Surface self-generating hydrogel marine antifouling paint with double cross-linked network

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a surface self-generating hydrogel marine antifouling coating with a double cross-linked network. The marine antifouling paint comprises a component A and a component B, the component A is composed of 50-75 parts of acrylic resin, 25-50 parts of a solvent and 0-5 parts of an auxiliary agent, the component B is composed of 5-25 parts of an alkaline silane coupling agent, 10-25 parts of polyethyleneimine and 50-85 parts of a solvent, and the mass ratio of the component A to the component B is 100: (20-60). The coating has a silicon-oxygen bond and imine bond dual cross-linked network, so that a microgel surface with high hydration degree, controllable swelling degree and self-updating capability is generated in situ in a coating in a service environment, and an excellent and stable marine antifouling function can be realized without an additional antifouling agent. The coating is low in cost and stable in antifouling property, and can be used as antifouling coatings and antibacterial coatings in various occasions such as ships, pipelines, marine industrial facilities, marine aquaculture facilities and the like in a seawater environment.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, and specifically relates to a marine antifouling coating. Background Technology

[0002] Marine fouling organisms can increase ship drag and facility maintenance costs, becoming a key issue hindering the development of marine industries. With the ban on traditional organotin self-polishing antifouling coatings worldwide in 2008, the development of marine antifouling coatings that combine environmental friendliness with durable antifouling capabilities is an urgent need in the field of marine antifouling.

[0003] Inspired by the mucus on the skin of frogs and fish, hydrogels have been widely used in marine antifouling coatings. This is because hydrogels possess a highly hydrophilic polymer network that can form a hydration layer on the coating surface, effectively inhibiting the adhesion of fouling substances. Furthermore, hydrogels can be combined with antifouling agents and antibacterial groups to exert a biomimetic synergistic antifouling effect, further enhancing antifouling performance. However, hydrogels inevitably suffer from problems such as excessively high swelling ratios, poor mechanical properties, and easy peeling after absorbing water, making it difficult to achieve a durable antifouling effect in actual marine environments.

[0004] Existing hydrogel marine antifouling coatings generally employ multi-component or multi-layer composite strategies to improve the long-lasting antifouling capability of hydrogels. Chinese invention patent CN 119081546 A combines hydroxyl-containing silicone resin with silicone gel and antifouling agents to prepare an organic-inorganic composite antifouling coating. This coating forms a microporous hydrogel layer during use and slowly releases the antifouling agent, exhibiting a long effective service life. Chinese invention patent CN 118725729 A reports a composite hydrogel marine antifouling coating composed of a Kevlar hydrogel adhesion layer and a copper-ion-containing polycaffeic acid hydrogel layer. Due to the good mechanical properties and acid and alkali resistance of Kevlar hydrogel, the coating simultaneously possesses high hydrophilicity and good durability. While these strategies improve the actual service performance of hydrogels, challenges remain regarding component compatibility and ease of preparation.

[0005] Chinese invention patent CN 118324978 A, based on self-polishing antifouling resin of acrylic metal salts, introduces hydrophilic structural units such as hydroxyl, amino, and carboxyl groups, and adds a crosslinking agent to form a three-dimensional network structure of the resin molecular chains. During immersion, the hydrophilic groups absorb water under the constraint of the three-dimensional network, thereby forming a hydrogel layer on the coating surface. This self-generated hydrogel layer can effectively inhibit the adhesion of biofouling and also improve the coating's long-lasting antifouling ability. However, the structure of the crosslinking network simultaneously affects the swelling degree of the hydrogel and the self-polishing rate of the coating. Relying on a single crosslinking network is insufficient to simultaneously achieve high water resistance, high hydration degree, and controllable self-polishing. Therefore, there is a need to develop a surface-generating hydrogel marine antifouling coating with a dual crosslinking network to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to address the limitations of existing technologies by providing a long-lasting, stable, self-polishing marine antifouling coating with a dual cross-linked network that can generate surface hydrogels in situ.

[0007] The present invention provides a surface-self-generating hydrogel marine antifouling coating with a dual cross-linked network, comprising component A and component B, wherein component A, by mass parts, has the following composition:

[0008] Acrylic resin: 50-75;

[0009] Solvent: 25-50;

[0010] Additives: 0-5%; preferably 1-5%.

[0011] Component B, by mass, has the following composition:

[0012] Basic silane coupling agent: 5-25;

[0013] Polyethyleneimine: 10-25;

[0014] Solvent: 50-85;

[0015] The mass ratio of component A to component B is 100:20 to 60.

