A high-efficiency moisture-absorbing and cooling coating, coating and preparation method thereof

Abstract

The present invention discloses a kind of high-efficiency hygroscopic cooling coating and its coating and preparation method, the coating includes water, particle filler and radiation cooling functional resin, the particle filler is distributed in the radiation cooling functional resin, the coating includes 20wt%-60wt% of particle filler and 5wt%-15wt% of water; the water is distributed in the coating in the form of droplets so that the formed paint layer produces a hole structure; the particle filler includes radiation cooling filler and hygroscopic filler, and the coating includes 5wt%-20wt% of hygroscopic filler. The present invention prepares a porous topcoat resin layer based on the hygroscopic cooling coating, combines active evaporative heat dissipation and passive radiative cooling in the porous topcoat resin layer, generates large-aperture holes in the coating by the addition of water, and makes the holes evenly distributed by the control of the rotation speed, and the radiation cooling filler and the hygroscopic filler carry out heat transfer based on the holes, synergistically promoting the improvement of the heat dissipation effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of cooling coatings, and in particular relates to a high-efficiency moisture-absorbing cooling coating, a coating thereof and a preparation method thereof. Background Art

[0002] Every object on Earth, including humans and buildings, continuously radiates heat. This heat is absorbed by Earth's atmosphere and reradiated back to the surface as infrared radiation. However, infrared radiation with wavelengths between 8 and 13 microns can easily penetrate the atmosphere, escaping Earth and escaping into the coldness of space. This phenomenon is known as enhanced natural cooling, or more specifically, passive radiative cooling. Radiative cooling uses outer space as a heat source and objects on Earth as heat sources to establish a radiative heat transfer channel. Through this "atmospheric window," heat is transferred directly from objects on Earth to outer space in the form of electromagnetic radiation in a specific wavelength band, without consuming any energy, thereby achieving cooling.

[0003] Although scientists have been aware of the potential of this phenomenon since the 1960s, passive radiation cooling is limited to nighttime applications in practical applications because the heat provided by the sun during the day is much greater than the heat reflected back into space. Secondly, in extreme weather conditions, existing thermal management technologies, including floor heating, air conditioning, and fans, consume huge amounts of energy, which is not conducive to the realization of the "dual carbon" goals. In this context, spectral regulation technology has attracted widespread attention. By designing the specific spectrum of the material to affect its interaction with light, the energy flow on the surface of the object is changed, thereby achieving efficient thermal management of the surface of the object. However, its theoretical limit is generally 120 W / m 2 , it is difficult to meet the cooling needs in extremely hot environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-efficiency moisture-absorbing and cooling coating, a coating thereof and a preparation method thereof, in order to solve the above-mentioned problems.

[0005] The present invention is mainly achieved through the following technical solutions:

[0006] A high-efficiency hygroscopic and cooling coating comprises water, a particle filler, and a radiation cooling functional resin, wherein the particle filler is distributed in the radiation cooling functional resin, and the coating comprises 20wt%-60wt% of the particle filler and 5wt%-15wt% of water; the water is distributed in the coating in the form of droplets so that a formed paint layer has a porous structure; the particle filler comprises a radiation cooling filler and a hygroscopic filler, and the coating comprises 5wt%-20wt% of the hygroscopic filler.

[0007] In order to better implement the present invention, further, the radiation refrigeration filler includes any one or more of titanium dioxide, barium sulfate, and polytetrafluoroethylene; the particle size of the titanium dioxide is 350-550 nm, the particle size of the barium sulfate is 550-1000 nm, and the particle size of the polytetrafluoroethylene is 1-2.5 μm.

[0008] In order to better realize the present invention, further, the coating includes 10wt%-15wt% of titanium dioxide, 5wt%-10wt% of barium sulfate and 5wt%-10wt% of polytetrafluoroethylene.

[0009] In order to better implement the present invention, further, the refractive index of the barium sulfate is 1.5, and the refractive index of the radiation cooling functional resin is less than 1.

[0010] In order to better implement the present invention, further, the hygroscopic filler includes any one or more of lithium bromide, lithium chloride, magnesium chloride, and calcium chloride.

[0011] In order to better implement the present invention, further, the radiation cooling functional resin includes fluorocarbon resin.

