Marine anticorrosive coating containing graphene-based adjuvant and preparation method thereof

Abstract

The application belongs to the field of functional coating, and particularly relates to a marine anticorrosive coating containing a graphene-based additive and a preparation method thereof. The marine anticorrosive coating containing the graphene-based additive is a two-component coating, wherein the A component includes the graphene-based additive, which is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide coated graphene, and contains a conductive graphene core layer, a first shell layer of nitrogen-doped titanium oxide and a second shell layer of polyphenol surface coating. A metal ion crosslinking agent solution is further added to the coating before construction, so that the graphene-based additive is in-situ coordination crosslinked. The marine anticorrosive coating containing the graphene-based additive solves the problem of accelerated corrosion caused by electrochemical corrosion when graphene is used as an anticorrosive filler in the prior art through molecular structure design and formula design.

Description

Technical Field

[0001] This invention belongs to the field of functional coatings, specifically relating to a marine anti-corrosion coating containing graphene-based additives and its preparation method. Background Technology

[0002] Existing marine anti-corrosion coatings are widely used in ships, offshore platforms, and port steel structures. They typically use epoxy, polyurethane, or other resins as film-forming agents, and add glass flakes and other sheet-like fillers to create a "labyrinth effect" to reduce the corrosion caused by water, oxygen, and chloride ions. - The penetration rate is high. However, under conditions such as long-term immersion, alternating wet and dry conditions in the splash zone, and mechanical impact, the coating is still prone to microcracks or interface debonding. After electrolytes enter, they cause pitting corrosion propagation, blistering, and scratch spread. At the same time, marine biofouling forms a biofilm on the surface, changing the local oxygen concentration gradient and ion transport conditions, further promoting localized corrosion and coating failure. Therefore, how to achieve high shielding, strong adhesion, resistance to damp heat, and antifouling in a few-layer system is a significant technical challenge for marine anti-corrosion materials.

[0003] To enhance barrier and mechanical properties, existing technologies often incorporate conductive carbon materials (such as graphene) as functional fillers. The sheet-like structure of graphene can significantly extend the diffusion path of corrosive media and improve coating density to some extent; however, its high conductivity can lead to electrochemical side effects in the presence of salt electrolytes. When graphene forms electrical contact with the metal substrate or forms a continuous conductive network within the coating, graphene tends to act as a relatively inert cathode phase, promoting cathodic reactions such as oxygen reduction, leading to accelerated anodic dissolution of the metal substrate—the so-called galvanic effect and "cathodic acceleration." Electrochemical activity is particularly high at defects and edge sites of the graphene sheets, making them more prone to becoming cathodic reaction hotspots. Once water seeps into the coating, the increased local current density exacerbates pitting corrosion initiation and propagation. On the other hand, if the dispersion of graphene in the coating is unstable, agglomerates can form pores and defect channels, weakening the shielding effect. This creates an inherent contradiction between "enhanced sheet shielding" and "increased risk of electrochemical corrosion," making it difficult to consistently achieve long-term corrosion protection benefits simply by adding graphene.

[0004] To address the aforementioned contradictions, existing technologies typically employ two approaches: one is to encapsulate graphene with insulating or semiconductor coatings (such as...). One approach is to reduce the risk of galvanic corrosion by coating with particles / sol. Another approach is to introduce corrosion inhibitors, coupling agents, or reactive compatibilizers to improve the bonding between the filler / resin / metal interface and form a protective film at defects. However, these approaches often bring new drawbacks: while insulating coating reduces the risk of galvanic corrosion, it significantly weakens the electron transport capacity of graphene, making it difficult for it to play a positive role in the regulation of interface potential distribution and electron migration. In marine corrosion protection practice, maintaining a certain level of conductivity often helps to reduce local potential difference and peak current density, and alleviate pitting corrosion driving forces. Inorganic particle coating may also introduce dispersion difficulties and increased porosity, reducing the density of the coating; small molecule corrosion inhibitors / compensators are prone to migration and loss, and the interface protection weakens after long-term immersion; if reactive systems react prematurely during the mixing or film-forming stage, it can easily lead to a shortened pot life, thickening and flocculation, and a narrowed construction window, affecting engineering scale-up and quality stability.

[0005] Therefore, a new composite structure and preparation strategy is urgently needed: while maintaining the labyrinth effect of sheet-like fillers and the advantages of controllable electron transport of conductive materials, it should suppress galvanic corrosion and simultaneously possess antifouling properties, thereby meeting the comprehensive requirements of long-term corrosion protection, antifouling, and construction adaptability in marine environments. Summary of the Invention

[0006] The purpose of this invention is to address the problem of accelerated corrosion caused by electrochemical corrosion when graphene is used as an anti-corrosion filler in existing marine anti-corrosion coatings. This invention provides a marine anti-corrosion coating with graphene-based additives and its preparation method. Through molecular structure design, graphene is encapsulated in a double-shell structure, ensuring conductivity while preventing electrochemical corrosion. Through formulation design, a metal ion crosslinking agent is introduced to provide high crosslinking density and self-healing properties. Furthermore, the corrosion resistance is further improved through a synergistic resin system. To achieve the above objectives, the technical solution adopted by this invention to solve its technical problems is as follows: This invention provides a marine anti-corrosion coating containing graphene-based additives, which is a two-component coating comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 0.5-2.0 parts of graphene-based additives; Zinc oxide 1.0-3.0 parts; 5.0-10.0 parts of sheet-like shielding filler; 5.0-10.0 parts of inert filler; Dispersant 1.0-2.0 parts; Defoamer 0.1-0.3 parts; Leveling agent 0.5-1.0 parts; 5-20 parts deionized water; Component B: 15-30 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

