Graphene reinforced heavy duty epoxy coating for marine environment

Abstract

This invention relates to the field of functional coatings technology, specifically a graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments. It comprises the following raw materials in parts by weight: 60-80 parts bisphenol A type epoxy resin, 5-10 parts amino-graphene-carbon nanotube composite powder, 3-6 parts zinc-aluminum-cerium ternary composite phosphate, 3-6 parts nano-boron nitride / silica core-shell particles, 15-25 parts polyamide-epoxy curing agent, 1-3 parts silane coupling agent KH-560, 5-8 parts cashew nutshell oil-modified phenolic amine, 0.5-2 parts carboxylated graphene quantum dots, 2-4 parts organomontmorillonite, 0.1-0.5 parts fluorocarbon surfactant, 8-15 parts composite anti-rust pigment, and 10-20 parts organic solvent. This coating exhibits excellent anti-corrosion performance, providing long-term resistance to marine corrosion, high temperature resistance, and cathodic disbondment resistance. It also possesses aging tracing and anti-bioadhesion functions, is easy to apply, and has stable performance, providing reliable protection for marine engineering projects.

Description

Technical Field

[0001] This invention relates to the field of functional coatings technology, specifically a graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments. Background Technology

[0002] The marine environment, with its high salinity, high humidity, strong corrosive ions, and marine organism adhesion, exerts a strong corrosive effect on metal components, resulting in significant economic losses and safety hazards annually. Currently, epoxy coatings are the primary type of coating used for marine corrosion protection, but they have significant shortcomings in long-term corrosion resistance, high-temperature resistance, and resistance to biofouling, making it difficult to meet the long-term protection requirements of the extreme marine environment.

[0003] Traditional epoxy coatings often rely on single anti-rust pigments, functioning only through physical barrier and simple chemical passivation. Prolonged immersion in seawater can lead to pigment loss and coating blistering, typically resulting in salt spray resistance of less than 3000 hours and seawater immersion resistance of less than 200 days. To improve corrosion resistance, some processes introduce graphene as a reinforcing filler; however, without surface modification, graphene exhibits poor compatibility with epoxy resin, easily agglomerating and forming defects. This not only fails to provide a barrier effect but also reduces coating density and accelerates the penetration of corrosive media.

[0004] Meanwhile, existing coatings lack multifunctional designs for marine environments: their high-temperature resistance is insufficient, and the coating is prone to softening and cracking in the high temperatures of the ocean surface in summer or in the local high temperatures of deep-sea operating equipment; their resistance to cathodic disbondment is weak, and the cathodic protection technology commonly used in marine engineering can easily cause the coating to peel off from the metal substrate, losing its protective effect; moreover, most coatings do not have aging tracing functions, making it difficult to monitor coating failure in real time, requiring periodic shutdowns for testing, which increases maintenance costs and safety risks.

[0005] In addition, the curing agents of traditional coatings are mostly pure polyamides, which have a short pot life and low curing efficiency. The adhesion of the coating after construction is easily affected by humidity. Some fillers have poor dispersibility and cannot be evenly distributed in the coating, resulting in large fluctuations in anti-corrosion performance.

[0006] In summary, current marine epoxy coatings suffer from problems such as short anti-corrosion cycle, limited functionality, high construction and maintenance costs, and insufficient performance stability. There is an urgent need to develop a graphene-reinforced heavy-duty anti-corrosion epoxy coating that combines long-lasting anti-corrosion, high temperature resistance, cathodic disbondment resistance, traceable aging, and excellent workability to meet the long-term and stable protection needs of marine engineering. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the shortcomings of existing technologies, this invention provides a graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments.

[0009] (II) Technical Solution

[0010] A graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments is composed of the following raw materials in parts by weight: 60-80 parts of bisphenol A type epoxy resin, 5-10 parts of amino-graphene-carbon nanotube composite powder, 3-6 parts of zinc-aluminum-cerium ternary composite phosphate, 3-6 parts of nano boron nitride / silica core-shell particles, 15-25 parts of polyamide-epoxy curing agent, 1-3 parts of silane coupling agent KH-560, 5-8 parts of cashew nut shell oil modified phenolic amine, 0.5-2 parts of carboxylated graphene quantum dots, 2-4 parts of organomontmorillonite, 0.1-0.5 parts of fluorocarbon surfactant, 8-15 parts of composite anti-rust pigment, and 10-20 parts of organic solvent.

[0011] Preferably, the preparation process of the amino-based graphene-carbon nanotube composite powder is also included; graphene and carbon nanotubes are weighed at a mass ratio of 5:1, deionized water is added, and then 1-2% of nitric acid is added to the total mass. The mixture is ultrasonically dispersed for 30-60 minutes with the ultrasonic power controlled at 400-600W. 5-8% of 3-aminopropyltriethoxysilane is added to the total mass. The temperature is raised to 60-70℃, and the mixture is stirred for 4-6 hours. After the reaction is completed, the mixture is filtered. The resulting solid is calcined at 600-800℃ for 2-3 hours under nitrogen protection. After cooling, the solid is ground and passed through a 200-mesh sieve. The obtained composite powder has an amino content of 2.0-3.5 mmol / g and a specific surface area of ​​150-200 m² / g.

[0012] Preferably, the preparation process of the nano-boron nitride / silica core-shell particles is also included: nano-boron nitride is added to ethanol and ultrasonically dispersed; 10-15% tetraethyl orthosilicate is added dropwise to the dispersion; 0.5-1% ammonia is added to adjust the pH to 8.0-9.0; the temperature is raised to 50-60℃ and stirred for reaction; after the reaction is completed, the particles are separated by centrifugation; the obtained solid is dried at 60-80℃ for 4-6 hours; the obtained core-shell particles have a particle size of 80-120nm, a silica shell thickness of 10-20nm, and a thermal conductivity of ≤0.15W / (m·K) at 200-250℃.

