Super-amphiphobic high-reflection coating and preparation method thereof

Abstract

The invention provides a preparation method of a super-amphiphobic high-reflection coating, and relates to the technical field of self-cleaning materials. A one-step method is adopted, and the core is to prepare functional super-amphiphobic particles with micro-nano structures. A micro-nano composite structure is constructed by a method of regrowing silicon dioxide on the surfaces of micron-scale barium sulfate, titanium dioxide or calcium carbonate particles, and then surface modification is performed to prepare the super-amphiphobic particles. And mixing the prepared particles with a water-based emulsion, alcohol-soluble or ester-soluble resin, a coalescing agent, a defoaming agent, a wetting leveling agent and an adhesive according to a certain ratio to prepare the coating. And finally, a coating with high reflectivity and super-amphiphobic performance is formed on the surface of the substrate, so that the contact angle of water drops and oil drops on the surface of the material is greater than 150 degrees.

Description

Technical Field

[0001] The present invention relates to the technical field of self-cleaning materials, and particularly to a superhydrophobic and superoleophobic highly reflective coating and a preparation method thereof. Background Art

[0002] With the intensification of global warming and energy shortage problems, reducing the energy consumption of buildings and improving energy utilization efficiency have become important demands that need to be solved urgently. The passive radiative cooling technology requires no additional energy consumption and can cool buildings and equipment by reflecting solar radiation and radiating heat in the atmospheric window range (8–13 μm), showing significant energy-saving effects.

[0003] In the actual application process, the existing radiative cooling materials often have the problem that their surfaces are easily contaminated, which leads to a rapid attenuation of their inherent radiative cooling performance and weakens their cooling effect.

[0004] Superhydrophobic and superoleophobic coatings have broad application prospects in the fields of anti-fouling, anti-corrosion, etc. due to their excellent hydrophobicity, oleophobicity and self-cleaning properties. Generally, superhydrophobic performance can be achieved by constructing micro-nano structures on the material surface and reducing the surface energy.

[0005] Barium sulfate (BaSO4), titanium dioxide (TiO2), calcium carbonate (CaCO 3) With characteristics such as high refractive index and wide bandgap, it can effectively reflect sunlight and has a high emissivity in the atmospheric window range, making it an ideal passive radiative cooling material. Barium sulfate, titanium dioxide, and calcium carbonate are hydrophilic by nature and need to be surface-modified to endow them with superhydrophobic and superoleophobic properties. Summary of the Invention

[0006] Aiming at the problems in the above-mentioned existing technologies, the present application proposes a superhydrophobic and superoleophobic highly reflective coating and a preparation method thereof to solve the problems of poor waterproof performance, easy contamination, and insufficient durability of the existing radiative cooling materials. The present invention adopts a one-step method, and the core lies in preparing functional superhydrophobic and superoleophobic particles with micro-nano structures. By regrowing silica on the surface of micron-scale barium sulfate, titanium dioxide or calcium carbonate particles, a micro-nano composite structure is constructed, and then surface modification is carried out to prepare superhydrophobic and superoleophobic particles. The prepared particles are mixed with an aqueous emulsion, an alcohol-soluble or ester-soluble resin, a film-forming aid, an antifoaming agent, a wetting and leveling agent, and an adhesive according to a certain ratio to prepare a coating. Finally, a coating with high reflectivity and superhydrophobic and superoleophobic properties is formed on the substrate surface, so that the contact angles of water droplets and oil droplets on the material surface are greater than 150°.

[0007] First, the construction of micro-nano structures and surface modification are integrated by a one-step method, which simplifies the process flow and improves production efficiency. By regrowing silica on the surface of micron-scale barium sulfate, titanium dioxide or calcium carbonate particles, a micro-nano composite structure is formed, enhancing the light scattering effect and achieving high reflectivity. Specifically, first, micron-scale barium sulfate, titanium dioxide or calcium carbonate nanoparticles are uniformly dispersed in a suitable solvent, such as a mixed solution of ethanol and water, and ultrasonic treatment is carried out for 30 minutes to ensure uniform dispersion of the particles. Subsequently, a silica precursor, such as tetraethyl orthosilicate, is slowly added, and the dropping rate is controlled at 1 mL / min, and continuous stirring is carried out at room temperature for 6 hours to enable uniform growth of silica on the surface of the nanoparticles, forming a micro-nano composite structure. During this process, ammonia water serves as a catalyst to adjust the reaction pH value and accelerate the hydrolysis and condensation reactions of silica. After the reaction is completed, unreacted substances are removed through centrifugation and washing steps, rinsed three times with ethanol, and finally dried in a vacuum drying oven at 60 °C for 8 hours to obtain micro-nano composite structure particles with a silica layer regrown on the surface.

