Intelligent self-repairing epoxy zinc-rich coating based on MOFs material and preparation method of intelligent self-repairing epoxy zinc-rich coating

Abstract

The invention relates to the technical field of epoxy zinc-rich coatings, in particular to an intelligent self-repairing epoxy zinc-rich coating based on an MOFs material and a preparation method of the intelligent self-repairing epoxy zinc-rich coating. The intelligent self-repairing epoxy zinc-rich coating based on the MOFs material comprises the following components in percentage by mass: 0.25%-1.0% of a BTA (at) ZIF-8 / CNTs composite material, 40%-60% of zinc powder, 30%-45% of epoxy resin and 10%-15% of a curing agent. The BTA-coated ZIF-8 / CNTs composite material is introduced as a functional filler, the structural compactness and corrosion resistance of the coating are enhanced while the sacrificial anode effect of the zinc powder is maintained, the service life of a metal matrix in a complex service environment can be remarkably prolonged, and the coating is suitable for various fields such as ocean structures, bridges and petrochemical devices. The method has wide application prospects in the field of metal matrix surface protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of epoxy zinc-rich coating, and particularly relates to an intelligent self-repairing epoxy zinc-rich coating based on MOFs material and a preparation method thereof. BACKGROUND

[0002] The wide application of metal materials in the fields of ships, bridges, chemical equipment and ocean engineering makes them face the severe challenge of corrosion environment such as moisture, salt spray and acidic medium for a long time, resulting in degradation of structural performance and even failure. As an important heavy anti-corrosion method, the epoxy zinc-rich coating mainly relies on the sacrificial anode effect of zinc powder and the physical barrier effect of the epoxy resin matrix to provide protection. However, in practical application, it is found that the traditional epoxy zinc-rich coating has inherent defects such as low utilization rate of zinc powder, lack of self-repairing ability and insufficient long-term protection performance. Under the action of corrosive environment, zinc powder in the traditional epoxy zinc-rich coating will preferentially undergo oxidation reaction, forming local galvanic corrosion, resulting in rapid consumption of zinc particles. At the same time, the microcracks generated in the coating under the action of mechanical stress or environmental aging are difficult to repair, so that the corrosive medium continuously penetrates to the surface of the metal substrate, eventually leading to failure of protection.

[0003] Metal organic framework (MOFs) material has great potential in the field of anti-corrosion coating due to its highly ordered pore structure, excellent adsorption performance and controllable functional groups. The porous structure of MOFs material helps to improve the dispersibility of zinc powder, enhance the compactness and mechanical properties of the coating, and thus improve the overall corrosion resistance. Therefore, in order to enhance the corrosion resistance of the epoxy zinc-rich coating, developing an intelligent self-repairing epoxy zinc-rich coating based on MOFs material has become one of the effective methods. The introduction of MOFs material in the coating not only can build an efficient physical barrier inside the coating to reduce the penetration of corrosive medium, but also can load corrosion inhibitors to form an intelligent response system, slowly release active substances when corrosion occurs, and realize self-repairing function.

[0004] Chinese patent application with publication number CN115678411A discloses a preparation method of a GO / Ce-MOF@PDA / PU super-hydrophobic self-repairing anti-corrosion coating. This technology uses Ce-MOF to load corrosion inhibitors to achieve the self-repairing function of the coating. Chinese patent application with publication number CN117126583A uses graphene oxide modified by corrosion inhibitors to enhance the zinc-rich epoxy coating. Through the "labyrinth effect" of graphene, the penetration path of corrosion medium is prolonged, and more attachment sites are provided for the further loading of corrosion inhibitors, so as to delay corrosion and significantly enhance the corrosion resistance of the coating. It can be seen that the synergistic effect of carbon nanomaterials and corrosion inhibitors can effectively improve the corrosion resistance of zinc-rich coatings: on the one hand, carbon nanomaterials can construct a conductive network in the coating, enhance the electronic connection between zinc powder, and improve the efficiency of the sacrificial anode effect; on the other hand, corrosion inhibitors can release active ingredients when corrosion occurs, slowing down the corrosion process of the metal matrix. However, the release behavior of corrosion inhibitors loaded directly on the surface of carbon nanomaterials is often affected by environmental response lag, insufficient interface stability, and other factors, which easily leads to premature leakage or residual failure problems, making it difficult to achieve a controlled release process on demand.