[0012] The present invention is mainly achieved through the following technical solutions:

[0013] A high-efficiency moisture-absorbing and cooling coating comprises a porous topcoat resin layer prepared from the above-mentioned high-efficiency moisture-absorbing and cooling coating.

[0014] In order to better implement the present invention, further, it includes a primer resin layer, in which 30wt%-50wt% of zinc powder and 5wt% of calcium carbonate are distributed, and the particle size of the calcium carbonate is 1000-2500 nm.

[0015] In order to better implement the present invention, further, the thickness of the primer resin layer is 30um, and the thickness of the topcoat resin layer is 120-140um.

[0016] The present invention is mainly achieved through the following technical solutions:

[0017] A method for preparing a high-efficiency moisture-absorbing and cooling coating comprises the following steps:

[0018] Step S1: preparing a moisture-absorbing and cooling coating;

[0019] Step S11: adding solvents with different evaporation rates to the radiation cooling functional resin and stirring evenly;

[0020] Step S12: Then, add the radiation refrigeration filler and the hygroscopic filler and stir evenly;

[0021] Step S13: Finally, 5 wt%-15 wt% water is added, and the stirring speed is 3000-8000 r / min;

[0022] Step S2: preparing a porous topcoat resin layer;

[0023] Step S21: applying a moisture-absorbing and cooling coating, and solvents with different evaporation rates evaporate successively to form a film;

[0024] Step S22: After the topcoat resin layer is solidified, the water evaporates and forms a plurality of holes on the paint surface.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The present invention prepares a porous topcoat resin layer based on a hygroscopic cooling coating, and combines active evaporative heat dissipation with passive radiative cooling in the porous topcoat resin layer. Large-diameter pores are generated in the coating by adding water, and the distribution of the pores is uniform by controlling the rotation speed. The radiative cooling filler and the hygroscopic filler conduct heat transfer based on the pores, synergistically promoting the improvement of the heat dissipation effect. Specifically, at night, due to the radiative cooling effect of the radiative cooling filler and the radiative cooling functional resin, the temperature of the coating surface is lower than the ambient temperature, which helps the hygroscopic particles absorb moisture in the air; during the day, the combined effect of water evaporation and radiative cooling is used to achieve comprehensive cooling, ultimately improving the overall cooling effect. Experiments have confirmed that the coating prepared by the present invention has a solar reflectivity of more than 90wt%, an infrared emissivity of more than 92wt%, and a hygroscopic capacity of more than 50wt%.

[0027] (2) The present invention creates pores by adding solvents with different evaporation rates to the hygroscopic and cooling coating, based on the principle of sequential evaporation of the solvents. After the topcoat resin layer solidifies, the water evaporates, forming irregular, tiny pores on the paint surface. This increases the contact area between the topcoat resin layer and the air, significantly increasing the water absorption rate of the hygroscopic particles and the efficiency of water evaporation and heat dissipation, further enhancing the evaporative heat dissipation performance. Secondly, vigorous stirring is the key to increasing porosity. The optimized rotational speed parameters significantly optimize the distribution and size of the pores on the coating surface, accelerating the establishment of optimal heat conduction channels.

[0028] (3) The present invention uses a topcoat resin layer as the main functional layer for reflecting visible-near infrared bands (sunlight bands), emitting mid- and far-infrared bands, and absorbing moisture. The primer resin layer not only increases the adhesion between the topcoat and the substrate, reduces the surface roughness of the substrate, and improves the overall weather resistance of the topcoat resin layer, but also increases the reflection of the near-infrared band, greatly enhancing the solar reflectivity of the overall paint layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a scanning electron microscope image of the surface of the topcoat resin layer at a size of 500 μm;

[0030] Figure 2 This is a scanning electron microscope image of the surface of the topcoat resin layer at a size of 5 μm;

[0031] Figure 3 This is a scanning electron microscope image of large holes on the surface of the topcoat resin layer;

[0032] Figure 4 Schematic diagram of the test of moisture absorption rate of coatings with different proportions of hygroscopic materials added;

[0033] Figure 5 The infrared emissivity spectra of the paint resin layer after adding different hygroscopic materials;

