A connecting paint for a ship and a preparation method and application thereof

Abstract

The present application relates to a kind of connecting paint for ship and its preparation method and application, belong to the field of coating technology.The connecting paint includes A component and B component;Wherein, A component includes cashew phenol-based epoxy resin, functional cashew phenol-based epoxy resin;B component includes cashew phenol modified amine curing agent.Functional cashew phenol-based epoxy resin is obtained by grafting cashew phenol-based epoxy resin with low degree of polymerization's mercapto end group polysulfobetaine methacrylate and side chain mercapto polydimethylsiloxane by thiol-alkene click reaction.The connecting paint of the present application is antifouling itself, can still inhibit attachment after finish coat is damaged, and can be well adhered with various types of finish coat interlayer without coupling agent.

Description

Technical Field

[0001] This invention relates to the field of marine coating technology, and in particular to a marine bonding paint, its preparation method, and its application. Background Technology

[0002] Ship antifouling coating systems typically consist of an epoxy anticorrosive primer, a bonding coat, and an antifouling topcoat. The bonding coat is responsible for establishing a reliable interface between the primer and the topcoat, which is crucial for the long-term integrity of the coating.

[0003] However, existing bonding coatings have two major problems. First, they lack antifouling capabilities and rely entirely on the topcoat for protection. When the topcoat is damaged by mechanical forces, aging, or localized by erosion, the bonding coating and primer are directly exposed to seawater, allowing bacteria, algae, barnacles, and other organisms to rapidly attach and multiply, leading to localized failure and accelerated spread. Second, they exhibit poor interlayer adhesion with different types of topcoats. Among mainstream topcoats, silicone-based topcoats have extremely low surface energy (approximately 20-25 mN / m) and low reactivity, making them difficult to bond with epoxy bonding coatings; acrylic topcoats contain ester groups, limiting their hydrogen bonding with epoxy systems; and traditional rosin-copper topcoats contain resin acids, resulting in unsatisfactory compatibility. Existing bonding coatings typically only work with one type of topcoat, making it difficult to accommodate multiple types, which can easily lead to interlayer delamination and poor bonding in practical engineering.

[0004] Therefore, there is an urgent need to develop a marine bonding paint that has its own antifouling capabilities and can reliably adhere to a variety of antifouling topcoats. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a marine bonding paint that has its own antifouling ability and can reliably adhere to a variety of antifouling topcoats, as well as its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a bonding paint for ships, comprising component A and component B; wherein component A comprises cashew nut shell epoxy resin and functionalized cashew nut shell epoxy resin; and component B comprises a cashew nut shell modified amine curing agent. The mass ratio of component A to component B is (8~12):1; In component A, the mass ratio of the functionalized cashew nut phenol-based epoxy resin to the cashew nut phenol-based epoxy resin is (0.4~1.0):1; wherein, the preparation method of the functionalized cashew nut phenol-based epoxy resin includes the following steps: Cashew phenol-based epoxy resin was grafted with mercapto-terminated polysulfobetaine methacrylate and side-chain mercapto-polydimethylsiloxane, and impurities were removed to obtain functionalized cashew phenol-based epoxy resin; the degree of polymerization of the mercapto-terminated polysulfobetaine methacrylate was 2 to 5.

[0007] Existing marine bonding paints typically lack inherent antifouling capabilities, relying entirely on antifouling topcoats for protection. Furthermore, the interlayer adhesion between bonding paints and different types of antifouling topcoats is poor, making it difficult to achieve compatibility with various topcoats. This invention provides a two-component marine bonding paint, comprising a functionalized cashew nut shell epoxy resin, obtained through a grafting reaction of the cashew nut shell epoxy resin with mercapto-terminated polysulfobetaine methacrylate and side-chain mercapto-polydimethylsiloxane.

[0008] Among them, the C of cashew phenol-based epoxy resin 15 The side chain contains carbon-carbon double bonds, which can undergo a thiol-ene click reaction with mercapto-terminated polysulfobetaine methacrylate and side chain mercapto polydimethylsiloxane, thereby covalently grafting the polysulfobetaine segment and the polydimethylsiloxane segment onto the cashew phenolic epoxy resin molecule.

