On-rust anticorrosive paint based on graphene metal organic framework composite material and preparation method of on-rust anticorrosive paint

Abstract

The invention discloses a graphene / metal organic framework composite on-rust anticorrosive coating and a preparation method thereof. The coating takes film-forming resin as a matrix, takes a composite material prepared by growing ZIF-8 on the surface of graphene oxide in situ as a core functional filler, and is supplemented with an active rust conversion agent, a corrosion inhibition pigment, an auxiliary agent and a solvent. The composite material has the innovation points that the composite material not only can construct a super-compact physical shielding network, but also can intelligently respond to pH change when corrosion occurs, dissociate and release zinc ions and corrosion inhibition ligands, and cooperate with benzotriazole released in corrosion inhibition pigments to realize active self-repairing of coating defects. The coating disclosed by the invention can be directly coated on the rusty metal surface, has the advantages of strong adhesive force, long anti-corrosion service life, intelligent protection and the like, and is suitable for long-acting protection of a steel structure in a severe environment.

Description

Technical Field

[0001] This invention relates to the field of metal anti-corrosion coating technology, specifically to a long-lasting anti-corrosion coating that can be directly applied to rusty metal surfaces and has intelligent response and self-healing functions, as well as its preparation method. Background Technology

[0002] Effective corrosion protection for metal structures is a task of significant economic and social value. Among numerous corrosion prevention methods, coating protection has become the most widely used and common anti-corrosion measure due to its advantages such as simple construction, relatively low cost, strong adaptability, and significant protective effect. Protective coatings form a continuous and dense isolation film on the metal surface, physically blocking the contact between corrosive media and the metal substrate. Some coatings also possess chemical corrosion inhibition or electrochemical protection functions, thereby greatly delaying or preventing the corrosion process.

[0003] A complete and efficient anti-corrosion coating system's performance largely depends on the quality of the initial surface preparation. Traditional coating processes require the metal substrate to be in a near-pure state, achieving a Sa 2.5 level (very thorough blast cleaning) or St3 level (very thorough manual and power tool cleaning) as specified in ISO 8501-1, to completely remove mill scale, rust, oil, and other contaminants. Both theoretical research and engineering practice have proven that incomplete surface preparation is the leading cause of premature coating failure.

[0004] In real-world engineering applications, achieving ideal surface treatment often presents significant challenges, creating an urgent need for "rust-resistant application" technology. Rust-resistant anti-corrosion coatings can significantly simplify the application process and reduce anti-corrosion costs, but their long-term protective performance remains a technical hurdle. Existing technologies mainly suffer from the following problems:

[0005] First, the physical shielding performance is insufficient. There are interface defects between traditional fillers and the resin matrix, allowing corrosive media such as water, oxygen, and chloride ions to penetrate along these pathways.

[0006] Second, their functions are limited and passive. Most products rely solely on initial rust conversion or physical barrier functions, lacking the ability to actively repair micro-damage to the coating during use.

[0007] Third, high-performance nanomaterials are prone to agglomeration. For example, although graphene has excellent barrier properties, the strong van der Waals forces between its layers make it difficult to disperse evenly in resins, and its chemical interaction with rust layers is weak, resulting in unsatisfactory adhesion and long-term effectiveness.

[0008] Metal-organic frameworks (MOFs) are a class of porous crystalline materials composed of metal ions and organic ligands, which can serve as nanocontainers for corrosion inhibitors. However, the poor dispersion stability of MOFs in coatings and their poor interfacial bonding with the matrix limit their applications.

