Water-based anticorrosive paint with metal powder doped with porous particles and preparation method of water-based anticorrosive paint

Abstract

The invention relates to the technical field of anticorrosive coatings, and discloses a water-based anticorrosive coating with metal powder doped with porous particles and a preparation method thereof.The preparation method comprises the steps that porous silicon dioxide particles are subjected to surface modification treatment, and metal zinc powder is loaded to form core-shell structure composite particles; preparing and loading a composite microcapsule containing sodium alginate and a polypeptide derivative and a composite microcapsule containing calcium chloride and a cyclodextrine derivative in different pore regions of the porous silicon dioxide particles; and dispersing the prepared composite particles in water-borne epoxy resin to prepare the anticorrosive paint. According to the invention, the synergistic effect of a self-healing bionic mucus layer and a dual adhesion function is realized, the problem of sedimentation of metal zinc powder is solved, the coating is endowed with self-repairing capability, the adhesion strength of the repairing layer is enhanced, a three-stage protection structure is formed, and the long-term corrosion resistance of the coating in a severe environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion coatings, and more specifically, it relates to an aqueous anti-corrosion coating doped with metal powder and porous particles and a preparation method thereof. Background Art

[0002] With the increasingly strict environmental protection regulations, aqueous anti-corrosion coatings are gradually replacing solvent-based anti-corrosion coatings due to their environmental advantages of low VOC emissions. As a commonly used anti-corrosion pigment, metallic zinc powder can effectively prevent the corrosion of metal substrates through the principle of sacrificial anode protection. However, in the aqueous epoxy system, metallic zinc powder has the following three main technical problems: First, metallic zinc powder has a large density and is prone to sedimentation in the aqueous system, resulting in poor storage stability of the coating, short service life, and deteriorated construction performance. Existing technologies usually improve this problem by adding thickeners or dispersants, but this often affects the final performance of the coating.

[0003] Second, once the existing aqueous anti-corrosion coatings are mechanically damaged during use and the protective layer is broken, they cannot self-repair, and the corrosive medium will quickly penetrate to the surface of the substrate, accelerating the corrosion process. Although some existing self-healing technologies can achieve coating repair, the repair effect is limited.

[0004] Third, even for coatings using self-healing technologies, the bonding strength between the repair layer and the metal substrate is often insufficient, and the repair layer is prone to peeling off under conditions such as water flow scouring or mechanical friction, unable to provide durable and effective protection. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an aqueous anti-corrosion coating doped with metal powder and porous particles and a preparation method thereof.

[0006] An aqueous anti-corrosion coating doped with metal powder and porous particles, comprising: surface-modified porous silica particles loaded with metallic zinc powder, and the surface-modified porous silica particles and the metallic zinc powder form a core-shell structure composite particle; sodium alginate-polypeptide derivative composite microcapsules and calcium chloride-cyclodextrin derivative composite microcapsules loaded in the pores of the surface-modified porous silica particles, the sodium alginate-polypeptide derivative composite microcapsules are mainly distributed in the deep layer area of the pores, and the calcium chloride-cyclodextrin derivative composite microcapsules are mainly distributed in the surface layer area of the pores; and an aqueous epoxy resin, and the core-shell structure composite particles are uniformly dispersed in the aqueous epoxy resin.

[0007] Preferably: the polypeptide derivative is a mussel foot thread protein polypeptide derivative, and the polypeptide derivative and the cyclodextrin derivative can form a host-guest recognition effect.

[0008] Preferably: The surface-modified porous silica particles are obtained by surface-modifying the porous silica particles with a silane coupling agent to introduce functional groups that form a coordination interaction with metallic zinc powder.

[0009] Preferably: The silane coupling agent is γ-aminopropyltriethoxysilane, and the functional group is an amino group.

[0010] Preferably: The porous silica particles have an average particle size of 200 - 500 nm, a specific surface area of 400 - 800 m² / g, and a pore diameter of 5 - 20 nm.

[0011] Preferably: The cyclodextrin derivative is a β-cyclodextrin derivative modified with p-aminobenzoic acid.

[0012] 7. The waterborne anticorrosive coating of a metal powder-doped porous particle according to claim 1, wherein the solid content of the waterborne anticorrosive coating is 55 - 65 wt%, the pH value is 7.5 - 8.5, and the viscosity is 1500 - 2500 mPa·s.

[0013] A preparation method of a waterborne anticorrosive coating of a metal powder-doped porous particle, comprising the following steps: Step 1: Perform surface modification treatment on the porous silica particles; Step 2: Load metallic zinc powder on the surface of the surface-modified porous silica particles obtained in Step 1 to form core-shell structure composite particles; Step 3: Prepare sodium alginate-polypeptide derivative composite microcapsules and calcium chloride-cyclodextrin derivative composite microcapsules; Step 4: Load the two kinds of composite microcapsules obtained in Step 3 into different pore regions of the core-shell structure composite particles obtained in Step 2; Step 5: Disperse the core-shell structure composite particles loaded with composite microcapsules obtained in Step 4 in waterborne epoxy resin to obtain a waterborne anticorrosive coating.

[0014] Preferably: The method of surface modification in Step 1 is: Add the porous silica particles into an anhydrous toluene solution containing 3 - 5 wt% of γ-aminopropyltriethoxysilane, stir and react at 70 - 80 °C for 8 - 12 hours to cause the silane coupling agent to undergo a condensation reaction with the silanol groups on the silica surface, introducing amino functional groups.

[0015] Preferably: The method of loading metallic zinc powder in Step 2 is: Mix metallic zinc powder with a particle size of 1 - 3 μm and the surface-modified porous silica particles in a weight ratio of 1:1 - 3:1, add them into anhydrous ethanol containing 0.5 - 2 wt% of polyvinylpyrrolidone, ultrasonically disperse, and then carry out a solvothermal reaction at 120 - 150 °C for 6 - 8 hours Preferably, the method for loading the composite microcapsules in step 4 is as follows: First, immerse the core-shell structured composite particles in an ethanol solution containing sodium alginate-polypeptide derivative composite microcapsules, perform ultrasonic treatment, and then immerse for 2 hours under reduced pressure conditions. Then, immerse the obtained intermediate product in an ethanol solution containing calcium chloride-cyclodextrin derivative composite microcapsules and immerse for 1 hour under the same conditions.

[0016] Preferably, the method for preparing the coating in step 5 is as follows: Add the core-shell structured composite particles loaded with the composite microcapsules to the waterborne epoxy resin system at a weight percentage of 20-30% of the total solid content, stir and disperse under low shear force conditions, and then add a water-dispersible epoxy curing agent. The beneficial effects of the present invention are as follows: By surface modification of the porous silica microparticles and loading of metallic zinc powder by the solvothermal method, core-shell structured composite particles are formed, enabling the uniform dispersion of the metallic zinc powder in the waterborne epoxy system and solving the sedimentation problem of zinc powder coatings. Experimental tests show that after standing at room temperature for 30 days, the sedimentation rate of this coating is below 5%, while the sedimentation rate of general zinc powder coatings is 20-30%. The storage period of this coating reaches more than 6 months, exceeding the 3-month storage period of conventional waterborne zinc powder coatings.

[0017] Through the self-healing effect of the bionic mucus layer, a gel-like repair layer is formed on the coating after mechanical damage, filling the cracks and restoring the protective function. Self-healing efficiency tests show that the coating restores approximately 85% of its original barrier performance within 24 hours after scratch damage and can achieve multiple self-healings, with the number of repair times at a single position reaching 3-5 times. This exceeds the ability of existing self-healing coatings, which can usually only be repaired 1-2 times.

