Environment-friendly marine antifouling nano coating and preparation method thereof

Abstract

The invention discloses an environment-friendly marine antifouling nano coating and a preparation method thereof, and the nano coating comprises 10-20 parts of nano particles, 100 parts of aqueous film-forming resin, 10-20 parts of a low surface energy auxiliary agent, and 3-5 parts of a biological antifouling agent. The nano particles comprise modified inorganic nano particles grafted by 3-aminopropyltriethoxysilane and chitosan nano particles crosslinked by sodium tripolyphosphate, and the mass ratio of the modified inorganic nano particles to the chitosan nano particles is (2: 1)-(3: 1). According to the environment-friendly marine antifouling nano coating and the preparation method thereof, the characteristics of small size effect, high specific surface area and the like of a nano material are utilized, and the advantages of the nano material in the coating are fully embodied by controlling the particle size and the preparation process, such as improving the adhesive force, enhancing the strong acid and strong alkali resistance, blocking the invasion of chloride ions and the like; therefore, the overall quality of the coating is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to an environmentally friendly marine antifouling nano coating and a preparation method thereof. Background Art

[0002] Traditional marine antifouling coatings rely on toxic substances such as organotin and cuprous oxide. While they can effectively inhibit biofouling, they pose problems such as heavy metal leaching, marine ecotoxicity, and bioaccumulation, leading to restrictions on their use under international conventions. While the recently developed low-surface-energy antifouling coatings (such as silicone resins) offer improved environmental performance, they lack mechanical strength, have a short antifouling lifespan (typically less than two years), and significantly diminish their effectiveness in static environments. Summary of the Invention

[0003] The purpose of the present invention is to provide an environmentally friendly marine antifouling nano coating and a preparation method thereof to solve the above problems.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] An environmentally friendly marine antifouling nano coating comprises 10-20 parts of nanoparticles, 100 parts of a water-based film-forming resin, 10-20 parts of a low-surface-energy additive, and 3-5 parts of a bio-antifouling agent. The nanoparticles comprise modified inorganic nanoparticles grafted with 3-aminopropyltriethoxysilane and chitosan nanoparticles cross-linked with sodium tripolyphosphate. The mass ratio of the modified inorganic nanoparticles to the chitosan nanoparticles is (2:1) to (3:1).

[0006] Preferably, the mass of the 3-aminopropyltriethoxysilane is 1-3% of the mass of the inorganic nanoparticles, the inorganic nanoparticles are TiO2 or ZnO, and the mass of the sodium tripolyphosphate is 1 / 3 of the mass of the chitosan.

[0007] Preferably, the pH value of the nano coating is 7.5-8.5, the viscosity is 80-120 KU, and the average particle size is less than 100 nm.

[0008] Preferably, the aqueous film-forming resin is aqueous acrylic resin or polyurethane resin, the low surface energy additive is hydroxyl-terminated polysiloxane, and the bio-antifouling agent includes bio-extracted antifouling compounds, enzymes, antimicrobial peptides and alkaloids.

[0009] Preferably, it also includes a dispersant, a defoaming agent and a thickener. The dispersant is sodium polycarboxylate, and its mass is 1-2% of the mass of the modified nanoparticles. The defoaming agent is silicone, and its mass is 0.5% of the total mass of the nano coating. The thickener is xanthan gum, and its mass is 0.3-0.5% of the total mass of the nano coating.

[0010] A method for preparing an environmentally friendly marine antifouling nano coating comprises the following steps:

[0011] S1, preparing surface hydroxylated modified inorganic nanoparticles and chitosan nanoparticles respectively;

[0012] S2. Take the modified inorganic nanoparticles and chitosan nanoparticles, add deionized water, stir, disperse, and ultrasonically treat, and then add a dispersant to obtain a nanodispersion liquid a;

[0013] S3, diluting the pretreated aqueous film-forming resin, adding hydroxyl-terminated polysiloxane in three portions, and stirring until uniform to obtain resin emulsion b;

[0014] S4. Add the nano-dispersion liquid a prepared in step S2 to the resin emulsion b prepared in step S3. After sufficient stirring, add the bio-antifouling agent and disperse with ultrasound. After uniform dispersion, add the thickener and stir. Adjust the viscosity of the mixed solution c to 80-120 kU.