[0009] Therefore, it is of great significance to develop a coating that can simultaneously achieve ultimate physical shielding, intelligent active protection, and strong adhesion to rusted surfaces. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by providing a graphene / metal-organic framework composite anti-corrosion coating with strong adhesion, excellent anti-corrosion performance, and intelligent self-healing function, as well as its preparation method.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention provides a graphene / metal-organic framework composite anti-corrosion coating, comprising the following components by weight:

[0013] 40-70 parts of film-forming resin;

[0014] 3–15 parts of graphene / metal-organic framework composite material;

[0015] 5-15 parts of active rust converter;

[0016] 5-20 parts of corrosion-inhibiting pigment;

[0017] 1-5 parts of auxiliary agent;

[0018] Solvent 20-40 parts;

[0019] According to the present invention, the graphene / metal-organic framework composite material is a hybrid material formed by in-situ growth of zeolite imidazole ester framework material ZIF-8 on the surface of graphene oxide.

[0020] According to the present invention, the film-forming resin is one of epoxy resin, waterborne epoxy resin, acrylic resin or fluorocarbon resin.

[0021] According to the present invention, the corrosion-inhibiting pigment is mesoporous silica nanoparticles loaded with benzotriazole.

[0022] According to the present invention, the active rust converter is one or more of tannic acid, phytic acid, or sodium gluconate.

[0023] According to the present invention, the additives include dispersants, leveling agents and defoamers; the solvent is one or more of water, propylene glycol methyl ether acetate or xylene.

[0024] This invention provides a method for preparing the above-mentioned graphene / metal-organic framework composite material, comprising the following steps:

[0025] (1) Graphene oxide is dispersed in a first organic solvent and ultrasonically treated to obtain a graphene oxide dispersion.

[0026] (2) Dissolve 2-methylimidazole in a second organic solvent and add the graphene oxide dispersion obtained in step (1) to form a mixture;

[0027] (3) Dissolve zinc nitrate hexahydrate in a third organic solvent and slowly add it dropwise to the mixture obtained in step (2), and stir the mixture at room temperature.

[0028] (4) The reaction product obtained in step (3) is centrifuged, repeatedly washed with an organic washing solvent, and vacuum dried at 50℃~70℃ to obtain the graphene-supported ZIF-8 composite material powder.

[0029] According to the present invention, the first organic solvent, the second organic solvent and the third organic solvent in steps (1), (2) and (3) are independently methanol or ethanol; the organic washing solvent in step (4) is methanol or ethanol.

[0030] According to the present invention, the size of the graphene oxide in step (1) is 1 μm to 100 μm, and the mass of the graphene oxide is 50 mg to 200 mg.

[0031] According to the present invention, the volume of the first organic solvent in step (1) is 100 mL to 300 mL, and the ultrasonic treatment time is 1 h to 4 h;

[0032] According to the present invention, the mass of the 2-methylimidazole in step (2) is 1.0 g to 2.0 g;

[0033] According to the present invention, the volume of the second organic solvent in step (2) is 40 mL to 60 mL;

[0034] According to the present invention, the mass of zinc nitrate hexahydrate in step (3) is 0.5g to 1.0g;

[0035] According to the present invention, the volume of the third organic solvent in step (3) is 40 mL to 60 mL, and the stirring reaction time is 2 h to 6 h;

[0036] According to the present invention, the mass ratio of graphene oxide to zinc nitrate hexahydrate is 1:5 to 1:10, and the molar ratio of 2-methylimidazole to zinc nitrate hexahydrate is 4:1 to 10:1.

[0037] This invention provides a method for preparing the above-mentioned mesoporous silica nanoparticles loaded with benzotriazole, specifically including the following steps:

[0038] S1. Place the mesoporous silica nanoparticles in a vacuum drying oven to dry them, in order to remove moisture and adsorbates from the pores.

[0039] S2. Dissolve benzotriazole in anhydrous ethanol and sonicate to ensure complete dissolution of benzotriazole, resulting in a clear and transparent solution.

[0040] S3. Add the pretreated mesoporous silica nanoparticles from step 1 to the benzotriazole solution prepared in step 2, and heat in an oil bath while stirring under gentle reflux for a period of time.

[0041] S4. The above mixed dispersion was filtered to obtain a filter cake, which was then washed several times with ethanol to remove residual benzotriazole on the surface. After drying in a vacuum oven, mesoporous silica nanoparticle powder loaded with benzotriazole was obtained.

