Anticorrosive flame-retardant coating and preparation method thereof

Abstract

The invention provides an anticorrosive flame-retardant coating and a preparation method thereof, and belongs to the technical field of coating compositions.The preparation method comprises the following steps that S1, a WPU-SS emulsion is prepared; s2, preparing a composite flame-retardant reinforced material; s3, uniformly mixing the WPU-SS emulsion with the water-borne epoxy resin emulsion, sequentially adding glass flakes, ammonium polyphosphate, the composite flame-retardant reinforcing material, titanium dioxide and an auxiliary agent, mixing and stirring, then adding a curing component, and mixing and stirring to obtain the anti-corrosion flame-retardant coating. According to the invention, the flame-retardant performance can be improved, and meanwhile, the anti-corrosion performance is relatively good.

Description

Technical Field

[0001] This invention relates to the field of coating composition technology, specifically to an anti-corrosion and flame-retardant coating and its preparation method. Background Technology

[0002] Corrosion-resistant and flame-retardant coatings are a type of functional coating that combines corrosion protection and combustion inhibition, and can be used to protect the surfaces of metallic, non-metallic, and polymeric materials. In the field of wires and cables, in addition to basic surface protection, coatings must be able to resist the effects of complex environments such as water vapor, oxygen, corrosive media, and alternating hot and cold temperatures, and provide flame-retardant and smoke-suppressing protection under overload heating, short circuits, or external fire sources. Therefore, developing coatings with both excellent corrosion resistance and flame-retardant properties is of great significance for improving the safety and service stability of substrates such as wires and cables.

[0003] In existing technologies, anti-corrosion and flame-retardant coatings typically use epoxy resin, acrylic resin, chlorinated polymer, waterborne polyurethane, or a composite system thereof as the film-forming base material. Among these, epoxy systems have advantages such as strong adhesion, good resistance to media, and dense film formation, and are therefore widely used in anti-corrosion coatings. However, when epoxy resin is used alone, the resulting coating is often hard and brittle, and is prone to microcracks under alternating hot and cold temperatures or mechanical stress. This provides channels for the penetration of water vapor, oxygen, and corrosive media, leading to a decrease in anti-corrosion performance.

[0004] In addition, to improve the flame retardant properties of coatings, existing technologies often introduce halogenated flame retardants into the coating system to enhance the overall flame retardant effect. However, these flame retardants easily release corrosive and irritating gases during combustion, and have high smoke density, making it difficult to meet the development requirements of low smoke, low toxicity, and environmental protection. Intumescent flame retardant systems have attracted attention in anti-corrosion and flame retardant coatings due to their good flame retardant efficiency and low smoke toxicity. Among them, ammonium polyphosphate is often used as an intumescent flame retardant component. However, the char layer formed by using ammonium polyphosphate alone usually suffers from problems such as insufficient continuity, poor density, and limited structural strength. The intumescent char layer formed after heating is prone to loosening, cracking, or local collapse, resulting in limited barrier effects against heat, oxygen, and combustible volatiles, thus affecting the overall flame retardant effect and smoke suppression performance of the coating.

[0005] Therefore, there is a need to provide an anti-corrosion and flame-retardant coating and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0006] In view of this, the present invention provides an anti-corrosion and flame-retardant coating and its preparation method, which can improve flame-retardant performance while having good anti-corrosion performance.

[0007] To achieve the above objectives, the present invention provides a method for preparing an anti-corrosion and flame-retardant coating, comprising the following steps: S1. Cystamine dihydrochloride was dissolved in deionized water and the pH was adjusted. Then, it was added dropwise to WPU predispersant at room temperature. After the addition was complete, the temperature was raised to react, the organic solvent was removed under reduced pressure, and deionized water was added and mixed to obtain WPU-SS emulsion. S2. Disperse carbon balls in deionized water, add dopamine hydrochloride and adenosine triphosphate under continuous stirring, adjust pH, stir reaction, centrifuge, wash, add to deionized water, sonicate, add zinc sulfate heptahydrate and sodium stannate trihydrate in sequence, stir reaction, centrifuge, wash, vacuum dry to obtain composite flame retardant reinforced material. S3. Mix WPU-SS emulsion with water-based epoxy resin emulsion, then add glass flakes, ammonium polyphosphate, composite flame-retardant reinforcing material, titanium dioxide and additives in sequence, mix and stir, then add curing components and mix and stir to obtain anti-corrosion and flame-retardant coating.

[0008] This invention introduces cystamine dihydrochloride into a WPU pre-dispersion system to prepare an aqueous polyurethane emulsion (WPU-SS emulsion) with disulfide bonds in the main chain. This emulsion is then compounded with an aqueous epoxy resin emulsion, which effectively combines the flexibility of the polyurethane system with the density, adhesion, and mechanical strength of the epoxy resin system. The cystamine dihydrochloride molecule contains disulfide bonds, which can introduce dynamic disulfide bond units into the polyurethane (WPU) chain segments. These disulfide bonds can undergo reversible exchange under appropriate temperature and chain segment activity conditions, thus endowing the system with a certain self-healing potential for microcracks. This reduces the risk of corrosive media penetrating the substrate surface along coating defects. Combined with the layered structure of glass flakes, it can also form a tortuous barrier path within the coating, extending the diffusion path of corrosive media. Furthermore, the flexibility of WPU itself and the high adhesion and density of epoxy resin further enhance the anti-corrosion performance of the coating.

