A super-hydrophobic coating material and a method for preparing the same

Abstract

The application discloses a kind of super-hydrophobic coating materials and preparation method thereof;Preparation method includes: step one, preparation modified milli-nano structure metal-based particle: millimeter metal powder particle is used as matrix particle, and acid etching method is used to build nano structure on the surface of matrix particle, then it is added to low surface energy solution and is modified by chemical modification method;Step two, the material obtained in step one is combined with adhesive, and a super-hydrophobic coating material is obtained;The application can significantly improve the physical and mechanical properties while realizing the super-hydrophobic performance of the coating;Moreover, the nano structure built in situ on the surface of the millimeter particle has strong chemical interaction force between the whole particle, and it is not easy to break and separate each other, with good structural stability, which is another advantage of the super-hydrophobic coating prepared by the application.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic coating technology, and in particular to a superhydrophobic coating material and its preparation method. Background Technology

[0002] Superhydrophobic coatings, due to their excellent self-cleaning properties, fluid transport drag reduction, anti-icing, and corrosion resistance, have broad application prospects in construction, energy, communications, and power industries. For example, in oil extraction, the emergence of superhydrophobic materials provides a new technical approach for oil-water separation. In power supply systems, the anti-condensation properties of superhydrophobic surfaces can effectively extend the service life of transmission lines, enabling them to supply power normally in extremely cold environments. In industrial production, superhydrophobic coatings can be effectively used for oil and dust protection on glass surfaces, and for waterproofing and anti-fogging of optical instrument lenses. Metal materials coated with superhydrophobic coatings exhibit excellent corrosion resistance, significantly extending their service life under the same service conditions.

[0003] Due to the unique properties and functions of superhydrophobic coatings, their precise construction has become a research hotspot. Over the past 20 years, numerous scholars have conducted in-depth research on superhydrophobic coatings, demonstrating that constructing a "concave-convex micro-nano" structure with a lotus leaf-like surface is key to achieving superhydrophobic properties. Currently, a large number of superhydrophobic coating construction methods have emerged, such as self-assembly, spraying, phase separation, sol-gel methods, and electrochemical deposition. Among these, spraying is favored due to its simplicity, lack of precision instruments, low cost, and ease of industrialization. However, to achieve the crucial factor of constructing micro-nano structures on the coating surface for superhydrophobic properties, a large amount of nano-pigments, such as nano-silica, carbon nanowires, and zinc oxide whiskers, must be incorporated into the coating system, with pigment volume concentrations significantly exceeding critical values. Lower resin content makes it difficult to completely encapsulate the pigments, leading to a "powdering" phenomenon in the coating and making it susceptible to damage from scratches, impacts, etc., resulting in the loss of superhydrophobicity. For example, patent CN111334136A discloses a long-lasting oil-resistant coating that simply combines a resin binder with a nanoparticle solution, which also lacks high wear resistance. Therefore, no superhydrophobic coating suitable for large-scale industrial application has yet been found. Summary of the Invention

[0004] The purpose of this invention is to provide a superhydrophobic coating material and its preparation method, thereby solving the problem that existing superhydrophobic coatings have poor mechanical properties and are not suitable for large-scale industrial applications.

[0005] This invention is achieved by providing a method for preparing a superhydrophobic coating material, the method comprising the following steps:

[0006] Step 1: Preparation of modified milli-nano structured metal-based particles: Using millimeter-sized metal powder particles as matrix particles, the metal-based particles are etched with a mixed solution of water, hydrochloric acid and hydrofluoric acid with a volume ratio of (80-100):(8-10):1 to construct nanostructures on the surface of the matrix particles. Then, the particles are added to a low surface energy solution for chemical modification.

[0007] Step 2: The material obtained in Step 1 is combined with the adhesive to obtain a superhydrophobic coating material.

