Hollow glass / TiO2 super-hydrophobic radiation cooling coating, method and application of hollow glass / TiO2 super-hydrophobic radiation cooling coating

Abstract

The invention belongs to the field of new materials, and particularly relates to a hollow glass / TiO2 super-hydrophobic radiation cooling coating, a method and application thereof. The preparation method comprises the following steps: modifying hollow glass microspheres (GB) by using triethoxy-1H, 1H, 2H, 2H-tridecafluoro-N-octylsilane (PFOTES) to obtain F-GB particles with low surface energy and high reflectivity, then adding TiO2, taking epoxy resin E51 and a silane coupling agent KH550 as adhesives, carrying out uniform spraying operation, drying, and repeating the operation once to obtain the coating with high reflectivity. The coating has a water contact angle of 154 degrees, and has excellent cleaning capability on liquid and solid pollutants on the surface of the coating. And meanwhile, the coating has the highest sunlight reflectivity of 92.5% and high infrared emissivity, can realize the cooling effect of about 14 DEG C, and has excellent radiation cooling performance. And the coating can still keep the self-cleaning capability and the radiation cooling capability after 120 times of wear cycles.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and specifically relates to a hollow glass / TiO2 superhydrophobic radiation cooling coating, its method, and its application. Background Technology

[0002] In recent years, with the increasing severity of global warming and energy shortages, there is an urgent need for passive cooling technologies that achieve cooling without consuming energy. All-day passive radiative cooling (PDRC) technology reflects sunlight within a wavelength range of 0.3-2.5 μm while simultaneously emitting heat into the cold outer space through atmospheric transparency windows between 8-13 μm, thus achieving cooling without any energy consumption or pollutant generation. Compared to traditional cooling technologies, PDRC reduces greenhouse gas emissions and saves energy, making it a promising solution for energy utilization and environmental protection. There are many methods for preparing radiative cooling materials, such as spraying, phase separation, and electrospinning. The selection of a preparation method requires comprehensive consideration of the material's optical properties, processing performance, and application scenarios. Due to the uniform thickness, simple process, low cost, and ease of expansion of radiative cooling coatings prepared by spraying, it has received widespread attention in industrial production.

[0003] One study selected n-octadecane phase change material as the core material and used Pickering emulsion polymerization to prepare MZZS-PMMA phase change microcapsules by grafting polyacrylic acid with ZnO@ZIF-8@SiO2 (MZZS) nanoparticles, which possess radiative cooling properties, as a stabilizer. These microcapsules were then applied to fabric finishing. The MZZS-PMMA phase change microcapsule-coated fabric exhibited certain radiative cooling and temperature regulation effects, achieving temperatures close to 9°C. oThe cooling effect of C. However, the fabric is easily contaminated, which leads to a decrease in its radiative cooling capacity. Jiang et al. used anhydrous magnesium chloride as the magnesium source, sodium pyrophosphate as the phosphorus source, and zinc oxide as the zinc source to synthesize ZnO-doped MgHPO4·0.78H2O powder using a two-step hydrothermal synthesis method. Then, using polyvinyl alcohol (PVA) as a film-forming agent, a radiative cooling coating of ZnO-doped MgHPO4·0.78H2O was prepared, and the daytime radiative cooling performance of the coating was studied. The results showed that the powder with a Mg:P:ZnO molar ratio of 1∶1∶0.5 had an average solar spectrum reflectance of up to 93% and an average emissivity of 91% in the atmospheric window (8-13μm). Compared with the undoped ZnO MgHPO4·0.78H2O powder, the solar spectrum reflectance (0.3~2.5μm) was increased by 3%, and the near-infrared reflectance was increased by 7%. The coating can achieve daytime radiative cooling 3℃ lower than the ambient air temperature in high humidity areas. However, the article did not describe the mechanical properties of the coating. The adhesion between the coating and the substrate, as well as its wear resistance, are also important factors limiting the large-scale application of radiation cooling coatings in industrial production.

