Biodegradable marine antifouling paint as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of marine coatings, and particularly relates to a biodegradable marine antifouling coating as well as a preparation method and application thereof. The talcum powder is used as a nucleating agent to modify poly (epsilon-caprolactone), and after the talcum powder is added, the degradation efficiency, crystallinity and crystal size of the poly (epsilon-caprolactone) can be improved. The size of poly epsilon-caprolactone spherulites is reduced and is uniform, the degradation rate is accelerated, and the release of the antifouling agent is more facilitated. In addition, the talcum powder can control release of the antifouling agent, and the phenomenon of burst release of the antifouling agent in a short time is avoided. The biodegradable marine antifouling paint disclosed by the invention can achieve an antifouling effect as long as 3 months in a vigorous fouling growth season, and a theoretical basis and practical significance are provided for biodegradable environment-friendly antifouling paint.

Description

Technical Field

[0001] The invention belongs to the technical field of marine coatings, and in particular relates to a biodegradable marine antifouling coating and a preparation method and application thereof. Background Art

[0002] Marine biofouling is caused by the continuous sedimentation, attachment and poor reproduction of microorganisms, plants and animals in the ocean on the surface of marine solid facilities such as the bottom of ships, aquaculture facilities, oil platforms, etc. Marine biofouling is extremely harmful to ships sailing in the ocean and the development and utilization of marine resources. Some of these fouling organisms attach and grow on the bottom of the ship, which increases the quality and navigation resistance of the ship, accelerates the degree of metal corrosion, leads to high fuel consumption and high maintenance costs, and may even cause safety accidents; some organisms grow in metal pipes, causing pipe blockage, affecting the normal operation of equipment, and some will attach to nets and cages, blocking the mesh, affecting the oxygen circulation of aquaculture organisms and the exchange of nutrients, leading to the death of marine aquatic products, causing huge economic losses. In addition to economic losses, marine fouling will also pollute the ecological environment. When marine fouling organisms attach to the hull and are brought into new ports and sea areas, different water environments will cause hazards such as biological invasion. Therefore, how to effectively solve marine biofouling has become an important issue in protecting the marine environment and resource development.

[0003] The antifouling agent 4,5-dichloro-2-octyl-4-isothiazoline-3-one, referred to as DCOIT, has shown broad-spectrum and high-efficiency characteristics in laboratory tests, field tests and actual ship applications. It not only has excellent bactericidal and algaecidal properties, but also has a good inhibitory and killing effect on barnacles, and can effectively prevent marine organisms from attaching and fouling. In addition, DCOIT can be quickly degraded in the environment, rarely enriched in the marine environment, has a small accumulation effect in organisms, and has little harm to organisms other than the target. It has the advantages of environmental protection and low toxicity, can provide good protection for ship antifouling, and has broad application prospects in antifouling materials.

[0004] At present, polymer resin is usually used as a substrate, such as poly-ε-caprolactone (PCL) substrate, and antifouling coating is prepared with antifouling agent and applied on the hull to solve the marine biofouling. However, polymer resin is non-degradable or the degradation rate is difficult to control, which makes it difficult to release the antifouling agent evenly. Even for self-polishing antifouling polymers, the self-renewal of its surface depends largely on the movement of the ship and the scouring of the surrounding seawater. It is difficult to effectively coordinate the solubility of the polymer after hydrolysis, resulting in a decrease in the release rate of the antifouling agent in the static stage, and its effectiveness cannot be fully exerted. And the release of non-degradable materials into the ocean will cause serious marine plastic garbage pollution. After completing the task of the antifouling stage, it will cause marine plastic pollution in the seawater, aggravating the harm to the marine environment.

[0005] In addition, since the crystallization performance of the PCL substrate directly affects the degradation rate of PCL, PCL has the disadvantages of high crystallinity, large crystal size, and uncontrollable degradation rate, making it difficult for PCL to have good antifouling effects relying solely on its own properties. Moreover, its film-forming performance is poor and it is extremely easy to fall off from the substrate. The small molecules generated by the hydrolysis of PCL do not have sufficient antifouling toxicity, and antifouling agents need to be added to ensure the antifouling effect.

