A self-healing anti-corrosion and cooling coating and its preparation method

Abstract

This invention discloses a self-healing, anti-corrosion, and cooling coating and its preparation method. The preparation method includes: TiO2 surface activation treatment; in-situ construction of a mesoporous silica shell and loading of a corrosion inhibitor; surface silane modification; and coating and curing after blending the obtained filler with resin and curing agent. The coating consists of a polymer resin matrix and a multifunctional core-shell nanocomposite material uniformly dispersed therein; the composite material has a three-level structure of core-shell-interface layer: titanium dioxide as the core, mesoporous silica loaded with corrosion inhibitor as the functional shell, and a silane coupling agent as the interfacial compatibility layer. Through multi-level structural design, this invention enables a single filler to simultaneously achieve high solar reflectance, high infrared emission, and intelligent release of corrosion inhibitors. The coating combines a physical barrier, active corrosion prevention, and radiation cooling triple protection mechanism, and can be widely used for long-term protection of outdoor metal or non-metal substrates.

Description

Technical Field

[0001] This invention relates to the field of functional coatings and composite materials, specifically to a self-healing, anti-corrosion, and cooling coating and its preparation method. This multifunctional composite coating achieves high compatibility with polymer resins through the core-shell structure design of the filler and surface engineering, while simultaneously endowing the coating with anti-corrosion and radiative cooling functions. It can be widely used for the protection of metal or non-metal surfaces such as outdoor energy storage facilities, offshore platforms, and building exteriors. Background Technology

[0002] Outdoor infrastructure (such as communication base stations, oil storage tanks, and bridge steel structures) is exposed to harsh natural environments for extended periods, facing the combined effects of strong ultraviolet radiation, high temperatures, high humidity, and salt spray corrosion. Prolonged high temperatures on the surface of these facilities significantly increase energy consumption and maintenance costs, while material aging and corrosion also seriously threaten their structural safety and service life. The corrosion rate of metals is closely related to ambient temperature, humidity, and pollutant concentration; high temperatures also greatly accelerate the electrochemical corrosion process.

[0003] Daytime radiative cooling technology utilizes materials with high reflectivity (>90%) in the solar spectrum (0.25-2.5 µm) and high infrared emissivity (>90%) in the "atmospheric window" band (8-13 µm) to continuously radiate heat into outer space, achieving energy-free cooling. Titanium dioxide (TiO2) is widely used in radiative cooling coatings due to its high refractive index (≈2.7) and good chemical stability in the visible light region. However, the direct application of TiO2 in protective coatings has significant drawbacks: nano-TiO2 particles have high surface energy and are prone to agglomeration in organic resin matrices, which not only impairs the uniformity and mechanical properties of the coating but also forms channels for corrosive media to penetrate, severely affecting its protective efficacy; TiO2 fillers lack active protection capabilities for metal substrates, and corrosion will occur rapidly once microcracks or defects appear in the coating; the introduction of traditional anti-corrosion fillers (such as zinc powder and phosphates) usually severely weakens the solar reflectivity of the coating, causing the radiative cooling function to fail.

[0004] In the existing technology, the research on combining radiation cooling and anti-corrosion functions is still in its early stages, and most of them adopt simple physical blending strategies. These strategies generally face core challenges such as poor functional synergy, insufficient long-term durability, and weak bonding between filler and resin interfaces. Specifically, the limitations of the existing technology mainly include: (1) poor compatibility between functional fillers and resin matrix, resulting in defects in the coating and accelerated aging; (2) lack of intelligent response and self-repair capability to coating damage; (3) difficulty in achieving excellent barrier protection and active electrochemical protection while ensuring high solar reflectivity and high infrared emissivity. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a self-healing anti-corrosion and cooling coating and its preparation method. This invention proposes a multi-functional integrated design by constructing a three-level structure of "core-functional shell-compatibility layer." It uses titanium dioxide as the optical core, mesoporous silica loaded with corrosion inhibitors as the multi-functional shell, and organosilane as the interface compatibility layer, all uniformly dispersed in a high-performance resin. This results in an integrated intelligent protective coating that combines excellent radiative cooling and long-term anti-corrosion performance. This coating not only provides a continuous cooling effect to the substrate, reducing corrosion kinetics, but also releases corrosion inhibitors when damaged, achieving a multi-functional synergistic effect. This solves key technical problems in traditional functional coatings, such as poor filler dispersibility and the mutual constraint between protective and cooling functions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention first provides a method for preparing a composite coating that combines radiation cooling and self-healing corrosion protection functions, the method comprising the following steps:

[0008] 1) Activate TiO2 nanopowder to obtain activated TiO2 powder with hydroxyl groups on the surface;

[0009] 2) Activated TiO2 powder was dispersed in a mixed solution of alcohol, water and ammonia, and template agent and corrosion inhibitor were added and stirred. An alcohol solution of organosilicon source was slowly added dropwise, and the organosilicon source was hydrolyzed and condensed under stirring conditions to form a mesoporous silica shell loaded with corrosion inhibitor in situ on the TiO2 surface. After the reaction was completed, a core-shell structure product was obtained. The product was subjected to solid-liquid separation, washing, and template agent was removed by solvent extraction. After drying, TiO2@mSiO2 intermediate was obtained.

[0010] 3) The intermediate obtained in step 2) is dispersed in an alcoholic solution of silane coupling agent, the pH is adjusted to 4-6, and the reaction is heated to form a silane compatibility layer on the surface. The product is centrifuged, washed to remove the physically adsorbed silane coupling agent, and dried to obtain a multifunctional core-shell nanocomposite material.

[0011] 4) The multifunctional core-shell nanocomposite material is blended with polymer resin base material and curing agent to obtain a composite coating. The coating is applied to the surface of the substrate and cured to form a composite coating with both radiation cooling and self-healing anti-corrosion functions.

[0012] According to a preferred embodiment of the present invention, in step 1), the TiO2 nanopowder is preferably of rutile crystal form, with an average particle size of 20~100 nm, preferably 50 nm.

[0013] According to a preferred embodiment of the present invention, in step 1), hydroxyl groups can be introduced into the surface of TiO2 nanopowder by etching with a strong oxidizing agent or acid-base treatment to obtain activated TiO2 powder with a surface rich in hydroxyl groups. Preferably, TiO2 nanopowder is dispersed in nitric acid solution, and then subjected to ultrasonication, heating and reflux, centrifugation and washing, and drying to obtain activated TiO2 powder with a surface rich in hydroxyl groups.

[0014] According to a preferred embodiment of the present invention, in step 2), activated TiO2 powder is dispersed in a mixed solution composed of alcohol, deionized water, and concentrated ammonia at a solid-liquid ratio of 1:50 to 1:80 g / mL, and ultrasonically dispersed to form a uniform slurry. Preferably, the mass ratio of alcohol, water, and concentrated ammonia in the mixed solution is (100~1000):(20~30):(1~1.5), wherein the mass percentage concentration of concentrated ammonia is 28 wt%.

[0015] According to a preferred embodiment of the present invention, the alcohols in the mixed solution of step 2), the alcohol solution of the organosilicon source, and the alcohol solution of the silane coupling agent in step 3) are C1–C4 alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Preferably, the alcohols in the mixed solution, the alcohol solution of the organosilicon source, and the alcohol solution of the silane coupling agent are the same alcohol.

[0016] According to a preferred embodiment of the present invention, in step 2), the template agent is at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and sodium dodecyl sulfonate, and the amount of template agent used is 20% to 60% of the mass of TiO2.

[0017] According to a preferred embodiment of the present invention, in step 2), the corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, sodium molybdate, and zinc phosphate, and the amount of corrosion inhibitor is 1% to 5% of the mass of ethanol in the mixed solution.

[0018] According to a preferred embodiment of the present invention, in step 2), the amount of organosilicon source in the alcohol solution is 10% to 30% of the alcohol mass. The organosilicon source is one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and dimethyldimethoxysilane.

[0019] Preferably, the dropping rate of the organosilicon-derived alcohol solution is 0.5~2 mL / min.

[0020] According to a preferred embodiment of the present invention, the temperature of the hydrolysis-condensation reaction in step 2) is 30~60℃.

