Multifunctional anticorrosive coating for marine severe corrosion environment and preparation process thereof

Abstract

The application discloses a multifunctional anticorrosion coating for marine harsh corrosive environment and a preparation process thereof. The anticorrosion coating adopts a three-layer composite structure of "adhesive layer-barrier layer-surface functional layer", and is composed of an adhesive layer material, a barrier film, a surface functional layer material and a carrier. The adhesive layer takes acrylic resin as a core, and adds components such as surface modified titanium dioxide and isocyanate curing agent to form an adhesive system with high adhesion and corrosion resistance; the barrier layer is a plasma modified polyvinylidene fluoride barrier film; and the surface functional layer takes fluorocarbon modified emulsion as a matrix, and is compounded with nano cuprous oxide, functional ceramic powder and anti-aging additives to provide anti-pollution, anti-corrosion and anti-ultraviolet functions. The application solves the technical limitations of single protection function and complex process in the prior art. The anticorrosion coating is suitable for marine harsh environments with high salt fog, high humidity and strong ultraviolet, and provides a long-acting anticorrosion solution with simple process and comprehensive performance for offshore wind power and other infrastructures.

Description

Technical Field

[0001] This invention relates to the field of corrosion protection materials technology, specifically to a multifunctional anti-corrosion coating for use in harsh marine corrosive environments and its preparation process. Background Technology

[0002] In applications involving complex marine environments, such as marine engineering, shipbuilding, coastal facilities, and offshore wind power, extremely stringent requirements are placed on the protective performance of materials. The marine environment is a typical harsh corrosive environment, characterized by prolonged high humidity, high salt spray, periodic wet-dry cycles, strong ultraviolet radiation, and marine organism attachment. These factors work synergistically to rapidly accelerate the corrosion of metal substrates, the aging of coatings, and functional failure. Currently, protective tapes used in marine or near-shore environments often have limitations in their technical solutions. Traditional marine anti-corrosion tapes often focus on a single anti-corrosion function. For example, Chinese patent CN118909560A discloses a graphene-reinforced anti-corrosion tape and its preparation method. This tape utilizes the synergistic effect of epoxy resin, graphene, and carbon nanotubes to form a dense network structure, ensuring both good corrosion resistance and the tape's ductility. However... Its long-term barrier effect against corrosive media such as chloride ions is limited, and it generally suffers from problems such as limited surface function, susceptibility to contamination, and poor weather resistance. When exposed to wave impact, sun exposure, and biological adhesion, its protective lifespan is significantly shortened.

[0003] To meet increasingly stringent challenges, existing technologies have introduced more complex multi-layered tape designs, attempting to improve overall performance through the layering of functional layers. Chinese patent CN106634705B discloses an anti-corrosion tape for marine engineering and its preparation method, employing a structure of "base film layer, first adhesive layer, reinforcing layer, second adhesive layer, and isolation layer" to improve the tape's adhesion, hydrophobicity, and corrosion resistance. However, its core adhesive layer relies on viscoelastic polymers such as polyisobutylene. The bonding mechanism of these materials is primarily physical adsorption, lacking active groups that form chemical bonds with the surface of damp substrates. Under seawater immersion conditions, the adhesive strength easily weakens and detaches due to interfacial moisture barrier. Furthermore, the raw material composition lacks antifouling components (such as cuprous oxide), relying solely on the inertness of corrosion inhibitors and the anti-corrosion adhesive itself, which cannot inhibit marine organism attachment. Biofouling damages the tape's surface integrity, causing functional components such as UV absorbers and antioxidants to fail, indirectly shortening the anti-corrosion lifespan. The reinforcing layer is a "high-density polyethylene mesh," but the mesh structure has limited impact and tear resistance, making it difficult to withstand strong water flow or impact from hard objects. Therefore, for complex marine environments, this type of design has significant shortcomings in terms of long-term resistance to media penetration, surface antifouling, corrosion prevention, anti-aging, and environmental stability.

[0004] In summary, there is an urgent need in this field to break through existing technological bottlenecks and develop a new type of multifunctional anti-corrosion coating that is specifically designed for complex marine environments, can solve the needs of adhesion, barrier, corrosion prevention, antifouling and weather resistance in an integrated manner, and has an efficient and stable preparation process. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art, and provides a multifunctional anti-corrosion coating for use in harsh marine corrosive environments and its preparation process.

