Preparation method of hydrophobic radiation refrigeration building film
Hydrophobic radiation-cooling building films were prepared by mixing alumina and silica with PVDF-HFP solution, which solved the problems of pollutant accumulation and insufficient hydrophobicity, and achieved efficient cooling and self-cleaning effects, making them suitable for building exterior environments.
Patent Information
- Application Number
- CN202610118358.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-03-27
AI Technical Summary
In the building sector, radiative cooling films suffer from problems such as pollutant accumulation and insufficient hydrophobicity, resulting in low utilization, poor durability, and high costs.
A hydrophobic radiation-cooling building film was prepared by dispersing alumina and silica in tetrahydrofuran and mixing it with a PVDF-HFP solution, removing air bubbles, and then forming a film. The film utilizes the porous structure and the hydrophobicity of the fluoropolymer to achieve self-cleaning ability.
It achieves high cooling performance, excellent hydrophobic properties and self-cleaning ability, making it suitable for building exterior environments and improving the durability and cleanliness of radiative cooling films.
Smart Images
Figure CN121736338A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of radiation refrigeration film, in particular to a preparation method of a hydrophobic radiation refrigeration building film. BACKGROUND
[0002] In the face of global warming, radiation refrigeration technology with high energy efficiency and passive heat management characteristics has become a research hotspot. Radiation refrigeration technology does not require additional energy to work, and by designing film materials, it uses the material itself to have high reflectivity in the 0.3-2.5 μm solar spectrum band and the 8-13 μm atmospheric transparent window in the mid-infrared band. The excess heat is radiated to the low-temperature universe in the form of thermal radiation, achieving the effect of refrigeration.
[0003] Every year, a large amount of energy is consumed to adjust the temperature to a suitable temperature for the human body due to high indoor temperature. Radiation refrigeration technology has attracted more and more attention from researchers in recent years because it does not require external energy input. This passive refrigeration technology without additional energy driving has great potential for energy saving and temperature control in the building field.
[0004] One of the difficulties of applying radiation refrigeration technology in the building field is that the radiation refrigeration material is generally exposed to the environment, and the cleaning difficulty of the surface stains greatly affects the radiation refrigeration efficiency. At the same time, building materials have high requirements for hydrophobicity. Therefore, it is of great significance to study a kind of easy-to-clean hydrophobic radiation refrigeration film.
[0005] In summary, the building field consumes a lot of energy today, and the radiation refrigeration film used in outdoor areas has problems such as environmental particulate pollution accumulation and insufficient liquid immersion hydrophobicity, which leads to low usage rate, poor durability, and high cost of the radiation refrigeration film in the building field. Therefore, in order for the radiation refrigeration film technology to have a wide application in the building field, the hydrophobicity and the ease of cleaning cannot be ignored. SUMMARY
[0006] Based on the above, the present application provides a preparation method of a hydrophobic radiation refrigeration building film.
[0007] To achieve the above-mentioned purpose, the present application provides the following solutions: One of the technical solutions of the present application is a preparation method of a hydrophobic radiation refrigeration building film, comprising the following steps: Disperse aluminum oxide and silicon dioxide in tetrahydrofuran to obtain a composite dispersion liquid; Mix the composite dispersion liquid and the PVDF-HFP solution uniformly to remove the bubbles in the system to obtain a precursor solution, film-forming, and obtain the hydrophobic radiation refrigeration building film.
[0008] The second technical scheme of the present application is a hydrophobic radiation refrigeration building film prepared by the preparation method.
[0009] The third technical scheme of the present application is an application of the hydrophobic radiation refrigeration building film in a building.
[0010] Compared with the prior art, the present application has the following beneficial effects: The hydrophobic radiation refrigeration building film has high refrigeration performance, excellent hydrophobic performance and self-cleaning ability, high reflectivity and stable physical structure. BRIEF DESCRIPTION OF DRAWINGS
[0011] In order to more clearly illustrate the technical schemes in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0012] Figure 1 SEM images of the hydrophobic radiation refrigeration building films prepared in Example 1, Example 4, Example 7 and Example 8; wherein (I) is Example 7, (II) is Example 8, (III) is Example 1, and (IV) is Example 4.
