Multi-specification composite graphene modified anticorrosive and antifouling paint and preparation method thereof

Abstract

The application discloses a multi-specification composite graphene modified anticorrosive and antifouling paint and a preparation method thereof, raw materials of the paint include gradient composite powder, resin matrix, hydrophobic additive, solvent, curing agent and functional additive; the gradient composite powder is compounded by 20-30% of less-layer ternary composite powder and 70-80% of more-layer ternary composite powder, and the ternary composite powder includes graphene, a polypyrrole coating layer and silver nanoparticles loaded on the polypyrrole coating layer. The polypyrrole coating is used to solve the dispersion problem of the graphene and endow the coating layer with an electrochemical anticorrosion function, the silver nanoparticles are loaded to endow the coating layer with antibacterial and antifouling capacity, the multi-specification graphene gradient compounding establishes a multi-level compact barrier network, and the hydrophobic additive and the multi-level powder form a biomimetic micro-nano rough hydrophobic structure. The obtained paint has excellent physical barrier anticorrosion, electrochemical anticorrosion, antibacterial and antifouling and high hydrophobic self-cleaning performances, and has outstanding comprehensive protection capacity, and can be widely used in long-term protection under harsh corrosive environments such as marine engineering, ships and steel structures.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating preparation technology, specifically to a multi-specification composite graphene-modified anti-corrosion and anti-fouling coating and its preparation method. Background Technology

[0002] In marine environments, outdoor industrial atmospheres, and humid and corrosive conditions, steel structures, ship equipment, and pipeline facilities are highly susceptible to electrochemical corrosion, scaling, and marine organism contamination, which severely shorten equipment lifespan and increase maintenance costs. Therefore, high-performance anti-corrosion and anti-fouling coatings are a core research direction in the field of industrial protection.

[0003] Graphene possesses an ultra-high specific surface area, excellent mechanical properties, gas barrier properties, and chemical stability, making it an ideal filler for coating modification. It can form a physical barrier network within the coating, effectively blocking the penetration of water vapor, oxygen, and corrosive ions, significantly improving the anti-corrosion performance of the coating. However, pure graphene powder exhibits extremely strong lamellar van der Waals forces, making it prone to agglomeration and accumulation in resin systems. This leads to increased coating porosity and decreased mechanical properties, ultimately reducing the anti-corrosion effect. Furthermore, pure graphene coatings have limited hydrophobic properties, making their surfaces susceptible to staining and microbial growth, resulting in insufficient antifouling and self-cleaning properties, which makes them unsuitable for use in harsh marine and industrial corrosive environments.

[0004] In existing technologies, single-modified graphene coatings generally have the following defects: First, they only use graphene of a single size and a single number of layers for doping, resulting in a simple barrier structure with permeation channels and poor long-term corrosion resistance; second, they lack conductive polymer modification and antibacterial function modification, so the coatings do not have electrochemical corrosion resistance and antibacterial and antifouling capabilities, and are prone to seaweed and bacterial contamination in marine environments; third, the coating surface is hydrophilic, prone to scale buildup, and has weak self-cleaning performance. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing graphene anti-corrosion coatings, this invention provides a multi-specification composite graphene-modified anti-corrosion and anti-fouling coating and its preparation method. Through multi-specification graphene gradient doping, polypyrrole conductive polymer coating, silver nanoparticle loading, and biomimetic hydrophobic structure construction, a high-performance, multifunctional, and highly stable anti-corrosion and anti-fouling coating is prepared.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a multi-specification composite graphene-modified anti-corrosion and anti-fouling coating, comprising, by weight, the following raw materials: 3-8 parts of gradient composite powder; 60-75 parts of resin matrix; 2-4 parts of hydrophobic additive; 15-25 parts of solvent; 5-10 parts of curing agent; and 1-3 parts of functional additive; wherein the gradient composite powder is composed of a few-layer ternary composite powder and a multi-layer ternary composite powder, wherein the few-layer ternary composite powder accounts for 20%-30% by weight and the multi-layer ternary composite powder accounts for 70%-80% by weight; wherein the ternary composite powder comprises graphene, a polypyrrole layer coated on the surface of graphene, and silver nanoparticles loaded on the polypyrrole layer.

[0007] Furthermore, the graphene in the few-layer ternary composite powder is few-layer graphene with 1-5 layers and a particle size of 0.5-2 μm; the graphene in the multi-layer ternary composite powder is multi-layer graphene with 6-15 layers and a particle size of 3-8 μm.

[0008] Furthermore, the resin matrix is ​​any one or more of epoxy resin, polyurethane resin, and acrylic resin; the hydrophobic additive is fluorinated modified acrylate or organosilicon hydrophobic additive; the solvent is a xylene-butyl acetate-ethanol mixed solvent; and the functional additives include leveling agents, defoamers, and dispersants.