[0009] This invention utilizes the surface adhesion of polydopamine to deposit adenosine triphosphate on the surface of carbon spheres, introduces phosphorus- and nitrogen-containing active structures on the surface of the carbon spheres, and further introduces zinc stannate / zinc hydroxystannate inorganic phases in situ to obtain a composite flame-retardant reinforced material. Among them, adenosine triphosphate (ATP) provides phosphorus, nitrogen, and carbon active structures, which is beneficial for promoting the dehydration and char formation of the matrix when heated; polydopamine can serve as an interfacial adhesion transition layer, improving the dispersion and interfacial bonding of the composite flame-retardant reinforcing material in the coating matrix, and can also promote the formation and stability of the char layer with its nitrogen-containing aromatic structure; combined with added ammonium polyphosphate, an intumescent flame-retardant system can be synergistically constructed, making it easier for the final coating to form a continuous, dense, and stable intumescent char layer at high temperatures, thereby effectively isolating heat and oxygen; at the same time, the outer zinc stannate / zinc hydroxystannate inorganic phase can play a synergistic role in Lewis acid catalysis of char formation, inorganic framework support, and smoke suppression, promoting the formation of more char residue and improving the structural strength, density, and thermal stability of the char layer, thereby reducing heat release, smoke generation, and toxic gas release during combustion, and thus playing a flame-retardant and smoke-suppressing effect in the overall system.

[0010] Optionally, the WPU predispersant is obtained by vacuum dehydrating polytetrahydrofuran ether diol at 100-110°C and -0.08 MPa for 2-3 hours, then cooling to 60-65°C and purging with nitrogen, adding isophorone diisocyanate and dibutyltin dilaurate, and reacting at 80°C for 2-3 hours; then cooling the system to 70°C, adding dimethylolpropionic acid and acetone, and continuing the reaction for 60-80 minutes, then cooling to 30-35°C, adding triethylamine for neutralization for 25-35 minutes; and then adding deionized water in batches at 2000 r / min for phase inversion emulsification for 20-30 minutes.

[0011] Optionally, the WPU predispersant comprises the following raw materials in parts by weight: 38-42 parts polytetrahydrofuran ether diol, 11-13 parts isophorone diisocyanate, 0.05-0.12 parts dibutyltin dilaurate, 2.8-3.6 parts dimethylolpropionic acid, 6-10 parts acetone, 2.1-2.7 parts triethylamine, and 50-60 parts deionized water.

[0012] Optionally, in step S1, cystamine dihydrochloride is dissolved in deionized water, and the pH is adjusted to 7.5-8.0 with a 1 mol / L NaOH solution. Then, it is added dropwise to the WPU pre-dispersion at room temperature. After the addition is complete, the temperature is raised to 60°C and reacted for 2-3 hours. The organic solvent is removed under reduced pressure, and deionized water is added and mixed to obtain the WPU-SS emulsion.

[0013] In this invention, cystamine dihydrochloride is dissolved in deionized water and the pH is adjusted to 7.5-8.0, which is beneficial for neutralizing its hydrochloride form and releasing free amino groups with high reactivity, thereby promoting the chain extension reaction with isocyanate groups in WPU pre-dispersion and improving the disulfide bond structure introduction efficiency. Furthermore, after the chain extension reaction is completed, the organic solvent is removed under reduced pressure to reduce the adverse effects of residual solvent on the subsequent film uniformity and coating density.

[0014] Optionally, the carbon spheres are obtained by ultrasonically dispersing 15-20 parts by weight of glucose in 80-150 parts by weight of deionized water for 20-30 minutes, transferring the mixture to a hydrothermal reactor, reacting it at 170-180℃ for 20-24 hours, and then washing it repeatedly with ethanol and deionized water 2-3 times.

[0015] This invention synthesizes carbon spheres via hydrothermal synthesis of glucose. The raw materials are inexpensive and readily available, the preparation process is mild and controllable, and the resulting carbon spheres have good dispersibility and contain certain oxygen-containing functional groups on their surface, which is beneficial for subsequent surface modification and flame retardant component loading.

[0016] Optionally, in step S2, carbon spheres are dispersed in deionized water, and dopamine hydrochloride and adenosine triphosphate are added under continuous stirring. The pH of the system is adjusted to 8.2-8.6 with a 0.1 mol / L Tris-HCl buffer solution. The reaction is continued at room temperature for 15-18 hours. After centrifugation and washing, the mixture is added to deionized water and sonicated for 20-30 minutes. Zinc sulfate heptahydrate and sodium stannate trihydrate are added sequentially. The reaction is continued at room temperature for 6-8 hours, followed by centrifugation and washing. The mixture is then vacuum dried at 60-65°C for 10-12 hours to obtain the composite flame-retardant reinforced material.

[0017] Optionally, the curing component is prepared by pre-crushing 2-2.5 parts by weight of 4,4'-diaminodiphenyl disulfide into micro powder, and mixing it with 0.8-1 parts by weight of propylene carbonate and 0.1-0.2 parts by weight of dispersant for 5-10 minutes.

[0018] The 4,4'-diaminodiphenyl disulfide molecule described in this invention contains active amino groups and disulfide bonds. The active amino groups can undergo ring-opening reactions with the epoxy groups in the aqueous epoxy resin emulsion, participating in cross-linking and curing to form a three-dimensional cross-linked network. The disulfide bonds in the molecule can be introduced into the curing network as dynamic covalent bonds, which is beneficial for regulating the cross-linked network structure, improving the coating flexibility to a certain extent, and alleviating the coating's tendency to crack. Furthermore, this invention first pulverizes the molecule into micro-powder and then pre-forms it into a slurry with propylene carbonate and a dispersant. Propylene carbonate helps to wet the curing agent particles and improve their dispersion in the composite emulsion system, while the dispersant helps to inhibit particle agglomeration, thereby improving the uniformity of the distribution of the curing components in the system, reducing localized cross-linking unevenness and curing defects, and ultimately contributing to the formation of a more uniform and dense coating.

