A self-warning anti-corrosion coating, anti-corrosion coating and its application in anti-corrosion of metal materials

Abstract

The present invention provides a self-warning anti-corrosion coating, an anti-corrosion coating and their applications. The self-warning anti-corrosion coating includes a first coating and a second coating. The first coating contains modified zirconium phosphate and a coating matrix; the second coating contains silica microcapsules and a coating matrix; the modified zirconium phosphate is prepared by modifying zirconium phosphate with a modifier; the silica microcapsules are prepared by impregnating mesoporous silica with tannic acid so that the interior of the silica microcapsules is loaded with tannic acid. The present invention also provides a method for anti-corrosion treatment of metal materials using the self-warning anti-corrosion coating and a self-warning anti-corrosion coating formed on the surface of metal materials by this method. The present invention utilizes the physical barrier effect of zirconium phosphate and the passivation, corrosion inhibition and color display effects of tannic acid to achieve self-warning of corrosion and long-term protection of the coating for metal materials.

Description

Technical Field

[0001] The present invention relates to the field of multifunctional anti-corrosion coatings, and particularly to a self-warning anti-corrosion coating, an anti-corrosion coating and their applications in anti-corrosion of metal materials. Background Art

[0002] Metal corrosion is an inevitable natural chemical process. The main purpose of metal protection methods is to prevent or reduce metal corrosion.

[0003] Among many metal protection methods, anti-corrosion coatings are one of the most effective means to reduce metal corrosion. An anti-corrosion coating is a special protective layer coated on the metal surface to prevent or reduce the harmful effects of corrosion. However, micropores and defects formed during the coating curing process can lead to its lack of long-term anti-corrosion performance.

[0004] To address the problem of the lack of long-term anti-corrosion performance of anti-corrosion coating materials, a metal protection method is to introduce two-dimensional sheet materials into the anti-corrosion coating to utilize the "labyrinth effect" of the two-dimensional sheet materials to improve the shielding performance of the anti-corrosion coating.

[0005] The patent application documents with publication numbers CN116285462A, CN118048061A, and CN116948497A reported currently all involve the applications of carbon nanosheets, diamond nanosheets, and graphene two-dimensional sheet materials in anti-corrosion coatings. However, due to the anti-corrosion coatings provided by the above-reported patent applications having single functions and expensive materials, the problem of long-term anti-corrosion for large-scale applications in industrial production in different fields cannot be solved.

[0006] Another method to extend the anti-corrosion performance of the coating is to introduce a corrosion inhibitor into the coating matrix. The corrosion inhibitor can not only fill the coating pores generated due to solvent evaporation during the preparation of the anti-corrosion coating, making the anti-corrosion coating more dense, but also repair the anti-corrosion coating through the corrosion inhibitor when scratches appear on the anti-corrosion coating, thereby enhancing the anti-corrosion performance of the coating.

[0007] Zirconium phosphate (α-ZrP) is a new type of multifunctional hierarchical material developed in recent years. Due to zirconium phosphate having a high aspect ratio and a morphologically controllable molecular structure, it is often regarded as a model for studying two-dimensional sheet materials and has been widely used in fields such as lubrication and corrosion resistance. Compared with traditional two-dimensional sheet materials, zirconium phosphate exhibits better load-bearing capacity and wear resistance under higher loads. Moreover, due to the excellent thermal stability of zirconium phosphate, the long-term anti-corrosion property of the anti-corrosion coating can be maintained at high temperatures.

[0008] In addition, tannic acid (TA) is introduced into the anti-corrosion coating as a corrosion inhibitor and a corrosion warning agent (corrosion probe). When microcracks appear inside the anti-corrosion coating, it can be detected and repaired in time at an early stage, which is conducive to realizing the corrosion self-warning function and long-term anti-corrosion performance of the anti-corrosion coating. However, if the corrosion inhibitor and the corrosion warning agent are directly introduced into the coating, the reagent will be prematurely released in the anti-corrosion coating. To solve this problem, the corrosion inhibitor and / or the corrosion warning agent are usually placed in a nano-container and then dispersed in the anti-corrosion coating matrix. In addition, the nano-container can effectively improve the compatibility between the anti-corrosion coating matrix and the corrosion inhibitor and / or the corrosion warning agent, extend the release time of the corrosion inhibitor, and realize the long-term protection function of the coating.