[0021] According to a preferred embodiment of the present invention, in step 2), the template agent is removed by solvent extraction, which includes: redispersing the washed product in an acidic ethanol solution and gently stirring at 20~60°C to extract and remove the silane coupling agent.

[0022] According to a preferred embodiment of the present invention, in step 3), the silane coupling agent is selected from at least one of the following: KH550, KH560, KH570, and the mass percentage concentration of the silane coupling agent in the alcohol solution is 1% to 5%.

[0023] According to a preferred embodiment of the present invention, in step 3), the intermediate is dispersed in an alcoholic solution of silane coupling agent at a solid-liquid ratio of 1:50 to 1:80 g / mL.

[0024] According to a preferred embodiment of the present invention, the temperature of the heating reaction in step 3) is 50~70°C, and the reaction time is 6~8h.

[0025] According to a preferred embodiment of the present invention, in step 4), the mass ratio of the multifunctional core-shell nanocomposite material, polymer resin base material, and curing agent is (5~30): (50~100): (3~5).

[0026] Preferably, the polymer resin base material, by weight, comprises: 60-80 parts polysiloxane resin, 20-25 parts xylene, 15-25 parts butyl acetate, 0.1-0.6 parts defoamer, and 0.2-1.5 parts leveling agent. The curing agent comprises: 90-98 parts aminosilane resin and 2-10 parts xylene.

[0027] According to a preferred embodiment of the present invention, in step 4), the composite coating is applied to the surface of the substrate to obtain a liquid coating film, the thickness of the liquid coating film is controlled between 100 and 200 μm, and then it is placed in an oven at 120 to 150°C for curing treatment for 1 to 2 hours, thereby forming a functional composite coating with a dry film thickness between 50 and 100 μm.

[0028] This invention also provides a multifunctional composite coating with both radiative cooling and self-healing corrosion protection functions, obtained by the aforementioned method. The coating consists of a polymer resin matrix and the aforementioned multifunctional core-shell nanocomposite material uniformly dispersed therein. The polymer resin is preferably an organosilicon resin or an epoxy resin, and the amount of the multifunctional core-shell nanocomposite material can be adjusted within a specific range according to performance requirements. This coating system not only exhibits excellent daytime radiative cooling capacity, manifested in high solar reflectivity and atmospheric window infrared emissivity, but also possesses excellent corrosion protection performance. It can provide long-term protection for the substrate through the synergistic effect of physical barriers and chemical corrosion inhibition, and exhibits active protection characteristics by intelligently releasing corrosion inhibitors when the coating is damaged.

[0029] Experiments have shown that controlling the thickness of the mesoporous silica shell is a key factor in optimizing the optical performance of multilayer nanofillers. Excessively thick SiO2 coatings reduce the scattering efficiency of TiO2 nanoparticles in the visible light region, which is not conducive to leveraging the high refractive index advantage of TiO2. On the other hand, the core-shell size optical optimization design can not only maintain the high scattering ability of the TiO2 core, but also further enhance the overall solar reflectivity of the coating through refractive index engineering and compensation for ultraviolet absorption, while endowing it with chemical stability, compatibility and high infrared emission characteristics.

[0030] In-situ co-assembly and mild extraction techniques are key to successfully loading and maintaining the activity of corrosion inhibitors. Corrosion inhibitor molecules are introduced during the sol-gel process, embedding them into the growing silica network. Subsequent template removal using mild solvents such as acidic ethanol creates open channels without damaging the inhibitor structure, causing some of the inhibitor to be "locked" within these channels due to solubility changes. This method yields corrosion inhibitor loadings of 10–15 wt%, and the release behavior is correlated with local microenvironmental changes caused by coating damage or media penetration, exhibiting intelligent response characteristics.

