Environment-friendly long-acting antifouling paint and preparation method thereof

Abstract

The invention discloses an environment-friendly long-acting antifouling paint and a preparation method thereof, and belongs to the technical field of paint materials and antifouling. The environment-friendly long-acting antifouling paint comprises the following components in parts by weight: 30-50 parts of a component A, 25-45 parts of a component B, 8-25 parts of a functional body, 1-5 parts of color paste and 0.3-3 parts of an auxiliary agent, the component A is an aliphatic isocyanate prepolymer which is prepared from aliphatic isocyanate and castor oil through a reaction, and the specific preparation raw materials comprise the following components in parts by weight: 20-40 parts of aliphatic isocyanate and 10-20 parts of castor oil; the component B is polyaspartic acid ester, and the molecular weight of the polyaspartic acid ester is 800-1500 g / mol; the castor oil has good reaction activity with aliphatic isocyanate, can significantly improve the flexibility of a prepolymer (polyurea precursor) and the cohesiveness with a base material, and can optimize the compatibility of the polyurea precursor with polyaspartic acid ester with the molecular weight of 800-1500 g / mol, thereby improving the mechanical stability and weather resistance of the whole polyurea paint coating. The technical problem that an existing coating material cannot give consideration to synergistic improvement of environmental protection property and mechanical property is solved.

Description

Technical Field

[0001] This invention relates to the field of coating materials and antifouling technology, and more specifically to an environmentally friendly, long-lasting antifouling coating and its preparation method. Background Technology

[0002] Antifouling coatings are functional coatings that effectively prevent biofouling, oil, dust, and other contaminants from adhering to the surface of a substrate, and are widely used in various protective applications. With rapid industrial development and increasingly stringent environmental requirements, the problems of traditional antifouling coatings, such as poor antifouling durability, insufficient environmental friendliness, weak mechanical properties, and lack of decorative appeal, are becoming increasingly prominent. Especially in complex environments such as marine, humid, and public facilities, coatings are prone to peeling and contamination, not only affecting the appearance but also accelerating substrate corrosion, shortening material lifespan, and significantly increasing maintenance costs.

[0003] Currently, existing two-component antifouling coating technologies suffer from the following core defects: First, the compatibility between A and B components is poor. Most technologies use aromatic isocyanates to prepare prepolymers, which have poor resistance to yellowing and are prone to aging and discoloration with long-term use. Furthermore, the reaction rate with amino components is difficult to control precisely, seriously affecting the coating's molding quality. Second, it is difficult to synergistically improve antifouling durability and mechanical properties. Although organosilicon modification can improve antifouling performance, it leads to a decrease in the coating's mechanical strength and weakened adhesion to the substrate, making it prone to peeling and damage. On the other hand, simply strengthening mechanical properties sacrifices the antifouling effect. Third, environmental performance is insufficient. Some antifouling coatings contain toxic biocides such as tin and copper, which can easily cause pollution to marine and environmental waters. Meanwhile, the preparation of prepolymers largely relies on fossil-based polyols such as polyethers and polyesters. These raw materials are non-renewable, have high carbon emissions, and limited environmental friendliness, which does not conform to the trend of green development and cannot achieve a dual improvement in environmental protection and product performance. In addition, some color pastes contain heavy metal residues, which further affect environmental safety. Fourth, the preparation process is complex, the A / B component ratio requires strict precision, and the functional components and color pastes are prone to uneven dispersion, resulting in agglomeration, floating color and blooming, which affect the appearance and performance stability of the coating. Fifth, the adaptability to different scenarios is limited, making it difficult to meet the needs of multiple scenarios such as high humidity in the ocean, weather resistance of building exterior walls, and stain resistance and acid and alkali resistance of grout. Moreover, the decorative properties are insufficient and cannot adapt to the appearance and decoration requirements of different scenarios.

[0004] Among existing related technologies, such as the Zn²+ coordinated high-strength organosilicon modified polyurea marine antifouling coating disclosed in patent publication number CN 117986984 A, although it can improve mechanical properties and static antifouling ability, it adopts a single component system, has poor molding flexibility, and has no decorative function. It is only suitable for the single marine scenario and does not use biomass polyols such as castor oil, so its environmental protection and flexibility are still significantly lacking. The organosilicon modified polyurea antifouling material disclosed in patent publication number CN 112794975 A achieves non-toxic antifouling, but it does not adopt an A / B two-component system, has poor construction convenience, and does not add color paste, so its decorative effect is insufficient and it cannot achieve a synergistic improvement in environmental protection and mechanical properties. Summary of the Invention

[0005] The technical problem that the invention aims to solve

[0006] To address the problem that existing coating materials cannot simultaneously improve environmental friendliness and mechanical properties, this invention provides an environmentally friendly, long-lasting antifouling coating and its preparation method. The coating uses aliphatic isocyanate prepolymer and polyaspartic acid ester as core components. Components A and B have good compatibility and can be fully integrated to achieve the goal of preparing a two-component antifouling coating that is long-lasting, high-strength, environmentally friendly and non-toxic, has good decorative properties, is easy to prepare, and is suitable for multiple scenarios.

