Antifouling coating for nets and its use

Abstract

The application relates to the field of marine antifouling technology and discloses an antifouling paint for net clothes and application thereof. The antifouling paint comprises a film-forming resin; and the preparation method of the film-forming resin comprises the following steps: taking anhydride and 1,4-cyclohexane dimethanol as raw materials, and performing polycondensation reaction between anhydride groups and hydroxyl groups to prepare compound I; taking compound I, an anhydride-containing compound and / or a dibasic acid, and a dibasic alcohol as raw materials, and performing polycondensation reaction between anhydride groups and / or carboxyl groups and hydroxyl groups to prepare carboxyl-containing polymer II; and taking the carboxyl-containing polymer II and a compound containing at least two epoxy groups as raw materials, and performing ring-opening reaction between epoxy groups and carboxyl groups to prepare the film-forming resin. The film-forming resin in the antifouling paint is synthesized through a special method, has good hydrophilicity, flexibility and elasticity, can make the paint form a coating on the net clothes, and can play a good antifouling role and reduce the influence of the coating on the stretching capacity of the net clothes.

Description

Technical Field

[0001] The present invention relates to the technical field of marine antifouling, in particular to an antifouling coating for nets and application thereof. Background Art

[0002] With declining fishery resources, marine fisheries are shifting from capture fishing to aquaculture. The development of deep-sea aquaculture is a consensus among coastal countries. However, marine aquaculture inevitably faces the threat of the attachment of marine fouling organisms, which poses a significant threat. Fouled fishing nets, under the influence of currents, reduce the aquaculture capacity of the cages, compress the mesh area, and increase the weight of the cages, causing deformation. Fouling organisms also erode and damage the nets, significantly shortening the cage's lifespan. Fouling organisms growing on the surface of the nets reduce the mesh area, causing blockage and hindering convection between the inner and outer seawater. This hinders nutrient exchange, dissolved oxygen diffusion, and the removal of metabolic waste. This not only reduces aquatic product production but also easily leads to eutrophication, which is harmful to the environment. Complex biofouling communities that develop on the cage surface can indirectly trigger further sedimentation, breed bacteria and parasites, reduce aquatic product yields, and in severe cases, cause stunted growth or even death, severely impacting economic returns.

[0003] Currently, the marine aquaculture industry often uses physical removal, antifouling agents, and biological control methods to control biofouling. Physical removal methods typically use a variety of methods to address the problem of fishing net fouling, such as regular net changes, mechanical cleaning using antifouling or cage rotation designs, and chemical control agents. The process is cumbersome, labor-intensive, and time-consuming. The use of biological control technology to solve the problem of marine biofouling has huge potential market value, but the high cost limits its application in the marine aquaculture industry. The use of net antifouling coatings is the current mainstream antifouling method. Antifouling coatings are usually applied to fishing nets by dipping. Marine aquaculture requires that the antifouling effect of nets last for at least six months.

[0004] Patents CN202010384888.9, CN201910811485.5, and CN201911206394.5 use chloroether resin, modified polyethylene resin, and polyurethane resin as film-forming substances, respectively. Polyurethane resin has good flexibility, but is relatively expensive, unstable in storage, and prone to gelling. Chloroether resin and modified polyethylene resin are almost impossible to hydrolyze and polish, resulting in poor antifouling effects. Patent CN201210554914.3 uses zinc acrylate and acrylic silicone resin as film-forming substances. These coatings have poor flexibility and, after covering the net, significantly reduce their ability to expand and contract, affecting the normal operation of the net. Furthermore, due to the limited antifouling effect of film-forming substances, large amounts of copper antifouling agents are often added to net antifouling coatings on the market to achieve antifouling effectiveness. This does not meet environmental protection requirements and poses potential risks to aquatic life. Summary of the Invention

[0005] To address the technical problem of existing antifouling coatings for nets, which struggle to achieve both flexibility and antifouling effectiveness, the present invention provides an antifouling coating for nets. This coating utilizes a film-forming resin synthesized using a unique method, exhibiting excellent hydrophilicity, flexibility, and elasticity. This allows the coating to effectively exert its antifouling effect upon application to the net, while minimizing the coating's impact on the net's ability to expand and contract.

[0006] The specific technical solutions of the present invention are:

[0007] In a first aspect, the present invention provides an antifouling coating for nets, comprising a film-forming resin; and a method for preparing the film-forming resin comprises the following steps:

[0008] (1) Using acid anhydride and 1,4-cyclohexanedimethanol as raw materials, an esterification reaction between an acid anhydride group and a hydroxyl group is carried out to prepare compound I;

[0009] (2) using compound I, an anhydride-containing compound and / or a dibasic acid, and a diol as raw materials, to carry out a polycondensation reaction between an anhydride group and a carboxyl group and a hydroxyl group, or to carry out a polycondensation reaction between a carboxyl group and a hydroxyl group, to prepare a carboxyl-containing polymer II;

[0010] (3) Using a carboxyl-containing polymer II and a compound containing at least two epoxy groups as raw materials, a ring-opening reaction between the epoxy group and the carboxyl group is carried out to prepare a film-forming resin.