[0007] Furthermore, The film-forming resin is a mixture of aqueous hydroxyl acrylic resin and epoxy emulsion in a weight ratio of 2-4 / 1; and The aqueous hydroxyl acrylic resin has a solid content of 40-50% and a hydroxyl content (based on solids) of 2.0-2.5%; the epoxy emulsion has a solid content of 40-50%.

[0008] Furthermore, The graphene-based additive includes the following preparation steps: S11, graphene, titanium source and nitrogen source are subjected to hydrolysis-deposition reaction to obtain nitrogen-doped titanium oxide-coated graphene precursor; S12, the product of S11 is nitrided to obtain nitrogen-doped titanium oxide-coated graphene; S13 involves placing the product of S12 into a polyphenol solution for a self-assembly reaction to obtain a double-shell core-shell structure of polyphenol / nitrogen-doped titanium dioxide-coated graphene, which is the target product.

[0009] Furthermore, The ratio of graphene, titanium source, and nitrogen source used is 1g:0.5-2.0g:0.2-3.0g; and The graphene is rGO; The titanium source is tetraisopropyl titanate, titanium isopropoxide, or tetrabutyl titanate. The nitrogen source is urea or melamine.

[0010] Furthermore, The nitriding treatment is carried out in a nitrogen or nitrogen / ammonia mixed environment at 400-500℃ for 1.0-3.0h.

[0011] Furthermore, The concentration of the polyphenol solution is 0.5-2.0 g / L; and The polyphenols are tannic acid, gallic acid, or catechin.

[0012] Furthermore, The particle size of the zinc oxide is ;as well as The sheet-like shielding filler is selected from one or more of glass flakes, mica powder, and sheet-like silicates to synergistically form a multi-scale labyrinth effect with the graphene sheets.

[0013] Furthermore, The metal ion crosslinking agent includes Crosslinking agent and / or Crosslinking agent; and The The amount of crosslinking agent used is 0.1-0.3 wt% of the total solids. The The amount of crosslinking agent used is 0.05-0.15 wt% of the total solids.

[0014] Another object of the present invention is to provide a method for preparing component A of the above-mentioned marine anti-corrosion coating, comprising the following steps: S21: Add film-forming resin, zinc oxide, sheet-like shielding filler, inert filler, dispersant, defoamer, leveling agent and some deionized water to the reaction vessel, stir at low speed to mix evenly, and then stir at high speed for 2-3 hours to obtain slurry; S22: Add graphene-based additives and remaining deionized water; stir at low speed for 0.5 h, then ultrasonically disperse for 30 min to obtain a dispersion; S23: Add the dispersion from S22 to the mixed solution from S21, stir until homogeneous, and obtain component A.

[0015] Another object of the present invention is to provide a coating prepared by the above-mentioned marine anti-corrosion coating, which is a single-layer coating and is suitable for marine steel structures, ships, offshore platforms and port facilities.

[0016] The present invention has the following beneficial effects: (1) This invention provides a marine anti-corrosion coating containing graphene-based additives, which uses double-shell coated graphene as an anti-corrosion filler to reduce the risk of galvanic corrosion and cathodic acceleration in seawater environment; and adds metal ion crosslinking agent before construction to further "lock" the graphene-based additives with the main resin network, improve the interface adhesion durability and the self-healing property of the dynamic coordination network, and effectively improve the anti-corrosion performance.

[0017] (2) This invention provides a marine anti-corrosion coating containing graphene-based additives. Through formulation design, graphene sheets and sheet-like fillers such as glass flakes / mica synergistically construct a multi-scale labyrinth diffusion path, significantly extending the water / oxygen diffusion range. Migration path; combined with complexation densification and zinc oxide filling effect, high shielding and long-term stability of single-layer thick film are achieved.

[0018] (3) This invention provides a marine anti-corrosion coating containing graphene-based additives. The nitrogen-doped titanium dioxide first shell provides a stable surface and controllable photochemical antifouling potential, while the polyphenol-coated second shell reduces fouling adhesion. Zinc oxide is released slowly in seawater. It inhibits the initial attachment of bacteria / algae and the formation of biofilm; the water-based 2K system has low VOC and better construction safety, making it suitable for on-site coating in marine engineering projects.

[0019] In summary, the marine anti-corrosion coating containing graphene-based additives provided by this invention, through molecular structure and formulation design, achieves synergistic effects from three perspectives: physical barrier corrosion prevention, cathodic protection corrosion prevention, and self-healing, resulting in highly efficient anti-corrosion and anti-fouling performance. Simultaneously, it enhances anti-fouling performance from two levels: photochemical anti-fouling and zinc oxide slow-release inhibition of algae adhesion. It has broad application prospects. Detailed Implementation

[0020] The present invention will be described in detail below with reference to the embodiments. However, it should be understood that the following embodiments are merely illustrative examples of the implementation of the present invention and are not intended to limit the scope of the present invention. Furthermore, unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer, and the raw materials used in the following embodiments are all commercially available.