[0009] Effectively combining the barrier performance of two-dimensional sheet materials with the corrosion self-warning performance of corrosion inhibitors and through the optimized design of the coating structure has important research significance for realizing the corrosion self-warning function and long-term anti-corrosion performance of the coating. Summary of the Invention

[0010] (I) Technical Problems:

[0011] (1) The micropores and defects formed during the curing process of the existing anti-corrosion coatings will cause the infiltration of corrosive media, resulting in poor anti-corrosion performance of the anti-corrosion coatings;

[0012] (2) The long-term anti-corrosion performance of the existing anti-corrosion coatings is still not ideal;

[0013] (3) During the use of the existing anti-corrosion coatings, the specific corrosion sites inside cannot be judged;

[0014] (4) There is a lack of multifunctional coatings with corrosion warning and long-term anti-corrosion functions.

[0015] (II) Technical Solutions:

[0016] To solve the above technical problems, the present invention provides a self-warning anti-corrosion coating in the first aspect. The self-warning long-term anti-corrosion coating includes a first coating and a second coating. The first coating contains modified zirconium phosphate and a first coating matrix; the second coating contains silica microcapsules and a second coating matrix. The modified zirconium phosphate is prepared by modifying zirconium phosphate with a modifier; the silica microcapsules are prepared by impregnating mesoporous silica with tannic acid so that tannic acid is loaded inside the silica microcapsules.

[0017] The present invention provides a method for anti-corrosion treatment of metal materials in the second aspect. The method includes the step of coating the metal materials with the self-warning anti-corrosion coating described in the first aspect of the present invention.

[0018] The present invention provides a self-warning anti-corrosion coating in the third aspect, and the self-warning anti-corrosion coating is formed on the surface of a metal material by the method described in the second aspect of the present invention.

[0019] Compared with the prior art, the present invention has the following technical advantages:

[0020] (1) In the present invention, modified zirconium phosphate (a two-dimensional sheet material) and silica microcapsules loaded with tannic acid are respectively filled into a resin matrix and sprayed in layers. The upper zirconium phosphate coating uses the shielding performance of the sheet material to play a physical barrier role, so that corrosive media are effectively blocked in the initial stage of penetration. On the one hand, the silica microcapsules in the lower coating can fill the pores generated inside during the curing of the resin, making the coating more dense and making it difficult for corrosive media to penetrate; on the other hand, the tannic acid loaded by the silica microcapsules can form a passivation film with a metal material such as a steel plate through a complexation reaction, playing a corrosion inhibition role. Since tannic acid can only form a passivation film after contacting the metal substrate, the silica microcapsules loaded with tannic acid are added to the bottom layer of the coating in the layered coating structure. By utilizing the synergistic effect of zirconium phosphate and tannic acid in this way, the present invention can effectively improve the long-term anti-corrosion performance of the coating. After testing, the impedance modulus (|Z| 0.01Hz ) of the coating prepared by the present invention can still be maintained at 10 9 Ω·cm 2 or more after 100 days of immersion in brine (for example, an aqueous solution of 3.5 wt% NaCl, 25 °C), and most of them can be maintained at 10 10 Ω·cm 2 or more.

[0021] (2) In the present invention, tannic acid is impregnated (for example, by vacuum impregnation) into mesoporous silica. During the process of corrosive solution penetrating the coating, tannic acid is released from the mesoporous silica and undergoes a complexation reaction with the metal steel plate (the color can change during this reaction process). At this time, tannic acid serves as a corrosion inhibitor and a corrosion probe, and can sense the internal corrosion sites of the coating through color change, enabling the coating to have both anti-corrosion and self-warning functions.

[0022] (3) The self-warning long-term anti-corrosion coating with a layered structure prepared by the present invention can still maintain a relatively high impedance modulus under high-temperature and high-salt conditions (90 °C, 12 wt% NaCl aqueous solution, 120 hours), and has excellent anti-corrosion performance. Description of the Drawings

[0023] Figure 1 Shows a schematic diagram of the layered structure of the self-warning anti-corrosion coating of the present invention.

[0024] Figure 2 Shows an SEM image of the cross-section of the self-warning anti-corrosion coating prepared in Example 4 of the present application.

[0025] Figure 3 Shows the scratch test results carried out in Example 4, including optical photos of the pure EP scratch coating soaked in 3.5 wt% brine on the 0th day (a1) and the 10th day (a2), and optical photos of the composite coating of the layered structure of the present invention soaked in 3.5 wt% brine on the 0th day (b1) and the 10th day (b2).