[0016] The acrylic resin has the following molecular structural formula (1):

[0017]

[0018] In Formula 1, I and I* represent the initiator composition structure. M1, M2, M3, M4, and M5 can all be independently selected from H or CH3. R1, R2, R4, and R5 can be selected from C1 to C6 alkyl groups. R3 can be selected from CH3 or CH2CH3. X can be selected from H, CH3, OCH3, or OCH2CH3. The subscripts a, b, c, d, and e in square brackets represent the amount of monomers used in the brackets. The mass percentage of the five monomers a, b, c, d, and e is 15–25:20–50:5–25:5–25:5–25, totaling 100%. The number average molecular weight of the resin is controlled between 1000 and 100000 g / mol.

[0019] The alkaline silane coupling agent is selected from 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, diethylenetriaminepropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, diethylenetriaminepropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3 -Anilinepropyltrimethoxysilane, bis-[3-(trimethoxysilane)-propyl]-amine, N-n-butyl-3-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, tetramethylguanidinopropyltrimethoxysilane, N-(trimethoxysilylpropyl)imidazolium; the above silane coupling agents participate in the crosslinking and curing of the resin matrix and provide basic groups for the hydrolytic polishing of the coating.

[0020] The polyethyleneimine curing agent is a branched polyethyleneimine with a molecular weight range of 300–1800 g / mol; the above-mentioned polyethyleneimine curing agent participates in the cross-linking and curing of the resin matrix and provides hydrophilic segments for the formation of hydrogel on the coating surface.

[0021] The solvent is selected from one or more combinations of amyl acetate, butyl acetate, ethyl acetate, ethanol, isopropanol, n-butanol, toluene, xylene, acetone, methyl isobutyl ketone, cyclohexanone, ethylene glycol dibutyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate.

[0022] The additives include leveling agents, wetting agents, and defoamers for coatings, which are mainly used to adjust the appearance of the coating film and can be added or not depending on the actual situation.

[0023] The present invention also provides a method for preparing the above-mentioned marine antifouling coating, the specific process of which is as follows:

[0024] First, acrylic resin was prepared using solution polymerization. Specifically, a certain amount of butyl acetate was added to a four-necked flask as the bottom solution for resin synthesis, and the temperature was initially raised to reflux temperature. Then, monomers such as isobornyl methacrylate, methyl methacrylate, butyl acrylate, γ-methacryloyloxypropyltrimethoxysilane, triisopropylsilyl methacrylate, and ethylene glycol acetoacetate methacrylate were mixed in proportion, and an initiator was added. After stirring until homogeneous, a monomer mixture was obtained. After the bottom solution began to boil and reflux, the monomer mixture was added dropwise over 3-4 hours. After the addition was complete, the reaction continued for 1 hour, then the temperature was raised by 5°C, and the reaction was continued for 0.5 hours. Finally, the mixture was cooled to room temperature to obtain the acrylic resin.

[0025] Then, the acrylic resin, solvent, and additives are stirred and mixed evenly in proportion to obtain coating component A; the alkaline silane coupling agent, polyethyleneimine, and solvent are mixed evenly to obtain component B; before use, components A and B are mixed in proportion to obtain the desired coating.

[0026] like Figure 1 As shown, in the coating composition of this invention, the alkaline silane coupling agent catalyzes the formation of a siloxane bond (Si-O-Si) crosslinking network from the silanoxy groups in the resin, while polyethyleneimine can form an imine bond (-C=N-) crosslinking network with the β-dicarbonyl structure in the resin. This allows for curing at room temperature to obtain a coating film with a dual crosslinking network. During seawater immersion, the silanol ester groups in the acrylic resin hydrolyze while the amino groups in the polyethyleneimine chain protonate, increasing the hydrophilicity of the coating surface and forming a hydration layer. The silane coupling agent and polyethyleneimine introduce a large number of alkaline groups into the crosslinking network, resulting in a highly alkaline hydration layer on the coating surface, which promotes the hydrolysis of the crosslinking network and enables surface self-renewal. The dual crosslinking network functions as follows: the imine bond crosslinking network has strong hydrophilicity, rapid hydrolysis, and easy swelling, allowing for rapid hydration of the coating surface and achieving underwater superoleophobicity; the siloxane bond crosslinking network has weak hydrophilicity, slow hydrolysis, and lower swelling degree, allowing for control of water absorption, swelling, and hydrolysis processes on the coating surface. Therefore, after immersion in seawater, the coating can generate a surface microgel in situ with high hydration, controllable swelling, and self-polishing capabilities. In the marine environment, the coating relies on the gel hydration layer to block the adhesion of fouling organisms, relies on the surface alkaline microenvironment, polycations, and intrinsic antibacterial groups to kill fouling organisms, and relies on its self-polishing ability to release fouling and renew the surface. Ultimately, the coating can achieve excellent and stable marine antifouling performance without the need for external antifouling agents.

