High-corrosion-resistance nano graphene coating and preparation method thereof

Abstract

The invention relates to the technical field of anticorrosive coatings, and discloses a high-corrosion-resistance nano graphene coating and a preparation method thereof, the coating comprises a component A and a component B, the component A comprises 10-30 parts of epoxy resin, 2-10 parts of graphene slurry, 20-70 parts of zinc powder, 5-40 parts of ferrophosphorus powder, 5-40 parts of barium sulfate and an auxiliary agent; and the component B is 10-30 parts of a modified alicyclic amine curing agent. The preparation method comprises the following steps: stage 1, shearing and dispersing epoxy resin, graphene slurry and zinc powder at a high speed at 45-60 DEG C to construct a conductive skeleton; stage 2, cooling to 25-30 DEG C, and adding ferrophosphorus powder, barium sulfate and a rheological additive at a low speed to obtain a component A; finally, mixing the component A with the component B; according to the invention, a two-stage process of high-temperature anchoring and low-temperature locking is adopted, the conductive filler is dispersed, and the anti-settling problem of the high-density filler is solved, so that the corrosion resistance and storage stability of the coating are improved.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, specifically to a highly corrosion-resistant nano-graphene coating and its preparation method. Background Technology

[0002] Epoxy resin coatings are widely used for long-term protection of steel structures in harsh corrosive environments such as marine engineering, bridges, and petrochemicals due to their excellent adhesion, mechanical properties, and chemical resistance. In heavy-duty anti-corrosion coating systems, zinc-rich primers are a traditional solution that relies on high zinc powder content to provide cathodic protection (i.e., electrochemical corrosion protection).

[0003] However, existing anti-corrosion coating technologies still have shortcomings. First, traditional zinc-rich primers rely excessively on high zinc powder content, which not only increases costs but also leads to rapid electrochemical consumption of zinc powder and relatively insufficient physical shielding performance of the coating. When the coating porosity is high, corrosive media can easily penetrate, resulting in limited long-term protective capabilities.

[0004] Secondly, to improve coating performance, novel nanomaterials such as graphene have been attempted to be introduced into anti-corrosion coatings. However, graphene, with its high specific surface area and strong van der Waals forces, is prone to agglomeration in resin bases and is difficult to disperse effectively. Simultaneously, high-density zinc powder is also difficult to distribute uniformly in high-viscosity epoxy resins. The shear force provided by conventional room-temperature stirring or simple dispersion processes is insufficient to overcome these agglomeration forces, preventing graphene and zinc powder from forming a uniform and complete three-dimensional conductive network, thus limiting the electrochemical performance of the coating.

[0005] Furthermore, coating compositions containing high-density fillers (such as zinc powder, ferrophosphorus powder, etc.) have inherent defects in storage stability. During long-term storage of the coating's base components, these high-density fillers are prone to settling under gravity. Settling forms dense, hard precipitates that are difficult to redisperse evenly through conventional stirring before use. This not only inconveniences construction but also leads to uneven composition of the actual coating, resulting in reduced corrosion resistance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a highly corrosion-resistant nano-graphene coating and its preparation method, which solves the problems of poor synergistic effect of electrochemical protection and physical shielding and limited comprehensive corrosion resistance of existing anti-corrosion coatings; at the same time, it solves the problem that graphene with high specific surface area and high-density zinc powder are difficult to disperse uniformly in resin and cannot form an efficient conductive network; and overcomes the problems of easy hard sedimentation and poor storage stability of the base material component containing high-density filler.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a highly corrosion-resistant nano-graphene coating and its preparation method.

[0008] In a first aspect, the present invention provides a highly corrosion-resistant nano-graphene coating, which adopts the following technical solution: A highly corrosion-resistant nano-graphene coating comprises component A and component B. Component A comprises the following raw materials in parts by weight: 10-30 parts epoxy resin; 2-10 parts graphene slurry; 20-70 parts zinc powder; 5-40 parts ferrophosphorus powder; 5-40 parts barium sulfate; 0.1-1 part dispersant; 0.1-0.8 parts wetting agent; 0.1-0.6 parts defoamer; 0.5-2 parts thickener; and 0.5-2 parts anti-settling agent. Component B comprises the following raw material in parts by weight: 10-30 parts modified cycloaliphatic amine curing agent.

[0009] By adopting the above technical solution, the coating composition of the present invention provides a material basis for achieving a dual synergistic anti-corrosion mechanism through the specific compounding of components.

