Coating with passive radiation cooling function as well as preparation method and application thereof

Abstract

The invention provides a coating with a passive radiation cooling function and a preparation method and application thereof, the coating is prepared by fully mixing a radiation refrigeration layer material, an organic solvent and rod-like titanium dioxide, the components are simple, the raw material price is low, the preparation process is simple, and the cost is low. The coating formed by the rod-like titanium dioxide has a porous structure, not only has an excellent radiation refrigeration effect, but also has photocatalytic self-cleaning performance, and can further perform hydrophobic treatment on the rod-like titanium dioxide to enable the coating to have dual self-cleaning functions of photocatalysis and physical self-cleaning, so that the efficiency of the radiation refrigeration coating is greatly improved, and the service life is prolonged. After the coating with the passive radiation cooling function is sprayed to the surface of a textile substrate and dried, the surface of an obtained coating textile has a rough micro-nano structure, the scattering effect of inorganic particles and pores can be fully utilized, the reflectivity to sunlight is effectively increased, and then the radiation cooling effect is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of daytime radiative cooling materials, and particularly relates to a coating with passive radiative cooling function and a preparation method and application thereof. BACKGROUND

[0002] With the rapid growth of population and cities, the consumption of fossil fuels is increasing, and the resulting greenhouse gases will cause problems such as rising temperatures and frequent extreme weather. Existing research shows that global building energy consumption accounts for about 40% of total global energy consumption, and air conditioning refrigeration systems based on compressors account for one-fifth of building electricity consumption. The power required for refrigeration has exceeded the acceptable capacity of the urban power supply system, and building cooling has become an urgent energy problem. As a new type of passive cooling technology without energy consumption, radiative cooling is attracting more and more attention from researchers.

[0003] In a clear daytime, solar radiation is mainly composed of 6% ultraviolet radiation, 52% visible light radiation with a wavelength of 400-780 nm, and 42% near-infrared light radiation with a wavelength of 780-2500 nm. Among them, visible light and near-infrared light in the solar spectrum are the main causes of environmental heat production, especially in areas with relatively hot climates, the visible and near-infrared radiation heat production effect is also more significant. Passive radiative cooling materials can emit heat energy through the atmospheric window while reflecting solar energy, which has a significant cooling effect on objects.

[0004] Due to the dense urban buildings, asphalt and cement pavements have a larger heat absorption rate and smaller specific heat capacity than the soil and vegetation in the suburbs. Under the same solar irradiation, the urban ground temperature is higher than that in the suburbs, forming a heat island effect (UHI). The UHI effect will have a counteractive effect on the urban environment, forcing the urban temperature to rise, affecting the thermal comfort of urban residents, and in severe cases, even threatening the safety of residents' lives. In order to cope with the hot summer, it has become an urgent need to develop a building radiative cooling textile with high infrared emissivity to suppress the temperature rise of buildings.

[0005] The patent document with the publication number CN113861771A discloses a radiation refrigeration coating with a self-cleaning function and a preparation method and application thereof. The radiation refrigeration coating with the self-cleaning function comprises a refrigeration material layer and a self-cleaning finishing layer; the self-cleaning finishing layer is coated on the refrigeration material layer; the self-cleaning finishing layer contains styrene and acrylate monomer polymers, a hydrophobic agent and a thickening agent. By coating the self-cleaning finishing layer containing specific components on the surface of the refrigeration material layer, the coating can have good radiation refrigeration performance, a solar reflectivity of 97%, a thermal infrared band atmospheric window (8-13.5 μm) emissivity of 97%, and a full-band emissivity of 95%, and also has good self-cleaning function. Although the self-cleaning radiation refrigeration composite material layer prepared by the method has remarkable radiation cooling and hydrophobic effect, the material cost is high and the preparation process is complex.