[0008] This invention uses millimeter-sized metal powder particles as the matrix particles and constructs nanostructures on their surface using an acid etching method. This process prepares milli-nano structured particles by building nanostructures on the surface of millimeter-sized particles. These nanostructures are then modified using a chemical modification method to prepare modified second-order milli-nano structured metal-based particles. These modified particles are then mixed with a polymer binder to form a film. This achieves superhydrophobic properties while significantly improving the physical and mechanical properties of the coating. Furthermore, the nanostructures constructed in situ on the surface of millimeter-sized particles exhibit strong chemical interactions with the overall particles, making them difficult to break apart and possessing excellent structural stability. This is another advantage of the superhydrophobic coating prepared by this invention.

[0009] A further technical solution of the present invention is as follows: In step one, the etching time is 10-60 minutes, and after etching, the sample is rinsed with deionized water and dried for later use. The mixed solution of the present invention provides high efficiency for acid etching and can achieve the etching of nanoscale surface layers onto millimeter-sized metal powder particles.

[0010] A further technical solution of the present invention is that the ratio of the mass of the metal-based particles, the volume of the mixed solution, and the volume of the low surface energy solution is (2-5) g : (94-125) mL : (12-20) mL. The low surface energy solution in this invention comprehensively modifies the active sites on the surface of the metal particles, resulting in sufficient modification. Furthermore, the adhesive can adhere to the metal particles without covering them.

[0011] A further technical solution of the present invention is that the millimeter-sized metal powder particles in step one include at least one of millimeter-sized aluminum powder particles, millimeter-sized copper powder particles, and millimeter-sized zinc powder. These metal powder particles are reactive metals and are easily etched by acid to form a nanoscale surface layer.

[0012] A further technical solution of the present invention is: the low surface energy solution includes at least one of the following: a hexane solution containing trichloro1H,2H,3H-heptadecylsilane, an ethanol solution containing palmitic acid, and an ethanol solution containing stearic acid.

[0013] A further technical solution of the present invention is: in step one, the millimeter-sized metal powder particles are cleaned with deionized water and anhydrous ethanol respectively, and then acid etching is performed.

[0014] A further technical solution of the present invention is as follows: the chemical modification in step one is: adding the etched metal-based particles to a low surface energy solution and letting it stand for 12 hours. The superhydrophobic effect exceeds that of other low surface energy solutions.

[0015] A further technical solution of the present invention is as follows: the adhesive in step two is AB glue, which is mixed at a mass ratio of 1:1 and coated to a thickness of 2mm to 3mm to obtain a glue film. The material obtained in step one is dispersed on the surface of the glue film, embedded in the glue film, and cured for 24 hours to obtain a superhydrophobic coating material. This method is convenient to operate and easy to prepare.

[0016] A further technical solution of the present invention is that the mass ratio of the material obtained in step one to the adhesive is (1.5-4):1.

[0017] The present invention also provides a superhydrophobic coating material, which is prepared by the preparation method described above.

[0018] Inspiringly, despite its extremely low resin content, the exposed, protruding sand particles in architectural exterior wall mortar paint can still adhere to each other to form a continuous, integral coating that firmly adheres to the wall surface. This is due to the large size and low specific surface area of ​​the millimeter-sized sand particles, which maintain excellent adhesion between particles and between particles and the substrate even at high pigment volume concentrations, thus forming a hard, integral coating. Therefore, if nanostructures can be constructed on the surface of millimeter-sized particles to prepare milli-nano structured particles, and these particles can be used as functional pigments to mix with polymers to form films, it is expected that while achieving superhydrophobic properties, the physical and mechanical properties of the coating can also be significantly improved.

[0019] The beneficial effects of this invention are as follows: This invention uses millimeter-sized metal powder particles as the matrix particles, and constructs nanostructures on their surface using an acid etching method. This process prepares milli-nano structured particles by building nanostructures on the surface of millimeter-sized particles. These nanostructures are then modified using a chemical modification method to prepare modified second-order milli-nano structured metal-based particles. These modified particles are then mixed with a polymer binder to form a film. This achieves superhydrophobic coating properties while significantly improving its physical and mechanical properties. Furthermore, the nanostructures constructed in situ on the surface of millimeter-sized particles exhibit strong chemical interactions with the overall particles, making them difficult to break apart and exhibiting good structural stability. This is another advantage of the superhydrophobic coating prepared by this invention. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for preparing a superhydrophobic coating material provided by the present invention;

