxy resin, 0.7 g of triethylenetetramine, and 0.35 g of trimethylolpropane triglycidyl ether to 25 g of acetone to obtain a coating solution. Then, use a spray gun to spray the coating solution onto the surface of a stainless-steel substrate. The nozzle is 25 cm away from the substrate, and the spraying pressure is 4.5 KPa. First, cure at 60 °C for 20 min, and then cure at 80 °C for 2 h to obtain a nano-coating.

[0062] Comparative Example 4:

[0063] The difference between Comparative Example 3 and Example 2 is that the solid microspheres are not fluorinated;

[0064] The specific steps are as follows:

[0065] (1) Add 2 g of nano-silica with an average particle size of 80 nm to a mixed solution of 10 g of absolute ethanol and 20 g of deionized water, ultrasonicate for 20 min, then add 0.1 g of 3-aminopropyltriethoxysilane, stir at 45 °C for 6 h, centrifuge, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain amino-functionalized nano-silica;

[0066] (2) Add 3 g of glycidyl methacrylate, 0.1 g of azobisisobutyronitrile, and 2 g of amino-functionalized nano-silica to 10 g of 4-vinyl aniline, stir at 35 °C for 30 min, then add 0.1 g of Span-80 and 0.9 g of Tween-80, stir for 30 min, then raise the temperature to 55 °C, add 40 g of an aqueous solution of polyvinyl alcohol 1788 with a concentration of 3 wt%, stir for 40 min, raise the temperature to 85 °C, stir for 6 h, cool to room temperature, filter, wash with deionized water 3 times and with absolute ethanol 3 times, and dry in vacuum to obtain solid microspheres;

[0067] (4) Add 10 g of solid microspheres, 3.5 g of bisphenol A epoxy resin, 0.7 g of triethylenetetramine, and 0.35 g of trimethylolpropane triglycidyl ether to 25 g of acetone to obtain a coating solution. Then, use a spray gun to spray the coating solution onto the surface of a stainless-steel substrate. The nozzle is 25 cm away from the substrate, and the spraying pressure is 4.5 KPa. First, cure at 60 °C for 20 min, and then cure at 80 °C for 2 h to obtain a nano-coating.

[0068] Performance testing:

[0069] Wettability testing: Use a contact angle measuring instrument to test the contact angle and rolling angle of the sample. The results are shown in Table 1.

[0070] Surface roughness: Use a laser confocal microscope to measure the surface roughness of the sample. Each coating is measured in three directions, and the final roughness value is the average. The results are shown in Table 1.

[0071] Table 1 Wettability and Surface Roughness

[0072]

[0073] Data Analysis:

[0074] From the data of Examples 1-3 in Table 1, it can be seen that the superhydrophobic nano-coating prepared by the present invention has a contact angle as high as 159.2° and a rolling angle as low as 0.6°, showing excellent superhydrophobicity. Moreover, the surface roughness is relatively high, indicating that the surface has a rough structure. This structure is beneficial for the coating on the sample surface to capture air and form an air cushion on the coating surface, enabling the sample to obtain hydrophobicity.

[0075] From the data of Example 2 and Comparative Example 1 in Table 1, it can be seen that 4-vinyl aniline significantly increases the contact angle and decreases the rolling angle. This shows that 4-vinyl aniline helps to construct a uniform rough structure on the coating surface. This is mainly because 4-vinyl aniline provides amino reaction sites, and the amino reaction sites have three main functions. The first function is to form a crosslink with glycidyl methacrylate, making the solid microspheres more uniform. The second function is to provide grafting sites for glycidyl ether perfluorononyl ether to facilitate the introduction of low-surface-energy fluorine chains. The third function is to crosslink with the epoxy resin in the coating matrix, enabling the solid microspheres to be evenly distributed on the coating surface. The above three functions work together to promote excellent superhydrophobicity.

[0076] From the data of Example 2 and Comparative Example 2 in Table 1, it can be seen that the amination of silica helps to further improve the hydrophobicity. This is mainly because the aminated silica can be evenly dispersed on the surface of the solid microspheres, forming a nano-scale rough structure, which collaborates with the micron-scale rough structure caused by the solid microspheres to construct a micro-nano rough surface. The micro-nano rough surface has an important influence on the wettability of the coating.

