Antifouling paint for ships and method for producing the same

Abstract

The present application belongs to the technical field of functional coating, and particularly relates to a kind of marine antifouling coating and its preparation method.The present application aims to solve the problem that the existing marine antifouling coating is difficult to consider the broad-spectrum antifouling effect and environmental safety.The present application polymerizes block copolymer by chain extension of polycaprolactone polyol and polydimethylsiloxane diol;Antifouling microcapsules are obtained by emulsification and curing of butenolide and polycaprolactone diol, and further obtained by self-assembly crosslinking;Composite additives are obtained by mixing dispersing aids, complex solvents and functional fillers;Composite additives are obtained by mixing dispersing aids, complex solvents and functional fillers;Antifouling coating is obtained by phase separation and curing of antifouling coating.The antifouling coating prepared by the present application has good aging resistance and corrosion resistance, and has significant inhibitory effect on the attachment of fouling organisms, and high environmental safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional coatings, and particularly relates to a ship antifouling coating and a preparation method thereof. BACKGROUND

[0002] Ship antifouling coating is a special coating applied to the underwater part of the ship body to prevent or delay the attachment of marine organisms, which plays a crucial role in ensuring the sailing efficiency of the ship, saving fuel, maintaining the structure of the ship body and protecting the marine ecology.

[0003] The earliest ship antifouling coating is a copper-based antifouling coating, followed by various types of organotin coatings, gradually forming a modern ship antifouling coating system. The core function of ship antifouling coating is to inhibit the attachment of organisms on the underwater part of the ship body and maintain the smoothness of the ship body surface, thereby reducing the sailing resistance, saving fuel and reducing the spread of harmful substances and damage to the ship body. Therefore, ship antifouling coatings can be divided into two types: biocide release type coatings and low surface energy coatings, which respectively kill or repel marine organisms by releasing toxic chemicals or reduce the adhesion of marine organisms on the surface. In particular, the application of emerging biodegradable polymers and natural antifouling agents also provides a new way of thinking for the development of ship antifouling coatings.

[0004] With the increasing strictness of environmental regulations and the improvement of shipping requirements, the shipbuilding industry has a deeper demand for low toxicity and long-term durability of ship antifouling coatings. Various types of biocides prohibited by laws and regulations are numerous, and how to obtain ship antifouling coatings with broad-spectrum antifouling effect and long-term durability while minimizing environmental impact is still a major problem that the industry needs to solve.

[0005] At present, the existing ship antifouling coatings still face a key problem of balancing broad-spectrum antifouling effect and environmental safety.

[0006] Therefore, a ship antifouling coating and a preparation method thereof are proposed. SUMMARY

[0007] The purpose of the present application is to provide a ship antifouling coating and a preparation method thereof. In the present application, polycaprolactone polyol and polydimethylsiloxane diol are chain-extended and polymerized to obtain a block copolymer; butenolide and polycaprolactone diol are emulsified and cured to obtain antifouling microcapsules, which are further crosslinked by self-assembly to obtain responsive microcapsules; a dispersing aid, a complex solvent and a functional filler are mixed to obtain a complex aid; and the antifouling coating is cured by phase separation to obtain an antifouling coating.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0009] A preparation method of a ship antifouling coating, comprising the following steps:

[0010] The parts in the present application refer to mass parts, and the average molecular weight refers to index molecular weight, unless otherwise specified.

[0011] The polybutylene succinate polyol and the polydimethylsiloxane diol are chain-extended and polymerized to obtain a block copolymer.

[0012] The polybutylene succinate polyol includes polybutylene succinate diol and polybutylene succinate tetrol, the average molecular weight of the polybutylene succinate diol is 1800-2500 g / mol, and the average molecular weight of the polybutylene succinate tetrol is 2000-3000 g / mol.

[0013] The butenolide and the polybutylene succinate diol are emulsified and cured to obtain antifouling microcapsules.

[0014] The raw material of the polybutylene succinate diol is selected to be consistent with the chain extension and polymerization process, and the average molecular weight is 1800-2500 g / mol.

