Thin film with overheating equipment cooling function and preparation method thereof

Abstract

The invention discloses a preparation method of a thin film with an overheating equipment cooling function. The preparation method comprises the following steps: carrying out ball milling on inorganic powder and hexagonal boron nitride to obtain inorganic mixed powder; modifying the inorganic mixed powder by adopting a silane coupling agent aqueous solution and a phosphoric acid aqueous solution to obtain modified inorganic mixed powder; adding a polymer into an organic solvent, dissolving to obtain a polymer-based solution, then adding the modified inorganic mixed powder for self-assembly, and pouring into a mold for vacuum drying to obtain a flexible film; and adding the photoluminescence pigment and titanium dioxide into polydimethylsiloxane, a curing agent and normal hexane, stirring for reaction, spraying to the surface of the flexible film, and curing to obtain the film with the overheating equipment cooling function. Efficient cooling of overheating equipment is achieved, the problems that an existing refrigeration film is poor in high heat resistance, cooling performance, flexibility and mechanical performance, not prone to large-scale production, low in aesthetic requirement during use and the like are solved, and good application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of power or overheating equipment cooling technology, and more specifically, this invention relates to a thin film with overheating equipment cooling function and its preparation method. Background Technology

[0002] Radiative cooling, as a zero-energy cooling strategy, is widely used in aerospace, textiles, construction, and food industries. On the other hand, with the development of artificial intelligence, electronic components such as semiconductors will inevitably evolve towards higher power and computing power. However, data centers generate a large amount of heat during operation, which not only affects equipment performance but can also lead to hardware failures. Therefore, compared to cooling conventional objects, the heat dissipation problem of objects above ambient temperature is more urgent.

[0003] There are three basic modes of heat transfer: conduction, convection, and radiation. For high-temperature devices indoors, heat flux is negligible, and air has extremely low thermal conductivity; therefore, passive cooling solutions often rely solely on radiation. Compared to traditional selective emitters, broadband emitters offer significant advantages in cooling objects at temperatures above ambient. However, traditional radiative cooling materials are porous and have low thermal conductivity, which greatly increases their thermal resistance, hindering cooling at temperatures above ambient. Therefore, achieving materials with both high broadband emission and high thermal conductivity in the mid-infrared region is crucial for solving the heat dissipation problem.

[0004] For outdoor equipment, the impact of solar radiation must be considered, and we need to reflect as much sunlight as possible. At the same time, the aesthetic appeal of the materials must also be taken into account; ensuring both high solar reflectivity and color coexistence is a challenging problem in this field. Furthermore, excellent mechanical properties and durability are also crucial for the application of these materials. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] To achieve these objectives and other advantages of the present invention, a method for preparing a thin film with a cooling function for overheated equipment is provided, comprising the following steps: Step 1: Ball mill and mix the inorganic powder and hexagonal boron nitride to obtain an inorganic mixed powder; Step 2: Add phosphoric acid aqueous solution dropwise to the silane coupling agent aqueous solution, mix well, then add the inorganic mixed powder from Step 1, react for 5-7 hours, centrifuge and dry to obtain the modified inorganic mixed powder; Step 3: Add the polymer to the organic solvent, mix evenly, and dissolve to obtain a polymer-based solution; add the modified inorganic mixed powder from Step 2 to the polymer-based solution for self-assembly, then pour it into a mold and vacuum dry to obtain a flexible film; Step 4: Add photoluminescent pigment and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent and n-hexane, mix evenly, stir to react, spray the resulting reaction solution onto the surface of the flexible film in Step 3, and cure to obtain a film with the function of cooling overheated equipment.

[0007] Preferably, in step 1, the inorganic powder is one or more of silicon dioxide, calcium carbonate, aluminum phosphate, and titanium dioxide; the mass ratio of the inorganic powder to hexagonal boron nitride is 1:1 to 10; and the ball milling time is 4 to 16 hours.

[0008] Preferably, in step 2, the silane coupling agent is one or more of KH-550 (γ-aminopropyltriethoxysilane), KH-792 (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), KH-570 (γ-(methacryloyloxy)propyltrimethoxysilane), and KH-560 (γ-glycidoxypropyltrimethoxysilane).