[0007] Technical solution To achieve the above objectives, the technical solution provided by the present invention is as follows: An environmentally friendly, long-lasting antifouling coating, comprising the following components by weight: 30-50 parts of component A, 25-45 parts of component B, 8-25 parts of functional agent, 1-5 parts of colorant, and 0.3-3 parts of additives; component A is an aliphatic isocyanate prepolymer, prepared by reacting aliphatic isocyanate with castor oil, specifically comprising 20-40 parts of aliphatic isocyanate and 10-20 parts of castor oil; Component B is polyaspartic acid ester with a molecular weight of 800-1500 g / mol. Castor oil is a renewable biomass raw material, which not only has the advantages of being environmentally friendly, renewable, and having low carbon emissions, but also contains long-chain fatty acid groups in its molecular structure. These groups have good reactivity and excellent compatibility with aliphatic isocyanates, and can achieve uniform reaction without the addition of any solvent. This can significantly improve the flexibility of the prepolymer (polyurea precursor) and its adhesion to the substrate. At the same time, it can optimize the compatibility between the polyurea precursor and polyaspartic acid ester with a molecular weight of 800-1500 g / mol, thereby improving the mechanical stability and weather resistance of the entire polyurea coating, achieving the goal of synergistic improvement in environmental protection and mechanical properties.

[0008] Further environmentally friendly and long-lasting antifouling coatings utilize polyaspartic acid esters, specifically one or a combination of polyaspartic acid esters PA-100 and PA-200. These esters exhibit moderate reactivity and excellent compatibility with component A (aliphatic isocyanate prepolymer), effectively enhancing the mechanical properties and weather resistance of the coating without releasing toxic or harmful substances. The functional components, by weight, include 5-15 parts of organosilicon-fluorocarbon composite modifier, 1-5 parts of antifouling agent, and 2-5 parts of nano-reinforcing filler, forming a composite functional body that provides antifouling, reinforcement, and weather resistance. The additives, by weight, include 0.1-1 parts of catalyst and 0.2-2 parts of antioxidant, which can adjust the reaction rate of components A and B, ensuring uniform coating formation.

[0009] Further environmentally friendly and long-lasting antifouling coatings utilize aliphatic isocyanates, specifically one or more of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate, in a mass ratio of 1:1 to 3:1. Castor oil is selected from hydroxyl-containing biomass plant oil polyols with a hydroxyl value of 160-170 mg KOH / g and a molecular weight of 920-950 g / mol. As a renewable biomass raw material, its molecular structure contains long-chain fatty acid groups and multiple terminal hydroxyl groups, exhibiting excellent compatibility with aliphatic isocyanates. A uniform reaction can be achieved without adding any solvent, significantly improving the flexibility, adhesion to the substrate, and compatibility with component B of the aliphatic isocyanate prepolymer (polyurea precursor). This also endows the coating with the advantages of being environmentally friendly, renewable, and having low carbon emissions.

[0010] The organosilicon-fluorocarbon composite modifier is a fluorocarbon-modified polysiloxane with a fluorine content of 10-20% and a silicon content of 30-50%. It can improve the hydrophobicity and antifouling properties of coatings through fluorocarbon segments and improve the flexibility and weather resistance of coatings through organosilicon segments. The antifouling agent is a nano-titanium dioxide-graphene composite antifouling agent with a particle size of 50-200nm and a mass ratio of 3:1-5:1. It contains no toxic biocides and has antibacterial, antifouling, and self-cleaning functions, which can effectively inhibit the adhesion of pollutants for a long time. The nano-reinforcing filler is one or a combination of nano-silica and nano-alumina with a particle size of 20-80nm, which can effectively improve the wear resistance and mechanical strength of coatings.

[0011] Further environmentally friendly and long-lasting antifouling coatings feature an isocyanate group content of 8-15% in the aliphatic isocyanate prepolymer, ensuring sufficient reaction with component B (polyaspartic acid ester) and further enhancing the mechanical and adhesive properties of the coating. The color paste is a blend of one or more of titanium dioxide pink paste, iron oxide red paste, and carbon black paste, and is a water-based environmentally friendly color paste with a particle size of 50-100nm. It has no heavy metal residue, excellent weather resistance, and the coating color can be adjusted according to the needs of different scenarios to meet various decorative requirements.

[0012] The antioxidant is one or a combination of antioxidant 1010 and antioxidant 168 to improve the coating’s aging resistance and UV resistance; the catalyst is one or a combination of dibutyltin dilaurate and bismuth isooctanoate.

[0013] A method for preparing the aforementioned environmentally friendly and long-lasting antifouling coating includes the following steps: preparing component A → preparing a mixture of component B → composite modification → composite molding of components A and B → coating and curing. This method simplifies the preparation process, reduces production costs, and ultimately enables large-scale, efficient industrial production.

[0014] Further preparation methods: Step S1: Add 20-40 parts of aliphatic isocyanate to a flask, stir and heat to 40-50℃, and slowly add 10-20 parts of castor oil at a dropping rate of 2-3 mL / min. Step S2: Add 25-45 parts of polyaspartic acid ester, 0.1-1 parts of catalyst, and 0.2-2 parts of antioxidant to a mixing tank, stir at room temperature for 10-15 minutes, add 1-5 parts of environmentally friendly color paste, and continue stirring for 15-20 minutes to obtain the B component mixture system; Step S3: Add 8-25 parts of the functional agent to the B component mixture system, stir at 1000-1200 r / min, and simultaneously ultrasonically disperse for 30-40 min to obtain the composite modified B component; Step S4: Slowly add 30-50 parts of component A to the composite modified component B at a dropping rate of 1-2 mL / min, and continue stirring at 800-1000 r / min. After the dropping is completed, continue stirring for 20-30 min to obtain the antifouling coating system. Step S5: Apply the antifouling coating system to the substrate surface, pre-dry at 60-80℃ for 15-25 minutes, then cure in sections, and allow to cool naturally to room temperature to obtain the finished antifouling coating.

