Micro-nano anticorrosive coating and preparation method thereof

Abstract

This invention discloses a micro / nano anti-corrosion coating and its preparation method, belonging to the field of marine engineering anti-corrosion technology. It includes component A and component B. Component A comprises bisphenol F type epoxy resin, cashew phenol glycidyl ether, KH560 modified zinc phosphate, aminated nano-silica, aluminum tripolyphosphate, wetting and dispersing agent, anti-settling agent, composite UV stabilizer, and composite solvent. Component B comprises 100 parts of cashew phenol modified amine curing agent. This invention, using the aforementioned micro / nano anti-corrosion coating and its preparation method, achieves ultra-long salt spray resistance in marine atmospheric, splash, and full immersion conditions; significant self-inhibition ability of corrosion propagation after scratches; ultra-high interfacial bonding strength with metal substrates; and UV yellowing resistance that overcomes the weather resistance bottleneck of the cashew phenol system. It also possesses excellent industrial practicality and economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of marine engineering corrosion protection technology, and in particular to a micro / nano anti-corrosion coating and its preparation method. Background Technology

[0002] In marine environments, steel structures face multiple corrosive factors, including high salt spray, high humidity and heat, strong chloride ion penetration, marine organism attachment, and wave impact. Coating protection is the most economical and effective means of corrosion prevention. Epoxy-based anti-corrosion primers have become the mainstream choice in marine heavy-duty anti-corrosion coating systems due to their excellent adhesion, chemical resistance, and strong bonding ability with metal substrates.

[0003] However, existing commercially available zinc-free epoxy primers have the following technical drawbacks in practical applications: Traditional epoxy primers primarily rely on the resin matrix's own barrier properties against moisture and chloride ions, lacking a synergistic densification design using multi-scale fillers. Ordinary micron-sized fillers (such as zinc phosphate and talc) cannot form a complete and dense packing structure in coatings due to their uniform size; numerous micro-gaps and pores exist between particles, allowing moisture and chloride ions to easily penetrate into the metal matrix along these microscopic channels, leading to premature coating failure. While nanofillers (such as nano-silica) can theoretically fill the pores between micron-sized fillers, they readily aggregate in epoxy resins, making uniform dispersion difficult, and the actual shielding effect is far lower than theoretically expected. Summary of the Invention

[0004] The purpose of this invention is to provide a micro / nano anti-corrosion coating and its preparation method. Through a synergistic mechanism of full component equivalent matching, bicovalent interface anchoring, bisphosphate gradient passivation, and UV stabilization, the coating achieves ultra-long salt spray resistance, significant self-inhibition of corrosion propagation after scratches, ultra-high interfacial bonding strength with metal substrates, and UV yellowing resistance that overcomes the weather resistance bottleneck of the cashew phenol system. At the same time, it has excellent industrial applicability and economy, providing a high-performance, low-cost, and easy-to-produce overall solution for long-term corrosion protection of zinc-free epoxy primers in all marine environments.

[0005] To achieve the above objectives, the present invention provides a micro / nano anti-corrosion coating comprising component A and component B. By mass, component A comprises 45-60 parts of bisphenol F type epoxy resin, 8-15 parts of cashew nut shell glycidyl ether, 10-15 parts of KH560 modified zinc phosphate, 2-5 parts of aminated nano silica, 4-8 parts of aluminum tripolyphosphate, 0.3-0.8 parts of wetting and dispersing agent, 0.5-1.2 parts of anti-settling agent, and 0.3-0.6 parts of composite ultraviolet stabilizer, with the composite solvent making up the balance to 100 parts; component B comprises 100 parts of cashew nut shell modified amine curing agent.

[0006] Preferably, the ratio of the total amount of epoxy groups of bisphenol F epoxy resin and epoxy groups of cashew phenol glycidyl ether in component A to the amount of amine groups in component B is 1:(0.95-1.05).

