Corrosion-resistant layer of steel structure and manufacturing method of corrosion-resistant layer

Abstract

The invention discloses a corrosion-resistant layer of a steel structure and a manufacturing method of the corrosion-resistant layer, and belongs to the technical field of steel structure protection. The corrosion-resistant layer sequentially comprises a modified epoxy zinc-rich toughening primer layer, a functionalized epoxy micaceous iron oxide intermediate paint layer and a graphene-elastomer composite finish paint layer from inside to outside, and a synergistic design of toughening and impact resistance, strong bonding and falling prevention and efficient corrosion prevention is adopted. The manufacturing method comprises the steps of base material pretreatment, high-pressure airless spraying of all the coatings and a segmented curing process, and the combination and protection performance of the coatings is strengthened through component optimization and process cooperation. The problems that a traditional coating is fragile, easy to crack, easy to layer and fall off and unbalanced in performance are effectively solved, synergistic improvement of impact resistance, adhesive force and corrosion resistance is achieved, and the coating is suitable for steel structure protection in harsh environments such as railroad bridges and ocean platforms.

Description

Technical Field

[0001] This invention relates to the field of steel structure protection technology, specifically to a corrosion-resistant layer for steel structures and its manufacturing method. Background Technology

[0002] Steel structures are widely used in construction, transportation, and marine engineering due to their high strength and ease of construction. However, they are susceptible to corrosion failure in harsh environments such as humidity, salt spray, and acid / alkali media, leading to reduced structural strength, shortened service life, and even safety accidents. Existing anti-corrosion coatings for steel structures mostly employ a two-layer structure of "primer + topcoat" or a single anti-corrosion coating, which has the following technical defects: Insufficient impact resistance: Traditional coatings are brittle and easily crack and peel off when subjected to external impacts, making them unsuitable for scenarios such as vibration of railway bridges and impact of wind and waves on offshore platforms; Poor adhesion reliability: The bonding between the coating and the substrate, as well as between layers, largely relies on physical adsorption. With long-term use, delamination and peeling are likely to occur, leading to the failure of the anti-corrosion system.

[0003] Therefore, developing a corrosion-resistant layer that synergistically optimizes "toughening and impact resistance + strong adhesion and anti-detachment + high-efficiency corrosion protection" has become the key to solving the problem of protecting steel structures from harsh environments. Summary of the Invention

[0004] The purpose of this invention is to provide a corrosion-resistant layer for steel structures and its manufacturing method, so as to solve the problems of insufficient impact resistance and poor bonding reliability of existing materials.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A corrosion-resistant coating for steel structures comprises, from the inside out, a primer layer, an intermediate paint layer, and a topcoat layer. The primer layer contains a resin matrix, zinc powder, an elastomer component, and a self-healing component. The intermediate paint layer contains a resin matrix, flake-shaped anti-rust filler, modified carbon material, and a curing system. The topcoat layer contains a resin matrix, graphene, and an elastomer modification component. Through a synergistic design of "toughening and impact resistance + strong adhesion and anti-detachment + high-efficiency corrosion protection," it achieves a synergistic improvement in impact resistance, adhesion, and corrosion resistance, making it suitable for steel structure protection in harsh environments.

[0006] Further details: The primer layer has an epoxy resin matrix, an elastomer component consisting of core-shell structured acrylic-butadiene elastomer microspheres, and a self-healing functional component consisting of self-healing microcapsules. The primer layer also contains iron phosphate powder, a coupling agent, and fumed silica. The intermediate paint layer has a bisphenol A epoxy resin matrix, a mica iron oxide flake filler, and a 4-methyl-5-(1-naphthyl)-2-aminothiazole modified graphene oxide modified carbon material. The curing system includes a polyetheramine curing agent, and the intermediate paint layer also contains glass flakes and a urethane graft modifier. The topcoat layer has a high-hydroxyl acrylic polyurethane resin matrix, an elastomer modification component consisting of polysiloxane-modified acrylic elastomer, and the topcoat layer also contains titanium dioxide, an ultraviolet absorber, an antioxidant, and a substrate wetting agent.