[0015] The antifouling microcapsules are crosslinked by self-assembly to obtain responsive microcapsules.

[0016] The dispersing aid, the complexing solvent, and the functional filler are mixed to obtain a composite aid.

[0017] The complexing solvent includes butanone, butyl acetate, and ethyl acetate; the dispersing aid includes BYK-154 and EFKA-4010; and the functional filler includes zinc phosphate and mica iron oxide.

[0018] BYK-154 is a finished product dispersant produced by BYK Company, and EFKA-4010 is a finished product dispersant produced by BASF Company.

[0019] The dispersing aid, the complexing solvent, and the functional filler are mixed to obtain a composite aid.

[0020] The antifouling coating is cured by phase separation to obtain an antifouling coating layer.

[0021] Preferably, the chain extension and polymerization process is as follows: 12 parts of polybutylene succinate diol, 12-20 parts of polybutylene succinate tetrol, and 15 parts of polydimethylsiloxane diol are vacuum dried at 80°C for 2 hours, then mixed under nitrogen protection, dissolved in 50 parts of butanone at 60-70°C, stirred and added with 12-15 parts of isophorone diisocyanate dropwise, then 0.05 parts of dibutyltin dilaurate is added after fully mixed, heated to 80°C and reacted for 4 hours to obtain a prepolymer solution; the prepolymer solution is cooled to 60°C, 2 parts of 1,4-butanediol is added, stirred and reacted for 3 hours, then anhydrous methanol is added to quench the reaction, and the residual solvent is removed by rotary evaporation to obtain a block copolymer.

[0022] Preferably, the process of emulsification and solidification 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 is dissolved in 100 parts of deionized water to obtain an aqueous phase solution; the oil phase solution is added to the aqueous phase solution under an ultrasonic frequency of 30-40 kHz, and ultrasonic-assisted dispersion is performed for 5-10 minutes; then the mixture is stirred at a speed of 500-800 rpm at 35°C for 8 hours to volatilize, and the product is obtained by centrifugation; after washing with deionized water, the antifouling microcapsules are obtained, which are in the form of a suspension with a solid content of 10-15 wt%.

[0023] Preferably, the average molecular weight of the polyvinyl alcohol is 1500-1800 g / mol.

[0024] Preferably, the process of self-assembly and crosslinking is as follows: chitosan is dissolved in an acetic acid solution with a mass concentration of 1 wt% to prepare a chitosan solution with a concentration of 1 mg / mL; sodium alginate and N-acylated L-homoserine lactone are dissolved in deionized water to prepare a negative charge solution with a sodium alginate concentration of 1 mg / mL and an N-acylated L-homoserine lactone concentration of 2 mg / mL. Positive charging: the antifouling microcapsules are mixed with the chitosan solution, stirred at a speed of 200 rpm for 30 min, and then centrifuged to discard the supernatant; after washing with a 1 wt% acetic acid solution, positively charged microcapsules are obtained; negative charging: the positively charged microcapsules are dispersed in deionized water, and then the negative charge solution is added; after stirring at a speed of 150-300 rpm for 30 min, negatively charged microcapsules are obtained; the processes of positive charging and negative charging are alternately repeated for 3-5 times, and the two processes are alternately performed and the number of times is equal; the negatively charged microcapsules after the last negative charging treatment are added dropwise into a 3 wt% calcium chloride aqueous solution, and the supernatant is discarded by centrifugation to obtain the responsive microcapsules.

[0025] Preferably, the N-acylated L-homoserine lactone is N-nonanoyl-L-homoserine lactone, CAS: 177158-21-3.

[0026] Preferably, the addition amount of each component in the composite additive is as follows: 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.

[0027] Preferably, the process of dispersion and mixing is as follows: 55-70 parts of block copolymer is added to 100 parts of the composite additive, and stirred at a stirring speed of 700 rpm until fully mixed; then the stirring speed is reduced to 200 rpm, and 9 parts of the responsive microcapsules are added to obtain the antifouling paint.