[0015] Further preparation method: In step S3, the ultrasonic dispersion power is 200-300W, and the ultrasonic mode is ultrasonic for 5s followed by 3s intervals to achieve uniform dispersion of functional particles without agglomeration; In step S5, the coating thickness is 30-100μm, and the coating process is coating or spraying; The segmented curing is as follows: constant temperature curing at 100-110℃ for 20-30min, and constant temperature curing at 110-120℃ for 15-25min.

[0016] Further preparation method: In step S5, the substrate is one of metal substrate, concrete substrate, PET film, and ceramic tile substrate, which is suitable for different scenarios such as marine facilities, building exterior walls, food processing equipment, and tile grouting.

[0017] Beneficial effects Compared with the prior art, the technical solution provided by this invention has the following advantages: (1) The environmentally friendly and long-lasting antifouling coating of the present invention has excellent compatibility of A / B components and outstanding weather resistance: aliphatic isocyanate synthetic prepolymer is used as component A and polyaspartic acid ester is used as component B. The two have high reactivity matching degree, the reaction rate is easy to control, and the coating molding quality is stable. Compared with aromatic isocyanate, aliphatic isocyanate has significantly improved yellowing resistance and aging resistance. Combined with the excellent weather resistance of polyaspartic acid ester, the coating coating does not yellow or crack after long-term use (1000h after ultraviolet irradiation). The long-term use temperature range is -40℃ to 150℃, which can be adapted to harsh outdoor environments. (2) The environmentally friendly and long-lasting antifouling coating of the present invention has excellent and long-lasting antifouling performance: the organosilicon-fluorocarbon composite modifier and the environmentally friendly nano-titanium dioxide-graphene composite antifouling agent in the functional body work together to construct a low surface energy, antibacterial and self-cleaning antifouling surface layer. The water contact angle of the coating surface is ≥115°, which can effectively resist the adhesion of various pollutants such as oil, dust and marine organisms. The antifouling durability can reach more than 12 months. Compared with the existing two-component antifouling coating, the antifouling life is increased by more than 50%. The coating has no toxic biocides and no heavy metal residues. It is environmentally friendly and non-toxic, meets the requirements of green development, and can pass the French indoor air environment test A+ certification. It is suitable for food processing equipment, children's room grouting and other scenarios with strict environmental protection requirements. (3) The environmentally friendly and long-lasting antifouling coating of the present invention has outstanding mechanical properties and strong adhesion: through the reinforcing effect of nano-reinforced fillers, combined with the dense cross-linked network formed by the full reaction of A / B components, it effectively solves the technical problem that the mechanical properties and antifouling performance of existing antifouling coatings are difficult to coordinate; the finished coating has a tensile strength ≥25MPa, an elongation at break ≥350%, a peel strength to substrates such as metal, concrete, and ceramic tiles ≥2.5N / mm, and a Shore hardness of A60-A70. It has both high strength and good flexibility, is not easy to peel off or break, has excellent impact resistance, and can withstand complex environmental tests such as ocean wave impact and wind and rain erosion of building exterior walls; (4) The environmentally friendly and long-lasting antifouling coating of the present invention has both decorative and practical properties and is widely adaptable: the newly added water-based environmentally friendly pigment has no heavy metal residue and excellent weather resistance. The color of the coating can be flexibly adjusted according to the needs of different scenarios, taking into account both antifouling protection and decorative functions, and solving the problem of insufficient decoration of existing antifouling coatings. (5) The environmentally friendly and long-lasting antifouling coating of the present invention has a simple preparation process and can be mass-produced industrially: the A / B two-component preparation process is optimized, and the process of "preparing component A and modifying component B separately and then performing composite molding" is adopted. The preparation of component A does not require the addition of any solvent, which completely simplifies the process steps, reduces the purchase, storage and recycling of solvents, and the reaction conditions are mild (no high temperature and high pressure required) and the equipment requirements are low. The ultrasonic-high-speed shear synergistic dispersion technology is adopted to effectively avoid the agglomeration of functional bodies and pigments, and ensure that the coating system is uniform and stable and free from floating color and blooming. The A / B component ratio is flexible and the construction is convenient. It can be formed by coating, spraying and other processes. The production cost is reduced by 20-30% compared with the existing high-end two-component antifouling coatings, and it is easy to realize large-scale industrial production. (6) The environmentally friendly and long-lasting antifouling coating of the present invention has significant performance advantages due to the synergistic effect of biomass: The present invention uses castor oil as a biomass polyol to replace the traditional fossil-based polyol in the preparation of component A prepolymer; the biomass characteristics of castor oil not only endow the polyurea coating with better environmental performance (renewable, low emission, and degradable than fossil-based raw materials), but also the long-chain fatty acid groups in its molecular structure can effectively improve the flexibility of the polyurea molecular chain, solving the technical pain points of insufficient flexibility and easy cracking of traditional polyurea coatings; combined with its multiple terminal hydroxyl groups and aliphatic isocyanates The full reaction optimizes the polyurea cross-linking network structure, giving the coating both high strength and good toughness. Simultaneously, the biomass molecular structure of castor oil exhibits better compatibility with substrates (especially polar substrates such as concrete and ceramic tiles), significantly improving the adhesion strength between the polyurea coating and the substrate and reducing the risk of coating peeling. Furthermore, the biomass characteristics of castor oil, along with the synergistic effects of functional components and polyaspartic acid esters, further enhance the weather resistance and corrosion resistance of polyurea coatings, extending their service life and achieving a dual improvement in environmental friendliness and product performance, aligning with the development trend of the green coatings industry. Detailed Implementation

[0018] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments.