[0034] Figure 6 This is the solar reflectance spectrum of the paint resin layer after adding different hygroscopic materials. DETAILED DESCRIPTION

[0035] Example

[0036] A high-efficiency hygroscopic and cooling coating comprises water, a particle filler, and a radiation cooling functional resin, wherein the particle filler is distributed in the radiation cooling functional resin, and the coating comprises 20wt%-60wt% of the particle filler and 5wt%-15wt% of water; the water is distributed in the coating in the form of droplets so that a formed paint layer has a porous structure; the particle filler comprises a radiation cooling filler and a hygroscopic filler, and the coating comprises 5wt%-20wt% of the hygroscopic filler.

[0037] Preferably, the radiative cooling filler comprises any one or more of titanium dioxide, barium sulfate, and polytetrafluoroethylene. The hygroscopic filler comprises any one or more of lithium bromide, magnesium chloride, magnesium chloride, and calcium chloride. Preferably, the titanium dioxide has a particle size of 350-550 nm, the barium sulfate has a particle size of 550-1000 nm, and the polytetrafluoroethylene has a particle size of 1-2.5 μm. The barium sulfate has a refractive index of 1.5, and the radiative cooling functional resin has a refractive index of less than 1.

[0038] The present invention uses a porous topcoat resin layer prepared from a hygroscopic cooling coating. This layer combines active evaporative heat dissipation with passive radiative cooling. Large-diameter pores are created in the coating by the addition of water, and the pores are evenly distributed by controlling the rotational speed. The radiative cooling filler and the hygroscopic filler transfer heat through the pores, synergistically promoting improved heat dissipation. Specifically, at night, the radiative cooling filler and the radiative cooling functional resin lower the coating surface temperature below the ambient temperature, helping the hygroscopic particles absorb moisture from the air. During the day, the combined effects of water evaporation and radiative cooling provide a comprehensive cooling effect, ultimately enhancing the overall cooling effect.

[0039] Example

[0040] A high-efficiency moisture-absorbing and cooling coating comprises a topcoat resin layer and a primer resin layer. The topcoat resin layer serves as the primary functional layer, reflecting visible and near-infrared wavelengths (sunlight wavelengths), emitting mid- and far-infrared wavelengths, and absorbing moisture. The primer resin layer not only enhances adhesion between the topcoat and the substrate, reduces substrate surface roughness, and improves the overall weatherability of the topcoat resin layer, but also increases reflection in the near-infrared wavelengths, significantly enhancing the overall solar reflectivity of the paint layer. Preferably, the primer resin layer is 30 μm thick, and the topcoat resin layer is 120-140 μm thick.

[0041] Specifically, the topcoat resin layer is prepared from a high-efficiency hygroscopic and cooling coating, which includes a fluorocarbon varnish and a particle filler. The fluorocarbon varnish has excellent weather resistance and spectral characteristics that are more difficult to change. The particle filler includes a radiant refrigeration filler and a hygroscopic filler. The hygroscopic material is used singly or in combination, and the total mass ratio is 5wt%-20wt%. The hygroscopic filler mainly absorbs and stores moisture. Due to the presence of FC bonds in the fluorocarbon varnish, it has excellent mid- and far-infrared emissivity, can effectively emit mid- and far-infrared to the outside, and further reduce the temperature.

[0042] Preferably, the radiative cooling filler includes titanium dioxide, barium sulfate, and polytetrafluoroethylene; the hygroscopic filler includes lithium bromide, lithium chloride, magnesium chloride, and calcium chloride. The titanium dioxide has a particle size of 350-550 nm, primarily reflecting sunlight and accounting for 10-15 wt% of the total mass. The barium sulfate has a particle size of 550-1000 nm, accounting for 5-10 wt% of the total mass. The polytetrafluoroethylene has a particle size of 1-2.5 μm, accounting for 5-10 wt% of the total mass, reflecting near-infrared radiation. Preferably, the refractive index of the barium sulfate is 1.5, while the refractive index of the fluorocarbon varnish is less than 1. This significant difference in refractive index further increases the overall sunlight reflectivity.

