Organic composite structure coating capable of realizing passive radiation refrigeration

Abstract

The invention belongs to the technical field of radiation refrigeration materials, and particularly relates to an organic composite structure coating capable of achieving passive radiation refrigeration, and the organic composite structure coating capable of achieving passive radiation refrigeration is prepared through the following specific steps: step one, weighing 6-10 g of PMMA, 8-12 g of BaSO4 and 1-3 g of TiO2, placing the materials in a 50 ml beaker, and continuously stirring the materials for 30-60 s with a stirring rod until the materials are mixed uniformly, a solid mixture is obtained; 2, 30-36 ml of DMF is added into the solid mixture, stirring is conducted for 4 h under the water bath condition of 40-50 DEG C till PMMA is completely dissolved, the system is thick, and the passive radiation refrigeration coating precursor is prepared. The preparation process is simple and efficient, the condition is mild, and large-scale preparation can be achieved; the prepared PMMA / BaSO4 / TiO2 structural coating has a good passive radiation refrigeration effect. In hot summer, a 6 DEG C sub-environment passive radiation refrigeration effect can be realized, and the material has a wide application prospect in the fields of energy conservation, emission reduction and environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of radiation refrigeration materials, in particular to an organic composite structure coating capable of realizing passive radiation refrigeration. Background Art

[0002] Thermal management is of great significance in industrial production and daily life. With the intensification of global warming, the average ambient temperature of the earth continues to rise, which poses unprecedented challenges to the survival and development of organisms. Traditional refrigeration technology usually relies on the compressor to actively drive the refrigerant to achieve the cooling effect. This method not only consumes a lot of energy, but also only plays the role of heat transfer, and fails to effectively solve the fundamental problem of heat generation. In addition, the leakage of refrigerants will lead to the emission of greenhouse gases, further damage the atmosphere, and promote the process of global warming, thus forming a vicious circle. This type of technical model poses a significant threat to environmental protection and human sustainable development. Passive radiation cooling is a new and green cooling method. According to the blackbody radiation law and the mid-infrared atmospheric transmittance, the blackbody radiation peak at around 300K coincides with the "atmospheric window" 8-13μm. At the same time, the temperature of the earth's surface is also around 300K, so the heat of the object can be released into the huge cold source (3K) in outer space in the form of electromagnetic waves through the atmospheric window. Materials that meet the performance of passive radiation cooling need to have a high reflectivity in the sunlight band and a high mid-infrared emissivity in the "atmospheric window" band.

[0003] With the continuous progress of scientific and technological research, a variety of radiation cooling materials have been proposed, such as multilayer photonic structures, backing high-reflective metal substrates, natural polymer structural materials, etc. However, these materials have disadvantages such as high preparation cost, complex preparation process, and small application scenarios. Therefore, the development of radiation cooling materials with stronger adaptability has important scientific and application value.

[0004] In this structural coating system, PMMA is used as the base material and nano-TiO2 is used as a highly reflective filler, which is mainly used to efficiently reflect visible light and near-infrared light, thereby ensuring that the system has a high reflectivity in the 0.4-2.5μm band range. However, nano-TiO2 exhibits high absorptivity in the ultraviolet (UV) band. In order to solve this problem, high-bandgap BaSO4 particles are added to improve the reflectivity of the coating system in the UV band. This improvement makes up for the defect of high absorption of TiO2 in the UV band, allowing the entire coating system to have a high reflectivity in the sunlight band. In addition, the BaSO4 chemical bond provides additional infrared absorption, which further improves the infrared emissivity of the coating in the atmospheric window. Summary of the invention

[0005] The object of the present invention is to provide an organic composite structure coating that can realize passive radiation cooling, so as to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: an organic composite structural coating capable of realizing passive radiation cooling, wherein the specific preparation steps of the organic composite structural coating capable of realizing passive radiation cooling are as follows:

