Water-based epoxy anticorrosive paint and preparation method thereof

Abstract

This invention discloses a waterborne epoxy anticorrosive paint and its preparation method. The anticorrosive paint is a two-component system, including component A and component B. Component A includes a self-emulsifying epoxy resin emulsion, a supported nano-anticorrosive microcapsules, and a functional filler compound system. Component B includes a waterborne epoxy curing agent. The self-emulsifying epoxy resin emulsion is formed by reacting bisphenol A type epoxy resin with polyetheramine to obtain a polymer with an amphiphilic block structure, and then dispersing it in water via phase inversion. The supported nano-anticorrosive microcapsules are hollow cerium dioxide microspheres loaded with corrosion inhibitors. By chemically modifying the epoxy resin with polyetheramine through chain extension, surface-active polyether segments are covalently bonded to the resin backbone, significantly improving the intrinsic water resistance and wet adhesion of the coating.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically referring to a water-based epoxy anti-corrosion paint and its preparation method. Background Technology

[0002] Metal corrosion and its protection have long been major challenges in the industrial sector. Epoxy resin coatings are widely used in metal corrosion protection due to their excellent adhesion, chemical resistance, and mechanical strength. However, traditional solvent-based epoxy coatings contain large amounts of volatile organic compounds (VOCs), posing hazards to the environment and the health of construction workers. With increasingly stringent environmental regulations, the development of low-VOC or even zero-VOC waterborne epoxy anti-corrosion paints has become an inevitable trend in the industry.

[0003] Currently, existing waterborne epoxy anticorrosive paints typically employ external emulsifiers to prepare emulsions, or introduce hydrophilic groups (such as carboxyl groups) into the epoxy resin backbone to achieve self-emulsification. However, these technical solutions still suffer from the following technical drawbacks in practical applications: Insufficient water resistance and density of the coating: Added small-molecule emulsifiers or excessive hydrophilic groups introduced will remain in the system after the coating has cured, forming hydrophilic micro-regions. These micro-regions can easily become channels for water molecules, oxygen and corrosive ions (such as chloride ions) to penetrate, leading to early blistering of the coating, decreased adhesion, and a significant reduction in long-term corrosion resistance.

[0004] The corrosion protection mechanism is simplistic and lacks active protection capabilities: Most existing water-based epoxy coatings rely on the physical barrier effect of the coating itself, which is a passive protection method. Once the coating develops microcracks or damages during construction or service, corrosive media will quickly reach the surface of the metal substrate, triggering electrochemical corrosion. The corrosion will then spread rapidly along the interface, leading to large-area failure of the coating.

[0005] Poor compatibility and synergistic effect of functional fillers: To improve corrosion resistance, existing technologies attempt to add a single type of anti-corrosion filler, such as adding only glass flakes for physical shielding, only zinc powder for cathodic protection, or only phosphate for passivation. Single filler systems often fail to address all aspects simultaneously, making it difficult to construct an efficient physical shielding layer, a stable passivation film, and an effective corrosion current dissipation network in the coating. This results in a significant bottleneck effect, failing to achieve multi-dimensional and all-round protection for the metal substrate.

[0006] Therefore, how to fundamentally solve the bottleneck of poor water resistance of waterborne epoxy resin itself, and endow the coating with intelligent and active anti-corrosion function, and build an efficient multi-level synergistic protection system, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the needs and problems mentioned in the background above, the present invention provides a water-based epoxy anti-corrosion paint and its preparation method, thereby at least partially solving the above problems.

[0008] According to the technical solution of the present invention, a water-based epoxy anticorrosion paint is provided, wherein the anticorrosion paint is a two-component system, including component A and component B; Component A includes a self-emulsifying epoxy resin emulsion, a supported nano-corrosion-resistant microcontainer, and a functional filler compound system. Component B includes a water-based epoxy curing agent; The self-emulsifying epoxy resin emulsion is formed by reacting bisphenol A type epoxy resin with polyetheramine to obtain a polymer with an amphiphilic block structure, and then dispersing it in water by a phase inversion method. The loaded nano-corrosion-resistant microcontainer is a hollow cerium dioxide microsphere loaded with a corrosion inhibitor, and the surface of the hollow cerium dioxide microsphere is coated with a polymer encapsulation layer. The functional filler compound system includes at least a mixture of sheet-like physical shielding fillers, conductive nanofillers, and chemically passivated fillers.

[0009] Preferably, the polyetheramine is a polyether diamine with a number-average molecular weight of 400-4000; The molar ratio of the bisphenol A type epoxy resin to the polyetheramine in the chain extension reaction is (1.5-3):1.