[0009] Preferably, in step 2, the concentration of the silane coupling agent aqueous solution is 0.1~0.4 mol / L; and the concentration of the phosphoric acid aqueous solution is 0.1~0.6 mol / L.

[0010] Preferably, the chemical structural formula of the silane coupling agent is as follows: ; Among them, formula (A) is KH-550; formula (B) is KH-792; formula (C) is KH-570; and formula (D) is KH-560.

[0011] Preferably, in step 2, the molar ratio of silane coupling agent to phosphoric acid is 1~2:0.5~3; and the mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:1~5.

[0012] Preferably, in step 3, the organic solvent is an alkaline dimethyl sulfoxide solution or tetrahydrofuran; the polymer is one or more of Kevlar fiber (Kevlar 49), polymethyl methacrylate and polyurethane.

[0013] Preferably, in step 3, the mass ratio of polymer to organic solvent is 1:10~100; the mass ratio of polymer to modified inorganic mixed powder is 1:0.1~2.

[0014] Preferably, in step 4, the photoluminescent pigment is (Ba,Sr)₂SiO₄:Eu2+ Y3Al5O 12 :Ce 3+ or SrAlSiN3:Eu 2+ The curing agent is Dow Corning SYLGARD 184 part B; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5~2:0.05~0.2:10~30.

[0015] Preferably, in step 4, the stirring reaction temperature is 30~70℃, the time is 2~5h, and the curing temperature is 50~100℃.

[0016] Preferably, in step 4, the spraying amount is 50~100ml / m 2 The thickness of the resulting film with cooling function for overheated equipment is 150~250µm.

[0017] A thin film with a cooling function for overheated equipment, prepared by the method described above.

[0018] The present invention has at least the following beneficial effects: (1) The thin film with overheating equipment cooling function of the present invention has excellent reflectivity and broadband emissivity, high solar reflectivity and high emissivity in the mid-infrared region; (2) The thin film with the function of cooling the overheating equipment of the present invention does not have a porous structure. This unique non-porous structure results in the final thin film having a high thermal conductivity, which reaches 0.89 W / m K. (3) The film with the function of cooling overheated equipment of the present invention has a thickness of only 200 µm, and can cool down indoors by up to 16.4 °C and outdoors by up to 28.9 °C; (4) The thin film with the function of cooling the overheating equipment of the present invention does not have a porous structure, which ensures a high thermal conductivity. At the same time, the stress dispersion greatly enhances the mechanical properties of the material, solving the problem of insufficient mechanical properties caused by porous structures in the existing research. (5) The thin film prepared by the present invention is coated with a single layer of colored fluorescent material, which greatly satisfies people's requirements for material aesthetics and can improve the cooling performance of the thin film. In addition, the unique photoluminescence effect of the fluorescent material makes it more suitable for practical use. (6) The thin film of the present invention with the function of cooling overheated equipment has excellent reflectivity, broadband emission performance, thermal conductivity and thin thickness. In addition, the film has a unique color effect, which makes it have a very wide range of applications in the field of cooling heat-generating objects such as electronic components and factory equipment. (7) The preparation method of the present invention is simple and suitable for large-scale preparation. It realizes efficient cooling of overheated equipment and solves the problems of high thermal resistance, poor cooling performance, flexibility and mechanical properties, difficulty in large-scale production and aesthetic requirements in actual use of current refrigeration films. It has good application prospects in cooling indoor and outdoor overheated equipment.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0020] Figure 1 The image shows the optical properties of the thin film with overheating equipment cooling function prepared in Example 16 of this invention; in the image, the 0.3 ~ 2.5 µm region is the solar reflectivity, the 2.5 ~ 25 µm region is the emissivity in the mid-infrared region, and the 8 ~ 13 µm region is the emissivity of the atmospheric window. Figure 2 A scanning electron microscope image of the surface of the thin film with overheating equipment cooling function prepared in Embodiment 15 of the present invention; Figure 3 Tensile properties of the thin film with overheating equipment cooling function prepared in Example 16 of the present invention and the porous thin film prepared in Comparative Example 1; Figure 4 Photographs of the thin films with overheating equipment cooling function prepared in Examples 15, 16 and 30 of the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0022] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0023] In the following examples, the curing agent used was Dow Corning SYLGARD 184 part B; the alkaline dimethyl sulfoxide solution used was obtained by mixing dimethyl sulfoxide and KOH in a mass ratio of 100:1.

