Intelligent corrosion inhibition hydrogel with double functions of pH sensitivity and corrosion self-early warning as well as preparation and application of intelligent corrosion inhibition hydrogel

Abstract

The invention belongs to the technical field of anticorrosive paint, and discloses intelligent corrosion inhibition hydrogel with double functions of pH sensitivity and corrosion self-early warning, preparation of the intelligent corrosion inhibition hydrogel and application of the intelligent corrosion inhibition hydrogel in modified epoxy resin anticorrosive paint. The preparation method comprises the following steps: preparing a water phase from quaternary ammonium salt chitosan, methacrylic anhydride, a photoinitiator and a corrosion inhibitor, taking a Span emulsifier and paraffin as an oil phase, dropwise adding the water phase into the oil phase, rapidly stirring to form a water-in-oil emulsion system, and rapidly preparing the pH-sensitive hydrogel microspheres coated with the corrosion inhibitor through photo-crosslinking. And finally, forming the corrosion self-early-warning shell by using the tannic acid modified hydrogel microspheres by adopting an electrostatic adsorption layer-by-layer assembly method. The intelligent corrosion inhibitor hydrogel and the modified anticorrosive paint prepared by the invention have double functions of pH sensitivity and corrosion self-early warning. And meanwhile, the material is green and environment-friendly, the preparation process is simple, the cost is low, the corrosion resistance is effectively improved, the corrosion resistance is enriched, and long-acting corrosion prevention is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of anticorrosive coatings, and particularly relates to an intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning, its preparation, and its application in modified epoxy resin anticorrosive coatings. Background Art

[0002] Steel is one of the most widely used materials in current engineering applications, and its corrosion problem is an engineering problem that cannot be ignored. The corrosion of steel seriously affects the structural safety and service life, not only causing huge economic losses, but also possibly triggering safety disasters. Anticorrosive coating technology is the most common and direct method to deal with the corrosion problem of carbon steel. Traditional coatings mainly rely on constructing a physical barrier to isolate the metal from the corrosive medium to achieve corrosion protection. However, the long - term corrosion resistance of traditional coatings is poor, unable to cope with complex environmental changes, lacking the ability to monitor the corrosion process. Once the coating is damaged or eroded, it will even accelerate the corrosion process, and it is difficult to detect and take measures in the initial stage of corrosion.

[0003] In recent years, many researchers have proposed to improve the corrosion resistance of metals by adding various corrosion inhibitors in coatings, and the preparation and application of functional intelligent corrosion inhibitors have gradually attracted attention. By preparing a corrosion inhibitor carrier sensitive to changes in the corrosion environment (such as pH, temperature, and metal ion concentration), not only can the premature failure of the corrosion inhibitor be avoided, but also the release of the corrosion inhibitor can be controlled according to the corrosion state, providing functions such as long - term corrosion resistance, self - repair, and monitoring, thereby effectively protecting the substrate. At present, hydrogels have been widely studied in the field of drug loading in medicine due to their structural characteristics. However, the research on hydrogels in the field of metal corrosion resistance is in its infancy. Their rich groups provide diverse properties, bringing many potential possibilities to the field of metal corrosion resistance and having a bright development prospect. Summary of the Invention

[0004] In order to overcome the above - mentioned disadvantages and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of an intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning.

[0005] Another object of the present invention is to provide an intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning prepared by the above - mentioned method.

[0006] Another object of the present invention is to provide the application of the above - mentioned intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning in anticorrosive coatings.

[0007] Another object of the present invention is to provide a modified epoxy resin anticorrosive coating.

[0008] The objects of the present invention are achieved by the following solutions:

[0009] A preparation method of an intelligent corrosion inhibitor hydrogel with dual functions of pH sensitivity and corrosion self-warning includes the following steps:

[0010] Step 1: React quaternary ammonium chitosan with methacrylic anhydride to obtain a quaternary ammonium methacrylate chitosan prepolymer, and then mix the quaternary ammonium methacrylate chitosan prepolymer, corrosion inhibitor, water, and photoinitiator evenly to prepare an aqueous phase; mix an emulsifier and paraffin and stir evenly to prepare an oil phase; add the aqueous phase to the oil phase and stir to form a uniform and stable milky white emulsion, and then carry out UV photocrosslinking on the milky white emulsion to obtain pH-sensitive intelligent hydrogel microsphere powder coated with a corrosion inhibitor;

[0011] Step 2: Immerse the pH-sensitive intelligent hydrogel microsphere powder coated with a corrosion inhibitor prepared in Step 1 completely in an aqueous tannic acid solution, filter, and dry to obtain an intelligent corrosion inhibitor with dual functions of pH sensitivity and corrosion self-warning.