[0010] Preferably, the corrosion inhibitor includes organic corrosion inhibitors and / or inorganic corrosion inhibitors; The organic corrosion inhibitor is benzotriazole; The inorganic corrosion inhibitor is at least one of molybdate or cerium salt; The polymer encapsulation layer is a polydopamine layer.

[0011] Preferably, the sheet-like physical shielding filler includes at least one of sericite, talc, and glass flakes; The conductive nanofiller includes at least one of fluorinated graphene, conductive carbon black, and modified carbon nanotubes. The chemically passivated filler includes at least one of aluminum tripolyphosphate, zinc phosphate, and zinc molybdate.

[0012] Preferably, component A comprises, by weight parts: 30-60 parts of self-emulsifying epoxy resin emulsion (in solids), 1-10 parts of load-bearing nano-corrosion-resistant micro-containers, 5-20 parts of sheet-like physical shielding filler, 0.5-5 parts of conductive nano-filler, 5-15 parts of chemically passivated filler, 0-5 parts of additives, and 10-30 parts of deionized water. Component B comprises: 40-70 parts of water-based epoxy curing agent, 0-15 parts of co-solvent and 10-30 parts of deionized water; The mass mixing ratio of component A to component B is 100:(15-40).

[0013] In a second aspect, the present invention provides a method for preparing a water-based epoxy anti-corrosion paint, comprising the following steps: S1. Under inert gas protection, bisphenol A type epoxy resin and polyetheramine are mixed and reacted at 70-120℃ for 1-4 hours to obtain polyetheramine modified epoxy resin intermediate; after cooling, deionized water containing organic acid is slowly added under stirring, and self-emulsifying epoxy resin emulsion is obtained by phase inversion method. S2. Provide hollow cerium dioxide microspheres, load a corrosion inhibitor into the hollow cavity of the hollow cerium dioxide microspheres, and then coat the surface of the microspheres with a polymer encapsulation layer to obtain a loaded nano-corrosion-resistant microcontainer; S3. Mix deionized water, additives, chemical passivation fillers and sheet-like physical shielding fillers according to the formula, and disperse and grind them until the fineness is ≤50 micrometers; then add the self-emulsifying epoxy resin emulsion prepared in S1, the supported nano-corrosion-resistant micro-container prepared in S2 and the conductive nano-filler in sequence, stir evenly, filter, and obtain component A. S4. Mix the water-based epoxy curing agent, co-solvent, and deionized water according to the specified ratio, stir evenly, and filter to obtain component B.

[0014] Preferably, the molar ratio of bisphenol A epoxy resin to polyetheramine in S1 is (1.5-3):1; The polyetheramine is a polyether diamine with a number average molecular weight of 400-4000; the solid content of the self-emulsifying epoxy resin emulsion is 40-60%.

[0015] Preferably, in step S2, loading the corrosion inhibitor into the hollow cavity of the hollow cerium dioxide microspheres includes the following steps: Hollow cerium dioxide microspheres are dispersed in a solution containing a corrosion inhibitor and loaded by vacuum impregnation or high-pressure adsorption. The process of coating the microspheres with a polymer encapsulation layer includes the following steps: The microspheres loaded with corrosion inhibitor were dispersed in a weakly alkaline buffer solution of dopamine and stirred for 6-24 hours to allow dopamine to oxidize and self-polymerize on the surface of the microspheres to form a polydopamine layer. Then, the microspheres were separated, washed, and dried.

[0016] Preferably, the dispersion and grinding to a fineness of ≤50 micrometers in step S3 is carried out using a high-speed disperser and grinding equipment; The mixing process is carried out at a low speed of 20-80 rpm to avoid damaging the structure of the nanofiller.

[0017] Thirdly, the present invention also provides an application of a waterborne epoxy anticorrosive paint, wherein the waterborne epoxy anticorrosive paint prepared according to the method of preparation of the waterborne epoxy anticorrosive paint is used in the field of metal substrate corrosion protection. The application involves mixing component A and component B, applying the mixture to the surface of a metal substrate, and curing it to form an anti-corrosion coating; the metal substrate includes at least one of carbon steel, cast iron, and aluminum alloy; the application areas include anti-corrosion protection for bridges, ships, pipelines, containers, and marine engineering equipment.

[0018] Beneficial effects: 1. This invention utilizes polyetheramine to chemically extend the chain of epoxy resin, covalently integrating surface-active polyether segments into the resin backbone. This self-emulsifying method completely avoids the physical residue of small-molecule emulsifiers. The resulting nonionic hydrophilic segments maintain good stability after coating curing, preventing migration and the formation of hydrophilic channels, thus significantly improving the coating's intrinsic water resistance and wet adhesion. Simultaneously, the introduced flexible polyether segments effectively increase the flexibility of the cured crosslinking network, overcoming the brittleness caused by the high crosslinking density of epoxy resin, achieving a balanced performance of both rigidity and flexibility in the coating.

