Preparation method and application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
By introducing Zn-MMT@L-His composite material into waterborne polyurethane coatings, the synergistic effect of zinc ions and histidine was utilized to solve the problem of poor compatibility of nano-montmorillonite in waterborne polyurethane coatings, and the anti-corrosion performance was significantly improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUJIAN NORMAL UNIV
- Filing Date
- 2024-08-07
- Publication Date
- 2026-07-10
AI Technical Summary
The nano-montmorillonite layered structure in waterborne polyurethane coatings tends to aggregate, resulting in poor compatibility with waterborne polyurethane and creating penetration channels for corrosive media, thus affecting the anti-corrosion performance of the coating.
By replacing zinc ions in the interlayer of montmorillonite and chelating them with histidine, a Zn-MMT@L-His composite material is formed. The zinc ions react with OH- generated by corrosion to generate the insoluble Zn(OH)2, which forms a dense protective film with histidine, thereby improving the anti-corrosion performance of the coating.
It enhances the coating's corrosion resistance, effectively preventing the penetration of corrosive media and creating a labyrinth effect, far exceeding the effect of using MMT or histidine alone.
Smart Images
Figure CN118791957B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of anti-corrosion coating technology, specifically relating to the preparation method and application of Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating. Background Technology
[0002] Metal corrosion has a wide-ranging impact on society, including economic losses, safety hazards, environmental pollution, resource waste, and disruptions to production and daily life. It can lead to equipment damage and structural failure, requiring substantial funds for repair and replacement. Furthermore, it can trigger accidents, threatening personnel and property safety, polluting the environment, wasting resources, and hindering the normal operation and development of society. Therefore, preventing and controlling metal corrosion is of paramount importance.
[0003] Waterborne polyurethane uses water instead of organic solvents as the dispersion medium, also known as aqueous polyurethane or water-based polyurethane. It not only possesses some of the important performance characteristics of solvent-based polyurethane, but also has advantages such as non-flammability, non-toxicity, non-polluting properties, energy saving, easy storage, and convenient use, thus attracting much attention and becoming an important direction for development in the polyurethane field today. However, defects such as bubbles and pinholes are inevitably introduced during the curing process, severely affecting the anti-corrosion performance of the coating. Many researchers have modified the coating by adding two-dimensional nanomaterials, which can effectively inhibit the penetration of corrosive ions and improve the barrier performance of the coating. However, these two-dimensional materials still have some limitations in practical applications, such as poor compatibility, severe agglomeration, and galvanic corrosion. Another way to solve this problem is to modify the two-dimensional materials to improve the density of the coating.
[0004] Histidine, a natural bio-based corrosion inhibitor, has been widely used in the field of metal protection due to its unique chemical structure, which allows it to coordinate with numerous metal ions. In metal corrosion prevention, histidine can undergo chelation coordination reactions with metal ions to form a dense protective film, effectively preventing the metal from contacting the corrosive medium and thus slowing down the corrosion rate. Summary of the Invention
[0005] To address the drawbacks of waterborne polyurethane coatings, such as the tendency of nano-montmorillonite layered structures to accumulate moisture, leading to poor compatibility and creating penetration channels for corrosive media, this invention provides a method for preparing and applying a Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating. This method utilizes the substitution of zinc ions with sodium ions between the montmorillonite layers, where the zinc ions act as a corrosion inhibitor, reacting with OH- produced during corrosion. - The reaction generates insoluble Zn(OH)2 on the surface, and histidine undergoes a chelation coordination reaction with metal ions to form a dense protective film. The two have a synergistic effect, thereby improving the anti-corrosion performance of waterborne polyurethane.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing a Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating: Sodium-based montmorillonite (Na-MMT) is ion-exchanged with zinc nitrate hexahydrate to obtain zinc ion-modified montmorillonite (Zn-MMT). Zn-MMT is then immersed in a histidine L-His solution to obtain Zn-MMT@L-His. Finally, Zn-MMT@L-His is uniformly dispersed in a waterborne polyurethane topcoat, and a curing agent is added to prepare the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating. The specific steps are as follows:
[0008] 1) Sodium montmorillonite was dispersed in a zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 60-70℃ for 5.5-6.5 h. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0009] 2) Add Zn-MMT to histidine solution, sonicate for 30-40 min, then soak for 22-26 h to ensure that histidine is uniformly loaded on the surface of Zn-MMT. Finally, after centrifugation, drying and grinding, Zn-MMT@L-His is obtained.