[0013] Figure 2 Optical reflectivity of the hydrophobic radiation refrigeration building films prepared in Example 1 to Example 6 in the wavelength range of 300nm-2500nm of sunlight.
[0014] Figure 3 Emissivity of the hydrophobic radiation refrigeration building films prepared in Example 1 to Example 6 in the 8-13µm wave band.
[0015] Figure 4 Contact angle measurement results of the hydrophobic radiation refrigeration building films prepared in Example 1 to Example 6.
[0016] Figure 5 Self-cleaning property test results of the hydrophobic radiation refrigeration building film prepared in Example 5. DETAILED DESCRIPTION
[0017] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.
[0018] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, concentration, intensity, or other values, an intermediate value of the range can be specifically recited herein; it is contemplated that it is possible that any intermediate value of this or any other range can be specifically recited herein. Any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All publications mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference is not an admission that it is prior art with respect to the present application.
[0020] Many modifications and variations of this application of the application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is to be understood that the application is not limited in scope by the described embodiments.
[0021] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed materials and methods.
[0022] The first aspect of the present application provides a preparation method of a hydrophobic radiation refrigeration building film, comprising the following steps: The alumina and the silicon dioxide are dispersed in tetrahydrofuran to obtain a composite dispersion liquid; The composite dispersion liquid is mixed with a PVDF-HFP solution, bubbles in the system are removed, film formation is performed, and a hydrophobic radiation refrigeration building film is obtained.
[0023] In a preferred embodiment of the present application, the mass ratio of the alumina to the silicon dioxide is 1: (2-4); the particle size of the alumina is 50 nm or 0.2 μm; and the particle size of the silicon dioxide is 2 μm or 10 μm.
[0024] If the particle size of the silicon dioxide is too small, obvious agglomeration will occur during the experiment, and therefore, the present application limits the particle size of the silicon dioxide to 2 μm or 10 μm.
[0025] In a preferred embodiment of the present application, the mass ratio of the alumina to tetrahydrofuran is 1:10.
[0026] In a preferred embodiment of the present application, the PVDF-HFP solution is prepared by dissolving polyvinylidene fluoride-hexafluoropropylene copolymer in N-methyl pyrrolidone.
[0027] In a preferred embodiment of the present application, the PVDF-HFP solution comprises 10%-20% polyvinylidene fluoride-hexafluoropropylene copolymer and the balance of N-methyl pyrrolidone by mass percentage.
[0028] In a preferred embodiment of the present application, the composite dispersion liquid is mixed with the PVDF-HFP solution by mechanical dispersion at a speed of 300 r / min for 10 minutes at room temperature with a magnetic stirrer to ensure sufficient wetting of the two-phase interface. Subsequently, it is treated in an ultrasonic disperser at room temperature for 45 minutes to collapse residual aggregates and optimize the spatial distribution uniformity of the particles. The present application does not make special limitations on the condition settings (such as power, frequency, etc.) of the ultrasonic disperser, and the condition settings commonly used by those skilled in the art are adopted.
[0029] In a preferred embodiment of the present application, the volume ratio of the composite dispersion liquid to the PVDF-HFP solution is 1:1.
[0030] The system is treated by vacuum extraction under negative pressure conditions (-0.1 MPa) to remove the air bubbles remaining in the system.
[0031] In a preferred embodiment of the present application, the film formation is performed by pouring the precursor solution into a culture dish and naturally air-drying at room temperature in a fume hood to form a film.
[0032] The second aspect of the present application provides a hydrophobic radiation refrigeration building film prepared according to the preparation method described above.
[0033] The third aspect of the present application provides the use of the hydrophobic radiation refrigeration building film described above in buildings.
[0034] In a preferred embodiment of the present application, the hydrophobic radiation refrigeration building film is adhered to the surface of a building substrate using a film coating method. The substrate includes a wood board, a polyethylene plastic board, or an aluminum plate.