[0007] Step 1: Weigh 6-10g PMMA, 8-12g BaSO4, and 1-3g TiO2 in a 50ml beaker, and stir them continuously for 30-60s using a stirring rod until they are evenly mixed to obtain a solid mixture;

[0008] Step 2: Add 30-36 ml of DMF to the solid mixture, stir in a water bath at 40-50°C for 4 hours until PMMA is completely dissolved and the system becomes viscous, thereby obtaining a passive radiation cooling coating precursor;

[0009] Step 3: Apply the coating evenly on the substrate with a coating thickness of 0.8-1mm. Place it in a fume hood for one hour to ensure that the airflow in the fume hood is filtered and there is no large amount of dust in the airflow. The coating is initially dried on the substrate. Then, the coating and the substrate are immersed in deionized water for phase transformation to obtain a composite material of the coating and the substrate. The composite material is then taken out of the deionized water, initially drained, and then placed in a fume hood to dry for several hours. The drying temperature is raised to 30-35°C to obtain a passive radiation cooling composite coating.

[0010] Preferably, the substrate is various paper, ceramic, glass, or metal materials.

[0011] Preferably, the temperature in the fume hood needs to be controlled at 25°C.

[0012] Preferably, in step three, the coating and the substrate are immersed in deionized water for a coagulation bath, and the coagulation bath time is controlled within 2-3 hours.

[0013] Preferably, in step three, the composite material is taken out from the deionized water and placed in a fume hood for drying for 3-4 hours.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The preparation process of this application is simple and efficient, the conditions are mild, and it can be prepared on a large scale; the PMMA / BaSO4 / TiO2 structural coating prepared has a good passive radiation cooling effect. 2It can achieve a sub-ambient passive radiation cooling effect of 5°C, and a sub-ambient passive radiation cooling effect of 6°C in hot summer. This material has broad application prospects in the fields of energy conservation, emission reduction and green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Surface scanning electron microscopy of the prepared PMMA / BaSO4 / TiO2 structural coating Figure 1 ;

[0017] Figure 2 Surface scanning electron microscopy of the prepared PMMA / BaSO4 / TiO2 structural coating Figure 2 ;

[0018] Figure 3 This is the 24h passive radiation cooling performance test diagram of the prepared PMMA / BaSO4 / TiO2 structural coating;

[0019] Figure 4 The characteristic diagram of the solar band reflectivity and atmospheric window infrared emissivity of the prepared PMMA / BaSO4 / TiO2 structural coating;

[0020] Figure 5 Schematic diagram of the radiation cooling performance test device. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0022] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] See also Figure 1-5 , the present invention provides a technical solution:

[0024] An organic composite structural coating capable of realizing passive radiative cooling, the specific preparation steps of the organic composite structural coating capable of realizing passive radiative cooling are as follows:

[0025] Step 1: Weigh 6-10g PMMA, 8-12g BaSO4, and 1-3g TiO2 in a 50ml beaker, and stir them continuously for 30-60s using a stirring rod until they are evenly mixed to obtain a solid mixture;

[0026] Step 2: Add 30-36ml DMF to the solid mixture, stir in a 40-50℃ water bath for 4h until PMMA is completely dissolved and the system becomes viscous, thus obtaining a passive radiation cooling coating precursor. DMF (N,N-dimethylformamide) is an organic compound with the chemical formula C3H7NO, and is a colorless, transparent liquid. As a widely used chemical raw material, DMF is also an excellent solvent that can be mixed with water and most organic solvents, and has good solubility for a variety of organic and inorganic compounds.

[0027] Step 3: Apply the coating evenly on the substrate with a coating thickness of 0.8-1mm. Place it in a fume hood for one hour to ensure that the airflow in the fume hood is filtered and that there is no large amount of dust in the airflow to prevent a large amount of dust from adhering to the surface of the coating and affecting the performance of the coating. Initially dry the coating on the substrate, then immerse the coating and the substrate in deionized water for phase transformation to obtain a composite material of the coating and the substrate. Then take the composite material out of the deionized water, drain it initially, and then place it in a fume hood to dry for several hours. The drying temperature is raised to 30-35°C to obtain a passive radiation cooling composite coating.

