Room-temperature curing super-hydrophobic anticorrosive coating and preparation method thereof

Abstract

The invention belongs to the technical field of hydrophobic anticorrosive coatings, and particularly relates to a room-temperature curing super-hydrophobic anticorrosive coating and a preparation method thereof. The preparation method comprises the following steps: taking micron particles and nano particles as raw materials, immersing the raw materials into a siloxane amination reagent solution, carrying out amination modification on the micron particles and the nano particles, then adding an epoxy resin system, and carrying out nucleophilic ring opening to form a composite particle solution; the surface of a base material is coated with the composite particle solution, room-temperature curing is conducted, a base layer is constructed and formed, the base layer is coated with chain isocyanate, the isocyanate and the composite particles are subjected to room-temperature crosslinking, a modification layer is formed, in-situ curing is conducted on a micro-nano coarse structure in the crosslinking process, and the super-hydrophobic anti-corrosion coating is obtained. Based on a cross-scale micro-nano composite structure design and an isocyanate directional grafting technology, micron particles and a nanophase are subjected to gradient compounding to construct a three-dimensional interlocking network, and in-situ cross-linking reaction of isocyanate and epoxy resin amido is combined, so that the room-temperature curing super-hydrophobic anticorrosive coating universal for various base materials is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrophobic anti-corrosion coatings, and particularly relates to a room-temperature curable superhydrophobic anti-corrosion coating and a preparation method thereof. Background Art

[0002] In the broad scope of engineering structure protection, concrete and metal substrates are frequently exposed to extremely harsh environmental tests, which include continuously infiltrating moisture environments, high humidity conditions, corrosive salt spray attacks, and complex and diverse corrosive media in industrial environments. Of particular concern are water-soluble erosive substances such as chloride ions (Cl - ), and sulfate ions (SO4 2- ), which can quietly penetrate deep into the material and induce the rust expansion reaction of the steel bars inside the concrete. This process will inevitably lead to surface cracking of the structure and a sharp decline in the overall mechanical properties. Traditional polymer waterproof coatings have limitations in waterproof performance and lack of interfacial adhesion, making it difficult to effectively block the penetration and migration of moisture. This shortcoming not only seriously weakens the effectiveness of the waterproof layer as a protective barrier but also greatly reduces the environmental protection ability of engineering materials during their actual service life, posing a severe challenge to the long-term stability and operational safety of the structure. There is an urgent need to seek more efficient and reliable protection solutions.

[0003] Superhydrophobic coating technology provides a new solution for the protection of concrete and metal materials with its unique advantages. By constructing micro-nano rough structures and low surface energy modifications, superhydrophobic coatings can significantly enhance the waterproof and anti-corrosion properties of material surfaces. For concrete materials, superhydrophobic coatings can effectively block capillary water absorption and reduce the erosion of moisture on the steel bars inside the concrete; for metal materials, superhydrophobic coatings can form an effective barrier to prevent corrosive media from directly contacting the metal surface, thereby slowing down or preventing the occurrence of the corrosion process. This technology can not only effectively extend the service life of engineering structures but also significantly reduce the maintenance costs of infrastructure, which is of great significance for improving the durability and safety of field concrete structures and metal structures including bridges and docks.

[0004] However, despite the many advantages of superhydrophobic coating technology, the existing systems still face many challenges, such as high raw material costs, specific construction condition limitations, and weak interfacial bonding force between the coating and the substrate, making it difficult to achieve rapid repair and long-term protection of concrete structure or metal structure substrates. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a room-temperature curable superhydrophobic anti-corrosion coating and a preparation method thereof. Based on the cross-scale micro-nano composite structure design and isocyanate directional grafting technology, the preparation of a room-temperature curable superhydrophobic anti-corrosion coating that is universal for concrete and metal substrates is realized.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The first object of the present invention is to provide a method for preparing a room-temperature curable superhydrophobic anti-corrosion coating, comprising the following steps: Using micron particles and nano particles as raw materials, immersing them in a siloxane amination reagent solution, at room temperature, the siloxane amination reagent performs amination modification on the micron particles and nano particles, and then adding an epoxy resin system, and performing a nucleophilic ring-opening reaction at room temperature to form a composite particle solution with dual reaction sites; Coating the composite particle solution on the surface of the substrate for the first time and curing it at room temperature to construct a base layer with a micro-nano rough structure, and then coating the base layer with an alkyl chain isocyanate solution containing a carbon chain length ≥ C12 for the second time. The isocyanate and the composite particles perform a room-temperature crosslinking reaction to form a modification layer, and the micro-nano rough structure is in-situ cured during the crosslinking reaction to obtain a superhydrophobic anti-corrosion coating.

[0008] Furthermore, the mass ratio of the micron particles to the nano particles is 1:3 - 5, the particle size of the micron particles is 1μm - 10μm, the particle size of the nano particles is 6nm - 100nm, and the micron particles and nano particles are both quartz sand, silicon dioxide, boron carbide, basalt, magnetite, alumina, polyamide or polymethyl methacrylate.

[0009] Furthermore, the siloxane amination solution is formed by mixing a siloxane amination reagent, a catalyst and a solvent in a volume ratio of 0.5mL - 1mL:1mL:100mL. The siloxane amination reagent is at least one of N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-methylaminopropyl dimethoxysilane, 3-aminopropyl dimethoxymethylsilane, N-(β-aminoethyl-γ-aminopropyl)methyl dimethoxysilane, the catalyst is ammonia water with a mass concentration of 25% - 28%, and the solvent is at least one of ethanol, ethyl acetate, butyl acetate, ethylene glycol dimethyl ether, acetone.

[0010] Furthermore, the mass ratio of the total mass of the micron particles and nano particles to the epoxy resin system is 5 - 10:1, and the epoxy resin system solution is formed by mixing epoxy resin and a curing agent containing amino groups in a mass ratio of 2 - 4:1.