[0026] The reference numerals are represented as follows: 1 represents modified zirconium phosphate; 2 represents silica microcapsules; 3 represents a color-developing (purple-black) self-warning phenomenon; 4 represents a metal material; 5 represents an upper coating; 6 represents a bottom coating. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] The present invention provides a self-warning anti-corrosion coating in a first aspect. The self-warning long-lasting anti-corrosion coating includes a first coating and a second coating. The first coating contains modified zirconium phosphate and a first coating matrix; the second coating contains silica microcapsules and a second coating matrix. The modified zirconium phosphate is prepared by modifying zirconium phosphate with a modifier; the silica microcapsules are prepared by impregnating mesoporous silica with tannic acid so that the interior of the silica microcapsules is loaded with tannic acid.

[0029] Some coating matrices may require a curing agent (for example, according to the suggestions in the instructions of commercially available coating matrices or sometimes faster curing is required). In this case, the first coating and / or the second coating may contain a curing agent in an amount required for curing. However, those skilled in the art are fully capable of selecting a suitable curing agent and its dosage after reading this application.

[0030] In some preferred implementation manners, the modifier is selected from one of 3-(trimethoxysilyl)propyl methacrylate (sometimes called KH550), 3-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

[0031] The first coating matrix and the second coating matrix may be the same or different.

[0032] Preferably, the first coating matrix and the second coating are independently resin matrices. More preferably, the first coating matrix and the second coating matrix are independently selected from at least one of epoxy resin, polyurea resin, polyurethane, etc.

[0033] In some other preferred embodiments, the modified zirconium phosphate is prepared by the following method: (i) dispersing zirconium phosphate ((α-ZrP)) in a buffer solution to obtain a zirconium phosphate dispersion; (ii) dissolving a modifier in a modifying solvent to obtain a modifier solution; (iii) adding the zirconium phosphate dispersion to the modifier solution for a modification reaction to obtain the modified zirconium phosphate.

[0034] In some other preferred embodiments, the buffer solution is a tris(hydroxymethyl)aminomethane aqueous buffer solution with a concentration of 0.01M to 0.05M (such as 0.02, 0.03 or 0.04M).

[0035] More preferably, the mass fraction of zirconium phosphate in the zirconium phosphate dispersion is 0.5% to 3% (such as 1% or 2%).

[0036] In some other preferred embodiments, the dispersion is carried out by ultrasonic dispersion. Preferably, the ultrasonic dispersion time is 20 minutes to 40 minutes (such as 30 minutes).

[0037] In some other preferred embodiments, after the dispersion, the pH of the zirconium phosphate dispersion is adjusted (such as using 1M HCl aqueous solution) to pH = 1 to 3 (such as pH = 2).

[0038] In a more specific embodiment, the modified zirconium phosphate is prepared by the following method: preparing a tris(hydroxymethyl)aminomethane (Tris) aqueous buffer solution with a concentration of 0.01M to 0.05M, adding zirconium phosphate (α-ZrP) (the mass fraction of α-ZrP in the Tris buffer solution is 0.5% to 3%), ultrasonically dispersing for 20 minutes to 40 minutes, and then slowly adding 1M HCl to adjust the pH = 1 to 3 to obtain a zirconium phosphate-tris(hydroxymethyl)aminomethane mixed solution.

[0039] In some other preferred embodiments, the modifying solvent is ethanol.

[0040] More preferably, the mass fraction of the modifier in the modifier solution is 0.25% to 1.5% (such as 0.5, 1.0 or 1.25%).

[0041] In some other preferred embodiments, during the process of dissolving the modifier in the modifying solvent, it can be heated at 50 - 70°C (such as in a water bath) for 30 to 60 minutes to achieve the dissolution.

[0042] In step (iii), the volume ratio of the zirconium phosphate dispersion to the modifier solution can be 1:1. The addition method can be dropwise addition. After addition, it can be stirred for, for example, 5 to 10 hours (stirring speed 300 - 500 rpm), and then washed, filtered by suction, and dried to obtain modified zirconium phosphate.

[0043] In a more specific embodiment, a modifier such as 3-(trimethoxysilyl)propyl methacrylate (KH550) can be dissolved in absolute ethanol (the mass fraction of KH550 is 0.25% to 1.5%). After heating in a water bath at 50 - 70 °C for 30 to 60 minutes, a modifier solution is obtained. Then, the zirconium phosphate dispersion (such as a zirconium phosphate - tris(hydroxymethyl)aminomethane mixed solution) is added dropwise to the modifier solution (the volume ratio of the two solutions can be 1:1), stirred for 5 to 10 hours, washed, filtered by suction, and dried to obtain zirconium phosphate modified with a modifier (such as KH550), that is, modified zirconium phosphate.