[0019] I. Testing Standards and Methods Antifouling performance is assessed using a static fouling test (immersion in artificial seawater or oil, observation of pollutant adhesion and recording of antifouling life) and a water contact angle test (according to GB / T 30693-2014). Mechanical properties are in accordance with GB / T 1040.1-2018 (tensile strength, elongation at break), GB / T 2792-2014 (peel strength), and GB / T 531.1-2008 (Shore hardness). Environmental performance is tested using GC-MS (pigment residue) and meets the French A+ indoor air quality certification standard; Weather resistance conforms to GB / T 1865-2009 (ultraviolet aging test); The corrosion resistance shall conform to GB / T 1763-1989 (acid and alkali resistance, seawater corrosion test). Decorative performance was assessed by visual observation (no floating color or blooming, uniform color) and scrub resistance test (according to GB / T 9266-2019).

[0020] Example 1 The environmentally friendly, long-lasting antifouling coating of this embodiment uses the following general specifications for its raw materials: Aliphatic isocyanates (IPDI purity 99.5%, HDI purity 99.5%); castor oil (industrial grade, hydroxyl value 160-170 mgKOH / g, molecular weight 920-950 g / mol, biomass vegetable oil polyol, renewable and environmentally friendly, containing long-chain fatty acid groups and multiple terminal hydroxyl groups in the molecule); polyaspartic acid esters (PA-100 molecular weight 1000 g / mol, PA-200 molecular weight 1200 g / mol); fluorocarbon modified polysiloxanes (containing 15% fluorine and 40% silicon); nano-titanium dioxide-graphene composite antifouling agent (particle size 100 nm, mass ratio 4:1); nano-silica (particle size 50 nm); water-based environmentally friendly color pastes (titanium dioxide pink paste, iron oxide red paste, particle size 80 nm, free of heavy metals); dibutyltin dilaurate (DBTDL, purity 98%); antioxidants 1010 and 168 (purity 99%).

[0021] Preparation method: The ambient temperature was controlled at 25±2℃ and the humidity at 50±5% throughout the process, under nitrogen atmosphere protection. The steps are as follows: S1. Preparation of Component A (Aliphatic Isocyanate Prepolymer): Add 25 parts by weight of IPDI to a four-necked flask, start stirring (600 r / min) and heat to 45℃, slowly add 15 parts of castor oil (industrial grade, hydroxyl value 160-170 mg KOH / g, molecular weight 920-950 g / mol) at a dropping rate of 2.5 mL / min; relying on the good compatibility between castor oil and IPDI, uniform reaction can be achieved without adding any solvent. After the addition is complete, stir the reaction at a constant temperature for 2.5 h to obtain an aliphatic isocyanate prepolymer (Component A) with an isocyanate group content (NCO%) of 12%, and seal for later use.

[0022] S2. Preparation of the component B mixture system: According to the weight, add 35 parts of polyaspartic acid ester PA-100 (component B), 0.5 parts of DBTDL, and 1 part of antioxidant 1010 to a mixing tank and stir at room temperature (700 r / min) for 12 min until the mixture is uniform; then add 2 parts of titanium dioxide environmentally friendly color paste (white) and continue stirring for 18 min to ensure that the color paste is uniformly dispersed and free from floating color and blooming, thus obtaining the component B mixture system.

[0023] S3. Composite Modification: Add 18 parts of functional agent (containing 10 parts of fluorocarbon modified polysiloxane, 3 parts of nano titanium dioxide-graphene composite antifouling agent, and 5 parts of nano silica) to the B component mixture system obtained in step S2. Adjust the stirring speed to 1100 r / min and simultaneously use 250W ultrasonic dispersion for 35 min (5 s ultrasonic, 3 s intermittent) to achieve uniform dispersion of the functional agent and the B component mixture system without agglomeration, thus obtaining the composite modified B component.

[0024] S4. A / B component composite molding: According to the weight, 40 parts of component A obtained in step S1 are slowly added dropwise to the composite modified component B obtained in step S3 at a dropping rate of 1.5 mL / min. During the dropping process, stirring is continued (900 r / min). After the dropping is completed, stirring is continued for 25 min to obtain a uniform white environmentally friendly long-lasting antifouling coating system.

[0025] S5. Coating and Curing: The antifouling coating system obtained in step S4 is uniformly coated onto the surface of a metal substrate using a coating machine (coating thickness 60μm), and placed in a hot air drying oven; it is first pre-dried at 70℃ for 20min to remove a small amount of water from the reaction byproducts in the system (since no solvent was used in component A, no additional solvent removal is required); then a segmented curing method is used: constant temperature curing at 105℃ for 25min, followed by constant temperature curing at 115℃ for 20min; after curing, it is naturally cooled to room temperature (25℃) to obtain a white, environmentally friendly, long-lasting antifouling coating product.