[0011] Furthermore, the time for amination modification is 0.5h - 2h, and the time for nucleophilic ring-opening reaction is 0.5h - 2h.

[0012] Furthermore, both the first coating and the second coating are carried out by brushing or spraying, the spraying pressure is 0.3MPa - 0.5MPa, and the substrate is concrete or a metal substrate.

[0013] Further, the thickness of the base layer is 1 μm to 100 μm.

[0014] Further, the coating amount of isocyanate in the alkyl chain isocyanate solution with a carbon chain length ≥ C12 is 0.01 g / cm² to 0.02 g / cm², and the alkyl chain isocyanate with a carbon chain length ≥ C12 is at least one of octadecyl isocyanate, dodecyl isocyanate, toluene diisocyanate, and 4-octylphenyl isocyanate.

[0015] Further, the room temperature curing time is 24 h to 72 h, and the room temperature cross-linking reaction time is 72 h to 144 h.

[0016] The second object of the present invention is to provide a room temperature curable superhydrophobic anti-corrosion coating prepared by the above preparation method.

[0017] The present invention has the following beneficial effects compared with the prior art: The preparation method of the room temperature curable superhydrophobic anti-corrosion coating provided by the present invention is based on a universal protection system of micron-nano multi-level composite reinforcement and isocyanate directed grafting. First, based on the cross-scale micro-nano composite structure design, the micro-nano particles are gradient modified, and micron particles and nano particles are compounded to construct a multi-level rough surface. The micron particles and nano particles surface amino-modified with a siloxane amino reagent solution are then used. Subsequently, through the nucleophilic ring-opening reaction of the epoxy group of the epoxy resin with the amino group, composite particles with double reaction sites are formed, sprayed onto the substrate surface, and cured at room temperature. The macroscopic hardness of the coating is improved through the mechanical interlocking effect, and a secondary rough structure is formed along the surface of the micro-nano particles, increasing the air cushion layer and reducing the contact between the water-soluble medium liquid and the substrate. Secondly, based on the isocyanate directed grafting technology, by means of a room temperature self-assembly process, the -NCO group of the long-chain isocyanate (carbon chain length ≥ C12) undergoes a directed cross-linking reaction with the hydroxyl group and amino group in the epoxy resin to form an isocyanurate covalent network containing a long-chain alkyl chain (carbon chain length ≥ C12) on the coating surface, and the in-situ curing of the micro-nano rough structure is realized, reducing the surface energy to endow the substrate material with superhydrophobic properties.

[0018] The preparation method of the room temperature curable superhydrophobic anti-corrosion coating provided by the present invention innovatively adopts a "pre-crosslinking-gradient deposition" process. The composite particle solution is first sprayed onto the substrate surface by two coating methods and cured at room temperature to form a primary protective layer, namely the base layer. Then, an isocyanate solution is coated on the base layer to functionalize the surface layer of the base layer and construct a low surface energy modification layer. Through the two coating processes of the base layer and the modification layer, a gradient deposition process technology is formed to realize the gradient arrangement of the micro-nano particles, and combined with the synergistic effect of the room temperature curing modification process, a resin functional layer with a micro-nano composite structure is constructed on the surface of the concrete and metal substrates to realize the precise construction of the superhydrophobic anti-corrosion coating under the condition of no external heat source.

[0019] The room-temperature-curing superhydrophobic anti-corrosion coating provided by the present invention has a superhydrophobic coating with a contact angle of the substrate > 160° and a rolling angle < 5°, breaking through the dependence on high-temperature curing (> 80°C) in traditional processes. In a salt spray corrosion environment (ASTM B117 standard), this coating can increase the corrosion resistance of metal substrates by 5 to 8 times and extend the service life of the materials by more than 30%. After 500 hours of exposure to 5% NaCl salt spray, the electrochemical impedance of the metal substrate (Q235) still reaches 2.2×10 8 Ω·cm² (a 4-order-of-magnitude increase compared to traditional systems); especially through the room-temperature-curing process, the adhesion remains stable above 14.2 MPa after 1500 hours of accelerated aging test on concrete substrates. Description of the Drawings

[0020] Figure 1 It is the microscopic structure diagram of the superhydrophobic anti-corrosion coating prepared in Example 1 of the present invention.

[0021] Figure 2 It is the microscopic structure diagram of the superhydrophobic anti-corrosion coating prepared in Example 2 of the present invention.

[0022] Figure 3 It is the water droplet contact angle diagram of Example 3 of the present invention.

[0023] Figure 4 It is the water droplet contact angle diagram of Example 4 of the present invention.

[0024] Figure 5 It is the Mapping diagram of the superhydrophobic anti-corrosion coating prepared in Example 5 of the present invention.

[0025] Figure 6 It is the water droplet contact angle diagram of Comparative Example 1 of the present invention.

[0026] Figure 7 It is the water droplet contact angle diagram of Comparative Example 2 of the present invention.

[0027] Figure 8 It is the water droplet contact angle diagram of Comparative Example 3 of the present invention. Detailed Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. In the present invention, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. The present invention does not distinguish components by the difference in nouns, but by the difference in the functions of components. As mentioned throughout the specification and claims, "including" is an open-ended term and should be understood as "including but not limited to".

[0030] It should be noted that the superhydrophobic coating technology provides a new solution for the protection of concrete and metal materials with its unique advantages. By constructing micro-nano rough structures and low surface energy modification, the superhydrophobic coating can significantly enhance the waterproof and anti-corrosion properties of the material surface. Constructing micro-nano structures and incorporating low surface energy substances on the concrete and metal surfaces is an efficient strategy. However, most of the current mainstream preparation technologies rely on siloxane coupling agents and often involve high-temperature treatment (such as >80 °C), which undoubtedly limits the application potential of the superhydrophobic technology in more fields.

