Marine antifouling coating with main chain degradation and drag reduction functions and preparation method thereof

Abstract

The application relates to a marine antifouling paint with main chain degradation and drag reduction functions and a preparation method thereof, and relates to the technical field of marine antifouling paint. Compared with the current acrylate tin-free self-polishing paint, the surface renewal thereof depends on the scouring of strong water flow, and the static antifouling effect is not ideal; the prepared antifouling paint has excellent main chain degradation performance, and can exhibit excellent static antifouling effect; meanwhile, silicon oil can be continuously released to the coating surface in the degradation process, the surface energy of the coating surface is reduced, and the drag reduction effect is achieved. The operation method is simple, the cost is low, the application can be suitable for various sea areas, and the application has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of marine antifouling materials technology, and in particular to a marine antifouling coating with both main chain degradation and drag reduction functions, and its preparation method. Background Technology

[0002] Marine organisms attach themselves to equipment operating in the ocean, posing a significant threat to the modern marine economy.

[0003] Antifouling coatings are a widely adopted and cost-effective method for solving fouling and corrosion problems. Among them, silicone-based fouling-removing coatings and polyacrylate self-polishing coatings are currently the best-performing and most widely used marine antifouling coatings. However, the fouling-removing performance of silicone-based fouling-removing coatings depends on high water flow and cannot inhibit the attachment of marine organisms under static conditions. In addition, they also suffer from low mechanical strength and poor adhesion to the substrate. Polyacrylate self-polishing coatings are mainly based on self-polishing resins such as zinc polyacrylate, copper, or silane esters, and their antifouling effect can reach 3-5 years. However, the formulation design of this antifouling coating is mainly for large ships such as those engaged in ocean shipping, and its performance is subject to certain requirements on sailing time and speed. This is because existing self-polishing resin structures only contain hydrolyzable side groups, causing their surface self-renewal to rely on the scouring of strong water flow, resulting in unsatisfactory static antifouling capabilities. In addition, marine organism attachment can increase the drag of ships, and the global marine transport industry loses $150 billion annually due to marine biofouling, including an additional $30 billion in fuel consumption (energy consumption increases by about 10% due to biofouling). Therefore, the drag reduction performance of coatings is also of great significance.

[0004] Among the main-chain degradable polymeric antifouling coatings currently studied, common ones include polyesters such as polycaprolactone (PCL), polylactic acid (PLA), polybutylene succinate (PBS), and polybutylene adipate / terephthalate (PBAT). In seawater, these materials can form a constantly renewing dynamic surface through main-chain breakage, making it difficult for marine microorganisms to adhere. Simultaneously, the materials degrade into non-toxic small molecules, making them environmentally friendly antifouling materials. However, they also have drawbacks such as slow marine hydrolysis rates and difficulty in controlling the degradation rate. Taking polylactic acid as an example, whether PLA samples were placed in fresh water or ocean, no significant weight loss was observed after one year of immersion, and GPC testing showed no significant change in molecular weight. Other polyester plastics, such as PBAT and PBS, also showed a weight loss rate of less than 2% after one year of immersion in seawater, indicating very slow degradation. Polyglycolic acid, also known as polyhydroxyacetic acid, is polymerized from glycolic acid. Polyglycolic acid has a simple and regular linear molecular structure, making it the simplest linear aliphatic polyester. Due to its shortest repeating unit, it has the fastest hydrolysis rate among aliphatic polyesters. Similarly, polyglycolic acid copolymers also exhibit rapid hydrolysis, and their low molecular weight products are ideal hydrolysis initiators. For example, when polyglycolic acid samples are placed in the ocean, they essentially disappear after six months of immersion.

[0005] Therefore, there is a need for a marine antifouling coating that combines main-chain degradation and drag reduction, as well as its preparation method. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems by providing a marine antifouling coating and its preparation method that combine main-chain degradation and drag reduction functions. The antifouling resin obtained by this invention exhibits excellent main-chain degradation performance, demonstrating superior static antifouling effects. Simultaneously, during the degradation process, silicone oil is continuously released onto the coating surface, reducing the surface energy and thus achieving drag reduction. This invention is simple to operate, low in cost, applicable to various sea areas, and has broad application prospects. This antifouling coating exhibits excellent main-chain degradation performance, demonstrating superior static antifouling effects; simultaneously, during the degradation process, silicone oil is continuously released onto the coating surface, reducing the surface energy and thus achieving drag reduction.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The first objective of this invention is to provide a marine antifouling coating that combines main-chain degradation and drag reduction functions, the marine antifouling coating comprising the following components in weight percentage:

[0009]

[0010] More preferably, the marine antifouling coating with both main-chain degradation and drag reduction functions comprises the following weight percentages:

[0011]

[0012]

[0013] Preferably, the marine antifouling resin with both main-chain degradation and drag reduction functions has the following structure as shown in formula (I):

[0014]

[0015] Where m and n are integers;

[0016] The structure represented by R is shown in equation (II) below:

[0017]

[0018] Where x, y, and z are integers;

[0019] R1 indicates an alkyl group or aryl group with one or more carbon atoms;

[0020] R2 indicates an alkyl group or an aryl group with one or more carbon atoms;

[0021] R' indicates an alkyl group or aryl group with one or more carbon atoms;

[0022] R3 indicates an alkyl group with one or more carbon atoms;

[0023] R4 represents one of the following: methyl, hydroxyl, amino, or alcoholic hydroxyl groups.