[0006] Currently, the PCL substrate and antifouling agents are usually used in combination to improve the antifouling effect. However, during the combined use of the PCL substrate and antifouling agents, there will be a problem of burst release of the antifouling agent, that is, most of the antifouling agent will be released during the initial release process. As a result, after the release rate stabilizes in the later stage, there is not enough quantity and concentration of the antifouling agent, seriously affecting the inhibitory effect on biofouling, unable to achieve ideal antifouling results, and greatly shortening the antifouling period. et al. prepared a block degradable copolymer of caprolactone and anhydride by bulk polymerization. After compounding with the pesticide diuron, the antifouling agent can be released stably, but the effective time of the coating is too short and it is almost released completely within two months. Summary of the Invention

[0007] To solve the above problems, the present invention provides a biodegradable marine antifouling coating and its preparation method and application. The biodegradable marine antifouling coating obtained from poly(ε-caprolactone), talcum powder and antifouling agents can solve the burst release of the antifouling agent when poly(ε-caprolactone) is used as the base, enable the antifouling agent to be released stably, improve the antifouling effect on ships, and still have good antifouling effects for more than 3 months.

[0008] To achieve the above object, the technical solution of the present invention is as follows.

[0009] The first aspect of the present invention provides a preparation method of a biodegradable marine antifouling coating, including the following steps:

[0010] At 60°C to 80°C, poly(ε-caprolactone) and talcum powder are mixed and subjected to a modification reaction in an organic solvent for 30 min to 60 min. The talcum powder is used to reduce the crystal ball size after the crystallization of poly(ε-caprolactone). After the reaction is completed, the organic solvent is removed to obtain a polyester-based substrate;

[0011] The polyester-based substrate is heated to a molten state, and an antifouling agent is added and mixed for reaction to obtain the biodegradable marine antifouling coating;

[0012] The mass ratio of poly(ε-caprolactone), talcum powder and antifouling agent is 72.5 - 82.5:7.5:10 - 20.

[0013] In the present invention, by using talcum powder as a nucleating agent, poly(ε-caprolactone) is modified at 60 °C to 80 °C for 30 min to 60 min. The talcum powder can improve the degradation efficiency, crystallinity and crystal size of poly(ε-caprolactone), reduce the spherulite size of poly(ε-caprolactone) to no more than 10 μm, and make the size uniform, accelerate the degradation rate, and be more conducive to the release of the antifouling agent. In addition, talcum powder can also control the release of the antifouling agent, avoiding the occurrence of the phenomenon of explosive release of the antifouling agent in a short time. The biodegradable marine antifouling coating in the present invention still has an antifouling effect for more than three months.

[0014] In another preferred embodiment, the organic solvent is dichloromethane. First, polycaprolactone is easily soluble in organic solvents, and dichloromethane has excellent solubility and can effectively dissolve relevant resin and polymer components. Second, since it is applied in the marine environment, it is necessary not to cause harm to marine organisms, and dichloromethane has low toxicity and is relatively safe for operators during use. Dichloromethane is relatively stable at room temperature and is not easily reacted with most acids, alkalis and other substances, which is conducive to the smooth progress of the preparation.

[0015] In another preferred embodiment, the antifouling agent is 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one.

[0016] In another preferred embodiment, stirring is also included during the modification reaction, and the rotation speed of the stirring is 1000 rmp / min to 1200 rmp / min.

[0017] In another preferred embodiment, the mass-volume ratio of poly(ε-caprolactone) to dichloromethane is 5 - 10 g : 40 - 60 mL.

[0018] In another preferred embodiment, the time of the mixing reaction is 5 min to 20 min;

[0019] Stirring is also included during the mixing reaction, and the rotation speed of the stirring is 1000 rmp / min to 1200 rmp / min.

[0020] The second aspect of the present invention provides the biodegradable marine antifouling coating.

[0021] The third aspect of the present invention provides the application of the biodegradable marine antifouling coating in the preparation of ship antifouling coatings.

[0022] In another preferred embodiment, the ship antifouling coating is used to prevent fouling organisms in the ocean from attaching to the ship.

[0023] The fourth aspect of the present invention provides an application of the biodegradable marine antifouling coating in the preparation of ship anticorrosion coatings.

[0024] Compared with the prior art, the present invention has the following beneficial effects.

