Antifouling paint for ships and preparation method thereof

Abstract

The invention belongs to the technical field of functional paint, and particularly relates to antifouling paint for ships and a preparation method of the antifouling paint. The invention aims to solve the problem that the existing ship antifouling paint is difficult to give consideration to both broad-spectrum antifouling effect and environmental safety. The preparation method comprises the following steps: carrying out chain extension polymerization on polycaprolactone polyol and polydimethylsiloxane glycol to obtain a block copolymer; the preparation method comprises the following steps: emulsifying and curing butenolide and polycaprolactone glycol to obtain an antifouling microcapsule, and further carrying out self-assembly crosslinking to obtain a response microcapsule; mixing the dispersing aid, the compound solvent and the functional filler to obtain a compound aid; mixing the dispersing aid, the compound solvent and the functional filler to obtain a compound aid; and performing phase separation and curing on the antifouling paint to obtain the antifouling coating. The anti-fouling paint prepared by the preparation method disclosed by the invention has a remarkable inhibition effect on attachment of fouling organisms while having good aging resistance and corrosion resistance, and is high in environmental safety.

Description

Technical Field

[0001] The invention belongs to the technical field of functional coatings, and particularly relates to an antifouling coating for ships and a preparation method thereof. Background Art

[0002] Ship antifouling coatings are special coatings applied to the underwater part of the hull to prevent or delay the attachment of marine organisms. They play a vital role in ensuring the navigation efficiency of ships, saving fuel, maintaining the hull structure and protecting the marine ecology.

[0003] The earliest antifouling coatings for ships were copper-based, and later evolved into organotin coatings and other types, gradually forming the modern ship antifouling coating system. The core function of ship antifouling coatings is to inhibit the attachment of organisms to the underwater part of the hull and maintain a smooth surface, thereby reducing navigation resistance, saving fuel, and reducing the spread of harmful substances and damage to the hull. Therefore, ship antifouling coatings can be divided into two types: biocide-releasing coatings and low-surface-energy coatings, which kill or repel marine organisms by releasing toxic chemicals or reduce surface adhesion, making it difficult for marine organisms to attach. In particular, the application of emerging biodegradable polymers and natural antifouling agents also provides new ideas for the development of ship antifouling coatings.

[0004] With increasingly stringent environmental regulations and increasing shipping requirements, the marine industry has a deeper demand for low-toxicity and long-lasting durability in marine antifouling coatings. Numerous biocides are prohibited by national laws and regulations. Producing marine antifouling coatings with broad-spectrum antifouling effectiveness and long-term durability while minimizing environmental impact remains a significant challenge for the industry.

[0005] At present, the existing antifouling coatings for ships are difficult to balance broad-spectrum antifouling effects and environmental safety, which is still a key problem facing the industry.

[0006] Therefore, an antifouling coating for ships and a preparation method thereof are proposed. Summary of the Invention

[0007] The present invention aims to provide an antifouling coating for ships and a preparation method thereof. The method comprises: subjecting polycaprolactone polyol and polydimethylsiloxane diol to chain extension polymerization to obtain a block copolymer; emulsifying and curing butenolide and polycaprolactone diol to obtain antifouling microcapsules; and further cross-linking the mixture through self-assembly to obtain responsive microcapsules; mixing a dispersing aid, a compounding solvent, and a functional filler to obtain a composite additive; and curing the antifouling coating through phase separation to obtain an antifouling coating.

[0008] To achieve the above object, the present invention provides the following technical solutions: A method for preparing an antifouling coating for ships comprises the following steps: Unless otherwise specified, the parts in the present invention refer to parts by mass, and the average molecular weight refers to the number-average molecular weight.

[0009] Polycaprolactone polyol and polydimethylsiloxane diol are subjected to chain extension polymerization to obtain a block copolymer.

[0010] The polycaprolactone polyol includes polycaprolactone diol and polycaprolactone tetraol. The average molecular weight of polycaprolactone diol is 1800-2500 g / mol, and the average molecular weight of polycaprolactone tetraol is 2000-3000 g / mol. The average molecular weight of polydimethylsiloxane diol is 2500-3000 g / mol.

[0011] Butenolide and polycaprolactone diol are emulsified and solidified to obtain antifouling microcapsules.

[0012] The raw material selection of polycaprolactone diol is consistent with the chain extension polymerization process, and its average molecular weight is 1800-2500 g / mol.

[0013] The antifouling microcapsules are cross-linked through self-assembly to obtain responsive microcapsules.