[0007] Preferably, the bisphenol F type epoxy resin has an epoxy equivalent of 155-185 g / eq, the cashew phenol glycidyl ether has an epoxy value of 0.2-0.28 eq / 100g, the KH560 modified zinc phosphate has a coating rate of 1.5-2.5% and a flake diameter of 2-5 μm, the composite UV stabilizer is Tinuvin 1130 and Tinuvin 292 in a mass ratio of 2:1, and the composite solvent is a mixture of butyl acetate, xylene, and PMA in a volume ratio of 3:4:1.

[0008] The preparation method of the micro / nano anti-corrosion coating described above includes the following steps: S1. Preparation of KH560 modified zinc phosphate: Add micro-nano sheet zinc phosphate to a high-speed mixer, heat up, dilute KH560 with ethanol to a concentration of 50%, adjust the pH with glacial acetic acid, spray 2.0% of the micro-nano sheet zinc phosphate dilution into the micro-nano sheet zinc phosphate while stirring, continue stirring for 30 min, discharge, vacuum dry, and sieve to obtain KH560 modified zinc phosphate; S2. Mix bisphenol F epoxy resin with cashew phenol glycidyl ether, stir at low speed, then add half of the total mass of composite solvent, and then add wetting and dispersing agent, KH560 modified zinc phosphate and aluminum tripolyphosphate in sequence, and stir at medium speed to disperse to obtain a pre-wetting system. S3. While maintaining the rotation speed, add aminated nano-silica to the pre-wetting system obtained in S2 and continue to disperse. After dispersion, add an anti-settling agent and stir at high speed to disperse. After dispersion, a slurry is obtained. Grind the slurry and add the remaining composite solvent. Stir at low speed and sieve to obtain component A. S4. After substrate treatment, mix component A and component B to obtain coating. After the coating has cured, spray the coating onto the substrate surface.

[0009] Preferably, in S1, the temperature is raised to 80-100℃, the pH is adjusted to 5-6, the vacuum drying temperature is 80℃, the vacuum drying time is 2 hours, and it is passed through a 400-mesh sieve.

[0010] Preferably, in S2, the low-speed stirring speed is 500-800 rpm and the low-speed stirring time is 10-15 min, and the medium-speed stirring speed is 800-1000 rpm and the medium-speed stirring time is 10-15 min.

[0011] Preferably, in S3, the high-speed stirring speed is 1500-2000 rpm, the high-speed stirring time is 20-30 min, and the slurry is ground to a fineness of ≤20μm.

[0012] Preferably, in S3, the low-speed stirring time is 10-15 minutes, and the mixture is passed through a 150-mesh sieve.

[0013] Preferably, in S4, the maturation time is 10-15 min.

[0014] Therefore, the present invention employs the above-mentioned micro / nano anti-corrosion coating and its preparation method, which has the following beneficial effects: (1) A micro-nano dual-scale densely packed physical shielding layer constructed by micron-scale KH560 modified zinc phosphate and nano-scale aminated silica, combined with a diphosphate gradient passivation chemical protection system formed by modified zinc phosphate and aluminum tripolyphosphate, enables the physical barrier ability and chemical passivation ability of the coating to achieve deep synergy. (2) By utilizing the chemical bonding and anchoring effect of aminated nano silica, a high-density physical framework is constructed in situ at the damaged part of the coating, which effectively blocks the lateral spread of corrosion products. At the same time, the bisphosphate corrosion inhibitor system can quickly release phosphate ions when a small amount of water is immersed, and react with the exposed metal surface to generate a passivation layer of insoluble iron phosphate, thus blocking the expansion of corrosion cells from the chemical source. (3) A dual covalent interface anchoring strategy is adopted: On the one hand, KH560 silane coupling agent forms a cross-linked polymer layer on the surface of zinc phosphate and chemically bonds with the epoxy matrix; on the other hand, the active amino groups on the surface of aminated nano-silica undergo ring-opening addition with epoxy resin, firmly "anchoring" the nanoparticles to the cross-linked network. The dual chemical anchoring completely changes the passive filling mode of traditional inorganic fillers that rely solely on physical dispersion, transforming the filler-resin interface from weak bonding to strong covalent bonding, while effectively reducing the curing internal stress; (4) The composite UV stabilizer system effectively inhibits the photodegradation chain reaction of cashew phenol components through the dual effects of UV absorption and free radical capture, enabling the cashew phenol modified epoxy primer, which originally had insufficient weather resistance, to be used for a long time in harsh environments such as ship decks, superstructures, and offshore platform atmospheric areas that need to withstand strong UV radiation and high salt spray corrosion.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 These are the UV resistance yellowing test results of Examples 1-3 and Comparative Examples 1-7 of the present invention's micro-nano anti-corrosion coating and its preparation method; Figure 2 These are the scratch corrosion propagation width and seawater immersion verification test results of Examples 1-3 and Comparative Examples 1-7 of the present invention, which describe a micro / nano anti-corrosion coating and its preparation method. Figure 2(a) shows the scratch corrosion propagation width test results for Examples 1-3 and Comparative Examples 1-7. Figure 2 (b) shows the seawater immersion verification test results of Examples 1-3 and Comparative Examples 1-7. Detailed Implementation

