Intrinsically alkaline, self-polishing, underwater superoleophobic marine antifouling coating and its preparation method

Abstract

This invention belongs to the field of fine chemical technology, specifically an intrinsically alkaline, self-polishing, underwater superoleophobic marine antifouling coating and its preparation method. The marine antifouling coating of this invention comprises: 40-80 parts acrylic resin, 2-20 parts aminosiloxane, 0.5-7.5 parts aliphatic tertiary amine, 20-45 parts solvent, and 0-5 parts additives. This coating achieves multiple antifouling effects, including intrinsic surface alkalinity, underwater superoleophobicity, and biomimetic micro / nano structure, without the need for external antifouling agents, relying on the spontaneous microphase separation of aminosiloxane in the resin matrix. This coating is low in cost, environmentally friendly, and has stable antifouling performance, making it suitable for antifouling coatings in various applications such as ships, pipelines, marine industrial facilities, and aquaculture facilities in seawater environments. It can also be used as an antibacterial coating.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a marine antifouling coating material and its preparation method. Background Technology

[0002] Marine antifouling coatings are materials that prevent the adhesion of organic pollutants and inhibit the growth of marine microorganisms on surfaces, making them crucial for the maintenance of marine facilities and the navigation of ships. Common marine antifouling coatings can be broadly classified into two categories: self-polishing antifouling coatings and fouling-release antifouling coatings. Self-polishing antifouling coatings form a hydrophilic surface through the hydrolysis of specific groups in the resin, ultimately achieving self-polishing under the scouring of seawater. Furthermore, they are often combined with antifouling agents, utilizing the self-polishing properties of the coating surface to ensure the continuous release of the antifouling agent, thereby maintaining a high concentration of biocides on the coating surface. Therefore, self-polishing antifouling coatings exhibit excellent and stable antifouling effects in actual marine environments. However, traditional organotin self-polishing antifouling coatings were banned worldwide in 2008 due to their harmful effects on the marine environment. Therefore, developing new environmentally friendly self-polishing antifouling coatings is currently an important issue in the field of marine antifouling.

[0003] The main research directions of existing environmentally friendly self-polishing antifouling coatings include: (1) using natural or artificially synthesized non-toxic antifouling agents; (2) introducing hydrophilic components such as hydrogels and zwitterions to form a hydration layer on the coating surface that inhibits the adhesion of pollutants, thereby reducing the need for antifouling agents in the coating. Related reports include: Chinese invention patent CN201811652868.4 introduces structures such as isoborneol and methyl nicotinamide pyridinium salt into the polymer molecular chain through copolymerization, and prepares a linear self-polishing antifouling resin rich in biocides. Chinese invention patent CN114907740A combines a main resin with self-polishing ability with an auxiliary resin that can migrate to the coating surface to form a hydrogel layer, which enhances the antifouling ability of the resin itself, thereby significantly reducing the amount of antifouling agent added in the coating. Although the above antifouling coatings have improved in terms of environmental friendliness, the introduction of antifouling agents is still essential because the resin matrix itself lacks the inhibitory effect on the growth of pollutants. However, traditional copper-containing antifouling agents still have cumulative biotoxic effects; biocides are environmentally friendly, but costly and have less than ideal durability. This makes it difficult for existing environmentally friendly self-polishing antifouling coatings to simultaneously achieve high environmental friendliness, low cost, and long-term practicality.

[0004] Chinese invention patent CN1218820A reports a non-toxic marine antifouling coating based on basic silicate antifouling agents. Unlike antifouling coatings containing traditional antibacterial agents, this coating relies on the dissolution of basic silicates to form a strongly alkaline ionic layer on its surface, thereby inhibiting the growth of bacteria and marine organisms without causing any pollution to the marine environment. Although basic silicates are a low-cost, environmentally friendly, and non-toxic antifouling agent, they need to be introduced into the resin matrix in high quantities, which can cause the resin matrix to degrade rapidly, resulting in a short effective period. Therefore, it is necessary to develop an intrinsically high-alkaline, non-toxic, self-polishing antifouling coating that does not rely on the addition of silicates or other antifouling agents. Summary of the Invention

[0005] The purpose of this invention is to address the limitations of existing technologies by providing an intrinsically alkaline, non-toxic, self-polishing, underwater superoleophobic marine antifouling coating and its preparation method. This environmentally friendly and highly efficient self-polishing marine antifouling coating combines the antifouling properties of a highly alkaline surface with underwater superoleophobic properties, without relying on external antifouling agents.