[0006] In a first aspect, embodiments of the present invention provide a multifunctional anti-corrosion coating for use in harsh marine corrosive environments, comprising an adhesive layer, a barrier layer, a surface functional layer, and a carrier adhered to the inner side of the adhesive layer, arranged sequentially from bottom to top; wherein, The adhesive layer is based on acrylic resin, with added surface-modified titanium dioxide and isocyanate curing agent components; The barrier layer is a plasma-modified polyvinylidene fluoride barrier film; The surface functional layer uses fluorocarbon modified emulsion as the matrix and is compounded with nano cuprous oxide, functional ceramic powder and anti-aging additives.

[0007] Optionally, the adhesive layer comprises, by weight: 60-75 parts of acrylic resin; 5-8 parts of modified titanium dioxide nanoparticles; 8-12 parts of isocyanate curing agent; 3-5 parts copper-plated nylon fiber; 2-4 parts of zinc powder; 1-2 parts dispersant; 1 part defoamer; 5-8 parts deionized water.

[0008] Optionally, the acrylic resin and modified titanium dioxide nano-ceramic powder are mixed, and then in the resin dilution stage, a synergistic process of high-speed dispersion at 1500-2000 r / min for 20-30 min and ultrasonic treatment at 30-40 kHz for 10-20 min is used to uniformly mix the powder into the resin matrix. Finally, the weather resistance, mechanical and functional properties of the resin are efficiently modified through mechanical blending.

[0009] Optionally, an activation layer of polystyrene-block-polyethylene oxide is pre-coated on the inner side of the resin matrix; wherein the thickness of the polystyrene-block-polyethylene oxide is 0.05-0.1 mm.

[0010] Optionally, the preparation process of the modified titanium dioxide nanopowder includes: Titanium dioxide nanoparticles of 90-100 nm were mixed with deionized water at a volume ratio of 3:1 and dispersed by ultrasonication at 30-40 kHz for 5-10 minutes. Then, they were mixed with a silane coupling agent hydrolysate at a stoichiometric ratio and stirred at 80-100 °C and 500 r / min. After centrifugation, washing, and vacuum drying, the mixture was prepared. Its characteristic particle size D50 was 126±3.2 nm and D90 was 193±5.1 nm. The silane coupling agent was selected as γ-methacryloyloxypropyltrimethoxysilane.

[0011] Optionally, the thickness of the barrier layer is 0.5-1.0 mm; and / or, The carrier is a polyethylene film, integrally formed with a three-layer anti-corrosion coating; and / or, The thickness of the adhesive layer is 0.8~1.5mm, the thickness of the barrier layer is 0.5~1.0mm, the thickness of the surface functional layer is 0.3~0.8mm, the thickness of the carrier film is 0.15~0.2mm, and the overall anti-corrosion coating thickness is 2.0~3.5mm.

[0012] Optionally, the surface functional layer comprises, by weight: 45-55 parts of fluorocarbon modified emulsion; 10-12 parts of functional ceramic powder; 8-10 parts of cuprous oxide; 7-8 parts of benzotriazole UV absorber; 7-8 parts hindered amine light stabilizer; 4-5 parts of coupling agent; 2-3 parts dispersant; 6-7 parts of curing agent; 1-2 parts deionized water.

[0013] Optionally, the cuprous oxide is a slow-release mechanism of a three-stage gradient dissolution protection system consisting of "flower-shaped nano-cuprous oxide + organically coated cuprous oxide capsules + inorganically coated cuprous oxide". This mechanism constructs a staged ion release system in a high-strength substrate coating and uses a special coating method to treat the flower-shaped nano-Cu2O particles to achieve effective control over the timing of cuprous oxide release.