[0044] In some other preferred embodiments, the particle size of the mesoporous silica is 100 nm to 2 μm (for example, 400 or 500 nm).

[0045] In some other preferred embodiments, the mass ratio of tannic acid to mesoporous silica used during impregnation is 1 to 3:1 (for example, 2:1).

[0046] In some other preferred embodiments, the silica microcapsules are prepared by the following method: (I) Dispersing a template agent in a dispersion liquid for the template agent and emulsifying to obtain a template agent emulsion; (II) Adding a silica precursor to the template agent emulsion for a coating reaction to obtain silica - coated template agent microcapsules; (III) Performing a heat treatment on the silica - coated template agent microcapsules to obtain mesoporous silica; (IV) Impregnating the mesoporous silica with tannic acid to obtain silica microcapsules with tannic acid loaded inside.

[0047] In some other preferred embodiments, the template agent is cetyltrimethylammonium bromide.

[0048] In some other preferred embodiments, the dispersion liquid for the template agent is a mixed solution of ethanol and deionized water with a mass ratio of 9:1 to 1:4.

[0049] In some other preferred embodiments, the mass fraction of the template agent in the template agent emulsion is 0.3% to 2.0%.

[0050] In some other preferred embodiments, the silica precursor is tetraethyl orthosilicate.

[0051] In some other preferred embodiments, the heating temperature of the heat treatment is 400 to 800 °C, and the treatment time is 3 to 5 hours.

[0052] In some more specific embodiments, the mesoporous silica can be prepared as follows: Prepare a mixed solution of anhydrous ethanol and deionized water (the mass ratio of anhydrous ethanol to water can be 9:1 to 1:4), add cetyltrimethylammonium bromide (CTAB) with a mass fraction of 0.3% to 2.0%, and after high-speed emulsification for 5 minutes (emulsification speed 5000 to 8000 rpm), a template agent solution is obtained. Transfer the template agent solution to a three-necked flask, and add tetraethyl orthosilicate with a mass fraction of 2% to 5% respectively. Adjust the pH of the system to 10 to 12 with, for example, ammonia water, and stir in a water bath at 50 - 80 °C for 2 to 6 hours (stirring speed 500 - 800 rpm). After washing, filtering, and drying, silica microcapsules coated with the template agent are obtained. Heat the silica microcapsules coated with the template agent at 400 to 800 °C (for example, a muffle furnace can be used) for 3 to 5 hours to obtain mesoporous silica (MSN) (particle size 100 nm to 2 μm).

[0053] During impregnation, tannic acid and mesoporous silica can be mixed at a mass ratio of 1 to 3:1. Disperse the obtained mixture in anhydrous ethanol (the mass ratio of the mixture in anhydrous ethanol is 5% - 20%), and transfer it to a vacuum drying oven (it can be at 25 °C under a vacuum degree of 0.06 to 0.09). Take it out and stir evenly after 20 - 60 min, then put it back into the vacuum drying oven again, and repeat 2 to 3 times. After washing, filtering, and drying the obtained suspension, silica microcapsules internally loaded with tannic acid are obtained (sometimes referred to as TA@MSN in this article).

[0054] When necessary, the anticorrosive coating may contain an optional curing agent. The present invention places no particular limitation on the curing agent, and its type and dosage can be selected within the capabilities of those skilled in the art.

[0055] In a second aspect of the present invention, a method for anticorrosively treating a metal material is provided, and the method includes the step of coating the self-warning anticorrosive coating described in the first aspect of the present invention on the metal material.

[0056] In some preferred embodiments, the coating treatment is carried out in two steps: (a) Coating the second coating on the metal material to form a bottom layer coating; (b) Coating the first coating on the bottom layer coating to form an upper layer coating, and then curing the coating.

[0057] In some embodiments, in the second coating, the amount of the silica microcapsules relative to the first coating substrate (or relative to the total mass of the first coating substrate and the curing agent if a curing agent is used) is 2% to 20% by mass (such as 5%, 10% or 15% by mass), preferably 5% to 15% by mass. After the silica microcapsules are added to the coating substrate and stirred evenly, it can be sprayed onto the surface of a metal material (such as a steel plate) at a temperature from room temperature to 130 °C (such as 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120 °C) and a spraying pressure of 0.6 MPa to 1.0 MPa (such as 0.7, 0.8 or 0.9 MPa) to form a bottom layer coating. Preferably, the thickness of the bottom layer coating can be 30 μm to 100 μm, such as 50, 60, 70, 80 or 90 μm.