[0006] The patent document with the publication number CN116102928A discloses a preparation method of a radiation refrigeration coating with super-hydrophobic performance. N,N-dimethylformamide and tetrahydrofuran are mixed and stirred to form a DMF and tetrahydrofuran mixed solution; polyvinylidene fluoride is dissolved in the mixed solution; polydimethylsiloxane and its curing agent SYLGARD 184 CURING AGENT are added to the mixed solution to obtain a colloidal mixed solution; small-particle-size polytetrafluoroethylene particles, large-particle-size polytetrafluoroethylene and fumed silica particles are added to the prepared mixed solution, heated in a water bath to obtain a mixed slurry; the surface of a substrate is fully coated with the prepared mixed slurry by using a doctor blade coating method; the substrate after coating is shaped at a relatively low temperature, and then dried by using a gradient method. A radiation refrigeration coating with super-hydrophobic performance can be obtained after the drying is completed. The film forming method is harsh and relatively difficult to produce in large area.

[0007] It can be seen that the production of the radiation refrigeration layer and related products in the prior art generally has problems such as complex preparation process, high raw material cost and difficulty in industrial production. SUMMARY

[0008] To solve the problems in the prior art, the present application provides a coating with passive radiation cooling function and a preparation method and application thereof. The coating is simple to prepare and has low raw material cost. When sprayed onto the surface of a textile, a flexible radiation refrigeration functional coating textile with self-cleaning performance can be obtained. The coating textile has excellent radiation refrigeration function and also has physical and chemical double self-cleaning performance, effectively resists bacteria and prevents external pollutants from polluting the coating, and overcomes the problems of poor cooling performance, complex preparation method and high cost of the radiation refrigeration layer in the prior art.

[0009] A coating with passive radiation cooling function is prepared from a radiation refrigeration layer material, an organic solvent and rod-shaped titanium dioxide.

[0010] The radiation cooling layer material is polyvinylidene fluoride-hexafluoropropylene copolymer (P(VDF-HFP)), polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS) or polymethyl methacrylate (PMMA).

[0011] The organic solvent is a mixture of acetone and ethyl acetate.

[0012] As a preferred, the radiation cooling layer material is polyvinylidene fluoride (PVDF).

[0013] As a preferred, the mass ratio of the radiation cooling layer material to acetone is 1: (7-10). Further preferably, it is 1:10.

[0014] As a preferred, in the organic solvent, the mass ratio of acetone to ethyl acetate is (5-15):1. Further preferably, it is 9:1.

[0015] As a preferred, the mass ratio of the radiation cooling layer material to the rod-shaped titanium dioxide is 10: (0.5-3). Further preferably, it is 10:1.

[0016] As a preferred, the rod-shaped titanium dioxide is prepared by the following method:

[0017] The photocatalytic titanium dioxide and the infrared reflective titanium dioxide are stirred and mixed with a sodium hydroxide solution, then transferred to a high-pressure reactor for reaction. After the reaction, the pH is adjusted to 1.5, and then washed, dried and calcined to obtain the rod-shaped titanium dioxide (TNr).

[0018] In the preparation process, the NaOH solution destroys some Ti-O bonds in the precursor (photocatalytic titanium dioxide and infrared reflective titanium dioxide), so that the Na2Ti2O5 nanosheet is formed in the subsequent hydrothermal process. The Na2Ti2O5 nanosheet grows continuously due to its high surface energy until it curls, and finally forms the rod-shaped titanium dioxide. The rod-shaped titanium dioxide not only has excellent reflective performance of the infrared reflective titanium dioxide, but also has photocatalytic performance of the photocatalytic titanium dioxide.

[0019] The photocatalytic titanium dioxide used is a commercial photocatalyst P25 with a particle size of 20-50 nm and excellent photocatalytic performance. The infrared reflective titanium dioxide is a micron-sized square titanium dioxide 550 with a particle size of 1-5 μm.

[0020] The rod-shaped titanium dioxide prepared by the above method has a width of 100-500 nm and a length of 0.5-6 μm. The aspect ratio is 5-40.

[0021] As a preference, the mass ratio of the photocatalytic titanium dioxide and the infrared reflective titanium dioxide is 1:(1-5). Further preferably, it is 1:(1-3). More preferably, it is 1:3.

[0022] As a preference, the mass-volume ratio of the total amount of titanium dioxide (including the photocatalytic titanium dioxide and the infrared reflective titanium dioxide) and the sodium hydroxide solution is 1:(50-80) g / mL. More preferably, it is 1:70 g / mL.