[0019] 2. This invention, through systematic innovation in resin molecular structure design, functionalization of nano-containers, and synergistic compounding of functional fillers, enables the prepared waterborne epoxy anticorrosive paint to achieve a leapfrog improvement in key indicators such as salt spray resistance, water resistance, adhesion, and impact resistance. It can meet the long-term protection requirements of C5 or even higher corrosion levels and can be widely used in bridges, ships, pipelines, containers, marine engineering equipment, and other fields, with extremely high industrial application value and market prospects. Detailed Implementation

[0020] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0021] This invention first provides a water-based epoxy anti-corrosion paint, which is a two-component system comprising component A and component B; Component A comprises: a self-emulsifying epoxy resin emulsion, a supported nano-corrosion-resistant microcontainer, and a functional filler compound system. Component B comprises: an aqueous epoxy curing agent; The self-emulsifying epoxy resin emulsion is a stable emulsion formed by chain extension reaction of bisphenol A epoxy resin and polyetheramine to obtain a polymer with an amphiphilic block structure, and then dispersing it in water by phase inversion. The loaded nano-corrosion-resistant microcontainer is a hollow cerium dioxide microsphere loaded with corrosion inhibitor, and its surface is coated with a pH-responsive polymer encapsulation layer. The functional filler compound system comprises at least a mixture of sheet-like physical shielding fillers, conductive nanofillers, and chemically passivated fillers.

[0022] Preferably, the polyetheramine is a polyether diamine with a number-average molecular weight of 400-4000. By controlling the molecular weight of the polyetheramine and its feeding ratio with epoxy resin, the particle size, stability, and final coating flexibility of the emulsion can be controlled.

[0023] Preferably, the corrosion inhibitor is an organic corrosion inhibitor and / or an inorganic corrosion inhibitor, such as one or more of benzotriazole, molybdate, and cerium salt. The encapsulation layer is preferably a polydopamine layer.

[0024] Preferably, in the functional filler compound system, the sheet-like physical shielding filler is selected from one or more of sericite, talc, and glass flakes; the conductive nanofiller is selected from one or more of fluorinated graphene, conductive carbon black, and modified carbon nanotubes; and the chemical passivation filler is selected from one or more of aluminum tripolyphosphate, zinc phosphate, and zinc molybdate.

[0025] More specifically, component A comprises the following components by weight: 30-60 parts of self-emulsifying epoxy resin emulsion (by solids), 1-10 parts of load-bearing nano-corrosion-resistant micro-containers, 5-20 parts of sheet-like physical shielding filler, 0.5-5 parts of conductive nano-filler, 5-15 parts of chemically passivated filler, 0-5 parts of additives, and 10-30 parts of deionized water.

[0026] Component B comprises the following components by weight: 40-70 parts of water-based epoxy curing agent, 0-15 parts of co-solvent and 10-30 parts of deionized water.

[0027] The mass mixing ratio of component A to component B is 100:15-40.

[0028] The present invention further provides a method for preparing the above-mentioned waterborne epoxy anticorrosive paint, comprising the following steps: S1. Preparation of self-emulsifying epoxy resin: Under inert gas protection, bisphenol A type epoxy resin and polyetheramine are mixed at a molar ratio of 1.5-3:1 and reacted at 70-120℃ for 1-4 hours to obtain a polyetheramine-modified epoxy resin intermediate. After cooling, deionized water containing organic acid is slowly added under stirring, and a self-emulsifying epoxy resin emulsion with a solid content of 40-60% is obtained by phase inversion.

[0029] S2. Preparation of supported nano-corrosion-resistant microcapsules: (1) Provide hollow cerium dioxide microsphere templates; (2) Disperse hollow cerium dioxide microspheres in a solution containing corrosion inhibitor, and load the corrosion inhibitor into the hollow cavity of the microspheres by vacuum impregnation or high pressure adsorption to obtain hollow cerium dioxide microspheres loaded with corrosion inhibitor. (3) Disperse the hollow cerium dioxide microspheres loaded with corrosion inhibitor in a weakly alkaline buffer solution of dopamine and stir for 6-24 hours to allow dopamine to oxidize and self-polymerize on the surface of the microspheres to form a polydopamine encapsulation layer; separate, wash and dry to obtain the loaded nano-corrosion-resistant microcontainer.

[0030] S3. Prepare component A: According to the formula, deionized water, additives, chemical passivation filler and sheet-like physical shielding filler are mixed and dispersed and ground at high speed until the fineness is ≤50 micrometers; then, under stirring conditions, the self-emulsifying epoxy resin emulsion prepared by S1, the supported nano-corrosion-resistant micro-container prepared by S2 and the conductive nano-filler are added in sequence, and the mixture is stirred evenly and filtered to obtain component A.