[0012] In Step 1, the mass ratio of the quaternary ammonium chitosan to methacrylic anhydride is 1:(0.5 - 2).

[0013] The reaction of quaternary ammonium chitosan with methacrylic anhydride in Step 1 means reacting at 25 - 80°C for 6 - 12 h; preferably, first stir and swell the quaternary ammonium chitosan in water and then add methacrylic anhydride and react at 25 - 80°C for 6 - 12 h.

[0014] After the reaction of quaternary ammonium chitosan with methacrylic anhydride in Step 1, it is preferably to dialyze and dry the obtained product to obtain a quaternary ammonium methacrylate chitosan prepolymer. Among them, dialysis is preferably carried out with a dialysis bag having a cut-off molecular weight of 8000.

[0015] The photoinitiator in Step 1 is a water-soluble free radical photoinitiator, such as one of lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (LAP), 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959), and benzophenone;

[0016] The corrosion inhibitor in Step 1 is at least one of aqueous corrosion inhibitors such as sodium citrate (SC), sodium gluconate (SG), and sodium molybdate (Na2MoO4).

[0017] In the aqueous phase in Step 1, the mass ratio of the quaternary ammonium methacrylate chitosan prepolymer, corrosion inhibitor, and water is 10 - 20:0 - 3:100; the mass of the photoinitiator accounts for 0.1 - 1 wt% of the mass of the aqueous phase.

[0018] The emulsifier in Step 1 is at least one of Span 80, Span 85, span 60, and polyglycerol ricinoleate (PGPR);

[0019] The volume ratio of the emulsifier to the paraffin in the oil phase described in Step 1 is 1:(5 - 50);

[0020] The volume ratio of the water phase to the oil phase described in Step 1 is 3:(5 - 15).

[0021] The stirring in Step 1 to form a uniform and stable milky white emulsion is preferably carried out at 1400 - 2500 rpm for 2 - 4 h.

[0022] The UV photocrosslinking described in Step 1 refers to photocrosslinking by irradiating with a 365 - 405 nm ultraviolet lamp, and the irradiation time is 5 - 30 min until complete curing; after photocrosslinking, washing and drying with isopropanol and ethanol in sequence to obtain the pH - sensitive intelligent hydrogel microsphere powder coated with the corrosion inhibitor.

[0023] The concentration of the tannic acid aqueous solution described in Step 2 is 1 - 100 g / L.

[0024] The mass ratio of the tannic acid aqueous solution to the pH - sensitive intelligent hydrogel microsphere powder coated with the corrosion inhibitor described in Step 2 is 100:(0.5 - 5).

[0025] The immersion described in Step 2 means immersion at room temperature for 12 - 24 h;

[0026] The drying described in Step 2 means freeze - drying.

[0027] An intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning prepared by the above method.

[0028] The application of the above intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning as a corrosion inhibitor, especially its application as a corrosion inhibitor in an acidic environment / saline environment.

[0029] An epoxy resin anticorrosive coating, which includes epoxy resin, the above intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning, a diluent and a curing agent, wherein the content of the intelligent corrosion - inhibiting hydrogel with dual functions of pH - sensitivity and corrosion self - warning in the anticorrosive coating is 0.01 - 10 wt%.

[0030] The curing agent described is polyurethane;

[0031] The diluent described is at least one of anhydrous ethanol, propanol, and ethyl acetate.

[0032] The mass ratio of the epoxy resin, the curing agent, and the diluent is 1:1:(0 - 0.6).

[0033] A preparation method of the above-mentioned epoxy resin anti-corrosion coating, which comprises the following steps: dispersing an intelligent corrosion inhibitor hydrogel with dual functions of pH sensitivity and corrosion self-warning as a filler into a diluent, and then uniformly mixing it with an epoxy resin and a curing agent to obtain the epoxy resin anti-corrosion coating.