[0007] Further details: In the primer layer, the epoxy resin has a mass fraction of 50%~60wt%, the zinc powder has a mass fraction of 70%~80wt% based on the primer solids, the elastomer component has a mass fraction of 3%~8wt%, and the self-healing functional component has a mass fraction of 5%~10wt%; In the intermediate paint layer, the bisphenol A epoxy resin has a mass fraction of 40%~50wt%, the mica iron oxide has a mass fraction of 30%~45wt%, the modified carbon material has a mass fraction of 2%~5wt%, and the polyetheramine curing agent to epoxy resin mass ratio is 1:3; In the topcoat layer, the high hydroxyl acrylic polyurethane resin has a mass fraction of 55%~65wt%, the graphene has a mass fraction of 1%~3wt%, and the elastomer modification component has a mass fraction of 8%~12wt%.

[0008] Further embodiment: The thickness of the primer layer is 120~160μm, the thickness of the intermediate paint layer is 250~300μm, and the thickness of the topcoat layer is 70~80μm.

[0009] Further solution: The self-healing microcapsules can release functionalized graphene acrylic slurry at pH≤6, and the modified carbon material, after being modified by a urethane graft modifier, strengthens its bonding with the intermediate paint layer resin matrix.

[0010] Further details: The corrosion-resistant layer shall meet the following requirements: impact resistance (no cracking or peeling after 50 cm·kg impact as specified in GB / T1732-1993 standard); adhesion (≥18 MPa pull-off adhesion as specified in GB / T5210-2006 standard); salt spray resistance (no blistering, red rust, or peeling after 5000 hours as specified in GB / T1771-2007 standard); and weather resistance (no powdering or cracking after 3000 hours of accelerated aging as specified in GB / T1865-2009 standard).

[0011] A method for manufacturing a corrosion-resistant coating for a steel structure includes the following steps: Step 1: Substrate pretreatment, which involves sandblasting, chemical cleaning, and silane coupling agent treatment to form a substrate-coating bonding base; Step 2: Coating preparation and application. High-pressure airless spraying is used to prepare and apply the primer layer, intermediate paint layer and topcoat layer in sequence. Step 3: Segmented curing. Each coating layer is cured at a gradient temperature and placed at room temperature to reduce internal stress.

[0012] Further steps: In step one: the sandblasting treatment is carried out to Sa3.0 grade, and the surface roughness Ra is controlled to be 60~100μm; the chemical cleaning is carried out in sequence as alkali washing, water washing, acid washing, water washing, and drying. The alkali washing uses 5% sodium hydroxide solution and is treated at 20~30℃ for 10~15min. The acid washing uses 1% hydrochloric acid solution and is treated at 20~30℃ for 5~8min. The drying temperature is 80~100℃ and the time is 30~40min. The silane coupling agent is γ-aminopropyltriethoxysilane (KH550), which is sprayed with a 1%~2% ethanol solution within 1 hour after sandblasting and drying, and then air-dried at room temperature for 5~10min.