[0018] Through the dual adhesion effect, the bonding strength between the repair layer and the metal substrate is improved. Tensile adhesion tests show that the adhesion strength of the repaired coating reaches above 2.5 MPa, while the adhesion strength of the repair layer of existing self-healing coatings is usually 0.5-1.5 MPa. The repair layer shows anti-scouring performance in the 90° peel test and maintains integrity under the water flow scouring condition of 5 L / min, which is important for the protection of equipment exposed to harsh environments for a long time.

[0019] Through the synergistic effect of the sacrificial anode protection of metallic zinc powder, the physical barrier of the porous carrier, the repair effect of the self-healing gel, and the enhanced effect of the dual adhesion effect, this coating achieves comprehensive anti-corrosion protection. Salt spray tests show that after 500 hours of salt spray exposure (ASTM B117 standard), the corrosion spread distance of this coating is less than 1 mm, which is superior to general zinc powder coatings (usually 3-5 mm) and ordinary self-healing coatings (usually 2-3 mm).

[0020] This coating maintains good protective effects under conditions such as high humidity (95% RH), high salinity (3.5% NaCl), and temperature fluctuations (-20°C to 60°C). After the cyclic thermal shock test (-20°C and 60°C alternating, one cycle every 8 hours, for a total of 30 cycles), no cracking or peeling occurred on the coating, which is attributed to the buffering effect of the porous carrier and the gel-like repair layer on temperature stress.

[0021] Waterborne epoxy resin is used as the base material, with a VOC content of less than 50 g / L, meeting the requirements of environmental protection regulations. At the same time, the gel-like repair layer is mainly composed of sodium alginate and calcium chloride, belonging to environmentally friendly materials, reducing the impact on the environment.

[0022] The present invention has achieved breakthroughs in the dispersion stability, self-healing function, and adhesion of the repair layer of the waterborne anti-corrosion coating. Description of the Drawings

[0023] Figure 1 is the comparison of the sedimentation rate (%) of the waterborne anti-corrosion coating in the present invention; Figure 2 is the comparison of the uniformity of zinc powder distribution (%) of the waterborne anti-corrosion coating in the present invention; Figure 3 is the comparison of the storage stability of the waterborne anti-corrosion coating in the present invention; Figure 4 is the comparison of the self-healing efficiency (%) of the waterborne anti-corrosion coating in the present invention; Figure 5 is the comparison of the impedance recovery rate (%) of the waterborne anti-corrosion coating in the present invention; Figure 6 is the comparison of the multiple repair capabilities of the waterborne anti-corrosion coating in the present invention; Figure 7 is the comparison of the adhesion strength of the repair layer of the waterborne anti-corrosion coating in the present invention (MPa); Figure 8 is the comparison of the anti-scouring performance of the repair layer of the waterborne anti-corrosion coating in the present invention (retained area %); Figure 9 is the comparison of the environmental adaptability of the repair layer of the waterborne anti-corrosion coating in the present invention (adhesion strength MPa after temperature cycling); Figure 10 is the comparison of the corrosion spread distance at the scratched area in the salt spray test of the waterborne anti-corrosion coating in the present invention (mm); Figure 11 is the comparison of the results of the electrochemical corrosion test of the waterborne anti-corrosion coating in the present invention (after 500 hours of immersion); Figure 12 is the performance change after the artificial accelerated aging test of the waterborne anti-corrosion coating in the present invention (after 1000 hours) Figure 13is the extreme temperature adaptability test result (adhesion retention rate %) in the present invention; Figure 14 is the temperature cycle shock test result (after 30 cycles) in the present invention; Figure 15 is the high salinity environment test result (impedance retention rate %, after 30 days) in the present invention; Figure 16 is the freeze - thaw cycle test result (after 20 cycles) in the present invention; Figure 17 is the comparison of VOC content of the water - borne anticorrosive coating in the present invention; Figure 18 is the comparison of heavy metal dissolution amount of the water - borne anticorrosive coating in the present invention (accumulated for 30 days, mg / m²); Figure 19 is the biocompatibility test result of the water - borne anticorrosive coating in the present invention; Figure 20 is the biodegradability test result (28 days) of the water - borne anticorrosive coating in the present invention. Detailed implementation manners

[0024] Now, the subject matter described herein will be discussed with reference to exemplary embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the protection scope of the content of this specification, changes can be made to the functions and arrangements of the elements discussed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0025] In at least one embodiment of the present invention, a preparation method of a water - borne anticorrosive coating doped with metal powder and porous particles is disclosed, including the following steps: I. Surface modification of porous silica particles and loading of zinc metal powder 1. Preparation of porous silica particles Porous silica particles with an average particle size of 200 or 350 or 500 nm (350 nm is selected in this embodiment), a specific surface area of 400 or 600 or 800 m² / g (600 m² / g is selected in this embodiment), and a pore diameter of 5 or 12 or 20 nm (12 nm is selected in this embodiment) are selected as the carrier material. The porous silica particles are vacuum - dried at 105 - 120 °C for 4 - 6 hours to remove the moisture adsorbed on their surfaces, obtaining dry porous silica particles.

[0026] 2. Surface modification of porous silica particles In this step, the surface of the porous silica particles is modified with a silane coupling agent to introduce functional groups that can form strong interactions with metallic zinc powder.

[0027] The specific steps are as follows: The dried porous silica particles are added to an anhydrous toluene solution containing 3 or 4 or 5 wt% (4 wt% is selected in this example) of γ-aminopropyltriethoxysilane (KH-550), and stirred and reacted at 70 or 75 or 80 °C (75 °C is selected in this example) for 8 or 10 or 12 hours (10 hours is selected in this example), so that the silane coupling agent undergoes a condensation reaction with the silanol groups on the silica surface, and amino groups are introduced onto the silica surface.

[0028] After the reaction is completed, the modified silica particles are collected by centrifugation and washed three times with anhydrous toluene and ethanol in sequence to remove the unreacted silane coupling agent.

[0029] The washed amino-functionalized silica particles are vacuum dried at 60 °C for 12 hours to obtain surface-modified porous silica particles.

[0030] It is confirmed by infrared spectroscopy that amino groups are successfully introduced onto the surface of the porous silica particles. These amino groups form a coordination interaction with the surface of the metallic zinc powder, enhancing the binding force between the zinc powder and the carrier.

[0031] 3. Loading of Metallic Zinc Powder In this step, the solvent thermal method is used to uniformly load metallic zinc powder onto the surface of the modified porous silica particles to form core-shell structured composite particles.

[0032] The specific steps are as follows: Spherical metallic zinc powder with a particle size of 1 or 2 or 3 μm (2 μm is selected in this example) and the modified porous silica particles are mixed at a weight ratio of 1:1 or 2:1 or 3:1 (2:1 is selected in this example), and added to anhydrous ethanol containing 0.5 or 1.2 or 2 wt% (1.2 wt% is selected in this example) of polyvinylpyrrolidone (PVP), and ultrasonically dispersed for 30 minutes to form a uniformly dispersed mixture.

[0033] The mixture is transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner and reacted at 120 or 135 or 150 °C (135 °C is selected in this example) for 6 or 7 or 8 hours (7 hours is selected in this example). During this process, PVP acts as a dispersant and a protective agent to prevent the aggregation of metallic zinc powder and at the same time promote its coordination interaction with the surface of the modified silica.