[0034] Application of the above-mentioned epoxy resin anti-corrosion coating in an acidic environment / saline environment.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) It has dual functions. The pH sensitivity enables the corrosion inhibitor to be released according to the changes in a specific corrosion environment. The corrosion self-warning function determines the specific corrosion condition and location through color change. Together, they achieve a rapid response at the initial stage of corrosion and inhibit the metal corrosion rate.

[0037] (2) The materials are green, environmentally friendly, and inexpensive. A large number of materials used, such as natural organic macromolecule chitosan, green aqueous corrosion inhibitor, tannic acid, etc., are green, safe, environmentally friendly, and low-cost. Moreover, the materials used already have a certain corrosion inhibition effect, and the prepared composite corrosion inhibitor significantly enhances the long-term corrosion resistance of the anti-corrosion coating.

[0038] (3) The process is safe and simple. The basic environment for material synthesis is an aqueous solution, which is easy to operate and safe. The synthesized materials show excellent adaptability and can be widely compatible with a variety of process methods. In addition to the emulsion cross-linking method, 3D printing, microfluidic technology, mechanical grinding and refinement, etc. can also be used.

[0039] (4) The prepared hydrogel has chemical cross-linking and physical bond cross-linking, is more stable, has rich functions, and has diverse anti-corrosion principles, effectively coping with complex corrosion environments. Description of the Drawings

[0040] Figure 1 A pH-sensitive intelligent corrosion inhibitor hydrogel SC@QCSMA microsphere encapsulating a corrosion inhibitor prepared by emulsion photocrosslinking in Example 1.

[0041] Figure 2 Swelling properties of the SC@QCSMA@TA hydrogel prepared in Example 2 in solutions with different pH values.

[0042] Figure 3 Potentiodynamic polarization curves of Q235 steel immersed in 3.5 wt% NaCl solution containing different corrosion inhibitors for 12 h.

[0043] Figure 4 Potentiodynamic polarization curves of Q235 steel immersed in HCl solution containing different corrosion inhibitors for 12 h.

[0044] Figure 5Electrochemical impedance spectroscopy diagrams of Q235 steel with different coatings on its surface immersed in 3.5 wt% NaCl solution for 1 day and 35 days. The tested coatings are the SC@QCSMA-E44 coating prepared in Example 3, the SC@QCSMA@TA-E44 coating prepared in Example 4, and the pure E44 epoxy resin coating.

[0045] Figure 6 Morphology diagrams of Q235 steel immersed in 3.5 wt% NaCl solution without corrosion inhibitor (a) and containing SC@QCSMA@TA of Example 2 (b) for 7 days.

[0046] Figure 7 Morphology diagrams of different coatings on the surface immersed in 3.5 wt% NaCl for 35 days; (a) is the SC@QCSMA@TA-E44 coating prepared in Example 4; (b) is the partially enlarged morphology diagram of (a); (c) is the pure E44 epoxy resin coating; (d) is the partially enlarged morphology diagram of (c). Detailed implementation manners

[0047] The present invention will be further described in detail below in conjunction with examples and drawings, but the implementation manners of the present invention are not limited thereto. For those not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0048] The reagents used in the examples can be conventionally purchased from the market without special instructions.

[0049] Example 1

[0050] A preparation method of pH-sensitive intelligent corrosion inhibitor hydrogel microspheres coated with corrosion inhibitors is proposed. The preparation method includes the following steps:

[0051] Step 1: Prepare a water-soluble prepolymer with photosensitive groups: Stir and dissolve 1.6 g of quaternary ammonium salt chitosan in 25 mL of deionized water and fully swell. Dropwise add 1.6 g of methacrylic anhydride and heat in a water bath at 60 °C for 12 h to obtain a hydrogel precursor solution. The hydrogel precursor solution is dialyzed in deionized water with MW8000 for 72 h and freeze-dried for 48 h to obtain a methacrylic quaternary ammonium salt chitosan prepolymer with photosensitive groups, denoted as QCSMA.

