A high-durability self-cleaning reflective heat-insulating coating and its preparation method

Abstract

This invention discloses a high-durability, self-cleaning reflective thermal insulation coating and its preparation method. The coating is prepared using a specially designed and synthesized grafted modified silicone resin combined with fluorocarbon resin, high-reflectivity filler, and thermal insulation filler. By introducing coupled polysiloxane segments with numerous amide structures and end-capped with catechol groups into the cured segments of the fluorocarbon coating in a grafted and suspended state, highly stable microphase separation of the coating system is achieved, effectively improving the matrix density and coating adhesion. Combined with the original strong reflective thermal insulation performance, this results in ultra-high durability and self-cleaning properties. This technology has a clear mechanism of action, a simple production process, and excellent performance, making it suitable for large-scale production. It enables the coating to maintain its long-term reflective thermal insulation and temperature control performance under complex and harsh environments, which is of great significance for green and sustainable temperature control and protection of buildings and engineering structures in various complex environments.

Description

Technical Field

[0002] This invention belongs to the field of fine polymer materials, specifically relating to the preparation, application, and use in the field of temperature control and protection of building and infrastructure structural surfaces of a high-durability self-cleaning reflective heat-insulating coating material. Background Technology

[0004] With the continuous development of my country's economy and society, green and sustainable development has become the mainstream direction of development, and related green and energy-saving technologies have become one of the research hotspots. Building structures, especially large spatial structures, large tanks, or large-volume structures, have high demands for structural temperature control. Traditional thermal management methods, mainly through active heating or cooling technologies, generate significant energy consumption and waste. Using temperature-controlling materials on structural surfaces is a common passive thermal management method that can greatly reduce temperature control energy consumption and improve structural performance. For building and engineering structures exposed to the environment, the photothermal conversion of solar radiation on the structural surface is the most important factor affecting temperature changes. Therefore, temperature-controlling materials based on reflected radiation cooling are an excellent sustainable temperature control technology, characterized by thinness, high efficiency, and environmental friendliness.

[0005] Reflective thermal insulation and temperature control materials come in various forms. Initially, they were mainly used in the form of sheets or films, such as light-colored natural stone sheets, highly reflective metal sheets (e.g., aluminum, silver), and thin films with highly reflective coatings (e.g., aluminum- or silver-plated polyimide films). These materials have excellent reflective properties and good temperature control, but they are costly and require stringent construction techniques, thus limiting their application to specialized fields such as aerospace and military. Therefore, to reduce material costs and improve the ease of construction and applicability of reflective thermal insulation materials in building and engineering structures, reflective thermal insulation coatings, made by adding high-reflectivity fillers and pigments to coating resins, have gradually become the mainstream reflective thermal insulation material. These coatings can be applied to various structural surfaces and cured to form a thin-layer structure with high reflective thermal insulation performance. In the current context of energy conservation, environmental protection, and green development, reflective thermal insulation coatings have demonstrated their potential value and relevant national and industry standards have been established.

[0006] Currently, numerous researchers have conducted research and development on reflective heat-insulating coating technology. For example, patent CN117363128A discloses an exterior wall reflective heat-insulating coating and its preparation method. This coating, using materials such as silicone-acrylic emulsion, rutile titanium dioxide, modified hollow glass microspheres, and aerogel powder, produces a reflective heat-insulating coating with excellent heat insulation performance and heat reflection capabilities. Patent CN116851235B discloses a reflective heat-insulating multicolor coating, its preparation method, and its application. This coating uses a composite of SiO2 aerogel, hollow glass microspheres, and hollow ceramic microspheres as the heat-insulating filler in a barrier-type heat-insulating coating, infrared reflective pigments as the heat-insulating filler in a reflective heat-insulating coating, and organic reflective pigments as multicolor pigments. This results in a multicolor coating with high barrier properties and high reflectivity, exhibiting good solar reflectivity and near-infrared reflectivity.

[0007] While the aforementioned studies have made some progress in the preparation of reflective heat-insulating coatings, their superior reflective heat-insulating and temperature-controlling performance is mainly tested when the coating is in good condition after preparation. Unlike the protective performance of conventional coatings, the temperature-controlling performance of reflective heat-insulating coatings, especially their light reflection and radiation performance, depends primarily on their external surface properties. Because they operate in exposed environments, on the one hand, under the long-term effects of ultraviolet radiation, heat and oxygen, rainwater, acids, alkalis, and salts, the coating often exhibits significant aging phenomena, such as discoloration, cracking, chalking, and blistering. On the other hand, the coating is also easily affected by environmental contaminants such as dust and oil during service, leading to surface obscuring. Under these conditions, the reflective temperature-controlling effect of the reflective heat-insulating coating is often significantly reduced. Aging and dirt accumulation are also the main reasons why conventional reflective heat insulation coatings fail to achieve the expected results in actual service. Therefore, considering their self-cleaning ability and long-term durability is the key direction for the development of reflective heat insulation coatings. For example, patents CN118460041A and CN111019445B have both studied the self-cleaning and high durability of reflective heat insulation coatings.