[0005] To overcome the problem of controlled release, some current researches attempt to use MOFs nanocapsules to load corrosion inhibitors. However, in practical applications, when MOFs materials are added as inorganic fillers to the coating system, they often destroy the continuous conductive network constructed by carbon nanomaterials, hinder the electron conduction path, and reduce the sacrificial anode protection efficiency of zinc powder. Therefore, how to maintain the integrity of the conductive network while constructing an intelligent controlled release system, and how to achieve the balance between corrosion inhibition and electrical conductivity, are still key challenges in the current functional composite design of zinc-rich coatings. SUMMARY

[0006] To overcome the problems of low utilization rate of zinc powder, insufficient self-repairing ability, and poor environmental adaptability of existing zinc-rich epoxy coatings during long-term service, the present application provides an intelligent self-repairing zinc-rich epoxy coating based on MOFs materials and its preparation method and application. The coating is prepared by modifying carbon nanotube materials with corrosion inhibitor-loaded MOF particles and compounding them with zinc-rich epoxy resin to construct a zinc-rich epoxy coating with self-healing performance. This system not only can achieve precise self-repairing of corrosion microzones, but also can significantly improve the mechanical properties and long-term corrosion resistance of the coating, thereby effectively prolonging the service life of the metal substrate in harsh environments.

[0007] The present application provides an intelligent self-repairing zinc-rich epoxy coating based on MOFs materials, which comprises the following components by mass percentage: BTA@ZIF-8 / CNTs composite material 0.25%~1%, zinc powder 49~49.75%, epoxy resin 37.5%, and curing agent 12.5%.

[0008] Further, the preparation method of the BTA@ZIF-8 / CNTs composite material comprises the following steps: hydroxylated carbon nanotubes and benzotriazole (BTA) are added into methanol, and ultrasonic dispersion is carried out for 20-30 min to obtain solution C; zinc nitrate hexahydrate is dissolved in methanol, and is marked as solution D; 2-methylimidazole is dissolved in methanol, and is marked as solution E; solution C is added into solution D, and after stirring for 20-30 min, solution E is slowly added, and reaction is carried out for 20-26 h; after the reaction is completed, the product is collected by centrifugation, washed with methanol for 3-5 times, and dried at 60-80℃ for 20-24 h to obtain the BTA@ZIF-8 / CNTs composite material.

[0009] Preferably, the mass ratio of the hydroxylated carbon nanotubes, benzotriazole, zinc nitrate hexahydrate and 2-methylimidazole is 1:7:1:22.

[0010] Further, the epoxy resin is epoxy resin E44.

[0011] Further, the curing agent is an epoxy curing agent, such as epoxy curing agent 650 or epoxy curing agent 3388.

[0012] The application also provides a preparation method of an intelligent self-repairing epoxy zinc-rich coating based on MOFs material, comprising the following steps: Step one, the BTA@ZIF-8 / CNTs composite material is dispersed in a mixed solvent, and ultrasonic treatment is carried out for 30-60 min to obtain a dispersion liquid; zinc powder and an epoxy resin are added into the dispersion liquid, and after stirring for 30-60 min, ultrasonic treatment is carried out for 15-30 min to obtain component A; a curing agent is used as component B.

[0013] Further, the mixed solvent is prepared by mixing dimethylbenzene and n-butanol at a volume ratio of (1.5-2.0):1 (preferably 1.6:1).

[0014] Preferably, the particle size of the zinc powder is 400-600 mesh.

[0015] Step two, component A and component B are mixed, and ultrasonic stirring is carried out for 10-20 min to obtain a uniform coating slurry. The slurry is coated on the surface of a pretreated metal substrate by spraying or brushing, and after room temperature curing for 10-12 h, curing at 60-80℃ for 4-8 h, an epoxy zinc-rich composite coating with a dry film thickness of 60-270 μm is finally formed.