[0031] Based on the above problems, the purpose of the present invention is to design a preparation process for a room-temperature curable superhydrophobic anti-corrosion coating that is both easy to operate and has wide applicability, aiming to produce concrete or metal materials with excellent superhydrophobic properties through this process, thereby significantly improving the corrosion resistance of the substrate.

[0032] On the one hand, the present invention provides a method for preparing a room-temperature curable superhydrophobic anti-corrosion coating, including the following steps: S1. Using micron particles and nano particles as raw materials, immersing them in a siloxane amination reagent solution, the siloxane amination reagent performs amination modification on the micron particles and nano particles at room temperature, and then adding an epoxy resin system, and performing a nucleophilic ring-opening reaction at room temperature to form a composite particle solution with dual reaction sites.

[0033] S2. Coating the composite particle solution on the substrate surface for the first time and curing it at room temperature to construct a base layer with a micro-nano rough structure, and then coating the base layer with an alkyl chain isocyanate solution with a carbon chain length ≥ C12 for the second time. The isocyanate and the composite particles perform a room-temperature cross-linking reaction to form a modification layer, and the micro-nano rough structure is in-situ cured during the cross-linking reaction to obtain a superhydrophobic anti-corrosion coating.

[0034] It should be noted that the preparation method of the superhydrophobic anti-corrosion coating provided by the present invention is based on a universal protection system of micron-nano multi-level composite reinforcement and isocyanate directional grafting. First, based on the cross-scale micro-nano composite structure design, the micro-nano particles are gradient modified. Micron particles and nano particles are compounded to construct a multi-level rough surface. The micron particles and nano particles are surface aminated with a siloxane amination reagent solution. Subsequently, through the nucleophilic ring-opening reaction between the epoxy groups and amino groups in the epoxy resin system, composite particles with dual reaction sites are formed, which are sprayed onto the substrate surface and cured at room temperature. The macroscopic hardness of the coating is improved through the mechanical interlocking effect, and a secondary rough structure is formed along the surface of the micro-nano particles, increasing the air cushion layer and reducing the contact between the water-soluble medium liquid and the substrate. Secondly, based on the isocyanate directional grafting technology, by means of a room-temperature self-assembly process, the -NCO groups of the long-chain isocyanate (carbon chain length ≥ C12) undergo a directional cross-linking reaction with the hydroxyl and amino groups in the epoxy resin, forming an isocyanurate covalent network containing long-chain alkyl chains (carbon chain length ≥ C12) on the coating surface, and realizing the in-situ curing of the micro-nano rough structure, reducing the surface energy to endow the substrate material with superhydrophobic properties; however, when the carbon chain length is less than C12, the superhydrophobic properties of the substrate material will deteriorate.

[0035] It should be noted that the present invention innovatively adopts the "pre-crosslinking-gradient deposition" process. The composite particle solution is sprayed onto the substrate surface and cured at room temperature to construct a micro-nano rough structure base layer. The epoxy-based slurry containing micro-nano particles forms a primary protective layer. Then, an isocyanate solution is coated on the constructed micro-nano structure base layer to functionalize the surface layer of the base layer and construct a low surface energy modification layer, realizing the precise construction of the superhydrophobic anti-corrosion coating under the condition of no external heat source.

[0036] In some embodiments, the mass ratio of the micron particles to the nano particles is 1:3 - 5, the particle size of the micron particles is 1 μm - 10 μm, the particle size of the nano particles is 6 nm - 100 nm, and the micron particles and the nano particles are both quartz sand, silicon dioxide, boron carbide, basalt, iron tetroxide, alumina, polyamide or polymethyl methacrylate.

[0037] It should be noted that the micron particles and nano particles of the present invention construct a multi-level rough surface with a specific mass-volume ratio to achieve a multi-scale synergistic effect. At the same time, the low surface energy characteristics of the long-chain isocyanate and the micro-nano structure produce a superhydrophobic synergistic effect, making the static contact angle of the coating > 160° and the rolling angle < 5°.

[0038] It should be noted that the types of micron particles and nano particles provided by the present invention are for the purpose of illustrating the effects of the preparation method of the superhydrophobic anti-corrosion coating of the present invention. The micron particles and nano particles include but are not limited to quartz sand, silicon dioxide, boron carbide, basalt, iron tetroxide, alumina, polyamide or polymethyl methacrylate, which are only for illustrating the technical feasibility rather than limiting the implementation mode.

[0039] In some embodiments, the siloxane amination solution is formed by mixing a siloxane amination reagent, a catalyst and a solvent in a volume ratio of 0.5 mL to 1 mL: 1 mL: 100 mL. The siloxane amination reagent is at least one of N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-methylaminopropyl dimethoxysilane, 3-aminopropyl dimethoxymethylsilane, N-(β-aminoethyl-γ-aminopropyl)methyl dimethoxysilane, etc. The catalyst is ammonia water with a mass concentration of 25% to 28%, and the solvent is at least one of ethanol, ethyl acetate, butyl acetate, ethyl ether glycol, acetone, etc.

[0040] In some embodiments, the mass ratio of the total mass of the micron particles and nano particles to the mass of the epoxy resin system is 5 to 10: 1, and the epoxy resin system is formed by mixing epoxy resin and a curing agent containing amino groups in a mass ratio of 2 to 4: 1.

[0041] It should be noted that for the siloxane amination solution provided by the present invention, under the catalytic condition of ammonia water, the siloxane amination reagent is preferentially hydrolyzed and undergoes a condensation reaction with the surface of the micro / nano particles to carry out surface amination modification on the micro / nano particles. Subsequently, through the nucleophilic ring-opening reaction of the epoxy group of the epoxy resin with the amino group, the micron particles and the nano-phase are gradiently compounded to construct a three-dimensional interlocking network, and the macroscopic hardness of the coating is improved through the mechanical interlocking effect, forming a secondary rough structure along the surface of the micro-nano particles, increasing the air cushion layer, and reducing the contact between the water-soluble medium liquid and the substrate.