[0008] Overall, it is evident that the durability and self-cleaning ability of reflective heat-insulating coatings are crucial for ensuring their temperature control performance during service. While some related research exists, its focus is relatively weak, and the maturity of related products is still low. Therefore, conducting research to effectively improve the durability and self-cleaning ability of reflective heat-insulating coatings, and ultimately obtain reflective heat-insulating coatings with superior performance, is of great significance for the technological advancement and widespread application of green coatings. Summary of the Invention

[0010] The purpose of this invention is to solve the above-mentioned problems, provide a high-durability self-cleaning reflective heat-insulating coating, and provide its preparation, construction and application methods.

[0011] The high-durability self-cleaning reflective heat-insulating coating of this invention is composed of component A resin and component B curing agent. Component A, the main agent, is prepared by mixing fluorocarbon resin, special grafted modified silicone resin, high-reflectivity filler, heat-insulating filler, solvent, and functional additives. Component B, the curing agent, is prepared by isocyanate and solvent. The structural formula of the special grafted modified silicone resin is shown in the figure below.

[0012]

[0013] In the formula, n = 20~60; the mass ratio of special grafted modified silicone resin to fluorocarbon resin is 1: (5~10); and the mass ratio of component A resin to component B curing agent is 1: (0.08~0.15).

[0014] The A component of this high-durability self-cleaning reflective heat-insulating coating contains 45%~55% fluorocarbon resin, 5%~10% special grafted modified silicone resin, high-reflectivity filler, heat-insulating filler, solvent, and functional additives, respectively, based on the total mass of component A. The fluorocarbon resin is at least one of solvent-based polyvinylidene fluoride resin, polychlorotrifluoroethylene-vinyl ether resin, and polychlorotetrafluoroethylene-vinyl ether resin. The high-reflectivity filler is at least one of rutile titanium dioxide, potassium hexatitanate whiskers, and far-infrared ceramic powder. The heat-insulating filler is at least one of hollow glass microspheres, ceramic hollow microspheres, and silica aerogel. The solvent is at least one of xylene, acetone, n-butanol, butyl acetate, dimethylformamide, and cyclic ether. The functional additives are at least one of dispersant, defoamer, leveling agent, rheology modifier, ultraviolet absorber, and antioxidant.

[0015] In the curing agent of component B of this high-durability self-cleaning reflective heat-insulating coating, the content of isocyanate and solvent is 85%~100% and 0~15% respectively, based on the total mass of component B; wherein the isocyanate is at least one selected from toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, terephthalic diisocyanate, phenyl diisocyanate, toluene diisocyanate trimer, hexamethylene diisocyanate trimer, and hexamethylene diisocyanate biuret; wherein the solvent is at least one selected from xylene, acetone, n-butanol, butyl acetate, dimethylformamide, and cyclic ether.

[0016] The preparation method of the special grafted modified silicone resin in this high-durability self-cleaning reflective heat-insulating coating includes the following steps:

[0017] (1) Dissolve an appropriate amount of DL-homocysteine ​​thiolactone hydrochloride and sodium bicarbonate in an ethanol / water (1:1) mixed solvent. Add acryloyl chloride dropwise to the solution under low temperature conditions. The molar ratio of acryloyl chloride, DL-homocysteine ​​thiolactone hydrochloride and sodium bicarbonate is 1.05:1:2.2. After the addition is completed, react at room temperature for 2 hours. Dilute the reaction solution with saturated brine and extract with ethyl acetate. Dry the extract by rotary evaporation to obtain acrylamide thiolactone (AMA).

[0018] (2) Dissolve an appropriate amount of acrylamide thiolactone in 1,4-dioxane, add 3-mercapto-1-propanol and triethylamine to the solution, and react at room temperature for 8 h to obtain the addition product AMA-OH. Then add bis(3-aminopropyl)-terminated polydimethylsiloxane to the reaction solution and react at room temperature for 5 h to obtain the ring-opening product AMA-P of amino group and thiolactone. The molar ratio of acrylamide thiolactone, 3-mercapto-1-propanol and bis(3-aminopropyl)-terminated polydimethylsiloxane is 1:1:1, and the concentration of triethylamine is 5%.

[0019] (3) N,N'-methylenebisacrylamide was added to AMA-P solution, wherein the molar ratio of AMA-P to N,N'-methylenebisacrylamide was 2:1. The reaction was carried out at room temperature for 3 hours to obtain the coupling product DAMA-P. Dopamine methacrylamide was then added and the reaction was carried out at 50°C for 12 hours to obtain the addition product DAMA-P-DOPA solution, wherein the molar ratio of DAMA-P to dopamine methacrylamide was 1:4.2. The solvent was removed by rotary evaporation of DAMA-P-DOPA solution to obtain the special grafted modified silicone resin.

