Epoxy anticorrosive paint as well as preparation method and application thereof

Abstract

The invention relates to the technical field of epoxy resin coatings, and particularly discloses an epoxy anticorrosive coating as well as a preparation method and application thereof. The anticorrosive paint comprises a component A and a component B, wherein the component A comprises the following components in parts by mass: 30-50 parts of epoxy resin, 0-10 parts of a nanoflower zinc phosphate filler loaded with a corrosion inhibitor, 25-40 parts of zinc powder, 0.5-3 parts of a defoaming agent, 0.5-3 parts of a dispersing agent and 4-10 parts of a toughening agent; 6-15 parts of a diluent; wherein the corrosion inhibitor-loaded nanoflower zinc phosphate filler is obtained by mixing phosphate, zinc salt, a corrosion inhibitor and a surfactant and carrying out hydrothermal reaction; and the component B comprises the following components in parts by mass: 5-20 parts of an epoxy curing agent and 5-15 parts of a diluent. The coating has effective barrier protection on a base material in the early stage of coating corrosion, phosphate radicals slowly released by zinc phosphate and an anchored and loaded corrosion inhibitor generate a compact protective film in a defect area in the middle and later stages, and therefore the long-term corrosion resistance and the self-repairing capacity of the coating are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of epoxy resin coatings, and particularly relates to an epoxy anticorrosive coating as well as a preparation method and application thereof. BACKGROUND

[0002] Corrosion is widespread in various industrial environments, and is one of the main factors leading to the degradation of the performance of metal materials and the failure of structures, resulting in a large amount of resource waste and serious economic losses. Among numerous corrosion protection methods, coating technology is widely used to protect metal materials from corrosion as a simple and cost-effective solution. Among them, epoxy resin coating has become a widely used protective coating due to its excellent mechanical properties, thermal stability, strong adhesion to metal and other advantages. However, the organic solvent contained in the epoxy coating will form microporous defects during the curing process, thereby accelerating the penetration of the corrosion medium into the coating and leading to the reduction of the anticorrosive performance of the coating.

[0003] In view of the problem of poor barrier performance and long-term corrosion resistance of pure epoxy coating due to micropores, modifying the epoxy anticorrosive coating with corrosion inhibitors and nano fillers is an effective method. The addition of nano fillers to the coating can fill the micropores generated during the curing process of the coating, making the coating more dense and reducing the penetration of the corrosion medium; and the corrosion inhibitor can further improve the long-term corrosion protection of the coating. Among them, loading the corrosion inhibitor in the micro / nano structure to achieve slow release has become a research hotspot. However, the existing microcontainers such as silica or polymer capsules have certain encapsulation performance, but their synthesis route is complex, involving multiple processes such as template preparation, etching treatment, loading and modification, and the process cost is high, which is not conducive to large-scale application. Therefore, developing a nano functional filler loaded with corrosion inhibitors with stable structure, high loading efficiency and simple preparation process is an effective measure. SUMMARY

[0004] The present application aims to provide an epoxy anticorrosive coating, a preparation method and application thereof, which solves the problem of invalidation of corrosion inhibitors due to rapid release in conventional fillers, avoids the complex process of preparing corrosion inhibitor containers or microcapsules in multiple steps, and further realizes the sustained release of corrosion inhibitors, improves the corrosion protection ability of the coating and prolongs its service life in industrial environments.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: The first aspect of the present application is to provide an epoxy anticorrosive coating, comprising component A and component B. The A component includes, in parts by mass, an epoxy resin 30-50 parts, a corrosion inhibitor loaded nanoflower zinc phosphate filler 0-10 parts, zinc powder 25-40 parts, a defoaming agent 0.5-3 parts, a dispersing agent 0.5-3 parts, a toughening agent 4-10 parts; The method for preparing the corrosion inhibitor loaded nanoflower zinc phosphate includes mixing soluble phosphate, zinc nitrate and corrosion inhibitor in deionized water, adding a surfactant and then performing hydrothermal reaction to obtain the corrosion inhibitor loaded nanoflower zinc phosphate filler; the corrosion inhibitor includes at least one of 8-hydroxyquinoline, benzotriazole, 1-methylimidazole, methylbenzotriazole and benzopyrazole; The B component includes, in parts by mass, an epoxy curing agent 5-20 parts, a diluent 5-15 parts.

[0006] Further, the mass ratio of the phosphate, zinc nitrate, corrosion inhibitor and surfactant is 4-5 g: 3-4 g: 0.5-3 g: 0.5-2 g.

[0007] Further, the phosphate includes at least one of sodium phosphate, ammonium phosphate and sodium phosphate.

[0008] Further, the surfactant is at least one of urea, cetyltrimethylammonium bromide, polyethylene glycol and dodecyltrimethylammonium bromide.