[0031] Compared with existing technologies, the beneficial effects of this invention are mainly reflected in its innovative solution to the optical mismatch and interface failure problems between high-reflectivity fillers and resin matrices through the construction of a multi-level synergistic optical and protective structure of "core-functional shell-interface layer," while simultaneously achieving an essential fusion of spectral selectivity modulation and long-term corrosion protection. The specific advantages of this coating system are as follows:

[0032] (1) Through the in-situ construction of the mesoporous silica shell and the design of the corrosion inhibitor loading, a single type of filler (TiO2 nanofiller) simultaneously achieves high solar light reflection, high infrared thermal radiation and chemical corrosion inhibition functions, breaking through the performance bottleneck caused by the superposition of functions of traditional coatings; (2) The silane compatibility layer on the surface forms a strong chemical bond with the resin matrix, significantly improving the interfacial bonding strength and the excellent dispersion stability of the filler, effectively preventing early failure of the coating caused by filler agglomeration or interfacial defects; (3) The coating has a triple protection mechanism of "physical barrier + chemical slow release + photothermal management": the dense coating and strong interfacial bonding provide a passive barrier, the corrosion inhibitor loaded in the pores can intelligently release in response to damage to provide active protection, and the high reflectivity and high emission characteristics of the filler itself continuously reduce the substrate temperature and corrosion kinetic rate. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a multifunctional protective coating. Detailed Implementation

[0034] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0035] This invention provides a method for preparing a composite coating that combines radiation cooling and self-healing corrosion protection functions. Typically, but not limited to, the method can be implemented according to the following process:

[0036] (1) Surface pretreatment of TiO2: TiO2 nanoparticles were dispersed in a 1-3 mol / L nitric acid solution at a solid-liquid ratio of 1:20~1:40 (g / mL) and ultrasonically treated for 10-30 min. The mixture was then refluxed in an oil bath at 60-80°C with stirring for 6 h. After the reaction, the resulting product was centrifuged and washed sequentially to remove excess nitric acid. The washed solid product was placed in a forced-air drying oven and vacuum dried at 60-80°C for 2-6 h to obtain activated titanium dioxide powder with hydroxyl-rich surface.

[0037] In step (1), the preferred power for ultrasonic treatment is 50 W to 300 W. The centrifugation rate is 6000 to 10000 rpm, and the time is 5 to 15 min.

[0038] (2) In-situ construction of mesoporous silica functional shell and loading of corrosion inhibitor: The activated titanium dioxide powder was dispersed in a mixed solution of anhydrous ethanol, deionized water and concentrated ammonia at a solid-liquid ratio of 1:50~1:80 (g / mL) and ultrasonically dispersed for 30 minutes at a power of 300~600 W to form a uniform slurry. Then, a template agent and a corrosion inhibitor were added to the slurry and stirred in a water bath at 30~60℃ for 1~3 h to allow the corrosion inhibitor to fully dissolve and partially enter the hydrophobic region of the micelles, resulting in mixture A. Anhydrous ethanol and tetraethyl orthosilicate (TEOS) were stirred and mixed at room temperature for 10~30 min to obtain solution B. Under continuous stirring, solution B was slowly added dropwise to the above mixture A at a rate of 0.5~2 mL / min using a constant flow pump. TEOS hydrolyzed and co-assembled on the template agent micelles and TiO2 surface to form a primary core-shell structure. After the addition was complete, the reaction was continued at a constant temperature of 30-60℃ for 24 hours to allow the SiO2 network to fully cross-link and solidify, completing the initial encapsulation of the corrosion inhibitor. After the reaction, the product was collected by centrifugation, and the washed product was redispersed in an acidic ethanol solution (prepared from 95 mL of anhydrous ethanol and 5 mL of concentrated hydrochloric acid). The solution was gently stirred at 60℃ for 6 hours to extract and remove the surfactant template. After centrifugation, washing, and drying again, the TiO2@mSiO2 (corrosion inhibitor) intermediate was obtained.

[0039] In step (2), the mass ratio of anhydrous ethanol, deionized water, and concentrated ammonia (28 wt%) in the mixed solution is 100:30:1.5.

[0040] (3) Intermediate surface compatibility modification: The intermediate product obtained in step (2) was dispersed in a 1% to 3% silane coupling agent / ethanol solution at a solid-liquid ratio of 1:50 to 1:80 (g / mL). Glacial acetic acid was added to adjust the pH to 4 to 6, and the reaction was carried out at 50 to 70 °C for 6 to 8 h. After the reaction was completed, the product was centrifuged and washed to remove the physically adsorbed silane. The final product was dried in a vacuum drying oven at 60 to 80 °C for 6 to 8 h to obtain the target multifunctional core-shell nanocomposite material, denoted as F-TiO2.