[0009] On the other hand, a method for preparing the multi-specification composite graphene-modified anti-corrosion and anti-fouling coating includes the following steps: S1: Selecting few-layer graphene and multi-layer graphene, pretreating them respectively to obtain hierarchical graphene powder; S2: Dispersing the hierarchical graphene powder in an acidic aqueous solution, adding pyrrole monomer, and adding an oxidant under low-temperature stirring conditions to initiate an in-situ polymerization reaction. The reaction product is centrifuged, washed, and dried to obtain polypyrrole-coated modified graphene powder; S3: Dispersing the polypyrrole-coated modified graphene powder in an ethanol-water mixed solvent. In step S4, silver salt precursor and stabilizer are added, and silver nanoparticles are in situ loaded on the surface of polypyrrole coating through reduction reaction to obtain ternary composite functional powder; Step S5: Ternary composite functional powder corresponding to few-layer graphene and ternary composite functional powder corresponding to multi-layer graphene are compounded and mixed in proportion, and dispersed by high-speed shearing to obtain gradient composite powder; Step S6: The gradient composite powder, resin matrix, hydrophobic additive, solvent, curing agent and functional additive are mixed, stirred, milled and filtered to obtain the multi-specification composite graphene modified anti-corrosion and anti-fouling coating.

[0010] Furthermore, in S1, the pretreatment method is as follows: add anhydrous ethanol and ultrasonically disperse for 20-40 min, ultrasonic power 300-500W, dispersion temperature 25-35℃, then vacuum dry at 80-100℃ for 6-8 h, and grind through a 300-500 mesh sieve.

[0011] Furthermore, in S2, the acidic aqueous solution is a hydrochloric acid solution with a concentration of 0.1-0.3 mol / L; the oxidant is ammonium persulfate; the solid-liquid ratio of the hierarchical graphene powder to the acidic aqueous solution is 1:(40-60) g / mL; the mass ratio of the hierarchical graphene powder to pyrrole monomer is (10-15):1; the molar ratio of the oxidant to pyrrole monomer is (1.2-1.5):1; the temperature of the in-situ polymerization reaction is 0-5℃, the stirring speed is 300-500 r / min, and the reaction time is 4-6 h.

[0012] Furthermore, in S3, the volume ratio of ethanol to deionized water in the ethanol-water mixed solvent is (2-3):1; the silver salt precursor is silver nitrate, and its addition amount is 2%-5% of the mass of polypyrrole-coated modified graphene powder; the stabilizer is polyvinylpyrrolidone, and its addition amount is 0.5%-1% of the mass of the silver salt precursor; the reduction reaction uses hydrazine hydrate as the reducing agent, the reduction temperature is 40-60℃, the reaction time is 2-3h, and the stirring speed is 400-600r / min.

[0013] Furthermore, in step S4, after compounding, a dispersant is added, and the high-speed shear dispersion is performed at a speed of 8000-10000 r / min for 15-25 min.

[0014] Furthermore, step S5 is followed by step S6, which involves construction and curing: the obtained multi-specification composite graphene modified anti-corrosion and anti-fouling coating is sprayed or brushed onto the substrate surface, with a single coating thickness of 20-30 μm. After surface drying at room temperature, it is cured at a constant temperature of 60-80℃ for 2-4 hours to form a coating. The coating has a biomimetic micro-nano rough hydrophobic surface with a water contact angle ≥115°.

[0015] The multi-specification composite graphene-modified anti-corrosion and anti-fouling coating of the present invention has the following beneficial effects: 1. In-situ coating with polypyrrole effectively overcomes the agglomeration problem of graphene sheets in the resin system, improving the uniformity of powder dispersion and compatibility with the resin matrix. At the same time, by utilizing the differences in particle size and number of layers between few-layer graphene and multi-layer graphene for gradient compounding, a multi-level stacked structure is formed inside the coating, with few layers filling micropores and multiple layers constructing a macroscopic barrier skeleton. This significantly reduces the porosity of the coating, significantly extends the penetration path of corrosive media, and the physical barrier performance far exceeds that of single-specification graphene coatings.

[0016] 2. The polypyrrole coating not only enhances the lamellar barrier effect but also endows the coating with electrochemical protection, further improving corrosion resistance by inhibiting the electrochemical corrosion reaction of the metal substrate. This dual effect of physical barrier and electrochemical protection enables the coating to exhibit excellent long-term protective performance in harsh corrosive environments such as salt spray, humid heat, and acid / alkali conditions.

[0017] 3. Silver nanoparticles loaded in situ on the surface of the polypyrrole coating have a broad-spectrum killing and inhibitory effect on common polluting microorganisms such as marine bacteria and algae. This can fundamentally prevent the adhesion and growth of microorganisms on the coating surface, making up for the shortcomings of traditional graphene coatings in lacking biofouling resistance.

[0018] 4. The multi-level particle size gradient composite powder and the low surface energy hydrophobic additive work synergistically during the coating film formation process to spontaneously construct a biomimetic micro-nano rough hydrophobic structure on the coating surface, giving the coating high hydrophobicity and self-cleaning function. Water droplets are not easy to spread, and dirt and seawater can automatically slide off, effectively reducing pollutants and biological adhesion.

[0019] 5. Polypyrrole coating modification effectively improves the interfacial bonding between graphene and resin matrix. After the coating is cured, it has strong adhesion and good flexibility, and is not easy to crack or fall off. It can maintain structural integrity and stable protective function during long-term service, and its service life is significantly extended. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments 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.