[0017] This invention provides a micro / nano anti-corrosion coating, comprising component A and component B. By mass, component A comprises 45-60 parts of bisphenol F type epoxy resin, 8-15 parts of cashew phenol glycidyl ether, 10-15 parts of KH560 modified zinc phosphate, 2-5 parts of aminated nano silica, 4-8 parts of aluminum tripolyphosphate, 0.3-0.8 parts of wetting and dispersing agent, 0.5-1.2 parts of anti-settling agent, and 0.3-0.6 parts of composite ultraviolet light stabilizer, with the composite solvent to make up the balance to 100 parts; component B comprises 100 parts of cashew phenol modified amine curing agent.

[0018] In this invention, the ratio of the total amount of epoxy groups of bisphenol F epoxy resin and the total amount of epoxy groups of cashew phenol glycidyl ether in component A to the amount of amine groups in component B is 1:(0.95-1.05).

[0019] In this invention, the epoxy equivalent of bisphenol F type epoxy resin is 155-185 g / eq, the epoxy value of cashew phenol glycidyl ether is 0.2-0.28 eq / 100g, the coating rate of KH560 modified zinc phosphate is 1.5-2.5%, the flake diameter is 2-5 μm, the composite UV stabilizer is Tinuvin 1130 and Tinuvin 292 in a mass ratio of 2:1, and the composite solvent is butyl acetate mixed with xylene and PMA in a volume ratio of 3:4:1.

[0020] The preparation method of the micro / nano anti-corrosion coating described above includes the following steps: S1. Preparation of KH560 modified zinc phosphate: Add micro-nano sheet zinc phosphate to a high-speed mixer, heat up, dilute KH560 with ethanol to a concentration of 50%, adjust the pH with glacial acetic acid, spray 2.0% of the micro-nano sheet zinc phosphate dilution into the micro-nano sheet zinc phosphate while stirring, continue stirring for 30 min, discharge, vacuum dry, and sieve to obtain KH560 modified zinc phosphate; S2. Mix bisphenol F epoxy resin with cashew phenol glycidyl ether, stir at low speed, then add half of the total mass of composite solvent, and then add wetting and dispersing agent, KH560 modified zinc phosphate and aluminum tripolyphosphate in sequence, and stir at medium speed to disperse to obtain a pre-wetting system. S3. While maintaining the rotation speed, add aminated nano-silica to the pre-wetting system obtained in S2 and continue to disperse. After dispersion, add an anti-settling agent and stir at high speed to disperse. After dispersion, a slurry is obtained. Grind the slurry and add the remaining composite solvent. Stir at low speed and sieve to obtain component A. S4. After substrate treatment, mix component A and component B to obtain coating. After the coating has cured, spray the coating onto the substrate surface.