[0006] The intrinsically alkaline, self-polishing, underwater superoleophobic marine antifouling coating provided by this invention has the following specific components by weight:

[0007] Acrylic resin: 40-80;

[0008] Aminosiloxane: 2-20;

[0009] Aliphatic tertiary amines: 0.5-7.5;

[0010] Solvent: 20-45;

[0011] Additives: 0-5; Preferred additives: 1-5.

[0012] The acrylic resin has the following general structural formula:

[0013]

[0014] Among them, I and I* are the initiator composition structures, M1, M2, and M3 can be independently selected from H or CH3, R1, R2, and R4 can be selected from C1-C6 alkyl groups, R3 can be selected from CH3 or CH2CH3, and X can be selected from H, CH3, OCH3, or OCH2CH3; the mass ratio of the four monomers a, b, c, and d is (15-25):(30-60):(5-25):(5-25), totaling 100%; the number average molecular weight of the resin is controlled between 5000 and 100000.

[0015] The aminosiloxane has the following general structural formula:

[0016]

[0017] Among them, R3 can be CH3 or CH2CH3, X can be H, CH3, OCH3 or OCH2CH3; n is an integer, and its value ranges from 2 to 5.

[0018] The aliphatic tertiary amine is selected from one or more combinations of trimethylamine, triethylamine, N,N-dimethylethylamine, and N,N-diethylmethylamine; the above aliphatic tertiary amine can adjust the polarity of the solvent system and form hydrogen bonds with the aminosiloxane in the coating, thereby inducing phase separation.

[0019] 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.

[0020] 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.

[0021] This invention also provides a method for preparing the above-mentioned intrinsically alkaline self-polishing underwater superoleophobic marine antifouling coating, the specific steps of which are as follows:

[0022] First, acrylic resin is synthesized by solution polymerization. After obtaining the moisture-curing acrylic resin, aminosiloxane curing agent, aliphatic tertiary amine, solvent and additives are added in sequence according to the formula. The mixture is stirred and dispersed for 10-30 minutes to obtain the desired coating.

[0023] In the coating composition of this invention, aminosiloxane acts as a catalyst and curing agent, promoting the moisture curing of the acrylic resin matrix into a film at room temperature, such as... Figure 1 As shown; in this process, due to the hydrogen bonding between amino groups and the polarity difference between amino groups and resin molecular chains, aminosiloxanes aggregate and separate into microphases, resulting in a cured coating film that simultaneously possesses a hydrophilic dispersed phase enriched with aminosiloxanes and a continuous resin phase enriched with polymer molecular chains. During seawater immersion, due to the hydrophilicity and alkalinity of aminosiloxanes, the hydrophilic dispersed phase on the coating surface dissolves rapidly, forming a highly alkaline hydration layer on the coating surface that is unfavorable to the growth of fouling organisms, thus achieving intrinsic alkaline antifouling. Meanwhile, the continuous resin phase gradually transforms from hydrophobic to hydrophilic through the hydrolysis of organosilicon esters, causing the molecular chains to peel off from the surface under the action of seawater, thereby achieving underwater superoleophobicity of the coating surface and controllable self-polishing ability. Due to the difference in dissolution rates between the dispersed and continuous phases on the coating surface, the above process also forms an ordered biomimetic micro / nano structure on the coating surface (such as... Figure 2This further enhances the underwater superoleophobic properties of the coating surface. The combination of these properties enables the coating to possess excellent and stable antifouling performance without the need for external antifouling agents.