[0043] Preferably, in the preparation process of high-efficiency hygroscopic cooling coating, 10wt% of water is added, and after vigorous stirring, fluorocarbon varnish is immiscible with water, and water forms multiple tiny droplets inside fluorocarbon varnish. After brushing, the solvent in fluorocarbon varnish evaporates first, and after the topcoat resin layer is cured, water evaporates therewith, and irregular tiny holes are formed in the paint surface, which increases the topcoat resin layer and the air contact area, and helps to improve the water absorption and water evaporation of hygroscopic particles such as lithium bromide, and further enhances evaporative heat dissipation efficiency. Specifically, after fluorocarbon varnish is added with diluent and stirred evenly, particulate filler is added and stirred for 6 hours, and then 10wt% of water is added and stirred vigorously for half an hour, and the rotating speed is more than 2000 r / min, and high-efficiency hygroscopic cooling coating can be obtained. Preferably, solvents with different evaporation rates are added to the coating, and pores are made by the principle that the solvent evaporates successively. Secondly, vigorous stirring is the key to improving porosity, and the faster the rotating speed, the smaller the droplets formed, and the preferred rotating speed is 3000-8000 r / min.

[0044] Preferably, the primer resin layer is prepared from a primer coating, which includes an epoxy zinc-rich varnish and 5wt% calcium carbonate, and the particle size of the calcium carbonate is 1000-2500 nm. Epoxy zinc-rich varnish is rich in zinc powder and has a cathodic protection effect on steel substrates, so it is a preferred anti-rust primer. In addition, its paint film has good toughness and is easy to construct. It is currently widely used as an anti-corrosion primer for paint. The addition of calcium carbonate increases the near-infrared reflectivity of the primer, further reflects the near-infrared light transmitted through the topcoat, and increases the overall reflective effect of the coating. Preferably, the content of zinc in the epoxy zinc-rich varnish ranges from 30wt% to 50wt%.

[0045] The advantages of the fluorocarbon varnish are:

[0046] Excellent anti-corrosion performance: thanks to its excellent chemical inertness, the paint film is resistant to acids, alkalis, salts and other chemicals and a variety of chemical solvents, providing a protective barrier for the substrate;

[0047] It has excellent physical and mechanical properties: high surface hardness, impact resistance, anti-buckling and good wear resistance;

[0048] Subsequent maintenance-free: It has self-cleaning capabilities, and surface dust can be self-cleaned by rainwater;

[0049] Strong adhesion: It has excellent adhesion on metal, plastic, cement, composite materials and other surfaces;

[0050] High decorative properties: in a 60-degree gloss meter, it can reach a high gloss of more than 80wt%;

[0051] Ultra-long weather resistance: The coating contains a large number of F--C bonds, does not powder or fade, and has a service life of up to 20 years.

[0052] The epoxy zinc-rich primer is made of epoxy resin and zinc powder as the main raw materials, and also includes thickeners, fillers, additives, solvents, etc. It has the characteristics of fast natural drying, strong adhesion, and strong corrosion resistance. The fluorocarbon varnish and epoxy zinc-rich varnish are both commercially available products, so they will not be described in detail.

[0053] like Figure 1-Figure 3 As shown in FIG, the topcoat resin layer prepared by the present invention has a porous structure, and relatively regular large-sized holes are generated on the surface by water evaporation, and the pore diameter of the holes is 265.7nm-351.8nm. Figure 5 and Figure 6 As shown in the figure, after adding lithium bromide, lithium chloride, magnesium chloride and calcium chloride respectively, the influence of each hygroscopic material on the infrared emissivity and solar reflectivity of the coating is similar. Figure 4 As shown, (a)-(f) are schematic diagrams of moisture absorption test of the topcoat resin layer when the proportion of hygroscopic filler is 0, 1wt%, 5wt%, 10wt%, 15wt% and 20wt%, respectively. The moisture absorption rates of the topcoat resin layer in (a)-(f) are 0, 3.2wt%, 8wt%, 9.8wt%, 27.6wt% and 54wt%, respectively, and the moisture absorption rate of the topcoat resin layer in (f) is the highest.