[0010] First, the composition uses graphene slurry and zinc powder together as conductive functional fillers. The excellent conductivity and large specific surface area of ​​graphene nanosheets allow them to act as conductive nodes in the epoxy resin matrix, overlapping with zinc powder particles to construct a three-dimensional conductive network. This structure improves the electrochemical utilization efficiency of zinc powder, laying the foundation for achieving efficient and long-lasting cathodic protection (electrochemical corrosion prevention) after coating curing.

[0011] Secondly, the composition uses ferric phosphorus powder and barium sulfate as shielding fillers. These two chemically inert fillers are used to fill the gaps formed by the aforementioned conductive network. By forming a dense physical accumulation in the coating, they effectively increase the density of the coating and prolong the path of corrosive media (such as water, oxygen, and chloride ions) to penetrate to the substrate surface, thereby providing a physical shielding effect (physical corrosion protection).

[0012] The formulation design of this invention enables conductive fillers (graphene, zinc powder) and shielding fillers (iron phosphate powder, barium sulfate) to perform their respective functions under specific preparation processes. The resulting coating combines highly efficient electrochemical activity with dense physical shielding, achieving a synergistic effect of the two anti-corrosion mechanisms.

[0013] Preferably, component A comprises the following raw materials in parts by weight: 15-25 parts epoxy resin; 4-8 parts graphene slurry; 30-60 parts zinc powder; 15-30 parts ferrophosphorus powder; 15-30 parts barium sulfate; 0.3-0.8 parts dispersant; 0.2-0.7 parts wetting agent; 0.2-0.5 parts defoamer; 0.8-1.7 parts thickener; and 0.8-1.7 parts anti-settling agent; and component B comprises the following raw material in parts by weight: 15-25 parts modified cycloaliphatic amine curing agent.

[0014] By adopting the above technical solution, the ratio between the components is further optimized, so that the construction of the conductive network and the filling of the physical shielding are in better balance, thereby ensuring the construction performance while optimizing the overall anti-corrosion effect of the coating.

[0015] Preferably, in the graphene slurry, the average thickness of the graphene nanosheets is less than 10 nm, and the average sheet diameter is 5-25 µm.

[0016] By adopting the above technical solution, the defined graphene has a high aspect ratio and a large specific surface area, which is conducive to forming an efficient overlap with zinc powder at a low addition amount, constructing a more complete conductive network, and enhancing the physical shielding performance of the coating.

[0017] Preferably, the zinc powder is spherical zinc powder with an average particle size of 3-5µm; the epoxy resin is bisphenol A type liquid epoxy resin.

[0018] By adopting the above technical solution, spherical zinc powder with a specific particle size has good dispersibility and stacking properties, making it easy to form conductive pathways; bisphenol A type liquid epoxy resin as the base material has excellent mechanical properties, chemical resistance and adhesion to the substrate, providing a solid performance foundation for the coating.

[0019] Preferably, the dispersant is selected from polyurethane dispersants, polyacrylate dispersants, or copolymers with anchoring groups; the wetting agent is selected from polyether-modified polysiloxanes or acetylene glycol surfactants; the defoamer is selected from modified polysiloxane defoamers, mineral oil defoamers, or polyether defoamers; and the thickener and the anti-settling agent are selected from one or a combination of several of fumed silica, organobentonite, polyamide wax, or hydrogenated castor oil derivatives.

[0020] By adopting the above technical solution, additives with good compatibility and well-defined functions with the epoxy resin system were selected. Specific combinations of dispersants and wetting agents are key to achieving efficient dispersion and stability of conductive fillers in stage one (high-temperature anchoring stage); specific combinations of thickeners and anti-settling agents ensure viscosity locking in stage two (low-temperature filling stage) and system stability during storage, preventing high-density filler sedimentation.

[0021] Secondly, the present invention provides a method for preparing a highly corrosion-resistant nano-graphene coating, employing the following technical solution: A method for preparing a highly corrosion-resistant nano-graphene coating includes the following steps: (1) Stage 1: Add 10-30 parts by weight of epoxy resin, 0.1-1 parts by weight of dispersant, and 0.1-0.8 parts by weight of wetting agent into the kettle and mix; start heating and control the material temperature to 45-60℃; add 2-10 parts by weight of graphene slurry and perform high-speed shear dispersion; maintain the temperature and add 20-70 parts by weight of zinc powder and continue high-speed shear dispersion. (2) Stage 2: Stop heating and cool the material to 25-30℃; switch to low speed stirring, add 5-40 parts by weight of ferrophosphorus powder and 5-40 parts by weight of barium sulfate; keep stirring at low speed, add 0.1-0.6 parts by weight of defoamer, 0.5-2 parts by weight of thickener and 0.5-2 parts by weight of anti-settling agent, mix evenly to obtain component A; (3) Mix the A component obtained in step (2) with the B component to obtain a highly corrosion-resistant nano-graphene coating.

