Water-based high-efficiency anticorrosive epoxy primer and preparation method thereof

Abstract

The present application belongs to the technical field of paint, and particularly relates to a water-based efficient anticorrosive epoxy primer and a preparation method thereof. The present application forms a dense crosslinking network through ring-opening addition of a secondary amine group of a water-based polyaspartic ester resin and an epoxy group of a water-based epoxy resin at normal temperature; microencapsulated 2-ethyl-4-methyl imidazole remains stable (half-life period > 30 days) during storage, and the shear stress causes the capsule to break and release the imidazole catalyst after construction or scratching, thereby accelerating curing and solving the contradiction between the “pot life and curing speed”. Secondly, the particle size grading of the ternary multi-scale filler (hollow microspheres, core-shell corrosion inhibitor and mica powder) enables the filler to be tightly packed, the void ratio is 10%-25%, a “labyrinth effect” is formed, the diffusion path of water vapor and chloride ions is prolonged, the high aspect ratio mica powder is arranged in parallel to enhance the barrier, and the hollow microspheres reduce the density and absorb impact energy.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a water-based high-efficiency anti-corrosion epoxy primer and its preparation method. This primer is particularly suitable for heavy-duty anti-corrosion applications requiring extremely high anti-corrosion performance, curing speed, and construction efficiency, such as protective coatings for large bridge steel structures, oil and gas pipelines, and international standard containers. Background Technology

[0002] In heavy-duty industrial sectors such as bridges, oil pipelines, and containers, traditional solvent-based epoxy primers, while offering excellent corrosion protection, contain large amounts of volatile organic compounds (VOCs), severely polluting the environment and endangering the health of construction workers. Their use has been gradually restricted by environmental regulations. While water-based epoxy primers offer a lower VOC emission as an alternative, they still have significant shortcomings in practical applications.

[0003] First, existing waterborne epoxy primers have a slow curing speed, especially in low-temperature or high-humidity environments, resulting in excessively long surface drying and hard-drying times, which severely impacts the production efficiency of assembly line operations such as bridge and container manufacturing. Second, for facilities like oil pipelines that require long-term underground burial or contact with corrosive media, existing waterborne primers often lack sufficient density and corrosion protection lifespan, making them unable to resist the penetration of chloride ions and moisture. Furthermore, existing waterborne primers often struggle to balance high hardness and toughness in terms of mechanical properties, making them prone to scratches during frequent container handling and transportation. Once the coating is damaged, corrosion can easily spread from the damaged area, leading to overall corrosion failure.

[0004] Therefore, developing a water-based epoxy primer that is both environmentally friendly and meets the stringent requirements of heavy-duty corrosion protection, possessing rapid curing, high hardness, excellent corrosion resistance, and self-healing properties after scratches, is a technical challenge that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based high-efficiency anti-corrosion epoxy primer and its preparation method, aiming to solve the problems of slow curing, insufficient anti-corrosion performance, poor mechanical properties and lack of self-healing ability after scratches in existing water-based primers, and to optimize it in particular for the application needs of bridges, oil pipelines and containers.

[0006] To achieve the above objectives, the first aspect of the present invention provides a water-based high-efficiency anti-corrosion epoxy primer, comprising the following raw materials in parts by weight: 60-80 parts of waterborne epoxy resin emulsion; 20-40 parts of waterborne polyaspartic acid ester resin; 15-30 parts of water-based phenolic amine curing agent; 5-15 parts of polymer hollow microspheres; Core-shell corrosion inhibitor, 8-20 parts; 10-30 parts of high aspect ratio mica powder; Microencapsulated 0.2-0.8 parts of 2-ethyl-4-methylimidazole; 1-3 parts of γ-glycidyl etheroxypropyltrimethoxysilane; 20-40 parts deionized water; 0.5-2 parts of wetting and dispersing agent; Defoamer 0.2-1 part; The ratio of the molar number of secondary amine groups in the waterborne polyaspartic acid ester resin to the molar number of epoxy groups in the waterborne epoxy resin is 1:0.8-1.2, and the half-life of the capsule wall of the microencapsulated 2-ethyl-4-methylimidazole at 25°C is greater than 30 days. The "half-life" refers to the time required for the content of microencapsulated 2-ethyl-4-methylimidazole to decay to 50% of its initial value. The test method is as follows: the microcapsule sample is sealed and stored in a constant temperature chamber at 25°C, and samples are taken every 5 days. The remaining imidazole content in the microcapsules is determined by high performance liquid chromatography, and the decay curve is calculated to obtain the half-life.