[0024] Example 1 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica and hexagonal boron nitride are ball-milled for 4 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica to hexagonal boron nitride is 1:1. Step 2: Add 0.1 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 2:0.5; the silane coupling agent is KH-550. Step 3: Add Kevlar fiber (Kevlar 49) to an alkaline dimethyl sulfoxide solution and mix thoroughly. The mass ratio of alkaline dimethyl sulfoxide solution to Kevlar fiber is 100:1. After complete dissolution, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of Kevlar fiber to modified inorganic mixed powder is 1:1. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 30 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 50 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5:0.05:10.

[0025] Example 2 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Calcium carbonate and hexagonal boron nitride are ball-milled for 6 hours to obtain an inorganic mixed powder; wherein the mass ratio of calcium carbonate to hexagonal boron nitride is 1:2. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 2:1; the silane coupling agent is KH-792. Step 3: Add Kevlar fiber (Kevlar 49) to an alkaline dimethyl sulfoxide solution and mix thoroughly. The mass ratio of alkaline dimethyl sulfoxide solution to Kevlar fiber is 100:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of Kevlar fiber to modified inorganic mixed powder is 1:0.1. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 35 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 60 ml / m². 2 Finally, curing at 80 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:20.

[0026] Example 3 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Aluminum phosphate and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of aluminum phosphate to hexagonal boron nitride is 1:3. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution dropwise to 0.4 mol / L silane coupling agent aqueous solution, mix well, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 2:1.5; the silane coupling agent is KH-570. Step 3: Add polymethyl methacrylate and polyurethane to tetrahydrofuran, mix thoroughly, with a mass ratio of tetrahydrofuran, polymethyl methacrylate and polyurethane of 100:5:5, and dissolve completely to obtain a polymer-based solution; add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; wherein the mass ratio of polymer (polymethyl methacrylate and polyurethane) to modified inorganic mixed powder is 1:0.5, then pour into a mold and vacuum dry to obtain a flexible film; Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, curing at 60 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:30.

[0027] Example 4 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:5. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-560. Step 3: Add Kevlar fiber (Kevlar 49) and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, with the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polyurethane being 100:0.5:0.5, and obtain a polymer-based solution after complete dissolution; add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; wherein the mass ratio of polymer (Kevlar fiber and polyurethane) to modified inorganic mixed powder is 1:1, then pour into a mold and vacuum dry to obtain a flexible film; Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 45 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 65 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1.5:0.15:20.

[0028] Example 5 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Calcium carbonate and hexagonal boron nitride are ball-milled for 12 hours to obtain an inorganic mixed powder; wherein the mass ratio of calcium carbonate to hexagonal boron nitride is 1:6. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution dropwise to 0.2 mol / L silane coupling agent aqueous solution, mix well, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-550 and KH-560 (molar ratio 1:1). Step 3: Add Kevlar fiber (Kevlar 49) and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, with the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polyurethane being 100:0.5:0.5, and obtain a polymer-based solution after complete dissolution; add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; wherein the mass ratio of polymer (Kevlar fiber and polyurethane) to modified inorganic mixed powder is 1:1, then pour into a mold and vacuum dry to obtain a flexible film; Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of curing agent and n-hexane, mix thoroughly, and react at 50 °C for 4 h under stirring. Then spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:30.

[0029] Example 6 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 16 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.4 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 0.5:1; the silane coupling agents are KH-550 and KH-792 (molar ratio 1:1). Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 55 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, curing at 75 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:10.

[0030] Example 7 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica and hexagonal boron nitride are ball-milled for 4 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica to hexagonal boron nitride is 1:4. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-550 and KH-570 (molar ratio 1:1). Step 3: Add polymethyl methacrylate and polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran, polymethyl methacrylate, and polyurethane is 100:5:5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (polymethyl methacrylate and polyurethane) to modified inorganic mixed powder is 1:1.5. Then, pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 60 °C for 2 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 100 ml / m². 2 Finally, curing at 80 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:30.