[0009] Further, the hydrothermal reaction is performed at 130-180℃ for 5-10 h.

[0010] Further, the epoxy resin is bisphenol A type epoxy resin or bisphenol F type epoxy resin; the bisphenol A type epoxy resin is, for example, E-44, E-51, E-54; the bisphenol F type epoxy resin is, for example, Epon 862, Epon 863.

[0011] Further, the dispersing agent is at least one of high molecular weight acrylic copolymer, polyurethane copolymer and polycarboxylate.

[0012] Further, the defoaming agent is polyether modified siloxane.

[0013] Further, the toughening agent is polyethylene glycol diglycidyl ether and / or polypropylene glycol diglycidyl ether.

[0014] Further, the diluent is xylene.

[0015] Further, the epoxy curing agent is at least one of polyamide, aliphatic amine and phenolic amine.

[0016] Further, the B component further includes, in parts by mass, an anti-flash rust agent 0-2 parts.

[0017] The second aspect of the present application is to provide a preparation method of an epoxy anticorrosive coating, wherein zinc powder, a dispersing agent and a defoaming agent are added into an epoxy resin for mixing and grinding, then a nano-flower zinc phosphate loaded with an inhibitor is added for further grinding, and then the coating is mixed and stirred uniformly by a centrifugal stirrer, and after sieving, a component A is obtained; raw materials of a component B are mixed to obtain the component B; the component A and the component B are mixed uniformly, and after sieving, the prepared coating is obtained.

[0018] Further, the sieving uses a 80-120 mesh sieve.

[0019] The third aspect of the present application is to provide the application of the above-mentioned epoxy anticorrosive coating in metal corrosion protection.

[0020] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects: (1) The epoxy anticorrosive coating provided by the present application is prepared by mixing phosphate and zinc salt with an inhibitor and a surfactant, and then obtaining a nano-flower zinc phosphate filler loaded with the inhibitor through a hydrothermal reaction. The surfactant added in the preparation process plays the role of a template agent and a pore-forming agent, which is beneficial to control the generation of nanosheets and promote the zinc phosphate to precipitate and form a porous structure. Compared with normal temperature conditions, the hydrothermal method can improve the reaction rate and make the reaction more complete, thereby promoting the formation of more nano-flowers and nucleation centers. The prepared nano-flower zinc phosphate has a higher specific surface area and more hierarchical pores than the sheet structure. On the one hand, the large surface area of the filler enables the epoxy / amine cured product to form a strong interfacial bond on the particle surface and the pore wall, effectively improving the diffusion tortuosity of the coating, reducing the water and chloride ion permeation rate, and providing active sites for the conversion film of the phosphate; on the other hand, the porous structure can provide more loading coordination sites for the inhibitor, so that the inhibitor can be released on demand under the corrosion stimulus of pH / Cl - , and the inhibitor and the phosphate / zinc ion cooperate to generate an insoluble protective film in the defect area, thereby reducing the corrosion current and improving the charge transfer resistance. As a result, the adhesion, shielding property and long-term corrosion resistance of the coating are effectively improved. In addition, the introduction of zinc-rich in the nano-flower zinc phosphate epoxy coating can realize multi-mechanism synergistic protection during the entire service process. In the early stage, the zinc powder implements cathodic protection for the metal substrate, and the free zinc ions generated after corrosion resistance can inhibit and reduce the consumption of zinc in the nano-zinc phosphate to a certain extent; in the middle and late stages, the phosphate released slowly by the zinc phosphate and the inhibitor anchored and loaded can generate a dense protective film in the defect area, which cooperates with the zinc corrosion product to seal the micro-defects and delays the self-corrosion rate of the zinc powder. The combination of the two not only prolongs the effective time of cathodic protection, but also provides chemical film protection when the protection potential is insufficient, thereby effectively improving the long-term corrosion resistance and self-repairing ability of the coating.

[0021] (2) The inhibitor 8-hydroxyquinoline provided by the present application is successfully loaded on the surface of zinc phosphate through chemical coordination, and can form a complex with Zn 2+ , PO43- The complexation promotes secondary passivation of the phosphate complex film, cooperatively builds a composite anticorrosion system of "physical barrier + chemical passivation", blocks medium penetration, inhibits metal dissolution and self-repairs defects at each stage of corrosion, and has more advantages in improving anticorrosion performance and prolonging service life than conventional zinc-rich or zinc phosphate epoxy fillers.

[0022] (3) The application provides a simple preparation method of the nano-flower zinc phosphate filler loaded with corrosion inhibitors.