[0031] S4. Preparation of component B: Mix the water-based epoxy curing agent, co-solvent, and deionized water according to the specified ratio, stir at low speed until homogeneous, and filter to obtain component B.

[0032] Application and Construction of Waterborne Epoxy Anticorrosive Coatings: During construction, mix component A and component B evenly according to the stated mass mixing ratio, adjust the construction viscosity, and apply it to the pretreated metal substrate surface by spraying, brushing or rolling. The coating is then cured at room temperature or low temperature to form an anti-corrosion coating.

[0033] It should be noted that this invention uses polyetheramine to chemically extend the chain of epoxy resin, covalently incorporating surface-active polyether segments into the resin backbone. This self-emulsifying method completely avoids the physical residue of small-molecule emulsifiers. The resulting nonionic hydrophilic segments maintain good stability after coating curing and do not migrate to form hydrophilic channels, significantly improving the intrinsic water resistance and wet adhesion of the coating. Simultaneously, the introduced flexible polyether segments effectively increase the flexibility of the crosslinking network of the cured material, overcoming the brittleness caused by the high crosslinking density of epoxy resin, and achieving a balance between rigidity and flexibility in the coating performance.

[0034] A nanocontainer system was constructed, using hollow cerium dioxide as the container, polydopamine as the valve, and a corrosion inhibitor as the contents. The technical principle is as follows: Intelligent release: When the coating is partially damaged and the metal corrodes, the pH value of the corroded micro-region changes significantly (alkaline in the cathode area, acidic in the anodic area). The polydopamine encapsulation layer is pH responsive; under this microenvironmental change, its structure expands or disintegrates, thereby opening the valve.

[0035] Dual repair: On the one hand, the released organic / inorganic corrosion inhibitors rapidly migrate to the exposed metal surface, forming an adsorption film or passivation film to inhibit the corrosion reaction; on the other hand, the cerium dioxide shell itself has excellent activity and can combine with corrosion products to further enhance the passivation effect. This corrosion-triggered-on-demand-dual-repair mechanism achieves a leap from passive barrier to active repair, greatly extending the service life of the coating.

[0036] The synergistic effect of the ternary composite system consisting of sheet-like physical shielding filler, conductive nanofiller, and chemically passivated filler is manifested in: Physical shielding (maze effect): Micron-sized sheet-like fillers (such as sericite) are stacked layer by layer in the coating, which greatly extends the penetration path of water, oxygen and corrosive media.

[0037] Conductive Dissipation (Cathode Protection / Dispersion Current): Nanoscale conductive fillers (such as fluorinated graphene) form a micro-conductive network in the coating. On the one hand, they can disperse and dissipate the corrosion current reaching the substrate; on the other hand, their excellent hydrophobicity and layered structure can form multi-level barriers with the sheet-like fillers, filling the gaps between the micron-sized fillers and making the coating more compact.

[0038] Chemical passivation (anodic suppression): Chemical passivation fillers (such as aluminum tripolyphosphate) are slightly soluble in water and can react with iron ions dissolved from the anode to form a dense passivation film that covers the metal surface or coating micropores, further suppressing the anodic reaction.

[0039] The three elements work together to create a three-dimensional protective system within the coating, integrating physical barrier, electron dissipation, and chemical passivation.

[0040] Example 1 S1. Preparation of self-emulsifying epoxy resin: Under nitrogen protection, bisphenol A type epoxy resin (E-51) and polyetheramine (D2000, number average molecular weight 2000) were mixed at a molar ratio of 2:1 and reacted at 85°C for 2.5 hours to obtain a polyetheramine-modified epoxy resin intermediate. The mixture was then cooled to 60°C, and deionized water containing glacial acetic acid was slowly added while stirring. A self-emulsifying epoxy resin emulsion with a solid content of 50% was obtained via a phase inversion method.

[0041] S2. Preparation of supported nano-corrosion-resistant microcapsules (1) Hollow cerium dioxide microspheres were prepared by template method; (2) Hollow cerium dioxide microspheres were dispersed in an ethanol solution containing benzotriazole (BTA), vacuum impregnated for 12 hours, and centrifuged and dried to obtain hollow cerium dioxide microspheres loaded with corrosion inhibitor. (3) Disperse the hollow cerium dioxide microspheres loaded with corrosion inhibitor in Tris-HCl buffer solution of dopamine (pH=8.5), stir for 12 hours to allow dopamine to oxidize and self-polymerize on the surface of the microspheres to form a polydopamine encapsulation layer; centrifuge, wash and dry to obtain the loaded nano-corrosion-resistant microcontainer.