[0027] The surface microgels formed by the above-mentioned coatings mainly possess three characteristics: structural durability, underwater superoleophobicity, and high-efficiency antifouling. The underwater superoleophobicity of the surface microgels was characterized by the underwater oil contact angle of hexadecane after immersion in the coating. Specifically, the oil contact angle was first measured when the cured coating was placed directly underwater. Then, the coating was placed in artificial seawater and statically immersed for 3 days, and its underwater oil contact angle was measured again. Additionally, the coating was placed in a mechanical propulsion device and dynamically immersed at a speed simulating 10 knots for 3 days, and its underwater oil contact angle was measured again. These data reflect the rapid hydration capability of the coating surface and the oleophobicity of the hydrated layer after hydrolysis under different conditions. The structural durability of the surface microgels is mainly reflected by the changes in the macroscopic and microscopic morphology of the coating surface during the immersion process. Specifically, the coating was placed in artificial seawater and immersed for 3 days and 30 days respectively. After removal, the coating was first observed for whitening, peeling, or flaking. Then, the coating was freeze-dried and its surface morphology was observed using a scanning electron microscope. The water absorption rate and weight loss rate of the coating after immersion were measured to evaluate the swelling resistance and self-polishing ability of the surface microgel. The high antifouling efficiency of the surface microgel was characterized by laboratory antibacterial and antifouling tests. Specifically, the laboratory antibacterial test of the coating involved inoculating the coating and glass slide surfaces with bacterial suspensions of Escherichia coli and Shewanella loihica, respectively, and culturing for one day. The ratio of the number of viable bacteria recovered from the coating surface to the number of viable bacteria recovered from the blank glass slide surface was used to reflect the antibacterial rate of the coating. The laboratory antifouling test of the coating involved immersing the coating in a fluorescently labeled bovine serum albumin (FITC-BSA) solution and a suspension of Chlorella sp. for one day, respectively, and then observing the protein and microalgae adhesion on the coating surface using a laser confocal microscope in fluorescence mode.

[0028] This invention relates to a surface-generating hydrogel marine antifouling coating with a dual cross-linked network. On the one hand, it possesses the excellent resistance-reducing adhesion properties of hydrogel antifouling coatings; on the other hand, it significantly improves upon the shortcomings of existing hydrogel antifouling coatings in terms of antifouling durability. Furthermore, it combines the continuous fouling-killing and surface self-renewal capabilities of self-polishing antifouling coatings to further enhance its practical service performance. This coating is low-cost, environmentally friendly, and easy to prepare. It is suitable for antifouling coatings in various applications in seawater environments, including ships, pipelines, marine industrial facilities, and aquaculture facilities. It can also be used as an antibacterial coating. Attached Figure Description

[0029] Figure 1 The images show the surface morphology of the coatings in Comparative Examples 1-3 and Examples 1-4 after being immersed in artificial seawater for 3 days.

[0030] Figure 2The images show the surface morphology of the coatings in Comparative Examples 1-3 and Examples 1-4 after being immersed in artificial seawater for 30 days.

[0031] Figure 3 This is a SEM image of the cross-sectional morphology of the coating in Example 3 after immersion in artificial seawater for 30 days. Detailed Implementation

[0032] The present invention will be further described below through specific embodiments and comparative examples.

[0033] I. Preparation of acrylic resin matrix

[0034] Isoborneol methacrylate was selected as monomer a, a mixture of methyl methacrylate and butyl acrylate as monomer b, γ-methacryloyloxypropyltrimethoxysilane as monomer c, triisopropylsilyl methacrylate as monomer d, and ethylene glycol acetoacetate methacrylate as monomer e. Mixtures of the above monomers and initiator in different proportions were dissolved in a certain amount of butyl acetate solvent, and the mixture was heated to initiate the synthesis of the acrylic resin of the example. Alternatively, monomers c, d, and e were removed from the formulation, and the mixture of the remaining monomers and initiator was dissolved in a certain amount of butyl acetate solvent, and the mixture was heated to initiate the synthesis of the acrylic resin of the comparative example. The resin synthesis formulations of the examples and the comparative example are shown in Table 1.