[0011] The film-forming resin synthesized by the above method contains numerous hydrophilic groups (including carboxyl, hydroxyl, and ester groups), which impart excellent hydrophilicity to the film-forming resin. After forming an antifouling coating on the net, the coating undergoes hydrolysis and self-polishing in seawater, thereby exerting a strong antifouling effect. Tests have shown that the antifouling coating of the present invention achieves excellent antifouling effectiveness without the need for the addition of a copper-based antifouling agent.

[0012] After synthesizing polymer 1, the present invention performs a first chain extension on the polymer using a compound containing anhydride and / or a dibasic acid and a diol, and then performs a second chain extension using a compound containing at least two epoxy groups. Through the two chain extensions, the obtained film-forming resin can have a higher molecular weight, thereby giving it better film-forming properties, and can also allow the film-forming resin to have a linear structure with a larger molecular weight. This structure can give the film-forming resin better flexibility and elasticity, thereby reducing the impact of the antifouling coating on the stretchability of the net, and also enhancing the quick-drying ability of the coating.

[0013] Preferably, step (1) comprises the following steps: using itaconic anhydride, 1,4-cyclohexanedimethanol and an initiator as raw materials, carrying out an esterification reaction between anhydride groups and hydroxyl groups, and carrying out an addition polymerization reaction of alkenyl groups to prepare compound I.

[0014] By using alkenyl-containing itaconic anhydride in step (1) and adding an initiator to cause the alkenyl to undergo an addition polymerization reaction, the film-forming resin can have a three-dimensional spatial network, giving the coating a better instantaneous thixotropic stabilization effect and making it exhibit better anti-sagging performance, thereby improving its one-time wetting and covering rate on the net.

[0015] Preferably, in step (3), the compound containing at least two epoxy groups is polyethylene glycol diglycidyl ether.

[0016] Polyethylene glycol diglycidyl ether has high hydrophilicity, which can make the antifouling coating have better self-polishing properties in seawater. At the same time, compared with epoxy macromolecular compounds containing multiple crosslinking groups, polyethylene glycol diglycidyl ether has a relatively low molecular weight and a structure with two epoxy groups, which can make the resulting film-forming resin have a relatively low crosslinking density, thereby increasing the abrasion rate of the film-forming resin in seawater. In addition, the relatively low degree of crosslinking can also make the film-forming resin contain more high-molecular-weight linear structures, which can make the film-forming resin have better flexibility and elasticity. Therefore, using polyethylene glycol diglycidyl ether to extend the chain of polymer II can greatly enhance the antifouling effect of the coating of the present invention and reduce its impact on the elasticity of the net.

[0017] Furthermore, the epoxy value of the polyethylene glycol diglycidyl ether is 0.35 to 0.80.

[0018] Preferably, in step (2), the anhydride-containing compound is hexahydrophthalic anhydride, and the dibasic acid is adipic acid.

[0019] Preferably, in step (2), the diol is one or both of neopentyl glycol and tetraethylene glycol.

[0020] Preferably, the specific process of step (1) includes the following steps: under the protection of inert gas, mixing itaconic anhydride, 1,4-cyclohexanedimethanol and solvent I, reacting at 60-70°C for 2.5-3.5 hours, then adding a portion of initiator, reacting at 85-95°C for 1-2 hours, and then adding the remaining initiator, and continuing to react at 85-95°C for 1-2 hours.

[0021] Furthermore, in step (1), the mass ratio of itaconic anhydride to initiator is 1:0.005-0.008.

[0022] Furthermore, in step (1), the mass ratio of the portion of initiator to the remaining initiator is 2.5 to 3.5:1.

[0023] Preferably, the specific process of step (2) includes the following steps: adding an anhydride-containing compound and / or a dibasic acid, a diol, a condensation reaction catalyst and a solvent II to the product obtained in step (1), reacting at 155-165° C. for 1-2 hours, then heating to 175-185° C. and continuing to react for 1-2 hours, then heating to 195-205° C. and continuing to react for 6-24 hours, and finally heating to 225-235° C. and maintaining for 30-40 minutes.

[0024] In the process of chain extension of compound I using anhydride-containing compounds and / or dibasic acids and diols, four stages are set: 155-165°C → 175-185°C → 195-205°C → 225-235°C. The main reactions are, in order, the reaction of anhydride with active alcohol hydroxyl groups, the reaction of active acid with active alcohol hydroxyl groups, the reaction of inert or sterically hindered functional groups, and the end (in the final stage, the monomer concentration is reduced, and heating helps to complete the reaction). The present invention team found that the four-stage gradient heating method is conducive to the formation of a three-dimensional spatial network of the film-forming resin, thereby making the antifouling coating have a better instantaneous thixotropic stabilization effect.