[0004] To address the practical application of radiation cooling coatings on building surfaces and prevent the coating's radiation cooling capacity from decreasing due to various forms of contamination, developing a self-cleaning radiation cooling coating is of significant importance. This invention uses triethoxy-1H,1H,2H,2H-tertetrafluoro-N-octylsilane (PFOTES) to modify hollow glass microspheres (GB), then mixes them with TiO2, adds epoxy resin E51 as a binder, and uses silane coupling agent KH55O as both a curing agent for E51 and an agent to improve the adhesion strength between the coating and the substrate. A radiation cooling coating with superhydrophobic properties is prepared using a spraying method. The coating has a viscosity of 154... o With a water contact angle of up to 14°, it achieves a superhydrophobic effect, exhibiting excellent cleaning ability for liquid and solid contaminants on the coating surface. Simultaneously, the coating possesses a maximum solar reflectivity of 92.5% and high infrared emissivity, enabling it to achieve 14... o The coating exhibits a cooling effect of around °C, demonstrating excellent radiative cooling performance. Even after 120 wear cycles, the coating retains its self-cleaning and radiative cooling capabilities. This invention not only provides a method for preparing superhydrophobic radiative cooling coatings but also lays a foundation for their practical applications. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a hollow glass / TiO2 superhydrophobic radiation cooling coating, a method thereof, and its application.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a hollow glass / TiO2 superhydrophobic radiation cooling coating, the coating comprising TiO2 and F-GB obtained by PFOTES-modified hollow glass microspheres GB in a mass ratio of 2:3 and a molar ratio of E51:KH550 in a molar ratio of 1:2, wherein the total amount of particles to the amount of KH550-modified E51 is 5:2.

[0007] Furthermore, the superhydrophobic radiation cooling coating exhibits a water contact angle of 154° and an adhesion strength of 1.417 MPa to the substrate. Even after 120 wear tests, it maintains a hydrophobic effect with a contact angle of 140°. The superhydrophobic radiation cooling coating can achieve a water contact angle of 600 W / m. 2 It achieves a cooling effect of 14°C under solar radiation intensity.

[0008] Secondly, the present invention provides a method for preparing a hollow glass / TiO2 superhydrophobic radiation cooling coating, comprising the following steps: Step 1: Preparation of Fluorinated Hollow Glass Microspheres GB was dispersed in anhydrous ethanol, PFOTES was added, and the pH was adjusted to 7-8 with ammonia. The mixture was then heated in a water bath for 50-70 degrees Celsius. o C, after 2-3 hours, open the stopper and continue for 50-70 minutes. o Heat at C for 10-20 min to remove ammonia water, and obtain PFOTES modified fluorinated hollow glass F-GB solution; Step 2: Preparation of superhydrophobic radiation cooling coating Add TiO2 to the F-GB solution prepared in step one, then add epoxy resin E51 and silane coupling agent KH550, totaling 1.8~2.2 g, and 50~70 g. o Heating in a water bath at C for 2 hours yields a precursor solution. Add 5-10 ml of this solution to the spraying apparatus, maintaining a distance of 15-20 cm between the spray gun and the substrate. Perform uniform spraying and place the mixture in a 50-70 mL container. o After baking in an oven at C for 3-5 minutes, repeat the above steps once to obtain the coating.

[0009] Furthermore, in step one, the amount of GB used is 2.8~3.2 g, and the amount of anhydrous ethanol used is 12~20 ml.

[0010] Furthermore, in step one, the mass ratio of GB to PFOTES is (14~16):1.

[0011] Furthermore, in step two, the amount of TiO2 used is 1.8~2.2 g.

[0012] Furthermore, in step two, the molar ratio of epoxy resin E51 and silane coupling agent KH550 is 1:(1.8~2.2).

[0013] Furthermore, the mass ratio of GB, TiO2 and silane coupling agent KH550 modified epoxy resin E51 is (2.8~3.2): (1.8~2.2): (1.8~2.2).

[0014] Thirdly, the present invention provides the application of hollow glass / TiO2 superhydrophobic radiation cooling coating in building materials or various substrates.

