Radiation cooling coating and preparation method thereof

Abstract

The invention discloses a radiation cooling coating and a preparation method thereof. The radiation cooling coating comprises a water-based emulsion, a reflective inorganic filler, a radiation inorganic filler, a heat-conducting inorganic filler, functional nanocellulose and a functional aid, the method comprises the following steps: sieving the reflective inorganic filler, the radiation inorganic filler and the heat-conducting inorganic filler to obtain particles with larger sizes, and mixing the sieved inorganic fillers for later use; adding the functional nano cellulose into the water-based emulsion, and uniformly stirring; adding a functional additive into the water-based emulsion containing the functional nanocellulose, and uniformly stirring; adding the inorganic filler into the water-based emulsion containing the functional nanocellulose and the functional additive in three batches, and uniformly stirring; and storing the prepared coating in a shade place, and regularly stirring during the storage period. The surface temperature of a building can be obviously reduced, and air conditioner energy consumption is reduced; the service life of the coating is prolonged and the maintenance cost is reduced; energy consumption is reduced, carbon emission is reduced, and the development trend of green buildings is met.

Description

Technical Field

[0001] The invention relates to the field of radiation cooling coatings, and in particular to a radiation cooling coating and a preparation method thereof. Background Art

[0002] Faced with the severe challenges of global warming and tight energy supply, the development of new energy-saving and carbon-reducing technologies has become a key way to alleviate these problems. As an innovative zero-energy, zero-pollution refrigeration solution, radiative cooling technology works by efficiently reflecting or scattering the energy of sunlight (wavelength range 0.3 to 2.5 microns) and using the "atmospheric window" (wavelength 8 to 13 microns) to exchange energy with the cosmic background radiation (about 3K temperature), thereby achieving a cooling effect below ambient temperature. Radiative cooling coatings, due to their easy preparation and ready-to-use, have shown great application potential in many fields such as building cooling, reducing evaporation losses in large oil depots, and grain storage.

[0003] However, the mainstream radiation cooling coatings on the market currently mostly use oily solvents. Although this type of coating exhibits excellent coating performance, it will pollute the environment during its production and use, and may pose a threat to human health. In contrast, radiation cooling coatings using water-based solvents have improved in terms of environmental protection and health safety, but their storage stability and comprehensive performance are often inferior to oil-based coatings, and it is difficult to meet high performance requirements. In addition, existing radiation cooling coatings generally face the problem of poor thermal conductivity, and it is difficult to effectively and quickly export internal heat sources, which limits their efficiency in practical applications. Therefore, the development of a new type of radiation cooling coating that uses an environmentally friendly water-based solvent, has long-term storage stability and high thermal conductivity is of great significance for coping with the challenges of global warming and tight energy supply and achieving efficient refrigeration. The present invention aims to provide a method for preparing a radiation cooling coating with a long storage period and high thermal conductivity, which overcomes the shortcomings of the prior art by optimizing the selection of raw materials and the preparation process, and meets the market demand for high-performance, environmentally friendly radiation cooling coatings.

[0004] In the preparation of this coating, high thermal conductivity ceramic powders such as boron nitride and silicon carbide are selected as fillers. These materials have special crystal structures, strong internal atomic bonding, large phonon mean free path, and can efficiently transfer heat. Taking boron nitride as an example, it has a layered structure similar to graphite. The layers are bonded by weak van der Waals forces, and the atoms in the layers are connected by covalent bonds, so that the propagation speed of phonons in the layers is fast, thus having good heat conduction ability. Substances with specific infrared emission characteristics are added to the coating, such as certain metal oxides (titanium dioxide, zinc oxide, etc.). These materials have high emissivity in the infrared band (8-13μm), which corresponds to the "transparent window" of the earth's atmosphere. When the surface of the coating absorbs heat, the molecular vibration energy level increases, and the excited molecules release energy by emitting infrared photons to the outside world. Due to the high emissivity of the selected material in the "transparent window" band, the coating can efficiently emit heat to the cold outer space in the form of infrared radiation, thereby achieving a cooling effect. The microstructure and thickness of the coating can be controlled by adjusting the formulation and preparation process of the coating. Suitable microstructures can increase the emission area of ​​infrared radiation and improve radiation efficiency. Summary of the invention

