Super-hydrophobic anti-condensation coating based on self-jumping effect of condensation droplets and preparation method thereof

Abstract

The application discloses a super-hydrophobic anti-condensation coating based on a condensate droplet self-jumping effect and a preparation method thereof, relates to the technical field of anti-condensation coatings, and comprises the following formula: silicone resin, fluorocarbon resin, hydrophobic nano silicon powder, micron silicon powder, fluoroplastic micro powder, dilution solvent, dispersion aid, leveling aid, anti-sedimentation aid and curing agent, and is prepared based on the above formula. The application forms a micro-nano dual-stage rough structure, and utilizes the silicone resin and the fluorocarbon resin to form a stable embedded network, so that the coating presents extremely low adhesion and extremely low contact angle hysteresis in the initial nucleation and droplet growth stage of the condensate droplet, can make the tiny condensate droplet with a diameter of only 30-80 microns spontaneously jump off in the merging moment, significantly inhibits the formation of surface water and continuous water film, and fundamentally improves the anti-condensation capacity. The micro-nano particles are stably locked by the resin crosslinking network, and the structural stability and performance durability can still be maintained under long-term use conditions.

Description

Technical Field

[0001] This invention relates to the field of anti-condensation coating technology, specifically to a superhydrophobic anti-condensation coating based on the self-jumping effect of condensed droplets and its preparation method. Background Technology

[0002] In a condensation environment, water vapor in the air rapidly nucleates on the surface of a solid and forms tiny droplets. As the droplets grow, merge, and migrate in a directional manner, they easily form a continuous water film on the surface, which can cause problems such as obstructed field of view of optical components, reduced efficiency of heat exchange devices, and degraded insulation performance of electrical equipment.

[0003] To address these issues, existing technologies often employ superhydrophobic coatings to enhance the surface's ability to repel condensate, allowing water droplets to roll off or be carried away by airflow. However, traditional superhydrophobic coatings primarily rely on single-level microstructures or a single low-surface-energy material to construct high contact angle interfaces. When condensed droplets are at a small scale (20–80 μm), they often fail to achieve effective desorption. During nanoscale nucleation, droplets are easily "locked" by the structure, resulting in a high contact angle hysteresis and insufficient droplet coalescence. Ultimately, under continuous condensation conditions, phenomena such as water droplet retention, water retention, and water film formation still occur.

[0004] In addition, existing coatings generally suffer from insufficient microstructure durability and difficulty in stably constructing multi-level rough structures. When the coating is used in outdoor humid and hot cycling, low temperature condensation, or mechanical disturbance environments, micro and nano particles are prone to surface abrasion, structural collapse, or redistribution of surface energy, resulting in a rapid decline in their superhydrophobic and anti-condensation properties.

[0005] Especially for outdoor power grid equipment (such as insulators, switchgear, instrument transformers, terminal boxes, etc.), the operating environment is more severe. They not only endure long-term exposure to natural conditions such as large diurnal temperature variations, high humidity, salt spray, and ultraviolet radiation, but also face the effects of equipment vibration, corona discharge, and dirt accumulation. This places higher demands on anti-condensation coatings: they must not only achieve early self-jumping detachment of condensate droplets, but also possess excellent electrical insulation performance, long-term weather resistance, mechanical abrasion resistance, and strong adhesion to metal / ceramic substrates. Existing technologies commonly employ uniform hydrophobic modification methods for raw materials, which cannot simultaneously address multiple requirements such as micro / nano structure construction, interface compatibility control, electrical insulation assurance, and long-term durability. This leads to performance degradation and insulation failure of the coating under complex power grid conditions, making it difficult to meet the requirements for long-term safe and stable operation of power grid equipment.

[0006] Therefore, how to construct a micro-nano composite superhydrophobic interface that can trigger a "self-jumping effect" at the condensation droplet stage and maintain long-term stability under environmental cycling conditions is a key problem that has not yet been effectively solved by existing technologies. Summary of the Invention

[0007] This invention provides a superhydrophobic anti-condensation coating based on the self-jumping effect of condensed droplets and its preparation method, in order to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: One objective of this invention is to provide a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets and its preparation method, comprising the following raw materials in parts by weight: Organosilicon resin, 20–40 parts; fluorocarbon resin, 5–15 parts; hydrophobic nano-silica powder, 10–30 parts; micron-sized silica powder, 5–20 parts; fluoroplastic micro powder, 3–12 parts; diluent, 30–80 parts; dispersant, 1–5 parts; leveling agent, 0.5–3 parts; anti-settling agent, 0.5–3 parts; curing agent, 3–10 parts.

[0009] Furthermore, the hydrophobic nano-silica powder is prepared by performing low surface energy modification treatment on the nano-silica, including the following steps: Nano-silica was dissolved in anhydrous ethanol to obtain a dispersion. After stirring evenly, it was ultrasonically treated, an alkylsilane treatment agent was added, the pH value was adjusted, and after stirring and reacting, it was allowed to stand and settle, the supernatant was removed, dried, and then ground to obtain hydrophobic nano-silica powder.