[0052] Step 2: Preparation of water-in-oil emulsion system: First, prepare the aqueous phase: Mix the quaternary ammonium salt of methacrylic acid chitosan prepolymer QCSMA, sodium citrate SC, and water prepared in Step 1 in a mass ratio of 15:3:100 uniformly, and then add lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (LAP) accounting for 0.5 wt% of the mass of the aqueous phase and mix uniformly to obtain the aqueous phase; Then, prepare the oil phase: Mix Span-80 and paraffin uniformly, where the volume content of Span-80 is 2%; Finally, prepare the water-in-oil system: Use a 1 mL syringe with a needle hole of 0.7 mm to suck 3 mL of the aqueous phase and inject it drop by drop into 10 mL of the oil phase, and stir the water-in-oil system with a magnetic stirrer at a speed of 1400 r / min for 2 h to form a uniform and stable white emulsion.

[0053] Step 3: UV photocrosslinking: Irradiate the water-in-oil emulsion system prepared in Step 2 with a magnetic stirrer rotating at 400 r / min using a 405 nm ultraviolet lamp, and irradiate with ultraviolet light for 30 min to fully crosslink it. Filter the photocrosslinked microsphere emulsion, wash it 3 times with isopropanol and ethanol in sequence, and then dry it in vacuum at 60 °C for 24 h to obtain pH-sensitive intelligent hydrogel microspheres coated with sodium citrate, denoted as SC@QCSMA.

[0054] Example 2

[0055] A preparation method of pH-sensitive and corrosion self-warning bifunctional intelligent corrosion inhibition hydrogel powder is proposed. Steps 1-3 in this example are exactly the same as those in Example 1 and will not be elaborated here. The specific preparation step 4 is as follows:

[0056] Step 4: At room temperature, immerse the pH-sensitive intelligent hydrogel microsphere powder SC@QCSMA coated with sodium citrate prepared in Step 3 in a 50 g / L tannic acid TA aqueous solution for 24 h, and the mass ratio of SC@QCSMA to the tannic acid TA aqueous solution is 1 wt%. Take out the hydrogel that has been fully swollen by TA immersion and dry it in vacuum for 48 h to obtain the SC@QCSMA@TA hydrogel.

[0057] Example 3

[0058] A preparation method of a pH-sensitive intelligent corrosion inhibition hydrogel modified epoxy resin anticorrosive coating is proposed. Steps 1-3 in this example are exactly the same as those in Example 1 and will not be elaborated here. The specific preparation step 4 is as follows:

[0059] Step 4: Use E44 epoxy resin as the matrix resin, polyurethane 650 as the curing agent, and absolute ethanol as the diluent, and mix them in a mass ratio of 5:5:3. First, place E44 epoxy resin and polyurethane 650 at 50 °C to expel the air in the fluid and enhance the fluidity; take the pH-sensitive intelligent corrosion inhibitor hydrogel SC@QCSMA and add it to the diluent absolute ethanol. After ultrasonic dispersion for 10 min, add it to the epoxy resin. Then, stir evenly with a glass rod for 5 min and perform ultrasonic treatment for 5 min; subsequently, add polyurethane 650 and stir evenly. After ultrasonic treatment for 5 min, place it in a vacuum box for low-pressure exhaust and then take it out to obtain the SC@QCSMA-E44 coating, where the concentration of the pH-sensitive intelligent corrosion inhibitor hydrogel SC@QCSMA is 1 wt%.

[0060] Example 4

[0061] A preparation method of an intelligent corrosion inhibitor hydrogel modified epoxy resin anticorrosive coating with dual functions of pH sensitivity and corrosion self-warning is proposed. In this example, Steps 1-4 are exactly the same as those in Example 2 and will not be elaborated here. The specific preparation Step 5 is as follows:

[0062] Step 5: Use E44 epoxy resin as the matrix resin, polyurethane 650 as the curing agent, and absolute ethanol as the diluent, and mix them in a mass ratio of 5:5:3. First, place E44 epoxy resin and polyurethane 650 at 50 °C to expel the air in the fluid and enhance the fluidity; take the intelligent corrosion inhibitor hydrogel SC@QCSMA@TA with dual functions of pH sensitivity and corrosion self-warning and add it to the diluent absolute ethanol. After ultrasonic dispersion for 10 min, add it to the epoxy resin. Then, stir evenly with a glass rod for 5 min and perform ultrasonic treatment for 5 min; subsequently, add polyurethane 650 and stir evenly. After ultrasonic treatment for 5 min, place it in a vacuum box for low-pressure exhaust and then take it out to obtain the SC@QCSMA@TA-E44 coating, where the concentration of the intelligent corrosion inhibitor hydrogel SC@QCSMA@TA with dual functions of pH sensitivity and corrosion self-warning is 1 wt%.