[0042] It should be noted that for the epoxy resin system adopted by the present invention, the epoxy resin is preferably bisphenol A type epoxy resin, and the curing agent is a curing agent containing amino groups. The present invention does not make specific limitations on the amino curing agent. The purpose is to cure by the room temperature reaction of bisphenol A type epoxy resin and the amino curing agent, and introduce amino groups into the epoxy resin system to realize the directional reaction of isocyanate with the residual hydroxyl group (-OH) and amine group (-NH2) of the epoxy resin. As a preferred embodiment of the present invention, the curing agent containing amino groups is diethylenetriamine, ethylenediamine, Mannich base, isophorone diamine, 1,3-cyclohexanediamine or N-aminoethyl piperazine.

[0043] In some embodiments, the time for amination modification is 0.5 h to 2 h, and the time for nucleophilic ring-opening reaction is 0.5 h to 2 h.

[0044] In some embodiments, the first coating or the second coating is both applied by brushing or spraying. The spraying pressure is 0.3 MPa to 0.5 MPa, and the substrate is a concrete or metal substrate.

[0045] It should be noted that before using the substrate, surface pretreatment is required to avoid the influence of floating dust and rust layers on the performance of the coating. In a specific embodiment, the following treatment is carried out on the substrate: mechanically polish with sandpaper of 180 mesh to 600 mesh to remove the floating dust or rust layer.

[0046] In some embodiments, the thickness of the base layer is 1 μm to 100 μm.

[0047] In some embodiments, the coating amount of isocyanate in the alkyl chain isocyanate solution with a carbon chain length ≥ C12 is 0.01 g / cm² to 0.02 g / cm². The alkyl chain isocyanate with a carbon chain length ≥ C12 is at least one of octadecyl isocyanate, dodecyl isocyanate, toluene diisocyanate, and 4-octylphenyl isocyanate.

[0048] It should be noted that the present invention adopts a two-coating method. First, the composite particle solution is sprayed onto the surface of the substrate and cured at room temperature to form a primary protective layer, which is the base layer. Then, the isocyanate solution is coated on the base layer to functionalize the surface layer of the base layer and construct a low surface energy modification layer. Through the two-coating processes of the base layer and the modification layer, a gradient deposition process technology is formed to achieve the gradient arrangement of micro-nano particles, and combined with the synergistic effect of the room temperature curing modification process, a resin functional layer with a micro-nano composite structure is constructed on the surface of the concrete and metal substrates.

[0049] It should be noted that the present invention does not limit the specific methods and combination methods of brushing or spraying. The spraying is high-pressure airless spraying. As long as the thickness of the base layer and the coating amount of the cyanate ester are ensured, the three-dimensional network skeleton is formed by the directional cross-linking reaction of the isocyanate and the epoxy resin to achieve the gradient arrangement of micro-nano particles.

[0050] It should be noted that the purpose of the isocyanate provided by the present invention is to illustrate the superhydrophobic synergistic effect of the low surface energy characteristics of the isocyanate and the micro-nano structure, and improve the superhydrophobic anti-corrosion effect of the coating. The isocyanate includes but is not limited to octadecyl isocyanate, dodecyl isocyanate, toluene diisocyanate, and 4-octylphenyl isocyanate, which is only to illustrate the technical feasibility rather than to limit the implementation mode. In some embodiments, the room temperature curing time is 24 h to 72 h, and the room temperature cross-linking reaction time is 72 h to 144 h.

[0051] It should be noted that the present invention utilizes a room-temperature curing and self-assembly method to precisely construct a coating with a thickness of 1 μm to 120 μm and achieve the directional cross-linking of isocyanate and epoxy resin without an external heat source. The prepared superhydrophobic coating system is all prepared at room temperature, endowing it with extremely high scalability and convenient operability. This remarkable characteristic opens up infinite possibilities for the material in a wide range of practical application scenarios, especially in the fields of waterproofing, anti-fouling, and self-cleaning, laying a solid foundation for its application.

[0052] In summary, the method for preparing a room-temperature curing superhydrophobic anti-corrosion coating provided by the present invention constructs a resin functional layer with a micro-nano composite structure on the surfaces of concrete and metal substrates by innovatively designing the coating system, strengthening interfacial chemical bonding, and developing a room-temperature construction process. It is particularly suitable for the overall protection of cross-material composite structures such as bridges, ports, and oil and gas pipelines. The construction window temperature is extended to -5~45°C, effectively solving multiple problems in the prior art and providing a more efficient, environmentally friendly, and economical solution for the protection of concrete and metal structures.

[0053] On the other hand, the present invention also provides a room-temperature curing superhydrophobic anti-corrosion coating prepared by the above preparation method. It should be noted that for the superhydrophobic anti-corrosion coating provided by the present invention, the contact angle of the superhydrophobic coating on the substrate is >160°, and the rolling angle is <5°, breaking through the dependence on high-temperature curing (>80°C) in the traditional process. In a salt spray corrosion environment (ASTM B117 standard), the corrosion resistance of the metal substrate can be increased by 5 to 8 times, the service life of the material can be increased by more than 30%, and the electrochemical impedance of the metal substrate (Q235) after 500 hours of exposure to 5% NaCl salt spray still reaches 2.2×10 8 Ω·cm² (an increase of 4 orders of magnitude compared to the traditional system); especially through the room-temperature curing process, the adhesion of the concrete substrate remains stable above 14.2 MPa after 1500 hours of accelerated aging test.

[0054] The following is further illustrated by specific examples.

[0055] Example 1 This example provides a method for preparing a room-temperature curing superhydrophobic anti-corrosion coating, including the following steps: S1. Provide a concrete substrate: The size of the concrete substrate is 150 mm * 150 mm * 150 mm. Pretreat the surface of the concrete substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove floating dust.

