A composite anti-corrosion coating for steel grating and its preparation method

Abstract

This invention discloses a method for preparing a composite anti-corrosion coating for steel grating, comprising the following steps: S1: spinning a self-healing polymer solution to form hollow fibers with a hollow structure; S2: immersing the fibers in a corrosion inhibitor solution using ethanol as a solvent, allowing the corrosion inhibitor solution to fill the interior of the hollow fibers, followed by end-sealing treatment; S3: heat treatment to form hollow fibers with a porous structure; S4: coating the surface of the fibers with a pH-responsive polymer; S5: mixing the polymer with an anti-corrosion coating, then spraying the mixture onto the surface of the steel grating, and curing to obtain the composite anti-corrosion coating. This method not only achieves the self-healing function of the coating and enhances its corrosion resistance in acidic environments, but also improves the durability and adaptability of the coating through an intelligent response mechanism, meeting the requirements for long-term stable use in highly corrosive environments such as marine and chemical industries.

Description

Technical Field

[0001] This invention relates to the technical field of anti-corrosion coatings, and more particularly to a composite anti-corrosion coating for steel grating and its preparation method. Background Technology

[0002] Steel grating, a commonly used industrial material, is widely applied in construction, chemical, and marine industries. However, during use, steel grating is susceptible to corrosion, especially in environments with high humidity, high salinity, and strong chemical corrosiveness, significantly shortening its service life. In acidic environments, the corrosion rate accelerates further, drastically reducing the protective performance of traditional anti-corrosion coatings. Traditional anti-corrosion coatings primarily prevent corrosion of metal surfaces through physical isolation and chemical protection, but these coatings are prone to cracking or damage under mechanical impact or chemical erosion, leading to coating failure. Furthermore, traditional coatings lack self-healing capabilities; once damaged, corrosive media rapidly penetrate the metal surface, further exacerbating corrosion. Therefore, developing a novel anti-corrosion coating that effectively addresses these issues to improve the corrosion resistance and service life of steel grating in harsh environments such as acidic conditions is of significant practical importance. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for preparing a composite anti-corrosion coating for steel grating, so as to solve the technical problems of traditional anti-corrosion coatings being prone to failure in highly corrosive environments, lacking self-healing function, and having insufficient mechanical properties.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a composite anti-corrosion coating for steel grating, the method comprising the following steps:

[0006] S1: A self-healing polymer solution is used for spinning to form hollow fibers with a hollow structure; the length of the hollow fibers is 5-10 mm, and the pore size is 1-10 μm. Step S1 of this application prepares fibers with a hollow structure by using a self-healing polymer solution for spinning. These hollow fibers not only possess excellent mechanical properties, enhancing the impact resistance and abrasion resistance of the coating, but their internal hollow structure also serves as a storage space for corrosion inhibitors and antibacterial agents, providing a foundation for subsequent self-healing functions. The reasonable design of the hollow fiber's length and pore size ensures both fiber strength and the uniform distribution and effective release of the internal filling material. When the coating is damaged, the repair material inside the hollow fiber can be activated, thereby realizing the self-healing function of the coating and significantly improving its durability and stability.

[0007] S2: The hollow fibers obtained in step S1 are immersed in a corrosion inhibitor solution using ethanol as a solvent, allowing the corrosion inhibitor solution to fill the interior of the hollow fibers. Then, the hollow fibers are end-sealed. In step S2 of this application, the hollow fibers are immersed in a corrosion inhibitor solution using ethanol as a solvent, ensuring that the corrosion inhibitor solution fully fills the interior of the hollow fibers. Ethanol, as a solvent, has good solubility and volatility, and can rapidly evaporate during subsequent heat treatment, forming a porous structure that provides space for the storage and release of the corrosion inhibitor. The end-sealing treatment ensures the stability of the corrosion inhibitor inside the hollow fibers, preventing premature loss during coating preparation and storage. This design allows the corrosion inhibitor to be uniformly released through the porous structure of the hollow fibers when the coating is damaged, forming a protective film that effectively inhibits corrosion of the metal surface, thereby significantly improving the anti-corrosion performance of the coating.