[0022] By adopting the above technical solution, the present invention provides a two-stage, step-by-step temperature-controlled preparation process. This process design solves the technical problem that it is difficult to achieve efficient dispersion and stable storage of high-density conductive fillers (zinc powder, graphene) and inert shielding fillers in epoxy resin at the same time.

[0023] The core mechanism of this process lies in: Stage 1 (Conductive Framework Anchoring): Under high-temperature conditions (45-60℃), the viscosity of the epoxy resin system decreases. At this point, wetting agents and dispersants are added, and high-speed shearing is applied, providing excellent fluid conditions for the subsequent dispersion of functional fillers. In this low-viscosity system, the high mechanical energy provided by high-speed shearing effectively overcomes the high specific surface area and van der Waals forces of graphene nanosheets, allowing for their complete exfoliation; simultaneously, it deagglomerates high-density zinc powder particles. Under the synergistic effect of thermal energy and high shear energy, graphene and zinc powder are forcibly and uniformly anchored in the resin matrix, pre-constructing a uniform and dense three-dimensional conductive network framework.

[0024] Phase Two (Viscosity Lock-in Filling): First, the material is cooled (25-30℃), a crucial step for viscosity lock-in. Cooling causes the resin system's viscosity to rise, providing a high-viscosity foundation for the subsequent addition of rheology modifiers (thickeners, anti-settling agents). Then, low-speed stirring is employed. This speed gently mixes the shielding fillers and additives, such as iron phosphate powder and barium sulfate, evenly, while avoiding damage to the conductive framework formed in Phase One and the thixotropic structure to be built by high-speed shearing. Finally, the added thickener and anti-settling agent construct an effective thixotropic network under low temperature, high viscosity, and low shear conditions, stably suspending the high-density filler anchored in Phase One, achieving excellent storage stability.

[0025] Stage 3 (Mixed Curing): In step (3), the prepared component A is mixed with component B (modified alicyclic amine curing agent) to initiate a cross-linking curing reaction between epoxy groups and active hydrogen of amines. The final coating has both the complete conductive network formed in stage 1 (providing cathodic protection) and the dense shielding filler filled in stage 2 (providing physical shielding), thus achieving the synergistic effect of dual anti-corrosion mechanism.

[0026] Preferably, in step (1), the material temperature is controlled to 52.5-60℃, and the high-speed shear dispersion speed is 2250-2500rpm.

[0027] By adopting the above technical solution, this temperature control and rotation speed range is the optimal process window for achieving efficient dispersion and anchoring of graphene and zinc powder, ensuring the construction quality of the conductive framework.

[0028] Preferably, in step (1), after adding graphene slurry, high-speed shear dispersion is performed for 20-30 minutes; after adding zinc powder, high-speed shear dispersion is performed for another 30-40 minutes.

[0029] By adopting the above technical solution, sufficient dispersion time is ensured, allowing the graphene nanosheets to be fully exfoliated and form a tight bond with the zinc powder particles, thus ensuring the integrity of the conductive path.

[0030] Preferably, in step (2), the speed of the low-speed stirring is 800-1000 rpm.

[0031] By adopting the above technical solution, this speed range provides sufficient hybrid power, which can make the inert filler and rheology modifier mix evenly, while avoiding the damage of the thixotropic structure to excessive shear, and is the ideal stirring condition for achieving viscosity lock.

[0032] Preferably, in step (2), after adding ferric phosphorus powder and barium sulfate, stir at low speed for 15-20 minutes; after adding defoamer, thickener and anti-settling agent, continue stirring at low speed for 15-20 minutes.

[0033] By adopting the above technical solution, the order of addition and mixing time of each material in stage two are clarified, ensuring that the inert filler is wetted first, and then the rheology modifier plays a role in the uniform system, which helps to form a stable and uniform component A base material.

[0034] This invention provides a highly corrosion-resistant nano-graphene coating and its preparation method. It possesses the following beneficial effects: 1. This invention achieves a dual synergistic effect of electrochemical (cathode protection) and physical shielding corrosion protection by conductively compounding graphene slurry with zinc powder and supplementing it with ferric phosphorus powder and barium sulfate as inert shielding fillers. The high conductivity of graphene and the electrochemical activity of zinc powder construct a highly efficient conductive network, while the dense packing of inert fillers extends the penetration path of corrosive media. This gives the coating both high electrochemical activity and excellent physical shielding properties, improving the overall corrosion resistance and service life of the coating.

