A kind of radiation cooling coating and preparation method thereof

Abstract

The present invention discloses a radiant cooling coating and a preparation method thereof, relating to the technical field of energy-saving coatings. The radiant cooling coating comprises: a primer comprising an epoxy zinc-rich varnish and a first near-infrared reflective material, wherein the first near-infrared reflective material / epoxy zinc-rich varnish has a mass ratio of 3 to 6 wt %; and a topcoat comprising a fluorocarbon varnish, a sunlight reflective material, and a second near-infrared reflective material, wherein the average refractive index of the second near-infrared reflective material is at least 0.5 higher than the refractive index of the fluorocarbon varnish; wherein the sunlight reflective material / fluorocarbon varnish has a mass ratio of 10 to 15 wt %; and the second near-infrared reflective material / fluorocarbon varnish has a mass ratio of 7 to 10 wt %. The radiant cooling coating prepared by the present invention has high infrared emissivity and solar reflectivity, and the finished paint has good hardness and wear resistance, and can achieve long-term and stable radiant cooling function.

Description

Technical Field

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

[0002] In extreme weather conditions, existing thermal management technologies, including floor heating, air conditioning, and fans, consume significant energy, hindering the achievement of the "dual carbon" goals. Against this backdrop, spectral manipulation technology has attracted widespread attention. By designing a material's specific spectrum to influence its interaction with light, it alters the energy flow on the surface of an object, enabling efficient thermal management of the surface. While current reflective thermal insulation coatings can achieve thermal management functions such as heat preservation, insulation, and cooling without energy input, they are inefficient and have poor weather resistance, making them inadequate for meeting existing cooling needs.

[0003] Chinese invention patent CN 201810238449.X (publication number CN108250873A) discloses an outdoor all-weather sunlight-reflecting and infrared-radiative cooling coating. By adding micron-sized spherical microbeads, micron-sized metal-plated flakes, and / or micron-sized metal-plated spheres to the coating system and applying them in layers, the metal-plated flakes achieve high sunlight reflectivity and high infrared radiation, thereby achieving a passive cooling effect. However, due to the use of micron-sized metal-plated reflective materials, the invention has a relatively low reflectivity, and the layered coating method also complicates the on-site process. Summary of the Invention

[0004] In order to overcome the technical problems existing in the prior art, the present application provides a radiation cooling paint and a preparation method thereof. The radiation cooling paint is prepared by selecting a specific topcoat, primer and specific additives and ratios. The radiation cooling paint has a high infrared emissivity and solar reflectivity. The finished paint has good hardness and wear resistance, and can achieve long-term and stable radiation cooling function.

[0005] In order to achieve the above technical effects, the technical solution adopted in this application is a radiant cooling paint, comprising:

[0006] A primer comprising an epoxy zinc-rich varnish and a first near-infrared reflective material, wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 3-6 wt %;

[0007] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material, and a second near-infrared reflecting material, wherein the average refractive index of the second near-infrared reflecting material is higher than that of the fluorocarbon varnish by at least 0.5;

[0008] Wherein, in terms of mass ratio, the sunlight reflective material / fluorocarbon varnish = 10-15 wt %;

[0009] The second near-infrared reflective material / fluorocarbon varnish = 7-10 wt %.

[0010] As a preferred solution, the near-first near-infrared reflective material is selected from one or more of calcium carbonate, silicon carbide, metallic silicon powder, and selenium powder.

[0011] Furthermore, the first infrared reflective material is calcium carbonate.

[0012] As a preferred solution, the particle size of the first infrared reflective material is 1000-3000 nm.

[0013] Furthermore, the particle size of the first infrared reflective material is 1000-2500 nm.

[0014] As a preferred solution, based on the mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt%.

[0015] As a preferred solution, the second near-infrared reflective material is selected from one or more of barium sulfate, polytetrafluoroethylene, hollow glass microspheres, red iron oxide, copper oxide, yellow iron oxide, and zinc selenide.

[0016] Furthermore, the second near-infrared reflective material is a mixture of barium sulfate and polytetrafluoroethylene.

[0017] Furthermore, the particle size of the barium sulfate is 550-1000 nm, and the particle size of the polytetrafluoroethylene is 1-2.5 μm.