[0021] Figure 2 The surface microstructure and chemical composition of the milli-nano structured aluminum-based particles obtained in Example 1 of this invention;

[0022] Figure 3 This is a test diagram of the hydrophobic properties of the superhydrophobic coating material obtained in Embodiment 1 of the present invention;

[0023] Figure 4 This is a graph showing the test results of the flexibility and impact resistance of the superhydrophobic coating material obtained in Embodiment 1 of the present invention. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0026] This invention provides a method for preparing a superhydrophobic coating material, the method comprising the following steps:

[0027] Step 1: Preparation of modified milli-nano structured metal-based particles: Using millimeter-sized metal powder particles as matrix particles, the metal-based particles are etched with a mixed solution of water, hydrochloric acid and hydrofluoric acid with a volume ratio of (80-100):(8-10):1 to construct nanostructures on the surface of the matrix particles. Then, the particles are added to a low surface energy solution for chemical modification.

[0028] Step 2: The material obtained in Step 1 is combined with the adhesive to obtain a superhydrophobic coating material.

[0029] Furthermore, in step one, the etching time is 10-60 minutes, and after etching, the sample is rinsed with deionized water and dried for later use.

[0030] Furthermore, the mass ratio of the metal-based particles, the volume of the mixed solution, and the volume ratio of the low surface energy solution is: (2-5) g : (94-125) mL : (12-20) mL.

[0031] Furthermore, the millimeter-sized metal powder particles in step one include at least one of millimeter-sized aluminum powder particles, millimeter-sized copper powder particles, and millimeter-sized zinc powder.

[0032] Furthermore, the low surface energy solution includes at least one of the following: a hexane solution containing trichloro1H,2H,3H-heptadecylsilane, an ethanol solution containing palmitic acid, and an ethanol solution containing stearic acid.

[0033] Furthermore, in step one, the millimeter-sized metal powder particles are cleaned with deionized water and anhydrous ethanol, respectively, and then acid etched.

[0034] Furthermore, the chemical modification in step one is as follows: the etched metal-based particles are added to a hexane solution of 1% by mass of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12 hours.

[0035] Furthermore, in step two, the adhesive is AB glue, which is mixed at a mass ratio of 1:1 and coated to a thickness of 2mm to 3mm to obtain a film. The material obtained in step one is dispersed on the surface of the film, embedded in the film, and cured for 24 hours to obtain a superhydrophobic coating material.

[0036] Furthermore, the mass ratio of the material obtained in step one to the adhesive is (1.5 to 4): 1.

[0037] Example 1:

[0038] A method for preparing a superhydrophobic coating material includes the following steps: 2g of millimeter-sized aluminum-based particles are cleaned with deionized water and anhydrous ethanol, respectively; the aluminum-based particles are etched for 35 min with a 111mL mixed solution of water, hydrochloric acid, and hydrofluoric acid (volume ratio of 100:10:1); after etching, they are cleaned with deionized water and dried for later use; the etched aluminum-based particles are added to 15mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12h for modification to obtain fluorosilane-modified milli-nano structured aluminum-based particles.

[0039] Then, a superhydrophobic coating was constructed using low surface energy milli-nano structured aluminum-based particles: Component A and Component B were mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive was coated onto the surface of a polished tinplate to prepare an adhesive film with a thickness of 2-3 mm. The fluorosilane-modified milli-nano structured aluminum-based particles were uniformly dispersed on the surface of the adhesive film at a mass ratio of 2:1 to the AB adhesive, and then lightly pressed into the adhesive film. After curing for 24 hours, a superhydrophobic coating material was obtained.

[0040] Example 2:

[0041] A method for preparing a superhydrophobic coating material includes the following steps: 3g of millimeter-sized copper-based particles are cleaned with deionized water and anhydrous ethanol, respectively; the copper-based particles are etched for 55 min with a 111 mL mixed solution of water, hydrochloric acid, and hydrofluoric acid (volume ratio of 100:10:1); after etching, they are cleaned with deionized water and dried for later use; the etched copper-based particles are added to 12 mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12 h to obtain fluorosilane-modified milli-nano structured copper-based particles.