[0056] S2. Modification of micro / nano particles: 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine, 1 mL of ammonia water, and 100 mL of ethanol were successively added to a beaker and mixed to form a siloxane amino-functionalized reagent solution; 0.5 g of micron-sized quartz sand and 1.5 g of nano-sized silica were successively added to the beaker. The particle size of the micron-sized quartz sand was 10 μm, and the particle size of the nano-sized silica was 6 nm. The amino-functionalization modification reaction was carried out by stirring at room temperature for 2 h; then, a two-component epoxy resin system, which was formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of diethylenetriamine curing agent, was added to the beaker, and the secondary modification was carried out by stirring at room temperature for 0.5 h to obtain an epoxy resin-modified micro / nano particle composite solution.

[0057] S3. Coating construction: Using the brushing process, the epoxy resin-modified micro / nano particle composite solution obtained in S2 was brushed onto the surface of the concrete substrate pretreated in S1, and the coating thickness was controlled to be 1 μm. It was cured at room temperature for 24 h to form a micro-nano structure substrate; 1 g of octadecyl isocyanate was dissolved in 100 mL of ethanol to prepare an octadecyl isocyanate ethanol solution, and then the octadecyl isocyanate ethanol solution was sprayed onto the surface of the substrate using a high-pressure airless spraying device. The spraying pressure was 0.3 MPa, and the coating amount was 0.01 g / cm². It was allowed to stand at room temperature for cross-linking for 144 h to obtain a superhydrophobic anti-corrosion coating for the concrete specimen.

[0058] Example 2 This example provides a preparation method for a room-temperature curing superhydrophobic anti-corrosion coating, which includes the following steps: S1. Provide a Q235 carbon steel substrate: The size of the Q235 carbon steel substrate was 150 mm * 150 mm, and the surface of the Q235 carbon steel substrate was pretreated by mechanically grinding the rust layer with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence.

[0059] S2. Modification of micro / nano particles: 0.5 mL of N-methylaminopropyl dimethoxysilane, 1 mL of ammonia water (the concentration of ammonia water was []) and 100 mL of acetone were successively added to a beaker and mixed to form a siloxane amino-functionalized reagent solution; 1.0 g of micron-sized boron carbide and 3.0 g of nano-sized basalt were successively added to the beaker. The particle size of the micron-sized boron carbide was 1 μm, and the particle size of the nano-sized basalt was 50 nm. The amino-functionalization modification reaction was carried out by stirring at room temperature for 2 h; then, a two-component epoxy resin system, which was formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of ethylenediamine curing agent, was added to the beaker, and the secondary modification was carried out by stirring at room temperature for 1 h to obtain an epoxy resin-modified micro / nano particle composite solution.

[0060] S3. Coating construction: Using the brushing process, apply the epoxy resin-modified micro / nano particle composite solution obtained in S2 to the surface of the Q235 carbon steel substrate pretreated in S1, control the coating thickness to be 100 μm, and cure at room temperature for 72 h to form a micro-nano structure base layer; dissolve 2 g of toluene diisocyanate in 100 mL of ethanol to prepare a toluene diisocyanate acetone solution, and then use a high-pressure airless spraying device to spray the toluene diisocyanate acetone solution onto the surface of the base layer. The spraying pressure is 0.5 MPa, the coating amount is 0.02 g / cm², and let it stand for 72 h for room temperature crosslinking to obtain a superhydrophobic anti-corrosion coating for the Q235 carbon steel specimen.

[0061] Example 3 This example provides a preparation method for a room-temperature-curing superhydrophobic anti-corrosion coating, including the following steps: S1. Provide a concrete substrate: The size of the concrete substrate is 150 mm * 150 mm * 150 mm. Pretreat the surface of the concrete substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove floating ash.

[0062] S2. Micro / nano particle modification: Add 1.0 mL of 3-aminopropyldimethoxymethylsilane, 1 mL of ammonia water, and 100 mL of ethanol into a beaker and mix them to form a siloxane amination reagent solution; add 0.5 g of micron-sized iron oxide and 1.5 g of nano-sized polyamide into the beaker in sequence. The particle size of the micron-sized iron oxide is 5 μm, and the particle size of the nano-sized polyamide is 80 nm. Stir at room temperature for 2 h for amination modification reaction; then add a two-component epoxy resin system into the beaker. The two-component epoxy resin system is formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of Mannich base curing agent, and stir at room temperature for 1 h for secondary modification to obtain an epoxy resin-modified micro / nano particle composite solution.

[0063] S3. Coating construction: Using the brushing process, apply the epoxy resin-modified micro / nano particle composite solution obtained in S2 to the surface of the concrete substrate pretreated in S1, control the coating thickness to be 10 μm, and cure at room temperature for 48 h to form a micro-nano structure base layer; dissolve 1 g of dodecyl isocyanate in 100 mL of ethanol to prepare a dodecyl isocyanate ethanol solution, and then use a high-pressure airless spraying device to spray the dodecyl isocyanate ethanol solution onto the surface of the base layer. The spraying pressure is 0.4 MPa, the coating amount is 0.02 g / cm², and let it stand for 96 h for room temperature crosslinking to obtain a superhydrophobic anti-corrosion coating for the concrete specimen.

[0064] Example 4 This example provides a preparation method for a room-temperature-curing superhydrophobic anti-corrosion coating, including the following steps: S1. Provide a Q235 carbon steel substrate: The size of the Q235 carbon steel substrate is 150 mm * 150 mm. Pretreat the surface of the Q235 carbon steel substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove the rust layer.

[0065] S2. Micro / nano particle modification: Add 1.0 mL of N-(β-aminoethyl-γ-aminopropyl) methyl dimethoxysilane, 1 mL of ammonia water, and 100 mL of ethyl acetate into a beaker and mix them to form a siloxane amino-functionalized reagent solution; add 0.5 g of micron alumina and 1.5 g of nano polymethyl methacrylate into the beaker in sequence. The particle size of the micron alumina is 1 μm, and the particle size of the nano polymethyl methacrylate is 60 nm. Stir at room temperature for 2 h for amino-functionalized modification reaction; then add a two-component epoxy resin system into the beaker. The two-component epoxy resin system is formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of isophorone diamine curing agent. Stir at room temperature for 1 h for secondary modification to obtain an epoxy resin-modified micro / nano particle composite solution.

