An ultra-heavy-duty anticorrosive coating capable of being applied with oil and a preparation method thereof

Abstract

This invention discloses an ultra-heavyweight anti-corrosion coating that can be applied with oil and its preparation method. The coating is a two-component system. Component A comprises fluorosilicone-modified polyacrylate-phosphate-catechol terpolymer (FSPPC), hydrogenated bisphenol A epoxy resin, polyaspartic acid ester resin, fluorinated graphene, aluminum tripolyphosphate, nano-zinc oxide, and fumed silica; component B comprises polyetheramine, alicyclic amine, modified mercaptoacetate, melamine polyphosphate, aluminum hydroxide, and dibutyltin dilaurate; the weight ratio of components A to B is 100:25-35. The low surface energy fluorosilicone segments in the FSPPC molecules can actively insert into the interface between the oil film and the metal, driving the oil to migrate outwards. Subsequently, the phosphate and catechol groups are exposed and form chemical bonds with the metal oxide, achieving molecular-level replacement and interfacial chelation anchoring of the oil film. This invention's coating can be applied with an oil content not exceeding 500 g / m³. 2 It can be directly coated on metal surfaces without the need for degreasing, rust removal, or drying pretreatment.

Description

Technical Field

[0001] This invention relates to the field of heavy-duty anti-corrosion coatings, specifically to an ultra-heavy-duty anti-corrosion coating that can be applied with oil and its preparation method. Background Technology

[0002] Heavy-duty anti-corrosion coatings are widely used in industrial fields such as petrochemicals, shipbuilding and marine engineering, municipal pipelines, and ports to protect metal components that are exposed to corrosive environments for extended periods. In actual engineering maintenance scenarios, the surfaces of metal equipment and pipelines are often contaminated with grease-like pollutants such as lubricating oil, rust-preventive oil, and crude oil, a phenomenon that is difficult to avoid during the long-term operation of industrial facilities.

[0003] Currently, surface treatment before coating application is a crucial step in heavy-duty anti-corrosion coating projects. Conventional construction specifications require metal substrates to undergo pretreatment processes such as degreasing, rust removal, and sanding before coating to ensure an effective adhesion interface between the paint and the substrate. For surfaces contaminated with grease, solvent cleaning, alkaline degreasing, or sandblasting are typically required to remove the oil film before application. While these pretreatment processes generally meet the quality requirements, in certain specific situations, such as non-stop maintenance of in-service equipment, operations in confined spaces, or underwater or humid environments, complete degreasing is more challenging and increases construction costs accordingly.

[0004] For coating applications on oily surfaces, some existing technologies have been explored. Some modified epoxy coatings improve wettability on oily surfaces by introducing polar groups, achieving some adhesion on surfaces with low oil content. However, as the oil content increases, the interfacial bonding between the coating and the substrate decreases significantly, leading to interfacial delamination and affecting corrosion resistance. Furthermore, a class of polyurethane-modified epoxy adhesives for oily surfaces exists, exhibiting some adhesion ability, but these products primarily provide point-like adhesion, making it difficult to form a continuous and uniform protective film, resulting in relatively limited corrosion protection. Titanium chelate coatings utilize metal chelation mechanisms to enhance adhesion, showing good corrosion protection on clean metal surfaces. However, their chelation reaction depends on direct contact with the exposed metal surface; when an oil film covers the surface, the chelation efficiency is significantly affected.

[0005] From an interfacial chemistry perspective, the adsorption film formed by oily contaminants on metal surfaces significantly reduces the wetting ability of coatings on the substrate and hinders the formation of chemical bonds between the coating resin and the metal oxide. This is the core interfacial problem faced by oil-based coating technology. Existing solutions mainly focus on two directions: one is to emulsify and disperse the oil using surfactants, then remove the oil film with water washing; the other is to improve the coating system's penetration ability to the oil film, allowing active groups to contact the metal surface as much as possible. The former requires additional cleaning steps, while the latter's effectiveness is limited by the oil film thickness and the type of oil, especially in cases of heavy oil contamination (oil content exceeding 100 g / m³). 2 Ensuring adhesion under these conditions still presents certain challenges.

[0006] Therefore, developing a coating system that can be directly applied to metal surfaces with high oil content while also possessing excellent long-lasting anti-corrosion performance is of practical significance for reducing industrial maintenance costs and expanding the application scenarios of heavy-duty anti-corrosion coatings. Summary of the Invention

[0007] Based on the problems existing in the background technology, the present invention provides a method that can be applied to oil content not exceeding 500g / m 2 A two-component coating and its matching construction method that can be directly applied to oily metal surfaces without any degreasing pretreatment, while achieving a heavy-duty anti-corrosion rating.