[0024] Preferably, the marine antifouling resin with both main-chain degradation and drag reduction functions can be prepared by the following steps:

[0025] a) Under nitrogen protection, lactic acid, glycolic acid, polyacid, polyol compounds and catalyst are subjected to esterification and polycondensation reactions at 140-200℃. The top temperature of the fractionation column is controlled between 100-105℃. Most of the water by-product generated is removed by atmospheric pressure. Then, the temperature is maintained at 200-230℃ for 1-2 hours.

[0026] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess polyol compounds until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining polylactic acid glycol copolymer polyol; reaction time 4–12 h;

[0027] c) Add terminal hydroxyl silicone oil to the polylactic acid-glycolic acid copolymer polyol obtained in step b), continue stirring for 0.5–2 h, cool to 60–100 °C, and add an appropriate amount of solvent B to dissolve. After dissolution, add an appropriate amount of isocyanate compound dropwise at 60–100 °C. After the addition is complete, continue the reaction for 0.5–3 h to obtain a marine antifouling resin with both main chain degradation and drag reduction functions.

[0028] Preferably, the chemical reaction structure of step a) is as follows:

[0029]

[0030] Where R1 and R2 represent alkyl groups or aryl groups with 1 or more carbon atoms, and a, b, c, x, y, z, m, and n are integers.

[0031] For ease of representation,

[0032]

[0033] The following can be abbreviated as

[0034] HO-R-OH.

[0035] Preferably, the viscosity of the terminal alcohol hydroxyl silicone oil in step c) is between 100 and 10000 cs, and its structural formula is shown below:

[0036]

[0037] Where R represents an alkyl group having one or more carbon atoms.

[0038] R4 represents one of the following: methyl, hydroxyl, amino, or alcoholic hydroxyl groups.

[0039] Furthermore, ordinary hydroxyl silicone oil and polylactic acid glycol copolymer polyol have poor compatibility. Although blending the two can achieve the effect of continuously releasing silicone oil to the coating surface, the resulting coating has poor physical properties, is prone to delamination, and the release rate of silicone oil is difficult to control. In fact, by selecting terminal alcohol hydroxyl silicone oil, the terminal alcohol hydroxyl groups of the silicone oil can be crosslinked with polylactic acid glycol copolymer polyol through isocyanate groups, which increases the compatibility between the two and makes the release rate of silicone oil controllable.

[0040] Preferably, solvent B in step c) is one or more of toluene, xylene, ethyl acetate, butyl acetate, and methyl isobutyl ketone.

[0041] Preferably, the polyacid in step a) includes one or more of oxalic acid, terephthalic acid, succinic acid, and adipic acid.

[0042] Preferably, the polyol compound in step a) includes one or more of aliphatic polyol compounds and polyether polyols.

[0043] Preferably, the polyol compound specifically includes one or more of the following: ethylene glycol, propylene glycol, butanediol, pentanediol, neopentanediol, hexanediol, isohexanediol, trimethylolpropane, pentaerythritol, polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 800.

[0044] Preferably, the glycolic acid in step a) accounts for 10-80% of the total mass of all monomers (excluding the catalyst).

[0045] Preferably, the molecular weight of the polylactic acid glycol copolymer polyol is 1000 to 30000.

[0046] More preferably, the mass percentage of glycolic acid in step a) is 20-50%.

[0047] More preferably, the molecular weight of the polylactic acid glycol copolymer polyol is 2000 to 10000.

[0048] Furthermore, the degradation rate is related to the molecular weight of the polylactic acid-glycolic acid copolymer polyol; the larger the molecular weight, the slower the degradation rate. In addition, the degradation rate is related to the glycolic acid content in the marine antifouling resin, which has both main chain degradation and drag reduction functions; the higher the glycolic acid content, the faster the hydrolysis rate.

[0049] In fact, polyglycolic acid has a simple and regular linear molecular structure and is the simplest linear aliphatic polyester. Due to its shortest repeating unit, its ester group is not protected by other groups and is basically in a "naked" state, making it extremely susceptible to attack by water molecules. It has the fastest hydrolysis rate among aliphatic polyesters. Similarly, polylactic acid-glycolic acid copolymer also has a very fast hydrolysis rate. The higher the glycolic acid content, the faster the hydrolysis rate. However, when the glycolic acid content is too high, it will increase the crystallinity of polylactic acid-glycolic acid copolymer, thereby reducing the solubility of antifouling resin and affecting the physical properties of antifouling coating.