[0019] Optionally, the additives include 0.5 to 1.0 parts by weight of dispersant, 0.15 to 0.3 parts by weight of wetting agent, and 0.1 to 0.3 parts by weight of defoamer.

[0020] Preferably, the dispersant is DISPERBYK-190, the wetting agent is BYK-348, and the defoamer is BYK-024.

[0021] Optionally, in step S3, the WPU-SS emulsion and the water-based epoxy resin emulsion are mixed evenly, and glass flakes, ammonium polyphosphate, composite flame-retardant reinforcing material, titanium dioxide, and additives are added in sequence. After mixing and stirring at 1200~1600 r / min for 30~40 min, the curing component is added and mixed and stirred at 1600~2000 r / min for 10~15 min to obtain the anti-corrosion and flame-retardant coating.

[0022] The present invention also provides an anti-corrosion and flame-retardant coating, comprising the following raw materials in parts by weight: 28-42 parts WPU-SS emulsion, 12-18 parts waterborne epoxy resin emulsion, 0.8-1.5 parts glass flakes, 5-7 parts ammonium polyphosphate, 1.5-2 parts composite flame-retardant reinforcing material, 1.5-2 parts titanium dioxide, 2.9-3.7 parts curing component, and 0.75-1.6 parts additives; The composite flame-retardant reinforcing material comprises the following raw materials in parts by weight: 1-2 parts carbon spheres, 0.6-1.5 parts dopamine hydrochloride, 1.2-2 parts adenosine triphosphate, 18-23 parts zinc sulfate heptahydrate, and 18-20 parts sodium stannate trihydrate.

[0023] This invention utilizes the above-mentioned component ratio, employing WPU-SS emulsion and waterborne epoxy resin emulsion as composite film-forming base materials. The former imparts good flexibility and a certain potential for damage repair to the coating, while the latter helps improve the crosslinking density, adhesion, and protective stability of the coating. Simultaneously, ammonium polyphosphate and the composite flame-retardant reinforcing material can form a good flame-retardant synergistic effect. Ammonium polyphosphate promotes expansion into char, while the composite flame-retardant reinforcing material promotes catalytic char formation and enhances the strength, density, and thermal stability of the char layer, thereby improving the flame-retardant performance of the coating and reducing smoke and toxic gas release. Furthermore, the glass flakes form a sheet-like shielding structure in the coating, which can extend the penetration path of corrosive media, thus improving the coating's corrosion resistance.

[0024] The above-described technical solution of the present invention has at least the following beneficial effects: 1. This invention prepares an aqueous polyurethane emulsion (WPU-SS emulsion) with disulfide bonds in its main chain by chain extension using cystamine dihydrochloride, and then blends it with an aqueous epoxy resin emulsion, thus balancing the flexibility of polyurethane with the density, adhesion, and mechanical properties of epoxy resin. The dynamic disulfide bonds introduced by cystamine dihydrochloride can undergo reversible exchange under appropriate conditions, endowing the coating with a certain potential for self-healing microcracks; combined with the layered shielding effect of glass flakes, the diffusion path of corrosive media can be extended, thereby improving the anti-corrosion performance of the coating.

[0025] 2. This invention utilizes polydopamine to deposit adenosine triphosphate (ATP) onto the surface of carbon spheres and introduces zinc stannate / zinc hydroxystannate inorganic phases in situ to prepare a composite flame-retardant reinforcing material. ATP provides the active structures of phosphorus, nitrogen, and carbon, while polydopamine promotes dispersion, interfacial bonding, and char stabilization. Combined with ammonium polyphosphate, it can synergistically construct an intumescent flame-retardant system. The outer zinc stannate / zinc hydroxystannate inorganic phase can also catalyze char formation, support the char layer, and exert a smoke-suppressing effect, thereby improving the flame-retardant and smoke-suppressing performance of the coating. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0027] Example 1 38g of polytetrahydrofuran ether diol (molecular weight 2000) was dehydrated under vacuum at 100℃ and -0.08MPa for 2h. The temperature was then lowered to 60℃ and protected with nitrogen. 11g of isophorone diisocyanate and 0.05g of dibutyltin dilaurate were added, and the mixture was heated to 80℃ and reacted for 2h to obtain an isocyanate-terminated prepolymer. The system was then cooled to 70℃, and 2.8g of dimethylolpropionic acid and 6g of acetone were added. The reaction was continued for 60min, then cooled to 30℃, and 2.1g of triethylamine was added for neutralization for 25min. Subsequently, 50g of deionized water was added in batches at 2000r / min for phase inversion emulsification for 20min to obtain WPU predispersant; 2g of cystamine dihydrochloride was dissolved in 7g of deionized water, and the pH was adjusted to 7.5 with 1mol / L NaOH solution. The solution was then added dropwise to the WPU predispersant at room temperature. After the addition was complete, the temperature was raised to 60℃ and reacted for 2h. The organic solvent was removed under reduced pressure, and 8g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0028] 15g of glucose was added to 80g of deionized water and ultrasonically dispersed for 20min. The mixture was then transferred to a hydrothermal reactor and reacted at 170℃ for 20h. Afterward, the mixture was washed twice with ethanol and deionized water to obtain carbon spheres. 1g of carbon spheres was added to 200g of deionized water and dispersed. Under continuous stirring, 0.6g of dopamine hydrochloride and 1.2g of adenosine triphosphate were added, and the pH of the system was adjusted to 8.2 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 15h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 20min. Then, 18g of zinc sulfate heptahydrate and 18g of sodium stannate trihydrate were added sequentially. The mixture was stirred and reacted at room temperature for 6h, centrifuged and washed, and then vacuum dried at 60℃ for 10h to obtain the composite flame-retardant reinforced material.