[0008] This invention is implemented through the following technical solutions: This invention provides an ultra-heavy-duty anti-corrosion coating that can be applied with oil. It is a two-component system, including component A and component B.

[0009] Component A comprises the following components by weight: 8-12 parts of fluorosilicone modified polyacrylate-phosphate-catechol terpolymer (FSPPC), 20-25 parts of hydrogenated bisphenol A epoxy resin, 10-15 parts of polyaspartic acid ester resin, 0.5-1.0 parts of fluorinated graphene, 3-5 parts of aluminum tripolyphosphate, 4-6 parts of nano zinc oxide, 2-3 parts of fumed silica, and 35-55 parts of mixed solvent.

[0010] Component B comprises the following components by weight: 40-50 parts of polyetheramine, 20-30 parts of alicyclic amine, 8-12 parts of hydroxyethyl methacrylate modified mercaptoacetate, 5-8 parts of melamine polyphosphate, 5-10 parts of aluminum hydroxide, 0.3-0.8 parts of dibutyltin dilaurate, and 2-10 parts of mixed solvent.

[0011] The weight ratio of component A to component B is 100:25-35.

[0012] Furthermore, the fluorosilicone-modified polyacrylate-phosphate-catechin terpolymer is prepared through the following steps: Step 1: Trimethylolpropane was reacted with 2-bromoisobutyryl bromide under pyridine catalysis to prepare the dibromo-ATRP initiator precursor TMP-Br2; Step 2: After reacting TMP-Br2 with trichlorophosphate, deionized water is added for hydrolysis to obtain the phosphate ester-functionalized dibromoATRP initiator TMP-PO(OH)2-Br2. Step 3: Using TMP-PO(OH)2-Br2 as an initiator and CuBr / PMDETA as a catalytic system, ATRP polymerization was carried out with trifluoroethyl methacrylate and methacryloxypropyltrimethoxysilane as mixed monomers to obtain polymer intermediates. Step 4: After azidation of the terminal bromine atoms of the polymer intermediate, it undergoes a CuAAC click chemical reaction with N-propynyl maleimide to obtain a polymer containing maleimide end groups. Step 5: The polymer containing maleimide end groups is reacted with dopamine hydrochloride in phosphate buffer, purified by dialysis, and then freeze-dried to obtain the fluorosilicone modified polyacrylate-phosphate-catechin terpolymer.

[0013] Further, in the first step, the molar ratio of trimethylolpropane to 2-bromoisobutyryl bromide is 1:2.0, the reaction temperature is 0-25℃, and the reaction time is 12h; in the second step, the molar ratio of trichlorophosphate to the hydroxyl group contained in TMP-Br2 is 1:1.05-1.15, the reaction temperature is 0-5℃, the molar ratio of deionized water to trichlorophosphate is 10-15:1, and the hydrolysis is carried out at room temperature for 4-6h.

[0014] Furthermore, in the third step, the molar ratio of CuBr to initiator is 1:1, the molar ratio of PMDETA to CuBr is 1:1, the molar ratio of mixed monomers is 2:1, the molar ratio of mixed monomers to initiator is 15-20:1, the polymerization temperature is 60±2℃, and the polymerization time is 6-8h.

[0015] Further, in the fourth step, the molar ratio of sodium azide to terminal bromine atoms is 3:1, and the substitution reaction is carried out in DMF at 60℃ for 12 h; the molar ratio of CuSO4·5H2O to azide groups is 0.1:1, and the click chemistry reaction is carried out at room temperature for 6-8 h; in the fifth step, the pH of the phosphate buffer is 8.0-8.5, the reaction temperature is 30±2℃, the molar ratio of dopamine hydrochloride to maleimide groups is 1.2:1, the reaction time is 12-16 h, the dialysis molecular weight cutoff (MWCO) is 1000, and the dialysis time is 48 h.

[0016] Further, the mixed solvent is a mixture of xylene and n-butanol in a weight ratio of 7:3; the alicyclic amine is isophorone diamine; the polyether amine is polyether amine D-2000; the hydroxyethyl methacrylate-modified thioglycolate is prepared by transesterification of thioglycolate and hydroxyethyl methacrylate, with a number average molecular weight of 300-500, and the molecular structure simultaneously containing thiol, ester, and acrylate double bonds, with a thiol content of 8-10 wt%; the hydroxyethyl methacrylate-modified thioglycolate is prepared by transesterification: thioglycolate and hydroxyethyl methacrylate are fed in a certain molar ratio, catalyzed by an acidic catalyst, and transesterified under heating and reduced pressure in the presence of a polymerization inhibitor, and the byproducts are removed by vacuum distillation to obtain the hydroxyethyl methacrylate-modified thioglycolate.

