Environmental response type steel structure nano-composite anticorrosive coating composition

Abstract

The invention discloses an environment-responsive steel structure nano-composite anticorrosive coating composition, which is prepared from the following raw materials in parts by mass: 100 parts of coating resin dispersion, 2 to 2.4 parts of pH responsive polymer microcapsules and 1.1 to 1.4 parts of dispersing agent, the particle size of the pH responsive polymer microcapsules is 300 to 500 nm, and a slow release agent is coated in the pH responsive polymer microcapsules. The wall material of the pH responsive polymer microcapsule is a dimethylaminoethyl methacrylate (DMAEMA)-methacrylic acid (MAA) copolymer; and the slow-release agent comprises benzotriazole (BTA) and sodium molybdate, so that intelligent response in an acid-base environment is realized, accelerated failure of the coating is effectively prevented, and the long-acting protection anti-corrosion effect of the coating of the coating composition is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the corrosion protection of outdoor steel structures, and in particular to an environment-responsive nanocomposite corrosion protection coating composition for steel structures. BACKGROUND

[0002] Outdoor steel structures are generally protected by corrosion protection coatings on their surfaces due to long-term exposure to harsh environments such as chemical atmospheres and marine salt spray. However, under the alternating wet and hot conditions, dry-wet cycles and the erosion of pollutants, the base metal of the steel structure is prone to electrochemical corrosion, leading to a decrease in structural strength and a sharp reduction in service life. Therefore, the development of long-acting corrosion protection coatings is a core requirement for ensuring the safe operation of infrastructure.

[0003] Current mainstream corrosion protection coatings rely on physical shielding or cathodic protection mechanisms, although they have basic protection capabilities, they have significant limitations: when the coating is subjected to mechanical impact, friction or stress deformation, micron-sized cracks or scratches are easily produced; when acid rain, deicing salt or alkaline leachate penetrates the damaged area, the corrosion medium accumulates at the defect, inducing local galvanic corrosion. At this time, traditional coatings lack active defense mechanisms and can only delay but not stop the spread of corrosion.

[0004] More seriously, the rust produced by local corrosion will expand in volume, causing peeling stress on the surrounding intact coating, triggering a chain of failures such as blistering and delamination. This vicious cycle of "damage-corrosion-diffusion" allows the initial damage of micron-sized to spread to a centimeter-sized failure area, significantly shortening the maintenance cycle. Therefore, for the corrosion protection of outdoor steel structures, achieving environment-adaptive response and targeted repair of damaged areas, and precisely blocking the corrosion diffusion path at the initial stage of local damage, are important research directions for long-term effective corrosion protection of outdoor steel structures. SUMMARY

[0005] To improve the long-term corrosion resistance of outdoor steel structures, an environment-responsive nanocomposite corrosion protection coating composition for steel structures is provided.

[0006] The above first invention object of the present application is achieved by the following technical solution: An environment-responsive nanocomposite corrosion protection coating composition for steel structures, comprising the following mass fractions of raw materials: 100 parts of a coating resin dispersion, 2-2.4 parts of pH-responsive polymer microcapsules, 1.1-1.4 parts of a dispersant, The pH-responsive polymer microcapsules have a particle size of 300-500 nm and contain a sustained-release agent inside; the wall material of the pH-responsive polymer microcapsules is a copolymer of dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MAA); The sustained-release agent includes benzotriazole (BTA) and sodium molybdate.

[0007] By using the above technical solution, dimethylaminoethyl methacrylate-methacrylic acid copolymer is used as a wall material to coat the sustained-release agent to form a pH-responsive polymer microcapsule, and then the pH-responsive polymer microcapsule is dispersed in a coating resin dispersion, and after the coating is coated and cured to form a coating layer, the pH-responsive polymer microcapsule will be dispersed in the coating layer; When the coating layer contacts an acidic corrosive environment, MMA contacts and responds to the acidic corrosive environment to swell, causing the pH-responsive polymer microcapsule to break and release the sustained-release agent in the pH-responsive polymer microcapsule, thereby hindering the continuation of the acidic corrosion; When the coating layer contacts an alkaline corrosive environment, DMAEMA contacts and responds to the alkaline corrosive environment to swell, causing the pH-responsive polymer microcapsule to break and release the sustained-release agent in the pH-responsive polymer microcapsule, thereby hindering the continuation of the alkaline corrosion; Thus, the acid and alkali environment is intelligently responded, the accelerated failure of the coating layer is effectively blocked, and the corrosion protection effect of the coating composition in coating the coating layer is significantly improved.

[0008] In addition, in the present application, thiolated chitosan is grafted outside the pH-responsive polymer microcapsule, and fluorosilane modified montmorillonite is added; Targeted repair effect of microcapsule surface grafted with thiolated chitosan: Thiolated chitosan (MW=10kDa) forms a strong coordination bond with Fe³⁺ in the rust area of the steel matrix through its thiol group (-SH), so that the microcapsule is actively enriched in the damaged or rusted active points of the coating layer, the local microcapsule concentration is improved, and the directional enrichment ensures that the sustained-release agent is accurately released at the initial stage of corrosion, avoiding the repair delay problem caused by uneven distribution of repair components in traditional coatings; The fluorosilane modified montmorillonite introduces superhydrophobicity through perfluoro chains, the nanosheet layers are directionally arranged in the coating layer to form a penetration path with high tortuosity, forcing the diffusion distance of corrosive media (such as Cl⁻, H2O) to be extended, and the epoxy groups on the surface of the montmorillonite sheet layer form chemical crosslinking with the resin matrix, so that the interfacial adhesion is improved, and the bubbling and peeling in a humid environment are effectively inhibited; Between the two, the barrier effect of montmorillonite delays the diffusion of corrosive media, providing a longer time window for the pH-responsive release of the microcapsule; the site-specific repair of the microcapsule reduces the stress of the coating layer caused by the volume expansion of the rust products, avoiding the risk of failure of the montmorillonite sheet layer due to cracking of the coating layer, and synergistically enhancing the corrosion protection effect of the coating layer in acid / alkali / salt environments.

[0009] Optionally, the sustained-release agent is a mixture of BTA, sodium molybdate and benzoate in a mass ratio of 1:1:0.5.