[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention uses triethoxy-1H,1H,2H,2H-tridecylfluoro-N-octylsilane (PFOTES) to modify hollow glass microspheres (GB) to obtain F-GB particles with low surface energy and high reflectivity. TiO2 is then added, and epoxy resin E51 and silane coupling agent KH550 are used as binders for uniform spraying. After drying, the above operation is repeated once to obtain a coating with high reflectivity. The coating has a surface energy of 154... o With a water contact angle of up to 92.5%, the coating exhibits excellent cleaning capabilities against both liquid and solid contaminants on its surface. Simultaneously, the coating possesses a high solar reflectivity of 92.5% and high infrared emissivity, enabling it to achieve 14... o It provides a cooling effect of around 1°C and exhibits excellent radiative cooling performance. The coating retains its self-cleaning and radiative cooling capabilities even after 120 wear cycles. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 is a schematic diagram of the preparation of the superhydrophobic radiation cooling coating; Figure 2 shows the SEM and EDS images of GB modified by PFOTES on hollow glass microspheres and GB and F-GB. Figure 3 shows the contact angles of coatings prepared with different amounts of PFOTES added by F-GB; Figure 4. Effect of different particle amounts on coating reflectivity and water contact angle; Figure 5 shows the effect of different particle ratios on coating reflectivity and water contact angle; Figure 6 shows the effect of the ratio of epoxy resin E51 to KH550 on the coating adhesion. Figure 7 shows a SEM image of the superhydrophobic radiation cooling coating; Figure 8 shows the SEM image and EDS elemental distribution diagram of the cross-section of the superhydrophobic radiation cooling coating; Figure 9(a) Static droplets on the coating surface, (b) Water droplets bouncing, (c) Water splashing on the surface, (d) Underwater silver mirror, (e, f) Images of cleaning sand and dust from the coating; Figure 10 (a) Change in water contact angle after 120 wear cycles; (b) Change in reflectivity after 120 wear cycles. Figure 11 The superhydrophobic radiation cooling coating has a reflectivity of 0.3–2.0 μm and an infrared emissivity of 5.0–20 μm. Figure 12 (a) A physical image of the temperature measuring device, (b) the temperature of the bare glass and the superhydrophobic radiation cooling coating, and (c) the temperature difference between the glass and the superhydrophobic radiation cooling coating. Detailed Implementation

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Reagents and equipment Anhydrous ethanol, analytical grade: Shanghai Sinopharm Chemical Reagent Co., Ltd.; Epoxy resin E51, 3-aminopropyltriethoxysilane, 99%, triethoxy-1H,1H,2H,2H-tridecylfluoro-N-octylsilane (PFOTES), 97%, ammonia, ≥28% NH3 in H2O, electronic grade: Shanghai Maclean Biochemical Technology Co., Ltd.; Nano titanium dioxide, 99.8%, 100nm, golden red, lipophilic: Shanghai Aladdin Biotechnology Co., Ltd.; Hollow glass microspheres (GB): Minnesota Mining & Manufacturing Corporation, USA.

[0020] Thermostatic magnetic stirrer with heat collector, DF-101S: Zhengzhou Ketai Experimental Equipment Co., Ltd.; 4500°C forced-air drying oven: Shanghai Hengke Technology Co., Ltd.; Gravity-driven pneumatic spray gun, SUPRA TM Model 55: Bruker, Germany.

[0021] Example 1 Sample Preparation A hollow glass / TiO2 superhydrophobic radiation cooling coating, the coating comprising TiO2 and F-GB in a mass ratio of 2:3 and a molar ratio of E51:KH550 in a PFOTES-modified hollow glass microsphere GB, and E51:KH550 in a molar ratio of 1:2, wherein the total amount of particles to the amount of KH550-modified E51 is 5:2.

[0022] The superhydrophobic radiation cooling coating has a water contact angle of 154° and an adhesion strength of 1.417 MPa to the substrate. After 120 wear tests, it still maintains a hydrophobic effect with a contact angle of 140°. The superhydrophobic radiation cooling coating can achieve a water contact angle of 600 W / m. 2It achieves a cooling effect of 14°C under solar radiation intensity.