[0023] As a preference, the concentration of the sodium hydroxide solution is 5-15 mol / L. Further preferably, it is 10 mol / L.

[0024] As a preference, the reaction temperature in the high-pressure reactor is 150-200 ℃, and the reaction time is 15-30 h. As a further preference, the reaction temperature is 180 ℃, and the reaction time is 24 h.

[0025] As a preference, the pH is adjusted by using an HCl solution.

[0026] As a preference, the calcination temperature is 400-800 ℃, and the calcination time is 1-4 h. As a further preference, the calcination temperature is 600 ℃, and the calcination time is 2 h.

[0027] As a specific preference, the rod-shaped titanium dioxide is prepared by the following method:

[0028] The photocatalytic TiO2 (P25) and the infrared reflective TiO2 (550) nanoparticles are mixed with a 10 mol / L NaOH solution, and after stirring for 30 min, the mixture is transferred to a high-pressure reactor and reacted at 180 o C for 24 h. After adjusting the pH to 1.5 by using an HCl solution, the rod-shaped titanium dioxide (TNr) is obtained by washing, drying, and calcining at 600 o C.

[0029] As a preference, the obtained rod-shaped titanium dioxide is hydrophobically modified by using 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), and the modified rod-shaped titanium dioxide is used for the preparation of subsequent coatings.

[0030] Specifically, the TNr is dispersed in a mixed solution of deionized water / anhydrous ethanol, ultrasonically treated for 10 min, and the PFDTS is added to the mixed solution, and the reaction is carried out by magnetic stirring in a water bath at room temperature for 12 h. After the reaction is completed, the modified rod-shaped titanium dioxide (F-TNr) is obtained by washing and drying.

[0031] As preferred, the mass ratio of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane to rod-shaped titanium dioxide is 1: (1-3). Further preferred is 1:2.

[0032] As preferred, the volume ratio of deionized water to anhydrous ethanol in the mixed solution is 1:2.

[0033] As preferred, the mass-volume ratio of TNr to the mixed solution of deionized water / anhydrous ethanol is 1: (80-120) g / mL. Further preferred is 1:100 g / mL.

[0034] A preparation method of the coating with passive radiative cooling function as described above, dissolving the radiative refrigeration layer material in an organic solvent, then adding rod-shaped titanium dioxide, stirring uniformly to obtain the coating with passive radiative cooling function.

[0035] As preferred, after adding rod-shaped titanium dioxide, stirring at 500-600 rpm for 2-3 h to make the material mix uniformly.

[0036] A preparation method of the passive radiative cooling function coating textile with self-cleaning performance, spraying the coating with passive radiative cooling function as described in any one of the above to the surface of the textile substrate under a pressure of 0.3-0.6 MPa, drying at room temperature, and waiting for the solvent to completely evaporate to obtain the passive radiative cooling function coating textile with self-cleaning performance.

[0037] As preferred, the spraying pressure is 0.4 MPa.

[0038] The textile substrate can be cotton fabric, polyamide fabric, polyester fabric or glass fiber fabric.

[0039] During the drying of the coating, acetone and ethyl acetate gradually evaporate, forming a porous structure in the interior and surface of the coating; in addition, the scattering synergistic effect of rod-shaped titanium dioxide and pores effectively increases the reflectivity of the coating to sunlight, improving the radiative refrigeration effect of the coating textile. In addition, the addition of rod-shaped titanium dioxide in the coating makes the surface of the dried coating form a rough micro-nano structure; when rod-shaped titanium dioxide with further hydrophobic treatment is used, the low surface energy characteristics and the rough micro-nano structure of the coating surface are combined, making the coating textile have super-hydrophobic self-cleaning function. At the same time, the presence of rod-shaped titanium dioxide also endows the coating textile with photocatalytic self-cleaning performance, combined with super-hydrophobic self-cleaning, making the coating textile have both physical and chemical dual self-cleaning functions. The acquisition of dual self-cleaning function can keep the surface of the coating textile clean, effectively improve the radiative refrigeration efficiency of the coating textile, and prolong its service life.