[0018] As a preferred solution, the sunlight reflecting material is selected from one or more of titanium dioxide, zinc oxide, barium titanate, metal aluminum powder, and metal silver powder.

[0019] As a preferred solution, the particle size of the sunlight reflecting material is 300-600 nm.

[0020] Furthermore, the sunlight reflecting material is titanium dioxide.

[0021] Furthermore, the particle size of the titanium dioxide is 350-550 nm.

[0022] The present application also provides a method for preparing a radiant cooling coating, comprising the following steps:

[0023] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material to a high-speed disperser, disperse at a linear speed of 10 to 30 m / s for 20 to 120 minutes to obtain a slurry, and filter through an 80 to 100 mesh sieve to obtain a primer layer;

[0024] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse for 20 to 120 minutes at a linear speed of 10 to 30 m / s to obtain a slurry, and filter through an 80 to 100 mesh sieve to obtain a topcoat layer;

[0025] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0026] Technical advantages of this application:

[0027] 1. The technical solution of this application uses multi-component and multi-particle size materials to exhibit excellent reflective performance in different bands. By selecting materials, the refractive index difference between the varnish and the second near-infrared reflective material is controlled to be greater than 0.5, which can further increase the reflectivity in the infrared band and enhance the cooling effect.

[0028] 2. Use epoxy zinc-rich varnish as a specific primer material and fluorocarbon varnish as a specific topcoat material. Due to its local ionic bond characteristics, the fluorocarbon bond can form a Zn-FC covalent bond with the zinc element in the epoxy zinc-rich varnish, further improving the stability of the paint material;

[0029] 3. Epoxy zinc-rich varnish is rich in zinc, so it has a cathodic protection effect on the steel substrate. Its paint film has good toughness and is easy to construct. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is the reflectivity curve of the radiant cooling coating provided in Example 1 of the present application; Figure 2 This is the emissivity curve of the radiative cooling coating provided in Example 1 of the present application. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0035] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the product of this application is typically placed when in use. These terms are intended solely to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0036] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "connected," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0037] It should be noted that, in the absence of conflict, different features in the embodiments of the present application can be combined with each other.

[0038] In order to solve the problems in the prior art, the present application provides a radiant cooling coating, comprising:

[0039] A primer comprising an epoxy zinc-rich varnish and a first near-infrared reflective material, wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 3-6 wt %;

[0040] Epoxy zinc-rich varnish has good adhesion, weather resistance and corrosion resistance, and can provide a long-life, corrosion-resistant primer for radiant cooling coatings;

[0041] First, near-infrared reflective materials can effectively reflect near-infrared radiation. Near-infrared radiation is one of the main parts of solar radiation that causes temperature rise. Reflecting infrared radiation can effectively achieve a cooling effect.

[0042] The mass ratio of the first near-infrared reflective material to the epoxy zinc-rich varnish is 3-6 wt%. This ratio achieves good near-infrared reflectivity while not affecting the basic performance of the primer. If the ratio of the first infrared reflective material is too low, a good cooling effect cannot be achieved. If the ratio of the first infrared reflective material is too high, the coating performance of the primer will be affected.

[0043] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material, and a second near-infrared reflecting material, wherein the average refractive index of the second near-infrared reflecting material is higher than that of the fluorocarbon varnish by at least 0.5;

[0044] The fluorocarbon varnish selected in the topcoat is a high-performance coating with excellent weather resistance, corrosion resistance, chemical resistance and self-cleaning properties. As the main component of the topcoat, it can protect the effective primer. At the same time, the fluorocarbon bond contained in the topcoat, due to its local ionic bond characteristics, can form a Zn-FC covalent bond with the zinc element in the epoxy zinc-rich epoxy, further improving the stability and weather resistance of the paint material.

[0045] Solar reflective materials are mainly used to reflect visible light and some ultraviolet radiation, reducing the heating effect of radiation on the surface of objects and further improving the cooling effect;

[0046] The second near-infrared reflective material has a similar function to the first near-infrared reflective material in the primer, effectively reflecting radiation in the near-infrared band and reducing the temperature. The second near-infrared reflective material in the topcoat needs to have a higher refractive index and reflection efficiency to further enhance the cooling effect. Therefore, the average refractive index of the second infrared reflective material needs to be higher than that of the fluorocarbon varnish by at least 0.5. This difference helps to further enhance the refraction effect of near-infrared radiation and improve the radiation cooling performance of the coating to ensure the cooling effect.