[0020] The preparation method of the A-component resin and B-component curing agent of this high-durability self-cleaning reflective heat insulation coating includes the following steps:

[0021] (1) Preparation of component A: Weigh appropriate amounts of each component, add fluorocarbon resin, special grafted modified silicone resin, high reflectivity filler and functional additives to a high-speed disperser in sequence, disperse the mixture at high speed for 30 min to 40 min until the system is uniform; then add the mixture to a sand mill and grind for 2 h to 3 h, then add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add solvent and high heat insulation filler to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain component A of the coating.

[0022] (2) Preparation of component B curing agent: The curing agent and solvent are dispersed and mixed for 30 min to 40 min until the system is homogeneous and stable to obtain the component B curing agent of the coating.

[0023] The dispersion conditions in the high-speed disperser of the high-durability self-cleaning reflective heat-insulating coating preparation method are: temperature 40 ℃~60 ℃, linear velocity 6 m / s~10 m / s; grinding conditions in the ball mill are: linear velocity 6 m / s~10 m / s, grinding bead amount 75%~80%; dispersion conditions in the dispersion kettle are: room temperature environment, linear velocity 2 m / s~3 m / s.

[0024] This high-durability self-cleaning reflective heat insulation coating requires the A component main agent and the B component curing agent to be mixed evenly according to the specified formula before application. The dry film thickness of the reflective heat insulation coating after application is 120 μm-200 μm. The application method can be any of spraying, roller coating, or brushing.

[0025] The positive effects of the high-durability self-cleaning reflective heat-insulating coating of the present invention are:

[0026] The high-durability self-cleaning reflective heat-insulating coating prepared in this invention is made using a specially designed and synthesized grafted modified silicone resin combined with fluorocarbon resin, high-reflectivity filler, heat-insulating filler, and other components. The specially grafted modified silicone resin introduces polydimethylsiloxane segments with four catechol-terminated coupling structures into the curing segments of the fluorocarbon coating in a grafted, suspended state. Due to the high flexibility of the polydimethylsiloxane segments, they undergo in-situ microphase separation with the rigid fluorocarbon resin segments during curing, resulting in a nanoscale heterogeneous structure. Furthermore, the introduction of a large number of catechol groups at the ends of the grafted chains significantly enhances the interaction between the polydimethylsiloxane segments and the filler, effectively improving the overlap and arrangement of the phase-separated structure and the filler. The process achieves nanoscale microphase separation and volumetric overlap with micron-fillers, resulting in a micro-nano composite structure on the surface. Furthermore, the low surface energy of silicone and fluorocarbon resins contributes to the coating's strong hydrophobic properties, making it difficult for stains to adhere and enhancing its resistance to dirt. The special grafted modified silicone resin utilizes materials such as N,N-methylenebisacrylamide and thiolactone, containing numerous amide groups that provide abundant hydrogen bonding between chain segments. This effectively improves the mechanical properties of the cured body and solidifies the phase separation process. Combined with the strong internal binding effect from numerous catechol groups, the coating exhibits extremely high density, making it difficult for stains to penetrate. Its weak adhesion allows for easy cleaning even under rain conditions. These combined factors result in exceptional self-cleaning properties, effectively preventing dirt accumulation on the coating surface during long-term service in various environments, while also allowing the coating's photothermal properties to be fully utilized.

[0027] Furthermore, since the fluorocarbon resin and silicone resin used in the coating have extremely strong weather resistance, the coating itself has excellent UV aging resistance. The coating's density and non-fouling properties also significantly improve its corrosion resistance compared to conventional coatings. Therefore, the prepared coating has strong overall durability and can maintain its service life in various complex and harsh environments such as high altitudes and coastal areas, truly achieving the expected long-term temperature control and protection effect.

[0028] In summary, this technology has a clear mechanism of action, a simple production process, and excellent performance, making it suitable for large-scale production. It is of great significance for achieving long-term and sustainable temperature control of houses, factories, and large infrastructure in outdoor exposed environments, especially in harsh and complex environments. Attached Figure Description

[0030] Figure 1 This is the synthesis equation for a special grafted modified silicone resin. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to specific embodiments.

[0033] Example 1: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A1 component resin and B1 component curing agent is as follows:

[0034] (1) Weigh 50 parts of polychlorotrifluoroethylene-vinyl ether resin, 7 parts of special grafted modified silicone resin, 16.5 parts of rutile titanium dioxide, 1 part of dispersant, 0.5 parts of leveling agent and 1 part of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 11 parts of xylene and 13 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A1 component of the coating.

[0035] (2) Disperse and mix 94 parts of isophorone diisocyanate and 6 parts of xylene using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B1 component curing agent of the coating.

[0036] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A1 resin to B1 curing agent of 1:0.12. After being mixed evenly by mechanical stirring, it can be applied.

[0037] Example 2: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A2 component resin and B2 component curing agent is as follows:

[0038] (1) Weigh 48 parts of polyvinylidene fluoride resin, 5.5 parts of special grafted modified silicone resin, 19.5 parts of potassium hexatitanate whiskers, 1 part of leveling agent, 0.5 parts of defoamer, 1.3 parts of antioxidant and 0.7 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 11.5 parts of butyl acetate, 6 parts of silica aerogel and 6 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A2 component of the coating.