[0028] Choose a well-ventilated working environment with a suitable temperature for operation. Use appropriate solvents (selected according to the type of substrate) to thoroughly clean the surface of the substrate to remove oil, dust and other impurities. For some materials, slight grinding may be required to improve adhesion. Make sure that the substrate is completely dry before proceeding to the next step. Estimate the total amount of paint required based on the area to be coated, and use a scraper or other suitable tools to evenly apply the paint to the substrate. Pay attention to controlling the thickness to avoid missing or over-thickness. According to the product instructions, it may be necessary to apply thin layers several times to achieve the best effect. Allow enough drying time between each coat. After the last coat is applied, let the paint dry naturally or use other methods to accelerate its drying.

[0029] The substrate is various paper, ceramic, glass, and metal materials.

[0030] The temperature in the fume hood needs to be controlled at 25°C.

[0031] In step 3, the coating and the substrate are immersed in deionized water for a coagulation bath, and the coagulation bath time is controlled to be 2-3 hours. The solvent in the solution is exchanged with the solvent in the coagulation bath, resulting in a change in the solubility of the solution, usually a decrease in solubility, thereby promoting the precipitation of the substance. For example, if a polymer solution is moved from a solvent into a coagulation bath that does not dissolve the polymer, the polymer will precipitate or coagulate.

[0032] In the coagulation bath, in addition to the effect of solvent exchange, a self-assembly process may occur in the solution, especially in polymer solutions or sol-gel systems. This self-assembly process may be triggered by intermolecular interactions or selective solubility of the solvent. The interaction between different molecules in the solvent will lead to phase separation, thus forming a porous structure. As the phase separation process proceeds, the solid phase and the liquid phase are unevenly distributed, and the solid phase forms a network structure with pores in the solution.

[0033] In the step 3, the composite material is taken out from the deionized water and placed in a fume hood for drying for 3-4 hours.

[0034] Embodiment 1:

[0035] The specific preparation steps of the organic composite structure coating that can realize passive radiation cooling are as follows:

[0036] Step 1: Weigh 6 g PMMA, 8 g BaSO4, and 1 g TiO2 in a 50 ml beaker and stir them continuously for 30 seconds using a stirring rod until they are evenly mixed to obtain a solid mixture;

[0037] Step 2: Add 30 ml of DMF to the solid mixture, stir in a 40°C water bath for 4 hours until PMMA is completely dissolved and the system becomes viscous, thereby obtaining a passive radiation cooling coating precursor;

[0038] Step 3: Apply the coating evenly on the substrate with a coating thickness of 0.8 mm, place it in a fume hood for one hour, ensure that the airflow in the fume hood is filtered and there is no large amount of dust in the airflow, preliminarily dry the coating on the substrate, and then immerse the coating and the substrate in deionized water for phase conversion to obtain a composite material of the coating and the substrate, then take the composite material out of the deionized water, preliminarily drain the water, and then place it in a fume hood to dry for several hours, and the drying temperature is increased to 30°C to obtain a passive radiation cooling composite coating;

[0039] Embodiment 2:

[0040] The specific preparation steps of the organic composite structure coating that can realize passive radiation cooling are as follows:

[0041] Step 1: Weigh 8 g PMMA, 10 g BaSO4, and 2 g TiO2 in a 50 ml beaker and stir them continuously for 45 seconds using a stirring rod until they are evenly mixed to obtain a solid mixture;

[0042] Step 2: Add 33 ml of DMF to the solid mixture, stir in a 45°C water bath for 4 hours until PMMA is completely dissolved and the system becomes viscous, thereby obtaining a passive radiation cooling coating precursor;