[0007] In some embodiments, the waterborne polyaspartic acid ester resin has a volume solids content ≥80%, a viscosity of 500-2000 mPa·s at 25°C, a molecular weight of 2000-5000 g / mol, and a secondary amine group content of 1.5-3.0 mmol / g in its molecular chain.

[0008] In some embodiments, the polymer hollow microspheres have a particle size distribution D50 of 1-10 μm, a bulk density of 0.1-0.5 g / cm³, and a compressive strength of 0.5-2.0 MPa; the high aspect ratio mica powder has an average particle size D50 of 5-15 μm, a thickness of 0.1-0.5 μm, an aspect ratio ≥20:1, and a specific surface area of ​​10-30 m² / g.

[0009] In some embodiments, the core-shell corrosion inhibitor has a shell-core bilayer structure. The shell is a thermosetting resin coating with a thickness of 50-200 nm and a glass transition temperature (Tg) > 120 °C. The core is a solid corrosion inhibitor particle with a D50 of 0.5-5 μm. The release rate of the core-shell corrosion inhibitor is 0.1-0.5 mg / h in a medium with pH=4 and less than 0.01 mg / h in a medium with pH=7. The release rate is tested by placing the core-shell corrosion inhibitor in a buffer solution of the corresponding pH value, stirring at 25 °C, taking samples every 24 hours, and determining the concentration of corrosion inhibitor ions in the supernatant using inductively coupled plasma atomic emission spectrometry (ICP-AES) to calculate the release amount per unit time.

[0010] In some embodiments, the particle size D50 of the microencapsulated 2-ethyl-4-methylimidazole is 2-8 μm, and the capsule wall thickness is 0.1-0.5 μm; under a shear rate greater than 1000 s⁻¹, the release rate of the microencapsulated 2-ethyl-4-methylimidazole is greater than 80%. The shear rate condition is simulated using a coaxial cylindrical rotational viscometer, with the rotor speed set at 500 rpm, corresponding to a shear rate of approximately 1200 s⁻¹. After shearing treatment at 25°C for 5 minutes, the imidazole content in the supernatant is measured, and the release rate is calculated.

[0011] In some embodiments, the polymer hollow microspheres, core-shell corrosion inhibitor, and high aspect ratio mica powder constitute a multi-scale filler system, with the particle size ratio of the three being (1-10):(0.5-5):(5-15). The porosity of the multi-scale filler system is 10%-25%, and the bulk density is 1.2-1.8 g / cm³. The porosity is tested by mixing the three fillers uniformly according to the specified ratio, placing them in a mold, and compacting them under a pressure of 10 MPa. The volume and true density of the compacted material are measured, and the porosity is calculated using the formula (1 - bulk density / true density) × 100%.

[0012] In some embodiments, the ratio of the amount of γ-glycidoxypropyltrimethoxysilane used to the total surface area of ​​the multi-scale filler system is 0.05-0.2 mg / m².

[0013] A second aspect of this invention provides a method for preparing a water-based, high-efficiency anti-corrosion epoxy primer, comprising the following steps: S1. Pre-dispersion: High aspect ratio mica powder, polymer hollow microspheres and core-shell structure corrosion inhibitor are added to deionized water and dispersed under high-speed shear for 20-30 minutes to form a dispersion. S2. Resin composite: Add waterborne epoxy resin emulsion and waterborne polyaspartic acid ester resin to the dispersion obtained in step S1, add γ-glycidyl etheroxypropyltrimethoxysilane, and stir and react at 40-50℃ to make the composite resin molecular chains interpenetrate and bond to the filler surface. S3. Mixing of curing components: Add water-based phenolic amine curing agent, microencapsulated 2-ethyl-4-methylimidazolium, wetting and dispersing agent and defoamer, stir evenly and filter to obtain the water-based high-efficiency anti-corrosion epoxy primer.