[0009] Thiol-terminated polysulfobetaine methacrylate is an oligomer and is key to the synergistic effect of antifouling and interfacial adhesion. The oligomerized polysulfobetaine segments readily exist in a collapsed conformation in the dry state of the coating, without significantly interfering with the interfacial bonding between the binder and the topcoat. When the antifouling topcoat is partially damaged or seawater intrudes, these segments can undergo multi-arm outward orientation, forming a hydration layer at the exposed interface. Through the synergistic hydration of multiple sulfobetaine units, the adhesion of marine organisms such as bacteria, algae, and barnacles is inhibited, allowing the binder to still provide biocide-free antifouling protection in the damaged area of ​​the topcoat, thus delaying the spread of localized coating system failure. Compared to the "point-like hydration" (1~2 nm, only one zwitterion head group) of a single zwitterion, the multiple head groups of the low-polymer betaine of this application have a synergistic orientation that improves the anti-protein adsorption performance by 3~5 times; compared to the "brush-like hydration" (5~20 nm) of polymers, the low-polymer polymer of this invention has good solubility in organic solvents, high grafting efficiency, and no effect on the viscosity of component A, and its engineering feasibility is significantly better than that of the polymer solution.

[0010] Grafting of side-chain mercapto-polydimethylsiloxane primarily addresses the adhesion issue with silicone-based topcoats. This segment shares similar chemical properties and surface energy with silicone-based topcoats, allowing it to accumulate at the interface between the binder and the topcoat, achieving physical compatibility through the principle of "like dissolves like." This structure lowers the interfacial energy barrier between the binder and low-surface-energy silicone-based topcoats, enhancing interlayer bonding and enabling the binder to reliably adhere to both contamination-releasing topcoats and non-contamination-releasing topcoats, rather than being limited to a single type of topcoat.

[0011] This invention also limits the mass ratio of functionalized cashew nut shell epoxy resin to cashew nut shell epoxy resin in component A to balance antifouling function and coating bulk performance. The functionalized resin provides polysulfobetaine segments and polydimethylsiloxane segments, while the unfunctionalized cashew nut shell epoxy resin provides the epoxy curing network, adhesion, and application properties. This mass ratio avoids insufficient compatibility between antifouling and silicone-based topcoats due to an excessively low proportion of functionalized resin, and also avoids a decrease in system viscosity, crosslinking density, or interlayer adhesion due to an excessively high proportion. This ensures that the bonding paint maintains good application performance and storage stability while also providing antifouling properties and adhesion to multiple topcoats. Furthermore, the mass ratio of component A to component B in this invention ensures the formation of a suitable crosslinking network between epoxy and amine groups, resulting in a complete crosslinked structure after curing and a stable interface with the primer and topcoat.

[0012] As a preferred embodiment of the marine bonding paint of the present invention, the structural formula of the cashew phenol-based epoxy resin is shown in Formula I: Formula I: CH2(O)CHCH2-O-[C6H3(R1)-CH2]m-C6H3(R1)-O-CH2CH(O)CH2; Wherein, R1 is a C-type carbon containing 1-3 carbon-carbon double bonds. 15 Straight-chain unsaturated alkyl groups, selected from -C 15 H 29 (Monoolefin chain), -C 15 H 27 (diene chain) or -C 15 H 25 One or more of the following (triene chains); m = 0~3; epoxy groups are represented by CH2(O)CH- (three-membered ethylene oxide ring). In Formula I, the epoxy group formed by the glycidyl etherification of the phenolic hydroxyl group reacts with an amine curing agent to form a film, C 15 The carbon-carbon double bonds on the side chain serve as grafting anchors for the mercapto-alkene click chemistry reaction, while the long-chain alkyl groups endow the resin with internal toughening, hydrophobicity, and structural similarity and compatibility with traditional rosin-based topcoats. The side-chain mercaptopolydimethylsiloxane is shown in Formula II below: Formula II: CH3-[Si(CH3)2O] a -[Si(R2)O] b -Si(CH3)3; Where R2 is -(CH2)3-SH; a and b are integers. In the structure of Formula II, the polydimethylsiloxane backbone imparts intrinsic compatibility with FR silicone-based topcoats, and multiple side chain thiol groups can react with C 15Different carbon-carbon double bonds on the side chain undergo thiol-alkene reactions to form multi-point anchoring grafts, which are firm and do not detach. The side chain thiol polydimethylsiloxane can be a commercially available product, such as Gelest SMS-042 or Shin-Etsu KF-2001 (thiol equivalent of about 1900 g / mol, thiol content of about 0.53 mmol / g) or a product of equivalent specifications.