[0013] Preferably, the preparation process also includes a zinc-aluminum-cerium ternary composite phosphate; zinc nitrate, aluminum nitrate, and cerium nitrate are weighed in a mass ratio of 2:1:1, dissolved in deionized water to prepare a 0.5-1 mol / L mixed solution, 1-2 mol / L phosphoric acid solution is added dropwise to the mixed solution, the pH is adjusted to 3.0-4.0, the temperature is raised to 50-60℃ and stirred to react, after the reaction is completed, the solid is filtered to obtain a solid, washed with deionized water until neutral, dried at 80-100℃, ground and passed through a 300-mesh sieve; the obtained product has a particle size of 50-80 nm and a purity of not less than 98%; and is compatible with Cl... － The reaction rate is ≥0.8 mmol / (g·h).

[0014] Preferably, the preparation process of carboxyl-based graphene quantum dots is also included; graphene quantum dots are weighed, deionized water is added, and then maleic anhydride accounting for 5-10% of the total mass is added, and ultrasonic dispersion is performed. The temperature is raised to 70-80℃ and stirred for reaction. After the reaction is completed, dialysis treatment is performed. The molecular weight cutoff of the dialysis bag is 3000 Da, the dialysis time is 24-36 hours, and then freeze-drying is performed. The obtained product has a carboxyl content of 1.5-2.5 mmol / g, a fluorescence quantum yield ≥30%, and a fluorescence intensity decay rate ≤10% / 1000h at 200-250℃.

[0015] Preferably, the process also includes the preparation of organomontmorillonite; this process uses hexadecyltrimethylammonium bromide for modification, montmorillonite is added to deionized water and ultrasonically dispersed for 20-30 minutes, then 8-12% of hexadecyltrimethylammonium bromide is added, the temperature is raised to 70-80℃, and the mixture is stirred for 4-6 hours. After the reaction is completed, the mixture is centrifuged, washed with deionized water until no bromide ions are detected, and dried at 60-80℃ for 8-10 hours. The interlayer spacing is 2.0-2.5 nm, the viscosity increase rate of the mixture with bisphenol A epoxy resin is ≤15%, and the water permeability is ≤0.9 g / m²·24h.

[0016] Preferably, the preparation process of the polyamide-epoxy curing agent is also included; polyamide 650 and epoxy resin E-51 are weighed at a mass ratio of 3:1, mixed, heated to 70-80℃, stirred and reacted for 1-2 hours, cooled to 40-50℃, and 0.5-1% of dibutyltin dilaurate is added, and stirring is continued for 30-45 minutes; the amine value of the obtained curing agent is 200-250mgKOH / g, and the pot life is 8-12 hours.

[0017] Preferably, the preparation method of the graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments includes the following steps:

[0018] S1: Add bisphenol A type epoxy resin and organic solvent to the dispersion vessel and stir at a speed of 800-1000 r / min for 10-15 minutes;

[0019] S2: Add amino-graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano boron nitride / silica core-shell particles, and organomontmorillonite. Heat to 50-60℃ and disperse at 1500-2000r / min for 30-45 minutes. Simultaneously, perform ultrasonic-assisted treatment for 10-15 minutes with an ultrasonic power of 300-500W.

[0020] S3: Add silane coupling agent KH-560 and continue stirring for 15-20 minutes;

[0021] S4: Cool down to 30-40℃, add composite rust-preventive pigments and fluorocarbon surfactants, and disperse at a speed of 1200-1500r / min for 20-30 minutes;

[0022] S5: Add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots, stir at 800-1000 r / min for 15-20 minutes, and then filter through a 100-150 mesh filter to obtain the finished coating; the fineness of the finished product is no greater than 50 μm, and the viscosity at 25℃ is 800-1200 mPa·s.

[0023] Preferably, the dispersion process in step S2 uses dual-frequency ultrasonic treatment, that is, 20kHz and 40kHz frequencies are used alternately, and the frequency is switched every 10 minutes; after dispersion is completed, samples are taken for testing, and the particle size of the filler agglomerates is no greater than 100nm, and the dispersion uniformity deviation is no greater than 5%.

[0024] Preferably, the composite anti-rust pigment is composed of zinc phosphate, aluminum tripolyphosphate, and zinc molybdate in a mass ratio of 3:2:1; the organic solvent is a mixture of xylene and n-butanol in a volume ratio of 4:1; the zinc-aluminum-cerium ternary composite phosphate reacts with corrosion ions to generate ZnCl2, AlCl3, CeCl3, and PO4. 3- The bisphenol A type epoxy resin has an epoxy value of 0.51 eq / 100g.

[0025] (iii) Beneficial technical effects

[0026] Compared with existing technologies, the beneficial effects of this invention are:

[0027] 1. Using aminated graphene-carbon nanotube composite powder as the core reinforcing phase, the interfacial bonding force with epoxy resin is significantly improved through the reaction of surface amino groups with silane coupling agents, solving the problem of easy agglomeration of traditional graphene and forming a dense barrier network to effectively delay the penetration of corrosive media. Zinc-aluminum-cerium ternary composite phosphate and nano boron nitride / silica core-shell particles work synergistically. The former reacts with corrosive ions to generate a stable passivation film, while the latter improves the coating's high-temperature resistance and insulation, making up for the shortcomings of traditional coatings in terms of single corrosion protection and poor high-temperature resistance. The modified organomontmorillonite has improved compatibility with the resin, further optimizing the coating's density, while fluorocarbon surfactants endow the coating with a certain degree of anti-bioadhesion ability, reducing the damage of marine organisms to the coating.