[0035] 2. This invention employs a combination of high temperature (45-60℃) and high-speed shearing. The high temperature reduces the viscosity of the epoxy resin matrix, providing an ideal fluid environment for the high-speed shearing dispersion of graphene and zinc powder. This ensures that the high specific surface area graphene and high density zinc powder can be fully deagglomerated and uniformly anchored in the resin, thereby constructing a uniform and complete three-dimensional conductive network framework, providing a foundation for achieving cathodic protection.

[0036] 3. This invention employs a viscosity-locking process involving cooling (25-30℃) and low-speed stirring. By first cooling the system to restore its viscosity, and then adding thickeners and anti-settling agents for low-speed mixing, a stable thixotropic structure can be constructed without disrupting the conductive network already formed in stage one. This solves the technical problem of hard sedimentation that easily occurs when high-density fillers (such as zinc powder and ferrophosphorus powder) are stored in component A of the base material for a long time, ensuring the storage stability of component A of the coating. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Examples 1-3: Example 1: This embodiment provides a method for preparing a highly corrosion-resistant nano-graphene coating. The components (parts by weight) of component A (base material) are: 30 parts epoxy resin, 2 parts graphene slurry, 20 parts zinc powder, 40 parts ferric phosphorus powder, 40 parts barium sulfate, 0.1 parts dispersant, 0.1 parts wetting agent, 0.1 parts defoamer, 0.5 parts thickener, and 0.5 parts anti-settling agent.

[0039] The specific preparation steps for component A include: Phase 1 (Conductive framework anchoring): Add 30 parts epoxy resin, 0.1 parts dispersant, and 0.1 parts wetting agent to a jacketed dispersion vessel. Turn on low-speed stirring (400 rpm) and start the heating system to control the material temperature to 45°C.

[0040] Add 2 parts of graphene slurry at 45°C and low speed stirring, then disperse at high speed (2000 rpm) for 20 minutes.

[0041] Maintain 45°C and high-speed shearing (2000 rpm), add 20 parts zinc powder, and continue dispersing for 30 minutes.

[0042] Phase 2 (Viscosity Lock-in Filling): Stop heating and turn on the jacket cooling system to cool the material temperature to 25°C.

[0043] At 25°C, switch to low speed stirring (800 rpm), add 40 parts of ferric phosphorus powder and 40 parts of barium sulfate, and stir for 15 minutes.

[0044] Keep stirring at a low speed (800 rpm), add 0.1 parts of defoamer, 0.5 parts of thickener and 0.5 parts of anti-settling agent, continue stirring for 15 minutes to mix evenly, then discharge to obtain component A.

[0045] Preparation of Component B (Curing Agent): In this embodiment, component B (curing agent) was prepared by packaging 30 parts of modified cycloaliphatic amine curing agent separately, and its amount matched the amount of epoxy resin in component A.

[0046] Final preparation (mixing) of the coating: When using, the above-prepared component A and component B are mixed in a ratio of A:B = 133.3:30 (by weight), and stirred evenly using a power stirrer to obtain a highly corrosion-resistant nano-graphene coating.

[0047] Example 2: This embodiment provides a method for preparing a highly corrosion-resistant nano-graphene coating. The components (parts by weight) of component A (base material) are: 20 parts epoxy resin, 6 parts graphene slurry, 45 parts zinc powder, 22.5 parts ferric phosphorus powder, 22.5 parts barium sulfate, 0.55 parts dispersant, 0.45 parts wetting agent, 0.35 parts defoamer, 1.25 parts thickener, and 1.25 parts anti-settling agent.

[0048] The specific preparation steps for component A include: Phase 1 (Conductive framework anchoring): Add 20 parts epoxy resin, 0.55 parts dispersant, and 0.45 parts wetting agent to a jacketed dispersion vessel. Turn on low-speed stirring (400 rpm) and start the heating system to control the material temperature to 52.5℃.

[0049] Add 6 parts of graphene slurry at 52.5℃ and low speed stirring, then disperse at high speed (2250 rpm) for 25 minutes.

[0050] Maintain 52.5°C and high-speed shearing (2250 rpm), add 45 parts zinc powder, and continue dispersing for 35 minutes.

[0051] Phase 2 (Viscosity Lock-in Filling): Stop heating and turn on the jacket cooling system to cool the material temperature to 25°C.