[0026] The environmentally friendly, long-lasting antifouling coating obtained in this embodiment has the following performance indicators: surface water contact angle 120°, antifouling durability 14 months; tensile strength 28 MPa, elongation at break 380%, peel strength to metal substrate 2.8 N / mm, Shore hardness A65. The excellent elongation at break and peel strength are attributed to the long-chain molecular structure of castor oil as a biomass polyol, which effectively improves the flexibility and adhesion of the polyurea coating to the substrate. The coating has a uniform color, no floating color or mottling, and is resistant to multiple scrubs. The coating has a lifespan of ≥5000 cycles; it leaves no toxic or harmful residues or solvent residues. Leveraging the biomass properties of castor oil, the coating's carbon emissions are reduced by more than 30% compared to traditional fossil-based polyurea coatings. It has passed the French A+ indoor air quality certification. After 1000 hours of UV irradiation, it shows no yellowing or cracking. After 72 hours of immersion in seawater, it exhibits no swelling or peeling, maintaining 93% of its mechanical properties. This finished product is suitable for marine facility protection scenarios, effectively resisting marine organism attachment and seawater corrosion, while also possessing excellent decorative properties and the environmental advantages of biomass.

[0027] Example 2 The environmentally friendly, long-lasting antifouling coating of this embodiment has the same basic formula, general specifications of raw materials, and process steps as in Embodiment 1. Except for the differences or improvements, the formula and general specifications of raw materials in Embodiment 1 are used: Preparation method: S1. Preparation of Component A (Aliphatic Isocyanate Prepolymer): Add 20 parts by weight of HDI to a four-necked flask, start stirring (500 r / min) and heat to 40℃, slowly add 10 parts of castor oil (industrial grade, hydroxyl value 160-170 mg KOH / g, molecular weight 920-950 g / mol) at a dropping rate of 2 mL / min; relying on the good compatibility between castor oil and HDI, uniform reaction can be achieved without adding any solvent. After the addition is complete, stir the reaction at a constant temperature for 2 h to obtain an aliphatic isocyanate prepolymer (Component A) with an isocyanate group content (NCO%) of 8%, and seal for later use.

[0028] S2. Preparation of the component B mixture system: According to the weight, add 25 parts of polyaspartic acid ester PA-200 (component B), 0.1 parts of bismuth isooctanoate, and 0.2 parts of antioxidant 168 to a mixing tank and stir at room temperature (600 r / min) for 10 min until the mixture is uniform; then add 1 part of iron oxide red environmentally friendly color paste (red) and continue stirring for 15 min to ensure that the color paste is uniformly dispersed and there is no floating color or blooming, thus obtaining the component B mixture system.

[0029] S3. Composite Modification: Add 8 parts of functional agent (containing 5 parts of fluorocarbon modified polysiloxane, 1 part of nano titanium dioxide-graphene composite antifouling agent, and 2 parts of nano alumina) to the B component mixture system obtained in step S2. Adjust the stirring speed to 1000 r / min and simultaneously use 200W ultrasonic dispersion for 30 min (5 s ultrasonic, 3 s intermittent) to achieve uniform dispersion of the functional agent and the B component mixture system without agglomeration, thus obtaining the composite modified B component.

[0030] S4. A / B component composite molding: According to the weight, 30 parts of component A obtained in step S1 are slowly added dropwise to the composite modified component B obtained in step S3 at a dropping rate of 1 mL / min. During the dropping process, stirring is continued (rotation speed 800 r / min). After the dropping is completed, stirring is continued for 20 min to obtain a uniform red environmentally friendly long-lasting antifouling coating system.

[0031] S5. Coating and Curing: The antifouling coating system obtained in step S4 is uniformly coated onto the surface of the ceramic tile substrate using a coating machine (coating thickness 30μm), and placed in a hot air drying oven; it is first pre-dried at 60℃ for 15min to remove a small amount of water from the reaction byproducts in the system (since no solvent was used in component A, no additional solvent removal is required); then a segmented curing method is adopted: constant temperature curing at 100℃ for 30min, followed by constant temperature curing at 110℃ for 25min; after curing, it is naturally cooled to room temperature (25℃) to obtain the finished red environmentally friendly long-lasting antifouling coating.

[0032] The environmentally friendly, long-lasting antifouling coating obtained in this embodiment has the following performance indicators: surface water contact angle 115°, antifouling durability 12 months; tensile strength 25MPa, elongation at break 350%, peel strength to ceramic tile substrate 2.5N / mm, Shore hardness A60; castor oil, as a biomass polyol, has excellent compatibility with ceramic tile substrate due to its polar groups, significantly improving the coating's adhesion, while its long-chain structure optimizes the coating's flexibility, effectively preventing cracking; the coating has a uniform color. It exhibits no floating color or blooming, and withstands ≥4500 scrub cycles; it contains no toxic or harmful substance residues or any solvent residues. Leveraging the renewable biomass characteristics of castor oil, it achieves a balance between environmental protection and performance, and has passed the French A+ indoor air quality certification. It shows no yellowing or cracking after 1000 hours of UV irradiation; after 72 hours of immersion in a 5% hydrochloric acid solution, it shows no swelling or peeling, maintaining 90% of its mechanical properties. This finished product is suitable for tile grouting, building exteriors, and other applications; it is stain-resistant, easy to clean, firmly adheres, and does not easily fall off, offering excellent decorative properties.