[0015] S5, grinding the mixed solution c prepared in step S5 to an average particle size of less than 100 nm using a sand mill, and then filtering to remove undispersed particles or impurities to obtain a coating slurry d;

[0016] S6. Adjust the pH of the coating slurry d to 7.5-8.5, and sterilize it to finally obtain the antifouling nano coating.

[0017] Preferably, step S1 is specifically:

[0018] S11, adding inorganic nanoparticles to an ethanol-water mixed solution, ultrasonically dispersing for 30 minutes, then adding 3-aminopropyltriethoxysilane as a coupling agent, magnetically stirring at 60°C for 2 hours, and after the coupling agent is hydrolyzed and grafted onto the surface of the inorganic nanoparticles, centrifuging at 8000 rpm for 10 minutes, washing with deionized water three times, and vacuum drying at 60°C for 4 hours to obtain surface hydroxylated modified inorganic nanoparticles;

[0019] S12, dissolving chitosan in acetic acid solution, adding sodium tripolyphosphate aqueous solution, preparing chitosan nanoparticles with a particle size of 50-100 nm through ionic crosslinking reaction, and ultrasonically dispersing for 20 minutes before use.

[0020] Preferably, steps S2 and S3 are specifically as follows:

[0021] S21. Take the modified inorganic nanoparticles and chitosan nanoparticles, add deionized water, stir at 500 rpm for 5 min, then perform high shear dispersion at 2000-3000 rpm, and then perform ultrasonic treatment for 30 min at a power of 300-500 W, in pulse mode, working for 3 s / rest for 2 s, until the solution is translucent and stably dispersed;

[0022] S22, adding a dispersant to the solution prepared in step S21, and continuing stirring for 10 minutes to obtain a nano-dispersion liquid a;

[0023] S31, select a water-based acrylic resin or polyurethane resin with a solid content of 40-50% as a water-based film-forming resin for pretreatment. If the viscosity is greater than 1000mPa·s, add 5-10% deionized water to dilute it and stir evenly. When the viscosity is less than 1000mPa·s, adjust the pH to 7-8 with ammonia or triethylamine;

[0024] S32, adding the pretreated aqueous film-forming resin to the reactor, stirring at a speed of 1000 rpm, and adding deionized water to dilute;

[0025] S33, adding hydroxyl-terminated polysiloxane as a low surface energy additive in three portions, with an interval of 5 minutes between each addition, and stirring until a uniform emulsion is formed;

[0026] S34, adding silicone as a defoaming agent, and stirring for 10 minutes to eliminate bubbles generated during the mixing process, to obtain resin emulsion b.

[0027] Preferably, step S4 is specifically:

[0028] S41, pouring the nano-dispersion liquid a prepared in step S2 into the resin emulsion b prepared in step S3, stirring at 800 rpm during the pouring process for 30 minutes until fully mixed;

[0029] S42, selecting one or more of biologically extracted antifouling compounds, enzymes, antimicrobial peptides, and alkaloids as biological antifouling agents and dissolving them in deionized water to prepare an antifouling solution;

[0030] S43, adding the anti-fouling solution prepared in step S2 to the solution prepared in step S1, and performing ultrasonic-assisted dispersion for 15 minutes to uniformly distribute the anti-fouling components, thereby obtaining a mixed solution c;

[0031] S44. Add xanthan gum as a thickener to the mixed solution c and stir to adjust the viscosity of the mixed solution c to 80-120 KU.