[0031] Example 8 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, aluminum phosphate and hexagonal boron nitride are ball-milled for 14 h to obtain an inorganic mixed powder; wherein the mass ratio of silica, aluminum phosphate and hexagonal boron nitride is 0.5:0.5:3. Step 2: Add 0.4 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:2; the silane coupling agents are KH-550, KH-792, and KH-570 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49) to an alkaline dimethyl sulfoxide solution and mix thoroughly. The mass ratio of alkaline dimethyl sulfoxide solution to Kevlar fiber is 100:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of Kevlar fiber to modified inorganic mixed powder is 1:2. Then, pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 60 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 60 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 85 ℃; the mass ratio of the sprayed photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:10.

[0032] Example 9 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:10. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:2; the silane coupling agents are KH-550, KH-560, and KH-792 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49) to an alkaline dimethyl sulfoxide solution and mix thoroughly. The mass ratio of alkaline dimethyl sulfoxide solution to Kevlar fiber is 100:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of Kevlar fiber to modified inorganic mixed powder is 1:0.5. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 60 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, curing at 90 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5:0.05:30.

[0033] Example 10 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Aluminum phosphate, titanium dioxide, and hexagonal boron nitride are ball-milled for 16 hours to obtain an inorganic mixed powder; wherein the mass ratio of aluminum phosphate, titanium dioxide, and hexagonal boron nitride is 0.5:0.5:10. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.15 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:2; the silane coupling agents are KH-792, KH-570, and KH-560 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49) and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber ester, and polyurethane is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polyurethane) to modified inorganic mixed powder is 1:1.5. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 60 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 95 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:15.

[0034] Example 11 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.4 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-550, KH-792, KH-570, and KH-560 (molar ratio 1:1:1:1). Step 3: Add Kevlar fiber (Kevlar 49), polymethyl methacrylate (PMMA), and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and ensure the mass ratio of alkaline DMF solution, Kevlar fiber, PMMA, and polyurethane is 100:0.5:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (Kevlar fiber, PMMA, and polyurethane) to modified inorganic mixed powder is 1:1. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 60 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 100 ℃; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:25.

[0035] Example 12 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, calcium carbonate, titanium dioxide and hexagonal boron nitride are ball-milled for 14 h to obtain an inorganic mixed powder; wherein the mass ratio of silica, calcium carbonate and titanium dioxide is 1:1:1, and the mass ratio of the total mass of silica, calcium carbonate and titanium dioxide to the mass of hexagonal boron nitride is 1:9. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-792. Step 3: Add polymethyl methacrylate and polyurethane to an alkaline dimethyl sulfoxide solution and mix thoroughly. The mass ratio of alkaline dimethyl sulfoxide solution, polymethyl methacrylate, and polyurethane is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (polymethyl methacrylate and polyurethane) to modified inorganic mixed powder is 1:0.5. Then, pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, curing at 60 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1.5:0.15:10.

[0036] Example 13 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Calcium carbonate, aluminum phosphate, and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of calcium carbonate, aluminum phosphate, and hexagonal boron nitride is 0.5:0.5:9. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-560. Step 3: Add Kevlar fiber (Kevlar 49) and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polyurethane is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polyurethane) to modified inorganic mixed powder is 1:2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 65 °C for 2 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 100 ml / m². 2 Finally, curing at 90 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5:0.05:15.

[0037] Example 14 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Calcium carbonate, titanium dioxide, and hexagonal boron nitride are ball-milled for 6 hours to obtain an inorganic mixed powder; the mass ratio of calcium carbonate, titanium dioxide, and hexagonal boron nitride is 0.5:0.5:3. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-570. Step 3: Add Kevlar fiber (Kevlar 49) and polymethyl methacrylate to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polymethyl methacrylate is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polymethyl methacrylate) to modified inorganic mixed powder is 1:2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu)2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 60 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5:0.05:15.