[0013] Further solution: In step two: the preparation of the primer layer includes: mixing epoxy resin and resin diluent at a mass ratio of 10:1, adding dispersant, wetting agent, defoamer, and thickener and continuing to stir to obtain a resin mixture; after adjusting the speed, adding zinc powder, phosphorus iron powder, anti-settling agent, glass microspheres and coupling agent in sequence and stirring to obtain a film-forming component; mixing curing agent and curing diluent at a mass ratio of 8:1, adding flash rust inhibitor and stirring to obtain a curing component; mixing the film-forming component, curing component, and self-healing microcapsules at a mass ratio of 100:30:8, adding fumed silica and defoamer and stirring to obtain a primer; applying in 2-3 coats, each with a dry film thickness of 40-60 μm, with an interval of 2-4 hours between coats; Further formulation: The preparation of the intermediate coating layer includes: stirring modified graphene oxide with urethane graft modifier at room temperature for 3-5 hours to obtain functionalized modified graphene oxide; mixing and stirring bisphenol A epoxy resin and dispersant, adding functionalized modified graphene oxide and continuing stirring, reducing the speed and then sequentially adding cosolvent, glass flakes, and mica iron oxide, followed by adding curing agent and stirring to obtain the intermediate coating; applying the coating in a single spray, with a wet film thickness of 300-380 μm, and applying the topcoat layer within 30 minutes after surface drying; the preparation of the topcoat layer includes: dispersing graphene in ethanol using ultrasonic dispersion, adding triethylamine and storing in an ice bath to obtain a graphene dispersion; mixing and stirring high-hydroxyl acrylic polyurethane resin and polysiloxane-modified acrylic elastomer, adding hydroxyl acrylic dispersion and continuing stirring; mixing and grinding deionized water, dispersant, and titanium dioxide, then adding to the above resin system, followed by adding graphene dispersion, weather-resistant additives, and substrate wetting agent and stirring to obtain the topcoat; the wet film thickness during coating is 80-90 μm.

[0014] Further solution: In step three: the segmented curing is specifically as follows: after the primer layer is applied, pre-curing at 60℃ for 30 min → placing at room temperature for 1 h; after the intermediate paint layer is applied, curing at 80℃ for 1 h → placing at room temperature for 1 h; after the topcoat layer is applied, curing at 100℃ for 2 h → placing at room temperature for 24 h; during the preparation of each coating, the stirring speed of the raw materials is 300~1800 rpm, the stirring time is 10~150 min, and the interval between the addition of adjacent solid raw materials is not less than 20 min.

[0015] The present invention has the following beneficial effects: This invention effectively solves the problem of brittleness and easy cracking of traditional coatings by using a three-layer synergistic design of "primer layer + intermediate layer + topcoat layer" and the core logic of "toughening and impact resistance + strong adhesion and anti-detachment + high-efficiency anti-corrosion". It also utilizes the synergistic effect of elastomer components penetrating each layer to absorb impact energy and inhibit crack propagation. The dual design of substrate pretreatment, physical integration of sheet fillers and interlayer chemical bonding enhances the reliability of the coating's bonding with the substrate and between layers, preventing delamination and peeling during long-term use. While retaining the advantages of self-healing and graphene modification for high-efficiency corrosion protection, the optimization of various coating components and process synergy have achieved simultaneous improvement in corrosion resistance, impact resistance, adhesion and other comprehensive mechanical properties, which significantly broadens the application range of steel structures in harsh environments and provides long-term and stable protection for steel structures. Attached Figure Description

[0016] Figure 1 The diagram shows the detailed steps of the preparation method in this invention. Detailed Implementation

[0017] The present invention will be described in detail below with reference to specific embodiments, aiming to clarify the technical solution, implementation process and technical effects of the present invention, and not to limit the scope of protection of the present invention. The raw materials used in this embodiment are all commercially available conventional products, and the testing equipment all meet the requirements of the corresponding national standards; the term "harsh environment" refers to environments with salt spray, acid and alkali media, mechanical impact, or frequent temperature changes (such as offshore platforms, railway bridges, etc.); "elastomer component" refers to a polymeric elastic material with impact energy absorption capacity; "modified carbon material" refers to a carbon-based material that has been chemically modified to have the function of blocking corrosive media.

[0018] (a) Exemplary Example 1: Basic Framework of Product Structure This exemplary embodiment discloses the typical structure and key parameters of the above-mentioned corrosion-resistant layer, as follows: Primer layer: The resin matrix is ​​epoxy resin (55wt%), zinc powder is 75wt% by solids, the elastomer component is core-shell structured acrylic-butadiene elastomer microspheres (5wt%), the self-healing functional component is self-healing microcapsules (8wt%), supplemented with iron phosphate powder (6wt%), titanate coupling agent (0.8wt%), and fumed silica (1.5wt%); the thickness is 140μm, and the self-healing microcapsules release functionalized graphene acrylic slurry when pH≤6.