[0017] Further, the preparation method of the hydroxyethyl methacrylate modified mercaptoacetate includes the following steps: mercaptoacetate and hydroxyethyl methacrylate are fed in a molar ratio of 1:(1-1.5), p-toluenesulfonic acid is used as a catalyst (0.5-1.0 wt% of the total mass of raw materials), hydroquinone is added as a polymerization inhibitor (0.01-0.02 wt% of the total mass of raw materials), and the reaction is carried out at 60-80℃ under reduced pressure (2-5 kPa absolute pressure) for 4-6 h. The byproduct methanol is removed by reduced pressure distillation to obtain the hydroxyethyl methacrylate modified mercaptoacetate with a number average molecular weight of 300-500 and a mercapto content of 8-10 wt%.

[0018] The second aspect of this invention discloses a method for preparing the ultra-heavy-duty anti-corrosion coating, comprising the following steps: Step 1: According to the weight parts of component A, add each component to the mixed solvent in sequence, and stir and disperse at 500-800 rpm for 1-2 hours to obtain component A; Step 2: According to the weight parts of component B, add each component to the mixed solvent in sequence, and stir and mix at 300-500 rpm for 0.5-1 h to obtain component B; Step 3: Before use, mix component A and component B at a weight ratio of 100:25-35, stir for 5-10 minutes, and let stand for 10-15 minutes to obtain the ultra-heavy anti-corrosion coating.

[0019] A third aspect of the present invention also discloses a method for applying the aforementioned heavy-duty anti-corrosion coating to an oil-contaminated metal surface, comprising the following steps: Step 1: Provide oil content ≤500g / m 2 For metal substrates with rust content <100μm, there is no need to perform degreasing, rust removal, or drying treatment on the metal substrate; Step 2: Mix component A and component B at a weight ratio of 100:25-35 until homogeneous, and directly coat the mixture onto the surface of the metal substrate. The dry film thickness is 180-220 μm. Step 3: Curing the coating at 15-50℃ and relative humidity ≤85% according to a staged curing process to form a protective coating.

[0020] Furthermore, the staged curing process specifically includes: The first stage involves curing at 15–25°C and 50–70% relative humidity for 6–12 hours, primarily through epoxy-amine addition reactions to form a cross-linked network framework. The second stage involves curing at 25–40°C and 60–80% relative humidity for 12–24 hours, promoting the hydrolysis and condensation of siloxane groups to fill micropores and form an organic-inorganic interpenetrating network. The third stage involves post-curing at ambient temperature and relative humidity less than 85% for 24–48 hours, ensuring the synergistic completion of the three curing reactions under the catalysis of dibutyltin dilaurate, thus avoiding stress concentration.

[0021] Furthermore, in step two, the coating method is one of brushing, rolling, or airless spraying; when using airless spraying, the spraying pressure is 15-20MPa, the nozzle diameter is 0.43-0.53mm, and the spraying distance is 30-40cm.

[0022] The beneficial effects of this invention are: This invention designs an amphiphilic chelation-oil film replacement mechanism, achieving molecular-level oil film replacement through the ternary synergistic effect of FSPPC. The oil film replacement completion time is ≤8h, at 500g / m³. 2 The coating adhesion on high-oil-content metal surfaces remains ≥5.8MPa, far exceeding the adhesion levels of existing technologies. The low-surface-energy fluorosilicone segments in FSPPC molecules can actively insert into the interface between the oil film and the metal, driving the grease to migrate outwards. Subsequently, the phosphate ester and catechol groups are exposed and form chemical bonds with the metal oxides, completely displacing the grease from the interface. This mechanism is fundamentally different from the traditional surfactant emulsification degreasing route, enabling the coating to achieve true chemical bonding with oily metal surfaces without any degreasing pretreatment, fundamentally overcoming the technical bottleneck of insufficient adhesion in oily coatings.

[0023] The FSPPC molecule of this invention simultaneously carries two types of strong chelating groups: phosphate ester groups and catechol groups. These two groups have complementary mechanisms of action and independent binding sites, jointly anchoring at the metal interface to form a multi-point, high-density chelating structure. The composite anti-rust system composed of fluorinated graphene and aluminum tripolyphosphate further achieves a synergistic effect of physical barrier and active chemical corrosion protection. The former blocks the penetration of corrosive media through a layered, oriented arrangement, while the latter generates an in-situ iron phosphate protective film. The superposition of these multiple protective mechanisms enables the coating to achieve a corrosion resistance of 500 g / m³.2 The coating has a neutral salt spray resistance time of over 12,500 hours (up to 15,200 hours) on oil-containing metal surfaces and a crude oil immersion time of over 4,600 hours at 60°C. The overall anti-corrosion performance of the coating on oil-stained metal surfaces reaches the super-heavy-duty anti-corrosion level.