[0025] The present invention uses talcum powder as a nucleating agent for poly(ε-caprolactone), improving the degradation efficiency, crystallinity, and crystal size of poly(ε-caprolactone), reducing the spherulite size of poly(ε-caprolactone) to no more than 10 μm, with uniform size, accelerating the degradation rate, being more conducive to the release of antifouling agents, and talcum powder can control the release of antifouling agents, avoiding the occurrence of burst release of antifouling agents in a short time.

[0026] The biodegradable marine antifouling coating in the present invention is composed of poly(ε-caprolactone), talcum powder, and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one. After the coating is applied to a ship, the main chain breaks under the dual action of hydrolysis of ester bonds and enzymatic catalysis degradation in seawater, forming a dynamic self-renewing surface and slowly releasing the encapsulated antifouling agent. The antifouling component inhibits the formation of the first-stage film, cutting off the necessary nutrient components for the growth and development of fouling organisms from the source, achieving the effect of preventing fouling attachment. The addition of talcum powder can improve the mechanical properties and adhesion of the coating, improve the degradation performance of the coating and control the release of antifouling agents, ultimately achieving the dual effects of uniform degradation of the coating and controlled release of antifouling agents. Description of the Drawings

[0027] Figure 1 It is the thermogravimetric curve graph of different marine antifouling coatings.

[0028] Figure 2 It is the crystallization morphology graph of different marine antifouling coatings; among them, a is the crystallization morphology graph of PCL, b is the crystallization morphology graph of PCL and talcum powder, c is the crystallization morphology graph of PCL and DCOIT, and d is the crystallization morphology graph of PCL, talcum powder, and DCOIT.

[0029] Figure 3 It is the result graph of the weight loss ratio of the hydrolysis experiment of different marine antifouling coatings.

[0030] Figure 4 It is the schematic diagram of the self-made device for resisting seawater immersion and scouring in the laboratory.

[0031] Figure 5 It is the result graph of the adsorption force of different antifouling coatings.

[0032] Figure 6 It is the result graph of the surface contact angle of different antifouling coatings.

[0033] Figure 7 It is the surface morphology graph of different antifouling coatings before and after hydrolysis.

[0034] Figure 8 It is the result graph of the roughness of different antifouling coatings before and after hydrolysis.

[0035] Figure 9 The results of three - month submersion tests of samples with different components on the shallow - sea hanging board; in the figure, A represents the blank board; B represents PCL; C represents PCL / talc powder; D represents PCL - H - D10; E represents PCL - H - D15; F represents PCL - H - D20; G represents PCL - H - L10; H represents PCL - H - L15; I represents PCL - H - L20; 1, 2, and 3 represent the number of months of immersion in seawater. Specific implementation manners

[0036] The present invention will be described in detail below with reference to specific embodiments, but it should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well - known to those skilled in the art. The materials, reagents, etc. used in the following embodiments can be obtained from commercial sources unless otherwise specified.

[0037] The currently used polymer resins are either non - degradable or have a degradation rate that is difficult to control, resulting in the difficulty of uniform release of antifouling agents. Even for self - polishing antifouling polymers, their surface self - renewal depends to a large extent on the movement of the ship and the scouring of the surrounding seawater. It is very difficult to effectively coordinate the solubility after polymer hydrolysis, resulting in a decrease in the release rate of antifouling agents during the static stage and the inability to fully exert their efficacy. Moreover, non - degradable materials released into the ocean will cause serious marine plastic waste pollution.

[0038] Since the crystallization properties of the PCL substrate directly affect the degradation rate of PCL. Unmodified PCL is difficult to have good antifouling effects relying only on its own properties. In addition, the film - forming property of PCL is also poor and it is extremely easy to fall off from the substrate. The small molecules generated by PCL hydrolysis do not have sufficient antifouling toxicity, and antifouling agents need to be added to ensure the antifouling effect. If the compatibility between the antifouling agent and the resin is poor, it will lead to the rapid migration of the antifouling agent, thus affecting the stability of the antifouling agent release; when the addition amount of the antifouling agent is relatively high, it is difficult to ensure the dispersibility of the antifouling agent, which will lead to a decrease in the mechanical properties of the coating and the occurrence of local burst release of the antifouling agent. At the initial stage of the release of the antifouling agent, due to sufficient content and large density, burst release will occur. When the release rate is stable in the later stage, due to the lack of sufficient amount and concentration of the antifouling agent, the requirement for inhibiting biological fouling cannot be met, and the ideal antifouling effect cannot be achieved, greatly shortening the antifouling period. Moreover, most of the existing antifouling coatings on the market use toxic antifouling agents, which may affect human health and ecological safety through the food chain while achieving the purpose of killing the organisms attached to the surface.