[0021] The purpose of this invention is to develop a marine anti-corrosion coating containing graphene-based additives. The approach is as follows: addressing the problem of accelerated corrosion caused by electrochemical corrosion when using graphene as an anti-corrosion filler in existing marine anti-corrosion coatings, this invention focuses on the structural design and interfacial chemical enhancement of functional fillers to prepare a graphene-based composite additive with both high shielding and high interfacial stability. This additive synergistically enhances anti-corrosion and antifouling performance with a zinc source and sheet-like fillers. The theoretical basis is as follows: using reduced graphene oxide as the core, a titanium oxide precursor thin layer is formed by controlled deposition of titanium and nitrogen sources. This is followed by low-temperature nitriding to obtain a nitrogen-doped titanium oxide shell, stabilizing and passivating the sheet surface while maintaining its shielding advantages. Subsequently, a polyphenol structure is coated onto the surface to form a polyphenol layer. Before application, zinc or zirconium salts are added as crosslinking agents, allowing the polyphenols to coordinate and crosslink in situ during film formation, enhancing the interfacial bonding between the composite additive and the resin / substrate. Re-complexation occurs at damaged or water-permeable areas, improving durability and self-healing performance. In this water-based two-component system, the components work synergistically to achieve a comprehensive improvement in low permeability, high adhesion, and antifouling properties while maintaining workability and mechanical properties. An embodiment of this invention is as follows: This invention provides a marine anti-corrosion coating containing graphene-based additives, which is a two-component coating comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 0.5-2.0 parts of graphene-based additives; Zinc oxide 1.0-3.0 parts; 5.0-10.0 parts of sheet-like shielding filler; 5.0-10.0 parts of inert filler; Dispersant 1.0-2.0 parts; Defoamer 0.1-0.3 parts; Leveling agent 0.5-1.0 parts; 5-20 parts deionized water; Component B: 15-30 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

[0022] The film-forming resin is a mixture of water-based hydroxyl acrylic resin and epoxy emulsion in a weight ratio of 2-4 / 1. The waterborne hydroxyl acrylic resin has a solid content of 40-50% and a hydroxyl content (based on solids) of 2.0-2.5%; furthermore, the waterborne hydroxyl acrylic resin described in this invention and the following embodiments is... (45±2% solids content, 2.2% hydroxyl content (based on solids)) purchased from Wuxi Honghui New Material Technology Co., Ltd.

[0023] The epoxy emulsion has a solid content of 40-50%; and the aqueous hydroxyl acrylic resin used in this invention and the following embodiments is... (40±2% solids content), purchased from Wuxi Honghui New Material Technology Co., Ltd.

[0024] The graphene-based additive includes the following preparation steps: S11, graphene was added to a mixed solvent of anhydrous ethanol / deionized water (V / V=9 / 1) and ultrasonically dispersed for 30 min; then, the mixture was stirred at a low speed of 500 r / min, the pH was adjusted to 3.5, and an ethanol solution of titanium source (concentration 10wt%) was added dropwise. After the addition was completed, stirring was continued for 3 h; a nitrogen source was added, and stirring was continued for 30 min; the mixture was allowed to stand, filtered, and the filter residue was washed with anhydrous ethanol; the solid was placed at 60 °C and vacuum dried for 10 h to obtain the precursor of nitrogen-doped titanium oxide coated graphene.

[0025] The ratio of graphene, mixed solvent, titanium source, and nitrogen source is 1g:200mL:0.5-2.0g:0.2-3.0g; and The graphene is rGO; The titanium source is tetraisopropyl titanate, titanium isopropoxide, or tetrabutyl titanate. The nitrogen source is urea or melamine.

[0026] S12: The S11 product is evenly spread in a ceramic boat, placed in a tube furnace, and a nitrogen or nitrogen / ammonia mixture (V / V=95 / 5) atmosphere is introduced and kept at 400-500℃ for 1.0-3.0h. After the heat treatment, the furnace is cooled to room temperature to obtain nitrogen-doped titanium oxide-coated graphene.

[0027] The nitrogen or mixed gas flow rate is 300 mL / min; The heating rate is 3℃ / min.

[0028] S13: Place the product of S12 in a polyphenol solution, stir at 20-35℃ for 1.0-2.0h, let stand, filter, take the filter residue, and rinse with deionized water; place the solid at 60℃ and vacuum dry for 10h to obtain a polyphenol / nitrogen-doped titanium dioxide-coated graphene double-shell core-shell structure, i.e., the target product.

[0029] The ratio of the S12 product to the polyphenol solution is 1g:300mL; The polyphenol solution concentration is 0.5-2.0 g / L, and the solvent is deionized water; and The polyphenols are tannic acid, gallic acid, or catechin.

[0030] The particle size of the zinc oxide is Furthermore, the zinc oxide described in this invention and the following embodiments is ML-ZnO-300 (average particle size 300nm), purchased from Zhejiang Manli Nanotechnology Co., Ltd.