[0038] Example 15 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, calcium carbonate, aluminum phosphate, titanium dioxide, and hexagonal boron nitride are ball-milled for 4 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica, calcium carbonate, aluminum phosphate, and titanium dioxide is 1:1:1:1; and the mass ratio of the total mass of silica, calcium carbonate, aluminum phosphate, and titanium dioxide to the mass of hexagonal boron nitride is 1:10. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:2; the silane coupling agents are KH-570 and KH-560 (molar ratio 1:1). Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.8. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:20.

[0039] Example 16 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:10. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:3; the silane coupling agent is KH-570. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 75 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0040] Example 17 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, titanium dioxide and hexagonal boron nitride are ball-milled for 10 h to obtain an inorganic mixed powder; wherein the mass ratio of silica to titanium dioxide is 1:3, and the mass ratio of the total mass of silica and titanium dioxide to the mass of hexagonal boron nitride is 1:4. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-792, KH-570, and KH-560 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49), polymethyl methacrylate (PMMA), and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and ensure the mass ratio of alkaline DMF solution, Kevlar fiber, PMMA, and polyurethane is 100:0.5:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (Kevlar fiber, PMMA, and polyurethane) to modified inorganic mixed powder is 1:2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, curing at 80 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1.5:0.15:30.

[0041] Example 18 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 h to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-792. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 45 °C for 2 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 100 ml / m². 2 Finally, curing at 85 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:20.

[0042] Example 19 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica and hexagonal boron nitride are ball-milled for 6 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica to hexagonal boron nitride is 1:10. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-792, KH-570, and KH-560 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49) and polymethyl methacrylate to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polymethyl methacrylate is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polymethyl methacrylate) to inorganic mixed powder is 1:0.5. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 55 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, curing at 75 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:30.

[0043] Example 20 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1.5; the silane coupling agents are KH-570 and KH-560 (molar ratio 1:1). Step 3: Add Kevlar fiber (Kevlar 49) and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polyurethane is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polyurethane) to modified inorganic mixed powder is 1:0.2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 30 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 80 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:20.

[0044] Example 21 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, titanium dioxide, and hexagonal boron nitride are ball-milled for 16 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica, titanium dioxide, and hexagonal boron nitride is 0.5:0.5:7. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1.5; the silane coupling agent is KH-570. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 30 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 100 ℃; wherein the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0045] Example 22 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:6. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-792, KH-570, and KH-560 (molar ratio 1:1:1). Step 3: Add Kevlar fiber (Kevlar 49), polymethyl methacrylate (PMMA), and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and ensure the mass ratio of alkaline DMF solution, Kevlar fiber, PMMA, and polyurethane is 100:0.5:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (Kevlar fiber, PMMA, and polyurethane) to modified inorganic mixed powder is 1:2. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 100 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 80 ℃; the mass ratio of the sprayed photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1.5:0.15:30.

[0046] Example 23 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica and hexagonal boron nitride are ball-milled for 4 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica to hexagonal boron nitride is 1:1. Step 2: Add 0.2 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agent is KH-792. Step 3: Add Kevlar fiber (Kevlar 49) and polymethyl methacrylate to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber, and polymethyl methacrylate is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polymethyl methacrylate) to modified inorganic mixed powder is 1:0.8. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 55 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 60 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment, wherein the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0047] Example 24 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Calcium carbonate, aluminum phosphate, and hexagonal boron nitride are ball-milled for 14 hours to obtain an inorganic mixed powder; wherein the mass ratio of calcium carbonate, aluminum phosphate, and hexagonal boron nitride is 0.5:0.5:7. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.3 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue the reaction for 6 hours to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-792 and KH-570 (molar ratio 1:1). Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 2 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 85 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0048] Example 25 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1.5; the silane coupling agent is KH-792. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add titanium dioxide and polydimethylsiloxane to a mixed solution of curing agent and n-hexane, mix thoroughly, and react at 50 °C for 5 h under stirring. Then spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m. 2 Finally, the film with the function of cooling the overheating equipment can be obtained by curing at a temperature of 100 ℃; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:20.