[0039] The shallow - water aquaculture industry is an indispensable part of agriculture. Fouling organisms have an adverse impact on the growth of aquaculture objects, so a large amount of manpower and material resources are required to clean the equipment. During the peak season of aquaculture, the equipment, protective netting, etc. need to be replaced and cleaned every 10 to 15 days, which causes serious waste of resources and compression of economic profits. To reduce costs, some unscrupulous merchants choose to soak the equipment with highly toxic chemical agents for anti - fouling, which causes irreversible harm to food safety and the marine ecosystem. Therefore, various phenomena such as high costs and unstable timeliness restrict the application of anti - fouling coatings for aquaculture equipment.

[0040] The present invention prepares a biodegradable marine anti - fouling coating with a simple synthesis process, low cost and easy brushing, filling the gap of environmentally friendly anti - fouling coatings for shallow - sea aquaculture equipment. By using talcum powder as a nucleating agent, the present invention modifies poly(ε - caprolactone). After adding talcum powder, the degradation efficiency, crystallinity and crystal size of poly(ε - caprolactone) can be improved. The spherulite size of poly(ε - caprolactone) is reduced, and the size is uniform, and the degradation rate is accelerated, which is more conducive to the release of anti - fouling agents. In addition, talcum powder can also control the release of anti - fouling agents, avoiding the occurrence of burst release of anti - fouling agents in a short time.

[0041] In the following examples, polycaprolactone (PCL, Solvay, USA); talcum powder (Mg 3 Si 4 O 10 (OH) 2 , Guilin Guangxi Talc Development Co., Ltd.); 4,5 - dichloro - N - octyl - 4 - isothiazolin - 3 - one (DCOIT, Shandong Yousuo Chemical Technology Co., Ltd.); capsaicin (C 18 H 27 NO 3 , Jishui Yikang Natural Spice Oil Refinery); dichloromethane (CH 2 Cl 2 , Xilong Chemical Co., Ltd.).

[0042] The following specifically describes a biodegradable marine anti - fouling coating, its preparation method and application.

[0043] Example 1

[0044] A preparation method of a biodegradable marine anti - fouling coating includes the following steps:

[0045] S1. Heat the constant temperature water bath to 60 °C, adjust the mechanical stirrer to 1000 rmp, mix 40 mL of dichloromethane with 5 g of PCL. After all are dissolved to reach the molten state, add 0.52 g of talcum powder, and finish dropping the mixed talcum powder within 0.5 min. Keep the reaction temperature at 60 °C. During the reaction, if solidification occurs, dichloromethane can be added dropwise at any time to prevent thickening and solidification from affecting stirring and causing insufficient mixing. After sufficient mixing to reach the molten state, cool down to below 60 °C, remove dichloromethane, and obtain a polyester-based substrate.

[0046] S2. Heat the polyester-based substrate to the molten state, add 1.38 g of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one into the stirrer in small amounts and multiple times, adjust the stirring rate to 1000 rmp, and stir and react for 20 min. If the stirring is uneven or too thick during the stirring process, a small amount of dichloromethane solvent can be added to obtain a biodegradable marine antifouling coating.

[0047] Example 2

[0048] A preparation method of a biodegradable marine antifouling coating, comprising the following steps:

[0049] S1. Heat the constant temperature water bath to 70 °C, adjust the mechanical stirrer to 1200 rmp, mix 50 mL of dichloromethane with 7.5 g of PCL. After all are dissolved to reach the molten state, add 0.73 g of talcum powder, and finish dropping the mixed talcum powder within 0.5 min. Keep the reaction temperature at 70 °C. During the reaction, if solidification occurs, dichloromethane can be added dropwise at any time to prevent thickening and solidification from affecting stirring and causing insufficient mixing. After sufficient mixing to reach the molten state, cool down to below 60 °C, take out the polymer, and prepare a polyester-based substrate.

[0050] S2. Heat the polyester-based substrate to the molten state, add 1.45 g of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one into the stirrer in small amounts and multiple times, adjust the stirring rate to 1200 rmp, and stir and react for 5 min. If the stirring is uneven or too thick during the stirring process, a small amount of dichloromethane solvent can be added to obtain a biodegradable marine antifouling coating.