[0031] The sheet-like shielding filler is selected from one or more of glass flakes, mica powder, and sheet-like silicates to synergistically form a multi-scale labyrinth effect with the graphene sheets.

[0032] The glass flakes have a thickness of Particle size Purchased from Japanese sheet glass.

[0033] The mica powder, specification HY-M1, was purchased from Shenzhen Haiyang Powder Technology Co., Ltd.

[0034] The sheet silicate, model P-5540, was purchased from BYK.

[0035] The inert filler is precipitated barium sulfate, talc, or kaolin. Furthermore, in the following embodiments of the present invention, the inert filler is a mixture of precipitated barium sulfate and kaolin added at a mass ratio of 3:2.

[0036] The dispersant is BYK-2080.

[0037] The defoamer is BYK-022.

[0038] The leveling agent is Tego 440.

[0039] The water-based isocyanate curing agent is OS-9018.

[0040] The metal ion crosslinking agent includes Crosslinking agent and / or Crosslinking agent; and The The crosslinking agent can be zinc acetate, zinc lactate, zinc citrate, etc.; the amount used is 0.1-0.3 wt% of the total solids. The The crosslinking agent can be zirconium acetylacetonate, and the amount used is 0.05-0.15 wt% of the total solids.

[0041] The solvent for the metal ion crosslinking agent solution is deionized water with a concentration of 5 wt%.

[0042] The graphene-based additive prepared in this invention has a double-shell structure: a first continuous shell layer is prepared by chemical deposition (the shell thickness can be adjusted by dosage); the first shell layer is stabilized and further densified and made conductive by nitriding; a second shell layer is formed by self-assembly reaction with polyphenols, and can be used for subsequent reactions with polyphenols. Dynamic cross-linking is carried out.

[0043] The protective mechanism of this invention's water-based two-component anti-corrosion and anti-fouling coating can be summarized as a synergistic process of "shielding-controlling coupling-complexing cross-linking-densification-self-healing": First, graphene sheets and sheet-like fillers such as glass flakes / mica construct a multi-scale "maze effect" in the coating, significantly prolonging the protection of water, oxygen, and Cl-. - The coating's intrinsic shielding and corrosion-resistant capabilities are achieved by firstly blocking the diffusion path of corrosive media and reducing the penetration rate; secondly, the nitrogen-doped titanium oxide first shell on the graphene sheet surface, while maintaining controllable electron transport channels, passivates highly active sites such as graphene defects / edges, suppressing electrochemical side effects such as galvanic corrosion and cathodic acceleration, achieving a synergistic effect of "maintaining conductivity and controlling galvanic corrosion"; thirdly, the second shell polyphenol can form a multi-site complex adsorption film on the first shell and the metal substrate surface, which is added before construction. The crosslinking agent enables the in-situ formation of a coordination crosslinking network, significantly improving the interfacial bonding strength and crosslinking density between the composite functional filler and its components, and reducing the risk of interfacial debonding and micropore permeation; simultaneously, ZnO acts as... The slow-release source and functional filler promote the formation of complex protective phases at interfaces and defects, and fill and densify the coating microstructure, thereby improving adhesion retention and long-term durability in seawater environments; Fourth. The coordination network has dynamic and reversible recombination / recrosslinking characteristics. When microcracks or scratches occur in the coating and moisture enters, the complex film can be reconstructed at the defect interface and the permeation channels can be blocked, demonstrating self-repair and anti-scratch propagation effects. In addition, the polyphenol layer can improve the dispersion and wetting of composite functional fillers in water-based resins. Moreover, the polyphenol layer can undergo reversible adsorption and coordination exchange under seawater / humid heat conditions to achieve dynamic reconstruction of the interface layer: on the one hand, it continuously blocks and inhibits corrosion at the defect, and on the other hand, it avoids excessive insulation to maintain the controllable electron transport capability of the first shell layer and the conductive network, thereby taking into account both the electron transport required for cathodic protection and long-term corrosion resistance.

[0044] Meanwhile, its antifouling mechanism is as follows: First, the nitrogen-doped titanium dioxide first shell has stable surface chemical properties and photochemical activity, which can photocatalytically decompose organic fouling under light conditions and reduce the initial adhesion of fouling to the coating surface; Second, the polyphenol layer can reduce the surface adhesion sites, interfere with the initial formation of biofilm, and interact with... The cross-linked network collectively constructs a more stable interface layer, thereby improving antifouling durability; third, the ZnO and its released... It has a certain inhibitory effect on microorganisms, which can reduce the risk of biofilm and microbial corrosion and synergistically improve the ability to resist biofouling; fourth, the high shielding and self-healing anti-corrosion mechanism ensures the long-term integrity of the paint film and low defect rate, reduces the "anchoring effect" of corrosion products and rough defects on attached organisms, thereby indirectly improving the antifouling effect and stability.