[0040] A passive radiative cooling functional coating textile with self-cleaning performance is prepared by the preparation method of the passive radiative cooling functional coating textile with self-cleaning performance.

[0041] Preferably, the thickness of the radiative cooling layer is 100-300 microns.

[0042] The radiative cooling coating textile with self-cleaning performance provided by the application comprises a two-layer structure of a passive radiative cooling layer (dried after being sprayed with the coating material with passive radiative cooling function) and fabric fibers (substrate), and the passive radiative cooling layer has a high influence on the UV-Vis-NIR reflection and IR emission of the substrate, and can improve the reflectivity in the visible light range and the emissivity in the mid-infrared range. In addition, when the rod-shaped titanium dioxide after hydrophobic treatment is used, the passive radiative cooling layer has super-hydrophobic and photocatalytic properties, which can not only chemically degrade organic matter and bacteria, but also physically self-clean the dust and degradation products attached to the surface of the coating, so that the cooling effect of the coating is more durable. Therefore, this work successfully proves the application of radiative cooling in textiles, and provides more possibilities for the preparation of low-cost and multifunctional building textiles.

[0043] The radiative cooling layer (coating) formed by the coating material with passive radiative cooling function of the application is suitable for reflecting sunlight in the 0.3-2.5 micron band and has high emissivity in the 8-13 micron band, so that the radiative cooling layer is suitable for emitting heat in the form of infrared radiation through the "atmospheric window". The sunlight reflectivity of the coating textile of the application can be up to 94%, and the mid-infrared emissivity can be up to 0.92. The above-mentioned radiative cooling layer is a rough and porous structure added with inorganic fillers (rod-shaped titanium dioxide), which fully utilizes the scattering effect of inorganic particles and pores to increase the reflectivity of sunlight.

[0044] Compared with the prior art, the application has the following beneficial effects:

[0045] The coating material with passive radiative cooling function of the application is prepared by fully mixing radiative cooling layer materials, organic solvents and rod-shaped titanium dioxide, and has simple components, low raw material prices, simple preparation process and low cost. The coating formed thereby has a porous structure, not only has excellent radiative cooling effect, but also has photocatalytic self-cleaning performance, and the rod-shaped titanium dioxide can be further hydrophobic treated to make the coating have both photocatalytic and physical self-cleaning functions, greatly improving the efficiency of the radiative cooling coating and prolonging the service life.

[0046] The surface of the coated textile obtained after spraying the coating material with passive radiative cooling function of the application to the surface of the textile substrate and drying has a rough micro-nano structure, and can fully utilize the scattering effect of inorganic particles and pores to effectively increase the reflectivity to sunlight, thereby improving the radiative cooling effect. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 SEM image for characterization of the morphology of the prepared rod-shaped titanium dioxide;

[0048] Figure 2 SEM image for characterization of the surface morphology of the passive radiative cooling functional coated textile prepared in Example 1;

[0049] Figure 3 SEM image for characterization of the internal pore morphology of the passive radiative cooling functional coated textile prepared in Example 1;

[0050] Figure 4 Surface water contact angle characterization image of the passive radiative cooling functional coated textile prepared in Example 1;

[0051] Figure 5 Infiltration state of different liquid pollutants on the surface of the passive radiative cooling functional coated textile prepared in Example 1;

[0052] Figure 6 Comparison chart of the passive radiative cooling functional coated textile prepared in Example 1 before and after photocatalytic degradation of dyes; wherein (c1), (c2), (c3) are respectively comparison charts of coated fabrics before and after degradation of methylene blue, rhodamine B and oil red;

[0053] Figure 7 Bacteriostatic effect chart of the passive radiative cooling functional coated textile prepared in Example 1;

[0054] Figure 8 Reflectivity characterization chart of the passive radiative cooling functional coated textile prepared in Example 1;

[0055] Figure 9 Emissivity characterization chart of the passive radiative cooling functional coated textile prepared in Example 1;

[0056] Figure 10 Reflectivity characterization comparison chart of the passive radiative cooling functional coated textiles prepared in Example 1, Comparative Examples 1 and 2;

[0057] Figure 11 Temperature test characterization comparison chart of the passive radiative cooling functional coated textile prepared in Example 1 and the glass fiber fabric in Comparative Example 3. DETAILED DESCRIPTION

[0058] The present invention will be further described below with reference to specific embodiments.