[0010] By adopting the technical scheme, BTA is complexed with Fe²⁺ to generate a dense [Fe(BTA)2] chelate film to block anode dissolution, and sodium molybdate catalyzes the oxidation of Fe²⁺ into a γ-FeOOH passivation layer to repair cathode defects, so that the corrosion current density is reduced, and electrochemical corrosion is slowed down; In addition, in an acidic environment, benzoate is dissociated into benzoic acid molecules (C6H5COOH), and the carboxyl group of benzoic acid forms a coordination bond with the Fe atoms on the steel surface, on the one hand, the hydrophobic benzene ring is vertically adsorbed to form a physical barrier layer, reducing the interfacial energy and significantly inhibiting the penetration of Cl⁻ / H2O, on the other hand, the benzoic acid-BTA hydrogen bond network reduces the interfacial energy, guides the [Fe(BTA)2] chelate film to cover the metal surface corroded, and together forms a high-density composite film, which has better corrosion protection effect; in an alkaline environment, the benzoate root of the benzoate salt repels OH⁻ to continuously passivate the cathode area, and inhibits corrosion from occurring; Therefore, the benzoate, benzotriazole (BTA) and sodium molybdate form a synergistic corrosion inhibition system, and a dense composite protective layer is constructed on the metal surface to achieve excellent corrosion protection effect.

[0011] Optionally, the mass ratio of dimethylaminoethyl methacrylate (DMAEMA) to methacrylic acid (MAA) in the copolymer of dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MAA) is 70:30.

[0012] By optimizing the ratio of DMAEMA and MAA in the wall material, the pH response threshold and mechanical strength can be considered, the pH-responsive polymer microcapsule is stable at room temperature, and can quickly respond to contact with acid and alkali to release the slow-release agent.

[0013] Optionally, the crosslinking agent used in the preparation process of the copolymer of dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MAA) is pentaerythritol triacrylate (PETA).

[0014] By adopting the technical scheme, PETA forms a network structure in the wall material, reduces the water absorption rate of the wall material, and provides its fracture shear strength, thereby on the one hand, the breakage loss of the pH-responsive polymer microcapsule mixed into the coating resin dispersion can be reduced, and on the other hand, the stability of the pH-responsive polymer microcapsule in a high-humidity environment can be improved, avoiding the premature failure of the pH-responsive polymer microcapsule in a high-speed environment.

[0015] Optionally, the pH-responsive polymer microcapsule is externally grafted with mercaptized chitosan (MW=10kDa).

[0016] By adopting the technical scheme, rust often occurs on the surface of the paint coating object, and although surface polishing treatment is performed, complete rust removal and smooth surface polishing cannot be achieved for large outdoor steel structures, and micron-level surface defects and corrosion sites still exist on the surface. In this way, the surface of the pH-responsive polymer microcapsule is grafted with thiolated chitosan, Fe-S coordination bonds are formed in the rust micro-area, the pH-responsive polymer microcapsule is enriched at the active corrosion site, the density of the pH-responsive polymer microcapsule in the rust area is increased, and the corrosion prevention effect is improved.

[0017] Optionally, the fluorosilane modified montmorillonite is further included in an amount of 5.2-7.5 parts.

[0018] By adopting the technical scheme, the fluorosilane modification makes the nanosheet layer of the montmorillonite have a lower surface energy and improved hydrophobicity, and after being mixed and dispersed in the coating, the diffusion path of the corrosive medium is forced to be lengthened, and the corrosion is slowed down.

[0019] Optionally, the modifier used for the fluorosilane modification of the montmorillonite is a compound of perfluorooctyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0020] By adopting the technical scheme, the montmorillonite is modified using the compound of perfluorooctyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, the perfluorooctyltriethoxysilane grafts introduces a perfluorinated chain to provide superhydrophobicity, and the γ-glycidoxypropyltrimethoxysilane grafts introduces an epoxy agent to enhance the interfacial adhesion, thereby further improving the anti-bubbling property of the coating when immersed in an acid or alkali liquid, and further improving the corrosion resistance of the coating.

[0021] Optionally, the coating further includes inorganic pigments 30-40 parts and polyamide wax paste 1.8-2.6 parts.

[0022] By adopting the technical scheme, pigments are often added to the coating to enhance the shielding property of the material, the mechanical property of the coating, and to identify the integrity of the coating, the addition of inorganic pigments will obviously affect the stability of the distribution of the pH-responsive polymer microcapsule in the coating and the distribution of the wet coating layer during coating, and therefore the polyamide wax paste is added at the same time as the inorganic pigments, the polyamide wax paste forms a gel network structure in the coating composition as a thixotropic thickening agent, the coating composition has a yield value, and the coating composition is prevented from settling and resolving after mixing, and the coating composition can be temporarily disintegrated under external force during coating, the viscosity is suddenly reduced, and the construction is facilitated.

[0023] In summary, the present application has at least the following beneficial effects: 1. Through the intelligent release mechanism of pH-responsive microcapsules, the targeted release of corrosion inhibitors is quickly triggered when acid or alkaline corrosion occurs, blocking the corrosion electrochemical reaction and effectively preventing the chain failure caused by rust diffusion at the coating damage site; 2. Combining molecular-level corrosion inhibition passivation, targeted repair enhancement, nanometer barrier, and system state maintenance technology, a comprehensive protection closed loop is formed from metal substrate protection to corrosion medium blocking, significantly improving the durability of the coating in complex environments; 3. Innovative use of thixotropic network stabilizing functional component distribution to solve the problem of pH-responsive polymer microcapsule failure caused by the addition of inorganic pigments, achieving synergistic enhancement of corrosion protection performance under high pigment load, and expanding the application scenarios of the coating industry. DETAILED DESCRIPTION

[0025] Raw materials Sodium benzoate, sodium molybdate, BTA are reagents from Sinopharm, analytical grade.

[0026] Sodium dodecyl sulfate, anhydrous ethanol, toluene, glacial acetic acid are commercially available products.

[0027] Span-80 is a commercially available product from Croda.

[0028] DMAEMA is a commercially available product from Sigma-Aldrich.

[0029] Methacrylic acid (MAA) is a commercially available product from Alfa Aesar.

[0030] Pentaerythritol triacrylate (PETA) is a commercially available product from Sartomer (Arkema).

[0031] AIBN is a commercially available product from OCI Company, AZDN-30.

[0032] PBS buffer (pH = 6.5) is obtained by diluting the commercially available concentrated solution from Bio-Rad.

[0033] Chitosan (degree of deacetylation ≥80%) is reagent 30168928 from Sinopharm.