[0077] From the data of Example 2 and Comparative Example 3 in Table 1, it can be seen that glycidyl methacrylate has a certain influence on the rolling angle of the coating. This is mainly because the crosslinking effect of glycidyl methacrylate will affect the distribution of aminated silica and the structure of the solid microspheres.

[0078] From the data of Example 2 and Comparative Example 4 in Table 1, it can be seen that the fluorination of the solid microspheres significantly reduces the wettability. This is mainly because low-surface-energy fluorine chains are introduced, and the low-surface-energy fluorine chains and the micro-nano structure work together to construct a low-wettability surface.

[0079] Those of ordinary skill in the art should understand that any discussion of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A superhydrophobic nano - coating, characterized in that, It is obtained by spraying a coating liquid on the surface of a substrate and then thermally curing it; The coating liquid includes the following components by weight parts: 8 - 12 parts of fluorinated solid microspheres, 3 - 4 parts of epoxy resin, 0.5 - 1 part of curing agent, 0.2 - 0.5 part of trimethylolpropane triglycidyl ether, and 20 - 30 parts of acetone; The preparation steps of the fluorinated solid microspheres are as follows: (1) Modify nano - silica with 3 - aminopropyltriethoxysilane to obtain amino - modified nano - silica; (2) Add glycidyl methacrylate, azobisisobutyronitrile, and amino - modified nano - silica into 4 - vinyl aniline, stir at 30 - 40 °C for 20 - 40 min, then add an emulsifier and stir for 20 - 40 min. Then raise the temperature to 50 - 60 °C, add an aqueous solution of polyvinyl alcohol, stir for 30 - 50 min, raise the temperature to 80 - 90 °C, stir for 5 - 7 h, cool to room temperature, filter, wash, and vacuum - dry to obtain solid microspheres; (3) Add the solid microspheres into 1,2 - dichloroethane, stir for 20 - 40 min, then add glycidyl ether perfluorononyl ether, stir at 45 - 55 °C for 20 - 40 min, filter, wash, and vacuum - dry to obtain fluorinated solid microspheres; In the step (2), the weight ratio of glycidyl methacrylate, azobisisobutyronitrile, amino - modified nano - silica, 4 - vinyl aniline, emulsifier, and aqueous solution of polyvinyl alcohol is 1 - 5:0.05 - 0.2:1 - 3:10:0.5 - 2:30 - 50.

2. The superhydrophobic nano-coating according to claim 1, wherein In the spraying process, the nozzle is 20 - 30 cm away from the substrate, and the spraying pressure is 4 - 5 kPa.

3. The superhydrophobic nano - coating according to claim 1, characterized in that, The epoxy resin is bisphenol A - type epoxy resin.

4. The superhydrophobic nano-coating according to claim 1, characterized in that, The curing agent is one or a mixture of diethylenetriamine and triethylenetetramine.

5. The superhydrophobic nano-coating according to claim 1, characterized in that, In the step (1), the weight ratio of 3 - aminopropyltriethoxysilane to nano - silica is 0.05 - 0.2:

2.

6. The superhydrophobic nano-coating according to claim 1, wherein In the step (1), the average particle size of the nano - silica is 20 - 100 nm.

7. The superhydrophobic nano-coating according to claim 1, wherein In the step (2), the concentration of the aqueous solution of polyvinyl alcohol is 2 wt% - 4 wt%.

8. The superhydrophobic nano-coating according to claim 1, wherein In the step (2), the emulsifier is a mixture of span - 80 and tween - 80 with a weight ratio of 1:

9.

9. The superhydrophobic nano-coating according to claim 1, wherein In the step (3), the weight ratio of the solid microspheres, 1,2 - dichloroethane, and glycidyl ether perfluorononyl ether is 10:80 - 120:0.1 - 1.

10. A method for preparing a superhydrophobic nano - coating according to any one of claims 1 - 9, characterized in that, The specific steps are as follows: Add fluorinated solid microspheres, bisphenol A - type epoxy resin, triethylenetetramine, and trimethylolpropane triglycidyl ether into acetone to obtain a coating liquid. Then use a spray gun to spray the coating liquid onto the surface of a stainless - steel substrate, cure it at 55 - 65 °C for 15 - 30 min first, and then cure it at 75 - 85 °C for 1.5 - 2.5 h to obtain a super - hydrophobic nano - coating.

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