[0049] Example 26 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Aluminum phosphate, titanium dioxide, and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of aluminum phosphate, titanium dioxide, and hexagonal boron nitride is 0.5:0.5:9. Step 2: Add 0.4 mol / L phosphoric acid aqueous solution to a 0.4 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1; the silane coupling agents are KH-550, KH-792, KH-570, and KH-560 (molar ratio 1:1:1:1). Step 3: Add Kevlar fiber (Kevlar 49), polymethyl methacrylate (PMMA), and polyurethane to an alkaline dimethyl sulfoxide solution, mix thoroughly, and ensure the mass ratio of alkaline DMF solution, Kevlar fiber, PMMA, and polyurethane is 100:0.5:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polymer (Kevlar fiber, PMMA, and polyurethane) to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 45 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 100 ml / m². 2 Finally, curing at 65 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:30.

[0050] Example 27 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, calcium carbonate, titanium dioxide, and hexagonal boron nitride are ball-milled for 10 h to obtain an inorganic mixed powder; wherein, the mass ratio of silica, calcium carbonate, and titanium dioxide is 1:1:1, and the mass ratio of the total mass of silica, calcium carbonate, and titanium dioxide to the mass of hexagonal boron nitride is 1:7. Step 2: Add 0.1 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:0.5; the silane coupling agents are KH-570 and KH-560 (molar ratio 1:1). Step 3: Add Kevlar fiber (Kevlar 49) and polymethyl methacrylate to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber, and polymethyl methacrylate is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polymethyl methacrylate) to modified inorganic mixed powder is 1:1.5. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 90 ℃; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:2:0.2:10.

[0051] Example 28 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 10 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1.5; the silane coupling agent is KH-560. Step 3: Add Kevlar fiber (Kevlar 49) and polymethyl methacrylate to an alkaline dimethyl sulfoxide solution, mix thoroughly, and the mass ratio of alkaline dimethyl sulfoxide solution, Kevlar fiber and polymethyl methacrylate is 100:0.5:0.5. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; the mass ratio of polymer (Kevlar fiber and polymethyl methacrylate) to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 95 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:15.

[0052] Example 29 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.1 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:0.5; the silane coupling agent is KH-570. Step 3: Add polymethyl methacrylate and polyurethane to tetrahydrofuran, mix thoroughly, with a mass ratio of tetrahydrofuran, polyurethane, and polyurethane of 100:5:5, and dissolve completely to obtain a polymer-based solution; add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; wherein the mass ratio of polymer (polymethyl methacrylate and polyurethane) to modified inorganic mixed powder is 1:0.7, then pour into a mold and vacuum dry to obtain a flexible film; Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 4 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 90 ml / m². 2 Finally, curing at 85 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0053] Example 30 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:7. Step 2: Add 0.3 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:1.5; the silane coupling agent is KH-550. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 4: Apply the photoluminescent pigment (SrAlSiN3:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 40 °C for 5 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 70 ml / m². 2 Finally, the film with the function of cooling overheated equipment can be obtained by curing at a temperature of 100 ℃; the mass ratio of the sprayed photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0054] Example 31 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Silica, titanium dioxide, and hexagonal boron nitride are ball-milled for 16 hours to obtain an inorganic mixed powder; wherein the mass ratio of silica, titanium dioxide, and hexagonal boron nitride is 0.5:0.5:7. Step 2: Add 0.1 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:0.5; the silane coupling agent is KH-570. Step 3: Add polymethyl methacrylate and polyurethane to tetrahydrofuran, mix thoroughly, with a mass ratio of tetrahydrofuran, polyurethane, and polyurethane of 100:5:5, and dissolve completely to obtain a polymer-based solution; add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly; wherein the mass ratio of polymer (polymethyl methacrylate and polyurethane) to modified inorganic mixed powder is 1:2, then pour into a mold and vacuum dry to obtain a flexible film; Step 4: Apply photoluminescent pigment (Y3Al5O) 12 :Ce 3+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 35 °C for 2 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 70 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:20.