[0034] TGA is a commercially available product from TCI Chemicals.

[0035] EDC·HCl is a commercially available product from Alfa Aesar.

[0036] TMPTA is a commercially available product from Wanhua Chemical, WANOLAT® TMPTA.

[0037] Sodium montmorillonite, commercially available product from BYK Additives, CEC = 100 mmol / 100 g.

[0038] Perfluorooctyltriethoxysilane (PFOTES), commercially available product SIT8174.0 from Gelest.

[0039] Gamma-glycidoxypropyltrimethoxysilane, commercially available product Dynasylan® GLYMO from Evonik.

[0040] Dispersant BYK-190, commercially available product BYK®-190 from BYK Additives.

[0041] Coating resin dispersion is an aqueous epoxy emulsion, commercially available product EPI-REZ™ 3510-W-60 from Hexion.

[0042] Iron oxide red inorganic pigment, commercially available product Bayferrox® 110M from Lanxess.

[0043] Polyamide wax paste, commercially available product Ceraflour® 996 from BYK Additives.

[0044] Preparation of thiolated chitosan The preparation process of thiolated chitosan is as follows: Dissolve 100 g of chitosan in 10 L of PBS buffer (pH = 4.5) and stir at 40°C until clear; Add 50 g of TGA and 76 g of EDC-HCl, and react at 40°C for 6 h under nitrogen protection; Dialyze the reaction solution (M W CO=3.5kDa) for 72 h, and freeze-dry to obtain white flocculent thiolated chitosan (thiolation degree 0.9-1.1 mmol / g, molecular weight 9.8±1.2 kDa).

[0045] Preparation Example 1 A pH-responsive polymer microcapsule is prepared as follows: Dissolve 4 g of sodium benzoate and 8 g of sodium molybdate in 50 mL of 60°C deionized water, stir until clear, to obtain solution A; Add 8 g of BTA and 5 g of sodium dodecyl sulfate to 30 mL of anhydrous ethanol, and ultrasonically treat (300 W, 15 min) to obtain translucent colloid B; Drop solution A into colloid B, and high-speed shear emulsify at 6000 rpm for 10 min to obtain a water core dispersion liquid containing BTA micelles (DLS particle size: 152±23 nm); Into a reaction kettle, 2000 mL of toluene, 10 g of sorbitan monooleate (Span-80) were added, stirred and dissolved, 700 g of DMAEMA, 300 g of MAA, 12 g of PETA, 5 g of azobisisobutyronitrile (AIBN) were sequentially added, stirred until uniform, to obtain oil phase C.

[0046] The water core dispersion was slowly injected into oil phase C, and a high-pressure homogenizer (8000 psi) was used for circulation treatment 3 times to obtain a W / O emulsion (microscopic observation of droplet size: 450±80 nm); The temperature was increased to 75±1°C, the stirring rate was 300 rpm, the reaction was carried out for 4 h, and then the temperature was decreased to 25°C at a rate of 2°C / min, and the microcapsules were collected by centrifugation (8000 rpm, 10 min); Toluene was washed 3 times to obtain primary microcapsules; 300 g of primary microcapsules were dispersed in 200 mL of PBS buffer (pH=6.5), 1.5 g of thiolated chitosan was added, and the reaction was carried out at 40°C for 6 h, followed by centrifugal washing, freezing and drying, to obtain 500±60 nm pH-responsive polymer microcapsules.

[0047] Preparation Example 2 A pH-responsive polymer microcapsule, which is different from that obtained in Preparation Example 1, is prepared by replacing 700 g of DMAEMA, 300 g of MAA, and 12 g of PETA with 1000 g of DMAEMA and 18 g of PETA.

[0048] The increase in the amount of PETA is due to the fact that when 1000 g of DMAEMA is used as the only monomer, 12 g of PETA is not enough to form the wall material, and an additional amount of 18 g of PETA is required to form the wall material.

[0049] Preparation Example 3 A pH-responsive polymer microcapsule, which is different from that obtained in Preparation Example 1, is prepared by replacing 700 g of DMAEMA, 300 g of MAA, and 12 g of PETA with 1000 g of DMAEMA and 18 g of PETA.

[0050] Preparation Example 4 A pH-responsive polymer microcapsule, which is different from that obtained in Preparation Example 1, is prepared by replacing 700 g of DMAEMA, 300 g of MAA, and 12 g of PETA with 1000 g of DMAEMA and 18 g of PETA.

[0051] Preparation Example 5 A pH-responsive polymer microcapsule, which is different from that obtained in Preparation Example 1, is prepared by replacing 700 g of DMAEMA, 300 g of MAA, and 12 g of PETA with 1000 g of DMAEMA and 18 g of PETA.

[0052] Preparation Example 6 A pH-responsive polymer microcapsule, which is different from Preparation Example 1 in that the homogenization pressure of the high-pressure homogenizer is 4000 psi after slowly injecting the water core dispersion into the oil phase C, and the obtained pH-responsive polymer microcapsule has a particle size of 800±100 nm.

[0053] Preparation Example 7 A pH-responsive polymer microcapsule, which is different from Preparation Example 1 in that 500 g of DMAEMA and 500 g of MAA are used instead of 700 g of DMAEMA and 300 g of MAA.

[0054] Preparation Example 8 A pH-responsive polymer microcapsule, which is different from Preparation Example 1 in that 900 g of DMAEMA and 100 g of MAA are used instead of 700 g of DMAEMA and 300 g of MAA.

[0055] Preparation Example 9 A pH-responsive polymer microcapsule, which is different from Preparation Example 1 in that 10.5 g of trimethylolpropane triacrylate (TMPTA) is used instead of 12 g of PETA.

[0056] Preparation Example 10 A pH-responsive polymer microcapsule, which is different from Preparation Example 1 in that toluene is washed 3 times, and after obtaining the primary microcapsule, direct freeze-drying is performed to obtain a pH-responsive polymer microcapsule with a particle size of 500±60 nm.

[0057] Preparation Example 11 A pH-responsive polymer microcapsule, which is prepared by the following method: 20 g of BTA and 5 g of sodium dodecyl sulfate are added to 30 mL of anhydrous ethanol, and ultrasonic treatment (300 W, 15 min) is performed to obtain a translucent colloidal B; 50 mL of deionized water is added dropwise to the colloidal B, and high-speed shearing emulsification is performed at 6000 rpm for 10 min to obtain a water core dispersion containing BTA micelles; In a reaction kettle, 2000 mL of toluene and 10 g of sorbitan monooleate (Span-80) are added and stirred to dissolve, and then 700 g of DMAEMA, 300 g of MAA, 12 g of PETA, and 5 g of azobisisobutyronitrile (AIBN) are added in sequence and stirred to uniformity to obtain an oil phase C.