[0010] 3) Add Zn-MMT@L-His to the waterborne polyurethane topcoat and stir to disperse for 60-70 minutes to obtain a dispersion. Then add the curing agent to the dispersion and stir vigorously at room temperature for 15-20 minutes. Then place it in a vacuum drying oven and evacuate to remove air bubbles to obtain the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0011] Further, in step 1), the zinc nitrate hexahydrate solution is prepared as follows: zinc nitrate hexahydrate is dissolved in deionized water at 55~65℃ for 30~40 min, and then mixed at 65~75℃ for 60~70 min to obtain a zinc nitrate hexahydrate solution with a concentration of 0.010~0.011 g / mL.
[0012] Further, in step 2), the concentration of the histidine solution is 0.015~0.07 g / mL.
[0013] Further, in step 2), the molar ratio of Zn-MMT to histidine in the histidine solution is 0.5~1.5:1.
[0014] Further, in step 3), the mass ratio of the waterborne polyurethane topcoat to Zn-MMT@L-His is 1g:5~15mg.
[0015] Further, in step 3), the mass ratio of the waterborne polyurethane topcoat to the curing agent is 0.25~0.33:1.
[0016] Application of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating: The Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating is applied to the substrate using a coating machine and cured at 40℃ for 24~25h to form an anticorrosive coating.
[0017] The significant advantages of this invention are:
[0018] 1. This invention incorporates nanomaterial MMT, creating a labyrinth effect within the coating to effectively increase the diffusion path of corrosive media. Furthermore, the sodium ions of MMT undergo ion exchange with zinc nitrate hexahydrate, introducing zinc ions. These zinc ions act as corrosion inhibitors, reacting with the OH- produced during corrosion. - The reaction generates insoluble Zn(OH)2 on the surface, which improves the corrosion resistance of the coating.
[0019] 2. In this invention, histidine undergoes a chelation coordination reaction with metal ions to form a dense protective film. Therefore, Zn-MMT and histidine have a good synergistic effect on corrosion protection, which is far greater than the effect of MMT modification or histidine alone. Attached Figure Description
[0020] Figure 1 The electrochemical impedance spectroscopy results are as follows: The coatings obtained in Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were immersed in 3.5% NaCl for 1 day.
[0021] Figure 2 The electrochemical impedance spectroscopy results are shown for the coatings obtained in Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 after immersion in 3.5% NaCl for 26 days. Detailed Implementation
[0022] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.
[0023] Example 1
[0024] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0025] (1) Preparation of Zn-MMT@L-His:
[0026] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0027] 1.7g of histidine (L-His) was added to 100ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30min, and soaked for 24h to make histidine uniformly loaded on the surface of Zn-MMT. Finally, after centrifugation, drying and grinding, Zn-MMT@L-His was obtained.
[0028] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0029] Add 5 mg of Zn-MMT@L-His composite material to 1 g of waterborne polyurethane topcoat, stir and disperse for 1 h to obtain a dispersion, then add 0.25 g of curing agent to the above dispersion, stir vigorously at room temperature for 20 min until well dispersed, and then place in a vacuum drying oven at room temperature for 8 min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0030] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0031] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0032] Example 2
[0033] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0034] (1) Preparation of Zn-MMT@L-His:
[0035] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0036] 1.7g of histidine (L-His) was added to 100ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30min, and soaked for 24h to make histidine uniformly loaded on the surface of Zn-MMT. Finally, after centrifugation, drying and grinding, Zn-MMT@L-His was obtained.
[0037] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0038] Add 10mg of Zn-MMT@L-His composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion and stir vigorously at room temperature for 20min until well dispersed, then place it in a vacuum drying oven and vacuum at room temperature for 8min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0039] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0040] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0041] Example 3
[0042] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0043] (1) Preparation of Zn-MMT@L-His:
[0044] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, followed by mixing at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying, and grinding, Zn-MMT was obtained. 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure that histidine was uniformly loaded on the surface of Zn-MMT. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0045] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0046] Add 15mg of Zn-MMT@L-His composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, and then place in a vacuum drying oven at room temperature for 8min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0047] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0048] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0049] Example 4
[0050] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0051] (1) Preparation of Zn-MMT@L-His:
[0052] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0053] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1.5:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0054] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0055] Add 5 mg of Zn-MMT@L-His composite material to 1 g of waterborne polyurethane topcoat, stir and disperse for 1 h to obtain a dispersion, then add 0.25 g of curing agent to the above dispersion, stir vigorously at room temperature for 20 min until well dispersed, and then place it in a vacuum drying oven at room temperature for 8 min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0056] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0057] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0058] Example 5
[0059] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0060] (1) Preparation of Zn-MMT@L-His:
[0061] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0062] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1.5:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0063] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0064] Add 10mg of Zn-MMT@L-His composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, and then place in a vacuum drying oven at room temperature for 8min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0065] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0066] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0067] Example 6
[0068] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0069] (1) Preparation of Zn-MMT@L-His:
[0070] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0071] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT with a molar ratio of 1.5:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0072] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0073] 15 mg of Zn-MMT@L-His composite material was added to 1 g of waterborne polyurethane topcoat and stirred for 1 h to obtain a dispersion. Then, 0.25 g of curing agent was added to the dispersion and stirred vigorously at room temperature for 20 min until well dispersed. The mixture was then placed in a vacuum drying oven and vacuumed at room temperature for 8 min to remove air bubbles, thus obtaining Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0074] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0075] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0076] Example 7
[0077] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0078] (1) Preparation of Zn-MMT@L-His:
[0079] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0080] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT at a molar ratio of 2:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0081] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0082] Add 5 mg of Zn-MMT@L-His composite material to 1 g of waterborne polyurethane topcoat, stir and disperse for 1 h to obtain a dispersion, then add 0.25 g of curing agent to the above dispersion, stir vigorously at room temperature for 20 min until well dispersed, and then place it in a vacuum drying oven at room temperature for 8 min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0083] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosion coating
[0084] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0085] Example 8
[0086] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0087] (1) Preparation of Zn-MMT@L-His:
[0088] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0089] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT at a molar ratio of 2:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0090] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0091] Add 10mg of Zn-MMT@L-His composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, and then place in a vacuum drying oven at room temperature for 8min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0092] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosion coating
[0093] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0094] Example 9
[0095] 1. Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating
[0096] (1) Preparation of Zn-MMT@L-His:
[0097] Zinc nitrate hexahydrate was dissolved in 300 ml of deionized water at 60 °C for half an hour, and then mixed at 70 °C for 1 hour to obtain a zinc nitrate hexahydrate solution. Sodium montmorillonite was dispersed in the zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 65 °C for 6 hours. After centrifugation, drying and grinding, Zn-MMT was obtained.
[0098] 1.7 g of histidine (L-His) was added to a beaker containing 100 ml of deionized water and stirred until completely dissolved to obtain a histidine solution. Zn-MMT at a molar ratio of 2:1 to histidine was added to the above histidine solution, ultrasonically dispersed for 30 min, and soaked for 24 h to ensure histidine was uniformly loaded onto the Zn-MMT surface. Finally, after centrifugation, drying, and grinding, Zn-MMT@L-His was obtained.
[0099] (2) Preparation of Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating:
[0100] Add 15mg of Zn-MMT@L-His composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, and then place in a vacuum drying oven at room temperature for 8min to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
[0101] 2. Application of Zn-MMT@L-His modified waterborne polyurethane anticorrosion coating
[0102] The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to a tinplate substrate using a coating machine. The tinplate substrate was then placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT@L-His / WPU coating on the tinplate substrate.
[0103] Comparative Example 1
[0104] Preparation of pure water-based polyurethane coating
[0105] (1) Weigh 1g of waterborne polyurethane topcoat, add 0.25g of curing agent, stir at high speed for 1h50min until well dispersed, and then put it in a vacuum drying oven at room temperature for 8min to remove air bubbles, and obtain pure waterborne polyurethane coating.
[0106] (2) Apply pure water-based polyurethane coating to the tinplate substrate using a coating machine. Place the tinplate substrate in a hot air drying oven and cure at 40°C for 24 hours to successfully form a WPU coating on the tinplate substrate.
[0107] Comparative Example 2
[0108] Preparation of Zn-MMT / WPU coating
[0109] (1) Add 10mg of Zn-MMT composite material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, then put it in a vacuum drying oven and vacuum at room temperature for 8min to remove bubbles, to obtain Zn-MMT modified waterborne polyurethane anticorrosive coating.
[0110] (2) The Zn-MMT modified waterborne polyurethane anti-corrosion coating was applied to the tinplate substrate using a coating machine. The tinplate substrate was placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming a Zn-MMT / WPU coating on the tinplate substrate.
[0111] Comparative Example 3
[0112] Preparation of L-His / WPU coating
[0113] (1) Add 10mg of L-His material to 1g of waterborne polyurethane topcoat, stir and disperse for 1h to obtain a dispersion, then add 0.25g of curing agent to the above dispersion, stir vigorously at room temperature for 20min until well dispersed, and then put it into a vacuum drying oven at room temperature for 8min to remove bubbles to obtain L-His modified waterborne polyurethane anti-corrosion coating.
[0114] (3) The L-His modified waterborne polyurethane anti-corrosion coating was applied to the tinplate substrate using a coating machine. The tinplate substrate was placed in a hot air drying oven and cured at 40°C for 24 hours, successfully forming an L-His / WPU coating on the tinplate substrate.