[0014] This invention achieves technical effects through the synergistic effect of multiple components, encompassing four dimensions: curing kinetics, physical barrier, chemical corrosion inhibition, and interfacial bonding. (1) In this invention, the secondary amine group of waterborne polyaspartic acid ester resin and the epoxy group of waterborne epoxy resin undergo ring-opening addition at room temperature to form a dense cross-linked network; the microencapsulated 2-ethyl-4-methylimidazolium remains stable during storage (half-life > 30 days), and the shear stress after construction or when scratched causes the capsule to rupture, releasing the imidazolium catalyst and accelerating curing, thus solving the contradiction of "the pot life and the curing speed cannot be obtained at the same time"; (2) The particle size distribution of the ternary multi-scale filler (hollow microspheres, core-shell corrosion inhibitors, mica powder) makes the filler tightly packed with a porosity of 10%-25%, forming a "maze effect" and extending the diffusion path of water vapor and chloride ions; the parallel arrangement of high aspect ratio mica powder enhances the barrier, and the hollow microspheres reduce the density and absorb impact energy. (3) The shell of the core-shell corrosion inhibitor is stable under normal pH conditions (release rate <0.01mg / h). When local corrosion causes the pH to drop, the shell degrades in response, and the corrosion inhibitor is released at 0.1-0.5mg / h, forming a precipitation film in the corrosion micro-area to achieve "release on demand". (4) The silanol groups of γ-glycidoxypropyltrimethoxysilane condense with the hydroxyl groups on the filler surface (condensation degree >90%), and the epoxy groups participate in the resin curing, forming chemical bonds between the filler and the resin, which significantly improves the adhesion and water resistance. At the same time, when the coating is scratched, the high shear stress (>1000s⁻¹) causes the microcapsules (wall thickness 0.1-0.5μm) to rupture, and the released 2-ethyl-4-methylimidazolium catalyzes the secondary cross-linking of the uncured resin, filling the microcracks and preventing the spread of corrosion.

[0015] Beneficial effects: (1) This invention has the characteristics of rapid curing and high hardness, surface drying time of less than 2 hours, actual drying time of less than 12 hours, pencil hardness of 2H-3H, which significantly improves construction efficiency. At the same time, it has excellent long-term corrosion resistance, resists salt spray for more than 1000 hours without rust, and effectively blocks water vapor and chloride ions. (2) The present invention has a certain self-repair function after scratching. Because the microcapsule rupture triggers in-situ polymerization of resin, repairs microcracks, prevents corrosion from spreading, and is environmentally friendly and safe with extremely low VOC content, meeting the strictest environmental protection standards. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0017] I. Raw material preparation: The preferred raw materials are as follows: Waterborne epoxy resin emulsion: Bisphenol A type epoxy emulsion, solid content 50-60%, epoxy equivalent 450-550g / eq, can be selected from Hansen Chemical's RSW 4680 or other commercially available products with equivalent performance.

[0018] Waterborne polyaspartic acid ester resin: solid content ≥80%, viscosity at 25℃ is 500-2000mPa·s. You can choose F520 from Feiyang Junyan or other commercially available products with equivalent performance.

[0019] Water-based phenolic amine curing agent: High activity and moisture resistance. You can choose Cardely's NX-8101 series or other commercially available products with equivalent performance.

[0020] Polymer hollow microspheres: Glass hollow microspheres with a particle size D50 of 1-10μm, such as 3M's iM30K or other commercially available products with equivalent performance.

[0021] Core-shell corrosion inhibitor: The core is strontium molybdate and the shell is modified acrylic resin. Actigard series from Hemings Corporation or other commercially available products with equivalent performance can be selected.

[0022] High aspect ratio mica powder: wet-processed sericite with an aspect ratio ≥ 20:1. 325 mesh wet-processed mica powder from Lingshou County Huajing Mica Co., Ltd. or other commercially available products with equivalent properties can be selected.