[0058] The water core dispersion is slowly injected into the oil phase C, and the high-pressure homogenizer (8000 psi) is treated for 3 cycles to obtain a W / O type emulsion (microscopic observation of droplet particle size: 450±80 nm); The temperature was increased to 75±1℃, the stirring rate was 300 rpm, the reaction was carried out for 4 h, and then the temperature was decreased to 25℃ at a rate of 2℃ / min, and the microcapsules were collected by centrifugation (8000 rpm, 10 min); The toluene was washed 3 times, and freeze-drying was carried out at -50℃ for 48 h to obtain the pH-responsive polymer microcapsules with a size of 500±60 nm.

[0059] Preparation Example 12 A pH-responsive polymer microcapsule was prepared by the following method: 20 g of sodium molybdate was dissolved in 50 mL of deionized water at 60℃, and stirred until clear to obtain solution A; In a reaction kettle, 2000 mL of toluene and 10 g of sorbitan monooleate (Span-80) were added and stirred to dissolve, and then 700 g of DMAEMA, 300 g of MAA, 12 g of PETA and 5 g of azobisisobutyronitrile (AIBN) were added in sequence and stirred until uniform to obtain oil phase C.

[0060] Solution A was slowly injected into oil phase C, and a high-pressure homogenizer (8000 psi) was used for circulation treatment 3 times to obtain a W / O type emulsion (microscopic observation of droplet size: 450±80 nm); The temperature was increased to 75±1℃, the stirring rate was 300 rpm, the reaction was carried out for 4 h, and then the temperature was decreased to 25℃ at a rate of 2℃ / min, and the microcapsules were collected by centrifugation (8000 rpm, 10 min); The toluene was washed 3 times to obtain the primary microcapsules; 300 g of the primary microcapsules were dispersed in 200 mL of PBS buffer (pH=6.5), 1.5 g of thiolated chitosan was added, and the reaction was carried out at 40℃ for 6 h, followed by centrifugation, washing and freeze-drying to obtain the pH-responsive polymer microcapsules with a size of 500±60 nm.

[0061] Preparation Example 13 A pH-responsive polymer microcapsule was prepared by the following method: 10 g of sodium molybdate was dissolved in 50 mL of deionized water at 60℃, and stirred until clear to obtain solution A; 10 g of BTA and 5 g of sodium dodecyl sulfate were added to 30 mL of anhydrous ethanol, and ultrasonic treatment (300 W, 15 min) was carried out to obtain a translucent colloid B; Solution A was added dropwise to colloid B, and high-speed shearing emulsification was carried out at 6000 rpm for 10 min to obtain a water core dispersion liquid containing BTA micelles (DLS particle size: 152±23 nm); In a reaction kettle, 2000 mL of toluene, 10 g of sorbitan monooleate (Span-80) were added, stirred and dissolved, 700 g of DMAEMA, 300 g of MAA, 12 g of PETA, 5 g of azobisisobutyronitrile (AIBN) were added in turn, stirred until uniform, and an oil phase C was obtained.

[0062] The water core dispersion was slowly injected into the oil phase C, and a high-pressure homogenizer (8000 psi) was used for 3 cycles, and a W / O emulsion was obtained (microscopic observation of droplet size: 450±80 nm); The temperature was raised to 75±1℃, the stirring rate was 300 rpm, the reaction was carried out for 4 h, and then the temperature was gradually lowered to 25℃ (rate 2℃ / min), and the microcapsules were collected by centrifugation (8000 rpm, 10 min); Toluene was washed 3 times to obtain primary microcapsules; 300 g of primary microcapsules were dispersed in 200 mL of PBS buffer (pH=6.5), 1.5 g of thiolated chitosan was added, and the reaction was carried out at 40℃ for 6 h, and then centrifuged, washed and freeze-dried to obtain 500±60 nm pH-responsive polymer microcapsules.

[0063] Preparation Example 14 A fluorosilane modified montmorillonite was prepared by the following method: 100 g of sodium-based montmorillonite (CEC=100 mmol / 100 g) was added to 300 ml of ethanol, refluxed at 80℃ for 1 h, and the ethanol was removed by centrifugation, repeated 3 times to obtain pre-activated montmorillonite; 9 g of PFOTES, 3 g of KH-560 were dissolved in 200 mL of anhydrous ethanol, 20 mL of deionized water and 1.5 mL of glacial acetic acid were added, and the mixture was stirred at 40℃ for 2 h to obtain a hydrolyzed silane solution.

[0064] The activated montmorillonite was added to the hydrolyzed silane solution and stirred at 70℃ under nitrogen protection for 6 h.

[0065] The solid was collected by centrifugation, washed with anhydrous ethanol 5 times, and vacuum dried at 80℃ for 12 h to obtain a modified montmorillonite powder.

[0066] Preparation Example 15 A silane modified montmorillonite was prepared by the following method: 100 g of sodium-based montmorillonite (CEC=100 mmol / 100 g) was added to 300 ml of ethanol, refluxed at 80℃ for 1 h, and the ethanol was removed by centrifugation, repeated 3 times to obtain pre-activated montmorillonite; 12 g of KH-560 was dissolved in 200 mL of anhydrous ethanol, 20 mL of deionized water and 1.5 mL of glacial acetic acid were added, and the mixture was stirred at 40℃ for 2 h to obtain a hydrolyzed silane solution.

[0067] The activated montmorillonite was added into the hydrolyzed silane solution and stirred at 70°C under nitrogen protection for 6 h.

[0068] The solid was collected by centrifugation, washed with anhydrous ethanol for 5 times, and dried at 80°C under vacuum for 12 h to obtain the modified montmorillonite powder.

[0069] Preparation Example 16 A fluorosilane modified montmorillonite was prepared by the following method: 100 g of sodium-based montmorillonite (CEC = 100 mmol / 100 g) was added into 300 ml of ethanol and treated at 80°C for 1 h by reflux. The ethanol was removed by centrifugation, and the operation was repeated for 3 times to obtain the pre-activated montmorillonite; 12 g of PFOTES was dissolved in 200 ml of anhydrous ethanol, and then 20 ml of deionized water and 1.5 ml of glacial acetic acid were added. The mixture was stirred at 40°C for 2 h to obtain the hydrolyzed silane solution.