[0008] S3: The hollow fibers filled and sealed in step S2 are subjected to heat treatment, causing ethanol to evaporate from the fiber surface, forming hollow fibers with a porous structure. In this application, step S3 involves heat treatment, during which ethanol evaporates from the fiber surface, resulting in a porous structure inside the hollow fibers. This porous structure not only provides more storage space for the corrosion inhibitor but also promotes its rapid release when needed. Simultaneously, the heat treatment process enhances the structural stability of the hollow fibers, enabling them to maintain good performance during subsequent coating preparation and use.

[0009] S4: Coating the surface of the hollow fiber after heat treatment in step S3 with a layer of pH-responsive polymer; Step S4 of this application coats the surface of the hollow fiber with a layer of pH-responsive polymer, providing a smart response mechanism for the coating. This polymer can rapidly degrade in acidic environments, releasing corrosion inhibitors and antibacterial agents stored inside the hollow fiber. When the coating is eroded by corrosive media and the local environment becomes acidic, the pH-responsive polymer automatically responds, activating the self-healing process to achieve timely repair of damaged areas. This smart response mechanism not only improves the self-healing efficiency of the coating but also allows it to self-regulate according to the actual corrosive environment, thereby significantly improving the durability and stability of the coating. Simultaneously, the coating with the pH-responsive polymer also improves the surface properties of the hollow fiber, enhances its adhesion to the anti-corrosion coating, and improves the overall performance of the coating.

[0010] S5: The hollow fibers coated in step S4 are mixed with the anti-corrosion coating, then sprayed onto the surface of the steel grating and cured to prepare the composite anti-corrosion coating. The composite anti-corrosion coating prepared in step S5 of this application not only retains the excellent properties of traditional anti-corrosion coatings, such as good adhesion, wear resistance, and weather resistance, but also possesses self-healing capabilities through the addition of hollow fibers. The hollow fibers are uniformly distributed in the coating, enabling them to respond quickly and release repair materials when the coating is damaged, achieving self-repair. The curing process ensures the structural stability and mechanical properties of the coating, allowing it to withstand various environmental factors in actual use. The resulting composite anti-corrosion coating exhibits excellent comprehensive performance, effectively extending the service life of the steel grating and reducing maintenance costs.

[0011] As a preferred technical solution, the self-healing polymer solution comprises the following raw materials in parts by weight: 10-30 parts of disulfide-modified polyurethane, 20-40 parts of epoxy resin, 5-15 parts of nano zinc oxide, 1-10 parts of corrosion inhibitor, 1-10 parts of antibacterial agent, 1-5 parts of plasticizer, and 1-5 parts of stabilizer.

[0012] As a preferred technical solution, the disulfide-modified polyurethane is obtained by reacting a polyurethane prepolymer containing at least two isocyanate end groups with N,N'-bis(2-hydroxyethyl)dithioacetamide.

[0013] The parameters for the spinning operation are: spinning voltage 15-25kV, spinning distance 15-25cm, and flow rate 0.5-1.5mL / h.

[0014] As a preferred technical solution, the corrosion inhibitor also includes an amine curing agent, a corrosion inhibitor, and an organic antibacterial agent.

[0015] As a preferred technical solution, the amine curing agent is at least one of phenolic amine curing agents, alicyclic amine curing agents, and fatty amine curing agents.

[0016] As a preferred technical solution, the corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, and 2-mercaptobenzothiazole.

[0017] As a preferred technical solution, the organic antibacterial agent is composed of isothiazolinone and polyhexamethylene guanidine.

[0018] As a preferred technical solution, the end-sealing treatment involves sealing both ends of the hollow fiber with a chemical end-sealing agent, wherein the chemical end-sealing agent is a silane coupling agent and / or an epoxy resin end-sealing agent.

[0019] As a preferred technical solution, the pH-responsive polymer is at least one of polymethacrylic acid, polyacrylic acid, and methacrylic acid-ethyl acrylate copolymer (1:1).