[0023] Microencapsulated 2-ethyl-4-methylimidazole: The capsule wall material is polyurea formaldehyde, and the core material is 2-ethyl-4-methylimidazole. Related products manufactured by Shikoku Chemical Research Institute or other commercially available products with equivalent properties can be selected.

[0024] γ-glycidoxypropyltrimethoxysilane: Momentive A-187 or other commercially available products with equivalent properties can be used.

[0025] Wetting and dispersing agents: Evonik Tego Dispers 750W or other commercially available products with equivalent performance can be used.

[0026] Defoamer: Evonik Tego Foamex 810 or other commercially available products with equivalent performance can be used.

[0027] Deionized water: conductivity <10μS / cm.

[0028] A method for preparing a water-based, high-efficiency anti-corrosion epoxy primer includes the following steps: S1. Pre-dispersion: Deionized water, high aspect ratio mica powder, polymer hollow microspheres and core-shell structure corrosion inhibitor are added to a dispersion vessel, a wetting and dispersing agent is added, and the mixture is dispersed for 20-30 minutes under high-speed shear at 1500-2000 r / min to form a dispersion. S2. Resin composite: Add waterborne epoxy resin emulsion and waterborne polyaspartic acid ester resin to the above dispersion, add γ-glycidyl etheroxypropyltrimethoxysilane, and stir and react at 40-50℃ for 0.5-1.5 hours to allow the composite resin molecular chains to interpenetrate and bond to the filler surface. S3. Mixing of curing components: Cool to room temperature, add water-based phenolic amine curing agent, microencapsulated 2-ethyl-4-methylimidazolium and defoamer, stir at low speed until uniform, 400-600 r / min, for 5-15 minutes, filter and discharge to obtain the water-based high-efficiency anti-corrosion epoxy primer.

[0029] Example 1 A water-based high-efficiency anti-corrosion epoxy primer: 70 parts of water-based epoxy resin emulsion, 30 parts of water-based polyaspartic acid ester resin, 22 parts of water-based phenolic amine curing agent, 10 parts of polymer hollow microspheres, 15 parts of core-shell structure corrosion inhibitor, 20 parts of high aspect ratio mica powder, 0.5 parts of microencapsulated 2-ethyl-4-methylimidazolium, 2 parts of γ-glycidyl etheroxypropyltrimethoxysilane, 30 parts of deionized water, 1 part of wetting and dispersing agent, and 0.5 parts of defoamer.

[0030] The coating was prepared according to steps S1-S3 described above. The resulting coating had a moderate solids content and good application viscosity. The porosity of the multi-scale filler system in this embodiment was determined to be 15%.

[0031] Example 2 A water-based high-efficiency anti-corrosion epoxy primer: 60 parts of water-based epoxy resin emulsion, 40 parts of water-based polyaspartic acid ester resin, 30 parts of water-based phenolic amine curing agent, 15 parts of polymer hollow microspheres, 20 parts of core-shell structure corrosion inhibitor, 30 parts of high aspect ratio mica powder, 0.8 parts of microencapsulated 2-ethyl-4-methylimidazolium, 3 parts of γ-glycidyl etheroxypropyltrimethoxysilane, 35 parts of deionized water, 1.5 parts of wetting and dispersing agent, and 0.8 parts of defoamer.

[0032] The preparation was carried out according to steps S1-S3 described above. This formulation focuses on the improved corrosion resistance resulting from a high filler content. The porosity of the multi-scale filler system in this embodiment was determined to be 12%.

[0033] Example 3 A water-based high-efficiency anti-corrosion epoxy primer: 80 parts of water-based epoxy resin emulsion, 20 parts of water-based polyaspartic acid ester resin, 15 parts of water-based phenolic amine curing agent, 5 parts of polymer hollow microspheres, 8 parts of core-shell structure corrosion inhibitor, 10 parts of high aspect ratio mica powder, 0.2 parts of microencapsulated 2-ethyl-4-methylimidazolium, 1 part of γ-glycidyl etheroxypropyltrimethoxysilane, 25 parts of deionized water, 0.5 parts of wetting and dispersing agent, and 0.2 parts of defoamer.