[0066] S3. Coating construction: Use a high-pressure airless spraying device to spray the epoxy resin-modified micro / nano particle composite solution obtained in S2 onto the surface of the Q235 carbon steel substrate pretreated in S1. The spraying pressure is 0.3 MPa, and the coating thickness is controlled to be 10 μm. Cure at room temperature for 48 h to form a micro-nano structure base layer; dissolve 1 g of 4-octylphenyl isocyanate in 100 mL of ethyl acetate to prepare a 4-octylphenyl isocyanate ethyl acetate solution. Then use a high-pressure airless spraying device to spray the 4-octylphenyl isocyanate ethyl acetate solution onto the surface of the base layer. The spraying pressure is 0.3 MPa, and the coating amount is 0.02 g / cm². Let it stand for 96 h for room temperature crosslinking to obtain a superhydrophobic anti-corrosion coating for the Q235 carbon steel specimen.

[0067] Example 5 This example provides a preparation method of a room-temperature curing superhydrophobic anti-corrosion coating, including the following steps: S1. Provide a concrete substrate: The size of the concrete substrate is 150 mm * 150 mm * 150 mm. Pretreat the surface of the concrete substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove the floating dust.

[0068] S2. Modification with micro / nano particles: 1.0 mL of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, 1 mL of ammonia water, and 100 mL of ethylene glycol monoethyl ether were successively added to a beaker and mixed to form a siloxane amination reagent solution; 0.5 g of micron-sized iron oxide (Fe₃O₄) and 1.5 g of nano-sized polymethyl methacrylate were successively added to the beaker. The particle size of the micron-sized iron oxide (Fe₃O₄) was 5 μm, and the particle size of the nano-sized polymethyl methacrylate was 100 nm. The amination modification reaction was carried out by stirring at room temperature for 2 h; then, a two-component epoxy resin system, which was formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of 1,3-cyclohexanedimethanamine curing agent, was added to the beaker, and the secondary modification was carried out by stirring at room temperature for 1 h to obtain a composite solution of epoxy resin-modified micro / nano particles.

[0069] S3. Coating construction: The composite solution of epoxy resin-modified micro / nano particles obtained in S2 was sprayed onto the surface of the concrete substrate pretreated in S1 by using a high-pressure airless spraying device. The spraying pressure was 0.4 MPa, and the coating thickness was controlled to be 10 μm. It was cured at room temperature for 48 h to form a micro-nano structure substrate; 1 g of 4-octylphenyl isocyanate was dissolved in 100 mL of ethylene glycol monoethyl ether to prepare a 4-octylphenyl isocyanate ethyl acetate solution, and then the 4-octylphenyl isocyanate ethyl acetate solution was sprayed onto the surface of the substrate by using a high-pressure airless spraying device. The spraying pressure was 0.4 MPa, and the coating amount was 0.02 g / cm². It was left standing for 96 h for cross-linking at room temperature to obtain a superhydrophobic anti-corrosion coating for the concrete specimen.

[0070] Comparative Example 1 This comparative example provides a preparation method of a room-temperature curing epoxy resin coating, including the following steps: S1. Provide a Q235 carbon steel substrate: The size of the Q235 carbon steel substrate was 150 mm * 150 mm. The surface of the Q235 carbon steel substrate was pretreated, and the rust layer was mechanically removed by using 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence.

[0071] S2. Add a two-component epoxy resin, 0.15 g of bisphenol A epoxy resin, 0.05 g of N-aminoethylpiperazine curing agent, and 100 mL of ethanol to a beaker, mix evenly, and stir for 1 h to obtain an epoxy resin solution.

[0072] S3. Coating construction: The epoxy resin solution obtained in S2 was sprayed onto the surface of the Q235 carbon steel substrate pretreated in S1. The coating thickness was controlled to be 100 μm, and it was cured at room temperature for 144 h to complete cross-linking, obtaining a superhydrophobic anti-corrosion coating for the Q235 carbon steel specimen.

[0073] Comparative Example 2 This comparative example provides a preparation method of a room-temperature curing epoxy micro-nano particle anti-corrosion coating, including the following steps: S1. Provide a Q235 carbon steel substrate: The size of the Q235 carbon steel substrate is 150 mm * 150 mm. Pretreat the surface of the Q235 carbon steel substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove the rust layer.

[0074] S2. Micro / nano particle modification: Add 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine, 1 mL of ammonia water, and 100 mL of ethanol into a beaker in sequence and mix them to form a siloxane amination reagent solution; add 0.5 g of micron-sized quartz sand and 1.5 g of nano-sized silica into the beaker in sequence. The particle size of the micron-sized quartz sand is 10 μm, and the particle size of the nano-sized silica is 6 nm. Stir at room temperature for 2 h for amination modification reaction; then add a two-component epoxy resin system into the beaker. The two-component epoxy resin system is formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of diethylenetriamine curing agent, and stir at room temperature for 0.5 h for secondary modification to obtain an epoxy resin-modified micro / nano particle composite solution.

[0075] S3. Coating construction: Adopt the brushing process, brush the epoxy resin-modified micro / nano particle composite solution obtained in S2 onto the surface of the concrete substrate pretreated in S1, control the coating thickness to be 10 μm, and carry out crosslinking curing at room temperature for 168 h to obtain an epoxy micro / nano particle anti-corrosion coating for the Q235 carbon steel specimen.

[0076] Comparative Example 3 This comparative example provides a preparation method of a room-temperature curing epoxy micro / nano particle anti-corrosion coating, including the following steps: S1. Provide a Q235 carbon steel substrate: The size of the Q235 carbon steel substrate is 150 mm * 150 mm. Pretreat the surface of the Q235 carbon steel substrate, and mechanically polish it with 180-mesh, 320-mesh, and 600-mesh sandpapers in sequence to remove the rust layer.