[0047] Wherein, in terms of mass ratio, the sunlight reflective material / fluorocarbon varnish = 10-15 wt %;

[0048] The second near-infrared reflective material / fluorocarbon varnish = 7-10 wt %;

[0049] The second near-infrared reflective material in the topcoat is more than that in the primer, because the topcoat is directly exposed to the radiation in the atmosphere. A higher content of near-infrared reflective material can effectively improve the radiation refraction efficiency and achieve a better cooling effect.

[0050] Preferably, the first near-infrared reflecting material / epoxy zinc-rich varnish can be any value of 3 to 6 wt %, including but not limited to 3.5 wt %, 4 wt %, 5 wt %. Sunlight reflecting material / fluorocarbon varnish can be any value of 10 to 15 wt %, including but not limited to 11 wt %, 12 wt %, 14 wt %. The second near-infrared reflecting material / fluorocarbon varnish can be any value of 7 to 10 wt %, including but not limited to 8 wt %, 9 wt %, 9.5 wt %.

[0051] In one embodiment, the near-first near-infrared reflective material is selected from one or more of calcium carbonate, silicon carbide, metallic silicon powder, and selenium powder. These materials have the property of reflecting light within the near-infrared band. Near-infrared light is an electromagnetic wave between visible light and mid-infrared light, with a wavelength range of approximately 700 to 2500 nanometers. These materials all have excellent reflectivity and stability in the near-infrared band.

[0052] For example, the first infrared reflective material is calcium carbonate, which is a common inorganic compound with high whiteness, certain infrared reflective ability, and relatively low cost.

[0053] As a preferred embodiment, the particle size of the first infrared reflective material is 1000-3000 nm. For example, the first infrared reflective material in the coating can have multiple particle sizes, such as a mixture of particles of 1000, 1500, 2000, 2500, and 3000 nm. Larger particle sizes allow the first infrared reflective material particles to have a larger surface area and a more complex surface structure, which helps enhance interaction with infrared light and thus improve reflection efficiency. Smaller particle sizes make them easier to disperse in the primer, improving the overall uniformity of the coating. Therefore, in coatings, a mixture of large and small particle sizes is more conducive to improving the overall performance of the coating.

[0054] Preferably, the particle size of the first infrared reflective material is 1000-2500 nm. By further narrowing the particle size range, the infrared reflective performance of the material can be more accurately controlled, reducing performance fluctuations caused by excessive particle size differences.

[0055] Preferably, in terms of mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %.

[0056] As a preferred embodiment, the second near-infrared reflective material is selected from one or more of barium sulfate, polytetrafluoroethylene, hollow glass microspheres, red iron oxide, copper oxide, yellow iron oxide, and zinc selenide. The above materials can effectively reflect radiation in the near-infrared light band (usually referring to light with a wavelength between 700 and 2500 nm).

[0057] Furthermore, the second near-infrared reflective material is a mixture of barium sulfate and polytetrafluoroethylene.

[0058] Furthermore, the particle size of the barium sulfate is 550-1000 nm, and the particle size of the polytetrafluoroethylene is 1-2.5 μm.

[0059] Preferably, the particle size of the barium sulfate can be any value between 550-1000 nm, including but not limited to 600 nm, 800 nm, and 900 nm.

[0060] As a preferred solution, the sunlight reflecting material is selected from one or more of titanium dioxide, zinc oxide, barium titanate, metal aluminum powder, and metal silver powder.

[0061] As a preferred embodiment, the particle size of the sunlight reflective material is 300-600 nm. The particle size of the sunlight reflective material can be any value between 300 and 600 nm, including but not limited to 350 nm, 450 nm, and 500 nm.

[0062] Furthermore, the sunlight reflecting material is titanium dioxide.

[0063] Furthermore, the particle size of the titanium dioxide is 350-550 nm.