[0010] This invention chooses deep modification with alkylsilanes instead of plasma modification or fluorosilane modification because: plasma-modified nano-silicon powder has poor hydrophobic stability and is prone to surface energy rebound under long-term humid and hot conditions in power grids; while fluorosilane modification can achieve lower surface energy, it is costly and introduces residual fluorine, which may affect the electrical insulation performance of the coating. In contrast, deep modification with alkylsilanes is cost-effective, reproducible, produces a Si-O-Si bond layer with excellent chemical stability that is not easily degraded in long-term outdoor environments, and the modified nano-silicon powder exhibits excellent electrical insulation properties, fully meeting the insulation requirements of power grid equipment.

[0011] The prepared hydrophobic nano-silicon powder exhibits a stable contact angle of over 140° and a tilt angle of less than 10° when tested with a 3μL water droplet. It can form a multi-level rough structure with micron-sized silicon powder, providing the necessary nanoscale basis for the spontaneous detachment and "self-jumping effect" of condensed droplets. This nano-silicon powder, processed using the above method, demonstrates highly controlled hydrophobicity, particle size stability, and dispersibility, ensuring strong repeatability and guaranteeing that the coating maintains low adhesion characteristics continuously in a condensation environment.

[0012] Furthermore, the average particle size of the nano-silica is 10-40 nm, and the specific surface area is 150-250 m² / g; Furthermore, the micron-sized silicon powder undergoes a mild hydrophobication treatment, comprising the following steps: Industrial-grade silicon powder is added to a ball mill, along with a surface lubricant and zirconia balls. The mixture is then ball-milled to stabilize the particle size from the original 10–20 μm to the 2–8 μm range. After ball milling, the larger portion of the particles is removed by sieving to obtain the ball-milled silicon powder. The ball-milled silicon powder was added to n-hexane and stirred to form a suspension. Methyltriethoxysilane was then added to react with the silane molecules to form a partially hydrophobic layer on the particle surface. Finally, the solid was filtered, dried, and ground to obtain slightly hydrophobic micron-sized silicon powder with a particle size of 2–8 μm.

[0013] This invention deliberately employs a mild, non-completely hydrophobic modification, rather than the conventional deep hydrophobic modification found in existing technologies. The core reason for this is that deep hydrophobization of micron-sized silicon powder would significantly reduce its interfacial bonding with organosilicon resin, leading to defects such as particle detachment and interfacial cracking in the coating, resulting in extremely poor durability under the vibration conditions of power grid equipment. Simultaneously, completely hydrophobic micron-sized particles would cause droplets to remain completely suspended on the surface, making it difficult to trigger vertical self-jumping due to the tendency for merging energy to dissipate horizontally. By controlling the amount of silane added and the reaction time, the surface energy of the micron-sized particles is reduced to the range of 30–45 mN / m. This ensures that the micron-sized structure can become a "desorption fulcrum" for droplets after the final coating film formation, guiding the vertical release of merging energy, while maintaining good compatibility with the resin system and improving the mechanical strength and long-term stability of the coating.

[0014] Micron-sized silica powder can form a functionally complementary composite rough structure on the coating surface, enabling early self-jumping of condensate at a particle size of 30–80 μm, effectively reducing the probability of condensation accumulation. This treatment method ensures that the micron-sized silica powder has both controllable particle size and maintains appropriate hydrophobicity, and is easy to repeat.

[0015] Furthermore, the preparation steps of the fluoroplastic micro powder include the following steps: The PTFE micro powder is obtained by dry mixing to achieve pre-homogenization, followed by air jet milling to reduce particle size and mild plasma activation treatment.

[0016] Furthermore, the air jet mill particle reduction treatment method is as follows: The pre-homogenized PTFE micro powder is fed into the feed hopper of the air jet mill. The parameters are adjusted to ensure that the powder enters the grinding chamber continuously and stably for particle reduction. The air jet mill adopts a jet-type or circulating structure with a nozzle orifice diameter of 0.8–1.2 mm. Compressed air or nitrogen is used as the working medium, and the working pressure is controlled at 0.6–0.8 MPa. After particle size reduction, a representative sample was taken and a laser particle size analyzer was used to detect the particle size under specified refractive index and shading conditions. It was confirmed that the particle size was concentrated in the range of 1–5 μm and the D50 was in the range of 2.5–3.5 μm.

[0017] Furthermore, the mild plasma activation treatment method is as follows: Weigh out the PTFE micro powder after it has been reduced in size by air jet milling, spread it evenly in a tray, and control the spreading thickness to 2–5 mm. Place the quartz tray containing the PTFE micro powder in the processing chamber of the radio frequency plasma processor for plasma treatment. The PTFE micro powder stays in the plasma sheath action area, and an activation layer with a very low thickness is formed on the surface under these conditions.

[0018] This invention chooses "air jet milling particle reduction + mild plasma activation" instead of directly using nano-PTFE powder or chemical grafting modification. Its core advantages are: nano-PTFE powder is prone to agglomeration, difficult to disperse uniformly in resin, and expensive; chemical grafting modification destroys the molecular structure of PTFE, leading to increased surface energy and loss of its low surface energy advantage. Air jet milling particle reduction can precisely control the PTFE particle size within 1–5 μm, while simultaneously forming micro-wrinkled morphology on the particle surface, increasing the mechanical interlocking force with the resin; mild plasma activation introduces only a very small amount of polar functional groups on the particle surface, solving the compatibility problem between PTFE and resin while fully preserving its ultra-low surface energy characteristics, and without introducing harmful impurities. This ensures the electrical insulation performance and anti-flashover capability of the coating, making it suitable for the operational requirements of outdoor power grid equipment.