[0050] Preferably, the catalyst in step a) comprises one or more of the following: stannous octoate, stannous chloride, tetrabutyl titanate, zinc acetate, antimony acetate, antimony trioxide, and antimony glycolate.

[0051] Preferably, the amount of catalyst used in step a) is 0.01 to 2 wt% of the mass of glycolic acid.

[0052] Preferably, the isocyanate compound in step c) is one or more of the following: toluene diisocyanate and trimethylolpropane adduct (TDI-TMP), hexamethylene diisocyanate trimer (HDI trimer), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and toluene diisocyanate dimer (TDI dimer); hereinafter, it can be simply referred to as...

[0053] OCN-R′-NCO,

[0054] R' represents alkyl groups, aryl groups, etc., with 1 or more carbon atoms.

[0055] Preferably, the chemical reaction structure in step c) is as follows:

[0056]

[0057] Where x, y, z, m, and n are integers.

[0058] Preferably, the other resins include one or more of the following: rosin, hydrogenated rosin, rosin glycerol ester, self-polishing acrylate resin, and polyurethane resin.

[0059] More preferably, the other resins include one or more of rosin, hydrogenated rosin, and rosin glycerol esters.

[0060] Furthermore, the other resins must have good compatibility with marine antifouling resins that have both main-chain degradation and drag reduction functions; the combination of the two can adjust the physical properties and degradation rate of the coating, thus making it suitable for different sea areas.

[0061] Preferably, the organic antifouling agent includes one or more of copper pyrithione, zinc mancozeb, and (4,5-dichloro-N-octyl-4-isothiazolin-3-one)isothiazolinone derivatives.

[0062] Preferably, the pigments and fillers include one or more of the following: nano-silica, polytetrafluoroethylene, zinc oxide, calcium carbonate, talc, diatomaceous earth, mica powder, titanium dioxide, antimony oxide, barium sulfate, and iron oxide red.

[0063] Furthermore, pigments and fillers are important auxiliary materials in the preparation of marine antifouling coatings. They can give the coatings different colors, have a certain hiding power, and effectively improve the consistency of the antifouling coating, as well as the durability, weather resistance, heat resistance and mechanical strength of the coating film.

[0064] Preferably, the thixotropic agent includes one or more of organobentonite, fumed silica, cellulose ethers, and polyamide waxes.

[0065] Furthermore, the addition of thixotropic agents can increase the viscosity of marine antifouling coatings, prevent sagging during application, and prevent stratification during storage, thereby improving the storage stability of the coatings.

[0066] Preferably, solvent A is one or more of toluene, xylene, ethyl acetate, butyl acetate, and methyl isobutyl ketone.

[0067] A second objective of this invention is to provide a method for preparing the marine antifouling coating that combines main-chain degradation and drag reduction functions. The marine antifouling coating that combines main-chain degradation and drag reduction functions can be obtained by the following method:

[0068] (1) According to the above proportions, first place solvent A in a disperser and stir at a speed of 500-1000 r / min. Then add the marine antifouling resin with main chain degradation and drag reduction functions and the other resins until the resin is completely dissolved.

[0069] (2) Add thixotropic agent, continue stirring for 10-20 min, and then add cuprous oxide, pigments and fillers and organic antifouling agent in the order from liquid to powder and from small to large specific gravity. Continue to disperse at a speed of 2000-3000 r / min for 30-60 min to obtain the marine antifouling coating with main chain degradation and drag reduction functions.

[0070] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects:

[0071] (1) The marine antifouling coating of this technical solution has both main chain degradation and drag reduction functions. It has main chain degradation function: According to the design of molecular structure, a series of marine antifouling resins with both main chain degradation and drag reduction functions can be prepared. These resins have excellent main chain degradation performance, do not require external water flow rinsing, and have excellent antifouling effect even in a static state.

[0072] (2) The marine antifouling resin developed in this technical solution, which combines main chain degradation and drag reduction functions, will continuously release silicone oil to the coating surface during the degradation process, reduce the surface energy of the coating surface, increase the difficulty of marine organisms to attach, and thus achieve the drag reduction effect.

[0073] (3) The marine antifouling coating developed in this technical solution has both main chain degradation and drag reduction functions, and has high strength and adhesion, and excellent physical properties.

[0074] (4) The marine antifouling resin developed in this technical solution, which combines main chain degradation and drag reduction functions, can be biodegraded in the ocean, reducing the generation of marine microplastics. It is an environmentally friendly antifouling resin. At the same time, the resin can also be used in combination with other resins, thereby overcoming the limitation of weak static antifouling ability of existing self-polishing technology.

[0075] (5) The marine antifouling resin developed in this technical solution, which combines main chain degradation and drag reduction functions, has abundant raw material sources, simple production process, and affordable price, and is easy to carry out industrial production.

[0076] In summary, the marine antifouling coating provided by this invention, which combines main-chain degradation and drag reduction functions, can effectively prevent fouling even in a static state. Simultaneously, during the degradation process, the coating continuously releases silicone oil to its surface, reducing surface energy and increasing the difficulty for marine organisms to adhere, thereby achieving drag reduction. More importantly, this invention is simple to operate, low in cost, suitable for industrial production, has broad application prospects, and can generate significant social benefits.