[0045] This graphene-based additive and coating system exhibit significant synergistic effects in corrosion prevention and antifouling: shielding and interface densification reduce the entry of corrosive media, while galvanocoupler control and coordination self-healing stabilize the electrochemical environment and maintain the integrity of the coating film, thereby reducing fouling adhesion and biocorrosion induction factors; the antifouling mechanism further reduces biofilm formation and local microenvironment acidification / enrichment. The two factors, such as the promoting effect on corrosion, complement each other, improving the overall anti-corrosion and anti-fouling performance of the coating and expanding its application prospects in marine engineering.

[0046] Another objective of this invention is to provide a method for preparing component A of the above-mentioned marine anti-corrosion coating, comprising the following steps: S21: Add film-forming resin, zinc oxide, sheet-like shielding filler, inert filler, dispersant, defoamer, leveling agent and part of deionized water to the reaction vessel, stir at low speed (500 r / min) to mix evenly, and then stir at high speed (2000 r / min) for 2-3 hours to obtain slurry; S22: Add graphene-based additives and remaining deionized water; stir at low speed (500 r / min) for 0.5 h, then ultrasonically disperse for 30 min to obtain a dispersion; S23: Add the dispersion from S22 to the mixed solution from S21, stir (500 r / min) until homogeneous, and obtain component A.

[0047] Another object of the present invention is to provide a coating prepared by the above-mentioned marine anti-corrosion coating, which is a single-layer coating and is suitable for marine steel structures, ships, offshore platforms and port facilities.

[0048] To further understand the present invention, the following detailed description, in conjunction with embodiments, provides a marine anti-corrosion coating containing graphene-based additives and its preparation method. The scope of protection of the present invention is not limited by the following embodiments. Example 1

[0049] A marine anti-corrosion coating containing graphene-based additives is a two-component coating comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 1.2 parts of graphene-based additives; 2.0 parts zinc oxide; 7.5 parts of sheet-like shielding filler; 8.0 parts of inert filler; 1.5 parts dispersant; 0.2 parts of defoamer; 0.8 parts leveling agent; 10 parts deionized water; Component B: 24 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

[0050] The film-forming resin is a mixture of waterborne hydroxy acrylic resin and epoxy emulsion in a weight ratio of 3 / 1.

[0051] The graphene-based additive includes the following preparation steps: S11, rGO was added to a mixed solvent of anhydrous ethanol / deionized water (V / V=9 / 1) and ultrasonically dispersed for 30 min; then, the mixture was stirred at a low speed of 500 r / min, the pH was adjusted to 3.5, and an ethanol solution of tetrabutyl titanate (concentration 10wt%) was added dropwise. After the addition was completed, stirring was continued for 3 h; urea was added, and stirring was continued for 30 min; the mixture was allowed to stand, filtered, and the filter residue was washed with anhydrous ethanol; the solid was placed at 60 °C and vacuum dried for 10 h to obtain the precursor of nitrogen-doped titanium dioxide coated graphene.

[0052] The ratio of rGO, mixed solvent, tetrabutyl titanate, and urea is 1g:200mL:1.0g:1.5g.

[0053] Its reflected infrared data is as follows: -NH- exists; -C=O exists; -CN exists; Ti-O is present.

[0054] S12: The S11 product was evenly spread in a ceramic boat, placed in a tube furnace, and a nitrogen / ammonia mixed atmosphere (V / V=95 / 5) was introduced. The furnace was kept at 450℃ for 1.5h. After the heat treatment, the furnace was cooled to room temperature to obtain nitrogen-doped titanium oxide-coated graphene.

[0055] Its reflected infrared data is as follows: -NH- does not exist; -C=O does not exist; :-CN does not exist; Ti-O is present; Ti-N exists.

[0056] Elemental analysis showed that the nitrogen content was 1.8 wt%.

[0057] S13: The product of S12 was placed in a tannic acid solution, stirred at 30°C for 1.5 h, allowed to stand, filtered, and the filter residue was washed with deionized water. The solid was then vacuum dried at 60°C for 10 h to obtain a tannic acid / nitrogen-doped titanium dioxide-coated graphene double-shell core-shell structure, which is the target product.

[0058] The ratio of the S12 product to the tannic acid solution is 1g:300mL; The concentration of the tannic acid solution is 1.0 g / L.

[0059] Its reflected infrared data is as follows: -OH is present; , : Benzene ring is present; -C=O exists.

[0060] The sheet-like shielding filler is made by adding glass flakes and mica powder at a mass ratio of 2:1.

[0061] The metal ion crosslinking agent is zinc acetate, and the amount used is 0.2 wt% of the total solids. Example 2

[0062] A marine anti-corrosion coating containing graphene-based additives is a two-component coating comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 0.5 parts of graphene-based additive; 3.0 parts zinc oxide; 10.0 parts of sheet-like shielding filler; 5.0 parts of inert filler; 1.0 part of dispersant; 0.1 parts of defoamer; 0.5 parts leveling agent; 20 parts deionized water; Component B: 30 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

[0063] The film-forming resin is a mixture of waterborne hydroxy acrylic resin and epoxy emulsion in a weight ratio of 4 / 1.