[0019] Fluoroplastic micropowders, due to the weak physical intercalation between their activated surfaces and resin segments, and their unique micro-depression morphology, can be fixed at the bottom of steps and grooves in rough structures. Therefore, the coating maintains the stability of its lattice structure position even under thermal cycling, humid heat shock, and mechanical disturbances, without migration, detachment, or changes in energy distribution. This allows the self-jumping effect of condensed droplets to be maintained even after long-term use. Thus, by introducing fluoroplastic micropowders treated with this process, and synergistically interacting with the micro-nano composite rough structure, a ternary coupled interface structure, rarely seen in current superhydrophobic coating systems, is formed. This represents a significant technological advancement and demonstrates excellent performance in practical applications such as condensation suppression, anti-fogging, light transmission, and rapid surface drainage.

[0020] Furthermore, the silicone resin is methylphenyl silicone resin, used to construct the continuous phase film structure of the coating.

[0021] Further, the diluent is characterized in that the diluent is obtained by mixing xylene, butyl acetate and butanone in a mass ratio of 3:(1–2):(0.5–1).

[0022] The second objective of this invention is to provide a method for preparing a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets, comprising the following steps: S1. Add the silicone resin and fluorocarbon resin to the diluent and stir to fully dissolve the two resins and form a uniform resin mixture. S2. Add a dispersant to the resin mixture to form an interfacial adsorption layer in the system; S3. Hydrophobic nano-silicon powder, micron-sized silicon powder and fluoroplastic micro powder are added in sequence and dispersed by high-speed shearing to make the micro-nano particles evenly distributed in the resin and build a multi-level rough structure. S4. Add leveling agent and anti-settling agent, and stir to ensure stable distribution in the system; S5. Adjust the viscosity of the coating by diluting the solvent and add the curing agent to ensure uniform dispersion of the curing agent; S6. Apply the coating to the substrate and cure it to crosslink the resin and fix the micro-nano particle structure, forming a coating with superhydrophobic properties and the ability to self-jump of condensed droplets.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention constructs a micro-nano bilevel rough structure by combining hydrophobic nano-silica powder, micron-sized silica powder, and fluoroplastic micropowder. It utilizes a stable embedded network formed by organosilicon resin and fluorocarbon resin, enabling the coating to exhibit extremely low adhesion and contact angle hysteresis during the initial nucleation and growth stages of condensate droplets. This allows tiny condensate droplets with diameters of only 30–80 μm to spontaneously "jump away" upon merging, significantly inhibiting the formation of surface water and continuous water films, fundamentally improving anti-condensation capabilities. Simultaneously, the stable locking of micro-nano particles through the resin cross-linking network ensures the coating maintains structural stability and performance durability under conditions of humid heat cycling, low-temperature condensation, mechanical disturbance, and long-term outdoor use, achieving a higher level of anti-condensation, anti-fogging, and rapid drainage effects than existing technologies.

[0024] This invention addresses the different functions of hydrophobic nano-silicon powder, micron-sized silicon powder, and fluoroplastic micropowder in coatings by designing differentiated modification strategies: nano-silicon powder undergoes strong hydrophobic modification to achieve high grafting density and low adhesion interface; micron-sized silicon powder undergoes mild hydrophobic modification to balance hydrophobicity and resin bonding strength; and fluoroplastic micropowder undergoes a combination of air jet milling for particle reduction and plasma activation to balance low surface energy characteristics and interfacial compatibility. This differentiated modification design, tailored to the specific materials, enables the three types of particles to form a ternary coupled interface structure in the final coating with complementary functions and synergistic effects, overcoming the limitations of the "one-size-fits-all" modification in existing technologies.

[0025] In particular, this invention combines the aforementioned differentiated modification strategy with the specific requirements of power grid anti-condensation scenarios—power grid box-type equipment is spatially enclosed, and water droplets are not easily carried away by airflow, requiring extremely high early self-jumping capability of the coating; simultaneously, the equipment needs to withstand long-term outdoor humidity and heat, thermal cycling, and other environmental stresses, demanding stringent structural stability of the coating. The differentiated modification design of this invention precisely meets these two requirements: nanoscale strong hydrophobicity ensures that 30-40μm droplets can trigger self-jumping, micron-level mild hydrophobicity ensures a strong bond between particles and resin to resist long-term environmental stress, and plasma activation of fluoroplastic micropowder ensures the uniform distribution and long-term stability of low-energy micro-islands in the coating. Therefore, this invention is not only innovative in raw material selection and process parameters, but also represents a significant advancement and substantial feature in the "design concept of differentiated modification strategy" and "targeted optimization for power grid scenarios." Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process for preparing a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets proposed in this invention. Detailed Implementation

[0027] The present invention will be further described below with reference to preferred embodiments and the accompanying drawings. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges. These numerical ranges should be considered as specifically disclosed herein. Unless otherwise specified, all materials and reagents used in the following examples are commercially available; and all experimental methods used in the following examples are conventional methods unless otherwise specified.