[0016] Preferably, the mass ratio of component A to component B is 7:1, and the content of the curing agent in the final coating is 12.5%.

[0017] Preferably, the metal substrate pretreatment includes sanding to remove the oxide layer, ultrasonic cleaning with alcohol for 20-30 minutes, and blowing dry for standby.

[0018] Preferably, the spraying pressure is 0.2-0.5 MPa, and the spraying distance is 15-30 cm.

[0019] Preferably, the curing process adopts a stepwise temperature rise: after curing at room temperature for 12 hours, curing at 60 DEG C for 4 hours.

[0020] Preferably, the hydroxylated carbon nanotube has a diameter of 10-20 nm and a length of 0.5-2 mu m.

[0021] The MOFs material-based intelligent self-repairing epoxy zinc-rich coating prepared by the method is suitable for long-term protection in harsh corrosive environments such as marine engineering, bridge steel structure, and petrochemical equipment.

[0022] The present application has the following advantages: (1) The present application loads the corrosion inhibitor benzotriazole (BTA) in the metal organic framework material ZIF-8 to construct a BTA@ZIF-8 / CNTs composite material, realizes intelligent release of the corrosion inhibitor, effectively improves the self-repairing ability and long-term corrosion resistance of the coating. Meanwhile, the stable structure of ZIF-8 does not block the conductive network constructed by the carbon nanotubes while loading the corrosion inhibitor, thereby retaining the excellent conductivity and mechanical enhancement characteristics of CNTs, solving the problem that traditional nano containers easily interfere with the enhancement effect of carbon nanomaterials. The synergistic design takes into account the electrochemical protection performance and structural compactness of the coating, significantly improves the comprehensive protection performance of the epoxy zinc-rich coating, and has good practicability and application prospect.

[0023] (2) The present application modifies the carbon nanotubes with ZIF-8 and loads the corrosion inhibitor BTA to construct an epoxy zinc-rich coating with self-healing performance. The porous structure of ZIF-8 not only effectively improves the dispersibility of the carbon nanotubes in the epoxy resin and reduces the agglomeration of the carbon nanotubes, but also loads the corrosion inhibitor BTA through the highly ordered pore structure, triggers intelligent release of the corrosion inhibitor when the pH value of the corrosion micro-area changes, forms a protective film, and realizes the self-repairing function of the coating. In addition, the introduction of the carbon nanotubes enhances the mechanical strength and conductivity of the coating, improves the sacrificial anode effect of the zinc powder, and significantly improves the long-term protection performance of the coating.

[0024] (3) The present application optimizes the preparation process of the BTA@ZIF-8 / CNTs composite material to realize efficient loading and controlled release of the corrosion inhibitor. The surface modification of the carbon nanotubes further enhances the interfacial bonding force between the composite material and the epoxy resin, effectively prevents microcracks in the coating under mechanical stress or environmental aging, and thereby prolongs the service life of the coating.

[0025] (4) The prepared intelligent self-repairing epoxy zinc-rich coating has excellent corrosion resistance and environmental adaptability, and is suitable for long-acting protection in harsh corrosive environments such as marine engineering, bridge steel structure, petroleum and chemical equipment. The step curing process of the coating ensures the full crosslinking of the epoxy resin and the curing agent, further improving the compactness and adhesion of the coating. In addition, the preparation method is simple in operation, low in cost, easy to industrialize, and has broad market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 (a) is a micro-morphology diagram of ZIF-8 powder, and (b) is a micro-morphology diagram of the BTA@ZIF-8 / CNTs composite material prepared in Example 1; Figure 2 The infrared spectrum of the carbon nanotube, the ZIF-8 powder prepared in Comparative Example 2, the ZIF-8 / CNTs hybrid material prepared in Comparative Example 3, and the BTA@ZIF-8 / CNTs composite material prepared in Example 1; Figure 3 The X-ray diffraction pattern of the carbon nanotube, the ZIF-8 powder prepared in Comparative Example 2, the ZIF-8 / CNTs hybrid material prepared in Comparative Example 3, and the BTA@ZIF-8 / CNTs composite material prepared in Example 1; Figure 4 The electrochemical polarization curve of the coating prepared in Examples 1-4 and Comparative Examples 1-8. DETAILED DESCRIPTION

[0027] In order to further illustrate the present application, a kind of intelligent self-repairing epoxy zinc-rich coating based on MOFs material and its preparation method and application provided by the present application are described in detail below in conjunction with the drawings and examples, but it cannot be understood as limiting the scope of protection of the present application.