[0077] Compared to existing acrylic self-polishing coatings, which generally only contain hydrolyzable side groups and whose surface renewal relies on strong water flow, resulting in unsatisfactory static antifouling performance, the antifouling resin prepared in this invention exhibits excellent main-chain degradation properties, demonstrating superior static antifouling effects. Simultaneously, during degradation, it continuously releases silicone oil to the coating surface, reducing the surface energy and thus achieving drag reduction. This invention is simple to operate, low in cost, applicable to various marine environments, and has broad application prospects. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of shallow sea immersion experiments for Examples 1, 2, 3, 4, 5, and 6, Comparative Example 1, and Comparative Example 2 (from left to right). Detailed Implementation

[0079] The present invention will now be described in detail with reference to specific embodiments, but this is by no means a limitation thereof. Any preparation methods, materials, structures, or compositional ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0080] This invention provides a marine antifouling coating that combines main-chain degradation and drag reduction functions, comprising the following weight percentages:

[0081]

[0082] More preferably, the marine antifouling coating with both main-chain degradation and drag reduction functions comprises the following weight percentages:

[0083]

[0084] This application provides a marine antifouling coating that combines main-chain degradation and drag reduction functions. The degradation rate is related to the molecular weight of the polylactic acid-glycolic acid copolymer polyol; the larger the molecular weight, the slower the degradation rate. In addition, the degradation rate is related to the glycolic acid content in the marine antifouling resin that combines main-chain degradation and drag reduction functions; the higher the glycolic acid content, the faster the hydrolysis rate.

[0085] In fact, polyglycolic acid has a simple and regular linear molecular structure and is the simplest linear aliphatic polyester. Due to its shortest repeating unit, its ester group is not protected by other groups and is basically in a "naked" state, making it extremely susceptible to attack by water molecules. It has the fastest hydrolysis rate among aliphatic polyesters. Similarly, polylactic acid-glycolic acid copolymer also has a very fast hydrolysis rate. The higher the glycolic acid content, the faster the hydrolysis rate. However, when the glycolic acid content is too high, it will increase the crystallinity of polylactic acid-glycolic acid copolymer, thereby reducing the solubility of antifouling resin and affecting the physical properties of antifouling coating.

[0086] Ordinary hydroxyl silicone oils and polylactic acid glycol copolymer polyols have poor compatibility. Although blending the two can achieve the effect of continuously releasing silicone oil to the coating surface, the resulting coating has poor physical properties, is prone to delamination, and the release rate of silicone oil is difficult to control. In fact, by using terminal alcohol hydroxyl silicone oils, the terminal alcohol hydroxyl groups of the silicone oil can be cross-linked with polylactic acid glycol copolymer polyols through isocyanate groups, which increases the compatibility between the two and makes the release rate of silicone oil controllable.

[0087] The other resins mentioned need to have good compatibility with marine antifouling resins that have both main chain degradation and drag reduction functions; when used in combination, the physical properties and degradation rate of the coating can be adjusted, thus making it suitable for different sea areas.

[0088] Pigments and fillers are important auxiliary materials in the preparation of marine antifouling coatings. They can give the coatings different colors, have a certain hiding power, and effectively improve the consistency of the antifouling coating, as well as the durability, weather resistance, heat resistance and mechanical strength of the coating film.

[0089] Adding thixotropic agents can increase the viscosity of marine antifouling coatings, prevent sagging during application, and prevent stratification during storage, thus improving the storage stability of the coatings.

[0090] Cuprous oxide is a stain repellent, but it is expensive. If it can achieve the desired effect without being used, costs can be saved.

[0091] In the following embodiments:

[0092] The method for determining the acid value is as follows: Weigh 1-3g of polymer polyol and place it in a three-necked flask. Add 20-30mL of toluene-ethanol (2:1) mixed solution, shake the flask to completely dissolve the sample, and heat if necessary. Add 1% phenolphthalein indicator dropwise, and titrate with 0.1mol / L standard KOH solution until a faint red color appears and does not fade within 30s as the endpoint. Perform a blank test using the same method.

[0093]

[0094] In the formula:

[0095] V 试验 —The volume of standard KOH solution consumed in the experiment, in mL;

[0096] V 空白 —The volume of standard KOH solution consumed in the blank, in mL;

[0097] C—Molar concentration of KOH standard solution, mol / L;

[0098] W—Sample mass, g;

[0099] 56.10 — Molar mass of potassium hydroxide, g / mol.

[0100] The surface energy testing method is as follows: the contact angle method in ISO 8296 standard is used for testing.

[0101] This invention does not impose any special restrictions on the raw materials used above, and any commercially available raw materials can be used. Specifically, the terminal alcohol hydroxyl silicone oil was purchased from Anhui Aiyota Silicone Oil Co., Ltd.; the rosin resin was purchased from Hubei Heifema Chemical Technology Co., Ltd.; and the fumed silica was purchased from Evonik Degussa.