[0035] The application also carries out comparative experiments of multiple groups of different particle sizes and different mass fractions of composite dispersants, and the experimental results show that the composite dispersion system prepared by mixing Al2O3 and SiO2 particles in a mass ratio of 1:4 shows significant instability, and a clear phase separation interface is observed after standing for 3 hours. The dispersion system with a mass ratio of Al2O3 to SiO2 of 1:2 has better stability. Then, the prepared radiation cooling film surface is characterized by SEM, and the characterization results show that the surfaces of the two formulations containing 10 μm SiO2 particles (10 μm SiO2+50 nm Al2O3, 10 μm SiO2+0.2 μm Al2O3) are flat, and a large number of Al2O3 particles and agglomerates are attached to the surface of 10 μm SiO2 particles. In comparison, the two formulations containing 2 μm SiO2 (2 μm SiO2+50 nm Al2O3, 2 μm SiO2+0.2 μm Al2O3) exhibit completely different structural characteristics. The radiation cooling film surface forms a uniform three-dimensional porous network structure without particle agglomeration. This porous structure can improve the mechanical properties of the radiation cooling film, and also release the thermal stress generated by the film in a high temperature environment through the porous structure.
[0036] The substantial features of the application are: The application solves two major problems of radiation cooling technology in the actual building field: first, pollen particles, dust and other particles are easy to accumulate to form a light-shielding layer, affecting the performance of the radiation cooling film; second, most of the current radiation cooling films lack research on hydrophobic properties, resulting in liquid droplet infiltration, which destroys the internal structure of the radiation cooling film and the durability of the building wall.
[0037] In the experiment of verifying the cleaning ability of the prepared radiation cooling film, loess is covered on the surface of the film as a pollutant, and then tap water is used to simulate the rainwater in the natural environment to wash the loess pollutant on the surface of the film. It is observed that the loess is easily separated from the surface of the film under the washing of a small amount of water flow, and the washing water does not stay on the surface of the film for too long. Then, the pollutant is replaced with sand, and the result is similar to that of the loess pollutant. Through this simulation experiment, it can be found that the radiation cooling film has good self-cleaning effect in the field environment, effectively reducing the adhesion of pollutants.
[0038] PVDF itself as a kind of fluorine-containing waterproof polymer, when its proportion increases from 10% to 20%, the fluorine-containing structure on the surface of the film is more, so the waterproof effect is better, the hydrophobicity of the radiation cooling film is improved, and the performance is prevented from being affected by liquid drop infiltration. The reason why the waterproof performance of the formula containing 50nm Al2O3 particles is better is that the small particle Al2O3 can be more uniformly dispersed in the dispersion treatment, avoid the self particles from holding together, and form a concave-convex structure similar to the surface of a lotus leaf on the surface of the film. The structure reduces the contact area between the liquid drop and the film, so that the liquid drop can roll off more easily.
[0039] Meanwhile, in the cooling performance test of the radiation cooling film, 50nm Al2O3-2μm SiO2 (1:2)-20% PVDF shows excellent refrigeration effect on the three substrates, and the maximum temperature drop can reach 15.68℃ in the application of the wood board substrate, which has very considerable refrigeration performance.
[0040] The technical solutions described in the application are conventional solutions in the art if not specifically stated, and the reagents or raw materials used are purchased from commercial channels or disclosed if not specifically stated.
[0041] The technical solutions provided by the application will be described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the application.
[0042] Example 1 (1) Cleaning of the substrate: the culture dishes used in the experiment were cleaned with deionized water to remove surface adhesions and other surface impurities, and then the culture dishes were ultrasonically treated with anhydrous ethanol and deionized water for 30 minutes, respectively, to remove organic matter and other particles adsorbed on the culture dishes, and finally dried in a 60℃ drying oven for 1 hour. The obtained dry and clean culture dishes are conducive to the preparation and demolding of the subsequent radiation cooling film.
[0043] (2) Preparation of PVDF-HFP solution: 1g of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) particles were accurately weighed and placed in a beaker, then 9g of N-methyl pyrrolidone (NMP) was also added to the beaker, and the solution was placed in a magnetic stirrer under room temperature conditions. A magnetic stirrer was added to the solution, and the stirring speed was set to 300r / min. The solution was continuously stirred for 7 hours to make the solution uniformly mixed and fully dissolved. After the PVDF-HFP particles were completely dissolved in the NMP, the PVDF-HFP solution was prepared.