[0064] The present application also provides a method for preparing a radiant cooling coating, comprising the following steps:

[0065] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material to a high-speed disperser, disperse at a linear speed of 10 to 30 m / s for 20 to 120 minutes to obtain a slurry, and filter through an 80 to 100 mesh sieve to obtain a primer layer;

[0066] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse for 20 to 120 minutes at a linear speed of 10 to 30 m / s to obtain a slurry, and filter through an 80 to 100 mesh sieve to obtain a topcoat layer;

[0067] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0068] The present application scheme is further explained below with reference to specific embodiments. Specific embodiments

[0069] Example 1

[0070] A method for preparing a radiant cooling coating comprises the following steps:

[0071] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1000 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 3 wt %;

[0072] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (titanium dioxide with a particle size of 300 nm), and a second near-infrared reflecting material (barium sulfate with a particle size of 550 nm), wherein the average refractive index of the second near-infrared reflecting material is 1 higher than the refractive index of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 10 wt %, and the second near-infrared reflecting material / fluorocarbon varnish = 7 wt %.

[0073] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 10 m / s for 20 min to obtain a slurry, and filter through an 80-mesh sieve to obtain a primer layer;

[0074] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 10 m / s for 20 min to obtain a slurry, and filter through an 80-mesh sieve to obtain a topcoat layer;

[0075] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0076] The radiant cooling coating obtained in Example 1 was tested. The test results are shown in Figure 1 、 Figure 2 The prepared radiant cooling coating has high emissivity and reflectivity.

[0077] Example 2

[0078] A method for preparing a radiant cooling coating comprises the following steps:

[0079] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1500 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5wt%;

[0080] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (zinc oxide with a particle size of 400 nm), and a second near-infrared reflecting material (barium sulfate), wherein the average refractive index of the second near-infrared reflecting material is 0.8 higher than that of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 13 wt %, and the second near-infrared reflecting material / fluorocarbon varnish = 8 wt %.

[0081] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a primer layer;

[0082] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a topcoat layer;

[0083] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0084] Example 3

[0085] A method for preparing a radiant cooling coating comprises the following steps:

[0086] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 3000 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 3-6 wt %;

[0087] The topcoat includes a fluorocarbon varnish, a sunlight reflecting material (titanium dioxide with a particle size of 600 nm), and a second near-infrared reflecting material (barium sulfate), wherein the average refractive index of the second near-infrared reflecting material is 0.7 higher than the refractive index of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 15 wt %, the second near-infrared reflecting material / fluorocarbon varnish = 10 wt %.

[0088] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 30 m / s for 120 min to obtain a slurry, and filter through a 100-mesh sieve to obtain a primer layer;

[0089] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 30 m / s for 120 min to obtain a slurry, and filter through a 100-mesh sieve to obtain a topcoat layer;

[0090] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0091] Example 4

[0092] This embodiment is basically the same as Embodiment 2, except that the second near-infrared reflective material is a mixture of barium sulfate and polytetrafluoroethylene, and the mass ratio of barium sulfate to polytetrafluoroethylene is 1:1.

[0093] A method for preparing a radiant cooling coating comprises the following steps:

[0094] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1500 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %;

[0095] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (zinc oxide with a particle size of 400 nm), and a second near-infrared reflecting material (barium hydroxide and polytetrafluoroethylene in a mass ratio of 1:1), wherein the average refractive index of the second near-infrared reflecting material is 0.8 higher than that of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 13 wt %, the second near-infrared reflecting material / fluorocarbon varnish = 8 wt %.

[0096] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a primer layer;

[0097] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a topcoat layer;

[0098] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0099] Example 5

[0100] A method for preparing a radiant cooling coating comprises the following steps:

[0101] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (selenium powder with a particle size of 2000 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5wt%;

[0102] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (metallic silver powder with a particle size of 500 nm), and a second near-infrared reflecting material (red iron oxide), wherein the average refractive index of the second near-infrared reflecting material is 0.6 higher than that of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 13 wt %; the second near-infrared reflecting material / fluorocarbon varnish = 9 wt %.

[0103] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 15 m / s for 70 min to obtain a slurry, and filter through an 80-mesh sieve to obtain a primer layer;

[0104] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 80 min to obtain a slurry, and filter through an 80-mesh sieve to obtain a topcoat layer;

[0105] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0106] Comparative Example 1

[0107] This comparative example is basically the same as Example 4, except that the average refractive index of the second near-infrared reflective material is 0.3 higher than the refractive index of the fluorocarbon varnish.