[0102] To further illustrate the present invention, the present invention will be further described below with reference to specific embodiments.

[0103] The experimental methods described in the following embodiments of the present invention, unless otherwise specified, are generally performed under conventional conditions.

[0104] Example 1

[0105] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0106] Preparation of polylactic acid-glycolic acid copolymer polyol:

[0107] a) 71.6 g (0.7 mol) of 88% lactic acid, 38 g (0.3 mol) of 60% glycolic acid, 35.4 g (0.3 mol) of succinic acid, 36 g (0.35 mol) of 1,4-butanediol and 0.2 g of tetrabutyl titanate were added to the reactor. The oil bath temperature was raised to 180°C, and the temperature at the top of the fractionation column was maintained at 100–105°C for 3 h. Then the reaction was kept at 200°C for 1 h.

[0108] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess ethylene glycol until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining a waxy polylactic acid glycol copolymer polyol.

[0109] c) Add 5g of terminal hydroxyl silicone oil to the polylactic acid-glycolic acid copolymer polyol obtained in step b), stir for 1 hour, cool to 80°C, and add 10g of butyl acetate and 10g of xylene to dissolve. Then add 2g of toluene diisocyanate dropwise. After titration, continue the reaction for 1 hour to obtain a marine antifouling resin (solid content 80±2%) with both main chain degradation and drag reduction functions.

[0110] Prepare marine antifouling coatings according to the following weight ratios:

[0111] Includes: 20g marine antifouling resin with main chain degradation and drag reduction functions, 5g rosin resin, 25g cuprous oxide, 3g organic antifouling agent, 26g pigments and fillers, 1g thixotropic agent - organic bentonite, and 20g solvent.

[0112] The organic antifouling agent (3g) is copper pyridinethione; the pigments and fillers (26g) specifically include 5g of iron oxide red, 5g of zinc oxide, and 16g of talc; and the solvent (20g) is butyl acetate.

[0113] The marine antifouling coating with both main-chain degradation and drag reduction functions is prepared by the following method:

[0114] (1) According to the above ratio, first place the butyl acetate solvent in a disperser, and add the marine antifouling resin and the other resins with main chain degradation and drag reduction functions at a speed of 1000 r / min until the resin is completely dissolved.

[0115] (2) Add thixotropic agent, continue stirring for 20 min, then add organic antifouling agent, cuprous oxide, zinc oxide, talc and iron oxide red in sequence, and continue to disperse at 3000 r / min for 60 min to obtain marine antifouling coating with main chain degradation and drag reduction functions.

[0116] Example 2:

[0117] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0118] The preparation of polylactic acid-glycolic acid copolymer polyol is the same as in Example 1.

[0119] Prepare marine antifouling coatings according to the following weight ratios (cuprous oxide-free):

[0120] Includes: 20g of marine antifouling resin with main chain degradation and drag reduction functions, 5g of rosin resin, 10g of organic antifouling agent, 44g of pigments and fillers, 1g of thixotropic agent - organic bentonite and 20g of solvent.

[0121] The organic antifouling agent (10g) is a derivative of (4,5-dichloro-N-octyl-4-isothiazolin-3-one)isothiazolinone; the pigments and fillers (44g) specifically include 10g of iron oxide red, 10g of zinc oxide, and 24g of barium sulfate; and the solvent (20g) is butyl acetate.

[0122] The preparation of marine antifouling coatings with both main chain degradation and drag reduction functions is the same as in Example 1.

[0123] Example 3:

[0124] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0125] Preparation of polylactic acid-glycolic acid copolymer polyol:

[0126] a) 61.4 g (0.6 mol) of 88% lactic acid, 50.7 g (0.3 mol) of 60% glycolic acid, 10.4 g (0.1 mol) of malonic acid, 14.4 g (0.16 mol) of 1,4-butanediol and 0.4 g of stannous octoate were added to the reactor. The oil bath temperature was raised to 190 °C, and the temperature at the top of the fractionation column was maintained at 100–105 °C for 4 h. Then the reaction was maintained at 210 °C for 2 h.

[0127] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess ethylene glycol until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining a waxy polylactic acid glycol copolymer polyol.

[0128] c) Add 8g of terminal alcohol hydroxyl silicone oil, stir for 1 hour, cool to 70°C, add 15g of butyl acetate and 5g of xylene to dissolve, then add 3g of hexamethylene diisocyanate (HDI) dropwise. After titration, continue the reaction for 2 hours to obtain a marine antifouling resin with both main chain degradation and drag reduction functions (solid content 82±2%).

[0129] Prepare marine antifouling coatings according to the following weight ratios:

[0130] It includes: 25g of marine antifouling resin with main chain degradation and drag reduction functions, 2g of rosin glycerol ester resin, 25g of cuprous oxide, 4g of organic antifouling agent, 23g of pigments and fillers, 1g of thixotropic agent-fumed silica and 20g of solvent.