[0024] This invention addresses the significant differences in the curing reaction rates among three types of curing reactions in coating systems: epoxy-amine addition, mercapto-epoxy ring-opening, and siloxane hydrolysis-condensation. A staged curing process is designed to address this issue. The three curing stages sequentially aim to establish the framework, fill micropores, and then cure, ensuring the orderly and synergistic progression of each reaction. This fundamentally avoids the internal stress concentration and coating defects caused by rate mismatch in multi-component curing systems, ultimately forming a uniform and dense organic-inorganic interpenetrating network protective coating. Furthermore, the coating of this invention can be directly applied under complex conditions such as oil, rust, and moisture, eliminating the need for pretreatment processes such as sandblasting, rust removal, and solvent wiping. This significantly reduces overall construction costs and broadens the scope of engineering applications. Detailed Implementation

[0025] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0026] Example 1: Preparation of an ultra-heavy-duty anti-corrosion coating that can be applied with oil.

[0027] The preparation of FSPPC includes the following steps: Step 1: Dissolve trimethylolpropane (TMP) in anhydrous dichloromethane, cool to 0°C in an ice bath, and slowly add a mixture of 2-bromoisobutyryl bromide and pyridine dropwise. The molar ratio of TMP to 2-bromoisobutyryl bromide is 1:2.0, and the pyridine and 2-bromoisobutyryl bromide are equimolar. After the addition is complete, the mixture is brought to room temperature and reacted for 12 h. The reaction solution is washed successively with dilute hydrochloric acid, saturated sodium bicarbonate solution, and deionized water. After drying the organic phase, the solvent is removed by vacuum distillation to obtain TMP-Br2, with a yield of approximately 85%.

[0028] Step 2: Dissolve TMP-Br2 in anhydrous diethyl ether, cool in an ice bath to 0–5°C, and slowly add trichlorophosphate dropwise. The molar ratio of trichlorophosphate to the hydroxyl groups in TMP-Br2 is 1:1.1. Continue the reaction at 0–5°C for 2 h, then add deionized water (molar ratio of deionized water to trichlorophosphate is 12:1), and raise the temperature to room temperature with stirring for 5 h of hydrolysis. After extraction, drying, and vacuum distillation, TMP-PO(OH)2-Br2 is obtained, with a yield of approximately 78%.

[0029] Step 3: Using TMP-PO(OH)2-Br2 as the initiator and CuBr / PMDETA as the catalytic system (CuBr to initiator molar ratio 1:1, PMDETA to CuBr molar ratio 1:1), a mixed monomer mixture of trifluoroethyl methacrylate (TFEMA) and methacryloxypropyltrimethoxysilane (MAPTMS) was added (TFEMA to MAPTMS molar ratio 2:1, mixed monomer to initiator molar ratio 20:1). After degassing, the system was protected under nitrogen and reacted at 60℃ for 6 h. The copper salt was removed by passing the solution through a neutral alumina column, and the precipitate was purified and dried under vacuum to obtain a polymer intermediate with a weight-average molecular weight of approximately 2800, PDI = 1.15, and a yield of approximately 72%.

[0030] Step 4: The polymer intermediate was dissolved in anhydrous DMF, and sodium azide was added at a molar ratio of 3:1 to the terminal bromine atoms. The reaction was carried out at 60°C for 12 h to completely convert the terminal bromine atoms to azide groups. Subsequently, N-propynylmaleimide (equimolar with the azide groups), CuSO4·5H2O (molar ratio of 0.1:1 with the azide groups), and sodium ascorbate (molar ratio of 2:1 with CuSO4) were added, and CuAAC click chemistry was carried out at room temperature for 6 h. The reaction solution was purified by dialysis (MWCO 1000, 48 h) and freeze-dried to obtain the polymer containing maleimide end groups, with a yield of approximately 65%.