[0014] Secondly, embodiments of the present invention provide a process for preparing the multifunctional anti-corrosion coating for harsh marine corrosive environments described above, comprising the following steps: (1) By uniformly dispersing modified nano-titanium dioxide powder, copper-plated nylon fiber, zinc powder and other components in acrylic resin with the assistance of a dispersant, adding defoamer and finally mixing in isocyanate curing agent to form a homogeneous adhesive liquid. (2) The barrier layer uses plasma-modified polyvinylidene fluoride barrier film as the core substrate. Its dense crystalline structure and chemical inertness can build an efficient corrosion medium barrier. The film material is placed in a vacuum or atmospheric pressure plasma chamber, and oxygen or air is introduced as the process gas. High-frequency electric field is used to generate high-energy particles to bombard the film surface, causing the molecular chain to break and generate active free radical sites. Then, it reacts with the active oxygen species in the plasma to oxidize and graft polar functional groups such as hydroxyl and carboxyl groups on the film surface, so that it can form hydrogen bonds and van der Waals forces with the active groups in the lower adhesive layer to achieve tight adhesion. At the same time, the surface micro-rough structure allows the functional ceramic powder of the upper protective layer to be embedded and anchored to form a stable composite interface. (3) The cuprous oxide antifouling component and the functional ceramic powder anticorrosion component are uniformly dispersed by silane coupling agent and dispersant to construct a synergistic protection system; benzotriazole ultraviolet absorber and hindered amine light stabilizer are compounded simultaneously to form a photochemical dual anti-aging barrier, which is then cross-linked by curing agent to form a dense coating. (4) First coating: The plasma-modified PVDF barrier film is installed on the unwinding device of the coating machine. The unwinding tension is adjusted to 3~5N to ensure stable transport of the carrier. The prepared adhesive slurry is injected into the material tank of the coating machine and the slurry circulation system is started to ensure that the slurry is evenly distributed between the doctor blade and the a-side of the barrier film to avoid the generation of air bubbles. After the barrier film is coated by the doctor blade, it enters the continuous drying oven. The oven temperature is set in stages and kept at a temperature of 20~30min to allow the semi-cured adhesive layer to adhere to the a-side of the barrier film. By utilizing the adhesiveness of the adhesive layer and the interaction between the polar groups on the film surface and the active groups of the adhesive layer, a tight bond is achieved, and the peel strength can reach 8~12N / 25mm. After bonding, the film is gently pressed by the pressure roller to ensure that the film and the adhesive layer are completely bonded without air bubbles. (5) Second coating: The semi-finished anti-corrosion coating with the composite barrier layer is sent to the coating machine. The unwinding tension is adjusted to 4~6N to prevent the anti-corrosion coating from being stretched and deformed. The slit exit gap is 0.3~0.8mm. The surface functional layer slurry is sent into the slit coating head by a high-pressure pump. The slurry supply pressure is controlled at 0.3~0.5MPa to ensure that the slurry flows out continuously and stably, and evenly covers the b-side of the PVDF barrier film without any interruption or sagging. During the coating process, the functional ceramic powder in the slurry will naturally embed into the micro-rough structure of the PVDF barrier film surface, forming a stable composite interface through interfacial physical anchoring. After curing, the surface hardness of the coating is ≥4H, and there are no bubbles or pinhole defects.

[0015] Optionally, in steps (4) and (5), the gap between the coating machine blades is set to 0.8~1.5mm, and the coating speed is set to 1~3m / min; and / or, In step (5), after coating, the anti-corrosion coating is placed in a room temperature curing zone and allowed to cure naturally for 2-4 hours. Then, it is transferred to a low-temperature oven for 1-2 hours to promote the bonding between the light stabilizer and the resin, while simultaneously strengthening the physical anchoring effect between the functional ceramic powder and the PVDF barrier film. This invention relates to a multifunctional anti-corrosion coating and its preparation process for harsh marine corrosive environments. Addressing the technical challenges of barnacles and other marine organisms easily proliferating in tidal zones, and the severe biofouling and corrosion aging faced by marine engineering facilities in these areas, this invention provides a three-layer composite structure of an adhesive layer, a barrier layer, and a surface functional layer. The surface functional layer not only provides anti-corrosion and anti-aging functions but also creates a bio-inhibitory environment through controlled release of copper ions, effectively inhibiting the attachment and growth of barnacles and other marine organisms. This constructs a synergistic protection system of anti-corrosion, anti-biofouling, and anti-aging, significantly extending the service life of marine engineering facilities in tidal zones and achieving long-term stable protection. The barrier layer reduces the number of coating layers required. Utilizing the unique properties of plasma-modified PVDF barrier film, it forms hydrogen bonds and van der Waals forces with the adhesive layer and a physical anchoring bond with the surface functional layer, simplifying the process while ensuring interlayer bonding strength. PVDF barrier membranes have extremely strong weather resistance and their performance does not degrade even after long-term immersion in seawater. They are perfectly suited for marine working conditions with high salt spray and high humidity, providing core barrier support for the overall protection system and ensuring the long-term anti-corrosion performance of the anti-corrosion coating. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Unless otherwise specifically stated, the technical or scientific terms used in the embodiments of this invention should be understood in their ordinary sense by those skilled in the art to which this invention pertains. The terms "comprising" or "including," as used in the embodiments of this invention, do not limit the shapes, numbers, steps, actions, operations, components, elements, and / or groups thereof mentioned, nor do they exclude the appearance or addition of one or more other different shapes, numbers, steps, actions, operations, components, elements, and / or groups thereof, or the addition of these. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number and order of the indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] In the description of the embodiments of the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In the embodiments of the present invention, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in the embodiments of the present invention, as well as the features of different embodiments or examples.