[0042] Then, a superhydrophobic coating was constructed using low surface energy milli-nano structured copper-based particles: Component A and Component B were mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive was coated onto the surface of a polished tinplate to prepare an adhesive film with a thickness of 2-3 mm. The fluorosilane-modified milli-nano structured copper-based particles were uniformly dispersed on the surface of the adhesive film at a mass ratio of 2:1 with the AB adhesive, and then lightly pressed into the adhesive film. After curing for 24 hours, a superhydrophobic coating material was obtained.

[0043] Example 3:

[0044] A method for preparing a superhydrophobic coating material includes the following steps: 4g of millimeter-sized zinc-based particles are cleaned with deionized water and anhydrous ethanol, respectively; the zinc-based particles are etched for 45 min with a 111 mL mixed solution of water, hydrochloric acid, and hydrofluoric acid (volume ratio of 100:10:1); after etching, they are cleaned with deionized water and dried for later use; the etched zinc-based particles are added to 20 mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12 h for modification to obtain fluorosilane-modified milli-nano structured zinc-based particles.

[0045] Then, a superhydrophobic coating was constructed using low surface energy milli-nano structured zinc-based particles: Component A and Component B were mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive was then coated onto a polished tinplate surface to prepare an adhesive film with a thickness of 2-3 mm. The fluorosilane-modified milli-nano structured zinc-based particles were uniformly dispersed on the adhesive film surface at a mass ratio of 2:1 to the AB adhesive, and then lightly pressed into the adhesive film. After curing for 24 hours, a superhydrophobic coating material was obtained.

[0046] Example 4:

[0047] A method for preparing a superhydrophobic coating material includes the following steps: 2g of millimeter-sized aluminum-based particles are cleaned with deionized water and anhydrous ethanol, respectively; the aluminum-based particles are etched for 35 min with a 94mL mixed solution of water, hydrochloric acid, and hydrofluoric acid (volume ratio of 85:8:1); after etching, they are cleaned with deionized water and dried for later use; the etched aluminum-based particles are added to 15mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12 h for modification to obtain fluorosilane-modified milli-nano structured aluminum-based particles.

[0048] Then, a superhydrophobic coating was constructed using low surface energy milli-nano structured aluminum-based particles: Component A and Component B were mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive was coated onto the surface of a polished tinplate to prepare an adhesive film with a thickness of 2-3 mm. The fluorosilane-modified milli-nano structured aluminum-based particles were uniformly dispersed on the surface of the adhesive film at a mass ratio of 2:1 to the AB adhesive, and then lightly pressed into the adhesive film. After curing for 24 hours, a superhydrophobic coating material was obtained.

[0049] Example 5:

[0050] A method for preparing a superhydrophobic coating material includes the following steps: 2g of millimeter-sized aluminum-based particles are cleaned with deionized water and anhydrous ethanol, respectively; the aluminum-based particles are etched for 35 min with a 105mL mixed solution of water, hydrochloric acid, and hydrofluoric acid (volume ratio of 95:9:1); after etching, they are cleaned with deionized water and dried for later use; the etched aluminum-based particles are added to 15mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane and allowed to stand for 12 h to obtain fluorosilane-modified milli-nano structured aluminum-based particles.

[0051] Then, a superhydrophobic coating was constructed using low surface energy milli-nano structured aluminum-based particles: Component A and Component B were mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive was coated onto the surface of a polished tinplate to prepare an adhesive film with a thickness of 2-3 mm. The fluorosilane-modified milli-nano structured aluminum-based particles were uniformly dispersed on the surface of the adhesive film at a mass ratio of 2:1 to the AB adhesive, and then lightly pressed into the adhesive film. After curing for 24 hours, a superhydrophobic coating material was obtained.