[0019] Intermediate coating layer: The resin matrix is ​​bisphenol A epoxy resin (45wt%), the flake-shaped anti-rust filler is mica iron oxide (38wt%), the modified carbon material is 4-methyl-5-(1-naphthyl)-2-aminothiazole modified graphene oxide (3wt%), the curing system includes polyetheramine curing agent (1:3 mass ratio with epoxy resin), supplemented with glass flakes (8wt%) and urethane graft modifier (2wt%); thickness 280μm.

[0020] Topcoat layer: The resin matrix is ​​high hydroxyl acrylic polyurethane resin (60wt%), graphene (2wt%), the elastomer modification component is polysiloxane modified acrylic elastomer (10wt%), supplemented with titanium dioxide (12wt%), ultraviolet absorber (0.8wt%), antioxidant (0.8wt%), and substrate wetting agent (0.5wt%); thickness 75μm.

[0021] (ii) Exemplary Example 2: Basic Framework of Preparation Method This exemplary embodiment discloses a typical manufacturing method and quantitative parameters for the aforementioned corrosion-resistant layer, as detailed below: Substrate pretreatment: Sandblasting to Sa3.0 grade, surface roughness Ra=80μm; Alkali washing (5% sodium hydroxide solution, 25℃, 12min) → water washing → acid washing (1% hydrochloric acid solution, 25℃, 6min) → water washing → drying (90℃, 35min); Within 40min after sandblasting and drying, spray with 1.5wt% γ-aminopropyltriethoxysilane (KH550) ethanol solution and air dry at room temperature for 8min.

[0022] Coating preparation and application: Primer preparation: Epoxy resin and resin diluent are mixed at a ratio of 10:1 and stirred at 880 rpm for 30 min. Dispersant and wetting agent are added and stirred for 18 min. The speed is adjusted to 1600 rpm, and zinc powder, ferrophosphorus powder, etc. are added sequentially (with an interval of 20 min between adjacent raw materials). Stirring is carried out for 130 min to obtain the film-forming component. Curing agent and curing diluent are mixed at a ratio of 8:1, and flash rust inhibitor is added and stirred at 550 rpm for 12 min to obtain the curing component. Film-forming component: Curing component: Self-healing microcapsules = 100:30:8 are mixed and stirred at 350 rpm for 20 min. Fumed silica is added and stirred at 650 rpm for 20 min. Three coats are applied under high pressure without air, each with a dry film thickness of 50 μm, with an interval of 3 h.

[0023] Intermediate coating preparation: Modified graphene oxide and urethane graft modifier were stirred at room temperature for 4 hours; bisphenol A epoxy resin and dispersant were stirred at 880 rpm for 12 minutes, and modified graphene oxide was added and stirred for 65 minutes; the speed was reduced to 580 rpm, co-solvent, glass flakes, and mica iron oxide were added and stirred for 65 minutes, and the curing agent compound system was added and stirred at 880 rpm for 75 minutes; one coat was sprayed with high pressure airless spray, with a wet film thickness of 350 μm, and the topcoat was applied 20 minutes after surface drying.

[0024] Topcoat preparation: Graphene was dispersed in ethanol and ultrasonically dispersed at 100 kHz for 50 min, then stored in an ice bath (2 °C) with triethylamine; high hydroxyl acrylic polyurethane resin and elastomer were stirred at 650 rpm for 25 min, and hydroxyl acrylic dispersion was added and stirred for 18 min; deionized water, dispersant, and titanium dioxide were ground to a fineness ≤20 μm, added to the resin system and stirred for 35 min, then graphene dispersion (mass ratio of 1:8 to the resin system) and additives were added and stirred at 600 rpm for 25 min; one coat was applied with high pressure airless spraying, resulting in a wet film thickness of 85 μm.