[0028] Preferably, the process of phase separation and curing is as follows: hexamethylene diisocyanate trimer is diluted with butyl acetate to prepare a curing mixed solution with a mass concentration of 55-75wt% of hexamethylene diisocyanate trimer; 100 parts of the antifouling coating is mixed with 15 parts of the curing mixed solution at 25 DEG C and then left for 15 minutes to obtain a matured coating; the matured coating is sprayed onto the surface of a ship body substrate, dried at 25-35 DEG C for 48 hours, then heated to 50 DEG C for 12 hours, and then dried and cured at 25 DEG C for 168 hours to obtain an antifouling coating.

[0029] In the formula, ethyl acetate and butanone are used as fast-drying solvents, which can make the coating quickly shape after spraying to prevent sagging; butyl acetate is used as a slow-drying high-boiling solvent, which can help to realize the internal migration and thermodynamic movement of polymer segments during the drying and curing process of the coating. In the first stage of the drying process, most of the ethyl acetate and butanone volatilize, and the paint film changes from a liquid state to a high-viscosity state, and the slow-drying butyl acetate still exists, maintaining the flexibility and movement ability of the polymer segments. Under the driving of thermodynamics, the polydimethylsiloxane segments with extremely low surface energy have sufficient time to migrate from the inside of the coating to the surface of the coating; in the second stage of the drying process, the heating treatment can significantly accelerate the crosslinking reaction rate of the cyan curing agent and the active segments in the block copolymer, so that the polymer network is quickly formed, the polydimethylsiloxane structure that has self-assembled to the surface is anchored in place to prevent its migration, and the butyl acetate is also completely volatilized to densify the coating; in the third stage of the drying process, the crosslinking reaction of polyurethane will slowly proceed until complete even after the main reaction period ends, and in this stage, the internal stress in the coating is slowly released, which is a necessary process to realize good basic performance of the coating.

[0030] An antifouling coating for a ship includes a block copolymer, a responsive microcapsule, a dispersion aid, a compounded solvent and a functional filler.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1. The block copolymer prepared by chain extension polymerization of polycaprolactone diol, polycaprolactone tetrol and polydimethylsiloxane diol is used as the core film-forming resin, and the polydimethylsiloxane segments on the surface of the coating are constantly exposed and renewed through the degradation process of the polycaprolactone polyol, so that the long-term low surface energy and self-repairing ability are ensured, and the effect of chemical self-polishing is actually achieved. 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 tetrol enables the coating to have a crosslinked polymer network, which endows the coating with excellent solvent resistance, so that the coating is not easy to swell in the marine environment, and the durability and corrosion resistance of the coating are improved.

[0033] 2. A special microcapsule additive with multi-layer shell and environmental responsiveness is prepared by emulsification solidification process and self-assembly crosslinking process, realizing on-demand and staged cascade release of butenolide biocide, and the stability of the responsive microcapsule in the coating matrix is improved by introducing polycaprolactone diol as the core material of the responsive microcapsule. In the marine environment, the responsive microcapsule in the coating contacts seawater, early-stage N-acylated L-homoserine lactone in the shell layer inhibits the formation of biofilm, and the attachment signal of large-scale fouling organisms is prevented from the root; and late-stage long-acting butenolide is used to consolidate the defense line. This responsive release greatly improves the utilization efficiency of antifouling agents and maximally reduces the chemical emissions to the environment.

[0034] 3. The interaction of block copolymer and functional fillers in composite additives is combined, and microphase separation occurs on the surface and inside of the coating through the phase separation solidification process of a specific process, a layer of low surface energy interface is formed in situ on the surface of the coating, the initial adhesion of the fouling organisms is reduced, and they are easily detached under weak water flow; a dense phosphate complex film is formed on the interface between the coating and the ship body substrate by means of zinc phosphate additive, effectively inhibiting the electrochemical process of corrosion; and the unique flaky structure of mica iron oxide forms an overlapping physical barrier in the coating, greatly prolonging the path of corrosion media such as water and oxygen penetrating into the substrate, playing an excellent physical shielding effect, and realizing good structural stability by means of the reticular crosslinking system formed by the block copolymer. By designing specific types of block copolymers and specific functional fillers, and through the phase separation solidification process, the invention realizes the effect of constructing a multi-layer protection system in situ on the surface of the ship body substrate, greatly improving the corrosion resistance of the coating in the marine environment while ensuring the basic strength of the coating, and ensuring the excellent durability of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The process flow chart for preparing the antifouling coating for ships in the invention is shown in the figure. DETAILED DESCRIPTION