[0032] Preferably, steps S5 and S6 are specifically as follows:

[0033] S51, pouring the mixed solution c prepared in step S5 into a sand mill, controlling the feed rate to 5 L / min, and grinding in a cycle 2-3 times until the average particle size is less than 100 nm;

[0034] S52, filtering the material after grinding in step S51 through a 10 μm filter membrane to remove undispersed particles or impurities to obtain coating slurry d;

[0035] S61, adjusting the pH of the coating slurry d to 7.5-8.5 using a 5% sodium bicarbonate solution;

[0036] S62, adding 0.1% potassium sorbate as a biological antifouling agent, stirring for 10 minutes for sterilization, and finally obtaining the antifouling nano coating.

[0037] After adopting the above technical solution, the present invention has the following advantages compared with the background technology:

[0038] 1. The present invention provides an environmentally friendly marine antifouling nano-coating and a preparation method thereof. By utilizing the small size effect and high specific surface area of ​​nanomaterials and controlling the particle size and preparation process, the advantages of nanomaterials in coatings are fully reflected, such as improving adhesion, enhancing resistance to strong acids and alkalis, and blocking chloride ion intrusion, thereby improving the overall quality of the coating.

[0039] 2. The present invention provides an environmentally friendly marine antifouling nano-coating and a preparation method thereof, which uses one or more of biologically extracted antifouling compounds, enzymes, antimicrobial peptides and alkaloids as biological antifouling agents to form a multi-target antifouling mechanism (antibacterial, anti-algae, inhibition of larval attachment / metamorphosis, dissolution of adherents, etc.), which work together to achieve the effect of preventing biofouling. For example, the phenolic hydroxyl groups of natural tea polyphenol nanocomposites chelate with nanoparticles to form a slow-release system, avoiding sudden release of pollution, and the sodium tripolyphosphate cross-linked chitosan nanoparticles can be decomposed by marine microorganisms, reducing the risk of ecological accumulation.

[0040] 3. The present invention provides an environmentally friendly marine antifouling nano-coating and a preparation method thereof. The nano-scale double particles are used in synergistic combination to improve the antifouling performance. The modified inorganic nanoparticles increase the surface hydroxyl density, avoid nanoparticle agglomeration, and enhance the interfacial bonding with the resin. The chitosan nanoparticles adsorb microbial cell membranes through cationic charges and destroy their metabolism. The two are compounded in a certain mass ratio to form a dense nano-network, which physically blocks the penetration of biological larvae. The nano-coating has the characteristics of high-efficiency antifouling, environmental friendliness, and long-lasting weather resistance, and is suitable for scenes such as ships, marine engineering structures, and aquaculture cages.

[0041] 4. The present invention provides an environmentally friendly marine antifouling nano coating and a preparation method thereof. The hydroxyl-terminated polysiloxane is directional arranged on the coating surface, so that the surface energy is ≤22mN / m, reducing the adhesion strength of large organisms.

[0042] 5. The present invention provides an environmentally friendly marine antifouling nano-coating and a preparation method thereof. Inorganic nanoparticles are covalently bonded to a water-based film-forming resin through a silane coupling agent to improve the wear resistance of the coating. The aggregation of nanoparticles is effectively inhibited in an environment with a pH value of 7.5-8.5, ensuring no sedimentation during a long storage period. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A flow chart was prepared for the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] Example

[0046] Please refer to Figure 1 As shown, the present invention discloses an environmentally friendly marine antifouling nano coating, which includes 10-20 parts of nanoparticles, 100 parts of water-based film-forming resin, 10-20 parts of low surface energy additives, and 3-5 parts of biological antifouling agents. The nanoparticles include modified inorganic nanoparticles grafted with 3-aminopropyltriethoxysilane and chitosan nanoparticles cross-linked with sodium tripolyphosphate. The mass ratio of the modified inorganic nanoparticles to the chitosan nanoparticles is (2:1) to (3:1).

[0047] The mass of 3-aminopropyl triethoxysilane is 1-3% of the mass of the inorganic nanoparticles, the inorganic nanoparticles are TiO2 or ZnO, and the mass of sodium tripolyphosphate is 1 / 3 of the mass of chitosan.

