High-transmittance radiation refrigeration coating and preparation method thereof

Abstract

The invention discloses a high-transmittance radiation refrigeration coating and a preparation method, and the transparent radiation refrigeration coating is of a three-dimensional ordered porous structure and is prepared by a template method. The high-permeability radiation refrigeration coating with a three-dimensional structure is realized in the preparation process by using the microsphere array with the opal structure, the temperature of a three-dimensional ordered macroporous film radiation refrigeration coating sample is 1.8 K lower than that of a substrate material and 7.8 K lower than the environment temperature, and good radiation refrigeration performance is embodied.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation refrigeration materials, and in particular to a high-transmittance radiation refrigeration coating and a preparation method thereof. Background Art

[0002] Radiative cooling technology uses special materials to radiate heat into space in the infrared band of 8 to 13 microns. This band happens to be the atmospheric window, which allows heat to be dissipated directly through the atmosphere to outer space, thereby achieving cooling. According to Planck's law, the power density of thermal radiation emitted by an object is proportional to the fourth power of the surface temperature of the object, proportional to the surface emissivity of the object, and inversely proportional to the wavelength of the electromagnetic wave emitted by the surface of the object. Therefore, the higher the temperature, the greater the emissivity, and the shorter the wavelength, the stronger the thermal radiation emitted by the object. By selecting suitable materials, one can radiate its own heat to outer space through the atmospheric transparent window in the infrared light range without absorbing too much heat from the sun.

[0003] At present, the general idea of ​​reducing light absorption in the visible light region is to prepare a coating with high emissivity or low absorptivity at the atmospheric window, so the surface of such coating materials is mainly white and opaque. In addition, the white radiation cooling materials prepared by the existing technology are basically two-dimensional structural materials, which are prepared by mechanically superimposing or combining different coatings, and it is impossible to improve the reflectivity of visible light from the material structure itself to reduce heat absorption.

[0004] Therefore, how to prepare a high-transmittance radiation cooling material to improve the reflectivity of visible light from the material structure itself to reduce heat absorption is a problem that needs to be solved urgently. Summary of the invention

[0005] The present invention aims to solve the problem that the current design of radiation cooling materials mainly achieves low light absorption through high reflectivity, resulting in the material itself being usually white and opaque.

[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0007] A highly transparent radiation cooling coating, wherein the transparent radiation cooling coating structure is a three-dimensional ordered pore structure and is prepared by a template method.

[0008] One aspect of the present invention provides a method for preparing a high-transmittance radiation cooling coating, which adopts a drop coating method and comprises the following steps:

[0009] Step 1: Clean the substrate;

[0010] Step 2: preparing a monodisperse polymer microsphere solution of a certain concentration and subjecting it to ultrasonic treatment; the solvent of the solution includes water and / or anhydrous ethanol.

[0011] Step 3: preparing and diluting silica sol gel; the volume ratio of the dilution solvent to the silica sol gel is 1:10-1000, and the dilution solvent can be deionized water;

[0012] Step 4: Take appropriate amounts of the polymer microsphere solution in step 2 and the diluted silica sol gel in step 3 in a certain proportion and stir them evenly to obtain a mixed solution; the volume ratio of the polymer microsphere solution to the diluted silica sol gel is 1:1-10.

[0013] Step 5: drop-coat the mixed solution of step 4 on the surface of the substrate described in step 1, remove the polymer microspheres after natural drying to obtain a high-transmittance radiation cooling coating.

[0014] Furthermore, the dispersibility of the polymer microspheres is lower than 0.1, the mass percentage concentration of the polymer microsphere solution is 1%-5%, the particle size of the polymer microspheres is 100-1000nm, and the ultrasound is applied for 30-50 minutes.

[0015] Furthermore, in step 3, the specific steps include: first preparing a mixed solution of anhydrous ethanol and hydrochloric acid, stirring evenly and then adding the silicon oxide solution dropwise, stirring until a gel is formed for later use; the volume ratio of anhydrous ethanol to hydrochloric acid in the mixed solution is 5-2:1, and the concentration of hydrochloric acid is 0.1 mol / L.

[0016] Furthermore, in step 4, the stirring time is 30-60 min.

[0017] Furthermore, in step 5, the heating temperature is 450-550° C. and the heating time is 1-2 hours.