[0051] Example 3

[0052] A preparation method of a biodegradable marine antifouling coating, comprising the following steps:

[0053] S1. Heat the thermostatic water bath to 80 °C, adjust the mechanical stirrer to 1200 rmp, mix 60 mL of dichloromethane with 10 g of PCL. After complete dissolution to reach the molten state, add 0.9 g of talcum powder, and finish dropping the mixed talcum powder within 0.5 min. Keep the reaction temperature at 80 °C. During the reaction, if solidification occurs, dichloromethane can be added dropwise at any time to prevent thickening and solidification from affecting stirring and causing insufficient mixing. After sufficient mixing to reach the molten state, cool down to below 60 °C, take out the polymer to prepare a polyester-based substrate.

[0054] S2. Heat the polyester-based substrate to the molten state, add 1.21 g of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one into the stirrer in small portions, adjust the stirring rate to 1200 rmp, and stir and react for 10 min. During the stirring process, if the stirring is uneven or too thick, a small amount of dichloromethane solvent can be added to obtain a biodegradable marine antifouling coating.

[0055] Comparative Example 1:

[0056] A preparation method of a marine antifouling coating includes the following steps:

[0057] Heat the thermostatic water bath to 60 °C, adjust the mechanical stirrer to 1000 rmp, mix 40 mL of dichloromethane with 6.38 g of PCL. After complete dissolution to reach the molten state, add 0.52 g of talcum powder, and finish dropping the mixed talcum powder within 0.5 min. Keep the reaction temperature at 60 °C. During the reaction, if solidification occurs, dichloromethane can be added dropwise at any time to prevent thickening and solidification from affecting stirring and causing insufficient mixing. After sufficient mixing to reach the molten state, cool down to below 60 °C, remove dichloromethane to obtain a polyester-based substrate, denoted as PCL / talcum powder.

[0058] Comparative Example 2:

[0059] A preparation method of a marine antifouling coating includes the following steps:

[0060] Heat 5.25 g of PCL to the molten state, add 1.38 g of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one into the stirrer in small portions, adjust the stirring rate to 1000 rmp, and stir and react for 20 min. During the stirring process, if the stirring is uneven or too thick, a small amount of dichloromethane solvent can be added to obtain a marine antifouling coating, denoted as PCL / DCOIT.

[0061] To further illustrate the effects of the biodegradable marine antifouling coating in the present invention, the following experiments were conducted.

[0062] 1. Antifouling effects of different marine antifouling coatings

[0063] Taking PCL as a control, the thermal gravimetric analysis was carried out on the marine antifouling coatings obtained in Example 1, Comparative Example 1 and Comparative Example 2 respectively. The biodegradable marine antifouling coating in Example 1 was denoted as PCL / talc / DCOIT. The specific process is as follows:

[0064] Take 4 acrylic substrates of the same size. First, wipe the surface of the substrates clean with deionized water and lint-free paper, and then ultrasonically clean them in 75% alcohol solution for half an hour for later use. The different marine antifouling coatings were applied onto acrylic substrates with a size of 500×250 mm by drop coating method. Three parallel samples were prepared for each ratio, and the dry film thickness was controlled at (500±10) μm for thermal gravimetric analysis. The results are as Figure 1 and Table 1 show.

[0065] Table 1 TGA data of samples

[0066] Sample Name Feed Mass Ratio (wt%) Decomposition Temperature (°C) Residual Carbon Rate (%) PCL 100 420.68 0 PCL / Talc 92.5:7.5 365.71 5.98 PCL / DCOIT 80:20 401.94 2.81 PCL / Talc / DCOIT 72.5:7.5:20 383.03 10.78

[0067] From Figure 1 and the results in Table 1, it can be seen that the thermal decomposition temperature of PCL is about 420.68 °C. When the temperature rises to about 600 °C, the material has been completely burned out without residue. For PCL / DCOIT, since the added DCOIT is a small molecule and decomposes during thermal gravimetry, the thermal decomposition temperature of this composite material is about 401 °C. As a composite material of a ternary system, PCL / / DCOIT has a maximum residual carbon rate of 10.78%, but the thermal decomposition temperature is about 383.03 °C, which is the material that starts thermal decomposition first among these composite materials. The temperature range in the ocean is between -2 °C and 30 °C, which changes with ocean currents and seasons. Therefore, this antifouling coating has good thermal stability during actual application.