[0021] This invention provides a multi-specification composite graphene-modified anti-corrosion and anti-fouling coating, which achieves anti-corrosion, anti-fouling, and self-cleaning functions by combining a ternary composite powder with a resin matrix and other raw materials.

[0022] The multi-specification composite graphene-modified anti-corrosion and anti-fouling coating comprises, by weight, the following raw materials: 3-8 parts of gradient composite powder, 60-75 parts of resin matrix, 2-4 parts of hydrophobic additive, 15-25 parts of solvent, 5-10 parts of curing agent, and 1-3 parts of functional additive; the gradient composite powder is the core functional filler of this invention, and is composed of a few-layer ternary composite powder and a multi-layer ternary composite powder, wherein the few-layer ternary composite powder accounts for 20%-30% by weight and the multi-layer ternary composite powder accounts for 70%-80% by weight; the ternary composite powder further comprises graphene, a polypyrrole layer coated on the surface of graphene, and silver nanoparticles loaded on the polypyrrole layer. This coating employs a specific composition and gradient compounding method, enabling the establishment of a multi-level barrier network within the coating: the small-layer graphene sheets fill the microscopic pores of the coating; the larger-layer graphene sheets act as a macroscopic framework, working together to completely block the penetration channels of water vapor, oxygen, and corrosive ions. The polypyrrole layer effectively isolates the graphene sheets, overcoming their tendency to agglomerate in the resin, significantly improving the powder's dispersion uniformity and compatibility with the resin matrix. Furthermore, polypyrrole itself is conductive, forming conductive pathways within the coating and imparting electrochemical corrosion protection, inhibiting electrochemical corrosion through anodic passivation or cathodic protection of the metal substrate. The loading of silver nanoparticles adds broad-spectrum antibacterial capabilities, killing or inhibiting the attachment and growth of marine bacteria, algae, and other microorganisms. The organic combination of these three functional components allows the gradient composite powder to simultaneously possess physical barrier, electrochemical protection, and antibacterial and antifouling properties. The amount of gradient composite powder should be controlled between 3 and 8 parts. This ensures that there are enough functional components in the coating to establish a complete barrier and protective network, while avoiding the problem of the coating becoming brittle and the adhesion decreasing due to excessive powder addition. If the amount is less than 3 parts, it is difficult to form an effective multi-level barrier structure; if it is more than 8 parts, although the coating has good density, its flexibility and adhesion to the substrate may deteriorate, and the cost will increase.

[0023] The graphene in the few-layer ternary composite powder consists of 1-5 layers with a particle size of 0.5-2 μm; the graphene in the multi-layer ternary composite powder consists of 6-15 layers with a particle size of 3-8 μm. Gradual combination of these two types of graphene, which differ significantly in both layer count and particle size, achieves a more ideal multi-level filling and stacking effect. The few-layer, small-particle-size graphene more easily penetrates the tiny voids generated during coating formation and the gaps in the resin cross-linking network, providing a fine sealing effect; while the multi-layer, large-particle-size graphene sheets have a higher flexural modulus and overlap in the coating to form a strong and tough barrier framework, significantly increasing the tortuosity of the diffusion path of corrosive media. This reasonable combination of particle size and layer count is one of the keys to the significant improvement in corrosion resistance and durability of this invention.

[0024] The resin matrix is ​​any one or more of epoxy resin, polyurethane resin, and acrylic resin; these resins are all film-forming substances commonly used in industrial anti-corrosion coatings, and have good compatibility with the modified graphene powder of this invention, which can ensure the basic mechanical properties of the coating and the adhesion to the substrate.

[0025] The hydrophobic additive is a fluorinated modified acrylate or an organosilicon hydrophobic additive. These two additives have extremely low surface energy and will accumulate on the surface during the coating film formation process. They work together with the multi-level particle size lamellar structure in the gradient composite powder to construct a micro-nano rough hydrophobic structure similar to the surface of a lotus leaf on the coating surface, thereby giving the coating high hydrophobicity and self-cleaning function.

[0026] The solvent is a xylene-butyl acetate-ethanol mixed solvent; the volume ratio of the three is (4-6):(3-5):(1-2). This mixed solvent has good dissolving ability for the resin matrix and a suitable evaporation gradient, which is beneficial to coating leveling and dense film formation.

[0027] The functional additives include leveling agents, defoamers, and dispersants. Specifically, the leveling agent is a polyether-modified organosiloxane (such as BYK-333, BYK-306); the defoamer is a polysiloxane defoamer (such as BYK-066N); and the dispersant is a high molecular weight block copolymer solution (such as BYK-2150). These are common additives used in coating production to improve the application performance and appearance of the coating. The specific selection and dosage of each additive can be adjusted by those skilled in the art based on the actual conditions of the resin system.

