A water-based environmentally friendly antifouling coating for marine environments, its preparation method and application

Abstract

This invention belongs to the technical field of marine organic antifouling coatings, specifically disclosing a water-based environmentally friendly antifouling coating for marine environments, its preparation method, and its application. The water-based environmentally friendly antifouling coating for marine environments includes component A and component B. Component A includes water-based epoxy-modified silicone resin, graphene oxide, inorganic fillers, additives, and deionized water; component B is a silane coupling agent. The additives include film-forming aids, substrate wetting agents, water-based dispersants, water-based defoamers, thickeners, and leveling agents. The coating of this invention is antibacterial and corrosion-resistant, and also possesses hydrophobic properties, thus exhibiting excellent antifouling performance. It can be synthesized through simple ultrasonic vibration, mechanical shearing, and grinding and stirring, making the preparation method simple and efficient. Furthermore, neither the preparation nor the service process generates pollution, demonstrating good environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of marine organic antifouling coating technology, specifically to a water-based environmentally friendly antifouling coating for marine environments, its preparation method, and its application. Background Technology

[0002] Since the 1960s, cage aquaculture technology has been widely adopted in marine aquaculture, which has become the fastest-growing segment of the food economy. By the end of 2022, aquaculture production had surpassed wild seafood catches, highlighting its undeniable importance. However, fouling organisms attach to aquaculture facilities, negatively impacting product production. The complex biofouling communities that evolve on the netted surfaces indirectly lead to further biofouling, providing a breeding ground for harmful microorganisms. These fouling communities breed bacteria and parasites, reducing product quality and, in severe cases, causing stunted growth or even death, thus negatively impacting economic returns. Traditional marine aquaculture requires periodically towing the nets back to shore for mechanical cleaning, a process that prolongs the aquaculture cycle and significantly increases costs.

[0003] Current mainstream antifouling methods, whether for ships or fishing nets, involve the use of pesticide-based antifouling coatings. The pesticides in the coating slowly penetrate into the seawater, thus reducing fouling on the surface of the equipment. Copper-based antifouling coatings, using cuprous oxide as a bactericide, are currently the most widely used coatings in the field of fishing net antifouling. However, with the continuous expansion of marine aquaculture into deep-sea areas and increasingly stringent legislation restricting the use of bactericides in the food industry, new antifouling methods must effectively control the evolution and development of fouling communities while meeting environmental, social, and economic needs. Due to environmental policy pressures, much research has focused on developing pesticide-free "fouling-release" coatings.

[0004] Antifouling coatings for fishing nets include solvent-based and water-based types, with water-based coatings better meeting environmental and safety requirements. Additionally, coatings based on fluoropolymers and silicone resins are a major alternative to antifouling coatings containing bactericides; these are often referred to as "fouling-desorption" antifouling coatings. Their lower surface energy and elastic modulus result in weaker adhesion of fouling organisms to the surface of these coatings. Fluorocarbon resins only dissolve well in fluorinated solvents, making the production of low-VOC (volatile organic compound) products challenging. Furthermore, their reactants may still contain isocyanates, thus requiring further improvements in environmental friendliness and application performance.

[0005] Patent CN201710528984 discloses a method for preparing a low surface energy waterborne polyurethane / nano-SiO2 antifouling coating material. It produces a low surface energy antifouling coating material with a static water contact angle as high as 109.36°, which is green and environmentally friendly, has good adhesion to the surface of equipment such as ships, and has excellent mechanical properties. However, the method of dual modification of waterborne polyurethane is relatively complicated and not easy to be applied on a large scale.

[0006] It is evident that using the above methods to achieve functional coatings is either complex, polluting, and inconvenient. How to efficiently, simply, and without pollution prepare highly effective antifouling coatings is currently a hot research topic and a significant challenge. Summary of the Invention

[0007] In view of the shortcomings of existing low surface energy corrosion-resistant coatings, one of the objectives of this invention is to provide a water-based environmentally friendly antifouling coating for marine environments, which has the characteristics of good antifouling performance, environmentally friendly service process, and simple preparation.

[0008] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0009] A water-based environmentally friendly antifouling coating for marine environments includes component A and component B. Component A includes water-based epoxy-modified silicone resin, graphene oxide, inorganic fillers, additives, and deionized water. Component B is a silane coupling agent. The additives include film-forming aids, substrate wetting agents, water-based dispersants, water-based defoamers, thickeners, and leveling agents.