[0031] Step 5: The polymer containing maleimide end groups was dissolved in a phosphate buffer solution with a concentration of 0.1 mol / L and a NaCl concentration of 0.15 mol / L. The pH was adjusted to 8.3, and dopamine hydrochloride was added at a molar ratio of 1.2:1 to maleimide groups. The reaction was carried out at 30°C in the dark for 12 h. The reaction solution was purified by dialyzing (MWCO 1000, 48 h), and then freeze-dried to obtain FSPPC with a weight-average molecular weight of approximately 3800, a PDI of 1.18, and a yield of approximately 80%.

[0032] The specific steps involved in coating preparation include: Component A: FSPPC (10 parts), hydrogenated bisphenol A epoxy resin (22 parts), polyaspartic acid ester resin (12 parts), fluorinated graphene (0.8 parts), aluminum tripolyphosphate (4 parts), nano zinc oxide (5 parts), and fumed silica (2.5 parts) were sequentially added to a mixed solvent (44 parts) composed of xylene and n-butanol (weight ratio 7:3). The mixture was stirred and dispersed at 700 rpm for 1.5 h to obtain Component A.

[0033] Component B: Polyetheramine D-2000 (45 parts), isophorone diamine (25 parts), hydroxyethyl methacrylate modified mercaptoacetate (10 parts, number average molecular weight 400, mercapto content 9 wt%), melamine polyphosphate (6 parts), aluminum hydroxide (8 parts), and dibutyltin dilaurate (0.5 parts) were added sequentially to a mixed solvent (6 parts) and stirred at 400 rpm for 0.5 h to obtain component B.

[0034] Before use, mix component A and component B at a weight ratio of 100:30, stir for 8 minutes, and let stand for 12 minutes to mature, thus obtaining the coating.

[0035] Coating and curing: Spray the surface of the Q235 steel plate (100 mm × 150 mm × 3 mm) with anti-rust oil until the oil content is 200 g / m². 2 No surface pretreatment is required; the above coating is applied directly by brushing, with a dry film thickness of 200±10 μm. Curing is performed using a phased curing process: Phase 1: Curing at 20℃ and 60% relative humidity for 6 hours; Phase 2: Curing at 35℃ and 70% relative humidity for 12 hours; Phase 3: Curing at room temperature and 75% relative humidity for 30 hours.

[0036] Example 2: Preparation of an ultra-heavy anti-corrosion coating that can be applied with oil.

[0037] The preparation method of FSPPC is the same as in Example 1, except that: in the first step, the molar ratio of TMP to 2-bromoisobutyryl bromide is 1:2.0; in the third step, the molar ratio of mixed monomers to initiator is adjusted to 15:1, and the polymerization time is adjusted to 8 h. The resulting intermediate polymer has a weight-average molecular weight of 2600 and a PDI of 1.18; the conditions of the remaining steps remain unchanged. The resulting FSPPC has a weight-average molecular weight of 3500 and a PDI of 1.19.

[0038] The specific steps involved in coating preparation include: Component A: FSPPC (8 parts), hydrogenated bisphenol A epoxy resin (25 parts), polyaspartic acid ester resin (10 parts), fluorinated graphene (0.5 parts), aluminum tripolyphosphate (5 parts), nano zinc oxide (4 parts), fumed silica (3 parts), and mixed solvent (45 parts) were stirred and dispersed at 600 rpm for 2 h.

[0039] Component B: Polyetheramine D-2000 (50 parts), isophorone diamine (20 parts), hydroxyethyl methacrylate modified mercaptoacetate (12 parts, number average molecular weight 300, mercapto content 10 wt%), melamine polyphosphate (5 parts), aluminum hydroxide (10 parts), dibutyltin dilaurate (0.3 parts), and mixed solvent (3 parts). Stir and mix at 300 rpm for 1 h.

[0040] The weight ratio of component A to component B is 100:25. After stirring for 8 minutes, let it stand for 12 minutes to mature before use.

[0041] Coating and curing: The test substrate was the same as in Example 1, with an oil content of 200 g / m³. 2 Airless spraying was used, with a spraying pressure of 18 MPa, a nozzle diameter of 0.48 mm, a spraying distance of 35 cm, and a dry film thickness of 190±10 μm. The curing process was the same as in Example 1.

[0042] Example 3: This embodiment verifies the coating performance under conditions of high oil content (400 g / m²).

[0043] The preparation method of FSPPC is the same as in Example 1, except that the molar ratio of TMP to 2-bromoisobutyryl bromide in the first step is 1:2.0; the resulting FSPPC has a weight-average molecular weight of 3800 and PDI=1.18.

[0044] The specific steps involved in coating preparation include: Component A: FSPPC (12 parts), hydrogenated bisphenol A epoxy resin (20 parts), polyaspartic acid ester resin (15 parts), fluorinated graphene (1.0 part), aluminum tripolyphosphate (3 parts), nano zinc oxide (6 parts), fumed silica (2 parts), and mixed solvent (41 parts) were stirred and dispersed at 800 rpm for 1 h.