[0019] Example 1 A multifunctional anti-corrosion coating, comprising the following materials in 100 parts each: Adhesive layer – 65 parts acrylic resin, 6 parts modified titanium dioxide nanopowder, 10 parts isocyanate curing agent, 4 parts copper-plated nylon fiber, 3 parts zinc powder, 1 part dispersant, 1 part defoamer, and 10 parts deionized water. Surface functional layer – 50 parts fluorocarbon modified emulsion, 11 parts functional ceramic powder, 9 parts cuprous oxide, 8 parts benzotriazole UV absorber, 7 parts hindered amine light stabilizer, 4 parts coupling agent, 3 parts dispersant, 7 parts curing agent, and 1 part deionized water.

[0020] A method for preparing a multifunctional anti-corrosion coating includes the following steps: (a) Prepare the following materials according to the formula ratio: acrylic resin, modified nano-titanium dioxide powder, isocyanate curing agent, copper-plated nylon fiber, and zinc powder. The modified nano-titanium dioxide powder needs to be prepared in advance: mix 100nm titanium dioxide nanoparticles with deionized water at a volume ratio of 3:1, disperse by ultrasonication at 40kHz for 10 minutes, then mix with silane coupling agent hydrolysate at a stoichiometric ratio, stir and react at 80℃ and 500r / min, centrifuge, wash, and vacuum dry before use (characteristic particle size D50 is 126±3.2nm, D90 is 193±5.1nm); the acrylic resin needs to be pre-modified with nano-titanium dioxide ceramic powder, and a 0.05mm thick polystyrene-block-polyethylene oxide activation layer should be coated on the inner side of the resin matrix. (b) Plasma-modified polyvinylidene fluoride (PVDF) was selected as the barrier membrane. The membrane was placed in a plasma chamber with a vacuum of 50 Pa and air was introduced as the process gas. High-energy particles were generated under a high-frequency electric field with a power of 150 W and a frequency of 13.56 MHz. After 60 seconds of continuous bombardment, the molecular chains on the membrane surface were broken, generating active free radical sites. These sites then reacted with active oxygen species in the plasma to form an oxidation reaction. Finally, polar functional groups such as hydroxyl and carboxyl groups were grafted onto the membrane surface to ensure the bonding performance with the adhesive layer. The membrane surface retained a micro-rough structure, which laid the foundation for the physical anchoring with the surface functional layer. (c) Prepare fluorocarbon modified emulsion, functional ceramic powder, benzotriazole UV absorbers, hindered amine light stabilizers, and other materials. A three-stage, tiered protection system with a slow-release mechanism of "flower-shaped nano-cuprous oxide + organically coated cuprous oxide capsules + inorganically coated cuprous oxide" is adopted. The functional ceramic powder needs to be treated with a silane coupling agent to improve dispersion stability and inhibit photocatalytic activity, ensuring effective physical anchoring with the PVDF barrier membrane. (d) Adhesive layer slurry: After premixing acrylic resin and deionized water according to the weight parts, dispersant, modified nano titanium dioxide powder and zinc powder are added in sequence. The mixture is stirred at high speed of 1500 r / min for 20 minutes and the temperature is controlled at ≤45℃ to achieve complete dispersion of nano powder. Then, the speed is reduced to 600 r / min and copper-plated nylon fiber is added and dispersed for 10 minutes. Then, defoamer is added and defoamed at low speed for 5 minutes. Finally, the material is cooled to below 30℃ and isocyanate curing agent is slowly added and mixed for 10 minutes under low speed stirring to finally form a uniform, stable and non-agglomerated adhesive layer slurry.

[0021] Surface functional layer slurry: Mix the materials according to the weight ratio, stir at 600 rpm for 25 minutes at room temperature, and then disperse at 1400 rpm for 75 minutes using a high-speed disperser to ensure that the functional components are evenly dispersed, especially the functional ceramic powder, to form the surface functional layer slurry.

[0022] (e) First Coating: Install the plasma-modified PVDF barrier film onto the unwinding device of the coating machine, adjust the unwinding tension to 3N, and ensure stable carrier transport. Set the doctor blade gap of the coating machine to 0.8mm and the coating speed to 1.5m / min. Inject the prepared adhesive slurry into the coating machine's slurry tank, start the slurry circulation system, and ensure that the slurry is evenly distributed between the doctor blade and the barrier film surface a, avoiding the generation of air bubbles. After the barrier film is coated with a doctor blade, it enters a continuous drying oven with segmented temperature settings (130℃ for the first segment, 145℃ for the middle segment, and 160℃ for the last segment). The temperature is maintained for 20-30 minutes. Immediately afterwards, the semi-cured adhesive layer is bonded to side a of the barrier film. Utilizing the adhesiveness of the adhesive layer and the interaction between the polar groups on the film surface and the active groups of the adhesive layer (forming hydrogen bonds and van der Waals forces), a tight bond is achieved, with a peel strength of 8-12 N / 25 mm. After bonding, a pressure roller is used to gently press the film to ensure complete adhesion between the film and the adhesive layer without air bubbles. The pressure roller pressure is 0.2 MPa, and the rotation speed is synchronized with the coating speed.