[0064] The graphene-based additive includes the following preparation steps: S11, rGO was added to a mixed solvent of anhydrous ethanol / deionized water (V / V=9 / 1) and ultrasonically dispersed for 30 min; then, the mixture was stirred at a low speed of 500 r / min, the pH was adjusted to 3.5, and an ethanol solution of tetraisopropyl titanate (concentration 10wt%) was added dropwise. After the addition was completed, stirring was continued for 3 h; urea was added, and stirring was continued for 30 min; the mixture was allowed to stand, filtered, and the filter residue was washed with anhydrous ethanol; the solid was placed at 60 °C and vacuum dried for 10 h to obtain the precursor of nitrogen-doped titanium dioxide coated graphene.

[0065] The ratio of rGO, mixed solvent, tetraisopropyl titanate, and urea is 1g:200mL:0.5g:3.0g.

[0066] S12: The S11 product was evenly spread in a ceramic boat, placed in a tube furnace, and a nitrogen / ammonia mixed atmosphere (V / V=95 / 5) was introduced. The furnace was kept at 400℃ for 2.0h. After the heat treatment, the furnace was cooled to room temperature to obtain nitrogen-doped titanium oxide-coated graphene.

[0067] S13: The product of S12 was placed in gallic acid solution, stirred at 20°C for 2.0 h, allowed to stand, filtered, and the filter residue was washed with deionized water. The solid was then vacuum dried at 60°C for 10 h to obtain a gallic acid / nitrogen-doped titanium dioxide-coated graphene double-shell core-shell structure, which is the target product.

[0068] The ratio of the S12 product to the gallic acid solution is 1g:300mL; The concentration of the gallic acid solution is 2.0 g / L.

[0069] The sheet-like shielding filler is made by adding glass flakes and sheet-like silicates at a mass ratio of 2:1.

[0070] The metal ion crosslinking agent is zinc acetate, and the amount used is 0.1 wt% of the total solids. Example 3

[0071] A marine anti-corrosion coating containing graphene-based additives is a two-component coating comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 2.0 parts of graphene-based additives; 1.0 part zinc oxide; 5.0 parts of sheet-like shielding filler; 10.0 parts of inert filler; 2.0 parts of dispersant; 0.3 parts of defoamer; Leveling agent 1.0 part; 5.0 parts of deionized water; Component B: 15 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

[0072] The film-forming resin is a mixture of waterborne hydroxy acrylic resin and epoxy emulsion in a weight ratio of 2 / 1.

[0073] The graphene-based additive includes the following preparation steps: S11, rGO was added to a mixed solvent of anhydrous ethanol / deionized water (V / V=9 / 1) and ultrasonically dispersed for 30 min; then, the mixture was stirred at a low speed of 500 r / min, the pH was adjusted to 3.5, and an ethanol solution of titanium isopropoxide (concentration 10wt%) was added dropwise. After the addition was completed, stirring was continued for 3 h; melamine was added, and stirring was continued for 30 min; the mixture was allowed to stand, filtered, and the filter residue was washed with anhydrous ethanol; the solid was placed at 60 °C and vacuum dried for 10 h to obtain the precursor of nitrogen-doped titanium oxide coated graphene.

[0074] The ratio of rGO, mixed solvent, titanium isopropoxide, and melamine used is 1g:200mL:2.0g:0.2g.

[0075] S12: The S11 product was evenly spread in a ceramic boat, placed in a tube furnace, and a nitrogen / ammonia mixed atmosphere (V / V=95 / 5) was introduced. The furnace was kept at 500℃ for 1.0 h. After the heat treatment, the furnace was cooled to room temperature to obtain nitrogen-doped titanium oxide-coated graphene.

[0076] S13: The product of S12 was placed in a catechin solution, stirred at 35°C for 1.0 h, allowed to stand, filtered, and the residue was washed with deionized water. The solid was then vacuum dried at 60°C for 10 h to obtain a double-shell core-shell structure of catechin / nitrogen-doped titanium dioxide-coated graphene, which is the target product.

[0077] The ratio of the S12 product to the catechin solution is 1g:300mL; The concentration of the catechin solution is 0.5 g / L.

[0078] The sheet-like shielding filler is glass flakes.

[0079] The metal ion crosslinking agent is zinc acetate, and the amount used is 0.3 wt% of the total solids. Example 4

[0080] Everything else is the same as in Example 1, except that: The amount of graphene-based additive added is 0.5 parts by weight. Example 5

[0081] Everything else is the same as in Example 1, except that: The amount of the graphene-based additive added is 2.0 parts by weight. Example 6

[0082] Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is zirconium acetylacetonate, and the amount used is 0.1 wt% of the total solids. Example 7

[0083] Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is zirconium acetylacetonate, and the amount used is 0.05 wt% of the total solids. Example 8

[0084] Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is zirconium acetylacetonate, and the amount used is 0.15 wt% of the total solids.

[0085] The following comparative examples are all compared with specific Example 1: Comparative Example 1 Everything else is the same as in Example 1, except that: No graphene-based additives were added to component A.

[0086] Comparative Example 2 Everything else is the same as in Example 1, except that: The graphene-based additive in component A is replaced with rGO.

[0087] Implement Comparative Example 3 Everything else is the same as in Example 1, except that: In step S13 of the preparation of the graphene-based additive, the concentration of tannic acid solution is 0 g / L; that is, no polyphenol surface coating is performed.