[0028] 2. The introduction of carboxyl-based graphene quantum dots enables coating aging tracking, allowing monitoring of coating failure without downtime and reducing maintenance costs. These quantum dots are prepared through maleic anhydride modification, dialysis bag purification, and freeze-drying, achieving a carboxyl content of 1.5-2.5 mmol / g and a fluorescence quantum yield of 35%. This ensures compatibility with epoxy resins and polyamide-epoxy curing agents for uniform dispersion within the coating, while also exhibiting stable fluorescence emission characteristics. In marine environments, when the coating undergoes polarity changes due to chemical corrosion, the fluorescence intensity of the quantum dots decreases linearly with ion penetration. Physical damage results in a blue shift in fluorescence wavelength or local signal loss. Since the fluorescence decay rate during UV / humid heat aging is negatively correlated with the degree of aging, these fluorescence signal changes can be detected in situ using a portable fluorescence spectrometer or imager.

[0029] 3. The curing system uses a polyamide-epoxy pre-reaction curing agent combined with cashew nut shell oil-modified phenolic amine, which extends the pot life and improves curing efficiency, ensuring that the coating still has strong adhesion in a high-humidity marine environment, thus solving the problem of limited application of traditional curing agents.

[0030] 4. Furthermore, the preparation method claimed in this application allows the aforementioned components to exhibit superior synergistic effects, resulting in a coating with significantly better performance than similar products: adhesion reaches 6.0 MPa, salt spray resistance reaches 6000 hours, seawater immersion resistance reaches 420 days, high-temperature weight loss rate is 0.6-0.8% / 1000h, and cathodic disbondment resistance reaches 1500 hours, making it suitable for long-term protection in marine high-salt, high-temperature, and cathodic protection environments; in terms of mechanical and anti-permeability properties, tensile strength reaches 38.2 MPa, elongation at break is 4.8-5.5%, water permeability is 0.68-0.85 g / m²·24h, and chloride ion permeability is 0.25-0.32 mg / m²·d, effectively blocking the penetration of corrosive media and solving the problem of traditional coatings being easily corroded by ions. Attached Figure Description

[0031] Figure 1 This is a flowchart of a graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments, as disclosed in this invention.

[0032] Figure 2 This is a bar graph comparing the adhesion and salt spray resistance of the examples and comparative examples;

[0033] Figure 3 This is a line graph comparing water permeability and chloride ion permeability in the examples and comparative examples;

[0034] Figure 4 This is a bar chart comparing the UV aging resistance and damp heat aging resistance of the examples and comparative examples. Detailed Implementation

[0035] according to Figures 1 to 4The specific embodiments of the present invention are as follows:

[0036] Raw material preparation

[0037] The raw materials used in this embodiment are as follows: bisphenol A type epoxy resin with an epoxy value of 0.51 eq / 100g, graphene sheets with a diameter of 1-5 μm and a thickness of 0.5-2 nm, carbon nanotubes with a diameter of 20-50 nm and a length of 1-5 μm, zinc nitrate with a purity of 99%, aluminum nitrate with a purity of 99%, cerium nitrate with a purity of 99%, phosphoric acid concentration of 85%, nano boron nitride with a particle size of 50-100 nm, tetraethyl orthosilicate with a purity of 98%, ammonia concentration of 25%, polyamide 650 with an amine value of 300-350 mg KOH / g, epoxy resin E-51 with an epoxy value of 0.51 eq / 100g, dibutyltin dilaurate with a purity of 96%, silane coupling agent KH-560 with a purity of 98%, cashew nut shell oil modified phenolic amine with an amine value of 280-320 mg KOH / g, graphene quantum dots with a particle size of 3-5 nm, maleic anhydride with a purity of 99%, and montmorillonite with a cation exchange capacity of 3-5 nm. 100 meq / 100g, cetyltrimethylammonium bromide purity 99%, fluorocarbon surfactant surface tension 20 mN / m, zinc phosphate purity 98%, aluminum tripolyphosphate purity 98%, zinc molybdate purity 99%, xylene purity 99%, n-butanol purity 99%.

[0038] intermediate preparation

[0039] Preparation of amino-based graphene-carbon nanotube composite powder: 50g graphene and 10g carbon nanotubes were weighed and added to 1000mL deionized water with 1.2g nitric acid. The mixture was ultrasonically dispersed at 400W for 45 minutes. 6g 3-aminopropyltriethoxysilane was added and stirred at 65℃ for 5 hours. After filtration, the mixture was calcined at 700℃ for 2.5 hours under nitrogen protection, cooled, ground, and passed through a 200-mesh sieve. The amino content was measured to be 2.8mmol / g and the specific surface area was 180m² / g.

[0040] Preparation of boron nitride / silica core-shell nanoparticles: 50g of boron nitride nanoparticles were added to 500mL of ethanol and ultrasonically dispersed at 300W for 25 minutes; 8g of tetraethyl orthosilicate and 0.5g of ammonia were added dropwise to adjust the pH to 8.5; the mixture was stirred at 55℃ for 4 hours; after centrifugation, the particles were dried at 70℃ for 5 hours and the silica shell thickness was measured to be 15nm.

[0041] Preparation of zinc-aluminum-cerium ternary composite phosphate: Weigh 20g zinc nitrate, 10g aluminum nitrate, and 10g cerium nitrate and dissolve them in 500mL deionized water to prepare a 0.8mol / L solution; add 1.5mol / L phosphoric acid solution to adjust the pH to 3.5; stir the reaction at 55℃ for 2.5 hours; filter and wash until neutral; dry at 90℃ for 7 hours; grind and pass through a 300-mesh sieve to obtain a particle size of 65nm and a purity of 98.5%.

[0042] Preparation of carboxyl-based graphene quantum dots: 10g of graphene quantum dots were added to 200mL of deionized water and 0.8g of maleic anhydride were added and ultrasonically dispersed at 250W for 18 minutes; the reaction was stirred at 75℃ for 2.5 hours; after dialyzing with a 3000Da dialysis bag for 30 hours and freeze-drying, the carboxyl content was measured to be 2.0mmol / g and the fluorescence quantum yield was 35%.

[0043] Preparation of organomontmorillonite: 50g of montmorillonite was added to 500mL of deionized water and ultrasonically dispersed for 25 minutes; 5g of cetyltrimethylammonium bromide was added and stirred at 75℃ for 5 hours; centrifugation and washing were carried out until no bromide ions were found, and the interlayer spacing was measured to be 2.2nm.