[0043] Step 3: Apply the coating evenly on the substrate with a coating thickness of 0.9 mm, place it in a fume hood for one hour, ensure that the airflow in the fume hood is filtered and there is no large amount of dust in the airflow, preliminarily dry the coating on the substrate, and then immerse the coating and the substrate in deionized water for phase conversion to obtain a composite material of the coating and the substrate, then take the composite material out of the deionized water, preliminarily drain the water, and then place it in a fume hood to dry for several hours, and the drying temperature is raised to 33°C to obtain a passive radiation cooling composite coating;

[0044] Embodiment 3:

[0045] The specific preparation steps of the organic composite structure coating that can realize passive radiation cooling are as follows:

[0046] Step 1: Weigh 10 g PMMA, 12 g BaSO4, and 3 g TiO2 in a 50 ml beaker and stir them continuously for 60 seconds using a stirring rod until they are evenly mixed to obtain a solid mixture;

[0047] Step 2: Add 36 ml of DMF to the solid mixture, stir in a 50°C water bath for 4 hours until PMMA is completely dissolved and the system becomes viscous, thereby obtaining a passive radiation cooling coating precursor;

[0048] Step 3: Apply the coating evenly on the substrate with a thickness of 1 mm. Place it in a fume hood for one hour to ensure that the airflow in the fume hood is filtered and there is no large amount of dust in the airflow. Initially dry the coating on the substrate, then immerse the coating and the substrate in deionized water for phase transformation to obtain a composite material of the coating and the substrate. Then take the composite material out of the deionized water, drain it initially, and then place it in a fume hood to dry for several hours. The drying temperature is raised to 35°C to obtain a passive radiation cooling composite coating.

[0049] Comparative Example:

[0050] Using the PMMA and solvent preparation parameters in Example 3, a pure PMMA coating (without filler) was set as a control group. The preparation method of this control group is similar to that of Example 3 of this patent, the only difference being that no filler is added to ensure that its performance is determined only by the PMMA matrix.

[0051] Test results and analysis of organic composite structural coatings for passive radiative cooling

[0052] (1) Scanning electron microscopy analysis

[0053] like Figure 1 , 2 As shown, the morphology of the coating surface in Example 3 was observed by scanning electron microscopy, and the surface showed a randomly distributed porous and particle nested structure. The main manifestations are: the micro / nano particles of BaSO4 and TiO2 exist in the larger micropores, and the nanopores are randomly distributed around the micropores and particles. This unique multi-level micro / nanopore and multi-scale combination of particles is conducive to the organic composite structure coating to achieve scattering and reflection of sunlight.

[0054] (2) UV-visible-near infrared reflectivity test

[0055] The reflectivity of the coating was measured using an integrating sphere UV-visible-near infrared spectrophotometer. In Example 1, the reflectivity of the organic composite structure coating was 93.4%. In Examples 2 and 3, the reflectivity was increased due to the adjustment of the ratio, and the highest reached 96.3% (as shown in Table 1 and Table 2). Figure 3 This change shows that by optimizing the ratio of the coating, the ability to reflect sunlight can be effectively improved, thereby reducing the material's absorption of solar radiation and improving the material's radiative cooling performance.

[0056] (3) Mid-infrared emissivity test

[0057] The infrared reflectivity (ρ) and transmittance (τ) of Examples 1, 2, and 3 and the comparative example were measured using a Fourier transform infrared spectrometer with an integrating sphere. The infrared emissivity (ε) was calculated by ε=1-ρ-τ, and the average mid-infrared emissivity was weighted averaged by ε(λ) of the corresponding wavelength and the atmospheric transmittance (the results are shown in Table 1).