[0023] (4) The zinc-rich epoxy anticorrosive coating containing the nano-flower zinc phosphate loaded with corrosion inhibitors has active and passive synergistic protection effects of barrier, adsorption and repair, plays a barrier protection role on the base material at the initial stage of coating corrosion, and plays the functions of adsorption and repair when corrosion further develops, so that the service cycle of the anticorrosive coating is effectively prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The scanning electron microscope images of the nano-flower zinc phosphate loaded with corrosion inhibitors prepared in Example 1 of the application are 5 μm and 1 μm respectively; Figure 2 The Fourier infrared spectrograms of two groups of zinc phosphates prepared in Example 1 and Comparative Example 2 of the application are shown in the figure; Figure 3 The thermogravimetric analysis curve of the nano-flower zinc phosphate not loaded with corrosion inhibitors prepared in Comparative Example 2 of the application is shown in the figure; Figure 4 The thermogravimetric analysis curve of the nano-flower zinc phosphate loaded with corrosion inhibitors prepared in Example 1 of the application is shown in the figure; Figure 5 The electrochemical impedance curve of the zinc-rich epoxy coating prepared in Comparative Example 1 of the application is shown in the figure; Figure 6 The electrochemical impedance curve of the zinc-rich epoxy coating containing 1% ZnP-NF prepared in Comparative Example 2 of the application is shown in the figure; Figure 7 The electrochemical impedance curve of the zinc-rich epoxy anticorrosive coating containing 1% ZnP-NF@8-HQ prepared in Example 1 of the application is shown in the figure; Figure 8 The electrochemical impedance curve of the zinc-rich epoxy anticorrosive coating containing 3% ZnP-NF@8-HQ prepared in Example 2 of the application is shown in the figure; Figure 9 The electrochemical impedance curve of the zinc-rich epoxy anticorrosive coating containing 5% ZnP-NF@8-HQ prepared in Example 3 of the application is shown in the figure; Figure 10The electrochemical impedance curve of the zinc-rich epoxy coating prepared for the inventive comparative example 1 after immersion in 3.5% NaCl solution for 1, 3, 7 days; Figure 11 The electrochemical impedance curve of the zinc-rich epoxy coating containing 3% ZnP-NF@8-HQ prepared for the inventive example 2 after immersion in 3.5% NaCl solution for 1, 3, 7 days; Figure 12 The photo graph of the zinc-rich epoxy coating prepared for the inventive comparative example 1 after 30-day salt spray test; Figure 13 The photo graph of the zinc-rich epoxy coating containing 1% ZnP-NF prepared for the inventive comparative example 2 after 30-day salt spray test; Figure 14 The photo graph of the zinc-rich epoxy coating containing 1% ZnP-NF@8-HQ prepared for the inventive example 1 after 30-day salt spray test; Figure 15 The photo graph of the zinc-rich epoxy coating containing 3% ZnP-NF@8-HQ prepared for the inventive example 2 after 30-day salt spray test; Figure 16 The photo graph of the zinc-rich epoxy coating containing 5% ZnP-NF@8-HQ prepared for the inventive example 3 after 30-day salt spray test. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application more clear, the specific embodiments of the present application are further described in detail below with reference to the drawings. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained in the market.

[0026] The present application provides a zinc-rich epoxy anticorrosive coating containing inhibitor-loaded nanoflower zinc phosphate, which comprises component A and component B; The component A comprises, in parts by mass, 30-50 parts of epoxy resin, 0-10 parts of inhibitor-loaded nanoflower zinc phosphate filler, 25-40 parts of zinc powder, 0.5-3 parts of defoaming agent, 0.5-3 parts of dispersing agent and 4-10 parts of toughening agent; The preparation method of the inhibitor-loaded nanoflower zinc phosphate comprises mixing soluble phosphate and zinc nitrate with an inhibitor in deionized water, and adding an appropriate amount of surfactant to perform hydrothermal reaction, so as to obtain the inhibitor-loaded nanoflower zinc phosphate filler; the inhibitor comprises at least one of 8-hydroxyquinoline, benzotriazole, 1-methylimidazole, methylbenzotriazole and benzopyrazole; The B component includes 5-20 parts by mass of an epoxy curing agent, and 5-15 parts by mass of a diluent.

[0027] In some embodiments, the mass ratio of the phosphate, zinc nitrate, corrosion inhibitor and surfactant used in the preparation of the corrosion inhibitor-loaded nanoflower zinc phosphate is 4-5 g: 3-4 g: 0.5-3 g: 0.5-2 g.

[0028] In some embodiments, the phosphate includes at least one of sodium dihydrogen phosphate, ammonium phosphate and sodium phosphate; the corrosion inhibitor includes at least one of 8-hydroxyquinoline, benzotriazole, 1-methylimidazole, methylbenzotriazole and benzopyrazole; and the surfactant is at least one of urea, cetyltrimethylammonium, polyethylene glycol and dodecyltrimethylammonium bromide.

[0029] In some embodiments, the conditions for the hydrothermal reaction of the phosphate, zinc nitrate, corrosion inhibitor and surfactant are 130-180℃ for 5-10 h, preferably 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃.