[0039] (2) 88 parts of dicyclohexylmethane diisocyanate and 12 parts of butyl acetate were dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system was homogeneous and stable to obtain the B2 component curing agent of the coating.

[0040] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A2 resin to B2 curing agent of 1:0.13. After being mixed evenly by mechanical stirring, it can be applied.

[0041] Example 3: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A3 component resin and B3 component curing agent is as follows:

[0042] (1) Weigh 52 parts of polytetrafluoroethylene-vinyl ether resin, 6 parts of special grafted modified silicone resin, 10 parts of rutile titanium dioxide, 5.5 parts of far-infrared ceramic powder, 1.8 parts of dispersant, 0.8 parts of ultraviolet absorber and 0.9 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 12.5 parts of xylene and 10.5 parts of ceramic hollow microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A3 component of the coating.

[0043] (2) 90 parts of hexamethylene diisocyanate trimer and 10 parts of xylene are dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B3 component curing agent of the coating.

[0044] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A3 resin to B3 curing agent of 1:0.1. After being mixed evenly by mechanical stirring, it can be applied.

[0045] Example 4: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A4 component resin and B4 component curing agent is as follows:

[0046] (1) Weigh 52.5 parts of polychlorotrifluoroethylene-vinyl ether resin, 5 parts of special grafted modified silicone resin, 15 parts of potassium hexatitanate whiskers, 1 part of dispersant, 0.6 parts of leveling agent, 0.3 parts of defoamer and 1.4 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 12.7 parts of acetone, 6.5 parts of silica aerogel and 5 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A4 component of the coating.

[0047] (2) 92.5 parts of isophorone diisocyanate trimer and 7.5 parts of acetone were dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system was homogeneous and stable to obtain the B4 component curing agent of the coating.

[0048] The high-durability self-cleaning reflective heat insulation coating uses an A4 resin to B4 curing agent in a mass ratio of 1:0.11. After being mechanically mixed evenly, it can be applied.

[0049] Example 5: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A5 component resin and B5 component curing agent is as follows:

[0050] (1) Weigh 54 parts of polyvinylidene fluoride resin, 9.5 parts of special grafted modified silicone resin, 15 parts of rutile titanium dioxide, 1 part of leveling agent, 0.4 parts of defoamer, 1 part of ultraviolet absorber and 1.4 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 7.7 parts of dimethylformamide and 10 parts of silica aerogel to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A5 component of the coating.

[0051] (2) 96 parts of hexamethylene diisocyanate trimer and 4 parts of dimethylformamide were dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system was homogeneous and stable to obtain the B5 component curing agent of the coating.

[0052] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A5 resin to B5 curing agent of 1:0.12. After being mixed evenly by mechanical stirring, it can be applied.

[0053] Example 6: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A6 component resin and B6 component curing agent is as follows:

[0054] (1) Weigh 46.5 parts of polytetrafluoroethylene-vinyl ether resin, 8 parts of special grafted modified silicone resin, 7 parts of potassium hexatitanate whiskers, 7 parts of far-infrared ceramic powder, 1.4 parts of defoamer, 1 part of ultraviolet absorber and 0.6 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 13.5 parts of butyl acetate and 15.5 parts of ceramic hollow microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A6 component of the coating.

[0055] (2) Use 100 parts of cyclohexanedimethyl diisocyanate as the curing agent for component B6 of the coating.

[0056] The high-durability self-cleaning reflective heat insulation coating uses an A6 resin to B6 curing agent mass ratio of 1:0.12. After being mechanically mixed evenly, it can be applied.

[0057] Example 7: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A7 component resin and B7 component curing agent is as follows:

[0058] (1) Weigh 47.5 parts of polychlorotrifluoroethylene-vinyl ether resin, 5 parts of special grafted modified silicone resin, 16 parts of far-infrared ceramic powder, 1 part of leveling agent, 0.9 parts of dispersant and 0.9 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 13.2 parts of xylene and 15.5 parts of ceramic hollow microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A7 component of the coating.

[0059] (2) Disperse and mix 90 parts of isophorone diisocyanate trimer and 10 parts of butyl acetate using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B7 component curing agent of the coating.

[0060] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A7 resin to B7 curing agent of 1:0.09. After being mixed evenly by mechanical stirring, it can be applied.

[0061] Example 8: A high-durability self-cleaning reflective heat-insulating coating, the preparation process of its A8 component resin and B8 component curing agent is as follows:

[0062] (1) Weigh 52 parts of polytetrafluoroethylene-vinyl ether resin, 8.5 parts of special grafted modified silicone resin, 10 parts of rutile titanium dioxide, 8 parts of potassium hexatitanate whiskers, 1 part of dispersant, 0.5 parts of defoamer, 1 part of leveling agent and 0.8 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 5.2 parts of acetone and 13 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A8 component of the coating.

[0063] (2) 95 parts of hexamethylene diisocyanate trimer and 5 parts of acetone were dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system was homogeneous and stable to obtain the B8 component curing agent of the coating.

[0064] The high-durability self-cleaning reflective heat insulation coating uses an A8 resin to B8 curing agent mass ratio of 1:0.11. After being mechanically mixed evenly, it can be applied.