[0029] 2g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into a fine powder and mixed with 0.8g of propylene carbonate and 0.1g of dispersant (model: DISPERBYK-190) for 5 minutes to prepare the curing component; 28g WPU-SS emulsion was mixed with 12g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model number 0947A-60W). Then, 0.8g of glass flakes (400 mesh), 5g of ammonium polyphosphate, 1.5g of composite flame retardant reinforcing material, 0.5g of dispersant (model number: DISPERBYK-190), 0.15g of wetting agent (model number: BYK-348), 0.1g of defoamer (model number: BYK-024), and 1.5g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model number: R-566) were added sequentially. The mixture was stirred at 1200r / min for 30min. Then, 2.9g of curing component was added and the mixture was stirred at 1600r / min for 10min to obtain the anti-corrosion and flame retardant coating.

[0030] Example 2 42g of polytetrahydrofuran ether diol (molecular weight 2000) was vacuum dehydrated at 110℃ and -0.08MPa for 3h, then cooled to 65℃ and protected with nitrogen. 13g of isophorone diisocyanate and 0.12g of dibutyltin dilaurate were added, and the mixture was heated to 80℃ and reacted for 3h to obtain an isocyanate-terminated prepolymer. The system was then cooled to 70℃, 3.6g of dimethylolpropionic acid and 10g of acetone were added, and the reaction continued for 80min. The mixture was then cooled to 35℃, and 2.7g of triethylamine was added for neutralization for 35min. Then, under conditions of 2000 r / min, 60 g of deionized water was added in batches for phase inversion emulsification for 30 min to obtain WPU pre-dispersion; 2.5 g of cystamine dihydrochloride was dissolved in 10 g of deionized water, and the pH was adjusted to 8.0 with 1 mol / L NaOH solution. The solution was then added dropwise to the WPU pre-dispersion at room temperature. After the addition was completed, the temperature was raised to 60 °C and reacted for 3 h. The organic solvent was removed under reduced pressure, and 12 g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0031] 20g of glucose was added to 150g of deionized water and ultrasonically dispersed for 30min. The mixture was then transferred to a hydrothermal reactor and reacted at 180℃ for 24h. Afterward, the mixture was washed three times with ethanol and deionized water to obtain carbon spheres. 2g of carbon spheres were added to 300g of deionized water and dispersed. Under continuous stirring, 1.5g of dopamine hydrochloride and 2g of adenosine triphosphate were added, and the pH of the system was adjusted to 8.6 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 18h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 30min. Then, 23g of zinc sulfate heptahydrate and 20g of sodium stannate trihydrate were added sequentially. The mixture was stirred and reacted at room temperature for 8h, centrifuged and washed, and then vacuum dried at 65℃ for 12h to obtain the composite flame-retardant reinforced material.

[0032] 2.5g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into a fine powder and mixed with 1g of propylene carbonate and 0.2g of dispersant (model: DISPERBYK-190) for 10 minutes to prepare the cured component; 42g WPU-SS emulsion was mixed with 18g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model number 0947A-60W). Then, 1.5g of glass flakes (400 mesh), 7g of ammonium polyphosphate, 2g of composite flame retardant reinforcing material, 1.0g of dispersant (model number: DISPERBYK-190), 0.3g of wetting agent (model number: BYK-348), 0.3g of defoamer (model number: BYK-024), and 2g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model number: R-566) were added sequentially. The mixture was stirred at 1600r / min for 40min. Then, 3.7g of curing component was added and the mixture was stirred at 2000r / min for 15min to obtain the anti-corrosion and flame retardant coating.

[0033] Example 3 40g of polytetrahydrofuran ether diol (molecular weight 2000) was dehydrated under vacuum at 105℃ and -0.08MPa for 2.5h. Then, the temperature was lowered to 62℃ and nitrogen protection was applied. 12g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate were added, and the temperature was raised to 80℃ and reacted for 2.5h to obtain a prepolymer with terminal isocyanate groups. The system was then lowered to 70℃, 3.2g of dimethylolpropionic acid and 8g of acetone were added, and the reaction was continued for 70min. After that, the temperature was lowered to 32℃, and 2.4g of triethylamine was added for neutralization for 30min. Subsequently, 55g of deionized water was added in batches at 2000r / min for phase inversion emulsification for 25min to obtain WPU predispersant; 2.2g of cystamine dihydrochloride was dissolved in 8g of deionized water, and the pH was adjusted to 7.8 with 1mol / L NaOH solution. The solution was then added dropwise to the WPU predispersant at room temperature. After the addition was complete, the temperature was raised to 60℃ and reacted for 2.5h. The organic solvent was removed under reduced pressure, and 10g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0034] 18g of glucose was added to 120g of deionized water and ultrasonically dispersed for 25min. The mixture was then transferred to a hydrothermal reactor and reacted at 175℃ for 22h. Afterward, the mixture was washed three times with ethanol and deionized water to obtain carbon spheres. 1.5g of carbon spheres were added to 250g of deionized water and dispersed. Under continuous stirring, 1.0g of dopamine hydrochloride and 1.6g of adenosine triphosphate were added, and the pH of the system was adjusted to 8.5 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 16h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 25min. Then, 20g of zinc sulfate heptahydrate and 19g of sodium stannate trihydrate were added sequentially. The mixture was stirred and reacted at room temperature for 7h. After centrifugation and washing, the mixture was vacuum dried at 62℃ for 11h to obtain the composite flame-retardant reinforced material.