[0036] The technical solutions of the invention will be described below in a clear and complete manner through some embodiments and experimental examples. Obviously, the described embodiments are only a part of the embodiments of the invention, not all the embodiments. Based on the embodiments in the invention, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the invention.

[0037] REFERENCE Figure 1 The process flow chart is shown in the figure. The invention provides an antifouling coating for ships and a preparation method thereof, and the technical solutions are as follows:

[0038] Embodiment 1

[0039] After 12 parts of polycaprolactone diol, 12 parts of polycaprolactone tetrol and 15 parts of polydimethylsiloxane diol are vacuum dried at 80°C for 2 hours, they are mixed under nitrogen protection, dissolved in 50 parts of butanone at 60°C, stirred and 12-15 parts of isophorone diisocyanate is added dropwise, 0.05 parts of dibutyltin dilaurate is added after mixing thoroughly, the temperature is raised to 80°C and the reaction is carried out for 4 hours to obtain a prepolymer solution; after the prepolymer solution is cooled to 60°C, 2 parts of 1,4-butanediol is added, stirred and reacted for 3 hours, anhydrous methanol is added to quench the reaction, and the residual solvent is removed by rotary evaporation to obtain a block copolymer.

[0040] 15 parts of polycaprolactone diol and 5 parts of butenolide are dissolved in 50 parts of dichloromethane to obtain an oil phase solution; 0.3 parts of polyvinyl alcohol is dissolved in 100 parts of deionized water to obtain an aqueous phase solution; the oil phase solution is added to the aqueous phase solution under an ultrasonic frequency of 30 kHz, ultrasonic assisted dispersion is carried out for 5 minutes, the mixture is stirred at a speed of 500 rpm at 35°C for 8 hours, and the product is obtained by centrifugation, and the anti-fouling microcapsules are obtained after washing with deionized water.

[0041] Chitosan is dissolved in an acetic acid solution with a mass concentration of 1 wt% to prepare a chitosan solution with a concentration of 1 mg / mL; sodium alginate and N-acylated L-homoserine lactone are dissolved in deionized water to prepare a negative charge solution with a sodium alginate concentration of 1 mg / mL and an N-acylated L-homoserine lactone concentration of 2 mg / mL. Positive charging: the anti-fouling microcapsules are mixed with the chitosan solution, stirred at a speed of 200 rpm for 30 min, the supernatant is discarded by centrifugation, and the positively charged microcapsules are obtained after washing with a 1 wt% acetic acid solution; negative charging: the positively charged microcapsules are dispersed in deionized water, and then added to the negative charge solution, stirred at a speed of 150 rpm for 30 min to obtain negatively charged microcapsules; the positive charging and negative charging processes are repeated alternately for 3 times, the two processes are alternately carried out, and the negatively charged microcapsules after the third negative charging treatment are added dropwise into a calcium chloride aqueous solution with a mass concentration of 3 wt%, the supernatant is discarded by centrifugation to obtain responsive microcapsules.

[0042] The following are 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.

[0043] 9 parts of responsive microcapsules are added to 100 parts of the composite additive under stirring at a stirring speed of 700 rpm until fully mixed, the stirring speed is reduced to 200 rpm, and 9 parts of responsive microcapsules are added to obtain an anti-fouling coating.