[0065] Comparative Example 1: Commercially available protective coatings

[0066] A performance comparison was conducted using a commercially available brand of protective coating.

[0067] Comparative Example 2: Commercially available reflective heat insulation coatings

[0068] A performance comparison was conducted using a commercially available brand of reflective heat insulation coating.

[0069] Comparative Example 3: The preparation process of conventional fluorocarbon resin reflective heat insulation coating, specifically component A9 resin and component B9 curing agent, is as follows:

[0070] (1) Weigh 57 parts of polychlorotrifluoroethylene-vinyl ether resin, 16.5 parts of rutile titanium dioxide, 1 part of dispersant, 0.5 parts of leveling agent and 1 part of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 11 parts of xylene and 13 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A9 component of the coating.

[0071] (2) Disperse and mix 94 parts of isophorone diisocyanate and 6 parts of xylene using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B9 component curing agent of the coating.

[0072] The conventional fluorocarbon resin reflective heat insulation coating uses a mass ratio of A9 resin to B9 curing agent of 1:0.12 during application. The coating is then applied after being thoroughly mixed using mechanical stirring.

[0073] Comparative Example 4: The preparation process of hydroxyl silicone oil modified fluorocarbon reflective heat insulation coating, its A10 component resin and B10 component curing agent are as follows:

[0074] (1) Weigh 50 parts of polychlorotrifluoroethylene-vinyl ether resin, 7 parts of hydroxyl silicone oil, 16.5 parts of rutile titanium dioxide, 1 part of dispersant, 0.5 parts of leveling agent and 1 part of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 11 parts of xylene and 13 parts of hollow glass microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A10 component of the coating.

[0075] (2) Disperse and mix 94 parts of isophorone diisocyanate and 6 parts of xylene using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B10 component curing agent of the coating.

[0076] The hydroxyl silicone oil modified fluorocarbon reflective heat insulation coating is applied with a mass ratio of A10 resin to B10 curing agent of 1:0.12, and the mixture is mechanically stirred until homogeneous before application.

[0077] Comparative Example 5: Acrylamide-grafted silicone resin modified coating, the preparation process of its A11 component resin and B11 component curing agent is as follows:

[0078] (1) In the process of preparing special modified silicone resin, acrylamide modified silicone resin can be obtained by replacing dopamine methylacrylamide with an equal molar amount of acrylamide in the modification reaction.

[0079] (2) Weigh 52 parts of polytetrafluoroethylene-vinyl ether resin, 6 parts of acrylamide-modified silicone resin, 10 parts of rutile titanium dioxide, 5.5 parts of far-infrared ceramic powder, 1.8 parts of dispersant, 0.8 parts of ultraviolet absorber and 0.9 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 12.5 parts of xylene and 10.5 parts of ceramic hollow microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A11 component of the coating.

[0080] (3) Disperse and mix 90 parts of hexamethylene diisocyanate trimer and 10 parts of xylene using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B11 component curing agent of the coating.

[0081] The acrylamide-grafted silicone resin modified coating uses an A11 resin to B11 curing agent in a mass ratio of 1:0.1. After being mechanically mixed evenly, it can be applied.

[0082] Comparative Example 6: Dopamine-grafted non-silicone resin modified coating, the preparation process of its A12 component resin and B12 component curing agent is as follows:

[0083] (1) In the process of preparing special modified silicone resin, dopamine-grafted non-silicone resin can be obtained by replacing bis(3-aminopropyl)-terminated polydimethylsiloxane with hexamethylenediamine in an equal molar amount during the modification reaction.

[0084] (2) Weigh 52 parts of polytetrafluoroethylene-vinyl ether resin, 6 parts of dopamine-grafted non-silicone resin, 10 parts of rutile titanium dioxide, 5.5 parts of far-infrared ceramic powder, 1.8 parts of dispersant, 0.8 parts of ultraviolet absorber and 0.9 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 12.5 parts of xylene and 10.5 parts of ceramic hollow microspheres to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A12 component of the coating.

[0085] (3) Disperse and mix 90 parts of hexamethylene diisocyanate trimer and 10 parts of xylene using a high-speed disperser for 30 min to 40 min until the system is homogeneous and stable to obtain the B12 component curing agent of the coating.

[0086] The dopamine-grafted non-silicone resin modified coating is applied with a mass ratio of A12 resin to B12 curing agent of 1:0.1. After being mixed evenly by mechanical stirring, it can be applied.

[0087] Comparative Example 7: A reflective heat-insulating coating with high special modified silicone resin content, the preparation process of its A13 component resin and B13 component curing agent is as follows:

[0088] (1) Weigh 35 parts of polyvinylidene fluoride resin, 28.5 parts of special grafted modified silicone resin, 15 parts of rutile titanium dioxide, 1 part of leveling agent, 0.4 parts of defoamer, 1 part of ultraviolet absorber and 1.4 parts of rheology modifier and add them to a high-speed disperser in sequence. Disperse the mixture at high speed for 30 min to 40 min until the system is uniform. Then add the mixture to a sand mill and grind for 2 h to 3 h. Add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add 7.7 parts of dimethylformamide and 10 parts of silica aerogel to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain the A13 component of the coating.