[0028] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0029] This invention addresses the structural characteristics and roles of different functional components in the coating system, and combines this with the specific operating requirements of power grid equipment for condensation prevention. It employs a differentiated and precise surface modification strategy, rather than the uniform hydrophobic modification commonly used in existing technologies. Its core principles are as follows: 1. Hydrophobic Nano-Silica Powder: Employing an "ultrasonic dispersion + deep hydrophobic modification with alkyl silanes" process. The core function of the nano-silica powder is to construct a nanoscale rough structure, providing initial Cassie-Baxter support for condensed droplets. Due to the large number of hydroxyl groups on the surface of nano-silica, hydrogen bonding aggregation is highly likely. Insufficient modification can lead to inhomogeneous nanostructures, thus affecting the triggering of the self-jumping effect. Therefore, this invention breaks down agglomerates through ultrasonic pretreatment, followed by deep modification with alkyl silanes under acidic conditions. This forms a dense Si-O-Si bonded hydrophobic layer on the particle surface, ensuring both the dispersibility of the nanoparticles and reducing their surface energy to below 25 mN / m, meeting the low adhesion requirements of the nanoscale rough structure. Simultaneously, the deeply modified nano-silica powder exhibits excellent electrical insulation properties without reducing the breakdown strength of the coating, making it suitable for the insulation requirements of power grid equipment.

[0030] 2. Micron-sized silicon powder: A composite modification process of "planetary ball milling particle size control + mild hydrophobication with methyltriethoxysilane" is employed. The core function of micron-sized silicon powder is to construct a micron-level stepped structure, providing mechanical support for droplet coalescence and improving energy release efficiency. Existing technologies for micron-sized silicon powder often involve directly purchasing finished products or performing simple, deep hydrophobic modification, resulting in problems such as wide particle size distribution, insufficient morphological irregularity, and poor resin compatibility. This invention first uses a planetary ball milling process with sodium stearate as a surface lubricant to precisely control the particle size within the 2–8 μm range, simultaneously obtaining an approximately irregular blocky morphology, significantly improving the roughness of the micron structure and droplet support capacity; subsequently, a mild hydrophobication treatment is applied, reducing the particle surface energy to the 30–45 mN / m range, rather than pursuing complete hydrophobicity. The core advantages of this design are: ① Slight hydrophobicity avoids interface defects caused by poor compatibility between micronized silica powder and silicone resin system, ensuring the adhesion and mechanical strength of the coating; ② Moderate surface energy allows micronized particles to become droplet "desorption fulcrums" rather than completely repelling droplets, thereby guiding the energy of droplet merging to be released in a direction perpendicular to the surface, significantly improving the self-jumping height and detachment efficiency; ③ The sodium stearate residue introduced during the ball milling process can further improve the lubricity and wear resistance of the coating, making it suitable for the long-term vibration and dirt wear conditions of power grid equipment.

[0031] 3. Fluoroplastic micropowder: Modified using an "air jet milling particle reduction + mild plasma activation" process. The core function of fluoroplastic micropowder is to construct dispersed low surface energy "micro-islands" to further reduce droplet adhesion. PTFE itself has extremely low surface energy, but its compatibility with organosilicon resins is extremely poor. Direct addition can easily lead to problems such as agglomeration and delamination, and it is difficult to distribute evenly in the gaps between micro and nano structures. This invention controls the PTFE particle size to 1–5 μm through air jet milling particle reduction, while forming a micro-wrinkled morphology on the particle surface, increasing the specific surface area and mechanical interlocking force. Then, mild plasma activation introduces a very small number of polar functional groups into the surface layer, significantly improving the interfacial compatibility with the resin system without destroying its low surface energy characteristics. This allows it to be uniformly embedded in the potential well region of the micro and nano structures, forming a "discrete low-energy lattice". This structure not only reduces droplet adhesion energy but also avoids the problems of easy contamination and decreased insulation performance of overall low surface energy coatings, meeting the anti-flashover and insulation requirements of power grid equipment.

[0032] Example 1 This embodiment provides a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets, with the following formulation: silicone resin, 20 parts; fluorocarbon resin, 5 parts; hydrophobic nano-silica powder, 10 parts; micron-sized silica powder, 5 parts; fluoroplastic micro powder, 3 parts; diluent, 80 parts; dispersant, 1 part; leveling agent, 0.5 parts; anti-settling agent, 0.5 parts; curing agent, 3 parts.

[0033] The preparation method of the superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets specifically includes the following steps: S1. Add the silicone resin and fluorocarbon resin to the pre-prepared diluent system, turn on the mechanical stirrer, and stir at 500 rpm for 30 minutes to fully wet and mix the silicone resin and fluorocarbon resin in the diluent to form a uniform and transparent resin mixture.

[0034] S2. After the resin mixture is formed, add the dispersing agent to the system and continue stirring at 600 rpm for 20 minutes to make the dispersing agent evenly distributed in the resin system and form an interfacial structure that can coat the surface of the powder.

[0035] S3. After the resin-dispersant system is formed, hydrophobic nano-silica powder, micron-sized silica powder, and fluoroplastic micro powder are added sequentially. After addition, the mixture is stirred at a low speed of 500 rpm for 15 minutes to initially wet the powder in the system. Then, a high-speed disperser is used for shearing treatment at a shearing speed of 9000 rpm for 5 minutes to fully disperse the three types of powder in the resin medium and construct the basic distribution state of the micro-nano composite rough structure.