[0063] The corrosion inhibitors and coatings in the above examples and comparative examples were tested as follows:

[0064] (1) Macroscopic morphology observation;

[0065] (2) Swelling performance test and pH sensitivity of the hydrogel;

[0066] (3) Polarization curve corrosion study;

[0067] (4) Electrochemical impedance spectroscopy test.

[0068] Figure 1 Microscopic morphology diagram of the pH-sensitive intelligent corrosion inhibitor hydrogel SC@QCSMA encapsulating the corrosion inhibitor prepared by emulsion photocrosslinking for Example 1;

[0069] Figure 2 For the swelling properties of the SC@QCSMA@TA hydrogel in different pH solutions in Example 2. The SC@QCSMA@TA hydrogel was freeze-dried and weighed, denoted as M1. Then, it was immersed in different experimental soaking solutions (HCl solution with pH = 4, aqueous solution with pH = 7, NaOH solution with pH = 10). The samples were taken out every 1 h, and the surface moisture was blotted with filter paper and the swollen mass was weighed, denoted as M2. The swelling ratio (Swelling Factor, Swelling Factor = M2 / M1) represents the mass change of the hydrogel before and after soaking. As Figure 2 can be seen, the SC@QCSMA@TA hydrogel reaches the maximum swelling value and the swelling equilibrium state faster under acidic conditions, has the largest swelling degree, and has pH sensitivity to the acidic environment.

[0070] Figure 3 For the potentiodynamic polarization curves of Q235 steel immersed in 3.5 wt% NaCl solution containing different corrosion inhibitors for 12 h. The corrosion inhibitors include SC@QCSMA in Example 1 and SC@QCSMA@TA in Example 2. A three-electrode system was used for potentiodynamic polarization testing. The working electrode was the surface of a Q235 steel column encapsulated with epoxy resin with a diameter of 12 mm, the reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The test potential range was ±0.5 V of the OCP potential, and the scanning rate was 0.1 mV / s. Before the test, the OCP potential was measured first. After its floating range was within ±2 mV, the potentiodynamic polarization curve test was carried out. In the figure, Q235 steel, 1 wt% SC@QCSMA, and 1 wt% SC@QCSMA@TA correspond to immersing Q235 steel in 100 mL of 3.5 wt% NaCl solution, 100 mL of 3.5 wt% NaCl solution containing 1 wt% SC@QCSMA, and 100 mL of 3.5 wt% NaCl solution containing 1 wt% SC@QCSMA@TA, respectively. After soaking for 24 h, the potentiodynamic polarization curve test was carried out. It can be seen from the figure that Q235 steel immersed in 3.5 wt% Nacl solution containing 1 wt% SC@QCSMA and 3.5 wt% Nacl solution containing 1 wt% SC@QCSMA@TA both showed a significant increase in corrosion voltage and a significant decrease in corrosion current, indicating that the corrosion resistance of Q235 steel was enhanced compared to that of Q235 steel, and an excellent corrosion inhibition effect was achieved.

[0071] Figure 4The potentiodynamic polarization curves of Q235 steel immersed in HCl solutions containing different corrosion inhibitors for 12 h are shown. The corrosion inhibitors include SC, TA, Example 1 SC@QCSMA, and Example 2 SC@QCSMA@TA. A three-electrode system was used for potentiodynamic polarization testing. The working electrode was the surface of a Q235 steel column encapsulated with epoxy resin with a diameter of 12 mm. The reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The test potential range was ±0.5 V of the OCP potential, and the scanning rate was 0.1 mV / s. Before the test, the OCP potential was measured first. After its floating range was within ±2 mV, the potentiodynamic polarization curve test was carried out. In the figure, Q235 steel, SC, TA, SC@QCSMA, and SC@QCSMA@TA correspond to immersing Q235 steel in 100 mL of HCl solution with pH = 4, 100 mL of HCl solution with pH = 4 containing 1 wt% SC, 100 mL of HCl solution with pH = 4 containing 1 wt% TA, 100 mL of HCl solution with pH = 4 containing 1 wt% SC@QCSMA, and 100 mL of HCl solution with pH = 4 containing 1 wt% SC@QCSMA@TA, respectively. After soaking for 24 h, the potentiodynamic polarization curve test was carried out. It can be seen from the figure that when tannic acid TA and sodium citrate SC are used directly as corrosion inhibitors, the corrosion inhibition effect is inferior to the self-protection effect of Q235 steel in an acidic environment. Compared with directly immersing Q235 steel, after coating with QCSMA hydrogel, the corrosion voltage increases significantly, and the corrosion tendency decreases, showing excellent corrosion inhibition effect in an acidic environment.