[0052] Comparative Example 1:

[0053] A method for preparing a superhydrophobic coating material includes the following steps: 2g of millimeter-sized aluminum-based particles are cleaned with deionized water and anhydrous ethanol; the aluminum-based particles are etched for 35 min with a 112mL mixed solution of water and hydrochloric acid (volume ratio 15:1); after etching, they are cleaned with deionized water and dried; the etched aluminum-based particles are added to 15mL of a 1% (w / w) solution of trichloro-1H,2H,3H-heptadecylsilane in n-hexane and allowed to stand for 12 h to obtain fluorosilane-modified aluminum-based particles. Testing revealed that the surface layer of the aluminum-based particles is not nanoscale.

[0054] Component A and component B are mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive is then coated onto a polished tinplate surface to prepare an adhesive film with a thickness of 2–3 mm. Fluorosilane-modified aluminum-based particles are then uniformly dispersed on the adhesive film surface at a mass ratio of 2:1 to the AB adhesive, and gently pressed into the film. The mixture is then cured for 24 hours to obtain a coating material. This coating material does not possess superhydrophobic properties.

[0055] Comparative Example 2:

[0056] A method for preparing a superhydrophobic coating material includes the following steps: 2g of millimeter-sized aluminum-based particles are cleaned with deionized water and anhydrous ethanol; the aluminum-based particles are etched for 35 min with a 111mL mixed solution of water, hydrochloric acid, and sulfuric acid (volume ratio 100:10:1); after etching, they are cleaned with deionized water and dried; the etched aluminum-based particles are added to 15mL of a 1% (w / w) hexane solution of trichloro1H,2H,3H-heptadecylsilane, and allowed to stand for 12 h to obtain fluorosilane-modified aluminum-based particles. Testing revealed no nanostructures on the surface of the aluminum-based particles.

[0057] Component A and component B are mixed uniformly at a mass ratio of 1:1 to obtain AB adhesive. The AB adhesive is then coated onto a polished tinplate surface to prepare an adhesive film with a thickness of 2–3 mm. Fluorosilane-modified aluminum-based particles are then uniformly dispersed on the adhesive film surface at a mass ratio of 2:1 to the AB adhesive, and gently pressed into the film. The mixture is then cured for 24 hours to obtain a coating material. This coating material does not possess superhydrophobic properties.

[0058] Performance testing:

[0059] The surface morphology and chemical composition of the fluorosilane-modified nanostructured aluminum-based particles obtained in Example 1 of this invention were analyzed: the microstructure and surface elemental composition of the particles were characterized using a field emission scanning electron microscope (ZEISS Sigma300SEM, Germany) equipped with a Smartedx energy dispersive spectrometer (EDS). During testing, the samples were imaged using an SE2 secondary electron detector at an accelerating voltage of 3 kV. EDS spectra were measured at an accelerating voltage of 15 kV and a working distance of 8.5 mm. Simultaneously, the chemical composition of the particle surface was analyzed at room temperature using an X-ray photoelectron spectroscopy (XPS) equipped with a monochromatic Al Kα source (hν = 1486.6 eV). During testing, the power was 12 kV × 6 mA, and the spot size was 400 μm.

[0060] The results are as follows Figure 2 As shown, Figure 2 Images a through c show the surface microstructures of acid-etched aluminum particles of different sizes after modification. It can be seen that the modified particle surface exhibits numerous uneven porous and grooved structures, with groove widths ranging from tens of nanometers to several micrometers, lengths from several micrometers to tens of micrometers, and depths from several nanometers to several micrometers. This is due to the intense chemical reaction between the acid and the aluminum-based particles during the etching process, releasing gases and causing the particle surface to dissolve and corrode. Simultaneously, a large number of nanoscale white granular substances were also found to cover the particle surface. EDS analysis of these substances yielded the following results: Figure 2 As shown in d~g, F, Si, and Cl were found to be relatively uniformly distributed on the surface of the aluminum-based particles, with mass fractions of 81.23%, 15.09%, and 3.69%, respectively. Figure 2 h). This is because during the modification process, trichloro1H,2H,3H-heptadecylsilane (FDTS) hydrolyzes and reacts with the hydroxyl groups on the surface of the aluminum-based particles, thus adhering to their surface. A schematic diagram of the reaction principle is shown below. Figure 2 As shown in i. However, the hydroxyl group density on the surface of aluminum particles is limited, so some FDTS self-assembled during the modification process, leading to FDTS aggregation and the formation of white granular substances on the particle surface. Analysis of SEM and EDS images shows that this experiment has successfully constructed fluorinated siliconized second-order milli-nano structured aluminum-based particles.