[0018] The present invention also provides a method for preparing a high-transmittance radiation cooling coating, which adopts a plasma enhanced chemical vapor deposition method and comprises the following steps:

[0019] Step 1: Clean the substrate;

[0020] Step 2: prepare a polymer microsphere solution of a certain concentration and perform ultrasonic treatment, then apply a certain amount of the polymer microsphere solution to the surface of the substrate in step 1 and dry it to obtain a substrate with a polymer microsphere film;

[0021] Step 3: depositing silicon oxide on the substrate with the polymer microsphere film in step 2 by plasma vapor deposition;

[0022] Step 4: After the plasma vapor deposition is completed, the polymer microspheres in the silicon oxide film are removed at high temperature to obtain a high-transmittance radiation cooling coating.

[0023] Furthermore, in step 2, the amount of the polystyrene microsphere solution is 0.4-1 mL, and the drying temperature is 30-40°C.

[0024] Furthermore, in step 2, the dispersibility of the polymer microspheres is lower than 0.1, the mass percentage concentration of the polymer microsphere solution is 1%-5%, and the particle size of the polymer microspheres is 100nm-1000nm; the solvent is a mixture of water and anhydrous ethanol, and the volume ratio of water to anhydrous ethanol is 1:5-5:1.

[0025] Furthermore, in step 3, the deposition power is 10-60 W, and the deposition time is 10-60 min.

[0026] It should be noted that the substrate used in the template method includes but is not limited to quartz glass or metal substrate, and the polymer microspheres used include but are not limited to polystyrene and polymethyl methacrylate.

[0027] The present invention has the following beneficial effects:

[0028] 1. The present invention realizes a high-transmittance radiation cooling coating with a three-dimensional structure during the preparation process by using a polymer microsphere array with an opal structure.

[0029] 2. The temperature of the three-dimensional ordered macroporous thin film radiation cooling coating sample of the present invention is still 1.8K lower than that of the base material and 7.8K lower than the ambient temperature, reflecting good radiation cooling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of sample testing;

[0031] Figure 2 This is a sample performance test result diagram;

[0032] Figure 3 These are microscopic pictures of the samples. Figure a shows the microscopic morphology of arranged polystyrene balls; Figure b shows the microscopic morphology of vapor-deposited silicon oxide on the polystyrene microsphere substrate; Figures c and d show the three-dimensional ordered macroporous structure formed after high-temperature removal of the polystyrene microspheres. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Example 1

[0036] The preparation method is as follows:

[0037] (1) cleaning quartz glass and testing its hydrophilicity; (2) preparing a solution of polymer microspheres with a mass percentage concentration of 1% and a particle size of 100, wherein the dispersibility of the polymer microspheres is less than 0.1, and the solvent of the solution can be water or anhydrous ethanol, or a mixed solution of water and anhydrous ethanol, and placing it in an ultrasonic cleaner for ultrasonication for 30 minutes to make it mixed and dispersed uniformly; (3) preparing an acidic sol-gel of silicon oxide material, wherein the volume ratio of anhydrous ethanol to hydrochloric acid is 5:1, and the concentration of hydrochloric acid is 0.1 mol / L, and after stirring evenly, an appropriate amount of silicon oxide solution is added dropwise, and stirring is continued for 1 hour, and a gel is formed and then used for use; (4) diluting the prepared silica gel with deionized water, wherein the volume ratio of the dilution solvent to the silica sol gel is 1:10; (5) taking appropriate amounts of the polymer microsphere solution and the diluted silica gel in a certain proportion, stirring them evenly to obtain a mixed solution, wherein the volume ratio of the polymer microsphere solution to the diluted silica sol gel is 1:1, and the stirring time is 30 minutes; (6) taking a certain amount of the mixed solution and evenly dropping it on the treated substrate surface, and drying it naturally; (7) in an air atmosphere, heating the sample to 450°C and keeping it warm for 1 hour, the polymer microspheres can be removed to obtain a three-dimensional structured high-transmittance radiation cooling coating.

[0038] Example 2

[0039] The preparation method is as follows:

[0040] (1) cleaning the metal substrate and testing its hydrophilicity; (2) preparing a solution of polymer microspheres with a mass percentage concentration of 5% and a particle size of 1000 nm, wherein the dispersibility of the polymer microspheres is less than 0.1, and the solvent of the solution can be water or anhydrous ethanol, or a mixed solution of water and anhydrous ethanol, and placing it in an ultrasonic cleaner for ultrasonication for 50 minutes to make it mixed and dispersed uniformly; (3) preparing an acidic sol-gel of silicon oxide material, wherein the volume ratio of anhydrous ethanol to hydrochloric acid is 2:1, and the concentration of hydrochloric acid is 0.1 mol / L, and after stirring evenly, an appropriate amount of silicon oxide solution is added dropwise, and stirring is continued for 2 hours, and a gel is formed and then used for use; 4) diluting the prepared silica gel with deionized water, wherein the volume ratio of the dilution solvent to the silica sol gel is 1:1000; (5) taking appropriate amounts of polymer microsphere solution and diluted silica gel in a certain proportion, stirring them evenly to obtain a mixed solution, wherein the volume ratio of the polymer microsphere solution to the diluted silica sol gel is 1:10, and the stirring time is 60 minutes; (6) taking a certain amount of the mixed solution and evenly dropping it on the treated substrate surface, and drying it naturally; (7) in an air atmosphere, heating the sample to 550°C and keeping it warm for 2 hours, the polymer microspheres can be removed to obtain a three-dimensional structured high-transmittance radiation cooling coating.

[0041] Example 3

[0042] The preparation method is plasma enhanced chemical vapor deposition, and the specific preparation method is as follows:

[0043] (1) Cleaning quartz glass and testing its hydrophilicity; (2) Preparing a monodisperse solution of polymer microspheres with a mass percentage concentration of 1% and a particle size of 100 nm, wherein the dispersibility of the polymer microspheres is less than 0.1, and the solvent is a mixture of water and anhydrous ethanol, and the volume ratio of water to anhydrous ethanol is 1:5, and then placing it in an ultrasonic cleaner for ultrasonic cleaning for 30 minutes; (3) Applying 0.4 mL of the monodisperse polymer microsphere solution dropwise to the surface of the substrate, and drying it at 30°C for standby use; (4) Placing the substrate with the polymer microsphere film in a plasma vapor deposition chamber to deposit silicon oxide material, wherein the power during the deposition process is about 10 W, the deposition time is 10 minutes, and the particle size of the polymer microspheres after deposition is about 120-150% of the original particle size; (5) After the plasma vapor deposition is completed, the polymer microspheres in the silicon oxide film are removed from the coated substrate at high temperature to obtain a three-dimensional structured high-transmittance radiation cooling coating.

[0044] Example 4

[0045] The preparation method is plasma enhanced chemical vapor deposition, and the specific preparation method is as follows:

[0046] (1) Cleaning the metal substrate and testing its hydrophilicity; (2) Preparing a monodisperse solution of polymer microspheres with a mass percentage concentration of 5% and a particle size of 1000 nm, wherein the dispersibility of the polymer microspheres is less than 0.1, and the solvent is a mixture of water and anhydrous ethanol, and the volume ratio of water to anhydrous ethanol is 5:1, and then placing it in an ultrasonic cleaner for ultrasonic cleaning for 60 minutes; (3) Applying 1 mL of the monodisperse polymer microsphere solution dropwise to the surface of the substrate, and drying it at 40°C for standby use; (4) Placing the substrate with the polymer microsphere film in a plasma vapor deposition chamber to deposit silicon oxide material, wherein the power during the deposition process is about 60 W, the deposition time is 60 minutes, and the particle size of the polymer microspheres after deposition is about 120-150% of the original particle size; (5) After the plasma vapor deposition is completed, the polymer microspheres in the silicon oxide film are removed from the coated substrate at high temperature to obtain a three-dimensional structured high-transmittance radiation cooling coating.

[0047] like Figure 1 The following is a sample test schematic diagram. The specific test method is as follows: a test device is made of polystyrene foam, the outer surface is covered with a layer of aluminum foil to reflect solar radiation, and the upper surface is sealed with PE film to reduce the influence of external air convection. A thermocouple is used to test the surface temperature of the sample. During the test, an optical power meter and a temperature and humidity meter are used to record the intensity of solar radiation and the changes in temperature and humidity in real time.

[0048] Figure 2 Figure 1 is a sample performance test result diagram. Figure A is the sample and ambient temperature test result. After sunset at 18:00, there is still a temperature difference of 6.8K between the sample and the ambient temperature. In the entire test stage, the radiation cooling sample prepared by this method is always lower than the ambient temperature, showing good and stable refrigeration capacity. Figure B is the radiation cooling test result of the radiation cooling sample, ambient temperature and pure aluminum sheet. During the daytime solar irradiation period, the pure aluminum sheet as a metal material quickly absorbs heat and heats up, and the maximum temperature can reach 70°C, while the temperature difference between the sample and the ambient temperature remains at 7-9K. After sunset, there is no sunlight radiation at night, and the temperature of the pure aluminum sheet begins to drop, and eventually drops below the ambient temperature. There is a temperature difference of 6K between the pure aluminum sheet and the ambient temperature. The temperature of the three-dimensional ordered macroporous film radiation cooling sample obtained by the present invention is still 1.8K lower than that of the pure aluminum sheet and 7.8K lower than the ambient temperature, reflecting good radiation cooling performance.