[0030] In some embodiments, the epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin; the bisphenol A type epoxy resin is, for example, E-44, E-51, E-54; the bisphenol F type epoxy resin is, for example, Epon 862, Epon 863; the dispersant is a high molecular epoxy dispersant K-019; the defoaming agent is an epoxy resin defoaming agent DF-035; the toughening agent is polypropylene glycol diglycidyl ether; the diluent is xylene; and the epoxy curing agent is at least one of a polyamide, an aliphatic amine and a phenolic amine.

[0031] In some embodiments, 906 anti-flash rust agent in an amount of 0-2 parts by mass can also be included.

[0032] The above zinc powder, dispersant and defoaming agent are added to the epoxy resin and mixed and ground, followed by the addition of the corrosion inhibitor-loaded nanoflower zinc phosphate and further grinding, and then the paint is mixed and stirred uniformly by a centrifugal stirrer, and sieved to obtain the A component; the raw materials of the B component are mixed to obtain the B component; the A component and the B component are thoroughly mixed and uniformly sieved to obtain the prepared zinc-rich epoxy anticorrosive paint containing the corrosion inhibitor-loaded nanoflower zinc phosphate.

[0033] The method provided by the application mixes phosphate and zinc salt with corrosion inhibitor and surfactant, and obtains zinc phosphate filler loaded with corrosion inhibitor through hydrothermal reaction. The main basis is to make zinc salt and phosphate and other precursors react in aqueous solution at high temperature and high pressure, and generate porous zinc phosphate nanosheet through controlling reaction conditions. The prepared zinc phosphate nanoflower has higher specific surface area and more hierarchical pores than the sheet structure. On the one hand, the large surface area of the filler enables the epoxy / amine curing product to form strong interfacial bonding on the particle surface and the pore wall, effectively improves the diffusion tortuosity of the coating, reduces the moisture and chloride ion permeation rate, and provides active sites for phosphate conversion film; on the other hand, the porous structure can provide more loading coordination sites for the corrosion inhibitor, so that the corrosion inhibitor can be released on demand under the corrosion stimulation of pH / Cl - The corrosion inhibitor and phosphate / zinc ion synergistically generate an insoluble protective film in the defect area, reduce the corrosion current, and improve the charge transfer resistance. The method provided by the application can prepare epoxy anticorrosive coatings with similar micro-morphology and performance characteristics. The prepared porous zinc phosphate nanoflower is used as a functional carrier, loaded with corrosion inhibitor, and compounded with a zinc-rich epoxy resin matrix to construct a new type of anticorrosive coating with slow-release performance and cathodic protection synergistic effect, which is expected to have good engineering adaptability and application prospect.

[0034] During the development or use of the embodiments of the application, some positive effects have been achieved, and the application indeed has great advantages compared with the prior art. The following content is described in combination with data and charts in the test process.

[0035] In the embodiments of the application, the "zinc phosphate nanoflower" refers to a hierarchical pore zinc phosphate nanoflower filler obtained through a hydrothermal method, and is abbreviated as ZnP-NF; the "ZnP-NF loaded with corrosion inhibitor" is denoted as ZnP-NF@8-HQ (when the corrosion inhibitor is 8-hydroxyquinoline).

[0036] Embodiment 1 The embodiment provides a zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with corrosion inhibitor and a preparation method, and the specific steps are as follows: (1) According to the formula proportion, 36 parts of zinc powder, 2 parts of defoaming agent, 2 parts of dispersing agent, 5 parts of toughening agent, 9 parts of diluent are added into 36 parts of E-51 bisphenol A epoxy resin, the rotation speed is controlled at 2000±500 r / min, and the mixture is ground for 2 h, then 1 part of zinc phosphate nanoflower loaded with corrosion inhibitor (1% ZnP-NF@8-HQ) is added and dispersed for 30 min, wherein the defoaming agent is added twice, and after filtering through a 100-mesh screen, the A component of the zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with corrosion inhibitor is packaged; (2) 10 parts of epoxy curing agent and 2 parts of anti-flash rust agent are stirred and mixed to obtain the B component of the zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with corrosion inhibitor. (3) Mix the A component and the B component uniformly, and coat on the surface of the Q235 steel cut sample, the coating thickness is 100±5 μm, and the normal temperature curing is 48 h.

[0037] The preparation method of the zinc phosphate nanoflower filler loaded with the corrosion inhibitor is as follows: 4.46 g of zinc nitrate hexahydrate, 3.58 g of disodium hydrogen phosphate dodecahydrate, and appropriate deionized water are mixed and stirred uniformly in a beaker, 2.4 g of urea and 0.8 g of 8-hydroxyquinoline are added, the beaker is placed in an ultrasonic machine, and the mixture is stirred again uniformly, then transferred to a polytetrafluoroethylene reaction kettle, and reacted at 150℃ for 8 h, and the insoluble substance is collected, washed, and dried to obtain the zinc phosphate nanoflower filler loaded with the corrosion inhibitor.