[0058] After the bottom layer coating is formed, an upper layer coating is then formed on the bottom layer coating. In some embodiments, in the first coating, the amount of the modified zirconium phosphate relative to the second coating substrate (or relative to the total mass of the second coating substrate and the curing agent if a curing agent is used) is 5% to 40% by mass (such as 10%, 20% or 30% by mass), preferably 10% to 30% by mass, more preferably 10% to 20% by mass. After the modified zirconium phosphate is added to the coating substrate and stirred evenly, it can be sprayed onto the surface of the bottom layer coating at a temperature from room temperature to 130 °C (such as 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120 °C) and a spraying pressure of 0.6 MPa to 1.0 MPa (such as 0.7, 0.8 or 0.9 MPa) to form an upper layer coating. Preferably, the thickness of the upper layer coating can be 60 μm to 200 μm, such as 80, 100, 120, 140, 160 or 180 μm.

[0059] Thus, the total thickness of the anti-corrosion coating prepared by the method of the present invention can be 100 μm to 300 μm, such as 200 μm.

[0060] For the convenience of coating, some types of epoxy resin need to be appropriately diluted with a diluent (such as ethyl acetate) when used as a coating substrate to facilitate spraying, while some coating substrates such as waterborne polyurethane do not need to be diluted with a diluent. The specific degree of dilution is completely within the ability range of those skilled in the art after reading this specification.

[0061] In some preferred embodiments, the curing of the bottom layer coating and the upper layer coating can be independently cured at room temperature for 12 hours to 4 hours (such as 15, 18, or 21 hours), and then cured at 40°C to 100°C (such as 50 or 80°C) for 3 hours to 6 hours (4 or 5 hours). Finally, a self-warning long-term anti-corrosion coating with a layered structure is prepared, and the coating thickness is 100 - 300 μm.

[0062] The metal material can be iron material (such as steel pipe material or steel plate material or other profiles), aluminum material, copper material, etc. When the metal material is steel plate material, the model of the steel plate material can be one of the models such as Q195, Q235, Q345, etc.

[0063] Before coating, the metal material such as steel plate material can be ground, polished, and rinsed first. Grinding can be carried out using sandpaper. The selected sandpaper can be 600-mesh, 800-mesh, or 1000-mesh sandpaper. The solvent used for rinsing can be at least one of ethanol, acetone, ethyl acetate, etc.

[0064] In some embodiments, the coating is carried out by spraying. For example, the spraying can be carried out when the temperature of the metal material is maintained at 80°C to 130°C (such as 90, 100, 110, or 120°C), and the spraying pressure can be 0.6 MPa to 1.0 MPa.

[0065] The present invention provides a self-warning anti-corrosion coating in the third aspect, and the self-warning anti-corrosion coating is formed on the surface of the metal material by the method described in the second aspect of the present invention.

[0066] Figure 1 Shows a schematic diagram of the layered structure of the self-warning anti-corrosion coating of the present invention. As Figure 1 shown, the anti-corrosion behavior of the upper zirconium phosphate layer is mainly reflected in the initial stage of soaking, and the physical shielding effect effectively prevents the penetration of corrosive media; in addition, if the corrosive media penetrate the zirconium phosphate layer during long-term soaking, the anti-corrosion behavior of the coating is mainly reflected by the bottom silica microcapsule layer. Tannic acid, as a corrosion inhibitor and corrosion probe, is released from the silica microcapsules during soaking and adsorbed on the surface of the metal steel plate to form an adsorption layer (passivation film). On the one hand, this adsorption layer can further prevent the penetration of corrosive media and play an anti-corrosion role; on the other hand, a color change will occur during the formation of the adsorption layer, changing from light yellow to purple-black, which can realize early warning of the corrosion condition inside the coating, accurately judge the corrosion site, and perform repair. The present invention prepares a long-term anti-corrosion coating with a simple process and dual functions of self-warning and self-repair.

[0067] The filler composition of the present invention can be used to form a layered structure of an anticorrosive coating on a metal material, using the physical shielding effect of the zirconium phosphate layer to achieve early anticorrosion, while using the later repair effect of the underlying silica microcapsule layer to achieve synergistic anticorrosion, so that the coating has long-term anticorrosion performance. In addition, the coating of the present invention can accurately determine the internal corrosion site of the coating through color changes, so that it can be repaired in time.