[0036] S4. After the powder is completely dispersed, add leveling agent and anti-settling agent to the system. After adding the above agents, stir the system at 700 rpm for 30 min to make the leveling agent uniformly dispersed in the resin phase and the anti-settling agent constructing a preliminary three-dimensional network structure in the system, thereby effectively limiting the sedimentation tendency of hydrophobic nano-silica powder, micron-silica powder and fluoroplastic powder during storage.

[0037] S5. Based on the final construction method, adjust the system viscosity to 150–300 mPa·s (25℃) by adding diluent. After viscosity adjustment, add the curing agent to the system and stir at 500 rpm for 20 min to ensure uniform dispersion of the curing agent in the resin phase. During the subsequent thermosetting process, the curing agent will undergo a cross-linking reaction with the silicone resin and fluorocarbon resin, allowing micronized silica powder, hydrophobic nano-silica powder, and fluoroplastic micropowder to be stably embedded in the three-dimensional network structure of the resin.

[0038] S6. Apply the above mixed coating evenly to the surface of the substrate to be treated, and control the coating thickness to be 15–40 μm. After coating, place the substrate in an environment of 150°C for 40 min to cure, so that the resin system cross-links and cures and fixes the powder structure, forming a multi-level rough interface composed of hydrophobic nano-silica powder, micron-sized silica powder and fluoroplastic micro powder.

[0039] The hydrophobic nano-silicon powder is selected from nano-silica with an average particle size of 10–40 nm and a specific surface area of ​​150–250 m² / g as the substrate; the hydrophobic nano-silicon powder is made by modifying nano-silica with low surface energy through surface hydrophobic treatment, so that it forms a synergistic rough structure with micron-sized silicon powder in the coating.

[0040] Furthermore, the low surface energy modification method includes: 200g of anhydrous ethanol was added to a 500mL three-necked flask as a dispersion medium, and 50g of nano-silica was slowly added. The mixture was magnetically stirred at 500rpm for 30min to form a homogeneous slurry. The slurry was then treated with an ultrasonic disperser at 300W for 20min to break the hydrogen bond agglomeration between silica particles. After the dispersion stabilized, 6g of alkylsilane treatment agent was added, and the pH of the system was controlled at 4.0–5.5 to facilitate the silane hydrolysis and condensation reaction. The mixture was stirred at 60℃ for 3h to form a dense Si-O-Si bond layer on the silica surface, and the surface alkyl chains were synchronously arranged to form a low surface energy film layer. After the reaction, the mixture was allowed to settle, the supernatant was discarded, and the solid was dried in an oven at 90℃ for 6h. Finally, it was lightly ground through a 120-mesh sieve to obtain the modified hydrophobic nano-silica powder.

[0041] The micron-sized silicon powder uses industrial-grade silicon powder as the substrate, with a particle size controlled between 2 and 8 μm and an approximately irregular block shape, which is used to form a synergistic rough structure of micro-nano bi-level with hydrophobic nano-silicon powder. Industrial-grade silicon powder was added to a planetary ball mill, along with 0.6 wt% sodium stearate as a surface lubricant, and then 8 times the mass ratio of zirconia balls were added. The mill was then run at 250 rpm for 2.5 hours to stabilize the particle size from the original 10–20 μm to the 2–8 μm range. After milling, the particles were sieved through a 150-mesh sieve to remove the larger particles. After a slight hydrophobic treatment, micron-sized silicon powder was obtained.

[0042] The mild hydrophobication treatment specifically includes the following steps: Add 100g of ball-milled silicon powder to 250mL of n-hexane and stir at 300rpm for 15min to form a suspension. Then add 3g of methyltriethoxysilane and let it react at room temperature for 2h to form a hydrophobic layer on the particle surface with silane molecules. Finally, filter the solid, dry it and grind it lightly to obtain slightly hydrophobic micronized silicon powder.

[0043] The fluoroplastic micro powder is made of PTFE micro powder, and the preparation process is "air jet milling particle reduction + mild plasma activation", the specific steps of which are as follows: Add 80g of PTFE micro powder to a 1000mL stainless steel mixing jar and dry mix at 800rpm for 15min to pre-homogenize the particles; use an air jet mill to perform secondary particle reduction on the powder under a nozzle pressure of 0.8MPa, so that the final particle size is concentrated in the range of 1–5μm, and confirm that its D50 is within 2.5–3.5μm by a laser particle size analyzer. Fluoroplastic micro powder was obtained by mild plasma surface activation treatment followed by sealed storage of the powder.

[0044] The specific steps for particle reduction in air jet milling are as follows: PTFE micro powder is fed into the feed hopper of the air classifier mill through a closed conveying device. The feed hopper is equipped with a screw quantitative feeder with a feeding speed set at 2.0 kg / h, so that the powder can continuously and stably enter the mill chamber for particle reduction. The air classifier mill adopts a spray or circulation structure with a nozzle orifice diameter of 1.2 mm. Compressed air or nitrogen is used as the working medium, and the working pressure is controlled at 0.8 MPa. After particle reduction is completed, a representative sample is taken and the particle size is measured using a laser particle size analyzer under specified refractive index and shading conditions. If the particle size distribution deviates from the range, it is corrected by adjusting the nozzle pressure, feeding speed or repeating the particle reduction steps.

[0045] The specific steps of the above-mentioned mild plasma surface activation treatment are as follows: 50g of fluoroplastic micro powder, after secondary particle reduction, was spread in a quartz tray and placed in an RF plasma processor. The RF power was set to 120W and the processing time to 90s, so that a small number of polar functional groups were generated on the surface of the PTFE micro powder.