[0068] 2. Structural characterization

[0069] The crystallization morphologies of the different marine antifouling coatings in Table 1 were analyzed respectively. The results are as Figure 2 shown. From Figure 2 it can be seen that the spherulite size of PCL is relatively large, about 50 μm. Figure 2 Figure b in Figure 2 is the morphology diagram of PCL / talc. The spherulite size is significantly reduced, and all spherulite sizes are less than 10 μm. This further demonstrates that the addition of the nucleating agent effectively reduces the crystallization size of PCL. Figure 2 Figure c in Figure 2The crystal size of c has been significantly reduced and is similar to the effect presented by b of Figure 2 . By comparing a with b and c with d in Figure 2 , it is not difficult to see that the addition of the nucleating agent effectively reduces the crystal size of the material. This proves that even though the addition of DCOIT increases many irregular crystals, it does not interfere with the fact that talc acts as a modifier for the spherulite size of PCL.

[0070] 3. Analysis of Crystallization and Drying Properties

[0071] Analysis of Crystallization Properties

[0072] The crystallization properties of different marine antifouling coatings in Table 1 were analyzed respectively, and the results are as Figure 3 shown. The crystallization properties of the coating directly affect the degradation rate of the coating and the efficiency of self-renewal on the surface of the film layer. As Figure 3 can be seen, the sample with the fastest degradation rate at each time point is PCL / DCOIT. This is because in this composite system, not only PCL degrades, but DCOIT, as a small molecule crystalline substance, can also degrade and release. The degradation rate of the PCL / talc / DCOIT sample is lower than that of the PCL / DCOIT sample, indicating that the presence of the nucleating agent talc slows down the release of the antifouling agent DCOIT in seawater. The purpose of adding the antifouling agent is to release it along with the degradation of the substrate, and the presence of talc controls the release of the antifouling agent, avoiding the phenomenon of explosive release of the antifouling agent in a short time.

[0073] Analysis of Drying Properties

[0074] The crystallization properties of different marine antifouling coatings in Table 1 were analyzed respectively, and the amount of talc and DCOIT were adjusted respectively to obtain different samples. The specific addition amounts are shown in Table 2. The obtained samples were analyzed for drying properties, and the results are shown in Table 2. As can be seen from Table 2, the drying time of the pure PCL coating is much longer than that of the coating with the nucleating agent added. Therefore, adding fillers such as nucleating agents can reduce the drying time of the film layer. Comparing pure PCL and PCL / talc, it is found that the less the PCL content, the shorter the drying time. When a certain amount of nucleating agent is added, the more DCOIT content, the longer the drying time instead. It is speculated that the access of other chain segments changes the structure, crystallinity and other properties of polycaprolactone PCL, thus changing the drying time of the coating. Generally speaking, the biodegradable marine antifouling coatings in the present invention can all be dried within 24 hours, which meets the requirements of easy brushing and short construction period

[0075] Table 2 Drying Time Data of Different Samples

[0076] Sample Name Content of Each Element (wt%) Surface Drying Time (min) Through Drying Time (h) PCL 100 225 23 PCL / Talc-a 95 / 5 160 19.5 PCL / Talc-b 92.5 / 7.5 150 19 PCL / Talc-c 90 / 10 145 18.5 PCL / Talc / DCOIT-a 82.5 / 7.5 / 10 155 19 PCL / Talc / DCOIT-b 77.5 / 7.5 / 15 160 20 PCL / Talc / DCOIT-c 72.5 / 7.5 / 20 170 21

[0077] In order to further illustrate the performance of the biodegradable marine antifouling coating in seawater, the following experiments were conducted.

[0078] 1. Specimen preparation

[0079] Antifouling coatings were prepared according to the formulations in Table 3 with different configuration systems and different blending materials.

[0080] Table 3 Proportions of components of the antifouling coating

[0081]

[0082]

[0083] Note: P represents PCL, H represents talc powder, D represents DCOIT, and L represents capsaicin.

[0084] 2. Research methods for the performance of the biodegradable antifouling coating

[0085] 1) Coating adhesion strength test: The adhesion of each coating system was tested by the cross-cut tape test with a cross-cut knife referring to the national standard GB / T9286-1998.