[0042] S3. Preparation of component A Mix 20 parts of deionized water, 1 part of BYK-190 dispersant, 10 parts of chemically passivated aluminum tripolyphosphate filler, and 10 parts of sheet-like physical shielding filler sericite, and disperse and grind at high speed until the fineness is ≤50μm; then, under stirring conditions, add in sequence the self-emulsifying epoxy resin emulsion prepared in S1, the supported nano-corrosion-resistant microcontainer prepared in S2, and 1 part of conductive nano-filler fluorinated graphene, continue stirring until uniform, filter, and obtain component A.

[0043] S4. Preparation of Component B Mix 50 parts of phenolic amine modified waterborne curing agent, 8 parts of propylene glycol methyl ether and 15 parts of deionized water, stir at low speed until uniform, filter, and obtain component B.

[0044] Example 2 The difference from Example 1 is as follows: Group A mix: 18 parts deionized water, 0.5 parts BYK-190 dispersant, 12 parts chemically passivated filler zinc phosphate, and 15 parts flaky physical shielding filler talc; 3 parts conductive nanofiller conductive carbon black.

[0045] Group B proportion: Mix 60 parts of phenolic amine modified waterborne curing agent, 10 parts of propylene glycol methyl ether and 18 parts of deionized water.

[0046] Example 3 The difference from Example 1 is as follows: Group A mix: 15 parts deionized water, 1.5 parts BYK-190 dispersant, 15 parts chemically passivated filler zinc molybdate, and 20 parts sheet-like physical shielding filler glass flakes; 5 parts conductive nanofiller fluorinated graphene.

[0047] Group B proportion: Mix 70 parts of phenolic amine modified waterborne curing agent, 12 parts of propylene glycol methyl ether and 20 parts of deionized water.

[0048] Example 4 The difference from Example 1 is as follows: Group A mix: 25 parts deionized water, 1 part BYK-190 dispersant, 5 parts chemically passivated filler aluminum tripolyphosphate, and 5 parts sheet-like physical shielding filler sericite; 0.5 parts conductive nanofiller conductive carbon black.

[0049] Group B proportion: Mix 40 parts of phenolic amine modified waterborne curing agent, 5 parts of propylene glycol methyl ether and 10 parts of deionized water.

[0050] Example 5 The difference from Example 1 is as follows: Group A mix: 22 parts deionized water, 1 part BYK-190 dispersant, 10 parts chemically passivated zinc phosphate filler, and 12 parts sericite sheet-like physical shielding filler; 2 parts conductive nanofiller modified carbon nanotubes.

[0051] Group B proportion: Mix 55 parts of phenolic amine modified waterborne curing agent, 15 parts of propylene glycol methyl ether and 25 parts of deionized water.

[0052] Example 6 The difference from Example 1 is as follows: Group A mix: 20 parts deionized water, 1 part BYK-190 dispersant, 8 parts chemically passivated filler aluminum tripolyphosphate, and 8 parts sheet-like physical shielding filler talc; 2 parts conductive nanofiller fluorinated graphene.

[0053] Group B proportion: Mix 65 parts of phenolic amine modified waterborne curing agent, 8 parts of propylene glycol methyl ether and 15 parts of deionized water.

[0054] Example 7 The difference from Example 1 is as follows: Group A mix: 25 parts deionized water, 0.5 parts BYK-190 dispersant, 12 parts chemically passivated filler zinc molybdate, and 15 parts sheet-like physical shielding filler glass flakes; 4 parts conductive nanofiller conductive carbon black.

[0055] Group B proportion: Mix 45 parts of phenolic amine modified waterborne curing agent, 10 parts of propylene glycol methyl ether and 18 parts of deionized water.

[0056] Example 8 The difference from Example 1 is as follows: Group A mix: 18 parts deionized water, 1 part BYK-190 dispersant, 6 parts each of chemically passivated filler aluminum tripolyphosphate and zinc phosphate, and 10 parts sericite sheet-like physical shielding filler; 1.5 parts conductive nanofiller fluorinated graphene.

[0057] Group B proportion: Mix 60 parts of phenolic amine modified waterborne curing agent, 6 parts of propylene glycol methyl ether and 12 parts of deionized water.

[0058] Example 9 The difference from Example 1 is as follows: Group A mix: 20 parts deionized water, 1 part BYK-190 dispersant, 8 parts chemically passivated filler aluminum tripolyphosphate, and 10 parts sheet-like physical shielding filler talc; 1 part each of conductive nanofiller fluorinated graphene and conductive carbon black.

[0059] Group B proportion: Mix 50 parts of phenolic amine modified waterborne curing agent, 8 parts of propylene glycol methyl ether and 15 parts of deionized water.

[0060] Example 10 The difference from Example 1 is as follows: Group A mix: 22 parts deionized water, 1 part BYK-190 dispersant, 10 parts chemically passivated filler zinc phosphate, and 5 parts each of sheet-like physical shielding filler sericite and talc; 2 parts conductive nanofiller conductive carbon black.