[0014] The dispersing auxiliary agent, the compounding solvent and the functional filler are mixed to obtain the composite auxiliary agent.

[0015] The compound solvent includes butanone, butyl acetate and ethyl acetate; the dispersing agents include BYK-154 and EFKA-4010; and the functional fillers include zinc phosphate and mica iron oxide.

[0016] BYK-154 is a finished dispersant manufactured by BYK, and EFKA-4010 is a finished dispersant manufactured by BASF.

[0017] The dispersing auxiliary agent, the compounding solvent and the functional filler are mixed to obtain the composite auxiliary agent.

[0018] The antifouling paint is solidified through phase separation to obtain an antifouling coating.

[0019] Preferably, the chain extension polymerization process is: 12 parts of polycaprolactone diol, 12-20 parts of polycaprolactone tetraol and 15 parts of polydimethylsiloxane diol are vacuum dried at 80°C for 2 hours, mixed under nitrogen protection, dissolved in 50 parts of butanone at 60-70°C, stirred and dropwise added with 12-15 parts of isophorone diisocyanate, fully mixed, added with 0.05 parts of dibutyltin dilaurate, heated to 80°C and reacted for 4 hours to obtain a prepolymer solution; after cooling the prepolymer solution to 60°C, 2 parts of 1,4-butanediol are added, stirred and reacted for 3 hours, anhydrous methanol is added to quench the reaction, and the residual solvent is removed by rotary distillation to obtain a block copolymer.

[0020] Preferably, the emulsification and solidification process is as follows: 15 parts of polycaprolactone diol and 5-10 parts of butenolide are dissolved in 50 parts of dichloromethane to obtain an oil phase solution; 0.3 parts of polyvinyl alcohol are dissolved in 100 parts of deionized water to obtain an aqueous phase solution; the oil phase solution is added to the aqueous phase solution at an ultrasonic frequency of 30-40 kHz, ultrasonic-assisted dispersion is performed for 5-10 minutes, and the mixture is stirred and volatilized at a speed of 500-800 rpm at 35° C. for 8 hours, centrifuged to obtain a product, and washed with deionized water to obtain antifouling microcapsules, which are in the form of a suspension with a solid content of 10-15wt%.

[0021] The average molecular weight of polyvinyl alcohol is 1500-1800 g / mol.

[0022] Preferably, the self-assembly cross-linking process is as follows: dissolving chitosan in an acetic acid solution with a mass concentration of 1 wt% to prepare a chitosan solution with a concentration of 1 mg / mL; dissolving sodium alginate and N-acylated L-homoserine lactone in deionized water to prepare a negatively charged solution with a sodium alginate concentration of 1 mg / mL and an N-acylated L-homoserine lactone concentration of 2 mg / mL. Positive charging: mixing the antifouling microcapsules with the chitosan solution, stirring at a speed of 200 rpm for 30 minutes, centrifuging and discarding the supernatant, and washing with a 1wt% acetic acid solution to obtain positively charged microcapsules; negative charging: dispersing the positively charged microcapsules in deionized water, then adding them to the negatively charged solution, stirring at a speed of 150-300 rpm for 30 minutes to obtain negatively charged microcapsules; alternating the positive charging and negative charging processes 3-5 times each, the two processes are performed alternately and the number of times is equal, taking the negatively charged microcapsules after the last negative charging treatment and dropping them into a calcium chloride aqueous solution with a mass concentration of 3wt%, centrifuging and discarding the supernatant to obtain the responsive microcapsules.

[0023] The N-acylated L-homoserine lactone is specifically N-nonanoyl-L-homoserine lactone, CAS: 177158-21-3.

[0024] Preferably, the addition amount of each component in the composite auxiliary agent is: 25 parts of butanone, 55 parts of butyl acetate, 25 parts of ethyl acetate, 2 parts of BYK-154, 3 parts of EFKA-4010, 2 parts of zinc phosphate, and 7 parts of mica iron oxide.

[0025] Preferably, the dispersing and mixing process is: adding 55-70 parts of the block copolymer to 100 parts of the composite auxiliary agent, stirring at a stirring speed of 700 rpm until fully mixed, reducing the stirring speed to 200 rpm and then adding 9 parts of the responsive microcapsules to obtain the antifouling coating.