[0020] The present invention also provides a composite anti-corrosion coating for steel grating, wherein the anti-corrosion coating is prepared by the method described above for preparing a composite anti-corrosion coating for steel grating.

[0021] The beneficial effects of this invention are:

[0022] This invention discloses a method for preparing a composite anti-corrosion coating for steel grating. Through innovative methods of filling the hollow fibers with a corrosion inhibitor and performing end-sealing treatment, and coating the fiber surface with a pH-responsive polymer, the coating not only achieves self-healing capabilities but also intelligent response in acidic environments. This design not only enhances the coating's corrosion resistance but also maintains its mechanical properties and stability, helping to extend the service life of the steel grating and reduce maintenance costs.

[0023] In summary, the composite anti-corrosion coating for steel grating of the present invention not only has excellent anti-corrosion performance and self-healing ability, but also improves the durability and adaptability of the coating through an intelligent response mechanism, which can meet the long-term stable use requirements in highly corrosive environments such as marine and chemical industries. Detailed Implementation

[0024] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0025] The method for preparing the composite anti-corrosion coating of steel grating in this embodiment includes the following steps:

[0026] S1: A self-healing polymer solution is used for spinning to form hollow fibers with a hollow structure. The self-healing polymer solution is prepared from the following raw materials in parts by weight: 10 parts disulfide-modified polyurethane, 20 parts epoxy resin, 5 parts nano zinc oxide, 2 parts corrosion inhibitor (benzotriazole), 2.5 parts antibacterial agent (silver ion antibacterial agent), 1.5 parts plasticizer (dibutyl phthalate), and 1 part stabilizer (polyvinyl alcohol). The disulfide-modified polyurethane is obtained by reacting a polyurethane prepolymer containing at least two isocyanate end groups with N,N'-di(2-hydroxyethyl)dithioacetamide; specifically, the polyurethane prepolymer and N,N'-di(2-hydroxyethyl)dithioacetamide are mixed at a molar ratio of 1:1.2 and reacted at 80°C for 4 hours to obtain the disulfide-modified polyurethane. The spinning parameters are set as follows: spinning voltage 15kV, spinning distance 20cm, and flow rate 1.2mL / h. The above spinning process can form hollow fibers with a length of 10 mm and a pore size of 6 μm.

[0027] S2: The hollow fibers obtained in step S1 are immersed in a corrosion inhibitor solution using ethanol as a solvent, ensuring the solution fully fills the interior of the hollow fibers. The corrosion inhibitor solution contains an amine curing agent (phenolic amine curing agent), a corrosion inhibitor (benzotriazole), and an organic antibacterial agent (composed of isothiazolinone and polyhexamethylene guanidine in a mass ratio of 2:3) in a 5:3:1 ratio. After immersion, both ends of the hollow fibers are sealed with a chemical end-capping agent (epoxy resin end-capping agent) to ensure the stability of the corrosion inhibitor solution within the fibers and prevent premature loss during subsequent processing.

[0028] S3: The hollow fibers filled and sealed in step S2 are placed in a nitrogen atmosphere furnace for heat treatment, with the temperature controlled at 70°C and the treatment time at 3 hours. During the heat treatment, ethanol evaporates from the fiber surface, while amine curing agents (phenolic amine curing agents), corrosion inhibitors (benzotriazole), and organic antibacterial agents (composed of isothiazolinone and polyhexamethylene guanidine) adhere to the inner surface of the hollow fibers, forming hollow fibers with a porous structure.

[0029] S4: Uniformly coat the surface of the hollow fiber after heat treatment in step S3 with a layer of pH-responsive polymer. The specific coating method is as follows: Immerse the hollow fiber in a mixed solution composed of pH-responsive polymer (polymethacrylic acid) and solvent tetrahydrofuran, with a solution concentration of 15wt%, for 60 minutes, and then dry it at 70°C.