[0086] 2) Contact angle test: After drying, the surface of the unhydrolyzed sample film was wiped clean with filter paper without dust. The water used for testing was ultrapure water with a single-drop volume of about 4 μL. The whole process of the water droplet falling was photographed by a high-frequency camera, and then the average value of the contact angle of the sample was calculated through a fitting equation. After the sample was immersed in natural seawater for 7 days, the average contact angle of the hydrolyzed sample was tested using the same method.

[0087] 3) Surface morphology and roughness test: The surface morphology and roughness of the coating before and after hydrolysis were observed by a 3D optical profilometer of the RTEC up-sigma type.

[0088] 4) Antifouling performance test

[0089] Referring to the test method of the national standard GB / T5370-2007 "Test Method for Submerged Exposure of Antifouling Paint Panels in Shallow Sea", a shallow sea static panel test was carried out in the sea area near Xingshutun Port, Jinzhou District, Dalian (39°26’N, 122°21’E) to test the antifouling ability of the antifouling coating.

[0090] 3. Results

[0091] 1) Influence of the antifouling agent on the adsorption force of the coating surface

[0092] The antifouling coating samples shown in Table 3 were placed in a self-made device in the laboratory and continuously soaked and flushed for 30 days, and fresh seawater was replaced every 10 days. As Figure 4As shown. Then, according to the adhesion strength test method, the adhesion of different film layers of the samples before and after immersion and scouring was tested by the cross-cut method with a grid cutter. The results are as Figure 5 shown.

[0093] Comparison of anti-fouling coatings containing DCOIT and capsaicin before and after immersion and scouring Figure 5 It can be clearly seen that: for the anti-fouling coating containing DCOIT, the adhesion is still very strong after immersion and scouring, there is no peeling after cross-cutting, and the film layer remains intact; for the anti-fouling coating containing capsaicin, serious peeling occurs after immersion and scouring. When the addition ratio of capsaicin increases from 10wt% to 15wt%, slight damage appears on the film layer; when the addition ratio increases to 20wt%, the damage of the film layer becomes very serious. This shows that the adsorption force will decrease after adding capsaicin to the coating and the surface adsorption force decreases with the increase of capsaicin concentration, and the surface adsorption force of the coating added with DCOIT is better.

[0094] 2) Influence of anti-fouling agent on the static contact angle of the coating surface

[0095] As Figure 6 shown, the surface contact angles of P-H-D10, P-H-D15, and P-H-D20 are 101.205°, 100.75°, and 100.295° respectively, with almost no change. This shows that the surface contact angle has little relationship with the content of the added anti-fouling agent, and the hydrophobic state is consistent with the hydrophobic property of PCL. The contact angles of these samples have all shown a hydrophilic state of less than 90°.

[0096] 3) Influence of anti-fouling agent on the surface morphology and roughness of the coating

[0097] From Figure 7 and Figure 8It can be seen that the surface of the sample added with DCOIT is very rough before hydrolysis. As the content of the antifouling agent DCOIT increases, the surface roughness of the polymer gradually increases, and the surface morphology also becomes rough. The roughness of P-H-D10 before hydrolysis is about 1.78 μm, while the roughness of P-H-D15 before hydrolysis is about 2.27 μm, and the roughness of P-H-D20 before hydrolysis is about 3.40 μm. This is because DCOIT itself is also a small molecule crystalline organic compound, and crystallization has a great influence on its surface morphology and roughness. The surface morphology becomes smooth after hydrolysis, which is caused by the degradation of the coating. The samples added with capsaicin have a lower roughness before hydrolysis. As the content of the antifouling agent capsaicin increases, the surface roughness of the polymer becomes smaller and smaller. The roughness of P-H-L10 before hydrolysis is about 1.25 μm, the roughness of P-H-L15 before hydrolysis is about 1.07 μm, and the roughness of P-H-L20 before hydrolysis is about 0.71 μm. However, the surface morphology is relatively smooth. This is because capsaicin is dissolved and dispersed evenly in the organic solvent dichloromethane without generating large bubbles, and the flatness is relatively high and the porosity is relatively low during the natural drying process. The surface morphology becomes rougher and rougher after hydrolysis, but it is smaller than that of the DCOIT-containing samples with the same addition ratio. This is due to the poor mechanical properties of the samples caused by the properties of capsaicin-containing samples.