[0041] (4) Preparation and application of multifunctional protective coating: Functionalized fillers and polysiloxane resin base were blended and continuously mixed at a mechanical stirring rate of 800-1600 rpm for 20-60 min. Then, a curing agent was introduced into the system, and the reaction was continued at a stirring speed of 700-1300 rpm for 15-30 min at room temperature, finally obtaining a multifunctional composite coating with multiple protective properties. This composite coating was applied to a pre-treated metal substrate, controlling the liquid film thickness between 100-200 μm, and then cured in an oven at 120-150℃ for 1-2 h, thus forming a dense composite multifunctional protective coating with a dry film thickness between 50-100 μm. Figure 1 This is a schematic diagram of the structure of a multifunctional protective coating.

[0042] The present invention will be further described and illustrated below with reference to several specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0043] Example 1:

[0044] 5.0 g of rutile titanium dioxide powder with an average particle size of 50 nm was weighed and added to 150 mL of 2 mol / L nitric acid solution (solid-liquid ratio 1:30 g / mL). The mixture was ultrasonically dispersed at 400 W for 20 min. The flask was placed in an oil bath at 75 °C and mechanically stirred and refluxed at 300 rpm for 6 h. After the reaction was completed, the mixture was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min. The supernatant was discarded. The supernatant was repeatedly washed with deionized water until the pH of the supernatant was 7, and then washed twice with anhydrous ethanol. The resulting solid was dried in a vacuum drying oven at 80 °C for 4 h to obtain activated titanium dioxide powder with a surface rich in hydroxyl groups.

[0045] Weigh 2.0 g of activated TiO2 powder and disperse it in a mixed solution consisting of 100 mL anhydrous ethanol, 30 mL deionized water, and 1.5 mL concentrated ammonia (28 wt%). Disperse the mixture ultrasonically (400 W) for 30 min to form a homogeneous slurry. Add 0.8 g of hexadecyltrimethylammonium bromide (CTAB) and 0.3 g of benzotriazole (BTA) to this slurry and stir at 300 rpm for 2 h in a 45°C water bath to obtain mixture A. Separately, mix 2.5 mL of tetraethyl orthosilicate (TEOS) with 20 mL of anhydrous ethanol and stir magnetically for 10 min to obtain solution B. Slowly add solution B to mixture A at a rate of 1 mL / min using a constant flow pump, maintaining a constant temperature of 45°C and stirring at 300 rpm throughout the addition process. After the addition is complete, continue the reaction at 45°C for 24 h. After the reaction is complete, collect the product by centrifugation and wash once with anhydrous ethanol. The product was redispersed in 100 mL of acidic ethanol solution (prepared from 95 mL of anhydrous ethanol and 5 mL of concentrated hydrochloric acid) and gently stirred at 60 °C for 6 h to extract the template. After centrifugation again, the product was washed twice with an ethanol / water (1:1) mixture and finally dried under vacuum at 60 °C for 8 h to obtain the intermediate product TiO2@mSiO2(BTA).

[0046] 2.0 g of TiO2@mSiO2(BTA) was weighed and dispersed in 80 mL of 2% (w / w) KH-550 ethanol solution. 0.2 mL of glacial acetic acid was added, and the pH of the system was adjusted to 5.0 using a pH meter. The reaction was carried out in an oil bath at 65℃ for 7 h with magnetic stirring at 250 rpm. After the reaction was complete, the solid was collected by centrifugation and washed three times with anhydrous ethanol. The final product was dried in a vacuum drying oven at 70℃ for 7 h to obtain the target multifunctional core-shell nanocomposite material, denoted as F-TiO2.

[0047] Base material formulation: 60.0 g polysiloxane resin, 22.0 g xylene, 18.0 g butyl acetate, 0.4 g silicone defoamer, 0.8 g polyether modified leveling agent. Curing agent formulation: 12.0 g aminosilane resin, 1.0 g xylene.