[0025] Furthermore, in step (2), the polycondensation reaction catalyst is monobutyltin oxide, and the molar ratio of the diol to the polycondensation reaction catalyst is 1:0.009 to 0.015.

[0026] Preferably, the specific process of step (3) includes the following steps: adding a compound containing at least two epoxy groups, solvent III and a ring-opening reaction catalyst to the product obtained in step (2), and reacting at 150-160° C. for 8-10 hours.

[0027] Furthermore, in step (3), the ring-opening reaction catalyst is triphenylphosphine, and the mass ratio of the compound containing at least two epoxy groups to the ring-opening reaction catalyst is 1:0.015 to 0.025.

[0028] Preferably, in step (1), the molar ratio of the acid anhydride to 1,4-cyclohexanedimethanol is 1:0.3-0.5.

[0029] Preferably, the molar ratio of the acid anhydride in step (1) to the acid anhydride-containing compound and / or dibasic acid, diol in step (2) is 1:1.0-1.7:1.0-1.5.

[0030] Preferably, the molar ratio of the acid anhydride in step (1) to the epoxy groups in the compound containing at least two epoxy groups in step (3) is 1:35 to 165.

[0031] Preferably, the number average molecular weight of the film-forming resin is 9900 to 12500.

[0032] Preferably, the antifouling coating comprises the following components in parts by weight: 35-60 parts of film-forming resin dispersion, 0-5 parts of auxiliary resin, 1-5 parts of mechanical accelerator, 0-16 parts of antifouling agent, 0-7 parts of pigment, 0-2 parts of plasticizer, 3-7 parts of auxiliary agent, and 10-25 parts of coating solvent.

[0033] Furthermore, the solid content of the film-forming resin dispersion is 50-55%.

[0034] Furthermore, the auxiliary resin includes one or more of rosin resin, butyl resin, styrene-butadiene resin, phenolic resin, silicone resin, amino resin, urea-formaldehyde resin, chloroether resin, modified polyethylene resin and polyurethane resin.

[0035] Furthermore, the mechanical promoter includes glass fiber and / or flaky quartz.

[0036] Furthermore, the antifouling agent includes one or more of cuprous oxide, copper pyrithione, zinc pyrithione, mancozeb, boric acid, SeaNine211, diuron, borneol, bromopyrrole carbonitrile, metoclopramide, borneol, propylene glycol menthyl carbonate, borax, menthamide, menthol, tannic acid, matrine, capsaicin, metaldehyde, molluscicide, 6-chloroindole, osthole and rotenone.

[0037] Furthermore, the plasticizer includes one or more of dibutyl phthalate, dioctyl phthalate, dioctyl phenyl phosphate, chlorinated paraffin, dioctyl phenyl phosphite and polyacrylamide.

[0038] Furthermore, the auxiliary agent includes one or more of a dispersant, a leveling agent, an anti-settling thixotropic agent and an antioxidant.

[0039] Furthermore, the coating solvent includes one or more of xylene, butanol, solvent oil and propylene glycol methyl ether.

[0040] In a second aspect, the present invention provides the use of the antifouling coating in antifouling of nets.

[0041] Preferably, the application comprises the following steps: dipping the antifouling paint onto the surface of the net to form an antifouling coating.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] (1) The antifouling coating of the present invention uses a film-forming resin synthesized by a special method, which has high hydrophilicity. Therefore, after the coating is formed on the net, it can have good antifouling performance, greatly reducing the amount of copper antifouling agents in the coating, so that the antifouling coating can meet environmental protection requirements;

[0044] (2) The film-forming resin used in the antifouling coating of the present invention has high flexibility and elasticity, which can reduce the impact of the antifouling coating on the expansion and contraction ability of the net, allowing the net to work normally;

[0045] (3) The film-forming resin used in the antifouling coating of the present invention has a three-dimensional spatial network, which can make the coating have a better instantaneous thixotropic stabilization effect, thereby improving its one-time wetting and covering rate on the net. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the embodiments.

[0047] Overall embodiment

[0048] An antifouling coating for nets, comprising a film-forming resin; a method for preparing the film-forming resin comprises the following steps:

[0049] (1) Using itaconic anhydride, 1,4-cyclohexanedimethanol and an initiator as raw materials, an esterification reaction between anhydride groups and hydroxyl groups is carried out, and an addition polymerization reaction of olefin groups is carried out to prepare compound I;

[0050] (2) using compound I, an anhydride-containing compound and / or a dibasic acid, and a diol as raw materials, to carry out a polycondensation reaction between an anhydride group and a carboxyl group and a hydroxyl group, or to carry out a polycondensation reaction between a carboxyl group and a hydroxyl group, to prepare a carboxyl-containing polymer II;

[0051] (3) Using a carboxyl-containing polymer II and a compound containing at least two epoxy groups as raw materials, a ring-opening reaction between the epoxy group and the carboxyl group is carried out to prepare a film-forming resin.