[0005] In view of this, the present invention provides a radiation cooling coating and a preparation method thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A radiation cooling paint comprises the following components:

[0008] Aqueous emulsion, reflective inorganic filler, radiative inorganic filler, thermally conductive inorganic filler, functional nanocellulose and functional additives.

[0009] Preferably, the aqueous emulsion is one or a mixture of several of aqueous acrylic emulsion, aqueous epoxy resin emulsion, aqueous fluorocarbon emulsion and aqueous silicone emulsion.

[0010] Preferably, the reflective inorganic filler is one or a mixture of nano calcium carbonate, nano titanium dioxide, nano silicon dioxide, nano barium sulfate, and nano attapulgite.

[0011] Preferably, the radiation-type inorganic filler is one or a mixture of nano-calcium carbonate, nano-aluminum oxide, nano-silicon dioxide, and nano-silicon nitride.

[0012] Preferably, the thermally conductive inorganic filler is one or a mixture of nano-boron nitride, nano-diamond, and nano-alumina.

[0013] Preferably, the functional nanocellulose is TEMPO nanocellulose, fluorinated nanocellulose or a mixture of the two or more thereof.

[0014] Preferably, the functional additive is a dispersant, a leveling agent, a film-forming agent, or a thickener.

[0015] Preferably, the solid content of the aqueous emulsion is 20 to 30 wt %.

[0016] A method for preparing a radiation cooling coating comprises the following steps:

[0017] Step 1: Screen the reflective inorganic filler, the radiant inorganic filler, and the thermal conductive inorganic filler to select larger particles, and mix the screened inorganic fillers for later use;

[0018] Step 2: adding functional nanocellulose into the aqueous emulsion and stirring evenly;

[0019] Step 3: adding the functional additive into the aqueous emulsion containing the functional nanocellulose and stirring evenly;

[0020] Step 4: adding the inorganic filler into the aqueous emulsion containing the functional nanocellulose and the functional additive in three batches and stirring evenly;

[0021] Step 5: Store the coating prepared above in a cool place and stir it regularly during storage.

[0022] Preferably, in the step 1, sieving is performed using a 300-mesh sieve.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] (1) The present invention has a highly efficient cooling effect: through selective reflection technology, the surface temperature of the building is significantly reduced, reducing air conditioning energy consumption;

[0025] (2) The present invention has self-cleaning properties: the super-hydrophobic surface effectively prevents dirt from adhering, prolongs the service life of the coating, and reduces maintenance costs;

[0026] (3) The present invention is environmentally friendly and energy-saving: it reduces energy consumption, lowers carbon emissions, and complies with the development trend of green buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] none DETAILED DESCRIPTION

[0028] The following will be combined with 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 making creative work are within the scope of protection of the present invention.

[0029] The invention discloses a radiation cooling coating, comprising the following components:

[0030] Aqueous emulsion, reflective inorganic filler, radiative inorganic filler, thermally conductive inorganic filler, functional nanocellulose and functional additives.

[0031] Wherein, the aqueous emulsion is one or a mixture of aqueous acrylic emulsion, aqueous epoxy resin emulsion, aqueous fluorocarbon emulsion, aqueous silicone emulsion;

[0032] The reflective inorganic filler is one or a mixture of nano calcium carbonate, nano titanium dioxide, nano silicon dioxide, nano barium sulfate, and nano attapulgite;

[0033] The radiation-type inorganic filler is one or a mixture of nano calcium carbonate, nano alumina, nano silicon dioxide, and nano silicon nitride;

[0034] The thermally conductive inorganic filler is one or a mixture of nano boron nitride, nano diamond, and nano alumina;