[0008] The surface of barium sulfate (BaSO4), titanium dioxide (TiO2), and calcium carbonate (CaCO3) particles with different particle sizes (2 nm - 5 μm) is modified by chemical vapor deposition or liquid-phase alkylation methods using perfluorooctyltrichlorosilane, perfluorodecyltrichlorosilane, hexadecyltrichlorosilane, methyltriethoxysilane, vinyltriethoxysilane, etc., to make their surfaces superhydrophobic and oleophobic. Then, the modified nanoparticles are mixed with film-forming aids (including but not limited to diethylene glycol ethers, propylene glycol ethers, and N-methylpyrrolidone, etc.), defoamers (including but not limited to silicone-based, polyvinyl alcohol, etc.), wetting and leveling agents (including but not limited to ethylene glycol, isopropyl alcohol, modified polysiloxane, etc.) and adhesives (such as polyvinylidene fluoride, polycarbonate, polyethylene, polytetrafluoroethylene, polyurethane, polypropylene, polystyrene, polyvinyl alcohol, polyimide, etc.) to prepare a coating. Finally, the coating is applied to the surface of the treated substrate by spraying, drop coating, brushing or spin coating, and dried or cured to form a coating with superhydrophobic properties and passive radiative cooling function.

[0009] The advantages of the present invention are as follows:

[0010] The preparation method is simple and easy to implement, with strong universality: The preparation process of the present invention is simple, easy to control, and has universality. The prepared coating can be arbitrarily coated on the surface of various substrates to form a coating, without the need for additional high-cost equipment and complex preparation conditions. The obtained superhydrophobic and oleophobic and high-reflectivity coating has a self-cleaning effect, effectively solving the problems of low production efficiency, poor material durability, and easy contamination in the prior art.

[0011] The raw materials are low-cost and easily accessible: The raw materials required for preparing the coating are low-cost and easily accessible. By regulating the nano-particles of pigments and fillers with different particle sizes and types, a coating with high reflectivity in the solar spectrum range and high emissivity in the atmospheric transparent window range can be obtained.

[0012] The coating structure is optimized to achieve high reflectivity: The coating in the present invention can be applied to any surface by various simple methods such as spraying and brushing. Due to the large refractive index difference between the solid-phase nano-particles and the gas phase, high reflectivity in the solar spectrum range and high emissivity in the atmospheric transparent window can be achieved by using the optical backward porous scattering mechanism.

[0013] The super-hydrophobic and super-oleophobic properties are excellent and it has a self-cleaning function: The surface of the coating has a low surface energy, and the adhesion force between the pollutants and the coating is extremely low after the pollutants fall on the surface. It can effectively utilize natural conditions such as rainwater, morning fog, and wind in nature to remove pollutants without any additional cleaning and wiping, keeping the coating clean for a long time. Description of the Drawings

[0014] The present invention will be described in more detail below based on the embodiments and with reference to the drawings. Among them:

[0015] Figure 1 Shows a schematic diagram of the preparation method of the present invention. Detailed Description of the Invention

[0016] The present invention will be further described below with reference to the drawings.

[0017] Example 1

[0018] First, take barium sulfate particles with a particle size of 20 nm to 1 μm and evenly spread them on the quartz boat in the chemical vapor deposition reactor. Under nitrogen protection, heat the reactor to 200 °C, introduce trimethylchlorosilane vapor, and react for 1 hour to form an organosilane layer with low surface energy on the surface of the barium sulfate nano-particles. After the reaction, stop supplying gas, cool to room temperature, and take out the modified barium sulfate nano-particles. Mix 20 g of the modified nano-particles with 50 g of polyvinyl alcohol solution, and sequentially add 4 g of film-forming aid, 0.15 g of defoamer, and 0.4 g of wetting and leveling agent, and then stir evenly for 15 minutes to prepare a coating. Use the spraying method to evenly coat the coating on the surface of the aluminum alloy substrate and dry it at room temperature for 24 hours to form a radiative cooling coating with super-hydrophobic and super-oleophobic properties.