[0042] According to the present invention, the specific surface area of ​​the mesoporous silica in step S1 is 600-1000 m². 2 / g, preferably 800-900m 2 / g; pore size is 2-8nm, preferably 3-5nm.

[0043] According to the present invention, the vacuum drying temperature in step S1 is 60-80°C and the time is 6-12 hours.

[0044] According to the present invention, the concentration of the benzotriazole ethanol solution in step S2 is 10-50 mg / mL, preferably 20-30 mg / mL.

[0045] According to the present invention, the ultrasonic treatment in step S2 has a power of 300W and a duration of 10 to 20 minutes.

[0046] According to the present invention, the mass ratio of mesoporous silica to benzotriazole in step S3 is 1:(0.1 to 0.5), preferably 1:(0.2 to 0.3).

[0047] According to the present invention, the heating temperature in step S3 is 70-80°C, and the reflux stirring time is 6-8 hours.

[0048] According to the present invention, the number of ethanol rinsing steps in step S4 is 2-5 times, and the drying temperature is 60-80°C.

[0049] The present invention also provides a method for preparing the above-mentioned rust-resistant anti-corrosion coating, comprising the following steps:

[0050] (a) Pre-dispersion: The film-forming resin, part of the solvent, additives and graphene / metal-organic framework composite material are mixed according to the formula and then subjected to high-speed shear dispersion;

[0051] (b) Grinding: Grind the mixture obtained in step (a) until the fineness is no greater than 30 μm;

[0052] (c) Preparation: Under stirring conditions, add active rust converter, corrosion inhibitor pigment and remaining solvent to the slurry after grinding in step (b), and mix evenly;

[0053] (d) Filtration: Filter the mixture obtained in step (c) to obtain the rust-resistant anti-corrosion coating.

[0054] According to the present invention, the film-forming resin in step (a) is one of epoxy resin, waterborne epoxy resin, acrylic resin or fluorocarbon resin, and the amount added is 40 to 70 parts.

[0055] According to the present invention, the graphene / metal-organic framework composite material in step (a) is a hybrid material formed by in-situ growth of zeolite imidazole ester framework material ZIF-8 on the surface of graphene oxide, and the amount added is 3 to 15 parts.

[0056] According to the present invention, the additives in step (a) include dispersants, leveling agents and defoamers; the solvent is one or more of water, propylene glycol methyl ether acetate or xylene, and the amount added is 1 to 5 parts.

[0057] According to the present invention, the corrosion-inhibiting pigment in step (c) is mesoporous silica nanoparticles loaded with benzotriazole, and the amount added is 5 to 20 parts.

[0058] According to the present invention, the active rust converter in step (c) is one or more of tannic acid, phytic acid or sodium gluconate, and the amount added is 5 to 15 parts.

[0059] The beneficial effects of this invention are as follows:

[0060] Synergistic physical shielding: This invention anchors ZIF-8 crystals onto graphene sheets using an in-situ growth method, effectively preventing the graphene from re-stacking. ZIF-8, acting as a "nanospacer," together with the graphene sheets, constructs a labyrinthine barrier path, significantly extending the diffusion path of corrosive media and forming a dense and stable physical barrier.

[0061] Intelligent self-healing function: The core innovation of this invention lies in the introduction of an intelligent response mechanism. When localized damage and corrosion occur in the coating, the pH value of the local microenvironment increases, and the ZIF-8 structure will responsively dissociate, releasing Zn. 2 The α-methylimidazole ligand reacts with hydroxide ions to form Zn(OH)2 precipitate, which can physically block microcracks; at the same time, the released 2-methylimidazole ligand can be adsorbed on the metal surface as an organic corrosion inhibitor. This process, together with the benzotriazole released from mesoporous silica, constitutes a dual intelligent slow-release system, realizing the active repair of coating defects.