[0033] Example 3 The environmentally friendly, long-lasting antifouling coating of this embodiment has the same basic formula, general specifications of raw materials, and process steps as in Embodiment 1. Except for the differences or improvements, the formula and general specifications of raw materials in Embodiment 1 are used: Preparation method: S1. Preparation of Component A (Aliphatic Isocyanate Prepolymer): Add 40 parts by weight of the IPDI and HMDI compound (mass ratio 2:1) to a four-necked flask, start stirring (800 r / min) and heat to 50℃, slowly add 20 parts by weight of castor oil (industrial grade, hydroxyl value 160-170 mg KOH / g, molecular weight 920-950 g / mol) at a dropping rate of 3 mL / min; relying on the good compatibility between castor oil and aliphatic isocyanate compound, uniform reaction can be achieved without adding any solvent. After the addition is complete, stir the reaction at a constant temperature for 3 h to obtain an aliphatic isocyanate prepolymer (Component A) with an isocyanate group content (NCO%) of 15%, and seal for later use.

[0034] S2. Preparation of Component B Mixture System: By weight, add 45 parts of polyaspartic acid ester PA-100 and PA-200 compound (mass ratio 1:1), 1 part of DBTDL and bismuth isooctanoate compound (mass ratio 1:1), and 2 parts of antioxidant 1010 and antioxidant 168 compound (mass ratio 1:1) to a mixing tank and stir at room temperature (800 r / min) for 15 min until uniformly mixed; then add 5 parts of carbon black and titanium dioxide compound environmentally friendly color paste (gray) and continue stirring for 20 min to ensure uniform dispersion of the color paste without floating color or blooming, thus obtaining the Component B Mixture System.

[0035] S3. Composite Modification: Add 25 parts of functional agent (containing 15 parts of fluorocarbon modified polysiloxane, 5 parts of nano-titanium dioxide-graphene composite antifouling agent, and 5 parts of nano-silica and nano-alumina composite (mass ratio 1:1)) to the B component mixture system obtained in step S2. Adjust the stirring speed to 1200 r / min and simultaneously use 300W ultrasonic dispersion for 40 min (5 s ultrasonic, 3 s intermittent) to achieve uniform dispersion of the functional agent and the B component mixture system without agglomeration, thus obtaining the composite modified B component.

[0036] S4. A / B component composite molding: By weight, 50 parts of component A obtained in step S1 are slowly added dropwise to the composite modified component B obtained in step S3 at a dropping rate of 2 mL / min. During the dropping process, stirring is continued (speed 1000 r / min). After the dropping is completed, stirring is continued for 30 min to obtain a uniform gray environmentally friendly long-lasting antifouling coating system.

[0037] S5. Coating and Curing: The antifouling coating system obtained in step S4 is uniformly coated onto the surface of a concrete substrate using a spraying process (coating thickness 100μm), and placed in a hot air drying oven; it is first pre-dried at 80℃ for 25min to remove a small amount of water from the reaction byproducts in the system (since no solvent was used in component A, no additional solvent removal is required); then a segmented curing method is used: constant temperature curing at 110℃ for 20min, followed by constant temperature curing at 120℃ for 15min; after curing, it is naturally cooled to room temperature (25℃) to obtain the finished gray environmentally friendly long-lasting antifouling coating.

[0038] The environmentally friendly, long-lasting antifouling coating obtained in this embodiment exhibits the following performance indicators: surface water contact angle 125°, antifouling durability 16 months; tensile strength 32 MPa, elongation at break 420%, peel strength from concrete substrate 3.2 N / mm, and Shore hardness A70. Castor oil, as a biomass polyol, forms hydrogen bonds between its long-chain fatty acid groups and the hydroxyl groups of the concrete substrate, significantly improving adhesion strength. Simultaneously, it optimizes the polyurea crosslinking network, achieving a synergistic effect of high strength and high toughness, resulting in performance superior to polyurea prepared from traditional fossil-based polyols. The coating has a uniform color, no floating color or mottling, and can withstand ≥5500 scrub cycles. It contains no toxic or harmful residues or solvent residues. The biomass renewable properties of castor oil further enhance the coating's environmental value, and it has passed the French A+ indoor air quality certification. It shows no yellowing or cracking after 1000 hours of UV irradiation. After 72 hours of immersion in seawater, it shows no swelling or peeling, and retains 95% of its mechanical properties. This finished product is suitable for building exteriors, municipal facilities, and other applications. It exhibits excellent weather resistance and corrosion resistance, and can withstand long-term wind and rain erosion and pollutant adhesion, combining decorative, practical, and environmentally friendly properties.

[0039] Through Examples 1-3, the antifouling coating obtained has a water contact angle ≥115°, antifouling durability ≥12 months, tensile strength ≥25MPa, elongation at break ≥350%, peel strength from substrate ≥2.5N / mm, Shore hardness A60-A70, scrub resistance ≥4500 cycles, no toxic or harmful substance residues, and has passed the French indoor air quality testing A+ certification.

[0040] Comparative Example 1 A two-component antifouling coating is prepared using existing technology. The formulation and process are basically the same as those in Example 1. The core difference is that component A uses aromatic isocyanate (MDI) to prepare the prepolymer, and component B uses amino-terminated polyether D-400 instead of polyaspartic acid ester. No environmentally friendly color paste or organosilicon-fluorocarbon composite modifier is added (consistent with Example 1, component A does not use any solvent). The specifications, dosages and process parameters of the remaining raw materials are consistent with those in Example 1 (the detection methods are the same).