[0045] Component B: Polyetheramine D-2000 (40 parts), isophorone diamine (30 parts), hydroxyethyl methacrylate modified mercaptoacetate (8 parts, number average molecular weight 500, mercapto content 8 wt%), melamine polyphosphate (8 parts), aluminum hydroxide (5 parts), dibutyltin dilaurate (0.8 parts), and mixed solvent (8 parts). Stir and mix at 500 rpm for 0.5 h.

[0046] The weight ratio of component A to component B is 100:35. After stirring for 8 minutes, let it stand for 12 minutes to mature before use.

[0047] Coating and curing: Spray the surface of Q235 steel plate with anti-rust oil until the oil content is 400 g / m². 2 No pretreatment is required; it is applied by brushing, with a dry film thickness of 210±10 μm. The curing process is the same as in Example 1.

[0048] Comparative Example 1: The coating formulation was based on Example 1, except that FSPPC was not added to component A. All parts of FSPPC were replaced with an equal amount of hydrogenated bisphenol A epoxy resin (i.e., the amount of hydrogenated bisphenol A epoxy resin was increased to 32 parts). The remaining components and amounts were the same as in Example 1, and the coating method was the same. Due to the lack of the interfacial displacement function of FSPPC, the oil film hindered the curing reaction rate, resulting in a decrease. The curing process adopted the same staged curing conditions as in Example 1, but the time of each stage was extended accordingly: the first stage was cured at 20°C and 60% relative humidity for 12 h; the second stage was cured at 35°C and 70% relative humidity for 24 h; and the third stage was cured at room temperature and 75% relative humidity for 36 h.

[0049] Comparative Example 2: The coating formulation was based on Example 1, except that in component A, 10 parts of FSPPC were replaced with an equal amount of a commercially available ordinary fluorosilicone polymer (linear structure, molecular weight of approximately 15,000, fluorosilicone segment content of approximately 40%, and free of phosphate ester and catechol groups). The remaining components and amounts were the same as in Example 1, and the coating method was the same. Due to the insufficient chelation ability of ordinary fluorosilicone polymer with the metal interface, the curing process was slow under oil surface conditions. The curing process adopted the same staged curing conditions as in Example 1, with the time of each stage appropriately extended: the first stage was cured at 20°C and 60% relative humidity for 10 h; the second stage was cured at 35°C and 70% relative humidity for 20 h; and the third stage was cured at room temperature and 75% relative humidity for 30 h.

[0050] Comparative Example 3: The coating formulation is based on Example 1, except that the polyaspartic acid ester resin in component A is removed and replaced with an equal amount of hydrogenated bisphenol A epoxy resin. Single hydrogenated bisphenol A epoxy resin is used as the film-forming base material, and the rest of the formulation and process are the same as in Example 1.

[0051] Comparative Example 4: The coating formulation is based on Example 1. Fluorinated graphene is not added to component A, and its part is supplemented by an equal amount of aluminum tripolyphosphate (i.e., the total amount of aluminum tripolyphosphate is 4.8 parts). The other components and their amounts, coating and curing processes are the same as in Example 1.

[0052] Comparative Example 5: The coating formulation is the same as in Example 1, and the coating substrate and construction method are the same as in Example 1. However, the curing process is changed to be cured in one step at a constant temperature of 25°C and a relative humidity of 60% throughout the process, without staged temperature increases. The total curing time is 72 hours, and the other conditions remain unchanged.

[0053] Performance testing: The test methods and standards used for coated oil-impregnated Q235 steel plates in the above embodiments and comparative examples are as follows: Oil adhesion was tested according to the pull-off method in GB / T 5210-2006, with a failure criterion of adhesion below 3 MPa; neutral salt spray resistance was tested according to GB / T 1771-2007, 5% NaCl solution, 35±2℃, with failure defined as the appearance of rust spots at the scribing point or adhesion below 3 MPa; crude oil immersion resistance was tested according to Method A in GB / T 9274-1988, temperature 60℃, with failure defined as bubbling or peeling; complete curing time was measured as actual drying time. Oil film replacement completion time: The metal-coating interface was observed using a laser confocal microscope, with an interface grease residue rate of <5% as the criterion for oil film replacement completion. The replacement completion time for each group was tested according to this method. Specific test results are shown in Table 1.