[0059] In the following examples, rod-shaped titanium dioxide was prepared by the following method:

[0060] 0.25 g of photocatalytic TiO2 (P25) and 0.75 g of infrared reflective TiO2 nanoparticles (550) were mixed with 70 ml of 10 mol / L NaOH solution and stirred for 30 min. The mixture was then transferred to a high-pressure reactor and heated at 180 o After the reaction was completed, the pH was adjusted to 1.5 with HCl solution. The product was washed and dried, and then calcined at 600 °C for 2 h to obtain rod-shaped titanium dioxide (TNr). The SEM image of the obtained product is shown in FIG. Figure 1 .Depend on Figure 1 It can be seen that the obtained rod-shaped titanium dioxide has different lengths and a wide aspect ratio distribution; specifically, the width of the rod-shaped titanium dioxide is 100~500nm, the length is 0.5~6 μm, and the aspect ratio is 5~40.

[0061] Among them, photocatalytic TiO2 (P25) was purchased from Evonik Specialty Chemicals Co., Ltd.

[0062] Infrared reflective TiO2 nanoparticles (550) were purchased from Pannengtuo Company.

[0063] Optionally, the rod-shaped titanium dioxide is further subjected to a hydrophobic treatment:

[0064] 2 g of TNr was dispersed in a 200 ml mixed solution of deionized water / anhydrous ethanol (volume ratio of the two was 1:2) and ultrasonically treated for 10 min. 1 g of PFDTS (1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane) was added to the mixed solution and reacted with magnetic stirring in a water bath at room temperature for 12 h. After the reaction, the modified rod-shaped titanium dioxide was finally obtained after washing and drying, which was recorded as F-TNr.

[0065] Example 1

[0066] (1) dissolving and dispersing polymer PVDF in a mixed solution of acetone and ethyl acetate (wherein the mass ratio of acetone to ethyl acetate is 9:1), adding modified rod-shaped titanium dioxide (F-TNr) (wherein the mass ratio of PVDF, acetone, and rod-shaped titanium dioxide is 10:100:1), stirring at 550 rpm for 2.5 h until uniform, and obtaining a daytime passive radiation coating dispersion (a coating having a passive radiation cooling function);

[0067] (2) Pour the daytime passive radiation coating dispersion liquid into a spray gun, spray on the surface of the glass fabric at a pressure of 0.4 MPa using a nozzle with a diameter of 0.5 mm, dry at room temperature, and after the solvent is completely volatilized, the coating textile with passive radiation cooling function is obtained.

[0068] The coating textile with passive radiation cooling function prepared in this example has a coating thickness of 300 μm; the solar reflectivity of the coating textile is 0.94 (as shown in Figure 8 The atmospheric window emissivity is 0.92 (as shown in Figure 9 ).

[0069] Example 2

[0070] (1) Dissolve and disperse the polymer PVDF in a mixed solution of acetone and ethyl acetate (wherein the mass ratio of acetone to ethyl acetate is 9:1), add unmodified rod-shaped titanium dioxide (TNr) (wherein the mass ratio of PVDF, acetone, and rod-shaped titanium dioxide is 10:100:1), stir at 550 rpm for 2.5 h, and after uniform stirring, obtain a daytime passive radiation coating dispersion liquid (coating with passive radiation cooling function);

[0071] (2) Pour the daytime passive radiation coating dispersion liquid into a spray gun, spray on the surface of the glass fabric at a pressure of 0.4 MPa using a nozzle with a diameter of 0.5 mm, dry at room temperature, and after the solvent is completely volatilized, the coating textile with passive radiation cooling function is obtained;

[0072] The coating textile with passive radiation cooling function prepared in this example has a coating thickness of 300 μm; the solar reflectivity of the coating textile is 0.89, the atmospheric window emissivity is 0.90, and the water droplet contact angle on the surface is 92.4°.