[0048] The pH value of the nano coating is 7.5-8.5, the viscosity is 80-120KU, and the average particle size is less than 100nm.

[0049] The water-based film-forming resin adopts water-based acrylic resin or polyurethane resin, the low surface energy additive adopts hydroxyl-terminated polysiloxane, and the bio-antifouling agent includes bio-extracted antifouling compounds, enzymes, antimicrobial peptides and alkaloids.

[0050] Bio-extracted antifouling compounds: substances with antifouling activity extracted from organisms such as sponges and algae, such as:

[0051] Ianthelline (and related diterpenes): isolated from the sponge Ianthella basta, has significant antifouling activity and can inhibit the attachment and metamorphosis of barnacle larvae.

[0052] Oroidin and its derivatives (such as Ageliferin, Sventrin): Commonly found in sponges (such as Agelas), they have repellent and metamorphosis-inhibiting effects on the larvae of various fouling organisms.

[0053] Avarol / Avarone: Derived from the sponge Dysidea avara, it has broad-spectrum antimicrobial and anti-larval attachment activity.

[0054] Bromophenol compounds (such as phycocyanin): extracted from red algae (such as Rhodomela confervoides, Polysiphoniaspp.), have strong inhibitory effects on bacteria, diatoms and large fouling organism larvae.

[0055] Furanones (such as Halogenated furanones): Found from the red alga Deliseapulchra, they can interfere with the quorum sensing system of bacteria, thereby inhibiting biofilm formation and indirectly preventing the attachment of large organisms.

[0056] Zonarol / Isozonarol: Derived from the brown algae Dictyopteris zonarioides, it has activity in repelling barnacle larvae.

[0057] DidemninB (and related decapeptides): isolated from the ascidian Trididemnum solidum, with potent antifouling activity.

[0058] Tea polyphenols (and their nanocomplexes): Although they are mainly derived from terrestrial plants (tea), they are often made into nanocomplexes (such as with chitosan and metal oxides) for marine antifouling coating research due to their excellent antioxidant, antibacterial and larval adhesion inhibition capabilities.

[0059] Enzymes: proteases, lipases, etc., which can decompose adhesive substances secreted by marine organisms, such as:

[0060] Subtilisin: Derived from Bacillus bacteria, it can effectively degrade adhesive proteins (such as CP protein) secreted by organisms such as barnacles and mussels.

[0061] Trypsin: It is of animal origin and can also hydrolyze protein adhesive substances secreted by fouling organisms.

[0062] Keratinase: It can break down keratin and may be effective against the attachment structures of some fouling organisms.

[0063] Yeast lipase (such as Candidarugosalipase): can hydrolyze oils and esters, destroying lipid adhesive substances secreted by fouling organisms (such as diatoms and bacteria) or their protective layers.

[0064] Bacterial lipases (such as Pseudomonas fluorescens lipase): break down lipid components in biofilms.

[0065] Chitinase: It can decompose chitin and destroy the shells of barnacle larvae or the cell walls of certain microorganisms.

[0066] Alginate lyase: It specifically decomposes alginate and is effective in inhibiting the attachment of microalgae such as diatoms.

[0067] Antimicrobial peptides: Antimicrobial peptides that inhibit the growth and reproduction of microorganisms, thereby reducing the attachment of marine organisms, such as:

[0068] Mytilin: Isolated from mussels (Mytilus spp.), it has broad-spectrum antibacterial activity.

[0069] Myticin: From mussels (Mytilus spp.), it is an important innate immune defense molecule.

[0070] Clavanins (such as Clavanin A): derived from the sea squirt Styela clava, have potent antibacterial and antifungal activities.

[0071] Pardaxin: Derived from flounder skin secretions, it has antibacterial and surfactant properties and can disrupt cell membranes.

[0072] Styelins: Also derived from sea squirts (Styela spp.).

[0073] Alkaloids: Alkaloids with antifouling properties, such as:

[0074] Manzamine alkaloids (such as Manzamine A): isolated from a variety of sponges (such as Haliclona spp., Acanthostrongylophora spp.), have significant antibacterial, antifungal and barnacle larvae adhesion inhibitory activities.