[0068] Example

[0069] Preparation Example 1: Preparation of modified zirconium phosphate

[0070] This step provides for modifying zirconium phosphate using a modifier, and the specific method is as follows:

[0071] Prepare 100 mL of tris (hydroxymethylaminomethane) (Tris) aqueous buffer solution with a concentration of 0.02 M, add 1 g of zirconium phosphate (α-ZrP), ultrasonically disperse for 20 minutes, and then add 1 M HCl to adjust the pH to 2 to obtain a zirconium phosphate-tris (hydroxymethylaminomethane) mixed solution.

[0072] 0.5 g of 3-(trimethoxysilyl)propyl methacrylate (KH550) was dissolved in 100 mL of anhydrous ethanol. After heating in a water bath at 60°C for 30 minutes, a zirconium phosphate-trishydroxymethylaminomethane mixed solution was added dropwise to the solution and stirred for 8 hours. After washing, filtration and drying, KH550-modified zirconium phosphate (modified ZrP) was obtained.

[0073] Preparation Example 2: Preparation of Silica Microcapsules

[0074] First, a one-step method is used to prepare silica coated with a template, and the coated template is removed at high temperature in a muffle furnace to obtain mesoporous silica. Specifically, a mixed solution of anhydrous ethanol and distilled water with a mass ratio of 1:2 (80 ml of anhydrous ethanol and 160 ml of distilled water) is prepared, 0.8 g of hexadecyltrimethylammonium bromide (CTAB) is added, and then high-speed emulsification is performed for 5 minutes (emulsification speed 5000 rpm), and then transferred to a three-necked flask, and 3 mL of tetraethyl orthosilicate is added, and the pH is adjusted to 10 with ammonia water, and stirred in a water bath at 80°C for 3 hours (stirring speed 800 rpm), washed, filtered, and dried to obtain silica coated with a template. Finally, the silica coated with a template is heated in a muffle furnace at 600°C for 5 hours to obtain mesoporous silica (MSN) (particle size 450 nm).

[0075] The prepared mesoporous silica (MSN) was impregnated with tannic acid under vacuum to obtain silica microcapsules loaded with tannic acid inside (TA@MSN). Specifically, a mixture with a mass ratio of tannic acid to mesoporous silica of 2:1 (0.2 g of tannic acid and 0.1 g of mesoporous silica) was dissolved in 10 ml of absolute ethanol, and transferred to a vacuum drying oven (25 °C, vacuum degree 0.09). After 40 min, it was taken out and stirred evenly, then put back into the vacuum drying oven again, and this was repeated 3 times. After the obtained suspension was washed, filtered, and dried, silica microcapsules containing tannic acid inside (TA@MSN) were obtained.

[0076] Example 1: Preparation of an anti-corrosion coating for metal materials

[0077] In this example, a steel plate was used as the metal material, and a layered structure including a bottom layer coating and an upper layer coating was sequentially formed on the surface as the anti-corrosion coating.

[0078] (A) Preparation of the metal material

[0079] The steel plate was polished, buffed, and repeatedly rinsed with water and a solvent. Specifically, the Q235 steel plate was polished successively with 600-mesh and 1000-mesh sandpapers, and rinsed successively with water and absolute ethanol to remove surface stains, obtaining the steel plate to be coated.

[0080] (B) Preparation of the bottom layer coating

[0081] The silica microcapsules loaded with tannic acid were added to the coating matrix to prepare a second coating, which was then sprayed onto the surface of the steel plate to prepare the bottom layer coating.

[0082] Specifically, for comparative research, the inventor first prepared a pure resin coating without any fillers. 2.4 g of E51 epoxy resin and 0.8 g of D230 curing agent were dissolved in 10 ml of ethyl acetate, stirred to prepare a pure EP homogeneous solution, and sprayed onto the surface of the Q235 steel plate at a temperature of 100 °C and a spraying pressure of 0.6 MPa. After curing at room temperature for 12 hours, it was then cured at 60 °C for 3 h to obtain a pure EP coating with a thickness of 120 μm.