[0035] 2.2 g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into a fine powder and mixed with 0.9 g of propylene carbonate and 0.15 g of dispersant (model: DISPERBYK-190) for 8 minutes to prepare the cured component; 35 g WPU-SS emulsion was mixed with 15g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model number 0947A-60W). Then, 1.2g of glass flakes (400 mesh), 6g of ammonium polyphosphate, 1.8g of composite flame-retardant reinforcing material, 0.7g of dispersant (model number: DISPERBYK-190), 0.22g of wetting agent (model number: BYK-348), 0.18g of defoamer (model number: BYK-024), and 1.8g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model number: R-566) were added sequentially. The mixture was stirred at 1400r / min for 35min. Then, 3.25g of curing component was added and the mixture was stirred at 1800r / min for 12min to obtain the anti-corrosion and flame-retardant coating.

[0036] Example 4 39 g of polytetrahydrofuran ether diol (molecular weight 2000) was dehydrated under vacuum at 102 °C and -0.08 MPa for 2.2 h. The mixture was then cooled to 61 °C and protected with nitrogen. 11.5 g of isophorone diisocyanate and 0.06 g of dibutyltin dilaurate were added, and the mixture was heated to 80 °C and reacted for 2.2 h to obtain an isocyanate-terminated prepolymer. The system was then cooled to 70 °C, and 3.0 g of dimethylolpropionic acid and 7 g of acetone were added. The reaction was continued for 65 min, then cooled to 31 °C, and 2.2 g of triethylamine was added for neutralization for 28 min. Subsequently, 52g of deionized water was added in batches at 2000r / min for phase inversion emulsification for 22min to obtain WPU predispersant; 2.1g of cystamine dihydrochloride was dissolved in 7.5g of deionized water, and the pH was adjusted to 7.6 with 1mol / L NaOH solution. The solution was then added dropwise to the WPU predispersant at room temperature. After the addition was complete, the temperature was raised to 60℃ and reacted for 2.2h. The organic solvent was removed under reduced pressure, and 9g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0037] 16g of glucose was added to 100g of deionized water and ultrasonically dispersed for 22min. The mixture was then transferred to a hydrothermal reactor and reacted at 172℃ for 21h. The mixture was then washed twice with ethanol and deionized water to obtain carbon spheres. 1.2g of carbon spheres were added to 220g of deionized water and dispersed. 0.8g of dopamine hydrochloride and 1.4g of adenosine triphosphate were added under continuous stirring. The pH of the system was adjusted to 8.3 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 15.5h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 22min. Then, 19g of zinc sulfate heptahydrate and 18.5g of sodium stannate trihydrate were added. The mixture was stirred and reacted at room temperature for 6.5h. After centrifugation and washing, the mixture was vacuum dried at 61℃ for 10.5h to obtain the composite flame-retardant reinforced material.

[0038] 2.1g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into micro powder and mixed with 0.85g of propylene carbonate and 0.12g of dispersant (model: DISPERBYK-190) for 6 minutes to prepare the curing component; 32g of WPU-SS emulsion was mixed with 13.5g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model: 0947A-60W), and 1.0g of glass flakes (400 mesh), 5.5g of ammonium polyphosphate, and 1. 6g of composite flame-retardant reinforcing material, 0.6g of dispersant (model: DISPERBYK-190), 0.18g of wetting agent (model: BYK-348), 0.15g of defoamer (model: BYK-024), and 1.6g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model: R-566) were mixed and stirred at 1300r / min for 32min. Then, 3.07g of curing component was added and mixed and stirred at 1700r / min for 11min to obtain an anti-corrosion and flame-retardant coating.

[0039] Example 5 41 g of polytetrahydrofuran ether diol (molecular weight 2000) was dehydrated under vacuum at 108 °C and -0.08 MPa for 2.8 h. The mixture was then cooled to 64 °C and protected with nitrogen. 12.5 g of isophorone diisocyanate and 0.10 g of dibutyltin dilaurate were added, and the mixture was heated to 80 °C and reacted for 2.8 h to obtain a prepolymer with terminal isocyanate groups. The system was then cooled to 70 °C, and 3.4 g of dimethylolpropionic acid and 9 g of acetone were added. The reaction was continued for 75 min, then cooled to 34 °C, and 2.6 g of triethylamine was added for neutralization for 33 min. Subsequently, 58g of deionized water was added in batches at 2000r / min for phase inversion emulsification for 28min to obtain WPU pre-dispersion; 2.4g of cystamine dihydrochloride was dissolved in 9g of deionized water, and the pH was adjusted to 7.9 with 1mol / L NaOH solution. The solution was then added dropwise to the WPU pre-dispersion at room temperature. After the addition was complete, the temperature was raised to 60℃ and reacted for 2.8h. The organic solvent was removed under reduced pressure, and 11g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0040] 19g of glucose was added to 140g of deionized water and ultrasonically dispersed for 28min. The mixture was then transferred to a hydrothermal reactor and reacted at 178℃ for 23h. The mixture was then washed three times with ethanol and deionized water to obtain carbon spheres. 1.8g of carbon spheres were added to 280g of deionized water and dispersed. 1.3g of dopamine hydrochloride and 1.8g of adenosine triphosphate were added under continuous stirring. The pH of the system was adjusted to 8.5 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 17h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 28min. Then, 22g of zinc sulfate heptahydrate and 19.5g of sodium stannate trihydrate were added. The mixture was stirred and reacted at room temperature for 7.5h. After centrifugation and washing, the mixture was vacuum dried at 64℃ for 11.5h to obtain the composite flame-retardant reinforced material.