[0044] (3) Functional particle dispersion treatment: Two kinds of particles, alumina and silica, were used as functional particles and dispersed in different mass ratios. The preparation process was as follows: 1 g of Al2O3 powder with a particle size of 50 nm and 2 g of SiO2 powder with a particle size of 2 μm were weighed and dispersed in 10 g of tetrahydrofuran (THF) solvent. To prevent impurities such as dust in the air from contaminating the sample, a thin film was covered on the mouth of the beaker to seal it during the experiment. Then the solution was placed in a magnetic stirrer and stirred at a speed of 300 r / min for 30 minutes at room temperature to disperse the functional particles uniformly in the organic solvent, and a composite dispersion liquid with a certain mass fraction ratio of functional particles was prepared.
[0045] (4) Preparation of PVDF-functional particle composite radiation cooling film: The above composite dispersion liquid and the PVDF-HFP solution prepared in step (2) were mixed in a volume ratio of 1:1, and mechanically dispersed at a speed of 300 r / min for 10 minutes in a room temperature environment by a magnetic stirrer to ensure that the two-phase interface was fully infiltrated. Then it was placed in an ultrasonic disperser and treated at room temperature for 45 minutes to collapse the residual aggregates by cavitation effect and optimize the spatial distribution uniformity of the particles. Finally, the dispersion system was transferred to a vacuum box to remove the air bubbles remaining in the system under negative pressure conditions to eliminate the structural defects caused by micro-bubbles during film formation, and a PVDF-functional particle composite dispersion system (i.e. precursor solution) was obtained.
[0046] (5) Preparation of hydrophobic radiation cooling building film: The above precursor solution was introduced into a culture dish and naturally air-dried into a film (film thickness 303.78 μm) at room temperature in a fume hood, and the film was placed on the surface of different building substrates.
[0047] Example 2 The difference between Example 1 and Example 2 is only that the amount of polyvinylidene fluoride-hexafluoropropylene copolymer used in step (2) is 1.5 g and the amount of N-methyl pyrrolidone used is 8.5 g; the rest of the steps and parameters are the same as those of Example 1.
[0048] Example 3 The difference between Example 1 and Example 3 is only that the amount of polyvinylidene fluoride-hexafluoropropylene copolymer used in step (2) is 2 g and the amount of N-methyl pyrrolidone used is 8 g; the rest of the steps and parameters are the same as those of Example 1.
[0049] Example 4 The difference between Example 1 and Example 4 is only that the particle size of the Al2O3 powder in step (3) is 0.2 μm; the rest of the steps and parameters are the same as those of Example 1.
[0050] Example 5 The only difference from Example 2 is that the particle size of Al2O3 powder in step (3) is 0.2 μm; the other steps and parameters are the same as in Example 2.
[0051] Example 6 The only difference from Example 3 is that the particle size of Al2O3 powder in step (3) is 0.2 μm; the other steps and parameters are the same as in Example 3.
[0052] Example 7 The only difference from Example 1 is that the mass of SiO2 powder in step (3) is 4g; the other steps and parameters are the same as in Example 1.
[0053] Example 8 The only difference from Example 7 is that the particle size of the SiO2 powder in step (3) is 10 μm; all other steps and parameters are the same as in Example 7. Performance tests were conducted on the hydrophobic radiation-cooling building films prepared in Examples 1-8: 1. SEM characterization of the microstructure of the thin film surface SEM images of the hydrophobic radiation-cooling building films prepared in Examples 1, 4, 7, and 8 are shown below. Figure 1 As shown, by Figure 1 It can be observed that significant particle agglomeration occurred on the surface of the 10 µm SiO2 PSA film, while in the 2 µm SiO2 PSA film, SiO2 and Al2O3 particles were dispersed in the matrix, forming a relatively obvious particle-embedded structure. The main reason is that during the "stirring and dispersing" stage of material preparation, the larger SiO2 particles in the PSA matrix settle rapidly and are prone to agglomeration. Figure 1 In the (II) localized agglomeration phenomenon, SiO2 particles of the same large diameter carry greater kinetic energy during stirring, and are difficult to break apart after colliding and agglomerating with other particles. Agglomerated particles will block the porous channels of PVDF-HFP, reduce the thermal insulation performance, and make the mechanical properties of the material uneven. Film cracking will occur at the agglomeration points. Figure 1 In (III) and (IV), the surface morphology of films with different Al2O3 particle sizes and 2µm SiO2 at a mass ratio of 1:2 under a 10% PVDF-HFP matrix concentration is shown. The results also show that the larger 0.2µm Al2O3 particles are more likely to cause pore blockage in the film than the smaller 50nm Al2O3 particles. However, since the mass ratio of Al2O3 to SiO2 is 1:2, the particles do not show excessive agglomeration.