[0052] At 25°C, switch to low speed stirring (800 rpm), add 22.5 parts of ferrophosphorus powder and 22.5 parts of barium sulfate, and stir for 15 minutes.

[0053] Keep stirring at a low speed (800 rpm), add 0.35 parts of defoamer, 1.25 parts of thickener and 1.25 parts of anti-settling agent, and continue stirring for 15 minutes to mix evenly. Discharge to obtain component A.

[0054] Preparation of Component B (Curing Agent): In this embodiment, component B (curing agent) was prepared by packaging 20 parts of modified cycloaliphatic amine curing agent separately, and its amount matched the amount of epoxy resin in component A.

[0055] Final preparation (mixing) of the coating: When using, the above-prepared component A and component B are mixed in a ratio of A:B = 119.9:20 (by weight), and stirred evenly using a power stirrer to obtain a highly corrosion-resistant nano-graphene coating.

[0056] Example 3: This embodiment provides a method for preparing a highly corrosion-resistant nano-graphene coating. The components (parts by weight) of component A (base material) are: 10 parts epoxy resin, 10 parts graphene slurry, 70 parts zinc powder, 5 parts ferric phosphorus powder, 5 parts barium sulfate, 1 part dispersant, 0.8 parts wetting agent, 0.6 parts defoamer, 2 parts thickener, and 2 parts anti-settling agent.

[0057] The specific preparation steps for component A include: Phase 1 (Conductive framework anchoring): Add 10 parts epoxy resin, 1 part dispersant, and 0.8 parts wetting agent to a jacketed dispersion vessel. Turn on low-speed stirring (400 rpm) and start the heating system to control the material temperature to 60°C.

[0058] Add 10 parts of graphene slurry at 60°C and low speed stirring, then disperse at high speed (2500 rpm) for 30 minutes.

[0059] Maintain 60°C and high-speed shearing (2500 rpm), add 70 parts zinc powder, and continue dispersing for 40 minutes.

[0060] Phase 2 (Viscosity Lock-in Filling): Stop heating and turn on the jacket cooling system to cool the material temperature to 30°C.

[0061] At 30°C, switch to low speed stirring (1000 rpm), add 5 parts ferric phosphorus powder and 5 parts barium sulfate, and stir for 20 minutes.

[0062] Keep stirring at a low speed (1000 rpm), add 0.6 parts of defoamer, 2 parts of thickener and 2 parts of anti-settling agent, continue stirring for 20 minutes to mix evenly, then discharge to obtain component A.

[0063] Preparation of Component B (Curing Agent): In this embodiment, component B (curing agent) was prepared by packaging 10 parts of modified cycloaliphatic amine curing agent separately, and its amount matched the amount of epoxy resin in component A.

[0064] Final preparation (mixing) of the coating: When using, the above-prepared component A and component B are mixed in a ratio of A:B = 106.4:10 (by weight), and stirred evenly using a power stirrer to obtain a highly corrosion-resistant nano-graphene coating.

[0065] Comparative Examples 1-4: Comparative Example 1: The same formulation (components A and B) as in Example 2 was used. The difference was that the preparation process of component A was as follows: at room temperature (25°C), all raw materials of component A in Example 2 (including epoxy resin, graphene slurry, zinc powder, ferric phosphorus powder, barium sulfate, and all additives) were added to a dispersion vessel at once and mixed and dispersed at high speed (2250 rpm) for 60 minutes. Everything else was the same.

[0066] Comparative Example 2: The same formulation (components A and B) as in Example 2 was used. The difference was that although the preparation of component A was carried out using a stepwise process, the entire process was conducted at room temperature (25°C), excluding the heating step (52.5°C) in stage one and the cooling step before stage two. Everything else was the same.

[0067] Comparative Example 3: The same formulation (components A and B) as in Example 2 was used. The difference was that the preparation method for component A lacked the locking cooling step. Specifically, the preparation in stage one (heating to 52.5°C for anchoring) was the same as in Example 2; however, in stage two, the ferrophosphorus powder, barium sulfate, and subsequent additives were added while maintaining a temperature of 52.5°C and stirring at a low speed, without performing the cooling to 25°C step. Everything else was the same.

[0068] Comparative Example 4: The same formulation (components A and B) as in Example 2 was used. The difference was that the preparation of component A involved the reverse order of addition. Specifically, in stage one (heating to 52.5°C and high-speed shearing at 2250 rpm), 22.5 parts of ferrophosphorus powder and 22.5 parts of barium sulfate were added; in stage two (cooling to 25°C and low-speed stirring at 800 rpm), 6 parts of graphene slurry and 45 parts of zinc powder were added. All other steps remained the same.