[0052] As a specific embodiment, in step (2), the anhydride-containing compound is hexahydrophthalic anhydride, the dibasic acid is adipic acid, and the diol is one or both of neopentyl glycol and tetraethylene glycol; in step (3), the compound containing at least two epoxy groups is polyethylene glycol diglycidyl ether having an epoxy value of 0.35 to 0.80.

[0053] As a specific embodiment, the specific process of step (1) includes the following steps: under the protection of inert gas, mixing itaconic anhydride, 1,4-cyclohexanedimethanol and solvent I, wherein the molar ratio of the itaconic anhydride to 1,4-cyclohexanedimethanol is 1:0.3-0.5, and the mass ratio of the itaconic anhydride to the initiator is 1:0.005-0.008, reacting at 60-70°C for 2.5-3.5h, then adding a portion of the initiator, reacting at 85-95°C for 1-2h, and then adding the remaining initiator, wherein the mass ratio of the portion of the initiator to the remaining initiator is 2.5-3.5:1, and continuing to react at 85-95°C for 1-2h.

[0054] As a specific embodiment, the specific process of step (2) includes the following steps: adding an anhydride-containing compound and / or a dibasic acid, a diol, a condensation reaction catalyst and a solvent II to the product obtained in step (1), wherein the molar ratio of the itaconic anhydride in step (1) to the anhydride-containing compound and / or the dibasic acid and the diol in step (2) is 1:1.0-1.7:1.0-1.5, and the molar ratio of the diol to the condensation reaction catalyst is 1:0.009-0.015, reacting at 155-165° C. for 1-2 hours, then heating to 175-185° C. and continuing to react for 1-2 hours, then heating to 195-205° C. and continuing to react for 6-24 hours, and finally heating to 225-235° C. and maintaining for 30-40 minutes.

[0055] As a specific embodiment, the specific process of step (3) includes the following steps: adding a compound containing at least two epoxy groups, solvent III and a ring-opening reaction catalyst to the product obtained in step (2), the molar ratio of the acid anhydride in step (1) to the epoxy groups in the compound containing at least two epoxy groups in step (3) is 1:35-165, the mass ratio of the compound containing at least two epoxy groups to the ring-opening reaction catalyst is 1:0.015-0.025, and the reaction is carried out at 150-160°C for 8-10 hours.

[0056] As a specific embodiment, the number average molecular weight of the film-forming resin is 9900-12500.

[0057] As a specific embodiment, it includes the following components in parts by weight: 35 to 60 parts of film-forming resin dispersion, 0 to 5 parts of auxiliary resin, 1 to 5 parts of mechanical accelerator, 0 to 16 parts of antifouling agent, 0 to 7 parts of pigment, 0 to 2 parts of plasticizer, 3 to 7 parts of auxiliary agent, and 10 to 25 parts of coating solvent.

[0058] In the above specific implementation:

[0059] The solid content of the film-forming resin dispersion is 50-55%;

[0060] The auxiliary resin may be selected from one or more of rosin resin, butyl resin, styrene-butadiene resin, phenolic resin, silicone resin, amino resin, urea-formaldehyde resin, chloroether resin, modified polyethylene resin and polyurethane resin;

[0061] The mechanical accelerator may be selected from glass fiber and / or flaky quartz;

[0062] The antifouling agent may be selected from one or more of cuprous oxide, copper pyrithione, zinc pyrithione, mancozeb, boric acid, SeaNine 211, diuron, borneol, bromopyrrole nitrile, metoclopramide, borneol, propylene glycol menthyl carbonate, borax, menthamide, menthol, tannic acid, matrine, capsaicin, metaldehyde, molluscicide, 6-chloroindole, osthole and rotenone;

[0063] The plasticizer may be selected from one or more of dibutyl phthalate, dioctyl phthalate, dioctyl phenyl phosphate, chlorinated paraffin, dioctyl phenyl phosphite and polyacrylamide;

[0064] The auxiliary agent may be selected from one or more of a dispersant, a leveling agent, an anti-settling thixotropic agent and an antioxidant;

[0065] The coating solvent may be selected from one or more of xylene, butanol, solvent oil and propylene glycol methyl ether.

[0066] The antifouling coating is used in antifouling of nets, and the steps are as follows: the antifouling coating is dip-coated on the surface of the net to form an antifouling coating.

[0067] Preparation Example 1: Preparation of film-forming resin

[0068] The film-forming resin R1 dispersion was prepared by the following steps:

[0069] (1) Under nitrogen protection, take 61.6g (0.55mol) of itaconic anhydride, 28.8g (0.2mol) of 1,4-cyclohexanedimethanol, and 91g of xylene, heat to 60℃, maintain for 3h, add 0.3g of azobisisobutyronitrile (AIBN), raise the temperature to 90℃, react for 1.5h, add 0.1g of AIBN, and continue to react for 1.5h.