[0019] Example 2

[0020] First, take titanium dioxide particles with a particle size of 50 nm to 2 μm and place them in a chemical vapor deposition reactor. Under argon protection, heat the reactor to 220 °C, introduce perfluorooctyltrichlorosilane vapor, and react for 2 hours. After the reaction, cool to room temperature and take out the modified barium sulfate nanoparticles. Add 18 g of the modified nanoparticles to 60 g of an aqueous resin (acrylic resin), stir at a speed of 600 rpm for 40 minutes until evenly dispersed. Sequentially add 4 g of a film-forming aid, 0.15 g of an antifoaming agent, and 0.4 g of a wetting and leveling agent, and continue stirring for 20 minutes to prepare a uniform coating. Using the drop-coating method, evenly coat the coating on the surface of the substrate and dry at room temperature to form a superhydrophobic and superoleophobic radiative cooling coating.

[0021] Example 3

[0022] On the surface of a solid substrate, mix 40 g of an epoxy resin (Component A) and 20 g of a curing agent (Component B) in a ratio of 2:1, coat evenly to form an adhesive layer, and leave the adhesive surface side exposed to the air for standby. Take calcium carbonate particles with a particle size of 10 nm to 50 nm and place them in a chemical vapor deposition reactor. Under nitrogen protection, heat the reactor to 210 °C, introduce perfluorooctylethoxysilane vapor, and react for 1.5 hours. After the reaction, cool to room temperature and take out the modified calcium carbonate nanoparticles. Add 20 g of the modified superhydrophobic and superoleophobic functional particles to 35 g of a polyvinylidene fluoride solution, add 6 g of a radiative cooling filler, stir at a speed of 500 rpm for 30 minutes until evenly dispersed. Sequentially add 6 g of a film-forming aid, 0.2 g of an antifoaming agent, and 0.46 g of a wetting and leveling agent, and continue stirring for 15 minutes to prepare a uniform coating. Using the spin-coating method, evenly coat the coating on the surface of the substrate and cure at 130 °C for 30 minutes to form a radiative cooling coating with superhydrophobic and superoleophobic properties.

[0023] Example 4

[0024] Disperse barium sulfate particles with a particle size of 10 nm to 500 nm in anhydrous ethanol and use ultrasonic treatment for 30 minutes to ensure uniform dispersion. Under stirring conditions, add perfluorooctyltrichlorosilane and continue stirring for 5 hours to make it react with the surface of the barium sulfate nanoparticles. After the reaction is completed, filter and wash, rinse three times with anhydrous ethanol, and finally dry in a vacuum drying oven at 60 °C for 8 hours to obtain the modified barium sulfate nanoparticles. Add 20 g of the modified barium sulfate nanoparticles to 50 g of an aqueous resin (polyvinyl alcohol) solution, stir at a speed of 500 rpm for 30 minutes until evenly dispersed. Sequentially add 4 g of a film-forming aid, 0.15 g of an antifoaming agent, and 0.4 g of a wetting and leveling agent, and continue stirring for 20 minutes to prepare a uniform coating. Using the spraying method, evenly coat the coating on the surface of the substrate and dry at room temperature to form a superhydrophobic and superoleophobic radiative cooling coating.

[0025] Example 5

[0026] Disperse titanium dioxide particles with a particle size of 100 nm to 1 μm in toluene and ultrasonically treat for 30 minutes. Under stirring conditions, add dodecyltrichlorosilane and continue stirring for 5 hours to cause an alkylation reaction on the surface of the titanium dioxide nanoparticles. Add hydrochloric acid to adjust the pH of the solution to 4 to promote the reaction. After the reaction is completed, filter and wash, rinse three times with toluene, and dry to obtain modified titanium dioxide nanoparticles. Mix 15 g of the modified titanium dioxide nanoparticles with 60 g of acrylic resin, add 3 g of film-forming aid, 0.1 g of defoamer, and 0.3 g of wetting and leveling agent, and stir evenly to prepare a uniform coating. Adopt the drop-coating method to evenly coat the coating on the surface of the substrate and dry at room temperature to form a superhydrophobic and superoleophobic radiative cooling coating.