[0069] Test Example 1-3: Test Example 1: Experimental instruments and apparatus: A high-resistance meter (Keithley 6517B or equivalent) and a homemade PTFE test mold were used. The mold is a rectangular groove with internal dimensions of 50.0mm × 10.0mm × 10.0mm. Standard copper electrodes (10.0mm × 10.0mm cross-section) are embedded at both ends of the mold for applying voltage and measuring resistance.

[0070] Experimental steps: Take the A component base material samples prepared in Examples 1-3 and Comparative Examples 1-4 respectively, and place them in a constant temperature environment of (25±1)℃ for 2 hours.

[0071] Fill the polytetrafluoroethylene test mold with the sample of component A to be tested, ensuring that the base material fills the cavity inside the mold and is in close contact with the copper electrodes at both ends.

[0072] Use a scraper to smooth the sample surface above the mold and remove excess base material.

[0073] Connect the two test electrodes of the high resistance meter to the copper electrodes at both ends of the mold.

[0074] Set the test conditions, apply a 100V DC voltage, and after the reading stabilizes, record the resistance value (R) of component A base material.

[0075] According to the formula Calculate the volume resistivity of the base material ( Among them, the electrode spacing Electrode cross-sectional area .

[0076] Each sample was measured three times, and the average value of the data was recorded.

[0077] Experimental data: Table 1: Volume resistivity of Component A (Uncured) Note: 10 10 Values ​​of 100 and above are close to the insulation limit of the matrix resin.

[0078] The data in Table 1 show that the volume resistivity of the A component base material (uncured) prepared in Examples 1-3 is lower than that of all comparative examples, with the difference reaching several orders of magnitude.

[0079] The low resistivity of component A even before curing demonstrates that, under the preparation process of this invention, conductive fillers such as graphene and zinc powder have formed an effective and continuous conductive pathway in component A.

[0080] Both the A component base material of Comparative Example 1 (all components mixed at once) and Comparative Example 2 (stepwise mixing at room temperature) exhibited high insulation, indicating that conventional processes cannot form a conductive network before curing, and the conductive filler is only in a dispersed state.

[0081] The resistivity of Comparative Example 3 (with inert filler added at high temperature) was much higher than that of Example 2, demonstrating that the cooling step in Stage 2 (i.e., increasing the viscosity of the system) was necessary to protect the conductive framework formed in Stage 1 from subsequent impact damage.

[0082] Comparative Example 4 (with the reverse feeding order) also exhibited high insulation, further confirming the necessity of prioritizing the construction of the graphene and zinc framework.

[0083] The test results confirm the process mechanism of the present invention: the key to achieving pre-conductivity of the A component base material is to preferentially construct a conductive network by heating and high shear, and then fill the network with inert filler by cooling and low shear while maintaining the integrity of the network.

[0084] Test Example 2: Experimental instruments and methods: Constant temperature drying oven: temperature control accuracy (50±2)℃; Stormer Viscometer: used to measure KU value; metal scraper; standard 1L tin can.

[0085] Experimental steps: Take 1L of each of the A component base material prepared in Examples 1-3 and Comparative Examples 1-4, pack them into tin cans and seal them; The initial viscosity (KU value) of each sample was measured using a Stormer viscometer at (25±1)℃. Place the sealed sample container in a constant temperature oven at (50±2)℃ for 30 days; After 30 days, the sample container was removed and allowed to cool naturally for 24 hours at (25±1)℃. Open the can lid and use a Stormer viscometer to measure the viscosity (KU value) after storage, and calculate the viscosity change. Use a metal scraper to insert into the bottom of the tank to assess the state of the sediment, especially whether there is hard sediment, i.e., dense precipitate that cannot be easily redispersed by conventional stirring.

[0086] Experimental data: Table 2: Results of Accelerated Storage Stability Test of Component A Base Material The data in Table 2 show that after accelerated storage at 50°C for 30 days, the viscosity of the A component base material in Examples 1-3 changed little and no hard sedimentation occurred. Only in Example 3 with a high filler content did slight soft sedimentation occur, indicating that the system has excellent storage stability.

[0087] In contrast, Comparative Example 1 (one-time mixing), Comparative Example 2 (room temperature stepwise mixing), and Comparative Example 4 (reverse feeding) all showed viscosity increases and severe hard sedimentation. This indicates that under conventional processes, high-density zinc powder agglomerates and settles during storage, forming a dense, irreversible precipitate layer.