[0046] The organosilicon resin used is methylphenyl silicone resin, which is used to construct the continuous phase film structure of the coating. The preparation process includes: Add 250g xylene as solvent to a 500mL reaction vessel and stir at 80℃ for 20min to stabilize the system; Add 180g of methylphenyl silicone resin pre-solution with a solid content of 60%, and continue stirring until the system is clear and transparent; Add 3 wt% silane coupling agent and react at 90°C for 45 min to allow the coupling agent to form a stable interfacial bridging structure between the resin and particles, thus obtaining an organosilicon resin for constructing a continuous phase film structure for coating.

[0047] The diluent is obtained by mixing xylene, butyl acetate and butanone in a mass ratio of 3:2:1.

[0048] Among them, fluorocarbon resin is fluorocarbon acrylic resin.

[0049] The dispersing agent is a polyester-type dispersant.

[0050] The leveling agent is an organosilicon leveling agent.

[0051] Among them, the anti-settling agent selected is organic bentonite anti-settling agent.

[0052] The curing agent used is bis(diisopropylbenzene) peroxide curing agent.

[0053] Example 2 This embodiment provides a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets, with the following formulation: silicone resin, 30 parts; fluorocarbon resin, 10 parts; hydrophobic nano-silica powder, 20 parts; micron-sized silica powder, 12 parts; fluoroplastic micro powder, 7 parts; diluent, 55 parts; dispersant, 3 parts; leveling agent, 1.5 parts; anti-settling agent, 1.5 parts; curing agent, 6 parts.

[0054] The diluent is obtained by mixing xylene, butyl acetate and butanone in a mass ratio of 3:1:0.5.

[0055] Except for the different formulations, the preparation methods of the coatings and raw materials are the same as in Example 1.

[0056] Example 3 This embodiment provides a superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets, with the following formulation: silicone resin, 40 parts; fluorocarbon resin, 15 parts; hydrophobic nano-silica powder, 30 parts; micron-sized silica powder, 20 parts; fluoroplastic micro powder, 12 parts; diluent, 30 parts; dispersant, 5 parts; leveling agent, 3 parts; anti-settling agent, 3 parts; curing agent, 10 parts.

[0057] Except for the different formulations, the preparation methods of the coatings and raw materials are the same as in Example 1.

[0058] Comparative Example 1 The superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets provided in this embodiment has the following formulation: 30 parts of silicone resin; 10 parts of fluorocarbon resin; 22 parts of hydrophobic nano-silica powder; 7 parts of fluoroplastic micro powder; 55 parts of diluent; 3 parts of dispersant; 1.5 parts of leveling agent; 1.5 parts of anti-settling agent; and 6 parts of curing agent.

[0059] The only difference between this embodiment and Embodiment 1 is that it does not contain micron-sized silicon powder and only contains a single-level rough structure. Its preparation method is the same as that of Embodiment 1.

[0060] Comparative Example 2 The superhydrophobic anti-condensation coating based on the self-jumping effect of condensation droplets provided in this embodiment has the following formulation: 30 parts of silicone resin; 10 parts of fluorocarbon resin; 20 parts of hydrophobic nano-silica powder; 12 parts of micron-sized silica powder; 55 parts of diluent; 3 parts of dispersant; 1.5 parts of leveling agent; 1.5 parts of anti-settling agent; and 6 parts of curing agent.

[0061] The only difference between this embodiment and Example 1 is that it does not contain fluoroplastic micropowder, only low-energy resin, and does not contain low-energy micro-islands; the rest of the preparation methods are the same as in Example 1.

[0062] Performance testing The coatings obtained in the above embodiments and comparative examples were subjected to the following tests: 1. Static water contact angle test The prepared coating samples were placed in a laboratory environment with a constant temperature (25±2℃) and relative humidity of 40%~60% for 24 hours to equilibrate. Using a contact angle meter (using the sitting drop method), a 3μL drop of deionized water was slowly added to the coating surface. After the droplet stabilized, the contact angle value was recorded. At least 5 different locations were selected for testing for each sample, and the average value of the test results was taken as the static water contact angle of the sample.

[0063] 2. Sliding angle test Under the same environmental conditions as the static water contact angle, the sample was fixed on an adjustable tilt platform. A 5 μL droplet of deionized water was dropped onto the coating surface. While maintaining the stability of the droplet shape, the tilt angle of the platform was slowly increased at a rate of 1° / s. The tilt angle at which the droplet began to slide continuously along the surface was recorded as the sliding angle of the sample. The same sample was tested at least 5 times, and the average value was taken.

[0064] 3. Test of residual water area on surface after condensation for 5 minutes The coated sample was placed in a constant temperature and humidity condensation test chamber. The ambient temperature was set to 5±1℃, the relative humidity to be above 90%, and a temperature difference of 25±2℃ was maintained between the back of the sample and the outside air to create condensation conditions. After condensation for 5 minutes, the sample was removed, and the sample surface was immediately photographed using a high-definition camera at a fixed distance and under fixed lighting conditions. The projected area of ​​the surface covered by water droplets or water film was statistically analyzed using image analysis software and divided by the total surface area of ​​the sample to obtain the percentage of "surface residual water area after 5 minutes of condensation". The smaller the value, the better the drainage and anti-condensation ability.