[0070] The activated montmorillonite was added into the hydrolyzed silane solution and stirred at 70°C under nitrogen protection for 6 h.

[0071] The solid was collected by centrifugation, washed with anhydrous ethanol for 5 times, and dried at 80°C under vacuum for 12 h to obtain the modified montmorillonite powder.

[0072] Example 1 An environment-responsive steel structure nanocomposite anticorrosive coating composition was prepared by the following method: 6.5 kg of fluorosilane modified montmorillonite, 1.2 kg of dispersant BYK-190, and 30 kg of deionized water were added into a basket sand mill. Zirconium oxide beads with a diameter of 0.3 mm were used, and the rotation speed was controlled at 1500 rpm. Water cooling was used to maintain the temperature at no more than 40°C. Sand milling was performed for 20 min to obtain a montmorillonite dispersion slurry with a fineness of less than 20 microns; 100 kg of water-based epoxy emulsion was stirred for 10 min using a planetary stirrer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Then, the pre-dispersed montmorillonite slurry was added, and stirring was continued for 15 min to obtain a resin system composition. XRD detection showed that the interlayer spacing of the montmorillonite remained at 2.86 nm, and FTIR confirmed that the epoxy group characteristic peak was retained by 91%; 2.2 kg of pH-responsive polymer microcapsules were slowly added to the resin system composition, and the material temperature was controlled within the range of 25°C±2°C. An anchor stirrer was used to stir at a speed of 150 rpm for 20 min. HPLC determination of the benzotriazole concentration in the supernatant was less than 0.001 μg / mL, which confirmed that the breakage rate of the pH-responsive polymer microcapsules was less than 1%. An environment-responsive steel structure nanocomposite anticorrosive coating composition was obtained.

[0073] The fluorosilane modified montmorillonite was prepared according to Preparation Example 14.

[0074] The pH-responsive polymer microcapsules were prepared as in Preparation Example 1.

[0075] Comparative Example 1 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 2.

[0076] Comparative Example 2 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 3.

[0077] Comparative Example 3 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 4.

[0078] Example 2 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 5.

[0079] Comparative Example 4 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 6.

[0080] Example 3 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 7.

[0081] Example 4 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 8.

[0082] Example 5 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 9.

[0083] Example 6 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 10.

[0084] Comparative Example 5 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules were prepared as in Preparation Example 11.

[0085] Comparative Example 6 A coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules are prepared in Preparation Example 12.

[0086] Example 7 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the pH-responsive polymer microcapsules are prepared in Preparation Example 13.

[0087] Example 8 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the amount of the fluorosilane-modified montmorillonite prepared in Preparation Example 14 is 0, i.e. no fluorosilane-modified montmorillonite is added.

[0088] Example 9 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the fluorosilane-modified montmorillonite prepared in Preparation Example 14 is replaced by the same amount of the silane-modified montmorillonite prepared in Preparation Example 15.

[0089] Example 10 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the fluorosilane-modified montmorillonite prepared in Preparation Example 14 is replaced by the same amount of the fluorosilane-modified montmorillonite prepared in Preparation Example 16.

[0090] Example 11 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the amounts of raw materials are different, specifically as follows: 5.2 kg of fluorosilane-modified montmorillonite, 1.1 kg of dispersant BYK-190, 30 kg of deionized water, 100 kg of water-based epoxy emulsion, and 2 kg of pH-responsive polymer microcapsules.

[0091] Example 12 An environmentally responsive steel structure nanocomposite anticorrosive coating composition, which differs from Example 1 in that the amounts of raw materials are different, specifically as follows: 7.5 kg of fluorosilane-modified montmorillonite, 1.4 kg of dispersant BYK-190, 30 kg of deionized water, 100 kg of water-based epoxy emulsion, and 2.4 kg of pH-responsive polymer microcapsules.

[0092] The coating compositions of Examples 1-12 and Comparative Examples 1-6 are subjected to the following tests.

[0093] Corrosion propagation width in acidic environment: according to ISO 9227 acidic salt spray test, scratch size 100±5 μm (penetrating the coating to the substrate), corrosion solution is pH=3.0 (using sulfuric acid to adjust pH), 5wt% NaCl solution, the environmental temperature is controlled at 35±2℃, the spraying period is continuous spraying for 240h; the smaller the corrosion width, the better the corrosion resistance.

[0094] Corrosion propagation width in alkaline environment: according to ASTM G31 alkaline immersion + scratch accelerated test, scratch size 100±5 μm (penetrating the coating to the substrate), corrosion solution is pH=12.5 calcium hydroxide solution, temperature control is 50±2℃, immersion time is 168h; the smaller the corrosion width, the better the corrosion resistance.

[0095] Neutral salt spray corrosion test: according to ISO 9227 neutral salt spray test, scratch size 100±5 μm (penetrating the coating to the substrate), salt water is 5% NaCl solution, temperature is 35±2℃, time is 3000h; the smaller the corrosion width, the better the corrosion resistance.

[0096] Bubbling grade after 85℃ / 95%RH damp-heat aging: according to ISO 6270-2 condensed water exposure test, test temperature is 85±2℃, humidity is 95%±3% RH, test time is 1000h, and then the sample is evaluated and graded according to ISO 4628-2 bubbling grade. Grade 0: no bubbling; Grade 1: very few bubbles (≤5 / cm²); Grade 2: moderate bubbles (>5 / cm², diameter <0.5mm).

[0097] The test results are shown in the following table.

[0098] Table 1. Test results of examples 1-12 and comparative examples 1-6

[0099] As can be seen from comparative example 1 and comparative examples 1-2, example 1 exhibits excellent corrosion resistance in both acidic and alkaline environments; comparative example 1 has good corrosion resistance in acidic environment, but poor corrosion resistance in alkaline environment; comparative example 2 has good corrosion resistance in alkaline environment, but poor corrosion resistance in acidic environment; therefore, using DMAEMA-MAA copolymer as wall material in the present application can make the coating react to both acid and alkali in the environment, release the slow-release agent, hinder further corrosion, thereby making the steel structure have more long-acting corrosion resistance in acidic and alkaline environments.