[0075] Cephalotine and its derivatives: alkaloids extracted from mangrove plants Cephalotaxus spp. or related plants. Studies have shown that they have anti-attachment activity against barnacle larvae.

[0076] Caulerpin (and related indole alkaloids): isolated from the green alga Caulerpa spp., they have various biological activities, including antifouling potential.

[0077] The invention also includes a dispersant, a defoaming agent and a thickener. The dispersant is sodium polycarboxylate, and its mass is 1-2% of the mass of the modified nanoparticles. The defoaming agent is silicone, and its mass is 0.5% of the total mass of the nano coating. The thickener is xanthan gum, and its mass is 0.3-0.5% of the total mass of the nano coating.

[0078] The present invention also discloses a method for preparing an environmentally friendly marine antifouling nano coating, comprising the following steps:

[0079] S1, preparing surface hydroxylated modified inorganic nanoparticles and chitosan nanoparticles respectively;

[0080] Step S1 is specifically as follows:

[0081] S11. Add 10 g of inorganic nanoparticles (TiO2 or ZnO) to 50 mL of an ethanol-water mixed solution with a volume ratio of 3:1, and ultrasonically disperse for 30 minutes. Then add 3-aminopropyltriethoxysilane as a coupling agent (the mass of 3-aminopropyltriethoxysilane is 1-3% of the mass of the inorganic nanoparticles). Stir magnetically at 60°C for 2 hours. After the coupling agent is hydrolyzed and grafted onto the surface of the inorganic nanoparticles, centrifuge at 8000 rpm for 10 minutes, wash with deionized water three times, and vacuum dry at 60°C for 4 hours to obtain surface hydroxylated modified inorganic nanoparticles.

[0082] S12. Dissolve 5 g of chitosan in 100 mL of 1% acetic acid solution, add sodium tripolyphosphate aqueous solution (the mass of sodium tripolyphosphate is 1 / 3 of the mass of chitosan, 50 mL of aqueous solution), prepare chitosan nanoparticles with a particle size of 50-100 nm through ionic crosslinking reaction, and disperse them by ultrasound for 20 minutes before use.

[0083] S2. Take the modified inorganic nanoparticles and chitosan nanoparticles, add deionized water, stir, disperse, and ultrasonically treat, and then add a dispersant to obtain a nanodispersion liquid a;

[0084] The power needs to be controlled during ultrasonic treatment to avoid local overheating that may lead to particle agglomeration. The modified nanoparticles need to be used within 24 hours, and 0.5% propylene glycol needs to be added as an antifreeze for long-term storage.

[0085] S21, take 15g modified inorganic nanoparticles and 8g chitosan nanoparticles, add 200mL deionized water, first stir at a speed of 500rpm for 5min, then perform high shear dispersion at a speed of 2000-3000rpm, and then perform ultrasonic treatment for 30min, with a power of 300-500W, pulse mode, working 3s / rest 2s, until the solution is translucent and stable dispersed (without obvious precipitation), high shear dispersion and ultrasonic pulse are combined to break up nanoaggregates;

[0086] S22. Add a dispersant to the solution prepared in step S21 (using sodium polycarboxylate, and its mass is 1-2% of the mass of the modified nanoparticles. Sodium polycarboxylate can be directionally adsorbed on the particle surface to achieve electrostatic stabilization with a Zeta potential of >│30mV│), continue stirring for 10 minutes to stabilize the dispersion system, and obtain a nano-dispersion liquid a.

[0087] S3, diluting the pretreated aqueous film-forming resin, adding hydroxyl-terminated polysiloxane in three portions, and stirring until uniform to obtain resin emulsion b;

[0088] S31, add 300g of pretreated aqueous film-forming resin into the reactor, stir at a speed of 1000rpm, and add 100g of deionized water to dilute;

[0089] The specific pretreatment process of the water-based film-forming resin is as follows: select a water-based acrylic resin or polyurethane resin with a solid content of 40-50%. If the viscosity is high (>1000mPa·s), add 5-10% deionized water to dilute it, stir it evenly, and then use ammonia or triethylamine to adjust the pH to 7-8 to avoid acidic conditions that degrade natural ingredients such as chitosan.