[0023] A method for preparing a hollow glass / TiO2 superhydrophobic radiation cooling coating includes the following steps: Step 1: Preparation of Fluorinated Hollow Glass Microspheres GB was dispersed in anhydrous ethanol, PFOTES was added, and the pH was adjusted to 7-8 with ammonia. The mixture was then heated in a water bath for 50-70 degrees Celsius. o C, after 2-3 hours, open the stopper and continue for 50-70 minutes. o Heating at C for 10-20 min removes ammonia, yielding a PFOTES-modified fluorinated hollow glass F-GB solution; wherein the amount of GB is 2.8-3.2 g, the amount of anhydrous ethanol is 12-20 ml, and the mass ratio of GB to PFOTES is (14-16):1.

[0024] Step 2: Preparation of superhydrophobic radiation cooling coating Add TiO2 to the F-GB solution prepared in step one, then add epoxy resin E51 and silane coupling agent KH550, totaling 1.8~2.2 g, and 50~70 g. o Heating in a water bath at C for 2 hours yields a precursor solution. Add 5-10 ml of this solution to the spraying apparatus, maintaining a distance of 15-20 cm between the spray gun and the substrate. Perform uniform spraying and place the mixture in a 50-70 mL container. o After baking in an oven at C for 3-5 minutes, repeat the above operation once to obtain the coating. The amount of TiO2 used is 1.8-2.2 g, and the molar ratio of epoxy resin E51 and silane coupling agent KH550 is 1:(1.8-2.2).

[0025] In this embodiment, the mass ratio of GB, TiO2 and epoxy resin E51 modified with silane coupling agent KH550 is (2.8~3.2): (1.8~2.2): (1.8~2.2).

[0026] Specifically: Preparation of Fluorinated Hollow Glass Microspheres Disperse 3g GB in 15ml anhydrous ethanol, add 0.2g PFOTES, adjust the pH to 7-8 with ammonia, and heat in a water bath for 60°C. o After 2 hours at C, the stopper was opened and the mixture was heated for another 10 minutes to remove the ammonia, resulting in a PFOTES-modified fluorinated hollow glass (F-GB) solution.

[0027] Preparation of superhydrophobic radiation cooling coating like Figure 1As shown, 2 g of TiO2 was added to the solution prepared above, along with 2 g of epoxy resin E51 and silane coupling agent KH550, in a molar ratio of 1:2. 60 o Heat in a C water bath for 2 hours, add 5 ml of precursor solution to the spraying device, and control the distance between the spray gun and the substrate to be 20 cm. Perform uniform spraying and place in a 60°C water bath. o After baking in an oven at C for 5 minutes, repeat the above steps once to obtain a coating with high reflectivity.

[0028] Example 2 Characterization and Testing (1) Structural characterization The surface morphology and thickness of the coating were observed using a scanning electron microscope (SEM, Hitachi Regulus 8220). The elemental composition was analyzed using energy-dispersive spectroscopy (EDS, EDAX Octane).

[0029] (2) Optical performance characterization The solar reflectance of the coating (0.3–2.5 μm) was measured using a UV-Vis-NIR spectrophotometer (TP-100) equipped with a BaSO4 integrating sphere. The mid-infrared emission spectrum (5–20 μm) was measured using a Fourier transform infrared spectrometer (Nicolet) equipped with a gold integrating sphere. TM The measurement was performed using the iS50.

[0030] (3) Characterization of wettability The contact angle of the coating was measured using a DSA25S (KRü SS, Germany). During the measurement, approximately 4 microliters of water were dropped onto the coating surface by squeezing the syringe. After the droplet stabilized, a side view was taken to measure the contact angle.