[0072] Figure 5 The electrochemical impedance spectroscopy diagrams of Q235 steel with different coatings on its surface immersed in 3.5 wt% NaCl solution for 1 d and 35 d are shown. A three-electrode system was used for electrochemistry impedance spectroscopy testing. The working electrodes were Q235 steel columns with the same thickness of the SC@QCSMA-E44 coating prepared in Example 3, the @QCSMA@TA-E44 coating prepared in Example 4, and the pure E44 epoxy resin coating on their surfaces, respectively. The reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The Q235 steel columns with the SC@QCSMA@TA-E44 coating and the pure E44 epoxy resin coating on their surfaces were respectively immersed in 100 mL of 3.5 wt% NaCl, and the low-frequency impedance modulus values were measured. It is known that the larger the low-frequency impedance modulus value, the better the corrosion resistance. According to the figure, after soaking for 1 day and 35 days, the impedance modulus values corresponding to 0.01 Hz of the SC@QCSMA-E44 coating and the SC@QCSMA@TA-E44 coating are much higher than those of the pure E44 epoxy resin coating, showing good long-term corrosion resistance.

[0073] Figure 6Morphology diagrams of Q235 steel immersed in 3.5 wt% NaCl solution containing different corrosion inhibitors for 7 days; (a) 3.5 wt% NaCl solution without added corrosion inhibitor; (b) 3.5 wt% NaCl solution added with 1 wt% SC@QCSMA@TA intelligent corrosion inhibitor of Example 2. The corrosion morphology corresponds to Figure 3 the results of potentiodynamic polarization curves, further proving that the pH-sensitive and corrosion self-warning dual-functional intelligent corrosion inhibitor prepared by the present invention has good anti-corrosion performance and corrosion self-warning property.

[0074] Figure 7 Morphology diagrams of different coatings immersed in 3.5 wt% NaCl for 35 days; (a) SC@QCSMA@TA-E44 coating prepared in Example 4; (b) partially enlarged morphology diagram of (a); (c) E44 epoxy resin coating; (d) partially enlarged morphology diagram of (c). It can be observed that the color of some corrosion positions of the SC@QCSMA@TA-E44 coating is more obvious, showing dark purple. Tannic acid forms a complex with iron ions, inhibiting the corrosion reaction. While there are multiple corrosion pits in the pure E44 epoxy coating without added corrosion inhibitor, accelerating the corrosion process. The corrosion morphology corresponds to Figure 5 the results of electrochemical impedance experiments, further proving that the pH-sensitive and corrosion self-warning dual-functional modified epoxy resin anti-corrosion coating prepared by the present invention has excellent long-term corrosion resistance and corrosion self-warning property for enhancing anti-corrosion coatings.

[0075] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing an intelligent corrosion-inhibiting hydrogel having the dual functions of pH sensitivity and corrosion self-warning, characterized in that The following steps are involved: Step 1: reacting quaternary ammonium salt chitosan and methacrylic anhydride to obtain methacrylic ammonium salt chitosan prepolymer, then uniformly mixing methacrylic ammonium salt chitosan prepolymer, corrosion inhibitor, water and photoinitiator to prepare an aqueous phase; mixing an emulsifier and paraffin wax, stirring uniformly to prepare an oil phase; adding the aqueous phase to the oil phase and stirring to form a uniform and stable milky white emulsion, and then UV light cross-linking the milky white emulsion to obtain a pH-sensitive smart hydrogel microsphere powder coated with a corrosion inhibitor; Step 2: The pH-sensitive smart hydrogel microsphere powder coated with the corrosion inhibitor prepared in step 1 is fully immersed in a tannic acid aqueous solution, filtered, and dried to obtain a pH-sensitive and corrosion self-warning dual-function smart corrosion inhibitor.