[0023] (e) Second coating: The semi-finished anti-corrosion coating with the composite barrier layer is sent to the coating machine (slit coating machine). The unwinding tension is adjusted to 4N to prevent the anti-corrosion coating from being stretched and deformed. The coating width is set to match the width of the anti-corrosion coating, the coating speed is 2m / min, and the slit exit gap is 0.3~0.8mm. The surface functional layer slurry is sent into the slit coating head by a high-pressure pump. The slurry supply pressure is controlled at 0.3MPa to ensure that the slurry flows out continuously and stably, and evenly covers the b-side of the PVDF barrier film without any interruption or sagging. During the coating process, the functional ceramic powder in the slurry will naturally embed into the micro-rough structure of the PVDF barrier film surface, forming a stable composite interface through interfacial physical anchoring. After coating, the anti-corrosion coating is placed in the room temperature curing zone and cured naturally for 2-4 hours. Then it is transferred to a low temperature oven (60-80℃) and kept at that temperature for 1-2 hours to promote the bonding between the light stabilizer and the resin, while strengthening the physical anchoring effect between the functional ceramic powder and the PVDF barrier film. After curing, the surface hardness of the coating is ≥4H (pencil hardness test), and there are no defects such as bubbles or pinholes.

[0024] (f) After the surface functional layer is fully cured, the laminating machine covers the polyethylene carrier film and the lamination pressure is 0.2MPa to ensure tight bonding and easy peeling. The film is then wound up with a tension of 8N and cut to the specified width (accuracy ±0.5mm) by a cutting machine.

[0025] Example 2 A multifunctional anti-corrosion coating, comprising the following materials in 100 parts each: Adhesive layer – 60 parts acrylic resin, 6 parts modified titanium dioxide nanopowder, 12 parts isocyanate curing agent, 5 parts copper-plated nylon fiber, 5 parts zinc powder, 2 parts dispersant, 1 part defoamer, and 9 parts deionized water. Surface functional layer – 48 parts fluorocarbon modified emulsion, 12 parts functional ceramic powder, 8 parts cuprous oxide, 8 parts benzotriazole UV absorber, 8 parts hindered amine light stabilizer, 5 parts coupling agent, 2 parts dispersant, 8 parts curing agent, and 1 part deionized water.

[0026] A method for preparing a multifunctional anti-corrosion coating includes the following steps: (a) Prepare the following materials according to the formula ratio: acrylic resin, modified nano-titanium dioxide powder, isocyanate curing agent, copper-plated nylon fiber, and zinc powder. The modified nano-titanium dioxide powder needs to be prepared in advance: mix 100nm titanium dioxide nanoparticles with deionized water at a volume ratio of 3:1, disperse by ultrasonication at 40kHz for 10 minutes, then mix with silane coupling agent hydrolysate at a stoichiometric ratio, stir and react at 100℃ and 500r / min, centrifuge, wash, and vacuum dry before use (characteristic particle size D50 is 126±3.2nm, D90 is 193±5.1nm); the acrylic resin needs to be pre-modified with nano-titanium dioxide ceramic powder, and a 0.05-0.1mm thick polystyrene-block-polyethylene oxide activation layer should be coated on the inner side of the resin matrix. (b) Plasma-modified polyvinylidene fluoride (PVDF) was selected as the barrier membrane. The membrane was placed in a plasma chamber with a vacuum of 20 Pa and oxygen was introduced as the process gas. High-energy particles were generated under a high-frequency electric field with a power of 250 W and a frequency of 13.56 MHz. After 90 seconds of continuous bombardment, the molecular chains on the membrane surface were broken, generating active free radical sites. These sites then reacted with active oxygen species in the plasma to form an oxidation reaction. Finally, polar functional groups such as hydroxyl and carboxyl groups were grafted onto the membrane surface to ensure the bonding performance with the adhesive layer. The membrane surface retained a micro-rough structure, which laid the foundation for physical anchoring with the surface functional layer. (c) Prepare fluorocarbon modified emulsion, functional ceramic powder, benzotriazole UV absorbers, hindered amine light stabilizers, and other materials. A three-stage, tiered protection system with a slow-release mechanism of "flower-shaped nano-cuprous oxide + organically coated cuprous oxide capsules + inorganically coated cuprous oxide" is adopted. The functional ceramic powder needs to be treated with a silane coupling agent to improve dispersion stability and inhibit photocatalytic activity, ensuring effective physical anchoring with the PVDF barrier membrane. (d) Adhesive layer slurry: After premixing acrylic resin and deionized water according to the weight parts, dispersant, modified nano titanium dioxide powder and zinc powder are added in sequence. The mixture is stirred at high speed of 2000 r / min for 25 minutes and the temperature is controlled at ≤45℃ to achieve complete dispersion of nano powder. Then, the speed is reduced to 800 r / min and copper-plated nylon fiber is added and dispersed for 15 minutes. Then, defoamer is added and defoamed at low speed for 5 minutes. Finally, the material is cooled to below 30℃ and isocyanate curing agent is slowly added and mixed for 15 minutes under low speed stirring to form a uniform, stable and non-agglomerated adhesive layer slurry.