[0038] Example 2 The embodiment provides a zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with a corrosion inhibitor and a preparation method, and the specific steps are as follows: (1) According to the formula proportion, 34 parts of zinc powder, 2 parts of defoaming agent, 2 parts of dispersing agent, 6 parts of toughening agent, 9 parts of diluent, 34 parts of E-51 bisphenol A epoxy resin are added, the rotation speed is controlled at 2000±500 r / min, and mixing and grinding are performed for 2 h, then 3 parts of zinc phosphate nanoflower loaded with a corrosion inhibitor (3% ZnP-NF@8-HQ) are added and dispersed for 30 min, wherein the defoaming agent is added twice, filtered by using a 100 mesh screen, and packaged to obtain the A component of the zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with a corrosion inhibitor; (2) The A component and the B component are mixed uniformly, and coated on the surface of the Q235 steel cut sample, the coating thickness is 100±5 μm, and the normal temperature curing is 48 h. (3) Mix the A component and the B component uniformly, and coat on the surface of the Q235 steel cut sample, the coating thickness is 100±5 μm, and the normal temperature curing is 48 h.

[0039] The zinc phosphate nanoflower filler loaded with a corrosion inhibitor is the same as in example 1.

[0040] Example 3 The embodiment provides a zinc-rich epoxy anticorrosive coating containing zinc phosphate nanoflower loaded with a corrosion inhibitor and a preparation method, and the specific steps are as follows: (1) According to the formula proportion, 32 parts of zinc powder, 2 parts of defoaming agent, 2 parts of dispersing agent, 7 parts of toughening agent, 10 parts of diluent are added into 32 parts of E-51 bisphenol A epoxy resin, the rotating speed is controlled at 2000±500 r / min, and mixed grinding is carried out for 2 hours, then 5 parts of nano flower zinc phosphate filler loaded with corrosion inhibitor (5% ZnP-NF@8-HQ) is added and dispersed for 30 minutes, wherein the defoaming agent is added twice, and after filtering with a 100-mesh screen, the A component of the zinc-rich epoxy anticorrosive coating containing the nano flower zinc phosphate filler loaded with corrosion inhibitor is packaged; (2) 8 parts of epoxy curing agent and 2 parts of anti-flash rust agent are stirred and mixed to obtain the B component of the zinc-rich epoxy anticorrosive coating containing the nano flower zinc phosphate filler loaded with corrosion inhibitor; (3) The A component and the B component are uniformly mixed, and coating is performed on the surface of a Q235 steel cut piece, the coating thickness is 100±5 μm, and normal temperature curing is performed for 48 hours.

[0041] The nano flower zinc phosphate filler loaded with corrosion inhibitor is the same as in Example 1.

[0042] Comparative Example 1 The present comparative example provides an anticorrosive coating containing only Zn powder.

[0043] (1) According to the formula proportion, 36 parts of zinc powder, 1 part of defoaming agent, 1 part of dispersing agent, 4 parts of toughening agent, and 10 parts of diluent are added into 38 parts of E-51 bisphenol A epoxy resin, the rotating speed is controlled at 2000±500 r / min, and mixed grinding is carried out for 2 hours, wherein the defoaming agent is added twice, and after filtering with a 100-mesh screen, the A component of the zinc-rich anticorrosive epoxy coating without zinc phosphate is packaged; (2) 8 parts of epoxy curing agent and 2 parts of anti-flash rust agent are stirred and mixed to obtain the B component of the zinc-rich anticorrosive epoxy coating without zinc phosphate; (3) The A component and the B component are uniformly mixed, and coating is performed on the surface of a Q235 steel cut piece, the coating thickness is 100±5 μm, and normal temperature curing is performed for 48 hours.

[0044] Comparative Example 2 The present comparative example provides an anticorrosive coating containing a nano flower zinc phosphate filler without loaded corrosion inhibitor.

[0045] (1) According to the formula proportion, 36 parts of zinc powder, 2 parts of defoaming agent, 2 parts of dispersing agent, 5 parts of toughening agent, and 9 parts of diluent are added into 36 parts of E-51 bisphenol A epoxy resin, the rotating speed is controlled at 2000±500 r / min, and mixed grinding is carried out for 2 hours, then 1 part of nano flower zinc phosphate filler without loaded corrosion inhibitor (ZnP-NF) is added and dispersed for 30 minutes, wherein the defoaming agent is added twice, and after filtering with a 100-mesh screen, the A component of the zinc-rich epoxy anticorrosive coating containing the zinc phosphate filler without loaded corrosion inhibitor is packaged; (2) 10 parts of the epoxy curing agent, 2 parts of the anti-flash rust agent are stirred and mixed to obtain a B component of the zinc-rich epoxy anti-corrosion coating without the loaded corrosion inhibitor zinc phosphate filler; (3) The A component and the B component are uniformly mixed, and are coated on the surface of a Q235 steel cut piece at a coating thickness of 100 ± 5 μm, and are cured at room temperature for 48 h.