[0115] Experimental Example
[0116] Open circuit potential (OCP) is widely considered an effective method for evaluating the formation of protective corrosion products. Furthermore, OCP measurement reflects the stability of the thin film in a corrosive environment.
[0117] The corrosion resistance of the coatings was evaluated by measuring the open-circuit potential in a 3.5% NaCl solution. The measurement results are shown in Table 1. The OCP value of Example 2 was more positive than that of the comparative coating. This indicates that the waterborne polyurethane coating prepared in Example 2 of this invention provides the most effective protection in corrosive environments. Therefore, the following studies will use Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 for comparison.
[0118] The coatings obtained in Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were immersed in 3.5% NaCl solution for 1 day and 26 days, respectively. The electrochemical impedance spectroscopy results are as follows: Figure 1 , 2 As shown. Example 2 uses Zn-MMT@L-His material as filler. Compared with Comparative Examples 2 and 3, which added Zn-MMT@ and Zn-MMT@L-His in the same proportion, the coating obtained in Example 2 has a higher low-frequency impedance value. After soaking for 1 day, the impedance modulus increased by about 2 orders of magnitude. It also maintained a very high low-frequency impedance value after 26 days. It is also much higher than the impedance value of the pure water-based polyurethane coating in Comparative Example 1. This shows that the coating formed on the material by Zn-MMT@L-His / WPU prepared in this invention has excellent corrosion resistance in corrosive environments.
[0119] Table 1. Test results of open circuit potential of coating
[0120] sample OCP / vs AgCl sample OCP / vs AgCl Example 1 -0.2803 Example 8 -0.3308 Example 2 0.0013 Example 9 -0.4075 Example 3 -0.2626 Example 10 -0.5916 Example 4 -0.5393 Comparative Example 1 -0.7624 Example 5 -0.5151 Comparative Example 2 -0.6132 Example 6 -0.4912 Comparative Example 3 -0.6624 Example 7 -0.3852
Claims
1. A method for preparing Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating, characterized in that, Zinc-modified montmorillonite (Zn-MMT) was obtained by ion exchange of sodium-based montmorillonite (Na-MMT) with zinc nitrate hexahydrate. Zn-MMT was then immersed in a histidine solution to uniformly load L-His histidine onto the Zn-MMT surface, resulting in Zn-MMT@L-His. Finally, Zn-MMT@L-His was uniformly dispersed in a waterborne polyurethane topcoat, and a curing agent was added to prepare a Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating.
2. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 1, characterized in that, The specific steps are as follows: 1) Sodium montmorillonite was dispersed in a zinc nitrate hexahydrate solution, and the resulting suspension was reacted at 60-70℃ for 5.5-6.5 h. After centrifugation, drying and grinding, Zn-MMT was obtained. 2) Add Zn-MMT to histidine solution, sonicate for 30-40 min, then soak for 22-26 h to ensure that histidine is uniformly loaded on the surface of Zn-MMT. Finally, after centrifugation, drying and grinding, Zn-MMT@L-His is obtained. 3) Add Zn-MMT@L-His to the waterborne polyurethane topcoat, stir and disperse for 60~70min to obtain a dispersion, then add the curing agent to the dispersion, stir at room temperature for 15~20min, and then place it in a vacuum drying oven to remove air bubbles to obtain Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating.
3. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 2, characterized in that, In step 1), the zinc nitrate hexahydrate solution is prepared as follows: zinc nitrate hexahydrate is dissolved in deionized water at 55-65℃ for 30-40 min, and then mixed at 65-75℃ for 60-70 min to obtain a zinc nitrate hexahydrate solution with a concentration of 0.010-0.011 g / mL.
4. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 2, characterized in that, In step 2), the concentration of the histidine solution is 0.015~0.07 g / mL.
5. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 2, characterized in that, In step 2), the molar ratio of Zn-MMT to histidine in the histidine solution is 0.5~1.5:
1.
6. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 2, characterized in that, In step 3), the mass ratio of the waterborne polyurethane topcoat to Zn-MMT@L-His is 1g:5~15mg.
7. The preparation method of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating according to claim 2, characterized in that, In step 3), the mass ratio of the waterborne polyurethane topcoat to the curing agent is 0.25~0.33:
1.
8. The Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating obtained by the preparation method according to any one of claims 1 to 7.
9. The application of the Zn-MMT@L-His modified waterborne polyurethane anticorrosive coating obtained by the preparation method according to any one of claims 1 to 7, characterized in that, The Zn-MMT@L-His modified waterborne polyurethane anti-corrosion coating was applied to the substrate using a coating machine and cured at 40°C for 24-25 hours to form an anti-corrosion coating.