[0025] Segmented curing: After applying the primer, pre-cure at 60℃ for 30 minutes → place at room temperature for 1 hour; after applying the intermediate coat, cure at 80℃ for 1 hour → place at room temperature for 1 hour; after applying the topcoat, cure at 100℃ for 2 hours → place at room temperature for 24 hours.

[0026] (III) Specific Example 1: Preparation and Performance Verification of a Single Primer Layer Implementation steps: The Q235 steel structure substrate is treated according to the substrate pretreatment process of Exemplary Example 2; only the modified epoxy zinc-rich toughened primer layer (with parameters the same as the primer layer in Exemplary Example 1) is prepared and coated, and cured according to the corresponding curing process to obtain a single primer layer sample.

[0027] Key parameters: primer thickness 140μm, other preparation parameters are the same as in Exemplary Example 2.

[0028] (iv) Specific Example 2: Preparation and Performance Verification of Primer + Intermediate Coating Implementation steps: The Q235 steel structure substrate is treated according to the substrate pretreatment process of Exemplary Example 2; a primer layer and an intermediate paint layer are prepared and coated in sequence (the parameters are the same as those of the primer layer and intermediate paint layer in Exemplary Example 1), and the substrate is treated according to the corresponding coating interval and curing process to obtain a double-layer coating sample.

[0029] Key parameters: primer thickness 140μm, intermediate coat thickness 280μm, other preparation parameters are consistent with exemplary embodiment 2.

[0030] (V) Specific Example 3: Preparation and Performance Verification of Complete Three-Layer Coating Implementation steps: Process the Q235 steel structure substrate according to the process of Exemplary Example 2; prepare and coat the primer layer, intermediate paint layer and topcoat layer in sequence (parameters are the same as Exemplary Example 1), and process according to the corresponding coating interval and curing process to obtain a complete three-layer coating sample.

[0031] Key parameters: primer 140μm, intermediate coat 280μm, topcoat 75μm; other preparation parameters are consistent with Exemplary Example 2.

[0032] (vi) Comparative Example: Preparation and Performance Verification of Coatings Without Elastomer Components Implementation steps: Same as in specific embodiment 3, except that the elastomer components (core-shell structured acrylic-butadiene elastomer microspheres in the primer, polyetheramine curing agent in the intermediate coat, and polysiloxane modified acrylic elastomer in the topcoat) in the three-layer coating were removed. The remaining raw material ratios, preparation processes and parameters were the same as in specific embodiment 3, and a comparative coating sample was obtained.

[0033] (vii) Test Example: Performance Testing Testing standards and equipment: Impact resistance: GB / T1732-1993, QCJ type impact testing machine, room temperature conditions; Adhesion (coating-substrate): GB / T5210-2006, DL-5000 type pull-off adhesion tester, loading rate 5mm / min; Interlayer bonding strength: GB / T9286-1998, cross-cut test (grid size 1mm×1mm), tape peel test; Salt spray resistance: GB / T1771-2007, YWX / Q-750 salt spray test chamber, 5% NaCl solution, neutral salt spray; Weather resistance: GB / T1865-2009, QUV / Spray type artificial accelerated aging test chamber, ultraviolet light irradiation + condensation cycle; Acid and alkali resistance: GB / T9274-1988, constant temperature water bath, pH=4 hydrochloric acid / pH=10 sodium hydroxide solution, immersion at room temperature.