[0031] (4) Pull-out adhesion test To evaluate the adhesion of coatings on different substrates, a pull-out adhesion tester was used according to GB / T5210-2006 standard. The tester's adhesive was applied to the coating surface and the test head was attached, then cured at room temperature for 72 hours. The pressure relief valve of the tester was rotated completely counterclockwise to connect the sleeve to the test head. The test was conducted in "peak measurement" mode; the system was pressurized until the coating detached from the test head from the substrate, and the peak pressure at this point was recorded to quantify the adhesion between the coating and the substrate.

[0032] (5) Wear test The coating was placed on 100-mesh paper with a 50 g weight applied, and the coating was moved 10 cm. This cycle was repeated 120 times. The abrasion resistance was evaluated by comparing the solar reflectance and contact angle of the coating before and after wear.

[0033] Example 3 Results and Discussion Effect of PFOTES addition on GB modification of coating hydrophobic properties As a low surface energy modifier, the amount of PFOTES added significantly affects the hydrophobicity of the superhydrophobic radiation cooling coating. By changing the amount of PFOTES added to 0 g, 0.1 g, and 0.2 g, while keeping other conditions unchanged, coatings containing different amounts of F-GB were prepared, and their contact angles were measured.

[0034] In the solvent, the alkoxy groups of PFOTES hydrolyze to hydroxyl groups, which then combine with the silanol groups of GB, causing the long fluorinated links of PFOTES to branch onto the surface of GB, such as... Figure 2 As shown in Figure a, the surface morphology and elemental distribution of F-GB were observed using SEM and EDS. It can be seen that the surface morphology of unmodified GB and F-GB did not change. Figure 2 b,c). Elemental distribution of F-GB ( Figure 2 (d, e) indicates that F element is distributed on the surface of its SiO2 shell, indicating that the long fluorine chain of PFOTES was successfully grafted onto the surface of GB, proving that PFOTES successfully modified GB.

[0035] like Figure 3 As shown, the water contact angle of the prepared coating continuously increases with the gradual increase of PFOTES addition. Without PFOTES, the coating contact angle is only 130°. o This indicates that the micro-nano structure constructed solely by TiO2 and GB on the coating surface cannot achieve superhydrophobic properties. When the amount of PFOTES added reaches 0.2 g, the water contact angle of the coating is 151°. o To achieve a superhydrophobic effect, the recommended addition amount of PFOTES was determined to be 0.2 g, taking into account environmental protection considerations.

[0036] The Influence of Total Particle Quantity and Proportion on Coating Hydrophobicity and Reflectivity According to Snell's law, the greater the difference in refractive index (n) between two media, the greater the refractive index of light. This invention selects GB as the main component, with SiO2 (n=1.5), whose Si-O bonds exhibit mid-infrared radiation characteristics, giving the coating a high infrared emissivity. Simultaneously, TiO2 (n=2.7), which has a significantly different refractive index from air (n=1) and SiO2 (n=1.5), is chosen to enhance the coating's light scattering.

[0037] First, this invention prepared three coatings according to the mass ratio of TiO2:F-GB=3:2, and the total particle volume to polymer matrix mass ratios of 3:1, 5:2, and 3:2, respectively.

[0038] The effect of particle concentration on the reflectivity and hydrophobicity of the coating was studied by adjusting the total amount of filler, as shown in Figure (4a). As the ratio of total particle amount to polymer matrix increased, the reflectivity of the coating also improved synchronously, reaching its highest point when the ratio reached 5:2. However, as the ratio continued to increase, the reflectivity did not change significantly. This may be because oversaturation of particles affected light transmission, obstructing the light transmission channel and thus inhibiting effective light scattering. As shown in Figure (4b), with the increase of total particle amount, the content of F-GB also increased synchronously, reducing the surface energy of the coating and improving its hydrophobicity. When the ratio of total particle amount to polymer matrix reached 5:2, the contact angle of the coating also reached its highest point of 150°. o ( Figure 4 b). Continuing to increase the total number of particles may lead to a decrease in hydrophobic properties because it may damage the micro- and nano-structures constructed by the particles.