[0070] (2) To the product obtained in step (1), 138.6 g (0.9 mol) of hexahydrophthalic anhydride, 83.2 g (0.8 mol) of neopentyl glycol, 1.5 g of monobutyltin oxide, and 60 g of xylene were added. After mixing, the temperature was raised to 160° C. and maintained for 1 h. The temperature was then raised to 180° C. and maintained for another 1 h. The temperature was then raised to 200° C. and maintained until the water output reached the theoretical value (9.9 g) (about 24 h). The temperature was then further raised to 230° C. and maintained for 0.5 h. The temperature was then lowered to 90° C. The calculated amount of xylene (150 g) was added to maintain the solid content at 50%. The measured acid value was 84, and the GPC measured molecular weight was 1200.

[0071] (3) Add 225 g of polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40), 230 g of xylene, and 5 g of triphenylphosphine (Ph3P) to the product obtained in step (2). Maintain the reaction temperature at 150°C for about 9 hours until the liquid turns dark yellow and the acid value is less than 3. Then terminate the reaction to obtain a dispersion of film-forming resin R1. The theoretical solid content of the resin is 50%, and the measured solid content is 51.8%. The final molecular weight M is 2.377 W / m, which is 0.13 W / m. w 36832, M n It is 9934 and the dispersion is 3.71.

[0072] The synthetic route of this preparation example is as follows:

[0073]

[0074] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 1.

[0075] Preparation Example 2: Preparation of film-forming resin

[0076] The film-forming resin R2 dispersion was prepared by the following steps:

[0077] (1) Under nitrogen protection, take 61.6g (0.55mol) of itaconic anhydride, 28.8g (0.2mol) of 1,4-cyclohexanedimethanol, and 91g of xylene, heat to 60℃, maintain for 3h, add 0.3g of azobisisobutyronitrile (AIBN), raise the temperature to 90℃, react for 1.5h, add 0.1g of AIBN, and continue to react for 1.5h.

[0078] (2) To the product obtained in step (1) were added 115.5 g (0.75 mol) of hexahydrophthalic anhydride, 83.2 g (0.8 mol) of neopentyl glycol, 1.5 g of monobutyltin oxide, and 60 g of xylene. After mixing, the mixture was heated to 160° C. and maintained for 1 h. The mixture was then heated to 180° C. and maintained for another 1 h. The mixture was then heated to 200° C. and maintained until the water output reached the theoretical value (12.6 g) (approximately 24 h). The mixture was then heated to 230° C. and maintained for 0.5 h. The mixture was then cooled to 90° C. The calculated amount of xylene (145 g) was added. The solid content was maintained at 50%. The measured acid value was 57, and the GPC molecular weight was 2000.

[0079] (3) Add 150 g of polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40), 154 g of xylene, and 3.5 g of triphenylphosphine (Ph3P) to the product obtained in step (2). Maintain the reaction temperature at 150°C for about 9 hours until the liquid turns dark yellow and the acid value is less than 3. Then terminate the reaction to obtain a dispersion of film-forming resin R2. The theoretical solid content of the resin is 50%, and the measured solid content is 52.1%. The final molecular weight M is 0.0447 W / m, as measured by GPC. w 43327, M n It is 12489 and the dispersion is 3.47.

[0080] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 1.

[0081] Preparation Example 3: Preparation of film-forming resin

[0082] The film-forming resin R3 dispersion was prepared by the following steps:

[0083] (1) Under nitrogen protection, take 61.6g (0.55mol) of itaconic anhydride, 28.8g (0.2mol) of 1,4-cyclohexanedimethanol, and 91g of xylene, heat to 60℃, maintain for 3h, add 0.3g of azobisisobutyronitrile (AIBN), raise the temperature to 90℃, react for 1.5h, add 0.1g of AIBN, and continue to react for 1.5h.

[0084] (2) To the product obtained in step (1) were added 84.7 g (0.55 mol) of hexahydrophthalic anhydride, 83.2 g (0.8 mol) of neopentyl glycol, 1.5 g of monobutyltin oxide, and 60 g of xylene. After mixing, the temperature was raised to 160° C. and maintained for 1 h. The temperature was then raised to 180° C. and maintained for another 1 h. The temperature was then raised to 200° C. and maintained until the water output reached the theoretical value (17.1 g) (approximately 24 h). The temperature was then further raised to 230° C. and maintained for 0.5 h. The temperature was then lowered to 90° C. The calculated amount of xylene (124 g) was added. The solid content was maintained at 50%. The measured acid value was 23, and the GPC measured molecular weight was 3000.