[0061] Group B proportion: Mix 55 parts of phenolic amine modified waterborne curing agent, 10 parts of propylene glycol methyl ether and 18 parts of deionized water.

[0062] Comparative Example 1 The difference from Example 1 is that no supported nano-corrosion-resistant microcapsules are added to component A, and the vacant parts are filled by an equal amount of self-emulsifying epoxy resin emulsion.

[0063] Comparative Example 2 The difference from Example 1 is that the emulsion prepared in S1 is emulsified using a traditional external emulsifier (such as sodium dodecyl sulfate), rather than the polyetheramine chemically modified self-emulsifying resin described in this invention. Specifically, equal amounts of bisphenol A type epoxy resin (E-51) are mixed with 3% sodium dodecyl sulfate and emulsified under high-speed shear to obtain an emulsion with a solid content of 50%.

[0064] Comparative Example 3 The difference from Example 1 is that: no conductive nanofiller (fluorinated graphene) and chemically passivated filler (aluminum tripolyphosphate) are added to component A, only sheet-like physical shielding filler (10 parts sericite) is retained, and the missing parts are filled by an equal amount of self-emulsifying epoxy resin emulsion.

[0065] Comparative Example 4 The difference from Example 1 is that no sheet-like physical shielding filler (sericite) and chemical passivation filler (aluminum tripolyphosphate) are added to component A. Only conductive nanofiller (1 part of fluorinated graphene) is retained, and the missing part is filled by an equal amount of self-emulsifying epoxy resin emulsion.

[0066] Examples 1-3, 6, 8-10 and Comparative Examples 1-4 were mixed at a mass ratio of component A to component B of 4:1; Example 4 was mixed at a mass ratio of component A to component B of 5:1; Example 5 was mixed at a mass ratio of component A to component B of 3.5:1; and Example 7 was mixed at a mass ratio of component A to component B of 4.5:1. An appropriate amount of deionized water was added to adjust the application viscosity. The mixture was then sprayed onto a sandblasted Q235 carbon steel plate (150mm × 70mm × 1mm) to control the dry film thickness at 80±5μm. After curing at room temperature (25℃) for 7 days, the following performance tests were performed: Adhesion: Tested according to GB / T9286-1998 "Cross-cut test for paint and varnish film", rated from 0 to 5, with 0 being the best.

[0067] Impact resistance: Tested according to GB / T1732-1993 "Determination of impact resistance of paint film", unit is kg·cm.

[0068] Flexibility: Tested according to GB / T1731-1993 "Determination of Flexibility of Paint Film", unit is mm.

[0069] Water resistance: Tested according to GB / T1733-1993 "Test Method for Water Resistance of Paint Film", and observed for blistering, rusting and peeling of the paint film after soaking for 240 hours.

[0070] Salt spray resistance: Tested according to GB / T1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes", and the width of unilateral corrosion (mm) and the time (hours) when the first visible corrosion point appears were recorded.

[0071] Electrochemical impedance spectroscopy (EIS): After immersion in 3.5% NaCl solution for 30 days, the low-frequency (0.01 Hz) impedance modulus was measured |Z|. 0.01Hz The higher the value, the better the protective performance of the coating.

[0072] The performance test results of Examples 1-10 and Comparative Examples 1-4 are shown in Table 1: Table 1 Note: In the table, 1-10 in the number column represent Examples 1-10, and D1-D4 represent Comparative Examples 1-4.

[0073] As can be seen from the data in Table 1, the waterborne epoxy anticorrosive paints prepared in Examples 1-10 of this invention exhibit excellent comprehensive performance: adhesion all reach grade 0-1, impact resistance ≥45 kg·cm, flexibility ≤2 mm, and no abnormalities in water resistance after 240 hours. Particularly in terms of salt spray resistance, the time to the first corrosion point in Examples 1-10 is all above 1380 hours, with Example 5 reaching 1810 hours, far exceeding the industry average (conventional waterborne epoxy coatings typically take 300-500 hours). This indicates that the technical solution of this invention successfully achieves the preparation of a highly corrosion-resistant waterborne epoxy anticorrosive paint. Comparing Example 1 and Comparative Example 1, the only difference is the addition of a loaded nano-corrosion-resistant microcontainer. The results show that the salt spray resistance time of Comparative Example 1 (720 h) decreased by 56.4% compared to Example 1 (1650 h), and the low-frequency impedance modulus decreased from 2.5 × 10⁻⁶. 9 Ω·cm 2 Reduced to 3.5×10 7 Ω·cm 2 The corrosion rate decreased by nearly two orders of magnitude. This fully demonstrates that the pH-responsive nanocontainer designed in this invention can release corrosion inhibitors during the coating's service life, achieving active corrosion protection and self-healing functions, and significantly extending the coating's protective lifespan.