[0090] S32, adding a total of 50 g of a low surface energy additive (hydroxyl-terminated polysiloxane, which is oriented on the coating surface to make the surface energy ≤ 22 mN / m and reduce the adhesion strength of large organisms by > 60%) in three portions, with an interval of 5 minutes between each addition, and stirring until a uniform emulsion is formed;

[0091] S33, adding a defoaming agent (organic silicon, with a mass of 0.5% of the total mass of the nano coating) and stirring for 10 minutes to eliminate bubbles generated during the mixing process to obtain a nano-dispersion liquid a.

[0092] S4. Add the nano-dispersion liquid a prepared in step S2 to the resin emulsion b prepared in step S3. After sufficient stirring, add the bio-antifouling agent and disperse with ultrasound. After uniform dispersion, add the thickener and stir. Adjust the viscosity of the mixed solution c to 80-120 kU.

[0093] S41, pouring the nano-dispersion liquid a prepared in step S2 into the resin emulsion b prepared in step S3, stirring at 800 rpm during the pouring process for 30 minutes until fully mixed;

[0094] S42, taking 10 g of a bio-antifouling agent (the bio-antifouling agent is any one or more of a bio-extracted antifouling compound, an enzyme, an antimicrobial peptide, and an alkaloid) and dissolving it in 50 mL of deionized water to prepare an antifouling solution;

[0095] One or more of bio-extracted antifouling compounds, enzymes, antimicrobial peptides and alkaloids are selected as bio-antifouling agents and dissolved in deionized water to prepare an antifouling solution;

[0096] S43, adding the anti-fouling solution prepared in step S2 to the solution prepared in step S1, and performing ultrasonic-assisted dispersion for 15 minutes to uniformly distribute the anti-fouling components, thereby obtaining a mixed solution c;

[0097] S44. Add a thickener (xanthan gum, 0.3-0.5% of the total mass of the nanocoating) to the mixed solution c and stir. Adjust the viscosity of the mixed solution c to 80-120 kU (4 cups, 25°C test) to meet the requirements of spray or brush application.

[0098] S5, grinding the mixed solution c prepared in step S5 to an average particle size of less than 100 nm using a sand mill, and then filtering to remove undispersed particles or impurities to obtain a coating slurry d;

[0099] S51, pouring the mixed solution c prepared in step S5 into a sand mill, controlling the feed rate to 5 L / min, and grinding in a cycle 2-3 times until the average particle size is less than 100 nm;

[0100] S52 , filtering the material after grinding in step S51 through a 10 μm filter membrane to remove undispersed particles or impurities, thereby obtaining coating slurry d.

[0101] S6. Adjust the pH of the coating slurry d to 7.5-8.5, and sterilize it to finally obtain the antifouling nano coating.

[0102] S61. Use 5% sodium bicarbonate solution to adjust the pH of coating slurry d to 7.5-8.5 to inhibit the aggregation of nanoparticles and ensure a storage period of more than 12 months without sedimentation (viscosity maintained at 80-120 KU);

[0103] S62. Add 0.1% potassium sorbate as a biological antifouling agent, stir for 10 minutes for sterilization, and finally obtain the antifouling nano coating. Potassium sorbate and chitosan nanoparticles synergistically inhibit the growth of mold and extend the service life after opening.

[0104] The quality control and detection methods of the nano coating prepared in this embodiment are specifically as follows:

[0105] 1. Dispersion stability:

[0106] There was no stratification after standing for 72 hours, and the sedimentation rate was less than 5% after centrifugation (3000 rpm, 15 min);

[0107] - Particle size distribution: D50 < 80 nm, PDI (polydispersity index) < 0.2.