[0035] The functional nanocellulose is one or a mixture of TEMPO nanocellulose and fluorinated nanocellulose;

[0036] Functional additives include dispersants, leveling agents, film formers, and thickeners;

[0037] The solid content of the aqueous emulsion is 20 to 30 wt%;

[0038] The present invention also discloses a method for preparing a radiation cooling coating, comprising the following steps:

[0039] Step 1: Screen the reflective inorganic filler, the radiant inorganic filler, and the thermal conductive inorganic filler using a 300-mesh screen to screen out larger particles, and mix the screened inorganic fillers for later use;

[0040] Step 2: adding functional nanocellulose into the aqueous emulsion and stirring evenly;

[0041] Step 3: adding the functional additive into the aqueous emulsion containing the functional nanocellulose and stirring evenly;

[0042] Step 4: adding the inorganic filler into the aqueous emulsion containing the functional nanocellulose and the functional additive in three batches and stirring evenly;

[0043] Step 5: Store the coating prepared above in a cool place and stir it regularly during storage.

[0044] Example 1

[0045] A radiation cooling paint comprises the following components:

[0046] 100kg water-based epoxy resin emulsion, 40kg nano calcium carbonate, 25kg nano silicon dioxide, 15kg nano boron nitride, 0.1kg TEMPO cellulose and 5kg functional additives.

[0047] Stirring temperature: 20°C, stirring time: 0.5h, rotation speed: 800 rpm.

[0048] Example 2

[0049] 100kg water-based acrylic emulsion, 45kg nano-barium sulfate, 22kg nano-silicon nitride, 18kg nano-diamond, 0.2kg fluorinated nano-cellulose and 8kg functional additives.

[0050] Stirring temperature: 25°C, stirring time: 1h, rotation speed: 900 rpm.

[0051] Example 3

[0052] 50kg water-based acrylic emulsion, 50kg water-based silicone emulsion, 50kg nano-attapulgite, 25kg nano-calcium carbonate, 20kg nano-alumina, 0.2kg fluorinated nano-cellulose and 10kg functional additives.

[0053] Stirring temperature: 26°C, stirring time: 1h, rotation speed: 1000 rpm.

[0054] Example 4

[0055] 100kg water-based fluorocarbon emulsion, 20kg nano titanium dioxide, 40kg nano calcium carbonate, 10kg nano silicon nitride, 15kg nano boron nitride, 0.1kg TEMPO nano cellulose and 6kg functional additives.

[0056] Stirring temperature: 30°C, stirring time: 0.5h, rotation speed: 1200 rpm.

[0057] Example 5

[0058] 100kg water-based acrylic emulsion, 15kg nano titanium dioxide, 23kg nano calcium carbonate, 15kg nano barium sulfate, 8kg nano aluminum oxide, 8kg nano silicon nitride, 10kg nano boron nitride, 10kg nano diamond, 0.1kg TEMPO nano cellulose, 0.1kg fluorinated nano cellulose and 10kg functional additives.

[0059] Stirring temperature: 25°C, stirring time: 1h, rotation speed: 1200 rpm.

[0060] The results of the embodiment are as follows:

[0061]

[0062] Results comparison

[0063] 1. Comparison of material properties

[0064] (1) Physical properties of reflective inorganic fillers

[0065] Different reflective inorganic fillers, such as nano-calcium carbonate, nano-titanium dioxide, nano-silicon dioxide, nano-barium sulfate and nano-attapulgite, have different crystal structures, refractive indices, densities and surface morphologies.

[0066] These differences in physical properties result in different reflection, scattering and absorption characteristics of light.

[0067] Among them, nano calcium carbonate has high whiteness and glossiness, and can better reflect visible light and part of infrared light;

[0068] Nano-titanium dioxide has excellent ultraviolet light shielding properties and a high refractive index, and can reflect light in a wider spectrum range;

[0069] Nano-silica helps improve the transparency and gloss of coatings, but its reflective properties may be slightly inferior to other fillers;

[0070] Nano-barium sulfate has high density and excellent radiation absorption ability. It is often used to improve the density and radiation protection performance of coatings. It can also reflect a certain amount of light.