[0010] This invention uses water-based silicone resin emulsion as the main raw material, which is environmentally friendly and readily available. When used in conjunction with a silane coupling agent, it achieves room-temperature curing, reducing process difficulty and cost. The coating prepared according to the formula of this invention meets the requirements of low surface energy (dynamic antifouling) and possesses the excellent mechanical and corrosion-resistant properties of the added fillers (including graphene oxide and inorganic fillers). This invention provides a pollution-free, low-surface-energy, and corrosion-resistant antifouling coating, ensuring good service performance during operation.

[0011] Preferably, component A comprises, by mass percentage: 43-47% waterborne epoxy-modified silicone resin, 0.05-0.15% graphene oxide, 35-38% inorganic filler, 1-3% film-forming aid, 0.4-0.6% substrate wetting agent, 3-5% waterborne dispersant, 0.5-1.5% waterborne defoamer, 0.1-0.3% thickener, 0.5-1.5% leveling agent, and the balance being deionized water.

[0012] Furthermore, in component A, the content of graphene oxide is 0.10 wt%, at which point the coating exhibits optimal corrosion resistance.

[0013] Preferably, the mass ratio of component A to component B is (20-30):1.

[0014] Preferably, the inorganic filler includes talc, mica powder, iron oxide red, and zinc phosphate tetrahydrate.

[0015] Preferably, the waterborne epoxy-modified silicone resin has an epoxy value of 0.02 to 0.08, a solid content of 50 ± 1%, and a viscosity cp ≤ 600 mPa·s (test conditions are 25℃, 1# 12 rpm, NDJ-8S).

[0016] A second objective of this invention is to provide a method for preparing the above-mentioned water-based environmentally friendly antifouling coating for marine environments, comprising the following steps:

[0017] S1. Place graphene oxide and deionized water in a container and ultrasonically vibrate at 30-50 kHz for 1 hour to form an aqueous solution of graphene oxide.

[0018] S2. Add the film-forming aid, substrate wetting agent, aqueous dispersant, and aqueous defoamer to the above aqueous solution in sequence, place them in a mixing tank, and shear and stir at a low speed of 400-600 r / min for 15-30 min;

[0019] S3. Add the inorganic filler to the mixing tank in S2, and grind and stir at high speed of 2500-3500 r / min for 30-50 min to obtain the color paste;

[0020] S4. Place the waterborne epoxy modified silicone resin in the mixing tank containing the color paste in S3, and shear and stir at a low speed of 200-400 r / min for 30-50 min. Add thickener and leveling agent during the stirring process until the stirring is finished. Filter, and store in a can for later use.

[0021] S5. Mix the coating obtained in S4 with the silane coupling agent, and shear at a low speed of 200-400 r / min for 4-8 min until the mixture is uniform. Then let it stand for 15-25 min to mature before spraying.

[0022] Preferably, in step S5, after the spraying operation is completed, the surface is dry in 1 day and fully dry in 7 days at room temperature.

[0023] A third objective of this invention is to provide the application of the aforementioned water-based environmentally friendly antifouling coating in marine environments in the field of shipbuilding and marine engineering. Specifically, the coating is sprayed onto the surface of aquaculture facilities (such as fishing nets, cages, etc.) to enhance their antifouling and antimicrobial adhesion properties, reducing or even eliminating the need for periodic hauling back to shore for mechanical cleaning, effectively shortening the aquaculture cycle and reducing aquaculture costs.

[0024] The present invention has the following beneficial effects:

[0025] This invention successfully synthesizes a water-based antifouling and corrosion-resistant composite coating through simple ultrasonic vibration, mechanical shearing, and grinding / stirring methods. The coating exhibits excellent hydrophobic properties, demonstrates outstanding corrosion resistance in seawater, maintains stable performance even after long-term immersion in seawater, and effectively reduces microbial adhesion. This invention enriches the water-based antifouling coating material system, offering advantages such as simplicity, environmental friendliness, and wide applicability, and possesses significant application potential in mariculture, shipbuilding, and marine engineering. Attached Figure Description

[0026] Figure 1 Electron micrograph of graphene oxide used in the water-based antifouling coating prepared in Example 1.

[0027] Figure 2 The image shows a scanning electron microscope (SEM) image of the cross-section of the film-forming coating of the water-based antifouling coating prepared in Example 1.

[0028] Figure 3 Electrochemical polarization curve of the film-forming coating of the water-based antifouling coating prepared in Example 1.

[0029] Figure 4 The 0s water contact angle of the water-based antifouling coating film prepared in Example 1.