[0100] Comparative Examples 1-2 and Comparative Examples 3-4. The difference between Examples 1-2 and Comparative Examples 3-4 is that the particle size of the pH-responsive polymer microcapsules is different. Due to the difference in the particle size of the pH-responsive polymer microcapsules, the distribution stability of the pH-responsive polymer microcapsules in the coating and the distribution in the coating after spreading with the coating during coating are different, resulting in different response sensitivity of the pH-responsive polymer microcapsules to the acid-base environment. From the test results, it can be seen that Examples 1-2 have good response effect to the acid-base environment, while the response of Comparative Examples 3-4 is obviously poor, so the present application is achieved to respond to the acid-base environment and specifically hinder the occurrence of accelerated failure of the chain coating. The pH-responsive polymer microcapsules in the present application need to use DMAEMA-MAA copolymer as the wall material, and the particle size is controlled to be 300-500 nm.

[0101] Comparative Example 1 and Examples 3-4, the pH-responsive polymer microcapsule wall material in the present application can respond to the acid-base environment, because DMAEMA is easy to swell in acidic environment and MAA is easy to swell in alkaline environment, so the amount ratio of DMAEMA and MAA directly affects the response sensitivity of the wall material to the acid-base environment. From the test results, it can be seen that the corrosion protection effect of Example 1 is better than that of Examples 3-4 in both acidic and alkaline environments, so the molar ratio of DMAEMA and MAA in the wall material preparation in the present application is 7:3, which is more optimal.

[0102] Comparative Example 1 and Example 5, the difference between Example 1 and Example 5 is that the wall material preparation uses different crosslinking agents. The crosslinking agent PETA used in Example 1 can form a network structure in the wall material, reduce the water absorption of the wall material and provide its rupture shear strength, thereby on the one hand it can reduce the breakage loss of the pH-responsive polymer microcapsules mixed into the coating resin dispersion, on the other hand it can also improve the stability of the pH-responsive polymer microcapsules in high humidity environment, avoid the premature failure of the microcapsules in the coating in high speed environment, so the corrosion protection effect of Example 1 is better than that of Example 5 in both acidic and alkaline environments.

[0103] Comparative Example 1 and Example 6, the pH-responsive polymer microcapsules used in Example 1 are further grafted with mercapto chitosan on the surface compared with Example 6. Outdoor steel structures and sample metal plates, although they have been surface polished before being coated with the coating composition, they cannot completely remove rust and polish the surface smooth, and there will still be micron-level surface defects and corrosion sites on the surface. When the coating composition of Example 1 is coated, the mercapto chitosan on the surface of the pH-responsive polymer microcapsules forms Fe-S coordination bonds in the rust micro area, so that the pH-responsive polymer microcapsules are enriched in the active corrosion site, the density of the pH-responsive polymer microcapsules in the rust area is improved, and the corrosion protection effect is improved, so the corrosion protection effect of Example 1 is better than that of Example 6 in both acidic and alkaline environments and neutral salt spray corrosion detection results.

[0104] Comparative Example 1, Comparative Example 5, Comparative Example 6 and Example 7 differ in that the slow-release agent encapsulated in the pH-responsive polymer microcapsules is different. In Comparative Example 6, it is BTA, in Comparative Example 7, it is sodium molybdate, in Example 9, it is BTA and sodium molybdate, and in Example 1, it is BTA, sodium molybdate and sodium benzoate. Example 7 and Example 1 have good corrosion protection in both acidic and alkaline environments. Comparative Example 6 and Comparative Example 7 only have good corrosion protection in one of the two environments, and the corrosion protection in the other environment is significantly weaker.

[0105] For a general corrosion protection coating in the prior art, a single slow-release agent can be selected as in Comparative Examples 6-7, but the problem to be solved by the present application requires that both acidic and alkaline corrosion environments be considered, so BTA and BTA are added in the present application to have a slow-release effect in both acidic and alkaline corrosion environments.

[0106] In addition, by continuing to compare Example 1 and Example 7, it can be seen that the corrosion protection performance of Example 1 is one level higher than that of Example 7 in both acidic and alkaline environments. This is because in an acidic environment, the benzoate salt dissociates into benzoic acid molecules (C6H5COOH), and the carboxyl group of the benzoic acid forms a coordination bond with the Fe atoms on the steel surface. On the one hand, the hydrophobic benzene ring is vertically adsorbed to form a physical barrier layer, reducing the interfacial energy and significantly inhibiting the penetration of Cl⁻ / H2O. On the other hand, the benzoic acid-BTA hydrogen bond network reduces the interfacial energy, guides the [Fe(BTA)2] chelate film to cover the metal corrosion surface, and together forms a high-density composite film, resulting in better corrosion protection. In an alkaline environment, the benzoate anion of the benzoate salt repels OH⁻, continuously passivates the cathode region, and inhibits corrosion. Thus, a synergistic corrosion inhibition system is formed by the benzoate salt, benzotriazole (BTA) and sodium molybdate, which constructs a dense composite protective layer on the metal surface and achieves excellent corrosion protection.

[0107] Comparing Comparative Example 1 and Examples 8-10, it can be seen that fluorosilane-modified montmorillonite can also be added in the present application. The nanosheet layer of montmorillonite has low surface energy and good hydrophobicity. After being mixed and dispersed in the coating, it forces the diffusion path of the corrosive medium to be longer, slowing down the corrosion. Therefore, the corrosion protection performance of Example 1 and Example 10 is significantly better than that of Examples 8-9. At the same time, the corrosion protection performance of Example 1 is also better than that of Example 10. This is because the montmorillonite in Example 1 is modified with a mixture of perfluorooctyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. The perfluorooctyltriethoxysilane grafts introduce a perfluorinated chain to provide superhydrophobicity, and the γ-glycidoxypropyltrimethoxysilane grafts introduce an epoxy agent to enhance the interfacial adhesion. Thus, the anti-bubbling property of the coating during immersion in acidic and alkaline liquids is further improved, thereby further improving the corrosion resistance of the coating.

[0108] In addition, there are other preferred schemes in the present application, such as examples 11-12, which have better scratch corrosion resistance and salt spray corrosion resistance in acid-base environment.

[0109] Pigments are also often added to the coating to enhance the material shielding, coating mechanical properties and identify the integrity of the coating. Therefore, the effect of the coating composition containing inorganic pigments is studied in the present application.