[0085] (3) Add 60 g of polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40), 62 g of xylene, and 1.5 g of triphenylphosphine (Ph3P) to the product obtained in step (2). Maintain the reaction temperature at 150°C for about 9 hours until the liquid turns dark yellow and the acid value is less than 3. Then terminate the reaction to obtain a film-forming resin R3 dispersion. The theoretical solid content of the resin is 50%, and the measured solid content is 52.2%. The final molecular weight M is 2.5777 W / m, which is 2.3777 W / m. w 47836, M n It is 11593 and the dispersion is 4.13.

[0086] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 1.

[0087] Preparation Example 4: Preparation of film-forming resin

[0088] According to the steps in Preparation Example 2, a dispersion of film-forming resin R4 was prepared. The only difference from Preparation Example 2 was that 83.2 g (0.8 mol) of neopentyl glycol in step (2) was replaced with 41.6 g (0.4 mol) of neopentyl glycol and 77.7 g (0.4 mol) of tetraethylene glycol. The remaining raw materials and preparation process were the same as those in Preparation Example 2.

[0089] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 1.

[0090] Preparation Example 5: Preparation of film-forming resin

[0091] According to the steps in Preparation Example 2, a dispersion of film-forming resin R5 was prepared. The only difference from Preparation Example 2 was that 150 g of polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40) in step (3) was replaced with 75 g of polyethylene glycol diglycidyl ether (epoxy value 0.70-0.80). The remaining raw materials and preparation process were the same as those in Preparation Example 2.

[0092] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 1.

[0093] Preparation Example 6: Preparation of film-forming resin

[0094] According to the steps in Preparation Example 4, a dispersion of film-forming resin R6 was prepared. The only difference from Preparation Example 4 was that 115.5 g (0.75 mol) of hexahydrophthalic anhydride in step (2) was replaced with 109.6 g (0.75 mol) of adipic acid. The remaining raw materials and preparation process were the same as those in Preparation Example 4.

[0095] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 2.

[0096] Preparation Example 7: Preparation of film-forming resin

[0097] According to the steps in Preparation Example 4, a dispersion of film-forming resin R7 was prepared. The only difference from Preparation Example 4 was that 150 g of polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40) in step (3) was replaced with 568 g of acrylic epoxy resin. The remaining raw materials and preparation process were the same as those in Preparation Example 4.

[0098] The preparation method of the acrylic epoxy resin used in this preparation example refers to patent ZL201811652868.4, using 100 g of isobornyl methacrylate, 60 g of glycidyl methacrylate, 20 g of lauryl methacrylate, 20 g of butyl methacrylate, 2.0 g of AIBN, and 202 g of xylene. The mixture is added dropwise at 90°C for 3 hours and kept warm for 3 hours to prepare a solid content of 50%.

[0099] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 2.

[0100] Preparation Example 8: Preparation of film-forming resin

[0101] According to the steps in Preparation Example 2, a dispersion of film-forming resin R8 was prepared. The only difference from Preparation Example 2 was that azobisisobutyronitrile was not added in step (1). The remaining raw materials and preparation process were the same as those in Preparation Example 2.

[0102] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 2.

[0103] Preparation Example 9: Preparation of film-forming resin

[0104] According to the steps in Preparation Example 2, a dispersion of film-forming resin R9 was prepared. The only difference from Preparation Example 2 was that the gradient temperature increase method was not used in step (2), that is, the process of "raising the temperature to 160°C after mixing, maintaining for 1 hour, raising the temperature to 180°C, continuing to maintain for 1 hour, raising the temperature to 200°C, and maintaining until the water output reached the theoretical value (12.6 g) (about 24 hours)" was replaced by "raising the temperature to 200°C after mixing, and maintaining until the water output reached the theoretical value (11.8 g)". The remaining raw materials and preparation process were the same as those in Preparation Example 2.

[0105] The test data of the amount of each reactant used in this preparation example, the intermediate product (i.e., the product of step (2)) and the film-forming resin are shown in Table 2.

[0106] Preparation Example 10

[0107] According to the steps in Preparation Example 2, a dispersion of film-forming resin R10 was prepared. The only difference from Preparation Example 2 was that step (3) was not performed, and the solid content of the product of step (2) was adjusted to the same as that of R2, and used as film-forming resin R10. The remaining raw materials and preparation process were the same as those in Preparation Example 2.

[0108] The amount of each reactant used in this preparation example and the test data of the film-forming resin dispersion are shown in Table 2.

[0109] Table 1 Amounts of reactants used and product test data for Preparation Examples 1 to 5

[0110]

[0111] Note:

[0112] 1 CHDM: 1,4-cyclohexanedimethanol (the same below);

[0113] 2 GDGE1: polyethylene glycol diglycidyl ether (epoxy value 0.35-0.40) (the same below);

[0114] 3 GDGE2: polyethylene glycol diglycidyl ether (epoxy value 0.70-0.80) (same below).