[0041] The antifouling coating prepared in this comparative example exhibits the following performance indicators: surface water contact angle 90°, antifouling durability 8 months, but easily attracts oil and dust; tensile strength 15MPa, elongation at break 200%, peel strength from metal substrate 1.2N / mm, Shore hardness A50, poor mechanical properties, prone to peeling and cracking; no decorative function (colorless); obvious yellowing after 1000h of UV irradiation; slight swelling after 72h of seawater immersion, with a mechanical property retention rate of 75%; no toxic or harmful substance residues, but its antifouling performance, mechanical properties, weather resistance, and decorative properties are all far lower than those of Example 1 of this invention, and the reaction rate of components A / B is unstable, resulting in poor molding quality.

[0042] Comparative Example 2 A two-component antifouling coating has the same formulation and process parameters as in Example 1. The core difference is that component B uses amino-terminated polyether D-2000 instead of polyaspartic acid ester, and no functional agents (organosilicon-fluorocarbon composite modifier, environmentally friendly antifouling agent, and nano-reinforcing filler) are added. In component A, castor oil is replaced with hydroxyl-terminated polyether D-2000. The remaining raw material dosages and preparation steps are exactly the same as in Example 1 (the raw material specifications, equipment, and testing methods are the same).

[0043] Testing revealed the following performance indicators for the antifouling coating prepared in this comparative ratio: surface water contact angle 85°, antifouling durability 3 months (no long-term antifouling function); tensile strength 18 MPa, elongation at break 250%, peel strength to metal substrate 1.8 N / mm, Shore hardness A55. Mechanical properties showed a significant decline, particularly in elongation at break and peel strength. The core reason is that the replaced hydroxyl-terminated polyether (fossil-based) lacks the long-chain molecular structure and polar groups of castor oil as a biomass polyol, failing to improve coating flexibility and substrate adhesion, and lacking a synergistic effect of reinforcement and toughening. It lacks flexibility and is prone to cracking when bent; the color is uniform (white), but the number of scrubs it can withstand is only 2000; it shows slight yellowing after 1000 hours of UV irradiation; after immersion in seawater for 72 hours, there is no swelling or peeling, and the mechanical properties are retained at 82%; the decorative properties are acceptable, but the anti-fouling performance and mechanical properties are significantly inferior, and it lacks the biomass environmental advantages brought by castor oil, making it unsuitable for complex application scenarios. At the same time, the compatibility of components A and B is poor, and uneven molding is likely to occur, further highlighting the key role of castor oil as a biomass in improving the performance of polyurea (this comparative example is the same as Example 1, and no solvent is used in component A).

[0044] Comparative Example 3 A two-component antifouling coating has the same formulation and process parameters as Example 1. The core difference is that no environmentally friendly colorant is added, and the composite modification step does not use ultrasonic dispersion, but only stirring dispersion. The remaining raw material dosage and preparation steps are exactly the same as in Example 1 (the raw material specifications, equipment, and testing methods are the same).

[0045] The antifouling coating prepared in this comparative proportion exhibits the following performance indicators: surface water contact angle 118°, antifouling durability 13 months, indicating good antifouling performance; tensile strength 22MPa, elongation at break 320%, peel strength to metal substrate 2.2N / mm, Shore hardness A62, with a slight decrease in mechanical properties (due to functional body agglomeration); no decorative function (colorless); uneven dispersion of functional bodies, resulting in a grainy texture on the coating surface; no yellowing after 1000 hours of UV irradiation; no swelling or peeling after 72 hours of seawater immersion, with a mechanical property retention rate of 88%; insufficient mechanical properties and decorative properties, along with poor coating appearance quality, fail to meet the decorative requirements of scenarios such as building exteriors, highlighting the important role of environmentally friendly pigments and ultrasonic dispersion technology in this invention.

[0046] A comparison of Examples 1-3 and Comparative Examples 1-3 shows that this invention, by using aliphatic isocyanate prepolymer as component A and polyaspartic acid ester as component B, synergistically combining functional components and environmentally friendly pigments, and employing an optimized A / B two-component preparation process (where component A preparation requires no solvent addition and relies on the good compatibility between castor oil and aliphatic isocyanate to achieve a uniform reaction), successfully solves the technical problems of poor compatibility between A / B components, insufficient antifouling durability, difficulty in synergizing mechanical and antifouling properties, and lack of decorative properties in existing two-component antifouling coatings. The antifouling life is increased by more than 50%, demonstrating significant effects. Crucially, this invention uses castor oil as a biomass polyol to replace traditional fossil-based polyols in preparing the component A prepolymer. The biomass characteristics of castor oil not only endow the coating with superior environmental friendliness, renewability, and low carbon emission advantages, but its molecular structure also synergistically improves the flexibility, substrate adhesion, mechanical stability, and weather resistance of the polyurea coating. Furthermore, the uniform reaction can be achieved without adding solvents, further enhancing environmental friendliness. This invention offers several advantages over existing technologies that utilize fossil-based polyols. It aligns better with green development trends, boasts superior core performance, and allows for adjustments to coating thickness, color, and substrate type based on specific needs. It is compatible with various substrates such as metal, concrete, ceramic tiles, and PET film, making it widely applicable to marine facilities (ship bottoms, buoys), building exteriors, food processing equipment, tile grouting, and municipal facilities. Its versatility is exceptional. Furthermore, it exhibits excellent antifouling properties, mechanical properties, weather resistance, environmental friendliness, and decorative appeal. The preparation process is simple, production costs are low, and it is widely adaptable to various scenarios, enabling large-scale industrial production. Compared to existing technologies, it possesses significant technological advantages and practical value. This two-component antifouling coating features good A / B component compatibility, uses aliphatic isocyanate prepolymer and polyaspartic acid ester as core components, and incorporates castor oil biomass polyols to enhance environmental friendliness and key performance characteristics. It offers long-lasting antifouling, high strength, environmental friendliness and non-toxicity, excellent decorative properties, simple preparation, and adaptability to multiple scenarios.