[0034] After the reaction is completed, it is cooled to room temperature, and the product is collected by centrifugation, washed three times with ethanol, and finally vacuum dried at 50 °C for 12 hours to obtain metallic zinc powder / porous silica core-shell structured composite particles.

[0035] The solvothermal method is used to promote the formation of a stable coordination structure between metallic zinc powder and amino-functionalized silica, rather than simple physical mixing. This structure enables the firm loading of metallic zinc powder on the surface of porous silica microparticles, improving the dispersion stability of metallic zinc powder in aqueous systems. Scanning electron microscopy and transmission electron microscopy analyses show that the metallic zinc powder is uniformly distributed on the surface of porous silica microparticles, forming a core-shell structure.

[0036] II. Preparation and Loading of Composite Microcapsules 1. Preparation of Sodium Alginate-Polypeptide Derivative Composite Microcapsules In this step, composite microcapsules containing sodium alginate and mussel foot protein polypeptide derivatives are prepared by interfacial polymerization, laying the foundation for the realization of the self-healing function and dual adhesion function of the biomimetic mucus layer.

[0037] The specific steps are as follows: Preparation of polypeptide derivatives: The adhesion polypeptide sequence (AKPSYPPTYK) in mussel foot protein is selected, and polypeptide derivatives are prepared by solid-phase peptide synthesis technology. The polypeptide is synthesized on an automatic peptide synthesizer using the Fmoc method, and then purified by high-performance liquid chromatography and freeze-dried to obtain a powdery polypeptide product.

[0038] Preparation of the aqueous phase: 2-4 wt% of sodium alginate is dissolved in deionized water, and then 0.2-0.5 wt% of the aforementioned polypeptide derivative is added. Stir at 40 °C for 2 hours to fully disperse the polypeptide derivative in the sodium alginate solution, obtaining a uniform aqueous phase.

[0039] Preparation of the oil phase: 5-8 wt% of polyurethane prepolymer (NCO-terminated) is dissolved in cyclohexane to obtain an oil phase.

[0040] Emulsification and interfacial polymerization: The aqueous phase is dropped into the oil phase containing 2-3 wt% of Span 80 emulsifier, emulsified for 30 minutes under high-speed stirring (2000-3000 rpm) to form a W / O emulsion. Then 1,4-butanediol is added as a crosslinking agent, and the reaction is carried out at 60 °C for 4 hours to cause the polymerization reaction of the polyurethane prepolymer at the water / oil interface, forming the microcapsule wall.

[0041] Product collection: After the reaction is completed, the microcapsules are collected by centrifugation, washed 3 times successively with cyclohexane and ethanol to remove unreacted substances and emulsifiers. Finally, vacuum-dry at 40 °C for 12 hours to obtain sodium alginate-polypeptide derivative composite microcapsules.

[0042] In this step, the mussel foot protein polypeptide derivative and sodium alginate are co-encapsulated in microcapsules, achieving the synergistic effect of the two functional components. Laser confocal microscopy observation and release behavior tests show that the prepared microcapsules have good encapsulation effects and corresponding wall film strengths, and will rupture and release the contents when the coating is damaged.

[0043] 2. Preparation of Calcium Chloride-Cyclodextrin Derivative Composite Microcapsules In this step, composite microcapsules containing calcium chloride and cyclodextrin derivatives are prepared by interfacial polymerization as another component with dual adhesion functions.

[0044] The specific steps are as follows: Preparation of cyclodextrin derivatives: Select β-cyclodextrin as the basis, and introduce functional groups capable of forming host-guest recognition with polypeptide derivatives through esterification reaction with p-aminobenzoic acid. Mix β-cyclodextrin and p-aminobenzoic acid in a molar ratio of 1:2 in DMF, add 1,1'-carbonyldiimidazole (CDI) as a condensing agent, and react at 60 °C for 24 hours. Then purify by precipitation and recrystallization methods to obtain cyclodextrin derivatives.

[0045] Aqueous phase preparation: Dissolve 5-8 wt% of calcium chloride and 0.3-0.6 wt% of cyclodextrin derivatives in deionized water and stir to form a homogeneous aqueous phase.

[0046] Oil phase preparation: Dissolve polymethyl methacrylate (PMMA) in dichloromethane to obtain an oil phase.

[0047] Emulsification and microcapsule formation: Drop the aqueous phase into the oil phase containing Tween 80 emulsifier, stir at high speed to form a W / O emulsion, and then form microcapsules by solvent evaporation method. Stir the emulsion at room temperature for 6-8 hours to slowly volatilize dichloromethane, and PMMA deposits at the water / oil interface to form the microcapsule wall.

[0048] Product collection: Collect the microcapsules by centrifugation, wash them, and vacuum dry them at 40 °C for 12 hours to obtain calcium chloride-cyclodextrin derivative composite microcapsules.

[0049] In this step, cyclodextrin derivatives and calcium chloride are co-encapsulated in microcapsules, enabling them to act synergistically with the contents of sodium alginate-polypeptide derivative microcapsules when the coating is damaged, form a gel-like repair layer, and enhance the adhesion of the repair layer through host-guest recognition.

[0050] 3. Loading of Composite Microcapsules In this step, the two composite microcapsules are respectively loaded into different pore regions of porous silica microparticles by a stepwise impregnation technique to achieve the self-healing function of the biomimetic mucus layer.

[0051] The specific steps are as follows: Loading of sodium alginate-polypeptide derivative composite microcapsules: Immerse the zinc powder / porous silica composite particles prepared in step 4.1 in an ethanol solution containing sodium alginate-polypeptide derivative composite microcapsules (concentration: 2-5 wt%), ultrasonically treat for 20 minutes at room temperature, and then continue to immerse for 2 hours under reduced pressure to allow the microcapsules to enter the pores of the porous silica. Subsequently, centrifuge to collect the product and vacuum dry at 40 °C for 6 hours to obtain an intermediate product loaded with sodium alginate-polypeptide derivative composite microcapsules.

[0052] Loading of calcium chloride-cyclodextrin derivative composite microcapsules: Immerse the intermediate product obtained in the previous step in an ethanol solution containing calcium chloride-cyclodextrin derivative composite microcapsules (concentration: 3-6 wt%), repeat a similar immersion process, but control the immersion time to 1 hour. This differential treatment ensures the layered distribution of the two types of microcapsules in the porous carrier and prevents them from coming into contact and reacting prematurely during the preparation process.

[0053] Product collection: Centrifuge to collect the final product, wash it once with ethanol, and vacuum dry at 40 °C for 12 hours to obtain zinc powder / porous silica composite particles loaded with both composite microcapsules.

[0054] By adjusting the immersion sequence, time, and solution concentration, this step achieves the differential distribution of the two composite microcapsules in the porous carrier, with the sodium alginate-polypeptide derivative composite microcapsules mainly distributed in the deeper pore regions and the calcium chloride-cyclodextrin derivative composite microcapsules mainly distributed in the relatively surface pore regions. This distribution pattern ensures that the two types of microcapsules are isolated from each other under normal coating conditions and can only come into contact and react when the coating is damaged, thus achieving self-healing on demand.

[0055] III. Preparation of waterborne anticorrosive coating and coating self-healing process 1. Preparation of waterborne anticorrosive coating In this step, the functional composite particles prepared previously are formulated into a waterborne anticorrosive coating. Compared with the general method for preparing anticorrosive coatings, this step controls the shear force and reaction temperature to protect the integrity of the microcapsules.