[0054] 2. Measurement of solar reflectivity and emissivity of hydrophobic radiative cooling building films The optical reflectivity of the hydrophobic radiation cooling building films prepared in Examples 1 to 6 was measured in the wavelength range of 300 nm-2500 nm of sunlight by using a UV-Vis-NIR spectrophotometer of model UV-3600Plus produced by SHIMADZU. After the reflectivity of the above six radiation cooling films was tested in the wavelength range of 300 nm-2500 nm of sunlight by the UV-Vis-NIR spectrophotometer, it was found that the influence mechanism of the PVDF-HFP solution with different mass fractions on the combination of 50 nm Al2O3-2 μm SiO2 (mass ratio 1:2) and 0.2 μm Al2O3-2 μm SiO2 (mass ratio 1:2) was that the reflectivity in the visible light band increased with the increase of the mass fraction of PVDF under the same functional particle formula. Among them, the film of PSA50-20 (Example 3) had the best reflectivity, and the highest reflectivity reached 90.25% (as shown in Figure 2 ; Figure 2 In the above, PSA50-10 represents Example 1, PSA50-15 represents Example 2, PSA50-20 represents Example 3, PSA0.2-10 represents Example 4, PSA0.2-15 represents Example 5, and PSA0.2-20 represents Example 6. The emissivity of the film in the wavelength range of 8-13 μm was tested by using a Fourier infrared microscopic imaging spectrometer Nicolet6700 with a diffuse reflection integrating sphere, and the highest emissivity reached 97.33% (as shown in Figure 3 ; Figure 3 In the above, PSA50 10 represents Example 1, PSA50 15 represents Example 2, PSA50 20 represents Example 3, PSA0.2 10 represents Example 4, PSA0.2 15 represents Example 5, and PSA0.2 20 represents Example 6.
[0055] 3. Test of hydrophobic performance and self-cleaning performance of the hydrophobic radiation cooling building film In order to characterize the hydrophobic performance of the hydrophobic radiation cooling building films prepared in Examples 1 to 6, a high-speed camera of model PCO.DIMAX.HS was used to analyze the wetting behavior of liquid droplets on the film. The experiment was carried out in an environment with a constant temperature of 26℃, and a liquid gun was used to drop water vertically on the film surface in sequence, and then a high-speed camera was used to record the static images of the liquid droplets on the film surface. The results are shown in Figure 4 ; Figure 4In the figure, 10% PVDF-HFP, 0.2 μm Al2O3 represents Example 4; 15% PVDF-HFP, 0.2 μm Al2O3 represents Example 5; 20% PVDF-HFP, 0.2 μm Al2O3 represents Example 6; 10% PVDF-HFP, 50 nm Al2O3 represents Example 1; 15% PVDF-HFP, 50 nm Al2O3 represents Example 2; 20% PVDF-HFP, 50 nm Al2O3 represents Example 3).
[0056] The contact angle measurement results show that the contact angles of the hydrophobic radiation refrigeration building films prepared by Examples 1-6 using different formulations are significantly different. In terms of the mass fraction of PVDF, the two formulations containing 20% PVDF have larger contact angles and better hydrophobic performance than the formulations with a mass fraction of 10% and 15% PVDF. In terms of the formulation of functional particles, under the same mass fraction of PVDF, the formulation containing 50 nm Al2O3 has better hydrophobic performance than the formulation containing 0.2 μm Al2O3, and the contact angle of the formulation of Example 3 (corresponding to 20% PVDF-HFP in the figure) is about 120.5°.