[0065] 4. Test of the initial diameter of condensate droplets upon self-jumping A cold-stage microscopy system was used. The coating sample was placed on a temperature-controlled cold stage with a temperature set between 0 and 5°C and an ambient relative humidity maintained between 80% and 95%. The nucleation, growth, and merging behavior of droplets during condensation were observed in real time using a microscope. As the condensation time increased, the moment when the droplet was first observed to spontaneously jump off the coating surface and completely detach from it after merging was recorded. The equivalent diameter of the droplet before jumping at that instant was measured, and the initial droplet diameter of at least 20 self-jumping events was recorded. The average value was taken as the "initial diameter of condensed droplet self-jumping". The smaller this index, the more likely the coating can trigger the self-jumping effect in the early stages of condensation.

[0066] 5. Anti-fog time test (constant temperature and humidity chamber) A sample with a coating on the surface of a transparent substrate (glass slide) was mounted on a simulated window device. One side was exposed to a constant temperature and humidity condensation environment (5±1℃, relative humidity above 90%), while the other side faced the indoor side. An optical target or standard vision chart was used as a background reference. The condensation condition timer was started. When significant fogging was observed on the glass surface, causing the clarity of the background marker to decrease to a preset standard (e.g., contrast reduced to 50% of the initial value), the corresponding time was recorded as the "anti-fog time" for that sample. The test was repeated three times for each sample, and the average value was taken. The longer the anti-fog time, the stronger the coating's ability to inhibit condensate from accumulating into fog.

[0067] 6. Contact angle retention test after 200 cycles of hot and cold cycling After preparing the coating samples according to the specified process, their initial static water contact angle was first tested. The samples were then placed in a thermal cycling test chamber for cyclic testing, with each cycle including: a low-temperature phase (…). The process involved two phases: a 20±2℃, 30 min high-temperature and high-humidity phase (60±2℃, relative humidity above 90%, 30 min), with a 10 min transition time between the two phases. After 200 cycles, the sample was allowed to equilibrate to room temperature for 2 h, and the static water contact angle was measured again using the aforementioned method to obtain the contact angle retention rate, which was used to evaluate the stability of the coating's superhydrophobic properties under thermal cycling stress.

[0068] 7. Adhesion test (cross-cut test) The coating adhesion was tested using a standard cross-cut test method. A cross-cutting tool with a multi-bladed blade was used to cut a regular grid pattern into the coating surface, extending to the substrate. Special adhesive tape was then applied to the grid area, pressed firmly under specified pressure, and then quickly peeled off at a fixed angle and speed. The extent of coating peeling within the grid was observed, and the adhesion grade was determined based on the percentage of coating residue in each grid (e.g., grade 0 indicates no peeling, grade 1 indicates slight peeling, etc.). A lower adhesion grade indicates better adhesion.

[0069] 8. Pencil Hardness Test The scratch resistance of the coating surface was evaluated according to the standard pencil hardness test method. Pencils of different hardness grades from 6B to 6H were selected. The pencil leads were shaved flat and ground on sandpaper to create a surface, ensuring a certain contact area between the lead and the coating surface. At an angle of 45° or 90°, a load of approximately 750g (or the standard required load) was applied along the coating surface for a certain distance, and the appearance of obvious scratches or exposure of the underlying material was observed. The highest pencil hardness grade that did not cause visible scratches was used as the "pencil hardness" index of the sample, characterizing the surface mechanical strength and abrasion resistance of the coating.

[0070] The test results are shown in Table 1: Table 1. Performance test results of coatings obtained in Examples 1-3 and Comparative Examples 1-2

[0071] As can be seen from the test results in Table 1, the superhydrophobic anti-condensation coatings prepared in Examples 1-3 are significantly superior to Comparative Examples 1 and 2 in key indicators such as static water contact angle, sliding angle, self-jumping initiation diameter of condensate droplets, and anti-fogging time. Specifically, Examples 2 and 3, through the reasonable ratio and synergistic distribution of hydrophobic nano-silica powder, micron-silica powder, and fluoroplastic micropowder in the silicone resin and fluorocarbon resin matrix, formed a stable micro-nano composite rough structure and a low surface energy micro-island structure on the coating surface. Its static water contact angle can be stabilized above 160°, the sliding angle is controlled at 3-4°, the self-jumping initiation diameter of condensate droplets can be reduced to 35-45 μm, and the surface residual water area is reduced to 5-8% after condensation for 5 minutes. This indicates that the small droplets formed during the condensation process can self-jump and detach at a small volume stage, effectively suppressing water film formation and fogging. In contrast, Comparative Example 1 eliminated micron-sized silicon powder and relied solely on hydrophobic nano-sized silicon powder to construct a single-level rough structure. Although it still possessed some hydrophobicity, the sliding angle significantly increased, and the self-jumping initiation diameter of the condensate droplets increased to 85 μm. After 5 minutes of condensation, the surface residual water area reached 28%, indicating that the lack of a micron-level stepped structure makes it difficult to trigger efficient self-jumping behavior. Comparative Example 2, without fluoroplastic microparticles, relied solely on fluorocarbon resin to provide low surface energy. Its contact angle was slightly improved, but the sliding angle remained relatively large. The self-jumping initiation diameter of the condensate droplets was approximately 80 μm, and the anti-fogging time was significantly shorter than that of Examples 2 and 3. This indicates that the lack of dispersed low-surface-energy micro-island structures leads to higher adhesion between the condensate and the substrate, limiting self-jumping behavior. Furthermore, after 200 cycles of thermal cycling, the contact angle retention rate of Examples 1-3 remained in the range of 92-96%, and the adhesion was all at level 0. This indicates that the cross-linked network constructed by the silicone resin and fluorocarbon resin can effectively lock the spatial positions of the hydrophobic nano-sized silicon powder, micron-sized silicon powder, and fluoroplastic microparticles, resulting in a stable coating structure and good durability. In summary, the three embodiments exhibit significantly better overall performance than the comparative example in terms of superhydrophobicity, anti-condensation properties, and environmental durability, fully verifying the technical advantages of the formulation and micro / nano structure design in achieving the self-jumping effect of condensate droplets and long-term anti-condensation effect.