[0026] Preferably, the phase separation curing process is as follows: diluting hexamethylene diisocyanate trimer with butyl acetate to prepare a curing mixed solution having a hexamethylene diisocyanate trimer mass concentration of 55-75 wt%; mixing 100 parts of the antifouling coating with 15 parts of the curing mixed solution at 25° C. and letting it stand for 15 minutes to obtain a cured coating; spraying the cured coating onto the surface of the hull substrate, drying at 25-35° C. for 48 hours, heating to 50° C. and drying for 12 hours, and then drying and curing at 25° C. for 168 hours to obtain the antifouling coating.

[0027] Ethyl acetate and butanone, fast-drying solvents, help the coating set quickly after spraying and prevent sagging. Butyl acetate, a slow-drying, high-boiling-point solvent, facilitates the internal migration and thermodynamic movement of polymer chains during the coating's drying and curing process. During the first drying stage, the ethyl acetate and butanone largely evaporate, transforming the paint film from a liquid to a highly viscous state. The slow-drying butyl acetate remains, maintaining the flexibility and mobility of the polymer chains. Driven by thermodynamics, the polydimethylsiloxane segments with extremely low surface energy have sufficient time to migrate from the interior of the coating to the surface of the coating; during the second drying process, the temperature increase treatment can significantly accelerate the cross-linking reaction rate of the cyano curing agent and the active segments in the block copolymer, so that the polymer network is rapidly formed, anchoring the polydimethylsiloxane structure that has self-assembled to the surface in place to prevent it from migrating again, and allowing the butyl acetate to completely evaporate, making the coating densified; during the third drying process, the cross-linking reaction of the polyurethane will continue slowly until it is complete even after the main reaction period. At this stage, the internal stress in the coating is slowly released, which is a necessary process to achieve good basic performance of the coating.

[0028] An antifouling paint for ships comprises a block copolymer, a responsive microcapsule, a dispersing aid, a compound solvent and a functional filler.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. A block copolymer prepared by chain extension polymerization of polycaprolactone diol, polycaprolactone tetraol and polydimethylsiloxane diol is used as the core film-forming resin. With the help of the degradation process of polylactone polyol, the polydimethylsiloxane segments on the coating surface are continuously exposed and renewed, ensuring lasting low surface energy and self-repairing ability, and actually achieving the effect of chemical self-polishing. This chemical self-polishing and physical self-repairing improve the long-term durability of the coating in the marine environment. At the same time, the simultaneous introduction of polycaprolactone diol and polycaprolactone tetraol gives the coating a cross-linked polymer network, giving the coating excellent solvent resistance, making it less likely to swell in the marine environment, and synergistically improving the durability and corrosion resistance of the coating.

[0030] 2. Through an emulsification-curing and self-assembly cross-linking process, a special environmentally responsive microcapsule additive with a multilayer shell was prepared. This enables on-demand, staged, cascade release of the butenolide biocide. Furthermore, by introducing polycaprolactone diol as the core material of the responsive microcapsules, the stability of the responsive microcapsules within the coating matrix was improved. In the marine environment, upon contact with seawater, the responsive microcapsules in the coating initially inhibit biofilm formation through the N-acylated L-homoserine lactone in the shell, fundamentally blocking the attachment signals of large fouling organisms. Later, the long-term sustained release of butenolide strengthens the defense line. This responsive release significantly improves the utilization efficiency of the antifouling agent and minimizes chemical emissions to the environment.

[0031] 3. Combining the interaction between the block copolymer and the functional filler in the composite additive, and through a specific phase separation curing process, the coating surface and interior are induced to undergo microphase separation, forming a low surface energy interface in situ on the coating surface, reducing the initial adhesion of fouling organisms and making them extremely easy to fall off under weak water flow. With the help of zinc phosphate additives, a dense phosphate complex film is formed at the interface between the coating and the hull substrate, effectively inhibiting the electrochemical process of corrosion. The unique scaly structure of mica iron oxide forms an overlapping physical barrier in the coating, greatly extending the path for corrosive media such as water and oxygen to penetrate into the substrate, providing an excellent physical shielding effect. The network cross-linked system formed by the block copolymer achieves good structural stability. By designing a specific type of block copolymer and a specific functional filler, and through a phase separation curing process, the present invention achieves the effect of constructing a multi-layered protective system in situ on the surface of the hull substrate, while maintaining the basic strength of the coating, greatly improving its corrosion resistance in marine environments and ensuring the excellent durability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the preparation process of the antifouling coating for ships. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention are described clearly and completely below through some embodiments and experimental examples. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Reference Figure 1 The process flow chart shown in FIG. 1 shows, the present invention provides an antifouling coating for ships and a preparation method thereof, and the technical solution is as follows:

[0035] Example 1 12 parts of polycaprolactone diol, 12 parts of polycaprolactone tetraol and 15 parts of polydimethylsiloxane diol were vacuum dried at 80°C for 2 hours, mixed under nitrogen protection, dissolved in 50 parts of butanone at 60°C, stirred and dropwise added with 12-15 parts of isophorone diisocyanate, fully mixed, added with 0.05 parts of dibutyltin dilaurate, heated to 80°C and reacted for 4 hours to obtain a prepolymer solution; after cooling the prepolymer solution to 60°C, 2 parts of 1,4-butanediol were added, stirred and reacted for 3 hours, then anhydrous methanol was added to quench the reaction, and the residual solvent was removed by rotary distillation to obtain a block copolymer.

[0036] 15 parts of polycaprolactone diol and 5 parts of butenolide were dissolved in 50 parts of dichloromethane to obtain an oil phase solution; 0.3 parts of polyvinyl alcohol were dissolved in 100 parts of deionized water to obtain an aqueous phase solution; the oil phase solution was added to the aqueous phase solution at an ultrasonic frequency of 30 kHz, and after ultrasonic-assisted dispersion for 5 minutes, the mixture was stirred and volatilized at a speed of 500 rpm at 35°C for 8 hours, and the product was centrifuged and washed with deionized water to obtain antifouling microcapsules.

[0037] Chitosan was dissolved in a 1 wt% acetic acid solution to prepare a 1 mg / mL chitosan solution. Sodium alginate and N-acylated L-homoserine lactone were dissolved in deionized water to prepare a negatively charged solution with a sodium alginate concentration of 1 mg / mL and a N-acylated L-homoserine lactone concentration of 2 mg / mL. Positive charging: The antifouling microcapsules were mixed with the chitosan solution, stirred at 200 rpm for 30 minutes, centrifuged and the supernatant discarded, and washed with a 1 wt% acetic acid solution to obtain positively charged microcapsules. Negative charging: The positively charged microcapsules were dispersed in deionized water, then added to the negatively charged solution and stirred at 150 rpm for 30 minutes to obtain negatively charged microcapsules. The positive and negative charging processes were repeated three times each. The negatively charged microcapsules after the third negative charging treatment were added dropwise to a 3 wt% calcium chloride aqueous solution, centrifuged and the supernatant discarded to obtain responsive microcapsules.

[0038] The following substances were mixed to prepare a composite additive: 25 parts of butanone, 55 parts of butyl acetate, 25 parts of ethyl acetate, 2 parts of BYK-154, 3 parts of EFKA-4010, 2 parts of zinc phosphate, and 7 parts of mica iron oxide.

[0039] 55 parts of the block copolymer were added to 100 parts of the composite auxiliary agent, and the mixture was stirred at a stirring speed of 700 rpm until fully mixed. After the stirring speed was reduced to 200 rpm, 9 parts of the responsive microcapsules were added to obtain an antifouling coating.

[0040] Hexamethylene diisocyanate trimer was diluted with butyl acetate to prepare a curing mixed solution having a hexamethylene diisocyanate trimer mass concentration of 55 wt %. 100 parts of the antifouling coating were mixed with 15 parts of the curing mixed solution at 25°C and allowed to stand for 15 minutes to obtain a cured coating. The cured coating was sprayed onto the surface of a hull substrate, dried at 25°C for 48 hours, then heated to 50°C and dried for 12 hours, and then dried and cured at 25°C for 168 hours to obtain an antifouling coating.

[0041] Examples 2-16 differ from Example 1 in operating parameters, but the other process steps and the selection range of raw materials are the same.

[0042] The specific changes in operating parameters are summarized in Tables 1 and 2.

[0043] Table 1 Operation parameter changes of Examples 1-16 (I)

[0044] Table 2 Operation parameter changes of Examples 1-16 (II)

[0045] Comparative Example 1 The difference from Example 1 is that polycaprolactone diol is used in equal parts by mass instead of polycaprolactone tetraol, and other process parameters are the same.

[0046] Comparative Example 2 The difference from Example 1 is that polydimethylsiloxane diol is not added, and other process parameters are the same.

[0047] Comparative Example 3 Different from Example 1, the chain extension polymerization process was not performed, and the polycaprolactone diol, polycaprolactone tetraol and polydimethylsiloxane diol were directly physically blended with isophorone diisocyanate to prepare the prepolymer. Other process parameters were the same.