[0028] Electrochemical performance test: CHI660-E type electrochemical workstation was used for electrochemical test. Platinum electrode and Ag / AgCl electrode (3M) in saturated KCl solution were used as the contrast electrode and reference electrode, respectively. Before the test, the epoxy zinc composite coating surface was taken as the working surface, and the rest of the surface was packaged and insulated with silicone rubber. During the test, the sample was immersed in 3.5 wt.% sodium chloride solution with an area of about 1 cm 2 . The voltammetry polarization scanning rate was 2 mV s -1 . To ensure the reliability of the results, three repeated parallel measurements were carried out for each test.

[0029] The metal substrate used in the following examples and comparative examples was Q235.

[0030] The epoxy resin E44 used in the following examples and comparative examples was purchased from Shanghai Macklin Biochemical Technology Co., Ltd., model E-44, bisphenol A type epoxy resin.

[0031] The hydroxylated carbon nanotubes used in the following examples and comparative examples were purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd., purity > 95%, 10-20 nm, length 0.5-2 μm, and hydroxyl content about 3.06 wt.%.

[0032] The curing agent used in the following examples and comparative examples was purchased from Shanghai Macklin Biochemical Technology Co., Ltd., model epoxy curing agent 650, amine value about 200-240 mgKOH / g, and viscosity (40℃): 15000-35000 mpa.s.

[0033] Example 1

[0034] (1) 0.1 g of hydroxylated carbon nanotubes and 0.7 g of benzotriazole (BTA) were added to 15 mL of methanol and ultrasonically dispersed for 30 minutes to prepare a BTA solution. 1 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol to prepare a zinc nitrate solution, and 2.2 g of 2-methylimidazole was dissolved in 35 mL of methanol to prepare a 2-methylimidazole solution. The BTA solution was added to the zinc nitrate solution, and after stirring for 20 minutes, the 2-methylimidazole solution was added, and the reaction was allowed to stand for 24 hours. After centrifugal washing, drying was carried out at 60℃ for 24 hours to obtain a BTA@ZIF-8 / CNTs composite material.

[0035] (2) 0.01 g of the BTA@ZIF-8 / CNTs composite material was added to 0.8 mL of dimethylbenzene and 0.5 mL of n-butanol, and ultrasonically dispersed for 40 minutes. 2.0 g of zinc powder and 1.5 g of epoxy resin E44 were added, and after mechanical stirring for 40 minutes and ultrasonic stirring for 20 minutes, component A was obtained. Component A was mixed with a curing agent at a mass ratio of 7:1, ultrasonic stirring was carried out for 15 minutes to obtain a composite coating, wherein the mass percentages of the BTA@ZIF-8 / CNTs composite material, zinc powder, epoxy resin and curing agent are as follows: BTA@ZIF-8 / CNTs composite material 0.25%, zinc powder 49.75%, epoxy resin 37.5%, and curing agent 12.5%.

[0036] (3) The surface of the metal substrate was roughened and pretreated. First, coarse sandpaper was used to remove surface rust and surface oxide layer, and then the surface swarf was preliminarily washed away by flowing water; then the surface was ultrasonically cleaned by an ultrasonic cleaning machine, the cleaning solution was alcohol, and the cleaning time was 30 minutes; finally, the surface of the metal substrate was dried by a hair dryer.

[0037] (4) The composite coating was uniformly coated on the pretreated surface of the metal substrate by spraying, and the coating thickness was controlled at 90 μm.

[0038] (5) The coating is cured by a stepwise temperature rising process: 12 hours at room temperature, and 4 hours at 60°C.