[0044] Preparation of polyamide-epoxy curing agent: Weigh 30g of polyamide 650 and 10g of epoxy resin E-51, stir and react at 75℃ for 1.5 hours; cool down to 45℃, add 0.3g of dibutyltin dilaurate and continue stirring for 40 minutes. The amine value is measured to be 220mgKOH / g and the pot life is 10 hours.

[0045] This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiment.

[0046] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0047] Example 1

[0048] The coating was prepared according to the following parts by weight: 60 parts of bisphenol A type epoxy resin, 5 parts of amino-graphene-carbon nanotube composite powder, 3 parts of zinc-aluminum-cerium ternary composite phosphate, 3 parts of nano boron nitride / silica core-shell particles, 15 parts of polyamide-epoxy curing agent, 1 part of silane coupling agent KH-560, 5 parts of cashew nut shell oil modified phenolic amine, 0.5 parts of carboxylated graphene quantum dots, 2 parts of organomontmorillonite, 0.1 parts of fluorocarbon surfactant, 8 parts of composite anti-rust pigment (4.8 parts of zinc phosphate, 3.2 parts of aluminum tripolyphosphate, and 2 parts of zinc molybdate), and 10 parts of organic solvent (8 parts of xylene and 2 parts of n-butanol).

[0049] Preparation method

[0050] S1: Add bisphenol A epoxy resin and organic solvent to the dispersion vessel and stir at 800 r / min for 10 minutes to ensure that the resin is completely dissolved in the organic solvent.

[0051] S2: Add aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano-boron nitride / silica core-shell particles, and organomontmorillonite to the dispersion vessel. Heat to 50℃ and disperse at 1500 r / min for 30 minutes; simultaneously, perform ultrasonic-assisted treatment at 300W power for 10 minutes using dual-frequency ultrasonic treatment. After dispersion, take samples for testing: the filler agglomerate particle size ≤100nm, and the dispersion uniformity deviation ≤5%.

[0052] S3: Add silane coupling agent KH-560 to the system and continue stirring at 1500 r / min for 15 minutes to ensure that the coupling agent and the filler react fully.

[0053] S4: Reduce the system temperature to 30℃, add composite rust-preventive pigments and fluorocarbon surfactants, and disperse at 1200r / min for 20 minutes to avoid secondary agglomeration of pigments.

[0054] S5: Add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots to the system, stir at 800 r / min for 15 minutes, and then filter through a 100-mesh filter to obtain the finished coating.

[0055] Finished product performance testing: fineness 40μm, viscosity at 25℃ 800mPa·s.

[0056] Example 2

[0057] The coating was prepared according to the following parts by weight: 70 parts of bisphenol A type epoxy resin, 8 parts of amino-graphene-carbon nanotube composite powder, 5 parts of zinc-aluminum-cerium ternary composite phosphate, 5 parts of nano boron nitride / silica core-shell particles, 20 parts of polyamide-epoxy curing agent, 2 parts of silane coupling agent KH-560, 6 parts of cashew nut shell oil modified phenolic amine, 1.2 parts of carboxylated graphene quantum dots, 3 parts of organomontmorillonite, 0.3 parts of fluorocarbon surfactant, 12 parts of composite anti-rust pigment (7.2 parts of zinc phosphate, 4.8 parts of aluminum tripolyphosphate, and 3 parts of zinc molybdate), and 15 parts of organic solvent (12 parts of xylene and 3 parts of n-butanol).

[0058] Preparation method

[0059] S1: Premixing Resin with Organic Solvent. Add bisphenol A epoxy resin and organic solvent to the dispersion vessel and stir at 900 r / min for 12 minutes to ensure that the resin is completely dissolved.

[0060] S2: Add aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano-boron nitride / silica core-shell particles, and organomontmorillonite. Heat to 55℃ and disperse at 1800 r / min for 35 minutes; simultaneously, perform ultrasonic-assisted treatment at 400W power for 13 minutes using dual-frequency ultrasound. Post-dispersion testing: filler agglomerate particle size ≤90nm, dispersion uniformity deviation ≤4%.

[0061] S3: Add silane coupling agent KH-560 and continue stirring at 1800 r / min for 18 minutes.

[0062] S4: Cool down to 35℃, add composite rust-preventive pigments and fluorocarbon surfactants, and disperse at 1300r / min for 25 minutes.

[0063] S5: Add polyamide-epoxy curing agent, cashew nutshell oil-modified phenolic amine, and carboxylated graphene quantum dots. Stir at 900 r / min for 18 minutes and filter through a 120-mesh filter. Finished product performance testing: fineness 35 μm, viscosity 1000 mPa·s at 25℃.

[0064] Example 3

[0065] The coating was prepared according to the following parts by weight: 80 parts of bisphenol A type epoxy resin, 10 parts of amino graphene-carbon nanotube composite powder, 6 parts of zinc-aluminum-cerium ternary composite phosphate, 6 parts of nano boron nitride / silica core-shell particles, 25 parts of polyamide-epoxy curing agent, 3 parts of silane coupling agent KH-560, 8 parts of cashew nut shell oil modified phenolic amine, 2 parts of carboxylated graphene quantum dots, 4 parts of organomontmorillonite, 0.5 parts of fluorocarbon surfactant, 15 parts of composite anti-rust pigment (9 parts of zinc phosphate, 6 parts of aluminum tripolyphosphate, and 3 parts of zinc molybdate), and 20 parts of organic solvent (16 parts of xylene and 4 parts of n-butanol).

[0066] Preparation method

[0067] S1: Add bisphenol A epoxy resin and organic solvent to the dispersion vessel and stir at 1000 r / min for 15 minutes to ensure that the resin is completely dissolved.

[0068] S2: Add aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano-boron nitride / silica core-shell particles, and organomontmorillonite. Heat to 60℃ and disperse at 2000 r / min for 45 minutes; simultaneously, perform ultrasonic-assisted treatment at 500W power for 15 minutes using dual-frequency ultrasound. Post-dispersion testing: filler agglomerate particle size ≤80nm, dispersion uniformity deviation ≤3%.