[0049] Figure 3 These are microscopic pictures of the samples. Figure a shows the microscopic morphology obtained after a uniformly mixed polystyrene microsphere solution is drop-coated on a glass and metal substrate. The polystyrene microspheres are neatly stacked and arranged on the substrate surface. Figure b shows the microstructure after silicon oxide is deposited on the polystyrene microsphere layer. The deposited silicon oxide is distributed in the gaps between the polystyrene microspheres. Figures c and d show the three-dimensional ordered macroporous structures formed after removing the polystyrene microspheres at high temperature.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0051] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A high-transmittance radiation cooling coating, characterized in that: The transparent radiation cooling coating structure is a three-dimensional ordered pore structure, which is prepared by a template method.

2. A method for preparing a high-transmittance radiation cooling coating, characterized in that: The drip coating method includes the following steps: Step 1: Clean the substrate; Step 2: preparing a polymer microsphere solution of a certain concentration and ultrasonically treating it; Step 3: preparing and diluting a silica sol gel; the volume ratio of the dilution solvent to the silica sol gel is 1:10-1000; Step 4: taking appropriate amounts of the polymer microsphere solution in step 2 and the diluted silica sol gel in step 3 in a certain proportion, stirring them evenly to obtain a mixed solution; the volume ratio of the polymer microsphere solution to the diluted silica sol gel is 1:1-10; Step 5: drop-coat the mixed solution of step 4 on the surface of the substrate described in step 1, remove the polymer microspheres after natural drying to obtain a high-transmittance radiation cooling coating.

3. The method for preparing a high-transmittance radiation cooling coating according to claim 2, characterized in that: In step 2, the dispersibility of the polymer microspheres is lower than 0.1, the mass percentage concentration of the polymer microsphere solution is 1%-5%, the particle size of the polymer microspheres is 100-1000 nm, and the ultrasound is applied for 30-50 minutes.

4. The method for preparing a high-transmittance radiation cooling coating according to claim 2, characterized in that: In step 3, the specific steps include: first preparing a mixed solution of anhydrous ethanol and hydrochloric acid, stirring evenly, adding the silicon oxide solution dropwise, and stirring until a gel is formed for later use; the volume ratio of anhydrous ethanol to hydrochloric acid in the mixed solution is 5-2:

1.

5. The method for preparing a high-transmittance radiation cooling coating according to claim 2, characterized in that: In step 4, the stirring time is 30-60 min.

6. The method for preparing a high-transmittance radiation cooling coating according to claim 2, characterized in that: In step 5, the heating temperature is 450-550° C. and the temperature is kept for 1-2 hours.

7. A method for preparing a high-transmittance radiation cooling coating, characterized in that: The plasma enhanced chemical vapor deposition method includes the following steps: Step 1: Clean the substrate; Step 2: prepare a polymer microsphere solution of a certain concentration and perform ultrasonic treatment, then apply a certain amount of the polymer microsphere solution to the surface of the substrate in step 1 and dry it to obtain a substrate with a polymer microsphere film; Step 3: depositing silicon oxide on the substrate with the polymer microsphere film in step 2 by plasma enhanced chemical vapor deposition; Step 4: After the plasma vapor deposition is completed, the polymer microspheres in the silicon oxide film are removed at high temperature to obtain a high-transmittance radiation cooling coating.

8. The method for preparing a high-transmittance radiation cooling coating according to claim 7, characterized in that: In the step 2, the amount of the polystyrene microsphere solution is 0.4-1 mL, and the drying temperature is 30-40°C.

9. The method for preparing a high-transmittance radiation cooling coating according to claim 8, characterized in that: In step 2, the dispersibility of the polymer microspheres is lower than 0.1, the mass percentage concentration of the polymer microsphere solution is 1%-5%, and the particle size of the polymer microspheres is 100nm-1000nm; the solvent is a mixture of water and anhydrous ethanol, and the volume ratio of water to anhydrous ethanol is 1:5-5:

1.

10. The method for preparing a high-transmittance radiation cooling coating according to claim 8, characterized in that: In step 3, the deposition power is 10-60 W, and the deposition time is 10-60 min.

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