[0073] Example 3

[0074] (1) Dissolve and disperse the polymer PVDF in a mixed solution of acetone and ethyl acetate (wherein the mass ratio of acetone to ethyl acetate is 9:1), add modified rod-shaped titanium dioxide (F-TNr) (wherein the mass ratio of PVDF, acetone, and rod-shaped titanium dioxide is 10:100:2), stir at 550 rpm for 2.5 h, and after uniform stirring, obtain a daytime passive radiation coating dispersion liquid (coating with passive radiation cooling function);

[0075] (2) Pour the daytime passive radiation coating dispersion liquid into a spray gun, spray on the surface of the glass fabric at a pressure of 0.4 MPa using a nozzle with a diameter of 0.5 mm, dry at room temperature, and after the solvent is completely volatilized, the coating textile with passive radiation cooling function is obtained;

[0076] The coating thickness of the coating textile with passive radiative cooling function prepared in the embodiment is 250 μm; the solar reflectance of the coating textile is 0.90, and the atmospheric window emissivity is 0.91.

[0077] Example 4

[0078] (1) Dissolve and disperse the polymer PVDF into a mixed solution of acetone and ethyl acetate (wherein the mass ratio of acetone to ethyl acetate is 9:1), add modified rod-shaped titanium dioxide (F-TNr) (wherein the mass ratio of PVDF, acetone, and rod-shaped titanium dioxide is 10:100:3), stir at 550 rpm for 2.5 h, and uniformly stir to obtain a daytime passive radiation coating dispersion (coating with passive radiative cooling function);

[0079] (2) Pour the daytime passive radiation coating dispersion into a spray gun, spray on the surface of the glass fabric using a 0.5 mm caliber nozzle at a pressure of 0.4 MPa, dry at room temperature, and after the solvent is completely volatilized, the coating textile with passive radiative cooling function is obtained;

[0080] The coating thickness of the coating textile with passive radiative cooling function prepared in the embodiment is 250 μm; the solar reflectance of the coating textile is 0.91, and the atmospheric window emissivity is 0.90.

[0081] Comparative Example 1

[0082] (1) Dissolve and disperse the polymer PVDF into a mixed solution of acetone and ethyl acetate (wherein the mass ratio of acetone to ethyl acetate is 9:1), add nano titanium dioxide P25 with a particle size of 20-50 nm (wherein the mass ratio of PVDF, acetone, and titanium dioxide is 10:100:1), stir at 550 rpm for 2.5 h, and uniformly stir to obtain a daytime passive radiation coating dispersion (coating with passive radiative cooling function);

[0083] (2) Pour the daytime passive radiation coating dispersion into a spray gun, spray on the surface of the glass fabric using a 0.5 mm caliber nozzle at a pressure of 0.4 MPa, dry at room temperature, and after the solvent is completely volatilized, the coating textile with passive radiative cooling function is obtained;

[0084] The coating thickness of the coating textile with passive radiative cooling function prepared in the embodiment is 250 μm; the solar reflectance of the coating textile is 0.91, and the atmospheric window emissivity is 0.90.

[0085] Comparative Example 2

[0086] (1) Dissolve and disperse the polymer PVDF into a mixed solution of acetone and ethyl acetate (the mass ratio of acetone to ethyl acetate is 9:1), add the infrared reflective titanium dioxide 550 with a particle size of 1-5 microns (the mass ratio of PVDF, acetone, and titanium dioxide is 10:100:1), stir at 550 rpm for 2.5 h, and obtain a daytime passive radiation coating dispersion (coating with passive radiation cooling function) after uniform stirring;

[0087] (2) Pour the daytime passive radiation coating dispersion into a spray gun, spray it on the surface of the glass fabric at a pressure of 0.3-0.6 MPa using a nozzle with a diameter of 0.5 mm, dry at room temperature, and obtain the coating textile with passive radiation cooling function after the solvent is completely volatilized;

[0088] The coating textile with passive radiation cooling function prepared in the present comparative example has a coating thickness of 300 microns; the solar reflectance of the coating textile is 0.91, and the atmospheric window emissivity is 0.90.