[0039] Based on a determined particle-to-polymer matrix mass ratio of 5:2, this invention further investigates the effect of the TiO2 / F-GB ratio on the coating's reflectivity and hydrophobic properties. TiO2 / F-GB composite coatings with different mass ratios of 2:1, 3:2, 1:1, 2:3, and 1:2 were prepared. The reflectivity and contact angle of these coatings are shown below. Figure 5 As shown.

[0040] When TiO2 and F-GB are mixed in mass ratios of 3:2 and 2:3, the coating exhibits high reflectivity. This is likely because these two ratios create a complex, micro-nano-level disordered surface structure, enhancing the coating's light scattering. However, with a TiO2:F-GB ratio of 2:3, the coating has lower surface energy, and the water contact angle is 154°. o This achieves a superhydrophobic effect and exhibits excellent self-cleaning properties. In summary, a particle-to-polymer matrix mass ratio of 5:2 and a TiO2-to-F-GB mass ratio of 2:3 were selected to construct the superhydrophobic radiation cooling coating.

[0041] The effect of the ratio of epoxy resin E51 to KH550 on coating adhesion Based on a predetermined particle-to-polymer matrix mass ratio of 5:2, and keeping the total mass of E51 and KH550 constant, three E51-KH550 polymer adhesive layers were prepared by adjusting the mixing ratios according to different molar ratios (1:1, 1:2, and 1:3). These layers were sprayed onto clean glass substrates, and their adhesion to the glass substrates was tested using a pull-out method. Figure 6As shown in the figure, when the ratio of E51 to KH550 is 1:1, the epoxy groups of E51 cannot completely react with the -NH2 groups of KH550, affecting adhesion to the substrate. When the ratio is 1:2, E51 and KH550 react completely, and the peak adhesion strength can reach 1.417 MPa. When the ratio of E51 to KH550 is 1:3, the amount of epoxy resin decreases due to the fixed total mass, resulting in a decrease in the adhesion strength of the coating. Therefore, this invention selects E51:KH550 = 1:2, which has the highest adhesion strength, to prepare a superhydrophobic radiation cooling coating.

[0042] Coating characterization A superhydrophobic radiation cooling coating was prepared using F-GB particles modified with 0.2 g of PFOTES, with a particle-to-matrix mass ratio of 5:2, a TiO2-to-F-GB mass ratio of 2:3, and an E51:KH550 molar ratio of 1:2. The surface morphology of the coating was characterized using SEM, as shown below. Figure 7 As shown, a distinct micro-nano structure is formed on the coating surface. This micro-nano structure helps to trap air on the coating surface, forming an air layer. This, in conjunction with the low surface energy of the F-GB, gives the coating superhydrophobic properties.

[0043] The coating thickness was characterized using SEM, and the cross-sectional elemental distribution of the coating was characterized using EDS. Figure 8 As shown in Figure a, the prepared coating thickness is approximately 100 micrometers, and TiO2 is uniformly distributed in the coating. Figure 8 b), F-GB, due to its hollow structure, is relatively lightweight and its main components are distributed on the coating surface ( Figure 8 (c, d). This gradient distribution of F-GB modified with low surface energy modifiers helps to effectively reduce the energy of the coating surface and reduce the interaction force between water droplets and the coating surface, thereby helping to improve the superhydrophobicity of the coating.