[0057] The hydrophobic radiation refrigeration building film of Example 3 is selected as the experimental object. The deposition and scouring process of pollutants and rainwater in a natural environment are simulated, as shown in FIG. 6. Figure 5 As can be seen, the film surface is first covered with loess as a pollutant, and then tap water is sucked by a rubber bulb dropper to simulate the scouring of rainwater on the loess pollutant on the film surface in a natural environment. It can be found that the loess easily separates from the surface of the film under the scouring of a small amount of water flow, and the water flow does not stay on the surface of the film too much. Then the pollutant is replaced with sand, and the result is similar to that of the loess pollutant. Through this simulation experiment, it can be found that the hydrophobic radiation refrigeration building film has good self-cleaning effect in the field environment, effectively reducing the adhesion of pollutants.
[0058] 4. Cooling performance test of the hydrophobic radiation refrigeration building film In summary, the above measurement of the reflectivity of the hydrophobic radiation refrigeration building film in the solar wave band and the measurement of the contact angle, the system containing 10 μm SiO2 has insufficient optical performance and mechanical strength due to sedimentation and particle agglomeration, and the 10% and 15% PVDF systems have insufficient self-cleaning ability due to small droplet contact angles, so it is difficult to meet the demand for outdoor durability, so the present application finally selects two formulations of Examples 3 and 6 for cooling performance test of the hydrophobic radiation refrigeration building film.
[0059] The hydrophobic radiant cooling building film with the formula of Example 3 is superior to the hydrophobic radiant cooling building film with the formula of Example 6 in maximum temperature drop and temperature curve on the surface of three substrates (wood board, polyethylene plastic board and aluminum plate). In the test with wood board as the substrate, the hydrophobic radiant cooling building film of 50 nm Al2O3-2 μm SiO2 (1:2)-20% PVDF (Example 3) can bring a stable temperature drop of more than 10℃ during the day, and the maximum temperature drop is 15.68℃, which has very considerable refrigeration performance. The maximum temperature drops of the hydrophobic radiant cooling building film prepared in Example 3 on polyethylene plastic board and aluminum plate can reach 8.27℃ and 2.50℃, respectively.
[0060] It can be seen from the above examples and performance tests that the two functional particles, aluminum oxide and silicon dioxide, are dispersed and treated to form a composite dispersion liquid, and the composite dispersion liquid is mixed with a PVDF-HFP solution with a certain mass fraction by a magnetic stirrer, which effectively improves the hydrophobicity, self-cleaning property and refrigeration performance of the radiant cooling film, is suitable for large-scale application in outdoor scenes such as buildings, and promotes the better landing of the radiant cooling technology.
[0061] The above-described examples only describe the preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.
Claims
1. A method for preparing a hydrophobic radiation-cooled building thin film, characterized in that, Includes the following steps: Alumina and silica were dispersed in tetrahydrofuran to obtain a composite dispersion; The composite dispersion was mixed with the PVDF-HFP solution, and the air bubbles in the system were removed to obtain the precursor solution. The solution was then formed into a film to obtain a hydrophobic radiation-cooled building film.
2. The preparation method according to claim 1, characterized in that, The mass ratio of alumina to silicon dioxide is 1:(2-4); the particle size of the alumina is 50 nm or 0.2 μm; the particle size of the silicon dioxide is 2 μm or 10 μm.
3. The preparation method according to claim 1, characterized in that, The mass ratio of alumina to tetrahydrofuran is 1:
10.
4. The preparation method according to claim 1, characterized in that, The PVDF-HFP solution is prepared by dissolving polyvinylidene fluoride-hexafluoropropylene copolymer in N-methylpyrrolidone.
5. The preparation method according to claim 4, characterized in that, The PVDF-HFP solution comprises 10%-20% polyvinylidene fluoride-hexafluoropropylene copolymer and the balance N-methylpyrrolidone by mass percentage.
6. The preparation method according to claim 1, characterized in that, The volume ratio of the composite dispersion to the PVDF-HFP solution is 1:
1.
7. The preparation method according to claim 1, characterized in that, The film formation process specifically involves introducing the precursor solution into a culture dish and air-drying it at room temperature to form a film.
8. A hydrophobic radiation-cooling building film prepared by the preparation method according to any one of claims 1-7.
9. The application of the hydrophobic radiation-cooling building film as described in claim 8 in buildings.
10. The application according to claim 9, characterized in that, A hydrophobic radiation-cooling building film is adhered to the surface of a building substrate using a film coating method.