[0046] The preparation method of the nano-flower zinc phosphate filler without the loaded corrosion inhibitor is as follows: 4.46 g of zinc nitrate hexahydrate, 3.58 g of disodium hydrogen phosphate dodecahydrate and a proper amount of deionized water are mixed and stirred uniformly in a beaker, 2.4 g of urea is added, the beaker is placed in an ultrasonic machine to stir the mixture again, and then the mixture is transferred to a polytetrafluoroethylene reaction kettle, and is reacted at 150 ℃ for 8 h; after the reaction is completed, the insoluble substance is collected, washed and dried to obtain the nano-flower zinc phosphate filler without the loaded corrosion inhibitor.

[0047] Test example The nano-flower zinc phosphate filler with the loaded corrosion inhibitor prepared in the embodiment 1 of the present application is observed by a scanning electron microscope to obtain the SEM graph as shown in Figure 1 , which shows the successful preparation of the nano-flower zinc phosphate, and the porous structure on the surface of the nano-flower zinc phosphate provides a loading space for the corrosion inhibitor, and the hierarchical three-dimensional flower-like structure increases the surface area and improves the diffusion tortuosity of the coating.

[0048] The nano-flower porous zinc phosphate fillers with and without the loaded corrosion inhibitor prepared in the embodiment 1 and the comparative example 2 of the present application are respectively detected by a Fourier infrared spectrum to obtain the analysis curves as shown in Figure 2 . The difference between the infrared spectrum of the zinc phosphate with the loaded 8-hydroxyquinoline (ZnP-NF@8-HQ) and the pure zinc phosphate (ZnP) reflects the successful loading of the 8-hydroxyquinoline. In the infrared spectrum of the pure zinc phosphate, there is a clear O-H stretching vibration peak at about 3338 cm -1 , and the characteristic absorption peaks of the zinc phosphate can be seen at 1000 cm -1 . Compared with the pure zinc phosphate, the zinc phosphate sample with the loaded 8-hydroxyquinoline shows new absorption peaks at the same wave band, especially at 1576 cm -1 , 1500 cm -1 and 1382 cm -1 ; the 1576 cm -1 (νC=N) red shifts and the intensity decreases, the 1500 cm -1 (ring skeleton νC=C / νC=N) peak shape changes, and the 1382 cm -1 (δO-H / νC-O) weakens and is accompanied by the upward shift of the C-O band, which indicates that the 8-hydroxyquinoline is deprotonated on the surface of the ZnP-NF, and is coordinated with Zn 2+Chelating coordination is formed, achieving chemical anchoring. Furthermore, the loaded sample is at 3338 cm⁻¹. -1 The OH stretching vibration peak at the [specific location] underwent a blue shift, and the absorption intensity increased, indicating that 8-hydroxyquinoline chemically bonds to the zinc phosphate surface through its functional groups. These results strongly suggest that 8-hydroxyquinoline was successfully loaded onto the zinc phosphate surface via chemical coordination. Thermogravimetric analysis (TGA) was performed on the nano-flower porous zinc phosphate fillers prepared in Example 1 and Comparative Example 2 of this invention, with and without corrosion inhibitors, under an anaerobic environment, yielding [results]. Figure 3 and Figure 4 The analysis curves show that, under the same test conditions, the heat loss rate of the unloaded zinc phosphate nanoflowers is approximately 19.40%, while that of the loaded zinc phosphate nanoflowers is approximately 29.08%. The sharp increase in heat loss rate is attributed to the decomposition of the 8-hydroxyquinoline corrosion inhibitor loaded on the zinc phosphate nanoflowers, which also reflects that the content of 8-hydroxyquinoline loaded in the porous zinc phosphate filler with the loaded corrosion inhibitor in Example 1 of this invention is approximately 10%.