[0041] 2.4 g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into a fine powder and mixed with 0.95 g of propylene carbonate and 0.18 g of dispersant (model: DISPERBYK-190) for 9 minutes to prepare the curing component; 39 g of WPU-SS emulsion was mixed with 17 g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model: 0947A-60W), and then 1.4 g of glass flakes (400 mesh), 6.5 g of ammonium polyphosphate, and 1.9 g of other components were added sequentially. The following ingredients were mixed: 0.9g of composite flame-retardant reinforcing material, 0.28g of dispersant (model: DISPERBYK-190), 0.25g of wetting agent (model: BYK-348), 0.25g of defoamer (model: BYK-024), and 1.9g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model: R-566). After mixing and stirring at 1550r / min for 38min, 3.53g of curing component was added and mixed and stirred at 1950r / min for 14min to obtain the anti-corrosion and flame-retardant coating.

[0042] Example 6 40.5 g of polytetrahydrofuran ether diol (molecular weight 2000) was dehydrated under vacuum at 106 °C and -0.08 MPa for 2.6 h. The mixture was then cooled to 63 °C and protected with nitrogen. 12.2 g of isophorone diisocyanate and 0.09 g of dibutyltin dilaurate were added, and the mixture was heated to 80 °C and reacted for 2.6 h to obtain an isocyanate-terminated prepolymer. The system was then cooled to 70 °C, and 3.3 g of dimethylolpropionic acid and 8.5 g of acetone were added. The reaction was continued for 72 min, then cooled to 33 °C, and 2.5 g of triethylamine was added for neutralization for 30 min. Subsequently, 56g of deionized water was added in batches at 2000r / min for phase inversion emulsification for 26min to obtain WPU predispersant; 2.3g of cystamine dihydrochloride was dissolved in 8.5g of deionized water, and the pH was adjusted to 7.8 with 1mol / L NaOH solution. The solution was then added dropwise to the WPU predispersant at room temperature. After the addition was complete, the temperature was raised to 60℃ and reacted for 2.6h. The organic solvent was removed under reduced pressure, and 10.5g of deionized water was added and mixed to obtain an aqueous polyurethane emulsion with disulfide bonds in the main chain (WPU-SS emulsion).

[0043] 17g of glucose was added to 130g of deionized water and ultrasonically dispersed for 26min. The mixture was then transferred to a hydrothermal reactor and reacted at 175℃ for 22h. Afterward, the mixture was washed three times with ethanol and deionized water to obtain carbon spheres. 1.6g of carbon spheres were added to 260g of deionized water and dispersed. Under continuous stirring, 1.1g of dopamine hydrochloride and 1.7g of adenosine triphosphate were added, and the pH of the system was adjusted to 8.4 with 0.1mol / L Tris-HCl buffer. The mixture was stirred and reacted at room temperature for 16.5h. After centrifugation and washing, the mixture was added to 500g of deionized water and ultrasonically treated for 26min. Then, 21g of zinc sulfate heptahydrate and 19g of sodium stannate trihydrate were added sequentially. The mixture was stirred and reacted at room temperature for 7h. After centrifugation and washing, the mixture was vacuum dried at 63℃ for 11h to obtain the composite flame-retardant reinforced material.

[0044] 2.3g of 4,4'-diaminodiphenyl disulfide (CAS No.: 722-27-0) was pre-pulverized into a fine powder and mixed with 0.9g of propylene carbonate and 0.16g of dispersant (model: DISPERBYK-190) for 8 minutes to prepare the cured component; 36g WPU-SS emulsion was mixed with 16g of waterborne epoxy resin emulsion (purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model number 0947A-60W). Then, 1.3g of glass flakes (400 mesh), 6.2g of ammonium polyphosphate, 1.8g of composite flame retardant reinforcing material, 0.8g of dispersant (model number: DISPERBYK-190), 0.24g of wetting agent (model number: BYK-348), 0.2g of defoamer (model number: BYK-024), and 1.85g of titanium dioxide (purchased from Tianjin Maister Technology Co., Ltd., model number: R-566) were added sequentially. The mixture was stirred at 1450r / min for 36min. Then, 3.36g of curing component was added and the mixture was stirred at 1850r / min for 13min to obtain the anti-corrosion and flame retardant coating.

[0045] The present invention also includes comparative examples and related experiments.

[0046] Comparative Example 1 Compared with Example 3, the only difference is that no composite flame-retardant reinforcing material was added. The other preparation methods and components are completely consistent, and the anti-corrosion and flame-retardant coating is finally obtained.

[0047] Comparative Example 2 Compared with Example 3, the only difference is that a conventional waterborne polyurethane emulsion (model: FS-108C) is used instead of WPU-SS emulsion and a polyamide curing agent is used as the curing component. The other preparation methods and components are completely consistent, and the anti-corrosion and flame-retardant coating is finally obtained.