[0034] Test results:

[0035] (viii) Results Analysis Comparison of single coating and composite coating: Specific Example 1 (single primer layer) has basic rust prevention and acid and alkali resistance, but its impact resistance (35cm·kg) and adhesion (15.2MPa) are insufficient, and its salt spray resistance and weather resistance are limited, proving that a single coating cannot meet the requirements of harsh environments; Specific Example 2 (double coating) significantly improves impact resistance, adhesion, and salt spray resistance through the barrier effect of the intermediate paint and the interlayer bonding design, but it lacks the weather resistance and wear resistance protection of the topcoat, and the interlayer bonding strength is only level 1, leaving room for optimization; Specific Example 3 (complete three-layer coating) achieves optimal performance in all aspects through the synergistic effect of "primer rust prevention and repair + intermediate paint barrier and connection + topcoat wear resistance and weather resistance", verifying the necessity of the three-layer structure design.

[0036] Core innovation verification: Compared with Example 3, which removed the elastomer component, the impact resistance was only 28 cm·kg (a decrease of 44% compared with Example 3), the interlayer bonding strength dropped to level 2, and the salt spray resistance and weather resistance were significantly reduced. This proves that "the toughening and impact resistance synergistic effect of elastomer penetrating three layers" is the core innovation to improve the overall performance of the coating. The adhesion (19.8 MPa) and salt spray resistance (no abnormalities after 5000h) of Example 3 are better than the existing technology, which reflects the technical advantages of "strong adhesion and anti-detachment design" and "combination of corrosion protection and performance".

[0037] Application feasibility verification: The performance of Specific Embodiment 3 meets the expected indicators in the claims, and the testing process strictly follows national standards. The data is repeatable and verifiable, proving that the corrosion-resistant layer and manufacturing method of the present invention have the conditions for industrial implementation and can be stably applied to harsh environments such as railway bridges and offshore platforms.

[0038] The above description is only a preferred 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 corrosion-resistant layer for a steel structure, characterized in that, From the inside out, it includes a primer layer, an intermediate paint layer, and a topcoat layer; The primer layer comprises a resin matrix, zinc powder, elastomer components, and self-healing functional components; The intermediate paint layer comprises a resin matrix, flake-shaped anti-rust filler, modified carbon material, and a curing system; The topcoat layer comprises a resin matrix, graphene, and elastomer-modified components.

2. The corrosion-resistant layer of the steel structure according to claim 1, characterized in that, The resin matrix of the primer layer is epoxy resin, the elastomer component is core-shell structured acrylic-butadiene elastomer microspheres, the self-healing functional component is self-healing microcapsules, and the primer layer also contains iron phosphate powder, coupling agent and fumed silica. The resin matrix of the intermediate paint layer is bisphenol A epoxy resin, the sheet-like anti-rust filler is mica iron oxide, the modified carbon material is 4-methyl-5-(1-naphthyl)-2-aminothiazole modified graphene oxide, the curing system includes polyetheramine curing agent, and the intermediate paint layer also includes glass flakes and urethane graft modifier. The resin matrix of the topcoat layer is a high-hydroxyl acrylic polyurethane resin, the elastomer modification component is a polysiloxane-modified acrylic elastomer, and the topcoat layer also contains titanium dioxide, ultraviolet absorber, antioxidant and substrate wetting agent.

3. The corrosion-resistant layer of the steel structure according to claim 2, characterized in that, In the primer layer, the epoxy resin has a mass fraction of 50%~60wt%, the zinc powder has a mass fraction of 70%~80wt% based on the primer solids, the elastomer component has a mass fraction of 3%~8wt%, and the self-healing functional component has a mass fraction of 5%~10wt%. In the intermediate paint layer, the bisphenol A epoxy resin has a mass fraction of 40%~50wt%, the mica iron oxide has a mass fraction of 30%~45wt%, the modified carbon material has a mass fraction of 2%~5wt%, and the polyetheramine curing agent to epoxy resin mass ratio is 1:

3. In the topcoat layer, the high hydroxyl acrylic polyurethane resin has a mass fraction of 55%~65wt%, the graphene has a mass fraction of 1%~3wt%, and the elastomer modification component has a mass fraction of 8%~12wt%.