[0054] Table 1 Performance test results of the examples and comparative examples

[0055] As shown in Table 1, the embodiments of the present invention are significantly superior to the comparative examples in terms of adhesion to oily surfaces, salt spray life, and resistance to crude oil immersion. This fully verifies the indispensability and synergistic effect of the three core technologies: FSPPC terpolymer, composite anti-rust system, and staged curing process. Compared with Example 1, the coating in Comparative Example 1 without FSPPC showed an adhesion of only 1.2 MPa on oily surfaces, with obvious interfacial peeling. Its salt spray life decreased to 850 h, less than 6% of Example 1, failing to meet the requirements for heavy-duty corrosion protection. This proves that FSPPC is a key functional component for achieving oily coating, and ordinary epoxy resin cannot replace its oil film replacement and chemical chelation functions. Although the coating in Comparative Example 2 using ordinary fluorosilicone polymers improved oil surface wettability to some extent due to the presence of oleophobic segments, the lack of synergistic chelation of phosphate ester groups and catechol groups resulted in an adhesion of only 2.8 MPa, an oil film replacement time extended to 18 h, and a salt spray life only 23% of Example 1. The results show that the ternary synergy of the three functional groups (fluorosilicone segments, phosphate ester groups, and catechol groups) in FSPPC is a necessary condition for achieving high-performance oil-resistant coating; simply introducing fluorosilicone segments cannot achieve the technical effect of this invention. In Comparative Example 3, after removing the polyaspartic acid ester resin, the coating flexibility decreased, and cohesive and interfacial mixing damage occurred. The adhesion dropped to 4.1 MPa, and the salt spray resistance decreased to 8200 h, proving that the toughening effect of the composite base system makes a significant contribution to the coating integrity. In Comparative Example 4, after removing fluorinated graphene, the neutral salt spray resistance life decreased to 9800 h, which is 64% of that in Example 1, and the crude oil immersion time decreased to 3000 h. The results show that the layered directional barrier effect of fluorinated graphene significantly contributes to the long-term anti-corrosion performance of the coating, and there is a significant synergistic effect with the composite anti-rust system composed of aluminum tripolyphosphate. A single anti-rust pigment cannot achieve the anti-corrosion performance level of this invention. In Comparative Example 5, the coating without the staged curing process had a curing time extended to 72 hours and a salt spray resistance life reduced to 7500 hours. This indicates that due to the mismatch in reaction rates among the three types of reactions—epoxy-amine addition, mercapto-epoxy ring-opening, and siloxane hydrolysis-condensation—internal stress concentration occurred within the coating, leading to a decrease in the density of the crosslinked network. The results demonstrate that the staged curing process is a necessary condition to ensure the coating of this invention achieves its ultra-heavy-duty corrosion resistance.

[0056] Finally, it should be noted that the above embodiments are merely illustrative of several implementations of the present invention and are not intended to limit the scope of the invention. For those skilled in the art, any modifications, equivalent substitutions, or improvements made without departing from the concept of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A heavy-duty anti-corrosion coating that can be applied with oil, comprising a two-component system, characterized in that, include: Component A, by weight, comprises the following components: 8-12 parts of fluorosilicone modified polyacrylate-phosphate-catechol terpolymer, 20-25 parts of hydrogenated bisphenol A epoxy resin, 10-15 parts of polyaspartic acid ester resin, 0.5-1.0 parts of fluorinated graphene, 3-5 parts of aluminum tripolyphosphate, 4-6 parts of nano zinc oxide, 2-3 parts of fumed silica, and 35-55 parts of mixed solvent; Component B, by weight, comprises the following components: 40-50 parts of polyetheramine, 20-30 parts of alicyclic amine, 8-12 parts of hydroxyethyl methacrylate modified thioglycolate, 5-8 parts of melamine polyphosphate, 5-10 parts of aluminum hydroxide, 0.3-0.8 parts of dibutyltin dilaurate, and 2-10 parts of mixed solvent; The weight ratio of component A to component B is 100:25-35.

2. The heavy-duty anti-corrosion coating according to claim 1, characterized in that, The fluorosilicone-modified polyacrylate-phosphate-catechin terpolymer is prepared by the following steps: Step 1: Trimethylolpropane was reacted with 2-bromoisobutyryl bromide under pyridine catalysis to prepare the dibromo-ATRP initiator precursor TMP-Br2; Step 2: After reacting TMP-Br2 with trichlorophosphate, deionized water is added for hydrolysis to obtain the phosphate ester-functionalized dibromoATRP initiator TMP-PO(OH)2-Br2. Step 3: Using TMP-PO(OH)2-Br2 as an initiator and CuBr / PMDETA as a catalytic system, ATRP polymerization was carried out with trifluoroethyl methacrylate and methacryloxypropyltrimethoxysilane as mixed monomers to obtain polymer intermediates. Step 4: After azidation of the terminal bromine atoms of the polymer intermediate, it undergoes a CuAAC click chemical reaction with N-propynyl maleimide to obtain a polymer containing maleimide end groups. Step 5: The polymer containing maleimide end groups is reacted with dopamine hydrochloride in phosphate buffer, purified by dialysis, and then freeze-dried to obtain the fluorosilicone modified polyacrylate-phosphate-catechin terpolymer.