[0021] In this invention, in step S1, the temperature is raised to 80-100℃, the pH is adjusted to 5-6, the vacuum drying temperature is 80℃, the vacuum drying time is 2 hours, and the product is passed through a 400-mesh sieve.

[0022] In this invention, in S2, the low-speed stirring speed is 500-800 rpm and the low-speed stirring time is 10-15 min, while the medium-speed stirring speed is 800-1000 rpm and the medium-speed stirring time is 10-15 min.

[0023] In this invention, in step S3, the high-speed stirring speed is 1500-2000 rpm, the high-speed stirring time is 20-30 min, and the slurry is ground to a fineness of ≤20 μm.

[0024] In this invention, in step S3, the low-speed stirring time is 10-15 minutes, and the mixture is passed through a 150-mesh sieve.

[0025] In this invention, the curing time in S4 is 10-15 min.

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0027] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0028] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0029] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0030] Example 1 This invention provides a micro / nano anti-corrosion coating, comprising component A and component B. By mass, component A comprises: 52 parts bisphenol F type epoxy resin, 10 parts cashew phenol glycidyl ether, 13 parts KH560 modified zinc phosphate, 4 parts aminated nano silica, 6 parts aluminum tripolyphosphate, 0.5 parts wetting and dispersing agent, 0.8 parts anti-settling agent, 0.6 parts composite ultraviolet light stabilizer, and composite solvent to make up the balance to 100 parts.

[0031] The epoxy equivalent of bisphenol F epoxy resin is 165 g / eq, the epoxy value of cashew phenol glycidyl ether is 0.24 eq / 100 g, the coating rate of KH560 modified zinc phosphate is 2%, the wetting and dispersing agent is BYK-163, the anti-settling agent is fumed silica A200, the mass ratio of Tinuvin 1130 and Tinuvin 292 in the composite UV stabilizer is 2:1, and the volume ratio of butyl acetate, xylene and PMA in the composite solvent is 3:4:1.

[0032] Component B includes 100 parts of cashew phenol modified amine curing agent.

[0033] The preparation method of the above-mentioned micro / nano anti-corrosion coating includes the following steps: S1. Add the micro / nano-sheet zinc phosphate to a high-speed mixer and heat to 90℃. Dilute KH560 with ethanol to a concentration of 50%. Adjust the pH to 5.5 with glacial acetic acid. Spray 2.0% of the zinc phosphate dilution solution onto the micro / nano-sheet zinc phosphate, stir for 30 min, vacuum dry at 80℃ for 2 h, and pass through a 400-mesh sieve.

[0034] S2. Mix bisphenol F epoxy resin with cashew phenol glycidyl ether and stir at 600 rpm for 10 min. Add half of the total mass of the composite solvent, then add the wetting and dispersing agent, KH560 modified zinc phosphate, aluminum tripolyphosphate, and composite UV stabilizer in sequence, and disperse at 900 rpm for 15 min to obtain the pre-wetting system.

[0035] S3. At 900 rpm, add aminated nano-silica and disperse for 15 min. Add anti-settling agent and disperse at 1800 rpm for 25 min. Grind to a fineness ≤20 μm, add the remaining composite solvent, stir at 600 rpm for 10 min, and pass through a 150-mesh sieve to obtain component A.

[0036] S4. After the substrate is treated to Sa2.5 grade, mix components A and B, mature for 15 minutes, spray to a dry film thickness of 100±10μm, and cure at room temperature for 7 days.

[0037] Example 2 The only difference between this embodiment and Example 1 is that the amount of bisphenol F epoxy is changed to 50 parts, the amount of cashew phenol glycidyl ether remains at 10 parts, the amount of composite solvent is adjusted accordingly, the stirring speed in S2 is 700 rpm, and the dispersion time is 13 min; the dispersion time in S3 is 16 min, the high-speed dispersion speed is 1700 rpm, and the time is 22 min, and all other conditions are the same.