[0089] Comparative Example 3

[0090] The surface of the glass fabric is not treated.

[0091] Performance test result analysis:

[0092] Figure 2 And Figure 3 The SEM images of the surface and internal morphology of the coating textile prepared in Example 1 are shown in Figs. 1 and 2, respectively. Figure 2 And 3 As can be seen from Figs. 1 and 2, the radiation refrigeration layer formed on the surface of the glass fabric (including the inside and surface of the radiation refrigeration layer) has a chaotic nano-porous structure. As can be seen from Figs. 1 and 2, Figure 2 It can also be seen that the surface of the coating textile is rough. The rough surface structure and low surface energy promote the hydrophobicity of the passive radiation cooling function coating textile to reach superhydrophobicity (water droplet contact angle of 152.4°), which endows the coating fabric with a physical self-cleaning function.

[0093] As shown in Fig. 3, the water droplet contact angle of the surface of the coating textile prepared in Example 1 is 152.4°, indicating that the coating textile has good hydrophobicity. Figure 4 The immersion states of different pollutants on the surface of the coating textile prepared in Example 1 are shown in Fig. 4. The liquid droplets from left to right and from top to bottom in the figure are dye solution, milk, water, orange juice, coffee, and cola, respectively. Figure 5 The results of Figs. 3 and 4 show that the passive radiation cooling function coating textile prepared in Example 1 can prevent various external pollution and keep the surface clean. Figure 4 5 The results of Figs. 3 and 4 show that the passive radiation cooling function coating textile prepared in Example 1 can prevent various external pollution and keep the surface clean.

[0094] ​Figure 6 Photocatalytic degradation of dye for the coated textile prepared in Example 1. Figure 6 For the state of the coated textile after being dyed by the dye solution, the upper pictures in (c1) and (c2) are the state of the coated textile being infected to present dark color after dark reaction in MB and RhB dye solution, and the lower pictures are the contrast pictures of the coated textile returning to the original state after photocatalysis (lighting for 3h). The comparison results of the upper and lower pictures show that the chemical self-cleaning performance of the coated textile prepared in Example 1 is very excellent. Figure (c3) is the comparison picture of the coated textile after being dyed by oleic acid (OR / OA) before and after chemical self-cleaning, and the oil removal ability of the PVDF / F-TNr (coating with passive radiative cooling function) coating is visually evaluated.

[0095] Figure 7 Antibacterial test results of the coated textile prepared in Example 1, Figure 7 The original sample is the growth condition of the bacterial species without adding the coated textile; no light is the growth condition of the bacterial species after adding the coated textile without lighting; after lighting is the growth condition of the bacterial species after adding the coated textile and lighting. From Figure 7 It can be seen that the coated textile has very excellent antibacterial effect under ultraviolet light, and the inhibition rates of Escherichia coli and Staphylococcus aureus are about 99%.

[0096] Figure 6 and the experimental results of Figure 7 fully show that the chemical self-cleaning (photocatalysis) effect of the coated textile with passive radiative cooling function prepared in Example 1 is remarkable.

[0097] Among them, the bacteriostasis experiment refers to the requirements of GB / T30706–2014, and Escherichia coli and Staphylococcus aureus are used as test bacteria to evaluate the photocatalytic antibacterial performance of the sample.

[0098] The photocatalytic degradation experiment process is as follows: the light source is a 500W mercury lamp (Shanghai Jiguang Special Lighting Appliance Factory). 5*5cm PVDF / F-TNr coated glass fiber fabric is added into 50ml MB solution. After 30min reaction in the dark, the mixture is irradiated under ultraviolet light for 0min, 1h, 2h and 3h, and then the coated fabric is taken out for photography, and the color change is recorded.

[0099] Figure 8 , Figure 9 The reflectivity and emissivity characterization diagrams of the coated textile with passive radiative cooling function obtained in Example 1 are shown in Figure 8 and 9 It can be seen that it shows good reflectivity and emissivity.