[0044] Coating performance Superhydrophobicity and self-cleaning To investigate the superhydrophobic and self-cleaning properties of the coating, this invention employed surface static droplet experiments, water droplet bouncing experiments, surface water splashing experiments, underwater silver mirror experiments, and experiments on cleaning sand and dust from the coating. For example... Figure 9As shown in Figure a, acid (pH=1), alkali (pH=14), dyed water (blue), tea, coffee, potassium permanganate solution, and milk were dropped onto a horizontally placed coating and glass, respectively. It can be seen that the droplets on the coating surface remained spherical for a long time, while the droplets on the glass surface spread out quickly. This demonstrates that the coating has good hydrophobicity and excellent self-cleaning effect against common liquid contaminants. When the superhydrophobic coating was placed at a certain angle, dyed water was dropped onto the coating surface using a dropper. The state of the water droplets was recorded using a digital camera. It can be seen that the water droplets bounced on the coating surface and then fell due to gravity until they left the coating surface. Figure 9 b). Place the superhydrophobic coating at a certain angle, and use a syringe to spray the dyeing water onto the coating surface, such as... Figure 9 As shown in Figure c, water can bounce off the coating surface and leave at a certain angle. When the coating is placed in water, a clearly visible reflective surface can be observed. This is because the micro-nano rough structure of the coating surface causes air layers to be trapped, forming the reflective surface. Figure 9 d). For example Figure 9 As shown in e and f, sand and dust are placed on the coating surface at a certain angle. Water is then dripped onto the coating using a dropper. The water droplets roll off the coating, effectively removing particles and foreign matter adhering to the surface. These experiments demonstrate that the prepared coating exhibits excellent superhydrophobicity and superior cleaning ability against common liquid and solid contaminants, providing a solid technical guarantee for the practical application of radiation cooling coatings.

[0045] Mechanical wear resistance test Superhydrophobic radiation cooling coatings, used in construction and various substrates, rely heavily on their resistance to mechanical wear when exposed to long-term environmental conditions for industrial application. This invention employs a linear friction test to evaluate the wear resistance of the coating. A superhydrophobic radiation cooling coating is sprayed onto a glass surface, with the coating side down on 100-grit sandpaper. A 50 g weight is placed on the glass side, and the coating is pushed 10 cm across the sandpaper. One reciprocating motion is recorded as one wear cycle. After 120 wear cycles, the changes in the coating's water contact angle and reflectivity are measured. Figure 10 As shown in Figure a, after 120 wear cycles, the contact angle of the coating decreases slightly, but still maintains 140°. o The contact angle exhibits good self-cleaning ability, while the reflectivity only decreases slightly in the visible light band and shows no significant change in other bands. This indicates that the worn coating still has a high reflectivity to sunlight, thus maintaining its radiative cooling capacity.

[0046] Optical performance Radiation cooling technology achieves its cooling effect by reflecting sunlight within the 0.3-2.5 μm wavelength range and simultaneously radiating heat into the cold outer space through an atmospheric transparency window between 8-13 μm. This requires the coating to have high reflectivity in the 0.3-2.5 μm wavelength range and high emissivity in the 8-13 μm wavelength range. The coating's reflectivity and infrared emissivity are as follows... Figure 11 As shown, the reflectivity reaches a maximum of 92.5% in the 0.3-2.5 μm wavelength range, consistent with the trend of the AM1.5 solar spectrum, indicating that the coating possesses high solar reflectivity. Simultaneously, the coating exhibits high emissivity in the 8-13 μm wavelength range. This is because the coating contains a large amount of Si-O-Si and CF, and due to molecular and functional group vibrations, the coating possesses excellent emissivity within the wavelength range of the atmospheric transparency window. The high reflectivity and emissivity of the coating provide reliable data support for its energy-free passive cooling effect.

[0047] Radiative cooling test To test the cooling capacity of the superhydrophobic radiation cooling coating, this invention uses a solar simulator (power: 600 W / m²). 2 This device simulates real sunlight by using a polystyrene foam box that effectively isolates external heat sources and is covered with an aluminum film. This helps block the penetration effect of environmental heat radiation and weakens the interference of external irradiation, ensuring that temperature changes depend solely on the coating itself. A PE film is used to seal the top layer, blocking heat and mass transfer caused by air convection and creating a near-ideal temperature measurement environment. During temperature measurement, a K-type thermocouple is placed under the coating and a blank control glass slide to track temperature changes in real time. A diagram of the actual device is shown below. Figure 12 As shown in Figure a. Data shows that the coating temperature is significantly lower than the ambient temperature ( Figure 12 (b) The temperature difference between the two can reach up to 14 degrees Celsius. o Approximately C. In summary, the superhydrophobic radiation cooling coating possesses excellent radiation cooling capabilities, providing assurance for its practical applications in daily life and production.