[0089] (2) 96 parts of hexamethylene diisocyanate trimer and 4 parts of dimethylformamide were dispersed and mixed using a high-speed disperser for 30 min to 40 min until the system was homogeneous and stable to obtain the B13 component curing agent of the coating.

[0090] The high-durability self-cleaning reflective heat insulation coating uses a mass ratio of A13 resin to B13 curing agent of 1:0.12. After being mixed evenly by mechanical stirring, it can be applied.

[0091] Comparative Example 8: Preparation of reflective heat-insulating coating with high curing agent:

[0092] The A5 component additive and B5 component curing agent from Example 5 were used as the AB components of the coating. During the testing process, the mass ratio of A5 resin to B5 curing agent was 1:0.25.

[0093] Effect description:

[0094] The high-durability self-cleaning reflective heat-insulating coatings prepared in Examples 1-8 of this invention were compared with the comparative coatings of Comparative Examples 1-8 in performance testing. During sample preparation, the thickness of all test coatings was controlled within the range of 120 μm to 200 μm.

[0095] For coatings prepared using appropriate coating materials, performance tests were conducted and compared, including adhesion, solar reflectance, hemispherical emissivity, stain resistance, solar reflectance recovery rate after staining, thermal conductivity, and 6000h artificial UV accelerated aging. Coating adhesion was tested according to the positive tensile test method of GB / T 5210, with a 3mm thick steel plate as the test substrate and a self-made epoxy primer. Solar reflectance and hemispherical emissivity were tested according to JG / T 235. Stain resistance was tested according to GB / T 9780. The solar reflectance recovery rate after staining was calculated using the solar reflectance test results of the coating before and after the stain resistance test. Thermal conductivity was tested according to GB / T 22588. Artificial UV accelerated aging was conducted according to the conditions in GB / T 14522, with a UV aging time of 6000h.

[0096] The relevant test results are summarized in Table 1:

[0097] Table 1. Coating performance test results

[0098] sample Adhesion / MPa Solar reflectance hemispherical emissivity Stain resistance / % Solar reflectance after contamination / % Thermal conductivity / W / (m·K) 6000h Artificial Ultraviolet Accelerated Aging Example 1 10.3 0.92 0.89 95.6 97.2 0.095 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.1%. Example 2 9.8 0.91 0.88 97.3 98.8 0.108 No discoloration, bubbling, or cracking; solar reflectance variation rate is 0.8%. Example 3 9.6 0.91 0.90 96.8 97.6 0.111 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.3%. Example 4 8.7 0.93 0.91 95.4 97.0 0.098 No discoloration, bubbling, or cracking; solar reflectance variation rate is 0.8%. Example 5 11.3 0.90 0.91 94.4 96.3 0.103 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.0%. Example 6 13.7 0.91 0.90 96.3 97.8 0.105 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.2%. Example 7 13.4 0.89 0.89 95.3 96.4 0.106 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.0%. Example 8 12.7 0.92 0.88 94.5 95.8 0.099 No discoloration, bubbling, or cracking; solar reflectance variation rate is 1.5%. Comparative Example 1 4.2 0.45 0.80 35.6 45.3 0.353 Discoloration > 5, severe cracking and powdering, and a change in solar reflectance of 75%. Comparative Example 2 3.5 0.78 0.82 46.2 56.5 0.336 Discoloration level 3, cracking and powdering observed, solar reflectance change rate 68%. Comparative Example 3 5.9 0.85 0.86 66.3 70.8 0.156 Discoloration level 1, slight blistering, no cracking or chalking, solar reflectance change rate 20%. Comparative Example 4 4.9 0.84 0.88 70.8 75.2 0.143 Color change grade 2, no cracking or chalking, solar reflectance change rate 18%. Comparative Example 5 6.8 0.88 0.87 75.9 79.3 0.122 No discoloration, bubbling, or cracking; solar reflectance variation rate is 8.8%. Comparative Example 6 8.2 0.83 0.84 65.5 68.5 0.131 No discoloration, bubbling, or cracking; solar reflectance variation rate is 9.3%. Comparative Example 7 3.8 0.82 0.85 54.2 60.2 0.125 Discoloration level 2, minor bubbling and cracking, solar reflectance change rate 13.6%. Comparative Example 8 6.8 0.86 0.87 82.5 85.6 0.113 No discoloration, bubbling, or cracking; solar reflectance variation rate is 6.8%.