[0027] Surface functional layer slurry: Mix the materials according to the weight ratio, stir at 600 rpm for 25 minutes at room temperature, and then disperse at 1400 rpm for 75-80 minutes using a high-speed disperser to ensure that the functional components are evenly dispersed, especially the functional ceramic powder, to form the surface functional layer slurry.

[0028] (e) First Coating: Install the plasma-modified PVDF barrier film onto the unwinding device of the coating machine, and adjust the unwinding tension to 5N to ensure stable carrier transport. Set the doctor blade gap of the coating machine to 1.5mm and the coating speed to 2.5m / min. Inject the prepared adhesive slurry into the coating machine's slurry tank, start the slurry circulation system, and ensure that the slurry is evenly distributed between the doctor blade and the barrier film surface a to avoid air bubbles. After the barrier film is coated with a doctor blade, it enters a continuous drying oven with segmented temperature settings (140℃ for the first segment, 155℃ for the middle segment, and 165℃ for the last segment). The temperature is maintained for 15-20 minutes, and then the semi-cured adhesive layer is immediately bonded to side a of the barrier film. By utilizing the adhesiveness of the adhesive layer and the interaction between the polar groups on the film surface and the active groups of the adhesive layer (forming hydrogen bonds and van der Waals forces), a tight bond is achieved, with a peel strength of 8-12 N / 25 mm. After bonding, the film is gently pressed by a pressure roller to ensure complete adhesion between the film and the adhesive layer without air bubbles. The pressure roller pressure is 0.3 MPa, and the rotation speed is synchronized with the coating speed.

[0029] (e) Second coating: The semi-finished anti-corrosion coating with the composite barrier layer is sent to the coating machine (micro-recessed coating machine). The unwinding tension is adjusted to 3N to prevent the anti-corrosion coating from being stretched and deformed. The coating width is set to match the width of the anti-corrosion coating, the coating speed is 3m / min, and the slit exit gap is 0.3~0.8mm. The surface functional layer slurry is sent into the slit coating head by a high-pressure pump. The slurry supply pressure is controlled at 0.5MPa to ensure that the slurry flows out continuously and stably, and evenly covers the b-side of the PVDF barrier film without any interruption or sagging. During the coating process, the functional ceramic powder in the slurry will naturally embed into the micro-rough structure of the PVDF barrier film surface, forming a stable composite interface through interfacial physical anchoring. After coating, the anti-corrosion coating is placed in the room temperature curing zone and cured naturally for 2-4 hours. Then it is transferred to a low temperature oven (60-80℃) and kept at that temperature for 1-2 hours to promote the bonding between the light stabilizer and the resin, while strengthening the physical anchoring effect between the functional ceramic powder and the PVDF barrier film. After curing, the surface hardness of the coating is ≥4H (pencil hardness test), and there are no defects such as bubbles or pinholes.

[0030] (f) After the surface functional layer is fully cured, the laminating machine covers the polyethylene carrier film and the lamination pressure is 0.3MPa to ensure tight bonding and easy peeling. The film is then wound up with a tension of 12N and cut to the specified width (accuracy ±0.5mm) by a cutting machine.

[0031] Comparative Example 1 Raw material ratio adjustment: Remove zinc powder from the adhesive layer, and replace "flower-shaped nano cuprous oxide + organically coated cuprous oxide capsules + inorganically coated cuprous oxide" with an equal mass of ordinary cuprous oxide in the surface functional layer. The raw material ratios of the remaining layers are the same as in Example 1.