[0100] Figure 10The reflectivity characterization comparison chart of the daytime passive radiation coating textile prepared in Example 1, Comparative Examples 1 and 2. From Figure 10 It can be seen that the coating textile prepared in Example 1 has excellent reflectivity compared with the coating textiles prepared in Comparative Examples 1 and 2.

[0101] Figure 11 The temperature test comparison of the coating textile prepared in Example 1 and the glass fabric in Comparative Example 3. From Figure 11 It can be seen that the coating textile prepared in Example 1 can reduce the temperature by 6.2℃ under daytime sunlight compared with the ordinary glass fabric (Comparative Example 3), and has excellent passive cooling performance.

[0102] The biggest advantage of the embodiment of the present application is that the raw materials for preparing the coating textile in the above embodiment are all cheap organic polymers, the amount of inorganic fillers added is small, and the preparation process is simple. The above radiation cooling layer has a porous structure, fully utilizes the hydrophobicity and photocatalytic performance of the inorganic fillers, so that the coating textile has excellent self-cleaning performance; in addition, the synergistic effect of the inorganic fillers and the pores increases the reflectivity to sunlight.

[0103] The above describes the embodiments of the present application in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made according to the purpose of the invention and creation of the present application. Any modification, supplement and equivalent replacement, etc. made within the principle range of the present application shall be included in the protection scope of the present application.

Claims

1. A coating with passive radiation cooling function, characterized in that: The coating with passive radiation cooling function is prepared from radiation cooling layer material, organic solvent and rod-shaped titanium dioxide; Wherein, the radiation cooling layer material is polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polydimethylsiloxane or polymethyl methacrylate; The organic solvent is a mixture of acetone and ethyl acetate.

2. The coating with passive radiation cooling function according to claim 1, characterized in that: The mass ratio of the radiation cooling layer material to acetone is 1:(7-10); In organic solvents, the mass ratio of acetone to ethyl acetate is (5-15):1; The mass ratio of the radiation cooling layer material to the rod-shaped titanium dioxide is 10:(0.5~3).

3. The coating with passive radiation cooling function according to claim 1, characterized in that: The rod-shaped titanium dioxide is prepared by the following method: The photocatalytic titanium dioxide and the infrared reflective titanium dioxide are stirred and mixed with a sodium hydroxide solution, and then transferred to a high-pressure reactor for reaction. After the reaction is completed, the pH is adjusted to 1.5, and the mixture is washed, dried, and calcined to obtain the rod-shaped titanium dioxide.

4. The coating with passive radiation cooling function according to claim 3, characterized in that: The mass ratio of photocatalytic titanium dioxide to infrared reflective titanium dioxide is 1: (1-5); The mass volume ratio of the total amount of titanium dioxide to the sodium hydroxide solution is 1: (50~80) g / mL.

5. The coating with passive radiation cooling function according to claim 3, characterized in that: The reaction temperature in the high-pressure reactor is 150-200°C, and the reaction time is 15-30 hours; The calcination temperature is 400~800 ℃, and the calcination time is 1~4 h.

6. The coating with passive radiation cooling function according to claim 3, characterized in that: The obtained rod-shaped titanium dioxide is hydrophobically modified using 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, and the modified rod-shaped titanium dioxide is used for the preparation of subsequent coatings.

7. The coating with passive radiation cooling function according to claim 6, characterized in that: The mass ratio of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane to rod-shaped titanium dioxide is 1: (1~3).

8. A method for preparing a coating having a passive radiation cooling function according to any one of claims 1 to 7, characterized in that: The radiation cooling layer material is dissolved in an organic solvent, and then rod-shaped titanium dioxide is added and stirred evenly to obtain the coating with the passive radiation cooling function.

9. A method for preparing a passive radiation cooling functional coated textile with self-cleaning properties, characterized in that: Under a pressure of 0.3 to 0.6 MPa, the coating with passive radiation cooling function according to any one of claims 1 to 7 is sprayed onto the surface of a textile substrate, dried at room temperature, and the solvent is completely evaporated to obtain the passive radiation cooling function coated textile with self-cleaning performance.

10. A passive radiative cooling functional coated textile with self-cleaning properties, characterized in that: The method according to claim 9 is used to prepare the compound.

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