[0048] (1) The present invention prepared a superhydrophobic radiation cooling coating by spraying process, and obtained a coating with superhydrophobic properties, high solar reflectivity and high infrared emissivity by changing the amount of PFOTES added to modify GB, the ratio of total particles to polymer matrix, the ratio of TiO2 and F-GB particles, and the ratio of epoxy resin E51 to KH550.

[0049] (2) The prepared superhydrophobic radiation cooling coating has a strength of 154. oWith an optimal water contact angle, it achieves a superhydrophobic effect, exhibiting excellent cleaning ability for various solid and liquid contaminants. Furthermore, the coating's adhesion to the substrate reaches 1.417 MPa, and it maintains a contact angle of 140° even after 120 abrasion tests. o The coating exhibits a hydrophobic effect and shows no significant change in reflectivity, indicating that it has good durability.

[0050] (3) The superhydrophobic radiation cooling coating has high solar reflectivity and high infrared emissivity, and can achieve a temperature of 600 W / m 2 The solar radiation intensity reached 14 o The cooling effect of C indicates that the coating has a good radiative cooling effect.

Claims

1. A hollow glass / TiO2 superhydrophobic radiation cooling coating, characterized in that, The coating comprises TiO2 and F-GB in a mass ratio of 2:3 and E51:KH550 in a molar ratio of 1:2, obtained by PFOTES-modified hollow glass microspheres GB, with the total amount of particles to the amount of KH550-modified E51 being 5:

2.

2. The hollow glass / TiO2 superhydrophobic radiation cooling coating according to claim 1, characterized in that, The superhydrophobic radiation cooling coating has a water contact angle of 154° and an adhesion strength of 1.417 MPa to the substrate. After 120 wear tests, it still maintains a hydrophobic effect with a contact angle of 140°. The superhydrophobic radiation cooling coating can achieve a water contact angle of 600 W / m. 2 It achieves a cooling effect of 14°C under solar radiation intensity.

3. The method for preparing the hollow glass / TiO2 superhydrophobic radiation cooling coating according to claim 1, characterized in that, Includes the following steps: Step 1: Preparation of Fluorinated Hollow Glass Microspheres GB was dispersed in anhydrous ethanol, PFOTES was added, and the pH was adjusted to 7-8 with ammonia. The mixture was then heated in a water bath for 50-70 degrees Celsius. o C, after 2-3 hours, open the bottle stopper and continue for 50-70 minutes. o Heat at C for 10-20 min to remove ammonia water, and obtain PFOTES modified fluorinated hollow glass F-GB solution; Step 2: Preparation of superhydrophobic radiation cooling coating Add TiO2 to the F-GB solution prepared in step one, then add 1.8~2.2g of epoxy resin E51 and silane coupling agent KH550, and 50~70g of [unclear text - possibly a typo]. o Heating in a water bath at C for 2 hours yields a precursor solution. Add 5-10 ml of this solution to the spraying apparatus, maintaining a distance of 15-20 cm between the spray gun and the substrate. Perform uniform spraying and place the mixture in a 50-70 mL container. o After baking in an oven at C for 3-5 minutes, repeat the above steps once to obtain the coating.

4. The method according to claim 3, characterized in that, In step one, the amount of GB used is 2.8~3.2 g, and the amount of anhydrous ethanol used is 12~20 ml.

5. The method according to claim 3, characterized in that, In step one, the mass ratio of GB to PFOTES is (14~16):

1.

6. The method according to claim 3, characterized in that, In step two, the amount of TiO2 used is 1.8~2.2 g.

7. The method according to claim 3, characterized in that, In step two, the molar ratio of epoxy resin E51 and silane coupling agent KH550 is 1:(1.8~2.2).

8. The method according to claim 3, characterized in that, The mass ratio of GB, TiO2 and silane coupling agent KH550 modified epoxy resin E51 is (2.8~3.2): (1.8~2.2): (1.8~2.2).

9. The application of the hollow glass / TiO2 superhydrophobic radiation cooling coating according to claim 1 in building materials or various substrates.

Images