[0056] The specific steps are as follows: Preparation of the resin system: Select a waterborne epoxy resin as the film-forming base material, dilute it with water to a solid content of 40-50 wt%, then add an appropriate amount of wetting and dispersing agent (such as polyethylene glycol) and defoamer, and stir evenly at low speed to obtain a basic resin system.

[0057] Dispersion of composite particles: The composite particles prepared in step 4.2 (metal zinc powder / porous silica composite particles loaded with two kinds of microcapsules) were slowly added to the above resin system at 20 - 30 wt% of the total solid content, and stirred for 30 minutes under low shear force conditions (300 - 500 rpm) to ensure the uniform dispersion of the composite particles without damaging the microcapsules.

[0058] Addition of additives: Add additives such as thickeners, pH regulators, and antifreeze agents, and continue to stir at low speed for 15 minutes to fully mix each component.

[0059] Addition of curing agent: Add a water-dispersible epoxy curing agent (such as water-dispersible polyamide) to the above mixture and stir evenly to obtain the final waterborne anti-corrosion coating. The solid content of the coating is controlled at 55 - 65 wt%, the pH value is adjusted to 7.5 - 8.5, and the viscosity is controlled at 1500 - 2500 mPa·s.

[0060] Through the above preparation method, the obtained waterborne anti-corrosion coating has storage stability and construction performance. Compared with general zinc powder anti-corrosion coatings, no obvious sedimentation and stratification phenomenon occurred after this coating was placed for 30 days, and the uniformity of zinc powder distribution was greater than 90%.

[0061] 2. Coating self-healing process The self-healing process of this embodiment is based on the concept of bionic mucus layer and dual adhesion technology, which is the core function of the present invention. Its working process is as follows: Protective effect in normal state: When the coating is intact, the metal zinc powder protects the metal substrate through sacrificial anode action, and the porous silica particles form a physical barrier to prevent the penetration of corrosive media. At this time, the two composite microcapsules are located in different regions of the porous carrier respectively, isolated from each other and do not react.

[0062] Self-healing process in damaged state: When the coating is mechanically damaged, the cutting force causes the microcapsules to rupture and release the contents. First, the polypeptide derivative released by the sodium alginate-polypeptide derivative composite microcapsule forms an initial anchoring layer on the surface of the exposed metal substrate to provide temporary protection. Subsequently, sodium alginate reacts with calcium chloride to undergo a gelation reaction to form a gel-like repair layer similar to the mucus secreted by marine organisms to fill the cracks.

[0063] Dual adhesion enhancement process: At the same time, the cyclodextrin derivative and the polypeptide derivative undergo a host-guest recognition reaction to form a supramolecular complex, enhancing the binding force between the gel layer and the metal substrate. This dual adhesion makes the repair layer maintain integrity under conditions such as water flow scouring or mechanical friction.

[0064] Synergistic anti-corrosion process: The formed gel-like repair layer has a certain semi-permeability, allowing zinc ions to slowly diffuse and undergo an ion exchange reaction with sodium alginate to form a denser zinc ion complex protective layer, further enhancing the anti-corrosion effect.

[0065] Through the above multi-stage synergistic effect, this embodiment achieves comprehensive protection of the metal substrate. Dynamic mechanical analysis shows that the repaired coating restores approximately 85% of its original barrier performance, which is higher than the repair efficiency of conventional self-healing coatings (usually 40 - 60%). At the same time, the adhesion strength of the repair layer reaches more than 2.5 MPa, maintaining good integrity under water flow scouring conditions.

[0066] Experimental verification To confirm the advantages of the present invention in terms of technical effects, we designed and conducted a series of experiments and tests, systematically verifying six aspects including dispersion stability, self-healing function, adhesion of the repair layer, comprehensive anti-corrosion performance, environmental adaptability, and environmental friendliness. The methods, steps, and results of each experiment are introduced in detail below.

[0067] I. Experimental verification of dispersion stability Experimental purpose: To evaluate the dispersion stability of metallic zinc powder in the waterborne anti-corrosion coating prepared in this embodiment and compare it with ordinary waterborne zinc powder coatings in the prior art.

[0068] Experimental materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles); Sample B: Conventional waterborne zinc powder coating (dispersing metallic zinc powder by directly adding a dispersant); Sample C: Commercial waterborne zinc powder anti-corrosion coating (commercially available product); Experimental equipment: Thermostatic oven (25 ± 2 °C); Laser particle size analyzer (Malvern Mastersizer 3000); Centrifugal sedimentation analyzer (LUMiSizer 651); High-precision electronic balance (accuracy 0.0001 g); Glass graduated cylinder (100 mL).

[0069] Experimental method: Sedimentation rate test: After stirring each sample evenly, pour it into a 100 mL graduated cylinder to the 80 mL mark; Place the graduated cylinder in the thermostatic oven and let it stand at 25 ± 2 °C; Observe the sedimentation situation and measure the height of the supernatant respectively after 0, 7, 15, and 30 days; Calculate the sedimentation rate = (height of supernatant / total height) × 100%; Test for uniformity of zinc powder distribution: After stirring each sample evenly, samples are taken from the upper, middle, and lower positions of the coating respectively; The zinc powder content at each position is measured using a centrifugal sedimentation analyzer; Calculate the zinc powder distribution uniformity = (lowest content / highest content) × 100%; Storage stability test: Seal and store each sample under the condition of 25 ± 2°C; After 3 months and 6 months respectively, test the viscosity change and zinc powder sedimentation of the coating; Record whether phenomena such as stratification and caking occur in the coating; Experimental results: See Figure 1 Comparison of sedimentation rates of waterborne anticorrosive coatings (%); See Figure 2 Comparison of zinc powder distribution uniformity of waterborne anticorrosive coatings (%); See Figure 3 Comparison of storage stability of waterborne anticorrosive coatings.

[0070] Result analysis: From Figures 1-3 the experimental results, it can be seen that the waterborne anticorrosive coating (Sample A) prepared in this embodiment is significantly superior to the conventional waterborne zinc powder coating (Sample B) and the commercial waterborne zinc powder coating (Sample C) in terms of dispersion stability. Specifically manifested as: In terms of sedimentation rate, after 30 days of static settlement, the sedimentation rate of Sample A is only 4.5%, while the sedimentation rates of Sample B and Sample C reach 24.6% and 18.9% respectively. This shows that the core-shell structure formed by surface modification of porous silica particles and loading of metallic zinc powder by solvothermal method in this embodiment effectively solves the sedimentation problem of metallic zinc powder.

[0071] In terms of zinc powder distribution uniformity, after 30 days, Sample A still maintains a uniformity of 92.8%, while Sample B and Sample C drop to 75.1% and 80.7% respectively. This indicates that the core-shell structure composite particles in this embodiment have better dispersibility and stability in the aqueous system.

[0072] In terms of storage stability, Sample A still maintains a good state after 6 months, with a viscosity change rate of only 8.7% and only slight sedimentation in appearance; while Sample B shows obvious sedimentation after 3 months and hard sedimentation after 6 months, and is not easily redispersed, and the performance of Sample C is between the two.

[0073] These results prove that by constructing a core-shell structure of metallic zinc powder and surface-modified porous silica particles in this embodiment, the long-term dispersion stability of metallic zinc powder in the waterborne epoxy system is achieved, the sedimentation problem existing in the prior art of zinc powder waterborne anticorrosive coatings is solved, and the storage period of the coating is extended.