[0032] The preparation process is exactly the same as in Example 1.

[0033] Comparative Example 2 The raw material ratio is the same as in Example 2.

[0034] Preparation process: The PVDF barrier membrane is not subjected to plasma treatment, nor is the silica nanoparticles modified with coupling agents. The remaining processes are exactly the same as in Example 2.

[0035] Effect Comparison The samples from Examples 1-2 and Comparative Examples 1-2 were tested experimentally, and the test results are shown in the table below: Table 1 Comparison of the performance of various anti-corrosion coatings

[0036] As can be seen from Table 1, in Examples 1-2, the oxidative volume expansion of zinc powder in the adhesive layer can compensate for the microcracks and provide sacrificial anode protection. This, combined with the conductive network of copper-plated nylon fibers and the plasma modification of the PVDF barrier film to enhance interfacial bonding, results in significantly higher bonding strength and self-healing ability compared to the comparative examples. In Comparative Example 1, the lack of zinc powder leads to a decrease in interfacial bonding stability. In Comparative Example 2, the lack of PVDF modification and powder coupling treatment results in a significant decrease in interfacial bonding strength.

[0037] Examples 1-2 employ a three-stage, stepped, slow-release cuprous oxide system to control the release of copper ions for long-lasting antifouling; Comparative Example 1 replaces it with ordinary cuprous oxide, which rapidly releases copper ions and then becomes ineffective, resulting in a significantly increased adhesion rate.

[0038] In Examples 1-2, the modified titanium dioxide and the "ultraviolet absorber + light stabilizer" work synergistically to resist ultraviolet rays. In Comparative Example 2, the powder was not modified, and the photocatalytic activity led to resin degradation, resulting in the worst anti-aging performance.

[0039] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A multifunctional anti-corrosion coating for use in harsh marine corrosive environments, characterized in that, It includes, from bottom to top, an adhesive layer, a barrier layer, a surface functional layer, and a carrier adhered to the inner side of the adhesive layer; wherein, The adhesive layer is based on acrylic resin, with added surface-modified titanium dioxide and isocyanate curing agent components; The barrier layer is a plasma-modified polyvinylidene fluoride barrier film; The surface functional layer uses fluorocarbon modified emulsion as the matrix and is compounded with nano cuprous oxide, functional ceramic powder and anti-aging additives.

2. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 1, characterized in that, By weight, the adhesive layer comprises: 60-75 parts of acrylic resin; 5-8 parts of modified titanium dioxide nanoparticles; 8-12 parts of isocyanate curing agent; 3-5 parts copper-plated nylon fiber; 2-4 parts of zinc powder; 1-2 parts dispersant; 1 part defoamer; 5-8 parts deionized water.

3. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 2, characterized in that, The acrylic resin and modified titanium dioxide nano-ceramic powder are mixed, and then in the resin dilution stage, a synergistic process of high-speed dispersion at 1500-2000 r / min for 20-30 min and ultrasonic treatment at 30-40 kHz for 10-20 min is used to uniformly mix the powder into the resin matrix. Finally, the resin's weather resistance, mechanical and functional properties are efficiently modified through mechanical blending.

4. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 2, characterized in that, The inner side of the resin matrix is ​​pre-coated with an activation layer of polystyrene-block-polyethylene oxide; wherein the thickness of the polystyrene-block-polyethylene oxide is 0.05-0.1 mm.

5. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 2, characterized in that, The preparation process of the modified titanium dioxide nanopowder includes: Titanium dioxide nanoparticles of 90-100 nm were mixed with deionized water at a volume ratio of 3:1 and dispersed by ultrasonication at 30-40 kHz for 5-10 minutes. Then, they were mixed with a silane coupling agent hydrolysate at a stoichiometric ratio and stirred at 80-100 °C and 500 r / min. After centrifugation, washing, and vacuum drying, the mixture was prepared. Its characteristic particle size D50 was 126±3.2 nm and D90 was 193±5.1 nm. The silane coupling agent was selected as γ-methacryloyloxypropyltrimethoxysilane.

6. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 1, characterized in that, The thickness of the barrier layer is 0.5-1.0 mm; and / or, The carrier is a polyethylene film, integrally formed with a three-layer anti-corrosion coating; and / or, The thickness of the adhesive layer is 0.8~1.5mm, the thickness of the barrier layer is 0.5~1.0mm, the thickness of the surface functional layer is 0.3~0.8mm, the thickness of the carrier film is 0.15~0.2mm, and the overall anti-corrosion coating thickness is 2.0~3.5mm.

7. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 1, characterized in that, By weight, the surface functional layer comprises: 45-55 parts of fluorocarbon modified emulsion; 10-12 parts of functional ceramic powder; 8-10 parts of cuprous oxide; 7-8 parts of benzotriazole UV absorber; 7-8 parts hindered amine light stabilizer; 4-5 parts of coupling agent; 2-3 parts dispersant; 6-7 parts of curing agent; 1-2 parts deionized water.

8. The multifunctional anti-corrosion coating for harsh marine corrosive environments according to claim 7, characterized in that, The cuprous oxide described is a slow-release mechanism of a three-stage gradient dissolution protection system consisting of "flower-shaped nano-cuprous oxide + organically coated cuprous oxide capsules + inorganically coated cuprous oxide". This mechanism constructs a staged ion release system in a high-strength substrate coating and uses a special coating method to treat the flower-shaped nano-Cu2O particles in order to effectively control the timing of cuprous oxide release.

9. A preparation process for a multifunctional anti-corrosion coating for harsh marine corrosive environments according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) By uniformly dispersing modified nano-titanium dioxide powder, copper-plated nylon fiber, zinc powder and other components in acrylic resin with the assistance of a dispersant, adding defoamer and finally mixing in isocyanate curing agent to form a homogeneous adhesive liquid. (2) The barrier layer uses plasma-modified polyvinylidene fluoride barrier film as the core substrate. Its dense crystalline structure and chemical inertness can build an efficient corrosion medium barrier. The film material is placed in a vacuum or atmospheric pressure plasma chamber, and oxygen or air is introduced as the process gas. High-frequency electric field is used to generate high-energy particles to bombard the film surface, causing the molecular chain to break and generate active free radical sites. Then, it reacts with the active oxygen species in the plasma to oxidize and graft polar functional groups such as hydroxyl and carboxyl groups on the film surface, so that it can form hydrogen bonds and van der Waals forces with the active groups in the lower adhesive layer to achieve tight adhesion. At the same time, the surface micro-rough structure allows the functional ceramic powder of the upper protective layer to be embedded and anchored to form a stable composite interface. (3) The cuprous oxide antifouling component and the functional ceramic powder anticorrosion component are uniformly dispersed by silane coupling agent and dispersant to construct a synergistic protection system; benzotriazole ultraviolet absorber and hindered amine light stabilizer are compounded simultaneously to form a photochemical dual anti-aging barrier, which is then cross-linked by curing agent to form a dense coating. (4) First coating: The plasma-modified PVDF barrier film is installed on the unwinding device of the coating machine. The unwinding tension is adjusted to 3~5N to ensure stable transport of the carrier. The prepared adhesive slurry is injected into the material tank of the coating machine and the slurry circulation system is started to ensure that the slurry is evenly distributed between the doctor blade and the a-side of the barrier film to avoid the generation of air bubbles. After the barrier film is coated by the doctor blade, it enters the continuous drying oven. The oven temperature is set in stages and kept at a temperature of 20~30min to allow the semi-cured adhesive layer to adhere to the a-side of the barrier film. By utilizing the adhesiveness of the adhesive layer and the interaction between the polar groups on the film surface and the active groups of the adhesive layer, a tight bond is achieved, and the peel strength can reach 8~12N / 25mm. After bonding, the film is gently pressed by the pressure roller to ensure that the film and the adhesive layer are completely bonded without air bubbles. (5) Second coating: The semi-finished anti-corrosion coating with the composite barrier layer is sent to the coating machine, and the unwinding tension is adjusted to 4~6N to prevent the anti-corrosion coating from being stretched and deformed. The slit outlet gap is 0.3~0.8mm; the surface functional layer slurry is pumped into the slit coating head through a high-pressure pump, and the slurry supply pressure is controlled at 0.3~0.5MPa to ensure that the slurry flows out continuously and stably, and evenly covers the b side of the PVDF barrier film without any coating breaks or sagging. During the coating process, the functional ceramic powder in the slurry naturally embeds into the microscopic rough structure of the PVDF barrier film surface, forming a stable composite interface through interfacial physical anchoring. After curing, the coating surface hardness is ≥4H, with no bubbles or pinhole defects.

10. The preparation process according to claim 9, characterized in that, In steps (4) and (5), the blade gap of the coating machine is set to 0.8~1.5mm, and the coating speed is 1~3m / min; and / or, In step (5), the anti-corrosion coating is placed in the room temperature curing zone and cured naturally for 2-4 hours. Then it is transferred to the low temperature oven for 1-2 hours to promote the combination of light stabilizer and resin, and at the same time strengthen the physical anchoring effect of functional ceramic powder and PVDF barrier film.

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