[0115] Table 2 Amounts of reactants used and product test data of Preparation Examples 6 to 10

[0116]

[0117] Analysis of test results:

[0118] (1) Compared with R4, the elongation at break of R7 is significantly reduced, indicating that compared with acrylic epoxy resin, the use of polyethylene glycol diglycidyl ether for chain extension can improve the toughness of the film-forming resin, which helps to reduce the impact of the antifouling coating on the stretchability of the net. The reason is speculated to be that acrylic epoxy resin has a large molecular weight and contains multiple epoxy groups, which will form multiple cross-linking points in the film-forming resin and have a high cross-linking density, resulting in lower toughness; while polyethylene glycol diglycidyl ether has a small molecular weight and only contains two terminal epoxy groups. While achieving chain extension, it can make the film-forming resin have more high molecular weight linear structures, thus making it have greater toughness.

[0119] (2) Compared to R2, R10 failed to form a film and could not measure its elongation at break. This indicates that chain extension of the product of step (2) using polyethylene glycol diglycidyl ether can improve the film-forming properties of the resin, forming a flexible paint film that helps withstand the effects of the mesh's expansion and contraction capabilities. This is presumably because chain extension using polyethylene glycol diglycidyl ether can further extend the resin chain, forming a macromolecular compound and imparting greater flexibility to the film-forming resin.

[0120] Examples 1-11: Antifouling coating for low-copper netting and its application on netting

[0121] According to the formulations in Tables 3 and 4 (the amounts of each component are expressed in mass percentage, i.e., the units are all wt%), low-copper antifouling coatings for mesh clothing of Examples 1 to 11 were prepared and designated R1Cu to R11Cu. The film-forming resin dispersions used in R1Cu to R10Cu were the R1 to R10 dispersions prepared in Preparation Examples 1 to 10, respectively, and the film-forming resin dispersion used in R11Cu was the R7 dispersion prepared in Preparation Example 7.

[0122] The nets were dip-coated with low-copper antifouling coatings R1Cu to R9Cu to form an antifouling coating on the net surface. The antifouling coatings were evaluated for antifouling and tested for abrasion rate. The results are shown in Table 2.

[0123] Table 3 Coating formulations and performance test data of Examples 1 to 7

[0124]

[0125]

[0126] Note:

[0127] 1 Six-month antifouling evaluation method: After being dipped in antifouling paint, nets were tested in the Luomen waters of Zhoushan, Zhejiang Province. Due to the lack of direct national standards for evaluating net antifouling paint, an indirect comparison method was used for evaluation: nets were compared with commercially available samples (i.e., samples from Comparative Examples 1 and 2). Nets with less fouling organisms than the commercially available samples were rated as excellent, those with indistinguishable fouling organisms were rated as good, and those with significantly more fouling organisms than the commercially available samples were rated as poor (the same applies below).

[0128] 2 Abrasion rate test method: According to GB / T 31411-2015, the test is carried out regularly every month and the coating abrasion amount is recorded (the same below).

[0129] Table 4 Coating formulations and performance test data of Examples 1 to 7

[0130]

[0131] Note:

[0132] 1 Comparative Example 1: provided by Hainan Kewei Functional Materials Co., Ltd. (the same below);

[0133] 2 Comparative Example 2: provided by Zhoushan Hengtai Paint Industry Co., Ltd. (the same below).

[0134] Analysis of test results:

[0135] (1) Compared with R2Cu, the one-time wetting and covering rate of R8Cu coating on the mesh is lower, indicating that in the process of preparing the film-forming resin, after the condensation of itaconic anhydride and 1,4-cyclohexanedimethanol, the initiator is used to cause the olefinic groups in itaconic anhydride to undergo an addition polymerization reaction, which can improve the one-time wetting and covering rate of the coating on the mesh. The reason is speculated to be that this addition polymerization reaction can make the film-forming resin have a three-dimensional spatial network, giving the coating a better instantaneous thixotropic stabilization effect, making it show better anti-sagging performance, thereby improving its one-time wetting and covering rate on the mesh.

[0136] (2) Compared with R2Cu, the R9Cu coating exhibited a lower one-time wetting and encapsulation rate on the mesh. This suggests that, during the preparation of the film-forming resin, a gradient temperature increase during the chain extension of Compound I using an anhydride-containing compound and / or a dibasic acid and a diol can improve the one-time wetting and encapsulation rate of the coating on the mesh. This is presumably because this gradient temperature increase facilitates the formation of a three-dimensional network in the film-forming resin, thereby imparting a better transient thixotropic stabilization effect to the antifouling coating.

[0137] (3) Compared with R4Cu, the antifouling performance of R11Cu is significantly reduced, indicating that in the process of preparing the film-forming resin, the use of polyethylene glycol diglycidyl ether for chain extension can improve the antifouling performance of the coating compared with the use of acrylic epoxy resin. The reason is speculated to be that: compared with acrylic epoxy resin, polyethylene glycol diglycidyl ether has a higher hydrophilicity, which can make the antifouling coating have better self-polishing properties in seawater; at the same time, unlike acrylic epoxy resin, polyethylene glycol diglycidyl ether has a smaller molecular weight and a structure with only two end epoxy groups, which can make the crosslinking density in the prepared film-forming resin relatively low, thereby increasing the abrasion rate of the film-forming resin in seawater.