[0030] Figure 5 The image shows the electrochemical Nyquist plot of the waterborne antifouling coating film prepared in Example 1 in simulated seawater; the left plot is the Nyquist plot at a large scale; the right plot is the Nyquist plot at a small scale.

[0031] Figure 6 The image shows the electrochemical Bode plot of the waterborne antifouling coating film prepared in Example 1 in simulated seawater; in the figure, the left side is the impedance |Z|-frequency variation plot; and the right side is the phase angle variation plot.

[0032] Figure 7 The XRD pattern of the water-based antifouling coating film prepared in Example 1 after immersion in simulated seawater for 28 days.

[0033] Figure 8 Electrochemical Nyquist plot of the coating prepared for Comparative Example 1 in simulated seawater.

[0034] Figure 9 Electrochemical Bode plot of the coating prepared for Comparative Example 1 in simulated seawater.

[0035] Figure 10 Microscopic views of coatings prepared with different amounts of silane coupling agent in Comparative Example 2.

[0036] Figure 11Microscopic views of the coatings prepared at different curing times in Comparative Example 3. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] A water-based environmentally friendly antifouling coating for marine environments includes component A and component B. Component A includes the components shown in the table below, and component B is a curing agent, a silane coupling agent.

[0040] Composition table of component A

[0041]

[0042] The preparation method of the water-based environmentally friendly antifouling coating for marine environments is as follows:

[0043] S1. Place components numbered 1-2 in a container and sonicate at 40 kHz for 1 hour to form an aqueous solution of graphene oxide;

[0044] S2. Add components numbered 3-6 sequentially to the above aqueous solution, place in a mixing tank, and shear and stir at a low speed of 500r / min for 20min;

[0045] S3. Add items numbered 7-10 sequentially to the mixing tank in S2, and grind and stir at 3000 r / min for 40 min to obtain the color paste;

[0046] S4. Place water component 11 into the mixing tank containing the color paste in S3, and shear mix at a low speed of 300r / min for 40min. Add components 12-13 during the mixing process until the mixing is finished. Filter the paint in the mixing tank with 100-mesh filter paper, and store it in a can for later use.

[0047] S5. Mix the coating obtained in S4 with the silane coupling agent at a mass ratio of 25:1, shear at a low speed of 300r / min for 5min until the mixture is uniform, and then let it stand for 20min to mature before spraying.

[0048] After the prepared coating is sprayed, it is surface dry in 1 day and fully dry in 7 days at room temperature, forming a water-based anti-fouling and corrosion-resistant organic coating.

[0049] The performance of the film-forming coating was tested using the following methods:

[0050] 1. Film morphology observation: Observe the film morphology of the coating under a scanning electron microscope.

[0051] 2. Corrosion performance test: Potentiodynamic polarization test was performed on an electrochemical workstation. The sample size was 10×10×1mm.

[0052] 3. Hydrophobicity test: The hydrophobicity of the coating was tested using a water contact angle tester.

[0053] 4. Coating Phase Analysis: X-ray diffraction was used to analyze the phase composition of the coating before and after service. Specifically, a four-week simulated seawater immersion experiment was conducted on the film-forming coating to analyze the corrosion behavior of the coating in seawater, and XRD phase analysis was performed on the coating before and after immersion.

[0054] The performance test results are as follows:

[0055] like Figure 1 As shown, the microstructure of graphene oxide, a nanofiller in the coating composition, is clearly visible. This graphene oxide exhibits wrinkled, sheet-like nanoscale materials. The addition of this nanoscale filler contributes to the excellent nanoscale properties of the composite coating. Figure 2 The image shows the microstructure of the film-forming coating. It can be seen that the fillers in the coating are tightly connected together, and there is no obvious incompatibility. This indicates that the addition of fillers (including graphene oxide and inorganic fillers) has no adverse effect on the coating. On the contrary, it can make the coating have better mechanical and nano properties.

[0056] The results of the potential polarization test are as follows Figure 3 As shown, the film-forming coating exhibits excellent corrosion resistance, with a corrosion potential of approximately -0.1 mV and a corrosion current of approximately 10 mV. -8 On the order of A.

[0057] like Figure 4 It can be seen that the water contact angle of the coating at 0s is 93.25°. This indicates that the coating has hydrophobic properties at the first moment of water contact, thus giving it good antifouling and corrosion resistance.