[0083] 0.9 g of E51 epoxy resin and 0.3 g of D230 curing agent were dissolved in 10 ml of ethyl acetate, and 0.12 g of TA@MSN was added and stirred evenly to obtain a second coating; it was sprayed onto the surface of the Q235 steel plate under the conditions of a temperature of 100 °C and a spraying pressure of 0.6 MPa to prepare a silica microcapsule coating as the bottom layer coating with a thickness of 40 μm.

[0084] (C) Preparation of the upper layer coating

[0085] The modified zirconium phosphate is filled into the first coating matrix to prepare the first coating, which is then sprayed onto the surface of the previously prepared bottom coating to prepare the upper coating.

[0086] Specifically, 1.5 g of E51 epoxy resin and 0.5 g of D230 curing agent are dissolved in 10 ml of ethyl acetate, and 0.40 g of modified zirconium phosphate is added. After stirring evenly, the first coating is obtained. It is sprayed onto the surface of the above-mentioned silica microcapsule coating (i.e., the bottom coating) under the conditions of a temperature of 100 °C and a spraying pressure of 0.6 MPa to prepare a zirconium phosphate coating (i.e., the upper coating) with a thickness of 80 μm.

[0087] Thus far, a layered structure including a bottom coating and an upper coating is formed on the steel plate (see Figure 2 ).

[0088] (D) Curing of the coating

[0089] The prepared composite coating is cured to obtain a composite coating with a layered structure.

[0090] Specifically, the sprayed composite coating is cured at room temperature for 12 hours and then at 60 °C for 3 hours, and finally a self-warning long-lasting layered structure anti-corrosion coating is prepared with a coating thickness of 120 μm.

[0091] After testing, the self-warning long-lasting anti-corrosion coating with a layered structure prepared in this example can detect and warn the corrosion situation of metals in a timely manner.

[0092] First, the anti-corrosion coating prepared in this example is immersed in a 3.5 wt% NaCl solution for 100 days, and |Z| 0.01Hz still remains at 10 10 Ω·cm 2 or above; after being immersed in extreme conditions of high temperature and high salt (90 °C, 12 wt% NaCl aqueous solution) for 120 hours, |Z| 0.01Hz can still reach 8.05×10 9 Ω·cm 2 .

[0093] Secondly, the prepared layered coating is scratched until it reaches the steel plate substrate to ensure that the steel plate is exposed to the corrosive environment. At the same time, for comparative research, the pure epoxy coating is also scratched. After the two scratched coatings are immersed in a 3.5 wt% NaCl aqueous solution at room temperature for 10 days, blisters appear on the surface of the pure EP coating, and the corrosion is relatively serious; while the surface of the layered structure coating of the present invention is dense, has good repair performance, and a purple-black self-warning phenomenon appears at the scratched area (see Figure 3 ). This is mainly due to the rich Fe generated by the oxidation-reduction reaction on the metal surface 3+When encountering tannic acid released from mesoporous silica, a purple-black tannic acid-Fe 3+ complex will be formed. The layered coating prepared in Example 1 exhibits excellent self-warning and long-term anti-corrosion properties.

[0094] Examples 2 to 12

[0095] Except for the content shown in Table 1 below, it is carried out in substantially the same manner as in Example 1.

[0096] Table 1. Content of modified zirconium phosphate in the first coating, content of silica microcapsules in the second coating, and anti-corrosion properties of the formed coatings in each example

[0097]

[0098] Note: Modified ZrP is the modified zirconium phosphate prepared in Preparation Example 1; TA@MSN is the silica microcapsule prepared in Preparation Example 2; the content represents the mass percentage (mass%) of modified zirconium phosphate or silica microcapsule relative to the coating matrix and curing agent (if any) in the corresponding coating.

[0099] |Z| 0.01Hz The magnitude of the value can be used as an index to evaluate the anti-corrosion performance of the coating. During the entire immersion process, the |Z| of the composite coating with a layered structure 0.01Hz remains at a quite high level under both normal conditions and high-temperature and high-salt conditions. In particular, the |Z| of Example 4 (upper layer: 20% modified zirconium phosphate, lower layer: 5% second filler) 0.01Hz remains at the highest level under both normal conditions and high-temperature and high-salt conditions. It should be noted that the composite coating with a layered structure endows the coating with a new self-warning function while having high impedance (good anti-corrosion effect, no blistering).