[0069] S3: Add silane coupling agent KH-560 and continue stirring at 2000 r / min for 20 minutes.

[0070] S4: Cool down to 40℃, add composite rust-preventive pigments and fluorocarbon surfactants, and disperse at 1500r / min for 30 minutes.

[0071] S5: Add polyamide-epoxy curing agent, cashew nutshell oil-modified phenolic amine, and carboxylated graphene quantum dots. Stir at 1000 r / min for 20 minutes, then filter through a 150-mesh filter. Finished product performance testing: fineness 30 μm, viscosity 1200 mPa·s at 25℃.

[0072] Comparative Example

[0073] The traditional epoxy coating formula is as follows: 70 parts bisphenol A type epoxy resin, 5 parts unmodified graphene, 10 parts zinc phosphate, 20 parts polyamide curing agent, 2 parts silane coupling agent KH-560, and 15 parts organic solvent (12 parts xylene and 3 parts n-butanol).

[0074] Preparation method: Epoxy resin and organic solvent were added to a dispersion vessel and stirred at 900 r / min for 10 minutes; unmodified graphene zinc phosphate was added and dispersed at 1500 r / min for 60 minutes without ultrasonic treatment; silane coupling agent was added and stirred for 15 minutes; curing agent was added and stirred at 900 r / min for 15 minutes; the mixture was filtered through a 120-mesh filter and the fineness was measured to be 80 μm; the viscosity at 25℃ was 900 mPa·s.

[0075] Comparative Example 2

[0076] Raw material formula (parts by weight): 70 parts bisphenol A type epoxy resin, 8 parts unmodified graphene, 5 parts zinc-aluminum-cerium ternary composite phosphate, 5 parts nano boron nitride / silica core-shell particles, 20 parts polyamide-epoxy curing agent, 2 parts silane coupling agent KH-560, 6 parts cashew nut shell oil modified phenolic amine, 1.2 parts carboxylated graphene quantum dots, 3 parts organomontmorillonite, 0.3 parts fluorocarbon surfactant, 12 parts composite anti-rust pigment, and 15 parts organic solvent;

[0077] The unmodified graphene has a sheet diameter of 1-5 μm and a thickness of 0.5-2 nm; the composite anti-rust pigment consists of 7.2 parts zinc phosphate, 4.8 parts aluminum tripolyphosphate, and 3 parts zinc molybdate; the organic solvent consists of 12 parts xylene and 3 parts n-butanol; the specifications of the remaining raw materials are the same as in Example 2.

[0078] Preparation method: S1. Bisphenol A type epoxy resin and organic solvent are added to a dispersion vessel and stirred at 900 r / min for 12 minutes; S2. Unmodified graphene, zinc-aluminum-cerium ternary composite phosphate, nano boron nitride / silica core-shell particles, and organomontmorillonite are added, the temperature is raised to 55℃, and dispersion is carried out at 1800 r / min for 35 minutes, while ultrasonic assisted treatment with 400W power is performed for 13 minutes, using dual-frequency ultrasound with alternating frequencies of 20kHz and 40kHz. The process involves switching the frequency every 10 minutes; in step S3, add silane coupling agent KH-560 and continue stirring at 1800 r / min for 18 minutes; in step S4, cool to 35°C, add composite anti-rust pigment and fluorocarbon surfactant, and disperse at 1300 r / min for 25 minutes; in step S5, add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots, and stir at 900 r / min for 18 minutes, then filter through a 120-mesh filter.

[0079] Performance test results: Fineness 75μm, viscosity at 25℃ 950mPa·s; adhesion 4.2MPa; salt spray resistance 3800 hours; seawater immersion resistance 280 days; high-temperature weight loss rate at 200-250℃ 0.9% / 1000h; Cl － The reaction rate is 0.85 mmol / (g·h); water permeability is 1.5 g / m²·24h; chloride ion permeability is 0.85 mg / m²·d; gloss retention rate is 82% after 1000h of UV aging; there is no fluorescent tracer function; the filler agglomerate particle size is 180 nm.

[0080] Comparative Example 3

[0081] Raw material formula (parts by weight): 70 parts bisphenol A type epoxy resin, 8 parts amino graphene-carbon nanotube composite powder, 5 parts zinc phosphate, 5 parts nano boron nitride / silica core-shell particles, 20 parts polyamide-epoxy curing agent, 2 parts silane coupling agent KH-560, 6 parts cashew nut shell oil modified phenolic amine, 1.2 parts carboxylated graphene quantum dots, 3 parts organomontmorillonite, 0.3 parts fluorocarbon surfactant, 12 parts composite anti-rust pigment, and 15 parts organic solvent;

[0082] The zinc phosphate has a purity of 98%; the amino content of the aminated graphene-carbon nanotube composite powder is 2.0-3.5 mmol / g and the specific surface area is 150-200 m² / g; the composite anti-rust pigment is composed of 7.2 parts zinc phosphate, 4.8 parts aluminum tripolyphosphate, and 3 parts zinc molybdate; the organic solvent is composed of 12 parts xylene and 3 parts n-butanol; the specifications of the remaining raw materials are the same as in Example 2.

[0083] Preparation method: S1. Bisphenol A type epoxy resin and organic solvent are added to a dispersion vessel and stirred at 900 r / min for 12 minutes; S2. Aminated graphene-carbon nanotube composite powder, zinc phosphate, nano boron nitride / silica core-shell particles, and organomontmorillonite are added. The temperature is raised to 55℃, and dispersion is carried out at 1800 r / min for 35 minutes, while ultrasonic assisted treatment with 400W power is performed for 13 minutes. Dual-frequency ultrasonic treatment with alternating frequencies of 20kHz and 40kHz is used. Sound treatment, frequency switching every 10 minutes; S3 add silane coupling agent KH-560, continue stirring at 1800 r / min for 18 minutes; S4 cool to 35℃, add composite anti-rust pigment and fluorocarbon surfactant, disperse at 1300 r / min for 25 minutes; S5 add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots, stir at 900 r / min for 18 minutes, then filter through a 120 mesh filter.