[0035] Table 1 Synthesis of acrylic resins

[0036]

[0037] II. Preparation of surface-self-generating hydrogel marine antifouling coatings with dual cross-linked networks

[0038] The acrylic resin in Table 1 was mixed with appropriate amounts of solvent and additives to obtain coating component A for the examples and control examples, as shown in Table 2; Component B was prepared by mixing alkaline silane coupling agent, polyethyleneimine, and solvent, as shown in Table 3. Component A from Table 2 and the corresponding component B from Table 3 were then mixed at a mass ratio of 2:1 and stirred at room temperature for 10 minutes to obtain a uniform coating. The coating was applied to a glass substrate and cured at room temperature for 3 days, resulting in a coating film thickness of 30 ± 5 μm.

[0039] Table 2. Proportions of Component A

[0040]

[0041]

[0042] Table 3. Proportions of Component B

[0043]

[0044]

[0045] III. Characterization and Comparison of Various Coating Properties

[0046] After immersion in artificial seawater for 3 days: Control Example 1 coating turned severely white, with pits caused by hydrolysis and dissolution on the surface; Control Example 2 coating turned white, with a clear porous gel structure on the surface; Control Example 3 coating surface was smooth without peeling or flaking, and had a clear porous gel structure; Examples 1, 3, 5, 7, and 9 coating surfaces were smooth without peeling or flaking, and had a clear porous gel structure; Examples 2, 4, 6, and 8 coatings showed some degree of whitening, and had a clear porous gel structure on the surface. The surface structures of the coatings in Control Examples 1-3 and some examples are shown below. Figure 1 .

[0047] After immersion in artificial seawater for 30 days: the coating of Control Example 1 showed no significant change in appearance compared to 3 days prior, with the surface still predominantly exhibiting a pitted structure. The water absorption rate of the coating was 17.8%, and the weight loss was 1.09 mg / cm³. 2 In control example 2, the coating exhibited peeling, with increased swelling of the surface gel structure. The coating's water absorption rate was 35.3%, and its weight loss was 1.36 mg / cm³. 2 In contrast, the swelling degree of the gel structure on the coating surface of control example 3 was reduced, the water absorption rate of the coating film was 18.9%, and the weight loss rate was 0.39 mg / cm³. 2 Example 1: The coating appearance showed no significant change compared to 3 days later; the surface largely maintained its original porous gel structure. The coating's water absorption rate was 21.7%, and its weight loss rate was 0.78 mg / cm³. 2 Example 2: The coating exhibited a certain degree of peeling, but the surface basically maintained its original porous gel structure. The water absorption rate of the coating was 26.8%, and the weight loss rate was 0.64 mg / cm³. 2 Example 3: The coating appearance showed no significant change compared to 3 days later; the surface still largely maintained its original porous gel structure. The coating's water absorption rate was 22.6%, and its weight loss rate was 0.68 mg / cm³. 2 In Example 4, a certain degree of peeling was observed in the coating. The surface basically maintained its original porous gel structure. The water absorption rate of the coating was 27.9%, and the weight loss rate was 0.71 mg / cm³. 2 Example 5: The coating appearance showed no significant change compared to 3 days later; the surface largely maintained its original porous gel structure. The coating's water absorption rate was 24.9%, and its weight loss rate was 0.45 mg / cm³. 2 Example 6: The coating appearance showed no significant change compared to 3 days later; the surface still largely maintained its original porous gel structure. The coating's water absorption rate was 27.3%, and its weight loss rate was 0.51 mg / cm³. 2Example 7: The coating appearance showed no significant change compared to 3 days later; the surface still largely maintained its original porous gel structure. The coating's water absorption rate was 24.5%, and its weight loss rate was 0.69 mg / cm³. 2 Example 8: The coating appearance showed no significant change compared to 3 days later; the surface still largely maintained its original porous gel structure. The coating's water absorption rate was 27.8%, and its weight loss rate was 0.98 mg / cm³. 2 Example 9: The coating appearance showed no significant change compared to 3 days later; the surface still largely maintained its original porous gel structure. The coating's water absorption rate was 19.9%, and its weight loss rate was 0.61 mg / cm³. 2 The coating surface structures of Comparative Examples 1-3 and some embodiments are shown below. Figure 2 .