[0028] The preparation method of the multi-specification composite graphene modified anti-corrosion and anti-fouling coating includes the following steps: S1: Select few-layer graphene and multi-layer graphene, and pretreat them separately to obtain graded graphene powder. The pretreatment method is as follows: add the few-layer graphene and multi-layer graphene to anhydrous ethanol and ultrasonically disperse for 20-40 min, with an ultrasonic power of 300-500 W and a dispersion temperature of 25-35℃, then vacuum dry at 80-100℃ for 6-8 h, and grind through a 300-500 mesh sieve. Ultrasonic dispersion ensures that the two types of graphene are fully exfoliated and dispersed; vacuum drying thoroughly removes ethanol and adsorbed trace amounts of moisture; grinding and sieving remove a small amount of hard agglomerates and large particles that may have formed during ultrasonication and drying, resulting in graded graphene powder with uniform particle size and high purity.

[0029] S2: The graded graphene powder is dispersed in an acidic aqueous solution, pyrrole monomer is added, and an oxidant is added under low-temperature stirring conditions to initiate an in-situ polymerization reaction. The reaction product is centrifuged, washed, and dried to obtain polypyrrole-coated modified graphene powder. This step involves in-situ oxidative polymerization of pyrrole monomer on the surface of graphene sheets to form a uniform, conductive polypyrrole coating layer on the graphene surface. The acidic environment is conducive to the full dissolution of pyrrole monomer and the directional polymerization reaction. At the same time, it allows for appropriate protonation doping of the graphene sheets, improving their interfacial bonding with polypyrrole.

[0030] S3: The polypyrrole-coated modified graphene powder is dispersed in an ethanol-water mixed solvent, and a silver salt precursor and stabilizer are added. Silver nanoparticles are then in-situ loaded onto the surface of the polypyrrole coating through a mild reduction reaction to obtain a ternary composite functional powder. This step further loads silver nanoparticles onto the surface of the polypyrrole coating to generate the ternary composite functional powder. The nitrogen atoms and conjugated structure abundant in the polypyrrole backbone have a strong adsorption and coordination ability for silver ions, which provides favorable conditions for the site-specific and uniform nucleation and growth of silver nanoparticles on the surface of the polypyrrole coating, effectively avoiding the spontaneous aggregation and detachment of silver particles.

[0031] S4: The ternary composite functional powder corresponding to few-layer graphene and the ternary composite functional powder corresponding to multi-layer graphene are compounded and mixed in a certain proportion, a dispersant is added, and high-speed shear dispersion is performed at a speed of 8000-10000 r / min for 15-25 min to obtain gradient composite powder. The strong shear force can effectively open up the soft agglomerates that may be formed in the powder during the drying process, so that the powders of different particle sizes and number of layers can be uniformly mixed at the microscale, creating a prerequisite for the formation of multi-level barrier structures in the coating.

[0032] S5: The gradient composite powder, resin matrix, hydrophobic additive, solvent, curing agent and functional additive are mixed, and then stirred, milled and filtered to obtain the multi-specification composite graphene modified anti-corrosion and anti-fouling coating.

[0033] S6: Construction and Curing: The obtained multi-specification composite graphene-modified anti-corrosion and anti-fouling coating is sprayed or brushed onto the substrate surface, with a single coating thickness of 20-30μm. After surface drying at room temperature, it is cured at a constant temperature of 60-80℃ for 2-4 hours to form a coating. During this process, as the solvent evaporates and the resin cross-links and cures, the multi-level particle size sheets in the gradient composite powder naturally oriented and stacked in the coating. At the same time, low surface energy hydrophobic additives migrate to the coating surface. The two work together to spontaneously form a biomimetic micro-nano rough hydrophobic structure on the coating surface, so that the water contact angle of the cured coating can reach more than 115°. This surface structure makes it difficult for water droplets to spread, causing them to slide off in the form of beads, carrying away surface dust and dirt, achieving a self-cleaning function, and reducing the adhesion of dirt and marine organisms from the source.

[0034] In S2, the acidic aqueous solution is a hydrochloric acid solution with a concentration of 0.1-0.3 mol / L; the solid-liquid ratio of the hierarchical graphene powder to the acidic aqueous solution is 1:(40-60) g / mL; to ensure that the graphene is fully suspended in the liquid phase, providing sufficient reaction space for pyrrole polymerization. The mass ratio of the hierarchical graphene powder to the pyrrole monomer is (10-15):1; to control the thickness and uniformity of the polypyrrole coating layer. If the ratio is too large (too little pyrrole), the coating will be incomplete; if the ratio is too small (too much pyrrole), free polypyrrole particles may be generated, reducing the effective coating efficiency and increasing the difficulty of post-processing. The oxidant is ammonium persulfate; the molar ratio of the oxidant to the pyrrole monomer is (1.2-1.5):1; a slight excess of oxidant can ensure complete pyrrole polymerization, but will not cause side reactions due to excessive excess. The in-situ polymerization reaction is carried out at a temperature of 0-5℃ (e.g., an ice-water bath), a stirring speed of 300-500 r / min, and a reaction time of 4-6 h. Low-temperature in-situ polymerization can effectively control the reaction rate, allowing the polypyrrole molecular chains to grow slowly and in a relatively ordered manner on the graphene surface, resulting in a dense and uniform polypyrrole coating layer. This avoids uneven coating or local agglomeration caused by excessively vigorous reactions at room temperature or high temperature. After the reaction, the product is preferably washed with deionized water and ethanol alternately by centrifugation until the washing liquid is neutral, and then vacuum dried at around 80℃ to thoroughly remove residual monomers, oligomers, and salts, obtaining pure polypyrrole-coated modified graphene powder.