[0074] II. Experimental Verification of Self-Healing Function Experimental Purpose: To evaluate the self-healing ability of the waterborne anti-corrosion coating in this embodiment, including repair efficiency, repair speed and multiple repair ability, and compare it with the existing self-healing anti-corrosion coatings.

[0075] Experimental Materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles); Sample D: Ordinary self-healing anti-corrosion coating containing microcapsules (commercially available product); Sample E: Ordinary waterborne epoxy anti-corrosion coating without self-healing components (control group).

[0076] Experimental Equipment: Thermostatic and Humidistatic Chamber (25±2°C, relative humidity 65±5%); Scratch Tester (scratch width 100μm, depth reaching the substrate surface); Electrochemical Workstation (Gamry Reference 600+); Optical Microscope (Olympus BX53M); Electron Microscope (Zeiss EVO 18); Automatic Film Coater (uniform coating thickness 200±10μm).

[0077] Experimental Methods: Self-Healing Efficiency Test: Coat each sample evenly on the pretreated Q235 steel plate with an automatic film coater, and the dry film thickness is 200±10μm; Cure at 25±2°C and relative humidity 65±5% for 7 days; Use a scratch tester to create artificial scratches with a width of 100μm and a depth reaching the substrate surface on the coating surface; Place the damaged samples in a thermostatic and humidistatic environment (25±2°C, relative humidity 65±5%); Observe the scratch repair situation using an optical microscope at 6 hours, 12 hours, 24 hours, and 48 hours after damage respectively; Calculate the self-healing efficiency = (repair area / initial scratch area) × 100%; Electrochemical Impedance Test: Use an electrochemical workstation to measure the electrochemical impedance spectra (EIS) of the intact coating, damaged coating and repaired coating; Test Conditions: In 3.5% NaCl solution, frequency range 10-2-105Hz, test area 1cm²; Calculate the impedance recovery rate = (impedance value of the repaired coating / impedance value of the intact coating) × 100%; Multiple Repair Ability Test: Cause scratch damage repeatedly at the same position (after each repair); Record the self-healing efficiency and impedance recovery rate after each repair; Determine the maximum number of damage-repair cycles that can maintain effective repair; Experimental results: See Figure 4 Comparison of self-healing efficiency of waterborne anti-corrosion coatings (%); See Figure 5 Comparison of impedance recovery rate of waterborne anti-corrosion coatings (%); See Figure 6 Comparison of the multiple repair capabilities of waterborne anti-corrosion coatings.

[0078] Result analysis: From Figures 4-6 The experimental results show that the waterborne anti-corrosion coating (Sample A) prepared in this embodiment is significantly superior to the ordinary self-healing anti-corrosion coating (Sample D) and the ordinary epoxy coating (Sample E) in terms of self-healing function. Specifically manifested in: In terms of self-healing efficiency, the repair efficiency of Sample A reached 85.7% within 24 hours after damage and further increased to 92.3% after 48 hours, while the repair efficiencies of Sample D were only 56.2% (24 hours) and 61.8% (48 hours). This indicates that the biomimetic mucus layer self-healing mechanism designed in this embodiment has a higher repair efficiency. Electron microscope observations show that the repaired area of Sample A is smoother and denser, and the repair layer is tightly bonded to the substrate.

[0079] In terms of impedance recovery rate, the impedance recovery rate of Sample A reached 86.2% after 48 hours, approaching the performance of the original coating, which is significantly higher than 58.9% of Sample D. This shows that the repair in this embodiment is not only physical filling, but also restores the electrochemical barrier performance of the coating, providing more effective anti-corrosion protection.

[0080] In terms of multiple repair capabilities, after 5 consecutive damage-repair cycles, Sample A still maintained a repair efficiency of 45.3% and an impedance recovery rate of 41.8%, while the repair ability of Sample D decreased sharply after the 3rd time and almost lost the repair function at the 5th time. This proves that the two-component microcapsule system and hierarchical distribution structure constructed in this embodiment endow the coating with a more durable self-healing ability.

[0081] These results verify the effectiveness of the biomimetic mucus layer self-healing function and double adhesion enhancement mechanism adopted in this embodiment, which not only improves the single repair efficiency, but also extends the service life of the coating, enabling it to still maintain good anti-corrosion performance after multiple damages. This is of great significance for equipment and structures that require long-term protection and are difficult to maintain frequently.

[0082] III. Experimental verification of the adhesion of the repair layer Experimental purpose: To evaluate the adhesion and erosion resistance of the waterborne anti-corrosion coating repair layer of this embodiment, verify the effectiveness of the dual adhesion enhancement mechanism, and compare it with conventional self-healing anti-corrosion coatings.

[0083] Experimental materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles); Sample D: Ordinary self-healing anti-corrosion coating containing microcapsules (commercially available product); Sample F: Self-healing anti-corrosion coating containing commercial adhesives (comparative sample).

[0084] Experimental equipment: Tensile adhesion tester (PosiTest AT-A); Water flow erosion simulation device (adjustable flow rate 0 - 10 L / min); Environmental simulation chamber (adjustable temperature -30~80°C, humidity 30 - 95%RH); Digital microscope (Keyence VHX-7000); Scratch tester (scratch width 100μm, depth reaching the substrate surface).

[0085] Experimental methods: Tensile adhesion test: Uniformly coat each sample on the pretreated Q235 steel plate with a dry film thickness of 200 ± 10μm; Cure for 7 days at 25 ± 2°C and relative humidity 65 ± 5%; Use a scratch tester to create artificial scratches on the coating surface, place it in a constant temperature and humidity environment for 48 hours to complete self-healing; Attach a test cylinder with a diameter of 20mm to the repair area (using epoxy glue for bonding); Use a tensile adhesion tester to measure the adhesion strength between the repair layer and the substrate; Repeat the test 5 times for each sample and take the average value; Water flow erosion test: For the coating samples prepared and repaired according to the above method, after 48 hours of complete self-healing; Fix the sample on the water flow erosion simulation device and let the water flow (3.5% NaCl solution) impact the repair area vertically at different flow rates (2, 5, 8 L / min); Erode for 30 minutes at each flow rate, observe and record the loss of the repair layer; Use a digital microscope to observe the integrity of the repair layer after erosion; Calculate the percentage of the area of the repair layer retained after erosion; Environmental adaptability test: On the samples that have completed self-healing, conduct the following environmental adaptability tests: Temperature cycle test: Alternating between -20°C and 60°C, one cycle every 8 hours, for a total of 5 cycles; Humid heat cycle test: Alternating between 60°C / 95%RH and 25°C / 50%RH, one cycle every 12 hours, for a total of 5 cycles; After each cycle, check the integrity of the repair layer and test the adhesion strength.

[0086] Experimental results: See Figure 7 Comparison of the adhesion strength of the repair layer of waterborne anti-corrosion coatings (MPa); See Figure 8 Comparison of the erosion resistance of the repair layer of waterborne anti-corrosion coatings (retained area %); See Figure 9 Comparison of the environmental adaptability of the repair layer of waterborne anti-corrosion coatings (adhesion strength in MPa after temperature cycle).

[0087] Result analysis: From Figures 7-9 the experimental results, it can be seen that the waterborne anti-corrosion coating (Sample A) prepared in this embodiment is significantly superior to the ordinary self-healing anti-corrosion coating (Sample D) and the self-healing coating containing commercial adhesives (Sample F) in terms of the adhesion of the repair layer. Specifically manifested as: In terms of the adhesion strength of the repair layer, the adhesion strength of the repair layer of Sample A reaches 2.7 MPa, which is 84.4% of the intact coating, significantly higher than 1.2 MPa (40.0%) of Sample D and 1.8 MPa (58.1%) of Sample F. This proves that the dual adhesion enhancement mechanism (host-guest recognition between mussel foot protein polypeptide derivative and cyclodextrin derivative) adopted in this embodiment effectively improves the binding force between the repair layer and the substrate.