[0071] Nano-attapulgite has a unique rod-like structure that can form a micro-nano structure, enhance the light scattering effect, and thus improve the reflectivity of the coating.

[0072] (2) Relationship between reflection intensity and composition

[0073] The reflection intensity of reflective inorganic fillers is closely related to their ability to reflect and scatter light.

[0074] Different fillers have different reflection and scattering effects on light due to differences in physical properties. For example, nano-titanium dioxide usually has a higher reflection intensity due to its high refractive index and excellent UV light shielding performance. Although nano-calcium carbonate can also reflect light, its reflection intensity may vary due to factors such as crystal structure and particle size distribution.

[0075] 2. Stability comparison

[0076] While stability is not the primary factor determining changes in reflectivity, it does affect the long-term performance of the coating.

[0077] Fillers with poor stability may cause delamination and precipitation of the coating during use, thus affecting its reflective performance. Therefore, when selecting reflective inorganic fillers, in addition to considering its reflective performance, it is also necessary to pay attention to its stability.

[0078] Among them, nano-titanium dioxide usually has good chemical stability and weather resistance, and can maintain stable reflective performance under a variety of environmental conditions;

[0079] Nanosilica also has high stability, but it may vary depending on the surface properties;

[0080] Nano calcium carbonate has moderate stability, but its dispersibility and stability may be affected by factors such as particle size and shape;

[0081] Nano-barium sulfate has high density and good stability, but its reflective properties may be affected by factors such as particle size and shape;

[0082] The stability of nano-attapulgite may vary due to different preparation processes and surface treatments, but it usually has good dispersibility and film-forming properties;

[0083] The high infrared emissivity of nano-alumina is related to the crystal form, particle size, and impurities. The thermal stability depends on the crystal form, purity, and preparation process. The chemical stability is affected by the crystal form, purity, and surface condition. The scattering ability is related to the particle shape, size distribution, and pigment synergy. The dispersibility is related to the surface characteristics, dispersant, and preparation pretreatment.

[0084] Nano silicon nitride has small particle size, large specific surface area, high surface activity, and its optical properties are affected by particle size, etc. It has excellent chemical stability and strong wear resistance.

[0085] Nano boron nitride has high hardness and wear resistance, which are affected by the degree of crystallization and particle size; high thermal conductivity, which is related to the crystal structure and purity; high chemical stability, which is affected by the crystal structure and surface state;

[0086] Nanodiamond has high hardness and wear resistance, which are affected by crystal structure and defects; excellent thermal conductivity, which is related to crystal quality; and good chemical stability.

[0087] Note: The above stability ranking is based on general experience only and is not absolute. In actual applications, the stability of fillers may be affected by many factors, such as temperature, humidity, light, pH value, etc. Therefore, when selecting reflective inorganic fillers, it is necessary to make comprehensive considerations based on the specific application environment and requirements.

[0088] The present invention adjusts the formula and preparation process of the coating, and through experimental research conducted in the field of construction, it is found that applying the cooling coating on the exterior walls and roofs of buildings can significantly exert its effective reflection effect on infrared and visible light in sunlight, thereby greatly reducing the heat absorption of the building.

[0089] In the high temperature environment in summer, the indoor temperature of buildings without cooling paint can generally reach more than 30℃, while the indoor temperature of buildings with cooling paint obtained in the experiment can be reduced by about 3-8℃ on average. The cooling paint has excellent optical properties. After professional testing and experimental verification, its reflectivity is as high as more than 90%. This ultra-high reflectivity means that the cooling paint can effectively reflect infrared and visible light in sunlight, thereby greatly reducing heat absorption.