[0088] The settling condition of Comparative Example 3 (with inert filler added at high temperature) was worse than that of Example 2, demonstrating the necessity of the cooling step in Stage Two for stabilizing the system. If subsequent fillers are added under high temperature and low viscosity conditions without cooling, the suspension structure formed in Stage One will be destroyed, leading to a decrease in system stability.

[0089] Test results confirm that the preparation process of this invention, through thermodynamic anchoring in stage one and viscosity locking in stage two, pre-constructs a stable rheological structure with a yield value in the A-component base material. This structure is sufficient to effectively suspend high-density conductive fillers under high-temperature storage conditions, inhibiting their sedimentation and aggregation, thereby ensuring the storage stability of the A-component base material.

[0090] Test Example 3: Sample preparation: Take the A components prepared in Examples 1-3 and Comparative Examples 1-4 respectively, and mix them with their corresponding B components (curing agents) according to the A / B weight ratio set in the formula; Mix thoroughly with a power mixer (3-5 minutes), then let stand and mature for 15 minutes. The mixed coating is applied to Q235 steel plate using an air spraying method. The steel plate substrate has been pre-sandblasted to meet the Sa2.5 standard, with a roughness of [missing information]. It is 40-60µm; Curing time was 7 days under standard environmental conditions (temperature 25℃, relative humidity 50%). The dry film thickness (DFT) was controlled within the range of (75±5) µm using a coating thickness gauge.

[0091] Experimental methods and instruments: dry film resistivity Instrument: Four-probe tester.

[0092] Method: The volume resistivity of the paint film was measured and recorded on the surface of a 7-day cured sample. ).

[0093] Electrochemical impedance spectroscopy (EIS) Instrument: Electrochemical workstation (three-electrode system).

[0094] Method: The prepared coated sample was used as the working electrode, the saturated calomel electrode (SCE) as the reference electrode, and a platinum sheet as the counter electrode. Tests were performed in a 3.5 wt% NaCl solution.

[0095] Parameters: Test frequency range 100kHz to 0.01Hz. Record the low-frequency impedance modulus at 0.01Hz after the coating has been immersed for 24 hours.

[0096] Neutral Salt Spray Test (NSS) Standard: Conducted in accordance with GB / T10125 "Artificial Atmosphere Corrosion Test - Salt Spray Test".

[0097] Method: Use a scribing tool to make an X-shaped scratch in the center of the sample, extending to the substrate. Place the sample in a neutral salt spray test chamber and spray continuously.

[0098] Parameter: Record the maximum corrosion spread width (mm) on both sides of the scratch after 1000 hours.

[0099] Experimental data: Table 3: Comprehensive Test Data of Cured Coating Film Performance The data in Table 3 comprehensively reflect the impact of the process of this invention on the final coating film performance.

[0100] First, the dry film resistivity data show that the volume resistivity of the coating film in Examples 1-3 is all below 10. 4 The resistivity of Ω·cm indicates that the conductive network formed in component A is maintained after curing, providing the electrochemical basis for cathodic protection in the paint film. The resistivity of comparative examples 1, 2, and 4 is close to 10⁻⁶. 10 The resistivity is on the order of Ω·cm, exhibiting insulating properties and lacking electrochemical activity. The resistivity of Comparative Example 3 is much higher than that of Example 2, confirming the necessity of the cooling step in Stage Two for protecting the conductive network structure from damage.

[0101] Secondly, the EIS low-frequency impedance modulus reflects the physical shielding performance of the varnish film. Examples 1 and 2 both maintained 10... 9 The high impedance on the order of Ω·cm indicates that the process of this invention does not compromise the compactness of the system while constructing the conductive network. The processes of Comparative Examples 1, 2, and 4 result in uneven filler dispersion or agglomeration, numerous paint film defects, and low impedance (10 Ω·cm). 6(on the order of Ω·cm).

[0102] Finally, the neutral salt spray test results verified the comprehensive protective effect. The scratch corrosion width of Examples 1-3 was controlled below 2 mm, which was better than all comparative examples. This is attributed to the fact that the coating film of the examples simultaneously possesses high physical shielding (high EIS impedance) and electrochemical activity (low resistivity), i.e., a dual function of shielding and cathodic protection. The comparative examples, on the other hand, experienced rapid corrosion propagation due to the lack of an effective conductive network (inability to provide cathodic protection) or physical defects in the coating film (low impedance).