[0099] As can be seen from the data in Table 1, the high-durability self-cleaning reflective heat-insulating coating prepared in the examples exhibits excellent adhesion, reflective radiation performance, heat insulation performance, self-cleaning performance, and aging resistance. This is mainly due to the addition of an appropriate amount of special grafted modified silicone resin. The side-linked silicone resin structure significantly enhances the microphase separation effect of the system and the micro / nano structure effect on the surface. This improves both the self-cleaning performance and the diffuse reflection of sunlight on the coating surface, thus enhancing the reflective heat-insulating performance. Furthermore, the large number of catechol groups introduced into the system significantly improves the system's density and adhesion to the substrate. These properties, combined with the original strong reflective heat-insulating performance of the coating, achieve ultra-high durability and self-cleaning performance, which is of great significance for the long-term durable service of reflective heat-insulating coatings in harsh exposure environments.

[0100] A comparison of the performance of Comparative Examples 1-8 with that of the Examples shows a significant difference in overall performance, especially in the solar reflectance recovery rate after contamination and the degree of accelerated aging under artificial ultraviolet light. This is mainly due to differences in the distribution morphology, microstructure, and the tightness of bonding between the filler structure and the matrix. A detailed analysis follows.

[0101] Comparative Example 1 is a commercially available protective coating. It can be seen that its performance differs significantly from the examples. This is mainly because the commercially available conventional product was not specifically optimized; the quality and quantity of its resin, fillers, and other materials are inferior, thus failing to meet the usage requirements. Comparative Example 2 is a commercially available reflective heat-insulating coating. Although it has been specifically optimized for reflective performance, effectively improving the coating's solar reflectance, the overall reflectance level is still lower than the examples. Furthermore, it has not been optimized in terms of self-cleaning and aging resistance, resulting in poor performance.

[0102] Comparative Example 3 is a reflective heat-insulating coating that uses only fluorocarbon resin. It has a high solar reflectance, reaching over 0.8. Due to the low surface energy of the fluorocarbon coating itself, its stain resistance is higher than that of conventional coatings. However, due to the lack of microstructure on the surface, the diffuse reflection and hydrophobic effects are insufficient, making it difficult to achieve a higher reflectance. The solar reflectance decreases significantly after contamination. Furthermore, due to the relatively weak adhesion between the coating and the filler and substrate, the coating's durability is relatively weaker than that of the example. After UV aging, it undergoes some discoloration, and the rate of change in solar reflectance is also relatively large.

[0103] Comparative Example 4 is a reflective heat-insulating coating modified with hydroxyl silicone oil. Its polysiloxane segments are distributed on the main chain rather than hanging from the side chains. Therefore, compared to the examples, the separation effect of its surface microphase structure is not significant. The doping of both actually reduces the coating's performance in terms of adhesion and durability. Furthermore, due to the absence of catechol groups, its matrix density and adhesion to the substrate are lower than those of the examples. Comparative Example 5 is a reflective heat-insulating coating prepared using acrylamide-grafted silicone resin. Because it also has hanging grafted polysiloxane side chains, it can form a certain degree of microphase separation on the surface. Therefore, it has a certain improvement in solar reflectance and durability. However, due to the absence of catechol groups, its matrix density and adhesion to the substrate are lower than those of the examples, making it difficult to completely fix the microphase structure. Therefore, the solar reflectance retention rate under long-term service and contamination conditions is still significantly different from that of the examples. Comparative Example 6 is a reflective heat-insulating coating prepared by grafting dopamine onto non-silicone resin. Since its overhanging grafted structure does not contain polysiloxane side chains but only catechol structures, the adhesion and durability of the coating are enhanced. However, due to the lack of microphase separation, the coating's solar reflectance, stain resistance, and changes in solar reflectance after aging are insufficient.

[0104] Comparative Example 7, prepared with a higher dosage of a special grafted modified silicone resin, exhibited a reflective heat-insulating coating. Due to the similar content of silicone and fluorocarbon resins, neither resin could form a good continuous phase during curing, resulting in poor coating integrity, weak adhesion, poor stain resistance, insufficient durability, and a significant performance degradation. Comparative Example 8, using an excessive amount of curing agent, resulted in a reaction between the excess isocyanate and the phenolic hydroxyl groups in the catechol, preventing the catechol groups from functioning properly. Consequently, the coating showed a significant difference in self-cleaning performance and durability compared to the examples.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly durable, self-cleaning, reflective, and heat-insulating coating, characterized in that: It consists of component A (main agent) and component B (curing agent). Component A (main agent) is prepared by mixing fluorocarbon resin, special grafted modified silicone resin, high-reflectivity filler, heat-insulating filler, solvent, and functional additives. Component B (curing agent) is prepared by isocyanate and solvent. The structural formula of the special grafted modified silicone resin is shown in the figure below. ； In the formula, n = 20~60; the mass ratio of the special grafted modified silicone resin to the fluorocarbon resin is 1: (5~10); the mass ratio of the A component resin to the B component curing agent is 1: (0.08~0.15).