[0131] The organic antifouling agent is copper pyridinethione (4g); the pigments and fillers are 26g, specifically including 5g of iron oxide red, 10g of zinc oxide, and 8g of talc; and the solvent is butyl acetate (20g).

[0132] The preparation of marine antifouling coatings with both main chain degradation and drag reduction functions is the same as in Example 1.

[0133] Example 4:

[0134] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0135] The preparation of polylactic acid-glycolic acid copolymer polyol is the same as in Example 3.

[0136] Prepare marine antifouling coatings according to the following weight ratios (cuprous oxide-free):

[0137] It includes: 25g of marine antifouling resin with main chain degradation and drag reduction functions, 2g of rosin glycerol ester resin, 12g of organic antifouling agent, 40g of pigments and fillers, 1g of thixotropic agent-fumed silica and 20g of solvent.

[0138] The organic antifouling agent (12g) is an isothiazolinone derivative (4,5-dichloro-N-octyl-4-isothiazolin-3-one); the pigments and fillers (44g) specifically include 10g of iron oxide red, 10g of zinc oxide, and 20g of barium sulfate; and the solvent (20g) is ethyl acetate.

[0139] The preparation of marine antifouling coatings with both main chain degradation and drag reduction functions is the same as in Example 1.

[0140] Example 5:

[0141] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0142] Preparation of polylactic acid-glycolic acid copolymer polyol:

[0143] a) Add 61.4 g (0.6 mol) of 88% lactic acid, 50.7 g (0.3 mol) of 60% glycolic acid, 5.2 g (0.05 mol) of neopentyl glycol and 0.6 g of zinc acetate to the reactor, heat the oil bath to 185°C, maintain the top temperature of the fractionation column at 100–105°C, and react for 3 h; then keep at 220°C for 2 h.

[0144] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess ethylene glycol until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining a waxy polylactic acid glycol copolymer polyol.

[0145] c) Add 6g of terminal alcohol hydroxyl silicone oil, stir for 1 hour, cool to 70°C, add 10g of butyl acetate and 5g of xylene to dissolve, then add 4g of isophorone diisocyanate (IPDI) dropwise. After titration, continue the reaction for 2 hours to obtain a marine antifouling resin with both main chain degradation and drag reduction functions (solid content 82±2%).

[0146] Prepare marine antifouling coatings according to the following weight ratios:

[0147] It includes: 22g of marine antifouling resin with main chain degradation and drag reduction functions, 4g of hydrogenated rosin resin, 25g of cuprous oxide, 4g of organic antifouling agent, 24g of pigments and fillers, 1g of thixotropic agent-fumed silica and 20g of solvent.

[0148] The organic antifouling agent is copper pyridinethione (4g); the pigments and fillers are 24g, specifically including 5g of iron oxide red, 10g of zinc oxide and 9g of talc; and the solvent is butyl acetate (20g).

[0149] The preparation of marine antifouling coatings with both main chain degradation and drag reduction functions is the same as in Example 1.

[0150] Example 6:

[0151] This embodiment provides a marine antifouling coating that combines main chain degradation and drag reduction functions.

[0152] The preparation of polylactic acid-glycolic acid copolymer polyol is the same as in Example 5.

[0153] Prepare marine antifouling coatings according to the following weight ratios (cuprous oxide-free):

[0154] It includes: 22g of marine antifouling resin with main chain degradation and drag reduction functions, 4g of hydrogenated rosin resin, 12g of organic antifouling agent, 41g of pigments and fillers, 1g of thixotropic agent-fumed silica and 20g of solvent.

[0155] The organic antifouling agent (12g) is an isothiazolinone derivative (4,5-dichloro-N-octyl-4-isothiazolin-3-one); the pigments and fillers (41g) specifically include 10g of iron oxide red, 10g of zinc oxide, and 21g of barium sulfate; the solvent (20g) includes 10g of ethyl acetate and 10g of butyl acetate.

[0156] The preparation of marine antifouling coatings with both main chain degradation and drag reduction functions is the same as in Example 1.

[0157] Comparative Example 1:

[0158] This comparative example provides a marine antifouling coating.

[0159] Preparation of polylactic acid polyols:

[0160] a) Add 71.6 g (0.7 mol) of lactic acid with a mass concentration of 88%, 36 g (0.35 mol) of 1,4-butanediol and 0.2 g of stannous octoate to the reactor, heat the oil bath to 180 °C, maintain the top temperature of the fractionation column at 100–105 °C, and react for 3 h; then keep at 200 °C for 1 h.

[0161] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess ethylene glycol until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining waxy polylactic acid polyol.

[0162] c) Add 5g of terminal hydroxyl silicone oil to the polylactic acid polyol obtained in step b), stir for 1 hour, cool to 80°C, and add 10g of butyl acetate and 8g of xylene to dissolve. Then add 2g of toluene diisocyanate dropwise. After titration, continue the reaction for 1 hour to obtain a marine antifouling resin (solid content 80±2%) that has both main chain degradation and drag reduction functions.