[0034] The preparation was carried out according to steps S1-S3 described above. This formulation focuses on the leveling and adhesion benefits resulting from the high resin content. The porosity of the multi-scale filler system in this embodiment was determined to be 21%.

[0035] Comparative Example 1 A water-based high-efficiency anti-corrosion epoxy primer: Weigh 100 parts of water-based epoxy resin emulsion, 25 parts of water-based polyamide curing agent, 10 parts of polymer hollow microspheres, 15 parts of core-shell structure corrosion inhibitor, 20 parts of high aspect ratio mica powder, 35 parts of deionized water, 1 part of wetting and dispersing agent, and 0.5 parts of defoamer.

[0036] The preparation method is the same as in Example 1, but without the addition of waterborne polyaspartic acid ester resin, waterborne phenolic amine curing agent and microencapsulation accelerator.

[0037] Comparative Example 2 A water-based high-efficiency anti-corrosion epoxy primer: 70 parts of water-based epoxy resin emulsion, 30 parts of water-based polyaspartic acid ester resin, 22 parts of water-based phenolic amine curing agent, 45 parts of ordinary talc powder (D50 is 10μm), 0.5 parts of microencapsulated 2-ethyl-4-methylimidazolium, 2 parts of γ-glycidyl etheroxypropyltrimethoxysilane, 30 parts of deionized water, 1 part of wetting and dispersing agent, and 0.5 parts of defoamer.

[0038] The preparation method is the same as in Example 1, but without the addition of polymer hollow microspheres, core-shell corrosion inhibitors and high aspect ratio mica powder.

[0039] Comparative Example 3 A water-based high-efficiency anti-corrosion epoxy primer: 70 parts of water-based epoxy resin emulsion, 30 parts of water-based polyaspartic acid ester resin, 22 parts of water-based phenolic amine curing agent, 10 parts of polymer hollow microspheres, 15 parts of core-shell structure corrosion inhibitor, 20 parts of high aspect ratio mica powder, 0.5 parts of unmicroencapsulated ordinary 2-ethyl-4-methylimidazole, 2 parts of γ-glycidyl etheroxypropyltrimethoxysilane, 30 parts of deionized water, 1 part of wetting and dispersing agent, and 0.5 parts of defoamer.

[0040] The preparation method is the same as in Example 1.

[0041] Comparative Example 4 A water-based high-efficiency anti-corrosion epoxy primer: 70 parts of water-based epoxy resin emulsion, 30 parts of water-based polyaspartic acid ester resin, 22 parts of water-based phenolic amine curing agent, 10 parts of polymer hollow microspheres, 15 parts of core-shell structure corrosion inhibitor, 20 parts of high aspect ratio mica powder, 0.5 parts of microencapsulated 2-ethyl-4-methylimidazole, 30 parts of deionized water, 1 part of wetting and dispersing agent, and 0.5 parts of defoamer.

[0042] The preparation method is the same as in Example 1, but without the addition of γ-glycidoxypropyltrimethoxysilane.

[0043] Comparative Example 5 A water-based high-efficiency anti-corrosion epoxy primer: Weigh 50 parts of water-based epoxy resin emulsion and 50 parts of water-based polyaspartic acid ester resin, and the rest are the same as in Example 1.

[0044] The preparation method is the same as in Example 1.

[0045] Comparative Example 6 A water-based high-efficiency anti-corrosion epoxy primer: Weigh 25 parts of polymer hollow microspheres (3M iM30K), and the rest is the same as in Example 1.

[0046] The preparation method is the same as in Example 1.

[0047] Comparative Example 7 A water-based high-efficiency anti-corrosion epoxy primer: Weigh 15 parts of ordinary strontium molybdate (uncoated, D50 is 2μm) to replace the core-shell structure corrosion inhibitor, and the rest is the same as in Example 1.

[0048] The preparation method is the same as in Example 1.

[0049] Comparative Example 8 Microcapsules were prepared with a wall thickness of 0.05 μm, and other procedures were the same as in Example 1.