[0090] This experimental result strongly proves that the application of cooling coatings in the construction field has a significant effect on reducing indoor temperature and improving indoor thermal environment, providing a practical technical approach and practical basis for building energy conservation and improving living comfort.

[0091] Experimental studies on vehicles such as automobiles have shown that spraying cooling paint on the surface of the vehicle body can effectively reduce the temperature of the vehicle body. Under direct sunlight, experimental data show that the temperature of an ordinary car body can rise to 60-70°C without cooling paint. However, when cooling paint is used, the temperature of the car body can be reduced by 10-20°C. This significant cooling effect effectively reduces the accumulation of heat in the car, thereby greatly reducing the load of the air conditioning system. It can be seen that the present invention has a significant cooling effect.

[0092] It is speculated that the application of refrigeration coatings can significantly reduce air conditioning energy consumption. After using refrigeration coatings, the air conditioning system does not need to be in high-load operation for a long time as before, and its energy consumption can be reduced by about 15%-30%. Through a series of targeted experimental studies, it was found that the use of refrigeration coatings can effectively reduce the surface temperature of equipment.

[0093] During the experiment, it was observed that the reduction in the surface temperature of the equipment greatly reduced the aging and damage of equipment components caused by high temperature factors. After long-term tracking and data analysis, it was finally concluded that the application of refrigeration coatings can significantly extend the service life of equipment, provide reliable guarantees for the stable operation and long-term use of equipment, and have important economic benefits and practical value.

[0094] As an innovative material, the coating of the present invention has broad application prospects. The following are its main application scenarios:

[0095] Construction

[0096] 1. Exterior wall: Cooling coatings can be applied to the exterior walls of buildings, especially in areas with strong direct sunlight and high temperatures. This helps reduce the solar radiation heat entering the room, reduces indoor temperature fluctuations, and reduces air conditioning energy consumption.

[0097] 2. Roof: The roof is the part of the building that is most directly exposed to solar radiation. A roof coated with cooling paint can effectively reflect sunlight and reduce heat absorption, thereby lowering indoor temperature and improving the energy efficiency of the building.

[0098] Refrigeration equipment

[0099] 1. Air conditioning heat exchanger: Refrigeration coatings can be used in the condenser and evaporator of the air conditioner to improve the heat conduction efficiency, accelerate the heat exchange, and thus improve the operating efficiency of the air conditioner.

[0100] 2. Refrigerators and freezers: Applying refrigeration paint on the inner and outer walls of refrigerators and freezers can enhance the insulation effect, reduce energy consumption, reduce internal ice formation, and extend the service life of the equipment.

[0101] Automotive

[0102] 1. Car body surface: Cooling coatings can be applied to the car body surface, especially the roof and hood, which are easily exposed to direct sunlight. This helps to reduce the temperature inside the car and improve driving and riding comfort.

[0103] 2. Car windows: Although car windows are not the main application area for cooling coatings, some transparent cooling coating technologies (if mature) can also be used on car windows to reduce solar radiation entering the car.

[0104] Power communication field

[0105] 1. Power communication cabinet: Refrigeration coatings can be used on the outer walls and internal key equipment surfaces of power communication cabinets to reduce the temperature inside the cabinet and ensure the normal operation of the equipment.

[0106] 2. Transformers and cables: For certain transformers and cables exposed to the outside, cooling coatings can also help reduce their surface temperature and extend their service life.

[0107] Clothing field

[0108] 1. Outdoor clothing: Cooling coatings can be applied to the fabrics of outdoor clothing, especially those worn in summer or in high temperature environments. This helps to reduce the surface temperature of the clothing and improve the comfort of the wearer.

[0109] 2. Sportswear: For sportswear that requires long-term outdoor activities, the application of cooling coatings can also provide a cool and comfortable feeling, reduce sweat accumulation, and improve sports performance.

[0110] 3. Summer clothing: Summer clothing is one of the main application areas of refrigeration coatings, which can bring a cooler wearing experience to the wearer by lowering the temperature of clothing.