[0048] Comparative Example 3 Compared with Example 3, the only difference is that glass flakes were not added, but the other preparation methods and components are completely the same, and the anti-corrosion and flame-retardant coating is finally obtained.

[0049] Comparative Example 4 Compared with Example 3, the only difference is that the composite flame-retardant reinforcing material was prepared by dispersing 1.5g of carbon spheres in 250g of deionized water, adding 1.0g of dopamine hydrochloride and 1.6g of adenosine triphosphate under continuous stirring, adjusting the pH of the system to 8.5 with 0.1mol / L Tris-HCl buffer, stirring and reacting at room temperature for 16h, centrifuging, washing, and vacuum drying at 62℃ for 11h; other preparation methods were completely consistent with the composition, and finally the anti-corrosion and flame-retardant coating was obtained.

[0050] Performance testing To verify the comprehensive performance of the anti-corrosion and flame-retardant coatings prepared in this invention, the anti-corrosion and flame-retardant coatings prepared in Examples 1-6 and Comparative Examples 1-4 were coated onto the surface of a sandblasted Q235 low-carbon steel plate. After pre-drying at 60°C for 60 min, they were cured at 80°C for 2 h to form a film. The dry film thickness was controlled at approximately 150 μm to prepare a standard test sample. Additionally, the anti-corrosion and flame-retardant coatings prepared in Examples 1-6 and Comparative Examples 1-4 were coated onto a polytetrafluoroethylene plate and cured according to the same procedure, with the thickness controlled at approximately 0.3 mm to prepare free film strips. The following performance tests were then performed: (1) Mechanical performance test: The adhesion, flexibility and impact resistance of the standard test sample were tested according to the national standards GB / T5210-2006, GB / T1731-2020 and GB / T1732-2020 respectively. The tensile test of the free membrane sample was conducted according to the national standard GB / T1040.3-2006. The specific test results are shown in Table 1.

[0051] Table 1: Results of Mechanical Performance Tests

[0052] As shown in Table 1, the anti-corrosion and flame-retardant coatings obtained in Examples 1-6 of this invention exhibit good comprehensive performance in terms of adhesion, flexibility, impact resistance, and tensile properties. In contrast, Comparative Example 1, without the addition of composite flame-retardant reinforcing material, shows a decrease in all mechanical properties; Comparative Example 2, lacking dynamic disulfide bonds, experiences a decrease in adhesion to 5.3 MPa, flexibility to 4 mm, impact resistance to 35 cm, and elongation at break of only 108%. Comparative Example 3, without the addition of glass flakes, and Comparative Example 4, without the in-situ introduction of zinc stannate / hydroxystannate inorganic phase into the composite flame-retardant reinforcing material, also exhibit lower mechanical properties than the examples.

[0053] (2) Corrosion resistance test: Neutral salt spray tests were conducted on the standard test specimens according to national standard GB / T10125-2021, and the time when visible red rust first appeared on the main surface of the standard test specimens was recorded. In addition, to further evaluate the self-healing corrosion resistance of the present invention's specimens, an "X"-shaped scratch (approximately 50 μm wide) was made on the surface of the standard test specimens using a scratch tester, reaching the substrate. After heat treatment at 60℃ for 2 hours to trigger self-healing, the scratched specimens were then subjected to a 1000-hour neutral salt spray test according to national standard GB / T10125-2021, and the corrosion expansion width on both sides of the scratch was compared. Specific test results are shown in Table 2.

[0054] Table 2: Corrosion Resistance Test Results

[0055] As shown in Table 2, the anti-corrosion and flame-retardant coatings obtained in Examples 1-6 of this invention all exhibit good corrosion resistance, which is superior to that of Comparative Examples 1-4. Furthermore, Comparative Example 2, lacking dynamic disulfide bonds, showed red rust after 650 hours, and the corrosion spread width after scratch heat treatment reached as high as 7.2 mm, significantly inferior to Example 3 of this invention. In Comparative Example 3, without the addition of glass flakes, the time to red rust appearance was shortened to 970 hours, and the scratch corrosion spread width increased to 4.0 mm. Additionally, the anti-corrosion performance of Comparative Example 4 also decreased somewhat when the composite flame-retardant reinforcing material did not have the zinc stannate / zinc hydroxystannate inorganic phase introduced in situ.

[0056] (3) Flame retardant performance test: The limiting oxygen index, vertical burning rating and smoke density of the free membrane sample were determined according to the national standards GB / T2406.2-2009, GB / T2408-2021 and GB / T8627-2007 respectively. The specific test results are shown in Table 3.

[0057] Table 3: Flame Retardant Performance Test Results

[0058] As shown in Table 3, the anti-corrosion and flame-retardant coatings obtained in Examples 1-6 of this invention all exhibit good flame-retardant and smoke-suppressing properties, with limiting oxygen indices reaching 33.8% or higher, vertical burning ratings reaching V-0, and smoke density ratings controlled at 35 or lower. In contrast, Comparative Example 1, without the addition of composite flame-retardant reinforcing materials, showed a decrease in limiting oxygen index to 26.6%, a vertical burning rating to V-2, and a smoke density rating to 75, indicating a significant decline in flame-retardant and smoke-suppressing performance. In Comparative Example 4, without the in-situ introduction of zinc stannate / hydroxyzinc stannate inorganic phases into the composite flame-retardant reinforcing materials, the smoke density rating also significantly increased to 58, demonstrating that the zinc stannate / hydroxyzinc stannate inorganic phases also play an important role in the flame-retardant system of this invention.