[0039] Example 2

[0040] (1) The same as example 1; (2) Different from example 1: the mass percentage of BTA@ZIF-8 / CNTs composite material, zinc powder, epoxy resin and curing agent in the composite coating is as follows: BTA@ZIF-8 / CNTs composite material 0.5%, zinc powder 49.5%, epoxy resin 37.5%, curing agent 12.5%; (3) The same as example 1; (4) The same as example 1; (5) The same as example 1.

[0041] Example 3

[0042] (1) The same as example 1; (2) Different from example 1: the mass percentage of BTA@ZIF-8 / CNTs composite material, zinc powder, epoxy resin and curing agent in the composite coating is as follows: BTA@ZIF-8 / CNTs composite material 0.75%, zinc powder 49.25%, epoxy resin 37.5%, curing agent 12.5%; (3) The same as example 1; (4) The same as example 1; (5) The same as example 1.

[0043] Example 4

[0044] (1) The same as example 1; (2) Different from example 1: the mass percentage of BTA@ZIF-8 / CNTs composite material, zinc powder, epoxy resin and curing agent in the composite coating is as follows: BTA@ZIF-8 / CNTs composite material 1.0%, zinc powder 49%, epoxy resin 37.5%, curing agent 12.5%.

[0045] (3) The same as example 1; (4) The same as example 1; (5) The same as example 1.

[0046] Comparative Example 1

[0047] The epoxy zinc-rich coating was prepared according to the method of Example 3, except that the BTA@ZIF-8 / CNTs composite material was not added, and only an equivalent amount of ZIF-8 was used instead, which was prepared as follows: 1 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol to prepare a zinc nitrate solution, and 2.2 g of 2-methylimidazole was dissolved in 35 mL of methanol to prepare a 2-methylimidazole solution. The 2-methylimidazole solution was added to the zinc nitrate solution, and the reaction was allowed to stand for 24 hours. The resulting precipitate was centrifuged, washed with ethanol, and dried to obtain ZIF-8 powder. The rest of the conditions were the same as in Example 3, and the resulting polarization curve graph and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0048] Comparative Example 2

[0049] The epoxy zinc-rich coating was prepared according to the method of Example 3, except that the BTA@ZIF-8 / CNTs composite material was not added, and only an equivalent amount of BTA was used instead, and the rest of the conditions were the same as in Example 3. The resulting polarization curve graph and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0050] Comparative Example 3

[0051] The epoxy zinc-rich coating was prepared according to the method of Example 3, except that the BTA@ZIF-8 / CNTs composite material was not added, and only an equivalent amount of carbon nanotubes was used instead, and the rest of the conditions were the same as in Example 3. The resulting polarization curve graph and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0052] Comparative Example 4

[0053] The epoxy zinc-rich coating was prepared according to the method of Example 3, except that the BTA@ZIF-8 / CNTs composite material was not added, and only an equivalent amount of ZIF-8 / CNTs hybrid material was used instead, which was prepared as follows: 0.1 g of hydroxylated carbon nanotubes was added to 15 mL of anhydrous methanol and ultrasonically dispersed for 30 minutes to prepare a carbon nanotube dispersion. 1 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol to prepare a zinc nitrate solution, and 2.2 g of 2-methylimidazole was dissolved in 35 mL of methanol to prepare a 2-methylimidazole solution. The zinc nitrate solution was slowly added to the carbon nanotube dispersion, and after stirring for 30 minutes, the 2-methylimidazole solution was added. The reaction was allowed to proceed at room temperature for 20 minutes, and the mixture was allowed to stand for 24 hours. The product was collected by centrifugation and washed with methanol three times, and then dried at 60°C for 24 hours to obtain the ZIF-8 / CNTs hybrid material. The rest of the steps were the same as in Example 3. The resulting polarization curve graph and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0054] Comparative Example 5

[0055] The epoxy zinc-rich coating was prepared according to the method of Example 3, except that the BTA@ZIF-8 / CNTs composite material was not added, and the rest of the conditions were the same as in Example 3. The polarization curve diagram obtained and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0056] Comparative Example 6

[0057] The metal substrate without epoxy zinc-rich coating was used as a blank control example. The metal substrate used was a Q235 carbon steel substrate. The polarization curve diagram obtained and the electrochemical parameters corresponding to the polarization curve are shown in Figure 4 and Table 1.