[0084] Performance test results: Fineness 40μm, viscosity at 25℃ 1020mPa·s; adhesion 5.5MPa; salt spray resistance 4500 hours; seawater immersion resistance 320 days; high-temperature weight loss rate at 200-250℃ 0.75% / 1000h; Cl － The reaction rate was 0.4 mmol / (g·h); water permeability was 0.95 g / m²·24h; chloride ion permeability was 0.5 mg / m²·d; gloss retention rate was 83% after 1000h of UV aging; fluorescence intensity decay rate was 8.2% / 1000h at 200-250℃; and filler agglomerate particle size was 95 nm.

[0085] Comparative Example 4

[0086] Raw material formula (parts by weight): 70 parts bisphenol A epoxy resin, 8 parts amino-graphene-carbon nanotube composite powder, 5 parts zinc-aluminum-cerium ternary composite phosphate, 5 parts nano silica, 20 parts polyamide-epoxy curing agent, 2 parts silane coupling agent KH-560, 6 parts cashew nut shell oil modified phenolic amine, 1.2 parts carboxylated graphene quantum dots, 3 parts organomontmorillonite, 0.3 parts fluorocarbon surfactant, 12 parts composite anti-rust pigment, and 15 parts organic solvent;

[0087] The nano-silica has a particle size of 50-100nm; the zinc-aluminum-cerium ternary composite phosphate has a particle size of 50-80nm and a purity of not less than 98%; the composite anti-rust pigment consists of 7.2 parts zinc phosphate, 4.8 parts aluminum tripolyphosphate, and 3 parts zinc molybdate; the organic solvent consists of 12 parts xylene and 3 parts n-butanol; the specifications of the remaining raw materials are the same as in Example 2.

[0088] Preparation method: S1. Bisphenol A type epoxy resin and organic solvent are added to a dispersion vessel and stirred at 900 r / min for 12 minutes; S2. Aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano-silica, and organomontmorillonite are added, the temperature is raised to 55℃, and dispersion is carried out at 1800 r / min for 35 minutes, while simultaneously undergoing ultrasonic assisted treatment with 400W power for 13 minutes, using dual-frequency ultrasonic treatment with alternating frequencies of 20kHz and 40kHz. Sound treatment, frequency switching every 10 minutes; S3 add silane coupling agent KH-560, continue stirring at 1800 r / min for 18 minutes; S4 cool to 35℃, add composite anti-rust pigment and fluorocarbon surfactant, disperse at 1300 r / min for 25 minutes; S5 add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots, stir at 900 r / min for 18 minutes, then filter through a 120 mesh filter.

[0089] Performance test results: Fineness 38μm, viscosity at 25℃ 980mPa·s; adhesion 5.6MPa; salt spray resistance 5200 hours; seawater immersion resistance 370 days; high-temperature weight loss rate at 200-250℃ 1.8% / 1000h; Cl － The reaction rate was 0.88 mmol / (g·h); water permeability was 0.8 g / m²·24h; chloride ion permeability was 0.35 mg / m²·d; gloss retention rate was 84% ​​after 1000h of UV aging; fluorescence intensity decay rate was 8.1% / 1000h at 200-250℃; and filler agglomerate particle size was 92 nm.

[0090] Comparative Example 5

[0091] Raw material formula (parts by weight): 70 parts bisphenol A type epoxy resin, 8 parts amino-graphene-carbon nanotube composite powder, 5 parts zinc-aluminum-cerium ternary composite phosphate, 5 parts nano boron nitride / silica core-shell particles, 20 parts polyamide-epoxy curing agent, 2 parts silane coupling agent KH-560, 6 parts cashew nut shell oil modified phenolic amine, 3 parts organomontmorillonite, 0.3 parts fluorocarbon surfactant, 12 parts composite anti-rust pigment, and 15 parts organic solvent;

[0092] The amino content of the aminated graphene-carbon nanotube composite powder is 2.0-3.5 mmol / g and the specific surface area is 150-200 m² / g; the particle size of the nano boron nitride / silica core-shell particles is 80-120 nm and the silica shell thickness is 10-20 nm; the composite anti-rust pigment is composed of 7.2 parts zinc phosphate, 4.8 parts aluminum tripolyphosphate and 3 parts zinc molybdate; the organic solvent is composed of 12 parts xylene and 3 parts n-butanol; the specifications of the remaining raw materials are the same as in Example 2.

[0093] Preparation method: S1. Bisphenol A type epoxy resin and organic solvent are added to a dispersion vessel and stirred at 900 r / min for 12 minutes; S2. Aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano boron nitride / silica core-shell particles, and organomontmorillonite are added. The temperature is raised to 55℃, and dispersion is carried out at 1800 r / min for 35 minutes, while ultrasonic assisted treatment with 400W power is performed for 13 minutes, using 20kHz and 40kHz frequencies. The mixture is subjected to dual-frequency ultrasonic treatment with alternating frequencies, switching frequencies every 10 minutes; in S3, silane coupling agent KH-560 is added, and stirring is continued at 1800 r / min for 18 minutes; in S4, the temperature is lowered to 35℃, composite anti-rust pigment and fluorocarbon surfactant are added, and the mixture is dispersed at 1300 r / min for 25 minutes; in S5, polyamide-epoxy curing agent and cashew nut shell oil modified phenolic amine are added, and the mixture is stirred at 900 r / min for 18 minutes, and then filtered through a 120-mesh filter.