[0048] Add each component of the base material to a beaker sequentially and stir at low speed until homogeneous. Add 15.0 g of F-TiO2 filler, first stir at 1500 rpm for 30 minutes using a high-speed disperser, then treat with an ultrasonic cell disruptor (400 W) for 20 minutes to obtain a homogeneous slurry. Add the curing agent and stir at 1000 rpm for 20 minutes. Vacuum degas the resulting coating for 15 minutes. Apply the coating to a sandblasted Q235 carbon steel plate (100 mm × 50 mm × 2 mm), controlling the wet film thickness to 150 μm. Place the sample in an oven and cure according to the following procedure: 80℃ / 40 min → 120℃ / 90 min → 150℃ / 30 min. Finally, a composite coating with a dry film thickness of 80 ± 5 μm is obtained.

[0049] Performance Testing: The average solar reflectance of the coating was measured to be 0.93 using a UV-Vis-NIR spectrophotometer (with integrating sphere). The average emissivity was measured to be 0.95 using a Fourier transform infrared spectrometer. The coated sample was immersed in a 3.5 wt% NaCl solution. After 30 days, the low-frequency impedance modulus (|Z| 0.1 Hz) was measured to be 8.5 × 10⁻⁶. 9 Ω·cm 2 According to GB / T 1771-2007, a 1000-hour neutral salt spray test was conducted. The corrosion spread width at the scratched area was <1 mm, and there was no blistering or rust in the unscratched area. According to GB / T 9286-1998, the adhesion was grade 0 (cross-cut test). Compared to the outdoor environment, the coating's outdoor temperature drop can reach 8.4℃.

[0050] Example 2 (low filler content):

[0051] The preparation method of the filler F-TiO2 is the same as in Example 1. The formulations of the base material and curing agent are the same as in Example 1. 10.0 g of F-TiO2 filler is added. The dispersion and curing processes are the same as in Example 1.

[0052] Performance testing: Solar reflectance 0.86, mid-infrared emissivity 0.89; low-frequency impedance after 30 days of immersion is 5.2 × 10⁻⁶. 9 Ω·cm 2 The coating exhibits improved flexibility and flowability, but with a slight decrease in optical properties and performance. A 1000-hour neutral salt spray test according to GB / T 1771-2007 showed corrosion spread width of <1 mm at the scratched area, and no blistering or rust in the unscratched area. Adhesion was rated at grade 0 (cross-cut test) according to GB / T 9286-1998. Compared to outdoor environments, the coating resulted in a 4.1℃ temperature drop.

[0053] Example 3 (High filler content):

[0054] The preparation method of the filler F-TiO2 is the same as in Example 1. The formulations of the base material and curing agent are the same as in Example 1. 20.0 g of F-TiO2 filler is added. Due to the high filler content, the high-speed dispersion time needs to be extended to 45 min, and the ultrasonic treatment needs to be increased to 30 min. The curing process is the same as in Example 1.

[0055] Performance testing: Solar reflectance 0.91, mid-infrared emissivity 0.96; low-frequency impedance after 30 days of immersion is 1.1 × 10⁻⁶. 10 Ω·cm 2 A 1000-hour neutral salt spray test was conducted according to GB / T 1771-2007. The corrosion spread width at the scratched area was <1 mm, and there was no blistering or rust in the unscratched area. According to GB / T 9286-1998, the adhesion was grade 0 (cross-cut test). Compared to the outdoor environment, the coating experienced a temperature drop of 8.5℃ outdoors.

[0056] Example 4 (Sodium molybdate supported):

[0057] The filler preparation steps were basically the same as in Example 1, except that the corrosion inhibitor was replaced with 1.0 g of sodium molybdate (Na2MoO4) instead of 0.6 g BTA. Since sodium molybdate is water-soluble, it was directly dissolved in the deionized water component in step 2, and then mixed with ethanol and ammonia. Other parameters remained unchanged, resulting in a core-shell filler with sodium molybdate as the corrosion inhibitor, denoted as F-TiO2-Mo. Coating preparation: The same silicone resin formulation, filler content (15.0 g), and process as in Example 1 were used.