[0050] The preparation method is the same as in Example 1.

[0051] Comparative Example 9 Microcapsules were prepared with a wall thickness of 0.8 μm, and other procedures were the same as in Example 1.

[0052] The preparation method is the same as in Example 1.

[0053] II. Performance Testing and Result Analysis: 2.1 The coatings from the above examples and comparative examples were sprayed onto sandblasted Q235 steel plates (Sa2.5 grade), with the film thickness controlled at (60±5) μm. Curing conditions: 25℃±2℃, relative humidity 50%±5%.

[0054] 2.2 Test Methods 2.3 Test Results Table 1 shows the detection results of the example: Table 1 Table 2 shows the test results for the comparative examples: Table 2 III. Results Analysis (1) The surface drying time of Examples 1-3 was <2h, the actual drying time was <10h, and the pot life was >3h; the actual drying time of Comparative Example 1 (without aspartic resin) was up to 18h; the pot life of Comparative Example 3 (free imidazole) was <0.5h; the storage stability of Comparative Example 8-1 (too thin wall thickness) was poor (viscosity change rate >50%); the release rate after scratching of Comparative Example 8-2 (too thick wall thickness) was <30%. It can be concluded that the present invention achieves the unity of storage stability, rapid construction and scratch repair through the synergy of aspartic resin and microcapsules; (2) Example 1 showed no rust after 1000h of salt spray resistance; Comparative Example 2 (traditional talc powder) showed edge rust after only 600h of salt spray resistance; Comparative Example 6 (excessive hollow microspheres) had excessively high porosity and blistering during salt spray resistance. It can be concluded that the "maze effect" formed by the multi-scale filler gradation significantly prolongs the diffusion path of the corrosive medium; (3) No corrosion spread at the scratch in Example 1; severe corrosion spread at the scratch in Comparative Example 7 (ordinary corrosion inhibitor); the release rate of the core-shell corrosion inhibitor was 0.1-0.5 mg / h at pH=4 and <0.01 mg / h at pH=7, which shows that the pH-responsive on-demand release mechanism is effective. (4) Example 1 showed an adhesion of 12.5 MPa and no abnormalities in water resistance for 240 h; Comparative Example 4 (without silane) showed an adhesion of 9.0 MPa and foaming in water resistance. It can be concluded that silanol and filler hydroxyl groups undergo a condensation reaction to form chemical bonds. (5) In Example 1, no corrosion spread was observed after 500 hours of salt spray testing on the scratches, and scanning electron microscopy showed that the scratches were filled with resin polymers; in Comparative Example 3 (free imidazole) and Comparative Example 9 (excessive wall thickness), corrosion spread was obvious at the scratches. It can be concluded that the microcapsules rupture and release the catalyst when scratched, initiating in-situ polymerization to repair the microcracks; (6) When the porosity is less than 10%, the filler is too dense, which increases the brittleness of the coating and reduces the impact strength to below 35cm. When the porosity is greater than 25%, the water vapor permeation path increases and the salt spray resistance time drops to below 600h. When the porosity is 12%-22%, the salt spray resistance time exceeds 900h and the impact strength is ≥45cm.

[0055] In summary, the waterborne high-efficiency anti-corrosion epoxy primer provided by this invention, through waterborne epoxy / polyaspartic acid ester resin compounding technology and multi-scale filler / microcapsule functional design, and through precise control of the dosage range of key components and microcapsule structural parameters, successfully solves the pain points of waterborne coatings in the field of heavy-duty anti-corrosion, and achieves a perfect unity of environmental protection, workability and protection.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-based, high-efficiency anti-corrosion epoxy primer, characterized in that, Including the following parts by weight of raw materials: 60-80 parts of waterborne epoxy resin emulsion; 20-40 parts of waterborne polyaspartic acid ester resin; 15-30 parts of water-based phenolic amine curing agent; 5-15 parts of polymer hollow microspheres; Core-shell corrosion inhibitor, 8-20 parts; 10-30 parts of high aspect ratio mica powder; Microencapsulated 0.2-0.8 parts of 2-ethyl-4-methylimidazole; 1-3 parts of γ-glycidyl etheroxypropyltrimethoxysilane; 20-40 parts deionized water; 0.5-2 parts of wetting and dispersing agent; Defoamer 0.2-1 part; The ratio of the molar number of secondary amine groups in the waterborne polyaspartic acid ester resin to the molar number of epoxy groups in the waterborne epoxy resin is 1:0.8-1.2, and the capsule wall of the microencapsulated 2-ethyl-4-methylimidazole has a half-life of more than 30 days at 25°C.