[0048] Comparative Example 4 The difference from Example 7 is that the self-assembly cross-linking process is not performed, the response microcapsules are replaced by an equal amount of antifouling microcapsules, and the other process parameters are the same.

[0049] Comparative Example 5 The difference from Example 7 is that N-acylated L-homoserine lactone is not added, and other process parameters are the same.

[0050] Comparative Example 6 Different from Example 7, when preparing the coating, no responsive microcapsules were added, and an equal amount of butenolide was directly dispersed and mixed into the coating, and other process parameters were the same.

[0051] Comparative Example 7 The difference from Example 13 is that no functional filler is added, and other process parameters are the same.

[0052] Comparative Example 8 The difference from Example 13 is that during the phase separation curing process, only a single-stage curing at 25° C. is performed, and the other process parameters are the same.

[0053] Comparative Example 9 The difference from Example 13 is that zinc phosphate is not added, and only mica iron oxide is added as a functional filler, and other process parameters are the same.

[0054] Experimental Example 1 The durability and corrosion resistance of the antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-3 were tested in a marine environment, and the relevant results are summarized in Table 3.

[0055] The actual dry thickness of the antifouling coating used in the experiment is between 250-400µm, and the hull substrate is marine structural steel.

[0056] The coating durability test method is as follows: referring to ASTM D4060-14, a friction test is performed on the coating specimens, and the initial wear index I0 is recorded. The coating is then immersed in artificial seawater at 25°C for 30 days and 180 days, and then the friction test is repeated, respectively, to record the corresponding wear coefficients I1 and I2. Where I = [mass of specimen before wear (mg) - mass of specimen after wear (mg)] × 1000 / number of wear cycles; the friction wheel used is CS-17, and the friction pressure is 1000g.

[0057] In this scheme, the main components of artificial seawater are: sodium chloride 2.25g / L, magnesium sulfate 3.2g / L, calcium chloride 1.2g / L, sodium bicarbonate 0.2g / L, potassium chloride 0.8g / L, and the pH value is adjusted to 6.0-6.5.

[0058] The test method for the corrosion resistance of the coating is as follows: the initial coating impedance modulus R0 (Ω / cm 2 ), refer to the artificial seawater immersion method in the durability test method, test the coating impedance modulus R1 again after immersion for 180 days, and calculate the performance retention rate R1 / R0. The higher the performance retention rate, the better the corrosion resistance of the coating.

[0059] Table 3 Corrosion resistance and durability of the coatings prepared in Examples 1-6 and Comparative Examples 1-3

[0060] The R0 data corresponding to each embodiment and comparative example are as follows: Example 1: 1.44×10 8 Ω / cm2 Example 2: 1.47×10 8 Ω / cm 2 Example 3: 1.52×10 8 Ω / cm 2 Example 4: 1.46×10 8 Ω / cm 2 Example 5: 1.42×10 8 Ω / cm 2 Example 6: 1.49×10 8 Ω / cm 2 Comparative Example 1: 1.18×10 8 Ω / cm 2 Comparative Example 2: 1.51×10 8 Ω / cm 2 Comparative Example 3: 1.25×10 8 Ω / cm 2 .

[0061] As shown in Table 3, the antifouling coating prepared in Example 1 exhibited excellent performance in terms of initial wear index, wear index after 30 days of immersion, wear index after 180 days of immersion, and coating resistance retention after 180 days, demonstrating its long-term durability and corrosion resistance in marine environments. Examples 2-6 exhibited similar performance to Example 1, indicating that changes in operating parameters had little significant impact on the performance of the antifouling coatings prepared by the present invention.