[0058] Figure 5 The Nyquist plot of the coating. Figure 6 The Bode plot of the coating shows that the impedance arc gradually decreases with time, and the impedance value also decreases with increasing immersion time. However, overall, no second arc feature appears in the Nyquist plot of the coating during the 28-day immersion period, and no second time constant appears in the Bode plot of the coating. Theoretically, the coating was not damaged by seawater during the 28-day immersion, and no corrosion products were generated. Figure 7 Phase analysis also showed that no other phases were formed in the coating, meaning no new substances were generated. In conclusion, the coating provides excellent protection to the substrate in seawater.

[0059] Comparative Example 1

[0060] This comparative example uses different contents of graphene oxide to prepare coatings. The specific graphene oxide contents tested are 0 wt%, 0.01 wt%, 0.05 wt%, 0.1 wt%, and 0.15 wt% (marked as G0, G1, G5, G10, and G15 in the figure, respectively). Figure 8 The Nyquist plot of the coating. Figure 9 The Bode plot of the coating shows that the impedance arc is the largest and the corrosion resistance is the best when the graphene oxide content is 0.1 wt% (G10).

[0061] Comparative Example 2

[0062] In this comparative example, an excess of silane coupling agent was added to prepare the coating film, such as... Figure 10 As shown, the left figure is the film morphology under the condition of appropriate amount of silane coupling agent (within the preferred range), and the right figure is the film morphology under the condition of excessive amount of silane coupling agent. It can be seen that the film morphology under the condition of appropriate amount is relatively dense and there are no excessively large pores. However, the addition of excessive silane coupling agent makes the film formation effect of the coating poor and is not conducive to production and use.

[0063] Comparative Example 3

[0064] This comparative experiment tested different curing times (10, 20, 30, 40, 50, and 60 min) for coating preparation. Microscopic views of the formed coatings are shown below. Figure 11 As shown in the figure, different curing times result in different film-forming effects, with 20 minutes yielding the best film-forming effect.

[0065] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims of the present invention, will be protected by patent law.

Claims

1. A water-based, environmentally friendly antifouling coating for marine environments, characterized in that: Includes component A and component B; Component A, by mass percentage, comprises: 43-47% waterborne epoxy-modified silicone resin, 0.05-0.15% graphene oxide, 35-38% inorganic filler, 1-3% film-forming aid, 0.4-0.6% substrate wetting agent, 3-5% waterborne dispersant, 0.5-1.5% waterborne defoamer, 0.1-0.3% thickener, 0.5-1.5% leveling agent, with the balance being deionized water; Component B is a silane coupling agent; the mass ratio of component A to component B is (20-30):

1.

2. The water-based environmentally friendly antifouling coating for marine environments according to claim 1, characterized in that: In component A, the content of graphene oxide is 0.10 wt%.

3. The water-based environmentally friendly antifouling coating for marine environments according to claim 1, characterized in that: The inorganic filler includes talc, mica powder, iron oxide red, and zinc phosphate tetrahydrate.

4. The water-based environmentally friendly antifouling coating for marine environments according to claim 1, characterized in that: The waterborne epoxy-modified silicone resin has an epoxy value of 0.02 to 0.08, a solid content of 50 ± 1%, and a viscosity of ≤ 600 mPa·s.

5. The method for preparing the water-based environmentally friendly antifouling coating for marine environments according to any one of claims 1-4, characterized in that: Includes the following steps: S1. Place graphene oxide and deionized water in a container and ultrasonically vibrate at 30-50 kHz for 1 hour to form an aqueous solution of graphene oxide. S2. Add the film-forming aid, substrate wetting agent, aqueous dispersant, and aqueous defoamer to the above aqueous solution in sequence, place them in a mixing tank, and shear and stir at a low speed of 400-600 r / min for 15-30 min; S3. Add the inorganic filler to the mixing tank in S2, and grind and stir at high speed of 2500-3500 r / min for 30-50 min to obtain the color paste; S4. Place the waterborne epoxy modified silicone resin in the mixing tank containing the color paste in S3, and shear and stir at a low speed of 200-400 r / min for 30-50 min. Add thickener and leveling agent during the stirring process until the stirring is finished. Filter, and store in a can for later use. S5. Mix the coating obtained in S4 with the silane coupling agent, and shear at a low speed of 200-400 r / min for 4-8 min until the mixture is uniform. Then let it stand for 15-25 min to mature before spraying.

6. The method for preparing a water-based environmentally friendly antifouling coating for a marine environment according to claim 5, characterized in that: In step S5, after the spraying operation is completed, it takes 1 day to achieve surface dryness and 7 days to achieve full dryness at room temperature.

7. The application of the waterborne environmentally friendly antifouling coating for marine environments as described in any one of claims 1-4 in the field of shipbuilding and marine engineering.

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