[0044] The hexamethylene diisocyanate trimer is diluted with butyl acetate to prepare a curing mixture with a mass concentration of 55wt% of hexamethylene diisocyanate trimer; 100 parts of the antifouling coating is mixed with 15 parts of the curing mixture at 25°C and left to stand for 15 min to obtain a matured coating; the matured coating is sprayed onto the surface of the ship body substrate, dried at 25°C for 48 hours, then heated to 50°C for 12 hours, and then dried and cured at 25°C for 168 hours to obtain an antifouling coating.

[0045] Examples 2-16 differ from Example 1 in the operating parameters, and the selection ranges of other process steps and raw materials are the same.

[0046] The specific operating parameter changes are summarized in Tables 1-2.

[0047] Table 1 Operating parameter changes of Examples 1-16 (I)

[0048]

[0049] Table 2 Operating parameter changes of Examples 1-16 (II)

[0050]

[0051] Comparative Example 1

[0052] Different from Example 1, the same mass fraction of polycaprolactone diol is used to replace polycaprolactone tetrol, and other process parameters are the same.

[0053] Comparative Example 2

[0054] Different from Example 1, no polydimethylsiloxane diol is added, and other process parameters are the same.

[0055] Comparative Example 3

[0056] Different from Example 1, no chain extension polymerization process is performed, and the polycaprolactone diol, polycaprolactone tetrol and polydimethylsiloxane diol are directly physically blended with isophorone diisocyanate to prepare a prepolymer, and other process parameters are the same.

[0057] Comparative Example 4

[0058] Different from Example 7, no self-assembly crosslinking process is performed, and an equal amount of antifouling microcapsules is used to replace responsive microcapsules, and other process parameters are the same.

[0059] Comparative Example 5

[0060] Different from Example 7, no N-acylated L-homoserine lactone is added, and other process parameters are the same.

[0061] Comparative Example 6

[0062] Different from Example 7, in the preparation of the coating, no responsive microcapsules were added, and an equivalent amount of butenolide was directly dispersed and mixed into the coating, and other process parameters were the same.

[0063] Comparative Example 7

[0064] Different from Example 13, no functional filler was added, and other process parameters were the same.

[0065] Comparative Example 8

[0066] Different from Example 13, in the phase separation and curing process, only single-stage curing at 25°C was performed, and other process parameters were the same.

[0067] Comparative Example 9

[0068] Different from Example 13, no zinc phosphate was added, and only mica iron oxide was added as a functional filler, and other process parameters were the same.

[0069] Experimental Example 1

[0070] The durability and corrosion resistance of the antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-3 in the marine environment were tested, and the related results are summarized in Table 3.

[0071] The dry thickness of the experimental antifouling coating was between 250-400µm, and the ship body substrate was a marine structural steel.

[0072] The test method for coating durability was as follows: referring to the standard of ASTM D4060-14, the abrasion test was performed on the coating sample, the initial wear index I0was recorded, the coating was soaked in artificial seawater, and after 30 days and 180 days of soaking at 25°C, the abrasion test was performed again, and the wear coefficients I1and I2were recorded. Among them, I=[sample mass before wear (mg)-sample mass after wear (mg)]x1000 / abrasion cycle number; the friction wheel was CS-17, and the friction pressure was 1000g.

[0073] In this scheme, the main components of the artificial seawater were as follows: 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 was adjusted to 6.0-6.5.

[0074] The test method for coating corrosion resistance was as follows: the initial coating impedance modulus R0(Ω / cm2) of the coating sample was tested, referring to the soaking method of the artificial seawater in the durability test method, the coating impedance modulus R1was tested again after 180 days of soaking, the performance retention rate R1 / R0was calculated, the higher the performance retention rate, the better the coating corrosion resistance. 2

[0075] ​Table 3 Corrosion resistance and durability of the coating prepared in Examples 1-6 and Comparative Examples 1-3

[0076]

[0077] The R0 data corresponding to each example and comparative example is as follows:

[0078] Example 1: 1.44 x 10 8 Ω / cm 2 Example 2: 1.47 x 10 8 Ω / cm 2 Example 3: 1.52 x 10 8 Ω / cm 2 Example 4: 1.46 x 10 8 Ω / cm 2 Example 5: 1.42 x 10 8 Ω / cm 2 Example 6: 1.49 x 10 8 Ω / cm 2 Comparative Example 1: 1.18 x 10 8 Ω / cm 2 Comparative Example 2: 1.51 x 10 8 Ω / cm 2 Comparative Example 3: 1.25 x 10 8 Ω / cm 2 .