[0035] In S3, the volume ratio of ethanol to deionized water in the ethanol-water mixed solvent is (2-3):1. This ratio of mixed solvent ensures good dispersion of the modified graphene powder and facilitates the dissolution of the silver salt precursor. Simultaneously, the presence of ethanol helps reduce the reduction reaction rate, allowing the silver particles to be uniformly loaded at a smaller size. The silver salt precursor is silver nitrate, added at 2%-5% of the mass of the polypyrrole-coated modified graphene powder. This ensures that the final silver nanoparticle loading provides sufficient antibacterial effect without significantly increasing costs or affecting the stability of the conductive network of the coating due to excessive silver content. The stabilizer is polyvinylpyrrolidone (PVP), added at 0.5%-1% of the mass of the silver salt precursor. PVP prevents secondary aggregation of the generated silver nanoparticles through steric hindrance. The reduction reaction uses hydrazine hydrate as the reducing agent, with a reduction temperature of 40-60℃, a reaction time of 2-3 hours, and a stirring speed of 400-600 r / min. Hydrazine hydrate has moderate reducing power and can stably reduce silver ions to elemental silver particles within this temperature range. After the reaction, the graphene / polypyrrole / silver nanoparticle ternary composite functional powder is obtained through centrifugation, washing, and drying. The reducing agent hydrazine hydrate should be added slowly to control the nucleation rate.

[0036] The following specific embodiments and comparative examples further illustrate the implementation methods and effects of the present invention.

[0037] Example 1 This example provides a method for preparing multi-specification composite graphene-modified anti-corrosion and anti-fouling coatings, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, and multi-layer graphene with 6-10 layers and an average particle size of about 5 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0038] S2. Take 10g of pretreated few-layer graphene powder and 10g of pretreated multilayer graphene powder, respectively, and add them to 500mL of 0.2mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 1.0g of pyrrole monomer to each. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.3 times that of the pyrrole monomer. After the addition is complete, continue the reaction for 5h. The products are separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder and multilayer polypyrrole-coated modified graphene powder, respectively.

[0039] S3. Disperse 8g of the above-mentioned few-layer polypyrrole-coated modified graphene powder and 8g of the above-mentioned multilayer polypyrrole-coated modified graphene powder in 200mL of a mixed solvent of ethanol and water with a volume ratio of 2.5:1. Add 0.24g of silver nitrate and 0.002g of polyvinylpyrrolidone to each, stir evenly, and heat to 50℃. While stirring, slowly add a dilute solution of hydrazine hydrate for reduction. Keep the reaction at this temperature for 2.5h. After cooling, centrifuge, wash, and dry to obtain few-layer ternary composite functional powder and multilayer ternary composite functional powder, respectively.

[0040] S4. Mix the few-layer ternary composite functional powder and the multi-layer ternary composite functional powder at a mass ratio of 25:75, add about 0.5g of dispersant (BYK-2150), and disperse at high speed at 9000r / min for 20min to obtain gradient composite powder.

[0041] S5. By weight, take 5 parts of gradient composite powder, 70 parts of epoxy resin, 3 parts of silicone hydrophobic additive, 20 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 7 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0042] S6. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0043] Example 2 This example provides a method for preparing multi-specification composite graphene-modified anti-corrosion and anti-fouling coatings, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 0.8 μm, and multi-layer graphene with 8-15 layers and an average particle size of about 6 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0044] S2. Take 12g of pretreated few-layer graphene powder and 12g of pretreated multilayer graphene powder respectively, and add them to 600mL of 0.15mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 0.9g of pyrrole monomer to each. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.4 times that of pyrrole monomer. After the addition is complete, continue the reaction for 6h. The products are separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder and multilayer polypyrrole-coated modified graphene powder respectively.

[0045] S3. Disperse 10g of the above-mentioned few-layer polypyrrole-coated modified graphene powder and 10g of the above-mentioned multilayer polypyrrole-coated modified graphene powder in 250mL of a mixed solvent of ethanol and water in a volume ratio of 3:1. Add 0.3g of silver nitrate and 0.003g of polyvinylpyrrolidone to each, stir evenly, and heat to 50℃. While stirring, slowly add a dilute solution of hydrazine hydrate for reduction. Keep the reaction at this temperature for 2.5h. After cooling, centrifuge, wash, and dry to obtain few-layer ternary composite functional powder and multilayer ternary composite functional powder, respectively.

[0046] S4. Mix the few-layer ternary composite functional powder and the multi-layer ternary composite functional powder at a mass ratio of 30:70, add about 0.5g of dispersant (BYK-2150), and disperse at high speed at 9000r / min for 20min to obtain gradient composite powder.