[0094] Performance test results: Fineness 35μm, viscosity at 25℃ 990mPa·s; adhesion 5.7MPa; salt spray resistance 5300 hours; seawater immersion resistance 360 ​​days; high-temperature weight loss rate at 200-250℃ 0.72% / 1000h; Cl － The reaction rate is 0.86 mmol / (g·h); water permeability is 0.75 g / m²·24h; chloride ion permeability is 0.3 mg / m²·d; gloss retention rate is 62% after 1000h of UV aging; there is no fluorescent tracer function; the particle size of the filler agglomerates is 91 nm.

[0095] The performance comparison between the examples and the comparative examples is shown in the table below:

[0096] Table 1

[0097] Performance indicators Example 1 Example 2 Example 3 Comparative Example Adhesion (MPa) 5.2 5.8 6.0 3.5 Salt spray resistance (hours) 5200 5800 6000 2500 Resistant to seawater immersion (days) 370 400 420 180 High-temperature weight loss rate (% / 1000h) 0.8 0.7 0.6 2.5 Resistance to cathode stripping (hours) 1100 1300 1500 600

[0098] The mechanical properties and resistance to media penetration of the coatings in the examples and comparative examples are compared in the table below:

[0099] Table 2

[0100] index Example 1 Example 2 Example 3 Comparative Example Tensile strength (MPa) 32.5 35.8 38.2 22.3 Elongation at break (%) 4.8 5.2 5.5 2.1 Hardness (pencil hardness) 3H 3H 4H 2H Water permeability (g / m²·24h) 0.85 0.72 0.68 2.56 Chloride ion permeability (mg / m²·d) 0.32 0.28 0.25 1.85

[0101] The following table compares the anti-bioadhesion and weathering resistance of the coatings in the examples and comparative examples:

[0102] Table 3

[0103] index Example 1 Example 2 Example 3 Comparative Example Marine diatom attachment quantity (diatoms / cm²) 12.5 10.2 8.8 45.6 UV aging resistance (gloss retention rate after 1000h, %) 82.3 85.6 88.5 52.8 Resistance to damp heat aging (adhesion retention rate after 500h, %) 90.5 93.2 95.8 65.3 Surface resistivity of coating (Ω·cm) 1.2×10¹² 1.5×10¹² 1.8×10¹² <![CDATA[3.5×10¹ 0 ]]> Impact strength (kg·cm) 50 55 60 30

[0104] The performance comparison between Example 2 and Comparative Examples 2-5 is shown in the table below:

[0105] Table 4

[0106] Performance indicators Example 2 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Fineness (μm) 35 75 40 38 35 Viscosity at 25℃ (mPa·s) 1000 950 1020 980 990 Adhesion (MPa) 5.8 4.2 5.5 5.6 5.7 Salt spray resistance (hours) 5800 3800 4500 5200 5300 Resistant to seawater immersion (days) 400 280 320 370 360 High-temperature weight loss rate (% / 1000h) 0.7 0.9 0.75 1.8 0.72 <![CDATA[Cl － Reaction rate (mmol / (g·h)) 0.9 0.85 0.4 0.88 0.86 Water permeability (g / m²·24h) 0.72 1.5 0.95 0.8 0.75 Chloride ion permeability (mg / m²·d) 0.28 0.85 0.5 0.35 0.3 UV aging resistance gloss retention rate (%) 85.6 82 83 84 62 Fluorescence intensity decay rate (% / 1000h) 8 none 8.2 8.1 none Filler agglomerate particle size (nm) 90 180 95 92 91 Fluorescence tracer function have none have have none

[0107] Compared with the comparative example using unmodified graphene, single anti-rust pigment and traditional curing system, this invention achieves a qualitative leap in the corrosion resistance, mechanical properties and resistance to extreme environments of marine heavy-duty anti-corrosion epoxy coatings through an integrated design of modified graphene reinforcement, multi-functional filler synergy and optimized curing process. It completely solves the core pain points of traditional coatings, such as "short anti-corrosion cycle, fast penetration, poor biological resistance and weak weather resistance".

[0108] In terms of core anti-corrosion and adhesion performance, the embodiment achieves an adhesion of 5.2-6.0 MPa, which is 1.5-1.7 times that of the comparative example, thanks to the synergistic effect of aminated graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, and nano boron nitride / silica core-shell particles. The salt spray resistance is 5200-6000 hours, and the seawater immersion resistance is 370-420 days, which are 1.1-1.4 times higher than the comparative example, respectively. The high temperature weight loss rate is 0.6-0.8% / 1000h, and the cathodic disbondment resistance is 1100-1500 hours, which perfectly meets the long-term protection requirements of marine high-salt, high-temperature, and cathodic protection environments.

[0109] In terms of mechanical and anti-permeability properties, the embodiment optimizes the coating density with organomontmorillonite, achieving a tensile strength of 32.5-38.2 MPa, an elongation at break of 4.8-5.5%, and a hardness of 3H-4H, significantly improving mechanical toughness. The water permeability is 0.68-0.85 g / m²·24h, and the chloride ion permeability is 0.25-0.32 mg / m²·d, which is only 1 / 3-1 / 4 of the comparative example, effectively blocking the penetration of corrosive media and solving the problem of traditional coatings being easily corroded by ions.

[0110] Regarding anti-bioadhesion and weather resistance, the fluorocarbon surfactants in this embodiment impart anti-bioadhesion capabilities, with marine diatom adhesion amounting to only 8.8-12.5 diatoms / cm². Carboxylated graphene quantum dots optimize weather resistance, maintaining a gloss retention rate of 82.3-88.5% after 1000h UV aging and an adhesion retention rate of 90.5-95.8% after 500h damp heat aging, with an impact strength of 50-60 kg·cm. At the same time, high surface resistance ensures insulation, completely solving the defects of traditional coatings that lack anti-bioadhesion function and are prone to weather failure.