[0055] Comparative Example 1 A method for preparing a porous thin film includes the following steps: Step 1: Add polyurethane to dimethyl sulfoxide, mix well, the mass ratio of dimethyl sulfoxide to polyurethane is 10:1, and the polymer-based solution is obtained after complete dissolution; Step 2: Slowly pour the polymer-based solution from Step 1 into the pre-prepared mold, then place the mold in a water bath at room temperature for 12 hours. After that, remove the film from the mold and vacuum dry it to obtain a porous film with a thickness of 200 μm.

[0056] This comparative example uses a traditional phase separation method to prepare a conventional thin film with a porous structure.

[0057] Comparative Example 2 A method for preparing a flexible thin film includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:10. Step 2: Add 0.6 mol / L phosphoric acid aqueous solution to a 0.2 mol / L silane coupling agent aqueous solution, mix thoroughly, then add the inorganic mixed powder from Step 1, and continue to react for 6 h to obtain a modified suspension. Then centrifuge and dry to obtain the modified inorganic mixed powder. The mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:3; the molar ratio of silane coupling agent to phosphoric acid is 1:3; the silane coupling agent is KH-570. Step 3: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the modified inorganic mixed powder from Step 2 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to modified inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film with a thickness of 200 μm.

[0058] This comparative example differs from Example 16 only in that it does not spray colored fluorescent material.

[0059] Comparative Example 3 A method for preparing a thin film with a cooling function for overheated equipment includes the following steps: Step 1: Titanium dioxide and hexagonal boron nitride are ball-milled for 8 hours to obtain an inorganic mixed powder; wherein the mass ratio of titanium dioxide to hexagonal boron nitride is 1:10. Step 2: Add polyurethane to tetrahydrofuran and mix thoroughly. The mass ratio of tetrahydrofuran to polyurethane is 10:1. Once fully dissolved, a polymer-based solution is obtained. Add the inorganic mixed powder from Step 1 to the above polymer-based solution for self-assembly. The mass ratio of polyurethane to inorganic mixed powder is 1:0.7. Then pour the mixture into a mold and vacuum dry to obtain a flexible film. Step 3: Apply the photoluminescent pigment ((Ba,Sr)2SiO4:Eu) 2+ Add the polydimethylsiloxane and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent, and n-hexane, mix thoroughly, and react at 50 °C for 3 h under stirring. Then, spray the mixture onto the surface of the flexible film obtained in step 3 at a rate of 80 ml / m². 2 Finally, curing at 75 ℃ yields a film with cooling function for overheated equipment; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:1:0.1:10.

[0060] The only difference between this comparative example and Example 16 is that the inorganic mixed powder is not modified.

[0061] The films with overheating equipment cooling function prepared in Examples 1-31, the porous film prepared in Comparative Example 1, and the flexible film prepared in Comparative Example 2 all have a thickness of 200 µm. The test results for their reflectivity, mid-infrared emissivity, atmospheric window emissivity, thermal conductivity, tensile properties, indoor cooling temperature, and outdoor cooling temperature are shown in Table 1. The reflectivity was tested using a PerkinElmer Lambda 1050L microscope; the emissivity was tested using a Thermo Scientific Nicoleti S50 microscope; and the tensile properties were tested using an INSTRON 3366 microscope.

[0062] Figure 1 The image shows the optical properties of the thin film with overheating equipment cooling function prepared in Example 16 of this invention. In the image, the 0.3~2.5 µm region is the solar reflectivity, the 2.5~25 µm region is the emissivity in the mid-infrared region, and the 8~13 µm region is the emissivity in the atmospheric window. It can be seen that its effective reflectivity is as high as 92.5%, the emissivity in the mid-infrared region is as high as 90.5%, and the emissivity in the atmospheric window is as high as 90.6%, exhibiting extremely high reflectivity and broadband emission characteristics.

[0063] Figure 2 The image shows a scanning electron microscope (SEM) image of the surface of the thin film with overheating equipment cooling function prepared in Example 15 of the present invention. It can be seen that the thin film with overheating equipment cooling function prepared in the present invention does not have a porous structure. This unique non-porous structure results in the final thin film having a high thermal conductivity, which is significantly higher than that of the traditional porous thin film in Comparative Example 1.