[0013] By defining the specific structures of the resin and siloxane, the reaction sites of carbon-carbon double bonds and mercapto groups can be clearly identified, which is beneficial for the selective occurrence of thiol-ene click reactions, ensuring the structural stability of the grafted product, and thus improving the reproducibility of the bonding paint performance.

[0014] In a preferred embodiment of the marine bonding paint described in this invention, the cashew phenol-based epoxy resin has an epoxy equivalent of 450-500 g / eq. Epoxy equivalent refers to the mass of resin containing 1 equivalent of epoxy groups (i.e., 1 mol of epoxy groups), expressed in g / eq (grams per equivalent). This range provides a moderate epoxy group density, ensuring sufficient crosslinking density to guarantee the cohesive strength of the coating while avoiding excessive epoxy group concentration that could lead to increased curing shrinkage and brittleness. This facilitates the formation of a flexible yet robust interface between the primer and topcoat.

[0015] In a preferred embodiment of the marine bonding paint described in this invention, the content of thiol groups in the side-chain thiol-containing polydimethylsiloxane is 0.3~1.0 mmol / g. This content range allows control over the grafting density of the polydimethylsiloxane segments, balancing interfacial compatibility and application stability.

[0016] As a preferred embodiment of the marine bonding paint of the present invention, the preparation method of the mercapto-terminated polysulfobetaine methacrylate includes the following steps: A1. Dissolve sulfobetaine methacrylate monomer, chain transfer agent and initiator in an aqueous solution of the first solvent to obtain solution X; A2. Inert gas is introduced into solution X, and the reaction is carried out at 60~80℃ for 3~5 hours under an inert gas atmosphere. After cooling to room temperature, solution Y is obtained. A3. Add solution Y dropwise into cold diethyl ether to precipitate, filter and collect the precipitate, and dry it under vacuum to obtain the intermediate; A4. Dissolve the intermediate in a second solvent, add excess n-butylamine, and stir the reaction under an inert gas atmosphere for 1.5 to 2.5 hours to obtain solution Z; A5. Solution Z was added dropwise to cold diethyl ether to precipitate the precipitate. The precipitate was collected by filtration and dried under vacuum to obtain mercapto-terminated polysulfobetaine methacrylate.

[0017] In a preferred embodiment of the marine bonding paint described in this invention, the cashew phenol-modified amine curing agent has an amine value of 250-300 mgKOH / g. The amine value is a parameter characterizing the basic nitrogen content in an amine compound, defined as the mass of potassium hydroxide required to neutralize all basic amine groups in 1 gram of sample, expressed in mgKOH / g. This amine value range ensures that the basic nitrogen content in the curing agent matches the epoxy equivalent, guaranteeing sufficient cross-linking between the epoxy groups and amine hydrogens, avoiding incomplete curing or excessive curing agent, and promoting the formation of a uniform and dense cross-linked network in the coating, thereby improving interlayer adhesion and seawater resistance.

[0018] In a preferred embodiment of the marine bonding paint of the present invention, component A further includes one or more of the following: reactive diluent, anti-settling agent, wetting and dispersing agent, pigment, filler, and solvent; and component B further includes accelerator and solvent.