[0074] Comparing Example 1 and Comparative Example 2, Comparative Example 2 used a conventional external emulsifier (sodium dodecyl sulfate) to prepare the emulsion. The results showed that the adhesion of Comparative Example 2 decreased to grade 2, and after 240 hours of water resistance, it exhibited significant bubbling and loss of gloss, with a salt spray resistance time of only 480 hours. This is because the external emulsifier remained in the system after the coating cured, forming hydrophilic channels that allowed moisture and corrosive media to easily penetrate. In contrast, this invention uses a chemically modified polyetheramine self-emulsifying resin, covalently integrating hydrophilic segments into the resin backbone, eliminating the negative impact of small-molecule emulsifiers and significantly improving the intrinsic water resistance and protective performance of the coating.

[0075] Comparing Example 1 with Comparative Example 3 (physical shielding only) and Comparative Example 4 (conductive filler only), the synergistic effect of the ternary composite system can be clearly seen: Comparative Example 3 (sericeous mica only) had a salt spray resistance time of 650 hours and a low-frequency impedance of 1.8 × 10⁻⁶. 7 Ω·cm 2 ; Comparative Example 4 (fluorinated graphene only) had a salt spray resistance time of 890 h and a low-frequency impedance of 5.6 × 10⁻⁶. 7 Ω·cm 2 ; Example 1 (ternary compound): Salt spray resistance time 1650h, low frequency impedance 2.5×10⁻⁶. 9 Ω·cm 2 .

[0076] The performance of Example 1 is far superior to the simple sum of Comparative Examples 3 and 4, demonstrating a significant synergistic effect between the sheet-like physical shielding filler, conductive nanofiller, and chemically passivated filler. The sheet-like filler creates a maze effect to extend the penetration path, the conductive filler disperses the corrosion current and fills the nanoscale pores, and the passivated filler reacts with metal ions to form a dense passivation film. The three work together to construct a multi-dimensional three-dimensional protective network.

[0077] Comparing Examples 1-10, it can be seen that: Nanocontainer dosage: Example 5 (10 parts) showed the best salt spray resistance (1810h), but Example 4 (1 part) also reached 1380h, indicating that the range of 1-10 parts can be effective, and 5-8 parts are preferred to obtain better results.

[0078] The filler ratio: Example 5 (10 parts aluminum tripolyphosphate + 2 parts modified carbon nanotubes + 12 parts sericite) showed the best overall performance, indicating that appropriately increasing the ratio of passivating filler and conductive filler is beneficial to improving corrosion resistance.

[0079] Polyetheramine molecular weight and feed ratio: In this example, a molecular weight of 2000 and a molar ratio of 2:1 were uniformly used. The prepared emulsion exhibited good stability, and the coating showed excellent flexibility and adhesion. Based on the range disclosed in the specification (molecular weight 400-4000, molar ratio 1.5-3:1), those skilled in the art can optimize the parameters through conventional experiments to obtain better results.

[0080] In summary, the waterborne epoxy anticorrosive paint provided by this invention successfully solves the technical problems of poor water resistance and limited anticorrosive function of existing waterborne epoxy coatings through the synergistic effect of a polyetheramine chemically modified self-emulsifying resin, a pH-responsive nano-container loaded with corrosion inhibitors, and a ternary composite system of sheet-like physical shielding filler + conductive nano-filler + chemically passivated filler. Example data shows that the salt spray resistance of the coating of this invention can reach over 1800 hours, and the low-frequency impedance modulus is as high as 10. 9 Ω·cm 2 With orders of magnitude larger and excellent overall performance, it possesses extremely high industrial application value and market prospects.

[0081] It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-based epoxy anti-corrosion paint, characterized in that, The anti-corrosion paint is a two-component system, including component A and component B; Component A includes a self-emulsifying epoxy resin emulsion, a supported nano-corrosion-resistant microcontainer, and a functional filler compound system. Component B includes a water-based epoxy curing agent; The self-emulsifying epoxy resin emulsion is formed by reacting bisphenol A type epoxy resin with polyetheramine to obtain a polymer with an amphiphilic block structure, and then dispersing it in water by a phase inversion method. The loaded nano-corrosion-resistant microcontainer is a hollow cerium dioxide microsphere loaded with a corrosion inhibitor, and the surface of the hollow cerium dioxide microsphere is coated with a polymer encapsulation layer. The functional filler compound system includes at least a mixture of sheet-like physical shielding fillers, conductive nanofillers, and chemically passivated fillers.