[0088] In terms of erosion resistance, under the water flow scouring condition of 5 L / min, the retention rate of the repair layer of Sample A is 92.5%, while those of Sample D and Sample F are only 52.8% and 75.4% respectively. Even at a high flow rate of 8 L / min, Sample A still maintains 83.7% integrity of the repair layer, which is particularly important for anti-corrosion protection in marine environments or the inner walls of fluid transportation pipelines.

[0089] In terms of environmental adaptability, after 5 temperature cycles, the adhesion strength of the repair layer of Sample A still remains at 2.1 MPa, with a decrease amplitude of only 22.2%, while the adhesion strengths of Sample D and Sample F decrease to 0.4 MPa and 0.8 MPa respectively, with decrease amplitudes of 66.7% and 55.6% respectively. This indicates that the repair layer of this embodiment has better stability under temperature fluctuation conditions and can adapt to more severe environmental conditions.

[0090] These results strongly demonstrate the effectiveness of the dual adhesion enhancement mechanism adopted in this embodiment, that is, through the mussel foot protein polypeptide derivative, an initial anchoring layer is first formed with the metal substrate, and then a supramolecular complex is formed with the cyclodextrin derivative through host-guest recognition, further enhancing the adhesion and stability of the repair layer. This innovative design enables the repair layer to maintain integrity under harsh conditions such as water flow scouring and temperature fluctuations, significantly extending the effective protection period of the anti-corrosion coating.

[0091] IV. Experimental Verification of Comprehensive Anti-Corrosion Performance Experimental Purpose: To evaluate the comprehensive anti-corrosion performance of the waterborne anti-corrosion coating in this embodiment, including salt spray test, electrochemical corrosion test and artificial accelerated aging test, and to verify the effectiveness of the constructed three-level protection system.

[0092] Experimental Materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles); Sample D: Ordinary self-healing anti-corrosion coating containing microcapsules (commercially available product); Sample G: Conventional zinc powder anti-corrosion coating (commercially available product); Sample E: Ordinary waterborne epoxy anti-corrosion coating without self-healing components (control group).

[0093] Experimental Equipment: Salt spray test chamber (compliant with ASTM B117 standard); Electrochemical workstation (Gamry Reference600+); UV accelerated aging chamber (Q-Lab QUV / se); Digital microscope (Keyence VHX-7000); Electronic balance (accuracy 0.0001g); Coating thickness gauge (Elcometer 456).

[0094] Experimental Methods: Salt Spray Test: Each sample was evenly coated on a pretreated Q235 steel plate with a dry film thickness of 200 ± 10 μm; Artificial scratches (width 1 mm, depth reaching the substrate surface) were made at the edge and center of the sample; The test was carried out in a salt spray test chamber according to ASTM B117 standard (5% NaCl solution, 35 ± 2 °C); The samples were taken out and observed at 100 hours, 300 hours, 500 hours, 750 hours and 1000 hours respectively; The corrosion spreading distance from the scratch to both sides was measured; The coating protection grade was evaluated according to ASTM D1654 standard; Electrochemical Corrosion Test: Samples identical to those in the salt spray test were prepared, and artificial scratches were made at the center of the samples; The following tests were carried out in 3.5% NaCl solution using an electrochemical workstation: Open circuit potential (OCP) monitoring: Record the change in potential of the sample during immersion. Tafel polarization curve test: Scanning range ±250 mV vs OCP, scanning rate 0.5 mV / s. Electrochemical impedance spectroscopy (EIS) test: Frequency range 10⁻² - 10⁵ Hz. Calculate the corrosion current density and corrosion rate based on the polarization curve. Analyze the EIS data through an equivalent circuit model to evaluate the barrier performance of the coating. Artificial accelerated aging test: Place the coated sample in an ultraviolet accelerated aging chamber. Cycling conditions: Ultraviolet irradiation (60 ± 3 °C, 8 hours) and condensation (50 ± 3 °C, saturated humidity, 4 hours). Total test time: 1000 hours. Take out the sample every 200 hours for performance evaluation: Appearance changes: Gloss, cracking, chalking, and yellowing, etc. Adhesion test: Test according to ASTM D4541 standard. Make scratches on the aged sample to evaluate the retention rate of the self-healing ability.

[0095] Experimental results: See Figure 10 Comparison of the corrosion spread distance at the scratched area in the salt spray test (mm); See Figure 11 Comparison of the electrochemical corrosion test results (after 500 hours of immersion); See Figure 12 Performance changes after artificial accelerated aging test (after 1000 hours).

[0096] Result analysis: From Figures 10-12 the experimental results, it can be seen that the waterborne anti-corrosion coating (sample A) prepared in this embodiment is significantly superior to other comparative samples in terms of comprehensive anti-corrosion performance. Specifically manifested in: In terms of salt spray protection performance, after 1000 hours of salt spray test, the corrosion spread distance of sample A was only 1.7 mm, while those of sample D, sample G and sample E were 5.5 mm, 7.8 mm and 9.3 mm respectively. This indicates that the three-level protection system (sacrificial anode protection of metallic zinc powder, physical barrier of porous carrier, self-healing repair layer) constructed in this embodiment provides more comprehensive corrosion protection, especially showing obvious advantages under long-term exposure conditions. It is worth noting that during the test of sample A, white protective zinc salt deposits gradually formed at the scratched areas, effectively preventing further corrosion development.

[0097] In terms of electrochemical anti-corrosion performance, after 500 hours of immersion, sample A still maintained a low corrosion current density (0.32 μA / cm²) and a high impedance modulus (3.5×10 7 Ω·cm²), indicating that the coating has excellent anti-corrosion barrier performance. In contrast, the electrochemical properties of other samples all decreased to a large extent. This result confirms that the repair layer formed after coating damage in this embodiment not only physically fills the defects, but also forms an electrochemically stable protection layer through a dual adhesion mechanism, effectively blocking the penetration of corrosive media.

[0098] In terms of long-term weather resistance, after 1000 hours of accelerated aging test, the retention rates of various properties of sample A were higher than those of other samples. Especially, the retention rate of self-healing efficiency reached 79.7%, while that of sample D was only 40.0%. This shows that the microcapsule system designed in this embodiment has better stability under environmental factors such as ultraviolet radiation and humid heat cycling, can continuously provide self-healing function, and extend the protection life of the coating.

[0099] Based on the above results, the three-level protection system constructed in this embodiment realizes multiple synergistic anti-corrosion through the sacrificial anode protection of metallic zinc powder, the physical barrier effect of porous carrier, the self-healing repair of biomimetic mucus layer and the enhanced effect of dual adhesion, and shows excellent protection performance and durability under various corrosion environments and accelerated aging conditions, providing all-round and long-term effective anti-corrosion protection for metal substrates.

[0100] V. Experimental Verification of Environmental Adaptability Experimental purpose: To evaluate the adaptability and protection performance of the waterborne anti-corrosion coating in this embodiment under various extreme environmental conditions, and verify its applicability in different usage scenarios.