[0108] 2. Antifouling performance test:

[0109] Static hanging board test: Immerse the coated test piece in natural seawater and regularly observe the amount of algae and barnacles attached. The requirement is that the attached area is less than 10% within 3 months.

[0110] Photocatalytic activity: Methyl orange degradation rate test (simulated sunlight irradiation for 4 hours, degradation rate>80%).

[0111] 3. Environmental protection and safety:

[0112] Heavy metal detection (ICP-MS): Cu, Sn, Pb, etc. content <10ppm;

[0113] Marine toxicity test: According to ISO 10533 standard, EC50 for luminous bacteria (Vibrio fischeri) is greater than 1000 mg / L.

[0114] 4. Construction adaptability:

[0115] Substrate pretreatment: Metal substrates need to be sandblasted to remove rust (Sa2.5 level), and concrete substrates need to be coated with epoxy primer to enhance adhesion;

[0116] Construction conditions: humidity <85%, temperature 10-30℃, avoid construction in rainy days or high salt fog environment.

[0117] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An environmentally friendly marine antifouling nano coating, characterized by: The invention comprises 10-20 parts of nanoparticles, 100 parts of aqueous film-forming resin, 10-20 parts of low surface energy additives, and 3-5 parts of biofouling agent. The nanoparticles comprise modified inorganic nanoparticles grafted with 3-aminopropyltriethoxysilane and chitosan nanoparticles cross-linked with sodium tripolyphosphate. The mass ratio of the modified inorganic nanoparticles to the chitosan nanoparticles is (2:1) to (3:1).

2. The environmentally friendly marine antifouling nano coating according to claim 1, characterized in that: The mass of the 3-aminopropyl triethoxysilane is 1-3% of the mass of the inorganic nanoparticles, the inorganic nanoparticles are TiO2 or ZnO, and the mass of the sodium tripolyphosphate is 1 / 3 of the mass of the chitosan.

3. The environmentally friendly marine antifouling nano coating according to claim 1, characterized in that: The pH value of the nano coating is 7.5-8.5, the viscosity is 80-120 KU, and the average particle size is less than 100 nm.

4. The environmentally friendly marine antifouling nano-coating according to claim 1, characterized in that: The water-based film-forming resin is water-based acrylic resin or polyurethane resin, the low surface energy additive is hydroxyl-terminated polysiloxane, and the bio-antifouling agent includes bio-extracted antifouling compounds, enzymes, antimicrobial peptides and alkaloids.

5. The environmentally friendly marine antifouling nano-coating according to claim 1, characterized in that: The invention also includes a dispersant, a defoaming agent and a thickener. The dispersant is sodium polycarboxylate, and its mass is 1-2% of the mass of the modified nanoparticles. The defoaming agent is silicone, and its mass is 0.5% of the total mass of the nano coating. The thickener is xanthan gum, and its mass is 0.3-0.5% of the total mass of the nano coating.

6. A method for preparing an environmentally friendly marine antifouling nano coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, preparing surface hydroxylated modified inorganic nanoparticles and chitosan nanoparticles respectively; S2. Take the modified inorganic nanoparticles and chitosan nanoparticles, add deionized water, stir, disperse, and ultrasonically treat, and then add a dispersant to obtain a nanodispersion liquid a; S3, diluting the pretreated aqueous film-forming resin, adding hydroxyl-terminated polysiloxane in three portions, and stirring until uniform to obtain resin emulsion b; S4. Add the nano-dispersion liquid a prepared in step S2 to the resin emulsion b prepared in step S3. After sufficient stirring, add the bio-antifouling agent and disperse with ultrasound. After uniform dispersion, add the thickener and stir. Adjust the viscosity of the mixed solution c to 80-120 kU. S5, grinding the mixed solution c prepared in step S5 to an average particle size of less than 100 nm using a sand mill, and then filtering to remove undispersed particles or impurities to obtain a coating slurry d; S6. Adjust the pH of the coating slurry d to 7.5-8.5, and sterilize it to finally obtain the antifouling nano coating.