[0103] Test results confirm that the two-stage temperature control process of this invention is the key to achieving high-performance anti-corrosion coatings. This process ensures the effective construction of the conductive filler network and the shielding filler structure.

Claims

1. A high corrosion resistant nanographene coating, characterized by, The A component and the B component are mixed to prepare the high corrosion-resistant nanographene coating. The A component comprises the following raw materials by weight: epoxy resin 10-30 parts; graphene paste 2-10 parts; zinc powder 20-70 parts; phosphorus iron powder 5-40 parts; barium sulfate 5-40 parts; dispersant 0.1-1 part; wetting agent 0.1-0.8 part; defoaming agent 0.1-0.6 part; thickening agent 0.5-2 parts; anti-settling agent 0.5-2 parts; The B component comprises the following raw materials by weight: modified alicyclic amine curing agent 10-30 parts.

2. The high anticorrosive nano-graphene coating according to claim 1, characterized in that, Preferably, the A component comprises the following raw materials by weight: epoxy resin 15-25 parts; graphene paste 4-8 parts; zinc powder 30-60 parts; phosphorus iron powder 15-30 parts; barium sulfate 15-30 parts; dispersant 0.3-0.8 parts; wetting agent 0.2-0.7 parts; defoaming agent 0.2-0.5 parts; thickening agent 0.8-1.7 parts; anti-settling agent 0.8-1.7 parts; The B component comprises the following raw materials by weight: modified alicyclic amine curing agent 15-25 parts.

3. The high corrosion resistant nano-graphene coating according to claim 1, characterized in that, In the graphene paste, the average thickness of graphene nanosheets is less than 10 nm, and the average flake diameter is 5-25 µm.

4. The high corrosion resistant nano-graphene coating of claim 1, wherein, The zinc powder is spherical zinc powder with an average particle size of 3-5 µm; the epoxy resin is a liquid bisphenol A type epoxy resin.

5. The high corrosion resistant nano-graphene coating according to claim 1, wherein, The dispersant is selected from one of a polyurethane-based dispersant, a polyacrylate-based dispersant, or a copolymer with an anchoring group; The wetting agent is selected from one of a polyether-modified polysiloxane or an acetylene glycol surfactant; The defoaming agent is selected from one of a modified polysiloxane-based defoaming agent, a mineral oil-based defoaming agent, or a polyether-based defoaming agent; The thickening agent and the anti-settling agent are selected from one or a combination of several of fumed silica, organic bentonite, polyamide wax, or hydrogenated castor oil derivatives.

6. A method for preparing a high corrosion resistant nano-graphene coating, characterized in that, The method comprises the following steps: (1) Phase I: 10-30 parts by weight of epoxy resin, 0.1-1 parts by weight of dispersant, and 0.1-0.8 parts by weight of wetting agent are added to a kettle and mixed; heating is started, and the material temperature is controlled to 45-60°C; 2-10 parts by weight of graphene paste is added and subjected to high-speed shearing dispersion; the temperature is maintained, 20-70 parts by weight of zinc powder is added, and high-speed shearing dispersion is continued; (2) Phase II: heating is stopped, and the material is cooled to 25-30°C; low-speed stirring is switched, 5-40 parts by weight of phosphorus iron powder and 5-40 parts by weight of barium sulfate are added; low-speed stirring is maintained, 0.1-0.6 parts by weight of defoaming agent, 0.5-2 parts by weight of thickening agent, and 0.5-2 parts by weight of anti-settling agent are added, and mixed uniformly to obtain the A component; (3) The A component obtained in step (2) is mixed with the B component to prepare the high corrosion-resistant nanographene coating.

7. The method according to claim 6, wherein the method is characterized by, In step (1), the material temperature is controlled to 52.5-60°C, and the high-speed shearing dispersion speed is 2250-2500 rpm.

8. The method according to claim 6, wherein the method is characterized by, In step (1), the graphene paste is added and subjected to high-speed shearing dispersion for 20-30 minutes; after the zinc powder is added, high-speed shearing dispersion is continued for 30-40 minutes.

9. The method for preparing a highly corrosion-resistant nano-graphene coating according to claim 6, characterized in that, In step (2), the low-speed stirring speed is 800-1000 rpm.

10. The method for preparing a highly corrosion-resistant nano-graphene coating according to claim 6, characterized in that, In step (2), after adding the phosphorus iron powder and barium sulfate, low-speed stirring is carried out for 15-20 minutes; after adding the defoaming agent, thickening agent and anti-settling agent, low-speed stirring is continued for 15-20 minutes.

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