[0062] Comparative Example 1 replaces polycaprolactone tetraol with polycaprolactone diol of equal mass fraction, resulting in the coating lacking the cross-linked polymer network that polycaprolactone tetraol can form. This change causes the wear index I2 of the coating after long-term immersion to rise significantly, and the performance retention rate also drops from 94.2% to 90.4%. This shows that the introduction of polycaprolactone tetraol is crucial for building a stable cross-linked network structure, which gives the coating excellent solvent resistance, making it difficult to swell in a marine environment, thereby synergistically improving the durability and corrosion resistance of the coating. Comparative Example 2 does not add polydimethylsiloxane diol, which directly causes the wear index I2 of the coating to rise significantly after 180 days. Polydimethylsiloxane diol is a key component in forming low surface energy and self-repairing ability segments in block copolymers. Lack of polydimethylsiloxane segments makes it difficult for the coating surface to be continuously exposed and updated through the self-polishing degradation process, thereby weakening the coating's lasting low surface energy and self-repairing ability, causing its long-term durability to decline. Comparative Example 3 does not carry out the chain extension polymerization process, but instead physically blends polycaprolactone diol, polycaprolactone tetraol and polydimethylsiloxane diol with isophorone diisocyanate to prepare a prepolymer. This method fails to form the specific block copolymer structure described in beneficial effect 1, resulting in a comprehensive deterioration of various performance indicators. The initial wear index I0 shows a significant increase, and the wear index I2 also increases significantly after 180 days, and the performance retention rate drops sharply from 94.2% to 78.9%. This fully demonstrates the necessity of the specific block copolymer prepared by chain extension polymerization as the core film-forming resin. This shows that, on the basis of the formation of this block tool structure, the coating can effectively realize the self-polishing degradation process of the polylactone polyol and continuously expose and renew the polydimethylsiloxane segments on the coating surface, thereby ensuring the coating's lasting low surface energy, self-repair ability and long-term durability.

[0063] In summary, the present invention successfully prepared a block copolymer with a specific structure as the core film-forming resin by chain extension polymerization of polycaprolactone diol, polycaprolactone tetraol and polydimethylsiloxane diol. Among them, the introduction of polycaprolactone tetraol forms a key cross-linking network, which provides structural stability and solvent resistance of the coating; polydimethylsiloxane diol gives the coating the characteristics of low surface energy; and the block structure formed by chain extension polymerization ensures that the self-polishing degradation of the polycaprolactone part can effectively renew the polydimethylsiloxane segments on the surface. These three components and the specific polymerization process produce a significant synergistic effect: the combination of chemical self-polishing and physical self-repair, as well as the structural stability provided by the cross-linking network, together greatly improve the long-term durability and corrosion resistance of the coating in the marine environment, and achieve an excellent anti-fouling effect.

[0064] Experimental Example 2 The antifouling coatings prepared in Examples 7-12 and Comparative Examples 4-6 were tested for their short-term and long-term bioinhibition rates and biocide release rates in a marine environment. The relevant results are summarized in Table 4.

[0065] The test method for short-term and long-term bioinhibition rates is as follows: refer to the experimental method of GBT 5370-2007 standard, use the scoring standard of 7.2 antifouling evaluation therein, and record the antifouling scores of the coating samples after three months and one year respectively.

[0066] The test method for the release rate of the biocide is as follows: a coating sample of size 150 mm × 75 mm is immersed in artificial seawater with a volume of V = 50 L, and the concentration of butenolide in the artificial seawater is measured after one month at 25°C. t (µg / L), and calculate the average release rate of the biocide R t =(C t × V) / (A×△t), in this scheme, A is the coating test area, and △t is the sampling interval (days).

[0067] Table 4 Biological inhibition rate and biocide release rate of the coatings prepared in Examples 7-12 and Comparative Examples 4-6

[0068] As shown in Table 4, the antifouling coating prepared in Example 7 showed excellent antifouling performance after three months and one year, reaching 95 points and 92 points respectively, while the average release rate of the biocide was maintained at 1.55 μg / cm 2 / day, which indicates that it has efficient and long-lasting antifouling performance and good biocide release control ability.

[0069] Compared with Example 7, Comparative Example 4 did not undergo the self-assembly crosslinking process and directly used antifouling microcapsules without multilayer shell construction instead of the response microcapsules. Its antifouling score after three months was only 74 points, far lower than that of Example 7, and the biocide release rate was as high as 5.26µg / cm 2 / day. This shows that responsive microcapsules with multilayer shells and environmental responsiveness, prepared through emulsification, solidification, and self-assembly and cross-linking processes, are crucial for achieving efficient utilization and phased release of biocides. The lack of a multilayer shell constructed through self-assembly and cross-linking makes it impossible to effectively regulate the release of butenolide. It also lacks the N-acylated L-homoserine lactone layer, which inhibits biofilms in the early stages, resulting in poor initial antifouling performance and rapid biocide loss. Comparative Example 5 does not add N-acylated L-homoserine lactone during the self-assembly and cross-linking process. Its antifouling score was 75 points after three months, but dropped sharply to 69 points after one year. N-acylated L-homoserine lactone is a key component in the responsive microcapsule shell layer for early inhibition of biofilm formation. Without this component, the coating is unable to fundamentally prevent the attachment signals of large fouling organisms during initial contact with seawater, resulting in a significant decrease in early antifouling performance and affecting the long-term antifouling effect. Although the release rate of butenolide is similar to that of Example 7, the overall antifouling effect is significantly weakened. This highlights the key role of N-acylated L-homoserine lactone in achieving a staged, cascaded release antifouling mechanism. Comparative Example 6 did not add responsive microcapsules, but instead dispersed and mixed an equal amount of butenoic acid lactone directly into the coating. Although its antifouling score reached 85 points after three months, it dropped sharply to 65 points after one year, and the biocide release rate soared to 15.39µg / cm 2 This indicates that without the encapsulation and responsive release mechanism of microcapsules, the butenolide biocide would dissolve rapidly and in large quantities, resulting in huge waste and reducing the utilization efficiency of the antifouling agent. It also fails to provide long-term antifouling protection and poses a greater risk of chemical emissions to the environment.