[0019] As a further preferred embodiment of the marine bonding paint of the present invention, the reactive diluent includes benzyl glycidyl ether; the anti-settling agent includes one or more of organobentonite, polyamide wax, and fumed silica; the wetting and dispersing agent includes one or more of block copolymer dispersants and polyether-modified polysiloxanes; the pigment includes titanium dioxide; the filler includes one or more of barium sulfate and mica powder; the accelerator includes phenyl dimethylamine; and the solvent includes one or more of butyl acetate, xylene, and n-butanol.

[0020] As a preferred embodiment of the marine bonding paint of the present invention, the preparation method of the functionalized cashew phenol-based epoxy resin includes the following steps: S1. Dissolve cashew phenolic epoxy resin with butyl acetate, add mercapto-terminated polysulfobetaine methacrylate, side-chain mercapto polydimethylsiloxane, and photoinitiator, mix well to obtain solution C; S2. An inert gas is introduced into solution C. Under an inert gas atmosphere, the solution is subjected to 365 nm ultraviolet light at an intensity of 8~12 mW / cm². 2 Under the given conditions, the reaction proceeds for 1.5–2.5 hours to obtain solution D; S3. Solution D is added dropwise to methanol to precipitate, filtered, and dried under vacuum to obtain functionalized cashew phenol-based epoxy resin.

[0021] This method employs a UV-initiated thiol-olefin click reaction, which selectively acts on the carbon-carbon double bonds of the C15 side chain of cashew phenolic epoxy resin without affecting the epoxy groups. The reaction conditions are mild and the grafting efficiency is high.

[0022] Secondly, the present invention also provides the application of the aforementioned marine bonding paint in marine coatings. This bonding paint is used between an epoxy anti-corrosion primer and an antifouling topcoat, providing self-fouling protection in the event of localized damage to the topcoat, and forming reliable interlayer adhesion with various antifouling topcoats such as self-polishing, fouling-releasing, and rosin-copper types, thereby improving the long-term integrity and service life of the marine antifouling coating system.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves the effects of self-fouling of the bonding paint, continued protection after the topcoat is damaged, good adhesion between multiple antifouling topcoat layers and no need for external coupling agents, and solves the technical problems of existing bonding paints relying on topcoat for antifouling and poor compatibility of multiple topcoats. Detailed Implementation

[0024] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] In the following examples, the cashew phenolic epoxy resin is derived from Cardlite NC-514.

[0026] In the following examples, the fumed silica is derived from Wacker H18.

[0027] In the following examples, the organic bentonite was derived from Chang'an Renheng C72.

[0028] In the following examples, the block copolymer dispersant is derived from BYK-163.

[0029] In the following examples, the polyether-modified polysiloxane is derived from Tego 4100.

[0030] In the following examples, methoxy polyethylene glycol (PEG-350) was sourced from Liaoning Kelong Fine Chemical Co., Ltd.

[0031] In the following examples, the cashew phenol-modified amine curing agent is derived from Hensamine-1009.

[0032] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0033] Example 1 This invention discloses an embodiment of a marine bonding paint. The marine bonding paint of this embodiment is composed of component A and component B, with a mass ratio of component A to component B of 10:1. Component A, based on 100 parts by weight, comprises 15 parts functionalized cashew nut shell epoxy resin, 23 parts cashew nut shell epoxy resin, 5 parts benzyl glycidyl ether, 0.5 parts organobentonite, 1 part fumed silica, 0.67 parts block copolymer dispersant, 0.33 parts polyether-modified polysiloxane, 8 parts titanium dioxide, 11.5 parts barium sulfate, 5 parts mica powder, 15 parts butyl acetate, 10 parts xylene, and 5 parts n-butanol. Component B, based on 100 parts by weight, comprises 80 parts cashew nut shell modified amine curing agent, 2 parts phenyl dimethylamine, 10 parts butyl acetate, 5 parts xylene, and 3 parts n-butanol.