[0079] As shown in the data in Table 3, the antifouling coating prepared in Example 1 exhibits excellent performance in terms of initial abrasion index, abrasion index after 30 days of immersion, abrasion index after 180 days of immersion, and retention rate of coating resistance performance after 180 days, showing long-term durability and corrosion resistance in marine environments. Examples 2-6 and Example 1 have similar performance, indicating that partial changes in operating parameters have little effect on the performance of the antifouling coating formed by the antifouling coating prepared in the present application.

[0080] Comparative Example 1 replaces polycaprolactone tetrol with equal mass fraction of polycaprolactone diol, resulting in the absence of cross-linked polymer network formed by polycaprolactone tetrol in the coating. This change leads to a significant increase in the abrasion index I2 after long-term immersion, and the performance retention rate also decreases from 94.2% to 90.4%. This indicates that the introduction of polycaprolactone tetrol is crucial for the construction of a stable cross-linked network structure, which endows the coating with excellent solvent resistance, making it less likely to swell in marine environments, thereby synergistically improving the durability and corrosion resistance of the coating. Comparative Example 2 does not add polydimethylsiloxane diol, directly leading to a significant increase in the abrasion index I2 of the coating after 180 days. Polydimethylsiloxane diol is a key component for forming low surface energy and self-repairing chain segments in the block copolymer. Without polydimethylsiloxane segments, the coating surface is difficult to continuously expose and renew through the self-polishing degradation process, thereby weakening the coating's persistent low surface energy and self-repairing ability, leading to a decrease in long-term durability. Comparative Example 3 does not undergo chain extension polymerization, but instead physically blends polycaprolactone diol, polycaprolactone tetrol, 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, leading to a comprehensive deterioration in performance indicators. The initial abrasion index I0 increases significantly, the abrasion index I2 after 180 days also increases significantly, and the performance retention rate drops significantly 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 indicates that, based on the formation of this block structure, the coating can effectively implement the self-polishing degradation process of polylactone polyols and continuously expose and renew the polydimethylsiloxane segments on the coating surface, thereby ensuring the coating's persistent low surface energy, self-repairing ability, and long-term durability.

[0081] In summary, the present application successfully prepares a block copolymer with a specific structure as the core film-forming resin by chain extension polymerization of polycaprolactone diol, polycaprolactone tetrol, and polydimethylsiloxane diol. The introduction of polycaprolactone tetrol forms a key cross-linked network, providing the coating with structural stability and solvent resistance; polydimethylsiloxane diol endows the coating with low surface energy characteristics; and the block structure formed by chain extension polymerization ensures that the self-polishing degradation of the polylactone portion can effectively renew the surface polydimethylsiloxane segments. These three components and the specific polymerization process produce significant synergistic effects: the combination of chemical self-polishing and physical self-repairing, as well as the structural stability provided by the cross-linked network, collectively significantly improve the long-term durability and corrosion resistance of the coating in marine environments, achieving excellent antifouling effects.

[0082] Experimental Example 2

[0083] The short-term and long-term bio-inhibition rates and biocide release rates of the antifouling coatings prepared in Examples 7-12 and Comparative Examples 4-6 were tested in marine environment, and the relevant results are summarized in Table 4.

[0084] The test method for short-term and long-term bio-inhibition rates was as follows: the experimental method of GBT 5370-2007 standard was referred to, and the antifouling scores of the coating samples after three months and one year were recorded according to the scoring standard of 7.2 antifouling property evaluation in the standard.

[0085] The test method for biocide release rate was as follows: a 150 mm x 75 mm coating sample was soaked in V = 50 L artificial seawater, and the concentration C t (µg / L) of butenolide in the artificial seawater was determined after one month of soaking at 25°C, and the average biocide release rate R t = (C t x V) / (A x Δt) was calculated, where A was the test area of the coating, and Δt was the sampling interval time (days).