[0024] The surface alkalinity of the above coating under seawater immersion was reflected by the color change of phenolphthalein indicator. Specifically, 1 mL of artificial seawater containing phenolphthalein indicator was dropped onto the cured coating surface, left to stand for 10 minutes, and the color development of the indicator in the droplet was observed. Since phenolphthalein indicator changes from colorless to purple-red within the pH range of 8-10, the color development of the indicator can directly prove that a highly alkaline hydration layer has formed on the coating surface. The underwater oleophobic properties of the above coating were characterized by alternating immersion tests in artificial seawater. Specifically, the cured coating was placed in artificial seawater and kept statically immersed for 3 days, and its underwater oil contact angle was measured using n-hexadecane; then the coating was placed in a mechanical propulsion device and dynamically immersed at a speed of 10 knots for 15 days, and its underwater oil contact angle was measured again; finally, the coating was placed back into artificial seawater for static immersion for 3 days, and the recovery of its underwater oil contact angle was measured. The laboratory antibacterial test of the above coating involved inoculating the coating and glass slide surfaces with bacterial suspensions of *E. coli* and *S. loihica*, respectively, and culturing for one day. The ratio of the number of viable bacteria recovered from the coating surface to the number recovered from the blank glass slide surface was used to reflect the antibacterial rate of the coating. The laboratory antifouling test of the above coating involved immersing the coating in a suspension of *Chlorella sp.* for one day, and then observing the diatom adhesion on the coating surface using a laser confocal microscope in fluorescence mode.

[0025] The intrinsically alkaline, self-polishing, underwater superoleophobic marine antifouling coating of this invention is suitable for antifouling coatings in various applications such as ships, pipelines, marine industrial facilities, and aquaculture facilities in seawater environments. It can also be used as an antibacterial coating. In addition, this coating is inexpensive, environmentally friendly, and can be applied and cured at room temperature on a large scale. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the antifouling mechanism of the intrinsic alkaline self-polishing underwater superoleophobic marine antifouling coating of the present invention.

[0027] Figure 2 This is a SEM image of the surface morphology of the marine antifouling coating of the present invention after being soaked in artificial seawater for 3 days. Detailed Implementation

[0028] The present invention will be further described below through specific embodiments.

[0029] Preparation of acrylic resin matrix:

[0030] A mixture of methyl methacrylate, butyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, triisopropylsilyl methacrylate, and an initiator in different proportions was dissolved in a certain amount of butyl acetate solvent, and free radical polymerization was completed by heating. The formulations of acrylic resins with different monomer ratios are shown in Table 1.

[0031] Table 1

[0032]

[0033] Preparation of intrinsically alkaline, self-polishing, underwater superoleophobic marine antifouling coatings:

[0034] The above-mentioned acrylic resin, aminosiloxane, butyl acetate solvent, and a certain amount of triethylamine were mixed and stirred at room temperature for 15 minutes to obtain a uniform coating. After coating, the coating was cured at room temperature for 3 days. The coating formulations of Comparative Examples 1-3 and Examples 1-7 are shown in Table 2.

[0035] Table 2

[0036]

[0037]

[0038] The main difference between Comparative Example 1 and Example 4 is that the resin composition does not contain γ-methacryloxypropyltrimethoxysilane monomers that provide crosslinking, thus representing ordinary linear acrylic self-polishing resins; the main difference between Comparative Example 2 and Example 5 is that the resin composition does not contain triisopropylsilyl methacrylate monomers that provide in-situ hydrolysis, thus representing ordinary moisture-curing acrylic resins; the difference between Comparative Example 3 and Examples 1 and 2 is only in the type of aminosiloxane, used to compare the effect of the number of amino groups in the amino curing agent on the alkalinity of the coating surface.

[0039] The performance of Control Examples 1-3 and Examples 1-7 was characterized by indicator color development test, artificial seawater immersion test, and laboratory antibacterial and antifouling test, respectively. The results are shown in Table 3. The micro-nano structures formed on the coating surface of Control Example 1 and Examples 1, 4, and 5 are shown in the attached figure. Figure 2 As shown.