[0070] In summary, the present invention prepares antifouling microcapsules by emulsification and solidification process with butenolide and polycaprolactone diol, and then assembles chitosan, sodium alginate and N-acylated L-homoserine lactone layer by layer through self-assembly cross-linking process to construct responsive microcapsules with multi-layer shell and environmental responsiveness. This special microcapsule additive works synergistically with each component therein. In the marine environment, after the coating contacts seawater, the N-acylated L-homoserine lactone in the shell first plays a role, effectively inhibiting the formation of early biofilms; Subsequently, the microcapsules slowly and continuously release the core butenolide biocide to consolidate the antifouling effect. This on-demand, staged cascade release mechanism significantly improves the utilization efficiency of the antifouling agent and the long-term antifouling performance of the coating, while minimizing the discharge of chemicals to the marine environment.

[0071] Experimental Example 3 The durability and corrosion resistance of the antifouling coatings prepared in Examples 13-16 and Comparative Examples 7-9 were tested in a marine environment. The relevant results are summarized in Table 5.

[0072] The test methods for coating durability and coating corrosion resistance refer to Experimental Example 1.

[0073] Table 5 Corrosion resistance and durability of the coatings prepared in Examples 13-16 and Comparative Examples 7-9

[0074] As shown in Table 5, the antifouling coating prepared in Example 13 exhibited excellent performance in terms of initial wear index, wear index after 30 days of immersion, wear index after 180 days of immersion, and coating resistance retention after 180 days, fully demonstrating its excellent durability and corrosion resistance in marine environments. Compared with Example 13, Comparative Example 7, which did not add functional fillers, exhibited a significant overall decline in coating performance. After 180 days, the wear index (I2) significantly increased compared to Example 1, and the performance retention rate also plummeted from 93.4% to 78.3%. This demonstrates that the introduction of functional fillers has a decisive impact on the durability and corrosion resistance of the coating. Without the electrochemical corrosion inhibition of zinc phosphate and the physical shielding effect of micaceous iron oxide, the overall protective capability of the coating is significantly deficient. Comparative Example 8 modified the phase separation curing process, employing a single-stage curing at 25°C, while Example 13 employed a three-stage, specific drying and curing process. The wear index (I2) and performance retention after 180 days of Comparative Example 8 were inferior to those of Example 13. This shows that a specific phase separation curing process is crucial for inducing ideal microphase separation on the surface and inside of the coating. This microphase separation can form a low surface energy interface in situ on the coating surface, reduce the initial adhesion of fouling organisms, and optimize the overall structure of the coating, thereby synergistically improving the durability and corrosion resistance of the coating. Comparative Example 9 only adds micaceous iron oxide to the functional filler without adding zinc phosphate. Although its initial and long-term wear indexes are similar to those of Example 13, the performance retention rate is significantly reduced from 93.4% in Example 13 to 82.7%. The key role of zinc phosphate is to form a dense phosphate complex film at the interface between the interior of the coating and the hull substrate, effectively inhibiting the electrochemical process of corrosion. In the absence of zinc phosphate, even if the physical shielding effect of micaceous iron oxide still exists, the ability of the coating to resist electrochemical corrosion is greatly reduced, which directly proves the unique and important synergistic contribution of zinc phosphate in improving corrosion resistance.