[0086] Table 4 Bio-inhibition rates and biocide release rates of the coatings prepared in Examples 7-12 and Comparative Examples 4-6

[0087]

[0088] As shown in the data in Table 4, the antifouling scores of the antifouling coating prepared in Example 7 after three months and one year were both excellent, reaching 95 points and 92 points, respectively, and the average biocide release rate thereof was maintained at a low level of 1.55 µg / cm 2 / day, which indicated that it had high and persistent antifouling performance and good biocide release control ability.

[0089] Compared with Example 7, Comparative Example 4 did not undergo the self-assembly crosslinking process, but directly used the antifouling microcapsules without the construction of multi-layer shells to replace the responsive microcapsules. The antifouling score thereof after three months was only 74 points, which was much lower than that of Example 7, and the biocide release rate was as high as 5.26 µg / cm 2 / day. This indicates that the response microcapsule with a multi-layer shell and environmental responsiveness prepared by the emulsification solidification and self-assembly cross-linking process is crucial for achieving efficient use and phased release of biocides. The lack of a multi-layer shell constructed by self-assembly cross-linking cannot effectively regulate the release of butenolide, and also lacks the N-acylated L-homoserine lactone layer that inhibits biofilm formation in the early stage, resulting in poor early antifouling effect and rapid loss of biocides. Comparative Example 5 does not add N-acylated L-homoserine lactone in the self-assembly cross-linking process. Its antifouling score is 75 after three months, and the score drops to 69 after one year. N-acylated L-homoserine lactone is a key component in the shell layer of the response microcapsule for inhibiting biofilm formation in the early stage. The lack of this component makes it difficult for the coating to prevent the attachment signal of large-scale fouling organisms from the root in the early stage of 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 weaker. This highlights the key role of N-acylated L-homoserine lactone in achieving phased and cascading release of the antifouling mechanism. Comparative Example 6 does not add response microcapsules, but disperses an equal amount of butenolide directly into the coating. Although its antifouling score reaches 85 after three months, it drops to 65 after one year, and the biocide release rate soars to 15.39 µg / cm 2 / day. This indicates that the lack of encapsulation and responsive release mechanism of microcapsules causes butenolide biocides to be rapidly and massively dissolved, not only resulting in huge waste and reducing the utilization efficiency of antifouling agents, but also failing to provide long-term antifouling protection and posing greater chemical emission risk to the environment.

[0090] In summary, the present application prepares antifouling microcapsules by emulsification solidification of butenolide and polycaprolactone diol, and then constructs a multi-layer shell by self-assembly cross-linking of chitosan, sodium alginate, and N-acylated L-homoserine lactone. This special microcapsule additive and its components synergistically work in the marine environment. After the coating contacts seawater, N-acylated L-homoserine lactone in the shell layer first plays a role in effectively inhibiting the formation of early biofilms, and then the microcapsule slowly and continuously releases the core butenolide biocide to consolidate the antifouling effect. This on-demand, phased, and cascading release mechanism significantly improves the utilization efficiency of antifouling agents and the long-term antifouling performance of the coating, while minimizing chemical emissions to the marine environment.

[0091] Experimental Example 3

[0092] The durability and corrosion resistance of the antifouling coatings prepared in Examples 13-16 and Comparative Examples 7-9 in the marine environment were tested, and the related results are summarized in Table 5.

[0093] The test method for coating durability and coating corrosion resistance refers to Experimental Example 1.