[0047] S5. By weight, take 6 parts of gradient composite powder, 68 parts of polyurethane resin, 2.5 parts of fluorine-modified acrylate hydrophobic additive, 18 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 8 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0048] S6. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 22μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0049] Example 3 This example provides a method for preparing multi-specification composite graphene-modified anti-corrosion and anti-fouling coatings, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, and multi-layer graphene with 6-10 layers and an average particle size of about 5 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0050] S2. Take 10g of pretreated few-layer graphene powder and 10g of pretreated multilayer graphene powder, respectively, and add them to 500mL of 0.2mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 1.0g of pyrrole monomer to each. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.3 times that of the pyrrole monomer. After the addition is complete, continue the reaction for 5h. The products are separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder and multilayer polypyrrole-coated modified graphene powder, respectively.

[0051] S3. Disperse 8g of the above-mentioned few-layer polypyrrole-coated modified graphene powder and 8g of the above-mentioned multilayer polypyrrole-coated modified graphene powder in 200mL of a mixed solvent of ethanol and water with a volume ratio of 2.5:1. Add 0.24g of silver nitrate and 0.002g of polyvinylpyrrolidone to each, stir evenly, and heat to 50℃. While stirring, slowly add a dilute solution of hydrazine hydrate for reduction. Keep the reaction at this temperature for 2.5h. After cooling, centrifuge, wash, and dry to obtain few-layer ternary composite functional powder and multilayer ternary composite functional powder, respectively.

[0052] S4. Mix the few-layer ternary composite functional powder and the multi-layer ternary composite functional powder at a mass ratio of 25:75, add about 0.5g of dispersant (BYK-2150), and disperse at high speed at 9000r / min for 20min to obtain gradient composite powder.

[0053] S5. By weight, take 5 parts of gradient composite powder, 65 parts of acrylic resin, 3 parts of fluorinated modified acrylate hydrophobic additive, 22 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 8 parts of isocyanate curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to fineness ≤30μm, filter and discharge to obtain the finished coating.

[0054] S6. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 60℃ for 2 hours to obtain an anti-corrosion and anti-fouling coating.

[0055] Comparative Example 1 This example provides a method for preparing an anti-corrosion and anti-fouling coating, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, add it to anhydrous ethanol, ultrasonically disperse it at 400W power and 30℃ for 30 min, vacuum dry it at 90℃ for 7 h, grind it through a 400-mesh sieve to obtain pretreated graphene powder.

[0056] S2. By weight, take 5 parts of pretreated graphene powder, 70 parts of epoxy resin, 20 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 7 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0057] S3. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0058] Comparative Example 2 This example provides a method for preparing an anti-corrosion and anti-fouling coating, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, and multi-layer graphene with 6-10 layers and an average particle size of about 5 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0059] S2. Take 10g of pretreated few-layer graphene powder and add it to 500mL of 0.2mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 1.0g of pyrrole monomer. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.3 times that of pyrrole monomer. After the addition is complete, continue the reaction for 5h. The product is separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder.

[0060] S3. The few-layer polypyrrole-coated modified graphene powder obtained in S2 and the untreated multilayer graphene powder are simply mixed at a mass ratio of 25:75. About 0.5g of dispersant (BYK-2150) is added, and the mixture is sheared at 9000r / min for 20min to obtain the mixed powder.

[0061] S4. By weight, take 5 parts of mixed powder, 70 parts of epoxy resin, 20 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 7 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0062] S5. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0063] Comparative Example 3 This example provides a method for preparing an anti-corrosion and anti-fouling coating, the steps of which are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, and multi-layer graphene with 6-10 layers and an average particle size of about 5 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0064] S2. Take 10g of pretreated few-layer graphene powder and 10g of pretreated multilayer graphene powder, respectively, and add them to 500mL of 0.2mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 1.0g of pyrrole monomer to each. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.3 times that of the pyrrole monomer. After the addition is complete, continue the reaction for 5h. The products are separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder and multilayer polypyrrole-coated modified graphene powder, respectively.

[0065] S3. Disperse 8g of the above-mentioned few-layer polypyrrole-coated modified graphene powder and 8g of the above-mentioned multilayer polypyrrole-coated modified graphene powder in 200mL of a mixed solvent of ethanol and water with a volume ratio of 2.5:1. Add 0.24g of silver nitrate and 0.002g of polyvinylpyrrolidone to each, stir evenly, and heat to 50℃. While stirring, slowly add a dilute solution of hydrazine hydrate for reduction. Keep the reaction at this temperature for 2.5h. After cooling, centrifuge, wash, and dry to obtain few-layer ternary composite functional powder and multilayer ternary composite functional powder, respectively.

[0066] S4. Mix the few-layer ternary composite functional powder and the multi-layer ternary composite functional powder at a mass ratio of 25:75, add about 0.5g of dispersant (BYK-2150), and disperse at high speed at 9000r / min for 20min to obtain gradient composite powder.

[0067] S5. By weight, take 5 parts of gradient composite powder, 70 parts of epoxy resin, 20 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 7 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0068] S6. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0069] Comparative Example 4 This example provides a method for preparing an anti-corrosion and anti-fouling coating. The specific steps are as follows: S1. Select few-layer graphene with 1-5 layers and an average particle size of about 1 μm, and multi-layer graphene with 6-10 layers and an average particle size of about 5 μm. Add them to anhydrous ethanol and ultrasonically disperse them at 400W power and 30℃ for 30 min. Then, vacuum dry them at 90℃ for 7 h and grind them through a 400-mesh sieve to obtain two types of graded graphene powders.