[0058] Comparative Example 7

[0059] (1) 0.1 g of hydroxylated carbon nanotubes and 0.7 g of benzotriazole (BTA) were added to 15 mL of methanol and ultrasonically dispersed for 30 minutes to prepare a BTA solution. 0.7 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol, and 1.7 g of 2-methylimidazole was dissolved in 35 mL of methanol. The BTA solution was added to the zinc nitrate solution, and after stirring for 20 minutes, the 2-methylimidazole solution was added, and the reaction was allowed to stand for 24 hours. After centrifugal washing, drying was carried out at 60°C for 24 hours to obtain a BTA@ZIF-8 / CNTs composite material; (2) The same as in Example 3; (4) The same as in Example 3; (5) The same as in Example 3; (6) The same as in Example 3.

[0060] Comparative Example 8

[0061] (1) 0.1 g of hydroxylated carbon nanotubes and 0.7 g of benzotriazole (BTA) were added to 15 mL of methanol and ultrasonically dispersed for 30 minutes to prepare a BTA solution. 0.7 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol, and 1.7 g of 2-methylimidazole was dissolved in 35 mL of methanol. The BTA solution was added to the zinc nitrate solution, and after stirring for 20 minutes, the 2-methylimidazole solution was added, and the reaction was allowed to stand for 24 hours. After centrifugal washing, drying was carried out at 60°C for 24 hours to obtain a BTA@ZIF-8 / CNTs composite material.

[0062] (2) The same as in Example 3; (4) The same as in Example 3; (5) The same as in Example 3; (6) The same as in Example 3.

[0063] Table 1 shows the results of the electrochemical performance tests of Examples 1-4 and Comparative Examples 1-8.

[0064] Table 1 Electrochemical performance test of Examples 1-4 and Comparative Examples 1-8

[0065] From Table 1 and Figure 4 It can be seen that the electrochemical performance of different coating systems is significantly different, among which the epoxy zinc-rich coating sample doped with BTA@ZIF-8 / CNTs exhibits more excellent corrosion resistance. With the increase of the addition amount of BTA@ZIF-8 / CNTs, the corrosion current density gradually decreases and the polarization resistance gradually increases, indicating that the composite nano-filler forms a dense barrier structure in the coating, effectively blocking the intrusion of corrosion medium. Among them, when the doping ratio is 0.75%, the coating shows the best corrosion protection performance, with a corrosion current density of only 1.691 x 10 -8 A / cm 2 , and a polarization resistance of 1.064 x 10 6 Ω·cm 2 , which is more than 2 orders of magnitude higher than that of Comparative Example 5 (pure epoxy zinc-rich coating) and Comparative Example 6 (Q235 carbon steel substrate). This shows that the composite filler plays a significant role in improving the density of the coating and enhancing the corrosion resistance barrier.

[0066] Further comparison found that under the condition of the same mass fraction of BTA@ZIF-8 / CNTs, if the ratio of zinc nitrate hexahydrate, BTA and 2-methyl imidazole in its composition is less than 1:7:22, the corrosion resistance of the obtained coating appears a downward trend. This may be due to the change of the ratio of the precursors, resulting in insufficient loading of BTA in the ZIF-8 structure, thereby weakening the intelligent protection ability of the slow-release corrosion inhibitor.

[0067] In addition, ZIF-8 itself is an electrically insulating material, and the relative increase of its content in BTA@ZIF-8 / CNTs will affect the network construction of carbon nanotubes, causing the interruption of the conductive path, and weakening the enhancement effect of carbon nanotubes on the behavior of zinc powder sacrificial anode in the coating. Carbon nanotubes can promote electron migration and improve the release efficiency of zinc powder corrosion products, so the conductivity of carbon nanotubes is essential to enhance the anode protection. When the content of ZIF-8 is too high, the conductive network of carbon nanotubes is destroyed, the anode protection efficiency decreases, and thus the long-term protection ability of the coating as a whole is affected.