[0061] The performance of the superhydrophobic coating material obtained in Example 1 was characterized:

[0062] Hydrophobicity: The static and dynamic water contact angles of the coating were characterized using an optical water contact angle meter (Lauda Scientific LSA100, Germany). The final static water contact angle was represented by the average of the test results from four different regions of the coating.

[0063] The results are as follows Figure 3 As shown, by Figure 3 As shown in Figure a, the water droplets are distributed in a spherical shape on the coating surface. The water contact angles in the four different regions reach 153.8°, 153°, 152.2°, and 153.1°, respectively, with an average of 153°, which is higher than the critical value of 150°, thus achieving superhydrophobic properties. To determine the hydrophobic stability of the coating, the dynamic water contact angle of the coating was also tested in this experiment, and the results are as follows: Figure 3 As shown in Figure b, the water contact angle remained stable at approximately 153.1° during the test, indicating good hydrophobic stability. Furthermore, to further verify the coating's anti-wetting properties, this study also tested the wetting of the coating surface with crystal violet solution, methyl orange solution, methylene blue solution, clay slurry, NaCl solution, cola, tea, and water. The results are as follows: Figure 3 As shown in c, all droplets on the coating surface are spherical and can roll as the coating is tilted, exhibiting superior anti-wetting properties. These results demonstrate that a stable superhydrophobic coating was prepared using milli-nano structured particles as functional pigments. This is because the coating surface constructed from milli-nano structured aluminum-based particles possesses a uniform "micro-nano" structure with a strong air-holding capacity, forming a non-polar air layer. Water droplets falling on this surface are in a hydrophobic environment and, under the influence of surface tension, condense into spherical liquids, forming a water contact angle greater than 150° with the coating surface, allowing them to roll off at a relatively small angle. This stable superhydrophobic property provides crucial assurance for the coating to achieve self-cleaning, anti-icing, and anti-corrosion functions.

[0064] Impact resistance: The impact resistance of the coating was characterized using a paint film impact tester (BGD 302, China) according to GB / T1732-1993, "Test Method for Impact Resistance of Paint Films". During the test, the painted side of the test panel was placed flat on an iron plate, and a weight was dropped from a certain height onto the coating in a free-fall manner. The presence of cracks, peeling, or other defects was observed at the impact point, and the hydrophobicity was tested.

[0065] The results are as follows Figure 4 As shown, the coating of Example 1 was bent 180° around a shaft with a diameter of 2mm against it. No cracks or peeling were observed on the bent section of the coating. Figure 4As shown in Figure a, the flexibility reaches 2 mm. Since water droplets are difficult to retain at curved interfaces, the hydrophobicity is tested by observing water droplet residue. When a water droplet is dropped onto the curved section, the droplet deforms upon impact and then bounces off, leaving no adsorption residue on the surface. This indicates that the coating still has excellent hydrophobicity on the curved surface and that the coating has strong resistance to bending.