[0094] Table 5 Coating corrosion resistance and durability of the coatings prepared in Examples 13-16 and Comparative Examples 7-9

[0095]

[0096] As shown in the data of Table 5, the antifouling coating prepared in Example 13 exhibits excellent performance in initial abrasion index, abrasion index after 30 days of immersion, abrasion index after 180 days of immersion, and coating resistance performance retention rate after 180 days, fully demonstrating its excellent durability and corrosion resistance in marine environment. Compared with Example 13, Comparative Example 7 does not add functional fillers. Its coating performance is overall significantly reduced, the abrasion index I2 after 180 days is significantly increased relative to Example 1, and the performance retention rate is also dramatically reduced from 93.4% to 78.3%. This indicates that the introduction of functional fillers has a decisive impact on the durability and corrosion resistance of the coating. Without the electrochemical corrosion inhibition effect of zinc phosphate and the physical shielding effect of mica iron oxide, the overall protective ability of the coating is significantly insufficient. Comparative Example 8 changes the phase separation curing process, only a single-stage curing at 25°C is performed, while Example 13 adopts a three-stage specific drying and curing process. The abrasion index I2 after 180 days and the performance retention rate of Comparative Example 8 are both inferior to those of Example 13. This shows that the specific phase separation curing process is crucial for inducing ideal micro-phase separation on the surface and inside of the coating. This micro-phase separation can form a low-surface-energy interface in situ on the surface of the coating, reducing the initial adhesion of fouling organisms, and at the same time optimizing the overall structure of the coating, thereby synergistically improving the durability and corrosion resistance of the coating. Comparative Example 9 only adds mica iron oxide in the functional fillers, without adding zinc phosphate. Although its initial and long-term abrasion indices are similar to those of Example 13, the performance retention rate is significantly reduced from 93.4% of Example 13 to 82.7%. The key role of zinc phosphate is to form a dense phosphate complex film on the interface between the coating interior and the ship body substrate, effectively inhibiting the electrochemical process of corrosion. Without zinc phosphate, even if the physical shielding effect of mica 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.

[0097] In summary, the application realizes synergistic effect through specific block copolymer, functional filler in composite additives and specific phase separation curing process. The reticular crosslinking system formed by the block copolymer ensures good structural stability of the coating. The specific phase separation curing process induces the formation of low surface energy interface on the surface of the coating, reducing the attachment of fouling organisms. Zinc phosphate forms a phosphate complex film at the interface of the substrate, providing electrochemical corrosion protection; at the same time, the unique flaky structure of iron oxide mica forms an overlapping physical barrier in the coating, prolonging the penetration path of the corrosion medium. These technical means and material interactions in-situ build a multi-level protective system on the surface of the ship body substrate, ensuring the basic strength of the coating while significantly improving its durability and corrosion resistance in the marine environment.

[0098] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are only by way of example and that modifications, changes, substitutions and alterations can be made thereto without departing from the spirit and scope of the application as set forth in the following 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; The polycaprolactone polyol comprises: polycaprolactone diol and polycaprolactone tetraol; 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 and 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 rotary distilling to remove the residual solvent to obtain the block copolymer; Butenolide and polycaprolactone diol are emulsified and solidified to obtain antifouling microcapsules; 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 ultrasound assistance, stirring and volatilizing the mixture, centrifuging to obtain a product, and washing with deionized water to obtain the antifouling microcapsules; cross-linking the antifouling microcapsules through self-assembly to obtain responsive microcapsules; The self-assembly cross-linking process comprises: alternately positively charging and negatively charging the antifouling microcapsules, performing the two processes alternately and for equal times, adding the treated reaction product dropwise into a calcium chloride aqueous solution, centrifuging and discarding the supernatant to obtain the responsive microcapsules; The positive charge conversion process comprises: dissolving chitosan in an acetic acid solution to prepare a chitosan solution; mixing the antifouling microcapsules with the chitosan solution, stirring, centrifuging, discarding the supernatant, and washing; The negative charge treatment process comprises: dissolving sodium alginate and N-acylated L-homoserine lactone in deionized water to prepare a negative charge solution; dispersing the positively charged antifouling microcapsules in deionized water, and then adding the positively charged antifouling microcapsules to the negative charge solution and stirring. 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; solidifying the antifouling paint through phase separation to obtain an antifouling coating; 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.

2. 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.

3. 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 2; the antifouling paint for ships comprises: block copolymers, responsive microcapsules, dispersing aids, compounded solvents and functional fillers.

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