[0034] The preparation method of the functionalized cashew phenol-based epoxy resin described in this embodiment is as follows: S1. Mix and dissolve 100 g of cashew phenolic epoxy resin and 50 g of butyl acetate, add 13.8 g of mercapto-terminated polysulfobetaine methacrylate, 14 g of side-chain mercapto polydimethylsiloxane and 1.2 g of Irgacure 1173 photoinitiator, mix evenly, and purge with nitrogen to remove oxygen for 20 minutes. S2. Under a nitrogen atmosphere, under 365 nm ultraviolet light with a light intensity of 10 mW / cm². 2 The reaction was carried out under the specified conditions for 2 hours. After the reaction was completed, the product was dropped into methanol to precipitate, filtered, and dried under vacuum to obtain functionalized cashew phenolic epoxy resin.

[0035] The preparation method of mercapto-terminated polysulfonyl betaine methacrylate is as follows: A1. The sulfobetaine methacrylate monomer, CPADB chain transfer agent and AIBN initiator are dissolved in a mixed solvent of methanol and water in a molar ratio of 6:2:0.6 to obtain solution X.

[0036] A2. Nitrogen gas was introduced to remove oxygen for 30 minutes, and the reaction was carried out at 70°C for 4 hours under nitrogen atmosphere. After cooling to room temperature, solution Y was obtained.

[0037] A3. Add the reaction solution dropwise into cold diethyl ether to precipitate, filter and collect the precipitate, and dry it under vacuum to obtain the intermediate.

[0038] A4. Dissolve the intermediate in methanol, add n-butylamine in 10 molar excess relative to CPADB chain transfer agent, stir at 25°C for 2 hours to carry out aminolysis, convert the trithiocarbonate end group to a mercapto group, and the reaction is carried out under nitrogen protection throughout the process to obtain solution Z.

[0039] A5. Solution Z was added dropwise to cold diethyl ether to precipitate the precipitate. The precipitate was collected by filtration and dried under vacuum to obtain mercapto-terminated polysulfonyl betaine with a degree of polymerization of 3.

[0040] Example 2 An embodiment of the marine bonding paint of the present invention differs from Example 1 only in that the molar ratio of sulfobetaine methacrylate monomer, CPADB chain transfer agent and AIBN initiator in step A1 of the preparation method of mercapto-terminated polysulfobetaine methacrylate is 8:2:0.6, and the degree of polymerization of the obtained mercapto-terminated polysulfobetaine is 4.

[0041] Example 3 An embodiment of the marine bonding paint of the present invention differs from Example 1 only in that the molar ratio of sulfobetaine methacrylate monomer, CPADB chain transfer agent and AIBN initiator in step A1 of the preparation method of mercapto-terminated polysulfobetaine methacrylate is 10:2:0.6, and the degree of polymerization of the obtained mercapto-terminated polysulfobetaine is 5.

[0042] Example 4 This invention provides an embodiment of a marine bonding paint, which differs from Embodiment 1 only in that it contains 11 parts of functionalized cashew nut phenol-based epoxy resin and 27 parts of cashew nut phenol-based epoxy resin.

[0043] Example 5 This invention provides an embodiment of a marine bonding paint, which differs from Embodiment 1 only in that it contains 19 parts of functionalized cashew nut phenol-based epoxy resin and 19 parts of cashew nut phenol-based epoxy resin.

[0044] Example 6 This invention provides an embodiment of a marine bonding paint, which differs from Embodiment 1 only in that component A is 8 parts and component B is 1 part.

[0045] Example 7 This invention provides an embodiment of a marine bonding paint, which differs from Embodiment 1 only in that component A is 12 parts and component B is 1 part.

[0046] Comparative Example 1 This invention provides a comparative example of a marine bonding paint. The only difference between this comparative example and Example 1 is the presence of 9 parts of functionalized cashew phenol-based epoxy resin and 29 parts of cashew phenol-based epoxy resin.

[0047] Comparative Example 2 This invention provides a comparative example of a marine bonding paint. The only difference between this comparative example and Example 1 is the presence of 21 parts of functionalized cashew nut phenol-based epoxy resin and 17 parts of cashew nut phenol-based epoxy resin.