[0077] S2. Add a two-component epoxy resin system into a beaker. The two-component epoxy resin system is formed by mixing 0.15 g of bisphenol A epoxy resin and 0.05 g of isophorone diamine curing agent, and stir at room temperature for 0.5 h to obtain an epoxy resin composite solution.

[0078] S3. Coating construction: Using the brushing process, apply the epoxy resin composite solution obtained in S2 to the surface of the concrete substrate pretreated in S1, control the coating thickness to be 10 μm, and cure at room temperature for 24 h; dissolve 1 g of octadecyl isocyanate in 100 mL of ethanol to prepare an octadecyl isocyanate ethanol solution, and then use a high-pressure airless spraying device to spray the octadecyl isocyanate ethanol solution onto the surface of the substrate. The spraying pressure is 0.3 MPa, the coating amount is 0.01 g / cm², and let it stand for 144 h for room temperature crosslinking to obtain a hydrophobic anti-corrosion coating for the Q235 carbon steel specimen.

[0079] The structures and properties of the coatings prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested, and the results are as follows: SEM result analysis of the superhydrophobic surfaces prepared in Example 1 and Example 2 shows that Figure 1 This is the microstructural diagram of the superhydrophobic anti-corrosion coating prepared in Example 1 of the present invention. Figure 2 This is the microstructural diagram of the superhydrophobic anti-corrosion coating prepared in Example 2 of the present invention. As Figure 1 and Figure 2 shown, the micro-nano particle structures necessary for forming the superhydrophobic structure can be clearly observed.

[0080] In addition, Figure 5 This is the Mapping diagram of the superhydrophobic anti-corrosion coating prepared in Example 5 of the present invention. As Figure 5 shown, it shows the Mapping diagram of the superhydrophobic anti-corrosion coating in Example 5, where nitrogen elements are evenly distributed on the surface of the coating, indicating that the chemical properties of each part of the coating are highly consistent. These characterization results strongly confirm that the coating strategy designed in the present invention can effectively construct the micro-nano structures required for the superhydrophobic coating on concrete and metal substrates and successfully introduce low-surface-energy substances.

[0081] The water droplet contact angle tests were carried out on the coatings prepared in Examples 1 to 5 and Comparative Examples 1 to 3, and the results are shown in Table 1 and Figures 3 - 4 and Figures 6 - 8 shown.

[0082] Table 1 Water droplet contact angles of the coatings prepared in Examples 1 to 5 and Comparative Example 1 As shown in Table 1 and Figures 3 - 4 and Figures 6 - 8As shown, through the synergistic effect of the room-temperature curing modification process and the coating process, the present invention utilizes the directional cross-linking reaction of isocyanate and epoxy resin to form a three-dimensional network skeleton, and realizes the gradient arrangement of micro-nano particles through the brushing / spraying process. The superhydrophobic coating obtained thereby enables the contact angle of the substrate to be >160° and the rolling angle to be <5°, breaking through the dependence of traditional processes on high-temperature curing (>80°C). According to Table 1 and Figure 6 , Figure 7 and Figure 8 As shown, the water droplet contact angle of ordinary epoxy resin is about 76°. After adding micro-nano particles, the water droplet contact angle of the coating is significantly reduced to 38°. The reason is that the micro-nano particles improve the surface roughness and increase the contact area between the water droplet and the reagents on the surface of the hydrophilic epoxy coating, thereby reducing the water droplet contact angle. On the contrary, after brushing hydrophobic isocyanate molecules on the epoxy surface, the water droplet contact angle increases to 91°, which is due to the effective reduction of the surface energy of the coating by the hydrophobic molecules.

[0083] The coatings prepared in Examples 1 to 5 and Comparative Example 1 were subjected to electrochemical impedance testing, salt spray aging stability, and room-temperature aging tests.

[0084] Among them, electrochemical impedance testing: Through the electrochemical impedance spectroscopy (EIS) test in 3.5% NaCl solution and 500-hour salt spray accelerated test, the long-term anti-corrosion performance of the superhydrophobic coating was systematically evaluated. The results are shown in Table 2. As shown in Table 2, for the EIS performance comparison, the low-frequency impedance modulus (|Z|0.01Hz) of Comparative Example 1 (epoxy coating) is only 10 7 orders of magnitude, indicating its weak anti-permeation barrier ability; the impedance moduli shown by Examples 2 and 4 (superhydrophobic coatings) are as high as 10 12 orders of magnitude, which is 5 orders of magnitude higher than that of Comparative Example 1.

[0085] Salt spray aging stability: As shown in Table 2, after 500 hours of salt spray exposure, the water droplet contact angles of Examples 2 and 4 are still >130°, and maintain an impedance modulus of 10 8 orders of magnitude, still maintaining a high level of protection performance; the water droplet contact angle of Comparative Example 1 has become <40°, and the impedance modulus has sharply decreased to 10 4 orders of magnitude, and the protection performance is almost lost. This is mainly attributed to the protective effect of the "air cushion layer" stored in the micro-nano structure on the surface of the superhydrophobic coating.

[0086] Room-temperature aging test: As shown in Table 2, after 1500 hours of accelerated aging at room temperature, the adhesion of Examples 2 and 4 is still greater than 14 MPa, while that of Comparative Example 1 has decreased to 8.7 MPa. This is mainly attributed to the shielding effect of the micro / nano particles in the superhydrophobic coating on ultraviolet rays, thereby delaying the plasticization failure of the bonding interface.