[0027] Example 6

[0028] Disperse barium sulfate particles with a particle size of 10 nm to 5 μm in absolute ethanol and ultrasonically treat for 30 minutes. Under stirring conditions, add hexadecyltrichlorosilane and continue stirring for 5 hours to cause a reaction on the surface of the barium sulfate nanoparticles. Add triethylamine to adjust the pH of the solution to 5 to promote the reaction. After the reaction is completed, filter and wash, rinse three times with absolute ethanol, and dry to obtain modified barium sulfate nanoparticles. Mix 20 g of the modified nanoparticles with 100 g of epoxy resin solution, sequentially add 4 g of film-forming aid, 0.15 g of defoamer, and 0.4 g of wetting and leveling agent, and continue stirring for 20 minutes to prepare a uniform coating. Adopt the spin-coating method to evenly coat the coating on the surface of the pre-treated substrate and cure at 130 °C for 30 minutes to form a radiative cooling coating with superhydrophobic and superoleophobic properties.

[0029] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A preparation method of a superhydrophobic and superoleophobic highly reflective coating, characterized in that, It includes the following steps: Regrow silica on the surface of micron-scale particles to construct a micro-nano composite structure, and then conduct surface modification to prepare superhydrophobic and superoleophobic particles; prepare the superhydrophobic and superoleophobic particles into a coating, and finally form a coating with high reflectivity and superhydrophobic and superoleophobic properties on the substrate surface.

2. The preparation method of the super-biphobic and highly reflective coating according to claim 1, wherein The micron-scale particles include at least one of barium sulfate, titanium dioxide or calcium carbonate.

3. The preparation method of the superhydrophobic and superoleophobic highly reflective coating according to claim 1, characterized in that, The method of preparing the superhydrophobic and superoleophobic particles into a coating includes mixing the superhydrophobic and superoleophobic particles with an aqueous emulsion, an alcohol-soluble or ester-soluble resin, a film-forming aid, an antifoaming agent, a wetting and leveling agent, and an adhesive in a certain ratio.

4. The preparation method of the super-biphobic and highly reflective coating according to claim 1, wherein Integrate the construction of the micro-nano structure and surface modification together by a one-step method to prepare superhydrophobic and superoleophobic particles.

5. The preparation method of the superhydrophobic and superoleophobic highly reflective coating according to claim 4, characterized in that, First, uniformly disperse barium sulfate, titanium dioxide or calcium carbonate nanoparticles at the micron scale in a solvent, and use ultrasonic treatment to ensure the uniform dispersion of the particles; subsequently, slowly add a silica precursor to uniformly grow silica on the surface of the nanoparticles to form a micro-nano composite structure.

6. The preparation method of the super-hydrophobic and super-oleophobic highly reflective coating according to claim 5, wherein, Use ammonia water as a catalyst to adjust the reaction pH value and accelerate the hydrolysis and condensation reaction of silica.

7. The preparation method of the super-biphobic and highly reflective coating according to claim 4, characterized in that, Adopt chemical vapor deposition or liquid-phase alkylation to conduct surface modification on barium sulfate (BaSO4), titanium dioxide (TiO2), calcium carbonate (CaCO3) particles with different particle sizes, using perfluorooctyltrichlorosilane, perfluorodecyltrichlorosilane, hexadecyltrichlorosilane, methyltriethoxysilane or vinyltriethoxysilane to make their surfaces superhydrophobic and superoleophobic; then, mix the modified nanoparticles with a film-forming aid, an antifoaming agent, a wetting and leveling agent, and an adhesive to prepare a coating; finally, apply the coating to the surface of the treated substrate by spraying, drop coating, brushing or spin coating, and dry or cure it to form a coating with superhydrophobic properties and passive radiative cooling function.

8. The preparation method of the superhydrophobic and superoleophobic highly reflective coating according to claim 7, wherein, The film-forming aids include but are not limited to diethylene glycol ethers, propylene glycol ethers and N-methylpyrrolidone.

9. The preparation method of the superhydrophobic and superoleophobic highly reflective coating according to claim 7, characterized in that, The antifoaming agents include but are not limited to silicone-based ones, polyvinyl alcohol; the wetting and leveling agents include but are not limited to ethylene glycol, isopropyl alcohol, modified polysiloxane.

10. A super-hydrophobic and super-oleophobic highly reflective coating, characterized in that, Obtained by using the preparation method according to any one of claims 1-9.

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