[0066] Superhydrophobic coatings typically consist of micro / nano-level roughened structures. While this structure contributes to the superhydrophobic effect, these simple blends of nanoparticles, due to low resin content and loose pigment bonding, are susceptible to physical impact damage and can lose their superhydrophobic properties. Impact resistance refers to the coating's ability to withstand rapid deformation under high-speed gravity without cracking or detaching from the metal substrate. Test results are as follows... Figure 4 As shown in b, under impacts from hammers of varying heights, the coating surface showed no cracks or peeling. This is attributed to the large overall size of the aluminum particles, which, under the action of the resin, exhibit better adhesion between particles and between particles and the substrate, making them less prone to breakage and separation, thus demonstrating good structural stability. The hydrophobicity of the coating was assessed by observing the movement of water droplets at the impact dents. The results showed that water droplets could easily roll over the dents formed by impacts of 10 kg·cm and 15 kg·cm without leaving a mark. However, on the dents formed by an impact intensity of 20 kg·m, water droplets encountered resistance as they rolled over the dents, leaving a small amount of liquid residue on the surface. Therefore, the coating exhibits an impact resistance of 15 kg·m, indicating good impact resistance. This is because the nanostructures constructed in situ on the surface of millimeter-sized particles have strong chemical interactions with the overall particles, maintaining a good microscopic rough structure even under external impacts, thus preserving the surface's excellent superhydrophobic properties. The superior adhesion resulting from the low specific surface area of ​​the large-sized particles, combined with the excellent mechanical properties of the coating, provides a solid foundation for its outdoor applications.

[0067] Flexibility: According to GB / T1731-2020 "Test Method for Flexibility of Coating Films", the bending resistance of the coating was evaluated using a coating film flexibility tester (BGD560, China). With the coating surface facing upwards, the coating sample was pressed firmly against a shaft of specified diameter on the flexibility tester with both hands. The sample was bent around the shaft at a steady speed within 2-3 seconds, and the presence of cracks, peeling, or other defects in the coating film was observed. The aluminum particle coating was then bent 180° around a 2mm diameter shaft. If no cracks or peeling were observed in the bent section of the coating, the coating was considered compliant. Figure 4 As shown in figure a, the flexibility reaches 2mm.

[0068] This invention uses millimeter-sized aluminum powder particles as the matrix particles and constructs nanostructures on their surface using an acid etching method. These nanostructures are then used to prepare milli-nano structured particles, which are further modified using chemical methods to prepare fluorosilane-modified second-order milli-nano structured aluminum-based particles. These particles are then used as functional pigments and mixed with polymers to form films. This process achieves superhydrophobic coating properties while significantly improving its physical and mechanical properties. Furthermore, the nanostructures constructed in situ on the millimeter-sized particle surface exhibit strong chemical interactions with the overall particles, making them difficult to break apart and demonstrating excellent structural stability. This is another advantage of the superhydrophobic coating prepared by this invention.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a superhydrophobic coating material, characterized in that, The method includes the following steps: Step 1: Preparation of modified milli-nano structured metal-based particles: Using millimeter-sized metal powder particles as matrix particles, the metal-based particles are etched with a mixed solution of water, hydrochloric acid and hydrofluoric acid with a volume ratio of (80-100):(8-10):1 to construct nanostructures on the surface of the matrix particles. Then, the particles are added to a low surface energy solution for chemical modification. Step 2: The material obtained in Step 1 is dispersed on the surface of the adhesive film, embedded in the adhesive film, and then cured to obtain a superhydrophobic coating material.

2. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, In step one, the etching time is 10-60 minutes. After etching, the sample is rinsed with deionized water and dried for later use.

3. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, The mass ratio of the metal-based particles, the volume of the mixed solution, and the volume ratio of the low surface energy solution are: (2-5) g : (94-125) mL : (12-20) mL.

4. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, The millimeter-sized metal powder particles in step one include at least one of millimeter-sized aluminum powder particles, millimeter-sized copper powder particles, and millimeter-sized zinc powder.

5. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, The low surface energy solution includes at least one of the following: a hexane solution containing trichloro-1H,2H,3H-heptadecylsilane, an ethanol solution containing palmitic acid, and an ethanol solution containing stearic acid.

6. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, In step one, the millimeter-sized metal powder particles are cleaned with deionized water and anhydrous ethanol, respectively, and then acid etched.

7. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, In step two, the adhesive film is obtained by mixing AB adhesive at a mass ratio of 1:1 and coating it with a thickness of 2mm to 3mm.

8. The method for preparing a superhydrophobic coating material according to claim 1, characterized in that, The mass ratio of the material to the adhesive film obtained in step one is (1.5-4):

1.

9. A superhydrophobic coating material, characterized in that, The superhydrophobic coating material is prepared by the preparation method described in any one of claims 1-8.

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