[0087] Table 2 Test Results of Electrochemical Impedance, Salt Spray Aging Stability and Room Temperature Aging Test In summary, based on the design of cross-scale micro-nano composite structures, this invention modifies micro-nano particles in a gradient manner, constructs a multi-level rough surface by compounding micron particles and nano particles, uses micron particles and nano particles surface-aminated with a siloxane amination reagent solution, and then forms composite particles with dual reaction sites through the nucleophilic ring-opening reaction between the epoxy groups of epoxy resin and amino groups. The composite particles are sprayed onto the substrate surface and cured at room temperature. The macroscopic hardness of the coating is improved through the mechanical interlocking effect, and a secondary rough structure is formed along the surface of the micro-nano particles, increasing the air cushion layer and reducing the contact between the water-soluble medium liquid and the substrate. Based on the isocyanate directional grafting technology, by means of a room-temperature self-assembly process, the -NCO groups of long-chain isocyanates (carbon chain length ≥ C12) undergo a directional cross-linking reaction with the hydroxyl and amino groups in the epoxy resin to form an isocyanurate covalent network containing long-chain alkyl chains (carbon chain length ≥ C12) on the coating surface, and in-situ curing of the micro-nano rough structure is achieved, reducing the surface energy to endow the substrate material with superhydrophobic properties. The "pre-crosslinking - gradient deposition" process is innovatively adopted. The composite particle solution is sprayed onto the substrate surface and cured at room temperature to construct a micro-nano rough structure base layer, and an epoxy-based slurry containing micro-nano particles forms a primary protective layer. Then, an isocyanate solution is coated on the constructed micro-nano structure base layer to functionalize the surface layer of the base layer and construct a low surface energy modification layer, realizing the precise construction of a superhydrophobic anti-corrosion coating under the condition of no external heat source.

[0088] Analysis of the mechanism of action: The superhydrophobic coating prepared by this invention realizes a triple protection effect through the micro-nano composite structure: ① Physical barrier effect: The micron-level and nano-level structures on the surface form a multi-level rough interface; ② Gas film isolation effect: The air layer stored at the interface (contact angle > 165°) blocks the diffusion path of corrosion media such as Cl-; ③ Chemical passivation effect: The long-chain isocyanate cross-linking network inhibits the anodic dissolution reaction of electrochemical corrosion. Therefore, this invention significantly improves the protection life of materials in harsh corrosion environments, providing an innovative solution for corrosion prevention and control in fields such as temporary water environments, marine engineering equipment, and coastal infrastructure.

[0089] It should be noted that when this invention involves numerical ranges, it should be understood that any value between the two endpoints of each numerical range and either of the two endpoints can be selected. Since the adopted step methods are the same as those in the embodiments, in order to prevent repetition, this invention describes the preferred embodiments. Although the preferred embodiments of this invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0090] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of a room-temperature curable superhydrophobic anti-corrosion coating, characterized in that, It includes the following steps: Using micron particles and nano particles as raw materials, immersing them in a siloxane amination reagent solution, at room temperature, the siloxane amination reagent performs amination modification on the micron particles and nano particles, then adding an epoxy resin system, and performing a nucleophilic ring-opening reaction at room temperature to form a composite particle solution with dual reaction sites; Coating the composite particle solution on the surface of the substrate for the first time, curing at room temperature to construct a base layer with a micro-nano rough structure, coating the alkyl chain isocyanate solution with a carbon chain length ≥ C12 on the base layer for the second time, and the isocyanate and the composite particles perform a room temperature cross-linking reaction to form a modified layer. During the cross-linking reaction process, the micro-nano rough structure is in-situ cured to obtain a room temperature cured superhydrophobic anti-corrosion coating.

2. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, characterized in that The mass ratio of the micron particles to the nano particles is 1:3 - 5, the particle size of the micron particles is 1μm - 10μm, the particle size of the nano particles is 6nm - 100nm, and the micron particles and nano particles are both quartz sand, silicon dioxide, boron carbide, basalt, iron tetroxide, alumina, polyamide or polymethyl methacrylate.

3. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, characterized in that, The siloxane amination solution is formed by mixing a siloxane amination reagent, a catalyst and a solvent in a volume ratio of 0.5mL - 1mL:1mL:100mL. The siloxane amination reagent is at least one of N-[3-(trimethoxysilyl)propyl]ethylenediamine, N-methylaminopropyl dimethoxysilane, 3-aminopropyldimethoxymethylsilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, the catalyst is ammonia water with a mass concentration of 25% - 28%, and the solvent is at least one of ethanol, ethyl acetate, butyl acetate, ethylene glycol dimethyl ether, acetone.

4. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, wherein, The mass ratio of the total mass of the micron particles and nano particles to the mass of the epoxy resin system is 5 - 10:1, and the epoxy resin system solution is mixed with an epoxy resin and a curing agent containing amino groups in a mass ratio of 2 - 4:

1.

5. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, characterized in that, The time for amination modification is 0.5h - 2h, and the time for nucleophilic ring-opening reaction is 0.5h - 2h.

6. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, wherein, Both the first coating and the second coating are carried out by brushing or spraying, the spraying pressure is 0.3MPa - 0.5MPa, and the substrate is concrete or a metal substrate.

7. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, wherein The thickness of the base layer is 1μm - 100μm.

8. The preparation method of the room-temperature curing superhydrophobic anti-corrosion coating according to claim 1, wherein The coating amount of the isocyanate in the alkyl chain isocyanate solution with a carbon chain length ≥ C12 is 0.01g / cm² - 0.02g / cm², and the alkyl chain isocyanate with a carbon chain length ≥ C12 is at least one of octadecyl isocyanate, dodecyl isocyanate, toluene diisocyanate, 4-octylphenyl isocyanate.

9. The preparation method of the room-temperature curable superhydrophobic anti-corrosion coating according to claim 1, characterized in that, The time for room temperature curing is 24h - 72h, and the time for room temperature cross-linking reaction is 72h - 144h.

10. A room-temperature curable superhydrophobic anti-corrosion coating, characterized in that, Prepared by using the preparation method described in any one of claims 1 - 9.

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