2. The high-durability self-cleaning reflective heat-insulating coating according to claim 1, characterized in that... In the main component A, the contents of fluorocarbon resin, special grafted modified silicone resin, high reflectivity filler, heat insulation filler, solvent, and functional additives are 45%~55%, 5%~10%, 14%~20%, 10%~16%, 5%~15%, and 2%~4%, respectively, based on the total mass of component A; the fluorocarbon resin is at least one of solvent-based polyvinylidene fluoride resin, polychlorotrifluoroethylene-vinyl ether resin, and polychlorotetrafluoroethylene-vinyl ether resin; the high reflectivity filler is at least one of rutile titanium dioxide, potassium hexatitanate whiskers, and far-infrared ceramic powder; the heat insulation filler is at least one of hollow glass microspheres, ceramic hollow microspheres, and silica aerogel; the solvent is at least one of xylene, acetone, n-butanol, butyl acetate, dimethylformamide, and cyclic ether; and the functional additives are at least one of dispersant, defoamer, leveling agent, rheology modifier, ultraviolet absorber, and antioxidant.

3. The high-durability self-cleaning reflective heat-insulating coating according to claim 1, characterized in that... In the curing agent of component B, the content of isocyanate and solvent is 85%~100% and 0~15% respectively, based on the total mass of component B; wherein the isocyanate is at least one selected from toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, terephthalic diisocyanate, phenyl diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, and hexamethylene diisocyanate biuret; wherein the solvent is at least one selected from xylene, acetone, n-butanol, butyl acetate, dimethylformamide, and cyclic ether.

4. The high-durability self-cleaning reflective heat-insulating coating according to claim 1, characterized in that... The preparation method of the special grafted modified silicone resin includes the following steps: (1) Dissolve an appropriate amount of DL-homocysteine ​​thiolactone hydrochloride and sodium bicarbonate in an ethanol / water (1:1) mixed solvent. Add acryloyl chloride dropwise to the solution under low temperature conditions. The molar ratio of acryloyl chloride, DL-homocysteine ​​thiolactone hydrochloride and sodium bicarbonate is 1.05:1:2.

2. After the addition is completed, react at room temperature for 2 hours. Dilute the reaction solution with saturated brine and extract with ethyl acetate. Dry the extract by rotary evaporation to obtain acrylamide thiolactone (AMA). (2) Dissolve an appropriate amount of acrylamide thiolactone in 1,4-dioxane, add 3-mercapto-1-propanol and triethylamine to the solution, and react at room temperature for 8 h to obtain the addition product AMA-OH. Then add bis(3-aminopropyl)-terminated polydimethylsiloxane to the reaction solution and react at room temperature for 5 h to obtain the ring-opening product AMA-P of amino group and thiolactone. The molar ratio of acrylamide thiolactone, 3-mercapto-1-propanol and bis(3-aminopropyl)-terminated polydimethylsiloxane is 1:1:1, and the concentration of triethylamine is 5%. (3) N,N'-methylenebisacrylamide was added to AMA-P solution, wherein the molar ratio of AMA-P to N,N'-methylenebisacrylamide was 2:

1. The reaction was carried out at room temperature for 3 hours to obtain the coupling product DAMA-P. Dopamine methacrylamide was then added and the reaction was carried out at 50°C for 12 hours to obtain the addition product DAMA-P-DOPA solution, wherein the molar ratio of DAMA-P to dopamine methacrylamide was 1:4.

2. The solvent was removed by rotary evaporation of DAMA-P-DOPA solution to obtain the special grafted modified silicone resin.

5. The method for preparing a high-durability self-cleaning reflective heat-insulating coating according to claim 1, characterized in that... The preparation method of component A (main agent) and component B (curing agent) includes the following steps: (1) Preparation of component A: Weigh appropriate mass of each component, add fluorocarbon resin, special grafted modified silicone resin, high reflectivity filler and functional additives to a high-speed disperser in sequence, disperse the mixture at high speed for 30 min to 40 min until the system is uniform; add the mixture to a sand mill and grind for 2 h to 3 h, then add the ground mixture to a dispersion kettle and stir. During the stirring process, gradually add solvent and high heat insulation filler to the mixture. After the addition is completed, disperse for another 30 min until the system is uniform and stable to obtain component A of the coating. (2) Preparation of component B curing agent: The curing agent and solvent are dispersed and mixed for 30 min to 40 min until the system is homogeneous and stable to obtain the component B curing agent of the coating.

6. A method for preparing a high-durability self-cleaning reflective heat-insulating coating according to claim 5, characterized in that... The dispersion conditions in the high-speed disperser are a temperature of 40 ℃~60 ℃ and a linear velocity of 6 m / s~10 m / s; the grinding conditions in the ball mill are a linear velocity of 6 m / s~10 m / s and a grinding bead content of 75%~80%; the dispersion conditions in the dispersion kettle are a room temperature environment and a linear velocity of 2 m / s~3 m / s.

7. A high-durability self-cleaning reflective heat-insulating coating according to claim 1, characterized in that... The main component (A) and the curing agent (B) need to be mixed evenly according to the specified formula before application. The dry film thickness of the reflective heat insulation coating after application is 120 μm to 200 μm. The application method can be any one of spraying, roller coating, or brushing.

8. The application of the high-durability self-cleaning reflective heat-insulating coating as described in claim 1 in a vacuum environment as a surface protection material and temperature control material for building structures such as houses, buildings, factories, cold storage, industrial storage tanks, transportation infrastructure, and small components.

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