[0058] Performance testing: Solar reflectance 0.85, emissivity 0.90; low-frequency impedance after 30 days of immersion is 3.4 × 10⁻⁶. 9 Ω·cm 2 According to GB / T 1771-2007, a 1000-hour neutral salt spray test was conducted, and the corrosion spread width at the scratch was >2 mm. According to GB / T9286-1998, the adhesion was grade 0 (cross-cut test). Compared to the outdoor environment, the coating experienced a 4.3℃ temperature drop outdoors.

[0059] Comparative Example 1 (Physical Blending):

[0060] The formulation and process are the same as in Example 1, but 15.0 g F-TiO2 is replaced with a simple physical mixture of 12.0 g unmodified TiO2 powder and 3.0 g BTA powder.

[0061] Performance testing: Solar reflectance 0.86, emissivity 0.82; low-frequency impedance after 30 days of immersion is 1.5 × 10⁻⁶. 7 Ω·cm 2According to GB / T 1771-2007, a 1000-hour neutral salt spray test was conducted, and the corrosion spread width at the scratch was >5 mm. According to GB / T9286-1998, the adhesion was grade 2 (cross-cut test). Compared to the outdoor environment, the coating experienced a 2.5℃ temperature drop outdoors.

[0062] Comparative Example 2 (core-shell filler coating without corrosion inhibitor):

[0063] The preparation method is the same as in Example 1, but benzotriazole (BTA) is not added in step 2 to obtain TiO2@mSiO2 filler, and organosilicon coating is prepared accordingly.

[0064] Performance testing: Solar reflectance 0.92, emissivity 0.90; low-frequency impedance after 30 days of immersion is 6.0 × 10⁻⁶. 8 Ω·cm 2 According to GB / T 1771-2007, a 1000-hour neutral salt spray test was conducted, and the corrosion spread width at the scratch was >4 mm. According to GB / T9286-1998, the adhesion was rated as Grade 1 (cross-cut test). Compared to the outdoor environment, the coating experienced an outdoor temperature drop of 8.1℃.

[0065] Table 1 Comparison of test results between Examples 1-4 and Comparative Examples 1-2

[0066]

[0067] According to actual experimental data, the multifunctional core-shell nanocomposite materials and their organosilicon coatings prepared in the various embodiments of this invention exhibit comprehensive and significant advantages in terms of radiative cooling performance, long-term corrosion resistance, and overall adhesion. Specifically, all coatings in the embodiments demonstrate excellent overall performance balance: the highest solar reflectivity reaches 0.93, the highest infrared emissivity reaches 0.96, and the corresponding maximum outdoor temperature drop exceeds 8.4℃; in terms of corrosion resistance, the low-frequency impedance modulus of the coatings in the embodiments remains stable at 10. 9 Ω·cm 2 Order of magnitude, reaching a maximum of 1.1 × 10⁻⁶. 10 Ω·cm 2 Furthermore, the adhesion strength reached the highest level, Grade 0. These data fully demonstrate that the multi-level structure of "core-functional shell-compatibility layer" constructed by this invention can simultaneously achieve efficient spectral modulation, a strong medium barrier and active corrosion inhibition protection, and a robust interfacial bond.

[0068] The comparative results, from the opposite perspective, confirm the necessity of the core design of this invention. The various properties of Comparative Example 1 (simple physical blend), especially the corrosion resistance (1.5 × 10⁻⁶), are significantly improved. 7The corrosion resistance (Ω·cm) decreased by an order of magnitude, and the adhesion deteriorated, clearly indicating that the lack of a core-shell structure and in-situ encapsulation would prevent the functional components from working synergistically, resulting in severely compromised performance. Comparative Example 2 (without corrosion inhibitor) retained better optical properties, but its corrosion resistance (6.0 × 10⁻⁶) decreased significantly. 7 Ω·cm 2 The significantly lower loading rate compared to all other embodiments clearly demonstrates the crucial role of corrosion inhibitor loading in providing active protection and maintaining the long-term durability of the coating. These comparisons clearly show that the in-situ loading technology of the mesoporous silica shell and the surface silanization modification process employed in this invention are an indispensable technical path to achieve multifunctional integration and long-term stable performance of the coating.