[0163] Prepare marine antifouling coatings according to the following weight ratios:

[0164] It includes: 22g of marine antifouling resin with main chain degradation and drag reduction functions, 4g of rosin resin, 25g of cuprous oxide, 3g of organic antifouling agent, 25g of pigments and fillers, 1g of thixotropic agent-organic bentonite, and 20g of solvent.

[0165] The organic antifouling agent (3g) is copper pyridinethione; the pigments and fillers (25g) specifically include 5g of iron oxide red, 5g of zinc oxide, and 15g of talc; and the solvent (20g) is butyl acetate.

[0166] The preparation of the marine antifouling coating is the same as in Example 1.

[0167] Comparative Example 2

[0168] This comparative example provides a marine antifouling coating.

[0169] Preparation of polylactic acid-glycolic acid copolymer polyol:

[0170] a) 61.4 g (0.6 mol) of 88% lactic acid, 50.7 g (0.3 mol) of 60% glycolic acid, 10.4 g (0.1 mol) of malonic acid, 14.4 g (0.16 mol) of 1,4-butanediol and 0.4 g of stannous octoate were added to the reactor. The oil bath temperature was raised to 190 °C, and the temperature at the top of the fractionation column was maintained at 100–105 °C for 4 h. Then the reaction was maintained at 210 °C for 2 h.

[0171] b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess ethylene glycol until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining a waxy polylactic acid glycol copolymer polyol.

[0172] c) Add 15g of butyl acetate and 5g of xylene to dissolve, and obtain a main-chain degradable marine antifouling resin (solid content 80±2%).

[0173] Prepare marine antifouling coatings according to the following weight ratios:

[0174] It includes: 22g main-chain degradable marine antifouling resin, 5g rosin glycerol ester resin, 25g cuprous oxide, 4g organic antifouling agent, 23g pigments and fillers, 1g thixotropic agent-fumed silica and 20g solvent.

[0175] The organic antifouling agent is copper pyridinethione; the pigments and fillers are 26g, specifically including 5g of iron oxide red, 8g of zinc oxide and 10g of talc; and the solvent is 20g of butyl acetate.

[0176] The preparation of the marine antifouling coating is the same as in Example 1.

[0177] Long-term, firm adhesion to the substrate surface is a prerequisite for the antifouling effect of marine antifouling coatings. Therefore, coating adhesion strength is one of the important indicators for evaluating the quality of marine antifouling coatings. The antifouling coating prepared in this invention, due to the addition of some silicone oil, may have a certain impact on the coating's adhesion. The adhesion strength of eight marine antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-2 was tested according to GB / T 1720-2020 standard. The substrate was a Mark iron sheet coated with an epoxy zinc-rich primer. As shown in Table 1, the adhesion strength of the antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-2 all exceeded 1 MPa, fully meeting the requirements for the use of marine antifouling coatings.

[0178] Table 1. Adhesion of the coating.

[0179] Adhesion strength (MPa) Example 1 1.3±0.1 Example 2 1.4±0.1 Example 3 1.2±0.1 Example 4 1.3±0.1 Example 5 1.7±0.1 Example 6 1.7±0.1 Comparative Example 1 1.3±0.1 Comparative Example 2 2.2±0.1

[0180] Surface energy is a crucial factor affecting the drag reduction performance of marine antifouling coatings. Low surface energy can prevent the initial attachment of marine organisms and reduce drag generated during ship navigation, thus achieving a drag reduction effect. Studies have shown a correlation between surface energy and contact angle between liquids and solids; the larger the contact angle, the lower the surface energy, and vice versa. The surface energy of eight marine antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-2 was tested according to the contact angle method in ISO 8296. As shown in Table 2, the surface energies of the antifouling coatings prepared in Examples 1-6 and Comparative Example 1 were all below 27 mJ / m². 2It exhibits low surface energy characteristics, which can reduce drag. In Examples 3 and 4, the silicone oil content is relatively high, resulting in lower surface energy. In contrast, Comparative Example 2, which did not contain any alcohol-hydroxyl silicone oil component, produced a self-polishing antifouling coating with a surface energy of 30 mJ / m². 2 The above methods are unlikely to achieve the desired drag reduction effect.

[0181] Table 2. Surface energy of the coating.

[0182] <![CDATA[Surface energy (mJ / m 2 )]]> Example 1 26.6±0.1 Example 2 26.2±0.1 Example 3 24.2±0.1 Example 4 23.8±0.1 Example 5 25.5±0.1 Example 6 25.3±0.1 Comparative Example 1 26.3±0.1 Comparative Example 2 30.6±0.1

[0183] The marine antifouling coatings prepared in Examples 1-6 and Comparative Examples 1-2 were subjected to shallow sea immersion tests according to the national standard GB / T5370-2007 "Antifouling Paint Sample Shallow Sea Immersion Test Method". The test site was the Xiamen 725 Institute's panel base, and the test period was from May 5, 2022 to July 25, 2023. The results are as follows. Figure 1 As shown, from left to right, they are Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Comparative Example 1, and Comparative Example 2. The results are as follows: Figure 1 As shown, after one year of shallow sea immersion experiments, the surfaces of samples in Examples 1-6 remained smooth with virtually no marine organisms adhering to them, demonstrating excellent antifouling performance. In Comparative Example 1, due to the absence of glycolic acid monomer to regulate resin degradation rate, slight marine organisms had already adhered to the coating surface after one year. In Comparative Example 2, due to the absence of hydroxyl silicone oil components, although no marine organisms adhered to the coating surface after one year, the coating surface had become somewhat rough. This invention features a simple operation method, low cost, and suitability for industrial production, showing broad application prospects.