[0058] (4) Radiant cooling performance test

[0059] The outdoor radiant cooling performance test was carried out using a self-designed aluminum foil-polystyrene (PS) foam-polyethylene (PE) transparent film device (such as Figure 4As shown). The size of the PS foam is 10cm×10cm×10cm. The function of the PS foam is to reduce the interference of the external environment on the heat conduction of the sample. A 4cm×4cm×2cm groove is opened on the top of the PS foam to test the space temperature below the radiation cooling sample. The outer surface is completely wrapped with 1mm thick aluminum foil to reduce the heat interference of the outside world on the sample. In addition, a layer of transparent PE film is sealed on the top of the sample to reduce the influence of the external environment on the thermal convection of the sample itself. The K-type thermocouple under the sample monitors the temperature on the back of the sample in real time (with an accuracy of 0.1°C). The natural irradiance of the sun is measured using an irradiance tester, and the real-time wind speed and humidity are tested using a digital anemometer. The radiation cooling effect shows obvious differences in different seasons. By comparison, it can be found that in summer, due to the high ambient temperature, the difference in the radiation cooling effect is more obvious. The cooling effect of Example 3 can achieve a 6°C sub-environmental passive radiation cooling effect in the hot summer (such as Figure 5 As shown in Table 1, the radiation cooling performance of the material has a strong response to seasonal changes in a high temperature environment.

[0060] Table 1 Test results of organic composite structural coatings

[0061]

[0062] The organic composite structural coating proposed in this patent that can achieve passive radiative cooling shows excellent radiative cooling performance, providing a new low-carbon and sustainable cooling solution for buildings and other facilities. Compared with traditional active cooling technology, this coating significantly reduces the ambient temperature by enhancing the radiative cooling effect without the need for external energy input, thereby effectively reducing dependence on air conditioning and refrigeration equipment. This innovative technology can not only reduce the energy consumption and operating costs of buildings, but also has significant potential for reducing greenhouse gas emissions, providing strong support for addressing global climate change and achieving carbon neutrality goals. From a life cycle perspective, buildings or facilities using this organic composite coating will significantly reduce energy consumption and carbon dioxide emissions during the cooling process. The high durability and long-term stability of the coating ensure that it continues to work during its service life, thereby further reducing the carbon footprint caused by traditional energy consumption. In addition, this passive radiative cooling technology is particularly suitable for high temperature climate areas, and can effectively cope with the problem of surging energy consumption due to climate warming, becoming an ideal technical choice for solving the heat island effect and energy conservation and emission reduction challenges.

[0063] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

[0064] 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.

Claims

1. An organic composite structural coating capable of realizing passive radiation cooling, characterized in that: The specific preparation steps of the organic composite structure coating that can realize passive radiation cooling are as follows: Step 1: Weigh 6-10g PMMA, 8-12g BaSO4, and 1-3g TiO2 in a 50ml beaker, and stir them continuously for 30-60s using a stirring rod until they are evenly mixed to obtain a solid mixture; Step 2: Add 30-36 ml of DMF to the solid mixture, stir in a water bath at 40-50°C for 4 hours until PMMA is completely dissolved and the system becomes viscous, thereby obtaining a passive radiation cooling coating precursor; Step 3: Apply the coating evenly on the substrate with a coating thickness of 0.8-1mm. Place it in a fume hood for one hour to ensure that the airflow in the fume hood is filtered and there is no large amount of dust in the airflow. The coating is initially dried on the substrate. Then, the coating and the substrate are immersed in deionized water for phase transformation to obtain a composite material of the coating and the substrate. The composite material is then taken out of the deionized water, initially drained, and then placed in a fume hood to dry for several hours. The drying temperature is raised to 30-35°C to obtain a passive radiation cooling composite coating.

2. The organic composite structural coating capable of realizing passive radiation cooling according to claim 1, characterized in that: The substrate is various paper, ceramic, glass, and metal materials.

3. The organic composite structural coating capable of realizing passive radiation cooling according to claim 1, characterized in that: The temperature in the fume hood needs to be controlled at 25°C.

4. The organic composite structural coating capable of realizing passive radiation cooling according to claim 1, characterized in that: In the step three, the coating and the substrate are immersed in deionized water for a coagulation bath, and the coagulation bath time is controlled within 2-3 hours.

5. The organic composite structural coating capable of realizing passive radiation cooling according to claim 1, characterized in that: In the step 3, the composite material is taken out from the deionized water and placed in a fume hood for drying for 3-4 hours.

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