[0138] Examples 8-14: Antifouling coating for copper-free nets and its application on nets

[0139] According to the formula in Table 3, the copper-free antifouling coatings for mesh clothes of Examples 8 to 14 were prepared and recorded as S1 to S7, wherein the film-forming resin dispersions used in S1 to S7 were the R1 to R7 dispersions prepared in Preparation Examples 1 to 7, respectively.

[0140] The nets were dip-coated with low-copper antifouling coatings S1 to S7 to form an antifouling coating on the net surface. The antifouling coatings were evaluated for antifouling and subjected to abrasion rate tests. The results are shown in Table 2.

[0141] Table 3 Coating formulations and performance test data of Examples 8 to 14

[0142]

[0143]

[0144] Analysis of test results:

[0145] As can be seen from Tables 1 and 2, the antifouling performance of low-copper antifouling coatings R1Cu-R6Cu and copper-free antifouling coatings S1-S7 is significantly higher than that of commercially available antifouling coatings (Comparative Examples 1 and 2), demonstrating that the film-forming resin prepared in this invention can impart superior antifouling performance to net-use antifouling coatings. Furthermore, during the antifouling evaluation process, the present invention team observed that nets coated with low-copper antifouling coatings showed biofouling after six months, while nets coated with copper-free antifouling coatings had a near-zero biofouling rate, indicating no visible biofouling (thanks to the highly effective green antifouling agent, bromopyrrolecarbonitrile).

[0146] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0147] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing an antifouling coating for net clothing, characterized in that: The following steps are involved: (1) Using itaconic anhydride, 1,4-cyclohexanedimethanol and an initiator as raw materials, an esterification reaction between anhydride groups and hydroxyl groups is carried out, and an addition polymerization reaction of olefin groups is carried out to prepare compound I; (2) adding an anhydride-containing compound and / or a dibasic acid, a diol, a polycondensation reaction catalyst and a solvent II to the product obtained in step (1), reacting at 155-165° C. for 1-2 hours, then heating to 175-185° C. for 1-2 hours, then heating to 195-205° C. for 6-24 hours, and finally heating to 225-235° C. for 30-40 minutes to prepare a carboxyl-containing polymer II; (3) Using carboxyl-containing polymer II and polyethylene glycol diglycidyl ether as raw materials, a ring-opening reaction between epoxy groups and carboxyl groups is carried out to prepare a film-forming resin; (4) Preparation of antifouling coatings for nets including film-forming resins.

2. The preparation method according to claim 1, wherein: In step (2), the anhydride-containing compound is hexahydrophthalic anhydride, and the dibasic acid is adipic acid; and / or In step (2), the diol is one or both of neopentyl glycol and tetraethylene glycol.

3. The preparation method according to claim 1, wherein The specific process of step (1) includes the following steps: under the protection of inert gas, itaconic anhydride, 1,4-cyclohexanedimethanol and solvent I are mixed, reacted at 60-70°C for 2.5-3.5 hours, and then a portion of the initiator is added, reacted at 85-95°C for 1-2 hours, and then the remaining initiator is added, and the reaction is continued at 85-95°C for 1-2 hours.

4. The preparation method according to claim 1, wherein The specific process of step (3) comprises the following steps: adding polyethylene glycol diglycidyl ether, solvent III and a ring-opening reaction catalyst to the product obtained in step (2), and reacting at 150-160° C. for 8-10 hours.

5. The preparation method according to claim 1 or 3, wherein In step (1), the molar ratio of itaconic anhydride to 1,4-cyclohexanedimethanol is 1:0.3-0.

5.

6. The preparation method according to claim 1 or 3, wherein The molar ratio of itaconic anhydride in step (1) to the anhydride-containing compound and / or dibasic acid, diol in step (2) is 1:1.0-1.7:1.0-1.

5.

7. The preparation method according to claim 1 or 4, characterized in that The molar ratio of the itaconic anhydride in step (1) to the epoxy group in the polyethylene glycol diglycidyl ether in step (3) is 1:35-165.

8. The preparation method according to claim 1, wherein The number average molecular weight of the film-forming resin is 9900~12500 Da.

9. The preparation method according to claim 1, wherein The antifouling paint for nets comprises the following components in parts by weight: 35-60 parts of film-forming resin dispersion, 0-5 parts of auxiliary resin, 1-5 parts of mechanical accelerator, 0-16 parts of antifouling agent, 0-7 parts of pigment, 0-2 parts of plasticizer, 3-7 parts of auxiliary agent, and 10-25 parts of paint solvent.

10. Use of the antifouling coating for nets prepared by the preparation method according to any one of claims 1 to 9 in antifouling of nets.

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