[0038] Example 3 The only difference between this embodiment and Example 1 is that the amount of cashew phenol glycidyl ether is changed to 12 parts, the amount of bisphenol F epoxy is still 52 parts, the amount of composite solvent is adjusted accordingly, the stirring speed in S2 is 550 rpm, and the dispersion time is 14 min; the dispersion time in S3 is 20 min, the high-speed dispersion speed is 1900 rpm, and the time is 28 min, and all other conditions are the same.

[0039] Comparative Example 1 The only difference between this comparative example and Example 1 is that the KH560 modified zinc phosphate in the raw materials is replaced with an equal amount of micro-nano sheet zinc phosphate, and S1 is not used in the preparation process. All other conditions are the same.

[0040] Comparative Example 2 The only difference between this comparative example and Example 1 is that aminated nano-silica is not added, the amount of bisphenol F epoxy resin is increased to 56 parts, the amount of composite solvent is adjusted accordingly, and all other conditions are the same.

[0041] Comparative Example 3 The only difference between this comparative example and Example 1 is that aluminum tripolyphosphate is not added, the amount of bisphenol F epoxy resin is increased to 58 parts, the amount of composite solvent is adjusted accordingly, and all other conditions are the same.

[0042] Comparative Example 4 The only difference between this comparative example and Example 1 is that no composite UV stabilizer was added, the bisphenol F epoxy resin was increased to 52.6 parts, the amount of composite solvent was adjusted accordingly, and all other conditions were the same.

[0043] Comparative Example 5 The only difference between this comparative example and Example 1 is that after adding the anti-settling agent in S3, the mixture was stirred at 900 rpm for 10 minutes, without high-speed stirring at 1800 rpm. All other conditions were the same.

[0044] Comparative Example 6 The only difference between this comparative example and Example 1 is that the raw materials do not contain cashew phenol glycidyl ether, and the amount of bisphenol F epoxy resin is modified to 62 parts; all other conditions are the same.

[0045] Comparative Example 7 The only difference between this comparative example and Example 1 is that the raw materials do not contain bisphenol F epoxy resin, the amount of cashew phenol glycidyl ether is modified to 50 parts, the amount of composite solvent is adjusted accordingly, and all other conditions are the same.

[0046] Performance tests were conducted on the coatings formed from the paints of Examples 1-3 and Comparative Examples 1-7: Salt spray resistance refers to GB / T 1771-2024; neutral salt spray test refers to GB / T 10125-2021; UV yellowing resistance (color difference ΔE before and after exposure) refers to GB / T 23987.3-2025; pencil hardness refers to GB / 6739-2022; scratch corrosion propagation width refers to ISO 12944-6:2018; seawater immersion verification refers to NACE AMPP TM21612-2022.

[0047] The test results are shown in Table 1-2 and Figure 1-2 As shown.

[0048] Table 1 Results of salt spray resistance, neutral salt spray test, and UV yellowing resistance test

[0049] Table 2. Results of Pencil Hardness, Scratch Corrosion Spread Width, and Seawater Immersion Verification Tests

[0050] From Table 1-2 and Figure 1-2 It can be seen that Examples 1-3 showed no blistering or corrosion after 3000h of neutral salt spray testing, while the salt spray life of Comparative Examples 1-7 was significantly shortened: Comparative Example 1 (unmodified zinc phosphate) blistered after only 1800h, Comparative Example 2 (lacking nano-SiO2) blistered after only 2000h, Comparative Example 3 (lacking aluminum tripolyphosphate) blistered after only 2200h, Comparative Example 4 (lacking light stabilizer) blistered after 2800h, but still lower than the Examples, Comparative Example 5 (anti-settling agent not dispersed at high speed) blistered after only 1500h, Comparative Example 6 (without active diluent) blistered after only 1600h, and Comparative Example 7 (without epoxy resin) severely corroded after only 200h.