2. The method for preparing the intelligent corrosion-inhibiting hydrogel having the dual functions of pH sensitivity and corrosion self-warning according to claim 1, characterized in that: The photoinitiator described in step 1 is a water-soluble free radical photoinitiator, preferably one of phenyl (2,4,6-trimethylbenzoyl) lithium phosphinate, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and xylene ketone; The corrosion inhibitor described in step 1 is an aqueous corrosion inhibitor, preferably at least one of sodium citrate, sodium gluconate, and sodium molybdate.

3. The method for preparing the intelligent corrosion-inhibiting hydrogel having the dual functions of pH sensitivity and corrosion self-warning according to claim 1, characterized in that: The mass ratio of the quaternary ammonium salt chitosan and methacrylic anhydride described in step 1 is 1:(0.5-2); The step 1 of reacting quaternary ammonium salt chitosan and methacrylic anhydride is to react at 25-80° C. for 6-12 hours; The mass ratio of methyl acrylate quaternary ammonium salt chitosan prepolymer, corrosion inhibitor and water in the aqueous phase described in step 1 is 10-20:0-3:100; the mass of the photoinitiator accounts for 0.1-1wt% of the mass of the aqueous phase; The emulsifier described in step 1 is at least one of Span 80, Span 85, Span 60, and polyglycerol ricinoleate; The volume ratio of the emulsifier to the paraffin in the oil phase described in step 1 is 1:(5-50); The volume ratio of the water phase to the oil phase described in step 1 is 3:(5-15); The stirring in step 1 to form a uniform and stable milky white emulsion is preferably carried out at 1400-2500 rpm for 2-4 hours; The UV light crosslinking described in step 1 refers to light crosslinking by irradiation with a 365-405 nm ultraviolet lamp, and the irradiation time is 5-30 minutes until complete curing.

4. The method for preparing the intelligent corrosion-inhibiting hydrogel having the dual functions of pH sensitivity and corrosion self-warning according to claim 1, characterized in that: The concentration of the tannic acid aqueous solution described in step 2 is 1 to 100 g / L; The mass ratio of the tannic acid aqueous solution and the pH-sensitive smart hydrogel microsphere powder coated with the corrosion inhibitor described in step 2 is 100:(0.5-5); The immersion described in step 2 refers to immersion at room temperature for 12 to 24 hours.

5. An intelligent corrosion-inhibiting hydrogel having the dual functions of pH sensitivity and corrosion self-warning, prepared according to the method described in any one of claims 1 to 4.

6. Use of the intelligent corrosion-inhibiting hydrogel with dual functions of pH sensitivity and corrosion self-warning according to claim 5 as a corrosion inhibitor, especially as a corrosion inhibitor in an acidic environment / salty environment.

7. An epoxy resin anticorrosive coating, characterized in that The invention comprises epoxy resin, the intelligent corrosion-inhibiting hydrogel with dual functions of pH sensitivity and corrosion self-warning as claimed in any one of claims 1 to 4, a diluent and a curing agent.

8. The epoxy resin anticorrosive coating according to claim 7, characterized in that: The curing agent is polyurethane; The diluent is at least one of anhydrous ethanol, propanol and ethyl acetate; The mass ratio of the epoxy resin, the curing agent and the diluent is 1:1:(0-0.6), and the content of the intelligent corrosion-inhibiting hydrogel with the dual functions of pH sensitivity and corrosion self-warning in the anti-corrosion coating is 0.01-10wt%.

9. A method for preparing the epoxy resin anticorrosive coating according to claim 8, characterized in that The following steps are involved: The intelligent corrosion-inhibiting hydrogel with dual functions of pH sensitivity and corrosion self-warning is dispersed into a diluent as a filler, and then evenly mixed with an epoxy resin and a curing agent to prepare an epoxy resin anti-corrosion coating.

10. Use of the epoxy resin anticorrosive coating according to claim 9 in an acidic environment or a saline environment.

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