3. The heavy-duty anti-corrosion coating according to claim 2, characterized in that, In the first step, the molar ratio of trimethylolpropane to 2-bromoisobutyryl bromide is 1:2.0, the reaction temperature is 0-25℃, and the reaction time is 12h. In the second step, the molar ratio of trichlorophosphate to the hydroxyl group contained in TMP-Br2 is 1:1.05-1.15, the reaction temperature is 0-5℃, the molar ratio of deionized water to trichlorophosphate is 10-15:1, and the hydrolysis is carried out at room temperature for 4-6h.

4. The heavy-duty anti-corrosion coating according to claim 2, characterized in that, In the third step, the molar ratio of CuBr to initiator is 1:1, the molar ratio of PMDETA to CuBr is 1:1, the molar ratio of mixed monomers is 2:1, the molar ratio of mixed monomers to initiator is 15-20:1, the polymerization temperature is 60±2℃, and the polymerization time is 6-8h.

5. The heavy-duty anti-corrosion coating according to claim 2, characterized in that, In the fourth step, the molar ratio of sodium azide to terminal bromine atoms is 3:1, and the substitution reaction is carried out in DMF at 60℃ for 12 h; the molar ratio of CuSO4·5H2O to azide groups is 0.1:1, and the click chemistry reaction is carried out at room temperature for 6-8 h; in the fifth step, the pH of the phosphate buffer is 8.0-8.5, the reaction temperature is 30±2℃, the molar ratio of dopamine hydrochloride to maleimide groups is 1.2:1, the reaction time is 12-16 h, the dialysis molecular weight cutoff (MWCO) is 1000, and the dialysis time is 48 h.

6. The heavy-duty anti-corrosion coating according to claim 1, characterized in that, The mixed solvent is a mixture of xylene and n-butanol in a weight ratio of 7:3; the alicyclic amine is isophorone diamine; the polyether amine is polyether amine D-2000; the hydroxyethyl methacrylate modified mercaptoacetate is prepared by transesterification of mercaptoacetate and hydroxyethyl methacrylate, with a number average molecular weight of 300-500, and the molecular structure contains thiol, ester and acrylate double bonds simultaneously, with a thiol content of 8-10 wt%.

7. A method for preparing the ultra-heavyweight anti-corrosion coating according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: According to the weight parts of component A, add each component to the mixed solvent in sequence, and stir and disperse at 500-800 rpm for 1-2 hours to obtain component A; Step 2: According to the weight parts of component B, add each component to the mixed solvent in sequence, and stir and mix at 300-500 rpm for 0.5-1 h to obtain component B; Step 3: Before use, mix component A and component B at a weight ratio of 100:25-35, stir for 5-10 minutes, and let stand for 10-15 minutes to obtain the ultra-heavy anti-corrosion coating.

8. A method for applying the heavy-duty anti-corrosion coating according to any one of claims 1-6 to an oil-stained metal surface, characterized in that, Includes the following steps: Step 1: Provide oil content ≤500g / m 2 For metal substrates with rust content <100μm, there is no need to perform degreasing, rust removal, or drying treatment on the metal substrate; Step 2: Mix component A and component B at a weight ratio of 100:25-35 until homogeneous, and directly coat the mixture onto the surface of the metal substrate. The dry film thickness is 180-220 μm. Step 3: Curing the coating at 15-50℃ and relative humidity ≤85% according to a staged curing process to form a protective coating.

9. The coating method according to claim 8, characterized in that, The staged curing process is specifically as follows: First stage: Temperature 15-25℃, relative humidity 50-70%, curing time 6-12h; Second stage: Temperature 25-40℃, relative humidity 60-80%, curing time 12-24h; Third stage: ambient temperature and relative humidity <85%, curing time 24-48h.

10. The coating method according to claim 8, characterized in that, In step two, the coating method is one of brushing, rolling, or airless spraying; when using airless spraying, the spraying pressure is 15-20MPa, the nozzle diameter is 0.43-0.53mm, and the spraying distance is 30-40cm.

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