[0070] S2. Take 10g of pretreated few-layer graphene powder and 10g of pretreated multilayer graphene powder, respectively, and add them to 500mL of 0.2mol / L hydrochloric acid aqueous solution. After stirring and dispersing evenly, add 1.0g of pyrrole monomer to each. Under ice-water bath (0-5℃) and mechanical stirring at 400r / min, slowly add an aqueous solution containing ammonium persulfate. The molar amount of ammonium persulfate is 1.3 times that of the pyrrole monomer. After the addition is complete, continue the reaction for 5h. The products are separated by centrifugation, washed alternately with deionized water and ethanol until neutral, and dried under vacuum at 80℃ for 6h to obtain few-layer polypyrrole-coated modified graphene powder and multilayer polypyrrole-coated modified graphene powder, respectively.

[0071] S3. Mix the few-layer polypyrrole-coated modified graphene powder and the multi-layer polypyrrole-coated modified graphene powder at a mass ratio of 25:75, add about 0.5g of dispersant (BYK-2150), and disperse at high speed at 9000r / min for 20min to obtain gradient composite powder.

[0072] S4. By weight, take 5 parts of gradient composite powder, 70 parts of epoxy resin, 3 parts of silicone hydrophobic additive, 20 parts of xylene-butyl acetate-ethanol mixed solvent (volume ratio of the three is 5:4:1), 7 parts of curing agent, 0.5 parts of leveling agent (BYK-333) and 0.5 parts of defoamer (BYK-066N), mix them, stir at high speed for 30 minutes, grind them to a fineness of ≤30μm, filter and discharge to obtain the finished coating.

[0073] S5. Apply the coating to the treated steel plate surface by spraying. The dry film thickness is about 25μm. After surface drying at room temperature, cure at 70℃ for 3 hours to obtain an anti-corrosion and anti-fouling coating.

[0074] The coatings prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance testing according to GB / T 1771-2007, GB / T 1732, GB / T 10485, and GB / T 21866. The test results are as follows:

[0075] The following clear conclusions can be drawn from the above test results: 1. Examples 1 to 3 all exhibited excellent comprehensive performance in different resin systems, with a water contact angle ≥115°, salt spray resistance ≥3200h, antibacterial and antifouling rate ≥98%, adhesion grade 0, and porosity ≤0.9%. This indicates that the multi-specification composite graphene modified anti-corrosion and antifouling coating preparation method provided by the present invention has good adaptability to different resin matrices, and its various properties are significantly better than those of traditional graphene coatings.

[0076] 2. Comparative Example 1 uses unmodified single graphene. The coating has a water contact angle of only 62°, rust appears after 1200 hours of salt spray resistance, has no antibacterial ability, has an adhesion grade of 1, and a porosity as high as 3.2%. Compared with Example 1, this fully demonstrates that polypyrrole coating, silver nanoparticle loading, gradient compounding, and hydrophobic modification are the key to achieving high performance.

[0077] 3. Comparative Example 2 only coated few-layer graphene with polypyrrole, without loading silver nanoparticles, without gradient compounding, and without adding hydrophobic additives. Its water contact angle was 75°, and local blistering occurred after 1800 hours of salt spray resistance. It had no antibacterial effect, its adhesion dropped to level 2, and its porosity was 2.1%. The comparison with Example 1 and Comparative Example 3 shows that the lack of silver nanoparticles and biomimetic hydrophobic structure will significantly weaken the antibacterial and antifouling capabilities and hydrophobic self-cleaning performance of the coating.

[0078] 4. Comparative Example 3, based on Example 1, removed the hydrophobic additive, resulting in a sharp drop in water contact angle to 78° and a decrease in salt spray resistance (slight bubbling occurred after 2400 hours). However, the antibacterial and antifouling rates and adhesion remained at a high level. This alone confirms the key role of the hydrophobic additive in constructing biomimetic micro / nano rough hydrophobic surfaces, improving coating hydrophobicity, and extending salt spray resistance life. It also indicates that the gradient compounding of ternary composite functional powders itself endows the coating with excellent antibacterial and compact properties.

[0079] 5. Comparative Example 4, without silver nanoparticle loading, exhibited comparable water contact angle, salt spray resistance, adhesion, and porosity to Example 1, but completely lost its antibacterial and antifouling capabilities, with noticeable microbial adhesion appearing after 72 hours. This demonstrates the decisive role of silver nanoparticles in imparting antibacterial and antifouling functions to the coating, and that the introduction of silver nanoparticles does not negatively impact other core properties of the coating.

[0080] In summary, this invention combines several technical means, including multi-specification graphene gradient compounding, polypyrrole conductive polymer coating, silver nanoparticle loading, and biomimetic micro-nano rough hydrophobic structure, to achieve significant synergistic effects in corrosion prevention, antifouling, hydrophobic self-cleaning, and coating density. All performance characteristics significantly surpass those of traditional and single-modified graphene coatings, meeting the application requirements of harsh marine environments and heavy-duty industrial corrosion protection.