[0062] Excellent application performance in rust-affected areas: The coating system has good penetration, allowing it to reach deep into the rust layer. The active rust converter and the intelligently released corrosion inhibitor work synergistically to transform unstable iron oxides into a stable protective layer, forming a strong and durable adhesion together with the film-forming resin.

[0063] Environmentally friendly and long-lasting: This technology is compatible with water-based resin systems, reducing VOC emissions. The presence of composite materials significantly improves the coating's durability and service life, reducing maintenance requirements and total lifespan costs. Detailed Implementation

[0064] The present invention will be further described below with reference to embodiments. It should be noted that the following embodiments are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0065] Example 1:

[0066] (1) Preparation of G@MOF: 100 mg of graphene oxide was dispersed in 200 mL of methanol and sonicated for 2 hours. 1.64 g of 2-methylimidazole was dissolved in 50 mL of methanol and added to the above dispersion. 0.74 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol and slowly added dropwise to the mixture. The mixture was stirred at room temperature for 4 hours. After centrifugation, washing, and vacuum drying at 60 °C, the composite material powder was obtained.

[0067] (2) Coating preparation:

[0068] Pre-dispersion: Add 50 parts epoxy resin (E-44), 10 parts propylene glycol methyl ether acetate, 0.5 parts dispersant and 8 parts composite material into the mixing tank and disperse at 1200 rpm for 40 minutes.

[0069] Grinding: Transfer the pre-dispersed slurry to a sand mill and grind it to a fineness of 25μm.

[0070] Preparation: Add 5 parts phytic acid, 10 parts BTA-loaded mesoporous silica, 0.3 parts leveling agent, 0.2 parts defoamer and the remaining solvent to the slurry, and stir at 500 rpm for 40 minutes.

[0071] Filtration: Filter with a 200-mesh filter to obtain a solvent-based rust-resistant anti-corrosion coating.

[0072] Example 2:

[0073] (1) G@MOF preparation: Same as in Example 1.

[0074] (2) Coating preparation: 50 parts of waterborne acrylic resin, 15 parts of deionized water, 1 part of waterborne dispersant and 5 parts of composite material were dispersed at high speed. The subsequent steps were the same as in Example 1, with the addition of 8 parts of tannic acid, 8 parts of BTA-loaded mesoporous silica and corresponding additives to obtain a waterborne rust-resistant anti-corrosion coating.

[0075] Comparative Example 3: A commercially available brand of epoxy anti-rust coating.

[0076] Performance testing

[0077] The coatings obtained in Examples 1 and 2 of this invention, along with the comparative coating, were respectively applied to Q235 carbon steel plates with a uniform rust layer, dried, and then tested. The results are shown in the table below.

[0078] Testing items Testing standards Example 1 Example 2 Comparative Example Adhesion / Grade GB / T 9286-1998 0 0 1 Resistance to neutral salt spray / h GB / T 1771-2007 1500 1200 500 Scratch self-healing efficiency / % / >90 >85 - Water resistance (30 days) GB / T 1733-1993 No abnormalities No abnormalities foaming

[0079] Test results show that the coating provided by this invention is significantly superior to the comparative product in terms of adhesion, corrosion resistance, and intelligent self-healing function.

Claims

1. A rust-resistant anti-corrosion coating, characterized in that, Based on parts by weight, it comprises the following components: 40-70 parts of film-forming resin; 3–15 parts of graphene / metal-organic framework composite material; 5-15 parts of active rust converter; 5-20 parts of corrosion-inhibiting pigment; 1-5 parts of auxiliary agent; Solvent 20-40 parts; The graphene / metal-organic framework composite material is a hybrid material formed by in-situ growth of zeolite imidazole ester framework material ZIF-8 on the surface of graphene oxide, and the corrosion-inhibiting pigment is mesoporous silica nanoparticles loaded with benzotriazole.