[0040] Table 3

[0041]

[0042] Data Analysis:

[0043] Comparing Comparative Example 3 with Examples 1 and 2 in Table 1, it can be seen that when using aminosiloxanes containing two or more amino groups, the resulting coating surface can form a highly alkaline hydration layer after hydrolysis; correspondingly, the antibacterial rate of the coating against Escherichia coli and Shewanella is greater than 95%; comparing Comparative Example 1 with Example 4, it can be seen that by introducing crosslinking monomers into the resin, the antifouling performance of the coating can be improved, and the amount of diatoms adhering to the coating surface is reduced by 65.6% compared to ordinary acrylic self-polishing resin; comparing Comparative Example 2 with Example 5, it can be seen that by introducing hydrolyzable monomers, the antifouling performance of the coating can be improved. The static and dynamic underwater oil contact angles of the coating are significantly improved compared to ordinary moisture-cured acrylic resins, achieving underwater superoleophobicity. Furthermore, data from Examples 1 and 3, Examples 4 and 6, and Examples 5 and 7 show that by changing the amount of aminosiloxane in the coating or introducing an appropriate amount of additional triethylamine, the microphase separation of aminosiloxane in the coating and the process of hydrolysis to generate micro-nano structures can be controlled, thereby improving the coating's ability to maintain its underwater oleophobicity under dynamic conditions, and further reducing the amount of diatoms adhering to the surface.

[0044] The above results demonstrate that the coating composition described in this invention can effectively achieve the intrinsic alkaline bactericidal effect on the coating surface, and also gives the coating stronger underwater oleophobicity and less surface diatom adhesion compared to ordinary acrylic self-polishing resin, thereby achieving excellent and stable underwater oleophobic and marine antifouling effects.

Claims

1. An intrinsically basic self-polishing underwater superoleophobic marine antifouling coating characterized by, The specific components are as follows in parts by weight: Acrylic resin: 40-80; Amino silicone: 2-20; Aliphatic tertiary amine: 0.5-7.5; Solvent: 20-45; Auxiliary agent: 0-5; The acrylic resin has the following general structure formula: ； I, I* are initiator composition structures; M1, M2, M3 are independently selected from H or CH3; R1, R2, R4 are selected from C1-C6 alkyl groups, R3 is selected from CH3 or CH2CH3, and X is selected from H, CH3, OCH3 or OCH2CH3; The amino silicone has the following general structure formula: ； R3 is selected from CH3 or CH2CH3, X is selected from H, CH3, OCH3 or OCH2CH3, and n is an integer ranging from 2 to 5.

2. The intrinsically base- self-polishable underwater superoleophobic marine antifouling coating according to claim 1, characterized in that, In the general structure formula of the acrylic resin, the mass ratio of the four monomers a, b, c, and d is (15-25):(30-60):(5-25):(5-25), totaling 100%, and the number average molecular weight of the resin is controlled between 5000 and 100000.

3. The intrinsically base- self-polishable underwater superoleophobic marine antifouling coating according to claim 1, characterized in that, The aliphatic tertiary amine is selected from one or more combinations of trimethylamine, triethylamine, N,N-dimethylethylamine, and N,N-diethylmethylamine.

4. The intrinsically base- self-polishable underwater superoleophobic marine antifouling coating according to claim 1, characterized in that, The solvent is selected from one or more combinations of amyl acetate, butyl acetate, ethyl acetate, ethanol, isopropyl alcohol, n-butyl alcohol, toluene, xylene, acetone, methyl isobutyl ketone, cyclohexanone, ethylene glycol dibutyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate.

5. The intrinsically base- self-polishable underwater superoleophobic marine antifouling coating according to claim 1, characterized in that, The auxiliary agent includes a leveling agent, a wetting agent, or a defoaming agent for paint.

6. The method for preparing the intrinsically base self-polishable underwater superoleophobic marine antifouling coating according to any one of claims 1-5, characterized in that, The specific steps are as follows: First, the acrylic resin is synthesized by a solution polymerization method; after the wet-cured acrylic resin is prepared, the amino silicone curing agent, the aliphatic tertiary amine, the solvent, and the auxiliary agent are added in sequence according to the proportions, and stirred and dispersed for 10-30 minutes to obtain the required paint.

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