[0030] S5: The hollow fibers coated in step S4 are mixed with the anti-corrosion coating at a mass ratio of 1:20. The anti-corrosion coating is prepared by mixing component A and component B at a weight ratio of 5:2. Component A consists of the following raw materials in parts by weight: 25 parts epoxy resin, 15 parts nano-titanium dioxide powder, 5 parts graphene oxide, 5 parts montmorillonite, 7 parts lignosulfonate, 0.4 parts water-soluble silicone oil, 0.8 parts polyurethane, and 0.2 parts organobentonite. Component B consists of ketimide and aluminum chloride in a weight ratio of 5:1. The mixed coating is sprayed onto the surface of the steel grating. After spraying, the steel grating is placed in a curing device, and the temperature is controlled at 120°C for 6 hours to allow the coating to fully cure, thus obtaining the composite anti-corrosion coating for the steel grating. Example 2

[0031] The method for preparing the composite anti-corrosion coating of steel grating in this embodiment includes the following steps:

[0032] S1: A self-healing polymer solution is used for spinning to form hollow fibers with a hollow structure. The self-healing polymer solution is prepared from the following raw materials in parts by weight: 20 parts disulfide-modified polyurethane, 30 parts epoxy resin, 10 parts nano zinc oxide, 6 parts corrosion inhibitor (benzotriazole), 5.5 parts antibacterial agent (silver ion antibacterial agent), 2.5 parts plasticizer (dibutyl phthalate), and 3 parts stabilizer (polyvinyl alcohol). The disulfide-modified polyurethane is the same as in Example 1. The spinning parameters are the same as in Example 1. Hollow fibers with a length of 10 mm and a pore size of 6 μm can be formed through the above spinning operation.

[0033] S2: Immerse the hollow fibers obtained in step S1 in a corrosion inhibitor solution using ethanol as the solvent, ensuring the solution fully fills the interior of the hollow fibers. The corrosion inhibitor solution contains an amine curing agent (alicyclic amine curing agent), a corrosion inhibitor (methylbenzotriazole), and an organic antibacterial agent (same as in Example 1) in a mass ratio of 5:3:2. After immersion, seal both ends of the hollow fibers with a chemical end-capping agent (epoxy resin end-capping agent) to ensure the stability of the corrosion inhibitor solution within the fibers and prevent premature loss during subsequent processing.

[0034] S3: The hollow fibers filled and sealed in step S2 are placed in a nitrogen atmosphere furnace for heat treatment, with the temperature controlled at 70°C and the treatment time at 3 hours. During the heat treatment, ethanol evaporates from the fiber surface, while amine curing agents (alicyclic amine curing agents), corrosion inhibitors (methylbenzotriazole), and organic antibacterial agents adhere to the inner surface of the hollow fibers, forming hollow fibers with a porous structure.

[0035] S4: Uniformly coat the surface of the hollow fiber after heat treatment in step S3 with a layer of pH-responsive polymer. The specific coating method is as follows: Immerse the hollow fiber in a mixed solution composed of pH-responsive polymer (polyacrylic acid) and solvent tetrahydrofuran, with a solution concentration of 15wt%, for 60 minutes, and then dry it at 70°C.

[0036] S5: Mix the hollow fibers coated in step S4 with the anti-corrosion coating at a mass ratio of 1:15. The anti-corrosion coating is the same as in Example 1. Spray the mixed coating onto the surface of the steel grating. After spraying, place the steel grating in a curing device, control the temperature at 120°C, and cure for 6 hours to allow the coating to fully cure, thus obtaining the composite anti-corrosion coating for the steel grating. Example 3

[0037] The method for preparing the composite anti-corrosion coating of steel grating in this embodiment includes the following steps:

[0038] S1: A self-healing polymer solution is used for spinning to form hollow fibers with a hollow structure. The self-healing polymer solution is prepared from the following raw materials in parts by weight: 30 parts disulfide-modified polyurethane, 40 parts epoxy resin, 15 parts nano zinc oxide, 10 parts corrosion inhibitor (benzotriazole), 8 parts antibacterial agent (silver ion antibacterial agent), 3.5 parts plasticizer (dibutyl phthalate), and 5 parts stabilizer (polyvinyl alcohol). The disulfide-modified polyurethane is the same as in Example 1. The spinning parameters are the same as in Example 1. Hollow fibers with a length of 10 mm and a pore size of 6 μm can be formed through the above spinning operation.