2. The water-based high-efficiency anti-corrosion epoxy primer according to claim 1, characterized in that, The waterborne polyaspartic acid ester resin has a volume solids content ≥80%, a viscosity of 500-2000 mPa·s at 25°C, a molecular weight of 2000-5000 g / mol, and a secondary amine group content of 1.5-3.0 mmol / g in its molecular chain.

3. The water-based high-efficiency anti-corrosion epoxy primer according to claim 1, characterized in that, The hollow polymer microspheres have a particle size distribution D50 of 1-10 μm, a bulk density of 0.1-0.5 g / cm³, and a compressive strength of 0.5-2.0 MPa; the high aspect ratio mica powder has an average particle size D50 of 5-15 μm, a thickness of 0.1-0.5 μm, an aspect ratio ≥20:1, and a specific surface area of ​​10-30 m² / g.

4. The water-based high-efficiency anti-corrosion epoxy primer according to claim 1, characterized in that, The core-shell structured corrosion inhibitor has a shell-core double-layer structure. The shell is a thermosetting resin coating with a thickness of 50-200 nm and a glass transition temperature (Tg) > 120 °C. The core is a solid corrosion inhibitor particle with a D50 of 0.5-5 μm. The release rate of the core-shell structured corrosion inhibitor is 0.1-0.5 mg / h in a medium with pH=4 and less than 0.01 mg / h in a medium with pH=7.

5. The water-based high-efficiency anti-corrosion epoxy primer according to claim 1, characterized in that, The microencapsulated 2-ethyl-4-methylimidazole has a particle size D50 of 2-8 μm and a capsule wall thickness of 0.1-0.5 μm; under a shear rate greater than 1000 s⁻¹, the release rate of the microencapsulated 2-ethyl-4-methylimidazole is greater than 80%.

6. The water-based high-efficiency anti-corrosion epoxy primer according to claim 1, characterized in that, The polymer hollow microspheres, core-shell corrosion inhibitor, and high aspect ratio mica powder constitute a multi-scale filler system. The particle size ratio of the polymer hollow microspheres, core-shell corrosion inhibitor, and high aspect ratio mica powder is (1-10):(0.5-5):(5-15). The porosity of the multi-scale filler system is 10%-25%, and the bulk density is 1.2-1.8 g / cm³.

7. The water-based high-efficiency anti-corrosion epoxy primer according to claim 6, characterized in that, The ratio of the amount of γ-glycidyl etheroxypropyltrimethoxysilane used to the total surface area of ​​the multi-scale packing system is 0.05-0.2 mg / m², and the degree of condensation between the silanol groups and the hydroxyl groups on the packing surface after hydrolysis is greater than 90%.

8. A method for preparing a water-based high-efficiency anti-corrosion epoxy primer as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Pre-dispersion: High aspect ratio mica powder, polymer hollow microspheres and core-shell structure corrosion inhibitor are added to deionized water and dispersed under high-speed shear for 20-30 minutes to form a dispersion. S2. Resin composite: Add waterborne epoxy resin emulsion and waterborne polyaspartic acid ester resin to the dispersion obtained in step S1, add γ-glycidyl etheroxypropyltrimethoxysilane, and stir and react at 40-50℃ to make the composite resin molecular chains interpenetrate and bond to the filler surface. S3. Mixing of curing components: Add water-based phenolic amine curing agent, microencapsulated 2-ethyl-4-methylimidazolium, wetting and dispersing agent and defoamer, stir evenly and filter to obtain the water-based high-efficiency anti-corrosion epoxy primer.

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