[0108] A method for preparing a radiant cooling coating comprises the following steps:

[0109] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1500 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %;

[0110] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (zinc oxide with a particle size of 400 nm), and a second near-infrared reflecting material (barium hydroxide and polytetrafluoroethylene in a mass ratio of 1:1), wherein the average refractive index of the second near-infrared reflecting material is 0.3 higher than that of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 13 wt %, the second near-infrared reflecting material / fluorocarbon varnish = 8 wt %.

[0111] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a primer layer;

[0112] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a topcoat layer;

[0113] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0114] Comparative Example 2

[0115] This comparative example is basically the same as Example 2, except that the fluorocarbon varnish is replaced by ester glue varnish.

[0116] A method for preparing a radiant cooling coating comprises the following steps:

[0117] Raw materials: primer, the primer comprising epoxy zinc-rich varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1500 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %;

[0118] A topcoat comprising an ester adhesive varnish, a sunlight reflecting material (zinc oxide with a particle size of 400 nm), and a second near-infrared reflecting material (barium hydroxide and polytetrafluoroethylene in a mass ratio of 1:1), wherein the average refractive index of the second near-infrared reflecting material is 0.8 higher than that of the ester adhesive varnish. In terms of mass ratio, the sunlight reflecting material / ester adhesive varnish = 13 wt %, and the second near-infrared reflecting material / ester adhesive varnish = 8 wt %.

[0119] 1. Preparation of primer: Add water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a primer layer;

[0120] 2. Preparation of topcoat: Add water, ester glue varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a topcoat layer;

[0121] 3. Combine primer and topcoat to get multi-layer radiant cooling coating.

[0122] Comparative Example 3

[0123] This comparative example is basically the same as Example 2, except that the epoxy zinc-rich varnish is replaced by ordinary epoxy varnish.

[0124] A method for preparing a radiant cooling coating comprises the following steps:

[0125] Raw materials: primer, which includes ordinary epoxy varnish and a first near-infrared reflective material (metal silicon powder with a particle size of 1500 nm), wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %;

[0126] A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material (zinc oxide with a particle size of 400 nm), and a second near-infrared reflecting material (barium hydroxide and polytetrafluoroethylene in a mass ratio of 1:1), wherein the average refractive index of the second near-infrared reflecting material is 0.8 higher than that of the fluorocarbon varnish, and by mass ratio, the sunlight reflecting material / fluorocarbon varnish = 13 wt %, the second near-infrared reflecting material / fluorocarbon varnish = 8 wt %.

[0127] 1. Preparation of primer: Add water, ordinary epoxy varnish, and the first near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a primer layer;

[0128] 2. Preparation of topcoat: Add water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, disperse at a linear speed of 20 m / s for 60 min to obtain a slurry, and filter through a 90-mesh sieve to obtain a topcoat layer;

[0129] 3. Combine primer and topcoat to get multi-layer radiant cooling coating. Example

[0130] The radiant cooling coatings prepared in Example 2, Examples 4-5 and Comparative Examples 1-3 were tested. The coating thickness was 1 mm. The reflectivity, adhesion, cooling effect and average radiant cooling power were tested. The test method was as follows:

[0131] Total infrared emissivity: The sample coated with the radiative cooling coating is passed through a Fourier transform infrared spectrometer (FTIR) equipped with an integrating sphere to measure the total infrared emissivity.

[0132] Adhesion: Apply radiant cooling paint to a sandblasted steel plate measuring 150mm x 70mm x 4mm and cure for 168 hours. Perform a tape tear test in accordance with GB / T9286-1998. Use a single-edged tool to make three cuts parallel and perpendicular to the long edge of the plate, with a 3mm interval between each cut and a grid of four. The highest score is 0, and the lowest is 5.

[0133] Cooling effect: The time taken for metal plates of the same specifications (150mm×70mm×4mm) coated with radiation paint to cool to 30 degrees after being heated to 75 degrees Celsius at the same room temperature.