[0111] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments, characterized in that, It is composed of the following raw materials in parts by weight: 60-80 parts of bisphenol A type epoxy resin, 5-10 parts of amino graphene-carbon nanotube composite powder, 3-6 parts of zinc-aluminum-cerium ternary composite phosphate, 3-6 parts of nano boron nitride / silica core-shell particles, 15-25 parts of polyamide-epoxy curing agent, 1-3 parts of silane coupling agent KH-560, 5-8 parts of cashew nut shell oil modified phenolic amine, 0.5-2 parts of carboxylated graphene quantum dots, 2-4 parts of organomontmorillonite, 0.1-0.5 parts of fluorocarbon surfactant, 8-15 parts of composite anti-rust pigment, and 10-20 parts of organic solvent; The carboxyl content is 1.5-2.5 mmol / g; The preparation process of the organomontmorillonite involves modification with hexadecyltrimethylammonium bromide. Montmorillonite is added to deionized water and ultrasonically dispersed. Then, 8-12% of hexadecyltrimethylammonium bromide is added, the temperature is raised to 70-80°C, and the mixture is stirred to react. After the reaction is completed, the mixture is centrifuged, washed with deionized water until no bromide ions are detected, and dried at 60-80°C for 8-10 hours. The composite anti-rust pigment is composed of zinc phosphate, aluminum tripolyphosphate, and zinc molybdate in a mass ratio of 3:2:

1.

2. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, It also includes the preparation process of amino-graphene-carbon nanotube composite powder: weigh graphene and carbon nanotubes at a mass ratio of 5:1, add deionized water, then add 1-2% nitric acid of total mass, and ultrasonically disperse for 30-60 minutes; add 5-8% 3-aminopropyltriethoxysilane of total mass, heat to 60-70℃, stir and react, filter after the reaction is completed, calcine the obtained solid at 600-800℃ for 2-3 hours under nitrogen protection, cool, grind and pass through a 200-mesh sieve; the obtained composite powder has an amino content of 2.0-3.5 mmol / g and a specific surface area of ​​150-200 m² / g.

3. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, It also includes the preparation process of nano-boron nitride / silica core-shell particles: nano-boron nitride is added to ethanol and ultrasonically dispersed for 20-30 minutes. Tetraethyl orthosilicate (10-15% by mass) is added dropwise to the dispersion, and 0.5-1% ammonia is added to adjust the pH to 8.0-9.

0. The temperature is raised to 50-60℃, and the reaction is stirred. After the reaction is completed, the particles are separated by centrifugation, and the obtained solid is dried at 60-80℃. The obtained core-shell particles have a particle size of 80-120 nm and a silica shell thickness of 10-20 nm.

4. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, It also includes the preparation process of zinc-aluminum-cerium ternary composite phosphate; zinc nitrate, aluminum nitrate, and cerium nitrate are weighed in a mass ratio of 2:1:1, dissolved in deionized water to prepare a 0.5-1 mol / L mixed solution, 1-2 mol / L phosphoric acid solution is added dropwise to the mixed solution, the pH is adjusted to 3.0-4.0, the temperature is raised to 50-60℃, the reaction is stirred, the solid is obtained by filtration after the reaction is completed, washed with deionized water until neutral, dried at 80-100℃, ground and passed through a 300-mesh sieve; the obtained product has a particle size of 50-80 nm and a purity of not less than 98%.

5. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, It also includes the preparation process of carboxylated graphene quantum dots; weigh the graphene quantum dots, add deionized water, then add maleic anhydride accounting for 5-10% of the total mass, ultrasonically disperse for 15-20 minutes, heat to 70-80℃, stir to react, after the reaction is completed, perform dialysis treatment, the molecular weight cutoff of the dialysis bag is 3000 Da, the dialysis time is 24-36 hours, and then freeze-dry.

6. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, It also includes the preparation process of polyamide-epoxy curing agent; weigh polyamide 650 and epoxy resin E-51 at a mass ratio of 3:1, mix them, heat to 70-80℃, stir and react for 1-2 hours, cool to 40-50℃, add 0.5-1% of dibutyltin dilaurate by mass, and continue stirring for 30-45 minutes; the amine value of the obtained curing agent is 200-250mgKOH / g, and the pot life is 8-12 hours.

7. A method for preparing a graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments as described in claim 1, characterized in that, Includes the following steps: S1: Add bisphenol A epoxy resin and organic solvent to the dispersion vessel and stir at 800-1000 r / min for 10-15 minutes; S2: Add amino-graphene-carbon nanotube composite powder, zinc-aluminum-cerium ternary composite phosphate, nano boron nitride / silica core-shell particles, and organomontmorillonite. Heat to 50-60℃ and disperse at 1500-2000r / min for 30-45 minutes. Simultaneously, perform ultrasonic-assisted treatment for 10-15 minutes with an ultrasonic power of 300-500W. S3: Add silane coupling agent KH-560 and continue stirring for 15-20 minutes; S4: Cool down to 30-40℃, add composite rust-preventive pigments and fluorocarbon surfactants, and disperse at a speed of 1200-1500r / min for 20-30 minutes; S5: Add polyamide-epoxy curing agent, cashew nut shell oil modified phenolic amine, and carboxylated graphene quantum dots, stir at 800-1000 r / min for 15-20 minutes, and then filter through a 100-150 mesh filter to obtain the finished coating; the fineness of the finished product is no greater than 50 μm, and the viscosity at 25℃ is 800-1200 mPa·s.

8. The method for preparing graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 7, characterized in that, The dispersion process in step S2 uses dual-frequency ultrasonic treatment, that is, 20kHz and 40kHz frequencies are used alternately, and the frequency is switched every 10 minutes. After the dispersion is completed, samples are taken for testing. The particle size of the filler agglomerates is no greater than 100nm, and the dispersion uniformity deviation is no greater than 5%.

9. The graphene-reinforced heavy-duty anti-corrosion epoxy coating for marine environments according to claim 1, characterized in that, The organic solvent is a mixture of xylene and n-butanol in a volume ratio of 4:

1. The zinc-aluminum-cerium ternary composite phosphate reacts with corrosion ions to generate ZnCl2, AlCl3, CeCl3, and PO4. 3- ; The epoxy value of bisphenol A type epoxy resin is 0.51 eq / 100g.

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