[0184] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A marine antifouling coating with both main-chain degradation and drag reduction functions, characterized in that, The marine antifouling coating comprises the following components in weight percentage: Marine antifouling resins with both main-chain degradation and drag reduction functions: 5-40% Other resins: 0-10% Cuprous oxide 0~40%, Organic antifouling agent 0~10%, Pigments and fillers 2-40%, Thixotropic agent 0~3%, Solvent A 10~40%; The structure of the marine antifouling resin, which combines main-chain degradation and drag reduction functions, is shown in formula (I): (I)； Where m and n are integers; The structure represented by R is shown in equation (II) below: (II); Where x, y, and z are integers; R1 indicates an alkyl group or aryl group with one or more carbon atoms; R2 indicates an alkyl group or an aryl group with one or more carbon atoms; R' indicates an alkyl group or aryl group with one or more carbon atoms; R3 indicates an alkyl group with one or more carbon atoms; R4 represents one of the following: methyl, hydroxyl, amino, or alcoholic hydroxyl groups.

2. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, The preparation method of the marine antifouling resin with both main-chain degradation and drag reduction functions includes the following steps: a) Under nitrogen protection, lactic acid, glycolic acid, polyacid, polyol compounds and catalyst are subjected to esterification and polycondensation reactions. The water by-product generated is removed by evaporation at atmospheric pressure, followed by heat preservation. b) Evacuate the vacuum and gradually increase the vacuum level to remove trace amounts of water and excess polyol compounds until the acid value of the synthesized product is lower than 5 mg KOH / g, thus obtaining polylactic acid glycol copolymer polyol. c) Add terminal hydroxyl silicone oil to the polylactic acid-glycolic acid copolymer polyol obtained in step b), continue stirring, cool down, add solvent B to dissolve, add isocyanate compound dropwise, and after the dropwise addition is complete, continue the reaction to obtain a marine antifouling resin with both main chain degradation and drag reduction functions.

3. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 2, characterized in that, The polyacids mentioned in step a) include one or more of oxalic acid, terephthalic acid, succinic acid, and adipic acid; The polyol compound mentioned in step a) includes one or more of aliphatic polyol compounds and polyether polyols; the glycolic acid mentioned in step a) accounts for 10-80% of the total mass of all monomers; The molecular weight of the polylactic acid glycol copolymer polyol is 1000~30000; The catalyst in step a) comprises one or more of the following: stannous octoate, stannous chloride, tetrabutyl titanate, zinc acetate, antimony acetate, antimony trioxide, and antimony glycolate. The amount of catalyst used in step a) is 0.01~2 wt% of the mass of glycolic acid; In step c), solvent B is one or more of toluene, xylene, ethyl acetate, butyl acetate, and methyl isobutyl ketone. The isocyanate compound mentioned in step c) is one or more of the following: toluene diisocyanate and trimethylolpropane adduct, hexamethylene diisocyanate trimer, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate dimer.

4. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, The other resins include one or more of the following: rosin, hydrogenated rosin, rosin glycerol ester, self-polishing acrylate resin, and polyurethane resin.

5. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, The organic antifouling agent includes one or more of copper pyrithione, zinc mancozeb, and (4,5-dichloro-N-octyl-4-isothiazolin-3-one)isothiazolinone derivatives.

6. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, The pigments and fillers include one or more of the following: nano-silica, polytetrafluoroethylene, zinc oxide, calcium carbonate, talc, diatomaceous earth, mica powder, titanium dioxide, antimony oxide, barium sulfate, and iron oxide red.

7. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, The thixotropic agent includes one or more of organobentonite, fumed silica, cellulose ethers, and polyamide waxes.

8. The marine antifouling coating with both main-chain degradation and drag reduction functions according to claim 1, characterized in that, Solvent A is one or more of toluene, xylene, ethyl acetate, butyl acetate, and methyl isobutyl ketone.

9. A method for preparing a marine antifouling coating with both main-chain degradation and drag reduction functions as described in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: (1) According to the ratio, first stir solvent A at a speed of 500-1000 r / min, then add marine antifouling resin and other resins that have both main chain degradation and drag reduction functions until the resin is completely dissolved; (2) Add thixotropic agent, continue stirring, then add cuprous oxide, pigments, fillers and organic antifouling agent, disperse at 2000~3000r / min for 30~60min to obtain the marine antifouling coating with main chain degradation and drag reduction functions.

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