[0048] The underwater oleophobic and antifouling properties of each coating are shown in Table 4. The initial underwater oil contact angle refers to the oil contact angle when the cured coating is placed directly underwater, while the dynamic and static underwater oil contact angles refer to the oil contact angles after dynamic and static immersion, respectively. Antibacterial rate = (number of viable bacteria recovered from the blank glass slide surface - number of viable bacteria recovered from the coating surface) / (number of viable bacteria recovered from the blank glass slide surface). A value of 100% indicates no viable bacteria recovery. Antifouling rate = (number or area of ​​contamination on the blank glass slide surface - number or area of ​​contamination on the coating surface) / (number or area of ​​contamination on the blank glass slide surface). A positive value indicates that the contamination on the coating surface is less than that on the blank glass slide surface, while a negative value indicates that the contamination on the coating surface is more than that on the blank glass slide surface.

[0049] Table 4. Underwater oleophobic and antifouling properties of the coating.

[0050]

[0051] As can be seen from the table above, Control Example 1, due to the inability to form an imine bond cross-linking network, resulted in poor compatibility between the basic silane coupling agent and the resin matrix. During immersion, the hydrophilic phase dissolved rapidly, failing to form a surface gel layer, and exhibiting weak anti-protein and anti-microalgae adhesion capabilities. Control Example 2, lacking a siloxane bond cross-linking network, struggled to effectively inhibit water absorption and swelling, leading to poor gel layer durability. Control Example 3, lacking hydrolyzable hydrophilic groups, had a low underwater oil contact angle, resulting in weak anti-protein and anti-microalgae adhesion capabilities. The results of the above embodiments demonstrate that the coating composition described in this invention can effectively form a surface microgel, while simultaneously achieving underwater superoleophobicity, structural durability, and high-efficiency antifouling properties. This allows the coating to achieve excellent and stable antibacterial and marine antifouling capabilities without the need for external antifouling agents.

[0052] The embodiments described above are for further illustrating the technical content of the present invention and are not intended to limit the scope of the present invention. Any modifications or technical extensions made based on the present invention without departing from the principle of the present invention shall be considered within the scope of protection of the present invention.

Claims

1. A surface-self-generating hydrogel marine antifouling coating with a dual cross-linked network, characterized in that, It consists of component A and component B, wherein: Component A, by mass, has the following composition: Acrylic resin: 50-75; Solvent: 25-50; Additives: 0-5; Component B, by mass, has the following composition: Basic silane coupling agent: 5-25; Polyethyleneimine: 10-25; Solvent: 50-85; The mass ratio of component A to component B is 100:20 to 60.

2. The marine antifouling coating according to claim 1, characterized in that, The acrylic resin has the following general structural formula: Wherein, I and I* are the initiator composition structures, M1, M2, M3, M4, and M5 are independently selected from H or CH3, R1, R2, R4, and R5 are C1-C6 alkyl groups, R3 is CH3 or CH2CH3, and X is H, CH3, OCH3, or OCH2CH3.

3. The marine antifouling coating according to claim 1, characterized in that, In the acrylic resin, the five monomers a, b, c, d, and e are present in a mass percentage ratio of 15–25:20–50:5–25:5–25:5–25, totaling 100%; and the number average molecular weight of the acrylic resin is 1,000–100,000.

4. The marine antifouling coating according to claim 1, characterized in that, The alkaline silane coupling agent is selected from 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, diethylenetriaminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-anilinepropyltrimethoxysilane, bis-[3-(trimethoxysilyl)-propyl]-amine, N-n-butyl-3-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, tetramethylguanidinopropyltrimethoxysilane, and N-(trimethoxysilylpropyl)imidazolium.

5. The marine antifouling coating according to claim 1, characterized in that, The polyethyleneimine curing agent is branched polyethyleneimine with a molecular weight of 300–1800 g / mol.

6. The marine antifouling coating according to claim 1, characterized in that, The solvent is selected from amyl acetate, butyl acetate, ethyl acetate, ethanol, isopropanol, n-butanol, toluene, xylene, acetone, methyl isobutyl ketone, cyclohexanone, ethylene glycol dibutyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate.

7. The method for preparing the marine antifouling coating according to any one of claims 1-6, characterized in that, The specific process is as follows: First, acrylic resin is synthesized by solution polymerization. Then, the acrylic resin, solvent, and additives are stirred and mixed evenly in proportion to obtain coating component A. The basic silane coupling agent, polyethyleneimine, and solvent are mixed evenly to obtain component B. Before use, components A and B are mixed in proportion to obtain the desired coating.

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