[0039] S2: The hollow fibers obtained in step S1 are immersed in a corrosion inhibitor solution using ethanol as the solvent, ensuring the solution fully fills the interior of the hollow fibers. The corrosion inhibitor solution contains an amine curing agent (aliphatic amine curing agent), a corrosion inhibitor (2-mercaptobenzothiazole), and an organic antibacterial agent (same as in Example 1) in a mass ratio of 7:2:3. After immersion, both ends of the hollow fibers are sealed with a chemical end-capping agent (epoxy resin end-capping agent) to ensure the stability of the corrosion inhibitor solution within the fibers and prevent premature loss during subsequent processing.

[0040] S3: The hollow fibers filled and sealed in step S2 are placed in a nitrogen atmosphere furnace for heat treatment, with the temperature controlled at 70℃ and the treatment time at 3 hours. During the heat treatment, ethanol evaporates from the fiber surface, while amine curing agents (aliphatic amine curing agents), corrosion inhibitors (2-mercaptobenzothiazole), and organic antibacterial agents adhere to the inner surface of the hollow fibers, forming hollow fibers with a porous structure.

[0041] S4: Uniformly coat the surface of the hollow fiber after heat treatment in step S3 with a layer of pH-responsive polymer. The specific coating method is as follows: Immerse the hollow fiber in a mixed solution composed of pH-responsive polymer (methacrylic acid-ethyl acrylate copolymer (1:1)) and solvent tetrahydrofuran, with a solution concentration of 15wt%, for 60 minutes, and then dry at 70°C.

[0042] S5: Mix the hollow fibers coated in step S4 with the anti-corrosion coating at a mass ratio of 3:40. The anti-corrosion coating is the same as in Example 1. Spray the mixed coating onto the surface of the steel grating. After spraying, place the steel grating in a curing device, control the temperature at 120°C, and cure for 6 hours to allow the coating to fully cure, thus obtaining the composite anti-corrosion coating for the steel grating.

[0043] Comparative Example 1

[0044] The preparation method of the composite anti-corrosion coating for steel grating in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in step S1 of the preparation method of this comparative example, conventional polyurethane is used instead of disulfide bond modified polyurethane.

[0045] Comparative Example 2

[0046] The preparation method of the composite anti-corrosion coating for steel grating in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that steps S2 to S4 are not performed in the preparation method of this comparative example.

[0047] The composite anti-corrosion coatings for steel gratings prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the performance results are shown in Table 1.

[0048] Among them, the salt spray resistance test: According to GB / T 1771 "Determination of resistance to neutral salt spray of paints and varnishes", the prepared steel grating composite anti-corrosion coating sample was cut into 150mm×70mm test pieces. The surface of the test pieces was gently sanded with sandpaper to remove impurities, and then wiped clean with anhydrous ethanol. The test pieces were placed in the salt spray test chamber, ensuring that the surface of the test pieces was facing upward and at an angle of 15° to 30° with the vertical direction. The test chamber temperature was set to 35℃, and the salt solution concentration was 5% (mass fraction) NaCl solution for the salt spray test.

[0049] Scratch Repair Rate Test: A custom test method was used. The prepared steel grating composite anti-corrosion coating sample was cut into 100mm×100mm pieces. A scratch with a depth of approximately 0.5mm was made on the surface of the piece using a scratching tool, ensuring that the scratch penetrated the coating but did not damage the substrate. The scratched piece was placed in an acidic environment (pH 4) and the ambient temperature was maintained at 25℃±2℃. After 24 hours, the piece was removed, and the repair status of the scratch was observed under a microscope. The repair area was recorded, and the scratch repair rate was calculated using the formula: Repair rate (%) = (Repair area / Total scratch area) × 100%.