[0075] In summary, the present invention achieves synergistic enhancement through specific block copolymers, functional fillers in composite additives, and a specific phase separation curing process. The network cross-linking system formed by the block copolymer ensures good structural stability of the coating. The specific phase separation curing process induces the formation of a low surface energy interface on the coating surface, reducing the attachment of fouling organisms. Zinc phosphate forms a phosphate complex film at the substrate interface, providing electrochemical corrosion protection; at the same time, the unique scaly structure of mica iron oxide forms overlapping physical barriers in the coating, extending the penetration path of the corrosive medium. These technical means and materials interact with each other to construct a multi-level protection system in situ on the surface of the hull substrate, which ensures the basic strength of the coating while significantly improving its durability and corrosion resistance in the marine environment.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an antifouling coating for ships, characterized in that: The preparation method is as follows: Polycaprolactone polyol and polydimethylsiloxane diol are subjected to chain extension polymerization to obtain a block copolymer; Butenolide and polycaprolactone diol are emulsified and solidified to obtain antifouling microcapsules; cross-linking the antifouling microcapsules through self-assembly to obtain responsive microcapsules; Mixing a dispersing agent, a compounding solvent and a functional filler to obtain a composite agent; Wherein, the functional filler includes zinc phosphate and mica iron oxide; Wherein, the compound solvent comprises: butanone, butyl acetate and ethyl acetate; Dispersing and mixing the responsive microcapsules, the composite auxiliary agent and the block copolymer to obtain an antifouling coating; The antifouling paint is solidified through phase separation to obtain an antifouling coating.

2. The method for preparing an antifouling coating for ships according to claim 1, wherein: The chain extension polymerization process comprises: vacuum drying the polycaprolactone polyol and the polydimethylsiloxane diol, mixing them under nitrogen protection, dissolving them in butanone, stirring, adding isophorone diisocyanate, fully mixing, adding dibutyltin dilaurate, heating and stirring to react to obtain a prepolymer solution; cooling the prepolymer solution, adding 1,4-butanediol, stirring to react, adding anhydrous methanol to quench the reaction, and removing the residual solvent by rotary distillation to obtain the block copolymer.

3. The method for preparing an antifouling coating for ships according to claim 1, wherein: The emulsification and solidification process comprises: dissolving the polycaprolactone diol and the butenolide in dichloromethane to obtain an oil phase solution; dissolving polyvinyl alcohol in deionized water to obtain an aqueous phase solution; adding the oil phase solution to the aqueous phase solution under ultrasonic assistance, stirring and volatilizing the mixture, centrifuging to obtain a product, and washing with deionized water to obtain the antifouling microcapsules.

4. The method for preparing an antifouling coating for ships according to claim 1, wherein: The self-assembly cross-linking process is as follows: the antifouling microcapsules are alternately positively charged and negatively charged, the two processes are performed alternately and the number of times is equal, the treated reaction product is added dropwise into a calcium chloride aqueous solution, and the supernatant is discarded by centrifugation to obtain the responsive microcapsules.

5. The method for preparing an antifouling coating for ships according to claim 4, characterized in that: The positive charge conversion process comprises: dissolving chitosan in acetic acid solution to prepare chitosan solution; mixing the antifouling microcapsules with the chitosan solution, stirring, centrifuging, discarding the supernatant, and washing.

6. The method for preparing an antifouling coating for ships according to claim 4, characterized in that: The negative charge process is as follows: sodium alginate and N-acylated L-homoserine lactone are dissolved in deionized water to prepare a negative charge solution; the antifouling microcapsules that have undergone the positive charge treatment are dispersed in deionized water, and then added to the negative charge solution and stirred.

7. The method for preparing an antifouling coating for ships according to claim 1, wherein: The dispersing and mixing process comprises: adding the block copolymer to the composite auxiliary agent, stirring and mixing, reducing the stirring speed and adding the responsive microcapsules to obtain the antifouling coating.

8. The method for preparing an antifouling coating for ships according to claim 1, wherein: The phase separation and curing process comprises: diluting hexamethylene diisocyanate trimer with butyl acetate to prepare a curing mixed liquid; mixing the antifouling coating with the curing mixed liquid and allowing the mixture to stand to obtain a cured coating; spraying the cured coating onto the surface of a hull substrate, and drying and curing the coating in sections to obtain the antifouling coating.

9. An antifouling coating for ships, characterized in that: The antifouling paint for ships is prepared by the preparation method according to any one of claims 1 to 8; the antifouling paint for ships comprises: block copolymers, responsive microcapsules, a dispersing aid, a compounded solvent and a functional filler.

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