[0051] The reason for the above differences is that the micron-sized sheet-like KH560 modified zinc phosphate tends to be arranged parallel to the substrate during the coating curing process, forming a physical barrier layer and extending the diffusion path of water and chloride ions. At the same time, the aminated nano-silica fills the gaps between the micron-sized sheets, achieving a dense packing structure similar to sand and cement in concrete. This dual-scale synergy significantly reduces the porosity and oxygen permeability of the coating.

[0052] When trace amounts of moisture penetrate to the coating-metal interface, the two phosphates slowly release phosphate ions, which react with the steel substrate to form a dense iron phosphate complex protective film. Due to the different solubilities and release kinetics of the two phosphates, they can continuously provide passivating ions at different stages of the coating's service life, forming a gradient passivation effect that is more effective over time than a single zinc phosphate system.

[0053] The KH560-modified zinc phosphate surface has a silane cross-linked polymer layer, which can covalently bond with epoxy groups; the NH2 on the surface of the aminated nano-silica also undergoes ring-opening addition with epoxy groups. This dual anchoring effect enables the inorganic filler and organic resin to form a chemical bond, avoiding microcracks caused by interfacial debonding and further blocking the penetration channels of corrosive media.

[0054] The above data indicate that the silane modification of micron-sized sheet-like zinc phosphate, the physical framework of aminated nano-silica, the synergistic passivation of aluminum tripolyphosphate and zinc phosphate, the full component equivalent matching involving reactive diluents, and the high-speed activation process of anti-settling agents are all necessary conditions for achieving ultra-long salt spray resistance life. The absence of any one of these conditions will lead to a significant decrease in salt spray resistance performance.

[0055] The neutral salt spray test is mainly used in conjunction with the scratch corrosion propagation width test to observe the rust spread on both sides of the scratch after 1000 hours of exposure. In Examples 1-3, no rust spread was observed on both sides of the scratch, while in Comparative Examples 1, 2, 5, and 6, rust spread was obvious on both sides of the scratch, and in Comparative Example 7, the coating peeled off completely. This indicates that under simulated coating damage conditions, the coatings in the Examples can effectively inhibit corrosion from spreading from the scratch to the surrounding area. However, in the Comparative Examples, due to the lack of interfacial chemical anchoring (unmodified zinc phosphate), micro-nano dual-scale dense stacking (lack of nano-SiO2), full component equivalent matching (no diluent), or dense curing structure (anti-settling agent not activated), the scratch became a channel for rapid penetration of the corrosive medium, leading to rapid rust spread.

[0056] The scratch corrosion propagation width of Examples 1-3 was 1.7-1.9 mm, significantly lower than that of Comparative Examples 1-7. This result is attributed to the synergistic protective mechanism of physical barrier and chemical passivation in the Examples. The dense structure constructed by aminated nano-silica and modified zinc phosphate can block the lateral diffusion of corrosive media within the coating. Simultaneously, bisphosphate rapidly forms a recalcitrant passivation film at the scratch site, effectively inhibiting corrosion propagation. In contrast, the Comparative Examples, lacking key components such as modified filler, nano-silica, and the dual passivation system, or exhibiting dispersion or cross-linking defects, suffered from the failure of physical barrier and chemical passivation capabilities after coating damage. Corrosion rapidly propagated along the weak interfaces of the coating, leading to a significant increase in scratch propagation width and protection failure.

[0057] The ΔE values ​​of Examples 1-3 were 1.1-1.3, with no obvious yellowing; the ΔE of Comparative Example 4 (without UV stabilizer) was 4.2, with obvious yellowing visible to the naked eye and slight powdering on the surface. Other comparative examples, because their formulations still contained composite UV stabilizers, maintained a ΔE of 1.3-1.5.

[0058] This indicates that the unsaturated long chains in the cashew phenol homologous system (cashew phenol glycidyl ether + cashew phenol modified amine) are prone to photo-oxidative degradation under ultraviolet irradiation. The addition of the composite ultraviolet light stabilizer (Tinuvin 1130 + Tinuvin 292) can effectively inhibit this process. For anti-corrosion coatings applied in marine atmospheric areas (ship decks, superstructures, etc.), weather resistance is a key indicator to ensure the long-term service of the coating. The lack of a light stabilizer will lead to premature yellowing and chalking of the coating, resulting in loss of protective function.