[0049] The coatings prepared in Examples 1-3 and Comparative Examples 1-2 of this invention were respectively coated onto the surface of Q235 steel sheets to form coatings, and samples were prepared for electrochemical impedance spectroscopy experiments to obtain... Figures 5-9 The analysis curves were obtained. Electrochemical impedance spectroscopy results showed significant differences in the characteristics of each group of samples on the Nyquist plot and Bode amplitude plot, reflecting the different corrosion resistance properties of the coatings. In Example 2, the Nyquist curve with the 3% ZnP-NF@8-HQ coating had the largest semicircle diameter and the real impedance reached 1.5 × 10⁻⁶. 8 Ω·cm 2 The magnitude is approximately 1.49 × 10⁻⁶ for low frequencies (0.01 Hz). 8 Ω·cm 2 Furthermore, the impedance change is gradual as the frequency decreases, indicating that the coating is dense and stable, with high polarization resistance, effectively suppressing interfacial corrosion reactions and exhibiting optimal corrosion resistance. In Example 1, the semi-circular diameter of the coating with 1% ZnP-NF@8-HQ added is slightly smaller than that of 3% ZnP-NF@8-HQ, and the low-frequency |Z| is approximately 2.15 × 10⁻⁶. 7 Ω·cm 2 It exhibits good barrier properties and interfacial stability, but is slightly inferior overall to 3% ZnP-NF@8-HQ. In Example 3, the semi-circle diameter of the coating with 5% ZnP-NF@8-HQ was significantly reduced, with a low-frequency |Z| of only 1.47 × 10⁻⁶. 5 Ω·cm 2, it is speculated that the corrosion resistance is reduced due to uneven distribution of the coating, the presence of pores or structural defects in the coating, and the easier penetration of corrosive media. In Comparative Example 2, the sample with 1% content of non-supported corrosion inhibitor zinc phosphate (denoted as 1% ZnP) has a low-frequency |Z| of about 3.14 x 10 4 Ω·cm 2 , the semicircle is small and has slight fluctuations, indicating that the polarization ability is limited, the barrier performance is relatively weak and unstable. In Comparative Example 1, the sample with only zinc powder coating (denoted as Zn) has the smallest semicircle, and the low-frequency |Z| is only about 4.16 x 10 3 Ω·cm 2 , the coating has insufficient barrier effect, the interface corrosion rate is fast, and the corrosion resistance is the worst. Further, the coatings prepared in Example 2 and Comparative Example 1 were immersed in 3.5% NaCl solution for 1, 3, and 7 days, and then electrochemical impedance tests were performed, obtaining Figure 10 and Figure 11 curves. The Bode amplitude results show that the |Z| of Example 2 at 0.01 Hz is stable at the order of 10 8 Ω·cm 2 , and after immersion for 1-7 days, it almost remains the same order, with only a slight decrease in impedance; while the low-frequency impedance of pure Zn is only 10 3 ~10 4 Ω·cm 2 , and it deteriorates significantly from 1 day to 7 days of immersion. The difference between the two is at least 5 orders of magnitude, indicating that Example 2 has extremely high low-frequency impedance and dense shielding property. The Bode phase angle results show that the coating of Example 2 maintains a wide platform close to 90° at 0.1-10 3 Hz, showing a single time constant, near-ideal capacitive behavior, indicating that the coating and interface are complete; while the phase of pure Zn decreases rapidly and diverges with time, showing multiple time constants / diffusion control characteristics, and the coating integrity is continuously destroyed. In addition, the radius of pure Zn is small and significantly shrinks with time and appears to be trailing, indicating that the charge transfer resistance is low and continuously decreasing; the Nyquist curve radius (R ct ) of Example 2 coating is large and remains large after 7 days of immersion, indicating that the long-term corrosion inhibition effect of the coating after adding 3% ZnP-NF@8-HQ filler is also significantly better than that of the conventional pure Zn epoxy coating. In summary, the corrosion resistance of the coating from high to low is as follows: 3% ZnP-NF@8-HQ > 1% ZnP-NF@8-HQ > 5% ZnP-NF@8-HQ > 1% ZnP-NF > Zn. Among them, the addition of 3% ZnP-NF@8-HQ nanoflower filler is more helpful to the improvement of the corrosion resistance of the epoxy coating than the general filler, which is attributed to the multi-level pore structure and long path barrier provided by the nanoflower ZnP, and the slow release of the loaded 8-HQ at defects / microcracks, as well as the Zn 2+ , PO4 3-The complexation and the secondary passivation of the phosphate complex film are promoted, and a composite corrosion protection system of "physical barrier + chemical passivation" is constructed. The results are consistent with the change law of Nyquist semicircle diameter and Bode amplitude low-frequency impedance, which is consistent with the experimental prediction, and can provide a reference for coating formula optimization and protection system design.