[0048] Comparative Example 3 This invention provides a comparative example of a marine bonding paint. The only difference between this comparative example and Example 1 is that component A is 6 parts and component B is 1 part.

[0049] Comparative Example 4 This invention provides a comparative example of a marine bonding paint. The only difference between this comparative example and Example 1 is that component A is 14 parts and component B is 1 part.

[0050] Comparative Example 5 This invention provides a comparative example of a marine bonding paint. The only difference between this comparative example and Example 1 is that the functionalized cashew phenol-based epoxy resin is replaced with methoxy polyethylene glycol (PEG-350).

[0051] Comparative Example 6 This invention provides a comparative example of a marine bonding paint. The difference between this comparative example and Example 1 is that no mercapto-terminated polysulfobetaine methacrylate is added during the preparation of the functionalized cashew phenol-based epoxy resin.

[0052] Comparative Example 7 This invention provides a comparative example of a marine bonding paint. The difference between this comparative example and Example 1 is that no side-chain mercapto polydimethylsiloxane is added in the preparation of the functionalized cashew phenol-based epoxy resin.

[0053] Comparative Example 8 This invention provides a comparative example of a marine bonding paint. The difference between this comparative example and Example 1 is that the mercapto-terminated polysulfobetaine methacrylate is replaced with mercapto-sulfobetaine methacrylate.

[0054] Comparative Example 9 This invention provides a comparative example of a marine bonding paint. The difference between this comparative example and Example 1 lies only in the preparation method of the mercapto-terminated polysulfobetaine methacrylate: the molar ratio of sulfobetaine methacrylate monomer, CPADB chain transfer agent, and AIBN initiator in step A1 is 20:2:0.6, the reaction time is 12 h, and the degree of polymerization of the resulting mercapto-terminated polysulfobetaine is 10. In the subsequent preparation of the functionalized cashew phenol-based epoxy resin, an additional 10% by mass of methanol is added as a solubilizer.

[0055] Comparative Example 10 This invention provides a comparative example of a bonding paint for ships. The difference between this comparative example and Example 1 is that mercapto-terminated polysulfobetaine methacrylate is not added when preparing the functionalized cashew phenol-based epoxy resin. Instead, the same mass fraction is added to the bonding paint in the same way as when preparing the functionalized cashew phenol-based epoxy resin, and the mixture is only physically mixed.

[0056] Example of effect This effect example examines the application test of the bonding paint of Examples 1-6 and Comparative Examples 1-10. The specific test method is as follows: a sandblasted steel plate (Sa 2.5 grade) is used to simulate the hull of a ship, and (1) epoxy primer (derived from Guangdong Daer New Materials Co., Ltd. DR-MPC901) is sprayed in sequence, with a dry film thickness of 100 μm and cured at room temperature for 24 h. (2) bonding paint of Examples 1-6 and Comparative Examples 1-10, with a dry film thickness of 70 μm and cured at room temperature for 24 h. (3) Antifouling topcoat (three types were sprayed separately: acrylic-copper copolymer matrix (SPC type, sourced from Guangdong Daer New Materials Co., Ltd. DR-MPC906), polydimethylsiloxane (FR type, sourced from Hempaguard silicone antifouling paint), and rosin-copper (rosin type, sourced from Guangdong Daer New Materials Co., Ltd. DR-MPC906N), with a dry film thickness of 175 μm and a curing time of 7 days at room temperature. The specific interlayer adhesion and the interlayer adhesion retention rate after immersion in shallow sea for one growing season (12 months) were tested (the test method for interlayer adhesion is GB / T 5210-2006).

[0057] Another sample without topcoat was prepared according to the above method. It was subjected to a shallow sea immersion test in shallow sea for one growing season in accordance with GB / T 5370-2007. Its flexibility (GB / T 1731-2020), impact resistance (GB / T 1732-2020), salt spray resistance (GB / T 10125-2021), and dynamic simulation test for three cycles in accordance with GB / T 7789-2007 were also tested.