4. A method for manufacturing a corrosion-resistant layer for a steel structure as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Substrate pretreatment, which involves sandblasting, chemical cleaning, and silane coupling agent treatment to form a substrate-coating bonding base; Step 2: Coating preparation and application. High-pressure airless spraying is used to prepare and apply the primer layer, intermediate paint layer and topcoat layer in sequence. Step 3: Segmented curing. Each coating layer is cured at a gradient temperature and placed at room temperature to reduce internal stress.

5. The manufacturing method according to claim 4, characterized in that, In step one: the sandblasting treatment is carried out to Sa3.0 grade, and the surface roughness Ra is controlled to be 60~100μm; the chemical cleaning is carried out in sequence as alkali washing, water washing, acid washing, water washing, and drying. The alkali washing uses 5% sodium hydroxide solution and is treated at 20~30℃ for 10~15min. The acid washing uses 1% hydrochloric acid solution and is treated at 20~30℃ for 5~8min. The drying temperature is 80~100℃ and the time is 30~40min; the silane coupling agent is γ-aminopropyltriethoxysilane, which is sprayed with a 1%~2% ethanol solution within 1 hour after sandblasting and drying, and then air-dried at room temperature for 5~10min.

6. The manufacturing method according to claim 4, characterized in that, In step two: the preparation of the primer layer includes: mixing epoxy resin and resin diluent at a mass ratio of 10:1, adding dispersant, wetting agent, defoamer, and thickener and continuing to stir to obtain a resin mixture; After adjusting the rotation speed, zinc powder, ferric phosphorus powder, anti-settling agent, glass microspheres and coupling agent are added in sequence, and the mixture is stirred to obtain the film-forming component; The curing agent and curing diluent were mixed at a mass ratio of 8:1, and the flash rust inhibitor was added and stirred to obtain the curing component. The film-forming component, curing component, and self-healing microcapsule were mixed in a mass ratio of 100:30:8, and fumed silica and defoamer were added and stirred to prepare the primer. The coating is applied in 2 to 3 coats, with each coat having a dry film thickness of 40 to 60 μm and an interval of 2 to 4 hours between coats.

7. The manufacturing method according to claim 6, characterized in that, The preparation of the intermediate coating layer includes: stirring modified graphene oxide with a urethane graft modifier at room temperature for 3-5 hours to obtain functionalized modified graphene oxide. Bisphenol A epoxy resin and dispersant were mixed and stirred, functionalized modified graphene oxide was added and stirred again, the speed was reduced and then the co-solvent, glass flakes and mica iron oxide were added in sequence, and then the curing agent was added and stirred to prepare the intermediate paint. The coating is applied in a single spray application, with a wet film thickness of 300~380μm. The topcoat layer is applied within 30 minutes after surface drying. The preparation of the topcoat layer includes: Graphene was dispersed in ethanol by ultrasonic dispersion, and triethylamine was added and stored in an ice bath to obtain a graphene dispersion; high hydroxyl acrylic polyurethane resin and polysiloxane modified acrylic elastomer were mixed and stirred, and hydroxyl acrylic dispersion was added and stirring continued. Deionized water, dispersant, and titanium dioxide are mixed and ground, then added to the above resin system. Graphene dispersion, weather-resistant additives, and substrate wetting agents are then added and stirred to prepare the topcoat. The wet film thickness during coating is 80~90μm.

8. The manufacturing method according to claim 4, characterized in that, In step three: the segmented curing is specifically as follows: after the primer layer is applied, it is pre-cured at 60°C for 30 minutes and then placed at room temperature for 1 hour; after the intermediate paint layer is applied, it is cured at 80°C for 1 hour and then placed at room temperature for 1 hour; after the topcoat layer is applied, it is cured at 100°C for 2 hours and then placed at room temperature for 24 hours; during the preparation of each coating, the stirring speed of the raw materials is 300~1800 rpm, the stirring time is 10~150 minutes, and the interval between the addition of adjacent solid raw materials is not less than 20 minutes.

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