[0050] The coatings prepared in Example 1-Example 3 and Comparative Example 1-2 are respectively coated on the surface of Q235 steel sheet to prepare a coating and subjected to a salt spray test, and the analysis curves of Figures 10-14 The 30-day neutral salt spray test results show that: the rust spreading of Example 2 (3% ZnP-NF@8-HQ) is the smallest, the corrosion is basically limited to the inside of the scratch, there is no blistering or large area of loss of luster on the surface, the edge rust penetration is the lightest, and the corrosion resistance is the best; Example 1 (1% ZnP-NF@8-HQ) only has a narrow rust line, the spreading width is slightly larger than that of Example 2, and the overall still maintains high shielding and stability; Example 3 (5% ZnP-NF@8-HQ) has a continuous brown rust liquid along the scratch, accompanied by local blistering, which may be due to the excessive filler leading to the increase of agglomeration / pores and the damage of the cathode network; Comparative Example 2 (1% ZnP-NF) has a wide rust band on both sides of the scratch, and the edge rust penetration is obvious, and the long-term protection is insufficient; Comparative Example 1 (only Zn powder) has the most significant corrosion, and the rust spreading around the scratch and the in-plane loss of luster are the most serious. According to the criteria of rust spreading width, blistering / peeling area and edge rust penetration, the 30-day coating corrosion resistance is ranked as: 3% ZnP-NF@8-HQ > 1% ZnP-NF@8-HQ > 5% ZnP-NF@8-HQ > 1% ZnP-NF > Zn; the trend is consistent with the electrochemical impedance ranking, further verifying the synergistic protection mechanism of "ZnP-NF@8-HQ slow release + zinc-rich". Therefore, the zinc-rich epoxy corrosion-resistant coating prepared by adding an appropriate amount of zinc phosphate containing loaded corrosion inhibitor nanoflower relies on the synergistic effect of physical shielding, cathodic protection and chemical film multi-mechanism to block the medium penetration, inhibit the metal dissolution and self-repair defects at each stage of corrosion, and has more advantages in improving the corrosion resistance and prolonging the service life compared with the conventional zinc-rich or zinc phosphate epoxy filler.

[0051] In the case of no conflict, the features in the above embodiments and the embodiments can be combined with each other. The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An epoxy anti-corrosion coating, characterized in that, Includes component A and component B; Component A, by weight, includes 30-50 parts epoxy resin, 0-10 parts nano-flower zinc phosphate filler loaded with corrosion inhibitor, 25-40 parts zinc powder, 0.5-3 parts defoamer, 0.5-3 parts dispersant, and 4-10 parts toughening agent. The method for preparing nano-flower zinc phosphate loaded with corrosion inhibitor includes mixing soluble phosphate and zinc nitrate with corrosion inhibitor in deionized water, adding surfactant, and then carrying out a hydrothermal reaction to obtain nano-flower zinc phosphate filler loaded with corrosion inhibitor; the corrosion inhibitor includes at least one of 8-hydroxyquinoline, benzotriazole, 1-methylimidazole, methylbenzotriazole, and benzopyrazole. Component B, by weight, comprises 5-20 parts epoxy curing agent and 5-15 parts diluent.

2. The epoxy anti-corrosion coating according to claim 1, characterized in that, The mass ratio of the phosphate, zinc nitrate, corrosion inhibitor, and surfactant is 4-5g: 3-4g: 0.5-3g: 0.5-2g.

3. The epoxy anti-corrosion coating according to claim 2, characterized in that, The phosphate includes at least one of sodium dihydrogen phosphate, ammonium phosphate, and sodium phosphate; the surfactant is at least one of urea, hexadecyltrimethylammonium bromide, polyethylene glycol, and dodecyltrimethylammonium bromide.

4. The epoxy anti-corrosion coating according to any one of claims 2-3, characterized in that, The hydrothermal reaction is carried out at 130-180℃ for 5-10 hours.

5. The epoxy anti-corrosion coating according to claim 1, characterized in that, The epoxy resin is bisphenol A type epoxy resin or bisphenol F type epoxy resin; The dispersant is at least one of the following: high molecular weight acrylic copolymer, polyurethane copolymer, and polycarboxylate. The defoamer is a polyether-modified siloxane; The toughening agent is polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether; The diluent is xylene.

6. The epoxy anti-corrosion coating according to claim 1, characterized in that, The epoxy curing agent is at least one of polyamide, fatty amine, and phenolic amine.

7. The epoxy anti-corrosion coating according to claim 1, characterized in that, Component B also includes 0-2 parts by weight of anti-flash rust agent.

8. The method for preparing the epoxy anti-corrosion coating as described in any one of claims 1-7, characterized in that, Zinc powder, dispersant, and defoamer are added to epoxy resin and mixed and ground. Then, nano-zinc phosphate loaded with corrosion inhibitor is added and ground again. The coating is then mixed and stirred evenly using a centrifugal mixer and sieved to obtain component A. The raw materials of component B are mixed to obtain component B. Component A and component B are thoroughly mixed evenly and sieved to obtain epoxy anti-corrosion coating.

9. The preparation method according to claim 8, characterized in that, The sieving process uses an 80-120 mesh sieve.

10. The application of an epoxy anti-corrosion coating as described in any one of claims 1-7 in metal corrosion protection.

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