[0058] Shallow sea immersion qualification: The shallow sea immersion performance evaluation of antifouling paint should assess the antifouling properties and physical state of the paint film separately. If the contaminated area of ​​the test panel exceeds 10%, it is judged as unqualified.

[0059] Dynamic simulation qualification assessment: The assessment should evaluate the antifouling properties of the antifouling paint and the physical state of the paint film separately. If the contaminated area of ​​the test panel exceeds 10%, it is judged as unqualified.

[0060] The specific test results are shown in Table 1.

[0061] Table 1 Examples 1-3 and Comparative Examples 8-9 show that the degree of polymerization of mercapto-terminated polysulfobetaine methacrylate directly affects its antifouling properties and overall performance. When the degree of polymerization is 3-5, the bonding paint exhibits stable antifouling properties, good adhesion, and good mechanical properties. Comparative Example 8 uses small-molecule zwitterions, which, although not interfering with the interface, fails to meet antifouling standards in shallow sea immersion and dynamic simulated antifouling. Comparative Example 9 uses high-molecular-weight betaine with a degree of polymerization of 10, achieving acceptable antifouling, but requiring methanol for solubility, reducing flexibility to 5 mm, impact resistance to 35 cm, and also exhibiting poor adhesion and salt spray resistance. Therefore, a degree of polymerization of 2-5 is the necessary range to balance antifouling, solubility, and workability.

[0062] As can be seen from Examples 1, 4, 5 and Comparative Examples 1, 2, when the mass ratio of functionalized cashew nut epoxy resin to cashew nut epoxy resin is lower than the lower limit of the present invention, the functionalized chain segments are insufficient, resulting in a decrease in self-fouling and compatibility with the fouling-releasing topcoat; when it is higher than the upper limit of the present invention, the crosslinking network and adhesion contribution provided by the unfunctionalized resin are insufficient, resulting in an imbalance between the viscosity and crosslinking density of the system.

[0063] As can be seen from Examples 1, 6, 7 and Comparative Examples 3, 4, when the mass ratio of component A to component B is lower than the lower limit of the present invention, the amine curing agent is excessive, which easily leads to excessive cross-linking or residual amine; when it is higher than the lower limit of the present invention, the epoxy group is not completely cured, the cross-linking network is incomplete, and the adhesion and durability decrease.

[0064] As can be seen from Comparative Examples 5-7, 10 and Example 1, covalent grafting and essential components are irreplaceable. Comparative Example 5, which uses methoxy polyethylene glycol as a physical blend instead of functionalized resin, exhibits low adhesion in all three types of topcoats, with the fouling-releasing topcoat showing an adhesion below 3 MPa and a retention rate of only 25-45% after seawater immersion. Comparative Example 6, lacking mercapto-terminated polysulfobetaine methacrylate, shows similar adhesion but lacks self-antifouling ability. Comparative Example 7, lacking side-chain mercapto-polydimethylsiloxane, shows a fouling-releasing topcoat with an adhesion of only 2.5 MPa and a retention rate of only 35% after immersion. Comparative Example 10, which only physically mixes sulfobetaine without covalent grafting, shows similar initial adhesion, but a retention rate of only 48-55% after seawater immersion, far lower than the 80-88% of the Example. The above comparisons indicate that the low-polymerization degree of sulfobetaine, polydimethylsiloxane segments, and covalent grafting structure collectively determine the self-antifouling ability, multi-topcoat adhesion, and seawater durability of the bonding paint.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A bonding paint for ships, characterized in that, It includes component A and component B; component A includes cashew nut shell phenol-based epoxy resin and functionalized cashew nut shell phenol-based epoxy resin; component B includes cashew nut shell phenol-modified amine curing agent; The mass ratio of component A to component B is (8~12):1; In component A, the mass ratio of the functionalized cashew nut phenol-based epoxy resin to the cashew nut phenol-based epoxy resin is (0.4~1.0):1; wherein, the preparation method of the functionalized cashew nut phenol-based epoxy resin includes the following steps: Cashew phenol-based epoxy resin was grafted with mercapto-terminated polysulfobetaine methacrylate and side-chain mercapto-polydimethylsiloxane, and impurities were removed to obtain functionalized cashew phenol-based epoxy resin; the degree of polymerization of the mercapto-terminated polysulfobetaine methacrylate was 2 to 5.