[0047] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual structure and manufacturing steps are not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly, long-lasting antifouling coating, characterized in that, The weight percentages of each component include: 30-50 parts of component A, 25-45 parts of component B, 8-25 parts of functional agent, 1-5 parts of color paste, and 0.3-3 parts of additives; wherein: Component A is an aliphatic isocyanate prepolymer, which is prepared by reacting aliphatic isocyanate with castor oil. The specific raw materials and weight ratios include 20-40 parts of aliphatic isocyanate and 10-20 parts of castor oil. Component B is polyaspartic acid ester with a molecular weight of 800-1500 g / mol.

2. The environmentally friendly, long-lasting antifouling coating according to claim 1, characterized in that: The polyaspartic acid ester is one or a combination of two of polyaspartic acid esters PA-100 and PA-200. The functional components, by weight, include: 5-15 parts of organosilicon-fluorocarbon composite modifier, 1-5 parts of antifouling agent, and 2-5 parts of nano-reinforcing filler; The additives include 0.1-1 parts of catalyst and 0.2-2 parts of antioxidant by weight.

3. The environmentally friendly, long-lasting antifouling coating according to claim 2, characterized in that: The aliphatic isocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, in a mass ratio of 1:1 to 3:1; the castor oil is selected from hydroxyl biomass vegetable oil polyols with a hydroxyl value of 160-170 mgKOH / g and a molecular weight of 920-950 g / mol. The organosilicon-fluorocarbon composite modifier is a fluorocarbon-modified polysiloxane with a fluorine mass fraction of 10-20% and a silicon mass fraction of 30-50%; the antifouling agent is a nano-titanium dioxide-graphene composite antifouling agent with a particle size of 50-200 nm and a mass ratio of 3:1-5:1; the nano-reinforcing filler is one or a combination of nano-silica and nano-alumina with a particle size of 20-80 nm.

4. The environmentally friendly, long-lasting antifouling coating according to claim 3, characterized in that: The isocyanate group content in the aliphatic isocyanate prepolymer is 8-15%; the color paste is one or more of titanium dioxide pink paste, iron oxide red paste and carbon black paste. The antioxidant is one or a combination of antioxidant 1010 and antioxidant 168; The catalyst is one or a combination of two of dibutyltin dilaurate and bismuth isooctanoate, which can precisely adjust the reaction rate of components A / B to ensure uniform coating formation.

5. A method for preparing an environmentally friendly, long-lasting antifouling coating according to any one of claims 1-4, characterized in that, The steps are as follows: S1. Prepare component A; S2. Prepare the mixture system of component B; S3, composite modification; S4, A and B components are composite molded; S5, Coating and Curing.

6. The preparation method according to claim 5, characterized in that: Step S1: Add 20-40 parts of aliphatic isocyanate to a flask, stir and heat to 40-50℃, and slowly add 10-20 parts of castor oil at a dropping rate of 2-3 mL / min. Step S2: Add 25-45 parts of polyaspartic acid ester, 0.1-1 parts of catalyst, and 0.2-2 parts of antioxidant to a mixing tank, stir at room temperature for 10-15 minutes, add 1-5 parts of environmentally friendly color paste, and continue stirring for 15-20 minutes to obtain the B component mixture system; Step S3: Add 8-25 parts of functional agent to the B component mixing system, stir at 1000-1200 r / min, and simultaneously ultrasonically disperse for 30-40 min to obtain composite modified B component; Step S4: Slowly add 30-50 parts of component A to the composite modified component B at a dropping rate of 1-2 mL / min, and continue stirring at 800-1000 r / min. After the dropping is completed, continue stirring for 20-30 min to obtain the antifouling coating system. Step S5: Apply the antifouling coating system to the surface of the substrate, pre-dry at 60-80℃ for 15-25 minutes, then cure in sections, and naturally cool to room temperature to obtain the finished antifouling coating.

7. The preparation method according to claim 6, characterized in that: In step S3, the ultrasonic dispersion power is 200-300W, and the ultrasonic mode is ultrasonic for 5 seconds followed by an interval of 3 seconds; in step S5, the coating thickness is 30-100μm, and the coating process is coating or spraying; the segmented curing is specifically: constant temperature curing at 100-110℃ for 20-30 minutes, and constant temperature curing at 110-120℃ for 15-25 minutes.

8. The preparation method according to claim 7, characterized in that: The substrate mentioned in step S5 is one of the following: metal substrate, concrete substrate, PET film, and ceramic tile substrate.