[0068] Figure 1 shows the micro-morphology of ZIF-8 powder and the micro-morphology of ZIF-8 particle modified carbon nanotube material. From the figure, it can be seen that the ZIF-8 powder has a regular rhombic polyhedral structure, uniform particle size distribution, smooth surface and good crystal integrity, which is conducive to the formation of a dense barrier structure in the coating. While the Figure 1In the (b), the ZIF-8 particles are uniformly loaded on the surface of the carbon nanotubes to form a relatively compact composite structure, and the carbon nanotubes as a support skeleton significantly improve the dispersion and spatial distribution stability of the ZIF-8, avoiding the occurrence of particle agglomeration.

[0069] In summary, the synergistic effect of ZIF-8 and CNTs significantly improves the comprehensive performance of the zinc-rich epoxy coating: on the one hand, the appropriate loading of CNTs with ZIF-8 can effectively improve the self-repairing ability and long-term corrosion resistance of the coating without affecting the electrical conductivity; on the other hand, the combination of the two not only optimizes the mechanical strength of the coating, but also realizes the efficient loading of the corrosion inhibitor through the rich active sites on the surface of ZIF-8, thereby achieving the unity of long-term protection and functional design of the coating.

[0070] With the above ideal embodiments according to the present application as inspiration, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined by the scope of the claims.

Claims

1. An intelligent self-healing epoxy zinc-rich coating based on MOFs material, characterized by: Its components by mass percentage include: BTA@ZIF-8 / CNTs composite material 0.25%~1%, zinc powder 49~49.75%, epoxy resin 37.5%, and curing agent 12.5%; The preparation method of the BTA@ZIF-8 / CNTs composite material comprises the following steps: Hydroxylated carbon nanotubes and benzotriazole dispersion, zinc nitrate hexahydrate solution and 2-methylimidazole solution were prepared; the hydroxylated carbon nanotubes and benzotriazole dispersion was added to the zinc nitrate hexahydrate solution, stirred for 20-30 minutes, and then the 2-methylimidazole solution was slowly added and allowed to react for 20-26 hours; after the reaction was completed, the solid product was collected by centrifugation, washed, and dried for 20-24 hours to obtain the BTA@ZIF-8 / CNTs composite material.

2. The intelligent self-healing epoxy zinc-rich coating based on MOFs material according to claim 1, characterized in that: The hydroxylated carbon nanotubes have a diameter of 10-20 nm and a length of 0.5-2 μm.

3. The intelligent self-repairing epoxy zinc-rich coating according to claim 1, characterized in that: The epoxy resin is epoxy resin E44.

4. The intelligent self-repairing epoxy zinc-rich coating according to claim 1, characterized in that: The curing agent is an epoxy curing agent.

5. The intelligent self-repairing epoxy zinc-rich coating based on MOFs material according to claim 1, characterized in that: The mass ratio of the hydroxylated carbon nanotubes, benzotriazole, zinc nitrate hexahydrate and 2-methylimidazole is 1:7:1:

22.

6. The method for preparing the intelligent self-repairing epoxy zinc-rich coating based on MOFs material according to any one of claims 1 to 5, characterized in that: The steps include: Weigh BTA@ZIF-8 / CNTs composite material, zinc powder, epoxy resin and curing agent; The BTA@ZIF-8 / CNTs composite material was added to a mixed solvent, and after ultrasonic dispersion, zinc powder and epoxy resin were added in sequence to obtain a premix component A; The curing agent is used as component B; Mix component A and component B, and stir ultrasonically for 10 to 20 minutes to obtain a uniform coating slurry; The obtained coating slurry is applied to the surface of the metal substrate, first cured at room temperature for 10 to 12 hours, then continuously thermally cured at 60 to 80°C for 4 to 8 hours, and naturally cooled in the furnace to obtain an intelligent self-healing epoxy zinc-rich coating based on MOFs material.

7. The method for preparing the intelligent self-repairing epoxy zinc-rich coating based on MOFs material according to claim 6, characterized in that: The mixed solvent is prepared by mixing xylene and n-butanol in a volume ratio of 1.5-2.0:

1.

8. The method for preparing the intelligent self-repairing epoxy zinc-rich coating based on MOFs material according to claim 6, characterized in that: The coating includes spraying or brushing.

Images