[0059] The pencils of Examples 1-3 have a hardness of 3H, which is better than the comparative examples: Comparative Examples 1-4 and Comparative Example 6 are 2H, Comparative Example 5 is H, and Comparative Example 7 is 2B (the coating is extremely soft).

[0060] The difference in hardness reflects the difference in crosslinking density and compactness of the coating: Examples 1-3 have high hardness due to the high crosslinking density and low internal stress network structure formed by the full component equivalent matching (both the main resin and the diluent epoxy participate in crosslinking) and the dense stacking of micro-nano dual-scale fillers; Comparative Example 6 has a hardness of 2H due to the lack of active diluent leading to a reduction in crosslinking points; Comparative Example 5 has a hardness of H due to the presence of micro-defects in the coating film caused by the unactivated anti-settling agent; Comparative Example 7, with cashew phenol glycidyl ether as the main film-forming material (mono-epoxy functional group), cannot form an effective crosslinking network, and the coating is extremely soft (2B), completely lacking the mechanical strength requirements of an anti-corrosion coating.

[0061] Examples 1-3, after immersion in artificial seawater (pH=7.8-8.2, salinity 3.5%) for 12 weeks, showed adhesion retention rates of 91%, 89%, and 90%, respectively, with intact coating appearance. Comparative Examples 1-6 showed adhesion retention rates of 51%-86%, with the vast majority lower than the examples. Specifically, Comparative Example 1 (unmodified zinc phosphate) had a retention rate of only 67%, Comparative Example 5 (anti-settling agent not rapidly dispersed) only 58%, and Comparative Example 6 (no active diluent) only 64%, all significantly lower than the examples.

[0062] The reason for the above differences is that the micro-nano dual-scale dense shielding layer effectively prevents Cl from... - Mg 2+ SO4 2- Corrosive ions penetrate to the interface; the bisphosphate passivation film is chemically stable in weakly alkaline seawater and continuously and slowly releases phosphate ions to repair micro-defects; high initial adhesion makes it difficult for water molecules to wedge into the interface. Comparative Example 1, due to a weak interface, allowed water molecules to easily penetrate, resulting in a retention rate of only 67%; Comparative Example 2, due to an incomplete shielding layer, allowed seawater to penetrate to the interface, resulting in a retention rate of 72%; Comparative Example 3, due to localized failure of the passivation layer during long-term immersion, resulted in a retention rate of 76%; Comparative Example 4, due to the continued effectiveness of other synergies, achieved a retention rate of 86%, still higher than the other comparative examples; Comparative Example 5, due to macroscopic defects in the coating, allowed rapid seawater penetration, resulting in a retention rate of only 58%; Comparative Example 6, due to brittle cross-linked networks and micro-cracks at the interface, resulted in a retention rate of 64%; Comparative Example 7, due to complete coating failure, could not be measured. Seawater immersion verified the long-term stability of the coating in the fully immersed zone, providing crucial evidence for the coating's suitability for ship hulls.

[0063] Therefore, this invention employs the aforementioned micro / nano anti-corrosion coating and its preparation method. Through a synergistic mechanism integrating full-component equivalent matching, bivalent interface anchoring, bisphosphate gradient passivation, and UV stabilization, it achieves ultra-long salt spray resistance, significant self-inhibition of corrosion propagation after scratches, ultra-high interfacial bonding strength with metal substrates, and UV yellowing resistance that overcomes the weather resistance bottleneck of the cashew phenol system. Simultaneously, it possesses excellent industrial practicality and economy, providing a high-performance, low-cost, and easily manufactured overall solution for long-term corrosion protection of zinc-free epoxy primers in all marine environments.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A micro / nano anti-corrosion coating, characterized in that: The product comprises two components, A and B. By mass, component A includes 45-60 parts of bisphenol F epoxy resin, 8-15 parts of cashew phenol glycidyl ether, 10-15 parts of KH560 modified zinc phosphate, 2-5 parts of aminated nano silica, 4-8 parts of aluminum tripolyphosphate, 0.3-0.8 parts of wetting and dispersing agent, 0.5-1.2 parts of anti-settling agent, and 0.3-0.6 parts of composite UV stabilizer, with the composite solvent to make up the balance to 100 parts. Component B includes 100 parts of cashew phenol modified amine curing agent.