[0064] Figure 3 The tensile properties of the thin film with overheating equipment cooling function prepared in Example 16 of the present invention and the porous thin film prepared in Comparative Example 1 are shown in the figure. It can be seen that the thin film with overheating equipment cooling function of the present invention does not have a porous structure. Due to the stress dispersion, the mechanical properties of the material are greatly enhanced, which solves the problem of insufficient mechanical properties caused by porous structures in the existing research.

[0065] Figure 4 Photographs of the thin films with overheating equipment cooling function prepared in Examples 15, 16 and 30 of the present invention.

[0066] As shown in Table 1, the ratio of inorganic mixed powder to polymer has a significant impact on the reflectivity of the film, whether or not fluorescent material is sprayed has a significant impact on the emissivity of the film, the type of solvent and the type and ratio of inorganic mixed powder have a significant impact on the thermal conductivity of the film, and the type of solvent and polymer have a significant impact on the tensile properties of the film. The above properties together determine the indoor and outdoor cooling performance of the film. In summary, the films with overheating equipment cooling function prepared in Examples 15, 16 and 30 of this invention have good comprehensive performance.

[0067] Table 1 Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a thin film with a cooling function for overheated equipment, characterized in that, Includes the following steps: Step 1: Ball mill and mix the inorganic powder and hexagonal boron nitride to obtain an inorganic mixed powder; Step 2: Add phosphoric acid aqueous solution dropwise to the silane coupling agent aqueous solution, mix well, then add the inorganic mixed powder from Step 1, react for 5-7 hours, centrifuge and dry to obtain the modified inorganic mixed powder; Step 3: Add the polymer to the organic solvent, mix evenly, and dissolve to obtain a polymer-based solution; add the modified inorganic mixed powder from Step 2 to the polymer-based solution for self-assembly, then pour it into a mold and vacuum dry to obtain a flexible film; Step 4: Add photoluminescent pigment and titanium dioxide to a mixed solution of polydimethylsiloxane, curing agent and n-hexane, mix evenly, stir to react, spray the resulting reaction solution onto the surface of the flexible film in Step 3, and cure to obtain a film with the function of cooling overheated equipment.

2. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 1, the inorganic powder is one or more of silicon dioxide, calcium carbonate, aluminum phosphate, and titanium dioxide; the mass ratio of inorganic powder to hexagonal boron nitride is 1:1~10; and the ball milling time is 4~16h.

3. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 2, the silane coupling agent is one or more of KH-550, KH-792, KH-570, and KH-560; the concentration of the aqueous solution of the silane coupling agent is 0.1~0.4 mol / L; and the concentration of the aqueous solution of phosphoric acid is 0.1~0.6 mol / L.

4. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 2, the molar ratio of silane coupling agent to phosphoric acid is 1~2:0.5~3; the mass ratio of silane coupling agent aqueous solution to inorganic mixed powder is 50:1~5.

5. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 3, the organic solvent is an alkaline dimethyl sulfoxide solution or tetrahydrofuran; the polymer is one or more of Kevlar fiber, polymethyl methacrylate and polyurethane.

6. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 3, the mass ratio of polymer to organic solvent is 1:10~100; the mass ratio of polymer to modified inorganic mixed powder is 1:0.1~2.

7. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 4, the photoluminescent pigment is (Ba,Sr)₂SiO₄:Eu 2+ Y3Al5O 12 :Ce 3+ or SrAlSiN3:Eu 2+ The curing agent is Dow Corning SYLGARD 184 part B; the mass ratio of photoluminescent pigment, titanium dioxide, polydimethylsiloxane, curing agent and n-hexane is 1:1:0.5~2:0.05~0.2:10~30.

8. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 4, the stirring reaction temperature is 30~70℃ and the time is 2~5h; the curing temperature is 50~100℃.

9. The method for preparing a thin film with a cooling function for overheated equipment as described in claim 1, characterized in that, In step 4, the spraying amount is 50~100ml / m 2 The thickness of the resulting film with cooling function for overheated equipment is 150~250µm.

10. A thin film with a cooling function for overheated equipment, prepared by the preparation method according to any one of claims 1-9.

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