[0098] 4) Subsea panel test

[0099] Since the simulated marine scouring conditions in the laboratory are constant, but the actual marine environment is complex and changeable, and the effects of ocean currents, temperature changes, and the types and habits of fouling organisms are unpredictable, it is necessary to conduct subsea panel tests. It can be known from the literature that summer is the peak period for the reproduction of marine organisms, microorganisms, and algae, and there will be a large accumulation of fouling organisms. Therefore, a subsea panel experiment was carried out in Xingshutun, Jinzhou District, Dalian City (39°26’N, 122°21’E) in the Yellow Sea in June 2023.

[0100] Observation Figure 9 It can be seen that the samples A, B, and C without antifouling agents were fouled to varying degrees in the second month, and the surfaces of the samples were completely covered by the mucus layers of fouling organisms such as algae in the third month. For the samples D, E, and F added with DCOIT, the fouling degree was greatly reduced, and the antifouling ability was also greatly improved with the increase of the addition ratio, which is the performance of the nucleating agent and the antifouling agent cooperating with each other. For the samples G, H, and I added with capsaicin, the coating was damaged in the second month, and even the film was damaged in the first month with the increase of the addition ratio, indicating that capsaicin is not suitable as an antifouling agent for the PCL substrate. It can be seen that DCOIT is an antifouling agent suitable for the PCL / talc substrate, and the optimal addition concentration of DCOIT is 20 wt%.

[0101] From the above experiments, it can be seen that capsaicin, as an antifouling agent, will reduce the adsorption capacity of the substrate PCL. The samples containing capsaicin showed serious film peeling off in the shallow sea panel test, and the adhesion of the coating decreased with the increase of the capsaicin addition amount. This is due to the decrease in the mechanical properties of the material caused by the structural properties of capsaicin itself. The unique properties of capsaicin itself changed the hydrophobic properties of PCL. Because capsaicin has good compatibility with the solvent dichloromethane, in the surface morphology and roughness tests, the samples containing capsaicin showed lower roughness before immersion hydrolysis. In summary, the presence of capsaicin makes the mechanical properties of the composite coating decline, so capsaicin is not suitable for the PCL / talc powder substrate, and DCOIT is selected as the antifouling agent.

[0102] When DCOIT is used as an antifouling agent to synthesize and prepare an antifouling coating with the PCL / talc powder substrate, it has good coating mechanical properties and antifouling properties, can be well adsorbed on the sample plate, and meets the antifouling effect for more than three months.

[0103] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a biodegradable marine antifouling coating, characterized in that: The method comprises the following steps: mixing poly-ε-caprolactone and talcum powder at 60° C. to 80° C., carrying out a modification reaction in an organic solvent for 30 minutes to 60 minutes, using talcum powder to reduce the size of crystal spheres after crystallization of the poly-ε-caprolactone, and removing the organic solvent after the reaction is completed to obtain a polyester substrate; The polyester base is heated to a molten state, and an antifouling agent is added and mixed to react to obtain the biodegradable marine antifouling coating; The mass ratio of poly-ε-caprolactone, talc and antifouling agent is 72.5-82.5:7.5:10-20.

2. The method for preparing the biodegradable marine antifouling coating according to claim 1, characterized in that: The organic solvent is dichloromethane.

3. The method for preparing the biodegradable marine antifouling coating according to claim 1, characterized in that: The antifouling agent is 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.

4. The method for preparing the biodegradable marine antifouling coating according to claim 1, characterized in that: The modification reaction process also includes stirring, and the stirring speed is 1000 rpm to 1200 rpm.

5. The method for preparing the biodegradable marine antifouling coating according to claim 2, characterized in that: The mass volume ratio of poly-ε-caprolactone to dichloromethane is 5kg-10kg:40L-60L.

6. The method for preparing the biodegradable marine antifouling coating according to claim 1, characterized in that: The mixing reaction time is 5min to 20min; The mixing reaction process also includes stirring, and the stirring speed is 1000 rpm to 1200 rpm.

7. A biodegradable marine antifouling coating prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the biodegradable marine antifouling coating according to claim 7 in the preparation of ship antifouling coating.

9. Use of the biodegradable marine antifouling coating according to claim 7 in the preparation of ship anticorrosion coating.

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