2. The marine bonding paint as described in claim 1, characterized in that, The structural formula of the cashew phenol-based epoxy resin is shown in Formula I below: Form I: CH2(O)CH-CH2-O-[C6H3(R1)-CH2] m -C6H3(R1)-O-CH2CH(O)CH2; Wherein, R1 is a C-type carbon containing 1 to 3 carbon-carbon double bonds. 15 Straight-chain unsaturated alkyl groups, m = 0~3; The side-chain mercaptopolydimethylsiloxane is shown in Formula II below: Formula II: CH3-[Si(CH3)2O] a -[Si(R2)O] b -Si(CH3)3; Where R2 is -(CH2)3-SH; a and b are arbitrary integers.

3. The marine bonding paint as described in claim 2, characterized in that, The epoxy equivalent of the cashew phenol-based epoxy resin is 450~500 g / eq.

4. The marine bonding paint as described in claim 2, characterized in that, The content of thiol groups in the side-chain thiol polydimethylsiloxane is 0.3~1.0 mmol / g.

5. The marine bonding paint as described in claim 1, characterized in that, The preparation method of the mercapto-terminated polysulfonyl betaine methacrylate includes the following steps: A1. Dissolve sulfobetaine methacrylate monomer, chain transfer agent and initiator in a first solvent to obtain solution X; A2. Inert gas is introduced into solution X, and the reaction is carried out at 60~80℃ for 3~5 hours under an inert gas atmosphere. After cooling to room temperature, solution Y is obtained. A3. Add solution Y dropwise into cold diethyl ether to precipitate, filter and collect the precipitate, and dry it under vacuum to obtain the intermediate; A4. Dissolve the intermediate in a second solvent, add excess n-butylamine, and stir the reaction under an inert gas atmosphere for 1.5 to 2.5 hours to obtain solution Z; A5. Solution Z was added dropwise to cold diethyl ether to precipitate the precipitate. The precipitate was collected by filtration and dried under vacuum to obtain mercapto-terminated polysulfobetaine methacrylate.

6. The marine bonding paint as described in claim 1, characterized in that, The amine value of the cashew phenol modified amine curing agent is 250~300 mgKOH / g.

7. The marine bonding paint as described in claim 1, characterized in that, Component A further includes one or more of the following: reactive diluent, anti-settling agent, wetting and dispersing agent, pigment, filler, and solvent; Component B further includes accelerator and solvent.

8. The marine bonding paint as described in claim 7, characterized in that, The reactive diluent includes benzyl glycidyl ether; the anti-settling agent includes one or more of organobentonite, polyamide wax, and fumed silica; the wetting and dispersing agent includes one or more of block copolymer dispersants and polyether-modified polysiloxanes; the pigment includes titanium dioxide; the filler includes one or more of barium sulfate and mica powder; the accelerator includes phenyl dimethylamine; and the solvent includes one or more of butyl acetate, xylene, and n-butanol.

9. The marine bonding paint as described in claim 1, characterized in that, The preparation method of the functionalized cashew phenol-based epoxy resin includes the following steps: S1. Dissolve cashew phenolic epoxy resin with butyl acetate, add mercapto-terminated polysulfobetaine methacrylate, side-chain mercapto polydimethylsiloxane, and photoinitiator, mix well to obtain solution C; S2. An inert gas is introduced into solution C. Under an inert gas atmosphere, the solution is subjected to 365 nm ultraviolet light at an intensity of 8~12 mW / cm². 2 Under the given conditions, the reaction proceeds for 1.5–2.5 h to obtain solution D; S3. Solution D is added dropwise to methanol to precipitate, filtered, and dried under vacuum to obtain functionalized cashew phenol-based epoxy resin.

10. The application of the marine bonding paint as described in any one of claims 1 to 9 in marine coatings.

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