[0081] 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 multi-specification composite graphene-modified anti-corrosion and anti-fouling coating, characterized in that: By weight, its raw materials include: 3-8 parts of gradient composite powder; 60-75 parts of resin matrix; 2-4 parts of hydrophobic additive; Solvent 15-25 parts; 5-10 parts of curing agent; Functional additives 1-3 parts; The gradient composite powder is composed of a few-layer ternary composite powder and a multi-layer ternary composite powder. The mass percentage of the few-layer ternary composite powder is 20%-30%, and the mass percentage of the multi-layer ternary composite powder is 70%-80%. The ternary composite powder includes graphene, a polypyrrole layer coated on the surface of graphene, and silver nanoparticles loaded on the polypyrrole layer.

2. The multi-specification composite graphene-modified anti-corrosion and anti-fouling coating according to claim 1, characterized in that: The graphene in the few-layer ternary composite powder is few-layer graphene with 1-5 layers and a particle size of 0.5-2 μm; the graphene in the multi-layer ternary composite powder is multi-layer graphene with 6-15 layers and a particle size of 3-8 μm.

3. The multi-specification composite graphene-modified anti-corrosion and anti-fouling coating according to claim 1, characterized in that: The resin matrix is ​​any one or more of epoxy resin, polyurethane resin, and acrylic resin; The hydrophobic additive is a fluorinated modified acrylate or an organosilicon hydrophobic additive. The solvent is a xylene-butyl acetate-ethanol mixed solvent; The functional additives include leveling agents, defoamers, and dispersants.

4. A method for preparing a multi-specification composite graphene-modified anti-corrosion and anti-fouling coating according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Select few-layer graphene and multi-layer graphene, pre-treat them respectively, and obtain hierarchical graphene powder; S2: The graded graphene powder is dispersed in an acidic aqueous solution, pyrrole monomer is added, and an oxidant is added under low temperature stirring conditions to initiate an in-situ polymerization reaction. The reaction product is centrifuged, washed, and dried to obtain polypyrrole-coated modified graphene powder. S3: The polypyrrole-coated modified graphene powder is dispersed in an ethanol-water mixed solvent, a silver salt precursor and a stabilizer are added, and silver nanoparticles are loaded in situ on the surface of the polypyrrole coating through a reduction reaction to obtain a ternary composite functional powder. S4: The ternary composite functional powder corresponding to few-layer graphene and the ternary composite functional powder corresponding to multi-layer graphene are compounded and mixed in proportion, and dispersed by high-speed shearing to obtain gradient composite powder. S5: The gradient composite powder, resin matrix, hydrophobic additive, solvent, curing agent and functional additive are mixed, and then stirred, milled and filtered to obtain the multi-specification composite graphene modified anti-corrosion and anti-fouling coating.

5. The preparation method according to claim 4, characterized in that: In S1, the pretreatment method is as follows: add anhydrous ethanol and ultrasonically disperse for 20-40 min, ultrasonic power 300-500W, dispersion temperature 25-35℃, then vacuum dry at 80-100℃ for 6-8 h, and grind through a 300-500 mesh sieve.

6. The preparation method according to claim 4, characterized in that: In S2, the acidic aqueous solution is a hydrochloric acid solution with a concentration of 0.1-0.3 mol / L; the oxidant is ammonium persulfate. The solid-liquid ratio of the graded graphene powder to the acidic aqueous solution is 1:(40-60)g / mL; The mass ratio of the graded graphene powder to the pyrrole monomer is (10-15):1; The molar ratio of the oxidant to the pyrrole monomer is (1.2-1.5):1; The in-situ polymerization reaction is carried out at a temperature of 0-5℃, a stirring speed of 300-500 r / min, and a reaction time of 4-6 h.

7. The preparation method according to claim 4, characterized in that: In S3, the volume ratio of ethanol to deionized water in the ethanol-water mixed solvent is (2-3):1; The silver salt precursor is silver nitrate, and its addition amount is 2%-5% of the mass of polypyrrole-coated modified graphene powder; The stabilizer is polyvinylpyrrolidone, and the amount added is 0.5%-1% of the mass of the silver salt precursor; The reduction reaction uses hydrazine hydrate as the reducing agent, with a reduction temperature of 40-60℃, a reaction time of 2-3 hours, and a stirring speed of 400-600 r / min.

8. The preparation method according to claim 4, characterized in that: In step S4, after compounding, a dispersant is added, and the high-speed shear dispersion is performed at a speed of 8000-10000 r / min for 15-25 min.

9. The preparation method according to claim 4, characterized in that: Step S5 is followed by S6 construction and curing: the obtained multi-specification composite graphene modified anti-corrosion and anti-fouling coating is sprayed or brushed onto the substrate surface, with a single coating thickness of 20-30μm. After surface drying at room temperature, it is cured at a constant temperature of 60-80℃ for 2-4 hours to form a coating. The coating has a biomimetic micro-nano rough hydrophobic surface with a water contact angle ≥115°.

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