[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets, characterized in that, Includes the following quantities of raw materials: Organosilicon resin, 20–40 parts; fluorocarbon resin, 5–15 parts; hydrophobic nano-silica powder, 10–30 parts; micron-sized silica powder, 5–20 parts; fluoroplastic micro powder, 3–12 parts; diluent, 30–80 parts; dispersant, 1–5 parts; leveling agent, 0.5–3 parts; anti-settling agent, 0.5–3 parts; curing agent, 3–10 parts.

2. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 1, characterized in that, The hydrophobic nano-silica powder is prepared by performing low surface energy modification treatment on nano-silica, including the following steps: Nano-silica was dissolved in anhydrous ethanol to obtain a dispersion. After stirring evenly, it was ultrasonically treated, an alkylsilane treatment agent was added, the pH value was adjusted, and after stirring and reacting, it was allowed to stand and settle, the supernatant was removed, dried, and then ground to obtain hydrophobic nano-silica powder.

3. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 2, characterized in that, The nano-silica has an average particle size of 10-40 nm and a specific surface area of ​​150-250 m². 2 / g.

4. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 1, characterized in that, The micron-sized silicon powder undergoes a mild hydrophobication treatment, comprising the following steps: Industrial-grade silicon powder is added to a ball mill along with a surface lubricant and then zirconia balls. The mixture is then ball-milled to stabilize the particle size from the original 10–20 μm to the 2–8 μm range. After ball milling, the larger portion of the particles is removed by sieving to obtain the ball-milled silicon powder. The ball-milled silicon powder was added to n-hexane and stirred to form a suspension. Methyltriethoxysilane was then added to react with the silane molecules to form a partially hydrophobic layer on the particle surface. Finally, the solid was filtered, dried, and ground to obtain slightly hydrophobic micron-sized silicon powder with a particle size of 2–8 μm.

5. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 1, characterized in that, The preparation of the fluoroplastic micro powder includes the following steps: The PTFE micro powder is obtained by dry mixing to achieve pre-homogenization, followed by air jet milling to reduce particle size and mild plasma activation treatment.

6. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 5, characterized in that, The air jet milling particle reduction method is as follows: The pre-homogenized PTFE micro powder is fed into the feed hopper of the air jet mill. The parameters are adjusted to ensure that the powder enters the grinding chamber continuously and stably for particle reduction. The air jet mill adopts a jet-type or circulating structure with a nozzle orifice diameter of 0.8–1.2 mm. Compressed air or nitrogen is used as the working medium, and the working pressure is controlled at 0.6–0.8 MPa. After particle size reduction, a representative sample was taken and a laser particle size analyzer was used to detect the particle size under specified refractive index and shading conditions. It was confirmed that the particle size was concentrated in the range of 1–5 μm and the D50 was in the range of 2.5–3.5 μm.

7. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 5, characterized in that, The mild plasma activation treatment method is as follows: Weigh out the PTFE micro powder after it has been reduced in size by air jet milling, spread it evenly in a tray, and control the spreading thickness to 2–5 mm. Place the tray containing the PTFE micro powder in the processing chamber of the radio frequency plasma processor for plasma treatment. The PTFE micro powder stays in the plasma sheath area and forms an activation layer with a very low thickness on the surface.

8. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 1, characterized in that, The silicone resin used is methylphenyl silicone resin, which is used to construct the continuous phase film structure of the coating.

9. The superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets according to claim 1, characterized in that, The diluent is a mixture of xylene, butyl acetate and butanone in a mass ratio of 3:(1–2):(0.5–1).

10. A method for preparing a superhydrophobic anti-condensation coating based on the self-jumping effect of condensate droplets as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Add the silicone resin and fluorocarbon resin to the diluent and stir to fully dissolve the two resins and form a uniform resin mixture. S2. Add a dispersant to the resin mixture to form an interfacial adsorption layer in the system; S3. Hydrophobic nano-silicon powder, micron-sized silicon powder and fluoroplastic micro powder are added in sequence and dispersed by high-speed shearing to make the micro-nano particles evenly distributed in the resin and build a multi-level rough structure. S4. Add leveling agent and anti-settling agent, and stir to ensure stable distribution in the system; S5. Adjust the viscosity of the coating by diluting the solvent and add the curing agent to ensure uniform dispersion of the curing agent; S6. Apply the coating to the substrate and cure it to crosslink the resin and fix the micro-nano particle structure, forming a coating with superhydrophobic properties and the ability to self-jump of condensed droplets.

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