[0059] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an anti-corrosion and flame-retardant coating, characterized in that, Includes the following steps: S1. Cystamine dihydrochloride was dissolved in deionized water and the pH was adjusted. Then, it was added dropwise to WPU predispersant at room temperature. After the addition was complete, the temperature was raised to react, the organic solvent was removed under reduced pressure, and deionized water was added and mixed to obtain WPU-SS emulsion. S2. Disperse carbon balls in deionized water, add dopamine hydrochloride and adenosine triphosphate under continuous stirring, adjust pH, stir reaction, centrifuge, wash, add to deionized water, sonicate, add zinc sulfate heptahydrate and sodium stannate trihydrate in sequence, stir reaction, centrifuge, wash, vacuum dry to obtain composite flame retardant reinforced material. S3. Mix WPU-SS emulsion with water-based epoxy resin emulsion, then add glass flakes, ammonium polyphosphate, composite flame-retardant reinforcing material, titanium dioxide and additives in sequence, mix and stir, then add curing components and mix and stir to obtain anti-corrosion and flame-retardant coating.

2. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, The WPU predispersant was obtained by vacuum dehydrating polytetrahydrofuran ether diol at 100-110℃ and -0.08MPa for 2-3 hours, then cooling to 60-65℃ and purging with nitrogen, adding isophorone diisocyanate and dibutyltin dilaurate, and reacting at 80℃ for 2-3 hours; then cooling the system to 70℃, adding dimethylolpropionic acid and acetone, and continuing the reaction for 60-80 minutes, then cooling to 30-35℃, adding triethylamine for neutralization for 25-35 minutes; finally, deionized water was added in batches at 2000 r / min for phase inversion emulsification for 20-30 minutes.

3. The method for preparing an anti-corrosion and flame-retardant coating according to claim 2, characterized in that, The WPU predispersant comprises the following raw materials in parts by weight: 38-42 parts polytetrahydrofuran ether diol, 11-13 parts isophorone diisocyanate, 0.05-0.12 parts dibutyltin dilaurate, 2.8-3.6 parts dimethylolpropionic acid, 6-10 parts acetone, 2.1-2.7 parts triethylamine, and 50-60 parts deionized water.

4. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, In step S1, cystamine dihydrochloride is dissolved in deionized water, and the pH is adjusted to 7.5-8.0 with a 1 mol / L NaOH solution. Then, it is added dropwise to the WPU pre-dispersion at room temperature. After the addition is complete, the temperature is raised to 60°C and reacted for 2-3 hours. The organic solvent is removed under reduced pressure, and deionized water is added and mixed to obtain WPU-SS emulsion.

5. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, The carbon spheres are obtained by ultrasonically dispersing 15-20 parts by weight of glucose into 80-150 parts by weight of deionized water for 20-30 minutes, transferring the mixture into a hydrothermal reactor, reacting it at 170-180℃ for 20-24 hours, and then washing it repeatedly with ethanol and deionized water 2-3 times.

6. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, In step S2, carbon spheres are dispersed in deionized water. Dopamine hydrochloride and adenosine triphosphate are added under continuous stirring. The pH of the system is adjusted to 8.2-8.6 with 0.1 mol / L Tris-HCl buffer. The reaction is continued at room temperature for 15-18 hours. After centrifugation and washing, the mixture is added to deionized water and sonicated for 20-30 minutes. Zinc sulfate heptahydrate and sodium stannate trihydrate are added sequentially. The reaction is continued at room temperature for 6-8 hours. After centrifugation and washing, the mixture is vacuum dried at 60-65°C for 10-12 hours to obtain the composite flame-retardant reinforced material.

7. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, The curing component is prepared by pre-pulverizing 2-2.5 parts by weight of 4,4'-diaminodiphenyl disulfide into micro powder, and mixing it with 0.8-1 parts by weight of propylene carbonate and 0.1-0.2 parts by weight of dispersant for 5-10 minutes.

8. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, The additives include 0.5 to 1.0 parts by weight of dispersant, 0.15 to 0.3 parts by weight of wetting agent, and 0.1 to 0.3 parts by weight of defoamer.

9. The method for preparing an anti-corrosion and flame-retardant coating according to claim 1, characterized in that, In step S3, WPU-SS emulsion and waterborne epoxy resin emulsion are mixed evenly, and glass flakes, ammonium polyphosphate, composite flame-retardant reinforcing material, titanium dioxide and additives are added in sequence. After mixing and stirring at 1200~1600 r / min for 30~40 min, curing components are added and mixed and stirred at 1600~2000 r / min for 10~15 min to obtain anti-corrosion and flame-retardant coating.

10. A corrosion-resistant and flame-retardant coating, characterized in that, The anti-corrosion and flame-retardant coating is prepared by the preparation method according to any one of claims 1 to 9, comprising the following raw materials in parts by weight: 28 to 42 parts WPU-SS emulsion, 12 to 18 parts waterborne epoxy resin emulsion, 0.8 to 1.5 parts glass flakes, 5 to 7 parts ammonium polyphosphate, 1.5 to 2 parts composite flame-retardant reinforcing material, 1.5 to 2 parts titanium dioxide, 2.9 to 3.7 parts curing component, and 0.75 to 1.6 parts additives; The composite flame-retardant reinforcing material comprises the following raw materials in parts by weight: 1-2 parts carbon spheres, 0.6-1.5 parts dopamine hydrochloride, 1.2-2 parts adenosine triphosphate, 18-23 parts zinc sulfate heptahydrate, and 18-20 parts sodium stannate trihydrate.

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