[0088] Comparative Example 4 Everything else is the same as in Example 1, except that: In step S13 of the preparation of the graphene-based additive, the concentration of the tannic acid solution is 2.5 g / L.

[0089] Comparative Example 5 Everything else is the same as in Example 1, except that: The preparation steps of the graphene-based additive did not involve S12 nitriding treatment.

[0090] Comparative Example 6 Everything else is the same as in Example 1, except that: In step S11 of the preparation of the graphene-based additive, the ratio of rGO, mixed solvent, tetrabutyl titanate, and urea is 1g:200mL:1.0g:0g.

[0091] Comparative Example 7 Everything else is the same as in Example 1, except that: In step S11 of the preparation of the graphene-based additive, the ratio of rGO, mixed solvent, tetrabutyl titanate, and urea is 1g:200mL:1.0g:4.0g.

[0092] Implemented Comparative Example 8 Everything else is the same as in Example 1, except that: In step S11 of the preparation of the graphene-based additive, the ratio of rGO, mixed solvent, tetrabutyl titanate, and urea is 1g:200mL:0.2g:1.5g.

[0093] Comparative Example 9 Everything else is the same as in Example 1, except that: In step S11 of the preparation of the graphene-based additive, the ratio of rGO, mixed solvent, tetrabutyl titanate, and urea is 1g:200mL:2.5g:1.5g.

[0094] Implement Comparative Example 10 Everything else is the same as in Example 1, except that: In step S11 of the preparation of the graphene-based additive, rGO is replaced with GO.

[0095] Comparative Example 11 Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is zinc acetate, and the amount used is 0 wt% of the total solids; that is, no metal ion crosslinking agent solution was added before construction.

[0096] Comparative Example 12 Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is zinc acetate, and the amount used is 0.4 wt% of the total solids.

[0097] Comparative Example 13 Everything else is the same as in Example 1, except that: The metal ion crosslinking agent is calcium acetate.

[0098] Comparative Example 14 Everything else is the same as in Example 1, except that: No zinc oxide was added to component A.

[0099] Comparative Example 15 Everything else is the same as in Example 1, except that: No sheet-like shielding filler was added to component A.

[0100] Comparative Example 16 Everything else is the same as in Example 1, except that: The film-forming resin in component A does not contain epoxy emulsion.

[0101] Component A prepared in the above examples and comparative examples was added to component B, and after continuous stirring until homogeneous, a metal ion crosslinking agent solution was added and mixed thoroughly. The coating was then applied to tinplate within the activation period, with a dry film thickness of [missing information]. After curing at room temperature for 48 hours, a marine anti-corrosion and anti-fouling coating is obtained.

[0102] The physical properties of the marine anti-corrosion and antifouling coatings prepared in the embodiments and comparative examples of the present invention were measured respectively, and the results are shown in Table 1.

[0103] Table 1 Physical test performance of each embodiment First, compared with Comparative Examples 1-16, the marine anti-corrosion coating containing graphene-based additives of the present invention has excellent physical properties, especially excellent anti-corrosion and biofouling resistance.

[0104] Secondly, as can be observed from Examples 1 and Comparative Examples 1-2, the graphene-based additive in the marine anti-corrosion coating of the present invention has a decisive significance for anti-corrosion and anti-fouling properties; and can effectively solve the electrochemical corrosion problem of graphene. As can be observed from Examples 1 and Comparative Examples 3-5, the double-shell structure of the graphene-based additive, the thickness of the second shell, and the nitriding process of the first shell have a significant impact on achieving cathodic protection against corrosion. As can be observed from Examples 1 and Comparative Examples 6-9, the nitrogen doping and coating thickness of the first shell both have a certain impact on anti-corrosion and anti-fouling properties. This may be because both the first shell and nitrogen doping affect the conductivity of the graphene-based additive, thus affecting the cathodic protection effect; simultaneously, the shell thickness also affects the photocatalytic anti-fouling activity. As can be observed from Examples 1 and Comparative Example 10, reduced graphene oxide has better conductivity and superior anti-corrosion properties compared to graphene oxide. As can be observed from Examples 1 and Comparative Examples 11-13, the coating exhibits better density and dynamic self-healing properties after metal ion crosslinking, effectively improving corrosion and fouling resistance. As can be observed from Examples 1 and Comparative Examples 14-16, zinc oxide has a synergistic effect in corrosion and fouling resistance; the sheet-like shielding filler has synergistic physical barrier corrosion-resistant properties; and the epoxy emulsion contributes to both corrosion resistance and adhesion.

[0105] In summary, the marine anti-corrosion coating containing graphene-based additives of the present invention works synergistically from the perspectives of physical barrier corrosion prevention, cathodic protection corrosion prevention, and self-repair, and has a multi-level effect from photochemical antifouling and zinc oxide slow-release inhibition of algae adhesion, significantly improving anti-corrosion performance and biofouling resistance.

[0106] The testing method is as follows: (1) Adhesion: Adhesion test shall be performed in accordance with the method described in GB / T 9286-2021.

[0107] (2) Impact resistance: Tested according to the method described in GB / T 1732-2020.

[0108] (3) Resistance to neutral salt spray: Tested according to the method described in GB / T 1771-2007.