[0054] The topcoat resin layer of the present invention not only absorbs water, but also acts as a radiation cooling effect. During the day, the temperature is lowered based on the combined effect of water evaporation and radiation cooling. At night, the topcoat resin layer is lower than the surrounding environment due to the radiation cooling effect, which is more conducive to the absorption of moisture by the hygroscopic filler. Secondly, the topcoat resin layer is located on the upper layer of the primer resin layer, and there will be no repeated water absorption and evaporation, frequent changes in volume, and the problems of deformation and falling off of the upper paint body. The topcoat resin layer of the present invention is a porous structure, which can absorb water quickly, and the fluorocarbon varnish has excellent weather resistance and water corrosion resistance, and is more excellent in terms of performance and weather resistance. It has been confirmed by experiments that the solar reflectivity of the coating prepared by the present invention is as high as more than 90wt%, the infrared emissivity is as high as more than 92wt%, and the moisture absorption capacity is as high as more than 50wt%.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-efficiency moisture-absorbing and cooling coating, characterized in that: The invention comprises water, particle fillers and a radiation cooling functional resin, wherein the particle fillers are distributed in the radiation cooling functional resin, and the coating comprises 20wt%-60wt% of the particle fillers and 5wt%-15wt% of water; the water is distributed in the coating in the form of droplets so that the formed paint layer has a porous structure; the particle fillers include radiation cooling fillers and hygroscopic fillers, and the coating comprises 5wt%-20wt% of the hygroscopic fillers; the coating also comprises solvents with different evaporation rates, and the solvent evaporates first, followed by the water.

2. A high-efficiency moisture-absorbing and cooling coating according to claim 1, characterized in that: The radiation refrigeration filler includes any one or more of titanium dioxide, barium sulfate, and polytetrafluoroethylene; the particle size of the titanium dioxide is 350-550 nm, the particle size of the barium sulfate is 550-1000 nm, and the particle size of the polytetrafluoroethylene is 1-2.5 μm.

3. A high-efficiency moisture-absorbing and cooling coating according to claim 2, characterized in that: The coating comprises 10wt%-15wt% of titanium dioxide, 5wt%-10wt% of barium sulfate and 5wt%-10wt% of polytetrafluoroethylene.

4. A high-efficiency moisture-absorbing and cooling coating according to claim 2 or 3, characterized in that: The refractive index of the barium sulfate is 1.5, and the refractive index of the radiation cooling functional resin is less than 1.

5. The high-efficiency moisture-absorbing and cooling coating according to claim 1, characterized in that: The hygroscopic filler includes any one or more of lithium bromide, lithium chloride, magnesium chloride, and calcium chloride.

6. The high-efficiency moisture-absorbing and cooling coating according to claim 1, characterized in that: The radiation cooling functional resin includes fluorocarbon resin.

7. A high-efficiency moisture-absorbing and cooling coating, characterized in that: The invention comprises a porous topcoat resin layer prepared from the high-efficiency moisture-absorbing and cooling coating according to any one of claims 1 to 6.

8. The high-efficiency moisture-absorbing and cooling coating according to claim 7, characterized in that: The invention also comprises a primer resin layer, wherein 30wt%-50wt% of zinc powder and 5wt% of calcium carbonate are distributed in the primer resin layer, and the particle size of the calcium carbonate is 1000-2500 nm.

9. The high-efficiency moisture-absorbing and cooling coating according to claim 8, characterized in that: The thickness of the primer resin layer is 30 μm, and the thickness of the topcoat resin layer is 120-140 μm.

10. A method for preparing a high-efficiency moisture-absorbing and cooling coating, for preparing a high-efficiency moisture-absorbing and cooling coating according to any one of claims 7 to 9, characterized in that: The following steps are involved: Step S1: preparing a moisture-absorbing and cooling coating; Step S11: adding solvents with different evaporation rates to the radiation cooling functional resin and stirring evenly; Step S12: Then, add the radiation refrigeration filler and the hygroscopic filler and stir evenly; Step S13: Finally, 5 wt%-15 wt% water is added, and the stirring speed is 3000-8000 r / min; Step S2: preparing a porous topcoat resin layer; Step S21: applying a moisture-absorbing and cooling coating, and solvents with different evaporation rates evaporate successively to form a film; Step S22: After the topcoat resin layer is solidified, the water evaporates and forms a plurality of holes on the paint surface.

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