2. The anti-corrosion coating for rust-bearing materials according to claim 1, characterized in that, The film-forming resin is one of epoxy resin, waterborne epoxy resin, acrylic resin, or fluorocarbon resin.

3. The anti-corrosion coating for rust-bearing materials according to claim 1, characterized in that, The active rust converter is one or more of tannic acid, phytic acid, or sodium gluconate.

4. A method for preparing a graphene / metal-organic framework composite material for use in the rust-resistant anti-corrosion coating of claim 1, characterized in that, Includes the following steps: (1) Disperse 50mg to 200mg of graphene oxide with a size of 1μm to 100μm in 100mL to 300mL of a first organic solvent and sonicate for 1h to 4h to obtain a graphene oxide dispersion. (2) Dissolve 1.0g to 2.0g of 2-methylimidazole in 40mL to 60mL of a second organic solvent, and add the graphene oxide dispersion obtained in step (1) to form a mixture; (3) Dissolve 0.5g to 1.0g of zinc nitrate hexahydrate in 40mL to 60mL of a third organic solvent, and slowly add it dropwise to the mixture obtained in step (2), and stir the mixture at room temperature for 2h to 6h. (4) The reaction product obtained in step (3) is centrifuged, washed repeatedly with an organic washing solvent, and dried under vacuum at 50℃~70℃ to obtain the graphene-supported ZIF-8 composite material powder.

5. The graphene / metal-organic framework composite material according to claim 6, wherein the first organic solvent, the second organic solvent and the third organic solvent in steps (1), (2) and (3) are independently methanol or ethanol; and the organic washing solvent in step (4) is methanol or ethanol.

6. The graphene / metal-organic framework composite material according to claim 6, wherein the mass ratio of graphene oxide to zinc nitrate hexahydrate is 1:5 to 1:10, and the molar ratio of 2-methylimidazole to zinc nitrate hexahydrate is 4:1 to 10:

1.

7. A method for preparing mesoporous silica nanoparticles loaded with benzotriazole as described in claim 1, characterized in that, Includes the following steps: S1. Place the mesoporous silica nanoparticles in a vacuum drying oven at 60-80℃ for 6-12 hours to dry them, in order to remove moisture and adsorbents from the pores. S2. Dissolve benzotriazole in anhydrous ethanol at a concentration of 10–50 mg / mL, and sonicate for 10–20 minutes to ensure complete dissolution of benzotriazole, resulting in a clear and transparent solution. S3. Add the pretreated mesoporous silica nanoparticles from step S1 to the benzotriazole solution prepared in step 2, and heat in an oil bath at 70-80°C, stirring under gentle reflux for 6-8 hours. S4. Filter the above mixed dispersion to obtain a filter cake, wash it with ethanol 2-5 times to remove residual benzotriazole on the surface, and then dry it in a vacuum oven at 60-80℃ to obtain mesoporous silica nanoparticle powder loaded with benzotriazole.

8. The mesoporous silica nanoparticles loaded with benzotriazole according to claim 7, characterized in that, The specific surface area of ​​the mesoporous silica mentioned in step S1 is 600-1000 m². 2 / g, with a pore size of 2-8nm.

9. The mesoporous silica nanoparticles loaded with benzotriazole according to claim 7, wherein the mass ratio of mesoporous silica to benzotriazole in step S3 is 1:(0.1-0.5), preferably 1: (0.2～0.3)。 10. A method for preparing a rust-resistant anti-corrosion coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (a) Pre-dispersion: The film-forming resin, part of the solvent, additives and graphene / metal-organic framework composite material are mixed according to the formula and then subjected to high-speed shear dispersion; (b) Grinding: Grind the mixture obtained in step (a) until the fineness is no greater than 30 μm; (c) Preparation: Under stirring conditions, add active rust converter, corrosion inhibitor pigment and remaining solvent to the slurry after grinding in step (b), and mix evenly; (d) Filtration: Filter the mixture obtained in step (c) to obtain the rust-resistant anti-corrosion coating.