2. The water-based epoxy anticorrosive paint according to claim 1, characterized in that, The polyetheramine is a polyether diamine with a number-average molecular weight of 400-4000; The molar ratio of the bisphenol A type epoxy resin to the polyetheramine in the chain extension reaction is (1.5-3):

1.

3. The water-based epoxy anticorrosive paint according to claim 1, characterized in that, The corrosion inhibitor includes organic corrosion inhibitors and / or inorganic corrosion inhibitors; The organic corrosion inhibitor is benzotriazole; The inorganic corrosion inhibitor is at least one of molybdate or cerium salt; The polymer encapsulation layer is a polydopamine layer.

4. The water-based epoxy anticorrosive paint according to claim 1, characterized in that, The sheet-like physical shielding filler includes at least one of sericite, talc, and glass flakes; The conductive nanofiller includes at least one of fluorinated graphene, conductive carbon black, and modified carbon nanotubes. The chemically passivated filler includes at least one of aluminum tripolyphosphate, zinc phosphate, and zinc molybdate.

5. The water-based epoxy anticorrosive paint according to claim 1, characterized in that, Component A comprises, by weight: 30-60 parts of self-emulsifying epoxy resin emulsion (in solids), 1-10 parts of load-bearing nano-corrosion-resistant micro-containers, 5-20 parts of sheet-like physical shielding filler, 0.5-5 parts of conductive nano-filler, 5-15 parts of chemically passivated filler, 0-5 parts of additives, and 10-30 parts of deionized water. Component B comprises: 40-70 parts of water-based epoxy curing agent, 0-15 parts of co-solvent and 10-30 parts of deionized water; The mass mixing ratio of component A to component B is 100:(15-40).

6. A method for preparing a water-based epoxy anticorrosive paint as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Under inert gas protection, bisphenol A type epoxy resin and polyetheramine are mixed and reacted at 70-120℃ for 1-4 hours to obtain polyetheramine modified epoxy resin intermediate; after cooling, deionized water containing organic acid is slowly added under stirring, and self-emulsifying epoxy resin emulsion is obtained by phase inversion method. S2. Provide hollow cerium dioxide microspheres, load a corrosion inhibitor into the hollow cavity of the hollow cerium dioxide microspheres, and then coat the surface of the microspheres with a polymer encapsulation layer to obtain a loaded nano-corrosion-resistant microcontainer; S3. Mix deionized water, additives, chemical passivation fillers and sheet-like physical shielding fillers according to the formula, and disperse and grind them until the fineness is ≤50 micrometers; then add the self-emulsifying epoxy resin emulsion prepared in S1, the supported nano-corrosion-resistant micro-container prepared in S2 and the conductive nano-filler in sequence, stir evenly, filter, and obtain component A. S4. Mix the water-based epoxy curing agent, co-solvent, and deionized water according to the specified ratio, stir evenly, and filter to obtain component B.

7. The method for preparing the waterborne epoxy anticorrosive paint according to claim 6, characterized in that, The molar ratio of bisphenol A epoxy resin to polyetheramine in S1 is (1.5-3):1; The polyetheramine is a polyether diamine with a number average molecular weight of 400-4000; the solid content of the self-emulsifying epoxy resin emulsion is 40-60%.

8. The method for preparing the waterborne epoxy anticorrosive paint according to claim 6, characterized in that, The step S2, which involves loading the corrosion inhibitor into the hollow cavity of the hollow cerium dioxide microspheres, includes the following steps: Hollow cerium dioxide microspheres are dispersed in a solution containing a corrosion inhibitor and loaded by vacuum impregnation or high-pressure adsorption. The process of coating the microspheres with a polymer encapsulation layer includes the following steps: The microspheres loaded with corrosion inhibitor were dispersed in a weakly alkaline buffer solution of dopamine and stirred for 6-24 hours to allow dopamine to oxidize and self-polymerize on the surface of the microspheres to form a polydopamine layer. Then, the microspheres were separated, washed, and dried.

9. The method for preparing the waterborne epoxy anticorrosive paint according to claim 6, characterized in that, In step S3, the dispersion and grinding to a fineness of ≤50 micrometers is carried out by a high-speed disperser and grinding equipment. The mixing process is carried out at a low speed of 20-80 rpm to avoid damaging the structure of the nanofiller.

10. An application of a water-based epoxy anticorrosive paint, characterized in that, Application of the waterborne epoxy anticorrosive paint according to any one of claims 1-5 or the waterborne epoxy anticorrosive paint prepared by the preparation method according to any one of claims 6-9 in the field of metal substrate corrosion protection; The application involves mixing component A and component B, applying the mixture to the surface of a metal substrate, and curing it to form an anti-corrosion coating; the metal substrate includes at least one of carbon steel, cast iron, and aluminum alloy; the application areas include anti-corrosion protection for bridges, ships, pipelines, containers, and marine engineering equipment.

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