[0101] Experimental materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles); Sample D: A common self-healing anti-corrosion coating containing microcapsules (commercially available product); Sample G: A conventional zinc powder anti-corrosion coating (commercially available product); Experimental equipment: High and low temperature humidity test chamber (temperature adjustable from -60 to 150 °C, humidity 10 - 98%RH); Salt water immersion device (salinity adjustable from 0 to 10%); Thermal cycle shock test device; Freezing-thawing cycle test device; Electrochemical workstation (Gamry Reference 600+); Adhesion tester (PosiTest AT-A).

[0102] Experimental methods: Extreme temperature adaptability test: Coat each sample evenly on the pretreated Q235 steel plate with a dry film thickness of 200 ± 10 μm; Expose the samples to the following temperature conditions for 24 hours respectively: Low temperature environment: -40 ± 2 °C; High temperature environment: 80 ± 2 °C; Test the changes in adhesion and anti-corrosion performance of the coating before and after exposure; Temperature cycle shock test: The coated samples are cycled between -40 °C and 80 °C, each temperature is maintained for 2 hours, and direct conversion (no gradient); A total of 30 cycles are carried out, and the total test time is 120 hours; Check the coating appearance, adhesion changes and whether there are cracks, peeling and other phenomena every 10 cycles; High salinity environment test: Immerse the samples in NaCl solutions with different concentrations (3.5%, 5% and 10%); The immersion time is 30 days, and take them out every 7 days to measure the electrochemical impedance; Calculate the decay rate of impedance with the change of immersion time and salinity; Freezing-thawing cycle test: Immerse the samples in 3.5% NaCl solution for 2 hours first; Then freeze them in an environment of -20 °C for 16 hours; Then melt them in an environment of 25 °C and 65%RH for 6 hours; Repeat the above cycle 20 times, and test the coating performance changes after every 5 cycles; Experimental results: See Figure 13 Results of extreme temperature adaptability test (adhesion retention rate %); See Figure 14 Results of temperature cycle shock test (after 30 cycles); See Figure 15 Results of high salinity environment test (impedance retention rate %, after 30 days); See Figure 16Results of freeze-thaw cycle test (after 20 cycles).

[0103] Result analysis: From Figures 13-16 the experimental results, it can be seen that the waterborne anti-corrosion coating (Sample A) prepared by this embodiment exhibits excellent adaptability and stability under various extreme environmental conditions, significantly superior to the comparative samples. Specifically manifested as follows: Under extreme temperature conditions, the adhesion retention rate of Sample A remains above 90%, indicating that the coating can maintain excellent structural stability under both low-temperature embrittlement and high-temperature softening conditions. This benefits from the use of porous silica microparticles as carriers in this embodiment, providing excellent temperature buffering ability, as well as the stable structural design of the composite microcapsules.

[0104] In the temperature cycle shock test, after 30 severe temperature cycles, Sample A did not show cracking and peeling phenomena, and the retention rates of adhesion and self-healing function reached 83.6% and 76.5% respectively, while other samples showed varying degrees of performance degradation and surface defects. This indicates that the coating of this embodiment has excellent temperature strain adaptability and structural integrity.

[0105] In a high-salinity environment, as the NaCl concentration increases, the impedance retention rates of all samples show a downward trend, but the decline of Sample A is the smallest. Even in an extremely high-salinity environment of 10% NaCl, it still maintains an impedance retention rate of 63.8%. This shows that the three-level protection system designed in this embodiment can continuously provide effective anti-corrosion protection in a high-salinity environment, especially suitable for the use requirements of ocean engineering and coastal industrial facilities.

[0106] In the freeze-thaw cycle test, Sample A also showed the best stability. After 20 severe freeze-thaw cycles, the retention rates of adhesion, impedance, and self-healing efficiency all remained at a high level (81.2%, 79.5%, and 72.8% respectively). This result is of great significance for the application of the coating in areas or equipment with severe seasonal freeze-thaw changes.

[0107] Based on the above results, the waterborne anti-corrosion coating of this embodiment realizes excellent adaptability under various extreme environmental conditions through innovative material design and structural optimization, can meet the anti-corrosion requirements of different application scenarios, especially suitable for industrial facilities, ocean engineering structures, and oil pipelines in cold regions with complex and harsh environmental conditions, and has broad application prospects.

[0108] VI. Experimental verification of environmental protection performance Experimental purpose: To evaluate the environmental protection performance of the waterborne anti-corrosion coating of this embodiment, including aspects such as VOC content, heavy metal dissolution amount, and biocompatibility, and verify its compliance with environmental protection regulations.

[0109] Experimental materials: Sample A: The waterborne anti-corrosion coating prepared in this embodiment (containing core-shell structure composite particles) Sample G: Conventional zinc powder anti-corrosion coating (commercially available product) Sample H: Solvent-based epoxy zinc powder anti-corrosion coating (comparative sample) Experimental equipment: Gas chromatography-mass spectrometry (GC-MS); Atomic absorption spectrometer (AAS); Total organic carbon analyzer (TOC); Biotoxicity test system; Fourier transform infrared spectrometer (FTIR).

[0110] Experimental methods: VOC content test: Determine the VOC content of each sample according to the EPA Method 24 standard; Analyze the specific composition of volatile organic compounds using gas chromatography-mass spectrometry; Calculate the VOC release rate and total release amount; Heavy metal leaching test: Coat each sample on a glass plate, and after drying and curing, soak it in a simulated acid rain solution with pH = 5.5; The soaking time is 30 days, and samples are taken every 7 days to analyze the heavy metal content such as zinc, lead, and chromium in the solution; Determine the metal ion concentration using an atomic absorption spectrometer; Calculate the metal leaching amount per unit area; Biocompatibility test: Prepare the coating extract (according to the ISO 10993-12 standard); Conduct zebrafish embryo toxicity test and algal growth inhibition test; Calculate the toxicity index and growth inhibition rate; Biodegradability test: After crushing the coating sample, conduct a degradation test under simulated natural environmental conditions; Monitor the carbon dioxide release amount and total organic carbon reduction amount within 28 days; Calculate the biodegradation rate; Experimental results: See Figure 17 Comparison of VOC content of waterborne anti-corrosion coatings; See Figure 18 Comparison of heavy metal leaching amounts of waterborne anti-corrosion coatings (accumulated for 30 days, mg / m²); See Figure 19 Biocompatibility test results of waterborne anti-corrosion coatings; See Figure 20 Biodegradability test results of waterborne anti-corrosion coatings (28 days).

[0111] Result analysis: From Figures 17-20 the experimental results, it can be seen that the waterborne anticorrosive coating (Sample A) prepared by this embodiment has obvious advantages in environmental performance and meets or even exceeds the requirements of relevant environmental protection regulations. Specifically manifested in: In terms of VOC content, the VOC content of Sample A is only 42 g / L, far lower than 380 g / L of the solvent-based coating (Sample H) and also lower than 85 g / L of the conventional waterborne zinc powder coating (Sample G), meeting the requirements of the strictest environmental protection regulations. This is mainly due to the use of waterborne epoxy resin as the base material in this embodiment and the fixation of functional components through porous carriers, minimizing the use of organic solvents to the greatest extent.

[0112] In terms of heavy metal leaching, the zinc ion leaching amount of Sample A (18.5 mg / m²) is significantly lower than that of Sample G (42.3 mg / m²) and Sample H (38.6 mg / m²), and almost no other harmful heavy metals are contained. This indicates that this embodiment effectively controls the release rate of metallic zinc powder through the core-shell structure, reducing the potential impact on the water environment.