[0110] Example 13 An environmentally responsive steel structure nanocomposite anticorrosive coating composition is prepared as follows: 5.2 kg of fluorosilane modified montmorillonite, 1.1 kg of dispersant BYK-190, 30 kg of red iron oxide inorganic pigment, and 30 kg of deionized water are added to a basket sand mill, zirconium oxide beads with a diameter of 0.3 mm are used, the rotation speed is controlled at 1500 rpm, water cooling is used to maintain the temperature below 40℃, and sand milling is performed for 20 min to obtain a montmorillonite dispersion slurry with a fineness of less than 20 microns; 100 kg of water-based epoxy emulsion is stirred for 10 min using a planetary mixer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Then, the pre-dispersed montmorillonite slurry is added, and stirring is continued for 15 min to obtain a resin system composition. XRD detection shows that the interlayer spacing of the montmorillonite remains 2.86 nm, and FTIR confirms that the epoxy group characteristic peak is retained by 91%; 2 kg of pH-responsive polymer microcapsules are slowly added to the resin system composition, the material temperature is controlled within the range of 25℃±2℃, an anchor stirrer is used to stir at a speed of 150 rpm for 20 min, HPLC measurement of the benzotriazole concentration in the supernatant is less than 0.001 μg / mL, which confirms that the breakage rate of the pH-responsive polymer microcapsules is less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition is obtained.

[0111] The fluorosilane modified montmorillonite is prepared according to Preparation Example 14.

[0112] The pH-responsive polymer microcapsules are prepared according to Preparation Example 1.

[0113] Example 14 An environmentally responsive steel structure nanocomposite anticorrosive coating composition is prepared as follows: 6.5 kg of fluorosilane modified montmorillonite, 1.2 kg of dispersant BYK-190, 33 kg of red iron oxide inorganic pigment, and 30 kg of deionized water are added to a basket sand mill, zirconium oxide beads with a diameter of 0.3 mm are used, the rotation speed is controlled at 1500 rpm, water cooling is used to maintain the temperature below 40℃, and sand milling is performed for 20 min to obtain a montmorillonite dispersion slurry with a fineness of less than 20 microns; The 100 kg water-based epoxy emulsion was stirred for 10 min using a planetary mixer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Then, the pre-dispersed montmorillonite slurry was added, and stirring was continued for 15 min to obtain a resin system composition. XRD detection showed that the interlayer spacing of the montmorillonite remained 2.86 nm, and FTIR confirmed that the epoxy group characteristic peak remained 91%. The 2.2 kg pH-responsive polymer microcapsules were slowly added to the resin system composition, and the material temperature was controlled within the range of 25℃±2℃. An anchor stirrer was used to stir at a speed of 150 rpm for 20 min. HPLC determination of the benzotriazole concentration in the supernatant was less than 0.001 μg / mL, which confirmed that the breakage rate of the pH-responsive polymer microcapsules was less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition was obtained.

[0114] The fluorosilane-modified montmorillonite was prepared according to Preparation Example 14.

[0115] The pH-responsive polymer microcapsules were prepared according to Preparation Example 1.

[0116] Example 15 An environmentally responsive steel structure nanocomposite anticorrosive coating composition was prepared according to the following method: The 7.5 kg fluorosilane-modified montmorillonite, 1.4 kg dispersant BYK-190, 40 kg red iron oxide inorganic pigment, and 30 kg deionized water were added to a basket sand mill. Zirconium oxide beads with a diameter of 0.3 mm were used, and the rotation speed was controlled at 1500 rpm. Water cooling was used to maintain the temperature at no more than 40℃, and sand milling was performed for 20 min to obtain a montmorillonite dispersion slurry with a fineness of less than 20 microns. The 100 kg water-based epoxy emulsion was stirred for 10 min using a planetary mixer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Then, the pre-dispersed montmorillonite slurry was added, and stirring was continued for 15 min to obtain a resin system composition. XRD detection showed that the interlayer spacing of the montmorillonite remained 2.86 nm, and FTIR confirmed that the epoxy group characteristic peak remained 91%. The 2.4 kg pH-responsive polymer microcapsules were slowly added to the resin system composition, and the material temperature was controlled within the range of 25℃±2℃. An anchor stirrer was used to stir at a speed of 150 rpm for 20 min. HPLC determination of the benzotriazole concentration in the supernatant was less than 0.001 μg / mL, which confirmed that the breakage rate of the pH-responsive polymer microcapsules was less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition was obtained.

[0117] The fluorosilane-modified montmorillonite was prepared according to Preparation Example 14.

[0118] The pH-responsive polymer microcapsules are prepared according to Preparation Example 1.

[0119] Example 16 An environmentally responsive steel structure nanocomposite anticorrosive coating composition is prepared according to the following method: 5.2 kg of fluorosilane-modified montmorillonite, 1.1 kg of dispersant BYK-190, 30 kg of red iron oxide inorganic pigment, and 30 kg of deionized water are added to a basket sand mill, zirconium oxide beads with a diameter of 0.3 mm are used, the rotation speed is controlled at 1500 rpm, water cooling is used to maintain the temperature at no more than 40°C, sand milling is performed for 20 min, and a montmorillonite dispersion slurry with a fineness of less than 20 microns is obtained; 100 kg of water-based epoxy emulsion and 1.8 kg of polyamide wax slurry are stirred for 10 min using a planetary stirrer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Subsequently, the pre-dispersed montmorillonite slurry is added, and stirring is continued for 15 min to obtain a resin system composition. XRD detection shows that the interlayer spacing of the montmorillonite remains 2.86 nm, and FTIR confirms that the epoxy group characteristic peak is retained by 91%. 2 kg of pH-responsive polymer microcapsules are slowly added to the resin system composition, the material temperature is controlled within the range of 25°C±2°C, an anchor stirrer is used to stir at a speed of 150 rpm for 20 min, HPLC determination of the benzotriazole concentration in the supernatant is less than 0.001 μg / mL, which confirms that the breakage rate of the pH-responsive polymer microcapsules is less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition is obtained.

[0120] The fluorosilane-modified montmorillonite is prepared according to Preparation Example 14.

[0121] The pH-responsive polymer microcapsules are prepared according to Preparation Example 1.