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136] Sample Overall infrared radiation rate / % Adhesion Cooling effect / s Example 2 93.5% Level 1 268 Example 4 94.1% Level 0 255 Example 5 92.6% Level 0 283 Comparative Example 1 90.5% Level 1 329 Comparative Example 2 93.8% Level 2 273 Comparative Example 3 93.0% Level 2 310

[0137] Observing Table 1, it can be seen that Example 4 has the best comprehensive performance. Comparing Example 2 with Example 4, it can be seen that using a mixture of barium sulfate and polytetrafluoroethylene as the second near-infrared reflective material can significantly increase the infrared emissivity, thereby improving the cooling effect; comparing Example 4 with Comparative Example 1, it can be seen that when the average refractive index of the second near-infrared reflective material is higher than the refractive index of the fluorocarbon varnish by 0.3, the infrared reflectivity and the cooling effect are both reduced; comparing Example 4 with Comparative Example 2, after replacing the fluorocarbon varnish with the ester glue varnish, the adhesion of the coating decreases, which may be because the fluorocarbon varnish can form a Zn-FC covalent bond with the zinc element in the epoxy zinc-rich varnish, further improving the stability of the paint material, while the ester glue varnish cannot play this role; comparing Example 4 with Comparative Example 3, after replacing the epoxy zinc-rich varnish with the ordinary epoxy varnish, the adhesion also decreases, and the cooling effect becomes worse.

[0138] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A radiation cooling paint, characterized in that: include A primer comprising an epoxy zinc-rich varnish and a first near-infrared reflective material, wherein, by mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 3-6 wt %; A topcoat comprising a fluorocarbon varnish, a sunlight reflecting material, and a second near-infrared reflecting material, wherein the average refractive index of the second near-infrared reflecting material is higher than that of the fluorocarbon varnish by at least 0.5; Wherein, in terms of mass ratio, the sunlight reflective material / fluorocarbon varnish = 10-15 wt %; The second near-infrared reflective material / fluorocarbon varnish = 7-10 wt %.

2. The radiant cooling paint according to claim 1, characterized in that: The first near-infrared reflective material is selected from one or more of calcium carbonate, silicon carbide, metallic silicon powder, and selenium powder.

3. The radiant cooling paint according to claim 1, characterized in that: The particle size of the first near-infrared reflective material is 1000-3000 nm.

4. The radiant cooling paint according to claim 1, characterized in that: In terms of mass ratio, the first near-infrared reflective material / epoxy zinc-rich varnish = 5 wt %.

5. The radiant cooling paint according to claim 1, characterized in that: The second near-infrared reflective material is selected from one or more of barium sulfate, polytetrafluoroethylene, hollow glass microspheres, red iron oxide, copper oxide, yellow iron oxide, and zinc selenide.

6. The radiant cooling paint according to claim 1, characterized in that: The sunlight reflecting material is selected from one or more of titanium dioxide, zinc oxide, barium titanate, metal aluminum powder, and metal silver powder.

7. The radiant cooling paint according to claim 1, characterized in that: The particle size of the sunlight reflecting material is 300-600 nm.

8. The method for preparing a radiant cooling coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: Preparation of primer: adding water, epoxy zinc-rich varnish, and the first near-infrared reflective material into a high-speed disperser, dispersing to obtain a slurry, and filtering to obtain a primer layer; Preparation of topcoat: adding water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, dispersing to obtain a slurry, filtering to obtain a topcoat layer; By combining primer and topcoat, you can get a multi-layer radiant cooling coating.

9. The method for preparing a radiant cooling coating according to claim 8, characterized in that: The primer is prepared by adding water, epoxy zinc-rich varnish, and a first near-infrared reflective material into a high-speed disperser, dispersing for 20 to 120 minutes at a linear speed of 10 to 30 m / s to obtain a slurry, and filtering through an 80 to 100 mesh sieve to obtain a primer layer.

10. The method for preparing a radiant cooling coating according to claim 8, characterized in that: The topcoat is prepared by adding water, fluorocarbon varnish, sunlight reflective material, and second near-infrared reflective material into a high-speed disperser, dispersing for 20 to 120 minutes at a linear speed of 10 to 30 m / s to obtain a slurry, and filtering through an 80 to 100 mesh sieve to obtain a topcoat layer.

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