[0109] (4) Salt water resistance: Tested according to the method described in GB / T 1763.

[0110] (5) Stain resistance: (5.1) Visual inspection. The sample to be tested is immersed in shallow seawater for 12 months, and the area of ​​fouling of the sample is observed. If the area of ​​fouling of the sample is <3%, it is marked with “☆”; if the area of ​​fouling of the sample is 3%-5%, it is marked with “★”; if the area of ​​fouling of the sample is 5%-10%, it is marked with “◇”; if the area of ​​fouling of the sample is >10%, it is marked with “×”.

[0111] (5.2) Visual inspection. The sample to be tested was immersed in shallow seawater for 12 months, and the number of barnacles on the sample surface was observed. The number of barnacles was marked as "very few", "few", "many", "quite a lot" and "a lot".

[0112] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A marine anti-corrosion coating containing graphene-based additives, characterized in that, This is a two-component coating, comprising the following raw materials in parts by weight: Component A: 100 parts of film-forming resin; 0.5-2.0 parts of graphene-based additives; Zinc oxide 1.0-3.0 parts; 5.0-10.0 parts of sheet-like shielding filler; 5.0-10.0 parts of inert filler; Dispersant 1.0-2.0 parts; Defoamer 0.1-0.3 parts; Leveling agent 0.5-1.0 parts; 5-20 parts deionized water; Component B: 15-30 parts of water-based isocyanate curing agent; The graphene-based additive is a double-shell core-shell structure of polyphenol / nitrogen-doped titanium oxide-coated graphene, comprising a conductive graphene core layer, a nitrogen-doped titanium oxide first shell layer, and a second shell layer coated with polyphenol. Furthermore, a metal ion crosslinking agent solution is added to the coating before application, causing the graphene-based additives to undergo in-situ coordination crosslinking.

2. The marine anti-corrosion coating containing graphene-based additives according to claim 1, characterized in that, The film-forming resin is a mixture of aqueous hydroxyl acrylic resin and epoxy emulsion in a weight ratio of 2-4 / 1; and The waterborne hydroxyl acrylic resin has a solid content of 40-50% and a hydroxyl content (based on solids) of 2.0-2.5%. The epoxy emulsion has a solid content of 40-50%.

3. The marine anti-corrosion coating containing graphene-based additives according to claim 1, characterized in that, The graphene-based additive includes the following preparation steps: S11, graphene, titanium source and nitrogen source are subjected to hydrolysis-deposition reaction to obtain nitrogen-doped titanium oxide-coated graphene precursor; S12, the product of S11 is nitrided to obtain nitrogen-doped titanium oxide-coated graphene; S13 involves placing the product of S12 into a polyphenol solution for a self-assembly reaction to obtain a double-shell core-shell structure of polyphenol / nitrogen-doped titanium dioxide-coated graphene, which is the target product.

4. The marine anti-corrosion coating containing graphene-based additives according to claim 3, characterized in that, The ratio of graphene, titanium source, and nitrogen source used is 1g:0.5-2.0g:0.2-3.0g; and The graphene is rGO; The titanium source is tetraisopropyl titanate, titanium isopropoxide, or tetrabutyl titanate. The nitrogen source is urea or melamine.

5. The marine anti-corrosion coating containing graphene-based additives according to claim 3, characterized in that, The nitriding treatment is carried out in a nitrogen or nitrogen / ammonia mixed environment at 400-500℃ for 1.0-3.0h.

6. The marine anti-corrosion coating containing graphene-based additives according to claim 3, characterized in that, The concentration of the polyphenol solution is 0.5-2.0 g / L; and The polyphenols are tannic acid, gallic acid, or catechin.

7. The marine anti-corrosion coating containing graphene-based additives according to claim 1, characterized in that, The particle size of the zinc oxide is ;as well as The sheet-like shielding filler is selected from one or more of glass flakes, mica powder, and sheet-like silicates to synergistically form a multi-scale labyrinth effect with the graphene sheets.

8. The marine anti-corrosion coating containing graphene-based additives according to claim 1, characterized in that, The metal ion crosslinking agent includes Crosslinking agent and / or Crosslinking agent; and The The amount of crosslinking agent used is 0.1-0.3 wt% of the total solids. The The amount of crosslinking agent used is 0.05-0.15 wt% of the total solids.

9. The marine anti-corrosion coating containing graphene-based additives according to claim 1, characterized in that, The preparation method of its component A includes the following steps: S21: Add film-forming resin, zinc oxide, sheet-like shielding filler, inert filler, dispersant, defoamer, leveling agent and some deionized water to the reaction vessel, stir at low speed to mix evenly, and then stir at high speed for 2-3 hours to obtain slurry; S22: Add graphene-based additives and remaining deionized water; stir at low speed for 0.5 h, then ultrasonically disperse for 30 min to obtain a dispersion; S23: Add the dispersion from S22 to the mixed solution from S21, stir until homogeneous, and obtain component A.

10. A coating prepared from the marine anti-corrosion coating containing graphene-based additives according to any one of claims 1-9, characterized in that, It is a single-layer coating suitable for marine steel structures, ships, offshore platforms and port facilities.

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