7. The method for preparing an environmentally friendly marine antifouling nano-coating according to claim 1, characterized in that: Step S1 is specifically as follows: S11, adding inorganic nanoparticles to an ethanol-water mixed solution, ultrasonically dispersing for 30 minutes, then adding 3-aminopropyltriethoxysilane as a coupling agent, magnetically stirring at 60°C for 2 hours, and after the coupling agent is hydrolyzed and grafted onto the surface of the inorganic nanoparticles, centrifuging at 8000 rpm for 10 minutes, washing with deionized water three times, and vacuum drying at 60°C for 4 hours to obtain surface hydroxylated modified inorganic nanoparticles; S12, dissolving chitosan in acetic acid solution, adding sodium tripolyphosphate aqueous solution, preparing chitosan nanoparticles with a particle size of 50-100 nm through ionic crosslinking reaction, and ultrasonically dispersing for 20 minutes before use.

8. The method for preparing an environmentally friendly marine antifouling nano coating according to claim 1, wherein: Steps S2 and S3 are specifically as follows: S21. Take the modified inorganic nanoparticles and chitosan nanoparticles, add deionized water, stir at 500 rpm for 5 min, then perform high shear dispersion at 2000-3000 rpm, and then perform ultrasonic treatment for 30 min at a power of 300-500 W, in pulse mode, working for 3 s / rest for 2 s, until the solution is translucent and stably dispersed; S22, adding a dispersant to the solution prepared in step S21, and continuing stirring for 10 minutes to obtain a nano-dispersion liquid a; S31, select a water-based acrylic resin or polyurethane resin with a solid content of 40-50% as a water-based film-forming resin for pretreatment. If the viscosity is greater than 1000mPa·s, add 5-10% deionized water to dilute it and stir evenly. When the viscosity is less than 1000mPa·s, adjust the pH to 7-8 with ammonia or triethylamine; S32, adding the pretreated aqueous film-forming resin to the reactor, stirring at a speed of 1000 rpm, and adding deionized water to dilute; S33, adding hydroxyl-terminated polysiloxane as a low surface energy additive in three portions, with an interval of 5 minutes between each addition, and stirring until a uniform emulsion is formed; S34, adding silicone as a defoaming agent, and stirring for 10 minutes to eliminate bubbles generated during the mixing process, to obtain resin emulsion b.

9. The method for preparing an environmentally friendly marine antifouling nano coating according to claim 1, wherein: Step S4 is specifically as follows: S41, pouring the nano-dispersion liquid a prepared in step S2 into the resin emulsion b prepared in step S3, stirring at 800 rpm during the pouring process for 30 minutes until fully mixed; S42, selecting one or more of biologically extracted antifouling compounds, enzymes, antimicrobial peptides, and alkaloids as biological antifouling agents and dissolving them in deionized water to prepare an antifouling solution; S43, adding the anti-fouling solution prepared in step S2 to the solution prepared in step S1, and performing ultrasonic-assisted dispersion for 15 minutes to uniformly distribute the anti-fouling components, thereby obtaining a mixed solution c; S44. Add xanthan gum as a thickener to the mixed solution c and stir to adjust the viscosity of the mixed solution c to 80-120 KU.

10. The method for preparing an environmentally friendly marine antifouling nano coating according to claim 1, characterized in that: Steps S5 and S6 are specifically as follows: S51, pouring the mixed solution c prepared in step S5 into a sand mill, controlling the feed rate to 5 L / min, and grinding in a cycle 2-3 times until the average particle size is less than 100 nm; S52, filtering the material after grinding in step S51 through a 10 μm filter membrane to remove undispersed particles or impurities to obtain coating slurry d; S61, adjusting the pH of the coating slurry d to 7.5-8.5 using a 5% sodium bicarbonate solution; S62, adding 0.1% potassium sorbate as a biological antifouling agent, stirring for 10 minutes for sterilization, and finally obtaining the antifouling nano coating.

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