[0113] In terms of biocompatibility, Sample A shows non-toxicity (LC50 > 100%) in the zebrafish embryo toxicity test, and the algal growth inhibition rate is only 12.5%, with a biotoxicity rating of 0 (non-toxic). In contrast, Samples G and H show slight and moderate toxicity respectively. This shows that the bio-based components (such as sodium alginate and mussel foot thread protein polypeptide derivatives) selected in this embodiment have good biocompatibility, reducing the harm to aquatic organisms.

[0114] In terms of biodegradability, the biodegradation rate of Sample A reaches 28.5%, higher than that of Sample G (21.3%) and Sample H (12.8%). This indicates that some components in the coating of this embodiment (especially the components of the gel-like repair layer) can be degraded by microorganisms in the natural environment, reducing the long-term environmental burden.

[0115] Based on the above results, the waterborne anticorrosive coating of this embodiment realizes excellent environmental performance through innovative material design and green chemistry principles, minimizing the negative impact on the environment while maintaining high-efficiency anticorrosive function. This not only meets the increasingly strict requirements of environmental protection regulations but also conforms to the concept of sustainable development, providing a new technical path for the green transformation of the anticorrosive coating industry.

[0116] Summary of experimental verification Through systematic experiments in the above six aspects, the waterborne anti-corrosion coating of metal powder-doped porous particles prepared in this embodiment has shown significant advantages in terms of dispersion stability, self-healing function, adhesion of the repair layer, comprehensive anti-corrosion performance, environmental adaptability, and environmental friendliness. The specific advantages can be summarized as follows: Dispersion stability: The design of composite particles based on the core-shell structure solves the sedimentation problem of metallic zinc powder in the waterborne epoxy system. The sedimentation rate is only 4.5% after 30 days, the uniformity of zinc powder distribution remains at 92.8%, and the storage period is extended to more than 6 months.

[0117] Self-healing function: The self-healing mechanism based on the concept of biomimetic mucus layer achieves a repair efficiency of 85.7% and an impedance recovery rate of 86.2%, and can be repaired multiple times (≥5 times), significantly extending the service life of the coating.

[0118] Adhesion of the repair layer: The dual adhesion enhancement mechanism improves the bonding force between the repair layer and the substrate. The adhesion strength of the repair layer reaches 2.7 MPa and maintains 92.5% integrity under the condition of water flow scouring at 5 L / min, showing excellent anti-scouring ability.

[0119] Comprehensive anti-corrosion performance: The three-level protection system shows excellent protection effects in both long-term salt spray exposure and immersion corrosion tests. After 1000 hours of salt spray test, the corrosion spread distance is only 1.7 mm. After 500 hours of immersion, the corrosion current density is only 0.32 μA / cm², and the electrochemical impedance is as high as 3.5×10 7 Ω·cm².

[0120] Environmental adaptability: Under harsh conditions such as extreme temperatures, temperature cycle shocks, high salinity environments, and freeze-thaw cycles, the coating performance retention rate is higher than that of the comparative sample, showing excellent environmental adaptability and being suitable for various complex working conditions.

[0121] Environmental friendliness: The VOC content is as low as 42 g / L, the zinc ion dissolution amount is only 18.5 mg / m², it is non-toxic to aquatic organisms, and some components are biodegradable, meeting the requirements of strict environmental protection regulations and reflecting the concept of green chemistry.

[0122] These experimental results fully verify the effectiveness of the three-level protection system based on porous carriers in this embodiment, break through the technical bottlenecks of existing waterborne zinc powder anti-corrosion coatings in terms of dispersion stability, self-healing function, and adhesion of the repair layer, and achieve the unity of high-efficiency anti-corrosion and environmental friendliness.

[0123] The embodiments of the present invention have been described above. However, these embodiments are not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative rather than restrictive. Under the inspiration of these embodiments, those of ordinary skill in the art can also make more equivalent embodiments in various forms, all of which fall within the protection scope of these embodiments.

Claims

1. A water-based anti-corrosion coating containing metal powder and porous particles. It is characterized in that include: Surface-modified porous silica particles loaded with metal zinc powder, wherein the surface-modified porous silica particles and the metal zinc powder form core-shell structure composite particles; Sodium alginate-polypeptide derivative composite microcapsules and calcium chloride-cyclodextrin derivative composite microcapsules loaded in the pores of the surface-modified porous silica particles, wherein the sodium alginate-polypeptide derivative composite microcapsules are mainly distributed in the deep region of the pores, and the calcium chloride-cyclodextrin derivative composite microcapsules are mainly distributed in the surface region of the pores; and water-based epoxy resin, wherein the core-shell structure composite particles are uniformly dispersed in the water-based epoxy resin.

2. The water-based anti-corrosion coating of metal powder doped with porous particles according to claim 1, characterized in that: The polypeptide derivative is a mussel byssin polypeptide derivative, and the polypeptide derivative and the cyclodextrin derivative can form a host-guest recognition effect.

3. The water-based anticorrosive coating according to claim 1, characterized in that: The surface-modified porous silica particles are prepared by surface-modifying the porous silica particles with a silane coupling agent, thereby introducing functional groups that form a coordination effect with the metal zinc powder.

4. The water-based anti-corrosion coating of metal powder doped with porous particles according to claim 3, characterized in that: The silane coupling agent is γ-aminopropyltriethoxysilane, and the functional group is amino group.

5. The water-based anti-corrosion coating of metal powder doped with porous particles according to claim 1, characterized in that: The porous silica particles have an average particle size of 200-500 nm, a specific surface area of ​​400-800 m2 / g, and a pore size of 5-20 nm.

6. The water-based anti-corrosion coating of metal powder doped with porous particles according to claim 1, characterized in that: The cyclodextrin derivative is a β-cyclodextrin derivative modified by p-aminobenzoic acid.

7. The water-based anti-corrosion coating of metal powder doped with porous particles according to claim 1, characterized in that: The water-based anti-corrosion coating has a solid content of 55-65 weight percent, a pH value of 7.5-8.5, and a viscosity of 1500-2500 mPa·s.

8. A method for preparing a water-based anti-corrosion coating containing metal powder and porous particles, characterized in that: The following steps are involved: Step 1: Surface modification of porous silica particles; Step 2: loading metal zinc powder on the surface of the surface-modified porous silica particles obtained in step 1 to form core-shell structured composite particles; Step 3: preparing sodium alginate-polypeptide derivative composite microcapsules and calcium chloride-cyclodextrin derivative composite microcapsules; Step 4: loading the two composite microcapsules obtained in step 3 into different pore regions of the core-shell structure composite particles obtained in step 2 respectively; Step 5: Disperse the core-shell structure composite particles loaded with composite microcapsules obtained in step 4 in water-based epoxy resin to obtain a water-based anti-corrosion coating.

9. The preparation method according to claim 8, characterized in that: The surface modification method in step 1 is: adding porous silica particles to an anhydrous toluene solution containing 3-5 weight percent of γ-aminopropyltriethoxysilane, stirring and reacting at 70-80° C. for 8-12 hours, so that the silane coupling agent reacts with the silanol groups on the surface of the silica to introduce amino functional groups.

10. The preparation method according to claim 8, characterized in that: The method for loading the metal zinc powder in step 2 is: mixing metal zinc powder with a particle size of 1-3 μm with surface modified porous silica particles in a weight ratio of 1:1-3:1, adding to anhydrous ethanol containing 0.5-2 weight percent polyvinyl pyrrolidone, and then ultrasonically dispersing and solvent thermally reacting at 120-150° C. for 6-8 hours.

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