[0050] Abrasion Resistance Test: According to GB / T 1768 "Determination of Abrasion Resistance of Coating Films", the prepared steel grating composite anti-corrosion coating sample was cut into 100mm×100mm test pieces. The surface of the test pieces was gently sanded with sandpaper to remove impurities, and then wiped clean with anhydrous ethanol. The test pieces were fixed on the abrasion testing machine, ensuring the surface was flat. The abrasion speed of the abrasion testing machine was set to 1000 rpm, and the rotation speed was 60 rpm. The abrasion test was then started. After the test, the wear condition of the coating was observed under a microscope, and the wear depth was recorded to evaluate the abrasion resistance of the coating.

[0051] Impact resistance test: According to GB / T 1732 "Determination of Impact Resistance of Coating Film", the prepared steel grating composite anti-corrosion coating sample was cut into 50mm×50mm test pieces. The surface of the test pieces was gently sanded with sandpaper to remove impurities, and then wiped clean with anhydrous ethanol. The test pieces were placed in the impact testing machine, ensuring that the surface of the test pieces was flat, and the impact testing machine was started to conduct the impact test on the test pieces.

[0052] Table 1

[0053]

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a composite anti-corrosion coating for steel grating, characterized in that, The preparation method includes the following steps: S1: A self-healing polymer solution is used for spinning to form hollow fibers with a hollow structure; S2: Immerse the hollow fiber obtained in step S1 in a corrosion inhibitor solution with ethanol as the solvent, so that the corrosion inhibitor solution fills the interior of the hollow fiber, and then perform end sealing treatment on the hollow fiber. S3: Heat-treat the hollow fibers after filling and sealing in step S2 to allow ethanol to evaporate from the fiber surface, forming hollow fibers with a porous structure. S4: Coat the surface of the heat-treated hollow fiber in step S3 with a layer of pH-responsive polymer; S5: Mix the hollow fiber coated in step S4 with the anti-corrosion coating, then spray it onto the surface of the steel grating and cure it to prepare the composite anti-corrosion coating. The self-healing polymer solution comprises the following raw materials in parts by weight: 10-30 parts of disulfide-modified polyurethane, 20-40 parts of epoxy resin, 5-15 parts of nano zinc oxide, 1-10 parts of corrosion inhibitor, 1-10 parts of antibacterial agent, 1-5 parts of plasticizer, and 1-5 parts of stabilizer; the corrosion inhibitor also includes an amine curing agent, a corrosion inhibitor, and an organic antibacterial agent; the corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, and 2-mercaptobenzothiazole; the pH-responsive polymer is at least one of polymethacrylic acid, polyacrylic acid, and methacrylic acid-ethyl acrylate copolymer (1:1).

2. The method for preparing the composite anti-corrosion coating for steel grating as described in claim 1, characterized in that, The disulfide-modified polyurethane is obtained by reacting a polyurethane prepolymer containing at least two isocyanate end groups with N,N'-bis(2-hydroxyethyl)dithioacetamide.

3. The method for preparing the composite anti-corrosion coating for steel grating as described in claim 1, characterized in that, The amine curing agent is at least one of phenolic amine curing agents, alicyclic amine curing agents, and fatty amine curing agents.

4. The method for preparing the composite anti-corrosion coating for steel grating as described in claim 1, characterized in that, The organic antibacterial agent is composed of isothiazolinone and polyhexamethylene guanidine.

5. The method for preparing the composite anti-corrosion coating for steel grating as described in claim 1, characterized in that, The end-sealing treatment involves sealing both ends of the hollow fiber with a chemical end-sealing agent, which is a silane coupling agent and / or an epoxy resin end-sealing agent.

6. A composite anti-corrosion coating for steel grating, characterized in that, The anti-corrosion coating is prepared using the method described in any one of claims 1 to 5 for preparing a composite anti-corrosion coating for steel grating.

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