[0100] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-warning anti-corrosion coating, the self-warning anti-corrosion coating includes an upper coating and a bottom coating, and is coated with a self-warning anti-corrosion paint, and is characterized in that: The self-warning anti-corrosion paint includes a first paint for forming the upper coating and a second paint for forming the bottom coating. The first paint contains modified zirconium phosphate and a first coating matrix; the second paint contains silica microcapsules and a second coating matrix; The modified zirconium phosphate is prepared by modifying zirconium phosphate with a modifier, and the modifier is selected from one of 3-(trimethoxysilyl)propyl methacrylate, 3-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; The silica microcapsules are prepared by impregnating mesoporous silica with tannic acid so that the inside of the silica microcapsules is loaded with tannic acid; In the first paint, the dosage of the modified zirconium phosphate relative to the first coating matrix is 5% to 30% by mass; in the second paint, the dosage of the silica microcapsules relative to the second coating matrix is 2% to 10% by mass.

2. The self-warning anti-corrosion coating according to claim 1, characterized in that: The first coating matrix and the second coating matrix are independently resin matrices.

3. The self-warning anti-corrosion coating according to claim 1, characterized in that: The first coating matrix and the second coating matrix are independently selected from at least one of epoxy resin, polyurea resin, and polyurethane.

4. The self-warning anti-corrosion coating according to claim 1, characterized in that: In the first paint, the dosage of the modified zirconium phosphate relative to the first coating matrix is 10% to 30% by mass; and / or in the second paint, the dosage of the silica microcapsules relative to the second coating matrix is 5% to 10% by mass.

5. The self-warning anti-corrosion coating according to claim 1, characterized in that: In the first paint, the dosage of the modified zirconium phosphate relative to the first coating matrix is 10% to 20% by mass.

6. The self-warning anti-corrosion coating according to claim 3, characterized in that: The modified zirconium phosphate is prepared by the following method: (i) Disperse zirconium phosphate in a buffer solution to obtain a zirconium phosphate dispersion; (ii) Dissolve the modifier in a modification solvent to obtain a modifier solution; (iii) Add the zirconium phosphate dispersion to the modifier solution for a modification reaction to obtain modified zirconium phosphate.

7. The self-warning anti-corrosion coating according to claim 6, characterized in that: The buffer solution is a tris(hydroxymethyl)aminomethane aqueous buffer solution with a concentration of 0.01M to 0.05M; and / or The modification solvent is one of ethanol and water.

8. The self-warning anti-corrosion coating according to claim 6, characterized in that: The mass fraction of zirconium phosphate in the zirconium phosphate dispersion is 0.5% to 3%; and / or The mass fraction of the modifier in the modifier solution is 0.25% to 1.5%.

9. The self-warning anti-corrosion coating according to any one of claims 1 to 8, characterized in that: The particle size of the mesoporous silica is 100 nm to 2 μm.

10. The self-warning anti-corrosion coating according to any one of claims 1 to 8, characterized in that: The mass ratio of tannic acid to mesoporous silica used during impregnation is 1 to 3:

1.

11. The self-warning anti-corrosion coating according to claim 9, characterized in that: The silica microcapsules are prepared by the following method: (I) Dispersing a template agent in a dispersion liquid for the template agent and emulsifying to obtain a template agent emulsion; (II) Adding a silica precursor to the template agent emulsion for a coating reaction to obtain silica-coated template agent microcapsules; (III) Performing a heat treatment on the silica-coated template agent microcapsules to obtain mesoporous silica; (IV) Impregnating the mesoporous silica with tannic acid to obtain silica microcapsules with tannic acid loaded inside.

12. The self-warning anti-corrosion coating according to claim 11, characterized in that: The template agent is cetyltrimethylammonium bromide; The dispersion liquid for the template agent is a mixed solution of ethanol and deionized water with a mass ratio of 9:1 to 1:

4.

13. The self-warning anti-corrosion coating according to claim 11, characterized in that: The mass fraction of the template agent in the template agent emulsion is 0.3% to 2.0%.

14. The self-warning anti-corrosion coating according to claim 11, characterized in that: The silica precursor is tetraethyl orthosilicate.

15. The self-warning anti-corrosion coating according to claim 11, characterized in that: The heating temperature of the heat treatment is 400 to 800 °C, and the treatment time is 3 to 5 hours.

16. The self-warning anti-corrosion coating according to any one of claims 1 to 8, characterized in that: The thickness of the bottom layer coating is 30 μm to 100 μm; and / or The thickness of the upper layer coating is 60 μm to 200 μm.

17. A method for anti-corrosion treatment of a metal material, characterized in that: The method includes the step of forming the self-warning anti-corrosion coating according to any one of claims 1 to 16 on the surface of the metal material.

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