2. The micro / nano anti-corrosion coating according to claim 1, characterized in that: The ratio of the total amount of epoxy groups of bisphenol F epoxy resin and the total amount of epoxy groups of cashew phenol glycidyl ether in component A to the amount of amine groups in component B is 1:(0.95-1.05).

3. The micro / nano anti-corrosion coating according to claim 1, characterized in that: The epoxy equivalent of bisphenol F type epoxy resin is 155-185 g / eq, the epoxy value of cashew phenol glycidyl ether is 0.2-0.28 eq / 100g, the coating rate of KH560 modified zinc phosphate is 1.5-2.5%, the flake diameter is 2-5 μm, the composite UV stabilizer is Tinuvin 1130 and Tinuvin 292 in a mass ratio of 2:1, and the composite solvent is butyl acetate mixed with xylene and PMA in a volume ratio of 3:4:

1.

4. The method for preparing a micro / nano anti-corrosion coating as described in any one of claims 1-3, characterized in that: Includes the following steps: S1. Preparation of KH560 modified zinc phosphate: Add micro-nano sheet zinc phosphate to a high-speed mixer, heat up, dilute KH560 with ethanol to a concentration of 50%, adjust the pH with glacial acetic acid, spray 2.0% of the micro-nano sheet zinc phosphate dilution into the micro-nano sheet zinc phosphate while stirring, continue stirring for 30 min, discharge, vacuum dry, and sieve to obtain KH560 modified zinc phosphate; S2. Mix bisphenol F epoxy resin with cashew phenol glycidyl ether, stir at low speed, then add half of the total mass of composite solvent, and then add wetting and dispersing agent, KH560 modified zinc phosphate and aluminum tripolyphosphate in sequence, and stir at medium speed to disperse to obtain a pre-wetting system. S3. While maintaining the rotation speed, add aminated nano-silica to the pre-wetting system obtained in S2 and continue to disperse. After dispersion, add an anti-settling agent and stir at high speed to disperse. After dispersion, a slurry is obtained. Grind the slurry and add the remaining composite solvent. Stir at low speed and sieve to obtain component A. S4. After substrate treatment, mix component A and component B to obtain coating. After the coating has cured, spray the coating onto the substrate surface.

5. The method for preparing a micro / nano anti-corrosion coating according to claim 4, characterized in that: In S1, the temperature is raised to 80-100℃, the pH is adjusted to 5-6, the vacuum drying temperature is 80℃, the vacuum drying time is 2 hours, and then it is passed through a 400-mesh sieve.

6. The method for preparing a micro / nano anti-corrosion coating according to claim 4, characterized in that: In S2, the low-speed stirring speed is 500-800 rpm and the low-speed stirring time is 10-15 min; the medium-speed stirring speed is 800-1000 rpm and the medium-speed stirring time is 10-15 min.

7. The method for preparing a micro / nano anti-corrosion coating according to claim 4, characterized in that: In S3, the high-speed stirring speed is 1500-2000 rpm, the high-speed stirring time is 20-30 min, and the slurry is ground to a fineness of ≤20μm.

8. The method for preparing a micro / nano anti-corrosion coating according to claim 4, characterized in that: In S3, the low-speed stirring time is 10-15 minutes, and the mixture is passed through a 150-mesh sieve.

9. The method for preparing a micro / nano anti-corrosion coating according to claim 4, characterized in that: In S4, the maturation time is 10-15 minutes.

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