[0111] In summary, the refrigeration coating has important application value in many fields due to its unique refrigeration effect and wide applicability. The application field of the present invention is not limited to the fields listed above, and the application of the present invention in other fields also belongs to the protection scope of the present invention. With the continuous advancement of technology and the improvement of coating performance, its application field will be further expanded.

[0112] In terms of preparation, the coating of the present invention uses high thermal conductivity ceramic powders such as boron nitride and carbide as fillers, adds substances with specific infrared emission characteristics, such as metal oxides, and controls the microstructure and thickness of the coating by optimizing the formula and preparation process to improve radiation efficiency.

[0113] The preparation method comprises the steps of screening inorganic fillers, mixing functional nanocellulose and aqueous emulsion, adding functional additives and the like.

[0114] The experimental results show that the cooling paint has a significant cooling effect in the fields of construction, automobiles, etc., and can effectively reduce heat absorption, lower indoor temperature, and reduce air conditioning energy consumption. For example, in the construction field, the indoor temperature of buildings coated with cooling paint can be reduced by 3-8℃℃, and air conditioning energy consumption can be reduced by 15%-30%. At the same time, the paint also has self-cleaning properties, which can extend the service life of the coating and reduce maintenance costs.

[0115] In addition, the cooling coating has a wide range of application prospects, including building exterior walls, roofs, refrigeration equipment, automobile bodies, power communication cabinets and other fields, which helps to improve energy efficiency, reduce carbon emissions, and conform to the development trend of green buildings. By continuously optimizing coating performance and expanding application areas, radiant cooling coatings are expected to play a greater role in the future.

[0116] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A radiation cooling paint, characterized in that: Includes the following components: Aqueous emulsion, reflective inorganic filler, radiative inorganic filler, thermally conductive inorganic filler, functional nanocellulose and functional additives.

2. The radiant cooling paint according to claim 1, characterized in that: The aqueous emulsion is one or a mixture of several of aqueous acrylic emulsion, aqueous epoxy resin emulsion, aqueous fluorocarbon emulsion and aqueous silicone emulsion.

3. The radiant cooling paint according to claim 1, characterized in that: The reflective inorganic filler is one or a mixture of nano calcium carbonate, nano titanium dioxide, nano silicon dioxide, nano barium sulfate and nano attapulgite.

4. The radiant cooling paint according to claim 1, characterized in that: The radiation-type inorganic filler is one or a mixture of nano calcium carbonate, nano alumina, nano silicon dioxide and nano silicon nitride.

5. The radiant cooling paint according to claim 1, characterized in that: The thermally conductive inorganic filler is one or a mixture of nano boron nitride, nano diamond and nano alumina.

6. The radiant cooling paint according to claim 1, characterized in that: The functional nanocellulose is TEMPO nanocellulose, fluorinated nanocellulose or a mixture of the two or more thereof.

7. The radiant cooling paint according to claim 1, characterized in that: The functional additives are dispersants, leveling agents, film-forming agents and thickeners.

8. The radiant cooling paint according to claim 1, characterized in that: The solid content of the aqueous emulsion is 20-30 wt %.

9. A method for preparing a radiation cooling coating, characterized in that: The following steps are involved: Step 1: Screen the reflective inorganic filler, the radiant inorganic filler, and the thermal conductive inorganic filler to select larger particles, and mix the screened inorganic fillers for later use; Step 2: adding functional nanocellulose into the aqueous emulsion and stirring evenly; Step 3: adding the functional additive into the aqueous emulsion containing the functional nanocellulose and stirring evenly; Step 4: adding the inorganic filler into the aqueous emulsion containing the functional nanocellulose and the functional additive in three batches and stirring evenly; Step 5: Store the coating prepared above in a cool place and stir it regularly during storage.

10. The method for preparing a radiant cooling coating according to claim 9, characterized in that: In the step 1, sieving is performed using a 300-mesh sieve.

Images