[0069] In summary, the experimental results fully verify the effectiveness and innovation of the technical solution of this invention, successfully achieving deep synergy between radiation cooling and long-term corrosion protection in a single coating, and achieving the intended purpose of the invention.

[0070] The above embodiments of the present invention are illustrative and not limiting. Any changes within the meaning and scope of the claims should be considered to be included within the scope of the claims.

[0071] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a self-healing, anti-corrosion, and cooling coating, characterized in that, Includes the following steps: 1) Activate TiO2 nanopowder to obtain activated TiO2 powder with hydroxyl groups on the surface; 2) Activated TiO2 powder was dispersed in a mixed solution of alcohol, water and ammonia, and template agent and corrosion inhibitor were added and stirred. An alcohol solution of organosilicon source was slowly added dropwise, and the organosilicon source was hydrolyzed and condensed under stirring conditions to form a mesoporous silica shell loaded with corrosion inhibitor in situ on the TiO2 surface. After the reaction was completed, a core-shell structure product was obtained. The product was subjected to solid-liquid separation, washing, and template agent was removed by solvent extraction. After drying, TiO2@mSiO2 intermediate was obtained. 3) The intermediate obtained in step 2) is dispersed in an alcoholic solution of silane coupling agent, the pH is adjusted to 4-6, and the reaction is heated to form a silane compatibility layer on the surface. The product is centrifuged, washed to remove the physically adsorbed silane coupling agent, and dried to obtain a multifunctional core-shell nanocomposite material. 4) The multifunctional core-shell nanocomposite material is blended with polymer resin base material and curing agent to obtain a composite coating, which is applied to the surface of the substrate and cured to form a composite coating with both radiation cooling and self-healing anti-corrosion functions.

2. The method according to claim 1, characterized in that, Step 1) The TiO2 nanopowder is rutile crystal form with an average particle size of 20~100 nm.

3. The method according to claim 1, characterized in that, In step 2), activated TiO2 powder is dispersed in the mixed solution at a solid-liquid ratio of 1:50~1:80 g / mL and ultrasonically dispersed to form a uniform slurry; the alcohols in the mixed solution, the alcohol solution of the organosilicon source, and the alcohol solution of the silane coupling agent in step 3) are C1–C4 alcohols.

4. The method according to claim 1, characterized in that, The template agent is at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and sodium dodecyl sulfonate, and the amount of template agent used is 20% to 60% of the mass of activated TiO2 powder; the corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, sodium molybdate, and zinc phosphate, and the amount of corrosion inhibitor used is 0.1% to 5% of the mass of ethanol in the mixed solution.

5. The method according to claim 1, characterized in that, In step 2), the amount of organosilicon source in the alcohol solution is 10% to 30% of the mass of alcohol; the organosilicon source is one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and dimethyldimethoxysilane.

6. The method according to claim 1, characterized in that, In step 3), the intermediate is dispersed in an alcoholic solution of silane coupling agent at a solid-liquid ratio of 1:50 to 1:80 g / mL; the mass percentage concentration of silane coupling agent in the alcoholic solution of silane coupling agent is 1% to 5%; the silane coupling agent is at least one of KH550, KH560, and KH570.

7. The method according to claim 1, characterized in that, Step 2) The temperature for the hydrolysis-condensation reaction is 30~60℃; Step 3) The temperature for the heating reaction is 50~70℃.

8. The method according to claim 1, characterized in that, In step 4), the mass ratio of the multifunctional core-shell nanocomposite material, polymer resin base material, and curing agent is (5~30): (50~100): (3~5).

9. The method according to claim 1, characterized in that, In step 4), the composite coating is applied to the surface of the substrate to obtain a liquid coating film. The thickness of the liquid coating film is controlled between 100 and 200 μm. Then, a curing treatment is performed to form a functional composite coating with a dry film thickness between 50 and 100 μm.

10. A multifunctional composite coating that combines radiative cooling and self-healing corrosion protection, characterized in that, It is prepared by the method described in any one of claims 1-9.

Images