[0122] Example 17 An environmentally responsive steel structure nanocomposite anticorrosive coating composition is prepared according to the following method: 6.5 kg of fluorosilane-modified montmorillonite, 1.2 kg of dispersant BYK-190, 33 kg of red iron oxide inorganic pigment, and 30 kg of deionized water are added to a basket sand mill, zirconium oxide beads with a diameter of 0.3 mm are used, the rotation speed is controlled at 1500 rpm, water cooling is used to maintain the temperature at no more than 40°C, sand milling is performed for 20 min, and a montmorillonite dispersion slurry with a fineness of less than 20 microns is obtained; 100 kg of water-based epoxy emulsion and 2.2 kg of polyamide wax slurry are stirred for 10 min using a planetary stirrer at a revolution speed of 30 rpm and a rotation speed of 100 rpm; Subsequently, the pre-dispersed montmorillonite slurry was added, and stirring was continued for 15 min to obtain a resin system composition. XRD detection showed that the interlayer spacing of the montmorillonite remained 2.86 nm, and FTIR confirmed that the epoxy group characteristic peak remained 91%. The 2.2 kg of pH-responsive polymer microcapsules were slowly added to the resin system composition, and the material temperature was controlled within the range of 25°C±2°C. An anchor stirring paddle was used to stir at a speed of 150 rpm for 20 min. HPLC determination of the benzotriazole concentration in the supernatant was less than 0.001 μg / mL, which confirmed that the breakage rate of the pH-responsive polymer microcapsules was less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition was obtained.

[0123] The fluorosilane-modified montmorillonite was prepared according to Preparation Example 14.

[0124] The pH-responsive polymer microcapsules were prepared according to Preparation Example 1.

[0125] Example 18 An environmentally responsive steel structure nanocomposite anticorrosive coating composition was prepared according to the following method: The 7.5 kg of fluorosilane-modified montmorillonite, 1.4 kg of dispersant BYK-190, 40 kg of red iron oxide inorganic pigment, and 30 kg of deionized water were added to a basket sand mill. Zirconium oxide beads with a diameter of 0.3 mm were used, and the stirring speed was controlled at 1500 rpm. Water cooling was used to maintain the temperature at no more than 40°C. Sand milling was performed for 20 min to obtain a montmorillonite dispersion slurry with a fineness of less than 20 microns. The 100 kg of water-based epoxy emulsion and 2.6 kg of polyamide wax slurry were stirred using a planetary stirrer at a speed of 30 rpm in revolution and 100 rpm in rotation for 10 min. Subsequently, the pre-dispersed montmorillonite slurry was added, and stirring was continued for 15 min to obtain a resin system composition. XRD detection showed that the interlayer spacing of the montmorillonite remained 2.86 nm, and FTIR confirmed that the epoxy group characteristic peak remained 91%. The 2.4 kg of pH-responsive polymer microcapsules were slowly added to the resin system composition, and the material temperature was controlled within the range of 25°C±2°C. An anchor stirring paddle was used to stir at a speed of 150 rpm for 20 min. HPLC determination of the benzotriazole concentration in the supernatant was less than 0.001 μg / mL, which confirmed that the breakage rate of the pH-responsive polymer microcapsules was less than 1%, and an environmentally responsive steel structure nanocomposite anticorrosive coating composition was obtained.

[0126] The fluorosilane-modified montmorillonite was prepared according to Preparation Example 14.

[0127] The pH-responsive polymer microcapsules were prepared according to Preparation Example 1.

[0128] The examples 13-18 were tested, and the test results are shown in the following table.

[0129] Table 2. Test results table of Examples 13-18

[0130] As can be seen from Comparative Example 1, Examples 11-12 and Examples 13-15, Example 13 is based on Example 11 with the addition of inorganic pigments, Example 14 is based on Comparative Example 1 with the addition of inorganic pigments, and Example 15 is based on Example 12 with the addition of inorganic pigments. The corrosion resistance of Examples 13-15 in acid and alkaline environments is weakened to some extent, which is due to the addition of inorganic pigments which will significantly affect the stability of the distribution of the pH-responsive polymer microcapsules in the coating and the distribution in the wet coating layer during coating.

[0131] To this end, polyamide wax paste is added to the coating composition in the present application, as in Examples 16-18.

[0132] The corrosion resistance and corrosion resistance in acid and alkaline environments of Examples 16-18 are improved compared to Examples 13-15, and also Examples 1, 11-12. The reason is that the polyamide wax paste as a thixotropic thickening agent can form a gel network structure in the coating composition, which produces a yield value for the coating composition, thereby hindering the settling and resolution of the coating composition after mixing. When coating, the coating composition can also temporarily disintegrate the gel network under the action of external force, the viscosity drops sharply, facilitating construction, reducing the loss of pH-responsive polymer microcapsules during the preparation of the coating, and also optimizing the distribution of the pH-responsive polymer microcapsules in the coating composition, thereby enhancing its effect.

[0133] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, as long as the modifications are within the scope of the present application.

Claims

1. An environmentally responsive nanocomposite anti-corrosion coating composition for steel structures, characterized in that, The raw materials include the following parts by weight: 100 parts of coating resin dispersion, pH-responsive polymer microcapsules, 2-2.4 parts, Dispersant 1.1~1.4 parts, 5.2-7.5 parts of fluorosilane-modified montmorillonite, The pH-responsive polymer microcapsules have a particle size of 300-500 nm, are coated with a sustained-release agent, and are grafted with thiolized chitosan (MW=10kDa). The wall material of the pH-responsive polymer microcapsules is a copolymer of dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MAA). Sustained-release agents include benzotriazole (BTA) and sodium molybdate.

2. The environmentally responsive nanocomposite anti-corrosion coating composition for steel structures according to claim 1, characterized in that, The sustained-release agent is a compound of BTA, sodium molybdate, and benzoate in a mass ratio of 1:1:0.

5.

3. The environmentally responsive nanocomposite anti-corrosion coating composition for steel structures according to claim 1, characterized in that, In the copolymer of dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MAA), DMAEMA:MAA = 70:

30.

4. The environmentally responsive nanocomposite anti-corrosion coating composition for steel structures according to claim 1, characterized in that, The crosslinking agent used in the preparation of dimethylaminoethyl methacrylate (DMAEMA)-methacrylic acid (MAA) copolymer is pentaerythritol triacrylate (PETA).

5. The environmentally responsive nanocomposite anti-corrosion coating composition for steel structures according to claim 1, characterized in that, The modifier used in fluorosilane-modified montmorillonite is a compound of perfluorooctyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

6. The environmentally responsive nanocomposite anti-corrosion coating composition for steel structures according to claim 1, characterized in that, It also includes 30-40 parts of inorganic pigments and 1.8-2.6 parts of polyamide wax paste.

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